一种基于自适应复制的多Agent容错模型

为了构造和部署大规模的多agent系统,人们必须找到并解决其基本问题,其中之一就是可能存在的局部性系统故障。这也就意味着,容错对于大规模多agent系统来说,是一个无法回避的主题。文中讨论了这类问题并且提出了一种多agent系统的容错方法。最先的想法是将复制策略运用到agent中,对处于危急状态的agent进行复制从而避免系统故障,但是由于agent的危急性会在执行过程中演变,并且agent的可用资源是绑定的,所以需要动态以及自动地调整agent的复制体个数,从而最大化它们的作用和可靠性。文中将描述评估某个agent危险性的方法以及相关机制,并且决定使用何种策略(如:主动复制,被动复制)以及如何将其参数化(如:复制的个数)。     

一种基于复制组管理的移动agent容错模型

可靠性是影响目前移动agent应用扩展的一个关键问题之一,现有的分布式系统的容错方法不能完全照搬,该文提出一种基于复制组管理的移动agent容错模型ReGFatoM,通过改进已有的阶段构建模式以及加强复制组管理来提高系统的可靠性,实验表明,ReGFatoM能够有效解决诸如“只一次”执行、阻塞、网络分割等容错问题,而且具有模块化、效率高的优点。     

多agent分层强化学习在数据定位中的应用研究

为了在领域文本中实现数据定位,将文本视为环境,针对文本环境中存在的动态性以及不确定性等问题,提出了基于多agent分层强化学习的数据定位方法。该方法利用分层结构的特点,将系统任务分解为多个子任务,个体agent分别对对应子任务学习,以此将策略更新限制在规模较小的局部空间;同时利用多agent系统中单agent与系统远期目标的同一性,引入策略协调机制,通过agent之间交换信息来发现趋势性信息,并利用shaping技术,将在线获取的动态知识对各个agent进行趋势性启发,加快agent的收敛速度。将该方法应用于司法领域的判决文书上,实验结果表明：该方法能够在大规模复杂未知的文本环境中对目标数据进行高效准确定位,平均准确率与◢F◣值能够达到96.6%和98.2%,且具有较好的收敛速度。因此可以看出,该方法能够很好地在领域文本中实现数据定位,具有较大的理论以及实际意义。     

一种多agent的并行认知模型及应用

agent认知模型是多agent系统研究的基础。该文抓住多agent系统的社会行为特性,构建了动态的多agent系统模型。它可以动态地调整系统agent的个数,增强系统的求解问题的能力,整个系统随着问题求解的增多更加稳定。并且在构建动态多agent系统的基础上给出了多agent系统并行认知模型及其相关概念,并把该模型应用于问题求解。     

纠错码拜占庭容错Quorum中错误检测机制

摘要在大规模存储系统中,拜占庭存储节点的容错显得越来越重要。传统拜占庭Quorum通过复制可以容忍拜占庭失效,但是它们有两个主要缺点：低的存储空间利用率和静态quorum参数。我们提出纠错码拜占庭容错Quorum（Erasure-code Byzantine Fault-tolerance Quorum, E-BFQ）,E-BFQ采用纠错码作为冗余策略,可以提供高可靠性,同时比复制占用更少存储空间。通过客户端读／写操作和管理器诊断操作,E-BFQ可以检测拜占庭节点,动态调整系统规模和故障闽值。结果显示本文方法可以达到动态调整的目的。     

非通讯多Agent协作在RoboCup中的应用

智能体的行为预测是多智能体系统中的一个具有挑战性的问题。根据多agent系统（MAS）中的研究，为了提高进攻的速度，文中将一种新的合作策略引入到机器人足球中。首先，介绍了MAS的特点。同时，引入了一种agent削减算法来进行行为决策。进一步，调整了涉及到的agent的数目，在非通讯情况下实现了球员之间的协作。以后工作的重点是增加对对手的建模，以期提高进攻的成功率。     

基于多agent系统的大规模无人机集群对抗

本文将多agent系统引入到大规模无人机集群对抗决策系统中,给出了基于多agent系统的大规模无人机集群对抗决策方法.将机群中的每个无人机视为一个独立agent,建立了无人机运动模型,为无人机设计了独立的个体行为集,并针对每种行为给出了决策方法.通过每个个体无人机对其邻域环境的作用,涌现出宏观的集群对抗(作战)效果.使用MATLAB仿真软件对所设计的大规模无人机集群对抗方法进行了仿真,验证了所设计的基于多agent系统的大规模无人机集群对抗决策方法的有效性.     

DRE中基于半主动复制的实时CORBA应用

针对实时CORBA与容错CORBA模型融合在分布式实时嵌入式系统(DRE)中存在的问题,提出基于半主动复制策略的容错模型,应用到DRE中并进行相关测试。实验结果表明,采用半主动复制策略的模型相对其他复制策略可更好地支持实时系统,并能在保证实时要求的前提下为系统提供容错支持。     

基于多agent的移动数据库事务级同步复制模型研究

针对移动数据库中的同步复制问题,将多agent技术和事务结果集引入到事务级同步复制中,提出了基于多agent的移动数据库事务级同步复制模型.该模型与现有模型相比,具有如下主要特点:a)提高了系统可扩充性;b)减少了移动设备及网络资源占用;c)设计了一系列针对恶劣网络环境的同步策略.实验结果验证了模型的优良性能和恶劣环境下的可用性.     

一种多agent系统中死锁问题的解决策略

多agent系统注重agent之间的相互协作,但是在进行信息传递的过程中不可避免地会出现死锁。文章针对这一问题,结合文献[1]的有关思想,对死锁产生的条件进行了分析,讨论了死锁过程中可能出现的各种情况,利用个体agent的行为的独立性的以及多agent之间的相互依赖关系,采用消息传递和信息存储数据链等技术给出了死锁预防策略以及死锁消除策略,从而有效地对死锁情况进行预防和消除。     

A color object recognition scheme: application to cellular sorting

This paper presents a color object recognition scheme which proceeds in three sequential steps: segmentation, features extraction and classification. We mainly focus on the first and the third steps here. A color watershed using global and local criteria is first described. A color contrast value is defined to select the best color space for segmenting color objects. Then, an architecture of binary neural networks is described. Its properties relies on the simplification of the recognition problem, leading to a noticeable increase in the classification rate. We conclude with the abilities of such a recognition scheme and present an automated cell sorting system. Received: 15 June 2001 / Accepted: 1 July 2002 Published online: 23 April 2003 Correspondence to: O. Lezoray (e-mail: Olivier.Lezoray@info.unicaen.fr)     

Priority assignment in real-time active databases

Active databases and real-time databases have been important areas of research in the recent past. It has been recognized that many benefits can be gained by integrating real-time and active database technologies. However, not much work has been done in the area of transaction processing in real-time active databases. This paper deals with an important aspect of transaction processing in real-time active databases, namely the problem of assigning priorities to transactions. In these systems, time-constrained transactions trigger other transactions during their execution. We present three policies for assigning priorities to parent, immediate and deferred transactions executing on a multiprocessor system and then evaluate the policies through simulation. The policies use different amounts of semantic information about transactions to assign the priorities. The simulator has been validated against the results of earlier published studies. We conducted experiments in three settings: a task setting, a main memory database setting and a disk-resident database setting. Our results demonstrate that dynamically changing the priorities of transactions, depending on their behavior (triggering rules), yields a substantial improvement in the number of triggering transactions that meet their deadline in all three settings. Edited by Henry F. Korth and Amith Sheth. Received November 1994 / Accepted March 20, 1995     

Mariposa: a wide-area distributed database system

The requirements of wide-area distributed database systems differ dramatically from those of local-area network systems. In a wide-area network (WAN) configuration, individual sites usually report to different system administrators, have different access and charging algorithms, install site-specific data type extensions, and have different constraints on servicing remote requests. Typical of the last point are production transaction environments, which are fully engaged during normal business hours, and cannot take on additional load. Finally, there may be many sites participating in a WAN distributed DBMS. In this world, a single program performing global query optimization using a cost-based optimizer will not work well. Cost-based optimization does not respond well to site-specific type extension, access constraints, charging algorithms, and time-of-day constraints. Furthermore, traditional cost-based distributed optimizers do not scale well to a large number of possible processing sites. Since traditional distributed DBMSs have all used cost-based optimizers, they are not appropriate in a WAN environment, and a new architecture is required. We have proposed and implemented an economic paradigm as the solution to these issues in a new distributed DBMS called Mariposa. In this paper, we present the architecture and implementation of Mariposa and discuss early feedback on its operating characteristics. Edited by Henry F. Korth and Amith Sheth. Received November 1994 / Revised June 1995 / Accepted September 14, 1995     

IEC101/104规约在生态小水电一体化LCU中的应用

随着电力系统自动化与计算机网络通讯的不断发展,远动规约也在不断变化和发展,根据国际电工委员会制定的IEC60870-5-101和IEC60870-5-104远动规约,我国已经制定了相应的配套标准DL/T634-1997和DL/T634.5104-2002。其中IEC-60870-5-104作为采用标准传输协议子集的IEC60870-5-101的网络访问。文章讨论了采用IEC60870-5-101/104的必要性,介绍了一体化LCU的通讯结构,详细叙述了规约在生态小水电一体化LCU中的通讯实施过程,说明IEC60870-5-101/104两个国际标准,是能满足各种数据类型的传输和保证通信可靠性的方案,给通信数据的处理带来极大的方便。     

面向对象测试技术的研究与应用

面向对象的测试技术是面向对象开发方法的一个重要方面，它对软件质量和软件重用至关重要。本文描述了有关面向对象测试的一些关键问题，提出了一种面向对象的测试方法，给出了利用Rational公司的测试工具TestMate对C＋＋程序进行面向对象测试的样例。     

统计分析在系统级故障诊断中的应用

本文探讨统计分析在系统级故障诊断中的应用,提出两个概率诊断模型,讨论了给出的两个模型的测试算法及有关测试数据的统计推断。     

View-based navigation using an omniview sequence in a corridor environment

View- and appearance-based approaches have recently been attracting the interest of those involved in computer vision research. We have already proposed a visual view-based navigation method using a model of the route called the ”view sequence,” which contains a sequence of front views along a route memorized in the recording run. In this paper, we firstly apply the omnidirectional vision sensor to our view-based navigation method and propose an extended model of a route called the ”omniview sequence.” Secondly we propose a map named the ”view-sequenced map” which represents an entire corridor environment in a building. A method for the automatic acquisition of a view-sequenced map based on the exploration in a corridor using both stereo and omnidirectional vision is also described. Finally experimental results of the autonomous navigation and the map acquisition are presented to show the feasibility of the proposed methods. Correspondence to: Y. Matsumoto (e-mail: yoshio@is.aist-nara.ac.jp)     

Road feature detection and estimation

Crosswalks and stair-cases are useful road features for outdoor navigation. In this paper, crosswalks and stair-cases are detected by looking for groups of concurrent lines, and edges are then partitioned using intensity variation information. To distinguish them, three methods are developed to estimate the pose: a homography search approach using an a priori model, and finding the normal using the vanishing line computed from equally spaced lines and likewise with two vanishing points. These algorithms, with error analysis carried out, have been applied to real images with promising results, and they are also useful in other shape-from-texture applications. Received: 20 January 2001 / Accepted: 5 October 2002 Published online: 23 April 2003 Correspondence to: S. Se (e-mail: sse@mdrobotics.ca)