Publications

2018

• 4 Leaf Clover RenderingImproving Monte Carlo Path Tracing with Double hierarchies and collaborative denoising
  
  • Boubekeur Tamy
  , 2018.
• The challenge of cerebral magnetic resonance imaging in neonates: A new method using mathematical morphology for the segmentation of structures including diffuse excessive high signal intensities
  
  • Xu Yongchao
  • Morel Baptiste
  • Dahdouh Sonia
  • Puybareau Élodie
  • Virzì Alessio
  • Urien Hélène
  • Géraud Thierry
  • Adamsbaum Catherine
  • Bloch Isabelle
  Medical Image Analysis, Elsevier, 2018, 48, pp.75-94. Preterm birth is a multifactorial condition associated with increased morbidity and mortality. Diffuse excessive high signal intensity (DEHSI) has been recently described on T2-weighted MR sequences in this population and thought to be associated with neuropathologies. To date, no robust and reproducible method to assess the presence of white matter hyperintensities has been developed, perhaps explaining the current controversy over their prognostic value. The aim of this paper is to propose a new semi-automated framework to detect DEHSI on neonatal brain MR images having a particular pattern due to the physiological lack of complete myelination of the white matter. A novel method for semi-automatic segmentation of neonatal brain structures and DEHSI, based on mathematical morphology and on max-tree representations of the images is thus described. It is a mandatory first step to identify and clinically assess homogeneous cohorts of neonates for DEHSI and/or volume of any other segmented structures. Implemented in a user-friendly interface, the method makes it straightforward to select relevant markers of structures to be segmented, and if needed, apply eventually manual corrections. This method responds to the increasing need for providing medical experts with semi-automatic tools for image analysis, and overcomes the limitations of visual analysis alone, prone to subjectivity and variability. Experimental results demonstrate that the method is accurate, with excellent reproducibility and with very few manual corrections needed. Although the method was intended initially for images acquired at 1.5T, which corresponds to usual clinical practice, preliminary results on images acquired at 3T suggest that the proposed approach can be generalized. (10.1016/j.media.2018.05.003)
  DOI : 10.1016/j.media.2018.05.003
• Attribute‐based broadcast encryption scheme for lightweight devices
  
  • Canard Sébastien
  • Hieu Phan Duong
  • Trinh Viet Cuong
  IET Information Security, Institution of Engineering and Technology, 2018, 12 (1), pp.52-59. (10.1049/iet-ifs.2017.0157)
  DOI : 10.1049/iet-ifs.2017.0157
• Shannon et la théorie de l'information
  
  • Rioul Olivier
  , 2018. Analyse de la publication de C.E. Shannon, &quot;A mathematical Theory of Communication&quot;, The Bell System Technical Journal, Vol. 27, pp. 379–423, 623-656, July, October, 1948 (55 pages)</p> Dans ce texte fondateur de la théorie de l’information, Shannon définit la notion de communication, la fonde sur celle de probabilité, définit le terme bit comme mesure logarithmique de l’information, ainsi que la notion d’entropie informatique (par analogie avec celle de Boltzmann en physique statistique). Il définit aussi mathématiquement la capacité d’un canal de transmission : on peut transmettre l’information de façon fiable tant que le débit ne dépasse pas cette capacité – le bruit présent dans le canal ne limite pas la qualité de la communication, mais uniquement le débit de transmission.</p>
• Complexity of the computation of dominating sets in graphs
  
  • Hudry Olivier
  , 2018.
• Mathématiques à/en portée
  
  • Zayana Karim
  Au fil des maths, APMEP, 2018. Le langage mathématique et le langage musical ont de particulier que les mots, les signes, les symboles, n'y désignent pas seulement des objets : ils les incarnent [1]. Mieux : mathématiques et musique se parlent et se comprennent, au point que leur dialogue fut souvent fructueux : l'étude méthodique du monocorde, attribuée à Pythagore ; la pratique, en amateur, de la guitare par Zorn ; l'usage des probabilités par Xénakis ; l'emploi des transformations géométriques par Bach en sont autant d'exemples. Et si les deux disciplines ont leur grammaire, axiomes et théorèmes dans un cas, solfège et harmonie dans l'autre, elles ne se renouvellent que parce qu'elles savent perpétuellement réinventer et dépasser leurs règles. En voici un aperçu, à la portée du collégien. Par Karim Zayana, inspecteur général, professeur invité à Télécom Paristech.. La portée mathématique du langage musical Quand on lit de la musique, on fait déjà, sans le savoir des mathématiques. Une portée, c'est un axe horizontal-axe des temps, et un axe vertical-axe des notes, lesquelles notes sont indissociablement liées à des fréquences, et donc des nombres. Ajoutons une origine, marquée par la clé qui sert de référence, figure 1. Petit raffinement : l'axe vertical n'est, en vérité, pas gradué linéairement mais logarithmiquement. Quand on franchit un barreau, du DO au RÉ par exemple, on multiplie en fait la fréquence par à peu près 9 8 ⁄. Et quand on passe d'un MI au FA, on la multiplie à peu près par la racine carrée de ce nombre, √ 9 8 ⁄ = 3 2√2 ⁄. Autre fait remarquable : nous venons de décrire ce qui s'apparente à la représentation graphique d'une fonction telle que nous la rencontrons communément aujourd'hui. En cela, la musique avait quelques siècles d'avance sur les mathématiques, qui n'ont adopté ce mode d'explicitation qu'au XVII e siècle. Une portée musicale, nous l'avons dit, c'est un repère. Et la géométrie s'invite dès lors spontanément. On va reconnaître, sur certaines partitions, les effets de transformations du plan : translations et symétries ou association des deux. La translation horizontale traduit un décalage temporel, qu'on retrouve dans l'écriture du canon. La translation verticale est, elle, plus ou moins une transposition, c'est-à-dire que l'on Figure 1 Figure 2
• Experimental investigation of practical unforgeable quantum money
  
  • Bozzio Mathieu
  • Orieux Adeline
  • Trigo Vidarte Luis
  • Zaquine Isabelle
  • Kerenidis Iordanis
  • Diamanti Eleni
  npj Quantum Information, Nature, 2018, 4 (1). Wiesner's unforgeable quantum money scheme is widely celebrated as the first quantum information application. Based on the no-cloning property of quantum mechanics, this scheme allows for the creation of credit cards used in authenticated transactions offering security guarantees impossible to achieve by classical means. However, despite its central role in quantum cryptography, its experimental implementation has remained elusive because of the lack of quantum memories and of practical verification techniques. Here, we experimentally implement a quantum money protocol relying on classical verification that rigorously satises the security condition for unforgeability. Our system exploits polarization encoding of weak coherent states of light and operates under conditions that ensure compatibility with state-of-the-art quantum memories. We derive working regimes for our system using a security analysis taking into account all practical imperfections. Our results constitute a major step towards a real-world realization of this milestone protocol. (10.1038/s41534-018-0058-2)
  DOI : 10.1038/s41534-018-0058-2
• A Generative Model for Non-Intrusive Load Monitoring in Commercial Buildings
  
  • Henriet Simon
  • Şimşekli Umut
  • Fuentes Benoît
  • Richard Gael
  Energy and Buildings, Elsevier, 2018. In the recent years, there has been an increasing academic and industrial interest for analyzing the electrical consumption of commercial buildings. Whilst having similarities with the Non Intrusive Load Monitoring (NILM) tasks for residential buildings, the nature of the signals that are collected from large commercial buildings introduces additional difficulties to the NILM research causing existing NILM approaches to fail. On the other hand, the amount of publicly available datasets collected from commercial buildings is very limited, which makes the NILM research even more challenging for this type of large buildings. In this study, we aim at addressing these issues. We first present an extensive statistical analysis of both commercial and residential measurements from public and private datasets and show important differences. Secondly, we develop an algorithm for generating synthetic current waveforms. We then demonstrate using real measurement and quantitative metrics that both our device model and our simulations are realistic and can be used to evaluate NILM algorithms. Finally, to encourage research on commercial buildings we release a synthesized dataset.
• Blind separation of a large number of sparse sources
  
  • Kervazo C.
  • Bobin Jerome
  • Chenot C.
  Signal Processing, Elsevier, 2018, 150, pp.157-165. Blind Source Separation (BSS) is one of the major tools to analyze multi-spectral data with applications that range from astronomical to biomedical signal processing. Nevertheless, most BSS methods fail when the number of sources becomes large, typically exceeding a few tens. Since the ability to estimate large number of sources is paramount in a very wide range of applications, we introduce a new algorithm, coined block-Generalized Morphological Component Analysis (bGMCA) to specifically tackle sparse BSS problems when large number of sources need to be estimated. Sparse BSS being a challenging nonconvex inverse problem in nature, the role played by the algorithmic strategy is central, especially when many sources have to be estimated. For that purpose, the bGMCA algorithm builds upon block-coordinate descent with intermediate size blocks. Numerical experiments are provided that show the robustness of the bGMCA algorithm when the sources are numerous. Comparisons have been carried out on realistic simulations of spectroscopic data. (10.1016/j.sigpro.2018.04.006)
  DOI : 10.1016/j.sigpro.2018.04.006
• Open data in the hotel industry: leveraging forthcoming events for hotel recommendation
  
  • Al-Ghossein Marie
  • Abdessalem Talel
  • Barré Anthony
  Information Technology \& Tourism, 2018.
• Phase evolution of the direct detection noise figure of a nondegenerate fiber phase-sensitive amplifier
  
  • Labidi Tarek
  • Fsaifes Ihsan
  • Xie Weilin
  • Chatterjee Debanuj
  • Goldfarb Fabienne
  • Bretenaker Fabien
  Optics Letters, Optical Society of America - OSA Publishing, 2018, 43 (18), pp.4546. We experimentally investigate the evolution of the direct detection noise figure of a nondegenerate phase-sensitive amplifier based on a nonlinear fiber, as a function of the relative phase between the signal, idler, and pump, all other parameters remaining fixed. The use of a fiber with a high stimulated Brillouin scattering threshold permits us to investigate the full range of phase-sensitive gain and noise figure without pump dithering. Good agreement is found with theory, both for signal only and combined signal and idler direct detections. (10.1364/OL.43.004546)
  DOI : 10.1364/OL.43.004546
• Uniformly Projected RCQD QAM: A Low-Complexity Signal Space Diversity Solution over Fading Channels With or Without Erasures
  
  • Arbi Tarak
  • Geller Benoit
  • Yang Jianxiao
  • Abdel Nour Charbel
  • Rioul Olivier
  IEEE Transactions on Broadcasting, Institute of Electrical and Electronics Engineers, 2018. —Rotated and cyclic Q-delayed (RCQD) M-QAM (Quadrature Amplitude Modulation) provides signal space diversity and thus improves system performance over fading channels. However, previously published RCQD solutions were designed without fully considering the high demodulation complexity which prohibits wider applications. In this paper, a complete solution is proposed to reduce complexity for both the modulator and the demodulator. This solution uses a series of rotation angles α =arctan(1/ √ M) which bring many interesting properties to the RCQD signals. A simplified sphere demapping algorithm is derived for fading channels with and without erasure events. In contrast to the sphere-decoder used for MIMO detection, the radius of the proposed sphere-demapper involves an exact amount of constellation points, thereby ensuring to perform the soft demapping operation successfully. Moreover, when either the in-phase (I) or the quadrature component (Q) is erased, the proposed demapping algorithm performs as well as the full-complexity Max-Log algorithm, with a reduced complexity. Compared to the solution currently used in DVB-T2, the proposed method reduces tremendously the computational complexity while still achieving similar performance over fading channels and even better performance over fading erasure channels. (10.1109/TBC.2018.2811618)
  DOI : 10.1109/TBC.2018.2811618
• Incidence of paradoxical reactions in patients treated with tocilizumab for rheumatoid arthritis: Data from the French registry REGATE
  
  • Terreaux William
  • Masson Claire
  • Eschard Jean-Paul
  • Bardin Thomas
  • Constantin Arnaud
  • Le Dantec Loïc
  • Marcelli Christian
  • Perdriger Aleth
  • Scotto Di Fazano Claire
  • Wendling Daniel
  • Sibilia Jean
  • Morel Jacques
  • Salmon Jean
  Joint Bone Spine, Elsevier Masson, 2018, 85 (1), pp.53-57. Objectives Assess the frequency of paradoxical reactions encountered in daily practice under tocilizumab, using the REGATE (Registry-RoActemra) registry. The secondary objectives were to determine the type of paradoxical reaction and the consequences of these reactions. Methods The REGATE registry is an independent prospective registry, promoted by the French Society of Rheumatology, consisting of patients treated with tocilizumab for rheumatoid arthritis. The paradoxical reaction was retained if it was a paradoxical precipitation of a condition for which tocilizumab was indicated, if tocilizumab was being used for an alternative indication, and if it appeared after at least one tocilizumab infusion. Results Among the 1491 patients included with at least one follow-up visit (3429 patient-years), a paradoxical reaction occurred in 9 patients (0.60% of patients; 2.62/1000 patient-years). These were 7 de novo pathologies (3 vasculitis, 3 uveitis, 1 lupus) and 2 exacerbations of pre-existing conditions (1 vasculitis, 1 lupus). Permanent discontinuation of tocilizumab was chosen for 5 patients. Conclusions In the REGATE registry, the occurrence of paradoxical reactions in patients treated with tocilizumab was rare. (10.1016/j.jbspin.2017.01.002)
  DOI : 10.1016/j.jbspin.2017.01.002
• Mean value coordinates for quad cages in 3D
  
  • Thiery Jean-Marc
  • Memari Pooran
  • Boubekeur Tamy
  ACM Transactions on Graphics, Association for Computing Machinery, 2018.
• DyBED: An Efficient Algorithm for Updating Betweenness Centrality in Directed Dynamic Graphs
  
  • Chehreghani Mostafa Haghir
  • Bifet Albert
  • Abdessalem Talel
  , 2018, pp.2114-2123.
• Quarante ans d’imagerie satellitaire radar
  
  • Nicolas Jean-Marie
  • Tupin Florence
  Revue Française de Photogrammétrie et de Télédétection, Société Française de Photogrammétrie et de Télédétection, 2018.
• Managing 'proto-ecosystems' - two smart mobility case studies
  
  • Marcocchia Giulia
  • Maniak Rémi
  International Journal of Automotive Technology and Management, Inderscience, 2018, 18 (3), pp.209-228. This paper considers how ecosystem-based research projects can be managed for a successful deployment of systemic and disruptive innovation. Such projects are defined as assignments in which heterogeneous organisations must invest upfront, aiming at co-constructing a systemic offer with shared interest, shared uncertainty and high economic, environmental and social impacts. Innovation management, ecosystem, and public-private partnership literatures have been investigated, as well as two European Commission funded research projects aimed at smart mobility infrastructure development. Results show these projects are both critical and disappointing for each player. We explain this contradiction of value perception showing that partners need such ecosystem projects to go forward and update their competences and roadmaps, but that the observed project management approach hampers the collectively built learning and the evolution of the strategic agenda of each partner. In conclusion, we define the concept of proto-ecosystem as an intermediary 'management object' for innovation management, and point out implications to manage such projects in order to unfold their whole potential. (10.1504/IJATM.2018.093413)
  DOI : 10.1504/IJATM.2018.093413
• Method, device and computer program for encapsulating media data into a media file
  
  • Denoual Franck
  • Mazé Frédéric
  • Le Feuvre J.
  • Ouedraogo Nael
  , 2018.
• Musical Descriptions Based on Formal Concept Analysis and Mathematical Morphology
  
  • Agon Carlos
  • Andreatta Moreno
  • Atif Jamal
  • Bloch Isabelle
  • Mascarade Pierre
  , 2018, pp.105-119. In the context of mathematical and computational representations of musical structures, we propose algebraic models for formalizing and understanding the harmonic forms underlying musical compositions. These models make use of ideas and notions belonging to two algebraic approaches: Formal Concept Analysis (FCA) and Mathematical Morphology (MM). Concept lattices are built from interval structures whereas mathematical morphology operators are subsequently defined upon them. Special equivalence relations preserving the ordering structure of the lattice are introduced in order to define musically relevant quotient lattices modulo congruences. We show that the derived descrip-tors are well adapted for music analysis by taking as a case study Ligeti's String Quartet No. 2. (10.1007/978-3-319-91379-7_9)
  DOI : 10.1007/978-3-319-91379-7_9
• Profitable Bandits
  
  • Achab Mastane
  • Clémençon Stéphan
  • Garivier Aurélien
  Proceedings of Machine Learning Research, PMLR, 2018, 95, pp.694-709. Originally motivated by default risk management applications, this paper investigates a novel problem, referred to as the profitable bandit problem here. At each step, an agent chooses a subset of the K ≥ 1 possible actions. For each action chosen, she then respectively pays and receives the sum of a random number of costs and rewards. Her objective is to maximize her cumulated profit. We adapt and study three well-known strategies in this purpose, that were proved to be most efficient in other settings: kl-UCB, Bayes-UCB and Thompson Sampling. For each of them, we prove a finite time regret bound which, together with a lower bound we obtain as well, establishes asymptotic optimality in some cases. Our goal is also to compare these three strategies from a theoretical and empirical perspective both at the same time. We give simple, self-contained proofs that emphasize their similarities, as well as their differences. While both Bayesian strategies are automatically adapted to the geometry of information, the numerical experiments carried out show a slight advantage for Thompson Sampling in practice.
• Mass volume curves and anomaly ranking
  
  • Clémençon Stéphan
  • Thomas Albert
  Electronic Journal of Statistics, Shaker Heights, OH : Institute of Mathematical Statistics, 2018, 12 (2), pp.2806-2872. (10.1214/18-EJS1474)
  DOI : 10.1214/18-EJS1474
• Une approche par patchs, multi-atlas, itérative pour la segmentation du cortex cérébral en IRM néonatale
  
  • Tor-Díez Carlos
  • Passat Nicolas
  • Bloch Isabelle
  • Faisan Sylvain
  • Bednarek Nathalie
  • Rousseau François
  , 2018. L’analyse des structures cérébrales chez le nouveau-né constitue un enjeu de santé majeur, notamment en cas de prématurité, afin de disposer d’informations prédictives sur le développement de l’enfant. Le cortex est, en particulier, une structure d’intérêt, observable en IRM (imagerie par résonance magnétique). Les données IRM néonatales présentent toutefois des spécificités qui les rendent complexes à traiter. Dans ce contexte, les approches multi-atlas constituent une stratégie efficace, tirant parti de données traitées préalablement. La méthode proposée dans cet article repose sur une telle stratégie multi-atlas. Elle s’appuie notamment sur deux paradigmes : l’utilisation d’un modèle non local à base de patchs, et l’utilisation d’un schéma d’optimisation itératif. L’usage couplé de ces deux concepts permet notamment de considérer des patchs liés à l’image ainsi qu’à sa segmentation courante. Cette stratégie, comparée à de précédentes méthodes multi-atlas de la littérature, aboutit à des résultats de segmentation corticale robustes.
• Segmentation of pelvic vessels in pediatric MRI using a patch based learning approach
  
  • Virzi Alessio
  • Gori Pietro
  • Muller Cécile
  • Mille Eva
  • Peyrot Quoc
  • Berteloot Laureline
  • Boddaert Nathalie
  • Sarnacki Sabine
  • Bloch Isabelle
  , 2018, pp.617.
• Transcription of Spanish Historical Handwritten Documents with Deep Neural Networks
  
  • Granell Emilio
  • Chammas Edgard
  • Likforman-Sulem Laurence
  • Martínez-Hinarejos Carlos-D
  • Mokbel Chafic
  • Cirstea Bogdan
  Journal of Imaging, MDPI, 2018, 4 (1), pp.22.
• A Smooth Primal-Dual Optimization Framework for Nonsmooth Composite Minimization
  
  • Tran-Dinh Quoc
  • Fercoq Olivier
  • Cevher Volkan
  SIAM Journal on Optimization, Society for Industrial and Applied Mathematics, 2018, 28 (1), pp.96-134. We propose a new first-order primal-dual optimization framework for a convex optimization template with broad applications. Our optimization algorithms feature optimal convergence guarantees under a variety of common structure assumptions on the problem template. Our analysis relies on a novel combination of three classic ideas applied to the primal-dual gap function: smoothing, acceleration, and homotopy. The algorithms due to the new approach achieve the best known convergence rate results, in particular when the template consists of only non-smooth functions. We also outline a restart strategy for the acceleration to significantly enhance the practical performance. We demonstrate relations with the augmented Lagrangian method and show how to exploit the strongly convex objectives with rigorous convergence rate guarantees. We provide numerical evidence with two examples and illustrate that the new methods can outperform the state-of-the-art, including Chambolle-Pock, and the alternating direction method-of-multipliers algorithms.