There is the danger that the high-speed connectivity of the Internet will reduce our attention span—that we will be incapable of reading anything of length or which requires deep concentration.

In this paper calculating method of lead angle of helical gear by measuring span length of length bar and base tangent length is put forward and lead angle calculating formula is deducel.

The calculation models of curved beam Bridges with same span length, but different curvature radius, center angles and supporting forms are established by means of finite element software.