A major reason of making the gaps is the windthrow that is a factor of ecology turbulence, and it is a common disaster for wood productions, therefore , to study mechanism of windthrow is very important.

The major factors to affect windthrow contain the biologic mechanical attribute of tree, the mutual action of soil and base, disturbance of wind and so on.

It is an important approach to improve the control for end-point of LD converter, shorten the smelt times of steelmaking, decrease the smelt cost, improve the quality of molten steel, achieve the standardized operation for LD converter process and production planning by forecasting the first turning down.