浅谈VoIP技术原理与发展应用

VoIP技术也就是因特网语音技术,它代表了因特网通信的发展潮流。本文首先从VoIP的工作原理出发,分析了它的优点及使用的技术和标准,其次阐述了VoIP在应用中遭遇的问题及未来应用的发展趋势。     

基于组件的多层数据库应用设计

因特网技术的快速发展扩展了多层计算模式的应用范围，由Web服务器、应用服务器和数据库服务器形成的多层数据库模型形成了目前因特网应用的骨干。使用CORBA技术构建多层分布式系统已经成为当前的主流技术，它大大降低了健壮的、大规模企业级系统的开发复杂度。     

技术新闻

日本NTT公司推动VolP移动电话应用 不久以后,日本宽带服务商NTT-ME公司的用户将可以通过一个无线移动终端(比如PDA)在自己公司的宽带网,住所的宽带网甚至公众热点间漫游,还能把这个终端当做应用IP协议的手机。 这是一种基于PDA的宽带无线IP电话应用。目前,很多厂商使用VolP技术将固定电话变成IP电话,而VolP移动电话其实就是这种IP电话的移动电话版。NTT-ME是日本电报电话公司NTT的子公司,是日本最大的宽带服务提供商,也是第一家提供VolP移动电话服务的无线LAN接入服务运营商。NTT-ME正在进行无线LAN接入服务“NeoMobile”试验,作为试验的一部分,在“NeoMobile”试验服务区域内,你可以使用具有VolP(语音IP)功能的PDA进行通话。     

富因特网应用程序使用与发展概览

富因特网应用程序是一种新型的因特网应用程序,它尝试填补本地应用程序和常规因特网应用程序之间的可用性差距。富因特网应用是Web发展的必然产物,也是Web应用发展的趋势和方向。本文是作者把富因特网应用技术的特性做了简单归纳。     

IntServ与DiffServ在VoIP QoS中的应用分析

介绍了VoIP QoS技术，针对当前两大主流QoS模型IntServ和DiffServ，论述了各自的工作原理及其在VoIP应用中的特点，并通过分析两种模型各自的优缺点，对一种结合两者优势的VolP的QoS模型方案作了探讨。     

网络电话，明天的电话？

VolP极有可能成为改变固定电话通讯方式最重要的技术,但它现在要面对的问题除了技术需要进一步完善外,还要打破电信业的那些传统势力     

一个基于因特网的个性化信息服务系统的设计和实现

该系统和搜索引擎相结合，以整个因特网为基础，向用户提供实时的， 自动推送式的个性化信息服务，本文详细介绍了该系统的原理、技术、逻辑结构，流程及实现方式，并通过一个实例说明了它的应用。     

VoIP的发展与现状探析

VolP(网络电话)自从被列为2005年电子商务的十大新走向之一后,许许多多公司都在不同程度上涉足了VolP领域。VolP正以全新的面貌出现在传统电信行业和世人面前,受到各国电信部门和厂商的重视。本文对VolP的相关知识进行论述并对VolP的市场前景和发展方向进行了预测和展望。     

简述AES高级加密标准

1 引言 随着因特网的发展,信息传输及存储的安全问题成为影响因特网应用发展的重要因素.信息安全技术也就成为了人们研究因特网应用的新热点.     

一种基于移动因特网的实时Email系统

移动因特网正日益成为通信领域的热点,WAP技术的应用逐渐使得移动终端用户可以随时随地地访问因特网。而传统的Email系统并不能适应这种实时性的要求。本文首先简要介绍移动因特网和传统Email技术,接着构造一个WAP的应用模型,最后描述它的实现并展望未来。     

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.     

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.     

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.     

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.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

正~~