传输网络

Large systems and computer networks typically use more sophisticated methods of transmission, such as synchronous or bisynchronous, because of the large overhead penalty of 20% in asynchronous transmission.

大型系统和计算机网络通常使用更为复杂的传输方法，例如同步或双同步。异步传输中存在超过20%的传输损失。

Networks are works transmitted in the form of digital signal, as well as by the carrier of internet,including digitized works, digital works and homepage works, the copyright of these three kinds of types respectiv ely belon gs to the people who owns the copyright of original works the author and interne t supervisor.

网络作品是以数字信号的形式和以网络为载体进行传播的作品，它包括数字化作品、数字式作品和主页作品三种类型。这三种类型作品的著作权分别归属于原作品的著作权人、创作的作者和网站管理者。网络作品在网上传输实质上是作者使用作品的方式之一，应由著作权人享有不同于传统复制权和发行权的"信息网络传播权"。

With the high-speed development of Internet, network link rate are increasing contiguously, while network applications and services are raising a diversity trend. Thus, the network equipments (routers, etc.) have to meet the increasing requirements of services and performance, including support for differentiated services, and flexible service extension capability, etc.

随着Internet网络的飞速发展，网络传输速率不断提高，网络应用和服务逐渐多样化，这对路由器等网络设备的服务和性能提出了更高的要求，包括对区分性服务的支持以及灵活的服务扩展能力等。

It with wired compares mainly has the cost to be low, carries conveniently, omits the wired wiring the worry; Specially is suitable to grasping the equipment the correspondence, the battery power supply equipment, the vehicles monitoring, the remote control, the telemetering, the small wireless network, wireless copies the table, the system, the plot messenger call, the industry data acquisition system, the wireless label, the status recognition, must contacts the RF smart card, the small wireless data terminal, the safe fire protection is systematic, wireless domain and so on in external guidance system, biological signal gathering, hydrometeorology monitoring, robot control, digital audio frequency, numeral image transmission the low power loss, the microminiaturization is the current wireless correspondence product then takes along the product in particular the urgent need and the key question.

它与有线相比主要有成本低，携带方便，省去有线布线的烦恼；特别适用于手持设备的通信、电池供电设备、车辆监控、遥控、遥测、小型无线网络、无线抄表、门禁系统、小区传呼、工业数据采集系统、无线标签、身份识别、非接触RF智能卡、小型无线数据终端、安全防火系统、无线遥控系统、生物信号采集、水文气象监控、机器人控制、数字音频、数字图像传输等领域中。低功耗、微型化是当前无线通信产品尤其是便携产品的迫切要求和关键问题。无线通信的另一个关键问题是数据传输的可靠性，这取决于诸多因素，如频率选择、同频干扰、传输距离、天线选择等，这些在设计无线通信系统时都要认真考虑和比较。

Describe the requirements of data transfer in wide-area grid environment and the characteristic of grid data transfer protocol-GridFTP,the parallel transfer mechanism in GridFTP is primarily analyzed.

分析论述了广域网格网络中数据传输的需求以及网格数据传输协议—GridFTP的性能特点，对GridFTP中最重要的并行传输机制进行了探讨。

Then the types of upper sensors are determined. The CMOS chip AT89C2051 is used in this system because there is only a small quantity of program to be stored. This system uses wireless transmission module D21DL to form the network of wireless transmission. In this way, such disadvantages as low removability and expansibility and longtime construction are avoided. Digital filtering method is applied to improve anti-jamming performance.

由于程序存储量较少，现场的CPU选用ATMEL公司的低档型芯片AT89C2051；为了避免采用有线数据传输导致的系统可移动性差、系统扩充性能差和系统布置线缆繁琐、施工周期长等缺点，本系统采用了无线数据传输模块D21DL构成系统无线网络传输；同时设计了包括电源电路、显示电路、存储电路和报警电路等构成系统的所有电路。

This new platform, considering the relationship among teaching, learning and managing, solving the conflict of resources share and intelligence prosperity, adopting latest theory on learning and mature technology, has more advantages than the existing platform. Firstly, it integrates the advantages of Internet and Satellite communication system and achieves the seamless connection. Secondly, it adopts the coding technology of streaming media with MEPG-4, which makes it possible that the on-line instruction, the schedular broadcast instruction and the distributed course ware on demand can be broadcast on the two networks. Thirdly, it considers the problems of security, user certification and the protection of intelligence property. Fourthly, it is possible to link education resources from all united university, and is able to share resources for lifelong learning individuals or group.

此次清华大学远程教育播出平台的改造，本着现有平台与未来需求相结合；最新的学习理论与成熟的信息技术相结合；资源传输与对学生的学习支持相结合；教育资源开放与知识产权保护相结合的设计理念，综合考虑了远程教育环境中教、学、管三方面的需求和关系，因而具有多方面的优势：新平台整合了互联网和卫星网各自的优势，在技术上实现了天网与地网的无缝连接；新平台对传输的教育节目采用 MPEG-4编码方式进行流媒体播出，在传输上实现了基于两种网络的实时课堂直播、录播和基于互联网的分布式课件点播的多种需求；新平台集资源加密、用户认证和授权等功能于一体，可有效地保护远程教育中的知识产权；新平台将各联盟学校的教育资源进行整合后重新提供给学习的个体或团体，较好地实现了资源共享。

It detailedly dissertates streaming media technology and it's system roof garden, and analyzes multimedia constringent technology, multimedia network transmit technology and multimedia databank technology.

着重论述了流媒体技术及其系统平台，分析了VOD系统的多媒体数据压缩技术、多媒体网络传输技术、多媒体数据库技术，并讨论了VOD系统中MPEG-4视频流的传输及其传输协议。

The main features of this paper is: nothing to do with the platform, this system can be compatible with the majority of software and hardware used by the platform, as well as various database platform, shielding the differences of hardware and software platform such as network, operating systems, databases, application systems and so on, so that enterprises and institutions could achieve seamless, transparent data exchange through data exchange system; Java technology used to develop the system transplantability; using data exchange center to achieve centralized data processing, different data format conversion, increased system scalability; from data transmission, authentication, access control, encryption and more news content log-class areas enhanced data exchange system security; using DES and RSA algorithm , increased the confidentiality of data transmission; create WrapperTimer category achieved data transmission timing implementation and reduce the dependence on artificial.

设计的系统与平台无关，能兼容企业所用的大多数软硬件平台，以及各种数据库平台，屏蔽网络、操作系统、数据库、应用系统等软硬平台的差异，使企事业单位通过数据交换系统实现无缝的、透明的交换数据；采用数据交换中心来实现数据的集中处理、不同数据格式的转换，增加了系统的可扩展性；从数据传输、身份认证、权限控制、消息内容加密和多级日志等多方面增强数据交换系统的安全性；用DES和RSA算法对XML文件或XML文件中的元素进行加密，增加传输数据的保密性；创建WrapperTimer类实现了数据传输的定时执行，降低了对人工的依赖性。

We conclude that the transmission ranges assignment of all coronas is the most effectively approach to prolong the network lifetime after nodes deployment.

将所有环的传输距离组成一组传输距离序列，网络中的节点基于传输距离序列路由传递数据。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了