1. College of Textile Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, P. R. China;
2. Qinhuangdao Entry-exit Inspection & Quarantine Bureau Coal Inspection Technique Center, Qinhuangdao, Hebei, P. R. China;
3. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei, P. R. China