Abas, AEP, Yong, J, Mahlia, TMI & Hannan, MA 2019, 'Techno-Economic Analysis and Environmental Impact of Electric Vehicle', IEEE Access, vol. 7, pp. 98565-98578.
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Abas, PE & Mahlia, TMI 2019, 'Techno-Economic and Sensitivity Analysis of Rainwater Harvesting System as Alternative Water Source', Sustainability, vol. 11, no. 8, pp. 2365-2365.
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This paper formulates a rainwater harvesting model, with system and economic measures to determine the feasibility of a rainwater harvesting system, which uses water from the mains to complement the system. Although local meteorological and market data were used to demonstrate the model, it can also be easily adapted for analysis of other localities. Analysis has shown that an optimum tank size exists, which minimizes the cost per unit volume of water. Economic performance measures have indicated that rainwater harvesting system is currently infeasible to be implemented in Brunei; with capital cost and water price being shown to be among the prohibiting factors. To improve feasibility, a combination of rebate scheme on capital cost and raising the current water price has been proposed. It has also been shown that the system is more viable for households with high water demand.
Abdelkarim, A, Gaber, A, Youssef, A & Pradhan, B 2019, 'Flood Hazard Assessment of the Urban Area of Tabuk City, Kingdom of Saudi Arabia by Integrating Spatial-Based Hydrologic and Hydrodynamic Modeling', Sensors, vol. 19, no. 5, pp. 1024-1024.
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This study deals with the use of remote sensing (RS), geographic information systems (GISs), hydrologic modeling (water modeling system, WMS), and hydraulic modeling (Hydrologic Engineering Center River Analysis System, HEC-RAS) to evaluate the impact of flash flood hazards on the sustainable urban development of Tabuk City, Kingdom of Saudi Arabia (KSA). Determining the impact of flood hazards on the urban area and developing alternatives for protection and prevention measures were the main aims of this work. Tabuk City is exposed to frequent flash flooding due to its location along the outlets of five major wadis. These wadis frequently carry flash floods, seriously impacting the urban areas of the city. WMS and HEC-HMS models and RS data were used to determine the paths and morphological characteristics of the wadis, the hydrographic flow of different drainage basins, flow rates and volumes, and the expansion of agricultural and urban areas from 1998 to 2018. Finally, hydraulic modeling of the HEC-RAS program was applied to delineate the urban areas that could be inundated with floodwater. Ultimately, the most suitable remedial measures are proposed to protect the future sustainable urban development of Tabuk City from flood hazards. This approach is rarely used in the KSA. We propose a novel method that could help decision-makers and planners in determining inundated flood zones before planning future urban and agricultural development in the KSA.
Abdollahi, A, Pradhan, B & Shukla, N 2019, 'Extraction of road features from UAV images using a novel level set segmentation approach', International Journal of Urban Sciences, vol. 23, no. 3, pp. 391-405.
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© 2019, © 2019 The Institute of Urban Sciences. A novel hybrid technique for road extraction from UAV imagery is presented in this paper. The suggested analysis begins with image segmentation via Trainable Weka Segmentation. This step uses an immense range of image features, such as detectors for edge detection, filters for texture, filters for noise depletion and a membrane finder. Then, a level set method is performed on the segmented images to extract road features. Next, morphological operators are applied on the images for improving extraction precision. Eventually, the road extraction precision is calculated on the basis of manually digitized road layers. Obtained results indicated that the average proportions of completeness, correctness and quality were 93.52%, 85.79% and 81.01%, respectively. Therefore, experimental results validated the superior performance of the proposed hybrid approach in road extraction from UAV images.
Abdulkareem, JH, Pradhan, B, Sulaiman, WNA & Jamil, NR 2019, 'Development of lag time and time of concentration for a tropical complex catchment under the influence of long-term land use/land cover (LULC) changes', Arabian Journal of Geosciences, vol. 12, no. 3.
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© 2019, Saudi Society for Geosciences. Lag time (t L ) and time of concentration (T c ) are essential time parameters used in hydrological flood-flow design methods for estimating peak discharge and flood hydrograph shape. They form the basis of a number of hydrological models used among the scientists. Kelantan River basin, Malaysia, is a tropical catchment receiving heavy monsoon rainfall coupled with intense land use/land cover (LULC) changes making the area consistently flood prone thereby deteriorating water balance in the area. The most recent is that of December 2014 flood which lead to catastrophic loss of huge amount of properties worth millions of Malaysian ringgit. In view of this, the current research was conducted with the aim of developing (1) t L and T c based on 1984, 2002, and 2013 LULC conditions; (2) a relationship between t L and t L parameters; and (3) a relationship between t L and T c among different LULC conditions. Kelantan River basin was first delineated into four major catchments, viz., Galas, Pergau, Lebir, and Nenggiri, due to its large size (approximately 13,100 km 2 ). Soil map and LULC change maps corresponding to 1984, 2002, and 2013 were used for the calculation of CN values while NRCS lag equation was used for the estimation of t L and T c . The results showed that deforestation for logging activities and agricultural practices were the dominant LULC changes across the watershed. Low values of both t L and T c were obtained across the catchment which are typical for a tropical monsoon catchment characterized with high runoff and short peak discharge. Results of t L and T c in this study are not affected by LULC changes in the basin. Slope was observed to be highly correlated with t L . Correlation coefficient was used to determine the relationship between t L and t L factor, and hydraulic length and slope (L√S). The results showed high correlation in all the catchments from 1984 to 2013 except for Lebir catchment wher...
Abdulkareem, JH, Pradhan, B, Sulaiman, WNA & Jamil, NR 2019, 'Long-term runoff dynamics assessment measured through land use/cover (LULC) changes in a tropical complex catchment', Environment Systems and Decisions, vol. 39, no. 1, pp. 16-33.
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© 2018, Springer Science+Business Media, LLC, part of Springer Nature. The estimation of excess rainfall is critically important in water resource management as it provides the basis for calculating flood peak discharge that results in surface runoff. Kelantan River basin in Malaysia is a tropical catchment receiving heavy monsoon rainfall coupled with intense land use/cover (LULC) changes making the area consistently flood prone. The current study is therefore aimed to achieve the following goals: (1) to develop a curve number (CN) and runoff maps for 1984, 2002, and 2013 LULC conditions and (2) to determine runoff dynamics due to changes in LULC as well as to assess how the extent of LULC change will affect surface runoff generation. To achieve the aforementioned goals, land use maps corresponding to 1984, 2002, and 2014 LULC conditions were analyzed and prepared for the calculation of CN values using Soil Conservation Service (SCS-CN) method. CN and runoff maps corresponding to 1984, 2002, and 2013 LULC changes were successfully developed and the performance of the method was tested. The results indicated that forest was found to be the major land use type to have changed in all the LULC conditions across the watershed leading to intense runoff dynamics in the entire watershed. Higher runoff values were observed under 2013 LULC conditions across the watershed mainly due to intense deforestation relative to those of 1984 and 2002. The results of this study indicated that runoff generation is significantly affected by deforestation instead of changes in the rainfall pattern. The findings may be useful to water resource planners in controlling water loss for future planning.
Abdulkareem, JH, Pradhan, B, Sulaiman, WNA & Jamil, NR 2019, 'Prediction of spatial soil loss impacted by long-term land-use/land-cover change in a tropical watershed', Geoscience Frontiers, vol. 10, no. 2, pp. 389-403.
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© 2017 China University of Geosciences (Beijing) and Peking University. The devastating effect of soil erosion is one of the major sources of land degradation that affects human lives in many ways which occur mainly due to deforestation, poor agricultural practices, overgrazing, wildfire and urbanization. Soil erosion often leads to soil truncation, loss of fertility, slope instability, etc. which causes irreversible effects on the poorly renewable soil resource. In view of this, a study was conducted in Kelantan River basin to predict soil loss as influenced by long-term land use/land-cover (LULC) changes in the area. The study was conducted with the aim of predicting and assessing soil erosion as it is influenced by long-term LULC changes. The 13,100 km 2 watershed was delineated into four sub-catchments Galas, Pergau, Lebir and Nenggiri for precise result estimation and ease of execution. GIS-based Universal Soil Loss Equation (USLE) model was used to predict soil loss in this study. The model inputs used for the temporal and spatial calculation of soil erosion include rainfall erosivity factor, topographic factor, land cover and management factor as well as erodibility factor. The results showed that 67.54% of soil loss is located under low erosion potential (reversible soil loss) or 0-1 t ha -1 yr -1 soil loss in Galas, 59.17% in Pergau, 53.32% in Lebir and 56.76% in Nenggiri all under the 2013 LULC condition. Results from the correlation of soil erosion rates with LULC changes indicated that cleared land in all the four catchments and under all LULC conditions (1984-2013) appears to be the dominant with the highest erosion losses. Similarly, grassland and forest were also observed to regulate erosion rates in the area. This is because the vegetation cover provided by these LULC types protects the soil from direct impact of rain drops which invariably reduce soil loss to the barest minimum. Overall, it was concluded that the results have shown the significan...
Abnisa, F, Anuar Sharuddin, SD, bin Zanil, MF, Wan Daud, WMA & Indra Mahlia, TM 2019, 'The Yield Prediction of Synthetic Fuel Production from Pyrolysis of Plastic Waste by Levenberg–Marquardt Approach in Feedforward Neural Networks Model', Polymers, vol. 11, no. 11, pp. 1853-1853.
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The conversion of plastic waste into fuel by pyrolysis has been recognized as a potential strategy for commercialization. The amount of plastic waste is basically different for each country which normally refers to non-recycled plastics data; consequently, the production target will also be different. This study attempted to build a model to predict fuel production from different non-recycled plastics data. The predictive model was developed via Levenberg-Marquardt approach in feed-forward neural networks model. The optimal number of hidden neurons was selected based on the lowest total of the mean square error. The proposed model was evaluated using the statistical analysis and graphical presentation for its accuracy and reliability. The results showed that the model was capable to predict product yields from pyrolysis of non-recycled plastics with high accuracy and the output values were strongly correlated with the values in literature.
Adanta, D, ., B, ., W, Quaranta, E & I. Mahlia, TM 2019, 'Investigation of the effect of gaps between the blades of open flume Pico hydro turbine runners', Journal of Mechanical Engineering and Sciences, vol. 13, no. 3, pp. 5493-5512.
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This study will analyze the impact of gap size in two different runners called runner A (five blades) and B (six blades) to provides recommendations in design and manufacture of open flume turbine runners so that maximize the conversion of kinetic and potential energy. There are three methods was used to investigate its: analytical method is used to design the turbine; experimental to determine the actual turbine performance; computational fluid dynamics (CFD) to study the physical phenomena and re-check the velocity triangle on the runner to validate the design and manufacturing process. Using the results obtained, gaps between the blades can alter the velocity vector on the outlet and unbalance the rotation of runner; this imbalance could cause cavitation. Then, the decreasing torque is assumed because water pressure in the draft tube is similar to atmospheric pressure. Two conditions must be satisfied to maximize the performance of the turbine: swirling flow is required after the water flows past the runner in order to minimize the radial velocity on the outlet so that the draft tube can function properly; the dimensions of the blade must be carefully selected to avoid the formation of gaps between the blades.
Ahmed II, JB & Pradhan, B 2019, 'Spatial assessment of termites interaction with groundwater potential conditioning parameters in Keffi, Nigeria', Journal of Hydrology, vol. 578, pp. 124012-124012.
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© 2019 Elsevier B.V. Termite mounds are traditionally presumed to be good indicators of groundwater in places they inhabit but this hypothesis is yet to be scientifically substantiated. To confirm this assertion, it is expected that termite mounds would have strong correlations with groundwater conditioning parameters (GCPs). In this study, termite mounds distribution covering an area of about 156 km2 were mapped and their structural characteristics documented with the aim of examining their relationships with twelve (12) chosen GCPs. Other specific objectives were to identify specific mound types with affinity to groundwater and to produce a groundwater potential map of the study area. To achieve this, 12 GCPs including geology, drainage density, lineament density, lineament intersection density, land use/land cover, topographic wetness index (TWI), normalized difference vegetation index (NDVI), slope, elevation, plan curvature, static water level and groundwater level fluctuation were extracted from relevant sources. Frequency ratio (FR) and Spearman's rank correlation were used to find relationships and direction of such relationships. The result revealed a consistent agreement between FR and Spearman's rank correlation that tall (≥1.8 m) and Cathedral designed mounds are good indicators of groundwater. Further, the groundwater potential map produced from the Random Forest (RF) model via Correlation-based Feature Selection (CFS) using best-first algorithm depicted an erratic nature of groundwater distribution in the study area. This was then classified using natural break into very-high, high, moderate, low and very low potential classes and area under curve (AUC) of the receiver operating characteristics (ROC) showed an 86.5% validity of the model. About 75% of mapped termite mounds fell within the very-high to moderate potential classes thereby suggesting that although tall and cathedral mounds in particular showed good correlations with a number of GCPs, hi...
Ahmed II, JB, Pradhan, B, Mansor, S, Yusoff, ZM & Ekpo, SA 2019, 'Aquifer Potential Assessment in Termites Manifested Locales Using Geo-Electrical and Surface Hydraulic Measurement Parameters', Sensors, vol. 19, no. 9, pp. 2107-2107.
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In some parts of tropical Africa, termite mound locations are traditionally used to site groundwater structures mainly in the form of hand-dug wells with high success rates. However, the scientific rationale behind the use of mounds as prospective sites for locating groundwater structures has not been thoroughly investigated. In this paper, locations and structural features of termite mounds were mapped with the aim of determining the aquifer potential beneath termite mounds and comparing the same with adjacent areas, 10 m away. Soil and species sampling, field surveys and laboratory analyses to obtain data on physical, hydraulic and geo-electrical parameters from termite mounds and adjacent control areas followed. The physical and hydraulic measurements demonstrated relatively higher infiltration rates and lower soil water content on mound soils compared with the surrounding areas. To assess the aquifer potential, vertical electrical soundings were conducted on 28 termite mounds sites and adjacent control areas. Three (3) important parameters were assessed to compute potential weights for each Vertical Electrical Sounding (VES) point: Depth to bedrock, aquifer layer resistivity and fresh/fractured bedrock resistivity. These weights were then compared between those of termite mound sites and those from control areas. The result revealed that about 43% of mound sites have greater aquifer potential compared to the surrounding areas, whereas 28.5% of mounds have equal and lower potentials compared with the surrounding areas. The study concludes that termite mounds locations are suitable spots for groundwater prospecting owing to the deeper regolith layer beneath them which suggests that termites either have the ability to locate places with a deeper weathering horizon or are themselves agents of biological weathering. Further studies to check how representative our study area is of other areas with similar termite activities are recommended.
Ahmed, AA & Pradhan, B 2019, 'Vehicular traffic noise prediction and propagation modelling using neural networks and geospatial information system', Environmental Monitoring and Assessment, vol. 191, no. 3.
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© 2019, Springer Nature Switzerland AG. This study proposes a neural network (NN) model to predict and simulate the propagation of vehicular traffic noise in a dense residential area at the New Klang Valley Expressway (NKVE) in Shah Alam, Malaysia. The proposed model comprises of two main simulation steps: that is, the prediction of vehicular traffic noise using NN and the simulation of the propagation of traffic noise emission using a mathematical model. First, the NN model was developed with the following selected noise predictors: the number of motorbikes, the sum of vehicles, car ratio, heavy vehicle ratio (e.g. truck, lorry and bus), highway density and a light detection and ranging (LiDAR)-derived digital surface model (DSM). Subsequently, NN and its hyperparameters were optimised by a systematic optimisation procedure based on a grid search approach. The noise propagation model was then developed in a geographic information system (GIS) using five variables, namely road geometry, barriers, distance, interaction of air particles and weather parameters. The noise measurement was conducted continuously at 15-min intervals and the data were analysed by taking the minimum, maximum and average values recorded during the day. The measurement was performed four times a day (i.e. morning, afternoon, evening, and midnight) over two days of the week (i.e. Sunday and Monday). An optimal radial basis function NN was used with 17 hidden layers. The learning rate and momentum values were 0.05 and 0.9, respectively. Finally, the accuracy of the proposed method achieved 78.4% with less than 4.02 dB (A) error in noise prediction. Overall, the proposed models were found to be promising tools for traffic noise assessment in dense urban areas.
Ahmed, MB, Hasan Johir, MA, Zhou, JL, Ngo, HH, Nghiem, LD, Richardson, C, Moni, MA & Bryant, MR 2019, 'Activated carbon preparation from biomass feedstock: Clean production and carbon dioxide adsorption', Journal of Cleaner Production, vol. 225, pp. 405-413.
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© 2019 Elsevier Ltd The current methods used for the production of activated carbon (AC) are often chemical and energy intensive and produce significant amount of chemical waste. Thus, clean production of AC is important to reduce its overall production cost and to limit the adverse effect on the environment. Therefore, the main aim of this study is to develop a clean method for AC production from woody biomass with low chemical consumption. Herein, this study reports a facile strategy for reducing chemical usages in the production of high-performance AC, by introducing a crucial pre-pyrolysis step before chemical activation of biomass. The ACs prepared were characterised using scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen and carbon dioxide gas adsorption measurements. All these characterisations indicated that produced ACs have similar physicochemical properties. The strategy reduced chemical use by 70% and produced high-performance ultra-microporous ACs with excellent carbon dioxide adsorption capacity (4.22–5.44 mmol m −2 ). The facile pre-pyrolysis method is recommended for further research as a cleaner activated carbon preparation method from biomass feedstock.
Ajibola, II, Mansor, S, Pradhan, B & Mohd. Shafri, HZ 2019, 'Fusion of UAV-based DEMs for vertical component accuracy improvement', Measurement, vol. 147, pp. 106795-106795.
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© 2019 Elsevier Ltd Most construction projects require data that comply with a certain standard of accuracy both in the horizontal and vertical components. This study aimed to develop a model for improving the quality of Digital Elevation Model (DEM) produced by UAV. UAV is the short form of Unmanned Aerial Vehicle, which is either fixed-wing or rotorcraft type. The study proposes a fusion approach that integrates a weighted averaging and additive median filtering algorithms to improve accuracy of the DEMs derived from fixed-wing UAVs. The low quality DEM was fused with high quality DEM produced by multi-rotor UAVs. Assessment of the DEM produced root mean square error of 1.14 cm and standard vertical accuracy of 2.24 cm at a 95% confidence level. This value represents a decrease in vertical standard error of 18.31 cm to 2.24 cm, which is an improvement of 88%. The result of the study indicates that the method is suitable for improving accuracy of DEM produced by UAVs.
Akther, N, Daer, S, Wei, Q, Janajreh, I & Hasan, SW 2019, 'Synthesis of polybenzimidazole (PBI) forward osmosis (FO) membrane and computational fluid dynamics (CFD) modeling of concentration gradient across membrane surface', Desalination, vol. 452, pp. 17-28.
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Akther, N, Lim, S, Tran, VH, Phuntsho, S, Yang, Y, Bae, T-H, Ghaffour, N & Shon, HK 2019, 'The effect of Schiff base network on the separation performance of thin film nanocomposite forward osmosis membranes', Separation and Purification Technology, vol. 217, pp. 284-293.
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© 2019 Elsevier B.V. In this study, Schiff base network-1 (SNW-1) nanoparticles, which are covalent organic frameworks (COFs), were used as fillers in the polyamide (PA) active layer to elevate the performance of thin-film nanocomposite (TFN) forward osmosis (FO) membranes. The TFN membranes were prepared by interfacial polymerization (IP) of m-phenylenediamine (MPD) and trimesoyl chloride (TMC), and the SNW-1 nanoparticles were dispersed in the MPD aqueous solution at various concentrations. The secondary amine groups of SNW-1 nanoparticles reacted with the acyl chloride groups of TMC during the IP reaction to form strong covalent/amide bonds, which facilitated better interface integration of SNW-1 nanoparticles in the PA layer. Additionally, the incorporation of amine-rich SNW-1 nanoparticles into the TFN membranes improved their surface hydrophilicity, and the porous structure of SNW-1 nanoparticles offered additional channels for transport of water molecules. The TFN0.005 membrane with a SNW-1 nanoparticle loading of 0.005 wt% demonstrated a higher water flux than that of pristine TFC membrane in both AL-FS (12.0 vs. 9.3 L m−2 h−1) and AL-DS (25.2 vs. 19.4 L m−2 h−1) orientations when they were tested with deionized water and 0.5 M NaCl as feed and draw solution, respectively.
Akther, N, Phuntsho, S, Chen, Y, Ghaffour, N & Shon, HK 2019, 'Recent advances in nanomaterial-modified polyamide thin-film composite membranes for forward osmosis processes', Journal of Membrane Science, vol. 584, pp. 20-45.
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© 2019 Elsevier B.V. Polyamide thin-film composite (PA TFC)membranes have attained much attention for forward osmosis (FO)applications in separation processes, water and wastewater treatment due to their superior intrinsic properties, such as high salt rejection and water permeability compared to the first-generation cellulose-based FO membranes. Nonetheless, several problems like fouling and trade-off between membrane selectivity and water permeability have hindered the progress of conventional PA TFC FO membranes for real applications. To overcome these issues, nanomaterials or chemical additives have been integrated into the TFC membranes. Nanomaterial-modified membranes have demonstrated significant improvement in their anti-fouling properties and FO performance. In addition, the PA TFC membranes can be designed for specific applications like heavy metal removal and osmotic membrane bioreactor by using nanomaterials to modify their physicochemical properties (porosity, surface charge, hydrophilicity, membrane structure and mechanical strength). This review provides a comprehensive summary of the progress of nanocomposite PA TFC membrane since its first development for FO in the year 2012. The nanomaterial-incorporated TFC membranes are classified into four categories based on the location of nanomaterial in/on the membranes: embedded inside the PA active layer, incorporated within the substrate, coated on the PA layer surface, or deposited as an interlayer between the substrate and the PA active layer. The key challenges still being confronted and the future research directions for nanocomposite PA TFC FO are also discussed.
Alamdari, MM, Dang Khoa, NL, Wang, Y, Samali, B & Zhu, X 2019, 'A multi-way data analysis approach for structural health monitoring of a cable-stayed bridge', Structural Health Monitoring, vol. 18, no. 1, pp. 35-48.
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A large-scale cable-stayed bridge in the state of New South Wales, Australia, has been extensively instrumented with an array of accelerometer, strain gauge, and environmental sensors. The real-time continuous response of the bridge has been collected since July 2016. This study aims at condition assessment of this bridge by investigating three aspects of structural health monitoring including damage detection, damage localization, and damage severity assessment. A novel data analysis algorithm based on incremental multi-way data analysis is proposed to analyze the dynamic response of the bridge. This method applies incremental tensor analysis for data fusion and feature extraction, and further uses one-class support vector machine on this feature to detect anomalies. A total of 15 different damage scenarios were investigated; damage was physically simulated by locating stationary vehicles with different masses at various locations along the span of the bridge to change the condition of the bridge. The effect of damage on the fundamental frequency of the bridge was investigated and a maximum change of 4.4% between the intact and damage states was observed which corresponds to a small severity damage. Our extensive investigations illustrate that the proposed technique can provide reliable characterization of damage in this cable-stayed bridge in terms of detection, localization and assessment. The contribution of the work is threefold; first, an extensive structural health monitoring system was deployed on a cable-stayed bridge in operation; second, an incremental tensor analysis was proposed to analyze time series responses from multiple sensors for online damage identification; and finally, the robustness of the proposed method was validated using extensive field test data by considering various damage scenarios in the presence of environmental variabilities.
Al-Amin Hoque, M, Billah, MM & Pradhan, B 2019, 'Spatio-temporal and demographic distribution of lightning related casualties in northeastern part of Bangladesh', International Journal of Disaster Risk Reduction, vol. 38, pp. 101197-101197.
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© 2019 Lightning is one of the frequent catastrophic hazards to people and properties across the world. Bangladesh is one of the major lightning prone countries in the world. Information regarding the spatial, temporal and demographic distribution of lightning casualties is required to develop mitigation policies to minimize the impacts of lightning. This study aims to analyse the spatial, temporal and demographic distribution of lightning-related casualties in the northeastern part of Bangladesh from 2016 to 2018. The database of lightning casualties was developed from a variety of sources including government and private agencies. Records dating from 2016 to 2018 indicate that about 78 and 60 people have been killed and injured, respectively by lightning strikes. The highest number of lightning fatalities were reported in the districts of Kishoreganj (31%), Habiganj (18%) and Sunamganj (15%). The overall fatality rate is 1.76 per million people per year, and fatality density rate is 0.00388 per million people km−2 year−1. The majority of fatalities and injuries occurred within the early morning 0800 and early evening 1700 at local time. The number of fatalities was higher in April–May during the pre-monsoon season. The maximum number of people died by lightning during farming activities, followed by fishing, boating or bathing in water bodies. The findings of the study are highly beneficial to the administrator and policymakers to develop lightning mitigation plans, improve public awareness and lightning safety campaign to reduce the impacts of lightning hazards.
Alazigha, DP, Vinod, JS, Indraratna, B & Heitor, A 2019, 'Potential use of lignosulfonate for expansive soil stabilisation', Environmental Geotechnics, vol. 6, no. 7, pp. 480-488.
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This study involved the laboratory evaluation of the effectiveness of lignosulfonate (LS) admixture in improving engineering properties (i.e. swell potential, unconfined compressive strength, durability, compaction characteristics, permeability, consolidation characteristics and shrinkage behaviour) of a remoulded expansive soil. Standard geotechnical laboratory tests performed on untreated and LS-treated soil specimens compacted at optimum moisture content and maximum dry unit weight showed significant and consistent improvements in the engineering properties of the soil. The swell potential of the soil decreased by 23% while maintaining its ductility and pH value. The improved soil resistance to repeated freeze–thaw/wet–dry cycles was also observed in the LS-treated specimens. Likewise, the compressive strength, consolidation characteristics and shrinkage limit improved appreciably. However, the compaction characteristics and permeability of the treated soil remained relatively unchanged. With over 50 Mt of global annual production of LS, the successful use of LS as an alternative admixture for expansive soil stabilisation provides viable solutions to the sustainable use of the lignin by-products from paper manufacturing industry.
Ali, SM, Qamar, A, Kerdi, S, Phuntsho, S, Vrouwenvelder, JS, Ghaffour, N & Shon, HK 2019, 'Energy efficient 3D printed column type feed spacer for membrane filtration', Water Research, vol. 164, pp. 114961-114961.
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© 2019 Elsevier Ltd Modification of the feed spacer design significantly influences the energy consumption of membrane filtration processes. This study developed a novel column type feed spacer with the aim to reduce the specific energy consumption (SEC) of the membrane based water filtration system. The proposed spacer increases the clearance between the filament and the membrane (reducing the spacer filament diameter) while keeping the same flow channel thickness as compared to a standard non-woven symmetric spacer. Since the higher clearance reduces the flow unsteadiness, column type nodes were added in the spacer structure as additional vortex shading bodies. Fluid flow behaviour in the channel for this spacer was numerically simulated by 3D CFD studies and then compared with the standard spacer. The numerical results showed that the proposed spacer substantially reduced the pressure drop, shear stress at the constriction region and shortened the dead zone. Finally, these findings were confirmed experimentally by investigating the filtration performances using the 3D printed prototypes of these spacers in a lab-scale filtration module. It is observed that the column spacer reduced the pressure drop by three times and doubled the specific water flux. 2D OCT (Optical Coherence Tomography) scans of the membrane surface acquired after the filtration revealed much lower biomass accumulation using the proposed spacer. Consequently, the SEC for the column spacer was found about two folds lower than the standard spacer.
Alilou, H, Rahmati, O, Singh, VP, Choubin, B, Pradhan, B, Keesstra, S, Ghiasi, SS & Sadeghi, SH 2019, 'Evaluation of watershed health using Fuzzy-ANP approach considering geo-environmental and topo-hydrological criteria', Journal of Environmental Management, vol. 232, pp. 22-36.
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Assessment of watershed health and prioritization of sub-watersheds are needed to allocate natural resources and efficiently manage watersheds. Characterization of health and spatial prioritization of sub-watersheds in data scarce regions helps better comprehend real watershed conditions and design and implement management strategies. Previous studies on the assessment of health and prioritization of sub-watersheds in ungauged regions have not considered environmental factors and their inter-relationship. In this regard, fuzzy logic theory can be employed to improve the assessment of watershed health. The present study considered a combination of climate vulnerability (Climate Water Balance), relative erosion rate of surficial rocks, slope weighted K-factor, topographic indices, thirteen morphometric characteristics (linear, areal, and relief aspects), and potential non-point source pollution to assess watershed health, using a new framework which considers the complex linkage between human activities and natural resources. The new framework, focusing on watershed health score (WHS), was employed for the spatial prioritization of 31 sub-watersheds in the Khoy watershed, West Azerbaijan Province, Iran. In this framework, an analytical network process (ANP) and fuzzy theory were used to investigate the inter-relationships between the above mentioned geo-environmental factors and to classify and rank the health of each sub-watershed in four classes. Results demonstrated that only one sub-watershed (C15) fell into the class that was defined as 'a potentially critical zone'. This article provides a new framework and practical recommendations for watershed management agencies with a high level of assurance when there is a lack of reliable hydrometric gauge data.
Almabrok, MH, McLaughlan, R, Vessalas, K & Thomas, P 2019, 'Effect of oil contaminated aggregates on cement hydration', American Journal of Engineering Research (AJER), vol. 8, no. 5, pp. 81-89.
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Canola oil, refined mineral oil, and crude oil additions up to 10% of the aggregate mass inPortland cement mortars were found to decrease the 28-day compressive strength by 71%, 75% and 50%,respectively, and retard setting times. There was a progressive impact upon cement hydration as the oil contentincreased in mortars. Only in the case of vegetable oil and refined mineral oil could strength loss be attributedin part to cement hydration inhibition, as evidenced by reduced total evolved heat. It is likely thatmicrostructural effects were also a key factor in strength loss for all mortars particularly for those containingcrude oil.
Al-Muhsen, NFO, Huang, Y & Hong, G 2019, 'Effects of direct injection timing associated with spark timing on a small spark ignition engine equipped with ethanol dual-injection', Fuel, vol. 239, pp. 852-861.
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© 2018 Elsevier Ltd Dual injection of ethanol fuel (DualEI) has been in development. DualEI has the potential in increasing the compression ratio and thermal efficiency of spark ignition engines by taking the advantages of ethanol fuel properties and the direct injection. This paper reports an experimental investigation of the effect of direct injection (DI) timing associated with spark timing on the performance of a small DualEI engine. Experiments were conducted with fixed port injection timing and varied DI timing before (early) and after (late) the intake valve closed at 3500 RPM and two load conditions. Results show that the engine performance is enhanced by early DI timing, although the variation of IMEP and indicated thermal efficiency with DI timing is not significant either with early DI timing or in most of the tested conditions with late DI timing. Only in the medium load condition when the DI timing is retarded from 80 to 60 CAD bTDC, the IMEP and thermal efficiency significantly reduced by about 16% due to the increased initial combustion duration, resulting in reduced flame speed and increased combustion instability. The results also show different effects of early and late DI timing associated with the spark timing on engine emissions. With late DI timing, the engine emissions of CO and NO increase with the advance of late DI timing and spark timing. With early DI timing, the engine emissions increase with the advance of spark timing. However, the variation of engine emissions with early DI timing is more complicated than that late.
Al-Najjar, HAH, Kalantar, B, Pradhan, B, Saeidi, V, Halin, AA, Ueda, N & Mansor, S 2019, 'Land Cover Classification from fused DSM and UAV Images Using Convolutional Neural Networks', Remote Sensing, vol. 11, no. 12, pp. 1461-1461.
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In recent years, remote sensing researchers have investigated the use of different modalities (or combinations of modalities) for classification tasks. Such modalities can be extracted via a diverse range of sensors and images. Currently, there are no (or only a few) studies that have been done to increase the land cover classification accuracy via unmanned aerial vehicle (UAV)–digital surface model (DSM) fused datasets. Therefore, this study looks at improving the accuracy of these datasets by exploiting convolutional neural networks (CNNs). In this work, we focus on the fusion of DSM and UAV images for land use/land cover mapping via classification into seven classes: bare land, buildings, dense vegetation/trees, grassland, paved roads, shadows, and water bodies. Specifically, we investigated the effectiveness of the two datasets with the aim of inspecting whether the fused DSM yields remarkable outcomes for land cover classification. The datasets were: (i) only orthomosaic image data (Red, Green and Blue channel data), and (ii) a fusion of the orthomosaic image and DSM data, where the final classification was performed using a CNN. CNN, as a classification method, is promising due to hierarchical learning structure, regulating and weight sharing with respect to training data, generalization, optimization and parameters reduction, automatic feature extraction and robust discrimination ability with high performance. The experimental results show that a CNN trained on the fused dataset obtains better results with Kappa index of ~0.98, an average accuracy of 0.97 and final overall accuracy of 0.98. Comparing accuracies between the CNN with DSM result and the CNN without DSM result for the overall accuracy, average accuracy and Kappa index revealed an improvement of 1.2%, 1.8% and 1.5%, respectively. Accordingly, adding the heights of features such as buildings and trees improved the differentiation between vegetation specifically where plants wer...
Altaee, A & Cipolina, A 2019, 'Modelling and optimization of modular system for power generation from a salinity gradient', Renewable Energy, vol. 141, pp. 139-147.
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© 2019 Elsevier Ltd Pressure retarded osmosis has been proposed for power generation from a salinity gradient resource. The process has been promoted as a promising technology for power generation from renewable resources, but most of the experimental work has been done on a laboratory size units. To date, pressure retarded osmosis optimization and operation is based on parametric studies performed on laboratory scale units, which leaves a gap in our understanding of the process behaviour in a full-scale modular system. A computer model has been developed to predict the process performance. Process modelling was performed on a full-scale membrane module and impact of key operating parameters such as hydraulic feed pressure and feed and draw solution rates were evaluated. Results showed that the optimum fraction of feed/draw solution in a mixture is less than what has been earlier proposed ratio of 50% and it is entirely dependent on the salinity gradient resource concentration. Furthermore, the optimized pressure retarded osmosis process requires a hydraulic pressure less than that in the normal (unoptimized) process. The results here demonstrate that the energy output from the optimized pressure regarded osmosis process is up to 54% higher than that in the normal (unoptimized) process.
Altaee, A, Braytee, A, Millar, GJ & Naji, O 2019, 'Energy efficiency of hollow fibre membrane module in the forward osmosis seawater desalination process', Journal of Membrane Science, vol. 587, pp. 117165-117165.
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© 2019 This study provided new insights regarding the energy efficiency of hollow fibre forward osmosis modules for seawater desalination; and as a consequence an approach was developed to improve the process performance. Previous analysis overlooked the relationship between the energy efficiency and operating modes of the hollow fibre forward osmosis membrane when the process was scaled-up. In this study, the module length and operating parameters were incorporated in the design of an energy-efficient forward osmosis system. The minimum specific power consumption for seawater desalination was calculated at the thermodynamic limits. Two FO operating modes: (1) draw solution in the lumen and (2) feed solution in the lumen, were evaluated in terms of the desalination energy requirements at a minimum draw solution flow rate. The results revealed that the operating mode of the forward osmosis membrane was important in terms of reducing the desalination energy. In addition, the length of the forward osmosis module was also a significant factor and surprisingly increasing the length of the forward osmosis module was not always advantageous in improving the performance. The study outcomes also showed that seawater desalination by the forward osmosis process was less energy efficient at low and high osmotic draw solution concentration and performed better at 1.2–1.4 M sodium chloride draw solution concentrations. The findings of this study provided a platform to the manufacturers and operators of hollow fibre forward osmosis membrane to improve the energy efficiency of the desalination process.
Altaee, A, Zhou, J, Zaragoza, G & Sharif, AO 2019, 'Impact of membrane orientation on the energy efficiency of dual stage pressure retarded osmosis', Journal of Water Process Engineering, vol. 30, pp. 100621-100621.
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© 2018 Elsevier Ltd The performance of Dual Stage Pressure Retarded Osmosis (DSPRO) was analyzed using a developed computer model. DSPRO process was evaluated on Pressure Retarded Osmosis (PRO) and Forward Osmosis (FO) operating modes for different sodium chloride (NaCl) draw and feed concentrations. Simulation results revealed that the total power generation in the DSPRO process operating on the PRO mode was 2.5–5 times more than that operating on the FO mode. For DSPRO operating on the PRO mode, the higher power generation was in the case of 2 M NaCl-fresh and 32% the contribution of the second stage to the total power generation in the DSPRO. To the contrast, he total power generated in the DSPRO operating on the FO mode was in the following order 5M-0.6M > 5M-0.7M > 2M-0.01 > 2M-0.6 M. Interestingly, single stage process operating on the FO mode performed better than DSPRO process due to the severe concentration polarization effects. The results also showed that power density of the DSPRO reached a maximum amount at a hydraulic pressure less than the average osmotic pressure gradient, Δπ/2, due to the variation of optimum operating pressure of each stage. Moreover, results showed that the effective specific energy in the PRO process was lower than the maximum specific energy. However, the effective specific energy of the DSPRO was larger than that of the single stage PRO due to the rejuvenation of the salinity gradient, emphasizing the high potential of the DSPRO process for power generation.
Alterman, D, Stewart, MG & Netherton, MD 2019, 'Probabilistic assessment of airblast variability and fatality risk estimation for explosive blasts in confined building spaces', International Journal of Protective Structures, vol. 10, no. 3, pp. 306-329.
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Explosive blasts in confined building spaces, such as lobbies or foyers, can amplify blast loads. This article uses the computational fluid dynamics model ProsAir to estimate blast loads in a typical ground floor lobby of a commercial or government building. Monte-Carlo simulation is used to probabilistically model the effect that variability and uncertainty of charge mass and location, net equivalent quantity factor, temperature, atmospheric pressure and model errors have on airblast variability. The analysis then calculates the probability of casualties due to the effects of pressure and impulse, where human vulnerability due to the effects of pressure and impulse is a function of lung rupture, whole-body displacement or skull fracture (or the combination of the three). The terrorist threats considered are improvised explosive devices ranging in mass from 5 kg (backpack bomb) to 23 kg (suitcase bomb) detonated in various locations inside the building. As expected, blast pressure and fatality risks are dependent on the type of facade glazing (e.g. vulnerable glazing allows venting of the blast), improvised explosive device size and location. It was found that the mean fatality risk for a 23 kg terrorist improvised explosive device is 8.6%, but there is a 5% chance that fatality risks can exceed 20%. It was also found that a probabilistic analysis yielded lower mean fatality risks than a deterministic analysis. The effect of venting was also significant. Mean fatality risks increased by up to 10-fold if there was no venting (i.e. a bunker-like structure without windows), but reduced by about 30% for a fully vented structure (i.e. no windows). This probabilistic analysis allows decision-makers to be more aware of terrorism risks to building occupants, and how improved building design and security measures may ameliorate these risks.
An, Z, Dai, Y, Jiang, Y & He, J 2019, 'Asymmetric Knoevenagel‐Phospha‐Michael Tandem Reaction Synergistically Catalyzed by Achiral Silanols and Grafted Chiral Amines on Mesoporous Silica', Asian Journal of Organic Chemistry, vol. 8, no. 8, pp. 1539-1547.
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AbstractHighly efficient and enantioselective asymmetric Knoevenagel‐phospha‐Michael tandem reactions have been achieved on bifunctional heterogeneous catalysts with inherent silanols as acidic sites and immobilized chiral amines as basic sites. Final products were afforded in yields of up to 99% and ee values of up to 99%. The effects of substituents on benzaldehyde and molecular dimensions of phosphites have also been investigated. Larger substrates can access the catalytic site inside larger mesoporous pores, thereby improving both of yield and ee of final products.
Anis, Z, Wissem, G, Riheb, H, Biswajeet, P & Mohamed Essghaier, G 2019, 'Effects of clay properties in the landslides genesis in flysch massif: Case study of Aïn Draham, North Western Tunisia', Journal of African Earth Sciences, vol. 151, pp. 146-152.
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© 2018 Elsevier Ltd Heavy rainfall in Aïn Draham province in the North-Western of Tunisia lead to the formation of some landslides which could poses danger to lives and properties. The geological outcrops of the region mainly consist of Numidian flysch rocks. In this study, field based 15 undisturbed samples were taken, from 11 boreholes drilled in 4 landslide points, to understand the real behaviour of soils when landslides occur. For this purpose, the geotechnical characterization of all samples was carried out. The grain size distribution shows that the clay and silt fractions prevail. The clay fraction ranges between 4% and 64% with an average of 40.4%, the silt fraction ranging from 19% to 71% averaging 39.8% and the sand fraction was between 6% and 44% with an average of 19.8%. The Casagrande plasticity chart indicates that 33.3% of samples were in the high plasticity group (CH group) and 66.6% having a medium to low plasticity. The water content varies between 12% and 31%. The direct shear strength test shows that the cohesions values range from 41 KPa to 77 KPa and the internal friction angle values range widely from 12° to 27°. A statistical approach was taken to determine the most important factors responsible for the decrease of the cohesion and friction angle which are in charge of slope failure. For this, a correlation matrix of all soil properties was done. The coefficients of correlation show that the clay fraction is the most correlated parameter to the cohesion with an index of −0.872. Unfortunately, the internal friction angle is very low correlated to all geotechnical parameters. The clay fraction, as the most correlated to the cohesion, and the water content, which depends on rainfall (landslide triggering factor), were considered as two independent parameters for the establishment of a multiple linear and non-linear regression models of the cohesion. The multiple linear model showed that the cohesion decrease with the increase of water conten...
Arabameri, A, Chen, W, Blaschke, T, Tiefenbacher, JP, Pradhan, B & Tien Bui, D 2019, 'Gully Head-Cut Distribution Modeling Using Machine Learning Methods—A Case Study of N.W. Iran', Water, vol. 12, no. 1, pp. 16-16.
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To more effectively prevent and manage the scourge of gully erosion in arid and semi-arid regions, we present a novel-ensemble intelligence approach—bagging-based alternating decision-tree classifier (bagging-ADTree)—and use it to model a landscape’s susceptibility to gully erosion based on 18 gully-erosion conditioning factors. The model’s goodness-of-fit and prediction performance are compared to three other machine learning algorithms (single alternating decision tree, rotational-forest-based alternating decision tree (RF-ADTree), and benchmark logistic regression). To achieve this, a gully-erosion inventory was created for the study area, the Chah Mousi watershed, Iran by combining archival records containing reports of gully erosion, remotely sensed data from Google Earth, and geolocated sites of gully head-cuts gathered in a field survey. A total of 119 gully head-cuts were identified and mapped. To train the models’ analysis and prediction capabilities, 83 head-cuts (70% of the total) and the corresponding measures of the conditioning factors were input into each model. The results from the models were validated using the data pertaining to the remaining 36 gully locations (30%). Next, the frequency ratio is used to identify which conditioning-factor classes have the strongest correlation with gully erosion. Using random-forest modeling, the relative importance of each of the conditioning factors was determined. Based on the random-forest results, the top eight factors in this study area are distance-to-road, drainage density, distance-to-stream, LU/LC, annual precipitation, topographic wetness index, NDVI, and elevation. Finally, based on goodness-of-fit and AUROC of the success rate curve (SRC) and prediction rate curve (PRC), the results indicate that the bagging-ADTree ensemble model had the best performance, with SRC (0.964) and PRC (0.978). RF-ADTree (SRC = 0.952 and PRC = 0.971), ADTree (SRC = 0.926 and PRC = 0.965), and LR (SRC = ...
Arabameri, A, Pradhan, B & Lombardo, L 2019, 'Comparative assessment using boosted regression trees, binary logistic regression, frequency ratio and numerical risk factor for gully erosion susceptibility modelling', CATENA, vol. 183, pp. 104223-104223.
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© 2019 Elsevier B.V. The initiation and development of gullies as worldwide features in landscape have resulted in land degradation, soil erosion, desertification, flooding and groundwater level decrease, which in turn, cause severe destruction to infrastructure. Gully erosion susceptibility mapping is the first and most important step in managing these effects and achieving sustainable development. This paper attempts to generate a reliable map using four state-of-the-art models to investigate the Bayazeh Watershed in Iran. These models consists of boosted regression trees (BRT), binary logistic regression (BLR), numerical risk factor (NRF) and frequency ratio (FR), which are based on a geographic information system (GIS). The gully erosion inventory map accounts for 362 gully locations, which were randomly divided into two groups (70% for training and 30% for validation). Sixteen topographical, geological, hydrological and environmental gully-related conditioning factors were selected for modelling. The threshold-independent area under receiver operating characteristic (AUROC) and seed cell area index (SCAI) approaches were used for validation. According to the results of BLR and BRT, the conditioning parameters namely, NDVI and lithology, played a key role in gully occurrence. Validation results showed that the BRT model with AUROC = 0.834 (83.4%) had higher prediction accuracy than other models, followed by FR 0.823 (82.3%), NRF 0.746 (74.6%) and BLR 0.659 (65.9%). SCAI results indicated that the BRT, FR and BLR models had acceptable classification accuracy. The findings, in terms of model and predictor choice, can be used by decision-makers for hazard management and implementation of protective measures in gully erosion-prone areas.
Arabameri, A, Pradhan, B & Rezaei, K 2019, 'Gully erosion zonation mapping using integrated geographically weighted regression with certainty factor and random forest models in GIS', Journal of Environmental Management, vol. 232, pp. 928-942.
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© 2018 Elsevier Ltd Every year, gully erosion causes substantial damage to agricultural land, residential areas and infrastructure, such as roads. Gully erosion assessment and mapping can facilitate decision making in environmental management and soil conservation. Thus, this research aims to propose a new model by combining the geographically weighted regression (GWR) technique with the certainty factor (CF) and random forest (RF) models to produce gully erosion zonation mapping. The proposed model was implemented in the Mahabia watershed of Iran, which is highly sensitive to gully erosion. Firstly, dependent and independent variables, including a gully erosion inventory map (GEIM) and gully-related causal factors (GRCFs), were prepared using several data sources. Secondly, the GEIM was randomly divided into two groups: training (70%) and validation (30%) datasets. Thirdly, tolerance and variance inflation factor indicators were used for multicollinearity analysis. The results of the analysis corroborated that no collinearity exists amongst GRCFs. A total of 12 topographic, hydrologic, geologic, climatologic, environmental and soil-related GRCFs and 150 gully locations were used for modelling. The watershed was divided into eight homogeneous units because the importance level of the parameters in different parts of the watershed is not the same. For this purpose, coefficients of elevation, distance to stream and distance to road parameters were used. These coefficients were obtained by extracting bi-square kernel and AIC via the GWR method. Subsequently, the RF-CF integrated model was applied in each unit. Finally, with the units combined, the final gully erosion susceptibility map was obtained. On the basis of the RF model, distance to stream, distance to road and land use/land cover exhibited a high influence on gully formation. Validation results using area under curve indicated that new GWR–CF–RF approach has a higher predictive accuracy 0.967 (96....
Arabameri, A, Pradhan, B & Rezaei, K 2019, 'Spatial prediction of gully erosion using ALOS PALSAR data and ensemble bivariate and data mining models', Geosciences Journal, vol. 23, no. 4, pp. 669-686.
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© 2019, The Association of Korean Geoscience Societies and Springer. Remote sensing is recognized as a powerful and efficient tool that provides a comprehensive view of large areas that are difficult to access, and also reduces costs and shortens the timing of projects. The purpose of this study is to introduce effective parameters using remote sensing data and subsequently predict gully erosion using statistical models of Density Area (DA) and Information Value (IV), and data mining based Random Forest (RF) model and their ensemble. The aforementioned models were employed at the Tororud-Najarabad watershed in the northeastern part of Semnan province, Iran. For this purpose, at first using various resources, the map of the distribution of the gullies was prepared with the help of field visits and Google Earth images. In order to analyse the earth’s surface and extraction of topographic parameters, a digital elevation model derived from PALSAR (Phased Array type L-band Synthetic Aperture Radar) radar data with a resolution of 12.5 meters was used. Using literature review, expert opinion and multi-collinearity test, 15 environmental parameters were selected with a resolution of 12.5 meters for the modelling. Results of RF model indicate that parameters of NDVI (normalized difference vegetation index), elevation and land use respectively had the highest effect on the gully erosion. Several techniques such as area under curve (AUC), seed cell area index (SCAI), and Kappa coefficient were used for validation. Results of validation indicated that the combination of bivariate (IV and DA models) with the RF data-mining model has increased their performance. The prediction accuracy of AUC and Kappa values in DA, IV and RF are (0.745, 0.782, and 0.792) and (0.804, 0.852, and 0.860) and these values in ensemble models of DA-RF and IV-RF are (0.845, and 0.911) and (0.872, and 0.951) respectively. Results of SCAI show that ensemble models had a good performance, so that, with...
Arabameri, A, Pradhan, B, Rezaei, K & Conoscenti, C 2019, 'Gully erosion susceptibility mapping using GIS-based multi-criteria decision analysis techniques', CATENA, vol. 180, pp. 282-297.
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© 2019 Elsevier B.V. This research introduces a scientific methodology for gully erosion susceptibility mapping (GESM)that employs geography information system (GIS)-based multi-criteria decision analysis. The model was tested in Semnan Province, Iran, which has an arid and semi-arid climate with high susceptibility to gully erosion. The technique for order of preference by similarity to ideal solution (TOPSIS)and the analytic hierarchy process (AHP)multi-criteria decision-making (MCDM)models were integrated. The important aspect of this research is that it did not require gully erosion inventory maps for GESM. Therefore, the proposed methodology could be useful in areas with missing or incomplete data. Fifteen variables reflecting topographic, hydrologic, geologic, environmental and soil characteristics were selected as proxies for gully erosion conditioning factors (GECFs). The experiment was conducted using 200 sample points that were selected randomly in the study area, and the weights of criteria (GECFs)were obtained using the AHP model. In the next step, the TOPSIS model was applied, and the weight of each alternative (sample points)was obtained. Kriging and inverse distance-weighted (IDW)methods were used for interpolation and GESM. Natural break method was used for classifying gully erosion susceptibility into five classes, from very low to very high. The area under the ROC curve (AUC)was used for validation. AHP results showed that distance to stream (0.14), slope degree (0.13)and distance to road (0.12)played major roles in controlling gully erosion in the study area. The values of points obtained by using the TOPSIS model ranged from 0.321 to 0.808. Verification results showed that kriging had higher prediction accuracy than IDW. The GESM results obtained by this methodology can be used by decision makers and managers to plan preventive measures and reduce damages due to gully erosion.
Arabameri, A, Pradhan, B, Rezaei, K, Sohrabi, M & Kalantari, Z 2019, 'GIS-based landslide susceptibility mapping using numerical risk factor bivariate model and its ensemble with linear multivariate regression and boosted regression tree algorithms', Journal of Mountain Science, vol. 16, no. 3, pp. 595-618.
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© 2019, Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany, part of Springer Nature. In this study, a novel approach of the landslide numerical risk factor (LNRF) bivariate model was used in ensemble with linear multivariate regression (LMR) and boosted regression tree (BRT) models, coupled with radar remote sensing data and geographic information system (GIS), for landslide susceptibility mapping (LSM) in the Gorganroud watershed, Iran. Fifteen topographic, hydrological, geological and environmental conditioning factors and a landslide inventory (70%, or 298 landslides) were used in mapping. Phased array-type L-band synthetic aperture radar data were used to extract topographic parameters. Coefficients of tolerance and variance inflation factor were used to determine the coherence among conditioning factors. Data for the landslide inventory map were obtained from various resources, such as Iranian Landslide Working Party (ILWP), Forestry, Rangeland and Watershed Organisation (FRWO), extensive field surveys, interpretation of aerial photos and satellite images, and radar data. Of the total data, 30% were used to validate LSMs, using area under the curve (AUC), frequency ratio (FR) and seed cell area index (SCAI). Normalised difference vegetation index, land use/ land cover and slope degree in BRT model elevation, rainfall and distance from stream were found to be important factors and were given the highest weightage in modelling. Validation results using AUC showed that the ensemble LNRF-BRT and LNRFLMR models (AUC = 0.912 (91.2%) and 0.907 (90.7%), respectively) had high predictive accuracy than the LNRF model alone (AUC = 0.855 (85.5%)). The FR and SCAI analyses showed that all models divided the parameter classes with high precision. Overall, our novel approach of combining multivariate and machine learning methods with bivariate models, radar remote sensing data and GIS proved to be a powerful tool for landslid...
Arabameri, A, Yamani, M, Pradhan, B, Melesse, A, Shirani, K & Tien Bui, D 2019, 'Novel ensembles of COPRAS multi-criteria decision-making with logistic regression, boosted regression tree, and random forest for spatial prediction of gully erosion susceptibility', Science of The Total Environment, vol. 688, pp. 903-916.
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Gully erosion is considered as a severe environmental problem in many areas of the world which causes huge damages to agricultural lands and infrastructures (i.e. roads, buildings, and bridges); however, gully erosion modeling and prediction with high accuracy are still difficult due to the complex interactions of various factors. The objective of this research was to develop and introduce three new ensemble models, which were based on Complex Proportional Assessment of Alternatives (COPRAS), Logistic Regression (LR), Boosted Regression Tree (BRT), Random Forest (RF), and Frequency Ratio (FR) for spatial prediction of gully erosion with a case study at the Najafabad watershed (Iran). For this purpose, a total of 290 head-cut of gullies and 17 conditioning factors were collected and used to establish a geospatial database. Subsequently, FR was used to determine the spatial relationship between the conditioning factors and the head-cut of gullies, whereas RF, BRT, and LR were used to quantify the relative importance of these factors. In the next step, three ensemble gully erosion models, named COPRAS-FR-RF, COPRAS-FR-BRT, and COPRAS-FR-LR were developed and verified. The Success Rate Curve (SRC), and the Prediction Rate Curve (PRC) and their areas under the curves (AUC) were used to check the performance of the three proposed models. The result showed that Soil group, geomorphology, and drainage density factors played the key role on the occurrence of the gully erosion. All the three models have very high degree-of-fit and the prediction performance, the COPRAS-FR-RF model (AUC-SRC = 0.974 and AUC-PRC = 0.929), the COPRAS-FR-BRT model (AUC-SRC = 0.973 and AUC-PRC = 0.928), and the COPRAS-FR-LR model (AUC-SRC = 0.972 and AUC-PRC = 0.926); therefore, it is concluded that they are efficient and new powerful tools which could be used for predicting gully erosion in prone-areas.
Arabameri, Cerda, Rodrigo-Comino, Pradhan, Sohrabi, Blaschke & Tien Bui 2019, 'Proposing a Novel Predictive Technique for Gully Erosion Susceptibility Mapping in Arid and Semi-arid Regions (Iran)', Remote Sensing, vol. 11, no. 21, pp. 2577-2577.
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Gully erosion is considered to be one of the main causes of land degradation in arid and semi-arid territories around the world. In this research, gully erosion susceptibility mapping was carried out in Semnan province (Iran) as a case study in which we tested the efficiency of the index of entropy (IoE), the Vlse Kriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method, and their combination. Remote sensing and geographic information system (GIS) were used to reduce the time and costs needed for rapid assessment of gully erosion. Firstly, a gully erosion inventory map (GEIM) with 206 gully locations was obtained from various sources and randomly divided into two groups: A training dataset (70% of the data) and a validation dataset (30% of the data). Fifteen gully-related conditioning factors (GRCFs) including elevation, slope, aspect, plan curvature, stream power index, topographical wetness index, rainfall, soil type, drainage density, distance to river, distance to road, distance to fault, lithology, land use/land cover, and soil type, were used for modeling. The advanced land observing satellite (ALOS) digital elevation model with a spatial resolution of 30 m was used for the extraction of the above-mentioned topographic factors. The tolerance (TOL) and variance inflation factor (VIF) were also included for checking the multicollinearity among the GRCFs. Based on IoE, we concluded that soil type, lithology, and elevation were the most significant in terms of gully formation. Validation results using the area under the receiver operating characteristic curve (AUROC) showed that IoE (0.941) reached a higher prediction accuracy than VIKOR (0.857) and VIKOR-IoE (0.868). Based on our results, the combination of statistical (IoE) models along with remote sensing and GIS can convert the multi-criteria decision-making (MCDM) models into efficient and powerful tools for gully erosion prediction. We strongly suggest that decision-makers and man...
Arabameri, Pradhan, Rezaei & Lee 2019, 'Assessment of Landslide Susceptibility Using Statistical- and Artificial Intelligence-based FR–RF Integrated Model and Multiresolution DEMs', Remote Sensing, vol. 11, no. 9, pp. 999-999.
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Landslide is one of the most important geomorphological hazards that cause significant ecological and economic losses and results in billions of dollars in financial losses and thousands of casualties per year. The occurrence of landslide in northern Iran (Alborz Mountain Belt) is often due to the geological and climatic conditions and tectonic and human activities. To reduce or control the damage caused by landslides, landslide susceptibility mapping (LSM) and landslide risk assessment are necessary. In this study, the efficiency and integration of frequency ratio (FR) and random forest (RF) in statistical- and artificial intelligence-based models and different digital elevation models (DEMs) with various spatial resolutions were assessed in the field of LSM. The experiment was performed in Sangtarashan watershed, Mazandran Province, Iran. The study area, which extends to 1,072.28 km2, is severely affected by landslides, which cause severe economic and ecological losses. An inventory of 129 landslides that occurred in the study area was prepared using various resources, such as historical landslide records, the interpretation of aerial photos and Google Earth images, and extensive field surveys. The inventory was split into training and test sets, which include 70 and 30% of the landslide locations, respectively. Subsequently, 15 topographic, hydrologic, geologic, and environmental landslide conditioning factors were selected as predictor variables of landslide occurrence on the basis of literature review, field works and multicollinearity analysis. Phased array type L-band synthetic aperture radar (PALSAR), ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), and SRTM (Shuttle Radar Topography Mission) DEMs were used to extract topographic and hydrologic attributes. The RF model showed that land use/land cover (16.95), normalised difference vegetation index (16.44), distance to road (15.32) and elevation (13.6) were the most...
Areerachakul, N, Sakulkhaemaruethai, S, Johir, MAH, Kandasamy, J & Vigneswaran, S 2019, 'Photocatalytic degradation of organic pollutants from wastewater using aluminium doped titanium dioxide', Journal of Water Process Engineering, vol. 27, pp. 177-184.
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Arshad, B, Ogie, R, Barthelemy, J, Pradhan, B, Verstaevel, N & Perez, P 2019, 'Computer Vision and IoT-Based Sensors in Flood Monitoring and Mapping: A Systematic Review', Sensors, vol. 19, no. 22, pp. 5012-5012.
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Floods are amongst the most common and devastating of all natural hazards. The alarming number of flood-related deaths and financial losses suffered annually across the world call for improved response to flood risks. Interestingly, the last decade has presented great opportunities with a series of scholarly activities exploring how camera images and wireless sensor data from Internet-of-Things (IoT) networks can improve flood management. This paper presents a systematic review of the literature regarding IoT-based sensors and computer vision applications in flood monitoring and mapping. The paper contributes by highlighting the main computer vision techniques and IoT sensor approaches utilised in the literature for real-time flood monitoring, flood modelling, mapping and early warning systems including the estimation of water level. The paper further contributes by providing recommendations for future research. In particular, the study recommends ways in which computer vision and IoT sensor techniques can be harnessed to better monitor and manage coastal lagoons—an aspect that is under-explored in the literature.
Ashok, B, Nanthagopal, K, Darla, S, Chyuan, OH, Ramesh, A, Jacob, A, Sahil, G, Thiyagarajan, S & Geo, VE 2019, 'Comparative assessment of hexanol and decanol as oxygenated additives with calophyllum inophyllum biodiesel', Energy, vol. 173, pp. 494-510.
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© 2019 Elsevier Ltd In this research work, the four ternary blends were prepared with 30% and 40% by volume of higher alcohol (decanol and hexanol) with biodiesel while maintain 50% of diesel concentration. All ternary blends of diesel-biodiesel-higher alcohols were used in single cylinder engine and the results were compared with binary blend of 50%–50% biodiesel, pure diesel and biodiesel. It was revealed that thermal efficiency of ternary blends was higher than biodiesel and in some cases it is closer to pure diesel. In contrary, specific fuel consumption is found to lower with increase in alcohol fractions in ternary blends. Moreover, hydrocarbon, smoke, carbon monoxide emissions from alcohol-infused fuel blends were observed to be lower than both biodiesel and pure diesel. Significant reduction in oxides of nitrogen (NOx) emissions was also observed by the addition of higher alcohols to the fuel blend when compared to biodiesel fuel. It is to be noted that decanol 40% addition with diesel and biodiesel blend has shown better results in emission characteristics. Furthermore, the heat release rate and in-cylinder pressure for biodiesel were significantly lower compared to pure diesel fuels. However, addition of 40% decanol with fuel blend improved the heat release rate and in-cylinder pressure.
Ashournejad, Q, Hosseini, A, Pradhan, B & Hosseini, SJ 2019, 'Hazard zoning for spatial planning using GIS-based landslide susceptibility assessment: a new hybrid integrated data-driven and knowledge-based model', Arabian Journal of Geosciences, vol. 12, no. 4.
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Asif, MB, Ansari, AJ, Chen, S-S, Nghiem, LD, Price, WE & Hai, FI 2019, 'Understanding the mechanisms of trace organic contaminant removal by high retention membrane bioreactors: a critical review', Environmental Science and Pollution Research, vol. 26, no. 33, pp. 34085-34100.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. High retention membrane bioreactors (HR-MBR) combine a high retention membrane separation process such as membrane distillation, forward osmosis, or nanofiltration with a conventional activated sludge (CAS) process. Depending on the physicochemical properties of the trace organic contaminants (TrOCs) as well as the selected high retention membrane process, HR-MBR can achieve effective removal (80–99%) of a broad spectrum of TrOCs. An in-depth assessment of the available literature on HR-MBR performance suggests that compared to CAS and conventional MBRs (using micro- or ultra-filtration membrane), aqueous phase removal of TrOCs in HR-MBR is significantly better. Conceptually, longer retention time may significantly improve TrOC biodegradation, but there are insufficient data in the literature to evaluate the extent of TrOC biodegradation improvement by HR-MBR. The accumulation of hardly biodegradable TrOCs within the bioreactor of an HR-MBR system may complicate further treatment and beneficial reuse of sludge. In addition to TrOCs, accumulation of salts gradually increases the salinity in bioreactor and can adversely affect microbial activities. Strategies to mitigate these limitations are discussed. A qualitative framework is proposed to predict the contribution of the different key mechanisms of TrOC removal (i.e., membrane retention, biodegradation, and sorption) in HR-MBR.
Aslani, F, Hou, L, Nejadi, S, Sun, J & Abbasi, S 2019, 'Experimental analysis of fiber‐reinforced recycled aggregate self‐compacting concrete using waste recycled concrete aggregates, polypropylene, and steel fibers', Structural Concrete, vol. 20, no. 5, pp. 1670-1683.
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AbstractSelf‐compacting concrete (SCC) is a cementitious composite which serves complex formworks without mechanical vibrations with superior deformability and high resistance to segregation. Besides, the recycled aggregate concrete (RAC) is also developing rapidly and along with the ever‐increasing sustainable demand for infrastructure. The combination of the fibers, RAC, and SCC may create advantages for the construction industry. In this study, the polypropylene (PP) fiber at 0.1, 0.15, 0.2, and 0.25% volume fractions and steel fibers at 0.25, 0.5, 0.75, and 1% volume fractions are introduced into fiber‐reinforced recycled aggregate self‐compacting concrete (FR‐RASCC). Both fresh property and hardened mechanical performance, comprising compressive and tensile strengths and modulus of elasticity are analyzed. The fibers validate the optimal 0.1% volume fraction for PP fiber and 0.75% volume fraction for steel fiber. In addition, the results are proved to enhance the mechanical properties and reduce cracking despite the negative impact on the fresh property. Moreover, the experimental outcomes are compared with previous researches to establish the linear model, demonstrating the relationship between fiber fraction and the mechanical properties.
Aung, Y, Khabbaz, H & Fatahi, B 2019, 'Mixed hardening hyper-viscoplasticity model for soils incorporating non-linear creep rate – H-creep model', International Journal of Plasticity, vol. 120, pp. 88-114.
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© 2019 Elsevier Ltd. This paper focuses on the deformation of soils considering the time-dependent stress-strain evolution. In this paper, a new mixed hardening hyper-viscoplasticity model is proposed for the derivation of the time-dependent constitutive behaviour of soils, with the intention to capture the variation in the shapes of the yield loci by pursuing non-associated flow rules and accounting for kinematic hardening effects. The distinctive departure from the existing viscoplasticity models is the application of thermodynamics, based upon the use of internal variables, to postulate free-energy and dissipation potential functions, from which the corresponding yield locus, isotropic and kinematic hardening laws, flow rules and the elasticity law are deduced in a systematic procedure. The kinematic hardening behaviour of the yield locus is considered using the shift stress, resulting from the additional plastic component of the free-energy function. A non-linear creep formulation is postulated to address the limitation of over-estimating long-term settlement and incorporated into the model for more reliable predictions. The major parameters required for the model are identified, along with the summary of descriptions on how the model parameters can readily be determined. Non-associated behaviour is found to be a natural consequence of this approach, whenever the division between dissipated and stored plastic work is not equal. This study aims to provide a theoretical background and a numerical implementation for those who are interested in the advancement of constitutive modelling of soil behaviour under the framework of hyperplasticity. Validity and versatility of the proposed constitutive model are evaluated against triaxial and oedometer test results available in literature.
Azar, APK, Askari, G, Crispini, L, Pour, AB, Zoheir, B & Pradhan, B 2019, 'Field and spaceborne imagery data for evaluation of the paleo-stress regime during formation of the Jurassic dike swarms in the Kalateh Alaeddin Mountain area, Shahrood, north Iran', Arabian Journal of Geosciences, vol. 12, no. 17.
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© 2019, Saudi Society for Geosciences. Dike swarms are commonly linked with extensional structures in diverse geodynamic environments. Mafic dyke swarms are typically used to reconstruct the paleo-stress fields of a given region. These dikes are considered paleo-stress indicators and excellent time marker (if related geochronological data are available) of the local and regional stress fields. In the Middle-Late Jurassic, swarms of mafic dikes emplaced into the Neoproterozoic schists and amphibolites in the Kalateh Alaeddin Mountain area in south Shahrood, north Iran. These dikes with different thicknesses show a general east–west strike direction, with mostly a steep dip angle. In this paper, we present structural data of these dike swarms for the sake of assessing the paleo-stress state and the magma pressure ratio at the time of their emplacement. Field and structural data are integrated with ASTER Global Digital Elevation Model (GDEM) and Centre National d’Etudes Spatiales (CNES)/SPOT imagery data, to extract important parameters of the investigated dikes and controlling fault/joint sets. Orientation of the principal paleo-stress axes, quantification of the stress ratio, and the associated magma pressure ratio (driving stress ratio) were calculated using the stereographic projection and Mohr’s circle reconstruction techniques. The results reveal that the maximum paleo-stress component (σ1) was sub-vertical and the intermediate (σ2) and minimum (σ3) paleo-stresses components were sub-horizontal in N264° E and N173° E trends, respectively. Due to the low value of the driving stress ratio (R = 0.05), these dikes developed perpendicular to the minimum principal stress (in E–W direction). The stress ratio value (ø = 0.66) indicates a moderately oblate stress ellipsoid. The orientation of the principal paleo-stress axes and the oblate ellipsoid are indicative of the dike emplacement during a N–S-directed tectonic extension, in agreement with the Jurassic subsidence...
AzariJafari, H, Taheri Amiri, MJ, Ashrafian, A, Rasekh, H, Barforooshi, MJ & Berenjian, J 2019, 'Ternary blended cement: An eco-friendly alternative to improve resistivity of high-performance self-consolidating concrete against elevated temperature', Journal of Cleaner Production, vol. 223, pp. 575-586.
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© 2019 Elsevier Ltd The unique fresh and hardened properties of high-performance self-consolidating concrete (HPSCC) led to an extensive application of this mixture in high-rise buildings. In this paper, the elevated temperature resistivity of 19 HPSCC mixtures incorporating binary and ternary blends of fly ash, silica fume, natural zeolite, and metakaolin was investigated. Changes in mass, compressive strength and ultrasonic pulse velocity (UPV) of the mixtures were measured at different temperatures (20, 300, 500, and 700 °C). A life cycle assessment (LCA) was also employed to explore the environmental performance of the mixtures. The test results revealed that in ambient temperature, ternary mixtures incorporating natural zeolite and fly ash or natural zeolite and metakaolin have lower compressive strength than that of the control mixture. The residual compressive strengths of fly ash-silica fume-incorporated mixture was similar to those in binary mixtures. The UPV test results revealed a larger than 50% reduction in transition velocity when the temperature was above 500 °C, and there is a strong association between the UPV and compressive strength test results of the mixtures at different temperatures, but the correlation decreased inversely proportional to the exposure temperature. Among the ternary mixtures, those mixtures that incorporate natural zeolite indicate the most significant mass loss after exposing to elevated temperature. The environmental results indicate that the substitution of pozzolanic materials with Portland cement may not always be beneficial. The ecosystem quality results of binary fly ash mixtures were larger than the control mixture due to the extensive transportation distance of import. In addition, metakaolin binary mixture exposes larger damage to the resources. Silica fume-incorporated mixtures had significant damage to human health. The ternary blended mixtures can be a remedy to obtain the optimized fire-resistant results and to...
Azeez, O, Pradhan, B, Shafri, H, Shukla, N, Lee, C-W & Rizeei, H 2019, 'Modeling of CO Emissions from Traffic Vehicles Using Artificial Neural Networks', Applied Sciences, vol. 9, no. 2, pp. 313-313.
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Traffic emissions are considered one of the leading causes of environmental impact in megacities and their dangerous effects on human health. This paper presents a hybrid model based on data mining and GIS models designed to predict vehicular Carbon Monoxide (CO) emitted from traffic on the New Klang Valley Expressway, Malaysia. The hybrid model was developed based on the integration of GIS and the optimized Artificial Neural Network algorithm that combined with the Correlation based Feature Selection (CFS) algorithm to predict the daily vehicular CO emissions and generate prediction maps at a microscale level in a small urban area by using a field survey and open source data, which are the main contributions to this paper. The other contribution is related to the case study, which represents the spatial and quantitative variations in the vehicular CO emissions between toll plaza areas and road networks. The proposed hybrid model consists of three steps: the first step is the implementation of the correlation-based Feature Selection model to select the best model’s predictors; the second step is the prediction of vehicular CO by using a multilayer perceptron neural network model; and the third step is the creation of micro scale prediction maps. The model was developed using six traffic CO predictors: number of vehicles, number of heavy vehicles, number of motorbikes, temperature, wind speed and a digital surface model. The network architecture and its hyperparameters were optimized through a grid search approach. The traffic CO concentrations were observed at 15-min intervals on weekends and weekdays, four times per day. The results showed that the developed model had achieved validation accuracy of 80.6 %. Overall, the developed models are found to be promising tools for vehicular CO simulations in highly congested areas.
Azeez, OS, Pradhan, B, Jena, R, Jung, HS & Ahmed, AA 2019, 'Traffic Emission Modelling Using LiDAR Derived Parameters and Integrated Geospatial Model', Korean Journal of Remote Sensing, vol. 35, no. 1, pp. 137-149.
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Traffic emissions are the main cause of environmental pollution in cities and respiratory problems amongst people. This study developed a model based on an integration of support vector regression (SVR) algorithm and geographic information system (GIS) to map traffic carbon monoxide (CO) concentrations and produce prediction maps from micro level to macro level at a particular time gap in a day in a very densely populated area (Utara–Selatan Expressway–NKVE, Kuala Lumpur, Malaysia). The proposed model comprised two models: the first model was implemented to estimate traffic CO concentrations using the SVR model, and the second model was applied to create prediction maps at different times a day using the GIS approach. The parameters for analysis were collected from field survey and remote sensing data sources such as very-high-resolution aerial photos and light detection and ranging point clouds. The correlation coefficient was 0.97, the mean absolute error was 1.401 ppm and the root mean square error was 2.45 ppm. The proposed models can be effectively implemented as decision-making tools to find a suitable solution for mitigating traffic jams near tollgates, highways and road networks.
Bao, T, Damtie, MM, Yu, ZM, Liu, Y, Jin, J, Wu, K, Deng, CX, Wei, W, Wei, XL & Ni, B-J 2019, 'Green Synthesis of Fe3O4@Carbon Filter Media for Simultaneous Phosphate Recovery and Nitrogen Removal from Domestic Wastewater in Biological Aerated Filters', ACS Sustainable Chemistry & Engineering, vol. 7, no. 19, pp. 16698-16709.
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Copyright © 2019 American Chemical Society. Domestic wastewater depth processing and reclamation are essential in the alleviation of global water shortage. In this study, an innovative filter media (i.e., Fe3O4@Carbon filter media [FCM]) was synthesized and subsequently used in a biological aerated filter (BAF) for simultaneous phosphate recovery and nitrogen removal (SPN) from domestic wastewater. The performance of FCM was compared with the commercially available ceramsite (CAC). The results showed that the performance of FCMBAF was better than that of CACBAF; as far as SPN is concerned, the magnetic field of FCMBAF could accelerate the growth rate of biofilm. Moreover, the nitrospira and nirK gene copy numbers of FCMBAF were considerably higher than those of CACBAF. Interestingly, the interconnectivity and uniformity of pores were also suitable for the microdistribution of biofilm, where different aerobic and anaerobic zones of the FCM were formed. This facilitates the microinteraction between the key microorganisms and the filter media that successfully enhanced the nitrogen removal. The phosphate recovery was attained via hydroxyapatite (Ca10(PO4)6(OH)2) formation, which resulted from the reaction between phosphate (PO43-) and FCM. The average effluent concentrations of total organic carbon (TOC), total nitrogen (TN), ammonia nitrogen (NH4+-N), and PO43- were 8.12, 6.18, 0.997, and 0.073 mg/L of FCMBAF, respectively, which were lower than those from the national standard (CODcr ≤ 50 mg L-1, NH4+-N ≤ 5.0 mg L-1, TN ≤ 15 mg L-1, TP ≤ 0.5 mg L-1, GB 18918-2002, first standard). Thus, FCM demonstrated a promising potential for SPN and wastewater recycling of BAF in domestic wastewater treatment.
Baral, P, Rujikiatkamjorn, C, Indraratna, B, Leroueil, S & Yin, J-H 2019, 'Radial Consolidation Analysis Using Delayed Consolidation Approach', Journal of Geotechnical and Geoenvironmental Engineering, vol. 145, no. 10, pp. 04019063-04019063.
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© 2019 American Society of Civil Engineers. The paper offers an analytical solution for radial consolidation that captures isotaches with a strain-rate dependency of preconsolidation pressure. These relationships are obtained based on constant-rate-of-strain (CRS) and long-term consolidation (LTC) tests and then used in the radial consolidation model incorporating the field strain rate, which is generally much lower compared with the typical laboratory environment. In this study, the calculated settlement and associated excess pore-water pressure are obtained using the equivalent preconsolidation pressure from the reference isotache within the (σp′/σp0′)-(ϵv) domain. Moreover, the change in Cα/Cc ratio (i.e., secondary compression index/compression index) with decreasing strain rate is used to calculate the long-term settlement. This method is then validated using various case histories in Australia and Southeast Asia, where excess pore-water pressure is dissipated at a slower rate in relation to the observed settlement.
Barambu, NU, Bilad, MR, Wibisono, Y, Jaafar, J, Mahlia, TMI & Khan, AL 2019, 'Membrane Surface Patterning as a Fouling Mitigation Strategy in Liquid Filtration: A Review', Polymers, vol. 11, no. 10, pp. 1687-1687.
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Membrane fouling is seen as the main culprit that hinders the widespread of membrane application in liquid-based filtration. Therefore, fouling management is key for the successful implementation of membrane processes, and it is done across all magnitudes. For optimum operation, membrane developments and surface modifications have largely been reported, including membrane surface patterning. Membrane surface patterning involves structural modification of the membrane surface to induce secondary flow due to eddies, which mitigate foulant agglomeration and increase the effective surface area for improved permeance and antifouling properties. This paper reviews surface patterning approaches used for fouling mitigation in water and wastewater treatments. The focus is given on the pattern formation methods and their effect on overall process performances.
Barua, P & Rahman, SH 2019, 'Sustainable Livelihood of Vulnerable Communities in Southern Coast of Bangladesh through the Utilization of Mangroves', Asian Journal of Water, Environment and Pollution, vol. 16, no. 1, pp. 59-67.
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Barua, P, Meah, MM & Rahman, SH 2019, 'Abundance of Macrobenthos with Special Reference to Some Physico-Chemical Parameters of South-Eastern Coastal Area, Bangladesh', Asian Journal of Water, Environment and Pollution, vol. 16, no. 4, pp. 51-60.
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Beiranvand Pour, A, Park, Y, Crispini, L, Läufer, A, Kuk Hong, J, Park, T-YS, Zoheir, B, Pradhan, B, Muslim, AM, Hossain, MS & Rahmani, O 2019, 'Mapping Listvenite Occurrences in the Damage Zones of Northern Victoria Land, Antarctica Using ASTER Satellite Remote Sensing Data', Remote Sensing, vol. 11, no. 12, pp. 1408-1408.
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Listvenites normally form during hydrothermal/metasomatic alteration of mafic and ultramafic rocks and represent a key indicator for the occurrence of ore mineralizations in orogenic systems. Hydrothermal/metasomatic alteration mineral assemblages are one of the significant indicators for ore mineralizations in the damage zones of major tectonic boundaries, which can be detected using multispectral satellite remote sensing data. In this research, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) multispectral remote sensing data were used to detect listvenite occurrences and alteration mineral assemblages in the poorly exposed damage zones of the boundaries between the Wilson, Bowers and Robertson Bay terranes in Northern Victoria Land (NVL), Antarctica. Spectral information for detecting alteration mineral assemblages and listvenites were extracted at pixel and sub-pixel levels using the Principal Component Analysis (PCA)/Independent Component Analysis (ICA) fusion technique, Linear Spectral Unmixing (LSU) and Constrained Energy Minimization (CEM) algorithms. Mineralogical assemblages containing Fe2+, Fe3+, Fe-OH, Al-OH, Mg-OH and CO3 spectral absorption features were detected in the damage zones of the study area by implementing PCA/ICA fusion to visible and near infrared (VNIR) and shortwave infrared (SWIR) bands of ASTER. Silicate lithological groups were mapped and discriminated using PCA/ICA fusion to thermal infrared (TIR) bands of ASTER. Fraction images of prospective alteration minerals, including goethite, hematite, jarosite, biotite, kaolinite, muscovite, antigorite, serpentine, talc, actinolite, chlorite, epidote, calcite, dolomite and siderite and possible zones encompassing listvenite occurrences were produced using LSU and CEM algorithms to ASTER VNIR+SWIR spectral bands. Several potential zones for listvenite occurrences were identified, typically in association with mafic metavolcanic rocks (Glasgow Volcanic...
Biradar, J, Banerjee, S, Shankar, R, Ghosh, P, Mukherjee, S & Fatahi, B 2019, 'Response of square anchor plates embedded in reinforced soft clay subjected to cyclic loading', Geomechanics and Engineering, vol. 17, no. 2, pp. 165-173.
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Plate anchors are generally used for structures like transmission towers, mooring systems etc. where the uplift and lateral forces are expected to be predominant. The capacity of anchor plate can be increased by the use of geosynthetics without altering the size of plates. Numerical simulations have been carried out on three different sizes of square anchor plates. A single layer geosynthetic has been used as reinforcement in the analysis and placed at three different positions from the plate. The effects of various parameters like embedment ratio, position of reinforcement, width of reinforcement, frequency and loading amplitude on the pull out capacity have been presented in this study. The load-displacement behaviour of anchors for various embedment ratios with and without reinforcement has been also observed. The pull out load, corresponding to a displacement equal to each of the considered maximum amplitudes of a given frequency, has been expressed in terms of a dimensionless breakout factor. The pull out load for all anchors has been found to increase by more than 100% with embedment ratio varying from 1 to 6. Finally a semi empirical formulation for breakout factor for square anchors in reinforced soil has also been proposed by carrying out regression analysis on the data obtained from numerical simulations.
Bui, HH, Ha, NH, Nguyen, TND, Nguyen, AT, Pham, TTH, Kandasamy, J & Nguyen, TV 2019, 'Integration of SWAT and QUAL2K for water quality modeling in a data scarce basin of Cau River basin in Vietnam', Ecohydrology & Hydrobiology, vol. 19, no. 2, pp. 210-223.
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© 2019 European Regional Centre for Ecohydrology of the Polish Academy of Sciences Water quality modeling in a river basin often faces the problem of having a large number of parameters yet limited available data. The important inputs to the water quality model are pollution concentrations and discharge from river tributaries, lateral inflows and related pollution load from different sources along the river. In general, such an extensive data set is rarely available, especially for data scarce basins. This makes water quality modeling more challenging. However, integration of models may be able to fill this data gap. Selection of models should be made based on the data that is available for the river basin. For the case of Cau River basin, the SWAT and QUAL2K models were selected. The outputs of SWAT model for lateral inflows and discharges of ungauged tributaries, and the observed pollutant concentrations data and estimated pollution loads of sub-watersheds were used as inputs to the water quality model QUAL2K. The resulting QUAL2K model was calibrated and validated using recent water quality data for two periods in 2014. Four model performance ratings PBIAS, NSE, RSR and R2 were used to evaluate the model results. PBIAS index was chosen for water quality model evaluation because it more adequately accounted for the large uncertainty inherent in water quality data. In term of PBIAS, the calibration and validation results for Cau River water quality model were in the “very good” performance range with ǀPBIASǀ < 15%. The obtained results could be used to support water quality management and control in the Cau River basin.
Bui, Moayedi, Kalantar, Osouli, Gör, Pradhan, Nguyen & Rashid 2019, 'Harris Hawks Optimization: A Novel Swarm Intelligence Technique for Spatial Assessment of Landslide Susceptibility', Sensors, vol. 19, no. 16, pp. 3590-3590.
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In this research, the novel metaheuristic algorithm Harris hawks optimization (HHO) is applied to landslide susceptibility analysis in Western Iran. To this end, the HHO is synthesized with an artificial neural network (ANN) to optimize its performance. A spatial database comprising 208 historical landslides, as well as 14 landslide conditioning factors—elevation, slope aspect, plan curvature, profile curvature, soil type, lithology, distance to the river, distance to the road, distance to the fault, land cover, slope degree, stream power index (SPI), topographic wetness index (TWI), and rainfall—is prepared to develop the ANN and HHO–ANN predictive tools. Mean square error and mean absolute error criteria are defined to measure the performance error of the models, and area under the receiving operating characteristic curve (AUROC) is used to evaluate the accuracy of the generated susceptibility maps. The findings showed that the HHO algorithm effectively improved the performance of ANN in both recognizing (AUROCANN = 0.731 and AUROCHHO–ANN = 0.777) and predicting (AUROCANN = 0.720 and AUROCHHO–ANN = 0.773) the landslide pattern.
Castel, A, François, R, Santisi d’Avila, MP & Jenkins, D 2019, 'New service limit state criteria for reinforced concrete in chloride environments', Corrosion Reviews, vol. 37, no. 1, pp. 21-29.
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Abstract In chloride environments, reinforcement stress limits, intended to control flexural cracking, are one of the most important requirements for service limit state (SLS) design. However, concrete damage at the steel-concrete interface between bending cracks, so called cover-controlled cracking, is always correlated to areas of severe steel reinforcement corrosion. Based on the assumption that cover-controlled cracking should be limited, a model has been developed to provide alternative reinforcement stress limits in marine exposure conditions such as concrete in sea water, including permanently submerged, spray zone and tidal/splash zone, as well as coastal constructions located within 1 km of the shoreline. In this paper, the new reinforcement stress limitation is compared to the Australian Standards AS3600 concrete building code and AS5100.5 concrete bridge code provisions. Analysis shows that the new model is very sensitive to the reinforcement percentage of the cross-section. As a result, the existing AS3600 and AS5100.5 code provisions are more conservative than the new limitation for lightly to normally reinforced concrete cross-section. In this case, crack width control governs the SLS design. However, for normally to heavily reinforced concrete cross-section, the new model provides more conservative results suggesting that cover-controlled cracking governs the SLS design.
Castillo, EHC, Thomas, N, Al-Ketan, O, Rowshan, R, Abu Al-Rub, RK, Nghiem, LD, Vigneswaran, S, Arafat, HA & Naidu, G 2019, '3D printed spacers for organic fouling mitigation in membrane distillation', Journal of Membrane Science, vol. 581, pp. 331-343.
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Chan, QN, Fattah, IMR, Zhai, G, Yip, HL, Chen, TBY, Yuen, ACY, Yang, W, Wehrfritz, A, Dong, X, Kook, S & Yeoh, GH 2019, 'Color-ratio pyrometry methods for flame–wall impingement study', Journal of the Energy Institute, vol. 92, no. 6, pp. 1968-1976.
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© 2018 Energy Institute The use of color-ratio pyrometry (CRP) methods, with variable or prescribed soot content (KL) to image flame–wall interactions was examined, with results compared with that obtained using the more mature two-color pyrometry (TCP) technique. The CRP and TCP methods were applied to flame–wall impingement images recorded in a optically-accessible constant volume combustion chamber (CVCC) under compression-ignition (CI) engine conditions. Good correlation in the result trends were observed for the CRP method with fixed KL output and that generated using TCP. Slight discrepancies in the predicted absolute temperature values were observed, which were linked to the difference in the KL value prescribed to the CRP method, and the KL value predicted using TCP. No useful output was obtained with CRP method with variable soot output because of channel noise. A simplified flame transparency modeling was performed to assess the inherent errors associated with the pyrometry methods. The results indicated that the uncertainties arising from the fixing of the KL output appeared acceptable.
Cheah, R, Billa, L, Chan, A, Teo, FY, Pradhan, B & Alamri, AM 2019, 'Geospatial Modelling of Watershed Peak Flood Discharge in Selangor, Malaysia', Water, vol. 11, no. 12, pp. 2490-2490.
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Conservative peak flood discharge estimation methods such as the rational method do not take into account the soil infiltration of the precipitation, thus leading to inaccurate estimations of peak discharges during storm events. The accuracy of estimated peak flood discharge is crucial in designing a drainage system that has the capacity to channel runoffs during a storm event, especially cloudbursts and in the analysis of flood prevention and mitigation. The aim of this study was to model the peak flood discharges of each sub-watershed in Selangor using a geographic information system (GIS). The geospatial modelling integrated the watershed terrain model, the developed Soil Conservation Service Curve Cumber (SCS-CN) and precipitation to develop an equation for estimation of peak flood discharge. Hydrological Engineering Center-Hydrological Modeling System (HEC-HMS) was used again to simulate the rainfall-runoff based on the Clark-unit hydrograph to validate the modelled estimation of peak flood discharge. The estimated peak flood discharge showed a coefficient of determination, r2 of 0.9445, when compared with the runoff simulation of the Clark-unit hydrograph. Both the results of the geospatial modelling and the developed equation suggest that the peak flood discharge of a sub-watershed during a storm event has a positive relationship with the watershed area, precipitation and Curve Number (CN), which takes into account the soil bulk density and land-use of the studied area, Selangor in Malaysia. The findings of the study present a comparable and holistic approach to the estimation of peak flood discharge in a watershed which can be in the absence of a hydrodynamic simulation model.
Chen, C, Guo, W & Ngo, HH 2019, 'Pesticides in stormwater runoff—A mini review', Frontiers of Environmental Science & Engineering, vol. 13, no. 5.
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© 2019, Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature. Recently, scientific interest has grown in harvesting and treating stormwater for potable water use, in order to combat the serious global water scarcity issue. In this context, pesticides have been identified as the key knowledge gap as far as reusing stormwater is concerned. This paper reviewed the presence of pesticides in stormwater runoff in both rural and urban areas. Specifically, the sources of pesticide contamination and possible pathways were investigated in this review. Influential factors affecting pesticides in stormwater runoff were critically identified as: 1) characteristics of precipitation, 2) properties of pesticide, 3) patterns of pesticides use, and 4) properties of application surface. The available pesticide mitigation strategies including best management practice (BMP), low impact development (LID), green infrastructure (GI) and sponge city (SC) were also included in this paper. In the future, large-scale multi-catchment studies that directly evaluate pesticide concentrations in both urban and rural stormwater runoff will be of great importance for the development of effective pesticides treatment approaches and stormwater harvesting strategies.[Figure not available: see fulltext.].
Chen, F, Lu, S, Hu, X, He, Q, Feng, C, Xu, Q, Chen, N, Ngo, HH & Guo, H 2019, 'Multi-dimensional habitat vegetation restoration mode for lake riparian zone, Taihu, China', Ecological Engineering, vol. 134, pp. 56-64.
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© 2019 Elsevier B.V. The riparian zones that were surround bodies of fresh water have been extensively degraded by human influence. Their restoration strength and management are an issue of urgent. Particularly, the knowledge based for the restoration of riparian zone has expanded in recent years. However, progress on a global scale has been limited, because little is known about its complex and diverse functions and structures. A national ecological restoration project of Taihu Lake (China)provided a case study for classifying and restoring the riparian zone. In this work, we quantified the classification of riparian zone, vegetation-zone in the ecotones and a recommended suite of introduced riparian vegetation communities. Taking the structures of the ecotones, soil conditions, vegetation configurations, and anthropogenic disturbances into account, six types of vegetation-zone were used to classify riparian zone, which are as follow: reefs, islands, dokdo–island, island–shore, dike–shore, and shoreland. Then a multi-dimensional habitat vegetation restoration mode for each type based on six vegetation-zones were also recommended. The water ecological quality was developed to a healthy state under this implement. Therefore, results suggest that profound division of habitat-vegetation is important in the modern ecological engineering theories for riparian zone. In order to provide a key parameter for Taihu Lake and other worldwide lakes with similar characteristics, an eco-restoration model and a reconstruction scheme for the vegetation community have been presented. In a conclusion, these recommendations could largely assist further development for lake management.
Chen, H, Li, A, Cui, C, Ma, F, Cui, D, Zhao, H, Wang, Q, Ni, B & Yang, J 2019, 'AHL-mediated quorum sensing regulates the variations of microbial community and sludge properties of aerobic granular sludge under low organic loading', Environment International, vol. 130, pp. 104946-104946.
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© 2019 The Authors Aerobic granular sludge (AGS) is promising in wastewater treatment. However, the formation and existence of AGS under low organic loading rate (OLR) is still not fully understood due to a knowledge gap in the variations and correlations of N-acyl-homoserine lactones (AHLs), the microbial community, extracellular polymeric substances (EPS) and other physiochemical granule properties. This study comprehensively investigated the AHL-mediated quorum sensing (QS) and microbial community characters in the AGS fed with ammonium-rich wastewater under a low OLR of 0.15 kg COD (m3 d)−1. The results showed that the AGS appeared within 90 days, and the size of mature granules was over 700 μm with strong settleability and ammonium removal performance. More tightly-bound extracellular polysaccharide and tightly-bound extracelluar protein were produced in the larger AGS. C10-HSL and C12-HSL gradually became dominant in sludge, and short-chain AHLs dominated in water. EPS producers and autotrophic nitrifiers were successfully retained in the AGS under low OLR. AHL-mediated QS utilized C10-HSL, C12-HSL and 3OC6-HSL as the critical AHLs to regulate the TB-EPS in aerobic granulation, and autotrophic nitrifiers may perform interspecific communication with C10-HSL. The correlations of bacterial genera with AGS properties and AHLs were complex due to the dynamic fluctuations of microbial composition and other variable factors in the mixed-culture system. These findings confirmed the participation of AHL-mediated QS in the regulation of microbial community characters and AGS properties under low OLR, which may provide guidance for the operation of AGS systems under low OLR from a microbiological viewpoint.
Chen, W, Pradhan, B, Li, S, Shahabi, H, Rizeei, HM, Hou, E & Wang, S 2019, 'Novel Hybrid Integration Approach of Bagging-Based Fisher’s Linear Discriminant Function for Groundwater Potential Analysis', Natural Resources Research, vol. 28, no. 4, pp. 1239-1258.
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© 2019, International Association for Mathematical Geosciences. Groundwater is a vital water source in the rural and urban areas of developing and developed nations. In this study, a novel hybrid integration approach of Fisher’s linear discriminant function (FLDA) with rotation forest (RFLDA) and bagging (BFLDA) ensembles was used for groundwater potential assessment at the Ningtiaota area in Shaanxi, China. A spatial database with 66 groundwater spring locations and 14 groundwater spring contributing factors was prepared; these factors were elevation, aspect, slope, plan and profile curvatures, sediment transport index, stream power index, topographic wetness index, distance to roads and streams, land use, lithology, soil and normalized difference vegetation index. The classifier attribute evaluation method based on the FLDA model was implemented to test the predictive competence of the mentioned contributing factors. The area under curve, confidence interval at 95%, standard error, Friedman test and Wilcoxon signed-rank test were used to compare and validate the success and prediction competence of the three applied models. According to the achieved results, the BFLDA model showed the most prediction competence, followed by the RFLDA and FLDA models, respectively. The resulting groundwater spring potential maps can be used for groundwater development plans and land use planning.
Chen, W, Yan, X, Zhao, Z, Hong, H, Bui, DT & Pradhan, B 2019, 'Spatial prediction of landslide susceptibility using data mining-based kernel logistic regression, naive Bayes and RBFNetwork models for the Long County area (China)', Bulletin of Engineering Geology and the Environment, vol. 78, no. 1, pp. 247-266.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The main goal of this study is to assess and compare three advanced machine learning techniques, namely, kernel logistic regression (KLR), naïve Bayes (NB), and radial basis function network (RBFNetwork) models for landslide susceptibility modeling in Long County, China. First, a total of 171 landslide locations were identified within the study area using historical reports, aerial photographs, and extensive field surveys. All the landslides were randomly separated into two parts with a ratio of 70/30 for training and validation purposes. Second, 12 landslide conditioning factors were prepared for landslide susceptibility modeling, including slope aspect, slope angle, plan curvature, profile curvature, elevation, distance to faults, distance to rivers, distance to roads, lithology, NDVI (normalized difference vegetation index), land use, and rainfall. Third, the correlations between the conditioning factors and the occurrence of landslides were analyzed using normalized frequency ratios. A multicollinearity analysis of the landslide conditioning factors was carried out using tolerances and variance inflation factor (VIF) methods. Feature selection was performed using the chi-squared statistic with a 10-fold cross-validation technique to assess the predictive capabilities of the landslide conditioning factors. Then, the landslide conditioning factors with null predictive ability were excluded in order to optimize the landslide models. Finally, the trained KLR, NB, and RBFNetwork models were used to construct landslide susceptibility maps. The receiver operating characteristics (ROC) curve, the area under the curve (AUC), and several statistical measures, such as accuracy (ACC), F-measure, mean absolute error (MAE), and root mean squared error (RMSE), were used for the assessment, validation, and comparison of the resulting models in order to choose the best model in this study. The validation...
Chen, W, Zhang, Y, Wang, D & Wu, C 2019, 'Investigation on damage development of AP1000 nuclear power plant in strong ground motions with numerical simulation', Nuclear Engineering and Technology, vol. 51, no. 6, pp. 1669-1680.
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© 2019 Seismic safety is considered to be one of the key design objectives of AP1000 nuclear power plant (NPP) in strong earthquakes. Dynamic behavior, damage development and aggravation effect are studied in this study for the three main components of AP1000 NPP, namely reinforced concrete shield building (RCSB), steel vessel containment (SVC) and reinforced concrete auxiliary building (RCAB). Characteristics including nonlinear concrete tension and compressive constitutions with plastic damage are employed to establish the numerical model, which is further validated by existing studies. The author investigates three earthquakes and eight input levels with the maximum magnitude of 2.4 g and the results show that the concrete material of both RCSB and RCAB have suffered serious damage in intense earthquakes. Considering RCAB in the whole NPP, significant damage aggravation effect can be detected, which is mainly concentrated at the upper intersection between RCSB and RCAB. SVC and reinforcing bar demonstrate excellent seismic performance with no obvious damage.
Chen, W-H, Cheng, C-L, Show, P-L & Ong, HC 2019, 'Torrefaction performance prediction approached by torrefaction severity factor', Fuel, vol. 251, pp. 126-135.
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Chen, W-H, Lee, K & Ong, H 2019, 'Biofuel and Bioenergy Technology', Energies, vol. 12, no. 2, pp. 290-290.
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Biomass is considered as a renewable resource because of its short life cycle, and biomass-derived biofuels are potential substitutes to fossil fuels [...]
Chen, W-H, Lin, Y-Y, Liu, H-C, Chen, T-C, Hung, C-H, Chen, C-H & Ong, HC 2019, 'A comprehensive analysis of food waste derived liquefaction bio-oil properties for industrial application', Applied Energy, vol. 237, pp. 283-291.
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© 2019 Elsevier Ltd Hydrothermal liquefaction is a promising technology to convert wet biomass into bio-oil with high calorific value and without drying process. To evaluate the potential application of liquefaction bio-oil in industry, the present study aims to provide a comprehensive analysis on the properties of liquefaction bio-oil derived from food waste. The food waste is pretreated with K2CO3 at 100 °C for 1 h, followed by liquefaction in a semi-pilot reactor at 320 °C for 30 min. The higher heating value of produced bio-oil is 34.79 MJ kg−1, accounting for 53% increase when compared to the feedstock (22.74 MJ kg−1). The ignition and burnout temperatures of the bio-oil are lower than other liquefaction bio-oils, reflecting its higher reactivity and combustibility. Meanwhile, the bio-oil has a higher oxidation onset temperature than pyrolysis bio-oils, showing its higher thermal stability. The independent parallel reaction model in association with the particle swarm optimization indicates that the pyrolysis kinetics of the bio-oil can be approximated by four groups. The component analysis further reveals two important groups of fatty acids and amides in the bio-oil, stemming from the conversion of carbohydrate and protein in the food waste. The comprehensive analysis shows that the liquefaction bio-oil from food waste, characterized by higher energy density and better combustibility, is a potential substitute to the fossil fuels.
Chen, W-H, Wang, C-W, Ong, HC, Show, PL & Hsieh, T-H 2019, 'Torrefaction, pyrolysis and two-stage thermodegradation of hemicellulose, cellulose and lignin', Fuel, vol. 258, pp. 116168-116168.
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Chen, X, Lai, C-Y, Fang, F, Zhao, H-P, Dai, X & Ni, B-J 2019, 'Model-based evaluation of selenate and nitrate reduction in hydrogen-based membrane biofilm reactor', Chemical Engineering Science, vol. 195, pp. 262-270.
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© 2018 Elsevier Ltd A biofilm model was developed to describe the simultaneous NO3− and SeO42− reduction in a H2-based membrane biofilm reactor (MBfR). Model calibration and validation was conducted using the experimental data of a reported H2-based MBfR. With a good level of identifiability, the SeO42− affinity constant and the SeO32− affinity constant were estimated at 9.80 ± 0.51 g Se m−3 and 1.83 ± 0.38 g Se m−3, respectively. The model was then applied to evaluate the effects of key operating conditions on the single-stage H2-based MBfR and the role of reactor configuration through comparing two-stage to single-stage MBfR systems. The results showed that (i) high SeO42− or low NO3− concentration in the influent favored the growth of selenate-reducing bacteria (SeRB) and therefore benefited the Se removal, (ii) the influent dissolved oxygen slightly inhibited the Se removal through enhancing the aerobic microbial respiration on H2, (iii) the H2 supply should be controlled at a proper level to avoid SeRB suppression and H2 wastage, (iv) thin biofilm should be avoided to ensure a protected niche for SeRB and therefore a promising Se removal, and (v) the two-stage MBfR configuration offered relatively higher efficiency in removing Se and NO3− simultaneously under the same loading condition.
Chen, X, Ni, B & Sin, G 2019, 'Nitrous oxide production in autotrophic nitrogen removal granular sludge: A modeling study', Biotechnology and Bioengineering, vol. 116, no. 6, pp. 1280-1291.
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AbstractThe sustainability of autotrophic granular system performing partial nitritation and anaerobic ammonium oxidation (anammox) for complete nitrogen removal is impaired by the production of nitrous oxide (N2O). A systematic analysis of the pathways and affecting parameters is, therefore, required for developing N2O mitigation strategies. To this end, a mathematical model capable of describing different N2O production pathways was defined in this study by synthesizing relevant mechanisms of ammonium‐oxidizing bacteria (AOB), nitrite‐oxidizing bacteria, heterotrophic bacteria (HB), and anammox bacteria. With the model validity reliably tested and verified using two independent sets of experimental data from two different autotrophic nitrogen removal biofilm/granular systems, the defined model was applied to reveal the underlying mechanisms of N2O production in the granular structure as well as the impacts of operating conditions on N2O production. The results show that: (a) in the aerobic zone close to the granule surface where AOB contribute to N2O production through both the AOB denitrification pathway and the NH2OH pathway, the co‐occurring HB consume N2O produced by AOB but indirectly enhance the N2O production by providing NO from NO2− reduction for the NH2OH pathway, (b) the inner anoxic zone of granules with the dominance of anammox bacteria acts as a sink for NO2− diffusing from the outer aerobic zone and, therefore, reduces N2O production from the AOB denitrification pathway, (c) operating parameters including bulk DO, influent NH4+, and granu...
Chen, X, Sin, G & Ni, B-J 2019, 'Impact of granule size distribution on nitrous oxide production in autotrophic nitrogen removal granular reactor', Science of The Total Environment, vol. 689, pp. 700-708.
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© 2019 Elsevier B.V. This work applied an approach with reactor compartmentation and artificial diffusion to study the impact of granule size distribution on the autotrophic granular reactor performing partial nitritation and anaerobic ammonium oxidation with focus on the nitrous oxide (N2O) production. The results show that the microbial community and the associated N2O production rates in the granular structure are significantly influenced by the granule size distribution. Heterotrophic bacteria growing on microbial decay products tend to be retained and contribute to N2O consumption in relatively small granules. Ammonium-oxidizing bacteria are mainly responsible for N2O production via two pathways in granules of different sizes. Under the conditions studied, such heterogeneity in the granular structure disappears when the number of granule size classes considered reaches >4, where heterotrophic bacteria are completely outcompeted in the granules. In general, larger granules account for a higher portion of the net N2O production, while the trend regarding the volumetric contribution of each granule size class changes with a varied number of granule size classes, due to the different contributions of relevant N2O production pathways (with the heterotrophic denitrification pathway being the most decisive). Overall, with the increasing extent of granule size distribution, the nitrogen removal efficiency decreases slightly but consistently, whereas the N2O production factor increases until the number of granule size classes reaches 4 or above. Practical implications of this work include: i) granules should be controlled as well-distributed as possible in order to obtain high nitrogen removal while minimizing N2O production; ii) granule size distribution should be considered carefully and specifically when modelling N2O production/emission from the autotrophic nitrogen removal granular reactor.
Chen, X, Yang, L, Sun, J, Dai, X & Ni, B-J 2019, 'Modelling of simultaneous nitrogen and thiocyanate removal through coupling thiocyanate-based denitrification with anaerobic ammonium oxidation', Environmental Pollution, vol. 253, pp. 974-980.
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© 2019 Elsevier Ltd Thiocyanate (SCN−)-based autotrophic denitrification (AD) has recently been demonstrated as a promising technology that could be integrated with anaerobic ammonium oxidation (Anammox) to achieve simultaneous removal of nitrogen and SCN−. However, there is still a lack of a complete SCN−-based AD model, and the potential microbial competition/synergy between AD bacteria and Anammox bacteria under different operating conditions remains unknown, which significantly hinders the possible application of coupling SCN−-based AD with Anammox. To this end, a complete SCN−-based AD model was firstly developed and reliably calibrated/validated using experimental datasets. The obtained SCN−-based AD model was then integrated with the well-established Anammox model and satisfactorily verified with experimental data from a system coupling AD with Anammox. The integrated model was lastly applied to investigate the impacts of influent NH4+-N/NO2−-N ratio and SCN− concentration on the steady-state microbial composition as well as the removal of nitrogen and SCN−. The results showed that the NH4+-N/NO2−-N ratio in the presence of a certain SCN− level should be controlled at a proper value so that the maximum synergy between AD bacteria and Anammox bacteria could be achieved while their competition for NO2− would be minimized. For the simultaneous maximum removal (>95%) of nitrogen and SCN−, there existed a negative relationship between the influent SCN− concentration and the optimal NH4+-N/NO2−-N ratio needed. High-level (>95%) simultaneous removal of nitrogen and thiocyanate could be achieved through combining thiocyanate-based autotrophic denitrification and Anammox.
Chen, Y, Alanezi, AA, Zhou, J, Altaee, A & Shaheed, MH 2019, 'Optimization of module pressure retarded osmosis membrane for maximum energy extraction', Journal of Water Process Engineering, vol. 32, pp. 100935-100935.
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© 2019 Elsevier Ltd A full-scale Pressure Retarded Osmosis process (PRO) is optimized in non-ideal operating conditions using Grey Wolf Optimization (GWO) algorithms. Optimization process included the classical parameters that previous studies recommended such as operating pressure, and feed and draw fractions in the mixture solution. The study has revealed that the recommended operating pressure ΔP=Δπ/2 and the ratio of feed or draw solution to the total mixture solution, ̴ 0.5, in a laboratory scale unit or in an ideal PRO process are not valid in a non-ideal full-scale PRO module. The optimization suggested that the optimum operating pressure is less than the previously recommended value of ΔP=Δπ/2. The optimization of hydraulic pressure resulted in 4.4% increase of the energy output in the PRO process. Conversely, optimization of feed fraction in the mixture has resulted in 28%–70% higher energy yield in a single-module PRO process and 9%–54% higher energy yield in a four-modules PRO process. The net energy generated in the optimized PRO process is higher than that in the unoptimized (normal) PRO process. The findings of this study reveal the significance of incorporating machine-learning algorithms in the optimization of PRO process and identifying the preferable operating conditions.
Chen, Z, Duan, X, Wei, W, Wang, S & Ni, B-J 2019, 'Recent advances in transition metal-based electrocatalysts for alkaline hydrogen evolution', Journal of Materials Chemistry A, vol. 7, no. 25, pp. 14971-15005.
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Transition metal-based electrocatalysts for alkaline hydrogen evolution reaction.
Chen, Z, Liu, Y, Wei, W & Ni, B-J 2019, 'Recent advances in electrocatalysts for halogenated organic pollutant degradation', Environmental Science: Nano, vol. 6, no. 8, pp. 2332-2366.
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Advanced electrocatalysts for halogenated organic pollutant degradation.
Chenari, RJ, Fatahi, B, Ghoreishi, M & Taleb, A 2019, 'Physical and numerical modelling of the inherent variability of shear strength in soil mechanics', Geomechanics and Engineering, vol. 17, no. 1, pp. 31-45.
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In this study the spatial variability of soils is substantiated physically and numerically by using random field theory. Heterogeneous samples are fabricated by combining nine homogeneous soil clusters that are assumed to be elements of an adopted random field. Homogeneous soils are prepared by mixing different percentages of kaolin and bentonite at water contents equivalent to their respective liquid limits. Comprehensive characteristic laboratory tests were carried out before embarking on direct shear experiments to deduce the basic correlations and properties of nine homogeneous soil clusters that serve to reconstitute the heterogeneous samples. The tests consist of Atterberg limits, and Oedometric and unconfined compression tests. The undrained shear strength of nine soil clusters were measured by the unconfined compression test data, and then correlations were made between the water content and the strength and stiffness of soil samples with different consistency limits. The direct shear strength of heterogeneous samples of different stochastic properties was then evaluated by physical and numerical modelling using FISH code programming in finite difference software of FLAC 3D . The results of the experimental and stochastic numerical analyses were then compared. The deviation of numerical simulations from direct shear load-displacement profiles taken from different sources were discussed, potential sources of error was introduced and elaborated. This study was primarily to explain the mathematical and physical procedures of sample preparation in stochastic soil mechanics. It can be extended to different problems and applications in geotechnical engineering discipline to take in to account the variability of strength and deformation parameters.
Cheng, DL, Ngo, HH, Guo, WS, Chang, SW, Nguyen, DD & Kumar, SM 2019, 'Microalgae biomass from swine wastewater and its conversion to bioenergy', Bioresource Technology, vol. 275, pp. 109-122.
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© 2018 Elsevier Ltd Ever-increasing swine wastewater (SW) has become a serious environmental concern. High levels of nutrients and toxic contaminants in SW significantly impact on the ecosystem and public health. On the other hand, swine wastewater is considered as valuable water and nutrient source for microalgae cultivation. The potential for converting the nutrients from SW into valuable biomass and then generating bioenergy from it has drawn increasing attention. For this reason, this review comprehensively discussed the biomass production, SW treatment efficiencies, and bioenergy generation potentials through cultivating microalgae in SW. Microalgae species grow well in SW with large amounts of biomass being produced, despite the impact of various parameters (e.g., nutrients and toxicants levels, cultivation conditions, and bacteria in SW). Pollutants in SW can effectively be removed by harvesting microalgae from SW, and the harvested microalgae biomass elicits high potential for conversion to valuable bioenergy.
Cheng, L, Song, W, Rao, Q, Zhou, J & Zhao, Z 2019, 'Bioaccumulation and toxicity of methoxychlor on Chinese mitten crab (Eriocheir sinensis)', Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, vol. 221, pp. 89-95.
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Chinese mitten crab, a featured macrobenthos, has been one of the most important economical aquatic species in China. This study assessed the accumulation of an organochlorine pesticide methoxychlor (MXC) in Chinese mitten crab during exposure to 1 mg/L of MXC. The results showed the residual concentration of MXC in the ovary and hepatopancreas reached 55.07 ± 2.64 ng/g and 34.51 ± 2.35 ng/g, respectively. After exposure, tubular vacuolization of epithelial tissues, condensed egg cells and obvious intervals between egg cell wall and stroma were observed in the hepatopancreas and ovary, respectively. Significant changes of three key metabolic enzymes in hepatopancreas were observed upon exposure to MXC. Compared to the control, acetylcholinesterase level was significantly higher at day 7 (0.15 ± 0.01 vs. 0.06 ± 0.00 U/mgprot); glutathione S-transferase level was elevated at both day 4 (12.01 ± 0.48 vs. 3.20 ± 0.44 U/mgprot) and day 7 (12.84 ± 1.01 vs. 8.22 ± 0.81 U/mgprot); superoxide dismutase was sharply increased at day 4 (21.20 ± 0.24 vs. 3.66 ± 0.60 U/mgprot) but decreased at day 7 (3.74 ± 0.12 vs. 9.44 ± 0.85 U/mgprot). Overall, dissolved MXC accumulated in lipid-rich tissues could cause damages on epithelial cells and egg cells and change metabolic activities of enzymes involved in antioxidative stress and detoxification processes.
Choi, J, Dorji, P, Shon, HK & Hong, S 2019, 'Applications of capacitive deionization: Desalination, softening, selective removal, and energy efficiency', Desalination, vol. 449, pp. 118-130.
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© 2018 Elsevier B.V. Capacitive deionization (CDI) has attracted a great attention as a promising desalination technology, and studies on CDI have increased significantly in the last ten years. However, there have been no guidelines for developing strategies involving CDI technology for specific applications. Therefore, our work presents a critical review of the recent advances in CDI to meet the technical requirements of various applicable areas, with an emphasis on hybrid systems. This paper first summarizes the major developments made on novel electrode materials for CDI for brackish water desalination. Then, CDI and reverse osmosis (RO) integrated systems are critically reviewed for both ultrapure water production and wastewater treatment. Additionally, the applicability of CDI on various industrial processes is discussed, covering two distinct topics: (1) water softening and (2) selective removal of valuable heavy metals and nutrients (nitrate/phosphate). Lastly, recent improvements on the energy efficiency of CDI processes are delineated, specifically focusing on energy recovery and hybridization with energy producing technology, such as reverse electrodialysis (RED) and microbial fuel cells (MFC). This review paper is expected to share the practical experience of CDI applications as well as to provide guidelines for electrode material development for each specific application.
Choi, Y, Naidu, G, Lee, S & Vigneswaran, S 2019, 'Effect of inorganic and organic compounds on the performance of fractional-submerged membrane distillation-crystallizer', Journal of Membrane Science, vol. 582, pp. 9-19.
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© 2019 Elsevier B.V. A novel approach - fractional-submerged membrane distillation crystallizer (F-SMDC) was evaluated for treating brine. F-SMDC is based on creating concentration gradient (CG) and temperature gradient (TG) in a reactor containing submerged hollow-fiber membrane. This enables water and salt recovery to occur simultaneously in a single reactor. The influence of inorganic and organic compounds present in brine solutions on the development and stability of CG/TG in F-SMDC was evaluated in detail in this study. The results of the study showed that properties of inorganic compounds - molecular weight and electronegativity played a significant role in influencing CG/TG in F-SMDC. A high CG ratio (between 1.51 and 1.83 after crystallization) was observed when using feed solutions with inorganic compounds such as KCl, MgSO4, and Na2SO4. However, only low CG ratio (between 0.94 and 1.46) was achieved in the case of feed solutions containing lower molecular weight compounds, NH4Cl and NaCl. The high CG ratio with KCl resulted in the occurrence of salt crystallization at a faster rate (from VCF 2.4 onwards) compared to the predicted theoretical salt saturation point of VCF 3.0. On the other hands, Na2SO4 showed lower flux decline (12.56% flux decline) compared to MgSO4 (55.93% flux decline) This was attributed to lower cation electronegativity of Na+. The presence of CG in F-SMDC by concentrated inorganic compounds also enhanced organic compounds to gravitate downwards to the bottom of the reactor, potentially mitigating organic deposition on the membrane.
Choi, Y, Naidu, G, Nghiem, LD, Lee, S & Vigneswaran, S 2019, 'Membrane distillation crystallization for brine mining and zero liquid discharge: opportunities, challenges, and recent progress', Environmental Science: Water Research & Technology, vol. 5, no. 7, pp. 1202-1221.
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This review outlines all the work done on the membrane distillation crystallization process.
Choi, Y, Ryu, S, Naidu, G, Lee, S & Vigneswaran, S 2019, 'Integrated submerged membrane distillation-adsorption system for rubidium recovery', Separation and Purification Technology, vol. 218, pp. 146-155.
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© 2019 Elsevier B.V. Seawater reverse osmosis (SWRO) brine management is essential for desalination. Improving brine recovery rate with resource recovery can enhance the overall desalination process. In this study, an integrated submerged membrane distillation (S-MD) with adsorption (granular potassium copper hexacyanoferrate (KCuFC)) was evaluated for improving water recovery from brine while extracting valuable Rb. The thermal S-MD process (55 °C) with a continuous supply of Rb-rich SWRO brine enabled Rb to be concentrated (99% rejection) while producing fresh water. Concentrated Rb in thermal condition enhanced Rb extraction by granular KCuFC. An optimum dose (0.24 g/L) KCuFC was identified based on 98% Rb mass adsorption (9.78 mg as Rb). The integrated submerged MD-adsorption system was able to achieve more than 85% water recovery and Rb extraction in continuous feed supply (in two cycles). Ca in SWRO brine resulted in CaSO4 deposition onto the membrane and surface of KCuFC, reducing recovery rate and Rb adsorption. MD water recovery significantly improved upon Ca removal while achieving a total of 6.65 mg of Rb extraction. In comparing the performance of different KCuFC forms (granular, particle and powder), the particle form of KCuFC exhibited 10–47% higher capacity in terms of total adsorbed Rb mass and adsorption rate.
Chong, CT, Mong, GR, Ng, J-H, Chong, WWF, Ani, FN, Lam, SS & Ong, HC 2019, 'Pyrolysis characteristics and kinetic studies of horse manure using thermogravimetric analysis', Energy Conversion and Management, vol. 180, pp. 1260-1267.
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Chong, W-T, Muzammil, WK, Ong, H-C, Sopian, K, Gwani, M, Fazlizan, A & Poh, S-C 2019, 'Performance analysis of the deflector integrated cross axis wind turbine', Renewable Energy, vol. 138, pp. 675-690.
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Chu Van, T, Zare, A, Jafari, M, Bodisco, TA, Surawski, N, Verma, P, Suara, K, Ristovski, Z, Rainey, T, Stevanovic, S & Brown, RJ 2019, 'Effect of cold start on engine performance and emissions from diesel engines using IMO-Compliant distillate fuels', Environmental Pollution, vol. 255, no. Pt 2, pp. 113260-113260.
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© 2019 Elsevier Ltd Emissions from ships at berth are small compared to the total ship emissions; however, they are one of the main contributors to pollutants in the air of densely-populated areas, consequently heavily affecting public health. This is due to auxiliary marine engines being used to generate electric power and steam for heating and providing services. The present study has been conducted on an engine representative of a marine auxiliary, which was a heavy duty, six-cylinder, turbocharged and after-cooled engine with a high pressure common rail injection system. Engine performance and emission characterisations during cold start are the focus of this paper, since cold start is significantly influential. Three tested fuels were used, including the reference diesel and two IMO (International Maritime Organization) compliant spiked fuels. The research engine was operated at a constant speed and 25% load condition after 12 h cooled soak. Results show that during cold start, significant heat generated from combustion is used to heat the engine block, coolant and lubricant. During the first minute, compared to the second minute, emissions of particle number (PN), carbon monoxide (CO), particulate matter (PM), and nitrogen oxides (NOx) were approximately 10, 4, 2 and 1.5 times higher, respectively. The engine control unit (ECU) plays a vital role in reducing engine emissions by changing the engine injection strategy based on the engine coolant temperature. IMO-compliant fuels, which were higher viscosity fuels associated with high sulphur content, resulted in an engine emission increase during cold start. It should be taken into account that auxiliary marine diesel engines, working at partial load conditions during cold start, contribute considerably to emissions in coastal areas. It demonstrates a need to implement practical measures, such as engine pre-heating, to obtain both environmental and public health advantages in coastal areas.
Dackermann, U, Smith, WA, Alamdari, MM, Li, J & Randall, RB 2019, 'Cepstrum-based damage identification in structures with progressive damage', Structural Health Monitoring, vol. 18, no. 1, pp. 87-102.
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This article aims at developing a new framework to identify and assess progressive structural damage. The method relies solely on output measurements to establish the frequency response functions of a structure using cepstrum-based operational modal analysis. Two different damage indicative features are constructed using the established frequency response functions. The first damage feature takes the residual frequency response function, defined as the difference in frequency response function between evolving states of the structure, and then reduces its dimension using principle component analysis; while in the second damage indicator, a new feature based on the area under the residual frequency response function curve is proposed. The rationale behind this feature lies in the fact that damage often affects a number of modes of the system, that is, it affects the frequency response function over a wide range of frequencies; as a result, this quantity has higher sensitivity to any structural change by combining all contributions from different frequencies. The obtained feature vectors serve as inputs to a novel multi-stage neural network ensemble designed to assess the severity of damage in the structure. The proposed method is validated using extensive experimental data from a laboratory four-girder timber bridge structure subjected to gradually progressing damage at various locations with different severities. In total, 13 different states of the structure are considered, and it is demonstrated that the new damage feature outperforms the conventional principle component analysis–based feature. The contribution of the work is threefold: first, the application of cepstrum-based operational modal analysis in structural health monitoring is further validated, which has potential for real-life applications where only limited knowledge of the input is available; second, a new damage feature is proposed and its superior performance is demonstrated;...
Dadzie, J, Runeson, G & Ding, G 2019, 'Assessing determinants of sustainable upgrade of existing buildings', Journal of Engineering, Design and Technology, vol. 18, no. 1, pp. 270-292.
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PurposeEstimates show that close to 90% of the buildings we will need in 2050 are already built and occupied. The increase in the existing building stock has affected energy consumption thereby negatively impacting the environment. The purpose of this paper is to assess determinants of sustainable upgrade of existing buildings through the adoption and application of sustainable technologies. The study also ranks sustainable technologies adopted by the professionals who participated in the survey with an in-built case study.Design/methodology/approachAs part of the overall methodology, a detailed literature review on the nature and characteristics of sustainable upgrade and the sustainable technologies adopted was undertaken. A survey questionnaire with an in-built case study was designed to examine all the sustainable technologies adopted to improve energy consumption in Australia. The survey was administered to sustainability consultants, architects, quantity surveyors, facility managers and engineers in Australia.FindingsThe results show a total of 24 technologies which are mostly adopted to improve energy consumption in existing buildings. A factor analysis shows the main components as: lighting and automation, heating, ventilation and air conditioning (HAVC) systems and equipment, envelope, renewable energy and passive technologies.Originality/valueThe findings bridge the gap in the literature on the adoption and application of sustainable technologies to upgrade existing buildings. The technologies can be adopted to reduce the excessive energy consumption patterns in ex...
Dai, Y, Chen, S-R, Chai, L, Zhao, J, Wang, Y & Wang, Y 2019, 'Overview of pharmacological activities of Andrographis paniculata and its major compound andrographolide', Critical Reviews in Food Science and Nutrition, vol. 59, no. sup1, pp. S17-S29.
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Damanik, Ong, Mofijur, Tong, Silitonga, Shamsuddin, Sebayang, Mahlia, Wang & Jang 2019, 'The Performance and Exhaust Emissions of a Diesel Engine Fuelled with Calophyllum inophyllum—Palm Biodiesel', Processes, vol. 7, no. 9, pp. 597-597.
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Nowadays, increased interest among the scientific community to explore the Calophyllum inophyllum as alternative fuels for diesel engines is observed. This research is about using mixed Calophyllum inophyllum-palm oil biodiesel production and evaluation that biodiesel in a diesel engine. The Calophyllum inophyllum–palm oil methyl ester (CPME) is processed using the following procedure: (1) the crude Calophyllum inophyllum and palm oils are mixed at the same ratio of 50:50 volume %, (2) degumming, (3) acid-catalysed esterification, (4) purification, and (5) alkaline-catalysed transesterification. The results are indeed encouraging which satisfy the international standards, CPME shows the high heating value (37.9 MJ/kg) but lower kinematic viscosity (4.50 mm2/s) due to change the fatty acid methyl ester (FAME) composition compared to Calophyllum inophyllum methyl ester (CIME). The average results show that the blended fuels have higher Brake Specific Fuel Consumption (BSFC) and NOx emissions, lower Brake Thermal Efficiency (BTE), along with CO and HC emissions than diesel fuel over the entire range of speeds. Among the blends, CPME5 offered better performance compared to other fuels. It can be recommended that the CPME blend has great potential as an alternative fuel because of its excellent characteristics, better performance, and less harmful emission than CIME blends.
Damtie, MM, Woo, YC, Kim, B, Hailemariam, RH, Park, K-D, Shon, HK, Park, C & Choi, J-S 2019, 'Removal of fluoride in membrane-based water and wastewater treatment technologies: Performance review', Journal of Environmental Management, vol. 251, pp. 109524-109524.
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The presence of excess fluoride in aqueous media above local environmental standards (e.g., the U.S. Environmental Protection Agency (EPA) standard of 4 mg/L) affects the health of aquatic life. Excess fluoride in drinking water above the maximum contaminant level (e.g., the World Health Organization (WHO) standard of 1.5 mg/L) also affects the skeletal and nervous systems of humans. Fluoride removal from aqueous solutions is difficult using conventional electrochemical, precipitation, and adsorption methods owing to its ionic size and reactivity. Thus, new technologies have been introduced to reduce the fluoride concentration in industrial wastewater effluents and various drinking water sources. Membrane technology is one of the newer technologies found to be very effective in significantly reducing fluoride to desired standards levels; however, it has received less attention than other technologies because it is perceived as a costly process. This study critically reviewed the performance of various membrane process and compared it with effluent and zero liquid discharge (ZLD) standards. The performance review has been conducted with the consideration of the theoretical background, rejection mechanisms, technical viability, and parameters affecting flux and rejection performance. This review includes membrane systems investigated for the defluoridation process but operated under pressure (i.e., reverse osmosis [RO] and nanofiltration [NF]), temperature gradients (i.e., membrane distillation [MD]), electrical potential gradients (i.e., electrodialysis [ED] and Donnan dialysis [DD]), and concentration differences (i.e., forward osmosis [FO]). Moreover, the study also addressed the advantages, limitations, & applicable conditions of each membrane based defluoridation process.
Dano, U, Balogun, A-L, Matori, A-N, Wan Yusouf, K, Abubakar, I, Said Mohamed, M, Aina, Y & Pradhan, B 2019, 'Flood Susceptibility Mapping Using GIS-Based Analytic Network Process: A Case Study of Perlis, Malaysia', Water, vol. 11, no. 3, pp. 615-615.
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Understanding factors associated with flood incidence could facilitate flood disaster control and management. This paper assesses flood susceptibility of Perlis, Malaysia for reducing and managing their impacts on people and the environment. The study used an integrated approach that combines geographic information system (GIS), analytic network process (ANP), and remote sensing (RS) derived variables for flood susceptibility assessment and mapping. Based on experts’ opinion solicited via ANP survey questionnaire, the ANP mathematical model was used to calculate the relative weights of the various flood influencing factors. The ArcGIS spatial analyst tools were used in generating flood susceptible zones. The study found zones that are very highly susceptible to flood (VHSF) and those highly susceptible to flood (HSF) covering 38.4% (30,924.6 ha) and 19.0% (15,341.1 ha) of the study area, respectively. The results were subjected to one-at-a-time (OAT) sensitivity analysis to verify their stability, where 6 out of the 22 flood scenarios correlated with the simulated spatial assessment of flood susceptibility. The findings were further validated using real-life flood incidences in the study area obtained from satellite images, which confirmed that most of the flooded areas were distributed over the VHSF and HSF zones. This integrated approach enables network model structuring, and reflects the interdependences among real-life flood influencing factors. This accurate identification of flood prone areas could serve as an early warning mechanism. The approach can be replicated in cities facing flood incidences in identifying areas susceptible to flooding for more effective flood disaster control.
Daqamseh, S, Al-Fugara, A, Pradhan, B, Al-Oraiqat, A & Habib, M 2019, 'MODIS Derived Sea Surface Salinity, Temperature, and Chlorophyll-a Data for Potential Fish Zone Mapping: West Red Sea Coastal Areas, Saudi Arabia', Sensors, vol. 19, no. 9, pp. 2069-2069.
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In this study, a multi-linear regression model for potential fishing zone (PFZ) mapping along the Saudi Arabian Red Sea coasts of Yanbu’ al Bahr and Jeddah was developed, using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data derived parameters, such as sea surface salinity (SSS), sea surface temperature (SST), and chlorophyll-a (Chl-a). MODIS data was also used to validate the model. The model expanded on previous models by taking seasonal variances in PFZs into account, examining the impact of the summer, winter, monsoon, and inter-monsoon season on the selected oceanographic parameters in order to gain a deeper understanding of fish aggregation patterns. MODIS images were used to effectively extract SSS, SST, and Chl-a data for PFZ mapping. MODIS data were then used to perform multiple linear regression analysis in order to generate SSS, SST, and Chl-a estimates, with the estimates validated against in-situ data obtained from field visits completed at the time of the satellite passes. The proposed model demonstrates high potential for use in the Red Sea region, with a high level of congruence found between mapped PFZ areas and fish catch data (R2 = 0.91). Based on the results of this research, it is suggested that the proposed PFZ model is used to support fisheries in determining high potential fishing zones, allowing large areas of the Red Sea to be utilized over a short period. The proposed PFZ model can contribute significantly to the understanding of seasonal fishing activity and support the efficient, effective, and responsible use of resources within the fishing industry.
Darabi, H, Choubin, B, Rahmati, O, Torabi Haghighi, A, Pradhan, B & Kløve, B 2019, 'Urban flood risk mapping using the GARP and QUEST models: A comparative study of machine learning techniques', Journal of Hydrology, vol. 569, pp. 142-154.
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© 2018 Elsevier B.V. Flood risk mapping and modeling is important to prevent urban flood damage. In this study, a flood risk map was produced with limited hydrological and hydraulic data using two state-of-the-art machine learning models: Genetic Algorithm Rule-Set Production (GARP) and Quick Unbiased Efficient Statistical Tree (QUEST). The flood conditioning factors used in modeling were: precipitation, slope, curve number, distance to river, distance to channel, depth to groundwater, land use, and elevation. Based on available reports and field surveys for Sari city (Iran), 113 points were identified as flooded areas (with each flooded zone assigned a value of 1). Different conditioning factors, including urban density, quality of buildings, age of buildings, population density, and socio-economic conditions, were taken into account to analyze flood vulnerability. In addition, the weight of these conditioning factors was determined based on expert knowledge and Fuzzy Analytical Network Process (FANP). An urban flood risk map was then produced using flood hazard and flood vulnerability maps. The area under the receiver-operator characteristic curve (AUC-ROC) and Kappa statistic were applied to evaluate model performance. The results demonstrated that the GARP model (AUC-ROC = 93.5%, Kappa = 0.86) had higher performance accuracy than the QUEST model (AUC-ROC = 89.2%, Kappa = 0.79). The results also indicated that distance to channel, land use, and elevation played major roles in flood hazard determination, whereas population density, quality of buildings, and urban density were the most important factors in terms of vulnerability. These findings demonstrate that machine learning models can help in flood risk mapping, especially in areas where detailed hydraulic and hydrological data are not available.
Dash, SK, Saikia, R & Nimbalkar, S 2019, 'Contact Pressure Distribution on Subgrade Soil Underlying Geocell Reinforced Foundation Beds', Frontiers in Built Environment, vol. 5.
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© Copyright © 2019 Dash, Saikia and Nimbalkar. High contact stresses generated in the foundation soil, owing to increased load, causes distress, instability, and large settlements. Present days, geocell reinforcement is being widely used for the performance improvement of foundation beds. Pressure distribution on subgrade soil in geocell reinforced foundation beds is studied through model tests and numerical analysis. The test data indicates that with provision of geocell reinforcement the contact pressure on the subgrade soil reduces significantly. Consequently, the subgrade soil tends to remain intact until large loadings on the foundation leading to significant performance improvement. Through numerical analysis it is observed that the geocells in the region under the footing were subjected to compression and beyond were in tension. This indicates that the geocell reinforcement right under the footing directly sustains the footing loading through mobilization of its compressive stiffness and bending rigidity. Whereas, the end portions of the geocell reinforcement, contribute to the performance improvement in a secondary manner through mobilization of anchorage derived from soil passive resistance and friction.
De Carvalho Gomes, S, Zhou, JL, Li, W & Long, G 2019, 'Progress in manufacture and properties of construction materials incorporating water treatment sludge: A review', Resources, Conservation and Recycling, vol. 145, pp. 148-159.
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© 2019 Elsevier B.V. Water treatment sludge (WTS) management is a growing global problem for water treatment plants (WTPs) and governments. Considering the scarcity of raw materials in many parts of the planet and unique properties of WTS, extensive research has been conducted on the application of WTS in the production of construction materials such as roof tiles, bricks, lightweight aggregates, cement, concrete and geopolymers. This paper critically reviews the progress in the application of WTS in construction materials, by synthesizing results from recent studies. Research findings have revealed that incorporation of ≤10% alum-based sludge in ceramic bricks is satisfactory with a small reduction of mechanical performance. Using the iron-based sludge, the bricks presented better mechanical strength than the reference clay-bricks. Concerning WTS application in concrete, 5% replacement of cement or sand by WTS was considered as the ideal value for the application in a variety of structural and non-structural concrete without adverse effect on concrete mechanical performance. Furthermore, this paper discusses sludge-amended concrete in terms of durability, potential leaching of toxic elements and cost, and suggests topics for future research on the sustainable management of WTS.
de Moura, PK, Cavalli, CB & da Rocha, CG 2019, 'Interface design for in-home displays', Sustainable Production and Consumption, vol. 18, pp. 130-144.
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© 2018 Institution of Chemical Engineers In-home displays can support behavioral changes by providing users with real time information (or feedback) on their energy consumption. Previous studies have shown that the design of such devices plays an important role in effectively communicating such information to users and that preferences are culturally-depend. This paper examines information elements best suited to the Brazilian context for children, adults, and elderly. It explores the preference, ranking, and understanding in addition to the ideal in-home display for each user profile. Lastly, display prototypes suited to each user profile are also proposed based on the results of seven focus groups totaling fifty participants. Real-time consumption was one of the most important information whereas penalty was the least. All participants preferred historical comparison to normative comparison. Numerical formats were better understood than ambient formats for real-time consumption. In addition, children and adults preferred and designed ambient formats whereas elderly preferred numerical information in monetary unit. Elderly would like to keep the display simple whereas adults and children need more interactive designs. These findings contribute to more effective in-home display design particularly for the Brazilian context, where smart meter and in home-displays are not extensively adopted.
Deng, L, Ngo, H-H, Guo, W & Zhang, H 2019, 'Pre-coagulation coupled with sponge-membrane filtration for organic matter removal and membrane fouling control during drinking water treatment', Water Research, vol. 157, pp. 155-166.
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© 2019 Elsevier Ltd A new hybrid system was developed in this study for the treatment of drinking water consisting of pre-coagulation using polyaluminium chloride (PACl) and membrane filtration (MF) with sponge cubes acting as biomass carriers (P-SMF). When compared to a conventional MF (CMF) and a MF after coagulation by utilizing PACl (P-MF), better removal of nutrients, UV254 and dissolved organic carbon (DOC) (>65%) was obtained from the P-SMF. The accumulation of biopolymers (including polysaccharides and proteins), humic substances, hydrophilic organics, and other small molecular weight (MW) organic matter in the CMF led to the most severe membrane fouling coupled with the highest pore blocking and cake resistance. Pre-coagulation was ineffective in eliminating small MW and hydrophilic organic matter. Conversely, the larger MW organics (i.e. biopolymers and humic substances), small MW organics and hydrophilic organic compounds could be removed in significantly larger quantities in the P-SMF by PACl coagulation. This was achieved via adsorption and the biodegradation by attached biomass on these sponges and by the suspended sludge. Further analyses of the microbial community indicated that the combined addition of PACl and sponges generated a high enrichment of Zoolgloea, Amaricoccus and Reyranella leading to the reduction of biopolymers, and Flexibacter and Sphingobium were linked to the degradation of humic substances. Moreover, some members of Alphaproteobacteria in the P-SMF may be responsible for the removal of low MW organics. These results suggest that the pre-coagulation process coupled with adding sponge in the MF system is a promising technology for mitigating membrane fouling.
Dikshit, A, Sarkar, R, Pradhan, B, Acharya, S & Dorji, K 2019, 'Estimating Rainfall Thresholds for Landslide Occurrence in the Bhutan Himalayas', Water, vol. 11, no. 8, pp. 1616-1616.
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Consistently over the years, particularly during monsoon seasons, landslides and related geohazards in Bhutan are causing enormous damage to human lives, property, and road networks. The determination of thresholds for rainfall triggered landslides is one of the most effective methods to develop an early warning system. Such thresholds are determined using a variety of rainfall parameters and have been successfully calculated for various regions of the world at different scales. Such thresholds can be used to forecast landslide events which could help in issuing an alert to civic authorities. A comprehensive study on the determination of rainfall thresholds characterizing landslide events for Bhutan is lacking. This paper focuses on defining event rainfall–duration thresholds for Chukha Dzongkhag, situated in south-west Bhutan. The study area is chosen due to the increase in frequency of landslides during monsoon along Phuentsholing-Thimphu highway, which passes through it and this highway is a major trade route of the country with the rest of the world. The present threshold method revolves around the use of a power law equation to determine event rainfall–duration thresholds. The thresholds have been established using available rainfall and landslide data for 2004–2014. The calculated threshold relationship is fitted to the lower boundary of the rainfall conditions leading to landslides and plotted in logarithmic coordinates. The results show that a rainfall event of 24 h with a cumulated rainfall of 53 mm can cause landslides. Later on, the outcome of antecedent rainfall varying from 3–30 days was also analysed to understand its effect on landslide incidences based on cumulative event rainfall. It is also observed that a minimum 10-day antecedent rainfall of 88 mm and a 20-day antecedent rainfall of 142 mm is required for landslide occurrence in the area. The thresholds presented can be improved with the availability of hourly rainfall data a...
Dikshit, A, Satyam, N & Pradhan, B 2019, 'Estimation of Rainfall-Induced Landslides Using the TRIGRS Model', Earth Systems and Environment, vol. 3, no. 3, pp. 575-584.
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© 2019, King Abdulaziz University and Springer Nature Switzerland AG. Rainfall-induced landslides have become the biggest threat in the Indian Himalayas and their increasing frequency has led to serious calamities. Several models have been built using various rainfall characteristics to determine the minimum rainfall amount for landslide occurrences. The utilisation of such models depends on the quality of available landslide and rainfall data. However, these models do not consider the effect of local soil, geology, hydrology and topography, which varies spatially. This study is to analyse the triggering process for shallow landslides using physical-based models for the Indian Himalayan region. This research focuses on the utilisation and dependability of physical models in the Kalimpong area of Darjeeling Himalayas, India. The approach utilised the transient rainfall infiltration and grid-based regional slope-stability (TRIGRS) model, which is a widely used model in assessing the variations in pore water pressure and determining the change in the factor of safety. TRIGRS uses an infinite slope model to calculate the change in the factor of safety for every pixel. Moreover, TRIGRS is used to compare historical rainfall scenarios with available landslide database. This study selected the rainfall event from 30th June to 1st July 2015 as input for calibration because the amount of rainfall in this period was higher than the monthly average and caused 18 landslides. TRIGRS depicted variations in the factor of safety with duration before, during and after the heavy rainfall event in 2015. This study further analysed the landslide event and evaluated the predictive capability using receiver operating characteristics. The model was able to successfully predict 71.65% of stable pixels after the landslide event, however, the availability of more datasets such as hourly rainfall, accurate time of landslide event would further improve the results. The results from this stu...
Ding, A, Lin, D, Zhao, Y, Ngo, HH, Guo, W, Bai, L, Luo, X, Li, G, Ren, N & Liang, H 2019, 'Effect of metabolic uncoupler, 2,4‑dinitrophenol (DNP) on sludge properties and fouling potential in ultrafiltration membrane process', Science of The Total Environment, vol. 650, no. Pt 2, pp. 1882-1888.
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© 2018 Elsevier B.V. Energy uncoupling technology was applied to the membrane process to control the problem of bio-fouling. Different dosages of uncoupler (2,4‑dinitrophenol, DNP) were added to the activated sludge, and a short-term ultrafiltration test was systematically investigated for analyzing membrane fouling potential and underlying mechanisms. Ultrafiltration membrane was used and made of polyether-sulfone with a molecular weight cut off (MWCO) of 150 kDa. Results indicated that low DNP concentration (15–30 mg/g VSS) aggravated membrane fouling because more soluble microbial products were released and then rejected by the membrane, which significantly increased cake layer resistance compared with the control. Conversely, a high dosage of DNP (45 mg/g VSS) retarded membrane fouling owing to the high inhibition of extracellular polymeric substances (proteins and polysaccharides) of the sludge, which effectively prevented the formation of cake layer on the membrane surface. Furthermore, analyses of fouling model revealed that a high dosage of DNP delayed the fouling model from pore blocking transition to cake filtration, whereas this transition process was accelerated in the low dosage scenario.
Ding, G & Ying, X 2019, 'Embodied and operating energy assessment of existing buildings – Demolish or rebuild', Energy, vol. 182, pp. 623-631.
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© 2019 Addressing climate change and energy efficiency of buildings challenge governments. Research studies to improve the efficiency of new buildings are many, but the potential of existing buildings to alleviate environmental problems is yet to be recognised. The economic development in China triggered the rapid growth of population and urbanisation. The government has experienced severe environmental problems due, among other things, to an increasing demand for housing. The demand for housing and environmental degradation have compelled the government to demolish historic houses for the construction of more efficient residential buildings. Nevertheless, the consumption of natural resources is essential considerations for redevelopment. The research has selected a south China town to conduct multiple case studies to analyse and compare the energy efficiency of historic and modern dwellings. The research reveals that modern building overall outperforms the historic houses in energy consumption for heating but consumes much higher energy for cooling over a 12-month period. However, the historic houses outperform the modern building in the embodied energy and carbon analysis. If these historic houses are to be replaced with energy efficient buildings, it will take approximately 18–41 years to recover the embodied energy invested in the materials for the new buildings.
Ding, W, Jin, W, Cao, S, Zhou, X, Wang, C, Jiang, Q, Huang, H, Tu, R, Han, S-F & Wang, Q 2019, 'Ozone disinfection of chlorine-resistant bacteria in drinking water', Water Research, vol. 160, pp. 339-349.
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© 2019 Elsevier Ltd The wide application of chlorine disinfectant for drinking water treatment has led to the appearance of chlorine-resistant bacteria, which pose a severe threat to public health. This study was performed to explore the physiological-biochemical characteristics and environmental influence (pH, temperature, and turbidity)of seven strains of chlorine-resistant bacteria isolated from drinking water. Ozone disinfection was used to investigate the inactivation effect of bacteria and spores. The DNA concentration and cell surface structure variations of typical chlorine-resistant spores (Bacillus cereus spores)were also analysed by real-time qPCR, flow cytometry, and scanning electron microscopy to determine their inactivation mechanisms. The ozone resistance of bacteria (Aeromonas jandaei < Vogesella perlucida < Pelomonas < Bacillus cereus < Aeromonas sobria)was lower than that of spores (Bacillus alvei < Lysinibacillus fusiformis < Bacillus cereus)at an ozone concentration of 1.5 mg/L. More than 99.9% of Bacillus cereus spores were inactivated by increasing ozone concentration and treatment duration. Moreover, the DNA content of Bacillus cereus spores decreased sharply, but approximately 1/4 of the target genes remained. The spore structure exhibited shrinkage and folding after ozone treatment. Both cell structures and gene fragments were damaged by ozone disinfection. These results showed that ozone disinfection is a promising method for inactivating chlorine-resistant bacteria and spores in drinking water.
Ding, X, Wei, D, Guo, W, Wang, B, Meng, Z, Feng, R, Du, B & Wei, Q 2019, 'Biological denitrification in an anoxic sequencing batch biofilm reactor: Performance evaluation, nitrous oxide emission and microbial community', Bioresource Technology, vol. 285, pp. 121359-121359.
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Dong, B, Xia, Z, Sun, J, Dai, X, Chen, X & Ni, B-J 2019, 'The inhibitory impacts of nano-graphene oxide on methane production from waste activated sludge in anaerobic digestion', Science of The Total Environment, vol. 646, pp. 1376-1384.
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© 2018 The wide application of graphene oxide nanoparticles inevitably leads to their discharge into wastewater treatment plants and combination with the activated sludge. However, to date, it is largely unknown if the nano-graphene oxide (NGO) has potential impacts on the anaerobic digestion of waste activated sludge (WAS). Therefore, this work aims to fill the knowledge gap through comprehensively investigating the effects of NGO on carbon transformation and methane production in the anaerobic digestion of WAS. Biochemical methane potential tests demonstrated the methane production dropped with increasing NGO additions, the cumulative methane production decreasing by 7.6% and 12.6% at the NGO dosing rates of 0.054 mg/mg-VS and 0.108 mg/mg-VS, respectively. Model-based analysis indicated NGO significantly reduced biochemical methane potential, with the highest biochemical methane potential decrease being approximately 10% at the highest NGO dosing rate. Further experimental analysis suggested that the decreased methane production was firstly related to a decrease in soluble organic substrates availability during the process of sludge disintegration, potentially attributing to the strong absorption of organic substrates by NGO. Secondly, NGO significantly inhibited the methanogenesis by negatively affecting the corresponding enzyme activity (i.e. coenzyme F420), which could also resulted in a decreased methane production.
Dong, W, Li, W, Long, G, Tao, Z, Li, J & Wang, K 2019, 'Electrical resistivity and mechanical properties of cementitious composite incorporating conductive rubber fibres', Smart Materials and Structures, vol. 28, no. 8, pp. 085013-085013.
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© 2019 IOP Publishing Ltd. Conductive cementitious composites with excellent conductivity and piezoresistivity can be potentially used for pavement deicing, concrete corrosion evaluations or structural health monitoring. Inspired by the practice of recycling rubber wastes for concrete manufacturing, the conductive rubbers are first added as enhanced fillers to improve the electrical conductivity of cementitious composite in this study. Based on the experimental investigations on electrical resistivity, mechanical properties and microstructure, the results show that cementitious composites containing conductive rubber fibres exhibit relatively low resistivity with nearly one order of magnitude to approximately 1 × 104 Ω cm. On the other hand, cementitious composites with aluminium/silver filled rubber (AR) exhibit better conductivity than the counterparts with carbon black filled rubber (CR). For CR reinforced composites (CRC) and AR reinforced composite (ARC) with more than 40 rubber fibres (0.64 vol%), the higher the rubber fibre content, the better is the conductivity but the slightly lower the compressive strength. The cementitious composites reinforced by 100 conductive rubber fibres (1.6 vol%) not only display excellent conductivity but also provides acceptable mechanical properties, with up to 30.6% increase in ultimate strain but only 17.3% reduction in compressive strength. Furthermore, cementitious composites with rubber fibres demonstrate better damping capacity by enlarging stress-strain hysteresis loops compared to the counterpart without rubber. Such promising conductivity and damping properties provide the cementitious composites with great potentials for being used as cementitious composite sensors and smart composites to self-monitor the structural health or traffic load of various transportation infrastructures, such as bridges, highways and pavements.
Dong, W, Li, W, Lu, N, Qu, F, Vessalas, K & Sheng, D 2019, 'Piezoresistive behaviours of cement-based sensor with carbon black subjected to various temperature and water content', Composites Part B: Engineering, vol. 178, pp. 107488-107488.
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© 2019 Elsevier Ltd Cement-based sensor possesses unique properties for structural health monitoring (SHM) applications, such as low cost, high durability, adaptability and excellent sensitivity. The piezoresistivity of cement-based sensor possesses is often affected by working environments, which may limit its real potentials. In this study, the piezoresistive sensitivity and repeatability of cement-based sensors with carbon black (CB) under various environmental conditions were investigated. Under various temperatures ranging from −20 °C to 100 °C, the piezoresistive sensitivity and repeatability were almost unchanged when eliminating the effects by thermal exchanges. The water content of cementitious composites caused significant fluctuations on the resistivity and piezoresistivity, and the optimal water content for cement-based sensor possesses was found to be approximately 8%. Subjected to freeze-thaw cycles, dry CB/cementitious composites slightly reduced the piezoresistive sensitivity. However, the saturated composites presented dramatic piezoresistivity reduction by 30.7%, due to the microstructural damages caused by the volume expansion and shrinkage of pore solution. The related outcomes provide scientific framework for the adoption of CB/cementitious composites sensors for the SHM of concrete infrastructures under various environmental conditions.
Dong, W, Li, W, Shen, L & Sheng, D 2019, 'Piezoresistive behaviours of carbon black cement-based sensors with layer-distributed conductive rubber fibres', Materials & Design, vol. 182, pp. 108012-108012.
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© 2019 Conductive rubber fibres filled carbon black (CB)/cementitious composites were developed to achieve the cement-based sensors with excellent piezoresistivity in this study. Ameliorations on the conductivity and piezoresistive sensitivity of CB filled composites were mainly explored with conductive rubber fibres embedded. Their compressive strengths were investigated to evaluate the practical application possibility. The results indicated that the composites with CB content <4.0 wt% possessed acceptable compressive strengths. In terms of conductivity and piezoresistivity, both conductivity and piezoresistivity of composites filled with 0.5 wt% CB increased with the rubber content, and their gauge factor raised to 91 when embedded with 80 rubber fibres (1.27 vol%). Moreover, phenomenon of “piezoresistive percolation” was observed by sharp fractional changes of resistivity for the composites filled with 1.0 wt% CB, where existed highest gauge factor reaching 482 when embedded with same rubber fibres. However, because of the excellent conductivity of 2.0 wt% CB filled composites, the gauge factor firstly increased but then slightly decreased around 100 with increase of rubber fibre content. Overall, conductive rubber fibres can significantly improve the piezoresistivity of CB/cementitious composites by the increased gauge factor.
Dong, W, Li, W, Tao, Z & Wang, K 2019, 'Piezoresistive properties of cement-based sensors: Review and perspective', Construction and Building Materials, vol. 203, pp. 146-163.
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© 2019 Elsevier Ltd Cement-based sensors are increasingly used in smart concrete to self-sense and monitor the damages and cracks through the measurements of concrete electrical resistivity. The fundamental concepts, key components, manufacturing process, piezoresistivity measurements, and primary applications of cement-based sensors are reviewed in this paper. Various materials, mechanical and environmental factors affecting concrete piezoresistive properties are explicated. Some contradictory results from different studies are reported and discussed. Future perspectives of piezoresistive cement-based sensors are also delineated. The review reveals that there is an optimal conductor content, below which the sensor would perform more like plain concrete with high resistivity and low sensitivity, while excessively higher than which, the dispersion of the conductive phase could become difficult, thus increasing resistivity. The manufacturing process, such as the dispersion method of conductors and curing condition, plays a significant role in conductor distribution, matrix density and pore structure of the sensors, which, together with rheology of the sensor composite, consequently alters the piezoresistive properties of the sensors. In addition to responding to mechanical loading, cement-based piezoresistive sensor also has a great potential for monitoring behaviour of concrete under freeze-thaw cycling. It is expected that this review will provide not only an orientation for new researchers to explore and engage in related studies but also an insight for experienced researchers to perform transformational examinations into cement-based piezoresistive sensors.
Dorji, P, Kim, DI, Jiang, J, Choi, J, Phuntsho, S, Hong, S & Shon, HK 2019, 'Bromide and iodide selectivity in membrane capacitive deionisation, and its potential application to reduce the formation of disinfection by-products in water treatment', Chemosphere, vol. 234, pp. 536-544.
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© 2019 Elsevier Ltd The formation of toxic disinfection by-products during water disinfection due to the presence of bromide and iodide is a major concern. Current treatment technologies such as membrane, adsorption and electrochemical processes have been known to have limitations such as high energy demand and excessive chemical use. In this study, the selectivity between bromide and iodide, and their removal in membrane capacitive deionisation (MCDI) was evaluated. The results showed that iodide was more selectively removed over bromide from several binary feed waters containing bromide and iodide under various initial concentrations and applied voltages. Even in the presence of significant background concentration of sodium chloride, definite selectivity of iodide over bromide was observed. The high partial-charge transfer coefficient of iodide compared to bromide could be a feasible explanation for high iodide selectivity since both bromide and iodide have similar ionic charge and hydrated radius. The result also shows that MCDI can be a potential alternative for the removal of bromide and iodide during water treatment.
Dorji, U, Tenzin, UM, Dorji, P, Wangchuk, U, Tshering, G, Dorji, C, Shon, H, Nyarko, KB & Phuntsho, S 2019, 'Wastewater management in urban Bhutan: Assessing the current practices and challenges', Process Safety and Environmental Protection, vol. 132, pp. 82-93.
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© 2019 Institution of Chemical Engineers This study reviews the current wastewater management practices and their challenges in urban Bhutan. The study data was collected from the local authorities of 35 classified towns, and the field survey was conducted for the two representative towns of Thimphu City and Khuruthang town. The study observed that only eight of the 35 classified towns (22.8%) have public sewerage systems, with an average coverage of 19.7% of Bhutan's total urban population, or 7.4% of Bhutan's entire population. The imported modular wastewater treatment technology was significantly more expensive than alternative options; however, approximately six towns have already adopted this technology, due to a lack of space for a much cheaper waste stabilisation ponds. Currently, over 80% of Bhutan's urban population depends on the on-site sanitation system for their domestic wastewater disposal; however, over 40% of these properties lacked a soak-pit system for the safe disposal of septic tank effluent. Therefore, this study indicates that urban settlements in Bhutan are potentially subjected to overflow of significant amount of hazardous septic tank effluents directly into the environment posing significant risk to public and the environment. A critical urban plot space analysis indicates that the current system of on-site sanitation is inadequate and unsuitable for the current urban settings. Since it is impractical for the government to provide public sewerage system to all the towns, a low-cost public sewerage system, or an alternative and improved on-site treatment system, needs to be explored and promoted to achieve long-term environmental objectives.
Duan, H, Ye, L, Wang, Q, Zheng, M, Lu, X, Wang, Z & Yuan, Z 2019, 'Nitrite oxidizing bacteria (NOB) contained in influent deteriorate mainstream NOB suppression by sidestream inactivation', Water Research, vol. 162, pp. 331-338.
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© 2019 Sidestream sludge treatment approaches have been developed in recent years to achieve mainstream nitrite shunt or partial nitritation, where NOB are selectively inactivated by biocidal factors such as free nitrous acid (FNA) or free ammonium (FA) in a sidestream reactor. The existence of NOB in raw wastewater has been increasingly realized and could pose critical challenge to stable NOB suppressions in those systems. This study, for the first time, evaluated the impact of influent NOB on the NOB suppressions in a mainstream nitrite shunt system achieved through sidestream sludge treatment. An over 500-day sequential batch reactor operation with six experimental phases rigorously demonstrated the negative effects of influent NOB on mainstream NOB control. Continuously seeding of NOB contained in influent stimulated NOB community shifts, leading to different extents of ineffective NOB suppression. The role of primary wastewater treatment in NOB removal from raw wastewater was also investigated. Results suggest primary settling and High Rate Activated Sludge system could remove a large part of NOB contained in raw wastewater. Primary treatment for raw wastewater is necessary for ensuring stable mainstream NOB suppressions.
Duong, HC, Ansari, AJ, Nghiem, LD, Cao, HT, Vu, TD & Nguyen, TP 2019, 'Membrane Processes for the Regeneration of Liquid Desiccant Solution for Air Conditioning', Current Pollution Reports, vol. 5, no. 4, pp. 308-318.
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© 2019, Springer Nature Switzerland AG. Purpose of Review: Regeneration of liquid desiccant solutions is critical for the liquid desiccant air conditioning (LDAC) process. In most LDAC systems, the weak desiccant solution is regenerated using the energy-intensive thermal evaporation method which suffers from desiccant carry-over. Recently, membrane processes have gained increasing interest as a promising method for liquid desiccant solution regeneration. This paper provides a comprehensive review on the applications of membrane processes for regeneration of liquid desiccant solutions. Fundamental knowledge, working principles, and the applications of four key membrane processes (e.g., reverse osmosis (RO), forward osmosis (FO), electrodialysis (ED), and membrane distillation (MD)) are discussed to shed light on their feasibility for liquid desiccant solution regeneration and the associated challenges. Recent Findings: RO is effective at preventing desiccant carry-over; however, current RO membranes are not compatible with hypersaline liquid desiccant solutions. FO deploys a concentrated draw solution to overcome the high osmotic pressure of liquid desiccant solutions; hence, it is feasible for their regeneration despite the issues with internal/external concentration polarization and reverse salt flux. ED has proven its technical feasibility for liquid desiccant solution regeneration; nevertheless, more research into the process energy efficiency and the recycling of spent solution are recommended. Finally, as a thermally driven process, MD is capable of regenerating liquid desiccant solutions, but it is adversely affected by the polarization effects associated with the hypersalinity of the solutions. Summary: Extensive studies are required to realize the applications of membrane processes for the regeneration of liquid desiccant solutions used for LDAC systems.
Duong, HC, Pham, TM, Luong, ST, Nguyen, KV, Nguyen, DT, Ansari, AJ & Nghiem, LD 2019, 'A novel application of membrane distillation to facilitate nickel recovery from electroplating wastewater', Environmental Science and Pollution Research, vol. 26, no. 23, pp. 23407-23415.
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© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. In many years, the nickel electroplating technique has been applied to coat nickel on other materials for their increased properties. Nickel electroplating has played a vital role in our modern society but also caused considerable environmental concerns due to the mass discharge of its wastewater (i.e. containing nickel and other heavy metals) to the environment. Thus, there is a growing need for treating nickel electroplating wastewater to protect the environment and, in tandem, recover nickel for beneficial use. This study explores a novel application of membrane distillation (MD) for the treatment of nickel electroplating wastewater for a dual purpose: facilitating the nickel recovery and obtaining fresh water. The experimental results demonstrate the technical capability of MD to pre-concentrate nickel in the wastewater (i.e. hence pave the way for subsequent nickel recovery via chemical precipitation or electrodeposition) and extract fresh water. At a low operating feed temperature of 60 °C, the MD process increased the nickel content in the wastewater by more than 100-fold from 0.31 to 33 g/L with only a 20% reduction in the process water flux and obtained pure fresh water. At such high concentration factors, the membrane surface was slightly fouled by inorganic precipitates; however, membrane pore wetting was not evident, confirmed by the purity of the obtained fresh water. The fouled membrane was effectively cleaned using a 3% HCl solution to restore its surface morphology. Finally, the preliminary thermal energy analysis of the combined MD–chemical precipitation/electrodeposition process reveals a considerable reduction in energy consumption of the nickel recovery process.
Duong, HC, Tran, TL, Ansari, AJ, Cao, HT, Vu, TD & Do, K-U 2019, 'Advances in Membrane Materials and Processes for Desalination of Brackish Water', Current Pollution Reports, vol. 5, no. 4, pp. 319-336.
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Eder, K, Otter, LM, Yang, L, Jacob, DE & Cairney, JM 2019, 'Overcoming Challenges Associated with the Analysis of Nacre by Atom Probe Tomography', Geostandards and Geoanalytical Research, vol. 43, no. 3, pp. 385-395.
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In this study atom probe tomography was used to study nacre, an important biocomposite material that is challenging to prepare and analyse by atom probe and, when successful, yields data that is challenging to interpret. It was found that these challenges mainly arise from the insulating and heterogeneous nano‐scale properties of nacre. We outline our current best practice for preparing and running atom probe tips, such as using a low acceleration voltage (< 3 kV) and current (≤ 50 pA) to avoid damage to the microstructure, and using transmission electron microscopy to confirm that the region of interest is located close to the apex of the atom probe tip. Optimisation of the preparation parameters led to several successful atom probe experiments, with one of the data sets containing part of an organic membrane and others showing organic inclusions within the reconstruction.
Eeshwarasinghe, D, Loganathan, P & Vigneswaran, S 2019, 'Simultaneous removal of polycyclic aromatic hydrocarbons and heavy metals from water using granular activated carbon', Chemosphere, vol. 223, pp. 616-627.
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© 2019 Elsevier Ltd Polycyclic aromatic hydrocarbons (PAHs) and heavy metals are dangerous pollutants that commonly co-occur in water. An adsorption study conducted on the simultaneous removal of PAHs (acenaphthylene, phenanthrene) and heavy metals (Cd, Cu, Zn) by granular activated carbon (GAC) showed that, when these pollutants are present together, their adsorption was less than when they were present individually. The adsorptive removal percentage of PAHs (initial concentration 1 mg/L) was much higher than that of heavy metals (initial concentration (20 mg/L). The reduction in adsorption of PAHs by heavy metals followed the heavy metals' adsorption capacity and reduction in the negative zeta potential of GAC order (Cu > Zn > Cd). In contrast, PAHs had little effect on the zeta potential of GAC. The Langmuir adsorption capacities of acenaphthylene (0.31–2.63 mg/g) and phenanthrene (0.74–7.36 mg/g) on GAC decreased with increased metals' concentration with the reduction following the order of the metals’ adsorption capacity. The kinetic adsorption data fitted to Weber and Morris plots, indicating intra-particle diffusion of both PAHs and heavy metals into the mesopores and micropores in GAC with the diffusion rates. This depended on the type of PAH and metal and whether the pollutants were present alone or together.
Ekanayake, D, Aryal, R, Hasan Johir, MA, Loganathan, P, Bush, C, Kandasamy, J & Vigneswaran, S 2019, 'Interrelationship among the pollutants in stormwater in an urban catchment and first flush identification using UV spectroscopy', Chemosphere, vol. 233, pp. 245-251.
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© 2019 Elsevier Ltd Assessing urban stormwater quality by investigation and characterisation of pollutants is a prerequisite for its effective management, for reuse and safe discharge. The stochastic nature of rainfall, dry weather periods, topology, human activities and climatic conditions generate and wash-off pollutants differently from event to event. This study investigated the major physico-chemical pollutants in stormwater runoff collected from an urban catchment over a period of two years. The aim of this study was to explore the use of UV spectroscopy to identify the first flush. In this study, the variation of pollutants during the passage of a rain event and the relationships among the measured pollutants was analysed to help broaden the application of UV spectroscopy beyond the detection of organic matter. Correlation analysis and principal component analysis (PCA) were performed to identify the possible relationship among measured pollutants. Although correlation analysis revealed some relationships between pollutants, in general they were not strong enough and was not helpful. PCA biplots suggested a few groups and revealed that the two components model could explain nearly 72% of the variability between pollutants. Pollutants in the group that included dissolved organic carbon (DOC) behaved in a similar manner. UV spectroscopy was applied to identify the first flush by comparing the recorded spectrum of consecutive samples that were collected in an event. Analysis of the spectra was able to isolate the point when first flush ends for DOC and pollutants that behave similar to it.
Fahmi, Rahman, Ong, Jan, Kusumo, Sebayang, Husin, Silitonga, Mahlia & Rahman 2019, 'Production Process and Optimization of Solid Bioethanol from Empty Fruit Bunches of Palm Oil Using Response Surface Methodology', Processes, vol. 7, no. 10, pp. 715-715.
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This study aimed to observe the potential of solid bioethanol as an alternative fuel with high caloric value. The solid bioethanol was produced from liquid bioethanol, which was obtained from the synthesis of oil palm empty fruit bunches (PEFBs) through the delignification process by using organosolv pretreatment and enzymatic hydrolysis. Enzymatic hydrolysis was conducted using enzyme (60 FPUg−1 of cellulose) at a variety of temperatures (35 °C, 70 °C, and 90 °C) and reaction times (2, 6, 12, 18, and 24 h) in order to obtain a high sugar yield. The highest sugars were yielded at the temperature of 90 °C for 48 h (152.51 mg/L). Furthermore, fermentation was conducted using Saccharomyces cerevisiae. The bioethanol yield after fermentation was 62.29 mg/L. Bioethanol was extracted by distillation process to obtain solid bioethanol. The solid bioethanol was produced by using stearic acid as the additive. In order to get high-quality solid bioethanol, the calorific value was optimized using the response surface methodology (RSM) model. This model provided the factor variables of bioethanol concentration (vol %), stearic acid (g), and bioethanol (mL) with a minus result error. The highest calorific value was obtained with 7 g stearic acid and 5 mL bioethanol (43.17 MJ/kg). Burning time was tested to observe the quality of the solid bioethanol. The highest calorific value resulted in the longest burning time. The solid bioethanol has a potential as solid fuel due to the significantly higher calorific value compared to the liquid bioethanol.
Fang, J, Wu, C, Li, J, Liu, Q, Wu, C, Sun, G & Li, Q 2019, 'Phase field fracture in elasto-plastic solids: Variational formulation for multi-surface plasticity and effects of plastic yield surfaces and hardening', International Journal of Mechanical Sciences, vol. 156, pp. 382-396.
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© 2019 Elsevier Ltd The phase field modelling has been extended from brittle fracture to ductile fracture by incorporating plasticity. However, the effects of plastic yield functions and hardening on the fracture behaviour have not been examined systematically to date. The phase field fracture coupled with multi-surface plasticity is formulated in the variational framework for the unified yield criterion, which is able to facilitate the study on different yield surfaces. First, the homogeneous solutions of fracture in elasto-plastic solids are derived analytically for 1D and 2D cases. The results show that a greater hardening modulus would lead to an ascending branch of the stress versus strain curve; and the yield function may significantly affect the stress state and phase field damage. Second, the finite element (FE) technique is implemented for modelling the phase field fracture in elasto-plastic solids, in which the stress update and consistent tangent modular matrix are derived for the unified yield criterion. Finally, three numerical examples are presented to explore the effects of the yield function and material hardening. It is found that the yield function and material hardening could significantly affect the crack propagation and the final fracture pattern. In particular, the Tresca yield function tends to create a straight crack path orthogonal to the first principal stress, while the other yield functions show no sizeable difference in their crack paths.
Fang, J, Wu, C, Liu, Q, Sun, G & Li, Q 2019, 'Implicit Integration of the Unified Yield Criterion in the Principal Stress Space', Journal of Engineering Mechanics, vol. 145, no. 7, pp. 04019041-04019041.
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© 2019 American Society of Civil Engineers. An implicit numerical integration algorithm is presented for the unified yield criterion, which could encompass most other yield criteria. The modification matrix, which is used to convert the continuum tangent modular matrix into the consistent tangent modular matrix, is derived for the return to planes, lines, and the apex of the unified yield criterion with multisurface plasticity with discontinuities. The stress update and consistent tangent modular matrix are first derived in closed form in the principal stress space, and then they are transformed back into the general stress space by coordinate transformation. Three numerical examples are used to demonstrate the effectiveness of the presented algorithm. The correctness of the developed algorithm is validated by the analytical solution and ABAQUS solution with the built-in Mohr-Coulomb model. The developed algorithm is also demonstrated to be least twice more efficient than the ABAQUS built-in algorithm. The presented algorithm for the unified yield criterion can facilitate the understanding of the effect the intermediate principal stress. With the increase in b, the force versus deflection curve at the midspan increases for the beam under three-point bending, and the critical radius of the elastoplastic interface decreases (i.e., the plastic zone becomes small) for the circular tunnel under hydrostatic pressure.
Fang, J, Wu, C, Rabczuk, T, Wu, C, Ma, C, Sun, G & Li, Q 2019, 'Phase field fracture in elasto-plastic solids: Abaqus implementation and case studies', Theoretical and Applied Fracture Mechanics, vol. 103, pp. 102252-102252.
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© 2019 Elsevier Ltd Phase field modelling for fracture has been extended from elastic solids to elasto-plastic solids. In this study, we present the implementation procedures of a staggered scheme for phase field fracture of elasto-plastic solids in commercial finite element software Abaqus using subroutines UEL and UMAT. The UMAT is written for the constitutive behaviour of elasto-plastic solids, while the UEL is written for the phase field fracture. The phase field and displacement field are solved separately using the Newton-Raphson iteration method. In each iteration, one field is computed by freezing the other field at the last loading increment. A number of benchmark examples are tested from one single element up to 3D problems. The correctness of the staggered scheme is verified analytically in terms of the stress-strain curve and the evolution of the phase field in the one single element example. In the 2D and 3D problems, the fracture behaviour of elasto-plastic solids can be reproduced in terms of reaction force curve and crack propagation, which exhibit good agreement with the experimental observations and numerical results in literature. Not only can the proposed implementation help attract more academic researchers, but also engineering practitioners to take the advantages of phase field modelling for fracture in elasto-plastic solids. The Abaqus subroutine codes can be downloaded online from Mendeley data repository linked to this work (The link is provided in Supplementary material).
Fanos, AM & Pradhan, B 2019, 'A Novel Hybrid Machine Learning-Based Model for Rockfall Source Identification in Presence of Other Landslide Types Using LiDAR and GIS', Earth Systems and Environment, vol. 3, no. 3, pp. 491-506.
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© 2019, King Abdulaziz University and Springer Nature Switzerland AG. Abstract: Rockfall is a common phenomenon in mountainous and hilly areas worldwide, including Malaysia. Rockfall source identification is a challenging task in rockfall hazard assessment. The difficulty rise when the area of interest has other landslide types with nearly similar controlling factors. Therefore, this research presented and assessed a hybrid model for rockfall source identification based on the stacking ensemble model of random forest (RF), artificial neural network, Naive Bayes (NB), and logistic regression in addition to Gaussian mixture model (GMM) using high-resolution airborne laser scanning data (LiDAR). GMM was adopted to automatically compute the thresholds of slope angle for various landslide types. Chi square was utilised to rank and select the conditioning factors for each landslide type. The best fit ensemble model (RF–NB) was then used to produce probability maps, which were used to conduct rockfall source identification in combination with the reclassified slope raster based on the thresholds obtained by the GMM. Next, landslide potential area was structured to reduce the sensitivity and the noise of the model to the variations in different conditioning factors for improving its computation performance. The accuracy assessment of the developed model indicates that the model can efficiently identify probable rockfall sources with receiver operating characteristic curve accuracies of 0.945 and 0.923 on validation and training datasets, respectively. In general, the proposed hybrid model is an effective model for rockfall source identification in the presence of other landslide types with a reasonable generalisation performance. Graphic Abstract: [Figure not available: see fulltext.].
Fanos, AM & Pradhan, B 2019, 'A novel rockfall hazard assessment using laser scanning data and 3D modelling in GIS', CATENA, vol. 172, pp. 435-450.
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© 2018 Elsevier B.V. Rockfall hazards occur widely in regions with steep terrain such as Kinta Valley, Malaysia. Rockfalls threaten urban areas and the transportation corridors that pass through such areas. This paper proposes a comprehensive rockfall hazard assessment strategy based on high-resolution laser scanning data (LiDAR), both airborne and terrestrial. It provides (1) rockfall source identification by developing a hybrid model based on a bagging neural network (BBNN), which is compared with various machine learning algorithms and ensemble models (bagging, boosting, voting) and a Gaussian mixture model; (2) 3D modelling of rockfall kinematic processes (trajectory distribution, frequency, velocity, kinetic energy, bounce height, impact location); and (3) hazard zonation based on spatial modelling in combination with an analytical hierarchy process (AHP) in a geographic information system (GIS). In addition, mitigation measures are suggested based on the modelling results. The proposed methodology was validated in three study areas to test the applicability and generalisability of the methods. The results show that the proposed hybrid model can accurately identify rockfall source areas at the regional scale. It achieved a 97% training accuracy and 5-fold cross-validation area under curve (AUC) value of 0.96. The mechanical parameters of the developed 3D model were calibrated with an accuracy of 97%, 93% and 95% for Gunung Lang, Gua Tambun and Gunung Rapat areas, respectively. In addition, the proposed spatial model effectively delineates areas at risk of rockfalls. This method provides a comprehensive understanding of rockfall hazards that can assist authorities to develop proper management and protection of urban areas and transportation corridors.
Fanos, AM & Pradhan, B 2019, 'A Spatial Ensemble Model for Rockfall Source Identification From High Resolution LiDAR Data and GIS', IEEE Access, vol. 7, pp. 74570-74585.
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Fanos, AM, Pradhan, B, Mansor, S, Yusoff, ZM, Abdullah, AFB & Jung, HS 2019, 'Rockfall Source Identification Using a Hybrid Gaussian Mixture-Ensemble Machine Learning Model and LiDAR Data', Korean Journal of Remote Sensing, vol. 35, no. 1, pp. 93-115.
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The availability of high-resolution laser scanning data and advanced machine learning algorithms has enabled an accurate potential rockfall source identification. However, the presence of other mass movements, such as landslides within the same region of interest, poses additional challenges to this task. Thus, this research presents a method based on an integration of Gaussian mixture model (GMM) and ensemble artificial neural network (bagging ANN [BANN]) for automatic detection of potential rockfall sources at Kinta Valley area, Malaysia. The GMM was utilised to determine slope angle thresholds of various geomorphological units. Different algorithms (ANN, support vector machine [SVM] and k nearest neighbour [kNN]) were individually tested with various ensemble models (bagging, voting and boosting). Grid search method was adopted to optimise the hyperparameters of the investigated base models. The proposed model achieves excellent results with success and prediction accuracies at 95% and 94%, respectively. In addition, this technique has achieved excellent accuracies (ROC = 95%) over other methods used. Moreover, the proposed model has achieved the optimal prediction accuracies (92%) on the basis of testing data, thereby indicating that the model can be generalised and replicated in different regions, and the proposed method can be applied to various landslide studies.
Farzadkhoo, M, Keshavarzi, A, Hamidifar, H & Ball, J 2019, 'Flow and longitudinal dispersion in channel with partly rigid floodplain vegetation', Proceedings of the Institution of Civil Engineers - Water Management, vol. 172, no. 5, pp. 229-240.
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The influence of rigid vegetation on the longitudinal dispersion coefficient in a compound open channel was examined using an image processing technique. To simulate floodplain vegetation, cylinders of 5 mm diameter were attached to the floodplain surface. Potassium permanganate solution was used as a conservative tracer. Instantaneous velocity components were measured using particle image velocimetry. The results showed that, compared with non-vegetated conditions, floodplain vegetation decreased the depth-averaged longitudinal velocity and maximum tracer concentration by up to 83% and 12·5%, respectively. It was also found that the magnitude of the longitudinal dispersion coefficient, K, increased with the relative flow depth, Dr (the ratio of the floodplain to main channel flow depth). Furthermore, the value of K increased by up to 39·3% for vegetated tests compared with non-vegetated tests. Moreover, the results were compared with several previous empirical equations and the most appropriate equation for prediction of K in compound channels with partly vegetated floodplain was found to be that proposed by Fischer in 1975.
Fatahi, B 2019, 'Editorial', Proceedings of the Institution of Civil Engineers - Ground Improvement, vol. 172, no. 1, pp. 1-2.
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Fatimah, I, Sahroni, I, Fadillah, G, Musawwa, MM, Mahlia, TMI & Muraza, O 2019, 'Glycerol to Solketal for Fuel Additive: Recent Progress in Heterogeneous Catalysts', Energies, vol. 12, no. 15, pp. 2872-2872.
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Biodiesel has been successfully commercialized in numerous countries. Glycerol, as a byproduct in biodiesel production plant, has been explored recently for fuel additive production. One of the most prospective fuel additives is solketal, which is produced from glycerol and acetone via an acetalization reaction. This manuscript reviewed recent progress on heterogeneous catalysts used in the exploratory stage of glycerol conversion to solketal. The effects of acidity strength, hydrophobicity, confinement effect, and others are discussed to find the most critical parameters to design better catalysts for solketal production. Among the heterogeneous catalysts, resins, hierarchical zeolites, mesoporous silica materials, and clays have been explored as effective catalysts for acetalization of glycerol. Challenges with each popular catalytic material are elaborated. Future works on glycerol to solketal will be improved by considering the stability of the catalysts in the presence of water as a byproduct. The presence of water and salt in the feed is certainly destructive to the activity and the stability of the catalysts.
Fattah, IMR, Yip, HL, Jiang, Z, Yuen, ACY, Yang, W, Medwell, PR, Kook, S, Yeoh, GH & Chan, QN 2019, 'Effects of flame-plane wall impingement on diesel combustion and soot processes', Fuel, vol. 255, pp. 115726-115726.
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© 2019 Elsevier Ltd This work aims to assess the effects of flame-wall impingement on the combustion and soot processes of diesel flames. For this work, experimental measurements were performed in a constant-volume combustion chamber (CVCC) at ambient conditions that are representative of compression-ignition engines. The characteristics of impinging and free flames were compared at two identical ambient and injector conditions (20.8 kg/m3 ambient density, 6 MPa ambient pressure, 1000 K bulk temperature, 15 and 10 vol% ambient O2 concentration, and 100 MPa injection pressure). To simulate flame-wall impingement, a flat plane steel wall, normal to the injector axis, was initially placed at 53 mm from nozzle, but was varied from 53 to 35 mm during the experiments. Under the test conditions of this work, it was found that wall impingement resulted in lower soot temperature and soot content, in addition to a loss of momentum for the wall jet. The results also revealed that decreasing impingement distance from the nozzle resulted in reduced soot temperature and soot level for the wall jet. The reduced soot content observed for the wall jet appeared to be mainly driven by enhanced mixing. Flame transparency modeling was also performed to assess the uncertainties of two-color measurements for flame-plane wall impingement. The analysis indicated that the derived soot temperature and concentration values would be affected by the actual temperature profiles, rendering the technique useful to reveal trends, but not reliable for absolute soot concentration measurements.
Feng, J, Liu, L, Wu, D, Li, G, Beer, M & Gao, W 2019, 'Dynamic reliability analysis using the extended support vector regression (X-SVR)', Mechanical Systems and Signal Processing, vol. 126, pp. 368-391.
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© 2019 Elsevier Ltd For engineering applications, the dynamic system responses can be significantly affected by uncertainties in the system parameters including material and geometric properties as well as by uncertainties in the excitations. The reliability of dynamic systems is widely evaluated based on the first-passage theory. To improve the computational efficiency, surrogate models are widely used to approximate the relationship between the system inputs and outputs. In this paper, a new machine learning based metamodel, namely the extended support vector regression (X-SVR), is proposed for the reliability analysis of dynamic systems via utilizing the first-passage theory. Furthermore, the capability of X-SVR is enhanced by a new kernel function developed from the vectorized Gegenbauer polynomial, especially for solving complex engineering problems. Through the proposed approach, the relationship between the extremum of the dynamic responses and the input uncertain parameters is approximated by training the X-SVR model such that the probability of failure can be efficiently predicted without using other computational tools for numerical analysis, such as the finite element analysis (FEM). The feasibility and performance of the proposed surrogate model in dynamic reliability analysis is investigated by comparing it with the conventional ε-insensitive support vector regression (ε-SVR) with Gaussian kernel and Monte Carlo simulation (MSC). Four numerical examples are adopted to evidently demonstrate the practicability and efficiency of the proposed X-SVR method.
Feng, Y, Gao, W, Wu, D & Tin-Loi, F 2019, 'Machine learning aided stochastic elastoplastic analysis', Computer Methods in Applied Mechanics and Engineering, vol. 357, pp. 112576-112576.
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© 2019 Elsevier B.V. The stochastic elastoplastic analysis is investigated for structures under plane stress/strain conditions. A novel uncertain nonlinear analysis framework, namely the machine leaning aided stochastic elastoplastic analysis (MLA-SEPA), is presented herein via finite element method (FEM). The proposed MLA-SEPA is a favourable alternative to determine structural reliability when full-scale testing is not achievable, thus leading to significant eliminations of manpower and computational efforts spent in practical engineering applications. Within the MLA-SEPA framework, an extended support vector regression (X-SVR) approach is introduced and then incorporated for the subsequent uncertainty quantification. By successfully establishing the governing relationship between the uncertain system parameters and any concerned structural output, a comprehensive probabilistic profile including means, standard deviations, probability density functions (PDFs), and cumulative distribution functions (CDFs) of the structural output can be effectively established through a sampling scheme. Consequently, the nonlinear performance of the structure against both serviceability and strength limit states can be effectively investigated with the consideration of various system uncertainties. Three numerical examples are thoroughly investigated to illustrate the accuracy, applicability and effectiveness of the proposed MLA-SEPA approach.
Feng, Y, Zhao, Y, Jiang, B, Zhao, H, Wang, Q & Liu, S 2019, 'Discrepant gene functional potential and cross-feedings of anammox bacteria Ca. Jettenia caeni and Ca. Brocadia sinica in response to acetate', Water Research, vol. 165, pp. 114974-114974.
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© 2019 Elsevier Ltd Although the enhancement of anammox performance for wastewater treatment due to the addition of small amount of acetate has been reported, discrepant metabolic responses of different anammox species have not been experimentally evaluated. Based on metagenomics and metatranscriptomic data, we investigated the competitiveness between two typical anammox species, Candidatus Jettenia caeni (J. caeni) and Candidatus Brocadia sinica (B. sinica), in anammox consortia under mixotrophic condition, where complex metabolic interactions among anammox bacteria and heterotrophs also changed with acetate addition. Contrary to J. caeni, the dissimilatory nitrate reduction to ammonium pathway of B. sinica was markedly stimulated for improving nitrogen removal. More acetate metabolic pathways and up-regulated AMP-acs expression for acetyl-CoA synthesis in B. sinica contributed to its superiority in acetate utilization. Interestingly, cross-feedings, including the nitrogen cycle, amino acid cross-feeding and B-vitamin metabolic exchange between B. sinica and other heterotrophs seemed to be enhanced with acetate addition, contributing to a reduction in metabolic energy cost to the whole community. Our work not only clarified the mechanism underlying discrepant responses of different anammox species to acetate, but also suggests a possible strategy for obtaining higher nitrogen removal rates in wastewater treatment under low C/N ratio.
Fu, J, Liu, Q, Liufu, K, Deng, Y, Fang, J & Li, Q 2019, 'Design of bionic-bamboo thin-walled structures for energy absorption', Thin-Walled Structures, vol. 135, pp. 400-413.
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© 2018 Elsevier Ltd Bio-inspired engineering design has drawn considerable attention in the recent years for its great structural and mechanical features. This study aimed to explore the energy absorption characteristics of a novel bionic-bamboo tube (BBT) structure subjected to axial crushing. The tubes with six different cross-sectional configurations were devised with inspiration of bamboo microstructure. The effects of rib shape and rib number were analyzed by using the finite element code LS-DYNA. The numerical results indicated that the BBT structures with the rib shape of “X” and the rib number of six exhibited the best crashworthiness. To further improve the energy absorption capabilities of these BBT structures, the multiobjective optimization was employed with respect to design variables of configurational structure, such as the rib angle of the “X” shaped cross-section, center distance and rib thickness. The response surface method (RSM) and multiobjective particle swarm optimization (MOPSO) algorithm were adopted to maximize specific energy absorption (SEA) while minimizing peak crushing force (PCF). The optimization results demonstrated that compared to the baseline design, the SEA value of the optimized BBT structure was further increased by 6.84% without sacrificing in peak crushing force.
Gan, YY, Ong, HC, Ling, TC, Chen, W-H & Chong, CT 2019, 'Torrefaction of de-oiled Jatropha seed kernel biomass for solid fuel production', Energy, vol. 170, pp. 367-374.
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Gao, H, Liu, Z, Yang, Y, Wu, C & Geng, J 2019, 'Blast-resistant performance of aluminum foam-protected reinforced concrete slabs', Baozha Yu Chongji/Explosion and Shock Waves, vol. 39, no. 2.
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n order to study the blast-resistant protective effect of the aluminum foam slab as porous energy absorbing material on the engineering structure, using an outdoor explosion test, the dynamic response and failure modes of reinforced concrete (RC) slabs with different aluminum foam protective layers under blast loading were studied, and the finite element model was established by using the LS-DYNA software. Through comparison with the test, the feasibility of the model was verified. The dynamic responses of RC slabs with or without aluminum foam protective layers were compared and analyzed, and the effects of aluminum foam density gradient distribution and longitudinal reinforcement ratio were analyzed. The results show that the finite element model can accurately describe the dynamic response of RC slabs with aluminum foam protective layers. Aluminum foam protective layers can effectively reduce the deflection of reinforced concrete slabs and reduce the damage of specimens. The aluminum foam density increases from bottom to top, which has the best blast-resistant performance on RC slabs. Moreover, increasing the reinforcement ratio can improve the blast-resistant performance of aluminum foam-protected RC slabs.
Gao, P, Wang, X, Huang, Z & Yu, H 2019, '11B NMR Chemical Shift Predictions via Density Functional Theory and Gauge-Including Atomic Orbital Approach: Applications to Structural Elucidations of Boron-Containing Molecules', ACS Omega, vol. 4, no. 7, pp. 12385-12392.
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© 2019 American Chemical Society. 11B nuclear magnetic resonance (NMR) spectroscopy is a useful tool for studies of boron-containing compounds in terms of structural analysis and reaction kinetics monitoring. A computational protocol, which is aimed at an accurate prediction of 11B NMR chemical shifts via linear regression, was proposed based on the density functional theory and the gauge-including atomic orbital approach. Similar to the procedure used for carbon, hydrogen, and nitrogen chemical shift predictions, a database of boron-containing molecules was first compiled. Scaling factors for the linear regression between calculated isotropic shielding constants and experimental chemical shifts were then fitted using eight different levels of theory with both the solvation model based on density and conductor-like polarizable continuum model solvent models. The best method with the two solvent models yields a root-mean-square deviation of about 3.40 and 3.37 ppm, respectively. To explore the capabilities and potential limitations of the developed protocols, classical boron-hydrogen compounds and molecules with representative boron bonding environments were chosen as test cases, and the consistency between experimental values and theoretical predictions was demonstrated.
Gao, Y, Xu, Y, Wu, C & Fang, J 2019, 'Topology Optimization of Metal and Carbon Fiber Reinforced Plastic (CFRP) Structures under Loading Uncertainties', SAE Technical Paper Series, vol. 2019-April, no. April.
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© 2019 SAE International. All Rights Reserved. Carbon fiber reinforced plastic (CFRP) composite materials have gained particular interests due to their high specific modulus, high strength, lightweight and perfect corrosion resistance. However, in reality, CFRP composite materials cannot be used alone in some critical places such as positions of joints with hinges, locks. Therefore, metal reinforcements are usually necessary in local positions to prevent structure damage. Besides, if uncertainties present, obtained optimal structures may experience in failures as the optimization usually pushes solutions to the boundaries of constraints and has no room for tolerance and uncertainties, so robust optimization should be considered to accommodate the uncertainties in practice. This paper proposes a mixed topology method to optimize metal and carbon fiber reinforced plastic composite materials simultaneously under nondeterministic load with random magnitude and direction. A joint cost function is employed to contain both the mean and standard deviations of compliance in the robust optimization. The sensitivities of the cost function are derived with respect to the design variables in a nondeterministic context. The discrete material and thickness optimization (DMTO) technique is applied to undertake robust topology optimization for CFRP composites and metal material while the casting constraint to prevent intermediate void was introduced. In this study, two examples are presented to demonstrate the effectiveness of the proposed methods. The robust topology optimization results exhibit that the composite structures with proper distribution of materials and orientations are of more stable performance when the load fluctuates.
Ghasemi, M, Rasekh, H, Berenjian, J & AzariJafari, H 2019, 'Dealing with workability loss challenge in SCC mixtures incorporating natural pozzolans: A study of natural zeolite and pumice', Construction and Building Materials, vol. 222, pp. 424-436.
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Ghodousi, Alesheikh, Saeidian, Pradhan & Lee 2019, 'Evaluating Citizen Satisfaction and Prioritizing Their Needs Based on Citizens’ Complaint Data', Sustainability, vol. 11, no. 17, pp. 4595-4595.
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Citizen Relationship Management (CiRM) is one of the important matters in citizen-centric e-government. In fact, the most important purpose of e-government is to satisfy citizens. The ‘137 system’ is one of the most important ones based on the citizen-centric that is a municipality phone based request/response system. The aim of this research is a data-mining of a ‘137 system’ (citizens’ complaint system) of the first district of Bojnourd municipality in Iran, to prioritize the urban needs and to estimate citizens’ satisfaction. To reach this, the K-means and Bees Algorithms (BA) were used. Each of these two algorithms was executed using two different methods. In the first method, prioritization and estimation of satisfaction were done separately, whereas in the second method, prioritization and estimation of satisfaction were done simultaneously. To compare the clustering results in the two methods, an index was presented quantitatively. The results showed the superiority of the second method. The index of the second method for the first needs in K-means was 0.299 more than the first method and it was the same in two methods in BA. Also, the results of the BA clustering were better at it because of the S (silhouette) and CH (Calinski-Harabasz) indexes. Considering the final prioritization done by the two algorithms in two methods, the primary needs included asphalt, so specific schemes should be considered.
Giri, P, Kharkovsky, S, Zhu, X, Clark, SM & Samali, B 2019, 'Debonding detection in a carbon fibre reinforced concrete structure using guided waves', Smart Materials and Structures, vol. 28, no. 4, pp. 045020-045020.
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© 2019 IOP Publishing Ltd. Guided waves are traditionally used in different non-destructive testing applications because of their cost-effectiveness and piezoelectric patches that are easy to incorporate into the structure as transducers. The non-destructive evaluation of interfacial defects such as debonding in a composite structure is critical for safety and long-term use. A new guided wave technique to detect a variety of debondings in carbon fibre reinforced concrete structure has been developed and experimental testing has been carried out to verify the proposed approach. Five composite specimens with different debondings have been prepared. The received guided wave in the specimen with a perfect bonding is taken as a reference. This signal is compared with the received signal under different debonding conditions. The debonding is quantified using three damage indices: correlation coefficient, change in peak-to-peak and root mean square deviation. The results demonstrated that these indices could be a good indicator of the debond conditions as they correlated linearly with the extent of the debonding. The proposed method is effective in detecting interfacial defects in an existing structure without special preparation.
Giri, P, Kharkovsky, S, Zhu, X, Clark, SM, Taheri, S & Samali, B 2019, 'Characterization of carbon fiber reinforced polymer strengthened concrete and gap detection with a piezoelectric-based sensory technique', Structural Health Monitoring, vol. 18, no. 1, pp. 172-179.
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In this article, a piezoelectric-based sensory technique is proposed for detection of the gap between surfaces of a carbon fiber reinforced polymer plate and a concrete specimen and characterization of shrinkage of early-age concrete. The proposed technique uses the propagation properties of the guided waves in the carbon fiber reinforced polymer plate excited and received by piezoelectric transducers attached to an external surface of the carbon fiber reinforced polymer–strengthened concrete specimen. Measurements are conducted with fresh and hardened early-age concrete specimens and two carbon fiber reinforced polymer plates at different gaps. A piezoelectric actuator is excited using a sine burst signal, and the generated wave is received by a sensor after propagation along the specimen. The received signal at different gap values is used to detect a gap. To quantify the gap, damage indices, including correlation coefficient, peak-to-peak amplitude of resultant signal, and root-mean-square deviation, are used. The shrinkage of concrete is detected and predicted by comparing the damage indices at different gaps with the indices at different stages of early-age concrete. The proposed technique is relatively simple method using small transducers. It is one-sided, non-destructive, and cost-effective solution for gap detection and concrete characterization.
Goh, BHH, Ong, HC, Cheah, MY, Chen, W-H, Yu, KL & Mahlia, TMI 2019, 'Sustainability of direct biodiesel synthesis from microalgae biomass: A critical review', Renewable and Sustainable Energy Reviews, vol. 107, pp. 59-74.
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© 2019 Elsevier Ltd Microalgae has been identified as a potential feedstock for biodiesel production since its cultivation requires less cropland compared to conventional oil crops and the high growth rate of microalgae. Research on microalgae oils often are focused on microalgae oil extraction and biomass harvesting techniques. However, energy intensive and costly lipid extraction methods are the major obstacles hampering microalgae biodiesel commercialisation. Direct biodiesel synthesis avoids such problems as it combines lipid extraction techniques and transesterification into a single step. In this review, the potential of direct biodiesel synthesis from microalgae biomass was comprehensively analysed. The various species of microalgae commonly used as biodiesel feedstock was critically assessed, particularly on high lipid content species. The production of microalgae biodiesel via direct conversion from biomass was systematically discussed, covering major enhancements such as heterogeneous catalysts, the use of ultrasonic and microwave- techniques and supercritical alcohols that focus on the overall improvement of biodiesel production. In addition, this review illustrates the cultivation conditions for biomass growth and lipid productivity improvement, the available harvesting and lipid extraction technologies, as well as the key challenges and future prospect of microalgae biodiesel production. This review serves as a basis for future research on direct biodiesel synthesis from modified microalgae biomass to improve profitability of microalgae biodiesel.
Golhani, K, Balasundram, SK, Vadamalai, G & Pradhan, B 2019, 'Estimating chlorophyll content at leaf scale in viroid-inoculated oil palm seedlings (Elaeis guineensis Jacq.) using reflectance spectra (400 nm–1050 nm)', International Journal of Remote Sensing, vol. 40, no. 19, pp. 7647-7662.
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Golhani, K, Balasundram, SK, Vadamalai, G & Pradhan, B 2019, 'Selection of a Spectral Index for Detection of Orange Spotting Disease in Oil Palm (Elaeis guineensis Jacq.) Using Red Edge and Neural Network Techniques', Journal of the Indian Society of Remote Sensing, vol. 47, no. 4, pp. 639-646.
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© 2019, Indian Society of Remote Sensing. Spectral screening can play an important role in successful detection of viroid-infected oil palm seedlings from nursery stage prior to transplanting into the field. Coconut cadang–cadang viroid (CCCVd) is the main causal agent of orange spotting (OS) disease. OS disease is an emerging disease in Malaysian plantation. In this study, a glasshouse experiment was conducted with fifteen CCCVd-inoculated and five healthy oil palm seedlings in the growing season of 2015. Spectral screening was performed using a hyperspectral spectroradiometer, Analytic Spectral Device HandHeld 2 (325–1075 nm). The red edge, a steep gradient in reflectance between red and near-infrared bands (680–780 nm), was used for selection of red edge bands. A maximum point (i.e., 700 nm) and minimum point (i.e., 768 nm) of red edge were selected from healthy and inoculated spectra. Shifts of red edge inflection point from healthy to inoculated spectra were also studied. Four well-known spectral indices, namely simple ratio, red edge normalized difference vegetation index, two-band enhanced vegetation index 2 (EVI2), and chlorophyll index red edge, were evaluated using selected red edge bands. The multilayer perceptron neural network model was used to establish a nonlinear relationship between selected spectral bands and each spectral index. EVI2 was selected as a best spectral index which resulted in zero errors at the training, testing, and validation datasets. The highest coefficient of correlation (r = 1) was recorded between spectral bands (input values) and EVI2 (target values).
Gonzales, RR, Park, MJ, Bae, T-H, Yang, Y, Abdel-Wahab, A, Phuntsho, S & Shon, HK 2019, 'Melamine-based covalent organic framework-incorporated thin film nanocomposite membrane for enhanced osmotic power generation', Desalination, vol. 459, pp. 10-19.
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© 2019 A melamine-based covalent organic framework (COF) nanomaterial, Schiff base network-1 (SNW-1), was incorporated into the polyamide layer of a novel thin film nanocomposite (TFN) pressure retarded osmosis (PRO) membrane. The deposition of SNW-1 was made on an open mesh fabric-reinforced polyamide-imide (PAI) support substrate through interfacial polymerization (IP). SNW-1 loading influence on the water permeability and osmotic power density during PRO operation was investigated. The porous and highly hydrophilic SNW-1 nanomaterial facilitated the flow of water molecules across the membranes, while maintaining satisfactory salt rejection ability of the polyamide selective layer. The membranes exhibited significantly enhanced surface hydrophilicity, water permeability, and power density. The mode of incorporation of SNW-1 during IP was also investigated and it was observed that the secondary amine groups of SNW-1 react with the carbonyl groups of 1,3,5-benzenetricarbonyl trichloride, the acyl halide precursor in polyamide formation; thus, SNW-1 was incorporated through the amine precursor, 1,3-phenylenediamine. Testing with 1.0 M NaCl as the draw solution, the TFN membrane with a loading of 0.02 wt% SNW-1 exhibited the highest water flux of 42.5 Lm−2 h−1 and power density of 12.1 Wm−2, while withstanding hydraulic pressure over 24 bar. This study suggests that COF-incorporation can be a promising method in PRO membrane fabrication to improve both osmotic performance and energy harvesting capability for the PRO process.
Gowripalan, N, Nguyen, T, Yang, Y, Li, J & Sirivivatnanon, V 2019, 'Evaluation of elastic modulus reduction due to ASR', Concrete in Australia, vol. 45, no. 2, pp. 47-52.
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Evaluation of reduction in modulus of elasticity of concrete undergoing alkali silica reaction is carried out using an artificial neural network
Grant, M & Stewart, MG 2019, 'Postal IEDs and risk assessment of work health and safety considerations for postal workers', International Journal of Risk Assessment and Management, vol. 22, no. 2, pp. 152-152.
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Postal improvised explosive devices (IEDs) provide criminals and terrorists with a convenient mechanism for delivering an energetic payload to an intended victim with little operational risk. Postal IEDs formed 7% of IED attacks reported in the West between 1998-2015, are often dispatched in groups and can bring postal systems to a standstill. Nearly 30% of postal IED explosions occur in the postal worker environment and a third of the casualties caused by postal IEDs are postal workers. Postal IEDs are debatably a reasonably foreseeable cause of harm to postal workers and should be considered under the work health and safety (WHS) constructs of many Western nations. This paper considers this problem, using a probabilistic risk assessment model to inform a cost-benefit analysis considering potential risk reduction options for postal workers. It identifies that the control measures identified were not cost-effective where only the direct WHS costs pertaining to unintentional postal IED detonation within the mail delivery system were considered given the risk levels identified.
Gravina da Rocha, C, El Ghoz, HBC & Jr Guadanhim, S 2019, 'A model for implementing product modularity in buildings design', Engineering, Construction and Architectural Management, vol. 27, no. 3, pp. 680-699.
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PurposeThe purpose of this paper is to examine the fundamental underpinnings of product modularity and how these can be adapted to construction and its specificities (e.g. one-off products delivered by temporary supply chains) to create a model to design modular buildings.Design/methodology/approachThis research adopts a design science research approach. Explanation I (substantive theory devising based on the analysis of an artefact ‒ a low-income housing project) is used, followed by Solution Incubation (a model to implement product modularity in buildings design).FindingsThe model allows product modularity to be implemented at distinct levels (i.e. building, systems and components) at a single stage (building design), different from manufacturing where each level is considered at a distinct stage. This is in line with the project investigated: modularity was considered for house layouts, roof types and gable formats.Practical implicationsThe model provides a hands-on tool for practitioners to design modular buildings. The low-income project is also extensively detailed: three-dimensional models, floor plans and conceptual diagrams (outlining how fundamental underpinnings were applied at each level) are presented. There is a lack of comprehensive accounts such as the one presented here to demonstrate the application of product modularity in real-world projects.Originality/valueThis paper identifies and adapts the fundamental underpinnings of product modularity to constructi...
Gu, X, Yu, Y, Li, Y, Li, J, Askari, M & Samali, B 2019, 'Experimental study of semi-active magnetorheological elastomer base isolation system using optimal neuro fuzzy logic control', Mechanical Systems and Signal Processing, vol. 119, pp. 380-398.
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© 2018 Elsevier Ltd In this paper, a “smart” base isolation strategy is proposed in this study utilising a semi-active magnetorheological elastomer (MRE) isolator whose stiffness can be controlled in real-time and reversible fashion. By modulating the applied current, the horizontal stiffness of the MRE isolator can be controlled and thus the control action can be generated for the isolated structure. To overcome the inherent nonlinearity and hysteresis of the MRE isolator, radial basis function neural network based fuzzy logic control (RBF-NFLC) was developed due to its inherent robustness and capability in coping with uncertainties. The NFLC was optimised by a non-dominated sorting genetic algorithm type II (NSGA-II) for better suited fuzzy control rules as well as most appropriate parameters for the membership functions. To evaluate the effectiveness of the proposed smart base isolation system, four scenarios are tested under various historical earthquake excitations, i.e. bare building with no isolation, passive isolated structure, MRE isolated structure with Bang-Bang control, MRE isolated structure with proposed NFLC. A three-storey shear building model was adopted as the testing bed. Through the testing results, limited performance of passive isolation system was revealed. In contrast, the adaptability of the proposed isolation strategy was demonstrated and it is proven that the smart MRE base isolation system is able to provide satisfactory protection for both structural and non-structural elements of the system over a wide range of hazard dynamic loadings.
Guo, G, Sun, Y, Fu, Q, Ma, Y, Zhou, Y, Xiong, Z & Liu, Y 2019, 'Sol-gel synthesis of ternary conducting polymer hydrogel for application in all-solid-state flexible supercapacitor', International Journal of Hydrogen Energy, vol. 44, no. 12, pp. 6103-6115.
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© 2019 Hydrogen Energy Publications LLC In this contribution, we reported the preparation of a novel conducting polymer hydrogel (CPH) by a sol-gel method, which was subsequently employed to fabricate a flexible all-solid-state supercapacitor device. Taking advantage of the synergistic effects of the different components in the conducting polymer hydrogel and the merits of the proposed synthesis strategies, the prepared supercapacitor device with CPH as electrode exhibited high area-normalized capacitance (2.2 F cm −2 ), high gravimetric capacitance (1573.6 F g −1 ) as well as high energy density of 0.18 mWh cm −2 (or 128.7 Wh Kg −1 ) at 0.08 mW cm −2 (or 55.1 W kg −1 ). This study did not only represent a novel all-solid-state, high performance, flexible supercapacitor with potential applications in flexible energy-related devices, but also developed a new method for enhancing capacitances and mechanical stability of all-solid-state flexible supercapacitor.
Guo, H, Hu, J, Li, J, Gao, M-T, Wang, Q, Guo, W & Ngo, HH 2019, 'Systematic insight into the short-term and long-term effects of magnetic microparticles and nanoparticles on critical flux in membrane bioreactors', Journal of Membrane Science, vol. 582, pp. 284-288.
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© 2019 This study aims to systematically investigate the short-term and long-term effects of magnetic microparticles (MPs) and nanoparticles (NPs) on critical flux in membrane bioreactors (MBRs). Comparison among six MBRs was carried out with different activated sludge samples. Results showed that the short-term adsorption and flocculation contributed only minimally, however, the long-term magnetic induced bio-effect improved the critical flux by conditioning sludge properties. Additional molecular weight distribution of soluble microbial product (SMP) indicated that long-term magnetic induced bio-effect declined the content of macromolecules (>500 kDa and 300–500 kDa), but promoted the content of small molecules (<100 kDa), consequently reduced the free energy of SMP gelling foulants, and further promoted the higher critical flux. Moreover, the magnetic MPs presented the better performance than NPs. This study illustrated that sufficient pre-acclimatization of magnetic activated sludge is significantly necessary to improve the critical flux in MBRs.
Guo, W, Lei, Z, Wang, J & Wei, D 2019, 'Special issue on challenges in biological wastewater treatment and resource recovery', Bioresource Technology Reports, vol. 7, pp. 100243-100243.
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Habib, M, Alfugara, A & Pradhan, B 2019, 'A LOW-COST SPATIAL TOOL FOR TRANSFORMING FEATURE POSITIONS OF CAD-BASED TOPOGRAPHIC MAPPING', Geodesy and cartography, vol. 45, no. 4, pp. 161-168.
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In fact, Computer Aided Design (CAD) offers powerful design tools to produce digital large scale topographic mapping that is considered the backbone for construction projects, urban planning and landscape architecture. Nowadays local agencies in small communities and developing countries are facing some difficulties in map to map transformation and handling discrepancies between the physical reality and represented spatial data due to the need for implementing high cost systems such as GIS and the experienced staff required. Therefore, the require for providing a low-cost tool based on the most common CAD system is very important to guarantee a quality and positional accuracy of features. The main aim of this study is to describe a mathematical relationship to fulfil the coordinate conversion between two different grid references applying two-dimensional conformal polynomial models built on control points and a least squares fitting algorithm. In addition, the automation of this model was performed in the Microsoft Visual Studio environment to calculate polynomial coefficients and convert the positional property of entities in AutoCAD by developing spatial CAD tool. To evaluate the proposed approach the extracted coordinates of check points from the interpolation surface are compared with the known ones.
Hafiz, MA, Hawari, AH & Altaee, A 2019, 'A hybrid forward osmosis/reverse osmosis process for the supply of fertilizing solution from treated wastewater', Journal of Water Process Engineering, vol. 32, pp. 100975-100975.
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© 2019 Elsevier Ltd This work investigates the application of a hybrid system that combines forward osmosis (FO) and reverse osmosis (RO) processes for the supply of a fertilizing solution that could be used directly for irrigation purposes. In the FO process the feed solution is treated sewage effluent (TSE) and two different types of draw solutions were investigated. The impact of the feed solution and the draw solution flowrates and the membrane orientation on the membrane flux were investigated in the forward osmosis process. RO was used for the regeneration of the draw solution. In the forward osmosis process it was found that the highest membrane flux was 13.2 LMH. The FO process had high rejection rates for total phosphorus and ammonium which were 99% and 97%, respectively. RO achieved 99% total salts rejection rate. Seawater RO (SW30HR) and brackish water RO (BW30LE) membranes were used for the regeneration of the draw solution. The specific power consumption for the regeneration of the draw solution was 2.58 kW h/m3 and 2.18 kW h/m3 for SW30HR and BW30LE membranes, respectively. The final product water had high quality in terms of total dissolved solids concentration but the concentration of phosphorus was slightly higher than recommended due to adding 0.1 M of diammonium phosphate in the draw solution.
Hakdaoui, S, Emran, A, Pradhan, B, Lee, C-W & Nguemhe Fils, SC 2019, 'A Collaborative Change Detection Approach on Multi-Sensor Spatial Imagery for Desert Wetland Monitoring after a Flash Flood in Southern Morocco', Remote Sensing, vol. 11, no. 9, pp. 1042-1042.
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This study aims to present a technique that combines multi-sensor spatial data to monitor wetland areas after a flash-flood event in a Saharan arid region. To extract the most efficient information, seven satellite images (radar and optical) taken before and after the event were used. To achieve the objectives, this study used Sentinel-1 data to discriminate water body and soil roughness, and optical data to monitor the soil moisture after the event. The proposed method combines two approaches: one based on spectral processing, and the other based on categorical processing. The first step was to extract four spectral indices and utilize change vector analysis on multispectral diachronic images from three MSI Sentinel-2 images and two Landsat-8 OLI images acquired before and after the event. The second step was performed using pattern classification techniques, namely, linear classifiers based on support vector machines (SVM) with Gaussian kernels. The results of these two approaches were fused to generate a collaborative wetland change map. The application of co-registration and supervised classification based on textural and intensity information from Radar Sentinel-1 images taken before and after the event completes this work. The results obtained demonstrate the importance of the complementarity of multi-sensor images and a multi-approach methodology to better monitor changes to a wetland area after a flash-flood disaster.
Han, R, Khan, MH, Angeloski, A, Casillas, G, Yoon, CW, Sun, X & Huang, Z 2019, 'Hexagonal Boron Nitride Nanosheets Grown via Chemical Vapor Deposition for Silver Protection', ACS Applied Nano Materials, vol. 2, no. 5, pp. 2830-2835.
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© 2019 American Chemical Society. In this study, hexagonal boron nitride nanosheets (h-BNNS) have been grown on polycrystalline silver substrates via chemical vapor deposition (CVD) using ammonia borane as a precursor. The h-BNNS are of few-atomic-layer thickness and form continuous coverage over the whole Ag substrate. The atomically thin coating poses negligible interference to the reflectivity in the UV-visible range. The nanosheet coating also proves very effective in protecting Ag foil chemically. In contrast to bare Ag foil, the coated foil displayed only minor decolorization under high concentration of H2S. The study indicates that h-BNNS can be a promising protective coating for Ag based items such as jewelry or mirrors used in astronomical telescopes.
Han, S-F, Jin, W, Abomohra, AE-F, Zhou, X, Tu, R, Chen, C, Chen, H, Gao, S-H & Wang, Q 2019, 'Enhancement of Lipid Production of Scenedesmus obliquus Cultivated in Municipal Wastewater by Plant Growth Regulator Treatment', Waste and Biomass Valorization, vol. 10, no. 9, pp. 2479-2485.
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© 2018, Springer Science+Business Media B.V., part of Springer Nature. Effects of four different plant growth regulators including indole-3-acetic acid (IAA), 1-triacontanol (TRIA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (6-BA) on biomass and lipid productivity of microalga Scenedesmus obliquus cultured in municipal wastewater were primarily studied. The results showed that the lipid productivity of S. obliquus was significantly increased by 30.5 and 23.6% after the treatment by IAA and TRIA, respectively. According to the GC analysis of the lipids, the addition of IAA and TRIA could increase the content of monounsaturated fatty acid in S. obliquus, and thus improving the grade of biodiesel. After the addition of IAA and TRIA, the nitrogen content of S. obliquus significantly decreased, while bacterial diversity in wastewater increased, which could enhance the stability of microbial system in the wastewater medium. Meanwhile, significant increase were also found in the abundances of β-Proteobacteria and α-Proteobacteria.
Han, S-F, Jin, W, Yang, Q, El-Fatah Abomohra, A, Zhou, X, Tu, R, Chen, C, Xie, G-J & Wang, Q 2019, 'Application of pulse electric field pretreatment for enhancing lipid extraction from Chlorella pyrenoidosa grown in wastewater', Renewable Energy, vol. 133, pp. 233-239.
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© 2018 Elsevier Ltd Lipid extraction is a key step of biodiesel production from microalgae, however, the application of traditional extraction methods was limited due to the difficulties of cell disruption as well as solvent toxicity. In this work, pretreatment method using pulsed electric field (PEF), was primarily applied to lipid extraction process from microalgae Chlorella pyrenoidosa grown in wastewater. After the pretreatment with PEF, the yields of fatty acid methyl esters from C.pyrenoidosa was 12.0% higher than traditional pretreatment with ultrasonic. The results indicated that PEF was an effective method for cell disruption. Fluorescence staining and scanning electron microscopy showed that the integrity of the cell membrane of microalgae was damaged under pulsed electric field, which enhanced the penetration of solvents and lipid extraction.
Hao, Q, Liu, Y, Chen, T, Guo, Q, Wei, W & Ni, B-J 2019, 'Bi2O3@Carbon Nanocomposites for Solar-Driven Photocatalytic Degradation of Chlorophenols', ACS Applied Nano Materials, vol. 2, no. 4, pp. 2308-2316.
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Copyright © 2019 American Chemical Society. Chlorophenols are corrosive and toxic in a water environment, which have caused increasing concerns and encourage the development of solar-driven techniques with highly efficient photocatalysts for green remediation. Coupling photocatalysis with the surface plasmon resonance (SPR) effect is a practical solution for boosting the utilization of solar light in the IR region while improving the overall performance of the photocatalysts. However, a facile and green strategy to synthesize metallic non-noble bismuth (Bi0)-based photocatalysts is still lacking. Herein, we report smart Bi/Bi2O3/C composites with high performance for the photocatalytic degradation of 2,4-dichlorophenol. Advanced characterizations such as X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy are applied to analyze the morphology and structure of the prepared materials. The photodegradation rate of the hybrid is significantly enhanced compared with the sole counterparts, which are 1.60-fold of Bi2O3 and 2.47-fold of g-C3N4. The synthesized Bi/C-2 exhibits excellent stability without a decline in activity after four cycles. The SPR effect of Bi is identified to account for the strengthened photoreactivity. Moreover, the relatively high utilization efficiency of solar energy and the rapid separation rate of photogenerated electron and hole pairs helped to enhance the photocatalytic performance synergistically. ©
Hassoun, M & Fatahi, B 2019, 'Novel integrated ground anchor technology for the seismic protection of isolated segmented cantilever bridges', Soil Dynamics and Earthquake Engineering, vol. 125, pp. 105709-105709.
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© 2019 Elsevier Ltd An external restraining system which is anchoring the bridge superstructure to the embankment backfill is proposed in this study for the seismic protection of isolated bridges. The restraining system is employed to reduce the seismic demands of the bridge deck by utilising the otherwise inactive ground behind the abutment back-walls. The system can be described as fastening the bridge end-diaphragms to the rocky strata that lie beneath the abutment backfill. The anchoring is achieved through a series of steel strands grouted to the rock to achieve a strong anchoring capacity. Indeed, the proposed anchor is flexible enough to allow the thermal, creep and shrinkage serviceability movements of the deck. A parametric study conducted in this paper shows that the ground anchor external restraining system is truly effective in reducing the seismic demands of the bridge deck.
He, L-X, Wu, C & Li, J 2019, 'Post-earthquake evaluation of damage and residual performance of UHPSFRC piers based on nonlinear model updating', Journal of Sound and Vibration, vol. 448, pp. 53-72.
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© 2019 Elsevier Ltd This paper presents an innovative approach for damage and residual performance evaluation of ultra-high performance steel fiber reinforced concrete (UHPSFRC) piers after earthquakes utilizing low-level vibration tests. A nonlinear fiber section element model is constructed in OpenSees to simulate the hysteretic behavior of a UHPSFRC bridge pier. Experimental data from a UHPSFRC column is utilized to verify the accuracy of the nonlinear numerical model. Based on the nonlinear fiber section element model, a new technique of nonlinear finite element model updating involving two updating stages is developed. This new method is designed to incorporate the maximum and minimum strains of section fibers as the updating parameters. By forming the objective function from the modal information, the damage parameters related to the nonlinear material model can be updated by solving the constrained optimization problem. To validate the efficiency of this updating approach, it has been applied to a numerically simulated UHPSFRC pier. With using the updated nonlinear finite element model, the residual axial loading capacity and post-seismic performance of the UHPSFRC pier are examined. The numerical results indicate that the updated nonlinear finite element model can be used not only to assess the current damage state of the UHPSFRC pier but also to predict its future performance after an earthquake. Finally, the noise effect on the proposed method is also investigated. The results reveal that the post-earthquake evaluation approach for UHPSFRC piers based on this study's updating algorithm is robust to noise.
He, X, Wu, W & Wang, S 2019, 'A constitutive model for granular materials with evolving contact structure and contact forces—Part I: framework', Granular Matter, vol. 21, no. 2.
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He, X, Wu, W & Wang, S 2019, 'A constitutive model for granular materials with evolving contact structure and contact forces—part II: constitutive equations', Granular Matter, vol. 21, no. 2.
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© 2019, The Author(s). This and the companion paper present a constitutive model for granular materials with evolving contact structure and contact forces, where the contact structure and contact forces are characterised by some statistics of grain-scale entities such as contact normals and contact forces. And these statistics are actually the “fabric” or “force” terms in the “stress–force–fabric” (SFF) equation. The stress–strain response is obtained by inserting the predicted “fabric” or “force” terms from evolution equations into the SFF equation. In the model, the critical state is characterised by two fitting equations and three critical state parameters. A semi-mechanistic analysis is conducted about the change of the contact number and the obtained results are combined with observed phenomena in DEM virtual experiments to give the constitutive equations for the “fabric” terms. The change of fabric anisotropy is related to the strain rate, current fabric anisotropy and also contact forces. The change of coordination number is induced by two terms related to volumetric and shear deformations, and also an additional term related to the change of fabric anisotropy. The constitutive equations regarding the “force” terms are also proposed. All the “fabric” or “force” terms are modelled to tend toward their critial state value, which agrees with Li and Dafalias’s (J Eng Mech 138(3):263–275, 2012. https://doi.org/10.1061/(ASCE)EM.1943-7889.0000324) basic philosophy in their evolution equation for the fabric tensor. These equations along with the SFF equation form a constitutive model.
Heitor, A & Ngo, T 2019, 'Editorial', Proceedings of the Institution of Civil Engineers - Ground Improvement, vol. 172, no. 4, pp. 211-212.
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Hoque, M, Tasfia, S, Ahmed, N & Pradhan, B 2019, 'Assessing Spatial Flood Vulnerability at Kalapara Upazila in Bangladesh Using an Analytic Hierarchy Process', Sensors, vol. 19, no. 6, pp. 1302-1302.
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Floods are common natural disasters worldwide, frequently causing loss of lives and huge economic and environmental damages. A spatial vulnerability mapping approach incorporating multi-criteria at the local scale is essential for deriving detailed vulnerability information for supporting flood mitigation strategies. This study developed a spatial multi-criteria-integrated approach of flood vulnerability mapping by using geospatial techniques at the local scale. The developed approach was applied on Kalapara Upazila in Bangladesh. This study incorporated 16 relevant criteria under three vulnerability components: physical vulnerability, social vulnerability and coping capacity. Criteria were converted into spatial layers, weighted and standardised to support the analytic hierarchy process. Individual vulnerability component maps were created using a weighted overlay technique, and then final vulnerability maps were produced from them. The spatial extents and levels of vulnerability were successfully identified from the produced maps. Results showed that the areas located within the eastern and south-western portions of the study area are highly vulnerable to floods due to low elevation, closeness to the active channel and more social components than other parts. However, with the integrated coping capacity, western and south-western parts are highly vulnerable because the eastern part demonstrated particularly high coping capacity compared with other parts. The approach provided was validated by qualitative judgement acquired from the field. The findings suggested the capability of this approach to assess the spatial vulnerability of flood effects in flood-affected areas for developing effective mitigation plans and strategies.
Hoque, MA-A, Ahmed, N, Pradhan, B & Roy, S 2019, 'Assessment of coastal vulnerability to multi-hazardous events using geospatial techniques along the eastern coast of Bangladesh', Ocean & Coastal Management, vol. 181, pp. 104898-104898.
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© 2019 Elsevier Ltd The eastern coastal region of Bangladesh, which has a 377 km-long coastline, is highly vulnerable to multi-hazardous events, such as tropical cyclones, coastal floods, coastal erosion and salinity intrusion. The vulnerability of this coastal region is likely to increase under the future climate change context. This research aims to develop a coastal vulnerability index (CVI) of multi-hazardous events for the eastern coastal region of Bangladesh. Eight parameters, mostly focused on physical vulnerability, were considered in this study. Various thematic layers were prepared for each parameter using spatial techniques, and all parameters were assigned a vulnerability ranking. Finally, a CVI was developed and the related values were categorised into five distinct classes (i.e., very high, high, moderate, low, and very low). Results indicate that approximately 121 km (32%) of the coastline of the study area is in high-to very high-vulnerability zones. Low elevations, gentle slopes, high storm surge impacts, sandy coastlines, high shoreline erosion rates and high sea-level changes are the most important factors of high to very-high vulnerability zones. The moderately vulnerable area covers approximately 119 km (32%) of the coastline. Meanwhile, 78 (21%) and 59 (16%) km of the coastlines are in low-to very low-vulnerability zones, respectively. These coastlines are characterised by steep slopes with high elevations, low tide range and storm surge heights as well as less erosion. The CVI results were validated by qualitative observations acquired from the field. The findings of this study can be applied by policymakers and administrators to develop effective mitigation plans and minimise the likely impacts of coastal multi-hazards.
Hoque, MA-A, Pradhan, B, Ahmed, N & Roy, S 2019, 'Tropical cyclone risk assessment using geospatial techniques for the eastern coastal region of Bangladesh', Science of The Total Environment, vol. 692, pp. 10-22.
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© 2019 Elsevier B.V. Tropical cyclones frequently affect millions of people, damaging properties, livelihoods and environments in the coastal region of Bangladesh. The intensity and extent of tropical cyclones and their impacts are likely to increase in the future due to climate change. The eastern coastal region of Bangladesh is one of the most cyclone-affected coastal regions. A comprehensive spatial assessment is therefore essential to produce a risk map by identifying the areas under high cyclone risks to support mitigation strategies. This study aims to develop a comprehensive tropical cyclone risk map using geospatial techniques and to quantify the degree of risk in the eastern coastal region of Bangladesh. In total, 14 spatial criteria under three risk components, namely, vulnerability and exposure, hazard, and mitigation capacity, were assessed. A spatial layer was created for each criterion, and weighting was conducted following the Analytical Hierarchy Process. The individual risk component maps were generated from their indices, and subsequently, the overall risk map was produced by integrating the indices through a weighted overlay approach. Results demonstrate that the very-high risk zone covered 9% of the study area, whereas the high-risk zone covered 27%. Specifically, the south-western (Sandwip and Sonagazi), western (Patiya, Kutubdia, Maheshkhali, Chakaria, Cox's Bazar and Chittagong Sadar) and south-western (Teknaf) regions of the study site are likely to be under a high risk of tropical cyclone impacts. Low and very-low hazard zones constitute 11% and 28% of the study area, respectively, and most of these areas are located inland. The results of this study can be used by the concerned authorities to develop and apply effective cyclone impact mitigation plans and strategies.
Hossain, N & Mahlia, TMI 2019, 'Progress in physicochemical parameters of microalgae cultivation for biofuel production', Critical Reviews in Biotechnology, vol. 39, no. 6, pp. 835-859.
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© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. Microalgae have been exploited for biofuel generation in the current era due to its enormous energy content, fast cellular growth rate, inexpensive culture approaches, accumulation of inorganic compounds, and CO2 sequestration. Currently, research is ongoing towards the advancement of the microalgae cultivation parameters to enhance the biomass yield. The main objective of this study was to delineate the progress of physicochemical parameters for microalgae cultivation such as gaseous transfer, mixing, light demand, temperature, pH, nutrients and the culture period. This review demonstrates the latest research trends on mass transfer coefficient of different microalgae culturing reactors, gas velocity optimization, light intensity, retention time, and radiance effects on microalgae cellular growth, temperature impact on chlorophyll production, and nutrient dosage ratios for cellulosic metabolism to avoid nutrient deprivation. Besides that, cultivation approaches for microalgae associated with mathematical modeling for different parameters, mechanisms of microalgal growth rate and doubling time have been elaborately described. Along with that, this review also documents potential lipid-carbohydrate-protein enriched microalgae candidates for biofuel, biomass productivity, and different cultivation conditions including open-pond cultivation, closed-loop cultivation, and photobioreactors. Various photobioreactor types, the microalgae strain, productivity, advantages, and limitations were tabulated. In line with microalgae cultivation, this study also outlines in detail numerous biofuels from microalgae.
Hossain, N, Mahlia, TMI & Saidur, R 2019, 'Latest development in microalgae-biofuel production with nano-additives', Biotechnology for Biofuels, vol. 12, no. 1.
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© 2019 The Author(s). Background: Microalgae have been experimented as a potential feedstock for biofuel generation in current era owing to its' rich energy content, inflated growth rate, inexpensive culture approaches, the notable capacity of CO2 fixation, and O2 addition to the environment. Currently, research is ongoing towards the advancement of microalgal-biofuel technologies. The nano-additive application has been appeared as a prominent innovation to meet this phenomenon. Main text: The main objective of this study was to delineate the synergistic impact of microalgal biofuel integrated with nano-additive applications. Numerous nano-additives such as nano-fibres, nano-particles, nano-tubes, nano-sheets, nano-droplets, and other nano-structures' applications have been reviewed in this study to facilitate microalgae growth to biofuel utilization. The present paper was intended to comprehensively review the nano-particles preparing techniques for microalgae cultivation and harvesting, biofuel extraction, and application of microalgae-biofuel nano-particles blends. Prospects of solid nano-additives and nano-fluid applications in the future on microalgae production, microalgae biomass conversion to biofuels as well as enhancement of biofuel combustion for revolutionary advancement in biofuel technology have been demonstrated elaborately by this review. This study also highlighted the potential biofuels from microalgae, numerous technologies, and conversion processes. Along with that, the study recounted suitability of potential microalgae candidates with an integrated design generating value-added co-products besides biofuel production. Conclusions: Nano-additive applications at different stages from microalgae culture to end-product utilization presented strong possibility in mercantile approach as well as positive impact on the environment along with valuable co-products generation into the near future.
Hossain, N, Mahlia, TMI, Zaini, J & Saidur, R 2019, 'Techno‐economics and Sensitivity Analysis of Microalgae as Commercial Feedstock for Bioethanol Production', Environmental Progress & Sustainable Energy, vol. 38, no. 5, pp. 13157-13157.
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The foremost purpose of this techno‐economic analysis (TEA) modeling was to predict a harmonized figure of comprehensive cost analysis for commercial bioethanol generation from microalgae species in Brunei Darussalam based on the conventional market scenario. This model was simulated to set out economic feasibility and probabilistic assumption for large‐scale implementations of a tropical microalgae species, Chlorella vulgaris, for a bioethanol plant located in the coastal area of Brunei Darussalam. Two types of cultivation systems such as closed system (photobioreactor—PBR) and open pond approaches were anticipated for a total approximate biomass of 220 t year−1 on 6 ha coastal areas. The biomass productivity was 56 t ha−1 for PBR and 28 t ha−1 for pond annually. The plant output was 58.90 m3 ha−1 for PBR and 24.9 m3 ha−1 for pond annually. The total bioethanol output of the plant was 57,087.58 gal year−1 along with the value added by‐products (crude bio‐liquid and slurry cake). The total production cost of this project was US$2.22 million for bioethanol from microalgae and total bioethanol selling price was US$2.87 million along with the by‐product sale price of US$1.6 million. A sensitivity analysis was conducted to forecast the uncertainty of this conclusive modeling. Different data sets through sensitivity analysis also presented positive impacts of economical and environmental views. This TEA model is expected to be initialized to determine an alternative energy and also minimize environmental pollution. With this current modeling, microalgal‐bioethanol utilization mandated with gasoline as well as microalgae cultivation, biofuel production integrated with existing complementary industries, are strongly recommended for future applications. © 2019 A...
Hossain, N, Razali, AN, Mahlia, TMI, Chowdhury, T, Chowdhury, H, Ong, HC, Shamsuddin, AH & Silitonga, AS 2019, 'Experimental Investigation, Techno-Economic Analysis and Environmental Impact of Bioethanol Production from Banana Stem', Energies, vol. 12, no. 20, pp. 3947-3947.
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Banana stem is being considered as the second largest waste biomass in Malaysia. Therefore, the environmental challenge of managing this huge amount of biomass as well as converting the feedstock into value-added products has spurred the demand for diversified applications to be implemented as a realistic approach. In this study, banana stem waste was experimented for bioethanol generation via hydrolysis and fermentation methods with the presence of Saccharomyces cerevisiae (yeast) subsequently. Along with the experimental analysis, a realistic pilot scale application of electricity generation from the bioethanol has been designed by HOMER software to demonstrate techno-economic and environmental impact. During sulfuric acid and enzymatic hydrolysis, the highest glucose yield was 5.614 and 40.61 g/L, respectively. During fermentation, the maximum and minimum glucose yield was 62.23 g/L at 12 h and 0.69 g/L at 72 h, respectively. Subsequently, 99.8% pure bioethanol was recovered by a distillation process. Plant modeling simulated operating costs 65,980 US$/y, net production cost 869347 US$ and electricity cost 0.392 US$/kWh. The CO2 emission from bioethanol was 97,161 kg/y and SO2 emission was 513 kg/y which is much lower than diesel emission. The overall bioethanol production from banana stem and application of electricity generation presented the approach economically favorable and environmentally benign.
Hossain, N, Zaini, J & Indra Mahlia, TM 2019, 'Life cycle assessment, energy balance and sensitivity analysis of bioethanol production from microalgae in a tropical country', Renewable and Sustainable Energy Reviews, vol. 115, pp. 109371-109371.
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© 2019 Elsevier Ltd Overuse of petroleum and ongoing carbon-di-oxide (CO2) rise in the air of Brunei Darussalam has been emerged as a major environmental concern in this country. To resolve this issue, a comprehensive life cycle assessment (LCA) of alternative biofuel, bioethanol production from microalgae was demanded for realistic implementation. Therefore, LCA of bioethanol production from microalgae in terms of CO2 emission and energy balance was investigated based on the scenario of industrial-scale in Brunei Darussalam. This study demonstrated that 220 tons microalgae biomass was cultivated on 6 ha offshore lands for commercial bioethanol generation. The annual outcome of this commercial bioethanol plant has revealed net CO2 balance 218.86 ton. From the energy perspective, this study manifested itself as favourable with net energy ratio, 0.45 and net energy balance, −2749.6 GJ y−1. Apart from CO2 balance and energy generation aspect, the project demanded low water and land footprints. For photobioreactor cultivation, water and land footprints were 2 m3 GJ−1 and 2 m2 GJ−1, respectively as well as for open pond approach, they were 87 m3 GJ−1 and 13 m2 GJ−1, respectively. The project also presented microalgae growth supplements (phosphorus and nitrogen) accumulation possibilities from wastewater of manure and industries which is another positive aspect for benign environment. Overall, the commercial plant presented low CO2 emission, low land and water demand for microalgae cultivation, alternative eco-friendly and cheaper nutrients sources, quite high energy generation with main product and by-products. Thus, this study projected positive impact on energy and environmental aspects of microalgae-to-bioethanol conversion.
Hossain, N, Zaini, J & Mahlia, TMI 2019, 'Experimental investigation of energy properties forStigonematalessp. microalgae as potential biofuel feedstock', International Journal of Sustainable Engineering, vol. 12, no. 2, pp. 123-130.
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© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. Microalgae has been considered potential biofuel source from the last decade owing to its versatile perspectives such as excellent capability of CO 2 capture and sequestration, water treatment, prolific growth rate and enormous energy content. Thus, energy research on microalgae is being harnessed to mitigate CO 2 and meet future energy demands. This study investigated the bioenergy potential of native blue-green microalgae consortium as initial energy research on microalgae in Brunei Darussalam. The local species of microalgae were assembled from rainwater drains, the species were identified as Stigonematales sp. and physical properties were characterised. Sundried biomass with moisture content ranging from 6.5% to 7.37% was measured to be used to determine the net and gross calorific value and they were 7.98 MJ/kg-8.57 MJ/kg and 8.70 MJ/kg-9.45 MJ/kg, respectively. Besides that, the hydrogen content, ash content, volatile matter, and bulk density were also experimented and they were 2.56%-3.15%, 43.6%-36.71%, 57–38%-63.29% and 661.2 kg/m 3 -673.07 kg/m 3 , respectively. Apart from experimental values, other physical bioenergy parameters were simulated and they were biomass characteristic index 61,822.29 kg/m 3 -62,341.3 kg/m 3 , energy density 5.27 GJ/m 3 -5.76G J/m 3 and fuel value index 86.19–88.54. With these experimental results, microalgae manifested itself a potential source of biofuel feedstock for heat and electricity generation, a key tool to bring down the escalated atmospheric greenhouse gases and an alternation for fossil fuel.
Hossain, N, Zaini, J, Mahlia, TMI & Azad, AK 2019, 'Elemental, morphological and thermal analysis of mixed microalgae species from drain water', Renewable Energy, vol. 131, pp. 617-624.
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© 2018 Elsevier Ltd In this study, Stigonematales sp. microalgae were collected from drain water and characterized for its’ morphological edifice, elemental composition, thermal condition and energy generation capacity by using scanning electron microscopy, energy dispersive X-ray, thermogravimetric analyzer and bomb calorimeter, respectively. Scanning electron micrographs revealed the top view of microalgae and ash pellet with carbon coated specimens at low voltage (5.0 kV) through the secondary electron image detector. Elemental analysis revealed all the major and minor constituents of this microalgae species and its’ ash in terms of dry weight (%) and atomic weight (%). Thermogravimetric analysis was conducted at heating rate, 10 °C/min and this experimental results determined moisture content, volatile matter, ash content and fixed carbon of the sample with 4.5%, 35%, 39.5% and 21%, respectively. Microalgae powder blended with bituminous coal by 75%, 50% and 25% measured calorific value 14.07 MJ/kg, 19.88 MJ/kg and 26.42 MJ/kg, respectively. Microalgae (75%) -coal (25%) blend showed excellent amount of energy content, 24.59 MJ/kg. Microalgae blended with coal unveiled an outstanding outcome with elevation of the volatile matter and drop of the ash content. Optimization of microalgae-coal blend in large-scale application can initiate bright future in renewable energy exploration.
Hossain, SM, Park, MJ, Park, HJ, Tijing, L, Kim, J-H & Shon, HK 2019, 'Preparation and characterization of TiO2 generated from synthetic wastewater using TiCl4 based coagulation/flocculation aided with Ca(OH)2', Journal of Environmental Management, vol. 250, pp. 109521-109521.
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This study focused on the preparation of undoped and Ca-doped titania from flocculation generated sludge. Initially, TiCl4 was utilised to perform coagulation and flocculation in synthetic wastewater and an optimised dose of coagulant was determined by evaluating the turbidity, dissolved organic carbon (DOC) and zeta potential of the treated water. Later, using Ca(OH)2 as a coagulant aid, the effects on effluent pH, turbidity and DOC removal were investigated. Both Ca-doped and undoped anatase TiO2 were prepared from the flocculated sludge for morphological and photocatalytic evaluation. During the standalone use of TiCl4, maximum turbidity and DOC removal were found at 11.63 and 14.54 mg Ti/L, respectively. At the corresponding coagulant dose, rapid deprotonation of water caused the pH of the effluent to reach below 3.77 mg Ti/L. Whereas, when using Ca(OH)2 as a coagulant aid, a neutral pH (7.26) was attained at a simultaneous dosing of 32.40 mg Ca/L and 14.54 mg Ti/L. When aided with Ca(OH)2, the turbidity removal was further increased by 54.28% and the DOC removal was somewhat similar to the standalone use of TiCl4. TiO2 was prepared by incinerating the collected sludge at 600 °C for 2 h. Both XRD and SEM analysis were conducted to observe the morphology of the prepared titania. The XRD pattern of the TiO2 showed only an anatase phase along with the presence of a high atomic proportion of Ca (4.14%). Consequently, a high amount of Ca atoms inhibited the level of TiO2 phase and no obvious presence of CaO was observed. The prepared Ca-doped TiO2 at the optimised dose of Ca(OH)2 was found to be inferior to the undoped TiO2 during the photodegradation of acetaldehyde. However, a reduced dose of Ca(OH)2 (<15 mg Ca/L) exhibited a substantial increase in photoactivity under UV irradiance.
How, HG, Teoh, YH, Masjuki, HH, Nguyen, H-T, Kalam, MA, Chuah, HG & Alabdulkarem, A 2019, 'Impact of two-stage injection fuel quantity on engine-out responses of a common-rail diesel engine fueled with coconut oil methyl esters-diesel fuel blends', Renewable Energy, vol. 139, pp. 515-529.
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Howard, D, Macsween, K, Edwards, GC, Desservettaz, M, Guérette, E-A, Paton-Walsh, C, Surawski, NC, Sullivan, AL, Weston, C, Volkova, L, Powell, J, Keywood, MD, Reisen, F & (Mick) Meyer, CP 2019, 'Investigation of mercury emissions from burning of Australian eucalypt forest surface fuels using a combustion wind tunnel and field observations', Atmospheric Environment, vol. 202, pp. 17-27.
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© 2018 Environmental cycling of the toxic metal mercury (Hg) is ubiquitous, and still not completely understood. Volatilisation and emission of mercury from vegetation, litter and soil during burning represents a significant return pathway for previously-deposited atmospheric mercury. Rates of such emission vary widely across ecosystems as they are dependent on species-specific uptake of atmospheric mercury as well as fire return frequencies. Wildfire burning in Australia is currently thought to contribute between 1 and 5% of the global total of mercury emissions, yet no modelling efforts to date have utilised local mercury emission factors (mass of emitted mercury per mass of dry fuel) or local mercury emission ratios (ratio of emitted mercury to another emitted species, typically carbon monoxide). Here we present laboratory and field investigations into mercury emission from burning of surface fuels in dry sclerophyll forests, native to the temperate south-eastern region of Australia. From laboratory data we found that fire behaviour — in particular combustion phase — has a large influence on mercury emission and hence emission ratios. Further, emission of mercury was predominantly in gaseous form with particulate-bound mercury representing <1% of total mercury emission. Importantly, emission factors and emission ratios with respect to carbon monoxide and carbon dioxide, from both laboratory and field data all show that gaseous mercury emission from biomass burning in Australian dry sclerophyll forests is currently overestimated by around 60%. Based on these results, we recommend a mercury emission factor of 28.7 ± 8.1 μg Hg kg−1 dry fuel, and emission ratio of gaseous elemental mercury relative to carbon monoxide of 0.58 ± 0.01 × 10−7, for estimation of mercury release from the combustion of Australian dry sclerophyll litter.
Hu, Y, Tang, Z, Li, W, Li, Y & Tam, VWY 2019, 'Physical-mechanical properties of fly ash/GGBFS geopolymer composites with recycled aggregates', Construction and Building Materials, vol. 226, pp. 139-151.
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© 2019 Elsevier Ltd The properties of fly ash and ground granulated blast furnace slag (GGBFS) combination based geopolymer composites containing recycled aggregate are investigated in this study, which obtained from construction and demolition wastes. The effects of recycled aggregate replacement and GGBFS inclusion on the physical and mechanical properties of geopolymer composites were investigated in this study. The scanning electron microscopic (SEM) were conducted to provide a thorough insight into the characterization of microstructures. The results reveal that using recycled aggregate has an insignificant impact on workability and setting time, while it causes a reduction in physical and mechanical properties. The inclusion of GGBFS reduces workability and setting time. However, improved physical and mechanical properties can be achieved in the geopolymer composites after the incorporation of GGBFS, and this effect is more prominent in the geopolymer composites containing recycled aggregates. The water absorption and sorptivity exhibit a strong correlation with the volume of permeable voids of geopolymer composites. Besides, very good relationships were established between the compressive strength and other mechanical properties, and these relationships fitted reasonably well with the other predictions.
Huang, L, Liu, Z, Wu, C & Liang, J 2019, 'The scattering of plane P, SV waves by twin lining tunnels with imperfect interfaces embedded in an elastic half-space', Tunnelling and Underground Space Technology, vol. 85, pp. 319-330.
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© 2018 Elsevier Ltd A viscous-slip interface model is employed to simulate the contact between the tunnels lining and the surrounding rock, and the scattering of P, SV waves by twin shallowly buried lining tunnels is investigated with the indirect boundary integral equation method (IBIEM). The amplification effect of the dynamic stress concentration of the lining and the surface displacement near the tunnels is examined. It is evident that the slipping-stiffness coefficient and viscosity coefficient at the lining-surrounding rock interface have a significant influence on the dynamic stress distribution and the nearby surface displacement response of the lining tunnel, while the influence characteristics strongly depend on the incident wave type, frequency and angle. Under the incidence of low frequency wave, as a whole, with the increase of the sliding stiffness, the hoop stress increases gradually for plane P and SV waves; while in the resonance frequency (the incident wave frequency is consistent with the natural frequency of the soil column above the tunnels), specially for high-frequency band, the dynamic stress concentration effect is more significant for smaller sliding stiffness. With the increase of viscosity coefficient, the dynamic stress concentration factor inside the lining gradually decreases. Also, the tunnels with viscous-slip interfaces have a more significant amplification effect on the nearby surface displacement amplitude. Moreover, the hoop stress of the twin tunnels may be obviously larger than that of single tunnel in most cases. The dynamic analysis of the underground structure under the actual strong dynamic loading should consider the influence of the slip effect between the lining and surrounding rock interface.
Huang, Q-S, Wei, W, Sun, J, Mao, S & Ni, B-J 2019, 'Hexagonal K2W4O13 Nanowires for the Adsorption of Methylene Blue', ACS Applied Nano Materials, vol. 2, no. 6, pp. 3802-3812.
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© 2019 American Chemical Society. In this study, novel hexagonal K2W4O13 (h-K2W4O13) nanowires were strategically synthesized via a facial hydrothermal method, which exhibited excellent adsorption capacities for wastewater treatment. The inorganic agent K2SO4 was used as a structure-directing agent to scaffold the tunnel structure of h-K2W4O13 and form the one-dimensional structure. Through increasing the relative molar ratio of K2SO4 to Na2WO4 precursor, the pure-phase h-WO3 nanorods and h-K2W4O13 nanowires were obtained, attributing to the competitive electrostatic adsorption between K+ ions and Na+ ions on h-WO3 nuclei. With a smaller hydrated radius in the solution (dK+ = 3.31 Å, dNa+= 3.58 Å), K+ exhibited superior affinity compared to Na+ with the negatively charged h-WO3 nuclei because of a larger charge density, resulting in the formation of h-K2W4O13. Adsorption experimental results showed that 89.4% of methylene blue was removed by h-K2W4O13 in the first 5 min (99% in 1 h) and the maximum uptake capacity reached 204.08 mg g-1. In addition, the novel h-K2W4O13 exhibited acid or alkali resistance and good reusability, revealed by the stable adsorption capacity in a wide pH range of 3.0-11.0 and five-run recycle tests. The large specific area, high proportion of effective pore volume, and abundant hydroxyl groups of the synthesized h-K2W4O13 resulted in excellent adsorption performance for methylene blue.
Huang, Q-S, Wu, W, Wei, W & Ni, B-J 2019, 'Polyethylenimine modified potassium tungsten oxide adsorbent for highly efficient Ag+ removal and valuable Ag0 recovery', Science of The Total Environment, vol. 692, pp. 1048-1056.
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Elemental Ag0 is well known for its remarkable catalytic and antibacterial properties, thus the regeneration of valuable Ag0 metal from Ag+ wastewater is of great significance. In this study, a novel polyethylenimine (PEI) modified potassium tungsten oxide (N-K2W4O13) adsorbent was prepared for Ag+ removal and reduction to Ag0 using glutaraldehyde as crosslinking agent. XPS and FT-IR spectra verified PEI successfully anchored on the surface O and W atoms of K2W4O13 through aldehyde bridges. The content of PEI in N-K2W4O13 was calculated as 8.74wt% by TG curve. A heterogeneous PEI coating was observed in the SEM and TEM images. The N-K2W4O13 exhibited larger Ag+ uptake (48.25mg/g) than the raw K2W4O13 (42.50mg/g) though required a longer equilibrium time. This was due to the combined results of strong chelation and weak electrostatic repulsion that meanwhile occurring on the positive-charged surface of N-K2W4O13. The maximum Ag+ uptake on N-K2W4O13 was 72.5mg/g, which was larger than many of the reported adsorbents. Furthermore, the prepared N-K2W4O13 displayed good anti-interference toward background ions (Na+, K+) and hold a stable Ag+ removal (>95%) after five runs of recycling tests. The mechanism studies elucidated that NH/N groups from the PEI modified N-K2W4O13 mainly accounted for the Ag+ adsorption and Ag0 recovery in the adsorption-reduction process. Ion-exchange between Ag+ and K+ from the N-K2W4O13 lattice also occurred. This work provided a facile method to synthesize a promising adsorbent for Ag+ wastewater remediation and valuable Ag0 recovery.
Huang, W-Y, Ngo, H-H, Lin, C, Vu, C-T, Kaewlaoyoong, A, Boonsong, T, Tran, H-T, Bui, X-T, Vo, T-D-H & Chen, J-R 2019, 'Aerobic co-composting degradation of highly PCDD/F-contaminated field soil. A study of bacterial community', Science of The Total Environment, vol. 660, pp. 595-602.
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This study investigated bacterial communities during aerobic food waste co-composting degradation of highly PCDD/F-contaminated field soil. The total initial toxic equivalent quantity (TEQ) of the soil was 16,004 ng-TEQ kg-1 dry weight. After 42-day composting and bioactivity-enhanced monitored natural attenuation (MNA), the final compost product's TEQ reduced to 1916 ng-TEQ kg-1 dry weight (approximately 75% degradation) with a degradation rate of 136.33 ng-TEQ kg-1 day-1. Variations in bacterial communities and PCDD/F degraders were identified by next-generation sequencing (NGS). Thermophilic conditions of the co-composting process resulted in fewer observed bacteria and PCDD/F concentrations. Numerous organic compound degraders were identified by NGS, supporting the conclusion that PCDD/Fs were degraded during food waste co-composting. Bacterial communities of the composting process were defined by four phyla (Proteobacteria, Actinobacteria, Bacteroidetes and Firmicutes). At the genus level, Bacillus (Firmicutes) emerged as the most dominant phylotype. Further studies on specific roles of these bacterial strains are needed, especially for the thermophiles which contributed to the high degradation rate of the co-co-composting treatment's first 14 days.
Huang, Y, Fu, J, Liu, A, Rao, R, Wu, D & Shen, J 2019, 'Model Test and Optimal Design of the Joint in a Sunflower Arch Bridge', Journal of Bridge Engineering, vol. 24, no. 2, pp. 04018121-04018121.
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© 2018 American Society of Civil Engineers. The sunflower arch bridge is a new type of reinforced concrete arch bridge that has been developed recently. Because of the complex constructional details, the stress distribution at the joint between the main arch and spandrel arch is very complicated. To explore the mechanical behavior of this new type of arch bridge, particularly the stress state at the joint of the arch, a 1:5-scaled model of a segment for a sunflower arch bridge was tested. The displacements and stresses at key locations of the tested model were recorded. The experimental results showed that the displacements of the main arch and spandrel arch under dead loads were notably small, which indicated that the global stiffness of the arch was sufficiently large. Moreover, the maximum tensile stress at the end of the spandrel arch subjected to dead loads was larger than the tensile strength of the concrete; therefore, the concrete in these regions is vulnerable to cracking. To avoid cracks at the end of the spandrel arch, an optimized design scheme was proposed for the joint using a steel I-beam to replace the concrete at the end of the spandrel arch. Design parameters were also suggested through a comprehensive parametric investigation based on finite-element analysis (FEA).
Huang, Y, Ng, ECY, Yam, Y-S, Lee, CKC, Surawski, NC, Mok, W-C, Organ, B, Zhou, JL & Chan, EFC 2019, 'Impact of potential engine malfunctions on fuel consumption and gaseous emissions of a Euro VI diesel truck', Energy Conversion and Management, vol. 184, pp. 521-529.
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© 2019 Elsevier Ltd Although new vehicles are designed to comply with specific emission regulations, their in-service performance would not necessarily achieve them due to wear-and-tear and improper maintenance, as well as tampering or failure of engine control and exhaust after-treatment systems. In addition, there is a lack of knowledge on how significantly these potential malfunctions affect vehicle performance. This study was therefore conducted to simulate the effect of various engine malfunctions on the fuel consumption and gaseous emissions of a 16-tonne Euro VI diesel truck using transient chassis dynamometer testing. The simulated malfunctions included those that would commonly occur in the intake, fuel injection, exhaust after-treatment and other systems. The results showed that all malfunctions increased fuel consumption except for the malfunction of EGR fully closed which reduced fuel consumption by 31%. The biggest increases in fuel consumption were caused by malfunctions in the intake system (16%–43%), followed by the exhaust after-treatment (6%–30%), fuel injection (4%–24%) and other systems (6%–11%). Regarding pollutant emissions, the effect of engine malfunctions on HC and CO emissions was insignificant, which remained unchanged or even reduced for most cases. An exception was EGR fully open which increased HC and CO emissions by 343% and 1124%, respectively. Contrary to HC and CO emissions, NO emissions were significantly increased by malfunctions. The largest increases in NO emissions were caused by malfunctions in the after-treatment system, ranging from 38% (SCR) to 1606% (DPF pressure sensor). Malfunctions in the fuel injection system (24%–1259%) and intercooler (438%–604%) could also increase NO emissions markedly. This study demonstrated clearly the importance of having properly functioning engine control and exhaust after-treatment systems to achieve the required performance of fuel consumption and pollutant emissions.
Huang, Y, Organ, B, Zhou, JL, Surawski, NC, Yam, Y-S & Chan, EFC 2019, 'Characterisation of diesel vehicle emissions and determination of remote sensing cutpoints for diesel high-emitters', Environmental Pollution, vol. 252, no. Part A, pp. 31-38.
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© 2019 Elsevier Ltd Diesel vehicles are a major source of air pollutants in cities and have caused significant health risks to the public globally. This study used both on-road remote sensing and transient chassis dynamometer to characterise emissions of diesel light goods vehicles. A large sample size of 183 diesel vans were tested on a transient chassis dynamometer to evaluate the emission levels of in-service diesel vehicles and to determine a set of remote sensing cutpoints for diesel high-emitters. The results showed that 79% and 19% of the Euro 4 and Euro 5 diesel vehicles failed the transient cycle test, respectively. Most of the high-emitters failed the NO limits, while no vehicle failed the HC limits and only a few vehicles failed the CO limits. Vehicles that failed NO limits occurred in both old and new vehicles. NO/CO2 ratios of 57.30 and 22.85 ppm/% were chosen as the remote sensing cutpoints for Euro 4 and Euro 5 high-emitters, respectively. The cutpoints could capture a Euro 4 and Euro 5 high-emitter at a probability of 27% and 57% with one snapshot remote sensing measurement, while only producing 1% of false high-emitter detections. The probability of high-emitting events was generally evenly distributed over the test cycle, indicating that no particular driving condition produced a higher probability of high-emitting events. Analysis on the effect of cutpoints on real-driving diesel fleet was carried out using a three-year remote sensing program. Results showed that 36% of Euro 4 and 47% of Euro 5 remote sensing measurements would be detected as high-emitting using the proposed cutpoints. In-service diesel vehicles emit low CO and HC but high NO.
Huang, Y, Surawski, NC, Organ, B, Zhou, JL, Tang, OHH & Chan, EFC 2019, 'Fuel consumption and emissions performance under real driving: Comparison between hybrid and conventional vehicles', Science of The Total Environment, vol. 659, pp. 275-282.
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© 2018 Elsevier B.V. Hybrid electric vehicles (HEVs) are perceived to be more energy efficient and less polluting than conventional internal combustion engine (ICE) vehicles. However, increasing evidence has shown that real-driving emissions (RDE) could be much higher than laboratory type approval limits and the advantages of HEVs over their conventional ICE counterparts under real-driving conditions have not been studied extensively. Therefore, this study was conducted to evaluate the real-driving fuel consumption and pollutant emissions performance of HEVs against their conventional ICE counterparts. Two pairs of hybrid and conventional gasoline vehicles of the same model were tested simultaneously in a novel convoy mode using two portable emission measurement systems (PEMSs), thus eliminating the effect of vehicle configurations, driving behaviour, road conditions and ambient environment on the performance comparison. The results showed that although real-driving fuel consumption for both hybrid and conventional vehicles were 44%–100% and 30%–82% higher than their laboratory results respectively, HEVs saved 23%–49% fuel relative to their conventional ICE counterparts. Pollutant emissions of all the tested vehicles were lower than the regulation limits. However, HEVs showed no reduction in HC emissions and consistently higher CO emissions compared to the conventional ICE vehicles. This could be caused by the frequent stops and restarts of the HEV engines, as well as the lowered exhaust gas temperature and reduced effectiveness of the oxidation catalyst. The findings therefore show that while achieving the fuel reduction target, hybridisation did not bring the expected benefits to urban air quality.
Huang, YQ, Fu, JY, Liu, AR, Pi, YL, Wu, D & Gao, W 2019, 'Effect of concrete creep on dynamic stability behavior of slender concrete-filled steel tubular column', Composites Part B: Engineering, vol. 157, pp. 173-181.
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© 2018 Elsevier Ltd An analytical procedure for dynamic stability of CFST column accounting for the creep of concrete core is proposed. The long-term effect of creep of concrete core is formulated based on the creep model by the ACI 209 committee and the age-adjusted effective modulus method (AEMM). The equations of boundary frequencies accounting for the effects of concrete creep are derived by the Bolotin's theory and solved as a quadratic eigenvalue problem. The effectiveness of the proposed method and the characteristics of time-varying distribution of instability regions are numerically surveyed. It is shown that the CFST column becomes dynamically unstable even when the sum of the sustained static load and the amplitude of the dynamic excitation is much lower than the static instability load. It is also found that due to the time effects of concrete creep under the sustained static load, the same excitation, that cannot induce dynamic instability in the early stage of sustained loading, can induce the dynamic instability in a few days later. The critical amplitude and frequency of the dynamic excitation can decrease by 6% and 3% in 5 days, and 11% and 6% in 100 days.
Ibrar, I, Naji, O, Sharif, A, Malekizadeh, A, Alhawari, A, Alanezi, AA & Altaee, A 2019, 'A Review of Fouling Mechanisms, Control Strategies and Real-Time Fouling Monitoring Techniques in Forward Osmosis', Water, vol. 11, no. 4, pp. 695-695.
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Forward osmosis has gained tremendous attention in the field of desalination and wastewater treatment. However, membrane fouling is an inevitable issue. Membrane fouling leads to flux decline, can cause operational problems and can result in negative consequences that can damage the membrane. Hereby, we attempt to review the different types of fouling in forward osmosis, cleaning and control strategies for fouling mitigation, and the impact of membrane hydrophilicity, charge and morphology on fouling. The fundamentals of biofouling, organic, colloidal and inorganic fouling are discussed with a focus on recent studies. We also review some of the in-situ real-time online fouling monitoring technologies for real-time fouling monitoring that can be applicable to future research on forward osmosis fouling studies. A brief discussion on critical flux and the coupled effects of fouling and concentration polarization is also provided.
Idroes, R, Yusuf, M, Saiful, S, Alatas, M, Subhan, S, Lala, A, Muslem, M, Suhendra, R, Idroes, GM, Marwan, M & Mahlia, TMI 2019, 'Geochemistry Exploration and Geothermometry Application in the North Zone of Seulawah Agam, Aceh Besar District, Indonesia', Energies, vol. 12, no. 23, pp. 4442-4442.
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A geochemistry study has been done in four geothermal manifestations—Ie-Seu’um, Ie-Brôuk, Ie-Jue and the Van-Heutz crater—located in the north zone of Seulawah Agam mountain (Aceh Besar District, Indonesia). The study was performed through water and gas analysis. Water analysis were done for all geothermal manifestations, but gas analysis was only done for the Ie-Jue manifestation that has fumaroles. Cation and anion contents were analyzed by ion chromatography, ICP-OES, alkalimetry titrations, and spectrophotometry, meanwhile isotopes were measured by a Liquid Water Isotope Analyzer. The resulting data were used for fluid and gas geothermometry calculations, and plotted in a FT-CO2 Cross-Plot and a CH4-CO2-H2S triangle diagram to obtain reservoir temperatures. The data were also plotted by a Cl-HCO3-SO4 triangle and Piper diagram to obtain the water type and dominant chemical composition, a Na-K-Mg triangle diagram to obtain fluid equilibria, the isotope ratio in the stable isotope plot to obtain the origin of water, and a N2-He-Ar triangle diagram to establish the origin of fumaroles. The water analysis results showed that (1) Ie-Seu’um has an average reservoir temperature of 241.9 ± 0.3 °C, a chloride water type, a dominant Na-K-Cl chemical composition, a mature water fluid equilibrium, and water of meteoric origin; (2) Ie-Brôuk has an average reservoir temperature of 321.95 ± 13.4 °C, a bicarbonate water type, a dominant Na-Ca-HCO3chemical composition, an immature water fluid equilibrium, and water of meteoric origin; (3) Ie-Jue has an average reservoir temperature of 472.4 ± 91.4 °C, a sulphate water type, a dominant Ca-SO4 chemical composition, an immature water fluid equilibrium and water of meteoric origin; and (4) the Van-Heutz crater has an average reservoir temperature of 439.3 ± 95.3 °C, a sulphate water type, a dominant Ca-SO4 chemical composition, an immature water fluid equilibrium and water of magmatic origin. The results of our ...
Indraratna, B, Babar Sajjad, M, Ngo, T, Gomes Correia, A & Kelly, R 2019, 'Improved performance of ballasted tracks at transition zones: A review of experimental and modelling approaches', Transportation Geotechnics, vol. 21, pp. 100260-100260.
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© 2019 Elsevier Ltd Track transitions such as bridge approaches, road crossings and shifts from slab track to ballasted track are common locations where track degradation accelerates due to dynamic and high impact forces; as a consequence there is higher differential settlement. These types of discontinuities cause an abrupt change in the structural response of the track due mainly to variations in stiffness and track damping. Track transition zones are prone to an accelerated deterioration of track material and geometry that leads to increased maintenance costs. Track deterioration also leads to vehicle degradation due to enhanced acceleration, low frequency oscillation, and high frequency vibrations. While ballast deterioration is a major factor affecting the stability and longevity of rail tracks, the cost of tackling transition related problems that detract from passenger comfort is also high. A good transition zone lessens the impact of dynamic load of moving trains by minimising the abrupt variations in track stiffness and ensuring a smooth and gradual change from a less stiff (ballasted track) to a stiff (slab track) structure. This paper presents a critical review of various problems associated with transition zones and the measures adopted to mitigate them; it also includes critical review of research work carried out using large-scale laboratory testing, mathematical and computational modelling and field measurements on track transition zones.
Indraratna, B, Qi, Y, Heitor, A & Vinod, JS 2019, 'The influence of rubber crumbs on the critical state behavior of waste mixtures', E3S Web of Conferences, vol. 92, pp. 06004-06004.
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The practical application of waste materials such as steel furnace slag (SFS) and coal wash (CW) is becoming more prevalent in many geotechnical projects. It was found that the inclusion of rubber crumbs (RCs) from recycled tyres into mixtures of SFS and CW not only solves the problem of large stockpiles of waste tyres, it also can provide an energy-absorbing medium that will reduce track degradation. In order to investigate the influence of RC on the geotechnical properties of the granular waste matrix (SFS+CW+RC), a series of monotonic consolidated drained triaxial tests were conducted on waste mixtures. The test results reveal that the inclusion of RC significantly affects the geotechnical properties of the waste mixtures, especially their critical state behaviour. Specifically, the waste matrix can achieve a critical state with a low RC content (<20%), whereas those mixtures with higher RC contents (20-40%) cannot attain a critical state within the ultimate strain capacity that can be applied to specimens using the traditional triaxial equipment. Therefore, for the waste matrix with higher RC contents extrapolation of the measured volumetric strains had to be adopted to obtain the appropriate critical state parameters. Moreover, the influence of energy absorbing property by adding RC on the critical state behaviour has also been captured through an empirical equation.
Indraratna, B, Qi, Y, Ngo, TN, Rujikiatkamjorn, C, Neville, T, Ferreira, FB & Shahkolahi, A 2019, 'Use of Geogrids and Recycled Rubber in Railroad Infrastructure for Enhanced Performance', Geosciences, vol. 9, no. 1, pp. 30-30.
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Railway tracks are conventionally built on compacted ballast and structural fill layers placed above the natural (subgrade) foundation. However, during train operations, track deteriorations occur progressively due to ballast degradation. The associated track deformation is usually accompanied by a reduction in both load bearing capacity and drainage, apart from imposing frequent track maintenance. Suitable ground improvement techniques involving plastic inclusions (e.g., geogrids) and energy absorbing materials (e.g., rubber products) to enhance the stability and longevity of tracks have become increasingly popular. This paper presents the outcomes from innovative research and development measures into the use of plastic and rubber elements in rail tracks undertaken at the University of Wollongong, Australia, over the past twenty years. The results obtained from laboratory tests, mathematical modelling and numerical modelling reveal that track performance can be improved significantly by using geogrid and energy absorbing rubber products (e.g., rubber crumbs, waste tire-cell and rubber mats). Test results show that the addition of rubber materials can efficiently improve the energy absorption of the structural layer and also reduce ballast breakage. Furthermore, by incorporating the work input parameters, the energy absorbing property of the newly developed synthetic capping layer is captured by correct modelling of dilatancy. In addition, the laboratory behavior of tire cells and geogrids has been validated by numerical modelling (i.e., Finite Element Modelling-FEM, Discrete Element—DEM), and a coupled DEM-FEM modelling approach is also introduced to simulate ballast deformation.
Indraratna, B, Rujikiatkamjorn, C, Baral, P & Ameratunga, J 2019, 'Performance of marine clay stabilised with vacuum pressure: Based on Queensland experience', Journal of Rock Mechanics and Geotechnical Engineering, vol. 11, no. 3, pp. 598-611.
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© 2018 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences Stabilising soft marine clay and estuarine soils via vacuum preloading has become very popular in Australasia over the past decades because it is a cost-effective and time-efficient approach. In recent times, new land on areas outside but adjacent to existing port amenities, the Fisherman Islands at the Port of Brisbane (POB), was reclaimed to cater for an increase in trade activities. A vacuum preloading method combined with surcharge to stabilise the deep layers of soil was used to enhance the application of prefabricated vertical drains (PVDs). This paper describes the performance of this combined surcharge fill and vacuum system under the embankment and also compares it with a surcharge loading system to demonstrate the benefits of vacuum pressure over conventional fill. The performance of this embankment is also presented in terms of field monitoring data, and the relative performance of the vacuum together with non-vacuum systems is evaluated. An analytical solution to radial consolidation with time-dependent surcharge loading and vacuum pressure is also presented in order to predict the settlement and associated excess pore water pressure (EPWP) of deposits of thick soft clay.
Indraratna, B, Rujikiatkamjorn, C, Tawk, M & Heitor, A 2019, 'Compaction, degradation and deformation characteristics of an energy absorbing matrix', Transportation Geotechnics, vol. 19, pp. 74-83.
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© 2019 Elsevier Ltd The reuse of waste materials as an alternative to natural aggregates is becoming more popular in engineering projects. It offers a sustainable and economical solution to address the environmental concerns arising from the scarcity of natural quarries as well as the increase in waste generation. Coal wash (CW) and rubber crumbs (RC) are industrial by-products that could potentially be used in railway substructures. In this study, different RC levels are introduced into CW (i.e. CWRC mixture) to reduce potential breakage of CW and increase the ductility and energy absorbing capacity of the matrix. The compaction and degradation characteristics of CWRC mixtures to be used as a construction fill are investigated under five energy levels ranging from standard to modified Proctor compaction. An optimum compaction energy is determined so as to minimize breakage but still yield an acceptable void ratio (compact packing) to avoid excessive settlements. The compressibility of rubber particles and the induced change in the volume of solids is addressed with regard to the overall void ratio of the matrix. Furthermore, the results of triaxial tests on four CWRC mixtures compacted to the same void ratio under three different confining pressures (25, 50 and 75 kPa) are presented, and the effect of RC content on the stress-strain relationship is elucidated.
Isola, A, Mansor, S, Shafri, HM, Pradhan, B & Mansor, Y 2019, 'Impact of externai forces on the quality of digital elevation model derived from drone technology', International Journal of Geoinformatics, vol. 15, no. 1, pp. 81-91.
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Platform instability is one of the sources of error of Digital Elevation Model (DEM) derived from a low altitude aircraft. This paper examines the influence of atmospheric pressure (AP) on the DEM produced by drone system. To achieve the research objective, an experimental-based ftxed-wing drone platform was set up at the Universiti Putra Malaysia Campus. First, Ground Control Points (GCPs) and CheckPoints (CPs) were established within the study area by a real-time kinematic differential global positioning system. The drone flew seven times at different altitudes over the study area. In the process, an on-board canon digital camera took a series of overlapping photos. The photos were processed with an image-matching algorithm. Then orthorectified the photos using the GCPs. Photo orthorectification entails orientation of aerial photos with respect to the ground control points. It helps to remove distortions that might occur while acquiring or Processing the aerial photographs. In the end, seven DEMs were exported in tiff file format. Analysis of impact of AP on the resulting DEMs was conducted using a proposed model and obtained 0.072m, 0.05m, 0.014m, 0.0lm, 0.004m, 0.003m, and 0.002m for lOOm, I50m, 200m, 250m, 350m, 400m, and 500m altitudes, respectively. To confirm the efficiency of the proposed model, the results were tested using the CPs and their corresponding points on the DEMs and obtained root mean square error of 0.03m, O.OSm, 0.07m, O.lm, 13m, 0.14m, and 0.16m. On a final note, a close look at the validation and impact of AP results unveils a small gap. Hence, suggests that platform instability should be ignored amidst of other externai forces that can influence the performance of drone system.
Israr, J & Indraratna, B 2019, 'Study of Critical Hydraulic Gradients for Seepage-Induced Failures in Granular Soils', Journal of Geotechnical and Geoenvironmental Engineering, vol. 145, no. 7, pp. 04019025-04019025.
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© 2019 American Society of Civil Engineers. This paper reports on a series of laboratory hydraulic tests on a select range of granular soils compacted at relative densities between 0% and 100%. The critical hydraulic gradient at the onset of seepage failure (i.e., heave and suffusion) is considerably smaller than unity for internally unstable (i.e., nonuniform) sand-gravel mixtures due to stress reduction in their finer fraction. For example, stable uniform fine sands have been shown to exhibit heave at hydraulic gradients ≥1.0, whereas sand-gravel mixtures suffer from suffusion at hydraulic gradients ≥1.0. The boundary friction from the cell walls of test equipment would influence the development of heave, while suffusion is controlled by interparticle friction. In this study, the critical hydraulic gradient is modeled theoretically by considering the effects of interparticle and boundary frictions, and stress reduction in the soil. The experimental results from both this and past studies are used to verify the proposed model, which showed good agreement with experimental observations with less than 5% standard error.
Jafari, M, Verma, P, Bodisco, TA, Zare, A, Surawski, NC, Borghesani, P, Stevanovic, S, Guo, Y, Alroe, J, Osuagwu, C, Milic, A, Miljevic, B, Ristovski, ZD & Brown, RJ 2019, 'Multivariate analysis of performance and emission parameters in a diesel engine using biodiesel and oxygenated additive', Energy Conversion and Management, vol. 201, pp. 112183-112183.
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© 2019 Elsevier Ltd Rising concerns over environmental and health issues of internal combustion engines, along with growing energy demands, have motivated investigation into alternative fuels derived from biomasses, such as biodiesel. Investigating engine and exhaust emission behaviour of such alternative fuels is vital in order to assess suitability for further utilisation. Since many parameters are relevant, an effective multivariate analysis tool is required to identify the underlying factors that affect the engine performance and exhaust emissions. This study utilises principal component analysis (PCA) to present a comprehensive correlation of various engine performance and emission parameters in a compression ignition engine using diesel, biodiesel and triacetin. The results show that structure-borne acoustic emission is strongly correlated with engine parameters. Brake specific NOx, primary particle diameter and fringe length increases by increasing the rate of pressure rise. Longer ignition delay and higher engine speeds can increase the nucleation particle emissions. Higher air-fuel equivalence ratio can increase the oxidative potential of the soot by increasing fringe distance and tortuosity. The availability of oxygen in the cylinder, from the intake air or fuel, can increase soot aggregate compactness. Fuel oxygen content reduces particle mass and particle number in the accumulation mode; however, they increase the proportion of oxygenated organic species. PCA results for particle chemical and physical characteristics show that soot particles reactivity increases with fuel oxygen content.
Jahandari, S, Saberian, M, Tao, Z, Mojtahedi, SF, Li, J, Ghasemi, M, Rezvani, SS & Li, W 2019, 'Effects of saturation degrees, freezing-thawing, and curing on geotechnical properties of lime and lime-cement concretes', Cold Regions Science and Technology, vol. 160, pp. 242-251.
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© 2019 Elsevier B.V. There are very limited researches carried out to investigate the influence of saturation degrees, freezing-thawing, and curing times on geotechnical properties of lime concrete (LC) and lime-cement concrete (LCC) due to the capillary action and changes in groundwater table. Subsequently, the primary goal of this research is to investigate the influence of these parameters on mechanical properties of LC and LCC using unconfined compression tests, namely uniaxial compressive strength (UCS), stress-strain behavior, deformability index (I D ), secant modulus (E S ), failure strain, bulk modulus (K), resilient modulus (M R ), brittleness index (I B ), and shear modulus (G). At first, the mechanical and chemical characteristics of the utilized materials were measured. Then, samples were made with an optimal amount of cement, lime, coarse-grained soil, fine-grained soil, and water. The samples were then exposed to saturation points extending from 0 to 100% after 14, 28, 45 and 60 curing days. Then, to consider the effect of amount of saturation on the mechanical properties, UCS tests were performed on some of the samples. Other LCC specimens were exposed to freezing-thawing conditions to consider the effect of this phenomenon on the mechanical properties as well. The results of more than 250 UCS tests demonstrated that the curing times significantly affected the strength of LC and LCC specimens. Moreover, it is not ideal and logical to utilize LC and LC columns at a profundity underneath or near the groundwater level, though it is reasonable to adopt LCC and LCC columns at a profundity beneath or near the groundwater level because of the immaterial effect of degrees of saturation on LCC. In addition, this study showed that extending the curing period and diminishing the saturation degree would increase the strength and mechanical properties of the LCC specimens. The results of freezing-thawing demonstrated a negligible increase in the stre...
Jamaluddin, NAM, Riayatsyah, TMI, Silitonga, AS, Mofijur, M, Shamsuddin, AH, Ong, HC, Mahlia, TMI & Rahman, SMA 2019, 'Techno-Economic Analysis and Physicochemical Properties of Ceiba pentandra as Second-Generation Biodiesel Based on ASTM D6751 and EN 14214', Processes, vol. 7, no. 9, pp. 636-636.
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Processing biodiesel from non-edible sources of feedstock seems to be thriving in recent years. It also has also gathered more attention than in the past, mainly because the biodiesel product is renewable and emits lower pollution compared to fossil fuels. Researchers have started their work on various kinds of biodiesel product, especially from a non-edible feedstock. Non-edible feedstocks such as Ceiba pentandra show great potential in the production of biodiesel, especially in the Southeast Asia region because the plants seem to be abundant in that region. Ceiba pentandra, also known as the Kapok tree, produces hundreds of pods with a length of 15 cm (5.9 in) and diameter 2–5 cm (1–2 in). The pods consist of seeds and fluff in the surrounding areas inside the pod, which itself contains yellowish fibre, a mixture of cellulose and lignin. The seeds of Ceiba pentandra can be used as feedstock for biodiesel production. The study for Ceiba pentandra will involve techno-economic, as well as a sensitivity analysis. Moreover, the study also shows that the techno-economic analysis of a biodiesel processing plant for 50 ktons Ceiba pentandra with a life span of 20 years is around $701 million with 3.7 years of the payback period. Besides that, this study also shows the differences in operating cost and oil conversion yield, which has the least impact on running cost. By improving the conversion processes continuously and by increasing the operational efficiency, the cost of production will decrease. In addition, the study also explains the differences of final price biodiesel and diesel fossil fuel, both showing dissimilar scenarios subsidy and taxation. Biodiesel has a subsidy of $0.10/L and $0.18/L with a total tax exemption of 15%. The value was obtained from the latest subsidy cost and diesel in Malaysia. Finally, further research is needed in order to fully utilize the use of Ceiba pentandra as one of the non-edible sources of biodiesel.
Jamil, S, Loganathan, P, Kandasamy, J, Listowski, A, Khourshed, C, Naidu, R & Vigneswaran, S 2019, 'Removal of dissolved organic matter fractions from reverse osmosis concentrate: Comparing granular activated carbon and ion exchange resin adsorbents', Journal of Environmental Chemical Engineering, vol. 7, no. 3, pp. 103126-103126.
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© 2019 Elsevier Ltd. All rights reserved. Reverse osmosis (RO) generates a concentrate (ROC) containing dangerous levels of pollutants including dissolved organic carbon (DOC). Adsorption experiments were conducted to study the effectiveness of removing DOC and its fractions from ROCs produced in a water reclamation plant using three adsorbents tested individually and in sequential combination. The ROCs had 23-42 mg/L DOC which contained 83-90% hydrophilics. These hydrophilics comprised 72-76% humics, 2-3% biopolymers, 5-7% building blocks, and 16-18% low molecular weight neutrals. Granular activated carbon (GAC) removed a larger amount of DOC than two strong base anion exchange resins (Purolite A502PS, Purolite A860S). In both batch and column experiments, the adsorptive removal of the hydrophobic fraction was greater for GAC than for the Purolites. Humics present in hydrophilic fraction was completely removed by Purolites but only partially by GAC. In the sequential adsorption batch experiment, GAC followed by Purolite treatment removed more hydrophobics, however, Purolite followed by GAC removed more humics. Almost 100% of humics was removed for all doses of adsorbents when Purolite served as the first treatment. It is concluded that the order of adsorbent use for effectively treating ROC depends on the target DOC fraction intended to be removed.
Jamil, S, Loganathan, P, Listowski, A, Kandasamy, J, Khourshed, C & Vigneswaran, S 2019, 'Simultaneous removal of natural organic matter and micro-organic pollutants from reverse osmosis concentrate using granular activated carbon', Water Research, vol. 155, pp. 106-114.
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© 2019 Elsevier Ltd Although reverse osmosis produces high quality reusable water from wastewater the rejected concentrate (ROC) poses potentially serious health hazards to non-target species. This is especially the case when it is disposed into aquatic environments due to the presence of high concentrations of dissolved natural organics, micro-organic pollutants (MOPs) and other pollutants. In batch and column studies we found that granular activated carbon (GAC) was very effective in simultaneously removing dissolved organic carbon (DOC) and 18 MOPs from ROC. The amounts of all DOC fractions adsorbed (0.01–3 mg/g) were much higher than those of the MOPs (0.01–2.5 μg/g) mainly because ROC contained larger concentrations of DOC fractions than MOPs. However, the partition coefficient which is a measure of the adsorbability was higher for most of the MOPs (0.21–21.6 L/g) than for the DOC fractions (0.01–0.45 L/g). The amount of DOC fraction adsorbed was in the order: humics > low molecular weights > building blocks > biopolymers (following mostly their concentrations in ROC). The partition coefficient was in the order: low molecular weigth nuetrals > humics > building blocks > biopolymers. The MOPs were classified into four groups based on their hydrophobicity (log Kow) and charge. The four positively charged MOPs with high hydrophobicity had the highest amounts adsorbed and partition coefficient, with 95–100% removal in the GAC column. The MOPs that are negatively charged, regardless of their hydrophobicity, had the lowest amounts adsorbed and partition coefficient with 73–94% removal.
Jamilu Bala Ahmed, II, Pradhan, B, Mansor, S, Tongjura, JDC & Yusuf, B 2019, 'Multi-criteria evaluation of suitable sites for termite mounds construction in a tropical lowland', CATENA, vol. 178, pp. 359-371.
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© 2019 Elsevier B.V. Termite mounds influence ecosystem heterogeneity and contribute to the stabilization of the system under global change. A number of environmental factors influence the distribution, height, diameter and designs of termite mounds but these factors are not only poorly understood, they cannot be extrapolated for everywhere. In this study, we employed a ground based survey and Geographical Information System (GIS) technique to map 156 km 2 study area in Keffi, Nigeria. The aims were to (1) estimate the density and area covered by termite mounds, (2) sample and identify species types and how they are distributed, and (3) use five environmental factors (elevation, geology, surface water drainage, land use/land cover and static water level) to model suitable sites for mounds construction. A total of 361 mounds were mapped representing a density of about 0.8 mounds ha −1 and covering only about 0.31% of the studied area. Next, the effect of the five chosen environmental factors on the geographic distribution, life status, height and diameter of mounds and species diversity were analysed and their relationships plotted in pairwise comparison matrices using the Saaty's Analytical Hierarchy Process. Normalized rates for classes in each factor and corresponding weights were computed and aggregated using the Weighted Linear Combination method. The result depicted that moderate to low elevation (270–330 m amsl), rock cover types that are more susceptible to weathering (schist), cultivated areas and shallow water table zones are most favourable for termites to build mounds. The result obtained in this study shows a promising correlation between the environmental factors and termite mounds distribution. The proposed model can easily be replicated in a different but similar multi-land use and rock cover types.
Jamshaid, M, Masjuki, HH, Kalam, MA, Zulkifli, NWM, Arslan, A, Alwi, A, Khuong, LS, Alabdulkarem, A & Syahir, AZ 2019, 'Production optimization and tribological characteristics of cottonseed oil methyl ester', Journal of Cleaner Production, vol. 209, pp. 62-73.
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Jamshidi Chenari, R, Alaie, R & Fatahi, B 2019, 'Constrained Compression Models for Tire-Derived Aggregate-Sand Mixtures Using Enhanced Large Scale Oedometer Testing Apparatus', Geotechnical and Geological Engineering, vol. 37, no. 4, pp. 2591-2610.
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© 2018, Springer Nature Switzerland AG. Tire derived aggregates have recently been in wide use both in industry and engineering applications depending on the size and the application sought. Five different contents of tire derived aggregates (TDA) were mixed with sand thoroughly to ensure homogeneity. A series of large scale oedometer experiments were conducted to investigate the compressibility properties of the mixtures. Tire shreds content, TDA aspect ratio, skeletal relative density and overburden pressure are studied parameters. Constrained deformation modulus and coefficient of earth pressure at rest are measured parameters. All tests were conducted at seven overburden pressure levels. It was concluded that deformability of TDA-sand mixture increases with soft inclusion. Overburden pressure and skeletal relative density are also important parameters which render more rigidity and less lateral earth pressure coefficient accordingly. TDA size or aspect ratio was shown to have minor effect at least for the constrained strain conditions encountered in current study. An EPR-based parametric study and also sensitivity analyses based on cosine amplitude method revealed quantitative evaluation of the relative importance of each input parameter in varying deformation and lateral earth pressure coefficient as the outputs.
Javaheri, F, Kheshti, Z, Ghasemi, S & Altaee, A 2019, 'Enhancement of Cd2+ removal from aqueous solution by multifunctional mesoporous silica: Equilibrium isotherms and kinetics study', Separation and Purification Technology, vol. 224, pp. 199-208.
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© 2019 In this work, a novel amino-functionalized mesoporous microsphere was synthesized to remove cadmium ions from water. The Fe3O4@SiO2@m-SiO2–NH2 micro-spheres were successfully prepared via a facile two-stage process by coating of the as-synthesized magnetic cores with a silica shell followed by increasing the porosity of the structure using a cationic surfactant as structure-directing agents. The template removal from the structure has been performed following the method of solvent extraction and methanol-enhanced supercritical fluid CO2 (SCF-CO2)extraction. This novel approach provides the multifunctional microspheres with a high surface area, which improves the adsorption capacity of adsorbent. Characterization of the as-synthesized adsorbent were analytically determined showing that as-prepared adsorbent has a significant surface area of 637.38 m2 g−1. The kinetic data agreed with pseudo-second-order model and Langmuir isotherm. The maximum adsorption capacity of the synthesized adsorbent was about 884.9 mg g−1, and can be easily separated from solution under an external magnetic field. The synthesized microspheres were recycled using HCl and cadmium removal was over 92% after 6 cycles, which confirms the chemical stability and reusability of the manufactured particles.
Javdanian, H & Pradhan, B 2019, 'Assessment of earthquake-induced slope deformation of earth dams using soft computing techniques', Landslides, vol. 16, no. 1, pp. 91-103.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Evaluating behavior of earth dams under dynamic loads is one of the most important problems associated with the initial design of such massive structures. This study focuses on prediction of deformation of earth dams due to earthquake shaking. A total number of 103 real cases of deformation in earth dams due to earthquakes that has occurred over the past years were gathered and analyzed. Using soft computing methods, including feed-forward back-propagation and radial basis function based neural networks, two models were developed to predict slope deformations in earth dams under variant earthquake shaking. Earthquake magnitude (Mw), yield acceleration ratio (ay/amax), and fundamental period ratio (Td/Tp) were considered as the most important factors contributing to the level of deformation in earth dams. Subsequently, a sensitivity analysis was conducted to assess the performance of the proposed model under various conditions. Finally, the accuracy of the developed soft computing model was compared with the conventional relationships and models to estimate seismic deformations of earth dams. The results demonstrate that the developed neural model can provide accurate predictions in comparison to the available practical charts and recommendations.
Jayasuriya, C, Indraratna, B & Ngoc Ngo, T 2019, 'Experimental study to examine the role of under sleeper pads for improved performance of ballast under cyclic loading', Transportation Geotechnics, vol. 19, pp. 61-73.
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© 2019 Elsevier Ltd The degradation and deformation of ballast critically affect the track geometry, safety, and passenger comfort. The increase in axle loads and train speed increases the stress applied on the ballast and exacerbates the rate of ballast degradation. This situation is more critical when tracks are built on stiff subgrades (e.g. bridges, tunnels and crossings), hence the use of energy absorbing (damping) layers in track substructure is a countermeasure to minimize track damage. In this study, a series of large-scale laboratory tests using the track process simulation testing apparatus (TPSA) is carried out to assess the performance of under sleeper pads (USP) to reduce ballast degradation and to decrease permanent deformation. When placed beneath the sleeper, the energy absorbing nature of USP reduces the energy transferred to the ballast and other substructure components. Subsequently, the ballast layer experiences less deformation and degradation. Innovative tactile surface sensors (matrix-based) are used to measure the pressure and contact area between sleeper and ballast. The measured data show that an increase in contact area between sleeper and ballast decreases the stress applied on ballast, and thus a reduction in ballast breakage and corresponding reduced ballast deformation can be achieved. Furthermore, the influence of the USP stiffness is examined and the measured data offer an insightful understanding of the role of USP for given track and loading conditions in terms of energy dissipation and reduced ballast deformation.
Jayawardana, D, Liyanapathirana, R & Zhu, X 2019, 'RFID-Based Wireless Multi-Sensory System for Simultaneous Dynamic Acceleration and Strain Measurements of Civil Infrastructure', IEEE Sensors Journal, vol. 19, no. 24, pp. 12389-12397.
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© 2001-2012 IEEE. In this paper, we develop a radio frequency identification (RFID)-based wireless multi-sensory infrastructure health monitoring (IHM) system that can simultaneously measure dynamic acceleration and strain. The system consists of a novel multi-sensor integrated semi-passive ultra-high frequency (UHF) tag antenna that can be mounted on civil infrastructure elements; even made out of metal. The system is capable of measuring 3-axis dynamic acceleration and strain with spectral bandwidths of 40 Hz and 26.5 Hz, respectively. The natural frequency determination of infrastructure by the dynamic acceleration and strain measurements of the proposed system is accurate to 60 mHz. Benchmarking of the RFID-based wireless multi-sensory system is provided by comprehensive comparison of the results with measurements from a commercial wireless strain measurement system. The proposed system has 30 mHz natural frequency determination error when compared with dynamic strain measurement from the commercial system.
Jeevanantham, AK, Nanthagopal, K, Ashok, B, Al-Muhtaseb, AH, Thiyagarajan, S, Geo, VE, Ong, HC & Samuel, KJ 2019, 'Impact of addition of two ether additives with high speed diesel- Calophyllum Inophyllum biodiesel blends on NOx reduction in CI engine', Energy, vol. 185, pp. 39-54.
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Jeong, SY, Chang, SW, Ngo, HH, Guo, W, Nghiem, LD, Banu, JR, Jeon, B-H & Nguyen, DD 2019, 'Influence of thermal hydrolysis pretreatment on physicochemical properties and anaerobic biodegradability of waste activated sludge with different solids content', Waste Management, vol. 85, pp. 214-221.
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© 2018 Elsevier Ltd The influence of thermal hydrolysis pretreatment (THP) on physicochemical properties (pH, total solids, volatile solids, chemical oxygen demand, total nitrogen, ammonium nitrogen, volatile fatty acids, viscosity, and cell morphology) and anaerobic biodegradability of highly concentrated waste activated sludge (WAS) with TS content ranging from 1 to 7% was evaluated at different temperatures ranging from 100 to 220 °C. The biomethane potential (BMP) of the WAS was systematically analyzed and evaluated. Images of its cellular structure were also analyzed. The results indicated that THP is a useful method for solubilizing volatile solids and enhancing CH 4 production regardless of the TS content of the WAS feed. The ultimate CH 4 production determined from the BMP analysis was 313–348 L CH 4 /kg VS (72.6–74.1% CH 4 ) at the optimum THP temperature of 180 °C. The results showed that THP could improve both the capacity and efficiency of anaerobic digestion, even at a high TS content, and could achieve the dual purpose of sludge reduction and higher energy recovery.
Jia, H, Feng, F, Wang, J, Ngo, H-H, Guo, W & Zhang, H 2019, 'On line monitoring local fouling behavior of membrane filtration process by in situ hydrodynamic and electrical measurements', Journal of Membrane Science, vol. 589, pp. 117245-117245.
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© 2019 The hollow fiber ultrafiltration (UF) membrane has been widely applied in the water treatment industry, however, the membrane fouling is the core reason and limiting factor in terms of its industrial application. In the constant flux process, hollow fiber membranes (HFM) non-uniform fouling varies along the axis direction, which is the basic mechanism of HFM fouling. In this paper, the local membrane fouling behaviors and verities are investigated using electrical impedance (EI) and zeta potential (ZP) to capture the feedback signals of membrane fouling behaviors. The results are then, integrated with Hermia's model and an equivalent circuit model. As the fitting results show, both the EI and ZP can be employed as indicators of different membrane fouling states. This work defines the different stages of membrane fouling depending on the alternating relationship between EI and ZP in the membrane filtration process. Furthermore, the behavior of cake layer compaction is defined from the perspective of the membrane fouling mechanism. Therefore, this study provides an effective means for accurate identification of membrane fouling behavior. In addition, the EI and ZP exhibit great potential to identify the fouling distributions and proceedings in HFM fouling. Doing so successfully confirms that the characteristics of non-uniform fouling of HFM are reflected in the spatiotemporal difference of the fouling process.
Jia, Y, Tang, L, Xu, B & Zhang, S 2019, 'Crack Detection in Concrete Parts Using Vibrothermography', Journal of Nondestructive Evaluation, vol. 38, no. 1.
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Jiang, J, Kim, DI, Dorji, P, Phuntsho, S, Hong, S & Shon, HK 2019, 'Phosphorus removal mechanisms from domestic wastewater by membrane capacitive deionization and system optimization for enhanced phosphate removal', Process Safety and Environmental Protection, vol. 126, pp. 44-52.
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© 2019 Institution of Chemical Engineers Membrane capacitive deionization (MCDI) is an emerging technology for effective removal of charged pollutants from the water sources including domestic wastewater. In this work, a lab-scale MCDI system was employed to investigate its feasibility for effective phosphorus removal from domestic wastewater. The effect of phosphate equilibrium reactions on the ion sorption behaviour was studied in sodium phosphate buffer solution at typical pH range maintained in a real domestic raw wastewater effluent (between 6.5 and 8.5). The results demonstrated that phosphate equilibrium system has positive impact on the degree of inorganic phosphorus (P) adsorption capacity in aqueous solution. In addition, the ion selectivity of P over other co-existing anions (Cl-, SO42-) were experimentally studied using a synthetic wastewater solution. And it was found that the preferential electrosorption sequence of the competitive anions is: Cl-> SO42- > P, while the initial ion concentration order in the synthetic feed solution is: Cl- 1.90 mM> P (0.40 mM) > SO42- (0.32 mM). The experiments with diverse operating conditions revealed that the optimal adsorption of inorganic phosphorus over chloride and sulphate can be achieved in some extent with slower flow rates and higher applied potentials (less than 1.23 V).
Jiang, Y & Nimbalkar, S 2019, 'Finite Element Modeling of Ballasted Rail Track Capturing Effects of Geosynthetic Inclusions', Frontiers in Built Environment, vol. 5.
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© 2019 Jiang and Nimbalkar. This paper presents a two dimensional finite element (FE) approach to investigating beneficial aspects of geogrids in the railway track. The influences of different factors including the subgrade strength, the geogrid stiffness, the placement depth of geogrid, the effective width of geogrid, the strength of ballast-geogrid interface and the combination of double geogrid layers were investigated under the monotonic loading. The results indicated the role of geogrid reinforcement is more pronounced over the weak compressible subgrade. A stiffer geogrid reduces ballast settlement and produces a more uniform stress distribution along a track. The placement location of a geogrid is suggested at the ballast-sub-ballast interface to achieve better reinforcement results. Although the width of a geogrid layer should be sufficient to cover an entire loaded area, excessive width does not guarantee additional benefits. Higher interface strength between a ballast and a geogrid is beneficial for effective reinforcement. Increasing the number of geogrid layers is an effective way to reinforce the ballast over weak subgrades. The results of the limited cyclic FE simulations revealed the consistency of the reinforcement effect of the geogrids under monotonic and cyclic loads.
Jo, Y, Johir, MAH, Cho, Y, Naidu, G, Rice, SA, McDougald, D, Kandasamy, J, Vigneswaran, S & Sun, S 2019, 'A comparative study on nitric oxide and hypochlorite as a membrane cleaning agent to minimise biofilm growth in a membrane bioreactor (MBR) process', Biochemical Engineering Journal, vol. 148, pp. 9-15.
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© 2019 Elsevier B.V. Reverse osmosis concentrates (ROC) produced from water reclamation plants can threaten the environment if it is not appropriately treated before discharge. A membrane bioreactor (MBR) process to treat ROC was used in this project. In an MBR, fouling is an essential and inevitable phenomenon which leads to higher operational and capital costs. A comparative study on chemical cleaning, such as sodium hypochlorite (NaOCl) and nitric oxide (NO), was experimentally evaluated together with the influence of filtration flux. Exposure to a low concentration of NO reduced biofilms in an MBR system. NO treatment delayed the formation of new biofilm biomass on the membrane. NO also showed good performance in reducing membrane fouling and had no adverse effect on activated sludge and the environment. In MBR, the bacterial community was dominated by Proteobacteria (61%), with Alpha and Beta-proteobacteria representing approximately 54% of the community. After NO treatment, the relative abundance of the Proteobacteria decreased to 44%, and this was also reflected in a reduction in Alpha and Beta-proteobacteria, to 30% and 5% respectively. Thus, NO treatment resulted in the decrease of the relative biofilms associated with reduced MBR performance.
Kalantar, Al-Najjar, Pradhan, Saeidi, Halin, Ueda & Naghibi 2019, 'Optimized Conditioning Factors Using Machine Learning Techniques for Groundwater Potential Mapping', Water, vol. 11, no. 9, pp. 1909-1909.
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Assessment of the most appropriate groundwater conditioning factors (GCFs) is essential when performing analyses for groundwater potential mapping. For this reason, in this work, we look at three statistical factor analysis methods—Variance Inflation Factor (VIF), Chi-Square Factor Optimization, and Gini Importance—to measure the significance of GCFs. From a total of 15 frequently used GCFs, 11 most effective ones (i.e., altitude, slope angle, plan curvature, profile curvature, topographic wetness index, distance from river, distance from fault, river density, fault density, land use, and lithology) were finally selected. In addition, 917 spring locations were identified and used to train and test three machine learning algorithms, namely Mixture Discriminant Analysis (MDA), Linear Discriminant Analysis (LDA) and Random Forest (RF). The resultant trained models were then applied for groundwater potential prediction and mapping in the Haraz basin of Mazandaran province, Iran. MDA has been successfully applied for soil erosion and landslide mapping, but has not yet been fully explored for groundwater potential mapping (GPM). Although other discriminant methods, such as LDA, exist, MDA is worth exploring due to its capability to model multivariate nonlinear relationships between variables; it also undertakes a mixture of unobserved subclasses with regularization of non-linear decision boundaries, which could potentially provide more accurate classification. For the validation, areas under Receiver Operating Characteristics (ROC) curves (AUC) were calculated for the three algorithms. RF performed better with AUC value of 84.4%, while MDA and LDA yielded 75.2% and 74.9%, respectively. Although MDA performance is lower than RF, the result is satisfactory, because it is within the acceptable standard of environmental modeling. The outcome of factor analysis and groundwater maps emphasizes on optimization of multicolinearity factors for faster spatial m...
Kalaruban, M, Loganathan, P, Nguyen, TV, Nur, T, Hasan Johir, MA, Nguyen, TH, Trinh, MV & Vigneswaran, S 2019, 'Iron-impregnated granular activated carbon for arsenic removal: Application to practical column filters', Journal of Environmental Management, vol. 239, pp. 235-243.
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© 2019 Elsevier Ltd Arsenic is a major drinking water contaminant in many countries causing serious health hazards, and therefore, attempts are being made to remove it so that people have safe drinking water supplies. The effectiveness of arsenic removal from As(V) solutions using granular activated carbon (GAC) (zero point of charge (ZPC) pH 3.2) and iron incorporated GAC (GAC-Fe) (ZPC pH 8.0) was studied at 25 ± 1 °C. The batch study confirmed that GAC-Fe had higher Langmuir adsorption capacity at pH 6 (1.43 mg As/g) than GAC (1.01 mg As/g). Adsorption data of GAC-Fe fitted the Freundlich model better than the Langmuir model, thus indicating the presence of heterogeneous adsorption sites. Weber and Morris plots of the kinetic adsorption data suggested intra-particle diffusion into meso and micro pores in GAC. The column adsorption study revealed that 2–4 times larger water volumes can be treated by GAC-Fe than GAC, reducing the arsenic concentration from 100 μg/L to the WHO guideline of 10 μg/L. The volume of water treated increased with a decrease in flow velocity and influent arsenic concentration. The study indicates the high potential of GAC-Fe to remove arsenic from contaminated drinking waters in practical column filters.
Kang, Y, Xie, H, Li, B, Zhang, J, Hao Ngo, H, Guo, W, Guo, Z, Kong, Q, Liang, S, Liu, J, Cheng, T & Zhang, L 2019, 'Performance of constructed wetlands and associated mechanisms of PAHs removal with mussels', Chemical Engineering Journal, vol. 357, pp. 280-287.
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Karthickeyan, V, Thiyagarajan, S, Geo, VE, Ashok, B, Nanthagopal, K, Chyuan, OH & Vignesh, R 2019, 'Simultaneous reduction of NOx and smoke emissions with low viscous biofuel in low heat rejection engine using selective catalytic reduction technique', Fuel, vol. 255, pp. 115854-115854.
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© 2019 Elsevier Ltd The present work offered a comprehensive investigation on engine characteristics of single cylinder Direct Injection (DI) diesel engine fuelled with Lemon oil (LO) biofuel. LO was obtained from the peels of lemon using steam distillation process. The physio-chemical properties of LO were analysed based ASTM biodiesel standard and compared with diesel. The chemical composition of LO was observed with Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography and Mass Spectrometry (GC–MS). In-order to enhance the properties of LO, a cetane enhancer namely Pyrogallol (PY) was added. The engine combustion chamber components namely piston head, cylinder head and intake and exhaust valves were thermally coated with Partially Stabilized Zirconia (PSZ) which converted the conventional engine into low heat rejection engine. In the PSZ coated engine, enhanced performance and combustion characteristics were observed with LO and PY blend. Declined carbon monoxide (CO), hydrocarbon (HC) and smoke emissions were observed with LO and PY blend in coated engine. Further, the work was extended with the application of Selective catalytic reduction (SCR) and Catalytic Converter (CC) as post treatment system for the reduction of NOx emission. With post treatment, LO and pyrogallol in PSZ coated engine showed lower NOx emission than diesel and LO. Consequently, LO and pyrogallol in PSZ coated engine with post treatment was considered as more advantageous than other fuel samples on account of its performance, combustion and emission characteristics.
Keith, A, Brown, NJ & Zhou, JL 2019, 'The feasibility of a collapsible parabolic solar cooker incorporating phase change materials', Renewable Energy Focus, vol. 30, pp. 58-70.
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© 2019 Elsevier Ltd This paper presents a solar energy-based cooking solution for reducing the dependency of refugees on firewood for cooking food. The use of firewood is associated with a variety of problems such as deforestation, environmental degradation and household air pollution. This paper proposes that a collapsible parabolic solar cooker with 12 panels and a phase change material-incorporated cooking pot is a viable alternative to firewood. The phase change material allows food cooked during the day to be kept warm and subsequently consumed as an evening meal. Furthermore, the proposed solution considers, and fits within, the cultural aspect of the refugee context. The cultural aspect is highlighted as it is a factor in determining whether refugees will accept the proposed solution. This paper also presents a cost-benefit analysis of the proposed solution which shows that if used by a family unit of four members, the payback period is 52 weeks or less. Finally, this paper concludes with recommendations pertaining to the efficiency of the system to reduce cooking time and enable the system to keep food warm for subsequent meals. These recommendations are focused on maximising the chances of acceptance of the parabolic solar cooker by refugees during humanitarian crises.
Khabbaz, H, Gibson, R & Fatahi, B 2019, 'Effect of constructing twin tunnels under a building supported by pile foundations in the Sydney central business district', Underground Space, vol. 4, no. 4, pp. 261-276.
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© 2019 Tongji University and Tongji University Press In congested cities such as Sydney, competition for underground space escalates within the built environment because various assets require finite geotechnical strength and support. Specific problems such as damage to buildings may develop when high-rise buildings on piled foundations are subject to ground movements as tunnels are constructed. This paper focuses on the risks of tunneling beneath Sydney's Martin Place and how buildings are subject to additional loads caused by tunneling. The key objective of this study is to improve the understanding of tunnel–rock–pile interactions and to encourage sustainable development. A finite element model is developed to predict the interaction between tunnel construction and piled foundations. The tunnel, rock, and pile components are studied separately and are then combined into a single model. The ground model is based on the characteristics of Hawkesbury Sandstone and is developed through a desktop study. The piles are designed using Australian Standards and observations of high-rise buildings. The tunnel construction is modeled based on the construction sequence of a tunnel boring machine. After combining the components, a parametric study on the relationship between tunnel location, basements, and piles is conducted. Our findings, thus far, show that tunneling can increase the axial and flexural loads of piles, where the additional loading exceeds the structural capacity of some piles, especially those that are close to basement walls. The parametric study reveals a strong relationship between tunnel depth and lining stresses, while the relationship between tunnel depth and induced pile loads is less convincing. Furthermore, the horizontal tunnel position relative to piles shows a stronger relationship with pile loads. Further research into tunnel–rock–pile interactions is recommended, especially beneath basements, to substantiate the results of this study.
Khan, HA, Castel, A, Khan, MSH & Mahmood, AH 2019, 'Durability of calcium aluminate and sulphate resistant Portland cement based mortars in aggressive sewer environment and sulphuric acid', Cement and Concrete Research, vol. 124, pp. 105852-105852.
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© 2019 Elsevier Ltd This study aims to compare the performance of sulphate resisting (SR) Portland cement mortar (SRm) and calcium aluminate cement mortars (CACm) in both natural sewer environment and sulphuric acid. Specimens were extracted after 12 and 24 months from field exposure, and were also removed from 1.5% sulphuric acid (H2SO4) after 6 months to investigate the deterioration caused by chemically induced corrosion. Visual, physical and extensive microstructural analyses were performed to evaluate the degradation of CACm and SRm matrix using techniques such as Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX), X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) Spectroscopy. Surface pH was estimated after 12 and 24 months of field exposure to identify the initiation of biotic film development due to microbial induced corrosion (MIC). Material properties such as mass loss, compressive strength, linear expansion, and pH profile with respect to neutralization depth were also measured. The difference in mechanism of deterioration was also highlighted based on microstructural investigations between in field experimentation and acid exposure. The results showed that overall CACm performed significantly better than SRm in onsite sewer environment and sulphuric acid solution in terms of visual observations, loss in mass, compressive strength reduction, depth of neutralization, reduction in pH and penetration of sulphur. Crystallization of gypsum within the matrix of both mixes was the main factor behind the deterioration observed using XRD and FTIR from both in field and acid attack exposure, with higher deterioration within the matrix of SRm as compared to CACm. Moreover, sulphuric acid testing is suitable for screening the mixes rapidly against acidic environment, but due to the major differences observed in deterioration processes with natural field conditions this method is unsuitable for service life design of sewage structures.
Khan, I, Xu, T, Castel, A & Gilbert, RI 2019, 'Early-age tensile creep and shrinkage-induced cracking in internally restrained concrete members', Magazine of Concrete Research, vol. 71, no. 22, pp. 1167-1179.
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Experiments were carried out under ambient conditions and in a temperature–humidity control room to assess the influences of early-age shrinkage and tensile creep on cracking in reinforced-concrete (RC) members subjected to internal restraint. Two concrete mixes were considered, with compressive strengths of 36 MPa and 47 MPa. The evolution of the tensile creep coefficients was measured using unreinforced dog-bone-shaped specimens subjected to sustained axial tension. The shrinkage-induced stress tests were performed on RC prisms internally restrained by one concentrically placed reinforcement. Free shrinkage and restrained shrinkage were measured on companion plain concrete prisms and on unloaded RC prisms, respectively, to determine the degree of restraint. The results show that the 36 MPa concrete had a higher tensile creep coefficient than the 47 MPa concrete, but that there were no significant differences in early-age free shrinkage. A lower humidity results in more free shrinkage strain, but leads to more tensile creep and, consequently, increased relaxation of the tensile stresses. The magnitude of the restrained shrinkage depends on the reinforcement ratio. The development of the tensile strength of concrete is a governing factor influencing the time to cracking. The tensile ageing coefficient was calibrated for the two concrete mixes.
Khan, I, Xu, T, Castel, A, Gilbert, RI & Babaee, M 2019, 'Risk of early age cracking in geopolymer concrete due to restrained shrinkage', Construction and Building Materials, vol. 229, pp. 116840-116840.
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© 2019 Elsevier Ltd In this paper, experimental tests were carried out in order to measure early-age shrinkage and tensile creep of geopolymer concrete and assess their influence on early age cracking in reinforced concrete members. Two mixes of geopolymer concrete were tested. For the first mix, the specimens were heat-cured at a temperature of either 60 °C or 90 °C. For the second mix, the specimens were cured under ambient conditions. Tensile creep was directly measured using unreinforced dog-bone shaped specimens subjected to sustained axial tension. The shrinkage induced stress tests were performed on restrained geopolymer concrete rings. The results show that the tensile creep coefficient and shrinkage strains in geopolymer concrete are affected by the curing temperature and duration. Higher curing temperature leads to less tensile creep and shrinkage strains. Heat-cured geopolymer concrete demonstrated a lower early-age shrinkage and higher tensile creep coefficient, compared to the control ordinary Portland cement (OPC) concrete. Both restrained ring test and simulations confirm that heat-cured geopolymer concrete can relax undesirable stresses in concrete caused by restrained shrinkage, and reduce the risk of early-age cracking.
Khan, JA, Shon, HK & Nghiem, LD 2019, 'From the Laboratory to Full-Scale Applications of Forward Osmosis: Research Challenges and Opportunities', Current Pollution Reports, vol. 5, no. 4, pp. 337-352.
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© 2019, Springer Nature Switzerland AG. Forward osmosis (FO) has recently emerged as a new separation platform for a range of applications that are currently not possible for other membrane processes. This review paper covers key aspects of FO development with a specific emphasis on current technical challenges for practical applications. Main hurdles in the transition of FO from a lab-scale process to large scale applications include low-performance membranes, development of suitable draw solute, inherent transport phenomena (e.g. concentration polarization and reverse solute flux), membrane fouling and subsequent membrane cleaning. Several new FO membranes have been developed with some improved performances but no membrane has yet been found convincing in all of the key performance indicators. Draw solutes have been broadly investigated but mainly at the lab-scale. There have only been very few pilot-scale studies, most of them using inorganic salts as draw solutes. Development of thermo-responsive draw solutes and TFC membranes have been reported to be most effective in reducing reverse solute flux while altering the hydrodynamic conditions and the use of ultrasonication along with exploring other viable options have been suggested to tackle external and internal concentration polarization respectively. Although membrane fouling types and mitigation strategies have been extensively explored, this review also highlights the need for further research in biofouling for long-term FO operation.
Khan, MA, Ngo, HH, Guo, W, Chang, SW, Nguyen, DD, Varjani, S, Liu, Y, Deng, L & Cheng, C 2019, 'Selective production of volatile fatty acids at different pH in an anaerobic membrane bioreactor', Bioresource Technology, vol. 283, pp. 120-128.
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© 2019 Elsevier Ltd This study investigated the production of major volatile fatty acid (VFA) components in an anaerobic membrane bioreactor (AnMBR) to treat low-strength synthetic wastewater. No selective inhibition was applied for methane production and solvent-extraction method was used for VFA extraction. The results showed acetic and propionic acid were the predominant VFA components at pH 7.0 and 6.0 with concentrations of 1.444 ± 0.051 and 0.516 ± 0.032 mili-mol/l respectively. At pH 12.0 isobutyric acid was the major VFA component with a highest concentration of 0.712 ± 0.008 mili-mol/l. The highest VFA yield was 48.74 ± 1.5 mg VFA/100 mg CODfeed at pH 7.0. At different pH, AnMBR performance was evaluated in terms of COD, nutrient removal and membrane fouling rate. It was observed that the membrane fouled at a faster rate in both acidic and alkaline pH conditions, the slowest rate in membrane fouling was observed at pH 7.0.
Khan, MA, Ngo, HH, Guo, W, Liu, Y, Nghiem, LD, Chang, SW, Nguyen, DD, Zhang, S, Luo, G & Jia, H 2019, 'Optimization of hydraulic retention time and organic loading rate for volatile fatty acid production from low strength wastewater in an anaerobic membrane bioreactor', Bioresource Technology, vol. 271, pp. 100-108.
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This study aims to investigate the production of volatile fatty acids (VFAs) from low strength wastewater at various hydraulic retention time (HRT) and organic loading rate (OLR) in a continuous anaerobic membrane bioreactor (AnMBR) using glucose as carbon source. This experiment was performed without any selective inhibition of methanogens and the reactor pH was maintained at 7.0 ± 0.1. 48, 24, 18, 12, 8 and 6 h-HRTs were applied and the highest VFA concentration was recorded at 8 h with an overall VFA yield of 48.20 ± 1.21 mg VFA/100 mg CODfeed. Three different ORLs were applied (350, 550 and 715 mg CODfeed) at the optimum 8 h-HRT. The acetic and propanoic acid concentration maximums were (1.1845 ± 0.0165 and 0.5160 ± 0.0141 mili-mole/l respectively) at 550 mg CODfeed. The isobutyric acid concentration was highest (0.3580 ± 0.0407 mili-mole/l) at 715 mg CODfeed indicating butyric-type fermentation at higher organic loading rate.
Kheshti, Z, Azodi Ghajar, K, Altaee, A & Kheshti, MR 2019, 'High-Gradient Magnetic Separator (HGMS) combined with adsorption for nitrate removal from aqueous solution', Separation and Purification Technology, vol. 212, pp. 650-659.
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© 2018 Elsevier B.V. This paper investigates the adsorption of nitrate anions from aqueous solutions on ammonium-functionalized magnetic mesoporous silica. The adsorbent was prepared via two-step coating process of silica on magnetic core (Fe3O4). The resultant structure was modified by 3-aminopropyl triethoxysilane (APTES), and finally acidified in HCl solution to convert the grafted amino groups to ammonium ones. Field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), vibration sample magnetometer (VSM), Energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and N2 adsorption/desorption were used to characterize the obtained samples. Experimental results showed that several factors affected the uptake behavior such as pH, contact time, and initial concentration of nitrate. The amount of sorbent loading were examined and the adsorbent shows great adsorption capacity for NO3¯ (ca.51.28 mg g−1 at 25 °C). The nitrate loaded multifunctional microsphere can be easily regenerated with NaOH solution. The separation of multifunctional magnetic microspheres from solution by novel high gradient magnetic separation (HGMS), using the collection of rods, was also investigated in details. Contrast to other methods based on filter and batch conditions, large volumes of water can be easily handled by the new designed HGMS due to the decreasing pressure drop and retention times. The effect of a set of two different experimental variables, i.e. flowrate and magnetic field strength, were investigated to identify the best working conditions for the separation of adsorbent from treated water. The most efficient backwash system was offered to reuse the magnetic particles, too. The removal efficiency of NO3¯ from solution was around 86.24% by the constructed HGMS under the optimal experimental conditions of 7.5 mL s −1 flowrate and: 3.49 mT magnitude of the magnetic field.
Khosravi, K, Shahabi, H, Pham, BT, Adamowski, J, Shirzadi, A, Pradhan, B, Dou, J, Ly, H-B, Gróf, G, Ho, HL, Hong, H, Chapi, K & Prakash, I 2019, 'A comparative assessment of flood susceptibility modeling using Multi-Criteria Decision-Making Analysis and Machine Learning Methods', Journal of Hydrology, vol. 573, pp. 311-323.
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© 2019 Elsevier B.V. Floods around the world are having devastating effects on human life and property. In this paper, three Multi-Criteria Decision-Making (MCDM) analysis techniques (VIKOR, TOPSIS and SAW), along with two machine learning methods (NBT and NB), were tested for their ability to model flood susceptibility in one of China's most flood-prone areas, the Ningdu Catchment. Twelve flood conditioning factors were used as input parameters: Normalized Difference Vegetation Index (NDVI), lithology, land use, distance from river, curvature, altitude, Stream Transport Index (STI), Topographic Wetness Index (TWI), Stream Power Index (SPI), soil type, slope and rainfall. The predictive capacity of the models was evaluated and validated using the Area Under the Receiver Operating Characteristic curve (AUC). While all models showed a strong flood prediction capability (AUC > 0.95), the NBT model performed best (AUC = 0.98), suggesting that, among the models studied, the NBT model is a promising tool for the assessment of flood-prone areas and can allow for proper planning and management of flood hazards.
Kildashti, K, Samali, B, Mortazavi, M, Ronagh, H & Sharafi, P 2019, 'Seismic collapse assessment of a hybrid cold-formed hot-rolled steel building', Journal of Constructional Steel Research, vol. 155, pp. 504-516.
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This paper investigates seismic collapse potential of a hybrid cold-formed hot-rolled system in order to quantify the response modification factor (R-factor) through a procedural method proposed in FEMA-P695. A series of hot-rolled steel (HRS) knee-braced frames in conjunction with cold-formed steel (CFS) stud walls are proposed to resist lateral and gravity loads. ASCE7-16 does not provide seismic performance factors for this hybrid HRS/CFS structural topology in lightweight steel construction and as a result, more sophisticated assessment is needed to measure reasonable seismic performance. A nonlinear numerical model that simulates post-peak response of HRS knee-braced frames is calibrated with experimental data. Post-buckling behaviour of CFS studs are measured according to various techniques in terms of finite strip method (FSM), finite element method (FEM) and AISI-S136-16 analytical formulations. The modelling approach is implemented into nonlinear analytical models of a six-storey steel building which is designed in accordance with ASCE7-16, ANSI/AISC360-16, and AISI-S316-16. A suite of twenty-two bidirectional far-field ground motions are chosen from PEER/NGA database subset and scaled to conditional mean spectrum (CMS) relevant to Urban California region. A set of nonlinear static analysis as well as incremental dynamic analysis (IDA) is conducted to measure collapse fragility and seismic performance of the building. It is concluded that initially assumed R-factor for the proposed structural system maintains the collapse prevention criterion as recommended by FEMA-P695 and is appropriate to be considered for design purposes.
Kim, B-J, Piao, G, Kim, S, Yang, SY, Park, Y, Han, DS, Shon, HK, Hoffmann, MR & Park, H 2019, 'High-Efficiency Solar Desalination Accompanying Electrocatalytic Conversions of Desalted Chloride and Captured Carbon Dioxide', ACS Sustainable Chemistry & Engineering, vol. 7, no. 18, pp. 15320-15328.
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Kim, DI, Dorji, P, Gwak, G, Phuntsho, S, Hong, S & Shon, H 2019, 'Effect of Brine Water on Discharge of Cations in Membrane Capacitive Deionization and Its Implications on Nitrogen Recovery from Wastewater', ACS Sustainable Chemistry & Engineering, vol. 7, no. 13, pp. 11474-11484.
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© 2019 American Chemical Society. We examined the desorption behavior of cations in membrane capacitive deionization (MCDI) from the cathode into high-concentration brine through a cation-exchange membrane (CEM) brine, during mineral recovery. Several major issues were explored to demonstrate the suitability of the mineral recovery process: discharge behavior using different solution chemistries, desorption efficiencies of various regeneration methods for the enrichment of ions, and desorption selectivity among selected cations. The desorption efficiency was hampered when the adsorbed cations migrated toward the brine solution against a higher ionic-strength gradient and was further lowered by the enhanced membrane resistance under the low concentration of the adsorbed ions on the cathode. Furthermore, the electrochemically adsorbed ions were limitedly discharged by the cost-effective regeneration method (short-circuiting). The cations were preferentially released in the order of K+ > Na+ > Mg2+, as mainly determined by their physiochemical properties such as diffusion rate and charge valence, whereas the influence of permselectivity through the CEM was insignificant. Furthermore, through the ammonium recovery tests, a high concentration of ammonium brine was obtained from wastewater through a successive five-cycle-operation due to its selective desorption over the sodium ions present. However, the incomplete discharge of ions from the electrode was a challenging issue to overcome for the use of MCDI for ammonium recovery.
Kim, DI, Dorji, P, Gwak, G, Phuntsho, S, Hong, S & Shon, H 2019, 'Reuse of municipal wastewater via membrane capacitive deionization using ion-selective polymer-coated carbon electrodes in pilot-scale', Chemical Engineering Journal, vol. 372, pp. 241-250.
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© 2019 Elsevier B.V. This study investigated membrane capacitive deionization (MCDI) at a pilot-scale using ion-selective polymer-coated carbon electrodes for wastewater reuse. Several issues have been addressed to verify the suitability of MCDI for wastewater reclamation: electrosorption performance, removal efficiency and selectivity of ions present in wastewater, optimization of operating conditions, and performance degradation in long-term caused by the accumulation of organic contaminants. The coated electrodes had better adsorption capacities and charge efficiencies than the conventional MCDI system, which was attributed to their low electrical resistance induced by the thin coated layer. The pilot-scale MCDI test cell involved 50 pairs of anion- and cation-selective electrodes and achieved good removal efficiency of ions from the wastewater effluent, particularly for problematic charged impurities, such as nitrate (NO3−) (up to 91.08% of NO3− was removed). Increasing the flow rate and reducing the applied potential were shown to be efficient for achieving better water quality by enhancing the NO3− selectivity. Last, the 15 d operation showed good reproducibility in electrosorption and regeneration for the coated electrodes, despite the fact that high concentrations of organics were contained in the wastewater feed solution (12.4 mg/L of dissolved organic carbon).
Kim, JE, Kuntz, J, Jang, A, Kim, IS, Choi, JY, Phuntsho, S & Shon, HK 2019, 'Techno-economic assessment of fertiliser drawn forward osmosis process for greenwall plants from urban wastewater', Process Safety and Environmental Protection, vol. 127, pp. 180-188.
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© 2019 Institution of Chemical Engineers Pressure-assisted osmosis (PAO) has been suggested to integrate with fertiliser driven forward osmosis (FDFO) to improve the overall efficiency of simultaneous wastewater reuse and fertiliser osmotic dilution. This study aims to demonstrate the techno-economic feasibility of pressure-assisted fertiliser driven forward osmosis (PAFDO) hybrid system compared to the existing ultraviolet and reverse osmosis (UV–RO) process. The results showed that coupling FDFO with PAO (i.e. PAFDO) could help fulfill the water quality required for greenwall fertigation. An economic analysis on capital and operational costs for the PAFDO showed that the PAO mode application at a lower FDFO dilution stage could significantly reduce the costs. However, when considering the different applied pressures in PAO (i.e. 2, 4, and 6 bar), the increase in the total water cost was not significant. This indicates that the dilution stage for applying PAO is more sensitive to the total water cost of the PAFDO than the applied pressure. A coupling of higher average water flux (>10 L/m2h) and lower draw solution (DS) dilution factor (DF < 60) is recommended. Therefore, this could make the PAFDO system economically viable compared to the benchmark for the UV-RO disinfection system.
Kim, T, Alnahhal, MF, Nguyen, QD, Panchmatia, P, Hajimohammadi, A & Castel, A 2019, 'Initial sequence for alkali-silica reaction: Transport barrier and spatial distribution of reaction products', Cement and Concrete Composites, vol. 104, pp. 103378-103378.
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© 2019 Elsevier Ltd Alkali-silica reaction (ASR) is the result of complex chemical reactions. The exact sequence of ASR gel formation has yet to be fully understood. One promising hypothesis is that ASR gel starts to form only in localized regions where the availability of calcium is restricted. A transport barrier (C–S–H) around the aggregate has been hypothetically suggested. However, the existence of this physical barrier and the formation of ASR gel inside this barrier has been questioned because it has never been observed experimentally. This paper firstly presents a direct observation of the physical barrier, spatial distribution of reaction products, and crack formations in a reactive aggregate exposed to a model reactant system. Combined analyses using X-ray micro tomography and other chemical characterization techniques shows that ASR gel preferentially starts to form at localized areas covered by C–S–H, loosely packed reaction products with pores, and pre-existing defects.
Kim, Y, Li, S, Phuntsho, S, Xie, M, Shon, HK & Ghaffour, N 2019, 'Understanding the organic micropollutants transport mechanisms in the fertilizer-drawn forward osmosis process', Journal of Environmental Management, vol. 248, pp. 109240-109240.
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© 2019 Elsevier Ltd We systematically investigated the transport mechanisms of organic micropollutants (OMPs) in a fertilizer-drawn forward osmosis (FDFO) membrane process. Four representative OMPs, i.e., atenolol, atrazine, primidone, and caffeine, were chosen for their different molecular weights and structural characteristics. All the FDFO experiments were conducted with the membrane active layer on the feed solution (FS) side using three different fertilizer draw solutions (DS): potassium chloride (KCl), monoammonium phosphate (MAP), and diammonium phosphate (DAP) due to their different properties (i.e., osmotic pressure, diffusivity, viscosity and solution pH). Using KCl as the DS resulted in both the highest water flux and the highest reverse solute flux (RSF), while MAP and DAP resulted in similar water fluxes with varying RSF. The pH of the FS increased with DAP as the DS due to the reverse diffusion of NH4+ ions from the DS toward the FS, while for MAP and DAP DS, the pH of the FS was not impacted. The OMPs transport behavior (OMPs flux) was evaluated and compared with a simulated OMPs flux obtained via the pore-hindrance transport model to identify the effects of the OMPs structural properties. When MAP was used as DS, the OMPs flux was dominantly influenced by the physicochemical properties (i.e., hydrophobicity and surface charge). Those OMPs with positive charge and more hydrophobic, exhibited higher forward OMP fluxes. With DAP as the DS, the more hydrated FO membrane (caused by increased pH) as well as the enhanced RSF hindered OMPs transport through the FO membrane. With KCl as DS, the structural properties of the OMPs were dominant factors in the OMPs flux, however the higher RSF of the KCl draw solute may likely hamper the OMPs transport through the membrane especially those with higher MW (e.g., atenolol). The pore-hindrance model can be instrumental in understanding the effects of the hydrodynamic properties and the surface propertie...
Kordestani, MD, Naghibi, SA, Hashemi, H, Ahmadi, K, Kalantar, B & Pradhan, B 2019, 'Groundwater potential mapping using a novel data-mining ensemble model', Hydrogeology Journal, vol. 27, no. 1, pp. 211-224.
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© 2018, The Author(s). Freshwater scarcity is an ever-increasing problem throughout the arid and semi-arid countries, and it often results in poverty. Thus, it is necessary to enhance understanding of freshwater resources availability, particularly for groundwater, and to be able to implement functional water resources plans. This study introduces a novel statistical approach combined with a data-mining ensemble model, through implementing evidential belief function and boosted regression tree (EBF-BRT) algorithms for groundwater potential mapping of the Lordegan aquifer in central Iran. To do so, spring locations are determined and partitioned into two groups for training and validating the individual and ensemble methods. In the next step, 12 groundwater-conditioning factors (GCFs), including topographical and hydrogeological factors, are prepared for the modeling process. The mentioned factors are employed in the application of the EBF model. Then, the EBF values of the GCFs are implemented as input to the BRT algorithm. The results of the modeling process are plotted to produce spring (groundwater) potential maps. To verify the results, the receiver operating characteristics (ROC) test is applied to the model’s output. The findings of the test indicated that the areas under the ROC curves are 75 and 82% for the EBF and EBF-BRT models, respectively. Therefore, it can be inferred that the combination of the two techniques could increase the efficacy of these methods in groundwater potential mapping.
Kusuma, MH, Putra, N, Rosidi, A, Ismarwanti, S, Antariksawan, AR, Ardiyati, T, Juarsa, M & Mahlia, TMI 2019, 'Investigation on the Performance of a Wickless-Heat Pipe Using Graphene Nanofluid for Passive Cooling System', Atom Indonesia, vol. 45, no. 3, pp. 173-173.
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To enhance the thermal safety in case of station blackout, a wickless-heat pipe is proposed as an alternative passive cooling system technology to remove decay heat generation in the nuclear spent fuel storage pool. The objectives of this research are to investigate the heat transfer phenomena in vertical straight wickless-heat pipe using Graphene nanofluid working fluid and to study the effect of Graphene nanofluid on the vertical straight wickless-heat pipe thermal performance. The investigation was conducted in 6 meters height and 0.1016 m inside diameter of vertical straight wickless-heat pipe. In this research, the Graphene nanofluid with 1 % of weight concentration was used as working fluid. The effect of working fluid filling ratio, evaporator heat load, and coolant volumetric flow rate on the water jacket were studied. The results showed that the heat transfer phenomena, which were indicated by an overshoot, zigzag, and stable state, were observed. Based on thermal resistance obtained, it was shown that the vertical straight wickless-heat pipe charged with the Graphene nanofluid has a lower thermal resistance compared to one with demineralized water. The thermal resistance of vertical straight wickless-heat pipe using Graphene nanofluid and demineralized water were 0.015 °C/W and 0.016 °C/W, respectively. While the best thermal performance was achieved at a filing ratio of 80 %, higher heat load, and higher coolant volumetric flow rate. It can be concluded that Graphene nanofluid could enhance the thermal performance of vertical straight wickless-heat pipe.
Kusumo, F, Mahlia, TMI, Shamsuddin, AH, Ong, HC, Ahmad, AR, Ismail, Z, Ong, ZC & Silitonga, AS 2019, 'The Effect of Multi-Walled Carbon Nanotubes-Additive in Physicochemical Property of Rice Brand Methyl Ester: Optimization Analysis', Energies, vol. 12, no. 17, pp. 3291-3291.
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Biodiesel as an alternative to diesel fuel produced from vegetable oils or animal fats has attracted more and more attention because it is renewable and environmentally friendly. Compared to conventional diesel fuel, biodiesel has slightly lower performance in engine combustion due to the lower calorific value that leads to lower power generated. This study investigates the effect of multi-walled carbon nanotubes (MWCNTs) as an additive to the rice bran methyl ester (RBME). Artificial neural network (ANN) and response surface methodology (RSM) was used for predicting the calorific value. The interaction effects of parameters such as dosage of MWCNTs, size of MWCNTs and reaction time on the calorific value of RBME were studied. Comparison of RSM and ANN performance was evaluated based on the correlation coefficient (R2), the root mean square error (RMSE), the mean absolute percentage error (MAPE), and the average absolute deviation (AAD) showed that the ANN model had better performance (R2 = 0.9808, RMSE = 0.0164, MAPE = 0.0017, AAD = 0.173) compare to RSM (R2 = 0.9746, RMSE = 0.0170, MAPE = 0.0028, AAD = 0.279). The optimum predicted of RBME calorific value that is generated using the cuckoo search (CS) via lévy flight optimization algorithm is 41.78 (MJ/kg). The optimum value was obtained using 64 ppm of < 7 nm MWCNTs blending for 60 min. The predicted calorific value was validated experimentally as 41.05 MJ/kg. Furthermore, the experimental results have shown that the addition of MWCNTs was significantly increased the calorific value from 36.87 MJ/kg to 41.05 MJ/kg (11.6%). Also, the addition of MWCNTs decreased flashpoint (−18.3%) and acid value (−0.52%). As a conclusion, adding MWCNTs as an additive had improved the physicochemical properties characteristics of RBME. To our best knowledge, no research has yet been performed on the effect of multi-walled carbon nanotubes-additive in physicochemical property of rice brand methyl ester appli...
Lamqadem, AA, Saber, H & Pradhan, B 2019, 'Long-Term Monitoring of Transformation from Pastoral to Agricultural Land Use Using Time-Series Landsat Data in the Feija Basin (Southeast Morocco)', Earth Systems and Environment, vol. 3, no. 3, pp. 525-538.
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The expansion of agricultural land at the cost of pastoral land is the common cause of land degradation in the arid areas of developing countries, especially in Morocco. This study aims to assess and monitor the transformation of pastoral land to agricultural land in the arid environment of the Feija Basin (Southeast of Morocco) and to find the key drivers and the issues resulting from this transformation. Spectral mixture analysis was applied to multi-temporal (1975–2017) and multi-sensor (i.e. Multi-spectral Scanner, Thematic Mapper, and Operational Land Imager) Landsat satellite images, from which land use classifications were derived. The remote sensing data in combination with ground reference data (household level), groundwater and climate statistics were used to validate and explain the derived land use change maps. The results of the spatiotemporal changes in agricultural lands show two patterns of changes, a middle expansion from 1975 to 2007, and a rapid expansion from 2008 to 2017. In addition, the overall accuracy demonstrated a high accuracy of 94.4%. In 1975 and 1984, the agricultural lands in Feija covered 0.17 km and 1.32 km , respectively, compared with 20.10 km in 2017. Since the adoption of the Green Morocco Plan in 2008, the number of watermelon farms and wells has increased rapidly in the study area, which induced a piezometric level drawdown. The results show that spectral mixture analysis yields high accuracies for agricultural lands extraction in arid dry lands and accounts for mixed pixels issues. Results of this study can be used by local administrators to prepare an effective environmental management plan of these fragile drylands. The proposed method can be replicated in other regions to analyse land transformation in similar arid conditions. 2 2 2
Law, Y, Matysik, A, Chen, X, Swa Thi, S, Ngoc Nguyen, TQ, Qiu, G, Natarajan, G, Williams, RBH, Ni, B-J, Seviour, TW & Wuertz, S 2019, 'High Dissolved Oxygen Selection against Nitrospira Sublineage I in Full-Scale Activated Sludge', Environmental Science & Technology, vol. 53, no. 14, pp. 8157-8166.
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© 2019 American Chemical Society. A single Nitrospira sublineage I OTU was found to perform nitrite oxidation in full-scale domestic wastewater treatment plants (WWTPs) in the tropics. This taxon had an apparent oxygen affinity constant lower than that of the full-scale domestic activated sludge cohabitating ammonium oxidizing bacteria (AOB) (0.09 ± 0.02 g O2 m-3 versus 0.3 ± 0.03 g O2 m-3). Thus, nitrite oxidizing bacteria (NOB) may in fact thrive under conditions of low oxygen supply. Low dissolved oxygen (DO) conditions selected for and high aeration inhibited the NOB in a long-term lab-scale reactor. The relative abundance of Nitrospira sublineage I gradually decreased with increasing DO until it was washed out. Nitritation was sustained even after the DO was lowered subsequently. The morphologies of AOB and NOB microcolonies responded to DO levels in accordance with their oxygen affinities. NOB formed densely packed spherical clusters with a low surface area-to-volume ratio compared to the Nitrosomonas-like AOB clusters, which maintained a porous and nonspherical morphology. In conclusion, the effect of oxygen on AOB/NOB population dynamics depends on which OTU predominates given that oxygen affinities are species-specific, and this should be elucidated when devising operating strategies to achieve mainstream partial nitritation.
Lay, US, Pradhan, B, Yusoff, ZBM, Abdallah, AFB, Aryal, J & Park, H-J 2019, 'Data Mining and Statistical Approaches in Debris-Flow Susceptibility Modelling Using Airborne LiDAR Data', Sensors, vol. 19, no. 16, pp. 3451-3451.
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Cameron Highland is a popular tourist hub in the mountainous area of Peninsular Malaysia. Most communities in this area suffer frequent incidence of debris flow, especially during monsoon seasons. Despite the loss of lives and properties recorded annually from debris flow, most studies in the region concentrate on landslides and flood susceptibilities. In this study, debris-flow susceptibility prediction was carried out using two data mining techniques; Multivariate Adaptive Regression Splines (MARS) and Support Vector Regression (SVR) models. The existing inventory of debris-flow events (640 points) were selected for training 70% (448) and validation 30% (192). Twelve conditioning factors namely; elevation, plan-curvature, slope angle, total curvature, slope aspect, Stream Transport Index (STI), profile curvature, roughness index, Stream Catchment Area (SCA), Stream Power Index (SPI), Topographic Wetness Index (TWI) and Topographic Position Index (TPI) were selected from Light Detection and Ranging (LiDAR)-derived Digital Elevation Model (DEM) data. Multi-collinearity was checked using Information Factor, Cramer’s V, and Gini Index to identify the relative importance of conditioning factors. The susceptibility models were produced and categorized into five classes; not-susceptible, low, moderate, high and very-high classes. Models performances were evaluated using success and prediction rates where the area under the curve (AUC) showed a higher performance of MARS (93% and 83%) over SVR (76% and 72%). The result of this study will be important in contingency hazards and risks management plans to reduce the loss of lives and properties in the area.
Lee, J, Jung, H-S, Zlatanoya, S & Pradhan, B 2019, 'Editorial', International Journal of Urban Sciences, vol. 23, no. 3, pp. 301-302.
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Lee, S, Choi, J, Park, Y-G, Shon, H, Ahn, CH & Kim, S-H 2019, 'Hybrid desalination processes for beneficial use of reverse osmosis brine: Current status and future prospects', Desalination, vol. 454, pp. 104-111.
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© 2018 Elsevier B.V. As water shortage has increasingly become a serious global problem, desalination using seawater reverse osmosis (SWRO) is considered as a sustainable source of potable water sources. However, a major issue on the SWRO desalination plant is the generation of brine that has potential adverse impact due to its high salt concentration. Accordingly, it is necessary to develop technologies that allow environmentally friendly and economically viable management of SWRO brines. This paper gives an overview of recent research works and technologies to treat SWRO brines for its beneficial use. The treatment processes have been classified into two different groups according to their final purpose: 1) technologies for producing fresh water and 2) technologies for recovering energy. Topics in this paper includes membrane distillation (MD), forward osmosis (FO), pressure-retarded osmosis (PRO), reverse electrodialysis (RED) as emerging tools for beneficial use of SWRO brine. In addition, a new approach to simultaneously recover water and energy from SWRO brine is introduced as a case study to provide insight into improving the sustainability of seawater desalination.
Leong, KY, Chew, SP, Gurunathan, BA, Ku Ahmad, KZ & Ong, HC 2019, 'An experimental approach to investigate thermal performance of paraffin wax and 1-hexadecanol based heat sinks for cooling of electronic system', International Communications in Heat and Mass Transfer, vol. 109, pp. 104365-104365.
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© 2019 Elsevier Ltd The efficiency and life span of an electronic device or system depends on its operating temperature. Longer operation period in elevated temperatures leads to system failure. In addition, miniaturization of electronic device and generation of high energy density are the current trend in this field. Therefore, an efficient cooling system is vital for ensuring this system operates in optimum temperature. Integration of heat sinks together with phase change material (PCM) can be adapted to dissipate heat generation by electronic system. This study intends to investigate thermal performance of various configuration of cross-fin heat sinks with and without PCM. Two types of PCMs considered are paraffin wax and 1-hexadecanol. The study implies that addition of fins and PCM capable of augmented thermal performance of the heat sinks. Higher number of cross-fin and amount of PCM led to lower heat sinks base temperature. The base temperature of heat sinks with cross-fin (16 square cavities) fully added with paraffin wax is 46.9 °C compared to 51.6 °C observed for similar heat sinks without paraffin wax. Heat sinks filled with paraffin wax performed better than heat sinks filled with 1-hexadecanol. This translates to lower base heat sinks temperature especially at the mid-region of the test period.
Li, CY, Chen, SJ, Li, WG, Li, XY, Ruan, D & Duan, WH 2019, 'Dynamic increased reinforcing effect of graphene oxide on cementitious nanocomposite', Construction and Building Materials, vol. 206, pp. 694-702.
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© 2019 The reinforcing effect of graphene oxide on cementitious materials under high strain rate remains largely unknown. Existing studies on microfiber reinforced cementitious composites showed that the dynamic increase factor (DIF) decreases due to these fibres. This study reports that the reinforcing effect of graphene oxide nanosheets can, in contrast, increase with strain rate. Tensile splitting and compression tests were conducted under both static and dynamic loadings. High strain rate, up to 1700 s −1 , is achieved using a split Hopkinson pressure bar apparatus. It is found that the DIF of graphene oxide nanocomposite only increase when the DIF is higher than a threshold which is about 780 and 30 s −1 for compression and tensile test respectively. The increased of DIF was correlated with the speed of crack development and pull-out of the graphene oxide nanosheets. Also, the pull-out or fracture of graphene oxide on fragmented sand was also found a possible contributing factor to the increased DIF. The findings of this study indicate the future potential of atomic-thin nanosheets for materials under extreme impact and blast loading.
Li, J, Zhu, X, Law, S-S & Samali, B 2019, 'Drive-By Blind Modal Identification with Singular Spectrum Analysis', Journal of Aerospace Engineering, vol. 32, no. 4, pp. 04019050-04019050.
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© 2019 American Society of Civil Engineers. Drive-by bridge parameter identification has been an active research area in recent years. An instrumented vehicle passing over a bridge deck captures dynamic information of the bridge structure without bridge closure and on-site instrumentation. The vehicle dynamic response includes components associated with the bridge surface roughness and the vehicle and bridge vibration. It is a challenge to separate these components and extract the bridge modal parameters from the vehicle response. A novel drive-by blind modal identification with singular spectrum analysis is proposed to extract the bridge modal frequencies from the vehicle dynamic response. The single-channel measured vehicular response is decomposed into a multichannel data set using singular spectrum analysis, and the bridge frequencies are then extracted via the blind modal identification. Numerical results showed that the proposed method is effective and robust to extract the bridge frequencies from the vehicle response measurement even with Class B road surface roughness. The effects of the moving speed and the vehicle parameters on the identification were studied. A vehicle-bridge interaction model in the laboratory was studied to further verify the proposed method using one- and two-axle vehicles.
Li, J, Zhu, X, Law, S-S & Samali, B 2019, 'Indirect bridge modal parameters identification with one stationary and one moving sensors and stochastic subspace identification', Journal of Sound and Vibration, vol. 446, pp. 1-21.
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© 2019 Elsevier Ltd A new indirect strategy is proposed to estimate the bridge modal parameters from the dynamic responses of two vehicles using stochastic subspace identification technique. The effect of ambient excitation, such as ongoing traffic, is simulated as white-noise excitation at the bridge supports. The state-space model of the vehicle-bridge interaction system is derived for a single-degree-of-freedom quarter-car model and the bridge deck modeled as a simply-supported Euler-Bernoulli beam. Bridge modal frequencies can be estimated accurately from the vehicle responses. Two instrumented vehicles are required to estimate the bridge mode shapes, with one serving as a fixed reference sensor and the other as a moving sensor. The measured accelerations from the vehicles are divided into segments and each pair of signal segments forms a state-space identification problem. Local mode shape value from each signal segment can be estimated using the reference-based SSI method. A rescaling on the local mode shape values is applied to construct the global mode shapes. Effects of the bridge surface roughness, measurement noise and vehicle properties on the mode shape identification are also numerically studied. A vehicle-bridge interaction model in the laboratory serves for the experimental validation of the proposed strategy. Both numerical and experimental results show that the proposed method can estimate the bridge modal parameters with acceptable accuracy.
Li, K, Wu, D & Gao, W 2019, 'Spectral stochastic isogeometric analysis for linear stability analysis of plate', Computer Methods in Applied Mechanics and Engineering, vol. 352, pp. 1-31.
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Li, K, Wu, D, Gao, W & Song, C 2019, 'Spectral stochastic isogeometric analysis of free vibration', Computer Methods in Applied Mechanics and Engineering, vol. 350, pp. 1-27.
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A novel spectral stochastic isogeometric analysis (SSIGA) is proposed for the free vibration analysis of engineering structures involving uncertainties. The proposed SSIGA framework treats the stochastic free vibration problem as a stochastic generalized eigenvalue problem. The stochastic Young's modulus and material density of the structure are modelled as random fields with Gaussian and non-Gaussian distributions. The basis functions, the non-uniform rational B-spline (NURBS) and T-spline, within Computer Aided Design (CAD) system are adopted within the SSIGA, which can eliminate geometric errors between design model and uncertainty analysis model. The arbitrary polynomial chaos (aPC) expansion is implemented to investigate the stochastic responses (i.e. eigenvalues and eigenvectors) of the structure. A Galerkin-based method is freshly proposed to solve the stochastic generalized eigenvalue problems. The statistical moments, probability density function (PDF) and cumulative distribution function (CDF) of the eigenvalues can be effectively obtained. Two numerical examples with irregular geometries are investigated to illustrate the applicability, accuracy and efficiency of the proposed SSIGA for free vibration analysis of engineering structures.
Li, L, Geng, S, Wu, C, Song, K, Sun, F, Visvanathan, C, Xie, F & Wang, Q 2019, 'Microplastics contamination in different trophic state lakes along the middle and lower reaches of Yangtze River Basin', Environmental Pollution, vol. 254, no. Pt A, pp. 112951-112951.
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© 2019 Elsevier Ltd Microplastics can enter freshwater lakes through many sources. They can act as carriers to adsorb bacteria, virus, or pollutants (e.g., heavy metal and toxic organic compounds) that threaten human health through food chain. Microplastics can exist in surface water and sediments in freshwater lakes after they enter the lakes through discharge points. Wastewater discharge is the main cause of lake eutrophication and is the main emission source of microplastics. The correlation between lake trophic state and microplastic abundance has been rarely reported. This study investigated the microplastic contamination in surface water and sediments of 18 lakes along the middle and lower reaches of the Yangtze River Basin in the period of August–September 2018. The correlation between lake trophic state and microplastic abundance in surface water and sediments was investigated and discussed. The microplastic abundance in surface water was approximately two orders of magnitude lower than that in sediments in all 18 lakes. Hong Lake had the highest microplastic abundance in surface water sample, and Nantaizi Lake had the highest microplastic abundance in sediment sample. The dominant microplastic shape was fiber of 93.81% in surface water sample and 94.77% in sediment sample. Blue-colored microplastics were dominant in nearly all lakes in surface water sample (around 40%–60%) and sediment sample (around 60%–80%), followed by purple- and green-colored ones. The microplastics size <1 mm was dominant in surface water sample (around 40%–60%) and sediment sample (around 50%–80%). The dominant material was polypropylene in surface water sample (around 60%–80%) and sediment sample (around 40%–60%).
Li, L-Q, Ju, N-P, Zhang, S, Deng, X-X & Sheng, D 2019, 'Correction to: Seismic wave propagation characteristic and its effects on the failure of steep jointed anti-dip rock slope', Landslides, vol. 16, no. 1, pp. 125-126.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The published version of this article, unfortunately, contained error. A compass went unconverted in the upper-right corner of Fig. 1. Given in this article is the correct image. The original article has been corrected.
Li, L-Q, Ju, N-P, Zhang, S, Deng, X-X & Sheng, D 2019, 'Seismic wave propagation characteristic and its effects on the failure of steep jointed anti-dip rock slope', Landslides, vol. 16, no. 1, pp. 105-123.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. Discontinuities, such as joints and beddings, usually play a significant role in the seismic response and corresponding failure process of slopes, especially for anti-dip rock slide according to field observations. Shaking table tests associated with numerical analyses are carried out in this paper to explore the effect of seismic wave on response of jointed anti-dip rock slopes. Shaking table tests involve anti-dip rock slope models with different rock types and different excitation intensities. Ten accelerometers are installed inside each slope model to monitor the dynamic response and spectrum shifting characteristics. It is found that the area of failure zone in the soft rock anti-dip slope is approximate 1.5 times the size of that in the hard rock anti-dip slope. Meanwhile, the width and ridge number of the fast Fourier-transformation spectrum along the slope surface can reveal the internal damage features within the anti-dip rock slopes, and the multiple failure planes can also be recognized according to the variation of distance between the innermost and outermost ridges in the fast Fourier-transformation spectrum. Moreover, the distinct element method incorporating a damage model is used to interpret the test results and to identify the main influencing factors for seismic instability. It is found that the failure pattern of a jointed anti-dip rock slope is more sensitive to bedding inclination than to joint inclination.
Li, Q, Wang, Q, Wu, D, Chen, X, Yu, Y & Gao, W 2019, 'Geometrically nonlinear dynamic analysis of organic solar cell resting on Winkler-Pasternak elastic foundation under thermal environment', Composites Part B: Engineering, vol. 163, pp. 121-129.
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© 2018 Elsevier Ltd The nonlinear dynamic responses of a nanocomposite organic solar cell (NCOSC) are developed through the classical plate theory. The investigated NCOSC consists of five layers which are including Al, P3HT: PCBM, PEDOT: PSS, IOT and glass. A uniformly distributed external excitation is exerted on the simply supported NCOSC. The impacts of the Winkler-Pasternak elastic foundation, thermal environment and damping on the nonlinear dynamic responses of the NCOSC are investigated. The equations of motion and geometric compatibility of the NCOSC with the consideration of the von Kármán nonlinearity are derived. The governing equation of the dynamic system is formulated by employing the Galerkin and the fourth-order Runge-Kutta methods. Several numerical experiments are thoroughly presented to report the effects of damping ratio, temperature variations, and elastic foundation parameters on the frequency–amplitude curves and nonlinear dynamic response of the NCOSC. The numerical studies indicate that the existence of the Winkler-Pasternak elastic foundation effectively reduces the dynamic response of the NCOSC. In addition, the damping and thermal variation depress the vibration of the NCOSC but with relatively less efficiency compared with the Winkler- Pasternak elastic foundation.
Li, Q, Wu, D, Gao, W, Tin-Loi, F, Liu, Z & Cheng, J 2019, 'Static bending and free vibration of organic solar cell resting on Winkler-Pasternak elastic foundation through the modified strain gradient theory', European Journal of Mechanics - A/Solids, vol. 78, pp. 103852-103852.
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© 2019 Elsevier Masson SAS Organic solar cell (OSC), which is deemed to be the most promising third generation solar energy application, is developing vigorously. Based on the modified strain gradient theory (MSGT) and the refined shear deformation plate theory, static bending and free vibration of the size-dependent OSC are thoroughly investigated in this paper. A Winkler-Pasternak elastic foundation is considered for the OSC. A multiscale suitable plate analysis framework (i.e., both macro- and micro plates can be handled) is developed herein. Three length scale parameters are incorporated in the presented analysis to capture the size-dependency of the OSC. By setting two or three of them into zero, the presented model could degenerate into the modified couple stress theory (MCST) and the classical plate theory (CPT). The derivation of the governing equations and the corresponding boundary conditions are conducted by Hamilton principle. The Navier-type solution is employed for solving the governing equations of the simply supported OSC. The accuracy of the presented method is validated. Extensive numerical experiments have been conducted to investigate the differences between the adopted MSGT, the MCST and the CPT. Moreover, the impacts of the geometrical configuration as well as the elastic foundation parameters on the static bending and free vibration characteristics are illustrated in the numerical studies. This paper also explores the thickness of the active layer effect on the free vibration behaviour in combination with the power conversion efficiency (PCE) of the OSC.
Li, W, Li, J, Liu, Y, Qu, J, Liu, B, Zhu, M, Li, Y, Huang, Z & Zheng, R 2019, 'Artificial 2D Flux Pinning Centers in MgB2 Induced by Graphitic-Carbon Nitride Coated on Boron for Superconductor Applications', ACS Applied Nano Materials, vol. 2, no. 9, pp. 5399-5408.
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© 2019 American Chemical Society. Systemic investigation was carried out on the microstructure, superconducting properties, and flux pinning mechanism of MgB2 in situ fabricated with magnesium and g-C3N4 coated boron as precursors. The encapsulation of the boron powders with g-C3N4 was achieved by polycondensation of urea on boron powders. The g-C3N4 decomposes during the MgB2 fabrication to induce two-dimensional few-carbon layer, dispersed nanoparticles, and carbon-rich phases in the matrix to enhance the flux pinning force and Hirr of MgB2, which accounts for the in-field critical current density (Jc(H)) increase compared to the pure MgB2. The carbon layers acting as artificial two-dimensional flux pinning centers, have demonstrated high flux pinning efficiency to increase the Jc(H) of MgB2 superconductors.
Li, X, Liu, Y, Xu, Q, Liu, X, Huang, X, Yang, J, Wang, D, Wang, Q, Liu, Y & Yang, Q 2019, 'Enhanced methane production from waste activated sludge by combining calcium peroxide with ultrasonic: Performance, mechanism, and implication', Bioresource Technology, vol. 279, pp. 108-116.
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© 2019 Elsevier Ltd This study reported a novel and high-efficient pretreatment method for anaerobic digestion, i.e., combining calcium peroxide (CaO2) with ultrasonic (US), by which not only the methane production was remarkably improved but also the removal of refractory organic contaminants was enhanced. Experimental results showed the optimum condition for methane production was achieved at 0.1 g CaO2/g VSS combined with US (1 W/ml, 10 min). Under this condition, the maximal methane yield of 211.90 ± 2.6 L CH4/kg VSS was obtained after 36 d of anaerobic digestion, which was respectively 1.36-fold, 1.19-fold and 1.26-fold of that from the control, solo US (1 W/ml, 10 min) and solo CaO2 (0.1 g/g VSS). Mechanism investigations revealed that CaO2 + US not only improved the disintegration of waste activated sludge (WAS) but also increased the proportion of biodegradable organic matters. Moreover, the total frequency of recalcitrant contaminants contained in WAS decreased significantly when CaO2 + US was applied.
Li, X, Mei, Q, Chen, L, Zhang, H, Dong, B, Dai, X, He, C & Zhou, J 2019, 'Enhancement in adsorption potential of microplastics in sewage sludge for metal pollutants after the wastewater treatment process', Water Research, vol. 157, pp. 228-237.
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© 2019 Elsevier Ltd Microplastics (MPs) as new pollutants of environmental concern have been widely detected in sewage sludge, and may act as significant vectors for metal pollutants due to their adsorption property. Our findings show that Cd, Pb, and Co, but not Ni, contents in sewage sludge are lower than that of corresponding metal irons adsorbed on sludge-based MPs, indicating that the MPs accumulate such metal pollutants as Cd in the sludge samples. In contrast to virgin MPs, sludge-based MPs are one order of magnitude higher adsorption capacity for Cd, which reaches up to 2.523 mg g−1, implying that there is a considerable enhancement in adsorption potential of the MPs for metals after the wastewater treatment process. SEM analysis shows that sludge-based MPs have rougher and more porous surface than virgin MPs, and FTIR spectra reveal that functional groups such as C–O and O–H are found on sludge-based MPs. Further, two-dimensional FTIR correlation spectroscopy indicates that C–O and N–H functional groups play a vital role in the process that sludge-based MPs adsorb Cd, which are not found in virgin MPs. The results imply that increased adsorption potentials of the sludge-based MPs to Cd are attributed to changes in the MP physicochemical properties during wastewater treatment process. In addition, such factors as pH value, and sludge inorganic and organic components also have an effect on the MP adsorption to Cd. Principal component analysis shows that the MPs could be divided into three categories, i.e. polyamide, rubbery MPs (polyethylene and polypropylene) and glassy MPs (polyvinyl chloride and polystyrene). Their adsorption potentials to Cd follow the decreasing order: polyamide > rubbery MPs > glassy MPs. In summary, these findings indicate that MPs may exert an important influence on fate and transport of metal pollutants during sewage sludge treatment process, which deserves to be further concerned.
Li, Y, Huang, C, Ngo, HH, Pang, J, Zha, X, Liu, T & Guo, W 2019, 'In situ reconstruction of long-term extreme flooding magnitudes and frequencies based on geological archives', Science of The Total Environment, vol. 670, pp. 8-17.
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© 2019 Extreme flooding magnitudes and frequencies are essentially related to assessment of risk and reliability in hydrological design. Extreme flooding and its discharge are highly sensitive to regional climate change. Presently, its discharge can be reconstructed by a geological archive or record along the river valley. Two units of typical extreme flooding deposits (EFDs) carrying long-term information preserved in the Holocene loess–palaeosol sequence were found at Xipocun (XPC), which is located in Chengcheng County, China. It is situated in the downstream section of the Beiluohe (hereafter BLH) River. Based on multiple sedimentary proxy indices (grain-size distribution (GSD), magnetic susceptibility (MS), and loss-on-ignition (LOI), etc.), EFDs were interpreted as well-sorted clayey silt in suspension. They were then deposited as a result of riverbank flooding in a stagnant environment during high water level. Through the Optically Stimulated Luminescence (OSL) dating technique and stratigraphic correlations, chronologies of two identified extreme flooding periods were 7600–7400 a B.P. and 3200–3000 a B.P. Two phases of extreme flooding occurrence under climate abnormality scenarios were characterized as having high frequencies of hydrological extremes in river systems. According to simulation and verification using the Slope–Area Method and Hydrologic Engineering Center's River Analysis System (HEC-RAS) model, the extreme flooding discharges at the XPC site were reconstructed between 9625 m 3 /s and 16,635 m 3 /s. A new long-term flooding frequency and peak discharge curve, involved gauged flooding, historical flooding at Zhuangtou station and in situ reconstructed extreme flooding events, was established for the downstream BLH River. The results improve the accuracy of low-frequency flooding risk assessment and provide evidence for predicting the response of fluvial systems to climate instability. Thus, this improves the analysis of the BLH River watershed.
Liang, X, Wu, C, Yang, Y & Li, Z 2019, 'Experimental study on ultra-high performance concrete with high fire resistance under simultaneous effect of elevated temperature and impact loading', Cement and Concrete Composites, vol. 98, pp. 29-38.
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© 2019 Fire is a big risk to buildings and structures, posing a great threat to human lives. In this study, a newly developed ultra-high performance concrete (UHPC) was investigated experimentally. Quasi-static compression tests were conducted after the UHPC was first exposed to a high temperature, i.e. 200, 400, 600, 800 or 1000 °C, and then cooled down to room temperature, while dynamic tests were carried out under combined effect of a high temperature, i.e. 200, 400, 600, or 800 °C, and impact loading. The dynamic tests were done both at high temperatures and after cooling down and comparisons were made between these two scenarios. Based on the tests on this UHPC, mechanical and physical characteristics under the combined effect were studied. Besides, explosive spalling was analysed. It was interesting to find polypropylene (PP) fibre could play a negative role in preventing explosive spalling between 320 and 380 °C.
Liang, X, Wu, C, Yang, Y, Wu, C & Li, Z 2019, 'Coupled effect of temperature and impact loading on tensile strength of ultra-high performance fibre reinforced concrete', Composite Structures, vol. 229, pp. 111432-111432.
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© 2019 Elsevier Ltd This study focused on coupled effect of temperature and impact loading on tensile strength of an ultra-high performance fibre reinforced concrete (UHPFRC), which retains 69% of its original compressive strength after exposure to 1000 °C. The relationship between tensile strength and compressive strength was investigated under the coupled action since temperature may have different effects on them. Static tests and dynamic tests using a self-designed Split Hopkinson Pressure Bar (SHPB) system were conducted at temperatures 20, 200, 400, 600 and 800 °C. Comparison was made between tensile strength and compressive strength of UHPFRC obtained in hot state and cooled-down state. It was found splitting tensile strength fell sharply beyond 400 °C but still retained 41% of its original strength at 800 °C, well above other concretes. Temperature and combined action of elevated temperature and impact loading have different effects on splitting tensile strength and compressive strength.
Lim, S, Tran, VH, Akther, N, Phuntsho, S & Shon, HK 2019, 'Defect-free outer-selective hollow fiber thin-film composite membranes for forward osmosis applications', Journal of Membrane Science, vol. 586, pp. 281-291.
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© 2019 Elsevier B.V. This study presents the successful fabrication of a novel defect-free outer-selective hollow fiber (OSHF) thin-film composite (TFC) membrane for forward osmosis (FO) applications. Thin and porous FO membrane substrates made of polyether sulfone (PES) with a dense and smooth outer surface were initially fabricated at different air-gap distances. A modified vacuum-assisted interfacial polymerization (VAIP) technique was then successfully utilised for coating polyamide (PA) layer on the hollow fiber (HF) membrane substrate to prepare OSHF TFC membranes. Experimental results showed that the molecular weight cut-off (MWCO) of the surface of the membrane substrate should be less than 88 kDa with smooth surface roughness to obtain a defect-free PA layer via VAIP. The FO test results showed that the newly developed OSHF TFC membranes achieved water flux of 30.2 L m−2 h−1 and a specific reverse solute flux of 0.13 g L−1 using 1 M NaCl and DI water as draw and feed solution, respectively. This is a significant improvement on commercial FO membranes. Moreover, this OSHF TFC FO membrane demonstrated higher fouling resistance and better cleaning efficiency against alginate-silica fouling. This membrane also has a strong potential for scale-up for use in larger applications. It also has strong promise for various FO applications such as osmotic membrane bioreactor (OMBR) and fertilizer-drawn OMBR processes.
Lin, B-J, Chen, W-H, Hsieh, T-H, Ong, HC, Show, PL & Naqvi, SR 2019, 'Oxidative reaction interaction and synergistic index of emulsified pyrolysis bio-oil/diesel fuels', Renewable Energy, vol. 136, pp. 223-234.
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Liu, F, Nattestad, A, Naficy, S, Han, R, Casillas, G, Angeloski, A, Sun, X & Huang, Z 2019, 'Fluorescent Carbon‐ and Oxygen‐Doped Hexagonal Boron Nitride Powders as Printing Ink for Anticounterfeit Applications', Advanced Optical Materials, vol. 7, no. 24, pp. 1901380-1901380.
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AbstractIncreasing demands for optical anticounterfeiting technology require the development of versatile luminescent materials with tunable photoluminescence properties. Herein, a number of fluorescent carbon‐ and oxygen‐doped hexagonal boron nitride (denoted as BCNO) phosphors are found to offer a such high‐tech anticounterfeiting solution. These multicolor BCNO powders, developed in a two‐step process with controlled annealing and oxidation, feature rod‐like particle shape, with varied luminescence properties. Studies of the optical properties of BCNO, along with other characterization, provide insight into this underexplored material. Anticounterfeiting applications are demonstrated with printed patterns which are indistinguishable to the naked eye under visible light but become highly discernible under UV irradiation. The fabricated patterns are demonstrated to be both chemically stable in corrosive environments and physically robust in mechanical bending testing. These properties render BCNO as promising and versatile anticounterfeiting material a wide variety of environments.
Liu, H, Zhou, X, Ding, W, Zhang, Z, Nghiem, LD, Sun, J & Wang, Q 2019, 'Do Microplastics Affect Biological Wastewater Treatment Performance? Implications from Bacterial Activity Experiments', ACS Sustainable Chemistry & Engineering, vol. 7, no. 24, pp. 20097-20101.
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© 2019 American Chemical Society. Microplastics have been ubiquitously detected in the wastewater treatment plants, while their effects on the activities of wastewater treatment bacteria have never been evaluated. This study investigated the effects of polyester (PES), polyethylene (PE), and polyvinyl chloride (PVC) microplastics (100-1200 μm; 50-10000 particles/L) on the activities of ammonium-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), denitrifiers, and polyphosphate-accumulating organisms (PAOs). The activities of AOB and NOB without microplastics addition are 6.3 ± 0.3 and 4.0 ± 0.4 mg N/g MLVSS/h (MLVSS: mixed liquor volatile suspended solids), which are similar (p > 0.05) to their activities (5.2 ± 0.7 to 6.8 ± 0.8 and 3.7 ± 0.9 to 5.1 ± 0.8 mg N/g MLVSS/h) with microplastics addition. Similarly, the activities of denitrifiers and PAOs without microplastics addition (14.1 ± 1.1 mg N/g MLVSS/h and 29.2 ± 0.9 mg P/g MLVSS/h) are comparable (p > 0.05) to those with microplastics addition (12.8 ± 1.2 to 15.1 ± 0.5 mg N/g MLVSS/h and 28.0 ± 1.1 to 29.7 ± 2.4 mg P/g MLVSS/h). The results demonstrated that microplastics do not significantly affect the activities of AOB, NOB, denitrifiers, and PAOs, and therefore the effect of microplastics on the wastewater treatment performance should not be overemphasized.
Liu, J, Wu, C, Li, C, Dong, W, Su, Y, Li, J, Cui, N, Zeng, F, Dai, L, Meng, Q & Pang, J 2019, 'Blast testing of high performance geopolymer composite walls reinforced with steel wire mesh and aluminium foam', Construction and Building Materials, vol. 197, pp. 533-547.
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© 2018 Elsevier Ltd Two blast tests were conducted to study the blast resistance of high performance geopolymer composite walls reinforced with steel wire mesh (SWM) and aluminium foam (AF). Conventional reinforced concrete (CRC) walls were also tested as control specimens. In total seven walls were tested under different blast loading conditions. The first blast test was conducted on one 2260 mm × 2260 mm × 150 mm SWM reinforced, one 2260 mm × 1000 mm × 150 mm SWM reinforced and one 2260 mm × 1000 mm × 150 mm combined SWM and AF reinforced high performance geopolymer composite walls under 50 kg TNT explosives at a standoff distance of 2.3 m. The second blast test was conducted on one 2260 mm × 2260 mm × 150 mm SWM reinforced and one 2260 mm × 2260 mm × 150 mm combined SWM and AF reinforced high performance geopolymer composite walls under 100 kg TNT explosives on the ground at the same standoff distance. Blast tests were also performed on two 2260 mm × 2260 mm × 150 mm CRC walls under such two designed explosions to compare their behaviours with reinforced high performance geopolymer composite walls. LVDT (linear variable differential transformer) devices were used to record the deflection histories and pressure sensors were used to measure the airblast pressure histories. The testing results indicated that the combined SWM and AF reinforced high performance geopolymer composite walls had a better blast resistance than the CRC walls, and the SWM reinforced high performance geopolymer composite wall was superior to both.
Liu, J, Wu, C, Li, J, Fang, J, Su, Y & Shao, R 2019, 'Ceramic balls protected ultra-high performance concrete structure against projectile impact–A numerical study', International Journal of Impact Engineering, vol. 125, pp. 143-162.
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© 2018 Elsevier Ltd Ceramic materials have excellent mechanical properties such as light weight, great hardness and high compressive strength. In this paper, a numerical study is conducted to investigate the response of ceramic balls protected ultra-high performance concrete (UHPC) targets against the high-velocity rigid projectile impact using the coupled smoothed particle hydrodynamics-finite element (SPH-FE) method in LS-DYNA. Based on the validated numerical models, parametric studies are performed to explore the effect of diameter, spatial arrangement and material type of ceramic balls as well as the impact position on the dynamic performance of UHPC targets, and then perforation and ballistic limits of ceramic balls protected UHPC targets are obtained. Compared with other UHPC slabs at the striking velocities from 500 m/s to 850 m/s, UHPC slabs protected with 6-layer hex-pack arranged ceramic balls with the diameter of 20 mm is most effective in terms of reducing the depth of penetration (DOP). In addition, the utilization of ceramic balls is economical in protective structures since the damaged ceramic balls can be replaced and undamaged ceramic balls are reusable.
Liu, M, Nothling, MD, Webley, PA, Fu, Q & Qiao, GG 2019, 'Postcombustion Carbon Capture Using Thin-Film Composite Membranes', Accounts of Chemical Research, vol. 52, no. 7, pp. 1905-1914.
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Climate change due to anthropogenic carbon dioxide emissions (e.g., combustion of fossil fuels) represents one of the most profound environmental disasters of this century. Equipping power plants with carbon capture and storage (CCS) technology has the potential to reduce current worldwide CO2 emissions. However, existing CCS schemes (i.e., amine scrubbing) are highly energy-intensive. The urgent abatement of CO2 emissions relies on the development of new, efficient technologies to capture CO2 from existing power plants. Membrane-based CO2 separation is an attractive technology that meets many of the requirements for energy-efficient industrial carbon capture. Within this domain, thin-film composite (TFC) membranes are particularly attractive, providing high gas permeance in comparison with conventional thicker (∼50 μm) dense membranes. TFC membranes are usually composed of three layers: (1) a bottom porous support layer; (2) a highly permeable intermediate gutter layer; and (3) a thin (<1 μm) species-selective top layer. A key challenge in the development of TFC membranes has been to simultaneously maximize the transmembrane gas permeance of the assembled membrane (by minimizing the gas resistance of each layer) while maintaining high gas-specific selectivity. In this Account, we provide an overview of our recent development of high-performance TFC membrane materials as well as insights into the unique fabrication strategies employed for the selective layer and gutter layer. Optimization of each layer of the membrane assembly individually results in significant improvements in overall membrane performance. First, incorporating nanosized fillers into the selective layer (poly(ethylene glycol)-based polymers) and reducing its thickness (to ca. 50 nm) through continuous assembly of polymers technology yields major improvements in CO2 permeance without loss of selectivity. Second, we focus on optimization of the middle gutter layer of TFC membranes. The de...
Liu, R, Zhao, Y, Li, W, Wang, Q, Shen, C, Awe, OW & Hao, X 2019, 'Dynamics of the activated sludge in a newly-defined green bio-sorption reactor (GBR)', Chemical Engineering Journal, vol. 374, pp. 1046-1054.
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© 2019 Elsevier B.V. When upgrading an aging wastewater treatment plant (WWTP), the sludge management line is always out of consideration in terms of cost and easy-operation. This study presented the dynamics of the sludge when upgrading a conventional sequencing batch reactor (SBR) to green bio-sorption reactor (GBR) by embedding alum sludge-based constructed wetland (AlCW). The aluminum (Al(III)) content in the effluent and the resultant impact on organisms were also evaluated. The results showed that the Al(III) residues was at an acceptable level (<0.2 mg/L). The AlCW and its leachate Al(III) did not pose any detrimental impact on the activity of heterotrophic organisms and the nitrifiers whereas the activity of the polyphosphate accumulating organisms was completely suppressed and eliminated out of the reactor. In addition, the Al(III) hydroxides and natural organic matter promoted the flocculation of activated sludge flocs by complexation with the extracellular polymeric substances. As a result, the larger and compact activated sludge led to an increase of the settling velocity and the dewatering efficiency while deteriorating the sludge compressibility (sludge volume index of 150 mL/g). Interestingly, this laboratory-scale GBR was verified to be a promising alternative to upgrade the ageing WWTPs simultaneously with an improvement of the dewatering properties of the activated sludge.
Liu, T, Sun, G, Fang, J, Zhang, J & Li, Q 2019, 'Topographical design of stiffener layout for plates against blast loading using a modified ant colony optimization algorithm', Structural and Multidisciplinary Optimization, vol. 59, no. 2, pp. 335-350.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. The stiffened plates are of demonstrable advantages and potential in offering high resistance to such extreme loading scenarios as blast. Since the distribution of the stiffeners has considerable effect on their performance, its design signifies an important topic of research. However, existing research has mainly focused on empirical design, and the configurations were largely experience based, which limits structural explosion-proof capacity. In order to improve the performance of stiffened plates against blast loading, we introduced here two new structural configurations of stiffened plates. In this study, the modified ant colony optimization (MACO) algorithm which introduces the mass constraint factor to the pheromone update function and integrates the idea of crossover and mutation was used to design the subjected to given working conditions. Specifically, material distribution of stiffeners is taken to be the design variables, and minimization of the maximum deflection of the center point of the plate to be the design objective under predetermined mass constraints. Compared with the baseline structure, the optimal designs largely improved the explosion-proof performance through distributing stiffener topology on the plates. The results showed that the optimum designs all present the reinforcement stiffeners to link with the fixed boundaries against the deformation. Moreover, the optimum designs placed more reinforcement materials in the central regions instead of four angles, and with the increase of the mass fraction, the reinforcement placement gradually extends from the center to the edges. The proposed method and new topological configurations are expected to provide some insights into design for novel protective structures.
Liu, X, Duan, X, Wei, W, Wang, S & Ni, B-J 2019, 'Photocatalytic conversion of lignocellulosic biomass to valuable products', Green Chemistry, vol. 21, no. 16, pp. 4266-4289.
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This review summarizes the state-of-the-art accomplishments in photocatalytic conversion of lignocellulosic biomass and its derivatives.
Liu, X, Xu, Q, Wang, D, Wu, Y, Fu, Q, Li, Y, Yang, Q, Liu, Y, Ni, B-J, Wang, Q, Yang, G, Li, H & Li, X 2019, 'Microwave pretreatment of polyacrylamide flocculated waste activated sludge: Effect on anaerobic digestion and polyacrylamide degradation', Bioresource Technology, vol. 290, pp. 121776-121776.
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© 2019 Elsevier Ltd Deterioration of anaerobic digestion can occur with the presence of polyacrylamide (PAM) in waste activated sludge, but the information on alleviating this deterioration is still limited. In this study, the simultaneous alleviation of negative effect of PAM and improvement of methane production during anaerobic digestion was accomplished by microwave pretreatment. Experimental results showed that with the microwave pretreatment times increased from 0 to 12 min, the biochemical methane potential of PAM-flocculated sludge (12 g PAM/kg total solids) asymptotically increased from 123.1 to 242.5 mL/g volatile solids, hydrolysis rate increased from 0.06 to 0.13 d−1. Mechanism analysis indicated that the microwave pretreatment accelerated the release and hydrolysis of organic substrates from PAM-flocculated sludge, facilitated the breaking of large firm “PAM-sludge” floccules, and benefited the degradation of PAM, which alleviated the PAM inhibitory impacts on digestion and meanwhile provided better contact between the released organic substrates and anaerobic bacteria for methane production.
Liu, X, Xu, Q, Wang, D, Wu, Y, Yang, Q, Liu, Y, Wang, Q, Li, X, Li, H, Zeng, G & Yang, G 2019, 'Unveiling the mechanisms of how cationic polyacrylamide affects short-chain fatty acids accumulation during long-term anaerobic fermentation of waste activated sludge', Water Research, vol. 155, pp. 142-151.
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© 2019 Elsevier Ltd Cationic polyacrylamide, a flocculation powder widely used in wastewater pretreatment and sludge dewatering, was highly accumulated in waste activated sludge. However, its effect on short-chain fatty acids (SCFAs) accumulation from anaerobic fermentation of waste activated sludge has not been investigated. This work therefore aims to deeply unveil how cationic polyacrylamide affects SCFAs production, through both long-term and batch tests using either real waste activated sludge or synthetic wastewaters as fermentation substrates. Experimental results showed that the presence of cationic polyacrylamide not only significantly decreased the accumulation of SCFAs but also affected the composition of individual SCFA. The concentration of SCFAs decreased from 3374.7 to 2391.7 mg COD/L with cationic polyacrylamide level increasing from 0 to 12 g/kg of total suspended solids, whereas the corresponding percentage of acetic acid increased from 45.2% to 55.5%. The mechanism studies revealed that although cationic polyacrylamide could be partially degraded to produce SCFAs during anaerobic fermentation, cationic polyacrylamide and its major degradation metabolite, polyacrylic acid, inhibited all the sludge solubilization, hydrolysis, acidogenesis, acetogenesis and homoacetogenesis processes to some extents. As a result, the accumulation of SCFAs in the cationic polyacrylamide added systems decreased rather than increased. However, the inhibition to acetogenesis and homoacetogenesis was slighter than that to acidogenesis, leading to an increase of acetic acid to total SCFAs. It was further found that cationic polyacrylamide had stronger ability to adhere to protein molecules surface, which inhibited the bioconversion of proteins more severely. Illumina MiSeq sequencing analyses showed that cationic polyacrylamide decreased microbial community diversity, altered community structure and changed activities of key enzymes responsible for SCFAs accumulation.
Liu, X, Xu, Q, Wang, D, Yang, Q, Wu, Y, Li, Y, Fu, Q, Yang, F, Liu, Y, Ni, B-J, Wang, Q & Li, X 2019, 'Thermal-alkaline pretreatment of polyacrylamide flocculated waste activated sludge: Process optimization and effects on anaerobic digestion and polyacrylamide degradation', Bioresource Technology, vol. 281, pp. 158-167.
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© 2019 Elsevier Ltd Deterioration of anaerobic digestion can occur with the presence of polyacrylamide (PAM) in waste activated sludge, and little information on mitigating this deterioration is currently available. In this study, simultaneous mitigation of PAM negative effects and improvement of methane production was accomplished by thermal-alkaline pretreatment. Under the optimized pretreatment conditions (i.e., 75 °C, pH 11.0 for 17.5 h), the biochemical methane potential of PAM-flocculated sludge increased from 100.5 to 210.8 mL/g VS and the hydrolysis rate increased from 0.122 to 0.187 d−1. Mechanism investigations revealed that the pretreatment not only broke the large firm floccules, improved the degradation of PAM, but also facilitated the release of biodegradable organics from sludge, which thereby provided better growth environment and enough nutrients to anaerobic microbes for methane production. The activities of key enzymes responsible for methane production and PAM degradation were greatly improved in pretreated reactor, with the accumulation of acrylamide being avoided.
Liu, X, Xu, Q, Wang, D, Yang, Q, Wu, Y, Yang, J, Liu, Y, Wang, Q, Ni, B-J, Li, X, Li, H & Yang, G 2019, 'Enhanced Short-Chain Fatty Acids from Waste Activated Sludge by Heat–CaO2 Advanced Thermal Hydrolysis Pretreatment: Parameter Optimization, Mechanisms, and Implications', ACS Sustainable Chemistry & Engineering, vol. 7, no. 3, pp. 3544-3555.
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© 2019 American Chemical Society. In the present work,heat-CaO2 advanced thermal hydrolysis pretreatment was applied for enhancing fermentative short-chain fatty acids (SCFAs) production from waste activated sludge (WAS). Various pretreatment conditions including heating temperatures, CaO2 doses, and times were optimized. Simulation and experimental results showed that the optimal pretreatment conditions were a temperature of 67.4 °C, CaO2 of 0.12 g/g VSS, and time of 19 h, under which the maximum SCFAs yield reached to 336.5 mg COD/g VSS after 5 days of fermentation, with the percentage of acetic acid accounted for 70.1%. Mechanism investigations exhibited that CaO2 and heat pretreatment caused positive synergy on sludge solubilization and SCFAs production. Compared with the control, heat pretreatment, and CaO2 addition alone, the heat-CaO2 pretreatment not only facilitated the organic released from WAS but also increased the proportion of biodegradable organic matters, which thereby providing more organics for subsequent SCFA production. It was found that the heat-CaO2 pretreatment improved the activities of both hydrolytic and acid-forming enzymes while it inhibited the coenzymes of methanogens during the fermentation process. In addition, heat-CaO2 pretreatment and subsequent fermentation worked well in removal of refractory organic pollutants and pathogens contained in WAS. Further analysis indicated that the heat-CaO2 pretreatment can be used as an effective method for both valuable carbon source recovery and refractory pollutant removal in the WAS treatment process.
Liu, Y, Jin, W, Zhou, X, Han, S-F, Tu, R, Feng, X, Jensen, PD & Wang, Q 2019, 'Efficient harvesting of Chlorella pyrenoidosa and Scenedesmus obliquus cultivated in urban sewage by magnetic flocculation using nano-Fe3O4 coated with polyethyleneimine', Bioresource Technology, vol. 290, pp. 121771-121771.
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© 2019 Elsevier Ltd In this work, a novel flocculation process by using nano-Fe3O4 coated with polyethyleneimine (Fe3O4@PEI) as magnetic seeds was developed to harvest the microalgae cultivated in urban sewage. Experiment results indicated that the harvest efficiency of Chlorella pyrenoidosa (0.5 g/L) was 98.92 ± 0.41% under the optimal conditions of Fe3O4@PEI dose of 20 mL/L, flocculation time of 20 min, and stirring speed of 800 rpm (3 min), while that of Scenedesmus obliquus (0.4 g/L) was 98.45 ± 0.35% under a Fe3O4@PEI dose of 16 mL/L, flocculation time of 15 min, and stirring speed of 730 rpm (3 min). Moreover, the process did not reduce the lipid content of microalgae and quality of biodiesel. After microalgae harvest, Fe3O4@PEI could be recovered by ultrasonication, re-wrapped with polyethyleneimine and reused to reduce operational cost.
Liu, Y, Ngo, HH, Guo, W, Peng, L, Wang, D & Ni, B 2019, 'The roles of free ammonia (FA) in biological wastewater treatment processes: A review', Environment International, vol. 123, pp. 10-19.
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© 2018 Free ammonia (FA) can pose inhibitory and/or biocidal effects on a variety of microorganisms involved in different biological wastewater treatment process, which is widely presented in wastewater treatment plants (WWTPs) due to the high levels of ammonium in the systems. This review article gives the up-to-date status on several essential roles of FA in biological wastewater treatment processes: the impacts of FA, mechanisms of FA roles, modeling of FA impacts, and implications of FA for wastewater treatment. Specifically, the impacts of FA on both wastewater and sludge treatment lines were firstly summarized, including nitrification, denitrification, anaerobic ammonium oxidation (Anammox), enhanced biological phosphorus removal and anaerobic processes. The involved mechanisms were then analyzed, which indicated FA inhibition can slow specific microbial activities or even reconfigure the microbial community structure, likely due to negative impacts of FA on intracellular pH, specific enzymes and extracellular polymeric substances (EPS), thus causing cell inactivation/lysis. Mathematical models describing the impact of FA on both wastewater and sludge treatment processes were also explored to facilitate process optimization. Finally, the key implications of FA were identified, that is FA can be leveraged to substantially enhance the biodegradability of secondary sludge, which would further improve biological nutrient removal and enhance renewable energy production.
Liu, Z, Huang, L, Liang, J & Wu, C 2019, 'A three-dimensional indirect boundary integral equation method for modeling elastic wave scattering in a layered half-space', International Journal of Solids and Structures, vol. 169, pp. 81-94.
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© 2019 A new indirect boundary integral equation method (IBIEM)is proposed in this study to solve three-dimensional (3-D)elastic wave scattering by heterogeneities in a multi-layered half-space, employing Green's function of distributed loads on equivalent circular elements, thus avoiding the element discretization on layer interfaces. The proposed method enables the fictitious loads to be directly distributed on the surfaces of scatterer and the weak singularity to be tackled by analytical integration. Also, the radiation condition in the semi-infinite layered medium can be satisfied accurately, and the memory requirements can also be greatly reduced, especially for a large number of layers or gradient medium. The numerical accuracy was verified through comparisons with existing results and the numerical convergence was also confirmed. The results clearly demonstrate the simplicity and effectiveness of the method, and also reveals the complicated scattering characteristics in a layered half-space that are dominated by the resonant properties of the layered medium.
Liu, Z, Yang, C, Gao, W, Wu, D & Li, G 2019, 'Nonlinear behaviour and stability of functionally graded porous arches with graphene platelets reinforcements', International Journal of Engineering Science, vol. 137, pp. 37-56.
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© 2018 Elsevier Ltd This research presents an analytical approach for nonlinear static responses and stability analysis of functionally graded porous (FGP) arches with graphene platelets (GPLs) reinforcements (i.e., FGP-GPLRC arches). The constitutive material composition of the FGP-GPLRC arch varies along the radial direction of the cross section specifically, so that the mechanical performance of the arch such as buckling strength and weight can be well controlled for various engineering design purposes. The effective Young's modulus of the FGP-GPLRC arch is determined by the volume fraction distribution of materials. Based on the Euler-Bernoulli hypothesis, the structural responses of the arch considering the geometric nonlinearity are derived by using the virtual work method. Two boundary conditions are considered which are including the pinned-pinned and the fixed-fixed supports. The loading condition is defined as uniformly distributed load in the radial direction of the arch. Different buckling modes are discussed by the illustration of the equilibrium paths. By adopting the developed analytical solution, the relationship between the structural response, buckling load, self-weight, porosity level and the percentage of content of the GPLs can be investigated efficiently. The applicability and effectiveness of the proposed analytical approach for the geometric nonlinear analysis of FGP-GPLRC arch structures are demonstrated through numerical examples.
Liu, Z, Zhang, H, Cheng, A, Wu, C & Yang, G 2019, 'Seismic Interaction between a Lined Tunnel and a Hill under Plane SV Waves by IBEM', International Journal of Structural Stability and Dynamics, vol. 19, no. 02, pp. 1950004-1950004.
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This paper investigates the dynamic interaction between a lined tunnel and a hill under plane SV waves using the indirect boundary element method (IBEM), with the displacement and stress characteristics of the system presented in frequency domain. The IBEM has several unique advantages such as reducing calculation dimension, automatically satisfying the infinite radiation condition, etc. The numerical results indicated that the dynamic response of the tunnel–hill system is strongly dependent on incident wave characteristics, geometrical and material properties of the lined tunnel, as well as the topography of the hill. For a dimension ratio between the hill and tunnel of less than 10.0, the lined tunnel has large amplification or deamplification effect on the dynamic response of the hill. Correspondingly, the hill also greatly amplifies the displacement and stress concentration of the tunnel especially in the lower-frequency range, due to the complicated interference effect among the reflected waves and diffracted waves induced by the tunnel and hill. Also demonstrated is that the displacement and stress amplitude spectrums highly depend on the incident frequency and the space location, and there exist multiple peaks and troughs in the spectrum curve with the peaks usually appearing in the low-frequency range. Thus, for the seismic safety assessment of a hill slope or hill tunnel in practice, the dynamic interaction within the tunnel–hill system should be taken into consideration.
Long, G, Li, L, Li, W, Ma, K, Dong, W, Bai, C & Zhou, JL 2019, 'Enhanced mechanical properties and durability of coal gangue reinforced cement-soil mixture for foundation treatments', Journal of Cleaner Production, vol. 231, pp. 468-482.
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© 2019 Elsevier Ltd High-speed railways with high load capacity and long-term performance have been developed by the aid of high-performance construction materials for foundation treatments. The mechanical properties and durability of new cement-soil mixture reinforced by local sourced waste coal gangue aggregate were investigated in this study. Extensive experiments were carried out to analyse the effects of coal gangue on compressive strength, elastic modulus, stress-strain curve and anti-corrosion of cement-soil mixture. The results show that incorporation of coal gangue significantly improve the strength, stiffness and anti-corrosion ability of cement-soil mixture. Strength improvements up to 81.8% was achieved, but the ductile failure model shited to brittle failure with more than 42% coal gangue reinforcements. Except for the declining segment of the stress-strain curve, the ascending segment of the stress-strain curve can be fitted by the existing models. From the microstructural characterization, coal gangue can reduce acid solution permeation compared to the soil. For the cemented soil with coal gangue, the mass-loss rates only reach 4–7% after 140 days acid solution immersion. Therefore, this new clean production of high-performance cement-soil mixture through waste coal gangue reinforcement has great potential for railway foundation treatments.
Lu, P, Liu, T, Ni, B-J, Guo, J, Yuan, Z & Hu, S 2019, 'Growth kinetics of Candidatus ‘Methanoperedens nitroreducens’ enriched in a laboratory reactor', Science of The Total Environment, vol. 659, pp. 442-450.
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© 2018 Recently it has been shown that Candidatus ‘Methanoperedens nitroreducens’, an anaerobic methanotrophic archaea (ANME), can reduce nitrate to nitrite using electrons derived from anaerobic oxidation of methane. In this study, the growth kinetics of ‘M. nitroreducens’ enriched in a laboratory reactor were studied. In the experimental concentration range (up to 16 mg CH 4 L −1 ), anaerobic oxidation of methane by ‘M. nitroreducens’ was found to comply with first order kinetic model with a rate constant of 0.019 ± 0.006 h −1 and a biomass-specific rate constant of 0.04–0.14 L h −1 g −1 VSS. Meanwhile, the nitrate reduction to nitrite was well described by the Monod-type kinetic model with an affinity constant for nitrate of 2.1 ± 0.4 mg N L −1 , which is slightly higher than, but comparable to, that of most known denitrifying bacteria. This is the first time that the growth kinetics of ‘M. nitroreducens’ have been experimentally studied. The applicability of the kinetic model reported herein to this organism or similar organisms in natural or engineering systems requires further investigation.
Lu, Z-H, Li, H, Li, W, Zhao, Y-G, Tang, Z & Sun, Z 2019, 'Shear behavior degradation and failure pattern of reinforced concrete beam with chloride-induced stirrup corrosion', Advances in Structural Engineering, vol. 22, no. 14, pp. 2998-3010.
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Reinforcement corrosion exhibits an adverse effect on the shear strength of reinforced concrete structures. In order to investigate the effects of chloride-induced corrosion of reinforcing steel on the shear behavior and failure pattern of reinforced concrete beams, a total of 24 reinforced concrete beams with different concrete strength grades and arrangements of stirrups were fabricated, among which 22 beams were subjected to accelerated corrosion to achieve different degrees of reinforcement corrosion. The failure pattern, crack propagation, load–displacement response, and ultimate strength of these beams were investigated under a standard four-point loading test in this study. Extensive comparative analysis was conducted to investigate the effects of the concrete strength, shear span-to-depth ratio, and stirrup type on the shear behavior of the corroded reinforced concrete beams. The results show that increasing the stirrup yielding strength is more effective in improving the shear strength of corroded reinforced concrete beams than that of concrete compressive strength. In terms of three types of stirrups, the shear strength of the beams with deformed HRB-335 is least sensitive to stirrup corrosion, followed by the beams with smooth HPB-235 and the beams with deformed HRB-400. The effect of the different stirrups on the shear strength depends on the corrosion degree of stirrup and shear span-to-depth ratio of the beam. The predicted results of shear strength of corroded reinforced concrete beams by a proposed analytical model are well consistent with the experimental results.
Lyu, H, Dong, Z, Roobavannan, M, Kandasamy, J & Pande, S 2019, 'Rural unemployment pushes migrants to urban areas in Jiangsu Province, China', Palgrave Communications, vol. 5, no. 1.
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AbstractMigration is often seen as an adaptive human response to adverse socio-environmental conditions, such as water scarcity. A rigorous assessment of the causes of migration, however, requires reliable information on the migration in question and related variables, such as, unemployment, which is often missing. This study explores the causes of one such type of migration, from rural to urban areas, in the Jiangsu province of China. A migration model is developed to fill a gap in the understanding of how rural to urban migration responds to variations in inputs to agricultural production including water availability and labor and how rural population forms expectations of better livelihood in urban areas. Rural to urban migration is estimated at provincial scale for period 1985–2013 and is found to be significantly linked with rural unemployment. Further, migration reacts to a change in rural unemployment after 2–4 years with 1% increase in rural unemployment, on average, leading to migration of 16,000 additional people. This implies that rural population takes a couple of years to internalize a shock in employment opportunities before migrating to cities. The analysis finds neither any evidence of migrants being pulled by better income prospects to urban areas nor being pushed out of rural areas by water scarcity. Corroborated by rural–urban migration in China migration survey data for 2008 and 2009, this means that local governments have 2–4 years of lead time after an unemployment shock, not necessarily linked to water scarcity, in rural areas to prepare for the migration wave in urban areas. This original analysis of migration over a 30-year period and finding its clear link with unemployment, and not with better income in urban areas or poor rainfall, thus provides conclusive evidence in support of policy interventions that focus on generating employment opportunities in rural areas to reduce migration flow to ur...
Ma, C, Li, Q, Zheng, P, Zhou, S, Gao, H, Fang, J & Wang, Y 2019, 'Effects of static eccentricity on the no‐load back electromotive force of external rotor permanent magnet brushless DC motor used as in‐wheel motor', IET Electric Power Applications, vol. 13, no. 5, pp. 604-613.
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© 2019 Institution of Engineering and Technology. All rights reserved. The no-load radial magnetic field and no-load back electromotive force (EMF) of external rotor permanent magnet brushless DC motor (PMBLDCM) are calculated by applying the correction coefficient of magnetic conductance here, taking into account the stator slotting and static eccentricity effects. An external rotor PMBLDCM with 51-slot/46-pole, used as in-wheel motor, is taken as an example, the analytical calculation results of the no-load back EMF are validated by the finite-element method and experiment. The influences of static eccentricity ratio on the no-load radial magnetic field and no-load back EMF are investigated based on the analytical model. The investigation shows that static eccentricity does not change the harmonic contents of no-load radial magnetic field, so it does not change the harmonic contents of three-phase no-load back EMFs. However, static eccentricity changes the space order of no-load radial magnetic field, resulting in the different total harmonic distortions of three-phase no-load back EMFs; in other words, the asymmetric distortions of three-phase no-load back EMFs are generated. The asymmetric distortions of three-phase no-load back EMFs are intensified with the increase in static eccentricity ratio.
Ma, J, Fan, F, Zhang, L, Wu, C & Zhi, X 2019, 'Effect of wave reflection on failure modes of single-layer reticulated domes subjected to interior blast loading', Engineering Failure Analysis, vol. 105, pp. 266-275.
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© 2019 Elsevier Ltd The single-layer reticulated dome is common in public structures, which suggests that this kind of building is a potential target of a terrorist attack. Once this structure is severely damaged in a terrorist attack, the people inside could be seriously injured. To avoid this situation, it is of great significance to investigate the failure mechanisms of the single-layer reticulated domes subjected to blast. In addition, shock waves from a blast converge and propagate in the internal space, leading to a nonuniform blast pressure field on the inner surface of the dome. The effects of reflected waves on failure modes of the dome were systematically investigated. A finite element model of a reticulated dome was created using ANSYS/LS-DYNA, where the code for blast loading that accounted for wave reflection was incorporated. Five failure modes were recognized and defined from 1050 simulations. Regularities in the distributions of failure modes were found. The effects of reflected waves on failure modes were analysed quantificationally.
Ma, J, Fan, F, Zhang, L, Wu, C & Zhi, X 2019, 'Experimental and Numerical Investigations of Pressure Field of Curved Shell Structure Subjected to Interior Blast', Shock and Vibration, vol. 2019, pp. 1-16.
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A terrorist attack on a long-span spatial structure would cause horrible results. Therefore, it is important to determine the characteristics of blast pressure fields to protect such structures. In this study, fully confined blast loading tests were conducted using a rigid curved shell model, which had an inner space similar to that of a reticulated dome. Four different scenarios were carried out to record the blast loading on five typical positions. The blast pressure-time data were compared and analyzed. In addition, a suitable numerical simulation method was proposed for the issues involved in interior blast loading. This numerical model was verified by comparing with the test data. A parametrical analysis of the interior blast simulations was conducted based on this numerical method. The blast loading values at specific positions were obtained with the key parameters varied within a reasonable scope. The blast loading from blast tests and simulations were presented. On this basis, the interior blast loading could conveniently be predicted by using the method and data in this paper, which could be used in the protective design of other reticulated domes.
Ma, XY, Wang, Y, Dong, K, Wang, XC, Zheng, K, Hao, L & Ngo, HH 2019, 'The treatability of trace organic pollutants in WWTP effluent and associated biotoxicity reduction by advanced treatment processes for effluent quality improvement', Water Research, vol. 159, pp. 423-433.
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© 2019 Elsevier Ltd As increasing attention is paid to surface water protection, there has been demand for improvements of domestic wastewater treatment plant (WWTP) effluent. This has led to the application of many different advanced treatment processes (ATPs). In this study, the treatability of trace organic pollutants in secondary effluent (SE) and associated biotoxicity reduction by four types of ATPs, including coagulation, granular activated carbon (GAC) adsorption, ultraviolet (UV) photolysis and photocatalysis, and ozonation, were investigated at the bench-scale. The ATPs showed different removal capacity for the 48 chemicals, which were classified into seven categories. EDCs, herbicides, bactericides and pharmaceuticals were readily degraded, and insecticides, flame retardants, and UV filters were relatively resistant to removal. During these processes, the efficiency of the ATPs in reducing four biological effects were investigated. Of the four biological effects, the estrogenic activity from SE was not detected using the yeast estrogen screen. In contrast with genotoxicity and photosynthesis inhibition, bacterial cytotoxicity posed by SE was the most difficult biological effect to reduce with these ATPs. GAC adsorption and ozonation were the most robust treatment processes for reducing the three detected biotoxicities. UV photolysis and photocatalysis showed comparable efficiencies for the reduction of genotoxicity and photosynthesis inhibition. However, coagulation only performed well in genotoxicity reduction. The effect-based trigger values for the four bioassays, that were derived from the existing environmental quality standards and from HC5 (hazardous concentration for 5% of aquatic organisms), were all used to select and optimize these ATPs for ecological safety. Conducting ATPs in more appropriate ways could eliminate the negative effects of WWTP effluent on receiving water bodies.
Mahanama, D, De Silva, P, Kim, T, Castel, A & Khan, MSH 2019, 'Evaluating Effect of GGBFS in Alkali–Silica Reaction in Geopolymer Mortar with Accelerated Mortar Bar Test', Journal of Materials in Civil Engineering, vol. 31, no. 8, pp. 04019167-04019167.
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Mahdavi, H, Fatahi, B & Khabbaz, H 2019, 'A comparison of frictional and socketed concrete injected columns in a transition zone', Geosynthetics International, vol. 26, no. 5, pp. 497-514.
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This paper sets out to investigate the options available for the transition from Concrete Injected Columns (CICs) to other ground improvement methods, used away from the bridge abutment. Two possible alternatives, widely spaced CICs socketed into stiff material and shorter, closely spaced, frictional CICs, were numerically simulated using FLAC3D software considering the dissipation of porewater pressure and variation of soil permeability with time. The total length of the CICs and the total volume of concrete used for their construction were the same for both alternatives. A geosynthetic layer was introduced into the load transfer platform, and interface elements were incorporated to simulate CIC-soil interaction. The numerical results were also compared with an established analytical solution and a good agreement was achieved. A comparison was then made between the two scenarios; indeed, the embankment on frictional CICs experienced less settlement on the surface, less loads in the geosynthetic, and the bending moments and shear forces generated in the columns were less than the corresponding values for socketed CICs. This study offers an enhanced understanding of the available options to practising engineers when designing road embankments on soft soil.
Mahlia, TMI, Ismail, N, Hossain, N, Silitonga, AS & Shamsuddin, AH 2019, 'Palm oil and its wastes as bioenergy sources: a comprehensive review', Environmental Science and Pollution Research, vol. 26, no. 15, pp. 14849-14866.
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Due to global warming and increasing price of fossil fuel, scientists all over the world have been trying to find reliable alternative fuels. One of the most potential candidates is renewable energy from biomass. The race for renewable energy from biomass has long begun and focused on to combat the deteriorating condition of the environment. Palm oil has been in the spotlight as an alternative of bioenergy sources to resolve fossil fuel problem due to its environment-friendly nature. This review will look deep into the origins of palm oil and how it is processed, bioproducts from this biomass, and oil palm biomass-based power plant in Malaysia. Palm oil is usually processed from oil palm fruits and other parts of the oil palm plant are candidates for raw material of bioproduct generation. Oil palm biomass can be turned into three subcategories: bioproduct, biofuels, and biopower. Focusing on biofuel, the biodiesel from palm oil will be explored in detail and its implication in Malaysia as one of the biggest producers of oil palm in the world will also be emphasized comprehensively. The paper presents the detail of a schematic flow diagram of a palm oil mill process of transforming oil palm into crude palm oil and it wastes. This paper will also discuss the current oil palm biomass power plants in Malaysia. Palm oil has been proven itself as a potential alternative to reduce negative environmental impact of global warming.
Mahlia, TMI, Syaheed, H, Abas, AEP, Kusumo, F, Shamsuddin, AH, Ong, HC & Bilad, MR 2019, 'Organic Rankine Cycle (ORC) System Applications for Solar Energy: Recent Technological Advances', Energies, vol. 12, no. 15, pp. 2930-2930.
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Organic Rankine Cycle (ORC) power generation systems may be used to utilize heat source with low pressure and low temperature such as solar energy. Many researchers have focused on different aspects of ORC power generation systems, but none so far has focused on the patent landscape of ORC system applications. As such, the objective of this study is to identify published patents on ORC system applications, particularly for solar energy. Four (4) technologies were identified in ORC application for solar energy: parabolic dish, parabolic trough, solar tower, and linear Fresnel reflector. A methodical search and analysis of the patent landscape in ORC system applications for solar energy published between 2007–2018 was conducted using the Derwent Innovation patent database. From the approximately 51 million patents in the database from various countries and patent agencies, 3859 patents were initially identified to be related to ORC applications for solar energy. After further stringent selection processes, only 1100 patents were included in this review. From these 1100 patents, approximately 12% (130 patents) are associated with parabolic dishes, about 39% (428 patents) are associated with parabolic troughs, approximately 21% (237 patents) are associated with solar towers, and about 28% (305 patents) are associated with linear Fresnel reflectors. Published patents on solar tower technology are currently on an increasing trend, led by China. All of these patents were published in the past 11 years. From this study, further researches on ORC application are still ongoing, but ORC application for solar energy has the potential to advance; allowing the world to ease issues related to over-reliance on fossil fuel.
Mahmudul, HM, Rasul, MG, Akbar, D & Mofijur, M 2019, 'Opportunities for solar assisted biogas plant in subtropical climate in Australia: A review', Energy Procedia, vol. 160, pp. 683-690.
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© 2019 The Authors. Published by Elsevier Ltd. Household waste generation has become a serious environmental issue in recent years. However, some technologies are available to convert household domestic waste into energy. One of such techniques is the biogas generation using household waste. The biogas generation technique is not a new method of energy generation, but its production efficiency is questionable. Biogas yield from domestic waste are influenced by pH level, temperature, HRT and C/N ratio. Moisture and the temperature levels in the biogas generation systems are very critical to its production efficiency, especially this is highly affected in the colder weather condition. Solar assisted biogas plant may provide better production efficiency compared to the traditionally designed biogas plant. In this paper, the scopes and opportunities of solar assisted biogas generation are reviewed. Possible benefits and challenges associated with the solar assisted biogas generation are highlighted.
Majeed, K, Ahmed, A, Abu Bakar, MS, Indra Mahlia, TM, Saba, N, Hassan, A, Jawaid, M, Hussain, M, Iqbal, J & Ali, Z 2019, 'Mechanical and Thermal Properties of Montmorillonite-Reinforced Polypropylene/Rice Husk Hybrid Nanocomposites', Polymers, vol. 11, no. 10, pp. 1557-1557.
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In recent years, there has been considerable interest in the use of natural fibers as potential reinforcing fillers in polymer composites despite their hydrophilicity, which limits their widespread commercial application. The present study explored the fabrication of nanocomposites by melt mixing, using an internal mixer followed by a compression molding technique, and incorporating rice husk (RH) as a renewable natural filler, montmorillonite (MMT) nanoclay as water-resistant reinforcing nanoparticles, and polypropylene-grafted maleic anhydride (PP-g-MAH) as a compatibilizing agent. To correlate the effect of MMT delamination and MMT/RH dispersion in the composites, the mechanical and thermal properties of the composites were studied. XRD analysis revealed delamination of MMT platelets due to an increase in their interlayer spacing, and SEM micrographs indicated improved dispersion of the filler(s) from the use of compatibilizers. The mechanical properties were improved by the incorporation of MMT into the PP/RH system and the reinforcing effect was remarkable as a result of the use of compatibilizing agent. Prolonged water exposure of the prepared samples decreased their tensile and flexural properties. Interestingly, the maximum decrease was observed for PP/RH composites and the minimum was for MMT-reinforced and PP-g-MAH-compatibilized PP/RH composites. DSC results revealed an increase in crystallinity with the addition of filler(s), while the melting and crystallization temperatures remained unaltered. TGA revealed that MMT addition and its delamination in the composite systems improved the thermal stability of the developed nanocomposites. Overall, we conclude that MMT nanoclay is an effective water-resistant reinforcing nanoparticle that enhances the durability, mechanical properties, and thermal stability of composites.
MANNAN, A, SABRI, MFM, KALAM, MA & MASJUKI, HH 2019, 'Tribological Properties of Steel/Steel, Steel/DLC and DLC/DLC Contacts in the Presence of Biodegradable Oil', Journal of the Japan Petroleum Institute, vol. 62, no. 1, pp. 11-18.
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Mat Nawi, NI, Bilad, MR, Zolkhiflee, N, Nordin, NAH, Lau, WJ, Narkkun, T, Faungnawakij, K, Arahman, N & Mahlia, TMI 2019, 'Development of A Novel Corrugated Polyvinylidene difluoride Membrane via Improved Imprinting Technique for Membrane Distillation', Polymers, vol. 11, no. 5, pp. 865-865.
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Membrane distillation (MD) is an attractive technology for desalination, mainly because its performance that is almost independent of feed solute concentration as opposed to the reverse osmosis process. However, its widespread application is still limited by the low water flux, low wetting resistance and high scaling vulnerability. This study focuses on addressing those limitations by developing a novel corrugated polyvinylidene difluoride (PVDF) membrane via an improved imprinting technique for MD. Corrugations on the membrane surface are designed to offer an effective surface area and at the same time act as a turbulence promoter to induce hydrodynamic by reducing temperature polarization. Results show that imprinting of spacer could help to induce surface corrugation. Pore defect could be minimized by employing a dual layer membrane. In short term run experiment, the corrugated membrane shows a flux of 23.1 Lm−2h−1 and a salt rejection of >99%, higher than the referenced flat membrane (flux of 18.0 Lm−2h−1 and similar rejection). The flux advantage can be ascribed by the larger effective surface area of the membrane coupled with larger pore size. The flux advantage could be maintained in the long-term operation of 50 h at a value of 8.6 Lm−2h−1. However, the flux performance slightly deteriorates over time mainly due to wetting and scaling. An attempt to overcome this limitation should be a focus of the future study, especially by exploring the role of cross-flow velocity in combination with the corrugated surface in inducing local mixing and enhancing system performance.
Maynard-Casely, HE, Booth, N, Leung, AE, Stuart, BH & Thomas, PS 2019, 'Potential of neutron powder diffraction for the study of solid triacylglycerols', Food Structure, vol. 22, pp. 100124-100124.
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© 2019 We present a high-resolution neutron powder diffraction study of the triclinic β form of tripalmitin as well as in situ crystallisation experiments, monitored with neutron diffraction, conducted over three different cooling rates. We use the results from the high-resolution study to anticipate if neutron diffraction could be beneficial in differentiating the polymorphism in triacylglycerol systems. We extend on this to present analysis of a diffraction pattern of cocoa butter, to establish the potential for neutron diffraction to study the (hydrogenous) forms of triacylglycerols used in food production.
Meena, NK & Nimbalkar, S 2019, 'Effect of Water Drawdown and Dynamic Loads on Piled Raft: Two-Dimensional Finite Element Approach', Infrastructures, vol. 4, no. 4, pp. 75-75.
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The piled raft foundations are widely used in infrastructure built on soft soil to reduce the settlement and enhance the bearing capacity. However, these foundations pose a potential risk of failure, if dynamic traffic loading and ground conditions are not adequately accounted in the construction phase. The ground conditions are complex because of frequent groundwater fluctuations. The drawdown of the water table profoundly influences the settlement and load sharing capacity of piled raft foundation. Further, the dynamic loading can also pose a potential risk to these foundations. In this paper, the two-dimensional finite element method (FEM) is employed to analyze the impact of water drawdown and dynamic loading on the stability of piled raft. The seismic response of piled raft is also discussed. The stresses and deformations occurring in and around the raft structure are evaluated. The results demonstrate that water drawdown has a significant effect on the stability and seismic response of piled raft. Various foundation improvement methods are assessed, such as the use of geotextile and increasing thickness of the pile cap, which aids of limiting the settlement.
Meilianda, E, Pradhan, B, Syamsidik, Comfort, LK, Alfian, D, Juanda, R, Syahreza, S & Munadi, K 2019, 'Assessment of post-tsunami disaster land use/land cover change and potential impact of future sea-level rise to low-lying coastal areas: A case study of Banda Aceh coast of Indonesia', International Journal of Disaster Risk Reduction, vol. 41, pp. 101292-101292.
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Melhem, MM, Caprani, CC & Stewart, MG 2019, 'Reliability of Super-T PSC girders at serviceability limit state stresses across all span ranges', Structure and Infrastructure Engineering, vol. 15, no. 6, pp. 812-821.
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Reliability assessment gives useful information on the level of performance or adequacy of design rules. There are five standardized Super-T prestressed concrete (PSC) girder sections widely used for bridges in Australia. The Australian standard (AS 5100) requires serviceability limit state criteria of allowable stresses to be met. However, there is not yet an assessment of the performance achieved by these rules. In this study, all potential strand arrangements (more than 50,000) for all Super-T sections, across all feasible span ranges, are assessed. Ten girder-slab bridge decks are analysed; the critical girder in the deck is designed for all possible strand arrangements. Design adequacy is assessed using the annual reliability index. A system reliability analysis is conducted using Ditlevsen bounds to check that none of the four stress limits are exceeded. Generally, it is found that the Super-T girder designs are adequate for most strand arrangements compliant with AS 5100. Further, the reliability varies significantly depending on the selected span, section and strand arrangement. This work informs designers on the reliability performance of Super-T girders designed to AS 5100 and provides background for future revisions of AS 5100.
Meng, Q, Wu, C, Su, Y, Li, J, Liu, J & Pang, J 2019, 'A study of steel wire mesh reinforced high performance geopolymer concrete slabs under blast loading', Journal of Cleaner Production, vol. 210, pp. 1150-1163.
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© 2018 Elsevier Ltd In this study, a novel green construction material, high performance alkali-activated geopolymer concrete is introduced. Both numerically and experimentally investigations were conducted on a new type of structural slabs made of steel wire mesh reinforced geopolymer concrete against close-in ground surface explosion. Steel rebar reinforced conventional concrete slabs are also studied to compare the results. The experimental investigation was conducted to study the slab damage mechanism. It is found that the steel wire mesh reinforced geopolymer concrete slab showed less damage and fragmentation under 50 kg Trinitrotoluene (TNT) blast load within 3 m, 5 m and 7 m distances as compared to the C30 concrete slab. Numerical analysis was then conducted to further investigate the slab dynamic responses. Combining the steel wire mesh reinforcement with geopolymer concrete can help increase the blast resistance capacity leading to promising and environmental friendly structural protective design.
Meng, Q, Wu, C, Su, Y, Li, J, Liu, J & Pang, J 2019, 'Experimental and numerical investigation of blast resistant capacity of high performance geopolymer concrete panels', Composites Part B: Engineering, vol. 171, pp. 9-19.
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© 2019 Elsevier Ltd In this study, the mechanical properties of a novel high performance alkali-activated geopolymer concrete under both static and dynamic loads were studied. The ground granulated blast-furnace slag powder (GGBS) and silica fume were used to manufacture this geopolymer concrete. Slabs that cast with this geopolymer concrete and steel wire mesh reinforcement were tested under close-in TNT explosion. The steel rebar reinforced C30 concrete slabs were tested as a control group. It is found that the steel wire mesh reinforced geopolymer concrete slabs achieved a more uniform strain distribution, which means a better structural performance against blast loadings as compared to the conventional C30 concrete slab under the same blast loads. The numerical investigation was then conducted to elaborate the test results.
Merenda, A, Kong, L, Fahim, N, Sadek, A, Mayes, ELH, Hawley, A, Zhu, B, Gray, SR & Dumée, LF 2019, 'Sub-10-nm Mixed Titanium/Tantalum Oxide Nanoporous Films with Visible-Light Photocatalytic Activity for Water Treatment', ACS Applied Nano Materials, vol. 2, no. 4, pp. 1951-1963.
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In the present work, anodic mixed titanium/tantalum oxide nanotubes are prepared for the first time with sub-10-nm surface pore size and tube inner diameter. The morphological changes induced by the introduction of Ta into the Ti metal matrix are investigated, leading to remarkable geometrical variations dependent on the Ta loading. The UV-light activation necessary to trigger electron transfer in TiO2 limits the range of applications, and the shift in light absorption toward the visible range represents a significant challenge. Here, the band gaps of the as-created nanotube thin-film arrays are calculated, and the results, showing the presence of a minimum in the band gap, correlated to the presence of titanium and tantalum suboxides and Ta loading. The potential of the thin films as advanced materials for photocatalytic water treatment is tested against that of pure TiO2, and an enhancement in the visible-light absorption and an almost 3-fold increase in the degradation kinetics under pure visible-light irradiation are demonstrated.
Merenda, A, Rana, A, Guirguis, A, Zhu, DM, Kong, L & Dumée, LF 2019, 'Enhanced Visible Light Sensitization of N-Doped TiO2 Nanotubes Containing Ti-Oxynitride Species Fabricated via Electrochemical Anodization of Titanium Nitride', The Journal of Physical Chemistry C, vol. 123, no. 4, pp. 2189-2201.
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The concentration and chemical state of nitrogen represent critical factors to control the band-gap narrowing and the enhancement of visible light harvesting in nitrogen-doped titanium dioxide. In this study, photocatalytic TiO2-N nanoporous structures were fabricated by the electrochemical anodization of titanium nitride sputtered films. Doping was straightforwardly obtained by oxidizing as-sputtered titanium nitride films containing N-metal bonds varying from 7.3 to 18.5% in the Ti matrix. Severe morphological variations into the as-anodized substrates were registered at different nitrogen concentrations and studied by small-angle X-ray scattering. Titanium nitride films with minimum N content of 6.2 atom % N led to a quasi-nanotubular geometry, whereas an increase in N concentration up to 23.8 atom % determined an inhomogeneous, polydispersed distribution of nanotube apertures. The chemical state of nitrogen in the TiO2 matrix was investigated by X-ray photoelectron spectroscopy depth profile analysis and correlated to the photocatalytic performance. The presence of Ti-N and β-Ti substitutional bonds, as well as Ti-oxynitride species was revealed by the analysis of N 1s X-ray photoelectron spectroscopy high-resolution spectra. The minimum N content of 4.1 atom % in the TiO2-N corresponded to the lowest Ti-oxynitride ratio of 13.5%. The relative variation of N-metal bonds was correlated to the visible light sensitization, and the highest Ti-N/Ti oxynitride ratio of 3.3 was attributed to the lowest band gap of 2.7 eV and associated with a 3-fold increase in the degradation of organic dye. Further increase of N doping led to a dramatic drop of Ti-N/Ti oxynitride ratio, from 3.3 to 0.4, which resulted in a loss of photocatalytic activity. The impact of the chemical state of nitrogen toward efficient doping of TiO2 nanotubes is demonstrated with a direct correlation to N loading and a strategy to optimize these factors based on a simple, rapid synthesis from titani...
Merenda, A, Weber, M, Bechelany, M, Allioux, F-M, Hyde, L, Kong, L & Dumée, LF 2019, 'Fabrication of Pd-TiO2 nanotube photoactive junctions via Atomic Layer Deposition for persistent pesticide pollutants degradation', Applied Surface Science, vol. 483, pp. 219-230.
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The design of nano-structured heterogeneous catalytic junctions with high interface to volume ratio and discrete surface distribution is critical to promote the photoelectron activity in the catalytic degradation of organic pollutants. In this work, photocatalytic palladium‑titanium dioxide nano-junctions were fabricated via Atomic Layer Deposition (ALD) of palladium nanoparticles over the surface of titanium dioxide nanotubes. The Pd catalytic interface and resulting active site density was tailored by varying the nanoparticle growth and coalescence via ALD, leading to Pd-TiO 2 junctions with distinctive morphological aspects and interface properties. The visible light response of the Pd-TiO 2 junctions was attributed to the Surface Plasmon Resonance effect and correlated to the variation of the catalyst morphology tuned by ALD. Uniform, discrete distribution of Pd nanoparticles with diameter lower than 5 nm led to high catalytic interface to deposited volume ratio. The nano-engineered Pd-TiO 2 junctions showed enhanced photocatalytic activity towards the degradation of methylene blue selected as a model contaminant and 2,4 D, with a kinetic constant 4.5 higher than as-annealed anatase TiO 2 nanotubes. The design of well-defined catalytic junctions obtainable by a scalable, accurate deposition technique such as ALD represents a promising route to develop cutting-edge photoactive devices with high performance and minimum noble-metal loading.
Mishra, B, Varjani, S, Iragavarapu, GP, Ngo, HH, Guo, W & Vishal, B 2019, 'Microbial Fingerprinting of Potential Biodegrading Organisms', Current Pollution Reports, vol. 5, no. 4, pp. 181-197.
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© 2019, Springer Nature Switzerland AG. The world is witnessing various pollutants in the environment since the last few decades that threaten human life. The biological responses to various pollutants show variations as the living system behaves differently in their sensitivities to the same types of pollutants. The relative response and activity depend upon the duration of exposure to the specific pollutant. It is impossible to stop various activities leading to environmental pollution; however, pollutants can be eliminated from the environment using the microorganisms. Application of biological processes can be executed in order to get rid of toxic pollutants through their biodegradation. The pollutants like hydrocarbons, heavy metals, chlorinated hydrocarbons, nitro-aromatic compounds, non-chlorinated herbicides and pesticides, organophosphates, radionuclides can lead to serious health and environmental problems. The main objective of this paper is to evaluate the effects of pollutants on the living beings and environment, microbial responses to pollution, and distribution of various biodegrading microorganisms in the environment. Profiling of biodegrading microorganisms, microbial biosensor to detect environmental pollution, and strain improvement through genetic manipulation to enhance the biodegradation process have been discussed in detail.
Moayedi, H, Mehrabi, M, Mosallanezhad, M, Rashid, ASA & Pradhan, B 2019, 'Modification of landslide susceptibility mapping using optimized PSO-ANN technique', Engineering with Computers, vol. 35, no. 3, pp. 967-984.
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© 2018, Springer-Verlag London Ltd., part of Springer Nature. In the present study, we applied artificial neural network (ANN) optimized with particle swarm optimization (PSO) for the problem of landslide susceptibility mapping (LSM) prediction. Many studies have revealed that the ANN-based techniques are reliable methods for estimating the LSM. However, most ANN training models facing with major problems such as slow degree of learning system as well as being trapped in their local minima. Optimization algorithms (OA) such as PSO can improve performance results of ANN. Existing applications of PSO model to ANN training have not been used in area of landslide mapping, neither assess the optimal architecture of networks nor the influential factors affecting this problem. Hence, the present study focused on the application of a hybrid PSO-based ANN model (PSO-ANN) to the prediction of landslide susceptibility hazardous mapping. To prepare training and testing datasets for the ANN and PSO-ANN network models, large data collection (i.e., a database consists 168970 training datasets and 42243 testing datasets) were provided from an area of Layleh valley, located in Kermanshah, west of Iran. All the variables of PSO algorithm (e.g., in addition to the network parameter and network weights) were optimized to achieve the most reliable maps of landslide susceptibility. The input dataset includes elevation, slope aspect, slope degree, curvature, soil type, lithology, distance to road, distance to river, distance to fault, land use, stream power index (SPI) and topographic wetness index (TWI), where the output was taken landslide susceptibility value. The predicted results (e.g., from ANN, PSO-ANN) for both of datasets (e.g., training and testing) of the models were assessed based on two statistical indices namely, coefficient of determination (R2) and root-mean-squared error (RMSE). In this study, to evaluate the ability of all methods, color intensity rating (CE...
Moayedi, H, Tien Bui, D, Gör, M, Pradhan, B & Jaafari, A 2019, 'The Feasibility of Three Prediction Techniques of the Artificial Neural Network, Adaptive Neuro-Fuzzy Inference System, and Hybrid Particle Swarm Optimization for Assessing the Safety Factor of Cohesive Slopes', ISPRS International Journal of Geo-Information, vol. 8, no. 9, pp. 391-391.
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In this paper, a neuro particle-based optimization of the artificial neural network (ANN) is investigated for slope stability calculation. The results are also compared to another artificial intelligence technique of a conventional ANN and adaptive neuro-fuzzy inference system (ANFIS) training solutions. The database used with 504 training datasets (e.g., a range of 80%) and testing dataset consists of 126 items (e.g., 20% of the whole dataset). Moreover, variables of the ANN method (for example, nodes number for each hidden layer) and the algorithm of PSO-like swarm size and inertia weight are improved by utilizing a total of 28 (i.e., for the PSO-ANN) trial and error approaches. The key properties were fed as input, which were utilized via the analysis of OptumG2 finite element modelling (FEM), containing undrained cohesion stability of the baseline soil (Cu), angle of the original slope (β), and setback distance ratio (b/B) where the target is selected factor of safety. The estimated data for datasets of ANN, ANFIS, and PSO-ANN models were examined based on three determined statistical indexes. Namely, root mean square error (RMSE) and the coefficient of determination (R2). After accomplishing the analysis of sensitivity, considering 72 trials and errors of the neurons number, the optimized architecture of 4 × 6 × 1 was determined to the structure of the ANN model. As an outcome, the employed methods presented excellent efficiency, but based on the ranking method, the PSO-ANN approach might have slightly better efficiency in comparison to the algorithms of ANN and ANFIS. According to statistics, for the proper structure of PSO-ANN, the indexes of R2 and RMSE values of 0.9996, and 0.0123, as well as 0.9994 and 0.0157, were calculated for the training and testing networks. Nevertheless, having the ANN model with six neurons for each hidden layer was formulized for further practical use. This study demonstrates the efficiency of the proposed neu...
Mofijur, M, Hasan, MM, Mahlia, TMI, Rahman, SMA, Silitonga, AS & Ong, HC 2019, 'Performance and Emission Parameters of Homogeneous Charge Compression Ignition (HCCI) Engine: A Review', Energies, vol. 12, no. 18, pp. 3557-3557.
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Strict emission regulations and demand for better fuel economy are driving forces for finding advanced engines that will be able to replace the conventional internal combustion engines in the near future. Homogeneous charge compression ignition (HCCI) engines use a different combustion technique; there are no spark plugs or injectors to assist the combustion. Instead, when the mixtures reach chemical activation energy, combustion auto-ignites in multiple spots. The main objective of this review paper is to study the engine performance and emission characteristics of HCCI engines operating in various conditions. Additionally, the impact of different fuels and additives on HCCI engine performance is also evaluated. The study also introduces a potential guideline to improve engine performance and emission characteristics. Compared to conventional compression ignition and spark ignition combustion methods, the HCCI combustion mode is noticeably faster and also provides better thermal efficiency. Although a wide range of fuels including alternative and renewable fuels can be used in the HCCI mode, there are some limitation/challenges, such as combustion limited operating range, phase control, high level of noise, cold start, preparation of homogeneous charge, etc. In conclusion, the HCCI combustion mode can be achieved in existing spark ignition (SI) engines with minor adjustments, and it results in lower oxides of nitrogen (NOx) and soot emissions, with practically a similar performance as that of SI combustion. Further improvements are required to permit extensive use of the HCCI mode in future.
Mofijur, M, Mahlia, T, Silitonga, A, Ong, H, Silakhori, M, Hasan, M, Putra, N & Rahman, SM 2019, 'Phase Change Materials (PCM) for Solar Energy Usages and Storage: An Overview', Energies, vol. 12, no. 16, pp. 3167-3167.
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Solar energy is a renewable energy source that can be utilized for different applications in today’s world. The effective use of solar energy requires a storage medium that can facilitate the storage of excess energy, and then supply this stored energy when it is needed. An effective method of storing thermal energy from solar is through the use of phase change materials (PCMs). PCMs are isothermal in nature, and thus offer higher density energy storage and the ability to operate in a variable range of temperature conditions. This article provides a comprehensive review of the application of PCMs for solar energy use and storage such as for solar power generation, water heating systems, solar cookers, and solar dryers. This paper will benefit the researcher in conducting further research on solar power generation, water heating system, solar cookers, and solar dryers using PCMs for commercial development.
Mofijur, M, Rasul, M, Hassan, NMS & Uddin, MN 2019, 'Investigation of exhaust emissions from a stationary diesel engine fuelled with biodiesel', Energy Procedia, vol. 160, pp. 791-797.
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© 2019 The Authors. Published by Elsevier Ltd. This paper studied the production of waste cooking biodiesel as an alternative fuel for diesel engine. The biodiesel was produced through conventional transesterification process using the base catalyst (KOH). A multi-cylinder diesel engine was used to evaluate the emission of 20% (B20) waste cooking biodiesel fuel at different engine speeds and full load condition. It was found that the characteristics of biodiesel are within the limit of specified standards (American Society for Testing and Materials, ASTM D6751) and comparable to diesel fuel. Engine emission results indicated that waste cooking biodiesel fuel sample reduces the average carbon monoxide (CO) and particulate matter (PM) emissions except nitrogen oxides (NOx) than diesel fuel. Finally, it can be concluded that 20% of waste cooking biodiesel can significantly contribute to lower the harmful emission of an unmodified stationary diesel engine to the environment.
Mofijur, M, Rasul, MG, Hassan, NMS & Nabi, MN 2019, 'Recent Development in the Production of Third Generation Biodiesel from Microalgae', Energy Procedia, vol. 156, pp. 53-58.
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© 2019 The Authors. Published by Elsevier Ltd. Increasing global energy demand at a rate faster than the population growth has led the researcher to look for alternative fuel. Amongst the options, biodiesel is an environmentally sustainable substitute of diesel fuel being renewable, biodegradable and have similar properties of fossil diesel. Among the biodiesel sources, microalgae is a potential third generation biodiesel feedstock which can be produced throughout the year and its oil yield is higher than any other crops. This paper reviews recent development in microalgae biodiesel in terms of its oil extraction technics, challenges of oil extraction, production of biodiesel from microalgae oil and its fuel properties. Finally, the paper discusses the performance and combustion analysis of diesel engine fuelled with microalgae biodiesel. This paper provides a clear understanding of the potential use of microalgae biodiesel as an alternative source to fossil diesel for diesel engines.
Mofijur, Mahlia, Logeswaran, Anwar, Silitonga, Rahman & Shamsuddin 2019, 'Potential of Rice Industry Biomass as a Renewable Energy Source', Energies, vol. 12, no. 21, pp. 4116-4116.
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Fossil fuel depletion, along with its ever-increasing price and detrimental impact on the environment, has urged researchers to look for alternative renewable energy. Of all the options available, biomass presents a very reliable source due to its never-ending supply. As research on various biomasses has grown in recent years, waste from these biomasses has also increased, and it is now time to shift the focus to utilizing these wastes for energy. The current waste management system mainly focuses on open burning and soil incorporation as it is cost-effective; however, these affect the environment. There must be an alternative way, such as to use it for power generation. Rice straw and rice husk are examples of such potential biomass waste. Rice is the main food source for the world, mostly in Asian regions, as most people consume rice daily. This paper reviews factors that impact the implementation of rice-straw-based power plants. Ash content and moisture content are important properties that govern combustion, and these vary with location. Logistical improvements are required to reduce the transport cost of rice husk and rice straw, which is higher than the transportation cost of coal.
Moghaddam, F, Sirivivatnanon, V & Vessalas, K 2019, 'The effect of fly ash fineness on heat of hydration, microstructure, flow and compressive strength of blended cement pastes', Case Studies in Construction Materials, vol. 10, pp. e00218-e00218.
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© 2019 In this paper, an experimental study on the effect of fly ash fineness on the heat of hydration, microstructure, flow and compressive strength of blended cement pastes was carried out and evaluated against control cement paste. Fly ashes with different fineness: classified fly ash, run-of-station fly ash and grounded run-of-station fly ash; with a median particle size of 17.4, 11.3 and 5.7 μm, respectively, from the same power station source in Australia were used to partially replace Portland cement at 20% and 40% by weight of cement using a fixed water-to-binder ratio of 0.40. Results of this study showed that the cumulative heat of hydration of blended cement paste decreased as fly ash content in blended cement paste was increased. For a given cement replacement level, blended cement paste containing finer fly ash released more heat of hydration when compared to coarser fly ash. Moreover, increasing the fineness of fly ash resulted in a higher consumption of calcium hydroxide at 7 and 28 days reflecting pozzolanic reactivity and, thus, a denser microstructure than blended pastes containing coarser fly ash as revealed by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and compressive strength results. In addition, the incorporation of fly ash in the blended pastes led to the introduction of an additional hydration peak in the heat evolution curve possibly due to the late activation of fly ash by calcium hydroxide renewing the C 3 A reaction and converting ettringite to monosulfate. The flow of the freshly blended cement pastes was also found to improve slightly with increasing fineness of the fly ash. In addition, the hardened blended cement pastes containing 20% ground run-of-station fly ash showed comparable compressive strength with the control cement pastes at both 7 and 28 days mainly due to the higher fineness of the ground run-of-station fly ash and increased reactivity compared to coarser grade fly ash.
Mohammadinia, A, Saeidian, B, Pradhan, B & Ghaemi, Z 2019, 'Prediction mapping of human leptospirosis using ANN, GWR, SVM and GLM approaches', BMC Infectious Diseases, vol. 19, no. 1.
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Abstract Background Recent reports of the National Ministry of Health and Treatment of Iran (NMHT) show that Gilan has a higher annual incidence rate of leptospirosis than other provinces across the country. Despite several efforts of the government and NMHT to eradicate leptospirosis, it remains a public health problem in this province. Modelling and Prediction of this disease may play an important role in reduction of the prevalence. Methods This study aims to model and predict the spatial distribution of leptospirosis utilizing Geographically Weighted Regression (GWR), Generalized Linear Model (GLM), Support Vector Machine (SVM) and Artificial Neural Network (ANN) as capable approaches. Five environmental parameters of precipitation, temperature, humidity, elevation and vegetation are used for modelling and predicting of the disease. Data of 2009 and 2010 are used for training, and 2011 for testing and evaluating the models. Results Results indicate that utilized approaches in this study can model and predict leptospirosis with high significance level. To evaluate the efficiency of the approaches, MSE (GWR = 0.050, SVM = 0.137, GLM = 0.118 and ANN = 0.137), MAE (0.012, 0.063, 0.052 and 0.063), MRE (0.011, 0.018, 0.017 and 0.018) and R2 (0.85, 0.80, 0.78 and 0.75) are used. Conclusion Results indicate the practical usefulness of approaches for spatial modelling and predicting leptospirosis. The efficiency of models is as follow: GWR > SVM > GLM...
Mojaddadi Rizeei, H, Pradhan, B & Saharkhiz, MA 2019, 'Urban object extraction using Dempster Shafer feature-based image analysis from worldview-3 satellite imagery', International Journal of Remote Sensing, vol. 40, no. 3, pp. 1092-1119.
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© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. A detailed and up-to-date land use of the urban environment is essentially required in many applications. Very high-resolution (VHR), Multispectral Scanner System (MSS) Worldview-3 (WV-3) satellite imagery provides detailed information on urban characteristics, which should be professionally mined. In this research, WV-3 was processed by machine learning (ML) methods to extract the most accurate urban features. Fuze-Go panchromatic sharpening in conjunction with atmospheric and topographic correction was initially utilized to increase the image quality and colour contrast. Three image analysis approaches including, current pixel-based image analysis (PBIA), object-based image analysis (OBIA) and new feature-based image analysis (FBIA) were implemented on WV-3 image. The k-nearest neighbour (k-NN), Naive Bayes (NB), support vector machine (SVM) classifiers were represented by PBIA, the Decision Tree (DT) classifier was examined as OBIA and the Dempster–Shafer (DS) fusion classifier was manifested for the first time as FBIA. In order to engage DS as FBIA, four types of Belief Masses, namely, Precision, Recall, Overall Accuracy, and kappa coefficient (ĸ) were implemented and compared to assign the most likelihood urban features. All the applied classifiers were also trained on the first site and then tested on another site to examine the transferability. The accuracy, reliability, and computational time of all classifiers were examined by confusion matrix and McNemar assessment. Results show improvements on the detailed urban extraction obtained using the proposed FBIA with 92.2% overall accuracy in compared with PBIA and OBIA. The FBIA result of urban extraction is more consistent when transferred to another study area and consumes much lesser time than OBIA. Also, the precision mass belief measurement achieved highest efficiency regarding receiver operating characteristic (ROC) curve rate.
Mojiri, A, Zhou, JL, Ohashi, A, Ozaki, N & Kindaichi, T 2019, 'Comprehensive review of polycyclic aromatic hydrocarbons in water sources, their effects and treatments', Science of The Total Environment, vol. 696, pp. 133971-133971.
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© 2019 Elsevier B.V. Polycyclic aromatic hydrocarbons (PAHs) are principally derived from the incomplete combustion of fossil fuels. This study investigated the occurrence of PAHs in aquatic environments around the world, their effects on the environment and humans, and methods for their removal. Polycyclic aromatic hydrocarbons have a great negative impact on the humans and environment, and can even cause cancer in humans. Use of good methods and equipment are essential to monitoring PAHs, and GC/MS and HPLC are usually used for their analysis in aqueous solutions. In aquatic environments, the PAHs concentrations range widely from 0.03 ng/L (seawater; Southeastern Japan Sea, Japan) to 8,310,000 ng/L (Domestic Wastewater Treatment Plant, Siloam, South Africa). Moreover, bioaccumulation of ∑16PAHs in fish has been reported to range from 11.2 ng/L (Cynoscion guatucupa, South Africa) to 4207.5 ng/L (Saurida undosquamis, Egypt). Several biological, physical and chemical and biological techniques have been reported to treat water contaminated by PAHs, but adsorption and combined treatment methods have shown better removal performance, with some methods removing up to 99.99% of PAHs.
Moni, MA, Rana, HK, Islam, MB, Ahmed, MB, Xu, H, Hasan, MAM, Lei, Y & Quinn, JMW 2019, 'A computational approach to identify blood cell-expressed Parkinson's disease biomarkers that are coordinately expressed in brain tissue', Computers in Biology and Medicine, vol. 113, pp. 103385-103385.
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Motevalli, A, Naghibi, SA, Hashemi, H, Berndtsson, R, Pradhan, B & Gholami, V 2019, 'Inverse method using boosted regression tree and k-nearest neighbor to quantify effects of point and non-point source nitrate pollution in groundwater', Journal of Cleaner Production, vol. 228, pp. 1248-1263.
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© 2019 Elsevier Ltd Nitrate pollution of groundwater has increased dramatically worldwide due to increase of population and agricultural productivity. The resulting nitrate concentration in groundwater is usually a combination of various types of point and non-point pollutant sources. It is often difficult to distinguish between these sources since groundwater is formed in large and complex catchments with various natural processes and anthropogenic influence that contribute to a certain downstream nitrate concentration. For such conditions, this paper uses a methodology that can be used to inversely determine type and location of main nitrate pollutant source. The methodology builds on two state-of-the-art data mining techniques, boosted regression tree (BRT)and k-nearest neighbor (KNN). These techniques are used to produce a nitrate pollution vulnerability map. The methodology can mitigate effects of subjective judgement on determining importance of different sources and mechanisms for nitrate transport. The investigated mechanisms are hydrogeological, hydrological, anthropogenic, topography, and soil conditioning factors. Thus, the proposed methodology is used to separate between natural processes and anthropogenic effects on nitrate pollution. To calculate the groundwater vulnerability maps, a groundwater nitrate concentration of 40 mg/L (suggested by WHO with a 20% risk margin)was selected as a general threshold for identifying polluted areas that resulted in 96 polluted wells. Non-polluted locations were selected from well data with nitrate concentration less than 15 mg/L (96 non-polluted). The models were trained on 70% polluted and 70% non-polluted site data. The remaining data, 30% polluted and 30% non-polluted sites, were used to validate the simulation results. Results showed that the BRT produced outputs with higher performance than the KNN algorithm. The final ranking results based on the BRT model showed the higher importance of hydraulic ...
Naderpour, M, Rizeei, HM, Khakzad, N & Pradhan, B 2019, 'Forest fire induced Natech risk assessment: A survey of geospatial technologies', Reliability Engineering & System Safety, vol. 191, pp. 106558-106558.
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© 2019 Elsevier Ltd Forest fires threaten a large part of the world's forests, communities, and industrial plants, triggering technological accidents (Natechs). Forest fire modelling with respect to contributing spatial parameters is one of the well-known ways not only to predict the fire occurrence in forests, but also to assess the risk of forest-fire-induced Natechs. This study is a review of methods based on geospatial information system (GIS) for modelling forest fires and their potential Natechs that have been implemented all over the world. The present study conducts a systematic literature review of the methods used for forest fire susceptibility, hazard, and risk assessment, while dividing them into four general categories: (a) statistical and data-driven models; (b) machine learning models; (c) multi-criteria decision-making models, and (d) ensemble models. In addition, some forest fire detection techniques using satellite imagery are reviewed. A comparison is also conducted to highlight the research gaps and required future research. The results of the present research assist decision makers to select the most appropriate techniques according to specific forest conditions. Results show that data-driven approaches are the most frequently applied methods while ensemble approaches are more accurate.
Naghibi, SA, Dolatkordestani, M, Rezaei, A, Amouzegari, P, Heravi, MT, Kalantar, B & Pradhan, B 2019, 'Application of rotation forest with decision trees as base classifier and a novel ensemble model in spatial modeling of groundwater potential', Environmental Monitoring and Assessment, vol. 191, no. 4.
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© 2019, Springer Nature Switzerland AG. Groundwater resources are facing a high pressure due to drought and overexploitation. The main aim of this research is to apply rotation forest (RTF) with decision trees as base classifiers and an improved ensemble methodology based on evidential belief function and tree-based models (EBFTM) for preparing groundwater potential maps (GPM). The performance of these new models is then compared with three previously implemented models, i.e., boosted regression tree (BRT), classification and regression tree (CART), and random forest (RF). For this purpose, spring locations in the Meshgin Shahr in Iran were detected. The spring locations were randomly categorized into training (70% of the locations) and validation (30% of the locations) datasets. Furthermore, several groundwater conditioning factors (GCFs) such as hydrogeological, topographical, and land use factors were mapped and regarded as input variables. The tree-based algorithms (i.e., BRT, CART, RF, and RTF) were applied by implementing the input variables and training dataset. The groundwater potential values (i.e., spring occurrence probability) obtained by the BRT, CART, RF, and RTF models for all the pixels of the study area were classified into four potential classes and then used as inputs of the EBF model to construct the new ensemble model (i.e., EBFTM). At last, this paper implemented a receiver operating characteristics (ROC) curve for determining the efficiency of the EBFTM, RTF, BRT, CART, and RF methods. The findings illustrated that the EBFTM had the highest efficacy with an area under the ROC curve (AUC) of 90.4%, followed by the RF, BRT, CART, and RTF models with AUC-ROC values of 90.1, 89.8, 86.9, and 86.2%, respectively. Thus, it could be inferred that the ensemble approach is capable of improving the efficacy of the single tree-based models in GPM production.
Naidu, G, Ryu, S, Thiruvenkatachari, R, Choi, Y, Jeong, S & Vigneswaran, S 2019, 'A critical review on remediation, reuse, and resource recovery from acid mine drainage', Environmental Pollution, vol. 247, pp. 1110-1124.
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© 2019 Elsevier Ltd Acid mine drainage (AMD) is a global environmental issue. Conventionally, a number of active and passive remediation approaches are applied to treat and manage AMD. Case studies on remediation approaches applied in actual mining sites such as lime neutralization, bioremediation, wetlands and permeable reactive barriers provide an outlook on actual long-term implications of AMD remediation. Hence, in spite of available remediation approaches, AMD treatment remains a challenge. The need for sustainable AMD treatment approaches has led to much focus on water reuse and resource recovery. This review underscores (i) characteristics and implication of AMD, (ii) remediation approaches in mining sites, (iii) alternative treatment technologies for water reuse, and (iv) resource recovery. Specifically, the role of membrane processes and alternative treatment technologies to produce water for reuse from AMD is highlighted. Although membrane processes are favorable for water reuse, they cannot achieve resource recovery, specifically selective valuable metal recovery. The approach of integrated membrane and conventional treatment processes are especially promising for attaining both water reuse and recovery of resources such as sulfuric acid, metals and rare earth elements. Overall, this review provides insights in establishing reuse and resource recovery as the holistic approach towards sustainable AMD treatment. Finally, integrated technologies that deserve in depth future exploration is highlighted. Challenges associated with AMD can be sustainability addressed through integrated treatment approaches that attain both water reuse and valuable resource recovery.
Nasruddin, Sholahudin, Satrio, P, Mahlia, TMI, Giannetti, N & Saito, K 2019, 'Optimization of HVAC system energy consumption in a building using artificial neural network and multi-objective genetic algorithm', Sustainable Energy Technologies and Assessments, vol. 35, pp. 48-57.
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© 2019 Elsevier Ltd The optimization of heating, ventilating and air conditioning (HVAC) system operations and other building parameters intended to minimize annual energy consumption and maximize the thermal comfort is presented in this paper. The combination of artificial neural network (ANN) and multi-objective genetic algorithm (MOGA) is applied to optimize the two-chiller system operation in a building. The HVAC system installed in the building integrates radiant cooling system, variable air volume (VAV) chiller system, and dedicated outdoor air system (DOAS). Several parameters including thermostat setting, passive solar design, and chiller operation control are considered as decision variables. Subsequently, the percentage of people dissatisfied (PPD) and annual building energy consumption is chosen as objective functions. Multi-objective optimization is employed to optimize the system with two objective functions. As the result, ANN performed a good correlation between decision variables and the objective function. Moreover, MOGA successfully provides several alternative possible design variables to achieve optimum system in terms of thermal comfort and annual energy consumption. In conclusion, the optimization that considers two objectives shows the best result regarding thermal comfort and energy consumption compared to base case design.
Ngo, HH, Guo, W & Boopathy, R 2019, 'Editorial overview: Green technologies for environmental remediation', Current Opinion in Environmental Science & Health, vol. 12, pp. A1-A3.
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Ngo, TN, Indraratna, B & Rujikiatkamjorn, C 2019, 'Improved performance of ballasted tracks under impact loading by recycled rubber mats', Transportation Geotechnics, vol. 20, pp. 100239-100239.
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© 2019 Elsevier Ltd Ballasted tracks at transition locations such as approaches to bridges and road crossings experience increasing degradation and deformation due to dynamic and high impact forces, a key factor that decreases the stability and longevity of railroads. One solution to minimise ballast degradation at the transition zones is using rubber energy absorbing drainage sheets (READS)manufactured from recycled tyres. When placed beneath the ballast layer, READS distributes the load over wider area and attenuate of the load over a longer duration thus decreasing maximum stress, apart from reducing the energy transferred to the ballast and other substructure components. Subsequently, the track substructure experiences less plastic deformation and degradation. These mats also provide an environmentally friendly and cost-effective alternative. In this study, a series of large-scale drop hammer impact tests was carried out to investigate how effectively the READS could attenuate impact loads and help mitigate ballast deformation and degradation. Soft and stiff subgrade were used to investigate the load-deformation response of ballast (with and without READS), subjected to impact loads from a hammer dropped from various heights (hd = 100–250 mm). Laboratory test results show that the inclusion of READS helps to reduce the dynamic impact load transferred to the ballast layer resulting in significantly less permanent deformation and degradation of ballast, apart from significant attenuation of load magnitude and vibration to the underlying subgrade layers.
Ngoc, TP, Fatahi, B & Khabbaz, H 2019, 'Impacts of Drying-Wetting and Loading-Unloading Cycles on Small Strain Shear Modulus of Unsaturated Soils', International Journal of Geomechanics, vol. 19, no. 8, pp. 04019090-04019090.
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© 2019 American Society of Civil Engineers. The small strain shear modulus (Gmax) is an important parameter in geodynamic problems. To predict the Gmax of unsaturated soils that are normally subjected to complex drying and wetting processes, the effect of hydraulic hysteresis needs to be evaluated. Although several equations have been proposed in recent years, limitations still exist, requiring more research studies in this field. In this study, Gmax was investigated in a multistage test during several drying-wetting cycles and a loading-unloading cycle of net stress. The results revealed four key factors that directly influence the magnitude of Gmax: the void ratio, net stress, matric suction, and degree of saturation. Although variations of the void ratio, net stress, and matric suction cause persistent responses of Gmax (i.e., if all other factors remain unchanged, Gmax would then be reversely proportional to the void ratio and directly proportional to the net stress and matric suction), variations in the degree of saturation result in different responses. A decrease in the degree of saturation may induce a reduction or growth of Gmax because, on the one hand, it reduces the effect of matric suction, whereas on the other hand, it increases the total effect of van der Waals attractions and electric double-layer repulsions. At the same stress state, a reverse trend, induced by an increase in the degree of saturation, will occur with a growth in the effect of matric suction and a reduction in the combined effect of van der Waals attractions and electric double-layer repulsions. An analysis of the results showed that hydraulic hysteresis occurred in all the stress loops, and it directly influenced the response of Gmax. The effect of hydraulic hysteresis can only be captured if the van der Waals attractions and electric double-layer repulsions are considered. A model to estimate Gmax while incorporating the van der Waals attractions and electric double-la...
Nguyen, AQ, Nguyen, LN, Phan, HV, Galway, B, Bustamante, H & Nghiem, LD 2019, 'Effects of operational disturbance and subsequent recovery process on microbial community during a pilot-scale anaerobic co-digestion', International Biodeterioration & Biodegradation, vol. 138, pp. 70-77.
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© 2019 This study investigated changes in microbial community structure and composition in response to operational disturbance and subsequent process recovery by inoculum addition. Amplicon sequencing of 16S rRNA and mcrA marker genes on the Illumina Miseq platform was used for microbial community analysis. The results show that imbalance among core microbial groups caused volatile fatty acid accumulation and subsequent deteriorated biogas production (decreased by 45% of daily volume) and methane content (<49%). Operational disturbance led to the enrichment of hydrolytic and fermentative bacteria (accounted for >57% of the total abundance) and reduction of acetogenic and methanogenic microbes (they accounted for <9% and <3% of the total abundance, respectively). Acetogens and methanogens were replenished by inoculum addition to recover digester performance. Although digester performances were similar in stable (prior to disturbance) and post recovery phases, the microbial community did not return to the original state, suggesting the existence of functional redundancy in the community.
Nguyen, DD, Jeon, B-H, Jeung, JH, Rene, ER, Banu, JR, Ravindran, B, Vu, CM, Ngo, HH, Guo, W & Chang, SW 2019, 'Thermophilic anaerobic digestion of model organic wastes: Evaluation of biomethane production and multiple kinetic models analysis', Bioresource Technology, vol. 280, pp. 269-276.
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© 2019 Elsevier Ltd The main aim of this work was to test various organic wastes, i.e. from a livestock farm, a cattle slaughterhouse and agricultural waste streams, for its ability to produce methane under thermophilic anaerobic digestion (AD) conditions. The stability of the digestion, potential biomethane production and biomethane production rate for each waste were assessed. The highest methane yield (110.83 mL CH4/g VSadded day) was found in the AD of crushed animal carcasses on day 4. The experimental results were analyzed using four kinetic models and it was observed that the Cone model described the biomethane yield as well as the methane production rate of each substrate. The results from this study showed the good potential of model organic wastes to produce biomethane.
Nguyen, HH, Khabbaz, H & Fatahi, B 2019, 'A numerical comparison of installation sequences of plain concrete rigid inclusions', Computers and Geotechnics, vol. 105, pp. 1-26.
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© 2018 Elsevier Ltd Soil displacement induced when installing controlled modulus columns (CMC) as ground reinforcement could affect the columns installed close by. Realising numerical analyses may provide useful insights, this paper describes a numerical approach to investigate how groups of CMC installed in different sequences could affect columns installed previously. Coupled consolidation analyses in large strain mode and incorporating soil-CMC interaction were carried out using the three-dimensional finite difference software package FLAC3D. The CMCs were modelled using advanced non-linear Hoek-Brown material with a tensile yield criterion while soils with a typical profile were characterised using the modified Cam Clay and the elastic-perfectly plastic material with a Mohr-Coulomb yield criterion. Where possible, the predicted responses of ground surrounding the CMCs were compared to a number of existing analytical methods. Predictions revealed that lateral soil movement and soil heave near existing CMCs induced by installing new CMCs towards the existing CMCs were approximately 15% and 25% greater than corresponding predictions when a reverse installation sequence was adopted. The maximum excess pore water pressures, induced near existing columns due to installing new columns towards the existing ones, were almost twice more than those caused by the reverse sequence of installation. Moreover, the predicted bending moments generated in the existing columns induced by installing new columns towards the existing CMCs were almost 22% greater than the corresponding values when the reverse installation sequence was adopted. This shows the importance of selecting an appropriate installation sequence in the CMC construction process as well as considering the initial stress field and bending moments in the surrounding soil and CMCs, respectively when designing embankments on improved soft soils.
Nguyen, HTH, Sakakibara, M, Nguyen, MN, Mai, NT & Nguyen, VT 2019, 'Effect of Dissolved Silicon on the Removal of Heavy Metals from Aqueous Solution by Aquatic Macrophyte Eleocharis acicularis', Water, vol. 11, no. 5, pp. 940-940.
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Silicon (Si) has been recently reconsidered as a beneficial element due to its direct roles in stimulating the growth of many plant species and alleviating metal toxicity. This study aimed at validating the potential of an aquatic macrophyte Eleocharis acicularis for simultaneous removal of heavy metals from aqueous solutions under different dissolved Si. The laboratory experiments designed for determining the removal efficiencies of heavy metals were conducted in the absence or presence of Si on a time scale up to 21 days. Eleocharis acicularis was transplanted into the solutions containing 0.5 mg L−1 of indium (In), gallium (Ga), silver (Ag), thallium (Tl), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) with various Si concentrations from 0 to 4.0 mg L−1. The results revealed that the increase of dissolved Si concentrations enhanced removal efficiencies of E. acicularis for Ga, Cu, Zn, Cd, and Pb, while this increase did not show a clear effect for In, Tl, and Ag. Our study presented a notable example of combining E. acicularis with dissolved Si for more efficient removals of Cu, Zn, Cd, Pb, and Ga from aqueous solutions. The findings are applicable to develop phytoremediation or phytomining strategy for contaminated environment.
Nguyen, KT, Nguyen, HM, Truong, CK, Ahmed, MB, Huang, Y & Zhou, JL 2019, 'Chemical and microbiological risk assessment of urban river water quality in Vietnam', Environmental Geochemistry and Health, vol. 41, no. 6, pp. 2559-2575.
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© 2019, Springer Nature B.V. Abstract: The contamination and risk by nutrients (NH4+, NO2−, NO3− and PO43−), COD, BOD5, coliform and potentially toxic elements (PTEs) of As, Cd, Ni, Hg, Cu, Pb, Zn and Cr were investigated in urban river (Nhue River), Vietnam during 2010–2017. The extensive results demonstrated that concentrations of these contaminants showed significant spatial and temporal variations. The Nhue River was seriously polluted by NH4+ (0.025–11.28 mg/L), PO43− (0.17–1.72 mg/L), BOD5 (5.8–179.6 mg/L), COD (1.4–239.8 mg/L) and coliform (1540–326,470 CFU/100 mL); moderately polluted by As (0.2–131.15 μg/L) and Hg (0.11–4.1 μg/L); and slightly polluted by NO2− (0.003–0.33 mg/L) and Cd (2.1–18.2 μg/L). The concentrations of NH4+, PO43−, COD, BOD5 and coliform frequently exceeded both drinking water guidelines and irrigation water standards. Regarding PTEs, As, Cd and Hg concentrations were frequently higher than the regulatory limits. Human health risks of PTEs were evaluated by estimating hazard index (HI) and cancer risk through ingestion and dermal contacts for adults and children. The findings indicated that As was the most important pollutant causing both non-carcinogenic and carcinogenic concerns. The non-carcinogenic risks of As were higher than 1.0 at all sites for both adults (HI = 1.83–7.4) and children (HI = 2.6–10.5), while As posed significant carcinogenic risks for adults (1 × 10−4−4.96 × 10−4). A management strategy for controlling wastewater discharge and protecting human health is urgently needed. Graphical abstract: [Figure not available: see fulltext.]
Nguyen, LN, Commault, AS, Johir, MAH, Bustamante, H, Aurisch, R, Lowrie, R & Nghiem, LD 2019, 'Application of a novel molecular technique to characterise the effect of settling on microbial community composition of activated sludge', Journal of Environmental Management, vol. 251, pp. 109594-109594.
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Activated sludge (AS) and return activated sludge (RAS) microbial communities from three full-scale municipal wastewater treatment plants (denoted plant A, B and C) were compared to assess the impact of sludge settling (i.e. gravity thickening in the clarifier) and profile microorganisms responsible for nutrient removal and reactor foaming. The results show that all three plants were dominated with microbes in the phyla of Proteobacteria, Bacteroidetes, Verrucomicrobia, Actinobacteria, Chloroflexi, Firmicutes, Nitrospirae, Spirochaetae, Acidobacteria and Saccharibacteria. AS and RAS shared above 80% similarity in the microbial community composition, indicating that sludge thickening does not significantly alter the microbial composition. Autotrophic and heterotrophic nitrifiers were present in the AS. However, the abundance of autotrophic nitrifiers was significantly lower than that of the heterotrophic nitrifiers. Thus, ammonium removal at these plants was achieved mostly by heterotrophic nitrification. Microbes that can cause foaming were at 3.2% abundance, and this result is well corroborated with occasional aerobic biological reactor foaming. By contrast, these microbes were not abundant (<2.1%) at plant A and C, where aerobic biological reactor foaming has not been reported.
Nguyen, LN, Johir, MAH, Commault, A, Bustamante, H, Aurisch, R, Lowrie, R & Nghiem, LD 2019, 'Impacts of mixing on foaming, methane production, stratification and microbial community in full-scale anaerobic co-digestion process', Bioresource Technology, vol. 281, pp. 226-233.
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© 2019 Elsevier Ltd This study investigated the impact of mixing on key factors including foaming, substrate stratification, methane production and microbial community in three full scale anaerobic digesters. Digester foaming was observed at one plant that co-digested sewage sludge and food waste, and was operated without mixing. The lack of mixing led to uneven distribution of total chemical oxygen demand (tCOD) and volatile solid (VS) as well as methane production within the digester. 16S rRNA gene-based community analysis clearly differentiated the microbial community from the top and bottom. By contrast, foaming and substrate stratification were not observed at the other two plants with internal circulation mixing. The abundance of methanogens (Methanomicrobia) at the top was about four times higher than at the bottom, correlating to much higher methane production from the top verified by ex-situ biomethane assay, causing foaming. This result is consistent with foaming potential assessment of digestate samples from the digester.
Nguyen, LN, Labeeuw, L, Commault, AS, Emmerton, B, Ralph, PJ, Johir, MAH, Guo, W, Ngo, HH & Nghiem, LD 2019, 'Validation of a cationic polyacrylamide flocculant for the harvesting fresh and seawater microalgal biomass', Environmental Technology & Innovation, vol. 16, pp. 100466-100466.
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© 2019 Elsevier B.V. A simple, efficient, and fast settling flocculation technique to harvest microalgal biomass was demonstrated using a proprietary cationic polyacrylamide flocculant for a freshwater (Chlorella vulgaris) and a marine (Phaeodactylum tricornutum) microalgal culture at their mid-stationary growth phase. The optimal flocculant doses were 18.9 and 13.7 mg/g of dry algal biomass for C. vulgaris and P. tricornutum, respectively (equivalent to 7 g per m3 of algal culture for both species). The obtained optimal dose was well corroborated with changes in cell surface charge, and culture solution optical density and turbidity. At the optimal dose, charge neutralization of 64 and 86% was observed for C. vulgaris and P. tricornutum algal cells, respectively. Algae recovery was independent of the culture solution pH in the range of pH 6 to 9. Algal biomass recovery was achieved of 100 and 90% for C vulgaris and P. tricornutum respectively, and over 98% medium recovery was achievable by simple decanting.
Nguyen, LN, Nguyen, AQ, Johir, MAH, Guo, W, Ngo, HH, Chaves, AV & Nghiem, LD 2019, 'Application of rumen and anaerobic sludge microbes for bio harvesting from lignocellulosic biomass', Chemosphere, vol. 228, pp. 702-708.
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This study investigated the production of biogas, volatile fatty acids (VFAs), and other soluble organic from lignocellulosic biomass by two microbial communities (i.e. rumen fluid and anaerobic sludge). Four types of abundant lignocellulosic biomass (i.e. wheat straw, oaten hay, lurence hay and corn silage) found in Australia were used. The results show that rumen microbes produced four-time higher VFAs level than that of anaerobic sludge reactors, indicating the possible application of rumen microorganism for VFAs generation from lignocellulosic biomass. VFA production in the rumen fluid reactors was probably due to the presence of specific hydrolytic and acidogenic bacteria (e.g. Fibrobacter and Prevotella). VFA production corroborated from the observation of pH drop in the rumen fluid reactors indicated hydrolytic and acidogenic inhibition, suggesting the continuous extraction of VFAs from the reactor. Anaerobic sludge reactors on the other hand, produced more biogas than that of rumen fluid reactors. This observation was consistent with the abundance of methanogens in anaerobic sludge inoculum (3.98% of total microbes) compared to rumen fluid (0.11%). VFA production from lignocellulosic biomass is the building block chemical for bioplastic, biohydrogen and biofuel. The results from this study provide important foundation for the development of engineered systems to generate VFAs from lignocellulosic biomass.
Nguyen, QD, Khan, MSH, Castel, A & Kim, T 2019, 'Durability and Microstructure Properties of Low-Carbon Concrete Incorporating Ferronickel Slag Sand and Fly Ash', Journal of Materials in Civil Engineering, vol. 31, no. 8, pp. 04019152-04019152.
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© 2019 American Society of Civil Engineers. Ferronickel slag (FNS) which is also known as electric arc furnace slag is a byproduct of the production of ferronickel alloy. The production of FNS at Société Le Nickel (SLN) in New Caledonia is about 2 Mt per year with an existing stockpile of 25 Mt, which presents an excellent potential for concrete applications in the Pacific region. The possibility of using FNS from SLN as fine aggregate replacement in concrete is investigated. The low-carbon-concrete mix design includes 50% natural sand replacement by FNS sand and 25% ordinary portland cement substitution by fly ash. Microstructural analysis by scanning electron microscopy - energy dispersive X-ray spectrometer (SEM-EDS) of the interface transition zone (ITZ) of FNS sand shows that the excess in Portlandite weakening the ITZ of natural aggregate is absent in FNS sand ITZ. As a result, the resistance against chemically aggressive ions diffusion, water absorption, sorptivity, bulk and surface resistivity, and volume of permeable voids are significantly improved compared with the reference concretes due to the pozzolanic effect of FNS strengthening the ITZ. The substitution of 50% natural sand by FNS sand allows offsetting the detrimental effect of using fly ash on the concrete resistance against carbonation. All results show that using FNS sand in concrete can improve the concrete performance.
Nguyen, QD, Khan, MSH, Xu, T & Castel, A 2019, 'Mitigating the Risk of Early Age Cracking in Fly Ash Blended Cement-Based Concrete Using Ferronickel Slag Sand', Journal of Advanced Concrete Technology, vol. 17, no. 6, pp. 295-308.
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Copyright © 2019 Japan Concrete Institute. A concrete mix (FNS25) including 50% natural sand replacement by ferronickel slag (FNS) sand and 25% ordinary portland cement (OPC) substitution by fly ash (FA) was considered to mitigate the risk of early-age cracking in fly ash blended cement-based concrete. Experiments were carried out to accurately quantify early-age shrinkage and tensile creep and assess their influence on early-age cracking in reinforced concrete members. The results show the free shrinkage strain is not influenced by either fly ash or FNS significantly, whereas the tensile creep of FNS25 is significantly larger than that of both OPC100 and FA20. Both restrained ring test and simulations on reinforced concrete members confirm that partly replacing conventional sand by FNS sand reduces the risk of early-age cracking. Microstructural analysis of the Interface Transition Zone (ITZ) of FNS sand shows that excess in Portlandite is absent in FNS sand ITZ leading to a higher early-age tensile strength of FNS25 concrete.
Nguyen, TKL, Ngo, HH, Guo, W, Chang, SW, Nguyen, DD, Nghiem, LD, Liu, Y, Ni, B & Hai, FI 2019, 'Insight into greenhouse gases emissions from the two popular treatment technologies in municipal wastewater treatment processes', Science of The Total Environment, vol. 671, pp. 1302-1313.
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© 2019 Elsevier B.V. Due to the impact of methane, carbon dioxide and nitrous oxide on global warming, the quantity of these greenhouse gases (GHG) emissions from municipal wastewater treatment plants (WWTPs) has attracted more and more attention. Consequently, GHG emissions from the two popular treatment technologies: anaerobic/anoxic/oxic (AAO) process and sequencing batch reactor (SBR) should be properly identified and discussed toward the current situation in developing countries. Direct and indirect carbon dioxide (with and/or without including in Intergovernmental Panel on Climate Change (IPCC) report) are all discussed in this article. This literature study observed that a quantity of total carbon dioxide emissions from SBR (374 g/m3 of wastewater) was double that of AAO whilst 10% of these was direct carbon dioxide. Methane emitted from an SBR was 0.50 g/m3 wastewater while 0.18 g CH4/m3 wastewater was released from an AAO. The level of nitrous oxide from AAO and SBR accounted for 0.97 g/m3 wastewater and 4.20 g/m3 wastewater, respectively. Although these results were collected from different WWTPs and where influent was in various states, GHGs emitted from both biological units and other treatment units in various processes are significant. The results also revealed that aerated zone is the major contributing factor in a wastewater treatment plant to the large amount of GHG emissions.
Nguyen, TN, Yu, Y, Li, J, Gowripalan, N & Sirivivatnanon, V 2019, 'Elastic modulus of ASR-affected concrete: An evaluation using Artificial Neural Network', Computers and Concrete, vol. 24, no. 6, pp. 541-553.
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Alkali-silica reaction (ASR) in concrete can induce degradation in its mechanical properties, leading to compromised serviceability and even loss in load capacity of concrete structures. Compared to other properties, ASR often affects the modulus of elasticity more significantly. Several empirical models have thus been established to estimate elastic modulus reduction based on the ASR expansion only for condition assessment and capacity evaluation of the distressed structures. However, it has been observed from experimental studies in the literature that for any given level of ASR expansion, there are significant variations on the measured modulus of elasticity. In fact, many other factors, such as cement content, reactive aggregate type, exposure condition, additional alkali and concrete strength, have been commonly known in contribution to changes of concrete elastic modulus due to ASR. In this study, an artificial intelligent model using artificial neural network (ANN) is proposed for the first time to provide an innovative approach for evaluation of the elastic modulus of ASR-affected concrete, which is able to take into account contribution of several influence factors. By intelligently fusing multiple information, the proposed ANN model can provide an accurate estimation of the modulus of elasticity, which shows a significant improvement from empirical based models used in current practice. The results also indicate that expansion due to ASR is not the only factor contributing to the stiffness change, and various factors have to be included during the evaluation.
Nguyen, TT & Indraratna, B 2019, 'Micro-CT Scanning to Examine Soil Clogging Behavior of Natural Fiber Drains', Journal of Geotechnical and Geoenvironmental Engineering, vol. 145, no. 9, pp. 04019037-04019037.
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© 2019 American Society of Civil Engineers. The use of jute and coir fibers as natural fiber drains to facilitate drainage and soft soil stabilization has been proposed for decades. However, their uncertain hydraulic behavior has often hampered their wider application in major infrastructure projects. Because these drains have a complex porous structure that can trap soil particles and reduce their discharge capacity, a comprehensive laboratory investigation in which soft soil was used to interact with different fiber drains under varying confining pressure was conducted via a discharge capacity test scheme. Nondestructive micro-computed tomography (CT) scanning followed by a series of image processing techniques was applied to the drains to capture their three-dimensional porous characteristics, which were then used to clarify their hydraulic behavior. The study revealed that there are two major types of components - intra- and interbundle voids - making porosity in a fiber drain, and they can be used to evaluate the drain discharge capacity. The larger the interbundle porosity, the higher the drain discharge capacity. Jute filters not only enlarge the interbundle porosity but also - if they are thick enough - help drains resist undue lateral pressure and clogging. Fiber drains are more sensitive to confinement than polymeric drains, because their discharge capacity decreases considerably at higher confining pressures. This study enables the hydraulic properties of natural fiber drains subjected to soil clogging to be properly understood so that drain designs can be optimized to make them more competitive with conventional polymeric drains.
Nguyen, T-T, Bui, X-T, Dang, B-T, Ngo, H-H, Jahng, D, Fujioka, T, Chen, S-S, Dinh, Q-T, Nguyen, C-N & Nguyen, P-T-V 2019, 'Effect of ciprofloxacin dosages on the performance of sponge membrane bioreactor treating hospital wastewater', Bioresource Technology, vol. 273, pp. 573-580.
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© 2018 Elsevier Ltd This study aimed to evaluate treatment performance and membrane fouling of a lab-scale Sponge-MBR under the added ciprofloxacin (CIP) dosages (20; 50; 100 and 200 µg L−1) treating hospital wastewater. The results showed that Sponge-MBR exhibited effective removal of COD (94–98%) during the operation period despite increment of CIP concentrations from 20 to 200 µg L−1. The applied CIP dosage of 200 µg L−1 caused an inhibition of microorganisms in sponges, i.e. significant reduction of the attached biomass and a decrease in the size of suspended flocs. Moreover, this led to deteriorating the denitrification rate to 3–12% compared to 35% at the other lower CIP dosages. Importantly, Sponge-MBR reinforced the stability of CIP removal at various added CIP dosages (permeate of below 13 µg L−1). Additionally, the fouling rate at CIP dosage of 200 µg L−1 was 30.6 times lower compared to the control condition (no added CIP dosage).
Nguyen, TT, Indraratna, B, Kelly, R, Phan, NM & Haryono, F 2019, 'Mud pumping under railtracks: Mechanisms, assessments and solutions', Australian Geomechanics Journal, vol. 54, no. 4, pp. 59-80.
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Mud pumping under railway tracks has received increasing attention from academic and practical perspectives in recent decades, however, the actual mechanisms and possible solutions are still not understood or well established. Frequent investigations in countries such as Japan, Canada, the USA, China, Australia, the UK, and other European regions where railway systems are the largest and most advanced, indicate that mud pumping still leads to high annual maintenance costs. On this basis, a thorough review is therefore essential, so this paper presents a systematic and comprehensive review of mud pumping in railways. In particular three primary aspects of mud pumping are addressed: (i) the phenomena and mechanisms; (ii) assessments; and (iii) solutions. The review shows the three essential factors that trigger mud pumping, i.e., excess fines, excess water, and cyclic loads. While excess fines can be induced by subgrade fluidisation, ballast breakdown and external sources, the excess water is mainly due to insufficient drainage in the foundations. Given these 3 factors, different contexts where mud pumping can be instigated are summarised such as subgrade fluidisation and infiltration, peat boils from soft roadbeds and upward migration of non-subgrade fines. Unfavourable weather condition, poor sleeper-ballast contact and stress/strain concentration at particular sections such as rail joints, switches, crossings and transition zones can accelerate the inception of mud pumping. In all cases, the generation of excess pore pressure is the driving mechanism. The study also summarises the laboratory and in-situ techniques currently used to assess mud pumping. 4 major groups of mud pumping solutions are highlighted with their advantages and disadvantages: (1) clean, modify and renew problematic layers; (2) enhance drainage condition; (3) geosynthetics; and (4) chemical stabilisations.
Nguyen, TT, Ngo, HH, Guo, W, Wang, XC, Ren, N, Li, G, Ding, J & Liang, H 2019, 'Implementation of a specific urban water management - Sponge City', Science of The Total Environment, vol. 652, pp. 147-162.
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© 2018 Elsevier B.V. Climate change, rapid urbanization and inappropriate urban planning policies in many countries have resulted in urban water-related problems, such as flooding disasters, water pollution and water shortages. To tackle these issues, the specific urban water management strategy known as Sponge City has been implemented in China since 2013. This is a complex method and one involving many challenges. This paper critically assesses the approaches associated with conventional urban water management. The Sponge City concept and its adoption are then scrutinized to comprehensively assess the limitations and opportunities. It emerges that Sponge City has four main principles, these being: urban water resourcing, ecological water management, green infrastructures, and urban permeable pavement. The uncertainties in Sponge City design and planning, and financial insufficiencies are the most serious problems that can risk the failure of the Sponge City concept. While significant barriers exist, the opportunities for implementing a Sponge City are evident. To obtain multi-ecosystem services of Sponge City, it should be implemented at the watershed scales and be flexible, depending on different decision levels or catchment characteristics. It is essential to apply an intelligent decision-making mechanism and consider the need for close cooperation between various agencies with which the central government can work. A suitable sized and harmonious Sponge City, ensuring a good balance between socio-economic development and environmental conservation, is the ideal.
Nguyen, XC, Chang, SW, Tran, TCP, Nguyen, TTN, Hoang, TQ, Banu, JR, Al-Muhtaseb, AH, La, DD, Guo, W, Ngo, HH & Nguyen, DD 2019, 'Comparative study about the performance of three types of modified natural treatment systems for rice noodle wastewater', Bioresource Technology, vol. 282, pp. 163-170.
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© 2019 Elsevier Ltd In this study, three semi-pilot scale systems (vertical flow constructed wetland, multi-soil layering, and integrated hybrid systems) for treating real rice noodle wastewater were operated parallelly for the first time in a tropical climate at a loading rate of 50 L/(m2·d) for more than 7 months to determine the optimal conditions and to compare their treatment performance. The results demonstrated that these systems were appropriate for the removal of organics, suspended solids, and total coliform (Tcol). The highest reductions in chemical oxygen demand (CODCr, 73.2%), phosphorus (PO4-P, 54%), and Tcol (4.78 log MPN/100 mL inactivation) were obtained by the integrated hybrid system, while the highest removal efficiencies of ammonium (NH4-N, 60.64%) and suspended solids (80.49%) were achieved in the vertical-flow-constructed wetland and multi-soil layering systems respectively.
Ni, B-J, Huang, Q-S, Wang, C, Ni, T-Y, Sun, J & Wei, W 2019, 'Competitive adsorption of heavy metals in aqueous solution onto biochar derived from anaerobically digested sludge', Chemosphere, vol. 219, pp. 351-357.
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© 2018 Elsevier Ltd Heavy metals often coexist in contaminated wastewater systems and their competitive behavior could affect the adsorption capacity of biochar. Till now, the competitive adsorption of heavy metals by biochar derived from anaerobically digested sludge has never been reported. In this work, biochar from anaerobically digested sludge was synthesized and characterized to explore the competitive behavior of widely co-existed Pb(II) and Cd(II). The mutual effects and inner mechanisms of their adsorption on studied biochar were systematically investigated via single-metal and binary-metals systems. In single-metal system, the biochar exhibited much higher adsorption capacity for Pb(II) compared to that for Cd(II). The maximum adsorption capacities of Pb(II) and Cd(II) based on single-component adsorption isotherm were 0.75 and 0.55 mmoL/g, respectively, which were much higher than those reported biochars from different materials. In binary-metals system, the Cd(II) adsorption on biochar was severely inhibited, while the uptake of Pb(II) was not affected significantly. The results of binary-components adsorption isotherm clearly demonstrated the competitive adsorption between two metals occurred as well as the preference of biochar for Pb(II) compared to Cd(II). FTIR and metal characteristics analysis results revealed that Pb(II) had exactly the same adsorption sites with Cd(II), but Pb(II) has a greater affinity than Cd(II), thereby exhibiting a competitive advantage in the coexisting system.
Ni, B-J, Yan, X, Sun, J, Chen, X, Peng, L, Wei, W, Wang, D, Mao, S, Dai, X & Wang, Q 2019, 'Persulfate and zero valent iron combined conditioning as a sustainable technique for enhancing dewaterability of aerobically digested sludge', Chemosphere, vol. 232, pp. 45-53.
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© 2019 Elsevier Ltd Aerobic digestion followed by dewatering is a widely applied method for sludge stabilization and reduction in decentralized wastewater treatment plants. It is important to enhance the sludge dewaterability of the aerobically digested sludge due to its considerable impact on cost of sludge disposal and management. In this study, an innovative technique is developed for improving the dewaterability of aerobically digested sludge by combined conditioning with persulfate (PS) and zero valent iron (ZVI). The results demonstrated that the dewaterability of aerobically digested sludge could be significantly enhanced with the PS and ZVI dosage in the range of 0–0.5 g/gTS and 0–0.4 g/gTS, respectively. The highest improvement was achieved at 0.05 g ZVI/g TS with 0.1 g PS/g TS, and the capillary suction time was reduced by ∼80%. The extracellular polymeric substances (EPS) characterization revealed that the combined PS-ZVI treatment could largely reduce proteins, polysaccharides and humic acids-like compounds in the tightly bounded EPS of the aerobically digested sludge, leading to bound water releasing from sludge flocs. The recovery of the ZVI particles could reach around 45%–80% after the treatment, further proved the sustainability of the approach. The proposed PS-ZVI conditioning would not have significant impact on the final choice of sludge disposal and the mainstream wastewater treatment. However, plant-scale test are still required for better assessing the proposed technique.
Nie, W-B, Xie, G-J, Ding, J, Lu, Y, Liu, B-F, Xing, D-F, Wang, Q, Han, H-J, Yuan, Z & Ren, N-Q 2019, 'High performance nitrogen removal through integrating denitrifying anaerobic methane oxidation and Anammox: from enrichment to application', Environment International, vol. 132, pp. 105107-105107.
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© 2019 The Authors Integrating denitrifying anaerobic methane oxidation (DAMO) with Anammox provides alternative solutions to simultaneously remove nitrogen and mitigate methane emission from wastewater treatment. However, the practical application of DAMO has been greatly limited by slow-growing DAMO microorganisms living on low-solubility gaseous methane. In this work, DAMO and Anammox co-cultures were fast enriched using high concentration of mixed sludges from various environments, and achieved nitrogen removal rate of 76.7 mg NH4+-N L−1 d−1 and 87.9 mg NO3−-N L−1 d−1 on Day 178. Subsequently, nitrogen removal rate significantly decreased but recovered quickly through increasing methane flushing frequency, indicating methane availability could be the limiting factor of DAMO activity. Thus, this work developed a novel Membrane Aerated Membrane Bioreactor (MAMBR), which equipped with gas permeable membrane for efficient methane delivery and ultrafiltration membrane for complete biomass retention. After inoculated with enriched sludge, nitrogen removal rates of MAMBR were significantly enhanced to 126.9 mg NH4+-N L−1 d−1 and 158.8 mg NO3−-N L−1 d−1 by membrane aeration in batch test. Finally, the MAMBR was continuously fed with synthetic wastewater containing ammonium and nitrite to mimic the effluent from partial nitritation. When steady state with nitrogen loading rate of 2500 mg N L−1 d−1 was reached, the MAMBR achieved total nitrogen removal of 2496.7 mg N L−1 d−1, with negligible nitrate in effluent (~6.5 mg NO3−-N L−1). 16S rRNA amplicon sequencing and fluorescence in situ hybridization revealed the microbial community dynamics during enrichment and application. The high performance of nitrogen removal (2.5 kg N m−3 d−1) within 200 days operation and excellent biomass retention capacity (8.67 kg VSS m−3) makes the MAMBR promising for practical application of DAMO and Anammox in wastewater treatment.
Nimbalkar, Pain, Ahmad & Chen 2019, 'Stability Assessment of Earth Retaining Structures under Static and Seismic Conditions', Infrastructures, vol. 4, no. 2, pp. 15-15.
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An accurate estimation of static and seismic earth pressures is extremely important in geotechnical design. The conventional Coulomb’s approach and Mononobe-Okabe’s approach have been widely used in engineering practice. However, the latter approach provides the linear distribution of seismic earth pressure behind a retaining wall in an approximate way. Therefore, the pseudo-dynamic method can be used to compute the distribution of seismic active earth pressure in a more realistic manner. The effect of wall and soil inertia must be considered for the design of a retaining wall under seismic conditions. The method proposed considers the propagation of shear and primary waves through the backfill soil and the retaining wall due to seismic excitation. The crude estimate of finding the approximate seismic acceleration makes the pseudo-static approach often unreliable to adopt in the stability assessment of retaining walls. The predictions of the active earth pressure using Coulomb theory are not consistent with the laboratory results to the development of arching in the backfill soil. A new method is proposed to compute the active earth pressure acting on the backface of a rigid retaining wall undergoing horizontal translation. The predictions of the proposed method are verified against results of laboratory tests as well as the results from other methods proposed in the past.
Nimbalkar, SS, Punetha, P, Basack, S & Mirzababaei, M 2019, 'Piles Subjected to Torsional Cyclic Load: Numerical Analysis', Frontiers in Built Environment, vol. 5.
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Pile foundations supporting large structures (such as high-rise buildings, oil drilling platforms, bridges etc). are often subjected to eccentric lateral load (in addition to the vertical loads) due to the action of wind, waves, high speed traffic, and ship impacts etc. The eccentric lateral load, which is usually cyclic (repetitive) in nature, induces torsion in the pile foundation. This paper presents a numerical model based on boundary element approach to study the performance of a single pile subjected to the torsional cyclic load. The model is initially validated by comparing it with the experimental data available from the literature. Thereafter, the model has been utilized to conduct a parametric study to understand the influence of the torsional cyclic loading parameters on the axial pile capacity. The results indicated that the model is able to capture the degradation in the axial pile capacity due to the torsional cyclic loading with a reasonable accuracy. Moreover, the parametric study showed that the frequency, amplitude and number of cycles play a significant role in the torsional cyclic response of the pile. The present study is essential for the development of design guidelines for pile foundations subjected to torsional cyclic load.
Niu, Q, Xu, Q, Wang, Y, Wang, D, Liu, X, Liu, Y, Wang, Q, Ni, B-J, Yang, Q, Li, X & Li, H 2019, 'Enhanced hydrogen accumulation from waste activated sludge by combining ultrasonic and free nitrous acid pretreatment: Performance, mechanism, and implication', Bioresource Technology, vol. 285, pp. 121363-121363.
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© 2019 Elsevier Ltd This study presents a novel and effective method, i.e., adding nitrite into acidic fermentations after ultrasonic (US) pretreatment to form free nitrous acid (FNA), to further enhance hydrogen yield. Experimental results showed that when 180 mg/L nitrite was added into the US (2 W/mL, 15 min) pretreated waste activated sludge (WAS), the maximal hydrogen yield of 24.81 ± 1.24 mL/g VSS (volatile suspended solids) was obtained under acidic fermentation (1.0 mg/L FNA was initially formed under this condition), which was 2.21-folds (or 1.36-folds) of that from US pretreatment (or FNA treatment) alone. This combination approach caused a positive synergy on sludge disintegration and enhanced the transformation of the released organics from non-biodegradable to biodegradable. Further study showed that the inhibiting effect of this combination method on hydrogen consuming microorganism was severer. Considering its pollution free, this combination strategy is an attractive technology for hydrogen recovery from WAS.
Nohani, Moharrami, Sharafi, Khosravi, Pradhan, Pham, Lee & Melesse 2019, 'Landslide Susceptibility Mapping Using Different GIS-Based Bivariate Models', Water, vol. 11, no. 7, pp. 1402-1402.
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Landslides are the most frequent phenomenon in the northern part of Iran, which cause considerable financial and life damages every year. One of the most widely used approaches to reduce these damages is preparing a landslide susceptibility map (LSM) using suitable methods and selecting the proper conditioning factors. The current study is aimed at comparing four bivariate models, namely the frequency ratio (FR), Shannon entropy (SE), weights of evidence (WoE), and evidential belief function (EBF), for a LSM of Klijanrestagh Watershed, Iran. Firstly, 109 locations of landslides were obtained from field surveys and interpretation of aerial photographs. Then, the locations were categorized into two groups of 70% (74 locations) and 30% (35 locations), randomly, for modeling and validation processes, respectively. Then, 10 conditioning factors of slope aspect, curvature, elevation, distance from fault, lithology, normalized difference vegetation index (NDVI), distance from the river, distance from the road, the slope angle, and land use were determined to construct the spatial database. From the results of multicollinearity, it was concluded that no collinearity existed between the 10 considered conditioning factors in the occurrence of landslides. The receiver operating characteristic (ROC) curve and the area under the curve (AUC) were used for validation of the four achieved LSMs. The AUC results introduced the success rates of 0.8, 0.86, 0.84, and 0.85 for EBF, WoE, SE, and FR, respectively. Also, they indicated that the rates of prediction were 0.84, 0.83, 0.82, and 0.79 for WoE, FR, SE, and EBF, respectively. Therefore, the WoE model, having the highest AUC, was the most accurate method among the four implemented methods in identifying the regions at risk of future landslides in the study area. The outcomes of this research are useful and essential for the government, planners, decision makers, researchers, and general land-use planners in the ...
Noori, AM, Pradhan, B & Ajaj, QM 2019, 'Dam site suitability assessment at the Greater Zab River in northern Iraq using remote sensing data and GIS', Journal of Hydrology, vol. 574, pp. 964-979.
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Noori, L, Pour, A, Askari, G, Taghipour, N, Pradhan, B, Lee, C-W & Honarmand, M 2019, 'Comparison of Different Algorithms to Map Hydrothermal Alteration Zones Using ASTER Remote Sensing Data for Polymetallic Vein-Type Ore Exploration: Toroud–Chahshirin Magmatic Belt (TCMB), North Iran', Remote Sensing, vol. 11, no. 5, pp. 495-495.
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Polymetallic vein-type ores are important sources of precious metal and a principal type of orebody for various base-metals. In this research, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing data were used for mapping hydrothermal alteration zones associated with epithermal polymetallic vein-type mineralization in the Toroud–Chahshirin Magmatic Belt (TCMB), North of Iran. The TCMB is the largest known goldfield and base metals province in the central-north of Iran. Propylitic, phyllic, argillic, and advanced argillic alteration and silicification zones are typically associated with Au-Cu, Ag, and/or Pb-Zn mineralization in the TCMB. Specialized image processing techniques, namely Selective Principal Component Analysis (SPCA), Band Ratio Matrix Transformation (BRMT), Spectral Angle Mapper (SAM) and Mixture Tuned Matched Filtering (MTMF) were implemented and compared to map hydrothermal alteration minerals at the pixel and sub-pixel levels. Subtle differences between altered and non-altered rocks and hydrothermal alteration mineral assemblages were detected and mapped in the study area. The SPCA and BRMT spectral transformation algorithms discriminated the propylitic, phyllic, argillic and advanced argillic alteration and silicification zones as well as lithological units. The SAM and MTMF spectral mapping algorithms detected spectrally dominated mineral groups such as muscovite/montmorillonite/illite, hematite/jarosite, and chlorite/epidote/calcite mineral assemblages, systematically. Comprehensive fieldwork and laboratory analysis, including X-ray diffraction (XRD), petrographic study, and spectroscopy were conducted in the study area for verifying the remote sensing outputs. Results indicate several high potential zones of epithermal polymetallic vein-type mineralization in the northeastern and southwestern parts of the study area, which can be considered for future systematic exploration programs. The appr...
Noushini, A, Castel, A & Gilbert, RI 2019, 'Creep and shrinkage of synthetic fibre-reinforced geopolymer concrete', Magazine of Concrete Research, vol. 71, no. 20, pp. 1070-1082.
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This paper presents the results of an investigation on the use of synthetic polypropylene (PP) and polyolefin (PO) fibres to improve the creep and shrinkage performance of low-calcium fly ash-based geopolymer concrete. Three PP fibres of 18, 19 and 51 mm length and two PO fibres of 48 and 55 mm length with a volume fraction of 0·5% were added to geopolymer concrete. The mechanical properties of the resulting material, such as compressive and splitting tensile strength, modulus of elasticity and modulus of rupture, have been studied. The drying shrinkage and creep of plain and fibre-reinforced geopolymer concrete were examined for a period of 1 year. The results revealed that the inclusion of PP and PO fibres in a volume fraction of 0·5% decreased the drying shrinkage and increased the compressive creep of fly ash-based geopolymer concrete at both early ages and in the long term.
Nur, T, Loganathan, P, Ahmed, MB, Johir, MAH, Nguyen, TV & Vigneswaran, S 2019, 'Removing arsenic from water by coprecipitation with iron: Effect of arsenic and iron concentrations and adsorbent incorporation', Chemosphere, vol. 226, pp. 431-438.
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© 2019 Elsevier Ltd Arsenic (As) contamination of drinking water is a major cause of As toxicity in many parts of the world. A study was conducted to evaluate As removal from water containing 100–700 μg/L of As and As to Fe concentration ratios of 1:5–1:1000 using the coprecipitation process with and without As/Fe adsorption onto granular activated carbon (GAC). Fe concentration required to reduce As concentrations in order to achieve the WHO standard level of 10 μg/L increased exponentially with the increase in initial As concentration. When small amounts of GAC were added to the As/Fe solutions the Fe required to remove these As concentrations reduced drastically. This decline was due to the GAC adsorption of Fe and As, enhancing the removal of these metals through coprecipitation. Predictive regression equations were developed relating the GAC dose requirement to the initial As and Fe concentrations. Zeta potential data revealed that As was adsorbed on the GAC by outer-sphere complexation whereas Fe was adsorbed by inner-sphere complexation reversing the negative charge on GAC to positive values. X-ray diffraction of the GAC samples in the presence of Fe had an additional peak characteristic of ferrihydrite (Fe oxide) compared to that of the GAC sample without Fe. The study showed that incorporating an adsorbent into the coprecipitation process has the advantage of removing As from waters at all concentrations of Fe and As compared to coprecipitation alone which does not remove As to the required levels if Fe concentration is low.
Ogie, RI & Pradhan, B 2019, 'Natural Hazards and Social Vulnerability of Place: The Strength-Based Approach Applied to Wollongong, Australia', International Journal of Disaster Risk Science, vol. 10, no. 3, pp. 404-420.
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© 2019, The Author(s). Natural hazards pose significant threats to different communities and various places around the world. Failing to identify and support the most vulnerable communities is a recipe for disaster. Many studies have proposed social vulnerability indices for measuring both the sensitivity of a population to natural hazards and its ability to respond and recover from them. Existing techniques, however, have not accounted for the unique strengths that exist within different communities to help minimize disaster loss. This study proposes a more balanced approach referred to as the strength-based social vulnerability index (SSVI). The proposed SSVI technique, which is built on sound sociopsychological theories of how people act during disasters and emergencies, is applied to assess comparatively the social vulnerability of different suburbs in the Wollongong area of New South Wales, Australia. The results highlight suburbs that are highly vulnerable, and demonstrates the usefulness of the technique in improving understanding of hotspots where limited resources should be judiciously allocated to help communities improve preparedness, response, and recovery from natural hazards.
Ong, HC, Chen, W-H, Farooq, A, Gan, YY, Lee, KT & Ashokkumar, V 2019, 'Catalytic thermochemical conversion of biomass for biofuel production: A comprehensive review', Renewable and Sustainable Energy Reviews, vol. 113, pp. 109266-109266.
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© 2019 Elsevier Ltd The increasing demand for energy and diminishing sources of fossil fuels have called for the discovery of new energy sources. The effective energy conversion process of biomass is able to fulfill energy needs. Among the advanced biomass conversion technologies, thermochemical processes hold considerable potential approaches and needed for optimization. Thus, this study presents a comprehensive review of the research and development on the effects of catalysts on the thermochemical conversion of biomass to determine the progress of catalytic thermochemical conversion processes. The effects of catalysts on torrefaction, pyrolysis, hydrothermal liquefaction, and gasification are highlighted. Aspects related to reaction conditions, reactor types, and products are discussed comprehensively with the reaction mechanisms involved in the catalytic effects. Hydrogenation and hydrodeoxygenation can occur in the presence of zeolite catalysts during fast pyrolysis while producing highly aromatic bio-oil. A heterogeneous catalyst in liquefaction increases the hydrocarbon content and decreases viscosity, acid value, and oxygenated compounds in the bio-oil. Thus, expanding and enhancing knowledge about catalyst utilization in the thermochemical conversion technologies of biomass will play an important role in the generation of renewable and carbon-neutral fuels.
Ong, HC, Milano, J, Silitonga, AS, Hassan, MH, Shamsuddin, AH, Wang, C-T, Indra Mahlia, TM, Siswantoro, J, Kusumo, F & Sutrisno, J 2019, 'Biodiesel production from Calophyllum inophyllum-Ceiba pentandra oil mixture: Optimization and characterization', Journal of Cleaner Production, vol. 219, pp. 183-198.
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© 2019 Elsevier Ltd In this study, a novel modeling approach (artificial neural networks (ANN) and ant colony optimization (ACO)) was used to optimize the process variables for alkaline-catalyzed transesterification of CI40CP60 oil mixture (40 wt% of Calophyllum inophyllum oil mixed with 60 wt% of Ceiba pentandra oil) in order to maximize the biodiesel yield. The optimum values of the methanol-to-oil molar ratio, potassium hydroxide catalyst concentration, and reaction time predicted by the ANN-ACO model are 37%, 0.78 wt%, and 153 min, respectively, at a constant reaction temperature and stirring speed of 60 °C and 1000 rpm, respectively. The ANN-ACO model was validated by performing independent experiments to produce the CI40CP60 methyl ester (CICPME) using the optimum transesterification process variables predicted by the ANN-ACO model. There is very good agreement between the average CICPME yield determined from experiments (95.18%) and the maximum CICPME yield predicted by the ANN-ACO model (95.87%) for the same optimum values of process variables, which corresponds to a difference of 0.69%. Even though the ANN-ACO model is only implemented to optimize the transesterification of process variables in this study. It is believed that the model can be used to optimize other biodiesel production processes such as seed oil extraction and acid-catalyzed esterification for various types of biodiesels and biodiesel blends.
Ooi, XY, Gao, W, Ong, HC, Lee, HV, Juan, JC, Chen, WH & Lee, KT 2019, 'Overview on catalytic deoxygenation for biofuel synthesis using metal oxide supported catalysts', Renewable and Sustainable Energy Reviews, vol. 112, pp. 834-852.
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Ooi, XY, Oi, LE, Choo, M-Y, Ong, HC, Lee, HV, Show, PL, Lin, Y-C & Juan, JC 2019, 'Efficient deoxygenation of triglycerides to hydrocarbon-biofuel over mesoporous Al2O3-TiO2 catalyst', Fuel Processing Technology, vol. 194, pp. 106120-106120.
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© 2019 Elsevier B.V. The renewable hydrocarbon-like biofuel from biomass is crucial to substitute fossil fuel. A series of mesoporous Al2O3-TiO2 mixed oxide catalysts with different TiO2 content (0.1Ti-0.9Al, 0.2Ti-0.8Al and 0.3Ti-0.7Al) have been synthesized. The physicochemical properties of the catalysts were characterized by XRD, FESEM-EDX, BET, FTIR, NH3-TPD, FTIR-Py, and TGA. The deoxygenation (DO) of triglyceride (i.e. triolein) was carried out in the absence of hydrogen and solvent. The mesoporous Al2O3-TiO2 catalysts showed high catalytic activity performance as compared to that of Al2O3 and TiO2. It was found that 0.2Ti-0.8Al catalyst exhibited the highest conversion (76.86%), and selectivity (27.26%) toward n-C15 + n-C17 at 380 °C after 4 h. The excellence performance of mesoporous Al2O3-TiO2 was attributed to its acidity, mesoporosity and larger surface area. The results reveal that the mesoporous Al2O3-TiO2 catalyst is a promising catalyst for the synthesis of hydrocarbon-like biofuel.
Organ, B, Huang, Y, Zhou, JL, Surawski, NC, Yam, Y-S, Mok, W-C & Hong, G 2019, 'A remote sensing emissions monitoring programme reduces emissions of gasoline and LPG vehicles', Environmental Research, vol. 177, pp. 108614-108614.
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© 2019 Elsevier Inc. Vehicle emissions are a major source of air pollution in Hong Kong affecting human health. A ‘strengthened emissions control of gasoline and liquefied petroleum gas (LPG) vehicles’ programme has been operating in Hong Kong since September 2014 utilising remote sensing (RS) technology. RS has provided measurement data to successfully identify high emitting gasoline and LPG vehicles which then need to be repaired or removed from the on-road vehicle fleet. This paper aims to evaluate the effectiveness of this globally unique RS monitoring programme. A large RS dataset of 2,144,422 records was obtained covering the period from 6th January 2012 to 30th December 2016, of which 1,206,762 records were valid and suitable for further investigation. The results show that there have been significant reductions of emissions factors (EF) for 40.5% HC, 45.3% CO and 29.6% NO for gasoline vehicles. Additionally, EF reductions of 48.4% HC, 41.1% CO and 58.7% NO were achieved for LPG vehicles. For the combined vehicle fleet, the reductions for HC, CO and NO were 55.9%, 50.5% and 60.9% respectively during this survey period. The findings demonstrate that the strengthened emissions control programme utilising RS has been very effective in identifying high emitting vehicles for repair so as to reduce the emissions from gasoline and LPG vehicles under real driving.
Pallewattha, M, Indraratna, B, Heitor, A & Rujikiatkamjorn, C 2019, 'Shear strength of a vegetated soil incorporating both root reinforcement and suction', Transportation Geotechnics, vol. 18, pp. 72-82.
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© 2018 Shear strength of the root permeated soil increases due to the mechanical effects of root reinforcement and most of the past studies have been conducted to capture this effect under saturated soil conditions. However, the soil adjacent to the tree roots is usually in an unsaturated condition and this leads to alterations in root-soil interaction mechanisms and associated shear strength of the root permeated soil system. In this paper, the increment in shear strength is studied considering both the effect of suction and root reinforcement patterns. A number of direct shear tests were conducted for different suction levels in root-permeated and unreinforced soil specimens. The results indicate that the shear strength behaviour of the soil-root system is governed by the level of suction and root failure patterns and a new mathematical model incorporating the effect of both parameters is proposed.
Pan, Y, Liu, Y, Peng, L, Ngo, HH, Guo, W, Wei, W, Wang, D & Ni, B-J 2019, 'Substrate Diffusion within Biofilms Significantly Influencing the Electron Competition during Denitrification', Environmental Science & Technology, vol. 53, no. 1, pp. 261-269.
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© 2018 American Chemical Society. A common and long-existing operational issue of wastewater denitrification is the unexpected accumulation of nitrite (NO 2- ) that could suppress the activity of various microorganisms involved in biological wastewater treatment process and nitrous oxide (N 2 O) that could emit as a potent greenhouse gas. Recently, it has been confirmed that the accumulation of these denitrification intermediates in biological wastewater treatment process is greatly influenced by the electron competition between the four denitrification steps. However, little is known about this in biofilm systems. In this work, we applied a mathematical model that links carbon oxidation and nitrogen reduction processes through a pool of electron carriers, to assess electron competition in denitrifying biofilms. Simulations were performed comprehensively at seven combinations of electron acceptor addition scheme (i.e., simultaneous addition of one, two or three among nitrate (NO 3- ), NO 2- , and N 2 O) to compare the effect of electron competition on NO 3- , NO 2- and N 2 O reduction. Overall, the effects of substrate loading, biofilm thickness and effective diffusion coefficients on electron competition are not always intuitive. Model simulations show that electron competition was intensified due to the substrate load limitation (from 120 to 20 mg COD/L) and increasing biofilm thicknesses (from 0.1 to 1.6 mm) in most cases, where electrons were prioritized to nitrite reductase because of the insufficient electron donor availability in the biofilm. In contrast, increasing effective diffusion coefficients did not pose a significant effect on electron competition and only increased electrons distributed to nitrite reductase when both NO 2- and N 2 O are added.
Pan, Y, Liu, Y, Wang, D & Ni, B-J 2019, 'Modeling effects of H2S on electron competition among nitrogen oxide reduction and N2O accumulation during denitrification', Environmental Science: Water Research & Technology, vol. 5, no. 3, pp. 533-542.
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A novel model was developed to describe electron competition during three-step denitrification through linking nitrogen reduction and carbon oxidation with electron carriers.
Pang, T, Zheng, G, Fang, J, Ruan, D & Sun, G 2019, 'Energy absorption mechanism of axially-varying thickness (AVT) multicell thin-walled structures under out-of-plane loading', Engineering Structures, vol. 196, pp. 109130-109130.
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© 2019 Elsevier Ltd Multicell columns have becoming increasingly attractive in crashworthiness applications due to their high efficiency of material utilization. Meanwhile, an urgent need exists to develop new structures to achieve the aim of light weight without sacrificing crashworthiness. A novel multicell column with axially-varying thickness (AVT) is proposed in this study. Quasi-static crushing tests were firstly performed experimentally to investigate crushing behaviors. Subsequently, corresponding numerical simulation models were built, validated, and used to conduct a parametric study. Finally, analytical equations for the mean crushing force for AVT multicell columns were derived and used to assess the crashworthiness of multicell columns according to SFE (super folding element) method. The numerical results agreed well with experimental results in terms of deformation mode and crushing forces, and the theoretical predictions were validated by the experimental results. It was concluded that the thickness gradient of AVT multicell columns could effectively reduce the initial peak crushing force while maintaining energy absorption capacity over a long crushing distance. From this perspective, the AVT multicell columns demonstrated competitive advantages over uniform columns as energy absorbers. Moreover, the analytical prediction could be a powerful tool for designing crashworthy structures.
Park, MJ, Lim, S, Gonzales, RR, Phuntsho, S, Han, DS, Abdel-Wahab, A, Adham, S & Shon, HK 2019, 'Thin-film composite hollow fiber membranes incorporated with graphene oxide in polyethersulfone support layers for enhanced osmotic power density', Desalination, vol. 464, pp. 63-75.
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© 2019 Elsevier B.V. This study focused on the development of pressure retarded osmosis (PRO) thin film composite (TFC) membranes for enhanced osmotic power using hollow fiber polyethersulfone (PES) support structure modified by incorporating hydrophilic graphene oxide (GO) nanosheets. The GO loadings in the hollow fiber substrates were varied to improve water flux performances without compromising the mechanical strength. GO embedded (≤0.2 wt%) PES hollow fiber supports revealed noticeable improvements in pure water permeability, improved structural morphologies, as well as the hydrophilicity within the support layer, without deteriorating the mechanical properties. The GO (0.2 wt%)-incorporated TFC-PRO membrane appeared to have an initial PRO flux (without any applied pressure) of 43.74 L m−2 h−1, lower specific reverse salt flux of 0.04 g L−1 and structural parameter (S) of 522 μm, significantly better than the control membrane. The maximum power density of 14.6 W m−2 was achieved at an operating pressure of 16.5 bar under the condition of DI water and 1 M NaCl as feed and draw solutions, respectively. The results obtained in this study indicate that modification of PRO hollow fiber support layer by incorporating nanoparticles such as GO nanosheet can be a useful tool to improve the PRO performance.
Pathirage, U, Indraratna, B, Pallewattha, M & Heitor, A 2019, 'A theoretical model for total suction effects by tree roots', Environmental Geotechnics, vol. 6, no. 6, pp. 353-360.
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Strengthening soft and weak soil by way of root reinforcement is a well-known strategy that is adopted worldwide. In Australia, native gum trees remain evergreen throughout the year and have been utilised to stabilise transportation corridors by way of reinforcement provided by the roots and the suction generated within the root domain as a function of evapotranspiration through the canopy. A mature gum tree can induce a missive total suction pressure exceeding 30 MPa through its root water and solute uptake in terms of matric plus osmotic suction. This cumulative effect of matric and osmotic suctions contributes to the overall shear strength of the soil, but the significant osmotic suction is often ignored in classical geotechnical engineering that does not consider the presence of trees. This study is an attempt to demonstrate the important role of osmotic suction, because it is directly proportional to the solute concentration in the soil and the solute uptake mechanisms of the surrounding vegetated ground.
Peng, L, Ngo, HH, Song, S, Xu, Y, Guo, W, Liu, Y, Wei, W, Chen, X, Wang, D & Ni, B-J 2019, 'Heterotrophic denitrifiers growing on soluble microbial products contribute to nitrous oxide production in anammox biofilm: Model evaluation', Journal of Environmental Management, vol. 242, pp. 309-314.
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© 2019 Elsevier Ltd In this work, a model framework was constructed to assess and predict nitrous oxide (N 2 O) production, substrate and microbe interactions in an anammox biofilm bioreactor. The anammox kinetics were extended by including kinetics of autotrophic soluble microbial products (SMP) formation, which consisted of utilization-associated products (UAP) and biomass-associated products (BAP). Heterotrophic bacteria growing on UAP, BAP and decay released substance (SS) were modelled to perform four-step sequential reductions from nitrate to dinitrogen gas. N 2 O was modelled as an intermidiate of heterotrophic denitrification via three pathways with UAP, BAP and SS as the electron donors. The developed model framework was evaluated using long-term operational data from an anammox biofilm reactor and satisfactorily reproduced effluent nitrogen and SMP as well as N 2 O emission factors under different operational conditions. The modeling results revealed that N 2 O was mainly produced with UAP as the electron donor while BAP and SS play minor roles. Heterotrophic denitrifiers growing on UAP would significantly contribute to N 2 O emission from anammox biofilm reactor even though heterotrophs only account for a relatively small fraction of active biomass in the anammox biofilm. Comprehensive simulations were conducted to investigate the effects of N loading rate and biofilm thickness, which indicated that maintaining a low N loading rate and a thick biofilm thickness were essential for high total nitrogen removal efficiency and low N 2 O emission.
Peng, Y, Wu, C, Li, J, Liu, J & Liang, X 2019, 'Mesoscale analysis on ultra-high performance steel fibre reinforced concrete slabs under contact explosions', Composite Structures, vol. 228, pp. 111322-111322.
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© 2019 Elsevier Ltd This paper develops a more efficient and applicable three-dimensional mesoscale model to simulate ultra-high performance steel fibre reinforced concrete (UHP-SFRC) slabs under contact explosions. In the proposed mesoscale model, UHP-SFRC consists of two components involving concrete matrix and steel fibres. The straight steel fibres are randomly distributed and orientated in the concrete matrix using the self-coding program. The proposed mesoscale model is firstly validated with a series of static and dynamic tests, and then it is adopted in the numerical simulation of contact explosions. With the verified mesoscale model, parametric studies are conducted to investigate the effects of slab thickness and TNT charge weight on the crater damage of UHP-SFRC slabs under contact explosions. Based on the results of parametric studies, a damage identification multi-classifier is constructed to recognize and predict the damage of UHP-SFRC slabs under contact explosions by using the support vector machine (SVM).
Pettit, T, Irga, PJ, Surawski, NC & Torpy, FR 2019, 'An Assessment of the Suitability of Active Green Walls for NO2 Reduction in Green Buildings Using a Closed-Loop Flow Reactor', Atmosphere, vol. 10, no. 12, pp. 801-801.
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Nitrogen dioxide (NO2) is a common urban air pollutant that is associated with several adverse human health effects from both short and long term exposure. Additionally, NO2 is highly reactive and can influence the mixing ratios of nitrogen oxide (NO) and ozone (O3). Active green walls can filter numerous air pollutants whilst using little energy, and are thus a candidate for inclusion in green buildings, however, the remediation of NO2 by active green walls remains untested. This work assessed the capacity of replicate active green walls to filter NO2 at both ambient and elevated concentrations within a closed-loop flow reactor, while the concentrations of NO and O3 were simultaneously monitored. Comparisons of each pollutant’s decay rate were made for green walls containing two plant species (Spathiphyllum wallisii and Syngonium podophyllum) and two lighting conditions (indoor and ultraviolet). Biofilter treatments for both plant species exhibited exponential decay for the biofiltration of all three pollutants at ambient concentrations. Furthermore, both treatments removed elevated concentrations of NO and NO2, (average NO2 clean air delivery rate of 661.32 and 550.8 m3∙h−1∙m−3 of biofilter substrate for the respective plant species), although plant species and lighting conditions influenced the degree of NOx removal. Elevated concentrations of NOx compromised the removal efficiency of O3. Whilst the current work provided evidence that effective filtration of NOx is possible with green wall technology, long-term experiments under in situ conditions are needed to establish practical removal rates and plant health effects from prolonged exposure to air pollution.
Phwan, CK, Chew, KW, Sebayang, AH, Ong, HC, Ling, TC, Malek, MA, Ho, Y-C & Show, PL 2019, 'Effects of acids pre-treatment on the microbial fermentation process for bioethanol production from microalgae', Biotechnology for Biofuels, vol. 12, no. 1.
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© 2019 The Author(s). Background: Microalgae are one of the promising feedstock that consists of high carbohydrate content which can be converted into bioethanol. Pre-treatment is one of the critical steps required to release fermentable sugars to be used in the microbial fermentation process. In this study, the reducing sugar concentration of Chlorella species was investigated by pre-treating the biomass with dilute sulfuric acid and acetic acid at different concentrations 1%, 3%, 5%, 7%, and 9% (v/v). Results: 3,5-Dinitrosalicylic acid (DNS) method, FTIR, and GC-FID were employed to evaluate the reducing sugar concentration, functional groups of alcohol bonds and concentration of bioethanol, respectively. The two-way ANOVA results (p < 0.05) indicated that there was a significant difference in the concentration and type of acids towards bioethanol production. The highest bioethanol yield obtained was 0.28 g ethanol/g microalgae which was found in microalgae sample pre-treated with 5% (v/v) sulfuric acid while 0.23 g ethanol/g microalgal biomass was presented in microalgae sample pre-treated with 5% (v/v) acetic acid. Conclusion: The application of acid pre-treatment on microalgae for bioethanol production will contribute to higher effectiveness and lower energy consumption compared to other pre-treatment methods. The findings from this study are essential for the commercial production of bioethanol from microalgae.
Pour, Park, Park, Hong, Muslim, Läufer, Crispini, Pradhan, Zoheir, Rahmani, Hashim & Hossain 2019, 'Landsat-8, Advanced Spaceborne Thermal Emission and Reflection Radiometer, and WorldView-3 Multispectral Satellite Imagery for Prospecting Copper-Gold Mineralization in the Northeastern Inglefield Mobile Belt (IMB), Northwest Greenland', Remote Sensing, vol. 11, no. 20, pp. 2430-2430.
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Several regions in the High Arctic still lingered poorly explored for a variety of mineralization types because of harsh climate environments and remoteness. Inglefield Land is an ice-free region in northwest Greenland that contains copper-gold mineralization associated with hydrothermal alteration mineral assemblages. In this study, Landsat-8, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and WorldView-3 multispectral remote sensing data were used for hydrothermal alteration mapping and mineral prospecting in the Inglefield Land at regional, local, and district scales. Directed principal components analysis (DPCA) technique was applied to map iron oxide/hydroxide, Al/Fe-OH, Mg-Fe-OH minerals, silicification (Si-OH), and SiO2 mineral groups using specialized band ratios of the multispectral datasets. For extracting reference spectra directly from the Landsat-8, ASTER, and WorldView-3 (WV-3) images to generate fraction images of end-member minerals, the automated spectral hourglass (ASH) approach was implemented. Linear spectral unmixing (LSU) algorithm was thereafter used to produce a mineral map of fractional images. Furthermore, adaptive coherence estimator (ACE) algorithm was applied to visible and near-infrared and shortwave infrared (VINR + SWIR) bands of ASTER using laboratory reflectance spectra extracted from the USGS spectral library for verifying the presence of mineral spectral signatures. Results indicate that the boundaries between the Franklinian sedimentary successions and the Etah metamorphic and meta-igneous complex, the orthogneiss in the northeastern part of the Cu-Au mineralization belt adjacent to Dallas Bugt, and the southern part of the Cu-Au mineralization belt nearby Marshall Bugt show high content of iron oxides/hydroxides and Si-OH/SiO2 mineral groups, which warrant high potential for Cu-Au prospecting. A high spatial distribution of hematite/jarosite, chalcedony/opal, and chlorite/epidote/bio...
Pramanik, BK, Hai, FI, Ansari, AJ & Roddick, FA 2019, 'Mining phosphorus from anaerobically treated dairy manure by forward osmosis membrane', Journal of Industrial and Engineering Chemistry, vol. 78, pp. 425-432.
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Provis, JL, Arbi, K, Bernal, SA, Bondar, D, Buchwald, A, Castel, A, Chithiraputhiran, S, Cyr, M, Dehghan, A, Dombrowski-Daube, K, Dubey, A, Ducman, V, Gluth, GJG, Nanukuttan, S, Peterson, K, Puertas, F, van Riessen, A, Torres-Carrasco, M, Ye, G & Zuo, Y 2019, 'RILEM TC 247-DTA round robin test: mix design and reproducibility of compressive strength of alkali-activated concretes', Materials and Structures, vol. 52, no. 5.
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AbstractThe aim of RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ is to identify and validate methodologies for testing the durability of alkali-activated concretes. To underpin the durability testing work of this committee, five alkali-activated concrete mixes were developed based on blast furnace slag, fly ash, and flash-calcined metakaolin. The concretes were designed with different intended performance levels, aiming to assess the capability of test methods to discriminate between concretes on this basis. A total of fifteen laboratories worldwide participated in this round robin test programme, where all concretes were produced with the same mix designs, from single-source aluminosilicate precursors and locally available aggregates. This paper reports the mix designs tested, and the compressive strength results obtained, including critical insight into reasons for the observed variability in strength within and between laboratories.
Pu, Y, Tang, J, Wang, XC, Hu, Y, Huang, J, Zeng, Y, Ngo, HH & Li, Y 2019, 'Hydrogen production from acidogenic food waste fermentation using untreated inoculum: Effect of substrate concentrations', International Journal of Hydrogen Energy, vol. 44, no. 50, pp. 27272-27284.
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© 2019 Hydrogen Energy Publications LLC The effect of substrate concentrations (0, 7.5, 15, 22.5, 30, and 37.5 g-VS/L) on hydrogen production from heat-treated and fresh food waste (FW) using untreated inoculums was investigated in this work. The highest hydrogen yield (75.3 mL/g-VS) was obtained with heat-treated FW at 15 g-VS/L. Lower substrate content could not provide enough organic matter for hydrogen fermentation, while higher substrate concentrations shifted the metabolic pathways from hydrogen fermentation to lactic acid fermentation by enriching the lactic acid bacteria (LAB), which lowered the slurry pH and decreased enzyme activity, resulting in a lower chemical oxygen demand (COD), volatile solid (VS), carbohydrate removal rate, and hydrogen yield. Compared with fresh FW, heat-treated FW is preferred for biohydrogen process with acetate as the main organic product. Additionally, at the optimal concentration (15 g-VS/L) using fresh FW, lactic acid is first accumulated and then degraded to produce hydrogen with butyrate as the main metabolite.
Punetha, P, Samanta, M & Mohanty, P 2019, 'Evaluation of the dynamic response of geosynthetic interfaces', International Journal of Physical Modelling in Geotechnics, vol. 19, no. 3, pp. 141-153.
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An accurate evaluation of interface friction between two geosynthetics under dynamic loading conditions is vital for the seismic design of landfills, flood protection systems and so on. This paper presents the results of an experimental investigation conducted on different geosynthetic–geosynthetic interfaces involving geomembrane and geotextile under static and dynamic loading conditions, using direct shear and shake table tests. The effect of normal stress, sliding velocity, frequency and the number of cycles on the dynamic coefficient of friction for the geosynthetic–geosynthetic interfaces has been investigated using a fixed-block set-up on a shake table. The results show that the dynamic coefficient of friction for geomembrane–geomembrane interfaces decreases with an increase in normal stress, sliding velocity and frequency. The dynamic coefficient of friction for geotextile–geotextile interfaces decreases with an increase in normal stress and frequency, while it increases with an increase in sliding velocity. However, the number of cycles has a negligible effect on the shear behaviour of all the interfaces tested.
Putra, N, Hakim, II, Erwin, FP, Abdullah, NA, Ariantara, B, Amin, M, Mahlia, TMI & Kusrini, E 2019, 'Development of a novel thermoelectric module based device for thermal stability measurement of phase change materials', Journal of Energy Storage, vol. 22, pp. 331-335.
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© 2019 Elsevier Ltd A recently developed method for the thermal stability measurement of phase-change materials (PCMs) involves thermal cycling using a thermoelectric module as a heating and cooling element. However, the utility of this approach was found to have some limitations, mainly because the thermoelectric polarity is changed according to time rather than the actual sample temperature. A method for thermal cycling test, where the thermoelectric polarity is automatically changed according to the sample temperature was developed in this study. In addition, a new cartridge design in this device requires a small sample volume (1.53 cm 3 ) and can be easily assembled and disassembled. This proposed device was tested on beeswax as a PCM sample. This is very important for savings PCMs material which usually expensive. The results showed that the apparatus had automatically cycled between the melting and cooling temperatures of beeswax. The thermal data showed that beeswax retains consistent melting and freezing temperatures after 1000 cycles, however, its heat of fusion degrades over repeated thermal cycling. This apparatus can be readily applied to study a wide range of PCMs for such as thermal energy storage materials for energy conservation. To our best knowledge, yet no study has been performed on this kind of equipment so far.
Putra, N, Rawi, S, Amin, M, Kusrini, E, Kosasih, EA & Indra Mahlia, TM 2019, 'Preparation of beeswax/multi-walled carbon nanotubes as novel shape-stable nanocomposite phase-change material for thermal energy storage', Journal of Energy Storage, vol. 21, pp. 32-39.
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© 2018 Elsevier Ltd Development of phase-change material (PCM) as thermal energy storage for building envelopes is promising for energy utilization. However, there are two major drawbacks of PCM application, which are low thermal conductivity and high-volume reduction due to phase-change transition. One solution is to develop a shape-stabilized phase-change material (SSPCM) as a composite that is able to prevent leakage during the transition from solid to liquid. Therefore, the objective of this study is to prepare beeswax/multi-walled carbon nanotubes as form-stable nanocomposite phase-change material for thermal energy storage, based on previously unattempted methods. Beeswax was being used as PCM because of its high latent heat and multi-walled carbon nanotubes (MWCNTs) as supporting material with high thermal conductivity. There are three types of MWCNTs applied in this research: pristine MWCNTs, ball-milled MWCNTs and acid-treated MWCNTs. Beeswax/CNT composite samples were prepared with ratios of 5 and 20 wt%. Composite samples were tested from structure modification and thermal performance, including latent heat, sensible heat, melting point, solidifying point, thermal conductivity, and thermal-cycle testing for up to 300 cycles. Experimental results showed that thermal conductivity of novel shape-stable nanocomposite PCM increased by a factor of 2 and there was no significant phase transition in the melting or solidifying temperature. The high heat storage capability and thermal conductivity of nanocomposite PCM enable it to be a potential material for thermal energy storage in practical applications.
Qi, Y, Indraratna, B & Coop, MR 2019, 'Predicted Behavior of Saturated Granular Waste Blended with Rubber Crumbs', International Journal of Geomechanics, vol. 19, no. 8, pp. 04019079-04019079.
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Qin, H & Stewart, MG 2019, 'System fragility analysis of roof cladding and trusses for Australian contemporary housing subjected to wind uplift', Structural Safety, vol. 79, pp. 80-93.
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This paper describes a reliability-based fragility method to evaluate the wind damage to roof cladding and trusses for contemporary houses in non-cyclonic regions of Australia. The fragility assessment considers roof sheeting loss and roof truss failure due to overloading of cladding-to-batten, batten-to-rafter/truss and rafter/truss-to-wall connectors that are typically the ‘weakest links’ of a roof system under wind uplift pressure. The wind fragility herein is expressed by the mean extent of roof sheeting loss and roof truss failures as a function of gust wind speed. Monte Carlo Simulation in conjunction with a finite element approach are employed to carry out the wind fragility assessment, which enables the probabilistic characterization of spatially varying wind uplift pressure, connection resistances, structural response, failure progression of roof connections and internal pressure evolution with increasing roof sheeting loss. The proposed fragility method was illustrated on representative contemporary housing built in Brisbane and Melbourne with complex hip-roof geometries and corrugated metal roof sheeting. It was found that, for the gust wind speed corresponding to a 500-year return period, the mean proportion of roof sheeting loss and roof truss failures is negligible for the representative contemporary house built in Melbourne, whereas considerable roof damage is predicted for those built in Brisbane when windward dominant openings exist.
Rahman, SMA, Mahila, TMI, Ahmad, A, Nabi, MN, Jafari, M, Dowell, A, Islam, MA, Marchese, AJ, Tryner, J, Brooks, PR, Bodisco, TA, Stevanovic, S, Rainey, T, Ristovski, ZD & Brown, RJ 2019, 'Effect of Oxygenated Functional Groups in Essential Oils on Diesel Engine Performance, Emissions, and Combustion Characteristics', Energy & Fuels, vol. 33, no. 10, pp. 9828-9834.
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Waste management cost for Australia is increasing every year, and thus, it is important to find alternative ways to use the waste. For example, essential oil has a significant waste stream that can be utilized in vehicles of their producers. However, some of the essential oils contain oxygen which considerably affects engine performance, emission, and combustion characteristics of diesel engines. Thus, this research paper will try to evaluate the essential oils as a replacement of diesel fuel to operate a multicylider diesel engine. For this study, two essential oils are selected which contain different oxygenated functional groups, tea tree oil (5.4% oxygen) and eucalyptus oil (8.4% oxygen), with an aim to evaluate the effect of these functional groups on engine performance and emission parameters. These oils were blended with neat diesel (0% oxygen) to obtain a blend cotaining 2.2% oxygen by weight. The blends produced similar brake power; however, brake-specific fuel consumption (BSFC) increased for eucalyptus oil blends (2.4-3.7%) and tea tree oil blends (3.9-5.3%). Essential oil-diesel blends resulted in less CO and increased NOX emission, produced similar peak pressure, and indicated mean effective pressure. The results then lead to the conclusion that oxygenated essential oils can have a role to reduce dependency of agricultural sector on diesel in the near future.
Rahmati, O, Samadi, M, Shahabi, H, Azareh, A, Rafiei-Sardooi, E, Alilou, H, Melesse, AM, Pradhan, B, Chapi, K & Shirzadi, A 2019, 'SWPT: An automated GIS-based tool for prioritization of sub-watersheds based on morphometric and topo-hydrological factors', Geoscience Frontiers, vol. 10, no. 6, pp. 2167-2175.
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© 2019 China University of Geosciences (Beijing) and Peking University The sub-watershed prioritization is the ranking of different areas of a river basin according to their need to proper planning and management of soil and water resources. Decision makers should optimally allocate the investments to critical sub-watersheds in an economically effective and technically efficient manner. Hence, this study aimed at developing a user-friendly geographic information system (GIS) tool, Sub-Watershed Prioritization Tool (SWPT), using the Python programming language to decrease any possible uncertainty. It used geospatial–statistical techniques for analyzing morphometric and topo-hydrological factors and automatically identifying critical and priority sub-watersheds. In order to assess the capability and reliability of the SWPT tool, it was successfully applied in a watershed in the Golestan Province, Northern Iran. Historical records of flood and landslide events indicated that the SWPT correctly recognized critical sub-watersheds. It provided a cost-effective approach for prioritization of sub-watersheds. Therefore, the SWPT is practically applicable and replicable to other regions where gauge data is not available for each sub-watershed.
Rahmawati, R, Bilad, MR, Laziz, AM, Nordin, NAHM, Jusoh, N, Putra, ZA, Mahlia, TMI & Jaafar, J 2019, 'Finned spacer for efficient membrane fouling control in produced water filtration', Journal of Environmental Management, vol. 249, pp. 109359-109359.
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© 2019 Elsevier Ltd Membrane based technologies are highly reliable for water and wastewater treatment, including for removal of total oil and grease from produced water. However, performances of the pressure driven processes are highly restricted by membrane fouling and the application of traditional air bubbling system is limited by their low shear stress due to poor contacts with the membrane surface. This study develops and assesses a novel finned spacer, placed in between vertical panel, for membrane fouling control in submerged plate-and-frame module system for real produced water filtration. Results show that permeability of the panel is enhanced by 87% from 201 to 381 L/(m2 h bar). The spacer system can be operated in switching mode to accommodate two-sided panel aeration. This leads to panel permeability increment by 22% higher than the conventional vertical system. The mechanisms of finned spacer in encouraging the flow trajectory was proven by visual observation and flow simulation. The fins alter the air bubbles flow trajectory toward the membrane surface to effectively scour-off the foulant. Overall results demonstrate the efficacy of the developed spacer in projecting the air bubble trajectory toward the membrane surface and thus significantly enhances membrane panel productivity.
Rana, HK, Akhtar, MR, Ahmed, MB, Liò, P, Quinn, JMW, Huq, F & Moni, MA 2019, 'Genetic effects of welding fumes on the progression of neurodegenerative diseases', NeuroToxicology, vol. 71, pp. 93-101.
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BACKGROUND:Welding involves exposure to fumes, gases and radiant energy that can be hazardous to human health. Welding fumes (WFs) comprise a complex mixture of metallic oxides, silicates and fluorides that may result in different health effects. Inhalation of WFs in large quantities over a long periods may pose a risk of developing neurodegenerative diseases (NDGDs), but the nature of this risk is poorly understood. To address this we performed transcriptomic analysis to identify links between WF exposure and NDGDs. METHODS:We developed quantitative frameworks to identify the gene expression relationships of WF exposure and NDGDs. We analyzed gene expression microarray data from fume-exposed tissues and NDGDs including Parkinson's disease (PD), Alzheimer's disease (AD), Lou Gehrig's disease (LGD), Epilepsy disease (ED) and multiple sclerosis disease (MSD) datasets. We constructed disease-gene relationship networks and identified dysregulated pathways, ontological pathways and protein-protein interaction sub-network using multilayer network topology and neighborhood-based benchmarking. RESULTS:We observed that WF associated genes share 18, 16, 13, 19 and 19 differentially expressed genes with PD, AD, LGD, ED and MSD respectively. Gene expression dysregulation along with relationship networks, pathways and ontologic analysis indicate that WFs may be linked to the progression of these NDGDs. CONCLUSIONS:Our developed network-based approach to analysis and investigate the genetic effects of welding fumes on PD, AD, LGD, ED and MSD neurodegenerative diseases could be helpful to understand the causal influences of WF exposure for the progression of the NDGDs.
Rana, HK, Akhtar, MR, Islam, MB, Ahmed, MB, Liò, P, Quinn, JMW, Huq, F & Moni, MA 2019, 'Genetic effects of welding fumes on the development of respiratory system diseases', Computers in Biology and Medicine, vol. 108, pp. 142-149.
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Rao, P, Zhao, L, Chen, Q & Nimbalkar, S 2019, 'Three-dimensional limit analysis of slopes reinforced with piles in soils exhibiting heterogeneity and anisotropy in cohesion', Soil Dynamics and Earthquake Engineering, vol. 121, pp. 194-199.
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© 2019 Elsevier Ltd Reinforcement of slopes by placing piles is one of the most common and effective techniques. Most of existing studies are limited to homogeneous and isotropic slopes, while in practice, the soil in the slope often exhibits heterogeneous and anisotropic characteristics. To address these issues, an innovative approach is introduced in this Technical Note to evaluate the stability of heterogeneous and anisotropic slopes incorporating the effect of anti-slide piles. Employing a three-dimensional upper-bound limit analysis, safety factor adopting the strength reduction technique is utilized herewith. The effects of soil heterogeneity and anisotropy with reference to cohesion on the optimal pile location and the slope stability in both cohesive-frictional and purely cohesive soils are investigated. The results amply demonstrate that the proposed limit analysis is appropriate for the stability assessment of reinforced slopes in heterogeneous and anisotropic soils. The safety factor increases with increase in heterogeneous factor and decrease in anisotropic factor. The optimal pile location is irrespective of these two factors, which should be carefully considered in engineering design.
Rao, P, Zhao, L, Chen, Q & Nimbalkar, S 2019, 'Three-Dimensional Slope Stability Analysis Incorporating Coupled Effects of Pile Reinforcement and Reservoir Drawdown', International Journal of Geomechanics, vol. 19, no. 4, pp. 06019002-06019002.
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© 2019 American Society of Civil Engineers. In pile-reinforced dams and bank slopes, the antislide effect of piles and drawdown of reservoirs are two aspects that could significantly affect the slope stability. However, existing studies have incorporated these two factors separately, albeit not in tandem. Moreover, stability assessment of these earth structures is usually performed ignoring the three-dimensional (3D) effect. To address these issues, the kinematic approach of limit analysis is adopted in this technical note for evaluating slope stability based on the 3D rotational failure mechanism. In addition, the coupled effects of pile reinforcement and water drawdown are considered. The analysis is performed for four types of drawdown cases. The results demonstrate that the optimal pile location undergoes significant change during the external drawdown process, while the effect of the declining water level on slope stability follows the similar pattern for varying pile locations.
Rasouli, H & Fatahi, B 2019, 'A novel cushioned piled raft foundation to protect buildings subjected to normal fault rupture', Computers and Geotechnics, vol. 106, pp. 228-248.
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© 2018 Elsevier Ltd Recent earthquake events have shown that besides the earthquake forces, interaction between the fault rupture and structure could cause a lot of damage to the surface and underground structures. Field observations have revealed a need to design structures for fault induced loading in regions with active faults. In this present study, three-dimensional numerical modelling using ABAQUS finite element software is used to study the interactive mechanism of normal fault rupture with a 20-story moment-resisting building frame sitting on a raft, connected piled raft, and cushioned piled raft foundations. The performance of a foundation-structure system is examined by considering geotechnical and structural performance objectives such as structural inter-story drift, raft displacement, and the bending moment and shear forces within the raft and piles. In order to improve the geotechnical and structural performance of foundations and buildings, a new foundation system with cushioned piles below the raft is proposed because of its superior performance with regards to raft rocking and permanent structural inter-story drifts under normal fault rupture. This proposed foundation system also curtailed the bending moments induced in the piles.
Rehman, J, Sohaib, O, Asif, M & Pradhan, B 2019, 'Applying systems thinking to flood disaster management for a sustainable development', International Journal of Disaster Risk Reduction, vol. 36, pp. 101101-101101.
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© 2019 Elsevier Ltd The rapid urbanization and environmental imbalance have significantly challenged Pakistan's organizational capacity to respond and initiate relief efforts and hence increasing its vulnerability to flood disaster situations. This study considers systems thinking approaches such as, Causal Loop Diagram (CLD) and Driver-Pressures-States-Impacts-Responses (DPSIR) framework to identify key stakeholders to disaster risk reduction and analyze various social, technical, institutional, cultural, infrastructural and environmental factors that contribute to flooding in Pakistan. Based on the information collected through expert interviews with key government officials and analyzing the existing literature and research reports on floods and disaster management, policy recommendations for long-term flood disaster response strategies have been made. The comprehensive set of recommendations towards effective flood management and mitigation would help build resilience from floods by raising community awareness and enhancing institutional capacities at federal, provincial and district government levels in the countries like Pakistan and other developing nations facing catastrophic flood situations.
Ren, J, Woo, YC, Yao, M, Lim, S, Tijing, LD & Shon, HK 2019, 'Nanoscale zero-valent iron (nZVI) immobilization onto graphene oxide (GO)-incorporated electrospun polyvinylidene fluoride (PVDF) nanofiber membrane for groundwater remediation via gravity-driven membrane filtration', Science of The Total Environment, vol. 688, pp. 787-796.
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Nanoscale zero-valent iron (nZVI), with its high reactivity towards a broad range of contaminants, has been a promising material for groundwater remediation. Membrane-supported nZVI can both avoid nZVI agglomeration for better reactivity and recycle nZVI to lower the risk of secondary pollution. In this study, we successfully fabricated a PVDF-GO membrane via electrospinning technology and employed the functionalized nanofiber membrane to immobilize nZVI particles. The addition of GO into PVDF nanofibers can both increase the hydrophilicity to improve membrane flux and offer -COOH as a binder to immobilize nZVI particles. PVDF-GO-nZVI membranes with different GO loadings (0%, 0.5%, 1%, 3% of PVDF) were tested with two typical nZVI-targeted contaminants (Cd(II) and trichloroethylene (TCE)) via gravity-driven membrane filtration. The results show that membrane with 1% GO had the best nZVI distribution against the aggregation and a better performance in both Cd removal (100%) and TCE removal (82%). The nZVI membrane had a high flux in gravity-driven filtration at 255 LMH for Cd(II) and 265 LMH for TCE respectively. Generally, the developed PVDF-GO-nZVI electrospun nanofiber membrane had an excellent performance in the gravity-driven membrane filtration system for groundwater remediation.
Ren, J, Yao, M, Woo, YC, Tijing, LD, Kim, J-H & Shon, HK 2019, 'Recyclable nanoscale zerovalent iron (nZVI)-immobilized electrospun nanofiber composites with improved mechanical strength for groundwater remediation', Composites Part B: Engineering, vol. 171, pp. 339-346.
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© 2019 Elsevier Ltd Nanoscale zero-valent iron (nZVI), as a promising material, has been widely used in groundwater remediation. Membrane-supported nZVI can both avoid nZVI agglomeration for better reactivity and recycle nZVI/contaminants to lower the risk of secondary pollution. However, membrane mechanical strength is a critical property for long-term operation and the regeneration of nZVI membranes. This study tried to use a high molecular weight dual-crosslinking method to improve the mechanical strength of polymeric electrospun nanofiber membranes. Specifically, high molecular weight polyacrylic acid (PAA, Mw = 450,000) was dual-crosslinked by adding polyvinyl alcohol (PVA) as covalent cross-linker (named as M450k) and Fe(II) or Fe(III) as the ionic cross-linker (named as M450k-II and M450k-III). The results indicated that the M450k had better thermal resistance against membrane shrinkage, thus having larger surface areas and more –COOH groups to immobilize more nZVI particles. Besides, M450k-III had the highest tensile strength at 8.5 MPa, 5 times the figure for the mono-crosslinked low molecular weight membrane (M2k). In terms of nZVI immobilization and filtration performance, the Fe(II)-crosslinked membrane had better nZVI immobilization with the highest removal capacity at 463 mg/g while Fe(III)-crosslinked membrane had overwhelming mechanical strength with decent and stable removal capacity under multiple nZVI regenerations over 15 filtration cycles. Generally, the high molecular weight Fe(III)-crosslinked PAA-PVA electrospun nZVI showed better potential for long-term filtration process.
Ren, Y, Ngo, HH, Guo, W, Ni, B-J & Liu, Y 2019, 'Linking the nitrous oxide production and mitigation with the microbial community in wastewater treatment: A review', Bioresource Technology Reports, vol. 7, pp. 100191-100191.
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© 2019 Elsevier Ltd Nitrous oxide (N2O) is largely produced during wastewater treatment. However, there is a lack of review on linking N2O production and mitigation with microbial communities in wastewater treatment. In this study, various microbial communities contributing to N2O turnovers are reviewed according to their functions in nitrogen cycle, including ammonia oxidizing bacteria and archaea, comammox bacteria, autotrophic denitrifying bacteria, heterotrophic denitrifying bacteria and non-denitrifying N2O reducers. Their metabolic pathways and enzymatic reactions of N2O production are demonstrated, including nitrifier denitrification, nitritation, archaeal N2O production and denitrification pathways. The N2O emission factor of the nitrifier denitrification pathway is generally higher than nitritation pathway, and that of denitrifying bacteria depends on species and electron acceptors. The mitigation strategies are developed according to the dominating microbial communities. Overall, this review illustrates a comprehensive characteristic of N2O production by microbial communities in wastewater treatment, which could contribute to the development of effective N2O mitigation strategies.
Reyhani, A, McKenzie, TG, Fu, Q & Qiao, GG 2019, 'Fenton‐Chemistry‐Mediated Radical Polymerization', Macromolecular Rapid Communications, vol. 40, no. 18, pp. e1900220-1900220.
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AbstractIn this review, the power of a classical chemical reaction, the Fenton reaction for initiating radical polymerizations, is demonstrated. The reaction between the Fenton reagents (i.e., Fe2+ and H2O2) generates highly reactive hydroxyl radicals, which can act as radical initiators for the polymerization of vinyl monomers. Since the Fenton reaction is fast, easy to set up, cheap, and biocompatible, this unique chemistry is widely employed in various polymer synthesis studies via free radical polymerization or reversible addition–fragmentation chain transfer polymerization, and is utilized in a wide range of applications, such as the fabrication of biomaterials, hydrogels, and core‐shell particles. Biologically activated Fenton‐mediated radical polymerization, which can be performed in aerobic environments, are particularly useful for applications in biomedical systems.
Reyhani, A, McKenzie, TG, Fu, Q & Qiao, GG 2019, 'Redox-Initiated Reversible Addition–Fragmentation Chain Transfer (RAFT) Polymerization', Australian Journal of Chemistry, vol. 72, no. 7, pp. 479-479.
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Reversible addition–fragmentation chain transfer (RAFT) polymerization initiated by a radical-forming redox reaction between a reducing and an oxidizing agent (i.e. ‘redox RAFT’) represents a simple, versatile, and highly useful platform for controlled polymer synthesis. Herein, the potency of a wide range of redox initiation systems including enzyme-mediated redox reactions, the Fenton reaction, peroxide-based reactions, and metal-catalyzed redox reactions, and their application in initiating RAFT polymerization, are reviewed. These redox-RAFT polymerization methods have been widely studied for synthesizing a broad range of homo- and co-polymers with tailored molecular weights, compositions, and (macro)molecular structures. It has been demonstrated that redox-RAFT polymerization holds particular promise due to its excellent performance under mild conditions, typically operating at room temperature. Redox-RAFT polymerization is therefore an important and core part of the RAFT methodology handbook and may be of particular importance going forward for the fabrication of polymeric biomaterials under biologically relevant conditions or in biological systems, in which naturally occurring redox reactions are prevalent.
Reyhani, A, Ranji-Burachaloo, H, McKenzie, TG, Fu, Q & Qiao, GG 2019, 'Heterogeneously Catalyzed Fenton-Reversible Addition–Fragmentation Chain Transfer Polymerization in the Presence of Air', Macromolecules, vol. 52, no. 9, pp. 3278-3287.
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© 2019 American Chemical Society. Aqueous Fenton-reversible addition-fragmentation chain transfer (RAFT) polymerization catalyzed by heterogeneous catalysts, that is, Fe(II) metal-organic framework (MOF) particles, coupled with hydrogen peroxide (H2O2) with the reaction mixture exposed to air in open vessels is reported. Reactive hydroxyl radicals are generated via a heterogeneous redox reaction between Fe(II) of the MOF particles and H2O2, which then chemically deoxygenate the reaction mixture in situ, initiating RAFT polymerization. Well-controlled polymers (Ä < 1.1) with experimental molecular weights close to theoretical values at high monomer conversions (ca. 85%) were achieved within 15 min. High 'livingness' of the synthesized polymer chains was demonstrated by chain extension experiments and matrix-assisted laser desorption/ionization time-of-flight analysis. This study contributes to the growing interest in nonenzymatic deoxygenation techniques via heterogeneous catalysis for conducting radical polymerization reactions.
Rizeei, H & Pradhan, B 2019, 'Urban Mapping Accuracy Enhancement in High-Rise Built-Up Areas Deployed by 3D-Orthorectification Correction from WorldView-3 and LiDAR Imageries', Remote Sensing, vol. 11, no. 6, pp. 692-692.
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Orthorectification is an important step in generating accurate land use/land cover (LULC) from satellite imagery, particularly in urban areas with high-rise buildings. Such buildings generally appear as oblique shapes on very-high-resolution (VHR) satellite images, which reflect a bigger area of coverage than the real built-up area on LULC mapping. This drawback can cause not only uncertainties in urban mapping and LULC classification, but can also result in inaccurate urban change detection. Overestimating volume or area of high-rise buildings has a negative impact on computing the exact amount of environmental heat and emission. Hence, in this study, we propose a method of orthorectfiying VHR WorldView-3 images by integrating light detection and ranging (LiDAR) data to overcome the aforementioned problems. A 3D rational polynomial coefficient (RPC) model was proposed with respect to high-accuracy ground control points collected from the LiDAR data derived from the digital surface model. Multiple probabilities for generating an orthrorectified image from WV-3 were assessed using 3D RCP model to achieve the optimal combination technique, with low vertical and horizontal errors. Ground control point (GCPs) collection is sensitive to variation in number and data collection pattern. These steps are important in orthorectification because they can cause the morbidity of a standard equation, thereby interrupting the stability of 3D RCP model by reducing the accuracy of the orthorectified image. Hence, we assessed the maximum possible scenarios of resampling and ground control point collection techniques to bridge the gap. Results show that the 3D RCP model accurately orthorectifies the VHR satellite image if 20 to 100 GCPs were collected by convenience pattern. In addition, cubic conventional resampling algorithm improved the precision and smoothness of the orthorectified image. According to the root mean square error, the proposed combination techni...
Rizeei, HM, Pradhan, B & Saharkhiz, MA 2019, 'Allocation of emergency response centres in response to pluvial flooding-prone demand points using integrated multiple layer perceptron and maximum coverage location problem models', International Journal of Disaster Risk Reduction, vol. 38, pp. 101205-101205.
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© 2019 The increases in the frequency and intensity of rainfall events due to global climate change and the development of additional pavement, roads and water storage sites due to population growth have enhanced the probability of pluvial flooding (PF) in urban areas. The estimation of urban pluvial flood vulnerability and prompt emergency responses are crucial steps towards urban planning and risk mitigation. However, uncertainties exist in the optimal allocation of emergency response centres (ERCs). This study assessed the current situation of ERCs in terms of PF-prone demand points. In this study, fire and police stations, hospitals and military camps were defined as ERCs, and residential buildings, where people spend most of their time, were considered demand points. Our study area was Damansara City in Peninsular Malaysia, which is frequently affected by PF. We combined an optimised PF probability model with ideal location allocation methods on a geographic information system platform to construct the proposed model for achieving accurate ERC spatial planning. Firstly, PF-prone urban areas were identified using a recent machine learning multiple layer perceptron (MLP) model. Then, a Taguchi method was used to calibrate the MLP variables, namely, seed, momentum, learning rate, hidden layer attribute and class. Fourteen important PF contributing parameters were weighted on the basis of historical flood events. The predicted PF-prone areas were validated by comparing the predictions with the data from meteorological stations and observed inventory events. In addition, the current locations of ERCs were utilised in the location allocation model to assess the ideal time for providing essential services to elements at risk. Minimum impedance and maximum coverage location problem models were implemented to assess the current allocated location of ERCs and multiple scenarios. The coverage of existing ERCs was calculated, and their suitable and optimal locations wer...
Rizeei, HM, Pradhan, B & Saharkhiz, MA 2019, 'An integrated fluvial and flash pluvial model using 2D high-resolution sub-grid and particle swarm optimization-based random forest approaches in GIS', Complex & Intelligent Systems, vol. 5, no. 3, pp. 283-302.
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Rizeei, HM, Pradhan, B, Saharkhiz, MA & Lee, S 2019, 'Groundwater aquifer potential modeling using an ensemble multi-adoptive boosting logistic regression technique', Journal of Hydrology, vol. 579, pp. 124172-124172.
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© 2019 Machine learning and data-driven models have achieved a favorable reputation in the field of advanced geospatial modeling, particularly for models of groundwater aquifer potential over large areas. Such models built using standalone machine learning techniques retain some uncertainty, including errors associated with the modeling process, sampling approach, and input hyper-parameters. Some of these techniques cannot be applied in data-scarce regions because high bias and variance can lead to oversimplification. Therefore, in the current study, we developed and validated a novel ensemble multi-adaptive boosting logistic regression (MABLR) model for groundwater aquifer potential mapping. This model was validated in a large area of the Gyeongsangbuk-do basin in South Korea and the results were compared to those of different types of machine learning models including multiple-layer perception (MPL), logistic regression (LR), and support vector machine (SVM) models. A forward stepwise LR technique was implemented to assess the importance of contributing morphological factors; we found 15 factors that contributed significantly: topographic wetness index (TWI), topographic roughness index (TRI), stream power index (SPI), topographic position index (TPI), multi-resolution valley bottom flatness (MVBF), slope, aspect, slope length (LS), distance from the river, distance from the fault, profile curvature, plane curvature, altitude, land use/land cover (LULC), and geology. We optimized the MABLR model using a fuzzy logic supervised (FLS) approach with 184 iterations and then validated the results using accuracy assessment metrics including the κ coefficient, root-mean-square error (RMSE), receiver operating characteristics (ROC), and the precision-recall curve (PRC). Our model had superior predictive performance among the models tested, with higher overall goodness-of-fit and validation values according to the κ coefficient (0.819 and 0.781, respectively), ROC (0.917...
Roodposhti, M, Aryal, J & Pradhan, B 2019, 'A Novel Rule-Based Approach in Mapping Landslide Susceptibility', Sensors, vol. 19, no. 10, pp. 2274-2274.
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Despite recent advances in developing landslide susceptibility mapping (LSM) techniques, resultant maps are often not transparent, and susceptibility rules are barely made explicit. This weakens the proper understanding of conditioning criteria involved in shaping landslide events at the local scale. Further, a high level of subjectivity in re-classifying susceptibility scores into various classes often downgrades the quality of those maps. Here, we apply a novel rule-based system as an alternative approach for LSM. Therein, the initially assembled rules relate landslide-conditioning factors within individual rule-sets. This is implemented without the complication of applying logical or relational operators. To achieve this, first, Shannon entropy was employed to assess the priority order of landslide-conditioning factors and the uncertainty of each rule within the corresponding rule-sets. Next, the rule-level uncertainties were mapped and used to asses the reliability of the susceptibility map at the local scale (i.e., at pixel-level). A set of If-Then rules were applied to convert susceptibility values to susceptibility classes, where less level of subjectivity is guaranteed. In a case study of Northwest Tasmania in Australia, the performance of the proposed method was assessed by receiver operating characteristics’ area under the curve (AUC). Our method demonstrated promising performance with AUC of 0.934. This was a result of a transparent rule-based approach, where priorities and state/value of landslide-conditioning factors for each pixel were identified. In addition, the uncertainty of susceptibility rules can be readily accessed, interpreted, and replicated. The achieved results demonstrate that the proposed rule-based method is beneficial to derive insights into LSM processes.
Ryu, S, Naidu, G, Hasan Johir, MA, Choi, Y, Jeong, S & Vigneswaran, S 2019, 'Acid mine drainage treatment by integrated submerged membrane distillation–sorption system', Chemosphere, vol. 218, pp. 955-965.
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Acid mine drainage (AMD), an acidic effluent characterized by high concentrations of sulfate and heavy metals, is an environmental and economic concern. The performance of an integrated submerged direct contact membrane distillation (DCMD) - zeolite sorption system for AMD treatment was evaluated. The results showed that modified (heat treated) zeolite achieved 26-30% higher removal of heavy metals compared to natural untreated zeolite. Heavy metal sorption by heat treated zeolite followed the order of Fe > Al > Zn > Cu > Ni and the data fitted well to Langmuir and pseudo second order kinetics model. Slight pH adjustment from 2 to 4 significantly increased Fe and Al removal rate (close to 100%) due to a combination of sorption and partial precipitation. An integrated system of submerged DCMD with zeolite for AMD treatment enabled to achieve 50% water recovery in 30 h. The integrated system provided a favourable condition for zeolite to be used in powder form with full contact time. Likewise, heavy metal removal from AMD by zeolite, specifically Fe and Al, mitigated membrane fouling on the surface of the hollow fiber submerged membrane. The integrated system produced high quality fresh water while concentrating sulfuric acid and valuable heavy metals (Cu, Zn and Ni).
Ryu, S, Naidu, G, Moon, H & Vigneswaran, S 2019, 'Selective copper extraction by multi-modified mesoporous silica material, SBA-15', Science of The Total Environment, vol. 697, pp. 134070-134070.
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© 2018 Selective copper (Cu) recovery from wastewater mitigates environmental pollution and is economically valuable. Mesoporous silica adsorbents, SBA-15, with amine-grafting (SBA-15-NH2) and manganese loading along with amine-grafting (Mn-SBA-15-NH2) were fabricated using KMnO4 and 3-aminopropyltriethoxysilane. The characteristics of the synthesized adsorbents were evaluated in detail in terms of its crystal structure peaks, surface area and pore size distribution, transmission electron microscope and X-ray photoelectron spectroscopy. The results established the 2.08 mmol/g of Cu adsorption capacity on Mn-SBA-15-NH2. Furthermore, in a mixed heavy metal solution, high selective Cu adsorption capacity on Mn-SBA-15-NH2 (2.01 mmol/g) was achieved while maintaining 96% adsorption amount as that of a single Cu solution. Comparatively, Cu adsorption on SBA-15-NH2 decreased by half due to high competition with other heavy metals. Optimal Cu adsorption occurred at pH 5. This pH condition enabled grafted amine group in Mn-SBA-15-NH2 to form strong chelating bonds with Cu, avoiding protonation of amine group (below pH 5) as well as precipitation (above pH 5). The adsorption equilibrium well fitted to Langmuir and Freundlich isotherm models, while kinetic results were represented by models of linear driving force approximation (LDFA) and pore diffusion model (PDM). High regeneration and reuse capacity of Mn-SBA-15-NH2 were well established by its capacity to maintain 90% adsorption capacity in a multiple adsorption-desorption cycle. Cu was selectively extracted from Mn-SBA-15-NH2 with an acid solution.
Saeidian, B, Mesgari, MS, Pradhan, B & Alamri, AM 2019, 'Irrigation Water Allocation at Farm Level Based on Temporal Cultivation-Related Data Using Meta-Heuristic Optimisation Algorithms', Water, vol. 11, no. 12, pp. 2611-2611.
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The present water crisis necessitates a frugal water management strategy. Deficit irrigation can be regarded as an efficient strategy for agricultural water management. Optimal allocation of water to agricultural farms is a computationally complex problem because of many factors, including limitations and constraints related to irrigation, numerous allocation states, and non-linearity and complexity of the objective function. Meta-heuristic algorithms are typically used to solve complex problems. The main objective of this study is to represent water allocation at farm level using temporal cultivation data as an optimisation problem, solve this problem using various meta-heuristic algorithms, and compare the results. The objective of the optimisation is to maximise the total income of all considered lands. The criteria of objective function value, convergence trend, robustness, runtime, and complexity of use and modelling are used to compare the algorithms. Finally, the algorithms are ranked using the technique for order of preference by similarity to ideal solution (TOPSIS). The income resulting from the allocation of water by the imperialist competitive algorithm (ICA) was 1.006, 1.084, and 1.098 times that of particle swarm optimisation (PSO), bees algorithm (BA), and genetic algorithm (GA), respectively. The ICA and PSO were superior to the other algorithms in most evaluations. According to the results of TOPSIS, the algorithms, by order of priority, are ICA PSO, BA, and GA. In addition, the experience showed that using meta-heuristic algorithms, such as ICA, results in higher income (4.747 times) and improved management of water deficit than the commonly used area-based water allocation method.
Sahoo, S, Dey, S, Dhar, A, Debsarkar, A & Pradhan, B 2019, 'On projected hydrological scenarios under the influence of bias-corrected climatic variables and LULC', Ecological Indicators, vol. 106, pp. 105440-105440.
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© 2019 Elsevier Ltd Assessing the impact of climate variability is important for water resources planning and management. In the present study, climate model data were utilized in conjunction with the hydrological model to analyze the effect of climate change on projected streamflow and groundwater recharge values for the Dwarakeswar-Gandherswari basin, India. Regional Climate Model (RCM) data [Representative Concentration Pathway (RCP 2.6, RCP 4.5, RCP 6 and RCP 8.5)] were considered for future climate change scenarios. Five bias correction methods [linear scaling (LS), local intensity scaling (LOCI), power transformation (PWTR), distribution mapping (DM) and variance scaling (VARI)] were applied for RCM based precipitation and temperature data. Projected Land Use and Land Cover (LULC) values were obtained from Dyna-CLUE model. Discharge data (1990–2016) was utilized for model calibration and validation purpose. Total twelve scenarios (4 RCPs per year for the years 2030, 2050 and 2080) were considered. The results showed increasing trend in simulated discharge for the months June to September and reverse trend for the months October to December. The results also showed that groundwater recharge increased for the maximum number of sub-watersheds for the interval 2016–2030 compared to 2016–2050 and 2016–2080 under all RCPs. Uncertainties in streamflow were quantified in terms of exceedance probability and recurrence interval. ALPHA_BF was the most sensitive parameter for the river basin. However, gross increase in groundwater recharge was observed for all the scenarios. These results can be effectively utilized for irrigation planning purpose.
Salmasi, F, Pradhan, B & Nourani, B 2019, 'Prediction of the sliding type and critical factor of safety in homogeneous finite slopes', Applied Water Science, vol. 9, no. 7.
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AbstractIn this paper, the effect of soil material parameters including soil specific weight (γ), cohesion (C), angle of internal friction ($$\emptyset$$∅), and geometric parameter of slope including angle with the horizontal (β) for a constant slope height (H) on factor of safety (Fs) was investigated.Fswas considered in two scenarios: (1) slope with dry condition, and (2) with steady-state saturated condition that comprises water level drawdown circumstances. In addition, the type of slip circle was also investigated. For this purpose, theSLOPE/Wsoftware as a subgroup ofGeo-Studiosoftware was implemented. Results showed that decreasing of water table level and omitting the hydrostatic pressure on the slope consequently would result in safety factor decrement. Comparison of the plane and circular failure surfaces showed that plane failure method produced good results for near-vertical slopes only. Determination of slip type showed that for state (30° < β < 45°), the three types of failure circles (toe, slope or midpoint circle) may occur. For state (45° < β < 60°), two modes of failure may occur: midpoint circle and toe circle. For state (β > 60°), the mode of failure circle is only toe circle. Linear and nonlinear regression equations were obtained for estimation of slope safety factor.
Samadi-Boroujeni, H, Altaee, A, Khabbaz, H & Zhou, J 2019, 'Application of buoyancy-power generator for compressed air energy storage using a fluid–air displacement system', Journal of Energy Storage, vol. 26, pp. 100926-100926.
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© 2019 Elsevier Ltd This study proposes a gravity power generator based on the fluid–air displacement system using Compressed Air Energy Storage from renewable energy sources to increase the solar and wind power system penetration in the power network. A computer model was applied to estimate the performance of the fluid–air displacement system, taking into account the effects of key design and operating parameters. Analysis of the system was performed to calculate the net energy generation as the difference between the energy input and the energy output. Simulation results indicated that the round-trip efficiency of the fluid–air displacement system was between 47% and 60%, assuming 80% compressor efficiency. Results also showed that a system generating the maximum energy density should have a speed of cylinders movement of 0.65 m/s, a cylinder-wall distance of 0.25 × diameter of the cylinder and a gap distance between centers of two tandem cylinders is equal to 1.25. Furthermore, a sensitivity analysis conducted on the main parameters of the system identified that the gap ratio and the buckets moving speed were the highly sensitive parameters to the design and operation of the proposed system. This study also demonstrates the feasibility of using the fluid-displacement system in energy storage from renewable energy technologies.
Samanta, M, Punetha, P, Sarkar, S, Dwivedi, A & Sharma, M 2019, 'Slope stability assessment and design of remedial measures for Tungnath Temple at Uttarakhand, India: a case study', Natural Hazards, vol. 96, no. 1, pp. 225-246.
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The present paper assesses the slope stability of the Tungnath Temple at Rudraprayag District, in the Indian state of Uttarakhand, and suggests the remedial measures. The temple is made of stone masonry and is believed to be over 1000 years old. Recently, signs of distress such as the development and subsequent widening of the cracks were observed on the walls of the temple. The field investigation reveals that the inadequate stability of the site, stagnation of water at the foundation level of the temple and poor drainage of the rainwater from the upper hill are the primary causes of distress for the temple. The factor of safety (FoS) values computed using the limit equilibrium method indicate that the site is marginally stable (FoS—0.8 to 1.0) under static condition and unstable (FoS—0.6 to 0.9) under the pseudo-static condition for a particular section. Thus, suitable control measures have been proposed to ensure the long-term stability of the site. The proposed control measures include the construction of a geosynthetic lined drain at critical locations and geosynthetic lining in the periphery of the temple to prevent the ingress of water. Additionally, the construction of two levels of gabion wall (6 m to 8 m high) at the periphery of the site has been proposed to improve the stability. The paper discusses the possible causes of the cracks, slope stability analysis and subsequently present the design details of the remedial measures for the long-term stability of the temple.
Sameen, MI & Pradhan, B 2019, 'Landslide Detection Using Residual Networks and the Fusion of Spectral and Topographic Information', IEEE Access, vol. 7, pp. 114363-114373.
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Sameen, MI, Pradhan, B & Lee, S 2019, 'Self-Learning Random Forests Model for Mapping Groundwater Yield in Data-Scarce Areas', Natural Resources Research, vol. 28, no. 3, pp. 757-775.
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© 2018, International Association for Mathematical Geosciences. Globally, groundwater plays a major role in supplying drinking water for urban and rural population and is used for irrigation to grow crops and in many industrial processes. A novel self-learning random forest (SLRF) model is developed and validated for groundwater yield zonation within the Yeondong Province in South Korea. This study was conducted with an inventory data initially divided randomly into 70% for training and 30% for testing and 13 groundwater-conditioning factors. SLRF was optimized using Bayesian optimization method. We also compared our method to other machine learning methods including support vector machine (SVM), artificial neural networks (ANN), decision trees (DT), and voting ensemble models. Model validation was accomplished using several methods, including a confusion matrix, receiver operating characteristics, cross-validation, and McNemar’s test. Our proposed self-learning method improves random forest (RF) generalization performance by about 23%, with SLRF success rates of 0.76 and prediction rates of 0.83. In addition, the optimized SLRF performed better [according to a threefold cross-validated AUC (area under curve) of 0.75] than that using randomly initialized parameters (0.57). SLRF outperformed all of the other models for the testing dataset (RF, SVM, ANN, DT, and Voted ANN-RF) when the overall accuracy, prediction rate, and cross-validated AUC metrics were considered. The SLRF also estimated the contribution of individual groundwater conditioning factors and showed that the three most influential factors were geology (1.00), profile curvature (0.97), and TWI (0.95). Overall, SLRF effectively modeled groundwater potential, even within data-scarce regions.
Samiran, NA, Chong, CT, Ng, J-H, Tran, M-V, Ong, HC, Valera-Medina, A, Chong, WWF & Mohd Jaafar, MN 2019, 'Experimental and numerical studies on the premixed syngas swirl flames in a model combustor', International Journal of Hydrogen Energy, vol. 44, no. 44, pp. 24126-24139.
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© 2019 Hydrogen Energy Publications LLC Experimental and numerical investigations were performed to study the combustion characteristics of synthesis gas (syngas) under premixed swirling flame mode. Four different type of syngases, ranging from low to high H2 content were tested and simulated. The global flame structures and post emission results were obtained from experimental work, providing the basis of validation for simulations using flamelet generated manifold (FGM) modelling approach via a commercial computational fluid dynamic software. The FGM method was shown to provide reasonable agreement with experimental result, in particular the post-exhaust emissions and global flame shapes. Subsequently, the FGM method was adopted to model the flame structure and predict the radical species in the reaction zones. Simulation result shows that H2-enriched syngas has lower peak flame temperature with lesser NO species formed in the reaction zone.
Sandi, SG, Saco, PM, Saintilan, N, Wen, L, Riccardi, G, Kuczera, G, Willgoose, G & Rodríguez, JF 2019, 'Detecting inundation thresholds for dryland wetland vulnerability', Advances in Water Resources, vol. 128, pp. 168-182.
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Sandu, S, Yang, M, Mahlia, TMI, Wongsapai, W, Ong, HC, Putra, N & Rahman, SMA 2019, 'Energy-Related CO2 Emissions Growth in ASEAN Countries: Trends, Drivers and Policy Implications', Energies, vol. 12, no. 24, pp. 4650-4650.
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The primary objective of this paper is to analyse the growth of energy-related CO2 emissions in ASEAN (Association of Southeast Asian Nations), with specific emphasis on identifying its trends and underlying drivers. This objective is premised on the arguments that: (1) there is a general lack of analysis of energy-related CO2 emissions growth across ASEAN countries; and (2) such an analysis is critical, because it could enable an assessment to be made of the efficacy of existing energy policies for reducing emissions. Decomposition analysis is the main approach adopted in this paper. The findings of this paper suggest that the growth of energy-related CO2 emissions has slowed in some major emitters in the region, due to energy efficiency improvement, and, to a lesser extent, a gradual switch in energy fuel mix towards lower emission sources (gas and renewables). However, this improvement is unlikely to drive a major transformation in the energy sectors of the region to the extent considered adequate for redressing the challenge of rising emissions, as indicated by a steady emissions growth in most ASEAN countries over the entire study period (1971–2016). By implication, this suggests that a significant scale-up of existing policy effort is needed to rectify the situations.
SarojiniAmma, BK, Indraratna, B & Vinod, JS 2019, 'A semi-empirical dilatancy model for ballast fouled with plastic fines', Geomechanics and Geoengineering, vol. 14, no. 1, pp. 12-17.
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© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. In the era of high speed trains, it is very important to ensure the stability of rail tracks under adverse conditions including the fouling of ballast. Fouling of ballast from unstable and saturated soft subgrade soil is one of the major reasons for track deterioration. The reported results of a number of large-scale laboratory experiments on the shear behaviour of ballast and fouled ballast are analysed, herein. It was observed that fines have a significant influence on the shear behaviour of ballast. Shear strength increases and dilatancy decreases with the addition of fines. In this paper, a semi-empirical mathematical model has been proposed to capture the dilatancy of ballast fouled with fines during shearing. The empirical constants a, b and c proposed in the model are a function of the fines content Void Contamination Index (VCI). The results of the model have been compared with the laboratory experiments and are found to be in good agreement.
Scott, M, Millar, GJ & Altaee, A 2019, 'Process design of a treatment system to reduce conductivity and ammoniacal nitrogen content of landfill leachate', Journal of Water Process Engineering, vol. 31, pp. 100806-100806.
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© 2019 Elsevier Ltd An innovative combination of computational modelling and laboratory testing was applied to address the challenge of reducing conductivity and ammoniacal nitrogen in landfill leachate. The hypothesis was that accelerated selection of an appropriate treatment process could be achieved by application of new water process engineering software termed AqMB. Several scenarios were investigated incorporating settling ponds, clarifiers, lime softening, ion exchange, pH adjustment and degassing unit operations. Settling ponds reduced the lime demand if a lime softening process was tested, albeit ponds involved greater expense and needed space. Alternately, a clarifier using aluminium chlorohydrate removed suspended solids. Use of a single cation resin bed in series with a strong base anion (SBA) resin column was not able to meet regulatory targets. However, employment of a weak acid cation (WAC) and strong acid cation (SAC) resin combination achieved very low ammoniacal nitrogen levels. To satisfy conductivity limits both a degassing unit and a strong base anion (SBA) resin were also necessary. Bench top testing of actual leachate confirmed that the software predicted the trends in water quality. Final solution conductivity of ca. 250 μS/cm and ammoniacal nitrogen content of <1 mg/l were recorded which were compliant with target values of <1600 μS/cm and <100 mg/l ammoniacal nitrogen. Process economics encompassing power, chemicals, and resin costs were calculated to be A$10.50 per kL leachate.
Shakor, P, Nejadi, S & Paul, G 2019, 'A Study into the Effect of Different Nozzles Shapes and Fibre-Reinforcement in 3D Printed Mortar', Materials, vol. 12, no. 10, pp. 1708-1708.
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Recently, 3D printing has become one of the most popular additive manufacturing technologies. This technology has been utilised to prototype trial and produced components for various applications, such as fashion, food, automotive, medical, and construction. In recent years, automation also has become increasingly prevalent in the construction field. Extrusion printing is the most successful method to print cementitious materials, but it still faces significant challenges, such as pumpability of materials, buildability, consistency in the materials, flowability, and workability. This paper investigates the properties of 3D printed fibre-reinforced cementitious mortar prisms and members in conjunction with automation to achieve the optimum mechanical strength of printed mortar and to obtain suitable flowability and consistent workability for the mixed cementitious mortar during the printing process. This study also considered the necessary trial tests, which are required to check the mechanical properties and behaviour of the proportions of the cementitious mix. Mechanical strength was measured and shown to increase when the samples were printed using fibre-reinforced mortar by means of a caulking gun, compared with the samples that were printed using the same mix delivered by a progressive cavity pump to a 6 degree-of-freedom robot. The flexural strength of the four-printed layer fibre-reinforced mortar was found to be 3.44 ± 0.11 MPa and 5.78 ± 0.02 MPa for the one-layer. Moreover, the mortar with different types of nozzles by means of caulking is printed and compared. Several experimental tests for the fresh state of the mortar were conducted and are discussed.
Shakor, P, Nejadi, S, Paul, G & Malek, S 2019, 'Review of Emerging Additive Manufacturing Technologies in 3D Printing of Cementitious Materials in the Construction Industry', Frontiers in Built Environment, vol. 4, pp. 1-17.
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Additive manufacturing is a fabrication technology that is rapidly revolutionizing the manufacturing and construction sectors. In this paper, a review of various prototyping technologies for printing cementitious materials and selected 3D printing techniques are presented in detail. Benchmark examples are provided to compare three well-known printing techniques; inkjet printing (binder jetting), selected laser sintering (SLS), and extrusion printing (extrusion based process). A comprehensive search in the literature was conducted to identify various mix designs that could be employed when printing cementitious materials. Aspects of concrete mix design are described, and some new experiments are conducted to analyse the printability of new mixes by the authors. Future research in the area of the rheology of cementitious materials and its relationship with the structural performance of finished concretes are highlighted.
Shakor, P, Nejadi, S, Paul, G, Sanjayan, J & Aslani, F 2019, 'Heat curing as a means of postprocessing influence on 3D printed mortar specimens in powderbased 3D printing', Indian Concrete Journal, vol. 93, no. 9, pp. 65-74.
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Inkjet (Powder-based) three-dimensional printing (3DP) shows significant promise in concrete construction applications. The accuracy, speed, and capacity to build complicated geometries are the most beneficial features of inkjet 3DP. Therefore, inkjet 3DP needs to be carefully studied and evaluated with construction goals in mind and employed in real-world applications, where it is most appropriate. This paper focuses on the important aspect of curing 3DP specimens. It discusses the enhanced mechanical properties of the mortar that are unlocked through a heat-curing process. Experiments were conducted on cubic mortar specimens that were printed and cured in an oven at a range of different temperatures (40, 60, 80, 90, 100°C). The results of the experimental tests showed that 80°C is the optimum heat-curing temperature to achieve the highest compressive strength and flexural strength of the printed mortar specimens. These tests were performed on two different dimensions of the cubic specimens, namely, 20x20x20 mm, 50x50x50 mm and on prism specimens with dimensions of 160x40x40 mm. The inkjet 3DP process and the post-processing curing are discussed. In addition, 3D scanning of the printed specimens was employed and the surface roughness profiles of the 3DP gypsum specimens and cement mortar are recorded 13.76 µm and 22.31 µm, respectively.
Shakor, P, Nejadi, S, Paul, G, Sanjayan, J & Nazari, A 2019, 'Mechanical Properties of Cement-Based Materials and Effect of Elevated Temperature on 3-D Printed Mortar Specimens in Inkjet 3-D Printing', ACI Materials Journal, vol. 116, no. 2, pp. 55-67.
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Copyright © 2019, American Concrete Institute. All rights reserved. Three-dimensional (3-D) printers have the potential to print samples that can be used as a scaffold for a variety of applications in different industries. In this paper, cement-based materials including ordinary portland cement, calcium aluminate cement (passing 150 µm [0.0059 in.] size sieve), and fine sand were investigated as the cement-based materials in inkjet 3-D printing. Prism specimens were printed for the three-point bending test; and cubic specimens were printed for the uniaxial compressive strength test. Prism samples were printed along different directional axes (X, Y, and Z). The tests were conducted at different saturation levels (water-cement ratio [w/c]) as represented by S100C200, S125C250, S150C300, and S170C340. The prism specimens were cured in water for 7 and 28 days while cubic specimens were cured in Ca(OH) 2 and water for 7 and 28 days at the same ambient temperatures. In general, the results changed according to the directional axes of the prisms. However, following water curing, the cubic samples were heated up to 40°C (104°F) in an oven and a higher compressive strength was evident compared to the samples which were only cured in the room-temperature water. The wettability test for both powders has been conducted in the presented study.
Shao, R, Wu, C, Su, Y, Liu, Z, Liu, J & Xu, S 2019, 'Numerical analysis on impact response of ultra-high strength concrete protected with composite materials against steel ogive-nosed projectile penetration', Composite Structures, vol. 220, pp. 861-874.
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© 2019 Elsevier Ltd In order to investigate the impact behaviours of ultra-high strength concrete (UHSC) target protected with high-toughness lightweight energy absorption composite materials against the projectile penetration thoroughly, a numerical study using LS-DYNA is conducted at impact velocities between 540 m/s and 810 m/s. The major compositions of FE models are the same as those of experimental specimens which include steel wire mesh reinforced concrete (SWMRC) plates, UHMWPE fibre laminates, aluminium foam sheets and the protected UHSC. Numerical results involving depth of penetration (DOP), impact crater (exfoliated) diameter of SWMRC plates, localized damage and ballistic deviation of the projectiles are obtained and then compared with experimental data, where the numerical results show reasonable agreement with the test results. Based on the validated FE models, the projectile penetration process and the energy evolution between the target and the projectile are studied. In addition, a parametric analysis is conducted to investigate the influence of the arrangement order for present composite materials on DOP and impact resistance of reinforced UHSC target, as well as the ballistic deviation and deformation of the projectile. Results of this study indicate that for the current UHSC target, firstly, the ballistic deviation and projectile deformation are two important factors affecting the impact resistance of the target; secondly, the fibre laminates play a major role in the projectile ballistic deviation and the impact kinetic energy of the projectile is mainly absorbed by the concrete matrix, multilayer steel wire meshes and different densities of foam sheets.
Shao, R, Wu, C, Su, Y, Liu, Z, Liu, J, Chen, G & Xu, S 2019, 'Experimental and numerical investigations of penetration resistance of ultra-high strength concrete protected with ceramic balls subjected to projectile impact', Ceramics International, vol. 45, no. 6, pp. 7961-7975.
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© 2019 Elsevier Ltd and Techna Group S.r.l. Ceramic materials characterized by high hardness, high inherent strength, low density and excellent dimensional stability have been extensively applied in the design of high-performance and lightweight protective structures to resist the high-speed projectile impact. In order to study the anti-penetration capability of ceramic balls protected ultra-high strength concrete (CB-UHSC), high-speed projectile impact tests were conducted at striking velocities of 545 m/s, 679 m/s, and 809 m/s to investigate the impact performance of ceramic balls, projectiles, and the protected UHSC. The experimental results indicated the effectiveness and economy of ceramic balls in resisting the high-speed projectile impact. Numerical studies were then conducted to reproduce the projectile penetration process within CB-UHSC targets with the assistance of LS-DYNA. Based on the validated numerical models, impact resistance and ballistic deviation of projectiles, as well as the energy evolution between projectiles and targets, were further investigated to comprehensively understand the impact performance of this newly designed protective structure under projectile penetration.
Sharma, M, Samanta, M & Punetha, P 2019, 'Experimental Investigation and Modeling of Pullout Response of Soil Nails in Cohesionless Medium', International Journal of Geomechanics, vol. 19, no. 3, pp. 04019002-04019002.
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Sheikhrahimi, A, Pour, AB, Pradhan, B & Zoheir, B 2019, 'Mapping hydrothermal alteration zones and lineaments associated with orogenic gold mineralization using ASTER data: A case study from the Sanandaj-Sirjan Zone, Iran', Advances in Space Research, vol. 63, no. 10, pp. 3315-3332.
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© 2019 COSPAR The Sanandaj-Sirjan Zone (SSZ) is considered as an important region for gold exploration in the western sector of Iran. Its mountainous topography and unpaved routes make its study challenging for researchers and raise the costs for mining companies strating new exploration plans. Gold mineralization mainly occurs as irregular to lenticular sulfide-bearing quartz veins along shear zones in deformed mafic to intermediate metavolcanic and metasedimentary rocks. In this investigation, ASTER data are used for mapping hydrothermal alteration minerals and to better discriminate geological structural features associated with orogenic gold occurrences in the area. Image transformation techniques such as specialized band ratioing and Principal Component Analysis are used to delineate lithological units and alteration minerals. Supervised classification techniques, namely Spectral Angle Mapper (SAM) and Spectral Information Divergence (SID) are applied to detect subtle differences between indicator alteration minerals associated with ground-truth gold locations in the area. The directional filtering technique is applied to help in tracing along the strike the different linear structures. Results demonstrate that the integration of image transformation techniques and supervised classification of ASTER data with fieldwork and geochemical exploration studies has a great efficiency in targeting new prospects of gold mineralization in the SSZ. The approach used in this research provides a fast, cost-efficient means to start a comprehensive geological and geochemical exploration programs in the study area and elsewhere in similar regions.
Shit, RC, Sharma, S, Puthal, D, James, P, Pradhan, B, Moorsel, AV, Zomaya, AY & Ranjan, R 2019, 'Ubiquitous Localization (UbiLoc): A Survey and Taxonomy on Device Free Localization for Smart World', IEEE Communications Surveys & Tutorials, vol. 21, no. 4, pp. 3532-3564.
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© 1998-2012 IEEE. The 'Smart World' envisioned by technology will be achieved by the penetration of intelligence into ubiquitous things, including physical objects, cyber-entities, social-elements or individuals, and human thinking. The development of Smart World is enabled by diverse applications of wireless sensor networks (WSNs) into those components identified as things. Such a smart-world will have features controlled significantly by the location information. Control and Policy information of Smart World services, often addressed as location-based services (LBSs), are governed by location data. Localization thus becomes the key enabling technology for Smart World facilities. It is generally classified as active and passive techniques in nature. Active localization is a widely adopted localization scheme where the target is detected and tracked carries a tag or attached device. The other category, Passive methods, defines targets to be localized as free of carrying a tag or device, hence also referred to as device-free localization (DFL) or sensor-less localization. The passive approach is a well suited for the development of diverse smart world applications with ubiquitous localization. DFL schemes fall into a wide range of application scenarios within the Smart World ecosystem. A few notable examples are occupancy detection, identity definition, positioning, gesture detection, activity monitoring, pedestrian and vehicle-traffic flow surveillance, security safeguarding, ambient intelligence-based systems, emergency rescue operations, smart work-spaces and patient or elderly monitoring. In this paper, the revolution of DFL technologies have been reviewed and classified comprehensively. Further, the emergence of the Smart World paradigm is analyzed in the context of DFL principles. Moreover, the inherent challenges within the application domains have been extensively discussed and improvement strategies for multi-target localization and counting approach are ...
Silitonga, A, Mahlia, T, Shamsuddin, A, Ong, H, Milano, J, Kusumo, F, Sebayang, A, Dharma, S, Ibrahim, H, Husin, H, Mofijur, M & Rahman, S 2019, 'Optimization of Cerbera manghas Biodiesel Production Using Artificial Neural Networks Integrated with Ant Colony Optimization', Energies, vol. 12, no. 20, pp. 3811-3811.
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Optimizing the process parameters of biodiesel production is the key to maximizing biodiesel yields. In this study, artificial neural network models integrated with ant colony optimization were developed to optimize the parameters of the two-step Cerbera manghas biodiesel production process: (1) esterification and (2) transesterification. The parameters of esterification and transesterification processes were optimized to minimize the acid value and maximize the C. manghas biodiesel yield, respectively. There was excellent agreement between the average experimental values and those predicted by the artificial neural network models, indicating their reliability. These models will be useful to predict the optimum process parameters, reducing the trial and error of conventional experimentation. The kinetic study was conducted to understand the mechanism of the transesterification process and, lastly, the model could measure the physicochemical properties of the C. manghas biodiesel.
Silitonga, AS, Mahlia, TMI, Kusumo, F, Dharma, S, Sebayang, AH, Sembiring, RW & Shamsuddin, AH 2019, 'Intensification of Reutealis trisperma biodiesel production using infrared radiation: Simulation, optimisation and validation', Renewable Energy, vol. 133, pp. 520-527.
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© 2018 Elsevier Ltd Biodiesel production using intensification of methyl ester is becoming very important due to its considerably lower energy requirement and shorter reaction time in obtaining feedstock oil. The present study investigated utilisation of Reutealis trisperma oil to produce biodiesel. A Box-Behnken experimental design was used to optimise the transesterification process. The process variables were explored and the optimum methanol to oil molar ratio, catalyst concentration, reaction temperature, and reaction time were 8:1, 1.2 wt%, 64 °C and 68 min respectively and the corresponding methyl ester yield was 98.39%. The experiment was conducted in triplicate to validate the quadratic model. Results showed average methyl ester yield was 97.78%, which is close to the predicted value, indicating reliability of the model. Results also indicated that using infrared radiation method has many advantageous, such as less energy consumption as a result of deeper penetration of reactant mass which can improve mass transfer between the immiscible reactants in order to improve quality of biodiesel. The physicochemical properties of Reutealis trisperma methyl ester produced under optimum transesterification process variables were also measured and the properties fulfilled the fuel specifications as per ASTM D6751 and EN 14214 standards.
Skilodimou, HD, Bathrellos, GD, Chousianitis, K, Youssef, AM & Pradhan, B 2019, 'Multi-hazard assessment modeling via multi-criteria analysis and GIS: a case study', Environmental Earth Sciences, vol. 78, no. 2.
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© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. Multi-hazard assessment modeling comprises an essential tool in any plan that aims to mitigate the impact of future natural disasters. For a particular area they can be generated by combining assessment maps for different types of natural hazards. In the present study, the analytical hierarchy process (AHP) supported by a Geographical Information System (GIS) was utilized to initially produce assessment maps on hazards from landslides, floods and earthquakes and subsequently to combine them into a single multi-hazard map. Evaluation of the reliability of the proposed model predictions was performed through uncertainty analysis of the variables that we used for producing the final model. The drainage basin of Peneus (Pinios) River (Western Peloponnesus, Greece), an area that is prone to landslides, floods and seismic events, was selected for the implementation of the aforementioned approach. Our findings revealed that the high hazard zones are mainly distributed in the western and north-eastern part of the region under investigation. The calculated multi-hazard map, which corresponds to the potential urban development suitability map of the study area, was classified into five classes, namely of very low, low, moderate, high and very high suitability. The most suitable areas for urban development are distributed mostly in the eastern part, in agreement with the low and very low hazard level for the three considered natural hazards. In addition, by performing uncertainty analysis we showed that the spatial distribution of the suitability zones does not change significantly. Ultimately, the final map was verified using the actual inventory of landslides and floods that affected the study area. In this context, we showed that 80% of the landslide occurrences and all the recorded flood events fall within the boundaries of the moderate, low and very low suitability zones. Consequently, the predictive capaci...
Smit, R & Kingston, P 2019, 'Measuring On-Road Vehicle Emissions with Multiple Instruments Including Remote Sensing', Atmosphere, vol. 10, no. 9, pp. 516-516.
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The objective of this paper is to use remote sensing to measure on-road emissions and to examine the impact and usefulness of additional measurement devices at three sites. Supplementing remote sensing device (RSD) equipment with additional equipment increased the capture rate by almost 10%. Post-processing of raw data is essential to obtain useful and accurate information. A method is presented to identify vehicles with excessive emission levels (high emitters). First, an anomaly detection method is applied, followed by identification of cold start operating conditions using infrared vehicle profiles. Using this method, 0.6% of the vehicles in the full (enhanced) RSD data were identified as high emitters, of which 35% are likely in cold start mode where emissions typically stabilize to low hot running emission levels within a few minutes. Analysis of NOx RSD data confirms that poor real-world NOx performance of Euro 4/5 light-duty diesel vehicles observed around the world is also evident in Australian measurements. This research suggests that the continued dieselisation in Australia, in particular under the current Euro 5 emission standards and the more stringent NO2 air quality criteria expected in 2020 and 2025, could potentially result in local air quality issues near busy roads.
Smit, R, Kingston, P, Neale, DW, Brown, MK, Verran, B & Nolan, T 2019, 'Monitoring on-road air quality and measuring vehicle emissions with remote sensing in an urban area', Atmospheric Environment, vol. 218, pp. 116978-116978.
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Simultaneous day-time measurement (8 a.m.–5 p.m.) of on-road air quality and emissions (remote sensing) on an urban road with traffic volumes varying between approximately 400-800 vehicles per hour and an average speed of about 40 km/h has been used to compare multiple measurement techniques and assess on-road air quality. It was found that observed daytime concentration levels of CO, NO , NO , O , PM and PM are below current WHO health based guideline values, varying from a few percent (CO) to above 60% (O and PM ) of the guideline values. NO to NO ratios were about a factor of two higher than measured in a previous tunnel study, which indicates that about half of measured NO concentrations are due to urban background levels. Statistical analysis suggest that on-road NO and ozone concentrations are largely driven by atmospheric chemistry processes, and not significantly affected by variation in local traffic volume and fleet mix. A significant positive weighted correlation (r = 0.71–0.74) between remote sensing and air concentration monitoring is observed for CO in calm conditions. Speciated VOC measurements on the road show large discrepancies with current COPERT (Australia) vehicle emission factors, confirming the results from an earlier tunnel study. The weight of evidence suggests that the current (EU based) VOC speciation in COPERT Australia is likely not appropriate for the Australian on-road fleet. x 2 3 10 2.5 3 2.5 2 x 2 2
Song, J-H, Shon, HK, Wang, P, Jang, A & Kim, IS 2019, 'Tuning the nanostructure of nitrogen-doped graphene laminates for forward osmosis desalination', Nanoscale, vol. 11, no. 45, pp. 22025-22032.
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Studies have concentrated on the physicochemical properties of graphene-based membranes that can replace polymeric membranes for use in forward osmosis (FO) systems.
Song, K, Yeerken, S, Li, L, Sun, J & Wang, Q 2019, 'Improving Post-Anaerobic Digestion of Full-Scale Anaerobic Digestate Using Free Ammonia Treatment', ACS Sustainable Chemistry & Engineering, vol. 7, no. 7, pp. 7171-7176.
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© 2019 American Chemical Society. Post-anaerobic digestion of full-scale anaerobic digestate (AD) is used in enhancing sludge reduction in some sewage treatment plants (STPs). However, the AD degradation is usually inhibited due to its slow hydrolysis rate and low degradability. This study presents an innovative pretreatment method by using free ammonia (FA, i.e., NH 3 ) to improve post-anaerobic digestion full-scale AD degradation. The FA treatment at over 360 mg NH 3 -N/L for 24 h has improved AD degradation with the highest solubilization (0.1 mg chemical oxygen demand (COD)/mg volatile solids (VS), at 850 mg NH 3 -N/L), being 5.3 times that without pretreatment (0.019 mg COD/mg VS). After 8 days of post-anaerobic digestion, non-pretreated AD has degraded 8.5%, while the FA pretreated AD at 360-850 mg NH 3 -N/L has degraded 9.9-10.9%, representing a relative increase of 14-22%. The mathematical model captured the tested data well with R 2 > 0.994 in all cases, and the model revealed that AD degradation improvement was attributed to an increase in AD degradation percentage. Economic analysis shows that the FA pretreatment method could be economically favorable in enhancing full-scale AD post-anaerobic digestion.
Song, Z, Zhang, X, Ngo, HH, Guo, W, Song, P, Zhang, Y, Wen, H & Guo, J 2019, 'Zeolite powder based polyurethane sponges as biocarriers in moving bed biofilm reactor for improving nitrogen removal of municipal wastewater', Science of The Total Environment, vol. 651, no. Pt 1, pp. 1078-1086.
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This study aims to enhance nitrogen removal efficiency of a moving bed biofilm reactor (MBBR) by developing a new MBBR with zeolite powder-based polyurethane sponges as biocarriers (Z-MBBR). Results indicated the total nitrogen (TN) removal efficiency and simultaneous nitrification and denitrification (SND) performance in Z-MBBR were nearly 10% higher than those in the conventional MBBR with sponges as biocarriers (S-MBBR). About 84.2 ± 4.8% of TN was removed in Z-MBBR compared to 75.1 ± 6.8% in S-MBBR. Correspondingly, the SND performance in Z-MBBR and S-MBBR was 90.7 ± 4.1% and 81.7 ± 6.5%, respectively. The amount of biofilm attached to new biocarriers (0.470 ± 0.131 g/g carrier) was 1.3 times more than that of sponge carriers (0.355 ± 0.099 g/g carrier). Based on the microelectrode measurements and microbial community analysis, more denitrifying bacteria existed in the Z-MBBR system, and this can improve the SND performance. Consequently, this new Z-MBBR can be a promising option for a hybrid treatment system to better nitrogen removal from wastewater.
Song, Z, Zhang, X, Ngo, HH, Guo, W, Wen, H & Li, C 2019, 'Occurrence, fate and health risk assessment of 10 common antibiotics in two drinking water plants with different treatment processes', Science of The Total Environment, vol. 674, pp. 316-326.
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© 2019 Elsevier B.V. The occurrence of antibiotics in drinking water has become a serious problem worldwide as they are a potential and real threat to human health. In this study, the variability of 10 typical antibiotics in two drinking water plants was investigated in two seasons (n = 12). The total concentrations of target antibiotics in raw water were significantly higher in winter than in summer, which may be attributed to the more frequent occurrence of colds and respiratory diseases as well as less rainfall in winter. The efficiency in removing the antibiotics varied from −46.5% to 45.1% in water plant A (WP-A) using a conventional process and 40.3% to 70.3% in water plant B (WP-B) with an advanced treatment process. Results indicated that the antibiotics in WP-A were mainly removed via the coagulation process. However in WP-B, the ultraviolet + chlorination process played a key role in antibiotics removal, followed by the pre-ozone + coagulation process. According to the human health risk assessment, it was suggested that the risk of drinking water was significantly higher than that of skin contact. However, the risk of carcinogenesis and non-carcinogenesis caused by antibiotics was at an acceptable level.
Stewart, MG 2019, 'Reliability-based load factors for airblast and structural reliability of reinforced concrete columns for protective structures', Structure and Infrastructure Engineering, vol. 15, no. 5, pp. 634-646.
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Reliability-based design allows the decision-maker to select the level of reliability for a specific explosive blast loading scenario. Important to this is an understanding of airblast and resistance uncertainty. Reliability-based load factors are calculated and are dependent on the variability of model error, explosive mass and range. Reliability-based design load factors (RBDFs) are estimated for explosive ordnance, terrorism, weaponeering and other scenarios. The effect of RBDFs on structural reliabilities for reinforced concrete (RC) columns is then calculated where resistance and loading are random variables, and compared to target values. It was found, for realistic combinations of range and explosive mass variabilities, that RC columns designed to existing standards have a significant margin of safety with a probability of failure of 1 × 10 −3 to 1 × 10 −5 . However, if there is large airblast variability, then the application of RBDFs is necessary to ensure that safety levels are acceptable according to international standards.
Stewart, MG & Netherton, MD 2019, 'A probabilistic risk-acceptance model for assessing blast and fragmentation safety hazards', Reliability Engineering & System Safety, vol. 191, pp. 106492-106492.
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There are many circumstances where decision-makers consider risks associated with explosions – from either natural or deliberate events – where the goal is clarity with respect to the actual safety and hazard risks posed to society and its people, systems and infrastructure. The paper describes how probabilistic safety and hazard modelling of blast and fragmentation can better inform a Quantitative Explosive Risk assessment (QERA). A QERA may be used to define an explosive safety distance based on the risk of explosive hazards being less than a societal acceptable risk. The concepts are illustrated with scenarios at a generic explosives ordnance (EO) site. In one scenario we demonstrate that current, deterministically based, regulations in Australia and internationally may be overly conservative. In other words, a deterministic based regulation may show that a building is located in an unsafe area, whereas a QERA can show, for the same building, that fatality risks are less than those deemed acceptable by society. Another example demonstrates the significant effect that uncertainty modelling, particularly that associated with post-detonation blast-loads, has on fatality risks.
Stewart, MG, Dorrough, B & Netherton, MD 2019, 'Field testing and probabilistic assessment of ballistic penetration of steel plates for small calibre military ammunition', International Journal of Protective Structures, vol. 10, no. 4, pp. 421-438.
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The penetration of projectiles into semi-infinite targets helps in the understanding and modelling of terminal ballistics. The article describes field test results of 5.56×45 mm F1 Ball and 7.62×51 mm M80 Ball ammunition. The targets were 25-mm-thick mild and high strength steel plates of Grade 250 MPa and 350 MPa, respectively. The tests recorded penetration depth, muzzle and impact velocities, and bullet mass. Despite its smaller calibre, the 5.56 mm × 45 mm F1 Ball ammunition recorded deeper penetrations than the larger calibre 7.62 mm × 51 mm M80 Ball ammunition. This is due to the 5.56 mm ammunition comprising a hardened steel penetrator and lead core, whereas the 7.62 mm ammunition comprised only a lead core. Multiple shots were fired for each type of munition. The coefficient of variation of steel penetration is approximately 0.10 and 0.03 for 5.56 mm and 7.62 mm rounds, respectively. The article also presents predictive models of steel penetration depth and compares these to the field test results.
Stuart, BH, Maynard-Casely, HE, Booth, N, Leung, AE & Thomas, PS 2019, 'Neutron diffraction of deuterated tripalmitin and the influence of shear on its crystallisation', Chemistry and Physics of Lipids, vol. 221, pp. 108-113.
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© 2019 This neutron diffraction study of deuterated tripalmitin has provided further insight into a forensic observation of the crystallisation of lipids under high-shear conditions. To achieve this, an experimental set up was designed to enable simultaneous rheological data from a Couette cell to be recorded with neutron powder diffraction, enabling the influence of shear on the polymorph transformation on cooling to be monitored in real time. Tripalmitin was observed to directly transform from a liquid phase to a β polymorph under the influence of shear. Although the liquid to β transition was not observed to be influenced by shear rate, the degree of crystallinity, qualitatively denoted by an increase in the sharpness of the diffraction peaks, was observed at higher shear rates. Evidence is also presented that the rate of cooling influences the ordering in the β-polymorph produced in zero shear conditions.
Stuart, BH, Thomas, PS, Barrett, M & Head, K 2019, 'Modelling clay materials used in artworks: an infrared spectroscopic investigation', Heritage Science, vol. 7, no. 1.
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Abstract Modelling clays are utilised by artists for their malleable properties. One of the challenges in managing collections containing such materials is the variety of commercial compositions available and, therefore, the variation in the requirements for storage and maintenance of such artefacts. The Art Gallery of New South Wales in Australia is responsible for the care of a range of artworks that contain modelling materials, some of which show detrimental property changes and there is concern for the longevity of such works. The aim of the current research is to determine the compositions of the modelling materials utilised in works produced by different artists in the gallery’s collection. Infrared spectroscopy was used to identify the main constituents of samples collected from the works of four different artists and a variety of material types were determined. Oil-based, air-hardening and polymer clays of varying composition were identified in the survey of artworks. Signs of deterioration in particular artworks were able to be characterised using spectroscopy, with the mechanisms identified including loss and oxidation of the oil component. Where a polymer clay was chosen by one artist, the distortion of the artwork was due to flow of the material over time and demonstrates the need for an understanding of the long term properties of the materials being used. The study has highlighted the need for conservators to have a detailed understanding of modelling materials to ensure the longevity of artworks containing this class of materials.
Su, D, Zhang, QH, Ngo, HH, Dzakpasu, M, Guo, WS & Wang, XC 2019, 'Development of a water cycle management approach to Sponge City construction in Xi'an, China', Science of The Total Environment, vol. 685, pp. 490-496.
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In recent years, climate change, population growth, and inefficient use of water have exacerbated the water resources scarcity problems around the world. Hence, this paper establishes a new approach of Sponge City construction (SCC) based on water cycle management (WCM) for the sustainable exploitation of groundwater, recycled wastewater and rainwater in the Xi'an Siyuan University. The University is located in an isolated area that is far away from the city center so that no centralized water supply system could be utilized. To mitigate water scarcity problems in the University, 39% of the annual rainfall is harvested and stored from impervious surfaces and grasslands by using the Curve Number (CN) method. This stored water is reused for non-potable purposes: 40% for toilet flushing and 60% as miscellaneous water. According to findings, the available rainwater of500-700 m3/d accounts for 16-23% of the non-potable water from April to December. Moreover, the utilization rate of water resources increases from 204% to 227%. With the minimum volume of large-scale rainwater harvesting cistern of 52,760 m3, the environment could be adequately watered while improving the expansion and development conditions on the campus. Furthermore, water scarcity problems could be mitigated through optimization of the water resources utilization system. This study demonstrates that this new approach of SCC based on WCM could alleviate water resources scarcity problems in Xi'an Siyuan University effectively. It is hoped that this study will provide a model and example of the new approach for future applications.
Sullivan, C, Thomas, P & Stuart, B 2019, 'An atomic force microscopy investigation of plastic wrapping materials of forensic relevance buried in soil environments', Australian Journal of Forensic Sciences, vol. 51, no. 5, pp. 596-605.
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© 2018 Australian Academy of Forensic Sciences Plastics are one means of disposal of items or remains associated with criminal activity. The surface characteristics of plastic wrapping materials of forensic interest in soil environments have been investigated to determine the environmental factors that have the greatest influence on the degradation process of such polymers. Polyethylene bags and poly(vinyl chloride) sheeting were buried in model environments encompassing different soil types, moisture content, pH and temperature. Atomic force microscopy was used to monitor the changes to the polymer surface at a nanometre level. Over a two-year burial period, the degradation of polyethylene was found to be enhanced by an increased moisture content and an elevated soil pH. The plasticizer content of poly(vinyl chloride) was affected by burial and was observed to leach from the plastic in all environments continually over the burial period. A moist environment was shown to have a more pronounced effect on the removal of plasticizer. A measurement of the surface roughness of plastics using atomic force microscopy has been shown to be sensitive to the burial environment and demonstrates the potential of this technique to measure relatively subtle changes to burial items exposed to different environments.
Sun, G, Zhang, J, Li, S, Fang, J, Wang, E & Li, Q 2019, 'Dynamic response of sandwich panel with hierarchical honeycomb cores subject to blast loading', Thin-Walled Structures, vol. 142, pp. 499-515.
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© 2019 Elsevier Ltd This paper introduces a novel hierarchical core structure to sandwich panel for bearing the blast loading, in which each vertex of a regular hexagonal cell was replaced with a smaller hexagonal unit. The finite element (FE) models of such hierarchical honeycomb sandwich panels were established and validated with the experiments under different impulse loads. The hierarchical honeycomb cores were compared with the regular honeycomb counterpart in terms of the peak deflection on the back facesheet, compression and specific energy absorption (SEA) of the core. The results showed that the maximum deflection at the back facesheet of the hierarchical honeycomb sandwich panels were smaller than the regular honeycomb counterpart for a higher level of blast load (specifically, the dimensionless impulse higher than 0.06). It was found that the structural hierarchical parameter γ (i.e. the ratio of the newly-introduced smaller hexagonal edge length (L1) to the regular hexagon edge length (L0)), had limited influence on the maximum deflection of back facesheet of the sandwich panel, but had a significant effect on the SEA of the cores.
Sun, J, Dai, X, Wang, Q, van Loosdrecht, MCM & Ni, B-J 2019, 'Microplastics in wastewater treatment plants: Detection, occurrence and removal', Water Research, vol. 152, pp. 21-37.
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© 2018 Elsevier Ltd Microplastics have aroused increasing concern as they pose threats to aquatic species as well as human beings. They do not only contribute to accumulation of plastics in the environment, but due to absorption they can also contribute to spreading of micropollutants in the environment. Studies indicated that wastewater treatment plants (WWTPs) play an important role in releasing microplastics to the environment. Therefore, effective detection of the microplastics and understanding their occurrence and fate in WWTPs are of great importance towards microplastics control. In this review, the up-to-date status on the detection, occurrence and removal of microplastics in WWTPs are comprehensively reviewed. Specifically, the different techniques used for collecting microplastics from both wastewater and sewage sludge, and their pretreatment and characterization methods are reviewed and analyzed. The key aspects regarding microplastics occurrence in WWTPs, such as concentrations, total discharges, materials, shapes and sizes are summarized and compared. Microplastics removal in different treatment stages and their retention in sewage sludge are explored. The development of potential microplastics-targeted treatment technologies is also presented. Although previous researches in microplastics have undoubtedly improved our level of understanding, it is clear that much remains to be learned about microplastics in WWTPs, as many unanswered questions and thereby concerns still remain; some of these important future research areas are outlined. The key challenges appear to be to harmonize detection methods as well as microplastics mitigation from wastewater and sewage sludge.
Sun, L, Fang, H, Cai, Q, Yang, X, He, J, Zhou, JL & Wang, X 2019, 'Sediment load change with erosion processes under simulated rainfall events', Journal of Geographical Sciences, vol. 29, no. 6, pp. 1001-1020.
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© 2019, Science Press Springer-Verlag. It is of great significance to quantify sediment load changing with erosion processes for improving the precision of soil loss prediction. Indoor rainfall experiments were conducted in 2 rainfall intensities (90 mm·h−1 and 120 mm·h−1), four slope gradients (17.60%, 26.80%, 36.40%, 46.60%) and 2 slope lengths (5 m, 10 m). Erosion processes are divided into five stages. Results show that sediment yield is mainly sourced from rill erosion, contributing from 54.60% to 95.70% and the duration of which is extended by slope gradients. Sediment load and sediment concentration are significantly different along erosion stages, with the highest values in rill development stage (SIV). Surface flow velocities (interrill and rill) demonstrate less significant differences along erosion stages. Rainfall intensity increases sediment load in all stages, with up to 12.0 times higher when changing from 90 to 120 mm·h−1. There is an increasing trend for sediment load and sediment concentration with the rising slope gradient, however, fluctuations existed with the lowest values on 26.80% and 36.40%, respectively, among different treatments. The slope gradient effects are enhanced by rainfall intensity and slope length. Results from this study are important for validating and improving hillslope erosion modelling at each erosion stage.
Sun, Q, Indraratna, B & Heitor, A 2019, 'Behaviour of a capping layer reinforced with recycled tyres', Proceedings of the Institution of Civil Engineers - Ground Improvement, vol. 172, no. 3, pp. 127-137.
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In this paper, a sustainable approach for reducing lateral displacement in a track by increasing the confining pressure in the track substructure is demonstrated by placing a cellular rubber (tyre) membrane infilled with crushed ballast, as an alternative to a traditional capping layer of compacted granulates. Plate-load tests on a single tyre filled with gravel and subjected to a vertical load were carried out to investigate the interaction between tyre and gravel. A track model with tyre reinforcement was created to evaluate the performance of a tyre-reinforced capping layer under cyclic loading, and a numerical model was developed to determine the benefit that tyres would provide to railway substructure, especially when spent ballast is recycled as capping layer materials.
Sun, Q, Indraratna, B & Ngo, NT 2019, 'Effect of increase in load and frequency on the resilience of railway ballast', Géotechnique, vol. 69, no. 9, pp. 833-840.
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This paper presents the results of a series of large-scale cyclic triaxial tests conducted on ballast subjected to increased load and frequency of loading. For a given loading, the laboratory test data demonstrate that the resilient modulus of ballast is influenced by the frequency of loading. Both strain hardening and strain softening can be observed in response to increasing magnitude of load and frequency. A correlation between the resilient modulus and bulk stress is introduced to describe both the strain-hardening and strain-softening behaviour of ballast under different frequencies. A good corroboration between the cyclic stress ratio and the accumulated permanent strain and the resilient strain is demonstrated.
Sun, Y & Nimbalkar, S 2019, 'Stress-fractional soil model with reduced elastic region', Soils and Foundations, vol. 59, no. 6, pp. 2007-2023.
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Sun, Y, Nimbalkar, S & Chen, C 2019, 'Particle breakage of granular materials during sample preparation', Journal of Rock Mechanics and Geotechnical Engineering, vol. 11, no. 2, pp. 417-422.
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© 2019 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences Particle breakage is commonly observed in granular materials when subjected to external loads. It was found that particle breakage would occur during both sample preparation and loading stages. However, main attention was usually paid to the particle breakage behaviour of samples during loading stage. This study attempts to explore the breakage behaviour of granular materials during sample preparation. Triaxial samples of rockfill aggregates are prepared by layered compaction method to achieve different relative densities. Extents of particle breakage based on the gradings before and after test are presented and analysed. It is found that particle breakage during sample preparation cannot be ignored. Gradings after test are observed to shift away from the initial grading. Aggregates with larger size that appear to break are more than the smaller-sized ones. Irrespective of the initial gradings, an increase in the extent of particle breakage with the increasing relative density is observed during sample preparation.
Sun, Y, Wang, C, Guo, G, Fu, Q, Xiong, Z, Li, D & Liu, Y 2019, 'Facile synthesis of highly efficient photocatalysts based on organic small molecular co-catalyst', Applied Surface Science, vol. 469, pp. 553-563.
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© 2018 Elsevier B.V. A new metal-free organic molecular as co-catalyst was developed, which could drastically enhance the photocatalytic performance of photocatalyst (eg. g-C 3 N 4 , MoS 2 and TiO 2 ). The enhancing photocatalytic activity was evaluated for photocatalytic degradation of organic dyes. It showed ultra-high photocatalytic rate (4.17 mg/g·min) and ultra-short time (about 6.0 min) for photocatalytic degradation of organic dyes (25 mg/ml). The enhanced photocatalytic performance was attributed to suppress recombination of photogenerated charges and provide a new photoredox reaction pathway under molecular co-catalyst assistance. The study represents a facile method to develop ultra-effectively photocatalyst for applications in production of green and renew-able energy carrier, H 2 from water, reduction of CO 2 , synthesis of fine chemicals and remediation of environmental pollutants.
Surindra, M, Caesarendra, W, Prasetyo, T, Mahlia, T & Taufik 2019, 'Comparison of the Utilization of 110 °C and 120 °C Heat Sources in a Geothermal Energy System Using Organic Rankine Cycle (ORC) with R245fa, R123, and Mixed-Ratio Fluids as Working Fluids', Processes, vol. 7, no. 2, pp. 113-113.
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Binary cycle experiment as one of the Organic Rankine Cycle (ORC) technologies has been known to provide an improved alternate scenario to utilize waste energy with low temperatures. As such, a binary geothermal power plant simulator was developed to demonstrate the geothermal energy potential in Dieng, Indonesia. To better understand the geothermal potential, the laboratory experiment to study the ORC heat source mechanism that can be set to operate at fixed temperatures of 110 °C and 120 °C is conducted. For further performance analysis, R245fa, R123, and mixed ratio working fluids with mass flow rate varied from 0.1 kg/s to 0.2 kg/s were introduced as key parameters in the study. Data from the simulator were measured and analyzed under steady-state condition with a 20 min interval per given mass flow rate. Results indicate that the ORC system has better thermodynamic performance when operating the heat source at 120 °C than those obtained from 110 °C. Moreover, the R123 fluid produces the highest ORC efficiency with values between 9.4% and 13.5%.
Tan, SX, Lim, S, Ong, HC & Pang, YL 2019, 'State of the art review on development of ultrasound-assisted catalytic transesterification process for biodiesel production', Fuel, vol. 235, no. Energy Convers Manage 128 2016, pp. 886-907.
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© 2018 Elsevier Ltd Excessive utilization of petroleum diesel has led to severe environmental pollution. Biodiesel, which is greener and renewable, can be a potential alternative fuel. Biodiesel is produced through transesterification reaction between vegetable oil, animal fat or even waste cooking oil (WCO) and alcohol in the presence of catalyst. Under process intensification, ultrasonic irradiation is employed in the transesterification reaction to enhance the agitation between immiscible reactants. Besides providing intensive mixing, it also offers uniform heating due to the localized temperature increase and formation of micro jets from the transient collapse of cavitation bubbles, thus reducing the energy consumption. The focus of this paper is to review the recent research progress on the ultrasound-assisted catalytic transesterification of non-edible vegetable oils using homogeneous and heterogeneous catalysts. The primary factors that affect the operation and efficiency of ultrasound-assisted transesterification such as alcohol to oil molar ratio, catalyst loading, reaction time, reaction temperature, energy consumption, phase separation time, ultrasonic pulse mode and biodiesel conversion or yield have been reviewed. The highlights of this review paper are the provisions on the mechanism of ultrasonic reactive extraction (RE) in the biodiesel production, kinetic study and the existing pilot reactors on the ultrasound-assisted transesterification which are still rarely reviewed in the current literature. Lastly, the challenges and feasibility for future development in the process intensification of biodiesel production are also addressed.
Tan, SX, Lim, S, Ong, HC, Pang, YL, Fitranto, K, Goh, BHH & Chong, CT 2019, 'Two-step catalytic reactive extraction and transesterification process via ultrasonic irradiation for biodiesel production from solid Jatropha oil seeds', Chemical Engineering and Processing - Process Intensification, vol. 146, pp. 107687-107687.
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Tan, SX, Ong, HC, Lim, S, Pang, YL & Milano, J 2019, 'Process intensification of biodiesel synthesis via ultrasound‐assisted in situ esterification of Jatropha oil seeds', Journal of Chemical Technology & Biotechnology, vol. 94, no. 5, pp. 1362-1373.
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AbstractBACKGROUNDNon‐edible oil such as Jatropha oil has high free fatty acids (FFAs) content. Therefore, acid esterification is a suitable route to reduce its FFA content to an acceptable limit (2 FFA%) before being subjected to further transesterification. In the present study, Jatropha seeds were utilized as the feedstock directly instead of Jatropha oil during ultrasound‐assisted in situ esterification. The objective of this work is to evaluate the feasibility of in situ esterification of Jatropha oil seeds using sulphuric acid (H2SO4) as catalyst with the aid of ultrasound.RESULTSThe reaction parameters (particle size, n‐hexane to methanol volume ratio, H2SO4 amount, reaction time and ultrasonic amplitude) were optimized and evaluated in term of extraction and esterification efficiencies as well as fatty acid methyl ester (FAME) yield. The highest extraction efficiency of 83.96%, esterification efficiency of 71.10% and FAME yield of 38.58% were achieved at particle size of 1–2 mm, n‐hexane to methanol volume ratio of 3:1, 5 vol% of H2SO4 and ultrasonic amplitude of 60% with reaction time of 150 min.CONCLUSIONSynthesis of biodiesel via ultrasound‐assisted in situ esterification of Jatropha oil seeds was successful with considerable yield, which could provide improvement in terms of process intensification and more value added by‐products. © 2018 Society of Chemical Industry
Tang, J, Pu, Y, Wang, XC, Hu, Y, Huang, J, Ngo, HH, Pan, S, Li, Y & Zhu, N 2019, 'Effect of additional food waste slurry generated by mesophilic acidogenic fermentation on nutrient removal and sludge properties during wastewater treatment', Bioresource Technology, vol. 294, pp. 122218-122218.
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Fermentation slurry from food waste (FSFW) generated by acidogenic fermentation at mesophilic temperature was utilized to improve the nutrients removal from wastewater. Organic acids (such as lactate and volatile fatty acids) in the FSFW behaved as readily biodegradable carbon sources, while the particulate and macromolecular organics acted as slowly biodegradable carbon sources during denitrification processes. The FSFW dosage significantly influenced the nitrogen removal performance, and a C/N ratio (in terms of chemical oxygen demand to nitrogen ratio) of 8 could achieve complete denitrification in the batch tests. In a sequencing batch reactor (SBR) using FSFW for long-term wastewater treatment, extracellular polymeric substances (EPS) gradually accumulated, sludge particle size significantly increased, and microbial communities were selectively enriched, which contributed to promoting the nitrogen (>80%) and phosphate (90.1%) removal efficiencies. Overall, the FSFW produced by acidogenic fermentation under mesophilic temperature served as an excellent intermediary between FW valorization and wastewater treatment.
Tang, J, Wang, XC, Hu, Y, Pu, Y, Huang, J, Ngo, HH, Zeng, Y & Li, Y 2019, 'Nutrients removal performance and sludge properties using anaerobic fermentation slurry from food waste as an external carbon source for wastewater treatment', Bioresource Technology, vol. 271, pp. 125-135.
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Enhancement of nitrogen and phosphate removal using thermophilic fermentation slurry from food waste (FSFW) as external carbon source was investigated. Based on the batch tests, the soluble and particulate fractions of the FSFW acted as easily and slowly biodegradable carbon sources, respectively, and the fermented slurry showed the combined nutrients removal properties of soluble and solid organics. During the long-term operation of a sequencing batch reactor (SBR) with FSFW for wastewater treatment, the sludge particle size increased obviously, the bacterial metabolic capacity improved significantly, and some functional microorganisms were enriched selectively, which significantly promoted the nitrogen removal efficiency (approximately 90%) by enhancing the anoxic denitrification and simultaneous nitrification and denitrification (SND) processes. Moreover, high phosphate removal efficiency (above 98%) was achieved through the aerobic and anoxic phosphate accumulation processes. Thus, using the FSFW as supplementary carbon source is a suitable solution for both food waste disposal and wastewater treatment.
Tang, Z, Hu, Y, Tam, VWY & Li, W 2019, 'Uniaxial compressive behaviors of fly ash/slag-based geopolymeric concrete with recycled aggregates', Cement and Concrete Composites, vol. 104, pp. 103375-103375.
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© 2019 Elsevier Ltd The uniaxial compressive stress-strain behaviors of fly ash/ground granulated blast furnace slag (GGBFS) geopolymeric concrete containing recycled aggregate were investigated in this study. Geopolymeric concretes with the variations of three recycled aggregate replacement ratios (i.e., 0%, 50% and 100%) and four contents of slag (i.e., 0%, 10%, 20% and 30% of the mass of total binder) were tested under uniaxial compression. Special attention was devoted to the failure behaviors and patterns, stress-strain characteristics (such as the peak stress, the elastic modulus, the peak strain, and the ultimate strain) and energy absorption capacity. The results showed that the peak stress, elastic modulus and energy absorption (toughness) decreased with the increase of the replacement ratio of recycled aggregate, while these mechanical properties increased when the content of slag increased. The reverse trend was observed with respect to the ductility. Moreover, the inclusion of slag could alleviate the nagative effects of the recycled aggregate replacement on the stress-strain characteristics of geopolymeric concrete. Additionally, a stress-strain model was developed in this study by modifying the parameters of the existing stress-strain model with the best prediction. This new proposed model can satisfactorily describe the stress-strain behaviors for both geopolymeric natural aggregate concrete and geopolymeric recycled aggregate concrete.
Tang, Z, Li, W, Hu, Y, Zhou, JL & Tam, VWY 2019, 'Review on designs and properties of multifunctional alkali-activated materials (AAMs)', Construction and Building Materials, vol. 200, pp. 474-489.
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© 2018 Elsevier Ltd The stream of research on alkali-activated materials (AAMs) has expanded rapidly during the last decades owing to the potential as a viable alternative to cement-based materials. In addition to the load-carrying function, AAMs have been integrated with other functions to develop advanced construction materials, namely multifunctional AAMs. Multifunctional AAMs are intelligent systems not only serve a basic structural function but also exhibit other functional properties or have the abilities to react upon external stimuli or disturbances. Materials of this kind have tremendous potential to enhance the mechanical performance and durability of structure, improve the reliability and longevity of infrastructure, as well as reduce life-cycle service and maintenance cost. These multifunctional properties are mainly achieved through materials composition design, incorporation of functional elements, or microstructure modification. This paper presents an overview on designs and properties of multifunctional AAMs covering the smart functions, mechanical functions, and electrical functions, and with special attention to their definition, principles, and current progress. Furthermore, the challenges in the research of multifunctional AAMs have been discussed, as well as the future directions to increase the innovation and engineering application of these materials and structures.
Tang, Z, Li, W, Ke, G, Zhou, JL & Tam, VWY 2019, 'Sulfate attack resistance of sustainable concrete incorporating various industrial solid wastes', Journal of Cleaner Production, vol. 218, pp. 810-822.
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© 2019 Elsevier Ltd Industrial solid wastes are inducing severe environmental problems, but the problem can be overcame by reusing them as construction materials. The sulfate resistances of sustainable concrete incorporating various solid waste materials, including waste glass powder (WGP), coal gangue powder (CGP) and fly ash (FA) were investigated in this study. Concrete mixes with different water to binder (w/b) ratios and containing various solid waste materials as partial replacement of Portland cement by ratios of 10%, 20%, and 30% were prepared. These mixes were immersed in the 5% Na 2 SO 4 solution for a total period of 22 months. The sulfate attack resistances were evaluated extensively based on visual appearance, mass change, compressive strength, splitting tensile strength, ultrasonic pulse velocity, mineralogy, and microstructure. The results indicate that regardless of the type and content of solid waste materials, the replacement of cement by solid waste materials exhibit a positive impact on the sulfate attack resistance. Under the same substitution level, WGP appear to be the most effective in offsetting the destructive effect of sulfate attack, followed by CGP and FA. Therefore, sustainable concrete incorporating solid waste materials can not only promote the recycling of solid waste, but also provide high sulfate attack resistance.
Tang, Z, Shan, B, Li, WG, Peng, Q & Xiao, Y 2019, 'Structural behavior of glubam I-joists', Construction and Building Materials, vol. 224, pp. 292-305.
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© 2019 Elsevier Ltd Glubam, a new type of engineered bamboo composites, is a promising structural material characterized by outstanding mechanical performance and environmental friendliness. In this study, glubam I-joists, with the spans ranging from 2.4 m to 7.5 m, were prepared and tested to evaluate their structural behavior. The glubam I-joists were lengthened by finger joints, and two kinds of connections were used to connect the web and flanges. Four-point bending tests were conducted to examine the failure modes, load-deflection relationships and load carrying capacity of glubam I-joists. Test results indicated that the dominant failure modes of glubam I-joists included shear failure at the finger joint in the web, bending failure at the finger joint in the bottom flange and lateral buckling. Correspondingly, the load carrying capacity of glubam I-joists was governed by the bending strength, shear capacity and critical bending moment. Glubam I-joists have relatively higher mechanical performance compared with other engineered bamboo or timber I-joists with similar dimension, and the bending capacity of the glubam I-joist with continuous web-to-flange connection meets the requirement specified in Chinese code. Based on the experimental findings and existing methods, theoretical methods were proposed for predicting the stiffness and load carrying capacity of glubam I-joist and were also validated by the test results.
Tao, M, Li, Z, Cao, W, Li, X & Wu, C 2019, 'Stress redistribution of dynamic loading incident with arbitrary waveform through a circular cavity', International Journal for Numerical and Analytical Methods in Geomechanics, vol. 43, no. 6, pp. 1279-1299.
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SummaryIn actual geotechnical and civil engineering, dynamic stress concentrations around cavities generated by wave sources widely exist. In this study, based on the complex variable theory and Fourier transform method, the expression of the dynamic stress concentration factor (DSCF) around a circular cavity in infinite homogeneous media subjected to transient waves with arbitrary waveform is obtained. The relationships between both steady‐state and transient DSCF and their waveform parameters are investigated quantitatively. The results indicate that a relatively large tensile stress is generated with low Poisson's ratio under steady‐state incidence. Under the condition of transient incidence, the position of the wave peak has a minor effect on the DSCF in the case of small wavenumber, but it has a significant effect in the opposite case. It is found that when the wavenumber is high, such as 0.5, the stress response lags behind the stress wave. In addition, the closer the wave peak to the center of the waveform, the greater the potential damage of the transient incidence.
Tehrani, K, Zhang, Y, Scheuermann, A & Williams, DJ 2019, 'Comparison of air entry values from soil water retention and volumetric shrinkage characteristic curves', Japanese Geotechnical Society Special Publication, vol. 7, no. 2, pp. 340-343.
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Teng, J, Zhang, X, Zhang, S, Zhao, C & Sheng, D 2019, 'An analytical model for evaporation from unsaturated soil', Computers and Geotechnics, vol. 108, pp. 107-116.
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© 2018 Evaporation from unsaturated soil is characterized by vapor transfer in the upper part and liquid water transfer in the lower part of the soil. This study develops an analytical model for identifying the vaporization plane where the evaporation occurs, and the model consists of three partial differential equations that respectively govern the vapor flow, liquid water flow and heat transfer. These equations are solved simultaneously for the transient water content profile, evaporation rate, transient temperature profile and location of the vaporization plane. A series of experiments are used to validate the proposed analytical model, which indicates that this model can reasonably well predict the temporal water content profile and evaporation rate during the evaporation process. The result shows that the evaporation rate during falling rate stage is proportional to the inverse of the square root of elapsed time, and the proportionality is affected by the vapor diffusion coefficient, heat diffusion coefficient, and critical water content. The depth of vaporization plane is found to be independent of soil hydraulic properties, but only dependent on the heat diffusion coefficient of the soil. It is also revealed that heat diffusion coefficient has a pronounced influence on the evaporation process, which has not been observed in previous studies. A larger thermal diffusion coefficient leads to a faster advancing and a deeper vaporization plane, as well as a faster decreasing evaporation rate. The analytical model provides a useful tool for investigating the mechanism of the evaporation process.
Teoh, YH, How, HG, Masjuki, HH, Nguyen, H-T, Kalam, MA & Alabdulkarem, A 2019, 'Investigation on particulate emissions and combustion characteristics of a common-rail diesel engine fueled with Moringa oleifera biodiesel-diesel blends', Renewable Energy, vol. 136, pp. 521-534.
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Terechovs, AKE, Ansari, AJ, McDonald, JA, Khan, SJ, Hai, FI, Knott, NA, Zhou, J & Nghiem, LD 2019, 'Occurrence and bioconcentration of micropollutants in Silver Perch (Bidyanus bidyanus) in a reclaimed water reservoir', Science of The Total Environment, vol. 650, no. Pt 1, pp. 585-593.
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© 2018 This study examined the occurrence of 49 micropollutants in reclaimed water and Silver Perch (Bidyanus bidyanus) living in a reclaimed water reservoir. The numbers of micropollutants detected in reclaimed water, Silver Perch liver, and Silver Perch flesh were 20, 23, and 19, respectively. Concentrations of all micropollutants in reclaimed water, except benzotriazole, were well below the Australian Guideline for Recycled Water (AGRW) values for potable purposes. The concentration of benzotriazole in reclaimed water was 675 ± 130 ng/L while the AGRW value for this compound was 7 ng/L. Not all micropollutants detected in the water phase were identified in the Silver Perch flesh and liver tissues. Likewise, not all micropollutants detected in the Silver Perch flesh and liver were identified in the reclaimed water. In general, micropollutant concentrations in the liver were higher than in the flesh. Perfluorooctane sulfonate (PFOS) was detected at a trace level in reclaimed water well below the AGRW guideline value for potable purposes, but showed a high and medium bioconcentration factor in Silver Perch liver and flesh, respectively. In addition, the risk quotient for PFOS was medium and high when considering its concentration in Silver Perch liver and flesh, respectively. Results reported here highlight the need to evaluate multiple parameters for a comprehensive risk assessment. The results also single out PFOS as a notable contaminant of concern for further investigation.
Thabit, MS, Hawari, AH, Ammar, MH, Zaidi, S, Zaragoza, G & Altaee, A 2019, 'Evaluation of forward osmosis as a pretreatment process for multi stage flash seawater desalination', Desalination, vol. 461, pp. 22-29.
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© 2019 The present study evaluates the feasibility of applying forward osmosis (FO) process for the pretreatment of feed solution to a Multi Stage Flash (MSF) desalination plant. For the first time, real brine reject and real seawater were used as the draw solution and the feed solution, respectively in the FO process. The FO pretreatment is expected to dilute the brine reject and reduce the concentration of divalent ions, which are responsible for scale formation on the surface of heat exchanger in the MSF evaporator unit. The FO experiments were performed at different draw solution temperatures ranging between 25 and 40 °C, different draw and feed solutions flowrates and different membrane orientations. A maximum average membrane flux of 22.3 L/m2·h was reported at a draw solution temperature of 40 °C and 0.8 and 2.0 LPM flow rate of draw and feed solutions, respectively. The experimental results also revealed the process sensitivity to the feed solution temperature. It was found that the average membrane flux in the FO process operating at 0.8 and 2 LPM draw and feed solution flow rates, respectively was 16.9 L/m2·h at 25 °C brine temperature but increased to 22.3 L/m2·h at 40 °C brine temperature. These membrane fluxes resulted in 3% and 8.5% dilution of the draw solution at 25 °C and 40 °C temperatures, respectively. The average membrane flux in the FO mode was equal to that in the PRO mode at low flow rates but it was lower than that in the PRO mode at high flow rates of the feed and draw solutions. The outcomes of the study are very promising with regard to membrane flux and dilution of draw solution.
Thanh, HT, Li, J & Zhang, YX 2019, 'Numerical modelling of the flow of self-consolidating engineered cementitious composites using smoothed particle hydrodynamics', Construction and Building Materials, vol. 211, pp. 109-119.
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Thomas, P, Aldrige, L & Smallwood, A 2019, 'Water in opal – what can it tell us?', InColor Magazine, no. 41, pp. 62-69.
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Opal is a hydrous silica composed of predominantly silicon dioxide and water. The chemical composition of opal is normally described by the general formula SiO2.nH2O. The formula indicates that opal contains water and the value of ‘n’ is variable so the water content is variable and is known to range widely. Such a simple formula hides much of the important characteristics of how water is contained in opal and the variability in the water content and states of water is intricately involved in the formation of opal and may influence properties of the opal as a gemstone. The understanding of the states of water in opal is therefore of importance. The way in which the water is contained provides clues to the mechanisms of formation of opal. The water contained may also be used as a probe to help elucidate the complex microstructure beyond the sphere array structure in which precious opal, in particular, is described. This article will outline the types of water present in opal that displays play-of colour (POC) and how these types have been determined using chemical and physical laboratory characterisation techniques.
Thöns, S & Stewart, MG 2019, 'On decision optimality of terrorism risk mitigation measures for iconic bridges', Reliability Engineering & System Safety, vol. 188, pp. 574-583.
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This paper describes the assessment of the cost efficiency of risk mitigation strategies for terrorist attacks with Improvised Explosive Devices (IEDs) for an iconic bridge structure. The assessment is performed with a decision theoretical framework building upon very recent advances in the COST Action TU1402 on Quantifying the Value of Structural Heath Monitoring. The decision scenario is formulated for a decision maker constituting an authority responsible for the societal safety of the infrastructure and consequently the direct risks for the infrastructure owner and the indirect risk due to fatalities and importance of the infrastructure are considered. The mitigation strategies are classified within the decision theoretical context as prior analyses for the assessment of protection strategies and as control strategies requiring a pre-posterior decision analysis. The identification of efficient risk mitigation strategies is based (1) on the risk and expected cost based optimization of actions and information and their combination before implementation, (2) on quantifying and ensuring the significance in risk and expected cost reduction and (3) on quantifying and ensuring a high probability of cost efficiency. These criteria, i.e. the optimality, significance and efficiency ensure the performance of the strategies at the decision point in time before implementation. It is found that the strategies are relying on the identification of the threat level and that control strategies are in favor as their significance and probability of efficiency are higher and their costs are adjustable. However, for high threat levels, both the bridge protection strategies and control strategies are cost efficient.
Tien Bui, D, Khosravi, K, Shahabi, H, Daggupati, P, Adamowski, JF, M.Melesse, A, Thai Pham, B, Pourghasemi, HR, Mahmoudi, M, Bahrami, S, Pradhan, B, Shirzadi, A, Chapi, K & Lee, S 2019, 'Flood Spatial Modeling in Northern Iran Using Remote Sensing and GIS: A Comparison between Evidential Belief Functions and Its Ensemble with a Multivariate Logistic Regression Model', Remote Sensing, vol. 11, no. 13, pp. 1589-1589.
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Floods are some of the most dangerous and most frequent natural disasters occurring in the northern region of Iran. Flooding in this area frequently leads to major urban, financial, anthropogenic, and environmental impacts. Therefore, the development of flood susceptibility maps used to identify flood zones in the catchment is necessary for improved flood management and decision making. The main objective of this study was to evaluate the performance of an Evidential Belief Function (EBF) model, both as an individual model and in combination with Logistic Regression (LR) methods, in preparing flood susceptibility maps for the Haraz Catchment in the Mazandaran Province, Iran. The spatial database created consisted of a flood inventory, altitude, slope angle, plan curvature, Topographic Wetness Index (TWI), Stream Power Index (SPI), distance from river, rainfall, geology, land use, and Normalized Difference Vegetation Index (NDVI) for the region. After obtaining the required information from various sources, 151 of 211 recorded flooding points were used for model training and preparation of the flood susceptibility maps. For validation, the results of the models were compared to the 60 remaining flooding points. The Receiver Operating Characteristic (ROC) curve was drawn, and the Area Under the Curve (AUC) was calculated to obtain the accuracy of the flood susceptibility maps prepared through success rates (using training data) and prediction rates (using validation data). The AUC results indicated that the EBF, EBF from LR, EBF-LR (enter), and EBF-LR (stepwise) success rates were 94.61%, 67.94%, 86.45%, and 56.31%, respectively, and the prediction rates were 94.55%, 66.41%, 83.19%, and 52.98%, respectively. The results showed that the EBF model had the highest accuracy in predicting flood susceptibility within the catchment, in which 15% of the total areas were located in high and very high susceptibility classes, and 62% were located in low and ...
Tien Bui, D, Shahabi, H, Omidvar, E, Shirzadi, A, Geertsema, M, Clague, J, Khosravi, K, Pradhan, B, Pham, B, Chapi, K, Barati, Z, Bin Ahmad, B, Rahmani, H, Gróf, G & Lee, S 2019, 'Shallow Landslide Prediction Using a Novel Hybrid Functional Machine Learning Algorithm', Remote Sensing, vol. 11, no. 8, pp. 931-931.
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We used a novel hybrid functional machine learning algorithm to predict the spatial distribution of landslides in the Sarkhoon watershed, Iran. We developed a new ensemble model which is a combination of a functional algorithm, stochastic gradient descent (SGD) and an AdaBoost (AB) Meta classifier namely ABSGD model to predict the landslides. The model incorporates 20 landslide conditioning factors, which we ranked using the least-square support vector machine (LSSVM) technique. For the modeling, we considered 98 landslide locations, of which 70% (79) were used for training and 30% (19) for validation processes. Model validation was performed using sensitivity, specificity, accuracy, the root mean square error (RMSE) and the area under the receiver operatic characteristic (AUC) curve. We also used soft computing benchmark models, including SGD, logistic regression (LR), logistic model tree (LMT) and functional tree (FT) algorithms for model validation and comparison. The selected conditioning factors were significant in landslide occurrence but distance to road was found to be the most important factor. The ABSGD model (AUC= 0.860) outperformed the LR (0.797), SGD (0.776), LMT (0.740) and FT (0.734) models. Our results confirm that the combined use of a functional algorithm and a Meta classifier prevents over-fitting, reduces noise and enhances the power prediction of the individual SGD algorithm for the spatial prediction of landslides.
Tien Bui, D, Shirzadi, A, Chapi, K, Shahabi, H, Pradhan, B, Pham, B, Singh, V, Chen, W, Khosravi, K, Bin Ahmad, B & Lee, S 2019, 'A Hybrid Computational Intelligence Approach to Groundwater Spring Potential Mapping', Water, vol. 11, no. 10, pp. 2013-2013.
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This study proposes a hybrid computational intelligence model that is a combination of alternating decision tree (ADTree) classifier and AdaBoost (AB) ensemble, namely “AB–ADTree”, for groundwater spring potential mapping (GSPM) at the Chilgazi watershed in the Kurdistan province, Iran. Although ADTree and its ensembles have been widely used for environmental and ecological modeling, they have rarely been applied to GSPM. To that end, a groundwater spring inventory map and thirteen conditioning factors tested by the chi-square attribute evaluation (CSAE) technique were used to generate training and testing datasets for constructing and validating the proposed model. The performance of the proposed model was evaluated using statistical-index-based measures, such as positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity accuracy, root mean square error (RMSE), and the area under the receiver operating characteristic (ROC) curve (AUROC). The proposed hybrid model was also compared with five state-of-the-art benchmark soft computing models, including single ADTree, support vector machine (SVM), stochastic gradient descent (SGD), logistic model tree (LMT), logistic regression (LR), and random forest (RF). Results indicate that the proposed hybrid model significantly improved the predictive capability of the ADTree-based classifier (AUROC = 0.789). In addition, it was found that the hybrid model, AB–ADTree, (AUROC = 0.815), had the highest goodness-of-fit and prediction accuracy, followed by the LMT (AUROC = 0.803), RF (AUC = 0.803), SGD, and SVM (AUROC = 0.790) models. Indeed, this model is a powerful and robust technique for mapping of groundwater spring potential in the study area. Therefore, the proposed model is a promising tool to help planners, decision makers, managers, and governments in the management and planning of groundwater resources.
Tien Bui, D, Shirzadi, A, Shahabi, H, Chapi, K, Omidavr, E, Pham, BT, Talebpour Asl, D, Khaledian, H, Pradhan, B, Panahi, M, Bin Ahmad, B, Rahmani, H, Gróf, G & Lee, S 2019, 'A Novel Ensemble Artificial Intelligence Approach for Gully Erosion Mapping in a Semi-Arid Watershed (Iran)', Sensors, vol. 19, no. 11, pp. 2444-2444.
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In this study, we introduced a novel hybrid artificial intelligence approach of rotation forest (RF) as a Meta/ensemble classifier based on alternating decision tree (ADTree) as a base classifier called RF-ADTree in order to spatially predict gully erosion at Klocheh watershed of Kurdistan province, Iran. A total of 915 gully erosion locations along with 22 gully conditioning factors were used to construct a database. Some soft computing benchmark models (SCBM) including the ADTree, the Support Vector Machine by two kernel functions such as Polynomial and Radial Base Function (SVM-Polynomial and SVM-RBF), the Logistic Regression (LR), and the Naïve Bayes Multinomial Updatable (NBMU) models were used for comparison of the designed model. Results indicated that 19 conditioning factors were effective among which distance to river, geomorphology, land use, hydrological group, lithology and slope angle were the most remarkable factors for gully modeling process. Additionally, results of modeling concluded the RF-ADTree ensemble model could significantly improve (area under the curve (AUC) = 0.906) the prediction accuracy of the ADTree model (AUC = 0.882). The new proposed model had also the highest performance (AUC = 0.913) in comparison to the SVM-Polynomial model (AUC = 0.879), the SVM-RBF model (AUC = 0.867), the LR model (AUC = 0.75), the ADTree model (AUC = 0.861) and the NBMU model (AUC = 0.811).
To, VHP, Nguyen, TV, Bustamante, H & Vigneswaran, S 2019, 'Deleterious effects of soluble extracellular polymeric substances on polyacrylamide demand for conditioning of anaerobically digested sludge', Journal of Environmental Chemical Engineering, vol. 7, no. 2, pp. 102941-102941.
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© 2019 Elsevier Ltd. All rights reserved. High polyacrylamide (polymer) demand for conditioning of sludge, especially anaerobically digested sludge (ADS), is a major issue for the water industry. Currently, this problem is being investigated and the reasons for doing so are varied. It has been demonstrated that excess amounts of soluble extracellular polymeric substances (EPS) can lead to high polymer demand for conditioning. This study developed a simple and unique yet effective method for quantifying the contribution of soluble EPS to conditioning polymer demand. It did this by measuring absorbance at 191.5 nm wavelength of the supernatant derived from conditioned ADS. Experimental results confirmed that approximately 87 wt% of soluble EPS interacted with polyacrylamides during the conditioning process. Furthermore, they revealed that a specified amount of soluble EPS could not be removed by polymer flocculation despite high polymer dosage. This study concluded that about 86 wt% of the polyacrylamide used for conditioning was consumed solely by soluble EPS. These results confirm the important role of reducing this EPS fraction in ADS in order to curtail significant chemical costs for sludge conditioning and dewatering.
Tran, HN, Nguyen, DT, Le, GT, Tomul, F, Lima, EC, Woo, SH, Sarmah, AK, Nguyen, HQ, Nguyen, PT, Nguyen, DD, Nguyen, TV, Vigneswaran, S, Vo, D-VN & Chao, H-P 2019, 'Adsorption mechanism of hexavalent chromium onto layered double hydroxides-based adsorbents: A systematic in-depth review', Journal of Hazardous Materials, vol. 373, pp. 258-270.
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© 2019 Elsevier B.V. An attempt has been made in this review to provide some insights into the possible adsorption mechanisms of hexavalent chromium onto layered double hydroxides-based adsorbents by critically examining the past and present literature. Layered double hydroxides (LDH) nanomaterials are typical dual-electronic adsorbents because they exhibit positively charged external surfaces and abundant interlayer anions. A high positive zeta potential value indicates that LDH has a high affinity to Cr(VI) anions in solution through electrostatic attraction. The host interlayer anions (i.e., Cl−, NO3−, SO42−, and CO32−) provide a high anion exchange capacity (53–520 meq/100 g) which is expected to have an excellent exchangeable capacity to Cr(VI) oxyanions in water. Regarding the adsorption-coupled reduction mechanism, when Cr(VI) anions make contact with the electron-donor groups in the LDH, they are partly reduced to Cr(III) cations. The reduced Cr(III) cations are then adsorbed by LDH via numerous interactions, such as isomorphic substitution and complexation. Nonetheless, the adsorption-coupled reduction mechanism is greatly dependent on: (1) the nature of divalent and trivalent salts utilized in LDH preparation, and the types of interlayer anions (i.e., guest intercalated organic anions), and (3) the adsorption experiment conditions. The low Brunauer–Emmett–Teller specific surface area of LDH (1.80–179 m2/g) suggests that pore filling played an insignificant role in Cr(VI) adsorption. The Langmuir maximum adsorption capacity of LDH (Qomax) toward Cr(VI) was significantly affected by the natures of used inorganic salts and synthetic methods of LDH. The Qomax values range from 16.3 mg/g to 726 mg/g. Almost all adsorption processes of Cr(VI) by LDH-based adsorbent occur spontaneously (ΔG° <0) and endothermically (ΔH° >0) and increase the randomness (ΔS° >0) in the system. Thus, LDH has much potential as a promising material that can effectively rem...
Tran, HN, Nguyen, HC, Woo, SH, Nguyen, TV, Vigneswaran, S, Hosseini-Bandegharaei, A, Rinklebe, J, Kumar Sarmah, A, Ivanets, A, Dotto, GL, Bui, TT, Juang, R-S & Chao, H-P 2019, 'Removal of various contaminants from water by renewable lignocellulose-derived biosorbents: a comprehensive and critical review', Critical Reviews in Environmental Science and Technology, vol. 49, no. 23, pp. 2155-2219.
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© 2019, © 2019 Taylor & Francis Group, LLC. Contaminants in water bodies cause potential health risks for humans and great environmental threats. Therefore, the development and exploration of low-cost, promising adsorbents to remove contaminants from water resources as a sustainable option is one focus of the scientific community. Here, we conducted a critical review regarding the application of pristine and modified/treated biosorbents derived from leaves for the removal of various contaminants. These include potentially toxic cationic and oxyanionic metal ions, radioactive metal ions, rare earth elements, organic cationic and anionic dyes, phosphate, ammonium, and fluoride from water media. Similar to lignocellulose-based biosorbents, leaf-based biosorbents exhibit a low specific surface area and total pore volume but have abundant surface functional groups, high concentrations of light metals, and a high net surface charge density. The maximum adsorption capacity of biosorbents strongly depends on the operation conditions, experiment types, and adsorbate nature. The absorption mechanism of contaminants onto biosorbents is complex; therefore, typical experiments used to identify the primary mechanism of the adsorption of contaminants onto biosorbents were thoroughly discussed. It was concluded that byproduct leaves are renewable, biodegradable, and promising biosorbents which have the potential to be used as a low-cost green alternative to commercial activated carbon for effective removal of various contaminants from the water environment in the real-scale plants.
Tran, NH, Hoang, L, Nghiem, LD, Nguyen, NMH, Ngo, HH, Guo, W, Trinh, QT, Mai, NH, Chen, H, Nguyen, DD, Ta, TT & Gin, KY-H 2019, 'Occurrence and risk assessment of multiple classes of antibiotics in urban canals and lakes in Hanoi, Vietnam', Science of The Total Environment, vol. 692, pp. 157-174.
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Tran, VH, Lim, S, Han, DS, Pathak, N, Akther, N, Phuntsho, S, Park, H & Shon, HK 2019, 'Efficient fouling control using outer-selective hollow fiber thin-film composite membranes for osmotic membrane bioreactor applications', Bioresource Technology, vol. 282, pp. 9-17.
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© 2019 Elsevier Ltd This paper investigates the efficiency of fouling mitigation methods using a novel outer selective hollow fiber thin-film composite forward osmosis (OSHF TFC FO) membrane for osmosis membrane bioreactor (OMBR) system treating municipal wastewater. Two home-made membrane modules having similar transport properties were used. Two operation regimes with three different fouling mitigation strategies were utilized to test the easiness of membrane for fouling cleaning. These two membrane modules demonstrated high performance with high initial water flux of 14.4 LMH and 14.1 LMH and slow increase rate of mixed liquor's salinity in the bioreactor using 30 g/L NaCl as draw solution. OMBR system showed high removals of total organic carbon and NH4 + -N (>98%). High fouling cleaning efficiency was achieved using OSHF TFC FO membrane with different fouling control methods. These results showed that this membrane is suitable for OMBR applications due to its high performance and its simplicity for fouling mitigation.
Tu, R, Jin, W, Han, S-F, Zhou, X, Wang, T, Gao, S-H, Wang, Q, Chen, C, Xie, G-J & Wang, Q 2019, 'Rapid enrichment and ammonia oxidation performance of ammonia-oxidizing archaea from an urban polluted river of China', Environmental Pollution, vol. 255, no. Pt 2, pp. 113258-113258.
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© 2019 Elsevier Ltd In this study, the optimum growth conditions of AOA in a polluted river were investigated. AOB also play an important role in ammonia oxidation in the river water.
Turner, BD, Sloan, SW & Currell, GR 2019, 'Novel remediation of per- and polyfluoroalkyl substances (PFASs) from contaminated groundwater using Cannabis Sativa L. (hemp) protein powder', Chemosphere, vol. 229, pp. 22-31.
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Ubando, AT, Chen, W-H & Ong, HC 2019, 'Iron oxide reduction by graphite and torrefied biomass analyzed by TG-FTIR for mitigating CO2 emissions', Energy, vol. 180, pp. 968-977.
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Uddin, MN, Rahman, MA, Mofijur, M, Taweekun, J, Techato, K & Rasul, MG 2019, 'Renewable energy in Bangladesh: Status and prospects', Energy Procedia, vol. 160, pp. 655-661.
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© 2019 The Authors. Published by Elsevier Ltd. Global energy demand has risen sharply over the years with developing countries recording the greatest share in this trend. Biomass as an energy resource is mostly available locally and can easily be converted into secondary energy without huge capital investments. Nowadays, Bangladesh shares a percentage of renewable energy only 3% of total energy ratio, Bangladesh has already taken a master plan in the renewable energy sector. Whereas installed electricity generation installed capacity of Bangladesh rapidly increased to 13265 MW with captive generation capacity which is insufficient for fulfilling the demand of electricity of the nations. One-third of the power production of Bangladesh depends on expensive imported fossil fuel energy resources and 65% of power generation depends on a natural gas reserve of the country, though one day the reserve of current gas will be diminished. Moreover, inadequate electricity production leads the country in a un-industrialization. The present and future crucial energy crisis situation adapted by installing renewable power into electricity production. The current renewable energy agenda of Bangladeshi government force the specialization of renewable energy generation budget by decreasing global pollution with saving movement of biomass, solar, hydro, wind, and tidal power sector. This paper presents the currents national energy scenario of Bangladesh. According to this, the greater potentiality of renewable energy resources is also reviewed and presented in this paper.
Vahedian, A, Shrestha, R & Crews, K 2019, 'Experimental and analytical investigation on CFRP strengthened glulam laminated timber beams: Full-scale experiments', Composites Part B: Engineering, vol. 164, pp. 377-389.
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Vakhshouri, B & Nejadi, S 2019, 'Empirical models and design codes in prediction of modulus of elasticity of concrete', Frontiers of Structural and Civil Engineering, vol. 13, no. 1, pp. 38-48.
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© 2018, Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature. Modulus of Elasticity (MOE) is a key parameter in reinforced concrete design. It represents the stress-strain relationship in the elastic range and is used in the prediction of concrete structures. Out of range estimation of MOE in the existing codes of practice strongly affect the design and performance of the concrete structures. This study includes: (a) evaluation and comparison of the existing analytical models to estimating the MOE in normal strength concrete, and (b) proposing and verifying a new model. In addition, a wide range of experimental databases and empirical models to estimate the MOE from compressive strength and density of concrete are evaluated to verification of the proposed model. The results show underestimation of MOE of conventional concrete in majority of the existing models. Also, considering the consistency between density and mechanical properties of concrete, the predicted MOE in the models including density effect, are more compatible with the experimental results.
Vakhshouri, B, Rasiah, SR & Nejadi, S 2019, 'Analytical study of the drying shrinkage in light-weight concrete containing EPS beads', Advances in Cement Research, vol. 31, no. 7, pp. 308-318.
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This study investigates the drying shrinkage of light-weight concrete containing expanded polystyrene beads. Nine shrinkage specimens in three groups were subjected to three different conditions of drying and wetting periods for 450 d. The effect of the weight loss of specimens on the shrinkage is studied. A proposed new relationship to predict the shrinkage behaviour of the specimens is verified by the existing models. A bilinear relationship between the rate of weight loss and shrinkage increment is also developed. Results show that a longer curing period strongly affects the shrinkage behaviour over the first few months. The rate of weight loss, rate of shrinkage with time and the ratio of the rate of weight loss to the initial weight of specimens are also investigated.
Van, HT, Nguyen, LH, Nguyen, VD, Nguyen, XH, Nguyen, TH, Nguyen, TV, Vigneswaran, S, Rinklebe, J & Tran, HN 2019, 'Characteristics and mechanisms of cadmium adsorption onto biogenic aragonite shells-derived biosorbent: Batch and column studies', Journal of Environmental Management, vol. 241, pp. 535-548.
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© 2018 Elsevier Ltd Calcium carbonate (CaCO3)-enriched biomaterial derived from freshwater mussel shells (FMS) was used as a non-porous biosorbent to explore the characteristics and mechanisms of cadmium adsorption in aqueous solution. The adsorption mechanism was proposed by comparing the FMS properties before and after adsorption alongside various adsorption studies. The FMS biosorbent was characterized using nitrogen adsorption/desorption isotherm, X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, Fourier-transform infrared spectroscopy, and point of zero charge. The results of batch experiments indicated that FMS possessed an excellent affinity to Cd(II) ions within solutions pH higher than 4.0. An increase in ionic strength resulted in a significant decrease in the amount of Cd(II) adsorbed onto FMS. Kinetic study demonstrated that the adsorption process quickly reached equilibrium at approximately 60 min. The FMS biosorbent exhibited the Langmuir maximum adsorption capacity as follows: 18.2 mg/g at 10 °C < 26.0 mg/g at 30 °C < 28.6 mg/g at 50 °C. The Cd(II) adsorption process was irreversible, spontaneous (−ΔG°), endothermic (+ΔH°), and more random (+ΔS°). Selective order (mmol/g) of metal cations followed as Pb2+ > Cd2+ > Cu2+ > Cr3+ > Zn2+. For column experiments, the highest Thomas adsorption capacity (7.86 mg/g) was achieved at a flow rate (9 mL/min), initial Cd(II) concentration (10 mg/L), and bed height (5 cm). The Cd(II) removal by FMS was regarded as non-activated chemisorption that occurred very rapidly (even at a low temperature) with a low magnitude of activation energy. Primary adsorption mechanism was surface precipitation. Cadmium precipitated in the primary (Cd,Ca)CO3 form with a calcite-type structure on the FMS surface. A crust of rhombohedral crystals on the substrate was observed by SEM. Freshwater mussel shells have the potential as a renewable adsorbent to remove cadmium from water.
Vo, HNP, Ngo, HH, Guo, W, Liu, Y, Chang, SW, Nguyen, DD, Nguyen, PD, Bui, XT & Ren, J 2019, 'Identification of the pollutants’ removal and mechanism by microalgae in saline wastewater', Bioresource Technology, vol. 275, pp. 44-52.
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© 2018 Elsevier Ltd This study investigated the growth dynamics of a freshwater and marine microalgae with supported biochemical performance in saline wastewater, the pollutants assimilation by a developed method, and the mechanism of salinity's effect to pollutants assimilation. Maximal biomass yield was 400–500 mg/L at 0.1–1% salinity while the TOC, NO3−-N, PO43−-P were eliminated 39.5–92.1%, 23–97.4% and 7–30.6%, respectively. The biomass yield and pollutants removal efficiencies reduced significantly when salinity rose from 0.1 to 5%. The freshwater Chlorella vulgaris performed its best with a focus on TOC removal at 0.1% salinity. The marine Chlorella sp. was prominent for removing NO3−-N at 0.1–1% salinity. Through the developed method, the freshwater C. vulgaris competed to the marine microalgae referring to pollutants assimilation up to 5% salinity. This study unveiled the mechanism of salinity's effect with evidence of salt layer formation and salt accumulation in microalgae.
Vo, HNP, Ngo, HH, Guo, W, Nguyen, TMH, Liu, Y, Liu, Y, Nguyen, DD & Chang, SW 2019, 'A critical review on designs and applications of microalgae-based photobioreactors for pollutants treatment', Science of The Total Environment, vol. 651, no. Pt 1, pp. 1549-1568.
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© 2018 Elsevier B.V. The development of the photobioreactors (PBs) is recently noticeable as cutting-edge technology while the correlation of PBs' engineered elements such as modellings, configurations, biomass yields, operating conditions and pollutants removal efficiency still remains complex and unclear. A systematic understanding of PBs is therefore essential. This critical review study is to: (1) describe the modelling approaches and differentiate the outcomes; (2) review and update the novel technical issues of PBs' types; (3) study microalgae growth and control determined by PBs types with comparison made; (4) progress and compare the efficiencies of contaminants removal given by PBs' types and (5) identify the future perspectives of PBs. It is found that Monod model's shortcoming in internal substrate utilization is well fixed by modified Droop model. The corroborated data also remarks an array of PBs' types consisting of flat plate, column, tubular, soft-frame and hybrid configuration in which soft-frame and hybrid are the latest versions with higher flexibility, performance and smaller foot-print. Flat plate PBs is observed with biomass yield being 5 to 20 times higher than other PBs types while soft-frame and membrane PBs can also remove pharmaceutical and personal care products (PPCPs) up to 100%. Looking at an opportunity for PBs in sustainable development, the flat plate PBs are applicable in PB-based architectures and infrastructures indicating an encouraging revenue-raising potential.
Vo, T-D-H, Bui, X-T, Lin, C, Nguyen, V-T, Hoang, T-K-D, Nguyen, H-H, Nguyen, P-D, Ngo, HH & Guo, W 2019, 'A mini-review on shallow-bed constructed wetlands: a promising innovative green roof', Current Opinion in Environmental Science & Health, vol. 12, pp. 38-47.
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© 2019 Elsevier B.V. Shallow-bed constructed wetland (SCW) has been used as a secondary wastewater treatment technology with low cost, less maintaining, and operational requirements and environmental friendliness. Green roof has been considered an effective solution in saving energy, enhancing green space, providing landscape aesthetics, limiting stormwater runoff causing flooding, and purifying air pollutants. Recently, a wetland roof (WR) has been interested as a good integration of these two technologies. To gain an insight understanding of this combination, this review aimed to provide the potential applications of SCW on the roof as a WR. Factors affecting performance, benefits, and challenges of SCW were also discussed. The literature data showed WR was a promising green technology that is needed to be investigated and scaled up in the future.
Volkova, L, Roxburgh, SH, Surawski, NC, Meyer, CPM & Weston, CJ 2019, 'Improving reporting of national greenhouse gas emissions from forest fires for emission reduction benefits: An example from Australia', Environmental Science & Policy, vol. 94, pp. 49-62.
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© 2018 Elsevier Ltd Forest fires are a significant contributor to global greenhouse gas (GHG) emissions. Accurate reporting of GHG emissions from forest fires requires development of detailed methodologies and country specific data for estimating emissions. In recent years, Australia has updated its national methodology for reporting GHG emissions from fires on temperate forested lands, using a Tier 2 approach of the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories. This involved refinement of the equation for estimating GHG emissions from fires provided in the Guidance, and the revision of country specific data which was derived from a comprehensive literature review. The refinements were key to transparent reporting and evaluation of the climatic impacts of mitigation actions such as forest fire management. In this paper we describe the steps required to develop a Tier 2 method in reporting fire emissions using this Australian example, the lessons learnt, and the steps required to reduce uncertainties in estimates. This paper may assist other countries seeking to estimate and report GHG emissions from forest fires by moving from the default Tier 1 method to Tier 2 using country-specific information.
Volpin, F, Chekli, L, Phuntsho, S, Ghaffour, N, Vrouwenvelder, JS & Shon, HK 2019, 'Optimisation of a forward osmosis and membrane distillation hybrid system for the treatment of source-separated urine', Separation and Purification Technology, vol. 212, pp. 368-375.
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© 2018 Elsevier B.V. The high concentration of nitrogen, phosphorous and potassium in human urine makes it a suitable raw material for fertiliser production. However, urine is often diluted with a significant amount of flushing water which increases the costs for the downstream nutrients recovery process. Re-using the water and the nutrients in the urine is paramount for enhancing the sustainability of our waste management system. In this work, a combination of forward osmosis (FO) and membrane distillation (MD) was used to extract distilled water from human urine. FO was chosen as MD pre-treatment to increase the overall nitrogen rejection and to prevent wetting of the MD membrane. The goal of this investigation was to tune the FO and MD operating parameters to reduce the nitrogen transport to the MD permeate. Urine pH, draw solution (DS) salt concentration and operating pressure were varied as a means to enhance the FO performances. On the other hand, feed temperature, nitrogen concentration and membrane characteristics were investigated to optimise the MD process. With 2.5 M NaCl as DS commercial FO membranes achieved a water flux between 31.5 and 28.7 L m−2 h−1 and a minimum nitrogen flux of 1.4 g L−1. An additional 33% reduction in the nitrogen transport was observed by applying minimal hydraulic pressure on the DS. However, this was also found to significantly reduce the net transmembrane water flux. Acidification of the feed was also beneficial for both FO and MD nitrogen rejection. Finally, we demonstrated that, by tuning the MD membrane porosity and thickness, higher MD permeate quality could be achieved. To conclude, the hybrid FO-MD process is expected to be an effective solution for the production of clean water and concentrated fertiliser from human urine. This double barrier separation process could be suitable for both water reclamation in space application and resource recovery in urban application.
Volpin, F, Heo, H, Hasan Johir, MA, Cho, J, Phuntsho, S & Shon, HK 2019, 'Techno-economic feasibility of recovering phosphorus, nitrogen and water from dilute human urine via forward osmosis', Water Research, vol. 150, pp. 47-55.
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© 2018 Elsevier Ltd Due to high phosphorus (P) and nitrogen (N) content, human urine has often proven to suitable raw material for fertiliser production. However, most of the urine diverting toilets or male urinals dilute the urine 2 to 10 times. This decreases the efficiency in the precipitation of P and stripping of N. In this work, a commercial fertiliser blend was used as forward osmosis (FO) draw solution (DS) to concentrate real diluted urine. During the concentration, the urea in the urine is recovered as it diffuses to the fertiliser. Additionally, the combination of concentrate PO43-, reverse Mg2+ flux from the DS and the Mg2+ presents in the flushing water, was able to recover the PO43- as struvite. With 50% concentrated urine, 93% P recovery was achieved without the addition of an external Mg2+. Concurrently, 50% of the N was recovered in the diluted fertiliser DS. An economic analysis was performed to understand the feasibility of this process. It was found that the revenue from the produced fertilisers could potentially offset the operational and capital costs of the system. Additionally, if the reduction in the downstream nutrients load is accounted for, the total revenue of the process would be over 5.3 times of the associated costs.
Volpin, F, Yu, H, Cho, J, Lee, C, Phuntsho, S, Ghaffour, N, Vrouwenvelder, JS & Shon, HK 2019, 'Human urine as a forward osmosis draw solution for the application of microalgae dewatering', Journal of Hazardous Materials, vol. 378, pp. 120724-120724.
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© 2019 Elsevier B.V. Human urine is a unique solution that has the right composition to constitute both a severe environmental threat and a rich source of nitrogen and phosphorous. In fact, between 4–9% of urine mass consists of ions, such as K+, Cl−, Na+ or NH4+. Because of its high ionic strength, urine osmotic pressure can reach values of up to 2000 kPa. With this in mind, this work aimed to study the effectiveness of real urine as a novel draw solution for forward osmosis. Water flux, reverse nitrogen flux and membrane fouling were investigated using fresh or hydrolysed urine. Water flux as high as 16.7 ± 1.1 L m−2 h−1 was recorded using real hydrolysed urine. Additionally, no support layer membrane fouling was noticed in over 20 h of experimentation. Urine was also employed to dewater a Chlorella vulgaris culture. A fourfold increase in algal concentration was achieved while having an average flux of 14.1 L m−2 h−1. During the algae dewatering, a flux decrease of about 19% was noticed; this was mainly due to a thin layer of algal deposition on the active side of the membrane. Overall, human urine was found to be an effective draw solution for forward osmosis.
Wang, B, Lau, Y-S, Huang, Y, Organ, B, Lee, S-C & Ho, K-F 2019, 'Investigation of factors affecting the gaseous and particulate matter emissions from diesel vehicles', Air Quality, Atmosphere & Health, vol. 12, no. 9, pp. 1113-1126.
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© 2019, Springer Nature B.V. This study presents a detailed investigation of diesel vehicle emissions utilizing chassis dynamometer testing. The recruited vehicle fleet consists of 15 in-use diesel vehicles, spanning a wide range of emission standards, engine sizes, weight, model year, etc. The real-time emission concentrations of nitrogen oxides (NOx), total hydrocarbons (THC), carbon monoxide (CO) and carbon dioxide (CO2), and the mass of particulate matter (PM) collected on filters are measured and used to calculate the vehicle emission factors (EFs) under various driving conditions. Results show that in general EFs of NOx, CO, THC, and PM of the recruited fleet span a wide range of values (NOx 0.80 ± 0.34 to 60.28 ± 2.94 g kg−1; THC 0.10 ± 0.04 to 5.28 ± 1.28 g kg−1; CO below detection limits to 24.01 ± 8.48 g kg−1; PM below detection limits to 2.47 ± 1.22 g kg−1). Further data analysis shows that the implementation of a higher emission standard has a significant effect on reducing the emission of pollutants, except for NOx. Driving conditions are also important factors affecting the EFs. Besides, statistical analysis shows a significant correlation between EFs of NOx with the testing weight and the maximum engine power of the vehicle. Further investigation is recommended to explore the effect of maintenance of the vehicles to the vehicular emission.
Wang, B, Ni, B-J, Yuan, Z & Guo, J 2019, 'Cometabolic biodegradation of cephalexin by enriched nitrifying sludge: Process characteristics, gene expression and product biotoxicity', Science of The Total Environment, vol. 672, pp. 275-282.
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© 2019 Elsevier B.V. The nitrifying systems have been reported to be able to biodegrade micropollutants, yet it is still unclear about the cometabolism of ammonia-oxidizing bacteria (AOB) towards micropollutants, in particular their enzyme and transcriptional responses under exposure of micropollutants. This study investigated cometabolic biodegradation of a selected antibiotic, cephalexin (CFX), by an enriched nitrifying culture through a series of batch experiments, together with the assessments of enzymatic activity, key gene expression, and biotoxicity of the degradation products. More than 99% CFX with an initial concentration of 50 μg/L could be removed with the presence of ammonium, while <44% of CFX removal was observed in the absence of ammonium, suggesting the cometabolic degradation of CFX by ammonia-oxidizing bacteria (AOB). After the addition of 50 μg/L CFX, the ammonia oxidizing rate (AOR) decreased from 36.6 to 11.0 mg N/(L·h·g VSS), followed by a slight recovery when CFX concentration decreased to below 8 μg/L. Ammonia monooxygenase (AMO) activity showed a similar trend with that of AOR. The quantitative reverse transcription PCR assay indicated that the expression level of amoA gene was significantly upregulated (up to 3-fold, p < 0.05) due to the addition of CFX, while decreased to the normal level once CFX was degraded, suggesting a mechanism of AOB to neutralize the toxicity of CFX by metabolizing ammonia more effectively. Meanwhile, the biotoxicity test showed the degradation products of CFX did not exhibit any antibacterial impacts in terms of cell viability, compared to the parent compounds. Our finding shed a light on AMO-mediated cometabolic biodegradation of antibiotics in nitrifying cultures.
Wang, B, Ni, B-J, Yuan, Z & Guo, J 2019, 'Insight into the nitrification kinetics and microbial response of an enriched nitrifying sludge in the biodegradation of sulfadiazine', Environmental Pollution, vol. 255, no. Pt 1, pp. 113160-113160.
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© 2019 Elsevier Ltd SDZ could be cometabolically degraded by enriched nitrifying culture, and the expression level of amoA gene was down-regulated during the process, but didn't decrease proportionally with AOR.
Wang, D, He, D, Liu, X, Xu, Q, Yang, Q, Li, X, Liu, Y, Wang, Q, Ni, B-J & Li, H 2019, 'The underlying mechanism of calcium peroxide pretreatment enhancing methane production from anaerobic digestion of waste activated sludge', Water Research, vol. 164, pp. 114934-114934.
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© 2019 Elsevier Ltd Recent investigations verified that calcium peroxide (CaO2) could be used to pretreat waste activated sludge to promote methane yield from anaerobic digestion. However, the underlying mechanism of how CaO2 pretreatment promotes methane production is unclear. This work therefore aims to provide insights into such systems. Experimental results showed that with an increase of CaO2 dosage from 0 to 0.14 g/g VSS (volatile suspended solids) the methane yield increased linearly from 146.3 to 215.9 mL/g VSS. Further increases of CaO2 resulted in decreases in methane yield. CaO2 pretreatment promoted the disintegration of sludge and the degradation of sludge recalcitrant organics (especially humus and lignocellulose), thereby providing more substrates for subsequent methane production. Ultraviolet absorption spectroscopy indicated that CaO2 enhanced the cleavage of unsaturated conjugated bonds and reduced the aromaticity of humus and lignocellulose. Fourier transform infrared spectroscopy showed that CaO2 changed the structures and functional groups of humus and lignocellulose, making them transform to be biodegradable. GC/MS analyses exhibited that the degradation products of humus and lignocellulose included several types of small molecular organics such as ester-like, acid-like, and alcohol-like substances. Further investigation demonstrated that substantial methane could be produced from these degradation products. It was also found that the presence of recalcitrant organics was detrimental to anaerobes relevant to anaerobic digestion, and the degradation of such recalcitrant organics mitigated their inhibitions to the anaerobes. Model-based analysis suggested that CaO2 pretreatment increased the maximum methane yield and methane production rate, which were consistent with the analysis above.
Wang, D, Tawk, M, Indraratna, B, Heitor, A & Rujikiatkamjorn, C 2019, 'A mixture of coal wash and fly ash as a pavement substructure material', Transportation Geotechnics, vol. 21, pp. 100265-100265.
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Wang, D, Wang, Y, Liu, X, Xu, Q, Yang, Q, Li, X, Zhang, Y, Liu, Y, Wang, Q, Ni, B-J & Li, H 2019, 'Heat pretreatment assists free ammonia to enhance hydrogen production from waste activated sludge', Bioresource Technology, vol. 283, pp. 316-325.
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© 2019 Elsevier Ltd Controlling free ammonia in an anaerobic fermenter at pertinent levels is reported recently to be an economically attractive and practically feasible approach to enhance hydrogen yield from waste activated sludge (WAS). This paper reports a new technology for WAS dark fermentation, i.e., using heat pretreatment (70 °C for 60 min) to assist free ammonia for further improving hydrogen yield. The experimental results showed that the accumulative hydrogen production from combined reactors was promoted from 12.3 to 19.2 mL/g VSS (volatile suspended solids), the maximum of which was 1.8, 2.7, and 7.1 times of that from sole free ammonia (131.9 mg NH3-N/L), sole heat, and blank reactors, respectively. Mechanism explorations showed that the combination strategy significantly enhanced WAS disintegration, providing more substrates for hydrogen production. Moreover, the combination suppressed activities of all microbes associated with anaerobic fermentation, but its inhibition to hydrogen consumers was much severer than that to other microbes.
Wang, D, Wu, C, Huang, W & Zhang, Y 2019, 'Vibration investigation on fluid-structure interaction of AP1000 shield building subjected to multi earthquake excitations', Annals of Nuclear Energy, vol. 126, pp. 312-329.
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© 2018 Elsevier Ltd Fluid-structure interaction (FSI) between water and water tank of AP1000 nuclear power plant has always been a hot topic because the gravity water tank plays a key role in protecting structural safety in an emergency such as an earthquake. The main target of this study is to investigate the FSI effect on structural dynamic responses of AP1000 shield building with filled and empty water tanks and to explore the most reasonable height of water level for reducing seismic response under inputs of multi three-direction earthquake excitations. For this purpose, method of nonlinear FSI algorithm of finite element is employed based on ANSYS platform. The numerical procedure is validated by comparison with theoretical calculation and existing experimental results of fluid free vibration and structural seismic responses in the situation of El Centro wave. Based on the validated numerical model, a series of numerical simulations on seven partially-filled models in six natural and one artificial earthquake are carried out and corresponding results, such as peak acceleration & displacement, floor response spectrum and structural base shear, are studied comparatively in details. Discussions of this study show that the partially-filled shield building appears significant FSI effect, which generates great influence on structural dynamic characteristics and responses. Reasonable design of the water level can contribute to reducing structural responses and improving seismic safety.
Wang, D, Wu, C, Zhang, Y & Li, S 2019, 'Study on vertical vibration control of long-span steel footbridge with tuned mass dampers under pedestrian excitation', Journal of Constructional Steel Research, vol. 154, pp. 84-98.
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© 2018 Elsevier Ltd This paper aims to study crowd-induced vibration control of long-span steel footbridges with different dynamic characteristics by combining methods of site measurement and numerical simulation. Four kinds of footbridge models with sensitive vertical natural frequencies of easily generating human-bridge resonance under pedestrian loading are designed based on an actual steel footbridge. The numerical models are firstly validated by comparative investigation between the site measurement and the simulation. Detailed study on dynamic responses of the four footbridges with and without controlling systems of tuned mass damper (TMD) and multiple tuned mass damper (MTMD) is then conducted under 13 cases of crowd random excitations, rhythmic running and jumping excitations. Results show that the numerical simulation agrees well with the site measurement data. TMD system is found to be highly efficient in reducing vibration responses only when the excitation frequency is basically consistent with the structural natural frequency, which obviously limits the application of TMD system in footbridges as wider excitation frequency bandwidth is caused by human activities. MTMD system are demonstrated to be with higher vibration absorption robustness appearing predominant and stable capacity of reducing structural vibrations under all the crowd random and rhythmic excitations for the four footbridges.
Wang, D, Wu, C, Zhang, Y, Ding, Z & Chen, W 2019, 'Elastic-plastic behavior of AP1000 nuclear island structure under mainshock-aftershock sequences', Annals of Nuclear Energy, vol. 123, pp. 1-17.
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© 2018 Elsevier Ltd This paper studies dynamic responses of AP1000 nuclear island structure in strong earthquake sequences. A numerical model to simulate nuclear structural behaviors in earthquake is validated by comparison with data from a previous study on a nonlinear dynamic analysis of a reinforced concrete shield building. The validated numerical model is then used to carry out a series of parametric analyses with 112 computational cases so as to determine influence of strong aftershocks on structural elastic-plastic behavior considering input of three-dimensional ground motions. The results indicate that the influence of aftershocks on structural horizontal/vertical dynamic responses is very small in design basis earthquake sequences. However, the influence must be considered seriously in beyond-design basis earthquake sequences as values of RMVs (Ratio of Mean Value) deviating IPRs (Input Peak Ratio) obviously, which means structural dynamic responses are greatly changed in strong aftershocks. Damage aggravating effect induced by strong aftershocks can cause severe damage of structural members and it is found the greater the magnitude of aftershocks, the severer the aggravation effect. Although earthquake input energy is mostly dissipated by damping energy, plastic damage energy plays considerable role in strong aftershocks as it shares beyond 8 percent of the total input energy, which is 10 times more compared to design basis earthquake sequences.
Wang, D, Zhang, D, Xu, Q, Liu, Y, Wang, Q, Ni, B-J, Yang, Q, Li, X & Yang, F 2019, 'Calcium peroxide promotes hydrogen production from dark fermentation of waste activated sludge', Chemical Engineering Journal, vol. 355, pp. 22-32.
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© 2018 Elsevier B.V. Calcium peroxide (CaO2), one of versatile and harmless inorganic peroxy compounds, has been recently used as a highly effective oxidant to degrade pollutants in sludge and a method to achieve sludge resource utilization. However, its impact on hydrogen production has never been studied before. This investigation therefore aims to fill this knowledge gap. Results indicated that with CaO2 increased from 0.05 to 0.25 g/g VSS (volatile suspended solids), the maximum hydrogen yield increased from 0.77 to 10.55 mL/g VSS. The mechanism studies revealed that CaO2 accelerated the breakage and death of sludge cells. Excitation emission matrix (EEM) analyses further indicated that CaO2 increased the biodegradability of the released substances, which could provide more biodegradable organics for the following reactions. Although CaO2 caused inhibitions to some extents to all the tested microbes, its inhibition to hydrogen consumers was much severer than that to hydrolytic microbes and hydrogen producers. The enzyme analyses also demonstrated that the suppression of calcium peroxide to the activities of enzymes related to hydrogen consumption process was much severer than that to the activities of the activities of enzymes related to hydrogen production process. Further investigations exhibited that alkali, [rad]O2− and [rad]OH radicals, were the major intermediate products of CaO2 decomposition. All of them were verified to contribute the increased hydrogen production, and their contributions were in the order of alkali > [rad]O2− > [rad]OH. This is the first work demonstrating that CaO2 can enhance hydrogen production from WAS. The findings reported in our paper not only expand the application field of CaO2 but also deepen the understanding of the CaO2-involved sludge fermentation process.
Wang, D, Zhang, Y, Wu, C, Xue, G & Huang, W 2019, 'Seismic performance of base-isolated AP1000 shield building with consideration of fluid-structure interaction', Nuclear Engineering and Design, vol. 353, pp. 110241-110241.
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© 2019 Elsevier B.V. Seismically-induced FSI effect on dynamic responses of AP1000 shield building with base isolation is focused in this study using numerical simualtion. The numerical model is firstly validated by comparison with existing experimental results, which is capable of simulating dynamic behaviors of the water partially-filled shield building with seismic isolation using high damping rubber (HDR) bearings. The influences of FSI on seismic performance of the base-isolated and base-fixed AP1000 shield building with various water levels and on the corresponding isolation effectiveness are comparatively explored in details. Results show that base isolation can reduce the fundamental frequency of the shield building and make it close to water sloshing frequency. It is necessary to ensure an reasonable isolation design to keep the fundamental frequency away from the sloshing frequency and then to avoid the water resonance. Seismic isolation can offer a substantial benefit for the earthquake-resistant design of the shield building even filled with different levels of water, because the structural primary resonance is effectively transformed to the sub-resonance by application of base isolation. Dynamic responses of base-isolated models are influenced significantly by FSI and an optimal water level ratio of 0.8 is suggested to achieve excellent seismic performance for such structures.
Wang, H, Li, Y, Zhang, G & Wang, J 2019, 'Effect of temperature on rheological properties of lithium-based magnetorheological grease', Smart Materials and Structures, vol. 28, no. 3, pp. 035002-035002.
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© 2019 IOP Publishing Ltd. This paper investigates the impact of temperature on the rheological properties of magnetorheological (MR) grease containing carbonyl iron suspended in lithium-based grease Lithium-based MR grease with 70% weight fraction of carbonyl iron is firstly prepared by mechanical mixing. The apparent viscosity and shear stress as a function of shear rate under different temperatures and magnetic field strengths are measured and discussed. It is found that the influence of temperature on apparent viscosity reduces with the increase of magnetic field strength. The dynamic properties of MR grease are obtained under oscillatory shear test. The influences of strain amplitude, driving frequency and magnetic field on the dynamic properties of MR grease at different temperature are discussed. The results demonstrate that the enhancement of temperature leads to the increase of storage modulus and the reduction of the loss factor. Microstructural variation of grease matrix at different temperature is proposed as an explanation of the rheological changes of MR grease.
Wang, Q, Gong, Y, Liu, S, Wang, D, Liu, R, Zhou, X, Nghiem, LD & Zhao, Y 2019, 'Free Ammonia Pretreatment To Improve Bio-hydrogen Production from Anaerobic Dark Fermentation of Microalgae', ACS Sustainable Chemistry & Engineering, vol. 7, no. 1, pp. 1642-1647.
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© 2018 American Chemical Society. Microalgae are third generation feedstocks for bio-hydrogen production to achieve a low carbon economy. Nevertheless, the bio-hydrogen production from microalgae is generally low. In this study, an innovative free ammonia (FA, i.e., NH 3 ) pretreatment technology was first demonstrated to improve bio-hydrogen production from the secondary effluent cultivated microalgae during the anaerobic dark fermentation experiments. Scanning electron microscopy revealed that FA pretreatment disrupted microalgae surface morphology. The soluble chemical oxygen demand (SCOD) release increased from 0.01 g SCOD/g VS microalgae (VS = volatile solids) to 0.05-0.07 g SCOD/g VS microalgae after FA pretreatment of 240-530 mg NH 3 -N/L for 1 day, indicating the enhanced microalgae solubilization. Dark fermentation bio-hydrogen potential experiments showed that bio-hydrogen production from microalgae was substantially improved following FA pretreatment of 240-530 mg NH 3 -N/L. The bio-hydrogen production potential and maximum bio-hydrogen production rate increased from 18.2 L H 2 /kg VS microalgae and 2.5 L H 2 /kg VS microalgae/d to 19.9-22.1 L H 2 /kg VS microalgae and 3.1-3.8 L H 2 /kg VS microalgae/d, respectively, after FA pretreatment of 240-530 mg NH 3 -N/L was implemented on the microalgae for 1 day. This FA technology follows a circular economic model because the required FA is from the FA rich dark fermentation liquid, which is a wastewater treatment waste.
Wang, Q, Sun, J, Liu, S, Gao, L, Zhou, X, Wang, D, Song, K & Nghiem, LD 2019, 'Free ammonia pretreatment improves anaerobic methane generation from algae', Water Research, vol. 162, pp. 269-275.
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© 2019 Elsevier Ltd Anaerobic methane generation from algae is hindered by the slow and poor algae biodegradability. A novel free ammonia (NH3 i.e. FA) pretreatment technology was proposed in this work to enhance anaerobic methane generation from algae cultivated using a real secondary effluent. The algae solubilisation was 0.05–0.06 g SCOD/g TCOD (SCOD: soluble chemical oxygen demand; TCOD: total chemical oxygen demand) following FA pretreatment of 240–530 mg NH3–N/L for 24 h, whereas the solubilisation was only 0.01 g SCOD/g TCOD for the untreated algae. This indicates that FA pretreatment at 240–530 mg NH3–N/L could substantially enhance algae solubilisation. Biochemical methane potential tests revealed that FA pretreatment on algae at 240–530 mg NH3–N/L is able to significantly enhance anaerobic methane generation. The hydrolysis rate (k) and biochemical methane potential (P0) of algae increased from 0.21 d−1 and 132 L CH4/kg TCOD to 0.33–0.50 d−1 and 140–154 L CH4/kg TCOD, respectively, after the algae was pretreated by FA at 240–530 mg NH3–N/L. Further analysis indicated that FA pretreatment improved k of both quickly and slowly biodegradable substrates, and also increased P0 of the slowly biodegradable substrate although it negatively affected P0 of the quickly biodegradable substrate. This FA technology is a closed-loop technology.
Wang, Q, Wu, D, Tin-Loi, F & Gao, W 2019, 'Machine learning aided stochastic structural free vibration analysis for functionally graded bar-type structures', Thin-Walled Structures, vol. 144, pp. 106315-106315.
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© 2019 Elsevier Ltd This paper presents a machine learning aided stochastic free vibration analysis for functionally graded (FG) bar-type structures through finite element method (FEM). The considered system uncertainties including the constituent material properties, the dimensions of structural members, and the degree of the gradation of the FGM are incorporated. A novel kernel-based machine learning technique, namely the extended support vector regression (X-SVR), is presented to estimate the governing relationship between the uncertain system parameters and the structural natural frequencies. Subsequently, by applying the Monte-Carlo Simulation (MCS) through the established regression model, various types of statistical characteristics (i.e., mean, standard deviation, probability density function or PDF, and cumulative distribution function or CDF) of structural natural frequencies can be effectively established. Four numerical examples including test functions and practically stimulated engineering structures are thoroughly investigated herein to demonstrate the accuracy, applicability, and computational efficiency of the proposed approach.
Wang, R, Hao, Q, Feng, J, Wang, G-C, Ding, H, Chen, D & Ni, B 2019, 'Enhanced separation of photogenerated charge carriers and catalytic properties of ZnO-MnO2 composites by microwave and photothermal effect', Journal of Alloys and Compounds, vol. 786, pp. 418-427.
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© 2019 Elsevier B.V. To improve the solar energy utilization and photodegradation efficiency of ZnO and α-MnO2, ZnO/MnO2 composite materials were prepared by a facile method. The materials are characterized by XRD, Raman spectra, X-ray photoelectron spectroscopy, scanning electronic microscopy, transmission electron microscopy, and UV–vis diffuse reflection spectroscopy. The photocatalytic activity and microwave-assisted photocatalytic activity of the composite are much higher than that of ZnO or α-MnO2. The main active species in the reaction progress were confirmed by electron paramagnetic resonance spectra and trapping experiments. According to the DFT calculation result and photothermal images, the enhanced catalytic activity is attributed to the photothermal and microwave-assisted effect. The addition of α-MnO2 improves the absorption of light and microwave by the composite, which can further heat up the catalysts. As a result, the separation of photogenerated charge carriers is accelerated. Finally, a mechanism for the enhanced catalytic performance of the composite materials was proposed.
Wang, W, Wu, C & Liu, Z 2019, 'Compressive behavior of hybrid double-skin tubular columns with ultra-high performance fiber-reinforced concrete (UHPFRC)', Engineering Structures, vol. 180, pp. 419-441.
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© 2018 Elsevier Ltd This study presents the results of an experimental program on the compressive behavior of hybrid fiber-reinforced polymer (FRP)-concrete-steel double-skin tubular columns (DSTCs) with ultra-high performance fiber-reinforced concrete (UHPFRC). In total 40 specimens, including 32 hybrid DSTCs and eight FRP confined solid concrete (FCSC) specimens, were prepared and tested under axial compression. In addition to hybrid UHPFRC DSTCs, hybrid DSTCs with ultra-high performance concrete without steel fiber addition (UHPC), high-strength concrete (HSC), and normal-strength concrete (NSC) were also tested. The investigated parameters included the FRP tube thickness, steel tube thickness, void ratio, steel fiber addition, concrete type, UHPFRC-filling inside the steel tube, and the column type. The test results indicate that the hybrid UHPFRC DSTCs can exhibit highly ductile behavior when a thick FRP tube is used. However, due to the ultra-high strength and the dense microstructure of UHPFRC, the hybrid UHPFRC DSTCs are likely to exhibit more brittle behavior than the hybrid DSTCs with NSC and HSC. Even though a high confinement level is provided, sudden stress reduction or stress fluctuations can be observed for the UHPFRC in hybrid DSTCs. The influences of FRP tube thickness, void ratio, steel fiber addition, and UHPFRC-filling inside the steel tube on the compressive behavior of the hybrid UHPFRC DSTCs are significant, while the influence of steel tube thickness is insignificant. Moreover, when compared to the FCSC specimens, the presence of an inner void is beneficial for the compressive behavior of UHPFRC in the hybrid DSTCs, especially when a thick FRP tube is used. Furthermore, the performance of existing stress-strain model to predict the compressive behavior of UHPFRC in the hybrid DSTCs is investigated.
Wang, W, Wu, C, Li, J, Liu, Z & Lv, Y 2019, 'Behavior of ultra-high performance fiber-reinforced concrete (UHPFRC) filled steel tubular members under lateral impact loading', International Journal of Impact Engineering, vol. 132, pp. 103314-103314.
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© 2019 This study investigates the behavior of ultra-high performance fiber-reinforced concrete (UHPFRC) filled steel tubular (UHPFRCFST) members under lateral impact loading. A total of five specimens were prepared and tested under lateral impact loading. All specimens were 168 mm in diameter and 2000 mm in length. In addition to UHPFRCFST members, normal strength concrete (NSC) filled steel tubular (NSCFST) members were also tested for comparison purpose. Other investigated parameters in this study include the impact energy and the presence of an inner void. The test results show that as compared to the NSCFST members, the UHPFRCFST members exhibit higher lateral impact resistance with higher peak and plateau impact forces, smaller deflection, and less local indentation. With the increase of impact energy, the peak impact force, the impact duration, and the deflection of the UHPFRCFST members are increased, while the plateau impact force is almost kept constant. Moreover, the presence of an inner void does not deteriorate the lateral impact resistance of the UHPFRCFST members. Finite element (FE) model was then developed and validated by the test results in this study. Afterwards, full-range analysis was performed to investigate the damage evolution, sectional bending moment distribution, and the interactions between the steel tube and the concrete during the impact process. Finally, detailed parametric analyses were carried out to investigate the influences of different parameters on the lateral impact behavior of UHPFRCFST members.
Wang, W, Wu, C, Li, J, Liu, Z & Zhi, X 2019, 'Lateral impact behavior of double-skin steel tubular (DST) members with ultra-high performance fiber-reinforced concrete (UHPFRC)', Thin-Walled Structures, vol. 144, pp. 106351-106351.
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© 2019 Elsevier Ltd This study investigates the lateral impact behavior of double-skin steel tubular (DST) members with ultra-high performance fiber-reinforced concrete (UHPFRC). A total of six specimens were prepared and tested under lateral impact loading. In addition to UHPFRC filled DST members, normal strength concrete (NSC) filled DST member was also tested for comparison. Other investigated parameters in this study include the impact energy, the outer steel tube thickness, the inner steel tube thickness, and the presence of axial force. The test results demonstrate that the UHPFRC filled DST members exhibit significantly higher lateral impact resistance capacity than the NSC filled DST member. The impact energy and the outer steel tube thickness significantly affect the lateral impact behavior of UHPFRC filled DST members, while the influence of inner steel tube thickness is insignificant. With the applied axial force in this study, the influence of axial force is also insignificant. Afterwards, numerical model was developed and validated by the present test results. Based on the validated numerical model, the mid-span bending moment distributions and the stress wave propagations were investigated. Finally, parametric analyses were carried out to investigate the influences of different parameters on the lateral impact behavior of UHPFRC filled DST members.
Wang, Y, Fan, S, Liao, F, Zheng, X, Huang, Z, Wang, Y & Han, X 2019, 'In situ formation and superior lithium storage properties of tentacle-like ZnO@NC@CNTs composites', Nanoscale Advances, vol. 1, no. 3, pp. 1200-1206.
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A novel structure of double carbon coated tentacle-like ZnO composite has been synthesized, which delivers remarkable Li+ storage properties.
Wang, Y, Wang, D, Chen, F, Yang, Q, Ni, B-J, Wang, Q, Sun, J, Li, X & Liu, Y 2019, 'Nitrate addition improves hydrogen production from acidic fermentation of waste activated sludge', Chemosphere, vol. 235, pp. 814-824.
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© 2019 Elsevier Ltd In this work, a low-cost alternative method (i.e., adding nitrate into WAS) to significantly enhance hydrogen production was reported. Experimental results showed that with an increase of nitrate addition from 0 to 362 mg/L, the maximal hydrogen production from acidic (pH 5.5) fermentation of WAS obviously increased from 12.6 ± 0.5 to 19.3 ± 0.9 mL per gram volatile suspended solids (VSS). The mechanism investigations illustrated more substrates were provided for subsequent hydrogen production. Although the nitrate added inhibited all the biological processes, its inhibition to the hydrogen consumption processes was much severer than that to the hydrogen production processes. The enzyme analyses on the long-term semi-continuous fermenters showed that the nitrate addition slightly inhibited the relative activities of protease, butyrate kinase, acetate kinase, CoA-transferase, and [FeFe] hydrogenase but largely suppressed the relative activities of coenzyme F420, carbon monoxide dehydrogenase, and adenylyl sulfate reductase.
Wang, Z, Chen, X-M, Ni, B-J, Tang, Y-N & Zhao, H-P 2019, 'Model-based assessment of chromate reduction and nitrate effect in a methane-based membrane biofilm reactor', Water Research X, vol. 5, pp. 100037-100037.
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© 2019 Zhejiang University Chromate contamination can pose a high risk to both the environment and public health. Previous studies have shown that CH4-based membrane biofilm reactor (MBfR) is a promising method for chromate removal. In this study, we developed a multispecies biofilm model to study chromate reduction and its interaction with nitrate reduction in a CH4-based MBfR. The model-simulated results were consistent with the experimental data reported in the literature. The model showed that the presence of nitrate in the influent promoted the growth of heterotrophs, while suppressing methanotrophs and chromate reducers. Moreover, it indicated that a biofilm thickness of 150 μm and an influent dissolved oxygen concentration of 0.5 mg O2/L could improve the reactor performance by increasing the chromate removal efficiency under the simulated conditions.
Wei, J, Li, J & Wu, C 2019, 'An experimental and numerical study of reinforced conventional concrete and ultra-high performance concrete columns under lateral impact loads', Engineering Structures, vol. 201, pp. 109822-109822.
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© 2019 Elsevier Ltd This paper presents an experimental and numerical study on the dynamic behaviour of axially-loaded reinforced conventional concrete (RC) and ultra-high performance concrete (UHPC) columns against low-velocity impact loading. The test specimens were divided into two groups with square and circular cross-section shapes, and each group includes both RC and UHPC columns. The impact scenario was modelled with a drop weight falling freely on the column mid-span. Brittle failure with shear plug formation was observed in RC columns while UHPC columns remained a flexure response with minimal damage under severe impact loads. To further interpret the experimental data, detailed finite element (FE) models were developed for RC and UHPC columns. A Continuous Surface Cap Model (CSCM) which accounts for the triaxial material strength, post peak softening and strain rate effect was adopted for UHPC material. After validating the material and structural model based on the testing data, extensive numerical simulations were performed to predict the UHPC column residual loading capacity after lateral impacts. Impact mass-velocity (M-V) diagrams were derived for the UHPC column damage assessment, and analytical formulae which could be easily applied to generate M-V diagrams were derived based on parametric studies.
Wei, W, Huang, Q-S, Sun, J, Dai, X & Ni, B-J 2019, 'Revealing the Mechanisms of Polyethylene Microplastics Affecting Anaerobic Digestion of Waste Activated Sludge', Environmental Science & Technology, vol. 53, no. 16, pp. 9604-9613.
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Copyright © 2019 American Chemical Society. Polyethylene (PE) microplastics retained in sewage sludge inevitably enter the anaerobic digestion system. To date, no information has been reported on the mechanisms of PE microplastics affecting anaerobic digestion of waste activated sludge (WAS). This study evaluated the mechanisms using batch and continuous tests. Short exposure to PE microplastics at lower levels (i.e., 10, 30, and 60 particles/g-TS) did not significantly affect the methane production, but higher levels of PE microplastics (i.e., 100 and 200 particles/g TS) significantly (P = 0.006 and 0.0003) decreased methane production by 12.4-27.5%, with a lower methane potential and hydrolysis coefficient. In continuous test over 130 days, feeding WAS with 200 particles PE microplastics/g TS decreased vs destruction by up to 27.3% (P = 2.18 × 10-18) and resulted in a 9.1% (P = 0.002) increase in the volume of digested sludge for disposal. Correspondingly, the microbial community was shifted in the direction against anaerobic digestion. A mechanisms study revealed that the negative effect of PE microplastics was likely attributed to the induction of reactive oxygen species (ROS) rather than the released acetyl tri-n-butyl citrate. The generation of ROS caused a 7.6-15.4% reduction of cell viability, thereby restraining sludge hydrolysis, acidification, and methanogenesis.
Wei, W, Huang, Q-S, Sun, J, Wang, J-Y, Wu, S-L & Ni, B-J 2019, 'Polyvinyl Chloride Microplastics Affect Methane Production from the Anaerobic Digestion of Waste Activated Sludge through Leaching Toxic Bisphenol-A', Environmental Science & Technology, vol. 53, no. 5, pp. 2509-2517.
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© 2019 American Chemical Society. The retention of polyvinyl chloride (PVC) microplastics in sewage sludge during wastewater treatment raises concerns. However, the effects of PVC microplastics on methane production from anaerobic digestion of waste activated sludge (WAS) have never been documented. In this work, the effects of PVC microplastics (1 mm, 10-60 particles/g TS) on anaerobic methane production from WAS were investigated. The presence of 10 particles/g TS of PVC microplastics significantly (P = 0.041) increased methane production by 5.9 ± 0.1%, but higher levels of PVC microplastics (i.e., 20, 40, and 60 particles/g TS) inhibited methane production to 90.6 ± 0.3%, 80.5 ± 0.1%, and 75.8 ± 0.2% of the control, respectively. Model-based analysis indicated that PVC microplastics at >20 particles/g TS decreased both methane potential (B0) and hydrolysis coefficient (k) of WAS. The mechanistic studies showed that bisphenol A (BPA) leaching from PVC microplastics was the primary reason for the decreased methane production, causing significant (P = 0.037, 0.01, 0.004) inhibitory effects on the hydrolysis-acidification process. The long-term effects of PVC microplastics revealed that the microbial community was shifted in the direction against hydrolysis-acidification and methanation. In conclusion, PVC microplastic caused negative effects on WAS anaerobic digestion through leaching the toxic BPA.
Wei, W, Zhang, Y-T, Huang, Q-S & Ni, B-J 2019, 'Polyethylene terephthalate microplastics affect hydrogen production from alkaline anaerobic fermentation of waste activated sludge through altering viability and activity of anaerobic microorganisms', Water Research, vol. 163, pp. 114881-114881.
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© 2019 Alkaline (especially pH 10) anaerobic fermentation of waste activated sludge (WAS) has been reported to be an effective approach for hydrogen production through inhibiting the homoacetogenesis and methanogenesis. However, the potential effect of the widespread microplastics in sludge on the performance of hydrogen production has never been reported. To fill this knowledge gap, the dominant polyethylene terephthalate (PET) microplastics in WAS were selected as the model microplastics to evaluate their influences on hydrogen production during alkaline anaerobic fermentation of WAS as well as the key mechanisms involved. Experimental results demonstrated that hydrogen production from WAS decreased in the presence of PET microplastics (i.e., 10, 30 and 60 particles/g-TS) compared to the control, with the hydrogen yield at 60 particles/g-TS being only 70.7 ± 0.9% of the control. Although the hydrogen consumption (i.e., homoacetogenesis and methanogenesis) was restrained under alkaline (pH 10) condition, PET microplastics inhibited hydrolysis, acidogenesis and acetogenesis in alkaline WAS anaerobic fermentation, leading to the inhibitory effect on hydrogen production. This was further confirmed by the microbial analysis, which clearly showed PET microplastics caused the shift of the microbial community toward the direction against hydrolysis-acidification. Mechanism studies revealed that PET microplastics carried on their negative influence mainly through leaching the toxic di-n-butyl phthalate (DBP). The reactive oxygen species (ROS) and live/dead staining tests indicated that the increased ROS was induced by PET microplastics, causing more cells dead, which further resulted in the decreased production of hydrogen.
Why, ESK, Ong, HC, Lee, HV, Gan, YY, Chen, W-H & Chong, CT 2019, 'Renewable aviation fuel by advanced hydroprocessing of biomass: Challenges and perspective', Energy Conversion and Management, vol. 199, pp. 112015-112015.
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Wicks, M, Millar, GJ & Altaee, A 2019, 'Process simulation of ion exchange desalination treatment of coal seam gas associated water', Journal of Water Process Engineering, vol. 27, pp. 89-98.
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© 2018 Elsevier Ltd The aim of this investigation was to develop an ion exchange process for the remediation of coal seam gas (CSG) associated water to make it suitable for beneficial reuse. The hypothesis was that computational modelling could accelerate the selection of appropriate ion exchange desalination strategies. Hence, we applied AqMB water process engineering software to predict which combination of weak acid cation (WAC), strong acid cation (SAC), weak base anion (WBA) and strong base anion (SBA) resins were most appropriate. Simulation results revealed that both SAC/WBA and SAC/SBA resin combinations were unable to meet water beneficial reuse standards for conductivity (< 950 μS/cm) due to the presence of bicarbonate species (4973 and 1918 μS/cm, respectively). Thus, a degasser unit was necessary to remove the large concentrations (ca. 1328 mg/L) of dissolved carbon dioxide formed due to decomposition of bicarbonate/carbonate species under acidic conditions in the cation resin stages. pH adjustment of effluent from the preferred SBA resin with acid not only did not meet solution conductivity guidelines but also raised the concentration of chloride or sulphate ions to levels, which may be detrimental for crop growth. Addition of a WAC resin allowed production of high quality water (either SAC/SBA/WAC or WAC/SAC/SBA combinations). To comply with sodium adsorption ratio requirements for irrigating soil it was suggested to apply micronized gypsum to the treated water. Economic evaluation suggested the treated water cost was A$1003 (WAC/SAC/SBA) to A$1276 (SAC/SBA/WAC) per ML treated which was comparable to estimated costs for a reverse osmosis desalination system.
Wijayaratna, KP, Cunningham, ML, Regan, MA, Jian, S, Chand, S & Dixit, VV 2019, 'Mobile phone conversation distraction: Understanding differences in impact between simulator and naturalistic driving studies', Accident Analysis & Prevention, vol. 129, pp. 108-118.
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A current issue within the driver distraction community centres around different findings regarding the impact of mobile phone conversation on driving found in driving simulators versus instrumented vehicles employed in real-world naturalistic driving studies (NDSs). This paper compares and contrasts the two types of studies and aims to provide reasons for the differences in findings that have been documented. A comprehensive review of literature and consultations with human factors experts highlighted that simulator studies tend to show degradation in driving performance, suggestive of increased crash risk as a result of mobile phone conversation. Whilst NDSs, at times, present data suggesting that mobile phone conversation distraction actually reduces crash risk. This study identifies that these differences may be attributed to behavioural hypotheses associated with driver self-regulation, arousal from cognitive loading, task displacement and gaze concentration - all of which need to be explicitly tested in future driving studies. Metric estimation and application was also revealed to be polarising results and the subsequent assessment of the crash risk. A common metric applied in this domain is the 'Odds Ratio', particularly prevalent in NDSs. This study presents a detailed investigation into the assumptions and application of the Odds Ratio which revealed the potential for over- and under-estimation of the metric depending on the core data and sampling assumptions. Furthermore, this research presents a comparative analysis of select driving simulator studies and an NDS considering only driving behaviour data as a means to consistently compare the findings of both methodologies. The findings from this investigation implores the need for greater consistency in the application of analysis methods and metrics across both simulator and NDSs. Improvements can yield a more robust platform to systematically compare and interpret data across both approaches, ultimatel...
Wu, C, Fang, J & Li, Q 2019, 'Multi-material topology optimization for thermal buckling criteria', Computer Methods in Applied Mechanics and Engineering, vol. 346, pp. 1136-1155.
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© 2018 Elsevier B.V. The structures in thermal environment often suffer from severe thermal expansion, potentially leading to buckling failure. This study aims to address this issue by proposing multi-material topology optimization for thermomechanical buckling problems. The density-based model with the rational approximation of material properties (RAMP) is adopted here for parameterization of multiple materials. The sensitivities of thermomechanical compliance and buckling are derived through the adjoint technique. The globally convergent version of the method of moving asymptotes (GCMMA) is employed to solve the non-monotonic topology optimization problem. In this study, two numerical examples are presented to illustrate the effectiveness of the proposed method, in which the total volume of multi-materials is minimized subject to thermoelastic compliance and buckling constraints. The examples exhibit significant difference in the final topologies for mechanical buckling and thermomechanical buckling optimization. The study demonstrates the importance of thermomechanical buckling criteria for the design of structures operating in a temperature-varying environment.
Wu, C, Gao, Y, Fang, J, Lund, E & Li, Q 2019, 'Simultaneous Discrete Topology Optimization of Ply Orientation and Thickness for Carbon Fiber Reinforced Plastic-Laminated Structures', Journal of Mechanical Design, vol. 141, no. 4.
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This study developed a discrete topology optimization procedure for the simultaneous design of ply orientation and thickness for carbon fiber reinforced plastic (CFRP)-laminated structures. A gradient-based discrete material and thickness optimization (DMTO) algorithm was developed by using casting-based explicit parameterization to suppress the intermediate void across the thickness of the laminate. A benchmark problem was first studied to compare the DMTO approach with the sequential three-phase design method using the free size, ply thickness, and stacking sequence of the laminates. Following this, the DMTO approach was applied to a practical design problem featuring a CFRP-laminated engine hood by minimizing overall compliance subject to volume-related and functional constraints under multiple load cases. To verify the optimized design, a prototype of the CFRP engine hood was created for experimental tests. The results showed that the simultaneous discrete topology optimization of ply orientation and thickness was an effective approach for the design of CFRP-laminated structures.
Wu, D, Liu, A, Huang, Y, Huang, Y, Pi, Y & Gao, W 2019, 'Time dependent uncertain free vibration analysis of composite CFST structure with spatially dependent creep effects', Applied Mathematical Modelling, vol. 75, pp. 589-606.
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© 2019 Elsevier Inc. In this study, the time dependent free vibration analysis of composite concrete-filled steel tubular (CFST) arches with various uncertainties is thoroughly investigated within a non-stochastic framework. From the practical inspiration, both uncertain material properties and mercurial creep effect associated with such composite materials are simultaneously incorporated. Unlike traditional non-probabilistic schemes, both spatially independent (i.e., conventional interval models) and dependent (i.e., interval fields) interval system parameters can be comprised within a unified uncertain free vibration analysis framework for CFST arches. For the purpose of achieving a robust framework of the time-dependent uncertain free vibration analysis, a new computational approach, which has been developed within the scheme of the finite element method (FEM), has been proposed for determining the extreme bounds of the natural frequencies of practically motivated CFST arches. Consequently, by successfully solving two eigenvalue problems, the upper and lower bounds of the natural frequencies of such composite structures with various uncertainties can be rigorously secured. The unique advantage of the proposed approach is that it can be effectively integrated within commercial FEM software with preserved sharp bounds on natural frequencies for any interval field discretisation. The competence of the proposed computational analysis framework has been thoroughly demonstrated through investigations on both 2D and3D engineering structures.
Wu, D, Wang, Q, Liu, A, Yu, Y, Zhang, Z & Gao, W 2019, 'Robust free vibration analysis of functionally graded structures with interval uncertainties', Composites Part B: Engineering, vol. 159, pp. 132-145.
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© 2018 Elsevier Ltd In this paper, a robust interval free vibration analysis for 3D functionally graded frame type engineering structure is presented through the finite element method (FEM). Uncertain material properties, which are including the Young's modulus and material density, of the functionally graded material are considered. Unlike the conventional uncertainty quantification through stochastic approach, the uncertain system inputs are modelled by the interval approach. Instead of straining on the precise statistical information of the uncertain parameters, only upper and lower bounds of the uncertain system inputs are required for valid structural safety assessment. By implementing the mathematical programming approach combined with the intrinsic characteristics of the non-deficient engineering structures, the upper and lower bounds of the natural frequencies of 3D functionally graded frame structure can be explicitly formulated by two independent eigen-problems. The sharpness and physical feasibility of the interval natural frequencies of the functionally graded structure can be well preserved. To demonstrate the competence of the proposed method, two numerical examples have been thoroughly investigated. In addition, diverse numerical investigations have been conducted to explore the impacts of uncertain material properties and the power-law index of the functionally graded materials on the overall structural performance.
Wu, P, Wu, C, Liu, Z & Hao, H 2019, 'Investigation of shear performance of UHPC by direct shear tests', Engineering Structures, vol. 183, pp. 780-790.
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© 2019 Elsevier Ltd Ultra-high performance concrete (UHPC) has been applied widely in modern structure construction. The outstanding mechanical properties of UHPC not only enable strong yet slim structural designs but also highlight its potential in protective structural constructions against extreme loads. In this study, the shear transfer behaviors of UHPC are investigated by push-off tests on Z-shaped specimens, investigating the influences of the microsteel fiber volume ratio and stirrup reinforcement ratio on the shear strength, shear slip, and shear crack width of UHPC. The test results indicate that using a microsteel fiber can enhance the shear strength of UHPC specimens. Within a reasonable range of the steel fiber volume ratio (optimum volume ratio ranges from 0% to 2.5% for microsteel fiber), the shear strength and shear slip of UHPC increase significantly, and the shear crack width reduces with an increasing steel fiber volume ratio. Additionally, the ductility, shear strength, and shear slip of UHPC increase significantly, and the shear crack width reduces with increasing stirrup ratio. Finally, the simplified empirical equations for the ultimate shear strengths of UHPC specimens are deduced, and indicate good agreement with the experimental results.
Wu, Y, Song, K, Sun, X, Li, L, Wang, W, Wang, Q & Wang, D 2019, 'Effects of free nitrous acid and freezing co-pretreatment on sludge short-chain fatty acids production and dewaterability', Science of The Total Environment, vol. 669, pp. 600-607.
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© 2019 Elsevier B.V. Short-chain fatty acids (SCFAs) as recoverable carbon source from waste activated sludge anaerobic fermentation process have aroused wide concern. In this study, free nitrous acid (FNA) and freezing pretreatments were combined to enhance SCFAs yield and fermented sludge dewaterability in the anaerobic fermentation system. The effects of different FNA concentrations and different freezing conditions (with or without curing stages) were analysed and compared. The results indicated that combining 1.07 mg N/L FNA with 48 h continuous freezing at −5 °C, raised SCFAs production from 6.7 mg COD/g volatile suspended solids (VSS) for the blank (no pretreatment) up to 124.0 mg COD/g VSS. In addition, the minimal water content of the treated fermented sludge cake was 78.11%, which was less than that of the blank (81.22%). SCFAs production and dewaterability enhancement could be attributed to sludge disintegration induced by the co-pretreatment, which led to sludge solubilisation, organics release, methanogenesis inhibition and particle size variation. This study implied that FNA and freezing co-pretreatment has the potential to enhance SCFAs production and sludge dewaterability in wastewater treatment plants.
Wu, Y, Song, K, Sun, X, Ngo, H, Guo, W, Nghiem, LD & Wang, Q 2019, 'Mechanisms of free nitrous acid and freezing co-pretreatment enhancing short-chain fatty acids production from waste activated sludge anaerobic fermentation', Chemosphere, vol. 230, pp. 536-543.
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© 2019 Elsevier Ltd Free nitrous acid (FNA) or freezing has been recently utilized as an efficient pretreatment method to increase short-chain fatty acids (SCFAs) yield from waste activated sludge (WAS) anaerobic fermentation (AF). But until now, the performances and mechanisms of the co-pretreatment for SCFAs production are unknown. This research aimed to investigate the AF mechanisms through studying its influence on sludge solubilization and related bioprocesses. WAS was pretreated for 48 h with FNA (1.07 mg N/L), freezing (−5 °C) and combination of FNA and freezing (0.53–2.13 mg N/L FNA at −5 °C), respectively, then conducted batch AF. Experimental results indicated that the optimal total SCFAs yield of 391.19 ± 5.54 mg COD/g VSS was achieved after 1.07 mg N/L FNA + freezing pretreatment at 9 days of AF, which was 2.2, 1.6 and 1.3-fold of the blank, freezing and FNA pretreated samples, respectively. The mechanisms analysis showed that co-pretreatment showed synergetic effects on sludge disintegration and solubilization, which could release more soluble substrates for SCFAs production. The co-pretreatment resulted in slight inhibition to hydrolysis and negligible inhibition to acidogenesis but severe inhibition to methanogenesis, maybe due to less endurance of methanogens.
Wu, Y, Wang, D, Liu, X, Xu, Q, Chen, Y, Yang, Q, Li, H & Ni, B 2019, 'Effect of poly aluminum chloride on dark fermentative hydrogen accumulation from waste activated sludge', Water Research, vol. 153, pp. 217-228.
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© 2019 Elsevier Ltd Poly aluminum chloride (PAC), an inorganic coagulant being accumulated in waste activated sludge (WAS) at substantial levels, are generally thought to inhibit WAS anaerobic fermentation. However, its effect on dark fermentative hydrogen accumulation has not been documented. This work therefore aimed to explore its effect on hydrogen accumulation and to elucidate the mechanism of how PAC affects hydrogen accumulation. Experimental results showed that with an increase of PAC addition from 0 to 20 mg Al per gram of total suspended solids (TSS), the maximal hydrogen yield from alkaline fermentation (pH 9.5) increased from 20.9 mL to 27.4 mL per gram volatile suspended solids (VSS) under the standard condition. Further increase of PAC to 30 mg Al/g TSS didn't cause a significant increase of hydrogen yield (p > 0.05). The mechanism explorations revealed that although PAC reduced the total short-chain fatty acid (SCFA) production, this reduction was mainly enforced to propionic acid fermentation type, which did not contribute hydrogen production. PAC suppressed all the microbial processes relevant to anaerobic fermentation to some extents, but its inhibition to hydrogen consumption was much severer than that to hydrogen production. Illumina Miseq sequencing analysis revealed that PAC did not affect the populations of SCFA and hydrogen producers, but the two hydrogen consumers, Acetoanaerobium and Desulfobulbus, were almost washed out by PAC. Among the three types of Al species present in the anaerobic fermentation systems, Ala (monomeric species) significantly affected the maximal hydrogen production potential while Alb (medium polymer species) and Alc (species of sol or gel) posed impacts on hydrogen production rate and the lag time.
Wu, Y, Wu, Z, Chu, H, Li, J, Ngo, HH, Guo, W, Zhang, N & Zhang, H 2019, 'Comparison study on the performance of two different gas-permeable membranes used in a membrane-aerated biofilm reactor', Science of The Total Environment, vol. 658, pp. 1219-1227.
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Wu, Z, Ambrožová, N, Eftekhari, E, Aravindakshan, N, Wang, W, Wang, Q, Zhang, S, Kočí, K & Li, Q 2019, 'Photocatalytic H2 generation from aqueous ammonia solution using TiO2 nanowires-intercalated reduced graphene oxide composite membrane under low power UV light', Emergent Materials, vol. 2, no. 3, pp. 303-311.
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We report for the first time the nitrogen doping of reduced graphene oxide (rGO) and TiO2 nanowires (NWs) when TiO2 NWs intercalated rGO membranes were immersed in ammonia aqueous solution under 8 W 254 nm UV irradiation. Such nitrogen-doped rGO/TiO2 NWs photocatalytic membrane produced H2 at a rate of 208 μmol h−1 g−1 under 8 W 254 nm UV irradiation, which is more than 14 times higher than the yield of the TiO2-P25 and 30-fold higher than TiO2 NWs alone under the same condition. Our study demonstrates a new synthesis route for doping nitrogen in rGO and TiO2, as well as the preliminary feasibility of hydrogen extraction from ammonia-containing wastewater with such a low-cost recyclable photocatalyst. In addition, the study illustrates the complexity of photocatalysis of ammonia aqueous solution, which involves multiple reactions in concurrence.
Xiao, Z, Li, Z, Guo, H, Liu, Y, Wang, Y, Yin, H, Li, X, Song, J, Nghiem, LD & He, T 2019, 'Scaling mitigation in membrane distillation: From superhydrophobic to slippery', Desalination, vol. 466, pp. 36-43.
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© 2019 Elsevier B.V. Scaling is a major obstacle to commercial application of membrane distillation (MD) for desalination. Contemporary understanding of scaling formation onto hydrophobic membrane was built on thermodynamic assumption of a non-slip condition. This research provides an alternative theory and a novel insight from a hydrodynamic view of slip boundary. We purposely selected three polyvinylidene difluoride (PVDF) membranes with different surface characteristics - namely a tailor made superhydrophobic micro-pillared (CF4-MP-PVDF), a micro-pillared (MP-PVDF) and a commercial (C-PVDF) membranes, for direct contact membrane distillation (DCMD) using a supersaturated CaSO4 feed. MD flux analysis showed that CF4-MP-PVDF was highly scaling resistant whereas the other two membranes were not. Nucleation energy barrier, wetting state factor and slip length were used to explain for the observed difference in scaling behavior. Results showed that hydrodynamic properties, such as the wetting state and slip length, play a critical role in determining the anti-scaling behavior of a hydrophobic membrane rather than the contact angle nor the thermodynamic nucleation energy barrier. New findings from this study serve as a new guideline for the fabrication of antiscaling membranes by creating a slippery surface.
Xie, K, Fu, Q, Qiao, GG & Webley, PA 2019, 'Recent progress on fabrication methods of polymeric thin film gas separation membranes for CO2 capture', Journal of Membrane Science, vol. 572, pp. 38-60.
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© 2018 Elsevier B.V. Membrane technology has been recognized as an attractive and environment-friendly technology for carbon capture due to its low expense (capital and operating), ease of operation as well as low energy consumption. Traditionally, the membrane materials are cast into dense membranes with a thickness of 50–150 µm and their gas separation properties are evaluated by the trade-off between permeability and selectivity. However, permeance (gas flux), rather than permeability, is more emphasized recently because the increase of the real gas flux through a membrane without the loss of selectivity has been recognized to be more important in industrial scenarios. The permeance is inversely proportional to the membrane thickness, and thus the thin film membranes with sub-micro scale selective layers as part of a composite membrane has drawn particular interests. In thin film membranes, the membrane fabrication technique as well as the membrane configuration design are more important than the membrane materials. However, the recent progress on membrane fabrication techniques, especially the bottom-up approaches for composite membranes, have not been fully reviewed and compared. This review focuses on the recent progress in fabrication techniques and approaches of the thin film (sub-micron) polymeric membranes for CO2 capture, the state-of-art performance of those membranes will be summarized, and future direction of thin film composite membrane will be discussed.
Xu, B, He, N, He, B, Li, D & Wu, S 2019, 'Experiment study on pipeline bending deformation monitoring based on distributed optical fiber sensor', Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument, vol. 40, no. 8, pp. 20-30.
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Scientific and reasonable pipeline safety monitoring technology is of great significance to pipeline engineering operation. This paper carries out the experiment study on pipeline bending deformation monitoring based on distributed optical fiber sensing technology. Aiming at the deficiency of existing distributed fiber deformation calculation method, a calculation method of pipeline bending deformation monitoring using distributed optical fiber sensor is proposed, and the calculation program of pipeline bending deformation using distributed optical fiber sensor based on MATLAB is written. The study results show that the proposed pipeline bending deformation monitoring method based on distributed optical fiber sensing technology has high overall measurement accuracy. Within the bending deformation range of 180 mm, the absolute error is less than 4 mm and the average relative error is within 2%. When the bending deformation is getting larger, the absolute error increases, however the average relative error is below 3.2%. The pipeline force analysis based on distributed optical fiber sensing technology was carried out preliminarily. The results show that the simulated pipeline shear force pattern is in good agreement with the theoretical pattern and the actual situation. The proposed pipeline bending deformation monitoring method based on distributed optical fiber sensing technology possesses high measurement accuracy and small error, which can meet the requirements of pipeline bending deformation monitoring and has good application prospect. The method is an ideal deformation monitoring technology and can also be extended to the application of other safety analysis such as pipeline force analysis and etc.
Xu, J, Cao, Z, Wang, Y, Zhang, Y, Gao, X, Ahmed, MB, Zhang, J, Yang, Y, Zhou, JL & Lowry, GV 2019, 'Distributing sulfidized nanoscale zerovalent iron onto phosphorus-functionalized biochar for enhanced removal of antibiotic florfenicol', Chemical Engineering Journal, vol. 359, pp. 713-722.
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© 2018 Aggregation of nZVI and sulfur-modified nZVI (S-nZVI) can lower its reactivity with contaminants in water. To overcome this limitation, we synthesized biochar-supported nZVI and S-nZVI using a phosphate pretreatment of the biochar (pBC) to uniformly distribute the nZVI and S-nZVI onto the biochar support. The participation of phosphorus groups in the synthesis, and the good distribution of S-nZVI on the pBC were confirmed by FTIR, SEM, XRD, and XPS. Pretreatment of the biochar led to smaller well-dispersed S-nZVI compared to S-nZVI supported on untreated biochar. This increased the surface area of the S-nZVI and the reaction rate with the antibiotic florfenicol (FF). The removal rate of FF by pBC-S-nZVI was 4.3 times higher than that by unsupported S-nZVI. Even though FF strongly adsorbed to the pBC support, FF was fully degraded based on the mass balance results. Surface area normalized reaction rate constants (kSA) for FF removal by S-nZVI, BC-S-nZVI, and pBC-S-nZVI were similar, suggesting that the enhanced reactivity is due to the greater dispersion of S-nZVI on the treated biochar. These results provide a simple pretreatment method for dispersing nZVI or S-nZVI onto biochar supports.
Xu, Q, Liu, X, Wang, D, Liu, Y, Wang, Q, Ni, B-J, Li, X, Yang, Q & Li, H 2019, 'Enhanced short-chain fatty acids production from waste activated sludge by sophorolipid: Performance, mechanism, and implication', Bioresource Technology, vol. 284, pp. 456-465.
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© 2019 Elsevier Ltd It was found in this study that the presence of sophorolipid (SL) enhanced the production of short-chain fatty acid (SCFA) from anaerobic fermentation of waste activated sludge (WAS). Experimental results showed that with an increase of SL addition from 0 to 0.1 g/g TSS, the maximal SCFA yield increased from 50.5 ± 4.9 to 246.2 ± 7.5 mg COD/g VSS. The presence of SL reduced the surface tension between hydrophobic organics and fermentation liquid, which thereby accelerated the disintegration of WAS and improved the biodegradability of the released organics. SL promoted the carbon/nitrogen ratio of the fermentation system, enhancing the conversion of proteins in WAS. Moreover, SL suppressed severely the activities of methanogens, probably due to the drop of pH caused by SL addition. Amplicon sequencing analyses revealed that SL increased the abundance of hydrolytic microbes such as Bacteroides sp. and Macellibacteroides sp., and SCFA producers (e.g., Acinetobacter sp.).
Xu, Q, Liu, X, Yang, G, Wang, D, Wang, Q, Liu, Y, Li, X & Yang, Q 2019, 'Free nitrous acid-based nitrifying sludge treatment in a two-sludge system obtains high polyhydroxyalkanoates accumulation and satisfied biological nutrients removal', Bioresource Technology, vol. 284, pp. 16-24.
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© 2019 Elsevier Ltd A novel strategy to achieve substantial polyhydroxyalkanoates (PHA) accumulation in waste activated sludge (WAS) was developed, which was conducted in a two-sludge system consisted of an anaerobic/anoxic/oxic reactor (AAO-SBR) and a nitrifying reactor (N-SBR), where the nitrifying-sludge was treated by free nitrous acid (FNA). Initially, 0.98 ± 0.09 and 1.46 ± 0.10 mmol-c/g VSS of PHA were respectively determined in the control-SBR and AAO-SBR. When 1/16 of nitrifying sludge was daily treated with 1.49 mg N/L FNA for 24 h, ∼46.5% of nitrite was accumulated in the N-SBR, ∼2.43 ± 0.12 mmol-c/g VSS of PHA was accumulated in WAS in AAO-SBR without deteriorating nutrient removal. However, nutrient removal of control-SBR was completely collapsed after implementing the same FNA treatment. Further investigations revealed that the activity and abundance of nitrite oxidizing bacteria (NOB) was decreased significantly after FNA treatment. Finally, sludge with high PHA level to generate more methane was confirmed.
Xu, R & Fatahi, B 2019, 'Impact of In Situ Soil Shear-Wave Velocity Profile on the Seismic Design of Tall Buildings on End-Bearing Piles', Journal of Performance of Constructed Facilities, vol. 33, no. 5, pp. 04019053-04019053.
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© 2019 American Society of Civil Engineers. In this study, a numerical investigation into how the shear wave velocity profile affects the seismic performance of tall buildings and foundations was carried out using FLAC3D software. The in situ soil profile and equivalent average soil profile, which reflect the actual soil shear wave velocity profile and the corresponding uniform time-averaged soil shear wave profile based on the actual profile, respectively, were studied. Overconsolidated soil near the ground surface was considered in the in situ soil profile. A 20-story building supported by an end-bearing pile foundation was designed and simulated. A fully coupled nonlinear dynamic analysis was carried out in the time domain to evaluate the seismic response of the structure and foundation system under strong earthquakes. The variations of the interface parameters with depth around the piles were considered according to the variations in the stiffness of surrounding soil with depth in the numerical model when the in situ soil profile was used. The predicted shear forces, maximum lateral deformation, and maximum interstory drifts of the building are presented and discussed, as are the maximum shear forces, maximum bending moments, and the maximum lateral deformation of the piles. The results indicate that the use of an actual shear wave velocity profile instead of an equivalent average profile gives design engineers the opportunity to optimize their design and achieve cost-effective solutions.
Xu, R & Fatahi, B 2019, 'Novel application of geosynthetics to reduce residual drifts of mid-rise buildings after earthquakes', Soil Dynamics and Earthquake Engineering, vol. 116, pp. 331-344.
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© 2018 Elsevier Ltd Geosynthetics have been used in variety of geotechnical engineering projects, such as ground improvement, erosion control, slope stabilisation and foundation strength improvement and they have been proved to be cost and time effective in many cases. In this study, a geosynthetic reinforced composite soil (GRCS) foundation system is proposed for seismic protection of mid-rise buildings supported by a shallow foundation potentially suffering from residual structural drift or permanent foundation settlement. To evaluate the proposed GRCS, a conventional reinforced concrete moment resisting building sitting on this composite ground under the earthquake excitations of 1978 Tabas, 1994 Northridge and 1995 Kobe was numerically simulated using FLAC3D software. The effect of soil-structure interaction (SSI) was captured using direct method of analysis adopting a three-dimensional numerical model. By adopting direct calculation method, the soil deposit, the geosynthetic reinforcement, the foundation and the structure were simulated simultaneously. Inelastic behaviour of the structure was considered, while hysteretic damping algorithm was adopted representing the variation of the shear modulus and corresponding damping ratio of the soil with cyclic shear strain capturing the energy dissipation characteristics of the soil. Both material and geometry nonlinearities were taken into account at the interface between the foundation and ground surface. The results are then presented in terms of mobilised tensile force in geosynthetic layers, the response spectra at bedrock and ground surface level, the shear force developed in the superstructure, the maximum foundation rocking angle, the maximum lateral deflection, the maximum inter-storey drift, and most importantly the residual inter-storey drift and permanent foundation settlement. The results showed that the proposed GRCS could offer design engineers a rational and cost-effective alternative solution to con...
Xu, S, Wu, C, Liu, Z & Shao, R 2019, 'Experimental investigation on the cyclic behaviors of ultra-high-performance steel fiber reinforced concrete filled thin-walled steel tubular columns', Thin-Walled Structures, vol. 140, pp. 1-20.
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© 2019 This paper presents an experimental investigation on the cyclic behaviors of ultra-high performance steel fiber reinforced concrete filled thin-walled steel tubular columns under combined axial compression and cyclic lateral displacement loading. The failure modes, hysteretic behaviors, envelop diagrams, ductile performance, stiffness degradation and energy dissipation capacity were analyzed in detail. Notably, the cyclic behaviors of referenced high strength concrete and normal strength concrete filled thin-walled steel tubular columns were also studied to get a better illustration of the cyclic behaviors of ultra-high-performance steel fiber reinforced concrete filled thin-walled steel tubular columns. Furthermore, the effects of steel tube thickness, axial compression ratio, volume ratio of steel fiber and slenderness on the cyclic behaviors of ultra-high-performance steel fiber reinforced concrete filled thin-walled steel tubular columns were also investigated in detail. The test results indicate that the high strength concrete filled thin-walled steel tubular columns represent a poor cyclic behavior. However, replacing high strength concrete with ultra-high performance steel fiber reinforced concrete to infill thin-walled steel tubes can get an excellent cyclic behavior. Moreover, the cyclic behavior of ultra-high performance steel fiber reinforced concrete filled thin-walled steel tubular columns is also much better than that of normal strength concrete filled thin-walled steel tubular columns.
Xu, X, Zhou, Y, Han, R, Song, K, Zhou, X, Wang, G & Wang, Q 2019, 'Eutrophication triggers the shift of nutrient absorption pathway of submerged macrophytes: Implications for the phytoremediation of eutrophic waters', Journal of Environmental Management, vol. 239, pp. 376-384.
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© 2019 Elsevier Ltd Ecologically restoring eutrophic water bodies by using submerged macrophytes is an economical, effective and sustainable technology worldwide. However, current understanding on the nutrient absorption pathway of submerged macrophytes in freshwater ecosystems, especially under different trophic states, is still limited. In this study, two strategically designed systems were established to form isolated units for preventing nutrient exchange amongst Potamogeton crispus, water column and sediments. Results showed that, in oligotrophic state, P. crispus mainly relied on their roots to absorb nutrients from sediments for maintaining stable growth, with the maximum average height, fresh weight and relative growth rate of 12.85 cm, 4.86 g ind −1 and 0.062, respectively. However, the eutrophic conditions (TN of 4 mg L −1 and TP of 0.3 mg L −1 ) triggered the shift of the nutrient absorption pathway from the roots to the shoots to some extent, that is, the shoots of P. crispus gradually became a remarkable pathway to directly absorb nutrients from the water column. Approximately 49.85% and 18.35% of total nitrogen (TN) and total phosphorus (TP) from overlying water were allocated to the shoots of P. crispus, but had no effects on the growth, photosynthesis and ecological stoichiometric differences (p > 0.05). Sediments acting as a nitrogen (N) source supported nearly 11.56% of TN for shoot uptake and simultaneously received around 13.33% of TP subsidy from the overlying water. The no longer sole dependence of submerged macrophytes on their root system to absorb N and phosphorus nutrients indicated that the ability of shoots to absorb nutrients increased with the gradual increase in nutrients in water column. These findings imply that the large specific surface area of shoots is beneficial for restoring eutrophic waters.
Xu, Y, Gao, Y, Wu, C, Fang, J & Li, Q 2019, 'Robust topology optimization for multiple fiber-reinforced plastic (FRP) composites under loading uncertainties', Structural and Multidisciplinary Optimization, vol. 59, no. 3, pp. 695-711.
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© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. This study proposes a non-deterministic robust topology optimization of ply orientation for multiple fiber-reinforced plastic (FRP) materials, such as carbon fiber–reinforced plastic (CFRP) and glass fiber–reinforced plastic (GFRP) composites, under loading uncertainties with both random magnitude and random direction. The robust topology optimization is considered here to minimize the fluctuation of structural performance induced by load uncertainty, in which a joint cost function is formulated to address both the mean and standard deviation of compliance. The sensitivities of the cost function are derived with respect to the design variables in a non-deterministic context. The discrete material optimization (DMO) technique is extended here to accommodate robust topology optimization for FRP composites. To improve the computational efficiency, the DMO approach is revised to reduce the number of design variables by decoupling the selection of FRP materials and fiber orientations. In this study, four material design examples are presented to demonstrate the effectiveness of the proposed methods. The robust topology optimization results exhibit that the composite structures with the proper ply orientations are of more stable performance when the load fluctuates.
Xue, C, Li, W, Li, J & Wang, K 2019, 'Numerical investigation on interface crack initiation and propagation behaviour of self-healing cementitious materials', Cement and Concrete Research, vol. 122, pp. 1-16.
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© 2019 Elsevier Ltd Based on the extended finite element method (XFEM) and cohesive surface (CS) technique, the interface cracks between healing agent and cementitious materials in the self-healing mortar beam under three-point bending are numerically investigated in this study. After obtaining original crack feature using XFEM, a parametric study was conducted to comprehensively discuss effects of the elastic ratio between self-healing agent and cementitious materials, bonding strength and fracture toughness of the self-healing agent-cementitious material interface on crack initiation and propagation. The results reveal that crack initiation seriously degrades stiffness of cementitious materials. Flexible healing agent increases the probability of new crack initiation and healed crack propagation, while stiffer healing agent induces obvious stress concentration around the interface, increasing fracture chance of interfacial zone. The numerical model and methodology developed in this study are useful to investigate the self-healing behaviours and develop high efficient self-healing cementitious materials.
Xue, C, Li, W, Li, J, Tam, VWY & Ye, G 2019, 'A review study on encapsulation‐based self‐healing for cementitious materials', Structural Concrete, vol. 20, no. 1, pp. 198-212.
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Encapsulation‐based self‐healing technology is an effective method for healing the crack‐deteriorated cementitious material. Encapsulation‐based self‐healing initiates by crack occurrence and progresses by chemical reaction of released self‐healing agents in the cracks, which are contained in capsules. In this paper, a review has been conducted on various healing agents, encapsulation techniques, as well as experimental approaches, basing on existing substantial studies. Recently, there is no consistent agreement on the effective criteria for evaluating encapsulation‐based self‐healing and mature solution for increasing the survival ratio of capsules during mixing. However, the polyurethane‐based healing agents filled in glass or ceramic tubes are popularly applied for self‐healing cementitious materials. Besides, the polymer capsules present promising attractions for engineering application. Mechanical strength and durability are the most widely used self‐healing efficiency assessment indexes. On the other hand, nondestructive technique and numerical modeling have also extensively adopted to visualize and evaluate the self‐healing behavior of cementitious materials. However, there are still some challenges, which require further investigations, such as behavior of crack propagation, kinetics of healing agent in discrete crack surfaces, effect of inserted capsules on the mechanical properties of self‐healed cementitious materials.
Xue, S, Zhang, X, Ngo, HH, Guo, W, Wen, H, Li, C, Zhang, Y & Ma, C 2019, 'Food waste based biochars for ammonia nitrogen removal from aqueous solutions', Bioresource Technology, vol. 292, pp. 121927-121927.
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© 2019 Elsevier Ltd Biochar derived from waste has been increasingly considered as a potential green adsorbent due to its significant ability and affordable production costs. This study prepared and evaluated 7 types of food waste-based biochars (FWBBs) (including meat and bone, starchy staples, leafy stemmed vegetables, nut husks, fruit pericarp, bean dreg and tea leaves). The impacts of raw materials, pyrolysis temperatures (300, 400, 500, 600 and 700 °C), and residence time (2 h and 4 h) on the removal of ammonia nitrogen at different ammonia nitrogen concentrations (5, 10, 20, 50, 100, 150 mg/L) were investigated. The batch equilibrium and kinetic experiments confirmed that a FWBB dosage of 3 g/L at 25 °C could remove up to 92.67% ammonia nitrogen. The Langmuir isotherm model had the best fit to equilibrium experimental data with a maximum adsorption capacity of 7.174 mg/g at 25 °C. The pseudo-second order kinetic model well describes the ammonia nitrogen adsorption.
Yang, G, Jiang, Y, Nimbalkar, S, Sun, Y & Li, N 2019, 'Influence of Particle Size Distribution on the Critical State of Rockfill', Advances in Civil Engineering, vol. 2019, pp. 1-7.
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In order to study the effect of particle size distribution on the critical state of rockfill, a series of large-scale triaxial tests on rockfill with different maximum particle sizes were performed. It was observed that the intercept and gradient of the critical state line in thee−p′plane decreased as the grading broadened with the increase in particle size while the gradient of the critical state line in thep′−qplane increased as the particle size increased. A power law function is found to appropriately describe the relationship between the critical state parameters and maximum particle size of rockfill.
Yang, G, Yan, X, Nimbalkar, S & Xu, J 2019, 'Effect of Particle Shape and Confining Pressure on Breakage and Deformation of Artificial Rockfill', International Journal of Geosynthetics and Ground Engineering, vol. 5, no. 2.
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© 2019, Springer Nature Switzerland AG. The rockfill exhibits a substantial amount of particle breakage when subjected to higher range of stresses. The deformations of rockfill under such excessive stresses often lead to failure and cannot be ignored. The degree of particle breakage is related to the type of the material as well as the particle shape. Based on this, artificially simulated rockfill materials with three different aggregate shapes (prism, cube, and cylinder) were prepared by cement paste-casting method. Through a series of medium-sized triaxial shear tests, the effects of confining pressure and particle shape on the fracture characteristics of the artificial rockfill and its secant modulus were investigated. The useful relationships between particle sphericity and roundness with deformation modulus and particle breakage rate were proposed.
Yang, S, Gao, B, Zhao, P, Wang, C, Shen, X, Yue, Q & Shon, HK 2019, 'The application of forward osmosis for simulated surface water treatment by using trisodium citrate as draw solute', Environmental Science and Pollution Research, vol. 26, no. 9, pp. 8585-8593.
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© 2019, Springer-Verlag GmbH Germany, part of Springer Nature. In this study, trisodium citrate was used as draw solute in forward osmosis (FO) due to its biodegradability and easy reuse after FO dilution. The effect of operating conditions on FO performance was investigated. The study focused on the long-term flux performance and membrane fouling when surface water was used as feed solution. A water flux of 9.8 LMH was observed using 0.5 M trisodium citrate as draw solution in PRO mode. In the long-term FO process, trisodium citrate showed a slight decrease in total flux loss (13.06%) after 20 h of operation. The membrane fouling was significantly reduced after a two-step physical cleaning. A considerable flux recovery (> 95%) of the fouled membrane was finally obtained. Therefore, this study proves the superiority of trisodium citrate as draw solution and paves a new way in applying FO directly for surface water reclamation.
Yang, Y, Wu, C, Liu, Z, Liang, X & Xu, S 2019, 'Experimental investigation on the dynamic behaviors of UHPFRC after exposure to high temperature', Construction and Building Materials, vol. 227, pp. 116679-116679.
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© 2019 Elsevier Ltd Split Hopkinson pressure bar (SHPB) tests were conducted to experimentally study the dynamic behaviors of ultra-high-performance fiber-reinforced concrete (UHPFRC) after being first exposed to elevated temperatures, followed by cooling. The dynamic stress–strain relationships were measured as key parameters to study the effects of high temperature on the dynamic behaviors of fire-damaged UHPFRC. In addition, dynamic increase factor (DIF) values for the dynamic compressive strength were generated. It was found that the strength of UHPFRC increased with the increase in strain rates with high temperatures. A significant difference in the dynamic compressive strength was found under two different temperature scenarios, i.e., elevated temperatures and cooling. Scanning electron microscopy (SEM) analysis was conducted to understand the macroscopic failure phenomenon, element composition and concrete hydration process. The results provide a basis for assessing the impact resistance and anti-collapse resistance of fire-damaged UHPFRC structures.
Yang, Z, Huang, Y, Liu, A, Fu, J & Wu, D 2019, 'Nonlinear in-plane buckling of fixed shallow functionally graded graphene reinforced composite arches subjected to mechanical and thermal loading', Applied Mathematical Modelling, vol. 70, pp. 315-327.
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© 2019 Elsevier Inc. The nonlinear in-plane buckling analysis for fixed shallow functionally graded (FG) graphene reinforced composite arches which are subjected to uniform radial load and temperature field is presented in this paper. The arch is composed of multiple graphene platelet reinforced composite (GPLRC) layers with gradient changes of concentration of graphene platelets (GPLs) in each layer. The principle of virtual work, combined with the effective materials properties estimated by the Halpin-Tsai micromechanics model for GPLRC layer, is used to derive the nonlinear buckling equilibrium equations of the FG-GPLRC arch, and then the analytical solutions for the limit point and bifurcation buckling loads are obtained. Comprehensive parametric studies are conducted to explore the effects of various distribution patterns and geometries of GPL, temperature field and arch geometry on the nonlinear equilibrium path and buckling behavior of the composite arch. The influence of temperature on the geometric parameters which are defined as switches between limit point buckling, bifurcation buckling and no buckling are also discussed. It is found that a higher temperature field can increase the buckling loads of the FG-GPLRC arch but reduce the value of the minimum geometric parameters that switching the buckling modes. The results also show that even a small amount of GPLs filler content can increase the buckling loads of the FG-GPLRC arch considerably, and distributing more GPLs near the surface layers is the best pattern to enhance the buckling performances of FG-GPLRC arches.
Yao, M, Ren, J, Akther, N, Woo, YC, Tijing, LD, Kim, S-H & Shon, HK 2019, 'Improving membrane distillation performance: Morphology optimization of hollow fiber membranes with selected non-solvent in dope solution', Chemosphere, vol. 230, pp. 117-126.
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© 2019 Elsevier Ltd This study aimed at improving membrane distillation (MD) performance by mixing various non-solvents (NSs) in polymer dope solutions. The effect of each NS on the inner structure and surface morphology of hollow fiber (HF) membrane was investigated. Membrane morphology is manipulated by controlling liquid-liquid (L-L) and solid-liquid (S-L) demixing time, which is a function of the viscosity and water affinity of dope solutions. Consequently, the addition of NSs altered membrane morphology by affecting the diffusion rate during NS induced phase separation (NIPS) process. The performance results showed that the dope solution composed of 11/71.2/17.8 wt% polyvinylidene fluoride (PVDF)/triethyl phosphate (TEP)/toluene produced the most promising HF membrane for MD. The optimal membrane demonstrated a unique bicontinuous structure with increased porosity and mean pore size. The addition of toluene as NS in dope solutions enhanced crystallization process, which increased the Young's modulus of membrane but slightly decreased its maximum tensile strength at break. The optimal PVDF HF membrane demonstrated a steady flux of 18.9 LMH at 60 °C/20 °C of feed/permeate temperatures and a salt rejection of 99.99% when tested for 72 h. The results suggest that incorporation of toluene as a NS into PVDF dope solutions can increase permeation performance in MD by enhancing the morphology of HF membranes.
Yao, M, Woo, YC, Ren, J, Tijing, LD, Choi, J-S, Kim, S-H & Shon, HK 2019, 'Volatile fatty acids and biogas recovery using thermophilic anaerobic membrane distillation bioreactor for wastewater reclamation', Journal of Environmental Management, vol. 231, pp. 833-842.
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© 2018 Elsevier Ltd The effects of bioreactor temperatures and salinities of an anaerobic membrane distillation bioreactor (anMDBR) on the permeation performance and their potential recovery of bioresources were fully examined in this study. To the best of our knowledge, this is the first study of a lab-scale anMDBR process utilizing sub-merged hollow fiber membranes. The hybrid system utilizing both membrane distillation (MD) and anaerobic bioreactors achieved 99.99% inorganic salt rejection regardless the operation temperatures and high initial flux from (2–4 L m−2 h−1) at 45–65 °C. However, after 7-day operation, the flux dropped by 16–50% proportional to the bioreactor temperatures. It was found that the effects of bioreactor temperatures had strong impacts on both the permeation performance and fouling behavior while salinity had insignificant effect. A compact non-porous fouling layer was observed on the membrane surface from the bioreactor operated at 65 °C while only a few depositions was found on the membrane from 45 °C bioreactor. In the present study, the optimal anMDBR temperature was found to be 45 °C, showing a balanced biogas production and membrane permeation performance including less fouling formation. At this bioreactor temperature (45 °C), the biogas yield was 0.14 L/g CODremoval, while maintaining a methane recovery of 42% in the biogas, similar recovery to those at bioreactor temperatures of 55 and 65 °C. The potential recovery of volatile fatty acids made anMDBR a more economically efficient system, in addition to its lower operation cost and smaller footprint compared with most other technologies for on-site wastewater treatment.
Yap, HC, Pang, YL, Lim, S, Abdullah, AZ, Ong, HC & Wu, C-H 2019, 'A comprehensive review on state-of-the-art photo-, sono-, and sonophotocatalytic treatments to degrade emerging contaminants', International Journal of Environmental Science and Technology, vol. 16, no. 1, pp. 601-628.
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© 2018, Islamic Azad University (IAU). Emerging contaminants (ECs) are commonly originated from personal care products, cosmetics, pharmaceuticals, pesticides, dioxins, polycyclic aromatic hydrocarbons (PAHs), and alkylphenolic compounds. Due to the huge development of these industries, these ECs have been constantly detected in wastewater, groundwater, and surface water in hazardous quantity. The discharge of these ECs into the environment causes considerable non-esthetic pollution and could be a great threat to the entire ecosystem. The common wastewater treatment plants (WWTPs) which consist of biological, physical, and chemical treatments such as activated sludge, filtration, adsorption, and coagulation are found to be ineffective for desired removal of ECs. In turn, various emerging advanced oxidation processes (AOPs) such as ultrasonic and ultraviolet irradiation with or without the presence of catalyst have raised great attention due to their great potential in remediation of ECs. This paper presents a critical review on types, recent occurrence, sources, environmental impacts, and emerging treatment methods applicable to treat ECs. The current research and applications of ultrasonic, ultraviolet, and combination of both irradiations to treat ECs in wastewater are particularly reviewed. The effect of key parameters on photo-, sono- and, sonophotocatalytic degradation of ECs are commendably accessed such as ultrasonic power, ultrasonic frequency, light intensity, ultraviolet wavelength, solution pH, oxidizing agents, chemical additives, catalyst dosage, and modification of catalyst. The possible reaction mechanisms of ECs degradation process and kinetic model study are also elucidated in detail. Lastly, future research directions and conclusions are proposed to strengthen the understanding on their fate in water. All this information is vital to predict the negative impacts of ECs on the receiving environment effectively.
Ye, X, Wang, S, Xiao, X, Sloan, S & Sheng, D 2019, 'Numerical Study for Compaction-Grouted Soil Nails with Multiple Grout Bulbs', International Journal of Geomechanics, vol. 19, no. 2, pp. 04018193-04018193.
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© 2018 American Society of Civil Engineers. A finite-element model was adopted to numerically simulate compaction-grouted soil nailswithmultiple grout bulbs. The numerical model was first verified by the corresponding experimental results. Then a series of numerical simulations were carried out to investigate the pull-out behavior of compaction-grouted soil nails with multiple grout bulbs. Numerical results show that the pull-out force increases with the increasing diameter of the grout bulb and the spacing between the grout bulbs. Furthermore, the pull-out displacement at failure of the soil nail decreases for the bigger grout bulb. Soil nails with larger back-end and smaller front-end grout bulbs experience the higher peak pull-out force and larger pull-out displacement at failure. Two types of failure surfaces were found for the soil nails with a double-grouted bulb, and those with a curved failure surface gave the largest pull-out displacement at failure. It indicates that the grouting point placed at the end of the nail rod is more preferable in field application. An equal spacing and grout bulb diameter can help to maximize the performance of a compaction-grouted soil nail with multiple grout bulbs.
Ye, Y, Jiao, J, Kang, D, Jiang, W, Kang, J, Ngo, HH, Guo, W & Liu, Y 2019, 'The adsorption of phosphate using a magnesia–pullulan composite: kinetics, equilibrium, and column tests', Environmental Science and Pollution Research, vol. 26, no. 13, pp. 13299-13310.
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A magnesia-pullulan (MgOP) composite has been developed to remove phosphate from a synthetic solution. In the present study, the removal of phosphate by MgOP was evaluated in both a batch and dynamic system. The batch experiments investigated the initial pH effect on the phosphate removal efficiency from pH 3 to 12 and the effect of co-existing anions. In addition, the adsorption isotherms, thermodynamics, and kinetics were also investigated. The results from the batch experiments indicate that MgOP has encouraging performance for the adsorption of phosphate, while the initial pH value (3-12) had a negligible influence on the phosphate removal efficiency. Analysis of the adsorption thermodynamics demonstrated that the phosphate removal process was endothermic and spontaneous. Investigations into the dynamics of the phosphate removal process were carried out using a fixed bed of MgOP, and the resulting breakthrough curves were used to describe the column phosphate adsorption process at various bed masses, volumetric flow rates, influent phosphate concentrations, reaction temperatures, and inlet pH values. The results suggest that the adsorption of phosphate on MgOP was improved using an increased bed mass, while the reaction temperature did not significantly affect the performance of the MgOP bed during the phosphate removal process. Furthermore, higher influent phosphate concentrations were beneficial towards increasing the column adsorption capacity for phosphate. Several mathematic models, including the Adams-Bohart, Wolboska, Yoon-Nelson, and Thomas models, were employed to fit the fixed-bed data. In addition, the effluent concentration of magnesium ions was measured and the regeneration of MgOP investigated.
Ye, Y, Ngo, HH, Guo, W, Chang, SW, Nguyen, DD, Liu, Y, Nghiem, LD, Zhang, X & Wang, J 2019, 'Effect of organic loading rate on the recovery of nutrients and energy in a dual-chamber microbial fuel cell', Bioresource Technology, vol. 281, pp. 367-373.
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This study aimed to assess the impacts of organic loading rate (OLR) (435-870 mgCOD/L·d) on nutrients recovery via a double-chamber microbial fuel cell (MFC) for treating domestic wastewater. Electricity generation was also explored at different OLRs, including power density and coulombic efficiency. Experimental results suggested the MFC could successfully treat municipal wastewater with over 90% of organics being removed at a wider range of OLR from 435 to 725 mgCOD/L·d. Besides, the maximum power density achieved in the MFC was 253.84 mW/m2 at the OLR of 435 mgCOD/L·d. Higher OLR may disrupt the recovery of PO43--P and NH4+-N via the MFC. The same pattern was observed for the coulombic efficiency of the MFC and its highest value was 25.01% at the OLR of 435 mgCOD/L·d. It can be concluded that nutrients and electrical power can be simultaneously recovered from municipal wastewater via the dual-chamber MFC.
Ye, Y, Ngo, HH, Guo, W, Chang, SW, Nguyen, DD, Liu, Y, Ni, B-J & Zhang, X 2019, 'Microbial fuel cell for nutrient recovery and electricity generation from municipal wastewater under different ammonium concentrations', Bioresource Technology, vol. 292, pp. 121992-121992.
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© 2019 Elsevier Ltd In the present study, a dual-compartment microbial fuel cell (MFC) was constructed and continuously operated under different influent concentrations of ammonium-nitrogen (5–40 mg/L). The impacts of ammonium on organics removal, energy output and nutrient recovery were investigated. Experimental results demonstrated that this MFC reactor achieved a CDO removal efficiency of greater than 85%. Moreover, excess ammonium concentration in the feed solution compromises the generation of electricity. Simultaneously, the recovery rate of phosphate achieved in the MFC was insignificantly influenced at the wider influent ammonium concentration. In contrast, a high concentration of ammonium may not be beneficial for its recovery.
Ye, Y, Ngo, HH, Guo, W, Liu, Y, Chang, SW, Nguyen, DD, Ren, J, Liu, Y & Zhang, X 2019, 'Feasibility study on a double chamber microbial fuel cell for nutrient recovery from municipal wastewater', Chemical Engineering Journal, vol. 358, pp. 236-242.
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Yeganeh, N & Fatahi, B 2019, 'Effects of choice of soil constitutive model on seismic performance of moment-resisting frames experiencing foundation rocking subjected to near-field earthquakes', Soil Dynamics and Earthquake Engineering, vol. 121, pp. 442-459.
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© 2019 Elsevier Ltd The current study investigated the extent to which the choice of the soil constitutive models can impact the predicted seismic performance of a 20-story reinforced concrete moment-resisting building with a mat foundation considering the Seismic Soil-Structure Interaction (SSSI). Since the soil, in general, is the weakest material, involved in the commonplace geotechnical engineering projects, a soil constitutive model would be able to rule the dynamic response of the system. In this research, the hardening plasticity-based soil constitutive model, named “hyperbolic hardening with hysteretic damping” in conjunction with the two simple, conventional soil models, namely, the isotropic elastic with hysteretic damping model, and elastic-perfectly plastic Mohr-Coulomb with hysteretic damping model, were invoked in the three-dimensional coupled soil-structure numerical simulations using FLAC3D software. The direct method of analysis was used for analyzing the soil-foundation-structure system in one single step without a need to separately analyze each part of the domain. The cherry-picked earthquake excitations, viz, the 1999 Chi-Chi (Taiwan), and 2011 Kohriyama (Japan), were scaled by means of the widely-used response spectrum matching method as per the design response spectrum of a strong rock. The plastic moment concept was employed so as to assign the elastic-perfectly plastic model to the superstructure and its foundation. Additionally, the strain-compatible shear modulus and damping dependency on the cyclic shear strain were considered via the programmed hysteretic damping algorithm. The numerical predictions included the response spectra at the seismic bedrock and ground surface, base shear forces, shear force distributions along the building height, maximum and permanent foundation displacements, and foundation rocking, plus the flooring lateral deflections and inter-story drifts. The life safety limits for the transient and residual total in...
Yetemen, O, Saco, PM & Istanbulluoglu, E 2019, 'Ecohydrology Controls the Geomorphic Response to Climate Change', Geophysical Research Letters, vol. 46, no. 15, pp. 8852-8861.
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AbstractErosion rate data worldwide show complex and contrasting dependencies to climate. Laboratory and numerical model experiments on abiotic landscapes suggest a positive response: Wetter (drier) shift in climate leads to an increase (decrease) in erosion rates with longer relaxation times under a drier climate. We performed eco‐geomorphic landscape evolution model simulations driven by abrupt climate shift in a semiarid climate. With dynamic vegetation, the erosional response to climate shift was opposite to bare soil, variability of erosion rate lessened, and landscape relaxation time scales became insensitive to climate change direction. The spatial geomorphic response to a wetter climate was depositional in vegetated, incisional in barren landscapes, and got reversed with drier climate. A relationship between net erosion rate and mean landscape slope emerged, exhibiting a hysteresis loop. Our study offers insights to the interpretation of observed acceleration of erosion rates and increase mountain relief during Quaternary climate change.
Yip, HL, Fattah, IMR, Yuen, ACY, Yang, W, Medwell, PR, Kook, S, Yeoh, GH & Chan, QN 2019, 'Flame–Wall Interaction Effects on Diesel Post-injection Combustion and Soot Formation Processes', Energy & Fuels, vol. 33, no. 8, pp. 7759-7769.
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Copyright © 2019 American Chemical Society. The aim of this study is to investigate the impact of walls on soot processes of a post-injection strategy at different dwell times. The experiments were performed in an optically accessible constant-volume combustion chamber simulating compression ignition engine conditions with moderate exhaust gas recirculation. The experiments with various injection strategies were performed under ambient conditions with gas density, pressure, and temperature of 20.8 kg/m3, 6 MPa, and 1000 K, respectively, and 15 vol % O2 concentration. The main and post injections had a quantity ratio of 8:2 (main/post) totaling 10 mg, and a flat wall was placed 35 mm axially from the injector. The dwell time between the main and post injections was also varied to induce different levels of interaction between the injections. High-speed flame natural luminosity imaging and two-color pyrometry techniques were applied to observe flame characteristics and to obtain soot temperature and KL factor information, respectively. By comparing the wall jet and free jet cases with no direct jet interaction, it was found that the wall affected the post jet flame structure similarly to a single jet or the main jet. However, the post jet with a greater extent of interaction with the main jet induced by shorter dwell time can achieve better mixing for the wall jet case. Increased interaction between the main and post jets also appeared to induce a soot oxidation phase, which was otherwise not observed when the injections were more temporally separated.
Youssef, AM, Abu Abdullah, MM, Pradhan, B & Gaber, AFD 2019, 'Agriculture Sprawl Assessment Using Multi-Temporal Remote Sensing Images and Its Environmental Impact; Al-Jouf, KSA', Sustainability, vol. 11, no. 15, pp. 4177-4177.
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In this paper, multispectral and multi-temporal satellite data were used to assess the spatial and temporal evolution of the agriculture activities in the Al-Jouf region, Kingdom of Saudi Arabia (KSA). In the current study, an attempt was made to map the agriculture sprawl from 1987 to 2017 using temporal Landsat images in a geographic information system (GIS) environment for better decision-making and sustainable agriculture expansion. Our findings indicated that the agriculture activities developed through two crucial stages: high and low rise stages. Low rise stages occurred during three sub-stages from April 1987 to April 1988, from September 1993 to August 1998, and from April 2008 to May 2015, with overall change rates of 37.9, 44.4, and 30.5 km2/year, respectively. High rise stages occurred during three sub-stages from April 1988 to February 1993, from September 2000 to March 2006, and from April 2016 to August 2017, with overall change rates of 132.4, 159.1, and 119.5 km2/year, respectively. Different environmental problems due to uncontrolled agriculture activities were observed in the area, including substantial depletion of the groundwater table. Another environmental impact observed was the appearance of sinkholes that occurred suddenly with no warning signs. These environmental impacts will increase in the future if no regulated restrictions are implemented by decision-makers.
Yu, C, Wang, H, Wu, Z-X, Sun, W-J & Fatahi, B 2019, 'Analytical Solution for Pollutant Diffusion in Soils with Time-Dependent Dispersion Coefficient', International Journal of Geomechanics, vol. 19, no. 10, pp. 04019109-04019109.
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Yu, Li, Li, Li, Li & Wang 2019, 'Comparative Investigation of Phenomenological Modeling for Hysteresis Responses of Magnetorheological Elastomer Devices', International Journal of Molecular Sciences, vol. 20, no. 13, pp. 3216-3216.
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Magnetorheological elastomer (MRE) is a type of magnetic soft material consisting of ferromagnetic particles embedded in a polymeric matrix. MRE-based devices have characteristics of adjustable stiffness and damping properties, and highly nonlinear and hysteretic force–displacement responses that are dependent on external excitations and applied magnetic fields. To effectively implement the devices in mitigating the hazard vibrations of structures, numerically traceable and computationally efficient models should be firstly developed to accurately present the unique behaviors of MREs, including the typical Payne effect and strain stiffening of rubbers etc. In this study, the up-to-date phenomenological models for describing hysteresis response of MRE devices are experimentally investigated. A prototype of MRE isolator is dynamically tested using a shaking table in the laboratory, and the tests are conducted based on displacement control using harmonic inputs with various loading frequencies, amplitudes and applied current levels. Then, the test results are used to identify the parameters of different phenomenological models for model performance evaluation. The procedure of model identification can be considered as solving a global minimization optimization problem, in which the fitness function is the root mean square error between the experimental data and the model prediction. The genetic algorithm (GA) is employed to solve the optimization problem for optimal model parameters due to its advantages of easy coding and fast convergence. Finally, several evaluation indices are adopted to compare the performances of different models, and the result shows that the improved LuGre friction model outperforms other models and has optimal accuracy in predicting the hysteresis response of the MRE device.
Yu, Y, Chen, X, Gao, W, Wu, D & Castel, A 2019, 'Impact of atmospheric marine environment on cementitious materials', Corrosion Science, vol. 148, pp. 366-378.
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© 2018 Elsevier Ltd This paper presents a novel and comprehensive numerical method to study the impact of the atmospheric marine environment on cementitious materials. The transportations of moisture, aqueous and gaseous substances are modelled by a multi-species transportation model. A hybrid thermodynamic modelling method is developed to consider the chemical interactions, including carbonation, chloride binding, and other simultaneous chemical reactions. The proposed method is implemented to model the reported experiments, and the detailed degradation mechanisms are revealed. Furthermore, the significances of modelling the carbonation-induced water release and the mutual influences between carbonation and chloride aerosol attack are demonstrated.
Yu, Y, Chen, X, Gao, W, Wu, D & Castel, A 2019, 'Modelling non-isothermal chloride ingress in unsaturated cement-based materials', Construction and Building Materials, vol. 217, pp. 441-455.
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© 2019 Elsevier Ltd The realistic environments for engineering practices are diverse, where the temperature, relative humidity, and surface ionic concentrations often experience seasonal variations. The accurate evaluation of the multi-species transportation is crucial in terms of durability assessment of cement-based materials. In this work, an improved moisture transportation model is developed, which takes the influences of the changes in relative humidity, temperature and microstructure into account. The moisture transportation model is coupled with the Poisson-Nernst-Planck model to study the chloride ingress problems. To model the chloride binding effect, both the pre-designed chloride binding isotherm and the thermodynamic modelling method are implemented. In the thermodynamic method, the physical and chemical binding of chloride are modelled in details, and coupled with other simultaneous reactions so as to model the variations of the microstructure. The proposed method is validated against a variety of reported experiments and a long-term field study. The Numerical modelling demonstrates the effectiveness of the improved moisture transportation model and the significance of using the thermodynamic modelling method for long-term durability assessments.
Yu, Y, Dackermann, U, Li, J & Niederleithinger, E 2019, 'Wavelet packet energy–based damage identification of wood utility poles using support vector machine multi-classifier and evidence theory', Structural Health Monitoring, vol. 18, no. 1, pp. 123-142.
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This article presents a novel assessment framework to identify the health condition of wood utility poles. The innovative approach is based on the integration of data mining and machine learning methods and combines advanced signal processing, multi-sensor data fusion and decision ensembles to classify different damage condition types of wood poles. In the proposed framework, wavelet packet analysis is employed to transform captured multi-channel stress wave signals into energy information, which is consequently compressed by principal component analysis to extract a feature vector. Furthermore, support vector machine multi-classifier, optimized by genetic algorithm, is designed to identify the pole condition type. Finally, evidence theory is applied to fuse different assessment results from different sensors for a final decision. For validation of the proposed approach, the wood pole specimens with three common damage condition types are tested using a novel multi-sensor narrow-band frequency-excitation non-destructive testing system in the laboratory. The final experimental analysis results confirm that the proposed approach is capable of making full use of multi-sensor information and providing an effective and accurate identification on types of conditions in wood poles.
Yu, Y, Li, Y, Li, J & Gu, X 2019, 'Characterizing nonlinear oscillation behavior of an MRF variable rotational stiffness device', Smart Structures and Systems, vol. 24, no. 3, pp. 303-317.
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Magneto-rheological fluid (MRF) rotatory dampers are normally used for controlling the constant rotation of machines and engines. In this research, such a device is proposed to act as variable stiffness device to alleviate the rotational oscillation existing in the many engineering applications, such as motor. Under such thought, the main purpose of this work is to characterize the nonlinear torque-angular displacement/angular velocity responses of an MRF based variable stiffness device in oscillatory motion. A rotational hysteresis model, consisting of a rotatory spring, a rotatory viscous damping element and an error function-based hysteresis element, is proposed, which is capable of describing the unique dynamical characteristics of this smart device. To estimate the optimal model parameters, a modified whale optimization algorithm (MWOA) is employed on the captured experimental data of torque, angular displacement and angular velocity under various excitation conditions. In MWOA, a nonlinear algorithm parameter updating mechanism is adopted to replace the traditional linear one, enhancing the global search ability initially and the local search ability at the later stage of the algorithm evolution. Additionally, the immune operation is introduced in the whale individual selection, improving the identification accuracy of solution. Finally, the dynamic testing results are used to validate the performance of the proposed model and the effectiveness of the proposed optimization algorithm.
Yu, Y, Subhani, M, Dackermann, U & Li, J 2019, 'Novel Hybrid Method Based on Advanced Signal Processing and Soft Computing Techniques for Condition Assessment of Timber Utility Poles', Journal of Aerospace Engineering, vol. 32, no. 4, pp. 04019032-04019032.
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© 2019 American Society of Civil Engineers. Recently, a variety of nondestructive evaluation (NDE) approaches have been developed for health assessment and residual capacity estimation of timber structures. Among these methods, guided wave (GW)-based techniques are highly regarded as effective tools for potential use in real situations. Nevertheless, because it is hard to comprehensively grasp the behavior of wave propagation in a wood structure, existing NDE-based techniques mainly depend on an oversimplified hypothesis, which can result in inaccurate or even misleading results in practice. Understanding the complex behavior of GW propagation in wood structures and extracting appropriate information from captured GW signals is a key for successful assessments of in situ conditions of timber structures. This paper analyzes the existing feature extraction and damage detection algorithms, and proposes a novel approach based on an integration of wavelet packet transform (WPT) and ensemble empirical mode decomposition (EEMD) for extracting damage-sensitive patterns, and then a soft computing method like support vector machine (SVM) for pole condition identification. In the proposed method, GW signals measured from a multisensing system with pole health condition as the baseline are divided into a series of subfrequency bands based on WPT. Then EEMD is adopted to extract the intrinsic mode functions (IMFs) that possess the features extracted at corresponding subfrequency bands. Hence, the IMF component was segregated from the original signals of tested poles, and the IMF Shannon entropy was employed to build up the feature vector to effectively demonstrate the health condition. To decrease the size of the feature vector and avoid multiple collinearity among obtained patterns, principal component analysis was employed and entropy information in the feature vector was replaced with main principal components, which will be employed as input variables of the dev...
Yu, Y, Wang, C, Gu, X & Li, J 2019, 'A novel deep learning-based method for damage identification of smart building structures', Structural Health Monitoring, vol. 18, no. 1, pp. 143-163.
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In the past few years, intelligent structural damage identification algorithms based on machine learning techniques have been developed and obtained considerable attentions worldwide, due to the advantages of reliable analysis and high efficiency. However, the performances of existing machine learning–based damage identification methods are heavily dependent on the selected signatures from raw signals. This will cause the fact that the damage identification method, which is the optimal solution for a specific application, may fail to provide the similar performance on other cases. Besides, the feature extraction is a time-consuming task, which may affect the real-time performance in practical applications. To address these problems, this article proposes a novel method based on deep convolutional neural networks to identify and localise damages of building structures equipped with smart control devices. The proposed deep convolutional neural network is capable of automatically extracting high-level features from raw signals or low-level features and optimally selecting the combination of extracted features via a multi-layer fusion to satisfy any damage identification objective. To evaluate the performance of the proposed deep convolutional neural network method, a five-level benchmark building equipped with adaptive smart isolators subjected to the seismic loading is investigated. The result shows that the proposed method has outstanding generalisation capacity and higher identification accuracy than other commonly used machine learning methods. Accordingly, it is deemed as an ideal and effective method for damage identification of smart structures.
Yu, Y, Wu, D, Wang, Q, Chen, X & Gao, W 2019, 'Machine learning aided durability and safety analyses on cementitious composites and structures', International Journal of Mechanical Sciences, vol. 160, pp. 165-181.
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© 2019 The adverse impacts of material deterioration on structural durability and human safety have become increasingly recognised. This paper is concerned with novel metamodeling on the degradation of cementitious composites and structures under environmental attacks. The material deterioration represents a chemophysical process, consisting of the reactive transportations of multiple species. Various coupling effects and associated uncertainties, both material and environmental, may be involved, leading to a complex stochastic system that can only be solved by Monte Carlo simulation. The computational intensiveness calls for advanced methods for uncertainty quantifications. In this paper, an eXtended support vector regression (X-SVR) method is developed to achieve the high-fidelity and efficient stochastic chemophysical modelling. The advanced performance of the proposed method is explored by modelling a laboratory test and a real-life engineering structure.
Yu, Z, Hu, Y, Dzakpasu, M, Wang, XC & Ngo, HH 2019, 'Dynamic membrane bioreactor performance enhancement by powdered activated carbon addition: Evaluation of sludge morphological, aggregative and microbial properties', Journal of Environmental Sciences, vol. 75, pp. 73-83.
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© 2018 The effects of powdered activated carbon (PAC) addition on sludge morphological, aggregative and microbial properties in a dynamic membrane bioreactor (DMBR) were investigated to explore the enhancement mechanism of pollutants removal and filtration performance. Sludge properties were analyzed through various analytical measurements. The results showed that the improved sludge aggregation ability and the evolution of microbial communities affected sludge morphology in PAC-DMBR, as evidenced by the formation of large, regularly shaped and strengthened sludge flocs. The modifications of sludge characteristics promoted the formation process and filtration flux of the dynamic membrane (DM) layer. Additionally, PAC addition did not exert very significant influence on the propagation of eukaryotes (protists and metazoans) and microbial metabolic activity. High-throughput pyrosequencing results indicated that adding PAC improved the bacterial diversity in activated sludge, as PAC addition brought about additional microenvironment in the form of biological PAC (BPAC), which promoted the enrichment of Acinetobacter (13.9%), Comamonas (2.9%), Flavobacterium (0.31%) and Pseudomonas (0.62%), all contributing to sludge flocs formation and several (such as Acinetobacter) capable of biodegrading relatively complex organics. Therefore, PAC addition could favorably modify sludge properties from various aspects and thus enhance the DMBR performance.
Yuan, Z, Dong, L, Gao, Q, Huang, Z, Wang, L, Wang, G & Yu, X 2019, 'SnSb alloy nanoparticles embedded in N-doped porous carbon nanofibers as a high-capacity anode material for lithium-ion batteries', Journal of Alloys and Compounds, vol. 777, pp. 775-783.
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© 2018 SnSb alloy is a promising anode material for lithium-ion batteries due to its high specific capacity. However, the large volume change in the process of charge/discharge causes significant pulverizing of SnSb alloy particles, which leads to a rapid capacity fading. This paper reports the synthesis of homogenous SnSb nanoparticles that are embedded in N-doped porous carbon nanofibers through electrospinning technique with LiN3 serving as poregen agent. This distinctive structure prevents the direct contact of SnSb nanoparticles with the electrolyte and provides enough space for the volume change of SnSb alloy during the Li+ insertion/extraction process, enabling this material to deliver a high reversible capacity of 892 mA h g−1 after 100th cycle at 100 mA g−1, and a stable capacity of 487 mA h g−1 after 1000 cycles at 2000 mA g−1. These results highlight the importance of the synergistic effect of SnSb alloy nanoparticles and N-doped porous carbon nanofibers for the high performance of lithium-ion batteries.
Zhang, G, Li, Y, Wang, H & Wang, J 2019, 'Rheological Properties of Polyurethane-Based Magnetorheological Gels', Frontiers in Materials, vol. 6.
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© 2019 Zhang, Li, Wang and Wang. The paper tests the influence of mass fractions of carbonyl iron particles (CIPs) on the rheological properties of magnetorheological (MR) gels. Polyurethane-based MR gels with different weight fraction of CIPs, i.e., 40, 60, and 80%, were firstly prepared by mechanical mixing, respectively. The changes of shear stress and viscosity with shear rate under different magnetic flux density were tested and analyzed. It was found that the shear stress increases with mass fraction under magnetic flux density. The viscoelastic properties of MRGs were achieved by oscillatory shear measure. The effects of strain amplitude and frequency on viscoelastic of MRGs under different magnetic flux density were measured and analyzed. The study results shown that the elastic characteristics become more obvious with the increase of CIPs mass fraction. However, it has opposite effect on the viscous properties of materials.
Zhang, H, Zhu, X, Li, Z & Yao, S 2019, 'Displacement-dependent nonlinear damping model in steel buildings with bolted joints', Advances in Structural Engineering, vol. 22, no. 5, pp. 1049-1061.
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The stick–slip phenomenon is commonly found at structural connections in steel buildings. It is a major damping mechanism in a structure with bolted joints and makes a significant contribution to the total structural damping. This article reviews the stick–slip damping model of an elastic single-degree-of-freedom system with one stick–slip component. It is observed that the damping ratios of the system with the stick–slip mechanism first quickly increase when experiencing a very small displacement and then slowly decrease. After the number of activated slip surfaces is assumed to be a linear function related to the structural displacement, the equivalent damping ratios of a structural system with numerous stick–slip components are derived. However, this displacement-dependent damping model is very difficult to be used for a structural dynamic analysis due to its inherent complexity. Therefore, a new displacement-dependent damping model for a structural dynamic analysis is proposed based on the viscous damping. A high-rise steel moment resisting frame with bolted joints subjected to an earthquake ground motion is taken as an example to verify the proposed method.
Zhang, L, Ma, C, Liu, L, Pan, J & Wang, Q 2019, 'Fabrication of novel particle electrode γ-Al2O3@ZIF-8 and its application for degradation of Rhodamine B', Water Science and Technology, vol. 80, no. 1, pp. 109-116.
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Abstract Due to the high Brunauer–Emmett–Teller (BET) surface area of zeolitic imidazolate framework (ZIF)-8, a secondary crystallization method was used to prepare a particle electrode of γ-Al2O3@ZIF-8. According to the results from a field emission scanning electron microscope (SEM) and X-ray diffractometer (XRD), the particle electrode of γ-Al2O3 was successfully loaded with ZIF-8, and the BET surface area (1,433 m2/g) of ZIF-8 was over ten times that of γ-Al2O3. The key operation parameters of cell voltage, pH, initial RhB concentration and electrolyte concentration were all optimized. The observed rate constant (kobs) of the pseudo-first-order kinetic model for the electrocatalytic oxidation (ECO) system with the particle electrode of γ-Al2O3@ZIF-8 (15.2 × 10−2 min−1) was over five times higher than that of the system with the traditional particle electrode of γ-Al2O3 (2.6 × 10−2 min−1). The loading of ZIF-8 on the surface of γ-Al2O3 played an important role in improving electrocatalytic activity for the degradation of Rhodamine B (RhB), and the RhB removal efficiency of the three-dimensional (3D) electrocatalytic system with the particle electrode of γ-Al2O3@ZIF-8 was 93.5% in 15 min, compared with 27.5% in 15 min for the particle electrode of γ-Al2O3. The RhB removal efficiency was kept over 85% after five cycles of reuse for the 3D electrocatalytic system with the particle electrode of γ-Al2O3@ZIF-8.
Zhang, L, Pan, J, Liu, L, Song, K & Wang, Q 2019, 'Combined physical and chemical activation of sludge-based adsorbent enhances Cr(Ⅵ) removal from wastewater', Journal of Cleaner Production, vol. 238, pp. 117904-117904.
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© 2019 Elsevier Ltd To enhance the adsorption properties of sludge-based adsorbents (SBAs), the physical activation and the combined physical and chemical activation were examined comparatively. The surface composition and structure of modified SBAs were characterized using BET surface area, XRD and FTIR, the adsorption behavior of modified SBAs was investigated for Cr(Ⅵ) removal from wastewater. For CSU-NaOH, the optimum adsorption time and pH were 0.5 h and 2.5, respectively. The maximum adsorption capacity by CSU-NaOH was 15.3 mg g−1 for Cr(VI) removal, which was over 2 times of those by carbonized sludge and carbonized sludge with urea addition at 25 °C. The adsorption kinetics could be fitted with the pseudo second-order model for three adsorbents, the adsorption isotherm could be fitted with Langmuir model. The thermodynamic analysis indicated that the adsorption process of three adsorbents for Cr(Ⅵ) removal was spontaneous and endothermic. The reusability tests showed that the removal rate of Cr(VI) was kept over 95% by desorbed CSU-NaOH sample until the fifth cycle. The enhancement of adsorption properties can be attributed to both the increase of BET surface area and the improvement of surface functional groups of SBAs. The advantages of higher adsorption capacity and adsorption rate of CSU-NaOH suggest that CSU-NaOH is an effective adsorbent for Cr(Ⅵ) removal.
Zhang, X, Fatahi, B, Khabbaz, H & Poon, B 2019, 'Assessment of the Internal Shaft Friction of Tubular Piles in Jointed Weak Rock Using the Discrete-Element Method', Journal of Performance of Constructed Facilities, vol. 33, no. 6, pp. 04019067-04019067.
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© 2019 American Society of Civil Engineers. This study focuses on the internal shaft friction of open-ended tubular piles induced by jointed weak rock plugs. To investigate the bearing mechanism of the plug, push-up load tests were carried out on the jointed mudstone inside a tubular pile. The discrete-element method (DEM) was used in order to consider heterogeneity and to reproduce the discrete nature of the rock mass. A flat-joint model was used to reproduce the mechanical behavior of mudstone, and a smooth-joint contact model was used to replicate natural joints. The push-up load tests were carried out using the calibrated properties of a weak mudstone. The effects of joint density and joint dip were examined in detail and, as expected, the push-up force of the rock plug was influenced by the joint properties because joint density and joint dip had to some extent affected the plug resistance. The existing joints reduced the push-up force when the joints were steep, whereas the horizontal joints had a minimal effect on altering the inner shaft friction compared with the intact rock mass. The reduced friction along the pile was amplified with joint density, while the exponential increase of vertical stress from the top of the rock plug to the bottom revealed that the inner shaft resistance was mainly mobilized at the bottom portion of the rock plug. The findings of this study increase our understanding of joint dip and joint density affecting the internal shaft resistance of open-ended tubular piles; this knowledge can be used further to develop a design methodology for open-ended tubular piles in weak rock while assessing plugging effects.
Zhang, Y, Liu, Q, He, Z, Zong, Z & Fang, J 2019, 'Dynamic impact response of aluminum honeycombs filled with Expanded Polypropylene foam', Composites Part B: Engineering, vol. 156, pp. 17-27.
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© 2018 The paper investigated the dynamic impact response and characteristics of aluminum honeycomb filled with EPP foam (Expanded polypropylene) experimentally and numerically. It was found that the initial peak strength and mean strength of the filled honeycomb were improved significantly attributable to the interaction effect between the aluminum honeycomb and the foam, but the specific energy absorption (SEA) decreased. For the filled specimens with the same foam density, the initial peak strength, mean strength and SEA increased with the increase in impact velocity. Compared with the characteristics in the static compression test, the initial peak strength in the dynamic impact test increased, whereas the mean strength and SEA decreased. The study showed that EPP foam filling was effective to improve the impact characteristics of the bare aluminum honeycomb. Numerical simulation for the dynamic impact of filled honeycombs was also explored. It accurately reproduced the deformation process and addressed the interaction between the wall and EPP foam. By comparison of the properties in different filling types, it showed the single-cell filling was a good choice to improve the load resistance while using the least filling material.
Zhang, Y, Tehran, K, Scheuermann, A & Li, L 2019, 'Prediction of shrinkage behavior of soft soil using ramp loading consolidation theory', Japanese Geotechnical Society Special Publication, vol. 7, no. 2, pp. 215-218.
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Zhao, H, Tao, M, Li, X, Cao, W & Wu, C 2019, 'Estimation of spalling strength of sandstone under different pre-confining pressure by experiment and numerical simulation', International Journal of Impact Engineering, vol. 133, pp. 103359-103359.
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© 2019 Elsevier Ltd Spalling failure is a common underground engineering disaster, particularly in deep environments with high geo-stress and strong stress disturbances. Therefore, the further investigation of the spalling behaviour of rock under different pre-confining pressures is of considerable importance. In the presented work, a modified split Hopkinson pressure bar (SHPB) system is modified with a pre-confining loading device that can apply pre-static loads to Φ50 mm × 300 mm specimens. The system is employed to study the spalling characteristics of rock specimens subjected to full pre-confining pressure. Spalling tests of Φ50 mm × 300 mm rock specimens under different pre-confining pressures were conducted. The experimental results indicated that spalling failure was influenced by pre-confining pressure. Furthermore, numerical simulations with the same loading conditions as the experiments were conducted using the finite element software, LS-DYNA, and the spalling strengths of the rock specimens under different pre-confining pressures were obtained based on the improved stress wave analysis method. The results indicated that the stress wave analysis method in view of numerical simulation can effectively be used for calculating the spalling strength of rock and rock-like material under pre-confining pressure. The spalling strength of the rock specimens increased first and then decreased as the pre-confining pressure increased.
Zhao, L-S, Zhou, W-H, Geng, X, Yuen, K-V & Fatahi, B 2019, 'A closed-form solution for column-supported embankments with geosynthetic reinforcement', Geotextiles and Geomembranes, vol. 47, no. 3, pp. 389-401.
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© 2019 Elsevier Ltd Soil arching effect results from the non-uniform stiffness in a geosynthetic-reinforced and column-supported embankment system. However, most theoretical models ignore the impact of modulus difference on the calculation of load transfer. In this study, a generalized mathematical model is presented to investigate the soil arching effect, with consideration given to the modulus ratio between columns and the surrounding soil. For simplification, a cylindrical unit cell is drawn to study the deformation compatibility among embankment fills, geosynthetics, columns, and subsoils. A deformed shape function is introduced to describe the relationship between the column and the adjacent soil. The measured data gained from a full-scale test are applied to demonstrate the application of this model. In the parametric study, certain influencing factors, such as column spacing, column length, embankment height, modulus ratio, and tensile strength of geosynthetic reinforcement, are analyzed to investigate the performance of the embankment system. This demonstrates that the inclusion of a geosynthetic reinforcement or enlargement of the modulus ratio can increase the load transfer efficiency. When enhancing the embankment height or applying an additional loading, the height of the load transfer platform tends to be reduced. However, a relatively long column has little impact on the load transfer platform.
Zhao, N, Ngo, HH, Li, Y, Wang, X, Yang, L, Jin, P & Sun, G 2019, 'A comprehensive simulation approach for pollutant bio-transformation in the gravity sewer', Frontiers of Environmental Science & Engineering, vol. 13, no. 4.
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© 2019, Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature. Presently, several activated sludge models (ASMs) have been developed to describe a few biochemical processes. However, the commonly used ASM neither clearly describe the migratory transformation characteristics of fermentation nor depict the relationship between the carbon source and biochemical reactions. In addition, these models also do not describe both ammonification and the integrated metabolic processes in sewage transportation. In view of these limitations, we developed a new and comprehensive model that introduces anaerobic fermentation into the ASM and simulates the process of sulfate reduction, ammonification, hydrolysis, acidogenesis and methanogenesis in a gravity sewer. The model correctly predicts the transformation of organics including proteins, lipids, polysaccharides, etc. The simulation results show that the degradation of organics easily generates acetic acid in the sewer system and the high yield of acetic acid is closely linked to methanogenic metabolism. Moreover, propionic acid is the crucial substrate for sulfate reduction and ammonification tends to be affected by the concentration of amino acids. Our model provides a promising tool for simulating and predicting outcomes in response to variations in wastewater quality in sewers. [Figure not available: see fulltext.]
Zhao, Y, Liu, D, Huang, W, Yang, Y, Ji, M, Nghiem, LD, Trinh, QT & Tran, NH 2019, 'Insights into biofilm carriers for biological wastewater treatment processes: Current state-of-the-art, challenges, and opportunities', Bioresource Technology, vol. 288, pp. 121619-121619.
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Biofilm carriers play an important role in attached growth systems for wastewater treatment processes. This study systematically summarizes the traditional and novel biofilm carriers utilized in biofilm-based wastewater treatment technology. The advantages and disadvantages of traditional biofilm carriers are evaluated and discussed in light of basic property, biocompatibility and applicability. The characteristics, applications performance, and mechanism of novel carriers (including slow-release carriers, hydrophilic/electrophilic modified carriers, magnetic carriers and redox mediator carriers) in wastewater biological treatment were deeply analyzed. Slow release biofilm carriers are used to provide a solid substrate and electron donor for the growth of microorganisms and denitrification for anoxic and/or anaerobic bioreactors. Carriers with hydrophilic/electrophilic modified surface are applied for promoting biofilm formation. Magnetic materials-based carriers are employed to shorten the start-up time of bioreactor. Biofilm carriers acting as redox mediators are used to accelerate biotransformation of recalcitrant pollutants in industrial wastewater.
Zhao, Z, Peng, H, Zhang, X, Zheng, Y, Chen, F, Fang, L & Li, J 2019, 'Identification of lung cancer gene markers through kernel maximum mean discrepancy and information entropy', BMC Medical Genomics, vol. 12, no. S8.
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AbstractBackgroundThe early diagnosis of lung cancer has been a critical problem in clinical practice for a long time and identifying differentially expressed gene as disease marker is a promising solution. However, the most existing gene differential expression analysis (DEA) methods have two main drawbacks: First, these methods are based on fixed statistical hypotheses and not always effective; Second, these methods can not identify a certain expression level boundary when there is no obvious expression level gap between control and experiment groups.MethodsThis paper proposed a novel approach to identify marker genes and gene expression level boundary for lung cancer. By calculating a kernel maximum mean discrepancy, our method can evaluate the expression differences between normal, normal adjacent to tumor (NAT) and tumor samples. For the potential marker genes, the expression level boundaries among different groups are defined with the information entropy method.ResultsCompared with two conventional methods t-test and fold change, the top average ranked genes selected by our method can achieve better performance under all metrics in the 10-fold cross-validation. Then GO and KEGG enrichment analysis are conducted to explore the biological function of the top 100 ranked genes. At last, we choose the top 10 average ranked genes as lung cancer markers and their expression boundaries are calculated and reported.ConclusionThe proposed approach is effective to identify gene markers for lung cancer diagnosis. It is not only more accurate than conventional DEA methods but also provides a reliable method to identify the gene expression level boundaries.
Zheng, K, Liao, Z, Yoda, N, Fang, J, Chen, J, Zhang, Z, Zhong, J, Peck, C, Sasaki, K, Swain, MV & Li, Q 2019, 'Investigation on masticatory muscular functionality following oral reconstruction – An inverse identification approach', Journal of Biomechanics, vol. 90, pp. 1-8.
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© 2019 Elsevier Ltd The human masticatory system has received significant attention in the areas of biomechanics due to its sophisticated co-activation of a group of masticatory muscles which contribute to the fundamental oral functions. However, determination of each muscular force remains fairly challenging in vivo; the conventional data available may be inapplicable to patients who experience major oral interventions such as maxillofacial reconstruction, in which the resultant unsymmetrical anatomical structure invokes a more complex stomatognathic functioning system. Therefore, this study aimed to (1)establish an inverse identification procedure by incorporating the sequential Kriging optimization (SKO)algorithm, coupled with the patient-specific finite element analysis (FEA)in silico and occlusal force measurements at different time points over a course of rehabilitation in vivo; and (2)evaluate muscular functionality for a patient with mandibular reconstruction using a fibula free flap (FFF)procedure. The results from this study proved the hypothesis that the proposed method is of certain statistical advantage of utilizing occlusal force measurements, compared to the traditionally adopted optimality criteria approaches that are basically driven by minimizing the energy consumption of muscle systems engaged. Therefore, it is speculated that mastication may not be optimally controlled, in particular for maxillofacially reconstructed patients. For the abnormal muscular system in the patient with orofacial reconstruction, the study shows that in general, the magnitude of muscle forces fluctuates over the 28-month rehabilitation period regardless of the decreasing trend of the maximum muscular capacity. Such finding implies that the reduction of the masticatory muscle activities on the resection side might lead to non-physiological oral biomechanical responses, which can change the muscular activities for stabilizing the reconstructed mandible.
Zheng, L, Price, WE & Nghiem, LD 2019, 'Effects of fouling on separation performance by forward osmosis: the role of specific organic foulants', Environmental Science and Pollution Research, vol. 26, no. 33, pp. 33758-33769.
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© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. In this study, forward osmosis (FO) membranes and fouling solutions were systematically characterized to elucidate the effects of organic fouling on the rejection of two pharmaceutically active compounds, namely, sulfamethoxazole and carbamazepine. Municipal wastewater resulted in a more severe flux decline compared to humic acid and sodium alginate fouling solutions. This result is consistent with the molecular weight distribution of these foulant solutions. Liquid chromatography with organic carbon detection analysis shows that municipal wastewater consists of mostly low molecular weight acids and neutrals, which produce a more compact cake layer on the membrane surface. By contrast, humic acid and sodium alginate consist of large molecular weight humic substances and biopolymers, respectively. The results also show that membrane fouling can significantly alter the membrane surface charge and hydrophobicity as well as the reverse salt flux. In particular, the reverse salt flux of a fouled membrane was significantly higher than that under clean conditions. Although the rejection of sulfamethoxazole and carbamazepine by FO membrane was high, a discernible impact of fouling on their rejection could still be observed. The results show that size exclusion is a major rejection mechanism of both sulfamethoxazole and carbamazepine. However, they respond to membrane fouling differently. Membrane fouling results in an increase in sulfamethoxazole rejection while carbamazepine rejection decreases due to membrane fouling.
Zheng, M, Duan, H, Dong, Q, Ni, B-J, Hu, S, Liu, Y, Huang, X & Yuan, Z 2019, 'Effects of ultrasonic treatment on the ammonia-oxidizing bacterial (AOB) growth kinetics', Science of The Total Environment, vol. 690, pp. 629-635.
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© 2019 Elsevier B.V. Ultrasound has in the past few decades found applications in a variety of disciplines including chemistry, medicine, physics, and to a much less extent microbiology. Our previous studies found that ultrasonic treatment increases the activity of ammonia-oxidizing bacteria (AOB) while suppressing nitrite-oxidizing bacteria (NOB), resulting in beneficial effects in wastewater treatment. In this study, the kinetic and microbiological features of nitrifying microorganisms in activated sludge intermittently treated with ultrasound were investigated to gain an improved understanding of the mechanism involved in ultrasound-induced stimulation of AOB kinetics. The nitrifying microorganisms were initially enriched over 100 days in a laboratory sequential batch reactor (SBR). Ultrasonic treatment of the sludge was then applied with the treatment time in each 12 h SBR cycle progressively increased from 4 to 24 min. Application of the treatment for 21 days led to a doubled maximum specific ammonia oxidation rate, and also the enhanced dominance of known AOB Nitrosomonas genus in the biomass. This stimulatory effect is well described by a modified enzyme catalyzed reaction model, showing a good linear relationship between the natural logarithm value of μmax,AOB and the applied ultrasonic energy density. This result suggests that ultrasonic treatment likely reduced the activation energy of key enzymes involved in ammonium oxidation.
Zhou, X, Jin, W, Han, S-F, Li, X, Gao, S-H, Chen, C, Xie, G-J, Tu, R, Wang, Q & Wang, Q 2019, 'The mutation of Scenedesmus obliquus grown in municipal wastewater by laser combined with ultraviolet', Korean Journal of Chemical Engineering, vol. 36, no. 6, pp. 880-885.
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© 2019, The Korean Institute of Chemical Engineers. Mutagenetic breeding is an efficient technique for the enhancement of lipid productivity from microalgae. In this study, oil-rich microalga Scenedesmus obliquus were treated by Laser-UV composite mutagenesis. Among the 35 mutant strains, X5 was primely screened. Afterwards, a twice UV mutagenizing was operated on X5, and the optimal mutant strain X5-H13 was obtained. The growth rate, dry weight, lipid yield and lipid content of X5-H13 were 0.698×107 cells/mL·d, 0.99 g/L, 0.49 g/L and 48.8% while cultivated in municipal wastewater, respectively, which were increased by 45%, 58%, 109% and 32% than the original strain. The results of the subculture of repeated mutant showed that the biomass and lipid content of strain X5-H13 were up to 0.99 g/L and 48.8%. The growth of each generation was stable. Furthermore, the random amplified polymorphic DNA analysis indicated that the mutant strain X5-H13 was different from the starting strain, with their genetic similarity coefficient value of 0.815.
Zhou, X, Jin, W, Tu, R, Guo, Q, Han, S-F, Chen, C, Wang, Q, Liu, W, Jensen, PD & Wang, Q 2019, 'Optimization of microwave assisted lipid extraction from microalga Scenedesmus obliquus grown on municipal wastewater', Journal of Cleaner Production, vol. 221, pp. 502-508.
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© 2019 Elsevier Ltd Efficient cost effective lipid extraction from microalgae is a challenging topic for large scale production of microalgae-based biodiesel. In this study, a microwave-assisted lipid extraction process was applied to the oil-rich green microalga Scenedesmus obliquus grown on municipal wastewater. N-hexane/isopropanol solvent was used as alternative solvent. Optimal extraction parameters were determined as: operational temperature of 130 °C, extraction time of 0.25 h, solvent ratio of N-hexane/isopropanol of 3:2 (V:V), phase ratio of co-solvent/biomass was 50:1 (mL:g). Relative extraction rates of lipid and fatty acid methyl esters (FAMEs) achieved using microwave-assisted extraction (MAE) were 88.25% and 95.58%, respectively, which is higher than traditional water bath heating extraction process (WHE). In addition, compared with WHE, the apparent first order rate constant of MAE was enhanced by 18 times compared to traditional methods. Analysis using scanning electron microscopy indicated that disruption of the cell wall of Scenedesmus obliquus by microwave led to the enhancement of solvents’ penetration and lipid extraction.
Zhou, Y, Xu, X, Han, R, Li, L, Feng, Y, Yeerken, S, Song, K & Wang, Q 2019, 'Suspended particles potentially enhance nitrous oxide (N2O) emissions in the oxic estuarine waters of eutrophic lakes: Field and experimental evidence', Environmental Pollution, vol. 252, no. Pt B, pp. 1225-1234.
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© 2019 Elsevier Ltd Estuaries are considered hot spots for the production and emissions of nitrous oxide (N2O) and easily occur suspended particles (SPS), however, current understanding about the role of SPS in the N2O emissions from the oxic estuarine waters of lacustrine ecosystems is still limited. In this study, field investigations were performed in the estuaries of hypereutrophic Taihu Lake, and laboratory simulations were simultaneously conducted to ascertain the characteristics of N2O emissions with different SPS concentrations. The results showed that the N2O emission fluxes ranged from 9.75 to 118.38 μg m−2 h−1, indicating a high spatial heterogeneity for the N2O emissions from the estuaries of Taihu Lake. Although the dissolved oxygen (DO) concentrations were up to 7.85 mg L−1 in the estuarine waters, from where the N2O emissions fluxes were approximately three times that of the lake regions. Multiple regression model selected the total nitrogen (TN), SPS, and DO concentrations as the crucial factors influencing the N2O emission fluxes. Particularly for SPS, the simulation results showed that the N2O concentrations increased gradually with the increase in the SPS concentrations of an oxic water column containing 4 mg L−1 of NO3−-N, indicating that a high SPS concentration can accelerate the N2O emissions. It was related to the change of denitrifying bacteria population in the SPS, as evidenced by its significantly positive correlation with N2O emissions (p < 0.01). Our findings will draw attentions to the role of SPS playing in the N2O productions and emissions in eutrophic lakes, and its effect on nitrogen cycle should be considered in the future study.
Zhu, L-F, Ke, L-L, Zhu, X-Q, Xiang, Y & Wang, Y-S 2019, 'Crack identification of functionally graded beams using continuous wavelet transform', Composite Structures, vol. 210, pp. 473-485.
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© 2018 Elsevier Ltd This paper proposes a new damage index for the crack identification of beams made of functionally graded materials (FGMs) by using the wavelet analysis. The damage index is defined based on the position of the wavelet coefficient modulus maxima in the scale space. The crack is assumed to be an open edge crack and is modeled by a massless rotational spring. It is assumed that the material properties follow exponential distributions along the beam thickness direction. The Timoshenko beam theory is employed to derive the governing equations which are solved analytically to obtain the frequency and mode shape of cracked FGM beams. Then, we apply the continuous wavelet transform (CWT) to the mode shapes of the cracked FGM beams. The locations of the cracks are determined from the sudden changes in the spatial variation of the damage index. An intensity factor, which relates to the size of the crack and the coefficient of the wavelet transform, is employed to estimate the crack depth. The effects of the crack size, the crack location and the Young's modulus ratio on the crack depth detection are investigated.
Zhu, S, Li, JC, Casciati, S & Li, J 2019, 'Special Issue on Smart Devices for Structural Control:Preface', Smart Structures and Systems, vol. 24, no. 1, p. I.
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Zhuang, Y, Zhu, G, Gong, Z, Wang, C & Huang, Y 2019, 'Experimental and numerical investigation of performance of an ethanol-gasoline dual-injection engine', Energy, vol. 186, pp. 115835-115835.
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© 2019 Elsevier Ltd Experiments and simulations were performed to investigate the effect of ethanol direct injection plus gasoline port injection (EDI + GPI) on engine performance. Gasoline direct injection plus GPI (GDI + GPI) was also tested as a reference to EDI + GPI. The experimental results showed that volumetric efficiency increased with the raise of direct injection ratio in both EDI + GPI and GDI + GPI conditions. The volumetric efficiency and IMEP of EDI + GPI were greater than that of GDI + GPI, due to the stronger charge cooling effect of EDI. Combustion process was improved by EDI when ethanol energy ratio (EER) was less than 42%, however further increase of EER led to the deterioration of combustion process. Simulation results showed that ethanol's high laminar flame speed played a dominate role to the improvement of combustion process. Although EDI negatively affected the equivalence ratio around spark plug, this disadvantage was offset by the high laminar flame speed of ethanol, resulting in shorter initial and major combustion durations. Simulation results also found that combustion process was deteriorated when EER was greater than 42%, which was mainly due to over-cooling and poor mixing of EDI. Regarding emissions, NO decreased while CO and HC increased with the raise of both EDI and GDI ratios.
