A parallel algorithm suitable for simulating multi-sized particle systems and multi- phase fluid systems is proposed based on macro-scale pseudo-particle modeling (MaPPM). The algorithm employs space-decomposition of ...A parallel algorithm suitable for simulating multi-sized particle systems and multi- phase fluid systems is proposed based on macro-scale pseudo-particle modeling (MaPPM). The algorithm employs space-decomposition of the computational load among the processing ele- ments (PEs) and multi-level cell-subdivision technique for particle indexing. In this algorithm, a 2D gas-solid system is simulated with the temporal variations of drags on solids, inter-phase slip velocities and solids concentration elaborately monitored. Analysis of the results shows that the algorithm is of good parallel efficiency and scalability, demonstrating the unique advantage of MaPPM in simulating complex flows.展开更多
This study fully addressed the modifiable areal unit problem （MAUP） that was well-known in geography but generally ignored by safety analysis. The basic issue of MAUP was introduced firstly with a case study to expl...This study fully addressed the modifiable areal unit problem （MAUP） that was well-known in geography but generally ignored by safety analysis. The basic issue of MAUP was introduced firstly with a case study to explicitly demonstrate the existence of the problem in macro level crash modeling, and then four potential strategies, i.e., using disaggregate data as possible, capturing spatial non-stationarity, designing optimal zoning systems, conducting sensitivity analysis to report the scope and magnitude of MAUP, were proposed and illustrated in an integrated way, followed by the future research directions. Results revealed that more efforts are desired to calibrate the state-of-art modeling technique at various levels of aggregation based on spatial homogeneity in traffic safety, transport characteristics, and demographical factors. The awareness of this problem in traffic safety domain is expected to the delineation of basic spatial units （e.g. the traffic safety analysis zones）, as well as to provide new insights into the nature of MAUP in statistics and geography.展开更多
基金浙江省新苗人才计划资助(“XinMiao Project of Science and Technology Department of Zhejiang Province”)浙江省自然科学基金资助项目(Zhejiang Province Natural Science Foundation)(Y107055)
基金This work was supported by the National Key Program for Developing Basic Sciences(Grant No.G1999032801)the National Natural Science Foundation of China(Grant Nos.20336040and 20221603)the Chinese Academy of Sciences(Grant No.INF105-SCE-2-07).
文摘A parallel algorithm suitable for simulating multi-sized particle systems and multi- phase fluid systems is proposed based on macro-scale pseudo-particle modeling (MaPPM). The algorithm employs space-decomposition of the computational load among the processing ele- ments (PEs) and multi-level cell-subdivision technique for particle indexing. In this algorithm, a 2D gas-solid system is simulated with the temporal variations of drags on solids, inter-phase slip velocities and solids concentration elaborately monitored. Analysis of the results shows that the algorithm is of good parallel efficiency and scalability, demonstrating the unique advantage of MaPPM in simulating complex flows.
基金Natural Science Foundation of China (No. 71371192)the Research Fund for Fok Ying Tong Education Foundation of Hong Kong (No. 142005)Science Fund for Outstanding Young Scholars of Hunan Province (No. 2015JJ1017)
文摘This study fully addressed the modifiable areal unit problem （MAUP） that was well-known in geography but generally ignored by safety analysis. The basic issue of MAUP was introduced firstly with a case study to explicitly demonstrate the existence of the problem in macro level crash modeling, and then four potential strategies, i.e., using disaggregate data as possible, capturing spatial non-stationarity, designing optimal zoning systems, conducting sensitivity analysis to report the scope and magnitude of MAUP, were proposed and illustrated in an integrated way, followed by the future research directions. Results revealed that more efforts are desired to calibrate the state-of-art modeling technique at various levels of aggregation based on spatial homogeneity in traffic safety, transport characteristics, and demographical factors. The awareness of this problem in traffic safety domain is expected to the delineation of basic spatial units （e.g. the traffic safety analysis zones）, as well as to provide new insights into the nature of MAUP in statistics and geography.
