A single period model for a multiproduct perishable inventory system with economic substitution

This paper develops a single period model for a specific class of multiproduct perishable inventory systems where demands are interdependent. This class of inventory systems has the property that there is economic substitution between products. It is shown that the optimal policy has the economic substitution property, and that the rate of substitution is age dependent. The model serves as a generalization of a theorem discovered by Ignall and Veinott.     

Optimal arrangement of components via pairwise rearrangements

We introduce the notion of comparison of the criticality of two nodes in a coherent system, and devlop a monotonicity property of the reliability function under component pairwise rearrangement. We use this property to find the optimal component arrangement. Worked examples illustrate the methods proposed.     

战场图像情报侦察处理技术及其发展

为了及时了解和掌握图像侦察领域最新的处理技术和发展动态,研究了战场图像情报的特点,主要获取手段,美军目前使用的几种典型战场图像侦察装备,战场侦察图像的融合处理和关键技术。     

基于光流传感器的四旋翼飞行器悬停校正

由于低成本的惯性测量单元存在较大漂移,四旋翼飞行器难以稳定地悬停在固定区域,基于此,提出了一种基于光流传感器的四旋翼飞行器悬停校正方法。将光流传感器安装在四旋翼飞行器底部,利用光流信息检测四旋翼飞行器相对地面的水平移动速度,对姿态估计进行补偿,实现悬停校正。试验结果表明:该方法能够有效地提高四旋翼飞行器的悬停稳定性,从而保证飞行器能够执行战场侦察、校正射击、干扰敌人等多种军事任务。     

一类多时滞泛函微分方程周期正解的存在性

利用非线性泛函分析中半序Banach空间的锥理论和不动点指数方法,讨论了一类多时滞泛函微分方程周期正解的存在性问题,并得到此类多时滞泛函微分方程周期正解存在的几个充分条件。     

基于FPGA的DBF设计与实现

充分利用FPGA资源丰富、处理灵活等优势,采用FPGA技术实现了高带宽、高精度的DBF系统,能够与DSP系统互通,接收来自DSP系统的权值。系统通过测试,性能良好。     

Capacity allocation with traditional and Internet channels

In this paper we study a capacity allocation problem for two firms, each of which has a local store and an online store. Customers may shift among the stores upon encountering a stockout. One question facing each firm is how to allocate its finite capacity (i.e., inventory) between its local and online stores. One firm's allocation affects the decision of the rival, thereby creating a strategic interaction. We consider two scenarios of a single‐product single‐period model and derive corresponding existence and stability conditions for a Nash equilibrium. We then conduct sensitivity analysis of the equilibrium solution with respect to price and cost parameters. We also prove the existence of a Nash equilibrium for a generalized model in which each firm has multiple local stores and a single online store. Finally, we extend the results to a multi‐period model in which each firm decides its total capacity and allocates this capacity between its local and online stores. A myopic solution is derived and shown to be a Nash equilibrium solution of a corresponding “sequential game.” © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2006     

Risk pooling in a two-period,two-echelon inventory stocking and allocation problem

The object of this article is to investigate the risk-pooling effect of depot stock in two-echelon distribution system in which the depot serves n retailers in parallel, and to develop computationally tractable optimization procedures for such systems. The depot manager has complete information about stock levels and there are two opportunities to allocate stock to the retailers within each order cycle. We identify first- and second-order aspects to the risk-pooling effect. In particular, the second-order effect is the property that the minimum stock available to any retailer after the second allocation converges in probability to a constant as the number of retailers in the system increases, assuming independence of the demands. This property is exploited in the development of efficient procedures to determine near-optimal values of the policy parameters.     

Optimizing disaster relief: Real-time operational and tactical decision support

We introduce a real-time decision support system which uses optimization methods, simulation, and the judgement of the decision maker for operational assignment of units to tasks and for tactical allocation of units to task requirements. The system, named ARES for the Greek god of war, accommodates a high degree of detail in the logistics of unit movements during operations, yet separates the assignment and allocation activities in a fashion which naturally accommodates human intervention and judgement—ARES is designed to assist the decision maker, not to replace him. ARES is demonstrated with a hypothetical scenario constructed for 14 Engineering Battalions of the Hellenic Army which are assigned 20 tasks employing 25 resource types in repairing major damage to public works following a great earthquake. (This hypothetical data was prepared prior to the earthquake in Kalamata near Athens on 13 September, 1986, and exhibits uncanny, but coincidental, resemblance to that real situation.) ARES is designed for use in real time, and quick data preparation is aided by the provision from published sources of standard data for many foreseeable tasks; this data can be quickly accessed via visual icons on a computer screen and customized for the actual work at hand. © 1993 John Wiley & Sons, Inc.     

A new surrogate dual multiplier search procedure

Efficient computation of tight bounds is of primary concern in any branch-and-bound procedure for solving integer programming problems. Many successful branch-and-bound approaches use the linear programming relaxation for bounding purposes. Significant interest has been reported in Lagrangian and surrogate duals as alternative sources of bounds. The existence of efficient techniques such as subgradient search for solving Lagrangian duals has led to some very successful applications of Lagrangian duality in solving specially structured problems. While surrogate duals have been theoretically shown to provide stronger bounds, the difficulty of surrogate dual-multiplier search has discouraged their employment in solving integer programs. Based on the development of a new relationship between surrogate and Lagrangian duality, we suggest a new strategy for computing surrogate dual values. The proposed approach allows us to directly use established Lagrangian search methods for exploring surrogate dual multipliers. Computational experience with randomly generated capital budgeting problems validates the economic feasibility of the proposed ideas.