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Toutes les publications de recherche de l'ENAC en temps réel.

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

Publications ENAC - Samedi, 3 août 2019 - 03:43:12
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-02194727] Les fonctions d'onde externe et interne : une double solution à la Louis de Broglie ?

Publications ENAC - Samedi, 27 juillet 2019 - 03:18:11
Nous proposons une grille de lecture de la mécanique quantique correspondant aux spécifications de la théorie de la double solution de Louis de Broglie. Le principe est de décomposer l'évolution d'un système quantique sous la forme de deux fonctions d'onde : une fonction d'onde externe correspondant à l'évolution de son centre de masse et une fonction d'onde interne correspondant à l'évolution de ses variables internes dans le référentiel du centre de masse. La décomposition mathématique n'est possible que dans certains cas car de nombreuses interactions relient ces deux parties. En outre, ces deux fonctions d'onde vont avoir des sens et des interprétations différentes....

[hal-02191101] A New Cycle-Slip Detection Algorithm for Network RTK Using Optimal Dual-Frequency Carrier-Phase Combinations

Publications ENAC - Mercredi, 24 juillet 2019 - 16:28:23
Many strategies for treating dual-frequency cycle slip have been studied over the years; however, the conventional method using the Melbourne-Wübbena (MW) combination is vulnerable to pseudorange multipath effects. In this paper, we propose a new detection algorithm of dual-frequency cycle slip using only carrier-phase stationary observations for the network real-time kinematic (RTK) system which generates high-precision corrections for user. Two independent and complementary carrierphase combinations, called the ionospheric negative (IN) and ionospheric positive (IP) combinations in this paper, are employed for avoiding insensitive pairs. They can successfully detect...

[hal-02192467] Performance Improvement of Time-Differenced Carrier Phase Measurement-Based Integrated GPS/INS Considering Noise Correlation

Publications ENAC - Mercredi, 24 juillet 2019 - 11:30:17
In this study, we combined a time-differenced carrier phase (TDCP)-based global positioning system (GPS) with an inertial navigation system (INS) to form an integrated system that appropriately considers noise correlation. The TDCP-based navigation system can determine positions precisely based on high-quality carrier phase measurements without difficulty resolving integer ambiguity. Because the TDCP system contains current and previous information that violate the format of the conventional Kalman filter, a delayed state filter that considers the correlation between process and measurement noise is utilized to improve the accuracy and reliability of the TDCP-based GPS/...

[hal-02192449] A New Method to Improve Detection of Co-seismic Ionospheric Disturbances Using Sequential Measurement Combination

Publications ENAC - Mercredi, 24 juillet 2019 - 10:00:57
Earthquakes generate energy that propagates into the ionosphere and incurs co-seismic ionospheric disturbances (CIDs), which can be observed in ionospheric delay measurements. In most cases, the CID has a weak signal strength because the energy in the atmosphere transferred from the earthquake dissipates as it travels toward the ionosphere. It is particularly hard to observe at reference stations that are located far from the epicenter. As the number of Global Navigation Satellite System stations and their positions are restricted, it is important to employ weak CID data in the analysis by improving the detection performance of CIDs. In this study, we suggest a new...

[hal-02191751] Making Trustable Satellite Experiments: an Application to a VoIP Scenario

Publications ENAC - Mercredi, 24 juillet 2019 - 03:21:48
How many times have ever asked yourself: "Can I trust my satellite experiments' outcome?". Performing experiments on real satellite system can either be (1)~costly, as the radio resource may be scarce or (2)~not possible, as you can hardly change the waveforms transmitted by the satellite platform. Moreover, assessing user applications QoE can hardly be done using only simulated environments while the QoS modeling of a satellite system can often lead to non-conclusive or ambiguous results. The aim of this paper is to bring out representative solutions allowing the networking community to drive consistent experiments using open-source tools. To this end, we...

[hal-02191770] Doubly-Selective Channel Estimation for Continuous Phase Modulation

Publications ENAC - Mercredi, 24 juillet 2019 - 03:21:48
In this paper, we present two Data-Aided channel estimators for Continuous Phase Modulation (CPM) in the case of transmissions over doubly -selective channels. They both capitalize on the Basis Expansion Model (BEM), widely used for OFDM systems and for Single Carrier transmission with linear modulation. However, in the case of CPM signals, we need to work on a over-sampled received signal (fractionally-spaced representation) as the equalization techniques are also working on the over-sampled received signal. The first one is a classical Least Squares (LS) estimation of the BEM parameters whereas the second channel estimator introduces first a parametric dependence on...

[hal-02191840] A New Exact Low-Complexity MMSE Equalizer for Continuous Phase Modulation

Publications ENAC - Mercredi, 24 juillet 2019 - 03:21:48
This letter introduces a new low-complexity frequency-domain equalizer for continuous phase modulations (CPM). The derivation of a fractionally spaced representation for circular block-based CPM leads, without any approximation, to a simple yet efficient frequency-domain equalization. The proposed equalizer is compared to the state-of-the-art approaches. Simulation results show the equivalence in terms of performance with a lower or similar complexity.

[hal-01166854] Model Driven Approach to design a Secure Routing Protocol for UAV Ad Hoc Networks

Publications ENAC - Mardi, 23 juillet 2019 - 16:34:24
UAANET (UAV Ad Hoc Network) is a wireless network that is able to organize itself without a pre-existing infrastructure. It consists of forming an ad hoc network with multiple UAVs and the Ground Control Station (GCS). In order to route data packets between nodes, a routing protocol is required. This routing protocol must not only satisfy the UAANET network requirements but also the validation requirements with a formal method to verify the routing protocol conformance. This will eventually contribute to the certification of the UAANET communication network (e.g to be compatible with the specification document DO 178C). In this paper, we propose a validation model of a...
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