1. Department of Mathematics and Computer Science, Tongling University, Tongling, Anhui, China
2. Department of Mathematics, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan
3. Department of Aerospace Engineering, Faculty of Engineering, Universiti Putra Malaysia, Seri Kembangan, Malaysia
4. School of Mathematics and Physics, Anhui Jianzhu University, Hefei 230601, China