1、1矮米特博士2001年畢業于哈佛大學Dr. Emmet graduated from Harvard University in 20012李教授1988年在西安理工大學獲得機械工程博士學位Professor Li earned his Ph.D. degree in mechanical engineering from the Xian University of Technology in 1988.3現在我們轉向討論一下局與網Now we shall turn to the discussion of local area networks.4 BAINBRIDGE質譜儀是與光譜儀一樣

2、重要的儀器The Bainbridge mass spectrometer is as important an instrument as the optical spectrometer.5做這個實驗需要多長時間How long a time 或How much time is required to this experiment?6壓力的增加總會引起體積的減少。An increase in pressure always causes a decrease in volume7圖2-5畫出了式2-2所表示的情況。Fig. (2-5) shows what is expressed by

3、 Eq. (2-2).8電感的單位是亨利The unit of inductance is the henry.9該電路由一個電池。一個電感和一個電容器組成This circuit consists of a battery, an inductor and a capacitor.10試計算在A B C三點處的電場。Compute the electric fields at points a, b, and c.11這顆衛星用于美國與英國 法國 意大利之間的通信This satellite is used for communications between the United Stat

4、es and Great Britain, France and Italy.12我們假設該天線是垂直的 其損耗為零We assume that the antenna is vertical and that its loss is zero.13第6 7 8章論述傳輸線Chapters 6, 7, and 8 deal with transmission lines.14其誤差為千億分之六Its error is six parts in 1012.15這臺計算機所儲存的信息比那臺多2倍。This computer stores four times more information th

5、an that one (does).16不久的將來對這種設備的需求量為現在的20倍The demand for this kind of equipment in the near future will be 20 times what it is.17這個元件上的電壓為零點幾伏特The voltage across this component is a few tenths of a volt.18現在其內部的壓力減少了15倍Now its internal pressure is one sixteenth what it was.19這種新型計算機與普通計算機相比有許多優勢This

6、 new type of computer has many advantages over the general type20解這個微分方程把未知量求出來并不困難It is not difficult to solve this differential equation for the unknown quantity.21在這新的五章中，第一章論述負反饋的基本原理Of these five new chapters, the first one deals with the basic principles of negative feedback.22這時 電流與電壓相位相差90度A

7、t this point/time, current differs in phase from voltage by 90o.23通過分析該儀器的參數 我們就能夠了解它的性能By analyzing By the analysis of the parameters of the instrument, we can understand its performance.24我們要求它在這一距離上的平均速度We will find out its average velocity over this distance.25電子學這門科學在現今世界太重要了The science of elec

8、tronics is too important in the world today. 26他們極為困難地解出了這道題They solved this problem with great difficulty.27若X1 則方程成立 For x1, there is no solution to this equation。28在把這些數值代入該方程后 我們得到了下面的表達式Upon On substituting substitution of these values into in theequation, we obtained the following expression.2

9、9這個電路的工作情況類似于圖1-10的電路This circuit is similar in operation to that of Fig. 1-10.30這臺計算機的性能很好This computer is very good in performance.31這些波只向一個方向傳播These waves travel only in one direction.32該力垂直于桌面作用The force acts perpendicular to the surface of the table.33這里的三個系數有待于確定The three coefficients here rem

10、ains to be determined.34下面兩個式子在后面幾章將會經常用到 The two equations below will be often (frequently) used in later chapters/in the chapters which follow.35這里我們使用相距10厘米的兩個金屬球Here we use two metal balls 10 cm apart.326輸出保持不變The output remains/stays constant/unchanged/fixed/unaltered/the same.37現在的教科書均討論了這個問題A

11、ll the textbooks available discuss this problem.38計算機由于運算 速度快而得到了廣泛的應用Accurate in operation and high in speed, computers have found wide applications.39這個題的答案看起來是正確的The answer to this problem looks correct.40我們將使用一段相距距離為 的兩根平行導線Two parallel wires a distance (of)apart carry the current i.41現在的問題是如何測量

12、元件上的電壓The problem now is how to measure the voltage across this component.42這些數據將被傳送到2千米外的計算機中心These data will be sent to the computing center 2 kilometers away.43在對上面的那個方程整理后 我們得到了下面的表達式Urearranging the equation above, we have get, obtain the following expressionpon.44這些電荷能與存在的其他電荷相互作用These charges

13、 can interact with other charges present.45力可以沒有接觸而被傳遞 這與普通的觀念相反Forces can be transmitted without contact, contrary to the common belief.46這個系數的典型值為0。35This coefficient is typically 0.35.47這個方程我們應該可以用以下兩種方法的任何一種來解This equation can be solved in either of the following two ways/the two ways which foll

14、ow.48這個棒球不久會停下來 是因為它與地面相互作用的緣故This baseball will soon come to rest because of its interaction with the ground.49我們把這個系數選為1是正確的Our choice of this coefficient as 1 is correct.50從把它定義為力與長度之比 我們可以看出K具有與功相同的單位Frof a force to a length, we can see that k has the same unit as work om its definition as the r

15、atio 51我們對該機器的分析很有意義Our choice of this coefficient as 1 is correct.52這有助于把他們用在電路分析中This facilitates their use in circuit analysis.53這輛警車裝備了像火柴盒那樣大的接收機This police car is equipped with a receiver the size of a matchbox. 54人們使用一根絲線的百分之一那樣粗細的導線來連接這些部件Wires one hundredth the diameter of a silk thread are

16、 used to connect these components.55我們必須對這些設備進行水冷卻We must water cool these equipments/devices.56在過去 電話是靠接線員來連接的In the past, telephone calls were operator connected.57交流電可以被轉換成直流電 這一過程被稱為整流AC can be changed/turned/converted/transformed/translated into/to DC, a process called/known as/referred to as r

17、ectification.58磁鐵能夠吸引鐵制材料，這是大家熟悉的現象A magnet attracts iron materials, a familiar phenomenon.59計算機能夠處理信息 而這一過程以前只能在我們的頭腦里完成Computers are capable of processing information, a process that previously could be accomplished only inside our heads.60萬里表是測量電流 電壓 電阻的儀表 它廣泛應用在電氣工程中An instrument for measuring c

18、urrent, voltage, and resistance, the multimeter is widely used in electrical engineering.61第1.1和1.2節將討論其他幾個問題Secs. 1.1 and 1.2 will discuss several other problems.62習題列在第1到5頁上Problems are listed/given on pp. 1-5.63在上面的幾個式子中 所有的H都是混合參數In the equations above, all hs are the hybrid parameters64標準磅的質量等于

19、 千克The mass of the standard pound is equal to 0. kilograms.65式5-1中的所有A和B都是與阻抗R有關All as and bs in Eq. (5-1) are related to the impedance Ro66我們必須把溫度對半導體的影響考慮進去We must take the effect of temperature on upon semiconductors intoaccount.67在這個情況下 輸出隨輸入的變化是很小的In this case, the variation of output with inpu

20、t is very small.68這一曲線表示出了距離對于速度的依從關系This curve shows the dependence of distance on/upon speed. 69人們將會注意到 這個像是個實像This image, it will be noticed, is a real image.70我們希望 這個技術問題不久就會解決的This technical problem, we hope, will be solved soon.71 2近似為1000 這一點我們認為在學習數字電子學中是很有用的210 is approximately 1000, a fact

21、 that we think is very useful in the study of digital electronics.72這里應該使用一下比如說100歐姆的電阻器A resistor of say 100 ohms should be used here.73那些教科書均沒有提到著一點None of those textbooks have/has mentioned this point.74這些X值并非都能滿意該方程All of these x values cannot satisfy the equation.75那兩個條件在此均沒有得到滿足Neither of the

22、two conditions is satisfied here.76在前一章我們討論了能量In the preceding/previous chapter, we discussed all kinds of force.77本文討論了設計飛機的一種新方法This paper describes a new method for designing aircraft.78到上個世紀末 該公司已制造了五千部雷達By the end of the last century, the company had manufactured 5 000radars.79自從2008年以來 這個研究所一直

23、在開發一種特殊的機器人Since 2008, this research institute has been developing a special kind of robot80在1 2節介紹了力的概念In Section 1-2, the concept of force was introduced.81早在20世紀40年代 人們發現半導體是很有用的As early as the 1940s, it was found that semiconductors are very useful. 82這一結果也能夠用另一種方法來獲得This result can also be arri

24、ved at in another way.83當時人們沒有使用那一現象At that time no use was made of this phenomenon/, thisphenomenon was made no use of.84這一點將在下一章討論This point will be dealt with in the next section.85這臺計算機的性能比那臺好多了 This computer works much better than that one (does)/This computer is much better in performance than

25、 that one 86這臺計算機所需的元件數比那臺多的多This computer requires many more components that that one 87月亮離地球的距離遠達24萬英里The distance of the moon from the earth is as great as 240 000 miles.88電阻越大 電容器達到其最大電壓所需時間越長The greater the resistance, the longer time it takes for the capacitor to reach its maximum voltage89小達0

26、.1A的電流不能產生足夠的熱The current as small as 0.1 A cannot produce enough heat.90借助于計算機設計這種飛機只需要幾個月的時間It will take a few months to design this kind of aircraft with the help of a computer.91證明這個表達式成立就留作讀者的一個習題It is left as a problem to for the reader to show that this expression holds.92要執行的程序儲存在這一單元中The pr

27、ogram to be executed is stored in this unit.93這山谷用作為建壩的基礎上This valley acts as the foundation on which to build the dam.94這實驗中有許多儀表供學生選擇In this laboratory there are many kinds of instrument for students to choose from.95設t等于零Let t0 equal/be equal to zero.96目標離得越遠 回波返回所需的時間越長The farther away the targe

28、t (is), the longer time it takes for the echo to return.97為使該級數收斂 X必須小于1For the series to converge, x must be less than 1.98我們發現這個概念很難理解We find this concept very difficult to understand.99這個方法使得檢測目標容易得多This method makes it much easier to detect targets.100這個因素會影響計算機存儲信息的能力This factor will affect the

29、 ability of a computer to store information.101我們得求出使r為多大時才能使該級數收斂We have to find out how large to make r so as for the series to converge.102這是畫畫所用的筆This is a pen to draw pictures with.103彈性是物體形變后恢復原形的趨勢Elasticity is the tendency of a body to return to its original condition after being deformed.10

30、4普通物質被說成是電中性的Ordinary matter is said to be electrically neutral.105這一性質使得金屬能夠被作成任何的形狀This property makes it possible for metals to be made into any shape.106這張桌子不適宜學生做實驗This table is unfit for a student to do experiments on.107現在我們考慮取什么樣的積分路徑Now we consider what path of integration to take.108該放大器放大

31、接收到的信號The amplifier amplifies the received signals.109運動的分子具有動能Moving molecules have kinetic energy.110速度等于距離除以時間Speed equals distance divided by time.111電壓等于電流乘以電阻Voltage equals/is equal to current multiplied by resistance.112空氣阻力隨速度的增加而增加The resistance of air increases with the increased/increasin

32、g/an increase in speed.113變壓器是由饒在鐵心上的兩個或多個線圈組成的一種裝置A transformer is a device consisting of two or more coils wound on/round an iron core.114必須求出流過這個元件上的電流It is necessary to find out the current flowing through this component.115這本書 如果使用得當 對讀者是很有幫助的This book, properly used, will be of great help to t

33、he reader.116流過電路的時候 電流會失去一部分能量Flowing through a circuit, the current will lose part of its energy.117若已知時間和速度 我們就能求出距離來Given/Knowing time and speed, we/one can find out distance.118學完這章后 學生們將懂得計算機原理了Having studied this chapter, the student will understand/will have understood the principle of a com

34、puter.119由于光速極大 我們不能用普通的方法來測量它The speed of light being extremely great, we cannot measure it by ordinary methods.120在過去發射了幾顆通信衛星 他們都是高空衛星Several comsats were launched, all of them (being) high-altitude satellites.121因特網被稱為所有網絡之母 它是使用極為廣泛的國際網絡Called “the mother of all networks,” the Internet is a wid

35、ely used international network.121這個力可以分解成兩個分量 一個是水平的一個是垂直的This force can be resolved into two components, one (being) horizontal and the other vertical.122讓我們以原點為圓心作為半徑為r的圓Let us construct/draw a circle with the origin as the center and of radius R.123這個參數應該在E接地的情況下加以測量This parameter should be meas

36、ured with E grounded.124若電路中沒有電阻 電流就會無限增大With no resistance in the circuit, the current will increase indefinitely.125由于考慮到這一點 我們編寫了這本書With this in view, we have written this book.126本文介紹了一種新的設計方法 重點放在其原理上This paper introduces a new design method/technique, with emphasis on its principle.127讓我們來考慮設計

37、一臺計算機Let us consider designing a computer.128我們把這些元件稱為是無源的We refer to these components as being passive.129這涉及到取傅式變換This involves taking the Fourier transform.130對上面的方程整理后 我們得到了以下一個方程組On/Upon rearranging the above equations, we obtain the following set of equations.131在使用這個式子時 把哪一個平面看成1是沒有關系的In usin

38、g this equation, it does not matter which plane is considered as 1.132直到引入了一種完全不同的概念 這個問題才得到了解決The problem was not solved until a completely different method was introduced.133在過了將近一百年之后才由實驗證實了亞原子微粒的存在Nearly 100 years passed before the existence/presence of subatomic particles was confirmed by exper

39、iment/experimentally.134在發明該設備的那年 爆發了第二世界大戰The year this device was invented, World War II broke out.135雖然原子很小 它們是由更小的微粒構成的Small as they are, atoms are made up of still smaller particles.136這兩個電阻應該選擇得使該晶體管能正常工作These two resistors should be selected/chosen so that the transistor can operate normally.

40、137該物體處于這樣的狀態以至于它能做功The body is in such a state that it can do work.138電壓是電流和電阻之乘積這一關系適用于一切直流電路The relation that voltage is the product of current and resistance applies to all the dc circuits139磁能夠產生電流這一發現在電學領域中是極為重要的The discovery that magnetism can produce current is extremely important in the fie

41、ld of electricity.140方程式就是兩個代數式相等的一種代數陳述An equation is an algebraic statement that two algebraic expressions are equal.141有證據表明 月球上沒有生命存在There is evidence that no life exists on the moon.142現在出現了這么個問題 該算法是否實用呢？The question now arises whether the algorithm is of practical use.143在這種情況下 不能保證該級數是收斂的In

42、this case there is no guarantee that the series is convergent144人們越來越認識到這些方法是很有用的There is a growing/increasing awareness that these techniques/methods are very useful145當時最顯著的成就之一是人們認識到了光是由電磁波組成的One of/Among the most noteworthy achievements at that time was the realization that light consists of ele

43、ctromagnetic waves.146這是由于導體中存在有許多自由電子引起的This is due to/is caused by/results from the fact that there are many free electrons in conductors.147除了材料的性質應該包括在分析模型之中外 我們還必須把其他因素考慮進去Besides/In addition to the fact that the properties of the material should be included in the analytical model, we must tak

44、e other factors into account.148現在有待于確定該級數何時收斂Now it remains to be determined when the series converges.149從杜巴梅爾定理可清楚地看出 這個極限是存在的It is clear from Dubamels Theorem that this limit exists.150由麥克斯韋假設得知 每當電場發生變化時就產生出磁場It follows from Maxwells hypothesis that whenever there is a change in an electric fie

45、ld, a magnetic field is produced.151在這種情況下磁鐵是否被運動是沒有關系的It does not matter whether the magnet is moved in this case.152溫度確定了熱傳遞將朝哪個方向發生Temperature determines in what direction the transfer of heat will take place.153一切物質均是由微粒構成的 這現在已是一個眾所周知的事實了It is now a well-known fact that all matter consists of t

46、iny particles.154發電機所做的是把機械能轉變成電能What a generator does is (to) change mechanical energy into electrical energy.155這一章所講的內容非常重要What this chapter describes/What is described in this chapter is of great importance.156物質是能夠占有空間的東西Matter is what can occupy space.157在這個實驗中我們所發現的是電現象這一嶄新領域What we have disc

47、overed in this experiment is the entirely new realm of electrical phenomenon.158這個方向與假設方向相反This direction is opposite to what has been assumed.159大小 方向和作用點就是我們所說的一個力的三要素Magnitude, direction, and place of application are what we call the three elements of a force.160這些數構成了所謂的實數系These numbers constitu

48、te what is known as the real number system.161在下面 我們要熟悉一些基本概念In what follows, we shall acquaint ourselves with some basic concepts.162我們用來測量一個電阻上電壓的儀表被稱為電壓表The meter (that/which) we use to measure the voltage across a resistor is called a voltmeter.163計算機是人類所曾擁有過的最有效的助手Computers are the most efficie

49、nt assistants (that) man has ever had.164現在這種病不再是原來那樣的嚴重問題了Now this disease is no longer the serious problem (that) it once was.165雷達可以測出無線電回波返回的時間Radar can measure the time (that) it takes for the radio echo to return.166我們必須計算出該物體被提到的距離We must calculate the distance (that/through which) the body i

50、s lifted.167一個物體運動的方向也是很重要的he direction (that/in which) a body moves is also very important.168這個質點每秒鐘震動的次數被叫做頻率The number of times (that/by which) this particle vibrates per/a second is called/termed/named/known as/spoken of as/referred to as frequency.169我們使這兩個比值相等 由此得到了最簡式We equate these two rati

51、os, from which the simplest formula follows/results.170需要確定Y分量降為0的時間It is necessary to determine the time when/that/at which the y-component has decreased to zero.171其每一點的Y坐標均為0的曲線就是X軸The curve the y-coordinate of each point on which is zero is just the x-axis.172該圓切割實軸的點處于A=W處The point at which the

52、 circle cuts the axis of reals is where = .173重力的意思是地球吸引物體的力The force of gravity means the force with which the earth attracts a body.174電子在其上面產生圖像的顯像管的表明稱為熒光屏The surface of a picture tube upon which the electrons produce the picture is called the screen.175作者要感謝本書所屬的那套叢書的編輯們The author would like to express thanks to the editors of the series of which this book is a part/to which this book belongs.176這是給定的兩個矢量為其邊的一個平行四邊形This is a parallel