Facility location models for immobile servers with stochastic demand

This paper presents several models for the location of facilities subject to congestion. Motivated by applications to locating servers in communication networks and automatic teller machines in bank systems, these models are developed for situations in which immobile service facilities are congested by stochastic demand originating from nearby customer locations. We consider this problem from three different perspectives, that of (i) the service provider (wishing to limit costs of setup and operating servers), (ii) the customers (wishing to limit costs of accessing and waiting for service), and (iii) both the service provider and the customers combined. In all cases, a minimum level of service quality is ensured by imposing an upper bound on the server utilization rate at a service facility. The latter two perspectives also incorporate queueing delay costs as part of the objective. Some cases are amenable to an optimal solution. For those cases that are more challenging, we either propose heuristic procedures to find good solutions or establish equivalence to other well‐studied facility location problems. © 2003 Wiley Periodicals, Inc. Naval Research Logistics, 2004.     

基于小波系数相关性的图像隐写分析

提出了一种新的针对空域图像隐写的盲检测方法。利用互信息分析秘密信息嵌入对图像小波系数在尺度方向和空间方向相关性的影响,使用马尔可夫模型挖掘小波系数层内和层间相关性,提取转移概率矩阵作为特征,以支持向量机（SVM）作为分类器。针对LSB匹配和随机调制隐写算法。实验表明,本方法能有效检测到未经JPEG压缩过的含密图像。     

对金门战役“三不打”的考证

自20世纪80年代起,有关金门战役中第三野战军副司令员粟裕曾有过"三不打"的指示,引起部分军史研究者和民间史学爱好者的关注。此后,几乎所有关于金门战役的著述都或多或少、或直接或间接地提到了所谓的"三不打"。本文用史料分析、逻辑分析相结合的方法,对此问题进行了考证。结论是,此说属于"孤证",虽然无法证实其不存在,但更缺乏支持其存在的权威史料。     

新中国成立后毛泽东国防工程建设思想探析

新中国成立后,国防工程建设成为巩固国防的重要组成部分.毛泽东从战略高度,对国防工程建设进行精心筹划,做出一系列重大决策和指示,指导中国国防工程体系的构建,保证新中国战备与作战任务的完成,并在支援国家经济建设中发挥重要作用.本文从国防工程建设的基本着眼点、主要内容、基本原则等方面,对新中国成立后毛泽东国防工程建设思想进行初步研究.     

基于多资源点的装备应急器材调度决策模型

针对装备应急器材调度决策问题,从调度路径优化和调度计划分配2个方面,研究了其多目标优化模型的构建。将资源点划分为若干级别来确定资源点选取的优先次序,通过先求解资源点与需求点之间的最优路径,后求解器材资源分配量的思路,建立了装备应急器材调度决策的广义最优路径模型和运输模型,采用改进的Dijkstra算法对模型进行求解,仿真结果表明:所构建的决策模型及算法是有效的。     

中隔板对单洞双层隧道抗震性能的影响

单洞双层隧道是一种具有广阔应用前景的地下结构形式,大高跨比及中隔板约束使其拥有独特的力学特性。为了给单洞双层隧道的结构抗震优化设计提供依据,以伏龙坪单洞双层隧道为背景,利用FLAC3D软件,采用动力时程分析法研究中隔板位置对单洞双层隧道抗震性能的影响,并与静力分析结果进行比较。结果表明:中隔板的使用让双层隧道的抗震性能大幅提升,无中隔板时的边墙动力水平相对位移幅值较有中隔板时放大2.9~3.4倍;边墙动力水平相对位移幅值可以作为评价衬砌结构动力反应的依据;受动力作用,衬砌位移、应力都会有显著放大;静力作用与动力作用时,中隔板的最佳位置不同。     

基于MDA的MARTE模型形式化转换

非形式化/半形式化模型到形式化模型之间的转换是当前软件工程领域的研究热点。根据异构模型转换,提出了基于MDA的MARTE模型到Object-Z规约之间的转换方法。针对Object-Z在实时领域表达能力不足的问题,首先扩展Object-Z元模型;然后在MDA的元元模型体系下,定义了MARTE元模型和扩展的Object-Z元模型之间的转换规则。MARTE模型可以重用这些转换规则以实现到Object-Z形式化描述之间的转换,进而可以对模型进行形式化验证;最后通过一个实例使用该方法完成模型转换,具体说明了转换规则的应用。     

多相滤波结构的信道化接收机设计

根据现代电子侦察接收机所侦收信号的具体要求,文章讨论了信道化数字接收的可行性方案。探讨了信道划分的具体方式以及合理的信道化设计方案,研究了多相滤波结构的信道化模型及后续的信号检测方法,最终在单片FPGA上,设计实现了多相滤波结构的信道化接收机。在一定信噪比(SNR)的条件下,利用该结构的信道化接收机可以处理多路同时到达信号,并及时获得脉冲描述字(PDW)。该系统结构简单,便于硬件实现,测量速度快、精度高。满足对脉冲信号参数测量高精度、实时性的要求。     

Service design at diagnostic service centers

We study a service design problem in diagnostic service centers, call centers that provide medical advice to patients over the phone about what the appropriate course of action is, based on the caller's symptoms. Due to the tension between increased diagnostic accuracy and the increase in waiting times more in‐depth service requires, managers face a difficult decision in determining the optimal service depth to guide the diagnostic process. The specific problem we consider models the situation when the capacity (staffing level) at the center is fixed, and when the callers have both congestion‐ and noncongestion‐related costs relating to their call. We develop a queueing model incorporating these features and find that the optimal service depth can take one of two different structures, depending on factors such as the nurses' skill level and the maximum potential demand. Sensitivity analyses of the two optimal structures show that they are quite different. In some situations, it may (or may not) be optimal for the manager to try to expand the demand at the center, and increasing skill level may (or may not) increase congestion. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2012     

双重系统加密研究: 获得完全安全的IBE及其扩展

双重系统加密技术首先由Waters提出,是用于构造完仝安全的基于身份的加密(IBE)及其扩展方案的有力方法.针对完全安全方案的构造,研究了双重系统加密技术并提出了一个完全安仝方案的通用构造方法,即将一个利用双重系统加密的IBE方案与一个普通的方案相结合,得到一个新的可以利用双重系统加密证明安全的方案.在通用构造的基础上提出了一个实例,该实例是一个基于层级身份的加密( HIBE)方案,具有常密文长度.该方案比Waters提出的双重系统加密HIBE方案更高效,并且在判定BDH假设和判定线性假设下证明是完全安全的.