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Aufsatz
On A Hybrid Concept for Approximating Self‐Excited Periodic Oscillations of Large‐Scaled Dynamical Systems
(2021-01-25)
Concerning the approximation of self‐excited periodic oscillations in large‐scaled mechanical systems involving strong nonlinearities, this contribution suggests a concept for an efficient treatment. The presented Hybrid FD‐HB method takes the advantages of both schemes Harmonic Balance and Finite Difference to enhance the ratio of computational cost and accuracy for mechanical systems with many degrees of freedom. Within this contribution the residual equations, required when applying a NEWTON‐RAPHSON‐scheme, are ...
Aufsatz
The influence of magnetic field on nanoparticle transport in a micro channel
(2021-01-25)
The present study focuses on a new solver considering the effect of magnetic field on nanoparticles concentration in a micro size channel. To describe the multi component behavior of blood, the Euler‐Euler method is used. Particles are modeled by a concentration equation considering a magnetic drift. The influence of a realistic magnetic field on nanoparticles is investigated. A result for a test case is presented. It shows that the magnetic body force resulting from nanoparticles also influence the hematocrit ...
Aufsatz
Psychische Belastungen bei Müllwerkern – Konsequenzen für die Beratungstätigkeit
(2021-01-26)
Um die psychischen Belastungen von Müllwerkern zu erheben, wurde eine Bestandsaufnahme mit der Berufsgruppe vorgenommen, die Erkenntnisse für die spätere Beratungstätigkeit lieferte. Die Erhebung der Belastungen in Gruppendiskussionen wurde durch eine teilnehmende Beobachtung ergänzt, was einen psychodynamischen Blick auf die Besonderheiten der Organisation rund um den Müllwagen und die Charakteristika der Müllwerker erlaubte. Die Ergebnisse zeigen, dass ein Zusammenhang zwischen den Belastungen und dem beruflichen ...
Aufsatz
The J-integral for mixed-mode loaded cracks with cohesive zones
(2020-11-23)
The J-integral quantifies the loading of a crack tip, just as the crack tip opening displacement (CTOD) emanating from the cohesive zone model. Both quantities, being based on fundamentally different interpretations of cracks in fracture mechanics of brittle or ductile materials, have been proven to be equivalent in the late 60s of the previous century, however, just for the simple mode-I loading case. The relation of J and CTOD turned out to be uniquely determined by the constitutive law of the cohesive zone in front ...
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
Heat Pump Bridge Analysis using the Modified Energy Transfer Diagram
(2020-12-29)
Heat pumps are the key technology to decarbonise thermal processes by upgrading industrial surplus heat using renewable electricity. Existing insight-based integration methods refer to the idealised Grand Composite Curve requiring the full exploitation of heat recovery potential but leave the question of how to deal with technical or economic limitations unanswered. In this work, a novel Heat Pump Bridge Analysis (HPBA) is introduced for practically targeting technical and economic heat pump potential by applying ...
Aufsatz
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
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
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 ...