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See detail100 Years of Prandtl's Wedge
Van Baars, Stefan UL

Book published by IOS Press (2018)

The biggest problem for a shallow foundation, just as for any other type of foundation, is a failure due to an overestimation of the bearing capacity. This means that the correct prediction of the bearing ... [more ▼]

The biggest problem for a shallow foundation, just as for any other type of foundation, is a failure due to an overestimation of the bearing capacity. This means that the correct prediction of the bearing capacity of the foundation is often the most important part of the design of a civil structure. That is why the publication by Prandtl in 1920 about the hardness of a plastic body, was a major step in solving the bearing capacity of shallow foundations, although it is well possible that he never realised this, because his solution was not made for civil engineering purposes, but for mechanical purposes. Over the last 100 years, a lot of extensions have been made, for example with inclination factors and shape factors. Also many laboratory experiments have been done and numerical calculations have been made. Some even try to extrapolate the failure mechanism for shallow foundations to the failure mechanism around the tip of a pile. All this scientific work leads back to the first publication by Ludwig Prandtl in 1920. This book, “100 Years of Prandtl’s Wedge”, is intended for all those who are interested in these fundamentals of foundation engineering and their history. The Appendices include a copy of Prandtl’s Über die Härte plastischer Körper and of Reissner’s publication of 1924, Zum Erddruckproblem. [less ▲]

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See detailOvercoming language barriers in early mathematics instruction with “MaGrid” - a language-neutral training tool for multilingual school settings
Cornu, Véronique UL; Pazouki, Tahereh UL; Schiltz, Christine UL et al

Poster (2018, April 08)

Mathematical knowledge at the onset of formal schooling paves the way for children’s achievement in formal mathematics (e.g. Duncan et al., 2007; Watts et al., 2014). Hence, it is crucial to equip ... [more ▼]

Mathematical knowledge at the onset of formal schooling paves the way for children’s achievement in formal mathematics (e.g. Duncan et al., 2007; Watts et al., 2014). Hence, it is crucial to equip children with sound basic mathematical competencies by deploying effective teaching interventions during preschool years. However, multilingual school settings, such as Luxembourg (65% of the pupils are second language learners) pose a special challenge for instruction. Non-native pre-schoolers perform lower on early mathematics tests than their age-matched peers (Bonifacci et al., 2016; Kleemans et al., 2011). This gap is most likely due to missing out on learning opportunities, as a result of lower proficiency in the language of instruction. To provide equal access to early mathematics education for all children, we developed a language-neutral early mathematics training tool, the “MaGrid”-app. This innovative training tool has been evaluated, so far, in two studies in multilingual Luxembourg. In a first study, children from five classrooms (N = 68) used the tool to train visuo-spatial abilities, an important predictor of mathematical abilities (see e.g. Mix et al., 2016), over ten weeks (2x20min/week). At post-test, significant gains in the visuo-spatial domain were observed, compared to children from “teaching-as-usual” classrooms (N = 57). In a second study, we elaborated a comprehensive language-neutral early mathematics intervention, with “MaGrid” at its core. Findings from both training studies will be presented in detail and the importance of domain-specific versus domain-general precursors, as well as practical implications, will be discussed. [less ▲]

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See detailA Scalable and Accurate Hybrid Vulnerability Analysis Framework
Thome, Julian UL

Doctoral thesis (2018)

As the Internet has become an integral part of our everyday life for activities such as e-mail, online-banking, shopping, entertainment, etc., vulnerabilities in Web software arguably have greater impact ... [more ▼]

As the Internet has become an integral part of our everyday life for activities such as e-mail, online-banking, shopping, entertainment, etc., vulnerabilities in Web software arguably have greater impact than vulnerabilities in other types of software. Vulnerabilities in Web applications may lead to serious issues such as disclosure of confidential data, integrity violation, denial of service, loss of commercial confidence/customer trust, and threats to the continuity of business operations. For companies these issues can result in significant financial losses. The most common and serious threats for Web applications include injection vulnerabilities, where malicious input can be “injected” into the program to alter its intended behavior or the one of another system. These vulnerabilities can cause serious damage to a system and its users. For example, an attacker could compromise the systems underlying the application or gain access to a database containing sensitive information. The goal of this thesis is to provide a scalable approach, based on symbolic execution and constraint solving, which aims to effectively find injection vulnerabilities in the server-side code of Java Web applications and which generates no or few false alarms, minimizes false negatives, overcomes the path explosion problem and enables the solving of complex constraints. [less ▲]

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See detailConstructive Interference for Generic Constellations
Haqiqatnejad, Alireza UL; Kayhan, Farbod UL; Ottersten, Björn UL

in IEEE Signal Processing Letters (2018), 25(4), 586-590

In this letter, we investigate optimal and relaxed constructive interference regions (CIR) for the symbol-level precoding (SLP) problem in the downlink of a multiuser multiple-input single-output (MISO ... [more ▼]

In this letter, we investigate optimal and relaxed constructive interference regions (CIR) for the symbol-level precoding (SLP) problem in the downlink of a multiuser multiple-input single-output (MISO) channel.We define two types of CIRs, namely, distance preserving CIR (DPCIR) and union bound CIR (UBCIR) for any given constellation shape and size. We then provide a systematic way to describe these regions as convex sets. Using the definitions of DPCIR and UBCIR, we show that the SLP power minimization problem, minimizing either sum or peak (per-antenna) transmit power, can always be formulated as a convex optimization problem. Our results indicate that these regions allow further reduction of the transmit power compared to the current state of the art without increasing the computational complexity at the transmitter or receiver. [less ▲]

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See detailFallstudie Großherzogtum Luxemburg
Decoville, Antoine; Feltgen, Valerie; Klein, Olivier et al

in Arch + (2018), 231

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See detailSynthesis, theoretical and experimental characterisation of thin film Cu2Sn1-xGexS3 ternary alloys (x = 0 to 1): Homogeneous intermixing of Sn and Ge
Robert, Erika UL; Gunder, René; De Wild, Jessica UL et al

in Acta Materialia (2018), 151

Cu2Sn1-xGexS3 is a p-type semiconductor alloy currently investigated for use as an absorber layer in thin film solar cells. The aim of this study is to investigate the properties of this alloy in thin ... [more ▼]

Cu2Sn1-xGexS3 is a p-type semiconductor alloy currently investigated for use as an absorber layer in thin film solar cells. The aim of this study is to investigate the properties of this alloy in thin film form in order to establish relationships between group IV composition and structural, vibrational and opto-electronic properties. Seven single phase Cu2Sn1-xGexS3 films are prepared from x ¼ 0 to 1, showing a uniform distribution of Ge and Sn laterally and in depth. The films all show a monoclinic crystal structure. The lattice parameters are extracted using Le Bail refinement and show a linear decrease with increasing Ge content. Using density-functional theory with hybrid functionals, we calculate the Raman active phonon frequencies of Cu2SnS3 and Cu2GeS3. For the alloyed compounds, we use a virtual atom approximation. The shift of the main Raman peak from x ¼ 0 to x ¼ 1 can be explained as being half due to the change in atomic masses and half being due to the different bond strength. The bandgaps of the alloys are extracted from photoluminescence measurements and increase linearly from about 0.90 to 1.56 eV with increasing Ge. The net acceptor density of all films is around 1018 cm 3. These analyses have established that the alloy forms a solid solution over the entire composition range meaning that intentional band gap grading should be possible for future absorber layers. The linear variation of the unit cell parameters and the band gap with group IV content allows composition determination by scattering or optical measurements. Further research is required to reduce the doping density by two orders of magnitude in order to improve the current collection within a solar cell device structure. [less ▲]

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See detailPathologies of Empathy: Kant, Polidori, Hoffmann
Kohns, Oliver UL

Scientific Conference (2018, April)

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See detailNon-Negative Paratuck2 Tensor Decomposition Combined to LSTM Network for Smart Contracts Profiling
Charlier, Jérémy Henri J. UL; State, Radu UL

in International Journal of Computer & Software Engineering (2018), 3(1),

Background: Past few months have seen the rise of blockchain and cryptocurrencies. In this context, the Ethereum platform, an open-source blockchain-based platform using Ether cryptocurrency, has been ... [more ▼]

Background: Past few months have seen the rise of blockchain and cryptocurrencies. In this context, the Ethereum platform, an open-source blockchain-based platform using Ether cryptocurrency, has been designed to use smart contracts programs. These are self-executing blockchain contracts. Due to their high volume of transactions, analyzing their behavior is very challenging. We address this challenge in our paper. Methods: We develop for this purpose an innovative approach based on the non-negative tensor decomposition Paratuck2 combined with long short-term memory. The objective is to assess if predictive analysis can forecast smart contracts activities over time. Three statistical tests are performed on the predictive analytics, the mean absolute percentage error, the mean directional accuracy and the Jaccard distance. Results: Among dozens of GB of transactions, the Paratuck2 tensor decomposition allows asymmetric modeling of the smart contracts. Furthermore, it highlights time dependent latent groups. The latent activities are modeled by the long short term memory network for predictive analytics. The highly accurate predictions underline the accuracy of the method and show that blockchain activities are not pure randomness. Conclusion: Herein, we are able to detect the most active contracts, and predict their behavior. In the context of future regulations, our approach opens new perspective for monitoring blockchain activities. [less ▲]

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See detailGesellschaftliche Integration und soziale Kohäsion in Luxemburg – zu den Herausforderungen in einer heterogenen Gesellschaft
Biewers, Sandra UL; Willems, Helmut UL

in Georges, Nathalie; Schronen, Danielle; Urbé, Robert (Eds.) Sozialalmanach 2018 - D’sozial Kohesioun um Spill (2018)

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See detailUn crépuscule pour réveiller l'histoire
Scuto, Denis UL

Article for general public (2018)

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See detailContested Autonomies: French University Governance and its Discontents
Harmsen, Robert UL

Scientific Conference (2018, March 28)

In the past decade, the governance of French universities has seen substantial changes in line with developments elsewhere in Europe. Engaging in an ‘autonomy/accountability two-step’, French universities ... [more ▼]

In the past decade, the governance of French universities has seen substantial changes in line with developments elsewhere in Europe. Engaging in an ‘autonomy/accountability two-step’, French universities have been granted a significantly higher degree of organisational autonomy while at the same time becoming subject to a widening set of external accountability measures. The French case nonetheless presents interesting specificities stemming particularly from the absence of a strong tradition of institutional-level university autonomy. The present paper explores current reforms against the background of this distinctive historical tradition, probing the mediation of ‘global scripts’ by ‘national filters’. After setting out the broad contours of the historical model, successive sections then survey the 2007 Law on the Liberty and Responsibility of Universities, the 2013 Fioraso Law, and the possible direction of policy under the Macron presidency. The concluding section situates French developments relative to wider trends in terms suggestive of a forward research agenda. [less ▲]

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See detailÊtre d'ailleurs en temps de guerre
Scuto, Denis UL

Article for general public (2018)

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See detailRudolf Seidel, Léon Metz et la Halle des soufflantes
Scuto, Denis UL

Article for general public (2018)

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See detailSpaces – different modes of space in towns
Pauly, Michel UL; Scheutz, Martin

in Fray, Jean-Luc; Pauly, Michel; Pinheiro, Magda (Eds.) et al Urban Spaces and the complexity of Cities (2018)

introduction to the volume stressing the importance of the spatial turn in urban history and the complexity of towns

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See detailSecretion of the Phosphorylated Form of S100A9 from Neutrophils Is Essential for the Proinflammatory Functions of Extracellular S100A8/A9.
Schenten, Veronique; Plancon, Sebastien; Jung, Nicolas UL et al

in Frontiers in immunology (2018), 9

S100A8 and S100A9 are members of the S100 family of cytoplasmic EF-hand Ca(2+)-binding proteins and are abundantly expressed in the cytosol of neutrophils. In addition to their intracellular roles, S100A8 ... [more ▼]

S100A8 and S100A9 are members of the S100 family of cytoplasmic EF-hand Ca(2+)-binding proteins and are abundantly expressed in the cytosol of neutrophils. In addition to their intracellular roles, S100A8/A9 can be secreted in the extracellular environment and are considered as alarmins able to amplify the inflammatory response. The intracellular activity of S100A8/A9 was shown to be regulated by S100A9 phosphorylation, but the importance of this phosphorylation on the extracellular activity of S100A8/A9 has not yet been extensively studied. Our work focuses on the impact of the phosphorylation state of secreted S100A9 on the proinflammatory function of neutrophils. In a first step, we characterized the secretion of S100A8/A9 in different stimulatory conditions and investigated the phosphorylation state of secreted S100A9. Our results on neutrophil-like differentiated HL-60 (dHL-60) cells and purified human neutrophils showed a time-dependent secretion of S100A8/A9 when induced by phorbol 12-myristoyl 13-acetate and this secreted S100A9 was found in a phosphorylated form. Second, we evaluated the impact of this phosphorylation on proinflammatory cytokine expression and secretion in dHL-60 cells. Time course experiments with purified unphosphorylated or phosphorylated S100A8/A9 were performed and the expression and secretion levels of interleukin (IL)-1alpha, IL-1beta, IL-6, tumor necrosis factor alpha, CCL2, CCL3, CCL4, and CXCL8 were measured by real-time PCR and cytometry bead array, respectively. Our results demonstrate that only the phosphorylated form of the complex induces proinflammatory cytokine expression and secretion. For the first time, we provide evidence that S100A8/PhosphoS100A9 is inducing cytokine secretion through toll-like receptor 4 signaling. [less ▲]

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See detailA Simple Engineering Soil Surface Vibration Prediction Method
Macijauskas, Darius UL; Van Baars, Stefan UL

in Civil Engineering Research Journal (2018), 4(2),

In urban areas where the infrastructure is dense and construction of new structures is near existing and sensitive buildings, frequently vibrations, caused by human activities, occur. Generated waves in ... [more ▼]

In urban areas where the infrastructure is dense and construction of new structures is near existing and sensitive buildings, frequently vibrations, caused by human activities, occur. Generated waves in the soil may adversely affect surrounding buildings. These vibrations have to be predicted a priori by using currently available knowledge of the soil dynamics. In order to make a good prediction of the soil surface vibration, it is necessary to perform calculations with a Finite Element Method (FEM). The disadvantages of the FEM are that this requires a special software package and a long time for the modelling and calculations. Therefore, it would be very useful to derive a simple model for engineering purposes, which could be used to predict geotechnical vibrations close to the source, without the need of special software and long calculations. Such a method is proposed in this article. This method is validated by a vibration test performed on a peaty site in the Netherlands. The predictions made with this method, have been compared with both the field measurements and the FEM calculations. The comparison proves that by using the presented vibration prediction method, the vibrations can be predicted as accurate as with the FEM. [less ▲]

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See detailEU 'Horizontal' Report
Ligeti, Katalin UL; Marletta, Angelo UL

in Vervaele, John; Simonato, Michele; Luchtman, Michiel (Eds.) Exchange of information with EU and national enforcement authorities. Improving OLAF legislative framework through a comparison with other EU authorities (ECN/ESMA/ECB) (2018)

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See detailFunds and EU Tax Directives
Pantazatou, Aikaterini UL

in Haslehner, Werner (Ed.) Investment Fund Taxation (2018)

Detailed reference viewed: 21 (1 UL)