1. LAB2701 1 , Atwood, Oklahoma 74827, USA
2. Department of Mechanical and Aerospace Engineering, North Carolina State University 2 , Raleigh, North Carolina 27695, USA
3. Department of Electrical and Computer Engineering, Auburn University 3 , Auburn, Alabama 36849, USA
4. Department of Electrical and Computer Engineering, University of Alabama in Huntsville 4 , Huntsville, Alabama 35899, USA