1. School of Information Technology, Jiangxi University of Finance and Economics, Nanchang, Jiangxi, P. R. China
2. State Key Lab of Fire Science, University of Science & Technology of China, Hefei 230027, Anhui, P. R. China
3. School of Information Science and Technology, University of Science and Technology of China, Hefei 230027, Anhui, P. R. China