Affiliation: | 1. School of Information Science and Engineering, Dalian Polytechnic University, Dalian 116034, PR China;2. School of Mathematical Sciences, Dalian University of Technology, Dalian 116024, PR China;3. Department of Mathematics, Bohai University, Jinzhou 121002, PR China;4. Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing 100190, PR China |