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Aufsatz
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
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
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
Actuation of an elastic membrane by the use of an electrorheological valve
(2021-01-25)
The dynamic response of a fluidic actuator is investigated on the basis of numerical simulations. With this actuator a membrane is excited to oscillate by means of an electrorheological valve. For this purpose the solid and fluid domains are coupled. Furthermore, the constitutive equation of the fluid is coupled to the electric field. The dynamic response is discussed on the example of a variable stiffness of the membrane. Actuators of this type offer the potential to delay the transition of a boundary layer.
Aufsatz
Managing Rangelands Without Herding? Insights From Africa and Beyond
(2020-12-11)
In many parts of the world, the utilization of rangelands is based on the targeted movement of herds within and across often vast territories. Crucial for the success of these livestock operations are decisions on how to flexibly allocate animals to the existing vegetation, both in terms of numbers and concentrations, and in space and time. Research from large scale ranching in the prairies of the Americas, and nomadic or transhumant livestock systems in Africa, the Middle East, and Central Asia, suggests that the ...
Aufsatz
Social dynamics of values, taboos and perceived threats around sacred groves in Kurdistan, Iran
(2020-11-09)
1. Sacred groves are important for the conservation of biodiversity in the Middle East, as more formal approaches to protected areas have often failed in this global biodiversity hotspot.
2. This study aims to identify the most important social values, taboos and perceived threats around sacred groves in the Kurdistan province of Iran. We test whether values, taboos and perceived threats are lost in transmission across generations, with increased urbanisation, and with modernising livelihoods.
3. Our survey of 205 ...
Aufsatz
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
Simultaneous determination of Bingham material parameters using a ball probe concrete rheometer
(2021-01-25)
A new evaluation method allowing direct determination of the Bingham parameters from ball probe rheometers. A non‐linear relationship between the direct measured variables and the material parameters is revealed through numerical parameter studies. The method was validated on two devices of the ball probe type with different dimensions. Comparison with other methods showed good agreement. It is pointed out how the evaluation method can be transferred to devices having other dimensions by performing a limited number ...
Aufsatz
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
The Transformation of Food Culture on the Case of Kyrgyz Nomads - A Historical Overview
(2021-07-27)
The society in Kyrgyzstan experiences a triple burden of malnutrition which occurs when undernutrition, overnutrition and micronutrient deficiency coexists, straining the public health system. This research investigates historical trends of nutrition transition of nomadic and semi-nomadic Kyrgyz and foods consumed earlier before industrialisation and intensification of agriculture started. Qualitative research design inspired by historical analysis and sociological methods were employed. Saturation sampling was used ...