KISO:一种基于本体论的集成知识系统设计

我们注意到不同的应用背景,编程语言,建模工具及网络协议及应用及用户间实现互操作的主要问题。为了解决基于知识的复杂求解问题,必须考虑系统的互操作性。本文提出一种基于体论的设计方案,从集成基础和集成实现两个方面来设计集成企业知识系统。     

域间路由系统动态演化模型研究

本文研究了因特网域间路由系统中各个自治系统在其成长消亡过程中需要考虑的各种影响因素,系统地阐述了自治系统之间商业关系的产生和变化,基于复杂系统的HOT理论建立了因特网域间路由系统的动态演化模型-CMV-HOT模型。本模型通过对域间路由系统的内部规律和外在表现的分析,考虑了AS间商业关系、不同AS的类型、连接约束等多种条件,从复杂系统的角度对域间路由系统的演化过程进行模拟。通过与真实BGP路由表数据的比较,说明CMV-HOT模型具有很高的准确性和实用价值。     

多域环境下安全互操作研究

基于角色的访问控制(RBAC)实现域间互操作的访问控制策略主要是采取角色映射的方法。针对角色在域间映射过程中,没有考虑同一角色对不同域的作用程度和域与域之间互信级别不同的问题。提出角色映射阈值属性和域阈值属性的概念,一定程度上解决了同一角色对不同域的作用程度和域与域间信任级别不同的问题,为不同组织域间实现互操作实现更加细粒度的访问控制,进一步提高了域间互操作的安全性。     

域间流量工程与域内流量工程的比较

根据作用的范围不同，流量工程可分为域间流量工程与域内流量工程。域间流量工程与域内流量工程作用的范围不同，研究问题的侧重点和难度不同，但是它们具有通用的处理模型，并且二者是紧密联系和相互依存的。同时考虑域间流量工程与域内流量工程，才能保证研究问题的全面性与准确性。     

银行SNA多协议综合业务网络

中国工商银行江苏省分行由于其本身业务快速发展的需要,并且随着电话银行、企业银行、自助银行和银行证券互联等新应用系统逐步开始进入实际应用,加上大型机延伸工程的实施,以及工商银行总行综合业务处理系统即将全面推广,其自身的信息化工作面临着新的挑战。为了保证信息在各种平台、各个系统间的顺利流动,就必须要考虑不同平台的互联,即异构网的互联问题。所以如何将原有的IBM的系统网络体系结构(System Network Architectrue,SNA)与开放系统有机地结合在一起,是江苏省工行计算机网络建设过程中必须要考虑的问题。     

网络控制系统多参最优性能研究

针对网络控制系统最优性能问题,对最优控制器进行设计和分析。首先建立了具有时延和数据丢包的系统模型,然后考虑控制对象具有非最小相位(NMP)零点、不稳定极点的情形,采用互质分解、Youla参数化等方法,求出最优跟踪性能的表达式并给出完整证明。最后分别研究最优跟踪性能与NMP零点、不稳定极点、时延、数据丢包这些参数间的相互关系。仿真结果表明,考虑不同的参数耦合,跟踪性能变化不同。     

多用户正交频分复用加权比例公平调度

传统的正交频分复用(OFDM)调度进行资源分配时没有考虑用户间速率比例公平性。针对这一问题,提出了一种新的适合于混合业务的多用户OFDM系统比例公平调度方案,其用户队列承载混合类型业务。该方案在用户间速率成比例约束条件下最大化系统权重容量和;授予用户队列中不同类型的分组不同的权重因子,并通过权重因子计算用户的权重;在子载波分配时不仅定义了信道优先级因子,而且在用户间速率成比例公平约束条件下通过该因子为用户分配子载波;最后推导出一种线性的功率分配方式。仿真结果与分析显示,该方案可以较好地满足用户速率和业务时延的需求,且可以在有效提高系统容量的基础上,严格地保证用户容量公平性。     

自组网中一种增强分群稳定性的分群算法

在自组网中,MSWCA是考虑运动相关性的分群算法中在分群稳定性度量方面考虑得最全面的典型算法。针对MSWCA"只考虑群内稳定性,而忽视群间稳定性"的问题,提出一种增强分群稳定性的分群算法(CAECS)。该算法基于移动预测思想,综合考虑群内稳定性、群间稳定性和分群优化,通过调节权值使算法适用于不同的场景。仿真结果表明:当权值取值适当时,CAECS在分群稳定性和分群维护开销等性能指标上都要优于MSWCA。     

风险管理不只是信息安全

风险管理只遵循固定的信息安全标准与准则,是无法在任何环境中都应对自如的。金融和IT业间的分离是由于对风险的不同理解造成的。IT业倾向于从安全系统这个角度来考虑风险—控制管理系统以及遵从报表和最佳的程序。     

基于主题森林结构的对话管理模型

现有许多对话系统都是面向任务的,但很少考虑对话过程涉及的多主题、主题切换、主 题间的信息共享,以及不同信息重要程度不同等问题.该文提出基于主题森林结构的对话管理 模型,较好地处理了上述问题,能实现对话过程的混合主导.该模型能保证交互过程中对话内容 的一致性,对上下文的理解、对话控制和应答决策灵活自然.其推理机应用了多种与领域无关的 策略,具有较好的可移植性.     

An analysis of electronic-mail usage

Advances in information technology have set the pace for tremendous growth in the development of new computer-mediated channels of communication services and technologies. That these recent developments are fueled by technology might misleadingly suggest that the selection of a communication channel is largely based on technological criteria. Communication technologies require multiple users and cannot be used successfully by one person acting alone. Therefore, problems may arise when users fail to consider their self-efficacy and/or fail to consider social factors related to communication channel use.The main purpose of this study was to establish a better measure and model for use in predicting and explaining electronic-mail systems as an example of computer-mediated communication technologies (CMCT) usage and choice. The results indicated that all of the eight hypotheses showed significant correlation between criterion and predictor variates, supported by different canonical functions. The objective of the study was achieved by showing that the proposed research model can explain and predict the individual and combined effects of user self-efficacy, technological characteristics, and social-influence perspectives on CMCT usage and choice.     

Preface

Networked sensing and control has attracted significant interest in recent years due to its wide applications. For example, sensor networks, especially wireless sensor networks, have found important applications in environmental monitoring, agriculture, building and industrial automation, machine condition monitoring, intelligent transportation systems, health care, surveillance, and defense. On the other hand, due to the flexibility and significant cost-saving, there has been an increasing trend for control systems to utilize digital communication networks for exchanging information between sensor and controller and/or controller and actuator, as well as between subsystems or systems sharing the same communication networks. Furthermore, networked multiagent systems, where the collective behavior of a system is realized through interactions among dynamically decoupled systems, have also been the focus of many recent research efforts. In networked systems, the network is an important component with constraints and uncertainties, such as the limited bandwidth, random transmission-delays, possible packet-losses, out-of-sequence measurements, etc. The uncertainties and constraints become more significant in wireless networks because of its limited resources of communication and computation, and the fading that changes the throughput of communication channels. As a result, there is an imperative need of new tools for analysis and synthesis, and new algorithms for control, estimation and decision-making, to take these uncertainties and constraints into consideration and handle the interplay among communication, computation and control. In the past few years, a lot of research efforts have been devoted to this field and significant advancement has been made. This special issue intends to reflect part of those achievements. Indeed, the special issue consists of 17 papers among which 8 discuss the control over communication networks, 1 investigates the traffic control in communication networks, 3 are concerned with multiagent systems, and 5 deal with wireless sensor networks. All papers were selected from numerous submissions and carefully reviewed.We hope that the special issue will promote the research interest in networked sensing, actuation and control systems, and foster new applications of networked systems. Special issue editors: Lihua Xie, Nanyang Technological University, Singapore. Frank L. Lewis, The University of Texas at Arlington, USA.     

A Group-Based Load Balance Scheme for Software Distributed Shared Memory Systems

Load balance is an important issue for the performance of software distributed shared memory (DSM) systems. One solution of addressing this issue is exploiting dynamic thread migration. In order to reduce the data consistency communication increased by thread migration, an effective load balance scheme must carefully choose threads and destination nodes for workload migration. In this paper, a group-based load balance scheme is proposed to resolve this problem. The main characteristic of this scheme is to classify the overloaded nodes and the lightly loaded nodes into a sender group and a receiver group, and then consider all the threads of the sender group and all the nodes of the receiver group for each decision. The experimental results show that the group-based scheme reduces more communication than the previous schemes. Besides, this paper also resolves the problem of the high costs caused by group-based schemes. Therefore, the performance of the test programs is effectively enhanced after minimizing the communication increased by thread migration.     

Topological analysis of a two coupled evolving networks model for business systems

In multi-agent systems, the underlying networks are always dynamic and network topologies are always changing over time. Performance analyses of topologies are important for understanding the robustness of the system and also the effects of topology on the system efficiency and effectiveness. In this paper, we present an example of a real-world distributed agent system, a digital business ecosystem (DBE). It is modelled as a two coupled network system. The upper layer is the business network layer where business process between different business agents happen. The lower layer is the underlying P2P communication layer to support communications between the agents. Algorithms for multi-agent tasks negotiation and execution, interaction between agents and the underlying communication network, evolutionary network topology dynamics, are provided. These algorithms consider the two network layers evolving over time, with effects on each other. Through a comprehensive set of discrete event simulation, we investigate the effects of different evolutionary principles inspired by random graph and scale-free network in complex network theory on the topological properties and performance of the underlying network. We also find several rules to design a resilient and efficient P2P network.     

分布式系统可靠性模型

文章首先给出分布式系统的一般描述;然后采用建立在图论、概率论及布尔代数基础上的网络分析法建立了分布式系统的可靠性模型,用以综合考虑系统拓朴结构、任务集、通讯路径集和处理单元集等对系统可靠性的影响;最后,针对二维TORUS网,给出了建模实例以及模型的有关应用。     

RoboNetSim: An integrated framework for multi-robot and network simulation

In networked multi-robot systems, communication plays a major role defining system’s dynamics and performance. Unfortunately, existing multi-robot simulators do not provide advanced communication models. Therefore, given the intrinsic unreliability of wireless communications, significant differences might be observed between simulation and real-world results.Addressing these issues, we present RoboNetSim, an integrated simulation framework for communication-realistic simulation of networked multi-robot systems. RoboNetSim integrates multi-robot simulators with network simulators. We present two model implementations based on ARGoS at the robotic side, and NS-2 and NS-3 as network simulators. We evaluate the framework in terms of accuracy and computational performance, showing that it can efficiently simulate systems consisting of hundreds of robots.Using the Stage simulator as an example, we also show the integration of a robotic simulator with RoboNetSim by only adapting robot controllers, without the need to adapt the general code of the simulator.Finally, we demonstrate the effects of communication on mobile multi-robot systems. We consider two different case studies: a distributed coordination and task assignment scenario, and a coordinated mobility scenario. We compare realistic network simulation with simplified communication models and algorithms, and we study the resulting behavior and performance of the multi-robot system and the impact of different parameters.     

A convex characterization of distributed control problems in spatially invariant systems with communication constraints

In this paper we consider the problem of distributed controller design in spatially invariant systems for which communication among sites is limited. In particular, the controller is constrained so that information is propagated with a delay that depends on the distance between subsystems—a structure we refer to as “funnel” causality. We show that the problem of optimal design can be cast as a convex problem provided that the plant has a similar funnel-causality structure, and the propagation speeds in the controller are at least as fast as those in the plant. As an example, we consider the case of the wave dynamics with limited propagation speed control.     

Streets of Byzantium: Network Architectures for Fast Reliable Broadcasts

A site broadcasting its local value to all other sites ina fault-prone environment is a fundamental paradigm in constructing reliable distributed systems. Time complexity lower bounds and network connectivity requirements for reliable broadcast protocols in point-to-point communication networks are well known. In this paper, we consider the reliable broadcast problem in distributed systems with broadcast networks (for example, Ethernets) as the basic communication architecture. We show how properties of such network architectures can be used to effectively restrict the externally visible behavior of faulty processors. We use these techniques to derive simple protocols that implement reliable broadcast in only two rounds, independent of the failure upper bounds.     

Adapting wave-front algorithms to efficiently utilize systems with deep communication hierarchies

Large-scale systems increasingly exhibit a differential between intra-chip and inter-chip communication performance especially in hybrid systems using accelerators. Processor-cores on the same socket are able to communicate at lower latencies, and with higher bandwidths, than cores on different sockets either within the same node or between nodes. A key challenge is to efficiently use this communication hierarchy and hence optimize performance. We consider here the class of applications that contains wave-front processing. In these applications data can only be processed after their upstream neighbors have been processed. Similar dependencies result between processors in which communication is required to pass boundary data downstream and whose cost is typically impacted by the slowest communication channel in use. In this work we develop a novel hierarchical wave-front approach that reduces the use of slower communications in the hierarchy but at the cost of additional steps in the parallel computation and higher use of on-chip communications. This tradeoff is explored using a performance model. An implementation using the reverse-acceleration programming model on the petascale Roadrunner system demonstrates a 27% performance improvement at full system-scale on a kernel application. The approach is generally applicable to large-scale multi-core and accelerated systems where a differential in communication performance exists.     

具有随机网络攻击的切换信息物理系统的事件触发控制（英文）

本文研究了随机网络攻击下切换信息物理系统的事件触发控制问题.将信息物理系统描述为一种切换线性系统形式.引入事件触发机制来节省系统资源和减轻网络负载,当误差超过给定阈值时传感器中的采样数据才通过通信网络传输到控制器中.考虑在传感器与控制器的通信网络中受到两种不同特征的随机网络攻击.在网络攻击和所设计的事件触发控制器下,建立了切换随机信息物理系统模型.利用模态依赖平均驻留时间方法构建了相应的切换信号.在设计的事件触发控制器和模态依赖平均驻留时间切换信号下实现了系统的均方指数稳定性,并给出了控制器增益.最后,通过实例验证了所得理论结果的有效性.