分布式视频点播系统的接入控制研究

Video on Demand(VoD)systems are considered as one of the most valuable services for the next generation broad-bandwidth Internet. To provide high-quality service, the VoD system must employ an admission control module to guarantee QoS, but there are still less research works having been made in this field, especially for distributed VoD systems. In this paper, we mainly focus on distributed admission control for VBR video streams in distributed VoD systems. We firstly discuss different approaches and then two admission control strategies are proposed with experimental comparisons. Our research is also further extended to resource assignment in distributed VoD systems. At the end of this article, we address issues in implementing distributed admission control.     

水源地分布式微机控制系统

介绍水源地微机控制系统的构成，功能，简述分布式自动控制系统的技术指标和移植特点及以系统投入运行后带来的经济效益。     

事件触发双模分布式预测控制

本文针对有界扰动作用下的线性离散大系统,提出了事件触发双模分布式预测控制设计方法.利用输入状态稳定性(input-to-state stability,ISS)理论建立了仅与子系统自身信息相关的事件触发条件.只有子系统满足相应的事件触发条件,才进行状态信息的传输和分布式预测控制优化问题的求解,并与邻域子系统交互最优解作用下的关联信息.当子系统进入不变集时,采用状态反馈控制律进行镇定,并与进入不变集的邻域子系统不再交互信息.分析了算法的递推可行性和系统的闭环稳定性,给出了扰动的上界.最后,通过车辆控制系统对算法进行仿真验证,结果表明,本文提出的方法能够有效降低优化问题的求解次数和关联信息的交互次数,节约计算资源和通信资源.     

微电网系统的分布式优化下垂控制

针对微电网系统运行成本最优化问题,提出一种分布式优化下垂控制策略.首先,基于一致性理论,给出了一种分布式经济调度算法.采用矩阵摄动理论,分析了经济调度算法的收敛特性.其次,基于分布式优化调度解,设计一种新的分布式优化下垂控制器.在满足供需平衡以及各个发电单元运行约束的条件下,控制策略使得微电网系统运行成本最低.同时,提出的控制策略能够保证孤岛微电网的频率稳定在额定值.最后,通过仿真实例,验证了分布式优化下垂控制策略的有效性.     

一种用于工厂动力控制的分布式微机监控系统

本文主要针对工厂设备动力控制的分布式微机监控系统的主要功能,系统的组成结构,系统的软件设计以及系统分析、异种微机间的通讯规程设计等进行了论述。     

复杂大系统的集成控制

复杂大系统的集成控制李人厚（西安交通大学系统工程所７１００４９）１引言随着科学技术的发展，生产系统的规模越来越大，形成了复杂的大系统．象电力系统，化工系统，军事指挥系统，柔性制造系统等等都是典型的复杂大系统．所谓复杂性主要是指受控对象模型的不确定性；...     

切换非线性系统的分布式模型预测控制

针对一类具有预先指定切换序列的切换非线性系统,研究了具有通信信道干扰和时滞测量的分布式模型预测控制问题.在每个子系统都存在镇定控制器的假设下,利用基于Lyapunov函数的模型预测控制器设计了分布式模型预测控制器,并给出了闭环切换非线性系统最终有界的充分条件.最后,通过仿真结果表明了分布式模型预测控制策略的有效性.     

现场总线系统分布式智能预测控制的实现

对于采用现场总线系统控制的复杂对象,应用智能预测控制的方式对其进行分布式控制,将现场总线的特点与智能预测控制方法相结合,使各子系统之间的参数以及控制动作协调一致,以实现对整个系统的优化控制．提出了在现场总线系统中构建该方法的步骤,并给出了一个采用该控制方法获得较好控制效果的具体实例。     

基于分布式控制的计算机教学刷卡系统

计算机教学刷卡系统用于计算机实验室教学管理，具有很高的实用性与现实意义。本文从发展、应用、结构和效果几方面．并结合实际使用叙述了该系统的基本特点。     

基于Browser／Server的分布式诊断系统

本文针对大规模并行计算机系统设计了基于Browser/Server的诊断系统,并对该系统的结构、通讯机制、诊断策略进行了详细的描述。     

减少离散大系统两级镇定控制的保守性

The aim of this paper is to propose a new algorithm for multilevel stabilization of large scale systems. In two-level stabilization method, a set of local stabilizers for the individual subsystems in a completely decentralized environment is designed. The solution of the control problem involves designing of a global controller on a higher hierarchical level that provides corrective signals to account for interconnections effect. The principle feature of this paper is to reduce conservativeness in global controller design. Here, the key point is to reduce the effect of interactions instead of neutralizing them. In fact, unlike prior methods, our idea does not ignore the possible beneficial aspects of the interactions and does not try to neutralize them.     

信息大系统的信息集成结构模型设计与实现

该文根据信息系统集成中信息集成的特点及主要内容,提出了一种基于Intranet／Internet的信息集成总体结构模型和信息集成分层结构模型,并给出了相应的应用设计和实现的例证。     

Fundamentals of Implementing Real-Time Control Applications in Distributed Computer Systems

Automatic control applications are real-time systems which pose stringent requirements on precisely time-triggered synchronized actions and constant end-to-end delays in feedback loops which often constitute multi-rate systems. Motivated by the apparent gap between computer science and automatic control theory, a set of requirements for real-time implementation of control applications is given. A real-time behavioral model for control applications is then presented and exemplified. Important sources and characteristics of time-variations in distributed computer systems are investigated. This illuminates key execution strategies to ensure the required timing behavior. Implications on design and implementation and directions for further work are discussed.     

多组时滞大型控制系统的镇定

给出了由无时滞线性定常闭孤立控制子系统的渐近稳定性推出多组时滞线性定常闭环大型控制系统的渐近稳定性的充分条件，并说明了所得结果可以推广到多组时滞线性时变闭环大型控制系统与多组时滞线中立型定常（或时变）闭环大型控制系统，所得结果改进了前人的结果，通过参数镇定域的比较知，可使参数镇定域扩大为原来的６倍。     

利用细化RBAC模型实现大型信息系统的安全访问控制

基于角色的访问控制是一种高效安全的访问控制机制,但是传统的RBAC模型没有提出根据单位特征、功能特征和数据特征来细化控制角色指派的方法。本文结合RBAC模型思想和大型企业信息系统的实际需求对RBAC模型进行改进,在单位、功能、数据等维度对模型进行了细化,并给出了实例应用,有效地解决了大型企业信息系统的安全访问控制难以细化的问题。     

利用细化RBAC模型实现大型信息系统的安全访问控制

基于角色的访问控制是一种高效安全的访问控制机制，但是传统的KBAC模型没有提出根据单位特征、功能特征和数据特征来细化控制角色指派的方法。本文结合KBAC模型思想和大型企业信息系统的实际需求对KBAC模型进行改进，在单位、功能、数据等维度对模型进行了细化。并给出了实例应用，有效地解决了大型企业信息系统的安全访问控制难以细化的问题。     

Building Large,Complex, Distributed Safety-Critical Operating Systems

Safety-critical systems typically operate in unpredictable environments. Requirements for safety and reliability are in conflict with those for real-time responsiveness. Due to unpredictable environmental needs there is no static trade-off between measures to accommodate the conflicting objectives. Instead every feature or operating system service has to be adaptive. Finally, for any design problem, there cannot be any closed-form (formal) approach taking care at the same time of (external) time constraints or deadlines, and synchronization requirements in distributed design. The reason is that these two aspects are causally independent. - In this situation we worked out a heuristic experimental, performance-driven and performance-based methodology that allows in an educated way to start with a coarse system model, with accurate logical expectations regarding its behavior. Through experiments these expectations are validated. If they are found to successfully stand the tests extended expectations and model features are generated for refining the previous design as well as its performance criteria. The refinement is done in such a way that the previous experimental configurations are extreme model cases or data profiles which both logically and experimentally are to reproduce the behavior of the previous modeling step. Thus the novel performance aspects or tendencies could then unambiguously be attributed to the influences of the refined model features. We termed this methodology Incremental Experimentation. As a general methodology it relies on a principle of comparative performance studies rather than on realistic data for narrow application ranges. The paper describes how we applied a 5-step design and refinement procedure for developing, analyzing, and evaluating our distributed operating system MELODY that exhibits novel services for supporting real-time and safety-critical applications in unpredictable environments. Experimental set-ups and theme-related findings are discussed in particular.     

一种小型集散控制系统的研制

介绍了一种小型集散控制系统在工程控制领域中的应用实例 ,给出了实现该系统的原理框图 ,并详细介绍了各部分的作用和具体实现技术     

大规模分布式仿真中实体分配策略研究

在大规模分布式仿真中,能否为数量众多的仿真实体合理指定其所在的宿主仿真机将直接影响系统性能。本文在文献[1]提出的实体分配评价指标以及仿真场景图划分代价表示的基础上,首先介绍了仿真场景图的递归对分,接着提出了两种实体分配算法：最大流量顶点归并法和最大可能收益顶点归并法。针对均匀分布、倾斜分布、聚集分布以及随机分布等各种实体分布类型,分别评测了各算法的配置结果和代价。评测结果表明,最大可能收益顶点归并法能得到较优结果,且执行速度快。     

基于大系统理论的分布式数据库系统设计与分析

在介绍了大系统控制理论及分布式系统特点的基础上,给出了一个大型分布式数据库系统的设计方案,详细描述了该方案中的系统功能结构,系统逻辑结构、系统控制模型及系统数据库设计等,并对系统性能进行了分析。