This simple circuit made up of a source,a load and two wires is seldom,if ever,met with in practice.Practical circuits may contain a large number of sources and loads interconnected in a variety of ways. 这种由一个电源、一个负载和两根导线组成组成的简单电路，在实践中即使能碰到碰到也是很少见的。 实际电路可能包括许多按不同方式连接连接的电源和负载。 The direction of current flow may be shown either by a hollow arrowhead or by supplying the current symbol with a double subscript whose first digit identifies the junction at a higher potential and the second (省略了 identifies) the junction at a lower potential. 电流的方向既既可用一个空心箭头来表示，又又可用带有双下标双下标的电流符号来表示，且第一个下标 认定为高电位点，第二个下标为低电位点。 In a potential-distribution diagram it is represented(on a suitable scale)by the slope of the respective curve at any point,the slope being defined as the tangent of the angle that the line tangent to the curve at that point make with the x-axis. 在电势分布图中，电流由曲线上该点相应的斜率斜率表示，斜率定义为切线与切线与 x 坐标轴夹角的正切坐标轴夹角的正切。It follow that the r.m.s.(effective) value of an alternating current is numerically equal to the magnitude of the steady direct current that would produce the same heating effect in the same resistance and over the same period of time. 由此得出：交流电流的均方根（有效值）大小上等于在相同电阻上和同一时间内产生相同的热 效应的恒稳直流电流。 The operational voltage amplifier is represented schematically by the triangular symbol .A0 is the voltage gain from differential input to single-endrd output and is always a positive number . Phase reversals are taken into account at the input terminal，which is the reason why these are labeled”+” and”-”. The voltage at each terminal ，including the output ,may be referred to common reference ,usually ground ,and unless otherwise stated ,this common reference will be assumed. Thus ,letting V(+) represent the voltage of the positive input terminal with respect to the common reference ,and V(-),that of the negative input terminal ,we may define the differential input voltage as ,and the output voltage is .)()(VVVididVAV00电压运算放大器可用三角形符号来表示。A0 表示从差动输入端到单一输出端的电压增益，并 恒为正值。考虑到在输入端可能会有反相输入的情况，所以要标上“+”号与“-”号。每个端口包 括端口的输出端口的电压，都可以选一个共同的参考点，通常选大地，除非另有说明，否则所 假定的参考点就是地。这样，用 V(+)代表正向输入端对参考点的电压，而 V(-)则代表负向输入端对参考点的电压，我们可以将差动输入电压定义为，输出电 aa 压)()(VVVid。idVAV00The significance of this result is that the terminal voltage gain ,which is the usable voltage gain , is independent of the parameters of the amplifier ,and depends only on the external component R1 and 这个结论的意义在于端电压增益（这是很有用的电压增益）与放大器的参数无关，而只取决于 外部元件 R1 和 R2。 A truth table is a list of all of the possible input variable state combinations of a circuit listed in binary-sequential order with the corresponding output state for each combination listed in an adjacent column.Table1 shows the binary numbers corresponding to the decimal numbers from zero to fifteen. 真值表是这样的一个表格，电路中可能输入的所有不同状态组合组合按二进制顺序连续排列，输出 状态与输入端的每种组合一一对应与输入端的每种组合一一对应，表 1 表示了与十进制 015 一一对应一一对应的二进制数。 The truth table is used as the beginning point in designing or analyzing a logic circuit .The sequential listing makes it easy to recognize if any input combinations were missed. It is made up of either from the problem specifications or by sequential testing of an assembled circuit. A logic equation can be formulated from the truth table and a logic circuit can be developed from the equation. Truth tables are used in defining the basic AND,OR and NOT functions below 在设计或分析一个逻辑电路时，首先要列写真值表。这种连续的表格很容易辨认出这种连续的表格很容易辨认出是否遗漏了 任何一种组合，她可有问题的具体情况或对一集成电路进行连续测试来建立。由真值表可建立 逻辑等式，由此等式就可构造一逻辑电路。在下面定义基本逻辑“与”、 “或”和“非”的函数中就 用到了真值表。 The logic AND function can be expanded to any number of inputs ,simply by applyingthe basic definition.Thus a 5-input logic AND gate will produce an output only if the input combination ABCDE=11111 exists,and providing the physical circuit will still function properly with that many input attached. 只要运用基本定义，逻辑与函数便可扩展到任意一个输入。因此一个五输入的逻辑与门只有在 ABCDE=11111 且具体电路与那些连接的输入量有恰当的函数关系时才等于一。 Today motion control is an area of technology that embraces many diverse disciplines,such as electrical machines,power semiconductor devices, converter circuits,dedicated hardware signal electronics,control theory,and microcomputers,more recently,the advent of VLSI/ULSI circuits and sophisticated computer-aided design techniques has added new dimensions to the technology. 当今世界的运动控制是这么一个综合性的技术领域，其包括诸如电机、电力半导体装置、转换 器电路、专门的硬件信号电子学、控制理论、微型计算机等方方面面的众多技术领域。最近出 现的超大规模集成电路，甚至特大规模集成电路，再加上日渐程序的计算机辅助设计技术出现， 又进一步拓宽了运动控制技术领域新的运用范围。 Mechanical motion control systems found widespread acceptance in industry since the invention of the steam engine started the first industrial revolution in eighteenth century,when mass industry manufacturing replaced manual labor. 18 世纪蒸汽机的发明开启了第一次工业革命，当时大规模的工业生产化代替了手工劳动，从 此以后，运动机械的运动控制系统便在工业领域得到广泛地应用。 The concept of computer-integrated manufacturing(CIM),in which business decisions are translated to designs, which are then translated to manufacturing through a hierarchy of computers and motion control systems, will become a reality in the near future. 计算机集成制造的概念，将在不远的将来成为现实，所谓计算机集成制造，就是首先将商务决 策