1. Department of Industrial and Systems Engineering, University of Wisconsin-Madison, 3255 Mechanical Engineering, 1513 University Avenue, Madison, WI 53706 e-mail:
2. Department of Industrial and Systems Engineering, University of Wisconsin-Madison, 3270 Mechanical Engineering, 1513 University Avenue, Madison, WI 53706 e-mail:
3. Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, 48-121G Eng IV, Los Angeles, CA 90095 e-mail: