Dynamic capacity reservation and due date quoting in a make‐to‐order system

We consider a make‐to‐order manufacturer facing random demand from two classes of customers. We develop an integrated model for reserving capacity in anticipation of future order arrivals from high priority customers and setting due dates for incoming orders. Our research exhibits two distinct features: (1) we explicitly model the manufacturer's uncertainty about the customers' due date preferences for future orders; and (2) we utilize a service level measure for reserving capacity rather than estimating short and long term implications of due date quoting with a penalty cost function. We identify an interesting effect (“t‐pooling”) that arises when the (partial) knowledge of customer due date preferences is utilized in making capacity reservation and order allocation decisions. We characterize the relationship between the customer due date preferences and the required reservation quantities and show that not considering the t‐pooling effect (as done in traditional capacity and inventory rationing literature) leads to excessive capacity reservations. Numerical analyses are conducted to investigate the behavior and performance of our capacity reservation and due date quoting approach in a dynamic setting with multiple planning horizons and roll‐overs. One interesting and seemingly counterintuitive finding of our analyses is that under certain conditions reserving capacity for high priority customers not only improves high priority fulfillment, but also increases the overall system fill rate. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

Dynamic inventory management with cash flow constraints

In this article, we consider a classic dynamic inventory control problem of a self‐financing retailer who periodically replenishes its stock from a supplier and sells it to the market. The replenishment decisions of the retailer are constrained by cash flow, which is updated periodically following purchasing and sales in each period. Excess demand in each period is lost when insufficient inventory is in stock. The retailer's objective is to maximize its expected terminal wealth at the end of the planning horizon. We characterize the optimal inventory control policy and present a simple algorithm for computing the optimal policies for each period. Conditions are identified under which the optimal control policies are identical across periods. We also present comparative statics results on the optimal control policy. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2008     

基于多层次Petri网的软件保障流程建模

软件保障流程分析是研究软件保障规律的重要手段。应用多层赋时变迁、随机Petri网技术,逐步细化建立了软件保障流程仿真模型,给出了各层次模型中库所和变迁的含义。结合模型的仿真分析,提出了用"软件使用保障时间比"作为评价软件保障性的参数,给出了软件使用保障时间比的计算方法,并就该计算方法所表达的意义同装备系统进行了比较,指出了软件使用与保障时间分配的特殊性。     

雾化液滴在气道内的动力学特性及其影响因素

基于单颗粒动力学,用Lagrangian方法建立了液滴在气道内运动的数学模型,用Runge-Kutta法对液滴运动方程进行了数值求解,得到了液滴速度、相对雷诺数和阻力系数沿气道轴向的变化规律,并分析了重力场、液滴粒径、液滴初始速度、液滴出射角度对液滴运动轨迹的影响.结果表明,液滴在气道内的运动分为变速段和恒速段,液滴粒径、初始速度及出射角度等因素对雾滴的运动轨迹也有很大影响,雾滴运动分析时一般不应忽略重力场的作用.     

基于神经网络的舰船建造费用预测分析

采用了一种基于神经网络的舰船建造费预测方法 .计算结果表明 ,这种方法与传统的参数法相比较 ,有更好的估算精度 ,因而该方法可以作为研究此类问题的新途径     

一种无人战斗机系统使用保障费用分析方法

基于无人战斗机系统在使用保障上的特点,通过对有人战斗机使用保障费用模型进行合理改造,使其能适用于无人战斗机的使用保障费用分析。经过改造的模型具有结构清晰、概念明确的特点。适合在飞机总体设计阶段用于全寿命周期的费用估算以及飞机的费效分析和综合优化设计。通过与有人战斗机的使用保障费用进行对比计算表明,无人战斗机系统的使用保障费用具有明显的经济优势。     

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     

海峡两岸出入境管理问题研究

从出入境管理的角度,分析两岸人员往来管理工作的现状及存在的问题,提出海峡两岸出入境管理工作要适应当前出入境人员大进大出、快进快出的形势,简化出入境手续,切实保障海峡两岸“三通”的顺利进行,进而推动两岸的交流与合作。     

试论武器装备的效费比分析

运用价值工程(VE)方法分析武器装备,称效费比为价值。按照杜佩(Dupuy)的方法,把武器装备的效能转化为“战斗效能值”(OLI),又计算出了武器装备的全寿命费用,然后将2者加以对比,获得效能—费用的最佳组合,同时提出了选择武器装备系统的定量分析方法。这些对于提高我国国防经济效益,具有一定的指导和借鉴意义。