The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Na...The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Navier-Stokes equations using RNG k-ε turbulence closure. The volume of fluid（VOF） method is used to locate the free surface. The 3D virtual model is created by Computer Aided Industrial Design（CAID） software, Rhinoceros. Firstly, a specific posture of swimming is studied. The simulation results are in good agreement with the data from mannequin towing experiments. The effects of a swimmer＇s arms and legs positions on swimming performance are then studied. Finally, it is demonstrated that the present method is capable of simulating gliding near the free surface.展开更多
Two simulation crash tests were carried out in Tianjin and Shanghai respectively with a domestically developed setup and a imported system. Both are for their first time in China. Through more than 3 year’s efforts a...Two simulation crash tests were carried out in Tianjin and Shanghai respectively with a domestically developed setup and a imported system. Both are for their first time in China. Through more than 3 year’s efforts and with the assistance of UNDP (United Nations Development Programme) Beijing, CATARC has established its simulation crash test setup for auto components. This setup is the first such kind of equipment developed in China, and it consists of catapult, energy absorption system, measurement system, high-speed camera, film analysis system, TNO-10 Dummy and HybridⅡ Dummy. The setup can be used to carry out展开更多
Passive torque servo system （PTSS） simulates aerodynamic load and exerts the load on actuation system, but PTSS endures position coupling disturbance from active motion of actuation system, and this inherent disturb...Passive torque servo system （PTSS） simulates aerodynamic load and exerts the load on actuation system, but PTSS endures position coupling disturbance from active motion of actuation system, and this inherent disturbance is called extra torque. The most important issue for PTSS controller design is how to eliminate the influence of extra torque. Using backstepping technique, adaptive fuzzy torque control （AFTC） algorithm is proposed for PTSS in this paper, which reflects the essential characteristics of PTSS and guarantees transient tracking performance as well as final tracking accuracy. Takagi-Sugeno （T-S） fuzzy logic system is utilized to compensate parametric uncertainties and unstructured uncertainties. The output velocity of actuator identified model is introduced into AFTC aiming to eliminate extra torque. The closed-loop stability is studied using small gain theorem and the control system is proved to be semiglobally uniformly ultimately bounded. The proposed AFTC algorithm is applied to an electric load simulator （ELS）, and the comparative experimental results indicate that AFTC controller is effective for PTSS.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities of China
文摘The aim of this work is to build a 3D numerical model to study the characteristics of passive drag on competitive swimmers taking into account the impact of the free surface. This model solves the 3D incompressible Navier-Stokes equations using RNG k-ε turbulence closure. The volume of fluid（VOF） method is used to locate the free surface. The 3D virtual model is created by Computer Aided Industrial Design（CAID） software, Rhinoceros. Firstly, a specific posture of swimming is studied. The simulation results are in good agreement with the data from mannequin towing experiments. The effects of a swimmer＇s arms and legs positions on swimming performance are then studied. Finally, it is demonstrated that the present method is capable of simulating gliding near the free surface.
文摘Two simulation crash tests were carried out in Tianjin and Shanghai respectively with a domestically developed setup and a imported system. Both are for their first time in China. Through more than 3 year’s efforts and with the assistance of UNDP (United Nations Development Programme) Beijing, CATARC has established its simulation crash test setup for auto components. This setup is the first such kind of equipment developed in China, and it consists of catapult, energy absorption system, measurement system, high-speed camera, film analysis system, TNO-10 Dummy and HybridⅡ Dummy. The setup can be used to carry out
基金National High-tech Research and Development Program of China (2009AA04Z412)"111" ProjectBUAA Fund of Graduate Education and Development
文摘Passive torque servo system （PTSS） simulates aerodynamic load and exerts the load on actuation system, but PTSS endures position coupling disturbance from active motion of actuation system, and this inherent disturbance is called extra torque. The most important issue for PTSS controller design is how to eliminate the influence of extra torque. Using backstepping technique, adaptive fuzzy torque control （AFTC） algorithm is proposed for PTSS in this paper, which reflects the essential characteristics of PTSS and guarantees transient tracking performance as well as final tracking accuracy. Takagi-Sugeno （T-S） fuzzy logic system is utilized to compensate parametric uncertainties and unstructured uncertainties. The output velocity of actuator identified model is introduced into AFTC aiming to eliminate extra torque. The closed-loop stability is studied using small gain theorem and the control system is proved to be semiglobally uniformly ultimately bounded. The proposed AFTC algorithm is applied to an electric load simulator （ELS）, and the comparative experimental results indicate that AFTC controller is effective for PTSS.
