1. College of Mathematics and Physics, China University of Geosciences, Wuhan, People's Republic of China
2. Faculty of Information Technology, Macau University of Science and Technology, Taipa, Macao, People's Republic of China
3. Department of Mathematics, Jinan University, Guangzhou, People's Republic of China
4. Colledge of Mathematics, Nanjing University of Posts and Telecommunications, Nanjing, People's Republic of China