1. Department of Mechanical Engineering, Stanford University, Stanford, California 94305, USA
2. Department of Mechanical Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 17104, South Korea
3. Element Six Technologies, Santa Clara, California 95054, USA
4. Raytheon Company, Andover, Massachusetts 02451, USA