1. Electrical and Computer Engineering Management Department, North University of China, Shuozhou, Shanxi province, China
2. Department of Mathematics, Faculty of Education, Erciyes University, Melikgazi-Kayseri, Turkey
3. Department of Applied Mathematics, Faculty of Mathematical Sciences, University of Tabriz, Tabriz, Iran
4. Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI, USA