1. Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, 404 Westwood Plaza, Los Angeles, CA 90095;
2. Department of Mechanical Engineering, Western New England University, 1215 Wilbraham Road, Springfield, MA 01119 e-mails: ;
3. Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, 404 Westwood Plaza, Los Angeles, CA 90095 e-mail: