1. Faculty of Information Engineering and Automation, Kunming University of Science and Technology , Kunming 650050, P.R. China
2. Department of Computing Sciences, The College at Brockport, State University of New York , Brockport, NY 14422, USA
3. School of Computer Science and Engineering, Central South University , Changsha 410083, P.R. China
4. Hunan Provincial Key Lab on Bioinformatics, Central South University , Changsha 410083, P. R. China