In this paper the matrix expressions of equivalent points of microcosmic symmetrygroups of crystal unit spaces and their corresponding reciprocal spaces are applied in the dis-cussion of the systematic absence law of the crystal s X-ray diffraction.

Based on Xray powder diffraction data for the rare earth compound DyNiSn, the LAZY PULVERIX program was used in determining the equivalent point positions of atoms Dy、Ni、Sn in cell.

The equivalent circuit with no coupling of T coupled inductors;

Analysis of the equivalent capacitive property about dcmotor;

Equivalent damage value transform according to extrema of shear stress time history and its application in earth and rockfill dam s response to multi-point earthquake input;