1. School of Mathematics and Physics, China University of Geosciences, Wuhan, 430074, P. R. China
2. Data Recovery Key Laboratory of Sichuan Province, College of Mathematics and Information Science, Neijiang Normal University, Neijiang 641100, P. R. China
3. Mathematical Institute, Oxford University, Oxford, OX2 6GG, UK
4. School of Mathematics and Statistic, Northwestern Polytechnical University, Shannxi, 710072 Xi’an, P. R. China