专业英语重点语句译文

第一章1
①Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs (C).
电荷是构成物质的原子微粒的电气属性，它是以库仑为单位来度量的。

②We also know that the charge e on an electron is negative and equal in magnitude to 1.60210×10 19C, while a proton carries a positive charge of the same magnitude as the electron.
我们还知道电子的电量是负的并且在数值上等于1.602100×10-12C，而质子所带的正电量在数值上与电子相等。

③A unique feature of electric charge or electricity is the fact that it is mobile; that is, it can be transferred from one place to another, where it can be converted to another form of energy.
电荷或电的特性是其运动的特性，也就是，它可以从一个地方被移送到另一个地方，在此它可以被转换成另外一种形式的能量。

④Although we now know that current in metallic conductors is due to negatively charged electrons, we will follow the universally accepted convention that current is the net flow of positive charges.
虽然我们现在知道金属导体中的电流是由负电荷引起的，但我们将遵循通用的惯例，即把电流看作是正电荷的单纯的流动。

⑤The way we define current as i in Eq. (1-l) suggests that current need not be a constant-valued function, charge can vary with time in several ways that may be represented by different kinds of mathematical functions.
我们通过方程（1－1）定义电流的方式表明电流不必是一个恒值函数，电荷可以不同的方式随时间而变化，这些不同的方式可用各种数学函数表达出来。

⑥The voltage u ab between two points a and b in an electric circuit is the energy (or work) needed to move a unit charge from a to b;
电路中a、b两点间的电压等于从a到b移动单位电荷所需的能量（或所需做的功）。

⑦The power absorbed or supplied by an element is the product of the voltage across the element and the current through it.
某一元件吸收或提供的功率等于元件两端电压和通过它的电流的乘积。

第一章2
①An ideal independent source is an active element that provides a specified voltage or current that is completely independent of other circuit variables
一个理想的独立源是产生完全独立于其它电路变量的特定电压或电流的有源元件。

②The symbol for a voltage source having u volts across its terminals is shown in Fig.1-4(a).
该电压完全独立于流过元件的电流，在其端部具有u伏电压的电压源的符号如图1－4（a）所示
③Another symbol that is often used for a constant voltage source, such as a battery with U volts across its terminals, is shown in Fig.1-4(b).
对于恒定电压源我们通常使用另一种符号，例如在两端只有U伏电压的电池组，如图1－4（b）所示。

④We might observe at this point that the polarity marks on Fig.1-4(b) are redundant since the polarity could be defined by the positions of the longer and shorter lines.
我们可能已经注意到这一点，即图1－4（b）中的极性标号，是多余的因为我们可以根据长天线的位置符，确定电池极性。

⑤Thus if u is the voltage across the source and its current i is directed out of the positive terminal, then the source is delivering power, given by p = ui, to the external circuit.
因此如果u是电源两端的电压而电流i直接从其正端流出，那么该电源正在向对电路释放功率，由式p＝ui 算出。

⑥Since the control of the dependent source is achieved by a voltage or current of some other element in the circuit, and the source can be voltage or current, it follows that there are four possible types of dependent sources,
由于控制受控源的控制量来自于电路中其他元件的电压或电流，同时由于受控源可以是电压源或电流源。

⑦It should be noted that an ideal voltage source (dependent or independent) will produce any current required to ensure that the terminal voltage is as stated, whereas an ideal current source will produce the necessary voltage to ensure the stated current flow.
应该注意的是：一个理想电压源（独立或受控）可向电路提供以保证其端电压为规定值所需的任意电流，而电流源可向电路提供以保证其电流为规定值所必须的电压。

All the simple circuit elements that will be considered in the work that follows can be classified according to the relationship of the current through the element to the voltage across the element.
在下面进行的工作中我们要研究的简单电路元件可以根据流过元件的电流与元件两端的电压的关系进行分类。

Furthermore, we shall need to define special kinds of sources in which the source voltage or current depends upon a current or voltage elsewhere in the circuit; such sources will be termed dependent sources or controlled sources
此外，我们还要定义一些特殊类型的电源，这些电源的电压或电流取决于电路中其他的电流或电压，这样的电源将被称为非独立源或受控源。

第一章3
①The circuit element used to model the current-resisting behavior of a material is the resistor.
用来模拟材料阻流性能的电路元件是电阻，电阻是最简单的无源元件。

②Obviously, a straight line is the only graph possible for which the ratio of u(t) to i(t) is constant for all i(t).
显然，当u（t）与i（t）的比值对于所有的i（t）都为一恒定值时，其唯一可能的图形就是一条直线
③Resistors whose resistances do not remain constant for different terminal currents are known as nonlinear resistors.
对于不同端部电流而具有不同电阻的电阻器被称为非线性电阻器。

④In reality, all practical resistors are nonlinear because the electrical characteristics of all conductors are affected by environmental factors such as temperature.
事实上，所有实际电阻器都是非线性的，因为所有电阻器的电气性能会受到例如温度等的环境因素所影响。

①"Resistors" may be easily purchased or manufactured, but it is soon found that the voltage-current ratio of this physical device is reasonably constant only within certain ranges of current, voltage, or power and depends also on temperature and other environmental factors.
我们可以很容易地买到或制造电阻器，但很快我们发现这种物理元件只有当电流、电压或者功率处于特定范围时其电压——电流之比才是恒定的，并且这个比值也取决于温度以及其它环境因素。

第一章4
①A different class of relationship occurs because of the restriction that some specific type of network element places on the variables. ②Still another class of relationship is one between several variables of the same type which occurs as the result of the network configuration, i.e., the manner in which the various element of the network are interconnected.
一些不同类型的关系是由于某些特定类型的网络元件对变量的约束而产生的。

另一类关系是介于相同形式的一些变量之间的关系，这些变量是由于网络结构即网络的不同元件相互连接的方式而产生的。

③Kirchhoff's Current Law (KCL) states that the algebraic sum of currents entering a node (or a closed boundary) is zero.
基尔荷夫电流定律（KCL）表明流进一个节点（或一个闭合边界）的电流的代数和为0，
④An alternative form of KCL: The sum of the currents entering a node is equal to the sum of the currents leaving the node.
KCL定律的另一种形式是：流入节点的电流之和等于流出节点的电流之和。

⑤Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around a closed path (or loop) is zero.
基尔荷夫电压定律（KVL）表明环绕闭合线路（或回路）的电压的代数和为0，
⑥The sign on each voltage is the polarity of the terminal encountered first as we travel around the loop.
每个电压的符号就是当我们环绕回路时首先遇到的端部的极性。

第一章第五节基本分析方法
1、With the two techniques to be developed in this section, we can analyze almost any circuit by obtaining a set of simultaneous equations that are then solved to obtain the required values of current or voltage.
根据这一节所导出的这两种方法，我们就能够通过列出一套有关方程然后求解所需的电压和电流来分析几乎任何电路。

2、A convenient choice of voltages for many networks is the set of node voltages.
对于很多网络来说，选择节点电压（作为电路变量）是一个很方便的做法。

3、Frequently the reference node is chosen to be the node to which the largest number of branches are connected.
我们通常选择那个连接有最多条支路的节点作为参考节点。

4、The chassis may then be called ground, and it becomes the logical choice for the reference node.
这个底盘于是就可以被称为地，并在逻辑上被选作参考节点。

5、Clearly, simplification in writing the resulting equations is possible when the reference node is chosen to be a node with a large number of elements connected to it.
显然，连接有很多元件的节点被选为参考节点时，将结果方程进行简化是可以做到的。

6、identifying it by the ground connection shown.
用所示的连地符号来标明
7、These two voltages are sufficient, and the voltage between any other pair of nodes may be found in terms of them.
有这两个电压就够了，其它任意两个节点之间的电压可以根据这两个电压求出。

8、We do this by equating the total current leaving the node through the several conductances to the total source current entering the node.
我们可以通过使离开节点穿过n个电导的电流等于流入节点的总电流来做到这一点。

9、Using mesh currents instead of element currents as circuit variables is convenient and reduces the number of equations that must be solved simultaneously.
使用网孔电流代替元件电流作为电路变量很方便，因为它可以减少要求求解的联立方程的个数。

10、A planar circuit is one that can be drawn in a plane with no branches crossing one another; otherwise it is nonplanar.
平面电路是一个平面。

平面电路是一种可以画在平板上而其中没有相互交叉的支路的电路。

否则它就是非平面电路。

11、A mesh current is indicated by a curved arrow that almost closes on itself and is drawn inside the appropriate mesh, as shown in Fig.1-16.
网孔电流用一个几乎闭合的弯曲箭头符号标明并画在对应的网孔内，如图1－16所示。

12、Although the direction is arbitrary, we shall always choose clockwise mesh currents because
a certain error-minimizing symmetry then results in the equations.
虽然网孔电流的方向是任意的，但我们应始终选择网孔电流为顺时针方向，因为这样做将由于对称法使方程中出现的错误减少到最少程度。

第一章6
①We can proceed to our simplification of sinusoidal steady–state analysis by establishing the relationship between the phasor voltage and phasor current for each of the three passive elements.
通过建立三个无源元件的相电压和相电流之间的关系，我们可以进行正弦稳态分析的简化工作。

②We should note from Eq. (1-24) that the voltage and current relation is in phase, as illustrated in the phasor diagram in Fig.1-18.
在方程（1－24）中我们应当注意电压和电流之间的是关系相量之间的关系，正如图1－18中的相量图所示。

③The phase sequence is the time order in which the voltages pass through their respective maximum values.
相序就是每个电压经过其各自幅值的时间顺序。

④The phase sequence is determined by the order in which the phasors pass through a fixed point in the phasor diagram.
相序取决于相量图中相量经过一个固定点的顺序。

⑤This is due to the ease with which loads may be added or removed from each phase of a delta-connected load.
这是由于△形连接时可以方便地从△形连接的每一相负载上增加或减少负载。

On the other hand, delta-connected sources are not common in practice because of the circulating current that will result in the delta-mesh if the three-phase voltage are slightly unbalanced.
另一方面，如果三相电压稍有不平衡就会在三角形连接的网孔中产生循环电流，因此实际情况中三角形连接的电源并不常见。

The wye source connection is used for long distance transmission of electric power, where resistive losses (I 2R) should be minimal.
星型连接的电源用于长距离电力传输，此时电阻损耗(I2R)将达到最小。

This conversions from three-phase to single-phase is required in residential wiring because household lighting and appliances use single-phase power.
这种从三相到单相的转变用在住宅布线中因为家用照明和设备使用单相电源。

第二章1
①In every aspect of our increasingly technological society— whether it is science, engineering, medicine, music, maintenance, or even espionage—the role of electronics is large, and it is growing.
在我们日益发展的科技社会的方方面面——无论是在科学、工程、医药、音乐、维修方面甚至是在谍报方面——电子学的作用是巨大的，而且还将不断增强。

This information might involve speech and music, as in radio broadcasting, a physical quantity such as the temperature of the air in a room, or numerical data, such as the record of stock market transactions.
这种信息或许像无线电广播的演讲和音乐，或许是像室内温度的物理量，或许像股市交易记录的数字数据。

③A signal-processing system is an interconnection of components and devices that can accept an input signal or a group of input signals, operate on the signals in some fashion either to extract or improve the quality of the information, and present the information as an output in the proper form at the proper time.
一个信号处理系统是某些元件或设备之间的相互连接，这些元件和设备能够接收一个输入信号或一组输入信号，信号处理系统以某种方式来处理这些信号即提取这些信号或提高这些信号的品质，然后在适当的时间以适当的形式把这个信号表示为输出量。

Analog electronics pertains to those systems in which the electrical voltage and electrical current are analogous to physical quantities and vary continuously.
模拟电子涉及到这些系统中的电气电压和电流类似于物理量和连续变化。

Analog electronic circuits are carefully designed to make the electrical voltages and currents follow the input signal.
模拟电子电路都经过精心设计，使电机的电压和电流跟随输入信号。

第二章2
①The body of thought that is known collectively as symbolic logic established the principles for deriving mathematical proofs and singularly modified our understanding and the scope of mathematics.
这个思想的主体整体被称为符号逻辑，它建立了获取数学证法的基本原理并奇迹般地改变了我们的认识以及数学的范畴。

②Boole and others were interested in developing a systematic means of deciding whether a proposition in logic or mathematics was true or false, but we shall be concerned only with the validity of the output of digital devices.
布尔等人感兴趣的是推导出一种用来判断某个命题在逻辑上或在数学上是真还是假的系统性的方法，但我们要关注的仅仅是数字设备的输出的正确与否。

③In developing digital systems the easiest procedure is to put together conceptually the gates and connections to perform the assigned task in the most direct way.
在开发数字系统时最简单的做法是把逻辑门以及它们之间的连接根据概念排放在一起以最直接的方式完成设定的任务。

④The equivalent simplified combination of gates will probably be much less expensive and less difficult to assemble
逻辑门之间等效的简单的组合可能使得费用更加便宜而在装配上更加容易。

There are many different ways to build electronic circuits with input-output characteristics that correspond to the various digital operations.
构建具有对应于不同数字运算的输入－输出特性的电子电路的方法有很多种，某些类型的这些电路是以集成电路的形式制造的。

Occasionally, one must make connections between digital circuits constructed from logic families with input and output voltage ranges that are not compatible with one another.
偶尔我们必须连接由逻辑组合所构造的不同的数字电路，这些数字电路具有相互之间不一致的输入电压和输出电压范围。

第二章3
①The digital representation of the values is important for digital processing and analysis, for regulation and control, and for recording and transmitting the data that quantize them.
对于数字化处理和分析、调整和控制以及记录并将它们量化的数据进行传输这几方面来说，
②The clarity and fidelity of laser-read digital recordings of music and speech and the freedom of these recordings from background noise are recent advancements, but the human ear cannot convert binary data recorded on a disc to music or speech.
音乐或演讲的光读数字记录的清晰度和保真度以及将这些记录从背景杂音中提取出来是目前的先进技术，但人类的耳朵无法把唱片上的二进制数据记录转换成音乐或演讲
The transducer is the name of the device that produces a voltage or a current proportional to the physical phenomenon to which it responds.
传感器是一种元件的名称，这种元件产生了正比于它所反映的物理现象的电压和电流。

③the 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.
在某些情况下这个电压来自于电路中的敏感元件，比如当一个温敏电阻和一个恒电阻组成一个分压器，其电压直接与温度相关。

④The 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.
另一种方法是将模拟信号积分并在计算积分大小时采用测量时间（一个给定的时钟脉冲数）来求得某个值
以获得一个等效的二进制数，下面讨论的每一个系统采用了这些方法中的一种方法或另一种方法。

The bipolar inverter is the basic circuit from which most bipolar saturated logic circuit are developed, including diode-transistor logic (DTL) and transistor-transistor logic (TTL).
双极型反相器是一种基本电路，大多数双极型饱和逻辑电路包括二极管－晶体管逻辑电路（DTL）以及晶体管－晶体管逻辑电路（TTL）可由这种电路导出
Transistor-transistor logic, which evolved directly from DTL, provides reduced propagation delay times, as we will show.。

晶体管－晶体管逻辑电路，是从DTL电路直接演变而来，这种电路使传输延迟时间缩短，正如我们将展示的那样。

第二章4
①They became the foundation of analog computers, at one time analog computers were called "differential analyzers" because they are used to solve differential equations.
并成为模拟计算机的基础。

由于运算放大器被用来解差分方程，因此一段时期内模拟计算机被称为―差分分析器‖。

②The analog amplifier consists of a basic difference amplifier, implemented by feedback and other compensating amplifying circuits to give linear response, stability, freedom from drift, and other desirable properties.
模拟放大器由基本的差分放大器组成，通过反馈以及其它补偿放大电路实现线性反应、稳定性、来自漂移的自由度以及其它我们所期望的性能。

③Thus it is more difficult to isolate the long-term changes that arise from variations in temperature and power-supply voltage and from other effects that cause the output voltage to drift.
因此我们很难隔离由温度的变化和电源电压以及其它引起输出电压漂移的因素而产生的长效变化。

④The availability of operational amplifiers as integrated circuits in the form of dual in-line packages (DIPs) or in other compact forms makes the solution of analog signal problems analogous in many respects to the solution of digital logic problems, that is, through the interconnection of integrated circuits.
以双列直插式封装或以其它密封形式出现的运算放大器做成的集成电路的可用性使模拟信号问题在很多方面类似数字逻辑问题那样得到解决，也就是通过集成电路的相互连接得到解决。

⑤If two different positive voltages are applied separately to the two inputs, the output of the operational amplifier will be at the maximum (saturated) value if the voltage at the noninverting input is larger than the voltage at the inverting input
如果两个不同的正电压分别被加在两个输入端，而且非倒向输入端的电压大于倒向输入端的电压，那么运算放大器的输出端电压将处于最大值（饱和值）。

⑥We will see that an operational amplifier is an excellent voltage comparator because it produces a large voltage swing at the instant of crossing, when an earlier relation in voltage magnitudes is reversed by only a few microvolts.
我们将看到运算器是非常好的电压比较器，因为它在瞬间电压变换时产生很大的电压起伏。

此时仅仅几微伏的电压将使先前的电压大小关系产生逆转。

⑦When a portion of the output signal is returned to the input as negative feedback, the voltage difference cannot grow large because the output changes to minimize the voltage difference between the inputs.
当输出信号的一部分返回输入端作为负反馈，电压差就无法增大因为输出改变使输入端的电压差减小。

⑧To summarize, a good operational amplifier is characterized by a very large open-circuit gain of a million or so, an extremely small difference voltage between the inverting and the noninverting input terminals, a very high input impedance, and a small output impedance.
概括起来，一个好的运算放大器具有以下特性：
1. 非常大的大约一百万的开路增益，倒向输入端和非倒向输入端之间相当小的电压差；很高的输入阻抗以
及很小的输出阻抗。

概括起来，一个好的运算放大器具有以下特性：
⑨The other limitation is the rate at which most operational amplifiers can respond to a step change in the input signal
另外一个局限是大多数运算放大器对输入信号的改变所能起反应的速率。

⑩Operational amplifiers and digital logic gates used together allow data to be processed and analyzed with the greatest advantages of both technologies.
同时应用运算放大器和逻辑门的电路因为具有两种技术优势而允许进行数字处理和分析。

①The op-amp is prevalent in analog electronics, and can be thought of as another electronics device, in much the same way as the bipolar or field-effect transistor.
运算放大器在模拟电子学中很常用，并且它在很多方面与二极管或场效应管一样，可以被视为另一种电子设备。

②Op-amps, in conjunction with resistors and capacitors, were used in analog computer to perform mathematical operation to solve differential and integral equations.
运算放大器与电阻器和电容器连接在一起，被应用在模拟计算机中用来完成数学运算以求解微分方程和积分方程。

The maximum output was determined by specifying that the output transistor was saturation region and also by specifying a maximum collector current in the output transistor
最大输出取决于确定输出晶体管工作在饱和区并且确定输出晶体管的集电极电流处于最大值。

第三章3
①Such converters are very popular in the battery-operated power systems such as the uninterruptible power supplies (UPS) for hospitals, and AC motor drives.
这种转换器非常流行，如不间断电源（UPS）的医院，交流电机驱动器的电池供电的电源系统。

②Analyses of DC-AC converter circuits at low and high frequencies are very similar except that at high frequencies the parasitic capacitances and inductances, charge storage, and heat localizing problems in switching devices must be taken into account.
DC- AC转换器在低和高频率的电路分析是非常除了在寄生电容和电感，负责储存和热交换设备的本地化问题在高频率必须考虑采取类似的。

Input is from a DC source and the output is desired to be a sinusoidal voltage or current with
zero DC component, single-phase or three-phase signal.
输入来自直流源和输出所需的是一个正弦电压或电流零直流分量，单相或三相信号。

④Switches including the diodes are assumed to be ideal and unidirectional, that is, they have zero on-state losses, zero off-state losses, zero switching losses and unrestricted voltage or current carrying capabilities.
包括二极管开关被假定为理想和单向的，也就是说，它们具有零通态损耗，零断态损耗，开关损耗和零电压或电流进行不受限制的能力。

⑤Power flows from the converter to the load in the first and third quadrants and in the reverse direction in the second and fourth quadrants.
电源流量转换器中的第一和第三象限并在第二和第四象限反方向的负荷。

⑥Inverters derived from voltage source (VSI) are ideally suited for supplying power to a resistive and inductive load and the applications that require constant torque operation of AC motors.
从电压源（VSI）派生变频器非常适合供电到一个阻性和感性负载和应用要求的交流电机的恒转矩运行。

⑦The objective of harmonic profiling is to bolster the amplitude of the fundamental component of the output voltage and the elimination or reduction of high order harmonics.
谐波分析的目的是要加强对输出电压和消除或减少高次谐波的振幅基本组成部分。

⑧The pole of the switch stays in the first and second positions for equal amounts of time in a switching period.
交换机的极停留在等量的时间第一和第二的位置在一个开关周期。

⑨The third position of the switch is simulated by turning both switches off in VSI topologies and on in CSI topologies.
交换机的第三位是转折点VSI拓扑结构和拓扑结构在沪深两个开关关闭模拟。

⑩The two diodes provide the path for current flow from the load to the source as this may be required in an inverter operation involving more than one quadrant.
两个二极管提供电流从负载到源路径，因为这可能是一个逆变器，涉及多个象限操作。

①Designing an effective low-pass filter with cutoff frequency between the fundamental frequency and the first undesired harmonic frequency is a difficult task.
设计一个有效的低通截止频率之间的根本和第一个不受欢迎的谐波频率的频率过滤器是一个艰巨的任务。

Converter control refers to specifying the desired nominal operating condition and then regulating the converter so that it stays close to the nominal performance in the face of disturbances, noise and modeling errors.
转换器控制是指指定所需的标称工作状态，然后调节器，使其保持在接近的干扰，噪声和模型误差面对标称性能。