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A class of Weiss-Weinstein bounds and its relationship with the Bobrovsky-Mayer-Wolf-Zakai bounds
No full textInternational audienceA fairly general class of Bayesian " large-error " lower bounds of the Weiss-Weinstein family, essentially free from regularity conditions on the probability density functions support, and for which a limiting form yields a generalized Bayesian Cramér-Rao bound (BCRB), is introduced. In a large number of cases, the generalized BCRB appears to be the Bobrovsky-Mayer-Wolf-Zakai bound (BMZB). Interestingly enough, a regularized form of the Bobrovsky-Zakai bound (BZB), applicable when the support of the prior is a constrained parameter set, is obtained. Modified Weiss-Weinstein bound and BZB which limiting form is the BMZB are proposed, in expectation of an increased tightness in the threshold region. Some of the proposed results are exemplified with a reference problem in signal processing: the Gaussian observation model with parameterized mean and uniform prior
Tests d’hypothèses statistiquement et algorithmiquement efficaces de similarité et de dépendance
No full textThe dissertation presents novel statistically and computationally efficient hypothesis tests for relative similarity and dependency, and precision matrix estimation. The key methodology adopted in this thesis is the class of U-statistic estimators. The class of U-statistics results in a minimum-variance unbiased estimation of a parameter.The first part of the thesis focuses on relative similarity tests applied to the problem of model selection. Probabilistic generative models provide a powerful framework for representing data. Model selection in this generative setting can be challenging. To address this issue, we provide a novel non-parametric hypothesis test of relative similarity and test whether a first candidate model generates a data sample significantly closer to a reference validation set.Subsequently, the second part of the thesis focuses on developing a novel non-parametric statistical hypothesis test for relative dependency. Tests of dependence are important tools in statistical analysis, and several canonical tests for the existence of dependence have been developed in the literature. However, the question of whether there exist dependencies is secondary. The determination of whether one dependence is stronger than another is frequently necessary for decision making. We present a statistical test which determine whether one variables is significantly more dependent on a first target variable or a second.Finally, a novel method for structure discovery in a graphical model is proposed. Making use of a result that zeros of a precision matrix can encode conditional independencies, we develop a test that estimates and bounds an entry of the precision matrix. Methods for structure discovery in the literature typically make restrictive distributional (e.g. Gaussian) or sparsity assumptions that may not apply to a data sample of interest. Consequently, we derive a new test that makes use of results for U-statistics and applies them to the covariance matrix, which then implies a bound on the precision matrix.Cette thèse présente de nouveaux tests d’hypothèses statistiques efficaces pour la relative similarité et dépendance, et l’estimation de la matrice de précision. La principale méthodologie adoptée dans cette thèse est la classe des estimateurs U-statistiques.Le premier test statistique porte sur les tests de relative similarité appliqués au problème de la sélection de modèles. Les modèles génératifs probabilistes fournissent un cadre puissant pour représenter les données. La sélection de modèles dans ce contexte génératif peut être difficile. Pour résoudre ce problème, nous proposons un nouveau test d’hypothèse non paramétrique de relative similarité et testons si un premier modèle candidat génère un échantillon de données significativement plus proche d’un ensemble de validation de référence.La deuxième test d’hypothèse statistique non paramétrique est pour la relative dépendance. En présence de dépendances multiples, les méthodes existantes ne répondent qu’indirectement à la question de la relative dépendance. Or, savoir si une dépendance est plus forte qu’une autre est important pour la prise de décision. Nous présentons un test statistique qui détermine si une variable dépend beaucoup plus d’une première variable cible ou d’une seconde variable.Enfin, une nouvelle méthode de découverte de structure dans un modèle graphique est proposée. En partant du fait que les zéros d’une matrice de précision représentent les indépendances conditionnelles, nous développons un nouveau test statistique qui estime une borne pour une entrée de la matrice de précision. Les méthodes existantes de découverte de structure font généralement des hypothèses restrictives de distributions gaussiennes ou parcimonieuses qui ne correspondent pas forcément à l’étude de données réelles. Nous introduisons ici un nouveau test utilisant les propriétés des U-statistics appliqués à la matrice de covariance, et en déduisons une borne sur la matrice de précision
Effect of resistivity ratio on energy storageand dielectric relaxation properties of 0–3 dielectriccomposites
No full textInternational audienceThe brick wall model for ceramics was employed to simulate the dielectricresponse of 0–3 composites. By applying equivalent circuit method, the effectivefield, energy storage density and effective dielectric permittivity of the compositeswere studied. The results indicate that the resistivity ratio between thematrix and the fillers plays a crucial role for all these properties. A compositewith slightly less resistive matrix with respect to the fillers favors energy storageand maintains large effective dielectric permittivity providing a useful guidelinefor improved performances. The low effective dielectric permittivity usuallymeasured on ceramic–polymer 0–3 dielectric composites can also be understoodbased on our simulation results
Upper and lower bounds for the ergodic capacity of MIMO Jacobi fading channels
No full textInternational audienceIn multi-(core/mode) optical fiber communication, the transmission channel can be modeled as a complex sub-matrix of the Haar-distributed unitary matrix (complex Jacobi unitary ensemble). In this letter, we present new analytical expressions of the upper and lower bounds for the ergodic capacity of multiple-input multiple-output Jacobi-fading channels. Recent results on the determinant of the Jacobi unitary ensemble are employed to derive a tight lower bound on the ergodic capacity. We use Jensen's inequality to provide an analytical closed-form upper bound to the ergodic capacity at any signal-to-noise ratio (SNR). Closed-form expressions of the ergodic capacity, at low and high SNR regimes, are also derived. Simulation results are presented to validate the accuracy of the derived expressions
Hardware Automated Datafow Deployment of CNNs
No full textDeep Convolutional Neural Networks (CNNs) are the state of the art systems for image classification and scene understating. However, such techniques are computationally intensive and involve highly regular parallel computation. CNNs can thus benefit from a significant acceleration in execution time when running on fine grain programmable logic devices. As a consequence, several studies have proposed FPGA-based accelerators for CNNs. However, because of the huge amount of the required hardware resources, none of these studies directly was based on a direct mapping of the CNN computing elements onto the FPGA physical resources. In this work, we demonstrate the feasibility of this so-called direct hardware mapping approach and discuss several associated implementation issues. As a proof of concept, we introduce the haddoc2 open source tool, that is able to automatically transform a CNN description into a platform independent hardware description for FPGA implementation
Mechanically Pattern-Reconfigurable Bended Horn Antenna for High-Power Applications
No full textInternational audienceIn this letter, a mechanically pattern-reconfigurable antenna is presented to achieve various half-power beamwidth for high-power applications. A bended H-sectoral horn antenna with two movable metallic flaps is presented to change the aperture length in the H-plane direction in order to provide reconfigurable half-power beamwidth starting from 58.7° to 16.5°. Moreover, the horn radiating aperture is integrated into a corrugated ground plane to increase the E-plane radiation pattern gain. The antenna is energized with an effective power source of 1.9 kW showing the capability of the antenna to handle high-power microwave signals within a certain frequency range. © 2002-2011 IEEE
Combining the Viable System Model and Kotter’s 8 Steps for Multidepartment Integration in Hospitals
No full textInternational audienceIntegration between different departments is a major challenge for hospitals. It is considered as a key step towards greater efficiency. Yet research in industrial engineering does not provide satisfactory answers to this issue. Multi-departments issues are under-investigated and the implementation of recommendations is scarce. In this article, we focus on the first phases of a change program aiming at the better integration of a hospital sub-system. We propose an original methodological combination: Stafford Beer’s Viable System Model, an organizational cybernetics model, is coupled with John Kotter’s 8 steps for leading change, a change management method. We implement this approach in an action-research project in a French hospital’s outpatient chemotherapy sub-system. The method allows us to diagnose structural issues in the system, to build a change program and to launch its implementation effectively. The first elements of an integrated vision are already present in the hospital.L'intégration des différents services en un ensemble coordonné est un défi important pour les hôpitaux afin d'augmenter leur efficience. A ce jour, les solutions apportées par la recherche en génie industriel pour aider les praticiens à y parvenir sont insuffisantes. Les problématiques multi-services sont insuffisamment traitées et l'implémentation des recommandations est rare. Cet article s'intéresse aux premières phases d'un programme de changement visant à renforcer l'intégration d'un sous-système hospitalier. Nous proposons une combinaison méthodologique originale : le Viable System Model, un modèle cybernétique d'organisation, est couplé à une méthode de conduite du changement, les 8 étapes de John Kotter. Cette approche, implémentée en recherche-action sur la délivrance de chimiothérapies ambulatoires dans un hôpital français, nous permet de diagnostiquer les problèmes structurels de l'organisation, de construire un programme de changement et de le lancer efficacement. Les premiers éléments d'une vision intégrés sont déjà présents dans l'hôpital. Abstract – Integration between different departments is a major challenge for hospitals. It is considered as a key step towards greater efficiency. Yet research in industrial engineering does not provide satisfactory answers to this issue. Multi-departments issues are under-investigated and the implementation of recommendations is scarce. In this article, we focus on the first phases of a change program aiming at the better integration of a hospital subsystem. We propose an original methodological combination: Stafford Beer's Viable System Model, an organizational cybernetics model, is coupled with John Kotter's 8 steps for leading change, a change management method. We implement this approach in an action-research project in a French hospital's outpatient chemotherapy subsystem. The method allows us to diagnose structural issues in the system, to build a change program and to launch its implementation effectively. The first elements of an integrated vision are already present in the hospital. Mots clés – Viable System Model, intégration, gestion hospitalière, conduite du changement, recherche-action
Interpolation Methods for Binary and Multivalued Logical Quantum Gate Synthesis
No full textInternational audienceA method for synthesizing quantum gates is presented based on interpolation methods applied to operators in Hilbert space. Starting from the diagonal forms of specific generating seed operators with non-degenerate eigenvalue spectrum one obtains for arity-one a family of logical operators corresponding to the one-argument logical connectives. Scaling up to n-arity gates is obtained by using the Kronecker product and unitary transformations. The quantum version of the Fourier transform of Boolean function is presented and a method for Reed-Muller decomposition is derived. The common control gates can be easily obtained by considering the logical correspondence between the control logic operator and the binary logic operator. A new polynomial and exponential formulation of the Toffoli gate is presented. The method has parallels to quantum gate-T optimization methods using powers of multilinear operator polynomials. The method is then applied naturally to alphabets greater than two for multi-valued logical gates used for quantum Fourier transform, min-max decision circuits and multivalued adders
20 Years of Reality Gap: a few Thoughts about Simulators in Evolutionary Robotics
No full textInternational audienceSimulators in Evolutionary Robotics (ER) are often considered as a "temporary evil" until experiments can be conducted on real robots. Yet, aaer more than 20 years of ER, most experiments still happen in simulation and nothing suggests that this situation will change in the next few years. In this short paper, we describe the requirements of ER from simulators, what we tried, and how we successfully crossed the "reality gap" in many experiments. We argue that future simulators need to be able to estimate their conndence when they predict a tness value, so that behaviors that are not accurately simulated can be avoided