The paper analyzes and compares the lumped parameters that are replaced the distributed parameters of actual cable for intrinsically safe explosion-proof test.

Aimed at the deficiency of multi-terminal transmission line fault location at present,combining with the fault location algorithm of transmission line which does not have branch,the author proposed the fault circuit identification method of T-connection transmission line,and solved the fault location with the lumped parameter circuit model and the distributed parameter circuit model.

Describes a frequency multiplier of step recovery diode with lumped parameter from tens MHz to hundreds MHz.

Based on the theory of the concentrated parameter, a three-dimensional dynamic model with 12 degrees of freedom for the spiral bevel gear transmission system was developed, where the flexional, torsional, axial and rotational motion were considered.

Based on the theory of the concentrated parameter,a three-dimensional dynamic(model) with multiple degrees of freedom for coupling vibration of a spiral bevel gear transmission system was developed,in which the flexional,torsional,axial and rotational motions were considered.

The concentrated parameter method and the movable boundary method are used to set up the simulation system of the once-t.

An S-band circulator featuring to be electrically quality,compact,and easily integrated is developed on the basis of the idea of semi-lumped parameters,and with the adoption of double Y junctions of inner conductor and the high field working mode.