并行工程冲突管理的研究

研究了并行工程产品开发过程中冲突的产生和冲突管理的过程与特点,分析了冲突管理在并行工程实施环境中所起到的重要作用,提出了冲突管理的体系结构。在此体系结构的框架下,基于集成的观点通过采用冲突避免的综合技术,可有效地减少和避免协同设计环境下大量的冲突;通过采用冲突检测和解决技术,则可在设计过程中较早地发现冲突,将冲突解决在设计的初级阶段,避免冲突的传播,最大可能地降低冲突对工程的破坏性影响     

用软件来提高多核处理器性能的方法分析

分析了多核处理器的硬件体系结构,并分析了影响多核处理器性能的最关键两个因素:二级缓存的命中率和处理器线路的利用率。主要分析了如何通过软件方法来提升多核处理器的性能,也就是通过设计操作系统进程调度算法来实现。分析了如何提高上述两个因素的方法。使用这些方法可以将多核处理器的吞吐率提高27%~45%。     

Fast conflict detection using probability flow

Probabilistic conflict detection has recently attracted much attention from researchers due to its importance in safe automated transport systems; however, current methods struggle to accurately calculate in real-time the probability of conflict for complex vehicle maneuvers in cluttered environments. We present a formulation for the general probabilistic conflict detection problem using the flow rate of conflict probability at the boundary of a conflict zone. For Gaussian distributed vehicle states, we then derive a tight upper bound for the probability of conflict over a time period, which can be calculated in real-time using adaptive numerical integration techniques. We present two examples to illustrate the performance of this method: the first example shows that this method is very efficient for simple environments and the second example shows that this method can calculate the conflict probability upper bound in real-time even for complex vehicle maneuvers in cluttered environments.     

The Optimizing QoS Miss Rate Scheme for the Data Centers

1IntroductionThe third-party services are hosted on the data cen-ters where the service owner pays rent for server re-sources,and in return,the service is provided guaran-tees on sufficient resources to meet service Quality ofService(QoS)requirement.In th…     

基于Chinese Wall安全策略的职责分离模型

职责分离是一个系统最基本的防止欺骗和错误的手段。该文在Chinese Wall安全策略的基础上，实现了一种基于历史记录的职责分离模型，通过跟踪用户的历史权限记录来决定用户当前分配的权限从而实现职责分离，并对其进行了形式化描述和分析，证明其满足职责分离安全原理。该模型继承了Chinese Wall策略和职责分离安全原则的优点，能够提供更加完善的访问控制策略。     

基于Oracle10g的分布式环境下的高级复制研究

该文以分布式数据库应用为背景,介绍了运用Oracle高级复制技术实现远程信息分布式处理的方案;详细论述了与高级复制相关的知识,以及复制中冲突的解决方法,最后针对高级复制的常见形式给出了实际的方案.     

局域网IP地址非法使用解决方案

随着互联网的普及，用户管理和安全管理问题逐渐凸现出来。其中比较典型的是IP地址非法使用的问题。本文就局域网内解决IP地址冲突问题作一点分析，并提出一些实际解决方案。     

导弹脱靶量测量方法研究

介绍了导弹脱靶量测量的几种方法,分析了每种方法的测量原理、特点、测量精度和适用范围.     

Easy concurrency

Advances in technology raise expectations. As far as software engineering is concerned, the common expectation is that coding and deploying applications is going to be simple. It seems, though, that software engineering is not getting easier, and the complexity moves to an application domain. One of the sources of complexity is an application concurrency. It is not an uncommon development practice that concurrency and transaction management in multi-user, multi-threaded, event-driven applications are postponed until after most of the required functionality is implemented. This situation has various explanations. On the one hand, business logic may require access and modification of large sets of inter-connected application objects. On the other, testing and stress-testing of this logic becomes possible only at advanced stages of product development. At these stages, increasing lock granularities may appear to be less "expensive" than debugging race conditions and deadlocks. Coarse-grained locking has, of course, an adverse effect on application scalability. Declaring rules of concurrency outside of the application may solve part of the problem. This paper presents an approach allowing developers to define concurrency in application-specific terms, design it in the early stages of development, and implement it using a documented API of the concurrency engine (CE). Simple notation makes it possible to record concurrency specifications in terms of application operations, relationships between application resources, and synchronization conflicts between operations. These concepts are demonstrated on examples. The final sections include the CE UML diagram, notes on API usage, and performance benchmarks. Published online: 25 July 2001