Minimal LST representations of MAP(n)s: Moment fittings and queueing approximations

A Markovian arrival process of order n, MAP(n), is typically described by two n × n transition rate matrices in terms of rate parameters. While it is straightforward and intuitive, the Markovian representation is redundant since the minimal number of parameters is n² for non‐redundant MAP(n). It is well known that the redundancy complicates exact moment fittings. In this article, we present a minimal and unique Laplace‐Stieltjes transform (LST) representations for MAP(n)s. Even though the LST coefficients vector itself is not a minimal representation, we show that the joint LST of stationary intervals can be represented with the minimum number of parameters. We also propose another minimal representation for MAP(3)s based on coefficients of the characteristic polynomial equations of the two transition rate matrices. An exact moment fitting procedure is presented for MAP(3)s based on two proposed minimal representations. We also discuss how MAP(3)/G/1 departure process can be approximated as a MAP(3). A simple tandem queueing network example is presented to show that the MAP(3) performs better than the MAP(2) in queueing approximations especially under moderate traffic intensities. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 549–561, 2016     

用于混合动力汽车的球形发动机热力学过程分析

作为混合动力汽车增程系统的一种新型动力源,球形发动机有着功率密度高,结构紧凑等优点。在介绍球形发动机工作原理及基本结构的基础之上,研究了发动机气缸容积变化规律,分析发动机燃烧过程,建立了发动机热力学理论模型。利用FLUENT开展了仿真研究,验证了模型的正确性,进而对于发动机燃油喷射过程进行了分析。结果表明：计算得到的气缸内部温度与压力曲线与仿真得到的结果基本一致,验证了理论模型的正确性。在燃油喷射的过程中,可能会出现涡团状的燃油喷射轨迹,使得局部富油发生,燃烧性能变差。     

基于权重的AHP判断矩阵一致性调整方法

传统的判断矩阵调整方法计算得到的权重不能最大限度地保留原始判断矩阵的信息。为此,提出一种基于权重的判断矩阵调整方法。该方法根据权重的性质,构造完全一致矩阵,利用AdaGrad最速下降法对矩阵进行拟合,使该矩阵相对于原始判断矩阵的总改变量最小,以其对应的权重作为矩阵的计算结果。数值计算结果表明,该方法相比于其他方法,权重对原始判断信息的保留度更高,且不需要反复进行矩阵一致性检验。     

A bivariate optimal replacement policy for a cold standby repairable system with repair priority

In this article, an optimal replacement policy for a cold standby repairable system consisting of two dissimilar components with repair priority is studied. Assume that both Components 1 and 2, after repair, are not as good as new, and the main component (Component 1) has repair priority. Both the sequence of working times and that of the components'repair times are generated by geometric processes. We consider a bivariate replacement policy (T,N) in which the system is replaced when either cumulative working time of Component 1 reaches T, or the number of failures of Component 1 reaches N, whichever occurs first. The problem is to determine the optimal replacement policy (T,N)* such that the long run average loss per unit time (or simply the average loss rate) of the system is minimized. An explicit expression of this rate is derived, and then optimal policy (T,N)* can be numerically determined through a two‐dimensional‐search procedure. A numerical example is given to illustrate the model's applicability and procedure, and to illustrate some properties of the optimal solution. We also show that if replacements are made solely on the basis of the number of failures N, or solely on the basis of the cumulative working time T, the former class of policies performs better than the latter, albeit only under some mild conditions. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

Stability of information‐sharing alliances in a three‐level supply chain

In their recent article, Leng and Parlar (L&P) (2009) analyze information‐sharing alliances in a three‐level supply chain (consisting of a manufacturer, a distributor, and a retailer) that faces a nonstationary end demand. Supply chain members can share demand information, which reduces information distortion and thus decreases their inventory holding and shortage costs. We expand the results from L&P by considering dynamic (farsighted) stability concepts. We use two different allocation rules and show that under some reasonable assumptions there should always be some information sharing in this supply chain. We also identify conditions under which the retailer in a stable outcome shares his demand information with the distributor, with the manufacturer, or with both remaining supply chain members. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

Asymptotic properties of imperfect repair models and estimation of repair efficiency

The aim of this articles is to study the asymptotic behavior of two imperfect repair models, called Arithmetic Reduction of Intensity and Arithmetic Reduction of Age models. These models have been proposed by Doyen and Gaudoin (Reliab Eng Syst Safe 84 (2004) 45–56) and include many usual virtual age models. First, it is proved that the failure intensity of these models is asymptotically almost surely equivalent to a deterministic increasing function with a cumulative error proportional to a logarithm. Second, the almost sure convergence and asymptotic normality of several estimators of repair efficiency are derived, when the wear‐out process without repair is known. Finally, the coverage rate of the asymptotic confidence intervals issued from those estimators is empirically studied. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010     

基于视频叠加的心理暗示信息生成和影响机制研究

针对心理战中潜移默化影响对象国民众的需求,提出了基于视频叠加的心理暗示(PSBOVS)的构想,从心理依据和视频基础两个方面研究了视频叠加暗示信息的生成和影响机制。给出了基于视频叠加的心理暗示效应过程模型,并结合心理因素对信息生成进行了视频建模和参数分析,从暗示信息被接收、注意、理解和接受的角度,对信息内容和形式的确定进行了论述。为暗示信息有效编码进而有效影响受众心理提供了理论依据和决策支持。     

地磁匹配算法研究框架和组合匹配策略

以空中无人平台为背景,研究了地磁辅助惯性导航系统。分析了地磁匹配的特点,给出了一维匹配的概念。从特征空间、相似性度量、搜索空间、搜索策略等四个方面对一维匹配进行了分析,建立了一个地磁匹配方法研究的框架。通过简化惯导解算过程,将一维地磁匹配归结为一个带补偿过程的仿射变换,并提出了一种基于等值线约束的组合匹配算法。该算法兼顾了匹配的全局搜索能力和局部定位能力,能在飞行过程中在线进行。在仿真和车载实验中,对算法的匹配精度、速度、适应性进行了分析和验证,检验了算法的有效性和可行性。     

基于SOA的军事信息系统综合集成研究

通过分析目前军事信息系统综合集成中存在的问题,阐述面向服务的体系架构SOA(Service-Oriented Architecture)的概念、基本工作原理,比较SOA相对于传统集成方案的不同之处。提出了基于SOA的军事信息系统集成体系结构及实施集成的基本步骤,说明了基于SOA的军事信息系统集成能够较好利用已有的信息系统的优势。     

一种基于协调理论的军事决策过程建模方法

在分析协调理论应用的基础上,针对军事决策过程的建模,基于UML2.0的用例图,提出了基于协调理论的军事决策过程建模方法。应用该建模方法,有利于分析军事决策过程中的核心任务活动及其相关依赖,为指挥员实施平行决策,并发地制订和确定作战方案(Course of Action)提供依据,从而提高军事决策过程的适应性。