Abdullahi, S, Mahmud, ARB & Pradhan, B 2014, 'Spatial modelling of site suitability assessment for hospitals using geographical information system-based multicriteria approach at Qazvin city, Iran', Geocarto International, vol. 29, no. 2, pp. 164-184.
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Alamdari, MM, Li, J, Samali, B, Ahmadian, H & Naghavi, A 2014, 'Nonlinear Joint Model Updating in Assembled Structures', Journal of Engineering Mechanics, vol. 140, no. 7, pp. 04014042-04014042.
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Dynamic response of mechanical structures is significantly affected by joints. Joints introduce remarkable frictional damping and
localized flexibility to the structure; hence, to obtain a more accurate representation of a system’s dynamics, it is crucial to take these effects into
account. This paper investigates the application of finite-element model updating on characterization of a nonlinear joint interface. A thin layer
of virtual elements is used at a joint location to represent the nonlinear behavior of the coupling in the tangential direction. The material
properties of the elements are described by a nonlinear constitutive stress-strain equation that defines the nonlinear state of the joint interface. In
this study, Richard–Abbot elastic-plastic material was considered, which is capable of characterizing energy dissipation and softening
phenomena in a joint at a nonlinear state. Uncertain material parameters are adjusted to minimize the residual between the numerical and
experimental nonlinear frequency responses. Minimization was carried out based on iterative sensitivity-based optimization. The procedure was
implemented on an assembled structure consisting of two steel threaded pipes coupled to each other by a nut interface. It was demonstrated that
the proposed technique significantly reduced the uncertainties in the joint modeling and led to a more reliable description of the assembled
structure.
Alsharif, AAA & Pradhan, B 2014, 'Urban Sprawl Analysis of Tripoli Metropolitan City (Libya) Using Remote Sensing Data and Multivariate Logistic Regression Model', Journal of the Indian Society of Remote Sensing, vol. 42, no. 1, pp. 149-163.
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Al-sharif, AAA & Pradhan, B 2014, 'Monitoring and predicting land use change in Tripoli Metropolitan City using an integrated Markov chain and cellular automata models in GIS', Arabian Journal of Geosciences, vol. 7, no. 10, pp. 4291-4301.
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Althuwaynee, OF, Pradhan, B, Park, H-J & Lee, JH 2014, 'A novel ensemble bivariate statistical evidential belief function with knowledge-based analytical hierarchy process and multivariate statistical logistic regression for landslide susceptibility mapping', CATENA, vol. 114, pp. 21-36.
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Althuwaynee, OF, Pradhan, B, Park, H-J & Lee, JH 2014, 'A novel ensemble decision tree-based CHi-squared Automatic Interaction Detection (CHAID) and multivariate logistic regression models in landslide susceptibility mapping', Landslides, vol. 11, no. 6, pp. 1063-1078.
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Amani, A, Mansor, S, Pradhan, B, Billa, L & Pirasteh, S 2014, 'Coupling effect of ozone column and atmospheric infrared sounder data reveal evidence of earthquake precursor phenomena of Bam earthquake, Iran', Arabian Journal of Geosciences, vol. 7, no. 4, pp. 1517-1527.
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Amiri, F, bin Mohamed Shariff, AR, Tabatabaie, T & Pradhan, B 2014, 'A geospatial model for the optimization grazing management in semi-arid rangeland of Iran', Arabian Journal of Geosciences, vol. 7, no. 3, pp. 1101-1114.
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Amiri, F, Rahdari, V, maleki najafabadi, S, Pradhan, B & Tabatabaei, T 2014, 'Erratum to: Multi-temporal landsat images based on eco-environmental change analysis in and around Chah Nimeh reservoir, Sistan and Balochestan (Iran)', Environmental Earth Sciences, vol. 72, no. 3, pp. 811-811.
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Amiri, F, Rahdari, V, maleki najafabadi, S, Pradhan, B & Tabatabaei, T 2014, 'Multi-temporal landsat images based on eco-environmental change analysis in and around Chah Nimeh reservoir, Balochestan (Iran)', Environmental Earth Sciences, vol. 72, no. 3, pp. 801-809.
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Amiri, F, Rahdari, V, Pradhan, B & Tabatabaei, T 2014, 'Multi-temporal landsat images based on eco-environmental change analysis in and around Chah Nimeh reservoir, Balochestan (Iran)', Environmental earth sciences, vol. 72, no. 3, pp. 801-809.
Ansari, Y, Kouretzis, GP & Sheng, D 2014, 'An effective stress analysis of partially embedded offshore pipelines: Vertical penetration and axial walking', Computers and Geotechnics, vol. 58, pp. 69-80.
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Ansari, Y, Merifield, R & Sheng, D 2014, 'A piezocone dissipation test interpretation method for hydraulic conductivity of soft clays', Soils and Foundations, vol. 54, no. 6, pp. 1104-1116.
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Ansari, Y, Pineda, J, Kouretzis, G & Sheng, D 2014, 'Experimental and numerical investigation of rate and softening effects on the undrained shear strength of ballinaclay', Australian Geomechanics Journal, vol. 49, no. 4, pp. 51-57.
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We present the basic components of a methodology to investigate two key aspects of the mechanical behaviour of some natural clays, namely the dependency of the undrained shear strength on the rate of shearing, and the softening response at large strains. For that, we will use a blend of novel experimental testing procedures and cutting-edge computational techniques, currently under development at the University of Newcastle. Measurements of the shear stress-strain response under undrained conditions will be obtained using a newly developed miniature vane shear apparatus, featuring automatic control of the blade rotation velocity. Laboratory tests will be complemented with largedeformation numerical simulations of the vane test with the coupled Eulerian-Lagrangian method. For that, an appropriate constitutive model is implemented in ABAQUS/Explicit, able to simulate the visco-plastic strain-softening response of soft clays. Testing will be performed on the soft estuarine clay samples retrieved from the national geotechnical soft soil field testing facility, established in Ballina, NSW. With the focus being on Australian soft clays, the long-term goal of this study is to improve the procedures for performing and interpreting in situ tests included in Australian Standards.
Banwell, GH, Roberts, JR, Halkon, BJ, Rothberg, SJ & Mohr, S 2014, 'Understanding the Dynamic Behaviour of a Tennis Racket under Play Conditions', Experimental Mechanics, vol. 54, no. 4, pp. 527-537.
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The 'feel' of tennis rackets is of increasing importance to manufacturers seeking product differentiation in a context where further performance enhancements are prevented by a combination of mechanical limits and regulations imposed to protect the integrity of the sport. Vibrations excited during a shot contribute greatly to the perception of 'feel'. Previous studies have been reported but none has covered the full set of mode families or the frequency range in this study. In-plane vibrations associated with the routine use of topspin shots in modern tennis have not been documented so far in the literature. To consider modal behaviour, multiple measurements during play conditions are required but this is practically impossible. This paper proposes an alternative approach and successfully relates a comprehensive modal analysis on a freely suspended racket to vibration measurements under play conditions. This is achieved through an intermediate stage comprising a necessarily more limited modal analysis on a hand-gripped racket and use of the mass modification modal analysis tool. This stage confirmed the prevailing view that hand-gripping can be considered as a mass modification distributed along the handle of the freely suspended racket but the associated mass was much lower than that of an actual hand and the hand also increased the damping ratio of frame modes significantly. Furthermore, in frame vibration measurements during forehand groundstrokes, a greater reduction in bending mode frequencies was observed, consistent with a mass-loading of around 25 % of the actual hand as a consequence of the tighter grip. In these play tests, the first two bending modes, the first torsional mode, the first eight stringbed modes, the first three hoop modes and the third in-plane bending mode were identified, with the stringbed modes being particularly prominent. © 2013 Society for Experimental Mechanics.
Billa, L, Pradhan, B & Yakuup, A 2014, 'GIS routing and modelling of residential waste collection for operational management and cost optimization', Pertanika Journal of Science and Technology, vol. 22, no. 1, pp. 193-212.
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In this paper, optimum routing was developed based on the travel salesman method and integrated in ArcInfo GIS using linear programming. The results of the optimized travel distances and times for residential waste collection and routing to disposal site were used to calculate the number and type of required track collection, labour requirement, costing of waste collection and to determine the overall solid waste management efficiency through waste management operation research methods. The objective of the study was to optimize residential collection and hauling to disposal site through operation cost minimization for Petaling Jaya Municipality in the state of Selangor, Malaysia. The study determined that with optimized routes and recycling possibilities, the total cost of waste collections could be reduced from RM90,372 to RM20,967, with a reduction of 76.8%. It was also revealed that optimum routes might not necessarily be the shortest distance from point A to point B as travel time maybe high on short distances due to traffic congestion and the presence of many traffic lights. Techniques and methods developed using general GIS have proven effective in route optimization and allowed management of data to suit local conditions and limitations of waste management for the studied area. Thus, scenarios of travel distances, time and waste quantity value generated from the GIS enabled appropriate determination of the number of waste trucks and labour requirements for the operation and the overall calculation of costs of waste management based on the operation research methods used in the study.
Bu, G, Lee, J, Guan, H, Blumenstein, M & Loo, Y-C 2014, 'Development of an Integrated Method for Probabilistic Bridge-Deterioration Modeling', Journal of Performance of Constructed Facilities, vol. 28, no. 2, pp. 330-340.
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Probabilistic deterioration models such as state-based and time-based models are only capable of predicting future bridge-condition ratings when a sufficient amount of condition data and reasonable data distribution are available. However, such are usually difficult to acquire from limited bridge-inspection records. As a result, these probabilistic models cannot guarantee reliable long-term prediction for each of the bridge elements concerned. To minimize this shortcoming, this paper proposes an advanced integrated method to construct workable transition probabilities for predicting long-term bridge performance. A selection process within this method automatically chooses a suitable prediction procedure for a given situation in terms of available inspection data. The backward prediction model (BPM) is also incorporated to effectively predict the bridge performance when sufficient inspection data are unavailable. Four different situations in regard to the available inspection data are predefined in this study to demonstrate the capabilities of the proposed integrated method. The outcomes show that the method can help develop an effective prediction model for various situations in terms of the quantity and distribution of available condition-rating data. © 2014 American Society of Civil Engineers.
Bu, GP, Lee, JH, Guan, H, Loo, YC & Blumenstein, M 2014, 'Implementation of Elman neural networks for enhancing reliability of integrated bridge deterioration model', Australian Journal of Structural Engineering, vol. 15, no. 1, pp. 51-63.
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Probabilistic modelling is one of the most prominent techniques in bridge deterioration forecast. It can be classified into two types, namely, state- and time-based models. Reliability of both modelling techniques in forecasting long-term performance rely heavily on sufficient amount of bridge condition rating data being available together with well-distributed deterioration pattern over the age of bridge. However, it can be problematic when the available condition rating records are insufficient. In order to overcome this problem, an integrated deterioration method incorporating both the state- and time-based models has recently been developed. Despite such development and advancement, certain issues still remain with some cases of given condition data that cannot be used to produce reliable long-term performance curve. Aiming to achieve enhanced prediction performance, an Elman neural networks (ENN) technique is incorporated in the integrated method to replace the third-order polynomial regression function, the latter being the core component for long-term prediction in the state-based model. In the present study, the ENN are able to generate more reliable deterioration patterns than a typical deterministic method. The results demonstrate that the integrated method incorporating ENN are more effective in handling various situations of condition data quantities and distributions for generating long-term performance curves. © Institution of Engineers Australia, 2014.
Bui, DT, Pradhan, B & Revhaug, I 2014, 'and Chuyen Trung Tran', Remote Sensing Applications in Environmental Research, p. 87.
Burton, GJ, Sheng, D & Airey, D 2014, 'Experimental study on volumetric behaviour of Maryland clay and the role of degree of saturation', Canadian Geotechnical Journal, vol. 51, no. 12, pp. 1449-1455.
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In this paper, the volume change behaviour of Maryland clay compacted on the wet side of standard Proctor optimum water content (with lower compaction energy) is studied in reference to the saturated reconstituted state. Oedometer tests over a range of suctions and vertical stresses have been carried out, and the results have shown that the compression index reaches a peak (approximately twice that of the reconstituted material) and then gradually reduces to the reconstituted value as the stress level is increased. The results are analyzed in a framework where the degree of saturation is treated as a state parameter and controls the slope of the unsaturated normal compression line. Tests conducted under constant suction and constant water content have been used to demonstrate the effectiveness of using the degree of saturation as a state variable.
Burton, GJ, Sheng, D & Campbell, C 2014, 'Bimodal pore size distribution of a high-plasticity compacted clay', Géotechnique Letters, vol. 4, no. 2, pp. 88-93.
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The microstructure of compacted clay plays an important role in its hydraulic and mechanical behaviour. However, little experimental evidence is available for high-plasticity clay compacted on the wet side of the standard Proctor optimum water content. The results of an oedometric and microstructural investigation (mercury intrusion porosimetry) on reconstituted and compacted high-plasticity clay are presented. The microstructural results indicate that a bimodal pore size density function is not limited to clays compacted on the dry side of the standard Proctor optimum. The compacted clay prepared on the wet side can display a bimodal pore size distribution dependent on the level of compaction, current void ratio and degree of saturation. The bimodal distribution of the compacted clay can be lost by compression to high vertical stress accompanied by an increase in the degree of saturation. In this case the compression path ultimately approaches the normal compression line of the reconstituted saturated material. The results demonstrate that the observed behaviour of the compacted clay can be interpreted with reference to the reconstituted clay.
Cai, G, Zhou, A & Sheng, D 2014, 'Permeability function for unsaturated soils with different initial densities', Canadian Geotechnical Journal, vol. 51, no. 12, pp. 1456-1467.
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This study proposes an approach to simulate the effects of initial density on the relative coefficient of permeability for unsaturated soils. The density-dependent permeability function is derived based on (i) an incremental relationship between the degree of saturation and the initial void ratio with various suctions and (ii) the relationship between the permeability function and the soil-water retention curve (SWRC). Only one additional parameter is required in the proposed function, which can be calibrated using a conventional SWRC test. A number of test results in the literature are employed to validate the proposed density-dependent permeability function, and the model predictions indicate good agreement with the experimental data in the literature.
Cai, GQ, Sheng, DC & Zhou, AN 2014, 'Approach for predicting the relative coefficient of permeability of unsaturated soils with different initial void ratios', Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering, vol. 36, no. 5, pp. 827-835.
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A simple approach is proposed to quantify the effect of the initial void ratio on the relative coefficient of permeability for unsaturated soils based on the incremental relationship between the degree of saturation and the initial void ratio and the prediction of the permeability function for unsaturated soils by use of the soil-water characteristic curve (SWCC). For a given soil and the SWCC equation, only one additional parameter is introduced, which can be conveniently calibrated by the conventional SWCC tests. The relative coefficient of permeability for the same soil with different initial void ratios can be predicted by this approach. The proposed approach is validated through experimental data from the literatures in which both the SWCCs and the coefficients of permeability with different initial void ratios are measured.
Cai, G-Q, Zhao, C-G, Sheng, D-C & Zhou, A-N 2014, 'Formulation of thermo-hydro-mechanical coupling behavior of unsaturated soils based on hybrid mixture theory', Acta Mechanica Sinica, vol. 30, no. 4, pp. 559-568.
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Cassidy, MJ, Gaudin, C, Bates, L, Indraratna, B, Nimbalkar, S, O'Loughlin, CD, White, DJ & Sloan, SW 2014, 'Advancing Australia's facilities for physical modelling in geotechnics', Australian Geomechanics Journal, vol. 49, no. 4, pp. 3-12.
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This paper presents details of the advancements of the Australian Research Council Centre of Excellence for Geotechnical Science and Engineering to the apparatus, facilities and methods for physical modelling in geotechnics. This advancement includes (i) the launch of a National Geotechnical Centrifuge Facility with a new 10 m diameter fixed beam centrifuge that will be capable of spinning 2.4 tonnes of soil at 100 gravities, (ii) a new mobile soft soil in situ testing laboratory, (iii) a new national facility for the cyclic testing of high-speed rail and (iv) three recirculating flumes, called O-tubes, which are presented in another paper of this special issue. This paper provides an overview of this new equipment and the aims of the research that it will underpin. The equipment will provide enhanced possibilities for Australia to conduct project specific testing for future energy and transportation infrastructure developments, nationally and internationally.
Chen, Q, Indraratna, B, Carter, J & Rujikiatkamjorn, C 2014, 'A theoretical and experimental study on the behaviour of lignosulfonate-treated sandy silt', Computers and Geotechnics, vol. 61, pp. 316-327.
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Chu, J, Indraratna, B, Yan, S & Rujikiatkamjorn, C 2014, 'Overview of preloading methods for soil improvement', Proceedings of the Institution of Civil Engineers - Ground Improvement, vol. 167, no. 3, pp. 173-185.
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A review of the recent developments in soft soil improvement through consolidation or preloading is presented in this paper. The topics covered range from fundamental analysis to methods of implementation. Various methods and processes related to vertical drains, vacuum preloading or combined vacuum and fill surcharge, and dynamic consolidation with enhanced drainage or vacuum are compared and discussed. Factors affecting the design and analyses for the methods discussed are also elaborated.
Dadras, M, Mohd Shafri, HZ, Ahmad, N, Pradhan, B & Safarpour, S 2014, 'A COMBINED FUZZY MCDM APPROACH FOR IDENTIFYING THE SUITABLE LANDS FOR URBAN DEVELOPMENT: AN EXAMPLE FROM BANDAR ABBAS, IRAN', Journal of Urban and Environmental Engineering, vol. 8, no. 1, pp. 11-27.
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This study aims at identifying the suitable lands for urban development in Bandar Abbas city based on its real world use regarding specific criteria and sub-criteria. The city of Bandar Abbas is considered as the most important commercial and economic city of Iran. It is also considered as one of the major cities of Iran which has played a pivotal role in the country's development and progress in recent years especially after the end of Iran-Iraq war owing to its embracing the country's main commercial ports. This process has caused the immigration rate into the city to rise significantly over the past 20 years. Thus, the development of the city is meanwhile considered as a high priority. Bandar Abbas city does not have a rich capacity for growth and development due to its special geographical situation being located in coastal border. Among the limitations placed in the city's development way, natural limitations (heights and sea shore) in the northern and southern parts of the city and structural limitations (military centers) in the east and west sides of the city may be referred. Therefore, identifying the suitable lands for urban development within Bandar Abbas city limits is becoming an essential priority. Therefore, different quantitative and qualitative criteria have been studied in order to select and identify these lands. The structures of qualitative criteria for most parts involve ambiguities and vagueness. This leads us to use Fuzzy logic in this study as a natural method for determining the solutions for problems of Multi-criteria decision making (MCDM). In the current research, a combination of MCDM methods has been presented for analysis. To assignee weights of the criteria Fuzzy AHP (analytic hierarchy process) is used for land selection and Fuzzy TOPSIS (method for order priority by similarity to ideal solution) is utilized to choose the alternative that is the most appropriate through these criteria weights. The sensitivity an...
Dadras, M, Mohd Shafri, HZ, Ahmad, N, Pradhan, B & Safarpour, S 2014, 'A COMBINED FUZZY MCDM APPROACH FOR IDENTIFYING THE SUITABLE LANDS FOR URBAN DEVELOPMENT: AN EXAMPLE FROM BANDAR ABBAS, IRAN', Journal of Urban and Environmental Engineering, vol. 8, no. 1, pp. 11-27.
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This study aims at identifying the suitable lands for urban development in Bandar Abbas city based on its real world use regarding specific criteria and sub-criteria. The city of Bandar Abbas is considered as the most important commercial and economic city of Iran. It is also considered as one of the major cities of Iran which has played a pivotal role in the country's development and progress in recent years especially after the end of Iran-Iraq war owing to its embracing the country's main commercial ports. This process has caused the immigration rate into the city to rise significantly over the past 20 years. Thus, the development of the city is meanwhile considered as a high priority. Bandar Abbas city does not have a rich capacity for growth and development due to its special geographical situation being located in coastal border. Among the limitations placed in the city's development way, natural limitations (heights and sea shore) in the northern and southern parts of the city and structural limitations (military centers) in the east and west sides of the city may be referred. Therefore, identifying the suitable lands for urban development within Bandar Abbas city limits is becoming an essential priority. Therefore, different quantitative and qualitative criteria have been studied in order to select and identify these lands. The structures of qualitative criteria for most parts involve ambiguities and vagueness. This leads us to use Fuzzy logic in this study as a natural method for determining the solutions for problems of Multi-criteria decision making (MCDM). In the current research, a combination of MCDM methods has been presented for analysis. To assignee weights of the criteria Fuzzy AHP (analytic hierarchy process) is used for land selection and Fuzzy TOPSIS (method for order priority by similarity to ideal solution) is utilized to choose the alternative that is the most appropriate through these criteria weights. The sensitivity an...
Dadras, M, Mohd Shafri, HZ, Ahmad, N, Pradhan, B & Safarpour, S 2014, 'Land Use/Cover Change Detection and Urban Sprawl Analysis in Bandar Abbas City, Iran', The Scientific World Journal, vol. 2014, pp. 1-12.
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The process of land use change and urban sprawl has been considered as a prominent characteristic of urban development. This study aims to investigate urban growth process in Bandar Abbas city, Iran, focusing on urban sprawl and land use change during 1956–2012. To calculate urban sprawl and land use changes, aerial photos and satellite images are utilized in different time spans. The results demonstrate that urban region area has changed from 403.77 to 4959.59 hectares between 1956 and 2012. Moreover, the population has increased more than 30 times in last six decades. The major part of population growth is related to migration from other parts the country to Bandar Abbas city. Considering the speed of urban sprawl growth rate, the scale and the role of the city have changed from medium and regional to large scale and transregional. Due to natural and structural limitations, more than 80% of barren lands, stone cliffs, beach zone, and agricultural lands are occupied by built-up areas. Our results revealed that the irregular expansion of Bandar Abbas city must be controlled so that sustainable development could be achieved.
Diyaljee, V 2014, 'Discussion of “Deformation of Coal Fouled Ballast Stabilized with Geogrid under Cyclic Load” by Buddhima Indraratna, Ngoc Trung Ngo, and Cholachat Rujikiatkamjorn', Journal of Geotechnical and Geoenvironmental Engineering, vol. 140, no. 6, pp. 07014010-07014010.
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Elbialy, S, Mahmoud, A, Pradhan, B & Buchroithner, M 2014, 'Application of spaceborne synthetic aperture radar data for extraction of soil moisture and its use in hydrological modelling at Gottleuba Catchment, Saxony, Germany', Journal of Flood Risk Management, vol. 7, no. 2, pp. 159-175.
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AbstractHydrological modelling is a powerful tool for hydrologists and engineers involved in the planning and management of water resources. With the recent advent of computational power and the growing availability of spatial data, remote sensing and geographical information systems technologies can augment to a great extent the conventional methods used in rainfall run‐off studies. That means it is possible to accurately describe the characteristics of watershed in particularly when determining the run‐off response to rainfall inputs. The main objective of this study is to apply the potential application of spaceborne synthetic aperture radar (SAR) data (i.e. TerraSAR‐X and Advanced Land Observing Satellite/Phased Array type L‐band Synthetic Aperture Radar (ALOS PALSAR) for soil moisture retrieval) and to improve the spatial input parameters required for hydrological modelling. For the spatial database creation, a high‐resolution 2‐m aerial laser scanning digital terrain model, soil map, and land use map were used. Rainfall records were transformed into a run‐off through hydrological parameterisation of the watershed using Hydro...
Fatahi, B & Tabatabaiefar, SHR 2014, 'Effects of Soil Plasticity on Seismic Performance of Mid-Rise Building Frames Resting on Soft Soils', Advances in Structural Engineering, vol. 17, no. 10, pp. 1387-1402.
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In this study, the effects of Plasticity Index (PI) variation on the seismic response of mid-rise building frames resting on soft soil deposits are investigated. To achieve this goal, three structural models including 5, 10, and 15 storey buildings are simulated in conjunction with a clayey soil representing soil class Eeaccording to the classification of AS1170.4–2007 (Earthquake actions in Australia) and then varying the Plasticity Index. Structural sections of the selected frames were designed according to AS3600–2009 (Australian Standard for Concrete Structures) after undertaking dynamic analysis under the influence of four different earthquake ground motions. The frame sections are modelled and analysed, employing finite difference method adopting FLAC 2D software under two different boundary conditions: (i) fixed base (no Soil-Structure Interaction), and (ii) flexible base considering soil-structure interaction. Fully nonlinear dynamic analyses under the influence of different earthquake records are conducted and the results in terms of maximum lateral displacements and inter-storey drifts for the above mentioned boundary conditions are obtained, compared, and discussed. Base on the results of the numerical investigations, it becomes apparent that as the Plasticity Index of the subsoil increases, the base shears of mid-rise building frames resting on soft soil deposits increase, while the lateral deflections and corresponding inter-storey drifts decrease. It is concluded that reduction of the Plasticity Index could noticeably amplify the effects of soil-structure interaction on the seismic response of mid-rise building frames.
Fatahi, B & Tabatabaiefar, SHR 2014, 'Fully Nonlinear versus Equivalent Linear Computation Method for Seismic Analysis of Midrise Buildings on Soft Soils', International Journal of Geomechanics, vol. 14, no. 4, pp. 04014016-04014016.
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In this study, the accuracy of a fully nonlinear method against an equivalent linear method for dynamic analysis of soil-structure interaction is investigated comparing the predicted results of both numerical procedures. Three structural models, including 5-story, 10-story, and 15-story buildings, are simulated in conjunction with two soil types with shear-wave velocities less than 600?m/s. The aforementioned frames were analyzed under three different conditions: (1) fixed-base model performing conventional time history dynamic analysis under the influence of earthquake records, (2) flexible-base model (considering full soil-structure interaction) conducting equivalent linear dynamic analysis of soil-structure interaction under seismic loads, and (3) flexible-base model performing fully nonlinear dynamic analysis of soil-structure interaction under the influence of earthquake records. The results of these three cases in terms of average lateral story deflections and interstory drifts are determined, compared, and discussed. It is concluded that the equivalent linear method of the dynamic analysis underestimates the inelastic seismic response of midrise moment resisting building frames resting on soft soils in comparison with the fully nonlinear dynamic analysis method. Therefore, a design procedure using the equivalent linear method cannot adequately guarantee the structural safety for midrise building frames resting on soft soils.
Fatahi, B, Basack, S, Ryan, P, Zhou, W-H & Khabbaz, H 2014, 'Performance of laterally loaded piles considering soil and interface parameters', GEOMECHANICS AND ENGINEERING, vol. 7, no. 5, pp. 495-524.
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© 2014 Techno-Press, Ltd. To investigate the soil-pile interactive performance under lateral loads, a set of laboratory model tests was conducted on remoulded test bed of soft clay and medium dense sand. Then, a simplified boundary element analysis had been carried out assuming floating pile. In case of soft clay, it has been observed that lateral loads on piles can initiate the formation of a gap, soil heave and the tension crack in the vicinity of the soil surface and the interface, whereas in medium dense sand, a semi-elliptical depression zone can develop. Comparison of test and boundary element results indicates the accuracy of the solution developed. However, in the boundary element analysis, the possible shear stresses likely to be developed at the interface are ignored in order to simplify the existing complex equations. Moreover, it is unable to capture the influence of base restraint in case of a socketed pile. To bridge up this gap and to study the influence of the initial stress state and interface parameters, a field based case-study of laterally-loaded pile in layered soil with socketed tip is explored and modelled using the finite element method. The results of the model have been verified against known field measurements from a case-study. Parametric studies have been conducted to investigate the influence of the coefficient of lateral earth pressure and the interface strength reduction factor on the results of the model.
Fatahi, B, Khabbaz, H & Indraratna, B 2014, 'Modelling of unsaturated ground behaviour influenced by vegetation transpiration', Geomechanics and Geoengineering, vol. 9, no. 3, pp. 187-207.
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Vegetation contributes to weak soil stabilisation through reinforcement of the soil, dissipation of excess pore pressure and increasing the shear strength by induced matric suction. This paper describes the way vegetation influences soil matric suction, shrinkage and ground settlement in the vadose zone through transpiration. A mathematical model for the rate of root water uptake, including the root growth rate considering ground conditions, type of vegetation and climatic parameters, has been developed. A finite element approach is employed to solve the transient coupled flow-deformation equations. The finite element mesh is built using partially saturated soil elements capable of representing the salient aspects of unsaturated permeability and the soil water characteristic curve. The model formulation is based on the effective stress theory of unsaturated soils. Based on this proposed model, the distribution of the ground matric suction profile adjacent to the tree is numerically analysed. Current field measurements of soil matric suction and moisture content collected from Miram site located in Victoria State, Australia by the authors are compared with the numerical predictions. The results indicate that the proposed root water uptake model incorporated in the numerical analysis can be used for prediction of ground properties influenced by tree roots. © 2014 Taylor & Francis.
Fatahi, B, Tabatabaiefar, SHR & Samali, B 2014, 'Soil-structure interaction vs Site effect for seismic design of tall buildings on soft soil', GEOMECHANICS AND ENGINEERING, vol. 6, no. 3, pp. 293-320.
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In this study, in order to evaluate adequacy of considering local site effect, excluding soil-structure interaction (SSI) effects in inelastic dynamic analysis and design of mid-rise moment resisting building frames, three structural models including 5, 10, and 15 storey buildings are simulated in conjunction with two soil types with the shear wave velocities less than 600 m/s, representing soil classes De and Ee according to the classification of AS1170.4-2007 (Earthquake actions in Australia) having 30 m bedrock depth. Structural sections of the selected frames were designed according to AS3600:2009 (Australian Standard for Concrete Structures) after undertaking inelastic dynamic analysis under the influence of four different earthquake ground motions. Then the above mentioned frames were analysed under three different boundary conditions: (i) fixed base under direct influence of earthquake records; (ii) fixed base considering local site effect modifying the earthquake record only; and (iii) flexible-base (considering full soil-structure interaction). The results of the analyses in terms of base shears and structural drifts for the above mentioned boundary conditions are compared and discussed. It is concluded that the conventional inelastic design procedure by only including the local site effect excluding SSI cannot adequately guarantee the structural safety for mid-rise moment resisting buildings higher than 5 storeys resting on soft soil deposits.
Ghanbarzadeh, R, Ghapanchi, AH & Blumenstein, M 2014, 'Application areas of multi-user virtual environments in the healthcare context.', Stud Health Technol Inform, vol. 204, pp. 38-46.
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This study conducts a systematic literature review on the application of the three-dimensional virtual worlds (3DVW) in healthcare context. During the past decade, 3DVWs have emerged as a cutting edge technology that has much to offer to the healthcare sector. Our systematic review began with an initial set of 1088 studies published from 1990 to 2013 which have used 3DVWs for the healthcare specific purposes. We found a variety of areas of application for the 3DVWs in healthcare, and categorised them into the following categories: education, treatment, evaluation, lifestyle and simulation. The presented big picture of application areas of 3DVWs in this study can be very valuable and insightful for the researchers and healthcare community.
Ghanbarzadeh, R, Ghapanchi, AH, Blumenstein, M & Talaei-Khoei, A 2014, 'A Decade of Research on the Use of Three-Dimensional Virtual Worlds in Health Care: A Systematic Literature Review', JOURNAL OF MEDICAL INTERNET RESEARCH, vol. 16, no. 2.
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Background: A three-dimensional virtual world (3DVW) is a computer-simulated electronic 3D virtual environment that users can explore, inhabit, communicate, and interact with via avatars, which are graphical representations of the users. Since the early 2000s, 3DVWs have emerged as a technology that has much to offer the health care sector. Objective: The purpose of this study was to characterize different application areas of various 3DVWs in health and medical context and categorize them into meaningful categories. Methods: This study employs a systematic literature review on the application areas of 3DVWs in health care. Our search resulted in 62 papers from five top-ranking scientific databases published from 1990 to 2013 that describe the use of 3DVWs for health care specific purposes. We noted a growth in the number of academic studies on the topic since 2006. Results: We found a wide range of application areas for 3DVWs in health care and classified them into the following six categories: academic education, professional education, treatment, evaluation, lifestyle, and modeling. The education category, including professional and academic education, contains the largest number of papers (n=34), of which 23 are related to the academic education category and 11 to the professional education category. Nine papers are allocated to treatment category, and 8 papers have contents related to evaluation. In 4 of the papers, the authors used 3DVWs for modeling, and 3 papers targeted lifestyle purposes. The results indicate that most of the research to date has focused on education in health care. We also found that most studies were undertaken in just two countries, the United States and the United Kingdom. Conclusions: 3D virtual worlds present several innovative ways to carry out a wide variety of health-related activities. The big picture of application areas of 3DVWs presented in this review could be of value and offer insights to both the health care communi...
Halkon, BJ & Rothberg, SJ 2014, 'Angular (pitch and yaw) vibration measurements directly from rotors using laser vibrometry', Mechanical Systems and Signal Processing, vol. 46, no. 2, pp. 344-360.
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Parallel beam laser vibrometers offer direct measurement of pitch and yaw vibration directly from rotors. This paper, intended as an essential guide for the practical parallel beam laser vibrometer practioner, presents exact mathematical expressions for measured angular velocity in the presence of inevitable misalignments and estimates the likely measurement error levels due to such misalignments as well as to other sources of uncertainty through numerical simulation. Cross-sensitivity to the orthogonal vibration component, i.e. cross-sensitivity in a pitch measurement to yaw motion and vice-versa, is confirmed for rough rotors whereas it is shown not to be present when rotors are polished-circular. A complementary experimental investigation of the relationship between surface roughness and cross-sensitivity confirms the identification of two preferred measurement configurations: from the side of a polished-circular rotor and from the end face of a (rough) rotor coated in retro-reflective tape. Rotors with surface roughness up to 50 nm satisfy the former case provided the vibration displacement at the rotor surface does not exceed 20% beam diameter. For surfaces with roughness of 10 nm this can be extended to 50%. For rough rotor end face measurements, post-processing is required to resolve the inherent cross-sensitivity; the need for post-processing is justified quantitatively through numerical simulation. Further simulations incorporating typical levels of instrument misalignment and measurement noise are used to enable quantification of the likely errors in such angular vibration measurements. For measurements from the side of a polished-circular rotor, errors are around 1% for amplitude and 10 mrad at integer orders affected by pseudo-vibration and around one-third of these levels elsewhere. For measurements from a rough rotor end face, errors will be similar at integer orders (from 2). Errors in the rotational speed measurement, required for post-p...
Hassaballa, AA, Althuwaynee, OF & Pradhan, B 2014, 'Extraction of soil moisture from RADARSAT-1 and its role in the formation of the 6 December 2008 landslide at Bukit Antarabangsa, Kuala Lumpur', Arabian Journal of Geosciences, vol. 7, no. 7, pp. 2831-2840.
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Heitor, A, Indraratna, B & Rujikiatkamjorn, C 2014, 'Assessment of the post-compaction characteristics of a siltysand', Australian Geomechanics Journal, vol. 49, no. 4, pp. 125-131.
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Conventional field compaction control methods are effective at the time of placement. However, the discrete nature of these measurements and a limited depth of investigation can render them unsuitable for post-construction compaction quality assessments of deeper fills or larger surface areas. In this situation, classical destructive geotechnical surveys (i.e. boreholes, cone penetration tests) are sought to evaluate the current fill conditions. Nevertheless, these methods often do not provide the required level of information because only certain locations are tested and they have tremendous implications in terms of cost. The use of available non-destructive methodologies, such as shear wave velocity surveys (i.e. SASW, spectral analysis of surface waves or HVSR, horizontal-to-vertical spectral ratio) together with electrical resistivity tomography surveys (e.g. evaluation of water content), offers a valuable alternative to efficiently control compaction over large areas during post-construction stages and locate areas within the existing formations where the soil was not sufficiently compacted. This study explores the performance of a cost effective method for evaluating the characteristics of compacted fills by measuring the shear wave velocity and matric suction to evaluate the void ratio or dry density of compacted soil. Laboratory studies of compacted specimens were used to evaluate this method and their performance under different isotropic confining pressures. The results showed that the shear wave velocity and matric suction can effectively predict how the soil is compacted, but its success requires field measurements of both shear wave velocity and matric suction. The application of this relationship would enable practitioners to efficiently control compaction over large areas during post-construction stages, and locate areas within the existing formations where the soil was not sufficiently compacted.
Ho, L, Fatahi, B & Khabbaz, H 2014, 'Analytical solution for one-dimensional consolidation of unsaturated soils using eigenfunction expansion method', INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, vol. 38, no. 10, pp. 1058-1077.
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This paper introduces an exact analytical solution for governing flow equations for one-dimensional consolidation in unsaturated soil stratum using the techniques of eigenfunction expansion and Laplace transformation. The homogeneous boundary conditions adopted in this study are as follows: (i) a one-way drainage system of homogenous soils, in which the top surface is considered as permeable to air and water, whereas the base is an impervious bedrock; and (ii) a two-way drainage system where both soil ends allow free dissipation of pore-air and pore-water pressures. In addition, the analytical development adopts initial conditions capturing both uniform and linear distributions of the initial excess pore pressures within the soil stratum. Eigenfunctions and eigenvalues are parts of the general solution and can be obtained based on the proposed boundary conditions. Besides, the Laplace transform method is adopted to solve the first-order differential equations. Once equations with transformed domain are all obtained, the final solutions, which are proposed to be functions of time and depth, can be achieved by taking an inverse Laplace transform. To verify the proposed solution, two worked examples are provided to present the consolidation characteristics of unsaturated soils based on the proposed method. The validation of the recent results against other existing analytical solutions is graphically demonstrated. © 2013 John Wiley & Sons, Ltd.
Hokmabadi, AS, Fatahi, B & Samali, B 2014, 'Assessment of soil-pile-structure interaction influencing seismic response of mid-rise buildings sitting on floating pile foundations', COMPUTERS AND GEOTECHNICS, vol. 55, no. 1, pp. 172-186.
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The role of the seismic soil-pile-structure interaction (SSPSI) is usually considered beneficial to the structural system under seismic loading since it lengthens the lateral fundamental period and leads to higher damping of the system in comparison with the fixed-base assumption. Lessons learned from recent earthquakes show that fixed-base assumption could be misleading, and neglecting the influence of SSPSI could lead to unsafe design particularly for structures founded on soft soils. In this study, in order to better understand the SSPSI phenomena, a series of shaking table tests have been conducted for three different cases, namely: (i) fixed-base structure representing the situation excluding the soil-structure interaction; (ii) structure supported by shallow foundation on soft soil; and (iii) structure supported by floating (frictional) pile foundation in soft soil. A laminar soil container has been designed and constructed to simulate the free field soil response by minimising boundary effects during shaking table tests. In addition, a fully nonlinear three dimensional numerical model employing FLAC3D has been adopted to perform time-history analysis on the mentioned three cases. The numerical model adopts hysteretic damping algorithm representing the variation of the shear modulus and damping ratio of the soil with the cyclic shear strain capturing the energy absorbing characteristics of the soil. Results are presented in terms of the structural response parameters most significant for the damage such as foundation rocking, base shear, floor deformation, and inter-storey drifts. Comparison of the numerical predictions and the experimental data shows a good agreement confirming the reliability of the numerical model. Both experimental and numerical results indicate that soil-structure interaction amplifies the lateral deflections and inter-storey drifts of the structures supported by floating pile foundations in comparison to the fixed base struc...
Huang, W, Sloan, SW & Sheng, D 2014, 'Analysis of plane Couette shear test of granular media in a Cosserat continuum approach', Mechanics of Materials, vol. 69, no. 1, pp. 106-115.
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Indraratna, B & Rujikiatkamjorn, C 2014, 'Geotechnical Engineering Journal of the Southeast Asian Geotechnical Society & Association of Geotechnical Societies in Southeast Asia PREFACE', GEOTECHNICAL ENGINEERING, vol. 45, no. 1.
Indraratna, B & Rujikiatkamjorn, C 2014, 'Preface', Geotechnical Engineering, vol. 45, no. 1.
Indraratna, B & Vinod, JS 2014, 'Editorial', Proceedings of the Institution of Civil Engineers - Ground Improvement, vol. 167, no. 1, pp. 1-1.
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Indraratna, B, Kianfar, K, Rujikiatkamjorn, C & Perera, D 2014, 'Soft clay properties for non-Darcian radial drainage with vacuum preloading, based on Rowe cell testing', Australian Geomechanics Journal, vol. 49, no. 4, pp. 183-190.
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Application of vacuum pressure with prefabricated vertical drains in soft clays is a popular and effective ground improvement method. Application of vacuum pressure via vertical drains generates a negative excess pore water pressure (PWP) resulting in an immediate increase in effective stress. This paper summarises the recent advancements in vacuum preloading based on laboratory studies, using the conventional and modified Rowe cells. Location and the magnitude of the average PWP and degree of consolidation during vacuum preloading are investigated. Based on the laboratory experiments a new radial consolidation model is proposed for vacuum preloading incorporating non-Darcian flow.
Indraratna, B, Navaratnarajah, SK, Nimbalkar, S & Rujikiatkamjorn, C 2014, 'Use of shock mats for enhanced stability of railroad track foundation', Australian Geomechanics Journal, vol. 49, no. 4, pp. 101-111.
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Increasing demand for High Speed Rail (HSR) and fast heavy haul poses a serious challenge for stability of tracks on problematic ground. Ballast is a key track foundation material placed underneath the sleepers which provides structural support against high cyclic and impact stresses caused by moving trains. Degradation of ballast contributes to a large percentage of track maintenance costs apart from affecting longevity and stability. In recent years, use of elastometric soft pads underneath sleepers has become increasingly popular as means of reducing track damage. The 'shock mat' placed under the sleeper is traditionally called Under Sleeper Pad (USP), and when it is placed under ballast, the term Under Ballast Mat (UBM) is often used. Currently there is lack of comprehensive assessment on the geotechnical behaviour of ballast using these artificial inclusions under impact and cyclic loading. In this study, a series of largescale laboratory tests were conducted to understand the performance of these energy absorbing 'shock mats' in the attenuation of impact and cyclic stresses and subsequent mitigation of ballast degradation. Impact loads were simulated using a high-capacity drop-weight impact testing equipment, while the cyclic loads were simulated using a large-scale prismoidal process simulation test apparatus. This paper presents a state-of-the-art review of laboratory studies and field trials demonstrating the benefits of USPs and UBMs in rail industry.
Indraratna, B, Ngo, NT & Rujikiatkamjorn, C 2014, 'Closure to “Deformation of Coal Fouled Ballast Stabilized with Geogrid under Cyclic Load” by Buddhima Indraratna, Ngoc Trung Ngo, and Cholachat Rujikiatkamjorn', Journal of Geotechnical and Geoenvironmental Engineering, vol. 140, no. 6, pp. 07014011-07014011.
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Indraratna, B, Ngo, NT, Rujikiatkamjorn, C & Vinod, JS 2014, 'Behavior of Fresh and Fouled Railway Ballast Subjected to Direct Shear Testing: Discrete Element Simulation', International Journal of Geomechanics, vol. 14, no. 1, pp. 34-44.
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This paper presents the three-dimensional discrete element method (DEM) that was used to study the shear behavior of fresh and coal fouled ballast in direct shear testing. The volumetric changes and stress-strain behavior of fresh and fouled ballast were simulated and compared with the experimental results. Clump logic in particle flow code in three dimensions (PFC3D) incorporated in a subroutine was used to simulate irregular-shaped particles in which groups of 10-20 spherical balls were clumped together in appropriate sizes to simulate ballast particles. Fouled ballast with a various void contaminant index (VCI) ranging from 20 to 70% VCI was modeled by injecting a specified number of miniature spherical particles into the voids of fresh ballast. The DEM simulation captures the behavior of fresh and fouled ballast as observed in the laboratory, showing that the peak shear stress of the ballast assembly decreases and the dilation of fouled ballast increases with an increasing VCI. Furthermore, the DEM also provides insight to the distribution of contact force chains and particle displacement vectors, which cannot be determined experimentally. These micromechanical observations clearly justify the formation of a shear band and the evolution of volumetric changes during shearing. The reduced maximum contact force associated with increased particle contact area due to fouling explains the decreased breakage of fouled ballast. An acceptable agreement was found between the DEM model predictions and laboratory data. © 2014 American Society of Civil Engineers.
Indraratna, B, Nimbalkar, S & Rujikiatkamjorn, C 2014, 'From theory to practice in track geomechanics – Australian perspective for synthetic inclusions', Transportation Geotechnics, vol. 1, no. 4, pp. 171-187.
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© 2014 Elsevier Ltd. The adoption of heavier axle loads and high speed rails have posed serious geotechnical issues with ballasted railway tracks. These issues include poor drainage of soft coastal soils, ballast degradation under cyclic and impact loads, differential settlement of track and misalignment due to lateral movements, and inadequate bearing capacity of some compacted ballast. The mechanisms of ballast degradation and deformation, the need for effective track confinement, understanding of interface behaviour, determining dynamic bearing capacity and use of energy absorbing shock mats and synthetic grids require further insight to improve the existing design guidelines for future high speed commuter and heavier freight trains. In this paper, the current state-of-the-art knowledge of rail track geomechanics is discussed, with particular emphasis on the effects of geosynthetic applications on ballast degradation, and track performance. The stress-strain response and volumetric changes of ballast stabilised with geosynthetics observed in the laboratory experiments were captured through discrete element and finite element models. Installing shock mats and geosynthetics in the track substructure led to the attenuation of high cyclic and impact forces, thereby mitigating ballast degradation. Comprehensive field studies on instrumented tracks at Bulli (near Wollongong) and Singleton (near Newcastle) supported by Sydney Trains and ARTC, were carried out to measure the in situ stresses and deformation of ballast embankments. The paper focuses primarily on research conducted at University of Wollongong for enhanced track performance, highlighting some examples of innovation from theory to practice.
Indraratna, B, Nimbalkar, S & Rujikiatkamjorn, C 2014, 'Preface', Transportation Geotechnics, vol. 1, no. 4, pp. 145-146.
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Indraratna, B, Nimbalkar, S, Coop, M & Sloan, SW 2014, 'A constitutive model for coal-fouled ballast capturing the effects of particle degradation', Computers and Geotechnics, vol. 61, pp. 96-107.
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Rail tracks undergo degradation owing to particle breakage and fouling of ballast by various fines including coal and subgrade soil. As the ballast becomes fouled, its strength and drainage capacity are compromised, sometimes resulting in differential settlement and reduced track stability. This paper demonstrates a continuum mechanics based framework to evaluate the detrimental effect of fines on the strength, deformation and degradation of coal-fouled ballast under monotonic loading. An elastoplastic constitutive model that considers the effect of fines content and energy consumption associated with particle breakage during shearing is presented. This multiphase constitutive model is developed within a critical state framework based on a kinematic-type yield locus and a modified stress-dilatancy approach. A general formulation for the rate of ballast breakage and coal particle breakage during triaxial shearing is presented and incorporated into the plastic flow rule to accurately predict the stress-strain response of coal-fouled ballast at various confining pressures. The behaviour of ballast at various levels of fouling is analysed and validated by experimental data. © 2014 Elsevier Ltd.
Indraratna, B, Pathirage, PU, Rowe, RK & Banasiak, L 2014, 'Coupled hydro-geochemical modelling of a permeable reactive barrier for treating acidic groundwater', Computers and Geotechnics, vol. 55, pp. 429-439.
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Indraratna, B, Premadasa, W, Brown, ET, Gens, A & Heitor, A 2014, 'Shear strength of rock joints influenced by compacted infill', International Journal of Rock Mechanics and Mining Sciences, vol. 70, pp. 296-307.
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Indraratna, B, Thirukumaran, S, Brown, ET, Premadasa, W & Gale, W 2014, 'A technique for three-dimensional characterisation of asperity deformation on the surface of sheared rock joints', International Journal of Rock Mechanics and Mining Sciences, vol. 70, pp. 483-495.
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Indraratna, PB & Vinod, DJS 2014, 'Editorial', Proceedings of the Institution of Civil Engineers - Ground Improvement, vol. 167, no. 3, pp. 147-148.
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Jebur, MN, Mohd Shafri, HZ, Pradhan, B & Tehrany, MS 2014, 'Per-pixel and object-oriented classification methods for mapping urban land cover extraction using SPOT 5 imagery', Geocarto International, vol. 29, no. 7, pp. 792-806.
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Jebur, MN, Pradhan, B & Tehrany, MS 2014, 'Detection of vertical slope movement in highly vegetated tropical area of Gunung pass landslide, Malaysia, using L-band InSAR technique', Geosciences Journal, vol. 18, no. 1, pp. 61-68.
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Jebur, MN, Pradhan, B & Tehrany, MS 2014, 'Optimization of landslide conditioning factors using very high-resolution airborne laser scanning (LiDAR) data at catchment scale', Remote Sensing of Environment, vol. 152, pp. 150-165.
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Jebur, MN, Pradhan, B, Shafri, HZM, Yusof, Z & Tehrany, MS 2014, 'An integrated user-friendly ArcMAP tool for bivariate statistical modeling in geoscience applications', Geoscientific Model Development Discussions, vol. 7, pp. 7239-7265.
Jebur, MN, Pradhan, B, Shafri, HZM, Yusof, Z & Tehrany, MS 2014, 'An integrated user-friendly ArcMAP tool for bivariate statistical modeling in geoscience applications', Geoscientific Model Development Discussions, vol. 7, pp. 7239-7265.
Jebur, MN, Pradhan, B, Shafri, HZM, Yusof, Z & Tehrany, MS 2014, 'An integrated user-friendly ArcMAP tool for bivariate statistical modeling in geoscience applications', Geoscientific Model Development Discussions, vol. 7, pp. 7239-7265.
Ji, JC 2014, 'Design of a nonlinear vibration absorber using three-to-one internal resonances', MECHANICAL SYSTEMS AND SIGNAL PROCESSING, vol. 42, no. 1-2, pp. 236-246.
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A weakly nonlinear vibration absorber is designed to attenuate the primary resonance vibrations of a single-degree-of-freedom weakly nonlinear oscillator having cubic nonlinearity. The linearised natural frequency of the nonlinear absorber is tuned to be approximately one-third the linearised natural frequency of the primary nonlinear oscillator. The low frequency mode for the absorber is favourably considered based on the fact that the nonlinear absorber can be easily realised in practice by using a light-weight mass attachment with small values of linear and nonlinear stiffness of coupling. For a given primary nonlinear oscillator and absorber mass, implementation of three-to-one internal resonances requires the smallest value of the absorber linear stiffness among three options for utilising internal resonances to design nonlinear absorber. The method of multiple scales is used to obtain the averaged equations that determine the amplitudes and phases of the first-order approximate solutions to the vibrations of the primary nonlinear oscillator and nonlinear absorber. It is found that the absorber response may admit either forced vibration having the forcing frequency or a combination of forced vibration and free-oscillation term having one third the forcing frequency. The nonlinear absorber can effectively suppress the amplitude of primary resonance response and eliminate saddle-node bifurcations occurring in the frequency-response curves of the primary nonlinear oscillator. Numerical results are given to show the effectiveness of the nonlinear absorber for suppressing nonlinear vibrations of the primary nonlinear oscillator under primary resonance conditions. © 2013 Elsevier Ltd. All rights reserved.
Ji, JC 2014, 'Secondary resonances of a quadratic nonlinear oscillator following two-to-one resonant Hopf bifurcations', NONLINEAR DYNAMICS, vol. 78, no. 3, pp. 2161-2184.
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© 2014, Springer Science+Business Media Dordrecht. Stable bifurcating solutions may appear in an autonomous time-delayed nonlinear oscillator having quadratic nonlinearity after the trivial equilibrium loses its stability via two-to-one resonant Hopf bifurcations. For the corresponding non-autonomous time-delayed nonlinear oscillator, the dynamic interactions between the periodic excitation and the stable bifurcating solutions can induce resonant behaviour in the forced response when the forcing frequency and the frequencies of Hopf bifurcations satisfy certain relationships. Under hard excitations, the forced response of the time-delayed nonlinear oscillator can exhibit three types of secondary resonances, which are super-harmonic resonance at half the lower Hopf bifurcation frequency, sub-harmonic resonance at two times the higher Hopf bifurcation frequency and additive resonance at the sum of two Hopf bifurcation frequencies. With the help of centre manifold theorem and the method of multiple scales, the secondary resonance response of the time-delayed nonlinear oscillator following two-to-one resonant Hopf bifurcations is studied based on a set of four averaged equations for the amplitudes and phases of the free-oscillation terms, which are obtained from the reduced four-dimensional ordinary differential equations for the flow on the centre manifold. The first-order approximate solutions and the nonlinear algebraic equations for the amplitudes and phases of the free-oscillation terms in the steady state solutions are derived for three secondary resonances. Frequency-response curves, time trajectories, phase portraits and Poincare sections are numerically obtained to show the secondary resonance response. Analytical results are found to be in good agreement with those of direct numerical integrations.
Jiang, X, Wang, J, Li, Y & Li, J 2014, 'Design and modelling of a novel linear electromagnetic vibration energy harvester', INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS, vol. 46, no. 1, pp. 165-183.
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This paper presents the design and evaluation of a novel permanent magnet (PM) energy harvesting system for scavenging electrical energy from ambient vibrations. A two-phase tubular linear PM vibration energy harvester consisting of a mover attached with permanent magnets and a slotted stator with built-in two-phase electromagnetic coils is proposed to convert vibrational kinetic energy into electrical energy. Aiming at maximizing the efficiency of vibration-to-electrical energy conversion under designated vibration and limited space requirement, a systematic research, including innovative device design, theoretical modelling and analysis, and finite element evaluation on the PM vibration energy harvester will be presented in this paper. In addition, the methodology of winding the two-phase coils in slotted stator is explicated in order to fully utilize the harvested electrical energy. A two-phase rectifier circuit is developed to convert the alternative voltage generated by the PM harvester into DC voltage that can be used directly by the external resistive load. Simulation results indicate that the proposed linear PM vibration energy harvesting system is able to generate about 100 watt DC electrical power under the vibration with the velocity of 0.4 m/s and the output electrical power is proportional to the levels of vibration excitations.
Jiang, XZ, Li, YC, Wang, J & Li, JC 2014, 'Electromechanical modeling and experimental analysis of a compression-based piezoelectric vibration energy harvester', International Journal of Smart and Nano Materials, vol. 5, no. 3, pp. 152-168.
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Over the past few decades, wireless sensor networks have been widely used in the field of structure health monitoring of civil, mechanical, and aerospace systems. Currently, most wireless sensor networks are battery-powered and it is costly and unsustainable for maintenance because of the requirement for frequent battery replacements. As an attempt to address such issue, this article theoretically and experimentally studies a compression-based piezoelectric energy harvester using a multilayer stack configuration, which is suitable for civil infrastructure system applications where large compressive loads occur, such as heavily vehicular loading acting on pavements. In this article, we firstly present analytical and numerical modeling of the piezoelectric multilayer stack under axial compressive loading, which is based on the linear theory of piezoelectricity. A two-degree-of-freedom electromechanical model, considering both the mechanical and electrical aspects of the proposed harvester, was developed to characterize the harvested electrical power under the external electrical load. Exact closed-form expressions of the electromechanical models have been derived to analyze the mechanical and electrical properties of the proposed harvester. The theoretical analyses are validated through several experiments for a test prototype under harmonic excitations. The test results exhibit very good agreement with the analytical analyses and numerical simulations for a range of resistive loads and input excitation levels. © 2014 The Author(s).
Khabbaz, H & Fatahi, B 2014, 'How to overcome geotechnical challenges in implementing high speed rail systems in Australia', Geotechnical Engineering, vol. 45, no. 1, pp. 39-47.
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Although there are a few medium speed rail systems in Australia, there is not a passenger rail transport with the high transit speed, seen in other countries. This paper firstly summarises lessons learnt from other countries, experienced high speed rail (HRS) for many years. Then, the challenges associated with implementing HSR systems in Australia are explained. The main challenges include selection and design of proper tracks, geographical issues, environmental concerns, economics and project costs and construction procedures. The second part of the paper presents the effective solutions to the geotechnical challenges associated with HSR systems. Various approaches are presented to improve the ballast layer properties and enhance the track formation bearing strength, stiffness, resiliency and dynamic properties. Employing concrete slab (ballast-less) tracks is also taken into consideration for HSR systems, and their performance is compared to ballasted tracks. Copyright © 2014 Southeast Asian Geotechnical Society (SEAGS). All Rights Reserved.
Khosrokhani, M & Pradhan, B 2014, 'Spatio-temporal assessment of soil erosion at Kuala Lumpur metropolitan city using remote sensing data and GIS', Geomatics, Natural Hazards and Risk, vol. 5, no. 3, pp. 252-270.
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Kouretzis, GP, Krabbenhøft, K, Sheng, D & Sloan, SW 2014, 'Soil-buried pipeline interaction for vertical downwards relative offset', Canadian Geotechnical Journal, vol. 51, no. 10, pp. 1087-1094.
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A new perspective is presented on the interaction effects for the vertical downwards offset of a pipeline relative to its surrounding soil. Instead of estimating the interaction force via shallow footing bearing capacity theory, as per common pipeline design practice, we assume that the vertical movement of the pipeline in uniform soil is governed by mechanisms similar to the lateral loading of a circular pile up to its limit load. The validity of this assumption is investigated numerically with the finite element limit analysis method, and design expressions are derived for the maximum interaction force on pipelines embedded in cohesive and granular soils. For the common case of buried pipelines built in sand-backfilled trenches, the same numerical method is employed to determine the necessary trench dimensions so as to avoid interaction with the possibly much stiffer native soil that results in a significant increase in the force applied on the pipeline during ground movement. The described approach can be employed in project-specific analyses to optimize trench dimensions, and thus avoid unnecessary excavation costs or mitigation measures.
Kouretzis, GP, Sheng, D & Wang, D 2014, 'Numerical simulation of cone penetration testing using a new critical state constitutive model for sand', Computers and Geotechnics, vol. 56, pp. 50-60.
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Lee, J, Guan, H, Loo, Y-C & Blumenstein, M 2014, 'Development of a Long-Term Bridge Element Performance Model Using Elman Neural Networks', Journal of Infrastructure Systems, vol. 20, no. 3, pp. 04014013-04014013.
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© 2014 American Society of Civil Engineers. A reliable deterioration model is essential in bridge asset management. Most deterioration modeling requires a large amount of well-distributed condition rating data along with all bridge ages to calculate the probability of condition rating deterioration. This means that the model can only function properly when a full set of data is available. To overcome this shortcoming, an improved artificial intelligence (AI)-based model is presented in this study to effectively predict long-term deterioration of bridge elements. The model has four major components: (1) categorizing bridge element condition ratings; (2) using the neural network-based backward prediction model (BPM) to generate unavailable historical condition ratings for applicable bridge elements; (3) training by an Elman neural network (ENN) for identifying historical deterioration patterns; and (4) using the ENN to predict long-term performance. The model has been tested using bridge inspection records that demonstrate satisfactory results. This study primarily focuses on the establishment of a new methodology to address the research problems identified. A series of case studies, hence, need to follow to ensure the method is appropriately developed and validated.
Li, JC, Li, HB, Jiao, YY, Liu, YQ, Xia, X & Yu, C 2014, 'Analysis for oblique wave propagation across filled joints based on thin-layer interface model', Journal of Applied Geophysics, vol. 102, pp. 39-46.
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Li, Y, Li, J, Li, W & Du, H 2014, 'A state-of-the-art review on magnetorheological elastomer devices', SMART MATERIALS AND STRUCTURES, vol. 23, no. 12.
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© 2014 IOP Publishing Ltd. During the last few decades, magnetorheological (MR) elastomers have attracted a significant amount of attention for their enormous potential in engineering applications. Because they are a solid counterpart to MR fluids, MR elastomers exhibit a unique field-dependent material property when exposed to a magnetic field, and they overcome major issues faced in magnetorheological fluids, e.g. the deposition of iron particles, sealing problems and environmental contamination. Such advantages offer great potential for designing intelligent devices to be used in various engineering fields, especially in fields that involve vibration reduction and isolation. This paper presents a state of the art review on the recent progress of MR elastomer technology, with special emphasis on the research and development of MR elastomer devices and their applications. To keep the integrity of the knowledge, this review includes a brief introduction of MR elastomer materials and follows with a discussion of critical issues involved in designing magnetorheological elastomer devices, i.e. operation modes, coil placements and principle fundamentals. A comprehensive review has been presented on the research and development of MR elastomer devices, including vibration absorbers, vibration isolators, base isolators, sensing devices, and so on. A summary of the research on the modeling mechanical behavior for both the material and the devices is presented. Finally, the challenges and the potential facing magnetorheological elastomer technology are discussed, and suggestions have been made based on the authors' knowledge and experience.
Li, Y, Li, J, Tian, T & Li, W 2014, 'A highly adjustable magnetorheological elastomer base isolator for applications of real-time adaptive control (vol 22, 095020, 2013)', SMART MATERIALS AND STRUCTURES, vol. 23, no. 12.
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Li, Z, Zhang, B, Wang, Y, Chen, F, Taib, R, Whiffin, V & Wang, Y 2014, 'Water pipe condition assessment: a hierarchical beta process approach for sparse incident data', Machine Learning, vol. 95, no. 1, pp. 11-26.
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Liang, D-F & He, X-Z 2014, 'A comparison of conventional and shear-rate dependent Mohr-Coulomb models for simulating landslides', Journal of Mountain Science, vol. 11, no. 6, pp. 1478-1490.
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Liu, Y, Li, H, Xiao, K, Li, J, Xia, X & Liu, B 2014, 'Seismic stability analysis of a layered rock slope', Computers and Geotechnics, vol. 55, pp. 474-481.
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Lloret-Cabot, M, Wheeler, SJ, Pineda, JA, Sheng, D & Gens, A 2014, 'Relative performance of two unsaturated soil models using different constitutive variables', Canadian Geotechnical Journal, vol. 51, no. 12, pp. 1423-1437.
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Mechanical and water retention behaviour of unsaturated soils is investigated in the context of two well established coupled constitutive models, each of which is formulated in terms of a different set of stress state variables or constitutive variables. Incremental relationships describing the volume change and variation of the degree of saturation are derived for each model. These incremental relationships are used to simulate a set of experimental tests on compacted Speswhite kaolin previously reported in the literature. Six individual tests, involving isotropic compression and various forms of shearing, are analyzed in the context of the incremental forms developed, and the model predictions are then compared against experimental results. The results show that, although each constitutive model uses a different set of constitutive variables and a different scheme for coupling mechanical and water retention behaviour, the two sets of model predictions are similar and both sets provide a reasonable match to the experimental results, suggesting that both models are able to capture the relevant features of unsaturated soil behaviour, despite expressing the constitutive laws in different ways.
Manap, MA, Nampak, H, Pradhan, B, Lee, S, Sulaiman, WNA & Ramli, MF 2014, 'Application of probabilistic-based frequency ratio model in groundwater potential mapping using remote sensing data and GIS', Arabian Journal of Geosciences, vol. 7, no. 2, pp. 711-724.
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Mohammadi, I, Khabbaz, H & Vessalas, K 2014, 'In-depth assessment of Crumb Rubber Concrete (CRC) prepared by water-soaking treatment method for rigid pavements', CONSTRUCTION AND BUILDING MATERIALS, vol. 71, pp. 456-471.
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© 2014 Elsevier Ltd. All rights reserved. This paper investigates effects of applying an innovative method of rubber treatment, named water-soaking, on fresh and hardened properties of rubberised concrete. Unlike the current methods of introducing rubber into concrete mixtures, which are conducted in a dry process, this research trialled introducing of rubber particles into the mixture in a wet process. Conducting the required sets of fresh and hardened concrete tests, mixtures with a variety of rubber content and water-cement ratios were evaluated. In order to measure the effectiveness of the introduced method, properties of concrete prepared by water soaking-method were compared with concrete containing untreated rubber. It was observed that applying the proposed method resulted in improvement of fresh and hardened properties. It resulted in more uniform distribution of rubber particles in concrete matrix, less entrapped air in concrete mixture and 22% higher compressive strength for rubberised concrete.
Mohammed, OI, Saeidi, V, Pradhan, B & Yusuf, YA 2014, 'Advanced differential interferometry synthetic aperture radar techniques for deformation monitoring: a review on sensors and recent research development', Geocarto International, vol. 29, no. 5, pp. 536-553.
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Mohammed, OI, Saeidi, V, Pradhan, B & Yusuf, YA 2014, 'Advanced differential interferometry synthetic aperture radar techniques for deformation monitoring: a review on sensors and recent research development', Geocarto International, vol. 29, no. 5, pp. 536-553.
Movassaghi, S, Abolhasan, M, Lipman, J, Smith, D & Jamalipour, A 2014, 'Wireless Body Area Networks: A Survey', IEEE COMMUNICATIONS SURVEYS AND TUTORIALS, vol. 16, no. 3, pp. 1658-1686.
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Recent developments and technological advancements in wireless communication, MicroElectroMechanical Systems (MEMS) technology and integrated circuits has enabled low-power, intelligent, miniaturized, invasive/non-invasive micro and nano-technology sensor nodes strategically placed in or around the human body to be used in various applications, such as personal health monitoring. This exciting new area of research is called Wireless Body Area Networks (WBANs) and leverages the emerging IEEE 802.15.6 and IEEE 802.15.4j standards, specifically standardized for medical WBANs. The aim of WBANs is to simplify and improve speed, accuracy, and reliability of communication of sensors/actuators within, on, and in the immediate proximity of a human body. The vast scope of challenges associated with WBANs has led to numerous publications. In this paper, we survey the current state-of-art of WBANs based on the latest standards and publications. Open issues and challenges within each area are also explored as a source of inspiration towards future developments in WBANs. © 2014 IEEE.
Mustapha, S, Lu, Y, Li, J & Ye, L 2014, 'Damage detection in rebar-reinforced concrete beams based on time reversal of guided waves', Structural Health Monitoring, vol. 13, no. 4, pp. 347-358.
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The propagation properties of ultrasonic waves in rebar-reinforced concrete beams were investigated and their ability for damage identification was demonstrated. Rectangular piezoelectric ceramics were attached at the exposed ends of the rebar to monitor the wave transmission along the rebar with and without simulated corrosion, which was introduced in the form of partial removal of material from the rebar. Experimental testing demonstrated that the presence of concrete had a significant influence on the propagation characteristics of guided waves along the rebar. In consideration of the inevitable discrepancies in different concrete beams due to individual specimen preparation and sensor installation, the time-reversal process was applied to identify the damage. A damage index was defined based on the correlation coefficient between the actuated and the reconstructed wave signals. Wavelet transform was applied to overcome the wave conversion difficulty and to reduce the noise in the captured wave signals. Damage of different sizes was introduced and then was correlated with the damage index. Enlarging the damage size resulted in an increase in the level of distortion in the reconstructed wave signals, and consequently, a higher damage index was obtained. The results demonstrate the efficiency of the time-reversal process in identifying damage in rebar-reinforced concrete structures.
NAMPAK, H 2014, 'DEVELOPMENT OF OPTIMIZED MODEL BASED ON EVIDENTIAL BELIEF FUNCTION FOR GROUNDWATER MAPPING'.
Nampak, H, Pradhan, B & Manap, MA 2014, 'Application of GIS based data driven evidential belief function model to predict groundwater potential zonation', Journal of Hydrology, vol. 513, pp. 283-300.
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Neshat, A, Pradhan, B & Dadras, M 2014, 'Groundwater vulnerability assessment using an improved DRASTIC method in GIS', Resources, Conservation and Recycling, vol. 86, pp. 74-86.
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Neshat, A, Pradhan, B & Shafri, HZM 2014, 'An Integrated GIS Based Statistical Model to Compute Groundwater Vulnerability Index for Decision Maker in Agricultural Area', Journal of the Indian Society of Remote Sensing, vol. 42, no. 4, pp. 777-788.
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Neshat, A, Pradhan, B, Pirasteh, S & Shafri, HZM 2014, 'Estimating groundwater vulnerability to pollution using a modified DRASTIC model in the Kerman agricultural area, Iran', Environmental Earth Sciences, vol. 71, no. 7, pp. 3119-3131.
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Ngo, NT, Indraratna, B & Rujikiatkamjorn, C 2014, 'DEM simulation of the behaviour of geogrid stabilised ballast fouled with coal', Computers and Geotechnics, vol. 55, pp. 224-231.
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Geogrids are commonly used in railway construction for reinforcement and stabilisation. When railway ballast becomes fouled due to ballast breakage, infiltration of coal fines, dust and subgrade soil pumping, the reinforcement effect of geogrids decreases significantly. This paper presents results obtained from Discrete Element Method (DEM) to study the interface behaviour of coal-fouled ballast reinforced by geogrid subjected to direct shear testing. In this study, irregularly-shaped aggregates (ballast) were modelled by clumping together 10-20 spheres in appropriate sizes and positions. The geogrid was modelled by bonding a large number of small spheres together to form the desired grid geometry and apertures. Fouled ballast with 40% Void Contaminant Index (VCI) was modelled by injecting a predetermined number of miniature spheres into the voids of fresh ballast. A series of direct shear tests for fresh and fouled ballast reinforced by the geogrid subjected to normal shear stresses varying from 15. kPa to 75. kPa were then simulated in the DEM. The numerical results showed a good agreement the laboratory data, indicating that the DEM model is able to capture the behaviour of both fresh and coal-fouled ballast reinforced by the geogrid. The advantages of the proposed DEM model in terms of capturing the correct stress-displacement and volumetric behaviour of ballast, as well as the contact forces and strains developed in the geogrids are discussed. © 2013 Elsevier Ltd.
Nguyen, LD, Fatahi, B & Khabbaz, H 2014, 'A constitutive model for cemented clays capturing cementation degradation', INTERNATIONAL JOURNAL OF PLASTICITY, vol. 56, pp. 1-18.
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Laboratory experiments show that the effect of cementation on clays gradually diminishes as the confining pressure increases (particularly at high confining pressures) due to the degradation of cementation bonds. The main aim of this paper is to propose a constitutive model for cemented clays, referred to as the Cemented Cam Clay model (CCC), to simulate the cementation degradation during loading. The failure envelope of the proposed model is formulated to describe the behaviour of the cemented clay at a low pressure range similar to over-consolidated soils, while it merges with the Critical State Line of reconstituted sample gradually as the confining pressure continues to increase. In order to examine the stress-strain behaviour of cemented clays, an energy dissipation equation is developed inspired by the Modified Cam Clay model. The characteristics of the proposed model, including a non-associated plastic potential function and elasto-plastic stress-strain relationship, are presented in light of the Critical State concept. Validity of the proposed constitutive model derived from the modified energy equation is evaluated against triaxial test results for cemented clays available in literature. © 2014 Published by Elsevier Ltd. All rights reserved.
Ni, J, Indraratna, B, Geng, XY, Chen, YL & Zhu, Y 2014, 'Experimental study of the combined effect of cyclic stress level and loading frequency on the performance of soft clays', Gongcheng Lixue/Engineering Mechanics, vol. 31, no. 10, pp. 167-173.
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Undrained cyclic triaxial tests were conducted on soft clay to investigate the combined effect of cyclic stress level and loading frequency on the generation of excess pore water pressures and axial strains with the number of loading cycles or time. The results indicate that for a given cyclic stress level, the soil properties under various loading frequencies are slightly different if an identical number of loading cycles is considered, whereas they do not deviate from each other if an identical time is considered. In addition, failure occurs when the cyclic stress level exceeds a critical value irrespective of the loading frequency. The combined effect of a cyclic stress level and a loading frequency was studied by analyzing the strain rate in this stress-controlled cyclic loading test. It is shown that for a given cyclic stress level, the strain rate at various loading frequencies are almost same, implying that the influence of a cyclic stress level on the soft clay behavior is stronger compared to a loading frequency.
Nourani, V, Pradhan, B, Ghaffari, H & Sharifi, SS 2014, 'Landslide susceptibility mapping at Zonouz Plain, Iran using genetic programming and comparison with frequency ratio, logistic regression, and artificial neural network models', Natural Hazards, vol. 71, no. 1, pp. 523-547.
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Oberst, S, Baro, EN, Lai, JCS & Evans, TA 2014, 'Quantifying Ant Activity Using Vibration Measurements', PLoS ONE, vol. 9, no. 3, pp. e90902-e90902.
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Oberst, S, Evans, TA & Lai, JCS 2014, 'Novel Method for Pairing Wood Samples in Choice Tests', PLoS ONE, vol. 9, no. 2, pp. e88835-e88835.
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Oyekanmi, AA, Daud, N, Norsyahariati, N, Ahsan, A & Pradhan, B 2014, 'Water quality assessment of UPM lake and the impact of geographic information system', International Journal of Environmental Monitoring and Analysis, vol. 2, no. 3, pp. 158-162.
Pal, S, Pal, U & Blumenstein, M 2014, 'Signature-Based Biometric Authentication', Studies in Computational Intelligence, vol. 555, pp. 285-314.
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In a modern, civilized and advanced society, reliable authentication and authorization of individuals are becoming more essential tasks in several aspects of daily activities and as well as many different important applications such as in financial transactions, access control, travel and immigration, healthcare etc. In some situations, when individual equipment is required for confirmation of one's identity to other groups of people in order to make use of services or to achieve access to physical places, it is always necessary to declare self-identity and to prove the claim. Traditional authentication methods, which are based on knowledge (password-based authentication) or the utility of a token (photo ID cards, magnetic strip cards and key-based authentication), are less reliable because of loss, forgetfulness and theft. These issues direct substantial attention towards biometrics as an alternative method for person authentication and identification. The word 'biometric' has been derived from the Greek words "Bio-metriks", "Bio" which means life and "metriks" which means measures. Therefore a biometric is the measurement and statistical analysis of unchanging biological characteristics. Biometrics evaluate a person's unique physical or behavioural traits to authenticate their identity. As biometric identifiers are unique to persons, they are more reliable in verifying identity than token-based and knowledge-based methods. In the last few years, substantial efforts have been devoted to the development of biometric-based authentication systems. Biometrics provide an expected and successful solution to the authentication problem, as it offers the construction of systems that can identify individuals by the analysis of their physiological or behavioural characteristics [1]. In fact, the field of biometrics is the science of using digital technologies and the intention of biometric systems is to perform the recognition or authentication of people based on some biol...
Parsa-Pajouh, A, Fatahi, B, Vincent, P & Khabbaz, H 2014, 'Analyzing consolidation data to predict smear zone characteristics induced by vertical drain installation for soft soil improvement', GEOMECHANICS AND ENGINEERING, vol. 7, no. 1, pp. 105-131.
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In this paper, the effects of variability of smear zone characteristics induced by installation of prefabricated vertical drains on the preloading design are investigated employing analytical and numerical approaches. Conventional radial consolidation theory has been adopted to conduct analytical parametric studies considering variations of smear zone permeability and extent. FLAC 2D finite difference software has been employed to conduct the numerical simulations. The finite difference analyses have been verified using three case studies including two embankments and a large-scale laboratory consolidometer with a central geosynthetic vertical drain. A comprehensive numerical parametric study is conducted to investigate the influence of smear zone permeability and extent on the model predictions. Furthermore, the construction of the trial embankment is recommended as a reliable solution to estimate accurate smear zone properties and minimise the post construction settlement. A back-calculation procedure is employed to determine the minimum required waiting time after construction of the trial embankment to predict the smear zone characteristics precisely. Results of this study indicate that the accurate smear zone permeability and extent can be back-calculated when 30% degree of consolidation is obtained after construction of the trial embankment. © 2014 Techno-Press, Ltd.
Parsa-Pajouh, A, Fatahi, B, Vincent, P & Khabbaz, H 2014, 'Trial Embankment Analysis to Predict Smear Zone Characteristics Induced by Prefabricated Vertical Drain Installation', Geotechnical and Geological Engineering, vol. 32, no. 5, pp. 1187-1210.
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© 2014, Springer International Publishing Switzerland. In this study, FLAC finite difference software has been adopted to simulate the performance of the ground improved using prefabricated vertical drains assisted preloading, considering smear zone characteristics. The numerical code has been applied to predict smear zone properties employing a back calculation procedure using the results of several case studies. The construction of a trial embankment is proposed as a reliable method to predict the smear zone characteristics. The proposed back calculation method is applied to estimate the minimum required degree of consolidation and consequently the minimum required preloading time, resulting in a reliable estimation of the smear zone permeability and extent. Three preloading case studies considering both conventional preloading and vacuum assisted preloading have been simulated to verify the numerical code and to conduct the parametric study using the back calculation procedure. According to the results, the properties of the smear zone can be back-calculated reliably, when at least 33 % degree of consolidation due to trial embankment construction is achieved.
Perrin, R, Elford, DP, Chalmers, L, Swallowe, GM, Moore, TR, Hamdan, S & Halkon, BJ 2014, 'Normal modes of a small gamelan gong', The Journal of the Acoustical Society of America, vol. 136, no. 4, pp. 1942-1950.
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Studies have been made of the normal modes of a 20.7 cm diameter steel gamelan gong. A finite-element model has been constructed and its predictions for normal modes compared with experimental results obtained using electronic speckle pattern interferometry. Agreement was reasonable in view of the lack of precision in the manufacture of the instrument. The results agree with expectations for an axially symmetric system subject to small symmetry breaking. The extent to which the results obey Chladni's law is discussed. Comparison with vibrational and acoustical spectra enabled the identification of the small number of modes responsible for the sound output when played normally. Evidence of non-linear behavior was found, mainly in the form of subharmonics of true modes. Experiments using scanning laser Doppler vibrometry gave satisfactory agreement with the other methods.
PINEDA, JA, ROMERO, E, DE GRACIA, M & SHENG, D 2014, 'Shear strength degradation in claystones due to environmental effects', Géotechnique, vol. 64, no. 6, pp. 493-501.
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This note explores the influence of environmental effects, as those induced by cyclic changes in relative humidity, on the degradation of the shear strength parameters in Lilla claystone, a low-porosity clayey rock from northern Spain. The results of a comprehensive experimental programme, combining long-term relative humidity cycling tests with saturated direct shear tests, are described. A continuous monitoring of the evolution of volumetric strain during the previous relative humidity cycling is used to evaluate the swelling behaviour of the rock. Both undisturbed and degraded specimens are subjected to shearing at saturated conditions to determine the peak and post-rupture shear strength envelopes. The effects on rock brittleness and dilation angle are also analysed. Shear strength shows a strong dependence on the history of relative humidity cycling. In particular, the evolution of the peak shear strength parameters (c′ and φ′) seem to be related to the accumulated irreversible strains developed during each cycle. A damage law, recently proposed by the authors, is used to represent the progressive degradation of the shear strength parameters as a function of the accumulated irreversible strains.
Pourghasemi, HR, Moradi, HR, Fatemi Aghda, SM, Gokceoglu, C & Pradhan, B 2014, 'GIS-based landslide susceptibility mapping with probabilistic likelihood ratio and spatial multi-criteria evaluation models (North of Tehran, Iran)', Arabian Journal of Geosciences, vol. 7, no. 5, pp. 1857-1878.
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Pourghasemi, HR, Moradi, HR, Fatemi Aghda, SM, Sezer, EA, Goli Jirandeh, A & Pradhan, B 2014, 'Assessment of fractal dimension and geometrical characteristics of the landslides identified in North of Tehran, Iran', Environmental Earth Sciences, vol. 71, no. 8, pp. 3617-3626.
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Pradhan, B, Abokharima, MH, Jebur, MN & Tehrany, MS 2014, 'Land subsidence susceptibility mapping at Kinta Valley (Malaysia) using the evidential belief function model in GIS', Natural Hazards, vol. 73, no. 2, pp. 1019-1042.
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Pradhan, B, Hagemann, U, Shafapour Tehrany, M & Prechtel, N 2014, 'An easy to use ArcMap based texture analysis program for extraction of flooded areas from TerraSAR-X satellite image', Computers & Geosciences, vol. 63, pp. 34-43.
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Regmi, AD, Devkota, KC, Yoshida, K, Pradhan, B, Pourghasemi, HR, Kumamoto, T & Akgun, A 2014, 'Application of frequency ratio, statistical index, and weights-of-evidence models and their comparison in landslide susceptibility mapping in Central Nepal Himalaya', Arabian Journal of Geosciences, vol. 7, no. 2, pp. 725-742.
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Regmi, AD, Yoshida, K, Dhital, MR & Pradhan, B 2014, 'Weathering and mineralogical variation in gneissic rocks and their effect in Sangrumba Landslide, East Nepal', Environmental Earth Sciences, vol. 71, no. 6, pp. 2711-2727.
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Regmi, AD, Yoshida, K, Nagata, H & Pradhan, B 2014, 'Rock toppling assessment at Mugling–Narayanghat road section: ‘A case study from Mauri Khola landslide’, Nepal', CATENA, vol. 114, pp. 67-77.
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Regmi, AD, Yoshida, K, Pourghasemi, HR, DhitaL, MR & Pradhan, B 2014, 'Landslide susceptibility mapping along Bhalubang — Shiwapur area of mid-Western Nepal using frequency ratio and conditional probability models', Journal of Mountain Science, vol. 11, no. 5, pp. 1266-1285.
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Remennikov, AM, Mutton, V, Nimbalkar, S & Ren, T 2014, 'Experimental and numerical investigation of high-yield grout ore pass plugs to resist impact loads', INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES, vol. 70, pp. 1-15.
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In the last fifteen years, Tekseal high yield foaming grout ore pass plugs that could later be easily removed, have been poured above chute maintenance areas providing protection from high energy rock impact and isolating workers from the hazard. Construction and removal methods will be briefly explained. Since it is not economically feasible to investigate the problem of ore pass plug impact response using full-scale experimental studies, this paper presents a combined four-stage approach that includes (1) laboratory testing to investigate the mechanical behaviour of the high-yield foaming grout; (2) high-precision impact testing of reduced-scale models of ore pass plugs; (3) high-fidelity physics-based numerical model calibration using experimental data; and (4) full-scale modelling of mine ore pass plugs using calibrated material models. To calibrate numerical models, three one-metre diameter steel pipes filled with Tekseal high yield foaming grout were tested with falling steel projectiles of different shapes. Impact tests provided data on the depth of penetration and size of the craters formed by the projectiles. Numerical models were calibrated by optimising the material parameters and modelling techniques to provide the best match with the experimental results. Full-scale numerical models of ore pass plugs were developed for typical ore pass dimensions and subjected to impact events by falling rock projectiles. The proposed approach has allowed investigating energy absorbing characteristics of ore pass plugs to further predict and increase understanding of their capacity to withstand high-speed impacts by large falling projectiles. © 2014 Elsevier Ltd.
Sabbagh, AAL, Braun, R & Abolhasan, M 2014, 'Intelligent Hybrid Cheapest Cost and Mobility Optimization RAT Selection Approaches for Heterogeneous Wireless Networks', Journal of Networks, vol. 9, no. 2, pp. 297-305.
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The evolution of wireless networks has led to the deployment of different Radio Access Technologies (RATs) such as UMTS Terrestrial Radio Access Network (UTRAN), Long Term Evolution (LTE), Wireless Local Area Network (WLAN) and Mobile Worldwide Interoperability for Microwave Access (WiMAX) which are integrated through a common platform. Common Radio Resource Management (CRRM) was proposed to manage radio resource utilization in heterogeneous wireless networks and to provide the required Quality of Service (QoS) for allocated calls. RAT selection algorithms are an integral part of the CRRM algorithms. Their role is to decide, when a new or Vertical Handover (VHO) call is requested, which of the available RATs is most suitable to fit the need of the incoming call and when to admit them. This paper extends our earlier work on the proposed intelligent mobility optimization and proposes an intelligent hybrid cheapest cost RAT selection approach which aims to increase users' satisfaction by allocation users that are looking for cheapest cost connections to a RAT that offers the cheapest cost of service. A comparison for the performance of centralized load-balancing, proposed and distributed cheapest cost and mobility optimization algorithms is presented. Simulation results show that the proposed intelligent algorithms perform better than the centralized load-balancing and the distributed algorithms. © 2014 Academy Publisher.
Sabbagh, AAL, Braun, R & Abolhasan, M 2014, 'Performance Analysis of the Intelligent Mobility Optimization CRRM Approach Using a Markovian Chain Model', Journal of Networks, vol. 9, no. 3, pp. 635-644.
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Due to the increasing demand of wireless services, mobile technology has rapidly progressed towards the fourth generation (4G) networking paradigm. This generation will be heterogeneous in nature and it can be achieved through the integration of different Radio Access Technologies (RATs) over a common platform. Common Radio Resource Management (CRRM) was proposed to manage radio resource utilization in heterogeneous wireless networks and to provide required Quality of Service (QoS) for allocated calls. RAT selection algorithms are an integral part of the CRRM algorithms. Their role is to decide, when a new or Vertical Handover (VHO) call is requested, which of the available RATs is most suitable to fit the need of the incoming call and when to admit them. This paper extends our earlier work on the proposed intelligent hybrid mobility optimization RAT selection approach which allocates users in high mobility to the most suitable RAT and proposes an analytical presentation of the proposed approach in a multidimensional Markov chain model. A comparison for the performance of centralized load-balancing, distributed and the proposed intelligent mobility optimization algorithms is presented in terms of new calls blocking probability, VHO calls dropping probability, users' satisfactions probability, average networks load and average system throughput. Simulation and analytical results show that the proposed algorithm performs better than the centralized loadbalancing and distributed algorithms. © 2014 ACADEMY PUBLISHER.
Saeidi, V, Pradhan, B, Idrees, MO & Abd Latif, Z 2014, 'Fusion of Airborne LiDAR With Multispectral SPOT 5 Image for Enhancement of Feature Extraction Using Dempster–Shafer Theory', IEEE Transactions on Geoscience and Remote Sensing, vol. 52, no. 10, pp. 6017-6025.
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Saeidi, V, Pradhan, B, Idrees, MO & Latif, ZA 2014, 'Fusion of airborne lidar with multispectral spot 5 image for enhancement of feature extraction using dempster–shafer theory', IEEE Transactions on Geoscience and Remote Sensing, vol. 52, no. 10, pp. 6017-6025.
Salleh, SA, Latif, ZA, Pradhan, B, Wan Mohd, WMN & Chan, A 2014, 'Functional relation of land surface albedo with climatological variables: a review on remote sensing techniques and recent research developments', Geocarto International, vol. 29, no. 2, pp. 147-163.
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Sheng, D, Zhang, S & He, Z 2014, 'Assessing frost susceptibility of soils', Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering, vol. 33, no. 3, pp. 594-605.
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Frost heave is assumed to be caused by the formation of ice lenses in a freezing soil. The formation of ice lenses is governed by the Clapeyron equation of thermodynamics and relies on the existence of a frozen fringe between frozen and unfrozen zones. Both unfrozen water and ice co-exist in pores of the frozen fringe. The suction at water-ice interface is the driving force for water flow that feeds the growth of ice lens. The initiation of a new ice lens is governed by a simple effective stress concept. Then a simple frost heave model is presented. The frost heave model contains only a few soil parameters and can be used to compute frost heave and frost penetration in stratified soil profiles. The second part of the paper illustrates the application of the frost heave model in assessing the frost susceptibility of different soils. It is shown that the frost susceptibility of a soil must be assessed together with environmental conditions such as overburden pressure, temperature gradient, cooling rate and the depth of groundwater table. A soil that is only mildly susceptible to frost according to classification can still generate a significant amount of heave or heaving pressure under favourable environmental conditions.
SHENG, D, ZHANG, S, NIU, F & CHENG, G 2014, 'A potential new frost heave mechanism in high-speed railway embankments', Géotechnique, vol. 64, no. 2, pp. 144-154.
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Substantial frost heave has been observed in coarse fills in high-speed railway embankments. These coarse fills have very low water contents, and are located above the groundwater table. In an attempt to explain the unexpected frost heave, it is proposed that cyclic train loads cause the development of excess pore water pressure in the underlying subgrade soil, and hence ‘pump' up the water table to the frost front, which in turn feeds the formation of ice and results in continuous frost heave. A simple quantitative model is then developed to simulate the pumping-enhanced frost heave. The numerical results show that the proposed mechanism can indeed provide a rational explanation for the otherwise unexpected frost heave. The engineering implications of this new frost heave mechanism are also discussed, in the context of designing frost heave mitigation measures in seasonally frozen regions.
Shoa, TZ, Nateghi, S, Nohegar, A, Amiri, F & Pradhan, B 2014, 'Sediment yield assessment at basin scale using geospatial technique', Arabian Journal of Geosciences, vol. 7, no. 7, pp. 2841-2850.
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SUN, QD, INDRARATNA, B & NIMBALKAR, S 2014, 'Effect of cyclic loading frequency on the permanent deformation and degradation of railway ballast', Géotechnique, vol. 64, no. 9, pp. 746-751.
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A series of large-scale cyclic triaxial tests were conducted on latite basalt aggregates (ballast) to investigate how the frequency f affects the permanent deformation and degradation of railway ballast. During testing the frequency was varied from 5 Hz to 60 Hz to simulate a range of train speeds from about 40 km/h to 400 km/h. Three categories of permanent deformation mechanisms were observed in response to the applied cyclic loads, namely, the inception of plastic shakedown (f ≤ 20 Hz), then plastic shakedown and ratcheting (30 Hz ≤ f ≤ 50 Hz), followed by plastic collapse at higher frequencies (f ≥ 60 Hz). The permanent strain of ballast and particle breakage increased with the frequency and number of load cycles. A cyclic strain ratio was introduced to capture the effect of frequency on the permanent axial and volumetric strains, respectively. An empirical equation was formulated to represent this relationship for latite basalt, and a critical train speed was identified. A good correlation was obtained between particle breakage and volumetric strain under cyclic loading.
Sun, Y, Indraratna, B & Nimbalkar, S 2014, 'Three-dimensional characterisation of particle size and shape for ballast', Géotechnique Letters, vol. 4, no. 3, pp. 197-202.
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The size and shape of particles influence how effectively coarse angular aggregates of ballast interact. The aim of this study was to improve the characterisation of ballast particles using a three-dimensional (3D) imaging method. Various size and shape indices, such as elongation ratio, sphericity and roundness, were determined from the scanned 3D images. A modified index called ‘ellipsoidness’ was proposed to capture adequately the shape of the 3D particles. Variation of these indices with particle size was studied. Comparison of the 3D true sphericity and the corresponding two-dimensional sphericity indicated that the latter would underestimate sphericity. A modified approach for transforming particle size distribution to constriction size distribution is proposed by capturing the size and shape effects of particles.
Tabatabaiefar, HR & Fatahi, B 2014, 'Idealisation of soil-structure system to determine inelastic seismic response of mid-rise building frames', SOIL DYNAMICS AND EARTHQUAKE ENGINEERING, vol. 66, no. 1, pp. 339-351.
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In this study, a novel and enhanced soilstructure model is developed adopting the direct analysis method using FLAC 2D software to simulate the complex dynamic soil-structure interaction and treat the behaviour of both soil and structure with equal rigour simultaneously. To have a better judgment on the inelastic structural response, three types of mid-rise moment resisting building frames, including 5, 10, and 15 storey buildings are selected in conjunction with three soil types with the shear wave velocities less than 600 m/s, representing soil classes Ce, De and Ee, according to Australian Standards. The above mentioned frames have been analysed under two different boundary conditions: (i) fixed-base (no soil-structure interaction) and (ii) flexible-base (considering soil-structure interaction). The results of the analyses in terms of structural displacements and drifts for the above mentioned boundary conditions have been compared and discussed. It is concluded that considering dynamic soil-structure interaction effects in seismic design of moment resisting building frames resting on soil classes De and Ee is essential.
Tabatabaiefar, SHR, Fatahi, B & Samali, B 2014, 'An empirical relationship to determine lateral seismic response of mid-rise building frames under influence of soil-structure interaction', STRUCTURAL DESIGN OF TALL AND SPECIAL BUILDINGS, vol. 23, no. 7, pp. 526-548.
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n this study, to determine the elastic and inelastic structural responses of mid-rise building frames under the influence of soilstructure interaction, three types of mid-rise moment-resisting building frames, including 5-storey, 10-storey and 15-storey buildings are selected. In addition, three soil types with the shear wave velocities less than 600m/s, representing soil classes Ce, De and Ee according to AS 1170.42007 (Earthquake action in Australia, Australian Standards), having three bedrock depths of 10m, 20m and 30m are adopted. The structural sections are designed after conducting nonlinear time history analysis, on the basis of both elastic method and inelastic procedure considering elastic-perfectly plastic behaviour ofstructural elements. The frame sections are modelled and analysed, employing finite difference method adopting FLAC2D software under two different boundary conditions: (a) fixed base (no soilstructure interaction) and (b) considering soilstructure interaction. Fully nonlinear dynamic analyses under the influence of different earthquake records are conducted, and the results in terms of the maximum lateral displacements and base shears for the above mentioned boundary conditions for both elastic and inelastic behaviours of the structural models are obtained, compared and discussed. With the results, a comprehensive empirical relationship is proposed to determine the lateral displacements of the mid-rise moment-resisting building frames under earthquake and the influence of soilstructure interaction.
Tabatabaiefar, SHR, Fatahi, B & Samali, B 2014, 'Numerical and Experimental Investigations on Seismic Response of Building Frames under Influence of Soil-Structure Interaction', ADVANCES IN STRUCTURAL ENGINEERING, vol. 17, no. 1, pp. 109-130.
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In this study, an enhanced numerical soil-structure model has been developed which treats the behaviour of soil and structure with equal rigour. The proposed numerical soil-structure model has been verified and validated by performing experimental shaking table tests. To achieve this goal, a series of experimental shaking table tests were performed on the physical fixed based (structure directly fixed on top of the shaking table) and flexible base (considering soil and structure) models under the influence of four scaled earthquake acceleration records and the results were measured. Comparing the experimental results with the numerical analysis predictions, it is noted that the numerical predictions and laboratory measurements are in a good agreement. Thus, the proposed numerical soil-structure model is a valid and qualified method of simulation with sufficient accuracy which can be employed for further numerical soil-structure interaction investigation studies. Based on the predicted and observed values of lateral deflections of fixed base and flexible base models, lateral deflections of the flexible base model have noticeably amplified in comparison to the fixed base model. As a result of the lateral deflection amplifications, it is observed that the performance level of the scaled structural model changed significantly which could be safety threatening.
Tehrany, MS, Lee, M-J, Pradhan, B, Jebur, MN & Lee, S 2014, 'Flood susceptibility mapping using integrated bivariate and multivariate statistical models', Environmental Earth Sciences, vol. 72, no. 10, pp. 4001-4015.
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Tehrany, MS, Pradhan, B & Jebur, MN 2014, 'Flood susceptibility mapping using a novel ensemble weights-of-evidence and support vector machine models in GIS', Journal of Hydrology, vol. 512, pp. 332-343.
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Tehrany, MS, Pradhan, B & Jebuv, MN 2014, 'A comparative assessment between object and pixel-based classification approaches for land use/land cover mapping using SPOT 5 imagery', Geocarto International, vol. 29, no. 4, pp. 351-369.
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TENNAKOON, N & INDRARATNA, B 2014, 'Behaviour of clay-fouled ballast under cyclic loading', Géotechnique, vol. 64, no. 6, pp. 502-506.
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Expansion of the rail network in congested coastal Australia compels track construction on soft clayey subgrade, including fine-grained estuarine soils. In such low-lying areas, where the water table is close to the ground surface, the saturated soft subgrade is often subjected to pumping (mud slurry) under the application of cyclic wheel loads, thereby causing fouling of the overlying ballast. This technical note presents the results of a series of large-scale, drained, cyclic, triaxial tests conducted on clay-fouled ballast. The impact of fouling on the stress–strain behaviour, resilient modulus and degradation of ballast is discussed.
Tennakoon, N, Indraratna, B & Rujikiatkamjorn, C 2014, 'Effect of ballast contamination on the behaviour of track substructure', Australian Geomechanics Journal, vol. 49, no. 4, pp. 113-123.
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Ballast contamination by subgrade pumping and coal contamination is understood as major cause of track deterioration in many countries over the world. As contamination clogs the ballast voids, the drainage capacity of the track is compromised. Further, lubrication caused by these fines results in reducing load bearing capacity of the ballast layer. In this study, a series of large scale hydraulic conductivity and triaxial tests were performed to study the influence of contamination of ballast on its drainage and shear strength characteristics. Drainage capacity of the contaminated track under different level of contamination was determined, undertaking a numerical analysis using Seep/W. Shear strength of coal and clay contaminated ballast at different confining pressures were compared. Bearing capacity of contaminated track, using 'foundation under three layers' method was derived and plotted against the degree of contamination. Subsequently, the critical level of contamination by fouling materials such as clay and coal is discussed on the basis of hydraulic conductivity, shear strength and bearing capacity of the ballast.
Torghabeh, A, Rezaee, R, Moussavi-Harami, R, Pradhan, B, Kamali, M & Kadkhodaie-Ilkhchi, A 2014, 'Electrofacies in gas shale from well log data via cluster analysis: A case study of the Perth Basin, Western Australia', Open Geosciences, vol. 6, no. 3, pp. 393-402.
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AbstractIdentifying reservoir electrofacies has an important role in determining hydrocarbon bearing intervals. In this study, electrofacies of the Kockatea Formation in the Perth Basin were determined via cluster analysis. In this method, distance data were initially calculated and then connected spatially by using a linkage function. The dendrogram function was used to extract the cluster tree for formations over the study area. Input logs were sonic log (DT), gamma ray log (GR), resistivity log (IND), and spontaneous potential (SP). A total of 30 reservoir electrofacies were identified within this formation. Integrated geochemical and petrophysics data showed that zones with electrofacies 3, 4, 9, and 10 have potential for shale gas production. In addition, the results showed that cluster analysis is a precise, rapid, and cost-effective method for zoning reservoirs and determining electrofacies in hydrocarbon reservoirs.
Umar, Z, Pradhan, B, Ahmad, A, Jebur, MN & Tehrany, MS 2014, 'Earthquake induced landslide susceptibility mapping using an integrated ensemble frequency ratio and logistic regression models in West Sumatera Province, Indonesia', CATENA, vol. 118, pp. 124-135.
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Vinod, JS, Hyodo, M, Indraratna, B & Miller, R 2014, 'DEM modelling of methane hydrate bearing sand', Australian Geomechanics Journal, vol. 49, no. 4, pp. 175-182.
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Methane gas hydrates are crystalline compounds formed from water and methane under certain pressure and temperature. They are mostly found in marine continental margin sediments and beneath the permafrost and considered as the future non-conventional energy resource. In order to develop innovative techniques for the safe extraction of methane gas from Methane Hydrate (MH) it is important to understand the shear behaviour of methane hydrate bearing sand. It has been reported that the pore scale habits of MH have a significant influence on the shear behaviour of methane hydrate bearing sand. In this paper, an attempt has been made to capture the effect of pore scale habits on the shear behaviour of methane hydrate bearing sand using the Discrete Element Method. Two modelling approaches (i) pore filling, leading to load bearing, and (ii) cementation, bonding of the interparticle contact, have been simulated using PFC3D. A series of triaxial monotonic tests were carried on an assembly of particles for different methane hydrate saturations. Both the approaches have captured, qualitatively, the stress ratio-axial strain behaviour similar to the laboratory experiments. The DEM simulation results highlight that MH saturation has a profound influence on the shear behaviour of hydrate bearing sand. It was shown that the cementation habit closely captures the variation of peak deviator stress with MH saturation similar to the laboratory experiments. Moreover, the evolution of micro-mechanical parameter (e.g. contact force and bond breakage) during shear loading has been presented and discussed.
Wang, SY, Sloan, SW, Sheng, DC, Yang, SQ & Tang, CA 2014, 'Numerical study of failure behaviour of pre-cracked rock specimens under conventional triaxial compression', International Journal of Solids and Structures, vol. 51, no. 5, pp. 1132-1148.
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Xiao, R, Li, J & Shrestha, R 2014, 'Investigations of Vibration Based Condition Assessment of Timber Beams Strengthened with Fiber Reinforced Polymer', ADVANCES IN CIVIL ENGINEERING AND BUILDING MATERIALS III, vol. 831, pp. 53-57.
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In recent years, research trend on structural condition assessments have largely shifted toward utilizing vibration based methods for structural damage detection and evaluation. On the other hand, research and applications on use of fiber reinforce polymer (FRP) on timber for strengthening or repair damaged timber members in various types of timber structures has also become increasingly popular. Although the application of FRP for repair and/or strengthening of structures has been researched for a long time, research on non-destructive assessment or evaluation of the effectiveness and reliability after FRP repairing or strengthening is yet to be carried out. In this paper, the authors made an attempt on investigation of such issue utilizing Damage Index method, which is a robust vibration-based approach for damage detection. The investigation was aiming at localizing and quantifying damage in timber beams and, more importantly evaluating the effectiveness after the damage was repaired. An experimental program was carried out on five laminated veneer lumber (LVL) beams. Various damage scenarios (i.e. severe, medium, light damage) are introduced on these beams and then repaired with carbon fiber reinforced polymer (CFRP). Experimental results indicate that the use of CFRP was effective in repairing the damaged timber beams. Utilizing Damage Index method can accurately detect the damage location. However, the investigation also shows that direct application of the Damage Index for evaluation of the effectiveness of rehabilitation of the damaged timber beam is not satisfactory. Further investigation and modification of the Damage Index method will be carried out in next stage research.
Xu, C, Xu, X, Pourghasemi, HR, Pradhan, B & Iqbal, J 2014, 'Volume, gravitational potential energy reduction, and regional centroid position change in the wake of landslides triggered by the 14 April 2010 Yushu earthquake of China', Arabian Journal of Geosciences, vol. 7, no. 6, pp. 2129-2138.
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Yang, C, Carter, JP & Sheng, D 2014, 'Description of compression behaviour of structured soils and its application', Canadian Geotechnical Journal, vol. 51, no. 8, pp. 921-933.
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One of the most distinct characteristics of structured soils is the nonlinearity in the normal compression lines in a plot of specific volume or voids ratio against logarithmic mean or vertical effective stresses, when compared with reconstituted soils. The change in the compressibility (or compression index) with loading is attributed to structure degradation and is expressed as a function of the plastic straining. A direct description of the compression behaviour of structured soil is then established. The validity of this approach is examined via merely incorporating the newly defined normal compression line into the modified Cam-Clay constitutive model. Comparisons against a series of experiments on different types of soils illustrate the feasibility and advantage of the adopted methodology. The dependence of shear strength on the compression behaviour considered initially in critical-state soil mechanics is reemphasized here for structured soils. Analysis also indicates that the stiffness sensitivity coefficient, Sλ, should be considered together with the traditional strength (or stress) sensitivity coefficient, St (or Sσ), to better characterize the sensitivity of structured soils.
Youssef, AM, Pradhan, B & Maerz, NH 2014, 'Debris flow impact assessment caused by 14 April 2012 rainfall along the Al-Hada Highway, Kingdom of Saudi Arabia using high-resolution satellite imagery', Arabian Journal of Geosciences, vol. 7, no. 7, pp. 2591-2601.
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Yusuf, YA, Pradhan, B & Idrees, MO 2014, 'Spatio-temporal Assessment of Urban Heat Island Effects in Kuala Lumpur Metropolitan City Using Landsat Images', Journal of the Indian Society of Remote Sensing, vol. 42, no. 4, pp. 829-837.
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Zhang, X, Krabbenhoft, K & Sheng, D 2014, 'Particle finite element analysis of the granular column collapse problem', Granular Matter, vol. 16, no. 4, pp. 609-619.
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Zhou, A-N, Sheng, D & Li, J 2014, 'Modelling water retention and volume change behaviours of unsaturated soils in non-isothermal conditions', Computers and Geotechnics, vol. 55, pp. 1-13.
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Ziaei, Z, Pradhan, B & Mansor, SB 2014, 'A rule-based parameter aided with object-based classification approach for extraction of building and roads from WorldView-2 images', Geocarto International, vol. 29, no. 5, pp. 554-569.
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Alamdari, MM, Li, J & Samali, B 1970, 'Damage Localisation Using Symbolic Time Series Approach', Conference Proceedings of the Society for Experimental Mechanics Series, Conference of Society for Experimental Mechanics Series, Springer International Publishing, pp. 109-115.
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© The Society for Experimental Mechanics, Inc. 2014. The objective of this paper is to localise damage in a single or multiple state at early stages of development based on the principles of symbolic dynamics. Symbolic Time Series Analysis (STSA) of noise-contaminated responses is used for feature extraction to detect and localise a gradually evolving deterioration in the structure according to the changes in the statistical behaviour of symbol sequences. The method consists of four primary steps: (1) generating the time series data by a set of measurements over time at evenly spaced locations along the structure; (2) creating the symbol space to generate symbol sequences based on the wavelet transformed version of time series data; (3) developing the symbol probability vectors to achieve anomaly measures; (4) localising damage based on any sudden variation in anomaly measure of two adjacent locations. The method was applied to a clamped–clamped beam subjected to random excitation in presence of 5 % white noise to examine the efficiency and limitations of the method. Simulation results under various damage conditions confirmed the efficiency of the proposed approach for localisation of gradually evolving deterioration in the structure, however, for the future work the method needs to be verified by experimental data.
Al-sharif, AAA, Pradhan, B, Shafri, HZM & Mansor, S 1970, 'Quantitative analysis of urban sprawl in Tripoli using Pearson's Chi-Square statistics and urban expansion intensity index', IOP Conference Series: Earth and Environmental Science, IOP Publishing, pp. 012006-012006.
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Althuwaynee, OF, Pradhan, B & Ahmad, N 1970, 'Landslide susceptibility mapping using decision-tree based CHi-squared automatic interaction detection (CHAID) and Logistic regression (LR) integration', IOP Conference Series: Earth and Environmental Science, IOP Publishing, pp. 012032-012032.
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Aman, SNA, Latif, ZA & Pradhan, B 1970, 'Spatial probabilistic approach on landslide susceptibility assessment from high resolution sensors derived parameters', IOP Conference Series: Earth and Environmental Science, IOP Publishing, pp. 012057-012057.
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Ansari, Y, Kouretzis, GP & Sheng, DC 1970, 'Coupled Finite Element Analysis of Partially Embedded Offshore Pipelines during Vertical Penetration', Applied Mechanics and Materials, Trans Tech Publications, Ltd., pp. 428-433.
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Diverse vertical embedment response is observed for partially embedded pipelines when experimentally tested under similar initial and boundary conditions. Although vertical resistance of pipelines is presented through simple analytical solutions, a number of factors contribute to complications in implementing these theories into practice. The objectives of this research is to provide a more detailed investigation on the vertical embedment for the partially-embedded pipelines (PEPs) using a coupled large deformation finite element (CLDFE) analysis with contact. A modified Cam Clay (MCC) model represents the elastoplastic response of the soil. The model of pipeline embedment investigates the effect of drainage condition on heave forming with respect to rate of penetration. Besides, effect of frictional contact on the heave development and wedging effect is investigated and design-related considerations are proposed. It is shown that depending on the rate of pipeline penetration and soil consolidation rate, the pipeline penetration response can be categorised as undrained, partially drained or fully drained.
Azari, B, Fatahi, B, Khabbaz, H & Vincent, P 1970, 'Elastic Visco-Plastic Behaviour of Soft Soils Improved with Preloading and Vertical Drains', Pavement Performance Monitoring, Modeling, and Management, Geo-Hubei 2014 International Conference on Sustainable Civil Infrastructure, American Society of Civil Engineers, China, pp. 17-24.
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In this study, a numerical solution adopting an elastic visco-plastic model with nonlinear creep function incorporated in the consolidation equations has been developed to investigate the time-dependent behavior of soft soil deposits improved with vertical drains and preloading. The employed elastic visco-plastic model is based on the framework of the modified Cam-Clay model capturing soil creep during excess pore water pressure dissipation. In addition, nonlinear variations of creep strain rate with stress and time and permeability variations during the consolidation process are considered. The developed numerical model is validated against Ska-Edeby test fill with the available long-term settlement and excess pore water pressure monitoring results for the soft clay deposit improved with vertical drains assisted preloading. Practicing engineers can adopt the developed code and guidelines to predict the long-term performance of embankments on soft soil improved using preloading. © ASCE 2014.
Barua, B, Safaei, F & Abolhasan, M 1970, 'Error Exponent of Amplify and Forward Relay Networks in Presence of I.I.D. Interferers', 2014 IEEE 80th Vehicular Technology Conference (VTC2014-Fall), 2014 IEEE 80th Vehicular Technology Conference (VTC Fall), IEEE, Vancouver, Canada.
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© 2014 IEEE. In this paper, we derive the random coding error exponent of amplify-and-forward (AF) relay networks in presence of arbitrary number of independent and identically distributed (i.i.d.) interferers both at the relay and the destination. Multiuser networks are common examples of interference limited networks. We derive the ergodic capacity of the network and present simulation results on the performance of the network where we compare the capacity and error exponent performance of interference limited networks with noise limited networks. Numerical results show that noise limited networks outperform interference limited networks even when only a very few interferers exist in the network.
Bowie, D, Faichney, J & Blumenstein, M 1970, 'Multi-Directional Weighted Interpolation for Wi-Fi Localisation', Advances in Intelligent Systems and Computing, Robot Intelligence Technology and Applications 2: the 2nd International Conference on Robot Intelligence Technology and Applications, Springer International Publishing, pp. 105-112.
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© Springer International Publishing Switzerland 2014. The rise in popularity of unmanned autonomous vehicles (UAV) has created a need for accurate positioning systems. Due to the indoor limitations of the Global Positioning System (GPS), research has focused on other technologies which could be used in this landscape with Wi-Fi localisation emerging as a popular option. When implementing such a system, it is necessary to find an equilibrium between the desired level of final precision, and the time and money spent training the system. We propose Multi-Directional Weighted Interpolation (MDWI), a probabilistic-based weighting mechanism to predict unseen locations. Our results show that MDWI uses half the number of training points whilst increasing accuracy by up to 24%.
Chanda, S, Bu, G, Guan, H, Jo, J, Pal, U, Loo, Y-C & Blumenstein, M 1970, 'Automatic Bridge Crack Detection – A Texture Analysis-Based Approach', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), IAPR TC Workshop on Artificial Neural Networks in Pattern Recognition, Springer Berlin Heidelberg, Montreal, QC, Canada, pp. 193-203.
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© Springer International Publishing Switzerland 2014. To date, identifying cracks in bridges and determining bridge conditions primarily involve manual labour. Bridge inspection by human experts has some drawbacks such as the inability to physically examine all parts of the bridge, sole dependency on the expert knowledge of the bridge inspector. Moreover it requires proper training of the human resource and overall it is not cost effective. This article proposes an automatic bridge inspection approach exploiting wavelet-based image features along with Support Vector Machines for automatic detection of cracks in bridge images. A two-stage approach is followed, where in the first stage a decision is made as whether an image should undergo a pre-processing step (depending on image characteristics), and later in the second stage, wavelet features are extracted from the image using a sliding window-based technique. We obtained an overall accuracy of 92.11% while conducting experiments even on noisy and complex bridge images.
Cooper, CS, Mukunthan, A, Ros, M, Franklin, DR & Abolhasan, M 1970, 'Dynamie environmental fading in urban VANETs.', ICC, IEEE International Conference on Communications, IEEE, Sydney, NSW, Australia, pp. 5641-5646.
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A method of approximating the Rician K-Factor with considerations of the local human-built environment is proposed for urban VANETs. The model is validated experimentally on a busy street in Australia, in the presence and absence of other vehicles. The model is found to accurately predict actual channel measurements in close-range communications scenarios.
Cooper, CS, Ros, M, Safaei, F, Franklin, DR & Abolhasan, M 1970, 'Simulation of Contrasting Clustering Paradigms under an Experimentally-Derived Channel Model.', VTC Fall, IEEE Vehicular Technology Conference, IEEE, Vancouver, BC, pp. 1-6.
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This is a simulation study of weight-based and precedence-based clustering paradigms in VANETs under an experimentally-derived channel model. The study reveals that CH election schemes accounting for driver intention form more stable and long-lived clusters. The results also show that ignoring elements of the VANET channel (such as vehicular shadowing) results in an unreliable comparative analysis of protocol performance.
Dackermann, U, Smith, WA, Li, J & Randall, RB 1970, 'On the use of the cepstrum and artificial neural networks to identify structural mass changes from response-only measurements', PROCEEDINGS OF INTERNATIONAL CONFERENCE ON NOISE AND VIBRATION ENGINEERING (ISMA2014) AND INTERNATIONAL CONFERENCE ON UNCERTAINTY IN STRUCTURAL DYNAMICS (USD2014), International Conference on Noise and Vibration Engineering, KU Leuven - Departement Werktuigkunde, Leuven, Belgium, pp. 3739-3750.
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This paper presents a damage identification technique based on response-only data utilising cepstrum analysis and artificial neural networks (ANNs) for the identification of added mass in a two-storey framed structure. The proposed technique applies cepstrum-based operational modal analysis (OMA) for the regeneration of frequency response functions (FRFs), and added mass is detected through the combined use of principal component analysis (PCA) for data compression and ANNs for feature extraction and pattern recognition. In particular, different treatments of the zeros in the curve-fitting of the transfer function cepstrum are investigated to improve the automation potential of the method for application in continuous online structural health monitoring (SHM). The proposed technique is validated on a laboratory structure tested on a large-scale shake table with ambient base loading. The results of the investigation show that the method is effective in identifying added mass based on response-only measurements.
Dadras, M, Shafri, HZM, Ahmad, N, Pradhan, B & Safarpour, S 1970, 'Six decades of urban growth using remote sensing and GIS in the city of Bandar Abbas, Iran', IOP Conference Series: Earth and Environmental Science, IOP Publishing, pp. 012007-012007.
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Das, A, Pal, U, Ferrer Ballester, MA & Blumenstein, M 1970, 'A new efficient and adaptive sclera recognition system', 2014 IEEE Symposium on Computational Intelligence in Biometrics and Identity Management (CIBIM), 2014 IEEE Symposium on Computational Intelligence in Biometrics and Identity Management (CIBIM), IEEE, Orlando, USA, pp. 1-8.
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© 2014 IEEE. In this paper an efficient and adaptive biometric sclera recognition and verification system is proposed. Sclera segmentation was performed by Fuzzy C-means clustering. Since the sclera vessels are not prominent, in order to make them clearly visible image enhancement was required. Adaptive histogram equalization, followed by a bank of Discrete Meyer Wavelet was used to enhance the sclera vessel patterns. Feature extraction was performed by, Dense Local Directional Pattern (D-LDP). D-LDP patch descriptors of each training image are used to form a bag of features; further Spatial Pyramid Matching was used to produce the final training model. Support Vector Machines (SVMs) are used for classification. The UBIRIS version 1 dataset was used here for experimentation of the proposed system. To investigate regarding sclera patterns adaptively with respect to change in environmental condition, population, data accruing technique and time span two different session of the mention dataset are utilized. The images in two sessions are different in acquiring technique, representation, number of individual and they were captured in a gap of two weeks. An encouraging Equal Error Rate (EER) of 3.95% was achieved in the above mention investigation.
Das, A, Pal, U, Ferrer Ballester, MA & Blumenstein, M 1970, 'A new wrist vein biometric system', 2014 IEEE Symposium on Computational Intelligence in Biometrics and Identity Management (CIBIM), 2014 IEEE Symposium on Computational Intelligence in Biometrics and Identity Management (CIBIM), IEEE, Orlando, USA, pp. 68-75.
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© 2014 IEEE. In this piece of work a wrist vein pattern recognition and verification system is proposed. Here the wrist vein images from the PUT database were used, which were acquired in visible spectrum. The vein image only highlights the vein pattern area so, segmentation was not required. Since the wrist's veins are not prominent, image enhancement was performed. An Adaptive Histogram Equalization and Discrete Meyer Wavelet were used to enhance the vessel patterns. For feature extraction, the vein pattern is characterized with Dense Local Binary Pattern (D-LBP). D-LBP patch descriptors of each training image are used to form a bag of features, which was used to produce the training model. Support Vector Machines (SVMs) were used for classification. An encouraging Equal Error Rate (EER) of 0.79% was achieved in our experiments.
Das, A, Pal, U, Ferrer Ballester, MA & Blumenstein, M 1970, 'Fuzzy logic based selera recognition', 2014 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE), 2014 IEEE International Conference on Fuzzy Systems (FUZZ-IEEE), IEEE, China, pp. 561-568.
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© 2014 IEEE. In this paper a selera recognition and validation system is proposed. Here selera segmentation was performed by Fuzzy logic-based clustering. Since the selera vessels are not prominent, image enhancement was required. A Fuzzy logic-based Brightness Preserving Dynamic Fuzzy Histogram Equalization and discrete Meyer wavelet was used to enhance the vessel patterns. For feature extraction, the Dense Local Binary Pattern (D-LBP) was used. D-LBP patch descriptors of each training image are used to form a bag of features, which is used to produce the training model. Support Vector Machines (SVMs) are used for classification. The UBIRIS version 1 dataset is used here for experimentation. An encouraging Equal Error Rate (EER) of 4.31% was achieved in our experiments.
Das, A, Pal, U, Ferrer Ballester, MA & Blumenstein, M 1970, 'Multi-angle based lively sclera biometrics at a distance', 2014 IEEE Symposium on Computational Intelligence in Biometrics and Identity Management (CIBIM), 2014 IEEE Symposium on Computational Intelligence in Biometrics and Identity Management (CIBIM), IEEE, USA, pp. 22-29.
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© 2014 IEEE. This piece of work proposes a liveliness based sclera eye biometric, validation and recognition technique at a distance. The images in this work are acquired by a digital camera in the visible spectrum at varying distance of about 1 meter from the individual. Each individual during registration as well as validation is asked to look straight and move their eye ball up, left and right keeping their face straight to incorporate liveliness of the data. At first the image is divided vertically into two halves and the eyes are detected in each half of the face image that is captured, by locating the eye ball by a Circular Hough Transform. Then the eye image is cropped out automatically using the radius of the iris. Next a C-means-based segmentation is used for sclera segmentation followed by vessel enhancement by the adaptive histogram equalization and Haar filtering. The feature extraction was performed by patch-based Dense-LDP (Linear Directive Pattern). Furthermore each training image is used to form a bag of features, which is used to produce the training model. Each of the images of the different poses is combined at the feature level and the image level to obtain higher accuracy and to incorporate liveliness. The fusion that produces the best result is considered. Support Vector Machines (SVMs) are used for classification. Here images from 82 individuals (both left and right eye i.e. 164 different eyes) are used and an appreciable Equal Error Rate of 0.52% is achieved in this work.
Fatahi, B, Hokmabadi, AS & Samali, B 1970, 'Seismic Performance-Based Design for Tall Buildings Considering Soil-Pile-Structure Interaction', Advances in Soil Dynamics and Foundation Engineering, Geo-Shanghai 2014, American Society of Civil Engineers, Shanghai, pp. 333-342.
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Soil-Structure Interaction (SSI) plays a significant role in seismic response of the structures by altering the dynamic properties of the system and increasing the lateral deflection which in turn could change the performance level of structures. In this study, in order to experimentally investigate the influence of different types of foundations on SSI phenomena, a series of shaking table tests has been conducted considering four different cases, namely: (i) fixed-base structure representing the situation excluding the soil-structure interaction; (ii) structure supported by shallow foundation on soft soil; and (iii) structure supported by floating pile foundation in soft soil, and (iv) structure supported by end-bearing pile foundation in soft soil. Benchmark earthquakes including the 1995 Kobe, the 1994 Northridge, the 1968 Hachinohe, and the 1940 El Centro earthquakes are adopted. Results indicate that presence and type of pile foundations change the dynamic characteristics and behaviour of the superstructure which should be considered in predicting the damage level of structural and non-structural elements.
Fazel, SAA, Blumenstein, M, Mirfenderesk, H & Tomlinson, R 1970, 'Estuarine flood modelling using artificial neural networks', 2014 International Joint Conference on Neural Networks (IJCNN), 2014 International Joint Conference on Neural Networks (IJCNN), IEEE, Beijing, China, pp. 631-637.
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Prediction of water levels at estuaries poses a significant challenge for modelling of floods due to the influence of tidal effects. In this study, a two-stage forecasting system is proposed. In the first stage, the tidal portion of the available records is used to develop a tidal prediction system. The predictions of the first stage are used for flood modelling in the second. Experimental results suggest that the proposed flood modelling approach is advantageous for forecasting flood levels with more than 1 hour lead times.
Fazel, SAA, Mirfenderesk, H, Blumenstein, M & Tomlinson, R 1970, 'Application of neural network to flood forecasting an examination of model sensitivity to rainfall assumptions', Proceedings - 7th International Congress on Environmental Modelling and Software: Bold Visions for Environmental Modeling, iEMSs 2014, Meeting of the International Environmental Modelling and Software Society, iEMSs, USA, pp. 742-749.
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This paper describes the development of a back-propagation Neural Network model for predicting flood and its application to a short response catchment. Common operational flood forecasting is based on traditional physically based and conceptual methods. These methods, despite being based on robust physical laws, have limitations. Data-driven models are plausible alternatives to physically based methods for certain flood forecasting applications. However, there is still a need for further demonstration of their ability in flood forecasting in order to build enough confidence for their application in practice. Among the aims of developing forecasting models, is utilizing them as a decision support system. To ensure applicability of the system for real-world application, limitations of the model should be outlined. Initial simulations conducted on a small-response time catchment outlined sensitivity of the accuracy of the model to rainfall and the way it is addressed. In this study, uncertainties associated with unseen portion of rainfall at the time that the actual forecasting is carried out, during real-world flood event are emulated. Four scenarios are considered for this study, rainfall is assumed known, rainfall is naively predicted, rainfall is treated as hidden variable and rainfall is predicted using axillary ANN. The study shows that a proposed ANN is adequately skilled for short-term flood predictions; however variability in rainfall within span of few hours limits reliability of predictions as time horizon increases. In addition the study proposes several directions that may improve the forecasts despite inherit limitations. In particular, subsequent to qualitative performance analysis, it was observed that optimization goal defined for ANN, Root Mean Square Error (RMSE) is not fully aligned with purpose of a decision support system and hence can be pursued as a potential research direction.
Gandhi, S, Sankaran, S, Er, M, Orr, K & Khabbaz, H 1970, 'Developing Technology-Assisted Multi-Disciplinary Learning Strategies', Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 31st International Symposium on Automation and Robotics in Construction, International Association for Automation and Robotics in Construction (IAARC), Sydney, pp. 346-353.
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The construction industry is multi-disciplinary and collaborative in nature. Project managers are expected to understand the relations, roles and responsibilities in this collaborative working environment. Construction project managers need to be equipped with skills to process and understand the principles of interdisciplinary working. In order to keep pace with industry requirements, it is necessary for universities to teach subjects in tertiary education courses that educate and motivate construction students towards interdisciplinary working. This paper is based on a research project aimed at understanding opportunities and challenges for introducing subjects that require students from different disciplines to work together on an integrated project. In order to teach interdisciplinary working principles to project management students, a new post-graduate subject, Integrated Project Delivery, was introduced in the Master of Project Management at the University of Technology Sydney (UTS) as part of a construction sub-major. The subject was designed and teaching materials prepared based on inputs from architecture, engineering and construction management academics. In the teaching of the subject, interdisciplinary student teams were formed based on educational background and professional experience. An (pedagogical) action research approach was adopted to study the challenges and benefits of new ways of learning in line with the UTS learning strategies being adopted by academics. The main finding of this research concluded that project-based learning is very valuable to both students and industry alike as it promotes working on a live project enthusiastically and gaining industry experience in new ways of working adopted by industry. Working in multi-disciplinary teams requires students to respect the other team participants from different backgrounds, inculcating values of team spirit and discouraging adversarial behaviours. Furthermore this research ...
Gardner, AP, Willey, K, Vessalas, K & Li, J 1970, 'Experiences with flipped learning in subjects in consecutive stages of aCivil Engineering programme', Proceedings of the 25th Annual Conference of the Australasian Association for Engineering Education, AAEE - Annual Conference of Australasian Association for Engineering Education, School of Engineering & Advanced Technology, Massey University, Wellington, NZ.
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CONTEXT Flipped learning is an instructional approach which allows instructors the opportunity to use a blending of online and face to face learning activities. The main affordance of flipped learning is the opportunity to free up class time to allow students and instructors to engage in collaborative learning activities designed to consolidate and deepen conceptual understanding of the subject material. Research has shown that participating in flipped instruction can change the way students approach their studies and improve motivation.PURPOSE OR GOALWe are interested in students’ experience of the flipped environment, particularly their expectations of a learning environment, and the level of responsibility they take for their own learning. The purpose of this analysis is to create a baseline against which future instances of flipped learning can be compared.APPROACH Student perceptions of flipped instruction were investigated through survey responses and observations of students in a first year subject (Engineering Mechanics) a second year subject (Engineering Computations) and a third year subject (Construction Materials) in a Civil Engineering degree programme. In particular, students were asked to explain the impact of the flipped activities on their learning experience including any changes in how they approach their studies or managed their time.OUTCOMES Most students in each of the three subjects agreed that they ‘liked’ flipped instruction compared to the traditional lecture format. The majority of students in each subject also agreed that it is reasonable to expect students to prepare before attending a face to face session. However, some students made strong negative comments demonstrating how the flipped environment did not meet their expectations of how learning should be organised. This study suggests that students in the second and third year subjects were not necessarily showing signs of better self-regulation and time man...
Ghanavati, M, Wong, RK, Chen, F, Wang, Y & Perng, C-S 1970, 'An Effective Integrated Method for Learning Big Imbalanced Data', 2014 IEEE International Congress on Big Data, 2014 IEEE International Congress on Big Data (BigData Congress), IEEE, Anchorage, AK, pp. 691-698.
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Gu, X, Li, J & Li, Y 1970, 'Innovative semi-active storey isolation system utilising novel magnetorheological elastomer base isolators', Proceedings of the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 925-930.
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Seismic base isolation has been a widely adopted technique for earthquake protection of civil infrastructures. As the technology matures, new innovative designs of the base isolation systems become increasingly attractive to researchers, especially storey base isolation systems due to its design flexibility and better performance for seismic protection. Moreover, considering the unpredictable and diverse nature of earthquakes, the conventional base isolation systems have reached their limit due to their inherent passive nature which is incapable to adjust their isolation frequencies according to the characteristics of the earthquakes. A recent advance on the development of an adaptive magneto-rheological elastomer (MRE) base isolator provides an opportunity for the research and development on new adaptive base isolation systems. In this paper, an innovative semi-active storey isolation system utilising the novel magneto-rheological elastomer base isolator has been proposed. The proposed isolation system design incorporates adaptive magneto-rheological elastomer isolators under each storey of the structure instead of being only installed beneath of the entire structure. Such innovative system allows high authority semiactive control of storey responses by instantly changing stiffness of the isolator. Extensive simulation has been conducted to investigate such system using 5-storey international benchmark model under four benchmark earthquakes.
Guma Biro Turk, K & Pradhan, B 1970, 'Exploitation of GeoEye-1 Data for Land Use/Land Cover Analysis Using Object-Based Image Analysis in the Eastern Nile Basin of Sudan', 40th COSPAR Scientific Assembly.
Halkon, B, Mitchell, S, Payne, T & Carbo, J 1970, 'Biomechanical Measurements of Human Impacts in Basketball', Procedia Engineering, 10th Conference of the International-Sports-Engineering-Association, Elsevier BV, Sheffield Hallam Univ, Sheffield, ENGLAND, pp. 214-219.
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Despite significant advances in materials and manufacturing techniques applied to sports protective equipment in recent years, sports injuries due to impact, contusions in particular, continue to occur. In this paper, a test methodology aimed at collecting data from laboratory-simulated human-on-human impacts in Basketball is presented. The study was executed in three stages with data being collected from: i) human on instrumented bag; ii) impactor on instrumented bag and iii) impactor on instrumented human impacts. In all cases, high-speed video and/or kinematic motion data capture systems were used to obtain parameters such as inbound/outbound velocities, contact durations while resistive ink technology pressure sensing films were used to estimate parameters such as pressure distributions, peak pressures, contact areas, impact forces. Elite-level athletes were used in all human trials to ensure that impact techniques and levels representative of the elite game were obtained and that tolerance to impacts was similarly representative. Two common strikes were simulated: knee on thigh and elbow on rib/torso. Five participants were used to collect the human-on-bag data while 12 participants were used to collect the impactor-on-human data. Between three and five impacts per scenario were performed to enable noise averaging and, importantly, likely injurycausing outlier capture. © 2014 Published by Elsevier Ltd.
Harfield, P, Halkon, B, Mitchell, S, Phillips, I & May, A 1970, 'A Novel, Real-time Biomechanical Feedback System for Use in Rowing', Procedia Engineering, 10th Conference of the International-Sports-Engineering-Association, Elsevier BV, Sheffield Hallam Univ, Sheffield, ENGLAND, pp. 126-131.
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Biomechanical feedback in water-based rowing is traditionally presented as paper reports or video overlaid with data once a session has been completed. Research into the provision of extrinsic feedback in sport suggests that real-time feedback can lead to skill acquisition and, when appropriately applied, lead to skill retention during competition and therefore a positive performance outcome. This paper presents a novel system architecture that delivers real-time feedback using commercially available off-the-shelf components. The development of a rowing specific system to test a range of feedback strategies is presented, including fading feedback, mixing feedback modalities and varying of the frequency and timing of feedback. MoSync, a cross-platform smartphone development language, was used to write the client application while the server was written as an embedded application in C and Lua that ran on top of the OpenWrt open-source router operating system. Data was transmitted wirelessly across a Wi-Fi network. A human-centred design process was led by a group of highperformance athletes and coaches and the system was shown to deliver data to up to 10 clients simultaneously. Future research will investigate the efficacy of a variety of different feedback strategies to rowers. © 2014 Published by Elsevier Ltd.
He, X & Liang, D 1970, 'SPH study on the influence of shear-rate dependent effects on the flow behaviour of dry granular assemblies', Proceedings of the 11th (2014) Pacific/Asia Offshore Mechanics Symposium, PACOMS 2014, pp. 198-204.
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Phenomenally, the loose soil behaves like a 'frictional material' in most circumstance, so Mohr-coulomb type models are adopted in the modeling. However, these models generally do not consider the shear-rate dependent effect of the MohrCoulomb friction angle. This paper reports on an application of the incompressible Smooth Particle Hydrodynamic method to the dynamics of the dry granular assemblies. The traditional model with a constant friction angle is compared with the modified Mohr-Coulomb model with a shear-rate dependent friction angle, by comparing their predicted runout of dry granular columns.
Heitor, A, Indraratna, B & Rujikiatkamjorn, C 1970, 'Aspects Related to the Small Strain Shear Modulus Behavior of Compacted Soils Subjected to Wetting and Drying', Geo-Congress 2014 Technical Papers, Geo-Congress 2014, American Society of Civil Engineers, pp. 1433-1442.
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The dynamic properties of a soil are routinely investigated to describe its engineering behavior under repeated loading. Although the effect of suction on the dynamic response of soils is significant, there have been limited studies in which the post-compacted changes in suction induced by wetting and drying cycles have been considered. In this paper, aspects related to the dynamic properties with special reference to the small strain shear modulus of compacted soils subjected to wetting and drying are described. Further evidence on the dynamic response in terms of small strain shear modulus (G0) of a compacted soil subjected to wetting-drying is presented and novel insights into small strain behavior in multiple cycles of wetting and drying are shown. Particular emphasis is placed on the hysteric behavior and its dependence on the suction history. The results not only confirm the importance of the current suction ratio (or CSR), but also suggest that subsequent wetting-drying cycles further induce hysteretic changes in relation to the small strain shear modulus, particularly when following the wetting paths. © 2014 American Society of Civil Engineers.
Heitor, A, Indraratna, B & Rujikiatkamjorn, C 1970, 'Role of the compaction energy level on the small strain stiffness of a silty sand soil subjected to wetting and drying', UNSATURATED SOILS: RESEARCH & APPLICATIONS, VOLS 1 AND 2, 6th International Conference on Unsaturated Soils (UNSAT), CRC Press, Sydney, AUSTRALIA, pp. 749-754.
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Ho, L, Fatahi, B & Khabbaz, H 1970, 'Analytical solution for one-dimensional consolidation of unsaturated soil deposit subjected to step loading', UNSATURATED SOILS: RESEARCH & APPLICATIONS, VOLS 1 AND 2, International conference on Unsaturated Soils, Taylor & Francis Group, Sydney, pp. 1763-1769.
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This paper discusses a simple yet precise analytical solution for one-dimensional (1-D) consolidation of an unsaturated soil deposit subjected to a step loading. This solution is derived from nonlinear governing equations of flow using eigenfunction expansions and Laplace transform techniques. In addition, the mathematical development adopts one-way drainage condition for the unsaturated soil, in which the top boundary is permeable to the air and water phases whereas the base is impervious to these phases. Eigenfunctions and eigenvalues are parts of the general solution and can be obtained based on the proposed drainage boundary condition. Furthermore, uniformly distributed initial pore pressures can be used to determine the initial generalised Fourier coefficients. The Laplace transform method is adopted to solve the first-order differential equations. Once the equations with transformed domain are obtained, the final solutions, which are proposed to be functions of time (t) and depth (z), can be achieved by taking an inverse Laplace transform. A worked example is provided to present the consolidation characteristics of unsaturated soils based on the proposed solution. Significance of air to water permeability ratio on the excess pore-water and pore-air pressure dissipation and compression is investigated and discussed. © 2014 Taylor & Francis Group.
Ho, L, Fatahi, B & Khabbaz, H 1970, 'One-Dimensional Consolidation of Unsaturated Soil Deposit with Various Initial Conditions', Soil Behavior and Geomechanics, Geo-Shanghai 2014, American Society of Civil Engineers, Shanghai, pp. 145-155.
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This study presents a novel analytical solution for one-dimensional (1-D) consolidation for unsaturated soils using the Eigen function expansion method to solve inhomogeneous governing equations of air and water phases. Eigen functions and eigen values are parts of the general solution and can be obtained based on the proposed boundary condition. Additionally, the Laplace transform method is adopted to solve the first-order differential equations. Once all equations with transformed domain are obtained, the final solutions, which are proposed to be functions of time and depth, can be achieved by taking an inverse Laplace transform. The mathematical procedure accentuates a non-uniform initial condition in which initial excess pore pressures are linearly decreasing with depth. Dimensionless parameters a and w that control the gradients of distributions of initial excess pore-air and pore-water pressures, respectively, are introduced in this paper. A worked example is provided to investigate effects of a and w on the consolidation behaviour of unsaturated soils. © 2014 American Society of Civil Engineers.
Indraratna, B, Nimbalkar, S & Rujikiatkamjorn, C 1970, 'Preface', Transportation Geotechnics, Elsevier BV, pp. 145-146.
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Indraratna, B, Rujikiatkamjorn, C & Balasubramaniam, AS 1970, 'Consolidation of Estuarine Marine Clays for Coastal Reclamation Using Vacuum and Surcharge Loading', From Soil Behavior Fundamentals to Innovations in Geotechnical Engineering, Geo-Congress 2014, American Society of Civil Engineers, pp. 358-369.
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Soft clays in coastal areas have low shear strength and high compressibility. Consequently, certain construction activities for infrastructure developments in these deposits often pose geotechnical problems due to large time-dependent settlements and lateral movements. Ground improvement techniques are adopted in such terrains to reduce the water content of soft clays by preloading with surcharge fill over vertical drains. Depending on the magnitude of the surcharge load used, substantial immediate settlement with lateral movements can take place during preloading, leading to undrained stability problems in various parts of the clay foundation. Therefore, the use of vacuum-assisted preloading has now become a popular method in ground improvement works where substantial loads need to be carried out to meet a desired rate of settlement and mitigate undrained failure by controlling lateral displacements. To assist the vacuum propagation to significant depths, vertical drains are used in tandem at the Port of Brisbane, Australia, and vacuum-assisted surcharge preloading and conventional surcharge preloading schemes were adopted to reduce the consolidation time and long-term settlement in soft Holocene clays in 2009. It is shown that a combined vacuum surcharge loading system with a standard surcharge fill highlights the obvious benefits of vacuum consolidation in reducing long-term settlement and enhanced stability. © 2014 American Society of Civil Engineers.
Indraratna, B, Rujikiatkamjorn, C & Nimbalkar, S 1970, 'Ground Improvement for Rail, Port and Road Infrastructure--From Theory to Practice', Ground Improvement and Geosynthetics, Geo-Shanghai 2014, American Society of Civil Engineers, pp. 1-19.
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The transportation infrastructure in coastal regions of Australia has been expanded in recent years due to high population density and increased traffic volume. Such expansions require the application of ground improvement techniques to improve performance and sustainability of the infrastructure. In this paper, innovative ground improvement techniques applicable to railway embankments, port reclamation and embankment fills are discussed. For ballasted rail tracks, the performance of different types of geosynthetics for improving the stability and drainage of railway tracks under high cyclic loading is investigated. Instrumented tracks were conducted to measure the in-situ stresses and deformations of ballast at Bulli, New South Wales (NSW), Australia. Furthermore, stabilization of soft formation soils underneath rail tracks using prefabricated vertical drains (PVDs) is also studied through finite element analyses and field measurements at Sandgate. The innovative use of the mixtures of coal wash (CW) and steel furnace slag (SFS) as the reclamation fill is demonstrated through laboratory and field investigations at the Outer Harbor extension of Port Kembla in Wollongong, NSW. The optimum CW-SFS mixtures that may meet most of the geotechnical specifications are proposed to be used as an effective structural fill. Finally, the design of the combined vacuum and surcharge fill system and the construction of the road embankment are described using a case study from the Pacific Highway upgrade project. Field data are presented and interpreted to demonstrate how the embankments performed during construction in both vacuum and non-vacuum areas. © ASCE 2014.
Indraratna, B, Rujikiatkamjorn, C, Nguyen, VT & Raut, A 1970, 'Analytical Solutions for Filtration Process Based on the Constriction Size Concept', Geo-Congress 2014 Technical Papers, Geo-Congress 2014, American Society of Civil Engineers, pp. 999-1006.
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In this paper, an analytical model was proposed to describe the filtration process applicable to a base soil-filter system. The Navier-Stokes equation for porous media was used to capture the hydrodynamic behavior, while numerically a new algorithm has been proposed to solve the Navier-Stokes equation in nonlinear form. The various mixtures of base particles eroded and water flow within the system was computed using the work-energy principle incorporating the constriction size of the filter. The model can assess the filtration process through the flow rate, and the accumulation and erosion of base soil within the filter. By discretizing the base soil and filter domains into discrete elements, the model can predict the time-dependent particle gradation of the filter for each element. Laboratory tests reported in other studies and those conducted by the authors have verified the validity of the model in relation to other available models. © 2014 American Society of Civil Engineers.
Indraratna, B, Rujikiatkamjorn, C, Ni, J & Carter, J 1970, 'Application of geosynthetic vertical drains under cyclic loads for track stabilization', Computer Methods and Recent Advances in Geomechanics, Computer Methods and Recent Advances in Geomechanics, CRC Press, KYOTO, JAPAN, pp. 1157-1162.
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Jozi, BJ, Dackermann, U, Braun, RB, Li, JL & Samali, BS 1970, 'Application and improvement of conventional stress-wave-based non-destructive testing methods for the condition assessment of in-service timber utility poles', Proceedings of the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 1197-1202.
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Timber utility poles represent a significant part of Australia’s infrastructure for power distribution andcommunication networks. Due to their advanced age, significant efforts are undertaken to preventutility lines from failure. However, the lack of reliable tools for assessing the condition of in-servicepoles seriously jeopardizes the maintenance and asset management. Non-destructive testing (NDT)methods based on stress wave propagation can potentially offer simple and cost-effective tools for thecondition assessment of in-service timber poles. Based on the impact direction and location, mainlytwo wave types can be excited in a pole, i.e. longitudinal and bending waves. A conventional stresswave-based method that analyses longitudinal waves is the Sonic Echo (SE) method; and a typicalsignal processing method for the analysis of bending waves (BW) is the Short Kernel Method (SKM).In this paper, firstly, the application of the conventional SE method and the BW method with SKMdata analysis is investigated for the condition assessment of timber poles from a signal processingperspective. Secondly, to improve limitations of the current methods, the application of a multisensorsarray is proposed for more reliable and accurate results. The new method is validated onnumerical data of a timber pole modelled with both isotropic and orthotropic material properties.
Kalhori, H, Ye, L, Mustapha, S & Li, J 1970, 'Impact force reconstruction on a concrete deck using a deconvolution approach', 8th Australasian Congress on Applied Mechanics, ACAM 2014, as Part of Engineers Australia Convention 2014, Australasian Congress on Applied Mechanics, Informit, Melbourne, Australia, pp. 763-771.
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In this study, impact force history applied to a steel-reinforced concrete deck has been reconstructed based on vibration response signals collected at random positions from the impact location. A deconvolution technique in time domain utilizing the responses recorded, from piezoelectric (PZT) sensors and accelerometers are used to reconstruct the impact force. As the deconvolution is an ill-conditioned inverse problem, the truncated singular value decomposition (TSVD) and the Tikhonov regularization are used to regularize the problem. The effect of different attachment methods of the PZTs/accelerometers on the structure is investigated including the use of Blu-tack and the 5-minnutes Araldite. It is found that with the use of the Blu-tack, the reconstructed force is not predicted precisely which can be attributed to the nonlinear behaviour of the Blu-tack. In addition, the effect of the location of the measurement point on quality of reconstructed impact force is investigated. It is found that when the measurement location is very close to the impact site, there is no need to use the regularization techniques and the pseudo-inverse method can provide acceptable results.
Karimullah Hussaini, SK, Indraratna, B & Vinod, JS 1970, 'An Experimental Investigation on the Deformation and Degradation Behaviour of Geogrid-Reinforced Ballast', Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance, The Second International Conference on Railway Technology: Research, Development and Maintenance, Civil-Comp Press.
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© Civil-Comp Press, 2014. Railroad ballast, owing to its unbounded granular nature, spreads laterally when subjected to large vertical axle loads, which influences the track stability. In this view, large-scale cyclic tests have been conducted on ballast to explore the role of geogrid in controlling the lateral deformation of ballast and hence improving the track performance. Fresh latite ballast having a mean particle size of 35 mm and geogrids with different aperture sizes was used for the investigations. Tests were conducted using a modified process simulation test (MPST) apparatus at a loading frequency of 20 Hz, with geogrid placed at the subballast-ballast interface and within the ballast. The laboratory experimental results indicate that the geogrid arrests the lateral spreading of ballast, reduces the extent of permanent vertical settlement and minimises the particle breakage under high-frequency cyclic loading. However, the improvement in track performance is directly influenced by the effectiveness of the ballast-geogrid interface. It is shown that the higher the shear strength at the ballast-geogrid interface, the lower is the deformation and degradation of ballast. In addition, the geogrid also reduces the extent of vertical stress in the subgrade soil. These test results highlight the role of geogrid in stabilising the ballast thus encouraging its use as track reinforcement in railway applications.
Khabbaz, H & Fatahi, B 1970, 'A critical and comparative review of ballasted and slab tracks: Where are we heading?', Civil-Comp Proceedings, International Conference on Railway Technology: Research, Development and Maintenance, Civil-Comp Press, France.
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High speed rail (HSR) is currently an experienced rail transport system, which has been recognised to deliver real benefits against road and air transportation. This paper highlights the geotechnical problems involved with HSR on ballasted tracks and how slab tracks can overcome these issues. There are many geotechnical issues surrounding the performance of high-speed trains on ballasted railway tracks. A number of noticeable issues include critical velocity effects, track vibration and large settlement due to ballast degradation. In comparison to ballasted tracks, slab tracks reduce the construction height, reduce track maintenance, reduce the wear down of rails, provide better riding comfort at high speeds, provide higher availability, reduce vibration and secondary airborne noises, improve load distribution, provide high lateral and longitudinal track stability and eliminate problems with vegetation control, which is essential for a rail track structure. Accordingly, many railway experts have concluded that it is time to say goodbye to the ballasted tracks. Based on several case studies, laboratory results and validated numerical analysis, this paper clearly elaborates that if ballasted tracks are designed and stabilised properly, they will be cost effective and can well-perform under dynamic loads of high speed rails.
Khabbaz, H, Lin, EX & Fatahi, B 1970, 'A Parametric Study on Shoring Structures with Multi-Row Anchors in Layered Soil', Earthwork Project Management, Slope Stability Analysis, and Wave-Based Testing Techniques, Geo-Hubei 2014 International Conference on Sustainable Civil Infrastructure, American Society of Civil Engineers, China, pp. 81-88.
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This paper examines two numerical methods commonly used in shoring design, namely the beams on elastic foundation method using WALLAP and the finite element method (FEM) using PLAXIS. Numerous design parameters are also investigated to study the effects of the parametric variations on each method. The shoring model analyzed in this study is based on a deep excavation project in the Sydney central business district. One of the significant findings of this study was that the results obtained from both WALLAP and PLAXIS showed marginal numerical errors, which, in turn, need to be examined closely. Generally, the beams on elastic foundation method are more conservative than the FEM. In comparison with the FEM, the soil modulus has more significant effects than the shear strength parameters in the beams on elastic foundation method. Moreover, the resulting shear forces, bending moments, and lateral displacements of the shoring are less sensitive to the variation of the soil friction angle than the cohesion. The findings of this study can be taken into consideration by practicing civil engineers when designing appropriate shoring systems in urban areas. © ASCE 2014.
Kouretzis, GP, Sheng, DC & Wang, D 1970, 'Numerical Simulation of CPT Cone Penetration in Sand', Applied Mechanics and Materials, Trans Tech Publications, Ltd., pp. 416-421.
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Numerical simulation of cone penetration in sand is performed by means of a computationally efficient critical state model implemented in an explicit-integration finite element code. Its main advantage, compared to other published studies employing simpler soil models such as the Drucker-Prager, is that sand compressibility can be described with a single set of model parameters, irrespective of the stress level and the sand relative density. Calibration of the constitutive model is based on back-analysis of published centrifuge tests results, and consequently the predictions of the numerical methodology are compared against independent tests. Additional analyses are performed for proposing a new simplified formula to correlate the cone penetration resistance with the in situ sand relative density.
Kunwar, R, Pal, U & Blumenstein, M 1970, 'Semi-supervised Online Bayesian Network Learner for Handwritten Characters Recognition', 2014 22nd International Conference on Pattern Recognition, 2014 22nd International Conference on Pattern Recognition (ICPR), IEEE, Stockholm, Sweden, pp. 3104-3109.
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© 2014 IEEE. This work addresses the problem of creating a Bayesian Network based online semi-supervised handwritten character recognisor, which learns continuously over time to make a adaptable recognisor. The proposed method makes learning possible from a continuous inflow of a potentially unlimited amount of data without the requirement for storage. It highlights the use of unlabelled data for boosting the accuracy, especially when labelled data is scarce and expensive unlike unlabelled data. An algorithm is introduced to perform semi-supervised learning based on the combination of novel online ensemble of the Randomized Bayesian network classifiers and a novel online variant of the Expectation Maximization (EM) algorithm. We make use of a novel varying weighting factor to modulate the contribution of unlabelled data. Proposed method was evaluated using online handwritten Tamil characters from the IWFHR 2006 competition dataset. The accuracy obtained was comparable to the state of the art batch learning methods like HMM and SVMs.
Le, TM, Fatahi, B & Khabbaz, H 1970, 'Numerical solution to predict visco-plastic model parameters of soft clay during excess pore water pressure dissipation', NUMERICAL METHODS IN GEOTECHNICAL ENGINEERING, VOL 1, European Conference on Numerical Methods in Geotechnical Engineering, Taylor and Francis Group, Delft, the Netherlands, pp. 175-180.
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The elastic visco-plastic model with non-linear creep function may describe the long termbehavior of clayey soils more accurately. However, it is a challenging task to determine the parameters of the non-linear creep function using conventional oedometer data. This paper presents a numerical method to determine several model parameters simultaneously, while adopting consolidation data during excess pore water pressure dissipation by applying an advanced optimization tool embedded in MATLAB. Crank-Nicholson finite difference procedure is adopted to solve the partial differential equations of the consolidation equation in combined with the non-linear elastic visco-plastic model. As a result, the time dependent strain and excess pore water pressure dissipation in one dimensional compression are computed simultaneously. In this paper, a case study is presented to evaluate and validate the proposed method. © 2014 Taylor & Francis Group.
Li, JC, Li, Y, Askari, M & Ha, QP 1970, 'Future Intelligent Civil Structures: Challenges and Opportunities', Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 31st International Symposium on Automation and Robotics in Construction, International Association for Automation and Robotics in Construction (IAARC), Sydney, pp. 72-79.
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An intelligent civil structure offers ultimate protection to its structure, contents and occupants in terms of safety and functionality against undesired dynamic loadings and structural deficiency. In this paper, the concept of the future intelligent civil structure featuring self-adaptive, selfprognostic, self-sensing, self-powering and self-repairing abilities, is proposed. A decade research efforts from Centre for Built Infrastructure Research, University of Technology Sydney, towards the development and concept proof of such intelligent structure is reviewed.
Li, Y & Li, J 1970, 'Base isolator with variable stiffness and damping: design, experimental testing and modelling', Proceedings of the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 913-918.
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Vulnerability in base isolation system of civil structures originated from passive nature of the rubber material raises the urgency of developing smart base isolation system with adaptive and controllable properties, i.e. variable stiffness and damping. To address this issue, this paper presents comprehensive investigations on a novel adaptive base isolator, including design, experimental testing and dynamic modelling. Smart rubber with field-dependent modulus and damping property is incorporated into the laminated base isolator design. Experimental testing is conducted utilising an advanced shake table facility to examine its performance under cycling loading. Results show that the adaptive base isolator possesses a stiffness increase of more than 16 times and damping ratio between 10% and 27%. With such features, it can be developed into a smart base isolation system to protect civil structures against any type of earthquake. Results also show that this device has high nonlinear hysteresis, i.e. shear stiffening behaviour. A mechanical model is thus required to describe the complex behaviour of new adaptive base isolator. A new strain stiffening element is proposed for this purpose. Comparison between the model and the experimental data verifies the fidelity and effectiveness of the proposed model.
Li, Y, Li, J & ASME 1970, 'DEVELOPMENT AND MODELING OF A HIGHLY-ADJUSTABLE BASE ISOLATOR UTILIZING MAGNETORHEOLOGICAL ELASTOMER', PROCEEDINGS OF THE ASME CONFERENCE ON SMART MATERIALS, ADAPTIVE STRUCTURES, AND INTELLIGENT SYSTEMS - 2013, VOL 1, Conference on Smart Materials, Adaptive Structures and Intelligent Systems, ASME, Snowbird, Utah, USA, pp. 1-8.
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This paper presents a recent research breakthrough on the development of a novel adaptive seismic isolation system as the quest for seismic protection for civil structures, utilizing the field-dependent property of the magnetorheological elastomer (MRE). A highly-adjustable MRE base isolator was developed as the key element to form smart seismic isolation system. The novel isolator contains unique laminated structure of steel and MRE layers, which enable its large-scale civil engineering applications, and a solenoid to provide sufficient and uniform magnetic field for energizing the field-dependent property of MR elastomers. With the controllable shear modulus/damping of the MR elastomer, the developed adaptive base isolator possesses a controllable lateral stiffness while maintaining adequate vertical loading capacity. Experimental results show that the prototypical MRE base isolator provides amazing increase of lateral stiffness up to1630%. Such range of increase of the controllable stiffness of the base isolator makes it highly practical for developing new adaptive base isolation system utilizing either semi-active or smart passive controls. To facilitate the structural control development using the adaptive MRE base isolator, an analytical model was developed to stimulate its behaviors. Comparison between the analytical model and experimental data proves the effectiveness of such model in reproducing the behavior of MRE base isolator, including the observed strain stiffening effect. Copyright © 2013 by ASME.
Lloret-Cabot, M & Sheng, D 1970, 'Incremental stress-strain and suction-degree of saturation formulation in unsaturated soils', UNSATURATED SOILS: RESEARCH & APPLICATIONS, VOLS 1 AND 2, 6th International Conference on Unsaturated Soils (UNSAT), CRC Press, Sydney, AUSTRALIA, pp. 397-403.
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Mansor, NS, Shafri, HZM, Mansor, S & Paradhan, B 1970, 'The influence of urban development and social mobility on socioeconomic level: The application of GIS on urban ecosystems', IOP Conference Series: Earth and Environmental Science, IOP Publishing, pp. 012011-012011.
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Moshiri, F, Gardner, AP, Erkmen, E, Jarman, R & Khabbaz, H 1970, 'Enhancing Industry Exposure, Discovery-Based and CooperativeLearning in Mechanics of Solids', Australasian Association for Engineering Education Annual Conference 2014, Australasian Association for Engineering Education Annual Conference 2014, School of Engineering & Advanced Technology, Massey University, Turitea Campus, Palmerston North 4442, Wellington, NZ.
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BACKGROUND Mechanics of Solids is a second year undergraduate subject, undertaken by both Civil and Mechanical engineering students at the University of Technology, Sydney (UTS). Mechanics of Solids has been delivered for many years in a traditional format with lectures and problem solving tutorials. As part of a national Australian project “Enhancing Industry Exposure in Engineering Degrees”, UTS in partnership with other universities and industry partners in Australia has sought industry involvement to engage students with the real-world challenges of engineering practice. PURPOSEThe main objective of this project is to design, develop and implement learning modules in Mechanis of Solids that integrate industry exposure to provide context for the concepts included in this subject. DESIGNThe project consisted of six guest lectures by industry representatives on topics related to typical Mechanics of Solids subject matter and two seminars on using MDSolids software.Students completed a collaborative assignment aligned with one of the industry presentations. Their reports and presentations were assessed on assessment criteria which included contextual understanding, judgement, effective collaboration and creativity, and their perceptions were captured to evaluate the impact of industry engagement in this subject.RESULTSOne of the major benefits of this project was students’ better understanding of engineering practice. There were also positive effects on students’ motivation for learning engineering. CONCLUSIONS This paper reports the major findings, outcomes and challenges for implementing enhancing industry exposure approach in Mechanics of Solids subject at UTS. The main finding of this research concluded that this project is very valuable to both students as it promotes exposure to real-world engineering challenges. The students’ exposure to real and substantive challenges improves their contextual understanding, plus their judgement,...
Movassaghi, S, Abolhasan, M & Smith, D 1970, 'Cooperative scheduling with graph coloring for interference mitigation in wireless body area networks', 2014 IEEE Wireless Communications and Networking Conference (WCNC), 2014 IEEE Wireless Communications and Networking Conference (WCNC), IEEE, Turkey.
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Movassaghi, S, Abolhasan, M & Smith, D 1970, 'Smart Spectrum Allocation for Interference Mitigation in Wireless Body Area Networks', 2014 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE International Conference on Communications, IEEE, Australia, pp. 5688-5693.
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Movassaghi, S, Abolhasan, M, Smith, D & Jamalipour, A 1970, 'Joint Energy Harvesting and Internetwork Interference Mitigation amongst Coexisting Wireless Body Area Networks', Proceedings of the 9th International Conference on Body Area Networks, 9th International Conference on Body Area Networks, ICST, London, Great Britain.
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This paper investigates simultaneous transfer of information and energy for interference mitigation amongst multiple coexisting Wireless Body Area Networks (WBANs). We propose to utilize interference that falls into the network as a source of energy, which is mainly discarded in conventional interference mitigation schemes. More specifically, in each time slot, a single sensor node is scheduled to receive information whilst the remaining sensor nodes opportunistically harvest the ambient radio frequency energy. We develop a novel opportunistic scheduling scheme, which offers a significantly high network lifetime through a tradeoff between a sensor's spectral efficiency and average amount of energy harvested. Simulation results show that the proposed energy harvesting with smart channel allocation (E-SCA) scheme can achieve optimal spatial reuse and good energy harvesting. We also show that the proposed approach is robust to variations in channel conditions, density of sensor nodes in each WBAN and increase in number of coexisting WBANs.
Movassaghi, S, Abolhasan, M, Smith, D, Jamalipour, A & IEEE 1970, 'AIM: Adaptive Internetwork Interference Mitigation Amongst Co-existing Wireless Body Area Networks', 2014 IEEE Global Communications Conference (GLOBECOM 2014), IEEE Global Telecommunications Conference, IEEE, Austin, Texas, USA, pp. 2460-2465.
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Ngo, N, Indraratna, B & Rujikiatkamjorn, C 1970, 'A study of the behaviour of fresh and coal fouled ballast reinforced by geogrid using the discrete element method', Geomechanics from Micro to Macro - Proceedings of the TC105 ISSMGE International Symposium on Geomechanics from Micro to Macro, IS-Cambridge 2014, 3rd International Symposium on Geomechanics from Micro to Macro, CRC Press, Univ Cambridge, Cambridge, ENGLAND, pp. 559-563.
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Geogrids are widely used in ballasted rail tracks for reinforcement and stabilisation. During train operation, ballast becomes contaminated or fouled due to infiltration of fines from the surface, mud pumping from the subgrade, and degradation, which decreases the performance of the geogrids. This paper presents the results of a laboratory and numerical simulation to study the effect that coal fines have on the interface between ballast and geogrid. The stress-strain behaviour of fresh and fouled ballast reinforced by geogrid was investigated via a series of large scale direct shear tests in the laboratory and numerical simulations using the Discrete Element Method (DEM). The geogrid was modelled by bonding a large number of small spheres together to form the desired geometry and apertures. Irregular particle shapes were simulated in DEM by connecting many spheres together in appropriate sizes and positions. Fouled ballast was modelled by adding a predetermined amount of miniature spheres into the voids of the fresh ballast. The DEM results were then compared qualitatively with the laboratory data, and the effects of fines on the resulting shear stress-strain of ballast and the contact forces developed in the geogrids are discussed. © 2015 Taylor & Francis Group.
Nguyen, L, Fatahi, B & Khabbaz, H 1970, 'Modelling Behaviour of Cemented Clay Capturing Cementation Degradation', Ground Improvement and Geosynthetics, Geo-Shanghai 2014, American Society of Civil Engineers, Shanghai, China, pp. 168-177.
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This paper presents a constitutive model - referred to as the Cemented Cam Clay (CCC) model - to precisely simulate the cementation degradation of cement-treated clays. Various laboratory experiments show that the effect of cementation gradually diminishes as the confining pressure increases (particularly at high effective confining pressures) due to breakdown of cementation bonds. The main concepts and formulations of the CCC model, including elasto-plastic stress-strain relationships, are presented within the framework of the critical state concept and inspired by the Modified Cam Clay (MCC) model. The special characteristic of the proposed model includes a modified mean effective stress capturing cementation degradation. In addition, the failure envelope is formulated to describe the beneficial effect of cementation at low mean effective pressure range, while it merges with the Critical State Line of reconstituted cement-clay mixture as the confining pressure continues to increase. The performance of the proposed model is evaluated against triaxial test results from cement-treated Aberdeen soil. The model predictions provide good agreement with triaxial test results, particularly at high effective confining pressures. © ASCE 2014.
Nimbalkar, S & Indraratna, B 1970, 'Numerical and analytical modeling of particle degradation', Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014, International Conference of the International Association for Computer Methods and Advances in Geomechanics, CRC Press, Kyoto, Japan, pp. 261-266.
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Large cyclic loads are nowinevitable due to an increased demand for freight and public transport. The ballast layer subjected to these repeated traffic loads in a real track environment undergoes excessive deformation and degradation. Ballast degradation is influenced by various factors including the amplitude and number of load cycles, confining pressure, frequency, the angularity as well as fracture strength of individual grains. Given the complexities of the behaviour of the rail track, the current track analysis techniques are overly simplified. Considering this, an elasto-plastic constitutive model of a composite track is proposed. The largescale laboratory tests are simulated in a numerical model and the results are then analyzed to better understand the distribution of displacements and stresses inside the ballast layer. The advantages of the elasto-plastic finite element simulations when compared to conventional analytical methods used by practitioners that are primarily based on a linear elastic approach are demonstrated. © 2015 Taylor & Francis Group, London.
Oberst, S, Nava-Baro, E, Lai, JCS & Evans, TA 1970, 'An innovative signal processing technique for the extraction of ants' walking signals', INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control.
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Eusocial insects such as bees, ants and termites communicate multi-modally using chemical, visual, tactile and vibrational cues. While much work has been done on chemical and visual communications, the tactile and vibrational communication channel is somewhat neglected. Recent research indicates that structural vibrations caused by ants can be used to identify their activity level. However, these structural vibrations are caused by the response of the substrate excited by ants walking. The objective of this study is to determine the footprint of ants walking by separating the response of the substrate from the walking signal. The vibration of the substrate (in this case, a wooden veneer) caused by ants walking is measured by a laser vibrometer in an experimental setup isolated from environmental vibrations. By filtering the recorded vibration signal using a technique based on the dynamics in phase space followed by deconvolution from the response of the veneer using TIKHONOV regularisation, the ant's walking signal is extracted and its nature determined.
Parsa-Pajouh, A, Fatahi, B, Khabbaz, H & Vincent, P 1970, 'Evaluating Proposed Solutions for Equivalent Plane Strain Modeling of PVD Assisted Preloading', Advances in Transportation Geotechnics and Materials for Sustainable Infrastructure, Geo-Hubei 2014 International Conference on Sustainable Civil Infrastructure, American Society of Civil Engineers, China, pp. 9-16.
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In this study, a numerical code has been developed using free lossless audio codec (FLAC) 2-D to model the prefabricated vertical drain (PVD) assisted preloading process considering the smear zone, and evaluate the efficiency of the proposed equations for the conversion of permeability coefficient from axisymmetric state to plane-strain condition. A laboratory PVD assisted preloading test has been conducted employing a fully instrumented large Rowe cell to verify the developed numerical code. The results of the numerical plane-strain and axisymmetric simulations have been compared using four methods of permeability conversion from axisymmetric to plane-strain condition. © ASCE 2014.
Pathirage, U, Indraratna, B, McIntosh, G & Banasiak, L 1970, 'Modeling of mineral fouling in an alkaline permeable reactive barrier in Australia', COMPUTER METHODS AND RECENT ADVANCES IN GEOMECHANICS, Computer Methods and Recent Advances in Geomechanics, CRC Press, KYOTO, JAPAN, pp. 623-628.
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Rujikiatkamjorn, C & Indraratna, B 1970, 'Environmental Sustainability of Soft Soil Improvement via Vacuum and Surcharge Preloading', Geo-Congress 2014 Technical Papers, Geo-Congress 2014, American Society of Civil Engineers, pp. 3658-3665.
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Due to environmental concerns, sustainable ground improvement is considered a critical part of modern infrastructure development. Current policy on environmental sustainability often expects noise-free, chemical-free, and low carbon emission processes, while being economical. In this context, the application of prefabricated vertical drains (PVD) with vacuum preloading is regarded as one of the most sustainable ground improvement techniques. Compared with other ground improvement methods such as piling and chemical stabilization, this method will not only save a considerable cost in embankment construction, but will also improve the construction rate of coastal highways and rail tracks and their load-carrying capacity. The utilization of vacuum preloading will also minimize environmental impact by reducing greenhouse gas emissions and the need for mining natural surcharge fill. The FEM code ABAQUS with the equivalent approach is employed to study the performance of a full-scale test embankment constructed in Thailand. A comparison of the performance of the vacuum system with the standard surcharge fill is elucidated including its benefits and environmental impact. © 2014 American Society of Civil Engineers.
Sharma, N, Pal, U & Blumenstein, M 1970, 'A study on word-level multi-script identification from video frames', 2014 International Joint Conference on Neural Networks (IJCNN), 2014 International Joint Conference on Neural Networks (IJCNN), IEEE, Beijing, China, pp. 1827-1833.
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© 2014 IEEE. The presence of multiple scripts in multi-lingual document images makes Optical Character Recognition (OCR) of such documents a challenging task. Due to the unavailability of a single OCR system which can handle multiple scripts, script identification becomes an essential step for choosing the appropriate OCR. Although, there are various techniques available for script identification from handwritten and printed documents having simple backgrounds, however script identification from video frames has been seldom explored. Video frames are coloured and suffer from low resolution, blur, complex background and noise to mention a few, which makes the script identification process a challenging task. This paper presents a study of various combinations of features and classifiers to explore whether the traditional script identification techniques can be applied to video frames. A texture based feature namely, Local Binary Pattern (LBP), Gradient based features namely, Histogram of Oriented Gradient (HoG) and Gradient Local Auto-Correlation (GLAC) were used in the study. Combination of the features with SVMs and ANNs where used for classification. Three popular scripts, namely English, Bengali and Hindi were considered in the present study. Due to the inherent problems with the video, a super resolution technique was applied as a pre-processing step. Experiments show that the GLAC feature has performed better than the other features, and an accuracy of 94.25% was achieved when testing on 1271 words from three different scripts. The study also reveals that gradient features are more suitable for script identification than the texture features when using traditional script identification techniques on video frames.
Sheng, D, Zhao, G, Zhang, S & Niu, F 1970, 'Possible frost heave mechanisms in an unsaturated high-speed railway formation', UNSATURATED SOILS: RESEARCH & APPLICATIONS, VOLS 1 AND 2, 6th International Conference on Unsaturated Soils (UNSAT), CRC Press, Sydney, AUSTRALIA, pp. 3-14.
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Shivakumara, P, Sharma, N, Pal, U, Blumenstein, M & Tan, CL 1970, 'Gradient-Angular-Features for Word-wise Video Script Identification', 2014 22nd International Conference on Pattern Recognition, 2014 22nd International Conference on Pattern Recognition (ICPR), IEEE, Sweden, pp. 3098-3103.
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© 2014 IEEE. Script identification at the word level is challenging because of complex backgrounds and low resolution of video. The presence of graphics and scene text in video makes the problem more challenging. In this paper, we employ gradient angle segmentation on words from video text lines. This paper presents new Gradient-Angular-Features (GAF) for video script identification, namely, Arabic, Chinese, English, Japanese, Korean and Tamil. This work enables us to select an appropriate OCR when the frame has words of multi-scripts. We employ gradient directional features for segmenting words from video text lines. For each segmented word, we study the gradient information in effective ways to identify text candidates. The skeleton of the text candidates is analyzed to identify Potential Text Candidates (PTC) by filtering out unwanted text candidates. We propose novel GAF for the PTC to study the structure of the components in the form of cursiveness and softness. The histogram operation on the GAF is performed in different ways to obtain discriminative features. The method is evaluated on 760 words of six scripts having low contrast, complex background, different font sizes, etc. in terms of the classification rate and is compared with an existing method to show the effectiveness of the method. We achieve 88.2% average classification rate.
Siahaan, F, Indraratna, B & Rujikiatkamjorn, C 1970, 'Three dimensional modelling of the behaviour of stone columns using the discrete element method', Geomechanics from Micro to Macro, Vols I and II, 3rd International Symposium on Geomechanics from Micro to Macro, CRC Press, Univ Cambridge, Cambridge, ENGLAND, pp. 553-558.
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Suwanwiwat, H, Nguyen, V, Blumenstein, M & Pal, U 1970, 'Off-Line Handwritten Bilingual Name Recognition for Student Identification in an Automated Assessment System', 2014 14th International Conference on Frontiers in Handwriting Recognition, 2014 14th International Conference on Frontiers in Handwriting Recognition (ICFHR), IEEE, Greece, pp. 271-276.
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© 2014 IEEE. The Student name Identification System (SIS) proposed here was investigated for English and Thai languages combined. The proposed system recognises each name by using an approach for whole word recognition. In the proposed system, the Gaussian Grid Feature (GGF), and Modified Direction Feature (MDF), together with a proposed hybrid feature extraction technique called Water Reservoir, Loop and Gaussian Grid Feature (WRLGGF) were investigated on full word contour images of each name sample. Artificial neural networks and support vector machines were used as classifiers. An encouraging recognition accuracy of 99.25% was achieved employing the proposed technique compared to 98.59% for GGF, and 96.63% using MDF.
Suwanwiwat, H, Nguyen, V, Blumenstein, M & Pal, U 1970, 'Off-line handwritten Thai name recognition for student identification in an automated assessment system', 2014 International Joint Conference on Neural Networks (IJCNN), 2014 International Joint Conference on Neural Networks (IJCNN), IEEE, Beijing, PEOPLES R CHINA, pp. 2347-2353.
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Tennakoon, N, Indraratna, B & Nimbalkar, S 1970, 'Impact of Ballast Fouling on Rail Tracks', Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance, The Second International Conference on Railway Technology: Research, Development and Maintenance, Civil-Comp Press, Ajaccio, Corsica, France, pp. 1-11.
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© Civil-Comp Press, 2014. Ballast fouling is understood as major cause of track deterioration in many countries over the world. It decreases the drainage and load bearing capacity of the ballast layer. A series of large scale hydraulic conductivity tests were conducted with different proportions of fouling to access the drainage capacity of the track. A numerical analysis was conducted using SEEP/W to quantify the drainage capacity of ballast under different degrees of fouling. Subsequently, track drainage classification in relation to the degree of fouling, which is a very useful tool for practical engineers, is presented in this paper. The analysis showed that both the location and extent of fouling played an important role when assessing the overall drainage capacity of track. In order to establish the relationship between the extent of fouling and the associated strength-deformation properties, a series of large scale monotonic triaxial tests were carried out for different levels of fouling for three different confining pressures. Based on the laboratory findings, a novel empirical relationship between the peak deviator stress and VCI has been proposed to assist the practitioner in their preliminary track condition assessment. By considering drainage and strength aspects, a critical level of fouling to assist in track maintenance planning has been considered.
Trani, LD & Indraratna, B 1970, 'A Procedure to Assess Subballast Filtration under Cyclic Loading', Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance, The Second International Conference on Railway Technology: Research, Development and Maintenance, Civil-Comp Press.
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© Civil-Comp Press, 2014. Occurrences of inadequacies of subballast as a filtration layer of the ballasted rail tracks would become persistent if inappropriate criteria were still being used in the design. Traditionally, the subballast is considered mainly to act as a stress dissipation layer, more commonly known as a capping layer. Attention towards its function as a granular filter is proven by the fact that common design practice uses design criteria that are primarily based on steady seepage loading that is common in embankment dams. The seepage hydraulics through porous media is influenced by the cyclic mechanical loading generated by passing trains. Under the influence of cyclic train loading, subballast particles rearrange and attempt to attain a more stable configuration through the process of vertical compression, lateral spreading, and particle degradation. The deformability of the pore medium itself would then affect the filter condition due to the changes in porosity and its subsequent impact on hydraulic conductivity. This paper presents a procedure that combines a family of formulations and configuration charts that considers the effectiveness of the subballast as a granular filter being dependent on the reduction of its porosity and hydraulic conductivity over time.
Vinod, JS, Hyodo, M, Indraratna, B & Kajiyama, S 1970, 'Three-Dimensional Translucent Segregation Table (3D-TST) test for soil particle size and shape distribution', Geomechanics from Micro to Macro, Vols I and II, 3rd International Symposium on Geomechanics from Micro to Macro, CRC Press, Univ Cambridge, Cambridge, ENGLAND, pp. 1056-1061.
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Wang, Y, Lin, X, Zhang, Q & Wu, L 1970, 'Shifting Hypergraphs by Probabilistic Voting', Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), Springer International Publishing, pp. 234-246.
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In this paper, we develop a novel paradigm, namely hypergraph shift, to find robust graph modes by probabilistic voting strategy, which are semantically sound besides the self-cohesiveness requirement in forming graph modes. Unlike the existing techniques to seek graph modes by shifting vertices based on pair-wise edges (i.e, an edge with 2 ends), our paradigm is based on shifting high-order edges (hyperedges) to deliver graph modes. Specifically, we convert the problem of seeking graph modes as the problem of seeking maximizers of a novel objective function with the aim to generate good graph modes based on sifting edges in hypergraphs. As a result, the generated graph modes based on dense subhypergraphs may more accurately capture the object semantics besides the self-cohesiveness requirement. We also formally prove that our technique is always convergent. Extensive empirical studies on synthetic and real world data sets are conducted on clustering and graph matching. They demonstrate that our techniques significantly outperform the existing techniques. © 2014 Springer International Publishing.
Wijayaratna, KP, Labutis, LN & Waller, ST 1970, 'Dynamic User Optimal traffic assignment with recourse', Proceedings of the 19th International Conference of Hong Kong Society for Transportation Studies, HKSTS 2014 - Transportation and Infrastructure, pp. 525-532.
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Limitations of static network equilibrium models have led to numerous research efforts in predicting the temporal and spatial traffic conditions throughout road networks. Static models do not account for the dynamic nature of traffic. Accordingly, new approaches to depict these scenarios have been formulated, such as Dynamic User Optimal (DUO). This study extends DUO to DUO with recourse (DUOR) where a user can also alter their journey en-route dependent on the traffic conditions and the available information through ITS technology. This study proposes the modelling framework Dynamic User Optimal with Recourse using a Cell Transmission Model (DUOR-CTM). The model focuses on initially understanding whether a Dynamic User Optimal with Recourse (DUOR) solution arises and also determines the impact of information on the user optimal travel cost. The study presents the results of a sample network and highlights the need to account for information in a dynamic context.
Yang, C, Carter, J & Sheng, D 1970, 'On the compression behaviour of structured soils', COMPUTER METHODS AND RECENT ADVANCES IN GEOMECHANICS, Computer Methods and Recent Advances in Geomechanics, CRC Press, KYOTO, JAPAN, pp. 237-242.
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Yang, C, Sheng, D, Carter, JP, Pineda, J & Kelly, R 1970, 'From Compression Behavior to Plastic Anisotropy of Reconstituted Soft Soils', Soil Behavior and Geomechanics, Geo-Shanghai 2014, American Society of Civil Engineers, pp. 658-667.
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The plastic anisotropy of reconstituted soft soils is described from the compression behaviour observed during radial loading paths in stress space. A unique relationship is established between the orientation of the yield surface and the corresponding normal compression line, which indicates that a stabilized fabric is maintained under continuous loading along radial stress paths. The equilibrium orientation angle of the plastic potential surface is obtained explicitly. A new rotational hardening law is proposed by considering the dependence of the evolution of anisotropic fabric with the current stress condition and plastic strain. An elastoplastic constitutive model for anisotropic soil is formulated within the framework of Critical State Soil Mechanics. Validation with experimental data and predictions from other models demonstrate the feasibility of the basic concept and the capacity of the proposed new model. © 2014 American Society of Civil Engineers.
Yu, Y, Dackermann, U, Li, J & Yan, N 1970, 'Guided-wave-based damage detection of timber poles using a hierarchical data fusion algorithm', Proceedings fo the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 1203-1208.
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This paper presents a hierarchical data fusion algorithm based on the combination of wavelettransform (WT), back propagation neural network (BPNN) and Dempster-Shafer (D-S) evidencetheory for the multi-sensor guided-wave-based (GW-based) damage detection of in-situ timber utilitypoles. In the data-level fusion, noise elimination is performed on the original wave data to obtainsingle-mode signals using WT technology. Statistical information is extracted from the single-modelsignals as major characteristic parameters. In the feature-level fusion, for each sensor in the testingsystem, two sub-networks corresponding to different types of GW signals are constructed based onBPNN and characteristic parameters are sent to the networks for initial state recognition. In thedecision-level fusion, the D-S evidence theory method is adopted to combine the initial results fromdifferent sensors for final decision making. The overall algorithm employs a hierarchical configuration,in which the results from the former level are regarded as input to the next level. To validate theproposed method, it was tested on GW signals from in-situ timber poles. The obtained damagedetection results clearly demonstrate the effectiveness and accuracy of the proposed algorithm.
Yu, Y, Li, Y & Li, J 1970, 'A New Hysteretic Model for Magnetorheological Elastomer Base Isolator and Parameter Identification Based on Modified Artificial Fish Swarm Algorithm', Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC), 31st International Symposium on Automation and Robotics in Construction, International Association for Automation and Robotics in Construction (IAARC), Sydney, pp. 176-183.
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Magnetorheological elastomer (MRE) base isolator is a new semi-active control device that has recently acquired more attention. This paper proposes a new model for MRE base isolator to portray the nonlinear hysteresis between generated force and the displacement. In this model, a hyperbolic expression is proposed to compare with the classical Bouc-Wen model, which includes internal dynamics represented by a nonlinear differential equation. For the identification of model parameters, a modified artificial fish swarm algorithm is adopted using the experimental force-displacement/velocity data under different testing conditions. In this algorithm, a self-adaptive method for adjusting the algorithm parameters is introduced to improve the result accuracy. Besides, the behaviours in the algorithm are simplified to descend the algorithmic complexity. Parameter identification results are included to demonstrate the accuracy of the model and the effectiveness of the identification algorithm.
Yu, Y, Li, Y & Li, J 1970, 'A Novel Strain Stiffening Model for Magnetorheological Elastomer Base Isolator and Parameter Estimation Using Improved Particle Swarm Optimization', Proceedings of the 6th edition of the World Conference of the International Association for Structural Control and Monitoring (IACSM), Sixth World Conference on Structural Control and Monitoring (6WCSCM), International Center for Numerical Methods in Engineering (CIMNE), Barcelona, Spain.
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In order to fully utilize the advantages of magnetorheological elastomer (MRE) base isolator for seismic protection of civil structures, a high fidelity model should be established to characterize its nonlinear hysteresis for its implementation in structural control. In this paper, a novel strain stiffening model is developed to capture this unique characteristic. In this model, a strain stiffening component, which described the unique viscos-elastic behavior of the device, is incorporated with a Voigt element, which portrays the solid-material behavior. The new model, as an attractive feature, maintains a relationship between the isolator parameters and physical force-displacement nonlinear phenomenon and decreases the complexity in other existing models. In addition to the proposed model, an improved optimization algorithm based on particle swarm optimization (IPSO) is designed to identify the model parameters by utilizing experimental force-displacement-velocity data acquired from various loading conditions. In this new algorithm, the mutation operation in genetic algorithm is utilized for helping the model solution avoiding the local optimum. The superiority of the proposed model and parameter solving algorithm is validated by comparing them with the classical Bouc-Wen model and other optimization algorithms through the error analysis, respectively. The comparison results show that the proposed model can exactly predict the force-displacement and force-velocity responses at both small and large displacements, and has a smaller root-mean-square (MSE) error than the Bouc-Wen model. Compared with other optimization algorithm, the IPSO not only has a faster convergence rate, but also obtains the satisfactory parameters identification results.
Yu, Y, Li, Y & Li, J 1970, 'Parameter Identification Of An Improved Dahl Model For Magnetorheological Elastomer Base Isolator Based On Enhanced Genetic Algorithm', Proceedings of the 23rd Australasian Conference on the Mechanics of Structures and Materials, Australasian Conference on the Mechanics of Structures and Materials, Southern Cross University, Byron Bay, Australia, pp. 931-936.
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In view of the problems of high nonlinearity and multiple parameters in existing models of magnetorheological elastomer (MRE) base isolator, this paper proposes an improved Dahl model and an enhanced genetic algorithm (GA) for model parameter identification. In this model, the Dahl hysteresis operator is employed to depict the Coulomb force to avoid the estimation of many parameters and this model can perfectly capture the hysteretic behavior of the MRE base isolator at both small and large displacements. To improve the searching efficiency of identification process, adaptive crossover and mutation operators are introduced into the GA to avoid the algorithm falling into the local optimum, achieving faster convergence rate for optimal solutions. Furthermore, an appropriate stopping criterion is designed to reduce the calculation cost. Testing data from a practical MRE base isolator are utilized to validate the proposed algorithm with satisfactory parameter identification results.
Yusof, NM & Pradhan, B 1970, 'Landslide susceptibility mapping along PLUS expressways in Malaysia using probabilistic based model in GIS', IOP Conference Series: Earth and Environmental Science, IOP Publishing, pp. 012031-012031.
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Zhang, B, Wang, Y, Wang, Y & Chen, F 1970, 'Stable Learning in Coding Space for Multi-class Decoding and Its Extension for Multi-class Hypothesis Transfer Learning', 2014 IEEE Conference on Computer Vision and Pattern Recognition, 2014 IEEE Conference on Computer Vision and Pattern Recognition (CVPR), IEEE, Columbus, OH, pp. 1075-1081.
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Zhang, X, Krabbenhoft, K & Sheng, DC 1970, 'Particle Finite Element Simulation of Granular Media', Applied Mechanics and Materials, Trans Tech Publications, Ltd., pp. 410-415.
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Despite their ubiquity, the simulation of granular materials poses a continuing challenge in computational mechanics, as these materials can behave like solid, liquid and gas. In this paper, a recently developed version of the Particle Finite Element Method is applied for analyzing the behaviour of granular media under very large deformations. Both quasi-static and dynamic problems are considered. It is shown that this continuum approach is applicable to general large deformation problems of granular materials, including liquid-like flows.
Zhang, Z, Oberst, S & Lai, JCS 1970, 'A stochastic approach to predicting brake squeal propensity', 21st International Congress on Sound and Vibration 2014, ICSV 2014, 21st International Congress on Sound and Vibration 2014, ICSV 2014, pp. 629-636.
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Brake squeal as a significant noise, vibration and harshness (NVH) issue to the automotive industry is triggered by friction-induced self-excited vibration. Validating theoretical predictions using analytical or numerical models against experiments is difficult because the test results are often not repeatable even under apparently similar operating conditions. The poor repeatability of brake squeal could be attributed to the nonlinearity of the dynamics involved and the uncertainties associated with material properties, boundary conditions (such as contact pressure, temperature, stiffness, exact area of contact) and operating conditions. In this paper, a stochastic approach to predicting brake squeal propensity is examined using an analytical model of a popular 4-DOF friction oscillator with constant friction coefficient. Instability of this model is first estimated using the conventional linear complex eigenvalue analysis (CEA) and compared with calculations of positive friction work. The sensitivity of this deterministic model to variations of parameters such as spring stiffness and damping coefficient is studied. To account for uncertainties in the exact values of parameters, the analytical model is studied using polynomial chaos expansions with beta distribution on a set of Jacobi polynomials. Probabilities for instabilities based on positive friction work are determined and the implications for estimating squeal propensity in a full brake system are discussed.
Zhang, Z, Oberst, S & Lai, JCS 1970, 'Instability prediction of brake squeal by nonlinear stability analysis', INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014 - 43rd International Congress on Noise Control Engineering: Improving the World Through Noise Control.
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Prediction of brake squeal as unwanted high frequency noise above 1 kHz remains a challenging problem despite substantial research efforts in the past two decades. Brake squeal, triggered by friction-induced self-excited vibration, can be caused by many different and interacting mechanisms with nonlinear origins in material properties and boundary conditions. Although brake squeal is essentially a nonlinear phenomenon, the standard industrial practice for prediction of brake squeal relies on the linear complex eigenvalue analysis which may under-predict or over-predict the number of unstable vibration modes. Brake squeal can be considered in nonlinear dynamics terms to be caused by a friction-induced self-excitation driven into instability and oscillating in a limit cycle through super-critical Andronov-Hopf bifurcations. In this paper, a nonlinear stability analysis that may be applied to a full brake system is examined using an unforced 4-DOF friction oscillator with cubic nonlinearity. The local bifurcation behaviour of this model is studied using the normal form theory and the nonlinear stability boundary is evaluated. Differences between results of linear and nonlinear analyses are discussed and the limitations of the linear analysis are highlighted. The energy provided by friction and consumed by damping is calculated by multiple scales method to provide a physical explanation for instability generation.
Zhou, A & Sheng, D 1970, 'Modeling hydro-mechanical behaviors for unsaturated soils with different initial densities via stress-saturation framework with subloading concept', Computer Methods and Recent Advances in Geomechanics, Computer Methods and Recent Advances in Geomechanics, CRC Press, KYOTO, JAPAN, pp. 1385-1390.
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Zhou, AN & Sheng, D 1970, 'Modeling density effect on hydro-mechanical behavior of unsaturated soils', Unsaturated Soils: Research and Applications - Proceedings of the 6th International Conference on Unsaturated Soils, UNSAT 2014, 6th International Conference on Unsaturated Soils (UNSAT), CRC PRESS-TAYLOR & FRANCIS GROUP, Sydney, AUSTRALIA, pp. 503-509.
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This paper presents an advanced constitutive model for unsaturated soil based on subloading surface plasticity. The proposed model is capable of modelling typical hydro-mechanical behaviour of soils compacted to different initial densities. Bishop's effective stress and the effective degree of saturation are selected as two fundamental constitutive variables in the proposed constitutive model. A sub-loading surface and a unified hardening parameter are introduced into the stress-saturation modelling framework to interpret the effects of initial density on hydro-mechanical behaviour of compacted soils. The proposed advanced unsaturated soil model is then validated against a number of experimental results reported in the literature. © 2014 Taylor & Francis Group, London.
