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

[hal-02617432] Verification and Validation of Convex Optimization Algorithms for Model Predictive Control

Publications ENAC - Mardi, 26 mai 2020 - 14:46:23
Advanced embedded algorithms are growing in complexity and they are an essential contributor to the growth of autonomy in many areas. However, the promise held by these algorithms cannot be kept without proper attention to the considerably stronger design constraints that arise when the applications of interest, such as aerospace systems, are safety-critical. Formal verification is the process of proving or disproving the "correctness" of an algorithm with respect to a certain mathematical description of it by means of a computer. This article discusses the formal verification of the Ellipsoid method, a convex optimization algorithm, and its code implementation...

[hal-02613891] Cryptanalysis of a rank-based signature with short public keys

Publications ENAC - Lundi, 25 mai 2020 - 17:49:37
Following Schnorr framework for obtaining digital signatures, Song et al. recently proposed a new instantiation of a signature scheme featuring small public keys from coding assumptions in rank metric, which was accepted at PKC'19. Their proposal makes use of rank quasi-cyclic (RQC) codes to reduce the public key size. We show that it is possible to turn a valid, legitimate signature into an efficiently solvable decoding problem, which allows to recover the randomness used for signing and hence the secret key, from a single signature, in about the same amount of time as required for signing

[hal-02603519] New Solutions to Reduce the Time-To-CED and to Improve the CED Robustness of the Galileo I/NAV Message

Publications ENAC - Jeudi, 21 mai 2020 - 03:36:57
In the current framework of Galileo and thanks to the flexibility of the I/NAV message, introducing new pages in order to propose an optimization of the E1-B Galileo signal has been proposed [1]. This optimization process pursues two different objectives. The first objective aims to reduce the Time To First Fix (TTFF), achieved by shortening the time to retrieve the Clock and Ephemerides Data (CED). The second objective aims to improve the resilience and robustness of the CED, particularly under hostile environments. Under the backward compatibility precondition, new outer channel error correction solutions for Galileo I/NAV are proposed in this paper. Especially, a new...

[hal-02570859] Extending Atomic Chain Swaps

Publications ENAC - Mercredi, 20 mai 2020 - 16:38:08
Cryptocurrencies enable users to send and receive value in a trust-less manner. Unfortunately trading the associated assets usually happens on centralized exchange which becomes a trusted third party. This defeats the purpose of a trust-less system. Atomic cross-chain swaps solve this problem for exchanges of value without intermediaries. But they require both blockchains to support Hash locked and Time locked transactions. We propose an extension to atomic swap for blockchains that only support multi-signatures (multisig) transactions. This provides greater capabilities for cross-chain communications without adding any extra trust hypothesis.

[hal-02549387] Pseudorange Measurements with LTE Physical Channels

Publications ENAC - Mardi, 19 mai 2020 - 15:55:34
The long-term evolution (LTE) reference signals, such as the primary synchronization signal (PSS), secondary synchronization signal (SSS) and cell-specific reference signal (CRS), have been studied for navigation.The signal structure including its influence on signal tracking has been previously discussed. However, there are non-reference signals such as the physical broadcast channel (PBCH), physical control format indicator channel (PCFICH), physical hybrid automatic repeat request (HARQ) indicator channel (PHICH) and physical downlink control channel (PDCCH) that can also be used for navigation. To the authors’ knowledge, pseudorange estimates with LTE physical...

[hal-02603868] On sparse graph coding for coherent and noncoherent demodulation

Publications ENAC - Mardi, 19 mai 2020 - 14:32:17
In this paper, we consider a bit-interleaved coded modulation scheme (BICM) composed of an error correcting code serially concatenated with a M-ary non linear modulation with memory. We first compare demodulation strategies for both the coherent and the non coherent cases. Then, we perform an asymptotic analysis and try to show that the design of coding schemes performing well for both the coherent and the non coherent regimes should be done carefully when considering sparse graph based codes such as low-density parity-check (LDPC) codes. It will be shown that optimized coding schemes for the non coherent setting can perform fairly well when using coherent demodulation,...

[hal-02549600] Innovative complexity assessment to support future Capacity Management processes in TBO

Publications ENAC - Vendredi, 15 mai 2020 - 12:26:00
This poster presents research conducted within COTTON project (Grant 783222) funded by the SESAR Joint Undertaking as part of SESAR 2020 Exploratory Research Programme within the framework of the EU’s Horizon 2020 research and innovation programme. COTTON is building an integrated view on future Capacity Management processes by exploring how complexity assessment could help integrating Dynamic Airspace Configuration [1] and Flight Centric ATC solutions [2] taking advantage of trajectory information that is available in a TBO environment and incorporating the uncertainty in the DCB decision-making. Inappropriate sector configuration is a major safety issue as it may...

[hal-02572277] Probabilistic Robustness Estimates for Deep Neural Networks

Publications ENAC - Jeudi, 14 mai 2020 - 11:22:26
Robustness of deep neural networks is a critical issue in practical applications. In the case of deep dense neural networks, under random noise attacks, we propose to study the probability that the output of the network deviates from its nominal value by a given threshold. We derive a simple concentration inequality for the propagation of the input uncertainty through the network using the Cramer-Chernoff method and estimates of the local variation of the neural network mapping computed at the training points. We further discuss and exploit the resulting condition on the network to regularize the loss function during training. Finally, we assess the proposed tail...

[hal-02568473] Fisher-Rao geometry of Dirichlet distributions

Publications ENAC - Mardi, 12 mai 2020 - 13:06:45
In this paper, we study the geometry induced by the Fisher-Rao metric on the parameter space of Dirichlet distributions. We show that this space is geodesically complete and has everywhere negative sectional curvature. An important consequence of this negative curvature for applications is that the Fréchet mean of a set of Dirichlet distributions is uniquely defined in this geometry.

[hal-02559564] Putting the Air Transportation System to sleep: a passenger perspective measured by passenger-generated data

Publications ENAC - Samedi, 9 mai 2020 - 12:14:16
This paper aims at analyzing the effect on the US air transportation system of the travel restriction measures implemented during the COVID-19 pandemic from a passenger perspective. Flight centric data are not already publicly and widely available therefore the traditional metrics used to measure the state of this system are not yet available. Seven metrics based on three different passenger-generated datasets are proposed here. They aim to measure in close to real-time how the travel restriction measures impacted the relation between major stakeholders of the US air transportation system, namely passengers, airports and airlines.
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