【正文】 a set of constant parameter values ,as in the familiar RLC circuit ,the system is said to be stationary or timeinvariant or constant coefficient .當(dāng)所有的基礎(chǔ)方程都能用一組定常參數(shù)值來描述，正如熟知的RLC電路的情況，就稱該系統(tǒng)是穩(wěn)態(tài)的，或時(shí)不變的，或常系數(shù)的。//Finally ,if there are no external inputs and the system behavior is determined entirely by its initial conditions ,the system is said to be homogeneous or unforced . 最后，如果沒有外部輸入信號，系統(tǒng)的行為完全由自已的初始條件確定，該系統(tǒng)就稱為齊次或非強(qiáng)迫系統(tǒng)。3：In each case ,the input circuit of the amplifier can be represented by an equivalent passive impendence Zi defined as the ratio of Vi/Ii or admittance Yi ,defined as Ii/vi. 在每種情況下，放大器的輸入回路都可以用一個(gè)等值無源阻抗Zi（Zi 是vi與Ii的比值）or 等值導(dǎo)納Yi（Yi是Ii與Vi比值）來表示。5: In the process plant ,it is impractical to locate the control instruments out in the place near the process .在過程工廠中，將控制儀器安裝在室外靠近過程的地方是不現(xiàn)實(shí)的。7：It is assumed in each case that the forwardpath amplifier of a negative feedback system is unilateral ,so that signals can pass from input or output ,but not in the reverse direction from output to input ,and the only feedback path is through the network B。于是信號只能從輸入端到輸出端，而不能反方向傳遞。8：It is hoped that these will not only give the reader some familiarity with the process of modelbuilding but also satisfy him that linear differential equations are ,in fact ,reasonable models for a wide range of real systems .希望這些工作不單是使讀者熟悉模型建立的過程，而且也使大家確信，線性微分方程是各種實(shí)際系統(tǒng)的合理模型。10: It should be understood that any division of control engineering into “regulators ”,”servomechanisms” and “processcontrol systems” is very artificial and is really due to historic rather that logical reasons , A processcontrol systems is often a regular .我們應(yīng)該了解到:把控制工程分成調(diào)節(jié)器、伺服機(jī)構(gòu)與過程控制系統(tǒng)是由人為因素造成的，這是由于歷史上的原因而不是邏輯上的原因。//However ,a plicated processcontrol systems may possibly contain devices which could be defined as servomechanisms .The following are examples of control problems usually classified as process control。11：Its standard range is from 4 to 20mA DC for the current signal or from 1 to 5V DC for the voltage signal .其標(biāo)準(zhǔn)范圍對電流來說是420mA DC,對電壓力信號來說是15V DC。//Common measurement used in industry include flow rate, pressure , level, temperature ,analytical measurement (such as pH ,ORP and conductivity ),and many others particular to special ，壓力，物位，溫度，分析測量參數(shù)，如PH值，ORP 和電導(dǎo)率 ，以及許多其他特殊工業(yè)中的特殊參數(shù)。電樞電流產(chǎn)生的磁通使定子磁場畸變，所以產(chǎn)生了某些非線性，這叫做“電樞反應(yīng)”。3：Most classical control techniques were developed for linear constant coefficient systems with one input and one output (perhaps a few input and outputs) .大多數(shù)經(jīng)典控制技術(shù)都是帶有一個(gè)輸入、一個(gè)輸出（也可有數(shù)個(gè)輸入和輸出）的線性、常系數(shù)系統(tǒng)而發(fā)展起來的。//When nonlinearities and time variations are present ,the very basic for these classical techniques is removed .一旦出現(xiàn)非線性和時(shí)變性，經(jīng)典技術(shù)最根本的基礎(chǔ)就不復(fù)存在了。//However ,the greatest success has been limited to loworder systems . 然而經(jīng)典控制理論的最大成功也是局限于低階系統(tǒng)中。//It provides an ideal formulation for puter implementation and is responsible for much of the progress in optimization theory .它也為計(jì)算機(jī)處理提供了一種理想的表示方法，并引起了許多方面最優(yōu)化理論的進(jìn)展。因此，對線性電路性能和線性電路分析的研究就具有理論和實(shí)踐的雙重意義。2: Negative feedback occurs when a portion of the output signal of an amplifier is fed back and subtracted from the input signal, causing a reduction in the effective input signal. 所謂負(fù)反饋是指輸出信號的一部分被送回輸入端，與輸入信號相減，從而削弱了有效輸入信號，//The most important effect of this is to make the overall amplifier gain almost immune to changes in the amplifier unit gain, and dependent almost entirely on the feedback network ，其總增益的大小完全取決于反饋網(wǎng)絡(luò)的元件參數(shù)。O: 1：One additional distinction not shown in could be made between largescale system and smallscale system . 。 //These differences have motivated different methods of approach . 這些差別已經(jīng)促進(jìn)了不同的方法的發(fā)展。2：One of the conductors is mon to both sides of the bridge while the other two connect one to each side of the bridge . 三導(dǎo)線中，其中一根對電橋兩臂是相同的，而其它兩根連在電橋的兩臂上。3：Operational amplifiers with very high gains are readily available , making the application of negative feedback on a large scale practical and inexpensive. 高增益的運(yùn)算放大器是容易得到的，這便使負(fù)反饋的使用現(xiàn)實(shí)而經(jīng)濟(jì)。S: 1：Several factors provided the stimulus for the development of modern control theory :(1)The necessity of dealing with more realistic models of systems .(2)The shift in emphasis towards optimal control and optimal system design .(3)The continuing developments in digital puter technology .(4)The shortings of previous approaches .(5)A recognition of the applicability of wellknow methods in other fields of knowledge .有幾個(gè)因素激勵(lì)了現(xiàn)代控制理論的發(fā)展：(1)處理更加真實(shí)的系統(tǒng)模型的必要性.(2)研究重點(diǎn)朝向最優(yōu)控制和最有系統(tǒng)設(shè)計(jì)的轉(zhuǎn)移.(3)數(shù)字計(jì)算機(jī)技術(shù)的不斷發(fā)展 (4)原有方法的短缺.(5)對于將熟知方法在其它知識(shí)領(lǐng)域中應(yīng)用的廣泛認(rèn)同2．Should there be an unpensated variation in the reference junction temperature ,there will be a corresponding change in millivolt with a resultant error in tempe