1. School of Mechanic al Engineering, Beijing Institute of Petrochemical Technology, No. 19 Qingyuan North Street, Huangcun Town, Daxing District, Beijing 102617, P. R. China
2. School of Information Engineering, Beijing Institute of Petrochemical Technology, No. 19 Qingyuan North Street, Huangcun Town, Daxing District, Beijing 102617, P. R. China