Based on a rational analysis of magnitude orders, the authors have obtained simplified equation systems at two levels, from which the fundamental pattern of the flow and its revision have been deduced smoothly; the damp effect of the vertical component of the magnetic field has been reasoned logically and the cause of the metal surface bump has been shown clearly.

This paper presents a basic law of the simplified equation of surface of degree 2, especially the law of the simplified equation of surface of degree 2 with two equal zero roots.

A planar simplified method for three-dimension cement-soil mixing piles composite foundation with FEM numerical analysis;

A simplified method for tooth surface equation of an equal-height spiral bevel gear;

Based on the differences of structural response between multi-dimensional excitation and simple-dimensional excitation,a simplified method to calculate member forces under multi-dimensional and multi-support excitation is presented in this paper.

According to the results,the simplification method is more conservative than the simulation method;the contact state between steel spiral case and its periphery concrete and the way of supporting of steel spiral case in construction have significant influences on the periphery concrete stress.