1. Research Group Operations Research and Business Statistics (ORSTAT), Katholieke Universiteit Leuven, Naamsestraat 69, 3000 Leuven, Belgium,
2. Department of Mechanical and Aerospace Engineering, Princeton University, Olden Street, Princeton, NJ 08544-5263, USA,
3. Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Drive, NW Atlanta, GA 30332-0150, USA,