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Miniaturized gas chromatography for space exploration: A 50 years history
No full textInternational audienceSince the beginning of the in situ exploration of alien worlds in the solar system, the characterization of the chemical composition in volatile materials and organic molecules is among the top priorities. Indeed, these compounds learn us about the origin and history of these world, their potential for habitability, and somehow the nature of resources they could provide, especially for future inhabited exploration. Among the chemical analytical techniques existing, gas chromatography was preferentially used as it is a robust instrumentation that can be used in many environments. Obviously, as the constraints of spacecraft accommodation require for light and small instruments, gas chromatographs have to meet these constraints and to be miniaturized compared to the laboratory set-up. This article tells the story of gas chromatography for space exploration and give information about its miniaturization
Scalar near-field focusing in lossy media
No full textInternational audienceAntenna near-field focusing is a research topic that is recently attracting attention, due to its impact on a wide number of trending applications. In this communication we propose a methodology based on convex optimization to focus the scalar field radiated by planar continuous apertures. The methodology is capable to focus the field inside piecewise stratified media and is supported by an easy-to-implement MATLAB package. In addition, we apply specific optimization goals which render the resulting aperture distributions realizable. © 2017 IEEE
A 3-D Wide-Band Set-up for Over-The-Air Test in Anechoic Chamber
No full textInternational audienceIn this paper we present a 3D wide-band measurement bench for Over-the-Air (OTA) tests. The setup is composed by twelve double-polarized antennas, placed around the Zone Under Test (ZUT), on three different elevation planes. A characterization of the ZUT was performed in order to assess the differences, in terms of amplitude and phase of the incident field, according to the frequency considered
SMTCoq: A plug-in for integrating SMT solvers into Coq
No full textInternational audienceThis paper describes SMTCoq, a plug-in for the integration of external solvers into the Coq proof assistant. Based on a checker for generic first-order proof certificates fully implemented and proved correct in Coq, SMTCoq offers facilities to check answers from external SAT and SMT solvers and to increase Coq's automation using such solvers, all in a safe way. The current version supports proof certificates produced by the SAT solver ZChaff, for propositional logic, and the SMT solvers veriT and CVC4, for the quantifier-free fragment of the combined theory of fixed-size bit vectors, functional arrays with extensionality, linear integer arithmetic, and uninterpreted function symbols
Robustesse de la commande pr´edictive explicite
No full textThe control design techniques for linear or hybrid systems with constraints lead often to off-line state-space partitions with non-overlapping convex polyhedral regions. This corresponds to a piecewise affine (PWA) state feedback control laws associated to polyhedral partition of the state-space. Such control laws can be effectively implemented on hardwares for real-time control applications. However, the robustness of the explicit solutions depends on the accuracy of the mathematical model of the dynamical systems. The uncertainties in the system model poses serious challenges concerning the stability and implementation of the piecewise affine control laws. Motivated by the challenges facing the explicit solutions for the uncertainties in the dynamical systems, this thesis is mostly related to their analysis and re-design. The first part of this thesis aims to compute robustness margins for a given nominal PWA control law obtained for a linear discrete-time system. Classical Robustness margin i.e., gain margin and phase margin, considers the gain variation and phase variation of the model for which the stability of the closed loop is preserved.The second part of the thesis aims to consider perturbation in the representation of the vertices of the polyhedral regions. The quantized state-space partitions lose some of the important property of the explicit controllers: “non-overlapping”, “convexity” and “invariant” characterization. Two different sets called vertex-sensitivity and sensitivity margin are defined and determined to characterize admissible perturbation preserving the non-overlapping and the invariance property of the controller respectively. The third part analyse the complexity of the explicit solutions in terms of computational time and memory storage. Sequential and parallel evaluations of the PWA functions for the Alternating Direction Method of Multiplier (ADMM) algorithm are compared. In addition a comparison of the computational complexity of the parallel evaluations of the PWA functions for the Progressive Hedging Algorithm (PHA) on the Central Processing Unit (CPU) and Graphical Processing Unit (GPU) is made.Les techniques de conception de lois de commande pour les systèmes linéaires ou hybrides avec contraintes conduisent souvent à des partitions de l’espace d’état avec des régions polyédriques convexes. Ceci correspond à des lois de commande par retour d’état affine (PWA) par morceaux associées `a une partition polyédrale de l’espace d’état. De telles lois de commande peuvent être effectivement mises en œuvre sur des plateformes matérielles pour des applications de commande en temps réel. Cependant, la robustesse des solutions explicites dépend de la précision du modèle mathématique des systèmes dynamiques. Les incertitudes dans le modèle du système posent de sérieux défis en ce qui concerne la stabilité et la mise en œuvre des lois de commande affines par morceaux. Motivé par les défis auxquels font face les solutions explicites par rapport aux incertitudes dans les modèles des systèmes dynamiques, cette thèse est principalement axée sur leur analyse et à leur retouche. La première partie de cette thèse vise à calculer les marges de robustesse pour une loi de commande PWA nominale donnée obtenue pour un système de temps discret linéaire. Les marges de robustesse classiques, c’est-à-dire la marge de gain et la marge de phase, considèrent la variation de gain et la variation de phase du modèle pour lequel la stabilité de la boucle fermée est préservée.La deuxième partie de la thèse vise à considérer des perturbations dans la représentation des sommets des régions polyédriques. Les partitions de l’espace d’état quantifiées perdent une partie des propriétés importantes des contrôleurs explicites: “non-chevauchement”, “convexité” et/ou “ invariance”. Deux ensembles différents appelés sensibilité aux sommets et marge de sensibilité sont déterminés pour caractériser les perturbations admissibles, en préservant respectivement la propriété de non-chevauchement et d’invariance du contrôleur. La troisième partie vise à analyser la complexité des solutions explicites en termes de temps de calcul et de mémoire. Une première comparaison entre les évaluations séquentielles et parallèles des fonctions PWA par l’algorithme ADMM (Alternating Direction Method of Multiplier) est faite. Ensuite, la complexité computationnelle des évaluations parallèles des fonctions PWA pour l’algorithme de couverture progressive (PHA) sur l’unit´e centrale de traitement (CPU) et l’unit´e de traitement graphique (GPU) est comparée
Seeing, Sensing and Recognizing Laban Movement Qualities
No full textInternational audienceHuman movement has historically been approached as a functional component of interaction within human computer interaction. Yet movement is not only functional, it is also highly expressive. In our research, we explore how movement expertise as articulated in Laban Movement Analysis (LMA) can contribute to the design of computational models of move-ment's expressive qualities as defined in the framework of Laban Efforts. We include experts in LMA in our design process, in order to select a set of suitable multimodal sensors as well as to compute features that closely correlate to the definitions of Efforts in LMA. Evaluation of our model shows that multimodal data combining positional, dynamic and physiological information allows for a better characterization of Laban Efforts. We conclude with implications for design that illustrate how our methodology and our approach to multimodal capture and recognition of Effort qualities can be integrated to design interactive applications
Dynamically Scaled Immersion and Invariance Adaptive Control for Euler-Lagrange Mechanical Systems
No full textInternational audienc
Online Natural Gradient as a Kalman Filter
No full textWe establish a full relationship between Kalman filtering and Amari's natural gradient in statistical learning. Namely, using an online natural gradient descent on data log-likelihood to evaluate the parameter of a probabilistic model from a series of observations, is exactly equivalent to using an extended Kalman filter to estimate the parameter (assumed to have constant dynamics). In the i.i.d. case, this relation is a consequence of the "information filter" phrasing of the extended Kalman filter. In the recurrent (state space, non-i.i.d.) case, we prove that the joint Kalman filter over states and parameters is a natural gradient on top of real-time recurrent learning (RTRL), a classical algorithm to train recurrent models. This exact algebraic correspondence provides relevant settings for natural gradient hyperparameters such as learning rates or initialization and regularization of the Fisher information matrix
An empirical study of the Algerian dialect of Social network
No full textInternational audienceIn this paper, we present analysis on the use of Algerian dialect in Youtube. To do so, we harvested a corpus of 17M of words. This latter was exploited to extract a comparable Algerian corpus, named CALYOU by aligning pairs of sentences written in Latin and Arabic. This one was built by using a multilingual word embeddings approach. Several experiments have been conducted to fix the parameters of the Continuous Bag of Words approach that will be discussed in this article. The method we proposed achieved a performance of 41% in terms of Recall. In the following, we present several figures on the collected data that led to several unexpected results. In fact, 51% of the vocabulary words are written in Latin script and 82% of the total comments are subject to the phenomenon of code-switching
Fully scalable implementation of a volume coupling scheme for the modeling of multiscale materials
No full textInternational audienceWe present in this paper a new implementation of a multi-scale, multi-model coupling algorithm, with a proposed parallelization scheme for the construction of the coupling terms between the models. This allows one to study such problems with a fully scal-able algorithm on large computer clusters, even when the models and/or the coupling have a high number of degrees of freedom. As an application example, we will consider a system composed by an homogeneous, macroscopic elasto-plastic model and an anisotropic poly-crystalline material model, with a volume coupling based on the Arlequin framework