Archives Ouvertes HAL
Toutes les publications de l'ENAC en direct.
All ENAC publications.
[hal-04550976] Extending Guiding Vector Field to track unbounded UAV paths
A recent advance in vector field path following is the introduction of the Parametric Guiding Vector Field method. It allows for singularity-free vector fields with strong convergence guarantees, usable even for self-intersecting paths. However, the method requires significant gain tuning for practical use. In particular, for unbounded paths, the gains will inevitably become ill-suited for efficient path following. We propose a method to overcome this issue by introducing a dynamic step adaptation strategy, which provides additional normalization properties to the field. This allows the following of unbounded curves and reduces the number of gains to tune. The proposed...
[hal-04543171] Adversarial Robustness with Partial Isometry
Despite their remarkable performance, deep learning models still lack robustness guarantees, particularly in the presence of adversarial examples. This significant vulnerability raises concerns about their trustworthiness and hinders their deployment in critical domains that require certified levels of robustness. In this paper, we introduce an information geometric framework to establish precise robustness criteria for l2 white-box attacks in a multi-class classification setting. We endow the output space with the Fisher information metric and derive criteria on the input–output Jacobian to ensure robustness. We show that model robustness can be achieved by constraining...
[hal-04543170] VTOL site location considering obstacle clearance during approach and departure
Urban air mobility (UAM) extends urban transportation to low-altitude airspace using electric vertical take-off and landing (eVTOL) vehicle to reduce traffic congestion. The vertical take-off and landing (VTOL) site connecting ground and air transport is the critical infrastructure of the UAM. Determining its locations is essential for the design and operation of the air route. This study focuses on the problem of the location of the VTOL site, using Shenzhen as the study area, and establishes an integer programming model with the objective of maximizing travel cost savings to identify the optimal locations of the VTOL sites. This study is different from existing ones in...
[hal-04543167] Status quo and challenges in air transport management research
Air transport management research, concerned with all facets of aviation operations, policies, and strategies, is an essential element of making our aviation system more sustainable and preparing it for the challenges inherentto the present and future. Based on a data-driven categorization of almost 2,000 papers published on the subject, we discuss the status quo in air transport management research. Through our data-driven categorization we have identified 15 broad topics. For each topic, we provide a description of the state of the art and propose 2-3 challenges, respectively. Overall, our study provides a set of 35 challenges to the research community. Accordingly, we...
[hal-04541060] On the asymptotic performance of time-delay and Doppler estimation with a carrier modulated by a band-limited signal
Time-delay and Doppler estimation is crucial in various engineering fields, as estimating these parameters constitutes one of the key initial steps in the receiver’s operational sequence. Due to its importance, several expressions of the Cramér–Rao Bound (CRB) and Maximum Likelihood Estimation (MLE) have been derived over the years. Previous contributions started from the assumption that the transmission process introduces an unknown phase, which hindered the explicit consideration of the time-delay parameter in the carrier-phase component in theoretical derivations. However, this contribution takes into account this additional term under the assumption that such an...
[hal-04528859] Assessing GNSS Carrier-to-Noise-Density Ratio Estimation in The Presence of Meaconer Interference
In the context of Global Navigation Satellite Systems (GNSS), the measure of the Carrier-to-Noise Density Ratio (C/N0) plays a critical role in evaluating received signal quality, particularly in the presence of Radio-Frequency Interferences such as from a meaconer. This paper presents a dual-step strategy to characterize C/N0 under meaconer influence. First, the theoretical expression of the real C/N0 is computed. Second, a model to predict meaconer-induced distortion on the Moment Method (MM) and the Narrowband-Wideband Power Ratio (NWPR) estimators is derived. The comparison between real and estimated C/N0 reveals a deviation between NWPR, MM and real C/N0. In essence...
[hal-04521789] Propagation électromagnétique en atmosphère turbulente inhomogène réaliste
La stochastic multiple phase screen method (sMPS) est largement utilisée pour modéliser l’impact de la turbulence troposphérique sur la propagation d’ondes électromagnétiques. Elle repose généralement sur l’utili- sation de spectres de Kolmogorov homogènes. Cette étude présente deux méthodes pour générer une turbulence in- homogène avec la sMPS. L’approche LES-Kolmogorov utilise des profils verticaux de la constante de structure turbulente directement extraits de simulation atmosphé- riques, tandis que la méthode Bump-Kolmogorov (BK- model) les reproduit approximativement avec un modèle paramétrique. Les calculs de profils de log-amplitude mettent en évidence l’impact...