12.1同时打开多个数据库文件 12.2调用非当前库文件数据联访 12.3被访工作区记录指针的自动移动关联 12.4直接用一个非当前库文件修改当前库文件命令— UPDATE 12.5数据库文件的连接jON

一、Linux文件系统概述 二、文件系统的使用方法 三、文件系统的创建 四、挂装和卸装文件系统 五、常用的文件系统维护命令 六、自动挂装文件系统 七、磁盘限额 八、交换空间

一、自发辐射受激辐射 1自发辐射 原子在没有外界干预的情况下,电子会由处于激发态的高能级E2自动跃迁到低能级E1,这种跃迁称为自发跃迁.由自发跃迁而引起的光辐射称为自发辐射

1 For the circuit given in Fig. 18-14, the R C2, fc are given find the switched capacitor equivalent

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:

I Consider the graph shown in Fig. 15-15. Denote the tree made up of b 6, bs, and b, by t (a)Find all the fundamental loops of this graph corresponding to T (b) Find all the fundamental cutsets of this graph corresponding to t (c) Write the incidence matrix of this graph choose n 4 as the datum

sequence. The balanced source supplies IMW and 0.2M VAR. If R, =12, find: (a) the line current;(b)Zp; ()the transmission efficiency

Find the four Y parameters of the network shown in Fig

Let vs=100 cos a t V in the circuit shown in Fig. 9-12.(a) Find the equivalent parallel RLC circuit and then determine resonant frequency @r, Q, and v(t).(b) Find i, (t),i2(t), and i3(t) (c)Calculate the average power loss in the 10 kQ2 resistor and the maximum energy stored in the inductor

(a)Find V, in Fig. 8-20.(b)To what identical value should each of the 4Q2 resistors be changed so that V2 is 180 out of phase with the source voltage?