Qingdao University of Technology, Qingdao University of Technology, Qingdao University of Technology, Qingdao University of Technology, Qingdao University of Technology, Qingdao University of Technology, affiliation not provided to SSRN, affiliation not provided to SSRN, Qingdao University of Technology, Qingdao University of Technology and Qingdao University of Technology