INRIA a CCSD electronic archive server

    Heterogeneous Face Recognition with CNNs

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    International audienceHeterogeneous face recognition aims to recognize faces across different sensor modalities. Typically, gallery images are normal visible spectrum images, and probe images are infrared images or sketches. Recently significant improvements in visible spectrum face recognition have been obtained by CNNs learned from very large training datasets. In this paper, we are interested in the question to what extent the features from a CNN pre-trained on visible spectrum face images can be used to perform heterogeneous face recognition. We explore different metric learning strategies to reduce the discrepancies between the different modalities. Experimental results show that we can use CNNs trained on visible spectrum images to obtain results that are on par or improve over the state-of-the-art for heterogeneous recognition with near-infrared images and sketches

    Analysis of a Generalized Dispersive Model Coupled to a DGTD Method with Application to Nanophotonics

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    International audienceIn this paper, we are concerned with the numerical modelling of the propagation of electromagnetic waves in dispersive materials for nanophotonics applications. We focus on a generalized model that allows for the description of a wide range of dispersive media. The underlying differential equations are recast into a generic form, and we establish an existence and uniqueness result. We then turn to the numerical treatment and propose an appropriate discontinuous Galerkin time domain framework. We obtain the semidiscrete convergence and prove the stability (and to a larger extent, convergence) of a Runge--Kutta 4 fully discrete scheme via a technique relying on energy principles. Finally, we validate our approach through two significant nanophotonics test cases

    Large-scale 3D EM modeling with a Block Low-Rank multifrontal direct solver

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    International audienceWe put forward the idea of using a Block Low-Rank (BLR) multifrontal direct solver to efficiently solve the linear systems of equations arising from a finite-difference discretization of the frequency-domain Maxwell equations for 3-D electromagnetic (EM) problems. The solver uses a low-rank representation for the off-diagonal blocks of the intermediate dense matrices arising in the multifrontal method to reduce the computational load. A numerical threshold, the so-called BLR threshold, controlling the accuracy of low-rank representations was optimized by balancing errors in the computed EM fields against savings in floating point operations (flops). Simulations were carried out over large-scale 3-D resistivity models representing typical scenarios for marine controlled-source EM surveys, and in particular the SEG SEAM model which contains an irregular salt body. The flop count, size of factor matrices and elapsed run time for matrix factorization are reduced dramatically by using BLR representations and can go down to, respectively, 10, 30 and 40 per cent of their full-rank values for our largest system with N = 20.6 million unknowns. The reductions are almost independent of the number of MPI tasks and threads at least up to 90 × 10 = 900 cores. The BLR savings increase for larger systems, which reduces the factorization flop complexity from O(N2) for the full-rank solver to O(Nm) with m = 1.4–1.6. The BLR savings are significantly larger for deep-water environments that exclude the highly resistive air layer from the computational domain. A study in a scenario where simulations are required at multiple source locations shows that the BLR solver can become competitive in comparison to iterative solvers as an engine for 3-D controlled-source electromagnetic Gauss–Newton inversion that requires forward modelling for a few thousand right-hand sides

    La philosophie des techniques revue à l'aune de l'internet et du numérique

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    La fin des frais d'itinérance dans l'Union européenne en 2017, est-ce la panacée ?

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    Depuis le 15 juin 2017, les frais d'itinérance sont interdits sur l'Union européenne. L'itinérance sans frais est-elle totale? Les utilisateurs sont-ils nécessairement bénéficiaires grâce à cette mesure? Nous discutons ici les risques associés

    Next Step for Big Data Infrastructure and Analytics for the Surveillance of the Maritime Traffic from AIS & Sentinel Satellite Data Streams

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    International audienceThe surveillance of the maritime traffic is a major issue for security and monitoring issues. Spaceborne technologies, especially satellite AIS ship tracking and high-resolution imaging, open new avenues to address these issues. Current operational systems cannot fully benefit from the available and upcoming multi-source data streams. In this context, SESAME initiative aims to develop new big-data-oriented approaches to deliver novel solutions for the management, analysis and visualisation of multi-source satellite data streams going beyond the CLS implementation. Targeted at the automatic generation and documenting of early warnings, our key originality lies in a big-data approach to jointly address these challenges based on the complementarity of the scientific and operational expertise gathered in the consortium: big-data platforms, mining strategies for time series and trajectory data, Sat-AIS signal analysis, high-resolution satellite imaging

    Control Synthesis for Stochastic Switched Systems using the Tamed Euler Method

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    In this paper, we explain how, under the one-sided Lipschitz (OSL) hypothesis, one can find an error bound for a variant of the Euler-Maruyama approximation method for stochastic switched systems. We then explain how this bound can be used to control stochastic switched switched system in order to stabilize them in a given region. The method is illustrated on several examples of the literature

    Semantic interactive ontology matching: synergistic combination of techniques to improve the set of candidate correspondences

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    silva2017aInternational audienceOntology Matching is the task of finding a set of entity correspondences between a pair of ontologies, i.e. an alignment. It has been receiving a lot of attention due to its broad applications. Many techniques have been proposed, among which the ones applying interactive strategies. An interactive ontology matching strategy uses expert knowledge towards improving the quality of the final alignment. When these strategies are based on the expert feedback to validate correspondences, it is important to establish criteria for selecting the set of correspondences to be shown to the expert. A bad definition of this set can prevent the algorithm from finding the right alignment or it can delay convergence. In this work we present techniques which, when used simultaneously, improve the set of candidate correspondences. These techniques are incorporated in an interactive ontology matching approach, called ALINSyn. Experiments successfully show the potential of our proposal

    Multi-View Design for Cyber-Physical Systems

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    International audienceCyber-Physical Systems are complex systems made of various and heterogeneous subsystems; they have different aspects and each aspect has its own requirements and properties to be satisfied. Model-Driven Engineering (MDE) is a promising approach used to design and analyze complex systems on different levels and diverse views. CPS designers take many factors into account due to the complexity and diversity of current CPS systems. The designers have their own individual experience and specific viewpoint; they may use different models and languages to describe various domains, different models and languages lead to a complex coherency management. Therefore, how to promote the coherency of a whole system and ensure all subsystems can work together is an important concrete issue. To resolve this issue, we introduce a unified modeling methodology which can coordinate different models and languages with a multi-view approach. Indeed, we expect multi-view approaches to help handling system coherency. Hence, we focus on providing a high-level modeling methodology with multi-view that (i) Coordinates different languages of models and diverse tools. (ii) Ensures engineering-wide collaboration by sharing the same reference architecture. (iii) Handles the complexity of systems and architectures, using unified viewpoints to model the whole systems with top-down refinement. (iv) Supports different formal methods to verify critical elements. (v) Backtraces verification results to models

    A branching process model of heterogeneous DNA damages caused by radiotherapy in in vitro cell cultures

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    International audienceThis paper deals with the dynamic modeling and simulation of cell damage heterogeneity and associated mutant cell phenotypes in the therapeutic responses of cancer cell populations submitted to a radiotherapy session during in vitro assays. Each cell is described by a finite number of phenotypic states with possible transitions between them. The population dynamics is then given by an age-dependent multi-type branching process. From this representation, we obtain formulas for the average size of the global survival population as well as the one of subpopulations associated with 10 mutation phenotypes. The proposed model has been implemented into Matlab© and the numerical results corroborate the ability of the model to reproduce four major types of cell responses: delayed growth, anti-proliferative, cytostatic and cytotoxic
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