大功率IGBT器件及其组合多时间尺度动力学表征研究综述

在提出电力电子器件及其组合多时间尺度动力学表征需求的前提下,以目前常用的全控型电力电子器件——绝缘栅双极晶体管(Insulated Gate Bipolar Transistor,IGBT)为例,系统分析并归纳了目前在IGBT及其组合多时间尺度动力学表征研究方面的进展和成果,包括作为基础的大功率IGBT及其组合多时间尺度电热瞬态建模方法、基于模型的大功率IGBT模块失效量化表征方法以及用于辅助分析的IGBT组合多速率仿真方法。此外,介绍了基于IGBT多时间尺度模型的装置应用设计案例。从建模方法、可靠性评估、仿真手段以及应用设计四个方面系统全面地阐述了大功率IGBT及其组合多时间尺度的动力学表征方法,可为电力电子混杂系统的精确设计提供电力电子器件层面的理论和技术支撑。     

XNAV中的相对论效应(III)——时空测量值的坐标转换

在文献[1-3]中求得的XNAV基本方程中,时间和距离是指太阳质心系(BCRS)中的坐标量。但在实际测量中,接收机测量的时间是时钟的固有时,接收机的位置一般应以地心系(GCRS)为基准。在相对论框架内完成这两个坐标转换,使得XNAV测量方程能够直接得到应用。最后给出了完整的XNAV高精度测量方程及其在实际测量中的计算过程。     

链约束下加工时间恶化的Flow Shop排序问题

讨论作业具有线性加工时间,作业间具有链约束的两台处理机流水作业排序问题,目标函数为极小化完工时间。在作业加工时间简单线性恶化下,提出作业的非负开始和停止延迟恶化率,构造了满足约束条件的复合作业。在此基础上,给出作业间具有平行链约束的两台处理机流水作业排序问题的最优多项式算法。     

时敏打击指挥控制技术初探

分析了时敏目标打击链,介绍了压缩打击链的主要途径,描述了图像处理、战场数据管理、武器动态分配、智能代理集成等有关时敏打击指挥控制技术,为时敏打击指挥控制系统的研究提供参考。     

基于时域平均的齿轮故障诊断

提出了信号时域平均处理的新算法,解决了周期截断误差对平均结果的影响,并对测取的齿轮箱齿轮故障振动信号进行了处理。实验结果表明:该方法在齿轮故障信号的处理中能够消除背景噪声的影响,取得比较理想的效果。     

边界扫描测试在显示技术中的应用

为有效检测电路板焊接质量与器件质量,实现高精度的故障定位,提出了基于边界扫描技术与功能测试技术的解决方案。在显示产品设计中,开展可测试性设计,形成完整的边界扫描测试链;针对VRAM器件特点,提出了基于DRAM的测试方法,并设计相应的测试模型。最终,实现了对电路板的边界扫描测试,快速完成了对显示器件质量与焊接质量的有效检测。边界扫描技术与功能测试的结合,可以扩展边界扫描技术的应用范围,实现了更高的测试覆盖率。     

激光式头盔瞄准具瞄准线数学模型的建立

激光式头盔瞄准具具有结构简单、截获目标速度快、抗干扰能力强、便于实现光电转换的优点.为了进一步加深对激光式头盔瞄准/显示系统瞄准线解算技术的研究,建立了该系统瞄准线的数学模型,从而计算出头盔的方位角和俯仰角,并对相关的误差和系统的精度进行了分析估算,实践表明该模型对瞄准线的解算是完全满足要求的.     

非自伴情形下时滞抛物方程的惯性流形

利用Lyapunov-Perron方法在适当的谱间隙条件和适当小的时滞假设下,证明了一类非自伴算子情形下半线性时滞抛物方程惯性流形的存在性。     

A stochastic model for burn‐in procedures in accelerated environment

Burn‐in procedure is a manufacturing technique that is intended to eliminate early failures of system or product. Burning‐in a component or system means to subject it to a period of use prior to being used in field. Generally, burn‐in is considered expensive and so the length of burn‐in is typically limited. Thus, burn‐in is most often accomplished in an accelerated environment in order to shorten the burn‐in process. A new failure rate model for an accelerated burn‐in procedure, which incorporates the accelerated ageing process induced by the accelerated environmental stress, is proposed. Under a more general assumption on the shape of failure rate function of products, which includes the traditional bathtub‐shaped failure rate function as a special case, upper bounds for optimal burn‐in time will be derived. A numerical example will also be given for illustration. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

Transient analysis of Markov models of fault‐tolerant systems with deferred repair using split regenerative randomization

The (standard) randomization method is an attractive alternative for the transient analysis of continuous time Markov models. The main advantages of the method are numerical stability, well‐controlled computation error, and ability to specify the computation error in advance. However, the fact that the method can be computationally very expensive limits its applicability. In this paper, we develop a new method called split regenerative randomization, which, having the same good properties as standard randomization, can be significantly more efficient. The method covers reliability‐like models with a particular but quite general structure and requires the selection of a subset of states and a regenerative state satisfying some conditions. For a class of continuous time Markov models, model class C₂, including typical failure/repair reliability‐like models with exponential failure and repair time distributions and deferred repair, natural selections are available for both the subset of states and the regenerative state and, for those natural selections, theoretical results are available assessing the efficiency of the method in terms of “visible” model characteristics. Those results can be used to anticipate when the method can be expected to be competitive. We illustrate the application of the method using a large class C₂ model and show that for models in that class the method can indeed be significantly more efficient than previously available randomization‐based methods. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006