1. George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
2. National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401, USA
3. School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, Arizona 85287, USA
4. School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA