华立学院自动化英语期末考试段落翻译.doc

华立学院自动化专业英语期末考试段落翻译4.1Electric charge is as fundamental a constituent of our Universe as the mass and energy. Indeed, present physical theory supposes that all matter consists of particles, the principal attributes of which are mass and electric charge 电荷是我们的宇宙的一个基本要素就像质量和能量。确实，目前的物理理论假设，所有的物质粒子组成，其中的主要属性是质量和电荷。Two kinds of charge are known, arbitrarily designated positive and negative, which are characterized by the experimental observation that, under static conditions, separated like charges exert a mutual force of repulsion , whilst unlike charges ,under similar conditions ,exert a force of attraction .Under these conditions the field of force associated with charge is referred to as an electric field 两种已知的，被任意指定为正和负的电荷，通过实验观察表现出的特征是，它们在静态条件下，分开的同类电荷受到一个相互排斥的作用力，同时，不同类的电荷，在相同条件下，受到一个吸引的作用力。在这种情况下，与电荷有关的力场被称为电场。The voltage source maintains a constant terminal voltage irrespective of the current supplied to the load. It is important to appreciate that the voltage may be a function of, for example, time, temperature, pressure, etc. it is constant only with respect to variations of load. 电压源的端电压保持恒定的，不论对当前提供给负载。重要的是要明白，电压可能是一个函数关于，例如，时间，温度，压力等，它是恒定的只考虑负载的变化。The current source maintains a constant current in the load irrespective of the terminal voltage-which, in this case, is determined by the magnitude of the load. As with the voltage source, the generated current may depend on many other factors, but its one essential attribute is its independence of load.电流源保持恒定的电流在负载里，不论末端电压如何，既然这样，是由负载的大小决定的。与电压源一样，生成的电流可能取决于其他许多因素，但其本质属性是它独立负载。A circuit which is able to store electrostatic field energy is said to possess capacitance. The property is defined in terms of the electric charge stored per unit of potential difference at its terminals, according to the equation: q(t)=Cv(t), where C is the capacitance, the units of which are FARADS when v and q are in volts and coulombs, respectively. Hence, a capacitance of 1 F stores a charge of 1C for a terminal p. d. of 1V. Combining equations gives: I(t)=C dv(t)/dt with t in seconds.Thus, a current of 1A flows into a capacitance of 1 F when the terminal voltage changes at the rate of 1V/sec. 一个电路能够存储静电场能量，就是说拥有电容。他的性质被定义为根据两端电位差为1V时所储存的电量，根据公式：q(t)= Cv(t)，其中C是电容,单位是法拉，电压和电荷的单位分别是伏特和库仑。因此，1 F 的电容储存 1C的电荷为末端提供的电压是1V。结合等式为：I(t)=C dv(t)/dt，因此，当电压变化速率为每秒1V时，电容为1F，流入电容的电流为1A。5.1A signal is any physical variable whose magnitude or variation with time contains information. 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. The physical variables that can carry information in an electrical system are voltage and current. When we speak of signals, therefore, we refer implicitly to voltages or currents. However, most of the concepts we discuss can be applied directly to systems with different information-carrying variables. Thus, the behavior of a mechanical system (in which force and velocity are the variables) or a hydraulic system (in which pressure and flow rate are the variables) can often be modeled or represented by an equivalent electrical system. An understanding of the behavior of electrical systems, therefore, provides a basis for understanding a much broader range of phenomena. 信号就是其与时间有关的量值或变化包含信息的任何物理变量。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。在电气系统中能够载有信息的物理变量是电压和电流。因此当我们谈到“信号”，我们不 言而喻指的是电压和电流， 然而， 我们要讨论的大多数概念是可以被直接应用于载有不同信 息的变量的系统， 因此， 一个机械系统 （在这个系统中力和速度是其变量） 或者液压系统 （在 这个系统中压力和流速是其变量） 的性能通常可以用一个等效的电气系统来模拟或表示。 因 此，我们对于电气系统性能的理解为理解更宽领域的现象打下了一个基础A signal can carry information in two different forms. In an analog signal the continuous variation of the voltage or current with time carries the information. An example, in Fig.5-l, is the voltage produced by a thermocouple pair when the two junctions are at different temperatures.一个信号可以以两种形式来承载信息。 在一个模拟信号中电压或电流随时间而产生的连续变 化载有信息。在图 5-1 中，当一对热电偶的接头处于不同的温度时由热电偶所产生的电压就是一个例子。As the temperature difference between the two junctions varies, the magnitude of the voltage across the thermocouple pair also varies. The voltage thus provides an analog representation of the temperature difference. The other kind of signal is a digital signal. A digital signal is one that can take on values within two discrete ranges. Such signals are used to represent ON-OFF or YES-NO information. An ordinary household thermostat delivers a digital signal tocontrol the furnace. When the room temperature drops below a preset value, the thermostat switch closes turning on the furnace. Once the room temperature rises high enough, the switch opens turning off the furnace. The current through the switch provides a digital representation of the temperature variation: ON equals too cold while OFF equals not too cold. 当两个接头之间的温度差改变时，一对热电偶两端的电压也将改变。于是电压 就提供了温度差的模拟表现形式另一种的信号是数字信号。 数字信号是在两个离散的范围内能够呈现一定数值的信号。 这种 信号常用以表示“开关”或“是不是”信息。 一个普通的家用恒温器传递一种数字信号来控 制炉子当房间的温度下降到预定温度以下时， 恒温器的开关合上使炉子开始加热； 一旦房间 的温度上升到足够高， 开关就断开使炉子关闭。 流过开关的电流提供了温度变化的数字表示： ON 即为“太冷”而 OFF 即为“不太冷”A 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. Fig.2-2 illustrates the components in such a system. The central circles represent the two types of signal processing (digital and analog), while theblock between the two signal- processing blocks represents the conversion of an analog signal to equivalent digital form (A/D=Analog-to-Digital) and the reverse conversion of a digital signal to the corresponding analog form (D/A=Digital-to-Analog). The remaining blocks involve inputs and outputs getting signals into and out of the processing system. 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。图 2-2 显示了这样一个系统的组成部分。中间的圆圈代表了两种类型的信号处理（数字和模 拟） ，而处于信号处理框之间的方框表示模拟信号向等效数字形式（A/D 即模拟到数字）的 转换，以及从数字信号向相应的模拟形式（D/A 即数字到模拟）的逆转换。剩下的方框涉及 输入和输出取得信号以及从处理系统输出信号。 Many electrical signals derived from physical systems are obtained from devices called transducers. We have already encountered an example of an analog transducer, the thermocouple pair. It converts temperature difference (the physical variable) to a voltage (the electrical variable). Generally, a transducer is a device that converts a physical or mechanical variable to an equivalent voltage or current signal. Unlike the thermocouple example, however, most transducers require some form of electrical excitation to operate 从物理系统获得的很多电气信号是从被称为传感器的器件中输入的。 我们已经碰到了一个模 拟传感器的例子。即热电偶。它把温度的变化（物理变量）转换成电压（电气变量） 。通常， 传感器是一种将物理或机械变量转换成等效电压或电流信号的器件。 然而， 不同于热电偶例 子，大多数传感器需要一些形式的电激励以驱动传感器 The output from a system can be in many forms, depending on the use to be made of the information contained in the input signals. One can seek to display the information, either in analog form (using a meter, for example, in which the needle position indicates the size of the variable of interest) or in digital form (using a set of digital display elements that are lit up with a number corresponding to the variable of interest). Other possibilities are to convert the output to sound energy (with a loudspeaker), or to use the output asan input signal to another system, or to use the output as a control signal to initiate some action. 个系统的输出可以有多种形式， 这取决于包含在输入信号中的信息所起的作用。 我们可以选择何种方式显示这些信息，无论是以模拟形式（例如，使用一种仪表，仪表的指针的位置指 明我们所感兴趣的变量的大小）或是以数字形式（使用一套数字显示元件，显示对应于我们 所感兴趣的变量的数字） 。其它的可能的情况下是将输出转换成声能（利用扬声器） ，或是将 输出作为另一个系统的输入，或是利用输出作为控制信号来产生某个动作 The Decimal System Our present system of number has 10 separate symbols 0,1,2,3,.9，which are called Arabic numerals. We would be forced to stop at 9 or to invent more symbols if it were not for the use of positional notation. An example of earlier types of notation can be found in Roman numeral, which are essentially additive: III=I+I+I, XXV=X+X+V. New symbols (X,C,M, etc.) were used as the numbers increased in value. Thus V rather than IIIII=5. The only importance of position in Roman numerals lies in whether a system precedes or follows another symbol (IV=4), while (VI=6). The clumsiness of this system can easily be seen if we try to multiply XII by XIV. Calculating with Roman numerals was so difficult that early mathematicians were forced to perform arithmetic operations almost entirely on abaci, or counting boards, translating their results back into Roman-number form. Pencil-and-paper computations are unbelievably intricate and difficult in such systems. In fact, the ability to perform such operations as addition and multiplication was considered a great accomplishment in earlier civilization. 我们现在的数制有10个单独的符号0,1,2,3,.,9，这被称为阿拉伯数字。我们将被迫停止在9或发明更多的符号，如果它不供位置计数法使用。一个较早的符号类型的例子可以发现在罗马数字，是本质上加法的：III=I+I+I（3=1+1+1），XXV=X+X+V（25=10+10+5）。新的符号（X，C，M等）被用来做数值的增加。因此，V，而不是IIIII=5。唯一位置的重要性在罗马数字在于能否超前系统或在一个符号之后（IV= 4），而（VI= 6）。当我们试着12乘以14，这个系统的笨拙显而易见。用罗马数字计算很困难，以至于早期数学家被迫演示算术运算几乎完全在算盘或计数板上，再将结果转换回罗马数字形式。这种系统中，纸笔计算是难以置信的复杂和困难。事实上，有能力去演算加法和乘法运算是被认为一个伟大的成就在早期文明中。The base, or radix of a number system is defined as the number of different digits which can occur in each position in the number system. The decimal number system has a base, or radix, of 10. This means that the system has 10 different digits (0,1,2,9)any one of which may be used in each position is a number. History records the use of several other number systems. The quinary system, which has 5 for its base, was prevalent among Eskimos and North American Indians. Examples of the duodecimal system (base 12) may be seen in clocks, inches and feet and in dozens or grosses.这个基础，或一个数字系统的基数被定义为是不同的数字，可以出现在数字系统的任何位置。十进制数字系统有一个基础，或基数，10。这意味着系统有10个不同的数字（0,1,2，. 9）其中任何一个可以用于每个位置上是一个数字。历史记录了几个其他数字系统的使用。五进制，基数为5，流行于爱斯基摩人和北美印第安人中。十二进制（基数12）的例子，可看到在钟表，英寸，英尺，在打或总数。 The Binary System A seventeenth century German mathematician Gottfried Wilhelm von Leibniz, was an advocate of the binary number system which has 2 for a base, using only the symbols 0 and 1. If it seems strange for an eminent mathematician to advocate such a simple number system, it should be noted that he was also a philosopher. Leibnizs reasons for advocating the binary system seem to have been mystical. He felt there was great beauty in the analogy between zero, representing the void, and one, representing the Deity.Regardless of how good Leibnizs reasons for advocating it were, the binary system has become very popular in the last decade. Present day digital computers are constructed to operate in binary or binary coded number system, and present indications are that future machines will also be constructed to operate in these system. The basic elements in early computer were relays and switches. The operation of a switch, or relay, can be seen to be essentially binary in nature. That is the switch is either on (1)or off (0). The principal circuit elements in more modem computers are transistors similar to those used in radios and television sets. The desire for reliability led designers to use these devices so that they were essentially in one of two states. Fully conduction or non-conducting. A simple analogy may be made between this type of circuit and an electric light. At any given time the light (or transistor) is either on (conducting) or off (not conduction), Even after a bulb is old and weak, it is generally easy to tell if it is on or off. The same sort of thing may be seen in radios. As a radio ages the volume generally decreases, and we compensate by turning the volume control up, even when the radio becomes very weak, however, it is still possible to tell easily whether it is on or off. Because of the large number of electronic parts used in computers, it is highly desirable to utilize them in such a manner that slight changes in their characteristics will not affect their performance. The best way of accomplishing this is using circuits which are basically bistable (having two possible states).二元体系 一个17世纪德国数学家戈特弗里德威廉冯莱布尼茨，是一个二进制数字系统已为基地2倡导者，只用符号0和1。如果它似乎一个杰出的数学家奇怪提倡这样一个简单的数字系统，但应该指出的是，他也是一个哲学家。主张对莱布尼茨的二进制系统的理由似乎已经神秘。他感到有大美中之间的类比零，代表空白，一，代表神。 不管如何提倡它是良好的，在双星系统，已成为在过去10年非常流行的莱布尼茨的理由。现今的数码电脑操作构造二进制或二进制数字编码系统，目前迹象显示，未来也将兴建机器的运作这些系统。 在早期的计算机的基本元素，继电器和开关。一个交换机或中继操作，可以被看作是二元性的本质。这是开关或者是：（1）或关闭（0）。 在现代的计算机更主要的电路元件是晶体管类似收音机和电视机所使用的。欲望导致的可靠性设计人员使用这些设备，使他们在本质上的两个国家之一。充分传导或不导电的。一个简单的比喻可能作出这样的电路之间的类型和电灯。在任何特定时间的光（或晶体管）无论是在（进行中）或关闭（不导电），即使在一个灯泡是年老体弱，一般容易分辨它是打开或关闭。 同一类的东西可能会出现在收音机。 由于无线电年龄普遍降低音量，我们赔偿转动音量控制，甚至当收音机变得非常薄弱，但是，它仍然可以轻松地告诉无论是打开或关闭。由于在电脑中使用的大量电子零件，这是非常可取的，以这样的方式利用他们，在他们的特色略有变化将不会影响其性能。为完成这基本上是使用双稳态电路（有两个可能的状态最好的办法）。5.2Electric charge is as fundamental a constituent of our Universe as the mass and energy. Indeed, present physical theory supposes that all matter consists of particles, the principal attributes of which are mass and electric charge 电荷跟质量和能量一样是构成宇宙的基本元素。确实，目前的物理理论假设，所有的物质粒子组成，其中的主要属性是质量和电荷。Two kinds of charge are known, arbitrarily designated positive and negative, which are characterized by the experimental observation that, under static conditions, separated like charges exert a mutual force of repulsion , whilst unlike charges ,under similar conditions ,exert a force of attraction .Under these conditions the field of force associated with charge is referred to as an electric field 两种已知的，被任意指定为正和负的电荷，通过实验观察表现出的特征是，它们在静态条件下，分开的同类电荷受到一个相互排斥的作用力，同时，不同类的电荷，在相同条件下，受到一个吸引的作用力。在这种情况下，与电荷有关的力场被称为电场。The voltage source maintains a constant terminal voltage irrespective of the current supplied to the load. It is important to appreciate that the voltage may be a function of, for example, time, temperature, pressure, etc. it is constant only with respect to variations of load. 电压源的端电压保持恒定的，不论对当前提供给负载。重要的是要明白，电压可能是一个函数关于，例如，时间，温度，压力等，只有在考虑负载的变化它是恒定的。The current source maintains a constant current in the load irrespective of the terminal voltage-which, in this case, is determined by the magnitude of the load. As with the voltage source, the generated current may depend on many other factors, but its one essential attribute is its independence of load.电流源保持恒定的电流，与由负载大小所决定的电压无关。正如电压源，电流源所产生的电流取决于很多因素，但是它的一个重要属性是它是独立的负载A circuit which is able to store electrostatic field energy is said to possess capacitance. The property is defined in terms of the electric charge stored per unit of potential difference at its terminals, according to the equation: q(t)=Cv(t), where C is the capacitance, the units of which are FARADS when v and q are in volts and coulombs, respectively. Hence, a capacitance of 1 F stores a charge of 1C for a terminal p. d. of 1V. Combining equations gives: I(t)=C dv(t)/dt with t in seconds.Thus, a current of 1A flows into a capacitance of 1 F when the terminal voltage changes at the rate of 1V/sec. 一个电路能够存储静电场能量，就是说拥有电容。他的性质被定义为根据两端电位差为1V时所储存的电量，根据公式：q(t)= Cv(t)，其中C是电容,单位是法拉，电压和电荷的单位分别是伏特和库仑。因此，1 F 的电容储存 1C的电荷为末端提供的电压是1V。结合等式为：I(t)=C dv(t)/dt，因此，当电压变化速率为每秒1V时，电容为1F，流入电容的电流为1A。As the temperature difference between the two junctions varies, the magnitude of the voltage across the thermocouple pair also varies. The voltage thus provides an analog representation of the temperature difference. The other kind of signal is a digital signal. A digital signal is one that can take on values within two discrete ranges. Such signals are used to represent ON-OFF or YES-NO informationAn ordinary household thermostat delivers a digital signal to control the furnace. When the room temperature drops below a preset value, the thermostat switch closes turning ON the furnace. Once the room temperature rises high enough, the switch opens turning OFF the furnace. The current through the switch provides a digital representation variation: On equals “too cold” while OFF equals “not too cold ”. 由于两个节点间的温度差不同，热电偶的电压大小也不同。电压因此提供一个模拟（信号）代表温度差。另一种信号是数字信号。一个数字信号是可以在两个离散范围里取值的。这样的信号被用于代表开-关或是-非的信息。一个普通家用自动调温器传送一个数字信号去控制火炉，当室内温度下降到低于一个预设值，自动调温器开关闭合打开炉子。当室内温度上升到足够高，开关打开关闭炉子。流过按钮的电流提供一个数字代表变量：ON等于“太冷”当OFF等于“不太冷”。Our present system of number has 10 separate symbols 0,1,2,3,.9，which are called Arabic numerals. We would be forced to stop at 9 or to invent more symbols if it were not for the use of positional notation. An example of earlier types of notation can be found in Roman numeral, which are essentially additive: III=I+I+I, XXV=X+X+V. New symbols (X,C,M, etc.) were used as the numbers increased in value. Thus V rather than IIIII=5. The only importance of position in Roman numerals lies in whether a system precedes or follows another symbol (IV=4), while (VI=6). The clumsiness of this system can easily be seen if we try to multiply XII by XIV. Calculating with Roman numerals was so difficult that early mathematicians were forced to perform arithmetic operations almost entirely on abaci, or counting boards, translating their results back into Roman-number form. Pencil-and-paper computations are unbelievably intricate and difficult in such systems. In fact, the ability to perform such operations as addition and multiplication was considered a great accomplishment in earlier civilization.我们现在的数制有10个单独的符号0,1,2,3,.,9，这被称为阿拉伯数字。我们将被迫停止在9或发明更多的符号，如果它不供位置计数法使用。一个较早的符号类型的例子可以发现在罗马数字，是本质上加法的：III=I+I+I（3=1+1+1），XXV=X+X+V（25=10+10+5）。新的符号（X，C，M等）被用来做数值的增加。因此，V，而不是IIIII=5。唯一位置的重要性在罗马数字在于能否超前系统或在一个符号之后（IV= 4），而（VI= 6）。当我们试着12乘以14，这个系统的笨拙显而易见。用罗马数字计算很困难，以至于早期数学家被迫演示算术运算几乎完全在算盘或计数板上，再将结果转换回罗马数字形式。这种系统中，纸笔计算是难以置信的复杂和困难。事实上，有能力去演算加法和乘法运算是被认为一个伟大的成就在早期文明中。The base, or radix of a number system is defined as the number of different digits which can occur in each position in the number system. The decimal number system has a base, or radix, of 10. This means that the system has 10 different digits (0,1,2,9)any one of which may be used in ea