1. School of Mathematical Sciences, University of Science and Technology of China, Hefei, Anhui, China
2. The Wm Michael Barnes '64 Department of Industrial and Systems Engineering, Texas A&M University, College Station, TX, USA
3. The Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN, USA
4. The Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MN, USA