This is an open access article licensed under the terms of the Creative Commons Attribution-Non-Commercial 4.0 International Public License (CC BY-NC 4.0)
(https://creativecommons.org/licenses/by-nc/4.0/legalcode), which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the
work is properly cited.
* Address correspondence to this author at the School of Geology Engineering
and Geomatics, Chang’an University, Xi’an, 710054, P.R. China; Tel:
+86 29 82339032; Fax: +86 29 82339042; E-mail: email@example.com