By Analyzing the problems arising from the irrational selection of the overrun distance of tools in the process of internal circular exsecting in numerical control processing, the correct method of calculating too's overrun distance is proposed.

New technology of high-speed and ultra long haul fiber-optic communication system;

Discussion on gas emission law of coal mining face in seam with ultra closed distance to protective stratum;

Coverage of remote distance scene is a difficult problem in mobile network plan,the article introduces the characteristic of remote distance scene,analyses the maximum transmission distance of UMTS and transmission model over the sea,many coverage schemes for remote distance scene are also given.