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Toutes les publications de l'ENAC en direct.
All ENAC publications.

[hal-02073283] Preconditioned P-ULA for Joint Deconvolution-Segmentation of Ultrasound Images - Extended Version

Publications ENAC - Saturday, 15 June 2019 - 03:26:43
Joint deconvolution and segmentation of ultrasound images is a challenging problem in medical imaging. By adopting a hierarchical Bayesian model, we propose an accelerated Markov chain Monte Carlo scheme where the tissue reflectivity function is sampled thanks to a recently introduced proximal unadjusted Langevin algorithm. This new approach is combined with a forward-backward step and a preconditioning strategy to accelerate the convergence, and with a method based on the majorization-minimization principle to solve the inner non-convex minimization problems. As demonstrated in numerical experiments conducted on both simulated and in vivo ultrasound images, the proposed...

[hal-02149924] Software defined network based architecture to improve security in a swarm of drones

Publications ENAC - Tuesday, 11 June 2019 - 11:59:40
With the trend of developing more and more applications for Unmanned Aerial Vehicles (UAV), several research projects have considered new missions where single UAVs are replaced by swarms of drones. Although today regulations do not take into account such scenarios, implementation of an efficient security policy appears mandatory before operating a swarm of drones in open spaces. Consequently, this paper introduces an architecture for providing security features through the use of software defined network (SDN) technologies. To validate our approach, we compare the routing performance of our architecture with a classical solution based on the AODV routing protocol and...

[hal-02145644] Time-based Consensus

Publications ENAC - Friday, 7 June 2019 - 13:55:50
Reaching consensus is fundamental in distributed computing. For each execution of a consensus algorithm, there is no difference between the proposed values by different nodes with respect to their proposed times. By presenting a realistic application scenario related to distributed asynchronous mobile robots in dynamic environments, we argue some safety-critical, real-time systems require reaching consensus on the newest proposed values when the old proposed values may not be valid anymore. Afterward, we formulate a new type of consensus problem called time-based consensus, which requires to take into account the times of proposed values. Finally, to tackle such a...

[hal-02132979] A Continuum of Interfaces to Engage Surgical Staff in Efficient Collaboration

Publications ENAC - Thursday, 6 June 2019 - 18:55:20
Large hospital surgical suites must combine high quality of care with an efficient management of operations. However, the diversity of procedures, staff, and patients present important challenges for staff collaboration. The complexity of flows between tasks and places, such as interconnections between pre-operation, post-operation and intensive care units, led previous research to address these issues separately using checklists, scheduling, or specialized human-computer interfaces. Approaches to treat the surgical suite as a whole entity have not been explored yet. Here, we build upon a cyber-physical system comprising an electronic whiteboard and different sensors...

[tel-02139581] Évitement de conflits aériens par une régulation subliminale en vitesse : modélisation & résolution via le contrôle optimal

Publications ENAC - Monday, 3 June 2019 - 18:38:14
À travers une approche de contrôle optimal, cette thèse de doctorat propose une étude des modèles et des techniques de résolution dans un domaine d'application propre à la gestion du trafic aérien. Motivés par la croissance des flux aériens d'une part, et les développements en théorie du contrôle optimal d'autre part, ces travaux portent sur l'analyse du problème d'évitement de conflits aériens. Cette étude permet le développement de nouvelles approches et algorithmes en vue d'aider les contrôleurs aériens dans leur tâche. Ainsi, dans le cadre du trafic aérien, afin de préserver des distances minimales de sécurité entre avions, lors de phases tactiques et de...

[hal-01722807] GPU based Computational Simulation of Aircraft Evacuation: Temporal and Spatial Analysis

Publications ENAC - Monday, 3 June 2019 - 12:49:27
he effectiveness of Aircraft Emergency Evacuation plays a vital role in the safety of the passengers on board an Aircraft, in case of Emergency landing. In this paper, the implementation and development of a Cellular Automata (CA) based simulator which can be used to simulate the Aircraft Evacuation process is presented. Given the seat-map of the Aircraft, number of passengers, passenger feature distribution and number of functional exits, the simulator can calculate the approximate time of Evacuation. For computational implementation, a bi-dimensional as well as uni-dimensional grid which represents the 2D Aircraft seat-map and an agent which control the passenger...

[hal-02138628] Pricing schemes for air traffic services through multi-level approaches

Publications ENAC - Wednesday, 29 May 2019 - 18:11:40
This article addresses the problem of air traffic service (ATS) pricing over a domestic air transportation system with either private or public ATS providers. In both cases, to take into account feedback effects on the air transportation market, it is considered that the adopted pricing approaches can be formulated through optimization problems where an imbedded optimization problem is concerned with the supply of air transportation (offered seat capacity and tariffs for each connection). Under mild assumptions in both situations the whole problem can be reformulated as a mathematical program with linear objective function and quadratic constraints. A numerical...

[hal-02136768] Predictive Distribution of the Mass and Speed Profile to Improve Aircraft Climb Prediction

Publications ENAC - Wednesday, 29 May 2019 - 12:14:27
Ground-based aircraft trajectory prediction is a major concern in air traffic control and management. A safe and efficient prediction is a prerequisite to the implementation of new automated tools. In current operations, trajectory prediction is computed using a physical model. It models the forces acting on the aircraft to predict the successive points of the future trajectory. Using such a model requires knowledge of the aircraft state (mass) and aircraft intent (thrust law, speed intent). Most of this information is not available to ground-based systems. Focusing on the climb phase, we train neural networks to predict some of the unknown point-mass model parameters....

[hal-02090426] Departure Management with Robust Gate Allocation

Publications ENAC - Tuesday, 28 May 2019 - 18:33:21
The Airport Collaborative Decision Making (A-CDM) concept yields concrete and promising solutions for airports, in terms of traffic punctuality and predictability, with possible delay, noise and pollution reduction. A key feature of A-CDM is the Departure Management (DMAN): runway takeoff sequences can be anticipated such that a significant part of the delay can be shifted at the gate, engines off, without penalizing the remaining traffic. During this process, an increase in the gate occupancy for delayed departures is unavoidable, therefore the airport layout must provide enough gates and their allocation must be robust enough w.r.t. departures delay. In this paper, we...

[hal-02135040] Extended Aircraft Arrival Management under Uncertainty: A Computational Study

Publications ENAC - Tuesday, 28 May 2019 - 11:45:00
The arrival manager operational horizon, in Europe, is foreseen to be extended up to 500 n miles around destination airports. In this context, arrivals need to be sequenced and scheduled a few hours before landing, when uncertainty is still significant. A computational study, based on a two-stage stochastic program, is presented and discussed to address the arrival sequencing and scheduling problem under uncertainty. This preliminary study focuses on a single initial approach fix and a single runway. Different problem characteristics, optimization parameters, as well as fast solution methods for real-time implementation are analyzed in order to evaluate the viability of...
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