1. Department of Mathematical Sciences, College of Science, UAE University, P.O. Box 15551, Al-Ain, UAE
2. Department of Mathematics, Faculty of Sciences, Yuzuncu Yil University, Van, Turkey
3. Mathematics Department, Faculty of Science, Mansoura University, Mansoura, Egypt
4. Research Center for Wind Energy Systems, Kunsan National University, Gunsan-si 54150, Republic of Korea
5. Department of Mathematics, Bharathiar University, Coimbatore, Tamil Nadu 641 046, India