Continuum-kinematics-based peridynamics and phase-field approximation of non-local dynamic fracture

In this work, two non-local approaches to dynamic fracture are investigated: a novel peridynamic formulation and a variational phase-field approach. The chosen continuum-kinematics-based peridynamic model extends the current peridynamic models by introducing surface and volume-based interactions. The phase-field fracture approach optimizes the body’s potential energy and provides a reliable method for predicting fracture in finite element computations. Both methods are able to efficiently compute crack propagation even when the cracks have arbitrary or complex patterns. We discuss the relations of critical fracture parameters in the two methods and show that our novel damage model for the continuum-kinematics-based peridynamics effectively manages fracture under dynamic loading conditions. Numerical examples demonstrate a good agreement between both methods in terms of crack propagation, fracture pattern, and in part, critical loading. We also show the limitations of the methods and discuss possible reasons for deviations

Euclid: Modelling massive neutrinos in cosmology -- a code comparison

The measurement of the absolute neutrino mass scale from cosmological large-scale clustering data is one of the key science goals of the Euclid mission. Such a measurement relies on precise modelling of the impact of neutrinos on structure formation, which can be studied with $N$-body simulations. Here we present the results from a major code comparison effort to establish the maturity and reliability of numerical methods for treating massive neutrinos. The comparison includes eleven full $N$-body implementations (not all of them independent), two $N$-body schemes with approximate time integration, and four additional codes that directly predict or emulate the matter power spectrum. Using a common set of initial data we quantify the relative agreement on the nonlinear power spectrum of cold dark matter and baryons and, for the $N$-body codes, also the relative agreement on the bispectrum, halo mass function, and halo bias. We find that the different numerical implementations produce fully consistent results. We can therefore be confident that we can model the impact of massive neutrinos at the sub-percent level in the most common summary statistics. We also provide a code validation pipeline for future reference.Comment: 43 pages, 17 figures, 2 tables; published on behalf of the Euclid Consortium; data available at https://doi.org/10.5281/zenodo.729797

Open Access-Tag 2016 "Aktiv sein – etwas bewegen": Grußworte des Referenten Forschung und wissenschaftlicher Nachwuchs

Das vorliegende Grußwort wurde anlässlich des Open Access-Tages 2016 der Technischen Universität Chemnitz durch den Referenten (Schwerpunkt Forschung und wissenschaftlicher Nachwuchs) im Büro des Rektors der TU Chemnitz gehalten. Der Redner ging auf die zunehmende Bedeutung von Open Access ein und hob die diesbezüglichen Services der Universitätsbibliothek hervor.The welcome speech was held on Open Access Day 2016 of Technische Universität Chemnitz by Michael Partmann, Assistant (specialized in Research and Junior Researchers) in the Rector’s Office. The speaker mentioned the increasing importance of Open Access and highlighted the relevant services of the University Library