1. Assistant Professor, Charles E. Via Dept. of Civil and Environmental Engineering, Virginia Tech, 200 Patton Hall, Blacksburg, VA, 24061 (corresponding author).
2. Dean, Fu Foundation School of Engineering and Applied Science, and Morris A. and Alma Schapiro Professor, Civil Engineering and Engineering Mechanics, Earth and Environmental Engineering, and Computer Science, Columbia Univ., 510 S.W. Mudd Bldg., 500 W. 120th St., New York, NY 10027.
3. Assistant Professor, Electrical and Computer Engineering, Univ. of Michigan, 1301 Beal Ave., Room 4120, Ann Arbor, MI 48109-2122.