The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to researc...The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to research the theory of sediment movement. However, there is not a measuring and computing method to measure the bed shear stress under a complicated dynamic effect like wave and current. This paper describes the measurement and test research on the bed shear stress in a long launder of direct current by the new instrument named thermal shearometer based on micro-nanotechnology. As shown by the research results, the thermal shearometer has a high response frequency and strong stability. The measured results can reflect the basic change of the bed shear stress under wave and wave-current effect, and confirm that the method of measuring bed shear stress under wave-current effect with thermal shearometer is feasible. Meanwhile, a preliminary method to compute the shear stress compounded by wave-current is put forward according to the tested and measured results, and then a reference for further study on the basic theory of sediment movement under a complicated dynamic effect is provided.展开更多
This paper examines the results of the distributed generation penetration in large-scale medium-voltage power distribution networks. The network examined as a study case consists of twenty one lines fed by three power...This paper examines the results of the distributed generation penetration in large-scale medium-voltage power distribution networks. The network examined as a study case consists of twenty one lines fed by three power substations. The injected power comes mainly from photovoltaic units. Specifically, the influences of distributed generation on the network branch currents, losses and voltage profile as well as on the short-circuit level at the medium voltage busbars of the infeeding substations are examined according to international and national standards. The arising problems are explored and technical solutions are proposed. This paper is a pilot application as general conclusions concerning the extended distributed generation penetration in real power distribution networks are set out.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.51309158)funds from the National Key Scientific Instrument and Equipment Development Project(Grant No.2013YQ04091108)Important and Large Scientific and Technical Project of the Ministry of Communications(Grant No.201132874640)
文摘The movement of sediment in estuary and on coast is directly restricted by the bed shear stress. Therefore, the research on the basic problem of sediment movement by the bed shear stress is an important way to research the theory of sediment movement. However, there is not a measuring and computing method to measure the bed shear stress under a complicated dynamic effect like wave and current. This paper describes the measurement and test research on the bed shear stress in a long launder of direct current by the new instrument named thermal shearometer based on micro-nanotechnology. As shown by the research results, the thermal shearometer has a high response frequency and strong stability. The measured results can reflect the basic change of the bed shear stress under wave and wave-current effect, and confirm that the method of measuring bed shear stress under wave-current effect with thermal shearometer is feasible. Meanwhile, a preliminary method to compute the shear stress compounded by wave-current is put forward according to the tested and measured results, and then a reference for further study on the basic theory of sediment movement under a complicated dynamic effect is provided.
文摘This paper examines the results of the distributed generation penetration in large-scale medium-voltage power distribution networks. The network examined as a study case consists of twenty one lines fed by three power substations. The injected power comes mainly from photovoltaic units. Specifically, the influences of distributed generation on the network branch currents, losses and voltage profile as well as on the short-circuit level at the medium voltage busbars of the infeeding substations are examined according to international and national standards. The arising problems are explored and technical solutions are proposed. This paper is a pilot application as general conclusions concerning the extended distributed generation penetration in real power distribution networks are set out.
