Recursive UE Localization for a Multi-RIS-Assisted Wireless System in an Obstacle-Dense Environment

Scientific Conference (in press)

Accurate user equipment (UE) localization in an obstacle-dense environment is quite challenging due to the insufficiency of line-of-sight (LoS) links. However, the reconfigurable intelligent surface (RIS ... [more ▼]

Accurate user equipment (UE) localization in an obstacle-dense environment is quite challenging due to the insufficiency of line-of-sight (LoS) links. However, the reconfigurable intelligent surface (RIS) has the potential for offering alternative RIS-assisted LoS links to refine the localization results. In this paper, a recursive localization scheme is proposed based on an iterative RIS selection strategy, with the help of prior knowledge of the propagation environment. And numerical results based on a geometry-based channel simulator in a typical composite urban environment exhibit the improvement of localization accuracy. [less ▲]

Maschinelles Lernen in der automatischen Auswertung von Punktwolken: Beispiele der Erfahrungen an der Universität Luxemburg

Scientific Conference (2023, October 07)

Intérêt de la participation des parents dans un modèle de Réponse à l’Intervention (RàI) ou dans un Système de Soutien à Paliers Multiples (SSPM) : une récension des écrits

Scientific Conference (2023, April 03)

Avec la démocratisation de l’enseignement et la multiplication des profils d’apprenants, l’institution scolaire a rapidement été confrontée à la nécessité d’étudier comment les besoins des élèves sont ... [more ▼]

Avec la démocratisation de l’enseignement et la multiplication des profils d’apprenants, l’institution scolaire a rapidement été confrontée à la nécessité d’étudier comment les besoins des élèves sont pris en compte par le système et comment les pratiques éducatives lui sont adaptées. C’est dans ce contexte qu’au début des années 2000, le modèle de réponse à l’intervention (RàI) a vu le jour. Il se définit comme une approche visant l’identification des élèves en difficulté et la mise en place d’une intervention ciblée sur les besoins de l’apprenant (Desrochers & Guay, 2020). Au fil des années, ce modèle RàI s’est intensifié et élargi à de nombreux domaines d’apprentissage mais aussi à la gestion du comportement des élèves. Cet élargissement du champ d’action initial a amené à renommer l’appellation de l’approche en Système de Soutien à Paliers Multiples (SSPM). Si la qualité de l’enseignement en classe et le soutien additionnel apporté aux élèves en difficulté semblent constituer le socle des interventions mobilisées dans le cadre du modèle RàI ou de l’approche en SSPM, il semble que l’engagement parental et la collaboration famille-école pourraient constituer un apport intéressant. En tant que premiers agents de socialisation de l’enfant et compte tenu de l’influence importante des familles sur la réussite développementale et éducative des enfants, la promotion de l’engagement parental et du partenariat famille-école présente un grand intérêt. Or, peu d’études ont, à ce jour, associé la facette famille à un modèle SSPM. Depuis plus de vingt années, l’engagement parental et le partenariat avec les parents constituent une thématique de recherche dont l’intérêt ne cesse de croître. Des synthèses récentes (par exemple, Axford et al., 2019 ; Englund et al., 2004 ; Kim et al., 2020, Roy & Giraldo-García, 2018 ; Huat See & Gorard, 2015), soulignent à quel point les relations école-famille ainsi que l’engagement parental peuvent avoir une influence significative et positive à la fois sur les performances scolaires mais aussi sur des variables conatives. Toutes ces études semblent converger vers le constat que la participation des parents a une influence positive sur la scolarité des élèves. Or, comme le rappellent Castro et al. (2015), ces études souffrent d’un manque d’homogénéisation des concepts à l’étude ; ce qui fait de la participation des parents un phénomène multiforme et multidimensionnel. En outre, il semble que peu d’études incluent un incitant à mettre en place une stratégie parentale particulière de soutien au cursus scolaire de l’enfant (Lawson, 2015). Cependant, il semble que l’école comme les familles se demandent quelles sont les façons les plus efficaces de collaborer pour optimiser les effets de l’engagement parental (Jeynes, 2012). Il apparait que le plus souvent les démarches et les actions sont davantage centrées sur l’école (Kanouté, 2006) qui tendent à placer les familles dans des rôles éducatifs mineurs (participation aux réunions de parents, par exemple). Toutefois, Garbacz et al. (2008) soutiennent qu’une approche d’implication parentale basée sur le partenariat favoriserait le renforcement des compétences des familles comme du personnel scolaire en identifiant et en soutenant les ressources des deux acteurs. Selon les auteurs, cette approche serait efficace car elle repose sur le principe d’une participation active des familles depuis l’identification des besoins, l’établissement de l’intervention et l’acquisition de nouvelles compétences plutôt que sur une réception passive d’une intervention externe faites par des professionnels. Ajoutons encore avec Larivée (2012) que pour renforcer l’efficacité des programmes d’implication parentale, il est important de concevoir les interventions en se référant aux données probantes de la recherche scientifique. Nous nous demandons si, par conséquent, le fait de renforcer la participation des parents dans la scolarité de leur enfant, au sein du modèle SSPM, dans le cadre d’un véritable partenariat école-famille autour d’une compétence d’apprentissage particulière, pourrait renforcer l’influence positive de ce soutien parental sur le développement scolaire de l’enfant tant au niveau des apprentissages scolaires (numératie et littératie) que de ses compétences socio-émotionnelles. C’est donc à travers une récension des écrits que nous cherchons à mettre en évidence l’intérêt de la participation des parents à un modèle de RàI ou une approche basée sur un SSPM. Pour réaliser cette synthèse, nous avons procédé de la façon suivante. Nous avons mené une recension de textes sur la participation des parents, le RàI ou le SSPM. Pour ce faire, nous avons eu recours à la base de données Education Research Complete. Nous avons utilisé les mots-clefs suivants : participation parentale, engagement parental ou investissement parental, Réponse à l’Intervention (RàI), Système de Soutien à Paliers Multiples (SSPM), numératie, littératie ou compétences socio-émotionnelles, ainsi que leur traduction en anglais : Response to intervention, Multi-tiered system of support, parental involvement ou parent engagement ou parent participation, numeracy, litteracy or Social-Emotional Learning (SEL). Les critères utilisés pour sélectionner les articles sont les suivants : 1) l’article est issu d’une revue à comité de lecture ; 2) l’article est disponible en langue française ou anglaise ; 3) l’article utilise une méthodologie qualitative et/ou quantitative étudiant l’intérêt d’une participation des parents dans un modèle RàI ou dans une approche en SSPM visant le développement de la numératie, de la littératie ou le développement socio-émotionnel chez des élèves du préscolaire et du primaire. Ce sont les résultats détaillés de cette récension d’écrits qui feront l’objet de la communication. Bibliographie Axford, N., Berry, V., Lloyd, J., Moore, D., Rogers, M., Hurst, A., Blockley, K., Durkin,H. and Minton, J. (2019) How Can Schools Support Parents’ Engagement in their Children’s Learning? Evidence from Research and Practice. London: Education Endowment Foundation. Report available from: https://educationendowmentfoundation.org.uk/evidence-summaries/evidence-reviews/parental-engagement/ (retrieved February 2022). Castro, M., Expósito-Casas, E., López-Martín, E., Lizasoain, L., Navarro-Asencio, E., & Gaviria, J. (2015). Parental involvement on student academic achievement: A meta-analysis. Educational Research Review, 14, 33-46. http://dx.doi.org/10.1016/j.edurev.2015.01.002 Englund, M. M., Luckner, A. E., Whaley, G. J. L., & Egeland, B. (2004). Children's Achievement in Early Elementary School: Longitudinal Effects of Parental Involvement, Expectations, and Quality of Assistance. Journal of Educational Psychology, 96(4), 723–730. https://doi.org/10.1037/0022-0663.96.4.723 Garbacz, S. & Woods, Kathryn & Swanger-Gagné, Michelle & Taylor, Ashley & Black, Kathryn & Sheridan, Susan. (2008). The Effectiveness of a Partnership-Centered Approach in Conjoint Behavioral Consultation. School Psychology Quarterly, 23(3), 313-326. 10.1037/1045-3830.23.3.313. Huat See, B., & Gorard, S. (2015). The role of parents in young people’s education—a critical review of the causal evidence. Oxford Review of Education, 41, 346-366. [less ▲]

Continuer à faire réseau : le regard d’une chercheuse sur le projet Respadon (conclusion de la journée).

Scientific Conference (2023, March 13)

L’équipe de ResPaDon organise une journée d’échange autour des résultats et des perspectives de ce projet débuté en mars 2021. Des conditions d’accès aux collectes collaboratives, des enjeux juridiques à ... [more ▼]

L’équipe de ResPaDon organise une journée d’échange autour des résultats et des perspectives de ce projet débuté en mars 2021. Des conditions d’accès aux collectes collaboratives, des enjeux juridiques à la coopération entre acteurs nationaux et établissements de proximité, le Réseau de Partenaires pour l’exploration et l’analyse de données numériques (ResPaDon) propose de partager les résultats de sa démarche pour développer les usages scientifiques de la collection des archives du dépôt légal du web. [less ▲]

Diversifikation im Klassenzimmer – ein Einwegspiegel?

Scientific Conference (2023, March 01)

Subjektives Wohlbefinden und akademische Leistung in der Grundschule: Längsschnittliche Befunde von der 3. bis zum 5. Klasse.

Scientific Conference (2023, February 28)

Investigation of OpenFOAM-XDEM momentum coupling results for AWJC Nozzle using preCICE

Scientific Conference (2023, February 14)

The high-speed water jet is the momentum source in an Abrasive Water Jet Cutting Nozzle. This momentum is transferred to the abrasive particles & the air within the nozzle. This leads to turbulent ... [more ▼]

The high-speed water jet is the momentum source in an Abrasive Water Jet Cutting Nozzle. This momentum is transferred to the abrasive particles & the air within the nozzle. This leads to turbulent & complex particle-laden flow in the nozzle. These flow conditions can influence particle impacts on the nozzle, thus influencing erosion. Hence it is imperative that this complex particle-laden flow is captured correctly. The momentum exchange can be directly from the water jet to the particles or indirectly through the airflow. In this work, we investigate these fluid-particle momentum exchanges. Our prototype uses preCICE for volumetric coupling of XDEM (for the particle motion), & OpenFOAM (for the fluid). XDEM uses fluid flow conditions to compute the forces acting on particles. XDEM computes the particle momentum source that is injected into the fluid solver. The results of the coupled simulation align with literature & can be extended to include the FEM component for erosion predictions. [less ▲]

Teachers´ stereotypical beliefs and expectations: A systematic review of studies focusing on intersectionality of students’ gender and ethnicity

Scientific Conference (2023, February 01)

EMN Inform "Transition of unaccompanied minors to adulthood"

Scientific Conference (2023, January 31)

This presentation shares the main results of the EMN Inform Transition of unaccompanied minors to adulthood" indicating what are the challenges that unaccompanied minors confront when they reach adulthood ... [more ▼]

This presentation shares the main results of the EMN Inform Transition of unaccompanied minors to adulthood" indicating what are the challenges that unaccompanied minors confront when they reach adulthood and how Member States respond to this situation. [less ▲]

New results in finite mixture modeling

Scientific Conference (2023, January 05)

XRP-NDN overlay: Improving the Communication Efficiency of Consensus-Validation based Blockchains with an NDN Overlay

Scientific Conference (2023)

With growing adoption of Distributed Ledger Technologies, their networks must scale while maintaining efficient communication for the underlying consensus and replication mechanisms. New content ... [more ▼]

With growing adoption of Distributed Ledger Technologies, their networks must scale while maintaining efficient communication for the underlying consensus and replication mechanisms. New content distribution concepts like Named Data Networking create opportunities to achieve this goal. We present and evaluate XRP-NDN overlay, a solution to increase communication efficiency for consensus-validation blockchains like XRP Ledger. We send consensus messages over different communication models and show that the chosen model lowers the number of messages at node level to minimum, while maintaining or improving performance by leveraging overlay advantages. [less ▲]

Deep Learning-Based Device-Free Localization in Wireless Sensor Networks

Scientific Conference (2023)

Location-based services are witnessing a rise in popularity owing to their key features of delivering personalized digital experience. The recent developments in wireless sensing techniques make the ... [more ▼]

Location-based services are witnessing a rise in popularity owing to their key features of delivering personalized digital experience. The recent developments in wireless sensing techniques make the realization of device-free localization (DFL) feasible within wireless sensor network (WSN) architectures. The DFL is an emerging technology that utilizes radio signal information for detecting and positioning a passive movable target without attached devices. However, determining the characteristics of the massive raw signals and extracting meaningful discriminative features relevant to the localization are highly intricate tasks due to the different patterns associated with different locations. To overcome these issues, deep learning (DL) techniques can be utilized here owing to their remarkable performance gains in similar practical problems. In this direction, we propose a DFL framework consists of multiple convolutional neural network (CNN) layers along with deep autoencoders based on the restricted Boltzmann machines (RBM) to construct a convolutional deep belief network (CDBN) for features recognition and extracting. Each CNN layer has stochastic pooling to sample down the feature map and reduced the dimensions of the required data without losing important information. This dimensionality reduction can alleviate the heavy computation while ensuring precise localization. The proposed framework is validated using real experimental dataset. The results show that the proposed model is able to achieve a high accuracy of 98% with reduced data dimensions and low signal-to-noise ratios (SNRs). [less ▲]

Schedulability Analysis of CAN and CAN FD Authentication

Scientific Conference (2023)

Ensuring the data integrity of messages transmitted over the Controller Area Network (CAN) bus and other vehicular networks is achieved through the implementation of cryptographic authentication protocols ... [more ▼]

Ensuring the data integrity of messages transmitted over the Controller Area Network (CAN) bus and other vehicular networks is achieved through the implementation of cryptographic authentication protocols. However, these protocols raise concerns about a significant increase in response time due to the restrictions on CAN frame size and bandwidth. This paper presents a comprehensive analysis of the impact on response time of CAN and CAN Flexible Data-rate (CAN FD) messages with the implementation of cryptographic message authentication codes (MACs) and the periodic transmission of these codes. Our evaluation is based on a randomized schedulability experiment to provide insights into the overhead incurred by adding authentication to the frame payloads. [less ▲]

Exploring the potential of Google Popular Times for transit demand estimation

Scientific Conference (2023)

Towards assimilating SAR data into an anisotropic model of an underground aquifer

Scientific Conference (2023)

In this study, we aim to shed light on the feasibility of assimilating synthetic aperture radar (SAR) data into a partial differential equation-based model of a poroelastic homogeneous aquifer with ... [more ▼]

In this study, we aim to shed light on the feasibility of assimilating synthetic aperture radar (SAR) data into a partial differential equation-based model of a poroelastic homogeneous aquifer with anisotropic hydraulic conductivity (AHC). Although other authors [1] have considered the problem of assimilating SAR data into a poroelastic model that uses an inhomogeneous isotropic random field model for hydraulic conductivity, to the best of our knowledge, our study is the first to consider assimilating SAR data into a poroelastic model with AHC. Our study is inspired by the work of [2] where an aquifer test is performed on the Anderson Junction aquifer in southwestern Utah. Due to the inherent preferential direction of the fractured sandstone at the Anderson Junction site, the ratio of hydraulic conductivity along the principal axes can be on the order of 24 to 1. We build an anisotropically conductive poroelastic finite element model of the Anderson Junction site that can predict the coupled fluid flow and mechanical displacements. Our results show that the effective elastic response of the aquifer on the Earth’s surface has an anisotropic nature driven by the underlying anisotropy in the fluid problem, even when the elasticity problem is assumed to be isotropic. We interpret these results in the context of using SAR data to improve the characterization of aquifer systems, like the Anderson Junction site, with strongly anisotropic behavior. The Doctoral Training Unit Data-driven computational modelling and applications (DRIVEN) is funded by the Luxembourg National Research Fund under the PRIDE programme (PRIDE17/12252781). [1] Amal Alghamdi. Bayesian inverse problems for quasi-static poroelasticity with application to ground water aquifer characterization from geodetic data. PhD thesis, 2020. https://repositories.lib.utexas.edu/handle/2152/86231. [2] Victor M. Heilweil and Paul A. Hsieh. Determining Anisotropic Transmissivity Using a Simplified Papadopulos Method. Groundwater, 44(5):749–753, 2006. 10.1111/j.1745-6584.2006.00210.x [less ▲]

On Improving Slant Wet delays for Tracking Severe Weather Events: An evaluation During Two Storms in Europe

Scientific Conference (2022, December 14)

Climate change has led to an increase in the frequency and severity of weather events with intense precipitation and, subsequently, a greater susceptibility of communities around the world to flash ... [more ▼]

Climate change has led to an increase in the frequency and severity of weather events with intense precipitation and, subsequently, a greater susceptibility of communities around the world to flash flooding. Networks of ground-based Global Navigation Satellite System (GNSS) stations enable the measurement of integrated water vapor along slant pathways, providing three-dimensional (3D) water vapor distributions at low-cost and in real-time. This makes these data a valuable complementary source of information for tracking storm events and predicting their paths. However, it is well established that residual modelling errors and multipath (MP) effects at GNSS stations do impact incoming signals, especially at low elevations and during storms when the atmospheric conditions change rapidly. Until now, the bulk of GNSS products for meteorology are estimates of the more conventional zenith total delays and horizontal gradients, but these products may not be most appropriate for determining 3D distributions of water vapor during convective storm events. In this study we investigate the impact of residual-phase-corrected and multipath-corrected slant wet delay (SWD) estimates on tracking extreme weather events using two events in Europe that led to flooding, damage to property and loss of life. We employed Precise Point Positioning (PPP) with integer ambiguity resolution to generate station-specific MP correction maps. The spatial stacking was carried out in congruent cells with an optimal resolution in elevation and azimuth at the local horizon but with decreasing azimuth resolution as the elevation angle increases. This permits an approximately equal number of observations allocated to each cell. In our analysis we recovered the one-way SWD by adding GNSS post-fit phase residuals, representing the non-isotropic component of the SWD, i.e., the higher-order inhomogeneity. Using the derived MP maps in a final step, the one-way SWD were improved to employ them for the analysis of the weather event. Moreover, we validated the SWD between ground-based water-vapor radiometry and GNSS-derived SWD for different elevation angles. Furthermore, the spatio-temporal fluctuations in the SWD as measured by GNSS closely mirrored the moisture field from the ERA5 re-analysis associated with this severe weather event [less ▲]

High-Performance Computing for the simulation of particles with the Discrete Element Method

Scientific Conference (2022, December 09)

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

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

Rate Splitting Multiple Access for Cognitive Radio GEO-LEO Co-Existing Satellite Networks

Scientific Conference (2022, December 07)

Low Earth orbit (LEO) satellite communication has drawn particular attention recently due to its high data rate services and low round-trip latency. It is low-cost to launch and can provide global ... [more ▼]

Low Earth orbit (LEO) satellite communication has drawn particular attention recently due to its high data rate services and low round-trip latency. It is low-cost to launch and can provide global coverage. However, the spectrum scarcity might be one of the critical challenges in the growth of LEO satellites, impacting severe restrictions on the development of ground-space integrated networks. To address this issue, we propose rate splitting multiple access (RSMA) for cognitive radio (CR) enabled nongeostationary orbit (GEO)-LEO coexisting satellite network. In particular, this work aims to maximize the system's sum rate by simultaneously optimizing the power allocation and subcarrier beam assignment of LEO satellite communication while restricting the interference temperature to GEO satellite users. The problem of sum rate maximization is formulated as non-convex and a Global optimal solution is challenging to obtain. Therefore, we first employ the successive convex approximation technique to reduce the complexity and make the problem more tractable. Then for the power allocation, we exploit Karush–Kuhn–Tucker (KKT) condition and adopt an efficient algorithm based on the greedy approach for subcarrier beam assignment. We also propose two suboptimal schemes with fixed power allocation and random subcarrier beam assignment. [less ▲]

Dynamic Beam-Layout Design for MEO High Throughput Satellite Systems

Scientific Conference (2022, December 04)

We propose a traffic-oriented beam-layout optimization framework for a medium Earth orbit (MEO) high throughput satellite (HTS) system. The designed beam-layout plans have the objective of dynamic traffic ... [more ▼]

We propose a traffic-oriented beam-layout optimization framework for a medium Earth orbit (MEO) high throughput satellite (HTS) system. The designed beam-layout plans have the objective of dynamic traffic load balancing with minimal radio resource management. We model and evaluate the high directivity and the high reconfigurability capabilities of next-generation HTS systems that are equipped with a processing power on board. The resulting payload flexibility is compared numerically against the on-ground counterpart. Adequate key performance indicators, such as the Jain’s fairness index, the load distribution gap and optimization convergence time, are used to benchmark the system against state-of-the-art solutions. Results show that a dynamic HTS in MEO is capable of efficiently attaining high quality load balancing performance under realistic spatiotemporally varying traffic demands. [less ▲]

The Legality of EU Sanctions under International Investment Agreements

Scientific Conference (2022, December 02)

Optimizing Computational and Communication Resources for MEC Network Empowered UAV-RIS Communication

Scientific Conference (2022, December)

With the technological evolution and new applications, user equipment (UEs) has become a vital part of our lives. However, limited computational capabilities and finite battery life bottleneck the ... [more ▼]

With the technological evolution and new applications, user equipment (UEs) has become a vital part of our lives. However, limited computational capabilities and finite battery life bottleneck the performance of computationally demanding applications. A practical solution to enhance the quality of experience (QoE) is to offload the extensive computation to the mobile edge cloud (MEC). Moreover, the network’s performance can be further improved by deploying an unmanned aerial vehicle (UAV) integrated with intelligent reflective surfaces (IRS): an effective alternative to massive antenna systems to enhance the signal quality and suppress interference. In this work, the MEC network architecture is assisted by UAV-IRS to provide computational services to the UEs. To do so, a cost minimization problem in terms of computing time and hovering energy consumption is formulated. Furthermore, to achieve an efficient solution to a formulated challenging problem, the original optimization problem is decoupled into sub-problems using the block-coordinate decent method. Moreover, numerical results are compared to baseline schemes to determine the effectiveness of the proposed scheme. Simulation results demonstrate that the optimal allocation of local computational resources results in minimizing tasks’ computational time and hovering energy consumption. [less ▲]

Centering Europe and Othering the Rest: The Impacts of the EU Corporate Sustainability Due Diligence Directive on the Global South

Scientific Conference (2022, November 29)

Internships in Times of Crisis: Collaborative production of instructional videos at a distance

Scientific Conference (2022, November 24)

The Bachelor in Educational Sciences (BScE) at the University of Luxembourg offers a thorough and demanding teacher training program that combines academic and practical knowledge. As in many other ... [more ▼]

The Bachelor in Educational Sciences (BScE) at the University of Luxembourg offers a thorough and demanding teacher training program that combines academic and practical knowledge. As in many other initial teacher training programs, internships are a key part of each semester in the BScE. In the face of the COVID-19 health crisis, this essential part of our teacher training program could not be maintained. Indeed, the schools were closed, and the pupils were taught at a distance by their teachers. We therefore had to quickly innovate and set up alternative learning activities that best met the objectives of the internships. We thus asked our students to design and produce educational videos, in dyads, for the country's schools. The aim was to enable our students to develop the necessary skills to produce such learning resources and to make them available to schools via the Internet. We will describe, analyse and evaluate the scheme and the videos that were produced. We will also discuss possible lessons learned that might lead to adaptations in our training program. [less ▲]

Attitudes, Preconceptions and Practices in Conversational AI Design

Scientific Conference (2022, November 23)

Forschungsergebnisse und Forschungslücken zu Mehrsprachigkeit in der non-formalen Bildung in Luxemburg

Scientific Conference (2022, November 17)

The crucial role of language in mathematical development

Scientific Conference (2022, November 17)

Basic mathematics skills build on nonverbal number sense But these innate non-verbal skills are insufficient to develop symbolic exact number concepts and to learn arithmetic. Language development allows ... [more ▼]

Basic mathematics skills build on nonverbal number sense But these innate non-verbal skills are insufficient to develop symbolic exact number concepts and to learn arithmetic. Language development allows the acquisition of number words and math vocabulary, crucial for developing basic exact number concepts and arithmetic skills. This presentations highlights five key aspects on how language influences mathematical development. First, language is a building block for basic math skills. Second, number naming systems affect number transcoding. Third, multilingual students calculate better in the language in which they have learned numbers. Forth, children's home language influences their mathematics achievement. And finally, the mastery of the language of instruction has a strong impact on mathematics achievement. The implication of these key aspects are discussed with regard to education and instruction in schools. [less ▲]

Tradition - Zukunft - Bedürfnisse. Luxemburgische Blasmusik

Scientific Conference (2022, November 12)

Fairness as seen by students - a differentiated look at perceived assessment fairness by 7th and 9th graders in Luxembourg

Scientific Conference (2022, November 10)

Assessment is probably the central factor in every educational biography: On the one hand, through direct consequences for school career decisions, on the other hand, through repercussions on each ... [more ▼]

Assessment is probably the central factor in every educational biography: On the one hand, through direct consequences for school career decisions, on the other hand, through repercussions on each student’s self-concept in the respective subject, for one's own work behavior and the perception of institutional fairness in general. A crucial factor is the subjective, perceived fairness of assessment, which has been shown to influence students' satisfaction, motivation, and attitudes toward learning (Chory-Assad, 2002; Wendorf & Alexander, 2005). The current study examines how Luxembourgish students experience fairness of assessment on the basis of representative samples of the 7iéme (N > 700 students) and 9iéme/ 5iéme (N > 2200, 35% of the total cohort) and gives a first insight into the connection with school interest and self-concept. Special attention is given to the heterogeneity of the Luxembourgish student population: the extent to which language background, socioeconomic status, and gender are related to these perceptions of fairness will be analyzed. Data was collected as part of the nationwide Épreuves standardisées in fall 2021 using the Fairness Barometer (Sonnleitner & Kovacs, 2020) - a standardized instrument to measure informational and procedural fairness in student assessment. The analyses are theoretically based on Classroom Justice Theory and educational psychology (Chory-Assad and Paulsel, 2004; Chory, 2007; Duplaga & Astani, 2010) and utilize latent variable models (SEM) to study the complex interplay between perceived assessment practices and students’ school-related motivational factors. The insights offered by this study are internationally unique in their scope and provide a first glimpse on fairness perceptions of groups of Luxembourgish students in known disadvantaged situations. Results aim to sensitize especially active teachers and educators to the central importance of assessment in schools and offer some concrete advice how to improve it. References: Chory, R. M. (2007). Enhancing student perceptions of fairness: the relationship between instructor credibility and classroom justice. Commun. Educ. 56, 89–105. doi: 10.1080/03634520600994300 Chory-Assad, R. M., and Paulsel, M. L. (2004). Classroom justice: student aggression and resistance as reactions to perceived unfairness. Commun. Educ. 53, 253–273. doi: 10.1080/0363452042000265189 Chory-Assad, R. M. (2002). Classroom justice: perceptions of fairness as a predictor of student motivation, learning, and aggression. Commun. Q. 50, 58–77. doi: 10.1080/01463370209385646 Duplaga, E. A., and Astani, M. (2010). An exploratory study of student perceptions of which classroom policies are fairest. Decision Sci. J. Innov. Educ. 8, 9–33. doi: 10.1111/j.1540-4609.2009.00241.x Sonnleitner, P., & Kovacs, C. (2020, February). Differences between students’ and teachers’ fairness perceptions: Exploring the potential of a self-administered questionnaire to improve teachers’ assessment practices. In Frontiers in Education (Vol. 5, p. 17). Frontiers Media SA. Wendorf, C. A., and Alexander, S. (2005). The influence of individual- and class-level fairness-related perceptions on student satisfaction. Contemp. Educ. Psychol. 30, 190–206. doi: 10.1016/j.cedpsych.2004.07.003 [less ▲]

Implementation of a large-scale functional vision screener in early childhood at a national level

Scientific Conference (2022, November 10)

Functional vision refers to the way in which an individual uses visual skills and abilities to perform everyday tasks. Limitations on the functional use of vision can interfere with school achievements if ... [more ▼]

Functional vision refers to the way in which an individual uses visual skills and abilities to perform everyday tasks. Limitations on the functional use of vision can interfere with school achievements if left undetected. Early detection is thus key to offer appropriate aids to avoid a negative impact on learning processes. To screen for functional vision impairments at a national level, we developed a set of items measuring visual skills that can be administered in a classroom setting to be included in the yearly school monitoring tests ‘ÉpStan’ in grade 1. Children identified as being at risk will be followed by the Centre pour le Développement des compétences relatives à la Vue (CDV, MENJE). Based on a theoretical model of visual perceptual processing (Humphreys and Riddoch, 1987), we developed 35 items that were pretested. The same first graders (n = 1034) were administered group tests with the newly developed items and existing standardized individual tests (by CDV clinicians). Based on the clinical outcome of the CDV, the items which best predicted functional vision impairments were selected to be implemented in the Luxembourgish school monitoring in grade 1, together with a validated short parent questionnaire (Gorrie et al., 2019). This talk will focus on the development of the screener and on the characteristics of the children with functional vision impairments. [less ▲]

School Segregation in Primary and Secondary Education in Luxembourg: Track Placement and Academic Achievement

Scientific Conference (2022, November 09)

Known as a highly stratified education system with early tracking (similar to Dutch, German, Austrian, and German-speaking Swiss systems), Luxembourg features additional properties that add to its ... [more ▼]

Known as a highly stratified education system with early tracking (similar to Dutch, German, Austrian, and German-speaking Swiss systems), Luxembourg features additional properties that add to its complexity in the educational realm (Backes & Hadjar, 2017). It is a simultaneously multilingual system that also has the largest share of students born outside of Luxembourg or parents born abroad. While most migrants come from within Europe, they frequently come from either a particularly high or low socio-economic background. It has been scientifically established that the educational inequalities in Luxembourg are driven mostly by social origin and immigration/language background. Gender is another critical dimension of disadvantage; for example, boys are less motivated to obtain higher education than girls (Hadjar, Scharf, & Hascher, 2021). In addition, gender often intersects with other factors such as immigrant background in shaping disadvantages. However, evidence shows that – beyond individual background characteristics – schools’ social composition also perpetuates inequalities in student achievement (Martins & Veiga, 2010). Therefore, we focus on the role of school-level segregation on student’s academic outcomes over time using data of a longitudinal cohort from the School Monitoring Programme (Éprueve Standardisée (ÉpStan)) with 5097 students in Grade 3 observed in 2013 and later in Grade 9 observed in 2019 (regular pathways) and 2020 and 2021 (irregular pathways, i.e., class repetitions). School segregation is an aggregate measure of the proportion of students who belong to low socio-economic background and the proportion of students born abroad and/or do not speak instruction language at home. Our contribution aims to provide insights into the following questions: 1. Does school-level segregation in primary education (G3) predict student’s track placement in secondary education? 2. Does school-level segregation in primary education (G3) predict student’s math and German achievement in secondary education (G9)? 3. How strongly are achievement outcomes in G9 correlated with within- and between-track segregation in G9? The findings will serve as a complementary base for tailored policy making with respect to the long-term impact of school composition for teaching and learning, especially within a tracked school system. References Becker, S., & Hadjar, A. (2017). Educational trajectories through secondary education in Luxembourg: How does permeability affect educational inequalities? Schweizerische Zeitschrift Für Bildungswissenschaften, 39(3), 437–460. https://doi.org/10.25656/01:16659 Hadjar, A., Scharf, J., & Hascher, T. (2021). Who aspires to higher education? Axes of inequality, values of education and higher education aspirations in secondary schools in Luxembourg and the Swiss Canton of Bern. European Journal of Education, 56(1), 9–26. https://doi.org/10.1111/ejed.12435 Martins, L., & Veiga, P. (2010). Do inequalities in parents’ education play an important role in PISA students’ mathematics achievement test score disparities? Economics of Education Review, 29(6), 1016–1033. https://doi.org/10.1016/j.econedurev.2010.05.001 [less ▲]

Lie superalgebras of Krichever-Novikov type and their central extensions

Scientific Conference (2022, November 02)

Development of a test battery to diagnose specific learning disorder in mathematics in a multilingual education context

Scientific Conference (2022, November)

Validation and Psychometric Analysis of 32 cognitive item models spanning Grades 1 to 7 in the mathematical domain of numbers & operations

Scientific Conference (2022, November)

Today’s educational field has a tremendous hunger for valid and psychometrically sound items to reliably track and model students’ learning processes. Educational large-scale assessments, formative ... [more ▼]

Today’s educational field has a tremendous hunger for valid and psychometrically sound items to reliably track and model students’ learning processes. Educational large-scale assessments, formative classroom assessment, and lately, digital learning platforms require a constant stream of high-quality, and unbiased items. However, traditional development of test items ties up a significant amount of time from subject matter experts, pedagogues and psychometricians and might not be suited anymore to nowadays demands. Salvation is sought in automatic item generation (AIG) which provides the possibility of generating multiple items within a short period of time based on the development of cognitively sound item templates by using algorithms (Gierl & Haladyna, 2013; Gierl et al., 2015). The present study psychometrically analyses 35 cognitive item models that were developed by a team of national subject matter experts and psychometricians and then used for algorithmically producing items for the mathematical domain of numbers & shapes for Grades 1, 3, 5, and 7 of the Luxembourgish school system. Each item model was administered in 6 experimentally varied versions to investigate the impact of a) the context the mathematical problem was presented in, and b) problem characteristics which cognitive psychology identified to influence the problem solving process. Based on samples from Grade 1 (n = 5963), Grade 3 (n = 5527), Grade 5 (n = 5291), and Grade 7 (n = 3018) collected within the annual Épreuves standardisées, this design allows for evaluating whether psychometric characteristics of produced items per model are a) stable, b) can be predicted by problem characteristics, and c) are unbiased towards subgroups of students (known to be disadvantaged in the Luxembourgish school system). After item calibration using the 1-PL model, each cognitive model was analyzed in-depth by descriptive comparisons of resulting IRT parameters, and the estimation of manipulated problem characteristics’ impact on item difficulty by using the linear logistic test model (LLTM, Fischer, 1972). Results are truly promising and show negligible effects of different problem contexts on item difficulty and reasonably stable effects of altered problem characteristics. Thus, the majority of developed cognitive models could be used to generate a huge number of items (> 10.000.000) for the domain of numbers & operations with known psychometric properties without the need for expensive field-trials. We end with discussing lessons learned from item difficulty prediction per model and highlighting differences between the Grades. References: Fischer, G. H. (1973). The linear logistic test model as an instrument in educational research. Acta Psychologica, 36, 359-374. Gierl, M. J., & Haladyna, T. M. (Eds.). (2013). Automatic item generation: Theory and practice. New York, NY: Routledge. Gierl, M. J., Lai, H., Hogan, J., & Matovinovic, D. (2015). A Method for Generating Educational Test Items That Are Aligned to the Common Core State Standards. Journal of Applied Testing Technology, 16(1), 1–18. [less ▲]

MaaS modelling: a review of factors, customers’ profiles, choices and business models

Scientific Conference (2022, November)

Mobility-as-a-Service (MaaS) is regarded as one of the emerging solutions to offer integrated, seamless, and flexible multi-modal mobility services as an alternative to privately owned mobility resources ... [more ▼]

Mobility-as-a-Service (MaaS) is regarded as one of the emerging solutions to offer integrated, seamless, and flexible multi-modal mobility services as an alternative to privately owned mobility resources. MaaS gathers collective services such as public transport, shared solutions and other types of new mobility (e.g., on-demand ride services) and ancillary services (e.g., discounted parking) in bundles, accessed via monthly subscriptions. The key distinction between this system and traditional multi-modal systems managed by independent service providers is that payment for services is done through a single digital platform. MaaS is expected to change the way users will choose their modes of transport to reach their daily activities, and how service providers will generate profits, cooperate, and compete. From a wider perspective, MaaS is expected to favour a decline in car ownership and foster sustainable mobility, especially if the services increase the efficiency and utilisation of mass transit. To that aim, it is critical to obtain a thorough grasp of feasible and sustainable business models that suit the diverse needs of customers as well as the diverse and often competing objectives of service providers. In contrast, traditional transportation planning models typically assess solutions in a limited period of time (i.e., the peak hour) and use different simplifying assumptions (e.g., single trip-based choices, no interaction between service providers). This paper aims to provide a general modelling framework relating all main actors in the MaaS ecosystem and identify and discuss all factors that are considered relevant to define customers’ profiles and business models based on a comprehensive review of the literature. Gaps and challenges from the current studies are highlighted and future research directions are recommended. [less ▲]

AUSLEGUNG eines BIOMECHANISCHEN TESTSTANDES für das BECKEN einschließlich der MUSKELKRÄFTE des GANGZYKLUS

Scientific Conference (2022, October 28)

Impacting the computerization and Digitalization in Luxembourg: the case of teachers and education

Scientific Conference (2022, October 21)

“Challenge accepted”. The many sources to catch the history of virality and memes

Scientific Conference (2022, October 20)

Gifs and memes (Kaplan and Nova, 2016), “buzz” on the Web and social networks are inherent to digital cultures since the very first steps of the Web (i.e., Godwin’s Law, Dancing babies, Hamster Dance, cf ... [more ▼]

Gifs and memes (Kaplan and Nova, 2016), “buzz” on the Web and social networks are inherent to digital cultures since the very first steps of the Web (i.e., Godwin’s Law, Dancing babies, Hamster Dance, cf. McGrath, 2019). Virality has developed and changed over time, may it be related to forms (macro images, videos, etc.) and platforms (YouTube, 4Chan, Twitter, TikTok, etc.), audiences, curation and dissemination (with features encouraging spreadability within social platforms), etc., while relying on some patterns that were identified by Shifman (2014), Milner (2018), Jenkins (2009) and others. However, history and diachronic approaches still remain underrepresented in studies of online virality, although Finn Brunton’s Spam, Jason Eppink’s visual history of gifs (2014), or the Memes entry in The Sage Handbook of Web History (McGrath, 2019) can be mentioned. Historicizing virality through times, spaces and platforms is at the heart of the Hivi project at C2DH, University of Luxembourg (https://hivi.uni.lu). While starting to historicize these “Internet phenomena”, may it be Numa Numa Guy, Leave Britney Alone, Grumpy Cat, the Harlem Shake, Distracted Boyfriends, etc., challenges related to sources become more and more obvious: researchers have to deal with ephemerality as well as data overload, with several spaces of heritagization on the live and archived web, with gaps, silences and noises, issues of searchability in web archives, etc. This presentation focused on a case study, the Harlem Shake, to first demonstrate the variety of sources and spaces (physical and digital) that may be used to retrieve and rebuild this phenomenon (i.e., press, audiovisual content, archived web in several institutions, live web and platforms, etc.). It then presented the challenges related to this kind of reconstruction that is also strongly intertwining vernacular and commercial cultures; sound, video, textual contents; local as well as international spaces, etc. [less ▲]

Co-Organiser: Voices from the War – Path to Peace: Ukrainian and International Insights

Scientific Conference (2022, October 20)

Introductory Words of Conference: Voices from the War – Path to Peace: Ukrainian and international insights

Scientific Conference (2022, October 20)

Let’s talk about web archiving … three institutions, many possibilities

Scientific Conference (2022, October 18)

This presentation focused on three oral interviews I conducted during the COVID crisis, respectively with the BnL (Bibliothèque nationale du Luxembourg, Els, 2020) in Luxembourg and with INA (Institut ... [more ▼]

This presentation focused on three oral interviews I conducted during the COVID crisis, respectively with the BnL (Bibliothèque nationale du Luxembourg, Els, 2020) in Luxembourg and with INA (Institut national de l’audiovisuel, Schafer, 2020b) and BnF (Bibliothèque nationale de France, Gebeil et al., 2020) in France, to document their web archiving practices and choices during the pandemic. Oral histories not only document the collections and often hidden practices of crawling, selecting, curating and preserving data. They also provide a lot of information on living collections, on the challenges at stake and on human participation in this process. It also enlightens values and governance of web archives and web archiving practices (Schafer and Winters, 2021). Moreover, documenting web archiving is necessary for the current and future work of researchers and may help them to better understand their datasets, the representativeness of collections, bias and limits as well as the strengths of these web archives. Our presentation first compared the practices in the three institutions we selected as case studies for this presentation, in terms of perimeters, curation, stakeholders, targets - INA being a specific case as it focused more precisely on Twitter and retrieved data from the Twitter API, while the BnL and BnF targeted websites more widely (and some social networks but in a less systematic way). We also explained how these oral histories may help to better understand the shaping of web archives. We finally gave several concrete examples of the usefulness of this material for researchers who conduct research on web archives, and more specifically on the COVID crisis, in terms of transnational approaches, and silences and noises in web archives (Brügger, 2018), etc. [less ▲]

Keynote by panel on Looking ahead: after web (archives)?

Scientific Conference (2022, October 18)

On the (alleged) disappearance of repair since the 1970s

Scientific Conference (2022, October 14)

Nvidia Omniverse for Active Space Debris Removal Missions, an Overview

Scientific Conference (2022, October 13)

Earth orbits have an increasingly worrying space debris pollution problem caused by millions of human-made objects left in space. These are becoming a hazard for current and future space missions. Many ... [more ▼]

Earth orbits have an increasingly worrying space debris pollution problem caused by millions of human-made objects left in space. These are becoming a hazard for current and future space missions. Many solutions to deal with space debris problems have been proposed, including Active Space Debris Removal (ASDR) methods. In this thriving field, various technologies are under development, among them, systems based on tethers, nets, lasers, or robotic arms can be found. However, testing such systems on earth is challenging, recreating space-like conditions, such as accurate contact dynamics under microgravity, is particularly difficult. Nonetheless, it is of paramount importance to offer testing environments for clean space technologies, as space is unforgiving, and space devices must go through thorough evaluation processes to ensure peak efficiency. The HELEN project aims at fulfilling this very need. Building on one of the most advanced simulation frameworks, it will provide photo-realistic rendering, an accurate physical simulation of the space environment, and eventually, through Hardware-In-the-Loop (HIL), simulation of microgravity in ground facilities. This project is the result of the collaboration between SpaceR (University of Luxembourg), and Spacety (Industry). This simulation will be used to test FlexeS, an ASDR capturing system, which is under development. In HELEN, the accuracy of the physics is particularly important, as FlexeS will be validated through simulated HIL scenarios. Hence, a lifelike depiction of the microgravity environment, as well as the collisions, is critical. Moreover, to intercept and grab the debris FlexeS will rely on computer vision algorithms, thus photo-realistic graphics, allowing for lifelike visualizations are required. Furthermore, for future HIL testing, the ROS bridge and real-time communication capacity are crucial to connect the virtual world with the Zero-G robotic facility of the University of Luxembourg. In such a manner, FlexeS will be visualized in the space surroundings while simultaneously undergoing hardware experiments. With all these constraints in mind, Nvidia's Issac Sim was selected to create on-orbit dynamic scenarios. It not only meets all the requirements above but also provides a variety of sensors. Consequently, HELEN is creating on-orbit simulations featuring a CubeSat embedded with FlexeS, and debris circling the Earth. The scenarios showcase the digital twin of the capturing system intercepting debris, corresponding to the approaching phase in ASDR missions. Visually speaking, the RTX render engine allows for photo-realistic image generation. Regarding the motion of these objects, force-based astrodynamics is implemented into the simulation following the gravitational equation. Faithful velocities, position, and contacts are inferred by Nvidia's physics engine, PhysX. Scaled real-life values are used for the mass, as well as the orbital velocity and altitude. Thus, accurate simulations of contact dynamics between the system and the debris can be achieved. In the future, using a ROS bridge, the simulation will be connected to the HIL testing system of the Zero-G facility, amounting to a wholesome ASDR testing framework. Overall, the realistic simulations created with Isaac Sim are promising for analyzing clean space technologies. They combine photo-realistic scenes, accurate physics, and in the future, a means to test real hardware systems. [less ▲]

Concept of an Active Debris Removal 2-step capturing system for small satellites in Low Earth Orbit

Scientific Conference (2022, October 12)

Space debris 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 human-related ... [more ▼]

Space debris 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 human-related space missions. Despite being extremely challenging, catching autonomously and harmlessly an uncooperative object tumbling at high velocity demand reliability, compliance, and robustness. Grasping an object in microgravity means having control during the impact, but also keeping the link between the chaser satellite and the debris secure enough to handle the deorbiting phase. Supposing that the GNC installed tackles the synchronization with the debris rotation, so that only a linear translation is necessary to capture, three main problems can occur. The first problem can occur at the impact between the servicer and the debris. Due to the motion-reaction law, the debris could be pushed away if the capturing system does not prevent that motion. Besides, a high stiffness of the system, added to an unexpected strong impact, could damage either the servicer and/or the debris, resulting in a mission failure. Moreover, the need for a secure attach is required to go-on with the deorbit phase without losing the debris. That’s why, thanks to the fruitful collaboration between industry and academia (Spacety Luxembourg - SpaceR research group at the University of Luxembourg), a cutting-edge concept of a two-step capturing mechanism is being designed. Data analysis of trackable objects in LEO reveals an abundant number of CubeSat-shaped satellites, that future constellations might also take advantage of. Consequently, the concept presented is focusing on capturing these, at their end of life. A first ‘soft capture’ ensures that the debris is received softly while dampening any vibrations generated. A gecko-inspired adhesive surface will first receive the debris, preventing it from being pushed away. The property of such dry adhesive is that they do not require a high preload to stick to the surface, while having a very strong adhesion. To absorb most of the vibrations or movements due to the first impact, a compliant mechanism will be integrated behind the adhesive part. To that extent, if the alignment is not perfect, the system has some degrees of freedom, so that no damage can be generated. This compliant and sticky system would prevent the first main two issues of capturing an uncooperative target in microgravity. Then, a ‘hard capture’ secures the debris so that it would be deorbited without being released on the way. This part of the system would either gently squeeze the debris, using controlled adhesive flexible arms, or encircle it, and would be designed in compliance of ESA guidelines for demise. A two-step capturing mechanism is here proposed, taking advantage of bio-inspired dry adhesive technology, and compliant mechanisms, while having ESA guidelines in mind. Bringing the advantage of removing a vast range of objects in orbit, it also allows a reliable capturing, removing risks of generating more debris. Later works would bring attention to architecture that would fit more than a box shape. [less ▲]

3D Modelling for AR and 3D printing in Teacher Training

Scientific Conference (2022, October 07)

School activities integrating students’ environments into teaching aim to develop skills and strategies to solve problems in real-world situations and can be useful in hybrid teaching. Such activities can ... [more ▼]

School activities integrating students’ environments into teaching aim to develop skills and strategies to solve problems in real-world situations and can be useful in hybrid teaching. Such activities can encourage and motivate exploring skills in Science, Technology, Engineering, Arts, and Mathematics (STEAM). Hybrid teaching usually uses technologies and connects virtual and physical worlds. We use technologies like 3D modelling for Augmented Reality (AR) or 3D printing with GeoGebra and created an exercise introducing them in a lecture for pre-service mathematics students. The exercise combines the possibility to introduce these technologies, can be used in hybrid teaching and connects to the Austrian mathematics curriculum. The exercise consists of 3D modelling mathematical mazes that can be explored using AR on handheld devices and can also be 3D printed. We used it in online, offline and hybrid scenarios with pre- and in-service teachers and will show resulting presentations of teacher projects. [less ▲]

Augmented Reality in primary education: New learning opportunities for students with learning difficulties in mathematics education

Scientific Conference (2022, October 06)

Although there are manifold connections between mathematics, foremost geometry, and the real-world (e.g., architecture, arts, functional objects), integration seldom happens in daily learning lessons in ... [more ▼]

Although there are manifold connections between mathematics, foremost geometry, and the real-world (e.g., architecture, arts, functional objects), integration seldom happens in daily learning lessons in mathematics primary education. Learning three-dimensional geometric shapes, for example, is mainly done in a two-dimensional setting using textbooks instead of three-dimensional settings using technology or didactical material. This circumstance, however, makes it far more difficult for students with learning difficulties in mathematics to understand mathematical properties, recognize shapes in the real world, and understand the possibilities of modulating shapes. Students with learning difficulties learn efficient strategies to apply mathematics to their environment when shapes and connections are visualized with Augmented Reality within the real world. Based on several experiences and studies, we will present and discuss learning mathematics with Augmented Reality in primary education for students with learning difficulties. [less ▲]

L'espace frontalier franco-luxembourgeois vu depuis le Luxembourg

Scientific Conference (2022, October 02)

Non-Coherent Massive MIMO Integration in Satellite Communication

Scientific Conference (2022, October)

Massive Multiple Input-Multiple Output (mMIMO) technique has been considered an efficient standard to improve the transmission rate significantly for the following wireless communication systems, such as ... [more ▼]

Massive Multiple Input-Multiple Output (mMIMO) technique has been considered an efficient standard to improve the transmission rate significantly for the following wireless communication systems, such as 5G and beyond. However, implementing this technology has been facing a critical issue of acquiring much channel state information. Primarily, this problem becomes more criticising in the integrated satellite and terrestrial networks (3GPP-Release 15) due to the countable high transmission delay. To deal with this challenging problem, the mMIMO-empowered non-coherent technique can be a promising solution. To our best knowledge, this paper is the first work considering employing the non-coherent mMIMO in satellite communication systems. This work aims to analyse the challenges and opportunities emerging with this integration. Moreover, we identified the issues in this conjunction. The preliminary results presented in this work show that the performance measured in bit error rate (BER) and the number of antennas are not far from that required for terrestrial links. Furthermore, thanks to mMIMO in conjunction with the non-coherent approach, we can work in a low signal-to-noise ratio (SNR) regime, which is an excellent advantage for satellite links. [less ▲]

VARIABILITY-DRIVEN DESIGN CONFIGURATOR OF SPACE SYSTEMS TO SUPPORT DECISION-MAKERS

Scientific Conference (2022, October)

Enabling Elements of Simulations Digital Twins and its Applicability for Information Superiority in Defence Domain

Scientific Conference (2022, September 29)

The emerging concept of digital twins is the key enabler for modelling and simulations needs of any future-ready entity. Digital twins enable rapid transformation of requirements into capabilities at much ... [more ▼]

The emerging concept of digital twins is the key enabler for modelling and simulations needs of any future-ready entity. Digital twins enable rapid transformation of requirements into capabilities at much lower costs, compared to conventional methods, through enhancement of modularity and scalability. Elements of a modelling and simulations digital twin are discussed in this paper. These capabilities include, but are not limited to, surrogate modelling, optimization, parallelization, high performance computing, cloud architecture design, etc. These concepts are relevant for the integration of modelling and simulations technologies into a single interface digital twin for rapid prototyping and qualification of engineering systems. Use of these emerging technologies leads to significantly less simulation computation time (reduced from hours/days to seconds or even micro-seconds) compared to the conventional methods. Ease-of-collaboration with all stakeholders, reduced testing time, minimal on-site infrastructure requirements are the key cost-reducing advantages found in this study. Applicability of such intelligent and online digital twins for information superiority to enhance cybersecurity and on-board threat assessment of space-based (defence) services is analysed. The use of these synchronized and interoperable capabilities mitigates both reversible and non-reversible physical and cyber threats to defence space infrastructure. [less ▲]