1. School of Science, Xi’an University of Architecture and Technology, Xi’an, P. R. China
2. School of Mathematics and Information Science, Henan Polytechnic University, Jiaozuo, P. R. China
3. National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, 199 Ren-Ai Road, Suzhou, P. R. China
4. School of Civil Engineering, Xi’an University of Architecture & Technology, Xi’an 710055, P. R. China
5. School of Automation, Northwestern Polytechnical University, Xi’an, P. R. China
6. Math. Depart. Faculty of Science, Taif University, P. O. Box 11099, Taif 21944, Saudi Arabia
7. Mathematics Department, Faculty of Science, Zagazig University, Egypt