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See detailCogPonder: Towards a Computational Framework of General Cognitive Control
Ansarinia, Morteza UL; Cardoso-Leite, Pedro UL

Poster (2023, August)

Current computational models of cognitive control exhibit notable limitations. In machine learning, artificial agents are now capable of performing complex tasks but often ignore critical constraints such ... [more ▼]

Current computational models of cognitive control exhibit notable limitations. In machine learning, artificial agents are now capable of performing complex tasks but often ignore critical constraints such as resource limitations and how long it takes for the agent to make decisions and act. Conversely, cognitive control models in psychology are limited in their ability to tackle complex tasks (e.g., play video games) or generalize across a battery of simple cognitive tests. Here we introduce CogPonder, a flexible, differentiable, cognitive control framework that is inspired by the Test-Operate-Test-Exit (TOTE) architecture in psychology and the PonderNet framework in machine learning. CogPonder functionally decouples the act of control from the controlled processes by introducing a controller that acts as a wrapper around any end-to-end deep learning model and decides when to terminate processing and output a response, thus producing both a response and response time. Our experiments show that CogPonder effectively learns from data to generate behavior that closely resembles human responses and response times in two classic cognitive tasks. This work demonstrates the value of this new computational framework and offers promising new research prospects for both psychological and computer sciences. [less ▲]

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See detailA High-Resolution Numerical Weather Prediction Model for Nowcasting Precipitation in the Grand-Duchy of Luxembourg (NWPLux)
Rehman, Haseeb Ur UL

Poster (2023, June)

Compared to alluvial floods, flash or pluvial floods are difficult to predict because they result from intense and brief periods of extreme precipitation. The project NWPLux aims to develop, a high ... [more ▼]

Compared to alluvial floods, flash or pluvial floods are difficult to predict because they result from intense and brief periods of extreme precipitation. The project NWPLux aims to develop, a high-resolution numerical weather prediction (NWP) model for effective local heavy rainfall prediction in a nowcasting scenario and provide real time for flood simulation. Modelling is based on the Weather Research and Forecasting (WRF) model, with a large-eddy simulation (LES) type 3-dimensional cloud model to simulate small-scale, high-intensity convective precipitation. It is the first such dedicated NWP model for Luxembourg and the Greater Region. As part of this project, we will also test run the LISFlood flood model in an operational inundation forecast mode, meaning that the flood model will be run with the WRF precipitation forecasts as inputs. As an initial run the WRF model was setup with two distinct domains, specifically the Greater Region and Luxembourg with respective horizontal grid spacing of 16 km and 4 km, leveraging high resolution static data. Met data from the NCAR RDA dataset ds083.2 was utilized, spanning from July 08, 2021 to July 15, 2021, and was subjected to the "Conus" physics suit. The output interval was one hour. Preliminary results from NWP runs indicated that the higher resolution simulations (4 km) exhibited superior performance when compared to the lower resolution simulations (16 km). Keywords: NWP, WRF, Flash flood, LISFlood, cloud modelling [less ▲]

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See detailInitial Orbit Determination Results from the University of Luxembourg using Spire GNSS Tracking Data
Shafiei, Parisa UL; Bemtgen, Jean UL; Talpe, Matthieu et al

Poster (2023, April 28)

CubeSats constellations using commercial off-the-shelf components have been studied for different applications, such as GNSS Radio Occultation (GNSS-RO). Furthermore, precise orbit determination of Low ... [more ▼]

CubeSats constellations using commercial off-the-shelf components have been studied for different applications, such as GNSS Radio Occultation (GNSS-RO). Furthermore, precise orbit determination of Low Earth Orbit (LEO) CubeSats based on multiple GNSS constellations would open new opportunities for scientific applications such as Earth’s gravity field measurements. In GNSS kinematic orbit determination, which is the common method used for small sats, the derived orbits are affected by noise, data gaps, outliers, measurement errors as well as poor geometry of the observations. Our work seeks to mitigate these issues and we present two areas of research: 1) GNSS network processing of GPS and Galileo constellations and 2) kinematic orbit determination of a set of Spire CubeSats that host a GNSS-RO payload. An initial architecture of kinematic orbit processing for the Spire GNSS-RO CubeSats constellation is obtained and the details on validations and limitations are discussed in more details. In addition, we showcase the agreement between the GNSS orbit products produced at the University of Luxembourg (UL) with those of the Center for Orbit Determination in Europe (CODE). Finally, the Spire kinematic orbits based on the raw observation approach are derived and compared to the L1B Spire orbit products. [less ▲]

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See detailThe Ugly Truth of Realistic Perception in Vehicular Simulations
Hawlader, Faisal UL; Frank, Raphaël UL

Poster (2023, January 08)

Automated vehicles use sensors to perceive the environment, and studies have shown the limitations of these sensors. The onboard sensors may not detect objects when other participants occlude the Field of ... [more ▼]

Automated vehicles use sensors to perceive the environment, and studies have shown the limitations of these sensors. The onboard sensors may not detect objects when other participants occlude the Field of View (FoV). Thus, sensor efficiency must be tested to ensure its reliability. Simulation is an excellent test option due to the complexity associated with practical experiments. However, emerging simulation frameworks still have various limitations, especially when it comes to large-scale evaluation. This work investigates realistic perception simulation options for autonomous vehicles. We report the perception accuracy for different traffic scenarios. [less ▲]

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See detailHybrid Active-Passive Reconfigurable IntelligentSurface-Assisted UAV Communications
Nguyen, Nhan T.; Nguyen, V.-Dinh; Wu, Qingqing et al

Poster (2022, December)

We consider a novel hybrid active-passive reconfigurable intelligent surface (RIS)-assisted unmanned aerial vehicle (UAV) air-ground communications system. Unlike the conventional passive RIS, the hybrid ... [more ▼]

We consider a novel hybrid active-passive reconfigurable intelligent surface (RIS)-assisted unmanned aerial vehicle (UAV) air-ground communications system. Unlike the conventional passive RIS, the hybrid RIS is equipped with a few active elements to not only reflect but also amplify the incident signals for significant performance improvement. Towards a fairness design, our goal is to maximize the minimum rate among users through jointly optimizing the location and power allocation of the UAV and the RIS reflecting/amplifying coefficients. The formulated optimization problem is nonconvex and challenging, which is efficiently solved via block coordinate descend and successive convex approximation. Our numerical results show that a hybrid RIS requires only 4 active elements and a power budget of 0 dBm to achieve an improvement of 52.08% in the minimum rate, while that achieved by a conventional passive RIS with the same total number of elements is only 18.06%. [less ▲]

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See detailGender and diversity representations in textbooks in Luxembourgish secondary education.
Kerger, Sylvie UL; Pianaro, Enrica UL; Schadeck, Claire UL

Poster (2022, November 10)

Teaching materials, and particularly textbooks, play an essential role in the socialisation of children through the communication of values. As „textbooks are not a reflection of reality, but an ... [more ▼]

Teaching materials, and particularly textbooks, play an essential role in the socialisation of children through the communication of values. As „textbooks are not a reflection of reality, but an arrangement of the representation of a society that they legitimise” (Brugeilles & Cromer, 2008, p.42), we argue that they contribute to challenging, perpetuating, or increasing gender inequalities. The results of our first study on Luxemburgish primary school textbooks, already published, indicate an androcentric view (Kerger & Brasseur, 2021). In every textbook, we counted more male than female characters in the texts and the illustrations. Men are more often represented in professional activities, while women are more likely to perform domestic activities. The celebrities represented are more often men than women. This poster presents the results of history textbooks in secondary school. It shows an ethnocentric perspective on the representation of non-white characters and those with disabilities. People with disabilities are almost exclusively portrayed when disability as a subject is being discussed. Use of racist language. These representations do not transmit the realities of societal complexities and they contribute to the marginalization and discrimination of non-white people and people with disabilities. [less ▲]

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See detailDo your magic, Harry Potter! popular fiction books and their impact on students’ reading performances
Krämer, Charlotte UL; Rathmacher, Yannick UL; Ottenbacher, Martha UL et al

Poster (2022, November 10)

Previous surveys on the reading habits of Luxembourgish secondary school students (conducted within the framework of the national school monitoring programme Épreuves Standardisées (ÉpStan) in 2016 and ... [more ▼]

Previous surveys on the reading habits of Luxembourgish secondary school students (conducted within the framework of the national school monitoring programme Épreuves Standardisées (ÉpStan) in 2016 and 2019) revealed better reading comprehension results in French and German for those students who frequently read printed narrative texts in their leisure time. However, these studies only focused on different reading modes and text types. They did not investigate which digital and/or printed books students actually read for pleasure, nor which text features determine the positive impact narrative texts have on their reading performances: Is it, for example, the language quality, the richness and complexity of content, or simply the amount of written language they need to process? Therefore, we conducted an explorative follow-up survey within the framework of ÉpStan 2020 and asked secondary school students (Grade 7: n=3055; Grade 9: n=5781) to indicate up to three book titles – printed and e-books respectively – they had read in their leisure time. Despite the omnipresence of digital media, preliminary findings show that both age groups prefer paper-based reading activities when reading longer texts (or books) for pleasure. Nevertheless, the most popular text types and book titles are the same for printed books and e-books: Among them, we find the novel series “Harry Potter”, the rather comic-like book series “Gregs Tagebuch”, and the mangas from the “Naruto”/“Boruto” series. The linkage between students’ leisure time reading activities and their ÉpStan reading performances will be drawn, and some first linguistic text analyses of extracts from the most popular book titles will be conducted in order to reveal some of the text features that foster reading comprehension skills. [less ▲]

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See detailWhat Primary Schools Are Doing Right: Educational Value-Added in Luxembourg
Emslander, Valentin UL; Levy, Jessica UL; Fischbach, Antoine UL

Poster (2022, November 10)

In such a diverse context as Luxembourg, educational inequalities can arise from diverse languages spoken at home, a migration background, or a family’s socioeconomic status. This diversity leads to ... [more ▼]

In such a diverse context as Luxembourg, educational inequalities can arise from diverse languages spoken at home, a migration background, or a family’s socioeconomic status. This diversity leads to different preconditions for learning math and languages (e.g. the language of instruction) and thus shapes the school careers of students (Hadjar & Backes, 2021). The aim of the project Systematic Identification of High Value-Added in Educational Contexts (SIVA) was to answer the questions (1) what highly effective schools are doing “right” or differently and (2) what other schools can learn from them in alleviating inequalities. In collaboration with the Observatoire National de la Qualité Scolaire, we investigated the differences of schools with stable high value-added (VA) scores to those with stable medium or low VA scores from multiple perspectives. VA is a statistical regression method usually used to fairly estimate schools’ effectiveness considering diverse student backgrounds. First, we identified 16 schools which had a stable high, medium, or low VA scores over two years. Second, we collected data on their pedagogical strategies, student background, and school climate through questionnaires and classroom observations. Third, we matched our data to results from the Luxembourg School Monitoring Programme ÉpStan (LUCET, 2021). We selected the variables based on learning models focusing on aspects such as school organization or classroom management (e.g., Hattie, 2008; Helmke et al., 2008; Klieme et al., 2001). We further investigated specificities about the Luxembourgish school system, which are not represented in international school learning models (such as the division into two-year learning cycles, the multilingual school setting, or the diverse student population). We will discuss the SIVA-project, its goals, and its data collection leading to data from observations in 49 classroom and questionnaires with over 500 second graders, their parents, their teachers, as well as school presidents and regional directors. Literature Hadjar, A., & Backes, S. (2021). Bildungsungleichheiten am Übergang in die Sekundarschule in Luxemburg. https://doi.org/10.48746/BB2021LU-DE-21A Hattie, J. (2008). Visible Learning: A synthesis of over 800 meta-analyses relating to achievement (0 ed.). Routledge. https://doi.org/10.4324/9780203887332 Helmke, A., Rindermann, H., & Schrader, F.-W. (2008). Wirkfaktoren akademischer Leistungen in Schule und Hochschule [Determinants of academic achievement in school and university]. In M. Schneider & M. Hasselhorn (Eds.), Handbuch der pädagogischen Psychologie (Vol. 10, pp. 145–155). Hogrefe. Klieme, E., Schümer, G., & Knoll, S. (2001). Mathematikunterricht in der Sekundarstufe I: “Aufgabenkultur” und Unterrichtsgestaltung. TIMSS - Impulse für Schule und Unterricht, 43–57. LUCET. (2021). Épreuves Standardisées (ÉpStan). https://epstan.lu [less ▲]

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See detailEarly Childhood Education and Care in Luxembourg - Is attendance influenced by immigration background and socioeconomic status?
Kaufmann, Lena Maria UL; Fischbach, Antoine UL; Ottenbacher, Martha UL et al

Poster (2022, November 10)

For decades, researchers have been raising awareness of the issue of educational inequalities in the multilingual Luxemburgish school system. Especially children from families with a migration background ... [more ▼]

For decades, researchers have been raising awareness of the issue of educational inequalities in the multilingual Luxemburgish school system. Especially children from families with a migration background or a lower socio-economic status show large deficits in their language and mathematics competences in comparison to their peers. The same applies to children who do not speak Luxemburgish or German as their first language (Hornung et al., 2021; Sonnleitner et al., 2021). One way to reduce such educational inequalities might be an early and extensive participation in early childhood education and care (ECEC). Indeed, participation in ECEC was found to be positively connected to language and cognitive development in other countries, especially for children from disadvantaged families (Bennett, 2012). However, these children attend ECEC less often (Vandenbroeck & Lazzari, 2014). There are indications that lower parental costs might go hand in hand with a greater attendance of ECEC in general (for a Luxembourgish study, see Bousselin, 2019) and in particular by disadvantaged families (Busse & Gathmann, 2020). The aim of this study is to spotlight the attendance of ECEC in Luxembourg during the implementation of the ECEC reform after 2017 which increased free ECEC hours for all families from 3 to 20 hours a week. We draw on a large dataset of about 35.000 children from the Épreuves Standardisées (ÉpStan, the Luxemburg school monitoring programme) from 2015 to 2021 and investigate which children attend any kind of regulated ECEC service (public, private or family daycare) in which intensity, taking socio-economic and cultural family factors into account. The findings might help to understand in which contexts ECEC attendance should be further encouraged. Implications for future policy decisions are discussed with the goal of further promoting equal educational opportunities for all children. [less ▲]

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See detailIntegration of backscatter communication with multi-cell NOMA: a spectral efficiency optimization under imperfect SIC
Khan, Wali Ullah UL; Lagunas, Eva UL; Mahmood, Asad UL et al

Poster (2022, November 03)

Future wireless networks are expected to connect large-scale low-powered communication devices using the available spectrum resources. Backscatter communications (BC) is an emerging technology towards ... [more ▼]

Future wireless networks are expected to connect large-scale low-powered communication devices using the available spectrum resources. Backscatter communications (BC) is an emerging technology towards battery-free transmission in future wireless networks by leveraging ambient radio frequency (RF) waves that enable communications among wireless devices. Non-orthogonal multiple access (NOMA) has recently drawn significant attention due to its high spectral efficiency. The combination of these two technologies can play an important role in the development of future networks. This paper proposes a new optimization approach to enhance the spectral efficiency of nonorthogonal multiple access (NOMA)-BC network. Our framework simultaneously optimizes the power allocation of base station and reflection coefficient (RC) of the backscatter device in each cell under the assumption of imperfect signal decoding. The problem of spectral efficiency maximization is coupled on power and RC which is challenging to solve. To make this problem tractable, we first decouple it into two subproblems and then apply the decomposition method and Karush-Kuhn-Tucker conditions to obtain the efficient solution. Numerical results show the performance of the proposed NOMA-BC network over the pure NOMA network without BC. [less ▲]

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See detailBiomechanische Untersuchung zu verschiedenen Verfahren der Stabilisierung von Insuffizienzfrakturen des vorderen Beckenringes
Gerich, Torsten; Soliman, Ahmed Abdelsalam Mohamed UL; Ricci, Pierre-Louis et al

Poster (2022, October 26)

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See detailImproving Machine Learning-based Prediction of Frailty in Elderly People with Digital Wearables : Data from the Berlin Aging Study II (BASE-II)
Didier, Jeff UL; de Landtsheer, Sébastien UL; Pires Pacheco, Maria Irene UL et al

Poster (2022, October 26)

Frailty is a geriatric medical condition that is highly associated with age and age-related diseases. The multidimensional consequences of frailty are heavily impacting the quality of life, and will ... [more ▼]

Frailty is a geriatric medical condition that is highly associated with age and age-related diseases. The multidimensional consequences of frailty are heavily impacting the quality of life, and will inevitably increase the burden on healthcare systems in the future. Most importantly, the lack of a universal standard to describe, diagnose, or let alone treat frailty, is further complicating the situation in the long-term. Nowadays, more and more frailty assessment tools are being developed on a regional and institutional basis, which is continuing to drive the heterogeneity in the characterization of frailty further apart. Gaining better insights into the underlying causes and pathophysiology of frailty, and how it is developing in patients is, therefore, required to establish strong and accurately tailored response schemes for frail patients, where currently only symptoms are treated. Thus, in this study, we deployed machine learning-based classification and optimization techniques to predict frailty in elderly people aged 65 or above from the Berlin Aging Study II (BASE-II, n=1512, frail=484) and revealed some of the most informative biomedical information to characterize frailty, including new potential biomarkers. Frailty in BASE-II was measured by the Fried et al. 5-item frailty index, composed of the clinical variables grip strength, weight loss, exhaustion, physical activity, and gait. The level of frailty in BASE-II was adapted for binary classification purposes by merging the pre-frail and frail levels as frail. A configurable in-house pipeline was developed for pre-processing the clinical data and predicting the target disease by deploying Support Vector Machines Classification. The most informative and essential subgroup of clinical measurements with regards to frailty was investigated by re-optimizing an initially full data-driven model by sequentially leaving out one subgroup. The best prediction power was yielded with resampling and dimensionality reduction techniques using the F-beta-2 score, and was further improved by adding one item of the Fried et al. frailty index. Furthermore, differences between the gender in the data set led to the investigation of gender-specific model configurations, followed by re-optimizations. As a result, we were able to specifically increase the predictive power in gender-specific groups, and will simultaneously emphasize on the differences between the most informative clinical biomarkers as well as the most essential subgroups for mixed and gender-specific BASE-II. The results herein suggest that a combination of the detected easy-to-obtain biomedical information on frailty risk factors together with one Fried et al. phenotype information provided by i.e., smart wearable devices (gait, grip strength, …) could significantly improve the frailty prediction power in mixed and gender-specific clinical cohort data. [less ▲]

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See detailMachine learning-based prediction of frailty in elderly people : Data from the Berlin Aging Study II (BASE-II)
Didier, Jeff UL; de Landtsheer, Sébastien UL; Pires Pacheco, Maria Irene UL et al

Poster (2022, October 09)

Frailty is a geriatric medical condition that is highly associated with age and age-related diseases. The multidimensional consequences of frailty are heavily impacting the quality of life, and will ... [more ▼]

Frailty is a geriatric medical condition that is highly associated with age and age-related diseases. The multidimensional consequences of frailty are heavily impacting the quality of life, and will inevitably increase the burden on healthcare systems in the future. Most importantly, the lack of a universal standard to describe, diagnose, or let alone treat frailty, is further complicating the situation in the long-term. Nowadays, more and more frailty assessment tools are being developed on a regional and institutional basis, which is continuing to drive the heterogeneity in the characterization of frailty further apart. Gaining better insights into the underlying causes and pathophysiology of frailty, and how it is developing in patients is, therefore, required to establish strong and accurately tailored response schemes for frail patients, where currently only symptoms are treated. Thus, in this study, we deployed machine learning-based classification and optimization techniques to predict frailty in the Berlin Aging Study II (BASE-II, N=1512, frail=484) and revealed some of the most informative biomedical information to characterize frailty, including new potential biomarkers. Frailty in BASE-II was measured by the Fried et al. 5-item frailty index, composed of the clinical variables grip strength, weight loss, exhaustion, physical activity, and gait. The level of frailty in BASE-II was adapted for binary classification purposes by merging the pre-frail and frail levels as frail. A configurable in-house pipeline was developed for pre-processing the clinical data, predicting the target disease, and determining the most informative subgroup of clinical measurements with regards to frailty. The best prediction power was yielded with resampling and dimensionality reduction techniques using the F-beta-2 score, and was further increased by adding one item of the Fried et al. frailty index. We suggest that a combination of the easy-to-obtain biomedical information on frailty risk factors together with one Fried et al. phenotype information provided by i.e. smart wearable devices (gait, grip strength, . . . ) could significantly improve the frailty prediction power. [less ▲]

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See detailSMASCH: Facilitating multi-appointment scheduling in longitudinal clinical research studies and care programs
Vega Moreno, Carlos Gonzalo UL; Gawron, Piotr UL; Lebioda, Jacek et al

Poster (2022, September 20)

Longitudinal clinical research studies require conducting various assessments over long periods of time. Such assessments comprise numerous stages, requiring different resources defined by ... [more ▼]

Longitudinal clinical research studies require conducting various assessments over long periods of time. Such assessments comprise numerous stages, requiring different resources defined by multidisciplinary research staff and aligned with available infrastructure and equipment, altogether constrained by time. While it is possible to manage the allocation of resources manually, it is complex and error-prone. Efficient multi-appointment scheduling is essential to assist clinical teams, ensuring high participant retention and producing successful clinical studies, directly impacting patient throughput and satisfaction. We present Smart Scheduling (SMASCH) system [1], a web application for multi-appointment scheduling management aiming to reduce times, optimise resources and secure personal identifiable information. SMASCH facilitates clinical research and integrated care programs in Luxembourg, providing features to better manage multi-appointment scheduling problems (MASPs) characteristic of longitudinal clinical research studies and speed up management tasks. It is present in multiple clinical research and integrated care programs in Luxembourg since 2017, including Dementia Prevention Program, the study for Mild Cognitive Impairment and gut microbiome, and the National Centre of Excellence in Research on Parkinson’s disease [2] which encompasses the study for REM sleep behaviour disorder and the Luxembourg Parkinson’s Study. SMASCH is a free and open-source solution available both as a Linux package and Docker image. [less ▲]

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See detailMachine learning applied to higher order functional representations of omics data reveals biological pathways associated with Parkinson‘s Disease
Gómez de Lope, Elisa UL; Glaab, Enrico UL

Poster (2022, September 18)

Background: Despite the increasing prevalence of Parkinson’s Disease (PD) and research efforts to understand its underlying molecular pathogenesis, early diagnosis of PD remains a challenge. Machine ... [more ▼]

Background: Despite the increasing prevalence of Parkinson’s Disease (PD) and research efforts to understand its underlying molecular pathogenesis, early diagnosis of PD remains a challenge. Machine learning analysis of blood-based omics data is a promising non-invasive approach to finding molecular fingerprints associated with PD that may enable an early and accurate diagnosis. Description: We applied several machine learning classification methods to public omics data from PD case/control studies. We used aggregation statistics and Pathifier’s pathway deregulation scores to generate higher order functional representations of the data such as pathway-level features. The models’ performance and most relevant predictive features were compared with individual feature level predictors. The resulting diagnostic models from individual features and Pathifier’s pathway deregulation scores achieve significant Area Under the Curve (AUC, a receiver operating characteristic curve) scores for both cross-validation and external testing. Furthermore, we identify plausible biological pathways associated with PD diagnosis. Conclusions: We have successfully built machine learning models at pathway-level and single-feature level to study blood-based omics data for PD diagnosis. Plausible biological pathway associations were identified. Furthermore, we show that pathway deregulation scores can serve as robust and biologically interpretable predictors for PD. [less ▲]

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See detailAutomatic Classification of Peer Review Recommendation
Kozlowski, Diego UL; Boothby, Clara; Pei-Ying, Chen et al

Poster (2022, September 08)

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See detailNon-Local Polarizability Density and DFT
Goger, Szabolcs UL; Szabo, Peter UL; Fedorov, Dmitry UL et al

Poster (2022, August 23)

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See detailPoster: Art Installation “Mirror, Mirror” featuring Deepfake and Neural Style Transfer Technologies
Vanden Berghe, Anastasia UL; Fathi, Fatima Zahra UL

Poster (2022, August 15)

The robotic art installation “Mirror, Mirror” is a result of a creative collaboration between an artist and an engineer. The aim of this project is to transform a person’s image and background in order to ... [more ▼]

The robotic art installation “Mirror, Mirror” is a result of a creative collaboration between an artist and an engineer. The aim of this project is to transform a person’s image and background in order to prompt them to examine their version of self and the surrounding reality and make them aware of the developments in the field of social robotics and Artificial Intelligence. [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 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 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 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 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 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 ▲]

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See detailMixed RIS-Relay NOMA-Based RF-UOWC systems
Elsayed, Mohamed; Samir, Ahmed; El-Banna, Ahmad A.Aziz et al

Poster (2022, June)

Reconfigurable intelligent surface (RIS), nonorthogonal multiple access (NOMA), and underwater optical wireless communication (UOWC) are paradigms of technologies that drive the development of ... [more ▼]

Reconfigurable intelligent surface (RIS), nonorthogonal multiple access (NOMA), and underwater optical wireless communication (UOWC) are paradigms of technologies that drive the development of communications nowadays. In this paper, we investigate the performance of a NOMA-based RISassisted hybrid radio frequency (RF)-UOWC system. Due to the interruption of the direct link between the base station and the ship floating on the surface of the water, communication will be carried out via an RIS fixed to an intermediate building. The ship works as a relay that redirects the received signal to two underwater destinations simultaneously. In this paper, we provide new analytical expressions for the outage probability (OP), asymptotic analyses of the OP, and diversity order (D) to gain insights into the system performance. The results showed that the diversity order depends on the UOWC receiver detection technique. In the end, we illustrated that the NOMA-based RISassisted system significantly improves the outage performance of hybrid RF-UWOC systems over a benchmark systems. [less ▲]

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See detailMATERIAL MODELLING AND FINITE ELEMENT ANALYSIS IN METAL ADDITIVE MANUFACTURING
Mashhood, Muhammad UL; Baroli, Davide; Wyart, Eric et al

Poster (2022, May 31)

The additive manufacturing (AM) is competent method for the manufacturing of complex metal parts with wider process flexibility. During manufacturing, the metal part repetitively undergoes heating and ... [more ▼]

The additive manufacturing (AM) is competent method for the manufacturing of complex metal parts with wider process flexibility. During manufacturing, the metal part repetitively undergoes heating and cooling under the influence of laser passes and ambient conditions respectively. In turn, the material experiences the thermal strain and residual stress. The aim of the work is to predict them using certain material model. Where the solidified metal part from melt-pool is considered in current analysis. For numerical simulation, Finite Element Method (FEM) is chosen. The heat equation is first solved for thermal profile of AM Process. Afterwards, the structural analysis is performed with such thermal load. The non linear constitutive material model is utilised. For concerned material model, the temperature dependence upon the material properties is also implemented. The resulting Finite Element Analysis (FEA) platform offers the macro-scale thermal solution and the prediction of resulting plastic distortion in material. This prediction however has become more accurate when the variable material property, depending upon the temperature of analysis zone, is introduced. [less ▲]

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See detailCFD-DEM simulation of melt pool formation and evolution in powder bed fusion process
Aminnia, Navid UL; Estupinan Donoso, Alvaro Antonio UL; Peters, Bernhard UL

Poster (2022, May 31)

Computational models can be used to optimize metal additive manufacturing parts, and can also play a role in the evaluation of component quality. Among the most important components of such models will be ... [more ▼]

Computational models can be used to optimize metal additive manufacturing parts, and can also play a role in the evaluation of component quality. Among the most important components of such models will be the detailed simulation of flow and heat transfer in and around the melt pool that is formed when the powder bed is melted. In the present work, A Powder Bed Fusion process is studied numerically by using a coupled Computational Fluid Dynamics (CFD) model and eXtended Discrete Element Method (XDEM) model to predict the physical behavior of discrete particles and the melt pool. In XDEM, a randomly packed powder bed of spherical particles is generated and heat and momentum exchange of each particle with other particles and the melt pool are calculated. The CFD model will predict the effects of laser-melt and powder-melt interactions on the melt pool dynamics. Using the developed numerical framework, it will be possible to determine how powder size distribution, the velocity of a laser beam, and the power, among other factors, will affect the characteristics of melt pool. [less ▲]

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See detailExploring NVIDIA Omniverse for Future Space Resources Missions
Li, Xiao UL; Yalcin, Baris Can UL; Christidi-Loumpasefski, Olga-Orsalia UL et al

Poster (2022, May 03)

The resources of space offer a means to enable sustainable exploration of the Moon and Solar System beyond, thus developing space resource technologies is becoming a major topic for space-related activity ... [more ▼]

The resources of space offer a means to enable sustainable exploration of the Moon and Solar System beyond, thus developing space resource technologies is becoming a major topic for space-related activity internationally. However, verifying and validating such systems on Earth conditions is challenging due to the difficulty of filling the sim2reality gap by creating the exact environment. We hypothesize that having on-ground experimental facilities that integrate high-fidelity simulation and physical systems will enable close-to-real testing, speeding up the transition between space technology development and deployment stages. NVIDIA Omniverse recently gained interest to create photorealistic environments, and it is a promising tool to simulate space-related scenarios with high fidelity. Physically accurate and faithful on-orbit scenarios could be generated in Omniverse Create by integrating PhysX physics core and Pixar Universal Scene Description. Omniverse also includes a robotic simulator that connects to physical robotic systems. Various connectors between Omniverse and other platforms such as Unreal Engine, Blender, Autodesk, ParaView, and online collaboration capacity offer the possibility of importing models of space mission components, space scenes, and scientific data into Omniverse. NVIDIA Omniverse seems auspicious in terms of developing high-fidelity photorealistic simulations. In the HELEN project between SpaceR and Spacety, we are developing a close-to-real testing environment for validating debris removal technology. Within this project, we will explore the potential of Omniverse to integrate virtual and physical components, i.e., high-fidelity photorealistic on-orbit simulations with the Zero-G lab facility, for creating reliable testing conditions to reduce the sim2reality gap. SIL and HIL testing architectures for space systems will be developed using software such as MATLAB/Simulink. Moreover, the robotic systems of the Zero-G lab can be linked to the Omniverse’s robotic simulator using its ROS & ROS2 bridge. The figure presents an overview of Omniverse under the scope of the HELEN project. HELEN will show the combination of photorealistic simulations using Omniverse, SIL, and HIL with the Zero-G lab creates a high-fidelity testing environment for future space resources technology. We also believe that the number of human-made objects orbiting the Earth constitutes a great potential for the recovery of their resources. Most of those include valuable materials (Aluminum, Gold, Silver). Therefore, in the future, debris mitigation efforts can target the recovery of such resources, as pointed out in [1]. Reference:[1] Frank Koch, The Value of Space Debris (2021), 8th European Conference on Space Debris [less ▲]

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See detailThe Best Space Resource is the One You Can Catch and Reuse
Hubert Delisle, Maxime UL; Yalcin, Baris Can UL; Martinez Luna, Carol UL et al

Poster (2022, May 03)

From the beginning of space exploration more than 60 years ago, only a few in-orbit objects have been removed or reused. In fact, the Kessler Syndrome states that the number of space debris is growing ... [more ▼]

From the beginning of space exploration more than 60 years ago, only a few in-orbit objects have been removed or reused. In fact, the Kessler Syndrome states that the number of space debris is growing exponentially [1], leaving unused uncooperative objects orbiting at high velocities at several altitudes, especially in Low-Earth Orbit (LEO). In other words, the situation brings up two main critical issues: not only a non-sustainable space environment for satellite missions, with orbit saturation, but also the creation of an unsafe place for future human-related space exploration missions. Active Debris Removal is a possible solution for tackling the problem of space debris. Despite being extremely challenging, catching autonomously and harmlessly an uncooperative object tumbling at high velocity demands reliability, compliance and robustness. The fruitful collaboration between industry and academia (Spacety Luxembourg - SnT-SpaceR research group at the University of Luxembourg), is leading to the cutting-edge concept of a two-step capturing mechanism. A first ‘soft capture’ ensures that the debris is received softly while dampening any vibrations generated during the contact. Then, a ‘hard capture’ secures the debris so that it would be deorbited or safely shipped for other orbits or space stations for reuse. Capturing debris and decommissioned in-orbit objects for recycling or reusing can be the anchor of new opportunities in space and beyond. Most of the objects in orbit can have aluminum parts, besides other beneficial materials among their subsystems, such as solar panels, antennas or electronics which can be reused. To maximize space resources reusability, it is important to not harm the target. Capturing solutions such as harpoons or rigid interfaces can cause damage to the targets, resulting in hardly exploitable resources, and even more smaller debris tumbling in orbit [2]. An application of the proposed capturing technology would be to collect defunct satellites and debris, thus contributing to a more sustainable environment in space, gathering those on a possible recycling orbit or to any future Space Station for recycling. References [1] Drmola J. and Hubik T., Kessler Syndrome: System Dynamics Model (2018), In-Space Policy, 44–45, 29–39 [2] Zhao P., Liu J. and Wu C., Survey on Research and Development of On-Orbit Active Debris Removal Methods (2020), Sci China Tech Sci, 63: 2188–2210 [less ▲]

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See detailDownlink Throughput of Cell-Free Massive MIMO Systems Assisted by Hybrid Relay-Reflecting Intelligent Surfaces
Nguyen, Nhan T.; Nguyen, V.-Dinh; Nguyen, Hieu V. et al

Poster (2022, May)

We consider in this work a cell-free (CF) massive multiple-input-multiple-output (mMIMO) system where multiple hybrid relay-reflecting intelligent surfaces (HR-RIS) are deployed to assist communication ... [more ▼]

We consider in this work a cell-free (CF) massive multiple-input-multiple-output (mMIMO) system where multiple hybrid relay-reflecting intelligent surfaces (HR-RIS) are deployed to assist communication between access points and users. We first present the signal model and derive the minimum-mean-square-error estimate of the effective channels. We then present a comprehensive analysis for the considered HR-RIS-aided CF mMIMO system, where the closed-form expression of the downlink throughput is derived. The presented analytical results are also valid for conventional CF mMIMO systems, i.e., CF mMIMO systems with and without passive reconfigurable intelligent surfaces. Finally, the analytical derivations are verified by extensive numerical results. [less ▲]

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See detailA Collaborative System of Flying and Ground Robots with Universal Physical Coupling Interface (PCI), and the Potential Interactive Applications
Wang, Ziming UL; Hu, Ziyi; Man, Yemao et al

Poster (2022, April 28)

Flying and ground robots complement each other in terms of their advantages and disadvantages. We propose a collaborative system combining flying and ground robots, using a universal physical coupling ... [more ▼]

Flying and ground robots complement each other in terms of their advantages and disadvantages. We propose a collaborative system combining flying and ground robots, using a universal physical coupling interface (PCI) that allows for momentary connections and disconnections between multiple robots/devices. The proposed system may better utilize the complementary advantages of both flying and ground robots. We also describe various potential scenarios where such a system could be of benefit to interact with humans - namely, remote field works and rescue missions, transportation, healthcare, and education. Finally, we discuss the opportunities and challenges of such systems and consider deeper questions which should be studied in future work. [less ▲]

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See detailIndividual factors and beliefs determining COVID-19 vaccination willingness
Pauly, Laure UL; Paccoud, Ivana UL; Satagopam, Venkata UL et al

Poster (2022, April)

Background: High vaccination coverage rates are necessary to reduce infections and transmissions of the SARS-CoV-2 virus causing COVID-19 and to allow successful mitigation of the current pandemic. To ... [more ▼]

Background: High vaccination coverage rates are necessary to reduce infections and transmissions of the SARS-CoV-2 virus causing COVID-19 and to allow successful mitigation of the current pandemic. To date, we are still lacking information to explain the hesitancy in Luxembourg towards uptake of the available COVID-19 vaccines. The present study explored motivations for and against vaccination in a population-representative sample of residents across Luxembourg to identify hesitant groups and develop strategies to increase population immunity against SARS-CoV-2. Methods: In the framework of the nationwide, representative longitudinal CON-VINCE study, a sample of 1589 respondents (49.6% women, 84.3% Luxembourg nationality) ranging from 18-84 years, participated in the survey in spring 2021. The protocol of the CON-VINCE study has been described in detail elsewhere (Snoeck et al. 2020). Results: 52% of the respondents had at least partial vaccination at time of assessment between April to June 2021. The most common reasons for vaccination of those willing to be vaccinated (81.2%) were altruistic motivations. Prevalent reasons against vaccination for those undecided (8.7%) or reluctant (10.2%) to be vaccinated were that the vaccine had not been tested sufficiently and the fear of long-term vaccine side effects. Only very few of the vaccination-hesitant or -reluctant respondents reported that they did not believe in vaccination in general. Conclusion: The present study identified motivations for and against COVID-19 vaccination and determined demographic and socio-economic factors associated with vaccination willingness. To increase vaccination rates, public health communication needs to target those unsure or unwilling to be vaccinated. We will continue to study the vaccination uptake in the Luxembourg population, as CON-VINCE is now part of the H2020-funded international ORCHESTRA project (https://orchestra-cohort.eu), research into comparing these results on a Pan-European level. [less ▲]

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See detailRetrograde Procedural Memory in Parkinson's Disease
Pauly, Laure UL; Pauly, Claire UL; Hansen, Maxime UL et al

Poster (2022, March)

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See detailWaveform Design for Joint Radar-Communications with Low Complexity Analog Components
Kaushik, Aryan; Arora, Aakash; Tsinos,Christos et al

Poster (2022, March)

In this paper, we aim to design an efficient and low hardware complexity based dual-function multiple-input multiple-output (MIMO) joint radar-communication (JRC) system. It is implemented via a low ... [more ▼]

In this paper, we aim to design an efficient and low hardware complexity based dual-function multiple-input multiple-output (MIMO) joint radar-communication (JRC) system. It is implemented via a low complexity analog architecture, constituted by a phase shifting network and variable gain amplifier. The proposed system exploits the multiple antenna transmitter for the simultaneous communication with multiple downlink users and radar target detection. The transmit waveform of the proposed JRC system is designed to minimize the downlink multi-user interference such that the desired radar beampattern is achieved and the architecture specific constraints are satisfied. The resulting optimization problem is non-convex and in general difficult to solve. We propose an efficient algorithmic solution based on the primal-dual framework. The numerical results show the effectiveness of the proposed approach. [less ▲]

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See detailExploring Mathematical concepts in an Ecosystem of STEAM Learning, consisting of Physical Objects, Digital Toolkits and Tutoring Systems, 3D Printing and Outdoor Mathematical Trails
Haas, Ben; Kreis, Yves UL; Lavicza, Zsolt et al

Poster (2022, February 04)

We performed several research studies on various technologies such as automated tutoring and GPS-assisted systems as well as Computer Assisted Design, Augmented Reality, and 3D Printing solutions; with ... [more ▼]

We performed several research studies on various technologies such as automated tutoring and GPS-assisted systems as well as Computer Assisted Design, Augmented Reality, and 3D Printing solutions; with various groups of teacher educators, teachers, students and parents. The selected technologies offered different opportunities and developed varied skills for each stakeholder group. This poster outlines our technology ecosystems with different target groups and core findings of our studies. [less ▲]

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See detailThe influence of tens and units inversion in a two-digit number matching task in German and French monolinguals and bilinguals
Lachelin, Remy UL; Poncin, Alexandre; Van Rinsveld, Amandine et al

Poster (2022)

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See detailProfiles of cannabis consumption among school-aged children in Luxembourg
Lopes Ferreira, Joana UL; Catunda, Carolina UL

Poster (2022)

Background: Cannabis is the most widely used illegal drug globally, with almost 200 million users in 2019. This use is associated with many negative health consequences and social problems, such as low ... [more ▼]

Background: Cannabis is the most widely used illegal drug globally, with almost 200 million users in 2019. This use is associated with many negative health consequences and social problems, such as low school performance and other drug use. Cannabis use can be articularly harmful if it starts early, if it’s excessive or if it occurs associated with other forms of problematic behaviours. A lot of health behaviours, good or bad, emerge during adolescence and remain through the life course. Changing unhealthy behaviours in adolescence would significantly impact society, such as reducing the load of disease, injuries, and economic costs. The objective of this study is to explore cannabis consumption profiles and the factors related to it during adolescence. Methods: This study is based on the 2017/2018 Health Behaviour in School-aged Children Luxembourg survey. Participated 6 880 adolescents, aged 12 to 18-year-old, that attended schools in Luxembourg that teach according to the national. Adolescents answered if they used cannabis during their lifetime and during the past month. Following, they were categorized into 4 groups: 1. never consumed cannabis in a lifetime; 2. consumed in a lifetime but not in the past month; 3. non-daily use during the past month and; 4. daily use (or almost) during the past month. To compare and characterize the groups, descriptive and bivariate analyzes were undertaken, as well as their significance level. Results: Results show that most of the adolescents (81.8%) never consumed cannabis in their lifetime; 9.4% declared a consumption during their lifetime but not the past month; 6.6% used during the past month, non-daily; and 2.2% used (almost) daily during the past month. Different profiles emerge between the groups, particularly with regard to socio-demographic characteristics and risky behaviours. In the case of social relationships and indicators of health and well-being, differences exist but are not as pronounced. Boys, older students and those who do not live with both parents are more likely to be part of groups that have used cannabis. In addition, most risk behaviours show a dose-response relationship with cannabis use. The increase in risky behaviours translates into not only a greater likelihood of using cannabis but also a greater frequency of use. Conclusion: The four different profiles evolve gradually with the frequency of cannabis consumption. This dose-effect relationship has been highlighted between cannabis consumption and the other variables present but is especially true for risk behaviours. Prevention strategies should distinguish adolescents from each of these groups, starting in early adolescence and focus on risk behaviours as a whole. [less ▲]

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See detailHow to catch a space debris
Yalcin, Baris Can UL; Martinez Luna, Carol UL; Hubert Delisle, Maxime UL et al

Poster (2021, November 18)

The partnership between SpaceR and Spacety Luxembourg aims to develop cutting edge active space debris removal solutions that can be implemented into small cube sats The solution will take the advantage ... [more ▼]

The partnership between SpaceR and Spacety Luxembourg aims to develop cutting edge active space debris removal solutions that can be implemented into small cube sats The solution will take the advantage of latest advancements in many tech domains, such as gecko like sticky adhesives and energy efficient shape memory alloy materials. [less ▲]

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See detailPoster: A Methodology for Semi-Automated CAN Bus Reverse Engineering
Buscemi, Alessio UL; Turcanu, Ion; German, Castignani et al

Poster (2021, November)

Semi-automated Controller Area Network (CAN) reverse engineering has been shown to provide decoding accuracy comparable to the manual approach, while reducing the time required to decode signals. However ... [more ▼]

Semi-automated Controller Area Network (CAN) reverse engineering has been shown to provide decoding accuracy comparable to the manual approach, while reducing the time required to decode signals. However, current approaches are invasive, as they make use of diagnostic messages injected through the On-Board Diagnostics (OBD-II) port and often require a high amount of non-CAN external data. In this work, we present a non-invasive universal methodology for semi-automated CAN bus reverse engineering, which is based on the taxonomy of CAN signals. The data collection is simplified and its time reduced from the current standard of up to an hour to few minutes. A mean recall of around 80 % is obtained. [less ▲]

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See detailPost-Urban Mining Automation and Digitalisation for a Closed- Loop Circular Construction
Akbarieh, Arghavan UL; Schäfer, Markus UL; Waldmann, Daniele UL et al

Poster (2021, October 13)

The large volume of in- and out-flow of raw materials to construction projects has a huge potential to be optimised for resource efficiency and waste reduction. With the recent awareness of the importance ... [more ▼]

The large volume of in- and out-flow of raw materials to construction projects has a huge potential to be optimised for resource efficiency and waste reduction. With the recent awareness of the importance of the circular economy, construction actors are aligning their practices to be more circular and sustainable. The concept of material banks is born out of this awareness in order to document the lifecycle information of materials and facilitate re-using them. The introduction of new cycles before individual materials reach their final lifecycle stages results in reduced negative environmental impacts. This paper presents a workflow by positioning different digital technologies to automate the procedures for reuse assessment: from the deconstructed building to M/C bank to new construction projects. This automation supports a practical material and component reuse, while it provides the necessary infrastructure to digitise and digitalise the post-deconstruction materials to be visualised, selected and used by future designers in Building Information Modelling (BIM)-based design and management environments. To this aim, the coupling of BIM, reality capturing technologies, additive manufacturing techniques, IoT and RFID sensors is also anticipated. [less ▲]

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See detailThe retrograde procedural memory in people with Parkinson’s disease with or without freezing of gait – a cross-sectional study
Pauly, Laure UL; Rauschenberger, Armin UL; Pauly, Claire UL et al

Poster (2021, September 17)

Objective: To investigate the retrograde procedural memory in people with typical Parkinson’s disease (PwP) with or without freezing of gait (FOG). We hypothesized that the retrograde procedural memory is ... [more ▼]

Objective: To investigate the retrograde procedural memory in people with typical Parkinson’s disease (PwP) with or without freezing of gait (FOG). We hypothesized that the retrograde procedural memory is more strongly impaired in patients with FOG (FOG+) than in patients without FOG (FOG-). Background: Given that cognitive functions, like executive control and automaticity, are crucial for mobility, it is of great importance to get a deeper knowledge of the cognitive impairment that may interfere with walking and causing gait disturbances in PwP, i.e. FOG. The integrity of retrograde procedural memory, the ability to execute skills that have been learned in earlier life stages, is essential for a person’s ability to complete routine, procedural activities like walking. As FOG is characterized as a de-automatization disorder, we hypothesized an impairment of the retrograde procedural memory in patients with FOG. Methods: A total of 194 patients from the Luxembourg Parkinson’s study were included into the cross-sectional study. All patients were assigned to the FOG+ / FOG- groups based on a semi-structured interview conducted by a study physician. The extended evaluation system of the cube copying test was applied to evaluate both the cube-drawing procedure, representing the retrograde procedural memory, and the final result, representing the visuo-constructive abilities (Pauly et al., 2020, MDS abstract). We compared the cube copying performance of n=97 FOG+ with n=97 age-, gender- and education-matched FOG-. Results: FOG+ scored lower on the cube copying procedure compared to the FOG- (p=0.027), which is suggestive of an impaired retrograde procedural memory in FOG+. No significant differences in the visuo-constructional abilities were detected (p=0.945). Conclusion: In line with FOG being considered a de-automatization of walking, a skill acquired in earlier life stages, the present results suggest that PwP with FOG have an impaired retrograde procedural memory in comparison to PwP without FOG. The results lend support to the ability of the extended evaluation system of the cube copying test to assess impaired retrograde procedural memory and help improve our understanding of behavioral symptoms in PwP. [less ▲]

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See detailMassive MIMO Downlink Transmission for LEO Satellite Communications
Li, Ke-Xin; You, Li; Wang, Jiaheng et al

Poster (2021, September)

We investigate the downlink (DL) transmit strategy for massive multiple-input multiple-output (MIMO) low-earthorbit (LEO) satellite communication (SATCOM) systems, in which only the slow-varying ... [more ▼]

We investigate the downlink (DL) transmit strategy for massive multiple-input multiple-output (MIMO) low-earthorbit (LEO) satellite communication (SATCOM) systems, in which only the slow-varying statistical channel state information is known at the transmitter side. First, we establish the massive MIMO LEO satellite channel model, in which the uniform planar arrays are deployed at both the satellite and user terminals (UTs). Building on the rank-one property of satellite channel matrices, we show that transmitting a single data stream to each UT is optimal for the ergodic sum rate maximization. This result is of great importance for massive MIMO LEO SATCOM systems, since the sophisticated design of transmit covariance matrices is turned into that of precoding vectors, with no loss of optimality at all. Furthermore, we conceive an algorithm to compute the precoding vectors. Simulation results show the significant performance gains of the proposed approaches over the previous schemes. [less ▲]

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See detailINVESTIGATING THE INFLUENCE OF PERSONALIZED MUSCULOSKELETAL MODELS ON THE CALCULATED STRESSES IN THE PELVIC RING
Soliman, Ahmed Abdelsalam Mohamed UL; Kedziora, Slawomir UL; Kelm, Jens et al

Poster (2021, September)

This study investigates the influence of personalizing musculoskeletal models (MS) on muscles, contact joints forces and on stresses in the pelvic ring bones during normal gait loading cycle. All ... [more ▼]

This study investigates the influence of personalizing musculoskeletal models (MS) on muscles, contact joints forces and on stresses in the pelvic ring bones during normal gait loading cycle. All calculated forces are utilized to predict stress states in pelvis bones using Finite Element (FE) software. Customized MS models provides more precise muscle and contact forces. Additionally, it enables more automatic coupling between MS and FE environments by data transfer. [less ▲]

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See detailFrom language policy to educational practices: early multilingual education in Luxembourg
Seele, Claudia; Kirsch, Claudine UL

Poster (2021, August 17)

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See detailModel bias and its impact on computer-aided diagnosis: A data-centric approach
Garcia Santa Cruz, Beatriz UL; Bossa, Matias Nicolas UL; Sölter, Jan UL et al

Poster (2021, August)

Machine learning and data-driven solutions open exciting opportunities in many disciplines including healthcare. The recent transition to this technology into real clinical settings brings new challenges ... [more ▼]

Machine learning and data-driven solutions open exciting opportunities in many disciplines including healthcare. The recent transition to this technology into real clinical settings brings new challenges. Such problems derive from several factors, including their dataset origin, composition and description, hampering their fairness and secure application. Considering the potential impact of incorrect predictions in applied-ML healthcare research is urgent. Undetected bias induced by inappropriate use of datasets and improper consideration of confounders prevents the translation of prediction models into clinical practice. Therefore, in this work, the use of available systematic tools to assess the risk of bias in models is employed as the first step to explore robust solutions for better dataset choice, dataset merge and design of the training and validation step during the ML development pipeline. [less ▲]

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See detailRelationship between Critical Consciousness and Multiculturalism? A comparison across four countries
Eickmann, Wibke; Murdock, Elke UL

Poster (2021, July 29)

Multiculturalism Ideology (MCI) describes the “appreciation of the value of cultural diversity for a society, and a need for mutual acceptance and accommodation that promotes equitable participation” ... [more ▼]

Multiculturalism Ideology (MCI) describes the “appreciation of the value of cultural diversity for a society, and a need for mutual acceptance and accommodation that promotes equitable participation” (Berry, 2016, p. 416f). The aim of the present study was to explore if and how diversity-related attitudes and the perception of less privileged members of society are linked and thus contribute to the growing body of research on social inequity awareness. Whilst some studies have focused on MCI and minority rights, awareness of structural discrimination and lowering prejudice, few have focused specifically on Critical Consciousness (CC), the reflection about inequalities in society and action taken to address them. Components of CC include Critical Reflection (Perceived Inequality and Egalitarianism), Political Efficacy (Internal and External), and Critical Action (Sociopolitical Participation). The present study draws on a quantitative design. An online questionnaire was launched in four countries, France, Luxembourg, Hong Kong, and Malaysia, which differ in their approaches in dealing with diversity. Measures included the Critical Consciousness Scale, the Political Efficacy Short Scale with the subscales regarding internal and external political efficacy and the Multicultural Ideology Scale (MCI). The questionnaire was made available in English, French and German. The total sample comprised 120 participants (68.2% female, Mage = 26.40, SDage = 9.71). Results indicate that MCI was highly positively correlated with Perceived Inequality and Egalitarianism and negatively with External Political Efficacy. Mean scores for CC components and MCI did not statistically differ across the four countries, while the correlation patterns between CC components and MCI were different. This finding suggests that CC may develop quite independently of cultural influences, as perception of unequal treatment and status differences between groups is an issue prevalent in all societies. More detailed results and implications as well as limitations of the present study will be discussed. [less ▲]

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See detailA Cubesat-ready Phase Synchronization Digital Payload for Coherent Distributed Remote Sensing Missions
Querol, Jorge UL; Merlano Duncan, Juan Carlos UL; Martinez Marrero, Liz UL et al

Poster (2021, July 15)

Distributed antenna arrays, fractionated payloads and cooperative platforms can provide unprecedented performance in the next generation of spaceborne communications and remote sensing systems. Remote ... [more ▼]

Distributed antenna arrays, fractionated payloads and cooperative platforms can provide unprecedented performance in the next generation of spaceborne communications and remote sensing systems. Remote phase synchronization of physically separated oscillators is the first step towards a coherent operation of distributed systems. This work shows the preliminary results of a TDD remote phase synchronization algorithm with a master-follower architecture. Herein, we describe the implementation and validation of the proposed algorithm. The implementation has been conducted in a Cubesat-ready software defined radio and validated at the end-to-end satellite communications testbed available at the University of Luxembourg. [less ▲]

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See detailInvestigating the influence of personalized musculoskeletal models on the calculated muscles and joints forces
Soliman, Ahmed Abdelsalam Mohamed UL; Kedziora, Slawomir UL; Kelm, Jens et al

Poster (2021, July)

It was the objective to analyze the influence of personalization of musculoskeletal models (MS) on muscle and contact joint forces for frequent daily movements. For normal gait cycle, we detect ... [more ▼]

It was the objective to analyze the influence of personalization of musculoskeletal models (MS) on muscle and contact joint forces for frequent daily movements. For normal gait cycle, we detect approximately 20% for some muscles attached to the pelvis, as well as for maximum hip-joint contact force. [less ▲]

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See detail𝑘-Pareto Optimality for Many-Objective Genetic Optimization
Ruppert, Jean; Aleksandrova, Marharyta UL; Engel, Thomas UL

Poster (2021, July)

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See detailInvestigating the associations of trajectories of depressive symptoms and self-perceived health and incident dementia : an unsupervised machine learning approach.
Klee, Matthias UL; Leist, Anja UL

Poster (2021, July)

Background: Risk factors for dementia show inter-individually varying trajectories over the lifespan. However, risk factors have been mainly investigated with one time-point assessments. New research ... [more ▼]

Background: Risk factors for dementia show inter-individually varying trajectories over the lifespan. However, risk factors have been mainly investigated with one time-point assessments. New research suggests that certain risk factor trajectories are associated with increased risk of adverse cognitive outcomes (Demnitz et al., 2020 [https://doi.org/10.1101/2020.05.20.20106963]; Singh-Manoux et al., 2018 [https://doi.org/10.1016/j.jalz.2017.06.2637]). However, it remains unclear how sequential and simultaneous changes of risk factors alter the individual risk for developing dementia. Testing the joint contribution of trajectories of depressive symptoms and self-perceived health on incidence of dementia, we hypothesized that consistently poor as well as deteriorating trajectories increase the risk for incident dementia, and explored possible interactions of the trajectories. Method: A total of 5,326 respondents to the SHARE survey, mean age 73.9 years, and 6 complete follow-ups spanning ~13 years, answered the EURO-D depression scale, self-perceived health (SPH) (t1-t5), and self-reported dementia diagnosis at last follow-up (t6). To investigate the predictive ability of distinct longitudinal trajectories, we applied unsupervised statistical learning methods (K-means cluster modelling). Clusters indicated distinct risk factor trajectories, which were used as exposures in stepwise logistic regressions to predict incident dementia, controlling for age, gender, education, and country. Result: Cluster analysis revealed five distinct trajectories each for SPH and EURO-D, with varying dementia incidence. In stepwise logistic regressions, respondents with trajectories “consistently poor health” and “consistently high depression” showed elevated risk of dementia (OR = 4.02 [1.39, 14.75] and OR = 2.26 [1.03, 4.95], respectively) compared to the combined baseline risk for “consistently low depression” and “consistently good health”. Interactions were not significant. However, respondents with the combination of “consistently high depression” and “consistently poor health” showed increased risk (N = 246; 6.1% dementia). Conclusion: Applying unsupervised machine learning is helpful to incorporate longitudinal information on depressive symptoms and self-perceived health and model these risk factors longitudinally to test their contribution to explain incidence of dementia. The predictive ability of the trajectories of depressive symptoms and self-perceived health for dementia indicates the potential for improving the identification of people at risk for developing dementia in late life by exploiting trajectory information readily accessible through regular medical check-ups in old age. [less ▲]

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See detailMulti-Antenna Data-Driven Eavesdropping Attacks and Symbol-Level Precoding Countermeasures
Mayouche, Abderrahmane UL; Alves Martins, Wallace UL; Tsinos, Christos UL et al

Poster (2021, June 21)

In this work, we consider secure communications in wireless multi-user (MU) multiple-input single-output (MISO) systems with channel coding in the presence of a multi-antenna eavesdropper (Eve), who is a ... [more ▼]

In this work, we consider secure communications in wireless multi-user (MU) multiple-input single-output (MISO) systems with channel coding in the presence of a multi-antenna eavesdropper (Eve), who is a legit user trying to eavesdrop other users. In this setting, we exploit machine learning (ML) tools to design soft and hard decoding schemes by using precoded pilot symbols as training data. The proposed ML frameworks allow an Eve to determine the transmitted message with high accuracy. We thereby show that MU-MISO systems are vulnerable to such eavesdropping attacks even when relatively secure transmission techniques are employed, such as symbol-level precoding (SLP). To counteract this attack, we propose two novel SLP-based schemes that increase the bit-error rate at Eve by impeding the learning process. We design these two security-enhanced schemes to meet different requirements regarding runtime, security, and power consumption. Simulation results validate both the ML-based eavesdropping attacks as well as the countermeasures, and show that the gain in security is achieved without affecting the decoding performance at the intended users. [less ▲]

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See detailVerbessern Entspannungsverfahren die Interozeptionsfähigkeit? – Eine 1-wöchige Intervention
Dierolf, Angelika UL; Gräfin von Königsmark, Benita; Gorji, Lilia et al

Poster (2021, June)

Verbessern Entspannungsverfahren die Interozeptionsfähigkeit? – Eine 1-wöchige Intervention Interozeption, die Wahrnehmung und Verarbeitung körpereigener Signale, ist ein zentraler Aspekt von Gesundheit ... [more ▼]

Verbessern Entspannungsverfahren die Interozeptionsfähigkeit? – Eine 1-wöchige Intervention Interozeption, die Wahrnehmung und Verarbeitung körpereigener Signale, ist ein zentraler Aspekt von Gesundheit und Krankheit. Eine gestörte Interozeptionsfähigkeit zeigt sich bei verschieden psychischen Erkrankungen, wie Depression oder auch Essstörungen. In der vorliegenden Studie wurde an 76 gesunden Studenten untersucht, ob sich die interozeptive Genauigkeit und das interozeptive Bewusstsein durch eine 5-tägige körperbezogene Imaginationsübung per Audiodatei verbessern lassen. Als Kontrollbedingung diente eine nicht-körperbezogene Traumreise und nicht-entspannungsbezogene Podcasts der Serie ZeitWissen. Die Erhebung erfolgte online. Vor und nach der 5-tägigen Intervention wurden interozeptive Genauigkeit (Interoceptive Accuracy Scale (IAs)) und interozeptives Bewusstsein (Multidimensional Assessment of Interoceptive Awareness (MAIA)) erfasst. Erste Ergebnisse zeigen eine interventionsunabhängige Zunahme der interozeptiven Genauigkeit und des interozeptiven Bewusstsein nach allen Interventionen. Unabhängig von Intervention und Messzeitpunkt scheinen allerdings depressive, Angst- und Stresssymptome, gemessen mit Depressions-Angst-Stress-Skalen (DASS), sowie psychische Belastungen durch die aktuelle Covid-19 Pandemie insbesondere interozeptives Bewusstsein und in geringerem Ausmaß interozeptive Genauigkeit negativ zu beeinflussen. Die wöchentliche Häufigkeit, mit der generell eigene Achtsamkeits- oder Entspannungsübungen durchgeführt werden, wirkt sich positiv auf das interozeptive Bewusstsein aus. Insgesamt scheint Interozeptionsfähigkeit auch durch eine körperbezogene kurze, intensive imaginative Entspannungsübung in gesunden jungen Erwachsenen nicht verbessert zu werden, im Gegensatz zu regelmäßigem Yoga-, Mediations- oder Achtsamkeitstraining, welches interozeptives Bewusstsein positiv beeinflusst. [less ▲]

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See detailEnergy Efficiency Optimization Technique for SWIPT-enabled Multi-Group Multicasting Systems with Heterogeneous Users
Gautam, Sumit UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

Poster (2021, June)

We consider a multi-group (MG) multicasting (MC) system wherein a multi-antenna transmitter serves heterogeneous users capable of either information decoding (ID) or energy harvesting (EH), or both. In ... [more ▼]

We consider a multi-group (MG) multicasting (MC) system wherein a multi-antenna transmitter serves heterogeneous users capable of either information decoding (ID) or energy harvesting (EH), or both. In this context, we investigate a precoder design framework to explicitly serve the ID and EH users categorized within certain MC and EH groups. Specifically, the ID users are categorized within multiple MC groups while the EH users are a part of single (last) group. We formulate a problem to optimize the energy efficiency in the considered scenario under a quality-of-service (QoS) constraint. An algorithm based on Dinkelback method, slack-variable replacement, and second-order conic programming (SOCP)/semi-definite relaxation (SDR) is proposed to obtain a suitable solution for the above-mentioned fractional-objective dependent non-convex problem. Simulation results illustrate the benefits of proposed algorithm under several operating conditions and parameter values, while drawing a comparison between the two proposed methods. [less ▲]

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See detailA data-driven computational framework to provide deformable solids with the sense of touch
Hurtado Cathalifaud, Diego Rene UL

Poster (2021, May 21)

A data-driven, probabilistic, computational framework will be developed that provides a deformable solid with the sense of 'touch', so that it can detect the shape and mechanical behaviour of its ... [more ▼]

A data-driven, probabilistic, computational framework will be developed that provides a deformable solid with the sense of 'touch', so that it can detect the shape and mechanical behaviour of its environment. The framework will rely on three modules: a mechanical model to simulate the contact between the deformable solid and its environment, a machine learning module to rapidly emulate the mechanical simulations, and a probabilistic framework to identify the shape and mechanical behaviour of the solid’s environment. [less ▲]

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See detailScience Inequalities
Kozlowski, Diego UL

Poster (2021, May 21)

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See detailIndividually Tailored Neurofeedback
Uslu, Sinan UL

Poster (2021, May 21)

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See detailGNSS-R GRAZING ANGLE FOR SEA ICE ALTIMETRY
Navarro Buendìa, Raquel UL

Poster (2021, May 21)

The grazing angle signals of opportunities from Global Navigation Satellite System (GNSS) are used to perform precise sea-ice altimetry. The novel GNSS-Reflectometry (GNSS-R) would help to better ... [more ▼]

The grazing angle signals of opportunities from Global Navigation Satellite System (GNSS) are used to perform precise sea-ice altimetry. The novel GNSS-Reflectometry (GNSS-R) would help to better understand the sea-ice distribution and classification in the polar regions. [less ▲]

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See detailPredicting Vulnerability to Poverty with Machine Learning
Taye, Alemayehu UL; d'Ambrosio, Conchita UL

Poster (2021, May 21)

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See detailFinancial Difficulties and Gender as Moderators of How Workforce Involvement and Transitions Affect the Health of Older Europeans
Settels, Jason UL

Poster (2021, May 05)

A prominent demographic trend throughout the industrialized world is population aging. In response to concerns about labor force shortages, many European nations have enacted policies aimed at keeping ... [more ▼]

A prominent demographic trend throughout the industrialized world is population aging. In response to concerns about labor force shortages, many European nations have enacted policies aimed at keeping older persons employed. Understanding how later life paid work is associated with health is thus important. Using an older sample from waves six and seven of the Survey of Health, Ageing and Retirement in Europe (N = 38,884), this study shows how a set of six workforce involvement/transitions patterns are associated with health. Also studied are whether these effects are moderated by financial difficulties. Later life paid work is found to be beneficial for health, and this benefit is accentuated by financial difficulties. The findings also reveal moderation by gender. Older women’s more fragmented employment histories cause stable paid work to be of less benefit for addressing their financial difficulties. Furthermore, older women are especially vulnerable to unemployment while undergoing financial troubles. [less ▲]

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See detailPrivacy-Preserving PayString Service
Scheidt de Cristo, Flaviene UL; Shbair, Wazen UL; Trestioreanu, Lucian Andrei UL et al

Poster (2021, May)

PayString is an initiative to make payment identifiers global and human-readable, facilitating the exchange of payment information. However, the reference implementation lacks privacy and security ... [more ▼]

PayString is an initiative to make payment identifiers global and human-readable, facilitating the exchange of payment information. However, the reference implementation lacks privacy and security features, making it possible for anyone to access the payment information as long as the PayString identifier is known. Also, this paper presents the first performance evaluation of PayString. Via a large-scale testbed, our experimental results show an overhead which, given the privacy and security advantages offered, is acceptable in practice, thus making the proposed solution feasible. [less ▲]

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See detail5G-SpaceLab
Querol, Jorge UL; Abdalla, Abdelrahman UL; Bokal, Zhanna UL et al

Poster (2021, April 19)

The new phase of space exploration involves a growing number of human and robotic missions with varying communication and service requirements. Continuous, maximum coverage of areas where activities are ... [more ▼]

The new phase of space exploration involves a growing number of human and robotic missions with varying communication and service requirements. Continuous, maximum coverage of areas where activities are concentrated and orbiting missions (single spacecraft or constellations) around the Earth, Moon or Mars will be particularly challenging. The standardization of the 5G Non-Terrestrial Networks (NTN) has already begun [1], and nothing prevents 5G from becoming a common communications standard supporting space resource missions [2]. The 5G Space Communications Lab (5G-SpaceLab) is an interdisciplinary experimental platform, funded by the Luxembourg Space Agency and is part of the Space Research Program of SnT. The lab allows users to design and emulate realistic space communications and control scenarios for the next-generation of space applications. The capabilities of the 5G-SpaceLab testbed combine the experience of different disciplines including space communications, space and satellite mission design, and space robotics. The most relevant include the demonstration of SDR 5G NTN terminals including NB-IoT, emulation of space communications channel scenarios (e.g. link budget, delay, Doppler…), small satellite platform and payload design and testing, satellite swarm flight formation, lunar rover and robotic arm control and AI-powered telerobotics. Earth-Moon communications is one of the scenarios demonstrated in the 5G-SpaceLab. Bidirectional communication for the teleoperation of lunar rovers for near real-time operations including data collection and sensors feedback will be tested. AI-based approaches for perception and control will be developed to overcome communication delays and to provide safer, trustworthy, and efficient remote control of the rovers. [1] 3GPP Release 17 Timeline. [Online]. Available: https://www.3gpp.org/release-17 [2] Nokia, Nokia selected by NASA to build first ever cellular network on the Moon. [Online]. Available: https://www.nokia.com/about-us/news/releases/2020/10/19/nokia-selected-by-nasa-to-build-first-ever-cellular-network-on-the-moon/ [less ▲]

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See detailBridging the space systems performance-reliability gap for future deep space resources exploration and exploitation.
Pinto Gouveia, Ines UL; Graczyk, Rafal UL; Volp, Marcus UL

Poster (2021, April)

In building equipment for space exploitation, one has to trade system robustness for the high processing capabilities and low energy consumption. The high performance, low robustness approach, is ... [more ▼]

In building equipment for space exploitation, one has to trade system robustness for the high processing capabilities and low energy consumption. The high performance, low robustness approach, is acceptable, especially in Earths’ vicinity. However, in more demanding (especially high-radiation) environments, attempts had disappointing outcomes. The processing-reliability gap, between highly reliable and highly performant systems, spans 2-3 orders of magnitude. This gap brings hope, that some of this excess processing power can be utilized, in building a combination of hardware and software mechanisms that is capable of increasing robustness and resilience of otherwise susceptible semiconductor devices, while allowing to harness the remaining processing power to build affordable space systems with large degrees of autonomy, rich functionality and high bandwidth. At the CritiX research group, we aim to bridge this performance-reliability gap, by researching the enabling building blocks for constructing more reliable and more secure System-on-Chips. [less ▲]

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See detailModeling and Optimization of RF-Energy Harvesting-assisted Quantum Battery System
Gautam, Sumit UL; Sharma, Shree Krishna UL; Chatzinotas, Symeon UL et al

Poster (2021, April)

The quest for finding a small-sized energy supply to run the small-scale wireless gadgets, with almost an infinite lifetime, has intrigued humankind since past several decades. In this context, the ... [more ▼]

The quest for finding a small-sized energy supply to run the small-scale wireless gadgets, with almost an infinite lifetime, has intrigued humankind since past several decades. In this context, the concept of Quantum batteries has come into limelight more recently to serve the purpose. However, the main issue revolving around the closed-system design of Quantum batteries is to ensure a loss-less environment, which is extremely difficult to realize in practice. In this paper, we present the modeling and optimization aspects of a Radio-Frequency (RF) Energy Harvesting (EH) assisted Quantum battery, wherein several EH modules (in the form of micro- or nano- sized integrated circuits (ICs)) help each of the involved Quantum sources achieve the so-called quasi-stable state. Specifically, a micro-controller manages the overall harvested energy from the RF-EH ICs and a photon emitting device, such that the emitted photons are absorbed by the electrons in the Quantum sources. In order to precisely model and optimize the considered framework, we formulate a transmit power minimization problem for an RF-based wireless system to optimize the number of RF-EH ICs under the given EH constraints at the Quantum battery-enabled wireless device. We obtain an analytical solution to the above-mentioned problem using a rational approach, while additionally seeking another solution obtained via a non-linear program solver. The effectiveness of the proposed technique is reported in the form of numerical results by taking a range of system parameters into account. [less ▲]

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See detailWhat Are Scientific Models? Problems with the Fiction View
Durlacher, Thomas UL

Poster (2021, February 05)

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See detailPrinciples for setting single or multiline control based on network characteristics
Laskaris, Georgios; Cats, Oded; Jenelius, Erik et al

Poster (2021, January)

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See detailSystematic Analysis and Modelling of Profit Maximization on Carsharing
Giorgione, Giulio UL; Kliazovich, Dzmitry; Bolzani, Luca UL et al

Poster (2021, January)

The success of carsharing as a new and more sustainable way of travel is moving private car ownership towards a service use model. Competitivity is an essential aspect of this service and ways to increase ... [more ▼]

The success of carsharing as a new and more sustainable way of travel is moving private car ownership towards a service use model. Competitivity is an essential aspect of this service and ways to increase profit while offering the most appealing service are still getting explored. Among others, dynamic pricing strategies can be designed to increase profit by attracting more users, selling more rental hours or maximizing fleet utilization. In this paper, we propose an experimental method aimed at developing a model for maximizing service profit. Using agent-based modeling to generate realistic scenarios, we analyze pricing as a function of the potential demand (i.e. number of members) and supply (hours of booking supplied). The process of reaching the maximum profit consists of testing various combinations of pricing - demand and pricing – supply ranges in order to find the price that maximize the profit for every demand and supply level. Once the optimal prices are known, a polynomial fitting and an optimization method are used to generate a function linking all the maximal profit obtaining the advised price to offer for any specific supply levels. Results show how the profit only slightly depends on the variability of the potential demand, while it strongly depends on the amount of supply. It is then shown how it is possible to obtain a linear relation that maximizes the profit in function of the price offered once the supply is known. [less ▲]

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See detailIntelligent Reflecting Surface-assisted MU-MISO Systems with Imperfect Hardware: Channel Estimation and Beamforming Design
Papazafeiropoulos, Anastasios; Pan, Cunhua; Kourtessis, Pandelis et al

Poster (2021)

Intelligent reflecting surface (IRS), consisting of lowcost passive elements, is a promising technology for improving the spectral and energy efficiency of the fifth-generation (5G) and beyond networks ... [more ▼]

Intelligent reflecting surface (IRS), consisting of lowcost passive elements, is a promising technology for improving the spectral and energy efficiency of the fifth-generation (5G) and beyond networks. It is also noteworthy that an IRS can shape the reflected signal propagation. Most works in IRSassisted systems have ignored the impact of the inevitable residual hardware impairments (HWIs) at both the transceiver hardware and the IRS while any relevant works have addressed only simple scenarios, e.g., with single-antenna network nodes and/or without taking the randomness of phase noise at the IRS into account. In this work, we aim at filling up this gap by considering a general IRS-assisted multi-user (MU) multiple-input single-output (MISO) system with imperfect channel state information (CSI) and correlated Rayleigh fading. In parallel, we present a general computationally efficient methodology for IRS reflect beamforming (RB) optimization. Specifically, we introduce an advantageous channel estimation (CE) method for such systems accounting for the HWIs. Moreover, we derive the uplink achievable spectral efficiency (SE) with maximal-ratio combining (MRC) receiver, displaying three significant advantages being: 1) its closed-form expression, 2) its dependence only on large-scale statistics, and 3) its low training overhead. Notably, by exploiting the first two benefits, we achieve to perform optimization with respect to the that can take place only at every several coherence intervals, and thus, reduces significantly the computational cost compared to other methods which require frequent phase optimization. Among the insightful observations, we highlight that uncorrelated Rayleigh fading does not allow optimization of the SE, which makes the application of an IRS ineffective. Also, in the case that the phase drifts, describing the distortion of the phases in the RBM, are uniformly distributed, the presence of an IRS provides no advantage. The analytical results outperform previous works and are verified by Monte-Carlo (MC) simulations. [less ▲]

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See detailDefining the Pre-Examination Experience of MRI patients through Affective Interaction.
van Weert, Katja; Chen, Tianyi; Verburg, Pepijn et al

Poster (2021)

For many patients, Magnetic Resonance Imaging (MRI) experiences are uncomfortable and associated with high levels of anxiety and stress. Such negative experiences may interfere with image quality and ... [more ▼]

For many patients, Magnetic Resonance Imaging (MRI) experiences are uncomfortable and associated with high levels of anxiety and stress. Such negative experiences may interfere with image quality and increase examination time. It is therefore necessary to understand the mental states of the patients prior to the examination in order to provide stress-relieving measures. Studies exploring MRI-related anxiety and interventions to alleviate it have typically relied on self-reported data (e.g. STAI-6 questionnaire) or psychophysiological measures [1], usually in the waiting room. One could however benefit from an alternative measurement approach to overcome the limitations of current methods. The purpose of our study is to develop a tool for measuring mental states in the context of MRI experiences and explore the suitability of various sensors to detect anxiety. [less ▲]

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See detailOngoing sound changes in the Luxembourgish vowel system
Gilles, Peter UL

Poster (2021)

Detailed reference viewed: 47 (2 UL)