1. Department of Information and Statistics, Guangxi University of Finance and Economics , Nanning , Guangxi 530003 , People’s Republic of China
2. Department of Mathematics, College of Education, University of Sulaimani , Sulaimani , Kurdistan Region , Iraq
3. Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology , Shanghai 200237 , China