Lichen Zhang Convergence Approach to Model Physical World and Cyber World of Aviation Cyber Physical System. 418-423 2014 DASC https://doi.org/10.1109/DASC.2014.81 https://doi.ieeecomputersociety.org/10.1109/DASC.2014.81 conf/dasc/2014 db/conf/dasc/dasc2014.html#Zhang14