The Urban Heat Island Effect（UHI）has now become a commonly observed phenomenon worldwide.Indeed,it has become a significant environmental effect of urbanisation.In Malaysia,research results showed that UHI effects a...The Urban Heat Island Effect（UHI）has now become a commonly observed phenomenon worldwide.Indeed,it has become a significant environmental effect of urbanisation.In Malaysia,research results showed that UHI effects are very evident in several cities such as Kuala Lumpur and Putrajaya.UHI effect has long been observed to cause temperature of cities.展开更多
A computational fluid dynamics(CFD)study of the impact characteristics and stagnation formation on a solid target surface by an abrasive waterjet at supersonic velocities is presented to understand the impact process....A computational fluid dynamics(CFD)study of the impact characteristics and stagnation formation on a solid target surface by an abrasive waterjet at supersonic velocities is presented to understand the impact process.A CFD model is developed and verified by experimental water and particle velocities and then used to simulate the jet impact process.The trends of the stagnation formation and its effect on the jet flow with respect to the jetting and impacting parameters are amply discussed.It is found that stagnation formation at the impact site increases with an increase in the impact time,nozzle standoff distance and nozzle diameter,while the initial peak velocity at the nozzle exit has little effect on the size of the stagnation zone.It is shown that stagnation markedly changes the water and particle flow direction,so that the particle impact angle is varied and the jet impact area is enlarged.The jet structure may be classified to have a free jet flow region,a jet deflection region with a stagnation zone and a wall jet region.Furthermore,the stagnation affects significantly the waterjet and particle energy transferred to the target surface.The average particle velocity across the jet is reduced by approximately one third due to the damping effect of the stagnation under the conditions considered in this study.展开更多
The impact attenuator is an essential system in both race cars and urban vehicles.The structure of animpact attenuator serves as a safety barrier between the impacted surface and the driver in an accident.Attenuator m...The impact attenuator is an essential system in both race cars and urban vehicles.The structure of animpact attenuator serves as a safety barrier between the impacted surface and the driver in an accident.Attenuator materials tend to have a high price;thus,alternative materials were explored in the currentwork,i.e.,used cans from food and beverage containers.The study deployed a nonlinear finite elementalgorithm to calculate a series of impacts on the attenuator structures.The thickness of the cans andvelocity of the impact were considered as the main parameters.Analysis results concluded that the at-tenuator’s average energy was 16000 J for a can thickness of 1 mm.This value is more than two times the0.5 mm thick used cans.The attenuator’s new design was then matched with an attenuator regulation,and the results surpassed the standard value of 7350 J.展开更多
基金funded by Grand Challenge-SUS(Sustainability Science)Grants GC002C-15SUS and GC002A-15SUS
文摘The Urban Heat Island Effect（UHI）has now become a commonly observed phenomenon worldwide.Indeed,it has become a significant environmental effect of urbanisation.In Malaysia,research results showed that UHI effects are very evident in several cities such as Kuala Lumpur and Putrajaya.UHI effect has long been observed to cause temperature of cities.
基金The project was financially supported by the Australian Research Council(ARC)under the Discovery-Projects scheme.K T would like to thank the Royal Thai Government for providing a PhD scholarship for this study.
文摘A computational fluid dynamics(CFD)study of the impact characteristics and stagnation formation on a solid target surface by an abrasive waterjet at supersonic velocities is presented to understand the impact process.A CFD model is developed and verified by experimental water and particle velocities and then used to simulate the jet impact process.The trends of the stagnation formation and its effect on the jet flow with respect to the jetting and impacting parameters are amply discussed.It is found that stagnation formation at the impact site increases with an increase in the impact time,nozzle standoff distance and nozzle diameter,while the initial peak velocity at the nozzle exit has little effect on the size of the stagnation zone.It is shown that stagnation markedly changes the water and particle flow direction,so that the particle impact angle is varied and the jet impact area is enlarged.The jet structure may be classified to have a free jet flow region,a jet deflection region with a stagnation zone and a wall jet region.Furthermore,the stagnation affects significantly the waterjet and particle energy transferred to the target surface.The average particle velocity across the jet is reduced by approximately one third due to the damping effect of the stagnation under the conditions considered in this study.
文摘The impact attenuator is an essential system in both race cars and urban vehicles.The structure of animpact attenuator serves as a safety barrier between the impacted surface and the driver in an accident.Attenuator materials tend to have a high price;thus,alternative materials were explored in the currentwork,i.e.,used cans from food and beverage containers.The study deployed a nonlinear finite elementalgorithm to calculate a series of impacts on the attenuator structures.The thickness of the cans andvelocity of the impact were considered as the main parameters.Analysis results concluded that the at-tenuator’s average energy was 16000 J for a can thickness of 1 mm.This value is more than two times the0.5 mm thick used cans.The attenuator’s new design was then matched with an attenuator regulation,and the results surpassed the standard value of 7350 J.
