References of "2020"
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See detailIntegrated likelihood based inference for nonlinear panel data models with unobserved effects
Schumann, Martin; Severini, Thomas A.; Tripathi, Gautam UL

Presentation (2020, December 01)

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See detailA hybrid MGA-MSGD ANN training approach for approximate solution of linear elliptic PDEs
Dehghani, Hamidreza UL; Zilian, Andreas UL

E-print/Working paper (2020)

We introduce a hybrid "Modified Genetic Algorithm-Multilevel Stochastic Gradient Descent" (MGA-MSGD) training algorithm that considerably improves accuracy and efficiency of solving 3D mechanical problems ... [more ▼]

We introduce a hybrid "Modified Genetic Algorithm-Multilevel Stochastic Gradient Descent" (MGA-MSGD) training algorithm that considerably improves accuracy and efficiency of solving 3D mechanical problems described, in strong-form, by PDEs via ANNs (Artificial Neural Networks). This presented approach allows the selection of a number of locations of interest at which the state variables are expected to fulfil the governing equations associated with a physical problem. Unlike classical PDE approximation methods such as finite differences or the finite element method, there is no need to establish and reconstruct the physical field quantity throughout the computational domain in order to predict the mechanical response at specific locations of interest. The basic idea of MGA-MSGD is the manipulation of the learnable parameters’ components responsible for the error explosion so that we can train the network with relatively larger learning rates which avoids trapping in local minima. The proposed training approach is less sensitive to the learning rate value, training points density and distribution, and the random initial parameters. The distance function to minimise is where we introduce the PDEs including any physical laws and conditions (so-called, Physics Informed ANN). The Genetic algorithm is modified to be suitable for this type of ANN in which a Coarse-level Stochastic Gradient Descent (CSGD) is exploited to make the decision of the offspring qualification. Employing the presented approach, a considerable improvement in both accuracy and efficiency, compared with standard training algorithms such classical SGD and Adam optimiser, is observed. The local displacement accuracy is studied and ensured by introducing the results of Finite Element Method (FEM) at sufficiently fine mesh as the reference displacements. A slightly more complex problem is solved ensuring the feasibility of the methodology [less ▲]

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See detailOpinion Statement ECJ-TF 2/2020 on the ECJ Decision of 3 March 2020 in Vodafone Magyarország Mobil Távközlési Zrt. (Case C-75/18) on Progressive Turnover Taxes
García Prats, Alfredo; Haslehner, Werner UL; Heydt, Volker et al

in European Taxation (2020), 60(12), 555-564

This CFE Opinion Statement discusses the decision of the Grand Chamber of the ECJ in Vodafone. The Court held that the imposition of the Hungarian progressive turnover-based tax on the telecommunications ... [more ▼]

This CFE Opinion Statement discusses the decision of the Grand Chamber of the ECJ in Vodafone. The Court held that the imposition of the Hungarian progressive turnover-based tax on the telecommunications sector did not infringe the EU fundamental freedoms or article 401 of the VAT Directive (2006/112), and that the question regarding the prohibition of State aid was inadmissible. Vodafone is especially important in respect of the current debate regarding turnover-based digital services taxes. [less ▲]

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See detailSensitivity Analysis on Regularity Based Driver Advisory Systems
Laskaris, Georgios; Seredynski, Marcin; Viti, Francesco UL

in 2020 IEEE 23rd International Conference on Intelligent Transportation Systems (ITSC) (2020, December)

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See detailDouble-Graded Quantum Superplane
Bruce, Andrew UL; Duplij, Steven

in Reports on Mathematical Physics (2020), 86(3), 383-400

A ℤ2 × ℤ2-graded generalisation of the quantum superplane is proposed and studied. We construct a bicovariant calculus on what we shall refer to as the double-graded quantum superplane. The ommutation ... [more ▼]

A ℤ2 × ℤ2-graded generalisation of the quantum superplane is proposed and studied. We construct a bicovariant calculus on what we shall refer to as the double-graded quantum superplane. The ommutation rules between the coordinates, their differentials and partial derivatives are explicitly given. Furthermore, we show that an extended version of the double-graded quantum superplane admits a natural Hopf -algebra structure. [less ▲]

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See detailConstant Envelope MIMO-OFDM Precoding for Low Complexity Large-Scale Antenna Array Systems
Domouchtsidis, Stavros UL; Tsinos, Christos UL; Chatzinotas, Symeon UL et al

in IEEE Transactions on Wireless Communications (2020)

Herein, we consider constant envelope precoding in a multiple-input multiple-output orthogonal frequency division multiplexing system (CE MIMO-OFDM) for frequency selective channels. In CE precoding the ... [more ▼]

Herein, we consider constant envelope precoding in a multiple-input multiple-output orthogonal frequency division multiplexing system (CE MIMO-OFDM) for frequency selective channels. In CE precoding the signals for each transmit antenna are designed to have constant amplitude regardless of the channel realization and the information symbols that must be conveyed to the users. This facilitates the use of power-efficient components, such as phase shifters (PS) and nonlinear power amplifiers, which are key for the feasibility of large-scale antenna array systems because of their low cost and power consumption. The CE precoding problem is firstly formulated as a least-squares problem with a unit modulus constraint and solved using an algorithm based on coordinate descent. The large number of optimization variables in the case of the MIMO-OFDM system motivates the search for a more computationally efficient solution. To tackle this, we reformulate the CE precoding design into an unconstrained nonlinear least-squares problem, which is solved efficiently using the Gauss-Newton algorithm. Simulation results underline the efficiency of the proposed solutions and show that they outperform state of the art techniques. [less ▲]

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See detailA comparison of constitutive models for describing the flow of uncured styrene-butadiene rubber
Rehor, Martin UL; Gansen, Alex UL; Sill, Clemens et al

in Journal of Non-Newtonian Fluid Mechanics (2020), 286

Uncured styrene-butadiene rubber (SBR) can be modelled as a viscoelastic material with at least two different relaxation mechanisms. In this paper we compare multi-mode constitutive models combining two ... [more ▼]

Uncured styrene-butadiene rubber (SBR) can be modelled as a viscoelastic material with at least two different relaxation mechanisms. In this paper we compare multi-mode constitutive models combining two viscoelastic modes (linear and/or nonlinear) in three possible ways. Our particular choice of the two modes was inspired by models originally developed to describe the response of asphalt binders. We select the model that best fits the experimental data obtained from a modified stress relaxation experiment in the torsional configuration of the plate-plate rheometer. The optimisation of the five model parameters for each model is achieved by minimising the weighted least-squares distance between experimental observations and the computer model output using a tree-structured Parzen estimator algorithm to find an initial guess, followed by further optimisation using the Nelder-Mead simplex algorithm. The results show that the model combining the linear mode and the nonlinear mode is the most suitable variant to describe the observed behavior of SBR in the given regime. The predictive capabilities of the three models are further examined in changed experimental and numerical configurations. Full data and code to produce the figures in this article are included as supplementary material. [less ▲]

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See detailÖkologie, Kultur, Großregion: Einführende Überlegungen zu einem komplexen und vielschichtigen Verhältnis
Thiltges, Sébastian UL; Solte-Gresser, Christiane

in Thiltges, Sébastian; Solte-Gresser, Christiane (Eds.) Kulturökologie und ökologische Kulturen in der Großregion (2020, December)

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See detailTowards 2-Hop Neighbor Management for Heterogeneous Vehicular Networks
Turcanu, Ion UL; Kim, Minsuk; Klingler, Florian

Poster (2020, December)

Message dissemination protocols for vehicular networks often build upon information maintained in neighbor tables. Due to high mobility and scarce channel capacity available in such networks, algorithms ... [more ▼]

Message dissemination protocols for vehicular networks often build upon information maintained in neighbor tables. Due to high mobility and scarce channel capacity available in such networks, algorithms for maintaining neighbor tables must carefully select which information is transmitted at which time. Recent approaches rely on probabilistic data structures (e.g., Bloom filter) for transmitting such neighbor information in order to reduce channel load, yet they still suffer from scarce channel capacities. In this paper, we propose to use multiple communication technologies (heterogeneous networking) for maintaining neighbor tables by building upon recent 2-hop neighbor management strategies. Promising results show an increase of up to 19 % of covered neighbors in comparison to a Baseline approach that only uses one communication technology. [less ▲]

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See detailA cascading Kalman filtering framework for real-time urban network flow estimation
Rinaldi, Marco UL; Viti, Francesco UL

in 2020 IEEE 23rd International Conference on Intelligent Transportation Systems (ITSC) (2020, December)

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See detailPerception of immigration to Iceland: The host country perspective
Murdock, Elke UL

in Meckl, Markus; Gunnþórsdóttir, Hermina (Eds.) Samfélag fjölbreytileikans: Samskipti heimamanna og innflytjenda á Íslandi. (2020)

With 35.5 immigrants per 1000 inhabitants, Iceland had the third highest number of immigrants per inhabitants in Europe in 2018. Until the turn of the century, the foreign population percentage in Iceland ... [more ▼]

With 35.5 immigrants per 1000 inhabitants, Iceland had the third highest number of immigrants per inhabitants in Europe in 2018. Until the turn of the century, the foreign population percentage in Iceland was around 2%. In the last 5 years, this percentage has risen steadily to nearly 14% in 2020. How is this rapid rise in immigration experienced by the host country population? How are immigrants perceived and what are expectations in terms of behavior? The Inclusive Societies – Iceland project investigated both, the immigrants’ situation in Iceland, but also the native populations’ attitude towards immigration and immigrants. It is important to take the host country perspective into consideration, as diversity ideologies will also determine the acculturation options for minorities. A quantitative survey was conducted among 3630 native Icelanders (51.1% women, MAge = 50.8, SD = 15.6), spread across all regions of Iceland. The questions covered a range of domains pertinent to life in Iceland. In this Chapter only the questions pertaining directly to immigration and immigrants are analyzed. The results indicate that culture contact takes place – with, over two thirds of participants indicating that they have invited immigrants to their home and slightly under two thirds having been invited to immigrants’ homes. Overall, the perception is that immigrants have made a positive impact to communities. The vast majority of participants expect immigrants to learn Icelandic. The greatest divergence of views was found concerning the question, if immigrants should adopt Icelandic customs and values. The findings will be discussed in light of policy implications. [less ▲]

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See detailMultiple Vulnerabilities: The Effects of Neighborhood Structural Changes upon Older Residents’ Mental Health and Perceptions of the Broader Community
Settels, Jason UL

in Journal of Community Psychology (2020)

Neighborhoods' structural conditions are consequential for their social circumstances and residents' well‐being. Neighborhood effects might be accentuated among older residents because their daily ... [more ▼]

Neighborhoods' structural conditions are consequential for their social circumstances and residents' well‐being. Neighborhood effects might be accentuated among older residents because their daily activities and social lives are more confined to their immediate communities. This study examines how changing neighborhood socioeconomic disadvantage affects older residents' depression and stress, as well as perceptions of neighborhood context. This study employed waves 2 (2010–2011) and 3 (2015–2016) of the National Social Life, Health, and Aging Project survey (N= 2357) and fixed‐effects linear regression models to study these relationships. While rising neighborhood socioeconomic disadvantage was associated with more depression and stress, it was negatively associated with overall neighborhood social capital and neighborhood social cohesion, and was only associated with lower perceptions of neighborhood safety among respondents who relocated to new neighborhoods. Beyond cross‐sectional associations, changing neighborhood socioeconomic disadvantage is associated with changes in mental health and perceptions of neighborhood social context. [less ▲]

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See detailEvaluating Pretrained Transformer-based Models on the Task of Fine-Grained Named Entity Recognition
Lothritz, Cedric UL; Allix, Kevin UL; Veiber, Lisa UL et al

in Proceedings of the 28th International Conference on Computational Linguistics (2020, December)

Named Entity Recognition (NER) is a fundamental Natural Language Processing (NLP) task and has remained an active research field. In recent years, transformer models and more specifically the BERT model ... [more ▼]

Named Entity Recognition (NER) is a fundamental Natural Language Processing (NLP) task and has remained an active research field. In recent years, transformer models and more specifically the BERT model developed at Google revolutionised the field of NLP. While the performance of transformer-based approaches such as BERT has been studied for NER, there has not yet been a study for the fine-grained Named Entity Recognition (FG-NER) task. In this paper, we compare three transformer-based models (BERT, RoBERTa, and XLNet) to two non-transformer-based models (CRF and BiLSTM-CNN-CRF). Furthermore, we apply each model to a multitude of distinct domains. We find that transformer-based models incrementally outperform the studied non-transformer-based models in most domains with respect to the F1 score. Furthermore, we find that the choice of domains significantly influenced the performance regardless of the respective data size or the model chosen. [less ▲]

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See detailPublicly provided healthcare and migration
Mahe, Clotilde UL

in Economics and Human Biology (2020), 39

Publicly provided healthcare has received growing attention. Debates have been fuelled by evidence on improved health and reduced poverty, and concerns over adverse labour market effects; concerns that ... [more ▼]

Publicly provided healthcare has received growing attention. Debates have been fuelled by evidence on improved health and reduced poverty, and concerns over adverse labour market effects; concerns that are, to date, only supported by mixed empirical findings. This article examines whether publicly provided healthcare influences the decision to migrate. The spatial and temporal variation in the expansion of a non-contributory health insurance programme in Mexico, combined with the panel dimension and the timing of household survey data allows causal identification of the effect of increased coverage on migration. Difference-in-differences estimates reveal that accessing healthcare for free raises internal migration. The effect on international migration, costlier by nature, is statistically insignificant. Potential mechanisms include better health, the alleviation of financial constraints and a greater propensity to work. Results point to the relevance of including household members who have migrated in assessing the impacts of social health policies. They suggest that publicly provided healthcare could have multiplier effects on economic development and welfare by enabling labour force detachment of working-age members in affiliated households. [less ▲]

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See detailPhase transition for the volume of high-dimensional random polytopes
Bonnet, Gilles; Kabluchko, Zakhar; Turchi, Nicola UL

in Random Structures and Algorithms (2020)

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See detailChanges in school alienation profiles among secondary school students and the role of teaching style: Results from a longitudinal study in Luxembourg and Switzerland
Hadjar, Andreas UL; Grecu, Alyssa; Scharf, Jan et al

in International Journal of Educational Research (2020), early online

What students think about school has a major impact on learning and academic achievement. The multi-domain concept of school alienation distinguishes between alienation from learning, from teachers and ... [more ▼]

What students think about school has a major impact on learning and academic achievement. The multi-domain concept of school alienation distinguishes between alienation from learning, from teachers and from classmates. We aim to study a) alienation patterns among secondary school students, b) how school alienation profiles change from year 7 to year 9 and how secondary school students transition between profiles, and c) the role of teaching style for transitions between school alienation profiles. We draw on panel data of secondary school students from Luxembourg and Switzerland. Results of latent profile/latent transition analyses reveal distinct school alienation profiles, country differences and support for the idea that student-oriented, supportive teaching styles might prevent students from transitioning towards more-highly alienated profiles. [less ▲]

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See detailAR4OER: A Semantic Platform for Open Educational Augmented Reality Resources
Grevisse, Christian UL; Martins Gomes, Carina; Rothkugel, Steffen UL

in Proceedings of the 2020 IEEE International Symposium on Multimedia (2020, December)

Tablet computers are gaining in presence in modern-day classrooms, enabling the use of a variety of apps for purposes such as note-taking or assessment. Augmented Reality (AR) experiences in the classroom ... [more ▼]

Tablet computers are gaining in presence in modern-day classrooms, enabling the use of a variety of apps for purposes such as note-taking or assessment. Augmented Reality (AR) experiences in the classroom, made possible by current hardware, permit new ways of interaction and visualization, as well as increase student motivation and engagement. They also overcome the need for potentially expensive hardware required for experiments in certain scientific domains. The movement of Open Educational Resources (OER) has enabled the sharing of heterogeneous learning resources. Their retrieval can be improved by enriching their metadata using Semantic Web technologies. In this paper, we present AR4OER, a semantic platform for heterogeneous AR experiences provided as OER. We showcase four AR scenarios from different school subjects. These scenarios can be integrated through a lose coupling in third-party apps. Apart from describing how this integration works, we demonstrate how a note-taking app can benefit from these scenarios. [less ▲]

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See detailFrontières liquides : l’eau dans les romans de la terre au Luxembourg
Thiltges, Sébastian UL

in Thiltges, Sébastian; Solte-Gresser, Christiane (Eds.) Ecologie culturelle et cultures écologiques dans la Grande Région (2020, December)

While the earth usually represents the element in which cultural attachment is rooted, water on the contrary reveals what exceeds or interpenetrates the land. The liquid element is as ambiguous as it is ... [more ▼]

While the earth usually represents the element in which cultural attachment is rooted, water on the contrary reveals what exceeds or interpenetrates the land. The liquid element is as ambiguous as it is proteiform: vital and destructive at the same time, it sometimes is a figure of liberation, sometimes of tragic dissolution. In a corpus of Luxembourgish novels from the early 20th century, this paper will analyse the depictions of water, mostly in its opposition with the soil, in order to question the meaning of the liquid element in a context where, corollary to social, economic and political changes, the earth is generally dominant in discourse and imagination. If nature has mostly been confined to the local and cultural landscape, an eco-material reading highlights on the contrary a global and crossborder dimension inherent to nature, but also to culture, disregarding the map-drawn boundaries that define the individual and the collective. Finally, a sensitive, anthropoetical reading also challenges historical, contextual and fictional frames. The materiality of the liquid element is not just a metaphor: it shapes natural, as well as textual environments. [less ▲]

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See detailIn-plane magnetic field-driven symmetry breaking in topological insulator-based three-terminal junctions
Kölzer, Jonas; Moors, Kristof; Schmidt, Thomas UL et al

E-print/Working paper (2020)

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