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See detailTraffic Management and Networking for Autonomous Vehicular Highway Systems
Rubin, Izhak; Baiocchi, Andrea; Sunyoto, Yulia et al

in Ad Hoc Networks (2019), 83

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See detailSimultaneous finite element analysis of circuit-integrated piezoelectric energy harvesting from fluid-structure interaction
Ravi, Srivathsan; Zilian, Andreas UL

in Mechanical Systems & Signal Processing (2019), 114

Flow-driven piezoelectric energy harvesting is a strongly coupled multiphysics phenomenon that involves complex three-way interaction between the fluid flow, the electromechanical effect of the ... [more ▼]

Flow-driven piezoelectric energy harvesting is a strongly coupled multiphysics phenomenon that involves complex three-way interaction between the fluid flow, the electromechanical effect of the piezoelectric material mounted on a deformable substrate structure and the controlling electrical circuit. High fidelity computational solution approaches are essential for the analysis of flow-driven energy harvesters in order to capture the main physical aspects of the coupled problem and to accurately predict the power output of a harvester. While there are some phenomenological and numerical models for flow-driven harvesters reported in the literature, a fully three-dimensional strongly coupled model has not yet been developed, especially in the context of flow-driven energy harvesting. The weighted residuals method is applied to establish a mixed integral equation describing the incompressible Newtonian flow, elastic substrate structure, piezoelectric patch, equipotential electrode and attached electric circuit that form the multiphysics fluid-structure interaction problem. A monolithic numerical solution method is derived that provides consistent and simultaneous solution to all physical fields as well as to fluid mesh deformation. The approximate solution is based on a mixed space-time finite element discretization with static condensation of the auxiliary fields. The discontinuous Galerkin method is utilized for integrating the monolithic model in time. The proposed solution scheme is illustrated in the example of a lid driven cavity with a flexible piezoelectric bottom wall, demonstrating quantification of the amount of electrical energy extractable from fluid flow by means of a piezoelectric harvester device. The results indicate that in order to make reliable predictions on the power output under varying operational states, the realization of strong multiphysics coupling is required for the mathematical model as well as the numerical solution scheme to capture the characteristics of flow-driven energy harvesters. [less ▲]

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See detailAssessing binge-watching behaviors: Development and validation of the “Watching TV Series Motives” and “Binge-Watching Engagement and Symptoms” questionnaires
Flayelle, Maèva UL; Canale, Natale; Vögele, Claus UL et al

in Computers in Human Behavior (2019), 90

The widespread practice of binge-watching (i.e. watching multiple episodes of a TV series in one session) recently generated concerns about associated negative outcomes. Its psychological investigation ... [more ▼]

The widespread practice of binge-watching (i.e. watching multiple episodes of a TV series in one session) recently generated concerns about associated negative outcomes. Its psychological investigation, however, remains fragmentary. Based on the previous phenomenological investigation of TV series watching, we developed and validated two original assessment instruments, assessing TV series watching motives and binge-watching engagement and symptoms, respectively. Preliminary items were created for each questionnaire, and a focus group with TV series viewers was conducted and analyzed to generate the final instruments. The questionnaires were then administered via an online survey (N=6556), together with complementary measures of affect, problematic Internet use and substance use. Exploratory and confirmatory factor analyses, along with correlational analyses, were performed to examine both structural and external validity of the scales. The factorial analyses resulted in a 4-factor model (i.e. emotional enhancement, enrichment, coping-escapism and social) for the Watching TV Series Motives Questionnaire (WTSMQ), and in a 7-factor model (i.e. engagement, positive emotions, desire-savoring, pleasure preservation, binge-watching, dependency and loss of control) for the Binge-Watching Engagement and Symptoms Questionnaire (BWESQ). The results suggest good psychometric properties for both scales. The current study thus provides theoretically-driven and psychometrically sound instruments for further research on binge-watching behaviors [less ▲]

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See detailReductions of elliptic curves
Perucca, Antonella UL

in Proceedings of the Roman Number Theory Association (2019), 4

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See detailStriking a balance between competitiveness and social fairness: what can we expect from the European Pillar of Social Rights?
Muñoz, Susana UL

in Chiocchetti, Paolo; Allemand, Frédéric (Eds.) Competitiveness and Solidarity in the European Union: Interdisciplinary Perspectives (2019)

The solemnly proclaimed European Pillar of Social Rights provides a meaningful response to the process of building a deeper, fairer European Union in the aftermath of the crisis. This chapter aims to ... [more ▼]

The solemnly proclaimed European Pillar of Social Rights provides a meaningful response to the process of building a deeper, fairer European Union in the aftermath of the crisis. This chapter aims to provide a critical assessment of the nature, scope, rationale, purpose, content and effectiveness of the Pillar in the light of its potential contribution to foster social fairness and competitiveness in the EU. The Pillar complements and develops the EU’s social acquis and reinforces standards which may provide a fairer and more socially-balanced competitiveness in the EU. Progress has been made, but further efforts are needed to build a sense of common purpose to strengthen the social foundations of the Union. [less ▲]

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See detailA Pedagogical Note on Risk Sharing Versus Instability in International Financial Integration: When Obstfeld Meets Stiglitz
Boucekkine, Raouf; Zou, Benteng UL

in Open Economies Review (2019)

The pure risk sharing mechanism implies that financial liberalization is growth enhancing for all countries as the world portfolio shifts from safe low-yield capital to riskier high-yield capital. This ... [more ▼]

The pure risk sharing mechanism implies that financial liberalization is growth enhancing for all countries as the world portfolio shifts from safe low-yield capital to riskier high-yield capital. This result is typically obtained under the assumption that the volatilities for risky assets prevailing under autarky are not altered after liberalization. We relax this assumption within a simple two-country model of intertemporal portfolio choices. By doing so, we put together the risk sharing effect and a well defined instability effect. We identify the conditions under which liberalization may cause a drop in growth. These conditions combine the typical threshold conditions outlined in the literature, which concern the deep characteristics of the economies, and size conditions on the instability effect induced by liberalization. [less ▲]

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See detailClimate politics: how public persuasion affects the trade-off between environmental and economic performance
Prieur, Fabien; Zou, Benteng UL

in Mathematical Social Sciences (2019)

This paper aims at studying the impact of public persuasion, through information dissemination, on environmental and economic performance. A differential game in which opposite interest groups compete for ... [more ▼]

This paper aims at studying the impact of public persuasion, through information dissemination, on environmental and economic performance. A differential game in which opposite interest groups compete for bringing the majority’s environmental concern closer to their views is developed. The results show a strong asymmetry in the impact of public persuasion. It may bring the median voter economy closer to the social optimum in the long run, thereby reducing environmental and economic distorsions. But this only occurs when the environmental group exhibits a radical ideology and people are initially closer to the industrialists’ views. By contrast, economies where industrial groups are powerful and strongly opposed to environmental protection never benefit from the outcome of the game of persuasion. This may explain why the US have failed to take action on global warming up to now. [less ▲]

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See detailTo MigrateWith orWithout Ones’ Children in China - That is the Question
Chen, Yiwen UL; Fromentin, Vincent; Zou, Benteng UL

in Annals of Eceonomcis and statistics (2019)

Where should Chinese internal migrant parents locate their school-aged children: migrate with them or leave them behind? And should they invest in private education of their children? We investigate ... [more ▼]

Where should Chinese internal migrant parents locate their school-aged children: migrate with them or leave them behind? And should they invest in private education of their children? We investigate whether migrant parents can afford to take their children to migrate and thus provide theoretical optimum that maximizes migrant parents’ utility which includes the children’s educational performance. Depending on the educational investment parents make and the relocation cost of children, we provide necessary and sufficient conditions under which migrant parents should take their children to migrate and conditions under which migrant parents should provide their children with private education. [less ▲]

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See detailJewish responses to anti-Semitism in Paris and London in the late 1930s as European Jewish political history
Zaagsma, Gerben UL

in Bajohr, Frank; Löw, Andrea; Wirsching, Andreas (Eds.) Right-Wing Politics and the Rise of Antisemitism in Europe 1935-1941 (2018)

This article compares Jewish responses to antisemitism in Paris and London in the late 1930s, when antisemitism was on the rise in both France and the United Kingdom. There were striking similarities in ... [more ▼]

This article compares Jewish responses to antisemitism in Paris and London in the late 1930s, when antisemitism was on the rise in both France and the United Kingdom. There were striking similarities in these responses, yet local contexts and circumstances dominate the historiographies of both cases. The main aim of this article, then, is not so much to offer new insights into the individual cases (both of which have been abundantly analyzed in historical research), but rather to fill a gap by examining the broader factors that account for these similarities. On the one hand, the article examines the nature of Jewish self-identification in the post-Emancipation era and its effects on the political cultures, practices, and identifications of the actors that were involved; on the other, it explores the way in which these practices were also shaped by migration and transnational aspects. Ultimately, this case study will argue for a comparative and transnational approach to Jewish political history in order to arrive at a better understanding of its diverse configurations and permutations. [less ▲]

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See detailOsiris: Hunting for Integer Bugs in Ethereum Smart Contracts
Ferreira Torres, Christof UL; Schütte, Julian; State, Radu UL

in 34th Annual Computer Security Applications Conference (ACSAC ’18), San Juan, Puerto Rico, USA, December 3-7, 2018 (2018, December)

The capability of executing so-called smart contracts in a decentralised manner is one of the compelling features of modern blockchains. Smart contracts are fully fledged programs which cannot be changed ... [more ▼]

The capability of executing so-called smart contracts in a decentralised manner is one of the compelling features of modern blockchains. Smart contracts are fully fledged programs which cannot be changed once deployed to the blockchain. They typically implement the business logic of distributed apps and carry billions of dollars worth of coins. In that respect, it is imperative that smart contracts are correct and have no vulnerabilities or bugs. However, research has identified different classes of vulnerabilities in smart contracts, some of which led to prominent multi-million dollar fraud cases. In this paper we focus on vulnerabilities related to integer bugs, a class of bugs that is particularly difficult to avoid due to some characteristics of the Ethereum Virtual Machine and the Solidity programming language. In this paper we introduce Osiris – a framework that combines symbolic execution and taint analysis, in order to accurately find integer bugs in Ethereum smart contracts. Osiris detects a greater range of bugs than existing tools, while providing a better specificity of its detection. We have evaluated its performance on a large experimental dataset containing more than 1.2 million smart contracts. We found that 42,108 contracts contain integer bugs. Be- sides being able to identify several vulnerabilities that have been reported in the past few months, we were also able to identify a yet unknown critical vulnerability in a couple of smart contracts that are currently deployed on the Ethereum blockchain. [less ▲]

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See detailSocial Change for Sustainable Localized Food Sovereignty. Convergence between Prosumers and Ethical Entrepreneurs.
Reckinger, Rachel UL

in Sociologia del Lavoro (2018), 152(4),

Recently, some resourceful community-driven initiatives for local food production and retail have arisen in Luxembourg, where low organic agricultural rates are paradoxically paired with high consumer ... [more ▼]

Recently, some resourceful community-driven initiatives for local food production and retail have arisen in Luxembourg, where low organic agricultural rates are paradoxically paired with high consumer demands. This niche of social innovators is combining agro-ecology with circular economy practices. Four cases of alternative food networks are of interest – studied with qualitative interviews and participant observation. One has been established since the 1980s with 200 employees, partly in social insertion measures. The more recent and smaller initiatives are characterized by a cooperative governance, a community-supported agricultural outlook, hands-on workshops and time-banks, all enabled by social media. These initiatives are more radical in their agro-ecological or permaculture practices, focusing on regenerative land use without relying on imports and fostering the integration of consumers with varying degrees of prosumer involvement, as a politicized step further than mere (possibly industrialized) organic production. [less ▲]

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See detailSequential Resource Distribution Technique for Multi-User OFDM-SWIPT based Cooperative Networks
Gautam, Sumit UL; Lagunas, Eva UL; Chatzinotas, Symeon UL et al

Scientific Conference (2018, December)

In this paper, we investigate resource allocation and relay selection in a dual-hop orthogonal frequency division multiplexing (OFDM)-based multi-user network where amplify-and-forward (AF) enabled relays ... [more ▼]

In this paper, we investigate resource allocation and relay selection in a dual-hop orthogonal frequency division multiplexing (OFDM)-based multi-user network where amplify-and-forward (AF) enabled relays facilitate simultaneous wireless information and power transfer (SWIPT) to the end-users. In this context, we address an optimization problem to maximize the end-users’ sum-rate subjected to transmit power and harvested energy constraints. Furthermore, the problem is formulated for both time-switching (TS) and power-splitting (PS) SWIPT schemes.We aim at optimizing the users’ SWIPT splitting factors as well as sub-carrier–destination assignment, sub-carrier pairing, and relay–destination coupling metrics. This kind of joint evaluation is combinatorial in nature with non-linear structure involving mixed-integer programming. In this vein, we propose a sub-optimal low complex sequential resource distribution (SRD) method to solve the aforementioned problem. The performance of the proposed SRD technique is compared with a semi-random resource allocation and relay selection approach. Simulation results reveal the benefits of the proposed design under several parameter values with various operating conditions to illustrate the efficiency of SWIPT schemes for the proposed techniques. [less ▲]

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See detailPower and Load Optimization in Interference-Coupled Non-Orthogonal Multiple Access Networks
Lei, Lei UL; You, Lei; Yang, Yang UL et al

in IEEE Global Communications Conference (GLOBECOM) 2018 (2018, December)

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See detailCollaborative Data Delivery for Smart City-oriented Mobile Crowdsensing Systems
Vitello, Piergiorgio; Capponi, Andrea UL; Fiandrino, Claudio UL et al

in IEEE Global Communications Conference (GLOBECOM), Abu Dhabi, UAE, 2018 (2018, December)

The huge increase of population living in cities calls for a sustainable urban development. Mobile crowdsensing (MCS) leverages participation of active citizens to improve performance of existing sensing ... [more ▼]

The huge increase of population living in cities calls for a sustainable urban development. Mobile crowdsensing (MCS) leverages participation of active citizens to improve performance of existing sensing infrastructures. In typical MCS systems, sensing tasks are allocated and reported on individual-basis. In this paper, we investigate on collaboration among users for data delivery as it brings a number of benefits for both users and sensing campaign organizers and leads to better coordination and use of resources. By taking advantage from proximity, users can employ device-to-device (D2D) communications like Wi-Fi Direct that are more energy efficient than 3G/4G technology. In such scenario, once a group is set, one of its member is elected to be the owner and perform data forwarding to the collector. The efficiency of forming groups and electing suitable owners defines the efficiency of the whole collaborative-based system. This paper proposes three policies optimized for MCS that are compliant with current Android implementation of Wi-Fi Direct. The evaluation results, obtained using CrowdSenSim simulator, demonstrate that collaborative-based approaches outperform significantly individual-based approaches. [less ▲]

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See detailResearching education in Luxembourg (symposium)
Fischbach, Antoine UL

Scientific Conference (2018, November 08)

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See detailPowerMinimizer Symbol-Level Precoding: A Closed-Form Sub-Optimal Solution
Haqiqatnejad, Alireza UL; Kayhan, Farbod UL; Ottersten, Björn UL

in IEEE Signal Processing Letters (2018), 25(11), 1730-1734

In this letter, we study the optimal solution of multiuser symbol-level precoding (SLP) for minimization of the total transmit power under given signal-to-interference-plus noise ratio (SINR) constraints ... [more ▼]

In this letter, we study the optimal solution of multiuser symbol-level precoding (SLP) for minimization of the total transmit power under given signal-to-interference-plus noise ratio (SINR) constraints. Adopting the distance preserving constructive interference regions (DPCIR), we first derive a simplified reformulation of the problem. Then, we analyze the structure of the optimal solution using the Karush-Kuhn-Tucker (KKT) optimality conditions. This leads us to obtain a closed-form sub-optimal SLP solution (CF-SLP) for the original problem. Meanwhile, we obtain the necessary and sufficient condition under which the power minimizer SLP is equivalent to the conventional zero-forcing beamforming (ZFBF). Simulation results show that CF-SLP provides significant gains over ZFBF, while performing quite close to the optimal SLP in scenarios with rather small number of users. The results further indicate that the CF-SLP method has a reduction of order 1000 in computational time compared to the optimal solution. [less ▲]

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See detailAußerschulisches Lesen und Lesekompetenz Zum Zusammenhang zwischen den Deutsch- und Französisch- Lesekompetenzen von Neuntklässlerinnen und Neuntklässlern und ihren außerschulischen Lesegewohnheiten in Luxemburg.
Reichert, Monique UL; Krämer, Charlotte UL; Rivas, Salvador UL et al

Scientific Conference (2018, November)

In Luxemburg erreichen viele Jugendliche ein gutes Lesekompetenzniveau nicht nur in einer, sondern gleich in zwei Sprachen. Allerdings wird wiederholt darauf hingewiesen, dass die Lesekompetenzen in ... [more ▼]

In Luxemburg erreichen viele Jugendliche ein gutes Lesekompetenzniveau nicht nur in einer, sondern gleich in zwei Sprachen. Allerdings wird wiederholt darauf hingewiesen, dass die Lesekompetenzen in Luxemburg stark mit dem familiären Hintergrund der Schülerinnen und Schüler zusammenhängen. Die vorliegende Studie soll jedoch über die Darstellung der Zusammenhänge zwischen den Deutsch- und Französisch-Lesekompetenzen und Einflussfaktoren wie sozio-ökonomischem Hintergrund, Migrationsstatus und Muttersprache hinausgehen. In der Tat stellt sich die Frage, ob es Faktoren gibt, die sich positiv auf das Lesekompetenzniveau der Schülerinnen und Schüler auswirken und auf die sie – anders als bei diesen mittlerweile gut belegten Faktoren – selbst Einfluss nehmen können? Das Leseverhalten Jugendlicher stellt hierfür einen naheliegenden Ansatzpunkt dar. Somit wurden die Schülerinnen und Schüler während der ÉpStan 2016 nicht nur zu ihrem familiären, schulischen und persönlichen Hintergrund befragt, sondern erstmals auch zu ihrem außerschulischen Leseverhalten. Hierbei wurde erfasst, wie häufig sie in ihrer Freizeit Texte unterschiedlicher Art (z. B. Erzählungen, Sachtexte, Zeitungsartikel, Foreneinträge oder Emails) lesen, und in welchen Sprachen sie dies tun. Mittels verschiedener Regressionsanalysen wurde der familiäre Hintergrund der Jugendlichen, ihr Leseverhalten, sowie ihr Lesekompetenzniveau im Deutschen und Französischen zueinander in Bezug gesetzt. Die aus diesen Analysen hervorgehenden Ergebnisse belegen eindrücklich, dass neben dem familiären Hintergrund auch die Lesehäufigkeit und die Sprache, in der die Schülerinnen und Schüler üblicherweise lesen, von Bedeutung für das erreichte Lesekompetenzniveau sind. Darüber hinaus haben insbesondere die Textsorten, mit denen sich die Jugendlichen in ihrer Freizeit auseinandersetzen, entscheidenden Einfluss auf ihre Deutsch- und ihre Französisch-Lesekompetenz. Insbesondere die Häufigkeit, mit der Jugendliche angeben, narrative Texte (wie Geschichten, Romane oder Erzählungen) zu lesen, steht deutlich in positivem Zusammenhang mit ihrer Lesekompetenz in beiden Sprachen. Der Vortrag schließt mit einer Diskussion bezüglich der außerordentlich hohen Attraktivität von digitalen Textsorten bei Kindern und Jugendlichen, und den Möglichkeiten, diese Vielfalt an primär kommunikativ bzw. interaktiv ausgerichteten Lesematerialien als lebensnahe, pädagogische „Sprungbretter“ zu nutzen, mit deren Hilfe zukünftige Leserinnen und Leser an zunehmend komplexere Texte herangeführt werden könnten. [less ▲]

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See detailSustainability: problematizing fragility and ephemerality in digital research - Workshop
Schafer, Valerie UL; Fickers, Andreas UL

Presentation (2018, October 26)

404 not found, closed and opaque corpora, websites disappearance after a few years, obsolete tools, problems of maintenance … this workshop wishes to explore the instability of data, of their digital ... [more ▼]

404 not found, closed and opaque corpora, websites disappearance after a few years, obsolete tools, problems of maintenance … this workshop wishes to explore the instability of data, of their digital (digitalized or/and born-digital) heritage, of digital technologies and tools, the numerous transformations of devices, platforms, terms of use and the tensions between this instability and the necessary stability and reproducibility of research. How should researchers deal at the same time with the ephemeral, the flow, the obsolescence and the concern of knowledge production? How is it possible to reconciliate the temporality of research and the short cycles of technologies? This workshop aims at introducing and identifying the challenges of sustainability and durability which are too often underestimated in digital research and rarely presented to students when introducing tools and research methods. This 120 minutes workshop will be organized in three parts as follows: - Identifying the levels, steps, in which sustainability and durability of a digital research are challenged, from the shaping and sharing of corpora to the maintenance of research results and digital productions. This will be based on the participants experiences and on several examples of research projects; - Mapping the issues and existing solutions such as digital research infrastructures, permanent identifiers, licenses, but also obstacles and limits (such as author rights …) that researchers have to face or take into account; - Creating practical guidelines that could be used by scholars and students. This workshop expands a research project conducted by Christine Barats (Céditec, Université Paris- Est Créteil), Andreas Fickers (Head of C2DH, University of Luxembourg), Valérie Schafer (C2DH, University of Luxembourg). [less ▲]

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