Birgit Luber ([email protected]) Joelle Deplazes ([email protected]) Gisela Keller ([email protected]) Axel Walch ([email protected]) Sandra Rauser ([email protected]) Martin Eichmann ([email protected]) Rupert Langer ([email protected]) Heinz Höfler ([email protected]) Susanna Hegewisch-Becker (hegewisch@t-on...

Plasma turbulence in a linear device is explored for the first time with three-dimensional global two-fluid simulations, focusing on the plasma parameters of the Large Plasma Device. Three instabilities are present in the simulations: the Kelvin-Helmholtz instability, a sheath-driven instability, and a resistive drift wave instability. The Kelvin-Helmholtz mode is shown to dominate the transpor...

One of the current challenges to understanding neural information processing in biological systems is to decipher the "code" carried by large populations of neurons acting in parallel. We present an algorithm for automated discovery of stochastic firing patterns in large ensembles of neurons. The algorithm, from the "Helmholtz Machine" family, attempts to predict the observed spike patterns in ...

CLASSICAL SCATTERING OF ELECTROMAGNETIC RADIATION Light is an electromagnetic disturbance which is propagated by vector wave equations which are readily derived from Maxwell's equations. The Helmholtz wave equation results from Maxwell's equations. The Helmholtz equation is linear; thus, superposition of solutions is allowed. Huygens' principle is that a point source of light will give rise to ...

Loreen Zegenhagen1,2*, Chaitanya Kurhade3, Andrea Kröger1,2 and Anna K Överby3 1Institute of Medical Microbiology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany 2Innate Immunity and Infection, Helmholtz Centre for Infection Research, Braunschweig, Germany 3Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden *Corresponding author: Loreen Zegenhagen, Institut...

Quantification of cardiac function is important for the assessment of abnormalities and response to therapy. We present a method to reconstruct dense cardiac motion from sparse features in tagging MRI, decomposed into solenoidal and irrotational parts using multi-scale Helmholtz decomposition. Reconstruction is based on energy minimization using covariant derivatives exploiting prior knowledge ...

We present an iterative solution method for the discrete high wavenumber Helmholtz equation. The basic idea of the solution method, already presented in [18], is to develop a preconditioner which is based on a Helmholtz operator with a complex-valued shift, for a Krylov subspace iterative method. The preconditioner, which can be seen as a strongly damped wave equation in Fourier space, can be a...

Zoological Researchmuseum Alexander Koenig, Adenauerallee 160, D-53113 Bonn, Germany Department of Wildlife Sciences, University of Göttingen, Büsgenweg 3, D-37077 Göttingen, Germany Helmholtz Centre for Environmental Research – UFZ, Department of Computational Landscape Ecology, Permoserstraße 15, D-04318 Leipzig, Germany Helmholtz Centre for Environmental Research – UFZ, Department of Communi...

Since supp f ⊂ Ω, uθ satisfies the plain Helmholtz equation with constant wavenumber outside of Ω, the radiation condition and uθ|∂Ω = gθ. So by solving the exterior problem of the Helmholtz equation (analytically if Ω is a circle), uθ can be computed everywhere outside of Ω without prior knowledge of f . In particular, we can compute h = ∂uθ ∂ν on ∂Ω. Thus, our original problem can be rewritte...

In 1983, a preconditioner was proposed [J. Comput. Phys. 49 (1983) 443] based on the Laplace operator for solving the discrete Helmholtz equation efficiently with CGNR. The preconditioner is especially effective for low wavenumber cases where the linear system is slightly indefinite. Laird [Preconditioned iterative solution of the 2D Helmholtz equation, First Year’s Report, St. Hugh’s College, ...