Search

Electrochemical trepanning process is known as an economical approach for manufacturing ruled surface blade made of hard-to-cut material. The machining accuracy of blade fabricated by electrochemical trepanning relies on the designed profile of cathode tool and distribution of machining gap. When trepanning blades, the electric field often concentrates at the leading and trailing edges, because the curvature radius of leading and trailing edges are much smaller than that at concave and convex parts. The local concentration of electric field will result in large difference of machining gap distribution between the blade profile and cathode profile. So, designed cathode profile cannot be obtained by simply offsetting the desired blade profile by a certain distance. In this paper, an iterative correction method is introduced to design the profile of trepanning cathode. In this method, the cathode and blade profile are divided into a series of nodes, gap between each blade node and its corresponding cathode node is differently designed based on the electric field intensity. Experiment results show that the machining accuracy of blade is improved hugely by cathode after iterative correction design. [ABSTRACT FROM AUTHOR]

The rapid growth of photovoltaic PV energy utilization and the immense potential for future use dictate a need to seriously consider the reliability of PV system. In this study, the comprehensive model to assess the reliability of large-scale and grid-connected PV system was proposed, taking account of weather condition as well as critical component failure probability. In addition, the sequential Monte-Carlo simulation was also established, combining with the developed model. And this analytical approach was successfully applied to evaluate the practical PV system in western area of China. The result showed that the reliability increased as the system capacity increased. And the simulated value become more accurate when the basic model was modified by more factors, especially by weather condition. While for the fixed-capacity system, the reliability decreased periodically as the operation time prolonged, which was mainly caused by the PV modules and inverters failure probability. [ABSTRACT FROM AUTHOR]