This work was supported in part by the National Natural Science Foundation of China under Grant 51979015, Grant 51879015, and Grant 51809021, in part by the Natural Science Foundation of Hunan Province, China, under Grant 2018JJ3535, and in part by the Transportation Science and Technology Foundation of Qinghai Province under Grant 2014-09. The work of Bin Deng was supported in part by the China Scholarship Council.