References of "Scientific congresses, symposiums and conference proceedings"
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See detailLuxembourg Completing its Space Legislation
Hofmann, Mahulena UL

in Hofmann, Mahulena (Ed.) Luxembourg Completing its Space Legislation (2022, September)

On January 2021, the general Space Law of Luxembourg entered into force. It complemented the 2017 Law on Space Resources by an authorization regime applicable to the remaining space activities under ... [more ▼]

On January 2021, the general Space Law of Luxembourg entered into force. It complemented the 2017 Law on Space Resources by an authorization regime applicable to the remaining space activities under Luxembourg's jurisdiction. By these steps, the Luxembourg authorities have now at their disposal a full-coverage legal framework capable to authorize all space activities. [less ▲]

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See detailSpace-as-a-Service: A Framework and Taxonomy of -as-a-Service Concepts for Space
Hein, Andreas UL; Bruce Rosete, Citlali UL

in Proceedings of the International Astronautical Congress 2022 (2022, September)

The servitization of space is introducing profound change, challenging established companies with new business models, and significantly lowering the entry barrier to space. New types of services such as ... [more ▼]

The servitization of space is introducing profound change, challenging established companies with new business models, and significantly lowering the entry barrier to space. New types of services such as Mission-as-a-Service, Satellite-as-a-Service, Constellation-as-a-Service, etc., are introduced. However, what these notions mean is not clear and in practice, they are often used with contradicting meanings. This paper aims to provide an initial survey of various new service concepts in the space domain and develops a taxonomy and framework for classifying these emerging services with their underlying systems. A particular emphasis is put on distinguishing novel, "New Space" services from traditional space services. We find that these new space services differ, compared to traditional space services in at least three aspects: New space services have their origin in a transition from a product-to a use-oriented business model and make reference to Cloud computing and its underlying techniques such as virtualization. We conclude that analogous to the terrestrial impact of Cloud computing on the emergence of numerous e-commerce start-ups, we might see a similar surge of in-space applications, building on a new space service backbone. Such a development is likely going to be enabled by the shift from traditionally high capital expenditures of developing space applications to operating expenses, thereby lowering the entry barrier. [less ▲]

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See detailLearning to Optimize: Balancing Two Conflict Metrics in MB-HTS Networks
Bui, Van-Phuc; Chien, Trinh-Van; Lagunas, Eva UL et al

in Advanced Satellite Multimedia Conference / Signal Processing for Space Communications Workshop (ASMS), Gratz, Viena, Sept. 2022 (2022, September)

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See detailObfuscating LLVM Intermediate Representation Source Code with NSGA-II
de la Torre, Juan Carlos; Aragó-Jurado, José Miguel; Jareño, Javier et al

in 15th Intl. Conf. on Computational Intelligence in Security for Information Systems (CISIS'22) (2022, September)

With the generalisation of distributed computing paradigms to sustain the surging demands for massive processing and data-analytic capabilities, the protection of the intellectual property tied to the ... [more ▼]

With the generalisation of distributed computing paradigms to sustain the surging demands for massive processing and data-analytic capabilities, the protection of the intellectual property tied to the executed programs transferred onto these remote shared platforms becomes critical. A more and more popular solution to this problem consists in applying obfuscating techniques, in particular at the source code level. Informally, the goal of obfuscation is to conceal the purpose of a program or its logic without altering its functionality, thus preventing reverse-engineering on the program even with the help of computing resources. This allows to protect software against plagiarism, tampering, or finding vulnerabilities that could be used for different kinds of attacks. The many advantages of code obfuscation, together with its low cost, makes it a popular technique. This paper proposes a novel methodology for source code obfuscation relying on the reference LLVM compiler infrastructure that can be used together with other traditional obfuscation techniques, making the code more robust against reverse engineering attacks. The problem is defined as a Multi-Objective Combinatorial Optimization (MOCO) problem, where the goal is to find sequences of LLVM optimizations that lead to highly obfuscated versions of the original code. These transformations are applied to the back-end pseudo- assembly code (i.e., LLVM Intermediate Representation), thus avoiding any further optimizations by the compiler. Three different problem flavours are defined and solved with popular NSGA-II genetic algorithm. The promising results show the potential of the proposed technique. [less ▲]

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See detailThe Prosody of Cheering in Sport Events
Zygis, Marzena; Wesolek, Sarah; Hosseini Kivanani, Nina UL et al

in Proc. Interspeech 2022 (2022, September)

Motivational speaking usually conveys a highly emotional message and its purpose is to invite action. The goal of this paper is to investigate the prosodic realization of one particular type of cheering ... [more ▼]

Motivational speaking usually conveys a highly emotional message and its purpose is to invite action. The goal of this paper is to investigate the prosodic realization of one particular type of cheering, namely inciting cheering for single addressees in sport events (here, long-distance running), using the name of that person. 31 native speakers of German took part in the experiment. They were asked to cheer up an individual marathon runner in a sporting event represented by video by producing his or her name (1-5 syllables long). For reasons of comparison, the participants also produced the same names in isolation and carrier sentences. Our results reveal that speakers use different strategies to meet their motivational communicative goals: while some speakers produced the runners’ names by dividing them into syllables, others pronounced the names as quickly as possible putting more emphasis on the first syllable. A few speakers followed a mixed strategy. Contrary to our expectations, it was not the intensity that mostly contributes to the differences between the different speaking styles (cheering vs. neutral), at least in the methods we were using. Rather, participants employed higher fundamental frequency and longer duration when cheering for marathon runners. [less ▲]

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See detailJoint Beam Placement and Load Balancing Optimization for Non-Geostationary Satellite Systems
Bui, Van-Phuc; Chien, Trinh-Van; Lagunas, Eva UL et al

in IEEE International Mediterranean Conference on Communications and Networking (IEEE MediCom), Athens, Greece, Sept. 2022 (2022, September)

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See detailReinforcement Learning for Attitude Control of a Spacecraft with Flexible Appendages
Mahfouz, Ahmed UL; Valiullin, Ayrat; Lukashevichus, Alexey et al

in IAC 2022 congress proceedings, 73rd International Astronautical Congress (IAC) (2022, September)

This study explores the reinforcement learning (RL) approach to constructing attitude control strategies for a LEOsatellite with flexible appendages. Attitude control system actuated by a set of three ... [more ▼]

This study explores the reinforcement learning (RL) approach to constructing attitude control strategies for a LEOsatellite with flexible appendages. Attitude control system actuated by a set of three reaction wheels is considered.The satellite is assumed to move in a circular low Earth orbit under the action of gravity-gradient torque, randomdisturbance torque, and oscillations excited in flexible appendages. The control policy for rest-to-rest slew maneuversis learned via the Proximal Policy Optimization (PPO) technique. The robustness of the obtained control policy isanalyzed and compared to that of conventional controllers. The first part of the study is focused on problem formulationin terms of Markov Decision Processes, analysis of different reward-shaping techniques, and finally training the RL-agent and comparing the obtained results with the state-of-the-art RL-controllers as well as with the performance ofa commonly used quaternion feedback regulator (Lyapunov-based PD controller). We then proceed to consider thesame spacecraft with flexible appendages added to its structure. Equations of excitable oscillations are appended tothe system and coupling terms are added describing the interactions between the main rigid body and the flexiblestructures. The dynamics of the rigid spacecraft thus becomes coupled with that of its flexible appendages and thecontrol strategy should change accordingly in order to prevent actions that entail excitation of oscillation modes.Again PPO is used to learn the control policy for rest-to-rest slew maneuvers in the extended system. All in all,the proposed reinforcement learning strategy is shown to converge to a policy that matches the performance of thequaternion feedback regulator for a rigid spacecraft. It is also shown that a policy can be trained to take into accountthe highly nonlinear dynamics caused by the presence of flexible elements that need to be brought to rest in the requiredattitude. We also discuss the advantages of the reinforcement learning approach such as robustness and ability of onlinelearning pertaining to the systems that require a high level of autonomy [less ▲]

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See detail5G-NTN GEO-based In-Lab Demonstrator using OpenAirInterface5G
Kumar, Sumit UL; Abdalla, Abdelrahman UL; Kodheli, Oltjon UL et al

in 11th Advanced Satellite Multimedia Conference (2022, September)

The integration of 5G with Non-Terrestrial Network (NTN) components is going through a series of technological advancements and soon satellites will be a part of the 5G ecosystem. Early demonstrators ... [more ▼]

The integration of 5G with Non-Terrestrial Network (NTN) components is going through a series of technological advancements and soon satellites will be a part of the 5G ecosystem. Early demonstrators, especially based on open-source implementations, are essential to support further research. In this work, we discuss the ongoing activities and developments related to the project 5G-Enabled Ground Segment Technologies OverThe-Air Demonstrator (5G-GoA) which has been funded under the ESA-ARTES program. The vision of 5G-GoA is developing and implementing suitable modifications in the 5G New Radio (NR) standard for enabling direct radio access to 5G services using a transparent GEO satellite. For this purpose, we have used OpenAirInterface(OAI) which is a Software Defined Radio (SDR) based open-source implementation of the 5G-NR protocol stack. We adapted it to address the challenges caused by the excessive round-trip delay in GEO satellites. Our solutions encompass all the layers of the 5G protocol stack: The physical layer (e.g. synchronization) up to upper layer implementations (e.g. timers and random-access procedure) of the Radio Access Network. Our modifications comply with the specifications mentioned for 5GNTN in the recently frozen 3GPP Release-17. An end-to-end demonstrator has been developed for in-lab validation over a satellite channel emulator prior to over-the-satellite testing. Our initial experiments show promising results and the feasibility of direct access to 5G services through transparent GEO satellites. [less ▲]

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See detailUpdate: Besteuerung der digitalen Wirtschaft (International und Europäische Union)
Sinnig, Julia UL

in Taeger, Jürgen (Ed.) Tagungsband 2022: Daten, Plattformen und KI als Dreiklang unserer Zeit (2022, September)

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See detailPose Estimation of a Known Texture-Less Space Target using Convolutional Neural Networks
Rathinam, Arunkumar UL; Gaudilliere, Vincent UL; Pauly, Leo UL et al

in 73rd International Astronautical Congress, Paris 18-22 September 2022 (2022, September)

Orbital debris removal and On-orbit Servicing, Assembly and Manufacturing [OSAM] are the main areas for future robotic space missions. To achieve intelligence and autonomy in these missions and to carry ... [more ▼]

Orbital debris removal and On-orbit Servicing, Assembly and Manufacturing [OSAM] are the main areas for future robotic space missions. To achieve intelligence and autonomy in these missions and to carry out robot operations, it is essential to have autonomous guidance and navigation, especially vision-based navigation. With recent advances in machine learning, the state-of-the-art Deep Learning [DL] approaches for object detection, and camera pose estimation have advanced to be on par with classical approaches and can be used for target pose estimation during relative navigation scenarios. The state-of-the-art DL-based spacecraft pose estimation approaches are suitable for any known target with significant surface textures. However, it is less applicable in a scenario where the target is a texture-less and symmetric object like rocket nozzles. This paper investigates a novel ellipsoid-based approach combined with convolutional neural networks for texture-less space object pose estimation. Also, this paper presents the dataset for a new texture-less space target, an apogee kick motor, which is used for the study. It includes the synthetic images generated from the simulator developed for rendering synthetic space imagery. [less ▲]

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See detailIndicators for assessing the necessity of power system flexibility: a systematic review and literature meta-analysis
Bhuiyan, Rajon UL; Weissflog, Jan; Schoepf, Michael UL et al

in Proceedings of the 18th International Conference on the European Energy Market (EEM) (2022, September)

There are different flexibility options to align power systems to volatile feed-in of renewable electricity sources. The flexibility options differ in the dimensions of time, spatiality, and resource type ... [more ▼]

There are different flexibility options to align power systems to volatile feed-in of renewable electricity sources. The flexibility options differ in the dimensions of time, spatiality, and resource type. To make policy decisions on future energy systems, it is necessary to get a top-down indication of how much power system flexibility is needed. With the ongoing energy transition, there is yet no comprehensive overview of indicators that describe which dimension of flexibility will be necessary to what extent for different energy systems. Therefore, this paper provides a first overview of indicators that can be used to assess the necessity of power system flexibility. Thus, we do a systematic literature review to identify indicators that allow us to estimate the necessity of power system flexibility. We conduct a meta-analysis of these indicators and categorize them as indicators that either stand for an increasing or decreasing necessity of power system flexibility. Our paper can help inform policy, assess needed changes to system operations, increase stakeholder acceptance and investor confidence in implementing new technology and measures. [less ▲]

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See detailSatellite Beam Densification for High-Demand Areas
Jubba Honnaiah, Puneeth UL; Lagunas, Eva UL; Chatzinotas, Symeon UL et al

in 2022 11th Advanced Satellite Multimedia Systems Conference and the 17th Signal Processing for Space Communications Workshop (ASMS/SPSC) (2022, September)

Conventional multi-beam pattern design in Geostationary (GEO) satellite communication systems consists of a regular grid of non-reconfigurable beams, where the beams overlap is typically assumed at the ... [more ▼]

Conventional multi-beam pattern design in Geostationary (GEO) satellite communication systems consists of a regular grid of non-reconfigurable beams, where the beams overlap is typically assumed at the point where the beam edge reaches a 3-dB loss in the antenna pattern (with respect to the beam center). For certain high demand areas, this 3dB loss has a significant impact. To overcome this issue, in this paper we evaluate the potential gain of beam densification, i.e. considering an increased number of beams (keeping the same beam size and shape) to cover hot-spot areas, with the aim to push the beam overlap and increase the beam gain. In particular, we compare two beam patterns (kindly provided by ESA): One with regular beam grid, and one with densification in a particular hot-spot area. We provide a comparison in terms of per-beam average SINR and capacity, as well as an overall system analysis considering the whole densified region. [less ▲]

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See detailAn Overview of Channel Models for NGSO Satellites
Monzon Baeza, Victor UL; Lagunas, Eva UL; Al-Hraishawi, Hayder UL et al

Scientific Conference (2022, September)

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See detailDeontic Sentence Classification Using Tree Kernel Classifiers
Liga, Davide UL; Palmirani, Monica

in Intelligent Systems and Applications (2022, August 31)

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See detailNumerical Investigation of Steel-LVL Timber Composite Beams
Romero, Alfredo UL; Yang, Jie UL; Hanus, François et al

in ce/papers (2022, August 31)

In the last years, new connectors of steel-concrete composite flooring systems have been developed and investigated to enhance the circularity and standardisation of building components. Recent studies ... [more ▼]

In the last years, new connectors of steel-concrete composite flooring systems have been developed and investigated to enhance the circularity and standardisation of building components. Recent studies showed that timber can be used as an alternative to the concrete slab in hybrid structures. However, the knowledge in steel-timber composite flooring systems is still very limited. This contribution presents numerical investigations of steel-LVL timber composite beams. The load deformation behaviour was determined through 3D finite element models. The design resistance of the composite beams was estimated analytically through a strain-controlled approach. The results of this study show that the resistances obtained in the numerical models and the strain-controlled approach are in good agreement. Moreover, obtained deflections and slip values were given at ultimate load. [less ▲]

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See detailA Reusable Structural System Fit for Geometrical Standardisation and Serial Production
Odenbreit, Christoph UL; Yang, Jie UL; Romero, Alfredo UL et al

in ce/papers (2022, August 31)

A series of demountable connections for reusable composite flooring systems and a standardized adjustable steel connection have been developed and tested, to facilitate circular economy as well as the ... [more ▼]

A series of demountable connections for reusable composite flooring systems and a standardized adjustable steel connection have been developed and tested, to facilitate circular economy as well as the serial production of structural elements and the suitability to be added into BIM or other digital tools. Demountable beam and floor elements and adjustable steel con-nections form the basis of a Lego-liked ‘plug and play’ circular framed structural system. This paper presents the proposed circular system, the results from experiments and finite element analyses and indicates the analysing methods for structural engineers to open a path way for fully implementation of the structures ‘as built’ into digital tools, fabrication and construction. [less ▲]

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See detailIntegration of young migrants in Luxembourg: A focus on social identity and intergroup processes
Albert, Isabelle UL; Gilodi, Amalia UL; Oliveira, José UL et al

Scientific Conference (2022, August 26)

In the past years, more and more young migrants from third countries have arrived to Europe. While the economies of ageing European societies can profit from an influx of young people in their labour ... [more ▼]

In the past years, more and more young migrants from third countries have arrived to Europe. While the economies of ageing European societies can profit from an influx of young people in their labour market, the integration of young third-country nationals poses also challenges both to individuals and societies. The integration of young migrants is a dynamic process that encompasses developmental and adaptive processes at multiple levels and over time. In particular young migrants in vulnerable conditions might be at risk for social exclusion. In order to understand the factors that foster or hinder integration, it is therefore particularly important to analyze the ingroup-outgroup processes involved here from a societal, institutional and individual perspective. The present study is part of the larger EU-funded H2020 MIMY project (EMpowerment through liquid Integration of Migrant Youth in vulnerable conditions) which involves 13 multinational and interdisciplinary partners to study the integration processes of young non-EU migrants across 9 countries (Luxembourg, Germany, United Kingdom, Sweden, Norway, Italy, Poland, Romania, and Hungary). The MIMY project applies a mixed methods approach, including secondary data analysis as well as qualitative data from young migrants and their parents, from host society nationals and stakeholders through narrative, biographical and expert interviews as well as focus groups. For the present contribution, we will concentrate on qualitative data collected in Luxembourg. More precisely, drawing on focus group interviews regarding the challenges and resources in the integration processes of migrant youth, we will analyze here the ingroup-outgroup processes as described by migrant youth themselves as well as by migrant parents of adolescents/emerging adults living in Luxembourg. We will in particular identify processes of social identity, intergroup attitudes and patterns of social contact. Thereby, a special focus will be put on the experiences of social inclusion/exclusion and host societal attitudes toward migrants as experienced by our study participants. Our results will be discussed in relation to current integration policies, and ideas for an improvement of the situation of young migrants in Luxembourg and Europe will be formulated. [less ▲]

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See detailDeep Learning-based Intra-slice Attack Detection for 5G-V2X Sliced Networks
Boualouache, Abdelwahab UL; Djaidja, Taki Eddine Toufik; Senouci, Sidi-Mohammed et al

in Deep Learning-based Intra-slice Attack Detection for 5G-V2X Sliced Networks (2022, August 25)

Connected and Automated Vehicles (CAVs) represent one of the main verticals of 5G to provide road safety, road traffic efficiency, and user convenience. As a key enabler of 5G, Network Slicing (NS) aims ... [more ▼]

Connected and Automated Vehicles (CAVs) represent one of the main verticals of 5G to provide road safety, road traffic efficiency, and user convenience. As a key enabler of 5G, Network Slicing (NS) aims to create Vehicle-to-Everything (V2X) network slices with different network requirements on a shared and programmable physical infrastructure. However, NS has generated new network threats that might target CAVs leading to road hazards. More specifically, such attacks may target either the inner functioning of each V2X-NS (intra-slice) or break the NS isolation. In this paper, we aim to deal with the raised question of how to detect intra-slice V2X attacks. To do so, we leverage both Virtual Security as a Service (VSaS) concept and deep learning (DL) to deploy a set of DL-empowered security Virtual Network Functions (sVNFs) within V2X-NSs. These sVNFs are in charge of detecting such attacks, thanks to a DL model that we also build in this work. The proposed DL model is trained, validated, and tested using a publicly available dataset. The results show the efficiency and accuracy of our scheme to detect intra-slice V2X attacks. [less ▲]

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See detailPolishing the Image of a Nation-State: Luxembourg and the Uses of the Past since the 1990s
Spirinelli, Fabio UL

Scientific Conference (2022, August 18)

Since the 1990s the Luxembourg government has increasingly used the past to improve the country’s image. Though this use of history was not new, it has evolved significantly from the 1990s onward, both ... [more ▼]

Since the 1990s the Luxembourg government has increasingly used the past to improve the country’s image. Though this use of history was not new, it has evolved significantly from the 1990s onward, both due to international influences and to specifically Luxembourgish developments. The transformation of the cultural landscape, the organisation of large events, and the European integration process are some examples. The contribution will analyse the uses of the past by public authorities in Luxembourg within this context. The paper will cover a series of key events and initiatives since the 1990s. It aims to understand how history has been used and shaped to promote a national identity and improve Luxembourg’s image, from the 150th anniversary of independence in 1989 to the more recent nation-branding initiatives. It investigates what kind of narratives were disseminated, who the involved stakeholders were, and whether tensions existed in this process. [less ▲]

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See detailOrganising a “Temporary History Lab” in Esch-sur-Alzette (2019)
Harnoncourt, Julia UL; van de Maele, Jens UL

Scientific Conference (2022, August 17)

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See detailPublic Engagement with Web Archives
Brügger, Niels; Schafer, Valerie UL

Scientific Conference (2022, August 17)

With a view to ensuring future access to digital cultural heritage, the first Web collections were established in the mid-1990s. To date there exist for example some 25 national Web archives in Europe ... [more ▼]

With a view to ensuring future access to digital cultural heritage, the first Web collections were established in the mid-1990s. To date there exist for example some 25 national Web archives in Europe that collect and preserve Web material and the Internet Archive has saved 651 billion pages since 1996. However, research projects based on the archived Web rarely engage with or include the general public. There are several reasons for this limited use of Web archives: there is a lack of awareness and a lack of examples demonstrating their value; to use them requires skills that many people do not have; and no quick and easy access is available (Winters, 2017). However, several research projects were developed which are of interest for the general public: some of them have studied national Web ('Probing a nation’s Web sphere — the historical development of the Danish Web' (DK, 2013-), 'Big UK Domain Data for the Arts and Humanities' (UK, 2014-15), etc.), others have focused on the web activity in relation to an event, for instance the terrorist attacks in France (‘Archives sauvegarde attentats Paris' (FR, 2016)). In 2020, a nationally funded researcher network has been established (WARCnet, DK). Web archiving initiatives have also been very reactive during the COVID crisis (and sometimes invited the public to nominate URLs). This resulted in huge national collections and a unique collection of international web archives gathered by the IIPC thanks to the collaboration of more than 30 web archiving institutions (https://archive-it.org/collections/13529). As leaders of and/or participants in several of these initiatives, the proposers aim to stimulate greater involvement of the public with the treasure trove to be found in Web archives. Web archives contain their histories, but these important stories are largely hidden from view. The proposers want to create a frame for developing an ambitious relationship with the public, by identifying the challenges and limits to their involvement in Digital Public History at the level of: - Web archiving How/why could we better include publics in the selection of archived content? What is the added value? What are the constraints (i.e legal deposit)? How can we make information about access to Web archives available and raise public awareness of Web archiving? - Selection and analysis of archives Web archives require good knowledge of the Web archiving process if they are to be used effectively. The identification of scarce existing resources for the general public will be coupled with a perspective on needs and tools. - Dissemination Legal and ethical issues (author rights, gender bias, etc.) must be taken into account and the very notion of what is public must be refined. All these elements advocate for an in-depth reflection and this working group is the starting point for a better inclusion of audiences in the creation/selection, use and enhancement of Web archives. [less ▲]

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See detailTowards Refined Classifications Driven by SHAP Explanations
Arslan, Yusuf UL; Lebichot, Bertrand UL; Allix, Kevin UL et al

in Holzinger, Andreas; Kieseberg, Peter; Tjoa, A. Min (Eds.) et al Machine Learning and Knowledge Extraction (2022, August 11)

Machine Learning (ML) models are inherently approximate; as a result, the predictions of an ML model can be wrong. In applications where errors can jeopardize a company's reputation, human experts often ... [more ▼]

Machine Learning (ML) models are inherently approximate; as a result, the predictions of an ML model can be wrong. In applications where errors can jeopardize a company's reputation, human experts often have to manually check the alarms raised by the ML models by hand, as wrong or delayed decisions can have a significant business impact. These experts often use interpretable ML tools for the verification of predictions. However, post-prediction verification is also costly. In this paper, we hypothesize that the outputs of interpretable ML tools, such as SHAP explanations, can be exploited by machine learning techniques to improve classifier performance. By doing so, the cost of the post-prediction analysis can be reduced. To confirm our intuition, we conduct several experiments where we use SHAP explanations directly as new features. In particular, by considering nine datasets, we first compare the performance of these "SHAP features" against traditional "base features" on binary classification tasks. Then, we add a second-step classifier relying on SHAP features, with the goal of reducing false-positive and false-negative results of typical classifiers. We show that SHAP explanations used as SHAP features can help to improve classification performance, especially for false-negative reduction. [less ▲]

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See detailUnlinkability of an Improved Key Agreement Protocol for EMV 2nd Gen Payments
Horne, Ross James UL; Mauw, Sjouke UL; Yurkov, Semen UL

Scientific Conference (2022, August 10)

To address known privacy problems with the EMV standard, EMVCo have proposed a Blinded Diffie-Hellman key establishment protocol, which is intended to be part of a future 2nd Gen EMV protocol. We point ... [more ▼]

To address known privacy problems with the EMV standard, EMVCo have proposed a Blinded Diffie-Hellman key establishment protocol, which is intended to be part of a future 2nd Gen EMV protocol. We point out that active attackers were not previously accounted for in the privacy requirements of this proposal protocol, and demonstrate that an active attacker can compromise unlinkability within a distance of 100cm. Here, we adopt a strong definition of unlinkability that does account for active attackers and propose an enhancement of the protocol proposed by EMVCo. We prove that our protocol does satisfy strong unlinkability, while preserving authentication. [less ▲]

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See detailProfiling the real world potential of neural network compression
Lorentz, Joe UL; Hartmann, Thomas; Moawad, Assaad et al

in 2022 IEEE International Conference on Omni-layer Intelligent Systems (COINS), Barcelona 1-3 August 2022 (2022, August 01)

Abstract—Many real world computer vision applications are required to run on hardware with limited computing power, often referred to as ”edge devices”. The state of the art in computer vision continues ... [more ▼]

Abstract—Many real world computer vision applications are required to run on hardware with limited computing power, often referred to as ”edge devices”. The state of the art in computer vision continues towards ever bigger and deeper neural networks with equally rising computational requirements. Model compression methods promise to substantially reduce the computation time and memory demands with little to no impact on the model robustness. However, evaluation of the compression is mostly based on theoretic speedups in terms of required floating-point operations. This work offers a tool to profile the actual speedup offered by several compression algorithms. Our results show a significant discrepancy between the theoretical and actual speedup on various hardware setups. Furthermore, we show the potential of model compressions and highlight the importance of selecting the right compression algorithm for a target task and hardware. The code to reproduce our experiments is available at https://hub.datathings.com/papers/2022-coins. [less ▲]

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See detailNonlinear local solver
Habera, Michal UL; Zilian, Andreas UL

Scientific Conference (2022, August)

Many engineering applications require solution of a global finite element problem coupled with nonlinear equations of local nature. Local in the sense, that for a known global state the local solution ... [more ▼]

Many engineering applications require solution of a global finite element problem coupled with nonlinear equations of local nature. Local in the sense, that for a known global state the local solution could be found on cell-by-cell basis. Examples include plastic deformation problems, static condensation (hybridization) of displacement-stress formulation or just a simple nonlinear constitutive laws to be satisfied at each quadrature point. These types of problems either required special libraries and extensions in order to be solved with FEniCS (and FEniCS-X) tools, or lead to very slow implementations due to hacks and tricks needed to achieve the solution (e.g. monolithic schemes which increase the matrix problem size). In this talk a unified approach tailored for the current state of FEniCS-X interfaces is presented. The approach computes consistent global tangent operator for nonlinear problems. In addition, local equations are formulated symbolically in UFL, and their derivatives are therefore computed automatically. Several low-level examples (incl. plasticity with symbolic yield surface, nonlinear static condensation and materials with implicit constitutive laws) that demonstrate the main concepts are presented. Finally, high-level wrappers for this functionality are presented. These come as a part of package `dolfiny` (https://github.com/michalhabera/dolfiny). [less ▲]

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See detailNonlinear analysis of thin-walled structures based on tangential differential calculus with FEniCSx
Zilian, Andreas UL; Habera, Michal UL

Scientific Conference (2022, August)

We present an approach to implement the Tangential Differential Calculus (TDC) for a variety of thin-walled structures (beams, membranes, shells) in the framework of nonlinear kinematics and/or material ... [more ▼]

We present an approach to implement the Tangential Differential Calculus (TDC) for a variety of thin-walled structures (beams, membranes, shells) in the framework of nonlinear kinematics and/or material behaviour. In contrast to classical formulations the TDC describes kinematics, equilibrium and constitutive relation of the thin structure (as two-dimensional manifold) on the basis of a full three-dimensional deformation state. This allows to introduce the undeformed configuration of e.g. a shell directly in terms of a mesh of topological dimension 2 and geometrical dimension 3. Of particular interest is the use of finite elements of higher-order geometrical order to capture the (interpolated) curvature of the manifold with high accuracy. Numerical examples and reference implementations of this work to support nonlinear stress and post-buckling analyses (using a realisation of the classical arc-length method in FEniCSx) will be provided as a part of the package dolfiny (https://github.com/michalhabera/dolfiny). [less ▲]

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See detailSOniCS: Interfacing SOFA and FEniCS for advanced constitutive models
Mazier, Arnaud UL; El Hadramy, Sidaty; Brunet, Jean-Nicolas et al

Scientific Conference (2022, August)

The Simulation Open Framework Architecture (SOFA) is a software environment for building simulations with a particular focus on real-time medical applications, e.g. surgery. Its scope is far broader than ... [more ▼]

The Simulation Open Framework Architecture (SOFA) is a software environment for building simulations with a particular focus on real-time medical applications, e.g. surgery. Its scope is far broader than the FEniCS Project, encompassing e.g. rigid body dynamics, interfacing with haptic devices, contact and visualisation. Naturally, it also includes some finite element models of soft tissue mechanics, but these capabilities are currently ‘pre-baked’ and limited to a few simple constitutive models. The goal of this work is to incorporate state-of-the-art code generation tools from the FEniCS Project into SOFA in order to hugely increase SOFA’s capabilities in terms of soft tissue mechanics. To this end we have developed a new SOFA plugin named SOniCS. For adding a new material model in SOniCS, the user describes its strain energy density function using UFL (Unified Form Language) syntax. Then, using FFCx (FEniCSx Form Compiler) we generate the C code associated with the kernels corresponding to the automatically differentiated cell-local residual and stiffness forms. Finally, we assemble these kernels in SOFA into global tensors and solve the resulting non-linear systems of equations. The result is that it is now possible to straightforwardly implement complex material models such as the Holzapfel-Ogden anisotropic model into SOFA, and to use them alongside SOFA’s existing strong feature set in medical simulation. [less ▲]

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See detailReal Time Hyper-elastic Simulations with Probabilistic Deep Learning
Deshpande, Saurabh UL; Lengiewicz, Jakub UL; Bordas, Stéphane UL

in 15th World Congress on Computational Mechanics (WCCM-XV) (2022, August)

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See detailNovel Reinforcement Learning based Power Control and Subchannel Selection Mechanism for Grant-Free NOMA URLLC-Enabled Systems
Tran, Duc Dung UL; Ha, Vu Nguyen UL; Chatzinotas, Symeon UL

in Proceedings of 2022 IEEE 95th Vehicular Technology Conference: (VTC2022-Spring) (2022, August)

Reducing waiting time due to scheduling process and exploiting multi-access transmission, grant-free non-orthogonal multiple access (GF-NOMA) has been considered as a promising access technology for URLLC ... [more ▼]

Reducing waiting time due to scheduling process and exploiting multi-access transmission, grant-free non-orthogonal multiple access (GF-NOMA) has been considered as a promising access technology for URLLC-enabled 5G system with strict requirements on reliability and latency. However, GF-NOMAbased systems can suffer from severe interference caused by the grant-free (GF) access manner which may degrade the system performance and violate the URLLC-related requirements. To overcome this issue, the paper proposes a novel reinforcementlearning (RL)-based random access (RA) protocol based on which each device can learn from the previous decision and its corresponding performance to select the best subchannels and transmit power level for data transmission to avoid strong cross-interference. The learning-based framework is developed to maximize the system access efficiency which is defined as the ratio between the number of successful transmissions and the number of subchannels. Simulation results show that our proposed framework can improve the system access efficiency significantly in overloaded scenarios. [less ▲]

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See detailGoodness Groceries! A mobile sustainable food shopping app advocating for food literacy and ethical choices. Entailments for suppliers, consumers and researchers.
Reckinger, Rachel UL; Kapgen, Diane UL; Korjonen, Maria Helena UL et al

Scientific Conference (2022, August)

Within the currently rising concerns around sustainability of food systems, in the related economic areas of regenerative production modes, responsible supply chains and informed consumption, there often ... [more ▼]

Within the currently rising concerns around sustainability of food systems, in the related economic areas of regenerative production modes, responsible supply chains and informed consumption, there often remains a practice gap between what people know they should do and what they actually do. This is preceded by a knowledge gap: the knowledge of what a sustainable product specifically is tends not to be entirely consensual, blurred with potentially contradicting injunctions between different claims of sustainability. Instead of trying to solve this puzzle with metrics, we propose an App that makes various components of sustainability transparent, thus qualifying sustainability complexity. Our aim is not to hierarchically determine ‘the best’ sustainable choice, but rather to relationally empower consumers to choose the product with the sustainability criteria that most fit their values and priorities. Goodness Groceries is a University of Luxembourg consumer study piloting a mobile sustainable food shopping app in partnership with a supermarket chain. The App acts as a virtual shopping companion providing eco-responsible and ethical product information of selected staple food products, each time for up to four types: local organic, local conventional, imported organic and imported conventional. The information provided is based on self-assessments made by product suppliers. Each food item is granted criteria in the four main areas of Environment, Social Well-being, Economic Well-being and Good Governance, subdivided into relevant indicators (cf. SAFA guidelines, FAO 2014) – marked with easy-to-recognise icons. The user-friendly App is designed to scan alternatives of the same product via a QR code whilst shopping, to analyse if this helps consumers make an informed choice – or not, and why. Starting in Spring 2022, entailments of the (ongoing) study and App in terms of structural obstacles for researchers, necessary supply chain adaptations for suppliers and analysis of consumers’ shopping habits and App usage feedback will be discussed. [less ▲]

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See detailFour Cables-Suspended Parallel Robot with Reconfigurable platform
Golli, H. El; Kumar, Atal Anil UL; Antoine, J.F. et al

Scientific Conference (2022, August)

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See detailTowards verifiable differentially-private polling
Munilla-Garrido, Gonzalo; Sedlmeir, Johannes UL; Babel, Matthias

in Proceedings of the International Conference on Availability, Reliability and Security (2022, August)

Analyses that fulfill differential privacy provide plausible deniability to individuals while allowing analysts to extract insights from data. However, beyond an often acceptable accuracy tradeoff, these ... [more ▼]

Analyses that fulfill differential privacy provide plausible deniability to individuals while allowing analysts to extract insights from data. However, beyond an often acceptable accuracy tradeoff, these statistical disclosure techniques generally inhibit the verifiability of the provided information, as one cannot check the correctness of the participants’ truthful information, the differentially private mechanism, or the unbiased random number generation. While related work has already discussed this opportunity, an efficient implementation with a precise bound on errors and corresponding proofs of the differential privacy property is so far missing. In this paper, we follow an approach based on zero-knowledge proofs (ZKPs), in specific succinct non-interactive arguments of knowledge, as a verifiable computation technique to prove the correctness of a differentially private query output. In particular, we ensure the guarantees of differential privacy hold despite the limitations of ZKPs that operate on finite fields and have limited branching capabilities. We demonstrate that our approach has practical performance and discuss how practitioners could employ our primitives to verifiably query individuals’ age from their digitally signed ID card in a differentially private manner. [less ▲]

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See detailTowards a Framework for Human-Robot Co-creation
Gubenko, Alla UL; Houssemand, Claude UL

Poster (2022, August)

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See detailEtzels Vielvölkerhof – ein Modell europäisch vernetzter Herrschaft?
Bendheim, Amelie UL

Scientific Conference (2022, July 29)

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See detailMultilingualism as Challenge for Luxembourgish Literary Historiography
Glesener, Jeanne UL

Scientific Conference (2022, July 29)

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See detailTowards Online System Identification: Benchmark of Model Identification Techniques for Variable Dynamics UAV Applications
Song, Junlin UL; J. Sanchez-Cuevas, Pedro; Olivares-Mendez, Miguel

Scientific Conference (2022, July 26)

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See detail"Mapping" biographies in relational databases - The case of Luxembourg soldiers in the Second World War
Janz, Nina UL

Scientific Conference (2022, July 25)

The Impact and Legacy of War Experiences in Luxembourg” researches the personal side of the history of Luxembourgish youth born between 1920 and 1927 who were enrolled into German services under the Nazi ... [more ▼]

The Impact and Legacy of War Experiences in Luxembourg” researches the personal side of the history of Luxembourgish youth born between 1920 and 1927 who were enrolled into German services under the Nazi occupation of Luxembourg during World War II. The research focuses on personal testimonies and their individual war experience to uncover these men, women, and families’ individual experiences. Using a relational database to represent their war experiences, we face several challenges, such as a data structure that is too rigid and strict to “map” the fluid and unpredictable life patterns of our study subjects. We developed a data model where we treat different life stations (military unit, POW camp etc.) as equal data levels like our recruits (as persons). Each “life station” or event we treat as a “person” and create a separate “biography” to include all relevant data. Afterwards, we link the life stations or events with the actual person in the database. The aim of my contribution is the “translation” of lives, with its twists and turns into a static data set such as a relational database to map the individual war experiences of our study object. [less ▲]

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See detailDeveloping collaborative practices in ECE in Luxembourg 
Kirsch, Claudine UL

Scientific Conference (2022, July 22)

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See detailHigh-Performance Computing for the simulation of particles with the Discrete Element Method
Besseron, Xavier UL

Scientific Conference (2022, July 21)

In this talk, we will give an overview of the main techniques used for the parallelization of numerical simulations on High-Performance Computing platforms, and provide a particular focus on the Discrete ... [more ▼]

In this talk, we will give an overview of the main techniques used for the parallelization of numerical simulations on High-Performance Computing platforms, and provide a particular focus on the Discrete Element Method (DEM), a numerical method for the simulation of the motion of granular materials. We will cover the main parallelization paradigms and their implementations (shared memory with OpenMP and distributed memory with MPI), present the performance bottlenecks and introduce load-balancing techniques. [less ▲]

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See detailTranslanguaging pedagogy and creative activism for preschool teachers, parents, and children
Aleksic, Gabrijela UL

Scientific Conference (2022, July 14)

There are 64 % of four-year old children who not speak Luxembourgish at home (MENJE, 2018). The government proclaimed multilingual early education mandatory in 2017, obliging teachers to develop ... [more ▼]

There are 64 % of four-year old children who not speak Luxembourgish at home (MENJE, 2018). The government proclaimed multilingual early education mandatory in 2017, obliging teachers to develop children’s Luxembourgish, familiarizing them with French, and valuing their home languages. Thus, the present project was threefold: (1) to offer an 18-hours professional development (PD) course in translanguaging pedagogy to 40 teachers over 6 months, (2) to strengthen home-school collaboration, and (3) to support children’s linguistic, socio-emotional, and cognitive development and engagement in the classroom. The results from teacher questionnaires, focus groups, and interviews, showed that there was some positive change regarding the attitudes towards children’s home languages. The interviews with 17 parents indicated that there was a need for more home-school collaboration. The tests in early literacy and numeracy with 23 preschool children over one year, identified that children performed higher in their home languages. The video observations showed that every time the teacher used children’s languages in the classroom, this impacted positively their well-being. Following the principles of creative activism, the author produced three outcomes: (1) the website with over 100 practical activities on how teachers can involve children’s languages and families, (2) the illustrated book Sumak for parents, showing difficulties with integration in a new country, and (3) the illustrated book, Mara’s song for preschool children, showing how Mara, a girl who is laughed at because of her language and culture, finds her way through singing a song inspired by a bird. [less ▲]

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See detailJewish History and the Politics of Digitisation
Zaagsma, Gerben UL

Scientific Conference (2022, July 13)

This paper discusses the politics of Jewish Studies by focusing on the digitisation of Jewish cultural heritage and its effects for research into Jewish history(ies). In the past few years we have ... [more ▼]

This paper discusses the politics of Jewish Studies by focusing on the digitisation of Jewish cultural heritage and its effects for research into Jewish history(ies). In the past few years we have witnessed the emergence of what could be termed the critical turn in digital humanities with an increasing focus on how digital resources shape various parts of the research process and its outcomes. One aspect of that turn is more attention to digital source criticism and the politics of digitisation of cultural heritage. There are many aspects of digitisation that can be considered “political”, from selection for digitisation to modes of access to broader questions about the political aspects of infrastructure or ‘infrapolitics’. None of these is specific to our digital age nor to Jewish Studies, and historical context is crucially important.  This paper builds upon my recent reseach into the politics of digitisation and considers the case of Jewish Studies, framed within the broader context of the politics of heritage and its preservation. It set outs a number of broad parameters for discussion, with the aim to encourage further debate. Questions to be addressed include: what Jewish heritage is being digitised and which stories about the Jewish past can (and cannot) be told on its basis? Which players are involved in digitisation and how do both top-down national strategies and bottom-up community initiatives guide the process? How do memory politics influence selection processes? And how does transnational heritage fare in an age where many digitisation programs are nationally framed and funded? The paper will use the historical example of the digitisation of Yiddish heritage to illustrate these questions and provide a concrete example.  [less ▲]

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See detailUplink Capacity Optimization for High Throughput Satellites using SDN and Multi-Orbital Dual Connectivity
Dazhi, Michael UL; Al-Hraishawi, Hayder UL; Mysore Rama Rao, Bhavani Shankar UL et al

in IEEE International Conference on Communications (ICC) (2022, July 11)

Dual Connectivity is a key approach to achieving optimization of throughput and latency in heterogeneous networks. Originally a technique introduced by the 3rd Generation Partnership Project (3GPP) for ... [more ▼]

Dual Connectivity is a key approach to achieving optimization of throughput and latency in heterogeneous networks. Originally a technique introduced by the 3rd Generation Partnership Project (3GPP) for terrestrial communications, it is not been widely explored in satellite systems. In this paper, Dual Connectivity is implemented in a multi-orbital satellite network, where a network model is developed by employing the diversity gains from Dual Connectivity and Carrier Aggregation for the enhancement of satellite uplink capacity. An introduction of software defined network controller is performed at the network layer coupled with a carefully designed hybrid resource allocation algorithm which is implemented strategically. The algorithm performs optimum dynamic flow control and traffic steering by considering the availability of resources and the channel propagation information of the orbital links to arrive at a resource allocation pattern suitable in enhancing uplink system performance. Simulation results are shown to evaluate the achievable gains in throughput and latency; in addition we provide useful insight in the design of multi-orbital satellite networks with implementable scheduler design. [less ▲]

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See detailTowards practical Genome-Wide Association Studies: Overview and Challenges
Pascoal, Túlio UL; Decouchant, Jérémie UL; Volp, Marcus UL

Scientific Conference (2022, July 11)

The popularization of large-scale federated Genome-Wide Association Study (GWAS) where multiple data owners share their genome data to conduct federated analytics uncovers new privacy issues that have ... [more ▼]

The popularization of large-scale federated Genome-Wide Association Study (GWAS) where multiple data owners share their genome data to conduct federated analytics uncovers new privacy issues that have remained unnoticed or not given proper attention. Indeed, as soon as a diverse type of interested parties (e.g., private or public biocenters and governmental institutions from around the globe) and individuals from heterogeneous populations are participating in cooperative studies, interdependent and multi-party privacy appear as crucial issues that are currently not adequately assessed. In fact, in federated GWAS environments, the privacy of individuals and parties does not depend solely on their own behavior anymore but also on others, because a collaborative environment opens new credible adversary models. For instance, one might want to tailor the privacy guarantees to withstand the presence of potentially colluding federation members aiming to violate other members' data privacy and the privacy deterioration that might occur in the presence of interdependent genomic data (e.g., due to the presence of relatives in studies or the perpetuation of previous genomic privacy leaks in future studies). In this work, we catalog and discuss the features, unsolved problems, and challenges to tackle toward truly end-to-end private and practical federated GWAS. [less ▲]

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See detailLe parcours de vie entre défense sociale et maladie mentale de Maxence C. Etude d’un cas de dégénéré délinquant dans la Belgique du XXème siècle
Dal Zilio, Samuel UL

Scientific Conference (2022, July 08)

« L’intelligence et le sens moral d’un enfant de 8 ans », c’est par ces mots qu’en août 1933, le médecin-chef de l’Etablissement de Défense Sociale de Tournai qualifie l’état psychique de Maxence C., un ... [more ▼]

« L’intelligence et le sens moral d’un enfant de 8 ans », c’est par ces mots qu’en août 1933, le médecin-chef de l’Etablissement de Défense Sociale de Tournai qualifie l’état psychique de Maxence C., un débile mental (sic) reconnu coupable du chef de vol et d’escroquerie mais jugé incapable du contrôle de ses actions. A l’aube de ses 27 ans, ce « demi-fou » enchaîne depuis vingt ans les séjours en institution. Entre internats médico-pédagogiques, asiles d’aliénés et établissements de défense sociale, le parcours de vie de Maxence C. est jalonné de multiples interactions avec les autorités judiciaires, médicales et administratives qui tantôt le condamne à l’incarcération, tantôt favorise sa réhabilitation au sein de la société. Arrimé à cette identité de marginal dans un « monde faux et crapuleux » selon ses dires, Maxence C. peine à acquérir une pleine autonomie synonyme de liberté (re)trouvée. Travail, suivi médical, tutelle morale et accompagnement familial semblent toujours vains. Devenu sexagénaire, il demeure ainsi un « danger social » balloté entre asiles-prisons et prisons-asiles aux quatre coins du royaume. A travers l’examen minutieux d’un dossier de plusieurs centaines de pages élaboré par la Commission de défense sociale de Forest, cette communication propose de mettre en lumière la complexité de la trajectoire de vie d’un individu à la fois criminel et aliéné, visé par un dispositif hybride de sécurité et de soins. Si cette étude considère la perspective du patient à travers une histoire par le bas, elle dépasse celle-ci pour entrouvrir la possibilité d’un récit polyphonique sur des temps longs qui confronte de multiples voix (celle de l’administration et de la police, celle des médecins et des magistrats, celle du malade et de ses proches). Nourrit par les enseignements de la micro-histoire et de l’étude de cas dans la recherche historique, cette contribution offre un regard original sur l’évolution des normes qui conditionnent un mouvement vers ou, au contraire, hors de l’institution. Les phases d’entrée et de sortie des établissements sont en effet des moments charnières de l’affirmation du pouvoir des acteurs. Dès lors, quels sont les motifs à une incarcération et quelles sont les conditions à un élargissement ? Comment s’organise la prise de la décision entre les différents intervenants ? Et qui en assure le contrôle et le suivi ? Enfin, quelles sont les marges de manœuvre et les capacités d’actions du « malade » face à eux ? Cette étude d’une trajectoire de vie individuelle constitue également une opportunité de s’interroger sur l’évolution des systèmes de prise en charge des criminels malades mentaux dans le royaume au XXème siècle. Ainsi durant l’existence de Maxence C. se créent de nouvelles structures psychiatriques (dispensaires d’hygiène mentale, annexes psychiatriques dans les prisons et les hôpitaux généraux, établissements de défense sociale, etc.) se construisent des nouvelles politiques sociales (INAMI, CPAS, mutualités, etc.), s’élaborent des nouvelles législations (loi relative à la défense sociale, au handicap, à la maladie mentale), s’affirment de nouveaux métiers de la santé mentale (psychologue, infirmière psychiatrique, assistants sociaux, etc.), s’établissent de nouveaux rapports à la folie, au handicap et à la criminalité. [less ▲]

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See detailOptimising Autonomous Robot Swarm Parameters for Stable Formation Design
Stolfi Rosso, Daniel UL; Danoy, Grégoire UL

in Proceedings of the Genetic and Evolutionary Computation Conference (2022, July 08)

Autonomous robot swarm systems allow to address many inherent limitations of single robot systems, such as scalability and reliability. As a consequence, these have found their way into numerous ... [more ▼]

Autonomous robot swarm systems allow to address many inherent limitations of single robot systems, such as scalability and reliability. As a consequence, these have found their way into numerous applications including in the space and aerospace domains like swarm-based asteroid observation or counter-drone systems. However, achieving stable formations around a point of interest using different number of robots and diverse initial conditions can be challenging. In this article we propose a novel method for autonomous robots swarms self-organisation solely relying on their relative position (angle and distance). This work focuses on an evolutionary optimisation approach to calculate the parameters of the swarm, e.g. inter-robot distance, to achieve a reliable formation under different initial conditions. Experiments are conducted using realistic simulations and considering four case studies. The results observed after testing the optimal configurations on 72 unseen scenarios per case study showed the high robustness of our proposal since the desired formation was always achieved. The ability of self-organise around a point of interest maintaining a predefined fixed distance was also validated using real robots. [less ▲]

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See detailIf there’s something strange in your [cyber]hood – who you gonna call?
Schmitz, Sandra UL

Scientific Conference (2022, July 07)

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See detailCentrality and city size effects on NO2 ground and tropospheric concentrations within European cities
Wei, Yufei UL; Caruso, Geoffrey UL; Lemoy, Rémi

Scientific Conference (2022, July 06)

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See detailTransatlantic Chattel Slavery, 1815–1888
Erpelding, Michel UL

in Lovall, Erin; Stefanelli, Justine (Eds.) Reparations Under International Law for Enslavement of African Persons in the Americas and the Caribbean: Proceedings of the Symposium, May 20–21, 2021 (2022, July 06)

This paper addresses the question of the legality and illegality of slavery-related practices during the 19th century under Western international law.

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See detailQuality of Work and Quality of Employment Profiles and their longitudinal impact on well-being
Sischka, Philipp UL; Fernandez de Henestrosa, Martha UL; Steffgen, Georges UL

Scientific Conference (2022, July 06)

Many studies on job quality operationalize job quality as a composite indicator (Munoz de Bustillo et al., 2011) and investigate its link with different well-being outcomes or investigate the incremental ... [more ▼]

Many studies on job quality operationalize job quality as a composite indicator (Munoz de Bustillo et al., 2011) and investigate its link with different well-being outcomes or investigate the incremental effects of specific job characteristics on well-being. However, these variable-centered approaches on job quality ignore the fact that certain job characteristic configurations cluster in specific employee groups (Van Aeren et al., 2014). Thus, the current longitudinal study employs a person-centered approach (i.e., latent profile and transition analysis (LPA/LTA), e.g., Spurk et al., 2020) to identify groups of employees that show different job characteristic profiles (over time). Data were collected via CATI or CAWI within a stratified random sample from Luxembourg’s working population (nWave 1 = 1,689; nWave 2 = 848). The survey contains eleven quality of work and six quality of employment dimensions that were used as indicators for the latent profile analysis. Moreover, the survey contains different mental health and work-related attitudinal outcomes. Fit indices and substantive interpretability/utility were jointly considered to determine the number of profiles. To explore the relationships between the latent categorical variable and the other variables, we followed the three-step procedure (e.g., Asparouhov & Muthén, 2014) LPA revealed five profiles, i.e., poor working conditions (1), medium working conditions, high work intensity (2), high working conditions, medium work intensity (3), high working conditions, high work intensity and physical demands (4), medium working conditions, low work intensity (5). Cross-sectionally, these profiles were meaningfully linked with mental and attitudinal outcomes. LTA suggests the stability of these profiles within one year, with varying impact depending on mental health and work-related attitudinal outcome. Scholars and policy makers need to be aware of job characteristic configurations. To promote employee’s well-being organizations and policy makers need to redesign the ecological contexts of working conditions depending on its profiles. [less ▲]

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See detailWhich Factors Play a Role in Coco Issuance? Evidence from European Banks.
Wolff, Christian UL

Scientific Conference (2022, July 06)

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See detailClimate Risk and Price Jumps
Lehnert, Thorsten UL

Scientific Conference (2022, July 05)

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See detailHybrid Active-Passive Reconfigurable Intelligent Surface-Assisted Multi-User MISO Systems
Nguyen, Nhan T.; Nguyen, V.-Dinh; Wu, Qingqing et al

Poster (2022, July 04)

We consider a multi-user multiple-input single- output (MISO) communications system which is assisted by a hybrid active-passive reconfigurable intelligent surface (RIS). Unlike conventional passive RISs ... [more ▼]

We consider a multi-user multiple-input single- output (MISO) communications system which is assisted by a hybrid active-passive reconfigurable intelligent surface (RIS). Unlike conventional passive RISs, hybrid RIS is equipped with a few active elements with the ability to reflect and amplify incident signals to significantly improve the system performance. Towards a fairness design, we maximize the minimum rate among all users through jointly optimizing the transmit beamforming vectors and RIS reflecting/amplifying coefficients. Combining tools from block coordinate ascend and successive convex approximation, the challenging nonconvex problem is efficiently solved by a low- complexity iterative algorithm. The numerical results show that a hybrid RIS with 4 active elements out of a total of 50 elements with a power budget of −1 dBm offers an improvement of up to 80% to the considered system, while that achieved by a fully passive RIS is only 27% [less ▲]

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See detailEconomic Sanctions and International Investment Law: Investor and State Defences
Garcia Olmedo, Javier UL

Scientific Conference (2022, July 04)

This workshop examines the law and practice of economic sanctions in light of current developments in the Ukraine-Russia conflict. It explores the legality and implementation of, and possible challenges ... [more ▼]

This workshop examines the law and practice of economic sanctions in light of current developments in the Ukraine-Russia conflict. It explores the legality and implementation of, and possible challenges to, economic sanctions imposed by a number of international actors (including the US, the EU and the UK), as well as their potential impact on businesses and dispute resolution. [less ▲]

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See detailDIE GESANGSCHULE FÜR DIE "LITURGIE-SÄNGER" IM PREUßISCHEN MILITÄR VON J.D.C. EINBECK (BERLIN 1829)
Brusniak, Friedhelm; Sagrillo, Damien François UL; Heidler, Manfred

in Sagrillo, Damien François (Ed.) International Wind Music Conference, Bolzano 14-18 July 2022 (2022, July 01)

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See detailPourquoi les enseignants décident-ils de s'ouvrir aux familles ? résultats issus d'une consultation nationale au Grand-Duché du Luxembourg
Poncelet, Débora UL; Tinnes, Mélanie UL; Dierendonck, Christophe UL

Scientific Conference (2022, July 01)

En décembre 2021, une enquête, intitulée « Consultation des acteurs de l’école fondamentale. Une étude scientifique participative » a permis la collecte de données auprès des enseignants de l’école ... [more ▼]

En décembre 2021, une enquête, intitulée « Consultation des acteurs de l’école fondamentale. Une étude scientifique participative » a permis la collecte de données auprès des enseignants de l’école fondamentale et des éducateurs gradués. La thématique des relations école-famille a constitué un des aspects investigués dans l’étude. Depuis une vingtaine d’années, un intérêt croissant pour la thématique est observé. Une revue de la littérature récente (par exemple, Axford et al., 2019 ; Englund et al., 2004 ; Kim, Mok & Seidel, 2020, Roy & Giraldo-García, 2018 ; Huat See & Gorard, 2015), a montré à quel point les relations école-famille ainsi que l’engagement parental dans la scolarité de l’enfant pouvaient avoir une influence significative et positive à la fois sur les performances scolaires mais aussi sur des variables conatives (motivation scolaire, engagement ou adoption de comportements scolairement attendus). En outre, étant donné la grande diversité culturelle et socioéconomique des parents dont les enfants fréquentent l’école fondamentale comme la place accordée au partenariat avec les familles dans la loi scolaire, cette thématique est apparue comme incontournable pour le recueil de données. La théorie du comportement planifié (TCP) a été retenue comme un des modèles théorique et d’analyse des données collectées (voir exemple à ce sujet, Ajzen, 1991 ; Armitage et Conner, 2001). Ce modèle théorique vise à prédire et à expliquer un comportement au départ d’un processus cognitif et émotionnel incluant quatre éléments distincts : (1) les attitudes envers le comportement cible, (2) les normes subjectives en lien avec ce comportement, (3) le contrôle comportemental perçu et (4) l’intention d’adopter le comportement cible. Nous chercherons par conséquent à mettre en évidence l’intention des acteurs interrogés d’adopter des comportements propices à l’ouverture et à la communication envers les familles sur la base de leurs attitudes explicites. C’est ainsi que les conceptions et attitudes spécifiques, instrumentales comme affectives, ont été étudiées au départ de 6 items dont cinq sont originaux et un issu de l’instrument de Cárcamo-Vásquez & Rodríguez-Garcés (2015). En ce qui concerne les pratiques relatives à la relation école-famille, elles ont été observées par le biais de deux aspects : 1) la qualité des relations école-famille actuelles telles que perçues par les répondants (Vickers & Mincke, 1995 ; Dawson & Wymbs, 2016) et 2) les actions mises en œuvre pour susciter l’engagement des parents dans l’éducation scolaire de leur enfant soit à domicile, soit à l’école, soit par le biais des communications avec l’école (Hoover-Dempsey & Sandler, 2005 ; Manz, Fantuzzo & Power, 2004). Après avoir décrit la population interrogée et fournit des informations importantes sur le contexte de l’institution scolaire luxembourgeoise en matière d’hétérogénéité des publics, nous présenterons les premiers résultats de l’enquête en ce qui concerne la thématique des relations école-famille selon la théorie du comportement planifié. Bibliographie Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50, 179–211. https://doi: 10.1016/0749-5978(91)90020-T Armitage, C. & Conner, M. (2001). Efficacy of the Theory of Planned Behaviour: A meta-analytic review. British Journal of Social Psychology, 40, 471-499. https://doi.org/10.1348/014466601164939 Axford, N., Berry, V., Lloyd, J., Moore, D., Rogers, M., Hurst, A., Blockley, K., Durkin,H. and Minton, J. (2019). How Can Schools Support Parents’ Engagement in their Children’s Learning? Evidence from Research and Practice. London: Education Endowment Foundation. Report available from: https://educationendowmentfoundation.org.uk/evidence-summaries/evidence-reviews/parental-engagement/ (retrieved February 2022). Cárcamo-Vásquez, H., Rodríguez-Garcés, C. (2015). Rol parental educativo: aproximación a las percepciones que poseen los futuros profesores. Educ., 18(3), 456-470. https://DOI: 10.5294/edu.2015.18.3.5 Dawson, A. E., & Wymbs, B. T. (2016). Validity and Utility of the Parent–Teacher Relationship Scale–II. Journal of Psychoeducational Assessment, 34(8), 751–764. https://doi.org/10.1177/0734282915627027   Englund, M. M., Luckner, A. E., Whaley, G. J. L., & Egeland, B. (2004). Children's Achievement in Early Elementary School: Longitudinal Effects of Parental Involvement, Expectations, and Quality of Assistance. Journal of Educational Psychology, 96(4), 723–730. https://doi.org/10.1037/0022-0663.96.4.723 Hoover-Dempsey, K.V., & Sandler, H.M. (2005). Final Performance Report for OERI Grant # R305T010673. The Social Context of Parental Involvement: A Path to Enhanced Achievement. Presented to Project Monitor, Institute of Education Sciences, U.S. Department of Education, March 22, 2005. Huat See, B., & Gorard, S. (2015). The role of parents in young people’s education—a critical review of the causal evidence. Oxford Review of Education, 41, 346-366. Kim, Y., Mok, S.Y., & Seidel, T. (2020). Parental influences on immigrant students' achievement-related motivation and achievement: A meta-analysis. Educational Research Review, 30, 1-19. https://doi.org/10.1016/j.edurev.2020.100327 Manz, P. H., Fantuzzo, J. W., & Power, T. J. (2004). Multidimensional assessment of family involvement among urban elementary students. Journal of School Psychology, 42(6), 461–475. https://doi.org/10.1016/j.jsp.2004.08.002 Roy, M., & Giraldo-García, R. (2018). The role of parental involvement and social/emotional skills in academic achievement: Global perspectives. The School Community Journal, 28(2), 29–46. Vickers, H. S., & Minke, K. M. (1995). Exploring parent-teacher relationships: Joining and communication to others. School Psychology Quarterly, 10(2), 133–150. https://doi.org/10.1037/h0088300 [less ▲]

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See detailUnderstanding Content Bias: Qualitative research supports computational methods
Hoehn, Sviatlana UL; Lewandowska-Tomaszczyk, Barbara; Mauw, Sjouke UL et al

Scientific Conference (2022, July 01)

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See detailAutonomous control for satellite rendezvous in near-Earth orbits
Muralidharan, Vivek UL; Martinez Luna, Carol UL; Zinys, Augustinas et al

Scientific Conference (2022, July)

CubeSats are being deployed for a number of activities including Earth observation, telecommunications, scientific experiments, and due to their low cost and flexibility, more often than not, they are ... [more ▼]

CubeSats are being deployed for a number of activities including Earth observation, telecommunications, scientific experiments, and due to their low cost and flexibility, more often than not, they are even being considered for use in On-Orbit Servicing (OOS) and debris removal missions. This investigation focuses on using the CubeSat technology to perform autonomous proximity operations with passive target bodies including satellites or space debris. The nonlinear coupled attitude and orbit dynamics for the chaser and the target bodies are modelled and simulated. A nonlinear optimal controller identifies an appropriate rendezvous path. A vision-based navigation system on the chaser satellite records the pose of the target body. The pose observations with stochastic uncertainties are processed using a Kalman filter, and offer state feedback along the satellite path. Such observations in conjunction with the postulated linear control algorithm anchor the chaser to approach the target by maintaining appropriate relative configuration. The linear controller delivers regular maneuvers to compensate for any deviations from the identified reference path. A close-range rendezvous operation is illustrated in a Mission Design Simulator (MDS) tool. [less ▲]

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See detailPotentials of sector coupling to improve the resilience of electricity and gas networks
Leinauer, Christina; Hanny, Lisa; Bhuiyan, Rajon UL et al

in Conference handbook and abstracts of the 32nd European Conference on Operational Research (EURO 2022) (2022, July)

Global warming leads to an increase in extreme weather events that considerably threaten critical infrastructures (e.g., electricity or gas networks). The failure of one critical infrastructure may have ... [more ▼]

Global warming leads to an increase in extreme weather events that considerably threaten critical infrastructures (e.g., electricity or gas networks). The failure of one critical infrastructure may have far-reaching consequences triggering a “cascade of failures” that affects other critical infrastructures. As extreme weather events usually hit affected regions unexpectedly, flexibility in energy systems is key to sustain resilience and rapidly respond to changing conditions, e.g., failed network lines. Hence, we analyze sector coupling (SC) as one option to increase flexibility and exploit synergies between electricity and gas networks. We investigate SC investments that allow for a bi-directional conversion of gas and electricity in the form of gas-fired power plants or power-to-X technologies and their effect on resilience. We propose a two-level market model where, in the upper-level problem, long-term investments in SC technologies are made in anticipation of short-term market clearing as well as uncertain failures and, in the lower-level problem, SC technologies may be activated. We model extreme weather events as a set of discrete scenarios that pose an external risk to the energy system. In our paper, we derive optimal SC investments representing a trade-off between enhancing system resilience and increasing investments. Moreover, we derive optimal SC responses for selected weather events to guide the operation of SC plants under extreme conditions. [less ▲]

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See detailOn the Impacts of Phase Shifting Design and Eavesdropping Uncertainty on Secrecy Metrics of RIS-aided Systems
Kong, Long; Kisseleff, Steven UL; Chatzinotas, Symeon UL et al

in Proceedings of Joint European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit) (2022, July)

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See detailAggregating and Consolidating two High Performant Network Topologies: The ULHPC Experience
Varrette, Sébastien UL; Cartiaux, Hyacinthe UL; Valette, Teddy UL et al

in ACM Practice and Experience in Advanced Research Computing (PEARC'22) (2022, July)

High Performance Computing (HPC) encompasses advanced computation over parallel processing. The execution time of a given simulation depends upon many factors, such as the number of CPU/GPU cores, their ... [more ▼]

High Performance Computing (HPC) encompasses advanced computation over parallel processing. The execution time of a given simulation depends upon many factors, such as the number of CPU/GPU cores, their utilisation factor and, of course, the inter- connect performance, efficiency, and scalability. In practice, this last component and the associated topology remains the most significant differentiators between HPC systems and lesser perfor- mant systems. The University of Luxembourg operates since 2007 a large academic HPC facility which remains one of the reference implementation within the country and offers a cutting-edge re- search infrastructure to Luxembourg public research. The main high-bandwidth low-latency network of the operated facility relies on the dominant interconnect technology in the HPC market i.e., Infiniband (IB) over a Fat-tree topology. It is complemented by an Ethernet-based network defined for management tasks, external access and interactions with user’s applications that do not support Infiniband natively. The recent acquisition of a new cutting-edge supercomputer Aion which was federated with the previous flag- ship cluster Iris was the occasion to aggregate and consolidate the two types of networks. This article depicts the architecture and the solutions designed to expand and consolidate the existing networks beyond their seminal capacity limits while keeping at best their Bisection bandwidth. At the IB level, and despite moving from a non-blocking configuration, the proposed approach defines a blocking topology maintaining the previous Fat-Tree height. The leaf connection capacity is more than tripled (moving from 216 to 672 end-points) while exhibiting very marginal penalties, i.e. less than 3% (resp. 0.3%) Read (resp. Write) bandwidth degradation against reference parallel I/O benchmarks, or a stable and sustain- able point-to-point bandwidth efficiency among all possible pairs of nodes (measured above 95.45% for bi-directional streams). With regards the Ethernet network, a novel 2-layer topology aiming for improving the availability, maintainability and scalability of the interconnect is described. It was deployed together with consistent network VLANs and subnets enforcing strict security policies via ACLs defined on the layer 3, offering isolated and secure net- work environments. The implemented approaches are applicable to a broad range of HPC infrastructures and thus may help other HPC centres to consolidate their own interconnect stacks when designing or expanding their network infrastructures. [less ▲]

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See detailAn Innovative Partitioning Technology for Coupled Software Modules
Peters, Bernhard UL; Besseron, Xavier UL; Peyraut, Alice et al

in Proceedings of the 12th International Conference on Simulation and Modeling Methodologies, Technologies and Applications - SIMULTECH (2022, July)

Multi-physics simulation approaches by coupling various software modules is paramount to unveil the underlying physics and thus leads to an improved design of equipment and a more efficient operation ... [more ▼]

Multi-physics simulation approaches by coupling various software modules is paramount to unveil the underlying physics and thus leads to an improved design of equipment and a more efficient operation. These simulations are in general to be carried out on small to massively parallelised computers for which highly efficient partitioning techniques are required. An innovative partitioning technology is presented that relies on a co-located partitioning of overlapping simulation domains meaning that the overlapping areas of each simulation domain are located at one node. Thus, communication between modules is significantly reduced as compared to an allocation of overlapping simulation domains on different nodes. A co-located partitioning reduces both memory and inter-process communication. [less ▲]

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See detailStudent-Situation Relations in Students’ Real-Time Perceptions of Instructional Quality
Talic, Irma UL; Rauthmann, John F.; Renner, K.-H. et al

Scientific Conference (2022, July)

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See detailErgodic Capacity Analysis of NOMA-Based Two-Way Relaying Systems
ElHalawany, Basem M.; da Costa, Daniel B.; Khan, Wali Ullah UL et al

Poster (2022, July)

In this work, a non-orthogonal multiple access (NOMA) relying on a two-way relaying (TWR) approach is investigated to promote more efficient use of the available spectrum. Specifically, a NOMA-enabled ... [more ▼]

In this work, a non-orthogonal multiple access (NOMA) relying on a two-way relaying (TWR) approach is investigated to promote more efficient use of the available spectrum. Specifically, a NOMA-enabled half-duplex decode-and-forward relay node is used to simultaneously exchange data between two cellular users and a base station (BS), while assuming that the direct links between the two users and the BS are unavailable or negligible. In our analysis, the ergodic capacity is evaluated, in which high signal-to-noise ratio approximations, as well as upper bounds are derived owing to the intractability related to the exact analysis. The results reveal the superiority of the proposed TWR-NOMA scheme compared with the traditional one-way relaying (OWR-NOMA) scheme. Additionally, simulation results show that selecting a relay station (RS) closer to the BS can achieve a higher ergodic sum capacity than selecting a far RS. [less ▲]

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See detailOptimizing the Resource and Job Management System of an Academic HPC and Research Computing Facility
Varrette, Sébastien UL; Kieffer, Emmanuel UL; Pinel, Frederic

in 21st IEEE Intl. Symp. on Parallel and Distributed Computing (ISPDC'22) (2022, July)

High Performance Computing (HPC) is nowadays a strategic asset required to sustain the surging demands for massive processing and data-analytic capabilities. In practice, the effective management of such ... [more ▼]

High Performance Computing (HPC) is nowadays a strategic asset required to sustain the surging demands for massive processing and data-analytic capabilities. In practice, the effective management of such large scale and distributed computing infrastructures is left to a Resource and Job Management System (RJMS). This essential middleware component is responsible for managing the computing resources, handling user requests to allocate resources while providing an optimized framework for starting, executing and monitoring jobs on the allocated resources. The University of Luxembourg has been operating for 15 years a large academic HPC facility which relies since 2017 on the Slurm RJMS introduced on top of the flagship cluster Iris. The acquisition of a new liquid-cooled supercomputer named Aion which was released in 2021 was the occasion to deeply review and optimize the seminal Slurm configuration, the resource limits defined and the sustaining fairsharing algorithm. This paper presents the outcomes of this study and details the implemented RJMS policy. The impact of the decisions made over the supercomputers workloads is also described. In particular, the performance evaluation conducted highlights that when compared to the seminal configuration, the described and implemented environment brought concrete and measurable improvements with regards the platform utilization (+12.64%), the jobs efficiency (as measured by the average Wall-time Request Accuracy, improved by 110.81%) or the management and funding (increased by 10%). The systems demonstrated sustainable and scalable HPC performances, and this effort has led to a negligible penalty on the average slowdown metric (response time normalized by runtime), which was increased by 0.59% for job workloads covering a complete year of exercise. Overall, this new setup has been in production for 18 months on both supercomputers and the updated model proves to bring a fairer and more satisfying experience to the end users. The proposed configurations and policies may help other HPC centres when designing or improving the RJMS sustaining the job scheduling strategy at the advent of computing capacity expansions. [less ▲]

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See detailA comparative study of automatic classifiers to recognize speakers based on fricatives
Hosseini Kivanani, Nina UL; Asadi, Homa; Schommer, Christoph UL et al

Poster (2022, July)

Speakers’ voices are highly individual and for this reason speakers can be identified based on their voice. Nevertheless, voices are often more variable within the same speaker than they are between ... [more ▼]

Speakers’ voices are highly individual and for this reason speakers can be identified based on their voice. Nevertheless, voices are often more variable within the same speaker than they are between speakers, which makes it difficult for humans and machines to differentiate between speakers (Hansen, J. H., & Hasan, T., 2015). To date, various machine learning methods have been developed to recognize speakers based on the acoustic characteristics of their speech; however, not all of them have proven equally effective in speaker identification, and depending on the obtained techniques, the system achieves a different result. Here, different machine learning classifiers have been applied to identify the best classification model (i.e., Naïve Bayes (NB), support vector machines (SVM), random forests (RF), & k-nearest neighbors (KNN)) for categorizing 4 speaking styles based on the segment types (voiceless fricatives) considering acoustic features of center of gravity, standard deviation, and skewness. We used a dataset consisting of speech samples from 7 native Persian subjects speaking in 4 different speaking styles: read, spontaneous, clear, and child-directed speech. The results revealed that the best performing model to predict the speakers based on the segment type was RF model with an accuracy of 81,3%, followed by SVM (76.3%), NB (75.4%), and KNN (74%) (Table 1). Our results showed that the RF performed the best for voiceless fricatives /f/, /s/, and / ʃ / which may indicate that these segments are much more speaker-specific than others (Gordon et al., 2002), and the model performance was low for the voiceless fricatives of /h/ and /x/. Performance can be seen in the confusion matrix (Figure 1), which produced high precision and recall values (above 80%) for /f/, /s/ and / ʃ / (Table 2). We found that the model performance improved when the data related to clear speaking style; the information in individual speakers (i.e., voiceless fricatives) are more distinguishable in clear style than other styles (Table 1). [less ▲]

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See detailManagement of an Academic HPC Research Computing Facility: The ULHPC Experience 2.0
Varrette, Sébastien UL; Cartiaux, Hyacinthe UL; Peter, Sarah UL et al

in 6th High Performance Computing and Cluster Technologies Conference (HPCCT 2022) (2022, July)

With the advent of the technological revolution and the digital transformation that made all scientific disciplines becoming computational, the need for High Performance Computing (HPC) has become and a ... [more ▼]

With the advent of the technological revolution and the digital transformation that made all scientific disciplines becoming computational, the need for High Performance Computing (HPC) has become and a strategic and critical asset to leverage new research and business in all domains requiring computing and storage performance. Since 2007, the University of Luxembourg operates a large academic HPC facility which remains the reference implementation within the country. This paper provides a general description of the current platform implementation as well as its operational management choices which have been adapted to the integration of a new liquid-cooled supercomputer, named Aion, released in 2021. The administration of a HPC facility to provide state-of-art computing systems, storage and software is indeed a complex and dynamic enterprise with the soul purpose to offer an enhanced user experience for intensive research computing and large-scale analytic workflows. Most design choices and feedback described in this work have been motivated by several years of experience in addressing in a flexible and convenient way the heterogeneous needs inherent to an academic environment towards research excellence. The different layers and stacks used within the operated facilities are reviewed, in particular with regards the user software management, or the adaptation of the Slurm Resource and Job Management System (RJMS) configuration with novel incentives mechanisms. In practice, the described and implemented environment brought concrete and measurable improvements with regards the platform utilization (+12,64%), jobs efficiency (average Wall-time Request Accuracy improved by 110,81%), the management and funding (increased by 10%). Thorough performance evaluation of the facility is also presented in this paper through reference benchmarks such as HPL, HPCG, Graph500, IOR or IO500. It reveals sustainable and scalable performance comparable to the most powerful supercomputers in the world, including for energy-efficient metrics (for instance, 5,19 GFlops/W (resp. 6,14 MTEPS/W) were demonstrated for full HPL (resp. Graph500) runs across all Aion nodes). [less ▲]

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See detailIRRMA: An Image Recommender Robot Meeting Assistant
Alcaraz, Benoît UL; Hosseini Kivanani, Nina UL; Najjar, Amro

in IRRMA: An Image Recommender Robot Meeting Assistant (2022, July)

The number of people who attend virtual meetings has increased as a result of COVID-19. In this paper, we present a system that consists of an expressive humanoid social robot called QTRobot, and a ... [more ▼]

The number of people who attend virtual meetings has increased as a result of COVID-19. In this paper, we present a system that consists of an expressive humanoid social robot called QTRobot, and a recommender system that employs natural language processing techniques to recommend images related to the content of the presenter’s speech to the audience in real time. This is achieved utilising the QTRobot’s platform capabilities (microphone, computation power, and Wi-Fi). [less ▲]

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See detailTowards real-time patient-specific breast simulations: from full-field information to surrogate model
Mazier, Arnaud UL; Lavigne, Thomas UL; Lengiewicz, Jakub UL et al

Scientific Conference (2022, July)

In breast cancer treatment, surgery is one of the most common practices [DeSantis et al., 2019]. The surgery involves a complex pipeline, principally due to the difference between the imaging and the ... [more ▼]

In breast cancer treatment, surgery is one of the most common practices [DeSantis et al., 2019]. The surgery involves a complex pipeline, principally due to the difference between the imaging and the surgical posture [Mazier et al., 2021]. Indeed, because of the stance difference, the surgeon has to rely on radioactive or invasive markers to predict the tumor position in the surgical setup. Biomechanical simulations could predict such complex tumor displacements but often require patient-specific data (material properties, organs geometries, or loading and boundary conditions). Full-field acquisitions coupled with landmark identifications allow obtaining relative deformation between the different configurations. Having this information and assuming a finite element model, an identification procedure of the model parameters can be carried out. Finally, finding a suitable computational model allowing for a compromise between accuracy and speed, one may consider surrogate models for real-time simulations (20 to 50 FPS). In this work, we obtained the patient-specific geometry through micro-computed tomography in 8 different configurations, including 15 bio-markers. Assessing the displacement of the bio-markers enabled us to infer the relative strains between the different configurations. A heterogeneous neo-Hookean model was assumed for simulating soft tissue behavior. Based on the displacements and the position of the biomarkers, model parameters identification was performed to calibrate the experimental data with the finite element method results. To overcome speed performance issues, Convolutional Neural Network (CNN) trained with a synthetic simulation-based dataset generated by applying different gravity directions is used. Preliminary results show that CNN can predict the displacement of anatomical landmarks to millimetric precision and is 100 times faster than the finite element method, satisfying our real-time objective. Plus, the use of Bayesian inferences involves a longer prediction time but allows a 95% confidence interval of the biomarkers' displacements. For a given precision, contrary to CNNs, optimization methods are computationally expensive and depend on an initialization point. Although CNNs require new training for each patient, optimization algorithms can be applied regardless of the patient's geometry. Through this study, we observed that material properties were playing an essential role but not as much as the anatomical structures e.g. infra-mammary or Copper’s ligaments. [less ▲]

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See detailUser-centricity and Public Values in eGovernment: Friend or Foe?
Weigl, Linda UL; Amard, Alexandre UL; Marxen, Hanna UL et al

in Proceedings of the 30th European Conference on Information Systems (ECIS) (2022, July)

In their delivery of services, public administrations seek to develop a ‘citizen-centric’ approach. Concomitantly, user-centricity is emerging as a widely accepted construct for Web 3.0 applications ... [more ▼]

In their delivery of services, public administrations seek to develop a ‘citizen-centric’ approach. Concomitantly, user-centricity is emerging as a widely accepted construct for Web 3.0 applications supporting the digital interaction between service providers and recipients. The digitalization of public services can positively impact important public values, such as efficiency and transparency. However, the digital divide highlights that information and communication technologies can simultaneously neglect public needs. This begs the question of whether user-centricity reflects or conflicts with public values. To answer this question, we present a systematic review of existing literature on user-centricity and public values. The contribution of this paper is an extended taxonomy of public values for user-centricity, as well as recommendations for public policy to address conflicts between public values and user-centricity. [less ▲]

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See detailGuidelines for Assessing the Accuracy of Log Message Template Identification Techniques
Khan, Zanis Ali UL; Shin, Donghwan UL; Bianculli, Domenico UL et al

in Proceedings of the 44th International Conference on Software Engineering (ICSE ’22) (2022, July)

Log message template identification aims to convert raw logs containing free-formed log messages into structured logs to be processed by automated log-based analysis, such as anomaly detection and model ... [more ▼]

Log message template identification aims to convert raw logs containing free-formed log messages into structured logs to be processed by automated log-based analysis, such as anomaly detection and model inference. While many techniques have been proposed in the literature, only two recent studies provide a comprehensive evaluation and comparison of the techniques using an established benchmark composed of real-world logs. Nevertheless, we argue that both studies have the following issues: (1) they used different accuracy metrics without comparison between them, (2) some ground-truth (oracle) templates are incorrect, and (3) the accuracy evaluation results do not provide any information regarding incorrectly identified templates. In this paper, we address the above issues by providing three guidelines for assessing the accuracy of log template identification techniques: (1) use appropriate accuracy metrics, (2) perform oracle template correction, and (3) perform analysis of incorrect templates. We then assess the application of such guidelines through a comprehensive evaluation of 14 existing template identification techniques on the established benchmark logs. Results show very different insights than existing studies and in particular a much less optimistic outlook on existing techniques. [less ▲]

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See detailFrom social robots to creative humans and back
Gubenko, Alla UL; Lubart, Todd; Houssemand, Claude UL

in Confalonieri, Roberto; Kutz, Oliver; Veale, Tony (Eds.) et al Proceedings of the Thirteenth International Conference on Computational Creativity (2022, July)

The research on physically and socially situated artificial agents could complement and enrich computational models of creativity. This paper discusses six perspective lines of inquiry at the intersection ... [more ▼]

The research on physically and socially situated artificial agents could complement and enrich computational models of creativity. This paper discusses six perspective lines of inquiry at the intersection of creativity and social robotics. It provides a description of ways in which the field of social robotics may influence (and be influenced by) creativity research in psychology and speculates how human-machine co-creation will affect the notions of both human and artificial creativity. By discussing potential research areas, the authors hope to outline an agenda for future collaboration between creativity scholars in psychology, social robotics, and computer science. [less ▲]

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See detailATUA: an update-driven app testing tool
Ngo, Chanh Duc UL; Pastore, Fabrizio UL; Briand, Lionel UL

in The 31st ACM SIGSOFT International Symposium on Software Testing and Analysis (2022, July)

App testing tools tend to generate thousand test inputs; they help engineers identify crashing conditions but not functional failures. Indeed, detecting functional failures requires the visual inspection ... [more ▼]

App testing tools tend to generate thousand test inputs; they help engineers identify crashing conditions but not functional failures. Indeed, detecting functional failures requires the visual inspection of App outputs, which is infeasible for thousands of inputs. Existing App testing tools ignore that most of the Apps are frequently updated and engineers are mainly interested in testing the updated functionalities; indeed, automated regression test cases can be used otherwise. We present ATUA, an open source tool targeting Android Apps. It achieves high coverage of the updated App code with a small number of test inputs, thus alleviating the test oracle problem (less outputs to inspect). It implements a model-based approach that synthesizes App models with static analysis, integrates a dynamically-refined state abstraction function and combines complementary testing strategies, including (1) coverage of the model structure, (2) coverage of the App code, (3) random exploration, and (4) coverage of dependencies identified through information retrieval. Our empirical evaluation, conducted with nine popular Android Apps (72 versions), has shown that ATUA, compared to state-of-the-art approaches, achieves higher code coverage while producing fewer outputs to be manually inspected. A demo video is available at https://youtu.be/RqQ1z_Nkaqo. [less ▲]

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See detailDeep Learning Based Joint Collision Detection and Spreading Factor Allocation in LoRaWAN
Abd Elkarim, Seham Ibrahem; Elsherbini, M.M.; Mohammed, Ola et al

Poster (2022, July)

Long-range wide area network (LoRaWAN) is a promising low-power network standard that allows for long-distance wireless communication with great power saving. L oRa is based on pure ALOHA protocol for ... [more ▼]

Long-range wide area network (LoRaWAN) is a promising low-power network standard that allows for long-distance wireless communication with great power saving. L oRa is based on pure ALOHA protocol for channel access, which causes collisions for the transmitted packets. The collisions may occur in two scenarios, namely the intra-spreading factor (intra-SF) and the inter-spreading factor (inter-SF) interference. Consequently, the SFs assignment is a very critical task for the network performance. This paper investigates a smart SFs assignment technique to reduce collisions probability and improve the network performance. In this work, we exploit different architectures of artificial neural networks for detecting collisions and selecting the optimal SF. The results show that the investigated technique achieves a higher prediction accuracy than traditional machine learning algorithms and enhances the energy consumption of the network. [less ▲]

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See detailParallel Multi-Physics Simulation of Biomass Furnace and Cloud-based Workflow for SMEs
Besseron, Xavier UL; Rusche, Henrik; Peters, Bernhard UL

in Practice and Experience in Advanced Research Computing (PEARC '22) (2022, July)

Biomass combustion is a well-established process to produce energy that offers a credible alternative to reduce the consumption of fossil fuel. To optimize the process of biomass combustion, numerical ... [more ▼]

Biomass combustion is a well-established process to produce energy that offers a credible alternative to reduce the consumption of fossil fuel. To optimize the process of biomass combustion, numerical simulation is a less expensive and time-effective approach than the experimental method. However, biomass combustion involves intricate physical phenomena that must be modeled (and validated) carefully, in the fuel bed and in the surrounding gas. With this level of complexity, these simulations require the use of High-Performance Computing (HPC) platforms and expertise, which are usually not affordable for manufacturing SMEs. In this work, we developed a parallel simulation tool for the simulation of biomass furnaces that relies on a parallel coupling between Computation Fluid Dynamics (CFD) and Discrete Element Method (DEM). This approach is computation-intensive but provides accurate and detailed results for biomass combustion with a moving fuel bed. Our implementation combines FOAM-extend (for the gas phase) parallelized with MPI, and XDEM (for the solid particles) parallelized with OpenMP, to take advantage of HPC hardware. We also carry out a thorough performance evaluation of our implementation using an industrial biomass furnace setup. Additionally, we present a fully automated workflow that handles all steps from the user input to the analysis of the results. Hundreds of parameters can be modified, including the furnace geometry and fuel settings. The workflow prepares the simulation input, delegates the computing-intensive simulation to an HPC platform, and collects the results. Our solution is integrated into the Digital Marketplace of the CloudiFacturing EU project and is directly available to SMEs via a Cloud portal. As a result, we provide a cutting-edge simulation of a biomass furnace running on HPC. With this tool, we demonstrate how HPC can benefit engineering and manufacturing SMEs, and empower them to compute and solve problems that cannot be tackled without. [less ▲]

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See detailFemmes (monoparentales) en difficultés de logement
Dujardin, Céline UL

Scientific Conference (2022, June 30)

Le projet SOHOME (Social Housing and Homelessness) poursuit des questions de recherché liées aux personnes en difficultés de logement au Luxembourg. Il dresse un état de lieu actuel en explorant les ... [more ▼]

Le projet SOHOME (Social Housing and Homelessness) poursuit des questions de recherché liées aux personnes en difficultés de logement au Luxembourg. Il dresse un état de lieu actuel en explorant les offres d’aide et les pistes de solution dans le champ de l’intervention sociale. Les principales questions de recherche sont les suivantes : (1) Qu’est-ce qui caractérise la population concernée au Luxembourg ? (2) Comment les politiques sociales et le travail social répondent-ils aux enjeux identifiés ? (3) Quels sont les principaux défis du travail social dans le domaine du sans-abrisme et de l’exclusion liée au logement ? Par le biais d’une méthodologie de recherche qualitative, le projet permet de nombreux aperçus dans le champ de l’intervention sociale. La présente communication aborde la problématique des femmes en difficultés de logement qui sont accueillies seules ou avec leurs enfants dans un foyer d’urgence pour femmes. Deux questions précises guident cette partie du projet de recherche : (1) Qu’est-ce qui caractérise les femmes en difficultés de logement au Luxembourg ? (2) Quelles sont les offres d’aide du travail social et les défis rencontrés face aux femmes concernées ? Les femmes touchées par des grandes difficultés liées au logement forment un groupe statistiquement plutôt invisible parce qu’elles cherchent d’autres solutions de logement que l’hébergement en foyer d’urgence (Batista, 2010). Les résultats de notre étude montrent que les femmes encadrées sans enfants arrivent souvent plus rapidement à stabiliser leur situation (cf. Finfgeld-Connett, 2010). Par contre, les femmes de 45 ans et plus ainsi que les femmes avec enfants semblent être les groupes les plus vulnérables pris en charge par les différents foyers d’urgence pour femmes au Luxembourg. La communication abordera les résultats liés aux deux questions ciblées sur les femmes concernées en les mettant en lien avec la politique sociale au Luxembourg. [less ▲]

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See detailMultilevel Access to Justice in Environmental Matters in the European Union: A Systemic Imbalance?
Muñoz, Susana UL

Scientific Conference (2022, June 30)

The European Union (EU) is a Party to the Aarhus Convention, as are, separately, its 27 Member States. The EU’s composite and multi-layered system raises important issues as regards compliance with this ... [more ▼]

The European Union (EU) is a Party to the Aarhus Convention, as are, separately, its 27 Member States. The EU’s composite and multi-layered system raises important issues as regards compliance with this Convention. As a new kind of environment agreement, it grants the public rights and imposes on Parties obligations regarding access to information, public participation, and access to justice in environmental matters – the three pillars of environmental democracy. Access to justice emerges as the primary means for the Convention’s enforcement, supporting the two other pillars’ implementation, and safeguarding the rights it enshrines and those arising from EU or national law. Despite its pivotal importance, there is no common framework for access to environmental justice in the EU. Numerous obstacles remain at various levels. Considerable discrepancies exist between national systems. According to the ACCC, the EU failed to comply with its obligations under the Convention regarding acts and omissions by the EU institutions and bodies that contravene EU environmental law. As part of the European Green Deal, Regulation (EU) 2021/1767 – adopted on 6 October 2021 prior to the opening of the seventh session of the Meeting of the Parties – introduces significant amendments to the Aarhus Regulation which are expected to bring the EU into compliance with the Convention. Building on EU and national case-law and legislation, this paper provides a critical analysis of the amended Regulation and its impact on the implementation of the EU’s multilevel access to justice to protect every person’s right to a healthy environment. [less ▲]

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See detailWhen the “vulnerable” talk back: subjective responses and individual experiences of young refugees
Gilodi, Amalia UL; Richard, Catherine UL

Scientific Conference (2022, June 30)

In the context of international protection and reception, an increasing amount of interest has been given to the assessment of vulnerability among forced migrants in order to provide special provisions ... [more ▼]

In the context of international protection and reception, an increasing amount of interest has been given to the assessment of vulnerability among forced migrants in order to provide special provisions and guarantees to ‘vulnerable refugees’. However, a common definition of vulnerability does not exist. The systematisation of individuals’ experiences in pre-defined bureaucratic categories risks ignoring the contextual and contingent nature of migrants’ vulnerability, the subjective and biographical differences among those considered vulnerable and the agency of each individual facing conditions of vulnerability. Thus, in the context of the H2020 project MIMY, this paper proposes to explore the experiences and feelings of the people living in an apparent condition of vulnerability. Based on in-depth interviews with young adults who obtained refugee status in Luxembourg but still live in ‘temporary’ reception centres, the current study wants to move beyond the bureaucratic vulnerability label, questioning the relationship between structural, contingent and material conditions of vulnerability and the subjective experiences and responses of the active agents who occupy them. Additionally, bringing the stories and perspectives of young refugees living in Luxembourg to the forefront, the study points to the variability of vulnerability at the individual level in the context of integration. We propose to analyse such plurality of stories through the lens of agency and temporality, as the unique product of past personal experiences, current situations of difficulty and conditions of(in)security (based on the interrelationship between obstacles and resources) and individual future perspectives and feelings of self-efficacy. [less ▲]

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See detailwenn Dinge Höflichkeit machen. Materialität der Höflichkeit in der Literatur des Mittelalters
Reicher, Ruth UL

Scientific Conference (2022, June 30)

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See detailLe travail frontalier "à distance" : les enjeux du télétravail et des espaces de coworking dans un espace transfrontalier
Pigeron-Piroth, Isabelle UL; Belkacem, Rachid

Scientific Conference (2022, June 30)

The objective of this paper is to identify the economic and social challenges of telework in the context of a cross-border labor market : Greater Region SaarLorLux, a cross-border area including ... [more ▼]

The objective of this paper is to identify the economic and social challenges of telework in the context of a cross-border labor market : Greater Region SaarLorLux, a cross-border area including Luxembourg, Lorraine (in France), Saarland and Rhineland Palatinate (in Germany) and Wallonia (in Belgium). This area is strongly concerned by the flows of border workers (nearly 260,000 in 2021). Teleworking has been imposed by the pandemic and is not without raising a certain number of questions: legal, social, fiscal.... linked to the presence of the border between the place of residence and the place of work. In a context of mobility and congestion problems, another form of remote work has developed in recent years : coworking spaces. This paper aims to discuss these two organizational modalities of teleworking, but also their challenges for the development of the border territories of both residence and work. [less ▲]

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See detailDemocracy and the digital revolution – steering an evolving paradigm
Danescu, Elena UL

Scientific Conference (2022, June 29)

Knowledge-based societies rely to a large extent on intangible assets and digital technologies, and these are having an increasing impact on information systems, power, governance and citizenship, driven ... [more ▼]

Knowledge-based societies rely to a large extent on intangible assets and digital technologies, and these are having an increasing impact on information systems, power, governance and citizenship, driven by a proliferation of stakeholders and networks at multiple levels (states, international organisations, private companies, civil society and citizens. There is a clear need for international regulation in this area. This paper takes a multidisciplinary approach, combining an examination of theoretical, conceptual and methodological frameworks with an analysis of relevant public and private archives, with a threefold objective: 1) to outline issues and challenges in terms of human rights, freedom and democracy; 2) to identify the regulatory provisions adopted at European and international level to promote accountability, civic engagement and digital literacy through new forms of (mediated) democracy; and 3) to identify future prospects, risks and uncertainties in the era of artificial intelligence. [less ▲]

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See detailWeb archives of the COVID-crisis : challenges related to short-term and long-term readability
Schafer, Valerie UL

Scientific Conference (2022, June 29)

During the COVID-19 crisis many institutions have started live and special collections related to web archives of the pandemic. Many libraries have also been involved in an initiative led by the IIPC ... [more ▼]

During the COVID-19 crisis many institutions have started live and special collections related to web archives of the pandemic. Many libraries have also been involved in an initiative led by the IIPC (International Internet Preservation Consortium) to gather a huge international collection of web archives available through Archive-It. Taking as a starting point two research projects related to the analysis of the web archiving of the COVID crisis, that we conducted within WARCnet and through the AWAC2 cohort program, this presentation will focus on issues related to scalable reading, contextualization of datasets, FAIR data, sustainability, inclusiveness, etc., in order to unfold the challenges of these collections and of their analysis in a short and in a long term perspective. [less ▲]

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See detailDESIGN OF BIOMECHANICAL TESTING DEVICE FOR THE PELVIS INCLUDING GAIT MUSCLE FORCES
Soliman, Ahmed Abdelsalam Mohamed UL; Ricci, Pierre-Louis; Kedziora, Slawomir UL et al

Scientific Conference (2022, June 27)

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See detailTrainees in an EU institution: Getting ready for a multilingual workplace
Lovrits, Veronika UL

Scientific Conference (2022, June 24)

Institutions of the European Union welcome over 2,000 trainees every year (EPSO 2022). What can the young graduates learn about the specifics of language use in a multilingual workplace? To find out, the ... [more ▼]

Institutions of the European Union welcome over 2,000 trainees every year (EPSO 2022). What can the young graduates learn about the specifics of language use in a multilingual workplace? To find out, the present sociolinguistic study interviewed 8 juniors (trainees) and 4 seniors (permanent employees) in a terminology and communication unit in an EU institution in Luxembourg. Qualitative data were collected from September 2020 to May 2021 in a participatory manner (McIntyre 2008), joining the recent interest in folklinguistic empowerment (Rymes 2021). The researcher took part in discussions with participants and encouraged their in-depth reflection on communication in the multilingual workplace. Iterative interviews, viewed as social interaction with critical reflective positioning of the researcher (Deppermann 2013), were accompanied by observation of meetings (online, due to Covid-19 pandemics), reflective drawing of metaphors by participants (Molinié 2009), and written reflections. Participants were free to define what language and multilingualism meant to them, as the study also aimed to avoid implicit methodological nationalism (Kraus 2018). Informed by the results of a pilot study in the same workplace (Lovrits and de Bres 2021), the collected data were subjected to a discursive analysis of stances (Jaffe 2009). Results showed that trainees’ understanding of language competence at work changed over the time. Aligning with stances of their supervisors towards the end of the traineeship stay, the juniors no longer focused on a linguistic standard in everyday communication. Instead, they began to pay more attention to the socio-emotional and relational aspects of their language use. The trainees reconstructed their understanding of (flexible) multilingualism as a basis for personal well-being at work and stopped fixating on formal linguistic "mistakes". Moreover, since research has emphasized socio-pragmatic diversity in the process of meaning making (Verschueren 2000), the seniors recognized the trainees' need to make the pragmatic aspects of everyday multilingualism explicit. This revelation has led to changes in language management in the workplace and has the potential to further inspire lifelong learning and professional development in the changing conditions of the global labour market (Budach and de Saint-Georges 2017). The findings are particularly relevant for professionals who facilitate transitions from monolingual to multilingual environments. The study reveals the importance of metalinguistic awareness in people coming from linguistically homogeneous settings into the so called "post-monolingual conditions" (Yildiz 2012) of an international workplace. [less ▲]

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See detailFrom Graphs to the Science Computer of a Space Telescope. The power of Petri Nets in Systems Engineering
Graczyk, Rafal UL; Bujwan, Waldemar; Darmetko, Marcin et al

in Graczyk, Rafal; Bujwan, Waldemar; Darmetko, Marcin (Eds.) et al From Graphs to the Science Computer of a Space Telescope. The power of Petri Nets in Systems Engineering (2022, June 23)

Space system engineering has to follow a rigorous design process to manage performance/risk trade-offs at each development stage and possibly across several functional and organizational domains. The ... [more ▼]

Space system engineering has to follow a rigorous design process to manage performance/risk trade-offs at each development stage and possibly across several functional and organizational domains. The process is further complicated by the co-development of multiple solutions, each contributing differently to the goal and with different tradeoffs. Moreover, the design process is iterative, involving both changing requirements and specifications along the different ways that lead to the set goal of the mission. The above requires rigorous modeling that, in addition, must be easily extendible and maintainable across organizational units. On the example of the PROBA-3 science computer (instrument control unit, CCB DPU), we show how Petri Nets can serve as such a simple-to-maintain, holistic model, combining finite-state characterizations with dynamic system behavior caused by hardware-software interactions, to express the component-state dependent end-to-end performance characteristics of the system. The paper elaborates on how the proposed Petri-Net modeling scheme allows for system architecture optimization that result in safely reduced technical margins and in turn substantial savings in components costs. We show that performance metrics, obtained from simulation, correlate well with the real performance characteristics of the flight model of PROBA-3's science computer. [less ▲]

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See detailWhich Factors Play a Role in Coco Issuance? Evidence from European Banks.
Wolff, Christian UL

Scientific Conference (2022, June 20)

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See detailBackscatter-Aided NOMA V2X Communication under Channel Estimation Errors
Khan, Wali Ullah UL; Jamshed, Muhammad Ali; Mahmood, Asad UL et al

Scientific Conference (2022, June 20)

Backscatter communications (BC) has emerged as a promising technology for providing low-powered transmissions in nextG (i.e., beyond 5G) wireless networks. The fundamental idea of BC is the possibility of ... [more ▼]

Backscatter communications (BC) has emerged as a promising technology for providing low-powered transmissions in nextG (i.e., beyond 5G) wireless networks. The fundamental idea of BC is the possibility of communications among wireless devices by using the existing ambient radio frequency signals. Non-orthogonal multiple access (NOMA) has recently attracted significant attention due to its high spectral efficiency and massive connectivity. This paper proposes a new optimization framework to minimize total transmit power of BC-NOMA cooperative vehicle-to-everything networks (V2XneT) while ensuring the quality of services. More specifically, the base station (BS) transmits a superimposed signal to its associated roadside units (RSUs) in the first time slot. Then the RSUs transmit the superimposed signal to their serving vehicles in the second time slot exploiting decode and forward protocol. A backscatter device (BD) in the coverage area of RSU also receives the superimposed signal and reflect it towards vehicles by modulating own information. Thus, the objective is to simultaneously optimize the transmit power of BS and RSUs along with reflection coefficient of BDs under perfect and imperfect channel state information. The problem of energy efficiency is formulated as non-convex and coupled on multiple optimization variables which makes it very complex and hard to solve. Therefore, we first transform and decouple the original problem into two sub-problems and then employ iterative sub-gradient method to obtain an efficient solution. Simulation results demonstrate that the proposed BC-NOMA V2XneT provides high energy efficiency than the conventional NOMA V2XneT without BC. [less ▲]

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See detailArea-Power Analysis of FFT Based Digital Beamforming for GEO, MEO, and LEO Scenarios
Palisetty, Rakesh UL; Eappen, Geoffrey UL; Gonzalez Rios, Jorge Luis UL et al

in Area-Power Analysis of FFT Based Digital Beamforming for GEO, MEO, and LEO Scenarios (2022, June 19)

Satellite communication systems can provide seamless wireless coverage directly or through complementary ground terrestrial components and are projected to be incorporated into future wireless networks ... [more ▼]

Satellite communication systems can provide seamless wireless coverage directly or through complementary ground terrestrial components and are projected to be incorporated into future wireless networks, particularly 5G and beyond networks. Increased capacity and flexibility in telecom satellite payloads based on classic radio frequency technology have traditionally translated into increased power consumption and dissipation. Much of the analog hardware in a satellite communications payload can be replaced with highly integrated digital components that are often smaller, lighter, and less expensive, as well as software reprogrammable. Digital beamforming of thousands of beams simultaneously is not practical due to the limited power available onboard satellite processors. Reduced digital beamforming power consumption would enable the deployment of a full digital payload, resulting in comprehensive user applications. Beamforming can be implemented using matrix multiplication, hybrid methodology, or a discrete Fourier transform (DFT). Implementing DFT via fast Fourier transform (FFT) reduces the power consumption, process time, hardware requirements, and chip area. Therefore, in this paper, area-power efficient FFT architectures for digital beamforming are analyzed. The area in terms of look up tables (LUTs) is estimated and compared among conventional FFT, fully unrolled FFT, and a 4-bit quantized twiddle factor (TF) FFT. Further, for the typical satellite scenarios, area, and power estimation are reported. [less ▲]

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See detailWhen RIS Meets GEO Satellite Communications: A New Sustainable Optimization Framework in 6G
Khan, Wali Ullah UL; Lagunas, Eva UL; Mahmood, Asad UL et al

Scientific Conference (2022, June 19)

Reflecting intelligent surfaces (RIS) is a low-cost and energy-efficient solution to achieve high spectral efficiency in sixth-generation (6G) networks. The basic idea of RIS is to smartly reconfigure the ... [more ▼]

Reflecting intelligent surfaces (RIS) is a low-cost and energy-efficient solution to achieve high spectral efficiency in sixth-generation (6G) networks. The basic idea of RIS is to smartly reconfigure the signal propagation by using passive reflecting elements. On the other side, the demand of high throughput geostationary (GEO) satellite communications (SatCom) is rapidly growing to deliver broadband services in inaccessible/insufficient covered areas of terrestrial networks. This paper proposes a GEO SatCom network, where a satellite transmits the signal to a ground mobile terminal using multicarrier communications. To enhance the effective gain, the signal delivery from satellite to the ground mobile terminal is also assisted by RIS which smartly shift the phase of the signal towards ground terminal. We consider that RIS is mounted on a high building and equipped with multiple re-configurable passive elements along with smart controller. We jointly optimize the power allocation and phase shift design to maximize the channel capacity of the system. The joint optimization problem is formulated as nonconvex due to coupled variables which is hard to solve through traditional convex optimization methods. Thus, we propose a new optimal algorithm which is based on Mesh Adaptive Direct Search to obtain an efficient solution. Simulation results unveil the benefits of RIS-assisted SatCom in terms of system channel capacity. [less ▲]

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See detailEmission-aware Resource Optimization Framework for Backscatter-enabled Uplink NOMA Networks
Jamshed, Muhammad Ali; Khan, Wali Ullah UL; Pervaiz, Haris et al

Poster (2022, June 19)

In the last decade, a sharp surge in the number of user proximity wireless devices (UPWDs) has been observed. This has increased the level of electromagnetic field (EMF) exposure of the users ... [more ▼]

In the last decade, a sharp surge in the number of user proximity wireless devices (UPWDs) has been observed. This has increased the level of electromagnetic field (EMF) exposure of the users substantially and hence, the possible physiological effects. Ambient backscatter communications (ABC) has appeared to be a promising solution to reduce the power consumption of UPWDs by converting ambient radio frequency (RF) signals into useful signals while non-orthogonal multiple access (NOMA) is a compelling multiplexing scheme for enhanced spectral efficiency. This paper utilises a novel combination of ABC and NOMA to reduce the EMF in the uplink of wireless communication systems. This contemporary approach of EMF-aware resource optimization is based on k-medoids and Silhouette analysis. To curtail the uplink EMF, a power allocation strategy is also derived by converting a non-convex problem to a convex one and solving accordingly. The numerical results exhibit that the proposed ABC, NOMA, and unsupervised learning based scheme achieves a reduction in the EMF by at least 75% in comparison to the existing solutions. [less ▲]

See detailJewish History and the Politics of Digitisation
Zaagsma, Gerben UL

Scientific Conference (2022, June 17)

Detailed reference viewed: 13 (0 UL)