Search results for "Item"
showing 10 items of 363 documents
Test fairness: a DIF analysis of an L2 vocabulary test
2000
The purpose of this study is to analyse gender-uniform differential item functioning (DIF) in a second language (L2) vocabulary test with the tools of item response theory (the separate calibration t-method) and to study potential gender impact on the test performance measured by different item composites. The results of the study show that despite the fact that there are test items with indications of DIF in favour of either females or males, the test as a whole is not gender-biased. In spite of this, it was demonstrated that some item composites are gender-biased. In view of item bank building and use, it means that some of the tests constructed on the basis of an item bank might be bias…
Dispositif virtuel d'aide à la chirurgie de l'épaule
2008
The goal of this research is to design a virtual reality prototype to assit an orthopedic surgeon during the replacement of the glenohumeral joint by prosthesis. This system aims to optimize the movements of prosthesized shoulder joint from a choice of various scenarios of pose. These works encompasses several topics such as : orthopedic surgery, image analysis, computer graphics and virtual reality. The chosen process includes a phase of modelling of the bony part of the articulation by simple geometric forms, this model is parameterized from radios or CT scans ; a phase of simulation of the movements of healthy glenohumeral joint ; nally the phase of simulation of cutting and drilling wit…
Procédé de codage d'un signal réel en un signal quantifié
2017
Procédé, mis en œuvre par un processeur, de codage d'un signal réel, par exemple un signal image, en un signal quantifié, ledit procédé comprenant les étapes suivantes appliquées à chaque échantillon réel dudit signal réel : • Convertir (101) l'échantillon réel dans une représentation numérique, • Sélectionner (102), dans la partie fractionnaire du nombre, un nombre N prédéterminé de bits non nuls les plus significatifs, • pour chaque bit i significatif non nul sélectionné, i variant de 1 à N, déterminer (103) sa distance P, par rapport au bit significatif non nul sélectionné voisin de rang supérieur ou, pour le premier bit significatif non nul sélectionné, par rapport à la virgule, • retra…
Système de sécurité biométrique multimodal par imagerie, dédié au contrôle d’accès
2019
Research of this thesis consists in setting up efficient and light solutions to answer the problems of securing sensitive products. Motivated by a collaboration with various stakeholders within the Nuc-Track project, the development of a biometric security system, possibly multimodal, will lead to a study on various biometric features such as the face, fingerprints and the vascular network. This thesis will focus on an algorithm and architecture matching, with the aim of minimizing the storage size of the learning models while guaranteeing optimal performances. This will allow it to be stored on a personal support, thus respecting privacy standards.
Une architecture programmable de traitement des impulsions zéro-temps mort pour l'instrumentation nucléaire
2015
In the field of nuclear instrumentation, digital signal processing architectures have to deal with the poissonian characteristic of the signal, composed of random arrival pulses which requires current architectures to work in dataflow. Thus, the real-time needs implies losing pulses when the pulse rate is too high. Current architectures paralyze the acquisition of the signal during the pulse processing inducing a time during no signal can be processed, this is called the dead time. These issue have led current architectures to use dedicated solutions based on reconfigurable components such as FPGAs. The requirement of end users to implement a wide range of applications on a large number of …
Estimation des Cartes du Temps de Collision (TTC) en Vision Para-catadioptrique
2013
National audience; Le temps de contact ou le temps de collision (TTC) est une information importante pour la navigation et l'évitement d'obtacles. Son estimation a largement été étudiée dans le cas des caméras perspectives. Par contre, très peu de travaux ont été effectués sur ce sujet pour les caméras catadioptriques, alors qu'elles sont très utiles, notamment, en navigation des robots mobiles. L'objectif de cet article, est de proposer un nouveau modèle d'estimation du TTC pour les caméras paracatadioptriques basé sur le flot optique, en adaptant celui développé pour les caméras perspectives. Le calcul du TTC en chaque pixel permet d'obtenir la carte des temps de collision. Nous avons val…
Conception d'un outil de prototypage rapide sur le FPGA pour des applications de traitement d'images
2011
This manuscript presents work to propose a development cycle to establish RISP processors in a reprogrammable chip (FPGA). After a description of the various possible solutions to produce image processing prototypes, this document describes a method which consists in generating hardware models of processor target to image processing, with operators just for a given application. Test with a set of common algorithm makes evaluate the performances of the design cycle proposed. Rapid prototyping of a contact less biometric system, based on palmprint recognition, is also realized on the test platform.
Nouvelles méthodes de traitement de signaux multidimensionnels par décomposition suivant le théorème de Superposition de Kolmogorov
2010
The processing of multidimensional signal remains difficult when using monodimensional-based methods. Therefore, it is either required to extend monodimensional methods to several dimensions, which is not always possible, or to convert the multidimensional signals into 1D signals. In this case, the priority is to preserve most of the properties of the original signal. In this context, the Kolmogorov Superposition Theorem offers a promising theoretical framework for multidimensional signal conversion. In 1957, Kolmogorov demonstrated that any multivariate function can be written as sums and compositions of monovariate functions.We have focused on the image decomposition according to the supe…
Adéquation Algorithme architecture : Aspects logiciels, matériels et cognitifs
2008
Les travaux présentés dans le cadre de cette Habilitation à Diriger des Recherches s'inscrivent principalement dans la problématique dite d'" Adéquation Algorithme Architecture ". Ils ont pour objectif commun la mise en œuvre de systèmes matériels et logiciels dédiés à la vision artificielle à fortes contraintes temporelles. Ils se focalisent sur différents aspects cruciaux tels que l'acquisition d'images par des capteurs dédiés, le développement et la programmation d'architectures optimisées de traitement des images et l'implantation d'algorithmes de traitement du signal et d'images en temps réel sur ces architectures.
Retrievals of soil moisture and optical depth from CAROLS
2011
International audience; We propose in this paper to evaluate a method to retrieve soil moisture (SM) and vegetation optical thickness, in areas of unknown roughness and unknown vegetation water content in view of operational applications, by using airborne Tb measurements acquired in South-West of France. Results are compared to in situ measurements, manual and automatic ones included in SMOSmania network, in the South-West of France.