Funding for this research was provided by:
Civil Aviation University of China (3122018D032, MHRD20160106)
Article History
First Online: 25 March 2019
Compliance with ethical standards
:
: Author Chunxiao Zhang declares that she has no conflict of interest. Author Qiang Li declares that he has no conflict of interest. Author Yankuan Liu declares that he has no conflict of interest.
: This article does not contain any studies with human participants or animals performed by any of the authors.
: Informed consent was obtained from all individual participants included in the study.