Publications

2020

• A lightweight ECC-based authentication scheme for Internet of Things (IoT)
  
  • Hammi Badis
  • Fayad Achraf
  • Khatoun Rida
  • Zeadally Sherali
  IEEE Systems Journal, IEEE, 2020. (10.1109/JSYST.2020.2970167)
  DOI : 10.1109/JSYST.2020.2970167
• Real-Time Deformation with Coupled Cages and Skeletons
  
  • Corda F
  • Thiery J M
  • Livesu M
  • Puppo E
  • Boubekeur T
  • Scateni R
  Computer Graphics Forum, Wiley, 2020. Skeleton-based and cage-based deformation techniques represent the two most popular approaches to control real-time deformations of digital shapes and are, to a vast extent, complementary to one another. Despite their complementary roles, high-end modelling packages do not allow for seamless integration of such control structures, thus inducing a considerable burden on the user to maintain them synchronized. In this paper, we propose a framework that seamlessly combines rigging skeletons and deformation cages, granting artists with a real-time deformation system that operates using any smooth combination of the two approaches. By coupling the deformation spaces of cages and skeletons, we access a much larger space, containing poses that are impossible to obtain by acting solely on a skeleton or a cage. Our method is oblivious to the specific techniques used to perform skinning and cage-based deformation, securing it compatible with pre-existing tools. We demonstrate the usefulness of our hybrid approach on a variety of examples. (10.1111/cgf.13900)
  DOI : 10.1111/cgf.13900
• Minimal linear codes from characteristic functions
  
  • Mesnager Sihem
  • Qi Y.
  • Ru H.
  • Tang C.
  IEEE Transactions on Information Theory, Institute of Electrical and Electronics Engineers, 2020.
• Discrete and stochastic coalitional storage games
  
  • Kiedanski Diego
  • Orda Ariel
  • Kofman Daniel
  , 2020. To achieve a fully decarbonized power grid, a massive deployment of renewable energy resources will be needed, but because of the intermittent nature of their generation, their full potential will not be unleashed unless demand side flexibility plays a bigger role than today. Introducing energy storage at the residential level enables increasing load flexibility, as it allows end-customers to easily change their consumption profile and adapt to the grid requirements. As of today, energy storage for residential consumers represents a considerable investment that is not guaranteed to be profitable. Shared investment models in which a group of consumers jointly acquires energy storage have been proposed in the literature to increase the attractiveness of these devices. Such models naturally employ concepts of cooperative game theory. In this paper, we extend the state-of-the-art cooperative game for modeling the shared investment in storage by adding two crucial extensions: stochasticity of the load and discreetness of the storage device capacity. As our goal is to increase storage capacity in the grid, the number of devices that would be acquired by a group of players that cooperate according to our proposed scheme is compared to the number of devices that would be bought by consumers acting individually. Under the same criteria of customer profitability , simulations using real data reveal that our proposed scheme can increase the deployed storage capacity between 100% and 250%. (10.1145/3396851.3397729)
  DOI : 10.1145/3396851.3397729
• The Compared Costs of Domination, Location-Domination and Identification
  
  • Hudry Olivier
  • Lobstein Antoine
  Discussiones Mathematicae Graph Theory, University of Zielona Góra, 2020, 40 (1), pp.127-147. Let G = (V, E) be a finite graph and r ≥ 1 be an integer. For v ∈ V , let B r (v) = {x ∈ V : d(v, x) ≤ r} be the ball of radius r centered at v. A set C ⊆ V is an r-dominating code if for all v ∈ V , we have B r (v) ∩ C = ∅; it is an r-locating-dominating code if for all v ∈ V , we have B r (v) ∩ C = ∅, and for any two distinct non-codewords x ∈ V \ C, y ∈ V \ C, we have B r (x) ∩ C = B r (y) ∩ C; it is an r-identifying code if for all v ∈ V , we have B r (v) ∩ C = ∅, and for any two distinct vertices x ∈ V , y ∈ V , we have B r (x) ∩ C = B r (y) ∩ C. We denote by γ r (G) (respectively, ld r (G) and id r (G)) the smallest possible cardinality of an r-dominating code (respectively, an r-locating-dominating code and an r-identifying code). We study how small and how large the three differences id r (G)−ld r (G), id r (G)−γ r (G) and ld r (G) − γ r (G) can be. (10.7151/dmgt.2129)
  DOI : 10.7151/dmgt.2129
• La transmission « naturelle » des savoirs
  
  • Dessalles Jean-Louis
  , 2020, pp.49-58. Les sociétés de chasseurs-cueilleurs n'ont pas d'écoles. Elles accumulent pourtant des savoirs, elles possèdent des langues et des cultures sophistiquées. Si l'on compare notre espèce aux autres primates, tout est différent. Les cultures animales existent, mais elles sont si restreintes qu'elles sont longtemps passées inaperçues aux yeux des éthologues. Pourquoi existe-t-il tant de « savoirs » dans notre espèce ? Et pourquoi les transmettons-nous ? Si la question semble saugrenue, c'est parce que nous avons perdu de vue le caractère apparemment contre-nature de ce comportement. Un comportement contre-nature Les chimpanzés étudiés par l'éthologue Tetsuro Matsuzawa [1994] dans la forêt de Bossou, en Guinée, cassent spontanément des noix très dures en posant la noix sur une pierre (l'enclume) et en frappant avec une autre pierre (le marteau). Leur expertise demande des années d'imitation des congénères. Les jeunes l'acquièrent en explorant un peu au hasard des centaines de combinaisons de paramètres : choix des pierres, position de l'enclume, face et angle de frappe, etc. Les adultes sont très bienveillants vis-à-vis des jeunes qui les observent, mais on ne les voit jamais leur montrer activement le bon geste et encore moins intervenir lorsqu'ils font des erreurs à répétition. L'espèce humaine offre un contraste saisissant. Prenons l'exemple des forums techniques. Imaginons un étudiant qui apprend le langage informatique Python et cherche à savoir comment inverser une liste. Il tape « python reverse list » sur son moteur de recherche et arrive sur un forum comme Stackoverflow. Il constate que sa question a déjà été posée par un autre débutant et qu'elle a obtenu 29 réponses qui ont elles-mêmes reçu 34 commentaires. Les personnes qui ont pris la peine de répondre ne connaissent pas l'étudiant. Elles font partie d'une communauté, celle des programmeurs Python, au sein de laquelle l'entraide spontanée est considérée comme normale. Paru dans : P. Pion & N. Schlanger (Eds.), Apprendre-Archéologie de la transmission des savoirs, pp. 49-58. Paris: La Découverte, 2020.
• Improving Interpretability for Computer-aided Diagnosis tools on Whole Slide Imaging with Multiple Instance Learning and Gradient-based Explanations
  
  • Pirovano A.
  • Heuberger H.
  • Berlemont S.
  • Ladjal S.
  • Bloch Isabelle
  , 2020, LNCS 12446, pp.43-53.
• From Interferometric to Tomographic Synthetic Aperture Radar. Scatterer unmixing in urban areas: A review of synthetic aperture radar tomography-processing techniques
  
  • Rambour Clement
  • Budillon Alessandra
  • Johnsy Angel
  • Denis Loïc
  • Tupin Florence
  • Schirinzi Gilda
  IEEE geoscience and remote sensing magazine, IEEE, 2020, 8 (2).
• Complexity of voting procedures
  
  • Hudry Olivier
  , 2020.
• phiflow: A Differentiable PDE Solving Framework for Deep Learning via Physical Simulations
  
  • Holl Philipp
  • Koltun Vladlen
  • Um Kiwon
  • Thuerey Nils
  , 2020.
• « Je dois y aller ». Analyses de séquences de clôtures entre humains et robot
  
  • Licoppe Christian
  • Rollet Nicolas
  Réseaux : communication, technologie, société, Lavoisier, La Découverte, 2020, N°220-221 (2), pp.151. (10.3917/res.220.0151)
  DOI : 10.3917/res.220.0151
• Donsker's theorem in {Wasserstein}-1 distance
  
  • Coutin Laure
  • Decreusefond Laurent
  Electronic Communications in Probability, Institute of Mathematical Statistics (IMS), 2020, 25, pp.1--13. We compute the Wassertein-1 (or Kantorovitch-Rubinstein) distance between a random walk in $R^d$ and the Brownian motion. The proof is based on a new estimate of the Lipschitz modulus of the solution of the Stein's equation. As an application, we can evaluate the rate of convergence towards the local time at 0 of the Brownian motion. (10.1214/20-ECP308)
  DOI : 10.1214/20-ECP308
• Tunable All-Optical Modulation and Building Blocks for Optical Neurons at Mid-Infrared Wavelength
  
  • Spitz O
  • Wu J
  • Herdt A
  • Carras M
  • Maisons G
  • Elsässer W
  • Wong C.-W
  • Grillot F
  , 2020. Quantum cascade lasers (QCLs) under optical feedback can output several non-linear dynamics whose properties depend on the reinjected light polarization. We demonstrate all-optical modulation, thresholding and excitability in QCLs, to experimentally build basic optical neurons.
• Conveying Emotions Through Device-Initiated Touch
  
  • Teyssier Marc
  • Bailly Gilles
  • Pelachaud Catherine I
  • Lecolinet Eric
  IEEE Transactions on Affective Computing, Institute of Electrical and Electronics Engineers, 2020, pp.1-1. Humans have the ability to convey an array of emotions through complex and rich touch gestures. However, it is not clear how these touch gestures can be reproduced through interactive systems and devices in a remote mediated communication context. In this paper, we explore the design space of device-initiated touch for conveying emotions with an interactive system reproducing a collection of human touch characteristics. For this purpose, we control a robotic arm to touch the forearm of participants with different force, velocity and amplitude characteristics to simulate human touch. In view of adding touch as an emotional modality in human-machine interaction, we have conducted two studies. After designing the touch device, we explore touch in a context-free setup and then in a controlled context defined by textual scenarios and emotional facial expressions of a virtual agent. Our results suggest that certain combinations of touch characteristics are associated with the perception of different degrees of valence and of arousal. Moreover, in the case of non-congruent mixed signals (touch, facial expression, textual scenario) not conveying a priori the same emotion, the message conveyed by touch seems to prevail over the ones displayed by the visual and textual signals. (10.1109/TAFFC.2020.3008693)
  DOI : 10.1109/TAFFC.2020.3008693
• Power efficient all-fiberized 12-core erbium/ytterbium doped optical amplifier
  
  • Mélin Gilles
  • Kerampran Romain
  • Monteville Achille
  • Bordais Sylvain
  • Robin Thierry
  • Landais David
  • Lebreton Aurélien
  • Jaouën Yves
  • Taunay Thierry
  , 2020, pp.M4C.2. (10.1364/OFC.2020.M4C.2)
  DOI : 10.1364/OFC.2020.M4C.2
• Raman-free fibered photon-pair source
  
  • Cordier Martin
  • Delaye Philippe
  • Gérôme Frédéric
  • Benabid Fetah
  • Zaquine Isabelle
  Scientific Reports, Nature Publishing Group, 2020, 10, pp.1650. Raman-scattering noise in silica has been the key obstacle toward the realisation of high quality fiber-based photon-pair sources. Here, we experimentally demonstrate how to get past this limitation by dispersion tailoring a xenon-filled hollow-core photonic crystal fiber. The source operates at room temperature, and is designed to generate Raman-free photon-pairs at useful wavelength ranges, with idler in the telecom, and signal in the visible range. We achieve a coincidence-to-accidentals ratio as high as 2740 combined with an ultra low heralded second order coherence g(2)H(0)=0.002, indicating a very high signal to noise ratio and a negligible multi-photon emission probability. Moreover, by gas-pressure tuning, we demonstrate the control of photon frequencies over a range as large as 13 THz, covering S-C and L telecom band for the idler photon. This work demonstrates that hollow-core photonic crystal fiber is an excellent platform to design high quality photon-pair sources, and could play a driving role in the emerging quantum technology. (10.1038/s41598-020-58229-7)
  DOI : 10.1038/s41598-020-58229-7
• Spiking Neural Networks and online learning: An overview and perspectives
  
  • Lobo Jesus
  • del Ser Javier
  • Bifet Albert
  • Kasabov Nikola
  Neural Networks, Elsevier, 2020, 121, pp.88-100. Applications that generate huge amounts of data in the form of fast streams are becoming increasingly prevalent, being therefore necessary to learn in an online manner. These conditions usually impose memory and processing time restrictions, and they often turn into evolving environments where a change may affect the input data distribution. Such a change causes that predictive models trained over these stream data become obsolete and do not adapt suitably to new distributions. Specially in these non-stationary scenarios, there is a pressing need for new algorithms that adapt to these changes as fast as possible, while maintaining good performance scores. Unfortunately, most off-the-shelf classification models need to be retrained if they are used in changing environments, and fail to scale properly. Spiking Neural Networks have revealed themselves as one of the most successful approaches to model the behavior and learning potential of the brain, and exploit them to undertake practical online learning tasks. Besides, some specific flavors of Spiking Neural Networks can overcome the necessity of retraining after a drift occurs. This work intends to merge both fields by serving as a comprehensive overview, motivating further developments that embrace Spiking Neural Networks for online learning scenarios, and being a friendly entry point for non-experts. (10.1016/j.neunet.2019.09.004)
  DOI : 10.1016/j.neunet.2019.09.004
• On the decoding of Barnes-Wall lattices
  
  • Corlay Vincent
  • Boutros Joseph
  • Ciblat Philippe
  • Brunel Loïc
  , 2020. We present new efficient recursive decoders for the Barnes-Wall lattices based on their squaring construction. The analysis of the new decoders reveals a quasi-quadratic complexity in the lattice dimension. The error rate is shown to be close to the universal lower bound in dimensions 64 and 128.
• Introduction of 3D Modeling and Peripheral Nerve Tractography in the Management of Pelvic Tumors
  
  • Goulin Jeanne
  • Meignan Pierre
  • Blanc Thomas
  • Delmonte Alessandro
  • Peyrot Quoc
  • Berteloot Laureline
  • Boddaert Nathalie
  • Bloch Isabelle
  • Sarnacki Sabine
  , 2020.
• Weighted Empirical Risk Minimization: Transfer Learning based on Importance Sampling
  
  • Clémençon Stéphan
  • Vogel Robin
  • Achab Mastane
  • Tillier Charles
  , 2020. We consider statistical learning problems, when the distribution P of the training observations Z 1 ,. .. , Z n differs from the distribution P involved in the risk one seeks to minimize (referred to as the test distribution) but is still defined on the same measurable space as P and dominates it. In the unrealistic case where the likelihood ratio Φ(z) = dP/dP (z) is known, one may straightforwardly extends the Empirical Risk Minimization (ERM) approach to this specific transfer learning setup using the same idea as that behind Importance Sampling, by minimizing a weighted version of the empirical risk functional computed from the 'biased' training data Z i with weights Φ(Z i). Although the importance function Φ(z) is generally unknown in practice, we show that, in various situations frequently encountered in practice, it takes a simple form and can be directly estimated from the Z i 's and some auxiliary information on the statistical population P. By means of linearization techniques, we then prove that the generalization capacity of the approach aforementioned is preserved when plugging the resulting estimates of the Φ(Z i)'s into the weighted empirical risk. Beyond these theoretical guarantees, numerical results provide strong empirical evidence of the relevance of the approach promoted in this article.
• Pythagore, J'adore
  
  • Zayana Karim
  Repères IREM, IREM, 2020. Ce texte reprend la trame d'un atelier proposé en avril-mai 2019 à Besançon pour le cinquantenaire des IREM, à Paris dans le cadre d'un plan national de formation, ainsi que dans les INSPÉ de Grenoble, Lyon et Nantes auprès des professeurs stagiaires (mathématiques et math-sciences). Il propose une étude, circonscrite aux programmes du second degré et à l'aune d'un questionnement QQOQCP 1 , de l'oeuvre de Pythagore. Flânons ainsi entre histoire, géographie, physique, musique, philosophie et bien sûr mathématiques... par Karim Zayana Inspecteur général, professeur invité à l'institut Mines-Télécom Avec esprit, humour et un zeste d'impertinence, on l'a mis en rap [1] et on l'a mis par terre [2] tandis qu'il nous mettait en pleurs [3]. En chanson, les artistes Isaaba, Renaud ou Aldebert, font rimer Pythagore sur nos chagrins d'école. Le grand homme ne sonne pourtant pas qu'avec « hardcore » et « mort »… À notre tour, dansons sur son trésor qui, charrié par les siècles, voyagea jusqu'à nous. L'exercice est plus sérieux qu'il y paraît, la simplicité d'un théorème, fût-il enfantin, n'est souvent qu'illusion. En savourer les mille et un reflets, en saisir l'essence, embrasser sa richesse reste un chemin ardu. La compréhension naît de l'effort, puis le plaisir de la compréhension. Là est la délivrance, point d'orgue culminant d'un processus long et sinueux qu'Heidegger résume en deux mots, chercher et questionner : « Tout questionner est un chercher. Tout chercher tire de ce qu'il recherche la direction qui précède et guide sa démarche. Questionner, c'est, sur le plan de la connaissance, chercher l'élément quant au fait qu'il soit et quant à son être tel. Chercher, sur le plan de la connaissance, s'appelle " recherche " quand est dégagé pour le déterminer ce après quoi la question se pose. » [4]. Toute la difficulté de trouver un sens aux choses est ici rendue par cette phrase, aussi complexe qu'abstraite. Il en va de même pour qui veut apprécier les mathématiques. Heureusement nous disposons d'outils. L'angle pédagogique des compétences en est un, et nous pourrions interroger en quoi la science des pythagoriciens les valide ou les développe, de calculer à communiquer en passant par modéliser sans oublier les facultés raisonner, représenter, chercher qu'il est d'usage d'effeuiller telles les pétales d'une fleur [5]. Une autre approche, que nous privilégions ici, relève de la méthodologie scientifique. Quand un chercheur analyse un problème, il le soumet un jour ou l'autre à ce crible [6] : 1. C'est de Qui, c'est Quand, c'est Où ? 1 Qui, Quand, Où, Quoi, Comment, Combien, Pour quoi/qui. Méthode empirique de questionnement circonstancié très utilisée en journalisme (de façon consciente), mais aussi en R&D (de façon sans doute moins formalisée).
• D’un simple dessin de Léonard de Vinci aux "formes premières
  
  • Crettez Jean-Pierre
  ISTE Openscience, ISTE Ltd, 2020, 4 (4). (10.21494/ISTE.OP.2020.0557)
  DOI : 10.21494/ISTE.OP.2020.0557
• Change Detection Based on the Coefficient of Variation in SAR Time-Series of Urban Areas
  
  • Colin Koeniguer Elise
  • Nicolas Jean-Marie
  Remote Sensing, MDPI, 2020, 12 (13), pp.2089. This paper discusses change detection in SAR time-series. First, several statistical properties of the coefficient of variation highlight its pertinence for change detection. Subsequently, several criteria are proposed. The coefficient of variation is suggested to detect any kind of change. Furthermore, several criteria that are based on ratios of coefficients of variations are proposed to detect long events, such as construction test sites, or point-event, such as vehicles. These detection methods are first evaluated on theoretical statistical simulations to determine the scenarios where they can deliver the best results. The simulations demonstrate the greater sensitivity of the coefficient of variation to speckle mixtures, as in the case of agricultural plots. Conversely, they also demonstrate the greater specificity of the other criteria for the cases addressed: very short event or longer-term changes. Subsequently, detection performance is assessed on real data for different types of scenes and sensors (Sentinel-1, UAVSAR). In particular, a quantitative evaluation is performed with a comparison of our solutions with baseline methods. The proposed criteria achieve the best performance, with reduced computational complexity. On Sentinel-1 images containing mainly construction test sites, our best criterion reaches a probability of change detection of 90% for a false alarm rate that is equal to 5%. On UAVSAR images containing boats, the criteria proposed for short events achieve a probability of detection equal to 90% of all pixels belonging to the boats, for a false alarm rate that is equal to 2%. (10.3390/rs12132089)
  DOI : 10.3390/rs12132089
• Time Series Source Separation with Slow Flows
  
  • Pineau Edouard
  • Razakarivony Sébastien
  • Bonald Thomas
  , 2020. In this paper, we show that slow feature analysis (SFA), a common time series decomposition method, naturally fits into the flow-based models (FBM) framework, a type of invertible neural latent variable models. Building upon recent advances on blind source separation, we show that such a fit makes the time series decomposition identifiable.
• Real Time Multiscale Rendering of Dense Dynamic Stackings
  
  • Michel Elie
  • Boubekeur Tamy
  Computer Graphics Forum, Wiley, 2020, 39 (7), pp.169-179. Dense dynamic aggregates of similar elements are frequent in natural phenomena and challenging to render under full real time constraints. The optimal representation to render them changes drastically depending on the distance at which they are observed, ranging from sets of detailed textured meshes for near views to point clouds for distant ones. Our multiscale representation use impostors to achieve the mid-range transition from mesh-based to point-based scales. To ensure a visual continuum, the impostor model should match as closely as possible the mesh on one side, and reduce to a single pixel response that equals point rendering on the other. In this paper, we propose a model based on rich spherical impostors, able to combine precomputed as well as dynamic procedural data, and offering seamless transitions from close instanced meshes to distant points. Our approach is architectured around an on-the-fly discrimination mechanism and intensively exploits the rough spherical geometry of the impostor proxy. In particular, we propose a new sampling mechanism to reconstruct novel views from the precomputed ones, together with a new conservative occlusion culling method, coupled with a two-pass rendering pipeline leveraging early-Z rejection. As a result, our system scales well and is even able to render sand, while supporting completely dynamic stackings. (10.1111/cgf.14135)
  DOI : 10.1111/cgf.14135