[Li Xin;Hu Zhi] Nanhua Univ, Sch Mech Engineer, Hengyang, Hunan, Peoples R China.^[Zhang Chun-liang] Guangzhou Univ, Sch Mech & Elect Engineer, Guangzhou, Guangdong, Peoples R China.^[Li Li-jun] Ctr South Univ Forestry & Technol, Sch Mech Engineer, Changsha, Hunan, Peoples R China.