1. School of Geomatic and Environmental Engineering, Henan Polytechnic Institute, Nanyang 473000, P. R. China
2. School of Automation Engineering, Henan Polytechnic Institute, Nanyang 473000, P. R. China
3. School of Chemistry, South China Normal University, Guangzhou 510006, P. R. China
4. Department of Physics, School of Science, Harbin University of Science and Technology, Harbin 150080, P. R. China
5. College of Material Science and Engineering, Key Laboratory of Advanced Structural Materials, Ministry of Education, Changchun University of Technology, Changchun 130012, P. R. China