Coordinated pricing and inventory control problems with capacity constraints and fixed ordering cost

This article addresses a single‐item, finite‐horizon, periodic‐review coordinated decision model on pricing and inventory control with capacity constraints and fixed ordering cost. Demands in different periods are random and independent of each other, and their distributions depend on the price in the current period. Each period's stochastic demand function is the additive demand model. Pricing and ordering decisions are made at the beginning of each period, and all shortages are backlogged. The objective is to find an optimal policy that maximizes the total expected discounted profit. We show that the profit‐to‐go function is strongly CK‐concave, and the optimal policy has an (s,S,P) ‐like structure. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

Parametric inference for component distributions from lifetimes of systems with dependent components

In system reliability analysis, for an n ‐component system, the estimation of the performance of the components in the system is not straightforward in practice, especially when the components are dependent. Here, by assuming the n components in the system to be identically distributed with a common distribution belonging to a scale‐family and the dependence structure between the components being known, we discuss the estimation of the lifetime distributions of the components in the system based on the lifetimes of systems with the same structure. We develop a general framework for inference on the scale parameter of the component lifetime distribution. Specifically, the method of moments estimator (MME) and the maximum likelihood estimator (MLE) are derived for the scale parameter, and the conditions for the existence of the MLE are also discussed. The asymptotic confidence intervals for the scale parameter are also developed based on the MME and the MLE. General simulation procedures for the system lifetime under this model are described. Finally, some examples of two‐ and three‐component systems are presented to illustrate all the inferential procedures developed here. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

在军援装备物资科研订购中引入激励机制探析

军援装备物资的订购筹措是军事援助中较为重要的一项工作.在军援装备科研订购过程中充分利用经济杠杆的调节和行政手段的调控,通过招标竞争、利益诱导、资金保障、实施奖惩等方面的具体措施,通过履行合同、择优订货等环节的激励,最大限度地调动和发挥各方面的积极性,逐步建立适应军援装备发展需要和社会主义市场经济的新型军援装备科研订购体制.     

具有战时随机延误与损耗的多配送中心路径优化

建立了具有战时随机延误与损耗的多配送中心配送路径安排模型,给出了基于随机模拟的蚁群算法。算法通过给定残存率、用时与置信度阈值,把多目标问题作为单目标来处理。用随机模拟的方法来求路径的置信度,并以此为基础搜索转移策略的临域与判断未遍历点的插入位置。算法设计了符合问题特点的从虚拟点出发的转移策略与对两类路段不同的信息素更新策略,确保算法的实现。最后,通过算例说明了该方法的可行性与有效性。     

信息熵和判断矩阵的专家聚类赋权法

为了降低专家聚类赋权过程中由排序向量引起的不确定性和判断矩阵引起的矛盾性,提高权值分配的精确性,提出了基于信息熵和判断矩阵相结合的专家聚类赋权法。该方法采用聚类分析原理,对排序向量进行分类,根据分类结果、信息熵值和一致性比率确定专家权重系数。实例分析表明:基于信息熵和判断矩阵相结合的专家聚类赋权法在具体应用中得到的结果离期望值更近,说明该算法有效可行。     

主被动传感器异地配置下的航迹关联

在雷达和电子支援(ESM)传感器异地配置的情况下,提出了一种基于位置统计量和最大似然准则的异类传感器航迹关联算法。首先基于位置统计量对目标进行了航迹粗关联,排除掉一些虚假关联组合;然后采用最大似然准则对目标进行了航迹细关联,以求进一步提高雷达和ESM传感器航迹关联的检测概率。仿真结果表明,该算法能够快速、准确地完成对多目标的航迹关联。     

考虑Reissner效应的功能梯度柱壳裂纹高阶渐近场

针对考虑Reissner效应的功能梯度柱壳裂纹问题,通过分离变量和级数展开法构造广义位移函数,求得了裂纹尖端高阶渐近场。结果表明：该解类似于Williams解,为此类问题的特征函数,能够描述此类材料各种含裂纹结构的整个应力场和位移场;材料非均匀性对高阶项有显著影响。     

高灵敏度GPS软件接收机捕获算法

针对传统方法难以实现室内环境下GPS信号的捕获以及传统弱信号捕获算法的一系列弊端,介绍了一种新的捕获算法。由于数据段通过“先累加后相关”的方式进行相干积分可以减少运算量,以此方法改进的半位捕获法进行数据段选择可以避免导航数据位翻转,并且改进后的差分相干积分能够减小非相干积分造成的“平方损失”和改善信噪比,融合上述优点,提出了一种新的算法,为高灵敏度GPS软件接收机的实现提供了保证。仿真结果表明,此算法极大的提高了接收机的捕获性能,并且能够快速捕获到载噪比低至25dB/Hz的微弱信号。     

System reliability based on diffusion models for fatigue crack growth

Diffusion processes are commonly used to describe the dynamics of complex systems arising in a wide range of application fields. In this paper we propose, on the basis of diffusion processes, two models concerned with the stochastic behavior of fatigue cracks in a system. They are then used to get the distribution of the failure time, the first time the crack size of at least one of the cracks exceeds a given value. Several properties of our proposed models are presented, and the unknown parameters are estimated by the method of maximum likelihood. From these an estimate of failure time distribution is obtained. In this part, contrary to common practice, we do not assume availability of failure data. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

Properties of the geometric and related processes

Some properties of the geometric process are studied along with those of a related process which we propose to call the α‐series process. It is shown that the expected number of counts at an arbitrary time does not exist for the decreasing geometric process. The decreasing version of the α‐series process does have a finite expected number of counts, under certain conditions. This process also has the same advantages of tractability as the geometric process; it exhibits some properties which may make it a useful complement to the increasing geometric process. In addition, it may be fit to observed data as easily as the geometric process. Applications in reliability and stochastic scheduling are considered in order to demonstrate the versatility of the alternative model. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005