1. Pearlstone Center for Aeronautical Engineering Studies, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
2. Department of Civil Engineering, Academic College of Judea and Samaria, Ariel 44837, Israel
3. on leave from Department of Mechanical Engineering, Florida International University, Miami, FL 33199
4. Mechanical Engineering Department, Carnegie-Mellon University, Pittsburgh, PA 15213