一种基于MPLS的Diff-serv模型的设计与分析

提出了一种新的基于MPLS的Diff-serv模型－扩展LSP模型，它较好地解决了可扩展性，支持所有PHB和支持多种数据链路层媒体这3个基于MPLS的骨干网IP QoS实现方案面临的关键问题，并且通过将扩展LSP模型与现有的3个模型进行分析比较，表明扩展LSP模型是一种基于MPLS的功能完善且可行的IP QoS模型。     

IP QoS的实现技术

IP网络的QoS技术是当前研究的热点问题.本文叙述了IntServ(综合服务模型)、DiffServ(区分服务模型)、IntServ与DiffServ结合的端到端QoS机制以及MPLS(多协议标签交换)等QoS实现方案,并对目前研究较多的MPLS的IP QoS实现进行了探讨.最后简单讲述了目前各种IP QoS实现技术的局限性,并探讨了未来发展的方向.     

MPLmS实现IP的服务质量

服务质量(Quality of Senice，QoS)保证是IP网发展的一个巨大挑战。尽管增加带宽能够改善因特网的服务质量，但仅限于目前“尽力而为”的服务模式．无法满足新应用的特点与需求。文章提出MPLmS(多协议标签波长交换)实现IP QoS的方案，探讨IP包格式与MPLmS格式的映射关系，使IP QoS能够通过MPLmS直接在IP over WDM网络上得到相应的传输服务保证。     

一种基于DiffServ的IP电话QoS实现方案

如何为IP网络中的业务提供QoS保证正成为lP技术所要解决的关键问题。文中基于Diffserv提出了一种IP电话QoS方案，并对其基本思想及实现方法作了详细介绍。该方案将不同的分组数据包设置成不同的优先级，其中系统控制分组数据包优先级最高，语音分组数据包次之，普通数据分组数据包最低，使得系统控制分组和语音分组数据包的平均等待时间缩短。研究结果表明，对不同数据包进行优先级设置是改善IP电话QoS的一种可行方法。     

Internet上IP QoS的研究

首先阐述了IP QoS的含义、技术指标，然后分析了IETF的两个基本模型和实现IP QoS的关键机制，最后对IP QoS的发展进行了展望。     

在ATM网络上MPLS的实现

多协议标记交换技术(MPLS)能在主干网上大大提高IP转发性能，并提供服务分类(CoS)及服务质量保证(QoS)。MPLS在现有的主干ATM网上可提供高性能的IP服务。该文主要介绍了MPLS技术，并讨论了在ATM网上实现MPLS所必须解决的一些关健技术。     

基于软交换技术的远程教育电视系统的实现

提出了一种在单向有线数字电视HFC网和IP网上采用软交换技术、IP技术的远程教育方法，并将该方法加以实现。通过软交换体系使HFC网和IP网能够互通互用,较好地解决了广播电视HFC网、IP网分别开展远程教育所带来的网络拥塞、时延、QoS保证及双向互动等不足，为远程实时教学提供了一种可行方案。     

基于DiffServ体系的IP网方案及QoS的技术

文章在一些研究成果的基础上,对IntServ/RSVP体系与DiffServ体系协议相结合的机制进行了探讨。进一步讨论了基于DiffServ体系的IP骨干网的两种管理方案,即动态管理方案和静态管理方案。通过分析得出结论,在基于DiffServ体系的控制环境下采用动态管理方案是实现QoS保证的最佳技术,由此提出了一种DiffServ/RSVP体系作为IP骨干网的方案,并对任意进出IP骨干网的IP分组按策略添加新分组头和按位判别法实现QoS保证的技术。     

下一代IP网的QoS和移动性结构

下一代IP网络将支持有不同QoS需求的应用和移动性能，主要介绍下一代IP网络实现QoS协议的概况，给出一个能将各种QoS和移动协议结合起来提供端－到－端QoS的实现结构。     

基于以太网的IP接入网络的QoS技术研究

接入网的QoS机制是实现NGN中端到端的QoS保证的重要因素，而以太网是最为主要的接入网技术。本文讨论了ITU NGN专题组NGNFG中关于基于以太网IP接入网络的QoS的控制体系结构的研究进展，在基于以太网IP接入网络的定义和参考模型中分析了基于以太网IP接入网络的QoS问题，本文阐述了基于以太网的IP接入网络的支持动态和每个会话控制的QoS控制过程和提出了有关的接口以及它们的需求。     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

法律信息库系统

本文分析了法律数据库的结构和特点，介绍了采用面向对象设计方法和超文本数据库技术开发和实现法律信息库系统将作为重要网络资源之一为不同用户进行法律咨询服务。     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

International Journal of Automation and Computing Table of Contents

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Information for authors

正SCIENCE CHINA Information Sciences(Sci China Inf Sci),cosponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China,and published by Science China Press,is committed to publishing highquality,original results of both basic and applied research in all areas of information sciences,including computer science and technology;systems science,control science and engineering(published in Issues with odd numbers);information and communication engineering;electronic science and technology(published in Issues with even numbers).Sci China Inf Sci is published monthly in both print and electronic forms.It is indexed by Academic OneFile,Astrophysics Data System(ADS),CSA,Cabells,Current Contents/Engineering,Computing and Technology,DBLP,Digital Mathematics Registry,Earthquake Engineering Abstracts,Engineering Index,Engineered Materials Abstracts,Gale,Google,INSPEC,Journal Citation Reports/Science Edition,Mathematical Reviews,OCLC,ProQuest,SCOPUS,Science Citation Index Expanded,Summon by Serial Solutions,VINITI,Zentralblatt MATH.     

Erratum to: Fast global kernel fuzzy c-means clustering algorithm for consonant/vowel segmentation of speech signal

正Erratum to:J Zhejiang Univ-Sci C(ComputElectron)2014 15(7):551-563doi:10.1631/jzus.C1300320The original version of this article unfortunately contained mistakes.Algorithm 6 should be as follows:Algorithm 6 FGKFCM-F clustering Input:(1)X={x_1,x_2,…,x_N},,x_iR~d,i=1,2,…,N,the dataset;(2)C,1C≤N,the number of clusters;(3)ε0,the stopping criterion;     

Journal of Zhejiang University-SCIENCE C (Computers & Electronics) Total contents

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A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.