Optimal allocation of minimal repairs in parallel and series systems

In reliability engineering, the concept of minimal repair describes that the repair brings the failed unit (eg, system or component) to the situation which is same as it was just before the failure. With the help of the well‐known Gamma‐Poisson relationship, this paper investigates optimal allocation strategies of minimal repairs for parallel and series systems through implementing stochastic comparisons of various allocation policies in terms of the hazard rate, the reversed hazard rate, and the likelihood ratio orderings. Numerical examples are presented to illustrate these findings as well. These results not only strengthen and generalize some known ones in the seminal work of Shaked and Shanthikumar, but also solve the open problems proposed by Chahkandi et al.'s study and Arriaza et al.'s study.     

Single‐machine scheduling with deadlines to minimize the total weighted late work

We consider scheduling a set of jobs with deadlines to minimize the total weighted late work on a single machine, where the late work of a job is the amount of processing of the job that is scheduled after its due date and before its deadline. This is the first study on scheduling with the late work criterion under the deadline restriction. In this paper, we show that (i) the problem is unary NP‐hard even if all the jobs have a unit weight, (ii) the problem is binary NP‐hard and admits a pseudo‐polynomial‐time algorithm and a fully polynomial‐time approximation scheme if all the jobs have a common due date, and (iii) some special cases of the problem are polynomially solvable.     

The building evacuation problem with shared information

In this article, the Building Evacuation Problem with Shared Information (BEPSI) is formulated as a mixed integer linear program, where the objective is to determine the set of routes along which to send evacuees (supply) from multiple locations throughout a building (sources) to the exits (sinks) such that the total time until all evacuees reach the exits is minimized. The formulation explicitly incorporates the constraints of shared information in providing online instructions to evacuees, ensuring that evacuees departing from an intermediate or source location at a mutual point in time receive common instructions. Arc travel time and capacity, as well as supply at the nodes, are permitted to vary with time and capacity is assumed to be recaptured over time. The BEPSI is shown to be NP‐hard. An exact technique based on Benders decomposition is proposed for its solution. Computational results from numerical experiments on a real‐world network representing a four‐story building are given. Results of experiments employing Benders cuts generated in solving a given problem instance as initial cuts in addressing an updated problem instance are also provided. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Dynamic inventory management with cash flow constraints

In this article, we consider a classic dynamic inventory control problem of a self‐financing retailer who periodically replenishes its stock from a supplier and sells it to the market. The replenishment decisions of the retailer are constrained by cash flow, which is updated periodically following purchasing and sales in each period. Excess demand in each period is lost when insufficient inventory is in stock. The retailer's objective is to maximize its expected terminal wealth at the end of the planning horizon. We characterize the optimal inventory control policy and present a simple algorithm for computing the optimal policies for each period. Conditions are identified under which the optimal control policies are identical across periods. We also present comparative statics results on the optimal control policy. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2008     

多架战机协同作战信息融合系统的设计

简要介绍了CEC的发展背景,给出了一种基于CEC技术的多架战机协同作战多传感器信息融合系统的设计,较系统地阐述了信息融合硬件模型结构及功能,并分析了多机协同作战面临的主要问题,多机协同作战的关键技术以及将来可能的应用,指出了多机协同作战的研究方向,为空军多机协同作战的进一步深入研究提供参考.     

多机CEC系统的传感器联网核心技术

对协同传感器联网的基本概念、原理以及重要性进行了阐述,提出了一种分布式无线传感器网络体系结构,对协同传感器管理的基本方法进行了分析与综合,指出了协同传感器方法发展的基本特征和进一步需要研究的问题.CEC传感器网络集成了无线网络通信、嵌入式处理和传感器技术等多项技术,分析了传感器网络的自组织、自适应的特点与需求,并在此基础上就若干关键性技术问题进行了探讨.     

风场的科学计算可视化在导弹射击中的应用

在导弹射击时,消除风会对导弹飞行造成不利的影响,因此基于可视化分析的研究模型、流程等,利用科学计算方法直观分析优点对风的大小和方向进行分析,并采用开放图形接口对实验风场数据进行了三维图形绘制以提高导弹打击目标的精度,对实际中导弹的风场阻力研究有一定的指导意义.     

A decision support system for the procurement of military equipment

The use of life-cycle costs in procurement is limited by the accuracy of cost estimates and assessments of availability risks under the conditions generating costs. Critical to these problems are the needs and responses of equipment to maintenance and repair. Using transition probabilities to define the relationships between serviceability and maintenance and repairs, this article develops a comprehensive decision support system for military procurement. It uses a dynamic programming model to determine the least-cost set of maintenance and repair decisions, where adjustments are included for warranty conditions, time value of money, the opportunity costs of equipment failure, and the end-of-cycle salvage values or disposal costs. The system allows users to define working and failed states, create their own rules or indicators of availability from estimates of state probabilities and establish thresholds of risk acceptability.     

改进型自适应推广卡尔曼滤波器的应用

针对在被动方式下进行水下目标跟踪容易导致滤波发散和收敛精度不高的问题,介绍了一种改进的自适应推广卡尔曼滤波算法。它能够在线估计虚拟观测噪声的统计特性,从而克服了观测模型线性化误差带来的不良影响。同时,通过引入修正增益函数,克服了由于观测噪声的统计特性不能精确已知而导致的滤波不稳定问题。仿真结果表明,不管是滤波精度还是收敛速度,都优于原来的自适应推广卡尔曼滤波算法     

一种基于模糊理论和神经网络的水雷状态识别方法

介绍了一种基于模糊集合和神经网络的水雷状态识别方法 .该方法根据实际情况 ,将模糊集合和径向基函数神经网络结合起来 ,用于水雷状态的识别 .仿真结果表明 ,这种识别方法性能稳定 ,且有很高的识别精度 .