Low-cycle fatigue properties of eutectic solders at high temperatures

This paper details the deformation mechanism and low‐cycle fatigue life of eutectic solder alloys at high temperature (around 0.8T_m). Grain boundary sliding generally nucleates a wedge‐type cavity that reduces the low‐cycle fatigue life of metals. In this study, grain boundary sliding has promoted intergranular failure contributing to the reduction in fatigue life of Sn–Ag–Cu alloy. However, grain boundary sliding has exerted no deleterious effects on fatigue resistance of eutectic Pb–Sn and Bi–Sn alloys. The phase boundary sliding with very fine microstructure induces exceptional ductility in these alloys leading to superior low‐cycle fatigue endurance for theses eutectic Pb–Sn and Bi–Sn alloys.     

一种基于PWM的半桥型开关电源

主要介绍了由SG3525组成的半桥型开关稳压电路的结构和工作原理，阐述了PWN集成电路SG3525的特性和主要功能。实践表明：该系统工作稳定，运行效果良好。     

Adaptive control of siso plants with unmodelled dynamics

In this paper we pursue a twofold aim. First we want to simplify the complexity of the classical Monopoli's scheme, the so-called ‘Augmented error signal control scheme’. Then we also wish to cope with the realistic situation in which the presence of unmodelled dynamics has to be taken into account. This latter problem has been faced in the literature by suitably modifying the adaptation mechanism in order to avoid undesired phenomena as well as to obtain an attractive stability region for the state trajectories starting from any point in a predefined initial condition set. In our case the necessity of introducing any sort of modification in the adaptation mechanism is completely avoided, but we still obtain asymptotic stability of the output error signal.     

实验应变／应力模态分析若干问题的进展评述

本文评述了实验应变／应力模态分析进展的若干基本问题。主要是：应变响应与位移响应的关系；应变频响函数矩阵的特点及其测量方法；应变模态的加权正交性及其识别方法；以及其他问题。     

珠江口盆地开平凹陷油气聚集条件分析

珠江口盆地自新生代以来,曾先后受到不同方向张应力的作用,造成了不同时期构造体系的交叉叠合.中中新世以来构造运动强烈,并具有东强西弱的特点,对油气的运移与聚集产生了重要影响.开平凹陷的剧烈断裂和断陷活动始于始新世,并在同期沉积了巨厚的文昌组.晚渐新世以后,由于断裂活动非常微弱,在成熟的烃源岩与其上地层之间缺乏有效的油源断层,因而自生自储、近距离运移可能是开平凹陷油气聚集的基本特征.在凹陷内部,因重力滑动和欠压实泥岩共同作用所形成的KPll-1构造带可能是该区最具有油气远景的地区.     

The TDCPR Management Mode of Engineering Equipment

The Three Gorges Project is a very large project,and its structure is very complex.Interna-tional advanced engineering equipment is broadly used.The state of equipment running directly influ-ences project building qualities and limited time.According to the factud conditions of the Three Gor-ges Project,the characteristics of engineering equipment are analyzed.At the same time ,some theories about equipment management are induced ,and the TDCPR management mode of engineering equip-ment of the Three Gorges Project is put forwared in order to gain the aim of managing and using equip-ment well and speeding up the project construction.     

广州中城广场主体工程施工技术

广州中城广场工程结构形式复杂，平面曲折多角。施工中在应用多种模板体系、泵送混凝土、无粘结预应力楼板及核心筒部分小平台滑模等方面，采用了多项新技术，保证了工程质量，加快了工程进度。     

分子振动态及其跃迁的激光相干控制

讨论了激光合成相干叠加态的原理及其性质 ,针对 XY2 型分子 ,证明了合成局域模振动的可行性 ,然后给出相干叠加态的跃迁几率特征 ,发现它仍表现出相干的特性 ,对之进行分析研究表明 ,分子的振动态具有可控性 ,态跃迁几率具有可控性。     

耦合腔行波管慢波结构的工作模式及其特性

耦合腔行波管慢波结构可工作于三种不同模式：正常模、简并模和反向模。应用改进的等效电路法计算了正常模腔通带和槽通带。求得的简并模耦合槽张角与实验值相符。最后讨论了反向模耦合腔行波管诱人的特点。     

潜油电动机滑行时间的自动测量

潜油电动机滑行时间是评定电动机装配质量的重要指标。鉴于手工测量电动机滑行时间存在效率低和误差较大的不足,设计了潜油电动机滑行时间自动测量系统。它通过分压电路和计算机自动测量系统测量潜油电动机定子上感应的电压变化状况,即可得到电动机滑行时间。用手工测量、波形分析和自动测量3种方法测量6种型号电动机的滑行时间,其中5种滑行时间长于3s,判定为合格;1种滑行时间短于3s,判定为不合格。3种方式测量的滑行时间具有较好的一致性,仅波形分析法得出的滑行时间比自动测量的滑行时间稍长,表明自动测量方法的精度和重复性可满足要求。