The grading ring (GR) can adjust the potential distribution along the composite insulator and reduce the electric field (E-field) strengths near its end fittings. However, little research has been conducted about the effects of GR on the insulation performance of composite insulators under icing condition. Therefore, the ac icing flashover performance of two kinds of 220 kV composite insulators under different GR arrangement patterns are tested in the artificial climate chamber. Combining with the numerical simulation, the effects are analyzed. The results indicate that when GR is installed at the high voltage (HV) end, the E-field strength close to the end fitting and the icing uniformity on the whole insulators are both improved. These cause the effect of icing degree on the icing flashover voltage to be larger than that without GR at the HV end. When GR is installed at the grounded end, the perpendicular icicles on the GR will impact the flashover arc path, which causes the icing flashover voltages to be lower than that without GR at the grounded end. When different GRs are only installed at the HV end, the characteristic exponents b (characterizing the influence of freezing water conductivity on icing flashover voltage) are all larger than that without GR. Moreover, the value of b increases with the decrease of GR's diameter and with the raise of GR's height. But b changes slightly when there are variations in GR's pipe diameter and structure. The research can provide reference for the application of GR for 220 kV composite insulators in icing regions.Index Terms -Grading ring, composite insulator, ice accretion, icing flashover voltage, potential distribution.

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In this work, a method to eliminate ice on wind turbine blade by using carbon fiber composites was put forward. To prove that this idea is feasible, a carbon fiber composite panel with its ends soaked by the conductive silver paste was fabricated and surface temperature of it at three levels of voltages was measured. The surface temperature of the composite panel increased significantly and finally retained a constant, which shows that the carbon fiber composites can be used to eliminate ice when the glass fabric composite blades are covered by the carbon fiber composites.

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Against the problem of water-land intermodal transport logistics in area of Yangtze River, based on the method of bi-level programming, a layout optimization model of the area under the condition of flow of goods in dual direction is built up. The model involves optimized selection of ports as the intermodal transport hubs and determination of throughout of ports after construction from the point view of logistic planning department and optimized selection of water-land intermodal transport routes and determination of goods volume among the routes. The example reveals that the problem of layout optimization in Yangtze River basin under the condition of dual-direction goods flow can be modeled by bi-level programming, and the model can be solved by two kinds of algorithms including two-phrase one and adding objective functions.