Search results for "BRUIT"
showing 10 items of 15 documents
Modulational instability in fiber systems with periodic loss compensation and dispersion management
2003
In this paper we study modulational instability in a Kerr fiber taking into account the combined effects of periodic power variations and dispersion management. It is shown that periodic dispersion management and periodic amplification produce nonconventional MI sidebands which are essentially independent of each other. In addition, we show that the amplifier spontaneous emission noise tends to inhibit the growth of sidebands, for a sufficiently long propagation distance.
Noise contribution to resonance phenomena and information propagation in non linear electronic networks
2015
This manuscript presents research aiming to show possible positive effects of deterministic and stochastic perturbations on the responses of different nonlinear systems. To that end, both numerical and experimental studies were carried out on two kinds of structures : an elementary electronic FitzHugh-Nagumo oscillator and an electrical line developed by resistively coupling 45 elementary cells. In the first section, the elementary cell characterization was undertaken in a deterministic regime. In the presence of a bichromatic stimulus, it is shown that when the low frequency component is subthreshold, its detection can be maximized for an optimal magnitude of the second component thanks to…
Error sources on the land surface temperature retrieved from thermal infrared single channel remote sensing data
2006
In this paper, a theoretical study complementary to others given in the literature about the errors committed on the land surface temperature retrieved from the radiative transfer equation in the thermal infrared region by remote sensing techniques has been analysed. For this purpose, the MODTRAN 3.5 code has been used in order to simulate different conditions and evaluate the influence of several parameters on the land surface temperature accuracy: atmospheric correction, noise of the sensor, land surface emissivity, aerosols and other gaseous absorbers, angular effects, wavelength uncertainty, full‐width half‐maximum of the sensor and band‐pass effects. The results show that the most impo…
Electronic implementation of a non-linear oscillator subjected to noise : application to the modeling of neuronal information coding
2011
We study the nonlinear FitzHugh-Nagumo model witch describes the dynamics of excitable neural element. It is well known that this system exhibits three different possible responses. Indeed, the system can be mono-stable, oscillatory or bistable. In the oscillatory regime, the system periodically responds by generating action potential. By contrast, in the mono-stable state the system response remains constant after a transient. Under certain conditions, the system can undergo a bifurcation between the stable and the oscillatory regime via the so called Andronov-Hopf bifurcation. In this Phd thesis, we consider the FitzHugh-Nagumo model in the stable state, that is set near the Andronov-Hopf…
Comparison of cloud-reconstruction methods for time series of composite NDVI data
2010
Land cover change can be assessed from ground measurements or remotely sensed data. As regards remotely sensed data, such as NDVI (Normalized Difference Vegetation Index) parameter, the presence of atmospherically contaminated data in the time series introduces some noise that may blur the change analysis. Several methods have already been developed to reconstruct NDVI time series, although most methods have been dedicated to reconstruction of acquired time series, while publicly available databases are usually composited over time. This paper presents the IDR (iterative Interpolation for Data Reconstruction) method, a new method designed to approximate the upper envelope of the NDVI time s…
Stéréophonie et littérature : résonnance et reverbération dans les chansons de gestes et romans des XIIe et XIIIe siècles
2016
The chansons de geste and chivalric romances from the 12th and 13th centuries are a faithful testimony of the reality of their time, and sensory perceptions are among these testimonies. The written word provides not only descriptive and objective information, but also the impressions perceived and conveyed by the author, which are the sensations the reader has to get acquainted with in order to make the story their own. Mentions to sound effects and the sound features of a particular space are remarkable, and a compilation of these references from various texts allows us to study the sounds, resonances, and spaces through which the sound event gains prominence in the narrative. These includ…
Multispectral imaging and its use for face recognition : sensory data enhancement
2015
In this thesis, we focus on multispectral image for face recognition. With such application,the quality of the image is an important factor that affects the accuracy of therecognition. However, the sensory data are in general corrupted by noise. Thus, wepropose several denoising algorithms that are able to ensure a good tradeoff betweennoise removal and details preservation. Furthermore, characterizing regions and detailsof the face can improve recognition. We focus also in this thesis on multispectral imagesegmentation particularly clustering techniques and cluster analysis. The effectiveness ofthe proposed algorithms is illustrated by comparing them with state-of-the-art methodsusing both…
Noise identification and sampling frequency determination for precise Pb isotopic measurements by quadrupole-based Inductively Coupled Plasma Mass Sp…
2000
Analytical precision of the isotope ratios measured by quadrupole-based ICP-MS is drastically controlled by the low- frequency noises which originate from nebulisation and vaporisation processes, and from sample introduction systems. The unde- sirable influence of these latter can be however reduced by choosing efficiently the operating parameters. In the present study , the choice of the stabilisation time necessary in peak jump mode, and the one of the number of sweeps are discussed in the light of noise power spectra obtained with various speeds of the peristaltic pump used as sample introduction system. Obviously, the settings proposed are probably efficient only on our own ICP-MS, but …
Estimation des dimensions en présence d'erreurs
2018
Journées du GDR Analyse Multifractale, Nouan-le-Fuzelier, FRANCE, 16-/09/2018 - 20/09/2018; Nous nous posons la question de l'estimation des différentes dimensions fractales lorsque nous sommes en présence de bruit additif (à une itération donnée) ou multiplicatif ( qui se propage à travers les itérations), en testant, sur des fractales construites, les méthodes classiques d'estimation et en analysant la structure des résidus d'estimation.
Comparison and multiresolution analysis of irregular meshes with appearance attributes
2004
We present in this dissertation a method to compare and to analyse irregular meshes with appearance attributes. First, we propose a mesh comparison method using a new attribute deviation metric. Considered meshes contain geometric and appearance attributes (e.g. color, texture,temperature). The proposed deviation assessment allows the computation of local attribute differences between two meshes. We present an application of this method to mesh simplification algorithm quality assessment.Then we propose two multiresolution analysis schemes for irregular meshes with appearance attributes. First, a mesh is decomposed in a discret number of levels of detail. We introduce a surface geometry rel…