This paper proposes a simple metric of path diversity dedicated for the type of end-to-end network.

End-to-end network is modeled as a directed acyclic graph,and then transformed into a segmented form.

Unified treatment of ultrasonic horn characteristics based on four-end network approach;

Based on the theory of four-end network, the resonant frequency of the composite stepped ultrasonic torsional-mode concentrator with a cone-like transited part, which depends on the geometrical dimensions of the tool rod attached to the concentrator, is studied by using electromechanical analogy method.

Discussion on Solving Linear Active Two-terminal Network Using Thevenin’s Theorem;

Several methods are presented for solving the equivalent resistance of the active two-terminal network,which is a difficut problem for students.

A two-terminal network is made up of the controlled source and voltage source and independence source is equal to a two-terminal network which is made up of a voltage source and a resistance.

Based on the transfer-matrix method,the general expressions of equivalent four-terminal network parameters of varying section torsional horn are derived,the relations between frequency equation and both the rotational velocity amplification and that of the surface tangential velocity of stepped type torsional ultrasonic horn with transitional section of cosine-like type are obtained.