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Strategic Path Change Maneuvers for Weather Obstacle Avoidance in Aviation
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Integrated air-rail scheduling: A branch-and-price approach for adaptive passenger-centric planning
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Speaking of Safety: Drone-Based Voice Communication for Industry
No full textInternational audienceEnsuring the safety of personnel at large industrial sites is a significant challenge. Misunderstandings and increased safety risks are related to communication, as traditional non-targeted alerts like sirens are often ineffective. To address this, we propose a drone-based system that uses voice interaction to deliver timely and targeted safety advisories. This paper presents a multi-stage, user-centered study, beginning with formative interviews with security and safety managers and culminating in an on-site evaluative study with personnel at two biomass power plants. Through our study, we identify key design insights for creating a drone that is perceived as an official, authoritative, and non-threatening entity. We provide design guidance for using sound and movement to signal intent, creating a voice persona that balances authority with clarity, and designing interaction flows to manage confusion and non-compliance. The results demonstrate the system's potential not only to enhance safety compliance, but also to mitigate interpersonal confrontation. First, we provide an empirically-grounded understanding of contextual safety challenges, which informs a set of design principles for intelligible and socially acceptable voice advisories from drones. Second, we present results from an in-situ evaluation of a working prototype that demonstrates its effectiveness in a real-world setting
Downlink optimization for direct-to-satellite IoT with LEO satellites and LoRaWAN
No full textInternational audiencenetworks a b s t r a c t Direct-to-satellite communication systems for the Internet of Things, particularly those based on low-Earth-orbit satellite constellations, are emerging as a transformative solution to achieve global connectivity. However, ensuring efficient and reliable downlink communication from satellites to ground-based IoT devices remains a significant challenge due to intermittent satellite visibility, short contact durations, limited bandwidth, device energy constraints, and high network density. Unlike prior studies that primarily focus on uplink optimization, this work proposes a downlink-aware optimization framework that integrates satellite dynamics, LoRaWAN MAC constraints, and energy-aware scheduling. The framework accounts for physical-layer limitations, satellite visibility modeling, time-slot feasibility, and realistic system parameters consistent with LEO satellite operations. Simulations demonstrate that the proposed downlink-aware optimization framework improves the packet delivery ratio from 0.41 (achieved under random scheduling) to 0.96, while reducing the average energy consumption per successful transmission by approximately 55 %. These results highlight the efficiency of the proposed NSGA-II-based scheduling approach and provide an initial pattern that points toward potential scalability, compared to conventional non-optimized methods, demonstrating its promise for next-generation satellite-enabled IoT networks.</div
An improved optimization algorithm for solving arrival aircraft scheduling problem in the Terminal Maneuvering Area
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Real-Time aircraft conflict detection and trajectory optimisation for emergency weather management in terminal manoeuvring areas
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Unlocking Resilience and Load Balancing: Toward Hop-By-Hop Routing for LEO Mega-Constellations
No full textInternational audienceWe propose a fully decentralized, adaptive routing system that exploits the dynamic topology of Walker Delta Low Earth Orbit (LEO) constellations to achieve efficient traffic distribution and improved reliability without requiring global link-state information. The system addresses scalability challenges in mega-constellations, where congestion, limited ground infrastructure, and uneven user distribution degrade service quality in high-demand regions. Although inter-satellite links provide diverse routing paths, the lack of multibeam support in some terminals complicates routing and can increase path length during cross-plane communication. Our evaluation of a Hop-by-Hop based strategy in Walker Delta constellations shows that it achieves performance comparable to optimal congestion minimization algorithms and outperforms source-routing methods, while maintaining near-minimal hop counts for low-latency communication
Enhancing airline multimarket competition analysis with a pairwise competitive intensity index based on weighted Jaccard index
No full textInternational audienceWe advance the measurement of multimarket contact (MMC) in the airline competition literature by introducing a flight frequency weighted Jaccard index. Unlike conventional MMC measures that rely on binary market presence, our proposed index captures both market overlap and supply strategic similarity through flight frequency. Current airline competition research can be divided into market-based metrics (e.g., HHI, CR), which overlook relationships among firms, and airline-based metrics, of which MMC is the most prominent but only considers market overlap. Our index bridges this gap and describes the pairwise competitive intensity among airlines within a specific geographic region. We interpret the use of the index through three applications: unsupervised clustering of airline business models, detection of market shocks, and tracking changes in competitive relationships during disruptions. Our work will allow researchers to refine previous MMC related studies. This work provides policymakers with tools to monitor real-time market competition and may better inform competition regulation design. For airlines, they can leverage the index to identify rivals with the same or different business models, measure their competitive intensity, and choose their competition strategy accordingly
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
Cramér-Rao Bounds for Feedback-Based Synchronization Architectures
No full textInternational audienceSynchronization is essential in modern communication systems to ensure accurate demodulation and time-frequency alignment. Two main architectures are employed: feedforward and feedback. While the theoretical bounds for feedforward synchronizers have been extensively studied in the literature, the performance analysis of feedback synchronizers remains relatively unexplored. This paper derives the Cramér-Rao Bound (CRB) for feedback synchronization in the data-aided (DA) case, applicable to general communication signal structures and arbitrary modulation schemes. The analysis involves formulating a dynamic signal model under parameter evolution assumptions and deriving an iterative expression for the CRB. Additionally, a new expression for the feedforward CRB is presented, which facilitates its computation, interpretation, and the comparison between the two approaches. Results show that, while both approaches exhibit similar performance at high signal-to-noise ratios (SNR), feedback synchronization yields improved accuracy, particularly when the parameter evolution model is accurately specified.</div