科技英语部分课后练习答案

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.试图利用计算机来复制人脑活动方式的数学家试图利用

2、计算机来复制人脑活动方式的数学家们发现，即使运用最先进的电子设备，他们也要们发现，即使运用最先进的电子设备，他们也要建造一台重建造一台重1 1万公斤的计算机才行。万公斤的计算机才行。4.4.结果表明，在相当长的时间内，全球平均气温结果表明，在相当长的时间内，全球平均气温都是相当稳定的，可极小的温度变化却意味着环都是相当稳定的，可极小的温度变化却意味着环境的巨大改变。境的巨大改变。5.5.但是，最近发表在科学杂志的一对研究报告并但是，最近发表在科学杂志的一对研究报告并没有验证生物燃料的这种作用。并且，事实上，没有验证生物燃料的这种作用。并且，事实上，相对于要被取而代之的化石燃料来说，生物燃料相对

3、于要被取而代之的化石燃料来说，生物燃料对气候产生的危害是有过之而无不及。对气候产生的危害是有过之而无不及。6.6.尽管备受关注的是研发金属，陶瓷，聚合物与尽管备受关注的是研发金属，陶瓷，聚合物与复合材料材质的改善，复合材料材质的改善， 但有能力生产，制造可但有能力生产，制造可以满足特定需求的材料现在也在渐渐变成现实。以满足特定需求的材料现在也在渐渐变成现实。7.7.信息高速公路是一种电子通讯网络，这一网络信息高速公路是一种电子通讯网络，这一网络把所有的人互相联系起来，并可提供任意一种人把所有的人互相联系起来，并可提供任意一种人们想得到的电子通讯方式。们想得到的电子通讯方式。8.8.如果把管子装

4、成这个样子，使最热的水上升，如果把管子装成这个样子，使最热的水上升，而最冷的水流下来后返回锅炉里去，那么，锅炉而最冷的水流下来后返回锅炉里去，那么，锅炉中的热水系统不用水泵就能循环，道理就在于此。中的热水系统不用水泵就能循环，道理就在于此。9.9.多种因素促使人们更加关注多种因素促使人们更加关注( (垃圾的处理垃圾的处理)/)/这这种兴趣的产生有很多因素，包括对垃圾越来越种兴趣的产生有很多因素，包括对垃圾越来越多，垃圾填埋场地越来越少，焚烧垃圾造成的多，垃圾填埋场地越来越少，焚烧垃圾造成的空气污染越来越严重的担心；及对环境保护的空气污染越来越严重的担心；及对环境保护的必要性已形成的共识等。必要

5、性已形成的共识等。10.10.无论是用作轿车和公汽的能源，还是发电作无论是用作轿车和公汽的能源，还是发电作其他的什么用途，燃料电池都是无需燃烧就可其他的什么用途，燃料电池都是无需燃烧就可将氢转化成电能。将氢转化成电能。11.11.每个化学元素在周期表中都有一定的原子数每个化学元素在周期表中都有一定的原子数和位置，可以据此来推测其特性：如何同别的元和位置，可以据此来推测其特性：如何同别的元素相互作用，能形成什么样的化合物，以及它的素相互作用，能形成什么样的化合物，以及它的物理属性。物理属性。12.12.固体加热到足够温度时，它所含的电子就会有固体加热到足够温度时，它所含的电子就会有一部分离开固体

6、表面而飞到周围的空间中去；这一部分离开固体表面而飞到周围的空间中去；这种现象称为热电子放射；通常，电子管就利用这种现象称为热电子放射；通常，电子管就利用这种现象产生自由电子。种现象产生自由电子。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. 紧公差的尺寸表示该零件必须与其他零件恰紧公差的尺寸表示该零件必须与其他零件恰当配合。两者所示公差必须要与设计允差、制当配合。两者所示公差必须要与设计允差、制造工艺的能力以及获取最大利润的最小生产与造工艺的能力以及获取最大利润的最小生产与转配成本一致。转配成本一致。2. 容差有时与公差相混淆，两者的意义是完全容差有时与公差相混淆，两者的意义是完全不同的。容差

24、是在两配合零件间允许的最小间不同的。容差是在两配合零件间允许的最小间隙，表示配合允许的最紧的状态。隙，表示配合允许的最紧的状态。3. 单向公差允许容差与配合类型不变化的情况单向公差允许容差与配合类型不变化的情况下改变公差。而对双向公差来说，如果不改变下改变公差。而对双向公差来说，如果不改变两个配合零件中的一个或两个的公称尺寸，改两个配合零件中的一个或两个的公称尺寸，改变公差是不可能的。变公差是不可能的。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(金刚砂), 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. 车床lathe/turning machine 钻床driller/drilling machine 镗床borer/boring machine磨床grinder/grinding machine 齿轮加工机床gear cutti

27、ng machine螺纹加工机床threading machine铣床miller/milling machine 刨插床planer/shaper拉床broacher/broaching machine电加工机床electric machine切割机床cutting machineIII.size； blueprints； removing; figures; indicate; modification; belongs; stands; improvedIV.1. 每一种机床都根据这样的原理来工作：对刀每一种机床都根据这样的原理来工作：对刀具或者工件施以运动并使两者相接触。然而，具或者工

28、件施以运动并使两者相接触。然而，每种机床在所采用的运动方式或所应用的方法每种机床在所采用的运动方式或所应用的方法上，又各不相同。上，又各不相同。2. 旋转的刀具垂直于工件的表面进行连续的切旋转的刀具垂直于工件的表面进行连续的切削。多刃刀具旋转与直线进给两种运动合成后，削。多刃刀具旋转与直线进给两种运动合成后，就可以在工件上加工出满足要求的孔。就可以在工件上加工出满足要求的孔。3. 砂轮的表面是由许多极小的微刃（砂粒）组砂轮的表面是由许多极小的微刃（砂粒）组成，操作者通过移动工件与砂轮表面接触。成，操作者通过移动工件与砂轮表面接触。 I.T T F F T T F F F TII.数控，数字控制numerical control计算机辅助工程computer-aided engineering管理信息系统 management information systems图形终端graphic termi