1. Department of Electrical Engineering and Computer Science, University of California Irvine, Irvine, California 92697, USA
2. National Research Council–AMRDEC, Charles M. Bowden Research Laboratory, Redstone Arsenal, Alabama 35898, USA
3. Charles M. Bowden Research Laboratory, AMRDEC, U.S. Army RDECOM, Redstone Arsenal, Alabama 35898, USA