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See detailInverse simulation for retrieving the undeformed position for hyperelastic materials : application to breast simulations
Mazier, Arnaud UL; Bilger, Alexandre; Forte, Antonio et al

Scientific Conference (2020, July)

Detailed reference viewed: 57 (18 UL)
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See detailThe development and validation of a short conscientiousness questionnaire for large-scale educational assessment
van der Westhuizen, Lindie UL; Franzen, Patrick UL; Arens, A. Katrin et al

Scientific Conference (2020, July)

Conscientiousness and its subfacets are related to multiple learning-related outcomes. MacCann, Duckworth and Roberts (2009) developed a questionnaire measuring seven subfacets of conscientiousness with ... [more ▼]

Conscientiousness and its subfacets are related to multiple learning-related outcomes. MacCann, Duckworth and Roberts (2009) developed a questionnaire measuring seven subfacets of conscientiousness with 59 items. However, the resources required to complete such long scales often renders it unsuitable for large-scale educational assessment. Consequently, an economic and psychometrically sound conscientiousness questionnaire that is specifically customized for this context is needed. We developed and validated a short version of the MacCann et al. (2009) questionnaire. In study 1, French and German adaptations of the questionnaire were administered to a representative dataset comprising all ninth-graders in Luxembourg (N1=6325, Cohort 2017). Using an exhaustive search algorithm, we identified the optimal combination of four items for each subfacet by simultaneously considering three criteria: goodness of fit, factor saturation, and scalar measurement invariance across the German and French versions. In study 2, we validated our short 28-item questionnaire on a second, independent sample comprising 6,279 Luxembourgish ninth-graders (Cohort 2018). A 7-factor model assuming separate factors for each subfacet obtained acceptable fit (CFI=.93, RMSEA=.04, SRMR=.06). The criterion validity for each subfacet was tested by examining the relation to standardized achievement tests (SATs). In study 3, drawing on a dataset of 275 tenth-graders (linked longitudinally with the ninth-grade data from study 1), evidence of predictive validity (i.e., school grades) was examined. The subfacets of industriousness, caution and perfectionism showed the strongest relations with both SATs (study 2) and school grades (study 3). Our study delivered a short, valid and reliable questionnaire for the assessment of seven conscientiousness facets in the educational context. The scale is invariant across the German and French language versions and its brevity makes it suitable for large-scale educational assessment. [less ▲]

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See detailPractical aspects of the Bank-Weiser estimator implementation and Biomechanics applications.
Bulle, Raphaël UL; Bordas, Stéphane UL; Chouly, Franz et al

Scientific Conference (2020, July)

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See detailAutomated Repair of Feature Interaction Failures in Automated Driving Systems
Ben Abdessalem, Raja; Panichella, Annibale; Nejati, Shiva UL et al

in Proceedings of the 29th ACM SIGSOFT International Symposium on Software Testing and Analysis (ISSTA 2020) (2020, July)

In the past years, several automated repair strategies have been proposed to fix bugs in individual software programs without any human intervention. There has been, however, little work on how automated ... [more ▼]

In the past years, several automated repair strategies have been proposed to fix bugs in individual software programs without any human intervention. There has been, however, little work on how automated repair techniques can resolve failures that arise at the system-level and are caused by undesired interactions among different system components or functions. Feature interaction failures are common in complex systems such as autonomous cars that are typically built as a composition of independent features (i.e., units of functionality). In this paper, we propose a repair technique to automatically resolve undesired feature interaction failures in automated driving systems (ADS) that lead to the violation of system safety requirements. Our repair strategy achieves its goal by (1) localizing faults spanning several lines of code, (2) simultaneously resolving multiple interaction failures caused by independent faults, (3) scaling repair strategies from the unit-level to the system-level, and (4) resolving failures based on their order of severity. We have evaluated our approach using two industrial ADS containing four features. Our results show that our repair strategy resolves the undesired interaction failures in these two systems in less than 16h and outperforms existing automated repair techniques. [less ▲]

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See detailSystematic derivation of Generalized Langevin Equations for coarse-graining and bridge-scaling procedures
Meyer, Hugues UL

Scientific Conference (2020, July)

In many branches of physics, one must often deal with processes involving a huge number of degrees of freedom. Instead of describing the dynamics of each individual of them, one rather wants to ... [more ▼]

In many branches of physics, one must often deal with processes involving a huge number of degrees of freedom. Instead of describing the dynamics of each individual of them, one rather wants to characterize the process of interest via a small set of observ- ables that capture its main features of the process. Even if the microscopic dynamics can be resolved using Newton’s equations of motion, it quickly becomes a computation- ally very expensive calculation to make. It is however much more convenient to come up with a self-consistent equation of motion for the ’global’ observable of interest itself in order to reduce the complexity of the problem. The development of the Mori-Zwanzig formalism in the 1960’s allowed to systematically derive such equations for arbitrary observables in stationary processes. This framework, derived from first principles by means of projection operator techniques, proves the structure of what is now known as the Generalized Langevin Equation, i.e. a stochastic equation of motion which a priori exhibits memory effects in the form on non-localities in time. We propose to extend the formalism and its corollaries to a broad class of out-of- equilibrium processes. We show that the structure of the Generalized Langevin Equa- tion is overall robust but must be adapted to account for the non-stationary dynamics [1,2]. The function that controls memory effects the stochastic term are related through a relation that can be associated to fluctuation-dissipation theorems. This formalism is very convenient to study two-time auto-correlation functions for which we can write a self-consistent differential equation as well. We finally show a new method to evaluate the memory function from numerical or experimental data [3]. [less ▲]

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See detailImmersive Telepresence Framework for Remote Educational Scenarios
Botev, Jean UL; Rodríguez Lera, Francisco J.

in Proceedings of the 22nd International Conference on Human-Computer Interaction (HCI International) (2020, July)

Detailed reference viewed: 69 (10 UL)
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See detailDeveloping an Interactive Tabletop Mediated Activity to Induce Collaboration by Implementing Design Considerations Based on Cooperative Learning Principles
Sunnen, Patrick UL; Arend, Béatrice UL; Heuser, Svenja UL et al

in Stephanidis, Constantine; Antona, Margherita (Eds.) HCI International 2020 - Posters (2020, July)

Constructive collaboration can be a difficult matter. For this reason, we are implementing and studying an interactive-tabletop-mediated activity that aims at inducing collaboration among participants ... [more ▼]

Constructive collaboration can be a difficult matter. For this reason, we are implementing and studying an interactive-tabletop-mediated activity that aims at inducing collaboration among participants. The resulting activity ‘Orbitia’ is designed as a serious game. Participants are asked to act as a space- mining crew, which has to collect minerals with a rover and rely on a camera- drone for reconnaissance, while keeping the rover out of harm and managing limited resources. In this paper we provide an account of how we designed Orbitia’s pedagogical structuring by relying on the Johnsons’ cooperative learning approach whose fundamental concept is “positive interdependence”. More particularly, we show how we worked on resource, role and task inter- dependence to design three collaboration-inducing ‘flagship’ devices: the rover- steering-device (RSD), the item-locating-device (ILD) and the responsibility- activating-device (RAD). [less ▲]

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See detail'Being a space mining crew': How participants jointly discover their complementary resources while engaging into a serious game at an interactive tabletop
Arend, Béatrice UL; Sunnen, Patrick UL; Heuser, Svenja UL et al

in L.Gomez Chova, A. Lopez Martinez, I. Candel Torres: Proceedings, International Conference on Education and New Learning Technologies 2020 (2020, July)

Detailed reference viewed: 113 (6 UL)
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See detailMeasuring Executive Functions and their Relations to Mathematical Skills in Preschool Children: A Meta-Analysis
Emslander, Valentin UL; Scherer, Ronny

Scientific Conference (2020, July)

Introduction: Executive functions (inhibition, attention shifting, working memory) are linked to mathematical skills in school students and adults. This link is particularly important because performance ... [more ▼]

Introduction: Executive functions (inhibition, attention shifting, working memory) are linked to mathematical skills in school students and adults. This link is particularly important because performance in school mathematics is predictive of various competencies later in life. While some researchers argue that tests of executive functions and mathematical skills measure the same underlying construct, others argue that they measure distinct but correlated constructs. Also, evidence on the differentiation of cognitive skills over time exists. Clarifying the relation between executive functions and mathematical skills is, however, challenging, especially because preschoolers cannot fill in commonly used questionnaires that require them to read. As a consequence, researchers have to resort to behavioral, verbal, apparatus-, or computer-based assessments of executive functions. Objectives/Methodology: With this meta-analysis of 26 studies containing 238 effect sizes, we examined the link between executive functions and early mathematical skills for a total sample of 24,256 preschool children. Specifically, we synthesized the corresponding correlations and sought to clarify which executive function assessments were used for preschool children and how the assessment characteristics may moderate the correlation between executive functions and mathematical skills. Results: Utilizing three-level random-effects meta-analysis, we found a moderate correlation between executive functions and mathematical skills in preschool children, r = 0.35. The type of assessment (behavioral, verbal, apparatus-, or computer-based assessments) did not moderate this relation. Differentiating between the three executive functions revealed average correlations of r = 0.31 between math and inhibition, r = 0.38 between math and attention shifting, and r = 0.36 between math and updating. These analyses will be supplemented by further moderator analyses. Conclusions: Our findings support the significant link between executive functions and mathematical skills in preschoolers—yet, the average correlations do not suggest that both measures are identical. Results will be discussed against the background of deployed assessments and testing environments. [less ▲]

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See detailImproving open data accessibility through package development and community work
Kozlowski, Diego UL; Tiscornia, Pablo; Weksler, Guido et al

Poster (2020, July)

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See detailUML Consistency Rules:a Case Study with Open-Source UML Models
Torre, Damiano UL; Labiche, Yvan; Genero, Marcela et al

in Proceedings of the 8th International Conference on Formal Methods in Software Engineering (2020, July)

UML models are standard artifacts used by software engineers for designing software. As software is designed, different UML diagram types (e.g., class diagrams and sequence diagrams) are produced by ... [more ▼]

UML models are standard artifacts used by software engineers for designing software. As software is designed, different UML diagram types (e.g., class diagrams and sequence diagrams) are produced by software designers. Since the various UML diagram types describe different aspects of a software system, they are not independent but strongly depend on each other, hence they must be consistent. Inconsistencies cause faults in the final software systems. It is, therefore, paramount that they get detected, analyzed, and fixed. Consistency rules are a useful tool proposed in the literature to detect inconsistencies. They categorize constraints that help in identifying inconsistencies when violated. This case study aims at collecting and analyzing UML models with OCL consistency rules proposed in the literature and at promoting the development of a reference benchmark that can be reused by the (FM-)research community. We collected 33 UML consistency rules and 206 different UML diagrams contained in 34 open-source UML models presented in the literature. We propose an FM-based encoding of the consistency rules in OCL. This encoding allows analyzing whether the consistency rules are satisfied or violated within the 34 UML models. To assess the proposed benchmark, we analyzed how the UML models, consistency rules, diagram types contained in the benchmark help in assessing the consistency of UML models, and the consistency of diagrams across the different software development phases. Our results show that the considered UML models and consistency rules allowed identifying 2731 inconsistencies and that those inconsistencies refer to different software development phases. We concluded that the considered UML models and consistency rules could be considered as an initial benchmark that can be further extended by the research community. [less ▲]

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See detailChallenges Towards Production-Ready Explainable Machine Learning
Veiber, Lisa UL; Allix, Kevin UL; Arslan, Yusuf UL et al

in Veiber, Lisa; Allix, Kevin; Arslan, Yusuf (Eds.) et al Proceedings of the 2020 USENIX Conference on Operational Machine Learning (OpML 20) (2020, July)

Machine Learning (ML) is increasingly prominent in or- ganizations. While those algorithms can provide near perfect accuracy, their decision-making process remains opaque. In a context of accelerating ... [more ▼]

Machine Learning (ML) is increasingly prominent in or- ganizations. While those algorithms can provide near perfect accuracy, their decision-making process remains opaque. In a context of accelerating regulation in Artificial Intelligence (AI) and deepening user awareness, explainability has become a priority notably in critical healthcare and financial environ- ments. The various frameworks developed often overlook their integration into operational applications as discovered with our industrial partner. In this paper, explainability in ML and its relevance to our industrial partner is presented. We then dis- cuss the main challenges to the integration of ex- plainability frameworks in production we have faced. Finally, we provide recommendations given those challenges. [less ▲]

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See detailConnecting the real world to mathematical models in elementary schools in Luxemburg
Haas, Ben; Kreis, Yves UL; Lavicza, Zsolt

in Proceedings of the British Society for Research into Learning Mathematics (2020, July), 40(2), 1-6

In the Luxemburgish national curriculum for elementary schools (MENFP, 2011) experimentations and discoveries of mathematics concepts in courses are strongly recommended. Elementary school teachers should ... [more ▼]

In the Luxemburgish national curriculum for elementary schools (MENFP, 2011) experimentations and discoveries of mathematics concepts in courses are strongly recommended. Elementary school teachers should engage students in active mathematical modelling approaches, where they can develop processes and content skills through discoveries. Moreover, learned skills should be connected to real-world problems and situations to foster a better understanding of students’ living environments. Nevertheless, this teaching culture in mathematics is unusual in elementary schools and teachers tend to teach based on textbooks. Students mostly learn mathematics by imitation and repetition rather than through modelling mathematics with real-world problems and situations. Thus, to develop new methodologies in teaching mathematics and to meet the requirements of the national curriculum, we designed different technology-enhanced teaching and learning methods to engage students in experimental approaches within and outside classrooms. Moreover, we conducted three studies with digital and physical modelling, augmented reality, and a tutoring system in elementary school mathematics courses. Based on our collected data, we identified settings and tasks likely to support active mathematical modelling approaches. [less ▲]

Detailed reference viewed: 58 (3 UL)
See detailWhen historians create their archives: the making of covidmemory project
Brüll, Christoph UL

Scientific Conference (2020, June 30)

Detailed reference viewed: 39 (2 UL)
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See detailPolitiques de synchronisation dans les systèmes multi-agents distribués parallèles
Rousset, Alban UL; Breugnot, Paul; Herrmann, Bénédicte et al

in Rousset, Alban (Ed.) Politiques de synchronisation dans les systèmes multi-agents distribués parallèles (2020, June 29)

Among simulation or modelisation methods, multi-agent systems are an interesting candidate to simulate complex systems. As the size of the model's increases, the use of parallel multi-agent systems is ... [more ▼]

Among simulation or modelisation methods, multi-agent systems are an interesting candidate to simulate complex systems. As the size of the model's increases, the use of parallel multi-agent systems is mandatory but comes with many issues. In this article, we are interested in the impact of synchronization on models design and on their execution. We highlight synchronization problems through model instances then we experimentally analyze the impact of synchronization on large scale test cases. [less ▲]

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See detailSTEAM in special needs education in an elementary school in Luxemburg
Haas, Ben; Lavicza, Zsolt; Kreis, Yves UL

Scientific Conference (2020, June 25)

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See detailInnovative uses of technologies for STEAM education in elementary schools in Luxemburg
Haas, Ben; Kreis, Yves UL

Scientific Conference (2020, June 23)

Detailed reference viewed: 81 (4 UL)
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See detailPIAF: Developing Computational and Algorithmic Thinking in Fundamental Education
Parmentier, Yannick; Reuter, Robert UL; Higuet, Sarah et al

in Proceedings of EdMedia + Innovate Learning (2020, June 23), 2020(1), 315-322

In this article, we present the objectives and first achievements of the PIAF project supported by the European Union and aiming at developing computational and algorithmic thinking in basic education ... [more ▼]

In this article, we present the objectives and first achievements of the PIAF project supported by the European Union and aiming at developing computational and algorithmic thinking in basic education. This project brings together researchers in educational sciences and computer science from four countries (Belgium, France, Germany and Luxembourg) around the theme of teacher training. More concretely, the aim is to define a framework (competency framework, pedagogical scenarios) enabling teachers to (i) appropriate the concept of computational and algorithmic thinking and (ii) implement learning activities that promote the development of this kind of thinking in children. [less ▲]

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See detailDevelopment of innovative concrete mixtures aggregates
Chewe Ngapeya, Gelen Gael UL; Waldmann, Daniele UL

Scientific Conference (2020, June 22)

Detailed reference viewed: 85 (7 UL)
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See detailDecision Triggered Data Transmission and Collection in Industrial Internet of Things
He, Jiguang; Kong, Long UL; Frondelius, Tero et al

in 2020 IEEE Wireless Communications and Networking Conference (WCNC) (2020, June 19)

We propose a decision triggered data transmission and collection (DTDTC) protocol for condition monitoring and anomaly detection in the industrial Internet of things (IIoT). In the IIoT, the collection ... [more ▼]

We propose a decision triggered data transmission and collection (DTDTC) protocol for condition monitoring and anomaly detection in the industrial Internet of things (IIoT). In the IIoT, the collection, processing, encoding, and transmission of the sensor readings are usually not for the reconstruction of the original data but for decision making at the fusion center. By moving the decision making process to the local end devices, the amount of data transmission can be significantly reduced, especially when normal signals with positive decisions dominate in the whole life cycle and the fusion center is only interested in collecting the abnormal data. The proposed concept combines compressive sensing, machine learning, data transmission, and joint decision making. The sensor readings are encoded and transmitted to the fusion center only when abnormal signals with negative decisions are detected. All the abnormal signals from the end devices are gathered at the fusion center for a joint decision with feedback messages forwarded to the local actuators. The advantage of such an approach lies in that it can significantly reduce the volume of data to be transmitted through wireless links. Moreover, the introduction of compressive sensing can further reduce the dimension of data tremendously. An exemplary case, i.e., diesel engine condition monitoring, is provided to validate the effectiveness and efficiency of the proposed scheme compared to the conventional ones. [less ▲]

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See detailParallel coupling strategy for multi-physics applications in eXtended Discrete Element Method
Besseron, Xavier UL; Rousset, Alban UL; Mainassara Chekaraou, Abdoul Wahid UL et al

Scientific Conference (2020, June 18)

Multi-physics problems containing discrete particles interacting with fluid phases are widely used industry for example in biomass combustion on a moving grate, particle sedimentation, iron production ... [more ▼]

Multi-physics problems containing discrete particles interacting with fluid phases are widely used industry for example in biomass combustion on a moving grate, particle sedimentation, iron production within a blast furnace, and selective laser melting for additive manufacturing. The eXtended Discrete Element Method (XDEM) uses a coupled Eulerian-Lagrangian approach to simulate these complex phenomena, and relies on the Discrete Element Method (DEM) to model the particle phase and Computational Fluid Dynamics (CFD) for the fluid phases, solved respectively with XDEM and OpenFOAM. However, such simulations are very computationally intensive. Additionally, because the DEM particles move within the CFD phases, a 3D volume coupling is required, hence it represents an important amount of data to be exchanged. This volume of communication can have a considerable impact on the performance of the parallel execution. To address this issue, XDEM has proposed a coupling strategy relying on a co-located partitioning. This approach coordinates the domain decomposition of the two independent solvers, XDEM and OpenFOAM, to impose some co-location constraints and reduce the overhead due to the coupling data exchange. This strategy for the parallel coupling of CFD-DEM has been evaluated to perform large scale simulations of debris within a dam break flow. [less ▲]

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See detailNational responses to date during the COVID-19 crisis in the areas of migration and asylum
Sommarribas, Adolfo UL

Scientific Conference (2020, June 17)

The COVID-19 took by surprise most Member States of the European Union, as they underestimated the rapid spread of the contagion in the continent. The response of the Member States was asymmetrical ... [more ▼]

The COVID-19 took by surprise most Member States of the European Union, as they underestimated the rapid spread of the contagion in the continent. The response of the Member States was asymmetrical, individualistic and significantly slow. The first measures taken were to close down the internal borders. The response of the European Union was even slower to the point that and it was not until March 17th 2020 that the external borders were closed. These actions affected legal migration into the European Union from four perspectives: 1) it affected the mobility of those third country nationals who were on temporary stay in the Member States; 2) the entry of third country nationals to do seasonal work; 3) the entry and stay of legal migrants; and 4) the status quo of the third country nationals already residing in the Member States, especially those who have a loss of income. This article will deal with the measures taken by Member States on who to manage the immigration services during the crisis as well as the measures taken in order to deal with overstayers, seasonal workers and other legal migrants. Finally, we will focus in the vulnerable situation that third-country national salaried workers are exposed due to the loss of income or loss of employment in the Member States and the risk of being returned to their country of origin. This presentation will also analyse the access to unemployment benefits. [less ▲]

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See detailSupporting Citizens’ Political Decision-Making Using Information Visualisation
Graf, Vanessa; Graf-Drasch, Valerie; Tiefenbeck, Verena et al

in Proceedings of the 28th European Conference on Information Systems (ECIS) (2020, June 17)

Individual decision-making is a complex process. If carried out by individual citizens in the context of politically relevant decisions, serious consequences at all levels of a society might occur. That ... [more ▼]

Individual decision-making is a complex process. If carried out by individual citizens in the context of politically relevant decisions, serious consequences at all levels of a society might occur. That is why these decisions need to be made with care and preferably on a broad set of information to reflect citizens’ true preferences. However, due to limited attention, citizens often consider only salient aspects in their decision-making. To mitigate unwanted consequences following therefrom, citizens are in dire need of decision-support. We address this need by developing an Information Systems (IS) tool. Being based on information visualisation, our tool supports citizens by providing instant feedback. To ensure a meaningful engagement, the IS tool is designed according to gamification principles. A first instantiation in the context of renewable energy acceptance in Germany yields three key findings: First, we find indications that young, urban, and environmentally aware citizens are willing to accept a high percentage of renewable wind energy. Second, we find that the tool influences citizens’ decision-making. Third, we find citizens to update, however not completely turn over their preferred level of renewable wind energy after interaction with the tool. This holds true across different cross-sections of the population. [less ▲]

Detailed reference viewed: 71 (0 UL)
See detailNetworked Governance, Enabling Multistakeholder Cooperation
Van Weyenbergh, Gael; Bouillard, Maxime; Wieneke, Lars UL et al

Scientific Conference (2020, June 12)

This workshop gathering 10 participants focused on finding the root cause for the need and purpose for multistakeholder cooperation between social scientists and civil society.

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See detailToward Metacognitive Radars: Concept and Applications
Mishra, K. V.; Shankar, M. R. B.; Ottersten, Björn UL

in 2020 IEEE International Radar Conference (RADAR), Toward Metacognitive Radars: Concept and Applications (2020, June 11)

We introduce a metacognitive approach to optimize the radar performance for a dynamic wireless channel. Similar to the origin of the cognitive radar in the neurobiological concept of cognition ... [more ▼]

We introduce a metacognitive approach to optimize the radar performance for a dynamic wireless channel. Similar to the origin of the cognitive radar in the neurobiological concept of cognition, metacognition also originates from neurobiological research on problem-solving and learning. Broadly defined as the process of learning to learn, metacognition improves the application of knowledge in domains beyond the immediate context in which it was learned. We describe basic features of a metacognitive radar and then illustrate its application with some examples such as antenna selection and resource sharing between radar and communications. Unlike previous works in communications that only focus on combining several existing algorithms to form a metacognitive radio, we also show the transfer of knowledge in a metacognitive radar. A metacognitive radar improves performance over individual cognitive radar algorithms, especially when both the channel and transmit/receive hardware are changed. [less ▲]

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See detailDiscovering Everyday Mathematical Situations Outside the Classroom with MathCityMap and GeoGebra 3D
Lavicza, Zsolt; Haas, Ben; Kreis, Yves UL

in Ludwig, Matthias; Jablonski, Simone; Caldeira, Amélia (Eds.) et al Research on Outdoor STEM Education in the digiTal Age: Proceedings of the ROSETA Online Conference in June 2020 (2020, June 10)

In elementary school, teaching and learning activities aim to develop, among others, students’ skills to acquire deeper understanding of their living environments. There are numerous opportunities for ... [more ▼]

In elementary school, teaching and learning activities aim to develop, among others, students’ skills to acquire deeper understanding of their living environments. There are numerous opportunities for students to recognize forms, shapes, and mathematical connections in everyday situations. These everyday situations can be simulated in classrooms; however, educational technologies offer new approaches to extend classroom activities, teachers can simulate and design shapes through Augmented Reality and 3D printing within or beyond the classroom. To stimulate students’ everyday mathematical connections utilizing these technologies could assist in developing activities outside the classroom in urban or in natural environments. Through this approach students could utilize or enhance their mathematical and technical skills within their usual living environments. Utilising educational software such as MathCityMap, GeoGebra 3D Calculator, and other 3D modelling software we developed examples of tasks that could offer easy transitions from in- to out-side of classrooms. In this paper, we will describe learning and teaching aims of these tasks and outline further research and development directions to broaden opportunities to develop students’ mathematical, design and modelling skills. [less ▲]

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See detailThe rise of eBPF for non-intrusive performance monitoring
Cassagnes, Cyril UL; Trestioreanu, Lucian Andrei UL; Joly, Clement UL et al

in IEEE Xplore (2020, June 08)

In this paper, we explain that container engines are strengthening their isolation mechanisms. Therefore, nonintrusive monitoring becomes a must-have for the performance analysis of containerized user ... [more ▼]

In this paper, we explain that container engines are strengthening their isolation mechanisms. Therefore, nonintrusive monitoring becomes a must-have for the performance analysis of containerized user-space application in production environments. After a literature review and background of Linux subsystems and container isolation concepts, we present our lessons learned of using the extended Berkeley packet filter to monitor and profile performance. We carry out the profiling and tracing of several Interledger connectors using two full-fledged implementations of the Interledger protocol specifications. [less ▲]

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See detailA Novel Heap-based Pilot Assignment for Full Duplex Cell-Free Massive MIMO with Zero-Forcing
Nguyen, Van Hieu; Nguyen, van Dinh UL; Dobre, Octavia A. et al

in IEEE International Conference on Communications (2020, June 07)

This paper investigates the combined benefits of full-duplex (FD) and cell-free massive multiple-input multipleoutput (CF-mMIMO), where a large number of distributed access points (APs) having FD ... [more ▼]

This paper investigates the combined benefits of full-duplex (FD) and cell-free massive multiple-input multipleoutput (CF-mMIMO), where a large number of distributed access points (APs) having FD capability simultaneously serve numerous uplink and downlink user equipments (UEs) on the same time-frequency resources. To enable the incorporation of FD technology in CF-mMIMO systems, we propose a novel heapbased pilot assignment algorithm, which not only can mitigate the effects of pilot contamination but also reduce the involved computational complexity. Then, we formulate a robust design problem for spectral efficiency (SE) maximization in which the power control and AP-UE association are jointly optimized, resulting in a difficult mixed-integer nonconvex programming. To solve this problem, we derive a more tractable problem before developing a very simple iterative algorithm based on inner approximation method with polynomial computational complexity. Numerical results show that our proposed methods with realistic parameters significantly outperform the existing approaches in terms of the quality of channel estimate and SE. [less ▲]

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See detailToward an SDN-based Data Collection Scheme for Vehicular Fog Computing
Boualouache, Abdelwahab UL; Soua, Ridha UL; Engel, Thomas UL

in IEEE International Conference on Communications ICC'2020 (2020, June 07)

With the integration of fog networks and vehicular networks, Vehicular Fog Computing (VFC) is a promising paradigm to efficiently collect data for improving safety, mobility, and driver experience during ... [more ▼]

With the integration of fog networks and vehicular networks, Vehicular Fog Computing (VFC) is a promising paradigm to efficiently collect data for improving safety, mobility, and driver experience during journeys. To this end, we exploit the Software-Defined Networking (SDN) paradigm to propose a fully-programmable, self-configurable, and context-aware data collection scheme for VFC. This scheme leverages a stochastic model to dynamically estimate the number of fog stations to be deployed. Our simulation results demonstrate that our proposed scheme provides lower latency and higher resiliency compared to classical data collection schemes. [less ▲]

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See detailThe relevance of risk disclosure and the role of readability and comparability
Weber, Véronique UL; Muessig, Anke UL

Scientific Conference (2020, June 05)

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See detailIdentifiability of Finite Mixture Models
Noel, Cédric; Schiltz, Jang UL

Scientific Conference (2020, June 04)

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See detailTrajeR an R package for the clustering of longitudinal data
Noel, Cédric; Schiltz, Jang UL

Scientific Conference (2020, June 04)

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See detailDebugging Inputs
Kirschner, Lukas; Soremekun, Ezekiel UL; Zeller, Andreas

in Proceedings of the ACM/IEEE 42nd International Conference on Software Engineering (2020, June)

When a program fails to process an input, it need not be the program code that is at fault. It can also be that the input data is faulty, for instance as result of data corruption. To get the data ... [more ▼]

When a program fails to process an input, it need not be the program code that is at fault. It can also be that the input data is faulty, for instance as result of data corruption. To get the data processed, one then has to debug the input data—that is, (1) identify which parts of the input data prevent processing, and (2) recover as much of the (valuable) input data as possible. In this paper, we present a general-purpose algorithm called ddmax that addresses these problems automatically. Through experiments, ddmax maximizes the subset of the input that can still be processed by the program, thus recovering and repairing as much data as possible; the difference between the original failing input and the “maximized” passing input includes all input fragments that could not be processed. To the best of our knowledge, ddmax is the first approach that fixes faults in the input data without requiring program analysis. In our evaluation, ddmax repaired about 69% of input files and recovered about 78% of data within one minute per input. [less ▲]

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See detailSuccessive Convex Approximation for Transmit Power Minimization in SWIPT-Multicast Systems
Gautam, Sumit UL; Lagunas, Eva UL; Kisseleff, Steven UL et al

Scientific Conference (2020, June)

We propose a novel technique for total transmit power minimization and optimal precoder design in wireless multi-group (MG) multicasting (MC) systems. The considered framework consists of three different ... [more ▼]

We propose a novel technique for total transmit power minimization and optimal precoder design in wireless multi-group (MG) multicasting (MC) systems. The considered framework consists of three different systems capable of handling heterogeneous user types viz., information decoding (ID) specific users with conventional receiver architectures, energy harvesting (EH) only users with non-linear EH module, and users with joint ID and EH capabilities having separate units for the two operations, respectively. Each user is categorized under unique group(s), which can be of MC type specifically meant for ID users, and/or an energy group consisting of EH explicit users. The joint ID and EH users are a part of the (last) EH group as well as any one of the MC groups distinctly. In this regard, we formulate an optimization problem to minimize the total transmit power with optimal precoder designs for the three aforementioned scenarios, under constraints on minimum signal-to-interference-plus-noise ratio and harvested energy by the users with respective demands. The problem may be adapted to the well-known semi-definite program, which can be typically solved via relaxation of rank-1 constraint. However, the relaxation of this constraint may in some cases lead to performance degradation, which increases with the rank of the solution obtained from the relaxed problem. Hence, we develop a novel technique motivated by the feasible-point pursuit and successive convex approximation method in order to address the rank-related issue. The benefits of the proposed method are illustrated under various operating conditions and parameter values, with comparison between the three above-mentioned scenarios. [less ▲]

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See detailEnhancing CoAP Group Communication to Support mMTC Over Satellite Networks
Soua, Ridha UL; Palattella, Maria Rita UL; Stemper, André UL et al

in IEEE International Conference on Communications (ICC) (2020, June)

Massive MTC (mMTC) is one of the application scenarios that upcoming 5G networks are expected to support. Satellites come into play in mMTC to complement and extend terrestrial networks in under-served ... [more ▼]

Massive MTC (mMTC) is one of the application scenarios that upcoming 5G networks are expected to support. Satellites come into play in mMTC to complement and extend terrestrial networks in under-served areas, where several services can benefit from the adoption of a group communication model. The IETF has specifically standardized the usage of CoAP group communication. However, CoAP responses are still sent in unicast from each single CoAP server to the CoAP client, which results in a substantial traffic load. Such problem becomes more severe in integrated IoT-Satellite networks given the limited bandwidth of the satellite return channel and the large number of IoT devices in a mMTC scenario. To reduce network traffic overhead in group communication and improve the network responsiveness, this paper proposes an aggregation scheme for the CoAP group communication in combination with Observer pattern and proxying. Results obtained by using the openSAND emulator and CoAPthon library corroborate the merit of our optimization in terms of overhead reduction and delay. [less ▲]

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See detailAn Integrated Teleoperation Assistance System for Collision Avoidance of High-speed UAVs in Complex Environments
Wang, Min UL; Voos, Holger UL

in 17th International Conference on Ubiquitous Robots (UR), Kyoto 22-26 June 2020 (2020, June)

UAV teleoperation is a demanding task, especially for amateur operators who wish to successfully accomplish their mission without collision. In this work we present an integrated 2D LIDAR based Sense-and ... [more ▼]

UAV teleoperation is a demanding task, especially for amateur operators who wish to successfully accomplish their mission without collision. In this work we present an integrated 2D LIDAR based Sense-and-Avoid system which actively assists unskilled human operator in obstacle avoidance, so that the operator can focus on higher-level decisions and global objectives in UAV applications such as search and rescue, farming etc. Specifically, with our perception-assistive vehicle control design, novel adaptive virtual cushion force field (AVCFF) based avoidance strategy, and integrated sensing solution, the proposed UAV teleoperation assistance system is capable of obstacle detection and tracking, as well as automatic avoidance in complex environment where both static and dynamic objects are present. The proposed system is constructed on the basis of Hector Quadrotor open source framework [1], and its effectiveness is demonstrated and validated on a realistic simulated UAV platform in Gazebo simulations where the UAV is operated at a high speed. [less ▲]

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See detailPerceptive Packet Scheduling for Carrier Aggregation in Satellite Communication Systems
Al-Hraishawi, Hayder UL; Maturo, Nicola UL; Lagunas, Eva UL et al

in IEEE International Conference on Communications, June 2020. (2020, June)

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See detailPractical Posterior Error Bounds from Variational Objectives
Huggins, Jonathan; Kasprzak, Mikolaj UL; Campbell, Trevor et al

in Proceedings of the 23rd International Conference on Artificial Intelligence and Statistics (AISTATS) (2020, June)

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See detailPredicting near-optimal skin distance in Verlet buffer approach for Discrete Element Method
Mainassara Chekaraou, Abdoul Wahid UL; Besseron, Xavier UL; Rousset, Alban UL et al

in 10th IEEE Workshop on Parallel / Distributed Combinatorics and Optimization (2020, June)

The Verlet list method is a well-known bookkeeping technique of the interaction list used both in Molecular Dynamic (MD) and Discrete Element Method (DEM). The Verlet buffer technique is an enhancement of ... [more ▼]

The Verlet list method is a well-known bookkeeping technique of the interaction list used both in Molecular Dynamic (MD) and Discrete Element Method (DEM). The Verlet buffer technique is an enhancement of the Verlet list that consists of extending the interaction radius of each particle by an extra margin to take into account more particles in the interaction list. The extra margin is based on the local flow regime of each particle to account for the different flow regimes that can coexist in the domain. However, the choice of the near-optimal extra margin (which ensures the best performance) for each particle and the related parameters remains unexplored in DEM unlike in MD. In this study, we demonstrate that the near-optimal extra margin can fairly be characterized by four parameters that describe each particle local flow regime: the particle velocity, the ratio of the containing cell size to particle size, the containing cell solid fraction, and the total number of particles in the system. For this purpose, we model the near-optimal extra margin as a function of these parameters using a quadratic polynomial function. We use the DAKOTA SOFTWARE to carry out the Design and Analysis of Computer Experiments (DACE) and the sampling of the parameters for the simulations. For a given instance of the set of parameters, a global optimization method is considered to find the near-optimal extra margin. The latter is required for the construction of the quadratic polynomial model. The numerous simulations generated by the sampling of the parameter were performed on a High-Performance Computing (HPC) environment granting parallel and concurrent executions. This work provides a better understanding of the Verlet buffer method in DEM simulations by analyzing its performances and behavior in various configurations. The near-optimal extra margin can reasonably be predicted by two out of the four chosen parameters using the quadratic polynomial model. This model has been integrated into XDEM in order to automatically choose the extra margin without any input from the user. Evaluations on real industrial-level test cases show up to a 26% reduction of the execution time. [less ▲]

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See detailImplicit Attitudes and Beliefs about Diversity (Cancelled due to COVID-19)
Stogianni, Maria UL; Grohmann, Lara; Kremer, Marina et al

Poster (2020, June)

Short abstract: The study examined attitudes towards multiculturalism in two European countries (Germany and Luxembourg). The findings reveal a positive relationship between implicit and explicit ... [more ▼]

Short abstract: The study examined attitudes towards multiculturalism in two European countries (Germany and Luxembourg). The findings reveal a positive relationship between implicit and explicit attitudes. Between group differences in the endorsement of diversity ideologies can be attributed to personality and biographical factors. [less ▲]

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See detailGOING DEEPER WITH NEURAL NETWORKS WITHOUT SKIP CONNECTIONS
Oyedotun, Oyebade UL; Shabayek, Abd El Rahman UL; Aouada, Djamila UL et al

in IEEE International Conference on Image Processing (ICIP 2020), Abu Dhabi, UAE, Oct 25–28, 2020 (2020, May 30)

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See detailBoosting SWIPT via Symbol-Level Precoding
Gautam, Sumit UL; Krivochiza, Jevgenij UL; Haqiqatnejad, Alireza UL et al

Scientific Conference (2020, May 29)

In this paper, we investigate a simultaneous wireless information and power transmission (SWIPT) system, wherein a single multi-antenna transmitter serves multiple single-antenna users which employ the ... [more ▼]

In this paper, we investigate a simultaneous wireless information and power transmission (SWIPT) system, wherein a single multi-antenna transmitter serves multiple single-antenna users which employ the power-splitting (PS) receiver architecture. We formulate a Symbol-Level Precoding (SLP) based transmit power minimization problem dependent on the minimum signal-to-interference-plus-noise ratio (SINR) and energy harvesting (EH) thresholds. We solve the corresponding non-negative convex quadratic optimization problem per time frame of transmitted symbols and study the benefits of proposed design under Zero-Forcing (ZF) Precoding, Direct Demand SLP (DD-SLP), and Squared-Root Demand SLP (RD-SLP) techniques. A static PS-ratio is fixed according to the SINR and EH demands to enable the segregation of intended received signals for information decoding (ID) and EH, respectively. Numerical results show the property conservation of SINR-enhancement via SLP at the ID unit while increasing the harvested energy at each of the end-users. [less ▲]

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See detailZur Bedeutsamkeit des Sportunterrichtes: Der Einfluss der Motivation im Sportunterricht auf den außerschulischen Kontext - ein longitudinaler Ansatz
Hutmacher, Djenna UL; Eckelt, Melanie UL; Bund, Andreas UL et al

Scientific Conference (2020, May 22)

Hintergrund: Hinsichtlich der kontinuierlichen Abnahme der körperlichen Aktivität von Kindern und Jugendlichen, rückt die Stärkung der Motivation als Ansatz zur Sportaktivierung immer mehr in den Fokus ... [more ▼]

Hintergrund: Hinsichtlich der kontinuierlichen Abnahme der körperlichen Aktivität von Kindern und Jugendlichen, rückt die Stärkung der Motivation als Ansatz zur Sportaktivierung immer mehr in den Fokus (Standage, Duda, & Ntoumanis, 2005). In ihrem trans-kontextuellen Modell postulieren Hagger und Chatzisarantis (2016) einen Zusammenhang zwischen intrinsischer Motivation im Sportunterricht und in der Freizeit. Dabei spielt die Unterstützung der Bedürfnisse durch die Sportlehrkraft eine wichtige Rolle, um die intrinsische Motivation der SchülerInnen im Sportunterricht und längerfristig in der Freizeit zu fördern, welche ein selbstbestimmtes körperliches Aktivitätsverhalten begünstigen soll. In der vorliegenden Studie wurden diese Annahmen in erweiterter Form im Längsschnitt geprüft. Methode: Es wurden N = 1681 SchülerInnen zwischen 10 und 23 Jahren (M = 14.7 Jahre; 50.7% weiblich) aus 14 luxemburgischen Schulen zu Beginn des Schuljahres (t1) und sechs Monate später am Ende des Schuljahres (t2) getestet. Neben der wahrgenommenen Bedürfnisunterstützung (Standage, Duda, & Ntoumanis, 2005) wurden die Motivationsregulation im Sportunterricht (PLOC-R; Vlachopoulos, Katartzi, Kontou, Moustaka, & Goudas, 2011) und in der Freizeit (BREQ-II; Markland & Tobin, 2004), sowie alle Konstrukte der Theorie des geplanten Handelns (Ajzen, 1991), und die körperliche Aktivität erhoben. Ergebnisse: Cross-Lagged-Panel Analysen zeigen, dass die intrinsische Motivation im Sportunterricht (t1) kontextübergreifend die intrinsische Motivation zur körperlichen Aktivität in der Freizeit (t2) vorhersagt (β = .12, p < .05). Selbiger Befund konnte auch für die Amotivation gefunden werden (β = .15, p < .05). Allerdings wurde kein kontextübergreifender Zusammenhang der extrinsischen Motivation gefunden (p > .05). Entgegen der postulierten Richtung des Modells, sagt eine höhere intrinsische Motivation der SchülerInnen (t1) eine höhere Wahrnehmung der Unterstützung der Grundbedürfnisse durch den Sportlehrer (t2) vorher (β = .10, p < .05). Die intrinsische Motivation in der Freizeit (t1) hängt zudem mit der Einstellung (β = .24, p < .05), subjektiven Norm (β = .11, p < .05), wahrgenommenen Verhaltenskontrolle (β = .12, p < .05), Intention (β = .16, p < .05) und der körperlichen Aktivität (β = .18, p < .05) zu t2 zusammen. Schlussfolgerung: Die Befunde bestätigen die Bedeutsamkeit des Sportunterrichts in dem Sinne, dass die intrinsische Motivation im Sportunterricht die Wahrnehmung der Bedürfnisunterstützung des Sportlehrers erhöht und kontextübergreifend mit der intrinsischen Motivation im Freizeitbereich zusammenhängt, welche wiederum ein selbstbestimmtes körperliches Aktivitätsverhalten in der Freizeit positiv bedingt. Eine Interventionsstudie im Sportunterricht bekräftigt diese Befunde in dem Sinne, dass die Autoren positivere Effekte fanden, wenn, zusätzlich zur alleinigen Autonomieunterstützung, internale Zielsetzungen in der Lehre eingesetzt wurden (Cheon, Reeve, & Song, 2019). [less ▲]

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See detailInformation Theoretic Approach for Waveform Design in Coexisting MIMO Radar and MIMO Communications
Alaeekerahroodi, Mohammad UL; Mysore Rama Rao, Bhavani Shankar UL; Mishra, Kumar Vijay et al

in Information Theoretic Approach for Waveform Design in Coexisting MIMO Radar and MIMO Communications (2020, May 14)

We investigate waveform design for coexistence between a multipleinput multiple-output (MIMO) radar and MIMO communications (MRMC), with a radar-centric criterion that leads to a minimal interference in ... [more ▼]

We investigate waveform design for coexistence between a multipleinput multiple-output (MIMO) radar and MIMO communications (MRMC), with a radar-centric criterion that leads to a minimal interference in the communications system. The communications use the traditional mode of operation in Long Term Evolution (LTE)/Advanced (FDD), where we formulate the design problem based on information-theoretic criterion with the discrete phase constraint at the design stage. The optimization problem, is nonconvex, multi-objective and multi-variable, where we propose an efficient algorithm based on the coordinate descent (CD) framework to simultaneously improve radar target detection performance and the communications rate. The numerical results indicate the effectiveness of the proposed algorithm in designing discrete phase set of sequences, potentially binary. [less ▲]

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See detailDeep Rainrate Estimation from Highly Attenuated Downlink Signals of Ground-Based Communications Satellite Terminals
Mishra, K. V.; R., B. S. M.; Ottersten, Björn UL

in ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), Deep Rainrate Estimation from Highly Attenuated Downlink Signals of Ground-Based Communications Satellite Terminals (2020, May 14)

While the use of weather radars to continuously monitor the spatiotemporal dynamics of precipitation has grown in recent years, these systems are expensive and sparsely deployed across the world. In this ... [more ▼]

While the use of weather radars to continuously monitor the spatiotemporal dynamics of precipitation has grown in recent years, these systems are expensive and sparsely deployed across the world. In this context, densely located ground-based terminals for interactive satellite services have the potential for dual-use as weather sensors because they measure rain-attenuated power of the downlink signal. Although in the millimeter-wave regime, the rain rate has almost a linear relationship with specific attenuation, lack of other weather radar observables at satellite terminals imposes a daunting task of extracting rainfall rate from these highly attenuated signals. We address this problem by designing a deep convolutional neural network (CNN) that learns the relationship between the signal attenuation and rainfall rate observed by weather radars and rain gauges at a given location. During the prediction stage, the CNN accepts downlink attenuation as input and classifies the rain intensity which is then used to apply an appropriate rainfall estimator. Our experiments with real data show that, despite severe attenuation, CNN-based downlink rainfall accumulations closely follow the nearest C-band German weather service Deutscher Wetterdienst (DWD) radar. [less ▲]

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See detailFlucht- und Wanderungsbewegungen in Ostbelgien 1944/45
Brüll, Christoph UL

Scientific Conference (2020, May 13)

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See detailClimate SMART Agriculture: How well does the agricultural sector in Luxembourg perform in terms of climate change?
Evelyne, Stoll; Schader, Christian; Bohn, Torsten et al

Scientific Conference (2020, May 04)

In Luxembourg, the agricultural sector was responsible for 711.7 Gg CO2-equivalents in 2016, which corresponds to 6.95 % of the total country greenhouse gas (GHG) emissions. Over 50 % of the farms are ... [more ▼]

In Luxembourg, the agricultural sector was responsible for 711.7 Gg CO2-equivalents in 2016, which corresponds to 6.95 % of the total country greenhouse gas (GHG) emissions. Over 50 % of the farms are specialist grazing livestock farms. The beef and cattle milk production account globally together for over 60 % of the sector’s global emissions. Thus, the climate impact of the whole agricultural sector in Luxembourg can be significantly lowered by reducing the GHG emissions of the specialist grazing livestock sector. However, beyond farm type, the GHG emissions of a farm are also influenced by other factors, such as management systems and farming practices. To enable a transition towards a more climate-positive agriculture, insights into the sustainability performance in terms of climate change are needed. The aim of this study is to determine the current sustainability performance of the Luxembourgish specialist grazing livestock sector in terms of climate change. The climate impact of the different specialist grazing livestock farm types (OTE (orientation technico-économique) 45 - Specialist dairying; OTE 46 - Specialist cattle - rearing and fattening and OTE 47 - Cattle - dairying, rearing and fattening combined) and of different management systems (conventional or organic) was assessed at farm-level. Furthermore, the relationship between the sustainability performance in terms of climate change and other areas of sustainability is being studied. Farming practices of 60 farms typical for Luxembourg in regard to their share of arable land and permanent grassland (OTE 45: 3 farms; OTE 46: 15; OTE 45: 11; Conventional: 44; Organic: 16) and their respective sustainability implications were assessed in 2019 according to the FAO SAFA Guidelines (Guidelines for the Sustainability Assessment of Food and Agriculture Systems, 2014) using the Sustainability Monitoring and Assessment RouTine (SMART)-Farm Tool (v5.0). Organic farms were highly overrepresented, with 26.7 % in the sample compared to 5 % of all Luxembourgish farms. The data was collected during a farm visit and a 3 h interview with the farm manager. The impact of management system and farm type on the SAFA-goal achievement for the sub-theme Greenhouse Gases (GHG) were studied. The results show that the sustainability performances of the participating farms were moderate to good. Goal achievement for the sub-theme GHG was moderate and did not differ significantly between the three farm types (OTE 45: 53.3 % ±3.9 SD goal achievement; OTE 46: 55.6 % ±7.3 SD; OTE 47: 54.6 % ±6.9 SD). Organic farms showed a significantly higher mean goal achievement for GHG than conventional farms (p-value < 0.001) (organic: 58.3 % ±6.0 SD; conventional: 52.6 % ±4.4 SD). For indicators positively impacting GHG, the organic and the OTE 46 farms had generally higher ratings. Correlations between GHG and the other sub-themes were mainly in the Environmental Integrity dimension, showing that implementing climate-positive farming practices can also improve other ecological aspects. The indicator analysis identified the following linchpins: increase in protein autarky, closing of farming cycles and holistic approach with strategic decision making leading to harmonized actions towards a sustainable and climate positive farming system. [less ▲]

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See detailSDN-based Misbehavior Detection System for Vehicular Networks
Boualouache, Abdelwahab UL; Soua, Ridha UL; Engel, Thomas UL

in 2020 IEEE 91st Vehicular Technology Conference (VTC2020-Spring) (2020, May)

Vehicular networks are vulnerable to a variety of internal attacks. Misbehavior Detection Systems (MDS) are preferred over the cryptography solutions to detect such attacks. However, the existing ... [more ▼]

Vehicular networks are vulnerable to a variety of internal attacks. Misbehavior Detection Systems (MDS) are preferred over the cryptography solutions to detect such attacks. However, the existing misbehavior detection systems are static and do not adapt to the context of vehicles. To this end, we exploit the Software-Defined Networking (SDN) paradigm to propose a context-aware MDS. Based on the context, our proposed system can tune security parameters to provide accurate detection with low false positives. Our system is Sybil attack-resistant and compliant with vehicular privacy standards. The simulation results show that, under different contexts, our system provides a high detection ratio and low false positives compared to a static MDS. [less ▲]

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See detailTransmit Beamforming Design with Received-Interference Power Constraints: The Zero-Forcing Relaxation
Lagunas, Eva UL; Perez-Neira, Ana; Lagunas, Miguel Angel et al

in IEEE Int. Conf. on Acoustics, Speech, and Signal Processing (ICASSP), Barcelona, Spain, May 2020 (2020, May)

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See detail'Faster-than-Nyquist Signaling via Spatiotemporal Symbol-Level Precoding for Multi-User MISO Redundant Transmissions
Alves Martins, Wallace UL; Spano, Danilo UL; Chatzinotas, Symeon UL et al

in International Conference on Acoustics, Speech, and Signal Processing (ICASSP-2020), Barcelona 4-8 May 2020 (2020, May)

This paper tackles the problem of both multi-user and intersymbol interference stemming from co-channel users transmitting at a faster-than-Nyquist (FTN) rate in multi-antenna downlink transmissions. We ... [more ▼]

This paper tackles the problem of both multi-user and intersymbol interference stemming from co-channel users transmitting at a faster-than-Nyquist (FTN) rate in multi-antenna downlink transmissions. We propose a framework for redundant block-based symbol-level precoders enabling the trade-off between constructive and destructive multi-user and interblock interference (IBI) effects at the single-antenna user terminals. Redundant elements are added as guard interval to handle IBI destructive effects. It is shown that, within this framework, accelerating the transmissions via FTN signaling improves the error-free spectral efficiency, up to a certain acceleration factor beyond which the transmitted information cannot be perfectly recovered by linear filtering followed by sampling. Simulation results corroborate that the proposed spatiotemporal symbol-level precoding can change the amount of added redundancy from zero (full IBI) to half (IBI-free) the equivalent channel order, so as to achieve a target balance between spectral and energy efficiencies. [less ▲]

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See detailComponent Analysis of Adjectives in Luxembourgish for Detecting Sentiments
Sirajzade, Joshgun UL; Gierschek, Daniela UL; Schommer, Christoph UL

in Beermann, Dorothee; Besacier, Laurent; Sakti, Sakriani (Eds.) et al Proceedings of the LREC 2020 1st Joint SLTU and CCURL Workshop(SLTU-CCURL 2020) (2020, May)

The aim of this paper is to investigate the role of Luxembourgish adjectives in expressing sentiments in user comments written at the web presence of rtl.lu (RTL is the abbreviation for Radio Television ... [more ▼]

The aim of this paper is to investigate the role of Luxembourgish adjectives in expressing sentiments in user comments written at the web presence of rtl.lu (RTL is the abbreviation for Radio Television Lëtzebuerg). Alongside many textual features or representations, adjectives could be used in order to detect sentiment, even on a sentence or comment level. In fact, they are also by themselves one of the best ways to describe a sentiment, despite the fact that other word classes such as nouns, verbs, adverbs or conjunctions can also be utilized for this purpose. The empirical part of this study focuses on a list of adjectives that were extracted from an annotated corpus. The corpus contains the part of speech tags of individual words and sentiment annotation on the adjective, sentence, and comment level. Suffixes of Luxembourgish adjectives like -esch, -eg, -lech, -al, -el, -iv, -ent, -los, -bar and the prefix on- were explicitly investigated, especially by paying attention to their role in regards to building a model by applying classical machine learning techniques. We also considered the interaction of adjectives with other grammatical means, especially other part of speeches, e.g. negations, which can completely reverse the meaning, thus the sentiment of an utterance. [less ▲]

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See detailBacAnalytics: A Tool to Support Secondary School Examination in France
Roussanaly, Azim; Aleksandrova, Marharyta UL; Boyer, Anne

in 25th International Symposium on Intelligent Systems (ISMIS 2020) (2020, May)

Students who failed the final examination in the secondary school in France (known as baccalauréat or baccalaureate) can improve their scores by passing a remedial test. This test consists of two oral ... [more ▼]

Students who failed the final examination in the secondary school in France (known as baccalauréat or baccalaureate) can improve their scores by passing a remedial test. This test consists of two oral examinations in two subjects of the student's choice. Students announce their choice on the day of the remedial test. Additionally, the secondary education system in France is quite complex. There exist several types of baccalaureate consisting of various streams. Depending upon the stream students belong to, they have different subjects allowed to be taken during the remedial test and different coefficients associated with each of them. In this context, it becomes difficult to estimate the number of professors of each subject required for the examination. Thereby, the general practice of remedial test organization is to mobilize a large number of professors. In this paper, we present BacAnalytics - a tool that was developed to assist the rectorate of secondary schools with the organization of remedial tests for the baccalaureate. Given profiles of students and their choices of subjects for previous years, this tool builds a predictive model and estimates the number of required professors for the current year. In the paper, we present the architecture of the tool, analyze its performance, and describe its usage by the rectorate of the Academy of Nancy-Metz in Grand Est region of France in the years 2018 and 2019. BacAnalytics achieves almost 100% of prediction accuracy with approximately 25% of redundancy and was awarded a French national prize Impulsions 2018. [less ▲]

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See detailTowards Power-Efficient Aerial Communicationsvia Dynamic Multi-UAV Cooperation
Xiang, Lin; Lei, Lei UL; Chatzinotas, Symeon UL et al

in IEEE Wireless Communications and Networking Conference (WCNC) 2020 (2020, May)

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See detailUnderstanding Moral Decision-Making in Video Games: A Focus Group Study
Holl, Elisabeth UL; Bernard, Steve UL; Melzer, André UL

Scientific Conference (2020, May)

Moral dilemmas have become increasingly popular in video games, although it is still widely unknown why players might find them pleasurable, how they process dilemmas, and which factors affect the ... [more ▼]

Moral dilemmas have become increasingly popular in video games, although it is still widely unknown why players might find them pleasurable, how they process dilemmas, and which factors affect the processing. Therefore, three different focus groups sessions with expert gamers (N = 16) were conducted. Gamers’ expressions of their experience with meaningful and morally relevant game situations were grouped for relevant topics. Topics are supported by direct quotations from participants of discussion groups, referring to up-to-date video game titles and presented together with respective theoretical assumptions. Results show that besides the game-defining theme of interactivity, statements can be grouped broadly into factors that describe why players engage or disengage in the first place (motivation) and factors that shape the moral interaction itself (influencing factors). In summary, our findings support the notion that moral-decision making in video games is a dynamic interplay between several game and user-dependent variables. Findings provide insights into players’ processing of moral dilemmas in video games, which also offers promising suggestions for future research using experimental setups. [less ▲]

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See detail3D DEFORMATION SIGNATURE FOR DYNAMIC FACE RECOGNITION
Shabayek, Abd El Rahman UL; Aouada, Djamila UL; Cherenkova, Kseniya UL et al

in 45th International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2020), Barcelona 4-8 May 2020 (2020, May)

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See detailSecurity and Performance Implications of BGP Rerouting-resistant Guard Selection Algorithms for Tor
Mitseva, Asya UL; Aleksandrova, Marharyta UL; Engel, Thomas UL et al

in Security and Performance Implications of BGP Rerouting-resistant Guard Selection Algorithms for Tor (2020, May)

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See detailDeep Learning for Beam Hopping in Multibeam Satellite Systems
Lei, Lei UL; Lagunas, Eva UL; Yuan, Yaxiong UL et al

in IEEE 91st Vehicular Technology Conference (VTC2020-Spring) (2020, May)

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See detailPlay the Pain Away: Pain Regulation and Attention in Virtual Reality
Holl, Elisabeth UL; Rischer, Katharina Miriam UL; Battistutta, Layla UL et al

Scientific Conference (2020, May)

Virtual reality (VR) has been shown to be a powerful method to divert attention away from pain (Malloy & Milling, 2010). In an ongoing study (data collection will be finished in late December 2019 ... [more ▼]

Virtual reality (VR) has been shown to be a powerful method to divert attention away from pain (Malloy & Milling, 2010). In an ongoing study (data collection will be finished in late December 2019) healthy participants play the VR game Subnautica in two conditions (high vs. low cognitive load). Pain thresholds and psychophysiological measures are assessed during play to measure the distraction effect. Additionally, pain management will be compared to individual executive functions and attention investigated before playing. [less ▲]

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See detailOn the Efficiency of Test Suite based Program Repair: A Systematic Assessment of 16 Automated Repair Systems for Java Programs
Liu, Kui UL; Wang, Shangwen; Koyuncu, Anil UL et al

in 42nd ACM/IEEE International Conference on Software Engineering (ICSE) (2020, May)

Test-based automated program repair has been a prolific field of research in software engineering in the last decade. Many approaches have indeed been proposed, which leverage test suites as a weak, but ... [more ▼]

Test-based automated program repair has been a prolific field of research in software engineering in the last decade. Many approaches have indeed been proposed, which leverage test suites as a weak, but affordable, approximation to program specifications. Although the literature regularly sets new records on the number of benchmark bugs that can be fixed, several studies increasingly raise concerns about the limitations and biases of state-of-the-art approaches. For example, the correctness of generated patches has been questioned in a number of studies, while other researchers pointed out that evaluation schemes may be misleading with respect to the processing of fault localization results. Nevertheless, there is little work addressing the efficiency of patch generation, with regard to the practicality of program repair. In this paper, we fill this gap in the literature, by providing an extensive review on the efficiency of test suite based program repair. Our objective is to assess the number of generated patch candidates, since this information is correlated to (1) the strategy to traverse the search space efficiently in order to select sensical repair attempts, (2) the strategy to minimize the test effort for identifying a plausible patch, (3) as well as the strategy to prioritize the generation of a correct patch. To that end, we perform a large-scale empirical study on the efficiency, in terms of quantity of generated patch candidates of the 16 open-source repair tools for Java programs. The experiments are carefully conducted under the same fault localization configurations to limit biases. Eventually, among other findings, we note that: (1) many irrelevant patch candidates are generated by changing wrong code locations; (2) however, if the search space is carefully triaged, fault localization noise has little impact on patch generation efficiency; (3) yet, current template-based repair systems, which are known to be most effective in fixing a large number of bugs, are actually least efficient as they tend to generate majoritarily irrelevant patch candidates. [less ▲]

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See detailPerformance Analysis of Distributed and Scalable Deep Learning
Mahon, S.; Varrette, Sébastien UL; Plugaru, Valentin UL et al

in 20th IEEE/ACM Intl. Symp. on Cluster, Cloud and Internet Computing (CCGrid'20) (2020, May)

With renewed global interest for Artificial Intelligence (AI) methods, the past decade has seen a myriad of new programming models and tools that enable better and faster Machine Learning (ML). More ... [more ▼]

With renewed global interest for Artificial Intelligence (AI) methods, the past decade has seen a myriad of new programming models and tools that enable better and faster Machine Learning (ML). More recently, a subset of ML known as Deep Learning (DL) raised an increased interest due to its inherent ability to tackle efficiently novel cognitive computing applications. DL allows computational models that are composed of multiple processing layers to learn in an automated way representations of data with multiple levels of abstraction, and can deliver higher predictive accuracy when trained on larger data sets. Based on Artificial Neural Networks (ANN), DL is now at the core of state of the art voice recognition systems (which enable easy control over e.g. Internet-of- Things (IoT) smart home appliances for instance), self-driving car engine, online recommendation systems. The ecosystem of DL frameworks is fast evolving, as well as the DL architectures that are shown to perform well on specialized tasks and to exploit GPU accelerators. For this reason, the frequent performance evaluation of the DL ecosystem is re- quired, especially since the advent of novel distributed training frameworks such as Horovod allowing for scalable training across multiple computing resources. In this paper, the scalability evaluation of the reference DL frameworks (Tensorflow, Keras, MXNet, and PyTorch) is performed over up-to-date High Performance Comput- ing (HPC) resources to compare the efficiency of differ- ent implementations across several hardware architectures (CPU and GPU). Experimental results demonstrate that the DistributedDataParallel features in the Pytorch library seem to be the most efficient framework for distributing the training process across many devices, allowing to reach a throughput speedup of 10.11 when using 12 NVidia Tesla V100 GPUs when training Resnet44 on the CIFAR10 dataset. [less ▲]

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See detailDynamic Adaptation of Software-defined Networks for IoT Systems: A Search-based Approach
Shin, Seung Yeob UL; Nejati, Shiva UL; Sabetzadeh, Mehrdad UL et al

in Proceedings of the 15th International Symposium on Software Engineering for Adaptive and Self-Managing Systems (SEAMS'20) (2020, May)

The concept of Internet of Things (IoT) has led to the development of many complex and critical systems such as smart emergency management systems. IoT-enabled applications typically depend on a ... [more ▼]

The concept of Internet of Things (IoT) has led to the development of many complex and critical systems such as smart emergency management systems. IoT-enabled applications typically depend on a communication network for transmitting large volumes of data in unpredictable and changing environments. These networks are prone to congestion when there is a burst in demand, e.g., as an emergency situation is unfolding, and therefore rely on configurable software-defined networks (SDN). In this paper, we propose a dynamic adaptive SDN configuration approach for IoT systems. The approach enables resolving congestion in real time while minimizing network utilization, data transmission delays and adaptation costs. Our approach builds on existing work in dynamic adaptive search-based software engineering (SBSE) to reconfigure an SDN while simultaneously ensuring multiple quality of service criteria. We evaluate our approach on an industrial national emergency management system, which is aimed at detecting disasters and emergencies, and facilitating recovery and rescue operations by providing first responders with a reliable communication infrastructure. Our results indicate that (1) our approach is able to efficiently and effectively adapt an SDN to dynamically resolve congestion, and (2) compared to two baseline data forwarding algorithms that are static and non-adaptive, our approach increases data transmission rate by a factor of at least 3 and decreases data loss by at least 70%. [less ▲]

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See detailAn Annotation Framework for Luxembourgish Sentiment Analysis
Sirajzade, Joshgun UL; Gierschek, Daniela UL; Schommer, Christoph UL

in Besacier, Laurent; Sakti, Sakriani; Soria, Claudia (Eds.) et al Proceedings of the LREC 2020 1st Joint SLTU and CCURL Workshop (SLTU-CCURL 2020) (2020, May)

The aim of this paper is to present a framework developed for crowdsourcing sentiment annotation for the low-resource language Luxembourgish. Our tool is easily accessible through a web interface and ... [more ▼]

The aim of this paper is to present a framework developed for crowdsourcing sentiment annotation for the low-resource language Luxembourgish. Our tool is easily accessible through a web interface and facilitates sentence-level annotation of several annotators in parallel. In the heart of our framework is an XML database, which serves as central part linking several components. The corpus in the database consists of news articles and user comments. One of the components is LuNa, a tool for linguistic preprocessing of the data set. It tokenizes the text, splits it into sentences and assigns POS-tags to the tokens. After that, the preprocessed text is stored in XML format into the database. The Sentiment Annotation Tool, which is a browser-based tool, then enables the annotation of split sentences from the database. The Sentiment Engine, a separate module, is trained with this material in order to annotate the whole data set and analyze the sentiment of the comments over time and in relationship to the news articles. The gained knowledge can again be used to improve the sentiment classification on the one hand and on the other hand to understand the sentiment phenomenon from the linguistic point of view. [less ▲]

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See detailProceedings of the 6th Global Conference on Artificial Intelligence (GCAI 2020)
Danoy, Grégoire UL; Pang, Jun UL; Sutcliffe

in 6th Global Conference on Artificial Intelligence (2020, May)

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See detailJoint Optimization for PS-based SWIPT Multiuser Systems with Non-linear Energy Harvesting
Vu, Thang Xuan UL; Chatzinotas, Symeon UL; Gautam, Sumit UL et al

in IEEE Wireless Communications and Networking Conference (WCNC), Seoul, 25-38 May 2020 (2020, May)

In this paper, we investigate the performance of simultaneous wireless information and power transfer (SWIPT) multiuser systems, in which a base station serves a set of users with both information and ... [more ▼]

In this paper, we investigate the performance of simultaneous wireless information and power transfer (SWIPT) multiuser systems, in which a base station serves a set of users with both information and energy simultaneously via a power splitting (PS) mechanism. To capture realistic scenarios, a nonlinear energy harvesting (EH) model is considered. In particular, we jointly design the PS factors and the beamforming vectors in order to maximize the total harvested energy, subjected to rate requirements and a total transmit power budget. To deal with the inherent non-convexity of the formulated problem, an iterative optimization algorithm is proposed based on the inner approximation method and semidefinite relaxation (SDR), whose convergence is theoretically guaranteed. Numerical results show that the proposed scheme significantly outperforms the baseline max-min based SWIPT multicast and fixed-power PS designs. [less ▲]

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See detailConstcamer Paintings as Epistemic Images: Early Modern Theaters of Wisdom
Koeleman, Floor UL

Scientific Conference (2020, April 04)

This paper argues, against existing literature, that 17th-cent. constcamer paintings were objects to think with, functioning as the two-dimensional space of artificial memory. In turn, these artworks ... [more ▼]

This paper argues, against existing literature, that 17th-cent. constcamer paintings were objects to think with, functioning as the two-dimensional space of artificial memory. In turn, these artworks complicate conventional definitions of epistemic images more broadly. I focus on an analysis of constcamer paintings accounting for the reception of the ancients and the mnemonic and propaedeutic role of images, entailing concepts such as wonder or thauma (from Greek θεάομαι), the drive to gather knowledge, memory as the locus of this ‘collection’, and recollecting as the intellectual process of interaction with memorized knowledge. The term inventor, referring to the creator of a given collection, is derived from the rhetorical technique for the retrieval of information. The theatre or ‘place for viewing’ provided the physical context for the collected wisdom. Inventors of constcamer paintings – often artists themselves – vitally participated in knowledge formation contributing to contemporary intellectual debates. [less ▲]

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See detailLOVBench: Ontology Ranking Benchmark
Kolbe, Niklas UL; Vandenbussche, Pierre-Yves; Kubler, Sylvain UL et al

in Proceedings of The Web Conference 2020 (WWW '20) (2020, April)

Detailed reference viewed: 49 (9 UL)
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See detailDoes Conscientiousness Matter for Academic Success? Considering Different Facets of Conscientiousness and Different Educational Outcomes
Franzen, Patrick UL; van der Westhuizen, Lindie UL; Arens, A. Katrin et al

Poster (2020, April)

Conscientiousness is the strongest BIG-5 predictor of academic success. Both conscientiousness and academic success are broad concepts, consisting of multiple lower level facets. Conscientiousness facets ... [more ▼]

Conscientiousness is the strongest BIG-5 predictor of academic success. Both conscientiousness and academic success are broad concepts, consisting of multiple lower level facets. Conscientiousness facets might display differential relations to different indicators of academic success. To investigate these relations, conscientiousness facets need to be measured in an economic and valid way. We conducted two studies, validating a short conscientiousness scale measuring seven facets of conscientiousness (Industriousness, Task Planning, Perfectionism, Procrastination Refrainment, Tidiness, Control, Cautiousness), and testing the relations of these facets with GPA, test scores, school satisfaction, and engagement. The results supported the validity of the scale. Industriousness, Perfectionism, and Cautiousness revealed the highest relations to academic outcomes. GPA and test scores showed differential associations with the different conscientiousness facets. [less ▲]

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See detailIntegrating Topological Proofs with Model Checking to Instrument Iterative Design
Menghi, Claudio UL; Rizzi, Alessandro Maria; Bernasconi, Anna

in Proceedings of the 23rd International Conference on Fundamental Approaches to Software Engineering, FASE 2020 (2020, April)

System development is not a linear, one-shot process. It proceeds through refinements and revisions. To support assurance that the system satisfies its requirements, it is desirable that continuous ... [more ▼]

System development is not a linear, one-shot process. It proceeds through refinements and revisions. To support assurance that the system satisfies its requirements, it is desirable that continuous verification can be performed after each refinement or revision step. To achieve practical adoption, formal verification must accommodate continuous verification efficiently and effectively. Model checking provides developers with information useful to improve their models only when a property is not satisfied, i.e., when a counterexample is returned. However, it is desirable to have some useful information also when a property is instead satisfied. To address this problem we propose TOrPEDO, an approach that supports verification in two complementary forms: model checking and proofs. While model checking is typically used to pinpoint model behaviors that violate requirements, proofs can instead explain why requirements are satisfied. In our work, we introduce a specific notion of proof, called Topological Proof. A topological proof produces a slice of the original model that justifies the property satisfaction. Because models can be incomplete, TOrPEDO supports reasoning on requirements satisfaction, violation, and possible satisfaction (in the case where satisfaction depends on unknown parts of the model). Evaluation is performed by checking how topological proofs support software development on 12 modeling scenarios and 15 different properties obtained from 3 examples from literature. Results show that: (i) topological proofs are ≈60% smaller than the original models; (ii) after a revision, in ≈78% of cases, the property can be re-verified by relying on a simple syntactic check. [less ▲]

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See detailPromoting Elementary-School Teachers’ Diagnostic Skills to Recognize their Students’ Academic Potential
Krischler, Mireille UL; Breit, Moritz; Preckel, Franzis

Poster (2020, April)

We present a five-year project aimed at improving teachers’ skills to detect mathematical and scientific talent in elementary school students. Within the project, teachers from 23 German schools and ... [more ▼]

We present a five-year project aimed at improving teachers’ skills to detect mathematical and scientific talent in elementary school students. Within the project, teachers from 23 German schools and researchers cooperate to extend teachers’ diagnostic competencies, substantiate their practices scientifically, and to learn from each other’s experiences in the detection and promotion of STEM talent (i.e. networked improvement community). The project is theoretically based on domain- specific talent development models for mathematics and natural science. In the course of the project, teachers interact with e-learning modules, participate in training sessions, attend workshops that bridge scientific theory and educational practice, and regularly evaluate these components of the project. We present the conceptualization of the project as well as first results. [less ▲]

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See detailProgramme Démence Prévention (pdp ): A Nation-Wide Programme for Dementia Prevention in Luxembourg
Schröder, Valerie UL; Kaysen, Anne UL; Fritz, Joëlle UL et al

Poster (2020, April)

Objectives: To implement a multi-year nation-wide programme, by the means of a personalised lifestyle intervention, to prevent or to delay cognitive decline that can contribute to development of dementia ... [more ▼]

Objectives: To implement a multi-year nation-wide programme, by the means of a personalised lifestyle intervention, to prevent or to delay cognitive decline that can contribute to development of dementia in Luxembourg. Methods: Participants with mild cognitive impairment, referred to the programme by their treating physician, undergo an extensive cognitive evaluation by a neuropsychologist on relevant neuropsychological domains as well as a structured dementia risk factor assessment. Based on these assessments, individualised lifestyle interventions are offered by diverse national partners involved in the programme, thus filling a gap of not yet reimbursed services in the Luxemburgish healthcare system. After the personalised lifestyle interventions, each participant will undergo a neuropsychological follow-up in order to re-evaluate his/her health status in terms of cognition. Results: We established a participant-centred national network by presenting the programme on many outreach events and efficient stakeholder communication. The network raises the awareness of dementia prevention in the Luxembourgish population, fosters interdisciplinary communication between individual medical and non-medical healthcare professionals and allows for a successful recruitment of the target population. Moreover, we collect information about adherence to the suggested lifestyle changes, as well as the effectiveness of our interventions in reducing risk factors contributing to the onset of dementia. Conclusions: We provide evidence for the feasibility of the implementation of a nation-wide dementia prevention programme including diverse partners offering personalised lifestyle interventions, which are easily transferrable to other countries. Future results from this programme may also help to integrate prevention interventions into the regular healthcare system. [less ▲]

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See detailMadDroid: Characterizing and Detecting Devious Ad Contents for Android Apps
Liu, Tianming; Wang, Haoyu; Li, Li et al

in Proceedings of The Web Conference 2020 (2020, April)

Advertisement drives the economy of the mobile app ecosystem. As a key component in the mobile ad business model, mobile ad content has been overlooked by the research community, which poses a number of ... [more ▼]

Advertisement drives the economy of the mobile app ecosystem. As a key component in the mobile ad business model, mobile ad content has been overlooked by the research community, which poses a number of threats, e.g., propagating malware and undesirable contents. To understand the practice of these devious ad behaviors, we perform a large-scale study on the app contents harvested through automated app testing. In this work, we first provide a comprehensive categorization of devious ad contents, including five kinds of behaviors belonging to two categories: ad loading content and ad clicking content. Then, we propose MadDroid, a framework for automated detection of devious ad contents. MadDroid leverages an automated app testing framework with a sophisticated ad view exploration strategy for effectively collecting ad-related network traffic and subsequently extracting ad contents. We then integrate dedicated approaches into the framework to identify devious ad contents. We have applied MadDroid to 40,000 Android apps and found that roughly 6% of apps deliver devious ad contents, e.g., distributing malicious apps that cannot be downloaded via traditional app markets. Experiment results indicate that devious ad contents are prevalent, suggesting that our community should invest more effort into the detection and mitigation of devious ads towards building a trustworthy mobile advertising ecosystem. [less ▲]

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See detailNeuere Methoden zur Identifikation und Lokalisierung von Schäden an vorgespannten Betonbrücken
Maas, Stefan UL; Nguyen, Viet Ha UL; Kebig, Tanja UL

in Bischoff, Manfred; von Scheven, Malte; Oesterle, Bernd (Eds.) Baustatik-Baupraxis 14 (2020, March 23)

Zuerst wird ein rein statistischer Schadensindikator basierend auf der Hauptkomponentenanalyse vorgestellt. Wichtig sind Referenzmessungen im ungeschädigten Zustand, um Veränderungen zu identifizieren ... [more ▼]

Zuerst wird ein rein statistischer Schadensindikator basierend auf der Hauptkomponentenanalyse vorgestellt. Wichtig sind Referenzmessungen im ungeschädigten Zustand, um Veränderungen zu identifizieren. Bevor die Messdaten mit den Rechenmodellen kombiniert werden, müssen Temperatureffekte kompensiert werden, um dann die Schäden zu erkennen und zu lokalisieren. Ein „Model-Updating“ Prozess eines speziellen Finite-Elemente- Modells passt die Steifigkeitsmatrix an die gemessenen Eigenfrequenzen oder an die progressive Absenkung unter Eigengewicht an. [less ▲]

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See detailGuided Inductive Logic Programming: Cleaning Knowledge Bases with Iterative User Feedback
Wu, Yan; Chen, Jinchuan; Haxhidauti, Plarent et al

in Guided Inductive Logic Programming: Cleaning Knowledge Bases with Iterative User Feedback (2020, March 12)

Domain-oriented knowledge bases (KBs) such as DBpedia and YAGO are largely constructed by applying a set of predefined extraction rules to the semi-structured contents of Wikipedia articles. Although both ... [more ▼]

Domain-oriented knowledge bases (KBs) such as DBpedia and YAGO are largely constructed by applying a set of predefined extraction rules to the semi-structured contents of Wikipedia articles. Although both of these large-scale KBs achieve very high average precision values (above 95% for YAGO3), subtle mistakes in a few of the underlying extraction rules may still impose a substantial amount of systematic extraction mistakes for specific relations. For example, by applying the same regular expressions to extract person names of both Asian and Western nationality, YAGO erroneously swaps most of the family and given names of Asian person entities. For traditional rule-learning approaches based on Inductive Logic Programming (ILP), it is very difficult to detect these systematic extraction mistakes, since they usually occur only in a relatively small subdomain of the relations’ arguments. In this paper, we thus propose a guided form of ILP, coined “GILP”, that iteratively asks for small amounts of user feedback over a given KB to learn a set of data-cleaning rules that (1) best match the feedback and (2) also generalize to a larger portion of facts in the KB. We propose both algorithms and respective metrics to automatically assess the quality of the learned rules with respect to the user feedback. [less ▲]

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See detailAgentenbasierte, hybride Steuerungsarchitektur für cyberphysische Refabrikationssysteme
Groß, Sebastian UL; Gerke, Wolfgang; Plapper, Peter UL

in Jäkel, Jens; Thiel, Robert (Eds.) Tagungsband AALE 2020 Automatisierung und Mensch-Technik-Interaktion (2020, March 05)

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See detailMensch-Roboter-Kollaboration in der Domäne Refabrikation – State-of-the-Art und Ausblick
Groß, Sebastian UL; Gerke, Wolfgang; Plapper, Peter UL

in Jäkel, Jens; Thiel, Robert (Eds.) Tagungsband AALE 2020 Automatisierung und Mensch-Technik-Interaktion (2020, March 05)

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See detailStructured Compression of Deep Neural Networks with Debiased Elastic Group LASSO
Oyedotun, Oyebade UL; Aouada, Djamila UL; Ottersten, Björn UL

in IEEE 2020 Winter Conference on Applications of Computer Vision (WACV 20), Aspen, Colorado, US, March 2–5, 2020 (2020, March 01)

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See detailAnalyzing PeerFlow -- A Bandwidth Estimation System for Untrustworthy Environments
Mitseva, Asya UL; Engel, Thomas UL; Panchenko, Andriy

in Analyzing PeerFlow -- A Bandwidth Estimation System for Untrustworthy Environments (2020, March)

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See detailInvestigating the role of individual differences in the analgesic response to a virtual reality game: An exploratory analysis (accepted submission, but symposium was cancelled due to COVID-19)
Rischer, Katharina Miriam UL; Barcatta, Katharina UL; Battistutta, Layla UL et al

Scientific Conference (2020, March)

Virtual reality (VR) has been shown to be a powerful method of redirecting attention away from pain and is increasingly used in clinical settings as a therapeutic tool for pain treatment. Yet, little is ... [more ▼]

Virtual reality (VR) has been shown to be a powerful method of redirecting attention away from pain and is increasingly used in clinical settings as a therapeutic tool for pain treatment. Yet, little is known about the underlying factors that modulate the size of the analgesic response to a VR game, such as task difficulty and inter-individual differences in pain attitude, emotion regulation habits, executive functions and virtual reality experience. Methods: 101 healthy participants played two versions of the VR game Subnautica, differing in cognitive load (low load vs. high load). In the low load condition, participants navigated along a predefined route. In the high load condition, participants additionally memorized a series of single digits presented along the route. Pain heat thresholds as well as psychophysiological measures (ECG, EDA) were recorded during a resting state period prior to, as well as during, the two VR playing sessions. In addition, participants completed several psychological questionnaires and different executive functioning tasks (Corsi block tapping task, flanker task, go/nogo task) prior to the VR sessions. Results: Preliminary results of a subgroup (N = 66) of the total sample revealed that pain thresholds were significantly higher for the VR playing sessions when compared to the resting state period, with a trend of a higher threshold for the high load condition. Moreover, pain catastrophizing and fear of pain were significant predictors of pain threshold measurements. The complete results will be presented at the symposium. Discussion: Results could shed light on the role of inter-individual differences on the efficacy of VR-based distraction from pain, and potentially elucidate factors that render an individual more likely to benefit from VR as a pain-relieving tool. This may have important consequences for the use of VR as a therapeutic treatment for pain patients. [less ▲]

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See detailTowards an Executable Methodology for the Formalization of Legal Texts
Libal, Tomer UL; Steen, Alexander UL

in Dastani, Mehdi; Dong, Huimin; van der Torre, Leon (Eds.) Logic and Argumentation. CLAR 2020 (2020, March)

A methodology for the formalization of legal texts is presented. This methodology is based on features of the NAI Suite, a recently developed formalization environment for legal texts. The ability of the ... [more ▼]

A methodology for the formalization of legal texts is presented. This methodology is based on features of the NAI Suite, a recently developed formalization environment for legal texts. The ability of the tool to execute queries is used in order to drive a correct formalization until all queries are validated. The approach is studied on a fragment of the Smoking Prohibition (Children in Motor Vehicles) (Scotland) Act 2016 of the Scottish Parliament. [less ▲]

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See detailLangzeiteffekte von Klassenwiederholungen in der Sekundarstufe
Klapproth, Florian; Keller, Ulrich UL; Fischbach, Antoine UL

Scientific Conference (2020, March)

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See detailDissecting Android Cryptocurrency Miners
Dashevskyi, Stanislav UL; Zhauniarovich, Yury; Gadyatskaya, Olga UL et al

in CODASPY '20: Tenth ACM Conference on Data and Application Security and Privacy, New Orleans LA USA, March 2020 (2020, March)

Cryptojacking applications pose a serious threat to mobile devices. Due to the extensive computations, they deplete the battery fast and can even damage the device. In this work we make a step towards ... [more ▼]

Cryptojacking applications pose a serious threat to mobile devices. Due to the extensive computations, they deplete the battery fast and can even damage the device. In this work we make a step towards combating this threat. We collected and manually verified a large dataset of Android mining apps. In this paper, we analyze the gathered miners and identify how they work, what are the most popular libraries and APIs used to facilitate their development, and what static features are typical for this class of applications. Further, we analyzed our dataset using VirusTotal. The majority of our samples is considered malicious by at least one VirusTotal scanner, but 16 apps are not detected by any engine; and at least 5 apks were not seen previously by the service. Mining code could be obfuscated or fetched at runtime, and there are many confusing miner-related apps that actually do not mine. Thus, static features alone are not sufficient for miner detection.We have collected a feature set of dynamic metrics both for miners and unrelated benign apps, and built a machine learning-based tool for dynamic detection. Our BrenntDroid tool is able to detect miners with 95% of accuracy on our dataset. [less ▲]

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See detailMetamorphic Security Testing for Web Systems
Mai, Xuan Phu UL; Pastore, Fabrizio UL; Goknil, Arda et al

in IEEE International Conference on Software Testing, Verification and Validation (ICST) 2020 (2020, March)

Security testing verifies that the data and the resources of software systems are protected from attackers. Unfortunately, it suffers from the oracle problem, which refers to the challenge, given an input ... [more ▼]

Security testing verifies that the data and the resources of software systems are protected from attackers. Unfortunately, it suffers from the oracle problem, which refers to the challenge, given an input for a system, of distinguishing correct from incorrect behavior. In many situations where potential vulnerabilities are tested, a test oracle may not exist, or it might be impractical due to the many inputs for which specific oracles have to be defined. In this paper, we propose a metamorphic testing approach that alleviates the oracle problem in security testing. It enables engineers to specify metamorphic relations (MRs) that capture security properties of the system. Such MRs are then used to automate testing and detect vulnerabilities. We provide a catalog of 22 system-agnostic MRs to automate security testing in Web systems. Our approach targets 39% of the OWASP security testing activities not automated by state-of-the-art techniques. It automatically detected 10 out of 12 vulnerabilities affecting two widely used systems, one commercial and the other open source (Jenkins). [less ▲]

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See detailNAI: Towards Transparent and Usable Semi-Automated Legal Analysis
Libal, Tomer UL; Steen, Alexander UL

in Schweighöfer, Erich; Hötzendorfer, Walter; Kummer, Franz (Eds.) et al Verantwortungsbewusste Digitalisierung, Tagungsband des 23. Internationalen Rechtsinformatik Symposions IRIS 2020 (2020, February 27)

A prototype for automated reasoning over legal documents, called NAI, is presented. It uses formalized representations of legal documents that are created using a graphical editor that is also provided as ... [more ▼]

A prototype for automated reasoning over legal documents, called NAI, is presented. It uses formalized representations of legal documents that are created using a graphical editor that is also provided as part of NAI. The prototype supports several automated reasoning procedures over the given formalizations, including the execution of user queries. The application of NAI is studied using a fragment of the Scottish Smoking Prohibition (Children in Motor Vehicles) Act 2016. [less ▲]

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See detailA Preliminary Study on the Automatic Visual based Identification of UAV Pilots from Counter UAVs
Cazzato, Dario; Cimarelli, Claudio UL; Voos, Holger UL

in 15th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications - Volume 5: VISAPP, Valletta 27-29 February 2020 (2020, February 27)

Two typical Unmanned Aerial Vehicles (UAV) countermeasures involve the detection and tracking of the UAV position, as well as of the human pilot; they are of critical importance before taking any ... [more ▼]

Two typical Unmanned Aerial Vehicles (UAV) countermeasures involve the detection and tracking of the UAV position, as well as of the human pilot; they are of critical importance before taking any countermeasure, and they already obtained strong attention from national security agencies in different countries. Recent advances in computer vision and artificial intelligence are already proposing many visual detection systems from an operating UAV, but they do not focus on the problem of the detection of the pilot of another approaching unauthorized UAV. In this work, a first attempt of proposing a full autonomous pipeline to process images from a flying UAV to detect the pilot of an unauthorized UAV entering a no-fly zone is introduced. A challenging video sequence has been created flying with a UAV in an urban scenario and it has been used for this preliminary evaluation. Experiments show very encouraging results in terms of recognition, and a complete dataset to evaluate artificial intelligence-based solution will be prepared. [less ▲]

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See detailPrivacy and Security of Big Data in AI Systems:A Research and Standards Perspective
Esmaeilzadeh Dilmaghani, Saharnaz UL; Brust, Matthias R. UL; Danoy, Grégoire UL et al

in 2019 IEEE International Conference on Big Data (Big Data), 9-12 December 2019 (2020, February 24)

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See detailPreventing Overloading Incidents on Smart Grids: A Multiobjective Combinatorial Optimization Approach
Antoniadis, Nikolaos UL; Cordy, Maxime UL; Sifaleras, Angelo et al

in Communications in Computer and Information Science (2020, February 15)

Cable overloading is one of the most critical disturbances that may occur in smart grids, as it can cause damage to the distribution power lines. Therefore, the circuits are protected by fuses so that ... [more ▼]

Cable overloading is one of the most critical disturbances that may occur in smart grids, as it can cause damage to the distribution power lines. Therefore, the circuits are protected by fuses so that, the overload could trip the fuse, opening the circuit, and stopping the flow and heating. However, sustained overloads, even if they are below the safety limits, could also damage the wires. To prevent overload, smart grid operators can switch the fuses on or off to protect the circuits, or remotely curtail the over-producing/over-consuming users. Nevertheless, making the most appropriate decision is a daunting decision-making task, notably due to contractual and technical obligations. In this paper, we define and formulate the overloading prevention problem as a Multiobjective Mixed Integer Quadratically Constrained Program. We also suggest a solution method using a combinatorial optimization approach with a state-of-the-art exact solver. We evaluate this approach for this real-world problem together with Creos Luxembourg S.A., the leading grid operator in Luxembourg, and show that our method can suggest optimal countermeasures to operators facing potential overloading incidents. [less ▲]

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See detailVon Imaginationen himmlischer Erlösung bis zum Pogrom – Der Umgang mit Leprakranken im historischen Überblick.
Uhrmacher, Martin UL

Scientific Conference (2020, February 13)

Die Geschichte der Lepra ist geprägt von Elend, Siechtum und Ausgrenzung bis hin zum Pogrom, aber andererseits auch von religiöser Überhöhung, Privilegierung und beispielhafter Fürsorge. Diese Ambivalenz ... [more ▼]

Die Geschichte der Lepra ist geprägt von Elend, Siechtum und Ausgrenzung bis hin zum Pogrom, aber andererseits auch von religiöser Überhöhung, Privilegierung und beispielhafter Fürsorge. Diese Ambivalenz ist sehr typisch für den Umgang mit Leprakranken, auch Leprose genannt, im Mittelalter und in der frühen Neuzeit. Und sie spiegelt sich auch in Vorurteilen wider, mit denen die an Lepra Erkrankten konfrontiert waren. Das Spektrum reicht hier von Imaginationen himmlischer Erlösung bis hin zur Unterstellung von Sünden und Verbrechen. Der Vortrag beschreibt zunächst Ursprünge und Ausprägungen von Vorurteilen gegenüber Leprakranken beschreiben. Kann man überhaupt von „den Leprosen“ sprechen, die stets als typische Randgruppe der mittelalterlichen Gesellschaft bezeichnet werden? Oder führten Vorurteile in unterschiedlichen zeitlichen und sozialen Kontexten womöglich zur Bildung verschiedener Gruppen? Hierzu werden im zweiten Teil ausgewählte Quellenbeispiele in den Blick genommen. Sie zeigen auf, welche konkreten Auswirkungen bestehende Vorurteile in der Praxis auf die Lebenswelt von Leprakranken hatten. Und sie ermöglichen, der Wandlung von Vorurteilsstrukturen in der long durée nachzugehen. [less ▲]

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See detailMobile App to SGX Enclave Secure Channel
Carvalho Ota, Fernando Kaway UL; Meira, Jorge Augusto UL; Cassagnes, Cyril UL et al

in 2019 IEEE International Symposium on Software Reliability Engineering Workshops (2020, February 13)

The current challenge for several applications is to guarantee the user’s privacy when using personal data. The broader problem is to transfer and process the data without exposing the sensitive content ... [more ▼]

The current challenge for several applications is to guarantee the user’s privacy when using personal data. The broader problem is to transfer and process the data without exposing the sensitive content to anyone, including the service provider(s). In this paper, we address this challenge by proposing a protocol to combine secure frameworks in order to exchange and process sensitive data, i.e. respecting user’s privacy. Our contribution is a protocol to perform a secure exchange of data between a mobile application and a trusted execution environment. In our experiments we show independent implementations of our protocol using three different encryption modes (i.e., CBC, ECB, GCM encryption). Our results support the feasibility and importance of an end-to-end secure channel protocol. [less ▲]

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See detailNew opportunities by laser joining of dissimilar materials
Plapper, Peter UL

Scientific Conference (2020, February 13)

The presentation gives an overview about research projects at UL related to laser welding of dissimilar materials. Literature reference at the end enables the reader to dig deeper in case some specific ... [more ▼]

The presentation gives an overview about research projects at UL related to laser welding of dissimilar materials. Literature reference at the end enables the reader to dig deeper in case some specific projects are of interest. [less ▲]

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See detailPIAF : développer la Pensée Informatique et Algorithmique dans l'enseignement Fondamental
Busana, Gilbert UL; Denis, Brigitte; Duflot-Kremer, Marie et al

Poster (2020, February 06)

Dans cet article, nous présentons les objectifs et premières réalisations du projet PIAF soutenu par l’Union Européenne et visant à développer l’apprentissage de la pensée informatique et algorithmique ... [more ▼]

Dans cet article, nous présentons les objectifs et premières réalisations du projet PIAF soutenu par l’Union Européenne et visant à développer l’apprentissage de la pensée informatique et algorithmique dans l’enseignement fondamental. Ce projet rassemble des chercheur·e·s en sciences de l’éducation et en informatique, provenant de quatre pays (Allemagne, Belgique, France et Luxembourg), autour du thème de la formation des enseignant·e·s. Plus concrètement, il s’agit de définir un cadre (référentiel de compétences, scénarios pédagogiques) permettant aux enseignant·e·s de (i) s’approprier le concept de pensée informatique et algorithmique et de (ii) mettre en œuvre des activités d’apprentissage favorisant le développement de cette pensée chez l’enfant. [less ▲]

Detailed reference viewed: 70 (4 UL)