1. European Institute for Energy Research; Emmy-Noether-Str. 11 Karlsruhe 76131 Germany
2. Mathematics Department; INRIA - University Paris-Sud; Bat. 425 91405 Orsay France
3. Industrial Risk Management Department; EDF R&D; 6 quai Watier 78401 Chatou France
4. Toulouse Institute of Mathematics; Paul Sabatier University; Toulouse France