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See detailParents, schools and multilingual children
Aleksic, Gabrijela UL; Bebic, Dzoen Dominique UL

Conference given outside the academic context (2020)

Early literacy skills are critical for children’s later academic achievement. A wealth of research showed that children’s home languages should not be abandoned, as they are crucial for promoting dynamic ... [more ▼]

Early literacy skills are critical for children’s later academic achievement. A wealth of research showed that children’s home languages should not be abandoned, as they are crucial for promoting dynamic multilingualism, assuring cross-linguistic transfer and developing identities. To explore home literacy environment and family language policy of language minority preschool children in Luxembourg, we obtained 600 parent questionnaires, tested 226 children age 4 to 6 in their home languages and Luxembourgish, and interviewed 32 families. The results from the questionnaires showed that the home resources and parent involvement influenced children’s language awareness and their print knowledge irrespective of parent’s education and their wealth. Concerning children’s competences in Luxembourgish, children with positive attitudes towards their school did better than their peers in other schools. In the interviews, parents explained that maintaining home language is important for keeping connections with family, friends and their culture. This is the language parents feel emotionally connected to and the easiest to transmit to their children. Language maintenance is mostly achieved through conversations, movies, games and books in the home languages, children’s attendance of language schools on weekends, celebrations of traditions as well as holidays in the native country of the parents. The home language is, however, not something parents enforce too strictly, as they mostly correct the children’s linguistic mistakes by simple repetition. It is often with great pride that parents report their children having an excellent proficiency in their home language. Finally, through our professional development training in translanguaging we are helping teachers to integrate children’s different home languages and cultures into the classroom and strengthen the home-school collaboration in order to support children’s well-being, learning and identities. [less ▲]

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See detailDESIGN AND OPTIMIZATION OF SIMULTANEOUS WIRELESS INFORMATION AND POWER TRANSFER SYSTEMS
Gautam, Sumit UL

Doctoral thesis (2020)

The recent trends in the domain of wireless communications indicate severe upcoming challenges, both in terms of infrastructure as well as design of novel techniques. On the other hand, the world ... [more ▼]

The recent trends in the domain of wireless communications indicate severe upcoming challenges, both in terms of infrastructure as well as design of novel techniques. On the other hand, the world population keeps witnessing or hearing about new generations of mobile/wireless technologies within every half to one decade. It is certain the wireless communication systems have enabled the exchange of information without any physical cable(s), however, the dependence of the mobile devices on the power cables still persist. Each passing year unveils several critical challenges related to the increasing capacity and performance needs, power optimization at complex hardware circuitries, mobility of the users, and demand for even better energy efficiency algorithms at the wireless devices. Moreover, an additional issue is raised in the form of continuous battery drainage at these limited-power devices for sufficing their assertive demands. In this regard, optimal performance at any device is heavily constrained by either wired, or an inductive based wireless recharging of the equipment on a continuous basis. This process is very inconvenient and such a problem is foreseen to persist in future, irrespective of the wireless communication method used. Recently, a promising idea for simultaneous wireless radio-frequency (RF) transmission of information and energy came into spotlight during the last decade. This technique does not only guarantee a more flexible recharging alternative, but also ensures its co-existence with any of the existing (RF-based) or alternatively proposed methods of wireless communications, such as visible light communications (VLC) (e.g., Light Fidelity (Li-Fi)), optical communications (e.g., LASER-equipped communication systems), and far-envisioned quantum-based communication systems. In addition, this scheme is expected to cater to the needs of many current and future technologies like wearable devices, sensors used in hazardous areas, 5G and beyond, etc. This Thesis presents a detailed investigation of several interesting scenarios in this direction, specifically concerning design and optimization of such RF-based power transfer systems. The first chapter of this Thesis provides a detailed overview of the considered topic, which serves as the foundation step. The details include the highlights about its main contributions, discussion about the adopted mathematical (optimization) tools, and further refined minutiae about its organization. Following this, a detailed survey on the wireless power transmission (WPT) techniques is provided, which includes the discussion about historical developments of WPT comprising its present forms, consideration of WPT with wireless communications, and its compatibility with the existing techniques. Moreover, a review on various types of RF energy harvesting (EH) modules is incorporated, along with a brief and general overview on the system modeling, the modeling assumptions, and recent industrial considerations. Furthermore, this Thesis work has been divided into three main research topics, as follows. Firstly, the notion of simultaneous wireless information and power transmission (SWIPT) is investigated in conjunction with the cooperative systems framework consisting of single source, multiple relays and multiple users. In this context, several interesting aspects like relay selection, multi-carrier, and resource allocation are considered, along with problem formulations dealing with either maximization of throughput, maximization of harvested energy, or both. Secondly, this Thesis builds up on the idea of transmit precoder design for wireless multigroup multicasting systems in conjunction with SWIPT. Herein, the advantages of adopting separate multicasting and energy precoder designs are illustrated, where we investigate the benefits of multiple antenna transmitters by exploiting the similarities between broadcasting information and wirelessly transferring power. The proposed design does not only facilitates the SWIPT mechanism, but may also serve as a potential candidate to complement the separate waveform designing mechanism with exclusive RF signals meant for information and power transmissions, respectively. Lastly, a novel mechanism is developed to establish a relationship between the SWIPT and cache-enabled cooperative systems. In this direction, benefits of adopting the SWIPT-caching framework are illustrated, with special emphasis on an enhanced rate-energy (R-E) trade-off in contrast to the traditional SWIPT systems. The common notion in the context of SWIPT revolves around the transmission of information, and storage of power. In this vein, the proposed work investigates the system wherein both information and power can be transmitted and stored. The Thesis finally concludes with insights on the future directions and open research challenges associated with the considered framework. [less ▲]

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See detailRadial processes for sub-Riemannian Brownian motions and applications
Baudoin, Fabrice; Grong, Erlend; Kuwada, Kazumasa et al

E-print/Working paper (2020)

We study the radial part of sub-Riemannian Brownian motion in the context of totally geodesic foliations. Itô's formula is proved for the radial processes associated to Riemannian distances approximating ... [more ▼]

We study the radial part of sub-Riemannian Brownian motion in the context of totally geodesic foliations. Itô's formula is proved for the radial processes associated to Riemannian distances approximating the Riemannian one. We deduce very general stochastic completeness criteria for the sub-Riemannian Brownian motion. In the context of Sasakian foliations and H-type groups, one can push the analysis further, and taking advantage of the recently proved sub-Laplacian comparison theorems one can compare the radial processes for the sub-Riemannian distance to one-dimensional model diffusions. As a geometric application, we prove Cheng's type estimates for the Dirichlet eigenvalues of the sub-Riemannian metric balls, a result which seems to be new even in the Heisenberg group. [less ▲]

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See detailMeasuring Pants
Doan, Nhat Minh UL; Parlier, Hugo UL; Tan, Ser Peow

E-print/Working paper (2020)

We investigate the terms arising in an identity for hyperbolic surfaces proved by Luo and Tan, namely showing that they vary monotonically in terms of lengths and that they verify certain convexity ... [more ▼]

We investigate the terms arising in an identity for hyperbolic surfaces proved by Luo and Tan, namely showing that they vary monotonically in terms of lengths and that they verify certain convexity properties. Using these properties, we deduce two results. As a first application, we show how to deduce a theorem of Thurston which states, in particular for closed hyperbolic surfaces, that if a simple length spectrum "dominates" another, then in fact the two surfaces are isometric. As a second application, we show how to find upper bounds on the number of pairs of pants of bounded length that only depend on the boundary length and the topology of the surface. [less ▲]

Detailed reference viewed: 103 (56 UL)
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See detailLa promesse de Dupong...
Scuto, Denis UL

Article for general public (2020)

Despite the promise that foreign Jews who had resided in Luxembourg before the war and had to flee nazi persecution, could come back after the war, Luxembourg authorities restricted the return of the ... [more ▼]

Despite the promise that foreign Jews who had resided in Luxembourg before the war and had to flee nazi persecution, could come back after the war, Luxembourg authorities restricted the return of the foreign Jews who had survived and made an application to return and settle in the Grand-Duchy. The article is based on the analysis of a database of more than 3.000 foreign Jews who had resided in Luxembourg in the 1930s. More than 400 foreign Jews tried to return after the war. [less ▲]

Detailed reference viewed: 76 (4 UL)
See detailArchivage et patrimoine nativement numérique
Schafer, Valerie UL

Presentation (2020, February 07)

Intervention sur l'archivage du Web en déclinant/discutant l'argumentaire de la séance– Les garanties des libertés numériques (notamment sur les enjeux de souveraineté nationale / l'interopérabilité des ... [more ▼]

Intervention sur l'archivage du Web en déclinant/discutant l'argumentaire de la séance– Les garanties des libertés numériques (notamment sur les enjeux de souveraineté nationale / l'interopérabilité des données etc.) Argumentaire de la séance : L’effectivité des droits et libertés numériques constitue une condition nécessaire de la confiance des citoyens dans les biens et services numériques. Créer les conditions de l’effectivité des libertés numériques représente à l’évidence un enjeu central pour les prochaines années. Les outils juridiques destinés à garantir l’effectivité des libertés numériques font l’objet d’intenses débats, comme par exemple s’agissant de la souveraineté numérique, de la transparence des données et des algorithmes, de la portabilité ou de l’interopérabilité des données. [less ▲]

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See detailUniversity vs. Research Institute? The Dual Pillars of German Science Production, 1950–2010
Dusdal, Jennifer UL; Powell, Justin J W UL; Baker, David UL et al

in Minerva: A Review of Science, Learning and Policy (2020)

The world’s third largest producer of scientific research, Germany, is the origin of the research university and the independent, extra-university research institute. Its dual-pillar research policy ... [more ▼]

The world’s third largest producer of scientific research, Germany, is the origin of the research university and the independent, extra-university research institute. Its dual-pillar research policy differentiates these organizational forms functionally: universities specialize in advanced research-based teaching; institutes specialize intensely on research. Over the past decades this policy affected each sector differently: while universities suffered a lingering “legitimation crisis,” institutes enjoyed deepening “favored sponsorship”—financial and reputational advantages. Universities led the nation’s reestablishment of scientific prominence among the highly competitive European and global science systems after WWII. But sectoral analysis of contributions to science, technology, engineering, mathematics, and medical and health journal publications (1950–2010) finds that Germany’s small to medium-sized independent research institutes have made significant, growing contributions, particularly in publishing in higher impact journals proportionally more than their size. Simultaneously—despite dual-pillar policy implications—the university sector continues to be absolutely and relatively successful; not eclipsed by the institutes. Universities have consistently produced two-thirds of the nation’s publications in the highest quality journals since at least 1980 and have increased publications at a logarithmic rate; higher than the international mean. Indeed, they led Germany into the global mega-science style of production. Contrary to assumed benefits of functional differentiation, our results indicate that relative to their size, each sector has produced approximately similar publication records. While institutes have succeeded, the larger university sector, despite much less funding growth, has remained fundamental to German science production. Considering these findings, we discuss the future utility of the dual-pillar policy. [less ▲]

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See detailOptimization assisted redesigning a structure of a hydrogen valve: the redesign process and numerical evaluations
Cao, Thanh Binh UL; Kedziora, Slawomir UL; Sellen, Stephan UL et al

in International Journal on Interactive Design and Manufacturing (2020)

This study introduced the redesign process of an automotive hydrogen valve. The process relied on the structural optimization approach, which used to build up the new valves having promising stiffness and ... [more ▼]

This study introduced the redesign process of an automotive hydrogen valve. The process relied on the structural optimization approach, which used to build up the new valves having promising stiffness and the lowest possible weights. To achieve the goals, the study was proposed to be taken place via the three main stages. These stages included topology optimization, lattice optimization, as well as numerical evaluations. The achieved results firstly indicated that the two newly designed valves possessed longer life and lower mass than the original valve. Especially, the topology optimized one could withstand more than 5E4 working cycles in the pre-treated condition before the first crack would be nucleated. The results also pointed out the influences of the pre-treatment pressure on the fatigue performance of the hydrogen valve. Within the examined ranges of the pressure, increasing the pressure’s magnitudes tended to shorten the fatigue life of the topology optimized valve. Additionally, the results highlighted the impact of the employed materials on the estimated fatigue life of such a non-treated structure. In the highlights, the considered steel valves could function normally far beyond 1.5E5 working cycles while the aluminum valves would have an initial crack formation prior to reaching 3E3 cycles. The results also suggested that further practical evidence is needed to not only confirm whether the selected printed aluminum is among the promising candidate materials of the hydrogen valve but also to support the described evaluations. [less ▲]

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See detailOn the order of the reductions of algebraic numbers
Sgobba, Pietro UL

Presentation (2020, February 06)

Let K be a number field, and let G be a finitely generated and torsion-free subgroup of K*. For almost all primes p of K, we consider the order of the cyclic group (G mod p), and ask whether this number ... [more ▼]

Let K be a number field, and let G be a finitely generated and torsion-free subgroup of K*. For almost all primes p of K, we consider the order of the cyclic group (G mod p), and ask whether this number lies in a given arithmetic progression. The density of primes for which this condition holds exists (this generalizes a result of Ziegler from 2006) and it is, under certain assumptions, a computable positive rational number. We also present a uniformity property concerning some special cases. This is a joint work with A. Perucca. [less ▲]

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See detailEffects of Annealing and Light on Co-evaporated Methylammonium Lead Iodide Perovskites using Kelvin Probe Force Microscopy in Ultra-High Vacuum
Gallet, Thibaut UL; Martin Lanzoni, Evandro UL; Redinger, Alex UL

in 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) (2020, February 06)

Careful surface analysis is essential to understand the electronic and ionic behaviors in perovskite absorbers. In this contribution we discuss Kelvin probe force microscopy performed in ultra-high vacuum ... [more ▼]

Careful surface analysis is essential to understand the electronic and ionic behaviors in perovskite absorbers. In this contribution we discuss Kelvin probe force microscopy performed in ultra-high vacuum on as-grown and annealed co-evaporated methylammonium lead iodide perovskite thin films. By comparing the contact potential difference upon annealing and illumination, we find that annealing increases the average workfunction, indicating a change either in doping or in surface composition. Illumination also increases the average workfunction, indicating a p-type absorber, by reducing band bending as the photo-generated carriers screen the surface states. The effect of light shows a two-step process, with a first fast trend, linked to the surface photovoltage and a second slower trend indicating a possible redistribution of mobile charges. [less ▲]

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See detailDenis Scuto an Dr. Gerben Zaagsma iwwer den FORUM Z Holocaust: History and Memory
Zaagsma, Gerben UL; Scuto, Denis UL

Diverse speeches and writings (2020)

Déi zwee Historiker erzielen iwwer den FORUM Z, organiséiert vum C2DH, deen haut iwwer den Theema Holocaust: History and Memory, geet. De Forum zu Mondorf an der Orangerie vum Thermalbad ass agedeelt an ... [more ▼]

Déi zwee Historiker erzielen iwwer den FORUM Z, organiséiert vum C2DH, deen haut iwwer den Theema Holocaust: History and Memory, geet. De Forum zu Mondorf an der Orangerie vum Thermalbad ass agedeelt an dräi Deeler: 1. The Holocaust and Jewish life in Luxembourg: filling the gaps 2. Holocaust research in the digital age 3. Combating anti-Semitism in contemporary Europe [less ▲]

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See detailRoundtable - Combating anti-Semitism in contemporary Europe
Zaagsma, Gerben UL; Santer, Georges; Feldman, David et al

Diverse speeches and writings (2020)

Roundtable Combating anti-Semitism in contemporary Europe What is the state of anti-Semitism in Europe, and Luxembourg, today? How can it be situated within the broader context of rising hate speech and ... [more ▼]

Roundtable Combating anti-Semitism in contemporary Europe What is the state of anti-Semitism in Europe, and Luxembourg, today? How can it be situated within the broader context of rising hate speech and crime, online and offline? What methods are being proposed to combat it? How does it relate to politics and the broader memory battles that are being fought in Europe today? These will be the themes addressed during a round table discussion with the following participants: - Dr. Gerben Zaagsma (moderator, C²DH) - Georges Santer (Ambassador, Chair of the International Holocaust Remembrance Alliance/IHRA) - Prof. David Feldman (Director, Pears Institute for the Study of Antisemitism, Birkbeck, University of London) - François Moyse (Chair, European Association for the Preservation and Promotion of Jewish Culture and Heritage) [less ▲]

Detailed reference viewed: 31 (1 UL)
See detailLe relations belgo-luxembourgeoises: une mise en perspective historique
Brüll, Christoph UL

Scientific Conference (2020, February 05)

Detailed reference viewed: 21 (0 UL)
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See detailOpening the black box of the social learning process: The case of community of practices
Boughattas, Yosra; Geraudel, Mickaël UL; Claeye, Frederic

Scientific Conference (2020, February 04)

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See detailUrban Green Amenity and City Structure
Tran, Thi Thu Huyen UL

Doctoral thesis (2020)

One of the main components that make cities attractive to their residents is their public park and garden systems. Green urban areas from a small community garden to famous areas such as `Jardin du ... [more ▼]

One of the main components that make cities attractive to their residents is their public park and garden systems. Green urban areas from a small community garden to famous areas such as `Jardin du Luxembourg' in Paris not only shape the face of the city but are a quintessential aspect of the quality of life for local inhabitants. They offer places for local recreation, beautiful views, cleaner air and many other advantages. Recent research has validated the connection between urban parks and the well-being of the city's inhabitants. Although green urban areas might seem to be meagre in comparison with other natural ecosystems such as wetlands or forests, the value of the environmental, recreational, and other services they offer is likely to be disproportionally high due to their strategic locations. This dissertation focuses on studying the optimal provision of green urban areas and the welfare effects of a substantial change in green provision policies in the presence of other types of land uses and adverse shocks. It comprises four papers (chapters). [less ▲]

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See detailN point Virasoro algebras considered as Krichever - Novikov type algebras
Schlichenmaier, Martin UL

Scientific Conference (2020, February 04)

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See detailInfluence of pubic symphysis stiffness on pelvic load distribution during single leg stance
Ricci, Pierre-Louis; Maas, Stefan UL; Gerich, Torsten et al

in International Journal of Numerical Methods in Biomedical Engineering (2020)

This study focuses on the influence of the softening and stiffening of pubic symphysis on the load distribution within the bones of the pelvic ring under the physiological loadings of the single leg ... [more ▼]

This study focuses on the influence of the softening and stiffening of pubic symphysis on the load distribution within the bones of the pelvic ring under the physiological loadings of the single leg stance. Muscle forces and joint reaction forces were first determined by inverse dynamics and applied to a linear finite element model of the pelvis. With normal pubic symphysis stiffness, high Von Mises stresses are located on the anterior surface to the sacrum around the sacroiliac joint and on the superior ramus, both on the side of the weightbearing leg. Softening of the pubic symphysis redirects the load backward, decreases the stresses at the anterior pelvis, and increases them at the posterior pelvis. A stiffening of the pubic symphysis redirects the load forward, increases the load on the posterior pelvis, and decreases them at the anterior pelvis. This investigation highlights the significance of the pubic symphysis on the load distribution of the pelvis and in maintaining the integrity of the structures. Its role should not be neglected when analyzing the pelvis. [less ▲]

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See detailClassifications of quasitrivial semigroups
Devillet, Jimmy UL; Marichal, Jean-Luc UL; Teheux, Bruno UL

in Semigroup Forum (2020), 100(3), 743-764

We investigate classifications of quasitrivial semigroups defined by certain equivalence relations. The subclass of quasitrivial semigroups that preserve a given total ordering is also investigated. In ... [more ▼]

We investigate classifications of quasitrivial semigroups defined by certain equivalence relations. The subclass of quasitrivial semigroups that preserve a given total ordering is also investigated. In the special case of finite semigroups, we address and solve several related enumeration problems. [less ▲]

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See detailChristof Schöch lectures on the Use and Abuse of Word Embedding
Kamlovskaya, Ekaterina UL

Article for general public (2020)

A blog post reporting on a lecture about the use of word embeddings in humanities.

Detailed reference viewed: 31 (1 UL)