1. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
2. Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801
3. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801;
4. Center for Design and Optimization, Lawrence Livermore National Laboratory, Livermore, CA 94550