校园网中双线服务器技术的应用探究

介绍了服务器双线接入技术的3种实现方案,并以笔者所在单位同时接入中国教育网(CERNET)和中国网通的双出口校园网模式为例,阐述了"单机单IP地址+智能DNS"的服务器双线接入方案的实施过程。     

无线局域网接入机制效率的分析研究

随着便携式计算机(包含笔记本和PDA)的快速普及,无线局域网IEEE 802.1 1成为目前短距离无线通讯技术的主流.无线局域网IEEE 802.11中采用DCF、PCF的接入机制,IEEE802.11e中采用EDCF、HCF的接入机制.对这四种接入机制的接入效率和服务质量 (QoS)进行分析,在此基础上提出了两种改进接入效率的方式,即碰撞导向工作模式与工作站数量导向工作模式.通过这两种方式使网络资源的分配更具有弹性,并满足具有不同优先级的工作站对效率的需求.     

ADSL高速接入技术的新发展

本文介绍了ADSL(Asymmetric Digital SubscriberLoop)接入技术的原理、技术优势,并分析了三种调制方式的特点及ADSL技术当前的新发展。     

ADSL高速接入技术的新发展

本介绍了ADSL(Asymmetric Digital Subscriber Loop)接入技术的原理、技术优势，并分析了三种调制方式的特点及ADSL技术当前的新发展。     

系统认识WLAN和PHS

无线局域网(WLAN)和小灵通(PHS)这两项无线接入方式在生活中逐渐应用普及.本文试从系统性能和当前应用情况两方面对无线局域网(WLAN)和小灵通(PHS)作出系统的比较说明,以期能对WLAN和PHS这两项无线接入技术有个较全面和清晰的说明.     

无线接入技术分析

首先介绍了无线接入的四种方式,在此基础上具体分析了宽带无线固定接入技术LMDS、宽带IP无线移动接入技术和基于蓝牙技术的两种无线接入技术,并给出了无线接入网的几种实现方案.     

WAP手机水表抄表系统应用研究

WAP(Wireless Application Protocol)是一种向移动终端提供互联网内容和先进增值服务的全球统一的开放式协议标准,是简化了的无线Internet协议。WAP将Internet和移动电话技术结合起来,使随时随地访问丰富的互联网络资源成为现实。WAP服务是一种手机直接上网,通过手机WAP"浏览器"浏览wap站点的服务,可享受新闻浏览、股票查询、邮件收发、在线游戏、聊天等多种应用服务。通过GPRS网络接入WAP,可充分发挥接入时延短(2秒接入)速率高、永远在线、切换方便等优点。     

ADSL宽带接入技术在校园网中的应用

一、ADSL宽带接入技术在校园网建设中的作用 非对称数字用户环路ADSL(Asymmetric Digital Subscriber Line)技术是美国贝尔通信研究所于1989年为推动视频点播(VoD)业务研发的数字用户线(xDSL)高速传输技术之一.所谓非对称是指在普通双绞铜线上利用数字信号处理及数字编码调制技术提供上下行数据速率不一致的高速传输.数据上行(用户到电信交换局)传输速率在256Kbps到1Mbps之间;下行(电信交换局到用户)传输速率在1.5Mbps到8Mbp之间.如果ADSL接入网配备了分离音频频带的分离器(Splitter),可提供下行方向1.5Mbps、上行方向512Kbps的传输速率,价格便宜,易于安装,更适合普通用户.因此特别适用于下行数据量很大的业务,如Internet接入,远端LAN接入和视频点播等.     

无线网络的接入技术

随着网络的发展，网络接入技术已经从有线接入发展到无线接入的阶段，目前，无线网络一共有三类：IEEE802．11系列接入技术，蓝牙无线接入技术及家庭射频（HomeRF)技术，在此，本文对这三种技术作一介绍并对无线网络接入作一具体实例说明。     

试析宽带无线接入较传统有线接入方式的优势

介绍宽带无线接入技术的性能特点、适用范围,与传统有线接入技术进行对比,阐述了宽带无线接入技术的发展趋势与发展格局.     

An application-layer based centralized information access control for VPN

INTRODUCTION AND BACKGROUND In the last decade, as the Internet becomes a popular low-cost backbone infrastructure, many or- ganizations and companies use it to establish their secure private network, which is known as VPN (Virtual Private Network) technology (Cohen, 2003). Generally, VPN implements confidentiality of data, message integrity and endpoint authentication by the security protocols (such as IPSec: IP Security (Kent and Atkinson, 1998) and TLS/SSL: Transport Lay…     

宽带接入技术探讨

接入网面临从窄带到宽带,从电路方式到分组方式转型,本文从接入路径和接入技术方 面,提出了对发展宽带接入网的一些认识和看法.     

NAS在电信网中的应用

网络接入服务器(NAS)位于公共电话网PSTN或综合业务数字网ISDN与Internet之间,为远程用户提供Internet接入能力,多链路捆绑、回呼等,并根据当前电信网现状,结合设备特点为电信运营商、ISP等提供了优选的设备组网方案.     

Advocates for Access: Do We Really Need a European Access Network?

The “European Access Network” is the only European‐wide non‐governmental body that focuses exclusively on widening participation in higher education, but in an age of “mass” higher education, who needs advocates for access? Surely the case for greater equity has already been made and won? A close look at the evidence, however, indicates that those who were under‐represented before are often under‐represented still. The European Access Network highlights this problem, demolishes the myths by examining the evidence, identifies solutions, promotes good practice, and puts on pressure for a more equitable higher education. This article investigates the progress that is being made, identifies what remains to be done, and suggests the most effective strategies for success.     

多域环境下的分布式RBAC模型

1Introduction Withthedevelopmentofdistributedsystems,access controlinmulti domainenvironmentsisrequiredinan increasingnumberofapplications.Manynewrequire mentshavebeenproposed[1,2].Withtheschemaofmultiplecomputersystemcoali tion,restrictedcooperationisnee…     

Using learning analytics to assess student engagement and academic outcomes in open access enabling programmes

Curriculum design, teaching methods, assessments and range of academic support need to be inclusive in Open Access Enabling courses. The findings of this study confirm a correlation between student access to online learning materials and a positive impact on grades in science courses. More specifically, students who frequently use the online learning system to access materials have better assessment and exam results.     

校园网安全策略体系的构建

随着校园网的建成和使用,如何保障网络正常运行,网络资源的合法访问,是网络免受黑客、病毒和其他不良意图的攻击显得尤为重要。因此,校园网安全状况应得到校园网的规划者、建设者和管理者的高度重视。必须制定相应网络安全策略,提出系统化的解决方案。本文简要介绍了校园网安全的威胁因素,根据网络访问机制,指出校园网安全问题的表现形式并就校园网安全给出了五种相应的管理策略。     

宽带通信接入网系统漫谈

对宽带通信接入网的基本业务情况进行了分析,并介绍了面向未来（IPTV等）三重业务播放（triple-play）通信功能的宽带接入网的技术方案。     

Using Activity Theory to explore the management of General Certificate of Education (GCSE) access arrangements

Access arrangements are the way in which awarding bodies for public examinations in England, such as the General Certificate of Secondary Education, make reasonable adjustments for students with special educational needs and disabilities. SENCos have expressed concerns about the onerous nature of managing requirements for access arrangements, both administratively and practically, but there has been little explanation of why an apparently straightforward process proves so challenging. In this study, the development of a whole-school system to improve the administrative and practical management of access arrangements is used to seek to understand how the requirements set (and re-set) annually interact with school systems and processes to render the administration of access arrangements potentially complex, time-consuming and unpredictable. Scotland's flexible, school-led framework of requirements for the management of public examination assessment arrangements is highlighted as potentially more fit-for-purpose for the organisation of statutory reasonable adjustments for educational assessment.