Max-Planck-Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany. ginkel@mpi-magdeburg.mpg.de|Max-Planck-Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany. ginkel@mpi-magdeburg.mpg.de|Max-Planck-Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany. ginkel@mpi-magdeburg.mpg.de|Max-Planck-Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany. ginkel@mpi-magdeburg.mpg.de|Max-Planck-Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany. ginkel@mpi-magdeburg.mpg.de