一、例题精解 【例题20.1】单相桥式可控整流电路如图20.1所示,已知R=20Q,要求U在0-60V 的范围内连续可调。(1)估算变压器副边电压值U2(考虑电源电压的10%波动); (2)求晶闸管控制角a的变化范围;(3)如果不用变压器,直接将整流电路的输入 端接在220V的交流电源上,要使U仍在060V范围内变化,问晶闸管的控制角a又将 怎样变化?

Consumption over the Life Cycle You are currently 35 years old, expect to retire in 30 years at age 65, and then to live for 15 more years until age 80 u You current income is $30,000 per year, and you real labor income adjusted for inflation remains at $30,000 per year until age 65 u The real rate of interest is 3% per year u Assume you plan to consume a constant stream of the same amount in each of the next 45 years, denoted by

一、填空(20分) 1.热力学第一定律可以写成△U=Q-W和△U=Q+W,产生这种差别的原因是对于有理想气体参与的化学反应,则△H△U(填“>”、“=”或“<

1 At a frequency of 796 Hz, compute Zo,u and for a line having the following parameters: F2230 u H/km,=0.0055 u F, r-6./km, g negligible. 2 At certain frequency, transmission line has Zo=5560°andy=0.005+j0.03np/km The line is 60 km long. A sinusoidal voltage of 100V at the specified frequency is applied to one end. Find:

1、试推导出图 4.1 的静态输出表达式和相应的 K 值，画出输入/输出曲线。 2、一应变电阻 R=120Ω，K=2，用作 800μm/m 的传感器元件，求ΔR， ΔR/R。若用电桥测量电路，U=4V，求相应的输出 U0。 如应变片所受应力减少，使相应的输出 U0 降至 1mV，求此时的应变值

为了对论域U={1,2…,n}中的元素进行 排序,由m个专家组成专家小组M,分别对U中的元 素排序,得到m种意见: ={, \2, ..} 其中v是第i种意见序列,即U中的元素的某一个 排序

一、链式法则 定理 如果函数u = φ(t)及v =ψ (t)都在点t 可导，函数z = f (u,v)在对应点(u,v)具有连续偏导数，则复合函数z = f [φ(t),ψ (t)]在对应点t可导，且其导数可用下列公式计算：

Goal: Maintain a dynamic subset S of size n of the universe U = {0, 1, …, u – 1} of size u subject to these operations:

第一题: 1.y(t)=u(t-t) 使用拉式变换的定义: Y(s)=\u(t-r) 令T=t-T, Y(s)=Se-ru()= u()dt=(s) 所以,G(s)=ex

10-5 已知U2=20 UO(AV)=0.9U2=0.9×20＝18V IO(AV)= UO(AV)/ RL=18/1=18mA ID(AV)= IO(AV)/2=18/2=9mA URM = 2U2 = 1.41 20 = 28.2V