Submitted on: 22 December 2012.
Revised on: 18 April 2013.
Accepted on: 21 May 2013.
___________________Computer Science Review---ELSEVIER
http://reply.papertrans.cn/1/63/6254/6254-32.png
http://reply.papertrans.cn/1/63/6254/6254-33.png
http://reply.papertrans.cn/1/63/6254/6254-34.png
http://reply.papertrans.cn/1/63/6254/6254-35.png
http://reply.papertrans.cn/1/63/6254/6254-36.png