Last 7 days
Bookmark and Share    
Full Text
Peer Reviewed
See detailNear surface defects: Cause of deficit between internal and external open-circuit voltage in solar cells
Sood, Mohit UL; Urbanaik, Aleksander; Kameni Boumenou, Christian UL et al

in Progress in Photovoltaics (2021)

Interface recombination in a complex multilayered thin-film solar structure causes a disparity between the internal open-circuit voltage (VOC,in), measured by photoluminescence, and the external open ... [more ▼]

Interface recombination in a complex multilayered thin-film solar structure causes a disparity between the internal open-circuit voltage (VOC,in), measured by photoluminescence, and the external open-circuit voltage (VOC,ex), that is, a VOC deficit. Aspirations to reach higher VOC,ex values require a comprehensive knowledge of the connection between VOC deficit and interface recombination. Here, a near-surface defect model is developed for copper indium di-selenide solar cells grown under Cu-excess conditions. These cell show the typical signatures of interface recombination: a strong disparity between VOC,in and VOC,ex, and extrapolation of the temperature dependent q·VOC,ex to a value below the bandgap energy. Yet, these cells do not suffer from reduced interface bandgap or from Fermi-level pinning. The model presented is based on experimental analysis of admittance and deep-level transient spectroscopy, which show the signature of an acceptor defect. Numerical simulations using the near-surface defects model show the signatures of interface recombination without the need for a reduced interface bandgap or Fermi-level pinning. These findings demonstrate that the VOC,in measurements alone can be inconclusive and might conceal the information on interface recombination pathways, establishing the need for complementary techniques like temperature dependent current–voltage measurements to identify the cause of interface recombination in the devices. [less ▲]

Detailed reference viewed: 46 (7 UL)
Full Text
Peer Reviewed
See detailParental migration and psychological well-being of children. Longitudinal evidence from Ghana
Raturi, Radhika; Cebotari, Victor UL

E-print/Working paper (2021)

Detailed reference viewed: 32 (0 UL)
Full Text
Peer Reviewed
See detailRecension d' European Drama and Performance Studies n° 16 : « Percevoir et transmettre le spectacle vivant »
Deregnoncourt, Marine UL

Scientific Conference (2021, October 11)

Cette recension, divisée en trois temps, va suivre les différents points de vue adoptés par les participants au seizième numéro de la revue European Drama and Performance Studies, consacré à la perception ... [more ▼]

Cette recension, divisée en trois temps, va suivre les différents points de vue adoptés par les participants au seizième numéro de la revue European Drama and Performance Studies, consacré à la perception et à la transmission du spectacle vivant et dirigé par Françoise Gomez et Daniel Loayza : 1. Le regard du chercheur (Florence Naugrette, Julia Gros de Gasquet et Patrice Pavis) ; 2. Le regard du praticien de la scène (Emmanuel Demarcy-Mota et Don Kent) ; 3. L’archivage mémoriel (Sandrine Siméon et Daniel Loayza). [less ▲]

Detailed reference viewed: 57 (1 UL)
Full Text
Peer Reviewed
See detailEl Estado de Bienestar de la 4T y La Tercera Vía
Huitrón García, Patricia Manuela; Cebotari, Victor UL; Rodríguez Rosario, David Gustavo

Article for general public (2021)

Detailed reference viewed: 169 (4 UL)
Full Text
Peer Reviewed
See detailAre Firms Withdrawing From Basic Research? An Analysis of Firm-level Publication Behaviour in Germany
Krieger, Bastian UL; Blind, Knut; Gruber, Sonia et al

in Scientometrics (2021), 126

Detailed reference viewed: 18 (3 UL)
Full Text
Peer Reviewed
See detailPerformance assessment of the relative gravimeter Scintrex CG-6
Francis, Olivier UL

in Journal of Geodesy (2021), 95:116

The new-generation relative gravimeter Scintrex CG6 is put on the test bench: Its performance is compared to its predecessor, the Scintrex-CG5. A CG5 Scintrex and a CG6 Scintrex were both submitted to the ... [more ▼]

The new-generation relative gravimeter Scintrex CG6 is put on the test bench: Its performance is compared to its predecessor, the Scintrex-CG5. A CG5 Scintrex and a CG6 Scintrex were both submitted to the same rigorous tests, which have been developed in recent years to highlight some defects of the CG5. The results show that the CG6 always performs better than the CG5. For instance, the instrumental drift is 5 times smaller for the CG6 than for the CG5. In the tidal bands, the noise level of the CG6 is 3 times lower than of the one of the CG5. We confirmed the tilt susceptibility of the CG5 and found that the CG6 is barely affected by long duration tilts before taking measurements. Unlike the CG5, the CG6 measurements are not influenced by external temperature variations. Overall, the CG6 provides more precise and stable gravity measurements compared to the CG5. [less ▲]

Detailed reference viewed: 57 (3 UL)
See detailPeut beaucoup mieux faire:Les stéréotypes de genre dans les manuels de l’enseignement fondamental
Quiqueret, Jérôme; Kerger, Sylvie UL

Article for general public (2021)

Detailed reference viewed: 14 (0 UL)
Full Text
See detailSpinning Functional Fibers: An Interplay of Rheology, Miscibility & Crosslinking
Vats, Shameek UL

Doctoral thesis (2021)

Wearable technology in general has increasingly gained interest in the last few decades and textile with incorporated functional component constitute one form of it. There are multiple ways to produce ... [more ▼]

Wearable technology in general has increasingly gained interest in the last few decades and textile with incorporated functional component constitute one form of it. There are multiple ways to produce polymer fibers on both laboratory and industrial scales, and one of them is core–sheath electrospinning, which is a powerful method for producing advanced composite fibers. Liquid crystals (LCs), are materials that readily exhibit optical response to fluctua- tions and change in their immediate environment. By incorporating LC within polymer fibers through electrospinning, it is possible to create responsive LC-polymer fiber mats. However, incorporating a functional core has proven challenging for certain combinations of materials. This thesis explores and addresses some of the concerns involved in the coaxial electrospinning of fibers incorporating LCs from several standpoints. Firstly, the effect of solvents on the electrospinning process was systematically studied. Fol- lowing this, an optimum viscosity with pure and mixed solvents for successful electrospinning was identified and uniform fibers with different solvent combinations was produced. Using the knowledge gained, core-sheath electrospinning with LC as the core was carried out. One of the key findings of this work, the identification of a suitable means to reduce the interfacial tension between the core and sheath fluid to prevent break up of the jet and produce uniformly filled fibers, while at the same time avoiding complete mixing between core and sheath. These findings can be applied to any combination of core and sheath materials and should appeal to a large community of researchers. Eventually, to achieve the durability of the LC-functionalized electrospun fiber mats for use in wearable technology, the sheath polymer of the fiber were crosslinked after spinning. The resultant crosslinked fibers were easily manipulated by hand and even fully immersed in water without dissolving and without losing their functional LC core. [less ▲]

Detailed reference viewed: 93 (8 UL)
Full Text
Peer Reviewed
See detailLeveraging High-Frequency Components for Deepfake Detection
Mejri, Nesryne UL; Papadopoulos, Konstantinos UL; Aouada, Djamila UL

in IEEE Workshop on Multimedia Signal Processing (2021)

In the past years, RGB-based deepfake detection has shown notable progress thanks to the development of effective deep neural networks. However, the performance of deepfake detectors remains primarily ... [more ▼]

In the past years, RGB-based deepfake detection has shown notable progress thanks to the development of effective deep neural networks. However, the performance of deepfake detectors remains primarily dependent on the quality of the forged content and the level of artifacts introduced by the forgery method. To detect these artifacts, it is often necessary to separate and analyze the frequency components of an image. In this context, we propose to utilize the high-frequency components of color images by introducing an end-to-end trainable module that (a) extracts features from high-frequency components and (b) fuses them with the features of the RGB input. The module not only exploits the high-frequency anomalies present in manipulated images but also can be used with most RGB-based deepfake detectors. Experimental results show that the proposed approach boosts the performance of state-of-the-art networks, such as XceptionNet and EfficientNet, on a challenging deepfake dataset. [less ▲]

Detailed reference viewed: 207 (58 UL)
Full Text
See detailCyborg, IA et société "cyborgisée" : l’avènement d’une société-ruche
Derian, Maxime UL

in Collectif (Ed.) Aux frontières de l'humain (2021)

If the cyborg remains a human - repaired, augmented or diminished -, the emergence of metaphorical or real figures such as the latter as well as hybrids, robots, drones and AIs, is perhaps the expression ... [more ▼]

If the cyborg remains a human - repaired, augmented or diminished -, the emergence of metaphorical or real figures such as the latter as well as hybrids, robots, drones and AIs, is perhaps the expression of an anthropological major shift. Indeed, beyond the question of the enhanced humanity, transhumanism and the possibility of posthumanism, it seems topical to ask whether it is not society itself that is in the process of becoming 'cyborgised' on a global scale. In such a case, rather than listing the anthropotechnical technologies (of human modification) that have appeared since the invention of computers, it seems appropriate to anticipate and attempt to understand the ethical, political, economic and social issues emblematic of these technologies. Hence the concept of the 'hive-society', used to describe this possible major break in history marked by the advent of an organisation that is above all administered by - and sometimes for - digital machines. [less ▲]

Detailed reference viewed: 81 (7 UL)
Full Text
Peer Reviewed
See detailMendelian randomization study of smoking, alcohol, and coffee drinking in relation to Parkinso's disease
Domenighetti, Cloe; Sugier, Pierre Emmanuel; Sreelatha, Ashwin Ashok Kumar et al

in Journal of Parkinson's Disease (2021)

Background:Previous studies showed that lifestyle behaviors (cigarette smoking, alcohol, coffee) are inversely associated with Parkinson’s disease (PD). The prodromal phase of PD raises the possibility ... [more ▼]

Background:Previous studies showed that lifestyle behaviors (cigarette smoking, alcohol, coffee) are inversely associated with Parkinson’s disease (PD). The prodromal phase of PD raises the possibility that these associations may be explained by reverse causation. Objective:To examine associations of lifestyle behaviors with PD using two-sample Mendelian randomisation (MR) and the potential for survival and incidence-prevalence biases. Methods:We used summary statistics from publicly available studies to estimate the association of genetic polymorphisms with lifestyle behaviors, and from Courage-PD (7,369 cases, 7,018 controls; European ancestry) to estimate the association of these variants with PD. We used the inverse-variance weighted method to compute odds ratios (ORIVW) of PD and 95%confidence intervals (CI). Significance was determined using a Bonferroni-corrected significance threshold (p = 0.017). Results:We found a significant inverse association between smoking initiation and PD (ORIVW per 1-SD increase in the prevalence of ever smoking = 0.74, 95%CI = 0.60–0.93, p = 0.009) without significant directional pleiotropy. Associations in participants ≤67 years old and cases with disease duration ≤7 years were of a similar size. No significant associations were observed for alcohol and coffee drinking. In reverse MR, genetic liability toward PD was not associated with smoking or coffee drinking but was positively associated with alcohol drinking. Conclusion:Our findings are in favor of an inverse association between smoking and PD that is not explained by reverse causation, confounding, and survival or incidence-prevalence biases. Genetic liability toward PD was positively associated with alcohol drinking. Conclusions on the association of alcohol and coffee drinking with PD are hampered by insufficient statistical power. [less ▲]

Detailed reference viewed: 30 (1 UL)
See detailAdvanced Characterizations of Silica Surface in Rubber Compounds by Solid-State Nuclear Magnetic Resonance Spectroscopy
Yan, Chuanyu UL

Doctoral thesis (2021)

This thesis details the development, validation, and application of advanced solid-state nuclear Magnetic resonance spectroscopy (NMR) techniques for the characterization of the silica surface in raw ... [more ▼]

This thesis details the development, validation, and application of advanced solid-state nuclear Magnetic resonance spectroscopy (NMR) techniques for the characterization of the silica surface in raw materials and in rubber compounds. The performance of the quantitative techniques (29Si DP-CPMG, SVD and 29Si multiCP) and qualitative techniques (29Si CP-CPMG and {1H-29Si}-1H MCPi) are investigated using model and close-to-real life samples. The insights gained from this study are useful for the surface-specific characterization of silica and could offer clues for similar topics. [less ▲]

Detailed reference viewed: 87 (12 UL)
See detailExploring the Past in Public: Recent Public History Exchanges in Southern Luxembourg
Harnoncourt, Julia UL; van de Maele, Jens UL

Scientific Conference (2021, October 07)

Detailed reference viewed: 35 (1 UL)
See detailL’UEBL et les relations belgo-luxembourgeoises au XXème siècle
Brüll, Christoph UL

Scientific Conference (2021, October 06)

Detailed reference viewed: 38 (0 UL)
See detailSix provocations for 6G
Schafer, Valerie UL

Scientific Conference (2021, October 06)

Detailed reference viewed: 17 (0 UL)
Full Text
See detailA Distributed Unmanned Aerial Vehicles Traffic Management System
Samir Labib, Nader UL

Doctoral thesis (2021)

The rapid adoption of Internet of Things (IoT) has encouraged the integration of new connected platforms such as Unmanned Aerial Vehicles (UAVs) to the ubiquitous network. UAVs promise a pragmatic ... [more ▼]

The rapid adoption of Internet of Things (IoT) has encouraged the integration of new connected platforms such as Unmanned Aerial Vehicles (UAVs) to the ubiquitous network. UAVs promise a pragmatic solution to the limitations of existing terrestrial IoT infrastructure as well as they bring new means of delivering services through a wide range of applications ranging from monitoring and surveillance to on-demand last-mile delivery and people transport. Owning to their potential, UAVs are expected to soon dominate the low-altitude airspace over populated cities. This introduces new research challenges such as the safe management of UAVs operation under high traffic demands. In response to this, industry proposed a handful of constructs for UAV Traffic Management (UTM), however due to their centralised approaches, they will inevitably face limitations in scalability and resilience with predicted traffic demands and advancement in UAV autonomy. In this context, the main objective of this work is to address the aforementioned problem by proposing a distributed UAV Traffic Management system (dUTM). This thesis, hence, investigates the validity of the above hypothesis by: (i) showing the performance insufficiency of centralised systems due to their inadequacy in efficiently optimising large UAV traffic, (ii) showing why a distributed system is favourable due to its characteristics of scalability and resilience, (iii) proposing a novel dUTM framework consisting of an airspace structure model, information exchange model and a traffic optimisation model that rely on distributed methods and approaches to intelligently handle highly dynamic and challenging traffic conditions. To this end, this manuscript contributes to scientific literature by proposing a novel way of structuring the uncontrolled, low-altitude airspace and introduces a model of the Class G airspace as a multi-weighted multilayer network of nodes and airways. Additionally the work presents a novel distributed multiobjective path planning algorithm incorporating a dynamic multi-criteria decision matrix allowing each UAV or agent to plan their path relying on local knowledge gained via digital stigmergy. The PhD thesis additionally contributes to existing state of the art by exploring the technical standardisation landscape and investigating synergies between research directions and standards developments, taking into consideration pressing inherit challenges of UAVs within IoT such as security, data protection and privacy. [less ▲]

Detailed reference viewed: 62 (7 UL)
Peer Reviewed
See detailCareer journeys of skilled migrants in Luxembourg: a qualitative exploration
Usanova, Ksenia UL

Scientific Conference (2021, October 05)

Detailed reference viewed: 47 (0 UL)
See detailAutomatic Analysis, Representation and Reconstruction of Textured 3D Human Scans
Saint, Alexandre Fabian A UL

Doctoral thesis (2021)

Various practical applications in computer vision are related to the human body. These involve representing and modelling the body shape, pose, clothing and appearance with mathematical and statistical ... [more ▼]

Various practical applications in computer vision are related to the human body. These involve representing and modelling the body shape, pose, clothing and appearance with mathematical and statistical tools requiring datasets of examples, representative of the variation in the data. Three-dimensional (3D) data is especially important as it allows to simulate the physical world directly, for example to analyse and lift ambiguities in other prevalent data modalities, such as images. However, existing datasets of 3D human scans show limitations in their size, diversity, quality or annotation. This reduces their applicability in tackling research questions around the 3D human body. Two particular applications of interest that remain unanswered are the estimation of body shape under clothing, and the completion of textured shape of missing or defective data. This thesis proposes three main contributions. First, 3DBodyTex, a dataset of 3D human scans, which complements alternative datasets with real scans, body and clothing scans, hundreds of subjects, high-resolution texture information, dense annotations and aligned body shapes under the clothing. The aim is to enable and facilitate new research possibilities with learning-based methods, in 3D or using derived modalities. Second, to build this dataset automatically from raw scans, multiple robust 3D processing methods are proposed. These involve pose estimation, pose fitting, tight body shape fitting, and body shape estimation under clothing. The proposed methods show competitive or improved results on existing benchmarks and new proposed benchmarks based on 3DBodyTex. In particular, an alternative method is proposed to estimate the body shape under clothing from a single scan. On independent benchmarks, it is competitive with, or better than, methods requiring a full time sequence of scans. Third, the task of shape and texture completion of 3D human scans is tackled. A new method is proposed that completes the shape and the texture sequentially, and automatically identifies the missing regions. In particular, partial convolutions are extended to texture images (UV maps) for inpainting the colour of a 3D scan using a convolutional neural network. A new benchmark, based on 3DBodyTex, is proposed for the evaluation. [less ▲]

Detailed reference viewed: 50 (6 UL)
Full Text
Peer Reviewed
See detailDigital Identities and Verifiable Credentials
Sedlmeir, Johannes UL; Smethurst, Reilly UL; Rieger, Alexander UL et al

in Business and Information Systems Engineering (2021), 63(5), 603-613

Public institutions and companies typically employ physical credentials (such as passports, social security cards, and employee badges) to identify individuals. Individuals can choose where to store their ... [more ▼]

Public institutions and companies typically employ physical credentials (such as passports, social security cards, and employee badges) to identify individuals. Individuals can choose where to store their physical credentials, and sometimes, they can decide to whom their credentials are disclosed. These familiar privileges inspired a new type of digital credential called a verifiable credential (VC). Similar to physical credentials, individuals can store their verifiable credentials in a so-called digital wallet on their mobile phone, on another edge device, or in the cloud, and they can use verifiable credentials for identification, authentication, and authorization. [less ▲]

Detailed reference viewed: 50 (1 UL)