The electromotive force equations of salient pole synchronous motor are deduced by two-reaction theory and by coupling circuit concept.

In the interest of realizing carrier communication using LVPL, it is sticking point to analyse and design the coupling circuit of the communication.

By the use of analogy relation in electromechanical system,the mechanical system is converted into the equivalence electrical circuit,finally,electromechanical coupling circuits of rotating machines are deduced.

Using a new quantization idea of the damped electric circuit, the inductive-coupled electric circuit is quantized when there exist resistances in the component circuits.

The effects of the difference of circuit parameters or capacitances and inductances on the quantum fluctuations in the non-resonant damped mesoscopic coupled electric circuits were studied.

For different states of the mesoscopic capacitive coupled electric circuit, reduction of quantum fluctuations induced by the coupling was studied.

Starting with the equation for the classical motion of nondissipative mesoscopic mutual inductance coupled circuits, we studied the quantization scheme of the coupled circuits and the quantum fluctuation of the voltage and current in the eigenstate of the coupled circuits.