由KVL和KCI u(x, t)=(roar)i(x, t)+(Lodx) di(x, t) du(x +(x,)+ at ax i(x,D)=G0x[(x,0)+ Ou(x, t) dx +Codx-u(r, t)+ Ou(x, t) di(, t) ai i+-dx +i(x,1)+ dx r,dxr Ndx Ox Cadx g.dx u+-dx x dxR dx 0 L dx 0 i x dx i i dx x  +  C dx 0 G dx 0 u u u dx x  +  0 0 ( , ) ( , ( , ) ( , ) ( ) ( , ) ( ) ) i u x t u x t x t u x t R dx dx i t L x x x d t   = + + +   0 0 ( , [ ( , ) ] [ ( , ) ( ] ) , ) u x t u x t , ( ) i x G u x t C u x t x dx dx dx x t d x t  = + +    +   ) ) ( , , i x t ( i x x t dx  + +  由KVL和KCL：