1. a Department of Mechanical and Electrical Engineering , College of Mechanical and Electrical Engineering, North University of China , Taiyuan , 030051 , P.R. China
2. b Department of Materials Science and Engineering , School of Material, Northwestern Polytechnical University , Xi’an , 710072 , P.R. China
3. c Department of Mechanical Engineering , University of Akron , Akron , 44325 , OH , USA