Approximation algorithms for general one‐warehouse multi‐retailer systems

Logistical planning problems are complicated in practice because planners have to deal with the challenges of demand planning and supply replenishment, while taking into account the issues of (i) inventory perishability and storage charges, (ii) management of backlog and/or lost sales, and (iii) cost saving opportunities due to economies of scale in order replenishment and transportation. It is therefore not surprising that many logistical planning problems are computationally difficult, and finding a good solution to these problems necessitates the development of many ad hoc algorithmic procedures to address various features of the planning problems. In this article, we identify simple conditions and structural properties associated with these logistical planning problems in which the warehouse is managed as a cross‐docking facility. Despite the nonlinear cost structures in the problems, we show that a solution that is within ε‐optimality can be obtained by solving a related piece‐wise linear concave cost multi‐commodity network flow problem. An immediate consequence of this result is that certain classes of logistical planning problems can be approximated by a factor of (1 + ε) in polynomial time. This significantly improves upon the results found in literature for these classes of problems. We also show that the piece‐wise linear concave cost network flow problem can be approximated to within a logarithmic factor via a large scale linear programming relaxation. We use polymatroidal constraints to capture the piece‐wise concavity feature of the cost functions. This gives rise to a unified and generic LP‐based approach for a large class of complicated logistical planning problems. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

基于卡尔曼滤波的反舰导弹火控数据处理

在舰载反舰导弹火控系统的数据处理中,由于量测数据受到不同程度的噪声影响,不能将得到的数据直接参与导弹射击方程的运算,必须通过对观测设备提供的数据进行卡尔曼滤波处理,为了保证获取处理数据既具有较高的精度又具有较好的稳定性,还要具有较好的时效性,因此通过采用自适应卡尔曼滤波算法,极大地提高了系统数据处理的效果,获得了较理想的反舰导弹火控系统导弹射击参数.     

科学整合军地资源 推进国防后备力量建设创新发展

积极整合军地资源加强国防后备力量建设,是创新后备力量建设发展模式,提高后备力量建设使用效益的重要途径。当前,应以长效融合社会人力建设资源、积极聚合军地装备物资资源、有序衔接国家危机管理资源和科学统筹区位特色优势资源为突破,培育专业常态的国防后备力量组织结构基础,完善多边联供的国防后备力量行动保障体系,搭建双应一体的国防后备力量动员使用平台,形成系统完备的国防后备力量全局任务能力。     

Inventory policies for a make‐to‐order system with a perishable component and fixed ordering cost

We consider a make‐to‐order production system where two major components, one nonperishable (referred to as part 1) and one perishable (part 2), are needed to fulfill a customer order. In each period, replenishment decisions for both parts need to be made jointly before demand is realized and a fixed ordering cost is incurred for the nonperishable part. We show that a simple (s_n,S,S) policy is optimal. Under this policy, S along with the number of backorders at the beginning of a period if any and the availability of the nonperishable part (part 1) determines the optimal order quantity of the perishable part (part 2), while (s_n,S) guide when and how much of part 1 to order at each state. Numerical study demonstrates that the benefits of using the joint replenishment policy can be substantial, especially when the unit costs are high and/or the profit margin is low. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2009     

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.     

论军队党组织建设基本矛盾

运用科学发展观的立场、观点和方法,立足军队党组织建设80余年的历史发展,特别是改革开放以来新的伟大实践,概括军队党组织建设的基本矛盾:"适应时代发展、国家安全形势变化的需求建设军队与军队党组织领导能力、自身建设现实状况不能及时、完全满足这种需求之间的矛盾."从生成机理、表现形态与时空维度论证这一基本矛盾认定的科学性;从"三个主体要素"结构而成的"两对矛盾"揭示这一基本矛盾的丰富内涵;从军队党建学科理论满足实践发展需求的视角,提出新形势下遵循基本矛盾规律创新军队党建学科理论、改革军队党组织建设的对策性思路.     

从一介书生到伟大的军事家——对毛泽东成为伟大军事家的原因分析

毛泽东是世界上最杰出的军事家之一.然而,青年时代的毛泽东并没有想到要去搞军事,更没有想要成为一位伟大的军事家,其最大的愿望,一是当个教员,二是当一名新闻记者.1921年初,毛泽东在新民学会讨论"会员个人生活方法"时,表示:"我可愿做的工作:一教书,一新闻记者,将来多半要赖这两项工作的月薪来生活."(<毛泽东传(1893-1949年)>上,73页,北京,中央文献出版社,1996)后来,毛泽东又回忆说:"我搞过国民革命军政治部的宣传工作,在农民运动讲习所也讲过打仗的重要,可就是从来没有想到自己去搞军事,要去打仗."     

Planning gamma accelerated degradation tests with two accelerating variables

Gamma accelerated degradation tests (ADT) are widely used to assess timely lifetime information of highly reliable products with degradation paths that follow a gamma process. In the existing literature, there is interest in addressing the problem of deciding how to conduct an efficient, ADT that includes determinations of higher stress‐testing levels and their corresponding sample‐size allocations. The existing results mainly focused on the case of a single accelerating variable. However, this may not be practical when the quality characteristics of the product have slow degradation rates. To overcome this difficulty, we propose an analytical approach to address this decision‐making problem using the case of two accelerating variables. Specifically, based on the criterion of minimizing the asymptotic variance of the estimated q quantile of lifetime distribution of the product, we analytically show that the optimal stress levels and sample‐size allocations can be simultaneously obtained via a general equivalence theorem. In addition, we use a practical example to illustrate the proposed procedure.     

一种海上编队通信的反干扰效能评估方法

针对海上编队通信反干扰效能评估问题,建立了海上编队通信反干扰效能评估指标体系。利用直觉模糊集描述评估指标值,基于熵的物理意义采用模糊熵在指标权重完全未知的情况下求取指标权重,利用同时考虑指标权重和位置权重的IFHA算子集结指标信息,提供效能评估方法,并利用直觉模糊数排序方法比较待评估方案优劣,对方法进行了实例分析。所提供的方法很大程度克服了评估过程中主观因素的影响,对研究类似问题具有借鉴意义。