1. Department of Civil Engineering, University of Minnesota, 500 Pillsbury Dr. S.E., Minneapolis, MN 55455 e-mail:
2. Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue S.E., Minneapolis, MN 55455 e-mail:
3. Department of Mechanical Engineering, University of Minnesota, 111 Church Street, Minneapolis, MN 55455 e-mail: