1. School of Mechanical Engineering Xi'an Jiaotong University Xi'an 710049 P. R. China
2. Department of Critical Care Medicine The First Affiliated Hospital of Harbin Medical University Harbin 150001 P. R. China
3. State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information School of Electronic Science and Engineering Xi'an Jiaotong University Xi'an 710049 P. R. China
4. School of Electrical and Electronic Engineering Nanyang Technological University 50 Nanyang Avenue Singapore 639798 Singapore