Abdolali, A, Ngo, HH, Guo, W, Zhou, JL, Zhang, J, Liang, S, Chang, SW, Nguyen, DD & Liu, Y 2017, 'Application of a breakthrough biosorbent for removing heavy metals from synthetic and real wastewaters in a lab-scale continuous fixed-bed column', Bioresource Technology, vol. 229, pp. 78-87.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd A continuous fixed-bed study was carried out utilising a breakthrough biosorbent, specifically multi-metal binding biosorbent (MMBB) for removing cadmium, copper, lead and zinc. The effect of operating conditions, i.e. influent flow rate, metal concentration and bed depth was investigated at pH 5.5 ± 0.1 for a synthetic wastewater sample. Results confirmed that the total amount of metal adsorption declined with increasing influent flow rate and also rose when each metal concentration also increased. The maximum biosorption capacities of 38.25, 63.37, 108.12 and 35.23 mg/g for Cd, Cu, Pb and Zn, respectively, were achieved at 31 cm bed height, 10 mL/min flow rate and 20 mg/L initial concentration. The Thomas model better described the whole dynamic behaviour of the column rather than the Dose Response and Yoon–Nelson models. Finally, desorption studies indicated that metal-loaded biosorbent could be used after three consecutive sorption, desorption and regeneration cycles by applying a semi-simulated real wastewater.
Abdulwahid, WM & Pradhan, B 2017, 'Landslide vulnerability and risk assessment for multi-hazard scenarios using airborne laser scanning data (LiDAR)', Landslides, vol. 14, no. 3, pp. 1057-1076.
View/Download from: Publisher's site
View description>>
Landslide hazard, vulnerability, and risk-zoning maps are considered in the decision-making process that involves land use/land cover (LULC) planning in disaster-prone areas. The accuracy of these analyses is directly related to the quality of spatial data needed and methods employed to obtain such data. In this study, we produced a landslide inventory map that depicts 164 landslide locations using high-resolution airborne laser scanning data. The landslide inventory data were randomly divided into a training dataset: 70 % for training the models and 30 % for validation. In the initial step, a susceptibility map was developed using logistic regression approach in which weights were assigned to every conditioning factor. A high-resolution airborne laser scanning data (LiDAR) was used to derive the landslide conditioning factors for the spatial prediction of landslide hazard areas. The resultant susceptibility was validated using the area under the curve method. The validation result showed 86.22 and 84.87 % success and prediction rates, respectively. In the second stage, a landslide hazard map was produced using precipitation data for 15 years. The precipitation maps were subsequently prepared and show two main categories (two temporal probabilities) for the study area (the average for any day in a year and abnormal intensity recorded in any day for 15 years) and three return periods (15-, 10-, and 5-year periods). Hazard assessment was performed for the entire study area. In the third step, an element at risk map was prepared using LULC, which was considered in the vulnerability assessment. A vulnerability map was derived according to the following criteria: cost, time required for reconstruction, relative risk of landslide, risk to population, and general effect to certain damage. These criteria were applied only on the LULC of the study area because of lack of data on the population and building footprint and types. Finally, risk maps were produced using the de...
Aditya, L, Mahlia, TMI, Rismanchi, B, Ng, HM, Hasan, MH, Metselaar, HSC, Muraza, O & Aditiya, HB 2017, 'A review on insulation materials for energy conservation in buildings', Renewable and Sustainable Energy Reviews, vol. 73, pp. 1352-1365.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd In residential sector, air conditioning system takes the biggest portion of overall energy consumption to fulfil the thermal comfort need. In addressing the issue, thermal insulation is one efficient technology to utilize the energy in providing the desired thermal comfort by its environmentally friendly characteristics. The principle of thermal insulation is by the proper installation of insulation using energy-efficient materials that would reduce the heat loss or heat gain, which leads to reduction of energy cost as the result. This paper is aimed to gather most recent developments on the building thermal insulations and also to discuss about the life-cycle analysis and potential emissions reduction by using proper insulation materials.
Aghdam, IN, Pradhan, B & Panahi, M 2017, 'Landslide susceptibility assessment using a novel hybrid model of statistical bivariate methods (FR and WOE) and adaptive neuro-fuzzy inference system (ANFIS) at southern Zagros Mountains in Iran', Environmental Earth Sciences, vol. 76, no. 6, pp. 1-22.
View/Download from: Publisher's site
View description>>
The aim of landslide susceptibility mapping (LSM) is to produce the most important and basic information required for overall landslide disaster planning and mitigation. Different statistical bivariate methods such as frequency ratio (FR) and weights-of-evidence (WOE) have been widely used for LSM. Although results of these aforementioned statistical methods are generally acceptable, however, they can be improved further by fine tuning the conditioning factor’s classes. The purpose of this paper is to overcome some drawbacks of the bivariate models by developing a novel hybrid method using adaptive neuro-fuzzy inference system (ANFIS) and statistical bivariate methods (FR and WOE) in geographical information system. The provinces of southern Zagros Mountains (Iran) are chosen as a case study to implement the proposed method. First, landslide inventory map was produced using various data source such as historical landslides locations, remote sensing images and land surveying techniques. Second, the inventory data were divided into a ratio 70:30 for training and testing the models. Third, twelve landslide conditioning and triggering factors (such as altitude, slope, aspect, plan and profile curvatures, distance to roads, distance to streams, distance to faults, rainfall, seismicity, land use and lithology) were selected and categorized in two groups consisting of numerical and nominal values. Then, each conditioning factor was classified and the weight of each class was determined by using FR and WOE models. The outputs of individual statistical and hybrid methods were applied to determine nominal and continuous numerical data, respectively. In the hybrid approach, the calculated weights of each class were allocated to the center of each class, and the rest of the weights were determined by ANFIS. Landslide locations which were not used in training the models were used for validation. The produced susceptibility maps were validated and compared using area under the...
Ahmed, MB, Johir, MAH, Zhou, JL, Ngo, HH, Guo, W & Sornalingam, K 2017, 'Photolytic and photocatalytic degradation of organic UV filters in contaminated water', Current Opinion in Green and Sustainable Chemistry, vol. 6, pp. 85-92.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. UV filters as emerging contaminants are of great concern and their wide detection in aquatic environments indicates their chemical stability and persistence. This review summarized the photolytic and photocatalytic degradation of UV filters in contaminated water. The findings indicated that limited research has been conducted on the photolysis and photocatalysis of UV filters. Photolysis of UV filters through UV irradiation in natural water was a slow process, which was accelerated by the presence of photosensitisers e.g. triplet state of chromaphoric dissolved organic matter (3CDOM*) and nutrients but reduced by salinity, dissolved organic matter (DOM) and divalent cations. UV Photocatalysis of 4-methylbenzylidene camphor and 2-phenylbenzimidazole-5-sulfonic acid was very effective with 100% removal within 30 min and 90 min using medicated TiO2/H2O2 and TiO2, respectively. The radiation source, type of catalyst and oxygen content were key factors. Future research should focus on improved understanding of photodegradation pathways and by-products of UV filters.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Johir, MAH & Belhaj, D 2017, 'Competitive sorption affinity of sulfonamides and chloramphenicol antibiotics toward functionalized biochar for water and wastewater treatment', Bioresource Technology, vol. 238, pp. 306-312.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Competitive sorption of sulfamethazine (SMT), sulfamethoxazole (SMX), sulfathiazole (STZ) and chloramphenicol (CP) toward functionalized biochar (fBC) was highly pH dependent with maximum sorption at pH ∼4.0–4.25. Equilibrium data were well represented by the Langmuir and Freundlich models in the order STZ > SMX > CP > SMT. Kinetics data were slightly better fitted by the pseudo second-order model than pseudo first-order and intra-particle-diffusion models. Maximum sorptive interactions occurred at pH 4.0–4.25 through H-bonds formations for neutral sulfonamides species and through negative charge assisted H-bond (CAHB) formation for CP, in addition to π-π electron-donor-acceptor (EDA) interactions. EDA was the main mechanism for the sorption of positive sulfonamides species and CP at pH < 2.0. Sorption of negative sulfonamides species and CP at pH > 7.0 was regulated by H-bond formation and proton exchange with water by forming CAHB, respectively. The results suggested fBC to be highly efficient in removing antibiotics mixture.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Johir, MAH & Sornalingam, K 2017, 'Single and competitive sorption properties and mechanism of functionalized biochar for removing sulfonamide antibiotics from water', Chemical Engineering Journal, vol. 311, pp. 348-358.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Single and competitive sorption of ionisable sulphonamides sulfamethazine, sulfamethoxazole and sulfathiazole on functionalized biochar was highly pH dependent. The equilibrium data were well represented by both Langmuir and Freundlich models for single solutes, and by the Langmuir model for competitive solutes. Sorption capacity and distribution coefficient values decreased as sulfathiazole > sulfamethoxazole > sulfamethazine. The sorption capacity of each antibiotic in competitive mode is about three times lower than in single solute sorption. The kinetics data were best described by the pseudo second-order (PSO) model for single solutes, and by PSO and intra-particle diffusion models for competitive solutes. Adsorption mechanism was governed by pore filling through diffusion process. The findings from pH shift, FTIR spectra and Raman band shift showed that sorption of neutral sulfonamide species occurred mainly due to strong H-bonds followed by π+-π electron-donor-acceptor (EDA), and by Lewis acid-base interaction. Moreover, EDA was the main mechanism for the sorption of positive sulfonamides species. The sorption of negative species was mainly regulated by proton exchange with water forming negative charge assisted H-bond (CAHB), followed by the neutralization of –OH groups by H+released from functionalized biochar surface; in addition π-π electron-acceptor-acceptor (EAA) interaction played an important role.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Johir, MAH, Sornalingam, K & Sahedur Rahman, M 2017, 'Chloramphenicol interaction with functionalized biochar in water: sorptive mechanism, molecular imprinting effect and repeatable application', Science of The Total Environment, vol. 609, pp. 885-895.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Biochar and functionalized biochar (fBC-1 and fBC-2) were prepared and applied to remove antibiotic chloramphenicol from deionized water, lake water and synthetic wastewater. Results showed that chloramphenicol removal on biochar was pH dependent and maximum sorption occurred at pH 4.0–4.5. The sorption data of chloramphenicol fitted better with the Langmuir isotherm model than the Freundlich isotherm model with the maximum Langmuir sorption capacity of 233 μM g− 1 using fBC-2. Chloramphenicol sorption on fBC-2 followed the trend: deionized water > lake water > synthetic wastewater. The presence of humic acid decreased the sorption distribution coefficient (Kd) while the presence of low ionic strength and soil in solution increased Kd value significantly. The mechanism of sorption on fBC mainly involved electron-donor-acceptor (EDA) interactions at pH < 2.0; formation of charge assisted hydrogen bond (CAHB) and hydrogen bonds in addition to EDA in the pH 4.0–4.5; and CAHB and EDA interactions at pH > 7.0. Additionally, solvent and thermal regeneration of fBC-2 for repeatable applications showed excellent sorption of chloramphenicol under the same condition, due to the creation of a molecular imprinting effect in fBC-2. Consequently, fBC-2 can be applied with excellent reusability properties to remove chloramphenicol and other similar organic contaminants.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Johir, MAH, Sornalingam, K, Belhaj, D & Kallel, M 2017, 'Nano-Fe 0 immobilized onto functionalized biochar gaining excellent stability during sorption and reduction of chloramphenicol via transforming to reusable magnetic composite', Chemical Engineering Journal, vol. 322, pp. 571-581.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The widely used nanosized zero-valent iron (nZVI or nFe0) particles and their composite material lose reductive nature during application, and the stability of transformed composite material for repeatable application is not addressed to date. To shed light on this, nZVI was synthesized from scrap material and immobilized on functionalized biochar (fBC) to prepare nZVI-fBC composite. Comparative study between nZVI and nZVI-fBC composite on the removal of chlorinated antibiotic chloramphenicol from different water types was conducted. The results suggested that nZVI was solely responsible for reduction of chloramphenicol. Whereas nZVI-fBC could be applied once, within a few hours, for the reduction of chloramphenico (29–32.5%) and subsequently sorption (67.5–70.5%) by transforming to a fully magnetic composite (nFe3O4-fBC) gaining stability with synergistic sorption performance. In both cases, two reduction by-products were identified namely 2-chloro-N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 257) and dechlorinated N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 223). The complete removal of 3.1 µM L−1 of chloramphenicol in different water was faster by nZVI-fBC (∼12–15 h) than by stable nFe3O4-fBC composite (∼18 h). Both nZVI-fBC and nFe3O4-fBC composites removed chloramphenicol in the order: deionized water > lake water > synthetic wastewater. nFe3O4-fBC showed excellent reusability after regeneration, with the regenerated nFe3O4-fBC composite (after 6 cycles of application) showing significant performance for methylene blue removal (∼287 mg g−1). Therefore, the transformed nFe3O4-fBC composite is a promising and reusable sorbent for the efficient removal of organic contaminants.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Thomaidis, NS & Xu, J 2017, 'Progress in the biological and chemical treatment technologies for emerging contaminant removal from wastewater: A critical review', Journal of Hazardous Materials, vol. 323, pp. 274-298.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. This review focuses on the removal of emerging contaminants (ECs) by biological, chemical and hybrid technologies in effluents from wastewater treatment plants (WWTPs). Results showed that endocrine disruption chemicals (EDCs) were better removed by membrane bioreactor (MBR), activated sludge and aeration processes among different biological processes. Surfactants, EDCs and personal care products (PCPs) can be well removed by activated sludge process. Pesticides and pharmaceuticals showed good removal efficiencies by biological activated carbon. Microalgae treatment processes can remove almost all types of ECs to some extent. Other biological processes were found less effective in ECs removal from wastewater. Chemical oxidation processes such as ozonation/H2O2, UV photolysis/H2O2 and photo-Fenton processes can successfully remove up to 100% of pesticides, beta blockers and pharmaceuticals, while EDCs can be better removed by ozonation and UV photocatalysis. Fenton process was found less effective in the removal of any types of ECs. A hybrid system based on ozonation followed by biological activated carbon was found highly efficient in the removal of pesticides, beta blockers and pharmaceuticals. A hybrid ozonation-ultrasound system can remove up to 100% of many pharmaceuticals. Future research directions to enhance the removal of ECs have been elaborated.
Ajaj, QM, Pradhan, B, Noori, AM & Jebur, MN 2017, 'Spatial Monitoring of Desertification Extent in Western Iraq using Landsat Images and GIS', Land Degradation & Development, vol. 28, no. 8, pp. 2418-2431.
View/Download from: Publisher's site
View description>>
AbstractDesertification refers to land degradation in arid, semi‐arid, and dry sub‐humid areas caused by various factors, including climatic variations and human activities. In recent decades, sandstorms have increased significantly in Western Iraq, which primarily increased desert lands. Proper management is required to control and to monitor the phenomena, as well as to calculate the desertified areas caused by desertification. The study area covered 50,861.854 km2 in Western Iraq. Landsat‐5 TM, Landsat‐7 ETM+, and Landsat‐8 OLI data for 1990, 2002, and 2014 were used. Maximum likelihood algorithm was used to classify the images. Change detection results were discussed in two terms: short‐term (1990–2002) and (2002–2014) and long‐term (1990–2014) analysis. Change detection analysis from 1990 to 2014 showed that desert area increased to 2286.7308 km2, becoming a new source of dust storms. Hazard occurrence probability was studied on September and October 2014. The desertification amount decreased from 1990 to 2002 and increased significantly from 2002 to 2014. Sandstorms have recently been considered a hazardous phenomenon affecting the human population, the vegetation, and the ecosystem in Iraq. Copyright © 2017 John Wiley & Sons, Ltd.
Alanezi, AA & Altaee, A 2017, 'Enhanced Performance Dual Stage Pressure Retarded Osmosis', Energy Procedia, vol. 142, pp. 4182-4197.
View/Download from: Publisher's site
View description>>
© 2017 The Authors. Published by Elsevier Ltd. A dual stage PRO process has been proposed for power generation from a salinity gradient across a semi-permeable membrane. Both closed-loop and open-loop dual stage PRO system were evaluated using 2 M NaCl and Dead Sea as draw solutions, whereas the feed solution was either fresh water or seawater. The impact of feed salinity gradient resource and feed pressure on the net power generation and water flux were evaluated. DSPRO can be combined with desalination plant using seawater brine as the draw solution either in closed-loop or open-loop. This hybridization has multiple applications such as reducing the impact of discharging concentrated brine to sea, energy storage, and increase the recovery rate of the desalination. Power generation by DSPRO will reduce the energy consumption by the desalination processes. Waste heat from power plants can be used for the regeneration of the draw solution in the closed-loop DSPRO. Process modelling has been performed and shown promising results for DSPRO application for power generation.
Altaee, A, Millar, GJ, Zaragoza, G & Sharif, A 2017, 'Energy efficiency of RO and FO–RO system for high-salinity seawater treatment', Clean Technologies and Environmental Policy, vol. 19, no. 1, pp. 77-91.
View/Download from: Publisher's site
View description>>
© 2016, Springer-Verlag Berlin Heidelberg. Forward osmosis (FO) has been proposed as an alternative method for seawater desalination, wherein reverse osmosis (RO) membrane technology is used for regeneration of the draw solution. Previous studies have indicated that a standalone RO unit is more energy efficient than an FO–RO system, and as such it was recommended that an FO–RO system is best employed only for the desalination of high-salinity seawaters. This study examined FO–RO applicability in more detail by examining the impact of seawater salinity, impact of an energy recovery device (ERD), and the effect of membrane fouling. For comparison purposes, the performance of the FO process was improved to minimize the impact of concentration polarization and optimize the concentration of draw solution. Model calculations revealed that FO–RO is more energy efficient than RO when no ERD was employed. However, results showed that there was no significant difference in the power consumption between the FO–RO system and the RO unit at high seawater salinities particularly when a high-efficiency ERD was installed. Moreover, the FO–RO system required more membrane area than a conventional RO unit which may further compromise the FO–RO desalination cost.
Altaee, A, Palenzuela, P, Zaragoza, G & AlAnezi, AA 2017, 'Single and dual stage closed-loop pressure retarded osmosis for power generation: Feasibility and performance', Applied Energy, vol. 191, pp. 328-345.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This work proposes an analysis of conventional (single stage) and dual stage Closed-Loop Pressure Retarded Osmosis (CLPRO) for power generation from a salinity gradient resource. Model calculations were performed taking into account the influence of operating parameters such as the draw solution concentration, membrane area, and draw solution pressure on the performance of the CLPRO process. Modeling results showed that the dual stage CLPRO process outperformed the conventional CLPRO process and power generation increased 18% by adding a second stage of PRO membrane. Multi-Effect Distillation (MED) was selected for the regeneration of the draw solution taking advantage of an available source of waste heat energy. The performance of MED process has been assessed by investigating two key parameters: the specific thermal consumption and the specific heat transfer area. The model calculations showed that the power generation by the single and dual stage CLPRO was higher than the electrical power consumption by the MED plant. In the case of the power generation obtained by the dual stage CLPRO, it was 95% higher than the electrical power consumption by the MED plant, proving the possibility of using low-grade heat for producing electricity from a salinity gradient resource.
Altaee, A, Zaragoza, G, Drioli, E & Zhou, J 2017, 'Evaluation the potential and energy efficiency of dual stage pressure retarded osmosis process', Applied Energy, vol. 199, pp. 359-369.
View/Download from: Publisher's site
View description>>
© 2017 Power generation by means of Pressure Retarded Osmosis (PRO) has been proposed for harvesting the energy of a salinity gradient. Energy recovery by the PRO process decreases along the membrane module due to depleting of the chemical potential across the membrane and concentration polarization effects. A dual stage PRO (DSPRO) design can be used to rejuvenate the chemical potential difference and reduce the concentration polarization on feed solution. Several design configurations were suggested for the membrane module arrangements in the first and second stage of the PRO process. PRO performance was evaluated for a number of salinity gradients proposed by coupling Dead Sea water or Reverse Osmosis (RO) brine with seawater or wastewater effluent. Maximum specific energy of inlet and outlet feeds was calculated using a developed computer model to identify the amount of recovered and remaining energy. Initially, specific power generation by the PRO process increased by increasing the number of modules of the first stage. Maximum specific energy is calculated along the PRO module to understand the degradation of the maximum specific energy in each module before introducing a second stage PRO process. Adding a second stage PRO process resulted in a sharp increase of the chemical potential difference and the specific energy yield of the process. Between 10% and 13% increase of the specific power generation was achieved by the DSPRO process for the Dead Sea-seawater salinity gradient depending on the dual stage design configuration. For Dead Sea-RO brine, 12–16% increase of the specific power generation was achieved by the dual stage PRO process. For Dead Sea-wastewater and RO brine-wastewater, a neutral and sometimes negative impact occurred when a second stage PRO process was introduced. We concluded that, for a given draw solution concentration, dual stage performs better than the conventional PRO process at high feed salinities, yet requires lower h...
Altaee, A, Zhou, J, Alhathal Alanezi, A & Zaragoza, G 2017, 'Pressure retarded osmosis process for power generation: Feasibility, energy balance and controlling parameters', Applied Energy, vol. 206, pp. 303-311.
View/Download from: Publisher's site
View description>>
© 2017 The feasibility of pressure-retarded osmosis (PRO) for power generation was evaluated with consideration of the energy inputs and losses in the process. The effects of the concentration polarization, reverse salt diffusion, and external resistance at the membrane porous layer were quantified, for the first time, along the membrane module to determine their contributions to the energy loss in the PRO process. Concentration polarization was responsible for up to 40% of the energy loss during the PRO process. However, increasing the PRO membrane modules from 1 to 4 resulted in a variable increase of the energy output depending on the salinity gradient. The energy requirements for draw and feed solution pretreatment were estimated to be over 38% of the total energy inputs. Results showed that coupling seawater (SW) with river water (RW) was unable to generate sufficient energy to compensate for the energy inputs and losses during the PRO process. With 0.39 kwh/m3 maximum specific energy in the PRO process, the energy yield of reverse osmosis brine (ROB)-wastewater (WW) salinity gradient was slightly greater than the total energy inputs, although using Dead Sea-SW/ROB salinity gradient was more promising. Overall, the primary current limitation is the lack of suitable PRO membranes that can withstand a high hydraulic pressure.
Althuwaynee, OF & Pradhan, B 2017, 'Semi-quantitative landslide risk assessment using GIS-based exposure analysis in Kuala Lumpur City', Geomatics, Natural Hazards and Risk, vol. 8, no. 2, pp. 706-732.
View/Download from: Publisher's site
Amin, M, Putra, N, Kosasih, EA, Prawiro, E, Luanto, RA & Mahlia, TMI 2017, 'Thermal properties of beeswax/graphene phase change material as energy storage for building applications', Applied Thermal Engineering, vol. 112, pp. 273-280.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd Increased energy consumption in buildings is a worldwide issue. This research is concerned with the implementation of a phase change material for thermal storage. This concept has gained great attention as a solution to reduce energy consumption in buildings. Beeswax, which is a phase change material with a high thermal capacity, is investigated in this research. This paper is intended to measure and analyze the thermal properties of beeswax/graphene as a phase change material. The melting temperature, thermal capacity and latent heat were determined using differential scanning calorimetry (DSC), and the thermal conductivity was investigated using a thermal conductivity measurement apparatus. To discover the change in the physical properties due to the effect of nanoparticles, the viscosity of the material was investigated as well. Based on the result from the DSC, the latent heat of 0.3 wt% beeswax/graphene increased by 22.5%. The thermal conductivity of 0.3 wt% beeswax/graphene was 2.8 W/m K. The existence of graphene nanoplatelets enhanced both the latent heat and thermal conductivity of the beeswax. Therefore, based on this result, beeswax/graphene is concluded to have the potential to reduce energy consumption in buildings.
Amini, Z, Ilham, Z, Ong, HC, Mazaheri, H & Chen, W-H 2017, 'State of the art and prospective of lipase-catalyzed transesterification reaction for biodiesel production', Energy Conversion and Management, vol. 141, pp. 339-353.
View/Download from: Publisher's site
Amini, Z, Ong, HC, Harrison, MD, Kusumo, F, Mazaheri, H & Ilham, Z 2017, 'Biodiesel production by lipase-catalyzed transesterification of Ocimum basilicum L. (sweet basil) seed oil', Energy Conversion and Management, vol. 132, pp. 82-90.
View/Download from: Publisher's site
Ansari, AJ, Hai, FI, Price, WE, Drewes, JE & Nghiem, LD 2017, 'Forward osmosis as a platform for resource recovery from municipal wastewater - A critical assessment of the literature', Journal of Membrane Science, vol. 529, pp. 195-206.
View/Download from: Publisher's site
View description>>
© 2017 Forward osmosis (FO) is an emerging membrane separation technology that has the potential to serve as a game changer in wastewater treatment. FO-based processes can simultaneously produce high quality effluent and pre-concentrated wastewater for anaerobic treatment to facilitate the recovery of energy and nutrients. Complex wastewaters can be directly pre-treated by FO and fresh water can be produced when coupled with a draw solute recovery process (i.e. reverse osmosis or membrane distillation). By enriching organic carbon and nutrients for subsequent biogas production, FO extends the resource recovery potential of current wastewater treatment processes. Here, we critically review recent applications of FO for simultaneous treatment and resource recovery from municipal wastewater. Research conducted to date highlights the importance of successfully integrating FO with anaerobic treatment. Emphasis is also placed on the development of novel FO-based hybrid systems utilising alternative energy sources for draw solute recovery. There remain several technical challenges to the practical realisation of FO for resource recovery from wastewater including salinity build-up, membrane fouling, and system scale-up. Strategies to overcome these challenges are critically assessed to establish a research roadmap for further development of FO as a platform for resource recovery from wastewater.
Arslan, A, Masjuki, HH, Kalam, MA, Varman, M, Mosarof, MH, Mufti, RA, Quazi, MM, Khuong, LS, Liaqat, M, Jamshaid, M, Alabdulkarem, A & Khurram, M 2017, 'Investigation of laser texture density and diameter on the tribological behavior of hydrogenated DLC coating with line contact configuration', Surface and Coatings Technology, vol. 322, pp. 31-37.
View/Download from: Publisher's site
Asikin-Mijan, N, Lee, HV, Taufiq-Yap, YH, Abdulkrem-Alsultan, G, Mastuli, MS & Ong, HC 2017, 'Optimization study of SiO 2 -Al 2 O 3 supported bifunctional acid–base NiO-CaO for renewable fuel production using response surface methodology', Energy Conversion and Management, vol. 141, pp. 325-338.
View/Download from: Publisher's site
Askari, M, Li, J & Samali, B 2017, 'Cost-effective multi-objective optimal positioning of magnetorheological dampers and active actuators in large nonlinear structures', Journal of Intelligent Material Systems and Structures, vol. 28, no. 2, pp. 230-253.
View/Download from: Publisher's site
View description>>
The optimal number and location of control devices not only play a major role in an effective structural control system but also lead to a cost-effective design. This article presents a multi-objective optimization method based on a new genetic algorithm for simultaneous finding of the optimal number and placement of actuators and magnetorheological dampers, in active and semi-active vibration control of structures. The proposed strategy considers three objective functions to be minimized through optimization, including peak inter-storey drift ratio, peak acceleration and peak base shear force to make sure both human comfort and safety of the structure are guaranteed. Also, by choosing a pre-defined level of performance on dynamic responses of a structure, the designer can decide on decreasing or increasing the number of control devices in a systematic way and minimize the control cost. The approach is then validated through a nonlinear 20-storey benchmark problem. The results from active control system show how a problem that was initially solved with 25 actuators can be solved with less than a quarter of those actuators, having similar results in terms of aforementioned indices. The optimal distribution of different numbers of magnetorheological dampers in the same benchmark building is also studied in this article and compared to those obtained from actuators. Due to highly nonlinear behaviour of these devices, and also the complexity of the under-study benchmark structure, few reported researches have been conducted in this area. Also, the comparison between optimal places of active and semi-active control devices in the same structure has hitherto not been reported in the open literature.
Awadallah, M, Tawadros, P, Walker, P & Zhang, N 2017, 'Dynamic modelling and simulation of a manual transmission based mild hybrid vehicle', Mechanism and Machine Theory, vol. 112, pp. 218-239.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This paper investigates the development of a mild hybrid powertrain system through the integration of a conventional manual transmission equipped powertrain and a secondary power source in the form of an electric motor driving the transmission output shaft. The primary goal of this paper is to study the performance of partial power-on gear shifts through the implementation of torque hole filling by the electric motor during gear changes. To achieve this goal, mathematical models of both conventional and mild hybrid powertrain are developed and used to compare the system dynamic performance of the two systems. This mathematical modelling is used to run different simulations for gear-shift control algorithm design during system development, allowing us to evaluate the achievable performance and its dependency on system properties. The impact of motor power on the degree of torque hole compensation is also investigated, keeping in mind the practical limits to motor specification. This investigation uses both the output torque, vehicle speed as well as vibration dose value to evaluate the quality of gearshifts at different motor sizes. Results demonstrate that the torque hole may be eliminated using a motor power of 50 kW. However, the minimum vibration dose value during gear change is achieved using a peak power of 16–20 kW.
Awadallah, M, Tawadros, P, Walker, P & Zhang, N 2017, 'Impact of Low and High Congestion Traffic Patterns on a Mild-HEV Performance', SAE Technical Paper Series, vol. 2017-October.
View/Download from: Publisher's site
View description>>
Copyright © 2017 SAE International. Driven by stricter mandatory regulations on fuel economy improvement and emissions reduction, market penetration of electrified vehicles will increase in the next ten years. Within this growth, mild hybrid vehicles will become a leading sector. The high cost of hybrid electric vehicles (HEV) has somewhat limited their widespread adoption, especially in developing countries. Conversely, it is these countries that would benefit most from the environmental benefits of HEV technology. Compared to a full hybrid, plug-in hybrid, or electric vehicle, a mild hybrid system stands out due to its maximum benefit/cost ratio. As part of our ongoing project to develop a mild hybrid system for developing markets, we have previously investigated improvements in drive performance and efficiency using optimal gearshift strategies, as well as the incorporation of high power density supercapacitors. In this paper, the fuel and emissions of a baseline conventional vehicle and mild hybrid electric vehicle (MHEV) are compared. The objective of this analysis is to compare the fuel economy and Greenhouse Gas (GHG) emissions of the baseline and MHEV models, using low and high-density traffic patterns chosen for their similarity to traffic density profiles of our target markets. Results demonstrate the benefits of a lower ongoing cost for the HEV architecture. These advantages include torque-hole filling between gear changes, increased fuel efficiency and performance.
Banihashemi, S, Ding, G & Wang, J 2017, 'Developing a Hybrid Model of Prediction and Classification Algorithms for Building Energy Consumption', Energy Procedia, vol. 110, pp. 371-376.
View/Download from: Publisher's site
View description>>
© 2017 The Authors. Artificial intelligence algorithms have been applied separately or integrally for prediction, classification or optimization of buildings energy consumption. However, there is a salient gap in the literature on the investigation of hybrid objective function development for energy optimization problems including qualitative and quantitative datasets in their constructs. To tackle with this challenge, this paper presents a hybrid objective function of machine learning algorithms in optimizing energy consumption of residential buildings through considering both continuous and discrete parameters of energy simultaneously. To do this, a comprehensive dataset including significant parameters of building envelop, building design layout and HVAC was established, Artificial Neural Network as a prediction and Decision Tree as a classification algorithm were employed via cross-training ensemble equation to create the hybrid function and the model was finally validated via the weighted average of the error decomposed for the performance. The developed model could effectively enhance the accuracy of the objective functions used in the building energy prediction and optimization problems. Furthermore, the results of this novel approach resolved the inclusion issue of both continuous and discrete parameters of energy in a unified objective function without threatening the integrity and consistency of the building energy datasets.
Barua, P, Rahman, SH & Molla, MH 2017, 'Sustainable adaptation for resolving climate displacement issues of south eastern islands in Bangladesh', International Journal of Climate Change Strategies and Management, vol. 9, no. 6, pp. 790-810.
View/Download from: Publisher's site
View description>>
PurposeClimate change is affecting people displacement in Bangladesh by both sudden environmental events and gradual environmental change. This paper aims to assess the sustainable adaptation measures for resolving the displacement problem induced by climate change considering the socioeconomic differences between the past and the present location of living places for island dwellers of the south-eastern coast of Bangladesh.Design/methodology/approachBoth qualitative and quantitative approaches were adopted for conducting the study. The main tool of the household survey was a questionnaire survey. In addition to the estimate of displacement, the authors have used hazard impact analysis, weightage analysis and sustainable adaptation analysis with various ranking. Meaningful data were analyzed through SPSS software and presented through statistical techniques.FindingsClimate change-induced different natural disasters, such as cyclone, tidal surge, tidal flood and coastal erosion, were frequent in the study areas and responsible for mass displacement. After displacement, people lost not only their identity but also social and cultural harmony and faced different economic and environmental crises. However, nearly 20 types of adaptation options were identified for protection from the displacement of coastal people.Practical implicationsThe study prescribed 11 specific criteria and 4 principles of sustainable adaptation options for resolving the climate displacement problem. Moreover, seven adaptation practices showed high sustainability, ten showed medium sustainability and five ...
Basack, S & Nimbalkar, S 2017, 'Free strain analysis of the performance of vertical drains for soft soil improvement', Geomechanics and Engineering, vol. 13, no. 6, pp. 963-975.
View/Download from: Publisher's site
View description>>
Improvement of soft clay deposit by preloading with vertical drains is one of the most popular techniques followed worldwide. These drains accelerate the rate of consolidation by shortening the drainage path. Although the analytical and numerical solutions available are mostly based on equal strain hypothesis, the adoption of free strain analysis is more realistic because of the flexible nature of the imposed surcharge loading, especially for the embankment loading used for transport infrastructure. In this paper, a numerical model has been developed based on free strain hypothesis for understanding the behaviour of soft ground improvement by vertical drain with preloading. The unit cell analogy is used and the effect of smear has been incorporated. The model has been validated by comparing with available field test results and thereafter, a hypothetical case study is done using the available field data for soft clay deposit existing in the eastern part of Australia and important conclusions are drawn therefrom.
Basack, S & Nimbalkar, S 2017, 'Numerical Solution of Single Pile Subjected to Torsional Cyclic Load', International Journal of Geomechanics, vol. 17, no. 8, pp. 04017016-04017016.
View/Download from: Publisher's site
View description>>
© 2017 American Society of Civil Engineers. Large structures, such as offshore platforms, wind turbine foundations, wide buildings, bridges, and railway granular embankments, are often supported by pile foundations. These structures are usually subjected to large cyclic loads (in axial, lateral, and torsional modes) arising from actions of waves, ship impacts, or moving trains. Significant torsional cyclic forces can be transferred to the foundation piles due to the eccentricity of the lateral loads. In the past, several theoretical and experimental investigations were carried out on piles under axial and lateral cyclic loads; however, study of the influence of torsional cyclic loads on pile foundations is rather limited. This paper presents a novel numerical model based on the boundary element approach to analyze the response of a single, vertical, floating pile subjected to torsional cyclic load. The nonlinear stress-strain response of soil is incorporated, and the pile material was idealized as elastic-perfectly plastic. The effect of progressive degradation of soil strength and stiffness under cyclic stress reversal is incorporated in the numerical method. Apart from predicting the degradation of torsional pile-soil interactive performance, the profiles for shear stress and angle of twist are also captured by the proposed solution. Validation of the model indicates the suitability and accuracy of the proposed solutions. The frequency, amplitude, and number of cycles play significant roles in torsional cyclic response of piles. The proposed model is also applied successfully to selected case studies on single piles under torsional cyclic loading, and important conclusions are drawn from there.
Basack, S, Indraratna, B, Rujikiatkamjorn, C & Siahaan, F 2017, 'Modeling the Stone Column Behavior in Soft Ground with Special Emphasis on Lateral Deformation', Journal of Geotechnical and Geoenvironmental Engineering, vol. 143, no. 6, pp. 04017016-04017016.
View/Download from: Publisher's site
Bathrellos, GD, Skilodimou, HD, Chousianitis, K, Youssef, AM & Pradhan, B 2017, 'Suitability estimation for urban development using multi-hazard assessment map', Science of The Total Environment, vol. 575, pp. 119-134.
View/Download from: Publisher's site
View description>>
© 2016 Preparation of natural hazards maps are vital and essential for urban development. The main scope of this study is to synthesize natural hazard maps in a single multi-hazard map and thus to identify suitable areas for the urban development. The study area is the drainage basin of Xerias stream (Northeastern Peloponnesus, Greece) that has frequently suffered damages from landslides, floods and earthquakes. Landslide, flood and seismic hazard assessment maps were separately generated and further combined by applying the Analytical Hierarchy Process (AHP) and utilizing a Geographical Information System (GIS) to produce a multi-hazard map. This map represents the potential suitability map for urban development in the study area and was evaluated by means of uncertainty analysis. The outcome revealed that the most suitable areas are distributed in the southern part of the study area, where the landslide, flood and seismic hazards are at low and very low level. The uncertainty analysis shows small differences on the spatial distribution of the suitability zones. The produced suitability map for urban development proves a satisfactory agreement between the suitability zones and the landslide and flood phenomena that have affected the study area. Finally, 40% of the existing urban pattern boundaries and 60% of the current road network are located within the limits of low and very low suitability zones.
Bayat, E, Rodríguez, JF, Saco, PM, de Almeida, GAM, Vahidi, E & García, MH 2017, 'A tale of two riffles: Using multidimensional, multifractional, time‐varying sediment transport to assess self‐maintenance in pool‐riffle sequences', Water Resources Research, vol. 53, no. 3, pp. 2095-2113.
View/Download from: Publisher's site
View description>>
AbstractPool‐riffle sequences play a central role in providing habitat diversity conditions both in terms of flow and substrate in gravel bed streams. Understanding their capacity to self‐maintain has been the focus of research for many years, starting with the velocity reversal hypothesis. This hypothesis relied only on cross sectional averaged flow information, but its limited success prompted extensions of the hypothesis and alternative explanations for self‐maintenance. Significant advances beyond the velocity reversal hypothesis have been achieved by incorporating more information either on flow or sediment transport characteristics. However, this has been done in a compartmentalized way, with studies either focusing on one or the other aspect. This work bridges the gap between these two aspects by using an approximate methodology that combines observed characteristic stage‐dependent 3‐D flow patterns with time‐varying cross sectional information on bed shear stresses, sediment distribution, and sediment bed changes during a 1 year record of continuous discharges from a real stream. This methodology allows us to track the behavior of different sediment size fractions along flow streamlines over time and identify self‐maintenance conditions due to the combined effect of both flow multidimensionality and sediment transport. We apply this approximate methodology to two contiguous pools and riffles and demonstrate that, unexpectedly, they may rely on different mechanisms for self‐maintenance due to differences in geometry and sediment size distribution. We also demonstrate that our methodology is potentially overarching and integrative of previous partial approaches based on flow multidimensionality or sediment transport, which tend to underestimate the occurrence of self‐maintenance.
Belhaj, D, Athmouni, K, Frikha, D, Kallel, M, El Feki, A, Maalej, S, Zhou, JL & Ayadi, H 2017, 'Biochemical and physiological responses of halophilic nanophytoplankton (Dunaliella salina) from exposure to xeno-estrogen 17α-ethinylestradiol', Environmental Science and Pollution Research, vol. 24, no. 8, pp. 7392-7402.
View/Download from: Publisher's site
View description>>
© 2017, Springer-Verlag Berlin Heidelberg. The environmental impacts of various pollutants on the entire levels of organisms are under investigation. Among these pollutants, endocrine-disrupting compounds (EDCs) present a serious hazard, even though the environmental significance of these compounds remains basically unknown. To drop some light on this field, we assessed the effects of a 11-day exposure of 17α-ethinylestradiol (EE2) on the growth, metabolic content, antioxidant response, oxidative stress, and genetic damage of Dunaliella salina, isolated from Tunisian biotopes. The results showed that at 10 ng L−1, EE2 could stimulate the growth of D. salina and increase its cellular content of photosynthetic pigments and metabolites; however, it did not significantly increase the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) or the level of malondialdehyde (MDA) and hydrogen peroxide (H2O2). In contrast, exposure to high levels of EE2 concentrations significantly inhibited the growth of D. salina (P < 0.05), decreased the cellular content of photosynthetic pigments, increased the cellular content of all of the metabolites and the SOD activity, and inhibited CAT and GPx activities. Nevertheless, the balance between oxidant and antioxidant enzymes was disrupted because H2O2 content along with MDA content simultaneously increased. Contrary to expected results, DNA damage (strand breaks) decreased after the exposure of algae to EE2. The results of this study suggest that EE2 toxicity could result in environmental impacts with consequences on the whole aquatic community. [Figure not available: see fulltext.]
Belhaj, D, Frikha, D, Athmouni, K, Jerbi, B, Ahmed, MB, Bouallagui, Z, Kallel, M, Maalej, S, Zhou, J & Ayadi, H 2017, 'Box-Behnken design for extraction optimization of crude polysaccharides from Tunisian Phormidium versicolor cyanobacteria (NCC 466): Partial characterization, in vitro antioxidant and antimicrobial activities', International Journal of Biological Macromolecules, vol. 105, pp. 1501-1510.
View/Download from: Publisher's site
View description>>
© 2017 In this study, response surface methodology (RSM) based on Box-Behnken design (BBD) was employed to optimize the aqueous extraction of crude polysaccharides from Tunisian cyanobacteria Phormidium versicolor (NCC 466). The optimal extraction conditions with an extraction yield of 21.56 ± 0.92% were as follows: extraction temperature at 81.05 °C, extraction time of 3.99 h, and water to raw material ratio of 21.52 mL g−1. Crude Phormidium versicolor polysaccharides (CPv-PS) are found to be a hetero-sulfated-anionic polysaccharides that contained carbohydrate (79.37 ± 1.58%), protein (0.45 ± 0.11%), uronic acids (4.37 ± 0.19%) and sulfate (6.83 ± 0.28%). The carbohydrate fraction was composed of arabinose, xylose, ribose, rhamnose, N-acetyl glucosamine, galactose, glucose, mannose, glucuronic acid and saccharose with corresponding mole percentages of 2.41, 14.58, 2.18, 6.23, 7.04, 28.21, 26.04, 3.02, 0.86 and 5.07, respectively. Evaluation of the antioxidant activity in vitro suggested that CPv-PS strongly scavenged radicals, prevented bleaching of β-carotene and reduced activity. Furthermore, the CPv-PS exhibited effective antimicrobial properties.
Bishop, D, Situ, R, Brown, R & Surawski, N 2017, 'Numerical Modelling of Biodiesel Blends in a Diesel Engine', Energy Procedia, vol. 110, pp. 402-407.
View/Download from: Publisher's site
View description>>
© 2017 The Authors. Biodiesel is a biofuel which has similar properties to diesel and can readily be used in a diesel engine with minimal modifications. Promising results have been determined using mixtures of biodiesel and diesel with the reduction of soot and emissions of a diesel engine. Experimental analysis of diesel engines can be expensive and therefore Computation Fluid Dynamics programs are used to analyses the combustion process. The AVL Fire ESED program is currently being employed to investigate the effects of biodiesel on the diesel engines soot, emissions and power generation from a Cummins ISBE220 engine. Investigation is performed on pre and post injection-rate shapes on the combustion process establishing the results correlate accurately with researched data. A pre injection was determined to increase maximum power, reduce combustion generated noise, increase early in cylinder temperature and reduce fuel consumption due to the increase in power. A post injection was verified to reduce soot emissions while increasing NOx emissions marginally. The investigation of the injection-rate shape established the soot-NOx trade-off which was also found in the research. The models developed were agreeable with biodiesel data with percentage error in indicated power ranging from 1.62-8.85%. The models suggested that biodiesel assists in reducing NOx and soot emissions. The soot-NOx trade-off was further investigated determining the theory that then by reducing the combustion temperature in the combustion chamber the NOx emissions can be reduced while increasing soot emissions. By increasing the temperature in the combustion chamber the opposite effect was found to occur.
Booth, N, Davidson, G, Imperia, P, Lee, S, Stuart, B, Thomas, P, Komatsu, K, Yamane, R, Prescott, SW, Maynard-Casely, HE, Nelson, A & Rule, KC 2017, 'Three impossible things before lunch – the task of a sample environment specialist', Journal of Neutron Research, vol. 19, no. 1-2, pp. 49-56.
View/Download from: Publisher's site
View description>>
© 2017 - IOS Press and the authors. All rights reserved. In the course of their day, sample environment professionals can be confronted by numerous technical challenges applicable to a range of scientific questions. This paper presents three successful outcomes from user-posed sample environment challenges for in situ neutron scattering experiments undertaken at the Australian Centre for Neutron Scattering (formerly the Bragg Institute). The sample environments presented here have nothing in common other than their novelty. They may not be the best solution but have been constrained by time, resources and ability. The questions the users posed were: Can we mount a cylinder in cylinder (CIC) rheometer, more regularly used on a small angle scattering instrument, on a diffraction instrument and obtain usable data? Can we supply high-voltage (up to 10 kV) across a sample within the Paris-Edinburgh press while mounted on a powder diffraction instrument? And finally can a Lakeshore 340 and an in-house built liquid conductivity cell do the job of a commercial liquid conductivity meter? This paper presents the engineering and equipment solutions that were used to answer these questions, and in each case the scientific users left with useful, intriguing and, hopefully, publishable data.
Burton, GJ, Pineda, JA, Sheng, D, Airey, DW, Zhang, F, Rawat, A, Al-Badran, YM & Schanz, T 2017, 'Exploring one-dimensional compression of compacted clay under constant degree of saturation paths', Géotechnique, vol. 67, no. 1, pp. 86-90.
View/Download from: Publisher's site
Cai, Q, Turner, BD, Sheng, D & Sloan, S 2017, 'Impact of Barium and Cadmium on Defluoridation by Calcite: Batch Reactor and Column Tests', Environmental Engineering Science, vol. 34, no. 11, pp. 792-804.
View/Download from: Publisher's site
Cai, Y, Chen, Q, Zhou, Y, Nimbalkar, S & Yu, J 2017, 'Estimation of Passive Earth Pressure against Rigid Retaining Wall Considering Arching Effect in Cohesive-Frictional Backfill under Translation Mode', International Journal of Geomechanics, vol. 17, no. 4, pp. 04016093-04016093.
View/Download from: Publisher's site
View description>>
n this study, a novel analytical approach is proposed to calculate the passive earth pressure against a rigid retaining wall subjected to the translation mode. Effects of arching in cohesive backfill soils as well as friction mobilized along the wall–soil interface are considered. Analytical expressions of the earth pressure, passive resistance, and its height of application on the backface of the retaining wall were derived based on static equilibrium of forces under passive conditions acting on the failure wedge. A parametric study was undertaken to assess effects of internal friction angle of backfill, wall–soil interface friction angle, surcharge pressure, cohesion, unit weight, and inclination angle of the slip surface on the active earth pressure as well as on the slip-surface angle. The results of the proposed method were then verified against the existing test data as well as the predictions by Coulomb theory and Rankine theory. The results show that the proposed method yields satisfactory results
Cao, Z, Liu, X, Xu, J, Zhang, J, Yang, Y, Zhou, J, Xu, X & Lowry, GV 2017, 'Removal of Antibiotic Florfenicol by Sulfide-Modified Nanoscale Zero-Valent Iron', Environmental Science & Technology, vol. 51, no. 19, pp. 11269-11277.
View/Download from: Publisher's site
View description>>
Florfenicol (FF, C12H14Cl2FNO4S), an emerging halogenated organic contaminant of concern was effectively degraded in water by sulfidized nanoscale zerovalent iron (S-nZVI). Sulfidized nZVI (62.5 m2 g-1) that was prepared using a one-step method resulted in small Fe0/Fe-sulfide particles that were more stable against aggregation than unsulfidized nZVI (10.2 m2 g-1). No obvious removal of FF was observed by unsulfidized nZVI. S-nZVI degraded FF, having a surface area normalized reaction rate constant of 3.1 × 10-4 L m-2 min-1. The effects of the S/Fe molar ratio, initial FF concentration, initial pH, temperature, and water composition on the removal of FF by S-nZVI, and on the formation of reaction products, were systematically investigated. Both dechlorination and defluorination were observed, resulting in four degradation products (C12H15ClFNO4S, C12H16FNO4S, C12H17NO4S, and C12H17NO5S). High removal efficiencies of FF by S-nZVI were achieved in groundwater, river water, seawater, and wastewater. The reactivity of S-nZVI was relatively unaffected by the presence of both dissolved ions and organic matter in the waters tested.
Chakraborty, S, Paul, M, Murshed, M & Ali, M 2017, 'Adaptive weighted non-parametric background model for efficient video coding', Neurocomputing, vol. 226, pp. 35-45.
View/Download from: Publisher's site
Chekli, L, Corjon, E, Tabatabai, SAA, Naidu, G, Tamburic, B, Park, SH & Shon, HK 2017, 'Performance of titanium salts compared to conventional FeCl3 for the removal of algal organic matter (AOM) in synthetic seawater: Coagulation performance, organic fraction removal and floc characteristics', Journal of Environmental Management, vol. 201, pp. 28-36.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd During algal bloom periods, operation of seawater reverse osmosis (SWRO) pretreatment processes (e.g. ultrafiltration (UF)) has been hindered due to the high concentration of algal cells and algal organic matter (AOM). The present study evaluated for the first time the performance of titanium salts (i.e. titanium tetrachloride (TiCl4) and polytitanium tetrachloride (PTC)) for the removal of AOM in seawater and results were compared with the conventional FeCl3 coagulant. Previous studies already demonstrated that titanium salts not only provide a cost-effective alternative to conventional coagulants by producing a valuable by-product but also minimise the environmental impact of sludge production. Results from this study showed that both TiCl4 and PTC achieved better performance than FeCl3 in terms of turbidity, UV254 and dissolved organic carbon (DOC) removal at similar coagulant dose. Liquid chromatography – organic carbon detection (LC-OCD) was used to determine the removal of AOM compounds based on their molecular weight (MW). This investigation revealed that both humic substances and low MW organics were preferentially removed (i.e. up to 93% removal) while all three coagulants showed poorer performance for the removal of high MW biopolymers (i.e. less than 50% removal). The detailed characterization of flocs indicated that both titanium coagulants can grow faster, reach larger size and present a more compact structure, which is highly advantageous for the design of smaller and more compact mixing and sedimentation tanks. Both titanium coagulants also presented a higher ability to withstand shear force, which was related to the higher amount of DOC adsorbed with the aggregated flocs. Finally, TiCl4 had a better recovery after breakage suggesting that charge neutralization may be the dominant mechanism for this coagulant, while the lower recovery of both PTC and FeCl3 indicated that sweep flocculation is also a contributing mechan...
Chekli, L, Eripret, C, Park, SH, Tabatabai, SAA, Vronska, O, Tamburic, B, Kim, JH & Shon, HK 2017, 'Coagulation performance and floc characteristics of polytitanium tetrachloride (PTC) compared with titanium tetrachloride (TiCl 4 ) and ferric chloride (FeCl 3 ) in algal turbid water', Separation and Purification Technology, vol. 175, pp. 99-106.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Seasonal green algae blooms in freshwaters have raised attention on the need to develop novel effective treatment processes for the removal of algae in water. In the present study, the performance of newly developed polytitanium tetrachloride (PTC) coagulant for the removal of freshwater microalga Chlorella vulgaris has been investigated and compared with titanium tetrachloride (TiCl4) coagulant and the conventional ferric chloride (FeCl3) coagulant. The main benefit of using titanium-based coagulants is that the sludge produced after flocculation may be recycled into a valuable product: titanium dioxide photocatalyst. Both titanium-based coagulants achieved good flocculation over a broader pH range and coagulant dose compared to conventional FeCl3 coagulant. All three coagulants achieved comparable performance in terms of turbidity removal (i.e. turbidity removal efficiency >97%); although TiCl4 performed slightly better at the lower tested dose (i.e. <9 mg/L). Zeta potential measurements indicated that charge neutralisation may not be the sole mechanism involved in the coagulation of algae for all three coagulants. Analysis of the dynamic floc size variation during floc breakage showed no regrowth after floc breakage for the three coagulants. The flocs formed by both Ti-based coagulants were larger than those formed by FeCl3 and also grew at a faster rate. This study indicates that Ti-based coagulants are effective and promising coagulants for algae removal in water.
Chekli, L, Kim, JE, El Saliby, I, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, T & Kyong Shon, H 2017, 'Fertilizer drawn forward osmosis process for sustainable water reuse to grow hydroponic lettuce using commercial nutrient solution', Separation and Purification Technology, vol. 181, pp. 18-28.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. This study investigated the sustainable reuse of wastewater using fertilizer drawn forward osmosis (FDFO) process through osmotic dilution of commercial nutrient solution for hydroponics, a widely used technique for growing plants without soil. Results from the bench-scale experiments showed that the commercial hydroponic nutrient solution (i.e. solution containing water and essential nutrients) exhibited similar performance (i.e., water flux and reverse salt flux) to other inorganic draw solutions when treating synthetic wastewater. The use of hydroponic solution is highly advantageous since it provides all the required macro- (i.e., N, P and K) and micronutrients (i.e., Ca, Mg, S, Mn, B, Zn and Mo) in a single balanced solution and can therefore be used directly after dilution without the need to add any elements. After long-term operation (i.e. up to 75% water recovery), different physical cleaning methods were tested and results showed that hydraulic flushing can effectively restore up to 75% of the initial water flux while osmotic backwashing was able to restore the initial water flux by more than 95%; illustrating the low-fouling potential of the FDFO process. Pilot-scale studies demonstrated that the FDFO process is able to produce the required nutrient concentration and final water quality (i.e., pH and conductivity) suitable for hydroponic applications. Coupling FDFO with pressure assisted osmosis (PAO) in the later stages could help in saving operational costs (i.e., energy and membrane replacement costs). Finally, the test application of nutrient solution produced by the pilot FDFO process to hydroponic lettuce showed similar growth pattern as the control without any signs of nutrient deficiency.
Chekli, L, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, T & Shon, HK 2017, 'Evaluation of fertilizer-drawn forward osmosis for sustainable agriculture and water reuse in arid regions', Journal of Environmental Management, vol. 187, pp. 137-145.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd The present study focused on the performance of the FDFO process to achieve simultaneous water reuse from wastewater and production of nutrient solution for hydroponic application. Bio-methane potential (BMP) measurements were firstly carried out to determine the effect of osmotic concentration of wastewater achieved in the FDFO process on the anaerobic activity. Results showed that 95% water recovery from the FDFO process is the optimum value for further AnMBR treatment. Nine different fertilizers were then tested based on their FO performance (i.e. water flux, water recovery and reverse salt flux) and final nutrient concentration. From this initial screening, ammonium phosphate monobasic (MAP), ammonium sulfate (SOA) and mono-potassium phosphate were selected for long term experiments to investigate the maximum water recovery achievable. After the experiments, hydraulic membrane cleaning was performed to assess the water flux recovery. SOA showed the highest water recovery rate, up to 76% while KH2PO4 showed the highest water flux recovery, up to 75% and finally MAP showed the lowest final nutrient concentration. However, substantial dilution was still necessary to comply with the standards for fertigation even if the recovery rate was increased.
Chen, C, Guo, W, Ngo, HH, Chang, SW, Duc Nguyen, D, Dan Nguyen, P, Bui, XT & Wu, Y 2017, 'Impact of reactor configurations on the performance of a granular anaerobic membrane bioreactor for municipal wastewater treatment', International Biodeterioration & Biodegradation, vol. 121, pp. 131-138.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This study compared overall performance of an external granular anaerobic membrane bioreactor and a submerged granular anaerobic membrane bioreactor (EG-AnMBR and SG-AnMBR, respectively), to determine which type of G-AnMBRs is more preferred for municipal wastewater treatment. Both systems presented similar COD removal efficiencies (over 91%) and methane yield of 160 mL CH4 (STP) (g COD removed)−1 although volatile fatty acids (VFA) accumulation was found in the SG-AnMBR. Membrane direct incorporation into the SG-AnMBR significantly affected the concentration and properties of microbial products (e.g. soluble microbial products (SMP) and extracellular polymeric substances (EPS)) in the cake layer, mixed liquor and granular sludge, as well as granular sludge size and settleability. The EG-AnMBR demonstrated less SMP and EPS in the mixed liquor and cake layer, which might reduce the cake layer resistance and lower the fouling rate. Liquid chromatography-organic carbon detection (LC-OCD) analysis of foulant revealed that biopolymers along with low molecular weight neutrals and acids and building blocks were responsible for higher fouling propensity in the SG-AnMBR. It is evident that compared to the SG-AnMBR, the EG-AnMBR serves as a better G-AnMBR configuration for municipal wastewater treatment due to less fouling propensity and superior granule quality.
Chen, C, Guo, WS, Ngo, HH, Liu, Y, Du, B, Wei, Q, Wei, D, Nguyen, DD & Chang, SW 2017, 'Evaluation of a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) for municipal wastewater treatment', Renewable Energy, vol. 111, pp. 620-627.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This study compared a conventional granular anaerobic membrane bioreactor (CG-AnMBR) with a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) in terms of treatment performance, granular sludge properties, membrane fouling behaviour and biogas production. The SG-AnMBR showed better organics and nutrient removal, and enhanced methane yield at 156.3 ± 5.8 mL CH4(STP)/g CODremoved. Granular sludge from the SG-AnMBR had superior quality with better settleability, larger particle size, higher EPS content and more granule abundance. The SG-AnMBR also exhibited slower fouling development with 50.7% lower total filtration resistance than those of the CG-AnMBR. Sponge addition effectively affected the concentration and properties of microbial products (e.g. soluble microbial products (SMP) and extracellular polymeric substances (EPS)) in granular sludge, cake layer as well as settling zone mixed liquor, thus alleviating the fouling propensity. The liquid chromatography-organic carbon detection (LC-OCD) analysis suggested that sponge addition reduced the concentrations of biopolymers, low molecular weight neutrals and acids, and building blocks of the foulants. Compared with the SG-AnMBR, GC-MS analysis confirmed the accumulation of volatile fatty acids, particularly acetic acid in the CG-AnMBR. It is evident that the SG-AnMBR could be a promising solution for improving overall G-AnMBR performance and substantially mitigating membrane fouling.
Chen, G, Liu, R, Shon, HK, Wang, Y, Song, J, Li, X-M & He, T 2017, 'Open porous hydrophilic supported thin-film composite forward osmosis membrane via co-casting for treatment of high-salinity wastewater', Desalination, vol. 405, pp. 76-84.
View/Download from: Publisher's site
View description>>
© 2016 High-performance thin film composite (TFC) forward osmosis (FO) membranes with a low degree of internal concentration polarization (ICP) are critical for concentrating high-salinity wastewaters. This report focuses on the preparation of TFC FO membranes via a sacrificial approach. In order to improve the FO flux, hydrophilicity and morphology of the support membrane were mainly investigated. The hydrophilicity of the polysulfone (PSF) substrate was tuned by blending with sulfonated poly (ether ether ketone) (SPEEK), and the resulting SPEEK blended PSF membrane was denoted as SPSF substrate. The pore structure of the SPSF membrane was tailored by the application of a co-casting technique, which yielded a TFC membrane with a structure parameter (S) of 191 μm. In contrast, the TFC membranes based on the PSF and SPSF substrates through single layer casting showed S values of 527 μm and 361 μm, respectively. These results indicate that the combined hydrophilicity and open pore structure are responsible for the lowered S value. Further application of the hydrophilic substrate based TFC membranes in the treatment of high salinity wastewaters (10 wt%) demonstrated the higher initial water flux (28.3 L/m2·h) with a water recovery rate of 53.2% in comparison to the TFC membrane based on the pristine PSF through the single layer casting. This new method paves a way to generate high-performing FO membranes.
Chen, H, Yue, Y, Jin, W, Zhou, X, Wang, Q, Gao, S-H, Xie, G-J, Du, S, Tu, R, Han, S & Guo, K 2017, 'Enrichment and characteristics of ammonia-oxidizing archaea in wastewater treatment process', Chemical Engineering Journal, vol. 323, pp. 465-472.
View/Download from: Publisher's site
View description>>
High purity ammonia-oxidizing archaea (AOA) culture containing a single AOA strain was enriched from the filtering materials of biological aerated filter. The concentration of AOA reached 3.27 × 107 copies/mL, while its proportion was 91.40%. The AOA amoA gene sequence belonged to Nitrososphaera cluster. Ammonia concentration significantly influenced the growth of AOA in culture, while total organic carbon (TOC) concentration had no obvious effect. The optimum ammonia concentration, temperature, pH and DO concentration for growth of AOA were 1 mM, 30 °C, 7.5 and 2.65 mg/L, respectively. Under the optimum growth conditions, the AOA abundance and ammonia oxidation rate were 3.53 × 107 copies/mL and 2.54 × 10−10 mg/(copies·d).
Chen, SJ, Li, WG, Ruan, CK, Sagoe-Crentsil, K & Duan, WH 2017, 'Pore shape analysis using centrifuge driven metal intrusion: Indication on porosimetry equations, hydration and packing', Construction and Building Materials, vol. 154, pp. 95-104.
View/Download from: Publisher's site
View description>>
© 2017 Porosity is an intrinsic property of many cementitious materials. This study uses a new centrifugation-based low-melting-point metal intrusion technique to characterize and analyze the shape of pores in cementitious materials. Low energy electrons with ultra-long beam dwell time are used to obtain nano meter level resolution of the pore shape. Three descriptors, namely circularity, solidity, and aspect ratio, are proposed to represent the area-perimeter relationship, hydration and packing and 3D shape of the pores, respectively. Circularity is found to hold a consistent power correlation with pore size. Based on this correlation, the Washburn's equation is modified to correct the biased prediction of pore size using mercury intrusion porosimetry (MIP). Solidity, is found to decrease with increased pore size, denser packing of cement particles and more hydration products. Aspect ratio of the observed pores is found to average at about 2 representing an oblate ellipsoid shape of pore in 3D space.
Chen, W, Xie, X, Wang, J, Pradhan, B, Hong, H, Bui, DT, Duan, Z & Ma, J 2017, 'A comparative study of logistic model tree, random forest, and classification and regression tree models for spatial prediction of landslide susceptibility', CATENA, vol. 151, pp. 147-160.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. The main purpose of the present study is to use three state-of-the-art data mining techniques, namely, logistic model tree (LMT), random forest (RF), and classification and regression tree (CART) models, to map landslide susceptibility. Long County was selected as the study area. First, a landslide inventory map was constructed using history reports, interpretation of aerial photographs, and extensive field surveys. A total of 171 landslide locations were identified in the study area. Twelve landslide-related parameters were considered for landslide susceptibility mapping, including slope angle, slope aspect, plan curvature, profile curvature, altitude, NDVI, land use, distance to faults, distance to roads, distance to rivers, lithology, and rainfall. The 171 landslides were randomly separated into two groups with a 70/30 ratio for training and validation purposes, and different ratios of non-landslides to landslides grid cells were used to obtain the highest classification accuracy. The linear support vector machine algorithm (LSVM) was used to evaluate the predictive capability of the 12 landslide conditioning factors. Second, LMT, RF, and CART models were constructed using training data. Finally, the applied models were validated and compared using receiver operating characteristics (ROC), and predictive accuracy (ACC) methods. Overall, all three models exhibit reasonably good performances; the RF model exhibits the highest predictive capability compared with the LMT and CART models. The RF model, with a success rate of 0.837 and a prediction rate of 0.781, is a promising technique for landslide susceptibility mapping. Therefore, these three models are useful tools for spatial prediction of landslide susceptibility.
Chen, W-H, Hsu, H-J, Kumar, G, Budzianowski, WM & Ong, HC 2017, 'Predictions of biochar production and torrefaction performance from sugarcane bagasse using interpolation and regression analysis', Bioresource Technology, vol. 246, pp. 12-19.
View/Download from: Publisher's site
Chen, X, Liu, Y, Peng, L & Ni, B-J 2017, 'Perchlorate, nitrate, and sulfate reduction in hydrogen-based membrane biofilm reactor: Model-based evaluation', Chemical Engineering Journal, vol. 316, pp. 82-90.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. A biofilm model was developed to evaluate the key mechanisms including microbially-mediated ClO4−, NO3−, and SO42−reduction in the H2-based membrane biofilm reactor (MBfR). Sensitivity analysis indicated that the maximum growth rate of H2-based denitrification (μ1) and maximum growth rate of H2-based SO42−reduction (μ3) could be reliably estimated by fitting the model predictions to the experimental measurements. The model was first calibrated using the experimental data of a single-stage H2-based MBfR fed with different combinations of ClO4−, NO3−, and/or SO42−together with a constant dissolved oxygen (DO) concentration at three operating stages. μ1and μ3were determined at 0.133 h−1and 0.0062 h−1, respectively, with a good level of identifiability. The model and the parameter values were further validated based on the experimental data of a two-stage H2-based MBfR system fed with ClO4−, NO3−, SO42−, and DO simultaneously but at different feeding rates during two running phases. The validated model was then applied to evaluate the quantitative and systematic effects of key operating conditions on the reduction of ClO4−, NO3−, and SO42−as well as the steady-state microbial structure in the biofilm of a single-stage H2-based MBfR. The results showed that i) a higher influent ClO4−concentration led to a higher ClO4−removal efficiency, compensated by a slightly decreasing SO42−removal; ii) the H2loading should be properly managed at certain critical level to maximize the ClO4−and NO3−removal while limiting the growth of sulfate reducing bacteria which would occur in the case of excessive H2supply; and iii) a moderate hydraulic retention time and a relatively thin biofilm were required to maintain high-level removal of ClO4−and NO3−but restrict the SO42−reduction.
Cheng, L, Chen, Y, Zheng, YY, Zhan, Y, Zhao, H & Zhou, JL 2017, 'Bioaccumulation of sulfadiazine and subsequent enzymatic activities in Chinese mitten crab (Eriocheir sinensis)', Marine Pollution Bulletin, vol. 121, no. 1-2, pp. 176-182.
View/Download from: Publisher's site
View description>>
The bioaccumulation of sulfadiazine and subsequent enzymatic activities in Chinese mitten crab (Eriocheir sinensis) were studied in microcosms, by exposing to 50, 100, 500 and 1000ng/L of sulfadiazine for 44days. An effective method for extracting sulfadiazine in crab tissues was established by modifying the cleanup method after ultrasound extraction, with improved recoveries of 61.8%, 93.7% and 100.5% in gill, muscle and liver samples. The results showed that sulfadiazine residues were all <3ng/g dry weight in different tissues, and that sulfadiazine bioaccumulation in crab was not dose-dependent. A significantly negative correlation was observed between acetylcholinesterase activity and the residue concentration of sulfadiazine during exposure to 50ng/L and 1000ng/L, and between alkaline phosphatase and sulfadiazine residues in the 100ng/L exposure group in the gill, suggesting that the two enzymes played an important role in the metabolism of sulfadiazine in crab.
Choi, Y, Naidu, G, Jeong, S, Vigneswaran, S, Lee, S, Wang, R & Fane, AG 2017, 'Experimental comparison of submerged membrane distillation configurations for concentrated brine treatment', Desalination, vol. 420, pp. 54-62.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Membrane distillation (MD) is an attractive technology for seawater reverse osmosis (SWRO) brine treatment. Submerged MD (S-MD) offers an additional advantage of a compact system compared to cross-flow MD. This study evaluated the performances of three different S-MD configurations; submerged direct contact membrane distillation (S-DCMD), submerged vacuum direct contact membrane distillation (S-VDCMD) and submerged vacuum membrane distillation (S-VMD) for SWRO brine treatment. A 13–77% higher water flux was obtained by S-MDs with vacuum incorporation (S-VMD and S-VDCMD) compared to S-DCMD, attributed to higher driving force. Evaluation on the influence of feed concentration and permeate temperature revealed that S-MD with high vacuum was significantly affected by feed concentration. Meanwhile S-DCMD was more severely affected by feed temperature losses, based on the tendency of membrane pore crystallization formation. The crystallization tendency on the membrane surface was influenced by the presence of vacuum pressure. A repeated cycle of S-DCMD with membrane air-backwashing was effective for flux recovery and to reduce membrane crystallization, enabling to concentrate SWRO brine by 2.8 times of volume concentration factor.
Chua, L, Head, K, Thomas, P & Stuart, B 2017, 'FTIR and Raman microscopy of organic binders and extraneous organic materials on painted ceremonial objects from the Highlands of Papua New Guinea', Microchemical Journal, vol. 134, pp. 246-256.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. This paper presents a challenging case where organic materials in micro-sized paint samples extracted from mid-20th century ceremonial objects of the Papua New Guinea (PNG) Highlands are characterized using FTIR microscopy, with the aid of solvent extraction and pre-treatment with hydrofluoric acid (HF) targeted for micro-sized samples, as well as Raman microscopy and SEM-EDS. An eclectic range of binder classes including plant-based organic matter, animal fat, wax, natural and synthetic resin, were identified on several ceremonial objects based on spectral signatures. The tree resins detected (tigaso oil and kilt tree resin) are specific to the natural flora from the PNG Highlands. Tannin-rich charred wood forming the base substrate of different ceremonial objects was also identified. In addition, degradation products from metal soaps from both synthetic and biological sources were identified.
Chul Woo, Y, Chen, Y, Tijing, LD, Phuntsho, S, He, T, Choi, J-S, Kim, S-H & Kyong Shon, H 2017, 'CF4 plasma-modified omniphobic electrospun nanofiber membrane for produced water brine treatment by membrane distillation', Journal of Membrane Science, vol. 529, pp. 234-242.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. This study describes the development and performance of an omniphobic poly(vinylidene fluoride) (PVDF) membrane by electrospinning and CF4plasma surface modification for air gap membrane distillation (AGMD). The effect of different duration of plasma treatment on the nanofiber membrane characteristics was investigated. The AGMD performance of the membranes was evaluated using real reverse osmosis (RO) brine produced from coal seam gas (CSG) water that was added with low surface tension liquid (surfactant) as feed solution. Results indicated the formation of new CF2-CF2and CF3bonds after plasma treatment, which lowered the surface energy of the membrane, providing omniphobic property, as indicated by its wetting resistance to different low surface tension liquids such as methanol, mineral oil and ethylene glycol. Though no appreciative changes in morphology of the membrane were observed after plasma treatment, optimal treatment condition of 15 min (i.e., P/CF-15 membrane) exhibited lotus effect membrane surface with increased liquid entry pressure of 187 kPa compared to 142 kPa for neat membrane. AGMD performance showed stable normalized flux (initial flux of 15.3 L/m2h) and rejection ratio (100%) for P/CF-15 even with the addition of up to 0.7 mM sodium dodecyl sulfate surfactant to the RO brine from CSG produced water feed, while commercial PVDF membrane suffered membrane wetting after 0.3 mM of surfactant addition. Based on the results, the present omniphobic membrane has good potential for producing clean water from challenging waters containing high salinity and organic contaminants.
Cu, P & Ball, JE 2017, 'Parameter estimation for a large catchment', Australasian Journal of Water Resources, vol. 21, no. 1, pp. 20-33.
View/Download from: Publisher's site
View description>>
© 2017 Engineers Australia. Estimation of parameter values is an essential step in the application of catchment modelling systems. This step is time-consuming and requires considerable effort. While a variety of approaches have been developed to accelerate the process, this paper proposes a method to reduce significantly the number of parameters for a large catchment when a semi-distributed catchment modelling system is applied. Past studies have reported on the use of a scaling parameter to adjust parameter values from their initial values, introduced herein is the use of a scaling parameter together with a variation coefficient. This enables the spatial variation of changes in parameter values across the catchment to be considered. A case study was conducted for a 14,000 km2 catchment to assess the validity of this approach where the focus of the catchment modelling was the prediction of a design flood statistic. This catchment was divided into 155 subcatchments with 5 sensitive parameters per subcatchment. Hence, a total of 775 parameters needed to be considered. Using the proposed approach, the number of parameters considered during the calibration was reduced to 8 coefficients which was reasonable for a calibration and validation process that also enabled an estimate of the parameter variability.
Cu, PT & Ball, JE 2017, 'The influence of the calibration metric on design flood estimation using continuous simulation', International Journal of River Basin Management, vol. 15, no. 1, pp. 9-20.
View/Download from: Publisher's site
View description>>
© 2016 International Association for Hydro-Environment Engineering and Research. Estimation of design flood flow has been and remains a concern for both hydrologic research and hydrologic practice. Knowledge of design flood flows provides a basis for sustainable flood management, which has the aim of reducing flood risk, thereby protecting people’s lives and property. Design floods for a given location can be estimated by a number of approaches including analysis of past flood statistics and the use of catchment modelling. When catchment modelling approaches are applied estimation of design flood flows, there is a need to calibrate the model parameters. As part of this calibration process, a calibration metric, or fitness measure, is needed to enable assessment of alternative sets of parameter values. Presented herein is an investigation into design flood quantiles derived from predictions obtained from a continuous catchment modelling system when alternative calibration metrics are used to assess the suitability of parameter values. Two alternative calibration metrics are considered with one calibration metric aimed at ensuring replication of recorded hydrographs and the second calibration metric aimed at ensuring replication of the statistical characteristics of the annual maxima series. It was found that use of the later calibration metric resulted in better reproduction of the flood probability model estimated from the historical data while reproduction of the recorded hydrographs (i.e. the first calibration metric) did not ensure reproduction of the flood probability model.
da Rocha, CG & Sattler, MA 2017, 'Improving Acceptance of More Sustainable Technologies: Exploratory Study in Brazil', Journal of Urban Planning and Development, vol. 143, no. 2, pp. 05016015-05016015.
View/Download from: Publisher's site
Dackermann, U, Yu, Y, Niederleithinger, E, Li, J & Wiggenhauser, H 2017, 'Condition Assessment of Foundation Piles and Utility Poles Based on Guided Wave Propagation Using a Network of Tactile Transducers and Support Vector Machines', Sensors, vol. 17, no. 12, pp. 2938-2938.
View/Download from: Publisher's site
View description>>
© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This paper presents a novel non-destructive testing and health monitoring system using a network of tactile transducers and accelerometers for the condition assessment and damage classification of foundation piles and utility poles. While in traditional pile integrity testing an impact hammer with broadband frequency excitation is typically used, the proposed testing system utilizes an innovative excitation system based on a network of tactile transducers to induce controlled narrow-band frequency stress waves. Thereby, the simultaneous excitation of multiple stress wave types and modes is avoided (or at least reduced), and targeted wave forms can be generated. The new testing system enables the testing and monitoring of foundation piles and utility poles where the top is inaccessible, making the new testing system suitable, for example, for the condition assessment of pile structures with obstructed heads and of poles with live wires. For system validation, the new system was experimentally tested on nine timber and concrete poles that were inflicted with several types of damage. The tactile transducers were excited with continuous sine wave signals of 1 kHz frequency. Support vector machines were employed together with advanced signal processing algorithms to distinguish recorded stress wave signals from pole structures with different types of damage. The results show that using fast Fourier transform signals, combined with principal component analysis as the input feature vector for support vector machine (SVM) classifiers with different kernel functions, can achieve damage classification with accuracies of 92.5% ± 7.5%.
Dadzie, J, Ding, G & Runeson, G 2017, 'Relationship between Sustainable Technology and Building Age: Evidence from Australia', Procedia Engineering, vol. 180, pp. 1131-1138.
View/Download from: Publisher's site
View description>>
© 2017 The Authors. Published by Elsevier Ltd. The overall energy performance of existing buildings is an important consideration in decisions to demolish or refurbish. To refurbish means to use sustainable technologies (STs) to improve energy efficiency, health of occupants, energy cost and environmental sustainability. This paper examines the use of STs to streamline energy efficiency in existing buildings. It analyses various buildings of different ages retrofitted over the last 5 years and the various STs used to enhance energy efficiency through an in-built case study in a survey. The results show that buildings less than 15 years old have been improved with fewer façade technologies compared to those between 16-30 years old. Overall, buildings aged between 16-30 years are the most improved with STs followed by buildings less than 15 years old and those between 31-45 years, in that order. Buildings over 45 years are the least improved with STs for energy efficiency. They had received less than 10% of ST technology injection. The lighting systems, sensors, energy efficient equipment and passive strategies have been applied improve energy efficiency across all ages. However, solar technologies, HVAC systems, façade technologies and building management systems are the least adopted across all ages.
Daly, L, Bland, PA, Dyl, KA, Forman, LV, Evans, KA, Trimby, PW, Moody, S, Yang, L, Liu, H, Ringer, SP, Ryan, CG & Saunders, M 2017, 'In situ analysis of Refractory Metal Nuggets in carbonaceous chondrites', Geochimica et Cosmochimica Acta, vol. 216, pp. 61-81.
View/Download from: Publisher's site
Daly, L, Bland, PA, Dyl, KA, Forman, LV, Saxey, DW, Reddy, SM, Fougerouse, D, Rickard, WDA, Trimby, PW, Moody, S, Yang, L, Liu, H, Ringer, SP, Saunders, M & Piazolo, S 2017, 'Crystallography of refractory metal nuggets in carbonaceous chondrites: A transmission Kikuchi diffraction approach', Geochimica et Cosmochimica Acta, vol. 216, pp. 42-60.
View/Download from: Publisher's site
Damanik, N, Ong, HC, Chong, WT & Silitonga, AS 2017, 'Biodiesel production from Calophyllum inophyllum−palm mixed oil', Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 39, no. 12, pp. 1283-1289.
View/Download from: Publisher's site
View description>>
The objective of this study is to investigate the biodiesel production from Calophyllum inophyllum −palm mixed oil. The C. inophyllum–palm biodiesel (C. inophyllum palm oil methyl ester, CPME) is first produced by mixing the crude oils at an equal ratio of 50:50 vol%, followed by degumming, acid-catalyzed esterification, purification, and, last, alkaline-catalyzed transesterification. With this systematic procedure, the acid value of the CPME is 0.4 mg KOH/g, resulting in a significant enhancement of oxidation stability (114.21 h). The results indicate that the fatty acid methyl ester composition of the CPME may be the reason for its larger higher heating value (39.4 MJ/kg) and lower kinematic viscosity (4.15 mm2/s). In short, CPME satisfied the ASTM D6751 and EN 14214 standards as a promising alternative fuel in the future.
Dantas Neto, SA, Indraratna, B, Oliveira, DAF & de Assis, AP 2017, 'Modelling the Shear Behaviour of Clean Rock Discontinuities Using Artificial Neural Networks', Rock Mechanics and Rock Engineering, vol. 50, no. 7, pp. 1817-1831.
View/Download from: Publisher's site
Deng, Y, Kan, ME, Indraratna, B & Zhong, R 2017, 'Finite Element Analysis of Vacuum Consolidation With Modified Compressibility and Permeability Parameters', International Journal of Geosynthetics and Ground Engineering, vol. 3, no. 2.
View/Download from: Publisher's site
View description>>
© 2017, Springer International Publishing Switzerland. Laboratory tests and case history studies indicate that soil subjected to vacuum preloading may not behave the same as ground treated by traditional surcharge preloading. In detail, soil compression under vacuum pressure is smaller than or equal to that induced by positive pressure with the same magnitude; soil rebound after stopping the vacuum is not as high as after removing the surcharge; and the consolidation rate is usually faster under vacuum pressure than with surcharge preloading. Analysis of vacuum consolidation with existing methods cannot gain all these differences. Thus, in this study, three factors for adjusting compressibility and permeability are proposed based on past laboratory and field results which are used in a finite element analysis of soft soil foundation under vacuum-assisted preloading. This proposed method can be incorporated in existing computer programs associated with classical soil models (e.g., the modified Cam-Clay model and the Soft-Soil model); it is then examined via three distinct simulation scenarios including a laboratory model test and two prototype field cases. The improved accuracy in relation to consolidation by the proposed method is demonstrated and practical ranges for the adjustment factors are discussed.
Deng, Y-B, Liu, G-B, Indraratna, B, Rujikiatkamjorn, C & Xie, K-H 2017, 'Model Test and Theoretical Analysis for Soft Soil Foundations Improved by Prefabricated Vertical Drains', International Journal of Geomechanics, vol. 17, no. 1, pp. 04016045-04016045.
View/Download from: Publisher's site
Dharma, S, Hassan, MH, Ong, HC, Sebayang, AH, Silitonga, AS & Kusumo, F 2017, 'Optimization of biodiesel production from mixed jatropha curcas-ceiba pentandra using artificial neural network- genetic algorithm: Evaluation of reaction kinetic models', Chemical Engineering Transactions, vol. 56, pp. 547-552.
View/Download from: Publisher's site
View description>>
Biodiesel production from non-edible vegetable oil is one effective way to anticipate the problems associated with fuel crisis and environmental issues. In this study, artificial neural network and genetic algorithm based Box Behnken experimental design used to optimize the parameters of the biodiesel production for mixed of Jatropha curcas?Ceiba pentandra oil such as methanol to oil ratio, agitation speed and catalyst concentration. Based on the results, the optimum operating parameters for the transesterification of the oil mixture J50C50 are as follows: methanol-To-oil ratio: 40 %v/v, agitation speed: 1,794 rpm and the catalyst concentration: 0.68 % wt. This process is carried out at constant temperature and time of 60 °C and 2 h. The theoretical yield predicted under this the highest yield for the J50C50 biodiesel with a value of 93.70 %. The model developed was validated by applying the optimum values to three independent experimental replicates with a 93.56 %. Comparison between the predicted values to the actual value with a small error percentage indicates that the regression model was reliable in predicting the conversion at any given conditions within the ranges studied. Moreover, the activation energy of 24.421 kJmol-1 and frequency factor of 1.88 x 102 min-1 was required for the transesterification process. The fuel properties of the biodiesel were measured according to ASTM D 6751 and EN14214 standards and found to be within the specifications.
Dharma, S, Hassan, MH, Ong, HC, Sebayang, AH, Silitonga, AS, Kusumo, F & Milano, J 2017, 'Experimental study and prediction of the performance and exhaust emissions of mixed Jatropha curcas-Ceiba pentandra biodiesel blends in diesel engine using artificial neural networks', Journal of Cleaner Production, vol. 164, pp. 618-633.
View/Download from: Publisher's site
Du, G, Huang, X, Li, Y, Ouyang, Q & Wang, J 2017, 'Performance of a semi-active/passive integrated isolator based on a magnetorheological elastomer and spring', Smart Materials and Structures, vol. 26, no. 9, pp. 095024-095024.
View/Download from: Publisher's site
View description>>
© 2017 IOP Publishing Ltd. This paper reports an investigation on a semi-active/passive integrated vibration isolator utilizing a magnetorheological elastomer (MRE) and spring. To overcome the main shortcoming of passive isolation systems, i.e. lack of adaptability, the semi-active/passive integrated isolator (SAPII) based on an MRE and spring is designed and prototyped. The magnetic circuit is optimized by finite element analysis to fully unlock the unique features of the MRE. The dynamic response characteristic of the SAPII is experimentally investigated under a sweep frequency test. A dynamic model of the SAPII vibration isolation system is established on the basis of the Kelvin model. The model parameters, such as equivalent stiffness and equivalent damping, are identified from experimental data. An ON-OFF control law based on the minimal displacement transmissibility is designed for isolation control of the sinusoid excitation. Two control laws, i.e. ON-OFF control and fuzzy logic control, are designed for vibration isolation of random excitation. Finally, the effectiveness of these control laws is verified by numerical simulation and experiment.
Duan, H, Ye, L, Erler, D, Ni, B-J & Yuan, Z 2017, 'Quantifying nitrous oxide production pathways in wastewater treatment systems using isotope technology – A critical review', Water Research, vol. 122, pp. 96-113.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Nitrous oxide (N2O) is an important greenhouse gas and an ozone-depleting substance which can be emitted from wastewater treatment systems (WWTS) causing significant environmental impacts. Understanding the N2O production pathways and their contribution to total emissions is the key to effective mitigation. Isotope technology is a promising method that has been applied to WWTS for quantifying the N2O production pathways. Within the scope of WWTS, this article reviews the current status of different isotope approaches, including both natural abundance and labelled isotope approaches, to N2O production pathways quantification. It identifies the limitations and potential problems with these approaches, as well as improvement opportunities. We conclude that, while the capabilities of isotope technology have been largely recognized, the quantification of N2O production pathways with isotope technology in WWTS require further improvement, particularly in relation to its accuracy and reliability.
Dumée, LF, Maina, JW, Merenda, A, Reis, R, He, L & Kong, L 2017, 'Hybrid thin film nano-composite membrane reactors for simultaneous separation and degradation of pesticides', Journal of Membrane Science, vol. 528, pp. 217-224.
View/Download from: Publisher's site
View description>>
Membrane reactors typically combine chemically reactive pathways with separation opportunities to increase conversion and chemical processes efficiency in liquid effluents treatment. The treatment of industrial bio-products, waste mixed solvents and agro-chemicals with such reactors are however challenging due to the natural affinity of such reactive materials for organic and biological matter leading to surface adsorption and fouling tendencies. Here, hybrid thin film composite catalytic membranes offering superior flow permeation characteristics, extremely high retention of low molecular weight organics and partial salt rejection capabilities were for the first time synthesized. Catalytic silver-metal nano-materials were for the first time homogeneously templated and encapsulated across metal organic frameworks nano-particles and incorporated across the top surface of poly(amide) thin films during interfacial polymerization. These novel materials offer high catalytic/anti-microbial behaviours due to the nano-structure of the metal nano-particles reduced within the metal organic framework template, forming unique hierarchical sub-100 nm hybrid nano-structures. These ultra-thin but yet dense membranes were able to simultaneously degrade chemicals and filter contaminants, opening new pathways for the design of the next generation thin film nano-composite membranes. Catalytic properties and homogeneity were evaluated for the Fenton-like heterogeneous catalytic degradation of 2,4-Dichlorophenoxyacetic acid, a waste pesticide contained in agricultural wastewater.
Dumée, LF, Yi, Z, Tardy, B, Merenda, A, des Ligneris, E, Dagastine, RR & Kong, L 2017, 'Silver metal nano-matrixes as high efficiency and versatile catalytic reactors for environmental remediation', Scientific Reports, vol. 7, no. 1, p. 45112.
View/Download from: Publisher's site
View description>>
AbstractNano-porous metallic matrixes (NMMs) offer superior surface to volume ratios as well as enhanced optical, photonic, and electronic properties to bulk metallic materials. Such behaviours are correlated to the nano-scale inter-grain metal domains that favour the presence of electronic vacancies. In this work, continuous 3D NMMs were synthesized for the first time through a simple diffusion-reduction process whereby the aerogel matrix was functionalized with (3-Mercaptopropyl)trimethoxysilane. The surface energy of the silica monolith templates was tuned to improve the homogeneity of the reduction process while thiol functionalization facilitated the formation of a high density of seeding points for metal ions to reduce. The diameter of NMMs was between 2 and 1000 nm, corresponding to a silver loading between 1.23 and 41.16 at.%. A rates of catalytic degradation kinetics of these NMMS which is three orders of magnitude higher than those of the non-functionalized silver-silica structures. Furthermore, the enhancement in mechanical stability at nanoscale which was evaluated by Atomic Force Microscopy force measurements, electronic density and chemical inertness was assessed and critically correlated to their catalytic potential. This strategy opens up new avenues for design of complex architectures of either single or multi-metal alloy NMMs with enhanced surface properties for various applications.
Erkmen, RE, Gowripalan, N & Sirivivatnanon, V 2017, 'Elasto-plastic damage modelling of beams and columns with mechanical degradation', Computers and Concrete, vol. 19, no. 3, pp. 315-323.
View/Download from: Publisher's site
View description>>
© 2017 Techno-Press, Ltd. Within the context of continuum mechanics, inelastic behaviours of constitutive responses are usually modelled by using phenomenological approaches. Elasto-plastic damage modelling is extensively used for concrete material in the case of progressive strength and stiffness deterioration. In this paper, a review of the main features of elasto-plastic damage modelling is presented for uniaxial stress-strain relationship. It has been reported in literature that the influence of Alkali-Silica Reaction (ASR) can lead to severe degradations in the modulus of elasticity and compression strength of the concrete material. In order to incorporate the effects of ASR related degradation, in this paper the constitutive model of concrete is based on the coupled damage-plasticity approach where degradation in concrete properties can be captured by adjusting the yield and damage criteria as well as the hardening moduli related parameters within the model. These parameters are adjusted according to results of concrete behaviour from the literature. The effect of ASR on the dynamic behaviour of a beam and a column are illustrated under moving load and cyclic load cases.
Fang, F, Qiao, L-L, Ni, B-J, Cao, J-S & Yu, H-Q 2017, 'Quantitative evaluation on the characteristics of activated sludge granules and flocs using a fuzzy entropy-based approach', Scientific Reports, vol. 7, no. 1, pp. 1-9.
View/Download from: Publisher's site
View description>>
AbstractActivated sludge granules and flocs have their inherent advantages and disadvantages for wastewater treatment due to their different characteristics. So far quantitative information on their evaluation is still lacking. This work provides a quantitative and comparative evaluation on the characteristics and pollutant removal capacity of granules and flocs by using a new methodology through integrating fuzzy analytic hierarchy process, accelerating genetic algorithm and entropy weight method. Evaluation results show a higher overall score of granules, indicating that granules had more favorable characteristics than flocs. Although large sized granules might suffer from more mass transfer limitation and is prone to operating instability, they also enable a higher level of biomass retention, greater settling velocity and lower sludge volume index compared to flocs. Thus, optimized control of granule size is essential for achieving good pollutant removal performance and simultaneously sustaining long-term stable operation of granule-based reactors. This new integrated approach is effective to quantify and differentiate the characteristics of activated sludge granules and flocs. The evaluation results also provide useful information for the application of activated sludge granules in full-scale wastewater treatment plants.
Fang, J, Qiu, N, An, X, Xiong, F, Sun, G & Li, Q 2017, 'Crashworthiness design of a steel–aluminum hybrid rail using multi-response objective-oriented sequential optimization', Advances in Engineering Software, vol. 112, pp. 192-199.
View/Download from: Publisher's site
Fang, J, Sun, G, Qiu, N, Kim, NH & Li, Q 2017, 'On design optimization for structural crashworthiness and its state of the art', Structural and Multidisciplinary Optimization, vol. 55, no. 3, pp. 1091-1119.
View/Download from: Publisher's site
View description>>
© 2016, Springer-Verlag Berlin Heidelberg. Optimization for structural crashworthiness and energy absorption has become an important topic of research attributable to its proven benefits to public safety and social economy. This paper provides a comprehensive review of the important studies on design optimization for structural crashworthiness and energy absorption. First, the design criteria used in crashworthiness and energy absorption are reviewed and the surrogate modeling to evaluate these criteria is discussed. Second, multiobjective optimization, optimization under uncertainties and topology optimization are reviewed from concepts, algorithms to applications in relation to crashworthiness. Third, the crashworthy structures are summarized, from generically novel structural configurations to industrial applications. Finally, some conclusions and recommendations are provided to enable academia and industry to become more aware of the available capabilities and recent developments in design optimization for structural crashworthiness and energy absorption.
Fang, J, Sun, G, Qiu, N, Steven, GP & Li, Q 2017, 'Topology Optimization of Multicell Tubes Under Out-of-Plane Crushing Using a Modified Artificial Bee Colony Algorithm', Journal of Mechanical Design, vol. 139, no. 7.
View/Download from: Publisher's site
View description>>
Multicell tubal structures have generated increasing interest in engineering design for their excellent energy-absorbing characteristics when crushed through severe plastic deformation. To make more efficient use of the material, topology optimization was introduced to design multicell tubes under normal crushing. The design problem was formulated to maximize the energy absorption while constraining the structural mass. In this research, the presence or absence of inner walls were taken as design variables. To deal with such a highly nonlinear problem, a heuristic design methodology was proposed based on a modified artificial bee colony (ABC) algorithm, in which a constraint-driven mechanism was introduced to determine adjacent food sources for scout bees and neighborhood sources for employed and onlooker bees. The fitness function was customized according to the violation or the satisfaction of the constraints. This modified ABC algorithm was first verified by a square tube with seven design variables and then applied to four other examples with more design variables. The results demonstrated that the proposed heuristic algorithm is capable of handling the topology optimization of multicell tubes under out-of-plane crushing. They also confirmed that the optimized topological designs tend to allocate the material at the corners and around the outer walls. Moreover, the modified ABC algorithm was found to perform better than a genetic algorithm (GA) and traditional ABC in terms of best, worst, and average designs and the probability of obtaining the true optimal topological configuration.
Far, H & Flint, D 2017, 'Significance of using isolated footing technique for residential construction on expansive soils', Frontiers of Structural and Civil Engineering, vol. 11, no. 1, pp. 123-129.
View/Download from: Publisher's site
View description>>
Expansive soils cause problems with the founding of lightly loaded structures in many parts of the world. Foundation design for expansive soils is one of the most discussed and problematic issues in Australia as expansive soils were responsible for billions of dollars’ worth of damage to man-made structures such as buildings and roads. Several studies and reports indicate that one of the most common and least recognized problems causing severe structural damage to houses lies in expansive soils. In this study, a critical review has been carried out on the current Australian standards for building on expansive soils and they are compared with some techniques that are not included in the current Australian standards for residential slabs and footings. Based on the results of this review, the most effective and economical method has been proposed for construction of footings on all site classifications without restriction to 75mm of characteristic movement. In addition, it has become apparent that as design procedures for footings resting on sites with extreme characteristic movements are not included in the current Australian standards, there is a strong need for well-developed and simplified standard design procedures for characteristic soil movement of greater than 75mm to be included into the Australian Standards.
Far, H, Saleh, A & Firouzianhaji, A 2017, 'A simplified method to determine shear stiffness of thin walled cold formed steel storage rack frames', Journal of Constructional Steel Research, vol. 138, pp. 799-805.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The shear stiffness of braced frames of thin-walled cold-formed steel storage racks was experimentally and numerically investigated in order to establish the effect of connection flexibility on the accuracy of different analysis methods. The analyses which included a detailed 3D Finite Element model, a 2D frame analysis with beam elements and a simple hand calculation indicated significant variation of results compared with experimental values. A simplified modelling approach for 2D elastic analysis of braced frames was proposed. The approach is aimed at practical applications to account for the flexibility in bolted connections and leads to better approximation of the shear stiffness.
Faria, AF, Liu, C, Xie, M, Perreault, F, Nghiem, LD, Ma, J & Elimelech, M 2017, 'Thin-film composite forward osmosis membranes functionalized with graphene oxide–silver nanocomposites for biofouling control', Journal of Membrane Science, vol. 525, pp. 146-156.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Innovative approaches to prevent bacterial attachment and biofilm growth on membranes are critically needed to avoid decreasing membrane performance due to biofouling. In this study, we propose the fabrication of anti-biofouling thin-film composite membranes functionalized with graphene oxide–silver nanocomposites. In our membrane modification strategy, carboxyl groups on the graphene oxide–silver nanosheets are covalently bonded to carboxyl groups on the surface of thin-film composite membranes via a crosslinking reaction. Further characterization, such as scanning electron microscopy and Raman spectroscopy, revealed the immobilization of graphene oxide–silver nanocomposites on the membrane surface. Graphene oxide–silver modified membranes exhibited an 80% inactivation rate against attached Pseudomonas aeruginosa cells. In addition to a static antimicrobial assay, our study also provided insights on the anti-biofouling property of forward osmosis membranes during dynamic operation in a cross-flow test cell. Functionalization with graphene oxide–silver nanocomposites resulted in a promising anti-biofouling property without sacrificing the membrane intrinsic transport properties. Our results demonstrated that the use of graphene oxide–silver nanocomposites is a feasible and attractive approach for the development of anti-biofouling thin-film composite membranes.
Feng, J, Wu, D, Gao, W & Li, G 2017, 'Uncertainty analysis for structures with hybrid random and interval parameters using mathematical programming approach', Applied Mathematical Modelling, vol. 48, pp. 208-232.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Inc. A novel computational method, namely the unified perturbation mathematical programming (UPMP) approach, for hybrid uncertainty analysis of engineering structures is proposed in this paper. The presented study considers a mixture of random and interval system parameters which are frequently encountered in engineering applications. Within the UPMP approach, matrix perturbation theory is adopted in combination with the mathematical programming approach. The proposed computational method provides a non-simulative hybrid uncertainty analysis framework, which is competent to offer the extreme bounds of the statistical characteristics (i.e., mean and variance) of any concerned structural responses in computationally tractable fashion. In order to thoroughly explore various intricate aspects of the engineering system involving hybrid uncertainties, systematic numerical experiments have also been conducted. Diverse statistical analyses are implemented to identify the bounded probability profile of the uncertain structural responses. Both academic and practical engineering structures are investigated to justify the applicability, accuracy and efficiency of the proposed UPMP approach.
Fu, Q, Ruan, Q, McKenzie, TG, Reyhani, A, Tang, J & Qiao, GG 2017, 'Development of a Robust PET-RAFT Polymerization Using Graphitic Carbon Nitride (g-C3N4)', Macromolecules, vol. 50, no. 19, pp. 7509-7516.
View/Download from: Publisher's site
View description>>
The metal-free semiconductor, graphitic carbon nitride (g-C3N4), was introduced into RAFT polymerization for the first time. The production of linear polyacrylate and polyacrylamide has been achieved via PET-RAFT polymerization using g-C3N4 as a photoactive organocatalyst without prior deoxygenation. The resulting polymers display controlled molecular weights, narrow polymer dispersities, and high end-group fidelity as exemplified by 1H NMR analysis, MALDI-TOF-MS measurement, and chain extension experiment. Temporal control is illustrated by intermittent light and dark cycles, with polymer growth arrested in the absence of irradiation. The effects of changing RAFT agents (i.e., trithiocarbonates), solvents, catalyst concentrations, and degrees of polymerization in this system have been investigated. The successful polymerization of nonpurified monomer (i.e., still containing radical inhibitors) demonstrates the robust nature of the presented PET-RAFT system.
Fu, Q, Xie, K, McKenzie, TG & Qiao, GG 2017, 'Trithiocarbonates as intrinsic photoredox catalysts and RAFT agents for oxygen tolerant controlled radical polymerization', Polymer Chemistry, vol. 8, no. 9, pp. 1519-1526.
View/Download from: Publisher's site
View description>>
In this study, we reported on the discovery that trithiocarbonates (RAFT agents) can act as intrinsic photocatalyst to significantly reduce the oxygen level in a controlled radical polymerization under visible light irridation.
Gao, K, Gao, W, Wu, D & Song, C 2017, 'Nonlinear dynamic characteristics and stability of composite orthotropic plate on elastic foundation under thermal environment', Composite Structures, vol. 168, pp. 619-632.
View/Download from: Publisher's site
View description>>
An analytical computational scheme for nonlinear dynamic characteristics and stability of an eccentrically composite orthotropic plate on Winkler-Pasternak elastic foundation subjected to different axial velocities is proposed with the incorporation of mercurial damping effects under thermal environment. Incorporating the classical plate theory and Von-Kármán strain-displacement relation, the nonlinear compatibility equation is derived. The Galerkin method and Airy's stress function are implemented to establish the nonlinear dynamic buckling equation accommodating the thermal and damping effects. Then the developed nonlinear differential equations are solved numerically by the fourth-order Runge-Kutta method. The characteristics of natural frequency, linear and nonlinear vibration, frequency-amplitude curve and nonlinear dynamic responses are investigated by the developed approach with validations by other literatures. The nonlinear dynamic buckling loads are determined by using Budiansky-Roth criterion. Additionally, various effects of velocity, damping ratio, temperature change, buckling mode, initial imperfection and foundation parameter on nonlinear dynamic buckling of the orthotropic plate are discussed.
Gao, K, Gao, W, Wu, D & Song, C 2017, 'Nonlinear dynamic stability analysis of Euler–Bernoulli beam–columns with damping effects under thermal environment', Nonlinear Dynamics, vol. 90, no. 4, pp. 2423-2444.
View/Download from: Publisher's site
View description>>
© 2017, Springer Science+Business Media B.V. In this study, a unified nonlinear dynamic buckling analysis for Euler–Bernoulli beam–columns subjected to constant loading rates is proposed with the incorporation of mercurial damping effects under thermal environment. Two generalized methods are developed which are competent to incorporate various beam geometries, material properties, boundary conditions, compression rates, and especially, the damping and thermal effects. The Galerkin–Force method is developed by implementing Galerkin method into force equilibrium equations. Then for solving differential equations, different buckled shape functions were introduced into force equilibrium equations in nonlinear dynamic buckling analysis. On the other hand, regarding the developed energy method, the governing partial differential equation for dynamic buckling of beams is also derived by meticulously implementing Hamilton’s principles into Lagrange’s equations. Consequently, the dynamic buckling analysis with damping effects under thermal environment can be adequately formulated as ordinary differential equations. The validity and accuracy of the results obtained by the two proposed methods are rigorously verified by the finite element method. Furthermore, comprehensive investigations on the structural dynamic buckling behavior in the presence of damping effects under thermal environment are conducted.
Gharib, M, Khezri, M, Foster, SJ & Castel, A 2017, 'Application of the meshless generalised RKPM to the transient advection-diffusion-reaction equation', Computers & Structures, vol. 193, pp. 172-186.
View/Download from: Publisher's site
Ghosh, B, Fatahi, B & Khabbaz, H 2017, 'Analytical Solution to Analyze LTP on Column-Improved Soft Soil Considering Soil Nonlinearity', International Journal of Geomechanics, vol. 17, no. 3, pp. 04016082-04016082.
View/Download from: Publisher's site
View description>>
© 2016 American Society of Civil Engineers. In this paper, a mechanical model to idealize the load-settlement response of the load transfer platform (LTP) on column-improved soft soil is proposed. This model simultaneously considers the nonlinear and time-dependent stress-strain behavior of soft soil and the negligible tensile strength of the granular material in LTP. The reinforced Timoshenko beam is adopted to model LTP to consider the shear and flexural deformations. Soft soil is idealized by a spring-dashpot system that includes nonlinear and time-dependent behaviors. The columns and geosynthetics are modeled with linear Winkler springs in the applied range of stresses and rough elastic membrane, respectively. The response function of LTP has been derived for distributed pressure loading in the plane strain condition. The principle of superposition is used to solve the fourth-order differential equations. Parametric studies indicate that the spacing of columns, thickness of LTP, degree of consolidation of the soft soil, and tensile stiffness of the geosynthetics significantly affect the behavior of LTP. This study also evaluates the accuracy of using reinforced Timoshenko theory by comparing the results with Pasternak and Euler-Bernoulli theories.
Ghosh, B, Fatahi, B, Khabbaz, H & Yin, J-H 2017, 'Analytical study for double-layer geosynthetic reinforced load transfer platform on column improved soft soil', Geotextiles and Geomembranes, vol. 45, no. 5, pp. 508-536.
View/Download from: Publisher's site
View description>>
© 2017 The objective of this study is to propose a reasonably accurate mechanical model for double-layer geosynthetic reinforced load transfer platform (LTP) on column reinforced soft soil which can be used by practicing engineers. The developed model is very useful to study the behaviour of LTP resting on soft soil improved with conventional columns such as concrete columns, piles, and deep soil mixing columns. The negligible tensile strength of granular material in LTP, bending and shear deformations of LTP, compressibility and shearing of soft soil have been incorporated in the model. Furthermore, the results from the proposed model simulating the soft soil as Kerr foundation model are compared to the corresponding solutions when the soft soil is idealised by Winkler and Pasternak foundation models. It is observed from the comparison that the presented model can be used as a tool for a better prediction of the LTP behaviour with multi layers of geosynthetics, in comparison with the situation that soft soil is modelled by Winkler and Pasternak foundations. Furthermore, parametric studies show that as the column spacing increases, the maximum deflection of LTP and normalised tension in the geosynthetics also increase. Whereas, the maximum deflection of LTP and normalised tension in the geosynthetics decrease with increasing LTP thickness, stiffness of subsoil, and stiffness of geosynthetic reinforcement. In addition, it is observed that the use of one stronger geosynthetic layer (e.g. 1 × 2000 kN/m) with the equivalent stiffness of two geosynthetic layers (e.g. 2 × 1000 kN/m) does not result in the same settlement of LTP and the tension of the geosynthetic reinforcement when compared to two weaker geosynthetic layers.
Gibril, MBA, Bakar, SA, Yao, K, Idrees, MO & Pradhan, B 2017, 'Fusion of RADARSAT-2 and multispectral optical remote sensing data for LULC extraction in a tropical agricultural area', Geocarto International, vol. 32, no. 7, pp. 735-748.
View/Download from: Publisher's site
View description>>
In this study, we investigated the performance of different fusion and classification techniques for land cover mapping in Hilir Perak, Peninsula Malaysia using RADAR and Landsat-8 images in a predominantly agricultural area. The fusion methods used are Brovey Transform, Wavelet Transform, Ehlers and Layer Stacking and their results classified into seven different land cover classes which include (1) pixel-based classifiers (spectral angle mapper (SAM), maximum likelihood (ML), support vector machine (SVM)) and (2) Object-based (rule-based and standard nearest neighbour (NN)) classifiers. The result shows that pixel-based classification achieved maximum accuracy of the optical data classification using SVM in Landsat-8 with 74.96% accuracy compared to SAM and ML. For multisource data classification, the highest overall accuracy recorded for layer stacking (SVM) was 79.78%, Ehlers fusion (SVM) with 45.57%, Brovey fusion (SVM) with 63.70% and Wavelet fusion (SVM) 61.16%. And for object-based classifiers, the overall classification accuracy is 95.35% for rule-based and 76.33% for NN classifier, respectively. Based on the analysis of their performances, object-based and the rule-based classifiers produced the best classification accuracy from the fused images.
Gong, W, Luo, L, Li, W, Luo, X, Liang, H, Ngo, H & Guo, W 2017, 'Using Chemically Enhanced Primary Treatment (CEPT) as a Pretreatment Option for Anaerobic Digestate from Cattle Manure Digestion System', Water, vol. 9, no. 7, pp. 487-487.
View/Download from: Publisher's site
View description>>
© 2017 by the authors. Anaerobic digestate from cattle manure fermentation may pose a threat to the environment. How to stabilize the digestate's characteristics so that they do not disturb the bio-system is a critical issue for digestate management. Chemically enhanced primary treatment (CEPT) was investigated as a pretreatment option for digestate treatment. The performance of CEPT for digestate management was carried out under rapid mixing (200 r/min) and slow stirring (40 r/min), respectively. The optimal dosage of ferric chloride (FeCl 3 ) was 40 mg/L. The combination of FeCl 3 and anionic polyacrylamide (APAM) had no obvious influence on TP removal, while COD removal efficiency was improved by 15.4%. The digestate pH and temperature remained stable for CEPT application and required no adjustment. The results indicate that CEPT was effective and feasible in enhancing the removal of COD and TP for digestate pretreatment by using FeCl 3 and APAM.
Gong, Y, Gai, L, Tang, J, Fu, J, Wang, Q & Zeng, EY 2017, 'Reduction of Cr(VI) in simulated groundwater by FeS-coated iron magnetic nanoparticles', Science of The Total Environment, vol. 595, pp. 743-751.
View/Download from: Publisher's site
View description>>
FeS-coated iron (Fe/FeS) magnetic nanoparticles were easily prepared, characterized, and applied for Cr(VI) removal in simulated groundwater. TEM, XRD, and BET characterization tests showed that FeS coating on the surface of Fe0 inhibited the aggregation of Fe0 and that Fe/FeS at a S/Fe molar ratio of 0.207 possessed a large surface area of 62.1m2/g. Increasing the S/Fe molar ratio from 0 to 0.138 decreased Cr(VI) removal by 42.8%, and a further increase to 0.207 enhanced Cr(VI) removal by 63% within 72h. Moreover, Fe/FeS inhibited the leaching of Fe, reducing the toxicity of the particles. Mechanistic analysis indicated that Fe0, Fe2+, and S2- were synergistically involved in the reduction of Cr(VI) to nontoxic Cr(III), which further precipitated as (CrxFe1-x)(OH)3 and Cr(III)-Fe-S. The process of Cr(VI) sorption by Fe/FeS (S/Fe=0.207) was fitted well with a pseudo-second-order kinetic model, and the isotherm data were simulated by Langmuir isotherm model with a maximum sorption capacity of 69.7mg/g compared to 48.9mg/g for Fe0. Low pH and initial Cr(VI) concentration favored Cr(VI) removal. Continuous fixed bed column studies showed that simulated permeable reactive barriers (PRB) with Fe/FeS was considerably effective for in situ removal of Cr(VI) from groundwater. This study demonstrated the high potential of Fe/FeS for Cr(VI) immobilization in water, groundwater, and soil.
Gopinadhan, M, Choo, Y, Kawabata, K, Kaufman, G, Feng, X, Di, X, Rokhlenko, Y, Mahajan, LH, Ndaya, D, Kasi, RM & Osuji, CO 2017, 'Controlling orientational order in block copolymers using low-intensity magnetic fields', Proceedings of the National Academy of Sciences, vol. 114, no. 45, pp. E9437-E9444.
View/Download from: Publisher's site
View description>>
Significance Magnetic field interactions with condensed matter can produce orientationally ordered states that are important for fundamental research and technological applications. Block copolymer (BCP) mesophases typically exhibit weak field coupling, requiring high-intensity fields generated by superconducting magnets to produce such states. This work advances a strategy for circumventing such field intensity limitations and creates highly aligned mesophases using fields an order of magnitude smaller than typically required and that can be produced by simple permanent magnets. We elucidate the roles of molecular mobility, grain size, and ordering kinetics on the mesophase field response. Low-intensity field-directed BCP ordering has potentially profound implications for processing functional materials and developing complex textures by field shaping.
Grant, MJ & Stewart, MG 2017, 'Benefit of Distributed Security Queuing for Reducing Risks Associated With Improvised Explosive Device Attacks in Airport Terminals', ASCE-ASME Journal of Risk and Uncertainty in Engineering Systems, Part B: Mechanical Engineering, vol. 3, no. 2.
View/Download from: Publisher's site
View description>>
Abstract Brussels Airport ceased operations for 12 days after a coordinated improvised explosive device (IED) attack by suicide bombers in March 2016, demonstrating that critical transport hubs can be disrupted for significant durations by terrorists. Designers of critical infrastructure need to consider countermeasures to such attacks, reducing a target's attractiveness and improving opportunities for business continuity. This can be achieved by considering the cost–benefit of potential countermeasures during the design phase for infrastructure. This paper uses a probabilistic risk assessment (PRA) model for IED attack to assess the costs and benefits of using distributed security queuing at airport terminals. Our results demonstrate that the use of distributed security queuing will offer casualty reductions when used in preference to centralized security queuing. However, when considering the cost–benefit of introducing distributed security queuing, on the basis of a single small to medium IED attack, it is likely that implementing this countermeasure would not be deemed cost-effective from a purely financial perspective, particularly when the threat likelihood is very low.
Grant, MJ & Stewart, MG 2017, 'Modelling improvised explosive device attacks in the West – Assessing the hazard', Reliability Engineering & System Safety, vol. 165, pp. 345-354.
View/Download from: Publisher's site
View description>>
Improvised Explosive Devices (IEDs) continue to be a terrorist weapon of choice. With increasing pressures on the economies of Western nations, spending on counter-terrorism is subject to greater scrutiny. Homeland security agencies are no longer exempt from government fiscal due diligence, needing to justify how their spending achieves best value-for-money. Probabilistic Risk Assessment (PRA) is a valuable tool that can assist in this endeavour. This paper introduces a PRA model that characterises IED attacks in Western nations, and can be used to assess the risk reduction associated with IED attack countermeasures. When using the model with the START open-source terrorism database we identified that current IED attack countermeasures provide a risk reduction of at approximately 22%, and that terrorists using IEDs in Western nations cannot generally be considered adaptive, with the operational effectiveness of terrorists being approximately 7%.
Gu, X, Yu, Y, Li, J & Li, Y 2017, 'Semi-active control of magnetorheological elastomer base isolation system utilising learning-based inverse model', Journal of Sound and Vibration, vol. 406, pp. 346-362.
View/Download from: Publisher's site
View description>>
© 2017 Magnetorheological elastomer (MRE) base isolations have attracted considerable attention over the last two decades thanks to its self-adaptability and high-authority controllability in semi-active control realm. Due to the inherent nonlinearity and hysteresis of the devices, it is challenging to obtain a reasonably complicated mathematical model to describe the inverse dynamics of MRE base isolators and hence to realise control synthesis of the MRE base isolation system. Two aims have been achieved in this paper: i) development of an inverse model for MRE base isolator based on optimal general regression neural network (GRNN); ii) numerical and experimental validation of a real-time semi-active controlled MRE base isolation system utilising LQR controller and GRNN inverse model. The superiority of GRNN inverse model lays in fewer input variables requirement, faster training process and prompt calculation response, which makes it suitable for online training and real-time control. The control system is integrated with a three-storey shear building model and control performance of the MRE base isolation system is compared with bare building, passive-on isolation system and passive-off isolation system. Testing results show that the proposed GRNN inverse model is able to reproduce desired control force accurately and the MRE base isolation system can effectively suppress the structural responses when compared to the passive isolation system.
Guadie, A, Tizazu, S, Melese, M, Guo, W, Ngo, HH & Xia, S 2017, 'Biodecolorization of textile azo dye using Bacillus sp. strain CH12 isolated from alkaline lake', Biotechnology Reports, vol. 15, pp. 92-100.
View/Download from: Publisher's site
View description>>
© 2017 The Authors Textile azo dye decolorizing bacteria were isolated from alkaline Lakes Abaya and Chamo using Reactive Red 239 (RR239) dye. Through subsequent screening process, strain CH12 was selected to investigate the effects of nutrient supplement, DO, pH, temperature, dye concentration and types on decolorization. Based on 16S rRNA gene sequence analysis, strain CH12 was identified as Bacillus sp. Decolorization efficiencies were significantly enhanced with carbon (≥98%) and organic nitrogen (∼100%) supplements. Complete decolorization was also observed under anoxic and anaerobic conditions, and at the temperature of 30 °C and the pH of 10. However, the azo dye decolorization efficiency of strain CH12 was significantly reduced when NaNO 3 (1–8%) was supplemented or under aerobic culturing condition (≤6%), indicating that RR239 was less preferred electron acceptor. Overall, strain CH12 can be a promising candidate for decolorization applications due to its potential to effectively decolorize higher RR239 concentrations (50−250 mg/L) and six additional dyes.
Gulzar, M, Masjuki, HH, Alabdulkarem, A, Kalam, MA, Varman, M, Zulkifli, NWM, Zahid, R & Yunus, R 2017, 'Chemically active oil filter to develop detergent free bio-based lubrication for diesel engine', Energy, vol. 124, pp. 413-422.
View/Download from: Publisher's site
Gulzar, M, Masjuki, HH, Kalam, MA, Varman, M, Zulkifli, NWM, Mufti, RA, Zahid, R & Yunus, R 2017, 'Dispersion Stability and Tribological Characteristics of TiO2/SiO2 Nanocomposite-Enriched Biobased Lubricant', Tribology Transactions, vol. 60, no. 4, pp. 670-680.
View/Download from: Publisher's site
View description>>
The stable dispersion of nano-additives is highly desirable for the effective lubrication performance of nanolubricants. The compatibility of base oil with selected nano-additives is required for uniform and stable dispersion. This research evaluated the dispersion stability and tribological characteristics of nano-TiO2/SiO2 (average particle size 50 nm) as an additive in a biobased lubricant. The wear protection and friction reducing characteristics of the formulations were evaluated by four-ball extreme pressure tests and piston ring–cylinder liner sliding tests. Surface analysis tools, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy, were used to characterize the worn surfaces. Results showed that the nanolubricants demonstrated appreciable dispersion capability in the absence of a surfactant and an improvement in load-carrying capacity, antiwear behavior, and friction reduction capability.
Guo, J, Ni, B-J, Han, X, Chen, X, Bond, P, Peng, Y & Yuan, Z 2017, 'Data on metagenomic profiles of activated sludge from a full-scale wastewater treatment plant', Data in Brief, vol. 15, pp. 833-839.
View/Download from: Publisher's site
View description>>
© 2017 The Authors The data in this article mainly present the sequences of activated sludge from a full-scale municipal wastewater treatment plant (WWTP) carrying out simultaneous nitrogen and phosphorous removal in Beijing, China. Data include the operational conditions and performance, dominant microbes and taxonomic analysis in this WWTP, and function annotation results based on SEED, Clusters of Orthologous Groups (COG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Sequencing data were generated by using Illumina HiSeq. 2000 platform according to the recommendations of the manufacturer. The sequencing data have been deposited in MG-RAST server (project ID: mgm4735473.3). For more information, see “Unraveling microbial structure and diversity of activated sludge in a full-scale simultaneous nitrogen and phosphorus removal plant using metagenomic sequencing” by Guo et al. (2017) [1].
Guo, J, Ni, B-J, Han, X, Chen, X, Bond, P, Peng, Y & Yuan, Z 2017, 'Unraveling microbial structure and diversity of activated sludge in a full-scale simultaneous nitrogen and phosphorus removal plant using metagenomic sequencing', Enzyme and Microbial Technology, vol. 102, pp. 16-25.
View/Download from: Publisher's site
View description>>
© 2017 Activated sludge contains highly complex microbial communities, which play crucial roles in pollutant removal performance in wastewater treatment plants (WWTPs). Metagenomic sequencing was applied to characterize microbial community and functional profiles within activated sludge from a full-scale municipal WWTP carrying out simultaneous nitrogen and phosphorous removal (SNPR). We applied the assembled contigs (N90 of 591 bp) and predicted genes to conduct taxonomic and function annotations, respectively. Results revealed the extraordinary microbial diversity of activated sludge, which included detection of minority populations that are difficult to be explored by traditional molecular methods. Taxonomic analysis indicated that the dominant bacterial phyla were Proteobacteria, Nitrospirae, Bacteroidetes, Actinobacteria and Firmicutes. The abundance of the key organisms involved in nitrogen and phosphorous removal were qualified. Aerobic ammonia-oxidizing bacteria distinctly dominate over ammonia-oxidizing archaea and anaerobic ammonium oxidation bacteria. Various key enzymes involved in the global nitrogen cycle were annotated in the activated sludge. High abundance of the known polyphosphate accumulating organisms was detected (approximately 4.89% of the overall population reads), supporting good phosphorous removal performance. This study provides a comprehensive insight into the community structure and diversity of the SNPR system, and will provide foundation for optimal operation of nutrient removal systems.
Hanif, M, Mahlia, TMI, Aditiya, HB & Abu Bakar, MS 2017, 'Energy and environmental assessments of bioethanol production from Sri Kanji 1 cassava in Malaysia', Biofuel Research Journal, vol. 4, no. 1, pp. 537-544.
View/Download from: Publisher's site
View description>>
© 2017 BRTeam. According to the Malaysia's biofuel policy, renewable fuels are crucial for energy sustainability in the transportation sector in the future. This study was aimed to evaluate the potential of bioethanol production from Sri Kanji 1 cassava in Malaysia in terms of energy efficiency and renewability, as well to estimate the potential greenhouse gas (GHG) emissions reduction in CO2 equivalent. Bioethanol production process from cassava includes cassava farming, ethanol production, and transportation in which the primary energy consumption was considered. The Net Energy Balance (NEB) and Net Energy Ratio (NER) of 25.68 MJ/L and 3.98, respectively, indicated that bioethanol production from Sri Kanji 1 cassava in Malaysia was energy efficient. From the environmental perspective, the GHG balance results revealed that the production and distribution of 1 L of Cassava Fuel Ethanol (CFE) could reduce GHG emissions by 73.2%. Although found promising in the present study, Sri Kanji 1 cassava as bioethanol feedstock should be further investigated by constructing an actual ethanol plant to obtain real life data.
He, X, Cai, G, Zhao, C & Sheng, D 2017, 'On the stress-force-fabric equation in triaxial compressions: Some insights into the triaxial strength', Computers and Geotechnics, vol. 85, pp. 71-83.
View/Download from: Publisher's site
View description>>
The strength of granular materials during triaxial compression is investigated via a grain scale analysis in this paper. A 3D Discrete Element Method (DEM) program provides the triaxial strength data and helps to validate the micromechanical analysis. Some standard methods in statistics are employed first to quantitatively examine the assumptions made when deriving the stress-force-fabric (SFF) equation. After careful validation, a more concise format for the SFF equation is proposed for triaxial compressions. With this SFF equation, the strength is found to be jointly contributed by the magnitudes of the contact force anisotropy and fabric anisotropy. The influence of the initial void ratio, confining pressure and loading direction on the development of contact force anisotropy and fabric anisotropy is examined and presented. With similar techniques, the “force” term in the SFF equation is further decoupled, and an equation is obtained such that it explicitly links the contact force term with the friction coefficient between grains, a tensor defined as a statistic of the normal contact forces and a tensor defined as a statistic of the mobilisation status of contacts. Based on this equation, another equation regarding the stress ratio of granular assembly is obtained, and it clearly indicates two sources that contribute to the phenomenological friction nature of granular assembly. These two sources are caused by the contact force at the grain scale. The first is the anisotropy of the average normal contact forces, and the second is the mobilisation of contacts.
He, Z, Teng, J, Zhang, S & Sheng, D 2017, 'Moisture transfer and phase change in unsaturated soils: an experimental study of two types of canopy effect', SCIENCES IN COLD AND ARID REGIONS, vol. 9, no. 3, pp. 243-249.
View/Download from: Publisher's site
Henderson, IEJ, Zhu, XQ, Uy, B & Mirza, O 2017, 'Dynamic behaviour of steel-concrete composite beams retrofitted with various bolted shear connectors', Engineering Structures, vol. 131, pp. 115-135.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd In structural engineering, composite construction has become increasingly widespread due to the improvement of mechanical properties it provides. Retrospective application of the composite construction principle to old structures may be beneficial. Many end of life structures are decommissioned and replaced. If the structural integrity of old structures could be improved their service life may be extended. Recently research on the development of post-installed or retrofitted shear connectors has been conducted. Most of the research in this area is concerned with modified versions of welded shear studs or various threaded rod and nut configurations, and refer to only one type of shear connector. Therefore, the suitability of the proposed models across differing shear connection types is unknown. An experimental study has been undertaken to ascertain the differences in dynamic behaviour of cast-in and retrofitted shear connectors using a series of identical steel-concrete composite beams with various shear connection systems. Two blind bolt connector types were used as shear connection systems in steel-concrete composite beams alongside a welded shear stud specimen in both cast-in and retrofitted configurations. A finite element model was then developed. The nature of changes in dynamic behaviour due to damage were investigated using the finite element model. It was found that at increased loading the behaviour of the cast-in and retrofitted connectors was fundamentally different due to the retrofitting procedure.
Ho, L & Fatahi, B 2017, 'Axisymmetric Consolidation in Unsaturated Soil Deposit Subjected to Time-Dependent Loadings', International Journal of Geomechanics, vol. 17, no. 2, pp. 04016046-04016046.
View/Download from: Publisher's site
View description>>
© 2016 American Society of Civil Engineers. This paper presents an analytical solution to predict the axisymmetric consolidation in unsaturated soil deposits subjected to different time-dependent loadings. The mathematical procedure uses the separation of variables and Laplace transformation methods to obtain the final solution. A set of polar governing equations of flow are obtained and presented under the partial differential equations (PDEs), and then the variable separation technique is used to alter the PDEs to ordinary differential equations (ODEs) consisting of distinctive variables. Fourier Bessel and sine series are used to present functions of radial and vertical flows, respectively, and the Laplace transformation is used to obtain a function of time. Four primary time-dependent loading functions, including ramping, asymptotic, sinusoid, and damped sine wave, are mathematically simulated and incorporated into the proposed solutions. This study investigates changes in excess pore-air and pore-water pressures as well as consolidation settlement against the air-to-water permeability ratio and various loading parameters. Moreover, changes in suction and net stress induced by ramped and asymptotic loadings are also presented in the worked examples.
Hong, H, Chen, W, Xu, C, Youssef, AM, Pradhan, B & Tien Bui, D 2017, 'Rainfall-induced landslide susceptibility assessment at the Chongren area (China) using frequency ratio, certainty factor, and index of entropy', Geocarto International, vol. 32, no. 2, pp. 1-16.
View/Download from: Publisher's site
View description>>
© 2016 Taylor & Francis. The main objective of the study was to evaluate and compare the overall performance of three methods, frequency ratio (FR), certainty factor (CF) and index of entropy (IOE), for rainfall-induced landslide susceptibility mapping at the Chongren area (China) using geographic information system and remote sensing. First, a landslide inventory map for the study area was constructed from field surveys and interpretations of aerial photographs. Second, 15 landslide-related factors such as elevation, slope, aspect, plan curvature, profile curvature, stream power index, sediment transport index, topographic wetness index, distance to faults, distance to rivers, distance to roads, landuse, NDVI, lithology and rainfall were prepared for the landslide susceptibility modelling. Using these data, three landslide susceptibility models were constructed using FR, CF and IOE. Finally, these models were validated and compared using known landslide locations and the receiver operating characteristics curve. The result shows that all the models perform well on both the training and validation data. The area under the curve showed that the goodness-of-fit with the training data is 79.12, 80.34 and 80.42% for FR, CF and IOE whereas the prediction power is 80.14, 81.58 and 81.73%, for FR, CF and IOE, respectively. The result of this study may be useful for local government management and land use planning.
Hong, H, Liu, J, Zhu, A-X, Shahabi, H, Pham, BT, Chen, W, Pradhan, B & Bui, DT 2017, 'A novel hybrid integration model using support vector machines and random subspace for weather-triggered landslide susceptibility assessment in the Wuning area (China)', Environmental Earth Sciences, vol. 76, no. 19, pp. 1-19.
View/Download from: Publisher's site
View description>>
This study proposed a hybrid modeling approach using two methods, support vector machines and random subspace, to create a novel model named random subspace-based support vector machines (RSSVM) for assessing landslide susceptibility. The newly developed model was then tested in the Wuning area, China, to produce a landslide susceptibility map. With the purpose of achieving the objective of the study, a spatial dataset was initially constructed that includes a landslide inventory map consisting of 445 landslide regions. Then, various landslide-influencing factors were defined, including slope angle, aspect, altitude, topographic wetness index, stream power index, sediment transport index, soil, lithology, normalized difference vegetation index, land use, rainfall, distance to roads, distance to rivers, and distance to faults. Next, the result of the RSSVM model was validated using statistical index-based evaluations and the receiver operating characteristic curve approach. Then, to evaluate the performance of the suggested RSSVM model, a comparison analysis was performed to other existing approaches such as artificial neural network, Naïve Bayes (NB) and support vector machine (SVM). In general, the performance of the RSSVM model was better than the other models for spatial prediction of landslide susceptibility. The AUC results of the applied models are as follows: RSSVM (AUC = 0.857), followed by MLP (AUC = 0.823), SVM (AUC = 0.814) and NB (AUC = 0.783). The present study indicates that RSSVM can be used for landslide susceptibility evaluation, and the results are very useful for local governments and people living in the Wuning area.
Hong, H, Pradhan, B, Bui, DT, Xu, C, Youssef, AM & Chen, W 2017, 'Comparison of four kernel functions used in support vector machines for landslide susceptibility mapping: a case study at Suichuan area (China)', Geomatics, Natural Hazards and Risk, vol. 8, no. 2, pp. 544-569.
View/Download from: Publisher's site
View description>>
Suichuan is a mountainous area at the Jiangxi province in Central China, where rainfall-induced landslides occur frequently. The purpose of this study is to assess landslide susceptibility of this region using support vector machine (SVM) with four kernel functions: polynomial (PL), radial basis function (RBF), sigmoid (SIG), and linear (LN). A total of 178 landslides were used to accomplish this approach, of which, 125 (70%) landslides were randomly selected for training the landslide susceptibility models, whereas the remaining 53 (30%) were used for the model validation. Fifteen landslide conditioning factors were considered including slope-angle, altitude, slope-aspect, topographic wetness index (TWI), sediment transport index (STI), stream power index (SPI), plan curvature, profile curvature, distance to rivers, distance to faults, distance to roads, precipitation, landuse, normalized difference vegetation index (NDVI), and lithology. Using the training dataset, nine landslide susceptibility models for the Suichuan area were constructed with the four kernel functions. To evaluate the performance of these models, the receiver-operating characteristic curve (ROC) and area under the curve (AUC) were used. Using the training dataset, AUC values for the SVM-PL models with six degrees PL function (1–6) are 0.715, 0.801, 0.856, 0.891, 0.919, 0.953, respectively, and for the SVM-RBF model, the SVM-SIG model, and the SVM-LN model are 0.716, 0.741, and 0.740, respectively. Using the validation dataset, AUC values for the SVM-PL models with six degrees PL function (1–6) are 0.738, 0.730, 0.683, 0.648, 0.608, and 0.598, respectively, and for the SVM-RBF model, the SVM-SIG model, and the SVM-LN model are 0.716, 0.741, and 0.740, respectively. Our results suggested that the SVM-RBF model is the most suitable for landslide susceptibility assessment for the study area.
Hong, H, Pradhan, B, Sameen, MI, Chen, W & Xu, C 2017, 'Spatial prediction of rotational landslide using geographically weighted regression, logistic regression, and support vector machine models in Xing Guo area (China)', Geomatics, Natural Hazards and Risk, vol. 8, no. 2, pp. 1997-2022.
View/Download from: Publisher's site
Hoque, MA-A, Phinn, S & Roelfsema, C 2017, 'A systematic review of tropical cyclone disaster management research using remote sensing and spatial analysis', Ocean & Coastal Management, vol. 146, pp. 109-120.
View/Download from: Publisher's site
Hoque, MA-A, Phinn, S, Roelfsema, C & Childs, I 2017, 'Tropical cyclone disaster management using remote sensing and spatial analysis: A review', International Journal of Disaster Risk Reduction, vol. 22, pp. 345-354.
View/Download from: Publisher's site
Hossain, N, Haji Zaini, J & Mahlia, TMI 2017, 'A Review of Bioethanol Production from Plant-based Waste Biomass by Yeast Fermentation', International Journal of Technology, vol. 8, no. 1, pp. 5-5.
View/Download from: Publisher's site
View description>>
© IJTech 2017. Commercialization of bioethanol has recently intensified due to its market stability, low cost, sustainability, alternative fuel energy composition, greener output and colossal fossil fuel depletion. Recently, because of greenhouse intensity worldwide, many researches are ongoing to reprocess the waste as well as turning down the environmental pollution. With this scenario, the invention of bioethanol was hailed as a great accomplishment to transform waste biomass to fuel energy and in turn reduce the massive usages of fossil fuels. In this study, our review enlightens various sources of plant-based waste feed stocks as the raw materials for bioethanol production because they do not adversely impact the human food chain. However, the cheapest and conventional fermentation method, yeast fermentation is also emphasized here notably for waste biomass-to-bioethanol conversion. Since the key fermenting agent, yeast is readily available in local and international markets, it is more cost-effective in comparison with other fermentation agents. Furthermore, yeast has genuine natural fermentation capability biologically and it produces zero chemical waste. This review also concerns a detailed overview of the biological conversion processes of lignocellulosic waste biomass-to-bioethanol, the diverse performance of different types of yeasts and yeast strains, plusbioreactor design, growth kinetics of yeast fermentation, environmental issues, integrated usages on modern engines and motor vehicles, as well as future process development planning with some novel co-products.
Hossain, N, Jalil, R, Mahlia, TMI & Zaini, J 2017, 'Calorific Value Analysis of Azadirachta Excelsa and Endospermum Malaccense as Potential Solid Fuels Feedstock', International Journal of Technology, vol. 8, no. 4, pp. 634-634.
View/Download from: Publisher's site
View description>>
© IJTech 2017. Thermal conversion of woody biomass to fuel has been intensified in recent decades due to the depletion of fossil fuels, greenhouse effect and high energy demand worldwide. Screening the potential feedstock is being considered as one of the alternatives to identifying the most suitable biomass resources prior to being converted into renewable energy in the form of solid fuels, such as charcoal and briquettes. Generally, high calorific value (CV) indicates high potential of feedstock for briquettes, torrefied wood and coal generation. In this study, CV was characterized using a bomb calorimeter that was based on 3 different ranges of moisture content (MC) that are > 25%, 20%-25% and < 20% for two tropical tree species, namely Azadirachta excelsa (Sentang) and Endospermum malaccense (Sesenduk), respectively. This standard method for the characterization process was considered to determine the CV. Average CV for both samples ranged between 16-17 MJ/kg. The highest CV was 17.3490 MJ/kg and 17.1273 MJ/kg for Sesenduk and Sentang, respectively and calorific values were obtained at MC less than 20%. The experimental study demonstrated that the decreasing value of MC has increased the CV because of the high value of oxygen-to-carbon (O/C) ratio in the wood; additionally, the energy density of the wood sample was also improved when CV increased. Both of these species were proved to contain the potential of being feedstock as wood fuel resources, since they carry standard CVs, obtain fast growth with suitable conditions in Malaysia and are grown at very low cost of production for plantations, fertilizer, pesticides, labor, transportation and handling.
Hou, P, Cai, Y, Cheng, X, Zhang, X, Zhou, Z, Ye, Z, Zhang, L, Li, W & Shah, SP 2017, 'Effects of the hydration reactivity of ultrafine magnesium oxide on cement-based materials', Magazine of Concrete Research, vol. 69, no. 22, pp. 1135-1145.
View/Download from: Publisher's site
View description>>
The size of magnesium oxide may greatly affect its behaviour in cement-based materials (CBMs), and this has not been fully investigated. The reactivity of ultrafine magnesium oxide (UFM) of size 40 nm to 20 μm was assessed, and its effects on the compressive strength and volume stability of cement mortar were investigated. The results showed that the hydration of UFM followed the first-order reaction mode in the first 3 d and then slowed down due to the alteration of the reaction to the diffusion-controlled mode. UFM contributed to an increase in compressive strength and a decrease in shrinkage of CBMs at the very early age, but hindered the hydration of cement at later ages, coarsened the microstructure, and decreased the later-age shrinkage to a much smaller extent than normal light-burnt magnesium oxide. The relatively high hydration reactivity of UFM may contribute to the formation of a more compact gel structure around cement particles at the very early age, which may hinder the reaction of cement at later ages, thus leading to the slowed property gain of CBMs at later ages. The findings from this study may help in the selection of magnesium oxide types for achieving a desired CBM with certain properties.
Hu, Y, Wang, XC, Sun, Q, Ngo, HH, Yu, Z, Tang, J & Zhang, Q 2017, 'Characterization of a hybrid powdered activated carbon-dynamic membrane bioreactor (PAC-DMBR) process with high flux by gravity flow: Operational performance and sludge properties', Bioresource Technology, vol. 223, pp. 65-73.
View/Download from: Publisher's site
View description>>
Three PAC-DMBRs were developed for wastewater treatment under different PAC dosages with biomass concentrations averaged at 2.5, 3.5 and 5.0g/L. The DMBRs could be continuously operated at 40-100L/m(2)h, while higher fluxes were obtained within the PAC-DMBRs with hydraulic retention times varying in 4-10h. A dose of 1g/L PAC brought about obvious improvement in the sludge particle size distribution, settling, flocculating and dewatering properties due to the formation of biological PAC, and the sludge properties were further improved at a higher PAC dose (3g/L). The addition of PAC notably shortened the DM formation time after air backwashing and enhanced pollutant removal. Moreover, under a long solid retention time (approximately 150d), the concentrations of both soluble and bound extracellular polymeric substances (EPS) decreased substantially because of the adsorption and biodegradation effects of the biological PAC. No obvious impact on biomass activity was observed with PAC addition.
Hu, Y, Yang, Y, Wang, XC, Hao Ngo, H, Sun, Q, Li, S, Tang, J & Yu, Z 2017, 'Effects of powdered activated carbon addition on filtration performance and dynamic membrane layer properties in a hybrid DMBR process', Chemical Engineering Journal, vol. 327, pp. 39-50.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. A powdered activated carbon-dynamic membrane bioreactor (PAC-DMBR) was developed and used to treat domestic wastewater by dosing with 3 g/L PAC. The experimental results were compared with those of a control DMBR to investigate the filtration performance and various properties of the dynamic membrane (DM) layer. One flat-sheet DM module made of nylon mesh (pore size 75 μm) was used for effluent production at a high stable flux (50–100 L/m 2 h) under a 10 cm water head by gravity flow, resulting in continuous operation cycles of 60–120 h. During the operation period, the PAC-DMBR showed enhanced removal efficiency of pollutants, higher stable membrane flux (10 L/m 2 h more), lower filtration resistance (6.0–8.0 × 10 10 m −1 ), quicker formation of the DM layer (within 5 min), and better DM layer regeneration after air backwashing. The DM layer in the PAC-DMBR showed a more porous and incompressible structure, because less extracellular polymeric substance and a portion of the biological PAC were incorporated into the DM layer formed as verified by the analytical results. Using high-throughput pyrosequencing technology, it was revealed that at the genus level the diversity of bacterial communities increased from 18 to 23 genera, while several genera that were favored in the PAC-assisted environment or were responsible for degrading complex organics were enriched. Moreover, the abundance of phylum Proteobacteria, which served as pioneer surface colonizers, was reduced in the PAC-DMBR. It was concluded that PAC addition could modify various aspects of the activated sludge and the DM layer properties, which affected the filtration behavior of the DM layer in the PAC-DMBR.
Huang, M, Ouyang, L, Chen, Z, Peng, C, Zhu, X & Zhu, M 2017, 'Hydrogen production via hydrolysis of Mg-oxide composites', International Journal of Hydrogen Energy, vol. 42, no. 35, pp. 22305-22311.
View/Download from: Publisher's site
Huang, M, Ouyang, L, Liu, J, Wang, H, Shao, H & Zhu, M 2017, 'Enhanced hydrogen generation by hydrolysis of Mg doped with flower-like MoS 2 for fuel cell applications', Journal of Power Sources, vol. 365, pp. 273-281.
View/Download from: Publisher's site
Imdadul, HK, Masjuki, HH, Kalam, MA, Zulkifli, NWM, Kamruzzaman, M, Shahin, MM & Rashed, MM 2017, 'Evaluation of oxygenated n-butanol-biodiesel blends along with ethyl hexyl nitrate as cetane improver on diesel engine attributes', Journal of Cleaner Production, vol. 141, pp. 928-939.
View/Download from: Publisher's site
Imdadul, HK, Rashed, MM, Shahin, MM, Masjuki, HH, Kalam, MA, Kamruzzaman, M & Rashedul, HK 2017, 'Quality improvement of biodiesel blends using different promising fuel additives to reduce fuel consumption and NO emission from CI engine', Energy Conversion and Management, vol. 138, pp. 327-337.
View/Download from: Publisher's site
Imdadul, HK, Zulkifli, NWM, Masjuki, HH, Kalam, MA, Kamruzzaman, M, Rashed, MM, Rashedul, HK & Alwi, A 2017, 'Experimental assessment of non-edible candlenut biodiesel and its blend characteristics as diesel engine fuel', Environmental Science and Pollution Research, vol. 24, no. 3, pp. 2350-2363.
View/Download from: Publisher's site
Indraratna, B & Sun, Y 2017, 'Closure to “Laboratory Assessment of the Role of Particle Size Distribution on the Deformation and Degradation of Ballast under Cyclic Loading” by Buddhima Indraratna, Yifei Sun, and Sanjay Nimbalkar', Journal of Geotechnical and Geoenvironmental Engineering, vol. 143, no. 9, pp. 07017023-07017023.
View/Download from: Publisher's site
Indraratna, B, Baral, P, Ameratunga, J & Kendaragama, B 2017, 'Potential biological and chemical clogging of piezometer filters in acid sulphate soil', Australian Geomechanics Journal, vol. 52, no. 2, pp. 79-85.
View description>>
Instrumentation for performance monitoring of an embankment built on soft soils is vital for assessing the progress of consolidation and confirming (or refuting) soil parameters used in design when there are significant design uncertainties and the monitoring data can be used to calibrate the design soil parameters. A suite of instruments including settlement plates, extensometers, piezometers, inclinometers is often employed for this purpose. In the first Author's experience, erroneous readings interpretations of pore water pressure (PWP) readings have been reported in various case studies involving transport infrastructure development and reclamations works both in Australia and South East Asia, especially in low-lying acid sulphate soil floodplains. It has been observed that in spite of the presence of vertical drains (PVDs), excess pore water pressure readings from vibrating wire piezometers (VWPs) do not always dissipate as fast as expected especially after a certain period of time, typically a year. The article discusses the potential factors affecting the reliability of VWPs including filter tip clogging, extreme smearing of soil adjoining the filter, gas generation or cavitation, chemical alteration or corrosion of the filter, electro-osmotic effects and cavitation due to bacterial activity. Based on this, the response of VWPs may be divided into a distinct trilinear trend, observed for much of the Australian northern and eastern coastal belt that is predominantly affected by Acid sulphate soil (ASS) conditions where oxidisable pyrite layers are present within relatively shallow depths of the upper Holocene clay.
Indraratna, B, Ngo, NT & Rujikiatkamjorn, C 2017, 'Improved Performance of Ballasted Rail Tracks Using Plastics and Rubber Inclusions', Procedia Engineering, vol. 189, pp. 207-214.
View/Download from: Publisher's site
View description>>
Current railroads require significant upgrading to meet the challenges of heavier loads at higher speeds. Due to excessive track degradation, the Australian rail industry spends large amounts on frequent track repair and maintenance, as well as ground improvement prior to track construction where soft and saturated subgrade soils pose considerable difficulties in design and construction. Moreover, the degradation of ballast particles under impact loading seriously hampers the safety and efficiency of rail tracks, which leads to speed restrictions and more frequent track upgrading. Hence, there is a need for innovative design solutions that can extend the service life of tracks to cater for faster and heavier train traffic. The use of planar geosynthetics and recycled rubber mats placed at the interface of ballast and subballast layer has proven an effective approach to mitigate ballast degradation and improve track longevity. This paper presents the current state-of-the-art knowledge of rail track geomechanics conducted at the University of Wollongong (UOW) including topics relating to laboratory testing and computational modeling approaches. The load-deformation responses of rubber mat/geogrid-stabilised ballast are studied in the laboratory using a large-scale drop weight impact testing facility, and Track Process Simulation Apparatus (TPSA). Numerical modelling using discrete element methods (DEM) are used to model geogrid-reinforced ballasted tracks, capturing both the discrete nature of ballast subject to various types of loading and boundary conditions. These results provide promising approaches to incorporate into the existing track design routines catering for future high speed and heavy haul trains.
Indraratna, B, Pathirage, PU & Banasiak, LJ 2017, 'Remediation of acidic groundwater by way of permeable reactive barrier', Environmental Geotechnics, vol. 4, no. 4, pp. 284-298.
View/Download from: Publisher's site
View description>>
A permeable reactive barrier (PRB) was installed in the Shoalhaven Floodplain about 100 km south of Sydney (Australia), where acidic groundwater generation from pyritic soil poses a severe environmental and socioeconomic problem. Recycled concrete aggregates were a promising source of alkalinity-generating material and adopted as the reactive media for this PRB. The current study simulates the performance of the PRB through coupling geochemical reactions involved with recycled concrete and acidic groundwater with geohydraulics (transient groundwater flows). This is the first such attempt made for time-dependent modelling and performance verification of a PRB located in acid sulfate soil (ASS) terrain. The developed model describes the chemical clogging due to mineral precipitates and the associated reductions in porosity and hydraulic conductivity of the reactive medium. The governing equations of the model were incorporated into commercial software, MODFLOW and RT3D. The field results are in favourable agreement with the model predictions, confirming that the reduction in hydraulic conductivity due to mineral precipitation occurs predominantly at the entrance zone of the PRB and insignificantly in the middle and exit zones after 7 years of operation. Mineralogical analysis undertaken on sample specimens from the PRB also confirms that clogging is minimal at the entrance zone.
Indraratna, B, Sun, Q & Grant, J 2017, 'Behaviour of subballast reinforced with used tyre and potential application in rail tracks', Transportation Geotechnics, vol. 12, pp. 26-36.
View/Download from: Publisher's site
View description>>
Rubber tyres have a three dimensional cylindrical structure, and as such could be used to stabilise foundations by increasing the bearing capacity and reducing settlement for transport infrastructure. It is therefore expected that in railroad engineering, a capping layer reinforced with rubber tyres could help to reduce the thickness of the granular layer (i.e. ballast), improve the track bearing capacity, and reduce the frequency of maintenance. However, there is a notable gap between the conceptual theories and real-life applications pertaining to the mechanisms of rubber tyre-reinforced foundations. In pavement engineering, the bearing capacity is closely linked to plate load tests. In this study, plate load tests were carried out on a single tyre filled with subballast material and subjected to a vertical load. This testing process was then modelled using the Finite Element software ABAQUS to study and quantify the interaction between the tyre and the granular medium. The experimental and numerical results reveal that the rubber tyre can significantly increase the modulus and ultimate bearing capacity of the granular layer. The numerical process was further extended to a finite element track model to demonstrate the expected response of a ballasted railway track with and without tyre reinforcement.
Indraratna, B, Sun, Q, Ngo, NT & Rujikiatkamjorn, C 2017, 'Current research into ballasted rail tracks: model tests and their practical implications', Australian Journal of Structural Engineering, vol. 18, no. 3, pp. 204-220.
View/Download from: Publisher's site
View description>>
Ballasted rail tracks are the most important mode of transportation in terms of traffic tonnage serving the needs of bulk freight and passenger movement, but under train loads, the particles degrade due to breakage and the progressive accumulation of external fines or mud-pumping under the subgrade, all of which reduce its shear strength and increase track instability. These actions adversely affect the safety, passenger comfort and efficiency of tracks, as well as enforcing speed restrictions and more frequent track maintenance. In spite of advances in rail track geotechnology, the optimum choice of ballast for track design is still considered critical because ballast degradation is influenced by the amplitude and number of load cycles, particle gradation, track confining pressure and the angularity and fracture strength of individual grains. One of the most effective methods of enhancing track stability and reducing the stresses transmitted to a soft subgrade layer is to increase the stiffness of the overlying granular media. This paper presents our current knowledge of rail track geomechanics, including important concepts/topics related to laboratory testing and computational modelling approaches used to study the load–deformation behaviour of ballast improved with waste tyres, synthetic geogrids and geocells.
Indraratna, B, Zhong, R, Fox, PJ & Rujikiatkamjorn, C 2017, 'Large-Strain Vacuum-Assisted Consolidation with Non-Darcian Radial Flow Incorporating Varying Permeability and Compressibility', Journal of Geotechnical and Geoenvironmental Engineering, vol. 143, no. 1, pp. 04016088-04016088.
View/Download from: Publisher's site
Iranmanesh, S, Ong, HC, Ang, BC, Sadeghinezhad, E, Esmaeilzadeh, A & Mehrali, M 2017, 'Thermal performance enhancement of an evacuated tube solar collector using graphene nanoplatelets nanofluid', Journal of Cleaner Production, vol. 162, pp. 121-129.
View/Download from: Publisher's site
Islam, MR, Das, NG, Barua, P, Hossain, MB, Venkatramanan, S & Chung, SY 2017, 'Environmental assessment of water and soil contamination in Rajakhali Canal of Karnaphuli River (Bangladesh) impacted by anthropogenic influences: a preliminary case study', Applied Water Science, vol. 7, no. 2, pp. 997-1010.
View/Download from: Publisher's site
Israr, J & Indraratna, B 2017, 'Internal Stability of Granular Filters under Static and Cyclic Loading', Journal of Geotechnical and Geoenvironmental Engineering, vol. 143, no. 6, pp. 04017012-04017012.
View/Download from: Publisher's site
Jaber, HS, Mansor, S, Pradhan, B & Ahmad, N 2017, 'Rainfall–runoff modelling and water balance analysis for Al-Hindiyah barrage, Iraq using remote sensing and GIS', Geocarto International, vol. 32, no. 12, pp. 1407-1420.
View/Download from: Publisher's site
Jamshidi Chenari, R, Fatahi, B, Akhavan Maroufi, MA & Alaie, R 2017, 'An Experimental and Numerical Investigation into the Compressibility and Settlement of Sand Mixed with TDA', Geotechnical and Geological Engineering, vol. 35, no. 5, pp. 2401-2420.
View/Download from: Publisher's site
View description>>
A series of large scale oedometer experiments were carried out to investigate the settlement of sand reinforced with tire derived aggregates (TDA). The parameters studied were five different amounts of TDAs, three aspect ratios and relative skeletal densities, and seven overburden pressures. The volume compressibility coefficient was calculated against different input parameters, and the constraint condition used enabled Poisson’s ratio to be calculated from an “at-rest” coefficient of earth pressure. The triaxial modulus was calculated indirectly and then adopted in subsequent numerical analyses. Finite element analysis and Monte Carlo simulations were used to investigate the settlement of this mixture and to study how the different parameters affected the settlement mixtures of sand and TDAs. The experimental and numerical results reveal that the amount of TDAs is the major parameter which affects settlement, although the overburden pressure and relative skeletal density are also important. The aspect ratio of the shred has almost no effect on volume compressibility parameters as long as constraint compression condition governs. Two index parameters were defined to discuss the type of shred distribution and how it affects settlement of the mixture.
Jayawardhana, M, Zhu, X, Liyanapathirana, R & Gunawardana, U 2017, 'Compressive sensing for efficient health monitoring and effective damage detection of structures', Mechanical Systems and Signal Processing, vol. 84, pp. 414-430.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd Real world Structural Health Monitoring (SHM) systems consist of sensors in the scale of hundreds, each sensor generating extremely large amounts of data, often arousing the issue of the cost associated with data transfer and storage. Sensor energy is a major component included in this cost factor, especially in Wireless Sensor Networks (WSN). Data compression is one of the techniques that is being explored to mitigate the effects of these issues. In contrast to traditional data compression techniques, Compressive Sensing (CS) – a very recent development – introduces the means of accurately reproducing a signal by acquiring much less number of samples than that defined by Nyquist's theorem. CS achieves this task by exploiting the sparsity of the signal. By the reduced amount of data samples, CS may help reduce the energy consumption and storage costs associated with SHM systems. This paper investigates CS based data acquisition in SHM, in particular, the implications of CS on damage detection and localization. CS is implemented in a simulation environment to compress structural response data from a Reinforced Concrete (RC) structure. Promising results were obtained from the compressed data reconstruction process as well as the subsequent damage identification process using the reconstructed data. A reconstruction accuracy of 99% could be achieved at a Compression Ratio (CR) of 2.48 using the experimental data. Further analysis using the reconstructed signals provided accurate damage detection and localization results using two damage detection algorithms, showing that CS has not compromised the crucial information on structural damages during the compression process.
Jia, H, Yang, G, Ngo, H-H, Guo, W, Zhang, H, Gao, F & Wang, J 2017, 'Enhancing simultaneous response and amplification of biosensor in microbial fuel cell-based upflow anaerobic sludge bed reactor supplemented with zero-valent iron', Chemical Engineering Journal, vol. 327, pp. 1117-1127.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The development of a convenient and sensitive sensor such as a microbial fuel cell (MFC) to monitor the operation of upflow anaerobic sludge blanket (UASB) is indispensable. However, the biosensor's properties were affected due to excessive acidification and suffocation of the electron transport. In this study, zero-valent iron (ZVI) was applied to restrain excessive acidification and improve the sensing performance. According to the results, the response rate of electrical signal accumulated with the addition of ZVI compared to the control reactor. As well as the electrical signal amplified and the subsidence rate maximum reached 0.059 V/h with 30 mg/L ZVI added that 883% higher than the control one during the stage (COD concentration 500 mg/L–1000 mg/L). With the electrochemical analysis, the internal resistance of ZVI-UASB-MFC decreased and redox activity promoted effectively with ZVI added. During the overloading phase, the fractional content of butyric acid changed from 53% to 31%, while that of acetic acid rose from 18% to 39% after 30 mg/L ZVI addition. These results indicated that adding ZVI to the digestion could retard excessive acidification by promoting butyric acid conversion and accumulating direct interspecies electron transfer simultaneous for enhancing the biosensor's performance. According to the Fe 2+ and Fe 3+ of effluent were 2.25 mg/L and 0.39 mg/L with 50 mg/L ZVI addition, moderate amount of ZVI was effective for system and safety to the environment. It might helpfully provide a promising way to enhance biosensing.
Jiang, YB, He, N, Xu, BH, Zhou, YZ & Zhang, ZL 2017, 'Model tests on negative pressure distribution in vacuum preloading', Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering, vol. 39, no. 10, pp. 1874-1883.
View/Download from: Publisher's site
View description>>
The rule of negative pressure distribution is an important subject in the studies on vacuum preloading mechanism. By discussing the spatial distribution characteristics of vacuum preloading and the associated concepts, the negative pressure is defined in a broad sense, and the methods and influencing factors for the negative pressure measurement are analyzed. The tests are carried out, with a well-designed large scale indoor model 15 m in vertical height, to study the negative pressure distribution in vacuum preloading. The test results show that there is hysteresis effect in vacuum measurement in saturated clay soil, and the limit depth where vacuum exists is 8.9 m. The pore water pressure and vacuum degree in drain board exhibit a symmetrical linear distribution above zero pressure plane at the vacuum stable stage, and the slope is similar to hydrostatic pressure gradient. The negative pressure distribution along the depth is of piecewise linear type, due to the energy consumption in water lifting, attenuation is found in the unsaturated soil above the underground water level, and the average attenuation value is 21.4 kPa in the stable period. The negative pressure is uniform with no attenuation under the average water level, and the corresponding average negative pressure is -67.0 kPa within the depth scope of drainage board in the stable period. Based on the experimental results and the flow pattern distribution of gas-liquid two-phase flow in the equivalent drainage tube, the piecewise linear negative pressure boundary of the vertical drainage board in the stable period of vacuum preloading is put forward.
Jozi, B, Braun, R, Samali, B, Li, J & Dackermann, U 2017, 'Limitation of the Lateral Angled Broadband Low Frequency Impact Excitation on the Non-Destructive Condition Assessment of the Timber Utility Poles', International Journal of Advancements in Technology, vol. 08, no. 04, pp. 1-8.
View/Download from: Publisher's site
View description>>
Timber utility poles play a significant role in the infrastructure of Australia as well as many other countries for power distribution and communication networks. Due to the advanced age of Australia’s timber pole infrastructure, substantial efforts are undertaken on maintenance and asset management to avoid any failures of the utility lines. Nevertheless, the lack of reliable tools for assessing the condition of in-service poles seriously jeopardizes the maintenance and asset management. For instance, each year approximately 300,000 poles are replaced in the Eastern States of Australia with up to 80% of them still being in a very good condition, resulting in major waste of natural resources and money. Non-destructive testing (NDT) methods based on stress wave propagation can potentially offer simple and cost-effective tools for identifying the in-service condition of timber poles. Nonetheless, most of the currently available methods are not appropriate for condition assessment of timber poles in-service due to presence of uncertainties such as complicated material properties, environmental conditions, interaction of soil and structure, and an impact excitation type. In order to address these complexities, advanced digital signal processing methodologies are needed to be employed. Deterministic signal separation, blind signal separation, and frequency-wavenumber velocity filtering are the three groups of methodologies, which could most probably provide solutions. In this paper applicability and effectiveness of the blind signal separation methods is investigated through a numerical data obtained from of a timber pole modelled with both isotropic and orthotropic material properties. Principal Component Analysis (PCA), Singular Value Decomposition (SVD), and K-means clustering algorithms are the blind signal separation methodologies that are employed in this research work.
Jupp, J 2017, '4D BIM for Environmental Planning and Management', Procedia Engineering, vol. 180, pp. 190-201.
View/Download from: Publisher's site
View description>>
© 2017 The Authors. For more than a decade research has shown that 4D Building Information Modelling (BIM) can improve construction planning, scheduling and production control as well as the onsite management of safety, workspaces and waste. The increasing use of 4D BIM in construction highlights opportunities for utilising these capabilities in new digital management systems replete with role reorganization, new practices and workflows, and not solely as a tool for constructability analysis and onsite monitoring of construction progress. Continued focus on construction-based environmental impacts provides an impetus to leverage 4D BIM to improve communication and information flow throughout environmental planning and management tasks. This paper explores how environmental planning and management can be supported by 4D capabilities. 4D modelling and analysis technologies combined with structured workflows are presented as the basis for developing a tailored framework for environmental planning and management. Five functional prerequisites necessary to the collaborative development and onsite monitoring of environmental management systems are identified before laying out the directions for future research.
Kalam, MA, Masjuki, HH, Cho, HM, Mosarof, MH, Mahmud, MI, Chowdhury, MA & Zulkifli, NWM 2017, 'Influences of thermal stability, and lubrication performance of biodegradable oil as an engine oil for improving the efficiency of heavy duty diesel engine', Fuel, vol. 196, pp. 36-46.
View/Download from: Publisher's site
View description>>
Nowadays, the development of biodegradable products is important in improving energy efficiency and green environment, particularly in energy conservation and rotation of machinery systems. In the case of sliding components, lubrication system and lubricant quality plays an important role for energy efficiency as it is directly involved with frictional force and components wear characteristics. The conventional mineral oil-based lubricant is used for machinery lubrications; however, it is nonbiodegradable and is an environmental pollutant. This investigation attempts to develop biolubricant acquired from various vegetable oils to replace mineral oil-based lubricants. This study evaluates the physicochemical properties, thermal stability, and lubricating and tribological characteristics of olive oil and its comparative analysis with commercial lube oil. A four-ball tribotester was used to measure the friction and wear properties of the sample according to the ASTM 4172 method. Olive oil has an excellent oxidation stability due to the presence of high percentages of oleic acid in fatty acid composition. Olive oil showed higher viscosity index and kinematic viscosity than other vegetable oils; hence, it is better for boundary lubrication. Thermogravimetric analysis showed that olive oil persists thermally steady up to 390 °C. Olive oil showed a lower coefficient of friction, wear scar diameter, and worn scar surface area than commercial lube oil. Therefore, due to the better lubricating performance, olive oil has high potential for use as an engine lubricating oil for improving efficiency of heavy-duty engines in the automotive applications.
Kalantar, B, Mansor, SB, Sameen, MI, Pradhan, B & Shafri, HZM 2017, 'Drone-based land-cover mapping using a fuzzy unordered rule induction algorithm integrated into object-based image analysis', International Journal of Remote Sensing, vol. 38, no. 8-10, pp. 2535-2556.
View/Download from: Publisher's site
View description>>
© 2017 Informa UK Limited, trading as Taylor & Francis Group. Land-cover maps provide essential data for a wide range of practical and small-scale applications. A number of data sources appropriate for land-cover extraction are available. Among these, images captured using unmanned aerial vehicles (UAVs) are low cost, have very high resolution, and can be acquired at any time with few restrictions. Over the past two decades, various classification techniques have been developed to extract land-cover features from UAV images, and object-based image analysis (OBIA) is the preferred technique based on the recent literature. This study presents a novel method that integrates the fuzzy unordered rule induction algorithm (FURIA) into OBIA to achieve accurate land-cover extraction from UAV images. The images were segmented using a multiresolution segmentation algorithm with an optimized scale parameter. The scale parameter was optimized using a novel approach that integrated feature space optimization into the plateau objective function. During the classification stage, significant features were selected via random forest, and rule sets were developed using FURIA. For comparison, result of the proposed approach was compared with those of decision tree (DT) rules and the Support Vector Machine (SVM) classification method. The results of this study indicate that the proposed method outperforms DT and SVM with an overall accuracy of 91.23%. A transferability evaluation showed that FURIA achieved accurate classification results on different UAV image subsets captured at different times. The findings suggest that fuzzy rules are more appropriate than conventional crisp rules for land-cover extraction from UAV images.
Kalaruban, M, Loganathan, P, Kandasamy, J, Naidu, R & Vigneswaran, S 2017, 'Enhanced removal of nitrate in an integrated electrochemical-adsorption system', Separation and Purification Technology, vol. 189, pp. 260-266.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The electrochemical (EC) method of removing pollutants in water is a widely used process in water and wastewater treatment. An EC-adsorption integrated system was investigated to test whether the simultaneous removal of nitrate by the two processes would be better than removal utilising the individual EC and adsorption methods. In the integrated system, an adsorbent (ion exchange resin - Dowex 21k XLT) was placed inside a stainless steel box that served as an anode with a Cu plate as cathode. In an experiment using 2 L nitrate solution containing 20 mg N/L and 2 g adsorbent the rate of nitrate removal in the integrated system was initially fast with 35% removed in 30 min, though slowing down later. The rate of removal increased with increasing current, voltage and pH up to 7 but decreased as the distance between the electrodes also increased. The optimum nitrate removal of 67% was obtained at pH 7, 1 A, and 31 V for a distance of 1 cm between the electrodes after 180 min. The amount of nitrate removed fell when sulphate was present in the integrated system due to sulphate competing with nitrate for adsorption. Concentration of ammonium produced by nitrate reduction in the EC system was reduced in the presence of adsorbent. Nitrate removal in the integrated system is approximately equal to the sum of the removals in the two individual processes.
Kalhori, H, Makki Alamdari, M, Zhu, X, Samali, B & Mustapha, S 2017, 'Non-intrusive schemes for speed and axle identification in bridge-weigh-in-motion systems', Measurement Science and Technology, vol. 28, no. 2, pp. 025102-025102.
View/Download from: Publisher's site
View description>>
© 2017 IOP Publishing Ltd. Bridge weigh-in-motion (BWIM) is an approach through which the axle and gross weight of trucks travelling at normal highway speed are identified using the response of an instrumented bridge. The vehicle speed, the number of axles, and the axle spacing are crucial parameters, and are required to be determined in the majority of BWIM algorithms. Nothing-on-the-road (NOR) strategy suggests using the strain signals measured at some particular positions underneath the deck or girders of a bridge to obtain this information. The objective of this research is to present a concise overview of the challenges of the current non-intrusive schemes for speed and axle determination through bending-strain and shear-strain based approaches. The problem associated with the global bending-strain responses measured at quarter points of span is discussed and a new sensor arrangement is proposed as an alternative. As for measurement of local responses rather than the global responses, the advantage of shear strains over bending strains is presented. However, it is illustrated that shear strains at quarter points of span can only provide accurate speed estimation but fail to detect the correct number of axles. As a remedy, it is demonstrated that, even for closely-spaced axles, the shear strain at the beginning of the bridge is capable of reliably identifying the number of axles. In order to provide a fully automated speed and axle identification system, appropriate signal processing including low-pass filtering and wavelet transforms are applied to the raw time signals. As case studies, the results of experimental testing in laboratory and on a real bridge are presented.
Kang, Y, Zhang, J, Xie, H, Guo, Z, Ngo, HH, Guo, W & Liang, S 2017, 'Enhanced nutrient removal and mechanisms study in benthic fauna added surface-flow constructed wetlands: The role of Tubifex tubifex', Bioresource Technology, vol. 224, pp. 157-165.
View/Download from: Publisher's site
View description>>
This study designed a combined benthic fauna-T. orientalis-substrate-microbes surface-flow constructed wetlands (SFCWs) through the addition of T. tubifex. Results showed that, the removal efficiencies of nitrogen and phosphorus in the tested SFCWs achieved 81.14±4.16% and 70.49±7.60%, which were 22.27% and 27.35% higher than that without T. tubifex. Lower nitrate (2.11±0.79mg/L) and ammonium (0.75±0.64mg/L) were also observed in the tested SFCWs, which were 3.46mg/L and 0.52mg/L lower than that without T. tubifex. Microbial study confirmed the increased denitrifiers with T. tubifex. The lower nitrogen in effluent was also attributed to higher contents of nitrogen storage in sediment and T. orientalis due to the bioturbation of T. tubifex. Furthermore, with T. tubifex, higher proportions of particulate (22.66±3.96%) and colloidal phosphorus (20.57±3.39%) observed promoted phosphorus settlement and further absorption by T. orientalis. The outcomes of this study provides an ecological and economical strategy for improving the performance of SFCWs.
Kaufman, G, Liu, W, Williams, DM, Choo, Y, Gopinadhan, M, Samudrala, N, Sarfati, R, Yan, ECY, Regan, L & Osuji, CO 2017, 'Flat Drops, Elastic Sheets, and Microcapsules by Interfacial Assembly of a Bacterial Biofilm Protein, BslA', Langmuir, vol. 33, no. 47, pp. 13590-13597.
View/Download from: Publisher's site
Keshavarzi, A & Ball, J 2017, 'Enhancing PIV image and fractal descriptor for velocity and shear stresses propagation around a circular pier', Geoscience Frontiers, vol. 8, no. 4, pp. 869-883.
View/Download from: Publisher's site
View description>>
© 2016 China University of Geosciences (Beijing) and Peking University In this study, the fractal dimensions of velocity fluctuations and the Reynolds shear stresses propagation for flow around a circular bridge pier are presented. In the study reported herein, the fractal dimension of velocity fluctuations (u′, v′, w′) and the Reynolds shear stresses (u′v′ and u′w′) of flow around a bridge pier were computed using a Fractal Interpolation Function (FIF) algorithm. The velocity fluctuations of flow along a horizontal plane above the bed were measured using Acoustic Doppler Velocity meter (ADV) and Particle Image Velocimetry (PIV). The PIV is a powerful technique which enables us to attain high resolution spatial and temporal information of turbulent flow using instantaneous time snapshots. In this study, PIV was used for detection of high resolution fractal scaling around a bridge pier. The results showed that the fractal dimension of flow fluctuated significantly in the longitudinal and transverse directions in the vicinity of the pier. It was also found that the fractal dimension of velocity fluctuations and shear stresses increased rapidly at vicinity of pier at downstream whereas it remained approximately unchanged far downstream of the pier. The higher value of fractal dimension was found at a distance equal to one times of the pier diameter in the back of the pier. Furthermore, the average fractal dimension for the streamwise and transverse velocity fluctuations decreased from the centreline to the side wall of the flume. Finally, the results from ADV measurement were consistent with the result from PIV, therefore, the ADV enables to detect turbulent characteristics of flow around a circular bridge pier.
Khallaf, M & Jupp, J 2017, 'Performance-based Design of Tall Building Envelopes using Competing Wind Load and Wind Flow Criteria', Procedia Engineering, vol. 180, pp. 99-109.
View/Download from: Publisher's site
View description>>
This paper investigates performance-based tall building design and the development of an architectural and urban design method that focus on the effects of wind loads on- and wind flows around tall buildings. The paper provides an overview of related buildings codes and city development design guidelines that define the requirements of structural façade wind loading and urban ventilation. A review of performance-based design methods for the generation, analysis and optimization of buildings is also presented. Within this frame, an approach to performancebased tall building envelope design is proposed. The approach is aimed at addressing wind loading and wind impact requirements based on generative parametric modelling and performance analysis that integrates physical parameters at the architectural and urban scales and performance criteria can support filtering and optimization relative to prevailing wind conditions.
Khan, I, Castel, A & Gilbert, RI 2017, 'Effects of Fly Ash on Early-Age Properties and Cracking of Concrete', ACI Materials Journal, vol. 114, no. 4, pp. 673-681.
View/Download from: Publisher's site
Khan, I, Castel, A & Gilbert, RI 2017, 'Tensile creep and early-age concrete cracking due to restrained shrinkage', Construction and Building Materials, vol. 149, pp. 705-715.
View/Download from: Publisher's site
View description>>
Concrete structures are prone to cracking due to restraint provided to early age autogenous and drying shrinkage. In addition, the risk of early-age thermal cracking is increased by increasing the degree of restraint to early-age thermal contraction. At this early-age, tensile creep plays a key role in relaxing shrinkage induced tensile stresses and delaying the time to cracking. However, limited data are available concerning tensile creep of concrete and the magnitude and rate of development of the early-age shrinkage of concrete. As a consequence, restraint to shrinkage is often poorly modelled in structural design. In order to accurately quantify the early-age shrinkage and tensile creep of concrete, a comprehensive experimental program is being conducted at the UNSW Centre for Infrastructure Engineering and Safety. Tensile creep is measured on dog-bone shaped specimens subjected to constant sustained tensile stress, while shrinkage is measured on identical unloaded specimens. Restrained ring tests were also performed to validate the tensile creep coefficients calculated from dog-bone specimens. A simple analytical procedure to accurately predict the degree of restraint and the tensile stresses in concrete induced by shrinkage is described for the restrained ring specimens.
Khan, MH, Jamali, SS, Lyalin, A, Molino, PJ, Jiang, L, Liu, HK, Taketsugu, T & Huang, Z 2017, 'Atomically Thin Hexagonal Boron Nitride Nanofilm for Cu Protection: The Importance of Film Perfection', Advanced Materials, vol. 29, no. 4, pp. 1-7.
View/Download from: Publisher's site
View description>>
Outstanding protection of Cu by high-quality boron nitride nanofilm (BNNF) 1-2 atomic layers thick in salt water is observed, while defective BNNF accelerates the reaction of Cu toward water. The chemical stability, insulating nature, and impermeability of ions through the BN hexagons render BNNF a great choice for atomic-scale protection.
Khan, MH, Liu, HK, Sun, X, Yamauchi, Y, Bando, Y, Golberg, D & Huang, Z 2017, 'Few-atomic-layered hexagonal boron nitride: CVD growth, characterization, and applications', Materials Today, vol. 20, no. 10, pp. 611-628.
View/Download from: Publisher's site
View description>>
© 2017 Two-dimensional (2D) materials have shown outstanding properties that make them the materials of choice for future semiconductor and flexible nanoelectronics. Hexagonal boron nitride nanosheet (BNNS) is one of the most studied 2D materials due to its extraordinary properties and potential applications. The synthesis of large, homogeneous, and few-layered BNNS, however, remains challenging. Among the various synthetic routes, chemical vapour deposition (CVD) is preferred on the grounds of its potential to yield large BNNS with controllable atomic layers and minimal contamination. We thus devote this review to the CVD growth of BNNS, and its characterization and applications. The recent progresses in the CVD growth of BNNS is firstly summarized from the aspects of precursors, substrates, growth mechanisms, and transfer techniques. This review then moves on to the characterization of few-atomic-layered h-BN sheets, covering a variety of microscopic and spectroscopic techniques that have proved useful for assessing the quality of BNNS. The applications of the BNNS are also summarized. This review is expected to instigate new methods and improvements in relation to the CVD growth of BNNS, which has enabled exceptional performance as a key component of nanoscale electronics.
Khan, MSH, Castel, A & Noushini, A 2017, 'Carbonation of a low-calcium fly ash geopolymer concrete', Magazine of Concrete Research, vol. 69, no. 1, pp. 24-34.
View/Download from: Publisher's site
View description>>
The carbonation resistance of a blended slag and low-calcium fly ash (FA) geopolymer concrete was investigated. The geopolymer binder studied was composed of 90% low-calcium FA and 10% ground granulated blast-furnace slag. The alkalinity of the pore solution plays a pivotal role in carbonation progression and subsequent corrosion initiation. pH profiles were measured to assess the pore solution alkalinity. Phenolphthalein indicator was used to measure the carbonation depth. X-ray diffraction (XRD) and quantification were carried out to identify and quantify the carbonation products. The obtained pH profiles illustrated a wider semi-carbonation zone in the geopolymer specimens, although the pH drop was insignificant in most cases. XRD analysis revealed that nahcolite mainly formed at 3% carbon dioxide concentration and led to a significant drop in pH values. The results further demonstrated that 1% accelerated carbonation replicated the natural carbonation process well, with only natron identified as a carbonation product. This work contributes to the assessment of the risk of carbonation-induced reinforcement corrosion in low-calcium FA geopolymer concrete.
Kim, J, Blandin, G, Phuntsho, S, Verliefde, A, Le-Clech, P & Shon, H 2017, 'Practical considerations for operability of an 8″ spiral wound forward osmosis module: Hydrodynamics, fouling behaviour and cleaning strategy', Desalination, vol. 404, pp. 249-258.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. A better understanding of large spiral wound forward osmosis (SW FO) module operation is needed to provide practical insight for a full-scale FO practical implementation desalination plant. Therefore, this study investigated two different 8″ SW FO modules (i.e. cellulose tri acetate, CTA and thin film composite, TFC) in terms of hydrodynamics, operating pressure, water and solute fluxes, fouling behaviour and cleaning strategy. For both modules, a significantly lower flow rate was required in the draw channel than in the feed channel due to important pressure-drop in the draw channel and was a particularly critical operating challenge in the CTA module when permeate spacers are used. Under FO and pressure assisted osmosis (PAO, up to 2.5 bar) operations, the TFC module featured higher water flux and lower reverse salt flux than the CTA module. For both modules, fouling tests demonstrated that feed inlet pressure was more sensitive to foulant deposition than the flux, thus confirming that FO fouling deposition occurs in the feed channel rather than on the membrane surface. Osmotic backwash combined with physical cleaning used in this study confirmed to be effective and adapted to large-scale FO module operation.
Kim, JE, Phuntsho, S, Chekli, L, Hong, S, Ghaffour, N, Leiknes, T, Choi, JY & Shon, HK 2017, 'Environmental and economic impacts of fertilizer drawn forward osmosis and nanofiltration hybrid system', Desalination, vol. 416, pp. 76-85.
View/Download from: Publisher's site
View description>>
© 2017 Environmental and economic impacts of the fertilizer drawn forward osmosis (FDFO) and nanofiltration (NF) hybrid system were conducted and compared with conventional reverse osmosis (RO) hybrid scenarios using microfiltration (MF) or ultrafiltration (UF) as a pre-treatment process. The results showed that the FDFO-NF hybrid system using thin film composite forward osmosis (TFC) FO membrane has less environmental impact than conventional RO hybrid systems due to lower consumption of energy and cleaning chemicals. The energy requirement for the treatment of mine impaired water by the FDFO-NF hybrid system was 1.08 kWh/m3, which is 13.6% less energy than an MF-RO and 21% less than UF-RO under similar initial feed solution. In a closed-loop system, the FDFO-NF hybrid system using a TFC FO membrane with an optimum NF recovery rate of 84% had the lowest unit operating expenditure of AUD $0.41/m3. Besides, given the current relatively high price and low flux performance of the cellulose triacetate and TFC FO membranes, the FDFO-NF hybrid system still holds opportunities to reduce operating expenditure further. Optimizing NF recovery rates and improving the water flux of the membrane would decrease the unit OPEX costs, although the TFC FO membrane would be less sensitive to this effect.
Kim, Y, Li, S, Chekli, L, Phuntsho, S, Ghaffour, N, Leiknes, T & Shon, HK 2017, 'Influence of fertilizer draw solution properties on the process performance and microbial community structure in a side-stream anaerobic fertilizer-drawn forward osmosis – ultrafiltration bioreactor', Bioresource Technology, vol. 240, pp. 149-156.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd In this study, a side-stream anaerobic fertilizer-drawn forward osmosis (FDFO) and ultrafiltration (UF) membrane bioreactor (MBR) hybrid system was proposed and operated for 55 days. The FDFO performance was first investigated in terms of flux decline with various fertilizers draw solution. Flux decline was very severe with all fertilizers due to the absence of aeration and the sticky property of sludge. Flux recovery by physical cleaning varied significantly amongst tested fertilizers which seriously affected biofouling in FDFO via reverse salt flux (RSF). Besides, RSF had a significant impact on nutrient accumulation in the bioreactor. These results indicated that nutrient accumulation negatively influenced the anaerobic activity. To elucidate these phenomena, bacterial and archaeal community structures were analyzed by pyrosequencing. Results showed that bacterial community structure was affected by fertilizer properties with less impact on archaeal community structure, which resulted in a reduction in biogas production and an increase in nitrogen content.
Kim, Y, Li, S, Chekli, L, Woo, YC, Wei, C-H, Phuntsho, S, Ghaffour, N, Leiknes, T & Shon, HK 2017, 'Assessing the removal of organic micro-pollutants from anaerobic membrane bioreactor effluent by fertilizer-drawn forward osmosis', Journal of Membrane Science, vol. 533, pp. 84-95.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. In this study, the behavior of organic micro-pollutants (OMPs) transport including membrane fouling was assessed in fertilizer-drawn forward osmosis (FDFO) during treatment of the anaerobic membrane bioreactor (AnMBR) effluent. The flux decline was negligible when the FO membrane was oriented with active layer facing feed solution (AL-FS) while severe flux decline was observed with active layer facing draw solution (AL-DS) with di-ammonium phosphate (DAP) fertilizer as DS due to struvite scaling inside the membrane support layer. DAP DS however exhibited the lowest OMPs forward flux or higher OMPs rejection rate compared to other two fertilizers (i.e., mono-ammonium phosphate (MAP) and KCl). MAP and KCl fertilizer DS had higher water fluxes that induced higher external concentration polarization (ECP) and enhanced OMPs flux through the FO membrane. Under the AL-DS mode of membrane orientation, OMPs transport was further increased with MAP and KCl as DS due to enhanced concentrative internal concentration polarization while with DAP the internal scaling enhanced mass transfer resistance thereby lowering OMPs flux. Physical or hydraulic cleaning could successfully recover water flux for FO membranes operated under the AL-FS mode but only partial flux recovery was observed for membranes operated under AL-DS mode because of internal scaling and fouling in the support layer. Osmotic backwashing could however significantly improve the cleaning efficiency.
Kim, Y, Woo, YC, Phuntsho, S, Nghiem, LD, Shon, HK & Hong, S 2017, 'Evaluation of fertilizer-drawn forward osmosis for coal seam gas reverse osmosis brine treatment and sustainable agricultural reuse', Journal of Membrane Science, vol. 537, pp. 22-31.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The fertilizer-drawn forward osmosis (FDFO) was investigated for treating coal seam gas (CSG) produced water to generate nutrient rich solution for irrigation. Its performance was evaluated and compared with reverse osmosis (RO) in terms of specific energy consumption (SEC) and nutrient concentrations in the final product water. The RO-FDFO hybrid process was developed to further improve FDFO. The results showed that FDFO has the lowest SEC followed by the RO-FDFO and RO processes. The final nutrient concentration simulation demonstrated that the RO-FDFO hybrid process has lower final concentration, higher maximum recovery and lower nutrient loss than the stand alone FDFO process. Therefore, it was suggested that the RO-FDFO is the most effective treatment option for CSG produced water as well as favourable nutrient supply. Lastly, membrane fouling mechanism was examined in CSG RO brine treatment by FDFO, and the strategies for controlling fouling were critically evaluated. KNO3 exhibited the highest flux decline corresponding to the highest reverse salt flux, while the most severe membrane scaling was observed with calcium nitrate, primarily due to the reverse transport of calcium ions. To control membrane fouling in FDFO process, both physical flushing and chemical cleaning were examined. Membrane cleaning with citric acid of 5% resulted in a complete flux recovery.
Kook, S, Kim, J, Kim, S-J, Lee, J, Han, D, Phuntsho, S, Shim, W-G, Hwang, M, Shon, HK & Kim, IS 2017, 'Effect of initial feed and draw flowrates on performance of an 8040 spiral-wound forward osmosis membrane element', DESALINATION AND WATER TREATMENT, vol. 72, pp. 1-12.
View/Download from: Publisher's site
View description>>
© 2017, Desalination Publications. All rights reserved. This study investigated the effects of initial feed (20–50 L/min) and draw flowrates (2–5 L/min) on 8040 spiral-wound FO element performances in serial configuration for a forward osmosis and reverse osmosis (FO-RO) hybrid system employing single element-based tests. Average Jw,ave values for varying feed and draw flowrates were found to be 20.93, 19.38 and 18.71 LMH at E1, E2 and E3 (first, second and third elements in a serial configuration), respectively, with averaged diluted draw concentrations of 12.55, 7.88 and 5.77 g/L (initial conc. = 35 g/L). The draw stream dilution was not governed by Jw,ave but by the initial draw flowrates at the inlet that governs the retention time of the draw water body in the element. To sum up the performance results, it was concluded that initial draw flowrate is found to govern the performances of FO elements in series in terms of both production of diluted draw stream, determined by the averaged water flux of the FO element, Jw,ave, and the degree of draw stream dilution. Specific energy consumptions (SECs) of RO were estimated with varying RO feed concentrations (i.e. diluted draw concentration); it was observed the efficiency of SEC reduction by the dilution significantly decays after a critical RO recovery rate. This study successfully provides a valuable insight for feasible application of the FO-RO hybrid system.
Kumara, C & Indraratna, B 2017, 'Normal Deformation and Formation of Contacts in Rough Rock Fractures and Their Influence on Fluid Flow', International Journal of Geomechanics, vol. 17, no. 1, pp. 04016022-04016022.
View/Download from: Publisher's site
Kusumo, F, Silitonga, AS, Masjuki, HH, Ong, HC, Siswantoro, J & Mahlia, TMI 2017, 'Optimization of transesterification process for Ceiba pentandra oil: A comparative study between kernel-based extreme learning machine and artificial neural networks', Energy, vol. 134, pp. 24-34.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd In this study, kernel-based extreme learning machine (K-ELM) and artificial neural network (ANN) models were developed in order to predict the conditions of an alkaline-catalysed transesterification process. The reliability of these models was assessed and compared based on the coefficient of determination (R2), root mean squared error (RSME), mean average percent error (MAPE) and relative percent deviation (RPD). The K-ELM model had higher R2 (0.991) and lower RSME, MAPE and RPD (0.688, 0.388 and 0.380) compared to the ANN model (0.984, 0.913, 0.640 and 0.634). Based on these results, the K-ELM model is a more reliable prediction model and it was integrated with ant colony optimization (ACO) in order to achieve the highest Ceiba pentandra methyl ester yield. The optimum molar ratio of methanol to oil, KOH catalyst weight, reaction temperature, reaction time and agitation speed predicted by the K-ELM model integrated with ACO was 10:1, 1 %wt, 60 °C, 108 min and 1100 rpm, respectively. The Ceiba pentandra methyl ester yield attained under these optimum conditions was 99.80%. This novel integrated model provides insight on the effect of parameters investigated on the methyl ester yield, which may be useful for industries involved in biodiesel production.
Kusumo, F, Silitonga, AS, Ong, HC, Masjuki, HH & Mahlia, TMI 2017, 'A comparative study of ultrasound and infrared transesterification of Sterculia foetida oil for biodiesel production', Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 39, no. 13, pp. 1339-1346.
View/Download from: Publisher's site
View description>>
© 2017 Taylor & Francis. In this study, biodiesel production using ultrasound and infrared techniques is introduced. The ultrasound and infrared techniques are more efficient for biodiesel production since they improve the mass transfer between the immiscible reactants, increase chemical reactions, and decrease the reaction time and energy consumption. The effect of the reaction time on the acid value of the esterified Sterculia feotida oil is also investigated and it is found that the acid value is 0.76 and 0.85 mg KOH/g for the ultrasound and infrared technique, respectively, at a reaction time of 60 min. In addition, it is found that the biodiesel yield obtained from the ultrasound technique is higher (99.41%) compared to the infrared technique (98.55%) at a reaction time of 60 min. The KOH catalyst is analyzed for both of these techniques and it is found that the ultrasound technique gives faster absorbed reaction compared to the infrared technique. Hence, it can be concluded that the ultrasound and infrared transesterification techniques are promising techniques for biodiesel production.
Lam, MK, Yusoff, MI, Uemura, Y, Lim, JW, Khoo, CG, Lee, KT & Ong, HC 2017, 'Cultivation of Chlorella vulgaris using nutrients source from domestic wastewater for biodiesel production: Growth condition and kinetic studies', Renewable Energy, vol. 103, pp. 197-207.
View/Download from: Publisher's site
Lang, L, Pocquet, M, Ni, B-J, Yuan, Z & Spérandio, M 2017, 'Comparison of different two-pathway models for describing the combined effect of DO and nitrite on the nitrous oxide production by ammonia-oxidizing bacteria', Water Science and Technology, vol. 75, no. 3, pp. 491-500.
View/Download from: Publisher's site
View description>>
The aim of this work is to compare the capability of two recently proposed two-pathway models for predicting nitrous oxide (N2O) production by ammonia-oxidizing bacteria (AOB) for varying ranges of dissolved oxygen (DO) and nitrite. The first model includes the electron carriers whereas the second model is based on direct coupling of electron donors and acceptors. Simulations are confronted to extensive sets of experiments (43 batches) from different studies with three different microbial systems. Despite their different mathematical structures, both models could well and similarly describe the combined effect of DO and nitrite on N2O production rate and emission factor. The model-predicted contributions for nitrifier denitrification pathway and hydroxylamine pathway also matched well with the available isotopic measurements. Based on sensitivity analysis, calibration procedures are described and discussed for facilitating the future use of those models.
Le, TM, Fatahi, B, Khabbaz, H & Sun, W 2017, 'Numerical optimization applying trust-region reflective least squares algorithm with constraints to optimize the non-linear creep parameters of soft soil', Applied Mathematical Modelling, vol. 41, pp. 236-256.
View/Download from: Publisher's site
View description>>
© 2016 Determination of the creep model parameters is a challenging task particularly when a non-linear elastic visco-plastic (EVP) model is adopted, mainly due to the limited test duration as well as the assumption of the reference time. Therefore, this paper presents an innovative numerical solution to find the EVP model parameters applying the trust-region reflective least square optimization algorithm. The developed approach involves several available laboratory consolidation test results in the optimization procedure with the adopted commencing time to creep as a unit of time. In this paper, the laboratory results of Ottawa clay were employed to demonstrate the limitation of the recent method to obtain model parameters. Furthermore, the developed method is verified against Skå-Edeby clay in the laboratory conditions. The EVP model parameters are obtained by applying the developed method to the available laboratory consolidation results of clay samples. The analysis results of vertical strains and excess pore water pressures demonstrate that the developed method can be a feasible tool to estimate the settlement properties of clays.
Lee, E-J, An, AK, Hadi, P, Lee, S, Woo, YC & Shon, HK 2017, 'Advanced multi-nozzle electrospun functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PVDF-HFP) composite membranes for direct contact membrane distillation', Journal of Membrane Science, vol. 524, pp. 712-720.
View/Download from: Publisher's site
View description>>
The unique capabilities of electrospinning technology are being increasingly utilized in the fabrication of hydrophobic membranes to improve the membrane distillation (MD) process in recent years. In this study, hydrophobic titanium dioxide (TiO2) nanoparticles functionalized by fluorosilane were incorporated into electrospun membranes using single, coaxial, and dual nozzles to develop novel membrane architectures for improved physico-chemical properties for MD. By incorporating fluorosilane coated TiO2 into the PVDF-HFP solution during the membrane synthesis and using an advanced multi-nozzle to form various hierarchical membrane structures tuned the size and structure of the nanofibers and made them vastly superior for the application in MD. The single and coaxial nozzle membranes showed contact angles close to 150° and the dual-nozzle membrane assembled bead-on-string fibers achieved superhydrophobicity (i.e., contact angle of 153.4°). To test the functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PVDF-HFP) composite membranes for MD performance, the membranes were subjected to long-term direct contact MD for about two days to monitor their water vapor flux and selectivity. Compared to commercial PVDF membranes, all electrospun F-TiO2/ PVDF-HFP membrane achieved higher water vapor flux of 40 L m−2 h−1 (60 °C feed and 20 °C permeate) with a brine (7.0 wt% NaCl) as the feed solution and also exhibited anti-wetting property while maintaining high water flux compared to the membrane without TiO2 incorporation.
Lee, E-J, Deka, BJ, Guo, J, Woo, YC, Shon, HK & An, AK 2017, 'Engineering the Re-Entrant Hierarchy and Surface Energy of PDMS-PVDF Membrane for Membrane Distillation Using a Facile and Benign Microsphere Coating', Environmental Science & Technology, vol. 51, no. 17, pp. 10117-10126.
View/Download from: Publisher's site
View description>>
© 2017 American Chemical Society. To consolidate the position of membrane distillation (MD) as an emerging membrane technology that meets global water challenges, it is crucial to develop membranes with ideal material properties. This study reports a facile approach for a polyvinylidene fluoride (PVDF) membrane surface modification that is achieved through the coating of the surface with poly(dimethylsiloxane) (PDMS) polymeric microspheres to lower the membrane surface energy. The hierarchical surface of the microspheres was built without any assistance of a nano/microcomposite by combining the rapid evaporation of tetrahydrofuran (THF) and the phase separation from condensed water vapor. The fabricated membrane exhibited superhydrophobicity - a high contact angle of 156.9° and a low contact-angle hysteresis of 11.3° - and a high wetting resistance to seawater containing sodium dodecyl sulfate (SDS). Compared with the control PVDF-hexafluoropropylene (HFP) single-layer nanofiber membrane, the proposed fabricated membrane with the polymeric microsphere layer showed a smaller pore size and higher liquid entry pressure (LEP). When it was tested for the direct-contact MD (DCMD) in terms of the desalination of seawater (3.5% of NaCl) containing SDS of a progressively increased concentration, the fabricated membrane showed stable desalination and partial wetting for the 0.1 and 0.2 mM SDS, respectively.
Lee, S, Shon, HK & Hong, S 2017, 'Dewatering of activated sludge by forward osmosis (FO) with ultrasound for fouling control', Desalination, vol. 421, pp. 79-88.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Ultrasound was used to improve a forward osmosis (FO) sludge dewatering process for the control of fouling by deposited sludge flocs. FO was able to concentrate activated sludge from a real-scale wastewater reclamation plant. However, the flux decline indicated a severe fouling phenomenon. To mitigate this FO fouling, ultrasound radiation using a novel cell configuration was applied. However, the application of continuous radiation unexpectedly resulted in more severe fouling. Fluorescence excitation-emission matrix (FEEM) spectroscopy showed that longer ultrasound radiation applications caused high organic release from sludge flocs. Confocal scanning laser microscopy (CLSM) clearly identified a thicker organic fouling layer on the FO membrane surface. Ultrasound cleaning was optimized for radiation length and improved by the integration of flushing. Specifically, the combination of ultrasound and flushing caused a flux loss recovery of 70% or more. This work demonstrated the possibility of ultrasound cleaning as a fouling control method for FO sludge dewatering applications.
Leong, KY, Ku Ahmad, KZ, Ong, HC, Ghazali, MJ & Baharum, A 2017, 'Synthesis and thermal conductivity characteristic of hybrid nanofluids – A review', Renewable and Sustainable Energy Reviews, vol. 75, pp. 868-878.
View/Download from: Publisher's site
Leong, KY, Najwa, ZA, Ku Ahmad, KZ & Ong, HC 2017, 'Investigation on Stability and Optical Properties of Titanium Dioxide and Aluminum Oxide Water-Based Nanofluids', International Journal of Thermophysics, vol. 38, no. 5.
View/Download from: Publisher's site
Li, H, Zhou, B, Tian, Z, Guo, J, Ngo, HH, Lu, C, Han, Y & Song, Y 2017, 'Improving anoxic/aerobic nutrients removal by the enhanced biological phosphorus removal-sulfur autotrophic denitrification (EBPR-SAD) system when treating low C/N ratio municipal wastewater', DESALINATION AND WATER TREATMENT, vol. 95, pp. 247-261.
View/Download from: Publisher's site
View description>>
© 2017 Desalination Publications. All rights reserved. A novel nutrients removal system integrating enhanced biological phosphorus removal (EBPR) and sulfur autotrophic denitrification (SAD) was developed to upgrade the Shenyang Degremont Anoxic Oxic process (SDAO). In this system, the EBPR process was mainly employed to utilize organic carbon for denitrification and phosphorus removal; the SAD process was used to remove nitrate, which was not removed in the EBPR process because of a low C/N ratio. The results showed that the EBPR-SAD effluent COD, TN, NH4+–N and TP were 24.6, 1.21, 1.09 and 0.24 mg/L, respectively. Compared with those of the original system, the removal efficiencies of TN and TP increased to 95.8% and 86.9%. It was demonstrated that the EBPR-SAD system could achieve nearly complete nutrients removal from low C/N ratio municipal wastewater. Cluster analysis and principal coordinate analysis showed that bacterial community structures were significantly different between SDAO, EBPR and SAD processes, indicating that bacterial community structures were affected by the type of wastewater biotreatment system. Taxonomic analysis showed that the nine most abundant phyla in the SDAO and EBPR-SAD system accounted for 87.0%–90.7% of the total effective sequences. Redundancy analysis was used to reveal the relationship between the abundance of bacterial phyla and environmental parameters in the SDAO and EBPR-SAD system.
Li, J, Hao, H & Wu, C 2017, 'Numerical study of precast segmental column under blast loads', Engineering Structures, vol. 134, pp. 125-137.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd Constructions with precast technology have seen a fast development over the past several decades. Despite advantages including short construction period, better quality control, less environmental and traffic impact, a lack of study on their behaviour under dynamic loads have prevented the widespread use of precast constructions in high seismic zones and where terrorist attack could be a concern. Among all precast structural components, precast segmental columns have been found one of the construction techniques with great potentials. Intensive research efforts have been spent on investigating the segmental columns under seismic loadings in recent years. During its service life, besides seismic action, structure may subject to other dynamic loads like impact and blast. It is therefore important to perform multi-hazard analyse to better understand structural performance. This study investigates the blast loading resistance capacities of segmental reinforced concrete (RC) columns. RC segmental columns with or without shear keys and energy dissipation bars are considered. Influence of the number of segments and different levels of post tensioning forces on column dynamic performance is also investigated. Commercial code LS-DYNA is used to perform numerical simulations of the segmental columns under different blast loadings. Accuracy of the numerical model is verified against available testing data on RC columns. Numerical results of the segmental columns under different blast loadings are calculated and compared with those of the monolithic RC columns. Discussions on the capabilities of segmental RC columns in resisting blasting loads are made with respect to those of the monolithic RC columns.
Li, J, Jiang, B, Liu, Y, Qiu, C, Hu, J, Qian, G, Guo, W & Ngo, HH 2017, 'Preparation and adsorption properties of magnetic chitosan composite adsorbent for Cu 2+ removal', Journal of Cleaner Production, vol. 158, pp. 51-58.
View/Download from: Publisher's site
Li, J, Masia, MJ & Stewart, MG 2017, 'Stochastic spatial modelling of material properties and structural strength of unreinforced masonry in two-way bending', Structure and Infrastructure Engineering, vol. 13, no. 6, pp. 683-695.
View/Download from: Publisher's site
View description>>
The paper describes the development of a computational method to predict the strength for unreinforced masonry walls subject to two-way out-of-plane bending considering unit-to-unit spatial variability of the material properties of mortar joints and bricks. The study involves conducting a numerical simulation of full-sized walls subject to two-way bending using stochastic analysis in the form of Monte Carlo simulations and comparing the results with experimental work. A 3-D non-linear Finite Element Analysis is used to study how the spatial variability of material properties affect non-load bearing wall failure progression. The numerical results are compared to the experimental results in terms of the wall failure progression and wall capacity. It is shown that the model which considers the spatial variability of brickwork can best capture the failure patterns and predict the cracking and ultimate loads for walls subjected to two-way bending.
Li, J, Wu, C, Hao, H & Liu, Z 2017, 'Post-blast capacity of ultra-high performance concrete columns', Engineering Structures, vol. 134, pp. 289-302.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd Over the past several decades, iconic and public buildings have become targets of terrorist bomb attacks, but most of these buildings were built without consideration of blast loading scenarios. Key load-carrying elements such as concrete columns are probably the most critical structural components for structural protection against bomb threats. Failures of columns may trigger catastrophic progressive collapse if there is insufficient structural redundancy. In a recent study, novel ultra-high performance concrete (UHPC) material formulated based on reactive powder concrete (RPC) was developed. Field blast tests on columns made of this material were performed. Test results showed that UHPC columns had excellent blast resistant capability, only small mid-height deflection and minor concrete damage was observed after the blasting tests. In the present study, to quantify blast-induced damage and assess residual loading capacity of UHPC columns, static axial loading tests on post-blast UHPC columns were carried out. Undamaged control samples were tested to provide benchmarks. Damage index and residual loading capacity of UHPC columns after various blast loadings were obtained. It was found that column cast with micro steel fibre reinforced UHPC preserved more than 70% of its loading capacity after 35 kg TNT detonation at 1.5 m standoff distance, while high strength concrete column only maintained 40% loading capacity after 8 kg TNT detonation at 1.5 m standoff distance.
Li, J, Wu, C, Hao, H & Su, Y 2017, 'Experimental and numerical study on steel wire mesh reinforced concrete slab under contact explosion', Materials & Design, vol. 116, pp. 77-91.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd With the rising of terrorism and rapid urbanization around the world, increasingly more structures are exposed to the threats from accidental and hostile explosion loads. To provide adequate structural protection against blast load, novel materials and strengthening techniques are under fast development. In the present study, a composite slab design aiming at high level blast resistance is studied. In the matrix of high strength self-compacting concrete, besides conventional rebars serving as primary reinforcement, steel wire meshes are embedded and served as secondary reinforcements. Moreover, on the concrete cover layer where the tensile cracks locate, steel fibres are added to provide micro crack-bridging effect. Preliminary numerical simulations adopting coupled Finite Element (FE) and Smoothed Particle Hydrodynamics (SPH) are carried out in hydro-code and the results are used as guide for field blast test. Composite slab with optimal design is field tested under 1 kg TNT contact detonation, and the results are compared with slabs made of conventional and ultra-high performance concrete without steel wire meshes. The results demonstrate that slab with steel wire mesh reinforcement develops localized membrane effect when subjected to blast loads and shows better blast resistant capability as compared to the slabs without steel wire meshes.
Li, J, Wu, C, Hao, H, Su, Y & Li, Z-X 2017, 'A study of concrete slabs with steel wire mesh reinforcement under close-in explosive loads', International Journal of Impact Engineering, vol. 110, pp. 242-254.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Structural responses and damages under blast loading environments are critical to structural and personnel safety. The blast scenarios involving close-in detonations are attracting increasingly more attentions over the last few decades due to the rising of terrorism. Under close-in detonations, structural elements tend to fail in a brittle mode including shear, concrete crater and spall. In such loading scenarios, the structural designated loading capacity which is usually based on flexural deformation assumption is not fully developed. To provide high-level structural protection, high performance concretes with varying fibre additions are now widely investigated and used in blast resistance designs. In the present study, field blast tests results on reinforced concrete slabs under close-in detonations are presented. Performances of slabs made of normal strength concrete and steel fibre reinforced concrete are compared and discussed. Besides conventional steel rebar reinforcement, new reinforcement scheme i.e. hybrid steel wire mesh-micro steel fibre reinforcement is investigated through the laboratory static tests and field blast tests. Furthermore, a numerical study based on Multi-Material ALE and Lagrangian algorithm is carried out to further investigate the field tests’ phenomenon.
Li, M, Wu, H, Zhang, J, Ngo, HH, Guo, W & Kong, Q 2017, 'Nitrogen removal and nitrous oxide emission in surface flow constructed wetlands for treating sewage treatment plant effluent: Effect of C/N ratios', Bioresource Technology, vol. 240, pp. 157-164.
View/Download from: Publisher's site
View description>>
In order to design treatment wetlands with maximal nitrogen removal and minimal nitrous oxide (N2O) emission, the effect of influent C/N ratios on nitrogen removal and N2O emission in surface flow constructed wetlands (SF CWs) for sewage treatment plant effluent treatment was investigated in this study. The results showed that nitrogen removal and N2O emission in CWs were significantly affected by C/N ratio of influent. Much higher removal efficiency of NH4(+)-N (98%) and TN (90%) was obtained simultaneously in SF CWs at C/N ratios of 12:1, and low N2O emission (8.2mg/m(2)/d) and the percentage of N2O-N emission in TN removal (1.44%) were also observed. These results obtained in this study would be utilized to determine how N2O fluxes respond to variations in C/N ratios and to improve the sustainability of CWs for wastewater treatment.
Li, S, Kim, Y, Chekli, L, Phuntsho, S, Shon, HK, Leiknes, T & Ghaffour, N 2017, 'Impact of reverse nutrient diffusion on membrane biofouling in fertilizer-drawn forward osmosis', Journal of Membrane Science, vol. 539, pp. 108-115.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Biofouling in fertilizer-drawn forward osmosis (FDFO) for water reuse was investigated by spiking pure bacteria species Pseudomonas aeruginosa PAO1+GFP and using three different fertilizers KNO3, KCl and KH2PO4 as draw solutions. The performance of FO process for treating synthetic wastewater was assessed and their influence on the membrane fouling and in particular biofouling was evaluated relative to the type of different fertilizers used and their rates of reverse diffusion. FO performances using KNO3 as draw solute exhibited severer flux decline (63%) than when using KCl (45%) and KH2PO4 (30%). Membrane autopsy indicated that the mass of organic foulants and biomass on fouled membrane surface using KNO3 as draw solute (947.5 mg/m2 biopolymers, 72 µm biofilm thickness and 53.3 mg/m2 adenosine triphosphate) were significantly higher than that using KCl (450 mg/m2 biopolymers, 33 µm biofilm thickness and 28.2 mg/m2 ATP) and KH2PO4 (440 mg/m2 biopolymers, 35 µm biofilm thickness and 33.5 mg/m2 ATP). This higher flux decline is likely related to the higher reverse diffusion of KNO3 (19.8 g/m2/h) than KCl (5.1 g/m2/h) and KH2PO4 (3.7 g/m2/h). The reverse diffused potassium could promote the organics and bacterial adhesion on FO membrane via charge screening effect and compression of electrical double layer. Moreover, reverse diffused nitrate provided increased N:P nutrient ratio was favorable for the bacteria to grow on the feed side of the FO membrane.
Li, S, Kim, Y, Phuntsho, S, Chekli, L, Shon, HK, Leiknes, T & Ghaffour, N 2017, 'Methane production in an anaerobic osmotic membrane bioreactor using forward osmosis: Effect of reverse salt flux', Bioresource Technology, vol. 239, pp. 285-293.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This study investigated the impact of reverse salt flux (RSF) on microbe community and bio-methane production in a simulated fertilizer driven FO-AnMBR system using KCl, KNO3 and KH2PO4 as draw solutes. Results showed that KH2PO4 exhibited the lowest RSF in terms of molar concentration 19.1 mM/(m2.h), while for KCl and KNO3 it was 32.2 and 120.8 mM/(m2.h), respectively. Interestingly, bio-methane production displayed an opposite order with KH2PO4, followed by KCl and KNO3. Pyrosequencing results revealed the presence of different bacterial communities among the tested fertilizers. Bacterial community of sludge exposed to KH2PO4 was very similar to that of DI-water and KCl. However, results with KNO3 were different since the denitrifying bacteria were found to have a higher percentage than the sludge with other fertilizers. This study demonstrated that RSF has a negative effect on bio-methane production, probably by influencing the sludge bacterial community via environment modification.
Li, W, Huang, Z, Hu, G, Hui Duan, W & Shah, SP 2017, 'Early-age shrinkage development of ultra-high-performance concrete under heat curing treatment', Construction and Building Materials, vol. 131, pp. 767-774.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd The effects of a novel heat curing regime and longitudinal reinforcement ratio on early-age shrinkage of ultra-high performance concrete (UHPC) were experimentally investigated in this study. The microstructure, porosity and calcium hydroxide (CH) content of UHPC after different heat curing durations were characterized with scanning electron microscopy, mercury intrusion porosimetry and thermal analysis. The results indicate that slight shrinkage was observed when the heat curing duration was less than 60 min and curing temperature reached 48 °C. However, when the heat curing duration approached 70 min and curing temperature was around 55 °C, the early-age shrinkage increased dramatically. It was found that the early-age shrinkage is approximately 450 με after 48 h of heat curing. The results also show that the early-age shrinkage of UHPC significantly decreased by percentage of 33–60% with the increase of longitudinal steel reinforcement ratio from 2.0 to 4.52%. Meantime, after 10 h of heat curing, the cement hydration and secondary hydration in UHPC tend to finish, which consequently leads to dense microstructure and low CH content in UHPC.
Li, W, Li, X, Chen, SJ, Liu, YM, Duan, WH & Shah, SP 2017, 'Effects of graphene oxide on early-age hydration and electrical resistivity of Portland cement paste', Construction and Building Materials, vol. 136, pp. 506-514.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The effects of graphene oxide (GO) on the early-age hydration process and mechanical properties of Portland cement paste were experimentally investigated in this study. Based on an isothermal calorimeter measurement, the hydration rate of cement was observed to increase with the increase of GO content by nucleation effect. On the other hand, the electrical resistivity development of GO-cement paste was monitored using a non-contact electrical resistivity device. The result showed that electrical the resistivity of GO-cement paste was evidently higher than that of plain cement paste. However, cement paste with excessive amounts of GO exhibited a decreased electrical resistivity due to the massive ion diffusion caused by GO. Compared to plain cement paste, the GO-cement paste exhibited obviously higher compressive and flexural strengths, but the enhancements in compressive strength began to decline when the GO amount was greater than 0.04%. The microstructure characterization indicated that GO can apparently densify the cement pastes with less porosity and hydrates networking, which is consistent with the results of hydration acceleration and strength enhancement.
Li, W, Li, X, Chen, SJ, Long, G, Liu, YM & Duan, WH 2017, 'Effects of Nanoalumina and Graphene Oxide on Early-Age Hydration and Mechanical Properties of Cement Paste', Journal of Materials in Civil Engineering, vol. 29, no. 9, pp. 04017087-04017087.
View/Download from: Publisher's site
View description>>
© 2017 American Society of Civil Engineers. The effects of nanoalumina (NA) and graphene oxide (GO) on the early-age hydration and mechanical properties of portland cement pastes were investigated in this study. The hydration heat release rate and cumulative heat of cement pastes incorporating different dosages of NA and GO were evaluated using an isothermal calorimeter measurement method. Early-age electrical resistivity development was investigated by a noncontact electrical resistivity technique. The results show that both NA and GO could efficiently accelerate cement hydration. As a physical filler, NA significantly accelerates the hydration of tricalcium aluminate (C3A) in cement. On the other hand, GO is able to obviously reduce the dormant period of cement hydration and shift the heat flow peaks to the left by accelerating the hydration of tricalcium silicate (C3S) in cement. Compared to plain cement pastes, both the compressive and flexural strengths of cement pastes incorporating NA or GO are significantly increased. However, when NA and GO contents exceed the optimal amounts, improvements in flexural strength tend to decline, which is probably due to particle agglomeration. NA-cement paste exhibited slightly higher electrical resistivity than plain cement paste during hydration acceleration and deceleration stages. But GO-cement paste clearly showed lower electrical resistivity, which might be attributed to iron diffusion caused by GO with large surface areas.
Li, W, Long, C, Tam, VWY, Poon, C-S & Hui Duan, W 2017, 'Effects of nano-particles on failure process and microstructural properties of recycled aggregate concrete', Construction and Building Materials, vol. 142, pp. 42-50.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The effects of nano-particles including nano-silica (NS) and nano-limestone (NL) on the crack propagation and microstructure properties of recycled aggregate concrete (RAC) were experimentally investigated in this study. The crack initiation and propagation of nano-particles modified RAC with different nano-particle modification were evaluated using digital image correlation technique (DIC). The microstructures and porosity of interfacial transition zones (ITZ) in nano-modified RAC were also examined using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). It was found that the micro-cracks were typically derived from relatively weak ITZs in RAC, and then progressively propagated along the compressive loading direction. The meso-crack developments eventually led to final splitting failure. The results indicated that compared to NL, NS was more effective in improving the microstructure properties and enhance the mechanical strength of RAC. The porosity and water absorption of RAC were obviously reduced by the NS incorporation. However, due to particles agglomeration, NL could not effectively improve the microstructure of RAC for further enhancing the RAC mechanical properties. Furthermore, in terms of severe particles agglomeration, NL was even detrimental to the mechanical strength of RAC especially at the late-age.
Li, W, Luo, Z, Tao, Z, Duan, WH & Shah, SP 2017, 'Mechanical behavior of recycled aggregate concrete-filled steel tube stub columns after exposure to elevated temperatures', Construction and Building Materials, vol. 146, pp. 571-581.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The compressive mechanical behaviors of recycled aggregate concrete-filled steel tube (RACFST) stub columns after exposure to elevated temperatures were experimentally investigated in this study. The RACFST stub columns incorporating different recycled coarse aggregate (RCA) replacement ratios of 0, 50% and 100% were heated under elevated temperatures of 200 °C, 500 °C, and 700 °C. The results show that the compressive strength and elastic modulus of RACFST columns were relatively inferior to those of the corresponding natural aggregate concrete-filled steel tube (NACFST) columns after exposure to the same elevated temperatures, and the degradations became more pronounced with increasing RCA replacement ratio and higher temperature. This phenomenon might be attributed to the lower resistance of recycled aggregate concrete (RAC) than natural aggregate concrete (NAC) when was exposed to elevated temperatures. However, after elevated temperature exposure, the peak strain of RACFST stub column was relatively higher than that of the NACFST counterpart. Degradation regression formulas of mechanical properties and deformation behaviors of RACFST stub columns after exposure to elevated temperatures were proposed and agreed well with the experimental results.
Li, W, Sun, Z, Luo, Z & Shah, SP 2017, 'Retraction: Influence of Relative Mechanical Strengths between New and Old Cement Mortars on the Crack Propagation of Recycled Aggregate Concrete', Journal of Advanced Concrete Technology, vol. 15, no. 3, pp. 110-125.
View/Download from: Publisher's site
Li, X, Liu, YM, Li, WG, Li, CY, Sanjayan, JG, Duan, WH & Li, Z 2017, 'Effects of graphene oxide agglomerates on workability, hydration, microstructure and compressive strength of cement paste', Construction and Building Materials, vol. 145, pp. 402-410.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd In this study, the effects of graphene oxide (GO) agglomerates on the workability, hydration, microstructure, and compressive strength of cement paste were addressed. The workability of cement paste was reduced because of the presence of GO agglomerates, which entrap a large amount of water. The mini-slump diameter was reduced by 21% with the incorporation of 0.03% by weight GO in cement paste. Hydration of the cement paste was accelerated due to nucleation sites provided by GO agglomerates serving as seeding material in the cement paste. The incorporation of GO refined the pore structure of the cement paste. The incorporation of GO was found to have much greater impact on macropores than on large and small mesopores. At 28 days, the incorporation of 0.04% by weight GO produced a 14% improvement in the compressive strength of cement paste. Below 0.03%, the incorporation of GO had no positive effects on compressive strength.
Li, X, Lu, Z, Chuah, S, Li, W, Liu, Y, Duan, WH & Li, Z 2017, 'Effects of graphene oxide aggregates on hydration degree, sorptivity, and tensile splitting strength of cement paste', Composites Part A: Applied Science and Manufacturing, vol. 100, pp. 1-8.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd It has recently been found the graphene oxide (GO) aggregates form in cement paste due to the chemical cross-linking of calcium cations. Therefore, the effects of GO addition on the properties of cement based materials should be dependent on the properties of GO aggregates rather than GO nanosheets. In this study, GO aggregates were first characterized by particle size measurement. Then, the effects of GO aggregates on the degree of hydration, sorptivity, and tensile strength of cement paste were investigated. The aspect ratio of GO aggregates is much larger than that of the original GO nanosheets. Compared to plain cement paste, the increase of non-evaporable water content of the cement paste was found to be very limited, around 1.17% and 3.90% for cement pastes containing 0.02% and 0.04% by weight GO, respectively. The sorptivity of cement paste, especially the secondary sorptivity, was notably reduced for GO incorporated cement paste. The tensile strength was significantly improved by GO aggregates. Incorporation of 0.04% by weight GO increased the tensile strength by 67% compared to that of plain cement paste.
Li, X, Mo, Y, Li, J, Guo, W & Ngo, HH 2017, 'In-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber membrane processes: A critical review', Journal of Membrane Science, vol. 528, pp. 187-200.
View/Download from: Publisher's site
Li, X, Tao, M, Wu, C, Du, K & Wu, Q 2017, 'Spalling strength of rock under different static pre-confining pressures', International Journal of Impact Engineering, vol. 99, pp. 69-74.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd A testing method of spalling strength at different static pre-confining pressure is proposed in this paper. Using a modified split Hopkinson bar facility, a static pre-confining pressure was loaded before dynamic loading. The pull-back method is used to calculate the spalling strength and the free surface velocities of the specimen were measured by a laser detector system. The experimental results indicate that the spalling strength is related to the static pre-confining pressures. When the impact loading and rate effect are almost the same, the results demonstrated that the spalling strength decreases with an increase in the confining pressure.
Liang, D, He, X & Zhang, J-X 2017, 'An ISPH model for flow-like landslides and interaction with structures', Journal of Hydrodynamics, vol. 29, no. 5, pp. 894-897.
View/Download from: Publisher's site
Lim, S, Park, MJ, Phuntsho, S, Tijing, LD, Nisola, GM, Shim, W-G, Chung, W-J & Shon, HK 2017, 'Dual-layered nanocomposite substrate membrane based on polysulfone/graphene oxide for mitigating internal concentration polarization in forward osmosis', Polymer, vol. 110, pp. 36-48.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd A novel thin-film composite (TFC) forward osmosis (FO) membrane with dual-layered substrate membrane was fabricated by a double-blade casting technique using different polysulfone (PSf) concentrations for top (15 wt%) and bottom (7 wt%) substrate layers. Graphene oxide (GO) was incorporated in the substrate layer, and the dual casting approach resulted in a membrane support with a highly porous bottom structure and a dense top skin layer on which the polyamide active layer was effectively formed. The dual-layered TFC PSf/GO membrane (TFC-PSfdGO) exhibited high water permeability, and ion selectivity was enhanced by the presence of well dispersed hydrophilic GO in the PSf substrate. The TFC-PSfdGO also exhibited the lowest specific reverse salt flux (Js/Jv = 0.19 g L-1) and a more favorable structural parameter (S = 130 μm) compared to GO-free membranes. Using deionized water as feed solution and 1 M NaCl as draw solution (DS), TFC-PSfdGO had Jv = 33.8 L m−2 h−1 and Js = 6.9 g−2 h−1 under AL-FS mode, and Jv = 61.5 L m−2h−1 and Js = 14.0 g−2 h−1 under AL-DS mode. The potential of TFC-PSfdGO for commercial application was further evaluated by fabricating it with a fabric backing support (denoted as TFC-PSfdGOf). Compared to TFC-PSfdGO, TFC-PSfdGOf exhibited only 14% decline in its water flux. The overall results reveal that, fabrication of TFC substrate membrane via dual-blade casting approach along with GO incorporation produced high-performance TFC FO membranes which likely reduced the internal concentration polarization effects.
Liu, H, Chen, J-G, Wang, C, Liu, Z-T, Li, Y, Liu, Z-W, Xiao, J & Lu, J 2017, 'Immobilization of Cyclometalated Iridium Complex onto Multiwalled Carbon Nanotubes for Dehydrogenation of Indolines in Aqueous Solution', Industrial & Engineering Chemistry Research, vol. 56, no. 40, pp. 11413-11421.
View/Download from: Publisher's site
Liu, J, Wu, C & Chen, X 2017, 'Numerical study of ultra-high performance concrete under non-deformable projectile penetration', Construction and Building Materials, vol. 135, pp. 447-458.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This paper presents a numerical study in evaluating impact response of ultra-high performance concrete (UHPC) cylinder targets under ogive-nosed projectile penetration with broad striking velocities from 300 m/s to 1000 m/s. Steel ogive-nosed projectiles with an average mass of 360 g are launched to penetrate UHPC cylinder targets with 750 mm diameter and 1000 mm length. The Karagozian & Case (K&C) cementitious material model, namely, MAT_Concrete_Damage_Rel3 (Mat_72R3), is implemented into finite element package LS-DYNA for UHPC. In order to accurately predict depth of penetration (DOP) and cratering damage of UHPC cylinder targets, uniaxial compressive and four-point bending testing results are used to validate 3D finite element material model. With the validated numerical model incorporating dynamic increase factors (DIF) of UHPC, parametric studies are conducted to investigate effects of UHPC compressive strength, projectile striking velocity and projectile caliber-radius-head (CRH) ratio on both DOP and cratering damage of UHPC targets. Moreover, an empirical formula to predict DOP is derived according to the simulated data.
Liu, J, Wu, C, Li, J, Su, Y, Shao, R, Liu, Z & Chen, G 2017, 'Experimental and numerical study of reactive powder concrete reinforced with steel wire mesh against projectile penetration', International Journal of Impact Engineering, vol. 109, pp. 131-149.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This paper presents experimental and numerical studies on impact resistance of reactive powder concrete (RPC) targets reinforced with 44-layer steel wire meshes. Steel ogive-nosed projectiles with an average mass of 330 g and striking velocities ranging from 550 m/s to 800 m/s were launched against the cylindrical RPC targets with 750 mm diameter and 700 mm thickness. The impact responses observed in the tests, including depth of penetration (DOP), crater diameter and volume loss, were investigated and discussed, which indicates an effective impact resistance of steel wire mesh reinforced RPC in comparison with the previous studies on ultra-high performance based cement composites (UHPCC) with additions of fibres and basalt aggregates. Numerical studies based on validated material and element models are also conducted to simulate the impact responses of reinforced RPC targets against high-velocity projectile penetration in explicit hydro-code LS-DYNA. The impact responses, especially for the DOP, are well predicted by using the numerical models. Moreover, further investigation based on the verified numerical models is discussed in the present paper to explore the influence of mechanical and physical properties of steel wire mesh reinforcement on the resistance of projectile penetration.
Liu, K, Law, SS & Zhu, XQ 2017, 'System parameter identification from projection of inverse analysis', Journal of Sound and Vibration, vol. 396, pp. 83-107.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The output of a system due to a change of its parameters is often approximated with the sensitivity matrix from the first order Taylor series. The system output can be measured in practice, but the perturbation in the system parameters is usually not available. Inverse sensitivity analysis can be adopted to estimate the unknown system parameter perturbation from the difference between the observation output data and corresponding analytical output data calculated from the original system model. The inverse sensitivity analysis is re-visited in this paper with improvements based on the Principal Component Analysis on the analytical data calculated from the known system model. The identification equation is projected into a subspace of principal components of the system output, and the sensitivity of the inverse analysis is improved with an iterative model updating procedure. The proposed method is numerical validated with a planar truss structure and dynamic experiments with a seven-storey planar steel frame. Results show that it is robust to measurement noise, and the location and extent of stiffness perturbation can be identified with better accuracy compared with the conventional response sensitivity-based method.
Liu, MD & Indraratna, B 2017, 'Strength Criterion for Intact Rock', Indian Geotechnical Journal, vol. 47, no. 3, pp. 261-264.
View/Download from: Publisher's site
View description>>
© 2016, Indian Geotechnical Society. Based on studies of the peak strength for soil by the authors, a simple strength criterion for intact rock is obtained in the general principal stress space. There are two material parameters in the equation. One is the uniaxial compression strength of the rock; the other describes the influence of stress level, and similar parameters are well studied in soil mechanics. It is seen that the proposed general strength criterion represents well the strength of various rocks and can provide a useful tool for geotechnical engineering practice.
Liu, T, Ma, B, Chen, X, Ni, B-J, Peng, Y & Guo, J 2017, 'Evaluation of mainstream nitrogen removal by simultaneous partial nitrification, anammox and denitrification (SNAD) process in a granule-based reactor', Chemical Engineering Journal, vol. 327, pp. 973-981.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The mainstream anaerobic ammonium oxidation (anammox) has attracted extensive attention recently, particularly due to its potential of transforming current wastewater treatment plants from energy consuming to energy neutral or positive. However, the presence of biodegradable chemical oxygen demanding (COD, 20–80 mg COD L−1) in the mainstream anammox reactor stimulates the growth of heterotrophic bacteria, which would compete for oxygen with ammonia-oxidizing bacteria (AOB) and for nitrite with anammox bacteria, thus interfering with the autotrophic nitrogen removal process. In the present work, with consideration of granule size distribution, a one-dimensional model describing the mainstream simultaneous partial nitrification, anammox and denitrification (SNAD) in a granule-based reactor was established, calibrated and validated, based on the long-term experimental results. Through applying the verified model, simulation studies were conducted and the results showed that the effluent total nitrogen concentration of <5 mg N L−1 could be achieved at C/N ratio of 0.2–0.6, DO concentration of 0.2–0.4 mg L−1 and granule radius of 300–600 μm. The combined effects indicated that the SNAD process with TN removal efficiency >90% was obtained at C/N ratio and DO concentration of 0.2–1.0 and 0.2–0.4 mg O2 L−1 respectively. Finally, the various granule size distribution patterns were simulated, which confirmed that the size distribution needed to be incorporated in the model to accurately describe the granular anammox system, considering a model based on a uniform granule size does not reflect the real situations. These results provide guides to optimize the operation of mainstream granular autotrophic nitrogen removal process.
Liu, Y, Ngo, HH, Guo, W, Sun, J, Wang, D, Peng, L & Ni, B-J 2017, 'Modeling aerobic biotransformation of vinyl chloride by vinyl chloride-assimilating bacteria, methanotrophs and ethenotrophs', Journal of Hazardous Materials, vol. 332, pp. 97-103.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Recent studies have investigated the potential of enhanced groundwater Vinyl Chloride (VC) remediation in the presence of methane and ethene through the interactions of VC-assimilating bacteria, methanotrophs and ethenotrophs. In this study, a mathematical model was developed to describe aerobic biotransformation of VC in the presence of methane and ethene for the first time. It examines the metabolism of VC by VC-assimilating bacteria as well as cometabolism of VC by both methanotrophs and ethenotrophs, using methane and ethene respectively, under aerobic conditions. The developed model was successfully calibrated and validated using experimental data from microcosms with different experimental conditions. The model satisfactorily describes VC, methane and ethene dynamics in all microcosms tested. Modeling results describe that methanotrophic cometabolism of ethene promotes ethenotrophic VC cometabolism, which significantly enhances aerobic VC degradation in the presence of methane and ethene. This model is expected to be a useful tool to support effective and efficient processes for groundwater VC remediation.
Liu, Y, Ngo, HH, Guo, W, Zhou, J, Peng, L, Wang, D, Chen, X, Sun, J & Ni, B-J 2017, 'Optimizing sulfur-driven mixotrophic denitrification process: System performance and nitrous oxide emission', Chemical Engineering Science, vol. 172, pp. 414-422.
View/Download from: Publisher's site
View description>>
© 2017 Nitrate contamination of groundwater has been recognized as a significant environmental problem world widely. Sulfur-driven mixotrophic denitrification has been demonstrated as a promising groundwater treatment process, which though plays an important role in nitrous oxide (N2O) emissions, significantly contributing to the overall carbon footprint of the system. However, the current process optimizations only focus on nitrate removal and excess sulfate control, with the N2O emission being ignored. In this work, an integrated mathematical model was proposed to evaluate the N2O emission as well as the excess sulfate production and carbon source utilization in sulfur-driven mixotrophic denitrification process. In this model, autotrophic and heterotrophic denitrifiers use their corresponding electron donors (sulfur and organic matter, respectively) to reduce nitrate to nitrogen gas, with each modeled as three-step denitrification (NO3− to N2 via NO2− and N2O) driven by sulfur or organic matter to describe all potential N2O accumulation steps. The developed model, employing model parameters previously reported in literature, was successfully validated using N2O and sulfate data from two mixotrophic denitrification systems with different initial conditions. Modeling results revealed substantial N2O accumulation due to the relatively low autotrophic N2O reduction activity as compared to heterotrophic N2O reduction activity, explaining the observation that higher carbon source addition resulted in lower N2O accumulation in sulfur-driven mixotrophic denitrifying system. Based on the validated model, optimizations of the overall system performance were carried out. Application of the model to simulate long-term operations of sulfur-driven mixotrophic denitrification process indicates that longer sludge retention time reduces N2O emission due to better retention of active biomass. High-level total nitrogen removal with significant N2O emission mitigation, a...
Liu, Y, Pan, Y, Huang, D & Wang, Q 2017, 'Fault prognosis of filamentous sludge bulking using an enhanced multi-output gaussian processes regression', Control Engineering Practice, vol. 62, pp. 46-54.
View/Download from: Publisher's site
View description>>
The activated sludge process (ASP) is widely adopted to remove pollutants in wastewater treatment plants (WWTPs). However, the occurrence of filamentous sludge bulking often compromises the stable operation of the ASP. For timely diagnosis of filamentous sludge bulking for an activated sludge process in advance, this study proposed a Multi-Output Gaussian Processes Regression (MGPR) model for multi-step prediction and presented the Vector auto-regression (VAR) to learn the MGPR modelling deviation. The resulting models and associated uncertainty levels are used to monitor the filamentous sludge bulking related parameter, sludge volume index (SVI), such that the evolution of SVI can be predicted for both one-step and multi-step ahead. This methodology was validated with SVI data collected from one full-scale WWTP. Online diagnosis and prognosis of filamentous bulking sludge with real-time SVI prediction were tested through a simulation study. The results demonstrated that the proposed methodology was capable of predicting future SVI with good accuracy, thereby providing sufficient time for filamentous sludge bulking.
Liu, Y, Zhang, Y, Zhao, Z, Ngo, HH, Guo, W, Zhou, J, Peng, L & Ni, B-J 2017, 'A modeling approach to direct interspecies electron transfer process in anaerobic transformation of ethanol to methane', Environmental Science and Pollution Research, vol. 24, no. 1, pp. 855-863.
View/Download from: Publisher's site
View description>>
© 2016, Springer-Verlag Berlin Heidelberg. Recent studies have shown that direct interspecies electron transfer (DIET) plays an important part in contributing to methane production from anaerobic digestion. However, so far anaerobic digestion models that have been proposed only consider two pathways for methane production, namely, acetoclastic methanogenesis and hydrogenotrophic methanogenesis, via indirect interspecies hydrogen transfer, which lacks an effective way for incorporating DIET into this paradigm. In this work, a new mathematical model is specifically developed to describe DIET process in anaerobic digestion through introducing extracellular electron transfer as a new pathway for methane production, taking anaerobic transformation of ethanol to methane as an example. The developed model was able to successfully predict experimental data on methane dynamics under different experimental conditions, supporting the validity of the developed model. Modeling predictions clearly demonstrated that DIET plays an important role in contributing to overall methane production (up to 33 %) and conductive material (i.e., carbon cloth) addition would significantly promote DIET through increasing ethanol conversion rate and methane production rate. The model developed in this work will potentially enhance our current understanding on syntrophic metabolism via DIET.
Liu, Z, Ju, X, Wu, C & Liang, J 2017, 'Scattering of plane P 1 waves and dynamic stress concentration by a lined tunnel in a fluid-saturated poroelastic half-space', Tunnelling and Underground Space Technology, vol. 67, pp. 71-84.
View/Download from: Publisher's site
Liu, Z, Liang, J, Wu, C, Zhao, R & Li, Y 2017, 'The method of fundamental solution for elastic wave scattering and dynamic stress concentration in a fluid-saturated poroelastic layered half-plane', Engineering Analysis with Boundary Elements, vol. 84, pp. 154-167.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd A meshless method based on the method of fundamental solution (MFS) is developed to solve elastic-wave scattering and dynamic stress concentration in a fluid-saturated poroelastic layered half-plane, by utilizing the line sources of cylindrical P I , P II , and SV waves in a poroelastic layered half-plane. The numerical accuracy and stability of the MFS is verified by examining the boundary conditions and comparison with other methods. Subsequently, the amplification effects on displacement, surface hoop stress and fluid pore pressure around a cavity in a three-layered poroelastic half-plane are investigated. Numerical results indicate that the scattering characteristics strongly depend on parameters including the incident frequency and angle, soil-layer porosity and boundary drainage condition. The amplification effects of a cavity in the poroelastic layered half-plane appear to be more significant than the corresponding case of a homogenous half-plane. The amplitude of the fluid pore pressure on the surface of the cavity is amplified up to five times that of the free field, which also considerably aggravates the dynamic stress concentration around the cavity.
Loganathan, P, Naidu, G & Vigneswaran, S 2017, 'Mining valuable minerals from seawater: a critical review', Environmental Science: Water Research & Technology, vol. 3, no. 1, pp. 37-53.
View/Download from: Publisher's site
View description>>
Methods of extracting valuable minerals from seawater and seawater brines generated in desalination plants are critically reviewed in this paper.
Lotfi, F, Chekli, L, Phuntsho, S, Hong, S, Choi, JY & Shon, HK 2017, 'Understanding the possible underlying mechanisms for low fouling tendency of the forward osmosis and pressure assisted osmosis processes', Desalination, vol. 421, pp. 89-98.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. We investigated the possible underlying mechanism of the low fouling potential in the forward osmosis (FO) process during the osmotic dilution of seawater as part of the simultaneous desalination and wastewater reuse by FO and reverse osmosis hybrid system. Long-term experiments revealed an interesting water flux pattern highly dependent on the different operating parameters. The most interesting observation made was the spontaneous increase in the FO permeate flux at regular time interval during the FO operation using synthetic wastewater as feed and seawater. This sinusoidal FO flux pattern related well with the build-up of loose fouling layer and their natural peel-off from the membrane surface upon reaching certain layer thickness due to crossflow velocity shear. This flux pattern was more prominent at higher cross-flow velocity rates, lower feed water pH, for a smoother membrane surface and at lower operating pressure during pressure assisted osmosis (PAO) mode. Based on these results, membrane cleaning strategies were proposed by targeting a higher cross-flow velocity shear at a time when the permeate flux started to just increase. The approach of physical membrane cleaning was observed efficient and was able to almost fully restore the initial flux even under the PAO operation at 4 bar.
Luo, L, Duan, N, Wang, XC, Guo, W & Ngo, HH 2017, 'New thermodynamic entropy calculation based approach towards quantifying the impact of eutrophication on water environment', Science of The Total Environment, vol. 603-604, pp. 86-93.
View/Download from: Publisher's site
Luo, W, Phan, HV, Li, G, Hai, FI, Price, WE, Elimelech, M & Nghiem, LD 2017, 'An Osmotic Membrane Bioreactor–Membrane Distillation System for Simultaneous Wastewater Reuse and Seawater Desalination: Performance and Implications', Environmental Science & Technology, vol. 51, no. 24, pp. 14311-14320.
View/Download from: Publisher's site
Luo, W, Phan, HV, Xie, M, Hai, FI, Price, WE, Elimelech, M & Nghiem, LD 2017, 'Osmotic versus conventional membrane bioreactors integrated with reverse osmosis for water reuse: Biological stability, membrane fouling, and contaminant removal', Water Research, vol. 109, pp. 122-134.
View/Download from: Publisher's site
View description>>
This study systematically compares the performance of osmotic membrane bioreactor - reverse osmosis (OMBR-RO) and conventional membrane bioreactor - reverse osmosis (MBR-RO) for advanced wastewater treatment and water reuse. Both systems achieved effective removal of bulk organic matter and nutrients, and almost complete removal of all 31 trace organic contaminants investigated. They both could produce high quality water suitable for recycling applications. During OMBR-RO operation, salinity build-up in the bioreactor reduced the water flux and negatively impacted the system biological treatment by altering biomass characteristics and microbial community structure. In addition, the elevated salinity also increased soluble microbial products and extracellular polymeric substances in the mixed liquor, which induced fouling of the forward osmosis (FO) membrane. Nevertheless, microbial analysis indicated that salinity stress resulted in the development of halotolerant bacteria, consequently sustaining biodegradation in the OMBR system. By contrast, biological performance was relatively stable throughout conventional MBR-RO operation. Compared to conventional MBR-RO, the FO process effectively prevented foulants from permeating into the draw solution, thereby significantly reducing fouling of the downstream RO membrane in OMBR-RO operation. Accumulation of organic matter, including humic- and protein-like substances, as well as inorganic salts in the MBR effluent resulted in severe RO membrane fouling in conventional MBR-RO operation.
Lyu, M, Zhu, X & Yang, Q 2017, 'Bilinear connection stiffness identification of heritage timber buildings with limited strain measurements', Engineering Structures, vol. 151, pp. 665-681.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd ‘Que-Ti’ is an important component connecting the beam and column in typical Tibetan historic timber buildings. It transfers shear, compression and bending moment by slippage and deformation of components as well as a limited joint rotation. A rigorous analytical model of ‘Que-Ti’ is needed for predicting the behaviour of a timber structure under loading. However, few researches have been conducted in this area, particularly on the effect of key parameters on the performance of the joint under loading. In this paper, a new method has been proposed to identify both the thermal load on the structure and the bilinear connection stiffness of the semi-rigid joint from limited measured strain responses by integrating the temperature-based response sensitivity analysis with the dual Kalman filter. A novel bilinear rotational spring model has been developed for the joint to take into account the friction slip at the interface, the shear in the tenon, and the gap between the tenon and the mortise of the ‘Que-Ti’ in typical heritage Tibetan buildings. The semi-rigid connection is modeled as two bilinear rotational springs and one compressive spring. The temperature is treated as the input of the structure and the thermal loading on the structure can be determined based on the proposed method. The numerical results show that the method is effective and reliable to identify the thermal loading, unknown boundary conditions and the connection stiffness of the ‘Que-Ti’ accurately even with 10% noise in measurements. A long-term monitoring system has also been installed in a typical heritage Tibetan building and the monitoring data have been used to further verify the method. The experimental results show that the identified stiffness by the proposed method with bilinear connection stiffness model can get better results than that with linear connection stiffness model.
Lyu, M, Zhu, X & Yang, Q 2017, 'Condition assessment of heritage timber buildings in operational environments', Journal of Civil Structural Health Monitoring, vol. 7, no. 4, pp. 505-516.
View/Download from: Publisher's site
View description>>
© 2017, Springer-Verlag GmbH Germany. Due to changing environments and aging, the structural resistance of the heritage buildings has been reduced significantly. It has become crucial to monitor and protect the architectural heritage buildings. The objective of this research is to monitor and assess the performance of the heritage Tibetan timber building in operational environments. A three-storey corridor part of the typical heritage building was chosen in the study. A long-term monitoring system was installed in the building to collect the structural response and temperature. Detailed finite element model was built based on site investigation and existing documents, and updated based on the temperature-based response sensitivity using the field-monitoring data. The updated model was further evaluated using the static and dynamic analysis for condition assessment of the building in operational environments. The results show that the updated model is effective and accurate to predict the structural behaviour of the building in operational environments. Based on temperature-based response sensitivity, it is capable of tracking structure performance throughout the life-cycle allowing for condition-based maintenance and structural protection.
Lyu, M, Zhu, X & Yang, Q 2017, 'Connection stiffness identification of historic timber buildings using Temperature-based sensitivity analysis', Engineering Structures, vol. 131, pp. 180-191.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd The beam-column connection, called ‘Que Ti’, is the key component of historic Tibetan timber buildings to transfer shear, compression and bending loads from one structural element to another. This kind of connections can reduce the internal forces and improve the structure's ability to resist earthquakes. Its structure is very complicated and there is little information about the behaviour of this kind of semi-rigid connections. In this paper, a temperature-based response sensitivity method is proposed to identify the connection stiffness of the ‘Que-Ti’ in typical historical Tibetan buildings from temperature and strain response measurements. The semi-rigid connection is modeled as two rotational springs and one compressive spring. The temperature is treated as a measurable input and the thermal loading on the structure can be determined from the temperature variation. The numerical results show the method is effective and reliable to identify both unknown boundary conditions and the connection stiffness of the structure accurately even with 10% noise in measurements. A long-term monitoring system has also been installed in a typical historical Tibetan building and the monitoring data are used to further verify the proposed method. The experimental results show that the identified stiffnesses by the proposed method are consistent with that by finite element model updating from ambient vibration measurements.
Ma, B, Yang, L, Wang, Q, Yuan, Z, Wang, Y & Peng, Y 2017, 'Inactivation and adaptation of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria when exposed to free nitrous acid', Bioresource Technology, vol. 245, no. Pt A, pp. 1266-1270.
View/Download from: Publisher's site
View description>>
Inactivation and adaptation of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) to free nitrous acid (FNA) was investigated. Batch test results showed that AOB and NOB were inactivated when treated with FNA. After an 85-day operating period, AOB in a continuous pre-denitrification reactor did not adapt to the FNA that was applied to treat some of the return activated sludge. In contrast, NOB did adapt to FNA. NOB activity in the seed sludge was only 11% of the original activity after FNA batch treatment, at 0.75mg HNO2-N/L. NOB activity in the pre-denitrification reactor was not affected after being exposed to this FNA level. Nitrosomonas was the dominant AOB before and after long-term FNA treatment. However, dominant NOB changed from Nitrospira to Candidatus Nitrotoga, a novel NOB genus, after long-term FNA treatment. This adaptation of NOB to FNA may be due to the shift in NOB population makeup.
Mahlia, TMI, Masjuki, HH, Choudhury, IA & R. Saidur, ARS 2017, 'A review on energy efficiency standards and labels: present status and implementation possibilities in malaysia', ASEAN Journal on Science and Technology for Development, vol. 18, no. 1, pp. 71-84.
View/Download from: Publisher's site
View description>>
This article is a review on energy efficiency standards and labels for household electrical appliances around the world. Through the review of other country experiences on energy efficiency standards and labels, we attempt to identify savings possibilities in Malaysian households. The implementation possibilities of standards and labels for various household electrical appliances in Malaysia are also examined. It is found that various household appliances in Malaysia offer some potential in reducing electricity consumption. Finally, it is concluded that there are many advantages for Malaysia to implement the standards and labels for household electrical appliances as soon as possible in order to reduce electricity bills and energy consumption in Malaysian households.
Makki Alamdari, M, Samali, B, Li, J, Lu, Y & Mustapha, S 2017, 'Structural condition assessment using entropy-based time series analysis', Journal of Intelligent Material Systems and Structures, vol. 28, no. 14, pp. 1941-1956.
View/Download from: Publisher's site
View description>>
We present a time-series-based algorithm to identify structural damage in the structure. The method is in the context of non-model-based approaches; hence, it eliminates the need of any representative numerical model of the structure to be built. The method starts by partitioning the state space into a finite number of subsets which are mutually exclusive and exhaustive and each subset is identified by a distinct symbol. Partitioning is performed based on a maximum entropy approach which takes into account the sparsity and distribution of information in the time series. After constructing the symbol space, the time series data are uniquely transformed from the state space into the constructed symbol space to create the symbol sequences. Symbol sequences are the simplified abstractions of the complex system and describe the evolution of the system. Each symbol sequence is statistically characterized by its entropy which is obtained based on the probability of occurrence of the symbols in the sequence. As a consequence of damage occurrence, the entropy of the symbol sequences changes; this change is implemented to define a damage indicative feature. The method shows promising results using data from two experimental case studies subject to varying excitation. The first specimen is a reinforced concrete jack arch which replicates one of the major structural components of the Sydney Harbor Bridge and the second specimen is a three-story frame structure model which has been tested at Los Alamos National Laboratory. The method not only could successfully identify the presence of damage but also has potential to localize it.
Manjunath, SV, Kumar, SM, Ngo, HH & Guo, W 2017, 'Metronidazole removal in powder-activated carbon and concrete-containing graphene adsorption systems: Estimation of kinetic, equilibrium and thermodynamic parameters and optimization of adsorption by a central composite design', Journal of Environmental Science and Health, Part A, vol. 52, no. 14, pp. 1269-1283.
View/Download from: Publisher's site
View description>>
Metronidazole (MNZ) removal by two adsorbents, i.e., concrete-containing graphene (CG) and powder-activated carbon (PAC), was investigated via batch-mode experiments and the outcomes were used to analyze the kinetics, equilibrium and thermodynamics of MNZ adsorption. MNZ sorption on CG and PAC has followed the pseudo-second-order kinetic model, and the thermodynamic parameters revealed that MNZ adsorption was spontaneous on PAC and non-spontaneous on CG. Subsequently, two-parameter isotherm models, i.e., Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Elovich models, were applied to evaluate the MNZ adsorption capacity. The maximum MNZ adsorption capacities ([Formula: see text]) of PAC and CG were found to be between 25.5-32.8 mg/g and 0.41-0.002 mg/g, respectively. Subsequently, the effects of pH, temperature and adsorbent dosage on MNZ adsorption were evaluated by a central composite design (CCD) approach. The CCD experiments have pointed out the complete removal of MNZ at a much lower PAC dosage by increasing the system temperature (i.e., from 20°C to 40°C). On the other hand, a desorption experiment has shown 3.5% and 1.7% MNZ removal from the surface of PAC and CG, respectively, which was insignificant compared to the sorbed MNZ on the surface by adsorption. The overall findings indicate that PAC and CG with higher graphene content could be useful in MNZ removal from aqueous systems.
Mannan, A, Mohd Sabri, MF, Kalam, MA & Masjuki, HH 2017, 'Tribological properties of hydrogen free DLC in self-mated contacts against ZDDP-added oil', Industrial Lubrication and Tribology, vol. 69, no. 6, pp. 938-944.
View/Download from: Publisher's site
View description>>
Purpose
The purpose of this study is to investigate the tribological properties of tetrahedral diamond-like carbon (DLC) films in self-mated contacts in the presence of additivated and non-additivated vegetable oils. DLC films have high practical value due to low friction and low wear properties. On the other hand, vegetable oils are considered to be lubricants for future due to its resource renewability and biodegradability. Sometimes different chemical agents are added to vegetable oils to further improve its tribological properties. Thus, the tribological study of DLC films against additivated oils becomes important.
Design/methodology/approach
The tribology tests were conducted in a four ball tribo-meter under the boundary lubricated conditions.
Findings
Ta-C DLC exhibited 80 per cent lower wear rate under Zinc dialkyldithiophosphates (ZDDP)-added oil compared to that of base oil. In contrast, the friction coefficient under additivated oil was slightly higher than the base oil lubricated case. Moreover, the carbonyl band area as well as the viscosity change of ZDDP-added oil was much smaller than that of base oil. Therefore, ZDDP reduced the wear of DLC film and prevented the oxidation of base oil during tribotests.
Originality/value
This is the first work on the tribological properties of ta-C DLC lubricated with corn oil with and without anti-wear additives.
Mardhiah, HH, Ong, HC, Masjuki, HH, Lim, S & Lee, HV 2017, 'A review on latest developments and future prospects of heterogeneous catalyst in biodiesel production from non-edible oils', Renewable and Sustainable Energy Reviews, vol. 67, pp. 1225-1236.
View/Download from: Publisher's site
Mardhiah, HH, Ong, HC, Masjuki, HH, Lim, S & Pang, YL 2017, 'Investigation of carbon-based solid acid catalyst from Jatropha curcas biomass in biodiesel production', Energy Conversion and Management, vol. 144, pp. 10-17.
View/Download from: Publisher's site
McKenzie, TG, Colombo, E, Fu, Q, Ashokkumar, M & Qiao, GG 2017, 'Sono‐RAFT Polymerization in Aqueous Medium', Angewandte Chemie International Edition, vol. 56, no. 40, pp. 12302-12306.
View/Download from: Publisher's site
View description>>
AbstractThe ultrasonic irradiation of aqueous solution is demonstrated to be a suitable source of initiating radicals for a controlled radical polymerization when conducted in the presence of a thiocarbonylthio‐containing reversible addition–fragmentation chain transfer (RAFT) agent. This allows for a highly “green” method of externally regulated/controlled polymerization with a potentially broad scope for polymerizable monomers and/or polymer structures.
Mei, P, Pramanik, M, Young, C, Huang, Z, Hossain, MSA, Sugahara, Y & Yamauchi, Y 2017, 'Synthesis of mesostructured manganese phosphonate and its promising energy storage application', Journal of Materials Chemistry A, vol. 5, no. 44, pp. 23259-23266.
View/Download from: Publisher's site
View description>>
Mesostructured manganese phosphonate (MnP) with a uniform nanorod morphology has been prepared through an easy surfactant-mediated procedure.
Meng, J, Huang, J, Sheng, D & Sloan, SW 2017, 'Granular contact dynamics with elastic bond model', Acta Geotechnica, vol. 12, no. 3, pp. 479-493.
View/Download from: Publisher's site
Meng, J, Huang, J, Sheng, D & Sloan, SW 2017, 'Quasi-Static Rheology of Granular Media Using the Static DEM', International Journal of Geomechanics, vol. 17, no. 11, pp. 04017094-04017094.
View/Download from: Publisher's site
Mezaal, MR, Pradhan, B, Sameen, MI, Mohd Shafri, HZ & Yusoff, ZM 2017, 'Optimized Neural Architecture for Automatic Landslide Detection from High‐Resolution Airborne Laser Scanning Data', Applied Sciences, vol. 7, no. 7, pp. 730-730.
View/Download from: Publisher's site
View description>>
An accurate inventory map is a prerequisite for the analysis of landslide susceptibility, hazard, and risk. Field survey, optical remote sensing, and synthetic aperture radar techniques are traditional techniques for landslide detection in tropical regions. However, such techniques are time consuming and costly. In addition, the dense vegetation of tropical forests complicates the generation of an accurate landslide inventory map for these regions. Given its ability to penetrate vegetation cover, high-resolution airborne light detection and ranging (LiDAR) has been used to generate accurate landslide maps. This study proposes the use of recurrent neural networks (RNN) and multi-layer perceptron neural networks (MLP-NN) in landscape detection. These efficient neural architectures require little or no prior knowledge compared with traditional classification methods. The proposed methods were tested in the Cameron Highlands, Malaysia. Segmentation parameters and feature selection were respectively optimized using a supervised approach and correlation-based feature selection. The hyper-parameters of network architecture were defined based on a systematic grid search. The accuracies of the RNN and MLP-NN models in the analysis area were 83.33% and 78.38%, respectively. The accuracies of the RNN and MLP-NN models in the test area were 81.11%, and 74.56%, respectively. These results indicated that the proposed models with optimized hyper-parameters produced the most accurate classification results. LiDAR-derived data, orthophotos, and textural features significantly affected the classification results. Therefore, the results indicated that the proposed methods have the potential to produce accurate and appropriate landslide inventory in tropical regions such as Malaysia.
Mezaal, MR, Pradhan, B, Shafri, HZM & Yusoff, ZM 2017, 'Automatic landslide detection using Dempster–Shafer theory from LiDAR-derived data and orthophotos', Geomatics, Natural Hazards and Risk, vol. 8, no. 2, pp. 1935-1954.
View/Download from: Publisher's site
View description>>
© 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. A good landslide inventory map is a prerequisite for landslide hazard and risk analysis. In tropical countries, such as Malaysia, preparation of the landslide inventory is a challenging task because of the rapid growth of vegetation. Thus, it is crucial to use rapid and accurate technique and effective parameters. For this purpose, Dempster Shafer theory (DST) was applied in fusing high resolution LiDAR derived data products and Greenness index derived from orthophoto imagery. Two sites were selected, for the implementation and evaluation of the DST model; site “A” for DST implementation and site “B” for the comparison. For model implementation, vegetation index, slope and height were used as effective parameters for identifying automatic landslide detection. Two type of DST based fusions were evaluated; (greenness and height) and (greenness and slope). Furthermore, validation techniques were used to validate the accuracy are confusion matrix and area under the curve. The overall accuracy of the first and second evaluated fusions were (73.4% and 84.33%), and area under the curve were (0.76 and 0.81) respectively. Additionally, the result was compa red with Random Forest (RF) based detection approach. The results showed that DST does not require a priori knowledge.
Mirzaghorbanali, A, Rasekh, H, Aziz, N, Yang, G, Khaleghparast, S & Nemcik, J 2017, 'Shear strength properties of cable bolts using a new double shear instrument, experimental study, and numerical simulation', Tunnelling and Underground Space Technology, vol. 70, pp. 240-253.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd A newly developed double shear apparatus without contact between concrete blocks was developed to conduct a series of double shear tests. This new double shear apparatus is capable of determining the pure shear strength of pre-tensioned fully grouted cable bolt without friction between sheared concrete blocks. Five different types of cable bolt, with various pretension loads, were tested to investigate the influence of surface profile type and pretension load on the shear strength of cable bolt. Concrete blocks of 40 MPa strength and the Stratabinder HS grout were used for consistency across the entire tests. The results showed that the plain cable bolts had higher peak shear load compared with the indented and spiral strand cable bolts. The shear displacement and peak shear load decreased by increasing the pretension load. A numerical analysis was carried out, based on the Fast Lagrangian Analysis of Continua (FLAC 2D) and the result was compared with the experimental data. It was observed that FLAC 2D is capable of simulating the performance of cable bolt satisfactorily.
Mojaddadi, H, Pradhan, B, Nampak, H, Ahmad, N & Ghazali, AHB 2017, 'Ensemble machine-learning-based geospatial approach for flood risk assessment using multi-sensor remote-sensing data and GIS', Geomatics, Natural Hazards and Risk, vol. 8, no. 2, pp. 1080-1102.
View/Download from: Publisher's site
View description>>
© 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. In this paper, an ensemble method, which demonstrated efficiency in GIS based flood modeling, was used to create flood probability indices for the Damansara River catchment in Malaysia. To estimate flood probability, the frequency ratio (FR) approach was combined with support vector machine (SVM) using a radial basis function kernel. Thirteen flood conditioning parameters, namely, altitude, aspect, slope, curvature, stream power index, topographic wetness index, sediment transport index, topographic roughness index, distance from river, geology, soil, surface runoff, and land use/cover (LULC), were selected. Each class of conditioning factor was weighted using the FR approach and entered as input for SVM modeling to optimize all the parameters. The flood hazard map was produced by combining the flood probability map with flood-triggering factors such as; averaged daily rainfall and flood inundation depth. Subsequently, the hydraulic 2D high-resolution sub-grid model (HRS) was applied to estimate the flood inundation depth. Furthermore, vulnerability weights were assigned to each element at risk based on their importance. Finally flood risk map was generated. The results of this research demonstrated that the proposed approach would be effective for flood risk management in the study area along the expressway and could be easily replicated in other areas.
Mojumder, JC, Ong, HC, Chong, WT, Izadyar, N & Shamshirband, S 2017, 'The intelligent forecasting of the performances in PV/T collectors based on soft computing method', Renewable and Sustainable Energy Reviews, vol. 72, pp. 1366-1378.
View/Download from: Publisher's site
Mojumder, JC, Ong, HC, Chong, WT, Leong, KY & Izadyar, N 2017, 'An empirical analysis on photovoltaic thermal system with fin design by forced air circulation', Journal of Mechanical Science and Technology, vol. 31, no. 5, pp. 2549-2557.
View/Download from: Publisher's site
Mokhtar, ES, Pradhan, B, Ghazali, AH & Shafri, HZM 2017, 'Comparative assessment of water surface level using different discharge prediction models', Natural Hazards, vol. 87, no. 2, pp. 1125-1146.
View/Download from: Publisher's site
View description>>
Discharge is traditionally measured at gauge stations located at discrete positions along the river course. When the volume of water discharge is higher than the river bank, inundation to adjacent land occurs. Flood inundation mapping has largely relied on in situ discharge data. However, it cannot be accessed at ungauged sites. In recent literature, no comparative study on the impact of water level using different discharge models has been carried out. This paper evaluates the performance of three empirical formulas for discharge measurement to model flood inundation along Padang Terap River in Kedah, Malaysia, between October 31, 2010 and November 4, 2010. Water discharge was computed using three models, and the Manning-n values were assigned to the types of land use. Further, the rainfall obtained from gauge stations was interpolated using the Kriging interpolation method. Relative error and RMSE methods were used to evaluate the measured and predicted water surface elevation. The impact of predicted water surface elevation (WSE) from different land use types and terrain information was assessed. Dingman and Sharma’s model significantly presented good agreement between measured and predicted WSE with R 2 = 0.8034, followed by Manning and Bjerklie equations with 0.8024 and 0.7997, respectively. Moreover, Dingman and Sharma’s model produced less RE and RMSE with 13.09% and 2.27 m compared with the others. Therefore, the estimated discharge can be used in ungauged sites for flood inundation modeling. Manning-n, elevation, and slope affected the WSE.
Monirul, IM, Kalam, MA, Masjuki, HH, Zulkifli, NWM, Shahir, SA, Mosarof, MH & Ruhul, AM 2017, 'Influence of poly(methyl acrylate) additive on cold flow properties of coconut biodiesel blends and exhaust gas emissions', Renewable Energy, vol. 101, pp. 702-712.
View/Download from: Publisher's site
View description>>
Biodiesel comprises fatty acid esters and is used as an alternative fuel for diesel engines. However, biodiesel has poor cold flow properties (i.e., CP, CFPP and PP) than mineral diesel fuel. This study aims to reduce the PP, CFPP and CP of coconut biodiesel (CB) blends using poly(methyl acrylate) (PMA) additives and investigate their effects on single-cylinder four-stroke diesel engine performance and exhaust gas emission. DSC and TGA were used to observe crystal behavior and thermal stability of the biodiesel fuel blends. Engine performance and emission were analyzed by Dynomax-2000 software and gas analyzer, respectively. Results showed that 20% of CB blended with diesel and 0.03 wt% of PMA showed significant improvement in the PP, CFPP and CP. Other properties of B20 with additives met the requirements of ASTM D6751. The BSFC of B20 with PMA was reduced by 3.247%, whereas the BTE was increased by 2.16%, compared with those of B20. Burning B20 with PMA increased the NO emission by 2.15%, whereas HC, CO and smoke emissions were 19.81%, 13.35% and 3.93% lower than those of B20, respectively. Therefore, CB20 blend with 0.03 wt% PMA can be used as an alternative fuel in cold regions without compromising fuel quality.
Monirul, IM, Masjuki, HH, Kalam, MA, Zulkifli, NWM & Shancita, I 2017, 'Influence of polymethyl acrylate additive on the formation of particulate matter and NOX emission of a biodiesel–diesel-fueled engine', Environmental Science and Pollution Research, vol. 24, no. 22, pp. 18479-18493.
View/Download from: Publisher's site
Moore, I, Sheng, D & Lake, C 2017, 'Note of appreciation / Note de reconnaissance', Canadian Geotechnical Journal, vol. 54, no. 12, pp. v-vii.
View/Download from: Publisher's site
Murray, A, Gilbert, RI & Castel, A 2017, 'A New Approach to Modeling Tension Stiffening in Reinforced Concrete', ACI Structural Journal, vol. 115, no. 1, pp. 127-137.
View/Download from: Publisher's site
View description>>
A novel approach to the modeling of tension stiffening is proposed based on considerations of the highly non-uniform strain regions that occur in the concrete surrounding embedded reinforcement bars near the primary cracks. A finite element study is undertaken to determine the effect of these disturbed regions on the overall deformation of reinforced concrete tension members. Simple hand calculations are presented to determine an effective cross-sectional area of concrete, which describes the overall contribution to axial rigidity of the cracked concrete for the ideal case of perfect bond. A scalar damage parameter is then introduced to account for the additional reduction in the tension stiffening effect caused by deterioration of bond at the reinforcement-concrete interface. Experimental tension stiffening studies in the literature (including a recent study by the authors) are used to calibrate the evolution of interface damage according to factors such as applied loading and shrinkage.
Naghibi, SA, Moghaddam, DD, Kalantar, B, Pradhan, B & Kisi, O 2017, 'A comparative assessment of GIS-based data mining models and a novel ensemble model in groundwater well potential mapping', Journal of Hydrology, vol. 548, pp. 471-483.
View/Download from: Publisher's site
View description>>
In recent years, application of ensemble models has been increased tremendously in various types of natural hazard assessment such as landslides and floods. However, application of this kind of robust models in groundwater potential mapping is relatively new. This study applied four data mining algorithms including AdaBoost, Bagging, generalized additive model (GAM), and Naive Bayes (NB) models to map groundwater potential. Then, a novel frequency ratio data mining ensemble model (FREM) was introduced and evaluated. For this purpose, eleven groundwater conditioning factors (GCFs), including altitude, slope aspect, slope angle, plan curvature, stream power index (SPI), river density, distance from rivers, topographic wetness index (TWI), land use, normalized difference vegetation index (NDVI), and lithology were mapped. About 281 well locations with high potential were selected. Wells were randomly partitioned into two classes for training the models (70% or 197) and validating them (30% or 84). AdaBoost, Bagging, GAM, and NB algorithms were employed to get groundwater potential maps (GPMs). The GPMs were categorized into potential classes using natural break method of classification scheme. In the next stage, frequency ratio (FR) value was calculated for the output of the four aforementioned models and were summed, and finally a GPM was produced using FREM. For validating the models, area under receiver operating characteristics (ROC) curve was calculated. The ROC curve for prediction dataset was 94.8, 93.5, 92.6, 92.0, and 84.4% for FREM, Bagging, AdaBoost, GAM, and NB models, respectively. The results indicated that FREM had the best performance among all the models. The better performance of the FREM model could be related to reduction of over fitting and possible errors. Other models such as AdaBoost, Bagging, GAM, and NB also produced acceptable performance in groundwater modelling. The GPMs produced in the current study may facilitate groundwater exploitati...
Naidu, G, Jeong, S, Choi, Y & Vigneswaran, S 2017, 'Membrane distillation for wastewater reverse osmosis concentrate treatment with water reuse potential', Journal of Membrane Science, vol. 524, pp. 565-575.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Membrane distillation (MD) was evaluated as a treatment option of wastewater reverse osmosis concentrate (WWROC) discharged from wastewater reclamation plants (WRPs). A direct contact MD (DCMD), at obtaining 85% water recovery of WWROC showed only 13–15% flux decline and produced good quality permeate (10–15 µS/cm, 99% ion rejection) at moderate feed temperature of 55 °C. Prevalent calcium carbonate (CaCO 3 ) deposition on the MD membrane occurred in treating WWROC at elevated concentrations. The combination of low salinity and loose CaCO 3 adhesion on the membrane did not significantly contribute to DCMD flux decline. Meanwhile, high organic content in WWROC (58–60 mg/L) resulted in a significant membrane hydrophobicity reduction (70% lower water contact angle than virgin membrane) attributed to low molecular weight organic adhesion onto the MD membrane. Granular activated carbon (GAC) pretreatment helped in reducing organic contents of WWROC by 46–50%, and adsorbed a range of hydrophobic and hydrophilic micropollutants. This ensured high quality water production by MD (micropollutants-free) and enhanced its reuse potential. The MD concentrated WWROC was suitable for selective ion precipitation, promising a near zero liquid discharge in WRPs.
Naidu, G, Jeong, S, Johir, MAH, Fane, AG, Kandasamy, J & Vigneswaran, S 2017, 'Rubidium extraction from seawater brine by an integrated membrane distillation-selective sorption system', Water Research, vol. 123, pp. 321-331.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The ultimate goal of seawater reverse osmosis (SWRO) brine management is to achieve minimal liquid discharge while recovering valuable resources. The suitability of an integrated system of membrane distillation (MD) with sorption for the recovery of rubidium (Rb+) and simultaneous SWRO brine volume reduction has been evaluated for the first time. Polymer encapsulated potassium copper hexacyanoferrate (KCuFC(PAN)) sorbent exhibited a good selectivity for Rb+ sorption with 10–15% increment at 55 °C (Langmuir Qmax = 125.11 ± 0.20 mg/g) compared to at 25 °C (Langmuir Qmax = 108.71 ± 0.20 mg/g). The integrated MD-KCuFC(PAN) system with periodic membrane cleaning, enabled concentration of SWRO brine to a volume concentration factor (VCF) of 2.9 (65% water recovery). A stable MD permeate flux was achieved with good quality permeate (conductivity of 15–20 μS/cm). Repeated cycles of MD-KCuFC(PAN) sorption with SWRO brine enabled the extraction of 2.26 mg Rb+ from 12 L of brine (equivalent to 1.9 kg of Rb/day, or 0.7 tonne/yr from a plant producing 10,000 m3/day brine). KCuFC(PAN) showed a high regeneration and reuse capacity. NH4Cl air stripping followed by resorcinol formaldehyde (RF) resin filtration enabled to recover Rb+ from the desorbed solution.
Naidu, G, Shim, WG, Jeong, S, Choi, Y, Ghaffour, N & Vigneswaran, S 2017, 'Transport phenomena and fouling in vacuum enhanced direct contact membrane distillation: Experimental and modelling', Separation and Purification Technology, vol. 172, pp. 285-295.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. The application of vacuum to direct contact membrane distillation (vacuum enhanced direct contact membrane distillation, V-DCMD) removed condensable gasses and reduced partial pressure in the membrane pores, achieving 37.6% higher flux than DCMD at the same feed temperature. Transfer mechanism and temperature distribution profile in V-DCMD were studied. The empirical flux decline (EFD) model represented fouling profiles of V-DCMD. In a continuous V-DCMD operation with moderate temperature (55 °C) and permeate pressure (300 mbar) for treating wastewater ROC, a flux of 16.0 ± 0.3 L/m 2 h and high quality distillate were achieved with water flushing, showing the suitability of V-DCMD for ROC treatment.
Nam, E, Wong, EHH, Tan, S, Fu, Q, Blencowe, A & Qiao, GG 2017, 'Antifogging Surface Facilitated by Nanoscale Coatings with Controllable Hydrophobicity and Cross‐Linking Density', Macromolecular Materials and Engineering, vol. 302, no. 1, pp. 1600199-1600199.
View/Download from: Publisher's site
View description>>
Antifogging and frost-resistant coatings can be used in a wide range of applications and enable high light transmission through substrates even under changes in environmental conditions. In this study, surface confined and cross-linked antifogging thin films are fabricated on glass slides via catalyst induced cross-linking (CIC), which has been recently introduced as an easy and efficient cross-linking methodology. Four different poly(ethylene glycol) (PEG)-based polymers with different hydrophilicity are synthesized and used to prepare films via CIC. Films prepared from the most hydrophilic PEG-based polymers display the best antifogging performances when exposed to a temperature change from −20 to 22 °C. Furthermore, several parameters including cross-linking density, surface roughness, hydrophobicity, and exposure time are also evaluated in terms of film transparency. Through these measurements, it is determined that, more loosely cross-linked films retain antifogging ability for longer time periods due to higher film swellability as compared to, more highly cross-linked films. This study signifies the crucial role of the film cross-linking density and hydrophilicity on the antifogging function. (Figure presented.).
Navaratnarajah, SK & Indraratna, B 2017, 'Use of Rubber Mats to Improve the Deformation and Degradation Behavior of Rail Ballast under Cyclic Loading', Journal of Geotechnical and Geoenvironmental Engineering, vol. 143, no. 6, pp. 04017015-04017015.
View/Download from: Publisher's site
Neshat, A & Pradhan, B 2017, 'Evaluation of groundwater vulnerability to pollution using DRASTIC framework and GIS', Arabian Journal of Geosciences, vol. 10, no. 22, pp. 1-8.
View/Download from: Publisher's site
View description>>
© 2017, Saudi Society for Geosciences. Groundwater management has a prominent role in the world especially in arid and semi-arid areas which have a shortage of water, and due to this serious problem, many researchers work on that for prevention and managing the water recourses to conserve and monitor sources. DRASTIC index can be put forward for estimating of groundwater vulnerability to such pollution. The main purpose of using the groundwater vulnerability model is to map groundwater susceptibility to pollution in different areas. However, this method has been used in various areas without modification, disregarding the effects of pollution type and characteristics. Thus, this technique must be standardized and approved for Kerman plain. Vulnerability evaluation to explain areas that are more vulnerable to contamination from anthropogenic sources has become a prominent element for land use planning and tangible resource management. This contribution aims at evaluating groundwater vulnerability by applying the DRASTIC index as well as employ sensitivity analyses to evaluate the comparative prominent of the model parameters for groundwater vulnerability in Kerman plain in the southeastern part of Iran. Moreover, the potential of vulnerability to pollution is more accurately assessed by optimizing the weights of the DRASTIC parameters with the single-parameter sensitivity analysis (SPSA). The new weights were calculated. The result of the study revealed that the DRASTIC-Sensitivity analysis exhibit more efficiently than the traditional method for a nonpoint source pollution. Observation of ultimate nitrate showed the result of DRASTIC-SPSA has more accuracy. The GIS method offers an efficient environment for carrying out assessments and greater capabilities for dealing with a huge quantity of spatial data.
Ngo, NT 2017, 'DEM MODELLING OF GEOCELL-STABILISED SUB-BALLAST UNDER CYCLIC LOADING', International Journal of GEOMATE, vol. 12, no. 31, pp. 23-29.
View/Download from: Publisher's site
View description>>
Upon repeated train loading, sub-ballast aggregates, placed underneath a ballast layer in rail track, become degraded and fouled by the progressive accumulation of external fine particles such as mud-pumping of soft subgrade, seriously decreasing the shear strength and drainage capacity of the track. This paper presents a study of the load-deformation response of geocell-reinforced sub-ballast under cyclic loads using laboratory tests and discrete element method (DEM). A series of large-scale cubical triaxial tests with and without geocell inclusions are conducted in the laboratory and simulated in DEM to investigate the beneficial effect of the geocells in decreasing the lateral and vertical deformations of railway subballast. Irregularly-shaped particles of sub-ballast are modelled by connecting and bonding of many circular balls together at appropriate sizes and positions. The geogcell was simulated by bonding many small spheres together to build a desired geometry and structure. The load-deformation behaviour of the geocell-stabilised sub-ballast specimen at varied load cycles predicted from the DEM modelling agrees well with those measured experimentally, showing that the proposed DEM model in this study is able to capture the deformation behaviour of the sub-ballast stabilised by the geocell. Additionally, the DEM modelling also provides insight into the distribution of contact forces, average contact normal and shear forces, which cannot be determined experimentally. These observations clearly prove the reinforcement effect of the geocell in eliminating the deformation of sub-ballast from a micromechanical perspective.
Ngo, NT, Indraratna, B & Rujikiatkamjorn, C 2017, 'A study of the geogrid–subballast interface via experimental evaluation and discrete element modelling', Granular Matter, vol. 19, no. 3, pp. 1-16.
View/Download from: Publisher's site
View description>>
This paper presents a study of the interface of geogrid reinforced subballast through a series of large-scale direct shear tests and discrete element modelling. Direct shear tests were carried out for subballast with and without geogrid inclusions under varying normal stresses of σn= 6.7 to 45kPa. Numerical modelling with three-dimensional discrete element method (DEM) was used to study the shear behaviour of the interface of subballast reinforced by geogrids. In this study, groups of 25–50 spherical balls are clumped together in appropriate sizes to simulate angular subballast grains, while the geogrid is modelled by bonding small spheres together to form the desired grid geometry and apertures. The calculated results of the shear stress ratio versus shear strain show a good agreement with the experimental data, indicating that the DEM model can capture the interface behaviour of subballast reinforced by geogrids. A micromechanical analysis has also been carried out to examine how the contact force distributions and fabric anisotropy evolve during shearing. This study shows that the shear strength of the interface is governed by the geogrid characteristics (i.e. their geometry and opening apertures). Of the three types of geogrid tested, triaxial geogrid (triangular apertures) exhibits higher interface shear strength than the biaxial geogrids; and this is believed due to multi-directional load distribution of the triaxial geogrid.
Ngo, NT, Indraratna, B & Rujikiatkamjorn, C 2017, 'Micromechanics-Based Investigation of Fouled Ballast Using Large-Scale Triaxial Tests and Discrete Element Modeling', Journal of Geotechnical and Geoenvironmental Engineering, vol. 143, no. 2, pp. 04016089-04016089.
View/Download from: Publisher's site
View description>>
Railway ballast comprises unbounded discrete grains that are often used to form a load-bearing platform for tracks. Ballast degradation as trains pass over the tracks and infiltration of external fines including slurried (pumped) fine subgrade soils are two of the main reasons for ballast fouling. Fouling causes tracks to settle and also reduces the load-bearing capacity, which is associated with a reduction in internal friction and increased lateral spreading of the ballast layer. This paper presents a study of mobilized friction angle, volumetric behavior, and associated evolutions of contact and fabric anisotropy of fouled ballast subjected to monotonic triaxial loading using a series of large-scale triaxial tests and discrete element modeling. Monotonically loaded and drained triaxial tests were carried out on ballast with levels of clay fouling that varied from 10 to 50% void contamination index (VCI) subjected to three confining pressures of 10, 30, and 60 kPa. The results showed that an increase in the level of fouling decreased the mobilized friction angle and increased the ballast dilation. The discrete element method (DEM) was used to study the mobilized friction angle and fabric anisotropy of fresh and fouled ballast by simulating actual large-scale triaxial tests. Irregular shaped grains of ballast were simulated by clumping bonded circular balls with appropriate sizes and positions together. Ballast fouling was approximately simulated in DEM by adding 1-mm particles into the pore spaces of the fresh ballast. The predicted mobilized friction angles and volumetric changes obtained from the DEM simulations agreed well with those measured in the laboratory, indicating that the peak friction angle of fouled ballast and dilation decreased as the degree of fouling increased. The DEM simulations provided an insight into the distribution of contact force chains, contact orientations, and evolution of fabric anisotropy of fresh and fouled ballast tha...
Ngo, NT, Indraratna, B & Rujikiatkamjorn, C 2017, 'Simulation Ballasted Track Behavior: Numerical Treatment and Field Application', International Journal of Geomechanics, vol. 17, no. 6, pp. 1-12.
View/Download from: Publisher's site
View description>>
The load deformation of ballasted rail tracks subjected to cyclic loading is investigated experimentally using a large-scale track process simulation apparatus and numerically through a combined discrete element-finite-difference approach. Laboratory tests were performed to examine the deformation and degradation of ballast subjected to cyclic loading at 15 Hz and a lateral confinement of 10 kPa. The laboratory results reveal that ballast undergoes significant deformation during the initial load cycles, followed by gradually increasing deformation attaining a steady value toward the end of testing. A numerical model based on a combined discrete element method (DEM) and finite-difference method (FDM) is introduced to study the load-deformation response of the ballast assembly while considering interaction between the ballast aggregates and the subgrade layer. In this coupled model, the discrete ballast grains are modeled by DEM, and the subgrade domain is modeled as a continuum by FDM. Interface elements are introduced to transmit the interacting forces and displacements between adjoining material domains in which the DEM transfers contact forces to the FDM, and then the FDM updates the displacements, which provides subsequent input into the DEM. This computational cycle continues with the increasing number of loading cycles. The numerical model is validated by comparing the predicted cyclic load-deformation response with the laboratory measurements. Contact force distributions and stress contours in the assembly are analyzed and presented graphically to interpret the behavior of the model track, and the effects that subgrade stiffness have on the axial strain and bond breakage of the ballast are investigated. This combined DEM-FDM analysis is also used to analyze the load deformation of an instrumented track in the town of Singleton, Australia, and the numerical predictions are compared with the field data.
Ngo, NT, Indraratna, B & Rujikiatkamjorn, C 2017, 'Stabilization of track substructure with geo-inclusions—experimental evidence and DEM simulation', International Journal of Rail Transportation, vol. 5, no. 2, pp. 63-86.
View/Download from: Publisher's site
View description>>
This article reviews on current knowledge of rail track geomechanics, including several important concepts and topics related to laboratory testing and computational modelling, to study the shear stress-strain and deformation of ballast improved by geosynthetics and recycled rubber mats. The effect that impact loads have on ballast degradation and its mitigation due to resilient synthetic mats (i.e. rubber mats) between the ballast and the subballast is investigated using large-scale impact-testing apparatus. Computational modelling with finite element and discrete element methods are increasingly being used to model ballasted tracks reinforced with geosynthetics to capture the continuum media of formation soils and the discrete nature of ballast aggregates. The article focuses on reviewing previous studies by the University of Wollongong on ballasted track substructure and highlights some practical implications whereby innovation progresses from theory to practice.
Nguyen, DD, Chang, SW, Cha, JH, Jeong, SY, Yoon, YS, Lee, SJ, Tran, MC & Ngo, HH 2017, 'Dry semi-continuous anaerobic digestion of food waste in the mesophilic and thermophilic modes: New aspects of sustainable management and energy recovery in South Korea', Energy Conversion and Management, vol. 135, pp. 445-452.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd In this study, parallel, bench-scale, mesophilic and thermophilic, dry, semi-continuous anaerobic digestion (DScAD) of Korea food waste (FW, containing 22% total solids (TS) and 20% volatile solids (VS)) was investigated thoroughly under varying operational conditions, including hydraulic retention times (HRTs) and organic loading rates (OLRs). The aim was to evaluate the start-up, stability, overall removal efficiency, and inhibitory effects of toxic compounds on process performance over a long-term operation lasting 100 days. The results from both digesters indicate that the simultaneous reduction of VS and the production of gas improved as the HRT decreased or the OLR increased. The highest average rates of VS reduction (79.67%) and biogas production (162.14 m 3 biogas/ton of FW, 61.89% CH 4 ), at an OLR of 8.62 ± 0.34 kg VS/m 3 day (25 days of HRT), were achieved under thermophilic DScAD. In addition, the average rates of reduction of VS and the production of biogas in thermophilic DScAD were higher by 6.88% and 16.4%, respectively, than were those in mesophilic DScAD. The inhibitory effects of ammonia, H 2 S, and volatile fatty acids (VFAs) on methane production was not clear from either of the digesters, although, apparently, their concentrations did fluctuate. This fluctuation could be attributed to the self-adaptation of the microbial well. However, digestion that was more stable and faster was observed under thermophilic conditions compared with that under mesophilic conditions. Based on our results, the optimum operational parameters to improve FW treatment and achieve higher energy yields could be determined, expanding the application of DScAD in treating organic wastes.
Nguyen, DD, Yeop, JS, Choi, J, Kim, S, Chang, SW, Jeon, B-H, Guo, W & Ngo, HH 2017, 'A new approach for concurrently improving performance of South Korean food waste valorization and renewable energy recovery via dry anaerobic digestion under mesophilic and thermophilic conditions', Waste Management, vol. 66, pp. 161-168.
View/Download from: Publisher's site
View description>>
Dry semicontinuous anaerobic digestion (AD) of South Korean food waste (FW) under four solid loading rates (SLRs) (2.30-9.21kg total solids (TS)/m(3)day) and at a fixed TS content was compared between two digesters, one each under mesophilic and thermophilic conditions. Biogas production and organic matter reduction in both digesters followed similar trends, increasing with rising SLR. Inhibitor (intermediate products of the anaerobic fermentation process) effects on the digesters' performance were not observed under the studied conditions. In all cases tested, the digesters' best performance was achieved at the SLR of 9.21kg TS/m(3)day, with 74.02% and 80.98% reduction of volatile solids (VS), 0.87 and 0.90m(3) biogas/kg VSremoved, and 0.65 (65% CH4) and 0.73 (60.02% CH4) m(3) biogas/kg VSfed, under mesophilic and thermophilic conditions, respectively. Thermophilic dry AD is recommended for FW treatment in South Korea because it is more efficient and has higher energy recovery potential when compared to mesophilic dry AD.
Nguyen, DD, Yoon, YS, Bui, XT, Kim, SS, Chang, SW, Guo, W & Ngo, HH 2017, 'Influences of operational parameters on phosphorus removal in batch and continuous electrocoagulation process performance', Environmental Science and Pollution Research, vol. 24, no. 32, pp. 25441-25451.
View/Download from: Publisher's site
View description>>
© 2017, Springer-Verlag GmbH Germany. Performance of an electrocoagulation (EC) process in batch and continuous operating modes was thoroughly investigated and evaluated for enhancing wastewater phosphorus removal under various operating conditions, individually or combined with initial phosphorus concentration, wastewater conductivity, current density, and electrolysis times. The results revealed excellent phosphorus removal (72.7–100%) for both processes within 3–6 min of electrolysis, with relatively low energy requirements, i.e., less than 0.5 kWh/m 3 for treated wastewater. However, the removal efficiency of phosphorus in the continuous EC operation mode was better than that in batch mode within the scope of the study. Additionally, the rate and efficiency of phosphorus removal strongly depended on operational parameters, including wastewater conductivity, initial phosphorus concentration, current density, and electrolysis time. Based on experimental data, statistical model verification of the response surface methodology (RSM) (multiple factor optimization) was also established to provide further insights and accurately describe the interactive relationship between the process variables, thus optimizing the EC process performance. The EC process using iron electrodes is promising for improving wastewater phosphorus removal efficiency, and RSM can be a sustainable tool for predicting the performance of the EC process and explaining the influence of the process variables.
Nguyen, DD, Yoon, YS, Nguyen, ND, Bach, QV, Bui, XT, Chang, SW, Le, HS, Guo, W & Ngo, HH 2017, 'Enhanced efficiency for better wastewater sludge hydrolysis conversion through ultrasonic hydrolytic pretreatment', Journal of the Taiwan Institute of Chemical Engineers, vol. 71, pp. 244-252.
View/Download from: Publisher's site
View description>>
© 2016 Taiwan Institute of Chemical Engineers.The major requirements for accelerating the process of anaerobic digestion and energy production are breaking the structure of waste activated sludge (WAS), and transforming it into a soluble form suitable for biodegradation. This work investigated and analysed a novel bench-scale ultrasonic system for WAS disruption and hydrolysis using ultrasonic homogenization. Different commercial sonoreactors were used at low frequencies under a variety of operating conditions (intensity, density, power, sonication time, and total suspended solids) to evaluate the effects of the equipment on sludge hydrolysis and to generate new insights into the empirical models and mechanisms applicable to the real-world processing of wastewater sludge. A relationship was established between the operating parameters and the experimental data. Results indicated an increase in sonication time or ultrasonic intensity correlated with improved sludge hydrolysis rates, sludge temperature, and reduction rate of volatile solids (33.51%). It also emerged that ultrasonication could effectively accelerate WAS hydrolysis to achieve disintegration within 5-10 min, depending on the ultrasonic intensity. This study also determined multiple alternative parameters to increase the efficiency of sludge treatment and organic matter reduction, and establish the practicality of applying ultrasonics to wastewater sludge pretreatment.
Nguyen, L, Fatahi, B & Khabbaz, H 2017, 'Development of a Constitutive Model to Predict the Behavior of Cement-Treated Clay during Cementation Degradation: C3 Model', International Journal of Geomechanics, vol. 17, no. 7, pp. 04017010-04017010.
View/Download from: Publisher's site
View description>>
© 2017 American Society of Civil Engineers. Many researchers have indicated how cementation allows treated soft clays to sustain a higher yield mean effective stress at the same void ratio as its reconstituted state, and thus, the strength of clay treated with cement increases because the cement and clay particles bond together. However, the void ratio of cement-treated clay decreases significantly in isotropic consolidation and triaxial conditions when subjected to a high mean effective stress, particularly beyond the initial yield stress. Laboratory experiments have shown that the cementation of clay gradually diminishes as the mean effective stress increases as a result of the degradation of cementation bonds. Thus, the failure envelope of cement-treated clay gradually merges with the reconstituted clay-cement mixture at high mean effective stresses. Furthermore, the shear strength of cement-treated clay is influenced by the shear degradation induced by shear deformation. In this study, by combining the mean effective stress and shear degradation, a constitutive model, referred to as the C3 model, based on the critical state framework, was developed to simulate the behavior of cement-treated clay. The proposed model includes a modified mean effective stress, a nonlinear failure envelope, a nonassociated plastic potential function, and a general stress-strain relationship to simulate the prepeak and postpeak deviatoric stress states, including the softening behavior of cement-treated clay. In this study, triaxial tests (drained and undrained) were conducted on Ballina clay treated with 10 and 12% cement and Kaolin clay treated with 5 and 10% cement, and the results are reported and discussed. The proposed model was evaluated by comparing its predictions with the triaxial test results reported on the cement-treated Ballina clay and Kaolin clay. The proposed constitutive model gave reliable predictions that agreed with the experimental results and captu...
Nguyen, TN, Nguyen, TT & Pansuk, W 2017, 'Experimental study of the punching shear behavior of high performance steel fiber reinforced concrete slabs considering casting directions', Engineering Structures, vol. 131, pp. 564-573.
View/Download from: Publisher's site
Nguyen, TT & Indraratna, B 2017, 'Experimental and numerical investigations into hydraulic behaviour of coir fibre drain', Canadian Geotechnical Journal, vol. 54, no. 1, pp. 75-87.
View/Download from: Publisher's site
View description>>
Over many decades, natural fibre bundles have been widely used for drainage and filtration applications because of their favourable hydraulic conductivity and abundance in Asian countries. In recent times, natural (biodegradable) coir and jute drains, which are environmentally friendly, have been considered in lieu of conventional geosynthetic wick drains for soft clay consolidation in Australian coastal regions. However, there is a lack of a computational framework to predict the hydraulic behaviour of fibre drains on the basis of micromechanical (fabric) characteristics. Employing computational fluid dynamics (CFD) coupled with the discrete element method (DEM) to model the hydraulic behaviour of fibrous materials has shown promise in an earlier 2016 study by Nguyen and Indraratna, which considered an idealized parallel arrangement of fibres for simplicity. This paper aims to broaden the application of the coupled CFD–DEM technique to real fibres (coconut coir) considering both nontwisted and twisted fibre bundles that have more complex porous structure. The hydraulic conductivity determined from the numerical approach is validated with the experimental results, and also compared with the analytical prediction based on the conventional Kozeny–Carmen (KC) approach. The current study shows that the CFD–DEM technique can capture well the fluid flow characteristics of a nonuniform fibrous structure, including dense twisted coir bundles.
Nguyen, TT & Indraratna, B 2017, 'The permeability of natural fibre drains, capturing their micro-features', Proceedings of the Institution of Civil Engineers - Ground Improvement, vol. 170, no. 3, pp. 123-136.
View/Download from: Publisher's site
View description>>
Natural fibres such as jute and coir are emerging as distinct alternatives to synthetic geomaterials, and in recent years they have been used increasingly for drainage and filtration in field applications. However, these naturally occurring materials are extremely variable in micro-characteristics such as the size, uniformity and shape of their fibres, while there is a lack of studies addressing how these differences can affect the hydraulic behaviour of fibrous media. This paper offers a laboratory study of the influence of micro-features on the hydraulic conductivity of fibre drain. Non-twisted and twisted fibre drains made from jute and coir were subjected to hydraulic conductivity testing and micro-analyses. Experimental results show a considerable contribution of the size characteristics of fibre to the hydraulic behaviour of the drain. A less-rounded shape of fibre and a larger twisting angle of the drain can increase the fluid–fibre contact area and the corresponding tortuosity of flow, which significantly reduces the drain permeability. The way in which the Kozeny–Carmen analytical approach can be adopted to predict the permeability of a fibre drain is discussed based on the experimental results, considering various micro-factors including the size of fibre, uniformity and the associated porosity.
Nguyen, T-T, Bui, X-T, Luu, V-P, Nguyen, P-D, Guo, W & Ngo, H-H 2017, 'Removal of antibiotics in sponge membrane bioreactors treating hospital wastewater: Comparison between hollow fiber and flat sheet membrane systems', Bioresource Technology, vol. 240, pp. 42-49.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Hollow fiber (HF) and flat sheet (FS) Sponge MBRs were operated at 10–20 LMH flux treating hospital wastewater. Simultaneous nitrification denitrification (SND) occurred considerably with TN removal rate of 0.011–0.020 mg TN mg VSS−1 d−1. Furthermore, there was a remarkable removal of antibiotics in both Sponge MBRs, namely Norfloxacin (93–99% (FS); 62–86% (HF)), Ofloxacin (73–93% (FS); 68–93% (HF)), Ciprofloxacin (76–93% (FS); 54–70% (HF)), Tetracycline (approximately 100% for both FS and HF) and Trimethoprim (60–97% (FS); 47–93% (HF). Whereas there was a quite high removal efficiency of Erythromycin in Sponge MBRs, with 67–78% (FS) and 22–48% (HF). Moreover, a slightly higher removal of antibiotics in FS than in HF achieved, with the removal rate being of 0.67–32.40 and 0.44–30.42 µg mg VSS−1 d−1, respectively. In addition, a significant reduction of membrane fouling of 2–50 times was achieved in HF-Sponge MBR for the flux range.
Norjannah, B, Ong, HC & Masjuki, HH 2017, 'Effects of methanol and enzyme pretreatment to Ceiba pentandra biodiesel production', Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 39, no. 14, pp. 1548-1555.
View/Download from: Publisher's site
Nur, T, Loganathan, P, Kandasamy, J & Vigneswaran, S 2017, 'Removal of strontium from aqueous solutions and synthetic seawater using resorcinol formaldehyde polycondensate resin', Desalination, vol. 420, pp. 283-291.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Strontium (Sr) is a valuable metal found in abundance in seawater. However, its recovery from seawater has received little attention despite its many industrial applications. Batch and column adsorption experiments were conducted on the removal of Sr by resorcinol formaldehyde (RF) resin in the presence of co-existing cations at pH 7.5–8.5, where maximum adsorption was found. Batch adsorption capacities of cations followed the decreasing order of Sr > Ca > Mg > K, the order being the same as that of reduction of negative zeta potential. The adsorption data for Sr, Ca and Mg satisfactorily fitted to the Langmuir adsorption model with maximum adsorption capacities of 2.28, 1.25 and 1.15 meq/g, respectively. Selectivity coefficients for Sr with respect to other metals showed that Sr was selectively adsorbed on RF. Column adsorption data for Sr only solution fitted well to the Thomas model. Sr adsorption capacity in the presence of seawater concentrations of Ca, Mg, K and Na was reduced in both batch and column experiments with highest effect from Ca and Mg. However, if Ca and Mg are removed prior to RF adsorption process by precipitation, the negative effect of these ions on Sr removal can be significantly reduced.
Nurhadi, M, Chandren, S, Yuan, LS, Ho, CS, Indra Mahlia, TM & Nur, H 2017, 'Titania-Loaded Coal Char as Catalyst in Oxidation of Styrene with Aqueous Hydrogen Peroxide', International Journal of Chemical Reactor Engineering, vol. 15, no. 1, pp. 45-55.
View/Download from: Publisher's site
View description>>
AbstractTitania-loaded coal char catalyst was successfully prepared. The preparation steps involved pyrolysis of low rank coal at different temperatures and durations, sulfonation, impregnation of titanium(IV) isopropoxide, and then heating at 110 °C. It is found that the coal chars’ surfaces were rough after sulfonation and impregnation, while large pore volume, high surface area and carbon composition were observed at low pyrolysis temperature for short duration. These properties contributed to high selectivity towards benzaldehyde (> 90 %) at 600 °C (0.5–2 h)) in styrene oxidation using aqueous hydrogen peroxide as the oxidant.
Olmati, P, Vamvatsikos, D & Stewart, MG 2017, 'Safety factor for structural elements subjected to impulsive blast loads', International Journal of Impact Engineering, vol. 106, pp. 249-258.
View/Download from: Publisher's site
View description>>
Design of blast loaded structures is usually carried out following a deterministic rather than a probabilistic approach. The design load scenario would cover the plausible load conditions (typically some conservative estimate) that a structure would experience if an explosion occurs but the probability that the structure will satisfy the design performances for the considered scenario remains unknown. Applying a performance-based design framework typically requires arduous Monte Carlo simulations, but a probabilistic design could also be achieved by a single structural analysis when consistent safety factors are applied to the load and the structural resistance. Such a factor is proposed herein for the case of components subjected to impulsive blast loads. The dependence of the safety factor on the amount of explosive, stand-off distance and their variability is estimated numerically and provided by means of regression formulas. A design example using the proposed safety factor is carried out and Monte Carlo simulation is used for verification. The results confirm the validity of the proposed safety factor approach and its applicability for the performance-based design of blast loaded structures using the current design practice methods.
Ong, ZC, Mohd Mishani, MB, Chong, WT, Soon, RS, Ong, HC & Ismail, Z 2017, 'Identification of optimum Calophyllum inophyllum bio-fuel blend in diesel engine using advanced vibration analysis technique', Renewable Energy, vol. 109, pp. 295-304.
View/Download from: Publisher's site
Pain, A, Chen, Q, Nimbalkar, S & Zhou, Y 2017, 'Evaluation of seismic passive earth pressure of inclined rigid retaining wall considering soil arching effect', Soil Dynamics and Earthquake Engineering, vol. 100, pp. 286-295.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Evaluation of seismic passive earth pressure is an important topic of research in geotechnical engineering. In this study seismic passive pressure on an inclined rigid retaining wall supporting horizontal cohesionless backfill is estimated considering arching effect. A planar failure surface is considered in the present analysis. Seismic forces are considered to be pseudo-static in nature. The effect of different parameters on the seismic passive earth pressure is studied in details. The normal stress distribution along the depth of the backfill is found to be nonlinear in nature. Friction angle between wall and the backfill soil has the most significant effect on the distribution of normal stress along the depth of the backfill. The point of application of seismic passive pressure shifts gradually downward for higher seismic forces. Present method is validated with the experimental results available in the literature for static conditions. Comparison of present method with other theories is also presented showing the merit of the present study. Arching effect in the backfill should be considered for high values of wall inclination angle as the present seismic passive resistance is found to be the lowest as compared to other theoretical solutions.
Panahian, M, Ghosh, S & Ding, G 2017, 'Assessing Potential for Reduction in Carbon Emissions in a Multi-unit of Residential Development in Sydney', Procedia Engineering, vol. 180, pp. 591-600.
View/Download from: Publisher's site
View description>>
© 2017 The Authors. There is an increase in the construction of multi-unit residential buildings around inner Sydney in the past few years. The energy consumption in Australia has increased by approximately 30% and associated carbon dioxide emissions. This research examines a large multi-unit residential case study located close to the Sydney's Central Business District (CBD). Current energy consumption for the common areas such as the basement, car parks, lobbies, etc. and water usage for gardens are estimated using the actual data on electricity and water usage. Potential for reduction in energy consumption and their equivalent carbon footprint values are examined. Three carbon emissions reduction strategies include: savings from electricity generation from roof solar PV installation; rainwater harvesting from the roof and minimising annual water loss by evaporation in swimming pools reducing energy demand for water supply. In addition, carbon benefits provided by the trees are calculated using an urban forest assessment tool. Recommendations suggest that installation of solar PV on the roof, using an appropriate swimming pool cover, rainwater harvesting and a better tree canopy cover collectively could improve the overall CO2 footprint performance of the selected case study.
Pang, T, Li, Y, Kang, H, Sun, G, Fang, J & Li, Q 2017, 'On functionally-graded crashworthy shape of conical structures for multiple load cases', Journal of Mechanical Science and Technology, vol. 31, no. 6, pp. 2861-2873.
View/Download from: Publisher's site
View description>>
© 2017, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany. Many studies on energy absorbers have been focused on tapered tubes because they have significant advantages in crashworthiness and provide a desired constant load-deflection response. However, few studies have been reported on tapered tubes with nonlinearlyvariable diameters along the longitudinal direction. This paper presents thin-walled Functionally graded tapered tube (FGTT) with a diameter varying nonlinearly subject to axial (0°) and oblique (10°, 20°, 30°) impacts. To explore the advantages of FGTT, conventional Straight/Conical circular tube (SCT/CCT) with the same mass are compared; and FGTTs with a gradient exponent n > 1 are found to be preferable to others in terms of energy absorption capacity under small impact angles. Then, crashworthiness analyses of different crushing distances are conducted and it is found that under a large impact angle (e.g. 20°, 30°), FGTT with a short crushing distance (e.g. 40 mm) have a higher mean crashing force than long crushing distance (e.g. 120 mm), especially for n > 1. In addition, the effect of geometric parameters, such as the gradient exponent n and diameter range ΔD between top (incident) and bottom (distal) diameters of FGTTs, are also studied and it is found that the FGTT with ΔD = 40 mm and n > 1 exhibits better crashworthiness than the others under small impact angles (0°, 10°). This paper demonstrates that such FGTT structures have a certain potential to be an energy absorber.
Pansuk, W, Nguyen, TN, Sato, Y, Den Uijl, JA & Walraven, JC 2017, 'Shear capacity of high performance fiber reinforced concrete I-beams', Construction and Building Materials, vol. 157, pp. 182-193.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd An experimental program was carried out to investigate the shear capacity of High-Performance Fiber-Reinforced Concrete (HPFRC) I-beams. The main parameters were assigned as the fiber content and presence of shear reinforcement. To study the effect of these main parameters on the shear capacity, testing of six I-beams and other control specimens was conducted. It can be observed from the results of the experimental study that the presence of fibers and shear reinforcement significantly improves the ultimate capacity and structural behavior of HPFRC members. Finally, the experimental results are discussed, and the shear capacity of HPFRC can be estimated by extending the code provisions stated in AFGC-Sétra 2013.
Pathak, N, Chekli, L, Wang, J, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, T & Shon, H 2017, 'Performance of a novel baffled osmotic membrane bioreactor-microfiltration hybrid system under continuous operation for simultaneous nutrient removal and mitigation of brine discharge', Bioresource Technology, vol. 240, pp. 50-58.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The present study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor system for wastewater treatment employing baffles in the reactor. Thus, this reactor design enables both aerobic and anoxic processes in an attempt to reduce the process footprint and energy costs associated with continuous aeration. The process performance was evaluated in terms of water flux, salinity build up in the bioreactor, organic and nutrient removal and microbial activity using synthetic reverse osmosis (RO) brine as draw solution (DS). The incorporation of MF membrane was effective in maintaining a reasonable salinity level (612–1434 mg/L) in the reactor which resulted in a much lower flux decline (i.e. 11.48–6.98 LMH) as compared to previous studies. The stable operation of the osmotic membrane bioreactor–forward osmosis (OMBR-FO) process resulted in an effective removal of both organic matter (97.84%) and nutrient (phosphate 87.36% and total nitrogen 94.28%), respectively.
Peng, G, Nakamura, S, Zhu, X, Wu, Q & Wang, H 2017, 'An experimental and numerical study on temperature gradient and thermal stress of CFST truss girders under solar radiation', Computers and Concrete, vol. 20, no. 5, pp. 605-616.
View/Download from: Publisher's site
View description>>
Concrete filled steel tubular (CFST) composite girder is a new type of structures for bridge constructions. The existing design codes cannot be used to predict the thermal stress in the CFST truss girder structures under solar radiation. This study is to develop the temperature gradient curves for predicting thermal stress of the structure based on field and laboratory monitoring data. An in-field testing had been carried out on Ganhaizi Bridge for over two months. Thermal couples were installed at the cross section of the CFST truss girder and the continuous data was collected every 30 minutes. A typical temperature gradient mode was then extracted by comparing temperature distributions at different times. To further verify the temperature gradient mode and investigate the evolution of temperature fields, an outdoor experiment was conducted on a 1:8 scale bridge model, which was installed with both thermal couples and strain gauges. The main factors including solar radiation and ambient temperature on the different positions were studied. Laboratory results were consistent with that from the in-field data and temperature gradient curves were obtained from the in-field and laboratory data. The relationship between the strain difference at top and bottom surfaces of the concrete deck and its corresponding temperature change was also obtained and a method based on curve fitting was proposed to predict the thermal strain under elevated temperature. The thermal stress model for CFST composite girder was derived. By the proposed model, the thermal stress was obtained from the temperature gradient curves. The results using the proposed model were agreed well with that by finite element modelling.
Peng, L, Kassotaki, E, Liu, Y, Sun, J, Dai, X, Pijuan, M, Rodriguez-Roda, I, Buttiglieri, G & Ni, B-J 2017, 'Modelling cometabolic biotransformation of sulfamethoxazole by an enriched ammonia oxidizing bacteria culture', Chemical Engineering Science, vol. 173, pp. 465-473.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Antibiotics such as sulfamethoxazole (SFX) are environmentally hazardous after being released into the aquatic environment and challenges remain in the development of engineered prevention strategies. In this work, a mathematical model was developed to describe and evaluate cometabolic biotransformation of SFX and its transformation products (TPs) in an enriched ammonia oxidizing bacteria (AOB) culture. The growth-linked cometabolic biodegradation by AOB, non-growth transformation by AOB and non-growth transformation by heterotrophs were considered in the model framework. The production of major TPs comprising 4-Nitro-SFX, Desamino-SFX and N4-Acetyl-SFX was also specifically modelled. The validity of the model was demonstrated through testing against literature reported data from extensive batch tests, as well as from long-term experiments in a partial nitritation sequencing batch reactor (SBR) and in a combined SBR + membrane aerated biofilm reactor performing nitrification/denitrification. Modelling results revealed that the removal efficiency of SFX increased with the increase of influent ammonium concentration, whereas the influent organic matter, hydraulic retention time and solid retention time exerted a limited effect on SFX biodegradation with the removal efficiencies varying in a narrow range. The variation of influent SFX concentration had no impact on SFX removal efficiency. The established model framework enables interpretation of a range of experimental observations on SFX biodegradation and helps to identify the optimal conditions for efficient removal.
Peng, L, Liu, Y, Sun, J, Wang, D, Dai, X & Ni, B-J 2017, 'Enhancing immobilization of arsenic in groundwater: A model-based evaluation', Journal of Cleaner Production, vol. 166, pp. 449-457.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The mobilization of arsenic (As) in aquatic environment (groundwater) can cause severe environmental and healthy issues. To develop remediation strategies, we proposed a comprehensive mathematical model to describe the As removal in a arsenite (As (III)) oxidizing and ferrous iron (Fe (II)) oxidizing denitrifying granular biofilm system. In the model framework, the growth-linked microbial oxidation of As (III) and Fe (II) was coupled to chemolithotrophic denitrification of one-step reduction of nitrate to nitrogen gas. Meanwhile, the precipitation of ferric iron (Fe (III)) and adsorption of arsenate (As (V)) onto the biogenic Fe (III) (hydr)oxides were also considered. The model was calibrated by comparing the model predictions against experimental data from batch experiments. The validity of the model was further demonstrated through testing against long-term experimental results from five independent bioreactors with different reactor configurations and operational conditions. Modeling results revealed that the granule size would exert a limited impact on arsenic and iron removal. Nevertheless, their removal efficiencies increased rapidly with the increase of hydraulic retention time (HRT) from 1 h to 12 h, but became independent of HRT as it further increased. The established model framework enables interpretation of a range of experimental observations on As and Fe removal and helps to identify the optimal conditions for enhanced arsenic remediation.
Peng, L, Stewart, MG & Melchers, RE 2017, 'Corrosion and capacity prediction of marine steel infrastructure under a changing environment', Structure and Infrastructure Engineering, vol. 13, no. 8, pp. 988-1001.
View/Download from: Publisher's site
View description>>
The deterioration of marine steel infrastructure caused by corrosion may be influenced by a changing climate and/or pollution level which may lead to its serviceability and structural failure. However, almost all corrosion research until recently assumed time-invariant environmental conditions. A structural reliability analysis is applied here to simulate steel sheet piles in sea water conditions under a changing environment. Corrosion of marine steel infrastructure is modelled as a spatial time-dependent process including sea water temperature and sea level rise due to global warming and dissolved inorganic nitrogen concentration increase caused by pollution. The steel sheet piles are divided vertically into 70 elements to consider the spatial variability of different corrosion zones and sea level rise effects. Two limit states are considered: (i) stress of steel sheet piles reaches their yield stress and (ii) pitting corrosion perforation to provide an alert to repair or maintenance. The results show that ignoring the effects of a changing environment can underestimate structural capacity failure risks, and pollution will have a more significant effect on capacity of steel sheet piles than sea water temperature and sea level rise caused by global warming.
Peng, L, Sun, J, Liu, Y, Dai, X & Ni, B-J 2017, 'Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation', Scientific Reports, vol. 7, no. 1, pp. 1-9.
View/Download from: Publisher's site
View description>>
AbstractSustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N2O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N2O model, which incorporated two N2O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH2OH) oxidation). The two-pathway model was used to describe N2O production from a granule-based partial nitritation (PN) reactor and provide insights into the N2O distribution inside granules. The model was evaluated by comparing simulation results with N2O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N2O dynamics and provided useful information about the shift of N2O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N2O production. The results further revealed a linear relationship between N2O production and ammonia oxidation rate (AOR) (R2 = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N2O production by causing a change in AOR.
Perera, D, Indraratna, B, Leroueil, S, Rujikiatkamjorn, C & Kelly, R 2017, 'Analytical model for vacuum consolidation incorporating soil disturbance caused by mandrel-driven drains', Canadian Geotechnical Journal, vol. 54, no. 4, pp. 547-560.
View/Download from: Publisher's site
View description>>
When vacuum preloading is applied with vertical drains, the rate of consolidation can be increased, and the stability of an embankment is enhanced due to the inward lateral movement. The aim of this study is to develop an analytical solution for vacuum preloading that accurately captures the more realistic variations in compressibility and permeability in actual ground conditions as a result of drain installation. The soil samples were obtained from various locations after drain installation to determine the characteristics of soil surrounding the vertical drain in terms of compressibility and permeability. The main differences between the proposed and conventional models are described by considering the stress history and preloading pressure. The effect of pre-consolidation pressure and the magnitude of applied preloading are examined through the dissipation of average excess pore pressure and associated settlement. The analysis of a selected case history employing the writers’ solution indicates improved accuracy of the predictions in comparison to the field measurements.
Pham, VN, Turner, B, Huang, J & Kelly, R 2017, 'Long-term strength of soil-cement columns in coastal areas', Soils and Foundations, vol. 57, no. 4, pp. 645-654.
View/Download from: Publisher's site
Phan, TN, Van Truong, TT, Ha, NB, Nguyen, PD, Bui, XT, Dang, BT, Doan, VT, Park, J, Guo, W & Ngo, HH 2017, 'High rate nitrogen removal by ANAMMOX internal circulation reactor (IC) for old landfill leachate treatment', Bioresource Technology, vol. 234, pp. 281-288.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This study aimed to evaluate the performance of a high rate nitrogen removal lab-scale ANAMMOX reactor, namely Internal Circulation (IC) reactor, for old landfill leachate treatment. The reactor was operated with pre-treated leachate from a pilot Partial Nitritation Reactor (PNR) using a high nitrogen loading rate ranging from 2 to 10 kg N m−3 d−1. High rate removal of nitrogen (9.52 ± 1.11 kg N m−3 d−1) was observed at an influent nitrogen concentration of 1500 mg N L−1. The specific ANAMMOX activity was found to be 0.598 ± 0.026 gN2-N gVSS−1 d−1. Analysis of ANAMMOX granules suggested that 0.5–1.0 mm size granular sludge was the dominant group. The results of DNA analysis revealed that Candidatus Kueneniastuttgartiensis was the dominant species (37.45%) in the IC reactor, whereas other species like uncultured Bacteroidetes bacterium only constituted 5.37% in the system, but they were still responsible for removing recalcitrant organic matter.
Phuntsho, S, Kim, JE, Hong, S, Ghaffour, N, Leiknes, T, Choi, JY & Shon, HK 2017, 'A closed-loop forward osmosis-nanofiltration hybrid system: Understanding process implications through full-scale simulation', Desalination, vol. 421, pp. 169-178.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. This study presents simulation of a closed-loop forward osmosis (FO)-nanofiltration (NF) hybrid system using fertiliser draw solution (DS) based on thermodynamic mass balance in a full-scale system neglecting the non-idealities such as finite membrane area that may exist in a real process. The simulation shows that the DS input parameters such as initial concentrations and its flow rates cannot be arbitrarily selected for a plant with defined volume output. For a fixed FO-NF plant capacity and feed concentration, the required initial DS flow rate varies inversely with the initial DS concentration or vice-versa. The net DS mass flow rate, a parameter constant for a fixed plant capacity but that increases linearly with the plant capacity and feed concentration, is the most important operational parameter of a closed-loop system. Increasing either of them or both increases the mass flow rate to the system directly affecting the final concentration of the diluted DS with direct energy implications to the NF process. Besides, the initial DS concentration and flow rates are also limited by the optimum recovery rates at which NF process can be operated which otherwise also have direct implications to the NF energy. This simulation also presents quantitative analysis of the reverse diffusion of fertiliser nutrients towards feed brine and the gradual accumulation of feed solutes within the closed system.
Pi, S, Li, A, Wei, W, Feng, L, Zhang, G, Chen, T, Zhou, X, Sun, H & Ma, F 2017, 'Synthesis of a novel magnetic nano-scale biosorbent using extracellular polymeric substances from Klebsiella sp. J1 for tetracycline adsorption', Bioresource Technology, vol. 245, pp. 471-476.
View/Download from: Publisher's site
Plattner, J, Naidu, G, Wintgens, T, Vigneswaran, S & Kazner, C 2017, 'Fluoride removal from groundwater using direct contact membrane distillation (DCMD) and vacuum enhanced DCMD (VEDCMD)', Separation and Purification Technology, vol. 180, pp. 125-132.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Groundwater resources are under growing pressures in water scarce countries. Membrane distillation (MD) is an interesting option for drinking water production from groundwater with elevated salinity and fluoride (F) contamination. A direct contact MD (DCMD) at a moderate feed temperature of 55 °C was able to concentrate a synthetic solution representing F contaminated groundwater. An average initial flux of 13.3 L/m2/h was achieved at 75% water recovery, resulting in only 15–17% flux decline, while producing high quality permeate (96–99% F rejection). Membrane autopsy showed presence of Ca, Na, S and Mg on the used membrane. Particularly, 51–53% F precipitation was estimated in line with the saturation index (SI) model. The used MD membrane with groundwater showed only 10–12% reduction in membrane hydrophobicity, which was largely recovered with simple cleaning. Meanwhile, synthetic groundwater solution spiked with humic substances resulted in brownish deposition on MD membrane, reducing the membrane hydrophobicity significantly by 37–40%. Additionally, DCMD operation with vacuum at the permeate side (vacuum enhanced DCMD; VEDCMD) was beneficial in increasing the permeate flux by 42%. Continuous VEDCMD operation with intermediate membrane cleaning showed positive results in treating F contained groundwater while producing good quality permeate at 67% water recovery.
Pradhan, B, Mohsen Mousavi, S, Golkarian, A, Amir Naghibi, S & Kalantar, B 2017, 'GIS-based Groundwater Spring Potential Mapping Using Data Mining Boosted Regression Tree and Probabilistic Frequency Ratio Models in Iran', AIMS Geosciences, vol. 3, no. 1, pp. 91-115.
View/Download from: Publisher's site
Pradhan, B, Sameen, MI & Kalantar, B 2017, 'Optimized Rule-Based Flood Mapping Technique Using Multitemporal RADARSAT-2 Images in the Tropical Region', IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 10, no. 7, pp. 3190-3199.
View/Download from: Publisher's site
View description>>
Flood is one of the most common natural disasters in Malaysia. Preparing an accurate flood inventory map is the basic step in flood risk management. Flood detection is a complex process because of the limitation of methodological approaches and cloud coverage over tropical areas. An efficient approach is proposed to identify flooded areas using multitemporal RADARSAT-2 imageries. First, multispectral Landsat image was used to extract and subtract permanent water bodies, and this image was later utilized to extract the same information from multitemporal RADARSAT-2 imageries. Next, water bodies during a flood event were extracted from RADARSAT-2 images. Permanent water bodies, shadow, and paddy were detected from synthetic aperture radar (SAR) images by analyzing their temporal backscattering values. During feature extraction, rule-based object-oriented technique was applied to classify both SAR and Landsat images. Image segmentation during object-based analysis was performed to distinguish the boundaries of various dimensions and scales of objects. Moreover, a Taguchibased method was employed to optimize the segmentation parameters. After segmentation, the rules were defined and images were classified to produce an accurate flood inventory map for the 2014 Kelantan flood. A confusion matrix was generated to evaluate the performance of the classification method. The overall accuracy of 86.16% was achieved for RADARSAT-2 using rule-based classification and optimization technique. The resulting flood inventory map using the proposed approach supported the efficiency of the proposed methodology.
Punetha, P, Mohanty, P & Samanta, M 2017, 'Microstructural investigation on mechanical behavior of soil-geosynthetic interface in direct shear test', Geotextiles and Geomembranes, vol. 45, no. 3, pp. 197-210.
View/Download from: Publisher's site
Qian, J, Wang, L, Wu, Y, Bond, PL, Zhang, Y, Chang, X, Deng, B, Wei, L, Li, Q & Wang, Q 2017, 'Free sulfurous acid (FSA) inhibition of biological thiosulfate reduction (BTR) in the sulfur cycle-driven wastewater treatment process', Chemosphere, vol. 176, pp. 212-220.
View/Download from: Publisher's site
View description>>
A sulfur cycle-based bioprocess for co-treatment of wet flue gas desulfurization (WFGD) wastes with freshwater sewage has been developed. In this process the removal of organic carbon is mainly associated with biological sulfate or sulfite reduction. Thiosulfate is a major intermediate during biological sulfate/sulfite reduction, and its reduction to sulfide is the rate-limiting step. In this study, the impacts of saline sulfite (the ionized form: HSO3- + SO32-) and free sulfurous acid (FSA, the unionized form: H2SO3) sourced from WGFD wastes on the biological thiosulfate reduction (BTR) activities were thoroughly investigated. The BTR activity and sulfate/sulfite-reducing bacteria (SRB) populations in the thiosulfate-reducing up-flow anaerobic sludge bed (UASB) reactor decreased when the FSA was added to the UASB influent. Batch experiment results confirmed that FSA, instead of saline sulfite, was the true inhibitor of BTR. And BTR activities dropped by 50% as the FSA concentrations were increased from 8.0 × 10-8 to 2.0 × 10-4 mg H2SO3-S/L. From an engineering perspective, the findings of this study provide some hints on how to ensure effective thiosulfate accumulation in biological sulfate/sulfite reduction for the subsequent denitrification/denitritation. Such manipulation would result in higher nitrogen removal rates in this co-treatment process of WFGD wastes with municipal sewage.
Qian, J, Wei, L, Wu, Y, Wang, Q, Fu, X, Zhang, X, Chang, X, Wang, L & Pei, X 2017, 'A comparative study on denitrifying sludge granulation with different electron donors: Sulfide, thiosulfate and organics', Chemosphere, vol. 186, pp. 322-330.
View/Download from: Publisher's site
View description>>
A comparative study on denitrifying sludge granulation with different electron donors (sulfide, thiosulfate and organics) was carried out. Longer time was spent on sulfide-denitrifying granular sludge (DGS) cultivation (88 days) than thiosulfate- and organics-DGS cultivations (57 days). All the three DGS were characterized in terms of particle size distribution, sludge settling ability (indicated by sludge volume index and settling velocity), permeability (indicated by fractal dimension) and extracellular polymeric substances (EPS, including polysaccharide and protein) secretion. Sludge productions in the three DGS-reactors were also monitored. The key functional microorganisms in three granular reactors were revealed via high through-put pyrosequencing analysis. Batch tests were performed to measure the denitrification activities of each DGS, including both denitratation (NO3- → NO2-) and denitritation (NO2- → N2). We found that thiosulfate-driven denitrifying sludge granulation (TDDSG) should be the most efficient and compact technology for effective BNR in municipal wastewater treatment. The findings of this study suggests the TDDSG could further increase the nitrogen removal potential in an enhanced sulfur cycle-driven bioprocess for co-treatment of wet flue gas desulfurization wastes with fresh sewage depending on three short-cut biological reactions, including: 1) short-cut biological sulfur reduction (SO42-/SO32- → S2O32-); 2) thiosulfate-driven denitritation (S2O32- + NO2- → SO42- + N2↑); and 3) nitritation (NH4+ + O2 → NO2-).
Qian, J, Zhou, J, Wang, L, Wei, L, Li, Q, Wang, D & Wang, Q 2017, 'Direct Cr (VI) bio-reduction with organics as electron donor by anaerobic sludge', Chemical Engineering Journal, vol. 309, pp. 330-338.
View/Download from: Publisher's site
View description>>
Industrial activities produce lots of Cr (VI)-containing wastewater. This study presented a detailed work on direct Cr (VI) bio-reduction (i.e. Cr (VI) is reduced with organics as electron donor directly) by anaerobic sludge through both batch and long-term experiments. Effects of pH and initial Cr (VI) concentrations on direct Cr (VI) bio-reduction activity were evaluated. The highest direct Cr (VI) bio-reduction rate was achieved at pH 8.0 at 104 mg Cr (VI)/g MLVSS/d (MLVSS: mixed liquor volatile suspended solids), corresponding to the highest protein release (124 mg/g MLVSS) and cell viability (71%). In contrast, the direct Cr (VI) bio-reduction rates were 46, 70 and 82 mg Cr (VI)/g MLVSS/d, respectively, at pH 6.0, 7.0 and 9.0. Also, the direct Cr (VI) bio-reduction activity decreased by 74% when initial Cr (VI) concentration increased from 10 mg/L to 50 mg/L. The contribution of chemical adsorption to Cr (VI) removal was found to be negligible, whereas biosorption played a role in Cr (VI) removal although its role was insignificant. Indirect Cr (VI) bio-reduction (i.e. Cr (VI) is chemically reduced by sulfide produced from biological sulfate reduction) rate (990 mg Cr (VI)/g MLVSS/d) was faster than that (210 mg Cr (VI)/g MLVSS/d) of direct Cr (VI) bio-reduction, indicating that indirect Cr (VI) bio-reduction would dominate the Cr (VI) bio-reduction pathway if both Cr (VI) and sulfate were present. The direct Cr (VI) bio-reduction was then successfully demonstrated in an up-flow anaerobic sludge bed (UASB) reactor, where the Cr (VI) was completely removed with a Cr (VI) removal rate of 1.0 mg Cr (VI)/L/h. 454 pyrosequencing results revealed that direct Cr (VI) bio-reduction related genera were Desulfovibrio, Ochrobactrum and Anaerovorax.
Rahman, M, Rasul, M & Hassan, N 2017, 'Study on the Tribological Characteristics of Australian Native First Generation and Second Generation Biodiesel Fuel', Energies, vol. 10, no. 1, pp. 55-55.
View/Download from: Publisher's site
View description>>
Biodiesels are a renewable energy source, and they have the potential to be used as alternatives to diesel fuel. The aim of this study is to investigate the wear and friction characteristics of Australian native first generation and second generation biodiesels using a four-ball tribo tester. The biodiesel was produced through a two-step transesterification process and characterized according to the American Society for Testing and Materials (ASTM) standards. The tribological experiment was carried out at a constant 1800 rpm and different loads and temperatures. In addition, the surface morphology of the ball was tested by scanning electron microscope (SEM)/energy dispersive X-ray spectroscopy (EDX) analysis. The test results indicated that biodiesel fuels have a lower coefficient of frictions (COF) and lower wear scar diameter (WSD) up to 83.50% and 41.28%, respectively, compared to conventional diesel fuel. The worn surface area results showed that biodiesel fuel has a minimum percentage of C and O, except Fe, compared to diesel. In addition, the worn surface area for diesel was found (2.20%-27.92%) to be higher than biodiesel. The findings of this study indicated that both first and second generation biodiesel fuels have better tribological performance than diesel fuel, and between the biodiesel fuels, macadamia biodiesel showed better lubrication performance.
Rahman, MM, Rasul, MG, Hassan, NMS, Azad, AK & Uddin, MN 2017, 'Effect of small proportion of butanol additive on the performance, emission, and combustion of Australian native first- and second-generation biodiesel in a diesel engine', Environmental Science and Pollution Research, vol. 24, no. 28, pp. 22402-22413.
View/Download from: Publisher's site
View description>>
This paper aims to investigate the effect of the addition of 5% alcohol (butanol) with biodiesel-diesel blends on the performance, emissions, and combustion of a naturally aspirated four stroke multi-cylinder diesel engine at different engine speeds (1200 to 2400 rpm) under full load conditions. Three types of local Australian biodiesel, namely macadamia biodiesel (MB), rice bran biodiesel (RB), and waste cooking oil biodiesel (WCB), were used for this study, and the data was compared with results for conventional diesel fuel (B0). Performance results showed that the addition of butanol with diesel-biodiesel blends slightly lowers the engine efficiency. The emission study revealed that the addition of butanol additive with diesel-biodiesel blends lowers the exhaust gas temperature (EGT), carbon monoxide (CO), nitrogen oxide (NOx), and particulate matter (PM) emissions whereas it increases hydrocarbon (HC) emissions compared to B0. The combustion results indicated that in-cylinder pressure (CP) for additive added fuel is higher (0.45-1.49%), while heat release rate (HRR) was lower (2.60-9.10%) than for B0. Also, additive added fuel lowers the ignition delay (ID) by 23-30% than for B0. Finally, it can be recommended that the addition of 5% butanol with Australian biodiesel-diesel blends can significantly lower the NOx and PM emissions.
Rao, P, Chen, Q, Nimbalkar, S & Liu, Y 2017, 'Laboratory study on impulse current characteristics of clay', Environmental Geotechnics, vol. 4, no. 3, pp. 199-208.
View/Download from: Publisher's site
View description>>
Lightning is recognised as one of the most detrimental natural disasters. While numerous research studies were carried out on the lightning impulse characteristics of the grounding system and the critical breakdown characteristics of soil, little attention was paid to the impulse current characteristics of soils when lightning strikes. In this study, the performance of typical soft soil in Shanghai under the action of lightning is analyzed. Different factors, including the impulse current waveforms, the front time and half peak time of impulse current, the quantity of electric charge and absorption of unit heat, have been studied by performing a series of laboratory tests. The test results show that the variation of impulse current due to lightning strike is time dependent. The higher the soil temperature, the larger the peak impulse current produced during lightning strike. The value of the front time decreases exponentially, while the value of the half peak time decreases linearly with the rise of soil temperature. Novel empirical relationships between the impulse current characteristics of soil and soil temperature are proposed, with the aim of providing useful practical references for the design of a grounding system for lightning strikes.
Rao, P-P, Chen, Q, Li, L, Nimbalkar, S & Cui, J 2017, 'Elastoplastic Solution for Spherical Cavity Expansion in Modified Cam-Clay Soil under Drained Condition', International Journal of Geomechanics, vol. 17, no. 8, pp. 06017005-06017005.
View/Download from: Publisher's site
View description>>
© 2017 American Society of Civil Engineers. This paper presents an innovative semianalytical solution for the expansion of a drained spherical cavity with finite initial radius. The widely known modified Cam-clay model is adopted to capture the nonlinear elastoplastic behavior of soil. The rigorous definitions for the mean and deviator stresses are adopted. The problem is then formulated as a set of first-order ordinary differential equations in the Lagrangian form. The radial and tangential stress and specific volume distribution around the cavity are determined. Extensive parametric study is undertaken to investigate effects of the overconsolidation ratio and relative positioning of elastoplastic interface, among others. The applicability of the proposed theoretical approach is demonstrated by a comparison with laboratory test results.
Rasekh, H, Mirzaghorbanali, A, Nemcik, J, Aziz, N & Li, X 2017, 'A New Equation for the Shear Strength of Cable Bolts Incorporating the Energy Balance Theory', Geotechnical and Geological Engineering, vol. 35, no. 4, pp. 1529-1548.
View/Download from: Publisher's site
View description>>
© 2017, Springer International Publishing Switzerland. The application of cable bolts as a secondary support system is an increasing trend in underground coal mines worldwide. The performances of cable bolts have been evaluated under both axial and shear loading conditions. Two methods of testing cables for shear, single and double shear, have been recognised. This paper examines the shear behaviour of a variety of cable bolts under different pre-tension loads by double shear testing. Plain, spiral and the combination of both cable types were used in this study. The initial axial load and the type of cable bolts are the main factors affecting their shear strength. By increasing the axial pre-tension load, the peak shear load occurs at lower shear displacement. The failure angle due to cable bending across the joint at different pre-tension loads varied between 41° and 49°. This demonstrates that the ratio of axial and perpendicular displacements is almost constant and on average the failure occurs at about 45°. A novel analytical model is proposed to evaluate the shear behaviour of pre-tensioned fully grouted cable bolts subjected to double shearing. Energy and Fourier Series methods were incorporated in the model to simulate the shear behaviour of cable bolts. The comparison of the experimental results with the proposed model shows a good agreement.
Rashedul, HK, Kalam, MA, Masjuki, HH, Teoh, YH, How, HG, Monirul, IM & Imdadul, HK 2017, 'Attempts to minimize nitrogen oxide emission from diesel engine by using antioxidant-treated diesel-biodiesel blend', Environmental Science and Pollution Research, vol. 24, no. 10, pp. 9305-9313.
View/Download from: Publisher's site
Reis, R, Duke, M, Merenda, A, Winther-Jensen, B, Puskar, L, Tobin, MJ, Orbell, JD & Dumée, LF 2017, 'Customizing the surface charge of thin-film composite membranes by surface plasma thin film polymerization', Journal of Membrane Science, vol. 537, pp. 1-10.
View/Download from: Publisher's site
View description>>
Solute-surface interactions are critical in membrane science and dominate a number of diffusion and selectivity parameters. In water treatment particularly, the charge on the membrane has been shown to affect ion transport selectivity as well as fouling mechanisms. The development of advanced surface technologies that allow for potential customization of the surface charge for specific applications, without compromising the essential performance of the membrane, is therefore desirable. In this paper, a novel plasma polymerization strategy was applied to commercial reverse osmosis membrane in order to tune the surface charge. Two monomers, maleic anhydride and vinylimidazole, were plasma polymerized onto the membrane resulting in a modification of the surface energy with resultant isoelectric points of approximately pH 3 and pH 7 respectively. This required only a short 5 min plasma polymerization treatment in each case. Thus, in addition to enhancing the water permeation by up to 10%, in comparison to the reference membranes, the overall charge of the membranes was shifted from highly negatively charged upon maleic anhydride polymerization to highly positively charged upon vinylimidazole polymerization. A comprehensive morphological and chemical analysis was performed to correlate the changes to the presence of functional groups and the alteration of the surface texture. Short treatments were found to smooth the surface whilst enriching the surface with either carboxylic or amine/amide groups. This work opens new avenues to engineer advanced membranes with improved performance and selectivity.
Reis, R, Dumée, LF, Merenda, A, Orbell, JD, Schütz, JA & Duke, MC 2017, 'Plasma-induced physicochemical effects on a poly(amide) thin-film composite membrane', Desalination, vol. 403, pp. 3-11.
View/Download from: Publisher's site
View description>>
Helium and water gas plasma were used to modify the surface morphology and chemistry of commercial thin film composite membranes. Such surface treatment is a convenient tool to alter performance of the membranes and subsequently reduce interactions with contaminants in solution. Plasma reactions such as etching and re-deposition resulted in surface functionalization and texturation which were correlated with membrane flux and salt rejection changes. Investigations conducted using atomic force microscopy revealed morphology alterations which were apparent as either smoother surfaces or rougher surfaces. While the smoothing was attributed to a re-deposition of polymer material, which originated most likely from vaporization of surface polymer, the roughening was a result from balanced plasma surface reactions. The beneficial etching can occur under certain conditions when helium is used in conjunction with low excitation power, which resulted in flux enhancements up to 66% (i.e. from 30 L.m− 2.h− 1 to 50 L.m− 2.h− 1) with 98% rejection. The hydrophilicity was dramatically increased from 46.6° to as low as 8.9° after 5 min of helium plasma duration. The impact that plasma treatments have on the nascent structure was discussed in order to highlight its application as a convenient tool to functionalize the surface of thin film composite membranes.
Ren, J, Tijing, LD & Shon, HK 2017, '“Robbing behavior” and re-immobilization of nanoscale zero-valent iron (nZVI) onto electrospun polymeric nanofiber mats for trichloroethylene (TCE) remediation', Separation and Purification Technology, vol. 189, pp. 375-381.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. In this study, we first revealed a “robbing behavior” during the immobilization of nZVI particles onto an electrospun polyacrylic acid (PAA)-polyvinyl alcohol (PVA) nanofiber mat. The robbing behavior can significantly reduce the number of nZVI particles immobilized onto the mat and hence weaken the performance of mitigating contaminated water. To minimize the undesirable effect of robbing behavior, we developed a dipping method that enables exposure of enough free Fe (II) as electron acceptors to the Fe (II)-complexed PAA-PVA mat for the subsequent reduction. The result indicates that the mat with dipping can immobilize more than 1.7 times the weight percentage of nZVI particles for the mat without dipping. Moreover, the dipping method can also re-immobilize or enrich nZVI particles on the mat that has already partially immobilized nZVI particles. The nZVI-immobilized mat dipped once into the FeSO4 solution with a very little concentration (0.32 g/L) had an excellent performance for trichloroethylene (TCE) degradation (more than 92% TCE removed). Here, the developed dipping method shows great potential for nZVI immobilization and groundwater remediation.
Ren, J, Tijing, LD & Shon, HK 2017, 'Effect of polymer ratio on nZVI loading onto Electrospun nanofiber mat for mitigating groundwater contaminants', Advanced Materials - TechConnect Briefs 2017, vol. 2, pp. 265-268.
View description>>
Nanoscale zero-valent iron (nZVI) has been widely used for the reduction of halogenated organics and heavy metals in the groundwater. However, individual nZVI particles are mobile and prone to aggregate, thereby reducing the reaction sites exposed to contaminants. Electrospun polymer nanofiber mat is an ideal carrier to immobilize and distribute nZVI particles after its merits of high specific area, size-controllable and material-compatible properties. In this study, nZVI particles were loaded onto the polyacrylic acid (PAA)-polyvinyl alcohol (PVA) electrospun nanofiber mats with different PAA/PVA ratios. The results indicate that mat with the PAA/PVA ratio of 3:1 loaded the most nZVI particles (∼48 wt%) and had the highest removals to methylene blue at 94% and Cu (II) ions at 84% respectively. The nZVI-loaded electrospun nanofiber mat has promising application for the groundwater contaminants mitigation.
Ren, J, Woo, YC, Yao, M, Tijing, LD & Shon, HK 2017, 'Enhancement of nanoscale zero-valent iron immobilization onto electrospun polymeric nanofiber mats for groundwater remediation', Process Safety and Environmental Protection, vol. 112, no. Part B, pp. 200-208.
View/Download from: Publisher's site
View description>>
© 2017 Institution of Chemical Engineers A new approach that combines nanoscale zero-valent iron (nZVI) with electrospinning technology has been put forward to avoid nZVI agglomeration and a secondary pollution. In this study, to enhance the immobilization of nZVI particles onto the polyacrylic acid (PAA)/polyvinyl alcohol (PVA) electrospun nanofiber mat, mats (M1, M2 and M3) with different PAA/PVA mass ratios (1:1, 2:1 and 3:1) were tested for the immobilization of nZVI particles and their performance of removing contaminants. The results indicate that M3 immobilized the most nZVI particles (48.4 wt% on the mat, ∼2.5 times the figure for previous study) and had the highest removals to methylene blue and Cu(II) ions at 94% and 83.6% respectively, resulting from more free carboxylic groups available on the cross-linked nanofibers as well as a higher porosity into the mat. Therefore, increasing the PAA/PVA ratio is effective to boost the performance of nZVI–PAA/PVA electrospun nanofiber mat, which has a great potential for the application of nZVI-targeted contaminants remediation.
Reyhani, A, McKenzie, TG, Ranji‐Burachaloo, H, Fu, Q & Qiao, GG 2017, 'Fenton‐RAFT Polymerization: An “On‐Demand” Chain‐Growth Method', Chemistry – A European Journal, vol. 23, no. 30, pp. 7221-7226.
View/Download from: Publisher's site
View description>>
AbstractFine control over the architecture and/or microstructure of synthetic polymers is fast becoming a reality owing to the development of efficient and versatile polymerization techniques and conjugation reactions. However, the transition of these syntheses to automated, programmable, and high‐throughput operating systems is a challenging step needed to translate the vast potential of precision polymers into machine‐programmable polymers for biological and functional applications. Chain‐growth polymerizations are particularly appealing for their ability to form structurally and chemically well‐defined macromolecules through living/controlled polymerization techniques. Even using the latest polymerization technologies, the macromolecular engineering of complex functional materials often requires multi‐step syntheses and purification of intermediates, and results in sub‐optimal yields. To develop a proof‐of‐concept of a framework polymerization technique that is readily amenable to automation requires several key characteristics. In this study, a new approach is described that is believed to meet these requirements, thus opening avenues toward automated polymer synthesis.
Riayatsyah, TMI, Ong, HC, Chong, WT, Aditya, L, Hermansyah, H & Mahlia, TMI 2017, 'Life Cycle Cost and Sensitivity Analysis of Reutealis trisperma as Non-Edible Feedstock for Future Biodiesel Production', Energies, vol. 10, no. 7, pp. 877-877.
View/Download from: Publisher's site
View description>>
© 2017 by the authors. The use of non-edible, second-generation feedstocks for the production of biodiesel has been an active area of research, due to its potential in replacing fossil diesel as well as its environmentally friendly qualities. Despite this, more needs to be done to remove the technical barriers associated with biodiesel production and usage, to increase its quality as well as to widen the choice of available feedstocks; so as to avoid over-dependence on limited sources. This paper assesses the feasibility of using a local plant, Reutealis trisperma, whose seeds contain a high percentage of oil of up to 51%, as one of the possible feedstocks. The techno-economic and sensitivity analysis of biodiesel production from Reutealis trisperma oil as well as implementation aspects and environmental effects of the biodiesel plant are discussed. Analysis indicates that the 50 kt Reutealis trisperma biodiesel production plant has a life cycle cost of approximately 710 million, yielding a payback period of 4.34 years. The unit cost of the biodiesel is calculated to be 0.69/L with the feedstock cost accounting for the bulk of the cost. The most important finding from this study is that the biodiesel from Reutealis trisperma oil can compete with fossil diesel, provided that appropriate policies of tax exemptions and subsidies can be put in place. To conclude, further studies on biodiesel production and its limitations are necessary before the use of biodiesel from Reutealis trisperma oil may be used as a fuel source to replace fossil diesel.
Roobavannan, M, Kandasamy, J, Pande, S, Vigneswaran, S & Sivapalan, M 2017, 'Allocating Environmental Water and Impact on Basin Unemployment: Role of A Diversified Economy', Ecological Economics, vol. 136, pp. 178-188.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Water diversion for environmental pu rposes threatens many agricultural communities. This paper focuses on the water-agriculture-environment nexus in the Murrumbidgee River Basin, Australia, and attempts to explain how reduced water allocation to agriculture aimed at protecting the environment in turn impacted the wider economy and the community. Predictably reduced water allocation saw declines in agriculture production and employment. Despite this, paradoxically, the basin unemployment rate declined and basin median household income increased. To understand and interpret this, we first analyze available labour, economic and hydrology data, and then develop a simple dynamic model to interpret the observed pattern of basin employment and unemployment. Data analysis revealed the likely causes behind the paradox as (a) out-migration of people from the basin, and (b) absorption of the labour force in the fast growing non-agricultural sectors of the diversified basin economy. The model simulations reinforced this interpretation. Further model simulations under alternative realities of out-migration and sectoral transformation indicated that basins embedded in faster growing national economies, and are more diversified to begin with, are likely to be more conducive to agriculture sector reform (e.g., reduced water allocation) and environmental regeneration. This is a sobering message for other regions experiencing environmental degradation due to extensive agricultural development.
Ruhul, AM, Kalam, MA, Masjuki, HH, Shahir, SA, Alabdulkarem, A, Teoh, YH, How, HG & Reham, SS 2017, 'Evaluating combustion, performance and emission characteristics of Millettia pinnata and Croton megalocarpus biodiesel blends in a diesel engine', Energy, vol. 141, pp. 2362-2376.
View/Download from: Publisher's site
Ryan, PC & Stewart, MG 2017, 'Cost-benefit analysis of climate change adaptation for power pole networks', Climatic Change, vol. 143, no. 3-4, pp. 519-533.
View/Download from: Publisher's site
View description>>
Power distribution pole networks are vulnerable to a changing climate. Climate change can increase wind speeds, and changes in rainfall and temperature can accelerate timber decay, affecting residual capacity of timber power poles. The present paper utilises advanced stochastic simulation methods to examine climate change impacts, and possible climate change adaptation strategies, for Australian power distribution networks. The assessment framework developed, which is applicable to a wide variety of infrastructure types and research areas, utilises probabilistic methods to investigate the appropriateness of climate adaptation strategies aimed at ameliorating the impact of climate change on critical infrastructure. Measures investigated include alterations to design or maintenance practices through, for example, installation of larger poles, more frequent inspections, or changes to pole replacement criteria. A cost-benefit decision analysis is developed herein using the latest AR5 climate projections, network vulnerability, adaptation measures, and cost and loss data for both direct and indirect costs. The net present value and benefit-to-cost ratio is calculated for different adaptation strategies over the life cycle of the assets up to the year 2090. An adaptation measure that allows for the installation of larger poles but less stringent pole replacement criteria has the highest net benefit—with a mean potential saving of hundreds of millions of dollars.
Saha, N, Rahman, MS, Ahmed, MB, Zhou, JL, Ngo, HH & Guo, W 2017, 'Industrial metal pollution in water and probabilistic assessment of human health risk', Journal of Environmental Management, vol. 185, pp. 70-78.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd Concentration of eight heavy metals in surface and groundwater around Dhaka Export Processing Zone (DEPZ) industrial area were investigated, and the health risk posed to local children and adult residents via ingestion and dermal contact was evaluated using deterministic and probabilistic approaches. Metal concentrations (except Cu, Mn, Ni, and Zn) in Bangshi River water were above the drinking water quality guidelines, while in groundwater were less than the recommended limits. Concentration of metals in surface water decreased as a function of distance. Estimations of non-carcinogenic health risk for surface water revealed that mean hazard index (HI) values of As, Cr, Cu, and Pb for combined pathways (i.e., ingestion and dermal contact) were >1.0 for both age groups. The estimated risk mainly came from the ingestion pathway. However, the HI values for all the examined metals in groundwater were <1.0, indicating no possible human health hazard. Deterministically estimated total cancer risk (TCR) via Bangshi River water exceeded the acceptable limit of 1 × 10−4 for adult and children. Although, probabilistically estimated 95th percentile values of TCR exceeded the benchmark, mean TCR values were less than 1 × 10−4. Simulated results showed that 20.13% and 5.43% values of TCR for surface water were >1 × 10−4 for adult and children, respectively. Deterministic and probabilistic estimations of cancer risk through exposure to groundwater were well below the safety limit. Overall, the population exposed to Bangshi River water remained at carcinogenic and non-carcinogenic health threat and the risk was higher for adults. Sensitivity analysis identified exposure duration (ED) and ingestion rate (IR) of water as the most relevant variables affecting the probabilistic risk estimation model outcome.
Sahebi, S, Phuntsho, S, Tijing, L, Han, G, Han, DS, Abdel-Wahab, A & Shon, HK 2017, 'Thin-film composite membrane on a compacted woven backing fabric for pressure assisted osmosis', Desalination, vol. 406, pp. 98-108.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. The water flux in forward osmosis (FO) process declines substantially when the draw solution (DS) concentration reaches closer to the point of osmotic equilibrium with the feed solution (FS). Using external hydraulic pressure alongside the osmotic driving force in the pressure assisted osmosis (PAO) has been found effective in terms of enhancing water flux and even potentially diluting the DS beyond osmotic equilibrium. The net gain in water flux due to the applied pressure in the PAO process closely depends on the permeability of the FO membrane. The commercial flat sheet cellulose triacetate (CTA) FO membrane has low water permeability and hence the effective gain in water flux in the PAO process is low. In this study, a high performance thin film composite membrane was developed especially for the PAO process through casting polyethersulfone (PES) polymer solution on a compacted woven fabric mesh support followed by interfacial polymerisation for polyamide active layer. This PAO membrane possesses a water flux of 37 L m2h− 1using 0.5 M NaCl as DS and deionised water as the feed at an applied hydraulic pressure of 10 bar. Besides, the membrane was able to endure the external hydraulic pressure required for the PAO process owing to the embedded backing fabric support. While the membranes with low structural parameters are essential for higher water flux, this study shows that for PAO process, polymeric membranes with larger structural parameters may not be suitable for PAO. They generally resulted in compaction and poor mechanical strength to withstand hydraulic pressure.
Saidur, RS, Masjuki, HH, Mahlia, TMI & Nasrudin, AR 2017, 'FACTORS AFFECTING REFRIGERATOR-FREEZERS ENERGY CONSUMPTION', ASEAN Journal on Science and Technology for Development, vol. 19, no. 2, pp. 57-67.
View/Download from: Publisher's site
View description>>
Two frost-free household refrigerator-freezers, one with 492 liter capacity and one with 460 liter capacity were tested in the laboratory to determine the sensitivity of several variables those influence consumption refrigerator-freezers energy consumption greatly. The effects of single variables such as room temperature, thermostat setting positions, and door openings on the energy consumption were investigated. Using Response Surface Methodology (RSM), a mathematical model has been developed to investigate the combined effect of room temperature, thermostat setting positions, and door opening on the energy consumption of refrigerator-freezers. From the mathematical model, it has been observed that room-temperature has the highest effect on the energy consumption followed by the thermostat setting position. The door opening has lowest on the energy consumption. More detailed tests were performed under different room temperature, thermostat setting positions, and door opening conditions and presented in this paper.
Saller, BD, Sha, G, Yang, LM, Liu, F, Ringer, SP & Schoenung, JM 2017, 'Iron in solution with aluminum matrix after non-equilibrium processing: an atom probe tomography study', Philosophical Magazine Letters, vol. 97, no. 3, pp. 118-124.
View/Download from: Publisher's site
Sameen, M & Pradhan, B 2017, 'Severity Prediction of Traffic Accidents with Recurrent Neural Networks', Applied Sciences, vol. 7, no. 6, pp. 476-476.
View/Download from: Publisher's site
View description>>
In this paper, a deep learning model using a Recurrent Neural Network (RNN) was developed and employed to predict the injury severity of traffic accidents based on 1130 accident records that have occurred on the North-South Expressway (NSE), Malaysia over a six-year period from 2009 to 2015. Compared to traditional Neural Networks (NNs), the RNN method is more effective for sequential data, and is expected to capture temporal correlations among the traffic accident records. Several network architectures and configurations were tested through a systematic grid search to determine an optimal network for predicting the injury severity of traffic accidents. The selected network architecture comprised of a Long-Short Term Memory (LSTM) layer, two fully-connected (dense) layers and a Softmax layer. Next, to avoid over-fitting, the dropout technique with a probability of 0.3 was applied. Further, the network was trained with a Stochastic Gradient Descent (SGD) algorithm (learning rate = 0.01) in the Tensorflow framework. A sensitivity analysis of the RNN model was further conducted to determine these factors’ impact on injury severity outcomes. Also, the proposed RNN model was compared with Multilayer Perceptron (MLP) and Bayesian Logistic Regression (BLR) models to understand its advantages and limitations. The results of the comparative analyses showed that the RNN model outperformed the MLP and BLR models. The validation accuracy of the RNN model was 71.77%, whereas the MLP and BLR models achieved 65.48% and 58.30% respectively. The findings of this study indicate that the RNN model, in deep learning frameworks, can be a promising tool for predicting the injury severity of traffic accidents.
Sameen, MI & Pradhan, B 2017, 'A Simplified Semi-Automatic Technique for Highway Extraction from High-Resolution Airborne LiDAR Data and Orthophotos', Journal of the Indian Society of Remote Sensing, vol. 45, no. 3, pp. 395-405.
View/Download from: Publisher's site
View description>>
Information on highways is an essential input for various geospatial applications, including car navigation, forensic analysis on highway geometries, and intelligent transportation systems. Semi-automatic and automatic extractions of highways are critical for the regular updating of municipal databases and for highway maintenance. This study presents a semi-automatic data processing approach for extracting highways from high-resolution airborne LiDAR height information and aerial orthophotos. The method was developed based on two data sets. Experimental results for the first testing site showed that the accuracy of the proposed method for highway extraction was 74.50 % for completeness and 73.13 % for correctness. Meanwhile, the completeness and correctness for the second testing site were 71.20 and 70.72 %, respectively. The proposed method was compared with an object-based approach on a different data set. The accuracy for highway extraction of the object-based approach was 64.29 % for completeness and 63.11 % for correctness, whereas that of the proposed method was 67.14 % for completeness and 65.08 % for correctness. This research aims to promote semi-automatic highway extraction from LiDAR data and orthophotos by proposing a new approach and a multistep post-processing technique. The proposed method provides an accurate final output that is valuable for a wide range of geospatial applications.
Sameen, MI & Pradhan, B 2017, 'A Two-Stage Optimization Strategy for Fuzzy Object-Based Analysis Using Airborne LiDAR and High-Resolution Orthophotos for Urban Road Extraction', Journal of Sensors, vol. 2017, pp. 1-17.
View/Download from: Publisher's site
View description>>
In the last decade, object-based image analysis (OBIA) has been extensively recognized as an effective classification method for very high spatial resolution images or integrated data from different sources. In this study, a two-stage optimization strategy for fuzzy object-based analysis using airborne LiDAR was proposed for urban road extraction. The method optimizes the two basic steps of OBIA, namely, segmentation and classification, to realize accurate land cover mapping and urban road extraction. This objective was achieved by selecting the optimum scale parameter to maximize class separability and the optimum shape and compactness parameters to optimize the final image segments. Class separability was maximized using the Bhattacharyya distance algorithm, whereas image segmentation was optimized using the Taguchi method. The proposed fuzzy rules were created based on integrated data and expert knowledge. Spectral, spatial, and texture features were used under fuzzy rules by implementing the particle swarm optimization technique. The proposed fuzzy rules were easy to implement and were transferable to other areas. An overall accuracy of 82% and a kappa index of agreement (KIA) of 0.79 were achieved on the studied area when results were compared with reference objects created via manual digitization in a geographic information system. The accuracy of road extraction using the developed fuzzy rules was 0.76 (producer), 0.85 (user), and 0.72 (KIA). Meanwhile, overall accuracy was decreased by approximately 6% when the rules were applied on a test site. A KIA of 0.70 was achieved on the test site using the same rules without any changes. The accuracy of the extracted urban roads from the test site was 0.72 (KIA), which decreased to approximately 0.16. Spatial information (i.e., elongation) and intensity from LiDAR were the most interesting properties for urban road extraction. The proposed method can be applied to a wide range of real applicatio...
Sameen, MI & Pradhan, B 2017, 'Assessment of the effects of expressway geometric design features on the frequency of accident crash rates using high-resolution laser scanning data and GIS', Geomatics, Natural Hazards and Risk, vol. 8, no. 2, pp. 733-747.
View/Download from: Publisher's site
Sameen, MI, Pradhan, B, Shafri, HZM, Mezaal, MR & Hamid, HB 2017, 'Integration of Ant Colony Optimization and Object-Based Analysis for LiDAR Data Classification', IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, vol. 10, no. 5, pp. 2055-2066.
View/Download from: Publisher's site
View description>>
© 2017 IEEE. Light detection and ranging (LiDAR) data classification provides useful thematic maps for numerous geospatial applications. Several methods and algorithms have been proposed recently for LiDAR data classification. Most studies focused on object-based analysis because of its advantages over per-pixel-based methods. However, several issues, such as parameter optimization, attribute selection, and development of transferable rulesets, remain challenging in this topic. This study contributes to LiDAR data classification by developing an approach that integrates ant colony optimization (ACO) and rule-based classification. First, LiDAR-derived digital elevation and digital surface models were integrated with high-resolution orthophotos. Second, the processed raster was segmented with the multiresolution segmentation method. Subsequently, the parameters were optimized with a supervised technique based on fuzzy analysis. A total of 20 attributes were selected based on general knowledge on the study area and LiDAR data; the best subset containing 12 attributes was then selected via ACO. These attributes were utilized to develop rulesets through the use of a decision tree algorithm, and a thematic map was generated for the study area. Results revealed the robustness of the proposed method, which has an overall accuracy of ∼95% and a kappa coefficient of 0.94. The rule-based approach with all attributes and the k nearest neighbor (KNN) classification method were applied to validate the results of the proposed method. The overall accuracy of the rule-based method with all attributes was ∼88% (kappa = 0.82), whereas the KNN method had an overall accuracy of <70% and produced a poor thematic map. The selection of the ACO algorithm was justified through a comparison with three well-known feature selection methods. On the other hand, the transferability of the developed rules was evaluated by using a second LiDAR dataset at another study area. The overall ...
Sebayang, A, Hassan, M, Ong, H, Dharma, S, Silitonga, A, Kusumo, F, Mahlia, T & Bahar, A 2017, 'Optimization of Reducing Sugar Production from Manihot glaziovii Starch Using Response Surface Methodology', Energies, vol. 10, no. 1, pp. 35-35.
View/Download from: Publisher's site
View description>>
Bioethanol is known as a viable alternative fuel to solve both energy and environmental crises. This study used response surface methodology based on the Box-Behnken experimental design to obtain the optimum conditions for and quality of bioethanol production. Enzymatic hydrolysis optimization was performed with selected hydrolysis parameters, including substrate loading, stroke speed, α-amylase concentration and amyloglucosidase concentration. From the experiment, the resulting optimum conditions are 23.88% (w/v) substrate loading, 109.43 U/g α-amylase concentration, 65.44 U/mL amyloglucosidase concentration and 74.87 rpm stroke speed, which yielded 196.23 g/L reducing sugar. The fermentation process was also carried out, with a production value of 0.45 g ethanol/g reducing sugar, which is equivalent to 88.61% of ethanol yield after fermentation by using Saccharomyces cerevisiae (S. cerevisiae). The physical and chemical properties of the produced ethanol are within the specifications of the ASTM D4806 standard. The good quality of ethanol produced from this study indicates that Manihot glaziovii (M. glaziovii) has great potential as bioethanol feedstock.
Sebayang, AH, Hasan, MH, Chyuan, OH, Dharma, S, Bahar, AH, Silitonga, AS & Kusumo, F 2017, 'Enzymatic hydrolysis using ultrasound for bioethanol production from durian (durio zibethinus) seeds as potential bio fuel', Chemical Engineering Transactions, vol. 56, pp. 553-558.
View/Download from: Publisher's site
View description>>
The appealing second generation bioethanol production brings a good promise to achieve a fuel production that is renewable and sustainable; this makes durian (Durio zibethinus) seed interesting to take advantage of, especially for a tropical country like Malaysia. This paper aims to produce bioethanol from durian seed by utilizing ultrasound technique in its enzymatic hydrolysis process. 9 % (w/v) pre-Treated durian seed was brought into the ultrasound-Assisted glass reactor to begin the liquefaction and saccharification processes. Bacillus licheniformis Type XII-A was employed, and ultrasound at 50% amplitude for 60 min was set for liquefaction process; while amyloglucosidase from Aspergillus niger was used, and ultrasound at 40% amplitude for 120 min was run for saccharification process. The sum of both processes in hydrolysis yielded 41.07 g/L of reducing sugar, which was immediately brought to fermentation stage. Saccharomyces cerevisiae was employed for fermentation and resulted 18.48 g/L (0.44 g ethanol/g glucose), which is equivalent to 86.27 % of theoretical ethanol yield (0.51 g ethanol/g glucose) after 84 h of fermentation at 37 °C with 150 rpm incubator shaker. The ethanol purity was improved in the next stage, distillation. Using zeolite as adsorbent, ethanol with purity of 95.7% (v/v) was produced. From the acquired results, durian seed shows a justifiably potential as a second generation bioethanol feedstock. To further improve its potential, studies of optimization using this feedstock is highly encouraged.
Sebayang, AH, Masjuki, HH, Ong, HC, Dharma, S, Silitonga, AS, Kusumo, F & Milano, J 2017, 'Optimization of bioethanol production from sorghum grains using artificial neural networks integrated with ant colony', Industrial Crops and Products, vol. 97, pp. 146-155.
View/Download from: Publisher's site
View description>>
In this study, an artificial neural networks (ANN) model is developed to investigate the relationship between bioethanol production and the operating parameters of enzymatic hydrolysis and fermentation processes. The operating parameters of the hydrolysis process which influence the reducing sugar concentration are the substrate loading, α-amylase concentration, amyloglucosidase concentration and strokes speed. The operating parameters of the fermentation process which influence the ethanol concentration are the yeast concentration, reaction temperature and agitation speed. The desirability function of the model is integrated with ant colony optimization (ACO) in order to determine the optimum operating parameters which will maximize reducing sugar and ethanol concentrations. The optimum substrate loading, α-amylase concentration, amyloglucosidase concentration and strokes speed is determined to be 20% (w/v), 109.5 U/g, 36 U/mL and 50 spm, respectively. The reducing sugar obtained at these optimum conditions is 175.94 g/L, which is close to the average value from experiments (174.29 g/L). The optimum yeast concentration, reaction temperature and agitation speed is found to be 1.3 g/L, 35.6 °C and 181 rpm, respectively. The ethanol concentration obtained from the fermentation of sorghum starch by Saccharomyces cerevisiae yeast at these optimum conditions is 82.11 g/L, which is in good agreement with the average value from experiments (81.52 g/L). Based on the results, it can be concluded that the model developed in this study model is an effective method to optimize bioethanol production, and it reduces the cost, time and effort associated with experimental techniques.
Sebayang, AH, Masjuki, HH, Ong, HC, Dharma, S, Silitonga, AS, Kusumo, F & Milano, J 2017, 'Prediction of engine performance and emissions with Manihot glaziovii bioethanol − Gasoline blended using extreme learning machine', Fuel, vol. 210, pp. 914-921.
View/Download from: Publisher's site
View description>>
Bioethanol can potentially replace gasoline because of its lower exhaust emissions. The purpose of this study was to investigate the engine performance and exhaust emissions of Manihot glaziovii bioethanol–gasoline blends at different blend ratios (5%, 10%, 15%, and 20%). Tests were performed on a single-cylinder, four-stroke spark-ignition engine with engine speed was varied from 1600 to 3400 rpm, and the properties of the Manihot glaziovii bioethanol–gasoline blends were measured and analysed. The vapour pressure increased for fuel blends with low concentrations of bioethanol due to the oxygen within the bioethanol molecules and the contribution of the flame speed which can enhance the combustion and improved the engine efficiency. In addition, the engine torque, brake power, and brake-specific fuel consumption (BSFC) were measured, as well as the carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide emissions. For a fuel blend containing 20% bioethanol at an engine speed of 3200 rpm, the BSFC decreased, with maximum values of 270.7 g/kWh. The CO and HC emissions were lower for the Manihot glaziovii bioethanol–gasoline blends. In addition, an extreme learning machine (ELM) model was developed for application in the automotive and industrial sectors. This tool reduces the cost, time, and effort associated with experimental data. The blend ratio of the bioethanol–gasoline blends and the engine speed were used as the input data of the model, and the engine performance and exhaust emissions parameters were used as the output data. The coefficient of determination (R2) was within a range of 0.980–1.000, and the mean absolute percentage error was within a range of 0.411%−2.782% for all the parameters. The results indicate that the ELM model is capable of predicting the engine performance and exhaust emissions of bioethanol–gasoline fuel blends.
Semblante, GU, Hai, FI, McDonald, J, Khan, SJ, Nelson, M, Lee, D-J, Price, WE & Nghiem, LD 2017, 'Fate of trace organic contaminants in oxic-settling-anoxic (OSA) process applied for biosolids reduction during wastewater treatment', Bioresource Technology, vol. 240, pp. 181-191.
View/Download from: Publisher's site
View description>>
This study investigated the fate of trace organic contaminants (TrOCs) in an oxic-settling-anoxic (OSA) process consisting of a sequencing batch reactor (SBR) with external aerobic/anoxic and anoxic reactors. OSA did not negatively affect TrOC removal of the SBR. Generally, low TrOC removal was observed under anoxic and low substrate conditions, implicating the role of co-metabolism in TrOC biodegradation. Several TrOCs that were recalcitrant in the SBR (e.g., benzotriazole) were biodegraded in the external aerobic/anoxic reactor. Some hydrophobic TrOCs (e.g., triclosan) were desorbed in the anoxic reactor possibly due to loss of sorption sites through volatile solids destruction. In OSA, the sludge was discharged from the aerobic/anoxic reactor which contained lower concentration of TrOCs (e.g., triclosan and triclocarban) than that of the control aerobic digester, suggesting that OSA can also help to reduce TrOC concentration in residual biosolids.
Semblante, GU, Phan, HV, Hai, FI, Xu, Z-Q, Price, WE & Nghiem, LD 2017, 'The role of microbial diversity and composition in minimizing sludge production in the oxic-settling-anoxic process', Science of The Total Environment, vol. 607-608, pp. 558-567.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The oxic-settling-anoxic (OSA) process, which involves an aerobic tank attached to oxygen- and substrate-deficient external anoxic reactors, minimizes sludge production in biological wastewater treatment. In this study, the microbial community structure of OSA was determined. Principal coordinate analysis showed that among the three operational factors, i.e., (i) redox condition, (ii) external reactor sludge retention time (SRText), and (iii) sludge interchange between aerobic and anoxic reactors, redox condition had the greatest impact on microbial diversity. Generally, reactors with lower oxidation-reduction potential had higher microbial diversity. The main aerobic sequencing batch reactor of OSA (SBROSA) that interchanged sludge with an external anoxic reactor had greater microbial diversity than SBRcontrol which did not have sludge interchange. SBROSA sustained high abundance of the slow-growing nitrifying bacteria (e.g., Nitrospirales and Nitrosomondales) and consequently exhibited reduced sludge yield. Specific groups of bacteria facilitated sludge autolysis in the external reactors. Hydrolyzing (e.g., Bacteroidetes and Chloroflexi) and fermentative (e.g., Firmicutes) bacteria, which can break down cellular matter, proliferated in both the external aerobic/anoxic and anoxic reactors. Sludge autolysis in the anoxic reactor was enhanced with the increase of predatory bacteria (e.g., order Myxobacteriales and genus Bdellovibrio) that can contribute to biomass decay. Furthermore, β- and γ-Proteobacteria were identified as the bacterial phyla that primarily underwent decay in the external reactors.
Shakor, P, Sanjayan, J, Nazari, A & Nejadi, S 2017, 'Modified 3D printed powder to cement-based material and mechanical properties of cement scaffold used in 3D printing', Construction and Building Materials, vol. 138, pp. 398-409.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Additive manufacturing is a common technique used to produce 3D printed structures. These techniques have been used as precise application geometry in different fields such as architecture and medicine, and the food, mechanics and chemical industries. However, in most cases only a limited amount of powder has been used to fabricate scaffold (structure). In this study, a unique mix of cements (calcium aluminate cement passed through a 150 μm sieve and ordinary Portland cement) was developed for Z-Corporation's three-dimensional printing (3DP) process. This cement mix was blended and the resulting composite powders were printed with a water-based binder using a Z-Corporation 3D printer. Moreover, some samples were added lithium carbonate to reduce the setting time for the cement mixture. The aims of the study were to firstly, find the proper cementitious powder close to the targeted powder (Z-powder); and secondly, evaluate the mechanical properties of this material. Cubic specimens of two different batches with varying saturation levels were cast and cured in various scenarios to enhance the best mechanical properties. The samples were characterised by porosity analyses, compression tests, Olympus BX61 Microscope imaging, 3D profiling Veeco (Dektak) and the Scanning Electronic Microscope (SEM). The maximum compressive strength of the cubic specimens for cementitious 3DP was 8.26 MPa at the saturation level of 170% for both the shell and core. The minimum porosity obtained was 49.28% at the saturation level of 170% and 340% for the shell and the core, respectively.
Shanmuganathan, S, Loganathan, P, Kazner, C, Johir, MAH & Vigneswaran, S 2017, 'Submerged membrane filtration adsorption hybrid system for the removal of organic micropollutants from a water reclamation plant reverse osmosis concentrate', DESALINATION, vol. 401, pp. 134-141.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Reverse osmosis (RO) is a widespread water treatment process utilised in water reuse applications. However, the improper discharge of RO concentrate (ROC) containing organic micropollutants such as pharmaceuticals into the environment may cause potential health risks to non-target species and particularly those in aquatic environments. A study was conducted using a submerged membrane-filtration/granular activated carbon (GAC) adsorption hybrid system to remove organic micropollutants from a water treatment plant ROC by initially adding 10 g GAC /L of membrane reactor volume with 10% daily GAC replacement. The percentage of dissolved organic carbon removal varied from 60% to 80% over an operation lasting 10 days. Removal of organic micropollutants was almost complete for virtually all compounds. Of the 19 micropollutants tested, only two remained (the less hydrophobic DEET 27 ng/L and the hydrophilic sulfamethoxazole 35 ng/L) below 80% removal on day 1, while five of the most hydrophobic micropollutants were detectable in very small concentrations (< 5–10 ng/L) with > 89%–> 99% being removed. High percentages of micropollutants were removed probably because of their high hydrophobicity or they had positive or neutral charges and therefore they were electrostatically adsorbed to the negatively charged GAC.
Shekarchian, M, Moghavvemi, M, Zarifi, F, Moghavvemi, S, Motasemi, F & Mahlia, TMI 2017, 'Impact of infrastructural policies to reduce travel time expenditure of car users with significant reductions in energy consumption', Renewable and Sustainable Energy Reviews, vol. 77, pp. 327-335.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The increasing number of vehicles and drivers have led to a marked increase in travel time expenditure (TTE), congestion, demand for fossil fuels, and adverse environmental impacts. Improving energy efficiency in the transportation sector, public awareness of the behavior of the people vis-à-vis energy efficiency, implementing policies that encourage other modes of transportation (e.g., public transit, ride-sharing, bicycles, and walking, etc.) that decrease vehicle dependency are some effective approaches that mitigate the aforementioned negative effects, which will lead to significant reductions in the total energy consumption. This article investigates the effect of governmental policies on vehicle dependency reduction and the decrease of TTE by vehicle owners, and propose a novel method to calculate the current and future TTEs by individuals. The effect of demographic variables and the region on vehicle dependency and TTE for students of three of the most populated universities in Malaysia (University of Malaya, University Putra Malaysia, and University Technology Malaysia) were investigated as well. The peoples’ expectations from individual modes of transportation such as cycling and walking were also analyzed. The results showed that all demographic factors, except nationality, affect the levels of vehicle ownership, while income levels and nationality affects TTE by personal vehicles. The results show that the average TTE can be reduced by 89% if the recommended infrastructure (e.g., increase bus routes, train routes, train services, frequencies of buses and train, and facilities for cyclists, etc.) is provided. These outcomes can assist policy makers to efficiently manage transportation budgets, and would also help people decrease vehicle usage, which will subsequently decrease their corresponding TTE and fuel consumption.
Shi, W, Chen, Q, Nimbalkar, S & Liu, W 2017, 'A new mixing technique for solidifier and dredged fill in coastal area', Marine Georesources & Geotechnology, vol. 35, no. 1, pp. 52-61.
View/Download from: Publisher's site
View description>>
2016 Copyright © Taylor & Francis Group, LLCOne of the major drawbacks of the conventional method of land reclamation, which involves mixing cement with the dredged soils at the disposal site, is the high cost associated with its manufacturing and transportation. In this study, a new solidified dredged fill (SDF) technique and a new additive are proposed and their practical applications are discussed. Unlike the conventional approach, the dredged marine soils were mixed with the solidifiers using a newly designed mixing technique prior to its transport to site, which would significantly reduce the cost of site machinery and effectively reclaim land with adequate engineering properties necessary for the construction of infrastructure. To evaluate the performance of the reclaimed land using the proposed technique, a series of laboratory and field tests (namely, static and dynamic cone penetration tests, and plate load tests) were conducted on grounds filled with and without solidified dredged marine soils, respectively. The results showed that the engineering behavior of the reclaimed land with dredged marine soils using SDF technique had significantly improved. The SDF technique combined with the newly designed mixing system improved the performance of ground and has thus proved to be both cost-effective and safe.
Shirvani, Z, Abdi, O, Buchroithner, MF & Pradhan, B 2017, 'Analysing Spatial and Statistical Dependencies of Deforestation Affected by Residential Growth: Gorganrood Basin, Northeast Iran', Land Degradation & Development, vol. 28, no. 7, pp. 2176-2190.
View/Download from: Publisher's site
View description>>
AbstractThis study aimed to examine deforestation and residential growth trends and their spatial dependencies from 1972 to 2010 in Northeast of Iran. First, change rates of forests and residential areas were mapped using Landsat satellite images in 1972–1987, 1987–2000 and 2000–2010. Then, the forest change patterns were interpreted using univariate local Moran's I (local univariate spatial autocorrelation), and the spatial autocorrelation between deforestation and residential growth was tested through bivariate local Moran's I (bivariate local spatial autocorrelation). Furthermore, the spatial relationships between deforestation and residential growth rates were quantified by ordinary least squares, spatial lag (SL) and geographically weighted regression. Results indicated that approximately 25% of forests have been converted to other land‐use types in the span of 38 years, since 1972. Local univariate spatial autocorrelation maps showed that significant values of high–high cluster scattered in all locations in the first span, in the east and south aspects in the second duration, and in the eastern part in the third span. Bivariate local spatial autocorrelation indicated a meaningful Moran's I values of −0·12, −0·26 and −0·20 between deforestation and residential growth, chronologically. Analyses of spatial regression models showed that geographically weighted regression performed better than SL and ordinary least squares in the first (R2 = 0·315, AIC = 6,160) and third periods (R2 = 0·27, AIC = 6,351), whereas, the validity of SL was the highest in the second period (R2 = 0·36, AIC = 6,288). However, the overall trends of deforestation and residential growth have decreased, but the rate of deforestation induced by residential growth is still significant. Spatial exploration of...
Shon, HK 2017, 'Editorial - Special issue on the 9th International Conference on Challenges in Environmental Science and Engineering (CESE-2016), 6–10 November 2016, Kaohsiung, Taiwan', DESALINATION AND WATER TREATMENT, vol. 96, pp. 1-2.
View/Download from: Publisher's site
Shon, HK, Jegatheesan, V, Shu, L & Phuntsho, S 2017, 'Challenges in Environmental Science and Engineering, CESE–2016', Process Safety and Environmental Protection, vol. 112, no. PART B, pp. 199-199.
View/Download from: Publisher's site
Shrestha, A, Naidu, G, Johir, MAH, Kandasamy, J & Vigneswaran, S 2017, 'Performance of flocculation titanium salts for seawater reverse osmosis pretreatment', DESALINATION AND WATER TREATMENT, vol. 98, pp. 92-97.
View/Download from: Publisher's site
View description>>
© 2017 Desalination Publications. All rights reserved. This study evaluated the performance of titanium tetrachloride (TiCl4) and titanium sulphate (Ti(SO4)2) as coagulants to remove organic matter and solids from actual seawater. The coagulant performances were evaluated at different doses in terms of turbidity, dissolved organic carbon (DOC), humics (UV254), zeta potential and pH of the solution. The performance of Ti-salts were compared to ferric chloride (FeCl3), a commonly used coagulant. The results showed that at pH of 8.0 (closely similar to seawater pH), TiCl4 showed relatively better performance over FeCl3 and Ti(SO4)2 for the same coagulant dose of 20 mg/L. TiCl4 achieved a 70% DOC and UV254 removal. This was approximately two times higher than achieved by FeCl3 and Ti(SO4)2. Based on a floc zeta potential evaluation, the difference in performance of the coagulants were attributed to the coagulation mechanism. The coagulation mechanisms of Ti-salts were mainly charge neutralization while FeCl3was adsorption mechanism.
Shuhimi, FF, Abdollah, MFB, Kalam, MA, Masjuki, HH, Mustafa, A, Mat Kamal, SE & Amiruddin, H 2017, 'Effect of operating parameters and chemical treatment on the tribological performance of natural fiber composites: A review', Particulate Science and Technology, vol. 35, no. 5, pp. 512-524.
View/Download from: Publisher's site
Silitonga, AS, Hassan, MH, Ong, HC & Kusumo, F 2017, 'Analysis of the performance, emission and combustion characteristics of a turbocharged diesel engine fuelled with Jatropha curcas biodiesel-diesel blends using kernel-based extreme learning machine', Environmental Science and Pollution Research, vol. 24, no. 32, pp. 25383-25405.
View/Download from: Publisher's site
View description>>
The purpose of this study is to investigate the performance, emission and combustion characteristics of a four-cylinder common-rail turbocharged diesel engine fuelled with Jatropha curcas biodiesel-diesel blends. A kernel-based extreme learning machine (KELM) model is developed in this study using MATLAB software in order to predict the performance, combustion and emission characteristics of the engine. To acquire the data for training and testing the KELM model, the engine speed was selected as the input parameter, whereas the performance, exhaust emissions and combustion characteristics were chosen as the output parameters of the KELM model. The performance, emissions and combustion characteristics predicted by the KELM model were validated by comparing the predicted data with the experimental data. The results show that the coefficient of determination of the parameters is within a range of 0.9805-0.9991 for both the KELM model and the experimental data. The mean absolute percentage error is within a range of 0.1259-2.3838. This study shows that KELM modelling is a useful technique in biodiesel production since it facilitates scientists and researchers to predict the performance, exhaust emissions and combustion characteristics of internal combustion engines with high accuracy.
Silitonga, AS, Mahlia, TMI, Ong, HC, Riayatsyah, TMI, Kusumo, F, Ibrahim, H, Dharma, S & Gumilang, D 2017, 'A comparative study of biodiesel production methods for Reutealis trisperma biodiesel', Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 39, no. 20, pp. 2006-2014.
View/Download from: Publisher's site
View description>>
© 2017 Taylor & Francis Group, LLC. In this study, three types of biodiesel production methods are compared in order to maximize Reutealis trisperma biodiesel yields and it is found that the best method is esterification-neutralization-transesterification. The optimum methanol to oil molar ratio, catalyst concentration, reaction temperature, and reaction time are also determined from laboratory experiments and modeling using response surface methodology. There is excellent agreement between the predicted and experimental Reutealis trisperma biodiesel yields under optimum process conditions, with a value of 99.23 and 98.72%, respectively. The physicochemical properties of the Reutealis trisperma biodiesel also fulfill the fuel specifications of the ASTM D6751 standard.
Silitonga, AS, Masjuki, HH, Ong, HC, Mahlia, TMI & Kusumo, F 2017, 'Optimization of extraction of lipid from Isochrysis galbana microalgae species for biodiesel synthesis', Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, vol. 39, no. 11, pp. 1167-1175.
View/Download from: Publisher's site
View description>>
© 2017 Taylor & Francis Group, LLC. Microalgae are promising alternative plant sources for biodiesel production because of the significant increase in lipid yield through heterotrophic cultivation and genetic engineering approaches. This study aims to evaluate the extraction and conversion of lipids from Isochrysis galbana. Response surface methodology (RSM) was used to optimize lipid extraction and thereby obtain high yields from the four microalgae species. The optimal lipid yields for Isochrysis galbana is 8.41 wt%. Moreover, the dominant lipid composition found from Isochrysis galbana extractions was palmitic acid (C16:0) at 22.3%. The high saturated acid of Isochrysis galbana contributed to the improved biodiesel properties because biodiesel quality is influenced by the lipid composition of microalgae species. The study employed the two-step esterification–transesterification process to convert the microalgae oil into biodiesel, glycerol, and water. The FAME content is 99.7% under the methanol to oil molar mass of 12:1, 1 wt%, 65°C, and 800 rpm. Furthermore, the main biodiesel properties, such as viscosity, higher heating value, and iodine value, were measured according to ASTM D6751 and EN 14124. Results show that microalgae oil can potentially be used as biofuel in future applications.
Song, K, Xie, G-J, Qian, J, Bond, PL, Wang, D, Zhou, B, Liu, Y & Wang, Q 2017, 'Improved degradation of anaerobically digested sludge during post aerobic digestion using ultrasonic pretreatment', Environmental Science: Water Research & Technology, vol. 3, no. 5, pp. 857-864.
View/Download from: Publisher's site
View description>>
We propose that ultrasonic pretreatment could significantly improve the degradation of anaerobically digested sludge with economic favorability in post aerobic digestion.
Sounthararajah, DP, Loganathan, P, Kandasamy, J & Vigneswaran, S 2017, 'Removing heavy metals using permeable pavement system with a titanate nano-fibrous adsorbent column as a post treatment', Chemosphere, vol. 168, pp. 467-473.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd Permeable pavement systems (PPS) are a widely-used treatment measure in sustainable stormwater management and groundwater recharge. However, PPS are not very efficient in removing heavy metals from stormwater. A pilot scale study using zeolite or basalt as bed material in PPS removed 41–72%, 67–74%, 38–43%, 61–72%, 63–73% of Cd, Cu, Ni, Pb, and Zn, respectively, from synthetic stormwater (pH 6.5; Cd, Cu, Ni, Pb, and Zn concentrations of 0.04, 0.6, 0.06, 1.0, and 2.0 mg L−1, respectively) over a period of 80 h. The total volume of stormwater that passed through the PPS was equivalent to runoff in 10 years of rainfall in Sydney, Australia. The concentrations of metals in the PPS effluent failed fresh and marine water quality trigger values recommended in the Australian and New Zealand guidelines. An addition of a post-treatment of a horizontal filter column containing a titanate nano-fibrous (TNF) material with a weight < 1% of zeolite weight and mixed in with granular activated carbon (GAC) at a GAC:TNF weight ratio of 25:1 removed 77% of Ni and 99–100% of all the other metals. The effluent easily met the required standards of marine waters and just met those concerning fresh waters. Batch adsorption data from solutions of metals mixtures fitted the Langmuir model with adsorption capacities in the following order, TNF ≫ zeolite > basalt; Pb > Cu > Cd, Ni, Zn.
Stewart, MG 2017, 'Risk of Progressive Collapse of Buildings from Terrorist Attacks: Are the Benefits of Protection Worth the Cost?', Journal of Performance of Constructed Facilities, vol. 31, no. 2.
View/Download from: Publisher's site
View description>>
The paper describes a probabilistic risk assessment model to identify the risks associated with vehicle-borne improvised explosive device (VBIED) attacks to large federal government buildings in the United States. Probability of terrorist threat, hazard, damage, fatality, and economic and social loss for progressive collapse are modeled as stochastic variables. It was found that the existing annual fatality risk for building occupants is lower than acceptable risk criteria, and that progressive collapse is an exceedingly rare event in Western countries. A performance-based design using cost-benefit analysis of U.S. design provisions to mitigate against progressive collapse showed that these design measures only becomes cost-effective when the threat likelihood is a very high 1 in 1,000 per building per year. However, such provisions are more likely to be cost-effective in regions of high seismicity due to a lower cost premium.
Stewart, MG & Mueller, J 2017, 'Risk and economic assessment of expedited passenger screening and TSA PreCheck', Journal of Transportation Security, vol. 10, no. 1-2, pp. 1-22.
View/Download from: Publisher's site
View description>>
The Transportation Security Administration’s PreCheck program allows airline passengers assessed as low risk to be directed to faster screening lanes. The paper assesses the scenario of a terrorist plot to down an airliner with a passenger-borne bomb. There are four main conclusions. First, we find that the layered system currently in place reduces the risk of such an attack by 98% - and probably by quite a bit more. Second, this level of risk reduction is very robust: security remains high even when the parameters that make it up are varied considerably. In particular, because of the large array of other security layers, overall risk reduction is relatively insensitive to how effective checkpoint screening is. Third, under most realistic combinations of parameter values PreCheck actually increases risk reduction, perhaps up to 1%, while under the worst assumptions, it lowers risk reduction by some 0.3%. Fourth, the co-benefits of the PreCheck program are very substantial: by greatly reducing checkpoint costs and by improving the passenger experience, this benefit can exceed several billion dollars per year. We also find that adding random exclusion and managed inclusion to the PreCheck program has little effect on the program’s risk reducing capability one way or the other. TSA PreCheck thus seems likely to bring efficiencies to the screening process and great benefits to passengers, airports, and airlines while actually enhancing security.
Stuart, BH & Thomas, PS 2017, 'Pigment characterisation in Australian rock art: a review of modern instrumental methods of analysis', Heritage Science, vol. 5, no. 1, pp. 1-6.
View/Download from: Publisher's site
View description>>
© 2017 The Author(s). The many thousands of Aboriginal rock art sites extending across Australia represent an important cultural record. The styles and materials used to produce such art are of great interest to archaeologists and those concerned with the protection of these significant works. Through an analysis of the mineral pigments utilised in Australian rock art, insight into the age of paintings and practices employed by artists can be gained. In recent years, there has been an expansion in the use of modern analytical techniques to investigate rock art pigments and this paper provides a review of the application of such techniques to Australian sites. The types of archaeological information that may be extracted via chemical analysis of specimens collected from or at rock art sites across the country are discussed. A review of the applicability of the techniques used for elemental analysis and structural characterisation of rock art pigments is provided and how future technological developments will influence the discipline is investigated.
Su, Y, Li, J, Wu, C, Wu, P, Tao, M & Li, X 2017, 'Mesoscale study of steel fibre-reinforced ultra-high performance concrete under static and dynamic loads', Materials & Design, vol. 116, pp. 340-351.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd In this paper, a three-dimensional numerical model to study the static and dynamic behaviour of ultra-high performance steel fibre reinforced concrete is developed. Ultra-high performance steel fibre reinforced concrete is assumed to be a two-phase model consisting of concrete matrix and steel fibres. The concrete matrix is modelled with homogeneous material and the straight round steel fibres are assumed to be dispersed with random locations and orientations in the matrix. The interfacial transition zone (ITZ) effect is studied based on the single fibre pull-out tests, and parameters describing the fibre-matrix one dimensional bond-slip behaviour are obtained and discussed based on both experimental and theoretical results. After the three-dimensional model is validated with static split tensile tests, split Hopkinson pressure bar (SHPB) split tensile tests are numerically modelled and the stress-time history is interpreted in the mesoscale level. The proposed model qualitatively and quantitatively predicts the material static and dynamic behaviours, and also gives insights on the fibre reinforcement effect in the concrete matrix.
Su, Y, Wu, C, Li, J, Li, Z-X & Li, W 2017, 'Development of novel ultra-high performance concrete: From material to structure', Construction and Building Materials, vol. 135, pp. 517-528.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This paper investigates effects of nanoscale materials and steel fibres on properties of ultra-high performance concrete (UHPC). Different types of steel fibres including twisted steel fibre (TF), waved steel fibre (WF), and micro steel fibre (MF) together with different kinds of nano materials including Nano-CaCO3, Nano-SiO2, Nano-TiO2 and Nano-Al2O3 are studied in the present research. Material compressive stress–strain relationships, strain energy absorption, the flexural strength and fracture energy absorption of UHPC with different nanoscale materials and steel fibres were compared and discussed. Laboratory static bending tests and field blast tests on structural components made of selected UHPC material composition were carried out, and the results highlighted the superior material ductility and blast resistant capacity of UHPC material developed in the present study.
Sun, G, Pang, T, Fang, J, Li, G & Li, Q 2017, 'Parameterization of criss-cross configurations for multiobjective crashworthiness optimization', International Journal of Mechanical Sciences, vol. 124-125, pp. 145-157.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Thin-walled tubes have exhibited extraordinary advantages in lightweight and energy absorption for crashing scenarios. Geometric configuration of such tubal structures is of decisive effects on crashing behaviors. In this study, crashing characteristics of conventional square tube and a criss-cross tube were first conducted using both experimental and numerical analyses, through which the finite element (FE) models were well validated. It was also revealed that the energy absorption of the criss-cross sectional tube was about 150% higher than that of square column with the same weight. Further, a range of criss-cross sections were parametrically modeled with spline curves and a parametric study was subsequently performed to explore the effects of different parameterized shapes on crashing characteristics. It was found that the geometric parameters significantly affected crashworthiness of the criss-cross tubes, and the criss-cross tubes with a spline curve (CCT_SPL) surpass the criss-cross tubes with a straight line (CCT_STR) in crashworthiness with the same weight. Finally, to optimize the crashwo rthiness of parameterized criss-cross tubes, the non-dominated sorting genetic algorithm II (NSGA-II) was adopted to seek optimal criss-cross shapes for improving specific energy absorption (SEA) and reducing the peak crashing force (F max ), simultaneously. The optimization results indicate that the CCT_SPL profiles with reasonable geometric parameters are superior to the CCT_STR counterparts with an increase of 11.1% in specific energy absorption.
Sun, G, Zhang, H, Fang, J, Li, G & Li, Q 2017, 'Multi-objective and multi-case reliability-based design optimization for tailor rolled blank (TRB) structures', Structural and Multidisciplinary Optimization, vol. 55, no. 5, pp. 1899-1916.
View/Download from: Publisher's site
View description>>
© 2016 Springer-Verlag Berlin HeidelbergLight weight and crashworthiness signify two main challenges facing in vehicle industry, which often conflict with each other. In order to achieve light weight while improving crashworthiness, tailor rolled blank (TRB) has become one of the most potential lightweight technologies. To maximize the characteristics of TRB structures, structural optimization has been adopted extensively. Conventional optimization studies have mainly focused on a single loading case (SLC). In practice, however, engineering structures are often subjected to multiple loading cases (MLC), implying that the optimal design under a certain condition may no longer be an optimum under other loading cases. Furthermore, traditional deterministic optimization could become less meaningful or even unacceptable when uncertainties of design variables and noises of system parameters are present. To address these issues, a multi-objective and multi-case reliability-based design optimization (MOMCRBDO) was developed in this study to optimize the TRB hat-shaped structure. The radial basis function (RBF) metamodel was adopted to approximate the responses of objectives and constraints, the non-dominated sorting genetic algorithm II (NSGA-II), coupled with Monte Carlo Simulation (MCS), was employed to seek optimal reliability solutions. The optimal results show that the proposed method is not only capable of improving the reliability of Pareto solutions, but also enhancing the robustness under MLC.
Sun, J, Dai, X, Liu, Y, Peng, L & Ni, B-J 2017, 'Sulfide removal and sulfur production in a membrane aerated biofilm reactor: Model evaluation', Chemical Engineering Journal, vol. 309, pp. 454-462.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Sulfide removal from wastewater is essential, in view of the toxic, malodor and corrosive property of sulfide. The oxidation of sulfide by chemolithotrophic sulfide oxidation bacteria can produce elemental sulfur, an important chemical material. A membrane aerated biofilm reactor (MABR) has been successfully implemented and demonstrated for enhanced sulfide oxidation and sulfur production, owning to its counter-diffusion design of oxygen supply. In this work, a mathematical model was developed to evaluate the sulfide oxidation and sulfur production in the MABR in the presence of residual organics in the influent. The model was calibrated and validated using the experimental data from the long-term operation of the sulfide-oxidation MABR at different operational stages. The results suggested that the developed model could satisfactorily describe sulfide oxidation, sulfur production, sulfate accumulation and organics conversion in the MABR. The modelling results indicated that with the optimal combinations of sulfide loading and oxygen pressure, over 90% of sulfide removal and over 75% of sulfur recovery could be achieved. The sulfide oxidation and sulfur production would also be affected by the biofilm area to reactor volume (A/V) ratio in the MABR, with high A/V ratio might deteriorate the sulfur production efficiency depending on the oxygen pressure applied. Further, the increase of volatile fatty acids in the wastewater would not affect the sulfide oxidation efficiency but could enhance the sulfur production efficiency by decreasing the amount of sulfur oxidized to sulfate.
Sun, J, Dai, X, Peng, L, Liu, Y, Wang, Q & Ni, B-J 2017, 'A biofilm model for assessing perchlorate reduction in a methane-based membrane biofilm reactor', Chemical Engineering Journal, vol. 327, pp. 555-563.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. Perchlorate (ClO4−) is recognized as an important contaminant in surface water and groundwater, which would pose health risks at very low concentrations. A methane-based membrane biofilm reactor (MBfR) has been successfully demonstrated for perchlorate reduction, which provided an alternative solution for perchlorate remediation with low cost. In this work, a multispecies biofilm model was developed to evaluate perchlorate reduction in the methane-based MBfR under different operational conditions. The model was calibrated and validated using the experimental data from the long-term operation of the MBfR at seven distinct stages. The results suggested that the developed model could satisfactorily describe perchlorate reduction and denitrification performances in the MBfR (R2 > 0.9). The modeling results provided insight into the microbial community distribution in the biofilm, with aerobic methanotrophs and perchlorate reduction bacteria being mainly located at the membrane side (∼60%) and heterotrophic bacteria being situated near the liquid side (∼50%). The model simulations indicated that over 80% of perchlorate removal efficiency could be achieved through controlling the optimal combinations of methane pressure (PCH4) and perchlorate loading (LClO4) (e.g., applying a PCH4 of 30 kPa at a LClO4 of 0.08 g Cl/m2/d). In addition, the perchlorate reduction would be inhibited by the presence of nitrate and nitrite in the MBfR, which should be appropriately controlled during the future practical application of the promising process.
Sun, W-J, Zong, F-Y, Sun, D-A, Wei, Z-F, Schanz, T & Fatahi, B 2017, 'Swelling prediction of bentonite-sand mixtures in the full range of sand content', Engineering Geology, vol. 222, pp. 146-155.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The swelling prediction of bentonite–sand mixtures due to wetting is very important in evaluating the long term performance of the engineered barrier in the high level radioactive waste disposal system and the hydraulic barriers in geoenvironmental constructions. Sun et al. (2015) proposed the swelling prediction model of bentonite-sand mixtures due to full hydration, and predicted the swelling of different types of bentonite-sand mixtures, which was verified, to be consistent with the swelling test results. However, the predicted swelling results of bentonite-sand mixtures with extremely high sand content obtained by the original swelling prediction model have a large deviation from the test results. The reason is that the original model is based on an assumption that all the pores and available water are only associated with bentonite/montmorillonite fraction. However, for mixtures with extremely high sand content, the sand skeleton exists and resists the external stress from the very beginning. At the same time, the bentonite, dispersing in the sand skeleton, in contact with the pore fluid, swells freely to fully saturated state, however, still fails to fill the sand skeleton voids completely. In this research, the original swelling prediction model is extended by introducing the concept of critical filling sand content and critical contact stress. When sand content is more than the critical filling sand content, the deformation of the mixture is mainly due to the sand skeleton deformation. After the stress increases greater than the critical contact stress, the saturated bentonite fills the sand skeleton voids completely, and the swelling can still be predicted by the original swelling prediction model. In the extended model, the swelling prediction can be divided into three zones according to the two limit values of critical sand content and critical filling sand content. In different zones, the distribution ratio of the vertical stress ...
Sun, Y, Chen, C & Nimbalkar, S 2017, 'Identification of ballast grading for rail track', Journal of Rock Mechanics and Geotechnical Engineering, vol. 9, no. 5, pp. 945-954.
View/Download from: Publisher's site
View description>>
© 2017 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences Grading has long been recognised to critically influence the mechanical behaviour of ballast. To identify the ballast grading for heavy-haul rail track, monotonic and cyclic triaxial tests are conducted to assess the performances of different gradings. Permanent deformations, aggregates degradation, resilience, shear resistance, maximum and minimum densities are recorded and analysed. The grading is found to affect the behaviour of ballast in that coarser gradings exhibit relatively better strength, resilience and therefore less permanent deformation. However, ballast degradation increases with the overall aggregate size. Therefore, to identify the grading for ballast with different performance objectives, a grey relational theory is used to convert the multi-objective into single-objective, i.e. grey relational grade. A relatively optimal grading that provides the highest grey relational grade is thus suggested for the improved ballast performance.
Sun, Y, Indraratna, B, Carter, JP, Marchant, T & Nimbalkar, S 2017, 'Application of fractional calculus in modelling ballast deformation under cyclic loading', Computers and Geotechnics, vol. 82, pp. 16-30.
View/Download from: Publisher's site
Surawski, NC, Bezantakos, S, Barmpounis, K, Dallaston, MC, Schmidt-Ott, A & Biskos, G 2017, 'A tunable high-pass filter for simple and inexpensive size-segregation of sub-10-nm nanoparticles', Scientific Reports, vol. 7, no. 1.
View/Download from: Publisher's site
View description>>
AbstractRecent advanced in the fields of nanotechnology and atmospheric sciences underline the increasing need for sizing sub-10-nm aerosol particles in a simple yet efficient way. In this article, we develop, experimentally test and model the performance of a High-Pass Electrical Mobility Filter (HP-EMF) that can be used for sizing nanoparticles suspended in gaseous media. Experimental measurements of the penetration of nanoparticles having diameters down to ca 1nm through the HP-EMF are compared with predictions by an analytic, a semi-empirical and a numerical model. The results show that the HP-EMF effectively filters nanoparticles below a threshold diameter with an extremely high level of sizing performance, while it is easier to use compared to existing nanoparticle sizing techniques through design simplifications. What is more, the HP-EMF is an inexpensive and compact tool, making it an enabling technology for a variety of applications ranging from nanomaterial synthesis to distributed monitoring of atmospheric nanoparticles.
Syahir, AZ, Zulkifli, NWM, Masjuki, HH, Kalam, MA, Alabdulkarem, A, Gulzar, M, Khuong, LS & Harith, MH 2017, 'A review on bio-based lubricants and their applications', Journal of Cleaner Production, vol. 168, pp. 997-1016.
View/Download from: Publisher's site
View description>>
In transportation and industrial sectors, the world relies heavily on petroleum-based products which may cause grave concern related to future energy security. On certain cases, these products would end up back to the environment causing serious environmental pollution and hazards. Recognized as potential substitutes to mineral-based lubricants, bio-based lubricants have received growing interest as they play a significant role in overcoming above problems. Bio-based lubricants have been found to exhibit superior lubricant properties over the conventional mineral lubricants, with renewability and biodegradability being their strongest suit. There is a strong need to review the available literature to explore the potential of bio-based lubricants for various applications. In this regard, the goal of this paper is to highlight the potential of biolubricants for a broad range of applications based upon the published researches over the past decade. The correlation between molecular structures, physicochemical properties and lubrication performance of natural oil were reviewed which is essential for lubricant development and selection. This review also acknowledged some applications of which the potential use of bio-based lubricant has been explored. Based on the key findings, it can be concluded that bio-based lubricant is a promising substitute for various applications due to their availability in wide arrays of properties which are essential for some applications. However, for certain applications, prior chemical modification is required to overcome the limitations including substandard low temperature characteristics and oxidative stability. With proper base oil and additive packages formulation, bio-based lubricants can perform better than the conventional lubricants.
Tabatabaiefar, HR 2017, 'Development of synthetic soil mixture for experimental shaking table tests on building frames resting on soft soils', Geomechanics and Geoengineering, vol. 12, no. 1, pp. 28-35.
View/Download from: Publisher's site
View description>>
In this study, a synthetic soil mixture has been developed and proposed for experimental soil-structure interaction shaking table tests on building frames with shallow foundations resting on soft soil deposits. To find the most appropriate mixture, different mixes with different proportion of mix components were examined in soils laboratory. Performing bender element tests, shear wave velocity of the soil specimens were acquired at different cure ages and the results were examined and compared. Based on the test results, a synthetic clay mixture consisting of kaolinite clay, bentonite, fly ash, lime and water has been proposed for experimental shaking table tests. The proposed mix provides adequate undrained shear strength to mobilise the required shallow foundation bearing capacity underneath the structural model while meeting both criteria of dynamic similarity between the model and the prototype to model soft soils in shaking table tests.
Tabatabaiefar, HR, Mansoury, B, Khadivi Zand, MJ & Potter, D 2017, 'Mechanical properties of sandwich panels constructed from polystyrene/cement mixed cores and thin cement sheet facings', Journal of Sandwich Structures & Materials, vol. 19, no. 4, pp. 456-481.
View/Download from: Publisher's site
View description>>
Sandwich panels are made of two materials that are relatively weak in their separated state, but are improved when they are constructed together in a sandwich panel. Sandwich panels can be used for almost any section of a building including roofs, walls and floors. These building components are regularly required to provide insulation properties, weatherproofing properties and durability in addition to providing structural load bearing characteristics. Polystyrene/cement mixed cores and thin cement sheet facings sandwich panels are Australian products made of cement-polystyrene beaded mixture encapsulated between two thick cement board sheets. The structural properties of sandwich panels constructed of polystyrene/cement cores and thin cement sheet facings are relatively unknown. Therefore, in this study, to understand the mechanical behaviour and properties of those sandwich panels, a series of experimental tests have been performed and the outcomes have been explained and discussed. Based on the results of this study, values for modulus of elasticity and ultimate strength of the sandwich panels in dry and saturated conditions have been determined and proposed for practical applications.
Tan, ES, Anwar, M, Kumaran, P, Indra, TM & Yoshikawa, K 2017, 'Air assist atomization characterization of palm biodiesel through experimental investigation and CFD simulation', Biofuels, vol. 8, no. 5, pp. 571-577.
View/Download from: Publisher's site
View description>>
© 2016 Informa UK Limited, trading as Taylor & Francis Group. The depletion of fossil fuel and environmental concerns have elevated biodiesel to emerge as a suitable alternative fuel to substitute diesel fuel. The study of spray formation is essential to improve the combustion systems of internal combustion engines and gas turbines. This paper aims to study the atomization characteristics of biodiesel derived from palm biodiesel through experimental test and simulation. The chemical fuel properties of biodiesel such as viscosity and density, will adversely affect the spray characteristics such as spray pattern, spray length, spray angle and Sauter Mean Diameter. The biodiesel fuels are blended with diesel in various ratios before being tested in an atomization test rig. Modelling of the atomizer are presented using computational fluid dynamics whereby comparisons are made with respect to the experimental results carried out in the atomizer test rig. There is no large discrepancy with the simulation results. The results showed that the higher content of biodiesel gives a larger droplet size and longer spray length. However, it produces smaller spray angle and spray width but with clearer vortex shape of spray pattern.
Tan, ES, Kumaran, P, Indra, TM & Yoshikawa, K 2017, 'Effect of Non-Edible Biodiesel Physical and Chemical Properties as Microturbine Fuel', Energy Procedia, vol. 142, pp. 413-418.
View/Download from: Publisher's site
View description>>
The world is facing critical energy concern, in view of depleting fossil fuel reserves and increasing environment pollution. Biodiesel can potentially substitute fossil fuel, and is produced through the transesterification of vegetable oils. This paper will emphasize on the transition from first generation derived from waste cooking oil, to second generation biodiesel derived from calophyllum inophyllum, which is a non-edible plant. The objective of this paper is to optimize the performance of biodiesel blends with diesel in a 30 kW microturbine. The characterization of chemical fuel properties of distillate and biodiesel blends will be conducted to determine if it meets international standards for power generation. Temperature profiles, pressure, and flame imaging will be closely monitored to detect possible problems in operability of the combustor caused by the differences in fuel characteristics. The findings may provide useful information towards optimization of microturbine performance, considering the wide range of biodiesel feedstock that exist. The paper outcome will show the potential of non-edible biodiesel blends to be used as alternative fuel in microturbines for power generation.
Tang, J, Wang, XC, Hu, Y, Ngo, HH & Li, Y 2017, 'Dynamic membrane-assisted fermentation of food wastes for enhancing lactic acid production', Bioresource Technology, vol. 234, pp. 40-47.
View/Download from: Publisher's site
View description>>
A dynamic membrane (DM) module was inserted into a fermentation reactor to separate soluble products from the fermented mixture to increase lactic acid (LA) production from food wastes under acidogenic conditions (uncontrolled pH, pH 4 and 5). With a high total suspended solid content (20-40g/L) in the fermenter, a stable DM could be maintained through regular backwashing. By effectively intercepting suspended solids and lactic acid bacteria (LAB), the fermenter was able to increase microbial activity and largely promote LA yield. Hydrolysis and acidogenesis rates increased with pH, and the highest LA yield (as high as 0.57g/g-TS) was obtained at pH 4. The microbial community analysis showed that the relative abundance of Lactobacillus increased to 96.4% at pH 4, but decreased to 43.3% at pH 5. In addition, the DM could be easily recovered by intercepting larger particles in less than 2h after each cycle of periodic backwashing.
Tang, J, Wang, XC, Hu, Y, Ngo, HH, Li, Y & Zhang, Y 2017, 'Applying fermentation liquid of food waste as carbon source to a pilot-scale anoxic/oxic-membrane bioreactor for enhancing nitrogen removal: Microbial communities and membrane fouling behaviour', Bioresource Technology, vol. 236, pp. 164-173.
View/Download from: Publisher's site
View description>>
Fermentation liquid of food waste (FLFW) was applied as an external carbon source in a pilot-scale anoxic/oxic-membrane bioreactor (A/O-MBR) system to enhance nitrogen removal for treating low COD/TN ratio domestic wastewater. Results showed that, with the FLFW addition, total nitrogen removal increased from lower than 20% to 44-67% during the 150days of operation. The bacterial metabolic activities were obviously enhanced, and the significant change in microbial community structure promoted pollutants removal and favored membrane fouling mitigation. By monitoring transmembrane pressure and characterizing typical membrane foulants, such as extracellular polymeric substances (EPS), dissolved organic matter (DOM), and inorganics and biopolymers in the cake layer, it was confirmed that FLFW addition did not bring about any additional accumulation of membrane foulants, acceleration of fouling rate, or obvious irreversible membrane fouling in the whole operation period. Therefore, FLFW is a promising alternative carbon source to enhance nitrogen removal for the A/O-MBR system.
Teh, SH, Wiedmann, T, Castel, A & de Burgh, J 2017, 'Hybrid life cycle assessment of greenhouse gas emissions from cement, concrete and geopolymer concrete in Australia', Journal of Cleaner Production, vol. 152, pp. 312-320.
View/Download from: Publisher's site
Tian, J, Wang, B, Zhao, F, Ma, X, Liu, Y, Liu, HK & Huang, Z 2017, 'Highly active Fe3BO6 as an anode material for sodium-ion batteries', Chemical Communications, vol. 53, no. 34, pp. 4698-4701.
View/Download from: Publisher's site
View description>>
An efficient Fe3BO6 anode with high capacity and excellent rate capability is studied, for the first time, for sodium-ion batteries.
Tien Bui, D, Bui, Q-T, Nguyen, Q-P, Pradhan, B, Nampak, H & Trinh, PT 2017, 'A hybrid artificial intelligence approach using GIS-based neural-fuzzy inference system and particle swarm optimization for forest fire susceptibility modeling at a tropical area', Agricultural and Forest Meteorology, vol. 233, pp. 32-44.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. This paper proposes and validates a novel hybrid artificial intelligent approach, named as Particle Swarm Optimized Neural Fuzzy (PSO-NF), for spatial modeling of tropical forest fire susceptibility. In the proposed approach, a Neural Fuzzy inference system (NF) was used to establish the forest fire model whereas Particle Swarm Optimization (PSO) was adopted to investigate the best values for the model parameters. Tropical forest at the province of Lam Dong (Central Highland of Vietnam) was used as a case study. For this purpose, historic forest fires and ten ignition factors (slope, aspect, elevation, land use, Normalized Difference Vegetation Index, distance to road, distance to residence area, temperature, wind speed, and rainfall) were collected from various sources to construct a GIS database, and then, the database was used to develop and validate the proposed model. The performance of the forest model was assessed using the Receiver Operating Characteristic curve, area under the curve (AUC), and several statistical measures. The results showed that the proposed model performs well, both on the training dataset (AUC = 0.932) and the validation dataset (AUC = 0.916). The usability of the proposed model was further assessed through comparisons with those derived from two benchmark state-of-the art machine learning methods, Random Forests (RF) and Support Vector Machine (SVM). Because the performance of the proposed model is better than the two benchmark models, we concluded that the PSO-NF model is a valid alternative tool that should be considered for tropical forest fire susceptibility modeling. The result in this study is useful for forest planning and management in forest fire prone areas.
Tien Bui, D, Tuan, TA, Hoang, N-D, Thanh, NQ, Nguyen, DB, Van Liem, N & Pradhan, B 2017, 'Spatial prediction of rainfall-induced landslides for the Lao Cai area (Vietnam) using a hybrid intelligent approach of least squares support vector machines inference model and artificial bee colony optimization', Landslides, vol. 14, no. 2, pp. 447-458.
View/Download from: Publisher's site
View description>>
© 2016, Springer-Verlag Berlin Heidelberg. The main objective of this study is to produce a landslide susceptibility map for the Lao Cai area (Vietnam) using a new hybrid intelligent method based on least squares support vector machines (LSSVM) and artificial bee colony (ABC) optimization, namely LSSVM-BC. LSSVM and ABC are state-of-the-art soft computing techniques that have been rarely utilized in landslide susceptibility assessment. LSSVM is adopted to develop landslide prediction model whereas ABC was used to optimize the prediction model by identifying an appropriate set of the LSSVM hyper-parameters. To establish the hybrid intelligent method, a GIS database with ten landslide-influencing factors and 340 landslide locations that occurred mainly during the last 20-years was constructed. These historical landslide locations were collected from the existing inventories that sourced from (i) five landslide projects carried out in this study areas before and (ii) interpretations of SPOT satellite images with resolution of 2.5 m. The study area was geographically split into two different parts, with landslides located in the first part was used for building models whereas the other landslides in the second part was used for the model validation. Performance of the LSSVM-BC model was assessed using the receiver operating characteristic (ROC) curve and area under the curve (AUC). Result shows that the prediction power of the model is good with the area under the curve (AUC) = 0.900. Experiments have pointed out the prediction power of the LSSVM-BC is better than that obtained from the popular support vector machines. Therefore, the proposed model is a promising tool for spatial prediction of landslides at the study area. The landslide susceptibility map is useful for landuse planning for the Lao Cai area.
Tran, HN, You, S-J, Nguyen, TV & Chao, H-P 2017, 'Insight into the adsorption mechanism of cationic dye onto biosorbents derived from agricultural wastes', Chemical Engineering Communications, vol. 204, no. 9, pp. 1020-1036.
View/Download from: Publisher's site
View description>>
© 2017 Taylor & Francis. This study investigated the phenomenon and mechanism of adsorption of methylene green 5 (MG5) on three pristine biosorbents: golden shower pod (GS), coconut shell (CC), and orange peel (OP). The results showed that the biosorbents possessed low specific surface areas, but abundant functional groups. Adsorption was strongly affected by the solution’s pH and ionic strength. As revealed in the kinetic study, equilibrium was rapidly established, requiring low activation energies; a removal rate of 30%–87% was achieved within 1 min. The maximum Langmuir adsorption capacities at 30°C exhibited the following order: GS (106 mg/g) > OP (92 mg/g) > CC (59 mg/g). Thermodynamic experiments suggested that the adsorption occurred spontaneously and exothermically The primary adsorption mechanisms involved electrostatic attraction, hydrogen bonding formations, and n-π interaction. Thermogravimetric analysis (TGA) revealed that three biopolymer components (i.e., hemicellulose, cellulose, and lignin) played controlling roles in the adsorption process. Thus, these three agricultural residues can be considered potential low-cost adsorbents for efficient dye adsorption applications.
Tran, VH, Phuntsho, S, Park, H, Han, DS & Shon, HK 2017, 'Sulfur-containing air pollutants as draw solution for fertilizer drawn forward osmosis desalination process for irrigation use', Desalination, vol. 424, pp. 1-9.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. This study investigated suitability and performance of the sulfur-based seed solution (SBSS) as a draw solution (DS), a byproduct taken from the photoelectrochemical (PEC) process where the SBSS is used as an electrolyte for H2 production. This SBSS DS is composed of a mixture of ammonium sulfate ((NH4)2SO4) and ammonium sulfite ((NH4)2SO3), and it can be utilized as fertilizer for fertilizer drawn forward osmosis (FDFO) desalination of saline water. The FDFO process employed with thin-film composite (TFC) membrane and showed that the process performance (i.e. water flux and reverse salt flux) is better than that with cellulose triacetate (CTA) membrane. In addition, it produced high water flux of 19 LMH using SBSS as DS at equivalent concentration at 1 M and 5 g/L NaCl of feed solution (model saline water). Experimental results showed that the reverse salt flux of SBSS increased with the increase in pH of the DS and that lowering the concentration of ammonium sulfite in the SBSS led to the higher water flux of feed solution. The result also demonstrated that this SBSS is practically suitable for the FDFO process toward development of water-energy-food nexus technology using sulfur chemicals-containing air pollutant.
Tran, VS, Ngo, HH, Guo, W, Ton-That, C, Li, J, Li, J & Liu, Y 2017, 'Removal of antibiotics (sulfamethazine, tetracycline and chloramphenicol) from aqueous solution by raw and nitrogen plasma modified steel shavings', Science of The Total Environment, vol. 601-602, pp. 845-856.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. The removal of sulfamethazine (SMT), tetracycline (TC) and chloramphenicol (CP) from synthetic wastewater by raw (M3) and nitrogen plasma modified steel shavings (M3-plN2) was investigated using batch experiments. The adsorption kinetics could be expressed by both pseudo-first-order kinetic (PFO) and pseudo-second-order kinetic (PSO) models, where correlation coefficient r2 values were high. The values of PFO rate constant k1p and PSO rate constant k2p decreased as SMT-M3 > SMT-M3-plN2 > TC-M3-plN2 > TC-M3 > CP-M3 > CP-M3-plN2 and SMT-M3 > SMT-M3-plN2 > TC-M3 > TC-M3-plN2 > CP-M3 > CP-M3-plN2, respectively. Solution pH, adsorbent dose and temperature exerted great influences on the adsorption process. The plasma modification with nitrogen gas cleaned and enhanced 1.7-fold the surface area and 1.4-fold the pore volume of steel shavings. Consequently, the removal capacity of SMT, TC, CP on the adsorbent rose from 2519.98 to 2702.55, 1720.20 to 2158.36, and 2772.81 to 2920.11 μg/g, respectively. Typical chemical states of iron (XPS in Fe2p3 region) in the adsorbents which are mainly responsible for removing antibiotics through hydrogen bonding, electrostatic and non- electrostatic interactions and redox reaction were as follows: Fe3O4/Fe2 +, Fe3O4/Fe3 +, FeO/Fe2 + and Fe2O3/Fe3 +.
Trung Ngo, N, Indraratna, B & Rujikiatkamjorn, C 2017, 'Closure to “Micromechanics-Based Investigation of Fouled Ballast Using Large-Scale Triaxial Tests and Discrete Element Modeling” by Ngoc Trung Ngo, Buddhima Indraratna, and Cholachat Rujikiatkamjorn', Journal of Geotechnical and Geoenvironmental Engineering, vol. 143, no. 9, pp. 07017027-07017027.
View/Download from: Publisher's site
Uchiyama, M, Satoh, K, McKenzie, TG, Fu, Q, Qiao, GG & Kamigaito, M 2017, 'Diverse approaches to star polymers via cationic and radical RAFT cross-linking reactions using mechanistic transformation', Polymer Chemistry, vol. 8, no. 38, pp. 5972-5981.
View/Download from: Publisher's site
View description>>
Core cross-linked star polymers were synthesizedviacationic RAFT polymerization and three different approaches in combination with a radical RAFT mechanism.
Vahedian, A, Shrestha, R & Crews, K 2017, 'Effective bond length and bond behaviour of FRP externally bonded to timber', Construction and Building Materials, vol. 151, pp. 742-754.
View/Download from: Publisher's site
View description>>
Despite a large number of studies on estimating the effective bond length from the characteristics of the component materials, key parameters governing the effective bond length for FRP-to-timber joint have not been suggested by any of the current Codes and developed theories to date mostly cover FRP-to-concrete joints. Also, most theoretical bond strength models have been derived based on effective bond length. Therefore, to achieve a satisfactory bonded joint, the effectiveness of bond length is required to be accurately considered. This research study investigates 136 FRP-to-timber joints subjected to pull-out tests in order to determine the stress and strain distribution profiles along the interface and subsequently analyses the results to undertake direct measurement of the effective bond length. In addition, a modified test set up has been developed and is presented. A novel theoretical model has been established through regression analysis of bond length data and accordingly a new predictive model for effective bond length for FRP-to-timber joints has been developed. A comparative analysis between the results of the experimental pull-out tests results and those predicted from the analytical model indicates a satisfactory correlation is achieved between measured and predicted effective bond length, verifying the validity of the new model.
Vahedian, A, Shrestha, R & Crews, K 2017, 'Modelling of Factors Affecting Bond Strength of Fibre Reinforced Polymer Externally Bonded to Timber and Concrete', International Journal of Structural and Construction Engineering, vol. 11, no. 12, pp. 1635-1642.
View description>>
In recent years, fibre reinforced polymers asapplications of strengthening materials have received significantattention by civil engineers and environmentalists because of theirexcellent characteristics. Currently, these composites have become amainstream technology for strengthening of infrastructures such assteel, concrete and more recently, timber and masonry structures.However, debonding is identified as the main problem which limitthe full utilisation of the FRP material. In this paper, a preliminaryanalysis of factors affecting bond strength of FRP-to-concrete andtimber bonded interface has been conducted. A novel theoreticalmethod through regression analysis has been established to evaluatethese factors. Results of proposed model are then assessed withresults of pull-out tests and satisfactory comparisons are achievedbetween measured failure loads (R2 = 0.83, P < 0.0001) and thepredicted loads (R2 = 0.78, P < 0.0001)
Vakhshouri, B & Nejadi, S 2017, 'Compressive strength and mixture proportions of self-compacting light weight concrete', Computers and Concrete, vol. 19, no. 5, pp. 555-566.
View/Download from: Publisher's site
View description>>
Copyright © 2017 Techno-Press, Ltd. Recently some efforts have been performed to combine the advantages of light-weight and self-compacting concrete in one package called Light-Weight Self-Compacting Concrete (LWSCC). Accurate prediction of hardened properties from fresh state characteristics is vital in design of concrete structures. Considering the lack of references in mixture design of LWSCC, investigating the proper mixture components and their effects on mechanical properties of LWSCC can lead to a reliable basis for its application in construction industry. This study utilizes wide range of existing data of LWSCC mixtures to study the individual and combined effects of the components on the compressive strength. From sensitivity of compressive strength to the proportions and interaction of the components, two equations are proposed to estimate the LWSCC compressive strength. Predicted values of the equations are in good agreement with the experimental data. Application of lightweight aggregate to reduce the density of LWSCC may bring some mixing problems like segregation. Reaching a higher strength by lowered density is a challenging problem that is investigated as well. The results show that, the compressive strength can be improved by increasing the of mixture density of LWSCC, especially in the range of density under 2000 Kg/m3.
Vakhshouri, B & Nejadi, S 2017, 'Instantaneous deflection of light-weight concrete slabs', Frontiers of Structural and Civil Engineering, vol. 11, no. 4, pp. 412-423.
View/Download from: Publisher's site
View description>>
© 2017, Higher Education Press and Springer-Verlag GmbH Germany. Construction loading before the age of 28 d can have the most significant effects on the slabs, especially for multi-story structures. The changing properties of the young concrete complicate the prediction of serviceability design requirements also. An experimental investigation is performed on four simply supported Light-Weight Concrete (LWC) one-way slabs subjected to immediate loading at 14 d. Effects of aggregate type, loading levels and cracking moment together with the influences of ultimate moment capacity and service moment on the instantaneous deflection of slabs are studied. Comparison of the obtained results with predictions of existing models in the literature shows considerable differences between the recorded and estimated instantaneous deflection of LWC slabs. Based on sensitivity analysis of the effective parameters, a new equation is proposed and verified to predict the instantaneous deflection of LWC slabs subjected to loading at the age of 14 d.
Van Ngoc, P, Turner, B, Huang, J & Kelly, R 2017, 'Experimental study on the durability of soil-cement columns in coastal areas', Geotechnical Engineering, vol. 48, no. 4, pp. 138-143.
View description>>
Deep soil mixing is one of the most commonly used ground improvement techniques. With high sulphate content in soil and seawater, stabilised soil in coastal areas can deteriorate due to sulphate attack. In this research, the degradation in strength of cement treated soil exposed to synthetic seawater is measured by uniaxial compression and needle penetration testing. Three exposure conditions, namely 100% seawater, 200% seawater and sealed condition (control samples), were used to measure the deterioration level due to the effect of sulphate. In addition, the extent of the portlandite consumption was also measured by Thermogravimetric Analysis which reflects the calcium distribution in the soil-cement columns. The test results show that the deterioration occurs deeper and faster in higher seawater environments. Furthermore, in contact with increasing sulphate concentration, the deterioration shows a close relation with calcium distribution.
Van Nguyen, Q, Fatahi, B & Hokmabadi, AS 2017, 'Influence of Size and Load-Bearing Mechanism of Piles on Seismic Performance of Buildings Considering Soil–Pile–Structure Interaction', International Journal of Geomechanics, vol. 17, no. 7, pp. 04017007-04017007.
View/Download from: Publisher's site
View description>>
© 2017 American Society of Civil Engineers. Pile foundations are usually used to transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata with a higher bearing capacity and stiffness. The type and size of a pile foundation that supports midrise buildings in high-risk seismic zones can alter the dynamic characteristics of the soil-pile-foundation system during an earthquake due to soil-structure interaction. To investigate these phenomena, a 15-story moment-resisting frame sitting on differently sized end-bearing and floating pile foundations was simulated numerically. The present paper describes a numerical modeling technique for the simulation of complex seismic soil-pile-structure interaction phenomena. By adopting a method of direct calculation, the numerical model can perform a fully nonlinear time history dynamic analysis to realistically simulate the dynamic behavior of soil, pile foundations, and structure under seismic excitations. This three-dimensional (3D) numerical model accounts for the nonlinear behavior of the soil medium, the piles, and the structural elements. Results show that the type and size of the pile elements influence the dynamic characteristics and seismic response of the building due to interaction between the soil, pile foundations, and the structure. The findings of this study can help engineers select the correct size and type of pile foundation while considering the seismic performance of buildings sitting on soft soil and aim at optimizing their design.
Vessalas, K, Sirivivatnanon, V & Baweja, D 2017, 'Influence of Permeability-Reducing Admixtures on Water Penetration in Concrete', ACI Materials Journal, vol. 114, no. 6, pp. 911-922.
View/Download from: Publisher's site
View description>>
Copyright © 2017, American Concrete Institute. All rights reserved. An experimental investigation was carried out on concrete into the effectiveness of integral permeability-reducing admixtures as possible alternatives to the traditional external waterproofers. The efficiency of hydrophobic water repellents and crystalline pore blockers were evaluated in concretes incorporating fixed water-cementitious materials ratio (w/cm) and different cementitious material types covering OPC, fly ash, and granulated blast-furnace slag. Three different test methods were employed to evaluate the water penetration resistance of concrete. To isolate the benefits that are achieved by varying the mixture design parameters, statistical factorial analysis of variances was carried out to discover the significance of each variable. Results indicated that the effect of w/cm and cementitious material is more pronounced compared to the addition of permeability-reducing admixtures. It was also demonstrated that the admixtures can be effective in reducing water penetration; however, their effect is varied in different mixtures. Caution must be exercised when using such admixtures in different concrete mixtures.
Vongphachanh, S, Das Gupta, A, Milne-Home, W, Ball, JE & Pavelic, P 2017, 'Hydrogeological reconnaissance of Sukhuma district, Champasak Province, Southern Laos', Journal of Hydrology New Zealand, vol. 56, no. 2, pp. 79-96.
View description>>
Sparse hydrogeological data is a significant limitation to the study of groundwater in many areas. The objective of this study was to assess the hydrogeology in Sukhuma District of Champasak Province in Southern Laos where such a limitation occurs. The connection between surface water and groundwater was assessed by comparing groundwater levels and river bed elevations. Groundwater recharge was estimated by the water table fluctuation method. The feasibility of remote sensing to address data limitations for the future study of groundwater in the region was also investigated by comparing the Mekong River flow and rainfall data with the Equivalent Water Height derived from the Gravity Recovery and Climate Experiment; soil moisture data obtained from the Global Land Data Assimilation System was also compared with rainfall and groundwater levels in Sukhuma District. The results show that some parts of Khamouan River bed are disconnected from the water table during the dry season, whereas the river bed is fully connected to the water table during the wet season. However, in the Pheung River, which flows into the Khamouan River upstream of the river gauge, the groundwater level is fully disconnected from the river bed in the dry season and partially connected in the wet season. Groundwater recharge estimates vary according to the specific yield values used for the aquifer. The comparison between in-situ hydrological measurement and remote sensing data provides insights into the general hydrogeological conditions. The comparison also provides useful information for future studies of the hydrogeology in Sukhuma District and Southern Laos, where field observation data are sparse, to support sustainable groundwater development in the region.
Vu, TM, Trinh, VT, Doan, DP, Van, HT, Nguyen, TV, Vigneswaran, S & Ngo, HH 2017, 'Removing ammonium from water using modified corncob-biochar', Science of The Total Environment, vol. 579, pp. 612-619.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Ammonium pollution in groundwater and surface water is of major concern in many parts of the world due to the danger it poses to the environment and people's health. This study focuses on the development of a low cost adsorbent, specifically a modified biochar prepared from corncob. Evaluated here is the efficiency of this new material for removing ammonium from synthetic water (ammonium concentration from 10 to 100 mg/L). The characteristics of the modified biochar were determined by Brunauer-Emmett-Teller (BET) test, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that ammonium adsorption on modified biochar strongly depended on pH. Adsorption kinetics of NH4+-N using modified biochar followed the pseudo-second order kinetic model. Both Langmuir and Sips adsorption isotherm models could simulate well the adsorption behavior of ammonium on modificated biochar. The highest adsorption capacity of 22.6 mg NH4+-N/g modified biochar was obtained when the biochar was modified by soaking it in HNO3 6 M and NaOH 0.3 M for 8 h and 24 h, respectively. The high adsorption capacity of the modified biochar suggested that it is a promising adsorbent for NH4+-N remediation from water.
Wang, C, Gao, B, Zhao, P, Li, R, Yue, Q & Shon, HK 2017, 'Exploration of polyepoxysuccinic acid as a novel draw solution in the forward osmosis process', RSC Advances, vol. 7, no. 49, pp. 30687-30698.
View/Download from: Publisher's site
View description>>
Polyepoxysuccinic acid (PESA) is a green corrosion scale inhibitor.
Wang, D, Fu, Q, Xu, Q, Liu, Y, Hao Ngo, H, Yang, Q, Zeng, G, Li, X & Ni, B-J 2017, 'Free nitrous acid-based nitrifying sludge treatment in a two-sludge system enhances nutrient removal from low-carbon wastewater', Bioresource Technology, vol. 244, no. Part 1, pp. 920-928.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd A new method to enhance nutrient removal from low carbon-wastewater was developed. The method consists of a two-sludge system (i.e., an anaerobic-anoxic-oxic reactor coupled to a nitrifying reactor (N-SBR)) and a nitrifying-sludge treatment unit using free nitrous acid (FNA). Initially, 65.1 ± 2.9% in total nitrogen removal and 69.6 ± 3.4% in phosphate removal were obtained without nitrite accumulation. When 1/16 of the nitrifying sludge was daily treated with FNA at 1.1 mg N/L for 24 h, ∼28.5% of nitrite was accumulated in the N-SBR, and total nitrogen and phosphate removal increased to 72.4 ± 3.2% and 76.7 ± 2.9%, respectively. About 67.8% of nitrite was accumulated at 1.9 mg N/L FNA, resulting in 82.9 ± 3.8% in total nitrogen removal and 87.9 ± 3.5% in phosphate removal. Fluorescence in-situ hybridization analysis showed that FNA treatment reduced the abundance of nitrite oxidizing bacteria (NOB), especially that of Nitrospira sp.
Wang, D, Liu, Y, Ngo, HH, Zhang, C, Yang, Q, Peng, L, He, D, Zeng, G, Li, X & Ni, B-J 2017, 'Approach of describing dynamic production of volatile fatty acids from sludge alkaline fermentation', Bioresource Technology, vol. 238, pp. 343-351.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd In this work, a mathematical model was developed to describe the dynamics of fermentation products in sludge alkaline fermentation systems for the first time. In this model, the impacts of alkaline fermentation on sludge disintegration, hydrolysis, acidogenesis, acetogenesis, and methanogenesis processes are specifically considered for describing the high-level formation of fermentation products. The model proposed successfully reproduced the experimental data obtained from five independent sludge alkaline fermentation studies. The modeling results showed that alkaline fermentation largely facilitated the disintegration, acidogenesis, and acetogenesis processes and severely inhibited methanogenesis process. With the pH increase from 7.0 to 10.0, the disintegration, acidogenesis, and acetogenesis processes respectively increased by 53%, 1030%, and 30% while methane production decreased by 3800%. However, no substantial effect on hydrolysis process was found. The model also indicated that the pathway of acetoclastic methanogenesis was more severely inhibited by alkaline condition than that of hydrogentrophic methanogenesis.
Wang, D, Wang, Y, Liu, Y, Ngo, HH, Lian, Y, Zhao, J, Chen, F, Yang, Q, Zeng, G & Li, X 2017, 'Is denitrifying anaerobic methane oxidation-centered technologies a solution for the sustainable operation of wastewater treatment Plants?', Bioresource Technology, vol. 234, pp. 456-465.
View/Download from: Publisher's site
View description>>
With the world's increasing energy crisis, society is growingly considered that the operation of wastewater treatment plants (WWTPs) should be shifted in sustainable paradigms with low energy input, or energy-neutral, or even energy output. There is a lack of critical thinking on whether and how new paradigms can be implemented in WWTPs based on the conventional process. The denitrifying anaerobic methane oxidation (DAMO) process, which uses methane and nitrate (or nitrite) as electron donor and acceptor, respectively, has recently been discovered. Based on critical analyses of this process, DAMO-centered technologies can be considered as a solution for sustainable operation of WWTPs. In this review, a possible strategy with DAMO-centered technologies was outlined and illustrated how this applies for the existing WWTPs energy-saving and newly designed WWTPs energy-neutral (or even energy-producing) towards sustainable operations.
Wang, H, Wu, C, Zhang, F, Fang, Q, Xiang, H, Li, P, Li, Z, Zhou, Y, Zhang, Y & Li, J 2017, 'Experimental study of large-sized concrete filled steel tube columns under blast load', Construction and Building Materials, vol. 134, pp. 131-141.
View/Download from: Publisher's site
View description>>
© 2016 This paper investigates blast resistance and residual strength of concrete-filled steel tube (CFST) columns under close-range blast loads. A total of 8 CFST columns, including 4 with circular cross sections and 4 with square cross sections, were tested under close-range blasts. LVDTs were used to record displacement histories and pressure sensors were used to measure pressure histories. The influence of explosive charge weight, steel tube thickness and cross section geometry on dynamic response of CFST columns was analyzed and failure modes of CFST columns were also investigated. Following the blast tests, an experimental study was conducted to investigate residual strength of blast-damaged CFST columns. It was found that the CFST columns were still able to retain a large portion of their axial load capacities even after close-range blast events.
Wang, J, Pathak, N, Chekli, L, Phuntsho, S, Kim, Y, Li, D & Shon, H 2017, 'Performance of a Novel Fertilizer-Drawn Forward Osmosis Aerobic Membrane Bioreactor (FDFO-MBR): Mitigating Salinity Build-Up by Integrating Microfiltration', Water, vol. 9, no. 1, pp. 21-21.
View/Download from: Publisher's site
View description>>
© 2017 by the authors. In this paper, three different fertilizer draw solutions were tested in a novel forward osmosis-microfiltration aerobic membrane bioreactor (MF-FDFO-MBR) hybrid system and their performance were evaluated in terms of water flux and reverse salt diffusion. Results were also compared with a standard solution. Results showed that ammonium sulfate is the most suitable fertilizer for this hybrid system since it has a relatively high water flux (6.85 LMH) with a comparatively low reverse salt flux (3.02 gMH). The performance of the process was also studied by investigating different process parameters: draw solution concentration, FO draw solution flow rate and MF imposed flux. It was found that the optimal conditions for this hybrid system were: draw solution concentration of 1 M, FO draw solution flow rate of 200 mL/min and MF imposed flux of 10 LMH. The salt accumulation increased from 834 to 5400 μS/cm during the first four weeks but after integrating MF, the salinity dropped significantly from 5400 to 1100 μS/cm suggesting that MF is efficient in mitigating the salinity build up inside the reactor. This study demonstrated that the integration of the MF membrane could effectively control the salinity and enhance the stable FO flux in the OMBR.
Wang, J, Yang, G, Liu, H, Shrawan Nimbalkar, S, Tang, X & Xiao, Y 2017, 'Seismic response of concrete-rockfill combination dam using large-scale shaking table tests', Soil Dynamics and Earthquake Engineering, vol. 99, pp. 9-19.
View/Download from: Publisher's site
Wang, Q 2017, 'A Roadmap for Achieving Energy-Positive Sewage Treatment Based on Sludge Treatment Using Free Ammonia', ACS Sustainable Chemistry & Engineering, vol. 5, no. 11, pp. 9630-9633.
View/Download from: Publisher's site
View description>>
This letter proposes an innovative roadmap for achieving energy-positive sewage treatment based on sludge treatment using free ammonia (FA, i.e., NH3). This FA technology is able to enhance anaerobic energy recovery in the form of methane via pretreatment of primary sludge and/or secondary sludge. It can also achieve stable mainstream nitrogen removal via nitrite instead of nitrate, thereby increasing organics availability for energy recovery. Energy evaluation suggests that the FA technology could transform sewage treatment plants from energy consumers (energy consumption at 0.27 kWh/m3 sewage treated) to energy exporters (energy export at 0.14 kWh/m3 sewage treated). Economic and environmental evaluations indicate that the FA technology would reduce sewage treatment cost and CO2 emission by $0.056/m3 sewage treated and 0.40 kg CO2/m3 sewage treated, respectively. This FA technology is a sustainable and closed-loop technology, which requires negligible chemical/energy input with FA being a byproduct of sewage treatment. It is also easy to implement in any existing and new sewage treatment plants by adding a simple sludge mixing tank.
Wang, Q, Duan, H, Wei, W, Ni, B-J, Laloo, A & Yuan, Z 2017, 'Achieving Stable Mainstream Nitrogen Removal via the Nitrite Pathway by Sludge Treatment Using Free Ammonia', Environmental Science & Technology, vol. 51, no. 17, pp. 9800-9807.
View/Download from: Publisher's site
View description>>
© 2017 American Chemical Society. Biological nitrogen removal through the nitrite pathway (NH4+ → NO2- → N2) is favorable for wastewater treatment plants without sufficient carbon sources. This study demonstrates an innovative approach for attaining the nitrite pathway based on sludge treatment using free ammonia (FA, i.e., NH3). This approach is based on our innovative discovery in this study that FA at 210 mg NH3-N/L is far less biocidal to ammonium-oxidizing bacteria (AOB) than to nitrite-oxidizing bacteria (NOB). A total of 22% of the activated sludge from the sequencing batch reactor (SBR) receiving synthetic domestic wastewater was treated in an FA treatment unit at 210 mg NH3-N/L for 1 day. The FA-treated sludge was afterward recirculated back to the SBR. A nitrite accumulation ratio of above 90% was quickly achieved (in 40 days) and maintained stably in the SBR, indicating the establishment of the nitrite pathway. The NOB population and activity after implementing FA treatment was less than 5% of those without FA treatment, suggesting the washout of NOB. In contrast, the AOB population and activity in the SBR were not affected. The nitrogen-removal performance was significantly improved after incorporating the FA approach. The FA approach is a closed-loop approach and is economically and environmentally attractive.
Wang, Q, Wei, W, Gong, Y, Yu, Q, Li, Q, Sun, J & Yuan, Z 2017, 'Technologies for reducing sludge production in wastewater treatment plants: State of the art', Science of The Total Environment, vol. 587-588, pp. 510-521.
View/Download from: Publisher's site
View description>>
This review presents the state-of-the-art sludge reduction technologies applied in both wastewater and sludge treatment lines. They include chemical, mechanical, thermal, electrical treatment, addition of chemical un-coupler, and predation of protozoa/metazoa in wastewater treatment line, and physical, chemical and biological pretreatment in sludge treatment line. Emphasis was put on their effect on sludge reduction performance, with 10% sludge reduction to zero sludge production in wastewater treatment line and enhanced TS (total solids) or volatile solids removal of 5-40% in sludge treatment line. Free nitrous acid (FNA) technology seems good in wastewater treatment line but it is only under the lab-scale trial. In sludge treatment line, thermal, ultrasonic (<4400kJ/kg TS), FNA pretreatment and temperature-phased anaerobic digestion (TPAD) are promising if pathogen inactivation is not a concern. However, thermal pretreatment and TPAD are superior to other pretreatment technologies when pathogen inactivation is required. The new wastewater treatment processes including SANI®, high-rate activated sludge coupled autotrophic nitrogen removal and anaerobic membrane bioreactor coupled autotrophic nitrogen removal also have a great potential to reduce sludge production. In the future, an effort should be put on the effect of sludge reduction technologies on the removal of organic micropollutants and heavy metals.
Wang, Q, Ye, X, Wang, S, Sloan, S & Sheng, D 2017, 'Development of a Model Test System for Studying the Behaviour of a Compaction Grouted Soil Nail under Unsaturated Conditions', Geotechnical Testing Journal, vol. 40, no. 5, pp. 20160229-20160229.
View/Download from: Publisher's site
Wang, Q, Ye, X, Wang, S, Sloan, SW & Sheng, D 2017, 'Experimental investigation of compaction-grouted soil nails', Canadian Geotechnical Journal, vol. 54, no. 12, pp. 1728-1738.
View/Download from: Publisher's site
View description>>
An innovative compaction-grouted soil nail was designed by injecting grout into a special latex balloon (grouting bag) to avoid bleeding and penetration of grout into the surrounding soil. A series of large-scale model tests was performed to study the surrounding soil responses due to grouting and the subsequent pull-out resistance of the soil nail. The experimental results show that grouting pressure plays an important role in the enhancement of the density and (or) strength of the surrounding soil. In addition, during the pull-out process, the compaction-grouted soil nail exhibits a strain-hardening behaviour without a yield point. This is a significant advantage of this new soil nail, indicating that it can enable soil masses to remain stable against a relatively large deformation before ultimate failure. The main factors behind the improvement of the pull-out resistance of the new soil nail are, first, the compaction–densification of the soil near the grouting bag due to grouting, resulting in the enhancement of the shear strength of the soil, and, second, the enlargement of the grouting bag, causing the increase of the interface shear and end resistance to the pull-out of the soil nail.
Wang, Y, Wang, C, Guo, H, Wang, Y & Huang, Z 2017, 'A nitrogen-doped three-dimensional carbon framework for high performance sodium ion batteries', RSC Advances, vol. 7, no. 3, pp. 1588-1592.
View/Download from: Publisher's site
View description>>
A nitrogen-doped three-dimensional carbon framework is synthesized, and shows good Na+ storage performance with excellent rate capability.
Wang, Y, Wang, D, Liu, Y, Wang, Q, Chen, F, Yang, Q, Li, X, Zeng, G & Li, H 2017, 'Triclocarban enhances short-chain fatty acids production from anaerobic fermentation of waste activated sludge', Water Research, vol. 127, pp. 150-161.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Triclocarban (TCC), one typical antibacterial agent being widely used in various applications, was found to be present in waste activated sludge at significant levels. To date, however, its effect on anaerobic fermentation of sludge has not been investigated. This work therefore aims to fill this knowledge gap. Experimental results showed that when TCC content in sludge increased from 26.7 ± 5.3 to 520.5 ± 12.6 mg per kilogram total suspended solids, the maximum concentration of short-chain fatty acids (SCFA) increased from 32.6 ± 2.5 to 228.2 ± 3.6 (without pH control) and from 211.7 ± 2.4 to 378.3 ± 3.2 mg COD/g VSS (initial pH 10), respectively. The large promotion of acetic acid was found to be the major reason for the enhancement of total SCFA production. Although a significant level of TCC was degraded in the fermentation process, SCFA was neither produced from TCC nor affected by its major intermediates at the relevant levels. It was found that TCC facilitated solubilization, acidogenesis, acetogenesis, and homoacetogenesis processes but inhibited methanogenesis process. Microbial analysis revealed that the increase of TCC increased the microbial community diversity, the abundances of SCFA (especially acetic acid) producers, and the activities of key enzymes relevant to acetic acid production.
Wang, Z, Wu, S, Huang, Y, Chen, Y, Shi, S, Cheng, X & Huang, R 2017, 'Evaporation and Ignition Characteristics of Water Emulsified Diesel under Conventional and Low Temperature Combustion Conditions', Energies, vol. 10, no. 8, pp. 1109-1109.
View/Download from: Publisher's site
View description>>
© 2017 by the authors. Licensee MDPI, Basel, Switzerland. The combination of emulsified diesel and low temperature combustion (LTC) technology has great potential in reducing engine emissions. A visualization study on the spray and combustion characteristics of water emulsified diesel was conducted experimentally in a constant volume chamber under conventional and LTC conditions. The effects of ambient temperature on the evaporation, ignition and combustion characteristics of water emulsified diesel were studied under cold, evaporating and combustion conditions. Experimental results showed that the ambient temperature had little effect on the spray structures, in terms of the liquid core length, the spray shape and the spray area. However, higher ambient temperature slightly reduced the Sauter Mean Diameter (SMD) of the spray droplets. The auto-ignition delay time increased significantly with the decrease of the ambient temperature. The ignition process always occurred at the entrainment region near the front periphery of the liquid core. This entrainment region was evolved from the early injected fuel droplets which were heated and mixed by the continuous entrainment until the local temperature and equivalence ratio reached the ignition condition. The maximum value of integrated natural flame luminosity (INFL) reduced by 60% when the ambient temperature dropped from 1000 to 800 K, indicating a significant decrease of the soot emissions could be achieved by LTC combustion mode than the conventional diesel engines.
Wei, D, Zhang, K, Ngo, HH, Guo, W, Wang, S, Li, J, Han, F, Du, B & Wei, Q 2017, 'Nitrogen removal via nitrite in a partial nitrification sequencing batch biofilm reactor treating high strength ammonia wastewater and its greenhouse gas emission', Bioresource Technology, vol. 230, pp. 49-55.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd In present study, the feasibility of partial nitrification (PN) process achievement and its greenhouse gas emission were evaluated in a sequencing batch biofilm reactor (SBBR). After 90 days’ operation, the average effluent NH4+-N removal efficiency and nitrite accumulation rate of PN-SBBR were high of 98.2% and 87.6%, respectively. Both polysaccharide and protein contents were reduced in loosely bound extracellular polymeric substances (LB-EPS) and tightly bound EPS (TB-EPS) during the achievement of PN-biofilm. Excitation-emission matrix spectra implied that aromatic protein-like, tryptophan protein-like and humic acid-like substances were the main compositions of both kinds of EPS in seed sludge and PN-biofilm. According to typical cycle, the emission rate of CO2had a much higher value than that of N2O, and their total amounts per cycle were 67.7 and 16.5 mg, respectively. Free ammonia (FA) played a significant role on the inhibition activity of nitrite-oxidizing bacteria and the occurrence of nitrite accumulation.
Wei, W, Zhou, X, Wang, D, Sun, J & Wang, Q 2017, 'Free ammonia pre-treatment of secondary sludge significantly increases anaerobic methane production', Water Research, vol. 118, pp. 12-19.
View/Download from: Publisher's site
View description>>
Energy recovery in the form of methane from sludge/wastewater is restricted by the poor and slow biodegradability of secondary sludge. An innovative pre-treatment technology using free ammonia (FA, i.e. NH3) was proposed in this study to increase anaerobic methane production. The solubilisation of secondary sludge was significantly increased after FA pre-treatment at up to 680 mg NH3-N/L for 1 day, under which the solubilisation (i.e. 0.4 mg SCOD/mg VS; SCOD: soluble chemical oxygen demand; VS: volatile solids) was >10 times higher than that without FA pre-treatment (i.e. 0.03 mg SCOD/mg VS). Biochemical methane potential assays showed that FA pre-treatment at above 250 mg NH3-N/L is effective in improving anaerobic methane production. The highest improvement in biochemical methane potential (B0) and hydrolysis rate (k) was achieved at FA concentrations of 420-680 mg NH3-N/L, and was determined as approximately 22% (from 160 to 195 L CH4/kg VS added) and 140% (from 0.22 to 0.53 d-1) compared to the secondary sludge without pre-treatment. More analysis revealed that the FA induced improvement in B0 and k could be attributed to the rapidly biodegradable substances rather than the slowly biodegradable substances. Economic and environmental analyses showed that the FA-based technology is economically favourable and environmentally friendly. Since this FA technology aims to use the wastewater treatment plants (WWTPs) waste (i.e. anaerobic digestion liquor) to enhance methane production from the WWTPs, it will set an example for the paradigm shift of the WWTPs from 'linear economy' to 'circular economy'.
Wei, W, Zhou, X, Xie, G, Duan, H & Wang, Q 2017, 'A novel free ammonia based pretreatment technology to enhance anaerobic methane production from primary sludge', Biotechnology and Bioengineering, vol. 114, no. 10, pp. 2245-2252.
View/Download from: Publisher's site
View description>>
ABSTRACTThis study proposed a novel free ammonia (FA, i.e., NH3) pretreatment technology to enhance anaerobic methane production from primary sludge for the first time. The solubilization of primary sludge was substantially enhanced following 24 h FA pretreatment (250–680 mg NH3‐N/L), by which the release of soluble chemical oxygen demand (SCOD) (i.e., 0.4 mg SCOD/mg VS added; VS: volatile solids) was approximately 10 times as much as that without pretreatment (i.e., 0.03 mg SCOD/mg VS added). Then, biochemical methane potential (BMP) tests demonstrated that FA pretreatment of 250–680 mg NH3‐N/L was capable of enhancing anaerobic methane production while the digestion time was more than 7 days. Model based analysis indicated that the improved anaerobic methane production was due to an increased biochemical methane potential (B0) of 8–17% (i.e., from 331 to 357–387 L CH4/kg VS added), with the highest B0 achieved at 420 mg NH3‐N/L pretreatment. However, FA pretreatment of 250–680 mg NH3‐N/L decreased hydrolysis rate (k) by 24–38% compared with control (i.e., from 0.29 d−1 to 0.18–0.22 d−1), which explained the lower methane production over the first 7 days’ digestion period. Economic analysis and environmental evaluation demonstrated that FA pretreatment technology was environmentally friendly and economically favorable. Biotechnol. Bioeng. 2017;114: 2245–2252. © 2017 Wiley Periodicals, Inc.
Wijayaratna, KP, Dixit, VV, Denant-Boemont, L & Waller, ST 2017, 'An experimental study of the Online Information Paradox: Does en-route information improve road network performance?', PLOS ONE, vol. 12, no. 9, pp. e0184191-e0184191.
View/Download from: Publisher's site
View description>>
This study investigates the empirical presence of a theoretical transportation paradox, defined as the 'Online Information Paradox' (OIP). The paradox suggests that, for certain road networks, the provision of online information deteriorate travel conditions for all users of that network relative to the situation where no online information is provided to users. The analytical presence of the paradox was derived for a specific network structure by using two equilibrium models, the first being the Expected User Equilibrium (EUE) solution (no information scenario) and the other being the User Equilibrium with Recourse (UER) solution (with information scenario). An incentivised computerised route choice game was designed using the concepts of experimental economics and administered in a controlled laboratory environment to investigate the physical presence of the paradox. Aggregate statistics of path flows and Total System Travel Costs (TSTC) were used to compare the experimental results with the theoretical findings. A total of 12 groups of 12 participants completed the experiment and the OIP and the occurrence of the OIP being significant was observed in 11 of the 12 cases. Though information increased travel costs for users on average, it reduced the volatility of travel costs experienced in the no information scenario indicating that information can achieve a more reliable system. Further replications of similar experiments and more importantly field based identification of the phenomena will force transport professionals to be aware of the emergence of the paradox. In addition, studies such as this emphasise the need for the adoption of adaptive traffic assignment techniques to appropriately model the acquisition of information on a road network.
Woo, YC, Tijing, LD, Park, MJ, Yao, M, Choi, J-S, Lee, S, Kim, S-H, An, K-J & Shon, HK 2017, 'Electrospun dual-layer nonwoven membrane for desalination by air gap membrane distillation', Desalination, vol. 403, pp. 187-198.
View/Download from: Publisher's site
View description>>
© 2015 Elsevier B.V. In the present study, dual-layer nanofiber nonwoven membranes were prepared by a facile electrospinning technique and applied for desalination by air gap membrane distillation (AGMD). Neat single and dual-layer nanofiber membranes composed of a hydrophobic polyvinylidene fluoride-co-hexafluoropropylene (PH) top layer with different supporting hydrophilic layer made of either polyvinyl alcohol (PVA), nylon-6 (N6), or polyacrylonitrile (PAN) nanofibers were fabricated with and without heat-press post-treatment. Surface characterization showed that the active layer (i.e., PH) of all electrospun nanofiber membranes (ENMs) exhibited a rough, highly porous (> 80% porosity), and hydrophobic surface (CA > 140°), while the other side was hydrophilic (CA < 90°) with varying porosity. Heat-pressing the membrane resulted to thinner thickness (from > 129 μm to < 100 μm) and smaller pore sizes (< 0.27 μm). The AGMD experiments in a co-current flow set-up were carried out with constant inlet temperatures at the feed and permeate streams of 60 ± 1.5 and 20 ± 1.5° C, respectively. The AGMD module had a membrane area of 21 cm2 and the thickness of the air gap was 3 mm. The neat single and dual-layer ENMs showed a water permeate flux of about 10.9–15.5 L/m2 h (LMH) using 3.5 wt.% NaCl solution as feed, which was much higher than that of a commercial PVDF membrane (~ 5 LMH). The provision of a hydrophilic layer at the bottom layer enhanced the AGMD performance depending on the wettability and characteristics of the support layer. The PH/N6 dual-layer nanofiber membrane prepared under the optimum condition showed flux and salt rejection of 15.5 LMH and 99.2%, respectively, which has good potential for AGMD application.
Wu, B, Gao, W, Wu, D & Song, C 2017, 'Probabilistic interval geometrically nonlinear analysis for structures', Structural Safety, vol. 65, pp. 100-112.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This paper presents a new unified Chebyshev surrogate model based hybrid uncertainty analysis method for robustly assessing geometrically nonlinear responses of engineering structures involving both random and interval uncertainties. In this proposed approach, Chebyshev response surface strategy combined with finite element framework is developed to model the nonlinear relationships between the uncertain structural parameters and the corresponding system responses. A comprehensive computational analysis framework, namely generalized unified interval stochastic sampling, is devised to furnish the statistical features, including means, standard deviations, probability density functions and cumulative distribution functions, of the lower and upper bounds of the nonlinear random interval structural behaviours. The applicability and notable performance of the presented approach are elucidated with the help of two practically motivated examples.
Wu, B, Ni, B-J, Horvat, K, Song, L, Chai, X, Dai, X & Mahajan, D 2017, 'Occurrence State and Molecular Structure Analysis of Extracellular Proteins with Implications on the Dewaterability of Waste-Activated Sludge', Environmental Science & Technology, vol. 51, no. 16, pp. 9235-9243.
View/Download from: Publisher's site
View description>>
© 2017 American Chemical Society. The occurrence state and molecular structure of extracellular proteins were analyzed to reveal the influencing factors on the water-holding capacities of protein-like substances in waste-activated sludge (WAS). The gelation process of extracellular proteins verified that advanced oxidation processes (AOPs) for WAS dewaterability improvement eliminated the water affinity of extracellular proteins and prevented these macromolecules from forming stable colloidal aggregates. Isobaric tags for relative and absolute quantitation proteomics identified that most of the extracellular proteins were originally derived from the intracellular part and the proteins originally located in the extracellular part were mainly membrane-associated. The main mechanism of extracellular protein transformation during AOPs could be represented by the damage of the membrane or related external encapsulating structure and the release of intracellular substances. For the selected representative extracellular proteins, the strong correlation (R2 > 0.97, p < 0.03) between the surface hydrophilicity index and α-helix percentages in the secondary structure indicated that the water affinity relied more on the spatial distribution of hydrophilic functional groups rather than the content. Destructing the secondary structure represented by the α-helix and stretching the polypeptide aggregation in the water phase through disulfide bond removal might be the key to eliminating the inhibitory effects of extracellular proteins on the interstitial water removal from WAS.
Wu, C & Li, J 2017, 'Structural Protective Design with Innovative Concrete Material and Retrofitting Technology', Procedia Engineering, vol. 173, pp. 49-56.
View/Download from: Publisher's site
View description>>
© 2017 The Authors. Retrofitting technology and high performance construction material are now widely investigated so as to increase structural ductility and robustness under extreme loading conditions. In the present study, some recent developments in structural protection against blast loads are compiled. Metallic foam materials with varying foam density and gradient are used in the cladding design, their energy absorbing capacities and stress-strain relationships are studied based on uniaxial compression tests. These foam material are used to cast sacrificial claddings on the concrete slabs in the field blast tests. Damage and structural deformation are measured to check the effectiveness of the claddings. Besides sacrificial foam cladding, concrete material with new reinforcement scheme including steel wire mesh and micro steel fiber is developed, and the static test results indicates the excellent ductility and crack control ability of this novel design. In the field blast tests, concrete slabs with different steel wire mesh reinforcement are exposed to varying blast loads. The effectiveness of the slab reinforcing design is discussed based on field performance.
Wu, C, Gao, Y, Fang, J, Lund, E & Li, Q 2017, 'Discrete topology optimization of ply orientation for a carbon fiber reinforced plastic (CFRP) laminate vehicle door', Materials & Design, vol. 128, pp. 9-19.
View/Download from: Publisher's site
Wu, C, Li, J, Hao, H & Li, Z-X 2017, 'Preface', International Journal of Protective Structures, vol. 8, no. 3, pp. 323-324.
View/Download from: Publisher's site
Wu, D & Gao, W 2017, 'Hybrid uncertain static analysis with random and interval fields', Computer Methods in Applied Mechanics and Engineering, vol. 315, pp. 222-246.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Uncertain static analysis of an engineering structure with diverse type of non-deterministic system parameter is investigated in this study. Unlike the traditional hybrid uncertain static analysis involving random and interval variables, the concept of random and interval fields has been implemented to model the spatially dependent uncertainties associated with the system inputs. A novel computational approach, namely the extended unified interval stochastic sampling (X-UISS) method, is proposed to calculate the statistical characteristics (i.e., mean and standard deviation) of the extreme bounds (i.e., lower and upper bounds) of the concerned responses (e.g., displacement and stress) of engineering structure involving hybrid spatially dependent uncertainties. Subsequently, by utilizing either parametric or nonparametric statistical analysis, the probability density functions (PDFs), as well as the cumulative distribution functions (CDFs), of the extreme bounds of the concerned structural responses can be effectively established. Consequently, the upper and lower bounds of either the concerned responses of the engineering structure at any particular percentile of probability, or the structural reliability against any specified capacities can be effectively secured. The applicability and effectiveness of the proposed computational analysis framework are illustrated through the numerical investigations on various examples.
Wu, D, Gao, W & Tangaramvong, S 2017, 'Time-Dependent Buckling Analysis of Concrete-Filled Steel Tubular Arch with Interval Viscoelastic Effects', Journal of Structural Engineering, vol. 143, no. 7, pp. 04017055-04017055.
View/Download from: Publisher's site
View description>>
In this paper, a finite-element-based computational method is proposed for time-dependent structural stability analysis of a concrete-filled steel tubular (CFST) arch with uncertain parameters. Specifically, the targeted uncertainty includes the mercurial effects of the creep and shrinkage of the concrete core, which inevitably affect the structural performance of the CFST arch. The structural stability of the composite arch is systematically investigated under the influence of uncertain creep and shrinkage in a time-dependent fashion. The proposed computational scheme efficiently establishes the quantitative long-term stability envelope for CFST arches against uncertain viscoelastic effects. In order to demonstrate the effectiveness and efficiency of the proposed time-dependent structural stability analysis for CFST arches, practically motivated numerical examples are thoroughly investigated throughout this work.
Wu, D, Gao, W, Gao, K & Tin-Loi, F 2017, 'Robust safety assessment of functionally graded structures with interval uncertainties', Composite Structures, vol. 180, pp. 664-685.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This paper investigates the problem of non-deterministic static analysis of functionally graded structures involving interval uncertainties through both Euler-Bernoulli and Timoshenko beam theories. Within the generalized analysis framework of the Finite Element Method (FEM), a novel computational scheme is developed to effectively tackle such intricate, yet frequently encountered, engineering problems. The proposed method establishes a unified non-stochastic uncertainty analysis framework, which can incorporate the interval uncertainties of material properties of the functionally graded structural members, the dimensions of structural elements, as well as the externally applied thermal and mechanical loads. By introducing an alternative FEM formulation, the governing equation for the interval uncertain static analysis of functionally graded structures can be meticulously transformed into two standard nonlinear programming (NLP) problems, so the extreme bounds of any concerned structural behaviours can be effectively determined. In addition, the proposed method is able to provide the critical information regarding the uncertain parameters that are actually causing such extreme structural behaviours at zero computational cost. Consequently, such by-products of the analysis can certainly be beneficial for subsequent structural design, and also the physical feasibility of the original problem can be rigorously maintained.
Wu, H, Zhang, J, Ngo, HH, Guo, W & Liang, S 2017, 'Evaluating the sustainability of free water surface flow constructed wetlands: Methane and nitrous oxide emissions', Journal of Cleaner Production, vol. 147, pp. 152-156.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Constructed wetlands (CWs) have been used as a green technology to treat various wastewaters for several decades, and greenhouse gases production in these systems attracted increasing attention considering the contributions of methane and nitrous oxide emissions to global warming. However, the detailed knowledge about the contribution of CWs to methane and nitrous oxide emissions in treating sewage treatment plant effluent are still limited in particular for a better understanding of the sustainability of CWs. The fluxes of methane (CH 4 ) and nitrous oxide (N 2 O) from free water surface (FWS) CWs in northern China were measured continuously using the static-stationary chamber technique from 2012 to 2013. The results showed that CWs were the significant source of CH 4 and N 2 O emissions. Average emission rates of CH 4 and N 2 O ranged from −30.2 μg m −2 h −1 to 450.9 μg m −2 h −1 , and -58.8 μg m −2 h −1 to 1251.8 μg m −2 h −1 , respectively. Obvious annual and seasonal variations of CH 4 and N 2 O emissions were observed over the 2-year period. In addition, temperatures and plant species had an impact on CH 4 and N 2 O emissions. The obtained results showed that FWS CWs, improving water quality but emitting lower CH 4 and N 2 O, could be the alternative method for sewage treatment plant effluent.
Wu, Y, Yang, Q, Zeng, Q, Ngo, HH, Guo, W & Zhang, H 2017, 'Enhanced low C/N nitrogen removal in an innovative microbial fuel cell (MFC) with electroconductivity aerated membrane (EAM) as biocathode', Chemical Engineering Journal, vol. 316, pp. 315-322.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. A novel microbial fuel cell (MFC) was developed to enhance simultaneous nitrification and denitrification (SND) by employing electrons from the anode. The cathode chamber of the reactor consisted of a membrane aerated biofilm reactor (MABR) which was made of an electroconductivity aerated membrane. The maximum power density of 4.20 ± 0.12 W m −3 was obtained at a current density of 4.10 ± 0.11 A m −2 (external resistance = 10 Ω). Compared with an open-circuit system, the removal rates of NH 4 + -N and TN were improved by 9.48 ± 0.33% and 19.80 ± 0.84%, respectively, which could be ascribed to the electrochemical denitrification. The anode (chemical oxygen demand, COD) and cathode (NO 3 − ) chambers reached the maximum coulombic efficiencies (CEs) of 40.67 ± 1.05% and 42.84 ± 1.14%, respectively. It suggested that the electroconductivity MABR has some advantages in controlling aeration intensity, thus improving SND and CEs. Overall, EAM-MFC could successfully generate electricity from wastewater whilst showing high capacity for removing nitrogen at a low COD/N ratio of 2.8 ± 0.07 g COD g −1 N.
Xia, Y, Wu, C & Bennett, T 2017, 'An analytical model of linear density foam–protected structure under blast loading', International Journal of Protective Structures, vol. 8, no. 3, pp. 454-472.
View/Download from: Publisher's site
View description>>
Aluminium foam is widely known as an energy absorptive material which can be used as a protective cladding on structures to enhance blast resistance of the protected structures. Previous studies show that higher density provides larger energy absorption capacity of aluminium foam, but results in a larger transmitted pressure to the protected structure. To lower the transmitted pressure without sacrificing the maximum energy absorption, graded density foam has been examined in this study. An analytical model is developed in this article to investigate the protective effect of linear density foam on response of a structure under blast loading. The model is able to simulate structural deformation with reasonable accuracy compared with experimental data. The sensitivity of density gradient of foam cladding on reinforced concrete structure is tested in the article.
Xie, K, Fu, Q, Kim, J, Lu, H, He, Y, Zhao, Q, Scofield, J, Webley, PA & Qiao, GG 2017, 'Increasing both selectivity and permeability of mixed-matrix membranes: Sealing the external surface of porous MOF nanoparticles', Journal of Membrane Science, vol. 535, pp. 350-356.
View/Download from: Publisher's site
View description>>
A novel approach to improve the selectivity of mixed matrix membrane (MMM) systems was developed. MOF nanoparticles (NPs) were chemical coated by a PEG based shell and then incorporated into a polymer matrix to yield a MMM. The unique design of the core-shell MOF NPs can enhance both the membrane permeability and selectivity simultaneously. This membrane material exhibits excellent CO2/N2 separation performance that surpasses the latest upper bound through the most direct way. This filler was also applied to the thin-film composite membrane system, showing promising performance and placing it in the optimal zone for post-combustion CO2 capture.
Xu, B, Ahmed, MB, Zhou, JL, Altaee, A, Wu, M & Xu, G 2017, 'Photocatalytic removal of perfluoroalkyl substances from water and wastewater: Mechanism, kinetics and controlling factors', Chemosphere, vol. 189, pp. 717-729.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This review focuses on heterogeneous photocatalysis of perfluoroalkyl substances (PFAS) which are of worldwide concern as emerging persistent organic contaminants. Heterogeneous photocatalysis is an effective and advanced technology for PFAS removal from water with relatively high efficacy. During photocatalysis, various short chain perfluorocarboxylic acids (PFCA) are produced as intermediates and the efficacy is related to the photo-generated hole (h+) and photo-generated electron (e−). PFAS photodegradation in water under UV irradiation is most effective by using In2O3 as the catalyst, followed by Ga2O3 and TiO2. Significantly, modifying the chemical composition or morphology of the catalyst can improve its efficacy for PFAS removal. In2O3 porous nanoplates were found to have the best performance of 100% PFAS decomposition under UV light with rate constant (kt) and half-time (τ1/2) of 0.158 min−1 and 4.4 min, respectively. Catalysts perform well in acidic solution and increasing temperature to a certain extent. The photocatalytic performance is reduced when treating wastewater due to the presence of dissolved organic matter (DOM), with the catalysts following the order: needle-like Ga2O3 > In2O3 > TiO2. Future studies should focus on the development of novel photocatalysts, and their immobilization and application for PFAS removal in wastewater.
Xu, J, Wu, C, Li, J & Cui, J 2017, 'Simplified finite element method analysis of ultra-high-performance fibre-reinforced concrete columns under blast loads', Advances in Structural Engineering, vol. 20, no. 1, pp. 139-151.
View/Download from: Publisher's site
View description>>
Ultra-high-performance fibre-reinforced concrete has exceptional mechanical properties including high compressive and tensile strength as well as high fracture energy. It has been proved to be much higher blast resistant than normal concrete. In this article, flexural behaviours of ultra-high-performance fibre-reinforced concrete columns were investigated through full-scale tests. Two 200 mm × 200 mm × 2500 mm columns with and without axial loading were investigated under three-point bending tests, and their load–displacement relationships were recorded and the moment curvatures were derived. The derived moment curvature relationships of ultra-high-performance fibre-reinforced concrete columns were then incorporated into a computationally efficient one-dimensional finite element model, which utilized Timoshenko beam theory, to determine flexural response of ultra-high-performance fibre-reinforced concrete columns under blast loading. After that, the one-dimensional finite element model was validated with the real blast testing data. The results show good correlation between the advanced finite element model and experimental results. The feasibility of utilizing the one-dimensional finite element model for simulating both high-strength reinforced concrete and ultra-high-performance fibre-reinforced concrete columns against blast loading conditions is confirmed.
Xu, Q, Li, X, Ding, R, Wang, D, Liu, Y, Wang, Q, Zhao, J, Chen, F, Zeng, G, Yang, Q & Li, H 2017, 'Understanding and mitigating the toxicity of cadmium to the anaerobic fermentation of waste activated sludge', Water Research, vol. 124, pp. 269-279.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd Cadmium (Cd) is present in significant levels in waste activated sludge, but its potential toxicities on anaerobic fermentation of sludge remain largely unknown. This work therefore aims to provide such support. Experimental results showed that the impact of Cd on short-chain fatty acids (SCFA) production from sludge anaerobic fermentation was dose-dependent. The presence of environmentally relevant level of Cd (e.g., 0.1 mg/g VSS) enhanced SCFA production by 10.6%, but 10 mg/g VSS of Cd caused 68.1% of inhibition. Mechanism exploration revealed that although all levels of Cd did not cause extra leakage of intracellular substrates, 0.1 mg/g VSS Cd increased the contents of both soluble and loosely-bound extracellular polymeric substances (EPS), thereby benefitting sludge solubilization. On the contrary, 10 mg/g VSS Cd decreased the levels of all EPS layers, which reduced the content of soluble substrates. It was also found that 0.1 mg/g VSS Cd benefited both the hydrolysis and acidogenesis but 10 mg/g VSS Cd inhibited all the hydrolysis, acidogenesis, and methanogenesis processes. Further investigations with microbial community and enzyme analysis showed that the pertinent presence of Cd enhanced the activities of protease, acetate kinase, and oxaloacetate transcarboxylase whereas 10 mg/g VSS Cd decreased the microbial diversity, the abundances of functional microbes, and the activities of key enzymes. Finally, one strategy that could effectively mitigate the adverse impact of high Cd levels on SCFA production was proposed and examined. This work provides insights into Cd-present sludge fermentation systems, and the findings obtained may guide engineers to manipulate sludge treatment systems in the future.
Xu, R, Chen, J & Zhu, X 2017, 'A hybrid approach for parameter optimization of multiple tuned mass dampers in reducing floor vibrations due to occupant walking: Theory and parametric studies', Advances in Structural Engineering, vol. 20, no. 8, pp. 1232-1246.
View/Download from: Publisher's site
View description>>
This article presents a hybrid approach for determining optimal parameters of multiple tuned mass dampers to reduce the floor vibration due to human walking. The proposed approach consists of two parts. The first one is a partial mode decomposition algorithm to efficiently calculate dynamic responses of the coupled floor–multiple tuned mass damper system subjected to moving walking loads. The second one is an adaptive genetic simulated annealing method for the optimization of multiple tuned mass damper parameters. To establish optimization, certain variables must be considered. These include the mass, natural frequency, and damping ratio of each tuned mass damper in a multiple tuned mass damper system. The objective is to minimize floor responses and remove unreasonable requirements, such as uniform mass distribution and symmetric distribution of the tuned mass damper frequency. The proposed hybrid approach has successfully been applied to optimize the multiple tuned mass damper system to reduce the vibration of a long-span floor with closely spaced modes. By the hybrid approach, an extensive parametric study has been carried out. The results show that different walking load models and uncertainties in the dynamic properties of the floor and each tuned mass damper itself can affect the overall performance of the multiple tuned mass damper system. The proposed hybrid optimization approach is very effective and the resulting multiple tuned mass damper system is robust in reducing floor vibrations under various conditions.
Xu, S, Liu, Z & Wu, C 2017, 'Numerical simulation and test validation for ultra-high performance steel fiber reinforced concrete-filled double skin steel tube column under blast loading', Zhendong yu Chongji/Journal of Vibration and Shock, vol. 36, no. 1, pp. 45-54.
View/Download from: Publisher's site
View description>>
A 3D FE model was developed to analyze dynamic response and damage mechanism of a UHPSFRCFDST(Ultra-High Performance Steel Fiber Reinforced Concrete Filled Double Skin Steel Tube)column under blast loading, they were validated through comparison of simulated results and blast testing ones of the UHPSFRCFDST column. The effects of main variables including hollow ratios, steel ratios, and thicknesses and strengths of inner steel tube and outer steel one on the blast resistant performance of the UHPSFRCFDST column were investigated by utilizing the 3D FE model. The results indicated that the UHPSFRCFDST column has excellent anti-blast performances, and the proposed 3D FEM model can be used to analyze the dynamic response of the UHPSFRCFDST column under blast loading efficiently; reducing hollow ratio and increasing strength of outer steel tube in certain ranges can enhance effectively the blast resistant performance of the UHPSFRCFDST column; increasing steel ratio and reducing height to thickness ratios of inner and outer steel tubes can significantly improve the blast resistant performance of the UHPSFRCFDST column; the strength of inner steel tube has a little effect on the blast resistant performance of the UHPSFRCFDST column, but increasing the strength of outer steel tube in a certain range can improve the blast resistant performance of the UHPSFRCFDST column significantly.
Xu, S, Wu, C, Liu, Z, Han, K, Su, Y, Zhao, J & Li, J 2017, 'Experimental investigation of seismic behavior of ultra-high performance steel fiber reinforced concrete columns', Engineering Structures, vol. 152, pp. 129-148.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This paper presents an experimental study on seismic behavior of ultra-high performance steel fiber reinforced concrete (UHPSFRC) columns. Based on a series of cyclic loading tests on 14 UHPSFRC specimens subjected to combined static axial loading and cyclic lateral loading, the investigation and analysis have been carried out on crack status, failure modes, hysteretic loops, skeleton curves, strength and stiffness degradation, energy dissipation capacity and ductility of UHPSFRC columns. The influence of stirrup spacing, type of stirrup, axial compression ratio and shear span ratio on the seismic performance of UHPSFRC columns was also investigated in details. The experiment results show that three typical failure modes are observed, i.e., flexural, flexural-shear and shear failure mode. The existence of steel fiber could prevent the cracked concrete from spalling efficiently and delay the bulking of longitudinal reinforcement further. It noteworthy that the limit plastic drift ratio of all columns changes from 0.036 to 0.061, indicating that the UHPSFRC columns represent a good ductility which is obviously different from the conventional high strength concrete columns that exhibit much more brittleness with the increase of strength.
Xu, X-J, Chen, C, Wang, A-J, Ni, B-J, Guo, W-Q, Yuan, Y, Huang, C, Zhou, X, Wu, D-H, Lee, D-J & Ren, N-Q 2017, 'Mathematical modeling of simultaneous carbon-nitrogen-sulfur removal from industrial wastewater', Journal of Hazardous Materials, vol. 321, pp. 371-381.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. A mathematical model of carbon, nitrogen and sulfur removal (C-N-S) from industrial wastewater was constructed considering the interactions of sulfate-reducing bacteria (SRB), sulfide-oxidizing bacteria (SOB), nitrate-reducing bacteria (NRB), facultative bacteria (FB), and methane producing archaea (MPA). For the kinetic network, the bioconversion of C-N by heterotrophic denitrifiers (NO3− → NO2− → N2), and that of C-S by SRB (SO42− → S2−) and SOB (S2− → S0) was proposed and calibrated based on batch experimental data. The model closely predicted the profiles of nitrate, nitrite, sulfate, sulfide, lactate, acetate, methane and oxygen under both anaerobic and micro-aerobic conditions. The best-fit kinetic parameters had small 95% confidence regions with mean values approximately at the center. The model was further validated using independent data sets generated under different operating conditions. This work was the first successful mathematical modeling of simultaneous C-N-S removal from industrial wastewater and more importantly, the proposed model was proven feasible to simulate other relevant processes, such as sulfate-reducing, sulfide-oxidizing process (SR-SO) and denitrifying sulfide removal (DSR) process. The model developed is expected to enhance our ability to predict the treatment of carbon-nitrogen-sulfur contaminated industrial wastewater.
Xu, Y, Radjenovic, J, Yuan, Z & Ni, B-J 2017, 'Biodegradation of atenolol by an enriched nitrifying sludge: Products and pathways', Chemical Engineering Journal, vol. 312, pp. 351-359.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Biodegradation of β-blocker atenolol was investigated using an enriched nitrifying culture at controlled ammonium concentration and without ammonium addition. Analysis of the kinetics and structural elucidation of biodegradation products showed that atenolol biodegradation was found to be linked to the activity of nitrifying bacteria in the presence of ammonium. Atenolol was degraded cometabolically by ammonia-oxidizing bacteria (AOB), likely due to a broad substrate range of ammonia monooxygenase (AMO). Four products were formed during atenolol biodegradation with ammonia oxidation, including P267 (atenolol acid) and three new products P117 (1-isopropylamino-2-propanol), P167 (1-amino-3-phenoxy-2-propanol), and an unknown product P227 with a nominal molecular mass of 227. In comparison, only P267 and P227 were identified during atenolol biodegradation without ammonia oxidation. Follow-up experiments using atenolol acid as the parent compound indicated the formation of products P117, P167 and P227 in the presence of ammonium. Based on the products identified, a tentative biodegradation pathway of atenolol is suggested, which involves two steps independent of the presence of ammonium: i) microbial amide-bond hydrolysis to carboxyl group and formation of P267 (atenolol acid) and ii) a possible formation of P227 with its unidentified structure and other two cometabolically induced reactions: iii) breakage of ether bond in the alkyl side chain and formation of P117 and iv) a minor pathway through N-dealkylation and loss of acetamide moiety from the aromatic ring, yielding P167. This study provided an important insight regarding the biotransformation pathways under different metabolic conditions.
Xu, Y, Yuan, Z & Ni, B-J 2017, 'Biotransformation of acyclovir by an enriched nitrifying culture', Chemosphere, vol. 170, pp. 25-32.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd This work evaluates the biodegradation of the antiviral drug acyclovir by an enriched nitrifying culture during ammonia oxidation and without the addition of ammonium. The study on kinetics was accompanied with the structural elucidation of biotransformation products through batch biodegradation experiments at two different initial levels of acyclovir (15 mg L−1 and 15 μg L−1). The pseudo first order kinetic studies of acyclovir in the presence of ammonium indicated the higher degradation rates under higher ammonia oxidation rates than those constant degradation rates in the absence of ammonium. The positive correlation was found between acyclovir degradation rate and ammonia oxidation rate, confirming the cometabolism of acyclovir by the enriched nitrifying culture in the presence of ammonium. Formation of the product carboxy-acyclovir (P239) indicated the main biotransformation pathway was aerobic oxidation of the terminal hydroxyl group, which was independent on the metabolic type (i.e. cometabolism or metabolism). This enzyme-linked reaction might be catalyzed by monooxygenase from ammonia oxidizing bacteria or heterotrophs. The formation of carboxy-acyclovir was demonstrated to be irrelevant to the acyclovir concentrations applied, indicating the revealed biotransformation pathway might be the dominant removal pathway of acyclovir in wastewater treatment.
Xu, Y, Yuan, Z & Ni, B-J 2017, 'Impact of Ammonium Availability on Atenolol Biotransformation during Nitrification', ACS Sustainable Chemistry & Engineering, vol. 5, no. 8, pp. 7137-7144.
View/Download from: Publisher's site
View description>>
© 2017 American Chemical Society. The impact of ammonium availability on atenolol biotransformation at an environmentally relevant level of 15 μgL-1 by enriched nitrifying cultures was investigated in terms of atenolol degradation kinetics and biotransformation product formation dynamics. Different concentrations of growth substrate ammonium (0, 25, and 50 mg-NL-1) were applied constantly during batch experiments. The results suggested the higher ammonium concentrations led to lower atenolol removal rates probably due to the substrate competition between ammonium and atenolol. The formation of the biotransformation product atenolol acid was positively related to the ammonium oxidation activity, resulting in a higher amount at the end of experiments at higher ammonium concentrations. Linear correlations between ammonia oxidation rate and atenolol degradation rate at ammonium levels of 25 and 50 mg-NL-1 suggested the cometabolism of atenolol by ammonia oxidizing bacteria (AOB) in the presence of ammonium. The biotransformation reaction, i.e., hydroxylation on amide group to carboxylic group, could be catalyzed by the nonspecific ammonia monooxygenase (AMO) of AOB. Comparison between atenolol degradation at ammonium levels of 0 and 50 mg-NL-1 demonstrated the formation of atenolol acid was independent of the ammonium availability. This work might give further indication of how to prevent pharmaceuticals from entering into the environment.
Yang, S, Phan, HV, Bustamante, H, Guo, W, Ngo, HH & Nghiem, LD 2017, 'Effects of shearing on biogas production and microbial community structure during anaerobic digestion with recuperative thickening', Bioresource Technology, vol. 234, pp. 439-447.
View/Download from: Publisher's site
View description>>
Recuperative thickening can intensify anaerobic digestion to produce more biogas and potentially reduce biosolids odour. This study elucidates the effects of sludge shearing during the thickening process on the microbial community structure and its effect on biogas production. Medium shearing resulted in approximately 15% increase in biogas production. By contrast, excessive or high shearing led to a marked decrease in biogas production, possibly due to sludge disintegration and cell lysis. Microbial analysis using 16S rRNA gene amplicon sequencing showed that medium shearing increased the evenness and diversity of the microbial community in the anaerobic digester, which is consistent with the observed improved biogas production. By contrast, microbial diversity decreased under either excessive shearing or high shearing condition. In good agreement with the observed decrease in biogas production, the abundance of Bacteroidales and Syntrophobaterales (which are responsible for hydrolysis and acetogenesis) decreased due to high shearing during recuperative thickening.
Yang, Y-C, Chen, C-C, Huang, C-S, Wang, C-T & Ong, H-C 2017, 'Developments of metallic anodes with various compositions and surfaces for the microbial fuel cells', International Journal of Hydrogen Energy, vol. 42, no. 34, pp. 22235-22242.
View/Download from: Publisher's site
Yao, K, Pradhan, B & Idrees, MO 2017, 'Identification of Rocks and Their Quartz Content in Gua Musang Goldfield Using Advanced Spaceborne Thermal Emission and Reflection Radiometer Imagery', Journal of Sensors, vol. 2017, pp. 1-8.
View/Download from: Publisher's site
View description>>
Quartz is an important mineral element and the most abundant rock-forming mineral that controls the mineralogy of a reservoir. At the surface, quartz is more stable than most other rock minerals because it is made up of interlocking silica that makes it quite resistant to mechanical weathering. Quartz abundance is an indication of mineralization in many metal deposits; therefore, identification and mapping of quartz in rocks are of great value for exploration and resource potential assessments. In this study, thermal infrared (TIR) bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery were used to identify quartz contained rocks in Gua Musang. First, the image was corrected for atmospheric effect and the study area subset for further processing. Thereafter, spectral transformation (principal component analysis (PCA)) was implemented on the TIR bands and the resulting principal component (PC) images were analysed. The three optimal PCs were selected using the strength of spectral interaction and the eigenvalues of each band. To discriminate between quartz-rich and quartz-poor rocks, RGB false colour composite and greyscale image of one of the PCs were analysed. The result shows that volcanogenic igneous rock and carbonate sedimentary rocks of Permian formation are quartz-poor while Triassic sedimentary rock made up of organic particles and sandstone is quartz-rich. On the contrary, the quartz content in the metamorphic rock varies across the area but is richer in quartz content than the igneous and carbonate rocks. Classification of the composite image classified using maximum likelihood (ML) supervised classification method produced overall accuracy and Kappa coefficient of 96.53%, and 0.95, respectively.
Yao, M, Woo, Y, Tijing, L, Cesarini, C & Shon, H 2017, 'Improving Nanofiber Membrane Characteristics and Membrane Distillation Performance of Heat-Pressed Membranes via Annealing Post-Treatment', Applied Sciences, vol. 7, no. 1, pp. 78-78.
View/Download from: Publisher's site
View description>>
© 2017 by the authors. Electrospun membranes are gaining interest for use in membrane distillation (MD) dueto their high porosity and interconnected pore structure however, they are still susceptible towetting during MD operation because of their relatively low liquid entry pressure (LEP). In thisstudy, post-treatment had been applied to improve the LEP, as well as its permeation and saltrejection efficiency. The post-treatment included two continuous procedures: heat-pressing andannealing. In this study, annealing was applied on the membranes that had been heat-pressed.It was found that annealing improved the MD performance as the average flux reached 35 L/m2hor LMH (>10% improvement of the ones without annealing) while still maintaining 99.99% saltrejection. Further tests on LEP, contact angle, and pore size distribution explain the improvementdue to annealing well. Fourier transform infrared spectroscopy and X-ray diffraction analysesof the membranes showed that there was an increase in the crystallinity of the polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP) membrane also, peaks indicating the α phase ofpolyvinylidene fluoride (PVDF) became noticeable after annealing, indicating some βand amorphousstates of polymer were converted into the α phase. The changes were favorable for membranedistillation as the non-polar α phase of PVDF reduces the dipolar attraction force between themembrane and water molecules, and the increase in crystallinity would result in higher thermalstability. The present results indicate the positive effect of the heat-press followed by an annealingpost-treatment on the membrane characteristics and MD performance.
Ye, X, Wang, S, Wang, Q, Sloan, SW & Sheng, D 2017, 'Numerical and experimental studies of the mechanical behaviour for compaction grouted soil nails in sandy soil', Computers and Geotechnics, vol. 90, pp. 202-214.
View/Download from: Publisher's site
View description>>
A model test was conducted for a newly developed soil nail, the result of which was compared to that of a 3D finite element method (FEM) simulation. The shape angle (β) and friction coefficients (μ) contributed to the difference in pull-out force between the model test and the simulation. Further verifications were conducted, during which the pull-out mechanisms of the soil nail for different β and μ were analysed. It was found that both β and μ have a positive influence on the pull-out force; β only affects the increase rate, while μ influences the overall pull-out force level. Three components were found to govern the pull-out force, with the component applied to the expanded cement bulk surface accounting for approximately 80% of the total. This study proves that the optimal approach for increasing pull-out force is to enlarge the diameter of the cement bulk rather than extend the nail length.
Ye, X, Wang, S, Yang, J, Sheng, D & Xiao, C 2017, 'Soil Conditioning for EPB Shield Tunneling in Argillaceous Siltstone with High Content of Clay Minerals: Case Study', International Journal of Geomechanics, vol. 17, no. 4, pp. 1-8.
View/Download from: Publisher's site
View description>>
Soil clogging occurred in the early construction stage of Nanchang Metro Line 1, China, when an earth balance pressure (EPB) shield passed through the argillaceous siltstone with a total content of clay minerals of 40.5%. This paper presents a new scheme for determining soil conditioning parameters to avoid the occurrence of soil clogging, taking both the slump value and the liquidity index of the soil into account. As indicated by the results of slump tests, the optimum slump value for the soil conditioning ranged from 17 to 20 cm, and a fitting function of slump value against foam injection ratio (FIR) and water content (w) was obtained. Considering the requirement for a liquidity index equal to ~0.4-0.75 to ensure the stability of the excavation face, a chart was proposed for the soil conditioning. Based on the chart, the optimum FIR and w for the soil conditioning for tunneling in argillaceous siltstone were determined to be ~19.2-23.2% and ~14.2-36.6%, respectively. Taking shield parameters, tunnel design, and soil parameters into account, the soil conditioning techniques were implemented in field conditions. The field implementation indicated that soil clogging was effectively avoided in the later section of Nanchang Metro Line 1, and the thrust and torque of the shield were reduced significantly.
Ye, Y, Ngo, HH, Guo, W, Liu, Y, Li, J, Liu, Y, Zhang, X & Jia, H 2017, 'Insight into chemical phosphate recovery from municipal wastewater', Science of The Total Environment, vol. 576, pp. 159-171.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier B.V. Phosphate plays an irreplaceable role in the production of fertilizers. However, its finite availability may not be enough to satisfy increasing demands for the fertilizer production worldwide. In this scenario, phosphate recovery can effectively alleviate this problem. Municipal wastewater has received high priority to recover phosphate because its quantity is considerable. Therefore, phosphate recovery from municipal wastewater can bring many benefits such as relieving the burden of increasing production of fertilizers and reduction in occurrence of eutrophication caused by the excessive concentration of phosphate in the released effluent. The chemical processes are the most widely applied in phosphate recovery in municipal wastewater treatment because they are highly stable and efficient, and simple to operate. This paper compares chemical technologies for phosphate recovery from municipal wastewater. As phosphate in the influent is transferred to the liquid and sludge phases, a technical overview of chemical phosphate recovery in both phases is presented with reference to mechanism, efficiency and the main governing parameters. Moreover, an analysis on their applications at plant-scale is also presented. The properties of recovered phosphate and its impact on crops and plants are also assessed with a discussion on the economic feasibility of the technologies.
Young, C, Salunkhe, RR, Alshehri, SM, Ahamad, T, Huang, Z, Henzie, J & Yamauchi, Y 2017, 'High energy density supercapacitors composed of nickel cobalt oxide nanosheets on nanoporous carbon nanoarchitectures', Journal of Materials Chemistry A, vol. 5, no. 23, pp. 11834-11839.
View/Download from: Publisher's site
View description>>
This work demonstrates a simple approach to the development of NiCo2O4 and nanoporous carbon composites for high-performance supercapacitor application.
Yu, KL, Lau, BF, Show, PL, Ong, HC, Ling, TC, Chen, W-H, Ng, EP & Chang, J-S 2017, 'Recent developments on algal biochar production and characterization', Bioresource Technology, vol. 246, pp. 2-11.
View/Download from: Publisher's site
Yu, KL, Show, PL, Ong, HC, Ling, TC, Chi-Wei Lan, J, Chen, W-H & Chang, J-S 2017, 'Microalgae from wastewater treatment to biochar – Feedstock preparation and conversion technologies', Energy Conversion and Management, vol. 150, pp. 1-13.
View/Download from: Publisher's site
Yusoff, MNAM, Zulkifli, NWM, Masjuki, HH, Harith, MH, Syahir, AZ, Kalam, MA, Mansor, MF, Azham, A & Khuong, LS 2017, 'Performance and emission characteristics of a spark ignition engine fuelled with butanol isomer-gasoline blends', Transportation Research Part D: Transport and Environment, vol. 57, pp. 23-38.
View/Download from: Publisher's site
Zahid, R, Hassan, MBH, Varman, M, Mufti, RA, Kalam, MA, Zulkifli, NWBM & Gulzar, M 2017, 'A Review on Effects of Lubricant Formulations on Tribological Performance and Boundary Lubrication Mechanisms of Non-Doped DLC/DLC Contacts', Critical Reviews in Solid State and Materials Sciences, vol. 42, no. 4, pp. 267-294.
View/Download from: Publisher's site
Zare, M, Mohammady, M & Pradhan, B 2017, 'Modeling the effect of land use and climate change scenarios on future soil loss rate in Kasilian watershed of northern Iran', Environmental Earth Sciences, vol. 76, no. 8, pp. 1-15.
View/Download from: Publisher's site
View description>>
Accelerated erosion processes caused by global climate and land use changes in many regions of the world constitute a major restrictive factor in their sustainability. This study proposes a method to estimate soil loss rate under changes in future land use and climate in Kasilian watershed of northern Iran within two periods. The first period is related to current climate and land use (1991–2010), and the second concerns climate and land use scenarios (2011–2030). Downscaling global climate model projections of future climate was applied at the regional scale. A statistical downscaling model was then used to downscale precipitation for three scenarios, i.e., 10% increase in rainfall, 10% decrease in rainfall, and unchanged rainfall. Next, cellular automata–Markov model was used for characterization based on two scenarios of land use future that were designed using suitability maps. The soil loss mean for the current period was found to be 6.3 t ha−1year−1 , thereby indicating a low sustainability of soils. The results of simulated soil loss maps indicate a similar pattern in spatial distribution of loss rates compared with those of current periods, but the amount of risk has increased such that simulated erosion mean was 31–58% higher than the current period in all scenarios. Soil loss is thoroughly influenced by climate and land cover patterns in future. In other words, rainfall erosivity has increased by 20 MJ mm ha−1h−1year−1 , based on unchanged rainfall scenario and National Centers for Environmental Prediction data, simulated that cover management factor has increased by 35% compared with the current period. However, simulations indicated that land use changes may potentially induce much larger changes in erosion. The results also showed that soil loss is closely related to land use change and various scenarios of climate change and that revised universal soil loss equation is suitable model to investigate these relationships.
Zhang, B, Song, X, Nghiem, LD, Li, G & Luo, W 2017, 'Osmotic membrane bioreactors for wastewater reuse: Performance comparison between cellulose triacetate and polyamide thin film composite membranes', Journal of Membrane Science, vol. 539, pp. 383-391.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier B.V. This study compared the performance of the asymmetric cellulose triacetate (CTA) and polyamide thin film composite (TFC) forward osmosis (FO) membranes in an osmotic membrane bioreactor (OMBR). A reverse osmosis (RO) system was integrated with OMBR to regenerate the draw solution and produce clean water. Results show that the TFC membrane exhibited a higher initial water flux but more dramatic flux decline compared to the CTA membrane when they were used for OMBR. The CTA and TFC membranes also resulted in discernible difference in salinity build-up in the bioreactor and thus biomass characteristics during OMBR operation. All 30 trace organic contaminants (TrOCs) selected in this study were effectively removed by the OMBR-RO hybrid system regardless of the FO membrane type. Compared to the CTA membrane, the TFC membrane contributed more significantly toward the removal of hydrophilic and biologically persistent compounds and thus reduced their accumulation in the draw solution during OMBR-RO operation. In addition, CTA and TFC FO membranes also resulted in considerable differences in TrOC residuals in the sludge during OMBR operation.
Zhang, C, Guo, J, Lian, J, Lu, C, Ngo, HH, Guo, W, Song, Y & Guo, Y 2017, 'Characteristics of electron transport chain and affecting factors for thiosulfate-driven perchlorate reduction', Chemosphere, vol. 185, pp. 539-547.
View/Download from: Publisher's site
View description>>
The mechanism for perchlorate reduction was investigated using thiosulfate-driven (T-driven) perchlorate reduction bacteria. The influences of various environmental conditions on perchlorate reduction, including pH, temperature and electron acceptors were examined. The maximum perchlorate removal rate was observed at pH 7.5 and 40 °C. Perchlorate reduction was delayed due to the coexistence of perchlorate-chlorate and perchlorate-nitrate. The mechanism of the T-driven perchlorate reduction electron transport chain (ETC) was also investigated by utilizing different inhibitors. The results were as follows: firstly, the NADH dehydrogenase was not involved in the ETC; secondly, the FAD dehydrogenase and quinone loop participated in the ETC; and thirdly, cytochrome oxidase was the main pathway in the ETC. Meanwhile, microbial consortium structure analysis indicated that Sulfurovum which can oxidize sulfur compounds coupled to the reduction of nitrate or perchlorate was the primary bacterium in the T-driven and sulfur-driven consortium. This study generates a better understanding of the mechanism of T-driven perchlorate reduction.
Zhang, F, Wu, C, Zhao, X-L, Heidarpour, A & Li, Z 2017, 'Experimental and numerical study of blast resistance of square CFDST columns with steel-fibre reinforced concrete', Engineering Structures, vol. 149, pp. 50-63.
View/Download from: Publisher's site
View description>>
© 2016 Elsevier Ltd In recent years, a large number of studies have been carried out to investigate behaviours of concrete filled double skin steel tube (CFDST) members due to its increasing popularity in the construction industry. This paper firstly presents an experimental study on ultra-high performance concrete filled double-skin tubes subjected to close-range blast loading with cross section being square for both inner and outer steel tubes. It is evident that the proposed CFDST column was able to withstand a large blast load without failure so that it has the potential to be used in high-value buildings as well as critical infrastructures. Then, to further investigate the behaviours of the proposed CFDST column, a number of parametric studies were carried out by using a numerical model which was developed and calibrated based on the data acquired from the blast test along with some laboratory tests. Parameters that affect the behaviours of concrete filled double skin steel tube (CFDST) members against blasts are characterised.
Zhang, J, Sun, H, Wang, W, Hu, Z, Yin, X, Ngo, HH, Guo, W & Fan, J 2017, 'Enhancement of surface flow constructed wetlands performance at low temperature through seasonal plant collocation', Bioresource Technology, vol. 224, pp. 222-228.
View/Download from: Publisher's site
View description>>
In the present study, a novel seasonal plant collocation system (SPCS), specifically the Potamogeton crispus and Phragmites australis series system, was investigated to enhance the performance of surface flow constructed wetlands (SFCWs) at low temperature. Results of a year-round experiment showed that SPCS conquered the adverse effect of low temperature and achieved sustainable nutrients removal. In addition, during winter, removal efficiencies of NH4-N, TP, COD, and TN in SPCS were 18.1%, 17.6%, 10.1% and 5.2% higher than that in the control, respectively. P. crispus and P. australis complemented each other in terms of plant growth and plant uptake during the experiment period. Furthermore, it emerged that P. crispus could increase the quantity of ammonia oxidizing bacteria by 10.2%, due to its high oxygen enrichment ability. It is suggested that seasonal plant collocation has a promising future in SFCWs of areas being affected by climate change, e.g. northern China.
Zhang, S, Li, X, Teng, J, Ma, X & Sheng, D 2017, 'A theoretical method for determining sample mass in a sieving test', Computers and Geotechnics, vol. 91, pp. 12-16.
View/Download from: Publisher's site
Zhang, X, Sheng, D, Sloan, SW & Bleyer, J 2017, 'Lagrangian modelling of large deformation induced by progressive failure of sensitive clays with elastoviscoplasticity', International Journal for Numerical Methods in Engineering, vol. 112, no. 8, pp. 963-989.
View/Download from: Publisher's site
View description>>
SummaryThis paper presents a Lagrangian formulation of elastoviscoplasticity, on the basis of the particle finite element method, for progressive failure analysis of sensitive clays. The sensitive clay is represented by an elastoviscoplastic model that is a mixture of the Bingham model, for describing rheological behaviour, and the Tresca model with strain softening for capturing the progressive failure behaviour. The finite element formulation for the incremental elastoviscoplastic analysis is reformulated, through the application of the Hellinger–Reissner variational theorem, as an equivalent optimisation program that can be solved efficiently using modern algorithms such as the interior‐point method. The recast formulation is then incorporated into the framework of the particle finite element method for investigating progressive failure problems related to sensitive clays, such as the collapse of a sensitive clay column and the retrogressive failure of a slope in sensitive clays, where extremely large deformation occurs. Copyright © 2017 John Wiley & Sons, Ltd.
Zhang, X, Sloan, SW, Vignes, C & Sheng, D 2017, 'A modification of the phase-field model for mixed mode crack propagation in rock-like materials', Computer Methods in Applied Mechanics and Engineering, vol. 322, pp. 123-136.
View/Download from: Publisher's site
View description>>
The critical energy release rates for mode I and II fracture for rock-like materials are usually different. In this paper, a modified phase-field model is proposed for simulating mixed mode crack propagation. The model can distinguish between the critical energy release rates for mode I and mode II cracks. For the purpose of validation, rock-like materials with a single flaw or double flaws under compression are studied. The simulated results are compared to experimental data, both qualitatively and quantitatively. It is shown that the proposed model is able to capture the commonly observed propagation pattern of wing crack emergence followed by secondary cracks. Additionally, the typical types of crack coalescence observed in experimental tests are successfully reproduced, including the critical loads at which crack coalescence occurs.
Zhang, X, Song, Z, Guo, W, Lu, Y, Qi, L, Wen, H & Ngo, HH 2017, 'Behavior of nitrogen removal in an aerobic sponge based moving bed biofilm reactor', Bioresource Technology, vol. 245, no. PART A, pp. 1282-1285.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd This study aims to investigate the behavior of nitrogen removal in an aerobic sponge based moving bed biofilm reactor by evaluating nitrification and denitrification rates of sponge biocarriers from three aerobic moving bed biofilm reactors (MBBRs) with filling ratios of 10% (R-10), 20% (R-20) and 30% (R-30). Results showed that the highest removal efficiencies of total nitrogen in three reactors were 84.5% (R-10), 93.6% (R-20) and 95.3% (R-30). Correspondingly, simultaneous nitrification and denitrification rate (SND) was 90.9%, 97.6% and 100%, respectively. Although R-20 had the highest attached-growth biomass (AGB) per gram of sponge compared to the other two reactors, R-30 showed the maximum ammonium oxidation rate (AOR) (2.1826 ± 0.0717 mg NH 4 + -N/g AGB/h) and denitrification rate (DNR) (5.0852 ± 0.0891 mg NO 3 − -N/g AGB/h), followed by R-20 and R-10. These results indicated AOR, DNR and AGB were affected by the filling ratio under the same operation mode.
Zhang, X, Vignes, C, Sloan, SW & Sheng, D 2017, 'Numerical evaluation of the phase-field model for brittle fracture with emphasis on the length scale', Computational Mechanics, vol. 59, no. 5, pp. 737-752.
View/Download from: Publisher's site
View description>>
© 2017, Springer-Verlag Berlin Heidelberg. The phase-field model has been attracting considerable attention due to its capability of capturing complex crack propagations without mesh dependence. However, its validation studies have primarily focused on the ability to predict reasonable, sharply defined crack paths. Very limited works have so far been contributed to estimate its accuracy in predicting force responses, which is majorly attributed to the difficulty in the determination of the length scale. Indeed, accurate crack path simulation can be achieved by setting the length scale to be sufficiently small, whereas a very small length scale may lead to unrealistic force-displacement responses and overestimate critical structural loads. This paper aims to provide a critical numerical investigation of the accuracy of phase-field modelling of brittle fracture with special emphasis on a possible formula for the length scale estimation. Phase-field simulations of a number of classical fracture experiments for brittle fracture in concretes are performed with simulated results compared with experimental data qualitatively and quantitatively to achieve this goal. Furthermore, discussions are conducted with the aim to provide guidelines for the application of the phase-field model.
Zhang, Y, Huang, R, Xu, S, Huang, Y, Huang, S, Ma, Y & Wang, Z 2017, 'The effect of different n-butanol-fatty acid methyl esters (FAME) blends on puffing characteristics', Fuel, vol. 208, pp. 30-40.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The droplet suspension technology was used under the condition of atmospheric pressure and 873 K. The n-butanol concentration ranged from 0% to 75% to investigate the effect of n-butanol concentration on the puffing characteristics of a n-butanol-fatty acid methyl esters (FAME) droplet. Experimental results showed that BUT25, BUT50 and BUT75 (BUT'XX’ represented XX% n-butanol by mass fraction in the n-butanol-FAME blend) underwent three phases, namely the transient heating phase, fluctuation evaporation phase and equilibrium evaporation phase. The temperatures of BUT25, BUT50 and BUT75 were similar at the start and end of the transient heating phase. The duration of BUT75’s transient heating phase was much longer than that of BUT25 and BUT50. Therefore, the evaporation cooling of BUT75 was the most prominent because the temperature growth rate of BUT75 was significantly less than that of BUT25 and BUT50. Furthermore, the fluctuation evaporation phase could be divided into the strong and weak fluctuation stages. The violent fluctuation was only observed in the strong fluctuation stage. The weak fluctuation stage was similar as the stable evaporation. The active rupture was found in the strong fluctuation stage and the passive rupture was found in the weak fluctuation stage. The active and passive ruptures were caused by the fast bubble expansion and surface evaporation respectively. In addition, many periodic processes were contained in the strong fluctuation stage. The similarity degree of the periodic process showed a slump and a gradual increase, which were caused by bubble expansion and droplet recovery respectively. The bubble expansion of BUT50 was greater than that of BUT75. Significant bubble expansion led to the violent deformation after bubble rupture. The recovery time of BUT50 was longer than that of BUT75. Therefore, the similarity degree of BUT50 exhibited a wavy structure and BUT75 displayed a comb-like structure in the...
Zhang, Z, Song, X, Liu, Y, Wu, D & Song, C 2017, 'Three-dimensional mesoscale modelling of concrete composites by using random walking algorithm', Composites Science and Technology, vol. 149, pp. 235-245.
View/Download from: Publisher's site
View description>>
© 2017 Elsevier Ltd The mechanical performance of concrete is primarily dominated by the characteristics and interrelation of its ingredients, especially the content, shape and grading of coarse aggregates. Consequently, constructing a realistic mesostructure of concrete is essential for adequate mesoscale studies on the corresponding mechanical properties. In this study, a novel three-dimensional coarse aggregate generation scheme, namely the random walking algorithm (RWA), is proposed for constructing physically feasible mesostructures of concrete. The proposed approach is able to generate a series of aggregates within an initial placing domain, and subsequently, move them into the target domain by both translation and rotation. Within the proposed analysis framework, the high compactness of mesostructures with an improved aggregate content can be robustly achieved by randomly shifting previously placed aggregates, such that the later generated ones can be ingeniously blended in. Typical samples of random aggregate structure (RAS) are generated under specified grading curves. Parameters relating to aggregate content and efficiency of modelling are critically evaluated. By thoroughly investigating practically motivated examples, it is evidently illustrated that the present method is capable of obtaining a relatively realistic and random distribution of coarse aggregates, and more importantly, the grading of the generated aggregate samples is in compliance with the Fuller's Curve.
Zhao, H, Cao, Z, Liu, X, Zhan, Y, Zhang, J, Xiao, X, Yang, Y, Zhou, J & Xu, J 2017, 'Seasonal variation, flux estimation, and source analysis of dissolved emerging organic contaminants in the Yangtze Estuary, China', Marine Pollution Bulletin, vol. 125, no. 1-2, pp. 208-215.
View/Download from: Publisher's site
View description>>
The occurrence and seasonal variation of 24 dissolved emerging organic contaminants in the Yangtze Estuary were studied, including 12 non-antibiotic pharmaceuticals, seven sulfonamides, two macrolides and three chloramphenicols. Sulfadiazine, erythromycin, thiamphenicol and paracetamol were the primary contaminants in sulfonamides, macrolides, chloramphenicols and non-antibiotic pharmaceutical groups, respectively. Compared to the concentrations at Datong, chloramphenicols at Xuliujing were significantly higher in autumn and winter, while macrolides were lower in spring. Based on the flux estimation, approximately 37.1 tons of sulfonamides, 17.4 tons of macrolides, 79.2 tons of chloramphenicols and 14.1 tons of non-antibiotic pharmaceuticals were discharged into the Yangtze Estuary from June 2013 to May 2014. However, the total flux from the Huangpu River only represented 5% of the total. The pharmaceutical sources were speculated on by analyzing the seasonal variations in pharmaceutical concentrations and fluxes at various sites. Both environmental and social factors might affect the fluxes.
Zhao, J, Gui, L, Wang, Q, Liu, Y, Wang, D, Ni, B-J, Li, X, Xu, R, Zeng, G & Yang, Q 2017, 'Aged refuse enhances anaerobic digestion of waste activated sludge', Water Research, vol. 123, pp. 724-733.
View/Download from: Publisher's site
View description>>
In this work, a low-cost alternative approach (i.e., adding aged refuse (AR) into waste activated sludge) to significantly enhance anaerobic digestion of sludge was reported. Experimental results showed that with the addition dosage of AR increasing from 0 to 400 mg/g dry sludge soluble chemical oxygen demand (COD) increased from 1150 to 5240 mg/L at the digestion time of 5 d, while the maximal production of volatile fatty acids (VFA) increased from 82.6 to 183.9 mg COD/g volatile suspended solids. Although further increase of AR addition decreased the concentrations of both soluble COD and VFA, their contents in these systems with AR addition at any concentration investigated were still higher than those in the blank, which resulted in higher methane yields in these systems. Mechanism studies revealed that pertinent addition of AR promoted solubilization, hydrolysis, and acidogenesis processes and did not affect methanogenesis significantly. It was found that varieties of enzymes and anaerobes in AR were primary reason for the enhancement of anaerobic digestion. Humic substances in AR benefited hydrolysis and acidogenesis but inhibited methanogenesis. The effect of heavy metals in AR on sludge anaerobic digestion was dosage dependent. Sludge anaerobic digestion was enhanced by appropriate amounts of heavy metals but inhibited by excessive amounts of heavy metals. The relative abundances of microorganisms responsible for sludge hydrolysis and acidogenesis were also observed to be improved in the system with AR addition, which was consistent with the performance of anaerobic digestion.
Zhao, Y, Phuntsho, S, Gao, B & Shon, H 2017, 'Polytitanium sulfate (PTS): Coagulation application and Ti species detection', Journal of Environmental Sciences, vol. 52, pp. 250-258.
View/Download from: Publisher's site
View description>>
© 2016 Interest in the development of inorganic polymerized coagulants is growing; however, there are only limited studies on the synthesis of polytitanium coagulants, which are expected to exhibit improved coagulation efficiency with better floc properties. This study presents the synthesis of polytitanium sulfate (PTS) for potential application in water purification, followed by characterization of PTS flocs and titanium species detection. Stable PTS solutions were successfully synthesized and standard jar tests were conducted to evaluate their coagulation efficiency. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) speciation analysis revealed that a variety of mononuclear and polynuclear complexes were formed in PTS solution, indicating the polymeric nature of the synthesized coagulant. Floc characteristics were studied through on-line monitoring of floc size using a laser diffraction particle size analyzer. Results showed that PTS had a comparable or in some cases even higher organic matter and particulate removal efficiency than Ti(SO4)2. The effluent pH after PTS coagulation significantly improved toward desirable values closer to neutral pH. Properties of flocs formed by PTS were significantly improved in terms of floc size, growth rate and structure. This study showed that PTS could be an efficient and promising coagulant for water purification, with the additional benefit that its coagulated sludge can be used to recover valuable TiO2 nanoparticles for various commercial applications.
Zhao, Y, Sun, Y, Tian, C, Gao, B, Wang, Y, Shon, H & Yang, Y 2017, 'Titanium tetrachloride for silver nanoparticle-humic acid composite contaminant removal in coagulation-ultrafiltration hybrid process: floc property and membrane fouling', Environmental Science and Pollution Research, vol. 24, no. 2, pp. 1757-1768.
View/Download from: Publisher's site
View description>>
© 2016, Springer-Verlag Berlin Heidelberg. Titanium-based coagulation is expected to achieve both efficient water purification and sludge recycling. This study is the first attempt to use titanium tetrachloride (TiCl4) for silver nanoparticle (AgNP)-humic acid composite contaminant removal in a coagulation-ultrafiltration (C-UF) process, where characterization of flocs and membrane fouling under varied coagulant dose, initial solution pH, and AgNP concentration conditions are the main contents. Results suggested that the TiCl4 achieved high AgNP removal in the form of silver nanoparticle through adsorption and sweep flocculation and simultaneously exerted additional 68.2 % higher dissolved organic carbon removal than Al2(SO4)3. The TiCl4 produced larger and stronger flocs but with weaker recoverability and less compact degree than did Al2(SO4)3. Floc properties were independent of AgNP concentration except floc fractal dimension, which was negatively correlated with AgNP concentration. The TiCl4 precoagulation caused less membrane fouling within wider pH range than Al2(SO4)3 did in the C-UF process. Incorporation of AgNPs during the TiCl4 pretreatment process facilitated the mitigation of membrane fouling, which was, however, negligibly influenced by AgNP concentration in the case of Al2(SO4)3.
Zheng, G, Fang, G, Shankaran, R, Orgun, MA, Zhou, J, Qiao, L & Saleem, K 2017, 'Multiple ECG Fiducial Points-Based Random Binary Sequence Generation for Securing Wireless Body Area Networks', IEEE Journal of Biomedical and Health Informatics, vol. 21, no. 3, pp. 655-663.
View/Download from: Publisher's site
View description>>
© 2017 IEEE. Generating random binary sequences (BSes) is a fundamental requirement in cryptography. A BS is a sequence of $N$ bits, each bit has a value of 0 or 1. For securing sensors within wireless body area networks (WBANs), electrocardiogram (ECG)-based BS generation methods have been widely investigated in which interpulse intervals (IPIs) from each heartbeat cycle are processed to produce BSes. Using these IPI-based methods to generate a 128-bit BS in real time normally takes around half a minute. In order to improve the time efficiency of such methods, this paper presents an ECG multiple fiducial-points based binary sequence generation (MFBSG) algorithm. The technique of discrete wavelet transforms is employed to detect arrival time of these fiducial points, such as P, Q, R, S, T peaks. Time intervals between them, including RR, RQ, RS, RP, RT intervals, are then calculated based on this arrival time, are used as ECG features to generate random BSes with low latency. According to our analysis on real ECG data, these ECG feature values exhibit the property of randomness and, thus, can be utilized to generate random BSes. Compared with the schemes that solely rely on IPIs to generate BSes, this MFBSG algorithm uses five feature values from one heart beat cycle, can be up to five times faster than the solely IPI-based methods. So, it achieves a design goal of low latency. According to our analysis, the complexity of the algorithm is comparable to that of fast Fourier transforms. These randomly generated ECG BSes can be used as security keys for encryption or authentication in a WBAN system.
Zheng, J, Li, Y & Wang, J 2017, 'Design and multi-physics optimization of a novel magnetorheological damper with a variable resistance gap', Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, vol. 231, no. 17, pp. 3152-3168.
View/Download from: Publisher's site
View description>>
This paper presents the design and multi-physics optimization of a novel multi-coil magnetorheological (MR) damper with a variable resistance gap (VRG-MMD). Enabling four electromagnetic coils (EMs) with individual exciting currents, a simplified magnetic equivalent circuit was presented and the magnetic flux generated by each voltage source passing through each active gap was calculated as vector operations. To design the optimal geometry of the VRG-MMD, the multi-physics optimization problem including electromagnetics and fluid dynamics has been formulated as a multi-objective function with weighting ratios among total damping force, dynamic range, and inductive time constant. Based on the selected design variables (DVs), six cases with different weighting ratios were optimized using Bound Optimization BY Quadratic Approximation (BOBYQA) technique. Finally, the vibration performance of the optimal VRG-MMD subjected to sinusoidal and triangle displacement excitations was compared to that of the typical multi-coil MR damper.
Zhi, XD & Stewart, MG 2017, 'Damage and Risk Assessment for Single-Layer Reticulated Domes Subject to Explosive Blast Loads', International Journal of Structural Stability and Dynamics, vol. 17, no. 09, pp. 1750108-1750108.
View/Download from: Publisher's site
View description>>
In order to provide a better understanding of the dynamic behavior of single-layer reticulated domes subjected to explosive blast loads, a number of analyses are carried out on structures with different standoff distances ([Formula: see text]), explosive weights ([Formula: see text]), rise–span ratios ([Formula: see text] and other parameters. An equation for a structural damage factor is proposed to evaluate structural damage quantitatively. The damage states for single-layer reticulated domes are defined based on their structural dynamic performance and corresponding damage factors. Structural reliabilities for different standoff distances are obtained using the Monte-Carlo Analysis. A typical protective measure is bollards which are used to help ensure a minimum standoff distance. To illustrate the cost-effectiveness of such a protective measure, structural damage states and various losses, including direct and indirect economic loss and maimed and fatality loss, are considered for assessing the risk reduction, costs and benefits. It was found that the bollards significantly reduce the likelihood of structural progressive collapse or severe damage, and the optimal standoff distance can be determined.
Zhou, X, Chen, H, Gao, S-H, Han, S, Tu, R, Wei, W, Cai, C, Liu, P, Jin, W & Wang, Q 2017, 'Effects of particle size of zero-valent iron (ZVI) on peroxydisulfate-ZVI enhanced sludge dewaterability', Korean Journal of Chemical Engineering, vol. 34, no. 10, pp. 2672-2677.
View/Download from: Publisher's site
View description>>
The advanced oxidization process has proven to be an effective conditioning technique for the improvement of sludge dewaterability. Zero-valent iron (ZVI) is often used as the catalyst of the oxidization process. This study applied ZVI with different particle sizes to the ZVI- peroxydisulfate reactions, and investigated their effects on the improvement of sludge dewaterability. It was found that ZVI particles with smaller sizes (100 and 400 meshes) led to slightly higher enhancement of sludge dewaterability (69.1%–72%) than the larger size particles (20–40 meshes) with the reduction rate of CST by 64%. However, after the treatment, the recycle rate of larger size ZVI particles was obviously higher than the small sizes ZVI particles: 98.3% vs. 87.6–89.7%. Different surface areas of the ZVI particles with different sizes might contribute to the phenomenon. For the small ZVI particles with the sizes of 100 and 400 meshes, no obvious differences of oxidization effects and the improvements of sludge dewaterability were found between them, which might be because an oxide layer could have been formed on the surface of fine ZVI particles and led to agglomeration. According to the economical analysis, the small particles (100 and 400 meshes) of ZVI were more economically favorable for the oxidative conditioning process with ZVI-peroxydisulfate than large ZVI particles (20–40 meshes).
Zhou, X, Jin, W, Chen, H, Chen, C, Han, S, Tu, R, Wei, W, Gao, S-H, Xie, G-J & Wang, Q 2017, 'Enhancing dewaterability of waste activated sludge by combined oxidative conditioning process with zero-valent iron and peroxymonosulfate', Water Science and Technology, vol. 76, no. 9, pp. 2427-2433.
View/Download from: Publisher's site
View description>>
Abstract The enhancement of sludge dewaterability is of great importance for facilitating the sludge disposal during the operation of wastewater treatment plants. In this study, a novel oxidative conditioning approach was applied to enhance the dewaterability of waste activated sludge by the combination of zero-valent iron (ZVI) and peroxymonosulfate (PMS). It was found that the dewaterability of sludge was significantly improved after the addition of ZVI (0–4 g/g TSS) (TSS: total suspended solids) and PMS (0–1 g/g TSS). The optimal addition amount of ZVI and PMS was 0.25 g/g TSS and 0.1 g/g TSS, respectively, under which the capillary suction time of the sludge was reduced by approximately 50%. The decomposition of sludge flocs could contribute to the improved sludge dewaterability. Economic analysis demonstrated that the proposed conditioning process with ZVI and PMS was more economical than the ZVI + peroxydisulfate and the traditional Fenton conditioning processes.
Zuthi, MFR, Guo, W, Ngo, HH, Nghiem, DL, Hai, FI, Xia, S, Li, J, Li, J & Liu, Y 2017, 'New and practical mathematical model of membrane fouling in an aerobic submerged membrane bioreactor', Bioresource Technology, vol. 238, pp. 86-94.
View/Download from: Publisher's site
View description>>
This study aimed to develop a practical semi-empirical mathematical model of membrane fouling that accounts for cake formation on the membrane and its pore blocking as the major processes of membrane fouling. In the developed model, the concentration of mixed liquor suspended solid is used as a lumped parameter to describe the formation of cake layer including the biofilm. The new model considers the combined effect of aeration and backwash on the foulants' detachment from the membrane. New exponential coefficients are also included in the model to describe the exponential increase of transmembrane pressure that typically occurs after the initial stage of an MBR operation. The model was validated using experimental data obtained from a lab-scale aerobic sponge-submerged membrane bioreactor (MBR), and the simulation of the model agreed well with the experimental findings.
