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.     

HISTORICAL PROCEDURES AND G-DSG METHOD BASED MANUFACTURING PLANNING

Oriented to CAD/CAM seamless integration, this paper presents an idea for synthetically considering the qualitative history model, which represents the whole course of modeling, and the quantitative geometry model, which contains the extended Brep model, CSG and feature pedigree. History model building captures in background the dynamic interactive definition of engineering requirement and then explicitly conveys the original intention to successive application layers, which isc onductive to the decision support of manufacturing planning in not only automatic geometry re-constructing but also machining set-up. G-DSG theory as an earlier achievement is applied to generate the topology-independent generalized mid-model as an input to manufacturing planning, which istherefore simplified and its accuracy is simultaneously improved. Manufacturing planning lays emphasis on optimizing the mapping in both geometry and function from part itself to detail machining scheme. Comparatively, process planning pays more attention to the mapping to those items like tool, fixture, etc. Theoretically, such an idea is also beneficial to realizing the parametric NC machining trajectory generation and maintaining its dynamic consistency with the update of the design model.     

矢量二元收扩喷管热射流复杂流场特征研究

提出了一种二元收－扩矢量喷管的概念,用热射流实验台对二元矢量喷管进行了过膨胀状态下的喷管模型热态实验。测量了喷管壁面静压和喷管出口总压分布,用红外热成像技术给出了二元喷管热射流场的清晰画面,并对流场特征进行了描述和分析。研究表明,在非设计状态,二元喷管管内有明显的流动分离现象,喷口射流总压严重畸变,在热射流流场中,射流流场呈现双势核结构。