1. Nonlinear Vibrations and Energy Harvesting Laboratory (NOVEHL), Department of Mechanical Engineering, Clemson University, Clemson, SC 29634
2. Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, NM 88003
3. Visiting Associate Professor Department of Mechanical and Materials Engineering, Masdar Institute of Science and Technology (MIST), Abu Dhabi, UAE e-mails: ;