the Natural Science Foundation of China(Grant No.10471159,No.10171118);the key project of the Chinese Ministry of Education,Supported by Program for New Century Excellent Talents in University,Education Commission project Research Foundation of Chongqing(Grant No.K J060818,KJ060804);the Research Fund for the Doctoral Program of Chongqing Normal University(Grant No.06XLB023);the project supported by Chongqing Key Laboratory of Operations Research and System Engineering.
This work is supported by the Natural Science Foundation of China (Grant No.10471159,No.10171118);NCET,Education Commission project Research Foundation of Chongqing(Grant No.KJ060818,KJ060804)