智能家居中英文翻译

第一篇：智能家居中英文翻译

智能家居

智能家居是利用先进的计算机技术、网络通讯技术、综合布线技术、依照人体工程学原理，融合个性需求，将与家居生活有关的各个子系统如安防、灯光控制、窗帘控制、煤气阀控制、信息家电、场景联动、地板采暖等有机地结合在一起，通过网络化综合智能控制和管理，实现“以人为本”的全新家居生活体验。

基本介绍

智能家居是人们的一种居住环境，其以住宅为平台安装有智能家居系统，实现家庭生活更加安全，节能，智能，便利和舒适。以住宅为平台，利用综合布线技术、网络通信技术、智能家居-系统设计方案安全防范技术、自动控制技术、音视频技术将家居生活有关的设施集成，构建高效的住宅设施与家庭日程事务的管理系统，提升家居安全性、便利性、舒适性、艺术性，并实现环保节能的居住环境。

又称智能住宅，在国外常用Smart Home表示。与智能家居含义近似的有家庭自动化（Home Automation）、电子家庭（Electronic Home、E-home）、数字家园（Digital Family）、家庭网络（Home Net/Networks for Home）、网络家居（Network Home）、智能家庭/建筑（Intelligent Home/Building），在我国香港和台湾等地区，还有数码家庭、数码家居等称法。

主要特色

2.1 随意照明

控制随意照明控制，按几下按钮就能调节所有房间的照明，各种梦幻灯光，可以随心创造！智能照明系统具有软启功能，能使灯光渐亮渐暗； 灯光调光可实现调亮调暗功能,让你和家人分享温馨与浪漫,同时具有节能和环保的效果；全开全关功能可轻松实现灯和电器的一键全关和一键全开功能，并具有亮度记忆功能。

2.2 简单安装

智能家居系统可以实现简单地进行安装，而不必破坏隔墙，不必购买新的电气设备，系统完全可与你家中现有的电气设备，如灯具、电话和家电等进行连接。各种电器及其它智能子系统既可在家操控，也能完全满足远程控制。

2.3 可扩展性

智能家居系统是可以扩展的系统，最初，你的智能家居系统可以只与照明设备或目前常用的电器设备连接，将来也可以与其他设备连接，以适应新的智能生活需要。

既便您的家居已装修也可轻松升级为智能家居。无线控制的智能家居系统可以不破坏原有装修，只要在一些插座等处安装相应的模块即可实现智能控制，更不会对原来房屋墙面造成破坏。

主要功能

3.1 一 遥控控制

您可以使用遥控器来控制家中灯光，热水器，电动窗帘，饮水机，空调等设备的开启和关闭；通过这支遥控器的显示屏可以在一楼（或客厅）来查询并显示出二楼（或卧室）灯光电器的开启关闭状态；同时这支遥控器还可以控制家中的红外电器诸如：电视，DVD，音响等红外电器设备――万能遥控器。

3.2 二 电话远程控制

高加密（电话识别）多功能语音电话远程控制功能，当您出差或着在家外边办事，您可以通过手机，固定电话来控制家中的空调和窗帘，灯光电器，使之提前为客户制冷或制热或进行开启和关闭状态，通过手机或固定电话知道家中电路是否正常，各种家用电器（例如冰箱里的食物等），还可以得知室内的空气质量（屋内外可以安装类似烟雾报警器的电器）从而控制窗户和紫外线杀菌装置进行换气或杀菌，此外根据外部天气的优劣适当的加湿屋内空气和利用空调等设施对屋内进行升温。主人不在家时，也可以通过手机或固定电话来自动给花草浇水、宠物喂食等。控制卧室的柜橱对衣物、鞋子、被褥等杀菌、晾晒等。

3.3 三 定时控制

您可以提前设定某些产品的自动开启关闭时间，如：电热水器每天晚上 20:30 分自动开启加热，23:30 分自动断电关闭，保证您在享受热水洗浴的同时，也带来省电，舒适和时尚。当然电动窗帘的自动开启关闭时间更不在话下。3.4 四 集中控制

您可以在进门的玄关处就同时打开客厅，餐厅和厨房的灯光，厨宝等电器，尤其是在夜晚您可以在卧室控制客厅和卫生间的灯光电器，既方便又安全，还可以查询他们的工作状态。

3.5 五 场景控制

您轻轻触动一个按键，数种灯光，电器在您的“意念”中自动执行，使您感受和领略科技时尚生活的完美和简捷，高效

3.6 六 网络远程控制

在办公室，在出差的外地，只要是有网络的地方，您都可以通过 Internet 来登陆到您的家中，在网络世界中通过一个固定的智能家居控制界面来您家中的电器，提供一个免费动态域名。主要用于远程网络控制和电器工作状态信息查询，例如您出差在外地，利用外地网络计算机，登陆相关的IP地址，您就可以控制远在千里之外您自家的灯光，电器，在返回住宅上飞机之前，将您家中的空调或是热水器打开„

3.7 七 全球视频监控功能

在任何时间、任何地点直接透过局域网络或宽带网络，使用浏览器（如IE），进行远程影像监控，语音通话。另外还支持远程PC机、本地SD卡存储，移动侦测邮件传输、FTP传输，对于家庭用远程影音拍摄与拍照更可达成专业的安全防护与乐趣。

3.8 八 安防报警功能

当有警情发生时，能自动拨打点电话，并联动相关电器做报警处理

3.9 九 影音设备共享功能

家庭影音控制系统包括家庭影视交换中心（视频共享）和背景音乐系统（音频共享）。是家庭娱乐的多媒体平台，它运用先进的微电脑技术、无线遥控技术和红外遥控技术，在程序指令的精确控制下，把机顶盒、卫星接收机、DVD、电脑等多路信号源，能够根据用户的需要，发送到每一个房间的电视机、音响等终端设备上 , 实现一机共享客厅的多种视听设备。您的家庭就是一个独特设计的AV影视交换中心。

客厅的DVD影碟机、数字电视机顶盒、卫星电视接收机等任意4种视听设备共享到5个房间观看并可以遥控；（卧室房、卫生间、书房等房间任选其二加上客厅）为您家中的CD/TV/FM/MP3 音源（或数字电视机顶盒、卫星电视机顶盒、IPTV、网络在线电影、DVD等）音视频设备解决共享问题，为您解决音视频设备的异地遥控、换台、音量操作目的，如同您在卧室安装一个数字电视机顶盒（VCD、DVD）卫星电视机顶盒一样的效果，及其方便。

3.10 十 背景音乐系统

简单地说，就在任何一间房子里，包括客厅、卧室、厨房或卫生间，均可布上背景音乐线，通过 1 个或多个音源，(CD/TV/FM/MP3 音源)可以让每个房间都能听到美妙的背景音乐

配合AV影视交换产品，可以用最低的成本，不仅实现了每个房间音频和视频信号的共享，而且可以各房间独立的遥控选择背景音乐信号源，可以远程开机、关机、换台、快进、快退等，是音视频、背景音乐共享和远程控制的最佳的性价比设计方案！

3.11 十一 数字家庭娱乐系统

“数字娱乐”则是利用书房电脑作为家庭娱乐的播放中心，客厅或主卧大屏幕电视机上播放和显示的内容来源于互联网上海量的音乐资源、影视资源、电视资源、游戏资源、信息资源等等。安装“笑仙居数码娱乐终端”后，家庭的客厅、卧室、起居室等地方都可以获得视听娱乐内容。安装简单，用网络面板和一根超五类线连接设备。

3.12 十二 综合布线系统

是通过一个总管理箱将电话线、有线电视线、宽带网络线、音响线等被称为弱电的各种线统一规划在一个有序的状态下，以统一管理居室内的电话、传真、电脑、电视、影碟机、安防监控设备和其他的网络信息家电，使之功能更强大、使用更方便、维护更容易、更易扩展新用途.实现电话分机，局域网组建，有线电视共享等。

3.13 十三 指纹锁 您一定有过这样的尴尬：由于某种原因忘记带了家中的房门钥匙，或是家中亲人或客人造访，您恰恰不能立即赶回等等!如果这个时候能在单位或遥远的外地用手机或是电话将房门打开，该是多么方便呀！

并且在单位或遥远的外地用手机或是电话“查询”一下家中指数码指纹锁的“开，关”状态，是不是让您更会感到安全！世界顶尖生物识别，指纹技术与密码技术的完美结合，三项独立开门方式：指纹、密码和机械钥匙，安全方便

3.14 十四 新风空气调节

有一种设备既不用整日去开窗（有的卫生间是密闭的），就能定时为您更换经过过滤的新鲜空气哪（外面的空气经过过滤近来，同时将屋内的浊气排除）！

3.15 十五 宠物保姆

拨通家里的电话，就能给自己心爱的宠物喂食，还能听到它的声音，这该是一件多么富有情趣和时尚的生活！研制开发了具有高科技水平、操作简易的电话远程控制，自动定时控制，遥控控制的宠物喂食机„„

发展历程

1999年3月10日,微软公司董事长比尔·盖茨在深圳宣布了“维纳斯计划”。这是一项专门针对中国信息产业和家电市场,为中国量身定做的数字生活家电的解决方案。目标是要开发一个新的基于微软Windows CE操作系统的集计算、娱乐、教育、交流、通信和网上冲浪等功能于一体或相结合的产品。其产品最大的特点是价格便宜,易学易用,可满足非PC(个人电脑、微机)用户使用电脑和上网的需求。它是界于电脑和家电之间的产品。

两大部分

6.1 控制网络

如智能家居的基本结构图中右半部分所示，它主要是控制家庭中各种设备的运行状况，如电灯的灭/亮和亮度控制，空调的启/停以及温度和风量的控制，家庭安防系统的讯号采集和执行，各种开关量的输入，电动窗帘的开启/关闭控制，室内各种物理量的探测（如温度、湿度，各种气体含量等），四表（煤气表、电表、水表和暖气的热量表）数据的输出与指示等。

6.2 信息网络 在信息网络上传输的主要是音频和视频信号，它们的频率带宽一般要高达数兆赫兹，因此要求信息网络上的信息传输速率比较高，普遍应达到10 Mbps 以上。但相对说来，它的可靠性要求没有控制信息那么高。因为视音频信息在传输的前后都有一定的处理(如信号的压缩和编码/解压缩和解码)，这些处理都有一定的容错能力，而且即使有瞬时的错误，也只是影响瞬时的声音或图像的错误，而对设备以后的运行几乎没有影响。因此信息网络在技术上需要解决的主要问题是传输速率（即带宽），即在可能的条件下，尽可能提高信息网络的带宽。智能家居是通过统一的网络总线和控制平台将家庭的电器设备、灯光控制系统、安全控制系统、能源管理系统等连成一体的。目前智能家居的发展趋势是由集中控制到分布控制，与集中式控制相比，分布式控制不仅能减少布线，而且能提高系统的可靠性，当某一个节点出现故障时，只需将该节点从网络中拿走，而其它节点不受影响。

smart home

Smart home is the use of advanced computer technology, network communication technology, integrated wiring technology, in accordance with the principle of human body engineering, incorporating personality needs, will and household life on various subsystems, such as security, lighting control, curtain control, gas valve control, information appliances, linkage, floor heating, such as organically unifies in together, through network integrated intelligent control and management, implement “people-oriented” new household life experience.Basic introduction Smart home is one of the people living environment, the platform installation for housing is intelligent household system, realize the family life safer, energy efficient, intelligent, convenient and comfortable.To housing as a platform, the use of integrated wiring technology, network communication technology, smart home system design scheme of safety technology, automatic control technology, audio and video technology to integrate the household life related facilities, schedule to build efficient residential facilities and family affairs management system, improve home security, convenience, comfort, artistry, and realize environmental protection and energy saving living environment.Also called Smart Home, usually in Smart Home abroad.With Intelligent household meaning approximate Home Automation, Home Automation, Electronic Family(Electronic Home, E-Home), Digital Home, Digital Family), the Home Network(Home Net/Networks for Home), Network, Home Network(Home), Intelligent Home/Building(Intelligent Home/Building), Hong Kong and Taiwan and other regions in our country, and Digital Home, Digital Home, etc.Mr.Main features 2.1 lighting at will Control arbitrary lighting control, press a few buttons can adjust all the room lighting, lighting, all kinds of dream can create!Intelligent lighting system can have soft qi gong, can make the lights coming on gradually;Light dimmer can realize the dim light function, let you and your family to share warmth and romantic, at the same time, the effect of energy saving and environmental protection;Fully open barrier function can easily implement lights and appliances for a key barrier and a key open function, and has a brightness memory function.2.2 easy to install Smart home system can realize simply to install, without having to destroy the wall, don't have to buy a new electrical equipment, the system can be completely with your home's existing electrical equipment, such as lamps and lanterns, telephone and home appliances to connect.All kinds of electrical appliances and other intelligent subsystem can be control in the home, also can fully meet the remote control.2.3 extensibility Smart home system is the system can be extended, initially, your smart home system can only with lighting or the current commonly used electrical equipment connection, can connect to other devices in the future, in order to adapt to the new intelligent life need.Even when your home is decorated also can be easily upgraded to a smart home.Wireless control of smart home system can not destroy original decoration, as long as the corresponding module can be installed in the place such as some outlet to realize intelligent control, much less damage to the original building metope.The main function 3.1 a remote control You can use the remote control to control the lighting in the home, water heater, electric curtain, water dispensers, air conditioning equipment such as opening and closing;Through the display of the remote control can(or)sitting room on the first floor to query and show()or bedroom on the second floor lighting appliances open closed;At the same time, the remote control can control the infrared electric appliance in the home such as TV, DVD, audio and other infrared electric equipment, universal remote control.3.2 two telephone remote control High encryption(phone recognition)multi-function voice telephone remote control function, when you travel or work outside in the home, you can through mobile phones, fixed telephone to control home air conditioning and curtain, lighting appliances, make the cooling or heating for the customer in advance or open and closed, via mobile phone or fixed phone know home circuit is normal, all kinds of household electrical appliances(such as food in the refrigerator, etc.)can also be learned that indoor air quality(similar smoke detector can be installed outside the house appliances)to control the Windows and ultraviolet radiation sterilization device for ventilation or sterilization, moreover, according to the merits of the outside weather proper humidification indoor air and the use of air conditioning and other facilities of the room to heat up.Master is not at home, also can be automatically by cell phone or landline watering plants, feeding your pet, etc.Control of the bedroom cabinet to clothing, shoes, bedding, and other sterilization, drying, etc.3.3 three timing control You can set certain products automatically open shutoff time ahead of time, such as: electric water heater every night 20:30 points automatically open heating, power 30 points automatically shut down, to ensure you enjoy the hot water bath at the same time, also save electricity, comfortable and fashion.Electric curtains open automatically closing time is, of course, much more.3.4 four centralized control You can in the porch place that take the door open at the same time the sitting room, dining-room and kitchen lights, kitchen appliances such as treasure, especially at night you can control the lights of the sitting room and bathroom appliances in the bedroom, convenient and safe, can also track the status of their work.3.5 five scene control You gently touch a button, several kinds of lighting, electrical appliances automatically perform in your “mind”, make you feel and enjoy fashionable life perfect and simple science and technology, high efficiency 3.6 six network remote control In the office, on a business trip abroad, as long as there is a network of place, you can through the Internet to log in to your home, in the network world through a fixed of smart home control interface to your household electric appliances, provide a free dynamic DNS.Is mainly used for remote network control and electric work status information query, you are on a business trip in abroad, for example, using the nonlocal network computer, log in the IP address of the relevant, in far away you can control your own lighting, electrical appliances, before return home on a plane, will you home air conditioning or open the water heater...3.7 seven global video monitoring function At any time, any place directly through local area network or broadband network, using a browser(IE), remote video monitoring, voice calls.Also support remote PC, local SD card storage, motion detecting, mail transfer, FTP transmission for family use remote video and photo shooting more can achieve professional safety and pleasure.3.8 eight security alarm function When a case of, can automatically dial the telephone, and gang related appliances do alarm processing 3.9 9 av equipment sharing Home video control system including family film and television exchange center(video sharing)and background music system(audio sharing).Is family entertainment multimedia platform, it USES advanced microcomputer technology, wireless remote control technology and infrared remote control technology, under the precise control of program instruction, the set-top boxes, satellite receiver, DVD, computer, such as multi-channel signal source, can according to the needs of users, is sent to every room on terminal equipment such as TV, acoustics, realization of the sharing of the sitting room used a variety of audio and video equipment.Your family is a unique design of AV video exchange center.The DVD players of the sitting room, digital TV set-top boxes, satellite TV receiver and any kind of audio-visual equipment sharing 4 to 5 rooms to watch and can be remote control;(such as bedroom, study room, toilet room optional second plus a sitting room)for you in the home of CD/TV/FM/MP3 audio source(or digital TV set-top boxes, satellite TV set-top boxes, IPTV, online movies, DVD, etc.)share audio and video equipment to solve the problem, for you to solve different remote control, audio and video equipment in Taiwan, the volume operation purpose, as you install a digital TV set-top box in the bedroom(VCD, DVD)the same effect as satellite television set-top boxes, and convenient.31.0 background music system In simple terms, in any other houses, including the sitting room, bedroom, kitchen or bathroom, background music on the lines are, by one or more of the sound source,(CD/TV/FM/MP3 audio)can make a wonderful background music can be heard in every room Cooperate with AV video exchange of products, can use the lowest cost, not only realize the video and audio signals are Shared in every room, and can choose the background music of each room independent signal source, can remotely boot, shutdown, change channels, fast forward, fast return, such as audio and video, the background music sharing and the best ratio of design scheme of the remote control!3.11 11 digital home entertainment system “Digital entertainment” is a study of using computer as a home entertainment center, or sitting room advocate lie on a big screen TV broadcast and display the amount of content from the Internet in Shanghai music, film and television resources, TV, games, resources, information resources and so on.After installation “laughter xianju digital entertainment terminal”, the place such as sitting room, bedroom, living room, the family can get audio-visual entertainment content.Simple installation, use online panel and the super five kinds of thread connection equipment.3.12 twelve integrated wiring system Is through a total management cases will be attentive telephone line, cable, broadband networks, such as audio line is called the weak current line of unified planning in an orderly state, in a unified management inside the bedroom of telephone, fax, computer, TV, VCD, security monitoring equipment, and other network information home appliances, make the function more powerful, use more convenient, easier maintenance, are more likely to expand new USES.Realize the telephone extension, LAN construction, the sharing of the cable.3.13 13 fingerprint lock Embarrassing: you must have had for some reason forgot to bring the key to the door of home, or to visit relatives in the home or guest, you just can't immediately back to wait!If the time can in the unit or distant remotely by phone or the phone will open the door, how convenient it is！!And in the unit or distant remotely by phone or phone home “query,” refers to the digital fingerprint lock state of “open, close”, if let you feel more safe!The world's leading biometric fingerprint technology and password technology perfect combination of three independent way to open the door: fingerprint, password and mechanical keys, safe and convenient 3.14 the fourteenth air air conditioning Neither have a device to open the window all day(some toilet is closed), the timing for you to change the filtered fresh air which(outside air filtered recently, at the same time to the house of polluted air excluded).3.15 15 pet nanny Dial the telephone of home, you can give your beloved pet feeding, can hear its voice, this is a how fun and fashion life!Developed with high-tech level, operation simple telephone remote control, automatic timing control, remote control of pet feeding machine...The development course On March 10, 1999, Microsoft chairman Bill Gates announced the “Venus project” in shenzhen.This is a specifically for the Chinese information industry and home appliances market, tailor made for the Chinese digital life appliance solutions.Goal is to develop a new set of calculation based on the Microsoft Windows CE operating system, entertainment, education, communication, communication, and surfing the Internet, and other functions in one or a combination of products.The most obvious feature of the product is cheap, easy to learn and easy to use, can satisfy the PC(personal computer), computer user's demand to use the computer and the Internet.It is between computer and home appliance products.The two most 6.1 control network Such as intelligent household shown in the right part of the basic structure of the system, it is mainly to control all kinds of equipment running status in the family, such as the lights/the lights and light control, start/stop and the temperature of the air conditioning and air volume control, home security system of signal acquisition and execution, all kinds of switch quantity input, electric curtain open/close control, indoor detection of various physical quantities(such as temperature, humidity, all kinds of gas content, etc.), and four tables(gas meter, electricity meter, water meter, and the heat of the heat meter)the output of the data and instructions, etc.6.2 information network On the information network transmission is mainly audio and video signals, whose frequency bandwidth typically up to several GHZ, therefore requires information on the network information transmission rate is higher, generally should reach more than 10 megabits per second.But relatively speaking, the reliability requirement is not so high control information.Because audio information in the transport before and after a certain processing, such as signal compression and decoding and encoding/decompression), these processing has certain ability of fault tolerance, and even with the instantaneous error, is also affect the instantaneous sound or image of the error, and will have little impact on equipment running after.Therefore information network in technology transfer rate is the main problem that need to be solved(bandwidth), namely under the condition of possible, as far as possible to improve the information network bandwidth.Smart home is through unified network bus and the control platform to household electrical appliances, lighting control system, security control system becomes an organic whole repeatedly, energy management system, etc.The current development trend of the smart home is controlled by the centralized control to the distribution, compared with the centralized control and distributed control can not only reduce the wiring, and can improve the reliability of the system, when a certain node failure, just will take away from the network, the node and other nodes are not affected.

第二篇：中英文翻译

特种加工工艺

介绍

传统加工如车削、铣削和磨削等，是利用机械能将金属从工件上剪切掉，以加工成孔或去除余料。特种加工是指这样一组加工工艺，它们通过各种涉及机械能、热能、电能、化学能或及其组合形式的技术，而不使用传统加工所必需的尖锐刀具来去除工件表面的多余材料。

传统加工如车削、钻削、刨削、铣削和磨削，都难以加工特别硬的或脆性材料。采用传统方法加工这类材料就意味着对时间和能量要求有所增加，从而导致成本增加。在某些情况下，传统加工可能行不通。由于在加工过程中会产生残余应力，传统加工方法还会造成刀具磨损，损坏产品质量。基于以下各种特殊理由，特种加工工艺或称为先进制造工艺，可以应用于采用传统加工方法不可行，不令人满意或者不经济的场合：

1.对于传统加工难以夹紧的非常硬的脆性材料； 2.当工件柔性很大或很薄时； 3.当零件的形状过于复杂时；

4.要求加工出的零件没有毛刺或残余应力。

传统加工可以定义为利用机械（运动）能的加工方法，而特种加工利用其他形式的能量，主要有如下三种形式： 1.热能； 2.化学能； 3.电能。

为了满足额外的加工条件的要求，已经开发出了几类特种加工工艺。恰当地使用这些加工工艺可以获得很多优于传统加工工艺的好处。常见的特种加工工艺描述如下。

电火花加工

电火花加工是使用最为广泛的特种加工工艺之一。相比于利用不同刀具进行金属切削和磨削的常规加工，电火花加工更为吸引人之处在于它利用工件和电极间的一系列重复产生的（脉冲）离散电火花所产生的热电作用，从工件表面通过电腐蚀去除掉多余的材料。

传统加工工艺依靠硬质刀具或磨料去除较软的材料，而特种加工工艺如电火花加工，则是利用电火花或热能来电蚀除余料，以获得所需的零件形状。因此，材料的硬度不再是电火花加工中的关键因素。

电火花加工是利用存储在电容器组中的电能（一般为50V/10A量级）在工具电极（阴极）和工件电极（阳极）之间的微小间隙间进行放电来去除材料的。如图6.1所示，在EDM操作初始，在工具电极和工件电极间施以高电压。这个高电压可以在工具电极和工件电极窄缝间的绝缘电介质中产生电场。这就会使悬浮在电介质中的导电粒子聚集在电场最强处。当工具电极和工件电极之间的势能差足够大时，电介质被击穿，从而在电介质流体中会产生瞬时电火花，将少量材料从工件表面蚀除掉。每次电火花所蚀除掉的材料量通常在10-5～10-6mm3范围内。电极之间的间隙只有千分之几英寸，通过伺服机构驱动和控制工具电极的进给使该值保持常量。化学加工

化学加工是众所周知的特种加工工艺之一，它将工件浸入化学溶液通过腐蚀溶解作用将多余材料从工件上去除掉。该工艺是最古老的特种加工工艺，主要用于凹腔和轮廓加工，以及从具有高的比刚度的零件表面去除余料。化学加工广泛用于为多种工业应用（如微机电系统和半导体行业）制造微型零件。

化学加工将工件浸入到化学试剂或蚀刻剂中，位于工件选区的材料通过发生在金属溶蚀或化学溶解过程中的电化学微电池作用被去除掉。而被称为保护层的特殊涂层所保护下的区域中的材料则不会被去除。不过，这种受控的化学溶解过程同时也会蚀除掉所以暴露在表面的材料，尽管去除的渗透率只有0.0025～0.1 mm/min。该工艺采用如下几种形式：凹坑加工、轮廓加工和整体金属去除的化学铣，在薄板上进行蚀刻的化学造型，在微电子领域中利用光敏抗蚀剂完成蚀刻的光化学加工(PCM)，采用弱化学试剂进行抛光或去毛刺的电化学抛光，以及利用单一化学活性喷射的化学喷射加工等。如图6.2a所示的化学加工示意图，由于蚀刻剂沿垂直和水平方向开始蚀除材料，钻蚀（又称为淘蚀）量进一步加大，如图6.2b所示的保护体边缘下面的区域。在化学造型中最典型的公差范围可保持在材料厚度的±10%左右。为了提高生产率，在化学加工前，毛坯件材料应采用其他工艺方法（如机械加工）进行预成形加工。湿度和温度也会导致工件尺寸发生改变。通过改变蚀刻剂和控制工件加工环境，这种尺寸改变可以减小到最小。

电化学加工

电化学金属去除方法是一种最有用的特种加工方法。尽管利用电解作用作为金属加工手段是近代的事，但其基本原理是法拉第定律。利用阳极溶解，电化学加工可以去除具有导电性质工件的材料，而无须机械能和热能。这个加工过程一般用于在高强度材料上加工复杂形腔和形状，特别是在航空工业中如涡轮机叶片、喷气发动机零件和喷嘴，以及在汽车业（发动机铸件和齿轮）和医疗卫生业中。最近，还将电化学加工应用于电子工业的微加工中。

图6.3所示的是一个去除金属的电化学加工过程，其基本原理与电镀原理正好相反。在电化学加工过程中，从阳极（工件）上蚀除下的粒子移向阴极（加工工具）。金属的去除由一个合适形状的工具电极来完成，最终加工出来的零件具有给定的形状、尺寸和表面光洁度。在电化学加工过程中，工具电极的形状逐渐被转移或复制到工件上。型腔的形状正好是与工具相匹配的阴模的形状。为了获得电化学过程形状复制的高精度和高的材料去除率，需要采用高的电流密度（范围为10～100 A/cm2)和低电压（范围为8～30V）。通过将工具电极向去除工件表面材料的方向进给，加工间隙要维持在0.1 mm范围内，而进给率一般为0.1～20 mm/min左右。泵压后的电解液以高达5～50 m/s的速度通过间隙，将溶解后的材料、气体和热量带走。因此，当被蚀除的材料还没来得及附着到工具电极上时，就被电解液带走了。

作为一种非机械式金属去除加工方法，ECM可以以高切削量加工任何导电材料，而无须考虑材料的机械性能。特别是在电化学加工中，材料去除率与被加工件的硬度、韧性及其他特性无关。对于利用机械方法难于加工的材料，电化学加工可以保证将该材料加工出复杂形状的零件，这就不需要制造出硬度高于工件的刀具，而且也不会造成刀具磨损。由于工具和工件间没有接触，电化学加工是加工薄壁、易变形零件及表面容易破裂的脆性材料的首选。激光束加工

LASER是英文Light Amplification by Stimulated Emission of Radiation 各单词头一个字母所组成的缩写词。虽然激光在某些场合可用来作为放大器，但它的主要用途是光激射振荡器，或者是作为将电能转换为具有高度准直性光束的换能器。由激光发射出的光能具有不同于其他光源的特点：光谱纯度好、方向性好及具有高的聚焦功率密度。

激光加工就是利用激光和和靶材间的相互作用去除材料。简而言之，这些加工工艺包括激光打孔、激光切割、激光焊接、激光刻槽和激光刻划等。

激光加工（图6.4）可以实现局部的非接触加工，而且对加工件几乎没有作用力。这种加工工艺去除材料的量很小，可以说是“逐个原子”地去除材料。由于这个原因，激光切削所产生的切口非常窄。激光打孔深度可以控制到每个激光脉冲不超过一微米，且可以根据加工要求很灵活地留下非常浅的永久性标记。采用这种方法可以节省材料，这对于贵重材料或微加工中的精密结构而言非常重要。可以精确控制材料去除率使得激光加工成为微制造和微电子技术中非常重要的加工方法。厚度小于20 mm的板材的激光切割加工速度快、柔性好、质量高。另外，通过套孔加工还可有效实现大孔及复杂轮廓的加工。

激光加工中的热影响区相对较窄，其重铸层只有几微米。基于此，激光加工的变形可以不予考虑。激光加工适用于任何可以很好地吸收激光辐射的材料，而传统加工工艺必须针对不同硬度和耐磨性的材料选择合适的刀具。采用传统加工方法，非常难以加工硬脆材料如陶瓷等，而激光加工是解决此类问题的最好选择。

激光切割的边缘光滑且洁净，无须进一步处理。激光打孔可以加工用其他方法难以加工的高深径比的孔。激光加工可以加工出高质量的小盲孔、槽、表面微造型和表面印痕。激光技术正处于高速发展期，激光加工也如此。激光加工不会挂渣，没有毛边，可以精确控制几何精度。随着激光技术的快速发展，激光加工的质量正在稳步提高。

超声加工

超声加工为日益增长的对脆性材料如单晶体、玻璃、多晶陶瓷材料的加工需求及不断提高的工件复杂形状和轮廓加工提供了解决手段。这种加工过程不产生热量、无化学反应，加工出的零件在微结构、化学和物理特性方面都不发生变化，可以获得无应力加工表面。因此，超声加工被广泛应用于传统加工难以切削的硬脆材料。在超声加工中，实际切削由液体中的悬浮磨粒或者旋转的电镀金刚石工具来完成。超声加工的变型有静止（传统）超声加工和旋转超声加工。

传统的超声加工是利用作为小振幅振动的工具与工件之间不断循环的含有磨粒的浆料的磨蚀作用去除材料的。成形工具本身并不磨蚀工件，是受激振动的工具通过激励浆料液流中的磨料不断缓和而均匀地磨损工件，从而在工件表面留下与工具相对应的精确形状。音极工具振动的均匀性使超声加工只能完成小型零件的加工，特别是直径小于100 mm 的零件。

超声加工系统包括音极组件、超声发生器、磨料供给系统及操作人员的控制。音极是暴露在超声波振动中的一小块金属或工具，它将振动能传给某个元件，从而激励浆料中的磨粒。超声加工系统的示意图如图6.5所示。音极/工具组件由换能器、变幅杆和音极组成。换能器将电脉冲转换成垂直冲程，垂直冲程再传给变幅杆进行放大或压抑。调节后的冲程再传给音极/工具组件。此时，工具表面的振动幅值为20～50μm。工具的振幅通常与所使用的磨粒直径大致相等。

磨料供给系统将由水和磨粒组成的浆料送至切削区，磨粒通常为碳化硅或碳化硼。另外，除了提供磨粒进行切削外，浆料还可对音极进行冷却，并将切削区的磨粒和切屑带走。

Nontraditional Machining Processes Introduction

Traditional or conventional machining, such as turning, milling, and grinding etc., uses mechanical energy to shear metal against another substance to create holes or remove material.Nontraditional machining processes are defined as a group of processes that remove excess material by various techniques involving mechanical, thermal, electrical or chemical energy or combinations of these energies but do not use a sharp cutting tool as it is used in traditional manufacturing processes.Extremely hard and brittle materials are difficult to be machined by traditional machining processes.Using traditional methods to machine such materials means increased demand for time and energy and therefore increases in costs;in some cases traditional machining may not be feasible.Traditional machining also results in tool wear and loss of quality in the product owing to induced residual stresses during machining.Nontraditional machining processes, also called unconventional machining process or advanced manufacturing processes, are employed where traditional machining processes are not feasible, satisfactory or economical due to special reasons as outlined below: 1.Very hard fragile materials difficult to clamp for traditional machining;2.When the workpiece is too flexible or slender;3.When the shape of the part is too complex;4.Parts without producing burrs or inducing residual stresses.Traditional machining can be defined as a process using mechanical(motion)energy.Non-traditional machining utilizes other forms of energy;the three main forms of energy used in non-traditional machining processes are as follows: 1.Thermal energy;2.Chemical energy;3.Electrical energy.Several types of nontraditional machining processes have been developed to meet extra required machining conditions.When these processes are employed properly, they offer many advantages over traditional machining processes.The common nontraditional machining processes are described in the following section.Electrical Discharge Machining(EDM)

Electrical discharge machining(EDM)sometimes is colloquially referred to as spark machining, spark eroding, burning, die sinking or wire erosion.It is one of the most widely used non-traditional machining processes.The main attraction of EDM over traditional machining processes such as metal cutting using different tools and grinding is that this technique utilizes thermoelectric process to erode undesired materials from the workpiece by a series of rapidly recurring discrete electrical sparks between workpiece and electrode.The traditional machining processes rely on harder tool or abrasive material to remove softer material whereas nontraditional machining processes such as EDM uses electrical spark or thermal energy to erode unwanted material in order to create desired shapes.So, the hardness of the material is no longer a dominating factor for EDM process.EDM removes material by discharging an electrical current, normally stored in a capacitor bank, across a small gap between the tool(cathode)and the workpiece(anode)typically in the order of 50 volts/10amps.As shown in Fig.6.1, at the beginning of EDM operation, a high voltage is applied across the narrow gap between the electrode and the workpiece.This high voltage induces an electric field in the insulating dielectric that is present in narrow gap between electrode and workpiece.This causes conducting particles suspended in the dielectric to concentrate at the points of strongest electrical field.When the potential difference between the electrode and the workpiece is sufficiently high, the dielectric breaks down and a transient spark discharges through the dielectric fluid, removing small amount of material from the workpiece surface.The volume of the material removed per spark discharge is typically in the range of 10-5 to 10-6 mm3.The gap is only a few thousandths of an inch, which is maintained at a constant value by the servomechanism that actuates and controls the tool feed.Chemical Machining(CM)

Chemical machining(CM)is a well known non-traditional machining process in which metal is removed from a workpiece by immersing it into a chemical solution.The process is the oldest of the nontraditional processes and has been used to produce pockets and contours and to remove materials from parts having a high strength-to-weight ratio.Moreover, the chemical machining method is widely used to produce micro-components for various industrial applications such as microelectromechanical systems(MEMS)and semiconductor industries.In CM material is removed from selected areas of workpiece by immersing it in a chemical reagents or etchants, such as acids and alkaline solutions.Material is removed by microscopic electrochemical cell action which occurs in corrosion or chemical dissolution of a metal.Special coatings called maskants protect areas from which the metal is not to be removed.This controlled chemical dissolution will simultaneously etch all exposed surfaces even though the penetration rates of the material removed may be only 0.0025-0.1mm/min.The basic process takes many forms: chemical milling of pockets, contours, overall metal removal, chemical blanking for etching through thin sheets;photochemical machining(pcm)for etching by using of photosensitive resists in microelectronics;chemical or electrochemical polishing where weak chemical reagents are used(sometimes with remote electric assist)for polishing or deburring and chemical jet machining where a single chemically active jet is used.A schematic of chemical machining process is shown in Fig.6.2a.Because the etchant attacks the material in both vertical and horizontal directions, undercuts may develop(as shown by the areas under the edges of the maskant in Fig.6.2b).Typically, tolerances of ±10% of the material thickness can be maintained in chemical blanking.In order to improve the production rate, the bulk of the workpiece should be shaped by other processes(such as by machining)prior to chemical machining.Dimensional variations can occur because of size changes in workpiece due to humidity and temperature.This variation can be minimized by properly selecting etchants and controlling the environment in the part generation and the production area in the plant.Electrochemical Machining(ECM)

Electrochemical metal removal is one of the more useful nontraditional machining processes.Although the application of electrolytic machining as a metal-working tool is relatively new, the basic principles are based on Faraday laws.Thus, electrochemical machining can be used to remove electrically conductive workpiece material through anodic dissolution.No mechanical or thermal energy is involved.This process is generally used to machine complex cavities and shapes in high-strength materials, particularly in the aerospace industry for the mass production of turbine blades, jet-engine parts, and nozzles, as well as in the automotive(engines castings and gears)and medical industries.More recent applications of ECM include micromachining for the electronics industry.Electrochemical machining(ECM), shown in Fig.6.3, is a metal-removal process based on the principle of reverse electroplating.In this process, particles travel from the anodic material(workpiece)toward the cathodic material(machining tool).Metal removal is effected by a suitably shaped tool electrode, and the parts thus produced have the specified shape, dimensions, and surface finish.ECM forming is carried out so that the shape of the tool electrode is transferred onto, or duplicated in, the workpiece.The cavity produced is the female mating image of the tool shape.For high accuracy in shape duplication and high rates of metal removal, the process is operated at very high current densities of the order 10-100 A/cm2,at relative low voltage usually from 8 to 30 V, while maintaining a very narrow machining gap(of the order of 0.1 mm)by feeding the tool electrode with a feed rate from 0.1 to 20 mm/min.Dissolved material, gas, and heat are removed from the narrow machining gap by the flow of electrolyte pumped through the gap at a high velocity(5-50 m/s), so the current of electrolyte fluid carries away the deplated material before it has a chance to reach the machining tool.Being a non-mechanical metal removal process, ECM is capable of machining any electrically conductive material with high stock removal rates regardless of their mechanical properties.In particular, removal rate in ECM is independent of the hardness, toughness and other properties of the material being machined.The use of ECM is most warranted in the manufacturing of complex-shaped parts from materials that lend themselves poorly to machining by other, above all mechanical methods.There is no need to use a tool made of a harder material than the workpiece, and there is practically no tool wear.Since there is no contact between the tool and the work, ECM is the machining method of choice in the case of thin-walled, easily deformable components and also brittle materials likely to develop cracks in the surface layer.Laser Beam Machining(LBM)

LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.Although the laser is used as a light amplifier in some applications, its principal use is as an optical oscillator or transducer for converting electrical energy into a highly collimated beam of optical radiation.The light energy emitted by the laser has several characteristics which distinguish it from other light sources: spectral purity, directivity and high focused power density.Laser machining is the material removal process accomplished through laser and target material interactions.Generally speaking, these processes include laser drilling, laser cutting, laser welding, and laser grooving, marking or scribing.Laser machining(Fig.6.4)is localized, non-contact machining and is almost reacting-force free.This process can remove material in very small amount and is said to remove material “atom by atom”.For this reason, the kerf in laser cutting is usually very narrow , the depth of laser drilling can be controlled to less than one micron per laser pulse and shallow permanent marks can be made with great flexibility.In this way material can be saved, which may be important for precious materials or for delicate structures in micro-fabrications.The ability of accurate control of material removal makes laser machining an important process in micro-fabrication and micro-electronics.Also laser cutting of sheet material with thickness less than 20mm can be fast, flexible and of high quality, and large holes or any complex contours can be efficiently made through trepanning.Heat Affected Zone(HAZ)in laser machining is relatively narrow and the re-solidified layer is of micron dimensions.For this reason, the distortion in laser machining is negligible.LBM can be applied to any material that can properly absorb the laser irradiation.It is difficult to machine hard materials or brittle materials such as ceramics using traditional methods, laser is a good choice for solving such difficulties.Laser cutting edges can be made smooth and clean, no further treatment is necessary.High aspect ratio holes with diameters impossible for other methods can be drilled using lasers.Small blind holes, grooves, surface texturing and marking can be achieved with high quality using LBM.Laser technology is in rapid progressing, so do laser machining processes.Dross adhesion and edge burr can be avoided, geometry precision can be accurately controlled.The machining quality is in constant progress with the rapid progress in laser technology.Ultrasonic Machining(USM)

Ultrasonic machining offers a solution to the expanding need for machining brittle materials such as single crystals, glasses and polycrystalline ceramics, and for increasing complex operations to provide intricate shapes and workpiece profiles.This machining process is non-thermal, non-chemical, creates no change in the microstructure, chemical or physical properties of the workpiece and offers virtually stress-free machined surfaces.It is therefore used extensively in machining hard and brittle materials that are difficult to cut by other traditional methods.The actual cutting is performed either by abrasive particles suspended in a fluid, or by a rotating diamond-plate tool.These variants are known respectively as stationary(conventional)ultrasonic machining and rotary ultrasonic machining(RUM).Conventional ultrasonic machining(USM)accomplishes the removal of material by the abrading action of a grit-loaded slurry, circulating between the workpiece and a tool that is vibrated with small amplitude.The form tool itself does not abrade the workpiece;the vibrating tool excites the abrasive grains in the flushing fluid, causing them to gently and uniformly wear away the material, leaving a precise reverse from of the tool shape.The uniformity of the sonotrode-tool vibration limits the process to forming small shapes typically under 100 mm in diameter.The USM system includes the Sonotrode-tool assembly, the generator, the grit system and the operator controls.The sonotrode is a piece of metal or tool that is exposed to ultrasonic vibration, and then gives this vibratory energy in an element to excite the abrasive grains in the slurry.A schematic representation of the USM set-up is shown in Fig.6.5.The sonotrode-tool assembly consists of a transducer, a booster and a sonotrode.The transducer converts the electrical pulses into vertical stroke.This vertical stroke is transferred to the booster, which may amplify or suppress the stroke amount.The modified stroke is then relayed to the sonotrode-tool assembly.The amplitude along the face of the tool typically falls in a 20 to 50 μm range.The vibration amplitude is usually equal to the diameter of the abrasive grit used.The grit system supplies a slurry of water and abrasive grit, usually silicon or boron carbide, to the cutting area.In addition to providing abrasive particles to the cut, the slurry also cools the sonotrode and removes particles and debris from the cutting area.

第三篇：中英文翻译

蓄电池 battery 充电 converter 转换器 charger

开关电器 Switch electric 按钮开关 Button to switch 电源电器 Power electric 插头插座 Plug sockets

第四篇：中英文翻译

Fundamentals This chapter describes the fundamentals of today’s wireless communications.First a detailed description of the radio channel and its modeling are presented, followed by the introduction of the principle of OFDM multi-carrier transmission.In addition, a general overview of the spread spectrum technique, especially DS-CDMA, is given and examples of potential applications for OFDM and DS-CDMA are analyzed.This introduction is essential for a better understanding of the idea behind the combination of OFDM with the spread spectrum technique, which is briefly introduced in the last part of this chapter.1.1 Radio Channel Characteristics Understanding the characteristics of the communications medium is crucial for the appropriate selection of transmission system architecture, dimensioning of its components, and optimizing system parameters, especially since mobile radio channels are considered to be the most difficult channels, since they suffer from many imperfections like multipath fading, interference, Doppler shift, and shadowing.The choice of system components is totally different if, for instance, multipath propagation with long echoes dominates the radio propagation.Therefore, an accurate channel model describing the behavior of radio wave propagation in different environments such as mobile/fixed and indoor/outdoor is needed.This may allow one, through simulations, to estimate and validate the performance of a given transmission scheme in its several design phases.1.1.1 Understanding Radio Channels In mobile radio channels(see Figure 1-1), the transmitted signal suffers from different effects, which are characterized as follows: Multipath propagation occurs as a consequence of reflections, scattering, and diffraction of the transmitted electromagnetic wave at natural and man-made objects.Thus, at the receiver antenna, a multitude of waves arrives from many different directions with different delays, attenuations, and phases.The superposition of these waves results in amplitude and phase variations of the composite received signal.Doppler spread is caused by moving objects in the mobile radio channel.Changes in the phases and amplitudes of the arriving waves occur which lead to time-variant multipath propagation.Even small movements on the order of the wavelength may result in a totally different wave superposition.The varying signal strength due to time-variant multipath propagation is referred to as fast fading.Shadowing is caused by obstruction of the transmitted waves by, e.g., hills, buildings, walls, and trees, which results in more or less strong attenuation of the signal strength.Compared to fast fading, longer distances have to be covered to significantly change the shadowing constellation.The varying signal strength due to shadowing is called slow fading and can be described by a log-normal distribution [36].Path loss indicates how the mean signal power decays with distance between transmitter and receiver.In free space, the mean signal power decreases with the square of the distance between base station(BS)and terminal station(TS).In a mobile radio channel, where often no line of sight(LOS)path exists, signal power decreases with a power higher than two and is typically in the order of three to five.Variations of the received power due to shadowing and path loss can be efficiently counteracted by power control.In the following, the mobile radio channel is described with respect to its fast fading characteristic.1.1.2 Channel Modeling The mobile radio channel can be characterized by the time-variant channel impulse response h(τ , t)or by the time-variant channel transfer function H(f, t), which is the Fourier transform of h(τ , t).The channel impulse response represents the response of the channel at time t due to an impulse applied at time t − τ.The mobile radio channel is assumed to be a wide-sense stationary random process, i.e., the channel has a fading statistic that remains constant over short periods of time or small spatial distances.In environments with multipath propagation, the channel impulse response is composed of a large number of scattered impulses received over Np different paths，Where

and ap, fD,p, ϕp, and τp are the amplitude, the Doppler frequency, the phase, and the propagation delay, respectively, associated with path p, p = 0,..., Np − 1.The assigned channel transfer function is

The delays are measured relative to the first detectable path at the receiver.The Doppler Frequency

depends on the velocity v of the terminal station, the speed of light c, the carrier frequency fc, and the angle of incidence αp of a wave assigned to path p.A channel impulse response with corresponding channel transfer function is illustrated in Figure 1-2.The delay power density spectrum ρ(τ)that characterizes the frequency selectivity of the mobile radio channel gives the average power of the channel output as a function of the delay τ.The mean delay τ , the root mean square(RMS)delay spread τRMS and the maximum delay τmax are characteristic parameters of the delay power density spectrum.The mean delay is

Where

Figure 1-2 Time-variant channel impulse response and channel transfer function with frequency-selective fading is the power of path p.The RMS delay spread is defined as Similarly, the Doppler power density spectrum S(fD)can be defined that characterizes the time variance of the mobile radio channel and gives the average power of the channel output as a function of the Doppler frequency fD.The frequency dispersive properties of multipath channels are most commonly quantified by the maximum occurring Doppler frequency fDmax and the Doppler spread fDspread.The Doppler spread is the bandwidth of the Doppler power density spectrum and can take on values up to two times |fDmax|, i.e.，1.1.3Channel Fade Statistics The statistics of the fading process characterize the channel and are of importance for channel model parameter specifications.A simple and often used approach is obtained from the assumption that there is a large number of scatterers in the channel that contribute to the signal at the receiver side.The application of the central limit theorem leads to a complex-valued Gaussian process for the channel impulse response.In the absence of line of sight(LOS)or a dominant component, the process is zero-mean.The magnitude of the corresponding channel transfer function

is a random variable, for brevity denoted by a, with a Rayleigh distribution given by

Where

is the average power.The phase is uniformly distributed in the interval [0, 2π].In the case that the multipath channel contains a LOS or dominant component in addition to the randomly moving scatterers, the channel impulse response can no longer be modeled as zero-mean.Under the assumption of a complex-valued Gaussian process for the channel impulse response, the magnitude a of the channel transfer function has a Rice distribution given by

The Rice factor KRice is determined by the ratio of the power of the dominant path to thepower of the scattered paths.I0 is the zero-order modified Bessel function of first kind.The phase is uniformly distributed in the interval [0, 2π].1.1.4Inter-Symbol(ISI)and Inter-Channel Interference(ICI)The delay spread can cause inter-symbol interference(ISI)when adjacent data symbols overlap and interfere with each other due to different delays on different propagation paths.The number of interfering symbols in a single-carrier modulated system is given by

For high data rate applications with very short symbol duration Td < τmax, the effect of ISI and, with that, the receiver complexity can increase significantly.The effect of ISI can be counteracted by different measures such as time or frequency domain equalization.In spread spectrum systems, rake receivers with several arms are used to reduce the effect of ISI by exploiting the multipath diversity such that individual arms are adapted to different propagation paths.If the duration of the transmitted symbol is significantly larger than the maximum delay Td τmax, the channel produces a negligible amount of ISI.This effect is exploited with multi-carrier transmission where the duration per transmitted symbol increases with the number of sub-carriers Nc and, hence, the amount of ISI decreases.The number of interfering symbols in a multi-carrier modulated system is given by

Residual ISI can be eliminated by the use of a guard interval(see Section 1.2).The maximum Doppler spread in mobile radio applications using single-carrier modulation is typically much less than the distance between adjacent channels, such that the effect of interference on adjacent channels due to Doppler spread is not a problem for single-carrier modulated systems.For multi-carrier modulated systems, the sub-channel spacing Fs can become quite small, such that Doppler effects can cause significant ICI.As long as all sub-carriers are affected by a common Doppler shift fD, this Doppler shift can be compensated for in the receiver and ICI can be avoided.However, if Doppler spread in the order of several percent of the sub-carrier spacing occurs, ICI may degrade the system performance significantly.To avoid performance degradations due to ICI or more complex receivers with ICI equalization, the sub-carrier spacing Fs should be chosen as

such that the effects due to Doppler spread can be neglected(see Chapter 4).This approach corresponds with the philosophy of OFDM described in Section 1.2 and is followed in current OFDM-based wireless standards.Nevertheless, if a multi-carrier system design is chosen such that the Doppler spread is in the order of the sub-carrier spacing or higher, a rake receiver in the frequency domain can be used [22].With the frequency domain rake receiver each branch of the rake resolves a different Doppler frequency.1.1.5Examples of Discrete Multipath Channel Models Various discrete multipath channel models for indoor and outdoor cellular systems with different cell sizes have been specified.These channel models define the statistics of the 5 discrete propagation paths.An overview of widely used discrete multipath channel models is given in the following.COST 207 [8]: The COST 207 channel models specify four outdoor macro cell propagation scenarios by continuous, exponentially decreasing delay power density spectra.Implementations of these power density spectra by discrete taps are given by using up to 12 taps.Examples for settings with 6 taps are listed in Table 1-1.In this table for several propagation environments the corresponding path delay and power profiles are given.Hilly terrain causes the longest echoes.The classical Doppler spectrum with uniformly distributed angles of arrival of the paths can be used for all taps for simplicity.Optionally, different Doppler spectra are defined for the individual taps in [8].The COST 207 channel models are based on channel measurements with a bandwidth of 8–10 MHz in the 900-MHz band used for 2G systems such as GSM.COST 231 [9] and COST 259 [10]: These COST actions which are the continuation of COST 207 extend the channel characterization to DCS 1800, DECT, HIPERLAN and UMTS channels, taking into account macro, micro, and pico cell scenarios.Channel models with spatial resolution have been defined in COST 259.The spatial component is introduced by the definition of several clusters with local scatterers, which are located in a circle around the base station.Three types of channel models are defined.The macro cell type has cell sizes from 500 m up to 5000 m and a carrier frequency of 900 MHz or 1.8 GHz.The micro cell type is defined for cell sizes of about 300 m and a carrier frequency of 1.2 GHz or 5 GHz.The pico cell type represents an indoor channel model with cell sizes smaller than 100 m in industrial buildings and in the order of 10 m in an office.The carrier frequency is 2.5 GHz or 24 GHz.COST 273: The COST 273 action additionally takes multi-antenna channel models into account, which are not covered by the previous COST actions.CODIT [7]: These channel models define typical outdoor and indoor propagation scenarios for macro, micro, and pico cells.The fading characteristics of the various propagation environments are specified by the parameters of the Nakagami-m distribution.Every environment is defined in terms of a number of scatterers which can take on values up to 20.Some channel models consider also the angular distribution of the scatterers.They have been developed for the investigation of 3G system proposals.Macro cell channel type models have been developed for carrier frequencies around 900 MHz with 7 MHz bandwidth.The micro and pico cell channel type models have been developed for carrier frequencies between 1.8 GHz and 2 GHz.The bandwidths of the measurements are in the range of 10–100 MHz for macro cells and around 100 MHz for pico cells.JTC [28]: The JTC channel models define indoor and outdoor scenarios by specifying 3 to 10 discrete taps per scenario.The channel models are designed to be applicable for wideband digital mobile radio systems anticipated as candidates for the PCS(Personal Communications Systems)common air interface at carrier frequencies of about 2 GHz.UMTS/UTRA [18][44]: Test propagation scenarios have been defined for UMTS and UTRA system proposals which are developed for frequencies around 2 GHz.The modeling of the multipath propagation corresponds to that used by the COST 207 channel models.HIPERLAN/2 [33]: Five typical indoor propagation scenarios for wireless LANs in the 5 GHz frequency band have been defined.Each scenario is described by 18discrete taps of the delay power density spectrum.The time variance of the channel(Doppler spread)is modeled by a classical Jake’s spectrum with a maximum terminal speed of 3 m/h.Further channel models exist which are, for instance, given in [16].1.1.6Multi-Carrier Channel Modeling Multi-carrier systems can either be simulated in the time domain or, more computationally efficient, in the frequency domain.Preconditions for the frequency domain implementation are the absence of ISI and ICI, the frequency nonselective fading per sub-carrier, and the time-invariance during one OFDM symbol.A proper system design approximately fulfills these preconditions.The discrete channel transfer function adapted to multi-carrier signals results in

where the continuous channel transfer function H(f, t)is sampled in time at OFDM symbol rate s and in frequency at sub-carrier spacing Fs.The duration

s is the total OFDM symbol duration including the guard interval.Finally, a symbol transmitted onsub-channel n of the OFDM symbol i is multiplied by the resulting fading amplitude an,i and rotated by a random phase ϕn,i.The advantage of the frequency domain channel model is that the IFFT and FFT operation for OFDM and inverse OFDM can be avoided and the fading operation results in one complex-valued multiplication per sub-carrier.The discrete multipath channel models introduced in Section 1.1.5 can directly be applied to(1.16).A further simplification of the channel modeling for multi-carrier systems is given by using the so-called uncorrelated fading channel models.1.1.6.1Uncorrelated Fading Channel Models for Multi-Carrier Systems These channel models are based on the assumption that the fading on adjacent data symbols after inverse OFDM and de-interleaving can be considered as uncorrelated [29].This assumption holds when, e.g., a frequency and time interleaver with sufficient interleaving depth is applied.The fading amplitude an,i is chosen from a distribution p(a)according to the considered cell type and the random phase ϕn,I is uniformly distributed in the interval [0,2π].The resulting complex-valued channel fading coefficient is thus generated independently for each sub-carrier and OFDM symbol.For a propagation scenario in a macro cell without LOS, the fading amplitude an,i is generated by a Rayleigh distribution and the channel model is referred to as an uncorrelated Rayleigh fading channel.For smaller cells where often a dominant propagation component occurs, the fading amplitude is chosen from a Rice distribution.The advantages of the uncorrelated fading channel models for multi-carrier systems are their simple implementation in the frequency domain and the simple reproducibility of the simulation results.1.1.7Diversity The coherence bandwidth of a mobile radio channel is the bandwidth over which the signal propagation characteristics are correlated and it can be approximated by

The channel is frequency-selective if the signal bandwidth B is larger than the coherence bandwidth.On the other hand, if B is smaller than , the channel is frequency nonselective or flat.The coherence bandwidth of the channel is of importance for evaluating the performance of spreading and frequency interleaving techniques that try to exploit the inherent frequency diversity Df of the mobile radio channel.In the case of multi-carrier transmission, frequency diversity is exploited if the separation of sub-carriers transmitting the same information exceeds the coherence bandwidth.The maximum achievable frequency diversity Df is given by the ratio between the signal bandwidth B and the coherence bandwidth，The coherence time of the channel is the duration over which the channel characteristics can be considered as time-invariant and can be approximated by

If the duration of the transmitted symbol is larger than the coherence time, the channel is time-selective.On the other hand, if the symbol duration is smaller than , the channel is time nonselective during one symbol duration.The coherence time of the channel is of importance for evaluating the performance of coding and interleaving techniques that try to exploit the inherent time diversity DO of the mobile radio channel.Time diversity can be exploited if the separation between time slots carrying the same information exceeds the coherence time.A number of Ns successive time slots create a time frame of duration Tfr.The maximum time diversity Dt achievable in one time frame is given by the ratio between the duration of a time frame and the coherence time, A system exploiting frequency and time diversity can achieve the overall diversity

The system design should allow one to optimally exploit the available diversity DO.For instance, in systems with multi-carrier transmission the same information should be transmitted on different sub-carriers and in different time slots, achieving uncorrelated faded replicas of the information in both dimensions.Uncoded multi-carrier systems with flat fading per sub-channel and time-invariance during one symbol cannot exploit diversity and have a poor performance in time and frequency selective fading channels.Additional methods have to be applied to exploit diversity.One approach is the use of data spreading where each data symbol is spread by a spreading code of length L.This, in combination with interleaving, can achieve performance results which are given for

by the closed-form solution for the BER for diversity reception in Rayleigh fading channels according to [40]

Whererepresents the combinatory function，and σ2 is the variance of the noise.As soon as the interleaving is not perfect or the diversity offered by the channel is smaller than the spreading code length L, or MCCDMA with multiple access interference is applied,(1.22)is a lower bound.For L = 1, the performance of an OFDM system without forward error correction(FEC)is obtained, 9

which cannot exploit any diversity.The BER according to(1.22)of an OFDM(OFDMA, MC-TDMA)system and a multi-carrier spread spectrum(MC-SS)system with different spreading code lengths L is shown in Figure 1-3.No other diversity techniques are applied.QPSK modulation is used for symbol mapping.The mobile radio channel is modeled as uncorrelated Rayleigh fading channel(see Section 1.1.6).As these curves show, for large values of L, the performance of MC-SS systems approaches that of an AWGN channel.Another form of achieving diversity in OFDM systems is channel coding by FEC, where the information of each data bit is spread over several code bits.Additional to the diversity gain in fading channels, a coding gain can be obtained due to the selection of appropriate coding and decoding algorithms.中文翻译 1基本原理

这章描述今日的基本面的无线通信。第一一个的详细说明无线电频道，它的模型被介绍，跟随附近的的介绍的原则的参考正交频分复用多载波传输。此外，一个一般概观的扩频技术，尤其ds-cdma，被给，潜力的例子申请参考正交频分复用，DS对1。分配的通道传输功能是

有关的延误测量相对于第一个在接收器检测到的路径。多普勒频率

取决于终端站，光速c，载波频率fc的速度和发病路径分配给速度v波αp角度页具有相应通道传输信道冲激响应函数图1-2所示。

延迟功率密度谱ρ（τ）为特征的频率选择性移动无线电频道给出了作为通道的输出功能延迟τ平均功率。平均延迟τ，均方根（RMS）的时延扩展τRMS和最大延迟τmax都是延迟功率密度谱特征参数。平均时延特性参数为

有

图1-2时变信道冲激响应和通道传递函数频率选择性衰落是权力页的路径均方根时延扩展的定义为 同样，多普勒频谱的功率密度（FD）的特点可以定义

在移动时变无线信道，并给出了作为一种金融衍生工具功能的多普勒频率通道输出的平均功率。多径信道频率分散性能是最常见的量化发生的多普勒频率和多普勒fDmax蔓延fDspread最大。多普勒扩散是功率密度的多普勒频谱带宽，可价值观需要两年时间| fDmax|，即

1.1.3频道淡出统计

在衰落过程中的统计特征和重要的渠道是信道模型参数规格。一个简单而经常使用的方法是从假设有一个通道中的散射，有助于在大量接收端的信号。该中心极限定理的应用导致了复杂的值的高斯信道冲激响应过程。在对视线（LOS）或线的主要组成部分的情况下，这个过程是零的意思。相应的通道传递函数幅度

是一个随机变量，通过给定一个简短表示由瑞利分布，有

是的平均功率。相均匀分布在区间[0，2π]。

在案件的多通道包含洛杉矶的或主要组件除了随机移动散射，通道脉冲响应可以不再被建模为均值为零。根据信道脉冲响应的假设一个复杂的值高斯过程，其大小通道的传递函数A的水稻分布给出

赖斯因素KRice是由占主导地位的路径权力的威力比分散的路径。I0是零阶贝塞尔函数的第一阶段是一致kind.The在区间[0，2π]分发。

1.1.4符号间（ISI）和通道间干扰（ICI）

延迟的蔓延引起的符号间干扰（ISI）当相邻的数据符号上的重叠与互相不同的传播路径，由于不同的延迟干涉。符号的干扰在单载波调制系统的号码是给予

对于高数据符号持续时间很短运输署<蟿MAX时，ISI的影响，这样一来，速率应用，接收机的复杂性大大增加。对干扰影响，可以抵消，如时间或频域均衡不同的措施。在扩频系统，与几个臂Rake接收机用于减少通过利用多径分集等，个别武器适应不同的传播路径的干扰影响。

如果发送符号的持续时间明显高于大的最大延迟运输署蟿最大，渠道产生ISI的微不足道。这种效果是利用多载波传输的地方，每发送符号的增加与子载波数控数目，因此，ISI的金额减少的持续时间。符号的干扰多载波调制系统的号码是给予

可以消除符号间干扰由一个保护间隔（见1.2节）的使用。

最大多普勒在移动无线应用传播使用单载波调制通常比相邻通道，这样，干扰对由于多普勒传播相邻通道的作用不是一个单载波调制系统的问题距离。对于多载波调制系统，子通道间距FS可以变得非常小，这样可以造成严重的多普勒效应ICI的。只要所有子载波只要是一个共同的多普勒频移金融衍生工具的影响，这可以补偿多普勒频移在接收器和ICI是可以避免的。但是，如果在对多普勒子载波间隔为几个百分点的蔓延情况，卜内门可能会降低系统的性能显着。为了避免性能降级或因与ICI卜内门更复杂的接收机均衡，子载波间隔财政司司长应定为

这样说，由于多普勒效应可以忽略不扩散（见第4章）。这种方法对应于OFDM的1.2节中所述，是目前基于OFDM的无线标准遵循的理念。

不过，如果多载波系统的设计选择了这样的多普勒展宽在子载波间隔或更高，秩序是在频率RAKE接收机域名可以使用[22]。随着频域RAKE接收机每个支部耙解决了不同的多普勒频率。

1.1.5多径信道模型的离散的例子

各类离散多与不同的细胞大小的室内和室外蜂窝系统的信道模型已经被指定。这些通道模型定义的离散传播路径的统计信息。一种广泛使用的离散多径信道模型概述于下。造价207[8]：成本207信道模型指定连续四个室外宏蜂窝传播方案，指数下降延迟功率密度谱。这些频道功率密度的离散谱的实现都是通过使用多达12个频道。与6频道设置的示例列于表1-1。在这种传播环境的几个表中的相应路径延迟和电源配置给出。丘陵地形导致最长相呼应。

经典的多普勒频谱与均匀分布的到达角路径可以用于简化所有的频道。或者，不同的多普勒谱定义在[8]个人频道。207信道的成本模型是基于一个8-10兆赫的2G，如GSM系统中使用的900兆赫频段信道带宽的测量。造价231[9]和造价259[10]：这些费用是行动的延续成本207扩展通道特性到DCS1800的DECT，HIPERLAN和UMTS的渠道，同时考虑到宏观，微观和微微小区的情况为例。空间分辨率与已定义的通道模型在造价259。空间部分是介绍了与当地散射，这是在基站周围设几组圆的定义。三种类型的通道模型定义。宏细胞类型具有高达500〜5000米，载波频率为900兆赫或1.8 GHz的单元尺寸。微细胞类型被定义为细胞体积约300米，1.2 GHz或5 GHz载波频率。细胞类型代表的Pico与细胞体积小于100工业建筑物和办公室中的10 m阶米室内信道模型。载波频率为2.5 GHz或24千兆赫。造价273：成本273行动另外考虑到多天线信道模型，这是不是由先前的费用的行为包括在内。

CODIT [7]：这些通道模型定义的宏，微，微微蜂窝和室外和室内传播的典型案例。各种传播环境的衰落特性是指定的在NakagamiSS）的不同扩频码L是长度，如图1-3所示的系统。没有其他的分集技术被应用。QPSK调制用于符号映射。移动无线信道建模为不相关瑞利衰落信道（见1.1.6）。由于这些曲线显示，办法，AWGN信道的一对L时，对MC-SS系统性能有很大价值。

另一种实现形式的OFDM系统的多样性是由前向纠错信道编码，在这里，每个数据位的信息分散在几个代码位。附加在衰落信道分集增益，编码增益一个可因适当的编码和解码算法的选择。

第五篇：中英文翻译标语

No trespassing!Violators will be shot;survivors will be shot again.严禁擅闯！违者将被射杀；幸存者将被再次射杀。

Those who throw objects at crocodiles will be asked to retrive them.向鳄鱼丢东西的人将被要求把东西取回。

Approaching end of the motorway.即将驶出高速。

“报案中心”Police Report Centre of X X City

“您先请”则翻译成“After you”

Staffonly 闲人勿进。

No littering 请勿乱投垃圾。

Keep right靠右驾驶。

Mind your head 小心碰头！

Disabled Only 残疾人专用。

Temporarily Closed 暂停服务。

Danger!High Voltage 止步！高压危险！

Keep off the Grass.请勿践踏草坪。

Please use handrail 请您扶好站好。

No Flash Photography 请勿使用闪光灯。

Fire escape, keep clear.安全出口，保持畅通。

Caution!Slippery When Wet 道路湿滑请小心！

Watch Your Step/ Mind the Step 下台阶请你小心。

All cycles will be removed 此处禁放自行车，违者拖走车辆。

Take Care of Your Belongings 请保管好您随身携带的物品。

Fragile!Handle with Care 易碎品，请轻拿轻放。

Visitors Please Register At Office 来宾请到办公室登记。

Children under 1 meter must be accompanied by an adult 1米以下的儿童须有成年人的陪同。Private parking.Vehicles left at owner's risk 私人停车处，违者后果自负。

Please close this gate securely on entry and exit 出入时请安全关闭此门。

Cycles are left at the owner's risk.National Maritime Museum accept no responsibility for damage or theft 请勿停放自行车，否则后果自负。国家海洋博物馆不为损坏或丢失负责。

※注意身体：（错误）notice your bodybody 有‘遗体’之意

(正确)pay attention to your health

※我一点也不放松自己（丝毫不敢怠慢的意思）

（错误）I daren't loose myself(我不敢松开某样东西)

(正确)I daren't relax my efforts.就业问题（错误）employment problem(正确)unemployment

新学期已过了一个月了（错误）Our new term has passed one month.(正确)One month has passed since the new term began.错welcome to our bus(again)

对thank you for riding with us

we are would be pleased to have you back in the future.错welcome to visit my blog

对I welcome you to my blog

缩略形式 welcome to my blog（to 是介词）

错误翻译--Scattering(散播)--紧急出口

deformed man toilet（丑陋人洗手间）--残疾人洗手间

green hand--生手，没有经验

Jack is a green hand at doing this work.1.Let's go and eat.Let's go and eat our meals.(CE-Chinese Englis)

2.We were quite disappointed that he said only a few words.He only said a few sentences.He made us very disappointed.(CE)

3.He went out for a walk after supper.After supper he went out for a walk.(CE)

英语族人两种说法都有，但中国人更趋向于后者。

4.It is Sunday today.Today is Sunday.(CE)

5.We found it impossible to get the result.We found that to get the result was impossible.(CE)

6.I was told.Some people told me.(CE)

7.He met with another Waterloo in his ambition.He got another defeat inhis ambition.(CE)

这涉及文化背景的差异。