Optimal empty vehicle redistribution for hub‐and‐spoke transportation systems

This article considers the empty vehicle redistribution problem in a hub‐and‐spoke transportation system, with random demands and stochastic transportation times. An event‐driven model is formulated, which yields the implicit optimal control policy. Based on the analytical results for two‐depot systems, a dynamic decomposition procedure is presented which produces a near‐optimal policy with linear computational complexity in terms of the number of spokes. The resulting policy has the same asymptotic behavior as that of the optimal policy. It is found that the threshold‐type control policy is not usually optimal in such systems. The results are illustrated through small‐scale numerical examples. Through simulation the robustness of the dynamic decomposition policy is tested using a variety of scenarios: more spokes, more vehicles, different combinations of distribution types for the empty vehicle travel times and loaded vehicle arrivals. This shows that the dynamic decomposition policy is significantly better than a heuristics policy in all scenarios and appears to be robust to the assumptions of the distribution types. © 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008     

通用装备机械液压系统综合检测试验平台运用问题研究

论述了通用装备机械液压系统综合检测试验平台的功能、组成结构、特点及对平台的初步认识,从使用时机、平台的编配、平台的质量管理、平台保障数据库建设、平台的应用等方面,对平台的运用问题进行了研究,并从平时保障的角度对平台提出改进建议。     

基于分布式天线的认知无线电系统感知算法和信道容量分析

认知无线电概念的提出为频谱的共享提供了可能。文中提出一种基于分布式天线的认知无线电系统实现方法,该方法便于频谱的感知,能降低对首要用户的干扰,并且相对于中心式天线能为次要认知无线电用户的下行链路提供较大的信道容量增益。     

基于多Agent仿真的装备保障体系供应保障系统设计与实现?

针对部队装备保障运行的实际情况,采用多Agent仿真的方法,基于Kraljic模型将装甲装备器材分为重要器材、关键器材、一般器材和稀缺器材,并以此为基础构建了装备保障体系供应保障系统。分析了系统的整体结构以及系统中器材仓库的外部接口和内部器材请领流程,并以某集团军各级器材仓库为研究对象进行了仿真实例分析。实践证明,采用多Agent仿真的方法研究装备保障体系供应保障活动具备可行性和有效性,有利于宏观把握部队装备保障的运行规律,提高部队装备保障能力。     

空中突击部队装备体系作战任务建模方法研究

空中突击部队是由多装备系统组成的装备体系,在执行任务过程中体现多阶段多任务的特点。基于DoDAF体系框架,结合美军空中突击部队装备体系作战任务展开研究。首先,通过作战任务的形式化描述,建立了装备体系作战任务的四元组描述模型;其次,在DoDAF体系框架下,提出建立空中突击部队装备体系作战任务的静态模型和动态模型;最后通过仿真方法对动态模型进行验证,证明了该模型的可信性。     

基于构件的决策支持系统中模型组织集成框架IFMO

决策支持系统模型组织和表示是影响模型和建模效果的一个基本问题 ,也是实现模型管理的前提。在研究国内外建模技术以及开发CS -DSSP决策支持系统开发平台[1] [2 ] 的基础上 ,本文提出了一种基于构件的模型组织集成框架 ,包括模型构件化描述、构件化框架、集成框架体系结构等。IFMO提出了一种把先进建模技术应用到DSS中的方法     

近似推理在水雷参数分析专家系统中的应用

为了尽快分析出未知水雷障碍参数,根据水雷战的特点,提出了建立未知水雷障碍参数分析专家系统的观点,对专家系统的设计方法进行了一定的探讨,并针对专家系统建立中的"瓶颈"问题,提出了基于Vague集插值近似推理的专家系统知识自动获取方法,在介绍推理过程的基础上给出了算例.从推理的结果来看,该方法具有较高的可信度,从而为专家系统的研制提供了一定的方法支持.     

Lateral stock transshipments in a two‐location inventory system with fixed and joint replenishment costs

We address the problem of inventory management in a two‐location inventory system, in which the transshipments are carried out as means of emergency or alternative supply after demand has been realized. This model differs from previous ones as regards its replenishment costs structure, in which nonnegligible fixed replenishment costs and a joint replenishment cost are considered. The single period planning horizon is analyzed, with the form and several properties of the optimal replenishment and transshipment policies developed, discussed and illustrated. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 525–547, 1999     

图像质量主客观评价的相关性分析

图像质量的客观评价与人类主观感知之间一定存在必然的联系,并且这些客观评价方法应该取代主观评价。也就是说,这些客观评价方法允许在不征求任何用户意见的基础上,去评价一个给定系统的性能。本文研究了在变化的压缩体制下实施在若干图像上的一套客观测量和主观评价之间的相互关系,并给出了初步的分析结果。     

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