Institution: | 1. Department of Applied Mathematics, Nanjing University of Science and Technology, Nanjing 210094, PR China;2. School of Mathematical Sciences, Ocean University of China, Qingdao 266100, PR China;3. Department of Mathematics and Statistics, University of Minnesota Duluth, Duluth, MN 55812, USA;4. Department of Mathematics, Nanjing University, Nanjing 210093, PR China |