The thrust generation by electro-hydrodynamic （EHD） effect has been studied for a wire-cylinder arrangement under high DC voltage. Series of measurements have been conducted in order to determine the relationship be...The thrust generation by electro-hydrodynamic （EHD） effect has been studied for a wire-cylinder arrangement under high DC voltage. Series of measurements have been conducted in order to determine the relationship between generated thrust and corona discharge current, as well as its dependence on geometrical characteristics of the electrodes, e.g. electrode gap, wire and cylinder radii. The experimental investigation has shown a linear relationship between the generated thrust and the discharge current, while parametric analysis showed that increased electrode gap and emitter radius reduces the thrust. On the other hand, large gaps favor the thrust per unit power ratio.展开更多
Aiming at the major failure mode of prestressed concrete cylinder pipes (PCCP),namely the fracture of prestressed steel wires,the broken wire detection technology based on orthogonal electromagnetic principle is studi...Aiming at the major failure mode of prestressed concrete cylinder pipes (PCCP),namely the fracture of prestressed steel wires,the broken wire detection technology based on orthogonal electromagnetic principle is studied. The detection system model is established and optimized by using COMSOL finite element simulation software. Furthermore,the theoretical analysis of the wire-breaking effect is carried out. The influence of factors on broken wire signal characteristics such as edge effect,circumferential relative position of the detector and broken wires,excitation frequency and relative permeability of steel wires is analyzed,which provides a theoretical guidance for the field detection. The influence of the steel cylinder structure on the simulation results is analyzed,which provides a reference for the improvement of calculation efficiency. The corresponding detection system is designed and implemented. Concretely,a high-voltage and high-power sinusoidal signal coil drive scheme based on sinusoidal pulse width modulation technology and an intelligent power module is innovatively proposed and the corresponding protection circuit is designed. The broken wire signal could be effectively extracted through a lock-in amplifier. The experimental results show that this system can effectively identify the broken wires with low cost.展开更多
对带有线控制动系统(brake by wire,BBW)的车辆进行研究,提出了一种横摆稳定性优化控制策略.以二自由度单轨车辆模型为参考模型,利用比例-积分(proportionalintegral,PI)控制算法求出附加横摆力矩.由所计算出的车辆附加横摆力矩、方向...对带有线控制动系统(brake by wire,BBW)的车辆进行研究,提出了一种横摆稳定性优化控制策略.以二自由度单轨车辆模型为参考模型,利用比例-积分(proportionalintegral,PI)控制算法求出附加横摆力矩.由所计算出的车辆附加横摆力矩、方向盘转角来识别驾驶员转向意图和车辆实际行驶特性,通过广义逆法和数学归划法相结合的方法将附加横摆力矩分配到作用车轮上,由线控制动系统采用主缸定频调压法对各轮缸的目标液压力进行跟踪控制.硬件在环试验结果表明,该控制策略能够有效地保证车辆在高附和低附路面工况下的横摆稳定性.展开更多
文摘The thrust generation by electro-hydrodynamic （EHD） effect has been studied for a wire-cylinder arrangement under high DC voltage. Series of measurements have been conducted in order to determine the relationship between generated thrust and corona discharge current, as well as its dependence on geometrical characteristics of the electrodes, e.g. electrode gap, wire and cylinder radii. The experimental investigation has shown a linear relationship between the generated thrust and the discharge current, while parametric analysis showed that increased electrode gap and emitter radius reduces the thrust. On the other hand, large gaps favor the thrust per unit power ratio.
基金National Natural Science Foundation of China(No.61304244)
文摘Aiming at the major failure mode of prestressed concrete cylinder pipes (PCCP),namely the fracture of prestressed steel wires,the broken wire detection technology based on orthogonal electromagnetic principle is studied. The detection system model is established and optimized by using COMSOL finite element simulation software. Furthermore,the theoretical analysis of the wire-breaking effect is carried out. The influence of factors on broken wire signal characteristics such as edge effect,circumferential relative position of the detector and broken wires,excitation frequency and relative permeability of steel wires is analyzed,which provides a theoretical guidance for the field detection. The influence of the steel cylinder structure on the simulation results is analyzed,which provides a reference for the improvement of calculation efficiency. The corresponding detection system is designed and implemented. Concretely,a high-voltage and high-power sinusoidal signal coil drive scheme based on sinusoidal pulse width modulation technology and an intelligent power module is innovatively proposed and the corresponding protection circuit is designed. The broken wire signal could be effectively extracted through a lock-in amplifier. The experimental results show that this system can effectively identify the broken wires with low cost.
文摘对带有线控制动系统(brake by wire,BBW)的车辆进行研究,提出了一种横摆稳定性优化控制策略.以二自由度单轨车辆模型为参考模型,利用比例-积分(proportionalintegral,PI)控制算法求出附加横摆力矩.由所计算出的车辆附加横摆力矩、方向盘转角来识别驾驶员转向意图和车辆实际行驶特性,通过广义逆法和数学归划法相结合的方法将附加横摆力矩分配到作用车轮上,由线控制动系统采用主缸定频调压法对各轮缸的目标液压力进行跟踪控制.硬件在环试验结果表明,该控制策略能够有效地保证车辆在高附和低附路面工况下的横摆稳定性.
