1. Lecturer, Dept. of Mechanical Engineering, Univ. of Iowa, 103 South Capitol St., Iowa City, IA 52245 (corresponding author).
2. Professor, Dept. of Aerospace and Mechanical Engineering, Univ. of Arizona, 1130 N. Mountain Ave., Tucson, AZ 85721.
3. Assistant Chief Scientist, Air Force Research Laboratory–Munitions Directorate, 101 West Eglin Blvd., Eglin AFB, FL 32542.