混合EMS型磁浮列车的悬浮磁铁设计与分析

研究适用于EMS型磁浮列车的全尺寸电磁永磁混合悬浮磁铁的设计问题。通过比较永久磁铁的不同安装位置的影响,给出混合磁铁的结构方案。根据混合磁铁吸力公式,得出只有在永久磁铁矫顽力大于一定值时利用混合磁铁才能减小悬浮能耗。分析了混合磁铁的设计要求,研究满载起浮、稳态悬浮、空载吸死三种典型情况下对电磁线圈窗口高度的约束,得出混合磁铁的优化设计参数。最后利用Ansoft有限元磁场分析软件对钕铁硼永磁材料的拼装影响进行分析,给出校正后的悬浮磁铁设计结果。     

基于时频的逆合成孔径雷达的距离—瞬时多普勒成像方法

为了对机动目标进行ISAR成像,以在时间和频域同时具有高分辨率的时频变化替代傅氏变换作谱分析,得到机动目标距离—瞬时多普勒像。实测数据处理结果表明,与直接用距离—多普勒(R D)算法相比,该方法得到的图像质量有明显提高。     

一种新的Weibull分布恒定应力加速寿命试验分析方法

分析了Weibull分布恒定应力加速寿命试验常用的二步分析方法存在的不足 ,建立了一种新的构造数据分析方法。考虑到分布参数的相关性 ,该方法引入了Weibull分布特征寿命参数的二次估计 ,在模型拟合优度上高于原来的二步分析方法 ,使分析精度得到了改善。同时 ,该方法避免了原来二步分析方法的查表过程 ,便于软件实现和工程实际应用。     

Solving generalized transportation problems via pure transportation problems

This paper investigates certain issues of coefficient sensitivity in generalized network problems when such problems have small gains or losses. In these instances, it might be computationally advantageous to temporarily ignore these gains or losses and solve the resultant “pure” network problem. Subsequently, the optimal solution to the pure problem could be used to derive the optimal solution to the original generalized network problem. In this paper we focus on generalized transportation problems and consider the following question: Given an optimal solution to the pure transportation problem, under what conditions will the optimal solution to the original generalized transportation problem have the same basic variables? We study special cases of the generalized transportation problem in terms of convexity with respect to a basis. For the special case when all gains or losses are identical, we show that convexity holds. We use this result to determine conditions on the magnitude of the gains or losses such that the optimal solutions to both the generalized transportation problem and the associated pure transportation problem have the same basic variables. For more general cases, we establish sufficient conditions for convexity and feasibility. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 666–685, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10034     

稳像火控系统误差分析

通过对坦克稳像火控系统预测模型和目标运动状态测量的误差分析,提出提高测量精度和射击命中率的措施。     

微波消解预处理技术用于食品微量元素分析的研究

介绍微波消解预处理技术用于食品消解的一般实验方法、影响消解效果因素分析及相应的最佳条件控制;用AAS法测定预处理样品中的微量元素,结果良好.     

关于意境问题的思考

长期以来 ,在中国古典诗歌的研究中 ,意境都是作为评价诗歌艺术水准的重要标准 ,有时甚至是惟一标准。这种评价标准直接限制了评价者的视线 ,也不符合诗歌创作的实际。本文就此进行了辨析 ,并明确指出 :意境本身只是一个诗歌评价的艺术概念 ,在不同的环境条件下 ,意境本身也是有高低之分的。     

基于马尔可夫分析的人才拥有量研究

基于马尔可夫分析理论,给出了人才拥有量预测的马尔可夫模型,并且讨论了模型中转移概率的确定及模型的预测质量等问题.     

When is model complexity too much? Illustrating the benefits of simple models with Hughes' salvo equations

The simulations that many defense analysts rely upon in their studies continue to grow in size and complexity. This paper contrasts the guidance that the authors have received—from some of the giants of military operations research—with the current practice. In particular, the analytic utility of Hughes' simple salvo equations is compared with that of the complex Joint Warfighting System (JWARS), with respect to JWARS' key performance parameters. The comparison suggests that a family of analytic tools supports the best analyses. It follows that smaller, more agile, and transparent models, such as Hughes' salvo equations, are underutilized in defense analyses. We believe that these models should receive more attention, use, and funding. To illustrate this point, this paper uses two very simple models (by modern standards) to rapidly generate insights on the value of information relative to force strength. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003     

Optimal stopping in software testing

In this paper we address the problem of how to decide when to terminate the testing/modification process and to release the software during the development phase. We present a Bayesian decision theoretic approach by formulating the optimal release problem as a sequential decision problem. By using a non‐Gaussian Kalman filter type model, proposed by Chen and Singpurwalla (1994), to track software reliability, we are able to obtain tractable expressions for inference and determine a one‐stage look ahead stopping rule under reasonable conditions and a class of loss functions. © 2002 Wiley Periodicals, Inc. Naval Research Logistics, 2003