Biomedical subjects

Beatrix M Schulz

Publications and source records attributed to Beatrix M Schulz.

2 recordsLinked to original sources

PubMed2003

Shear-induced solid-fluid transition in a wet granular medium.

We present a numerical study of a shear-induced solid-fluid transition in wet granular matter. The simulation is based on a simple model that considers both the cohesive forces induced by the adsorbed liquid amount and the repulsive forces due to the excluded volume interaction of the granules. Dissipation is assumed to be entirely due to the hysteretic character of the cohesive forces. In particular, we analyze the dynamics of the system close to the phase transition from solidlike behavior to a mobile ergodic state under the influence of an external force field F, when the latter exceeds a critical force F(c). Diffusion coefficients, dissipation, and kinetic order parameters can be expressed as characteristic scaling laws.

Journal Article↗

PubMed2002

Random walks with feedback on fractal lattices.

We study numerically a random walk under the competitive processes of a self-organized feedback coupling, characterized by a strength lambda and an underlying fractal lattice. Whereas a fractal structure favors a subdiffusive behavior, a dynamical feedback leads either to localization in case of an attractive feedback, lambda>0, or to superdiffusion for a repulsive memory strength lambda<0. Under the influence of both processes the dynamical exponent z is changed. For a Sierpinski gasket or a Sierpinski carpet with repulsive feedback coupling we get 2/z=1.04 or 2/z=1.08, respectively. When an attractive feedback is dominant, the system offers localization as in the case of a random walk in regular lattices. The numerical results are strongly supported by analytical studies based on scaling arguments.

Journal Article↗