试论企业信息安全的开放式标准解决方案

本文讨论了企业信息安全解决方案。从身份验证和存取控制、消息发布和工作流、电子商务、安全管理和任务控制管理、开发启用安全性的应用等五个方面论述企业网络的安全体系结构。     

A fast and robust bulk-loading algorithm for indexing very large digital elevation datasets II. Experimental results

The spatial indexing of eventually all the available topographic information of Earth is a highly valuable tool for different geoscientific application domains. The Shuttle Radar Topography Mission (SRTM) collected and made available to the public one of the world's largest digital elevation models (DEMs). With the aim of providing on easier and faster access to these data by improving their further analysis and processing, we have indexed the SRTM DEM by means of a spatial index based on the kd-tree data structure, called the Q-tree. This paper is the second in a two-part series that includes a thorough performance analysis to validate the bulk-load algorithm efficiency of the Q-tree. We investigate performance measuring elapsed time in different contexts, analyzing disk space usage, testing response time with typical queries, and validating the final index structure balance. In addition, the paper includes performance comparisons with Oracle 11g that helps to understand the real cost of our proposal. Our tests prove that the proposed algorithm outperforms Oracle 11g using around a 9% of the elapsed time, taking six times less storage with more than 96% of page utilization, and getting faster response times to spatial queries issued on 4.5 million points. In addition to this, the behavior of the spatial index has been successfully tested on both an open GIS (VT Builder) and a visualizer tool derived from the previous one.     

面向战术飞机任务推演的威胁空间分析

根据战术飞机任务推演的特殊需求,文中提出了快速、逼真、交互式的威胁空间分析方法.首先介绍了战术飞机任务推演的概念,然后说明威胁空间分析的对象.在此基础上分别提出了武器系统威胁空间模型和非武器系统威胁空间模型:前者根据武器系统性能模型,考虑飞机雷达反射截面变化和地形遮蔽带来的影响,给出了探测类和歼毁类武器系统的威胁空间;后者给出了天气、地面碰撞、空中碰撞等威胁来源产生的威胁空间.接着提出威胁空间表达特有的方式,最后简单说明了推演系统的实现方法.     

基于可视化的安全态势感知

可视化技术为安全态势感知、大规模网络安全预警提供了十分现实的解决方法.人作为信息保障的一个重要环节,可视化技术提供了让人有效参与安全态势分析并做出正确决策的有效途经.文章重点研究了基于业务影响度进行安全态势评估的方法,并提出多种3D可视化模型进行相关数据的分析和展现,从不同的角度加强人对安全态势的感知能力.最后给出构建安全感知系统所经常采用的体系结构和数据流程.     

Evaluation of full and degraded mission reliability and mission dependability for intermittently operated, multi-functional systems

Availability is one of the metrics often used in the evaluation of system effectiveness. Its use as an effectiveness metric is often dictated by the nature of the system under consideration. While some systems operate continuously, many others operate on an intermittent basis where each operational period may often involve a different set of missions. This is the most likely scenario for complex multi-functional systems, where each specific system mission may require the availability of a different combination of system elements. Similarly, for these systems, not only is it important to know whether a mission can be initiated, it is just as important to know whether the system is capable of completing such a mission. Thus, for these systems, additional measures become relevant to provide a more holistic assessment of system effectiveness. This paper presents techniques for the evaluation of both full and degraded mission reliability and mission dependability for coherent, intermittently operated multi-functional systems. These metrics complement previously developed availability and degraded availability measures of multi-functional systems, in the comprehensive assessment of system effectiveness.     

地面测控任务规划调度的时间窗口约束研究

随着航天技术飞速发展,空间任务日趋复杂化,多个实验任务之间的协作加强,同时任务对空间环境的条件要求也越来越严格,对地面测控系统提出了更高的要求,是规划调度亟待解决的问题。本文在分析空间任务时序关系以及试验条件的基础上,将复杂空间任务规划调度问题转化为时间窗口编排问题,并提出了一种加速算法,提高了启发式算法求解效率,同时为解决空间任务规划提供了一种思路。通过仿真试验,初步证明了加速算法的有效性。     

Optimal sequencing of warm standby elements

Warm standby redundancy has been used as an effective design technique for improving the reliability of a system while achieving the compromise between restoration cost and operation cost of standby elements. This paper considers the optimal standby element sequencing problem (SESP) for 1-out-of-N: G heterogeneous warm-standby systems. Given the desired redundancy level and a fixed set of element choices, the objective of the optimal system design is to select the initiation sequence of the system elements so as to minimize the expected mission cost of the system while providing a certain level of system reliability. Based on a discrete approximation of time-to-failure distributions of the system elements, the system reliability and expected mission cost are evaluated using an iterative procedure. A genetic algorithm is used as an optimization tool for solving the formulated SESP problem for 1-out-of-N: G warm-standby systems with non-identical elements. As illustrated through examples, results generated using the suggested methodology can facilitate the system reliability versus cost trade-off study, which can further assist in the decision making about the best standby policy for fault-tolerant system designs.     

基于粒度计算和面向使命的组织适应性设计方法

介绍了面向使命的组织和组织设计,讨论了组织的适应性设计问题和组织适应性的代价。在此基础上提出了基于粒度计算的组织适应性设计方法,设计过程包括3个阶段：任务集和平台集粒化阶段、粒内规划阶段和决策分层阶段;并给出了平台集粒化的具体方法。案例分析表明本文的方法具有较好的性能。