1. Dr.-Ing. Dipl.-Geophys., Work Group Leader of Non-Destructive Testing Group, Institute of Construction Materials, Univ. of Stuttgart, Stuttgart, Germany.
2. Professor, Dr.-Ing., Director of the Institute of Construction Materials, Institute of Construction Materials, Univ. of Stuttgart, Stuttgart, Germany.
3. Dipl.-Geophys., PhD Student, Institute of Construction Materials, Univ. of Stuttgart, Stuttgart, Germany.