The initial provisioning decision for insurance type items

Initial provisioning decisions (inventory stocking requirements) for low demand items often have to be made without much knowledge of what future demand rates will be. When the nature of an item is such that little demand for it is expected, the problem of whether to stock initially or risk not stocking the item is most critical. This report discusses this problem and presents decision procedures which can be used to handle this aspect of initial provisioning. The procedures relate an item's provisioning desirability to its provisioning characteristics, such as expected cost, expected resupply time, current information on its likely demand rate, and to an overall operating policy or criterion. The criterion function measures the total system degredation as a function of the events of having items out of stock when demand occurs. Several different policy functions are discussed and the provisioning decision rules which apply to each are presented. Demand rate information is handled through a Bayesian type approach. The decision rules presented in this report can be utilized to either determine stocking requirements within a budgetary constraint, or determine the relative stocking desirability on an item-by-item basis.     

Queueing models for spares provisioning

A population of items which break down at random times and require repair is studied (the classic “machine repair problem with spares”). It is desired to determine the number of repair channels and spares required over a multiyear planning horizon in which population size and component reliability varies, and a service level constraint is imposed. When an item fails, a spare (if available) is immediately dispatched to replace the failed item. The failed item is removed, transported to the repair depot, repaired, and then placed in the spares pool (which is constrained to be empty not more than 10% of the time) unless there is a backlog of requests for spares, in which case it is dispatched immediately. The first model considered treats removal, transportation, and repair as one service operation. The second model is a series queue which allows for the separate treatment of removal, transportation, and repair. Breakdowns are assumed Poisson and repair times exponential.     

A Bayesian approach to demand estimation and inventory provisioning

This article addresses the problem of explicitly taking into account uncertainty about the demand for spare parts in making inventory procurement and stockage decisions. The model described provides for a unified treatment of the closely related problems of statistical estimation of demand and resource allocation within the inventory system, and leads to an easily implemented, efficient method of determining requirements for spare parts both in the early provisioning phase and in later periods of operations when demand data have accumulated Analyses of the model's theoretical foundations and of sample outcomes of the model based upon data on parts intended for use in the F-14 lead to conclusions of great importance to both support planners and operations planners Finally, of particular significance is the ability afforded the planner by this model to quantify the impact on inventory system costs of varying levels of system reliability or management uncertainty as to projected system performance. This will provide an economic basis for analysis of such alternatives as early deployment, operational testing, and equipment redesign.     

Multiechelon repairable-item provisioning in a time-varying environment using the randomization technique

Multiechelon repairable-item provisioning systems are considered under a time-varying environment. Such conditions could arise, for example, in a military context where a shift from peacetime operation to wartime operation takes place; or, in a civilian setting where a public transit system decides to increase its hours of operation or frequency of service. Exact Markovian models, incorporating a finite population of repairable components and limited repair capacity (nonample service), are treated, with transient solutions obtained using the randomization technique. The exact models are compared with the approximate Dyna-METRIC model which assumes an infinite population of components and ample repair capacity.     

Economic ordering quantities for recoverable item inventory systems

We study a deterministic EOQ model of an inventory system with items that can be recovered (repaired/refurbished/remanufactured). We use different holding cost rates for manufactured and recovered items, and include disposal. We derive simple square root EOQ formulas for both the manufacturing batch quantity and the recovery batch quantity.     

An analysis of single item inventory systems with returns

Inventory systems with returns are systems in which there are units returned in a repairable state, as well as demands for units in a serviceable state, where the return and demand processes are independent. We begin by examining the control of a single item at a single location in which the stationary return rate is less than the stationary demand rate. This necessitates an occasional procurement of units from an outside source. We present a cost model of this system, which we assume is managed under a continuous review procurement policy, and develop a solution method for finding the policy parameter values. The key to the analysis is the use of a normally distributed random variable to approximate the steady-state distribution of net inventory. Next, we study a single item, two echelon system in which a warehouse (the upper echelon) supports N(N ? 1) retailers (the lower echelon). In this case, customers return units in a repairable state as well as demand units in a serviceable state at the retailer level only. We assume the constant system return rate is less than the constant system demand rate so that a procurement is required at certain times from an outside supplier. We develop a cost model of this two echelon system assuming that each location follows a continuous review procurement policy. We also present an algorithm for finding the policy parameter values at each location that is based on the method used to solve the single location problem.     

Expressions for item fill rates in periodic inventory systems

We examine the problem of estimating the item fill rate in a periodic inventory system. We show that the traditional expressions for line item fill rate, found in many operations management textbooks, perform well for high fill rates (above 90%), but they consistently underestimate the true fill rate. The problem of underestimation becomes significant as the fill rate falls below 90% and is greatly amplified in cases with very low fill rates (below 50%). We review other more accurate expressions for fill rate, discussing their relative merits. We then develop an exact fill rate expression that is robust for both high and low fill rates. We compare the new expression to others found in the literature via an extensive set of simulation experiments using data that reflect actual inventory systems found at Hewlett-Packard. We also examine the robustness of the expressions to violations in the underlying assumptions. Finally, we develop an alternative fill rate expression that is robust for cases of high demand variability where product returns are allowed. © 1995 John Wiley & Sons, Inc.     

A sequential attribute sampling inspection game for item facilities

The routine inspection of facilities storing large numbers of identical items is modeled as a two‐person, sequential game. Timely detection of illegal activity is parameterized in terms of a critical time to detection, and equilibria are derived which provide inspection strategies. Necessary conditions for deterrence of illegal behavior are discussed. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 496–505, 2001     

Expected time delay in multi‐item inventory systems with correlated demands

This paper considers multi‐item inventory systems where a customer order may require several different items (i.e., demands are correlated across items) and customer satisfaction is measured by the time delays seen by the customers. Most inventory models on time delay in the literature assume each demand only requires one item (i.e., demands are not correlated across items or are independent). In this paper, we derive an exact expression for the expected total time delay. We show that when items are actually correlated, assuming items are independent leads to an overestimate of the total time delay. However, (1) it is extremely difficult in practice to obtain the demand information for all demand types (especially in a system with tens of thousands of part numbers), and (2) the problem becomes too complicated to be of practical interest when the correlation is considered. We then explore the possibility of including the demand information partially and develop bounds for the time delays. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 671–688, 1999     

基于工作分解结构的装备作战试验项目设计与评价

试验项目是装备试验鉴定资源分配、实施及数据产生与采集的基本单元。要经济高效地完成规定的装备试验鉴定任务,必须设计与试验目的相关联的、完备可行的试验项目清单。本文界定了装备作战试验项目的概念,分析了装备作战试验项目的六个特征,归纳了装备作战试验项目设计的四条原则,并基于现代项目管理的工作分解结构（Work Breakdown Structure,简称WBS）技术提出了装备作战试验项目设计的两种方法,即基于装备能力的作战试验项目设计和基于任务过程的作战试验项目设计,通过对设计原则和要求的细化建立了装备作战试验项目设计结果评价的指标体系,并给出了综合评价思路,用来为装备作战试验项目设计提供指导。     

基于支持向量机的武器系统研制项目评估分析

对常规评估方法和支持向量机模型用于武器系统研制项目评估进行了分析和比较,着重分析了应用支持向量机进行武器系统研制项目重要度评估的具体形式以及方法特点,通过实例进行了分析验证,取得了满意的结果.     

警卫形式的地位及应把握的关系和原则

新形势下,要做好警卫工作,必须在具体工作中把握警卫形式与安全第一的关系、内紧外松的关系、警卫形式警卫基础工作的关系,以及警卫形式"适度"、从实际出发的原则.     

Selecting review periods for a coordinated multi‐item inventory model with staggered deliveries

Consider an N‐item, periodic review, infinite‐horizon, undiscounted, inventory model with stochastic demands, proportional holding and shortage costs, and full backlogging. For 1 ≤ j ≤ N, orders for item j can arrive in every period, and the cost of receiving them is negligible (as in a JIT setting). Every T_j periods, one reviews the current stock level of item j and decides on deliveries for each of the next T_j periods, thus incurring an item‐by‐item fixed cost k_j. There is also a joint fixed cost whenever any item is reviewed. The problem is to find review periods T₁, T₂, …, T_N and an ordering policy satisfying the average cost criterion. The current article builds on earlier results for the single‐item case. We prove an optimal policy exists, give conditions where it has a simple form, and develop a branch and bound algorithm for its computation. We also provide two heuristic policies with O(N) computational requirements. Computational experiments indicate that the branch and bound algorithm can handle normal demand problems with N ≤ 10 and that both heuristics do well for a wide variety of problems with N ranging from 2 to 200; moreover, the performance of our heuristics seems insensitive to N. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48:430–449, 2001     

Transient behavior of large Markovian multiechelon repairable item inventory systems using a truncated state space approach

Calculations for large Markovian finite source, finite repair capacity two-echelon repairable item inventory models are shown to be feasible using the randomization technique and a truncated state space approach. More complex models (involving transportation pipelines, multiple-item types and additional echelon levels) are also considered.     

火灾风险与保险调控初探

分析了国外保险与消防之间的相互关系和合作经验,简述了我国保险和消防存在合作的相互需要,探讨了运用保险调控火灾风险的措施。     

军人伤亡保险存在的问题探析

军人伤亡保险作为军人保险制度的重要组成部分,其经济补偿功能已经被广大官兵逐渐认可。但作为分散军人职业风险的特定机制,其作用并未被充分开发出来,主要表现在较低的补偿水平等方面。因此,应充分借鉴国内外的相关经验,扬长避短,以充分发挥军人伤亡保险的作用。     

新消防法下保险与消防良性互动机制探析

根据新《消防法》国家鼓励保险公司承担火灾公众责任保险的规定,阐述了保险业在火灾公众责任保险中发挥经济补偿的功能和作用,有利于消防工作社会化和提高公共消防安全保障,并就如何开展良性互动机制进行分析。     

随军配偶未就业期间社会保险问题分析

军人配偶随军未就业期间社会保险的建立解决了军人配偶在随军未就业期间的基本生活补贴和养老、医疗保险问题,在一定程度上保障了随军配偶的利益。但在执行过程中也出现一些诸如险种较少,保障范围较窄,保障程度较低等问题。在分析存在问题的基础上,提出一些完善社会保险的建议。     

火灾公众责任保险与消防治理问题研究

阐述了火灾公众责任保险的涵义,分析了火灾公众责任保险在消防治理中的作用,梳理了火灾公众责任保险的发展现状问题,进而提出消防治理视阈下火灾公众责任保险的发展思路。     

基于火灾风险评估的商场保险费率厘定研究

结合火灾公众责任保险的推广,从火灾风险评估和火灾保险费率厘定两个方面入手,通过专家打分,采用层次分析法对火灾风险进行半定量评估,得到了商场建筑火灾风险评估的指标体系。然后,提出基于神经网络的火灾保险与保险费率的对应机理,得到指标权重与费率对应关系,进而通过某商场投保实例验证此方法的可行性和合理性。