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Aufsatz
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Numerical Simulation of Viscoelastic Fluid‐Structure Interaction Problems and Drug Therapy in the Eye
(2021-01-25)
The vitreous is a fluid‐like viscoelastic transparent medium located in the center of the human eye and is surrounded by hyperelastic structures like the sclera, lens and iris. This naturally gives rise to a fluid‐structure interaction (FSI) problem. While the healthy vitreous is viscoelastic and described by a viscoelastic Burgers‐type equation, the aging vitreous liquefies and is therefore modeled by the Navier‐Stokes equations. We derive a monolithic variational formulation employing the arbitrary Lagrangian ...
Aufsatz
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Damping based on electromagnetic induction: A comparison of different minimal models
(2021-01-25)
Damping of structural vibrations is a crucial part of modern engineering. Using electromagnetic interactions for this purpose is a modern and promising approach. To gain better understanding of phenomena involved in this technique investigations on minimal models of a B‐field modulation dampers are shown. Therefore two different setups are compared. One uses a permanent magnet as the source for the magnetic field, one uses a coil, respectively an electro‐magnet as the source. The contribution focuses on differences ...
Aufsatz
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Soil microbial properties of subalpine steppe soils at different grazing intensities in the Chinese Altai Mountains
(2021-01-18)
Long-term provision of ecosystem services by grasslands is threatened by increasing stocking densities. The functions of grassland ecosystems depend on a mutual relationship between aboveground and belowground biota. While the effects of increasing stocking density on plant biomass are well studied, little is known about its impact on soil microbial properties. To fill this knowledge gap a grazing experiment was conducted on a summer pasture in the Chinese Altai Mountains during the summers of 2014 and 2015 using a ...
Aufsatz
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Derivation of Analytical, Closed‐form Formulas for the Calculations of Instantaneous Screw Axes of Arbitrary Rigid 3D Multi‐Body Systems
(2021-01-25)
A method to calculate the parameters for each instantaneous and relative instantaneous screw axis in an arbitrary rigid multi‐body system is presented. At first a kinematic analysis is performed which calculates the displacements of all nodes and the rotation of each body. In the next step the displacements of the nodes and the rotation of the bodies are used to calculate the instantaneous screw axis of each body. With the information on the instantaneous screw axes the instantaneous relative screw axes can be computed ...
Aufsatz
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Fourier Analysis of DG Schemes for Advection‐Diffusion
(2021-01-25)
This work compares the wave propagation properties of discontinuous Galerkin (DG) schemes for advection‐diffusion problems in particular with respect to the discretization of diffusion terms. Extending previous investigations, the advection discretization now additionally varies between the choices of central or upwind fluxes. The results show that a previously recognized better performance of central schemes for well‐resolved problems only hold for even polynomial degrees and that upwind‐type discretizations also ...
Aufsatz
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Role of Nanoimprint Lithography for Strongly Miniaturized Optical Spectrometers
(2021-01-11)
Optical spectrometers and sensors have gained enormous gimportance in metrology and information technology, frequently involving the question of size, resolution, sensitivity, spectral range, efficiency, reliability, and cost. Nanomaterials and nanotechnological fabrication technologies have huge potential to enable an optimization between these demands, which in some cases are counteracting each other. This paper focuses on the visible and near infrared spectral range and on five types of optical sensors (optical ...
Aufsatz
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Measuring the Time Discretization Error in Linear Elasticity
(2021-01-25)
The present paper considers the spread of longitudinal waves in an elastic rod. On the one hand an analytical solution is presented, on the other hand a spatially and temporally discretized continuum formulation of this problem is treated. With these approaches at hand the appearing time discretization error is analyzed using various quantities.
Aufsatz
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Experimental investigations of viscoelastic and ferroelectric heating in PZT–5H
(2021-01-25)
This contribution focuses on the separation of two effects causing a temperature change in experiments with electrically loaded ferroelectrics. These materials are often subjected to cyclic loading, where viscoelasticity prevails at lower electric fields, whereas dissipative heating by domain switching governs the heating above the coercive field. Different frequencies and load amplitudes are investigated experimentally.
Aufsatz
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Recent Developments in the Field of Modified Patankar-Runge-Kutta-methods
(2021-12-14)
Modified Patankar-Runge-Kutta (MPRK) schemes are numerical one-step methods for the solution of positive and conservative production-destruction systems (PDS). They adapt explicit Runge-Kutta schemes in a way to ensure positivity and conservation of the numerical approximation irrespective of the chosen time step size. Due to nonlinear relationships between the next and current iterate, the stability analysis for such schemes is lacking. In this work, we introduce a strategy to analyze the MPRK22(α)-schemes in the ...