关于m×n型流程优化的探讨

网络图的优化,是根据一定的约束条件对网络图进行调整和改进,以达到科学安排工作,合理分配人力、物力、财力等资源,从而提高工作效率的目的。流程优化就是通过改变工作顺序,解决组织计划中出现的窝工现象。m×n型流程优化,是解决有m个单位依次进行n项活动时,如何安排各单位的顺序最优的问题。通过案例的耗时分析,提出了确定单位顺序的方法,希望对解决相似问题提供一定的参考。     

三种艉部附体方案的粘性阻力数值计算

水面船舶艉部附体不但影响船舶的阻力,而且对螺旋桨的伴流分数以及推力减额也会产生较大影响。近年来,越来越多的研究者都重视使用数值方法进行船舶附体优化设计。在分析某排水型水面船舶艉部附体特点以及优化目标后,设计出两套艉部附体优化方案。通过数值计算方法对这3种方案的船体带附体模型在不同雷诺数条件下进行三维粘性流场的数值模拟。分析比较了它们的粘性阻力和螺旋桨桨盘面处的伴流,最后得到双尾鳍附件的最优方案。     

面向多星观测调度的分层迭代算法

提出一种基于分治策略的多星观测分层调度框架,在该框架下,用蚁群优化算法把任务分配至各轨道圈次上,并利用自适应模拟退火算法求解各轨道圈次的调度问题。根据各轨道圈次调度结果的反馈情况,再调整任务分配方案,重复上述过程直到达到算法终止条件。为了提高算法的性能,在设计蚁群算法的启发式信息模型时,应充分考虑卫星调度问题的领域知识;在模拟退火算法中设计两个邻域结构,采用动态选择策略在优化过程中确定最佳邻域搜索结构。仿真实验表明,该方法有效地降低了问题求解的复杂度,尤其在求解大规模多星观测调度问题时表现出优异的性能。     

人工神经网络特征优化方法在模式识别中的应用

在模式识别中,特征量的选择及组合优化是设计模式识别系统的关键问题,它强烈地影响到分类器的设计及其性能。人工神经网络除了在模式识别中作为分类器应用之外,而且能够实现特征参数的提取。通过采用人工神经网络模型,对柴油机故障的特征量优化方法进行了研究,实现了对柴油机故障的特征提取及优化。     

保障性分析在现役装备维修资源确定中的应用

针对我军现役装备维修保障资源建设中的弊端,分析了在现役装备维修保障资源确定中实施保障性分析的可行性,并介绍了与传统保障性分析的不同点及其主要流程,从而为我军现役装备维修保障的确定与配置实施提供了一个良好的思考方向。     

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     

略论新疆旅游开发战略

实施西部大开发及中国加入世贸组织,给西部地区合理开发旅游资源带来了机遇和挑战,其中新疆的社会现状和经济状况决定了新疆旅游业面临更多的挑战,对此我们必需充分利用新疆旅游资源优势,制定合理的发展战略,促进新疆旅游业经济发展和社会进步.     

Analysis of a machine repair problem with an unreliable server and phase type repairs and services

In this paper we study a machine repair problem in which a single unreliable server maintains N identical machines. The breakdown times of the machines are assumed to follow an exponential distribution. The server is subject to failure and the failure times are exponentially distributed. The repair times of the machine and the service times of the repairman are assumed to be of phase type. Using matrix‐analytic methods, we perform steady state analysis of this model. The time spent by a failed machine in service and the total time in the repair facility are shown to be of phase type. Several performance measures are evaluated. An optimization problem to determine the number of machines to be assigned to the server that will maximize the expected total profit per unit time is discussed. An illustrative numerical example is presented. © 2003 Wiley Periodicals, Inc. Naval Research Logistics 50: 462–480, 2003     

多轴越野车辆悬架部件结构优化设计

基于有限单元法、变密度方法和车辆动力学分析方法,对某型多轴越野车辆的典型部件(前悬架摆臂)主体进行了结构优化设计研究。结果表明:通过结构优化,降低了摆臂的质量,提高了摆臂的静态、动态结构刚度和强度。     

铝热焊接工艺参数优化研究

为获得最佳铝热焊接工艺参数,对拉伸试件进行了正交试验和二次通用旋转组合试验,研究预热温度、加压时间和预留焊缝3因素对接头强度的影响,进而寻求一组使焊接接头强韧性最高的焊接工艺参数组合。利用电子显微镜等对试件拉伸断口进行了分析,通过对比2种开始加压时间下试件的显微组织和性能,研究了这2种方法对接头强韧性的影响。结果表明:采用设计的铝热焊接试验装置和优化出的随焊加压致密化工艺参数,可使焊接接头获得大变形组织,从而获得高的强度和韧性。该项研究可为提高铝热焊接质量提供基础数据。