The quantum electronic transport through a precessing magnetic spin coupled to noncollinearly polarized ferromagnetic leads （F-MS-F） has been studied in this paper. The nonequilibrium Green function approach is used...The quantum electronic transport through a precessing magnetic spin coupled to noncollinearly polarized ferromagnetic leads （F-MS-F） has been studied in this paper. The nonequilibrium Green function approach is used to calculate local density of states （LDOS） and current in the presence of external bias. The characters of LDOS and the electronic current are obtained. The tunneling current is investigated for different precessing angle and different configurations of the magnetization of the leads. The investigation revea/s that when the precessing angle takes θ 〈 π /2 and negative bias is applied, the resonant tunneling current appears, otherwise, it appears when positive bias is applied. When the leads are totally polarized and the precessing angel takes O, the tunneling current changes with the configuration of two leads; and it becomes zero when the two leads are antiparallel.展开更多
Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a ...Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a non-linear dynamics model. An adaptive tracking controller for the kinematic model of a nonhotonomic mobile robot with unknown parameters is also proposed. Using control Lyapunov function （CLF）, the controller＇s global asymptotic stability has been proven. The adaptive trajectory tracking controller decreases the disturbance in the course of tracking control and enhances the real-time control characteristics. The simulation result indicated that the wheeled mobile robot tracking can be effectively controlled.展开更多
Organic spintronics refers to control spin dependent transport through organic materials.In the last two decades,extraordinary development has been achieved for organic-spintronics.A series of theoretical and experime...Organic spintronics refers to control spin dependent transport through organic materials.In the last two decades,extraordinary development has been achieved for organic-spintronics.A series of theoretical and experimental studies have been done to reveal the mechanisms of spin dependent transport properties.The theoretical analysis is based on the non-equilibrium Green's function formalism provides a mathematical framework for solving the transmission coefficients in the Landauer formula from atomistic first principles without any phenomenological parameters.In this article,we provide a brief theoretical review on organic spintronics devices and device physics therein.展开更多
基金Supported by National Natural Science Foundation of China under Grant No. 10674092Shanghai Leading Academic Disciplines Project under Grant No. S30105
文摘The quantum electronic transport through a precessing magnetic spin coupled to noncollinearly polarized ferromagnetic leads （F-MS-F） has been studied in this paper. The nonequilibrium Green function approach is used to calculate local density of states （LDOS） and current in the presence of external bias. The characters of LDOS and the electronic current are obtained. The tunneling current is investigated for different precessing angle and different configurations of the magnetization of the leads. The investigation revea/s that when the precessing angle takes θ 〈 π /2 and negative bias is applied, the resonant tunneling current appears, otherwise, it appears when positive bias is applied. When the leads are totally polarized and the precessing angel takes O, the tunneling current changes with the configuration of two leads; and it becomes zero when the two leads are antiparallel.
基金Supported by the National High Technology Research and Development Programme of China (No. 2006AA04Z245)the Program for Changjiang Scholars and Innovative Research Team in University ( No. IRT0423)the Fund for Foreign Scholars in University Research and Teaching Programs (No. B07018)
文摘Wheeled mobile robot is one of the well-known nonholonomic systems. A two-wheeled sell-balance robot is taken as the research objective. This paper carried out a detailed force analysis of the robot and established a non-linear dynamics model. An adaptive tracking controller for the kinematic model of a nonhotonomic mobile robot with unknown parameters is also proposed. Using control Lyapunov function （CLF）, the controller＇s global asymptotic stability has been proven. The adaptive trajectory tracking controller decreases the disturbance in the course of tracking control and enhances the real-time control characteristics. The simulation result indicated that the wheeled mobile robot tracking can be effectively controlled.
基金supported by the State Key Project of Fundamental Research of the Ministry of Science and Technology(Grant No. 2010CB934400)the National Natural Science Foundation of China (Grant Nos.11104338,10934099,and 51021061)+1 种基金the International Collaborative Research Programs between NSFC and EPSRC of the United Kingdom(Grant No.10911130234)between NSFC and ANR of France(Grant No.F040803)
文摘Organic spintronics refers to control spin dependent transport through organic materials.In the last two decades,extraordinary development has been achieved for organic-spintronics.A series of theoretical and experimental studies have been done to reveal the mechanisms of spin dependent transport properties.The theoretical analysis is based on the non-equilibrium Green's function formalism provides a mathematical framework for solving the transmission coefficients in the Landauer formula from atomistic first principles without any phenomenological parameters.In this article,we provide a brief theoretical review on organic spintronics devices and device physics therein.
