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See detailThe Multi-Generation Repackaging Hypothesis
Li, Li UL; Bissyande, Tegawendé François D Assise UL; Bartel, Alexandre UL et al

Poster (2017, May)

App repackaging is a common threat in the Android ecosystem. To face this threat, the literature now includes a large body of work proposing approaches for identifying repackaged apps. Unfortunately ... [more ▼]

App repackaging is a common threat in the Android ecosystem. To face this threat, the literature now includes a large body of work proposing approaches for identifying repackaged apps. Unfortunately, although most research involves pairwise similarity comparison to distinguish repackaged apps from their “original” counterparts, no work has considered the threat to validity of not being able to discover the true original apps. We provide in this paper preliminary insights of an investigation into the Multi-Generation Repackaging Hypothesis: is the original in a repackaging process the outcome of a previous repackaging process? Leveraging the Androzoo dataset of over 5 million Android apps, we validate this hypothesis in the wild, calling upon the community to take this threat into account in new solutions for repackaged app detection. [less ▲]

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See detailUnderstanding Android App Piggybacking
Li, Li UL; Li, Daoyuan UL; Bissyande, Tegawendé François D Assise UL et al

Poster (2017, May)

The Android packaging model offers adequate opportunities for attackers to inject malicious code into popular benign apps, attempting to develop new malicious apps that can then be easily spread to a ... [more ▼]

The Android packaging model offers adequate opportunities for attackers to inject malicious code into popular benign apps, attempting to develop new malicious apps that can then be easily spread to a large user base. Despite the fact that the literature has already presented a number of tools to detect piggybacked apps, there is still lacking a comprehensive investigation on the piggybacking processes. To fill this gap, in this work, we collect a large set of benign/piggybacked app pairs that can be taken as benchmark apps for further investigation. We manually look into these benchmark pairs for understanding the characteristics of piggybacking apps and eventually we report 20 interesting findings. We expect these findings to initiate new research directions such as practical and scalable piggybacked app detection, explainable malware detection, and malicious code location. [less ▲]

Detailed reference viewed: 30 (4 UL)
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See detailThe influence of Forced Answering on response behavior in Online Surveys: A reactance effect?
Sischka, Philipp UL; Mergener, Alexandra; Neufang, Kristina Marliese et al

Poster (2017, March 16)

Relevance: Recent studies have shown that the use of the forced answering (FA) option in online surveys results in reduced data. They especially examined that forcing respondents to answer questions in ... [more ▼]

Relevance: Recent studies have shown that the use of the forced answering (FA) option in online surveys results in reduced data. They especially examined that forcing respondents to answer questions in order to proceed through the questionnaire leads to higher dropout rates and lower answer quality. However, no study researched the psychological mechanism behind the correlation of FA on dropout and data quality before. This response behavior has often been interpreted as psychological reactance reaction. So, the Psychological Reactance Theory (PRT) predicts that reactance appears when an individuals’ freedom is threatened and cannot be directly restored. Reactance describes the motivation to restore this loss of freedom. Respondents could experience FA as a loss of freedom, as (s)he is denied the choice to leave a question unanswered. According to PRT, possible reactions in this situation might be to quit survey participation, to fake answers or to show satisficing tendencies. Research content: This study explores the psychological mechanism that effects response behavior in FA condition (compared to non-FA- condition). Our major hypothesis is that forcing respondents to answer will cause reactance, which turns into increasing dropout rates, decreasing answer quality and a satisficing behavior. Methods and Data: We used an online survey-experiment with two conditions (forced and non-forced answering instructions). The sample consists of 914 participants. Throughout the whole questionnaire, a dropout button was implemented on each page. In both conditions, this button led to the same page that fully compliant participants reached at the end of the questionnaire. Reactance was measured with a self-constructed four-item reactance scale. To determine answer quality, we used self-report for faking as well as the analysis of answers to open ended questions. Results: Zero-order effects showed that FA increased state reactance and questionnaire dropout as well as it reduced answer length in open-ended questions. Mediation analysis (Condition -> state reactance -> dropout/answer quality) supported the hypothesis of reactance as an underlying psychological mechanism behind negative FA effects on data quality. Added Value: This is the first study which offers statistical evidence for the often proposed reactance effect influencing response behavior. This offers a base for a deeper psychological reflection of the use of the FA-option. [less ▲]

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See detailA Change Management Approach in Product Lines for Use Case-Driven Development and Testing
Hajri, Ines UL; Göknil, Arda UL; Briand, Lionel UL

Poster (2017, March)

In this paper, driven by industrial needs, we present a change management approach for product lines within the context of use case-driven development and testing. As part of the approach, we first ... [more ▼]

In this paper, driven by industrial needs, we present a change management approach for product lines within the context of use case-driven development and testing. As part of the approach, we first provide a modeling method to support variability modeling in Product Line (PL) use case diagrams, specifications, and domain models, intentionally avoiding any reliance on feature models and thus avoiding unnecessary modeling and traceability overhead. Then, we introduce a use case-driven configuration approach based on the proposed modeling method to automatically generate Product Specific (PS) use case and domain models from the PL models and configuration decisions. Building on this, we provide a change impact analysis approach for evolving configuration decisions in PL use case models. In addition, we plan to develop a change impact analysis approach for evolving PL use case models and an automated regression test selection technique for evolving configuration decisions and PL models. [less ▲]

Detailed reference viewed: 23 (14 UL)
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See detailSingle station Monitoring of Volcanoes Using Seismic ambient noise
De Plaen, Raphaël UL; Lecocq, Thomas; Caudron, Corentin et al

Poster (2016, December 16)

Detailed reference viewed: 16 (2 UL)
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See detailImage to analysis pipeline: single and double balloons kyphoplasty
Baroli, Davide UL; Hauseux, Paul UL; Hale, Jack UL et al

Poster (2016, December 12)

In this work, we present a semi-automatic pipeline from image to simulation of a patient fractured vertebra after the kyphoplastic augmentation with two balloons. In this procedure, the CT-scan medical ... [more ▼]

In this work, we present a semi-automatic pipeline from image to simulation of a patient fractured vertebra after the kyphoplastic augmentation with two balloons. In this procedure, the CT-scan medical image are pre-processed using open-source software Slice3D for segmentation and 3D reconstruction operation. Then, using geometric processing the 3D surface geometry is enhanced to avoid degenerate element and trigging phenomena on vertebra and cement area. We perform a finite element analysis to evaluate the risk of subsequent vertebral fracture. Finally using Monte-Carlo technique, we assess the propagation of uncertainty of material parameter on the evaluation of this risk. Based on the developed semi-automatic pipelines, it is possible to perform a patient-specific simulation that assesses the successful of kyphoplasty operation. [less ▲]

Detailed reference viewed: 67 (22 UL)
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See detailBayesian inference for parameter identification in computational mechanics
Rappel, Hussein UL; Beex, Lars UL; Hale, Jack UL et al

Poster (2016, December 12)

Detailed reference viewed: 42 (3 UL)
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See detailOn the Impact of Multi-GNSS Solutions on Satellite Products and Positioning
Abraha, Kibrom Ebuy UL; Teferle, Felix Norman UL; Hunegnaw, Addisu UL et al

Poster (2016, December 12)

In Global Navigation Satellite System (GNSS) coordinate time series unrecognised errors and un-modelled (periodic) effects may bias non-linear motions induced by geophysical signals. Those spurious ... [more ▼]

In Global Navigation Satellite System (GNSS) coordinate time series unrecognised errors and un-modelled (periodic) effects may bias non-linear motions induced by geophysical signals. Those spurious signals can be caused either due to un-modelled long periodic signals or propagation of sub-daily signals into the time series. Understanding and mitigating these errors is vital to reduce biases and on revealing subtle geophysical signals. Mostly, the spurious signals are caused by unmodelled errors which occur due to the draconitic years, satellite ground repeats and absorption into resonant GNSS orbits. Accordingly, different features can be observed in GNSS-derived products from different single-GNSS or combined-GNSS solutions. To assess the nature of periodic signals on station coordinate time series Precise Point Positioning (PPP) solutions are generated using the Bernese GNSS Software V5.2. The solutions consider only GPS, only GLONASS or combined GPS+GLONASS (GNSS) observations. We assess the periodic signals of station coordinates computed using the combined International GNSS Service (IGS) and four of its Analysis Centers (ACs) products. [less ▲]

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See detailReal-time error control for surgical simulation
Bui, Huu Phuoc UL; Tomar, Satyendra UL; Courtecuisse, Hadrien et al

Poster (2016, December 12)

Objective: To present the first real-time a posteriori error-driven adaptive finite element approach for real-time simulation and to demonstrate the method on a needle insertion problem. Methods: We use ... [more ▼]

Objective: To present the first real-time a posteriori error-driven adaptive finite element approach for real-time simulation and to demonstrate the method on a needle insertion problem. Methods: We use corotational elasticity and a frictional needle/tissue interaction model based on friction. The problem is solved using finite elements within SOFA. The refinement strategy relies upon a hexahedron-based finite element method, combined with a posteriori error estimation driven local $h$-refinement, for simulating soft tissue deformation. Results: We control the local and global error level in the mechanical fields (e.g. displacement or stresses) during the simulation. We show the convergence of the algorithm on academic examples, and demonstrate its practical usability on a percutaneous procedure involving needle insertion in a liver. For the latter case, we compare the force displacement curves obtained from the proposed adaptive algorithm with that obtained from a uniform refinement approach. Conclusions: Error control guarantees that a tolerable error level is not exceeded during the simulations. Local mesh refinement accelerates simulations. Significance: Our work provides a first step to discriminate between discretization error and modeling error by providing a robust quantification of discretization error during simulations. [less ▲]

Detailed reference viewed: 113 (18 UL)
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See detailElastography under uncertainty
Hale, Jack UL; Farrell, Patrick; Bordas, Stéphane UL

Poster (2016, December 12)

Detailed reference viewed: 62 (9 UL)
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See detailError analysis of Tide Gauge Benchmark Monitoring (TIGA) Analysis Center stacked solutions
Hunegnaw, Addisu UL; Teferle, Felix Norman UL; Abraha, Kibrom Ebuy UL et al

Poster (2016, December 12)

In 2013 the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) started their reprocessing campaign, which proposes to re-analyze all relevant Global Positioning ... [more ▼]

In 2013 the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) started their reprocessing campaign, which proposes to re-analyze all relevant Global Positioning System (GPS) observations from 1995 to the end of 2013. This re-processed dataset will provide high quality estimates of land motions, enabling regional and global high-precision geophysical/geodetic studies. Several of the individual TIGA Analysis Centers (TACs) have completed processing the full history of GPS observations recorded by the IGS global network, as well as, many other GPS stations at or close to tide gauges, which are available from the TIGA data center at the University of La Rochelle (www.sonel.org). The TAC solutions contain a total of over 700 stations. This study focuses on the evaluations of any systematic error present in the three TIGA analysis center (TAC) SINEX solutions: the British Isles continuous GNSS Facility – University of Luxembourg consortium (BLT), the GeoForschungsZentrum (GFZ) Potsdam, and of the University of La Rochelle (ULR). We have analyzed the residual position time series of the individual TAC a combination of automatic and manual discontinuity identification, applying a post-seismic deformation model adopted from ITRF2014 for those stations that are affected by earthquakes, followed by the stacking of the daily solution of the individual TAC into a long term linear frame. We have carried out the error analysis using the Combination and Analysis of Terrestrial Reference Frame (CATREF) software package. The TIGA Combination Centre (TCC) at the University of Luxembourg (UL) is responsible for providing a combined solution with a global set of vertical land movement estimates. [less ▲]

Detailed reference viewed: 53 (18 UL)
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See detailPoster: LuST-LTE: A Simulation Package for Pervasive Vehicular Connectivity
Derrmann, Thierry UL; Faye, Sébastien UL; Frank, Raphaël UL et al

Poster (2016, December 08)

Recent technological advances in communication technology have provided new ways to understand human mobility. Connected vehicles with their rising market penetration are particularly representative of ... [more ▼]

Recent technological advances in communication technology have provided new ways to understand human mobility. Connected vehicles with their rising market penetration are particularly representative of this trend. They become increasingly interesting, not only as sensors, but also as participants in Intelligent Transportation System (ITS) applications. More specifically, their pervasive connectivity to cellular networks enables them as passive and active sensing units. In this paper, we introduce LuST-LTE, a package of open-source simulation tools that allows the simulation of vehicular traffic along with pervasive LTE connectivity. [less ▲]

Detailed reference viewed: 47 (8 UL)
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See detailUncertainty quantification for soft tissue biomechanics
Hauseux, Paul UL; Hale, Jack UL; Bordas, Stéphane UL

Poster (2016, December)

Detailed reference viewed: 76 (7 UL)
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See detailGame-Theoretic Framework for Integrity Verification in Computation Outsourcing
Pejo, Balazs UL; Tang, Qiang

Poster (2016, November 03)

Detailed reference viewed: 18 (4 UL)
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See detailFacteurs psychologiques, cognitifs et les influences contextuelles dans la douleur et la souffrance liée à la douleur
Bustan, Smadar; Gonzalez-Roldan, Ana Maria; Schommer, Christoph UL et al

Poster (2016, November)

Detailed reference viewed: 12 (2 UL)
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See detailEfficient Learning of Communication Profiles from IP Flow Records
Hammerschmidt, Christian UL; Marchal, Samuel; Pellegrino, Gaetano et al

Poster (2016, November)

The task of network traffic monitoring has evolved drastically with the ever-increasing amount of data flowing in large scale networks. The automated analysis of this tremendous source of information ... [more ▼]

The task of network traffic monitoring has evolved drastically with the ever-increasing amount of data flowing in large scale networks. The automated analysis of this tremendous source of information often comes with using simpler models on aggregated data (e.g. IP flow records) due to time and space constraints. A step towards utilizing IP flow records more effectively are stream learning techniques. We propose a method to collect a limited yet relevant amount of data in order to learn a class of complex models, finite state machines, in real-time. These machines are used as communication profiles to fingerprint, identify or classify hosts and services and offer high detection rates while requiring less training data and thus being faster to compute than simple models. [less ▲]

Detailed reference viewed: 68 (4 UL)
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See detailPOSTER: Fingerprinting Tor Hidden Services
Mitseva, Asya UL; Panchenko, Andriy UL; Lanze, Fabian et al

Poster (2016, October)

Detailed reference viewed: 83 (14 UL)
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See detailBehavioral Clustering of Non-Stationary IP Flow Record Data
Hammerschmidt, Christian UL; Marchal, Samuel; State, Radu UL et al

Poster (2016, October)

Detailed reference viewed: 55 (4 UL)
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See detailDifferent aspects of spatial skills and their relation to early mathematics
Cornu, Véronique UL; Hornung, Caroline; Schiltz, Christine UL et al

Poster (2016, September 29)

We aimed at investigating the predictive role of spatial skills for arithmetic and number line estimation in kindergarten children (N = 125). Several studies highlighted the relation between spatial ... [more ▼]

We aimed at investigating the predictive role of spatial skills for arithmetic and number line estimation in kindergarten children (N = 125). Several studies highlighted the relation between spatial skills and mathematics. However, due to their non-unitary nature, different aspects of spatial skills need to be differentiated to clarify the relative importance of different aspects of spatial skills for mathematics. In the present study, at time 1, a spatial perception task, a spatial visualization task and visuo-motor integration task were administered to assess different aspects of spatial skills. Furthermore we assessed domain-specific skills and verbal domain-general skills. Four months later, the same children performed an arithmetic task and a number line estimation task to evaluate how the abilities measured at time 1 predict early mathematics. Hierarchical regression modelling revealed that children’s performance on the spatial perception task was predictive of their performance in both arithmetic and number line estimation, whereas visuo-motor integration and knowledge of the Arabic numerals significantly predicted arithmetic. The predictive relation between spatial perception and arithmetic was partially mediated by the number line estimation task. Our findings emphasize the role of spatial skills, notably spatial perception, in mathematical development. These results reveal the importance to differentiate within the construct of spatial skills when studying their role in numerical development. The development and implementation of pre-school interventions fostering children’s spatial perception and visuo-motor integration might thus be a promising approach for providing children with a sound foundation for later mathematical learning. [less ▲]

Detailed reference viewed: 73 (17 UL)
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See detailCoP Luxembourg
Böwen, Petra UL; Dujardin, Céline UL; Pissinger, Simone

Poster (2016, September 05)

Detailed reference viewed: 43 (5 UL)
See detailEnergy fractionalization after single electron injection into an interacting helical liquid
Calzona, Alessio UL; Acciai, Matteo; Carrega, Matteo et al

Poster (2016, September)

Detailed reference viewed: 8 (1 UL)
See detailGeneric Helical Liquids: Theory & Applications
Rod, Alexia UL; Dolcetto, Giacomo UL; Rachel, Stephan et al

Poster (2016, August 23)

Detailed reference viewed: 9 (5 UL)
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See detailOn the Properties of Zenith Total Delay Time Series from Reprocessed GPS Solutions
Klos, Anna; Teferle, Felix Norman UL; Hunegnaw, Addisu UL et al

Poster (2016, July 29)

Global Positioning System observations from stations in regional and global networks have proven to sense the conditions of the atmosphere, especially the water vapour content of the troposphere. Zenith ... [more ▼]

Global Positioning System observations from stations in regional and global networks have proven to sense the conditions of the atmosphere, especially the water vapour content of the troposphere. Zenith Total Delay (ZTD) derived during the processing of GPS data is a measure of the total atmospheric delay along the signal path between satellite and receiver antennas and arises mostly from the hydrostatic and wet parts of the atmosphere. Having taken surface pressure and temperature into account, ZTD can be converted into an estimate of the Integrated Water Vapour (IWV) content of the atmosphere, which when derived from homogenously reprocessed GPS observations, is emerging as an important parameter in the monitoring of climate change. Especially, the long-term trend and variations in IWV together with their associated uncertainties are of high interest as atmospheric water vapour is the dominant greenhouse gas. To date the trend estimates and their uncertainties are widely determined with assumption that the stochastic properties of the time series follow a random, ie. white noise, process. However, if ZTD and IWV are directly linked to climate processes, one would expect that the underlying noise process has similar character to that found in other climate parameters, which have been modelled by means of an autoregressive process. If this proves to be true, the trend estimates and their uncertainties in ZTD and IWV may have been underestimated up to this day of an order of magnitude. In this research, we examine the properties of both deterministic and stochastic parameters of the ZTDs that were estimated by the consortium of the British Isles continuous GNSS Facility (BIGF) and the University of Luxembourg TIGA Analysis Centres (BLT) for GPS data collected by a global tracking network of more than 700 stations (repro2 solution). The analysis has been started with the homogenisation of the ZTD time series, which is an important task to provide homogeneity over the long-term. Here we used all previously reported discontinuities for a single station along with those added after manually inspecting the time series. This procedure did lead to a total number of 2505 discontinuities for this data set. Next, all significant oscillations were identified with spectral analysis and thereafter modelled with a Least-Squares Method. The residuals were subjected to noise analysis with different stochastic models. The results showed that an autoregressive model of fourth order combined with a white noise process is the optimal model for the ZTD time series. Finally, we provide an optimum evaluation of the ZTD trends and their uncertainties for selected climate zones, which were established according to the Köppen-Geiger climate classification. [less ▲]

Detailed reference viewed: 89 (9 UL)
Peer Reviewed
See detailAnnotating and Georeferencing of Digitized Early Maps
Höhn, Winfried UL; Schommer, Christoph UL

Poster (2016, July)

Original early maps are usually only accessible for a small group of researchers and librarians because they are very old and sensitive, and could be easily destroyed. However, they are a valuable ... [more ▼]

Original early maps are usually only accessible for a small group of researchers and librarians because they are very old and sensitive, and could be easily destroyed. However, they are a valuable knowledge source for historical research, because they are also political and cultural evidences of its time. In the age of Digital Humanities, online access and information search in digitized historical documents and early maps allows people from all over the world to work with such artefacts of cultural heritage. However, the digitization solely generates images of the artefacts without any access to the semantics of the documents. [less ▲]

Detailed reference viewed: 28 (2 UL)
Peer Reviewed
See detailFatherhood Desires and Intentions: A Comparison of Childless Gay and Straight Men in Germany
Kranz, Dirk; Busch, Holger; Niepel, Christoph UL

Poster (2016, July)

Detailed reference viewed: 29 (1 UL)
Peer Reviewed
See detailEarly life adversity associates with increased depressive symptoms and few active T cells in adulthood
Elwenspoek, Martha; Schaan, Violetta UL; Hengesch, Xenia et al

Poster (2016, June)

Detailed reference viewed: 49 (6 UL)
Peer Reviewed
See detailInterventions addressing subjective well-being in ageing: Promissing approaches on individual and societal level
Boll, Thomas UL; Ferring, Dieter UL

Poster (2016, June)

Subjective well-being (SWB) in aging is important not only as an indicator of positive aging, but also because of its effects on relevant outcomes for the person (e.g., health) and the community (e.g ... [more ▼]

Subjective well-being (SWB) in aging is important not only as an indicator of positive aging, but also because of its effects on relevant outcomes for the person (e.g., health) and the community (e.g., involvements). This raises the question of how SWB of older people can be improved through interventions. Our contribution focusses on three domains for improving SWB: Optimization of resources (e.g., financial situation, autonomy), help with critical life events (e.g., widowhood, disablement), and support at the end of life. We consider reasons for optimizing SWB in these areas as well as the theoretical and empirical foundation for interventions. Among them are (1) bottom-up approaches regarding the link between domain-specific SWB (e.g., regarding health, financial situation, social relationships) and global SWB, (2) Coping approaches to critical life events frequently occuring in old age (e.g., widowhood, disablement) and (3) research on terminal decline of SWB. Against this background principal possibilities of optimizing SWB in these domains are delineated and both individual and societal (e.g., communal, national) level interventions are described. [less ▲]

Detailed reference viewed: 75 (4 UL)
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See detailDéveloppement d’un instrument de dépistage des précurseurs cognitifs pour l’apprentissage scolaire dans un contexte multilingue
Cornu, Véronique UL; Hornung, Caroline

Poster (2016, June)

Nombreuses études ont pu constater que les aptitudes et les apprentissages précoces influencent les apprentissages académiques ultérieurs. La valeur prédictive de différentes fonctions cognitives à l’âge ... [more ▼]

Nombreuses études ont pu constater que les aptitudes et les apprentissages précoces influencent les apprentissages académiques ultérieurs. La valeur prédictive de différentes fonctions cognitives à l’âge préscolaire est un sujet toujours vivement discuté. L'apprentissage des mathématiques, de la lecture et de l'écrit sont soutenues par des fonctions cognitives telles que les capacités pré-numériques, le langage, les fonctions visuo-spatiales, les fonctions exécutives dont la mémoire de travail, la vitesse de traitement et la raisonnement logique. Néanmoins, seulement peu de données scientifiques sont actuellement disponibles sur l’apport de ces différentes fonctions cognitives aux apprentissages scolaires dans un contexte multilingue comme celui du Luxembourg. Au Luxembourg environ 35 % des élèves scolarisés à l'école maternelle parlent Luxembourgeois à la maison. La plupart des enfants parlent d'autres langues voire plusieurs langues au sein de leur famille. A l'école maternelle les enfants apprennent le Luxembourgeois pendant 2-3 ans. Ensuite en 1ère année de l'enseignement fondamental primaire public, tous les enfants sont alphabétisés en Allemand. Et ce n'est qu'un an plus tard que le Français s'ajoute aux apprentissages scolaires. L'apprentissage des langues est un projet ambitieux au Luxembourg et les résultats nationaux ont montré que 42 % des élèves en 3e année primaire (CE2) n'ont malheureusement pas obtenu le niveau minimal à atteindre visé par le plan d'étude en 2013 (Hornung, Hoffmann, Lorphelin, Gamo, Ugen, Fischbach, & Martin, 2015). Le but est de développer un instrument qui s'adapte au contexte scolaire multilingue et qui permet de mesurer ces précurseurs cognitifs d’une manière valide. Ce projet vise à mieux comprendre comment différentes capacités cognitives précoces influencent les différents apprentissages scolaires dans un contexte scolaire multilingue chez l’enfant de 4 à 7 ans et les résultats de ce projet pourront servir comme base pour pouvoir développer des outils d’intervention visant à stimuler le développement de ces précurseurs dans un contexte multilingue. La présente batterie de tests inclut plusieurs épreuves brèves individuelles pour évaluer les performances numériques et visuo-spatiales, la capacité d'inhibition verbale et d'inhibition motrice, l'empan de la mémoire de travail verbale et visuo-spatiale, la flexibilité verbale, la vitesse de traitement, la conscience phonologique, la discrimination visuelle et le vocabulaire expressif chez l’enfant de 4 à 7 ans. Ces petites épreuves visent à évaluer ces différents précurseurs cognitifs de l’apprentissage scolaire et elles ont été développées et adaptées spécifiquement pour le contexte préscolaire suite à un pilotage avec la population cible. Dans une première phase, les relations entre ces différentes épreuves seront étudiées pour pouvoir concrétiser notre compréhension sur l’interrelation de ces différents précurseurs cognitifs. Afin de pouvoir évaluer la valeur prédictive de ces différentes fonctions cognitives, une approche longitudinale est visée. Nous avons prévu de mettre en relation les résultats obtenus au préscolaire (Phase I) avec les résultats de ces mêmes enfants obtenus lors des «épreuves standardisées» du monitoring scolaire au Luxembourg, réalisées en première année de l’école primaire (CP en France) (Phase II). [less ▲]

Detailed reference viewed: 86 (8 UL)
See detailChemical stability of the Cu2SnS3/Mo interface
De Wild, Jessica UL; Robert, Erika UL; Dale, Phillip UL

Poster (2016, June)

Detailed reference viewed: 58 (7 UL)
Peer Reviewed
See detailDifférences inter‐ et intraindividuelles en besoin de cognition
Keller, Ulrich UL; Strobel, Anja; Martin, Romain UL et al

Poster (2016, June)

Detailed reference viewed: 63 (9 UL)
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See detailA PRELIMINARY STUDY ON THE STABILITY OF PARTICLE LADEN JETS THROUGH A FULLY COUPLED CFD-DEM SOLVER
Peters, Bernhard UL; Pozzetti, Gabriele UL

Poster (2016, May 22)

Jets are widely used in engineering applications. In material machinery, hydro-transportation systems as well as in chemical industry it is common to deal with a dispersed solid phase interacting with the ... [more ▼]

Jets are widely used in engineering applications. In material machinery, hydro-transportation systems as well as in chemical industry it is common to deal with a dispersed solid phase interacting with the jet, and therefore creating a so-called slurry-jet or particle-laden jet. The stability of a jet is a key issue for many of these processes, still the underlying physics of this turbulent multiphase flow is highly complicated. Conventional CFD approaches have been proven satisfying for the study of the stability of two-phase jets. When a solid dispersed phase is present in the system, the stability problem gets more complicated and dependent on the solid phase dynamic. A possible solution for the problem is to extend the CFD solver capability through a correct coupling with a DEM solver. In this work a preliminary investigation on the potentialities of this kind of approach is presented and compared with a pure CFD approach. In particular the effect of the presence of differently sized particles in the jet is outlined and the influence of particle properties and concentration is investigated. Finally some considerations about the computational cost of different methods are proposed. The fluid phases are solved through an Eulerian finite volume (FV) multiphase solver based on the OpenFoam® libraries, and coupled with the XDEM code in order to treat the dispersed phase in a Lagrangian way. [less ▲]

Detailed reference viewed: 70 (10 UL)
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See detailStudy of space weather impact on Antarctica ionosphere from GNNS data
Bergeot, Nicolas; Chevalier, J.-M.; Bruyninx, Carine et al

Poster (2016, April 29)

The impact of solar activity on the ionosphere at polar latitudes is not well known compare to low and mid-latitudes due to lack of experimental observations, especially over Antarctica. Consequently, one ... [more ▼]

The impact of solar activity on the ionosphere at polar latitudes is not well known compare to low and mid-latitudes due to lack of experimental observations, especially over Antarctica. Consequently, one of the present challenges of the Space Weather community is to better characterize (1) the climatological behavior of the polar ionosphere in response to variations of the solar activity and (2) the different response of the ionosphere at high latitudes during extreme solar events and geomagnetic storms. For that, the combination of GNSS measurements (e.g. GPS, GLONASS and Galileo) on two separate frequencies allows determining the ionospheric delay between a ground receiver and a satellite. This delay is function of the integrated number of electrons encountered in the ionosphere along the signal ray path, called the Total Electron Content (TEC). It is thus possible to study the behavior of ionospheric TEC at different time and spatial scales from the observations of a network of permanent GNSS stations. In the frame of GIANT-LISSA and IceCon projects we installed since 2009 five GNSS stations around the Princess Elisabeth station. We used these stations additionally to other stations from the IGS global network to estimate the ionospheric TEC at different locations over Antarctica. This study presents this regional data set during different solar activity levels and discusses the different climatological behaviors identified in the ionosphere at these high latitudes. Finally, we will show few examples of typical TEC disturbances observed during extreme solar events. [less ▲]

Detailed reference viewed: 92 (12 UL)
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See detailCombination of Tide Gauge Benchmark Monitoring (TIGA) Analysis Center from repro2 solutions
Hunegnaw, Addisu UL; Teferle, Felix Norman UL

Poster (2016, April 19)

Recently the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) has completed their repro2 solutions by re-analyzing the full history of all relevant Global ... [more ▼]

Recently the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) has completed their repro2 solutions by re-analyzing the full history of all relevant Global Positioning System (GPS) observations from 1995 to 2015. This re-processed data set will provide high-quality estimates of vertical land movements for more than 700 stations, enabling regional and global high-precision geophysical/geodetic studies. All the TIGA Analysis Centres (TACs) have processed the observations recorded by GPS stations at or close to tide gauges, which are available from the TIGA Data Center at the University of La Rochelle (www.sonel.org) besides those of the global IGS core network used for its reference frame implementations. Following the recent improvements in processing models, strategies (http://acc.igs.org/reprocess2.html), this is the first complete reprocessing attempt by the TIGA WG to provide homogeneous position time series relevant to sea level changes. In this study we report on a first multi-year daily combined solution from the TIGA Combination Centre (TCC) at the University of Luxembourg (UL) with respect to the latest International Terrestrial Reference Frame (ITRF2014). Using GLOBK combination software package, we have computed a first daily combined solution from TAC solutions already available to the TIGA WG. These combinations allow an evaluation any effects of the individual TAC parameters and their influences on the combined solution with respect to the latest ITRF2014. Some results of the UL TIGA multi-year combinations in terms of geocentric sea level changes will be presented and discussedd [less ▲]

Detailed reference viewed: 58 (6 UL)
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Peer Reviewed
See detailApplications of the CPAL language to model, simulate and program Cyber-Physical Systems
Fejoz, Loïc; Navet, Nicolas UL; Sundharam, Sakthivel Manikandan UL et al

Poster (2016, April 12)

CPAL is a new language to model, simulate, verify and program Cyber-Physical Systems (CPS). CPAL serves to describe both the functional behaviour of activities (i.e., the code of the function itself) as ... [more ▼]

CPAL is a new language to model, simulate, verify and program Cyber-Physical Systems (CPS). CPAL serves to describe both the functional behaviour of activities (i.e., the code of the function itself) as well as the functional architecture of the system (i.e., the set of functions, how they are activated, and the data flows among the functions). CPAL is meant to support two use-cases. Firstly, CPAL is a development and design-space exploration environment for CPS with main features being the formal description, the editing, graphical representation and simulation of CPS models. Secondly, CPAL is a real-time execution platform. The vision behind CPAL is that a model is executed and verified in simulation mode on a workstation and the same model can be later run on an embedded board with a timing-equivalent run-time behaviour. The design and development of CPAL have been organized around a set of realistic case-studies that will be demonstrated during the demo session. [less ▲]

Detailed reference viewed: 81 (52 UL)
See detailThe Combined Effect of Periodic Signals and Noise on the Dilution of Precision of GNSS Station Velocity Uncertainties
Klos, Anna; Olivares Pulido, German UL; Teferle, Felix Norman UL et al

Poster (2016, April 05)

Station velocity uncertainties determined from a series of Global Navigation Satellite System (GNSS) position estimates depend on both the deterministic and stochastic models applied to the time series ... [more ▼]

Station velocity uncertainties determined from a series of Global Navigation Satellite System (GNSS) position estimates depend on both the deterministic and stochastic models applied to the time series. While the deterministic model generally includes parameters for a linear and several periodic terms, the stochastic model is a representation of the noise character of the time series in form of a power-law process. For both of these models the optimal model may vary from one time series to another while the models also depend, to some degree, on each other. In the past various power-law processes have been shown to fit the time series and the sources for the apparent temporally-correlated noise were attributed to, for example, mismodelling of satellites orbits, antenna phase centre variations, troposphere, Earth Orientation Parameters, mass loading effects and monument instabilities. [less ▲]

Detailed reference viewed: 18 (2 UL)
See detailTheoretical Study of the Raman G Peak Intensity of Graphene
Reichardt, Sven UL; Wirtz, Ludger UL

Poster (2016, February 18)

Detailed reference viewed: 59 (6 UL)
Full Text
See detailA First Evaluation of the new GNSS Station Installations at the Tide Gauges of Walvis Bay and Lüderitz in the Republic of Namibia
Teferle, Felix Norman UL; Combrinck, Ludwig; Botha, Roelf et al

Poster (2016, February 11)

During September 2015 the Hartebeesthoek Radio Astronomy Observatory in collaboration with the University of Luxembourg installed two state-of-the-art continuous GNSS stations adjacent to the tide gauges ... [more ▼]

During September 2015 the Hartebeesthoek Radio Astronomy Observatory in collaboration with the University of Luxembourg installed two state-of-the-art continuous GNSS stations adjacent to the tide gauges of Walvis Bay and Lüderitz in the Republic of Namibia. These installations are the culmination of a four-year effort to get the stations established and the help of the Namibian Port Authority in this endeavour is much appreciated. The tide gauge at Walvis Bay (Global Sea Level Observing System (GLOSS) number 314) has a record in the Permanent Service for Mean Sea Level (PSMSL) Revised Local Reference (RLR) database (number 914) dating back to 1958 (data completeness 54%). The tide gauge at Lüderitz is not a GLOSS station but also has a PSMSL RLR record (number 911) since 1958 (data completeness 67%). Both tide gauges currently use a radar measurement unit and are operated by the Hydrographic Office of the South African Navy. They are the only sea level observations along a more than 3000 km stretch of the West African coast from Pointe Noire in the Republic of the Congo to Port Nolloth in the Republic South Africa, hence they form an important data source for sea level studies. The two continuous GNSS stations record observations from all visible GNSS satellites (GPS, GLONASS, BDS and Galileo) with a 1 second recording interval. The current installations support hourly data downloads, which are sufficient for most activities within the IGS, while the data have great potential to contribute not only to the TIGA working group but also to MGEX. In this study we present the first evaluation of the quality of the GNSS observations from the two new continuous GNSS stations for the first three months of operation. In the future we plan to make the data available to the scientific community. [less ▲]

Detailed reference viewed: 105 (25 UL)
Full Text
See detailTotal Impact of Periodic Terms and Coloured Noise on Velocity Estimates
Klos, Anna; Olivares, German; Teferle, Felix Norman UL et al

Poster (2016, February 05)

The uncertainties of velocity estimates for position time series of Global Navigation Satellite System (GNSS) stations are mainly affected by a misfit of the deterministic model applied to this data ... [more ▼]

The uncertainties of velocity estimates for position time series of Global Navigation Satellite System (GNSS) stations are mainly affected by a misfit of the deterministic model applied to this data. Insufficiently modelled seasonal signals will propagate into the stochastic model and falsify the results of the noise analysis besides the velocity estimates and their uncertainties. In this presentation we derived the General Dilution of Precision (GDP) of velocity uncertainties. We define this dilution as the ratio between the uncertainties of velocities determined when different deterministic and stochastic models are applied. In this way we discuss, referring to previously published results, how insufficiently modelled seasonal signals influence station velocity uncertainties with white and coloured noise. Using simulated and real data from selected (115) IGS (International GNSS Service) stations we show that the noise character affects GNSS data more than seasonals for time series longer than 9 years. [less ▲]

Detailed reference viewed: 17 (0 UL)
Full Text
See detailQuality assessment of Mulit-Year BLT Tide Gauge Benchmark Monitoring (TIGA) repro2 Solution
Hunegnaw, Addisu UL; Teferle, Felix Norman UL

Poster (2016, February)

Recently the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) has completed their repro2 solutions by re-analyzeing the full history of all relevant Global ... [more ▼]

Recently the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) has completed their repro2 solutions by re-analyzeing the full history of all relevant Global Positioning System (GPS) observations from 1995 to 2015. This re-processed data set will provide high-quality estimates of vertical land movements for more than 500 stations, enabling regional and global high-precision geophysical/geodetic studies. All the TIGA Analysis Centres (TACs) have mainly processed the GPS observations recorded by GPS stations at or close to tide gauges, which are available from the TIGA data centre at the University of La Rochelle (www.sonel.org). Following the recent improvements in processing models, strategies (http://acc.igs.org/reprocess2.html), this is the first complete re-processing attempt by the TIGA WG to provide homogeneous position time series relevant to sea level changes. In this study we report on a first multi-year daily combined solution from the TIGA Combination Centre (TCC) at the University of Luxembourg (UL) with respect to the latest International Terrestrial Reference Frame (ITRF2014). Using two independent combination software packages, CATREF and GLOBK, we have computed a first daily combined solution from TAC solutions already available for TIGA WG. These combinations allow an evaluation of any effects from the combination software and of the individual TAC parameters and their influences on the combined solution with respect to the latest ITRF2014. Some results of the UL TIGA multi-year combinations in terms of geocentric sea level changes will be presented and discussed. [less ▲]

Detailed reference viewed: 64 (13 UL)
Peer Reviewed
See detailCardinal and ordinal processing in spatial neglect
Sosson, Charlotte UL; di Luca, Samuel UL; Guillaume, Mathieu UL et al

Poster (2016, January)

Patients with spatial neglect do not only have difficulties in orienting attention in physical space but also in representational space, especially with respect to the mental representation of numbers ... [more ▼]

Patients with spatial neglect do not only have difficulties in orienting attention in physical space but also in representational space, especially with respect to the mental representation of numbers. Indeed, in a study by Zorzi et al. (2012) neglect patients were particularly slow when asked to compare the number 4 to the standard number 5, suggesting difficulties to process numbers on the left side of an internal standard. This difficulty was observed in a magnitude judgement, but not in a parity task, implying a dissociation between explicit and implicit processing of numerical magnitude. The present study aimed at replicating these findings and extending them to non-numerical sequences in order to complement the data obtained on bisection tasks (Zamarian, et al., 2007). Sixteen right-sided brain damaged patients with neglect (N+ =6; 4 females; all right handers; mean age: 55 +/- 8,7) and without neglect (N- =10; 2 females; all right hander; mean age: 48 +/- 6.2) participated in the study. They were administered the following tasks: a magnitude and a parity judgement task; an ordinal judgement task on numbers and on letters and a consonant/vowel classification task. For each task and each patient, a linear regression was computed in which the difference between the response times for the left effector (index finger) and the right effector (middle finger) was predicted by number magnitude. A negative slope will indicate the presence of a SNARC-like effect. We compared the negative slopes of the two patient groups using a Chi-square. Considering the proportion of SNARC-like effects, it appeared that, on one hand, N+ patients showed fewer SNARC-like effects than N- patients during magnitude judgements on numbers. Thus confirming the findings by Zorzi et al. (2012). On the other hand, N+ patients behaved similarly to N- patients for the parity judgements on numbers and for the order judgements both on numbers and letters. This last result suggest a dissociation between the spatial representation of magnitude and of order in N+ patients. These results point towards a specific impairment in explicit access to number magnitude in spatial hemineglect. [less ▲]

Detailed reference viewed: 39 (9 UL)
Peer Reviewed
See detailComplex problem solving and intelligence. A meta-analysis
Stadler, Matthias; Becker, N.; Gödker, M. et al

Poster (2016)

Detailed reference viewed: 7 (0 UL)
Full Text
See detailDiscrete mechanical models and upscaling techniques for discrete materials
Beex, Lars UL; Bordas, Stéphane UL

Poster (2016)

Numerous natural and man-made materials are essentially discrete structures at the mesoscale or microscale (see Fig. 1). Discrete mechanical models can be formulated to capture typical mechanical ... [more ▼]

Numerous natural and man-made materials are essentially discrete structures at the mesoscale or microscale (see Fig. 1). Discrete mechanical models can be formulated to capture typical mechanical phenomena arising from this discreteness. Failure in these materials, which often starts with the fracture of an individual bond, can be predicted based on the small-scale mechanics with these models. For failure, but also for non-local mechanics, no phenomenological descriptions are required in these models. This makes them more predictive than constitutive material models for this type of materials. [less ▲]

Detailed reference viewed: 53 (2 UL)
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Peer Reviewed
See detailSome Properties of Homogenous Trellis-Constrained Codes
Franck, Christian UL; Sorger, Ulrich UL

Poster (2016)

We consider Homogenous Trellis-Constrained Codes (HTCC), a generalization of Turbo-codes where all bits are constrained. No efficient decoding algorithm is known for these codes, so our results are ... [more ▼]

We consider Homogenous Trellis-Constrained Codes (HTCC), a generalization of Turbo-codes where all bits are constrained. No efficient decoding algorithm is known for these codes, so our results are primarily of theoretical interest. We propose a technique to derive an upper bound for the maximum-likelihood (ML) decoding of BSC errors. Our tech- nique is based on the weight distributions of the constituent codes and it can also be used when a specific number of errors e is known. We observe that with an ML-decoder some HTCC codes exhibit an error correcting performance close to that of random codes. For those codes we also observe a significant performance gap between ML-decoding and practical decoding based on belief-propagation. [less ▲]

Detailed reference viewed: 14 (5 UL)
Full Text
Peer Reviewed
See detailDetecting Electricity Theft
Glauner, Patrick UL

Poster (2016)

Detailed reference viewed: 48 (9 UL)
Full Text
Peer Reviewed
See detailPoster: PREXT: Privacy Extension for Veins VANET Simulator
Emara, Karim Ahmed Awad El-Sayed UL

Poster (2016)

Preserving location privacy is an important aspect in vehicular ad-hoc networks. Although location privacy is thoroughly studied in the past decade, it is usually skipped in VANET simulators. In this ... [more ▼]

Preserving location privacy is an important aspect in vehicular ad-hoc networks. Although location privacy is thoroughly studied in the past decade, it is usually skipped in VANET simulators. In this paper, we propose a location privacy extension, PREXT, for Veins framework. Currently, PREXT supports seven privacy schemes of different approaches including silent period, context-based and cryptographic mix-zone. It can be also easily extended to include more schemes. It includes adversary modules that can eavesdrop vehicle messages and track their movements. This adversary is used in measuring the gained privacy in terms of several popular metrics such as entropy, traceability and pseudonym usage statistics. We utilize this extension to compare among different schemes in an urban scenario. [less ▲]

Detailed reference viewed: 26 (3 UL)
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Peer Reviewed
See detailShort-term Time Series Forecasting with Regression Automata
Lin, Qin; Hammerschmidt, Christian UL; Pellegrino, Gaetano et al

Poster (2016)

We present regression automata (RA), which are novel type syntactic models for time series forecasting. Building on top of conventional state-merging algorithms for identifying automata, RA use numeric ... [more ▼]

We present regression automata (RA), which are novel type syntactic models for time series forecasting. Building on top of conventional state-merging algorithms for identifying automata, RA use numeric data in addition to symbolic values and make predictions based on this data in a regression fashion. We apply our model to the problem of hourly wind speed and wind power forecasting. Our results show that RA outperform other state-of-the-art approaches for predicting both wind speed and power generation. In both cases, short-term predictions are used for resource allocation and infrastructure load balancing. For those critical tasks, the ability to inspect and interpret the generative model RA provide is an additional benefit. [less ▲]

Detailed reference viewed: 10 (0 UL)
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See detailMultiscale hydrogeological and hydrogeophysical approach to monitor vadose zone hydrodynamics of a karst system
Watlet, Arnaud; Poulain, Amaël; Francis, Olivier UL et al

Poster (2016)

The vadose zone of karst systems plays an important role on the water dynamics. In particular, temporary perched aquifers can appear in the subsurface due to changes of weather conditions, reduced ... [more ▼]

The vadose zone of karst systems plays an important role on the water dynamics. In particular, temporary perched aquifers can appear in the subsurface due to changes of weather conditions, reduced evapotranspiration and the vertical gradients of porosity and permeability. Although many difficulties are usually encountered when studying karst environments due to their heterogeneities, cave systems offer an outstanding opportunity to investigate vadose zone from the inside. We present a multi-scale study covering two years of hydrogeological and geophysical monitoring of the Lomme Karst System (LKS) located in the Variscan fold-and-thrust belt (Belgium), a region (∼3000 ha) that shows many karstic networks within Devonian limestone units. Hydrogeological data cover the whole LKS and involve e.g. flows and levels monitoring or tracer tests performed in both vadose and saturated zones. Such data bring valuable information on the hydrological context of the studied area at the catchment scale. Combining those results with geophysical measurements allows validating and imaging them at a smaller scale, with more integrative techniques. Hydrogeophysical measurements are focused on only one cave system of the LKS, at the Rochefort site (∼40 ha), taking benefit of the Rochefort Cave Laboratory (RCL) infrastructures. In this study, a microgravimetric monitoring and an Electrical Resistivity Tomography (ERT) monitoring are involved. The microgravimetric monitoring consists in a superconducting gravimeter continuously measuring gravity changes at the surface of the RCL and an additional relative gravimeter installed in the underlying cave located 35 meters below the surface. While gravimeters are sensible to changes that occur in both the vadose zone and the saturated zone of the whole cave system, combining their recorded signals allows enhancing vadose zone’s gravity changes. Finally, the surface ERT monitoring provide valuable information at the (sub)-meter scale on the hydrological processes that occur in the vadose zone. Seasonal water variations and preferential flow path are observed. This helps separating the hydrological signature of the vadose zone from that of the saturated zone. [less ▲]

Detailed reference viewed: 41 (7 UL)
Full Text
See detailAssessment of BLT Tide Gauge Benchmark Monitoring (TIGA) repro2 Solutions
Hunegnaw, Addisu UL; Teferle, Felix Norman UL

Poster (2015, December 17)

In 2013 the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) started their reprocessing campaign, which proposes to re-analyze all relevant Global Positioning ... [more ▼]

In 2013 the International GNSS Service (IGS) Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) started their reprocessing campaign, which proposes to re-analyze all relevant Global Positioning System (GPS) observations from 1994 to 2013. This re-processed dataset will provide high quality estimates of land motions, enabling regional and global high-precision geophysical/geodetic studies. Several of the individual TIGA Analysis Centres (TACs) have completed processing the full history of GPS observations recorded by the IGS global network, as well as, many other GPS stations at or close to tide gauges, which are available from the TIGA data centre at the University of La Rochelle (www.sonel.org). Following the recent improvements in processing models and strategies, this is the first complete reprocessing attempt by the BLT TIGA Analysis centre to provide homogeneous position time series. We report the quality of the multi-year daily solutions from the consortium of the British Isles continuous GNSS Facility (BIGF) and the University of Luxembourg TIGA Analysis Centres (BLT) based on the Bernese GNSS Software Version 5.2 using a double difference (DD) network processing strategy. [less ▲]

Detailed reference viewed: 39 (8 UL)
Peer Reviewed
See detailMetacognitive approach of decision processes implied in time perception
Lamotte, Mathilde UL; Droit-Volet, Sylvie; Izaute, Marie

Poster (2015, November)

Detailed reference viewed: 11 (0 UL)
Full Text
See detailSignal Obstructions at GNSS Stations: Benefits From Multi-GNSS Observations
Abraha, Kibrom Ebuy UL; Teferle, Felix Norman UL; Hunegnaw, Addisu UL et al

Poster (2015, October 27)

The current accuracy of IGS products, few centimeter level, requires amongst other things that the location for GNSS antennas are nearly optimal for GNSS observations. This includes a low multipath ... [more ▼]

The current accuracy of IGS products, few centimeter level, requires amongst other things that the location for GNSS antennas are nearly optimal for GNSS observations. This includes a low multipath environment and little to no signal obstructions. However, this is not guaranteed for every station especially in urban areas and mountainous regions. As some applications such as GNSS for sea level studies or to monitor landslides require GNSS antennas to be installed at a specific site, it is clear that the environment might not be favourable for GNSS observations. In this study, we investigate the effect of signal obstructions on station positions, specifically the height component, based on simulated obstruction scenarios using a modified Bernese GNSS Software version 5.2 (BSW52). The behaviours of different obstruction scenarios and the impact of multi-GNSS (GPS+GLONASS for now) observations for both clear and obstructed stations are discussed. [less ▲]

Detailed reference viewed: 97 (18 UL)
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See detailPraxis- a Kontaktdag
Böwen, Petra UL; Dujardin, Céline UL; Romberg, Kathrin UL

Poster (2015, October 22)

Wir bieten Studierenden und Arbeitgebern die Möglichkeit, persönlichen Kontakt herzustellen und/oder zu pflegen. Auch Studieninteressierte und die interessierte Öffentlichkeit können „Wissenschaft und ... [more ▼]

Wir bieten Studierenden und Arbeitgebern die Möglichkeit, persönlichen Kontakt herzustellen und/oder zu pflegen. Auch Studieninteressierte und die interessierte Öffentlichkeit können „Wissenschaft und Praxis“ hautnah erleben. Im Mittelpunkt steht der persönliche Kontakt. Sie als Praxiseinrichtungen bekommen die Möglichkeit, sich und Ihre Arbeit zu präsentieren. Sie können Kontakte mit potentiellen Praktikanten, Honorarkräften und evtl. zukünftigen Berufseinsteigern herstellen und auch ehrenamtliche Mitarbeiter gewinnen. Sie als Studierende können Kontakte knüpfen für ein konkretes Praktikum, zum Kennenlernen eines bestimmten Praxisfeldes oder zur Kontaktaufnahme mit einem potentiellen Arbeitgeber. [less ▲]

Detailed reference viewed: 42 (4 UL)
See detailQuantum moment maps and retracts for symmetric bounded domains
Korvers, Stéphane UL

Poster (2015, October)

Detailed reference viewed: 15 (1 UL)
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Peer Reviewed
See detailIdentification with Europe – a matter of exposure?
Murdock, Elke UL; Ferring, Dieter UL

Poster (2015, September 11)

Research on European identity has consistently found low identification with the supra-national category European for participants with low experience levels of Europe. In some instances, higher ... [more ▼]

Research on European identity has consistently found low identification with the supra-national category European for participants with low experience levels of Europe. In some instances, higher experience levels of Europe, for example through language competence, exchange programs or work experience have also produced higher levels of identification with Europe. However, overall identification levels with Europe rest still low. To assess the impact of exposure to Europe on identification with Europe, two empirical studies were carried out among adolescents who are growing up with high experience levels of Europe. Participants are students at the European School of Luxembourg, which is divided into language sections representing the member states of the European Union. The students learn a second language from Primary school onwards and more languages are added later on. They attend weekly “European hour” classes and many parents work for one of the European institutions located in Luxembourg. Luxembourg itself is a trilingual country, sharing borders with three countries and a foreign population of 44%. In the first study, 106 students, average age M = 13.64, SD = 1.72 participated and the salience of the supra-national category European was assessed in the spontaneous self-concept using a modified version of the Twenty Statement Test. None of the European school students mentioned “European” in their spontaneous self-concept. In the second study (N = 204, average age M =15.16, SD = 0.84) students were asked to self-categorize in terms of nationality. Bicultural self-definitions were common, but only one student described herself as “European”. These findings amongst the high exposure group to Europe are discussed against a background of identity theories including theories on national identity and wider collective identities. I will argue that European identity is likely to remain elusive and alternative research approaches are suggested within a globalizing world. [less ▲]

Detailed reference viewed: 21 (2 UL)
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Peer Reviewed
See detailZur Relevanz psychosozialer Arbeitsbedingungen und mentaler Arbeitsanforderungen für das Erleben von Stress und Burnout.
Sischka, Philipp UL; Steffgen, Georges UL

Poster (2015, September 07)

Das Job Demands-Resources-Modell(JD-R-Modell, z.B.Bakker & Demerouti, 2007; Schaufeli, Bakker, vanRhenen, 2009) weist auf die Bedeutung von psycho-sozialen Arbeitsbedingungen für das Erleben von Stress ... [more ▼]

Das Job Demands-Resources-Modell(JD-R-Modell, z.B.Bakker & Demerouti, 2007; Schaufeli, Bakker, vanRhenen, 2009) weist auf die Bedeutung von psycho-sozialen Arbeitsbedingungen für das Erleben von Stress und Burnout hin. Während unterschiedliche ‚JobDemands‘ (Berufsbelastungen, z.B. emotionale, kognitive, physische) einen negativen Einfluss auf die Gesundheit ausüben können, können sich ‚JobResources‘ positiv auf die Gesundheit auswirken. Diese Ressourcen können unterschiedliche Formen annehmen, z.B. soziale Unterstützung durch Kollegen oder eine hohe Autonomie bei der Arbeit. In dieser Studie wurde geprüft, ob wahrgenommener Respekt, Kooperation mit Arbeitskollegen sowie Autonomie bei der Ausführung der Arbeit als Job Ressourcen einen Einfluss auf das Erleben von Stress und Burnout haben. [less ▲]

Detailed reference viewed: 95 (12 UL)
See detailGroundwater Storage in a Karst Vadose Zone Evidenced Using Gravimetric and Surface-to-borehole ERT Monitoring Systems
Watlet, A.; Kaufmann, O.; Francis, Olivier UL et al

Poster (2015, September 06)

Detailed reference viewed: 54 (8 UL)
See detailProblematizing science as a primary school discipline: Learning from contingencies and diversities
Schreiber, Catherina UL; Siry, Christina UL; Reuter, Bob UL et al

Poster (2015, September 03)

This paper puts the idea of a contingent nature of science at its fore, asking what we as researchers can learn from seemingly irreconcilable differences in our approaches and interpretations to past ... [more ▼]

This paper puts the idea of a contingent nature of science at its fore, asking what we as researchers can learn from seemingly irreconcilable differences in our approaches and interpretations to past, present and future developments in science education. To do so, we aim to explore the potentials of multi-perspectivity in an academic self-experiment. The idea is to problematize science as a school discipline from different theoretical, disciplinary and methodological standpoints. By taking one concrete example of a Luxembourgian primary school curriculum document, four researchers will independently apply their individual lenses on science as a school discipline. Concretely, the coverage of the hedgehog as a “characteristic animal” in our primary school curriculum will be commented on in historical, sociocultural and pedagogical perspectives. This concrete curricular example is seemingly defined and non disputable as a content theme in primary school science education in Luxembourg, and is also to be found in international curriculum policy documents. Yet a seemingly proven fact can be interpreted in multiple ways, not only to bridge controversies, as it is done so often, but as exploring the differences in a self-reflective manner. Through such multiple interpretations, we are specifically looking for inconsistencies between the four different narratives, instead of focusing on consensual conclusions or firm and consistent patterns. Instead we will follow a multi-layered approach to research in order to undertake a métissage approach to analyzing a component of the science pedagogical practice, allowing the different understandings on the Luxembourgian science curriculum to remain and complement each other in a complex manner. [less ▲]

Detailed reference viewed: 136 (36 UL)
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See detailRelationship between cardiovascular reactivity and the perception of the thermal grill illusion of pain
Scheuren, Raymonde UL; Duschek, Stefan; Schulz, André UL et al

Poster (2015, September 03)

Alterations in blood pressure (BP) and concomitant changes in baroreceptor activation contribute to the modulation of pain sensitivity to warrant homeostatic regulation processes [1][2]. Numerous pain ... [more ▼]

Alterations in blood pressure (BP) and concomitant changes in baroreceptor activation contribute to the modulation of pain sensitivity to warrant homeostatic regulation processes [1][2]. Numerous pain studies have described an inverse relationship between BP and nociceptive sensitivity [3][4][5]. It is not known whether a similar relationship plays a role in the framework of the induction of pain in the absence of noxious stimulation. The thermal grill (TG) paradigm is commonly used to trigger this type of paradoxical pain also termed thermal grill illusion of pain (TGI). The goal of the present study was to explore the relationship between cardiovascular activity/reactivity and paradoxical pain sensitivity to get additional insight in the variability of responsiveness (responders and non-responders) to TG stimulation described in the literature [6][7]. We hypothesized that higher BP would be associated with stronger pain inhibitory effects in participants not perceiving the thermal grill illusion of pain (TGI). We moreover expected that the perception of paradoxical pain in the responder group would be paired with lower BP. We tested this hypothesis by comparing both groups with respect to their spontaneous cardiovascular activity (recorded in resting conditions) and their cardiovascular responses to TG stimulation. [less ▲]

Detailed reference viewed: 56 (3 UL)
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See detailCognitive Processing of Interoceptive Information and Negative Health Outcomes
Sütterlin, Stefan; Scheuren, Raymonde UL; Mueller, Sven et al

Poster (2015, September 02)

Detailed reference viewed: 19 (2 UL)
Peer Reviewed
See detailMagnetic SANS correlation functions of bulk magnetic materials
Mettus, Denis UL; Michels, Andreas UL

Poster (2015, September 02)

We present model calculations, based on the continuum theory of micromagnetics, for the correlation function of the spin-misalignment SANS cross section of bulk ferromagnets (e.g. elemental ... [more ▼]

We present model calculations, based on the continuum theory of micromagnetics, for the correlation function of the spin-misalignment SANS cross section of bulk ferromagnets (e.g. elemental polycrystalline ferromagnets, soft and hard magnetic nanocomposites, nanoporous ferromagnets, or magnetic steels). For such materials, the spin disorder which is related to spatial variations in the saturation magnetization and magnetic anisotropy field results in strong spin-misalignment scattering dΣM/dΩ along the forward direction [1]. When the applied magnetic field is perpendicular to the incoming neutron beam, the characteristics of dΣM/dΩ (e.g. the angular anisotropy on a two-dimensional detector or the asymptotic power-law exponent) are determined by the ratio of magnetic anisotropy-field strength Hp to the jump ΔM in the saturation magnetization at internal interfaces. Here, we analyze the corresponding one and two-dimensional real-space correlations as a function of applied magnetic field, ratio Hp/ΔM, single-particle form factor, and particle volume fraction. Finally, we compare the theoretical results for the correlation function to experimental data on a Nd-Fe-B-based nanocomposite. [less ▲]

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Peer Reviewed
See detailDoes body motion influence arithmetic problem solving
Sosson, Charlotte UL; Guillaume, Mathieu UL; Schuller, Anne-Marie UL et al

Poster (2015, September)

Recent evidence indicates that body movements can influence number processing (Hartmann, et al., 2012) and arithmetic problem solving (Lugli, et al., 2013). Thus it was for instance observed that moving ... [more ▼]

Recent evidence indicates that body movements can influence number processing (Hartmann, et al., 2012) and arithmetic problem solving (Lugli, et al., 2013). Thus it was for instance observed that moving the arm rightward and upward led to better performance during additions and leftward and downward during subtractions (Wiemers, et al., 2014). These results could be explained by the fact that left/right body motion can be (in)compatible with the attentional motion towards the left/right on the mental number line known to underlie subtractions/additions (i.e. operational momentum effect) (McCrink, et al., 2007; Lindemann, et al., 2011). The compatible situations (i.e. leftwards motion - subtraction and rightwards motion - addition) thus are expected to facilitate arithmetic performance compared to incompatible ones. The present study was designed to test this hypothesis during arithmetic problem solving using: (1) physical passive rotary whole-body motion and (2) virtual environment mimicking a similar passive body motion. Findings of the present study confirm the classical effects known to play a role in arithmetic problem solving. They also revealed that passive rotary whole-body motion - implemented physically or by virtual reality - had no particular effect on the solving of calculations. This is in contrast with previous studies that showed an influence of active head/arm or passive translational movements on numerical task performance. [less ▲]

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Peer Reviewed
See detailTop-down control over pain in fibromyalgia patients: An experimental study.
Van Ryckeghem, Dimitri; Rost, Silke UL; Van Damme, Stefaan et al

Poster (2015, September)

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Peer Reviewed
See detailMagnetic small-angle neutron scattering: beyond the particle-matrix concept
Michels, Andreas UL

Poster (2015, September)

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Full Text
See detailA global description of the fine Simpson moduli space of 1-dimensional sheaves supported on plane quartics
Iena, Oleksandr UL

Poster (2015, September)

We give a global description of the fine Simpson moduli spaces of 1-dimensional sheaves supported on plane quartics.

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Peer Reviewed
See detailActivity tracking and indoor positioning with a wearable magnet
Popleteev, Andrei UL

Poster (2015, September)

This paper presents an unconventional application of digital compass sensors for localization and activity monitoring in ambient assisted living scenarios. Benefits and limitations of the proposed ... [more ▼]

This paper presents an unconventional application of digital compass sensors for localization and activity monitoring in ambient assisted living scenarios. Benefits and limitations of the proposed approach are reviewed and compared to these of traditional tracking methods, such as wearable devices, surveillance cameras and device-free localization. [less ▲]

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See detailParafermion bound states and the fractional Josephson effect in Rashba spin-orbit coupled nanowires
Pedder, Christopher UL; Meng, Tobias; Tiwari, Rakesh et al

Poster (2015, September)

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See detailElectronic and Vibrational proprieties of graphene on Ir(111) and SiC(100)
Pereira Coutada Miranda, Henrique UL; Molina-Sanchez, Alejandro UL; Wirtz, Ludger UL

Poster (2015, September)

In the last years, graphene has become one of the most studied materials due to its peculiar electronic, optical, thermal, and mechanical properties. It is thus of major importance, for practical ... [more ▼]

In the last years, graphene has become one of the most studied materials due to its peculiar electronic, optical, thermal, and mechanical properties. It is thus of major importance, for practical applications, to study how the electronic and vibrational proprieties of graphene change when deposited on a substrate. The non-commensurability of the unit cell of graphene with the substrate leads to the formation of Moiré patterns with accordingly large supercell sizes. Ab-initio calculations using standard plane-wave based codes on these large systems are of high computational cost even for the ground-state calculations. We show the effect that such Moiré patterns have on the band structure by projecting the resulting electronic structure and phonon dispersion onto the unit cell of free-standing graphene with an unfolding scheme. We compare our results with HREELS measurements of the phonon dispersion of graphene on Ir(111). The accurate knowledge of the interaction graphene-substrate will provide important information for future applications of graphene on electronic devices. Work performed in collaboration with the experimental groups of J. Kroeger (TU Ilmenau, Germany) and T. Seyller (TU Chemnitz, Germany). [less ▲]

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See detailFracture in augmented reality
Bilger, Alexandre UL; Cotin, Stephane; Dequidt, Jeremie et al

Poster (2015, August)

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See detailRaman spectroscopy as probe of nanometre-scale strain variations in graphene
Neumann, Christoph; Reichardt, Sven UL; Venezuela, Pedro et al

Poster (2015, July 14)

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See detailDevelopment and validation of a test intrument to assess basic motor qualifications in primary school
Scheuer, Claude; Bund, Andreas UL; Herrmann, Christian

Poster (2015, July)

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See detailFEniCS in Linux Containers
Hale, Jack UL; Li, Lizao; Wells, Garth N.

Poster (2015, June 29)

We present a collection of Docker images for running FEniCS in Linux containers. With one command, a user can launch a lightweight container that provides a consistent environment for using or developing ... [more ▼]

We present a collection of Docker images for running FEniCS in Linux containers. With one command, a user can launch a lightweight container that provides a consistent environment for using or developing FEniCS. Once the initial image has been fetched, 'FEniCS terminals' can be launched near-instantly. We show through a range of tests that performance within a container is to equal to that on the host system. Moreover, MPI programs can be run from inside the container, and host CPU vectorisation features can be exploited. In practice, container versions of FEniCS will be faster than user installations as the container images can be carefully tuned for performance. Live demonstrations of user and developer container use will be presented. The containers are built and hosted on Docker Hub [less ▲]

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See detailCalibration of the Tide Gauge at King Edward Point, South Georgia Island, South Atlantic Ocean
Teferle, Felix Norman UL; Hunegnaw, Addisu UL; Woodworth, P. L. et al

Poster (2015, June 27)

In 2008 a new pressure tide gauge with Global Sea Level Observing System Number 187 was installed at King Edward Point (KEP), South Georgia Island, South Atlantic Ocean. This installation was carried out ... [more ▼]

In 2008 a new pressure tide gauge with Global Sea Level Observing System Number 187 was installed at King Edward Point (KEP), South Georgia Island, South Atlantic Ocean. This installation was carried out as part of the Antarctic Circumpolar Current Levels by Altimetry and Island Measurements (ACCLAIM) programme. In 2013 the KEP Geodetic Observatory was established in support of various scientific applications including the monitoring of vertical land movements at KEP. Currently, the observatory consists of two state-of-the-art Global Navigation Satellite System (GNSS) stations with local benchmark networks. This ties all benchmarks and the tide gauge into the International Terrestrial Reference Frame 2008, and allows the establishment of a local height datum in a global height system through the use of a global gravitational model. In 2014 a tide board was added to the tide gauge, which, together with the GNSS and levelling observations, now enables a calibration of the tide gauge. This will make it possible to include the KEP tide gauge in the Permanent Service for Mean Sea Level (PSMSL) database. In this study, we will present the results from the calibration of the tide gauge using the GNSS observations from the KEP Geodetic Observatory for the period from February 2013 to present, the levelling campaigns in 2013 and 2014, and geoid undulations derived from a seamless combination of the latest Gravity Observation Combination (GOCO) 05S and Earth Gravitational Model (EGM) 2008 models. [less ▲]

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See detailImpact of Limited Multi-GNSS Visibility on Vertical Land Movement Estimates
Abraha, Kibrom Ebuy UL; Teferle, Felix Norman UL; Hunegnaw, Addisu UL et al

Poster (2015, June 27)

The number of GNSS satellites and their geometry directly affect the quality of positioning and derived satellite products. Accordingly, the International GNSS Service (IGS) recommends GNSS antennas to be ... [more ▼]

The number of GNSS satellites and their geometry directly affect the quality of positioning and derived satellite products. Accordingly, the International GNSS Service (IGS) recommends GNSS antennas to be installed away from natural and man-made surfaces and structures, which may affect the incoming signals through severe multipath or obstructions. Following these recommendations, continuous GNSS (cGNSS) stations are generally located in low multipath environments with minimal signal obstructions. However, some applications require GNSS antennas to be installed at specific locations in order to measure local processes. Hence, in support of sea level studies, cGNSS stations must be installed close to or at tide gauges in order to accurately monitor the local vertical land movements experienced by the sea level sensors. However, the environment at the tide gauge might not be optimal for GNSS observations due to the aforementioned station-specific effects, which degrade the quality of coordinate solutions.This first study investigates the impact of severe signal obstructions on long-term monitoring results by use of simulated and real observations for selected cGNSS stations, and evaluates if the use of multi-GNSS (GPS+GLONASS) constellations will benefit derived results. To investigate these effects, we implemented azimuth and elevation dependent masking in the Bernese GNSS Software version 5.2. We present our preliminary results on the impact of different obstruction scenarios and combined GPS and GLONASS solutions on coordinate and vertical land movement estimates. [less ▲]

Detailed reference viewed: 141 (41 UL)