Funding for this research was provided by:
the Shanghai Municipal Natural Science Foundation (17ZR1445500)
the State Key Laboratory of Rail Traffic Control and Safety (RCS2018K010)
the Humanities and Social Science Research Project (15YJCZH148)
Article History
Received: 2 October 2017
Accepted: 5 April 2018
First Online: 15 June 2018
Competing interests
: The authors declare that they have no competing interests.
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