By making use of the computer,we determine upper bounds for the number of orientation- reversing free actions of finite groups on closed orientable surfaces T~(nr+1)and all finite groups which act orientation-reversing freely on closed orientable surfaces T(nr+1)with low genus or T~p such that p-1 is a prime.

In the first chapter, we mainly discuss free actions on closed orientable surfaces by finite groups.

A new 4-node C~0 quadrilateral plate/shell element with drilling degree of freedom;

Quasi-conforming triangle plate and shell elements with drilling degree of freedom;

Based on the original Allman s element with drilling degree of freedom and the drilling degree definition, a modified element is presented by means of perfecting the variational functional Πp of Allman s element in the paper.

High calculation precision result can be obtained in finite element analysis of shear wall by using rectangular finite element method,however,for analysis of special structure like staggered shear wall,the introduction of rotational degree of freedom in rectangular element will be more suitable.

It introduces the concept on the rotational degree of freedom of the continuous mechanics.

A rectangular membrane element with rotational degree of freedom is constructed through finite belts of unit length and width.