1. Department of Applied Mathematics, Yanshan University, Qinhuangdao 066004, China
2. Faculty of Economics and Management, Yanshan University, Qinhuangdao 066004, China
3. Department of Statistics, Yanshan University, Qinhuangdao 066004, China
4. Liren College, Yanshan University, Qinhuangdao 066004, China