自动化专业英语期末复习课文与翻译
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An electrical circuit or network is
composed of elements such as resistors , inductors
, and
capacitors connected together in some
manner .If the network contains no energy sources
, such as
batteries or electrical generators,it
is known as a passive the other hand, if one or
more energy sources are present , the
resultant combination is an active network. In
studying the
behavior of an electrical
network,we are interested in determining the
voltages and currents that
exist within the
circuit. Since a network is composed of passive
circuit elements,we must first
define the
electrical characteristics of these elements.
电路或电网络由以某种方式连接的电阻器、电感器和电容器等元件组成。如果网络不
包含能源，如电池或
发电机，那么就被称作无源网络。换句话说，如果存在一个或多个能源，
那么组合的结果为有源网络。在
研究电网络的特性时，我们感兴趣的是确定电路中的电压和
电流。因为网络由无源电路元件组成，所以必
须首先定义这些元件的电特性.
In the case of a resistor,
the voltage-current relationship is given by Ohm's
law, which ststes
that the voltage across the
resistor is equal to the current through the
resistor multiplied by the
value of the
resistance. Mathematically, this is expressed as
u=iR where u=voltage , V;
i=current, A;
R=resistance Ω.
就电阻来说，电压-电流的关系由欧姆定律给出，欧姆定律指出
：电阻两端的电压等于
电阻上流过的电流乘以电阻值。在数学上表达为: u=iR
(1-1A-1)式中 u=电压，伏特；i =电流，
安培；R = 电阻，欧姆。
The voltage across a pure inductor is defined by
Faraday's law ,which states that the voltage
across the inductor is proportional to the
rate of change with time of the current through
the
inductor. Thus we have u=Ldidt where
didt=rate of change of current ,As; L=inductance
,H.
纯电感电压由法拉第定律定义，法拉第定律指出：电感两端的电压正比于流过电感的电<
br>流随时间的变化率。因此可得到：U=Ldidt 式中 didt = 电流变化率， 安培秒； L
= 感应
系数， 享利。
The voltage developed across
a capacitor is proportional to the electric charge
q
accumulating on the plates of the
capacitor. Since the accumulation of charge may be
expressed as
the summation, or integral , of
the charge increments dq, we have the equation
u=1c fdq
where the capacitance C is the
proportionality constant relating voltage and
charge. By
definition, current equals the rate
of change of charge with time and is expressed as
i=dqdt. Thus
an increment of charge dq is
equal to the current multiplied by the
corresponding time increment,
or dq=i dt.
电容两端建立的电压正比于电容两极板上积累的电荷q
。因为电荷的积累可表示为电
荷增量dq的和或积分，因此得到的等式为 u= 1c fdq，式中电
容量C是与电压和电荷相关
的比例常数。由定义可知，电流等于电荷随时间的变化率，可表示为i =
dqdt。因此电荷增
量dq 等于电流乘以相应的时间增量，或dq = i dt， 那么等式
(1-1A-3) 可写为式中 C = 电
容量，法拉。
A common
method of analyzing an electrical network is mesh
or loop analysis. The
fundamental law that is
applied in this method is Kirchhoff's first law,
which states that the
algebraic sun of the
voltages around a closed loop is 0 ,or , in any
closed loop , the sum of the
voltage rises
must equal the sum of the voltage drops. Mesh
analysis consists of assuming that
currents-
termed loop currents-flow in each loop of a
network ,algebraically summing the voltage
drops around each loop ,and setting each sum
equal to 0.
分析电网络的一般方法是网孔分析法或回路分析法。应用于此方法的基
本定律是基尔霍
夫第一定律，基尔霍夫第一定律指出：一个闭合回路中的电压代数和为0，换句话说，任
一
闭合回路中的电压升等于电压降。网孔分析指的是：假设有一个电流——即所谓的回路
电流
——流过电路中的每一个回 路，求每一个回路电压降的代数和，并令其为零
One problem with electronic devices corresponding
to the generalized amplifiers is that the
gains, Au or Ai, depend upon internal
properties of the two-port system(u,β，Ri ,Ro,
etc). This
makes design difficult since these
parameters usually vary from device ,as well as
with
temperature. The operational amplifier,
or Op-Amp, is designed to minimize this dependence
and
to maximze the ease of design. An Op-Amp
is an integrated circuit that has many component
parts
such as resistors and transistors built
into the device. At this point we will make no
attempt to
describe these inner workings.
运算放大器像广义放大器这样的电子器件存在的一个问题就是它们的增益AU或AI取决
于双端口系统(
m、b、RI、Ro,等)的内部特性。器件之间参数的分散性和温度漂移给设计工
作增加了难度。设计
运算放大器或Op-Amp的目的就是使它尽可能的减少对其内部参数的
依赖性、最大程度地简化设计工
作。运算放大器是一个集成电路，在它内部有许多电阻、晶
体管等元件。就此而言，我们不再描述这些元
件的内部工作原理。
Integrated circuit technology
allows construction of many amplifier circuits on
a single
composite
集成电路技术使得在非常小的一块半导体材料的复合
“芯片”上可以安装许多放大器电路。
The first law states that
in normal Op-Amp circuits we may assume that the
voltage difference
between the input terminals
is zero, that is , U+=U-
第一个定律指出：在一般运算放大器电路中，可以假设输入
端间的电压为零，也就是说
U+=U-
The second law states
that in normal Op-Amp circuits both of the input
currents may be assumed
to be zero: I+=I-=0
第二个定律指出：在一般运算放大器电路中，两个输入电流可被假定为零：I+=I-=0
The two-valued variables which we have been
discussing are often called logical variables,
while the operations such as the OR operation
and the AND operation are referred to as logical
operations. We shall now briefly discuss the
relevance of such terminology, and in so doing we
shall bing out the special aptness of the
designations and to identify the possible
values of a variable.
逻辑变量我们讨论的双值变量通常叫做逻
辑变量，而象或和与这样的操作被称为逻辑操
作。现在我们将简要地讨论一下这些术语之间的关联，并在
此过程中，阐明用标示“真”和“假”
来识别一个变量的可能值的特殊用途。
The circuit of Fig.1-3A-1, showing a pair of
cross-coupled NOR gates, is called a flip-flop,
It has a pair of input terminals S and R,
standing for
these symbols S and R not only to
designate the terminals but also to specify the
logical level at
the terminals. Thus ,S=1
indicates that a voltage corresponding to logic
level 1 is normally present
at terminal S .
Similarly ,the output terminals and the
corresponding output logic levels are Q and
Q.
In this notation we have explicitly taken account
of the fact that in normal operation, as we
shall see, the logic levels at the outputs are
complementary.
图1-3A-1给出的一对交叉连接的或非门电路被称为触发器。其有一对输入端S 和
R
，分别代表“置位”和“复位”。我们不仅用符号S 和R
标明端点，而且指定端点的逻辑电
平。因此，通常S=1指的是对应于逻辑电平为1的电压出现在S
端。相似的，输出端和相
应的输出逻辑电平为Q和 非Q。使用这样的符号时，我们已经明确了一个事实
，即在我们
下面将看到的符号操作中，输出的逻辑电平是互补的。
The types of commercially available DC motors
basically fall into four categories:(1)
permanent-magnet DC motors, (2) series-wound
DC motors, (3) shunt-wound DC motors, and (4)
compound-wound DC motors. Each of these motors
has different characteristics due to its basic
circuit arrangement and physical properties.
现在可以买到的直流电机基本上有四种：⑴永磁直流电机，⑵串励直流电机，⑶并励
直流电机，⑷复励直流电机。每种类型的电动机由于其基本电路和物理特性的不同而具有不
同的机械特性
。
The permanent-magnet DC motors ,show in
Fig.1-5A-1,is constructed in the same manner as
its DC generator counterpart.
永磁直流电机，如图1-5A-1所示，是用与直流发电机同样的方法建造的。
The
manner in which the armature and filed circuits of
a DC motors are connected determines
its basic
characteristics.
直流电机电枢和激磁电路的连接方式确定了直流电机的基本特性。
The word control
is usually taken to mean regulate, direct, or
command. Control systems
abound in our
environment. In the most abstract sense it is
possible to consider every physical
object as
a control system.
控制一词的含义一般是调节、指导或者命令。控制系统大量存在
于我们周围。在最抽象的意
义上说，每个物理对象都是一个控制系统。
Control
systems designed by hunmans are used to extend
their physical capabilities, to
compensate for
their physical limitations, to relieve them of
routine or tedious task,or to save
money.
控制系统被人们用来扩展自己的能力，补偿生理上的限制，或把自己从常规、单调的工作
中解脱出来，或
者用来节省开支。
Control theory itself has two
categories:classical and modern. Classical control
theory, which
had its start during World War
II, can be characterized by the transfer function
concept with
analysis and design principally
in the Laplace and frequency domains. Modern
control theory has
arisen with the advent of
high-speed digital computers and can be
characterized by the state
variable concept
with emphasis on matrix algebra and with analysis
and design principally in the
time domain. As
might be expected, each approach has its
advantages and disadvantages as well
as its
proponents and detractors..
控制理论本身分成两个部分：经典和现代
。经典控制理论始于二次大战以传递函数的概
念为特征，分析和设计主要在拉普拉斯域和频域内进行。现
代控制理论是随着高速数字计算
机的出现而发展起来的。它以状态变量的概念为特征，重点在于矩阵代数
，分析和设计主要
在时域。每种方法都有其优点和缺点，也各有其倡导者和反对者。
Open-loop and closed-loop control systems (see
Fig.2-1A-1). An open-loop system is one in
which the control action is independent of the
output. A closed-loop system, however, the input
of
the plant is somehow dependent on the
actual output.
开环和闭环系统（如图2-1A-1）：开环控制系统是控制行为与输
出无关的系统。而闭环系统，
其被控对象的输入在某种程度上依赖于实际的输出。
The
stability of a continuous or discrete-time system
is determined by its response to inputs
or
disturbance. Intuitively, a stable system is one
that remains at rest (or in equilibrium) unless
excited by an external source and returns to
rest if all excitations are removed.
连续或离散系统的
稳定性由其对输入或者干扰的响应决定。直观地说，如果一个系统是稳
定的，则其停留在
稳态（或者平衡点），除非是受到外部激励，且当外部激励去除后，输出
又回到稳态点。
The characteristic equation is formed by
setting the denominator polynomial equal to zero.
将分母多项式等于零即得到特征方程
So,a necessary and
sufficient condition for the system to be stable
is that the roots of the
characteristic
equation have negative real ensures that the
impulse response will decay
exponentially with
time.
因此，系统稳定的充分必要条件就是特征方程根的实部为负。这保证脉冲响应将按指数
形式随时间衰减。
The Routh criterion:All the roots of the
characteristic equation have negative real parts
if and
only if the elements of the first
column of the Routh table have the same sign.
Otherwise, the
number of roots with positive
real parts is equal to the number of changes of
sign.
劳斯判据：当且仅当劳斯表第一行元素有相同的符号时，特征方程的根具有负实数。反之，
具有正式部的特征根的个数等于劳斯表第一列元素变号次数。
For a simple
lag, two feature are important:
1.
stability:for system stability, the system pole(s)
must lie in the left half of the s-plane, so that
the transient of the system decays instead of
grows as t increases.
2. speed of response :to
speed up the response of the system（i.e., to
reduce its time constant
T）,the pole-1T must
be moved left.
简单滞后有两个重要特征。
1. 稳定性：对于系统稳定
性，系统极点必须位于s平面的左半边，这样系统暂态衰减，
而不是随时间增加而增加。
2. 响应速度：加速系统的响应（即减小时间常数）， 极点1T应左移
Forξ>1,these
poles are on the negative real axis, on both sides
of-Wn; the transient is a sum of two
decaying
exponentials, each with its own time constant. The
exponential corresponding to the pole
closest
to the origin has the largest time constant and
takes the longest to decay. This pole is called
the dominating pole.
当ξ>1时，这些极点在负实轴上，在-ξW
n的两边，瞬态响应为两个不同时间常数指数衰减
曲线之和。对应靠近原点的指数曲线具有大的时间常数
，并且衰减时间长。这样的极点称之
为主导极点。
Forξ=1, both poles
coincide at-Wn.
当ξ=1时，两个极点重合为：-Wn。
Forξ<1, the poles move along a circle of radius Wn
centered at the origin.
当ξ<1时，两个极点沿从原点为中心，Wn为半径的圆移动。