[1] Zhejiang Normal Univ, Dept Math, Jinhua 321004, Zhejiang, Peoples R China
[2] King Abdulaziz Univ, Dept Math, Jeddah 21589, Saudi Arabia
[3] Univ S Florida, Dept Math & Stat, Tampa, FL 33620 USA
[4] North West Univ, Dept Math Sci, Mat Sci Innovat & Modelling, Mafikeng Campus, ZA-2735 Mmabatho, South Africa
[5] Beijing Jiaotong Univ, Dept Math, Beijing 100044, Peoples R China
[6] Beijing Jiaotong Univ, Beijing Lab Natl Econ Secur Early Warning Engn, Beijing 100044, Peoples R China