基于几何特征的飞行器RCS高效计算方法(英文)

Taking into account the influences of scatterer geometrical shapes on induced currents, an algorithm, termed the sparse-matrix method （SMM）, is proposed to calculate radar cross section （RCS） of aircraft configuration. Based on the geometrical characteristics and the method of moment （MOM）, the SMM points out that the strong current coupling zone could be predefined according to the shape of scatterers. Two geometrical parameters, the surface curvature and the electrical space between the field position and source position, are deducted to distinguish the dominant current coupling. Then the strong current coupling is computed to construct an impedance matrix having sparse nature, which is solved to compute RCS. The efficiency and feasibility of the SMM are demonstrated by computing electromagnetic scattering of some kinds of shapes such as a cone-sphere with a gap, a bi-arc column and a stealth aircraft configuration. The numerical results show that： （1） the accuracy of SMM is satisfied, as compared with MOM, and the computational time it spends is only about 8% of the MOM; （2） with the electrical space considered, making another allowance for the surface curvature can reduce the computation time by 9.5%.     

美空军开展飞机防红外导弹袭击研究

美国空军正在实施一项称之为“美国空军红外干扰策略全面评估（AFCISA）”的计划，涉及的技术内容很广泛，包括减少飞机红外信号特征的一些简便方法，如美国空军特种作战司令部已经装在C-130飞机发动机尾部的金属罩或“导管”；     

光在金属表面反射时位相跃变的研究

光在金属表面反射时的位相跃变值与入射光波波长和金属本身的光学特性有关。在用绝对光波干涉法测量量块长度时,必须解决光在量块表面反射时的位相跃变问题。对光在金属表面反射时的位相跃变问题进行了定量分析,推导出了位相跃变值的数学关系式,计算出了几种金属的实际位相跃变值,对量块等零件的光学精密测量有实用价值。     

学生难解译文之探究

本文对学生在阅读译文时难以消化译文的现象进行了分析，并就英汉两种语言区别特征作了初步的探讨。     

常客优惠筑就忠诚

常客优惠计划是民航业界普遍采 用的一种市场策略。它通过旅 客在航空公司积累里程换取免费机票或其他优惠的奖励，达到吸引经常乘机旅客，提高市场竞争力的目的。１９８１年，美利坚航空公司（Ａｍｅｒｉｃａｎ Ａｉｒｌｉｎｅｓ）建立了世界上第一个常客优惠计划，２０年来，越来越多的公商务旅客为常客优惠计划所吸引，成为航空公司的忠诚旅客，常客优惠计划也已经成为国际民航运输业普遍采用的一种非价格市场营销策略。笔者曾经在１９９７年撰文谈过这个问题，那时我国只有国航建立了常客优惠计划。时隔四年，“常客优惠计划”这个名词…     

夜听胡笳折杨柳 高高秋月照孤城－－论盛唐边塞诗中月的意象

月是盛唐边塞诗中常见的意象，经过长期的审美积淀和诗人对现实生活的深刻体悟，伴随着浩渺苍茫的宇宙时空，蕴含了阔大深远的历史意味，营造出雄浑高古的审美境界，月和孤城、胡乐组合，通过视觉和听觉的双重感受，使盛唐边塞诗画面更富立体感，意境更雄浑深远，情感更深沉含蓄。     

帧同步信号及特征码提取电路的设计

同步是数字通信中需要解决的一个重要问题。文中讨论了帧同步提取和特征码提取的问题,指出为了提高帧同步系统的性能,有必要增加同步保护和同步校核环节,并给出了实现方法和途径。在此基础上,给出了特征码提取的实现方法。     

瞬态压力测量中通道效应的修正

某些情况下，在测试瞬态压力时必须包含有连接通道，内燃机示功图的测量就是一个典型的例子，但是通道的气动特性使测录的压力波发生畸变，本文考虑了通道中的非定常，非等熵流动，并且提出了一种特殊的逆特征线法用于畸变直接进行校正，实验结果显示通道的畸变效应可以得到安全的修正。另外，本文指出在传感器的安装，维护，寿命和抗热冲击等方面，连接通道的存在反而是有利的。     

两相喷管流动研究进展

本文综述了两相喷管流动研究的进展,着重介绍了两相喷管流动控制方程的数值解以及两相喷管流动研究的实际应用。     

SYNTHETIC STRESS LIFE TESTING OF MECHATRONIC PRODUCTS UNDER VARIABLE STRESS SPECTRUM

Mechatronic products usually endure the variable stress spectrum when they operate in certain operational condition and environmental condition, which obey the Weibull distribution. In accordance with the features of mechatronic product, this paper analyzes the failure mode, its corresponding sensitive stress and the design principles of life testing profiles. Based on the above analyses, this paper presents a synthetic stress life testing method based on the hybrid Weibull distribution and its statistical method under variable stress spectrum to evaluate the reliability and life indices of mechatronic products. Because the mechatronic products have many characteristics such as high price, long life and small testing samples, the synthetic stress life testing method under variable load spectrum can simulate the real various spectra, decrease the life testing time and reduce the testing samples. So it is effective to carry out the life testing to mechatronic products. The application results of hydraulic pumps indicate that this method can easily handle the experimental data under variable amplitude spectrum, obtain the high precision parameters point estimation and confidence interval estimation and reduce the testing cost greatly.