The harsh operating environment and complex operating conditions of the mine electric locomotive affect the control performance of the locomotive traction motor.In order to improve the speed control performance of ele...The harsh operating environment and complex operating conditions of the mine electric locomotive affect the control performance of the locomotive traction motor.In order to improve the speed control performance of electric locomotive traction motors,a dynamic fractional-order sliding mode control(DFOSMC)algorithm considering uncertain factors was proposed.A load torque sliding mode observer was designed for the complex load disturbance of the traction motor,and its observations were integrated into the DFOSMC controller to overcome the influence of load disturbance.Finally,the stability of the designed controller was proved by Lyapunov's theorem.Besides,the control performance of DFOSMC controller was compared with integer-order sliding mode controller and fractional-order sliding mode controller through simulation experiments.Compared with integer-order sliding mode and fractional-order sliding mode controllers,the dynamic and static performance of the DFOSMC controller with load observation is better,and it has stronger anti-interference ability.The DFOSMC controller effectively improves the control performance of the traction motor of the mining locomotive.展开更多
To complete the contact fatigue reliability analysis of spur gear under elastohydrodynamic lubrication(EHL) efficiently and accurately, an intelligent method is proposed. Oil film pressure is approximated using quadra...To complete the contact fatigue reliability analysis of spur gear under elastohydrodynamic lubrication(EHL) efficiently and accurately, an intelligent method is proposed. Oil film pressure is approximated using quadratic polynomial with intercrossing term and then mapped into the Hertz contact zone. Considering the randomness of the EHL, material properties and fatigue strength correction factors, the probabilistic reliability analysis model is established using artificial neural network(ANN). Genetic algorithm(GA) is employed to search the minimum reliability index and the design point by introducing an adjusting factor in penalty function. Reliability sensitivity analysis is completed based on the advanced first order second moment(AFOSM). Numerical example shows that the established probabilistic reliability analysis model could correctly reflect the effect of EHL on contact fatigue of spur gear, and the proposed intelligent method has an excellent global search capability as well as a highly efficient computing performance compared with the traditional Monte Carlo method(MCM).展开更多
There is a growing interest in propellers for transport aircraft as well as regional airliners from the viewpoint of energy saving. An important consideration for utilizing a propeller propulsion system on aircraft is...There is a growing interest in propellers for transport aircraft as well as regional airliners from the viewpoint of energy saving. An important consideration for utilizing a propeller propulsion system on aircraft is the aerodynamic interaction between the propeller slipstream and other aerodynamic surfaces. It is therefore necessary to use a simplified but relatively accurate tool for propeller modeling, with the widely used actuator disk model. The advantage of this model is that it is easy to use and inex- pensive in terms of computation time required. In addition, it also produces acceptable results. In this study, a new regionalized actuator disk model was utilized in the analysis of propeller slipstream interference effects on a real four-propeller aircraft. The results are compared with the cases of inactive actuator disks, which shows that the propeller slipstream causes an increase in the lift and drag coefficients. An evident yawing effect caused by the rotating slipstream was noticed, which should be taken into account in the design phase. The regionalized actuator disk model is evaluated as a fast and relatively accurate model for propeller preliminary design.展开更多
基金National Natural Science Foundation of China(No.51867012)。
文摘The harsh operating environment and complex operating conditions of the mine electric locomotive affect the control performance of the locomotive traction motor.In order to improve the speed control performance of electric locomotive traction motors,a dynamic fractional-order sliding mode control(DFOSMC)algorithm considering uncertain factors was proposed.A load torque sliding mode observer was designed for the complex load disturbance of the traction motor,and its observations were integrated into the DFOSMC controller to overcome the influence of load disturbance.Finally,the stability of the designed controller was proved by Lyapunov's theorem.Besides,the control performance of DFOSMC controller was compared with integer-order sliding mode controller and fractional-order sliding mode controller through simulation experiments.Compared with integer-order sliding mode and fractional-order sliding mode controllers,the dynamic and static performance of the DFOSMC controller with load observation is better,and it has stronger anti-interference ability.The DFOSMC controller effectively improves the control performance of the traction motor of the mining locomotive.
基金Project(CX2014B060) supported by Hunan Provincial Innovation for Postgraduate,ChinaProject(8130208) supported by General Armament Pre-research Foundation
文摘To complete the contact fatigue reliability analysis of spur gear under elastohydrodynamic lubrication(EHL) efficiently and accurately, an intelligent method is proposed. Oil film pressure is approximated using quadratic polynomial with intercrossing term and then mapped into the Hertz contact zone. Considering the randomness of the EHL, material properties and fatigue strength correction factors, the probabilistic reliability analysis model is established using artificial neural network(ANN). Genetic algorithm(GA) is employed to search the minimum reliability index and the design point by introducing an adjusting factor in penalty function. Reliability sensitivity analysis is completed based on the advanced first order second moment(AFOSM). Numerical example shows that the established probabilistic reliability analysis model could correctly reflect the effect of EHL on contact fatigue of spur gear, and the proposed intelligent method has an excellent global search capability as well as a highly efficient computing performance compared with the traditional Monte Carlo method(MCM).
基金supported by the Key Projects in the National Science&Technology Pillar Program during the Eleventh Five-Year Plan Period(Grant No.2009BAG12A01)
文摘There is a growing interest in propellers for transport aircraft as well as regional airliners from the viewpoint of energy saving. An important consideration for utilizing a propeller propulsion system on aircraft is the aerodynamic interaction between the propeller slipstream and other aerodynamic surfaces. It is therefore necessary to use a simplified but relatively accurate tool for propeller modeling, with the widely used actuator disk model. The advantage of this model is that it is easy to use and inex- pensive in terms of computation time required. In addition, it also produces acceptable results. In this study, a new regionalized actuator disk model was utilized in the analysis of propeller slipstream interference effects on a real four-propeller aircraft. The results are compared with the cases of inactive actuator disks, which shows that the propeller slipstream causes an increase in the lift and drag coefficients. An evident yawing effect caused by the rotating slipstream was noticed, which should be taken into account in the design phase. The regionalized actuator disk model is evaluated as a fast and relatively accurate model for propeller preliminary design.
