1. College of Surveying and Geo-Informatics, Shandong Jianzhu University, Jinan, China
2. College of Geodesy and Geomatics, Shandong University of Science and Technology, Qingdao, China
3. School of Physics, Peking University, Beijing, China
4. Jining Branch, Shandong Provincial Lunan Geology and Exploration Institute (Shandong Provincial Bureau of Geology and Mineral Resources No.2 Geological Brigade), Jining, China