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See detailXFEM coupling of granular flows interacting with surrounding fluids
Pasenow, F.; Zilian, Andreas UL; Dinkler, D.

in ECCOMAS 2012 - European Congress on Computational Methods in Applied Sciences and Engineering, e-Book Full Papers (2012)

In this paper, ideas for the simulation of sliding dry granular materials interacting with surrounding fluids are presented and first results are presented. The compressible granular material is modeled ... [more ▼]

In this paper, ideas for the simulation of sliding dry granular materials interacting with surrounding fluids are presented and first results are presented. The compressible granular material is modeled as a medium which can show solid-like and fluid-like characteristics. Therefore a weighted decomposition of stress tensors of a solid-like and a fluid-like phase is applied. The surrounding incompressible fluids are described with a Newtonian constitutive model. Interface dynamics are handled with the level-set method. The model equations are discretized with the space-time finite element method. Discontinuous solution characteristics across interfaces are captured numerically by the extended finite element method (XFEM). For all discontinuities the space of ansatz functions is enriched with Heaviside functions. [less ▲]

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See detailXFEM coupling techniques for landslide-fluid interaction
Pasenow, Frithjof; Zilian, Andreas UL

Scientific Conference (2011)

Selected topographies on earth are threatened by sudden landslides on natural or artificial hillsides. Dur- ing landslides natural granular materials exhibit phase transitions from solid-like to fluid ... [more ▼]

Selected topographies on earth are threatened by sudden landslides on natural or artificial hillsides. Dur- ing landslides natural granular materials exhibit phase transitions from solid-like to fluid-like behavior [1]. In order to describe such materials interacting with surrounding fluids a material formulation allow- ing a switch from solid- to fluid-like state is developed. The solid-like state of the granular is modeled as compressible elastic material in an eulerian framework, while the surrounding fluid is described by an incompressible newtonian fluid. Discretization of the balance equations is carried out with a stabilized space-time finite element method [2]. The domain of elastic material utilizes mixed-hybrid space-time elements while for the surrounding fluid standard velocity-pressure elements [3] are used. Interaction of both continua is described with an interface-coupled formulation where the level-set technique [4] is employed for the interface motion. The challenge of the introduced model is the coupling of fields with discontinuous state variables as well as fieldwise different state variables. Available coupling techniques in the context of the extended finite element method and based on localized mixed hybrid formulations [5] will be discussed and evaluated numerically by means of selected 2D examples. [less ▲]

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See detailXFEM modelling of delamination in composite materials
Cahill, L.; Natarajan, S.; McCarthy, C. et al

Scientific Conference (2010)

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See detailXFEM with global enrichment for 3D cracks
Agathos, Kostas; Chatzi, Eleni; Bordas, Stéphane UL et al

Scientific Conference (2015, June 17)

We present an extended finite element method (XFEM) based on fixed area enrichment which 1) suppresses the difficulties associated with ill-conditioning, even for "large" enrichment radii; 2) requires 50 ... [more ▼]

We present an extended finite element method (XFEM) based on fixed area enrichment which 1) suppresses the difficulties associated with ill-conditioning, even for "large" enrichment radii; 2) requires 50 times fewer enriched degrees of freedom (for a typical mesh) as the standard XFEM with geometrical enrichment (for the same or better accuracy level); 3) increases the accuracy level of the stress intensity factors and leads to "smooth" stress intensity variations along the crack front. [less ▲]

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See detailXLME interpolants, a seamless bridge between XFEM and enriched meshless methods
Amiri, F.; Anitescu, C.; Arroyo, M. et al

in Computational Mechanics (2013)

In this paper, we develop a method based on local maximum entropy shape functions together with enrichment functions used in partition of unity methods to discretize problems in linear elastic fracture ... [more ▼]

In this paper, we develop a method based on local maximum entropy shape functions together with enrichment functions used in partition of unity methods to discretize problems in linear elastic fracture mechanics. We obtain improved accuracy relative to the standard extended finite element method at a comparable computational cost. In addition, we keep the advantages of the LME shape functions, such as smoothness and non-negativity. We show numerically that optimal convergence (same as in FEM) for energy norm and stress intensity factors can be obtained through the use of geometric (fixed area) enrichment with no special treatment of the nodes near the crack such as blending or shifting. © 2013 Springer-Verlag Berlin Heidelberg. [less ▲]

Detailed reference viewed: 335 (1 UL)
See detailAn XML Format Secure protocol-OpenSST
Zhang, Xinhua UL; Jiang, Chunyan; Meinel, Christoph

in The 3rd ACS/IEEE International Conference on Computer Systems and Applications (2005)

OpenSST (Open Simple Secure Transaction) is a free software project and aims to create an efficient, open and secure alternative to the secure proprietary transaction protocol. OpenSST uses XML syntax to ... [more ▼]

OpenSST (Open Simple Secure Transaction) is a free software project and aims to create an efficient, open and secure alternative to the secure proprietary transaction protocol. OpenSST uses XML syntax to specify its message format, and relies on prevalent cryptographic algorithms to secure the transaction. OpenSST is designed to provide user with the guarantee on confidentiality, integrity, authenticity and non-repudiation. One feature of OpenSST's is that it defines a simple message structure so that it can easily be integrated into different usage frameworks. This paper mainly describes OpenSST's logic architecture and message format through an http-based prototype. [less ▲]

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See detailXPS Modeling of Immobilized Recombinant Angiogenin and Apoliprotein A1 on Biodegradable Nanofibers
Manakhov, Anton; Permyakova, Elizaveta; Ershov, Sergey UL et al

in Nanomaterials (2020), 10(5), 879

The immobilization of viable proteins is an important step in engineering efficient scaffolds for regenerative medicine. For example, angiogenin, a vascular growth factor, can be considered a neurotrophic ... [more ▼]

The immobilization of viable proteins is an important step in engineering efficient scaffolds for regenerative medicine. For example, angiogenin, a vascular growth factor, can be considered a neurotrophic factor, influencing the neurogenesis, viability, and migration of neurons. Angiogenin shows an exceptional combination of angiogenic, neurotrophic, neuroprotective, antibacterial, and antioxidant activities. Therefore, this protein is a promising molecule that can be immobilized on carriers used for tissue engineering, particularly for diseases that are complicated by neurotrophic and vascular disorders. Another highly important and viable protein is apoliprotein A1. Nevertheless, the immobilization of these proteins onto promising biodegradable nanofibers has not been tested before. In this work, we carefully studied the immobilization of human recombinant angiogenin and apoliprotein A1 onto plasma-coated nanofibers. We developed a new methodology for the quantification of the protein density of these proteins using X-ray photoelectron spectroscopy (XPS) and modeled the XPS data for angiogenin and apoliprotein A1 (Apo-A1). These findings were also confirmed by the analysis of immobilized Apo-A1 using fluorescent microscopy. The presented methodology was validated by the analysis of fibronectin on the surface of plasma-coated poly(ε-caprolactone) (PCL) nanofibers. This methodology can be expanded for other proteins and it should help to quantify the density of proteins on surfaces using routine XPS data treatment. [less ▲]

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See detailXVII. ročník setkání historikù a příznivců orální historie na hradě Sovinci
Bronec, Jakub UL

in Marginalia Historica : Časopis pro Dějiny Vzdělanosti a Kultury (2019), 5(1), 245

Letošní ročník červnové konference v prostorách středověkého hradu Sovinec v Severomoravském kraji spojená s workshopem byla tradičně zaměřena na prezentaci právě probíhajících projektů realizovaných ... [more ▼]

Letošní ročník červnové konference v prostorách středověkého hradu Sovinec v Severomoravském kraji spojená s workshopem byla tradičně zaměřena na prezentaci právě probíhajících projektů realizovaných metodou orální historie. Účast na setkání byla podmíněna aktivním příspěvkem s délkou maximálně dvaceti minut. [less ▲]

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See detailXXIV Workshop on Geometric Methods in Physics, Bialowieza, Poland, June 26 - July 2, 2005, Proceedings Special issue of the Journal of Geometry and Symmetry in Physics, containting vol. 5 and 6
Ali, Syed Twareque UL; Gazeau, Jean-Pierre; Goldin, Gerald A. et al

Book published by Institute of Biophysics, Bulgarian Academy of Sciences (2006)

Detailed reference viewed: 43 (0 UL)
See detailXXIX workshop on geometric methods in physics, Bia\lowie\Dza Poland, June 27 -- July 3, 2010. Selected papers based on the presentations at the workshop.
Kielanowski, Piotr; Buchstaber, Victor; Anatol, Odzijewicz et al

Book published by AIP Conference Proceedings 1307. Melville, NY: American Institute of Physics (AIP). ix, 220~p. EUR~129.95/net; SFR~151.00; \sterling~95.00 \$~142.00 (2010)

The articles of this volume will be reviewed individually.

Detailed reference viewed: 53 (1 UL)
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See detailXXth ISRA World Meeting 2012 at the University of Luxembourg. Abstract Book
Scientific Program Committee and Organization Committee; Melzer, André UL

Book published by Université du Luxembourg (2012)

Detailed reference viewed: 80 (2 UL)
See detailXXVIII Workshop on Geometrical Methods in Physics, Bialowieza, Poland, 28 June - 4 July 2009
Kielanowski, Piotr; Odzijewicz, Anatol; Schlichenmaier, Martin UL

Book published by AIP (2009)

Detailed reference viewed: 46 (3 UL)
See detailY wie Ybalon
Heimböckel, Dieter UL

Article for general public (2013)

Detailed reference viewed: 65 (0 UL)
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See detailYAC – Young People and COVID-19
Residori, Caroline UL; Schomaker, Léa UL; Samuel, Robin UL

Speeches/Talks (2020)

Presentation of the first results from the "Young People and COVID-19 (YAC)" study, combining results from an representative online survey and in-depth interviews

Detailed reference viewed: 77 (10 UL)
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See detailYAC – Young People and COVID-19. Preliminary Results of a Representative Survey of Adolescents and Young Adults in Luxembourg
Residori, Caroline UL; Sozio, Maria Eugenia; Schomaker, Léa UL et al

Report (2020)

Overall, the preliminary results of the representative survey of adolescents and young adults in Luxembourg paint a complex picture. In general, young people seem to be aware of their responsibility to ... [more ▼]

Overall, the preliminary results of the representative survey of adolescents and young adults in Luxembourg paint a complex picture. In general, young people seem to be aware of their responsibility to contain the coronavirus. The majority have the necessary information and opportunities to act in a way that reflects this responsibility. There are suggestions of negative impacts stemming from COVID-19 and measures to combat COVID-19, but these do not appear to be the prevailing dynamic at the time of completing the survey. However, it is likely that negative effects will increase the longer the COVID-19 pandemic lasts and the more individual and social resources are depleted. There are already detectable beginnings of sociodemographic and socioeconomic differences in how people are coping with the COVID-19 pandemic. It is therefore important to continue to provide young people with support for mastering the transition between childhood and adulthood despite COVID-19 and to responsibly provide them with the opportunities and spaces this requires. This process must pay particular attention to inequalities that are developing and being reinforced. [less ▲]

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See detailYactul: An Extensible Game-Based Student Response Framework for Active Learning
Grevisse, Christian UL; Botev, Jean UL; Rothkugel, Steffen UL

in Ponencias del XVIII Encuentro Internacional Virtual Educa, Colombia 2017 (2017)

Student response systems as an active learning strategy have shown to be useful in different study domains. With the advent of gamification, these environments have become very popular to improve student ... [more ▼]

Student response systems as an active learning strategy have shown to be useful in different study domains. With the advent of gamification, these environments have become very popular to improve student engagement. However, existing solutions only provide a static set of activity types and limit their use to classrooms. In this paper, we present Yactul, an extensible game-based student response framework for active learning. Our ecosystem fosters continuous learning both in the collaborative setting of the classroom and the private study environment of the student. Our modular architecture enables a seamless integration of activities from a broad and extensible set. In addition, a mobile app for offline learning extends the experience outside the classroom and allows to replay quizzes anywhere and anytime, track the progress of an individual learner and suggest activities on topics that require more studying. [less ▲]

Detailed reference viewed: 354 (116 UL)
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See detailYale Symposium on Art and Gender
Penasse, Julien UL

Scientific Conference (2018, March 29)

Detailed reference viewed: 37 (1 UL)
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See detailYang-Mills fields and random holonomy along Brownian bridges
Arnaudon, Marc; Thalmaier, Anton UL

in Annals of Probability (2003), 31(2), 769-790

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See detailA year of monitoring 20 mesophilic full-scale bioreactors reveals the existence of stable but different core microbiomes in bio-waste and wastewater anaerobic digestion systems.
Calusinska, Magdalena; Goux, Xavier; Fossepre, Marie et al

in Biotechnology for biofuels (2018), 11

Background: Anaerobic digestion (AD) is a microbe-driven process of biomass decomposition to CH4 and CO2. In addition to renewable and cost-effective energy production, AD has emerged in the European ... [more ▼]

Background: Anaerobic digestion (AD) is a microbe-driven process of biomass decomposition to CH4 and CO2. In addition to renewable and cost-effective energy production, AD has emerged in the European Union as an environmentally friendly model of bio-waste valorisation and nutrient recycling. Nevertheless, due to the high diversity of uncharacterised microbes, a typical AD microbiome is still considered as "dark matter". Results: Using the high-throughput sequencing of small rRNA gene, and a monthly monitoring of the physicochemical parameters for 20 different mesophilic full-scale bioreactors over 1 year, we generated a detailed view of AD microbial ecology towards a better understanding of factors that influence and shape these communities. By studying the broadly distributed OTUs present in over 80% of analysed samples, we identified putatively important core bacteria and archaea to the AD process that accounted for over 70% of the whole microbial community relative abundances. AD reactors localised at the wastewater treatment plants were shown to operate with distinct core microbiomes than the agricultural and bio-waste treating biogas units. We also showed that both the core microbiomes were composed of low (with average community abundance </= 1%) and highly abundant microbial populations; the vast majority of which remains yet uncharacterised, e.g. abundant candidate Cloacimonetes. Using non-metric multidimensional scaling, we observed microorganisms grouping into clusters that well reflected the origin of the samples, e.g. wastewater versus agricultural and bio-waste treating biogas units. The calculated diversity patterns differed markedly between the different community clusters, mainly due to the presence of highly diverse and dynamic transient species. Core microbial communities appeared relatively stable over the monitoring period. Conclusions: In this study, we characterised microbial communities in different AD systems that were monitored over a 1-year period. Evidences were shown to support the concept of a core community driving the AD process, whereas the vast majority of dominant microorganisms remain yet to be characterised. [less ▲]

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