1. Goethe University Frankfurt,Department of Physics,Frankfurt am Main,Germany
2. IMST GmbH,Kamp-Lintfort,Germany
3. Fraunhofer Institute for Structural Durability and System Reliability LBF,Darmstadt,Germany
4. University of Siegen,Department of Mechanical Engineering,Siegen,Germany
5. WindMW Service GmbH,Bremerhaven,Germany