1. Faculty of Engineering, Anhui Sanlian University, Hefei 230601, China
2. Department of Computing, Mathematics and Electronics, “1 Decembrie 1918” University of Alba Iulia, 510009 Alba Iulia, Romania
3. Department of Mathematics and Statistics, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia
4. Department of Mathematics, Technical University of Cluj-Napoca, 400114 Cluj-Napoca, Romania
5. General Education Department, Anhui Xinhua University, Hefei 230088, China