讲义专业英语1

Physics in EnglishThe scientist does not study nature because it is useful;he studies it because he delights in it,and he delights in it because it is beautiful.If nature were not beautiful,it would not be worth knowing,and if nature were not worth knowing,life would not be worth living."------ Henri PoincareDepartment of PhysicsSchool of scienceXian Technological University 2012.9Chapter 1 What is Physics?Physics is natural science studying nature's LawsPhysics was called natural philosophy and fundamental science.The history of physicsThe history of physics encompasses two broad time periods in which classical physics and modern physics developed. Classical physics developed between 1600 and 1900. It embraces the general areas of physics known as mechanics, thermodynamics, and electromagnetism, culminating in relativity. Modern physics began developing between about 1890 and 1930, when it was realized that classical physics could not account for the newly discovered behavior of nature at the atomic and molecular level. Modern physics includes the theory of relativity as well as quantum mechanics and most of the subsequent new physics discovered and developed during the 20th century.Classical physicsClassical physics includes the traditional branches and topics that were recognized and well-developed before the beginning of the 20th century—classical mechanics, optics, thermodynamics, and electromagnetism. Classical mechanics is concerned with bodies acted on by forces and bodies in motion and may be divided into statics (study of the forces on a body or bodies at rest), kinematics (study of motion without regard to its causes), and dynamics (study of motion and the forces that affect it); Acoustics, the study of sound, is often considered a branch of mechanics because sound is due to the motions of the particles of air or other medium through which sound waves can travel and thus can be explained in terms of the laws of mechanics. Among the important modern branches of acoustics is ultrasonics, the study of sound waves of very high frequency beyond the range of human hearing. Optics, the study of light, is concerned not only with visible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light. Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy. Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamics with moving charges, and magnetostatics with magnetic poles at restThe Emergence of Classical PhysicsClassical mechanics has its roots in the work of Johannes Kepler, who, between 1600 and 1619, became the first person to describe quantitatively and accurately the elliptic paths of the planets around the Sun.The problem of the shape of the planetary orbits was not easy to solve, because all historical observations of the planets were made from the Earth, itself a moving planet. Although a crude heliocentric(Sun-centered) model of the solar system using circular orbits was proposed by the Greek astronomer Aristarchus in the third century B.C. and resurrected by Copernicus in 1542,the planetary positions predicted by Copernicus were not as accurate as those found using Ptolemy's complicated geocentric (Earth-centered} model of the second century A.D.The pure Copernican model was inaccurate because Copernicus refused to abandon the flawed concept of early Greek thought that the natural path of a moving "perfect" celestial object, such as a planet, had to be in the shape of the "perfect" geometrical figure---a circle---with the planet moving at constant speed. a scientist living at the time of Copernicus would have been forced to reject the Copernican theory with its circular planetary orbits, since they did not account for the observed motions of the planets as accurately as the existing, but more complicated, geocentric theory of Ptolemy.The change from the accurate but complex Ptolemaic geocentric model of the solar system to the accurate and simple heliocentric model of Kepler illustrates the characteristics of a good theory. With Kepler's work, accuracy and simplicity blossomed simultaneously from the heliocentric hypothesis. Kepler's model and mathematical methods began the development of physics as we know it. His work was a watershed of quantitative thought and a new worldview.Observation of nature and experimental results typically precede the general theories that account for them. The extensive observations of the planets by Tycho Brahe just prior to 1600 provided Kepler with the data he needed to model the solar system accurately and precisely。

专业英语部分习题答案参考b--吡啶 pyridine 巴比妥酸:barbituric acid 比电导conductance不规则的:irregular 崩解剂disintegrantc--萃取 extraction 成团:agglomeration 测量仪measurement 肠液:intestinal fluidd--胆固醇cholestero 对映体:enantiomer 电极electrode 代谢:metabolismf--反相渗透reverse osmosis 分布:dispositiong--构象:conformation 固化:solidizej--甲苯 toluene 静脉注:intravenous injection 挤压:compress聚集:aggregate 胶囊capsulel--粒子:particle 立体选择性:stereoselectivity 利用率:availabilitym--灭菌产品sterile products n--粘合剂adhesivep--偏振光:polarized light 片剂tablet 配剂elixir 排泄:excretionq--起始原料starting materials(raw materials) q醛 aldehyder--溶解度:solubility 乳剂emulsion 润滑剂lubricants--释放:release 渗液solution 生物膜:biologic membrane 生物碱alkaloid, t---糖浆syrup 甜味剂sweetenerw--丸剂pill 微生物microorganism 胃液:gastric fluid 稳定态:steady-statex--旋光异构现象:optical isomerism 悬浮液suspension 香味剂flavor 稀释剂diluent形状:shape 吸收:absorption 消除:eliminationy--胰岛素 insulin 压片:tablet compressionz--中间体intermediate 重结晶 recrystallization 左旋:levorotation蒸馏distillation 组织tissuea--asymmetric carbon不对称碳 absorption吸收 action动作 adhesive粘合剂c--contamination污染 chirality:手性 compress压缩 composite合成的compressibility:可压缩性 compaction:压紧 contamination specialize特殊污染conductivity电导率 control:控制 clinical:临床的d-- design:设计 dry:干燥 delivery:传送e-- extend:延长 epoxide:环氧化物f-- formulation:制剂 fluidity:流动性 function:功能g-- geometric isomerism:几何异构h-- hormone激素 hydrolysis diastereoisomer:水解非对映异构体heterogeneous catalyst多相催化剂，i-- irrigating冲洗m-- metabolite代谢物 medication药物治疗 medicine内服药 mill:研磨measure尺寸 mix:混合 microorganisms微生物o-- ophthalmic眼药p-- polysaccharide多糖 peptide肽 plasma血浆 penicillin青霉素，precursor:前体 partition coefficient:狭义分配系数 pharmaceutical制药的 parenteral注射药物 pycogens热源 procedure:程序q-- quality性质 quantity数量s-- steroid甾类 steric effect:空间效应 stereoselectivity:立体选择性screening:过筛 sustain :维持t-- treat治疗 therapy:治疗u--uniformity目标 v--vaccine疫苗Unit1 P7Answer the following questions:How many groups can pharmaceutical agents be split into depending on their production or origin?①totally synthetic materials(synthetics)②natural products③products from partial syntheses(semi-synthetic products)(2)Can you illustrate any significant examples of pharmaceutical agents obtained by total synthesis?L-amine,chleramphomical,caffeine,Dopamine,Epinephrine,Lerodapa,peptide,hormones.Prestaglanding,P_Pouricollamine,Vincamine,(3)What is the difference between the synthetic drugs and traditional Chinese herbal medicine?synthetic drugs include the most important of synthetics and semi-sythetic products, however, natural products are frequently needed as starting materials or intermediates for important synthetic products.2、生物碱4、Introduction of Nucleic acidsNucleic acids are polyanionic molecules of high molecular weight. These polymers are composed of a sequence of subunits or nucleotides so that the whole is usually termed a polynucleotide. The nucleic acids are of two main varieties, ribonucleic (RNA) and deoxyribonucleic (DNA). DNA is found primarily in the chromatin to the cell nucleus, whereas 90% of RNA is presented in the cell cytoplasm and 10% in the nucleolus. The two classes of nucleic acids are distinguished primary on basis of the five-carbon atom sugar of pentose present. Two general kinds of bases are found in all nucleic acids. One type is a derivative of the parent compound purine. Principle examples are guanine and adenine. The second class of bases found in all nucleic acid is derived from the parent compound pyrimidine.介绍核酸核酸是超高分子量聚阴离子分子。

地理专业英语地理专业英语geography 地理geographer 地理学家hemisphere 半球meridian 子午线，经线parallel 平行圈，纬线latitude 经度longitude 精度elevation 海拔altitude 高度temperate latitudes 温带地区horizon 地平线equator 赤道tropics 热带地区Arctic 北极Antarctic(Antarctica) 南极expedition 探险time zone 时区topography 地形，地形学plain 平原plateau (highland) 高地lowland 低地basin 盆地cavern (cave) 洞穴terrain 地域subterranean ( underground) 地底下coastland 沿海地区island 岛屿continental island 大陆岛volcanic island 火山岛coral island 珊瑚岛islet 小岛peninsular 半岛continent 大陆continental shelf 大陆架ranges 山脉valley 峡谷canyon 峡谷channel (strait) 海峡remote-sensing 遥感的terrestrial 地球的，陆地的terrestrial heat (geothermal) 地热terrestrial magnetism (geomagnetism) 地磁continental drift 大陆漂移学说sea-floor spreading 海床扩展evaporation 蒸发salinity 含盐度ocean bottom 海床sediment 沉淀物，沉积物tropical 热带的temperate 温带的frigid 寒带的formation 形成frost heaving 冻胀现象fieldstone 卵石physical geography 自然地理economic geography 经济地理geopolitics 地理政治论ethnography 民族志cosmography 宇宙志cosmology 宇宙论geology 地理学toponymy 地名学oceanography 海洋学meteorology 气象学orography 山志学hydroaraphy 水文学vegetation 植被relief 地形,地貌climate 气候Earth 地球,大地Universe, cosmos 宇宙world 世界globe 地球仪earth, globe 地壳continent 大陆terra firma 陆地coast 海岸archipelago 群岛peninsula 半岛island 岛plain 平原valley 谷地meadow (小)草原prairie (大)草原lake 湖泊pond 池塘marsh, bog, swamp 沼泽small lake 小湖lagoon 泻湖moor, moorland 荒原desert 沙漠dune 沙丘oasis 绿洲savanna, savannah (南美)大草原virgin forest 原始森林steppe 大草原tundra 冻原a horizon 腐殖堆积层aa lava 块熔岩abandoned field 撩荒地abandoned lands 撩荒地abandoned mine 废弃矿山abandoned shoreline 旧岸线aberration 像差abiogenesis 自然发生abiotic factor 非生物因素ablation 水蚀ablation moraine 消融冰碛abnormality 反常aboriginal 土着的abrasion 海蚀abrasion platform 浪蚀台地abrasion shore 浪蚀海岸abrasion surface 浪蚀面abrasion terrace 海蚀阶地abrasive 研磨剂abrupt slope 陡坡abrupt textural change 质地突变abscissa 横坐标absolute age 绝对年龄absolute age determination 绝对年代测定absolute age of groundwater 地下水绝对年龄absolute altitude 绝对高度absolute amplitude 绝对振幅absolute chronology 绝对年代absolute convergence 绝对收敛absolute dating 绝对年代测定absolute error 绝对误差absolute extremes 绝对极值absolute geochronology 绝对地质年代学Word and phrase1. core; mantle; crust 地核；地幔；地壳4. continental crust 大陆地壳5. granite; basalt 花岗岩；玄武岩6. sial; sima 硅铝层；硅镁层7. surface waves; body .. 面波；体波8. epicentre; focus 震中；震源9. lithosphere 岩石圈10. tectonic plate 构造板块11. continetal drift 大陆漂移12. asthenosphere 软流层13. ocean ridge 洋脊14. ocean trench 海沟15. subduction 俯冲作用16. volcanism 火山作用17. fold mountain 褶皱山脉18. fold; fault 褶皱；断层19. sedimentary rocks 沉积岩20. vent 火山口21. lava 熔岩22.volcanic cones 火山锥23. parasitic cone 寄生火山锥24. plug 岩颈25. volcanic ash 火山灰26. mechanical weathering 机械风化27. chemical weathering 化学风化28. freeze-thaw 冻融29. pressure release 卸荷释重30.limestone 石灰岩31. hydrolysis 水解作用32. quartz 石英33. hydration 水合作用34. oxidation 氧化作用35. alluvium 冲击层36. gravel 砂砾37. denudation 剥蚀作用38. precipitation 降水39. climatic zone 气候带40. mid-latitude 中纬度41. semi-arid 半干旱42. tropical wet-dry 热带干湿季气候43. watershed 分水岭44. drainage basin 流域45. regolith 风化层46. soil creep 土壤蠕动47. mass movement 块体运动48. strata 地层49. overland runoff 地表径流50. sheet wash 片状冲刷51. pediment 山前侵蚀平原（山足面）52. rockfall 山崩53. landslide 滑坡54. interception 截流55. evapotranspiration 蒸发和蒸腾总量56. capillary rise 毛管上升57. aeration zone 包气带58. overland flow ; interflow ; base flow 地表径流；壤中流；地下径流59. water table 潜水面（水位）60. basin length; area 流域长度;流域面积61. tributary 支流；62. trunk stream 干流63. drainage density 河网密度64. flood plain 泛滥平原65. coniferous tree 松树67. inselberg 岛状山68. equator 赤道69. monsoon 季风70. storm hydrograph 暴雨水文曲线71. discharge 流量72. peak flow 洪峰流量73. rainfall peak 降水峰值74. precipitation intensity 降水强度75. land use 土地利用76. water-born waste 水成废弃物77. heavy metal 重金属78. climatology 气候学79. urban heat island 城市热岛80. deciduous trees 落叶树81. upper ;middle ; lower reach 上中下游82. vertical erosion 下切侵蚀83. headward erosion 溯源侵蚀84. lateral erosion 侧蚀85. pot-hole 壶穴86. meander 曲流87. ox-bow lake 牛轭湖88. delta 三角洲89. lake basin 湖盆90. levee 天然提91. rill and gully erosion 细沟、冲沟侵蚀92.clay;silt;sand;粘土；粉砂；砂93. suspended sediment 悬浮沉积物94. atmospherical fallout 大气沉降95. laminar flow 层流96. turbulent flow 紊流97. riffle; pool 浅滩；深槽98. channel roughness 河道粗糙度99. sandbar 沙坝100. thalweg 中泓线101. estuary 河口102. lagoon 泻湖103. salinity 盐度104. coastline 海岸线105. dune 沙丘106. suspension; saltation; creep 悬移；跃移；蠕移107. dust storm 尘暴108. windward; leeward 迎风；背风109. prevailing wind 盛行风110. deflation hollow 风蚀凹地111. aridity 干燥度112. tropic of cancer 北回归线113. tropic of capricorn 南回归线114. gobi 戈壁115. continentality 大陆度116. cold ocean current 寒流117. plateau 高原118. alluvial fan 冲积扇119. pediplanation 山麓夷平作用120. deflation 风蚀121. moraine 冰碛122. glacial；interglacial 冰期；间冰期123. Recent 全新世124. Quaternary Era 第四纪125. periglacial period 冰缘期126. nivation 冰蚀127. earth’ orbit 地球轨道128. plucking 挖蚀129. abrasion 磨蚀130. pyramidal peak 角峰131. arete 刃脊132. cirque 冰斗133. horn 角峰134. U-shaped valley (trough) U型谷135. fluvioglacial deposit 冰水沉积136. drumlin 鼓丘137. terminal moraine 终碛138. outwash plain 冰水沉积平原139. kettle hole 锅穴140. wavelength 波长141. crest；trough 波峰；波谷142. wave period 周期143. wave frequency 波频144. wave height 波高145. wave refraction 波浪折射146. tidal range 潮差147. stack 海蚀柱148. arch 海蚀拱桥149. headland 海岬150. troposphere (pause); strato-; meso-; thermo- 对流层（顶）、平流、中间、热成151. pressure-gradient force 气压梯度力152. isobar 等压线153. sub-tropical anticyclone 副热带高压154. cirrus 卷云155. cumulus 积云156. stratus 层云157. cumulonimbus 积雨云158. convection rain 对流雨159. thunderstorm 雷雨160. depression 低气压161. frontal rain 锋面雨162. orographic rain 地形雨163. equatorial trough 赤道低压槽164. front 锋165. temperature inversion 逆温166. soil texture 土壤质地167. loam 壤土168. soil structure 土壤结构169. soil moisture 土壤水分170. field capacity 田间持水量171. cation exchange capacity 阳离子交换量172. podzol 灰化土173. brown earth 褐土174. sandstone 砂岩175. gley 潜育土176. azonal soil 非地带性土壤177. soil horizon 土层178. humification 腐殖化作用179. mineralisation 矿化作用180. eluviation 淋溶作用181. calcification 钙化作用182. salinisation 盐化作用183. gleying 潜育化作用184. illuviation 淀积作用185. savanna 热带稀树草原（萨王纳）186. saline soil 盐土187. biogeography 生物地理学188. biotic ; abiotic element 生物;非生物成分189. autotroph; heterotroph 自养生物；异养生物190. producer; consumer 生产者；消费者191. photosynthesis 光合作用192. herbivore 食草动物193. carnivore 食肉动物194. decomposer 分解者195. trophic pyramid 营养金字塔196. food web 食物网197. primary productivity 初级生产力198. gross productivity 总生产力199. net productivity 净生产力200. continental shelf 大陆架201. succession（prisere）演替202. climax community 顶级群落203. primary (secondary) succession 初级和次级演替English for Geography地理专业英语Lesson 1. Longitude and latitude ...........................经度和纬度P1 (1)Lesson 2. Rotation and revolution of the earth...地球的自转和公转P6 (2)Lesson 4. The major classes of landforms...............主要地形类型P13 (6)Lesson 5 Delta plains ..........................................三角洲平原P16 (8)Lesson 6 Limestone caverns and karst landscapes石灰岩洞和喀斯特景观P21 (8)Lesson 7 Layers of the Earth .................................地球圈层P31 (8)Lesson 8 The rock cycle ..........................................岩石循环P43 (9)Lesson 9 Soil pedogenesis .......................................成土作用p48 (10)Lesson 10 Global scale circulation of the atmosphere全球大气环流 P62 (11)Lesson 11 The Hydrologic Cycle ..............................水循环P74 (11)Lesson 12 Three Model of Urban Land Use..................三种城市土地利用模式P97 (11)Lesson 13 Air pollution cause and effects...............空气污染原因和影响P168 (12)Lesson 14 Hurricane ...................................................飓风P182 (12)Lesson 1. LONGITUDE AND LATITUDE经度和纬度1、The location of points on the earth’s surface follows a system in which lengthsof arc are measured along meridians and parallels；测定地球表面上点的位置是按照沿着子午线（经线）和纬线测量弧长的方法进行的2、that desired point 欲量算的点3、the longitude of a place is the arc, measured in degrees, of a parallel betweenthat place and the prime meridian 经度的定义4、the longitude of a place is the arc, measured in degrees, of a parallel between that place and the prime meridian 某地的经度系该地与本初子午线之间的纬线的弧的度数5、almost universally 几乎一致6、The prime meridian is almost universally accepted as the meridian that passesthrough the old Royal Observatory at Greenwich人们几乎一致承认以通过格林尼治皇家天文台原址的子午线作为本初子午线7、be referred to as 被称为8、Long. 115。

Profess ional English for Social Work课程导入:社会工作究竟是一门什么样的课程？我们为什么要学习社会工作？学习它有什么用？对社会工作有多少了解？请说出你所知道的社会工作概念。

请说出你所知道的社会工作学者。

请说出你所知道的社会工作著作。

请你说说社会工作和社会学是什么关系。

一个简单的说明:《社会工作：专业英语》是社会工作的基础理论学科，也是社会工作的必修课程。

本课程的教学安排旨在提供基本的概念和理论知识，是进入社会工作领域高阶学习的基础。

Chapter One Social work: IntroductionPart 1、专业知识点学习-句子1、Social work is a profession that focuses particularly on helping people.2、Social work helps people to solve their personal, family and community problems.3、Social work emphasizes human values.4、Social work practice is an art with a scientific and value foundation.5、The family is often regarded as the case in social work.6、Social work has distinctive professional bodies.7、The relationship is the key in the social work process.8、Most social workers are employed in agency settings.9、Traditionally social workers have provided services and therapy for individuals and families.10、The basic functions of social work are intertwined and interdependent.11、Most social workers are on fixed salaries.12 、Fees are utilized for the welfare of the agency.13 、We find that people are still center of the world and its values.14 、As people live together, problems of relationship and interaction emerge.15 、Fifteen-second ads channeled into our homes are common.16 、Use of drugs is on the increase around the world.17 、”computer criminals” are on the scene18 、The school counselor and the social worker share much in common.19 、In one sense, social work is a part of marriage counseling.20 、Social work today is utilized in a variety of settings and agencies.Part 2、专业知识点学习-翻译1、有些人将咨询员的角色与作用和社会工作者的角色与作用混为一谈。

第八章-英译汉（一）英译汉要求考生把一般难度、非专业性题材的英文句子或短文译成汉语，译文通顺，用词基本正确，无重大语法错误。

在试卷结构方面，是一篇长度为120个单词左右的短文，要求翻译全文；或者是一个较长的段落，要求翻译其中带有下划线的5个句子。

满分15分，考试时间为25分钟。

重点考查的翻译技巧主要包括：定语从句的翻译、被动语态的翻译、长句的翻译等。

涉及考生的翻译能力，还涉及考生词汇、语法、句型等方面综合运用语言的能力。

解题思路1.通读一遍文章，了解大概内容，确定内容和体裁，以便知道翻译语言是选择比较正式的还是比较随意的。

2.再次阅读，弄清句子中所有实词和虚词的词汇意义，还要理解全句的整体意义。

（确定代词指代的内容、确定多义词或短语在文中的含义、确定翻译部分是否与全文内容一致。

）3.翻译完成后，要对译文进行检查。

这是做完之后弥补失误的一种好方法。

（在数字、日期、距离、方位以及名称等方面有无错漏；有无漏译的词，有无误译的内容、有无逻辑不通、行文不顺之处，有无标点符号用错之处。

）翻译的技巧概述提高阅读能力，增强自己对英语文章内容的理解力；注意锻炼汉语表达能力。

1.翻译原则忠实原文的同时要符合汉语习惯。

不能太拘泥刻板。

能够直译尽量不意译，不要自己创造没有的单词语义（直译是指译文从形式到内容都忠实原文；意译是指译文在内容上忠实于原文，而形式上则有所变通。

）先了解后表达。

2.技巧运用抽象名词的译法：抽象意义具体化，即把抽象名词转化为具体名词或特指的词。

Few people have written English with more grace than Jim.吉姆写得一手优美的英文，很少有人能出其右。

（抽象名词变形容词）被动语态的译法：1.翻译成汉语的主动句——有时，在动作执行者未说出来的情况下，根据原文意思，译时可以加主语“我们”、“人们”。

Every possible means was done to reduce damage.为了减少损失，我们采取了各种措施。

内燃机专业英语自编讲义部分：1. Engine Classification and Overall MechanicsThe automobile engines can be classified according to: 1. number of cylinders; 2. arrangement of cylinders; 3. arrangement of valves; 4. type of cooling; 5. number of cycles (two or four); 6. type of fuel burned; 7. type of ignition.The engine is the source of power that makes the wheels go around and the car move. The automobile engine is an internal-combustion engine because the fuel (gasoline) is burned inside it. The burning of gasoline inside the engine produces high pressure in the engine combustion chamber. This high pressure forces piston to move, the movement is carried by connecting rods to the engine crankshaft. The crankshaft is thus made to rotate; the rotary motion is carried through the power train to the car wheels so that they rotate and the moves.The engine requires a fuel system to supply it with a mixture of air and fuel. The fuel system does this by pumping liquid gasoline from a tank into the carburetor, a mixing device that mixes the gasoline with air. The mixture is delivered to the engine where it is burned.The engine also needs a cooling system, the combustion of the air-fuel mixture in the engine creates a very high temperature (as high as 2000 to 2700 ℃). The cooling system takes heat away from the engine by circulating a liquid coolant (water mixed with antifreeze) between the engine and a radiator. The coolant gets hot as it goes through the engine. It cools off as it goes through the radiator. Thus, the coolant continually takes heat away from the engine, where it could do damage, and delivers it to the radiator. Air passing through the radiator takes heat away from the radiator.The engine also includes a lubricating system. The purpose of the lubricating system is to supply all moving parts inside the engine with lubricating oil; the oil keeps moving parts from wearing excessively.The engine requires a fourth system, the ignition system. The ignition system provides high-voltage electric sparks that ignite, or set fire to, the charges of air-fuel mixture in the engine combustion chambers.The fifth is starting system and its purpose is to change the electrical current into the mechanical energy to push the crank-shaft around. By means of this, the engine can be started.These five systems are discussed briefly in following sections.Words and Expressionscombustion chamber 燃烧室；ignition. 点燃；power train 动力传动系统；carburetor 化油器；antifreeze 防冻的；coolant 冷却剂（液态）；crankshaft 曲轴2. Four-stage-engine OperationThe action taking place in the engine cylinder can be divided into four stages, or strokes. “Stroke” refers to piston movement; as stroke occurs when the piston moves from one limiting position to the other. The upper limit of piston movement is called TDC （top dead center）. The lower limit of piston movement is called BDC (bottom dead center). A stroke is piston movement from TDC to BDC or from BDC to TDC. In other words, the piston completes a stroke each time it change its direction of motion.Where the entire cycle of events in the cylinder requires four strokes (or two crankshaft revolutions), the engine is called a four-stroke-cycle engine, or a four-cycle engine. The four piston strokes are intake, compression, power, and exhaust.Intake stroke. On the intake stroke, the intake valve has opened, the piston is moving downward, and a mixture of air and vaporized gasoline is entering the cylinder through the valve port. The mixture of air and vaporized gasoline is delivered to the cylinder by the fuel system and carburetor.Compression stroke. After the piston reaches BDC, or the lower limit of its travel, it begins to move upward. As this happens, the intake valve closes. The exhaust valve is also closed, so that the cylinder is sealed. As the piston moves upward (pushed now by the revolving crankshaft and connecting rod), the air-fuel mixture is compressed. By the time the piston reaches TDC, the mixture has been compressed to as little as one-tenth of its original volume, or even less. This compression of the air-fuel mixture increases the pressure in the cylinder. When the air-fuel mixture is compressed, not only does the pressure in the cylinder go up, but the temperature of the mixture also increases.Power stroke. As the piston reaches TDC on the compression stroke, an electric spark is produced at the spark plug. The ignition system delivers a high-voltage surge of electricity to the spark plug to produce the spark. The spark ignites, or sets fire to, the air-fuel mixture. It now begins to burn very rapidly, and the cylinder pressure increases to as much as 3-5 MPa or even more. This terrific push against the piston forces it downward, and a power impulse is transmitted through the connecting rod to the crankpin on the crankshaft. The crankshaft is rotated as the piston is pushed down by the pressure above it.Exhaust stroke. As the piston reaches BDC again, the exhaust valve opens. Now, as the piston moves up on the exhaust stroke, it forces the burned gases out of thecylinder through the exhaust-valve port. Then, when the piston reaches TDC, the exhaust valve closes and the intake valve opens. Now, a fresh charge of air-fuel mixture will be drawn into the cylinder as the piston moves down again toward BDC. The above four strokes are continuously repeated.Words and Expressionsstroke 行程，冲程；BDC 上止点；TDC 下止点；surge 冲击，脉动；terrific 了不起的，绝妙的；crankpin 曲柄销，连杆轴颈；intake stroke 吸气冲程；compression stroke 压缩冲程；power stroke 做功冲程；exhaust stroke 排气冲程；fresh charge （发动机）吸入的新鲜混合油气3. Two-stage-engine OperationIn the four-stroke-cycle engine, already discussed in lesson 1、2, the complete cycle of events requires four piston strokes (intake, compression, power, and exhaust). In the two-stroke-cycle, or two-cycle, engine, the intake and compression strokes and power and exhaust strokes are in a sense combined. This permits the engine to produce a power stroke every two piston strokes, or every crankshaft rotation.In the two-cycle engine, the piston acts as a valve, clearing valve ports in the cylinder wall as it nears BDC.A fresh air-fuel charge enters through the intake port, and the burned gases exit through the exhaust port. The complete cycle of operation is as follows: As the piston nears TDC, ignition takes place. The high combustion pressures drive the piston down, and the thrust through the connecting rod turns the crankshaft. As the piston nears BDC，it passes the intake and exhaust ports in the cylinder wall. Burned gases, still under some pressure, begin to stream out through the exhaust port. At the same time, the intake port, now cleared by the piston, begins to deliver air-fuel mixture, under pressure, to the cylinder. The top of the piston is shaped to give the incoming mixture an upward movement. This helps to sweep the burned gases ahead and out through the exhaust port.After the piston has passed through BDC and stars up again, it passes both ports, thus sealing them off. Now the fresh air-fuel charge above the piston is compressed and ignited. The same series of events takes place again and continue as long as the engine runs.We mentioned that the air-fuel mixture is delivered to the cylinder under pressure. In most engines, this pressure is put on the mixture in the crankcase. The crankcase is sealed except for a leaf, or reed, valve at the bottom. The reed valve is a flexible, flat metal plate that rests snugly against the floor of the crankcase. There are holes under the reed valve that connect to the engine carburetor. When the piston is moving up, a partial vacuum is produced in the sealed crankcase. Atmospheric pressure lifts the reed valve off the holes, and air-fuel mixture enters the crankcase. After the piston passes TDC and starts down again, pressure begins to build up in the crankcase. This pressure closes the reed valve so that further downward movement of the piston compresses the tapped air-fuel mixture in the crankcase. The pressure which is built up on the air-fuel mixture then causes it to flow up through the intake port into the engine cylinder when the piston moves down far enough to clear the intake port.The two-stroke engine is not only very simple but gives nearly twice the powerof a four stroke engine from a cylinder of given size, but it is wasteful of gasoline, as some mixture inevitably finds its way into the exhaust system on the combines intake/exhaust stroke, and there are always some combustion products left in the cylinder which reduce the rapid burning of the fuel. This kind of engine is always used in motorcycles.Words and Expressionssweep 扫气；connecting rod 连杆；crankcase 曲轴箱；seal off 密封；leaf （reed）valve 片簧阀；air-fuel charge 可燃混合油气4. Diesel Engine Operating FeaturesWe all know that diesel engines, in principle, work in the same way as gasoline engines do. Both kinds of engines are internal-combustion engines, but each of them has its characteristic features. As their names suggest this type of engines burn their fuel inside the working parts of the engines. “Internal” means “inside”, “combustion”means “catching fire or burning”. In any internal combustion engine, burning fuel heats air which consequently expands, and in expanding exists a push to a piston which, in turn, rotates the engine crankshaft through a connecting rod.Now let us compare the diesel engine with the gasoline engine. Firstly, the explosive mixture of the gasoline engine is provided by a carburetor, but in the case of the diesel engine the supply is a ffected by an injection or “jerk” pump which forces a “short” of fuel into each cylinder in turn according to the correct firing sequence. Secondly, the fundamental difference between gasoline and diesel engines is that in the gasoline engine the source of the heat for igniting the charge, namely, an electric spark, is generated outside the engine, and is taken, as it were, into the waiting charge at the required instant. In the diesel engine the source of heat for igniting the charge is created within the engine by compressing pure air to a degree that will initiate combustion and then injecting the fuel at the right time in relation to the movement of the crankshaft. Both classes of engines are of very similar construction. But as the diesel engine is called upon to withstand very much greater stresses due to higher pressures in cylinders, it has to be of more substantial construction, and is thus heavier. In general, the diesel engine may weigh about 9.25 kilograms per kilowatt. The most important advantage of the gasoline engine is its lower weight per kilowatt. The gasoline engine for automobiles weighs about 6.17 kilograms per kilowatt, and gasoline engines for airplanes may weigh as little as 0.77 kilograms per kilowatt. This advantage prevents the diesel engine from replacing the gasoline engine in some automobiles and airplanes.However, the diesel engine is more efficient, because it has higher compression ration. Its ratio may be as high as 16 to 1. Up to 40 percent of the chemical energy of the burning fuel may be changed into mechanical energy. In addition, the diesel engine runs cooler than the gasoline engine. This advantage is especially obvious at lower speeds. Diesel oil is not only cheaper than gasoline, but also safer to store. Words and Expressions：diesel：柴油机；internal-combustion engines：内燃机；jerk pump：脉动史喷油泵；compression ration：压缩比5. Engine Cylinder Block CrankcaseWe have seen how the mixture of air and fuel is delivered by the fuel system to the engine cylinder, where it is compressed, ignited, and burned. We have noted that this combustion produces a high pressure that pushes the piston down so that the crankshaft is rotated. Now let us examine the various parts of the engine in detail.Engine cylinder blockThe cylinder block of liquid-cooled engines forms the basic framework of the engine. Other parts are attached to the cylinder block or are assembled in it. The block is cast in one piece from gray iron or iron alloyed with other metals, such as nickel or chromium. Some blocks are cast from aluminum. The block contains not only the cylinders but also the water jackets that surround them. In aluminum blocks, cast-iron or steel cylinder sleeves (also called bore lines) are used. These metals have better wearing qualities than aluminum and can better withstand the wearing effect of the pistons and ring moving up and down in the cylinders. For most engines, cast iron has been found to be a satisfactory cylinder-wall material. However, in some small engines, the cylinder walls are plated with chromium, a very hard metal, to reduce wall wear and lengthen their life.Cylinder HeadThe cylinder head is usually cast in one piece from iron, from iron alloyed with other metals, or from aluminum alloy. Aluminum has the advantage of combining lightness with high heat conductivity. That is, an aluminum head tends to turn cooler, other factors being equal. There are two types of head, L head and I head. Cylinder head contains water jackets for cooling; in the assembled engine, these water jackets are connected through openings to the cylinder-block water jackets. Spark-plug holes are provided, along with pockets into which the valves can move as they open.GasketsThe joint between the cylinder block and the head must be tight and able to withstand the pressure and heat developed in the combustion chambers. The block and head cannot be machined flat and smooth enough to provide an adequate seal. Thus, gaskets are used. Head gaskets are made of thin sheets of soft metal or asbestos and metal. All cylinder, water, valve, and head-bolt openings are cut out. When the gasket is placed on the block and the head installed, tightening of the head bolts (or nuts) squeezes the soft metal so that the joint is effectively sealed. Gaskets are also used to seal joints between other parts, such as between the oil pan, manifolds, orwater pump and the block.Oil PanThe oil pan is usually formed of pressed steel. It usually holds 5 to 10 litres of oil, depending on the engine design. The oil pan and the lower part of the cylinder block together are called the crankcase; they enclose, or encase, the crankshaft. The oil pump in the lubricating system draws oil from the oil pan and sends it to all working parts in the engine. The oil drains off and runs down into the pan. Thus, there is constant circulation of oil between the pan and the working parts of the engine.Words and Expressionscylinder block 气缸体；block crankcase 曲轴箱；framework 结构，车架；gray iron 灰铸铁；water jacket 水套；plate……with 镀金属；cylinder head 气缸盖；gaskets 密封垫；asbestos 石棉；manifold 岐管；oil pan 油盘；pocket 凹槽；bore liner 气缸衬套6. Piston Connecting RodPistonThe piston is essentially a cylindrical plug that moves up and down in the engine cylinder. It is equipped with piston rings to provide a good seal between the cylinder wall and piston. The piston absorbs heat from the gas, and this heat must be carried away if the metal temperature is to be carried away if the metal temperature is to be held within safe limits. The constant reversal of the piston travel sets up inertial forces, which increase both with the weight of the piston and with its speed. For this reason, designers try to keep piston weight low, particularly in high-speed engines. As lower hood lines and over-square engines became popular, the semi-slipper and full-slipper pistons came into use. On these pistons the number piston rings was reduced to three, two compression and one oil-control. One reason for the slipper piston is that, on the short stroke, over-square engine, the piston skirt had to be cut away to make room for the counterweights on the crankshaft. Also, the slipper piston, being shorter and having part of its skirt cut away, is lighter. This reduces the inertial load on the engine bearings and, in addition, makes for a more responsive engine. The lighter the piston, the less the bearing load and the longer the bearings will last. Another way to lighten the piston is to make it of light metal. The idea piston material would be light and strong, conduct heat will, expand only slight when heated, resist wear, and be low in cost. Thus, most automotive-engine pistons today are made of aluminum, which is less than half as heavy as iron. Iron pistons were common in the earlier engines. Aluminum expands more rapidly than iron with increasing temperature, however, and since the cylinder block is of iron, special provisions must be made to maintain proper piston clearance at operating temperatures. To take care of it, the crown is machined on slight taper, the diameter being greatest where the crown meets the skirt and becoming less toward the top.Piston RingsA good seal must be maintained between the piston and cylinder wall to prevent blow-by. “Blow-by” is the name that describes the escape of burned gases from the combustion chamber, past the piston, and into the crankcase. In other words, these gases “blow by” the piston. It is not practical to fit the piston to the cylinder closely enough to prevent blow-by. Thus, piston rings must be used to provide the necessary seal. The rings are installed in grooves in the piston. Actually, there are two types of rings, compression rings and oil-control rings. The compression rings seal in theair-fuel mixture as it is compressed and also the combustion pressures as the mixture burns. The oil-control rings scrape off excessive oil from the cylinder wall and return it to the oil pan.The rings have joints (they are split) so that they can be expanded and slipped over the piston head and into the recessed grooves cut in the piston. Rings for automotive engines usually have butt joints, but in some heavy-duty engines, the joints may be angles, lapped, or of the sealed type.The rings are somewhat larger in diameter than they will be when in the cylinder. Then, when they are installed, they are compresses so that the joints are nearly closed. Compressing the rings gives them an initial tension; they press tightly against the cylinder wall.Connecting RodThe connecting rod is attached at one end to a crankpin on the crankshaft and at the other to a piston, through a piston pin or wrist pin. The connecting rod must be very strong and rigid and also as light as possible. The connecting rod carries the power thrusts from the piston to the crankpin. At the same time, the rod is in eccentric motion. To minimize vibration and bearing loads, the rod must be light in weight. To maintain good engine balance, connecting rods and caps are carefully matched in sets for engines. All rods in an engine must be of equal weight; if they are not, noticeable vibration may result. In original assembly, rods and caps are individually matched to each other and usually carry identifying numbers so they will not be mixed if the engine is disassembled for service. They must not be mixed during any service job, since this could result in poor bearing fit and bearing failure.Words and Expressionscounterweight 平衡重；groove 凹槽；recess 凹口；lap 搭接；eccentric 偏心的；lower hood lines 低发动机罩；over-square engine 短行程发动机；semi-slipper piston 半裙式活塞；full-slipper piston 全裙式活塞；match in set 配套；blow-by 漏气；initial tension 初张力；poor bearing fit 轴承不配套；bearing failing 轴承故障。

材料科学与工程专业英语Materials Science and EngineeringUnit1Materials Science and EngineeringMaterials are properly more deep-seated in our culture than most of us realize. 材料可能比我们大部分人所意识到的更加深入地存在于我们的文化当中。

Transportation, housing, clothing, communication, recreation and food production－virtually every segment of our lives is influenced to one degree or another by materials.运输、住房、衣饰、通讯、娱乐，还有食品生产——实际上我们日常生活的每个部分都或多或少地受到材料的影响。

Historically, the development and advancement of societies have been int imately tied to the members’ abilities to produce and manipulate materials to fill their needs. 从历史上看，社会的发展和进步已经与社会成员生产和利用材料来满足自身需求的能力紧密地联系在一起。

In fact, early civilizations have been designated by the level of their materials development.事实上，早期文明是以当时材料的发展水平来命名的。

（也就是石器时代，青铜器时代）The earliest humans has access to only a very limited number of materials, those that occur naturally stone, wood, clay, skins, and so on. 最早的人类只能利用非常有限数量的材料，象那些自然界的石头，木头，黏土和毛皮等等。