Chapter 2 Electronics section 2-3 Analog-Digital Conversion 电气工程及其自动化专业英语课件
电气专业英语section 1-6中英
(1-28)
Fig.1-19 voltage-current relation for an inductor in the (a) time domain; (b) frequency domain
Section 6 Sinusoidal AC Circuit Analysis
Fig.1-20 shows the phasor diagram. For the capacitor C, assume the voltage across it is u =Umcos(ωt + ). The current through the capacitor is
For the inductor L, assume the current through it is i I m cos(t ) . The voltage across the inductor is
di u L LI m sin(t ) dt
(1-25)
The voltage is written to
Chapter 1
Fundamentals of Electric Circuits
Section 6 Sinusoidal AC Circuit Analysis and Three-Phase Circuit
Text New Words and Expressions Vocabulary Characteristic II
showing that the current and voltage are 90 out of phase. To be specific, the current leads the voltage by 90. Fig.1-21 shows the voltage-current relations for the capacitor, Fig.1-22 gives the phasor diagram.
【Verilog硬件描述】Verilog HDL-chapter2-3
Microelectronic center
11
Top-Down and Bottom-Up
2.2 Design methodology
Microelectronic center
3
Review
Spec.
Behavior HDL Top_down Flow
High-Level Synthesis
RTL HDL
Area
Synthesis
Timing
Netlist
Power DFT
FPGA Compiler Placement&Routing
▪ For the final physical implementation ▪ VHDL：very high speed integrated circuits
(VHSIC) HDL-IEEE-1076(1987)
▪ Verilog HDL
Microelectronic center
15
2.3 Framework of Verilog HDL
9
2.1 System on Chip
16-State Viterbi
Technology: 0.18 mm (C10N)
Transfer Rate: 850 Mbit/s
Package:
P-TQFP-100
Analog Area: 20 % (relative)
Digital Area: 80 % (relative)
Bottom-up
电气工程及其自动化专业英语第一单元课件
current n.（水，气，电）流；趋势；涌流 1. a flow of electricity through a conductor the current was measured in amperes 2. a steady flow (usually from natural causes) the raft floated downstream on the current 3. dominant course (suggestive of running water) of successive events or ideas the current of history
戴文进主编．专业英语阅读与翻译北京：航空工业出版社， 1998
英文面试：常见的专业英语
数字图像处理 模拟电路 数字电路 信号与系统 机器视觉 模式识别 高等数学 微积分 常微分方程
自我介绍
Good morning,my dear teachers,my dear professors!It is my great honor to take this interview.Thank you very much for giving me the chance! I am open-minded, willing and have broad interests like basketball, reading and especially in engineering such as software programming
circuit n. [电子] 电路，回路；巡回；一圈；环道 vi. 环行 vt. 绕回…环行
an electrical device that provides a path for electrical current to flow
科技英语写作高级教程参考答案
科技英语写作高级教程参考答案科技英语写作高级教程参考答案V、练习参考答案练习1I、1、the(各项均为负。
)2、the; a (功率额定值是电阻器不会引起温度太大的上升而能安全地耗散的最大功率。
)3、an(这是均方根值伏特计。
)4、The; a(该设备的成功设计需要详细地了解性能指标。
)5、the; a; a(在氢原子的布尔模型中，一个电子绕一个质子以半径为R的圆周运转。
)6、the(电阻的单位是欧姆。
)7、an (这是一个h参数。
)8、/; /(图5,1画出了Oersted的实验。
)9、A; a; a(机器是能够传递力来完成某一确定目的的一种设备。
)10、/(水压机将在第14章加以考虑。
)11、the; the [/](我们容易确定参数μ的值。
)12、/; the(根据式(2,1)，我们得到以下的关系式。
)13、the; /(作者工作在位于阿林顿的得克萨斯大学。
)14、an(甚至当积分区间并不是无穷时，能够恰当地显示一个时函数的傅氏变换的仪器是多么重要啊～)II、1. Dr. Emmet graduated from Harvard University in 2001.2. Professor Li earned his Ph.D. degree in mechanical engineeringfrom the Xi’anUniversity of Technology in 1988.3. Now we shall turn to the discussion of local area networks.4. The Bainbridge mass spectrometer is as important aninstrument as the opticalspectrometer.5. How long a time [或How much time] is required to this experiment? The densityof a substance is its mass per unit volume.6. An increase in pressure always causes a decrease in volume.7. Fig. (2-5) shows what is expressed by Eq. (2-2).8. The unit of inductance is the henry.III、1. The UASMA protocol employs a unique frame structure.2. Finally, a broad stepped impedance transformer is designed bythis method.3. Dynamic analysis and evaluation of the security of a proactive secret sharingsystem4. The approach can be applied to the one-dimensional potentialbarrier with anarbitrary profile.5. We propose a numerical method based on Newton’s iterative method.练习2I、1. This circuit consists of a battery, an inductor and a capacitor.2. Compute the electric fields at points a, b, and c.3. This satellite is used for communications between the United States and Great Britain, France and Italy.4. We assume that the antenna is vertical and that its loss iszero.5. Chapters 6, 7, and 8 deal with transmission lines.II、121. Its error is six parts in 10.2. This computer stores four times more information than that one (does).3. The demand for this kind of equipment in the near future will be 20 times what it is.4. The voltage across this component is a few tenths of a volt.5. Now its internal pressure is one sixteenth what it was.III、1. This object is over five times heavier than that one is.2. Unless otherwise stated, it is assumed that silicon transistors are used and that I CBOcan be neglected.3. This circuit has the advantages of simple structure and easy adjustment.4. Figs. 1, 2, and 3 show this process in detail.5. For further information, consult references [3, 5, 9].练习3I、1. This new type of computer has many advantages over the general type.2. It is not difficult to solve this differential equation for the unknown quantity.3. Of these five new chapters, the first one deals with the basic principles of negative feedback.o4. At this point/time, current differs in phase from voltage by 90.5. By analyzing [By the analysis of] the parameters of the instrument, we canunderstand its performance.6. We will find out its average velocity over this distance.7. The science of electronics is too important in the world today.8. They solved this problem with great difficulty.II、1. For x,1, there is no solution to this equation [this equation has no solution].2. Upon [On] substituting [substitution of] these values into [in] theequation, we obtained the following expression..3. This circuit is similar in operation to that of Fig. 1-10.4. This computer is very good in performance.5. These waves travel only in one direction.III、1. This paper presents a new method for the recognition of radar targets.2. The influence of the moving state of the target on the tracking accuracy of the EKF is great.th3. Another comsat was launched on the morning of the 8 of October.4. Voltage is measured in volts.5. They will leave for Beijing to attend an international conference on mobile communication.6. Unless otherwise stated, it is assumed that silicon transistors are used and that I can be neglected. CBO7.练习4I、1. The force acts perpendicular to the surface of the table.2. The three coefficients here remains to be determined.3. The two equations below will be often (frequently) used in later chapters/in thechapters which follow.4. Here we use two metal balls 10 cm apart.5. The output remains/stays constant/unchanged/fixed/unaltered/the same.6. All the textbooks available discuss this problem.7. Accurate in operation and high in speed, computers have found wide applications.8. The answer to this problem looks correct.9. Two parallel wi res a distance (o f)δapart carry the currenti.10. The problem now is how to measure the voltage across this component.11. These data will be sent to the computing center 2 kilometers away.12. Upon rearranging the equation above, we have [get, obtain] the following expression.13. These charges can interact with other charges present.14. Forces can be transmitted without contact, contrary to the common belief.15. This coefficient is typically 0.35.II、1. In this case, the input does not fall; nor [neither] does the output. […; the output does not fall, either.]2. The resistance of a conductor depends not only on the material of which theconductor is made, but also on the size and temperature of the conductor.3. These scientists are very interested in this topic.4. This parameter can hardly be measured.5. In this laboratory, this instrument is more expensive than any other one/ any oneelse.6. The features of this device are small size and light weight.练习5I、1. This equation can be solved in either of the following two ways/the two wayswhich follow.2. This baseball will soon come to rest because of its interaction with the ground.3. Our choice of this coefficient as 1 is correct.4. From its definition as the ratio of a force to a length, we can see that k has thesame unit as work (does).5. Our analysis of the machine is of great significance.6. This facilitates their use in circuit analysis.II、1. This police car is equipped with a receiver the size of a matchbox.2. Wires one hundredth the diameter of a silk thread are used to connect thesecomponents.3. We must water cool these equipments/devices.4. In the past, telephone calls were operator connected.5. AC can be changed/turned/converted/transformed/translated into/to DC, a process called/known as/referred to as rectification.6. A magnet attracts iron materials, a familiar phenomenon.7. Computers are capable of processing information, a process that previouslycould be accomplished only inside our heads.8. An instrument for measuring current, voltage, and resistance, the multimeter iswidely used in electrical engineering.III、1. Secs. 1.1 and 1.2 will discuss several other problems.2. Problems are listed/given on pp. 1-5.3. In the equations above, all h’s a re the hybrid parame ters.4. The mass of the standard pound is equal to 0.4535924277 kilograms.5. All a’s and b’s in Eq. (5-1) are related to the impedance R. o6. We must take the effect of temperature on [upon] semiconductorsintoaccount.7. In this case, the variation of output with input is very small.8. This curve shows the dependence of distance on/upon speed.IV、1. None of them can solve this special type of differential equation.2. They do not know whether this material can stand so largea force or not.3. There are M polygons altogether, each of which has N vertexes.4. These two engineers are busy (in) designing a new kind ofsoftware.5. Iron is almost as good a conductor as aluminum.练习6I、1. This image, it will be noticed, is a real image.2. This technical problem, we hope, will be solved soon.103. 2 is approximately 1000, a fact that we think is very useful in the study of digitalelectronics.4. A resistor of say 100 ohms should be used here.II、1. None of those textbooks have/has mentioned this point.2. All of these x values cannot satisfy the equation.3. Neither of the two conditions is satisfied here.4. In the preceding/previous chapter, we discussed all kinds of force.5. This paper describes a new method for designing aircraft.6. By the end of the last century, the company had manufactured 5 000 radars.7. Since 2008, this research institute has been developing a special kind of robot. III、1. In Section 1-2, the concept of force was introduced.2. As early as the 1940s, it was found that semiconductors are very useful.3. This result can also be arrived at in another way.4. At that time no use was made of this phenomenon/…, thisphenomenon was made no use of.5. This point will be dealt with in the next section.IV、1. This computer works much better than that one(does)/This computer is much betterin performance than that one (is)..2. This computer requires many more components that that one (does).3. The distance of the moon from the earth is as great as 240 000 miles.4. The greater the resistance, the longer time it takes for the capacitor to reach itsmaximum voltage/…, the longer time is required for the capacitor to reach its maximumvoltage.)5. The current as small as 0.1 A cannot produce enough heat.V、1. It is easy for us to determine the weight of the body. 或:We can determine theweight of the body easily.2. The two engineers are busy (in) designing a new type of computer.3. We find this concept very difficult to explain.4. None of these windows can withstand so large a force.5. Work equals [is equal to] force multiplied by/times distance.6. The results obtained agree with the experimental values. [… arein agreement withthe experimental values.]练习7I、1. It will take a few months to design this kind of aircraft withthe help of a computer.2. It is left as a problem to [for] the reader to show that this expression holds.3. The program to be executed is stored in this unit.4. This valley acts as the foundation on which to build the dam.5. In this laboratory there are many kinds of instrument forstudents to choose from.6. Let t equal/be equal to zero. 07. The farther away the target (is), the longer time it takes forthe echo to return.8. For the series to converge, x must be less than 1.9. We find this concept very difficult to understand.10. This method makes it much easier to detect targets.11. This factor will affect the ability of a computer to store information.12. We have to find out how large to make r so as for the series to converge.13. This is a pen to draw pictures with.14. Elasticity is the tendency of a body to return to its original condition after beingdeformed.15. Ordinary matter is said to be electrically neutral.16.This property makes it possible for metals to be made into any shape.17. This table is unfit for a student to do experiments on.18. Now we consider what path of integration to take.II、1. The sine law of the variation of light intensity with the cylinder diameter has beenemphasized.2. Not only do temperature and light affect the conductivity, but the addition ofimpurities to semiconductors also makes it change greatly.3. Various satellites are frequently launched to obtain information about/on space.4. Our semiconductor industry came into being at the end of the 1950s.5. My colleagues and I would like to express our thanks to Professor W. Smith for hisgreat help.练习8I、1. The amplifier amplifies the received signals.2. Moving molecules have kinetic energy.5. Fig. 1 – 3 shows the photo of a freely falling body.3. Speed equals distance divided by time.4. Voltage equals/is equal to current multiplied by resistance.5. The resistance of air increases with the increased/increasing/an increase in speed.6. A transformer is a device consisting of two or more coils wound on/round an iron core.7. It is necessary to find out the current flowing through this component.8. This book, properly used, will be of great help to the reader.9. Flowing through a circuit, the current will lose part of its energy.10. Given/Knowing time and speed, we/one can find out distance.11. Having studied this chapter, the student will understand/will have understood theprinciple of a computer.12. The speed of light being extremely great, we cannot measure it by ordinary methods.13. Several comsats were launched, all of them (being) high-altitude satellites.14. Called “the mother of all networks,” the Internet is a widely used internationalnetwork.15. This force can be resolved into two components, one (being) horizontal and the othervertical.II、1. Let us construct/draw a circle with the origin as the center and of radius R.2. This parameter should be measured with E grounded.3. With no resistance in the circuit,the current will increase indefinitely.4. With this in view, we have written this book.5. This paper introduces a new design method/technique, with emphasis on its principle. III、1. Let us consider designing a computer.2. We refer to these components as being passive.3. This involves taking the Fourier transform.4. On/Upon rearranging the above equations, we obtain the following set ofequations.5. In using this equation, it does not matter which plane is considered as 1.IV、1. Given/Knowing resistance and current, one/we candetermine/calculate voltage.2. The price of this instrument is high.3. A robot is a special kind of electronic device.4. The current starts flowing at the very moment we close thecircuit.5. They have been designing a new type of computer these six months.练习9I、1. The problem was not solved until a completely different method was introduced.2. Nearly 100 years passed before the existence/presence of subatomic particles was confirmed by experiment/experimentally.3. The year this device was invented, World War II broke out.4. Small as they are, atoms are made up of still smaller particles.5. These two resistors should be selected/chosen so that the transistor can operate normally.6. The body is in such a state that it can do work.II、1. The relation that voltage is the product of current andresistance applies to all the dc circuits.2. The discovery that magnetism can produce current is extremely important in the field of electricity.3. An equation is an algebraic statement that two algebraic expressions are equal.4. There is evidence that no life exists on the moon.5. The question now arises whether the algorithm is of practical use.6. In this case there is no guarantee that the series is convergent.7. There is a growing/increasing awareness that thesetechniques/methods are veryuseful.8. One of/Among the most noteworthy achievements at that time wasthe realization thatlight consists of electromagnetic waves.9. This is due to/is caused by/results from the fact that there are many free electrons inconductors.10. Besides/In addition to the fact that the properties of thematerial should be included inthe analytical model, we must take other factors into account.III、1. These features make it difficult for electronic counter-measure systemsto intercept, analyze and jam this kind of signal.2. The existence of and the ability to control these phenomena make those devicespossible.3. The variation of/in the number of the filter’s teeth has a greater effect on the performance of its passband than the variationof/in its dimensions.4. Scalar detection will result in the loss of some phase information.5. Fig. 6 shows the schematic diagram of measuring scatter parameters by the natural parameter transformation method.练习10I、1. Now it remains to be determined when the series converges.2. It is clear from Dubamel’s Theorem that this limit exists.3. It follows from Maxwell’s hypo thesis that whenever there is a change in an electricfield, a magnetic field is produced.4. It does not matter whether the magnet is moved in this case.5. Temperature determines in what direction the transfer of heat will take place.6. It is now a well-known fact that all matter consists of tiny particles.II、1. What a generator does is (to) change mechanical energy into electrical energy.2. What this chapter describes/What is described in this chapter is of great importance.3. Matter is what can occupy space.4. What we have discovered in this experiment is the entirely new realm of electricalphenomenon.5. This direction is opposite to what has been assumed.6. Magnitude, direction, and place of application are what we call the three elements of aforce.7. These numbers constitute what is known as the real number system.8. In what follows, we shall acquaint ourselves with somebasic concepts. III、1. An x-band wave-guide test system is shown in Fig.7. [或:Fig.7 shows …].2. This method lowers the requirement for the hardware of a sample network.3. On the basis of the above analysis of the decomposition of the polynomial, a novelconfiguration results. [或:The above analysis of the decompositionof the polynomial resultsin a novel configuration.]4. Finally, an analysis of packet loss probability is made bycomputer simulation.5. The sparse ratio of the resulting impedance matrix is as high as 40%.练习11I、1. The meter (that/which) we use to measure the voltage across a resistor is called avoltmeter.2. Computers are the most efficient assistants (that) man has ever had.3. Now this disease is no longer the serious problem (that) it once was.4. Radar can measure the time (that) it takes for the radio echo to return.5. We must calculate the distance (that/through which) the body is lifted.6. The direction (that/in which) a body moves is also very important.7. The number of times (that/by which) this particle vibrates per/a second iscalled/termed/named/known as/spoken of as/referred to as frequency.。
06电子专业英语大纲hong
《专业英语》课程教学大纲课程代号：045210学时数：36 理论环节学时数：36 实践环节学时数：0学分：3开课单位：电子电气工程系电子技术教研室一、本课程的性质、地位和作用专业英语课程是针对于电子电气工程系电子专业学生所设置的专业选修课。
本课程具有较强的针对性，要求学生具有一定电子电路技术专业基础知识及大学英语学习的基础，帮助学生复习相应基础知识的同时，进一步巩固、提高英语水平，特别培养学生对一些专业基础性英文材料的阅读能力。
二、本课程的教学目的和要求通过本课程的学习，要求学生能够掌握一定专业英语词汇，了解相应专业性中英文基础文章的理解、翻译，并能够大致正确地理解部分专业类提高性文章的大意三、本课程的相关课程本课程针对性、专业性较强，要求学生具有一定课程学习的基础，主要相关课程包括大学英语、电路基础、电子技术基础、自动控制理论等。
四、课程内容及学时分配Chapter 1 circuit theory fundamentals 12学时Section 1 voltage and currentSection 2 kirchhoff’s laws一、current law二、voltage lawSection 3 two-terminal characterization of elementsSection 4 voltage sourcesSection 5 current sourcesSection 6 resistors and ohm’s lawSection 7 inductors教学的重点与难点：掌握电压、电流概念、基尔霍夫定律、二端口网络、电压源、电流源、欧姆定律；掌握单词。
Chapter 2 electronics 14学时Section 1 introductionSection 2 digital circuitsSection 3 logic circuit characteristics一、logic levels二、power supply voltage levels三、loading四、delay and frequency responseSection 4 diode-resistor gatesSection 5 the bipolar transistor as a switch or inverterSection 6 operational amplifiersSection 7 applications of operational amplifiers一、basic feedback concepts二、inverting amplifier三、noninverting amplifier四、differential amplifier五、nonlinear analog operations六、integrator, differentiator教学的重点与难点：掌握数字逻辑、门电路、转换电路、运算放大器及应用；掌握单词。
Chapter02 Electrical Components民航飞机电气系统2
to unreliable operation of systems, e.g.,
2
1
ELECTRIC WIRE CHART
18 16 14 12 10 8 6 4 2 1 1 2 0 0 3 0 4 0
20
AMPERES
3
40 30 25 20 18 16 14 12 10 9 8 7 6 5 1
15 12 10 9 8 7 6 5 4 3 2 .5
4
CURES 1 CONTINOUS RATING-AMPERES CABLES IN CONDUIT AND BUNDLES 2 CONTINUOUS RATING-AMPERES SINGLE CABLE IN FREE AIR 3 INTERMITTENT RATING-AMPERES MAXIMUM OF 2 MINUTES
example, the wire selected must be large enough to accommodate the required current without producing excessive heat or causing an excessive voltage drop. In addition, the insulation must prevent electrical leakage and be strong enough to resist damage caused by abrasion.
Chapter 2 Electrical Components
1
The satisfactory performance of any modern aircraft depends on the continuing reliability of electrical systems and subsystems. One of the most critical factors for obtaining a high degree of reliability
section 2-3
Section 3
Analog-Digital Conversion
Two important parameters must be considered in selecting a conversion technique or a variation of a conversion technique. One is the precision required in the analog-to-digital conversion; the other is the speed or the time interval allowed for the conversion. These two parameters are essentially incompatible because high-precision and highspeed conversions are difficult to achieve concurrently. High-speed or fast analog-to-digital conversion is a relative term, but in the context of digital computer conversion of binary data from
Section 3
Analog-Digital Conversion
Analog-to-digital conversion Only two basic techniques exist for analog-toto compare the analog voltage amplitude to a binary voltage scale in which the match yield the binary number that corresponds to the amplitude. The other technique is to integrate the analog signal and to use the measured time (a given number of clock pulses) for the amplitude of the integral to reach a value to establish an equivalent binary number. Each of the systems discussed below uses one or the other of these techniques.
电子与通信工程专业英语Unit 2
conductor is one ampere when the voltage applied to the conductor
电阻
假若将电池连接在导电材料上，一定数量的电流将流过此材料，流过材
料的电流取决于电池的电压、材料的截面积和材料自身的电阻率。对电流的
阻力叫电阻，用字母符号R表示。电阻的单位是欧姆．通常用表示。l欧姆的
定义为：当加到导体上的电压为l伏特时，将导体中的电流限制在1安培所需
要的电阻值。
Resistor, Capacitor and Inductor
Unit 2 Resistor, Capacitor and Inductor
is one volt. Larger amounts of resistance are commonly expressed in kiloohm (KΩ) and in megohm (MΩ).
电容器
电能可以储存在电场中，能够储存电能的装置叫电容器。电池被连接在两个金属板上，电荷将经
过很短的流动而汇集在一个电极板上。假若断开电池，电容器将保持电荷以
及与电荷相关的电压。
Resistor, Capacitor and Inductor
Unit 2 Resistor, Capacitor and Inductor
Unit 2 Resistor, Capacitor and Inductor
Resistor，Capacitor and Inductor
Translation Reading More Translating skills Text
Resistor, Capacitor and Inductor
A coil of many turns will have more inductance than one of few turns. Also if a coil is placed on an iron core its inductance will be greater than it was without the magnetic core. The unit of induct-
电气考研：电力电子课程英文版
The concept of power electronic devices
Power electronic devices：
are the electronic devices that can be directly used in the power processing circuits to convert or control electric power.
electronic devices
3
1.1 An introductory overview of power electronic devices
The concept and features Configuration of systems using power
electronic devices Classifications Major topics
A power electronic device usually has a third terminal —— control terminal to control the states of the device.
A power electronic device must have at least two terminals to allow power circuit current flow through.
12
Major topics for each device
Appearance, structure, and symbol Physics of operation
Characteristics
Static characteristics Switching characteristics
商务英语模拟题库卷2
商务英语模拟题库卷2I Translation.30%1. Curriculum Vitae ----------------- 16 求职信--------------------2. traffic jam ------------------ 17 收据--------------------3. sales executive ------------------- 18 折扣--------------------4. be responsible for -------------------- 19商务中心--------------------5. product promotion -------------------- 20 加班--------------------6. to apply for a job ------------------ 21白领---------------------7. annual report -------------------- 22 业绩--------------------8. cancel a meeting -------------------- 23海报--------------------9. blue collar -------------------- 24 工厂价交货--------------------10.holding company -------------------- 25 职业中介--------------------11.clerical job -------------------- 26 海关--------------------12.spare parts -------------------- 27碎纸机--------------------13.subsidiary -------------------- 28收入--------------------14.PLC -------------------- 29品牌--------------------15.fax machine -------------------- 30约会-------------------- II. Reading (20%)Question 1-20Look at question 1-20. In each question, which sentence is correct?For each question, mark one letter( A, B or C) on your answer sheet.A.an overcoatB. a uniform.C. a suit.2.A.be late for the meeting tomorrow.B.Take part in the meetingtomorrow.C.Not be at the meeting tomorrow.3.A.7 JulyB.8 JulyC.9 July4.A.improved.B.Remained steady.C.Decreased.5.A.a delivery date.rmation.C.An order.6.B.The conference will not take place.C.The conference will take place at a later date.7.A.before half past ten.B.at ten thirtyC.earlier than half past eleven.8.A.full details of what is in their session.B. a brief report about their sessionC. a proposal for their session.9.A.Wagner suite.B.Schumann suite.C.Bach Suite.10.A.doesn’t give presentations to large groups any more.B.often gave presentations to large groups in the past.C.often gives presentations to large groups.11.A.The goods are delayedB.The goods are lost.C.The goods are damaged.12.A.B.They will move to a new factory on 3 November.C.They will open the factory again on 3 November.13.A.He used to work for Townley Vehicles.B.He is applying for a job as a sales manager.C.He was employed by Weston Motors in the past.14.C.Contact us with your requirements when you open a new office.15.A.lower than expected.B.The same as expected.C.Higher than expected.16．The supervisorA.needs to know if there is no ink the photocopier.B.Should repair the photocopier if it prints badly.C.will tell you how to load the photocopier with ink.17.A.speak to reception after delivering goods.B.Unload vehicles at Reception.C.Call in at Reception before unloading.18.B.John will be late for his meeting on Tuesday.C.John hopes to see Jane on Tuesday.19.A.B.Staff must keep Personnel informed if they move house.C.Staff must inform Personnel of any company which changes address.20.A.Please ring Insurance direct Direct Back about the form before 28 September.B.Send bank the insurance form that you phoned about before 28 September.C.Insurance Direct have acknowledged receipt of your form dated 28 September.IV. Questions 1-5(10%)Look at the list below. It shows the contents page from a directory of suppliers.For question 1-5, decide which section (A—H) of the directory each person on theopposite page should consult.For each question, mark the correct letter (A—H) on your Answer Sheet.2.The company specializes in video-conferencing facilities.A.it is better value than other management books.B.it does not need to be read right through.C.it is about well-known people.2.The reviewer cannot accept Stuart’s opinions because StuartA.makes unreasonable complaints about the interviewees.B.writes too positively about the interviewees.C.has different attitudes toward different interviews.3.Reading the book make the reviewer think thatA.there are certain qualities which all Chief Executives need.B.it is different to discover how people really run a company.C.running a company is earlier than many people think.4.Which parts of the book did the reviewer most enjoy reading?A.How the interviewees became Chief Executives.B.What sort of people the interviewees are.C.The advice given by the interviewees.5.The reviewer recommends the book for people whoA.intend to set up in business.B.want to become senior managers.C.are outside the field of business.VI Writing (25%)1. A new designer, Mary Watts, has just joined your company.Write a memo to all staff:Telling them who the new employee isSaying what her responsibilities will beExplaining where her office is located.Write 30-40 words. (10%)_____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ _____________________________________________________________________ 2.Read this part of a letter your boss has received from Mrs. Astbury, a conferenceorganizer. Your boss has asked you to reply to the letter, accepting the invitation.Write your letter to Mrs. Astbury:Accepting the invitationSaying what the subject of your boss’s talk will beSaying why this subject is of interest to your boss at the momentRequesting a hotel room.Write 60-80 words.(15%)________________________________________________________________________________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________ ________________________________________________________________________Answer SheetI.Translation (30%)1__________________________________16______________________________ 2__________________________________17______________________________ 3__________________________________18______________________________ 4__________________________________19______________________________ 5__________________________________20______________________________ 6__________________________________21______________________________ 7__________________________________22______________________________ 8__________________________________23______________________________ 9__________________________________24______________________________ 10_________________________________25______________________________ 11_________________________________26______________________________ 12_________________________________27______________________________ 13_________________________________28______________________________ 14_________________________________29______________________________ 15_________________________________30______________________________ II Multiple choice (20%)1__________2____________3____________4_____________5____________6__________7____________8____________9______________10__________11_________12___________13___________14_____________15__________16_________17___________18___________19_____________20__________ III. Questions 1-5(5%)1__________2____________3____________4_____________5____________IV Cloze (10%)1__________2____________3____________4_____________5____________ 6__________7____________8____________9______________10__________ V. Reading Comprehension.(10%)1__________2____________3____________4_____________5____________2。
外文翻译—电力电子技术（英文+译文）
1 Power Electronic ConceptsPower electronics is a rapidly developing technology. Components are tting higher current and voltage ratings, the power losses decrease and the devices become more reliable. The devices are also very easy tocontrol with a mega scale power amplification. The prices are still going down pr. kVA and power converters are becoming attractive as a mean to improve the performance of a wind turbine. This chapter will discuss the standard power converter topologies from the simplest converters for starting up the turbine to advanced power converter topologies, where the whole power is flowing through the converter. Further, different park solutions using power electronics arealso discussed.1.1 Criteria for concept evaluationThe most common topologies are selected and discussed in respect to advantages and drawbacks. Very advanced power converters, where many extra devices are necessary in order to get a proper operation, are omitted.1.2 Power convertersMany different power converters can be used in wind turbine applications. In the case of using an induction generator, the power converter has to convert from a fixed voltage and frequency to a variable voltage and frequency. This may be implemented in many different ways, as it will be seen in the next section. Other generator types can demand other complex protection. However, the most used topology so far is a soft-starter, which is used during start up in order to limit the in-rush current and thereby reduce the disturbances to the grid.1.2.1 Soft starterThe soft starter is a power converter, which has been introduced to fixedspeed wind turbines to reduce the transient current during connection or disconnection of the generator to the grid. When the generator speed exceeds the synchronous speed, the soft-starter is connected. Using firing angle control of the thyristors in the soft starter the generator is smoothly connected to the grid over a predefined number of grid periods. An example of connection diagram for the softstarter with a generator is presented in Figure1.Figure 1. Connection diagram of soft starter with generators.The commutating devices are two thyristors for each phase. These are connected in anti-parallel. The relationship between the firing angle (﹤) and the resulting amplification of the soft starter is non-linear and depends additionally on the power factor of the connected element. In the case of a resistive load, may vary between 0 (full on) and 90 (full off) degrees, in the case of a purely inductive load between 90 (full on) and 180 (full off) degrees. For any power factor between 0 and 90 degrees, w ill be somewhere between the limits sketched in Figure 2.Figure 2. Control characteristic for a fully controlled soft starter.When the generator is completely connected to the grid a contactor (Kbyp) bypass the soft-starter in order to reduce the losses during normal operation. The soft-starter is very cheap and it is a standard converter in many wind turbines.1.2.2 Capacitor bankFor the power factor compensation of the reactive power in the generator, AC capacitor banks are used, as shown in Figure 3. The generators are normally compensated into whole power range. The switching of capacitors is done as a function of the average value of measured reactive power during a certain period.Figure 3. Capacitor bank configuration for power factor compensation ina wind turbine.The capacitor banks are usually mounted in the bottom of the tower or in thenacelle. In order to reduce the current at connection/disconnection of capacitors a coil (L) can be connected in series. The capacitors may be heavy loaded and damaged in the case of over-voltages to the grid and thereby they may increase the maintenance cost.1.2.3 Diode rectifierThe diode rectifier is the most common used topology in power electronic applications. For a three-phase system it consists of six diodes. It is shown in Figure 4.Figure 4. Diode rectifier for three-phase ac/dc conversionThe diode rectifier can only be used in one quadrant, it is simple and it is notpossible to control it. It could be used in some applications with a dc-bus.1.2.4 The back-to-back PWM-VSIThe back-to-back PWM-VSI is a bi-directional power converter consisting of two conventional PWM-VSI. The topology is shown in Figure 5.To achieve full control of the grid current, the DC-link voltage must be boosted to a level higher than the amplitude of the grid line-line voltage. The power flow of the grid side converter is controlled in orderto keep the DC-link voltage constant, while the control of the generator side is set to suit the magnetization demand and the reference speed. The control of the back-to-back PWM-VSI in the wind turbine application is described in several papers (Bogalecka, 1993), (Knowles-Spittle et al., 1998), (Pena et al., 1996), (Yifan & Longya, 1992), (Yifan & Longya, 1995).Figure 5. The back-to-back PWM-VSI converter topology.1.2.4.1 Advantages related to the use of the back-to-back PWM-VSIThe PWM-VSI is the most frequently used three-phase frequency converter. As a consequence of this, the knowledge available in the field is extensive and well established. The literature and the available documentation exceed that for any of the other converters considered in this survey. Furthermore, many manufacturers produce components especially designed for use in this type of converter (e.g., a transistor-pack comprising six bridge coupled transistors and anti paralleled diodes). Due to this, the component costs can be low compared to converters requiring components designed for a niche production.A technical advantage of the PWM-VSI is the capacitor decoupling between the grid inverter and the generator inverter. Besides affording some protection, this decoupling offers separate control of the two inverters, allowing compensation of asymmetry both on the generator side and on the grid side, independently.The inclusion of a boost inductance in the DC-link circuit increases the component count, but a positive effect is that the boost inductance reduces the demands on the performance of the grid side harmonic filter, and offers some protection of the converter against abnormal conditions on the grid.1.2.4.2 Disadvantages of applying the back-to-back PWM-VSIThis section highlights some of the reported disadvantages of the back-to-back PWM-VSI which justify the search for a more suitable alternative converter:In several papers concerning adjustable speed drives, the presence of the DC link capacitor is mentioned as a drawback, since it is heavy and bulky, it increases the costs and maybe of most importance, - it reduces the overall lifetime of the system. (Wen-Song & Ying-Yu, 1998); (Kim & Sul, 1993); (Siyoung Kim et al., 1998).Another important drawback of the back-to-back PWM-VSI is the switching losses. Every commutation in both the grid inverter and the generator inverter between the upper and lower DC-link branch is associated with a hard switching and a natural commutation. Since the back-to-back PWM-VSI consists of two inverters, the switching losses might be even more pronounced. The high switching speed to the grid may also require extra EMI-filters.To prevent high stresses on the generator insulation and to avoid bearing current problems (Salo & Tuusa, 1999), the voltage gradient may have to be limited by applying an output filter.1.2.5 Tandem converterThe tandem converter is quite a new topology and a few papers only have treated it up till now ((Marques & Verdelho, 1998); (Trzynadlowski et al., 1998a); (Trzynadlowski et al., 1998b)). However, the idea behind the converter is similar to those presented in ((Zhang et al., 1998b)), where the PWM-VSI is used as an active harmonic filter to compensate harmonic distortion. The topology of the tandem converter is shown inFigure 6.Figure 6. The tandem converter topology used in an induction generator wind turbine system.The tandem converter consists of a current source converter, CSC, in thefollowing designated the primary converter, and a back-to-back PWM-VSI, designated the secondary converter. Since the tandem converter consists of four controllable inverters, several degrees of freedom exist which enable sinusoidal input and sinusoidal output currents. However, in this context it is believed that the most advantageous control of the inverters is to control the primary converter to operate in square-wave current mode. Here, the switches in the CSC are turned on and off only once per fundamental period of the input- and output current respectively. In square wave current mode, the switches in the primary converter may either be GTO.s, or a series connection of an IGBT and a diode.Unlike the primary converter, the secondary converter has to operateat a high switching frequency, but the switched current is only a small fraction of the total load current. Figure 7 illustrates the current waveform for the primary converter, the secondary converter, is, and the total load current il.In order to achieve full control of the current to/from the back-to-back PWMVSI, the DC-link voltage is boosted to a level above the grid voltage. As mentioned, the control of the tandem converter is treated in only a few papers. However, the independent control of the CSC and the back-to-back PWM-VSI are both well established, (Mutschler & Meinhardt, 1998); (Nikolic & Jeftenic, 1998); (Salo & Tuusa, 1997); (Salo & Tuusa, 1999).Figure 7. Current waveform for the primary converter, ip, the secondary converter, is, and the total load current il.1.2.5.1Advantages in the use of the Tandem ConverterThe investigation of new converter topologies is commonly justifiedby thesearch for higher converter efficiency. Advantages of the tandem converter are the low switching frequency of the primary converter, and the low level of the switched current in the secondary converter. It is stated that the switching losses of a tandem inverter may be reduced by 70%, (Trzynadlowski et al., 1998a) in comparison with those of an equivalent VSI, and even though the conduction losses are higher for the tandem converter, the overall converter efficiency may be increased.Compared to the CSI, the voltage across the terminals of the tandem converter contains no voltage spikes since the DC-link capacitor of the secondary converter is always connected between each pair of input- and output lines (Trzynadlowski et al., 1998b).Concerning the dynamic properties, (Trzynadlowski et al., 1998a) states that the overall performance of the tandem converter is superior to both the CSC and the VSI. This is because current magnitude commands are handled by the voltage source converter, while phase-shift current commands are handled by the current source converter (Zhang et al., 1998b).Besides the main function, which is to compensate the current distortion introduced by the primary converter, the secondary converter may also act like an active resistor, providing damping of the primary inverter in light load conditions (Zhang et al., 1998b).1.2.5.2 Disadvantages of using the Tandem ConverterAn inherent obstacle to applying the tandem converter is the high number of components and sensors required. This increases the costs and complexity of both hardware and software. The complexity is justified by the redundancy of the system (Trzynadlowski et al., 1998a), however the system is only truly redundant if a reduction in power capability and performance is acceptable.Since the voltage across the generator terminals is set by the secondary inverter, the voltage stresses at the converter are high.Therefore the demands on the output filter are comparable to those when applying the back-to-back PWM-VSI.In the system shown in Figure 38, a problem for the tandem converter in comparison with the back-to-back PWM-VSI is the reduced generator voltage. By applying the CSI as the primary converter, only 0.866% of the grid voltage can be utilized. This means that the generator currents (and also the current through the switches) for the tandem converter must be higher in order to achieve the same power.1.2.6 Matrix converterIdeally, the matrix converter should be an all silicon solution with no passive components in the power circuit. The ideal conventional matrix converter topology is shown in Figure 8.Figure 8. The conventional matrix converter topology.The basic idea of the matrix converter is that a desired input current (to/from the supply), a desired output voltage and a desired output frequency may be obtained by properly connecting the output terminals of the converter to the input terminals of the converter. In order to protect the converter, the following two control rules must be complied with: Two (or three) switches in an output leg are never allowed to be on at the same time. All of the three output phases must be connected to an input phase at any instant of time. The actual combination of the switchesdepends on the modulation strategy.1.2.6.1 Advantages of using the Matrix ConverterThis section summarises some of the advantages of using the matrix converter in the control of an induction wind turbine generator. For a low output frequency of the converter the thermal stresses of the semiconductors in a conventional inverter are higher than those in a matrix converter. This arises from the fact that the semiconductors in a matrix converter are equally stressed, at least during every period of the grid voltage, while the period for the conventional inverter equals the output frequency. This reduces thethermal design problems for the matrix converter.Although the matrix converter includes six additional power switches compared to the back-to-back PWM-VSI, the absence of the DC-link capacitor may increase the efficiency and the lifetime for the converter (Schuster, 1998). Depending on the realization of the bi-directional switches, the switching losses of the matrix inverter may be less than those of the PWM-VSI, because the half of the switchings become natural commutations (soft switchings) (Wheeler & Grant, 1993).1.2.6.2 Disadvantages and problems of the matrix converterA disadvantage of the matrix converter is the intrinsic limitation of the output voltage. Without entering the over-modulation range, the maximum output voltage of the matrix converter is 0.866 times the input voltage. To achieve the same output power as the back-to-back PWM-VSI, the output current of the matrix converter has to be 1.15 times higher, giving rise to higher conducting losses in the converter (Wheeler & Grant, 1993).In many of the papers concerning the matrix converter, the unavailability of a true bi-directional switch is mentioned as one of the major obstacles for the propagation of the matrix converter. In the literature, three proposals for realizing a bi-directional switch exists. The diode embedded switch (Neft & Schauder, 1988) which acts like a truebi-directional switch, the common emitter switch and the common collector switch (Beasant et al., 1989).Since real switches do not have infinitesimal switching times (which is not desirable either) the commutation between two input phases constitutes a contradiction between the two basic control rules of the matrix converter. In the literature at least six different commutation strategies are reported, (Beasant et al., 1990); (Burany, 1989); (Jung & Gyu, 1991); (Hey et al., 1995); (Kwon et al., 1998); (Neft & Schauder, 1988). The most simple of the commutation strategies are those reported in (Beasant et al., 1990) and (Neft & Schauder, 1988), but neither of these strategies complies with the basic control rules.译文1 电力电子技术的内容电力电子技术是一门正在快速发展的技术,电力电子元器件有很高的额定电流和额定电压,它的功率减小元件变得更加可靠、耐用.这种元件还可以用来控制比它功率大很多倍的元件。
数字电子学参考文献及实验指南说明书
DIGITAL ELECTRONICSREFERENCESTheory:L.R. Fortney, Principles of Electronics, chapter 9F.J. Holler, J.P. Avery, S.R. Crouch, and C.G. Enke,Experiments in Electronics, Instrumentation and MicrocomputersDon Lancaster, TTL CookbookElectrical instruments and Circuit wiring:Chapter “Circuit Wiring Technique” in the Lab ManualChapter “Commonly Used Instruments” on The Oscilloscope and The Multimeter in the Lab ManualIINTRODUCTIONThis experiment is a basic introduction to digital logic. You should attempt it only if you either have some prior facility with circuit wiring or you have completed one of the electrical experiments (e.g., DC Circuits I, Charge and Discharge of a Capacitor).The experiment investigates how transistor devices are used to make various logic circuits. It is in two parts, each part having a value of one weight. Part I studies the Basic Unit, AND gates, OR gates, and binary adders. Part II studies Bistables, flip-flops, memories, and timing devices. All these components are available at the R esource C entre. The experiments do not investigate WHY a transistor behaves as it does, but concentrates on WHAT it does. As the circuits studied become progressively more complex, the experiments tend more towards logic than electronics.ΩΩΩµµFigure 1.- Circuit of the Basic UnitFigure 2a.The modules stack together, and are powered by 5 Volts DC from the power supply. The modules refer to a 6 V supply, but they work well at 5 Volts. This guide sheet, in addition to being divided into two parts, has a number of sections. When finished one section, turn off the power and remove all wires before going on to the next.PART II.1 - THE BASIC UNITThe Basic Unit is the simplest “blackbox ” (actually grey) in the experiment. It contains a single n-p-n transistor, with three parallel inputs and two outputs. The circuit diagram is shown in Figure 1.Turn over the Basic Unit and identify the components. The “b ”, “c ” and “e ” stand for the base,collector and emitter of the transistor, and since the emitter is connected to the 0 Volt reference level for both the input and output, this circuit is called a common emitter configuration.In this section we investigate output voltage versusinput voltage. Rather than using a second powersupply for the input voltage, we use a potentiometer asin Figure 2a. Wire up the potentiometer circuit anduse a voltmeter to investigate how it produces avariable voltage.Figure 2b.Figure 2b shows the circuit which can beused to show the amplifying properties ofthe transistor. Note that in this figure wehave not detailed the power supply. Inelectronic circuit diagrams the powersupply is usually not shown, and we willcontinue this convention; you may assumethat it is always there, however!Wire the power supply to the left side of the Basic Unit, red-to-red and black-to-black, then turn the system on. It is a good idea to keep the power supply on while you are wiring up your circuits. This way you can monitor any short circuits that you may encounter. You may measure V out for various V in by changing the potentiometer, paying particular attention to the range where V out changes most rapidly.When the potentiometer is set so V out is 3.0 Volts, small changes in V in give large changes in V out .Thus, when the transistor is “biased ” with the potentiometer, it may be used as an amplifier. What would the gain (= V out / V in ) be for your Basic Unit?Why do most non-inverting transistor amplifiers have an even (2,4,6, ...) number of transistors?If high voltage (5.0 Volts) is assigned the value 1, low volts the value 0, then the action of the Basic Unit can be summarized in the following Truth Table:INPUT 1INPUT 2OUTPUT 100110001011 0Verify this table for your Basic Unit. In logic circuits, this truth table defines a NOR gate, symbolized as:(Incidentally, the symbol on the Basic Unit stands for amplifier.)Before proceeding to further sections, turn off the power and remove all wires and the potentiometer from the Basic Unit so you may make a fresh start on Section 2.I.2 - "AND" GATESSet up the circuit shown in Figure 3 using three Basic Units. Inputs 1 and 2 can be just wires connected as shown. to make an input high, just plug into any of the sockets marked +6V; to make an input low, plug into any socket marked 0V. Your may turn the boxes over to verify that any +6V socket is equivalent.The indicator lights-up when the input is high, goes out when the input is low. Examine the circuit of the Indicator and explain how it works. Thus the Indicator shows whether the output of the circuit is high or low. (Most of our Indicators have 3 separate lights in one box.)Can you predict the truth table for this configuration? The logic diagram for these three NOR gates set up like this may help you. Now, measure the truth table for your circuit. In logic circuits, this device is called an AND gate,Figure 3.and is symbolized by :In fact, one of the supplied modules is an AND gate. Verify that the ready-made AND gate has the same logic as the one you have constructed. Then, turn the AND gate over and trace out its circuit to see why.I.3 - BINARY ADDITIONThe truth table for addition of two one digit binary numbers is:INPUT 1INPUT 2CARRY SUM0000100101011110The logic diagram for such a circuit is shown in Figure 4.Figure 4. - Binary AdditionVerify that this does satisfy the above truth table, and then build it using two Basic Units and an AND gate to prove that it works. This circuit is called a Half Adder.I.4 - "OR" GATEThis time we only supply the truth table, and challenge you to build the corresponding OR gate. Check your logic by testing your circuit.INPUT 1INPUT 2OUTPUT 1000101011111The symbol for an OR gate is:Note it is similar but not identical to the symbol for a NOR gate.Figure 5.- Full AdderFigure 6.I.5 - FULL ADDERSThis section discusses full binary addition, and contains no experiment.The adder of Section 3 can take two binary digits and add them. But when adding numbers with more than one bit, provision has to be made for the carry bit too. Such a Full Adder uses two Half Adders as in Section 3 plus an OR gate, as shown in Figure 5.Write out the truth table for the Full Adder.Addition of two 3-digit binary numbers, A and B, can thus be accomplished as shown in Figure 6.Just as the AND Gate combined 3 transistors as NOR gates in one box, this circuit could be put in one box too, but the number of transistors is large. (How many?) However, an Integrated Circuit can be `grown' with this circuitry and end up no larger than the head of a match.Figure 7. - Pin Assignments of 7402 CircuitPART IIINTRODUCTIONThis is a continuation of Part I. Here you investigate more advanced logic circuits.In Part I the circuits you studied were built up from combinations of simple n-p-n transistors. Most of your work in Part II will be using integrated circuits ("chips") from the family of Transistor-Transistor-Logic (TTL) components.You will find that whereas the Guide Sheet for Part I tended to be more-or-less explicit as to what to do, Part II is intended much more as an introduction that will get you thinking about what you want to do. You will find the references useful in exploring the question of what you wish to learn from this experiment.TTL circuits must never be driven by more than 5.0 Volts DC, and will notwork properly at less than 4.7 volts DC.II.1 - THE TTL "NOR" GATEFind the module labelled "7402". This box contains an integrated circuit containing four NOR gates.The numbered jacks on the top of the box are wired to the pins on the "chip" in accordance with Figure 7.Note that three pins are used for each NOR gate in the chip. Also, pin 14 is the +5V power lead for the circuit, and is also connected to the positive input for the power supply on the side of the box.Similarly, pin 7 is the 0V ground lead and is connected to the other power supply input on the side of the box.Verify that the logic of the 7402 NOR gate is identical to the Basic Unit using one of the gates in the module.In Part I you probably assumed (correctly) that any input not connected to anything would be low. This is not correct for TTL circuits. An unconnected input is unpredictable for TTL gates (though the tendency is that unconnected inputs swing "high". Thus all inputs (used or unused) for these circuits must be explicitly wired to be either high (5.0 Volts) or low(0 volts).The circuit for the NOR gate of the 7402 chip is not the simple transistor of the Basic Unit. For those interested, we recommend looking at the Appendix at the end of this Guide Sheet which discusses the TTL circuit. In any case, one reason why TTL is preferred to a simple transistor is related to the speed of response.You may compare the speed of the TTL NOR gate to the Basic Unit as follows.Using the oscilloscope in DC mode, set the signal generator so that it is deliveringa 100 kHz square wave with a DC offset so that the voltage varies between 0 Voltsand +5.0 volts. Do not connect the NOR gate until you have made this adjustment.If you are unsure how to use the oscilloscope, please refer to the “Commonly UsedInstruments” section on the “Oscilloscope” of th e Laboratory Manual .Keep the output of the generator wired to the oscilloscope, and also wire the output in parallel to one of the inputs of the NOR gate to be tested. Wire the output of thegate to the other beam of the oscilloscope.You may now measure the speed of response of the NOR gate to changing inputs.II.2 - "NAND" GATESThe NAND gate has the same logical relationship to the AND gate that the NOR gate has to the OR gate. Can you therefore predict the truth table for a NAND gate?The module labelled “7400’’ contains four NAND gates with pin assignments as shown in Figure 8. Use one of the NAND's in the 7400 to check your prediction of the truth table.For reasons explained in the Appendix, the NAND gate is the "Basic Unit" of TTL circuits, and thus has the lowest number in the 7400 series of integrated circuits.QUESTION: A seat belt warning system is to sound a warning buzzer unless all passengers have their seat belts fastened. The warning buzzer is to sound unless the driver's belt is fastened and each of the other seat belts are fastened or there is no weight on the seat. Assume there are "high" true logic signals representing the following: SS = start switch on; SB1 = driver seat belt fastened; SB2, SB3, SB4 = other belts fastened; W2, W3, W4 = weight sensed on seats 2, 3 and 4. Using 7400 and 7402 TTL chips, how can this be implemented? You will probably find that using the 7400 and 7402 modules to design, for example, an AND gate and then using the AND gate in your logic will be useful.Figure 8. - Pin Assignments of 7400 NANDFig 9. - NAND gates used to build a latchII.3 - LATCHES AND FLIP-FLOPSUsing two of the NAND gates in the 7400 module, wire the latch circuit shown in Figure 9.Q QConnect the outputs and to indicators, and the inputs S and R to switches. (S and R stand forQ QSet and Reset; the nomenclature and should be clear to you after you have investigated the circuit.)Hold down both switches simultaneously, so the inputs are High. Then momentarily release the switch connected to the gate whose output is Low and observe the result. Why is this circuit calledQ Qa latch? Why are the two outputs labelled and ? Can you follow the logic and explain why this circuit behaves as it does? Now use the other two NAND gates in the 7400 chip to modify yourlatch into the "S-R clocked flip-flop" shown in Figure 10.Figure 10. - S-R clocked flip-flopThe inputs S and R can be wires which you will connect to either High or Low voltage sources; the "Ck" input should be connected to the Switch module. Set the inputs S and R so they are opposite,leave the switch so the Ck input is Low, and power the circuit up. Observe what happens when the Switch is momentarily pressed and released. What happens when the Switch is pressed again? If you reverse the S and R inputs what happens? What happens when the switch is pressed and released?Thus, the S-R clocked flip flop acts as a one-bit memory circuit that allows, for example, the Q output to match the S input on the application of a positive level at Ck. The Ck stands for clock; in a computer, for example, the internal clock determines the cycle time for the memory.The Truth Table for the S-R clocked flip-flop is shown below.S nR n Q n+100Q n 10101011?Verify the validity of this truth table, and investigate the meaning of the "?" in the final row. Note that the subscripts n and n + 1 refer to the state after clock pulses n and n + 1 respectively.Figure 11.- D(delay) flip-flopFigure 12. - 7474 Dual D flip-flopNow modify your flip-flop circuit into the D (Delay) flip-flop shown in Figure 11. Investigate its truth table, and determine why this is called a delay flip-flop. Compare its logic to the 7474 circuit whose pin assignments are shown in Figure 12.II.4 - OTHER POSSIBILITIESWe have supplied you in module form two more TTL chips which in conjunction with various references can take you fairly far along your investigation of digital electronics. The pin assignments are shown in Figures 13, 14. For the really keen, after consultation with your demonstrator we can arrange to make available virtually the entire line of TTL chips in breadboard form.Also, in the "store-bought" modules are two non-integrated circuits, the Multivibrator and Bistable,which you may investigate.Figure 13. - 7408 Quad ANDFigure 14.- 7410 3-input NANDAPPENDIXIn the "store-bought" circuits studied in Part I, the basic circuit was the NOR gate, implemented by a single n-p-n transistor. All other logic functions were built up from this basic logic function. The basic circuit of the TTL systems studied in this experiment is the NAND gate, and other logic functions are built up from combinations of this gate. The logic of the NAND gate is studied in Section 2 of this Guide Sheet. Can you see, for example, how to build a NOR gate from NANDgates?Figure 15. - A TTL NAND gateFigure 16. - A DTL NAND gateThe circuit of the TTL NAND gate is shown if Figure 15.Q1 is a multiple-emitter transistor which is easily and cheaply built with modern integrated circuit technologies.In order to understand how this circuit works, look at Figure 16.The symbol stands for a diode.A diode presents essentially no resistance to current flowing in the direction of the "arrowhead", but gives essentially infinite resistance to currents attempting to flow in the opposite direction. Figure 16 shows a NAND gate constructed of diodes and a single transistor; such gates are called Diode Transistor Logic (DTL) gates. If at least one of the inputs is low, the diode D connected to this input conducts, and the voltage at point P is low. Thus diodes D1 and D2 are non conducting, and the input to the transistor Q is low, giving a high output. If all inputs are high, then all input diodes arecut off. Then the voltage at P tries to rise to Vcc effectively giving the transistor a high input at B,giving a low output.The TTL circuit of figure 15 has the same topology as Figure 16. The emitter junctions of Q1 act as the input diodes D of the DTL gate, and the collect of junction of Q1 replaces the diode D1 of Figure 16. The base-to-emitter diode of Q2 is used in place of the diode D2 of the DTL gate, and both circuits have an output transistor (Q3 or Q).Clamping diodes are often but not always included in the TTL NAND gate from each input to ground, with the anode grounded. These diodes are effectively out of the circuit for positive input signals, but for negative voltage excursions they limit the input to a safe value.(dh - 1982, jbv - 1990)。
《电子信息专业英语》课程标准9
《电子类专业英语》课程标准一、基本信息适用对象：电子类专业制定时间：课程代码：070590 所属系部：信息工程学院学分：2 学时：36制定人：批准人：二、课程的目标1、专业能力目标培养学生掌握电子方面的专业词汇，达到一定的对应用电子英语的翻译能力，并且能够依靠自身的专业背景知识阅读电子英文技术文献的应用能力。
2、方法能力目标学会学习、学会工作，拓展信息收集和应用能力，思考和解决问题的能力，学会系统设计方法和严谨工作作风。
3、社会能力目标学会共处，学会做人，具有良好的团队精神、职业道德和社会责任感。
三、整体教学设计思路1、课程定位本课程是高职院校电子类专业的专业基础课。
本课程的功能是培养学生掌握电子方面的专业词汇，达到一定的对应用电子英语的翻译能力，并且能够依靠自身的专业背景知识阅读电子英文技术文献的应用能力。
本课程是以《大学英语》、《模拟电子技术》、《数字电子技术》、《单片机应用》等课程的基本知识、技能为基础进行学习，后续课程中的专业技能课、《毕业综合实践》都要用到本课程的知识和技能。
本课程为学生进入电子企业，从事电子产品调试与维修、电子产品开发设计助理工程师等岗位打下基础。
2、课程开发思路本课程是在电子行业专家、电子企业专家、电子专业建设指导委员会参与下，在广泛市场调查、论证、研讨基础上经过多年的试点和反复改革的基础上进行开发与建设。
本课程以“电子类专业英语”电子产品开发生产过程为教学的主线，以工作过程为导向组织课程内容和课程教学。
本课程在教学中采用以工作过程为导向的项目化教学模式，在多媒体和计算机房进行理论与实践一体化教学。
教、学、做结合，学生在解决一个个项目任务的过程中，不仅获得了专业的知识和能力，也获得了方法能力和社会能力，达到了综合的职业能力的要求。
四、教学内容1、学时分配2、教学设计五、课程考核标准说明：1、在每个学习情境完成后，有相应的教学评价与考核。
考核依据项目操作过程、完成结果以及项目报告等。
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
Section 3 Analog-Digital Conversion
Two important parameters must be considered in selecting a conversion technique or a variation of a conversion technique. One is the precision required in the analog-to-digital conversion; the other is the speed or the time interval allowed for the conversion. These two parameters are essentially incompatible because high-precision and highspeed conversions are difficult to achieve concurrently. High-speed or fast analog-to-digital conversion is a relative term, but in the context of digital computer conversion of binary data from
Section 3 Analog-Digital Conversion
Fig.2-4 Block diagram of digital to analog converter
Section 3 Analog-Digital Conversion
The input register is a parallel-in, parallel-out device. The converter signal is used to clock the input data into the register where it is stored until the next converter signal is received.
Section 3 Analog-Digital Conversion
Analog-to-digital conversion Only two basic techniques exist for analog-to-
digital conversion (ADC). One is to compare the analog voltage amplitude to a binary voltage scale in which the match yield the binary number that corresponds to the amplitude. The other technique is to integrate the analog signal and to use the measured time (a given number of clock pulses) for the amplitude of the integral to reach a value to establish an equivalent binary number. Each of the systems discussed below uses one or the other of these techniques.
Some ways of sampling analog signals cannot be considered analog-to-digital conversion because the amplitude of the signal, an important aspect of the
Because many analog-to-digital conversions need not be made quickly, a high degree of precision is possible. The complexity and cost of attaining high precision, however, may modify the goal. The application intended for the conversion of the analog variable may determine what degree of digital precision is required.
Section 3 Analog-Digital Conversion
analog to digital, "high-speed" sampling intervals are about ten computer clock cycles rather than tens of thousands. Conversion in the interval of one microsecond is moderately fast but not limiting.
Section 3 Analog-Digital Conversion
information content, is not expressed in binary form. In the straightforward sampling of a sine wave, the amplitude is an essential part of the information content. In contrast, the conversion from an analog signal to a digital signal results in a binary number at each sampling point.
Байду номын сангаас
Section 3 Analog-Digital Conversion
they are equivalent to an ordinary SPDT switch controlled by the binary signal from the register. The switches feed a resistive summing network which converts each bit into its weighted current value and sums them for a total current. This total value is then fed the amplifier, which performs two functions, current to voltage conversion and scaling, so that the output voltage of the D/A converter will be the proper value.
Section 3 Analog-Digital Conversion
the voltage is derived from the sensitive element in an electrical circuit, as when a temperature sensitive resistor and a constant resistance form a voltage divider whose voltage is related directly to the temperature. Some transducers generate voltages directly, such as photoelectric elements and piezoelectric devices. Many voltage sources require voltage amplification to facilitate conversion from their analog values to binary numbers.
Section 3 Analog-Digital Conversion
The precision of analog-to-digital conversion is established by the number of binary bits, which correspond to maximum or full-scale analog value. Four bits allow the quantization in 0 to l5 equal intervals. For the binary representation of the amplitude to change by one bit, an analog amplitude must change by 6.25 percent. A byte (eight bits) allows a precision of 0.4 percent; seven bits of binary code correspond to approximately l percent encoding accuracy.
Section 3 Analog-Digital Conversion
Digital-to-analog conversion To convert a digital signal to analog, it is