Effect of Air Oxidation on the Thermophysical Properties of a Zirconium Alloy

The results of an experimental study of the effect of air oxidation on the temperature dependence of the heat capacity and normal spectral emissivity (for the wavelength of 0.65 m) of the zirconium alloy E635 (1.3 mass% Sn, 0.3 mass% Fe, 1 mass% Nb) are presented. The subsecond resistive pulse heating technique has been used. The samples were heated in ambient air by single and multiple cyclic pulses.     

Development of Spectral Selective Multilayer Film for a Variable Emittance Device and Its Radiation Properties Measurements

A smart radiation device (SRD) that is a variable emittance radiator has been developed as a thermal control material for spacecraft. The SRD has the unique feature of large variation of the total hemispherical emittance _H near room temperature. The _H of the SRD changes depending on its temperature. However, there is a drawback of a large solar absorptance _S. It is too large to use as a thermal control material for spacecraft. In order to reduce the large _S, spectral selective multilayer film was developed. This multilayer film reflects solar radiation and transmits far-infrared radiation to maintain the variation in the _H of the SRD. This paper presents thermal radiative properties of the SRD with spectral selective multilayer film. The multilayer film was designed by using a genetic algorithm (GA). The designed multilayer film was evaporated on the surface of the SRD by the electron beam evaporation method. The experimental results of _S and _H of the SRD with the multilayer film agreed well with calculated results.     

Effect of Swinging of Vibration Sensors on Their Calibration Error

The requirements of GOST ISO 5347-1–96 for restricting the level of vibration sensor swinging during calibration are considered. It is demonstrated that that section of the standard must be made more stringent. The error of measurement of small vibration amplitudes (less than 0.2 m) during measurements is estimated from a spectral analysis of an interferometer signal.     

正定Hermite矩阵特征值的相对扰动界

给出了正定Hermite矩阵特征值的一个新扰动界,同以往的结论相比我们的界形式上更简洁而且新的扰动界在合同变换下保持不变。     

基于“NTN”校准法的相位解卷绕技术

基于“NTN”校准理论,分析了“NTN”校准法中的相位卷绕问题及其带来的误差.提出了适用于“NTN”校准法的相位解卷绕技术,给出了使用相位解卷绕技术的“NTN”校准法的计算机仿真结果.     

"NTN"校准技术中的"Kick-out" 脉冲的仿真研究

本文基于微波二极管取样电路,用PSPICE软件,对“NTN”校准技术中的“Kick-out”脉冲进行了仿真研究。分别研究了选通脉冲源内阻,微波二极管诸参数（管壳电容Cp,引线电感Ls,结电容Cj和扩散电阻Rs)、取样脉冲的对称性和取样电路的对称性,对“kick-out”脉冲的影响。     

Kinematic calibration of a class of parallel kinematic machines (PKM) with fewer than six degrees of freedom

The accuracy of parallel kinematic machines (PKM), particularly machine tools is an important performance index. It has been acknowledged that kinematic calibration is a practical and economical way for enhancing the accuracy of PKM systems. The procedure usually involves four steps, i.e. error modeling, measurement, identification and implementation[1,2]. So far, most work on the kinematic calibration of PKM systems has focused upon the objects with six degrees of freedom (DOF)[3—13]. A…     

电能表装置输出功率稳定度测量与计算的探讨

针对目前国内高精度功率、电能表标准装置功率稳定度指标测试中的一些实际问题进行了讨论,并通过实例进行了分析,对装置输出功率稳定度指标的测量和计算提出了看法。     

基于谱减法的改进语音增强方法

语音增强技术是解决噪声污染的一项强有力的预处理技术.谱减法通过处理后的语音中会留下所谓的"音乐噪声",针对这个问题,提出了一种多带谱相减与感觉加权相结合的语音增强方法.对带噪语音进行多带谱相减,并根据人的听觉掩蔽特性,对多带谱相减后的信号进行感觉加权,从而进一步降低背景噪声.在语音失真和噪声抑制之间取得良好的折中,减少语音的听觉失真,有效地抑制"音乐噪声",提高语音的清晰度.     

基于ADE7758芯片的GPRS网络电能表的设计与实现

本文介绍了ADE7758电能计量芯片在非洲GPRS网络电能表中的应用,重点阐述了视在电能计量及其校准方法,ADE7758数字软校表流程及其算法,以及ADE7758的相位校准算法。