Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- a...Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- and three-dimensional moving boundary problem, which combines the adaptive multi-grid finite volume method and the methods of immersed boundary and volume of fluid, it is found that due to the interactions of vortices in the wakes, without proper control, a fish school swim with a given flap- ping rule can not keep the fixed shape of a queue. In order to understand the secret of fish swimming, a new feedback con- trol strategy of fish motion is proposed for the first time, i,e., the locomotion speed is adjusted by the flapping frequency of the caudal, and the direction of swimming is controlled by the swinging of the head of a fish. Results show that with this feedback control strategy, a fish school can keep the good order of a queue in cruising, turning or swimming around circles. This new control strategy, which separates the speed control and direction control, is important in the construction of biomimetic robot fish, with which it greatly simplifies the control devices of a biomimetic robot fish.展开更多
The DSC(direct self control) of speed regulation technology was applied to drive a motor running at a certain overloading ratio in intermittent working conditions.To control motor temperatures rising effectively,a fin...The DSC(direct self control) of speed regulation technology was applied to drive a motor running at a certain overloading ratio in intermittent working conditions.To control motor temperatures rising effectively,a finite element method with an iterative approach was applied to simulate real working conditions and analyze the temperature rising of the inner part of the motor.Application of DSC speed regulation realizes the invariable torque output quickly and avoids the peak current at the start state in favor of the motor temperature decreasing.Based on an analysis with the finite limit method,some effective measures were taken to improve the ability of the motor to expel heat.The overload ability of the motor was improved and the stable motor temperature rising was obtained,fulfilling the demands of electrical screw presses.展开更多
为有效抑制高压直流输电系统在不同故障程度下的换相失败,提出了一种基于自适应电压限值的改进低压限流控制器(voltage dependent current order limiter,VDCOL)设计方案。首先,详细分析了包含传统VDCOL的直流输电系统在换相失败及恢复...为有效抑制高压直流输电系统在不同故障程度下的换相失败,提出了一种基于自适应电压限值的改进低压限流控制器(voltage dependent current order limiter,VDCOL)设计方案。首先,详细分析了包含传统VDCOL的直流输电系统在换相失败及恢复期间的运行特性,并提出VDCOL曲线在不同时间段下应具备的动态性能。然后,引入直流电流这一反映故障特性的时变电气量优化传统VDCOL的直流电压上下限值,从而在不同时间段自适应改变电流指令启动电压阈值与电压-电流指令变化趋势,以满足输电系统换相失败及恢复期间的有功与无功需求。同时考虑到VDCOL电压上下限值的过度变化会恶化系统运行特性,对其范围的设置进行了解析和合理选取。最后,在PSCAD/EMTDC中对所提方法进行仿真测试。结果表明,所提出的改进控制策略能在一定程度上抑制直流输电系统的连续换相失败,同时有效地改善换相失败各阶段直流输电系统的运行特性。展开更多
In this paper,an application of a nonlinear predictive controller based on a self recurrent wavelet network (SRWN) model for a direct internal reforming solid oxide fuel cell (DIR-SOFC) is presented. As operating temp...In this paper,an application of a nonlinear predictive controller based on a self recurrent wavelet network (SRWN) model for a direct internal reforming solid oxide fuel cell (DIR-SOFC) is presented. As operating temperature and fuel utilization are two important parameters,the SOFC is identified using an SRWN with inlet fuel flow rate,inlet air flow rate and current as inputs,and temperature and fuel utilization as outputs. To improve the operating performance of the DIR-SOFC and guarantee proper operating conditions,the nonlinear predictive control is implemented using the off-line trained and on-line modified SRWN model,to manipulate the inlet flow rates to keep the temperature and the fuel utilization at desired levels. Simulation results show satisfactory predictive accuracy of the SRWN model,and demonstrate the excellence of the SRWN-based predictive controller for the DIR-SOFC.展开更多
基金supported by the National Natural Science Foundation of China(10172095 and 10672183)
文摘Numerical simulation and control of self- propelled swimming of two- and three-dimensional biomimetic fish school in a viscous flow are investigated. With a parallel computational fluid dynamics package for the two- and three-dimensional moving boundary problem, which combines the adaptive multi-grid finite volume method and the methods of immersed boundary and volume of fluid, it is found that due to the interactions of vortices in the wakes, without proper control, a fish school swim with a given flap- ping rule can not keep the fixed shape of a queue. In order to understand the secret of fish swimming, a new feedback con- trol strategy of fish motion is proposed for the first time, i,e., the locomotion speed is adjusted by the flapping frequency of the caudal, and the direction of swimming is controlled by the swinging of the head of a fish. Results show that with this feedback control strategy, a fish school can keep the good order of a queue in cruising, turning or swimming around circles. This new control strategy, which separates the speed control and direction control, is important in the construction of biomimetic robot fish, with which it greatly simplifies the control devices of a biomimetic robot fish.
基金the Natural Science Foundation of Hubei Province (No.2004AA101E04)
文摘The DSC(direct self control) of speed regulation technology was applied to drive a motor running at a certain overloading ratio in intermittent working conditions.To control motor temperatures rising effectively,a finite element method with an iterative approach was applied to simulate real working conditions and analyze the temperature rising of the inner part of the motor.Application of DSC speed regulation realizes the invariable torque output quickly and avoids the peak current at the start state in favor of the motor temperature decreasing.Based on an analysis with the finite limit method,some effective measures were taken to improve the ability of the motor to expel heat.The overload ability of the motor was improved and the stable motor temperature rising was obtained,fulfilling the demands of electrical screw presses.
文摘为有效抑制高压直流输电系统在不同故障程度下的换相失败,提出了一种基于自适应电压限值的改进低压限流控制器(voltage dependent current order limiter,VDCOL)设计方案。首先,详细分析了包含传统VDCOL的直流输电系统在换相失败及恢复期间的运行特性,并提出VDCOL曲线在不同时间段下应具备的动态性能。然后,引入直流电流这一反映故障特性的时变电气量优化传统VDCOL的直流电压上下限值,从而在不同时间段自适应改变电流指令启动电压阈值与电压-电流指令变化趋势,以满足输电系统换相失败及恢复期间的有功与无功需求。同时考虑到VDCOL电压上下限值的过度变化会恶化系统运行特性,对其范围的设置进行了解析和合理选取。最后,在PSCAD/EMTDC中对所提方法进行仿真测试。结果表明,所提出的改进控制策略能在一定程度上抑制直流输电系统的连续换相失败,同时有效地改善换相失败各阶段直流输电系统的运行特性。
基金supported by the National High-Tech Research and Devel-opment Program (863) of China (No. 2006AA05Z148)the Shanghai Municipal Natural Science Foundation, China (No. 08ZR1409800)
文摘In this paper,an application of a nonlinear predictive controller based on a self recurrent wavelet network (SRWN) model for a direct internal reforming solid oxide fuel cell (DIR-SOFC) is presented. As operating temperature and fuel utilization are two important parameters,the SOFC is identified using an SRWN with inlet fuel flow rate,inlet air flow rate and current as inputs,and temperature and fuel utilization as outputs. To improve the operating performance of the DIR-SOFC and guarantee proper operating conditions,the nonlinear predictive control is implemented using the off-line trained and on-line modified SRWN model,to manipulate the inlet flow rates to keep the temperature and the fuel utilization at desired levels. Simulation results show satisfactory predictive accuracy of the SRWN model,and demonstrate the excellence of the SRWN-based predictive controller for the DIR-SOFC.
