This paper comprehensively studies the properties of strength and toughness of U-shape steels 20MnK,Q275 on test pieces under various processes of intercritical hardening and self-tempering.

Simultaneous heating and quenching with high power medium frequency equipment for parts of long shaft,adopting special induction coil and adjustable induction coil and self tempering,will improve on medium frequency quenching quality of the parts and raise obviously productivity,thereby cause the enterprise to obtain fine product quality,high productivity and Low production cost.

The investigation was conducted on the technique of intercritical hardening by medium frequency induction and self tempering for the high strength bolts.

Fuzzy comprehensive evaluation on the spontaneous combustion in goaf and its application;

Study on spontaneous combustion in Gob of fully mechanized mining with top coal caving face;

Temperature measurement system for coal spontaneous combustion experiment;

The paper introduces the application of the thermometry for the research of spontaneous ignition in Jianxin Colliery,and makes a further study on the regularity of temperature change in the goaf behind the working face in the process of advancement,which has provided the scientific basis for the colliery against the spontaneous ignition.

In addition,the time series prediction model based on BP neural network was also set up by using of forecasting indexes of goaf spontaneous ignition.