用时序展开法求解瞬时无耗传输线方程

本文用时序展开法直接在时域中求解了任意终端和输入端时无耗时变传输线方程。给出了这个问题的一般解。此方法简单,结果的物理意义明确,对分析准行波系统的时域问题具有一定的参考价值。     

中立型泛函微分方程解的有界性

对于有限时滞中立型泛函微分方程,利用Liapunov泛函的方法,研究了方程解的有界性,得到了便于应用的判据。     

泛函微分方程x’（t）＝a（t）f（x（μ（x（t））））的解的性态

本文研究偏差变元依赖状态自身的泛函微分方程ｘ’（ｔ）＝ａ（ｔ）ｆ（ｘ（μ（ｘ（ｔ））））（１）的解的渐近性态。进一步推广或部分推广Ｄｕｎｋｅｌ［１］、Ｅｄｅｒ［２］、Ｗａｎｇ［３］、吴汉忠［４．５］及作者［６～８］等人的工作。文中使用了一些新方法,也得到了一些新结果。     

基于混合粒子群优化的多目标决策新方法

多目标优化问题中的一个关键在于合理地评判各有效解的优劣。通过引入灰色系统理论中灰色关联度的概念作为评判准则,结合粒子群优化算法进行有约束多目标规划问题的研究。提出了一种新的不可行解的保留策略,进化过程中以此策略保留适量的不可行解,有利于增强对约束边界附近可能的最优解的搜索,同时,针对粒子群优化算法的容易陷入局部最优的缺点,实现了以粒子群优化为载体的混合算法:即对全局极值邻域进一步混沌搜索寻优。仿真结果表明改进的算法对多目标决策问题是有效的。     

Two‐stage component test plans for testing the reliability of a series system

A system reliability is often evaluated by individual tests of components that constitute the system. These component test plans have advantages over complete system based tests in terms of time and cost. In this paper, we consider the series system with n components, where the lifetime of the i‐th component follows exponential distribution with parameter λ_i. Assuming test costs for the components are different, we develop an efficient algorithm to design a two‐stage component test plan that satisfies the usual probability requirements on the system reliability and in addition minimizes the maximum expected cost. For the case of prior information in the form of upper bounds on λ_i's, we use the genetic algorithm to solve the associated optimization problems which are otherwise difficult to solve using mathematical programming techniques. The two‐stage component test plans are cost effective compared to single‐stage plans developed by Rajgopal and Mazumdar. We demonstrate through several numerical examples that our approach has the potential to reduce the overall testing costs significantly. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 95–116, 2002; DOI 10.1002/nav.1051     

非线性耦合反应扩散系统解的存在性与脉冲同步

研究了耦合反应扩散系统整体解的存在性,并对其进行了证明。在此基础上,进一步加入脉冲条件,首次提出该系统脉冲同步的稳定性准则,得出脉冲误差系统是全局拟吸引的结论。     

新时期高校师德建设面临的问题与对策

高等教育发展对师德建设提出的新要求,应采取适当措施探讨高校师德建设的新路径和方法。     

iSIGHT在多目标优化问题中的应用研究

在工程实际中,随着设计要求的日益提高,单一的设计目标已经不能满足设计者的要求。于是多目标设计优化问题在设计领域越来越占据主导地位。目前多目标优化设计方法种类繁多,各有优劣,重点介绍优化设计框架iSIGHT,并就iSIGHT在解决鱼雷壳体结构设计中的多目标优化设计问题中的应用情况进行研究,讨论iSIGHT在解决多目标优化问题中的可行性。     

建筑外装修及外保温系统的消防安全问题及对策

建筑外部装修及外保温系统的消防安全问题日益突出,结合实际中的建筑外部装修及外保温系统现状,分析了建筑外部装修及外保温系统对消防安全的影响,分析发现建筑外部装修及外保温系统的消防安全隐患大,需要给予足够的重视,并根据实际确定了相应的对策。     

Approximating nondominated sets in continuous multiobjective optimization problems

Many important problems in Operations Research and Statistics require the computation of nondominated (or Pareto or efficient) sets. This task may be currently undertaken efficiently for discrete sets of alternatives or for continuous sets under special and fairly tight structural conditions. Under more general continuous settings, parametric characterisations of the nondominated set, for example through convex combinations of the objective functions or ε‐constrained problems, or discretizations‐based approaches, pose several problems. In this paper, the lack of a general approach to approximate the nondominated set in continuous multiobjective problems is addressed. Our simulation‐based procedure only requires to sample from the set of alternatives and check whether an alternative dominates another. Stopping rules, efficient sampling schemes, and procedures to check for dominance are proposed. A continuous approximation to the nondominated set is obtained by fitting a surface through the points of a discrete approximation, using a local (robust) regression method. Other actions like clustering and projecting points onto the frontier are required in nonconvex feasible regions and nonconnected Pareto sets. In a sense, our method may be seen as an evolutionary algorithm with a variable population size. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.