We define transfer function H(s) as a ratio of the Laplace transform of system output (or response)(s) to the Laplace transform of the input(or forcing function)v(s) when all initial conditions are zero, then

the short-circuit input impedance I12=0 the short-circuit forward current gain I1V2=0 Let 1=0 he open-circuit reverse voltage gain I1=0 the open-circuit output admittance

Three-phase sources have three Q terminals called the line terminals(a, b,c). + Neutral connection--n an b+V n bn Balanced three-phase sources may

Example 1: If 0=4v2 cos\tV, Z=2/600Q2 Find p(t)and P. Solution:

The forced response The steady state responseThe(t) has been switched into the circuit at some remote U.=V. cos ot time in the past, and the natural response has died-out completely. The forced response(steady state response)must satisfy the differential equation

The Normal Distribution: the distribution of a continuous r.v. whose value depends on a number of factors, yet no single factor dominates the other. 1. Properties of the normal distribution: 1)The normal distribution curve is symmetrical around its mean valueu. 2)The PDF of the distribution is the highest at its mean value but tails off at its extremities

习题14-2 解:(1)由x=0.1cos20t+与x=Acos(t+)比较得振幅A=0.1(m)角频率=20初相π频率V==10周期T==0.1(s)

一、热力学(thermodynamics)的研究对象与研究方法 物态(state of matter):物质存在的物理状态 物质主要存在三种基本物理状态:固态、液态 和气态 热学是研究一切物态的热现象的学科,我们这里主 要研究气态,但有时也会牵涉到固态和液态。 从宏观上看,热学研究物体的宏观热现象:与温度有 关的物态的物理性质的变化。由观察和实验来总结热 现象的规律,得出热现象的宏观理论,这部分称为热 力学。 热力学利用宏观上可观测的物理量,如:,V,T 来研究热现象的规律

1.名词(substantivum)(简称 subst.或s.)表示人,地,事物的名称。变格。 2.形容词(adiectivum)(简称a)表示人和事物的特征。词尾的变化随名词走。变格 3.动词(verbum)(简称v)表示人或事物的动作或状态。变格。植物学中一般不用,故省略

In addition to the equations of linear impulse and momentum considered in the previous lecture, there is a parallel set of equations that relate the angular impulse and momentum. Angular Momentum We consider a particle of mass, m, with velocity v, moving under the influence of a force F. The angular momentum about point O is defined as the \moment\ of the particle's linear