School of Computer, National University of Deference Technology, Changsha, PR China. ljwnudt@163.com|School of Computer, National University of Deference Technology, Changsha, PR China. ljwnudt@163.com|School of Computer, National University of Deference Technology, Changsha, PR China. ljwnudt@163.com|School of Computer, National University of Deference Technology, Changsha, PR China. ljwnudt@163.com