Reliable grading robust stabilization for uncertain time-varying systems via dynamic compensator

A new general model for uncertain time-varying parameters and a new measure sensor failure model are presented, and the problems of both grading robust stabilization and reliable grading robust stabilization for such systems are studied. By the Lyapunov stability theory and matrix algebra method, some sufficient criteria for the above two control problems are established in quasi-linear matrix inequalities (Q-LMIS) forms. In view of linear matrix inequality (LMI) approach, a solving procedure for the Q-LMIS problem is proposed. The solvability of the Q-LMIS problem can be improved obviously by adding some LMI constraints to the Q-LMIS. Based on the two Q-LMIS criteria, a grading robust stable control strategy, namely, the controller with different energy is acted on the system with different uncertain parameter range, is presented. The numerical simulating results show that the grading robust stable control strategy for the robust stabilization of uncertain systems has important theoretical and practical significance.     

矿井煤岩体变形失稳问题的研究

本文对矿井中几种变形失稳现象:煤体冲击地压、矿震、顶底板冲击地压及煤与瓦斯突出,分别建立了煤岩体压缩、剪切、拉伸、固液耦合失稳模型及失稳判别准则,初步构画了矿井煤岩体失稳问题的框架.     

串联可修系统与单部件可修系统之关系

本文给出了串联可修系统与单部件可修系统在可靠性指标上的一些数量关系,证明了在一定条件下串联可修系统可靠性指标的计算可以转化为单部件的情况。作为列子,本文还求出了一个n部件串联可修系统的可靠性指标。     

黄道婆对手工棉纺织生产发展的贡献

本文根据宋末元初之际,江南地区的社会经济和纺织技术发展状况,以及海南岛黎族人民的植棉和棉纺织技术发展水平,探讨了元代杰出的纺织家黄道婆对上海地区棉纺织业生产发展的贡献。作者认为黄道婆的主要贡献可以概括为三个方面:一.手工棉纺织生产机具上的革新和创造,特别是发明了被后世人们称为“黄道婆纺车”的供纺棉用的脚踏三锭纺车;二.开发了棉织物的新品种,特别是色织棉布和提花棉织物,创造了名扬天下的“鸟泥泾被”;三.推动了以上海县为中心的松江府一带的手工棉纺织生产的商品化过程,在松江府发展为全国最大的手工棉纺织业中心,有“衣被天下”之誉。     

航炮寿命分布检验及可靠性评估

该文根据10门AM23航炮寿命试验的数据,进行了寿命分布形式的检验,证明航炮平均寿命分布可以用指数分布形式来描述。在此基础上,根据寿命试验数据对AM23航炮的平均无故障发数(MRBF)进行了评估,确定了该种航炮的MRBF点估计值和双侧区间的上、下限值。这些可靠性数据可供AM23航炮生产、使用部门参考。     

同时算出结构可靠指标和验算点值的快速收敛蒙特卡罗法

基于结构可靠指标的几何涵义，本文提出一种用蒙特卡罗法计算结构可靠指标及验算点的方法．该法通过数学处理，使随机抽样只限于在失效边界上进行，并在此基础上寻找出坐标原点到失效面的最短距离以及相应点的坐标值，从而获得可靠指标和验算点值．算例表明，该法收敛快、精度高、模拟次数与失效概率大小无关，完全可用于各种工程结构的可靠度计算．本文对某重力坝段进行了可靠度计算，获得满意的结果．     

面板堆石坝动力破坏计算方法研究

提出了面板堆石坝的动力破坏准则；利用有限元法对面板堆石坝进行动力破坏计算，可以得到坝体的潜在破坏区及其扩展过程。将该方法用于模型面板堆石坝的动力破坏计算，得到和模型动力破坏试验较为一致的结果，并用该方法计算了一座面板堆石坝在地震作用下的破坏过程。     

计算机故障分析与排除方法

本文介绍了AppLE—Ⅱ微机一些常见的故障和故障检测方法;阐述了如何判断故障出现在电源、主机和磁盘驱动器上的步骤;给出了主要常见故障的排除方法。     

AN ANALYSIS OF DYNAMIC PERFORMANCE OF BACK REST OF WEAVING MACHINERG

Periodic variations of warp tension during a weaving cycle results in corresponding variationsof back rest position.However,the oscillation of back rest,in turn,shows effect on the variation ofdynamic warp tension.As a force transfer medium,warp yarn,with specific dynamic performances,is certainly one of the factors influencing the movement of back rest.In this paper,warp yarn istreated as a viscoelastic medium in studying the dynamic behaviours of back rest.A mathematicalmodel of a back rest system is developed based on the automatic control theory.Several factors arelisted,which show influences on the performances of the back rest system.Analytical work is car-ried out to identify the effects on the frequency response of the back rest systen resulting from vari-ations of such parameters as the modulus of elasticity,of both fast-elastic and slow-elasticdeformations,and viscosity coefficient.     

指数分布下可靠性Bayes验证

本文在指数分布场合下,利用历史试验数据和工程经验所提供的先验信息,给出失效率和平均无故障工作时间的Bayes验证试验的抽样方案.