Funding for this research was provided by:
National Natural Science Foundation of China (61771150)
Natural Science Foundation of Hunan Province (2015JJ2016)
Projects of Guangxi Key Research (AB17129028)
Guangxi Colleges and Universities Key Laboratory of Satellite Navigation and Position Sensing
Youth Talent Support Plan and Scientific Research Foundation of Changsha University (SF1615)
Text and Data Mining valid from 2019-05-03
Received: 10 December 2018
Accepted: 18 April 2019
First Online: 3 May 2019
: The authors declare that they have no competing interests.
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