1. School of Math and Information Science, Guangzhou University, Guangzhou 510006, China
2. Key Laboratory of Mathematics and Interdisciplinary Sciences of Guangdong Higher Education Institutes, Guangzhou University, Guangzhou 510006, China
3. Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215, USA
4. School of Cyberspace Security, Beijing University of Posts and Telecommunications, Beijing 100876, China
5. School of Management, Northwestern Polytechnical University, Xian 710072, China