1. Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 W. Green Street Urbana IL 61801-2906 USA
2. Department of Mechanical Engineering University of Maine 5711 Boardman Hall Orono ME 04469-5711 USA
3. Sandia National Laboratories P.O. Box 5800 Albuquerque NM 87185 USA