HAL-Université de Bretagne Occidentale
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Uncoordinated RIS-Aided Uplink IoT Cell-Free Massive MIMO-NOMA Systems
No full textInternational audienceCell-free massive MIMO (CF-mMIMO) has emerged as a promising architecture for beyond 5G networks, offering enhanced coverage and spectral efficiency through distributed antenna arrays. This paper proposes a novel framework integrating reconfigurable intelligent surfaces (RIS) and non-orthogonal multiple access (NOMA) in CF-mMIMO for uplink grant-free internet of things (IoT) scenarios. In such scenarios, devices transmit without prior coordination with a central unit, which increases the risk of multi-user interference. NOMA is thus introduced to address this challenge through successive interference cancellation (SIC). IoT devices autonomously select subbands using the multi-armed bandit (MAB) framework. Based on the devices subband choices, RIS angles are configured so as to satisfy the quality-of-service (QoS) requirements of all devices while leveraging NOMA SIC ordering. The resulting optimization problem becomes infeasible in many practical scenarios. To address these cases, we introduce: (1) a classification approach to proactively identify certain infeasible constraints, and (2) an iterative constraint relaxation method to improve the likelihood of finding feasible solutions. Additionally, a dynamic SIC reordering strategy is proposed to further enhance system performance. An enhanced upper confidence bound (UCB) algorithm is also introduced where, upon convergence, devices maintain their subband choices to minimize unnecessary explorations and optimizations. Simulation results demonstrate that our framework achieves higher success rates while reducing the required optimizations compared to baseline approaches
Winter Dynamics of Phytoplankton and Micronutrients in the Southern Ocean
No full textInternational audienceCombined observations of phytoplankton abundance, community structure, and trace metals in winter are scarce but crucial for understanding Southern Ocean biogeochemistry. This study provides the first early winter insights of phytoplankton-micronutrient dynamics in the Indian sector of the Southern Ocean. Depth-resolved measurements of chlorophyll-a, phytoplankton composition, and micronutrients iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and cadmium (Cd) reveal low phytoplankton abundance (0.27-0.08 μg L-1 chlorophyll-a) and variable phytoplankton-micronutrient dynamics between the zones. In the Subtropical Zone, cyanobacteria, and haptophytes dominated, driven by higher temperatures, limiting macronutrients, Fe and Zn, and shaped Co and Mn through biological uptake. In the Subantarctic and Polar Frontal Zones, cyanobacteria contributions declined but continued to play a key role in shaping Co dynamics. Diatoms were limited by Mn, Zn, and silicic acid, enabling the dominance of prasinophytes. Other groups such as coccolithophores may have benefitted from the ability to substitute Zn for Cd and contributed to the formation of particulate Cd. Coccolithophores along with Phaeocystis also contributed to particulate Cd in the Antarctic Zone, where Fe and Mn limited the abundance of the dominating diatoms. Diatoms, in turn, strongly contributed to particulate Zn. This perspective on phytoplankton-micronutrient relationships shows that despite their low productivity in the harsh low light wintertime Southern Ocean, phytoplankton continue to influence trace metal distribution and that there are strong phytoplankton group-specific associations with various essential metals, rather than Fe alone, that vary latitudinally
: Conférence invitée "Observer les représentations sociales de demain"
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Pour une cohérence intégrée de la pédagogie, du contenu et de la technologie dans les pratiques d'enseignement des "digital skills" en contexte universitaire
No full textInternational audienceThe teaching of digital skills constitutes one of the foundations for the development of pedagogical innovation and the facilitation of learning. However, the recent integration (2023-2024) of Digital Skills, as a module element relating to soft skills, implies the questioning of a set of pedagogical practices, professional gestures and social representations among teachers. The objective of this work is to identify efficient pedagogical practices to be integrated into the university curriculum inorder to better prepare students for academic requirements. Therefore, how do the pedagogical practices of teachers in Moroccan universities promote the development of digital skills among students? Based on the TPACK model and a qualitative survey conducted among teachers at the Ecole Normale Supérieure of Marrakesh, the results of this research show that the teaching of digital skills goes beyond mere technical mastery to be part of a set of skills: disciplinary, pedagogical and technological.L'enseignement des digital skills constitue l’un des socles de développement de l’innovation pédagogique et de la facilitation de l’apprentissage. Nonobstant, l’intégration récente (2023-2024) des Digital Skills, en tant qu’élément de module relevant des soft skills dans l’enseignement supérieur marocain, implique la remise en cause d’un ensemble de pratiques pédagogiques, de gestes professionnels et de représentations sociales chez les enseignants. L’objectif de ce travail est d’identifier les pratiques pédagogiques efficientes à intégrer dans le curriculum universitaire en vue d’une meilleure préparation des étudiants aux exigences académiques. Dès lors, comment les pratiques pédagogiques des enseignants au sein des universités marocaines favorisent le développement des digital skills chez les étudiants? En se basant sur le modèle TPACK et sur une enquête qualitative menée, auprès des enseignants, au sein de l’Ecole Normale Supérieure de Marrakech, les résultats de cette recherche montrent que l’enseignement des digital skills dépasse la seule maîtrise technique pour s’inscrire dans ensemble de compétences: disciplinaires, pédagogiques et technologiques
Hierarchical nanoengineered NiCo LDH@α-Fe2O3 heterostructures for optimised electrochemical capacitive performance
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Assessing the effects of three harmful microalgal species on spermatozoa and embryos of the king scallop Pecten maximus
No full textInternational audienceThe reproductive process plays a crucial role in the renewal of marine bivalve populations and represents an economic issue for exploited species, such as the king scallop Pecten maximus. However, environmental phenomena, such as harmful algal blooms (HAB), can affect key reproductive life stages, including gametes and embryos. This study examines the effects of exposure to three harmful microalgal species (Alexandrium minutum, Lingulodinium polyedra, and Pseudo-nitzschia australis) on spermatozoa and embryos of king scallops P. maximus. The physiological responses of spermatozoa were evaluated after exposure to low (LC) and high concentrations (HC) of each microalgal species. While none of the tested microalgal strains showed direct toxicity, oxidative stress was associated with HC of A. minutum, and morphological changes were observed after exposure to L. polyedra and P. australis. Embryos of P. maximus were also exposed to HC of the same three microalgae species and examined under a microscope after 4h, 24h, and 48h of exposure. Exposure to A. minutum hindered cell division of embryos within the first four hours of development, leading to complete embryo lethality at 24 hours. No significant changes in early development were noted during the initial 48 hours of exposure to L. polyedra and P. australis. These findings underscore the diverse effects of harmful microalgal species, emphasizing the need for targeted fishery and shellfishery management, both spatially and temporally, especially when bivalves and harmful algal bloom species potentially coincide during bivalve reproduction and recruitment
Large melt diversity at a mid-ocean ridge thermal low
No full textInternational audienceMid-ocean ridges serve as key sites for understanding the composition of the mantle, but extensive melting usually masks its lithological diversity. This study explores how cold mid-ocean ridge segments, such as the eastern Romanche ridge-transform intersection (ERRTI), provide unique insights into mantle heterogeneity. Here, a thick cold lithosphere faces the warm ridge segment efficiently cooling the ridge tip, thus reducing melting and mixing, and allowing distinct short-scale lithologies to be sampled. Our findings reveal a mosaic of mantle components with diverse geochemical and isotopic signatures, reflecting dynamic mantle processes over time. By examining these cold regimes, this research sheds light on the mantle’s compositional complexity and its evolution, offering a fresh perspective on lithospheric dynamics and melt generation in settings independent of hotspot influences
Former aux métiers de l'architecture : tout un projet !
No full textInternational audienceLes étudiants d’aujourd’hui ont des demandes de plus en plus fortes vis-à-vis des formations qu’ils reçoivent. Cela s’explique en partie par le fait qu’ils se sentent contraints par les attentes du monde du travail qui exige d’eux une opérationnalité quasi immédiate ; parce qu’ils n’arrivent pas tous à élaborer une vision claire de ce qu’ils savent ; et parce que les savoirs des disciplines universitaires sont si étendus qu’ils ont des difficultés à trouver les liens entre tous les savoirs qu’on leur transmet.Différentes recherches incitent à penser que l’élaboration d’un projet de formation peut contribuer à répondre à ces attentes. Un projet de formation correspond à l’élaboration collective d’une vision du diplômé précisant ce qui est exigible de l’étudiant en fin de formation du point de vue, d’une part des savoirs qu’il devra savoir mobiliser dans les situations qu’il va rencontrer après ses études en fonction de son projet, et d’autre part du profil de sortie (ce qui est attendu de lui en termes d’autonomie, d’éthique, etc.).Une des contraintes inhérente à l’élaboration du projet de formation réside dans le fait qu’il s’agit d’un travail collectif réalisé par une équipe pédagogique. Cette élaboration collective pose des questions spécifiques concernant notamment comment travailler ensemble ; comment inscrire ce travail collectif dans l’histoire à court ou moyen terme de l'équipe ; et comment impliquer les étudiants.L'intervention propose d’éclairer ces différents points
