利用矩阵求极大相容类的一种方法

寻找相容关系的极大相容类和简单图的极大完全子图,在解决二元关系与数据挖掘和管理决策中的具体问题时有重要作用。利用相容关系的极大相容类与简单图的极大完全子图之间的对应关系,对极大完全子图的路径长度进行分析,得到了关于极大完全子图路径长度的一个定理。并根据该定理构造了一个用矩阵的路径长度搜索简单图的极大完全子图的方法,进而利用该方法找出了对应相容关系的极大相容类。     

Scheduling policies for an antiterrorist surveillance system

This article concerns scheduling policies in a surveillance system aimed at detecting a terrorist attack in time. Terrorist suspects arriving at a public area are subject to continuous monitoring, while a surveillance team takes their biometric signatures and compares them with records stored in a terrorist database. Because the surveillance team can screen only one terrorist suspect at a time, the team faces a dynamic scheduling problem among the suspects. We build a model consisting of an M/G/1 queue with two types of customers—red and white—to study this problem. Both types of customers are impatient but the reneging time distributions are different. The server only receives a reward by serving a red customer and can use the time a customer has spent in the queue to deduce its likely type. In a few special cases, a simple service rule—such as first‐come‐first‐serve—is optimal. We explain why the problem is in general difficult and we develop a heuristic policy motivated by the fact that terrorist attacks tend to be rare events. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

On the exponentially weighted moving variance

MacGregor and Harris (J Quality Technol 25 (1993) 106–118) proposed the exponentially weighted mean squared deviation (EWMS) and the exponentially weighted moving variance (EWMV) charts as ways of monitoring process variability. These two charts are particularly useful for individual observations where no estimate of variability is available from replicates. However, the control charts derived by using the approximate distributions of the EWMS and EWMV statistics are difficult to interpret in terms of the average run length (ARL). Furthermore, both control charting schemes are biased procedures. In this article, we propose two new control charts by applying a normal approximation to the distributions of the logarithms of the weighted sum of chi squared random variables, which are respectively functions of the EWMS and EWMV statistics. These new control charts are easy to interpret in terms of the ARL. On the basis of the simulation studies, we demonstrate that the proposed charts are superior to the EWMS and EWMV charts and they both are nearly unbiased for the commonly used smoothing constants. We also compare the performance of the proposed charts with that of the change point (CP) CUSUM chart of Acosta‐Mejia (1995). The design of the proposed control charts is discussed. An example is also given to illustrate the applicability of the proposed control charts. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

Steady‐state diffusion approximations for discrete‐time queue in hospital inpatient flow management

In this article, we analyze a discrete‐time queue that is motivated from studying hospital inpatient flow management, where the customer count process captures the midnight inpatient census. The stationary distribution of the customer count has no explicit form and is difficult to compute in certain parameter regimes. Using the Stein's method framework, we identify a continuous random variable to approximate the steady‐state customer count. The continuous random variable corresponds to the stationary distribution of a diffusion process with state‐dependent diffusion coefficients. We characterize the error bounds of this approximation under a variety of system load conditions—from lightly loaded to heavily loaded. We also identify the critical role that the service rate plays in the convergence rate of the error bounds. We perform extensive numerical experiments to support the theoretical findings and to demonstrate the approximation quality. In particular, we show that our approximation performs better than those based on constant diffusion coefficients when the number of servers is small, which is relevant to decision making in a single hospital ward.     

基于排队论模型的轮询协议数据链系统时延分析

基于数据链系统的作战方式已经成为了现代化战场的主流,战争中战机稍纵即逝,因此,分析数据链系统的信息传输时延特性意义重大。针对数据链系统信息传输时延问题,分析了数据链系统传输命令消息,目标消息以及中继消息的一般过程,并给出了排队论模型。根据排队论的相关知识得到了轮询协议数据链传输时延的公式,最后利用仿真软件进行了分析研究。     

基于消防响应时间满意度的消防站布局优化研究

消防站布局是否合理是及时扑灭火灾的关键,当前城市消防站规划方法主观性较大,缺乏量化数据支持,研究科学合理的城市消防站布局优化方法,具有十分重要的意义。在吸收前人研究的基础上,运用区域火灾风险评估、ARCGIS、遗传算法等,在构建消防响应时间满意度函数的基础上,构建了基于消防响应时间满意度的消防站布局优化选址方法。该方法从消防需求角度对研究区域的消防站布局进行了规划,达到用最少的消防站覆盖全部的消防需求点,以实现消防资源的最优化配置。     

基于排队论的油料供给最优化分析

通过有限源排队系统的理论,分析油料供给工作中在满足一定的可靠性要求下的最优设计与最优分配问题,同时结合计算机技术,提出了求数值解的方法。     

利用排队模型优化保障设备数量

就如何将排队论法应用于确定保障设备数量的方法进行了分析和研究,得出一种可行的确定保障设备数量的方法,对研制过程中科学地规划保障设备的数量提供了借鉴,对提高装备的保障力和战斗力以及降低全寿命周期费用具有重要意义.     

混合排队规则的战术装备维修保障系统分析

首先将战术装备维修保障过程描述为M/M/c/k混合规则的排队过程,其损坏装备到达服从相互独立的泊松分布,维修时间服从相互独立的指数分布。同时考虑系统的到达率和维修率随系统中装备数量的变化,重要战损装备等待维修时的不耐烦性以及重要装备对一般装备的强占性优先权情况,结合战术装备维修保障系统的结构和规模,建立战术装备维修保障M/M/3/12排队模型。列出模型的平衡方程,采用矩阵的分析方法得到重要装备和一般装备的稳态分布表达式,并以队长为指标进行了系统性能的计算。     

多体存贮器有效频带分析

本文以排队论为工具建立了紧耦合多处理机系统存贮器的排队模型。通过对存贮体忙期的分析,得出了存贮器有效频带的解析表达式,研究了在保证存贮器有效频带最大的情况下,处理机的访存请求率λ、存贮体的服务率μ和存贮体数m 三者之间的关系。