科技英文翻译
科技英语的翻译技巧
摘要：本文主要阐述了科技英语的翻译技巧以及应遵循的准则关键词：科技英语；被动语态；名词化结构我们科技工作者在工作中经常需要了解国际国内交通发展的状况，借鉴国内外先进的科学技术或进行学术交流，这样不可避免地要翻阅大量的外文书刊和杂志。
虽然我们在学习普通英语的基础上掌握了几千个单词的词汇量，但对科技英文书刊的查阅仍有较大的困难。
科技英语（English for science and Technology，通常略为EST ），它之所以能同普通英语分道扬镳，形成一门独立的学科，很重要的原因在于它有不同于普通英语的特点，笔者根据自己多年的翻译经验，认为我们要掌握其中的几种技巧。
一、首先要拥有一本好的科技词典学习普通英语几年以后，你大约掌握几千个单词的词汇量，这时你就会发现英语拥有极其丰富多彩的词汇，但在科技文章中，又会对大量的专业词汇和术语而头疼。
有些词晦涩难懂，大而长，看起来吓人，如posttention（后张拉力），prefabricate（预制），意义比较简单，只要查一下词典就行。
有些词在文章中起着举足轻重的作用。
光凭上下文含义猜测其中的含义是行不通的。
另外有许多词比如negotiate这比较常见的是“谈判”的意思，但是当它出现在“negotiate a bad turn”这个词组中，译成“谈判”就不合适，查查词典就知道是“顺利通过”的意思，所以翻译时选择在具体语言环境中最恰当。
一本好的科技词典可以成为你的良师益友，为此笔者推荐《英汉道路词典》《汉英科技大词典》两本较好的词典。
二、科技英语中大量使用被动语态被动语态在普通英语中是最基本的语法，简单易学。
科技英语中大量使用被动语态，不是为了追求文章语言的艺术美，而是为了讲求叙述文章的客观，语言简洁，结构严谨，和普通英语文章有着显著不同，加深读者对所叙述事物的深刻印象，摒弃不必要的东西。
例如：1. Most primary highways are built and cared for by state governments. 大部分主要的公路都是由联邦政府建造和管理。
科技英语外文翻译之英文篇
Microcontroller Based System for theMeasurement of Dielectric Constant inLiquidsCh.V.V.Ramana and K.MalakondaiahDepartment of Instrumentation and University Science InstrumentationCentre,Sri Krishnaevaraya University,Anantapur,IndiaAbstract:A microcontroller based system using 89c51microcontroller for the measurement of dielectric constant in liquids has been designed and developed.It is based on the principle that the change in frequency of an XR–2206function generator,when the liquid forms the dielectric medium of the dielectric cell,is measured with a microcontroller.Atmel’s AT89C51microcontroller is used in the present study.Further,an LCD module is interfaced with the microcontroller in 4-bit mode,which reduces the hardware complexity.Software is developed in C using Ride’s C-cross compiler.The instrument system covers a wide range of dielectric constants for various liquids at various concentrations and at different temperatures.The system is quite successful in the measurement of dielectric constant in liquids with an accuracy of +0.2%.The paper deals with the hardware and software details.Keywords:Dielectric constant,XR-2206Function generator,Frequency measure-ment,C using Ride’s C-cross compiler and 89C51MicrocontrollerINTRODUCTIONThe dielectric constant is a property of major concern in understanding acid-base behaviour in various solvents.A “dielectric”is a substance that can sustain an electric field and acts as an insulator.Some liquids and gases can serve as good dielectric materials,having a special property of storing and dis-sipating electrical energy when subjected to electromagnetic fields.Dry air is Address correspondence to K.Malakondaiah,Department of Instrumentation and University Science Instrumentation Centre,Sri Krishnaevaraya University,Anantapur 515003,India.E-mail:ramana6@Instrumentation Science and Technology ,35:599–608,2007Copyright #Taylor &Francis Group,LLCISSN 1073-9149print /1525-6030onlineDOI:10.1080/10739140701651581599an excellent dielectric.Dielectric measurements are useful for detecting explosives,plastic and metal weapons,drugs,chemical agents,and biological agents.The dielectric constant 1of a liquid is defined as the ratio of the electrical capacitance of a cell when the liquid /solution forms the dielec-tric medium (C s )to the capacitance of the cell when air forms the dielectric medium (C 0)at a given temperature,which is represented by the following equation:1¼ðC s Þ=ðC 0Þð1ÞThe dielectric cell consists of two parallel metallic plates which act as electrodes.The cell acts as a capacitor,while the liquid acts as a dielectric medium.The cell has to be first standardized to measure the dielectric constants of unknown solutions.This is accomplished by considering a pure liquid,such as benzene,as the reference liquid.The dielectric constant of an unknown liquid (1x )can be determined by measuring the capacitance of the cell in air (C 0),the capacitance of cell in the reference liquid (C r ),such as benzene,and the capacitance of the cell in the liquid whose dielectric constant has to be measured (C x ),using the relationship:1x ¼1þ½ðC 0ÀC x Þ=ðC 0ÀC r Þ Âð1r À1Þð2Þwhere 1r is the dielectric constant of the reference liquid.The dielectric constant of a material contains detailed information about the physical and chemical composition and structure.[1]Nowadays,the popularity of microcon-trollers is increasing,due to the fact that they are being used in all types of instruments and in embedded environments.In the present study,the technique utilizes frequency measurement for determination of capacitance using the microcontroller as a tool,while most of the conventional techniques measure the capacitance using bridge methods.PRINCIPLEThe IC XR–2206is a function generator chip.It acts as an RC oscillator.The frequency of oscillations depends on the values of timing resistor R and timing capacitor C.The value of R is kept constant.The dielectric cell acts as a capacitor C that varies with the dielectric medium.Consequently,the frequency of the oscillator also changes.The measurement of the frequency of the oscillator enables one to measure the value of the capacitance of the cell and,thus,the dielectric constant of the medium.In the present study,with suitable interface of the oscillator circuit with a 89C51microcontroller,the frequency of the oscillator is measured.The dielectric constant of the medium is computed using Eq.(2)and is displayed on the LCD.Ch.V.V.Ramana and K.Malakondaiah 600EXPERIMENTALInstrumentationHardware DesignThe block diagram of the microcontroller based system for the measurement of dielectric constant in liquids is shown in Fig.1.A schematic diagram which contains more details is shown in Fig.2.The designed cell is connected between pins 5and 6of THE XR-2206using A BNC connector.The dielectric cell acts as a capacitor C whose capacitance can be measured in terms of frequency.The block A of Fig.2consists of the XR-2206function generator.The output of the RC oscillator (the square wave output (pin 11)is an open collector and,hence,it needs a pull up resistor to V cc .Connecting a 10K resistor between pins 11and V cc ,makes the square wave output to be TTL compatible.In the present study,the XR-2206function generator generally operates at 1MHz frequency.But,the 8051microcontroller can measure the frequency accurately up to a few hundred kilohertz frequency.Hence,the divide counter shown in block B of Fig.2is used.The output of the RC oscillator is given to the clock input of the 74LS90IC [3]decade counter;(which acts as a divide counter (410,412,and a 4-bit binary counter)that divides the RC oscillator output by 10times.The output of the 74LS90is given to the timer 0external input,which is available on the micro-controller (port 3).The microcontroller counts the clock pulses that are given from the 74LS90over an interval of 1sec,which gives the frequency of the oscillator.Block C of Fig.2consists of an LM335[4]which is used as a sensor to measure the temperature of the solution.It also consists ofthe Figure 1.Block diagram of microcontroller based system for the measurement of dielectric constant in liquids.Microcontroller Based System 601hardware that amplifies the signal from the temperature sensor.The output of the temperature unit is given to the analog-to-digital converter (IC 0809)which is shown in block D of Fig.2.The IC 0809is a monolithic CMOS device with an 8-bit analog-to-digital converter,8-channel multiplexer,and microprocessor compatible control logic.[5]The 8-bit A /D converter uses suc-cessive approximation,which can make 100conversions per microsecond at a clock rate 120KHz.The 0809operates 0to 5V input range with single 5V power supply.It is used to convert the analog temperature into digital values.Block E of Fig.2is an AT89C51microcontroller from the Atmel Company.[6]It is a low-power,high-performance CMOS 8-bit microcomputer with 4K bytes of flash programmable and erasable read only memory (PEROM).It has four parallel ports,two 16-bit timers /counters,six interrupt sources,and one programmable serial port,with low powerideal Figure 2.Schematic diagram of microcontroller based system for the measurement of dielectric constant in liquids.(continued )Ch.V.V.Ramana and K.Malakondaiah 602and power down modes;it has the facility of three-program memory lock.The on-chip flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer.All ports are used (port 1is used for LCD display,port 2is for ADC,port 0is used for control signals (that are RS,RW,and EN for LCD display,and SC,ALE and EOC for ADC),port 3(one line is used)is used for frequency measurement.Block F of Fig.2is a two-row 16characters LCD display from ODM;[7]it is interfaced with the microcontroller through port 1to display the measured data and results.The interfacing of the ADC with the microcontroller is shown in Fig.2(a)[continu-ation of Fig.2].Interfacing of the Oscillator with the MicrocontrollerThe frequency of oscillation f 0is determined by the external timing capacitor C (across pins 5and 6)and the timing resistor R (connected to either pin 7or8).The frequency is given by:f 0¼1=R ÃC ð3ÞThe frequency f 0can be adjusted by varying either R or C.In the present study,the timing resistor R is kept constant.Since the timing capacitor C is to be maintained at a minimum of 100pf,a capacitor of value 100pf is connected in parallel with the dielectric cell.TheFigure 2.Continued.Microcontroller Based System 603designed cell is connected between pins5and6of the XR-2206using a BNC connector.The dielectric cell acts as a capacitor C whose capacitance can be measured in terms of frequency using the following equation:C¼1=RÃf0ð4ÞSoftwareSoftware is developed in C using Ride’s(Raisonance Integrated Develop-ment Environment)C-cross compiler to initialize the LCD display and measure the frequency,capacitance,dielectric constant,and temperature. After development,the codes are stored in the program memory(flash EPROM)of the AT89C51microcontroller by using the Atmel programmer and the program is executed.Theflow chart of the program is presentedFig.3.Calibration and MeasurementThe instrument is calibrated and measured following the procedure mentioned below.1.Clean the dielectric cell,dry it,and keep it in a beaker containing air.2.Connect the cell to the circuit as shown in Fig.2.3.Switch on the system and activate the software.4.The system measures and displays the frequency,along with tempera-ture and,in turn,the capacitance of the cell using Eq.(4).Make a note of the values.5.Keep the reference liquid (benzene in the present study)in the cell.6.Repeat the steps from (2)to (4).7.Place the unknown liquid in the cell.8.Repeat the steps from (2)to (4).9.Then,calculate the dielectric constant of the unknown liquid using Eq.(2).10.Note the readings of the dielectric constant of unknown liquids along with temperature.RESULTS AND DISCUSSIONThe performance of the microcontroller-based system for the measurement of dielectric constant in liquids is tested with some liquids at 308C.The samples are selected to cover a wide range.The results are presented in Table 1.The results of the present study are in good agreement with the literature values.The dielectric constant measurements for the binary liquid mixtures(1)benzene þnitrobenzene;(2)nitrobenzene þchlorobenzene;and (3)nitrobenzene þcyclohexanone for various concentrations (mole /L)at 308C were made.The results are graphically represented in Fig.4.Table I.Dielectric constants of pure liquids at 308CSamplePresent work Literature Reference Toulene2.46 2.40[9]Chlorobenzene5.96 5.91[10]5.90[9]Cyclohexanone17.9618.2[9]Acetone20.3020.35[9]Methanol32.5632.6[9]Nitrobenzene 34.8934.81[12]34.80[11]Ch.V.V.Ramana and K.Malakondaiah 606CONCLUSIONThe hardware and software features of a microcontroller based system for the measurement of dielectric constant in liquids are described.The necessary software is developed in C,using Ride’s C-cross compiler.The system is quite successful for the measurement of dielectric constants in liquids with an accuracy of +0.2%.The measurement of dielectric constant,over a wide range,is a special feature of the present study.ACKNOWLEDGMENTSThe authors are thankful to M /S Mittal Enterprises,New Delhi for providing the necessary help to carry out this work.REFERENCES1.Hoppe,W.Bio Physics ;Springer-Verlag:New York,1983.2.XR-2206function generator chip Datasheet,Exar ;the Analog Plus Company,1997.3.IC 74LS90Decade Counter Datasheet ;Motorola,1999.4.Data Acquisition Data Book ;National Semiconductor,1993.5.IC 08098-Bit Analog to Digital Converter Datasheet ;National Semiconductor,1999.6.IC AT89C518-Bit Microcontroller with 4K Bytes Flash Datasheet ;Atmel Company,2000.7.ODM LCD User Manual ;1998.8.Rajendran,A.;Neelamegam,K.An instrument for measurement of dielectric constant of liquids using 8031Microcontroller.Bull.Electrochem.2004,20(2),59–62..This site is for dielectric constanttables.Figure 4.Concentration versus dielectric constant for three binary liquid mixtures.Microcontroller Based System 60710.International Critical Tables of Numerical Data in Physics,Chemistry and Tech-nology ;USA,1933.11.Weissberger,A Ed.,Technique of Organic Chemistry .Vol.III;Interscience:New York,1967.12.Hand Book of Chemistry and Physics ,76th Edn.;The Chemical Rubber Co:Cleveland,Ohio,1995.Received November 17,2006Accepted March 13,2007Manuscript 1605Ch.V.V.Ramana and K.Malakondaiah608。
科技英语词汇的翻译
• 常见科技词汇后缀：
-ness -tion -ity -ism
表示性质、状态 表示动作、状态 表示性质、状态 表示主义、学说
oneness, thoughtfulness, carelessness examination, realization, decoration reality, purity, gravity, formality atomism, criticism, socialism
在这种情况下，可能会损伤火箭发动机机体。
• He walks when he might take a taxi.
虽然他可坐出租车，却还是步行。
• The volcano has not been active for thousands of years. It is inactive.
这座火山有几千年没有爆发了，它是座死
• 翻译误区：科技英语翻译的难点是专业术语的翻
译，有一些词汇看起来很简单，但是在科技文章 中则产生了其他的含义。
英语 pig cock coat hand tooth
常见意义 猪
公鸡 外衣
手 牙齿
专业术语含义 金属锭块 吊车 镀层
手柄、指针 粗糙面
词义的引申
• 1. 技术性引申 使译文中涉及科学技术概念的词语符合技 术语言规范。
• BBS：Bulletin Board System 电子公告牌系统 • DNA：deoxyribonucleic acid 脱氧核糖核酸 • UFO：Unidentified Flying Object 不明飞行物 • VCD：Video Compact Disc 影音光盘（影碟） • AC：alternating current 交流电 • DC：direct current 直流电
经典翻译范文之科技篇中英文对照
中国热门科技词汇科学发展观concept of scientific development全民科学文化素质scientific and cultural qualities of the entire people 发展科技scientific and technological advancement科教兴国revitalize China through science and education 农业技术agricultural technology[扩展]白色农业 white agriculture （microbiological agriculture and biological cell agriculture）超级杂交水稻super-hybrid rice技术下乡spreading the application of science and technology in rural areas节水农业water-saving agriculture立体农业3-D agriculture农产品加工及转化the processing and commercialization of agro-products 农业科技agro-science农作物良种seeds of high-quality crop农作物新品种选育the selection and breeding of new crops 生态农业environmental-friendly agriculture无土栽培soil -less cultivationBP机，传呼beeper, pager背投屏幕rear projection screen不明飞行物unidentified flying object （UFO）操作系统operating system产品科技含量technological element of a product创新innovation电话会议teleconference电话留言机answering machine对讲机talkie and walkie多媒体multimedia二期the second phase防抱死系统ABS （anti-lock braking system）孵化器incubator高产优质high yield and high quality高技术产业化apply high technology to production高科技板块high-tech sector高科技园high-tech park个人数字助理PDA （personal digital assistant）工业园区industrial park国家质量技术监督局the State Bureau of Quality and Technical Supervision 国家重点实验室national key laboratories火炬计划Torch Program （a plan to develop new and high technology）计算机中央处理器central processing unit（CPU）技术产权technology property right技术交底confide a technological secret to someone.技术密集产品technology-intensive product交叉学科interdisciplinary branch of science科技成果转化为生产力 transfer of scientific and technological achievements into productive forces科技含量technology content科技基础设施science and technology infrastructure科技是第一生产力Science and technology constitute a primary productive for ce科技体制改革reform of the science and technology management system科技与经济脱节science and technology are out of line from the economy科教兴国rejuvenate the country through science and education可持续发展战略strategy of sustainable development纳米nanometer三峡水利枢纽工程the key water control project at the Three Gorges on the Yangtze River物种起源origin of species新兴学科new branch of science研究成果research results在孵企业incubated enterprises自动取款机automatic teller machine （ATM）自然科学与社会科学的交叉融合integration of natural and social sciencesIT 信息技术[扩展]信息港info port信息高地information highland信息高速公路information superhighway信息革命information revolution信息含量information content信息化informationization信息技术处理ITA - Information Technology Agreement 信息检索information retri办公自动化OA （Office Automation）笔记本电脑laptop / notebook / portable computer 电脑病毒computer virus电脑犯罪computer crime电子管理e-management电子货币e-currency电子商务e-business; e-commerce电子商务认证e-business certification电子邮件E-mail非对称数字用户环路ADSL （Asymmetrical Digital Subscriber Loop）高速宽带互联网high-speed broadband networks公告板BBS （bulletin board system）光盘杂志CD-ROM magazine广域网WAN （wide area net word）汉字处理软件Chinese character processing software黑客hacker计算机2000年问题Y2K problem计算机辅助教育CAI -computer assisted instruction计算机辅助设计CAD-computer assisted design计算机合成制造CAM-computer assisted manufacturing计算机中央处理器CPU - central processing unit超文本传送协议hypertext transfer protocol （HTTP）界面interface金融电子化computerized financial services局域网LAN - local area network互联网服务提供商ISP （Internet Service Provider）全球移动通信系统（全球通）global system for mobile communications （GSM）刻录机CD burner宽带接入broadband access宽带网broadband networks内联网、局域网（计算机）Intranet垃圾邮件junk mail千年问题、千年虫millennium bug; Y2K bug 人工智能AI - artificial intelligence人机交互human - computer interaction人机交互human-computer interaction虚拟人visual human虚拟网virtual net虚拟网virtual net虚拟现实virtual reality虚拟银行virtual bank因特网服务提供商ISP- internet service provider万维网World Wide Web（WWW）应用软件internet applications域名domain在线on line掌上电脑palm computer政府上网工程Government Online Project只读存储器read-only-memory （ROM）智能感知技术perceptive technology智能终端intelligent terminal中文信息处理系统Chinese information processing system数码科技digital technology高保真Hi-Fi （High Fidelity）高清晰度电视high definition TV （HDTV）光谷optical valley光通讯optical communication蓝光光盘Blue -ray Disc数码港cyber port数字地球digital globe数字蜂窝移动通信digital cellular mobile telecommunications三维电影three-dimensional movie三维动画three-dimensional animation[详析] “蓝光光盘”利用蓝色的激光束来刻录数据。
科技英语翻译(1)
ENGLISH FOR SCIENCE AND TECHNOLOGY
Historically，“three peaks”in translation movements：东汉至唐宋的Buddhism scripture 的翻译、明末清初的科技翻译、鸦片 战争至‘五四“ 的西学翻译。（ First Opium War (Britain’s invasion of China, 1840-1842） In terms of scope, quality, and contribution to the development of the nation, the current one is unprecedented.
形象生动,句式简单,强烈的审美意识， 文字生动而感人。
专业术语,正式的客观描述词汇,较长的
名词化结构,客观事实,文字严谨而客观。
2. 与英语口语文体的对比 An old lady who was listening exclaimed: It beats all how folks do things nowadays. When I was a gal, they made a hole in each end of an egg and sucked. A young lady back home from school was explaining. “ Take an egg.” She said, “ and make a perforation in the base and a corresponding one in the apex, then apply the lips to the aperture, and by forcibly inhaling the breath, the shell is entirely discharged of its contents.”
科技英语中英文对照翻译
mobile and cellular radio移动和细胞广播in comparison to the relative stability and modest technical developments which are occurring in long haul wideband microwave communication systems there is rapid development and expanding deployment of new mobile personal communication system. These rang from wide coverage area pagers,for simple data message transmission,which employ common standards and hence achieve contiguous coverage over large geographical areas,such as all the major urban centres and transport routes in Europe,Asia or the continental USA.This chapter discusses the special channel characteristics of mobile systems and examines the typical cellular clusters adopted to achieve continuous communication with the mobile user.It then highlights the important properties of current,and emerging,TDMA and code division multiple access(CDMA), mobile digital cellular communication systems.Private mobile radioTerrestrial mobile radio works best at around 250 MHz as lower frequencies than this suffer from noise and interference while higher frequencies experience multipath propagation from buildings,etc,section 15.2.In practice modest frequency bands are allocated between 60MHz and 2GHz. Private mobile radio(PMR) is the system which is used by taxi companies,county councils,health authorities,ambulance services,fire services,the utility industries,etc,for mobile communications.PMR has three spectral at VHF,one just below the 88 to 108 MHz FM broadcast band and one just above this band with another allocation at approximately 170MHz.There are also two allocations at UHF around 450MHz. all these spectral allocations provide a total of just over 1000 radio channels with the channels placed at 12KHz channel spacings or centre frequency offsets. Within the 12khz wide channal the analogue modulation in PMR typically allows 7khz of bandwidth for the signal transmission.when further allowance is made for the frequency drift in the oscillators of these systems a peak deviation of only 2 to 3 khz is available for the speech traffic. Traffic is normally impressed on these systems by amplitude modulation or frequency modulation and again the receiver is of the ubiquitous superheterodyne design,Figure 1.4. A double conversion receiver with two separate local oscillator stages is usually required to achieve the required gain and rejection of adjacent channel signals.One of the problems with PMR receiver is that they are requiredto detect very small signals,typically—120dBm at the antenna output,corresponding to 0.2 uV,and,after demodulating this signal,produce ann output with perhaps 1W of audio equipment, the first IF is normally at10.7MHz and the second IF is very orten at 455KHz . unfortunately,with just over 1000 available channels for the whole of the UK and between 20000and30000issued licences for these systems,it is inevitable that the average busuness user will have to share the allocated channel with other companies in their same geographical area.There are various modes of operation for mobile radio communications networks, the simplest of which is singal frequency simplex. In simplex communication, traffic is broadcast, or one way. PMR uses half duplex(see later Table 15.3) where, at the end of each transmission period, there is a handover of the single channel to the user previously receiving, in order to permit them to reply over the same channel. This is efficient in that it requires only one frequency allocation for the communication link but it has the disadvantage that all units canhear all transmissions provided they are within rage of the mobile and frequencies are allocated for the transmissions. One frequency is used for the forward or downlink, namely base-to-mobile communications. This permits simultaneous two-way communication and greatly reduces the level of interference, but it halves other’s transmissions, which can lead to contention with two mobiles attempting to initiate a call, at the same time, on the uplink in a busy syetem.Although PMR employs relatively simple techniques with analogue speech transmission there have been many enhancements to these systems over the years . Data transmission is now in widespread use in PMR systems using FSK modulation. Data transmission also allows the possibility of hard copy graphics output and it gives direct access to computer services such as databases, etc. Data prembles can also be used, in a selective calling mode, when initiating a transmission to address a special receiver and thus obtain more privacy within the system.15.4.5 Trunked radio for paramilitary use集群无线电的军事使用Another related TDMA mobile radio standard is the European trunked radio(TETRA)network which has been developed as part of the public safety radio communications service(PSRCS) for use by police, utilities, customs office, etc. TETRA in fact is part of wider international collaborations for paramilitary radio use.In these portable radios there is a need for frequency hopping (FH) to give an antieavesdropping capability and encryption for security of transmission to extend military mobile radio capabilities to paramilitary use, i.e. for police, customs and excise offices, etc. these capabilities are included in the multiband interteam radio for the associated public safety communications office in the USA while Europe has adopted the TETRA standard.TETRA is essentially the digital TDMA replacement of the analogue PMR systems. The TETRA standard has spectrum allocations of 380 to 400 and 410 to 430MHz, with the lower band used for mobile transmissions and the upper band for base station use. TETRA mobile have 1 W output power and the base stations 25 W using error with the data throughput rate varying, to meet the required quality of service. TETRA can accommodate up to four users each with a basic speech or data rate of 7.2kbit/s. with coding and signaling overheads, the final transmission rate for the four-user slot is 36 kbit/s. this equipment is large and more sophisticated than a commercial cell phone, and it sells for a very much higher price becase the production runs are much small. However, its advanced capabilities are essential for achieving paramilitary communications which are secure from eavesdropping.15.5 Code division multiple accessAnalogue communication systems predominantly adopt frequency division multiple access (FDMA), where each subscriber is allocated a narrow frequency slot within the available channel. The alternative TDMA(GSM) technique allocates the entire channel bandwidth to a subscriber but constrains the subscriber but constrains the subscriber to transmit only regular short bursts of wideband signal. Both these accessing techniques are well established for long haulterrestrial, satellite and mobile communications as they offer very good utilization of the available bandwidth.15.5.1The inflexibility of these coordinated accessing techniques has resulted in the development of new systems based on the uncoordinated spread spectrum concept. In these systems the bits of slow speed data traffic from each subscriber are deliberately multiplied by a high chip rate spreading code, forcing the low rate (narrowband data signal) to fill a wide channel bandwidth.15.7.2 3G systemsThe evolution of the third generation (3G)system began when the ITU produce the initial recommendations for a new universal mobile telecommunications system(UMTS)[www.] The 3G mobile radio service provides higher data rate services ,with a maximum data rate in excess of 2Mbit/s, but the achievable bit rate is linked to mobility. Multimedia applications encompass services such as voice, audio/video, graphics, data, Internet access and e-mail. These packet and circuit switched services have to be supported by the radio interface and the network subsystem.Several radio transmission technologies(RTT) were evaluated by the ITU and adopted into the new standard, IMT-2000. the European standardization body for 3G, the ETSI Special Mobile Group, agreed on a radio access scheme for 3G UMTS universal terrestrial radio access(UTRA) as an evolution of GSM. UTRA consists of two modes : frequency division duplex(FDD) where the uplink and downlink are transmitted on different frequencies; and time division duplex(TDD) where the uplink and downlink are time multiplexed onto the same carrier frequency. The agreement assigned the unpaired bands (i.e. for UTRA TDD ). TD-CDMA is a pure CDMA based system. Both modes of UTRA have been harmonised with respect to basic system parameters such as carrier spacing, chip rate and frame length to ensure the interworking of UTRA with GSM.The 3G proposal were predominantly based wideband CDMA(WCDMA) and a mix of FDD and TDD access techniques. WCDMA is favoured for 3G in poor propagation environments with a mix of high modest speed data traffic. It is generally accepted that CDMA is the preferred accesstechnique and, with the increase in the data rate, then the spreading modulation needs to increase to wideband transmission.WCDMA is based on 3.84Mchip/s spreading codes with spreading ratio, i.e. , K values, of 4-256 giving corresponging data ratas of 960-15 kbit/s. the upper FDD uplink band I from 1920-1980 MHz is paired with a 2110-2170 MHz downlink. In addition uplink bands II & III at 1850-1910 MHz and 1710-1785 MHz are also paired, respectively, with 1930-1990 MHz and 1805-1880 MHz allocations. the system is configured on a 10 ms frame with 15 individual slots to facilitate TDD as well as FDD transmissions. TDD is more flexible as time-slots can be dynamically reassigned to uplink and downlink functions, as required for asymmetric transfer of large files or video on demand traffic. 3G WCDMA systems use an adaptive multirate speech coder with encoded rates of 4.75-12.2 kbit/s. receivers commonly use the easily integrated direct conversion design, in place of the superheterodyne design . receiver sensitivities are typically -155dBm.The 3GPP2 standard aims to achieve a wide area mobile wireless packet switched capability with CDMA2000 1×EV DO revision A (sometimes called IS-856A). Here 1×refers to the single carrier 1.25 Mchip/s system. It achieves a 3.1 Mbit/s downlink and a delay sensitive services. The 3GPP standard has gone through many release with R4 in 2001 which introduced packet data services and R6 in 2005 to further increase the available data transmission rate . R6 pioneers the use of high-speed downlink packet access and multimedia broadcast multicast services which offer reduced delays and increased uplink data rates approaching 6 Mbit/s.In parallel with the European activities extensive work on 3G mobile radio was also performed in Japan. The Japanese standardisation body also chose WCDMA, so that the Japanese and European proposals for the FDD mode were already aligned closely. Very similar concepts have also been adopted by the North American standardization body.In order to work towards a global 3G mobile radio standard, the third generation partnership project(3GPP), consisting of members of the standardization bodies in Europe, the USA, Japan, Korea and China, was formed. It has merged the already well harmonized proposals of the regional standardization bodies to work on a common 3G international mobile radio standard, still called UTRA. The 3GPP Project 2(3GPP2), on the other hand, works towards a 3G mobile radio standard based on cdmaOne/IS-95 evolution, originally called CDMA2000.比起相对稳定、适度的技术发展是发生在宽带微波通信系统,有长期快速发展和扩大部署的新的移动个人通讯系统。
科技英语翻译
科技英语翻译 1.1 翻译的标准第1节翻译练习1 The power plant is the heart of a ship. The power unit for driving the machines is a 50-hp induc tion motor. 动力装置是船舶的心脏。
驱动这些机器的动力装置是一台50马力的感应电动机。
第1节翻译练习2 Semiconductor devices, called transistors, are replacing tubes in many applications. Cramped co nditions means that passengers’ legs cannot move around freely. All bodies are known to posse ss weight and occupy space. 半导体装置也称为晶体管 在许多场合替代电子管。
我们知道 所有的物体都有重量并占据空间。
空间狭窄,旅客的两腿就不能自由活动。
第1节翻译练习3 The removal of minerals from water is called softening. A typical foliage leaf of a plant belonging to the dicotyledons is composed of two principal parts: blade and petiole. 去除水中的矿物质叫做软化。
双子叶植物典型的营养叶由两个主要部分组成 叶片和叶柄。
1.2 对译者的要求第4节翻译练习1 Einstein’s relativity theory is the only one which can explain such phenomena. All four (outer planets) pro bably have cores of metals, silicates, and water. 爱因斯坦的相对论是能解释这种现象的唯一理论。
科技英语
②并非所有被动语态句子都能起到突出新信息的作用。 基于以上观点，现代科技工作者提倡用主动语态撰写科 技文章。例如《Science》和《Nature》等国际著名刊物在征 稿要求中提出稿件应尽量采用主动语态写作。
翻译例句 本文介绍了热能制冷技术和燃料电池的工作原理及其特 点。针对燃料电池汽车余热浪费大的特点，提出了利用其余热 制冷为燃料电池汽车空调提供冷源的方法，并对其可行性进行 了研究。 译文1：In this paper, the work principles and features of fuel cell as well as refrigeration technique driven by heat energy are introduced. Considering the present fact that a large amount of heat of fuel cell automobile is wasted, the program that cold source is provided for automobile airconditioner with the refrigeration driven by the heat has been proposed and the feasibility of it has been studied. 第一句使用被动语态，该句主语由17个单词构成，而谓语 只有2个单词，造成头重脚轻的结构。第二句为了使用被动语 态，出现了“悬垂分词”，不合英语语法。
It was unsatisfactory for industry to depend on supplies coming from so far away from the industrial areas of Europe. It was always possible that wars or shopping trouble could stop supplies.