Regenerative braking was the process of converting the kinetic energy and potential energy, which were stored in the vehicle body when vehicle braked or went downhill, into electrical energy and storing it into batter...Regenerative braking was the process of converting the kinetic energy and potential energy, which were stored in the vehicle body when vehicle braked or went downhill, into electrical energy and storing it into battery. The problem on how to distribute braking forces of front wheel and rear wheel for electric vehicles with four-wheel drive was more complex than that for electric vehicles with front-wheel drive or rear-wheel drive. In this work, the frictional braking forces distribution curve of front wheel and rear wheel is determined by optimizing the braking force distribution curve of hydraulic proportional-adjustable valve, and then the safety brake range is obtained correspondingly. A new braking force distribution strategy based on regenerative braking strength continuity is proposed to solve the braking force distribution problem for electric vehicles with four-wheel drive. Highway fuel economy test(HWFET) driving condition is used to provide the speed signals, the braking force equations of front wheel and rear wheel are expressed with linear equations. The feasibility, effectiveness, and practicality of the new braking force distribution strategy based on regenerative braking strength continuity are verified by regenerative braking strength simulation curve and braking force distribution simulation curves of front wheel and rear wheel. The proposed strategy is simple in structure, easy to be implemented and worthy being spread.展开更多
Currently, most efficient algorithms for force-closure analysis and dynamic force distribution utilize linear programming, but friction models are nonlinear. Substituting polyhedral cones for circular cones of Coulomb...Currently, most efficient algorithms for force-closure analysis and dynamic force distribution utilize linear programming, but friction models are nonlinear. Substituting polyhedral cones for circular cones of Coulomb friction realizes the linearization of the frictional point contact constraint. So far, however, there is no approach to soft finger contact. This paper present such an approach. Then the foregoing algorithms can be extended to grasping with soft finger contact. Herein an optimal force distribution algorithm for soft multifingered grasps is developed with an illustrative example.展开更多
This study applies ArcGIS to analyze the spatiotemporal distribution of cultural sites in the Ill River Valley in northwestern China. It explores relationships between the sites＇ spatiotemporal evolutionary character...This study applies ArcGIS to analyze the spatiotemporal distribution of cultural sites in the Ill River Valley in northwestern China. It explores relationships between the sites＇ spatiotemporal evolutionary characteristics, human history, and the natural environment. The results indicate that the numbers and proportions of the sites, and the frequency of their oc- currence, exhibited an inverted V-shaped change trend during six historical periods. The ＂high in the east and low in the west＂ spatial distribution pattern of the first three periods shifted to the one the ＂high in the west and low in the east＂ during the latter three periods, demonstrating a change in the spatial center of gravity of human activities. The sites were mainly distributed on slopes of grades 1-5, with their proportions increasing from 75% during the Spring and Autumn Period （770 BC-476 BC）-Qin Dynasty （221 BC-207 BC） to 93.75% during the Qing Dynasty-Modern period. The concentrated distribution of site elevations shifted from grades 4-8 during the Spring and Autumn Period-Qin Dynasty, and the Western Han （206 BC-8）-Southern and Northern Dynasties （420-589）, to grades 1-4 during the latter three periods. The number of sites showed a shifting trend from high-elevation mountains and hills to low-elevation plains, and from high slopes to low slopes. In particular, the sites exhibited a special ＂moist＂ evolutionary pattern of migration from middle and upstream areas to downstream areas, as opposed to the migration pattern of sites located in typical arid areas. The study also considered factors influencing the distribution and spatiotemporal evolution of cultural sites, notably, human factors and natural factors.展开更多
基金Project(JS-102)supported by the National Key Science and Technological Program of China for Electric VehiclesProject supported by Jilin University "985 Project" Engineering Bionic Technology Innovation Platform,China
文摘Regenerative braking was the process of converting the kinetic energy and potential energy, which were stored in the vehicle body when vehicle braked or went downhill, into electrical energy and storing it into battery. The problem on how to distribute braking forces of front wheel and rear wheel for electric vehicles with four-wheel drive was more complex than that for electric vehicles with front-wheel drive or rear-wheel drive. In this work, the frictional braking forces distribution curve of front wheel and rear wheel is determined by optimizing the braking force distribution curve of hydraulic proportional-adjustable valve, and then the safety brake range is obtained correspondingly. A new braking force distribution strategy based on regenerative braking strength continuity is proposed to solve the braking force distribution problem for electric vehicles with four-wheel drive. Highway fuel economy test(HWFET) driving condition is used to provide the speed signals, the braking force equations of front wheel and rear wheel are expressed with linear equations. The feasibility, effectiveness, and practicality of the new braking force distribution strategy based on regenerative braking strength continuity are verified by regenerative braking strength simulation curve and braking force distribution simulation curves of front wheel and rear wheel. The proposed strategy is simple in structure, easy to be implemented and worthy being spread.
文摘Currently, most efficient algorithms for force-closure analysis and dynamic force distribution utilize linear programming, but friction models are nonlinear. Substituting polyhedral cones for circular cones of Coulomb friction realizes the linearization of the frictional point contact constraint. So far, however, there is no approach to soft finger contact. This paper present such an approach. Then the foregoing algorithms can be extended to grasping with soft finger contact. Herein an optimal force distribution algorithm for soft multifingered grasps is developed with an illustrative example.
基金National Science and Technology Pillar Program, No.2012BAH48F01 Chinese Academy of Sciences Visiting Professorship for Senior International Scientists, No.2013T2Z0004+1 种基金 National Natural Science Foundation of China, No.41171165 No.41301204
文摘This study applies ArcGIS to analyze the spatiotemporal distribution of cultural sites in the Ill River Valley in northwestern China. It explores relationships between the sites＇ spatiotemporal evolutionary characteristics, human history, and the natural environment. The results indicate that the numbers and proportions of the sites, and the frequency of their oc- currence, exhibited an inverted V-shaped change trend during six historical periods. The ＂high in the east and low in the west＂ spatial distribution pattern of the first three periods shifted to the one the ＂high in the west and low in the east＂ during the latter three periods, demonstrating a change in the spatial center of gravity of human activities. The sites were mainly distributed on slopes of grades 1-5, with their proportions increasing from 75% during the Spring and Autumn Period （770 BC-476 BC）-Qin Dynasty （221 BC-207 BC） to 93.75% during the Qing Dynasty-Modern period. The concentrated distribution of site elevations shifted from grades 4-8 during the Spring and Autumn Period-Qin Dynasty, and the Western Han （206 BC-8）-Southern and Northern Dynasties （420-589）, to grades 1-4 during the latter three periods. The number of sites showed a shifting trend from high-elevation mountains and hills to low-elevation plains, and from high slopes to low slopes. In particular, the sites exhibited a special ＂moist＂ evolutionary pattern of migration from middle and upstream areas to downstream areas, as opposed to the migration pattern of sites located in typical arid areas. The study also considered factors influencing the distribution and spatiotemporal evolution of cultural sites, notably, human factors and natural factors.
