6061铝合金焊接变形的数值分析

本课题是上海汽车工业基金汽车轻量化研究工作的一部分。汽车轻量化对于节省能源、保护环境、提高安全都有着重要的现实意义,而铝合金材料的应用则是解决该问题的有效途径之一。目前,国内在这一方面尚与先进国家存在较大差距,主要是由于铝合金结构在焊接工艺上存在较大问题。国内外相关文献主要集中在焊后组织及性能的模拟,本课题旨在对铝合金结构的焊接变形进行数值分析,为制定和优化焊接工艺提供必要的参考。     

钕铁硼永磁合金烧结过程中的晶粒聚集长大及对磁性能的影响

研究了钕铁硼永磁合金烧结过程中的晶粒聚集长大现象。结果表明：合金粉末在强磁场下成型时的取向导致磁体烧结时形成织构，那些较早结合的、晶粒位向非常一致的、晶界上无第二相的晶粒合并形成尺寸较大的晶粒吞食周围的小晶粒，形成异常粗大的晶粒，即发生了晶粒的聚集长大，晶粒的聚集长大导致矫顽力的明显降低，对取向度略有改善，因而剩余磁感应强度稍有提高，但最大磁能积降低。低钕、低氧含量、富钕相分布不均匀的钕铁硼水磁合金在较高温度下烧结时容易发生晶粒的聚集长大。     

11层钢筋混凝土框架楼房爆破拆除

采用定向爆破方法拆除11层钢筋混凝土框架楼房。由于立柱的布筋情况不明,通过爆破试验确定了炸药单耗,针对不同的立柱尺寸确定爆破参数。为了有利于结构解体,在5层以上的部分大断面柱体上和梁柱节点处也布置炮孔。文中还介绍了起爆网路、安全防护措施及爆破效果。     

DDV一Ⅲ一EP型动态粘弹谱仪在高聚物研究中的应用

本文在简要介绍ＤＤＶ一Ⅲ一ＥＰ型动态粘弹谱仪的结构和原理的基础上，通过采用高聚物的结构对动态力学性能影响的实例，介绍了动态粘弹谱仪在高聚物研究中的应用。     

Robust ℋ︁∞ filtering for uncertain Markovian jump linear systems

This paper investigates the problem of ??_∞ filtering for a class of uncertain Markovian jump linear systems. The uncertainty is assumed to be norm‐bounded and appears in all the matrices of the system state‐space model, including the coefficient matrices of the noise signals. It is also assumed that the jumping parameter is available. We develop a methodology for designing a Markovian jump linear filter that ensures a prescribed bound on the ??₂‐induced gain from the noise signals to the estimation error, irrespective of the uncertainty. The proposed design is given in terms of linear matrix inequalities. Copyright © 2002 John Wiley & Sons, Ltd.     

低能区(e,2e)反应的多重散射理论

对文献［７］发展的（ｅ，２ｅ）反应多重散射理论做了改进用得到的波函数计算了能量为５４４ｅＶ的（ｅ，２ｅ）反应的截面，结果表明改进后的多重散射理论与实验符合较好     

Quantized H∞ Control for Networked Systems with Communication Constraints

The problem of quantized H_∞ control for networked control systems (NCSs) subject to time‐varying delay and multiple packet dropouts is investigated in this paper. Both the control input and the measurement output signals are quantized before being transmitted and the quantized errors are described as sector bound uncertainties. The measurement channel and the control channel packet dropouts are considered simultaneously, and the stochastic variables satisfying Bernoulli random binary distribution are utilized to model the random multiple packet dropouts. Sufficient conditions for the existence of an observer‐based controller are established to ensure the exponential mean‐square stablility of the closed‐loop system and achieve the optimal H_∞ disturbance attenuation level. By using a globally convergent algorithm involving convex optimization, the nonconvex feasibility can be solved successfully. Finally, a numerical example is given to illustrate the effectiveness and applicability of the proposed method.     

一种基于浮动优先级的IEEE 802.11e MAC层机制

在研究了IEEE802.11eEDCF(EnhancedDistributedCoordinationFunction)机制的基础上,提出了一种基于浮动优先级IEEE802.11e的MAC层机制—F-EDCF(Floating-EDCF).该方法通过修改EDCF的优先级控制方式,提供一种公平、高效的接入机制.在F-EDCF机制下,各个移动基站(STA)通过和接入点(AP)进行协调以调整STA内各队列的初始竞争窗口(CWMin),进而改变接入信道的优先级.仿真结果表明,F-EDCF机制下各队列所得到的系统资源比EDCF更好的符合了QoS的规范.     

VIMS: A Video Information Management System

Video data management is fast becoming one of the most importanttopics in multimedia databases. In this paper, we describe thedevelopment of an experimental video information management system,called VIMS, being implemented at the Hong Kong University ofScience & Technology, which employs two fundamental components—i)a Video Classification Component (VCC) for the generation of effectiveindices necessary for structuring the video data, and ii) a ConceptualClustering Mechanism (CCM) having extended object-oriented featuresand techniques. By incorporating CCM concepts and techniques togetherwith the classified features and indices generated from the VCC, theinformation management system enables users to form dynamically, among other things, video programs(or segments) from existing objects based on semantic features/indexterms. A prototype of this system has been constructed, using apersistent object storage manager (viz., EOS), on Sun4 workstations.     

Use of the nuclear reaction for diagnostics of energetic particles in burning plasmas

Application of reaction-produced γ-rays to diagnostics of energetic particles in burning plasmas is analyzed. Particularly, we focus on 0.981 MeV γ-rays emitted in the nuclear reaction solely governed in the plasmas by energetic tritons. It is shown that these γ quanta can serve as a promising tool to diagnose α knock-on tritons and α-particles confined in burning DT plasmas. Key parameters of the α knock-on triton population and the α-particle confinement property can be obtained by comparing the experimental γ-ray yield and spectrum with theoretical slowing-down calculations. Even if the γ-ray spectral shape cannot be acquired, one can monitor densities of these tritons and α-particles at energies of 0.6–1.8 MeV and 2.0–3.5 MeV, respectively, in a nearly steady-state plasma. The 0.981-MeV photons also would help to display time evolution of the α-particle population in experiments of deuterium plasmas with pulsed tritium beam shots.