Application of Markov renewal theory and semi-Markov decision processes in maintenance modeling and optimization of multi-unit systems

In this paper, a condition-based maintenance model for a multi-unit production system is proposed and analyzed using Markov renewal theory. The units of the system are subject to gradual deterioration, and the gradual deterioration process of each unit is described by a three-state continuous time homogeneous Markov chain with two working states and a failure state. The production rate of the system is influenced by the deterioration process and the demand is constant. The states of the units are observable through regular inspections and the decision to perform maintenance depends on the number of units in each state. The objective is to obtain the steady-state characteristics and the formula for the long-run average cost for the controlled system. The optimal policy is obtained using a dynamic programming algorithm. The result is validated using a semi-Markov decision process formulation and the policy iteration algorithm. Moreover, an analytical expression is obtained for the calculation of the mean time to initiate maintenance using the first passage time theory.     

On efficient algorithms for finding efficient salvo policies

We consider the salvo policy problem, in which there are k moments, called salvos, at which we can fire multiple missiles simultaneously at an incoming object. Each salvo is characterized by a probability p_i: the hit probability of a single missile. After each salvo, we can assess whether the incoming object is still active. If it is, we fire the missiles assigned to the next salvo. In the salvo policy problem, the goal is to assign at most n missiles to salvos in order to minimize the expected number of missiles used. We consider three problem versions. In Gould's version, we have to assign all n missiles to salvos. In the Big Bomb version, a cost of B is incurred when all salvo's are unsuccessful. Finally, we consider the Quota version in which the kill probability should exceed some quota Q. We discuss the computational complexity and the approximability of these problem versions. In particular, we show that Gould's version and the Big Bomb version admit pseudopolynomial time exact algorithms and fully polynomial time approximation schemes. We also present an iterative approximation algorithm for the Quota version, and show that a related problem is NP-complete.     

基于循环子空间理论的线性系统测试矩阵优化

研究了线性定常系统在循环指数大于1(即其约当标准形不同的约当块有重根)的情况下测试矩阵的优化方法.以循环子空间相关定理的证明为基础,根据根向量链的相关特性,得到了测试向量的线性和与系统观测性的直接关系,给出了在保证系统可观测性的同时,使得测试代价最小的测试矩阵优化方法.算例表明,提出的方法简单直观,对配置测试向量具有良好的工程价值.     

关于独立学院教学体制的构建

独立学院作为一种新型的办学模式，是高教改革的战略抉择，对我国高等教育向“大众化教育”转变具有重要的意义。构建合理的独立学院教学体制是实现人才培养的关键。对此，独立学院必须以培养应用型专门人才为目标，以市场为导向，科学确定学生的知识结构和能力体系，构建合理的人才培养模式；应根据独立学院的特点，以教学运行管理为重点，加强教学管理的规范化建设，构建合理的教学管理机制；以提高教学质量为目标，构建合理的教学质量监控与保障体系；充分运用独立学院灵活的办学机制，构建一支由母体高校教师、专任教师和兼职教师三部分组成的，适应独立学院教学工作需要的教师队伍。     

一种改进的事件驱动系统框架

在给出事件驱动系统安全漏洞的基础上,指出了产生漏洞的根本原因是:系统忽视了输入系统的事件序列之间存在的相关性;系统无条件信任任何事件源产生的事件.针对这两个原因,相应提出了事件序列形式安全分析模型及基于事件源的可信度评估模型,依据这两个模型,构建了一种改进的事件驱动系统框架.     

别斯兰事件后俄罗斯反恐机制的重建

随着苏联的解体,本来著称于世的强效反恐机制一夜之间分崩离析,反恐部门权责不清,协调不畅,反恐不力,恐怖势力乘虚而入,俄罗斯频频处于恐怖事件威胁之下。别斯兰事件给俄罗斯敲响了警钟。通过实施一系列有效措施,俄罗斯重建反恐机制,并取得明显效果。     

基于灰色系统理论的目标方位估算及应用

针对潜艇作战过程中依据目标方位变化判断战场态势的军事需求,根据灰色系统理论,以实测目标方位序列为原始数据,建立GM(1,1)模型,深入挖掘其内在规律性,对目标方位序列的变化趋势进行科学分析,并估算未来时刻目标方位,用于战术态势判断、检验目标运动要素解算和战术绘算的准确性,以及干预目标运动要素解算,以期望利用有限的数据,获得最大限度的信息,为潜艇指挥员提供决策支持。     

从孙子“全胜”思想看执勤体系能力建设

在现代条件下，从孙子“全胜”思想来看执勤体系能力建设，需要持续完善信息系统，优化平台建设和落实制度建设，切实提高执勤体系的“有效防范”和“高效处置”能力，继而确保执勤目标的绝对安全。     

中国传统战争哲学理念的近代嬗变

近代以来，在西方列强坚船利炮的重创之下，中华民族在军事上接连失败。在严酷的现实面前，中华民族流传两千多年的传统战争哲学理念，受到了前所未有的挑战。在近代战争的冲击下，中国传统战争哲学理念开始了缓慢的嬗变历程。主要表现为三点：“避战求和”理念的破产与激变；“义战必胜”理念的质疑与超越；“道器合一”理念的背离与回归。     

柴油机排气集水箱降温特性及其影响因素

针对常规潜艇柴油机排气系统集水箱,分别建立了不同管束结构集水箱的数值模型,并得到了各自内部流场及温度场的分布;分析了细管长度、细管转折形式和布置形式对其冷却降温性能和阻力特性的影响。结果表明:内层管长L1大于外层管长L2的结构比等管长的结构排气阻力小,降温冷却效果更明显;细管末端的弯管与折管相比,排气阻力小,降温性能更优越。