电气专业英语课文翻译(7)

2. Input selector switches to funnel many input information channels switching sequentially to measuring

circuit, e.g., telephone stepping switches, crossbar switches, mercury jet switches, electromechanical switching, electronic multiplexers and manual selector for operator control.

3. Signal conditioning: scaler to adjust some signals to common input value, amplifier to build up low-level

signals, linearizer to remove any nonlinearizer, special bridge balance circuit for certain transducers and analog to digital converter for those analog input signals which will be required for digital readout.

4. Measuring circuit, where the measured variable is actually measured. Servoo-perated null-balance

potentiometer, digital potentiometer with mercury-wetted relay switching, and electronic detector.

5. System programmer, the heart of the system, for it controls the whole system, establishes the routine of the

instrument, selects measuring circuits, switches point, initiates logging and alarms, and provides time information.

6. Readout programmer, actuates readout and display devices.

7. Readout and display, provides means of logging and displaying all variables, recording off-normal points,

recording computed values on analog strip charts, typewriter log sheets, digital display lights, paper punched tape, magnetic tape, oscillograph record, printed tape and punched card.

8. Input signal scaling, span adjustment, zero adjustment, alarm set-point adjustment (by mechanical means),

potentiometers, pinboards, and fixed resistors.

9. Special computation circuits for averaging, multiplying, dividing, and totalizing. These are functions anf

components incorporated in information systems.

典型的数据处理系统的组成及功能：

1。传感器转换成便于测量变量的电压或电流输入信号传输到中央室，例如，热电偶，电阻温度计，电压力传感器，应变片，电流量传感器、气动压力电流转换器。

2。输入选择器开关漏斗多输入信息渠道交换顺序测量电路，例如，电话交换机加强，交叉开关，水银射流开关，机电开关，电子多路复用器和手动选择操作控制。

3。信号调理：缩放调整信号共同的输入值，建立低水平信号放大器，线性化，消除任何非线性，特殊桥梁平衡电路若干传感器和模拟数字转换器的模拟输入信号，将所需的数字读出。

4。测量电路，在测量变量实际上是衡量。伺服传动阀，调零电位器，数字电位器与汞润继电器开关，电子探测器。

5。系统程序员，系统的心脏，它控制整个系统，建立常规的仪器，以测量电路，开关，启动日志和警报，并提供时间信息。

6。读出编程器，读出和显示设备的驱动。

7。读出和显示，提供了手段，记录和显示的所有变量，记录正常点，记录计算值模拟条图，打字机记录表，数字显示灯，纸打孔磁带，磁带，示波器记录，印刷带和穿孔卡片。

8。输入信号缩放，调整，调零，报警设定点调整（通过机械手段），电位器，插接板，固定电阻器。

9。特殊计算电路平均，乘法，分割，和整体性。这些功能和组成部分纳入信息系统。

According to the Encyclopedia Americana，a system is "an aggregation ox assemblage of things so combined by nature or man as to form an integral and complex whale". Mathematical systems theory is the study，of the interruptions and behavior of such an assemblage of "things'* when subjected to certain conditions or inputs. The abstract nature of systems theory is due to the fact that it is concerned with mathematical properties rather than the physical faun of the constituent parts.

按照美工大百科全书的解释，所谓系统就是指“一个各种物体的集合，格局其他性质或人的愿望而结合起来以致形成一个集中、复杂的整体”。数学中的系统理论，就是对这种由若干“物体”过程的集合，当其受到某些条件和输入作用的影响后的行为和阻断进行研究的一门学问。系统理论的抽象性质源于这样的一个事实：系统理论更关心物体组成的部件的数学性质而不是其物理形式。

Control theory is mare often concerned with physical applications. A control system is considered to he any system which exists for the purpose or regulating or controlling the flow of energy，information, money，or other quantities in some desired fashion. In more general terms，a control system is an interconnection of many components or functional units in such a way as to produce a desired result. In this book，control theory is assumed to encompass all questions related to design and analysis of control systems.

控制理论通常与实际应用有关。一般认为，控制系统是任意一个这样的系统，其目的是为了以某种期望的方式来调节或控制诸如能量，信息，资金等等物理量的流动。从更一般的意义上讲，控制系统就是一个按照一定方式由很多元件或功能单元构成的结合体，期目的是为了获得期望的结果。本书中假定控制理论包括所有与控制理论包括所有系统设计和分析问题有关的内容。

Fig. 37. 1 is a general representation of an open loop control system, the ingot or control u(t) is selected hayed on the goals for the system and all available a priori knowledge about the system, The input is in no way influenced by the output of the system，represented by y(t)，If unexpected disturbances act upon an open-loop system, or if its behavior is not completely understood，them the output will not behave precisely as expected.

图３７.１是对对开环控制系统的一般性表示。输入变量或控制作用ｕ（ｔ）是根据本系统的目标以及所

Another general class of control systems is the closed-loop or f feedback control system，as illustrated in Fig.

37. 2, to the closed-loop system, the control u(t) is modified in some way by information about the behavior of the system output, A feedback system is often better able to cope with unexpected disturbances and uncertainties about the system's dynamic behavior.

另一类常见的控制系统是闭环或反馈控制系统，如图３７.２所示。闭环控制系统中，控制作用ｕ（ｔ）被以某种方式由于系统输出行为的信息所校正。一个反馈系统经常能更好的应付不期望的扰动作用以及系统动态性能的不确定性。

However，it need not be true that closed-look control is always superior to open-loop control. When the measured output has errors which are sufficiently large，and when unexpected disturbances are relatively unimportan …… 此处隐藏：5202字，全部文档内容请下载后查看。喜欢就下载吧 ……