Funding for this research was provided by:
National Natural Science Foundation of China (61672092)
Foundation of Science and Technology on Information Assurance Laboratory (No.614200103011711)
Fundamental Research Funds for the Central Universities (No.2017RC016, 2018JBZ103)
Beijing Excellent Talent Training Project (No.BMK2017B02-2)
Text and Data Mining valid from 2019-03-29
Received: 31 October 2018
Accepted: 12 February 2019
First Online: 29 March 2019
: The authors declare that they have no competing interests.
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