270V high voltage DC power supply system with grid of light weight, uninterrupted power supply and a two power density higher characteristic, in recent years become a hot research topic in domestic and international air supply system.[ To ensure the high voltage DC bus power quality, for the safe operation of the aircraft is very important. Single phase aeronautical static inverter as a typical aircraft power system load, the input current ripple of the serious pollution of the high voltage DC power supply. Therefore, the harmonic pollution problem of how to control the high voltage DC power supply system has been increasingly concerned aviation power researchers.
Electrical contractor affects reliability and working life of switches and electrical equipment directly, which is the key component of high-voltage and low-voltage apparatus. Nowadays, all fields of mid-voltage and above are occupied by vacuum switch. The invention of contactor material CuCr promotes the development of electrical contractor material and vacuum switch though the weakness can not be ignored. This paper makes a study and analysis about the performance of traditional electrical contractor material WCu. Its believed that alloy WCu has the high conductivity and high thermal conductivity of W, and the ability to improve applying condition and reduce electrical corrosion of Cu. So the experiment is made to test electrical characteristics of material WCu which is doping with different element. The performance of a new electrical contractor material, named Ti3SiC2, which is better than alloy WCu is put forward. This material meets the requirement, including high voltage, huge capacity, small scale, for switching equipment to develop grid, as the new material has advantage of low density, high modulus, high melting point, and antioxidant and so on. The successful application improves its superiority in the field of electrical contractor material.
With the extended applications of hexagonal silicon carbide (h-SiC) in the various fields, particularly in the application of the electronic devices, more and more attentions have been focused on the micro structures as well as their physical properties of h-SiC surface. In this study, we have performed the first principal calculations to compare the formation energies of four typical defects (Vc, Vsi, CI and SiI) on the 4H-SiC (0001) surface as well as in the interior layers. Due to the surface reconstruction and the reduced lattice constrain, the optimized structures of the defects on/near the 4H-SiC (0001) surface are quite different from the ones in the deeper layers. The distinguished formation energies as function of chemical potential indicate that we may control the defects concentrations in different layers by tuning the environmental conditions. This theoretical work provides a significant understanding to the formation mechanism of the point defects on the 4H-SiC surface, and paves a way to the modification of the SiC surface via electron irradiation or ion implantation with micro-defects introduced.
Program slicing is a program analysis and understanding of technology. Sequence fault localization refers to the use of specific methods for faults in the program. Currently, the research program fault positioning is more and more people's attention and gets some results which is the more mainstream software fault localization method. Program slicing technique currently used to locate the fault procedures, which primarily to take advantage of dynamic slicing technique. Based on the full analysis of the advantages and disadvantages on the basis of previous work, we propose a flexible slicing rule and give a new method based on the slicing rule.
Solar energy is the inexhaustible,enewable Energy. The solar cell is the solar light energy into electricity. The unique advantages of solar cell. Potential, more than wind, hydro, geothermal energy, nuclear energy and other resources, is expected to become the main pillar of power supply in the future. This paper studies that the main parameters of monocrystalline crystal silicon solar battery: the junction depth and superficial concentrations influence on electrical characteristics of monocrystalline silicon solar battery. The result shows that for maximum efficiency, it is bound to get the largest possible open circuit voltage, short circuit current and fill factor of the product, therefore, it is necessary to control these two parameters, the junction depth and doping parameters. If the junction depth is constant, with the increased superficial doping concentration of monocrystalline silicon solar battery, the photoelectric conversion efficiency of the battery increases slowly at first and then rapidly decreases, and the deeper the junction depth is, the more obvious trend of the photoelectric conversion efficiency is.
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