Funding for this research was provided by:
National Key Research and Development Program of China (2016YFB1000104)
Huawei Technologies (not applicable)
Article History
Received: 1 November 2018
Accepted: 14 December 2018
First Online: 14 January 2019
Competing interests
: No conflict of interest exists in the submission of this manuscript. The manuscript is approved by all authors for publication.
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