S S symmetry Article A Novel Quality Defects Diagnosis Method for the Manufacturing Process of Large Equipment Based on Product Gene Theory Wenxiang Xu 1,2, Chen Guo 3,*, Shunsheng Guo 1,2 and Xixing Li 4 1 School of Mechanical and Electronic Engineering, Wuhan University of Technology, Wuhan 430070, China; xuwenxiang910327@126 …