- Department of Civil Engineering, Faculty of Engineering Building, University of Malaya, 50603 Kuala Lumpur, MALAYSIA
- I was a professor of civil engineering specialising in transportation engineering and planning until my retirement re... moreI was a professor of civil engineering specialising in transportation engineering and planning until my retirement recently. Currently actively involved as president of Transportation Science Society of Malaysia (TSSM) and vice-president of the Clean Air Forum Society of Malaysia (MyCAS)edit
Research Interests:
Research Interests:
The ageing of the bitumen during storage, mixing, transport and laying on the road, as well as in service life, are the most important problems presented by the use of bitumen in pavements. This paper investigates the possibility of using... more
The ageing of the bitumen during storage, mixing, transport and laying on the road, as well as in service life, are the most important problems presented by the use of bitumen in pavements. This paper investigates the possibility of using waste cooking oil (WCO), which is a waste material that pollutes landfills and rivers, as an alternative natural rejuvenating agent for aged bitumen to a condition that resembles the original bitumen. With this target, the physical and chemical properties of the original bitumen, aged bitumen and rejuvenated bitumen were measured and compared by the bitumen binder tests - softening point, penetration, Brookfield viscosity, dynamic shear rheometer and Fourier transform infrared spectroscopy. In addition, the behaviour of the WCO rejuvenated bitumen is investigated and compared with virgin bitumen after using the rolling thin film oven ageing process. In general, the results showed that using 3-4% of WCO the aged bitumen group 40/50 was rejuvenated to a condition that closely resembled the physical, rheological properties of the original bitumen (80/100), however, there was a difference in the tendency to ageing between the WCO rejuvenated bitumen and the virgin bitumen during mixing, transport and laying on the road. © 2012 Elsevier B.V.
http://www.sciencedirect.com/science/article/pii/S0304389412006632
http://www.sciencedirect.com/science/article/pii/S0304389412006632
Research Interests: Recycling, Rheology, FTIR spectroscopy, Waste Management, Water Pollution, and 36 moreOils, Mixing, Fatty acids, Cooking, Oil, Infrared spectroscopy, Flow measurement, Chemical Analysis, Article, Asphalt Pavements, Pavement, Temperature measurement, HYDROCARBONS, Vegetable oil, Fourier transform infrared spectroscopy, Bitumen, Rejuvenation, Landfill, Unclassified Drug, Physico chemical Properties, Utilization of cementitious industrial waste products (slag, fly ash, silica fume) and natural pozzolans, Physical and Chemical Properties, Bituminous Materials, Dynamic Shear Rheometer, Rheological Property, Rolling Thin Film Ovens, Aged Bitumen, Bitumen Binder, Softening Points, Rejuvenating Agent, Rheological Characteristics, Binders\, Roads and Streets, Cooking Fat, Domestic Waste, and Physicochemical Property
A new clustering algorithm that uses a weighted Mahalanobis distance as a distance metric to perform partitional clustering is proposed. The covariance matrices of the generated clusters are used to determine cluster similarity and... more
A new clustering algorithm that uses a weighted Mahalanobis distance as a distance metric to perform partitional clustering is proposed. The covariance matrices of the generated clusters are used to determine cluster similarity and closeness so that clusters which are similar in shape and close in Mahalanobis distance can be merged together serving the ultimate goal of automatically determining the optimal number of classes present in the data. Properties of the new algorithm are presented by examining the clustering quality for codebooks designed with the proposed method and another common method that uses Euclidean distance. The new algorithm provides better results than the competing method on a variety of data sets. Application of this algorithm to the problem of detecting suspicious regions in a mammogram is discussed.
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=710194&tag=1
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=710194&tag=1
Research Interests:
Wave-induced seabed instability, either momentary liquefaction or shear failure, is an important topic in ocean and coastal engineering. Many factors, such as seabed properties and wave parameters, affect the seabed instability. A... more
Wave-induced seabed instability, either momentary liquefaction or shear failure, is an important topic in ocean and coastal engineering. Many factors, such as seabed properties and wave parameters, affect the seabed instability. A non-dimensional parameter is proposed in this paper to evaluate the occurrence of momentary liquefaction. This parameter includes the properties of the soil and the wave. The determination of the wave-induced liquefaction depth is also suggested based on this non-dimensional parameter. As an example, a two-dimensional seabed with finite thickness is numerically treated with the EFGM meshless method developed early for wave-induced seabed responses. Parametric study is carried out to investigate the effect of wavelength, compressibility of pore fluid, permeability and stiffness of porous media, and variable stiffness with depth on the seabed response with three criteria for liquefaction. It is found that this non-dimensional parameter is a good index for identifying the momentary liquefaction qualitatively, and the criterion of liquefaction with seepage force can be used to predict the deepest liquefaction depth. © 2006 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0029801806000886
http://www.sciencedirect.com/science/article/pii/S0029801806000886
Research Interests: Ocean Engineering, Coastal Engineering, Numerical Modeling, Discontinuous Galerkin Methods, Liquefaction, and 17 moreElement-Free Galerkin Methods, Porous Materials, Seabed Mapping, Water Waves, Soil Dynamics-Liquefaction, Wave hydrodynamics, Wave forces on marine structures, Breakwaters, Submarine pipelines, Extreme waves and winds, Wave, Ocean thermal and tidal energy, Soil Stiffness, Wing in Ground Effect, Airfoil, Parametric Study, Galerkin Method, Wind-generated Wave Loading, Pore Pressure, Shear Failure, Mechanical Permeability, Pore Water Pressure, Momentary Liquefaction, Wave-induced Seabed, and Wave-seafloor Interaction
The last decade has witnessed an increased number of vehicles and increased vehicle speed on roads such that the frequency and severity of run-off roadway accidents has increased dramatically. Evaluation of guardrail system performance as... more
The last decade has witnessed an increased number of vehicles and increased vehicle speed on roads such that the frequency and severity of run-off roadway accidents has increased dramatically. Evaluation of guardrail system performance as an element of providing a safe environment for vehicles and to reduce occupant injuries is deemed to be vital issue. Hence, this paper is going to assess deflection and vehicle trajectory of current guardrail systems. For this purpose, the results of full-scale crash tests for different types of guardrail system are collected from previous crash tests available in the literature. The results showed that for Test 3-11 (according to NCHRP Report 350) with similar post spacing (1905 mm), the trend of vehicle exit speed declined while guardrail maximum permanent deflection increased. In addition, among all system types, guardrail with curb and Thrie-beam guardrail systems were subjected to the lowest amount of deflection although Thrie-beam guardrail was subjected to higher average values for both vehicle exit speed and exit angle. Further, weak-post guardrail system showed to have the highest maximum dynamic and permanent deformation compared to other systems whereas it caused the lowest exit angle to the vehicles. © 2013 Taylor and Francis.
http://www.tandfonline.com/doi/abs/10.1080/13588265.2013.815020#.UrvmF_uA_5M
http://www.tandfonline.com/doi/abs/10.1080/13588265.2013.815020#.UrvmF_uA_5M
Research Interests: Road safety, Crash tests, Safety Performance, Vehicles, Crashworthiness, and 12 moreLongitudinal Barriers, Permanent Deformations, Vehicle Trajectory, Vehicle Trajectories, Accident Prevention, Automobile Testing, Crash Test, Full-scale Crash Tests, Number of Vehicles, Guard Rails, Motor Transportation, and Accidents\
Road safety barriers protect vehicles from roadside hazards by redirecting errant vehicles in a safe manner as well as providing high levels of safety during and after impact. This paper focused on transition safety barrier systems which... more
Road safety barriers protect vehicles from roadside hazards by redirecting errant vehicles in a safe manner as well as providing high levels of safety during and after impact. This paper focused on transition safety barrier systems which were located at the point of attachment between a bridge and roadside barriers. The aim of this study was to provide an overview of the behavior of transition systems located at upstream bridge rail with different designs and performance levels. Design factors such as occupant risk and vehicle trajectory for different systems were collected and compared. To achieve this aim a comprehensive database was developed using previous studies. The comparison showed that Test 3-21, which is conducted by impacting a pickup truck with speed of 100 km/h and angle of 25 to transition system, was the most severe test. Occupant impact velocity and ridedown acceleration for heavy vehicles were lower than the amounts for passenger cars and pickup trucks, and in most cases higher occupant lateral impact ridedown acceleration was observed on vehicles subjected to higher levels of damage. The best transition system was selected to give optimum performance which reduced occupant risk factors using the similar crashes in accordance with Test 3-21. © 2013 Elsevier Ltd. All rights reserved.
http://www.ncbi.nlm.nih.gov/pubmed/23820073
http://www.sciencedirect.com/science/article/pii/S0001457513002285
http://www.ncbi.nlm.nih.gov/pubmed/23820073
http://www.sciencedirect.com/science/article/pii/S0001457513002285
Research Interests: Road safety, Accidents, Crash tests, Vehicles, Trucks, and 12 morePassenger cars, Longitudinal Barriers, Occupant Risk, Roadsides, Vehicle Trajectory, Occupant Impact Velocity, Optimum Performance, Road Safety Barriers, Safety Barrier Systems, Vehicle Trajectories, Accident Prevention, and Automobile Testing
Most highly motorized countries in the world have implemented different speed limits for light weight and heavy weight vehicles. The heavy vehicle speed limit is usually chosen to be lower than that of passenger cars due to the difficulty... more
Most highly motorized countries in the world have implemented different speed limits for light weight and heavy weight vehicles. The heavy vehicle speed limit is usually chosen to be lower than that of passenger cars due to the difficulty for the drivers to safely maneuver the heavy vehicle at high speed and greater impact during a crash. However, in many cases, the speed limit for heavy vehicle is set by only considering the vehicle size or category, mostly due to simplicity in enforcement. In this study, traffic and vehicular data for all vehicle types were collected using a weigh-in-motion system installed at Federal Route 54 in Malaysia. The first finding from the data showed that the weight variation for each vehicle category is considerable. Therefore, the effect of gross vehicle weight (GVW) and category of heavy vehicle on free flow speed and their interaction were analyzed using statistical techniques. Empirical analysis results showed that statistically for each type of heavy vehicle, there was a significant relationship between free flow speed of a heavy vehicle and GVW. Specifically, the results suggest that the mean and variance of free flow speed decrease with an increase GVW by the amount unrelated to size and shape for all GVW range. Then, based on the 85th percentile principle, the study proposed a new concept for setting the speed limit for heavy vehicle by incorporating GVW where a different speed limit is imposed to the heavy vehicle, not only based on vehicle classification, but also according to its GVW. © 2010 Elsevier Ltd All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0001457510003908
http://www.sciencedirect.com/science/article/pii/S0001457510003908
Research Interests: Automobiles, Weigh in motion system, Statistical Techniques in Spatial Analysis, Speed, Variable Speed Limit (VSL), and 16 moreVehicle Classification, Synthesis of gold nanoparticles by size and shapes, Plug In Hybrid Electric Vehicles, Empirical Analysis, Different Speed, Light Weight, Differential Speed Limit, Free Flow Speed, Heavy Vehicle, Vehicle Weight, Gross Vehicle Weight, Heavy Weight Vehicles, Vehicle Size, Vehicle Types, Weigh-in-motion Systems, and Weigh-in-motion (WIM)
Video and image processing have been used for traffic supervision, analysis and monitoring of traffic condition in many cities and urban areas. The system described in this paper aims to approach the precise method to obtain the traffic... more
Video and image processing have been used for traffic supervision, analysis and monitoring of traffic condition in many cities and urban areas. The system described in this paper aims to approach the precise method to obtain the traffic flow, time headway and traffic volume through a sequence of images captured with a stationary video camera. The method consists of three algorithms. First, background modeling and update, second, a boosting method to enhance the foreground image and reduce the noise and at last determining best match of region of interest (ROI) to extract information to conclude if there is a vehicle in the detection zone or not. Based on this structure, the traffic quantity measurement (TQM) algorithm is represented to compute the important parameters in traffic sense that will be useful for traffic condition observation and management as well. In this research, the traffic quantities such as time headway and traffic flow have been measured. The experimental result shows this method obtains traffic flow and time headway with around 91% of accuracy in shadow free area and can be used in real time condition. © 2011 Academic Journals.
http://www.scopus.com/inward/record.url?eid=2-s2.0-79956209438&partnerID=40&md5=b751f66003b7bd3756590a5b8ae2d192
http://www.scopus.com/inward/record.url?eid=2-s2.0-79956209438&partnerID=40&md5=b751f66003b7bd3756590a5b8ae2d192
Research Interests:
Pavement structures commonly fall into two main categories, namely, flexible and rigid pavements. Such structures just as other structures are susceptible to different types of distresses. In order to minimize the deterioration of... more
Pavement structures commonly fall into two main categories, namely, flexible and rigid pavements. Such structures just as other structures are susceptible to different types of distresses. In order to minimize the deterioration of pavements, geosynthetic reinforcement is one of the techniques adopted to improve their performance. As a result, employment of different geosynthetics to pavement structures is reported by various researchers. This paper aims to present and discuss the findings from some of the studies on utilizing geosynthetics in flexible pavements. Furthermore, three most common usages of geosynthetics, so called, fluid barrier, strain absorbing, and reinforcement agent in pavement structures are investigated in this paper. © 2011 Academic Journals.
http://www.scopus.com/inward/record.url?eid=2-s2.0-79959852731&partnerID=40&md5=991f41e3c0e8f6c61f199ba6cffe2f3d
http://www.scopus.com/inward/record.url?eid=2-s2.0-79959852731&partnerID=40&md5=991f41e3c0e8f6c61f199ba6cffe2f3d
Research Interests:
Nowadays, large amounts of waste materials are being produced in the world. One of the waste materials is plastic bottle. Generating disposable plastic bottles is becoming a major problem in many countries. Using waste plastic as a... more
Nowadays, large amounts of waste materials are being produced in the world. One of the waste materials is plastic bottle. Generating disposable plastic bottles is becoming a major problem in many countries. Using waste plastic as a secondary material in construction projects would be a solution to overcome the crisis of producing large amount of waste plastics in one hand and improving the structure's characteristics such as resistance against cracking on the other hand. This study aimed to investigate the effects of adding plastic bottles in road pavement. Marshall properties as well as specific gravity of asphalt mixture containing different percentages of plastic bottles were evaluated. Besides, Optimum Asphalt Content (OAC) was calculated for each percentages of plastic bottles used in the mix. The stiffness and fatigue characteristics of mixture were assessed at OAC value. Results showed that the stability and flow values of asphalt mixture increased by adding waste crushed plastic bottle into the asphalt mixture. Further, it was shown that the bulk specific gravity and stiffness of mixtures increased by adding lower amount of plastic bottles; however, adding higher amounts of plastic resulted in lower specific gravity and mix stiffness. In addition, it was concluded that the mixtures containing waste plastic bottles have lower OAC values compared to the conventional mixture, and this may reduce the amount of asphalt binder can be used in road construction projects. Besides, the mixtures containing waste plastic showed significantly greater fatigue resistance than the conventional mixture. © School of Engineering, Taylor's University.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CCoQFjAA&url=http%3A%2F%2Fdlisv03.media.osaka-cu.ac.jp%2Finfolib%2Fuser_contents%2Fkiyo%2FDB00010953.pdf&ei=_9O7UrvoLYj_rAes2oDIAw&usg=AFQjCNGu1y_NTWI-jif_LFDnZj1bv4kDfA&sig2=9ohwJLXq6mPyP8l8AvU3xg&bvm=bv.58187178,d.bmk
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CCoQFjAA&url=http%3A%2F%2Fdlisv03.media.osaka-cu.ac.jp%2Finfolib%2Fuser_contents%2Fkiyo%2FDB00010953.pdf&ei=_9O7UrvoLYj_rAes2oDIAw&usg=AFQjCNGu1y_NTWI-jif_LFDnZj1bv4kDfA&sig2=9ohwJLXq6mPyP8l8AvU3xg&bvm=bv.58187178,d.bmk
Research Interests:
Fatigue and rutting are very well known to be the two popular distresses that occur in road pavement. These are mainly due to the increase in the number of vehicles particularly those with high axle loads, due to the environmental... more
Fatigue and rutting are very well known to be the two popular distresses that occur in road pavement. These are mainly due to the increase in the number of vehicles particularly those with high axle loads, due to the environmental conditions and also due to construction and design errors. As a consequence the service life of asphalt pavement is affected and will be decreased. Various researches reported that using additives such as different types of polymer and fiber in asphalt concrete (AC) could be a solution to postpone deterioration of AC pavement. This paper aims to highlight previous research works conducted on the effects of using different types of additives and aggregate gradation on fatigue and rutting resistance of AC mixtures. It was observed that fatigue and rutting resistance of AC mixture could be enhanced considerably by utilization of different types of additives such as fibers that can increase the amount of strain energy absorbed during fatigue and fracture process of the mix in the resulting composite. Also, fibers and polymers provide three-dimensional networking effect in asphalt concrete and stabilise the binder on surface of aggregate particles and prevent from any movement at higher temperature. © 2011 Academic Journals.
http://umexpert.um.edu.my/file/publication/00003145_67419.pdf
http://umexpert.um.edu.my/file/publication/00003145_67419.pdf
Research Interests:
There is substantial evidence on the advantages of using crumb rubber in enhancing conventional bitumen properties, gaining environmental protection and boosting industrial-economical benefits. Thus, the use of this ingenious additive in... more
There is substantial evidence on the advantages of using crumb rubber in enhancing conventional bitumen properties, gaining environmental protection and boosting industrial-economical benefits. Thus, the use of this ingenious additive in bitumen modification through sustainable technology is highly advocated.The main objective of this research is to investigate the effects of different blending conditions (of time and temperature) and various crumb rubber contents on the properties of bitumen binders. Testing was conducted using the Dynamic shear rheometer (DSR) test and softening point test. The results showed that differing crumb rubber contents and blending temperature have significant effects on modified binder properties whereas the blending time showed an insignificant effect. Higher blending temperature and crumb rubber content were found to influence the interaction of bitumen-rubber blends and also increased the swelling rate of rubber particles, resulting in an increase in complex shear modulus (G*), storage modulus (G'), loss modulus (G") and softening point as well as a decrease in phase angle (δ). Thus, the modified bitumen became less susceptible to deformation after stress removals. The study also presented a considerable relationship between rheological parameters (G*, G', G' and δ) and softening point in terms of predicting physical-mechanical properties regardless of blending conditions. Thus, in terms of elasticity for the softening point data, the storage modulus and phase angle were found to be good indicators of binder elasticity. When softening point is made available, a prediction about binder ability to recover its original shape after stress removals can be done.
http://www.scielo.br/scielo.php?pid=S1516-14392013000100015&script=sci_arttext&tlng=es
http://www.scielo.br/scielo.php?pid=S1516-14392013000100015&script=sci_arttext&tlng=es
Research Interests: Rheology, Customer Relationship Management (CRM), Elasticity, Physical and Mechanical Properties of Polymers, The Role of Information and Communication Technology (ICT) in Achieving Sustainable Socio-Economic Development (e-Commerce, e-Business & e-Government), and 11 moreRecycled Tire Rubber, Proteinaceous Binders in Artworks, Blending, Elastic Moduli, Recycling Waste Bituminous Materials, Dynamic Shear Rheometer, Low-temperature Susceptibility, Modified Bitumen, Blending Conditions, Complex Shear Modulus, and Rheological Parameter
Today, rapid economic and industrial growth generates increasing amounts of waste materials such as waste tyre rubber. Attempts to inspire a green technology which is more environmentally friendly that can produce economic value are a... more
Today, rapid economic and industrial growth generates increasing amounts of waste materials such as waste tyre rubber. Attempts to inspire a green technology which is more environmentally friendly that can produce economic value are a major consideration in the utilization of waste materials. The aim of this study is to evaluate the effect of waste tyre rubber (crumb rubber modifier (CRM)), in stone mastic asphalt (SMA 20) performance. The virgin bitumen (80/100) penetration grade was used, modified with crumb rubber at four different modification levels, namely, 6%, 12%, 16%, and 20% by weight of the bitumen. The testing undertaken on the asphalt mix comprises the indirect tensile (dynamic stiffness), dynamic creep, and wheel tracking tests. By the experimentation, the appropriate amount of CRM was found to be 16% by weight of bitumen. The results show that the addition of CRM into the mixture has an obvious significant effect on the performance properties of SMA which could improve the mixture's resistance against permanent deformation. Further, higher correlation coefficient was obtained between the rut depth and permanent strain as compared to resilient modulus; thus dynamic creep test might be a more reliable test in evaluating the rut resistance of asphalt mixture. © 2013 Nuha Salim Mashaan and Mohamed Rehan Karim.
http://www.hindawi.com/journals/tswj/2013/981637/abs/
http://www.hindawi.com/journals/tswj/2013/981637/abs/
To prevent pavement distresses there are various solutions such as adopting new mix designs or utilisation of asphalt additives. The primary aim of this study was to investigate the effect of adding crumb tyre rubber as an additive to SMA... more
To prevent pavement distresses there are various solutions such as adopting new mix designs or utilisation of asphalt additives. The primary aim of this study was to investigate the effect of adding crumb tyre rubber as an additive to SMA mixture performance properties. This study investigated the essential aspects of modified asphalt mixtures in order to better understand the influence of CRM modifiers on volumetric, mechanical, and stiffness properties of SMA mixture. In this study, virgin bitumen 80/100 penetration grade was used, modified with crumb rubber (CRM) at five different modification levels, namely, 6%, 12%, 16%, and 20%, respectively, by weight of the bitumen. The appropriate amount of the added CRM was found to be 12% by weight of bitumen. This percentage results in the maximum level of stability. The resilient modulus (Mr) of modified SMA samples including different percentages of CRM was obviously higher in comparison with that of unmodified samples. © 2013 Nuha Salim Mashaan et al.
http://www.hindawi.com/journals/amse/2013/304676/abs/
http://www.hindawi.com/journals/amse/2013/304676/abs/
Research Interests:
Today, virgin polymer modified asphalt mixes are comparatively more expensive for road pavement. One way to reduce the expense of such construction and to make it more convenient is the application of inexpensive polymer, such as waste... more
Today, virgin polymer modified asphalt mixes are comparatively more expensive for road pavement. One way to reduce the expense of such construction and to make it more convenient is the application of inexpensive polymer, such as waste polymer. The primary aim of this study was to investigate the effect of adding waste tyre rubber (crumb rubber modifier (CRM)) on the stiffness and fatigue properties of stone mastic asphalt (SMA) mixtures. Various percentages of waste CRM with size of 0.60 mm were added to SMA mixtures. Indirect tensile stiffness modulus test was conducted at temperatures of 5, 25, and 40°C. Indirect tensile fatigue test was conducted at three different stress levels (2000, 2500, and 3000 N). The results show that the stiffness modulus of reinforced SMA samples containing various contents of CRM is significantly high in comparison with that of nonreinforced samples, and the stiffness modulus of reinforced samples is in fact less severely affected by the increased temperature compared to the nonreinforced samples. Further, the results show that CRM reinforced SMA mixtures exhibit significantly higher fatigue lives compared to the nonreinforced mixtures help in and promotion of sustainable technology by recycling of waste materials in much economical and environmental-friendly manner. © 2013 Nuha Salim Mashaan et al.
http://www.hindawi.com/journals/amse/2013/319259/abs/
http://www.hindawi.com/journals/amse/2013/319259/abs/
Research Interests: Polymers, Sustainable Technology, Stiffness, Reinforcement, Bending Deformation and Fatigue Properties of Precision-Casting TiNi Shape Memory Alloy Brain Spatula, and 11 moreRubber, Mixtures, Fatigue Testing, Fatigue of Materials, Stone Mastic Asphalts, Mastic Asphalt, Crumb Rubber Modifiers, Indirect Tensile Fatigue, Environmental-friendly, Increased Temperature, and Recycling of Wastes
Roadways are considered one of the most important elements of infrastructure and they play an essential role in our daily lives. In road pavement construction, the use of crumb rubber in the modification of bitumen binder is considered as... more
Roadways are considered one of the most important elements of infrastructure and they play an essential role in our daily lives. In road pavement construction, the use of crumb rubber in the modification of bitumen binder is considered as a smart solution for sustainable development by reusing waste materials. It is believed that crumb rubber modifier (CRM) could be one of the alternative polymer materials in improving bitumen binder performance properties of hot mix asphalt. This study aims to present and discuss the findings from some of the studies, on the use of crumb rubber in asphalt pavement. © 2012 Academic Journals.
http://www.scopus.com/inward/record.url?eid=2-s2.0-84856144477&partnerID=40&md5=23d979a9800f89c408ee1e20958966fa
http://www.scopus.com/inward/record.url?eid=2-s2.0-84856144477&partnerID=40&md5=23d979a9800f89c408ee1e20958966fa
Research Interests:
The increase use of crumb rubber in flexible pavements requires the better understanding of its effect on physical and rheological properties of rubberised bitumen binders. The performance properties of rubberised bitumen binder are... more
The increase use of crumb rubber in flexible pavements requires the better understanding of its effect on physical and rheological properties of rubberised bitumen binders. The performance properties of rubberised bitumen binder are influenced by the blending conditions and crumb rubber content. The main objective of this research is to investigate the effect of various crumb rubber content on the physical, rheological properties and rutting resistance of rubberised bitumen. Laboratory tests were conducted to evaluate such related properties of bitumen binder with different rubber contents. The tests undertaken comprise the ductility test, elastic recovery test, penetration test and dynamic shear rheometer (DSR) test. The results showed that the addition of crumb rubber has an effect on the physical properties of rubberised bitumen binders, by increasing its elastic recovery and decreasing its penetration and ductility. The rubberised bitumen binder with higher crumb rubber content has an obvious effect on the rheological properties (increase in complex shear modulus G, storage modulus G', loss modulus G'' and decrease in phase angle δ). The results indicated that the rubber content has the potential to resist rutting deformation that occurs in road pavement as result of increased traffic loading. © 2011 Academic Journals.
www.researchgate.net/publication/228987935_Effect_of_crumb_rubber_concentration_on_the_physical_and_rheological_properties_of_rubberised_bitumen_binders/file/79e4150fe00b90cdef.pdf
www.researchgate.net/publication/228987935_Effect_of_crumb_rubber_concentration_on_the_physical_and_rheological_properties_of_rubberised_bitumen_binders/file/79e4150fe00b90cdef.pdf
Research Interests:
The increasing use of crumb rubber modifier in flexible pavements justifies the necessity for a better understanding of its physical and rheological properties as well as its elasticity behaviour. Basically the performance and properties... more
The increasing use of crumb rubber modifier in flexible pavements justifies the necessity for a better understanding of its physical and rheological properties as well as its elasticity behaviour. Basically the performance and properties of rubberised asphalt binder are influenced by the blending conditions and crumb rubber content. In this study, the laboratory investigation was conducted on crumb rubber modified asphalt binder properties as a function of two blending times (30 minutes and 60 minutes) and five crumb rubber contents (4, 8, 12, 16 and 20% by weight of asphalt binder) at mixing temperature of 180°C. Statistical analysis using two-way ANOVA was conducted on the results to evaluate the significance of rubber contents and blending times. The rubberised asphalt binder was evaluated in terms of binder elasticity and rutting resistance at high temperature. The results indicate that the crumb rubber content had a significant effect on G*/ sin (δ) at 76°C. The higher crumb rubber content appears to dramatically increase the elastic recovery and ductility. Statistical analysis showed significant effect of crumb rubber content in influencing the ductility, elastic recovery and G*/ sin (δ) values. Whereas the blending time do not appears to significantly affect the ductility, elastic recovery and rutting factor (G*/ sin (δ)) of the CRM asphalt binder. The asphalt binder with higher crumb rubber content and longer blending time of 60 minutes exhibited a higher value of elastic recovery. This indicates that crumb rubber modified asphalt binder has better resistance to rutting as compared to conventional asphalt binder. © 2011 Academic Journals.
www.researchgate.net/publication/234411075_Effect_of_blending_time_and_crumb_rubber_content_on_properties_of_crumb_rubber_modified_asphalt_binder/file/9fcfd50fe03ace8b73.pdf
www.researchgate.net/publication/234411075_Effect_of_blending_time_and_crumb_rubber_content_on_properties_of_crumb_rubber_modified_asphalt_binder/file/9fcfd50fe03ace8b73.pdf
Research Interests:
This paper presents the finite element (FE) analysis of the consolidation of the foundation of an embankment constructed over soft clay deposit which shows significant time dependent behaviour and was improved with prefabricated vertical... more
This paper presents the finite element (FE) analysis of the consolidation of the foundation of an embankment constructed over soft clay deposit which shows significant time dependent behaviour and was improved with prefabricated vertical drains. To assess the capability of a simple elastic viscoplastic (EVP) model to predict the long term performance of a geotechnical structure constructed on soft soils, a well documented (Leneghans) embankment was analyzed to predict its long term behaviour characteristics. Two fully coupled two dimensional (2D) plane strain FE analyses have been carried out. In one of these, the foundation of the embankment was modelled with a relatively simpler time dependent EVP model and in the other one, for comparison purposes, the foundation soil was modelled with elasto-plastic Modified Cam-clay (MCC) model. Details of the analyses and the results are discussed in comparison with the field performance. Predictions from the creep (EVP) model were found to be better than those from Elasto-plastic (MCC) analysis. However, the creep analysis requires an additional parameter and additional computational time and resources. © 2011 Taylor & Francis.
http://www.tandfonline.com/doi/abs/10.1080/17486025.2011.578667#.Uruek_uA_5M
http://www.tandfonline.com/doi/abs/10.1080/17486025.2011.578667#.Uruek_uA_5M
Research Interests:
Asphalt modification/reinforcement has received considerable attention as viable solutions to enhance flexible pavement performance. This is mainly prompted by the unsatisfactory performance of traditional road materials exposed to... more
Asphalt modification/reinforcement has received considerable attention as viable solutions to enhance flexible pavement performance. This is mainly prompted by the unsatisfactory performance of traditional road materials exposed to dramatic increases and changes in traffic patterns. This paper presents the characteristics and properties of glass fiber reinforced Stone Mastic Asphalt. Laboratory tests were conducted to evaluate such related properties of asphalt mixture with different fiber contents. The tests undertaken comprise the Marshall test, indirect tensile test, creep test and fatigue test using repeated load indirect tensile test. The results showed that the addition of fiber does affect the properties of bituminous mixes, by decreasing its stability and increasing the voids in the mix. Stiffness properties of reinforced SMA mix were enhanced by about 12% as compared to control mix. Mixes with more than 0.2% fiber content exhibited lower resistance to permanent deformation. The results indicated that the fiber has the potential to resist structural distress that occur in road pavement as result of increased traffic loading, thus improving fatigue life by increasing the resistance to cracking and permanent deformation especially at higher stress level. © 2010 Academic Journals.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&ved=0CEYQFjAD&url=http%3A%2F%2Facademicjournals.org%2Fjournal%2FIJPS%2Farticle-full-text-pdf%2FF1F5C1F32034&ei=SJy7UvKKKcnSrQexg4DYCQ&usg=AFQjCNEB3s_PDXDOIHmoxsdB6cwq4zabnQ&sig2=Jufa0LCjQtFLdZKkfZuWeQ&bvm=bv.58187178,d.bmk
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&ved=0CEYQFjAD&url=http%3A%2F%2Facademicjournals.org%2Fjournal%2FIJPS%2Farticle-full-text-pdf%2FF1F5C1F32034&ei=SJy7UvKKKcnSrQexg4DYCQ&usg=AFQjCNEB3s_PDXDOIHmoxsdB6cwq4zabnQ&sig2=Jufa0LCjQtFLdZKkfZuWeQ&bvm=bv.58187178,d.bmk
Research Interests:
A new methodology for computational plasticity of nonassociated frictional materials is presented. The new approach is inspired by the micromechanical origins of friction and results in a set of governing equations similar to those of... more
A new methodology for computational plasticity of nonassociated frictional materials is presented. The new approach is inspired by the micromechanical origins of friction and results in a set of governing equations similar to those of standard associated plasticity. As such, procedures previously developed for associated plasticity are applicable with minor modification. This is illustrated by adaptation of the standard implicit scheme. Moreover, the governing equations can be cast in terms of a variational principle, which after discretization is solved by means of a newly developed second-order cone programming algorithm. The effects of nonassociativity are discussed with reference to localization of deformations and illustrated by means of a comprehensive set of examples. © 2012 John Wiley & Sons, Ltd.
http://onlinelibrary.wiley.com/doi/10.1002/nme.3358/full
http://onlinelibrary.wiley.com/doi/10.1002/nme.3358/full
Research Interests: Soil, Plasticity, Mathematical Programming, Soils, Friction, and 11 moreRICCATI TECHNIQUES AND VARIATIONAL PRINCIPLES IN OSCILLATION THEORY FOR LINEAR SYSTEMS, Governing Equations, Nonassociated Flow, Discretizations, Frictional Materials, Implicit Schemes, Localization of Deformation, Micro-mechanical, Nonassociativity, Second-order Cone Programming, and Variational Principles
A new methodology for computational plasticity of nonassociated frictional materials is presented. The new approach is inspired by the micromechanical origins of friction and results in a set of governing equations similar to those of... more
A new methodology for computational plasticity of nonassociated frictional materials is presented. The new approach is inspired by the micromechanical origins of friction and results in a set of governing equations similar to those of standard associated plasticity. As such, procedures previously developed for associated plasticity are applicable with minor modification. This is illustrated by adaptation of the standard implicit scheme. Moreover, the governing equations can be cast in terms of a variational principle, which after discretization is solved by means of a newly developed second-order cone programming algorithm. The effects of nonassociativity are discussed with reference to localization of deformations and illustrated by means of a comprehensive set of examples. © 2012 John Wiley & Sons, Ltd.
http://onlinelibrary.wiley.com/doi/10.1002/nme.3358/full
http://onlinelibrary.wiley.com/doi/10.1002/nme.3358/full
Research Interests: Soil, Plasticity, Mathematical Programming, Soils, Friction, and 11 moreRICCATI TECHNIQUES AND VARIATIONAL PRINCIPLES IN OSCILLATION THEORY FOR LINEAR SYSTEMS, Governing Equations, Nonassociated Flow, Discretizations, Frictional Materials, Implicit Schemes, Localization of Deformation, Micro-mechanical, Nonassociativity, Second-order Cone Programming, and Variational Principles
In a code division multiple access (CDMA) spread spectrum system, each user is assigned a unique scrambling code. If these codes are not mutually orthogonal, the resulting multiple access interference (MAI) causes frame error rates to be... more
In a code division multiple access (CDMA) spread spectrum system, each user is assigned a unique scrambling code. If these codes are not mutually orthogonal, the resulting multiple access interference (MAI) causes frame error rates to be unacceptably high. A number of multi-user detection algorithms have been suggested by various authors. Optimal receivers based upon maximum likelihood sequence decoding are quite complex, their complexity increasing exponentially with the number of users in the system. Sub-optimal receivers such as linear detectors or adaptive cancellers are not as complex, but the error rates increase with the number of users. In this paper, we suggest a new multi-user detection procedure using an antenna array at the receiver. First, we provide an upper bound on the minimum mean-squared error due to MAI, and show how the frame error rate increases with the number of users. The transmitted symbols are estimated by inverting the transfer function of the channel, multiplying it with the outputs of matched filters, and then passing the result through a maximum likelihood decoder. Our analysis indicates that if the channel impulse response is known with sufficient accuracy, this procedure leads to an optimal design. In those cases where the impulse response is only approximately known, we estimate the transmitted symbols and compute the resulting baseband SNR. If this SNR is above a threshold, the baseband signal is acceptable and ready for maximum likelihood sequence decoding. Otherwise, the impulse response is adjusted in small steps until the SNR is above that threshold. © 2007 IEEE.
ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4454747
ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4454747
Research Interests: Antennas, Antenna arrays, Channel Estimation, Learning Systems, Mean square error, and 39 moreImpulse response, Maximum Likelihood, Multiuser Detection, Error Analysis, Maximum Likelihood Estimation, Decoding, Signal - to - noise ratio, Multiple-access Interference, Singular-spectrum Analysis, Military operations, Codes (Symbols), Adaptive Cancellers, Base Band (BB) Signals, Baseband (BB), Channel Impulse Response (CIR), Code Division Multiple Access (CDMA2000), Error Rate (ER), Frame Error Rate (FER), Frame Error Rates (FER), Linear Detectors, Matched Filters (MFs), Maximum Likelihood (ML) Decoder, Minimum Mean-squared Error (MMSE), Multi-user Detection (MUD), Multiple-access-interference (MAI), Optimal Designs, Optimal Receivers, Spread Spectrum (SS) System, Spread-spectrum Signals, Transmitted Symbols, Upper Bounds, Acoustic Intensity, Antenna Accessories, Block Codes, Code Division Multiple Access, Codes (Standards), Military Communications, Radio Interference, and Transfer Functions
The phenomenon of excess pore water pressure increase or stagnation and continuing large ground deformation in soft sensitive clay following the completion of construction of embankment is simulated for a case study at Saint Alban,... more
The phenomenon of excess pore water pressure increase or stagnation and continuing large ground deformation in soft sensitive clay following the completion of construction of embankment is simulated for a case study at Saint Alban, Quebec, Canada. The present model employs an updated Lagrangian finite element framework and is combined with an automatic time increment selection scheme. The simulation based on an elasto-viscoplastic constitutive model considers soil-structure degradation effect. It is shown that without consideration for the microstructural degradation effect, it is not possible to reproduce the field responses of soft sensitive clay even during the construction of the embankment. When the soil-structure degradation effect is considered, the present model can offer reasonably accurate prediction for the consolidation behavior of soft sensitive clay, including the so-called anomalous pore water pressure generation and continuing large deformation even after the end of construction, which has been posing numerous uncertainties on the long-term performance of earth structures. © 2013 John Wiley & Sons, Ltd.
onlinelibrary.wiley.com/doi/10.1002/nag.2165/full
onlinelibrary.wiley.com/doi/10.1002/nag.2165/full
Research Interests: Microstructure, Viscoplasticity, Finite element method, Soil-Structure Interaction, Performance Assessment, and 27 moreCanada, Deformation, Elastoplasticity, Soils, Consolidation, Soft Soil, Soil Structure, Numerical Model, Femslash, Clay Soil, Pore Pressure, Flow Beneath Embankments, Pressure Distribution, Embankment, Pore-water Pressures, Porewater, Time Dependent Behavior, Elasto-viscoplasticity, Time Increments, Anomalous Pore Water Pressure, Long-term Consolidation, Soft Sensitive Clay, Soil Structural Degradation, Sensitive Clays, Structural Degradation, Constitutive Equation, and Quebec [Canada]
An automatic time increment selection scheme for numerical analysis of long-term response of geomaterials is presented. The scheme is simple, rational and stable. Governed by a simple empirical expression, it can adaptively adjust the... more
An automatic time increment selection scheme for numerical analysis of long-term response of geomaterials is presented. The scheme is simple, rational and stable. Governed by a simple empirical expression, it can adaptively adjust the time increments depending on the strain rate-dependent temporal history of the material response. The proposed expression requires only a few parameters whose selection is a trivial task since they have a small effect on accuracy but have a significant effect on computational efficiency. This generalization has been made possible because of the enforcement of certain predefined control criteria to avoid extreme conditions. If any of the control criteria is satisfied, the computation is restarted by going a few time steps back to ensure the smoothness of the computed responses and time increments are again continuously adjusted through the governing equation provided. Performance of the automatic time increment selection scheme is investigated through finite element analyses of the long-term consolidation response of clay under different geotechnical profiles and loading conditions. Both elastic and elasto-viscoplastic constitutive relations are considered, including the consideration of the destructuration effects of geomaterials. Numerical results show that the performance of the automatic time increment selection scheme is reasonably excellent. While offering reasonable accuracy of the numerical solution, it can ensure temporal stability at optimal computational efficiency. In addition to the Euler implicit method, the automatic time increment selection scheme also performs well even when the explicit fourth-order Runge-Kutta method is employed for the integration of time derivatives. © 2010 Taylor & Francis.
http://www.tandfonline.com/doi/abs/10.1080/17486020903576226#.UruWKPuA_5M
http://www.tandfonline.com/doi/abs/10.1080/17486020903576226#.UruWKPuA_5M
Research Interests:
A two-dimensional numerical procedure is presented to analyse the transient response of saturated porous elastic soil layer under cyclic loading. The procedure is based on the element-free Galerkin method and incorporated into the... more
A two-dimensional numerical procedure is presented to analyse the transient response of saturated porous elastic soil layer under cyclic loading. The procedure is based on the element-free Galerkin method and incorporated into the periodic conditions (temporal and spatial periodicity). Its shape function is constructed by moving least-square approximants, essential boundary conditions are implemented through Lagrange multipliers and the periodic conditions are implemented through a revised variational formulation. Time domain is discretized through the Crank-Nicolson scheme. Analytical solutions are developed to assess the effectiveness and accuracy of the current procedure in one and two dimensions. For only temporal periodic problems, a one-dimensional transient problem of finite thickness soil layer is analysed for sinusoidal surface loading. For both temporal and spatial periodic problems, a typical two-dimensional wave-induced transient problem with the seabed of finite thickness is analysed. Finally, a moving boundary problem is analysed. It is found that the current procedure is simple, efficient and accurate in predicting the response of soil layer under cyclic loading. © 2002 Elsevier Science Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0020768302004973
http://www.sciencedirect.com/science/article/pii/S0020768302004973
Research Interests: Soil, Water, Porous Materials, Elasticity, Mathematical Analysis, and 14 moreSoils, Cyclic Loading, Loading, Lagrange Multiplier, Boundary Value Problems, Porous Medium, Pore Pressure, Cyclic Loads, Element-free Galerkin Method, Moving Least-square Approximants, Periodic Boundary, Pore Water Pressure, Galerkin Methods, and Porous Elastic Soils
The consolidation of the soft foundation soil of a geogrid-reinforced embankment, improved with prefabricated vertical drains (PVDs), is modelled in this paper using two-dimensional (2D) plane strain coupled finite element (FE) analysis... more
The consolidation of the soft foundation soil of a geogrid-reinforced embankment, improved with prefabricated vertical drains (PVDs), is modelled in this paper using two-dimensional (2D) plane strain coupled finite element (FE) analysis to predict long-term multiple behaviour characteristics (e.g., settlement, lateral displacement, excess pore-water pressure response, geosynthetic strain) of the embankment. Two sets of analyses were carried out with the foundation soil being modelled using relatively simple elastic-viscoplastic (EVP) models. A nonlinear creep function was used in association with them. The input material parameters were determined from extensive laboratory testing or were taken from reliable sources except for the horizontal permeability, which was systematically back-estimated using oedometer test data and the first year of field settlement data. The results from both analyses were compared with the long-term (up to 6 years) field-monitoring data and were found to be in good agreement with the field measurements.
http://www.nrcresearchpress.com/doi/abs/10.1139/t10-104#.UruSufuA_5M
http://www.nrcresearchpress.com/doi/abs/10.1139/t10-104#.UruSufuA_5M
Research Interests: Finite Element Methods, Viscoplasticity, Prediction, Soil Mechanics, Finite Elements, and 42 moreHydraulic Structures, Performance Assessment, Creep, Soft soils, Permeability, Geosynthetics, Soil Reinforcement, Consolidation, Soft Soil, Field Measurements, Drainage, First Year, Long Term Performance, Plane Strain, Two Dimensional, Soft Clay, Coupled Circuits, Monitoring System, Flow Beneath Embankments, Foundation Soils, Geologic Models, Embankment, Elastic Viscoplastic, Soft Clays, Material Parameter, Pore-water Pressures, Porewater, Time Dependent Behavior, Plane Strain Analysis, Time-dependency, Laboratory Testing, Lateral Displacements, Non-linear Creep, Oedometer Tests, Plane Strains, Pre-fabricated Vertical Drains, Settlement Data, Soft Foundation, Two-dimensional Finite Element Analysis, Geosynthetic Materials, Data Set, and Field Method
The problem of extracting effective diffusivities of cement pastes on the basis of X-ray microtomography images is considered. A general computational homogenization framework is developed and applied to a variety of cement pastes whose... more
The problem of extracting effective diffusivities of cement pastes on the basis of X-ray microtomography images is considered. A general computational homogenization framework is developed and applied to a variety of cement pastes whose microstructure has been digitized to a resolution of 1 mu m. At this resolution, important submicron features are not resolved. Consequently, we propose a methodology whereby the pore space is ascribed a diffusivity less than the free diffusivity. For this purpose, a simple rule that incorporates microtomography data is proposed and shown to yield satisfactory results.
http://onlinelibrary.wiley.com/doi/10.1002/9781118557723.ch19/summary
http://onlinelibrary.wiley.com/doi/10.1002/9781118557723.ch19/summary
Research Interests: Finite Elements, Reinforced Concrete Structures, Diffusion, 3PL Third Party logistics relationships size, - Micromechanics and homogenization methods; analysis of composite materials and structures., and 7 moreMicrotomography, XMT, Cement Paste, Representative Volume Element, 2-dimensional Composites, Transport-properties, and Migration Test
Two new renormalization schemes for conductivity upscaling in heterogeneous media are presented. The schemes follow previous ones by performing the renormalization over square cells of size 2 d with d being the dimensionality. Contrasting... more
Two new renormalization schemes for conductivity upscaling in heterogeneous media are presented. The schemes follow previous ones by performing the renormalization over square cells of size 2 d with d being the dimensionality. Contrasting with previous schemes, the two-dimensional scheme makes use of the exact 2 × 2 block-conductivity. On the basis of the structure of the exact two-dimensional block-conductivity, an analogous three-dimensional scheme is proposed. The new schemes are tested on a number of benchmark problems and are shown to be significantly more accurate than existing schemes. © 2010 Springer Science+Business Media B.V.
http://link.springer.com/article/10.1007/s11242-010-9585-9
http://link.springer.com/article/10.1007/s11242-010-9585-9
Research Interests:
Vehicle overloading has been identified as one of the major contributors to road pavement damage in Malaysia. In this study, the weigh-in-motion (WIM) system has been used to function as a vehicle weight sorting tool to complement the... more
Vehicle overloading has been identified as one of the major contributors to road pavement damage in Malaysia. In this study, the weigh-in-motion (WIM) system has been used to function as a vehicle weight sorting tool to complement the exsiting static weigh bridge enforcement station. Data collected from the developed system is used to explore the effectiveness of using WIM system in terms of generating more accurate data for enforcement purposes and at the same time improving safety and reducing the number of vehicle weight violations on the roads. This study specifically focus on the effect of vehicle by-pass and static weigh station enforcement capability on the overall effectiveness of vehicle weight enforcement system in a developing country. Results from this study suggest that the WIM system will significantly enhance the effectiveness and efficiency of the current vehicle weight enforcement, thus generating substantial revenue that would greatly off-set the current road maintenance budget that comes from tax payers money. If there is substantial reduction in overloaded vehicles, the public will still gain through reduction in road maintenance budget, less accident risks involving heavy trucks, and lesser greenhouse gases (GHGs) emissions. © 2013 International Association of Traffic and Safety Sciences.
http://www.sciencedirect.com/science/article/pii/S0386111213000174
http://www.sciencedirect.com/science/article/pii/S0386111213000174
Research Interests:
This paper presents modelling of the consolidation of foundation soil under a wide embankment constructed over soft soil. An elastic-viscoplastic (EVP) constitutive model is used to represent the foundation soil for the coupled finite... more
This paper presents modelling of the consolidation of foundation soil under a wide embankment constructed over soft soil. An elastic-viscoplastic (EVP) constitutive model is used to represent the foundation soil for the coupled finite element analysis (FEA). A unit-cell analysis is carried out to capture the maximum settlement and the development of excess pore-water pressure with time below the centreline of the embankment for a long period (9 years). A new function for capturing the varying nature of the creep or secondary compression coefficient is proposed and used in association with the EVP model. The input material parameters for this study were determined from extensive laboratory experiments except for the equivalent horizontal permeability, which was systematically estimated by using vertical permeability data obtained from one-dimensional consolidation tests and by back-analysing the first 12 months of field settlement data. Comparisons are made among the predictions obtained adopting an elastoplastic modified Cam clay model and the EVP model with constant and varying creep coefficients for the foundation soil and the corresponding field data. The predictions with the EVP model are found to be better than those with the elastoplastic model and the use of a varying creep coefficient for the EVP model seems to further improve its predicting ability.
http://www.ingentaconnect.com/content/nrc/cgj/2010/00000047/00000002/art00009
www.nrcresearchpress.com/doi/abs/10.1139/T09-087
http://www.ingentaconnect.com/content/nrc/cgj/2010/00000047/00000002/art00009
www.nrcresearchpress.com/doi/abs/10.1139/T09-087
Research Interests: Finite Element Methods, Plasticity, Viscoplasticity, Forecasting, Removal Of Heavy Metals In Contaminated Soils, and 42 moreHydraulic Structures, Finite Element Analysis, Creep, Soft soils, Permeability, Foundation, Data acquisition, Viscosity, Ground Water Analysis, Elastoplasticity, Embankment Dams, Three-dimensional computer modelling of Roman fort and settlement sites and reconstruction from geophysical data sets, Soft Soil, Elasto-plastic, Parameterization, Laboratory Experiments, Long Term Performance, Canals, Soft Clay, Consolidation of Structures In Situ, Flow Beneath Embankments, Field Data, Foundation Soils, Geologic Models, Vertical Permeabilities, Elastic Viscoplastic, Time Dependency, Elasto-plastic Models, Material Parameter, Modified Cam-clay Model, One Dimensional Consolidation, Pore-water Pressures, Secondary Compression, Unit Cells, Capillarity\, Constitutive Models, Elastic Property, Laboratory Method, One-dimensional Modeling, Porewater, Pressure Effect, and Time Dependent Behavior
Geo-synthetic reinforcements are often used to enhance the stability of geotechnical structures such as embankments. These geosynthetic polymers often show significant creep deformational behaviour. In the short-term performance of a... more
Geo-synthetic reinforcements are often used to enhance the stability of geotechnical structures such as embankments. These geosynthetic polymers often show significant creep deformational behaviour. In the short-term performance of a geotechnical structure, it may not play a significant role. However, while dealing with the long term behaviour, it is necessary to investigate its effect. In this paper two plane strain fully coupled finite element analysis have been conducted; one with and the other without taking into account of the creep behaviour of geosynthetics. A well documented field case of Leneghans embankment (Geogrid improved wide embankment constructed near Sydney, Australia in 1990s) have been used for this purpose. It is evident from the analyses that though the geosynthetic reinforcements may play a vital role in the performance/stability of an embankment in the early days (during and after construction), its contribution may become insignificant with time and the creep of geo-synthetic may not play a significant role in the long term stability. © 2012 American Society of Civil Engineers.
http://cedb.asce.org/cgi/WWWdisplay.cgi?289267
http://cedb.asce.org/cgi/WWWdisplay.cgi?289267
This paper models the consolidation of the foundation soil of a wide geogrid reinforced embankment close to its centre-line. An elastic viscoplastic model has been used for the analysis. A creep function that takes into account of the... more
This paper models the consolidation of the foundation soil of a wide geogrid reinforced embankment close to its centre-line. An elastic viscoplastic model has been used for the analysis. A creep function that takes into account of the non-linear nature of creep has also been incorporated in this model. The predicted results are compared with the field measurement data and with the analysis results obtained using two other models (i.e. Kutter and Sathialingham, 1992 and modified Cam-Clay). © 2009 IOS Press.
http://www.scopus.com/inward/record.url?eid=2-s2.0-84865189953&partnerID=40&md5=646bebabd73375f165d2c1e540ad1039
http://www.scopus.com/inward/record.url?eid=2-s2.0-84865189953&partnerID=40&md5=646bebabd73375f165d2c1e540ad1039
Research Interests: Geotechnical Engineering, Soil Mechanics, Creep, Consolidation, Embankments, and 15 moreSettlement Analysis, Paper Models, Soft Clay, Performance Dimension Fields design, Foundation Soils, Geologic Models, Embankment, Time Dependent Behaviour, Creep Functions, Elastic Viscoplastic, Field Measurement Data, Geogrids, Reinforced Embankments, Soft Clays, and Time-dependent Behaviour
Video and image processing has been used for traffic surveillance, analysis and monitoring of traffic conditions in many cities and urban areas. This paper aims to present another approach to estimate the vehicles velocity. In this study,... more
Video and image processing has been used for traffic surveillance, analysis and monitoring of traffic conditions in many cities and urban areas. This paper aims to present another approach to estimate the vehicles velocity. In this study, the captured traffic movies are collected with a stationary camera which is mounted on a freeway. The camera was calibrated based on geometrical equations that were supported directly by using references. Camera calibration for exact measurements may be possible while accurate speed estimation can still be quite difficult to achieve. The designed system has the ability to be extended to another related traffic application. The average error of the detected vehicle speed was ± 7 km/h and the experiment was operated at different resolutions and different video sequences. © 2010 Academic Journals.
http://umexpert.um.edu.my/file/publication/00003145_64925.pdf
http://umexpert.um.edu.my/file/publication/00003145_64925.pdf
Research Interests:
Drawing upon some earlier work on coherent states of the Poincare' group in 1-space and 1-time dimensions, we use these states to define a relativistic windowed Fourier transform, as relativistic extension of the usual windowed Fourier... more
Drawing upon some earlier work on coherent states of the Poincare' group in 1-space and 1-time dimensions, we use these states to define a relativistic windowed Fourier transform, as relativistic extension of the usual windowed Fourier transform. We discretize the resulting transform and obtain conditions under which the discretized transform can be used to reconstruct arbitrary square integrable functions. We present some numerical and graphical exercises to illustrate the theory, as well as to compare the relativistic windowed Fourier transform with the orthodox windowed Fourier transform.
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=00845572
http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=00845572
Research Interests:
Two trial piles were installed at the berm section of an embankment in the later stage of its construction and one of them was fitted with an oversized casing to isolate its top 3. m from the action of surrounding soil. Lateral bending... more
Two trial piles were installed at the berm section of an embankment in the later stage of its construction and one of them was fitted with an oversized casing to isolate its top 3. m from the action of surrounding soil. Lateral bending behaviour these two piles subjected to passive sub soil movements were very different from each other because of the casing and is modelled in this paper using a three dimensional analysis. The effect of relative stiffness of the piles on their lateral bending behaviour is investigated. The effect of interface joint slip on the pile's behaviour is also investigated in a later section of this paper. © 2013 Elsevier Ltd.
http://www.sciencedirect.com/science/article/pii/S0266352X13000591
http://www.sciencedirect.com/science/article/pii/S0266352X13000591
Research Interests: Soil-Structure Interaction, Movement, Piles, Stiffness, Soils, and 15 moreThree dimensional modeling and simulation, Embankment Dams, Bending, Embankments, 3D Analysis, Embankment Construction, Lateral Bending, Relative Stiffness, Soil Movements, Surrounding Soils, Three-dimensional Analysis, Construction Method, Subsoil, Structural Response, and Pile Response
In present mobile radio systems, conventional FM techniques are used to transmit speech in its analog form. A number of digital schemes have been proposed in the past as an alternative. To overcome the effects of Rayleigh fades that... more
In present mobile radio systems, conventional FM techniques are used to transmit speech in its analog form. A number of digital schemes have been proposed in the past as an alternative. To overcome the effects of Rayleigh fades that appear in the received speech as noise bursts in the form of `pops' and `clicks', we propose, in this paper, packetizing speech and encoding the packets in an error-detecting code before transmitting them. If the receiver detects an error, it throws away the packet and requests the transmitter to retransmit the same packet. If the requested packet has not arrived in a given time period, the missed packets are replaced with zero amplitude values. The variable delays that packets are subjected to as a result of this procedure are smoothed out before packets are played back so that they all appear contiguous at the receiving end. The resulting improvement in the SNR at the receiving end depends, among other things, on the maximum delay we permit and the vehicle speed, and is achieved in addition to any improvement that is possible with a specially designed coder. For example, with 4 ms long packets and 12 ms of delay, the SNR improves by about 13 dB at a vehicle speed of 35 mph and 17 dB at 12 mph.
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=577064&tag=1
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=577064&tag=1
Research Interests: Probability Theory, Packet Switching, Conflict and Error Detection, Algorith design of setillite transmissmission and signal encoding system, Signal - to - noise ratio, and 12 moreSignal Receivers, Fading (Radio), Coding Errors, RADIO SYSTEMS, MOBILE, Codes (Symbols), Reception Quality, Speech Transmission, Clustered Bit Errors, Error Detecting Codes, Noise Bursts, Packetizing Voice, and Rayleigh Fades
This paper presents the delay-throughput and buffer utilization characteristics of a few statistical multiplexers. Two of the various schemes that may be used to access the multiplexer are considered: the point-to-point access scheme... more
This paper presents the delay-throughput and buffer utilization characteristics of a few statistical multiplexers. Two of the various schemes that may be used to access the multiplexer are considered: the point-to-point access scheme where the traffic is carried between each user and the multiplexer over a separate link in a star topology, and the carrier sense multiple access protocol with collision detection (CSMA/CD) that is used over a shared communication link. Results from computer simulations show that for the n multiplied by 1 statistical multiplexer using the star topology, the delay and buffer size utilized increase exponentially with the channel utilization factor rho . The delay-throughput characteristics of a well designed multiplexer using the CSMA/CD access protocol are comparable to those of the n multiplied by 1 multiplexer based on the star topology. With the CSMA/CD protocol, as the packet size is increased, the delay normalized to the packet size, while a function of rho , first decreases and eventually tends to a limit.
http://www.scopus.com/inward/record.url?eid=2-s2.0-0023314775&partnerID=40&md5=1168204bdc6a9a29001e2619f58dffae
http://www.scopus.com/inward/record.url?eid=2-s2.0-0023314775&partnerID=40&md5=1168204bdc6a9a29001e2619f58dffae
Research Interests:
This report has explored the possibility of transmitting packetized data over a Rayleigh fading channel. The random errors due to the FM channel impairments have been ignored, and only burst errors that characterize the fading channel are... more
This report has explored the possibility of transmitting packetized data over a Rayleigh fading channel. The random errors due to the FM channel impairments have been ignored, and only burst errors that characterize the fading channel are considered. The protocol simulated is the widely used HDLC protocol which requires a frame to be retransmitted only when the remote end has detected errors in the received frame. Packets are sufficiently short so that most of them fall in the interfade time intervals. This leads to a high transmission efficiency. It is shown that the delay and throughput depend on the fade statistics. Also, for a given vehicle speed, they both improve monotonically as the packet size decreases. However, a smaller packet size increases the overhead fraction of the packet and thus reduces the effective throughput. Furthermore, there is a range of values of the packet size over which the delay is small and the efficiency high.
http://onlinelibrary.wiley.com/doi/10.1002/j.1538-7305.1986.tb00367.x/abstract
http://onlinelibrary.wiley.com/doi/10.1002/j.1538-7305.1986.tb00367.x/abstract
Research Interests:
In a microwave mobile telecommunications system, a digital message must be transmitted several times to overcome the effects of Rayleigh fades that characterize this channel, and thus ensure a high probability that the message is received... more
In a microwave mobile telecommunications system, a digital message must be transmitted several times to overcome the effects of Rayleigh fades that characterize this channel, and thus ensure a high probability that the message is received error-free. An analytic approach to an evaluation of the comparative performance of different transmission schemes in terms of the probability of a transmission failure is presented, and a basis for the design of an efficient scheme is provided. Some fade statistics that have been used are presented. The upper bounds are derived on probability of the transmission failure for three different schemes. The actual failure rates as determined in an experimental simulation are then shown for those schemes that the theoretical study predicts to be acceptable. It is shown that an efficient scheme for the Rayleigh fading channel is the block-protected one in which a message is transmitted four times, each transmission 4-ms long and spaced 4-ms apart. The spacing is obtained by interleaving a similar transmission of another message. The receiver discards a transmission if it fails the parity checks.
ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1622966
ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=1622966
Research Interests:
A characteristic of a mobile radio channel is the occurrence of correlated signal fading that results in burst errors. The use of adaptive delta modulation (ADM) based on explicit transmission of the quantizer step size was proposed... more
A characteristic of a mobile radio channel is the occurrence of correlated signal fading that results in burst errors. The use of adaptive delta modulation (ADM) based on explicit transmission of the quantizer step size was proposed earlier for speech communication over such a channel. Two other vaiable step-size delta modulation (VSDM) schemes are presented, and their performance in a mobile radio environment is discussed. One of them is the constant factor delta modulation that uses one-bit memory and produces fast and instantaneous step-size changes. The other is the digitally controlled delta modulation (DCDM) that incorporates a new step-size adaptation strategy using seven bits of memory.
http://ieeexplore.ieee.org/xpl/abstractKeywords.jsp?arnumber=1622991
http://ieeexplore.ieee.org/xpl/abstractKeywords.jsp?arnumber=1622991
Research Interests:
Many researches on PMA mixture have been conducted for the past two decades. Although addition of virgin polymers to asphalt for the purpose of enhancing the properties of asphalt over a wide temperature range in paving applications was... more
Many researches on PMA mixture have been conducted for the past two decades. Although addition of virgin polymers to asphalt for the purpose of enhancing the properties of asphalt over a wide temperature range in paving applications was contemplated quite some time ago, recycled polymer added to asphalt have also shown almost the same result in improving the road pavement performance as compared to virgin polymers This paper is a review of the use of polymers in asphalt pavement. In this study, a critical review on the history and benefits of using waste and virgin polymer in asphalt is presented followed by a review of general studies on using polymers in asphalt in order to improve the properties of pavement. (C) 2012 Elsevier Ltd. All rights reserved.
http://www.sciencedirect.com/science/article/pii/S0950061812000323
http://www.sciencedirect.com/science/article/pii/S0950061812000323
Research Interests: Performance Studies, Quality of life, Bitumen (Petrochemical Product), Polymer Blends, Pavement Engineering, and 10 morePlastics, Evaluation of water and soils contaminated with chemical mixtures in water and soils, Thermal Stability, Waste Water Treatment by adsorption process using natural polymer, High Density Polyethylene, STONE MASTIC ASPHALT, Polymer-modified, Virgin Polymer, Modified Bitumens, and Flexible Pavements
Uncontrolled stormwater runoff not only creates drainage problems and flash floods but also presents a considerable threat to water quality and the environment. These problems can, to a large extent, be reduced by a type of stormwater... more
Uncontrolled stormwater runoff not only creates drainage problems and flash floods but also presents a considerable threat to water quality and the environment. These problems can, to a large extent, be reduced by a type of stormwater management approach employing permeable pavement systems (PPS) in urban, industrial and commercial areas, where frequent problems are caused by intense undrained stormwater. PPS could be an efficient solution for sustainable drainage systems, and control water security as well as renewable energy in certain cases. Considerable research has been conducted on the function of PPS and their improvement to ensure sustainable drainage systems and water quality. This paper presents a review of the use of permeable pavement for different purposes. The paper focuses on drainage systems and stormwater runoff quality from roads, driveways, rooftops and parking lots. PPS are very effective for stormwater management and water reuse. Moreover, geotextiles provide additional facilities to reduce the pollutants from infiltrate runoff into the ground, creating a suitable environment for the biodegradation process. Furthermore, recently, ground source heat pumps and PPS have been found to be an excellent combination for sustainable renewable energy. In addition, this study has identified several gaps in the present state of knowledge on PPS and indicates some research needs for future consideration. © 2013 Taylor & Francis.
http://www.tandfonline.com/doi/abs/10.1080/09593330.2013.782573#.UrDsvSeA_5M
http://www.tandfonline.com/doi/abs/10.1080/09593330.2013.782573#.UrDsvSeA_5M
Research Interests: Performance Studies, Water quality, Water resources, Sustainable Drainage, Modeling and Simulation, and 10 moreRemoval Of Heavy Metals In Contaminated Soils, Porous Pavement, (i) Adsorption study: Removal of organic and inorganic pollutants by inexpensive adsorbents, Geotextiles, Permeable Pavements, Urban Runoff, Ground Source Heat Pumps (Gshp), Heat-pump Systems, Neural-networks, and North-carolina
Crumb rubber modification has been proven to enhance the properties of pure bitumen. This paper looks at some of the international standards for producing crumb rubber modified bitumen (CRMB) and reviews the effect of crumb rubber to the... more
Crumb rubber modification has been proven to enhance the properties of pure bitumen. This paper looks at some of the international standards for producing crumb rubber modified bitumen (CRMB) and reviews the effect of crumb rubber to the rheology of crumb rubber modified bitumen. The review shows that the rheology of CRMB depends on internal factors such as crumb rubber quantity, particle size, and pure bitumen composition, and external factors such as the mixing time, temperature, and also the modification technique. These factors govern the swelling process of crumb rubber particles that lead to the increase of viscosity of the modified bitumen. However, the mixing temperature and duration can cause rubber particles to depolymerize and subsequently cause loss of viscosity. Crumb rubber modification also improves the properties of bitumen by increasing the storage and loss modulus and enhancing the high and low temperature susceptibility. The effect of crumb rubber to aging properties of CRMB is also discussed. Finally several techniques of chemical modification to terminal blends of CRMB and the subsequent improvement to the settling property of CRMB are explained. © 2013 Mohd Rasdan Ibrahim et al.
http://www.hindawi.com/journals/amse/2013/415246/abs/
http://www.hindawi.com/journals/amse/2013/415246/abs/
Research Interests: Elasticity (Solid Mechanics), Chemical Modification of Cellulose, Viscosity, Recycled Tire Rubber, Lake Temperature and Mixing Regimes, and 9 moreInternational standards, Stochastic Ordering and Aging Properties using TTT, Recycling Waste Bituminous Materials, Settling Properties, Internal Factors, Low-temperature Susceptibility, Storage and Loss Modulus, Swelling Process, and Rubber Additions
Intersections are bottleneck in the highway networks and critical determinant of system's capacity and safety. Recently, several countdown timers had been installed at intersections in Kuala Lumpur and some other cities in Malaysia. The... more
Intersections are bottleneck in the highway networks and critical determinant of system's capacity and safety. Recently, several countdown timers had been installed at intersections in Kuala Lumpur and some other cities in Malaysia. The function of these timers is to aid drivers to judge the amount of time left for them to get the green signal for moving (starting) their vehicles as well as the amount of green time available for them to proceed across the intersection or to stop safely before the signal turns red. This advance information is supposed to help drivers in reducing their initial delay, especially for the first few vehicles and improving safety level. In the present research six intersections, three with count down timers and three with no-count down timer are analyzed to study the effect of count down timer on driver behavior, intersection approach headway and safety levels. The study suggests that countdown timer has got little effect on initial delay but the effect on headway is significant. The violation of traffic light by the drivers for countdown and normal signal is also compared. © 2008 Science Publications.
http://thescipub.com/abstract/10.3844/ajassp.2008.479.482
http://thescipub.com/abstract/10.3844/ajassp.2008.479.482
Research Interests:
Grouted Macadam composite pavement (GMCP) is generally a composite pavement which is manufactured by preparing a highly workable fluid mortar which is specially designed with a very high early and 28 day strength (1 day - 45 MPa, 28 day -... more
Grouted Macadam composite pavement (GMCP) is generally a composite pavement which is manufactured by preparing a highly workable fluid mortar which is specially designed with a very high early and 28 day strength (1 day - 45 MPa, 28 day - 105 MPa) by filling the flowing fluid mortar into a very open porous asphalt skeleton (25-32% Voids in Mix - VIM). The combination of both components will produce a semi-rigid pavement or GMCP which has the best features of both rigid concrete and flexible bituminous pavement where it will replace the conventional wearing course. This paper will investigate the significance difference of GMCP produced by the 3 different aggregate gradations by Road Engineering Association of Malaysia (REAM) in volumetric properties, durability and strength. The best quality fluid grout was chosen to fill the porous asphalt skeleton and GMCP was subjected for compression test, VIM and indirect tensile test (IDT) to check on its performance. The results show that the 3 different aggregate gradations significantly affect the volumetric properties, durability and strength. Furthermore it will also help in reducing pollution and helps with the current environmental problems. © 2010 IEEE.
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5653996
http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5653996
Research Interests: Environmental Engineering, Malaysia, Highway engineering, Fluids, Environmental Problems, and 23 moreDurability of Concrete, Road Safety, Traffic Enforcement, Driver Education, Highway Engineering, Aggregates, Permeation Grouting, Lime mortars and plasters, Asphalt Pavements, Behaviour of frames with semi-rigid connections, Pavements, Fatigue, Tensile, Compression Testing, Tensile testing, porous Asphalt, Innovative Materials and Sustainable Concrete Construction, Fluid Grout, Grouted Macadam Composite Pavement, Aggregate Gradations, Bituminous Pavement, Composite Pavements, Flowing Fluid, Indirect Tensile Test, Porous Asphalts, Volumetric Properties, Wearing Course, and Volumetric Analysis
The degree of sorption of dihenzodioxin (DBD) to pulp varies with the lignin content of the latter. DBD is rapidly degraded by chlorine dioxide in aqueous solution but is much more stable in the presence of semibleached pulp, suggesting... more
The degree of sorption of dihenzodioxin (DBD) to pulp varies with the lignin content of the latter. DBD is rapidly degraded by chlorine dioxide in aqueous solution but is much more stable in the presence of semibleached pulp, suggesting that sorbed DBD is far less reactive than the freely dissolved material. Degradation products include the 2-chloro derivative and products inextricably bound to pulp. © 1992 American Chemical Society.
pubs.acs.org/doi/pdf/10.1021/es00031a007
pubs.acs.org/doi/pdf/10.1021/es00031a007
Research Interests:
This paper presents an efficient and fast encoding of still images using feedforward neural network technique for codebook search. The image to be coded is first clustered into a small subset of neighboring images and then the neural... more
This paper presents an efficient and fast encoding of still images using feedforward neural network technique for codebook search. The image to be coded is first clustered into a small subset of neighboring images and then the neural network-based encoder is used to find the best matching code sequences in the codebook. This subset is then used as a candidate set and an exhaustive search is then performed within this subset to find an optimal code sequence which minimizes the perceptual error between coded and decoded images. In this work, a generic codebook is developed using non-causal Differential Pulse Coded Modulation (DPCM) with residual mean removal and vector quantization using Linde, Buzo and Gray (LBG) method. The codebook is analyzed to identify a pattern in the codebook. This pattern is used to train a neural network to obtain the approximate index of the pattern in the codebook. Then, an extensive search is done around this approximate position identified by the neural network to obtain the nearest neighbor of the pattern. Since the candidate set is usually much smaller that the whole code book, there is a substantial saving in codebook search time for coding an image as compared to the traditional method using full codebook search by LBG algorithm.
ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=845604
ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=845604