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Programmer en OCaml pour et sur les calculatrices Numworks
No full textInternational audienceDans cet article, nous présentons le portage d'OMicroB, un environnement d'exécution pour le langage OCaml, sur les calculatrices graphiques programmables Numworks, aujourd'hui très présentes dans les collèges et lycées en France. Ce portage permet de programmer et compiler via un ordinateur des applications graphiques pour la calculatrice, comme un "jeu de la vie", mais aussi d'exécuter des interpréteurs pour d'autres noyaux de langages de programmation (Prolog, mini-ML). Enfin, nous décrivons l'implémentation d'une boucle d'interaction (REPL) basée sur l'interpréteur du projet CamlBoot vue comme un environnement de développement permettant d'écrire et d'exécuter des petits programmes OCaml directement sur la calculatrice
Predictive validity of cognitive abilities for air traffic controllers selection among proficient scientific candidates
No full textInternational audienceMost air traffic controllers (ATCO) are selected after high school graduation, partly based on cognitive abilities. On the contrary, French ATCO are selected after an intensive scientific post-secondary program without undergoing cognitive assessment. This study examines the potential incremental validity of cognitive predictors in ATCO training for such proficient applicants. Initial and unit training results were available for 414 and 277 ATCO students, respectively. All students took cognitive ability tests, encompassing visuospatial processing, quantitative knowledge, and work samples. We compared a baseline regression model with academic performance as sole predictor to an extended model with the addition of the cognitive abilities composite score. The R2 of the extended model increased significantly, by 0.04 (p < .001) and 0.06 (p < .001), respectively, for predicting practical initial and unit training outcome. In conclusion, even for scientific proficient candidates, cognitive assessment can enhance the success rate of ATCO training
Evaluating risk-based hazard corridors in air traffic controller decisions during space launch failures
No full textInternational audienceThe increasing frequency and diversity of space launch activities challenge the safety and reliability of current air traffic management systems. In this study, we present a risk-based hazard corridor methodology for managing air traffic during space launch failures. Our method combines a debris propagation model with a hazard corridor construction approach that estimates the risk posed by debris to aircraft. We evaluated the constructed risk-based hazard corridors using high-fidelity human-in-the-loop simulations. In our experiments, air traffic controllers managed two strategies of hazard corridors. The dynamic hazard corridor updated the boundary in real-time while the static hazard corridor remained fixed by consolidating the dynamic boundaries over the entire activation period until the last piece of debris fell. The results show that controllers maintained safety separation across all scenarios, although their real-time workload increased significantly during hazard corridor activation. Overall, the controllers’ perceived workload and situation awareness remained stable, implying that the task demands were acceptable for all the experimental runs. Efficiency measure results indicate that the dynamic hazard corridor can reduce extra flight distance and delays, thus minimizing operational disruption caused by space launch failures. We also found that more experienced controllers tend to choose more cautious and conservative rerouting strategies. These findings offer practical guidance for improving resilience in air and space management integration. Furthermore, our study provides a basis for modeling air traffic controller behavior under emergency conditions in a way that is more in line with the real world patterns
Assessing Spoofing Impact on GNSS Receivers : Carrier-to-Noise density Ratio (C/N0) Estimation
No full textInternational audienceIn the context of GNSS signal processing, the carrier-to-noise density ratio (C/N0) is a powerful metric for evaluating GNSS performance, analyzing interference effects, and monitoring reception quality. Although the modeling of C/N0 in the presence of interference has been extensively discussed in the literature, the specific impact of spoofing remains unexplored. In fact, due to the similar structure between authentic and spoofed signals, the latter directly interferes with the true signal and cannot be considered as an equivalent additional and independent noise source. This paper investigates the impact of spoofing on both true and estimated C/N0 and proposes analytical expressions for their biases in the presence of spoofing. It reveals situations where the correlator output becomes non-ergodic, inducing divergence between the true and estimated values, as well as significant C/N0 degradation. Additionally, there is a high dependence on the receiver architecture (estimation method) and spoofing geometry. Finally, beyond GNSS spoofing applications, this study highlights the effect of non-ergodicity on estimation and underscores the importance of studying estimation under non-ergodic conditions.</div
Geographic Population Modeling for the Simulation of Satellite Constellations
No full textInternational audienceThis paper introduces a data-driven model for generating synthetic satellite users based on population and geographical factors. The model applies the logarithmic opinion pool to combine complementary perspectives on user distribution, such as population density and rural predominance. This principled aggregation captures realistic spatial disparities in connectivity and improves the representativeness of satellite constellation simulations. The approach supports the development of adaptive non-terrestrial network (NTN) strategies aligned with both orbital topology and terrestrial demand
Does increasing human impact across the holocene result in simplification of vegetation composition and diversity across Europe? A pollen-based spatio-temporal approach
No full textInternational audienceLand use and climate change are the primary drivers of current biodiversity loss, but have had different impacts on biodiversity across the Holocene epoch. To enhance our understanding of current changes in diversity and its impact on ecosystem functions, knowledge of long-term interactions between vegetation diversity, land use change, and climatic change is crucial. Grid-cell estimates of quantified regional vegetation cover (RVest) based on pollen data from 1607 sites across Europe, transformed using the REVEALS (Regional Vegetation Estimates from Large Sites) model, have been used to explore spatiotemporal changes in vegetation and regional diversity during the Holocene (25 time windows covering the period from 11.7 ka cal BP to present). Space-time constrained clustering of the RVests identified six dominant vegetation types (VTs): Mediterranean vegetation, open vegetation, Abies-Fagus forest, broadleaved mixed forest, coniferous mixed forest, Betula woodland, whose spatial extent changes over the Holocene. The study explored REVEALS α-diversity (richness of taxa, richness ofabundant taxa, and evenness) within each grid cell as well as spatial REVEALS β-diversity (spatial variations in composition within one time frame) and turnover (temporal variation in composition within one grid cell) within each vegetation type. Changes in location, size, taxa composition, and REVEALS diversity of the vegetation types characterised four phases during the Holocene. The first (pioneer: 11.7–9.2 ka cal BP) and second (summer-green forest: 9.2 ka to 5.2 ka cal BP) phases generally showed higher REVEALS β-diversity and lower REVEALS evenness. The third phase (mixed semi-natural forest: 5.2 ka to 1.7 ka cal BP) is characterised by expansion of open vegetation and reflects increased human impact on the environment caused by increasing use of land for agricultural production. The final phase (from 1.7 ka cal BP) saw rapid transformations: open vegetation not only expanded, but also shifted in composition, with major increases in cereals and other anthropogenic indicators. This signals a clear intensification of land-use impact over the last two millennia. Across central Europe, vegetation became increasingly homogenised, dominated by a few widespread species. As a result, both REVEALS evenness and spatial β-diversity plummeted—marking a profound loss of ecological complexity.In short, human-driven landscape openness did not simply reshape the vegetation—it rewrote the rules of diversity across the continent
Traffic complexity measurement via collective dynamics analysis of arrival traffic patterns
No full textInternational audienceThe measurement of arrival traffic operational complexity is essential in supporting decisionmaking processes, as it provides valuable insights into arrival traffic operations. Many studies have concentrated on measuring subjective complexity, achieving significant success in their respective areas; however, subjective complexity measurement requires the involvement of professional controllers, leading to higher costs during implementation. To reduce the cost for measuring subjective complexity, this paper analysed the collective dynamics of arrival traffic in both horizontal and vertical dimensions, and summarized several traffic patterns through a coupled analysis. Subsequently, this paper found that the complexity can be reflected in the evolution of arrival traffic patterns and developed a metric to measure the subjective complexity based on the evolution of patterns. A case study, focusing on the arrival traffic operations within the terminal area of Guangzhou Baiyun airport, is conducted to validate the proposed metric.</div
Air Traffic Management and Communication over ATN/IPS for Future Datalink Communication
No full textInternational audienceThe growing demand for air traffic presents challenges in air traffic management, making seamless gate-to-gate communication essential. Traditional radio frequency communication faces limitations such as weather dependency and frequency restrictions. To address these issues, data link communications have gained importance, using VHF channels, satellite systems, and ATN/IPS-based networks. This study introduces the ATMACA (Air Traffic Management and Communication Over ATN/IPS) protocol, an advanced context management framework for ATN/IPS, designed to enhance aviation communications. ATMACA integrates instant messaging and software-defined nodes to improve connectivity, session continuity, and mobility management across networks and devices. It ensures seamless user interaction, reduces pilot workload, and enhances flight safety through automated Air Traffic Control (ATC) sector handoff in Controller-Pilot Data Link Communications (CPDLC) and Data Link Initiation Capability (DLIC) applications. Another key innovation of the ATMACA framework is Green Route Operations (GRO), which enables real-time trajectory prediction and optimization
On Selecting a Routing Protocol for Nanosatellite Swarm Networks
No full textAccepté pour publication dans IEEE VTC-Spring 2025 (Oslo Norvège)International audienceRouting in nanosatellites swarms presents distinct challenges, including variable node availability, constrained bandwidth, and dynamic topology. Strategies like delay-tolerant networking (DTN) can be advantageous, as they adapt to intermittent connectivity by storing and forwarding data when connections are established. Moreover, geographic routing protocols that exploit satellite positions can improve efficiency, while machine learning approaches may optimize routing decisions based on changing network conditions. What about hybrid approaches that may combine some of these methods? Basically, the crucial question is where to begin. The primary challenge for nanosatellites network designers is to determine which routing strategies to test prior to deployment. Given the vast number of existing routing protocols, testing all of them is not possible. This problem motivates the present study, which share the authors' experiences on selecting the most suitable routing algorithms for a given nanosatellites swarm. In particular, the study reports how the use of graph theory metrics helps in restricting the set of routing algorithms to be considered for network characterization and protocol selection