1. Department of Civil and Environmental Engineering; University of Illinois at Urbana-Champaign; 205 North Mathews Avenue, MC-250 Urbana, IL 61801 USA
2. Department of Mechanical Engineering; The University of Akron; Akron OH 44325-3903 USA
3. Department of Aerospace Engineering; University of Illinois at Urbana-Champaign; 104 South Wright Street, MC-236 Urbana IL 61801 USA
4. Department of Mechanical Science and Engineering; University of Illinois at Urbana-Champaign; 1206 West Green Street, MC-244 Urbana IL 61801 USA