1. School of Electronic and Information Engineering, University of Science and Technology Liaoning, Anshan, Liaoning, People's Republic of China
2. Faculty of Engineering, Lakehead University, Thunder Bay, ON, Canada
3. Department of Mathematics, Bohai University, Jinzhou, Liaoning, People's Republic of China
4. School of Science, University of Science and Technology Liaoning, Anshan, Liaoning, People's Republic of China