High-Order Numerical Methods for Electromagnetic Induction

The present paper establishes an axisymmetric benchmark model of a conducting loop, which implies an electromagnetic induction. Therein, the fully coupled MAXWELL equations are demonstrated in a monolithic solution strategy. This dynamic problem is solved with a high order finite element discretization using GALERKIN's method in space as well as in time. Furthermore, high order RUNGE-KUTTA time integration methods are analyzed. Studies regarding an h error estimation and the order of convergence are examined. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

The contribution of fundamental frequency, amplitude envelope, and voicing duration cues to speechreading in normal-hearing subjects

The ability to combine speechreading (i.e., lipreading) with prosodic information extracted from the low-frequency regions of speech was evaluated with three normally hearing subjects. The subjects were tested in a connected discourse tracking procedure which measures the rate at which spoken text can be repeated back without any errors. Receptive conditions included speechreading alone (SA), speechreading plus amplitude envelope cues (AM), speechreading plus fundamental frequency cues (FM), and speechreading plus intensity-modulated fundamental frequency cues (AM + FM). In a second experiment, one subject was further tested in a speechreading plus voicing duration cue condition (DUR). Speechreading performance was best in the AM + FM condition (83.6 words per minute,) and worst in the SA condition (41.1 words per minute). Tracking levels in the AM, FM, and DUR conditions were 73.7, 73.6, and 65.4 words per minute, respectively. The average tracking rate obtained when subjects were allowed to listen to the talker's normal (unfiltered) speech (NS condition) was 108.3 words per minute. These results demonstrate that speechreaders can use information related to the rhythm, stress, and intonation patterns of speech to improve their speechreading performance.     

Resonance widths in open microwave cavities studied by harmonic inversion

From the measurement of a reflection spectrum of an open microwave cavity, the poles of the scattering matrix in the complex plane have been determined. The resonances have been extracted by means of the harmonic inversion method. By this, it became possible to resolve the resonances in a regime where the linewidths exceed the mean level spacing up to a factor of 10, a value inaccessible in experiments up to now. The obtained experimental distributions of linewidths were found to be in perfect agreement with predictions from random matrix theory when wall absorption and fluctuations caused by couplings to additional channels are considered.     

Dynamical tunneling in mushroom billiards

We study the fundamental question of dynamical tunneling in generic two-dimensional Hamiltonian systems by considering regular-to-chaotic tunneling rates. Experimentally, we use microwave spectra to investigate a mushroom billiard with adjustable foot height. Numerically, we obtain tunneling rates from high precision eigenvalues using the improved method of particular solutions. Analytically, a prediction is given by extending an approach using a fictitious integrable system to billiards. In contrast to previous approaches for billiards, we find agreement with experimental and numerical data without any free parameter.     

Theory and implementation of orthotropic materials in growing continua

Most biological tissues show a material behavior which is characterized through a pronounced anisotropy. In particular hard tissues such as bones or soft tissues as muscles are commonly modeled as either transversely isotropic or even orthotropic. In contrast to engineering materials, however, biological tissues possess the ability to adapt, e.g. their density, to the current loading situation. Based on a formulation for growth in isotropic continua, see for instance Kuhl, Menzel & Steinmann [3], and transversely isotropic continua as discussed e.g. in Himpel [2], we attend to a model for the functional adaption of orthotropic biomaterials. The material model has been implemented in a finite element code and is studied by means of a numerical example. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)