Experimental study on electrical resistivity measurement of a specimen at high temperature

A new technique is developed to measure the electrical resistivity of conductor with a nonuniform tem- perature profile. The calculation method is derived from the temperature dependence of the electrical resistivity. The apparatus consists mainly of a high temperature environmental chamber, a power circuit of heating, a twenty-wavelength pyrometer, and a scanning pyrometer. After getting the resistance from the voltage drop of the specimen, the electrical resistivity in a wide temperature range of the specimen can be obtained by our calculation model. Preliminary results of the electrical resistivity of SRM 8424 over a wide temperature range （1000-3000 K） are presented. The perfect consistency between the measurement results and the nominal values justifies the validity of this technique.     

旋转抛物面聚光器焦面能流分布的有限元分析

提出一种计算太阳能聚光器聚光焦斑能流密度分布的新方法。在考虑太阳形状、聚光器表面形状误差、跟踪误差、接收器位置误差、漫反射及接收器遮挡作用等各项光学误差和影响因素的基础上,结合旋转抛物面聚光器的光学特性,采用有限元法对焦面能流密度分布进行计算,并与文献中的结果进行比较,证明了该方法的正确性和可行性。同时又对半球形接收器和圆柱形接收器进行了实例计算,结果表明该方法不受聚光器或接收器面型的限制,算法简单,通用性也较强,从而为系统的优化设计和能流密度的测量奠定基础。