Search results for "Signal"
showing 10 items of 6924 documents
Ontology-driven Image Analysis for Histopathological Images
2010
International audience; Ontology-based software and image processing engine must cooperate in new fields of computer vision like microscopy acquisition wherein the amount of data, concepts and processing to be handled must be properly controlled. Within our own platform, we need to extract biological objects of interest in huge size and high-content microscopy images. In addition to specific low-level image analysis procedures, we used knowledge formalization tools and high-level reasoning ability of ontology-based software. This methodology made it possible to improve the expressiveness of the clinical models, the usability of the platform for the pathologist and the sensitivity or sensibi…
Kolmogorov Superposition Theorem and Its Application to Multivariate Function Decompositions and Image Representation
2008
International audience; In this paper, we present the problem of multivariate function decompositions into sums and compositions of monovariate functions. We recall that such a decomposition exists in the Kolmogorov's superposition theorem, and we present two of the most recent constructive algorithms of these monovariate functions. We first present the algorithm proposed by Sprecher, then the algorithm proposed by Igelnik, and we present several results of decomposition for gray level images. Our goal is to adapt and apply the superposition theorem to image processing, i.e. to decompose an image into simpler functions using Kolmogorov superpositions. We synthetise our observations, before …
The Kolmogorov superposition theorem and its application to image processing
2010
Best student paper award; International audience
Noise removal using a nonlinear two-dimensional diffusion network
1998
Un reseau electrique non lineaire bidimensionnel, constitue de N×N cellules identiques, et modelisant l’equation de Nagumo discrete est presente. A l’aide d’une nouvelle description de la fonction non lineaire, on peut predire analytiquement l’evolution temporelle de la partie coherente du signal, ainsi que celle des perturbations de petites amplitudes qui lui sont superposees. Enfin, des applications a l’amelioration du rapport signal sur bruit, ou au traitement d’images sont suggerees.
COLORED NOISE EFFECTS ON GHOST STOCHASTIC RESONANCE
2014
International audience; We analyze the Ghost Stochastic Resonance (GSR) effect in an electronic circuit exactly ruled by the FitzHugh-Nagumo (FHN) equations, both numerically and experimentally. When the circuit is excited with a bichromatic driving with two close frequencies, we show that for an appropriate noise intensity the circuit response exhibits a ghost frequency which is not present in the biharmonic input signal. In this paper, we highlight the e ects of colored noise on GSR.
Analyse de la dynamique de la durée du potentiel d'action cardiaque à travers un modèle itératif
2013
International audience; Le présent travail a pour but de caractériser, par une étude mathématique rigoureuse la dynamique du modèle itératif de la durée du potentiel d'action. L'étude de ce modèle, qui découle de celui de Beeler Reuter (BR), se caractérise par une dynamique matérialisée par une courbe de restitution et qui peut servir d'outil pertinent dans l'analyse et le diagnostic d'arythmie. Par ailleurs l'analyse de la stabilité du modèle permet de définir les zones d'existence de différents rythmes cardiaques.
Étude de la Dynamique des Ondes Spirales à l'Échelle Cellulaire par Modèles Expérimental et Numérique
2012
Among the death due to the cardiac problems, the arrhythmias play a major role, particularly the atrial disorders. This alarming situation attracts an intense research, but it is still limited by the availability of experimental models to reproduce the triggering mechanisms of arrhythmias at the cellular level and extensions of these anomalies. Whether they occur on a healthy or pathological heart, or they are benign or potentially dangerous (risk of sudden death), the arrhythmias constitute an important chapter of the cardiology. This thesis is interested in the studying and modeling of the arrhythmias at a cellular scale. Thus the problems of this thesis can be summarized briefly by the f…
Noise estimation from digital step-model signal
2013
International audience; This paper addresses the noise estimation in the digital domain and proposes a noise estimator based on the step signal model. It is efficient for any distribution of noise because it does not rely only on the smallest amplitudes in the signal or image. The proposed approach uses polarized/directional derivatives and a nonlinear combination of these derivatives to estimate the noise distribution (e.g., Gaussian, Poisson, speckle, etc.). The moments of this measured distribution can be computed and are also calculated theoretically on the basis of noise distribution models. The 1D performances are detailed, and as our work is mostly dedicated to image processing, a 2D…
Entire Reflective Object Surface Structure Understanding
2015
International audience
SiPM cryogenic operation down to 77 K
2013
International audience; Silicon PhotoMultiplier (SiPM) is composed of extremely sensitive photosensors based on the Geiger Mode Avalanche PhotoDiode (GM-APD), which operate as a digital pixel sensitive to single photons. SiPMs are being considered for applications in low temperature environments, such as noble-liquid detectors for dark matter searches or neutrino physics and GM-APD is promising technology for space Compton telescopes. While it is well known that the dark count rate, one of the main limitations of SiPM, is reduced at low temperature, a detailed study of the behavior of the device in cryogenic environment is necessary to assess its performances. In this paper, we present meas…