Published on in Vol 8, No 5 (2020): May
                                    Preprints (earlier versions) of this paper are
                                    available at
                                    https://preprints.jmir.org/preprint/18664, first published
                                    .
                                

1 School of Computer and Information Technology, Shanxi University, Taiyuan, China
2 Complex Systems Research Center, Shanxi University, Taiyuan, China
3 College of Mathematics, Shanxi University of Technology, Taiyuan, China
