Affiliation: | 1. Department of Applied Mathematics , South China Agricultural University , Guangzhou 510642, P.R. China;2. School of Mathematics and Computational Science , Sun Yat-Sen University , Guangzhou 510275, P.R. China tsiuhua@scau.edu.cn;4. School of Mathematical Sciences , South China Normal University , Guangzhou 510631, P.R. China;5. School of Mathematics and Computational Science , Sun Yat-Sen University , Guangzhou 510275, P.R. China |