地图数据库中基本图形对象的拓扑关系及其编辑

地图数据库是地理信息系统（ＧＩＳ）的核心。本文提出面向对象地图数据库的逻辑数据模型和数据结构,分析了地图的基本图形对象（结点和弧段）间的拓扑关系,围绕地图数据库的拓扑一致性,讨论了各种编辑操作的实现步骤。     

船用反应堆堆芯放射性核素总量计算

采用KORIGEN程序对船用堆的堆芯放射性核素总量进行了计算,并对连续满功率运行和实际变功率运行的计算结果进行了分析与比较,探讨了放射性核素总量随功率运行史的变化规律.     

一种使用可用度备件库存模型

阐述了以装备战备完好性为中心的备件库存控制的基本原理,并给出了以可用度为中心的备件库存数学模型.该模型可计算装备细目结构中的所有组件在各级维修机构中的库存水平,在满足一定费用约束条件下,使装备的使用可用度达到最大.     

论管理协议细栈MTS的构造

开放系统互连管理 OSIM 是 OSI 参考模型中定义的特定应用服务元素 SASE 之一,也是唯一涉及全部七层协议的服务元素。OSIM 在控制和协调 Multivendor 和 Multidomain系统中所起的作用已使它成为改进网络性能和服务水平的关键性因素。并非所有开放系统均能提供全七层支持,因此,本文提出一种管理协议细栈 MTS(Management Thin Stack)结构,讨论了它自身的构造性特及其在上述管理环境下的作用。     

阻止差分密码攻击的有效方法

差分密码分析方法是1990年由E.Biham和A.Shamir提出的,这种方法对DES算法及DES类体制构成了威胁。本文在剖析了差分密码分析方法工作原理的基础上,提出了改进DES算法的7种方法,从而可以有效地阻止差分密码分析法的攻击。     

On the availability of R out of N repairable systems

An R out of N repairable system consisting of N components and operates if at least R components are functioning. Repairable means that failed components are repaired, and upon repair completion they are as good as new. We derive formulas for the expected up‐time, expected down‐time, and the availability of the system, using Markov renewal processes. We assume that either the repair times of the components are generally distributed and the components' lifetimes are exponential or vice versa. The analysis is done for systems with either cold or warm stand‐by. Numerical examples are given for several life time and repair time distributions. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 483–498, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10025     

基于可视化仿真的高炮系统服务概率分析技术

服务概率是高炮系统作战效能的一个重要指标,同时也是合理配置防空兵器的重要参考依据。以排队论为基础的高炮系统服务概率数学模型及数值仿真技术已经比较成熟,但是其仿真过程不够直观形象。通过数据传递,在数值仿真的基础上建立了视景仿真系统,分析了系统的整体框架以及工作流程。在基于Unity3D的三维视景环境中,以真实的仿真数据来驱动模型运动,实现了目标航迹模拟以及目标信息的实时获取,再现了高炮系统的服务过程与射击效果,为高炮系统作战效能评估提供重要参考。     

空间飞行器及其推进系统智能自治控制技术分析

空间飞行器及其推进系统由于系统本身的复杂性、工作环境的不确定性和未知性等,利用传统的现代控制理论与方法对其进行控制十分困难。文中深入分析了智能自治控制系统内涵、功能及其构成框架,解析了空间飞行器RemoteAgent智能自治控制系统的基本构成,对空间飞行器推进系统重构问题进行了应用分析,对研究和发展我国空间飞行器的智能自治控制系统有一定的借鉴作用。     

Decomposition-based approximation algorithms for the one-warehouse multi-retailer problem with concave batch order costs

We study the one-warehouse multi-retailer problem under deterministic dynamic demand and concave batch order costs, where order batches have an identical capacity and the order cost function for each facility is concave within the batch. Under appropriate assumptions on holding cost structure, we obtain lower bounds via a decomposition that splits the two-echelon problem into single-facility subproblems, then propose approximation algorithms by judiciously recombining the subproblem solutions. For piecewise linear concave batch order costs with a constant number of slopes we obtain a constant-factor approximation, while for general concave batch costs we propose an approximation within a logarithmic factor of optimality. We also extend some results to subadditive order and/or holding costs.     

An exact analysis of a joint production‐inventory problem in two‐echelon inventory systems

We consider a two‐echelon inventory system with a manufacturer operating from a warehouse supplying multiple distribution centers (DCs) that satisfy the demand originating from multiple sources. The manufacturer has a finite production capacity and production times are stochastic. Demand from each source follows an independent Poisson process. We assume that the transportation times between the warehouse and DCs may be positive which may require keeping inventory at both the warehouse and DCs. Inventory in both echelons is managed using the base‐stock policy. Each demand source can procure the product from one or more DCs, each incurring a different fulfilment cost. The objective is to determine the optimal base‐stock levels at the warehouse and DCs as well as the assignment of the demand sources to the DCs so that the sum of inventory holding, backlog, and transportation costs is minimized. We obtain a simple equation for finding the optimal base‐stock level at each DC and an upper bound for the optimal base‐stock level at the warehouse. We demonstrate several managerial insights including that the demand from each source is optimally fulfilled entirely from a single distribution center, and as the system's utilization approaches 1, the optimal base‐stock level increases in the transportation time at a rate equal to the demand rate arriving at the DC. © 2011 Wiley Periodicals, Inc. Naval Research Logistics, 2011