The movement pattern of ellipsoidal nanoparticles confined between copper surfaces was examined using a theoretical model and molecular dynamics simulation.Initially,we developed a theoretical model of movement patter...The movement pattern of ellipsoidal nanoparticles confined between copper surfaces was examined using a theoretical model and molecular dynamics simulation.Initially,we developed a theoretical model of movement patterns for hard ellipsoidal nanoparticles.Subsequently,the simulation indicated that there are critical values for increasing the axial ratio,driving velocity of the contact surface,and lowering normal loads(i.e.,0.83,15 m/s,and 100 nN under the respective conditions),which in turn change the movement pattern of nanoparticles from sliding to rolling.Based on the comparison between the ratio of arm of force(e/h)and coefficient of friction(μ),the theoretical model was in good agreement with the simulations and accurately predicted the movement pattern of ellipsoidal nanoparticles.The sliding of the ellipsoidal nanoparticles led to severe surface damage.However,rolling separated the contact surfaces and thereby reduced friction and wear.展开更多
As a typical rhythmic movement, human being＇s rhythmic gait movement can be generated by a central pattern generator （CPG） located in a spinal cord by self- oscillation. Some kinds of gait movements are caused by g...As a typical rhythmic movement, human being＇s rhythmic gait movement can be generated by a central pattern generator （CPG） located in a spinal cord by self- oscillation. Some kinds of gait movements are caused by gait frequency and amplitude variances. As an important property of human being＇s motion vision, the attention selection mechanism plays a vital part in the regulation of gait movement. In this paper, the CPG model is amended under the condition of attention selection on the theoretical basis of Matsuoka neural oscillators. Regulation of attention selection signal for the CPG model parameters and structure is studied, which consequentially causes the frequency and amplitude changes of gait movement output. Further, the control strategy of the CPG model gait movement under the condition of attention selection is discussed, showing that the attention selection model can regulate the output model of CPG gait movement in three different ways. The realization of regulation on the gait movement frequency and amplitude shows a variety of regulation on the CPG gait movement made by attention selection and enriches the controllability of CPG gait movement, which demonstrates potential influence in engineering applications.展开更多
Population movement is an important phenomenon in China in recent years. Its mechanism is: (1) thrust of more people and less land in the eastern region of China; (2) attraction of dual economy in the western region o...Population movement is an important phenomenon in China in recent years. Its mechanism is: (1) thrust of more people and less land in the eastern region of China; (2) attraction of dual economy in the western region of China; (3) national policy on preferential wages and grains for the western region. Population movement has an important effect on the change of regional division pattern in China: by the medium of the moving people, there forms another regional division pattern, i.e. rural industry system based on rural town industry; (2) there forms another profit mechanism compensated from the western region to the eastern region. It not only wins more profit in the eastern region, but also changes dual economy in the western region. Therefore, We should make choice of a comprehensible and encouraging attitude on population movement; a special government organization for general survey of the moving people should be set up at once.展开更多
基金The authors acknowledge the financial support from the National Natural Science Fundation of China(NSFC)(51905433)the National Key R&D Program of China(No.2018YFB0703800)the Fundamental Research Funds for the Central Universities(No.3102019TS0405).
文摘The movement pattern of ellipsoidal nanoparticles confined between copper surfaces was examined using a theoretical model and molecular dynamics simulation.Initially,we developed a theoretical model of movement patterns for hard ellipsoidal nanoparticles.Subsequently,the simulation indicated that there are critical values for increasing the axial ratio,driving velocity of the contact surface,and lowering normal loads(i.e.,0.83,15 m/s,and 100 nN under the respective conditions),which in turn change the movement pattern of nanoparticles from sliding to rolling.Based on the comparison between the ratio of arm of force(e/h)and coefficient of friction(μ),the theoretical model was in good agreement with the simulations and accurately predicted the movement pattern of ellipsoidal nanoparticles.The sliding of the ellipsoidal nanoparticles led to severe surface damage.However,rolling separated the contact surfaces and thereby reduced friction and wear.
基金supported by the National Natural Science Foundation of China(Nos.11232005 and11472104)the Doctoral Fund of Ministry of Education of China(No.20120074110020)
文摘As a typical rhythmic movement, human being＇s rhythmic gait movement can be generated by a central pattern generator （CPG） located in a spinal cord by self- oscillation. Some kinds of gait movements are caused by gait frequency and amplitude variances. As an important property of human being＇s motion vision, the attention selection mechanism plays a vital part in the regulation of gait movement. In this paper, the CPG model is amended under the condition of attention selection on the theoretical basis of Matsuoka neural oscillators. Regulation of attention selection signal for the CPG model parameters and structure is studied, which consequentially causes the frequency and amplitude changes of gait movement output. Further, the control strategy of the CPG model gait movement under the condition of attention selection is discussed, showing that the attention selection model can regulate the output model of CPG gait movement in three different ways. The realization of regulation on the gait movement frequency and amplitude shows a variety of regulation on the CPG gait movement made by attention selection and enriches the controllability of CPG gait movement, which demonstrates potential influence in engineering applications.
文摘Population movement is an important phenomenon in China in recent years. Its mechanism is: (1) thrust of more people and less land in the eastern region of China; (2) attraction of dual economy in the western region of China; (3) national policy on preferential wages and grains for the western region. Population movement has an important effect on the change of regional division pattern in China: by the medium of the moving people, there forms another regional division pattern, i.e. rural industry system based on rural town industry; (2) there forms another profit mechanism compensated from the western region to the eastern region. It not only wins more profit in the eastern region, but also changes dual economy in the western region. Therefore, We should make choice of a comprehensible and encouraging attitude on population movement; a special government organization for general survey of the moving people should be set up at once.
