Archives Ouvertes HAL

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

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

Publications ENAC - Jeudi, 21 mars 2019 - 02:25:02
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-02068834] EDURA: an Evolvable Demonstrator for Upset Recovery Approaches with a 3D-printed Launcher

Publications ENAC - Mercredi, 20 mars 2019 - 02:19:29
As in-flight loss of control has remained a severe threat to aviation, aeronautical research designed several approaches for upset recovery, few of which has been demonstrated in flight tests. The ongoing success of micro air vehicles, however , rises the possibility of cheap and flexible flight demonstrations. In this paper, we present the concept of and first steps towards an aerial experimental platform for upset recovery: EDURA. EDURA is part of the CONVEX project to investigate , develop, and demonstrate non-linear upset recovery control laws in a fixed-wing MAV.

[hal-02068882] Performance of unmanned aircrafts in the event of loss-of-control

Publications ENAC - Mercredi, 20 mars 2019 - 02:19:29
Loss of control is a severe and immediate consequence of faults in an unmanned aircraft system during flight. Without recovery, detection of admissible landing spots is necessary to avoid causalities. This case study considers exemplary the MAKO unmanned aircraft and discusses viable trim conditions for a drone system after faults of propulsion and elevator using continuation analysis. Furthermore, simple estimates of reachable zones for controlled flight into terrain are provided.

[hal-02056992] A Design Workbench for Interactive Music Systems

Publications ENAC - Mardi, 19 mars 2019 - 16:57:14
This chapter discusses possible links between the fields of computer music and human-computer interaction (HCI), particularly in the context of the MIDWAY project between Inria, France and McGill University, Canada. The goal of MIDWAY is to construct a “musical interaction design workbench” to facilitate the exploration and development of new interactive technologies for musical creation and performance by bringing together useful models, tools, and recent developments from computer music and HCI. Such models and tools can expand the means available for musical expression, as well as provide HCI researchers with a better foundation for the design of tools for a class of...

[hal-02059899] Physical layer abstraction for performance evaluation of leo satellite systems for iot using time-frequency aloha scheme

Publications ENAC - Samedi, 16 mars 2019 - 03:06:36
One of the main issues in using a Low Earth Orbit (LEO) satellite constellation to extend a Low-Powered Wide Area Network is the frequency synchronization. Using a link based on random access solves this concern, but also prevents delivery guarantees, and implies less predictable performance. This paper concerns the estimation of Bit Error Rate (BER) and Packet Error Rate (PER) using physical layer abstractions under a time and frequency random scheme, namely Time and Frequency Aloha. We first derive a BER calculation for noncoded QPSK transmission with one collision. Then, we use the 3GPP LTE NB-IoT coding scheme. We analyze the interference that could be induced by...

[hal-02059933] 3GPP NB-IoT coverage extension using LEO satellites

Publications ENAC - Samedi, 16 mars 2019 - 03:06:37
Machine-Type Communications are meeting a growing interest on the consumer market. Dedicated technologies arise to support more robust communications involving a massive number of low cost, low energy-consuming devices This paper discusses the coverage extension of a Low-Powered Wide Area Network using a Low Earth Orbit satellite constellation, benefiting from the improved performance of a recent standard. The transmission complies with the user equipment specifications standardized as NB-IoT by 3GPP in Release 13. This radio technology is an update on LTE standard with enhanced performances: the supported path loss can be 20 dB higher than with legacy LTE. This...

[tel-02064303] Wideband Reconfigurable Vector Antenna for 3-D Direction Finding Application

Publications ENAC - Samedi, 16 mars 2019 - 02:56:06
Direction finding plays a crucial role in various civilian and military applications, related to either radionavigation or radiolocation. Most of the direction finding antennas operate over a wide frequency band, but only a minority of them enable the direction of arrival estimation of an incoming electromagnetic field over a 3-D angular coverage (i.e., estimation of both azimuth and elevation angles). An original approach to obtain a 3-D angular coverage consists in measuring the six components of the incident electromagnetic field through a so-called vector antenna. The aim of this Ph.D. is to design a passive, compact and wideband vector antenna in order to cover a...

[tel-02063761] Optimisation topologique de structures sous contraintes de flambage

Publications ENAC - Vendredi, 15 mars 2019 - 02:28:15
L’optimisation topologique vise à concevoir une structure en recherchant la disposition optimale du matériau dans un espace de conception donné, permettant ainsi de proposer des designs optimaux innovants. Cette thèse est centrée sur l’optimisation topologique pour des problèmes de conception de structures prenant en compte des contraintes de flambage. Dans une large variété de domaines de l’ingénierie, la conception innovante de structures est cruciale. L’allègement des structures lors la phase de conception tient une place prépondérante afin de réduire les coûts de fabrication. Ainsi l’objectif est souvent la minimisation de la masse de la structure à concevoir. En ce...

[hal-02053694] Integrated optimization of terminal maneuvering area and airport at the macroscopic level

Publications ENAC - Mardi, 12 mars 2019 - 11:00:10
Airports and surrounding airspaces are limited in terms of capacity and represent the major bottlenecks of the air traffic management system. This paper addresses the problems of terminal airspace management and airport congestion management at the macroscopic level through the integrated control of arrivals and departures. Conflict detection and resolution methods are applied to a predefined terminal route structure. Different airside components are modeled using network abstraction. Speed, arrival and departure times, and runway assignment are managed by using an optimization method. An adapted simulated annealing heuristic combined with a time decomposition approach...
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