Optimal (τ, T) opportunistic maintenance of a k‐out‐of‐n:G system with imperfect PM and partial failure

The opportunistic maintenance of a k‐out‐of‐n:G system with imperfect preventive maintenance (PM) is studied in this paper, where partial failure is allowed. In many applications, the optimal maintenance actions for one component often depend on the states of the other components and system reliability requirements. Two new (τ, T) opportunistic maintenance models with the consideration of reliability requirements are proposed. In these two models, only minimal repairs are performed on failed components before time τ and the corrective maintenance (CM) of all failed components are combined with PM of all functioning but deteriorated components after τ; if the system survives to time T without perfect maintenance, it will be subject to PM at time T. Considering maintenance time, asymptotic system cost rate and availability are derived. The results obtained generalize and unify some previous research in this area. Application to aircraft engine maintenance is presented. © 2000 John Wiley & Sons;, Inc. Naval Research Logistics 47: 223–239, 2000     

Optimal policies for M/M/m queue with two different kinds of (N,T)‐policies

In this paper, two different kinds of (N, T)‐policies for an M/M/m queueing system are studied. The system operates only intermittently and is shut down when no customers are present any more. A fixed setup cost of K > 0 is incurred each time the system is reopened. Also, a holding cost of h > 0 per unit time is incurred for each customer present. The two (N, T)‐policies studied for this queueing system with cost structures are as follows: (1) The system is reactivated as soon as N customers are present or the waiting time of the leading customer reaches a predefined time T, and (2) the system is reactivated as soon as N customers are present or the time units after the end of the last busy period reaches a predefined time T. The equations satisfied by the optimal policy (N*, T*) for minimizing the long‐run average cost per unit time in both cases are obtained. Particularly, we obtain the explicit optimal joint policy (N*, T*) and optimal objective value for the case of a single server, the explicit optimal policy N* and optimal objective value for the case of multiple servers when only predefined customers number N is measured, and the explicit optimal policy T* and optimal objective value for the case of multiple servers when only predefined time units T is measured, respectively. These results partly extend (1) the classic N or T policy to a more practical (N, T)‐policy and (2) the conclusions obtained for single server system to a system consisting of m (m ≥ 1) servers. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 240–258, 2000     

树状军事通信网中的文件传输优化算法

针对树状军事通信网中的文件传输优化问题,提出了一种有效的寻找最优的树图边着色算法,该算法保证了边着色后的树图中"延迟损耗"总和最小,并由求取最小"延迟损耗"的反向推导过程得到最优的树状通信网文件传输方案.算法的计算复杂度是,其中为顶点数,为树的最大度.     

武器系统采购费与维修费权衡的依据分析

根据武器系统寿命周期费用的理论和方法,建立了系统的费用模型,依据数学分析和优化理论,在已知可用武器系统目标数的前提下,建立了费用优化条件,确定了采购费与维修费的比例限值,用以确定武器系统采购费和维修费的最优比例,从而对系统方案确定的权衡分析提供量化依据.     

装甲车辆动力传动系统整体性工程初探

全面考虑装甲车辆动力传动系统论证、研制、生产及使用等方面的因素,从整体、系统和全局的观点出发,论述了装甲车辆动力传动系统的整体式设计、一体化控制、性能综合评价和寿命周期费用分析.从而把装甲车辆动力传动系统的论证、研制、生产及使用看作一个整体性工程来考虑,克服了以往设计和使用中重点突出某一过程或部件,而忽略相互匹配和顾此失彼的问题,为在现有技术基础上进一步提高装甲车辆的机动性能,提供了一种新的研究思路.     

A Fuzzy Cluster and Retinex Theory-based Variation Model for Inhomogenous Image Segmentation

A variational inhomogeneous image segmentation model based on fuzzy membership functions and Retinex theory is proposed by introducing the fuzzy membership function.The existence of the solution of the proposed model is proved theoretically.A valid algorithm is designed to make numerical solution of the model under the framework of alternating minimization.The last experimental results show that the model can make segmentation of the real image with intensity inhomogeneity effectively.     

可拓工程方法在效能-费用权衡中的应用

介绍可拓学及物元理论,提出用可拓工程方法对武器装备效能-费用进行权衡分析。建立了装备效费权衡分析的高阶复合物元模型,对初始效费方案进行了延拓,提出可拓特征集的概念。在此基础上,对效能-费用方案进行可拓聚类分析。     

具有热阻、热漏和内不可逆性的联合卡诺热机生态学优化

用有限时间热力学的方法分析具有热阻、热漏、内不可逆性的定常流联合卡诺型热机循环.导出了在傅立叶导热定律下联合循环功率、效率和生态学指标的性能,并进行优化;得到功率、效率和生态学指标之间的优化关系,并由数值计算分析了功率、效率和循环熵产率之间的关系.所得的结果表明,最大生态学指标下的效率十分接近于联合循环可以达到的最大效率;相应的熵产率也要低于以输出功率为优化目标时的熵产率.     

THE EFFECTS OF THE WORLD DEFENSE INDUSTRY AND US MILITARY AID TO ISRAEL ON THE ISRAELI DEFENSE INDUSTRY: A DIFFERENTIATED PRODUCTS MODEL

This paper models the interactions between the defense industry market structure and the defense needs of Israel, the USA and Western Europe, which produce several heterogeneous defense goods. The model specifies that the defense industries of the US and Europe are ‘large’ while that of Israel is ‘small’. The US military aid to Israel is also an integral part of the model. The results show that net defense costs of Israel are minimal when the number of its defense firms is one. The model predicts that an increase in US military aid reduces Israel’s government expenditure, its defense industry’s profits and its net defense costs.     

The structure of the defense industry and the security needs of the country: a differentiated products model

This paper models the interactions between the defense needs of the USA and Western Europe, which produce several heterogeneous defense goods, and the defense industry market structure. The results show that net defense costs of the USA and Europe are lower when the number of defense firms in each arms‐producing country is small and when the world prices of the defense goods are high. The model predicts that the increase in world prices will crowd‐out countries in the developing world from the market for modern weapon systems and may force them to develop and use ‘cheap and dirty’ weapon systems.