1. School of Mathematics, China University of Mining and Technology, No. 1, Daxue Road, Xuzhou, Jiangsu Province, P. R. China
2. Lianyungang JARI Electronics Co., Ltd., No. 18, Shenghu Road, Lianyungang, Jiangsu Province, P. R. China
3. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Yuk Choi Road, Hung Hom, Kowloon, Hong Kong, P. R. China