This work is supported by the Belgian Program on Interuniversity Poles of Attraction, initiated by the Belgian Federal Science
Policy Office, by the KU Leuven-Research Council PFV/10/002
(OPTEC Optimization in Engineering) and by project KP/09/005
(SCORES4CHEM) of the Industrial Research Fund. J. Van Impe holds
the chair Safety Engineering sponsored by the Belgian chemistry
and life sciences federation essenscia.