Although the mixed pair of our country had ranked the eighth in 9th Aerobic Gymnastics World Championships, there still exists various gap with advanced countries in the areas such as move with difficulty, artistic design, the quality of the move.

The paper introduces three methods to measure the stabilization of short-term frequency:beating method,mixing two frequency method,timing the difference of frequency method,and the method to deal with the data,and on the base of beating method and timing the difference of frequency method,bringing a new method,to advance the precision.

The principle of operation of thyristor medium frequency equipment with double hybrid double frequency(DHDF) changer is described,The equ ipment is designed specially for the power supply of induction heating system.

The analysis on development trends of mixed doubles in all previons world Aerobics Championships;

This paper analyses the difficult actions of mix-double event in 9th Aerobic Gymnastics world championships by data investigation,observation log and data statistic.

This research analyses the final World Championship of mix-double Aerobics in 2004 and 2006 by data investigation,observation log and data statistic.