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Les multiples fonctionnements numériques – algorithmes inclus – qui participent à nos actions quotidiennes se doivent de passer, d’une manière ou d’une autre, par les mains expertes de programmeur·euse·x·s capables de traduire désirs, plans et intuitions en listes d'instructions exécutables par une machine informatique. Pour autant, ce travail concret de façonnage de programmes n’a que peu fait l’objet d’études de terrain détaillées. Si l’on compare les quelques rares enquêtes, importantes mais isolées, à la massivité de la programmation en tant qu’activité située dont les produits ne cessent d’irriguer nos sociétés informatisées, le contraste est inouï : tout reste à faire, ou presque. Prenant acte de la situation, cet article propose quelques outils et analyses pour tenter de la changer. Dans un premier temps, il expose une technique d’investigation, ainsi qu’un formalisme, permettant de rester au plus près du déroulement séquentiel des situations de programmation. Dans un deuxième temps, il analyse des matériaux récoltés selon cette méthode d’enquête – nommée ici sociologie de l’activité de programmation – et suggère qu'une part importante des pratiques de codage consiste, parfois, à aligner des inscriptions afin de renseigner l’état d’entités distantes (interpréteurs, compilateurs, processeurs) et, en retour, indexer un emplacement au sein d’un document numéroté. L’article finit par discuter les perspectives nouvelles sur l‘étude sociale du code induites par cette démarche analytique. The many digital functionings − including algorithms − that contribute to our daily lives must pass, in one way or another, through the expert hands of programmers capable of translating desires, plans, and intuitions into numbered lists of instructions that can be executed by a computing device. However, this concrete work of shaping computer programs has been the topic of few detailed field studies. If one compares the rare, but important, ethnographic works with the massivity of computer programming as a situated activity whose products are constantly irrigating our computerized societies, the contrast is astonishing: everything, almost, remains to be done. Taking note of the situation, this article proposes some tools and analyses to try to change it. First, the paper presents an investigation technique, as well as a formalism, that allows ethnographers to stay as close as possible to the sequential unfolding of computer programming situations. Secondly, the paper analyzes ethnographic materials collected according to this method of investigation − coined here sociology of computer programming activity − and suggests that an important part of coding practices consists, sometimes, in aligning inscriptions in order to inform the state of distant entities (interpreters, compilers, processors) and, in turn, to index a location within a numbered document. The paper ends by discussing the new perspectives on the social study of code induced by this down-to-earth analytical framework.

This paper presents an efficient FE technique based on an automatic local mesh refinement. The solution is calculated with a predefined precision chosen by the user. The precision can be guaranteed for different mechanical variables like displacement, stress, energy density or energy as error indicators for these variables are defined. This paper shows the independence of the solution with respect to the criteria and the initial mesh. Results on the precision of the solution and the efficiency of the method, in terms of computing time, are also given. Three linear elastic examples illustrate the method.

This paper proposes an instrumental variable approach for continuous-time system identification using fractional models with multiple input single output context. This work is an extension of the simplified refined instrumental variable approach (srivcf ) developed for single input-single output fractional model identification (Malti et al. (2008a); Victor et al. (2013)) to the multiple input-single output case. Monte Carlo simulation analysis is used to demonstrate the performance of the proposed approach. A study is then provided to motivate differentiation order estimation, and more specifically, commensurate order estimation.

Assessing the harmfulness of defects based on images is becoming more and more common in industry. Today these defects can be insert in digital twins that aim to replicated in a mechanical model what is observed on a component. We propose a methodology for defect classification and defect labeling in view of fast prediction of their harmfulness by using hyper-reduced order models. Mechanical models studied here are non parametric. This problematic issue is circumvent by introducing a classification of defect. Then, a local hyper-reduced order model is defined in each class of defect. The proposed methodology for the classification, consists in seeing each defect by its mechanical effects more than by its morphology. Each defect is encoded as a point on a Grassmann manifold. This data encoding uses a projection-based hyper-reduction. We restrict our attention to a mechanical modeling of elastic stresses around defects. We show that the hyper-reduced equations are similar to an oblique projection of the finite element prediction. Hence we obtain an upper bound of the approximation error for displacement that depends on a Chordal distance between points on a Grassmann manifold. From the available data set of defects, we have observed that the Grassmann distance is magnifying the Chordal distance between defects. A k-medoids algorithm is used in order to create clusters of defects from a matrix of Grassmann distance between defects. A simulation-based labeling of defect is proposed. This labeling procedure relies on hyper-reduction and a related error indicator. This error indicator measures the discrepancy between the stresses predicted via hyper-reduction and equilibrated stresses. In spite of the large variety of defects in the data set, we show accurate predictions of stresses for most of defects in the test set, while training the clustering and the hyper-reduced order model on a different training set. These accurate results are obtained by combining two contributions for a reduced basis for displacements : macroscopic modes related to a defect-free mechanical problem and elastic fluctuation modes specific to each class of defect. In this paper, we pay particular attention to the compromise to be made between the accuracy of the numerical approximations and the memory space required to save the reduced bases., L’évaluation de la nocivité des défauts à partir d’images est de plus en plus courante dans l’industrie. Aujourd’hui, ces défauts peuvent être insérés dans des jumeaux numériques qui visent à reproduire dans un modèle mécanique ce qui est observé sur un objet. Nous proposons une méthodologie pour la classification et l’étiquetage des défauts en vue de prédire rapidement leur nocivité en utilisant des modèles d’ordre hyperréduits. Les modèles mécaniques étudiés sont non paramétriques. Cette difficulté est contournée par l’introduction d’une classification des défauts. Ensuite, un modèle d’ordre hyperréduit local est défini dans chaque classe de défaut. La méthodologie proposée pour la classification, consiste à voir chaque défaut par ses effets mécaniques plus que par sa morphologie. Chaque défaut est encodé comme un point dans une variété de Grassmann. Ce codage des données utilise un modèle d’ordre réduit par projection. Nous nous limitons notre attention à une modélisation mécanique des contraintes élastiques autour des défauts. Nous montrons qu’une limite supérieure de l’erreur d’approximation pour le déplacement, dépend de la distance Chordal entre les points d’une variété de Grassmann, si une projection de Galerkin est effectuée pour la réduction du modèle. A partir de l’ensemble des données disponibles sur les défauts, nous avons observé que la distance de Grassmann amplifie la distance Chordal entre les défauts. Un algorithme de k-médoïdes est utilisé pour créer des groupes de défauts à partir d’une matrice de la distance de Grassmann entre les défauts. Un étiquetage des défauts basé sur la simulation est proposé. Cette procédure d’étiquetage repose sur l’hyper-réduction et un indicateur d’erreur associé. Cet indicateur d’erreur mesure l’écart entre les contraintes prédites par hyper-réduction et des contraintes équilibrées. Malgré la grande variété de défauts dans l’ensemble de données, nous montrons des prédictions précises des contraintes pour la plupart des défauts dans l’ensemble de test, tout en entraînant la classification et l’hyper-réduction sur un ensemble d’entraînement différent. Ces résultats précis sont obtenus en combinant deux contributions dans une base réduite pour les déplacements : des modes macroscopiques liés à un problème mécanique sans défaut et des modes de fluctuation élastique spécifiques à chaque classe de défaut. Dans cet article, nous accordons une attention particulière au compromis à faire entre la précision des approximations numériques et l’espace mémoire nécessaire pour enregistrer les bases réduites.

Unplugged computing activities became popular at the same time as the introduction of computer science learning at school. In this article we analyze the educational opportunities yielded by computer unplugged activities from the perspective of educational sciences. Theories related to embodied cognition are used here as a framework to analyse unplugged activities such as the robot game, where a student acts as a programmer and the other as a programmable object, such as a robot. This robot game allows us to discuss the potential of unplugged computing activities in connection with the learning of orientation in space, including the transformation from the plane to the three-dimensional space, taking the embodied cognition potential into account., Review of Science, Mathematics and ICT Education, Forthcoming papers

International audience; Belief propagation and variants are the usual decoding algorithms for low density parity check codes. In this paper, successive overrelaxations are applied to increase convergence speed of the decoding process. Performances are reported and improvements over reference algorithms are observed. This technique is also compatible with high speed parallel group decoding involved in modern standards like DVB-S2.

This paper presents how, in compliance with the standard ISO 9241-210:2010, Human Factors activities were implemented in the design of a patient scheduling system in order to decrease the overcrowding in a pediatric emergency department. More specifically, an original method to assess an algorithm with end-users is described. First, a work system analysis was performed through observations and interviews of physicians and nurses from the pediatric emergency department from a French 2965-bed academic hospital. Then, the work system was modeled with a focus on how the patients are arranged and on which criteria the arrangement is based. Those results allowed developing a patients arrangement algorithm along with recommendations to develop a patient scheduling system automatically fed by the existing electronic patient record system. A mock-up of the patient scheduling system has been developed in order to test upstream in the design process the proposed algorithm and a set of icons with healthcare professionals through user testing. Overall, results showed the end-users validated the patients arrangement algorithm and most of the icons. Next steps will be to develop and to implement the patient scheduling system in the pediatric emergency department in order to assess its impact., Cet article présente l'intégration des aspects facteurs humains et ergonomie, conformément à la norme ISO 9241-210 :2010, dans la conception d'un système d'ordonnancement des patients pour les urgences pédiatriques. L'originalité de ce papier réside dans l'adoption de méthodes classiques d'évaluation de produits impliquant les utilisateurs pour l'évaluation d'un algorithme de tri. Une analyse de l'activité, sous forme d'observations et d'entretiens, a été menée dans le service. Ces résultats ont permis de modéliser la gestion du flux patient, d'identifier les indicateurs pertinents et de formuler des recommandations pour la conception du système d'ordonnancement des patients. Ce système prévoit d'être automatiquement alimenté par le système d'information du service des urgences pédiatriques. Une maquette de l'interface a été réalisée pour simuler le fonctionnement de l'algorithme. L'algorithme de tri et les icônes de l'interface associée ont été évalués via des tests utilisateurs, effectués auprès des médecins et infirmiers du service, avec la maquette du système. Les résultats ont validés le fonctionnement de l'algorithme et l'utilisation de certaines icônes. La prochaine étape est d'implémenter l'algorithme et de déployer le système dans le service afin d'évaluer son impact dans la gestion du flux patient.

International audience; The maximum clique problem (MCP) is to determine in a graph a clique (i.e., a complete subgraph) of maximum cardinality. The MCP is notable for its capability of modeling other combinatorial problems and real-world applications. As one of the most studied NP-hard problems, many algorithms are available in the literature and new methods are continually being proposed. Given that the two existing surveys on the MCP date back to 1994 and 1999 respectively, one primary goal of this paper is to provide an updated and comprehensive review on both exact and heuristic MCP algorithms, with a special focus on recent developments. To be informative, we identify the general framework followed by these algorithms and pinpoint the key ingredients that make them successful. By classifying the main search strategies and putting forward the critical elements of the most relevant clique methods, this review intends to encourage future development of more powerful methods and motivate new applications of the clique approaches.

National audience; Dans cet article, nous nous sommes intéressés aux problèmes de reconnaissance noncoopérative de cibles (NCTR) en tant que problème de classification supervisée. Après une présentation du système d'acquisition des profils distance radar et du problème de reconnaissance, suivie d'une étude statistique des données, nous proposons d'utiliser un algorithme des K plus proches voisins (KPPV) dont les performances sont détaillées en fonction du nombre de voisins K, du type de distance utilisée et de la nature des données utilisées (débruitées ou non). Dans un second temps, cet algorithme a été parallélisé sur un processeur many-coeurs (GPU : Graphics Processing Unit). Les opérations arithmétiques et le modèle d'accès mémoire ont été étudiés pour obtenir la meilleure parallélisation des calculs. Enfin, nous terminons par une discussion autour des perspectives envisageables pour la méthode proposée, notamment en s'intéressant à d'autres espaces de représentation ou à d'autres méthodes de classification. ABSTRACT. In this paper, first, we present the problem of Non Cooperative Target Recognition (NCTR) as a supervised classification problem. After a presentation on the radar acquisition system of range profiles and the problem of recognition, followed by a statistical study of data, we use a classical classification method of K Nearest Neighbors (KNN) to do this classification. We explore and compare the performances of this algorithm based on the choice of the distances, the choice of K and the nature of used data (denoised or not). KNN algorithm has been executed initially on CPU with Matlab and then on GPU. Arithmetic operations and memory access pattern has been studied to get the best parallelization. Finally, we conclude with a discussion about possible perspectives for the proposed method especially by focusing on other representation spaces or other classification methods.

The probability hypothesis density (PHD) methodology is widely used by the research community for the purposes of multiple object tracking. This problem consists in the recursive state estimation of several targets by using the information coming from an observation process. The purpose of this paper is to investigate the potential of the PHD filters for real-time traffic state estimation. This investigation is based on a Cell Transmission Model (CTM) coupled with the PHD filter. It brings a novel tool to the state estimation problem and allows to estimate the densities in traffic networks in the presence of measurement origin uncertainty, detection uncertainty and noises. In this work, we compare the PHD filter performance with a particle filter (PF), both taking into account the measurement origin uncertainty and show that they can provide high accuracy in a traffic setting and real-time computational costs. The PHD filtering framework opens new research avenues and has the abilities to solve challenging problems of vehicular networks.

International audience; The (24, 12, 8) extended binary Golay code is a well-known rate-1/2 short block-length linear error-correcting code with remarkable properties. This paper investigates the design of an efficient low-complexity soft-decision decoding architecture for this code. A dedicated algorithm is introduced that takes advantage of the code’s properties to simplify the decoding process. Simulation results show that the proposed algorithm achieves close to maximum-likelihood performance with low computational cost. The decoder architecture is described, and VLSI synthesis results are presented.

LGEP 2011 ID = 739; International audience; This paper shows that Ridge Polynomial Neural Networks (RPNN) and Least-Square Support Vector Machines (LS-SVM) technique provide efficient tools for microwave characterization of dielectric materials. Such methods avoids the slow learning properties of multilayer perceptrons (MLP) which utilize computationally intensive training algorithms and can get trapped in local minima. RPNN and LS-SVM are combined in this work with the Finite Element Method (FEM) to evaluate the dielectric materials properties. The RPNN is constructed from a number of increasing orders of Pi-Sigma units, it maintains fast learning properties and powerful mapping capabilities of single layer High Order Neural Networks (HONN). LS-SVM is a statistical learning method that has good generalization capability and learning performance. The FEM is used to create the data set required to train the RPNN and LS-SVM. The performance of a LS-SVM model depends on a careful setting of its associated hyper-parameters. In this study the LS-SVM hyper-parameters are optimized by using a Bayesian regularization technique. Results show that LS-SVM can achieve good accuracy and faster speed than neural network methods.

cote interne IRCAM: Helie08a; None / None; International audience; This paper proposes to solve and simulate various Kirchhoff models of nonlinear strings using Volterra series. Two nonlinearities are studied: the string tension is supposed to depend either on the global elongation of the string (first model), or on the local strain located at $x$ (second, and more precise, model). The boundary conditions are simple Dirichlet homogeneous ones or general dynamic conditions (allowing the string to be connected to any system; typically a bridge). For each model, a Volterra series is used to represent the displacement as a functional of excitation forces. The Volterra kernels are solved using a modal decomposition: the first kernel of the series yields the standard modes of the linearized problem while the next kernels introduce the nonlinear dynamics. As a last step, systematic identification of the kernels lead to a structure composed of linear filters, sums, and products which are well-suited to the sound synthesis, using standard signal processing techniques. The nonlinear dynamic introduced through this simulation is significant and perceptible in sound results for sufficiently large excitations.

International audience; This paper presents a simple approach to assess performance that can be achieved by the MMSE turbo equalizer in ST-BICM systems over multipaths Rayleigh block fading channels with i.i.d fading statistics. By considering perfect information exchange between the SISO decoder and the linear MMSE equalizer, the performance reaches the matched filter bound, and a closed form expression of the corresponding probability of bit error can be derived at the output of the equalizer. In particular, we emphasize that the suggested approach provides an attractive and reliable tool for performance validation consistently with the proposed expression of the probability of bit error. Simulations for 4-PSK and 8-PSK modulated signals show the relevance of the proposed approach and the full benefit provided by the MMSE turbo equalizer. In addition some clarification of the signal-to- noise ratio definition is pointed out.

International audience; Interleaving is a key component of many digital communication systems involving error correction schemes. It provides a form of time diversity to guard against bursts of errors. Recentlty, interleavers have become an even more integral part of the code design itself, if we consider for example turbo and turbo-like codes. In a non-cooperative context, such as passive listening, it is a challenging problem to estimate the interleaver parameters. In this paper, we propose an algorithm that allows us to estimate the parameters of the interleaver at the output of a binary symmetric channel and to locate the code-words in the interleaved block. This gives us some clues about the interleaving function used.

In object-oriented or object-relational databases such as multimedia databases or most XML databases, access patterns are not static, i.e., applications do not always access the same objects in the same order repeatedly. However, this has been the way these databases and associated optimisation techniques such as clustering have been evaluated up to now. This paper opens up research regarding this issue by proposing a dynamic object evaluation framework (DOEF). DOEF accomplishes access pattern change by defining configurable styles of change. It is a preliminary prototype that has been designed to be open and fully extensible. Though originally designed for the object-oriented model, it can also be used within the object-relational model with few adaptations. Furthermore, new access pattern change models can be added too. To illustrate the capabilities of DOEF, we conducted two different sets of experiments. In the first set of experiments, we used DOEF to compare the performances of four state of the art dynamic clustering algorithms. The results show that DOEF is effective at determining the adaptability of each dynamic clustering algorithm to changes in access pattern. They also led us to conclude that dynamic clustering algorithms can cope with moderate levels of access pattern change, but that performance rapidly degrades to be worse than no clustering when vigorous styles of access pattern change are applied. In the second set of experiments, we used DOEF to compare the performance of two different object stores: Platypus and SHORE. The use of DOEF exposed the poor swapping performance of Platypus., Comment: 20 pages

The quantification of the quality of a structural mechanical model remains a major issue today, with the use of an increasing number of methods in order to validate a model in comparison with an experimental reference. This paper presents a new theory based on the concept of Lack of Knowledge combining convex uncertainty models with probabilistic features by introducing for each substructure two bounds of the strain energy as stochastic variables. A general strategy of reduction of the lack of knowledge is discussed and applied to academic as well as industrial cases., SCOPUS: ar.j, info:eu-repo/semantics/published

This paper deals with an extension of dynamic subdomain methods. It relies on time multi-scale algorithms, in the particular case of explicit dynamics. It introduces new opportunities in terms of proper modeling on each subdomain adapted to its effective loading in order to reduce the calculation time of the simulations. Treatment of non-matching meshes and local modal projection methods are thus especially discussed. The efficiency of the method is then illustrated with two large-scale examples.

One characteristic of planar topological graphs is the reversal degree. In this paper, we propose an improve algorithm for calculating the reversal degree of a planar topological graphs. This algorithm explores various possible cases following the descending method. Practical tests carried out on machine, using graphs with more than fifty internal vertices of odd degree, have been realized within reasonable computing time., Le degré de retournement est une caractéristique des graphes planaires topologiques. Dans cet article nous proposons un algorithme amélioré pour calculer le degré de retournement d'un graphe planaire topologique. Cet algorithme explore les différents cas possibles suivant une méthode descendante. Son implémentation sur machine a donné lieu à des tests sur des cas pratiques, ceci en des temps de calcul tout à fait raisonnables, sur des graphes dont l'un comporte plus d'une cinquantaine de sommets intérieurs de degré impair

The Burmese have no patronymic. They have instead multiple personal names which, in combination, generally form two or three monosyllables. These names are either given by others or chosen by the individual and are selected using a widely-known system called mahābut. This paper examines how, according to the internal logic of this system, the name bears a dual aspect of fatality and free will. All calculations, including those related to astrology, begin with a number generated by taking the remainder of the year of birth divided by seven. By the association of the numbers produced by the various calculations with a chart of syllables, it is possible to assemble a name. The remainder (from which the name is generated) introduces a notion of randomness or freedom which minimizes the belief in karmic predestination., Robinne François. La notion de reste dans le choix du nom personnel en Birmanie (Myanmar). In: Aséanie 1, 1998. pp. 91-105.

A model of pitch perception is presented involving an array of delay lines and inhibitory gating neurons. In response to a periodic sound, a minimum appears in the pattern of outputs of the inhibitory neurons at a lag equal to the period of the sound. The position of this minimum is the cue to pitch. The model is similar to the autocorrelation model of pitch, multiplication being replaced by an operation similar to subtraction, and maxima by minima. The two models account for a wide class of pitch phenomena in very much the same way. The principal goal of this paper is to demonstrate this fact. Several features of the cancellation model may be to its advantage: it is closely related to the operation of harmonic cancellation that can account for segregation of concurrent harmonic stimuli, it can be generalized to explain the perception of multiple pitches, and it shows a greater degree of sensitivity to phase than autocorrelation, which may allow it to explain certain phenomena that autocorrelation cannot account for.

In spectral analysis and pattern recognition, especially in speech processing, AutoRegressive (AR) modeling is widely used as a signal parameter estimation tool. In this paper, AR estimation behaviour is studied when applied to signals presenting abrupt changes at an unknown instant of time. A particular abrupt change is studied: the additive change case. This change occurs when, at the instant of change, a signal adds to one which was present before - both signals are independent -. The theoretical sliding window AR parameter expressions are given. We show that blind sliding window AR estimation can lead to a detection tool, allowing additive changes to be detected and distinguished

In this paper, we proposed a approach to the two-microphone speech enhancement problem based on the Blind Separation of Sources for convolutive mixtures. The separation of signals can be achieved by a recursive structure of adaptive Filters FIR. The Filter coefficients must be updated by using Higher Order Statistics in order to insure the output independence. Various adaptive algorithms based on different independence criteria are proposed to estimate the filters. The experimental results have been obtained for different types of signals in various situations of mixtures. For instance, using two microphones, the algorithms are able to separate two speech signals without any knowledge of the signals

The work presented in this paper deals with the decomposition of pseudoperiodic signals in periodic components by using a spectral interpolation method. This method is applied to the autocorrelation of a pseudoperiodic signal instead of the signal itself. Results obtained by the present method are not very sensitive to the noise effect and are generally more accurate than those directly obtained by using the spectral interpolation method on the signal

Copyright © International Union of Crystallography; After a brief review of the crystallographic Fourier transform problem, this paper compares three methods for its computer implementation with reference to core-storage capacity and computation time: the classic method, the simple Fast Fourier Transform algorithms and a new method. The first method needs, especially for a macromolecular three-dimensional structure, too many operations and therefore too long a computation time and poor accuracy. The remarkable FFT algorithm, on the other hand, leads to large savings in computation time with a better accuracy, but using no crystallographic symmetry wastes too much storage capacity. The third method, using FFT but taking into account Friedel's law by means of a simple in situ process, approximately halves the storage capacity as well as the computation time.

Le medium algorithmique est une infrastructure de communication qui augmente les pouvoirs des médias antérieurs en y ajoutant la mécanisation des opérations symboliques. Son émergence au milieu du vingtième siècle résulte d’une longue histoire scientifique et technique que je résume au début de l’article. Je rappelle ensuite les grandes étapes de son développement (ordinateurs centraux, internet et PC, Web social, Cloud augmenté par l’intelligence artificielle et la chaîne de blocs) ainsi que leurs conséquences sociocognitives. J’évoque pour finir les développements futurs de ce médium dans la perspective d’une intelligence collective réflexive basée sur une nouvelle forme de calcul sémantique., The algorithmic medium is an infrastructure of communication augmenting the powers of previous media by adding the automation of symbolic operations. Its emergence in the middle of the twentieth century results from a long scientific and technological history that I summarize at the beginning of the paper. Then I recall in this article the main stages of its development (mainframes, Internet and PC, social Web, cloud augmented by artificial intelligence and the blockchain) as well as their socio-cognitive consequences. I evoke in the end the future developments of this medium, in the perspective of a reflexive collective intelligence based on a new form of semantic computation.

CANDIDE-R is a huge simultaneous macro-economic model which raises estimations difficulties. We avoid the problem of identification assuming that the great number of variables in our model makes it impossible that the necessary condition be not satisfied. We assume that our system converges to a solution solving this way the problem of identification. The core of the paper gives justifications of the procedure we adopted to estimate CANDIDE-R. Because of the presence of regional equations and the limited amount of regional data, we are bound to pool cross sections and time series data. We then justified the use of Zellner's approach instead of the error components models within the class of regional models built on national premises.