ZHENG Chang-bo1, LI Xiao-yi2, CHOU Wan-xi3
(1. Vocational and Technical College,Dalian Ocean Univ,Dalian, Liaoning 116300,China; 2. School of Mathematics and Systems Science, Shenyang Normal Univ, Shenyang, Liaoning 110034, China; 3. School of Civil Engineering and Architecture, Anhui Univ of Science and Technology, Huainan, Anhui 232001, China)