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

[hal-01539633] Métriques naturelles sur les fibrés en géométrie de l’information

Publications ENAC - Vendredi, 16 juin 2017 - 13:28:52
La géométrie de l’information permet une formulation élégante de propriétés statistiques. De nombreux travaux ont été dédiés à l’étude des relations entre représentation géométrique et estimation, mais les informations contenues dans l’espace tangent à une variété statistique sont peu exploitées. En géométrie riemannienne, les métriques dites naturelles sur les fibrés tangent donnent une vision de la géométrie de ces objets. Elles sont adaptées à la connexion de Levi-Civita qui n’est pas d’un usage courant en géométrie de l’information. Le travail présenté ici vise à définir un équivalent des métriques naturelles dans le cas de paires de connexions duales, qui ont une...

[hal-01509884] Invariant Unscented Kalman Filter with application to attitude estimation

Publications ENAC - Lundi, 12 juin 2017 - 17:58:44
The Invariant UKF, named IUKF, is a recently introduced algorithm dedicated to nonlinear systems possessing symmetries as illustrated by the quaternion-based kinematics modeling of a mini-UAV (Unmanned Aircraft Vehicle) considered in this paper. Within an invariant framework, this algorithm suggests a systematic approach to determine all the symmetry-preserving terms, without requiring any compatibility condition such as proposed in the PI-IUKF, by introducing both notion of invariant output errors and UKF algorithm formulation. We propose in this paper to evaluate the applicability of our proposed IUKF observer to the case of attitude estimation for small UAVs using low...

[hal-01527006] Probabilistic VOR error due to several scatterers — Application to wind farms

Publications ENAC - Jeudi, 1 juin 2017 - 00:15:25
This paper introduces a method to calculate the VOR error due to multipaths from several known scatterers within known quantiles. In such a configuration, the amplitudes of the multipaths can be numerically or analytically calculated, whereas their phases are modelled as uniformly distributed. A probabilistic formulation of the VOR error that overestimates its variance is introduced to obtain the quantiles. The method is useful to obtain probabilities of occurrence of large VOR errors for multiple configurations and in a short computation time. Examples with wind farms are presented.

[hal-01527004] Comparisons of discrete and continuous propagators for the modelling of low tropospheric propagation

Publications ENAC - Jeudi, 1 juin 2017 - 00:14:44
For modelling the propagation of electromagnetic waves in the low troposphere, the discrete mixed Fourier method is classically used. It is based on a finite-difference approximation of the ground boundary condition. However, the propagator of the split-step Fourier method is derived from continuous equations. In this paper, we apply the finite-difference approximation to the propagation equation. A discrete operator is derived from these discrete equations. The continuous and discrete propagators are compared. The accuracy of these propagators is numerically analysed in free space and over an impedance ground. We show that the discrete propagator avoids some numerical...

[tel-01528481] Modeling and monitoring of new GNSS signal distortions in the context of civil aviation

Publications ENAC - Lundi, 29 mai 2017 - 16:39:07
Global Navigation Satellite Systems (GNSS) is used nowadays in various fields for navigation and positioning including safety-of-life applications. Among these applications is civil aviation that requires a very high quality of service for the most demanding phases of flight. The quality of the GNSS service is typically based on four criteria (integrity, accuracy, availability and continuity), that have to meet International Civil Aviation Organization (ICAO) requirements. To meet these requirements any source of potential service degradations has to be accounted for. One such example is GNSS signal distortions due to the satellite payload which can manifest in two ways...

[hal-01525779] Signal Quality Monitoring Design for Galileo E5a and Galileo E1C signals

Publications ENAC - Lundi, 29 mai 2017 - 16:18:32
Galileo E1C, the pilot component of the E1 Open Service signal (CBOC(6,1,1/11) modulation), Galileo E5a and GPS L5 (BPSK(10) modulation) are signals that will be used by civil aviation receivers for pseudorange computation. To meet stringent requirements defined for civil aviation GNSS receivers, the characterization of distortions which could affect a GNSS signal in a hazardous way is required. In particular, expected signal distortions generated at payload level are described by Threat Models (TMs). Distortions incorporated in the TM are also called Evil WaveForm (EWF). These TMs, and their associated parameter ranges, referred to as Threat Space (TS), are powerful and...

[hal-01526879] Convergence of an estimator of the Wasserstein distance between two continuous probability distributions

Publications ENAC - Jeudi, 25 mai 2017 - 03:09:44
This article is dedicated to the estimation of Wasserstein distances and Wasserstein costs between two distinct continuous distributions $F$ and $G$ on $\mathbb R$. The estimator is based on the order statistics of (possibly dependent) samples of $F$ resp. $G$. We prove the consistency and the asymptotic normality of our estimators.

[hal-01449963] On a three dimensional vision based collision avoidance model

Publications ENAC - Mercredi, 24 mai 2017 - 03:09:14
This paper presents a three dimensional collision avoidance approach for aerial vehicles inspired by coordinated behaviors in biological groups. The proposed strategy aims to enable a group of vehicles to converge to a common destination point avoiding collisions with each other and with moving obstacles in their environment. The interaction rules lead the agents to adapt their velocity vectors through a modification of the relative bearing angle and the relative elevation. Moreover the model satisfies the limited field of view constraints resulting from individual perception sensitivity. From the proposed individual based model, a mean-field kinetic model is derived....

[hal-01521890] Knowledge Discovery in Graphs Through Vertex Separation

Publications ENAC - Vendredi, 19 mai 2017 - 17:38:04
This paper presents our ongoing work on the Vertex Separator Problem (VSP), and its application to knowledge discovery in graphs representing real data. The classic VSP is modeled as an integer linear program. We propose several variants to adapt this model to graphs with various properties. To evaluate the relevance of our approach on real data, we created two graphs of different size from the IMDb database. The model was applied to the separation of these graphs. The results demonstrate how the model is able to semantically separate graphs into clusters.

[hal-01512448] Signal Quality Monitoring for New GNSS Signals

Publications ENAC - Vendredi, 19 mai 2017 - 03:00:53
In the context of GNSS signals and associated augmentation systems modernization, new modulations are envisaged. More precisely Galileo E1C, the pilot component of the E1 Open Service signal (CBOC(6,1,1/11) modulation), Galileo E5a and GPS L5 (BPSK(10) modulation) are signals that will be used by civil aviation airborne receivers for pseudorange computation. To meet stringent requirements defined for civil aviation GNSS receivers, the characterization of distortions which could affect a GNSS signal in a hazardous way is required. In particular, expected signal distortions generated at payload level are described by Threat Models (TM). Distortions incorporate in the TM...
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