1. School of Information Science and Technology, Yunnan Normal University, Kunming 650500, China
2. Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore, Pakistan
3. Abdus Salam School of Mathematical Sciences, Government College University, Lahore, Pakistan
4. Department of Applied Mathematics, Iran University of Science and Technology, Narmak, Tehran, Iran
5. Department of Mathematics and Computer Science, Adelphi University, Garden City, NY 11530, USA
6. School of Mathematics and Physics, Anhui Jianzhu University, Hefei 230601, China