1. College of Mathematics and Systems Science & Institute of Mathematics and Physics, Xinjiang University, Urumqi 830046, China.
2. School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an 710049, China.
3. Corresponding author. College of Mathematics and System Science, Xinjiang University, Urumqi 830046, China, and School of Mathematics and Statistics, Xi’an Jiaotong University, Xi’an 710049, China.