If reciprocity and symmetry exist for passive two port networks of linear time invariant under zero intial condition,the circuit parameters will have some important characters.

Basing on traditional operator theory,operator madel for a circuit is established,and a new method for the solution of response of linear time invariance system is introduced.

The application of Non-linearity theory in architectural design;

Generalized Boolean Functions with Perfect Nonlinearity;

A case study on the factors of oasis-desert ecosystem evolution and its non-linear relationship in Xinjiang;

Design and analysis of linear photo-electric isolating amplifier circuit with single power supply and full output;

The linear application of photoelectric coupler in medical instruments;