1.Department of Mathematics and Physics,Hefei University,Hefei 230601,China 2.School of Computer & Information,Hefei University of Technology,Hefei 230009,China 3.Department of Mathematics and Physics,Bengbu College,Bengbu,Anhui 233000,China 4.School of Mathematics and Information Science,Shaoguan University,Shaoguan,Guangdong 512005,China