1. School of Mathematics, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, P. R. China
2. Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles (NUAA), MIIT, Nanjing 211106, P. R. China
3. School of Mathematical Science, Heilongjiang University, Harbin 150080, P. R. China