综合电力系统(Integrated Power System,IPS)作为未来舰船发展的重要组成部分,代表着先进的集成优化电力系统发展方向。为深入研究IPS中配电网保护策略,叙述了近年来IPS国内外发展情况,较全面的分析了IPS中配电网络的特点,结合几种常用...综合电力系统(Integrated Power System,IPS)作为未来舰船发展的重要组成部分,代表着先进的集成优化电力系统发展方向。为深入研究IPS中配电网保护策略,叙述了近年来IPS国内外发展情况,较全面的分析了IPS中配电网络的特点,结合几种常用母线继电保护措施在IPS中的应用情况,指出了保护实现的难点和关键;综述了IPS交流网络中单相接地故障的探测与诊断方法和陆地中性点不接地系统中单相接地故障的研究方法。最后,指出IPS配电网络的未来发展方向,讨论了IPS中压直流配电网的相应保护策略发展的方向。展开更多
A numerical study on flow control of ship airwake during shipboard landing is carried out to address the effect of flow control devices on helicopter rotor airload. The in-house Reynolds Averaged Navier-Stokes(RANS) b...A numerical study on flow control of ship airwake during shipboard landing is carried out to address the effect of flow control devices on helicopter rotor airload. The in-house Reynolds Averaged Navier-Stokes(RANS) based solver Rotorcraft AeroDynamics and Aeroacoustics Solver(RADAS), with combination of momentum source approach is employed to conduct the helicopter shipboard landing simulation. The control effects of three aerodynamic modifications of ship superstructure, i.e. ramp, notch and flap, in different Wind-Over-Deck(WOD) conditions are discussed.From the steady simulation results, the effect of spatial variation of ship airwake on rotor airloads is concluded. The aerodynamic modifications reduce the strength of shedding vortex and increase rotor normal force through delaying and relieving flow separation, and therefore are beneficial to alleviate the limitation of control inputs. By contrast, the perturbation of unsteady ship airwake can cause the serious oscillation of rotor forces during shipboard landing. The unsteady simulations show that the turbulence intensity of ship airwake and oscillatory rotor airloading, represented by Root-Mean-Square(RMS) loading, can be remarkably reduced by the ramp and notch modifications, while the flap modification has adverse effect. It means that flow control devices have large potential benefits to alleviate the pilot's workload and improve the shipboard landing safety, but they should be well designed to avoid the introduction of more vortex, which leads to increase in disturbance of flow field.展开更多
Shipboard cranes are extensively utilized in numerous fields such as cargo transferring and offshore engineering.The control of shipboard cranes,especially the antiswing control of payloads,has attracted much research...Shipboard cranes are extensively utilized in numerous fields such as cargo transferring and offshore engineering.The control of shipboard cranes,especially the antiswing control of payloads,has attracted much research attention due to their typical underactuation characteristics and complicated dynamics.Through comparisons of the traditional land-fixed cranes,a brief review on modeling and dynamics analysis is presented to illustrate the tremendous challenges and difficulties in controller design for shipboard cranes.A comprehensive review and brief analysis of shipboard crane control strategies are further presented.Some future research directions are also put forward for reference.It is expected that the paper will be useful for improving existing control schemes and generating novel control approaches for shipboard crane systems.展开更多
文摘综合电力系统(Integrated Power System,IPS)作为未来舰船发展的重要组成部分,代表着先进的集成优化电力系统发展方向。为深入研究IPS中配电网保护策略,叙述了近年来IPS国内外发展情况,较全面的分析了IPS中配电网络的特点,结合几种常用母线继电保护措施在IPS中的应用情况,指出了保护实现的难点和关键;综述了IPS交流网络中单相接地故障的探测与诊断方法和陆地中性点不接地系统中单相接地故障的研究方法。最后,指出IPS配电网络的未来发展方向,讨论了IPS中压直流配电网的相应保护策略发展的方向。
基金supported by the Fundamental Research Funds for the Central Universities (No. NS2018007)
文摘A numerical study on flow control of ship airwake during shipboard landing is carried out to address the effect of flow control devices on helicopter rotor airload. The in-house Reynolds Averaged Navier-Stokes(RANS) based solver Rotorcraft AeroDynamics and Aeroacoustics Solver(RADAS), with combination of momentum source approach is employed to conduct the helicopter shipboard landing simulation. The control effects of three aerodynamic modifications of ship superstructure, i.e. ramp, notch and flap, in different Wind-Over-Deck(WOD) conditions are discussed.From the steady simulation results, the effect of spatial variation of ship airwake on rotor airloads is concluded. The aerodynamic modifications reduce the strength of shedding vortex and increase rotor normal force through delaying and relieving flow separation, and therefore are beneficial to alleviate the limitation of control inputs. By contrast, the perturbation of unsteady ship airwake can cause the serious oscillation of rotor forces during shipboard landing. The unsteady simulations show that the turbulence intensity of ship airwake and oscillatory rotor airloading, represented by Root-Mean-Square(RMS) loading, can be remarkably reduced by the ramp and notch modifications, while the flap modification has adverse effect. It means that flow control devices have large potential benefits to alleviate the pilot's workload and improve the shipboard landing safety, but they should be well designed to avoid the introduction of more vortex, which leads to increase in disturbance of flow field.
基金supported in part by the National Natural Science Foundation of China(51939001,61751202,61803064,61976033,U1813203)the Fundamental Research Funds for the Central Universities(3132019124,3132019126,3132019140)+2 种基金the China Scholarship Council(201903210010)the Natural Science Foundation of Liaoning Province(20170540093,20180550082)the Science and Technology Innovation Funds of Dalian(2018J11CY022)
文摘Shipboard cranes are extensively utilized in numerous fields such as cargo transferring and offshore engineering.The control of shipboard cranes,especially the antiswing control of payloads,has attracted much research attention due to their typical underactuation characteristics and complicated dynamics.Through comparisons of the traditional land-fixed cranes,a brief review on modeling and dynamics analysis is presented to illustrate the tremendous challenges and difficulties in controller design for shipboard cranes.A comprehensive review and brief analysis of shipboard crane control strategies are further presented.Some future research directions are also put forward for reference.It is expected that the paper will be useful for improving existing control schemes and generating novel control approaches for shipboard crane systems.
