Authors
Kaijun Wang
School of Mathematics and Computer Science, Fujian Normal University, Fuzhou 350007, P. R. China
Baijie Wang
School of Computer Science and Technology, Xidian University, Xian 710071, P. R. China.
Liuqing Peng
School of Computer Science and Technology, Xidian University, Xian 710071, P. R. China.
