In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high i...In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high identification to discontinuity are used to the numerical reconstruction of part of an actual hemispherical blast-wave flow field by properly adjusting the moving bounary conditions of a piston. This method is simple and reliable. It is suitable to the evaluation of effects of the blast-wave flow field away from the explosion center.展开更多
The simulation performance over complex building clusters of a wind simulation model（Wind Information Field Fast Analysis model, WIFFA） in a micro-scale air pollutant dispersion model system（Urban Microscale Air Po...The simulation performance over complex building clusters of a wind simulation model（Wind Information Field Fast Analysis model, WIFFA） in a micro-scale air pollutant dispersion model system（Urban Microscale Air Pollution dispersion Simulation model, UMAPS） is evaluated using various wind tunnel experimental data including the CEDVAL（Compilation of Experimental Data for Validation of Micro-Scale Dispersion Models） wind tunnel experiment data and the NJU-FZ experiment data（Nanjing University-Fang Zhuang neighborhood wind tunnel experiment data）. The results show that the wind model can reproduce the vortexes triggered by urban buildings well, and the flow patterns in urban street canyons and building clusters can also be represented. Due to the complex shapes of buildings and their distributions, the simulation deviations/discrepancies from the measurements are usually caused by the simplification of the building shapes and the determination of the key zone sizes. The computational efficiencies of different cases are also discussed in this paper. The model has a high computational efficiency compared to traditional numerical models that solve the Navier–Stokes equations, and can produce very high-resolution（1–5 m） wind fields of a complex neighborhood scale urban building canopy（～ 1 km ×1km） in less than 3 min when run on a personal computer.展开更多
Communication delays within connected and autonomous vehicles(CAVs)pose significant risks.It is imperative to address these issues to ensure the safe and effective operation of CAVs.However,the exploration of communic...Communication delays within connected and autonomous vehicles(CAVs)pose significant risks.It is imperative to address these issues to ensure the safe and effective operation of CAVs.However,the exploration of communication delays on CAV operations and their energy use remains sparse in the literature.To fill the research gap,this study leverages the facilities at America Center of Mobility(ACM)Smart City Test Center to implement and evaluate a CAV merging control algorithm through vehicle-in-the-loop testing.This study aims at achieving three main objectives:(1)develop and implement a CAV merging control strategy in the experimental test bed through vehicle-in-the-loop testing,(2)propose analytical models to quantify the impacts of communication delay on the variability of CAV speed and energy consumption based on field experiment data,and(3)create a predictive model for energy usage considering various CAV attributes and dynamics,e.g.,speed,acceleration,yaw rate,and communication delays.To our knowledge,this is one of the first attempts at evaluating the impacts of communication delays on CAV merging operational control with field data,making critical advancement in the field.The results suggest that communication delay has a more substantial effect on energy consumption under high-speed volatility compared to low-speed volatility.Among all factors examined,acceleration is the dominant characteristic that influences energy usage.It also revealed that even minor improvements in communication delay can yield tangible improvements in energy efficiency.The results provide guidance on CAV field experiments and the influence of communication delays on CAV operation and energy consumption.展开更多
文摘In this paper, on the basis of experimental data of two kinds of chemical explosions, the piston-pushing model of spherical blast-waves and the second-order Godunov-type scheme of finite difference methods with high identification to discontinuity are used to the numerical reconstruction of part of an actual hemispherical blast-wave flow field by properly adjusting the moving bounary conditions of a piston. This method is simple and reliable. It is suitable to the evaluation of effects of the blast-wave flow field away from the explosion center.
基金supported by the China Special Fund for Meteorological Research in the Public Interest(Grant No.GYHY201106049)the National Natural Science Foundation of China(Grant Nos.51538005 and 41375014)the Jiangsu Collaborative Innovation Center for Climate Change,China
文摘The simulation performance over complex building clusters of a wind simulation model（Wind Information Field Fast Analysis model, WIFFA） in a micro-scale air pollutant dispersion model system（Urban Microscale Air Pollution dispersion Simulation model, UMAPS） is evaluated using various wind tunnel experimental data including the CEDVAL（Compilation of Experimental Data for Validation of Micro-Scale Dispersion Models） wind tunnel experiment data and the NJU-FZ experiment data（Nanjing University-Fang Zhuang neighborhood wind tunnel experiment data）. The results show that the wind model can reproduce the vortexes triggered by urban buildings well, and the flow patterns in urban street canyons and building clusters can also be represented. Due to the complex shapes of buildings and their distributions, the simulation deviations/discrepancies from the measurements are usually caused by the simplification of the building shapes and the determination of the key zone sizes. The computational efficiencies of different cases are also discussed in this paper. The model has a high computational efficiency compared to traditional numerical models that solve the Navier–Stokes equations, and can produce very high-resolution（1–5 m） wind fields of a complex neighborhood scale urban building canopy（～ 1 km ×1km） in less than 3 min when run on a personal computer.
基金US Department of Energy(DOE)under the project EEMS082:Validation of Connected and Automated Mobility System.
文摘Communication delays within connected and autonomous vehicles(CAVs)pose significant risks.It is imperative to address these issues to ensure the safe and effective operation of CAVs.However,the exploration of communication delays on CAV operations and their energy use remains sparse in the literature.To fill the research gap,this study leverages the facilities at America Center of Mobility(ACM)Smart City Test Center to implement and evaluate a CAV merging control algorithm through vehicle-in-the-loop testing.This study aims at achieving three main objectives:(1)develop and implement a CAV merging control strategy in the experimental test bed through vehicle-in-the-loop testing,(2)propose analytical models to quantify the impacts of communication delay on the variability of CAV speed and energy consumption based on field experiment data,and(3)create a predictive model for energy usage considering various CAV attributes and dynamics,e.g.,speed,acceleration,yaw rate,and communication delays.To our knowledge,this is one of the first attempts at evaluating the impacts of communication delays on CAV merging operational control with field data,making critical advancement in the field.The results suggest that communication delay has a more substantial effect on energy consumption under high-speed volatility compared to low-speed volatility.Among all factors examined,acceleration is the dominant characteristic that influences energy usage.It also revealed that even minor improvements in communication delay can yield tangible improvements in energy efficiency.The results provide guidance on CAV field experiments and the influence of communication delays on CAV operation and energy consumption.
