1. State Key Laboratory for Strength and Vibration of Mechanical StructuresInternational Center for Applied MechanicsDepartment of Engineering MechanicsXi'an Jiaotong University Xi'an 710049 China
2. The George W. Woodruff School of Mechanical EngineeringGeorgia Institute of Technology Atlanta GA 30332 USA
3. School of Engineering and Applied ScienceKavli Institute for Bionano Science and TechnologyHarvard University Cambridge MA 02138 USA