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CDR Compass : analyse et modélisation des impacts de la stratégie Numérique Responsable
No full textThis thesis addresses the need for structured decision-making in the context of Corporate Digital Responsibility (CDR) by developing and operationalising a novel methodological framework — CDR Compass. Grounded in a Design Science Research approach, the work responds to growing academic and practical needs to navigate the social and ecological complexities introduced by digital transformation within organisational contexts, particularly in the absence of robust empirical data and established evaluation frameworks.The CDR Compass is a decision-making tool designed to support organisations in structuring their CDR strategies. Comprising three sequential phases—problem framing, forward-looking evaluation, and forward-looking analysis—it integrates Multiple Criteria Decision Analysis and expert-based methods to assess the potential impacts of CDR actions against context-sensitive socio-environmental criteria. The tool is iteratively developed and validated through scenario-based testing, expert consultations, and application in real-world cases.Key contributions include a structured approach to the forward-looking impact evaluation and analysis of the CDR strategy, a CDR maturity model, and empirical demonstrations illustrating the use of the CDR Compass in both artificial and real-world contexts. The thesis expands current understandings of digital sustainability and positions CDR as an operational bridge between corporate responsibility and digitalisation, concluding with practical and theoretical insights for enhancing decision-making and advocating for responsible digitalisation that maintains a safe and just space for humanity.Cette thèse aborde la nécessité d'une prise de décision structurée dans le contexte de la Responsabilité Numérique des Entreprises (RNE) en développant et en opérationnalisant un cadre méthodologique - le « CDR Compass ». Fondée sur une approche de recherche en sciences de la conception (Design Science Research), cette recherche répond à des besoins académiques et pratiques croissants visant à appréhender les complexités sociales et écologiques introduites par la transformation numérique au sein des organisations, en particulier en l'absence de données empiriques robustes et de cadres d'évaluation établis. Le CDR Compass est un outil d'aide à la décision conçu pour accompagner les organisations dans la structuration de leurs stratégies RNE. Composé de trois phases séquentielles - cadrage du problème, évaluation prospective, et analyse prospective - il intègre l'Analyse de Décision Multicritère (MCDA) et des méthodes fondées sur l'expertise afin d'évaluer les impacts potentiels des actions RNE selon des critères socio-environnementaux sensibles au contexte. L'outil est développé et validé de manière itérative à travers des tests basés sur des scénarios, des consultations d'experts et d'applications à des cas réels. Les principales contributions incluent une démarche structurée pour l'évaluation et l'analyse prospective des impacts des stratégies RNE, un modèle de maturité RNE, ainsi que des démonstrations empiriques illustrant l'usage du CDR Compass dans des contextes réels. Cette thèse enrichit la compréhension actuelle du numérique responsable et positionne la RNE comme un pont opérationnel entre la responsabilité des entreprises et la transformation numérique, en concluant par des perspectives pratiques et théoriques destinées à améliorer la prise de décision et à promouvoir une transformation numérique responsable, garantissant un espace sûr et équitable pour l'humanité
Living among blacksmiths ? Preliminary archaeological results of the 2023 campaign at the Kpeta 2 settlement (Benin)
No full textInternational audienc
Maritime Monitoring through LoRaWAN: Resilient Decentralised Mesh Networks for Enhanced Data Transmission
No full textInternational audienceResilient communication networks from ocean-deployed buoys are crucial for maritime applications. However, wireless data transmission in these environments faces significant challenges due to limited buoy battery capacity, harsh weather conditions, and potential interference from maritime vessels. LoRaWAN technology, known for its low power consumption and long-range communication capabilities, presents a promising solution. Nevertheless, the standard LoRaWAN framework lacks native support for multi-hop routing, which is essential for enhancing network efficiency by relaying data between buoys. This paper introduces two novel multi-hop routing protocols designed for resilient LoRaWAN mesh networks in maritime environments. The first, Opportunistic Smart Routing over a Decentralised LoRaWAN Mesh (OSR-DLM), employs a cross-layer design with a hybrid routing strategy and balanced metric selection. The second, Beacon-Forwarding LoRaWAN with Channel-Aware Path Selection (BF-LoRaCAPS), maintains continuous device awareness using a scheduling mechanism and integrates the OSR-DLM strategy for further optimisation. We evaluate these protocols through extensive simulations that model the detrimental effects of severe weather on data transmission, validated by analysing varied parameter settings in massive Maritime of Things (MoT) scenarios. Key performance metrics, including packet delivery ratio, end-to-end latency, throughput, and traffic intensity for each hop-ratio, are analysed. The results show the superiority of both OSR-DLM and BF-LoRaCAPS over conventional Geographic Routing Protocol (GRP) variants under realistic marine channel conditions. Notably, BF-LoRaCAPS exhibits superior network coverage and resilience, outperforming both OSR-DLM and GRP variants, albeit with slightly increased latency
Type I and Type II Hot Corrosion of Ni-Based Alloys Without an Incubation Period
No full textInternational audienceA series of results obtained with different types of Ni-based alloys for turbine discs and blades, and exposed to various (Type I and Type II) hot-corrosion conditions (air, air + 150-400 ppm SO2) is reported. Both the continuous mass-change measurements and the characterizations of alloys after a brief exposure at high temperature with sulphate deposits, in air or in air + SO2 (g) atmospheres, clearly demonstrate fast oxidation rates from the earliest time of exposure in the presence of sulphate deposits, i.e. accelerated oxidation. In situ SEM observations also support these findings. It clearly appears that hot corrosion often starts with a direct reaction involving the metallic substrate, the gaseous species and the sulphate deposits, i.e., that it occurs in most cases without any incubation period. The results can therefore be of interest for the development of complementary selection procedures for alloys and coatings
Diversity of sea trout marine migration routes in the English Channel
No full textInternational audienceAnadromous brown trout ( Salmo trutta ), also called sea trout, migrate from freshwater nursery and spawning grounds to the sea to maximise their growth and fecundity. Sea trout may undertake this marine migration several times in their life cycle, repeatedly facing significant natural or anthropogenic pressures on their migration path. Using data storage tags, we reveal for the first time the migratory paths and behaviour of post-spawning sea trout from three rivers (two in England and one in France) draining into the English Channel. Our results show a longitudinal gradient in sea trout migratory timing, with individuals from the western population reaching the sea earlier and residing longer in the marine environment than the eastern populations. Overall, sea trout dispersed widely within the English Channel, and each population used distinct marine areas up to the Celtic and North Seas. Within populations, individuals followed one or two directional migration routes that enabled us to identify seven main migratory corridors. Most sea trout spent 80% of their marine phase within 45 km of the shore, with a greater tendency to utilise waters further away from the shoreline at the midpoint of their marine migration. Individual tag data also show that having prior migratory experience influences horizontal behaviours. Finally, individuals from France were geolocated in English waters and vice versa, underpinning the necessity for international management of sea trout around the English Channel
Typologie géomorphologique des systèmes falaise–estran : application aux côtes rocheuses de Charente-Maritime
No full textInternational audienceLes falaises rocheuses de Charente-Maritime s’étendent sur 60 km et sont principalement entaillées dans des formations calcaires et marno-calcaires du Jurassique supérieur et du Crétacé supérieur. Elles sont associées à des estrans de diverses natures, incluant des plateformes rocheuses, des accumulations de galets, de sable ou de vase. La morphologie des falaises, à l’échelle départementale, est hétérogène, avec des variations significatives de hauteurs, pentes et composition lithologique. Cette diversité complique l’analyse des dynamiques côtières et limite les approches comparatives. Ce travail propose une méthode visant à élaborer une typologie des falaises de Charente-Maritime, en tenant compte du système « estran-falaise ».Une première tentative de typologie morphologique construite sur l’étude du front de falaise, basée sur des critères lithologiques et topographiques et une classification à dire d’expert a été réalisée par Jean-Baptiste (2021). Les limites de ce travail ont été montrées (Béranger et al., 2024). Afin d’améliorer cette typologie, cette étude propose une méthodologie qui prend en compte le système « estran-falaise ». Cette approche se base sur une acquisition multi-data (terrain, télédétection, SIG). Son originalité réside dans l’intégration des descripteurs de l’estran, un facteur clé dans la dissipation de l’énergie des vagues et potentiellement dans l’érosion des falaises (Earlie et al., 2018 ; Vann Jones et al., 2018 ; Krier-Mariani et al., 2023 ; Matsumoto et al., 2024). L’estran est caractérisé par sa nature (rocheux, sableux, vaseux) et sa topographie (largeur, pente, morphologie). La falaise est décrite par la prise en compte de trois groupes d’indicateurs : la topographie (hauteur, pente, orientation, sous-cavage), la lithologie (matériaux, formations allochtones et autochtones du sommet de falaise), la structure (fracturations, pendage et orientation des stratigraphies). Ces groupes d’indicateurs, composants le système « estran-falaise », sont impliqués dans la morphodynamique des côtes rocheuses à falaise (Payot et al., 2015).Le linéaire côtier à falaises de Charente-Maritime est segmenté à partir d’imagerie aérienne oblique, en fonction des discontinuités morphologiques (failles, lithologie, hauteur) Cela a permis d’identifier plus d’une centaine de segments « falaise-estran ». Cette segmentation est validée sur le terrain, puis des points de collecte sont générés en SIG pour optimiser l’acquisition des données. Des logs litho-stratigraphiques sont levés, et un indice GSI (Hoek et Marinos, 2000) est attribué à chaque point d’observation. Les autres indicateurs sont collectés sur le terrain ou par télédétection et SIG, puis transposés aux segments homogènes. La classification repose sur une Analyse Factorielle de Données Mixtes (AFDM) pour réduire la dimensionnalité des données. Une Classification Ascendante Hiérarchique (CAH) permet ensuite de regrouper les segments en classes homogènes. Cette typologie des systèmes « estran-falaise » constituera une base d’analyse des dynamiques érosives et des mouvements gravitaires à l’échelle départementale
Modelling the distribution of rare and data-poor diadromous fish at sea for protected area management
No full textABSTRACT Anthropogenic pressures have resulted in declines in diadromous fish. Many diadromous fish which were commercially important are now threatened and protected. Little is known about their marine life history phases, and no observation-based Species Distribution Model exists for this group of species at sea. Yet, fisheries dependent and independent data could provide new insights into the distribution of diadromous fish at sea. We collated a database of 168 904 hauls from fisheries observer bycatch data and scientific fisheries surveys, from eastern Atlantic and Mediterranean waters. The distribution of eleven rare and data-poor diadromous fish (shads, lampreys, salmonids, the European eel, the thinlip mullet, smelt and the European flounder) were modelled. A Bayesian site occupancy model, that incorporates imperfect detection to account for repeat detections and non-detections, the non-random nature of fishing gear type and spatial autocorrelation was used. From the model outputs, we explored bycatch risk and the role of MPAs, required under the Marine Strategy Framework Directive and Habitat Directive and assessed. Diadromous fish were observed within relatively shallow coastal areas. Species specific gear bycatch trends were observed. Core distribution areas corresponded to their known water basin presence, indicating connectivity with their freshwater habitats. Numerous Habitat Directive Marine Protected Areas were found to be of relevance. Given the coastal distribution of these species, they are exposed to higher anthropogenic pressures from both terrestrial and marine environments. Risk of bycatch at sea for most species appears to be low. Nonetheless, for threatened individuals, even a small amount of bycatch may impact their populations, especially since misreporting is likely to be high. Differences in catchability between gears highlight potential benefits of limiting access of certain gears within protected areas to reduce bycatch
Introducción. Las ciudades en el sur de la península ibérica y el norte de África en la Antigüedad tardía (ss.III-VIII)
No full textInternational audienc
Global tracking of marine megafauna space use reveals how to achieve conservation targets
No full textInternational audienceThe recent Kunming-Montreal Global Biodiversity Framework (GBF) sets ambitious goals but no clear pathway for how zero loss of important biodiversity areas and halting human-induced extinction of threatened species will be achieved. We assembled a multi-taxa tracking dataset (11 million geopositions from 15,845 tracked individuals across 121 species) to provide a global assessment of space use of highly mobile marine megafauna, showing that 63% of the area that they cover is used 80% of the time as important migratory corridors or residence areas. The GBF 30% threshold (Target 3) will be insufficient for marine megafauna’s effective conservation, leaving important areas exposed to major anthropogenic threats. Coupling area protection with mitigation strategies (e.g., fishing regulation, wildlife-traffic separation) will be essential to reach international goals and conserve biodiversity
TRACE4PM: Trace Related Analysis and ClustEring for Process Modeling of Users’ Interactions in Information Systems
No full textInternational audienceThe rapid growth in information systems usage has highlighted the importance of modeling user behavior to improve usability, deliver personalized recommendations, and refine system design. User interactions with these systems generate rich datasets of event data crucial for such analyses. Process mining plays a pivotal role in modeling these behaviors, often complemented by trace clustering techniques that help manage the complexity of user interactions. In this context, we introduce TRACE4PM, an automated pipeline encapsulated within an API explicitly designed to model user behaviors in information systems using process mining techniques focusing on trace clustering techniques. The platform offers services, including parsing, tagging, clustering, and process modeling of the event data, all based on state-of-the-art Process mining techniques. This API-based solution promotes ease of integration and usage, enabling developers and researchers to use the API platform without requiring them to delve into technical aspects or requirements. To demonstrate the real-world applicability of TRACE4PM, we developed a Moodle plugin that collects and analyzes Moodle logs to cluster and model student interaction traces, successfully extracting helpful learning models from the educational data. Furthermore, researchers and educators feedback validated TRACE4PM’s and the Moodle plugin’s efficiency, applicability, and educational utility, highlighting their potential for broader adoption and refinement