A compressing method for the construction of quasi-cyclic LDPC(QC-LDPC)codes was proposed,which used a QC-LDPC code with large girth as mother code.

By selection of line slope,triangles are removed from the lattice,which leads to the girth of the point-line incident matrix no smaller than eight, the height of lattice is obtained by a searching algorithm,and the construction is simple and efficient.

A new method of measuring the stitch length of weft knitted fabric;

To enhance the reliability and automation of stitch length measurement,a stitch length measuring system through processing the scanned image based on MatLab was introduced.

This paper describes the testing methods for stitch length of weft knitting presently,including static measurement,dynamic measurement and association of static and dynamic measurement,and analyze the points of these methods.

Based on the knitting process of the jersey and 1+1 rib on an flat computerized knitting machine, the influences of the different parameters (yarn input tension, cam setting, machine running velocity and take down force) on the knittability of the glass fibre yarn, specially on the loop length and glass fibre damage, were analyzed.

The relations between the fibre damage degree and the loop lengths are also analysed.

Two testing methods for loop length of weft knitting which are usually used now are introduced firstly:static test method and dynamic method,the deficiency of which is pointed out;A new testing method is introduced in detail.

The technology improvement of long inner gear circle;

The construction of geodetic graphs containing the longest cycle C10 is studied.

The main work of this paper is on the longest cycle in connected claw-free graphs in order to know more about the construction of connected claw-free graphs.