NiTi形状记忆合金管双轴疲劳超弹性行为

采用国产NiTi形状记忆合金,在Af温度以上对其进行比例、非比例循环疲劳,结果表明:随着加载路径的非比例度的增加,稳定的平台应力和疲劳寿命降低而循环过程中的残余应变和马氏体的起始转变应力增加.     

西沃石窟及相关问题研究

西沃石窟是黄河中下游岸边的唯一一处北魏石窟。它的建造风格兼承云冈与龙门;尤其是一号窟,在内容上弥补了龙门石窟之不足。其建造目的,除镇水外,还是为了连通豫晋之间的水上通道;石窟上的栈道遗存、牛鼻形孔洞等,对研究黄河漕运史具有一定的现实意义。     

A minimax optimal control strategy for uncertain quasi-Hamiltonian systems

A minimax optimal control strategy for quasi-Hamiltonian systems with bounded parametric and/or external disturbances is proposed based on the stochastic averaging method and stochastic differential game. To conduct the system energy control, the partially averaged Ito stochastic differential equations for the energy processes are first derived by using the stochastic averaging method for quasi-Hamiltonian systems. Combining the above equations with an appropriate performance index, the proposed strategy is searching for an optimal worst-case controller by solving a stochastic differential game problem. The worst-case disturbances and the optimal controls are obtained by solving a Hamilton-Jacobi-Isaacs （HJI） equation. Numerical results for a controlled and stochastically excited DulTlng oscillator with uncertain disturbances exhibit the efficacy of the proposed control strategy.     

On the uncertain variable structure systems with bounded controllers

In this paper, we propose a method to estimate the asymptotic stability region (ASR) of uncertain variable structure systems with bounded controllers. Using linear matrix inequalities (LMIs) we estimate the ASR and we show the exponential stability of the closed-loop control system in the estimated ASR. We also give simple LMI-based algorithms for estimating the ASR and designing a switching surface which will make the estimated ASR big. Finally, we give numerical examples in order to show that our method can be better than the previous results for a certain class of uncertain variable structure systems with bounded controllers.     

Study on one-dimensional consolidation of saturated soil with semi-pervious boundaries and under cyclic loading

The variation of effective stress ratio of stratfied soil with semi-pervious boundaries and under cyclic loading was analyzed on the basis of Terzagh's one-dimensional consolidation assumptions. A solution by Laplace Transform was obtained for the case when the soil was under time-varied loading. With numerical inversion of Laplace Transform, some useful results were obtained for several kinds of commonly encountered loadings. The results can be meaningful in engineering practice. Project supported by the National Natural Science Foundation of China (No. 59908012) and Fok Ying Tung Education Fundation (No. 81067), Education Ministry of China.     

GH4169合金高温多轴低周疲劳寿命预测

基于临界面模型的方法提出一个新的(修正的)多轴低周疲劳损伤准则.该准则与目前的临界面法所不同的是,在预测多轴低周疲劳寿命的模型中,同时考虑临界面上最大剪应变和正应变在不同加载路径下对多轴低周疲劳损伤的贡献。试验结果表明,本文提出的多轴低周疲劳寿命预测模型,对于GH4169合金高温多轴疲劳寿命估算具有较高的准确性。     

一种基于Matlab的大文本试飞数据绘图策略研究

为满足大文本试飞数据图形可视化分析需求,基于Matlab语言对大文本试飞数据的可视化绘图策略进行探讨。结合试飞数据绘图分析特点,重点研究大文本试飞数据绘图中的关键策略：①数据加载方式选择;②多参数对比曲线图绘制方法;③绘图操作的继承。通过关键绘图策略程序,减少了试飞数据载入内存时间,完成了3种多参数对比图绘制,达成重复绘图操作的有效继承。该关键策略可在大文本试飞数据可视化绘图分析中发挥关键作用,提高试飞数据绘图分析效率。     

超弹性形状记忆合金丝力学性能试验研究

超弹性是形状记忆合金（SMA）的重要特性之一。通过试验,研究了应变幅值和加卸载循环次数对SMA丝应力诱发马氏体相变应力、残余应变、最大相变应变和耗能能力的影响。研究结果表明,超弹性SMA丝具有良好力学性能,应变幅值对它的耗能能力具有较大的影响,循环次数的增加可使其力学性能更加稳定。     

Decentralized impulsive control for a class of uncertain interconnected systems

INTRODUCTIONWiththedevelopmentofscienceandtech-nology,thestructuresofcontrolsystemsaregettingmoreandmorecomplicated.Thiskindofsystemhasthecharacteristicoflargedimension,andin-terconnectionamongsubsystems.Generally,thiskindofsystemiscalledinterconnectedlargesystem.Thestudyofinterconnectedsystemsismotivatedbyquiteanumberofpracticalapplicationsrangingfrompowernetworks,transportation,aerospace,economics,management,andsoon.Thestrategiestocontrolinterconnectedsystemsaredividedintotwokinds:centr…     

基于Jigsaw Proxy的加载网页的设计与实现

Jigsaw是W3C论坛的一个用Java语言实现的增强型Web服务器平台。它提供了HTTP方式的Proxy服务。通过对Jigsaw资源的配置不仅可以让Jigsaw成为一个代理服务器，而且还可以使代理服务器通过用户添加的动态扩展模块来实现附加功能。利用Jigsaw，将用户定义的Filter资源绑定在Frame上，在不改变原网页的结构的情况下，实现加载网页的功能，使得Jigsaw的适应范围更广，也更灵活。