Multi-class inventory models with demand a function of inventory level

This paper considers the problem of maintaining an inventory of an item which can deteriorate and become useless. A periodic review procedure is used and new items ordered may experience a time lag in delivery. Items are considered to deteriorate through one or two states before becoming useless. Thus the deterioration process in each period plays the role of the usual demand process and is a function of the inventory level at the beginning of each period. For the case of no time lag in delivery, one stage deterioration, and either binomial or uniform deterioration, optimal ordering policies are obtained for the n-period dynamic model with the standard cost structure. (For the shortage probability criterion see the other paper by Iglehart and Jaquette, in this issue.) These policies are of the single critical number type. For more complicated models suboptimal policies of this same type are found.     

Effectiveness of (R,Q) policies in one‐warehouse multiretailer systems with deterministic demand and backlogging

Consider a distribution system with a central warehouse and multiple retailers. Customer demand arrives at each of the retailers continuously at a constant rate. The retailers replenish their inventories from the warehouse which in turn orders from an outside supplier with unlimited stock. There are economies of scale in replenishing the inventories at both the warehouse and the retail level. Stockouts at the retailers are backlogged. The system incurs holding and backorder costs. The objective is to minimize the long‐run average total cost in the system. This paper studies the cost effectiveness of (R, Q) policies in the above system. Under an (R, Q) policy, each facility orders a fixed quantity Q from its supplier every time its inventory position reaches a reorder point R. It is shown that (R, Q) policies are at least 76% effective. Numerical examples are provided to further illustrate the cost effectiveness of (R, Q) policies. © 2000 John Wiley & Sons, Inc. Naval Research Logistics 47: 422–439, 2000     

Centralized inventory control in a two‐level distribution system with Poisson demand

This paper introduces a new replenishment policy for inventory control in a two‐level distribution system consisting of one central warehouse and an arbitrary number of nonidentical retailers. The new policy is designed to control the replenishment process at the central warehouse, using centralized information regarding the inventory positions and demand processes of all installations in the system. The retailers on the other hand are assumed to use continuous review (R, Q) policies. A technique for exact evaluation of the expected inventory holding and backorder costs for the system is presented. Numerical results indicate that there are cases when considerable savings can be made by using the new (α₀, Q₀) policy instead of a traditional echelon‐ or installation‐stock (R, Q) policy. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 798–822, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10040     

系级教学评估工作刍议

实施系级教学评估工作是高校教学质量内部保障措施之一 ,具有十分重要的意义 ;系级教学评估具有具体化、导向、比较、信息收集作用 ;系级教学评估具有日常性、主体性、可信性、开放性特征 ;确保系级教学评估的组织实施。     

An efficient heuristic procedure for the capacitated warehouse location problem

This paper introduces an efficient heuristic procedure for solving a special class of mixed integer programming problem called the capacitated warehouse (plant) location problem. This procedure parallels the work reported earlier in [9] on the uncapacitated warehouse location problem. The procedure can be viewed as tracing a judiciously selected path of the branch and bound tree (from the initial node to the terminal node) to arrive at a candidate solution. A simple backtracking scheme is also incorporated in the procedure to investigate possible improvement in the solution. Computational results on problems found in the literature look quite encouraging.     

An efficient heuristic procedure for the uncapacitated warehouse location problem

This paper introduces an efficient heuristic procedure for a special class of mixed integer programming problems called the uncapacitated warehouse (plant) location problem. This procedure is derived from the branching decision rules proposed for the branch and bound algorithm by the author in an earlier paper. It can be viewed as tracing a single path of the branch and bound tree (from the initial node to the terminal node), the path being determined by the particular branching decision rule used. Unlike branch and bound the computational efficiency of this procedure is substantially less than linearly related to the number of potential warehouse locations (integer variables) in the problem. Its computational efficiency is tested on problems found in the literature.     

词汇层面的语际借用及其成因

对词汇层面的语际借用,包括其界定、分类和某些特征作了泛语言学上的描述,并从语言、社会、文化以及民族文化心理等方面探讨了词汇层面的语际借用发生的原因.     

谈支队党委的形象及形象效应

消防支队建设要适应新形势的需要,支队党委一班人的形象至关重要.支队党委要树立团结向上、无私奉献、勤政廉政及不断探索四种形象.支队党委形象建设搞好了,才有良好的形象效应,才能解决部队建设的各种问题,不断提高部队战斗力.     

Estimating the lead-time demand distribution for an autocorrelated demand by the pearson system and a normal approximation

The exact first four moments of lead-time demand L are derived for an AR(1) and a MA(1) demand structures where the arbitrary lead-time distribution is assumed to be independent of the demand structure. These moments then form a basis for the Pearson curve-fitting procedure for estimating the distribution of L. A normal approximation to L, a version of the central limit theorem, is obtained under some general conditions. Reorder points (ROPs) of an inventory system are then estimated based on the Pearson system and a normal approximation. Their performances are evaluated. Numerical investigation shows that the Pearson system performs extremely well. The normal approximation, however, is good only for some limited cases, and is sensitive to the choice of the lead-time distribution. A possible improvement is noted.     

基层消防部队财务管理存在的问题及对策

分析基层消防部队财务管理中存在的问题 ,并提出一些解决问题的对策。     

云计算视域下的网络威慑

文章考查了目前网络威慑理论在实践中出现的困境,并研究了云计算对网络威慑的价值对象,攻防能力以及威慑模式选择的影响,认为国家的网络威慑战略将更加倾向于抵消性威慑。基于此,对我国在云计算背景下加强网络安全提出了建议。     

警戒雷达抗干扰效能的计算方法

本文针对现代战争中复杂的电子干扰环境,建立了警戒雷达抗干扰的战术效能指标,并给出 了计算方法,对于评估雷达的抗干扰性能及装备论证具有重要意义。     

Individual preferences and the demand for military expenditure*

Whose preferences determine the tradeoff between security and civilian output in deciding upon budget allocations to defence? This paper considers the role that consumer preferences might play in influencing military spending. We propose normative criteria to judge the economic or political efficiency of defence provision at a given time, and test them using Australian survey‐based micro‐data. Our results suggest that the political system has not delivered a simple social‐choice translation of individual preferences into collective outcomes, nor has it delivered results consistent with simple majority‐voting median preferences.     

Computing bounds for the optimal value in linear programming

Consider a standard linear programming problem and suppose that there are bounds available for the decision variables such that those bounds are not violated at an optimal solution of the problem (but they may be violated at some other feasible solutions of the problem). Thus, these bounds may not appear explicitly in the problem, but rather they may have been derived from some prior knowledge about an optimal solution or from the explicit constraints of the problem. In this paper, the bounds on variables are used to compute bounds on the optimal value when the problem is being solved by the simplex method. The latter bounds may then be used as a termination criteria for the simples iterations for the purpose of finding a “sufficiently good” near optimal solution. The bounds proposed are such that the computational effort in evaluating them is insignificant compared to that involved in the simplex iterations. A numerical example is given to demonstrate their performance.     

Computing the discounted return in markov and semi-markov chains

This paper addresses the problem of computing the expected discounted return in finite Markov and semi-Markov chains. The objective is to reveal insights into two questions. First, which iterative methods hold the most promise? Second, when are interative methods preferred to Gaussian elimination? A set of twenty-seven randomly generated problems is used to compare the performance of the methods considered. The observations that apply to the problems generated here are as follows: Gauss-Seidel is not preferred to Pre-Jacobi in general. However, if the matrix is reordered in a certain way and the author's row sum extrapolation is used, then Gauss-Seidel is preferred. Transforming a semi-Markov problem into a Markov one using a transformation that comes from Schweitzer does not yield improved performance. A method analogous to symmetric successive overrelaxation (SSOR) in numerical analysis yields improved performance, especially when the row-sum extrapolation is used only sparingly. This method is then compared to Gaussian elimination and is found to be superior for most of the problems generated.     

军用移动计算平台框架结构研究

介绍了军用移动计算平台概念提出的背景,提出了军用移动计算平台概念和框架结构,以地面移动计算平台为例,分析了电子控制平台、驾驶平台、信息与通信平台、火力控制平台以及战场防护平台的功能,最后分析了军用移动计算平台的应用前景。     

软计算在污水处理过程控制中的应用

阐明了软计算技术在污水处理过程中应用的必要性、可行性及对行业所带来的社会效益和理论意义,着重分析了其在污水处理过程中的应用情况,简要探讨了软计算技术今后应深入研究的问题和方向,指出将软计算算法和智能控制策略结合起来有利于提高模型预测精度,提高过程控制系统动态响应能力。     

The demand for military spending in the peripheral economies of Europe

Research on the factors that determine the level of military expenditure or military burden in countries, suggest that the dynamics of the determinants of military spending will be best understood by case studies of individual countries and studies of groups of relatively homogeneous countries. This paper provides a comparative analysis of three of the EU's peripheral economies - Greece, Portugal and Spain. A simple model based on a general theory of the demand for military spending provides the basis for an investigation of the relative importance of strategic and other social and economic factors for the three countries.     

舰船装备随行备件量需求规律分析

通过对舰船装备备件需求影响因素的分析 ,从理论上推导了备件需求的分布规律 ,在此基础上建立了舰船级备件典型需求模型 ,并且对典型的故障分布模型进行了推广     

角速率火控系统计算延迟问题的研究

提出解决角速率火控系统计算延迟问题的两种方法,为深入研究角速率火控计算进行了新的探索。