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

[hal-01565168] Mental workload and neural efficiency quantified in the prefrontal cortex using fNIRS

Publications ENAC - Samedi, 22 juillet 2017 - 03:12:14
An improved understanding of how the brain allocates mental resources as a function of task difficulty is critical for enhancing human performance. Functional near infrared spectroscopy (fNIRS) is a fielddeployable optical brain monitoring technology that provides a direct measure of cerebral blood flow in response to cognitive activity. We found that fNIRS was sensitive to variations in task difficulty in both real-life (flight simulator) and laboratory settings (tests measuring executive functions), showing increased concentration of oxygenated hemoglobin (HbO2) and decreased concentration of deoxygenated hemoglobin (HHb) in the prefrontal cortex as the tasks became...

[hal-01533755] FFTEB: Edge Bundling of Huge Graphs by the Fast Fourier Transform

Publications ENAC - Jeudi, 20 juillet 2017 - 19:29:11
Edge bundling techniques provide a visual simplification of cluttered \ graph drawings or trail sets. While many bundling techniques exist, \ only few recent ones can handle large datasets and also allow selective \ bundling based on edge attributes. We present a new technique \ that improves on both above points, in terms of increasing both the \ scalability and computational speed of bundling, while keeping the \ quality of the results on par with state-of-the-art techniques. For \ this, we shift the bundling process from the image space to the spectral \ (frequency) space, thereby increasing computational speed. We \ address scalability by proposing a data streaming...

[hal-01559020] State of the Art in Edge and Trail Bundling Techniques

Publications ENAC - Mardi, 18 juillet 2017 - 14:27:27
Bundling techniques provide a visual simplification of a graph drawing or trail set, by spatially grouping similar graph edges or trails. This way, the structure of the visualization becomes simpler and thereby easier to comprehend in terms of assessing relations that are encoded by such paths, such as finding groups of strongly interrelated nodes in a graph, finding connections between spatial regions on a map linked by a number of vehicle trails, or discerning the motion structure of a set of objects by analyzing their paths. In this state of the art report, we aim to improve the understanding of graph and trail bundling via the following main contributions. First, we...

[hal-01557327] Taming Mismatches in Inter-Agent Distances for the Formation-Motion Control of Second-Order Agents

Publications ENAC - Vendredi, 7 juillet 2017 - 19:53:22
This paper presents the analysis on the influence of distance mismatches on the standard gradient-based rigid formation control for second-order agents. It is shown that, similar to the first-order case as recently discussed in the literature, these mismatches introduce two undesired group behaviors: a distorted final shape and a steady-state motion of the group formation. We show that such undesired behaviors can be eliminated by combining the standard formation control law with distributed estimators. Finally, we show how the mismatches can be effectively employed as design parameters in order to control a combined translational and rotational motion of the formation.

[hal-01534843] Modeling Operational Variability for Robust Multidisciplinay Design Optimization

Publications ENAC - Mardi, 4 juillet 2017 - 15:48:48
The aim of this paper is to model and propagate operational uncertainties in view of its integration in a multidisciplinary optimization methodology for aircraft robust design. From databases relative to one specic type of long-range airplane, we analyze the variations of four ight parameters (altitude, speed, temperature and range), and build the associated statistical distributions. Then, using an uncertainty propagation methodology, we identify the distribution of operational costs.

[hal-01545617] Design of a robust Controller/Observer for TCP/AQM network: First application to intrusion detection systems for drone fleet

Publications ENAC - Lundi, 3 juillet 2017 - 16:48:36
This paper proposes a robust controller/observer for UAVs network anomaly estimation which is based on both Lyapunov Krasovkii functional and dynamic behavior of TCP (Transmission Control Protocol). Several research works on network anomaly estimation have been led using automatic control techniques and provide methods for designing both observer and command laws dedicated to time delay problem while estimating the anomaly or intrusion in the system. The observer design is based on a linearized fluid-flow model of the TCP behavior and must be associated to an AQM (Active Queue Management) to perform its diagnosis. The developed robust controller/observer in this paper...

[hal-01489204] Unscented Kalman Filtering on Lie Groups

Publications ENAC - Jeudi, 29 juin 2017 - 03:13:37
In this paper, we first consider a simple Bayesian fusion problem in a matrix Lie group, and propose to tackle it using the unscented transform. The method is then leveraged to derive two simple alternative unscented Kalman filters on Lie groups, for both cases of noisy partial measurements of the state, and full state noisy measurements of the state on the group. The general method is applied to a robot localization problem, and results based on experimental data combined with extensive Monte-Carlo simulations at various noise levels illustrate the superiority of the approach over the standard UKF.

[hal-01544676] Dipôle Magnétique Large-Bande pour la Radiogoniométrie 3D à l’aide d’une Antenne Vectorielle

Publications ENAC - Mercredi, 28 juin 2017 - 16:38:38
Un dipôle magnétique large-bande, disposé sur un support métallique plan et réalisé à partir d’un réseau semi-circulaire d’antennes Vivaldi, est présenté dans cette communication. Les caractéristiques radioélectriques obtenues au regard du diagramme de rayonnement, du niveau de polarisation croisée et de bande de fréquences font de ce dipôle un bon candidat pour répondre aux besoins de la radiogoniométrie 3D large-bande à l’aide d’une antenne vectorielle.

[hal-01502815] Controlling a triangular flexible formation of autonomous agents

Publications ENAC - Mercredi, 28 juin 2017 - 16:38:19
In formation control, triangular formations consisting of three autonomous agents serve as a class of benchmarks that can be used to test and compare the performances of different controllers. We present an algorithm that combines the advantages of both position- and distance-based gradient descent control laws. For example, only two pairs of neighboring agents need to be controlled, agents can work in their own local frame of coordinates and the orientation of the formation with respect to a global frame of coordinates is not prescribed. We first present a novel technique based on adding artificial biases to neighboring agents' range sensors such that their eventual...

[halshs-01538698] State Aids granted by regional airports: a two-sided market analysis

Publications ENAC - Mardi, 27 juin 2017 - 03:12:24
A lot of cases had arouse in the past decade about agreements between regional airports and low-cost carriers. These agreements are challenged on the basis of the State Aids European control as they rise concerns not only about competition distortions between airlines but also about fiscal competition risks among Member States or local governments. Such phenomena could be expected as regional airports are characterized by significant overcapacities and overlapping inducing a substitutability for airlines. Surprisingly, the new 2014 guidelines on State Aids granted to airlines open the way to transitory operating aid schemes, an option apparently at odds with the European...
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