1. Assistant Professor, Dept. of Industrial Studies, Univ. of Wisconsin, Platteville, WI 53818 (corresponding author).
2. Professor, Dept. of Civil Engineering, The Univ. of Texas at Austin, TX 78712.
3. Associate Professor, Dept. of Mechanical Engineering, The Univ. of Texas, Austin, TX 78712.
4. Assistant Professor, Dept. of Civil Engineering, The Univ. of Texas at Austin, TX 78712.