1. Center for General Education, China Medical University, Taichung, Taiwan
2. School of Science South West, University of Science and Technology, Mianyang, Sichuan, China
3. Center for Fundamental Science, and Research Center for Nonlinear Analysis and Optimization, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
4. Department of Mathematics, Chengdu University of Information Technology, Chengdu, Sichuan, China