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See detailA Forcing Fictitious Domain Method to Simulate Fluid-particle Interaction of Particles with Super-quadric Shape
Wu, Mingqiu UL; Peters, Bernhard UL; Rosemann, Tony et al

in Powder Technology (2019), Accepted, in press

In this work, we develop a new framework to directly simulate super-quadric (SQ) particles in fluid flows based on a forcing fictitious domain method. Specifically, a super-quadric particle function is ... [more ▼]

In this work, we develop a new framework to directly simulate super-quadric (SQ) particles in fluid flows based on a forcing fictitious domain method. Specifically, a super-quadric particle function is used to represent the particle shape of different types in a flexible manner. The immersion of particles in the fluid is handled by imposing rigid solid body motion in the particle domain, as well as adding a local forcing term to the Navier-Stokes equations by calculating the integral of both the pressure gradient and the particle velocity over the whole particle domain. Particle shapes are varied by changing the five super-quadric parameters of the SQ equation. We validate our approach by performing simulations of flow around a fixed particle and sedimentation of a particle in a channel in 2D and 3D. The validation results indicate that the current simulation results show a good agreement with experimental data. Moreover, our method is used to study the flow around fixed non-spherical particles with different orientations and particle Reynolds numbers. The particle Reynolds numbers vary from 0.1 to 3000. The super-quadric particles exemplarily considered in the current study are an ellipsoidal particle and fibre-like particles. We present the results for drag and lift coefficients at different particle orientations and different particle Reynolds numbers. The obtained results lay the foundation to apply the framework to flown through multi-particle systems in the near future. [less ▲]

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See detailUser Experience Design for E-Voting: How mental models align with security mechanisms
Zollinger, Marie-Laure UL; Distler, Verena UL; Roenne, Peter UL et al

in Electronic Voting (2019, October)

This paper presents a mobile application for vote-casting and vote-verification based on the Selene e-voting protocol and explains how it was developed and implemented using the User Experience Design ... [more ▼]

This paper presents a mobile application for vote-casting and vote-verification based on the Selene e-voting protocol and explains how it was developed and implemented using the User Experience Design process. The resulting interface was tested with 38 participants, and user experience data was collected via questionnaires and semi-structured interviews on user experience and perceived security. Results concerning the impact of displaying security mechanisms on UX were presented in a complementary paper. Here we expand on this analysis by studying the mental models revealed during the interviews and compare them with theoretical security notions. Finally, we propose a list of improvements for designs of future voting protocols. [less ▲]

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See detailOpinion Statement ECJ-TF 2/2019 on the ECJ Decisions of 26 February 2019 inN Luxembourg I et al.(Joined Cases C-115/16, C-118/16, C-119/16 and C-299/16) andT Danmark et al.(Joined Cases C-116/16 and C-117/17)
García Prats, Alfredo; Haslehner, Werner UL; Heydt, Volker et al

in European Taxation (2019), 59(10), 10

The article acknowledges that the “Danish beneficial ownership cases” address a number of important and timely issues, especially with regard to the concept of abuse in EU law. These include (i) the ... [more ▼]

The article acknowledges that the “Danish beneficial ownership cases” address a number of important and timely issues, especially with regard to the concept of abuse in EU law. These include (i) the expansion of the general anti-abuse principle enshrined in EU law to areas of tax law that are subject to minimal harmonization, (ii) the use of the OECD materials to define the beneficial ownership concept, (iii) the conflation of the beneficial ownership concept with the general anti-abuse principle and the Court’s attempt to give the notion of “abuse” workable contours, and (iv) the reading of an effective subject-to-tax clause with regard to interest income into the definition of a “company” laid down in the IRD. The article also, however, predicts that domestic courts will struggle to translate the abstract guidance of the “Danish beneficial ownership cases” into concrete decisions, that practitioners and academics alike will have to discuss building blocks and nuances of the Grand Chamber’s decisions for some time to come, and that consideration needs to be given to the impact these cases will have on current tax structures. [less ▲]

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See detailP3LS : Plausible Deniability for Practical Privacy-Preserving Live Streaming
Decouchant, Jérémie UL; Boutet, Antoine; Yu, Jiangshan et al

Scientific Conference (2019, October)

Video consumption is one of the most popular Internet activities worldwide. The emergence of sharing videos directly recorded with smartphones raises important privacy concerns. In this paper we propose ... [more ▼]

Video consumption is one of the most popular Internet activities worldwide. The emergence of sharing videos directly recorded with smartphones raises important privacy concerns. In this paper we propose P3LS , the first practical privacy-preserving peer-to-peer live streaming system. To protect the privacy of its users, P3LS relies on k-anonymity when users subscribe to streams, and on plausible deniability for the dissemination of video streams. Specifically, plausible deniability during the dissemination phase ensures that an adversary is never able to distinguish a user’s stream of interest from the fake streams from a statistical analysis (i.e., using an analysis of variance). We exhaustively evaluate P3LS and show that adversaries are not able to identify the real stream of a user with very high confidence. Moreover, P3LS consumes 30% less bandwidth than the standard k-anonymity approach where nodes fully contribute to the dissemination of k streams. [less ▲]

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See detailEvent Notification in CAN-based Sensor Networks
Bloom, Gedare; Cena, Gianluca; Cibrario Bertolotti, Ivan et al

in IEEE Transactions on Industrial Informatics (2019), 15(10), 5613-5625

Preventive and reactive maintenance require the collection of an ever-increasing amount of information from industrial plants and other complex systems, like those based on robotized cells, a need that ... [more ▼]

Preventive and reactive maintenance require the collection of an ever-increasing amount of information from industrial plants and other complex systems, like those based on robotized cells, a need that can be fulfilled by means of a suitable event notification mechanism. At the same time, timing and delivery reliability requirements in those scenarios are typically less demanding than in other cases, thus enabling the adoption of best-effort notification approaches. This paper presents, evaluates, and compares some of those approaches, based on either standard CAN messaging or a recently proposed protocol extension called CAN XR. In the second case, the combined use of Bloom filters is also envisaged to increase flexibility. Results show that the latter approaches are advantageous in a range of event generation rates and network topologies of practical relevance. [less ▲]

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See detailEFFECTS OF MULTIPLE OSCILLATOR PHASE NOISE IN PRECODING PERFORMANCE
Martinez Marrero, Liz UL

Scientific Conference (2019, October)

Satellite Precoding is a promising technique to meet the target data rates of the future high throughput satellite systems and the costs per bit as required by 5G applications and networks, but it ... [more ▼]

Satellite Precoding is a promising technique to meet the target data rates of the future high throughput satellite systems and the costs per bit as required by 5G applications and networks, but it requires strict synchronization among the transmitted waveforms, in addition to accurate channel state information. Most of the published work about this topic consider ideal oscillators, but in practice, the output of an oscillator is not a single spectral line at the nominal frequency. This paper proposes a model for the oscillator phase noise and analyzes the resulting received signal to interference plus noise ratio (SNIR) in a satellite communication system using Precoding. Simulations of a communication satellite system with a two-beam transponder and two receivers were performed to compute the effective SNIR. This work uses a simulator which also considers practical impairments such as time misalignment, errors in the channel state information, interference, thermal noise and phase noise masks for satellite oscillators. The Precoding methods used for the analysis are Zero Forcing (ZF) and Minimum Mean Square Error (MMSE). The obtained results prove that there is a degradation in the performance due to the use of independent oscillators but this effect is compensated by the precoding matrix. [less ▲]

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See detailA mechanical design model for steel and concrete composite members with web openings
Claßen, Martin; Kurz, Wolfgang; Schäfer, Markus UL et al

in Engineering Structures (2019), Engineering Structures 197:109417(109417),

In web opening regions, a significant share of the global shear force is redistributed from the perforated web of the steel beam to the reinforced concrete (RC) slab. This redistribution leads to vertical ... [more ▼]

In web opening regions, a significant share of the global shear force is redistributed from the perforated web of the steel beam to the reinforced concrete (RC) slab. This redistribution leads to vertical forces in the shear connectors close to both edges of the opening and influences the internal forces in the steel beam and the RC slab over a length of approximately three times the opening length a0. The global shear failure in the web opening region is affected by the rather brittle behavior of the concrete and is either characterized by a diagonal shear cracking failure of the RC slab, or a local bending failure at the opening edges, or vertical connector failure (concrete break-out) at the ends of the opening. This paper is intended to clarify the structural behavior of web opening regions and proposes easy-to-use models that make it possible to analyze the local internal forces of each partial beam in a mechanically consistent manner. Based on these models, a novel design procedure is presented, that allows efficient design and dimensioning of web openings as well as prediction of shear resistance and failure mode. [less ▲]

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See detailDie ‚Circular Economy‘ als Ausweg aus der Wachstumsfalle? Diskussionsbeitrag
Schulz, Christian UL

in Reckinger, Carole; Urbé, Robert (Eds.) Sozialalmanach 2019. Schwéierpunkt: Qualitativen Wuesstem (2019)

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See detailQualitatives Wachstum in Stadt und Land? Elefant im Raum und zugleich leerer Signifikant
Becker, Tom UL; Hesse, Markus UL; Schulz, Christian UL

in Reckinger, Carole; Urbé, Robert (Eds.) Sozialalmanach 2019. Schwéierpunkt: Qualitativen Wuesstem (2019)

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See detailSimultaneous State and False-Data Injection Attacks Reconstruction for NonLinear Systems: an LPV Approach
Bezzaoucha, Souad UL; Voos, Holger UL

in Bezzaoucha, Souad (Ed.) International Conference on Automation, Control and Robots (2019, October)

The present contribution addresses simultaneous state and actuator/sensor false-data injection attacks reconstruction for nonlinear systems. The considered actuator/sensor attacks are modeled as time ... [more ▼]

The present contribution addresses simultaneous state and actuator/sensor false-data injection attacks reconstruction for nonlinear systems. The considered actuator/sensor attacks are modeled as time-varying parameters with a multiplicative effect on the actuator input signal and the sensor output signal, respectively. Based on the sector non-linearity approach and the convex polytopic transformation, the nonlinear model is written in a Linear Parameter-Varying (LPV) form, then an observer allowing both state and attack reconstruction is designed by solving an LMI optimization problem. [less ▲]

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See detailOn the Event-based Attack-tolerant Control: A Polytopic Representation
Bezzaoucha, Souad UL; Voos, Holger UL

in Bezzaoucha, Souad (Ed.) International Conference on Automation, Control and Robots (2019, October)

In the present contribution, we present a new event-based control representation. Based on the polytopic approach, more specifically the sector nonlinear transformation, an event-based attack-tolerant ... [more ▼]

In the present contribution, we present a new event-based control representation. Based on the polytopic approach, more specifically the sector nonlinear transformation, an event-based attack-tolerant control, and scheduling co-design strategy are proposed. From the event triggering definition (sample-and-hold strategy), polytopic writing of the event-triggered feedback control is first presented and then incorporated into the system dynamics for analysis. Our goal is to present a unique model that is able to deal with the co-design problem simultaneously and that can be handled by classical control synthesis tools. The novel representation, including data deception and attack tolerant control is formulated as a BMI optimization problem ensuring both stability and some level performance requirements (L2 attenuation of the cyber-attack). [less ▲]

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See detailSDN-based Pseudonym-Changing Strategy for Privacy Preservation in Vehicular Networks
Boualouache, Abdelwahab UL; Soua, Ridha UL; Engel, Thomas UL

in 15th International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob'19) (2019, October)

The pseudonym-changing approach is the de-factolocation privacy solution proposed by security standards toensure that drivers are not tracked during their journey. SeveralPseudonym Changing Strategies ... [more ▼]

The pseudonym-changing approach is the de-factolocation privacy solution proposed by security standards toensure that drivers are not tracked during their journey. SeveralPseudonym Changing Strategies (PCSs) have been proposed tosynchronize Pseudonym Changing Processes (PCPs) between con-nected vehicles. However, most of the existing strategies are static,rigid and do not adapt to the vehicles’ context. In this paper, weexploit the Software Defined Network (SDN) paradigm to proposea context-aware pseudonym changing strategy (SDN-PCS) whereSDN controllers orchestrate the dynamic update of the securityparameters of the PCS. Simulation results demonstrate that SDN-PCS strategy outperforms typical static PCSs to perform efficientPCPs and protect the location privacy of vehicular network users [less ▲]

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See detailBericht über die "Demenzforschungstage" 2019. Einbezug von Betroffenen in die Forschung zu kognitivem Altern und Demenz
Leist, Anja UL

Report (2019)

On 19 and 20 September 2019, the first "Dementia Research Days" took place on the Belval campus of the University of Luxembourg. People living with dementia were invited to the university to discuss the ... [more ▼]

On 19 and 20 September 2019, the first "Dementia Research Days" took place on the Belval campus of the University of Luxembourg. People living with dementia were invited to the university to discuss the research questions of the ERC-CRISP project and to advise the researchers on the dissemination of the research results. The idea of giving people affected by dementia a voice in research projects is already being successfully implemented in other countries such as the UK. The report presents some information on the research project for the general public. After that, the contributions of the participants are summarised. [less ▲]

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See detailThree models of flexible talent management
Usanova, Ksenia; Geraudel, Mickaël UL; D'Armagnac, Sophie et al

Scientific Conference (2019, September 30)

Detailed reference viewed: 27 (1 UL)
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See detailHow To Attract And Retain Talents In Not-For-Profit Organizations?
Usanova, Ksenia; Telitsina, Aleksandra; Geraudel, Mickaël UL

Scientific Conference (2019, September 30)

Detailed reference viewed: 23 (0 UL)
See detailParadigmenwechsel in der Lehrerausbild
Baumann, Isabell UL; Harion, Dominic UL

Article for general public (2019)

Detailed reference viewed: 25 (0 UL)
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See detailQualitative interviewing in multilingual research
Kalocsanyiova, Erika UL; Shatnawi, Malika

Scientific Conference (2019, September 27)

A growing body of research in super-diverse societies is conducted, by necessity, in multiple languages. Multilingual research practices can play a fundamental role in empowering participants and ... [more ▼]

A growing body of research in super-diverse societies is conducted, by necessity, in multiple languages. Multilingual research practices can play a fundamental role in empowering participants and privileging their voices, especially in migration-related studies. Yet, questions of cross-language interviewing are for the most part avoided or ignored in mainstream research. This contribution seeks to bring cross-language communication back into the focus of methodological discussions. Our paper builds on multilingual interview material extracted from a two-year linguistic ethnographic research project on forced migrants’ integration trajectories in Luxembourg. It looks at interpreter-mediated research encounters, as well as interviewees’ translation and translanguaging moves. Audio recordings and field notes from collaborative data analysis sessions underpin the data for this contribution. Our examples show that there is merit in fixing our analytical gaze on the minute details of language use across different codes, as these allow for a novel inquiry into specific moments of meaning making, role performances and rapport-building in qualitative interviewing. [less ▲]

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See detailNoCry: No More Secure Encryption Keys for Cryptographic Ransomware
Genç, Ziya Alper UL; Lenzini, Gabriele UL; Ryan, Peter UL

in 2nd International Workshop on Emerging Technologies for Authorization and Authentication (2019, September 27)

Since the appearance of ransomware in the cyber crime scene, researchers and anti-malware companies have been offering solutions to mitigate the threat. Anti-malware solutions differ on the specific ... [more ▼]

Since the appearance of ransomware in the cyber crime scene, researchers and anti-malware companies have been offering solutions to mitigate the threat. Anti-malware solutions differ on the specific strategy they implement, and all have pros and cons. However, three requirements concern them all: their implementation must be secure, be effective, and be efficient. Recently, Genç et al. proposed to stop a specific class of ransomware, the cryptographically strong one, by blocking unauthorized calls to cryptographically secure pseudo-random number generators, which are required to build strong encryption keys. Here, in adherence to the requirements, we discuss an implementation of that solution that is more secure (with components that are not vulnerable to known attacks), more effective (with less false negatives in the class of ransomware addressed) and more efficient (with minimal false positive rate and negligible overhead) than the original, bringing its security and technological readiness to a higher level. [less ▲]

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See detailThe impact of resilience on perceived chronic stress in undergraduate psychology students
Lenz, Hannah; Steffgen, Georges UL

Poster (2019, September 26)

The purpose of this exploratory study was to analyze the relationship between academic stressors and chronic stress in undergraduate psychology students, and to identify whether resilience and/or social ... [more ▼]

The purpose of this exploratory study was to analyze the relationship between academic stressors and chronic stress in undergraduate psychology students, and to identify whether resilience and/or social support function as mediators amid this relationship. Students from the University of Luxembourg and the University of Trier (N = 152) were recruited to fill out an online questionnaire consisting of the Trier inventory of chronic stress (Schulz et al., 2004), the resilience scale (Leppert et al., 2008), the perceived social support scale (Kliem et al., 2015), and five dimensions of academic stressors (Herbst et al., 2016). Results show a positive correlation between academic stressors and chronic stress. Multiple regression analysis prove that neither gender, home university, additional occupation nor social support are significant predictors of chronic stress. Compared to academic stressors and resilience, which account for more than 56% of the variance of students’ experienced chronic stress. Furthermore, academic stressors and chronic stress are mediated by resilience but not by perceived social support. The implications of the findings are discussed in terms of their relevance for the development of intervention programs against chronic stress of undergraduate students. [less ▲]

Detailed reference viewed: 35 (2 UL)