1. Institute of Technical Thermodynamics, Karlsruhe Institute of Technology, Engelbert-Arnold-Strasse 4, 76131 Karlsruhe, Germany
2. Institute of Thermodynamics, Bundeswehr University of Munich, Werner-Heisenberg-Weg 39, 85577 Neubiberg, Germany
3. Instituto de Matemática e Estatística, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, P. O. Box 15080, Porto Alegre, RS, Brazil