Heiko Andrä

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The level-set method has been recently introduced in the field of shape optimization, enabling a smooth representation of the boundaries on a fixed mesh and therefore leading to fast numerical algorithms. However, most of these algorithms use a Hamilton-Jacobi equation to connect the evolution of the level-set function with the deformation of the contours,(More)
In surgical knee replacement, the damaged knee joint is replaced with artificial prostheses. An accurate clinical evaluation must be carried out before applying knee prostheses to ensure optimal outcome from surgical operations and to reduce the probability of having long-term problems. Useful information can be inferred from estimates of the stress acting(More)
We present autoionization spectra of metastable Ar and C, N, O and Ne scattering off an Al(111) surface with incident energies down to 5eV. The unprecedented quality of the experimental data permits the observation of a unique, yet undiscovered peak in the structures originating from the metastable projectiles compared to corresponding ground state(More)
Applying a modified quantum beat method, the hyperfine splittings of 14NIII 2p 2P3/2 are determined to 03BD3/2,5/2 = (252.0 ± 1.1) MHz and 03BD1/2,3/2 = (126.2 ± 0.4) MHz. From the frequencies we deduce the nuclear electric quadrupole moment of 14N Q (14N) = (19.4 ± 0.9) mb and the quadrupole coupling constant for the 2p-electron in 14NIII 1s22s22p 2P3/2 :(More)
A virtual design method for medium density fiberboards (MDF) is proposed with the aim to optimize the fiber orientation and lay-up of MDF. The new method estimates the stiffness and strength by using microstructure models of the MDF fiber network. The virtual design is used to improve the manufacturing technology of MDF plates with multilayer oriented fiber(More)
Multi-Scale Simulation of Viscoelastic Fiber-Reinforced Composites Sarah Ricker, Heiko Andrä, Stefan Frei, Matthias Kabel, Fabian Krzikalla, Inga Shyklar, and Aivars Zemitis 1 Department of Flow and Material Simulation, Fraunhofer Institute for Industrial Mathematics (ITWM), Kaiserslautern, Germany 2 Department of Geophysics, Stanford University, Stanford,(More)
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