In this paper, we propose a new cellular automata model to simulate the railway traffic at station. Based on NaSch model, the proposed station model is composed of the main track and the siding track. Two different sc...In this paper, we propose a new cellular automata model to simulate the railway traffic at station. Based on NaSch model, the proposed station model is composed of the main track and the siding track. Two different schemes for trains passing through station are considered. One is the scheme of "pass by the main track, start and stop by the siding track". The other is the scheme of "two tracks play the same role". We simulate the train movement using the proposed model and analyze the traffic flow at station. The simulation results demonstrate that the proposed cellular automata model can be successfully used for the simulations of railway traffic. Some characteristic behaviors of railway traffic flow can be reproduced. Moreover, the simulation values of the minimum headway are close to the theoretical values. This result demonstrates the dependability and availability of the proposed model.展开更多
Fire-driven flow analysis in the underground subway station has been performed with various main tunnel ventilations. Shin-gum-ho station (depth: 46 m) in Seoul is selected as a simulation model. The ventilation mo...Fire-driven flow analysis in the underground subway station has been performed with various main tunnel ventilations. Shin-gum-ho station (depth: 46 m) in Seoul is selected as a simulation model. The ventilation mode is assumed to be emergency state. Various main tunnel ventilations are applied to operate in a proper way for helping of smoke exhaustion in platform. The entire station is covered for simulation. Ventilation diffusers are modeled as 95 square shapes of 0.6 m × 0.6 m in the lobby and as 222 square shapes of 0.6 m × 0.6 m and four rectangular shapes of 1.2 m × 0.8 m in the platform. The total of 7.5 million grids is generated and whole domain is divided to 22 blocks for MPI (massage passing interface) efficiency of calculation. LES (large eddy simulation) is applied to solve the momentum equation. Smagorinsky model (Cs = 0.2) is used as SGS (subgrid scale) model. The distribution of CO (carbon monoxide) is calculated for various capacity of main tunnel ventilation and compared with each other.展开更多
With the rapid development of computer graphics, distributed-computing and Internet, it is possible to achieve Internet-based virtual city. This paper dwells on the method of the terrain and its feature modeling and c...With the rapid development of computer graphics, distributed-computing and Internet, it is possible to achieve Internet-based virtual city. This paper dwells on the method of the terrain and its feature modeling and complex entity modeling in the virtual city. Then, discusses the method for Internet-based virtual city 3D visualization and the design of the Browser/Server architecture of the system of virtual city in the network environment. Finally, Java and Java 3D are used to show an experiment example, and the related conclusion about Internet-based virtual city 3D displaying and the client-side interactive operation is given.展开更多
The performance of a digging shovel mainly depends on the style of the shovel, while the conventional experiment methods always suffer from the problems of high lost and long period. Aiming at these problems and the c...The performance of a digging shovel mainly depends on the style of the shovel, while the conventional experiment methods always suffer from the problems of high lost and long period. Aiming at these problems and the characteristic that soil is composed of countless small particles, dynamic simulation analysis was performed on the resistance to a bionic digging shovel and crushing rate of the soil during the normal working process of the bionic digging shovel by EDEM through numerical simulation, calculation and comparison. The results showed that compared with the ordinary shovel, the average drag-reducing rate in the X direction was 10.41%, and the average drag-reducing rate in the Y direction was 16.28%, and the soil crushing rate was improved by 2.67%. Therefore, the bionic digging shovel has certain superiority and extension value in structure and performance. Moreover, this analysis case fully demonstrates the unique advantage of DEM method and its generalizability, and provides certain reference for similar studies.展开更多
In this letter,we propose a novel three-dimensional conceptual model for an emerging service-oriented simulation paradigm. The model can be used as a guideline or an analytic means to find the potential and possible f...In this letter,we propose a novel three-dimensional conceptual model for an emerging service-oriented simulation paradigm. The model can be used as a guideline or an analytic means to find the potential and possible future directions of the current simulation frameworks. In particular, the model inspects the crossover between the disciplines of modeling and simulation, service-orientation,and software/systems engineering. Finally, two specific simulation frameworks are studied as examples.展开更多
Multi-decadal high resolution climate change simulations over East Asia were performed by using The Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3), nested within the NA...Multi-decadal high resolution climate change simulations over East Asia were performed by using The Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3), nested within the NASA/NCAR global model FvGCM/CCM3. Two sets of simulations were conducted at 20-km grid spacings, one for present day (1961-1990) and one for the future climate (2071-2100, IPCC A2 scenario). Simulations of present climate conditions over China by RegCM3 and FvGCM were compared against observations to assess the model performance. Results showed that both models repro- duced the observed spatial structure of 500 hPa height, surface air temperature and precipitation. Compared with FvGCM, RegCM3 provided increasing spatial detail of surface variables. Furthermore, RegCM3 improved the simulation of monsoon precipitation over the region. Changes in the mean temperature and precipitation were analyzed and compared between the two models. Significant warming in the end of the 21st century was simulated by both models in December-January-February (DJF), June-July-August (JJA), and the annual mean. In DJF, greater warming was simulated by FvGCM over Northeast and Northwest China, as well as the Tibetan Plateau, compared with RegCM. In JJA, RegCM3 simulated greater warming over northern China, Inner Mongolia, Northwest China, and the Tibetan Plateau. Simulated changes in DJF precipitation showed similar spatial patterns between the two models. In JJA, while FvGCM projected a prevailing increase of monsoon precipitation over China, which is in agreement with other global models, RegCM3 projected extended areas of decreased precipitation. Changes in the variability for annual mean temperature and precipitation also are presented.展开更多
Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this paper.The properties,particularly the properties of gas seals of ...Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this paper.The properties,particularly the properties of gas seals of the engine are simulated using a simulation program developed for this case,and the results are utilized in preliminary main design parameter selection.The engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology,Tampere University of Technology,and Lappeenranta University of Technology.Because of the contact-free labyrinth seal used in the piston,the efficiency of the motor is lower than the efficiency of a conventional motor with oil lubricated piston rings.On the other hand,the lack of bearing losses,and the lack of losses associated with a crankshaft system and a gearbox,as well as the lack of lubrication oil expenses,compensates this effect.As a net result,this new motor would perform slightly better than the conventional one.Being completely oil-free,it is very environmentally friendly,and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors.展开更多
基金supported by National Natural Science Foundation of China under Grant Nos. 60634010 and 60776829Key Technology Research of Train Control System,and Urban Rail Transit Automation and Control Beijing Municipal Government Key Laboratory
文摘In this paper, we propose a new cellular automata model to simulate the railway traffic at station. Based on NaSch model, the proposed station model is composed of the main track and the siding track. Two different schemes for trains passing through station are considered. One is the scheme of "pass by the main track, start and stop by the siding track". The other is the scheme of "two tracks play the same role". We simulate the train movement using the proposed model and analyze the traffic flow at station. The simulation results demonstrate that the proposed cellular automata model can be successfully used for the simulations of railway traffic. Some characteristic behaviors of railway traffic flow can be reproduced. Moreover, the simulation values of the minimum headway are close to the theoretical values. This result demonstrates the dependability and availability of the proposed model.
文摘Fire-driven flow analysis in the underground subway station has been performed with various main tunnel ventilations. Shin-gum-ho station (depth: 46 m) in Seoul is selected as a simulation model. The ventilation mode is assumed to be emergency state. Various main tunnel ventilations are applied to operate in a proper way for helping of smoke exhaustion in platform. The entire station is covered for simulation. Ventilation diffusers are modeled as 95 square shapes of 0.6 m × 0.6 m in the lobby and as 222 square shapes of 0.6 m × 0.6 m and four rectangular shapes of 1.2 m × 0.8 m in the platform. The total of 7.5 million grids is generated and whole domain is divided to 22 blocks for MPI (massage passing interface) efficiency of calculation. LES (large eddy simulation) is applied to solve the momentum equation. Smagorinsky model (Cs = 0.2) is used as SGS (subgrid scale) model. The distribution of CO (carbon monoxide) is calculated for various capacity of main tunnel ventilation and compared with each other.
文摘With the rapid development of computer graphics, distributed-computing and Internet, it is possible to achieve Internet-based virtual city. This paper dwells on the method of the terrain and its feature modeling and complex entity modeling in the virtual city. Then, discusses the method for Internet-based virtual city 3D visualization and the design of the Browser/Server architecture of the system of virtual city in the network environment. Finally, Java and Java 3D are used to show an experiment example, and the related conclusion about Internet-based virtual city 3D displaying and the client-side interactive operation is given.
文摘The performance of a digging shovel mainly depends on the style of the shovel, while the conventional experiment methods always suffer from the problems of high lost and long period. Aiming at these problems and the characteristic that soil is composed of countless small particles, dynamic simulation analysis was performed on the resistance to a bionic digging shovel and crushing rate of the soil during the normal working process of the bionic digging shovel by EDEM through numerical simulation, calculation and comparison. The results showed that compared with the ordinary shovel, the average drag-reducing rate in the X direction was 10.41%, and the average drag-reducing rate in the Y direction was 16.28%, and the soil crushing rate was improved by 2.67%. Therefore, the bionic digging shovel has certain superiority and extension value in structure and performance. Moreover, this analysis case fully demonstrates the unique advantage of DEM method and its generalizability, and provides certain reference for similar studies.
基金Project (Nos.60574056 and 60674069) supported by the National Natural Science Foundation of China
文摘In this letter,we propose a novel three-dimensional conceptual model for an emerging service-oriented simulation paradigm. The model can be used as a guideline or an analytic means to find the potential and possible future directions of the current simulation frameworks. In particular, the model inspects the crossover between the disciplines of modeling and simulation, service-orientation,and software/systems engineering. Finally, two specific simulation frameworks are studied as examples.
基金supported by the National Basic Research Program of China (Grant No. 2009CB421407)the R & D Special Fund for Public Welfare (Grant Nos. Industry Meteorology-GYHY200806010 and Forestry-200804001)
文摘Multi-decadal high resolution climate change simulations over East Asia were performed by using The Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model (RegCM3), nested within the NASA/NCAR global model FvGCM/CCM3. Two sets of simulations were conducted at 20-km grid spacings, one for present day (1961-1990) and one for the future climate (2071-2100, IPCC A2 scenario). Simulations of present climate conditions over China by RegCM3 and FvGCM were compared against observations to assess the model performance. Results showed that both models repro- duced the observed spatial structure of 500 hPa height, surface air temperature and precipitation. Compared with FvGCM, RegCM3 provided increasing spatial detail of surface variables. Furthermore, RegCM3 improved the simulation of monsoon precipitation over the region. Changes in the mean temperature and precipitation were analyzed and compared between the two models. Significant warming in the end of the 21st century was simulated by both models in December-January-February (DJF), June-July-August (JJA), and the annual mean. In DJF, greater warming was simulated by FvGCM over Northeast and Northwest China, as well as the Tibetan Plateau, compared with RegCM. In JJA, RegCM3 simulated greater warming over northern China, Inner Mongolia, Northwest China, and the Tibetan Plateau. Simulated changes in DJF precipitation showed similar spatial patterns between the two models. In JJA, while FvGCM projected a prevailing increase of monsoon precipitation over China, which is in agreement with other global models, RegCM3 projected extended areas of decreased precipitation. Changes in the variability for annual mean temperature and precipitation also are presented.
基金Project is financed by the Technology Development Center of Finland (Tekes)
文摘Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this paper.The properties,particularly the properties of gas seals of the engine are simulated using a simulation program developed for this case,and the results are utilized in preliminary main design parameter selection.The engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology,Tampere University of Technology,and Lappeenranta University of Technology.Because of the contact-free labyrinth seal used in the piston,the efficiency of the motor is lower than the efficiency of a conventional motor with oil lubricated piston rings.On the other hand,the lack of bearing losses,and the lack of losses associated with a crankshaft system and a gearbox,as well as the lack of lubrication oil expenses,compensates this effect.As a net result,this new motor would perform slightly better than the conventional one.Being completely oil-free,it is very environmentally friendly,and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors.