1. Department of Industrial Electrical Engineering and Automation, Lund University, Box 118, SE-221 00 Lund, Sweden (E-mail: christian.rosen@iea.lth.se, ulf.jeppsson@iea.lth.se)
2. BIOMATH, Department of Applied Mathematics, Biometrics and Process Control, Ghent University, Coupure Links 653, B-9000 Gent, Belgium (E-mail: peter.vanrolleghem@ugent.be)