This paper introduced the structure characteristics of combined piercing unit and combined punching angle unit in detail, and elaborated the application scope and the maintenance management of the combined punching unit.

In order to simplify the work of pre-process in finite element analysis of large scale bolted rock discontinuities,a combined element model of bolted rock discontinuities is presented based on the displacement interpolation function of discontinuity element and the stiffness matrix of bolt element.

Since pre-stressed concrete box girders usually have a large number of curve pre-stressed tendons,a type of combined element is presented to simulate the prestressed tendons of box girders,and then the number of elements can be significantly reduced.

Through contrastive analysis of calculated value and test data, it is proven feasible and correct to use composite element and externally prestressed element together to analyze externally prestressed concrete structure, while providing support and experience to the numerical simulation in bridge structure.

To analyze the performance of reinforced concrete structures numerically, the composite element is developed, which inherits and expands the features of the original isoparametric element, and can consider contributions of concrete and steel to the element stiffness separately.

Based on the composite element,3D model of concrete creep is created firstly.

A new kind of PWM control circuit module of the cell cascaded multilevel inverter which is based on the CPLD is explored,in allusion to the blank actuality of special purpose PWM control IC which the multilevel inverter is faced with at the present time.

A combined beam model representing the periodicity of the microstructure and micro deformation of 3D woven composites is developed for predicting mechanical properties.