Based on the equivalence principle and the reciprocity theorem, the multiple scattering up to Nth-order by N parallel 2-D targets arbitrarily located in a plane wave/Gaussian beam is considered.

A new equivalence principle of current control for shunt active power filters is introduced, which having no use for measurement of harmonic and reactive currents of nonlinear loads.

In accordance with Landau s thinking, on the basis of the principle of equivalence, from the gravitational field equation, we have rigorously reconsidered the concrete deductive process of the expression of energy-momentum pseudotensor of the pure gravitational field and the result is in good agreement .

Moreover, the wave-particle duality of the light and the"equivalent principle" of the Einstein Gravitation Field Theory were fUrther proved to be correct.

the equivalent of function is given and the equivalent principle of structure and function is put forward.

Equivalent stiffness equations in the normal and tangential direction at the bottom and walls of a semi-infinite elastic ditch were formulated by employing the principle of energy equivalence and Mindlin’s displacement equations in a semi-infinite elastic body subject to a concentrated force acting in the interior of the semi-infinite elastic body.

By introducing the electro magnetic flowmeter measurement into the homogeneous measurement system based on the passive field relationship in the space of magnetism and electron field,the similarity or equivalency between the solution Hall effect and electro magnetic flowmeter is presented, resulting in an equivalent measuring principle for both the Hall .