基于多层授权体制的档案全文检索系统设计与实现

档案资料不同于普通的信息资源,其在保密性和专属性上有较高的要求。研 究了在网络环境下建设数字档案全文检索系统时遇到的问题,分析了原有授权体制存在的 弊端,提出了一种基于角色、用户分离的多层授权体制,并在实际系统建设中应用此授权体 制,实现了高效的全文检索和安全、可靠、灵活的访问控制。     

亚超结合反舰导弹控制规律的选择与分析

针对现代海战的特点,分析了现代海战对反舰导弹的性能需求,提出了亚超结合反舰导弹是未来反舰导弹的发展方向。进一步分析了亚超结合反舰导弹对控制系统的要求,并对未来亚超结合反舰导弹控制系统控制规律的选取作了研究分析,最后提出了亚超结合反舰导弹设计的主要关键技术和应注意的几个问题。     

航空电子综合火控系统驾驶员操作程序(POP)仿真

驾驶员操作程序(POP)是航电综合设计最重要的顶层设计文件,其仿真对支持总体设计具有不可替代的作用。首先从整个航空火控系统的角度阐述了POP的组成及任务操作,然后介绍了POP仿真模型的建立方法和制作思路,并对某型飞机航电综合火控系统POP进行了仿真实现。其结果可用于评价飞机航电综合火控系统的POP操作逻辑关系的正确性。     

Fixed‐interval joint‐replenishment policies for distribution systems with multiple retailers and stochastic demand

We consider a distribution system consisting of a central warehouse and a group of retailers facing independent stochastic demand. The retailers replenish from the warehouse, and the warehouse from an outside supplier with ample supply. Time is continuous. Most previous studies on inventory control policies for this system have considered stock‐based batch‐ordering policies. We develop a time‐based joint‐replenishment policy in this study. Let the warehouse set up a basic replenishment interval. The retailers are replenished through the warehouse in intervals that are integer multiples of the basic replenishment interval. No inventory is carried at the warehouse. We provide an exact evaluation of the long‐term average system costs under the assumption that stock can be balanced among the retailers. The structural properties of the inventory system are characterized. We show that, although it is well known that stock‐based inventory control policies dominate time‐based inventory control policies at a single facility, this dominance does not hold for distribution systems with multiple retailers and stochastic demand. This is because the latter can provide a more efficient mechanism to streamline inventory flow and pool retailer demand, even though the former may be able to use more updated stock information to optimize system performance. The findings of the study provide insights about the key factors that drive the performance of a multiechelon inventory control system. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 60: 637–651, 2013     

Models for production planning under power interruptions

We present a robust optimization model for production planning under the assumption that electricity supply is subject to uncertain interruptions caused by participation in interruptible load contracts (ILCs). The objective is to minimize the cost of electricity used for production while providing a robust production plan which ensures demand satisfaction under all possible interruption scenarios. The combinatorial size of the set of interruption scenarios makes this a challenging problem. Furthermore, we assume that no probabilistic information is known about the supply uncertainty: we only use the information given in the ILC to identify an uncertainty set that captures the possible scenarios. We construct a general robust framework to handle this uncertainty and present a heuristic to compute a good feasible solution of the robust model. We provide computational experiments on a real‐world example and compare the performance of an exact solver applied to the robust model with that of the heuristic procedure. Finally, we include the operational impact of interruptions such as “recovery modes” in the definition of the uncertainty set. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Directional change‐point detection for process control with multivariate categorical data

Most modern processes involve multiple quality characteristics that are all measured on attribute levels, and their overall quality is determined by these characteristics simultaneously. The characteristic factors usually correlate with each other, making multivariate categorical control techniques a must. We study Phase I analysis of multivariate categorical processes (MCPs) to identify the presence of change‐points in the reference dataset. A directional change‐point detection method based on log‐linear models is proposed. The method exploits directional shift information and integrates MCPs into the unified framework of multivariate binomial and multivariate multinomial distributions. A diagnostic scheme for identifying the change‐point location and the shift direction is also suggested. Numerical simulations are conducted to demonstrate the detection effectiveness and the diagnostic accuracy.© 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

Robust shortest path problems with two uncertain multiplicative cost coefficients

We consider a robust shortest path problem when the cost coefficient is the product of two uncertain factors. We first show that the robust problem can be solved in polynomial time by a dual‐variable enumeration with shortest path problems as subproblems. We also propose a path enumeration approach using a K ‐shortest paths finding algorithm that may be efficient in many real cases. An application in hazardous materials transportation is discussed, and the solution methods are illustrated by numerical examples. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

分布式放大前传中继辅助多用户对等通信中的鲁棒波束成形

针对分布式放大前传中继辅助多用户对等通信系统研究了存在非理想信道状态信息(CSI)时的分布式中继网络(DRN)鲁棒波束成形设计问题。采用统计CSI误差模型,考虑了两种鲁棒优化问题:一是从公平性的角度出发在DRN总发送功率约束下实现多个目的节点间的信干噪比(SINR)平衡;另一是从有效性的角度出发在保证各个目的节点服务质量需求(SINR大于预设门限)约束下最小化DRN总发送功率。对问题的分析和建模表明,在多用户情况下,这两个问题都是难以求解的优化问题。通过引入半定松弛(SDR)思想,将上述两种优化问题转化为可利用内点法有效求解的半定规划(SDP)问题。最后通过仿真验证了所提设计的鲁棒性能。     

GETTING BETTER ALL THE TIME

Detect and Deter: Can Countries Verify the Nuclear Test Ban?, by Ola Dahlman, Jenifer Mackby, Svein Mykkeltveit, and Hein Haak. Springer, 2011. 279 pages, $129.     

Building the next nuclear community

This viewpoint takes stock of the changes in the strategic nuclear landscape in recent decades and reflects on its consequences on the policy community. It finds that the number and scope of issues have expanded considerably; they have manifested themselves in many more regions of the world; and they have become deeply politicized and polarized. The consequences have been twofold: the nuclear policy field has seen the development of an increasingly diverse expert community composed of highly specialized functionalists and regionalists, and it has become ever more divided into two entirely separate ideological camps—one that believes in deterrence, the other in disarmament. The stove-piping of expertise and the widening gap between deterrence and disarmament ideologies are immensely problematic because, in different ways, they stand in the way of the emergence of a better and safer nuclear future. Looking ahead, it is critical to “bust the silos of expertise” and to build bridges between the deterrence and disarmament ideological camps. Only such a community-building effort will help solve today’s and tomorrow’s nuclear challenges.