Funding for this research was provided by:
National Natural Science Foundation of China (61801249)
Nantong University-Nantong Joint Research Center for Intelligent Information Technology (KFKT2016B01, KFKT2017B01)
the open research fund of National Mobile Communications Research Laboratory, Southeast University (No. 2015D02)
Nantong Vocational University (18ZK01)
Text and Data Mining valid from 2019-03-18
Received: 19 October 2018
Accepted: 21 February 2019
First Online: 18 March 2019
: The authors declare that they have no competing interests.
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