Maintaining systems with heterogeneous spare parts

We consider the problem of optimally maintaining a stochastically degrading, single‐unit system using heterogeneous spares of varying quality. The system's failures are unannounced; therefore, it is inspected periodically to determine its status (functioning or failed). The system continues in operation until it is either preventively or correctively maintained. The available maintenance options include perfect repair, which restores the system to an as‐good‐as‐new condition, and replacement with a randomly selected unit from the supply of heterogeneous spares. The objective is to minimize the total expected discounted maintenance costs over an infinite time horizon. We formulate the problem using a mixed observability Markov decision process (MOMDP) model in which the system's age is observable but its quality must be inferred. We show, under suitable conditions, the monotonicity of the optimal value function in the belief about the system quality and establish conditions under which finite preventive maintenance thresholds exist. A detailed computational study reveals that the optimal policy encourages exploration when the system's quality is uncertain; the policy is more exploitive when the quality is highly certain. The study also demonstrates that substantial cost savings are achieved by utilizing our MOMDP‐based method as compared to more naïve methods of accounting for heterogeneous spares.     

Can Limited Intervention Work? Lessons from Britain’s Success Story in Sierra Leone

ABSTRACT

Following frustrating campaigns in Iraq and Afghanistan, Western interventions are becoming more limited, with troops being deployed for short bursts and residual peace-building tasks being left to others. Although this approach limits exposure for the intervening government, it struggles to achieve meaningful political change. Examining the comparatively successful British intervention in Sierra Leone (2000–02), this article identifies the conditions for effectiveness in these campaigns. It challenges the historiography of the case by framing armed confrontations and raids as enablers of politics rather than ends in themselves; indeed, in both the conduct and study of intervention, politics must reign supreme.     

The impact of manufacturer rebates on supply chain profits

Manufacturer rebates are commonly used as price discount tools for attracting end customers. In this study, we consider a two‐stage supply chain with a manufacturer and a retailer, where a single seasonal product faces uncertain and price‐sensitive demand. We characterize the impact of a manufacturer rebate on the expected profits of both the manufacturer and the retailer. We show that unless all of the customers claim the rebate, the rebate always benefits the manufacturer. Our results thus imply that “mail‐in rebates,” where some customers end up not claiming the rebate, particularly when the size of the rebate is relatively small, always benefit the manufacturer. On the other hand, an “instant rebate,” such as the one offered in the automotive industry where every customer redeems the rebate on the spot when he/she purchases a car, does not necessarily benefit the manufacturer. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

学习《关于正确处理人民内部矛盾的问题》构建和谐军营

《关于正确处理人民内部矛盾的问题》揭示了社会发展进程中的共性规律,不仅具有深远的理论贡献和方法论意义,而且具有重大的实践指导作用。本文围绕构建和谐军营的主题,从与时俱进、宽容审慎;以人为本、关注个性;民主科学、公平公正等维度着手,探析其理论的实践意义,以飨读者。     

领导干部要努力提高处置突发事件的能力

领导干部要提高处置突发事件的能力,必须充分认清正确处置突发事件的重要性紧迫性;科学把握正确应对突发事件的一些重点环节;努力增强正确应对突发事件的能力素质.     

Effects of cueing in cooperative search

We consider the effects of cueing in a cooperative search mission that involves several autonomous agents. Two scenarios are discussed: one in which the search is conducted by a number of identical search‐and‐engage vehicles and one where these vehicles are assisted by a search‐only (reconnaissance) asset. The cooperation between the autonomous agents is facilitated via cueing, i.e., the information transmitted to the agents by a searcher that has just detected a target. The effect of cueing on the target detection probability is derived from first principles using a Markov chain analysis. In particular, it is demonstrated that the benefit of cueing on the system's effectiveness is bounded. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

美陆、海、空、天2010年及以后发展构想综述

对美陆、海、空三军２０１０年规划、２０１０年联合构想、美航天２０２０年规划、海军２０３５年、空军２０２５年进行了全面总结,系统归纳了美军新的能力和作战概念,对了解和借鉴美军事技术革命以来的成果和规划我军２０１０年及以后发展规划有重要参考价值。     

观瞄仪器微控MTF测量

为了全面客观地评价观瞄仪器成像质量,介绍采用光电探测原理和微机控制的信息处理技术,对观瞄仪器进行调制传递函数(MTF)测量的方法;用该方法全面评价观瞄仪器质量,具有操作简单,速度快,精度高,测量周期短的特点,适用于不同场合对各类观瞄仪器进行MTF(f)测量。     

Cyclic best first search: Using contours to guide branch‐and‐bound algorithms

The cyclic best‐first search (CBFS) strategy is a recent search strategy that has been successfully applied to branch‐and‐bound algorithms in a number of different settings. CBFS is a modification of best‐first search (BFS) that places search tree subproblems into contours which are collections of subproblems grouped in some way, and repeatedly cycles through all non‐empty contours, selecting one subproblem to explore from each. In this article, the theoretical properties of CBFS are analyzed for the first time. CBFS is proved to be a generalization of all other search strategies by using a contour definition that explores the same sequence of subproblems as any other search strategy. Further, a bound is proved between the number of subproblems explored by BFS and the number of children generated by CBFS, given a fixed branching strategy and set of pruning rules. Finally, a discussion of heuristic contour‐labeling functions is provided, and proof‐of‐concept computational results for mixed‐integer programming problems from the MIPLIB 2010 database are shown. © 2017 Wiley Periodicals, Inc. Naval Research Logistics, 64: 64–82, 2017