Published on in Vol 8, No 12 (2020): December
                                    Preprints (earlier versions) of this paper are
                                    available at
                                    https://preprints.jmir.org/preprint/23357, first published
                                    .
                                

1 Harbin Institute of Technology, Shenzhen, China
2 Peng Cheng Laboratory, Shenzhen, China
3 Yidu Cloud Technology Company Limited, Beijing, China
