Institution: | 1. College of Sciences, North China University of Technology, Beijing 100144, PR China;2. KLMM, Academy of Mathematics and Systems Science, Chinese Academy of Sciences, Beijing, 100080, PR China;3. School of Mathematical Sciences and Physics, North China Electric Power University, Beijing, 102206, PR China;4. School of Mathematical Sciences, Graduate University of Chinese Academy of Sciences, Beijing, 100049, PR China |