“…After the transformation, the relevant frequency components could be revealed by spectrum analysis methods. Researchers at various universities, such as The University of New South Wales [46] , [47] , [48] , [49] , University of Lyon [50], [51], [52], Beijing Jiaotong University [53], [54], [55], [56], Xi'an Jiaotong University [57], [58], [59], [60] , Beijing University of Technology [45] , [61] , [62] , and University of Ottawa [63], [64], [65], have contributed a lot to this topic.…”