Generalizing the survival signature to unrepairable homogeneous multi‐state systems

The notion of signature has been widely applied for the reliability evaluation of technical systems that consist of binary components. Multi‐state system modeling is also widely used for representing real life engineering systems whose components can have different performance levels. In this article, the concept of survival signature is generalized to a certain class of unrepairable homogeneous multi‐state systems with multi‐state components. With such a generalization, a representation for the survival function of the time spent by a system in a specific state or above is obtained. The findings of the article are illustrated for multi‐state consecutive‐k‐out‐of‐n system which perform its task at three different performance levels. The generalization of the concept of survival signature to a multi‐state system with multiple types of components is also presented. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 593–599, 2017     

The probability of the existence of a feasible flow in a stochastic transportation network

Stochastic transportation networks arise in various real world applications, for which the probability of the existence of a feasible flow is regarded as an important performance measure. Although the necessary and sufficient condition for the existence of a feasible flow represented by an exponential number of inequalities is a well‐known result in the literature, the computation of the probability of all such inequalities being satisfied jointly is a daunting challenge. The state‐of‐the‐art approach of Prékopa and Boros, Operat Res 39 (1991) 119–129 approximates this probability by giving its lower and upper bounds using a two‐part procedure. The first part eliminates all redundant inequalities and the second gives the lower and upper bounds of the probability by solving two well‐defined linear programs with the inputs obtained from the first part. Unfortunately, the first part may still leave many non‐redundant inequalities. In this case, it would be very time consuming to compute the inputs for the second part even for small‐sized networks. In this paper, we first present a model that can be used to eliminate all redundant inequalities and give the corresponding computational results for the same numerical examples used in Prékopa and Boros, Operat Res 39 (1991) 119–129. We also show how to improve the lower and upper bounds of the probability using the multitree and hypermultitree, respectively. Furthermore, we propose an exact solution approach based on the state space decomposition to compute the probability. We derive a feasible state from a state space and then decompose the space into several disjoint subspaces iteratively. The probability is equal to the sum of the probabilities in these subspaces. We use the 8‐node and 15‐node network examples in Prékopa and Boros, Operat Res 39 (1991) 119–129 and the Sioux‐Falls network with 24 nodes to show that the space decomposition algorithm can obtain the exact probability of these classical examples efficiently. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 479–491, 2016     

基于计算机三维建模技术的两栖车辆静水性能计算

为了解决传统静水性能计算中倾斜浮态下浮心计算困难的问题,建立了两栖车辆的三维实体模型,研究了任意浮态下浮心的计算方法。在此基础上,求解了两栖车辆在静水平衡时的浮态,并利用SolidWorks提供的API函数进行二次开发,实现了计算的自动化。经实例验证表明,该算法准确、快速。     

Lipschitz非线性系统状态观测器设计新方法

针对Lipschitz非线性系统状态观测器,提出了一种以极小化条件数为目标准则的新的设计方法。运用梯度下降法和Slyvester方程,计算极小化条件数,优化增益矩阵和最大允许Lipschitz常数,完成观测器设计。通过同其它文献的算例比较,结果发现按文中方法设计的观测器具有迭代次数少、优化结果好的特点。     

基于观测器的某火控系统故障诊断方法

以某自行高炮火控系统为对象,研究了基于状态观测器的故障诊断方法,并作了仿真试验.通过状态观测器提取相对余差来检测和识别故障.试验结果表明,对于火控系统中可以建立数学模型的分系统或单体,基于观测器的故障诊断方法具有较好的诊断效果.该方法已成功应用于某高炮火控系统的综合检测与诊断设备中.     

基于有限状态机的作战实体模型行为规则可视化建模研究

为提升仿真模型开发效率,降低仿真模型的维护成本,本文从模型规则可视化建模需求入手,提出了基于有限状态机的实体模型行为规则形式化表达模型,并对基于有限状态机的模型规则可视化建模工具框架进行了设计,对模型规则可视化建模的工程实现进行了理论上的探索。     

考虑输入受限的高超声速飞行器预设性能控制

针对考虑输入幅值与速率受限的高超声速飞行器跟踪性能问题,提出基于受限指令滤波器的预设性能控制方案。为了提高系统瞬态和稳态性能,设计预设性能反演控制器,并通过设计新的性能函数使得跟踪误差超调量更小。引入指令滤波器来处理反演控制器设计中难以求导的问题。针对输入受限问题,构造一种受限指令滤波器来约束系统控制律,保证控制输入满足幅值和速率的限制要求,并进行相应的理论证明。另外,考虑系统参数不确定性与外界干扰,采用线性扩张状态观测器进行观测并补偿。基于Lyapunov稳定理论证明系统的所有跟踪误差最终一致有界。通过仿真验证该方法的有效性。     

授业、解惑、传道——古代文学史教学的三重境界

在高校古代文学史教学中教学效果和学生的学习效率因教师水平的不同存在较大差距,根据研究,发现可以将教学效果归结于教师的教学境界,借用韩愈《师说》中“师者,传道授业解惑也”的说法,教师的教学境界存在授业、解惑、传道三个层次,三个层次逐次递进,对教师的要求也是逐步提高。     

装备虚拟训练操作过程监控系统的设计

针对在面向操作训练的装备虚拟训练系统开发中遇到的对受训者操作监控的问题,为实现对装备操作过程的详尽描述和对受训者操作逻辑性的监控,提出了一种基于IDEF3的装备操作过程概念建模方法和基于有限状态机、浅层专家知识数据库的操作过程监控系统的设计方案。建立了监控系统的结构框架,并详细介绍了系统三个组成部分的设计方案：浅层专家知识数据库、操作过程状态机和通用操作监控引擎。基于此设计方案的操作过程监控系统已成功的应用于某装备虚拟训练平台,解决了对受训者的操作监控问题,提高了训练效果。     

基于操纵件状态时序变化的车辆换挡动作识别方法

为了解决驾驶训练中乘员操纵动作难以保留和再现,而无法进行深入分析的不足,提出了用操纵件位移数据记录乘员动作,用状态变化矩阵描述动作过程,用驾驶规则中规定的动作时序特征识别乘员特定操作动作等一系列新方法,实现了车辆驾驶动作的数字化记录、智能化识别和自动化评估。