复杂平面区域的三角网格生成算法

为生成复杂平面区域的有限元网格,提出了基于网格细化的三角网格生成算法.该算法首先采用耳尖移除法对区域边界做三角划分,得到粗略的初始网格.提出Delaunay优化平分方法,根据网格密度细化初始网格,该网格细化方法结合最长边平分技术与Delaunay边交换技术,可有效提高内点生成与单元细分的质量.实验表明,基于Delaunay 优化平分的三角网格生成算法可对任意平面域进行网格剖分,生成符合有限元计算要求的高质量三角网格.     

Analysis and optimal design of discrete order picking technologies along a line

Order picking accounts for most of the operating expense of a typical distribution center, and thus is often considered the most critical function of a supply chain. In discrete order picking a single worker walks to pick all the items necessary to fulfill a single customer order. Discrete order picking is common not only because of its simplicity and reliability, but also because of its ability to pick orders quickly upon receipt, and thus is commonly used by e‐commerce operations. There are two primary ways to reduce the cost (walking distance required) of the order picking system. First is through the use of technology—conveyor systems and/or the ability to transmit order information to pickers via mobile units. Second is through the design—where best to locate depots (where workers receive pick lists and deposit completed orders) and how best to lay out the product. We build a stochastic model to compare three configurations of different technology requirements: single‐depot, dual‐depot, and no‐depot. For each configuration we explore the optimal design. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Scheduling of depalletizing and truck loading operations in a food distribution system

This paper studies a scheduling problem arising in a beef distribution system where pallets of various types of beef products in the warehouse are first depalletized and then individual cases are loaded via conveyors to the trucks which deliver beef products to various customers. Given each customer's demand for each type of beef, the problem is to find a depalletizing and truck loading schedule that fills all the demands at a minimum total cost. We first show that the general problem where there are multiple trucks and each truck covers multiple customers is strongly NP‐hard. Then we propose polynomial‐time algorithms for the case where there are multiple trucks, each covering only one customer, and the case where there is only one truck covering multiple customers. We also develop an optimal dynamic programming algorithm and a heuristic for solving the general problem. By comparing to the optimal solutions generated by the dynamic programming algorithm, the heuristic is shown to be capable of generating near optimal solutions quickly. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2003     

燃气轮机实际简单循环熵产分析

针对燃气轮机实际简单循环,应用熵产分析,对循环各部件不可逆损失分配情况进行分析,并给出实例计算.结果表明,燃烧室不可逆损失最大,其次是排气过程.     

Designing a screening experiment for highly reliable products

Within a reasonable life‐testing time, how to improve the reliability of highly reliable products is one of the great challenges to today's manufacturers. By using a resolution III experiment together with degradation test, Tseng, Hamada, and Chiao (1995) presented an interesting case study of improving the reliability of fluorescent lamps. However, in conducting such an experiment, they did not address the problem of how to choose the optimal settings of variables, such as sample size, inspection frequency, and termination time for each run, which are influential to the correct identification of significant factors and the experimental cost. Assuming that the product's degradation paths satisfy Wiener processes, this paper proposes a systematic approach to the aforementioned problem. First, an intuitively appealing identification rule is proposed. Next, under the constraints of a minimum probability of correct decision and a maximum probability of incorrect decision of the proposed identification rule, the optimum test plan (including the determinations of inspection frequency, sample size, and termination time for each run) can be obtained by minimizing the total experimental cost. An example is provided to illustrate the proposed method. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 514–526, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10024     

More on the search for an infiltrator

We have asymptotically solved a discrete search game on an array of n ordered cells with two players: infiltrator (hider) and searcher, when the probability of survival approaches 1. The infiltrator wishes to reach the last cell in finite time, and the searcher has to defend that cell. When the players occupy the same cell, the searcher captures the infiltrator with probability 1 ? z. The payoff to the hider is the probability that the hider reaches the last cell without getting captured. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 1–14, 2002; DOI 10.1002/nav.1047     

一种基于知识的作战计划系统设计

作战计划系统是复杂的问题求解系统,在军事领域的各个方面发挥着重要的作用。介绍了当前一些主要的作战计划辅助生成系统及其特点,分析比较和归纳整理了当前军用计划系统所采用的一些常见规划技术和优缺点,重点分析了作战计划系统中的智能规划技术。在此基础上,提出了一种基于知识的作战计划辅助生成系统的开发设想,构建了系统知识库,系统采用层级任务网络规划技术,给出了这种规划技术的理论框架和算法过程,并且把这种技术与多主体规划技术相结合,辅助实现军事作战任务的逐层分解与规划优化,进而生成完整的行动序列,较好地解决了作战计划辅助生成问题。     

协议测试中测试序列生成方法综述

文章在介绍协议一致性测试基本概念的基础上,重点列举了测试序列的几种生成方法。对目前广泛采用的形式化描述模型,重点介绍其中基于有限状态机模型的测试序列生成方法,同时对基于扩展有限状态机以及确定有限状态机的测试序列生成方法也进行了介绍。文章对每一种方法介绍了其原理并分析了其使用中的局限。文章最后指出了在协议测试中面临的问题和进一步研究的方向。     

模糊多属性群决策与潜艇作战方案优选

分析了潜艇作战方案的优选实质是一个模糊多属性的群决策过程,建立了模糊多属性群决策的一般模型,介绍了一种以模糊理想解与模糊负理想解同时作为参照基准,以海明距离作为测度工具,以相对贴近度作为衡量标准的模糊折衷型多属性群决策方法,应用实例表明此方法可行有效。     

搜索路径给定时的搜索对策问题及其应用

搜索路径给定时的最优搜索方案问题,也可以理解为是关于搜索者和目标的二人对策问题,主要讨论了当搜索路径给定时的单个搜索者和单个目标的搜索对策问题。首先根据问题的特点,利用动态规划和迭代的方法,确定关于目标逃逸路径混合策略的最优分区,证明该分区是多面体凸集;针对目标不同逃逸路径的分区,求出搜索者的最大期望收益,再将问题转化为二人有限零和对策,计算出搜索者的支付矩阵,确定最优搜索策略。最后结合海军护航行动,对我舰载直升机搜索小型海盗船进行分析和计算,说明搜索路径给定时的最优搜索对策对于双方的资源分配和提高搜索效率具有一定的应用价值。