Institutionelles Repositorium der Leibniz Universität Hannover
https://www.repo.uni-hannover.de:443
Das digitale Repositorium erfasst, speichert, erhält, erschließt und verbreitet digitale Forschungsergebnisse.2024-03-18T07:16:14ZOn an objective, geometrically exact coupling element for a director-based multi-body finite element framework
https://www.repo.uni-hannover.de/handle/123456789/16749
On an objective, geometrically exact coupling element for a director-based multi-body finite element framework
Märtins, David; Schuster, Daniel; Hente, Christian; Gebhardt, Cristian Guillermo; Rolfes, Raimund
In multi-body systems, flexible components as well as couplings between them can be subject to large displacements and rotations. This contribution presents a general objective and geometrically exact node-to-node coupling element pursuing two innovations.
Firstly, the coupling element represents a consistent contribution to an existing nonlinear mechanical framework. The coupling element intends to preserve its attributes of objectivity, path-independence, and adherence to the energy-conserving or energy-dissipative time integration method. Secondly, besides elasticity also inertia and damping properties are considered.
For this purpose, a director-based formulation is employed within a total Lagrangian description. The avoidance of an angle-based representation, along with the additive update of state variables, results not only in path-independence but also in the avoidance of accumulating errors during extended simulations. An objective deformation measure is chosen based on the Green-Lagrange strain tensor. The inertia forces are considered by an arbitrarily shaped continuum located at the centre of the coupled nodes. Damping is considered by two different objective first order dissipation functions, which further ensure energy conservation or dissipation.
We successfully demonstrate the coupling element within the mechanical framework on exemplary applications. Firstly, the geometrically exact behaviour is shown compared to a linear deformation measure. Secondly, we numerically indicate the path-independence of the formulation. The dynamic behaviour is demonstrated in a transient analysis of a damped structure. Finally, the modal analysis of a wind turbine shows the application of the coupling element to model the soil-structure interaction.
2023-01-01T00:00:00ZEducation systems as life course policies? The example of subnational educational regimes and young adults’ family transitions
https://www.repo.uni-hannover.de/handle/123456789/16748
Education systems as life course policies? The example of subnational educational regimes and young adults’ family transitions
Bertogg, Ariane; Imdorf, Christian
This study investigates the role of subnational educational opportuni-
ties for three typical transitions in young adulthood: 1) leaving the parental home,
2) starting to cohabit and 3) becoming a parent. Educational opportunities shape
young adults’ life courses as they facilitate the accumulation of human capital, la-
bour market entry and financial independence. Education systems and opportu-
nities are part of transition regimes shaped by the specific cultural, economic and
policy characteristics of a (subnational) context, and are thus likely to affect moving
out and family formation.
Drawing on the example of Switzerland with its large cantonal variation in
educational opportunities, we use longitudinal data from the TREE panel study to
follow a cohort of young adults born in the mid-1980s from ages 16 to 29. Event
history models show that larger shares of young people in vocational education at
a cantonal level are associated with earlier moving out and parenthood, but later
partnership formation. The influence of vocational opportunities is moderated by
the presence of a university in the canton.; Diese Studie untersucht die Rolle subnationaler regionaler Bildungsangebote für drei zentrale Familienübergänge im jungen Erwachsenenalter, nämlich 1) den Auszug aus dem Elternhaus, 2) das Eingehen einer ersten festen Partnerschaft, und 3) den Übergang in die Elternschaft. Bildungsangebote formen Lebensverläufe, da sie die Akkumulation von Humankapitel ermöglichen, den Einstieg in den Arbeitsmarkt erleichtern und die finanzielle Unabhängigkeit junger Menschen von ihren Eltern fördern. Zudem sind sie in Lebensverlaufsregimes eingebettet, welche mit ihren spezifischen kulturellen, ökonomischen und politischen Eigenschaften auch familiäre Übergänge im jungen Erwachsenenalter beeinflussen dürften.
Basierend auf dem Beispiel der Schweiz, die durch eine große regionale Heterogenität in der Bildungslandschaft und der Orientierung in Bildungssystemen gekennzeichnet ist, untersuchen wir den Zusammenhang zwischen kantonalen Bildungsangeboten und den drei genannten Übergängen. Dabei nutzen wir Daten der TREE-Panelstudie, welche die Bildungs-, Arbeitsmarkt- und Lebensverläufe einer Kohorte von jungen Erwachsenen von 16 bis 29 Jahren verfolgt. Event History-Modelle zeigen, dass ein höherer Anteil von jungen Menschen in beruflicher Ausbildung in einem Kanton mit früheren Auszügen und Elternschaft, aber späterer Partnerschaft assoziiert ist. Der Zusammenhang zwischen Übergängen und dem Berufsbildungsangebot wird jedoch von der Verfügbarkeit einer Universität im Kanton moderiert.
2024-03-13T00:00:00ZPublic involvement in the governance of population-level biomedical research: Unresolved questions and future directions
https://www.repo.uni-hannover.de/handle/123456789/16747
Public involvement in the governance of population-level biomedical research: Unresolved questions and future directions
Erikainen, Sonja; Friesen, Phoebe; Rand, Leah; Jongsma, Karin; Dunn, Michael; Sorbie, Annie; McCoy, Matthew; Bell, Jessica; Burgess, Michael; Chen, Haidan; Chico, Vicky; Cunningham-Burley, Sarah; Darbyshire, Julie; Dawson, Rebecca; Evans, Andrew; Fahy, Nick; Finlay, Teresa; Frith, Lucy; Goldenberg, Aaron; Hinton, Lisa; Hoppe, Nils; Hughes, Nigel; Koenig, Barbara; Lignou, Sapfo; McGowan, Michelle; Parker, Michael; Prainsack, Barbara; Shabani, Mahsa; Staunton, Ciara; Thompson, Rachel; Varnai, Kinga; Vayena, Effy; Williams, Oli; Williamson, Max; Chan, Sarah; Sheehan, Mark
Population-level biomedical research offers new opportunities to improve population health, but also raises new challenges to traditional systems of research governance and ethical oversight. Partly in response to these challenges, various models of public involvement in research are being introduced. Yet, the ways in which public involvement should meet governance challenges are not well understood. We conducted a qualitative study with 36 experts and stakeholders using the World Café method to identify key governance challenges and explore how public involvement can meet these challenges. This brief report discusses four cross-cutting themes from the study: the need to move beyond individual consent; issues in benefit and data sharing; the challenge of delineating and understanding publics; and the goal of clarifying justifications for public involvement. The report aims to provide a starting point for making sense of the relationship between public involvement and the governance of population-level biomedical research, showing connections, potential solutions and issues arising at their intersection. We suggest that, in population-level biomedical research, there is a pressing need for a shift away from conventional governance frameworks focused on the individual and towards a focus on collectives, as well as to foreground ethical issues around social justice and develop ways to address cultural diversity, value pluralism and competing stakeholder interests. There are many unresolved questions around how this shift could be realised, but these unresolved questions should form the basis for developing justificatory accounts and frameworks for suitable collective models of public involvement in population-level biomedical research governance.
2020-01-01T00:00:00ZTopic space trajectories: A case study on machine learning literature
https://www.repo.uni-hannover.de/handle/123456789/16744
Topic space trajectories: A case study on machine learning literature
Schaefermeier, Bastian; Stumme, Gerd; Hanika, Tom
The annual number of publications at scientific venues, for example, conferences and journals, is growing quickly. Hence, even for researchers it becomes harder and harder to keep track of research topics and their progress. In this task, researchers can be supported by automated publication analysis. Yet, many such methods result in uninterpretable, purely numerical representations. As an attempt to support human analysts, we present topic space trajectories, a structure that allows for the comprehensible tracking of research topics. We demonstrate how these trajectories can be interpreted based on eight different analysis approaches. To obtain comprehensible results, we employ non-negative matrix factorization as well as suitable visualization techniques. We show the applicability of our approach on a publication corpus spanning 50 years of machine learning research from 32 publication venues. In addition to a thorough introduction of our method, our focus is on an extensive analysis of the results we achieved. Our novel analysis method may be employed for paper classification, for the prediction of future research topics, and for the recommendation of fitting conferences and journals for submitting unpublished work. An advantage in these applications over previous methods lies in the good interpretability of the results obtained through our methods.
2021-01-01T00:00:00Z