科技英語部分課后練習答案

1、A multibillion-dollar craft called the Crew Exploration Vehicle (CEV).David Gump and Gary Hudson; an entrepreneur with fresh ideas.Innovative technology.Viability of a new method for air-launching spacecraft .Win money from NASA and private investors. 1-5 CBAAC 6-10 BDCAA3.3.試圖利用計算機來復制人腦活動方式的數(shù)學家試圖利用

2、計算機來復制人腦活動方式的數(shù)學家們發(fā)現(xiàn)，即使運用最先進的電子設備，他們也要們發(fā)現(xiàn)，即使運用最先進的電子設備，他們也要建造一臺重建造一臺重1 1萬公斤的計算機才行。萬公斤的計算機才行。4.4.結果表明，在相當長的時間內，全球平均氣溫結果表明，在相當長的時間內，全球平均氣溫都是相當穩(wěn)定的，可極小的溫度變化卻意味著環(huán)都是相當穩(wěn)定的，可極小的溫度變化卻意味著環(huán)境的巨大改變。境的巨大改變。5.5.但是，最近發(fā)表在科學雜志的一對研究報告并但是，最近發(fā)表在科學雜志的一對研究報告并沒有驗證生物燃料的這種作用。并且，事實上，沒有驗證生物燃料的這種作用。并且，事實上，相對于要被取而代之的化石燃料來說，生物燃料相對

3、于要被取而代之的化石燃料來說，生物燃料對氣候產生的危害是有過之而無不及。對氣候產生的危害是有過之而無不及。6.6.盡管備受關注的是研發(fā)金屬，陶瓷，聚合物與盡管備受關注的是研發(fā)金屬，陶瓷，聚合物與復合材料材質的改善，復合材料材質的改善， 但有能力生產，制造可但有能力生產，制造可以滿足特定需求的材料現(xiàn)在也在漸漸變成現(xiàn)實。以滿足特定需求的材料現(xiàn)在也在漸漸變成現(xiàn)實。7.7.信息高速公路是一種電子通訊網(wǎng)絡，這一網(wǎng)絡信息高速公路是一種電子通訊網(wǎng)絡，這一網(wǎng)絡把所有的人互相聯(lián)系起來，并可提供任意一種人把所有的人互相聯(lián)系起來，并可提供任意一種人們想得到的電子通訊方式。們想得到的電子通訊方式。8.8.如果把管子裝

4、成這個樣子，使最熱的水上升，如果把管子裝成這個樣子，使最熱的水上升，而最冷的水流下來后返回鍋爐里去，那么，鍋爐而最冷的水流下來后返回鍋爐里去，那么，鍋爐中的熱水系統(tǒng)不用水泵就能循環(huán)，道理就在于此。中的熱水系統(tǒng)不用水泵就能循環(huán)，道理就在于此。9.9.多種因素促使人們更加關注多種因素促使人們更加關注( (垃圾的處理垃圾的處理)/)/這這種興趣的產生有很多因素，包括對垃圾越來越種興趣的產生有很多因素，包括對垃圾越來越多，垃圾填埋場地越來越少，焚燒垃圾造成的多，垃圾填埋場地越來越少，焚燒垃圾造成的空氣污染越來越嚴重的擔心；及對環(huán)境保護的空氣污染越來越嚴重的擔心；及對環(huán)境保護的必要性已形成的共識等。必要

5、性已形成的共識等。10.10.無論是用作轎車和公汽的能源，還是發(fā)電作無論是用作轎車和公汽的能源，還是發(fā)電作其他的什么用途，燃料電池都是無需燃燒就可其他的什么用途，燃料電池都是無需燃燒就可將氫轉化成電能。將氫轉化成電能。11.11.每個化學元素在周期表中都有一定的原子數(shù)每個化學元素在周期表中都有一定的原子數(shù)和位置，可以據(jù)此來推測其特性：如何同別的元和位置，可以據(jù)此來推測其特性：如何同別的元素相互作用，能形成什么樣的化合物，以及它的素相互作用，能形成什么樣的化合物，以及它的物理屬性。物理屬性。12.12.固體加熱到足夠溫度時，它所含的電子就會有固體加熱到足夠溫度時，它所含的電子就會有一部分離開固體

6、表面而飛到周圍的空間中去；這一部分離開固體表面而飛到周圍的空間中去；這種現(xiàn)象稱為熱電子放射；通常，電子管就利用這種現(xiàn)象稱為熱電子放射；通常，電子管就利用這種現(xiàn)象產生自由電子。種現(xiàn)象產生自由電子。The current calibration methods of the projectile-velocity measurement system are introduced, and the problem and the unreasonableness of these methods are analyzed. Based on the principle of the mathema

7、tical statistics, the calibration method is investigated that measures the projectile-velocity at the same time by the multi-group zone-block device is unbiased, uniform and efficient and uses the average of the measured value as the true value of the projectile-velocity at the point. The method adv

8、antages are analyzed too. The calibration system of the projectile-velocity measurement system based on the laser screen targets is established. The experiment and the data process prove that the method is not only feasible, but also provides an effective calibration method for quantificationally (定

9、量定量) giving the uncertainty of measuring the projectile-velocity quantitatively.a. Aimed at the system consisting of square plansifter and flexible suspender attached to square plansifter，the rigid-flexible coupling dynamic modeling and the finite element simulation are employed to study it. The non

10、linear dynamic equation of square plansifter is established based on the Lagrange equation, and the kinematic circle law is derived from stabilization condition. By using MSC.Patran/Nastran, the finite element model of square plansifter is created and the transient response analysis is applied. The

11、theoretic model and the results of finite element simulation are verified by experimental date. The dynamic model and finite element simulation method presented in this paper possess an important reference value and guidance to intensity checkout and structure optimization of square plansifter.b. In

12、 order to obtain the accurate and efficient simulation algorithm for describing the rotation of the fuze ball rotor, two kinds of the fuze ball rotor are numerically simulated with the mathematical model of quaternion as examples. Runge-Kutta method and Gear method are adopted.The results show that

13、comparing with the nonlinear mathematical model of Euler angles ,the model of quaternion of fuze ball rotor is able to avoid the singularity when the nutation angle approaches 0or 180.The arithmetical solution can be obtained by Runge-Kutta method instead of using the Gear method which is complicate

14、d and more time-consumed for calculation.I. 1-7: F T F T T F FII. 1. That branch of scientific analysis which deals with motions, time and forces is called mechanics.2. Statics deals with the analysis of stationary systems, i.e., those in which time is not a factor. 3. Dynamics deals with systems wh

15、ich change with time.4. Geometry and mechanics. By the separation of Geometry from Mechanics, the determination of the motion from dynamical principles will be made much easier than if the two parts were undertaken conjointly. These two aspects of dynamics were later recognized as Kinematics and kin

16、etics, and deal with motion and the forces producing it, respectively.5. Kinematics is the study of motion. More particularly, kinematics is the study of position, displacement, rotation, speed, velocity, and acceleration. The study, say, of planetary or orbital motion is also a problem in kinematic

17、s.6. Euler based his separation of dynamics into kinematics and kinetics on the assumption that they should deal with rigid bodies. It is this very important assumption that allows the two to be treated separately.7. Although all real machine parts are flexible to some degree, machines are usually d

18、esigned from relatively rigid materials, keeping part deflections to a minimum. Therefore, it is common practice to assume that deflections are negligible and parts are rigid.III. a-d；b-a; c-j; d-b; e-c;f-I; g-f; h-g; i-h; j-e IV. convert motion familiar various Furthermore suitable combine techniqu

19、eI. 1.In dimensioning a drawing, nominal size is the numbers placed in the dimension lines that represent dimensions that are only approximate and do not represent any degrees of accuracy unless so stated by the designer. 2.In engineering practice, a permissible deviation from the nominal size is te

20、rmed as tolerance.3.If the dimension of the shaft is lower than the dimension of the hole, then there will be clearance. Such a fit is termed clearance fit. 4.If the dimension of the shaft is more than that of the hole, then it is termed interference fit.5.Dimensions given close tolerances means tha

21、t the part must fit properly with some other parts.I. 6.Allowance is the minimum clearance space intended between mating parts and represents the condition of the tightest permissible fit.7.Unilateral tolerance means that any variation is made in only one direction from the nominal or basic dimensio

22、n.8. The tolerance would be bilateral if it varies both over and under the nominal dimension.II. Measurement; straight; volumes; irregular ; foundation; necessary; instruments; accuracyquantitysymbolUnitAbbreviationLengthlmetermMassmkilogramkgTimetsecondsecEnergyejouleJForceFNewtonNPowerPWattWCharge

23、QcoulombCCurrentI or iampereAVoltageV or vvoltVResistanceRohmCapacitanceCfaradFInductanceLhenryHTemperatureTKelvinKIV.1. 緊公差的尺寸表示該零件必須與其他零件恰緊公差的尺寸表示該零件必須與其他零件恰當配合。兩者所示公差必須要與設計允差、制當配合。兩者所示公差必須要與設計允差、制造工藝的能力以及獲取最大利潤的最小生產與造工藝的能力以及獲取最大利潤的最小生產與轉配成本一致。轉配成本一致。2. 容差有時與公差相混淆，兩者的意義是完全容差有時與公差相混淆，兩者的意義是完全不同的。容差

24、是在兩配合零件間允許的最小間不同的。容差是在兩配合零件間允許的最小間隙，表示配合允許的最緊的狀態(tài)。隙，表示配合允許的最緊的狀態(tài)。3. 單向公差允許容差與配合類型不變化的情況單向公差允許容差與配合類型不變化的情況下改變公差。而對雙向公差來說，如果不改變下改變公差。而對雙向公差來說，如果不改變兩個配合零件中的一個或兩個的公稱尺寸，改兩個配合零件中的一個或兩個的公稱尺寸，改變公差是不可能的。變公差是不可能的。I. 1.Standard machine tools are usually grouped in six basic classes: lathes, drilling machines,

25、shapers, planers, milling machines, and grinding machines.2.Grinding. Grinding is one of the most accurate of all the basic machining methods. A grinder differs from other machines in that it uses a tool made of emery, carborundum(金剛砂), or similar materials. The wheel, made up of many tiny cutting p

26、oints, cuts with the entire surface area that comes in contact with the material being ground. Grinders cut with a grinding action, removing material in the form of tiny particles.II. 車床lathe/turning machine 鉆床driller/drilling machine 鏜床borer/boring machine磨床grinder/grinding machine 齒輪加工機床gear cutti

27、ng machine螺紋加工機床threading machine銑床miller/milling machine 刨插床planer/shaper拉床broacher/broaching machine電加工機床electric machine切割機床cutting machineIII.size； blueprints； removing; figures; indicate; modification; belongs; stands; improvedIV.1. 每一種機床都根據(jù)這樣的原理來工作：對刀每一種機床都根據(jù)這樣的原理來工作：對刀具或者工件施以運動并使兩者相接觸。然而，具或者工

28、件施以運動并使兩者相接觸。然而，每種機床在所采用的運動方式或所應用的方法每種機床在所采用的運動方式或所應用的方法上，又各不相同。上，又各不相同。2. 旋轉的刀具垂直于工件的表面進行連續(xù)的切旋轉的刀具垂直于工件的表面進行連續(xù)的切削。多刃刀具旋轉與直線進給兩種運動合成后，削。多刃刀具旋轉與直線進給兩種運動合成后，就可以在工件上加工出滿足要求的孔。就可以在工件上加工出滿足要求的孔。3. 砂輪的表面是由許多極小的微刃（砂粒）組砂輪的表面是由許多極小的微刃（砂粒）組成，操作者通過移動工件與砂輪表面接觸。成，操作者通過移動工件與砂輪表面接觸。 I.T T F F T T F F F TII.數(shù)控，數(shù)字控制numerical control計算機輔助工程computer-aided engineering管理信息系統(tǒng) management information systems圖形終端graphic termi