Dissertations / Theses on the topic 'Haute résolution spectrale'
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Caspary, Olivier. "Applicabilité des méthodes d'analyse spectrale à haute résolution fréquentielle." Nancy 1, 1995. http://www.theses.fr/1995NAN10004.
Rouquette, Stéphanie. "Analyse spectrale haute résolution de signaux bidimensionnels : application à l'imagerie radar." Bordeaux 1, 1998. http://www.theses.fr/1998BOR10655.
Bourguignon, Sébastien. "Analyse spectrale à haute résolution de signaux irrégulièrement échantillonnés : application à l'Astrophysique." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00116827.
Une première approche envisagée a trait au domaine de l'optimisation et consiste à minimiser un critère de type moindres carrés, pénalisé par une fonction favorisant les solutions parcimonieuses. La pénalisation par la norme l1 est en particulier étudiée en extension à des variables complexes et s'avère satisfaisante en termes de modélisation. Nous proposons des solutions algorithmiques particulièrement performantes permettant d'envisager une analyse à très haute résolution fréquentielle.
Nous étudions ensuite la modélisation probabiliste des amplitudes spectrales sous la forme d'un processus Bernoulli-Gaussien, dont les paramètres sont estimés au sens de la moyenne a posteriori à partir de techniques d'échantillonnage stochastique, permettant d'envisager une estimation totalement non supervisée. L'interprétation probabiliste du résultat ainsi que l'obtention conjointe des variances associées, sont alors d'un intérêt astrophysique majeur, s'interprétant en termes de niveaux de confiance sur les composantes spectrales détectées. Nous proposons dans un premier temps des améliorations de l'algorithme échantillonneur de Gibbs permettant d'accélérer l'exploration de la loi échantillonnée. Ensuite, nous introduisons des variables de décalage fréquentiel à valeur continue, permettant d'augmenter la précision de l'estimation sans trop pénaliser le coût calculatoire associé.
Pour chaque méthode proposée, nous illustrons sur des simulations la qualité de l'estimation ainsi que les performances des algorithmes développés. Leur application à un jeu de données issu d'observations astrophysiques est enfin présentée, mettant en évidence l'apport d'une telle méthodologie par rapport aux méthodes d'analyse spectrale habituellement utilisées.
Ferrari, André. "Contribution à l'étude et au développement de méthodes haute résolution en analyse spectrale." Nice, 1992. http://www.theses.fr/1992NICE4600.
The spectral estimation of a signal composed by complex sinusoids and corrupted by a Gaussian noise is the main topic of this dissertation. Initially, a statistical approach of the problem is considered. The noise is first assumed white. Algorithms based on the spectral decomposition of the process autocorrelation matrix or on noise substraction are proposed. The particular case of a periodic signal is discussed. In a second time, the noise is assumed colored. Solutions based on the fourth order cumulants of the signal are presented. The problem is also studied in a deterministic way. A general approach based on the compensation of a data matrix under different structural constraints is developped. Finally, the performances of the different algorithms are derived performing simulations on synthetic signals
Bourguignon, Sébastien. "Analyse spectrale à haute résolution de signaux à échantillonnage irrégulier : application à l'astrophysique." Toulouse 3, 2005. http://www.theses.fr/2005TOU30190.
Zagolski, Francis. "Evaluation des concentrations chimiques d'un couvert forestier à l'aide de la haute résolution spectrale." Toulouse 3, 1994. http://www.theses.fr/1994TOU30082.
Olivier, Francis. "Méthodes d'analyse spectrale à haute résolution appliquées à l'imagerie acoustique de sources d'ondes planes." Aix-Marseille 2, 1987. http://www.theses.fr/1987AIX22088.
Lafitte-Houssat, Eloïse. "Cristaux dopés ytterbium pour les technologies quantiques et l'analyse spectrale à très haute résolution." Electronic Thesis or Diss., Université Paris sciences et lettres, 2022. http://www.theses.fr/2022UPSLC003.
Crystals doped with paramagnetic rare earth ions are promising materials for quantum information processing because they can provide large bandwidth optical memories and spectral analyzers at low temperature. Furthermore, it was recently demonstrated that coherence transfer was possible between optical and spin transitions in these materials, opening the way to long storage time capability. The ability to tailor the absorption profile of these ions also gives way to radio frequency analysis with a broad bandwidth and fast dynamics, and possible new architecture for signal processing. Yb3+ has very remarkable optical properties in Y2SiO5, especially in terms of oscillator strength and narrow inhomogeneous linewidths at low concentrations. This PhD work focuses on the 171Yb3+ isotope, which is the only paramagnetic rare earth ion with a nuclear spin I=1/2, leading to a simple energy level structure. Thanks to the narrow inhomogeneous linewidths (≈1 GHz), the nuclear spin transitions are optically resolved, which leads to efficient optical pumping of spin levels and can facilitate state preparation for quantum processing applications.The system 171Yb3+:Y2SiO5 shows great coherence properties, however limited at low temperature by cross-relaxation between neighboring spins. Instead of using a magnetic field to reduce these spin-flips, we chose to stay at zero magnetic field, to make use of the low-decoherence ZEFOZ point of our system, and used a material-focused approach to solve this cross relaxation limit. To do so, single crystals were grown during the PhD by the Czochralski method, with fully tunable growth conditions. High crystalline quality enhances optical and spin coherences for long storage time quantum memories or high-resolution high-bandwidth analysis of optically carried radio frequency signals. In this work, different parameters were investigated in order to identify the conditions offering the best properties for the desired applications: doping concentration, growth atmosphere, transition, orientation of the crystal, and temperature. A thorough study of the material could then be led as a function of these experimental conditions. Despite the higher sensibility of paramagnetic rare earth ions to magnetic field fluctuations, the longest optical coherence time at zero magnetic field for a paramagnetic ion could be obtained in a 2 ppm doped 171Yb3+:Y2SiO5 crystal grown under oxygen atmosphere, reaching more than a millisecond. A way to efficiently couple 171Yb3+ to integrated photonic devices was finally studied. A doped LiNbO3 single crystal was thus explored for the first time, showing promising properties. The values established here will serve as a reference for future work in this material, in which fabrication of nanoscale optical structures like waveguides or optical resonators is already a mature technology
François, Patrick. "Nucléosynthèse des métaux légers : observations à haute résolution spectrale et comparaison aux modèles d'évolution galactique." Observatoire de Paris, 1986. https://hal.archives-ouvertes.fr/tel-02095285.
Mahmoud, Ali. "Analyseur de spectre à haute résolution : Apllication à la mesure des oscillateurs ultrastables." Besançon, 1989. http://www.theses.fr/1989BESA2004.
Badeau, Roland. "Analyse spectrale à haute résolution et décompositions non-négatives appliquées au traitement des signaux de musique." Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00945245.
Dubos, Sébastien. "Nouveau spectro-imageur CdTe à très haute résolution spatiale et spectrale pour l'astronomie X et gamma." Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCC159.
The thesis work presented in the manuscript corresponds to the first development phase of the MC2 project, an ambitious R & D effort to realize a new type of CdTe-based imaging spectrometer for future hard X- and gamma-rays astronomy missions. The objective is to achieve a 300 micron-pitch pixelated detector plane hybrided with a very low noise front-end electronics for a total pixel density multiplied by 4 compared to the most advanced system recently available in the laboratory (Caliste HD module). Moreover, thanks to the joint development of reading circuits adapted to the interconnection of pixelated detectors with low capacitance and low leakage current, spectroscopic performances of such system are assumed to approach inherent limitations of the CdTe detector, specifically for the lowest energies. My work was organized in parallel and complementary areas: evaluation of current systems, feedback and identification of issues associated with the development of highly-resolved detection planes, implementation and complete characterization of a new two-dimensional ASIC specifically developed for this application, and modelling and study of the associated sensor to optimize the design of the detector pattern. Finally, a first hybrid prototype was completed and first experimental tests thereby conducted
Lumeau, Bernard. "Traitement spatial et analyse spectrale applications neurophysiologiques /." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37607489r.
Chambord, Sylvain. "Haute résolution spectrale dans l'ultra-violet lointain : simulation et évaluation expérimentale d'un spectrographe protoype pour l'instrument spatial "FUSE"." Aix-Marseille 3, 1995. http://www.theses.fr/1995AIX30033.
Gaudfrin, Florian. "Lidar supercontinuum pour la caractérisation spectrale des milieux diffusants à haute résolution spatiale : Étude numérique et développement instrumental." Thesis, Toulouse, ISAE, 2020. http://www.theses.fr/2020ESAE0007.
Lidar diagnostic methods provide information on the optical parameters of the medium (scattering and absorption coefficients). These quantities depend on the properties of light (wavelength, polarization) and are then used to retrieve the microscopic properties of the medium such as size distribution, morphology, optical index or particle concentration. However, current lidar techniques have limitations. The laser sources used are limited to a few visible or near infrared wavelengths and the identification of the microphysical properties requires a priori knowledge of the scattering medium. Hypotheses are formulated to constrain the inversion methods and to provide information of interest on natural and anthropogenic aerosols (carbonaceous particles, desert dust, volcanic ash, etc.). In addition, current lidars consider kilometric ranges, whereas there are applications for those at short distances: in situ measurements at nozzle outlets, local control of industrial plumes with high spatial resolution, etc. Supercontinuum laser sources extend from the visible to the infrared and offer new possibilities for measuring the optical properties of aerosols over a wide continuous spectral range. Their use in lidar systems is considered to identify the optical properties of the medium over a wide and continuous range of wavelengths. A major objective of this thesis is to demonstrate the viability of supercontinuum lidars for the spectral characterization of surface and volume targets at high spatial resolution. The first axis concerns the numerical study of the system with the development of the PERFALIS simulator. The second axis focuses on the instrumental design of a lidar called COLIBRIS, allowing short-range lidar measurements with high spatial resolution (submetric). A first version was proposed in monochromatic analysis and a second one with a hyperspectral analysis of backscattered light. Finally, a new lidar inversion method named ST-LIM has been developed to identify the optical properties of a plume without any a priori hypothesis on the lidar ratio (optical parameter characterizing the surveyed medium). The comparison of experimental measurements with simulation results validates the lidar simulator in its two operating modes (monochromatic and hyperspectral). The results show the importance of considering the actual shape of the laser pulses during the light-matter interaction in the case of thin plume soundings with high spatial resolution. In the future, the lidar simulator may be used to design new supercontinuum or monochromatic lidar instruments and to study their performance for on-board versions
Montandon, Véronique. "Un modèle neuronal pour la simulation opérationnelle des radiances observées par l'interféromètre spatial à haute résolution spectrale IASI." Paris 6, 2002. http://www.theses.fr/2002PA066442.
Crevoisier, Cyril. "Etude de la distribution du CO2 atmosphérique à partir des observations infrarouges à haute résolution spectrale de l'instrument AQUA/AIRS." Paris 7, 2004. http://www.theses.fr/2004PA077041.
Adnet, Claude. "Unification des méthodes d'analyse spectrale (Fourier et haute résolution) en vue de la réalisation d'un système expert d'aide à l'analyse." Grenoble INPG, 1990. http://www.theses.fr/1990INPG0110.
Poulalion, Guy. "Détection et estimation conjointes en analyse spectrale haute résolution : application à l'analyse de signaux issus de mesures de surface équivalente radar." Bordeaux 1, 1997. http://www.theses.fr/1997BOR10647.
Vibert-Charbonnel, Pascal. "Méthodes de traitement des mesures magnétiques en forage pour la datation haute-résolution des séries sédimentaires." Grenoble INPG, 1996. http://www.theses.fr/1996INPG0183.
Eremenko, Maxim. "Inversion des spectres infrarouges à haute résolution spectrale enregistrés en absorption à partir de ballons stratosphériques : ajustement global de grands domaines spectraux : inversion multi-paramètres (espèces moléculaires)." Paris 6, 2003. http://www.theses.fr/2003PA066109.
Servadio, Zarah. "Apports de l'imagerie à haute résolution spectrale et spatiale dans les bilans de volume et bilans radiatifs au Piton de La Fournaise." Phd thesis, Université de la Réunion, 2011. http://tel.archives-ouvertes.fr/tel-00858749.
Servadio, Zarah. "Apports de l’imagerie à haute résolution spectrale et spatiale dans les bilans de volume et bilans radiatifs au Piton de La Fournaise." Thesis, La Réunion, 2011. http://www.theses.fr/2011LARE0020/document.
Remote sensing opens new perspectives for the study and monotoring of volcanoes. In this thesis, different approaches were discussed. optical and thermal satellite imagery provides a synoptic view over a wide area. The understanding of surface state changes is particulary important in the monotoring of the activity of active volcanoes. Several, questions arise: • What advantages offer optical observation satellites of the Earth for calculations of lava volumes issues? • What are their limits? • Calculations of flow by remote sensing are reliable? • What is the interest of a multi-tool and multi-source approach? These issues were addressed by taking the Piton de la Fournaise to target. Several methods have been implemented and tested: 1) automatic extraction of the contours of flows of lava, 2) the cretion of numerical model of elevation (DEM) imaging satellite, 3) the calculation of flows from thermal images, 4) follow-up post eruptive flow modelling of cooling and the observed deformations in-situ measurement. The added value of this work is the ability to validate the results of remote sensing measurements from models because of the proximity of the sites studied in situ. The use of these techniques to obtain the average flow rates of lavas to several eruptions and follow topographic evolution of the volcano and its large structures. Satellite thermal measurements provide the means of forcing changes in the flow of eruptions over time, while Dems helped to obtain a total volume in the case of flows with high thicknesses. With these techniques, it was possible to define two types of erutions with changes similar to those observed on different volcanoes
CIUCIU, Philippe. "MÉTHODES MARKOVIENNES EN ESTIMATION SPECTRALE NON PARAMETRIQUES. APPLICATION EN IMAGERIE RADAR DOPPLER." Phd thesis, Université Paris Sud - Paris XI, 2000. http://tel.archives-ouvertes.fr/tel-00003664.
Sow, Papa lat tabara. "Développement d'un spectromètre laser à cascade quantique pour des applications en spectroscopie de haute résolution et en métrologie des fréquences." Thesis, Sorbonne Paris Cité, 2015. http://www.theses.fr/2015USPCD011/document.
This thesis is devoted to the developpement of a laser spectrometer quantum cascade to frequency metrology and high-resolution spectroscopy. The objective of this work is to developp a new tool for projects in our group : Measuring the Boltzman constant and test of non conservation of parity. Thus the new source was characterized by measuring its spectral density noise, amplitude noise and its emission line width. The phase locking of the QCL on the CO2 laser has achived spectroscopy NH and MTO, molecules of interest for the projects of the group mentioned aboive respectively
Ouamri, Abdelaziz. "Étude des performances des méthodes d'identification à haute résolution et application à l'identification des échos par une antenne linéaire multicapteurs." Paris 11, 1986. http://www.theses.fr/1986PA112172.
This thesis deals with performances of high resolution identification methods applied to correlated or non-correlated sources, using a linear array antenna. We show that in the case of totally correlated sources (multiple paths) the covariance matrix must be computed using a "sliding average" (spatial averaging). The finite size of the sample induces a statistical error on the estimation of the covariance matrix. We henceforth have to study the perturbations of the eigenvectors and eigenvalues of this matrix. The study of eigenvalues led us to introduce a criterium allowing the determination of the number of sources. The study of eigenvectors enabled us to find a relationship between these perturbations and the corresponding ones on the sources. We could thus compare to optimality the methods of both Tufts-Kumaresan, and the goniometer. The optimal case was established thanks to a new approach. We thus obtained general formulas giving the minimum variance (Cramer-Rao bounds). We compared to this optimal quantity the variance obtained by each method. Without sliding average, we show that the goniometer method is quasi¬ optimal, while the Tufts-Kumaresan method give poorer results. We also introduce a new quasi maximum likelihood method which is quasi-optimal either with correlated or non-correlated sources. If sliding average is used, the Tufts-Kumaresan method is near optimal even in the case of totally correlated sources. As an original result, we established a method for estimating the covariance matrix in a Toeplitz form without bringing any bias on the estimation of the sources. All these identification methods were tested on experimental data in an anechoïd chamber (multiple paths simulation)
Badeau, Roland. "Méthodes à haute résolution pour l'estimation et le suivi de sinusoïdes modulées : Application aux signaux de musique." Phd thesis, Télécom ParisTech, 2005. http://tel.archives-ouvertes.fr/tel-00009321.
Fourty, Thierry. "Estimation du contenu biochimique d'un couvert végétal à partir de données haute résolution spectrale acquises au niveau satellitaire : [thèse soutenue sur un ensemble de travaux]." Toulouse 3, 1996. http://www.theses.fr/1996TOU30213.
Ros, Jean-Marc. "Contribution au développement des méthodes d'analyse spectrale haute résolution et temps-fréquence pour l'analyse de signaux de mesures de surface équivalente radar, SER, non stationnaires." Bordeaux 1, 1994. http://www.theses.fr/1994BOR10535.
Despinoy, Marc. "Potentiel de la télédétection haute résolution spatiale et spectrale en milieu intertropical : une approche transdisciplinaire à partir d'expériences aéroportées à la Réunion et en Guyane française." La Réunion, 2000. http://elgebar.univ-reunion.fr/login?url=http://thesesenligne.univ.run/00_14_despinoy.pdf.
Bouvet, Michel. "Études de certains problèmes de détection et normalisation adaptatives : application à l'acoustique sous-marine." Paris 11, 1987. http://www.theses.fr/1987PA112173.
Detection and estimation of spectral lines appear to be no longer feasible by using Fourier transform based methods when their separation becomes too poor. Parametric spectral methods can be used to increase the resolution at the condition that the a priori parametric model fits the observation. When an AR model can be used, the linear prediction methods give an optimal and simple solution. We emphasize here the sinusoïd plus noise model, that typically fits signals with great coherence time. In a synthetic presentation, this gathers the principal existing methods. Comparisons are made on principles, performances and implementations. The discussion is based either on original theoretical results or simulations
Kanani, Keyvan. "Utilisation de la très haute résolution spectrale pour la mesure en environnement extérieur de l'émissivité de surface dans la bande infrarouge 3-13 Mum : Méthodes et validation expérimentale." Université Louis Pasteur (Strasbourg) (1971-2008), 2005. https://publication-theses.unistra.fr/public/theses_doctorat/2005/KANANI_Keyvan_2005.pdf.
Emissivity is an optical property of materials, related to their ability to emit electromagnetic radiation. This PhD is devoted to retrieving emissivities of outdoor surfaces from high spectral resolution (4cm-1) spectroradiometric measurements at ground level, in the 750 cm-1 to 3500 cm-1 (3-13µm) spectral range. The main objective of this work, which combines theoretical and experimental approaches, is to define and assess a methodology. Two emissivity-temperature separation techniques are addressed, the Spectral Smoothness Method (SpSm) and the Multi-Temperatures Method (MTM), with particular attention paid to extending their usual domain of application on the short wavelength side beyond 1250cm-1. Sources of errors are identified and an experimental approach to mitigate errors on the determination of the irradiance of the surface is proposed. A new method, named Smoothness and Continuity (SmaC), is introduced, which takes into account the directional behaviour of the observed surface, to improve emissivity retrieval in the mid-infrared band (MWIR from 2000 to 3000 cm-1)To quantitatively assess the retrieval methods and validate the measurement protocol, a field campaign, that took place in June 2004, aimed at providing an error budget of the methods by measuring emissivities of several samples at different times of day. SpSm, applied to the campaign measurements, provides very good results in the LWIR band (from 750 to 1300 cm-1). In the MWIR band, systematic spectral discontinuities and deviations to laboratory measurements are observed in the retrieved spectra. This is interpreted as a manifestation of angular dependence of emissivity: the new SmaC method, through the introduction of a surface form factor, leads to significantly improved results. The standard deviation of the retrieved emissivity spectra over all measurements and samples is less than 0. 01 in LWIR and less than 0. 03 in MWIR. MTM results are less satisfactory than SpSm ones, due to ill-conditioned system of equations. Finally, a numerical analysis is carried out to confirm and validate SmaC hypothesis and findings
Brousseau, Christian. "Définition, Réalisation et Tests d'un radar VHF Multifréquence et Multipolarisation - Projet MOSAR." Phd thesis, Université Rennes 1, 1995. http://tel.archives-ouvertes.fr/tel-00085136.
Ce système dénommé M.O.S.A.R. (Maquette Orientée pour un Système d'Analyse de Résonances) a pour objectif la mesure des sections efficaces radars d'avions dans cette gamme de fréquence, afin de fournir l'ensemble des connaissances qui permettront de concevoir un futur radar opérationnel, destiné à la détection et à l'identification des cibles aériennes.
Dans un premier temps, nous définissons les caractéristiques principales du système, telles que la largeur de l'impulsion émise, la période de récurrence, le nombre de fréquences utilisées, ... . Ensuite, nous construisons un radar à impulsions, monostatique, cohérent, commandé par ordinateur, capable de mesurer et d'enregistrer les signaux rétrodiffusés par des avions. Ce système emploie deux réseaux d'antennes différents pour l'émission et la réception, chacun de ces réseaux utilisant respectivement quatre antennes log-périodiques dipolaires. Les informations relatives aux cibles (amplitude, phase et fréquence Doppler) sont ensuite extraites par une analyse spectrale non linéaire haute résolution.
Nous évaluons les performances du radar et précisons les limites du système. Enfin, des résultats expérimentaux sont présentés et confirment les choix dans la définition et la réalisation du radar.
Rachet, Florent. "Etude à très haute résolution des paramètres des raies spectrales." Paris 6, 1995. http://www.theses.fr/1995PA066187.
Bouchard, Simon. "Localisation haute-résolution de sources sonores à raies spectrales non-stationnaire." Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38223.
Grec, Catherine. "Étude à haute résolution angulaire de la granulation photosphérique solaire par une technique interspectrale." Nice, 2008. http://www.theses.fr/2008NICE4109.
The sun is a unique in situ laboratory, and solar physics plays an essential role in the domain of astrophysics, particles and high energies physics. To understand the convectives and magnetic properties of solar-type stars, as well as the solar activity, variability, and its influence on the earth environment, a global knowledge of our star is necessary, from its core to its high atmosphere. The visible surface layers of the quiet sun are analysed here thanks to a new super-resolving interspectral technique, inspired by the differential interferometry methods developed in stellar physics. This approach serves for testing a 3d magneto-hydrodynamic simulation of the solar granulation coupled with multi-dimensional radiative transfer calculations. It may also constrain inversion codes used for studying quiet sun magnetic fields. Observations of the granulation realized with THEMIS and HINODE show that granular structures visible at different photospheric depths appear displaced on the solar disk. This 3-dimensional effect is detected by cross-correlating monochromatic images obtained out of the solar disk center, and for successive wavelengths across a line profile. Once line profile distortions produced by granular velocity fields are corrected, we estimate the difference of formation depths of the continuous and different spectral lines (Fel 630 nm, Fel 557. 6 nm), as well as the difference of the 630 nm doublet line cores formation depths. Furthermore, we point out of the fact the combination of Doppler line shifts due to horizontal velocities, and mid-photospheric reversed granulation, could affect granules appearance all over the solar disk
Masson, Théo. "Fusion de données de télédétection haute résolution pour le suivi de la neige." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAT112/document.
Remote sensing acquisitions have complementary characteristics in terms of spatial and temporal resolution and can measure different aspects of snow cover (e.g., surface physical properties and snow type). By combining several acquisitions, it should be possible to obtain a precise and continuous monitoring of the snow. However, this task has to face the complexity of processing satellite images and the possible confusion between different materials observed. In particular, the estimation of fractional information, i.e., the amount of snow in each pixel, requires to know the proportion of the materials present in a scene. These proportions can be obtained performing spectral unmixing. The challenge is then to effectively exploit the information of different natures that are provided by the multiple acquisitions in order to produce accurate snow maps.Three main objectives are addressed by this thesis and can be summarized by the three following questions:- What are the current limitations of state-of-the-art techniques for the estimation of snow cover extent from optical observations?- How to exploit a time series for coping with the spectral variability of materials?- How can we take advantage of multimodal acquisitions from optical sensors for estimating snow cover maps?A complete study of the various snow products from the MODIS satellite is proposed. It allows the identification of numerous limitations, the main one being the high rate of errors during the estimation of the snow fraction (approximately 30%).The experimental analysis allowed to highlight the sensitivity of the spectral unmixing methods against the spectral variability of materials.Given these limitations, we have exploited the MODIS time series to propose a new endmembers estimation approach, addressing a critical step in spectral unmixing. The low temporal evolution of the medium (except snow) is then used to constrain the estimation of the endmembers not only on the image of interest, but also on images of the previous days. The effectiveness of this approach, although demonstrated here, remains limited by the spatial resolution of the sensor.Data fusion has been considered aiming at taking advantage of multiple acquisitions with different characteristics in term of resolution available on the same scene. Given the limitations of the actual methods in the case of multispectral sensors, a new fusion approach has been proposed. Through the formulation of a new model and its resolution, the fusion between optical sensors of all types can be achieved without consideration of their characteristics. The various experiments on the estimation of snow maps show a clear interest of a better spatial resolution to isolate the snow covered areas. The improvement in spectral resolution will improve future approaches based on spectral unmixing.This work explores the new possibilities of development for the observation of snow, but also for the combined use of the satellite images for the observation of the Earth in general
Alalam, Perla. "Étude des aérosols à partir de mesures en laboratoire et IASI : application aux déserts d'Asie de l'Est." Electronic Thesis or Diss., Université de Lille (2022-....), 2022. http://www.theses.fr/2022ULILR052.
East Asia is the second largest source of mineral-type aerosols in the world after the Sahara. These can modify the Earth's radiative balance due to their properties of absorption and diffusion of atmospheric radiation. Therefore, precise information on the physico-chemical properties of desert dust is essential to understand and better quantify their impact on the atmosphere. In this context, this thesis aims to test the potential of a new methodological approach combining laboratory measurements and satellite remote sensing for better characterization of aerosols from desert and semi-arid surfaces. Its application concerns studying desert storm events in East Asia from the IASI space instrument.One of the major difficulties of this work comes from the fact that the mineral dust emitted in this region is emitted mainly above the continental surface and in the lower troposphere, which poses constraints linked, on the one hand, to a low sensitivity due to a lack of thermal contrast and on the other hand due to the great influence and variability of the Earth's surface emissivity (LSE). Thus, the first part of this work focused on improving the consideration of LSE by developing a new methodology from a set of average monthly emissivity data.Then, experimental extinction coefficients of pure minerals were linearly combined to reproduce a spectrum of Gobi dust, which made it possible to obtain the mineralogical mass fractions. In addition, from the IASI radiances, an optical thickness of Gobi dust was calculated, displaying characteristics identical to those measured in the laboratory. The linear combination of pure mineral spectra was then applied to IASI optical thickness, providing mineralogical mass fractions. Finally, the entire methodology was applied to two dust events during two different seasons and years: May 2017 and March 2021. The method made it possible to obtain the first spatial and temporal distributions of the chemical composition of desert aerosols. The average mass fractions obtained for particles from the Gobi Desert, Taklamakan Desert, and Horqin Sandy Land are close to mass fractions from the literature. In addition, these results on the chemical composition made it possible to link aerosols' spatial variability to dust emission sources, confirmed using a retro-trajectory model. In addition, comparing two IASI instruments on MetOp A and B showed good consistency, allowing us to consider the method's applicability to different MetOp platforms having the same instrument type. The results presented in this manuscript represent an important advance in improving the characterization of desert aerosols by space remote sensing, in particular concerning the analysis of the chemical composition
Mees, Wim. "Contribution à l'analyse distribuée de scènes : application aux images satellitaires multi spectrales, haute résolution." Nancy 1, 2000. http://www.theses.fr/2000NAN10282.
Flaud, Pierre-Marie. "Développement et caractérisation d'un spectromètre laser infrarouge par différence de fréquences : application à la spectroscopie infrarouge à très haute résolution." Paris 11, 2005. http://www.theses.fr/2005PA112285.
For laboratory studies and field measurements of atmospheric molecules, single-mode tuneable lasers are more and more used, in order to complete other instruments such as Fourier-transform spectrometers because of their limitations (in particular spectral resolution and signal-to-noise ratio that have an important impact on the accurate determination of molecular line parameters). We report here the development and characterization of a compact tuneable continuous-wave infrared laser, based on difference-frequency generation (DFG) using quasi phase-matching in periodically poled LiNbO3 (PPLN). Several 0. 1 microW of infrared radiation (tuneable in the 1800 à 3100 cm-1 range) are obtained using a diode-pumped Nd:YAG laser (output power about 800 mW at 1064 nm, linewidth 1 kHz) together with a tuneable external-cavity diode laser (output power about 10-50 mW in the 805-885 nm region, linewidth 1 MHz). Using this infrared DFG laser for absorption experiments of gas-phase molecules, both very high resolution (1 MHz) and a high signal-to-noise ratio (up to several 1000) can be achieved in measurement time of only a few minutes, as demonstrated using absorption spectra of N2O in different wavelength regions. Using this laser we have determined absolute intensities of infrared lines of NO2 (using a UV-visible set-up to measure the NO2 amounts) observing a systematic difference of about 5 % with respect to the HITRAN 2004 database. We have used the same laser for the first observation of collisional line-mixing between nuclear hyperfine components of HI lines (a phenomenon predicted over 20 years ago)
Djath, Bughsin'. "Etude de la dynamique océanique de la mer des Salomon : modélisation numérique à haute résolution." Phd thesis, Université de Grenoble, 2014. http://tel.archives-ouvertes.fr/tel-01069989.
Osman, Julien. "Connaissances expertes et modélisation pour l'exploitation d'images d'observation de la Terre à hautes résolutions spatiale, spectrale et temporelle." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30022/document.
The future Earth observation space missions, Venµs and Sentinel (1 and 2), will provide us with a flow of data unseen in terms of spatial, spectral and temporal resolution. To use these data efficiently for the generation of land cover maps or change detection, we need fast, robust approaches that require as little supervision as possible. For instance, a concrete use of these data could be the identification, as early as May, of the area growing corn in all the South-West part of France. Or obtaining a monthly land cover map, in a slight delay, on large areas. Images alone don't allow us to reach such goals. Nevertheless, other information is available, which hasn't been really used. The main goal of this thesis is to identify available prior information, evaluate its revelance, and introduce it in preexisting processing chains to assess its contribution. We focused on agriculture monitoring. The information we used is knowledge on farming practices (crop rotations, irrigation, crop class alternation, etc) and the size and the topography of the fields. We mainly worked with 2 sources of prior knowledge: * Knowledge contained in databases such as the Registre Parcellaire Graphique (RPG). We used data mining methods to extract it. * Knowledge provided by experts. We modeled it with 1\up{st} order logic rules. One contribution of this thesis is the selection and assessment of a tool allowing us to extract and process information in a way that we can introduce it efficiently in preexisting classification algorithms: Markov Logic. Markov Logic is a statistical tool able to work with both information from databases and information modeled with logic rules. We show that using these data increases the quality of the land cover maps. We also show that this information allows us to obtain real time maps, whose quality increases with the arrival of new information. As a conclusion of this thesis work, we provide outlooks for applying the same methodology to other areas, such as the monitoring of tropical forests dans generic land cover mapping
Gobron, Olivier. "Lasers ultra-stables asservis sur trous-brûlés spectraux : développement en vue d'une application aux horloges optiques." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066034/document.
Optical lattice clocks show impressive performances and are begining to raise the question of the redefinition of the SI second. In these systems, an ultra-stable laser is used as local oscillator to probe very narrow optical transitions of neutral atoms trapped in an optical lattice. The ultime stability of these systems, determined by the number of atoms interrogated at each clock cycle, evaluated at a few 10−17/sqrt(tau) (where tau is the integration time), is currently not reached and is limited to a few 10−16/sqrt(tau) by the phase fluctuations of the probe laser. If the enhancement of the ultra-stable cavities, on which are currently stabilized the probe lasers, is widely studied, LNE-SYRTE has adopted a more recent approach where the frequency reference is a spectral hole burned in rare earth doped crystal cooled down at cryogenic temperature (around 4 K). A short term stability of a few 10−18 could be achieved. This thesis describes the construction of the experiment and present the results of a high resolution spectroscopy of narrow spectral holes (FWHM = 3.3 kHz) burned in the crystal Eu3+ : Y2SiO5. The influence of the closed cycle cryostat on the behaviour of the spectral holes is hightlighted and reduced. Finally, an original locking scheme based on a heterodyne detection of a spectral hole and a numerical lock program using FPGA in order to stabilize the laser frequency on the top of the narrow spectral hole is described and shows a short term stability of a few 10−14, which is a first promising result for the future of the project
Talon, Hervé. "Aspects théoriques de la spectroscopie haute résolution de la phase dense : creusement de trous spectraux et spectroscopie de molécules individuelles." Bordeaux 1, 1992. http://www.theses.fr/1992BOR10557.
Lachérade, Sophie. "Caractérisation des propriétés optiques des matériaux urbains à partir d'images de télédétection à très hautes résolutions spatiale et spectrale." Toulouse, ENSAE, 2006. http://www.theses.fr/2006ESAE0008.
Paulus, Caroline. "Filtrage de données sismiques multicomposantes et estimation de la polarisation." Phd thesis, Grenoble INPG, 2006. http://tel.archives-ouvertes.fr/tel-00204504.
Ils peuvent enregistrer le déplacement dans plusieurs directions de l'espace ainsi que les variations de pression.
Le développement de traitements adaptés à ce type de données est nécessaire.
Le but de ce travail de thèse est de développer une méthode permettant d'une part le débruitage de données sismiques multicomposantes, la séparation des différents champs d'ondes ou encore l'estimation de la polarisation des ondes et de leur direction d'arrivée (DOA).
Cette méthode, appelée filtrage matriciel large-bande multicomposante, dérivée de la méthode monocomposante, prend en compte l'information de polarisation et traite les différentes composantes de façon globale et non indépendamment.
Le principe utilisé est celui de la décomposition en valeurs propres d'une matrice spectrale pour permettre une séparation efficace de l'espace des données de départ en deux espaces complémentaires (sous-espace signal et sous-espace bruit).
Chane, Camille. "Intégration de systèmes d'acquisition de données spatiales et spectrales haute résolution, dans le cadre de la génération d'informations appliquées à la conservation du patrimoine." Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00909743.
Simon, Chane Camille. "Intégration de systèmes d'acquisition de données spatiales et spectrales haute résolution, dans le cadre de la génération d'informations appliquées à la conservation du patrimoine." Thesis, Dijon, 2013. http://www.theses.fr/2013DIJOS008/document.
The concern and interest of this PhD thesis is the registration of featureless 3D and multispectral datasets describing cultural heritage objects.In this context, there are few natural salient features between the complementary datasets, and the use of targets is generally proscribed.We thus develop a technique based on the photogrammetric tracking of the acquisition systems in use.A series of simulations was performed to evaluate the accuracy of our method in three configurations chosen to represent a variety of cultural heritage objects.These simulations show that we can achieve a spatial tracking accuracy of 0.020 mm and an angular accuracy of 0.100 mrad using four 5 Mpx cameras when digitizing an area of 400 mm x 700 mm. The accuracy of the final registration relies on the success of a series of optical and geometrical calibrations and their stability for the duration of the full acquisition process.The accuracy of the tracking and registration was extensively tested in laboratory settings. We first evaluated the potential for multiview 3D registration. Then, the method was used for to project of multispectral images on 3D models.Finally, we used the registered data to improve the reflectance estimation from the multispectral datasets
Cladé, Sophie. "Synthèse d'ouverture optique pour l'observation à haute résolution du soleil : étude des systèmes de correction de front d'onde et de filtrage spectral de l'instrument." Paris 11, 2005. http://www.theses.fr/2005PA112196.
To reach a high spatial resolution on solar observation, an interferometric system made of three telescopes is proposed. This optical aperture synthesis method let us improve the spatial resolution without being limited by the weight or the size of the instrument. Some pointing and cophasing systems are needed to keep a good image quality. High spectral resolution is reached with a system composed of 2 identical gratings. An optical bench has been installed in the Meudon Observatory to demonstrate the validity of the instrument's technical concepts. In this document, I first introduce the characteristics and the reasons of SOLARNET's technical concepts. In the second part, I present the optical bench and detail the alignment methods and their precisions. The third part is dedicated to the pointing system. I study the closed loop, do some simulations and experimental tests that show that the limited correction is due to the limited speed of the mirror. I then present the cophasing system that uses white light interferometric measurement. Simulation of this system show that there is a possible bias on the measure. If experimental tests confirm this bias, there should be an system to correct it. The results of my simulation give the basis to define this new system. In the last part of the document, I describe the optical study and the optimisation I made on the imaging spectrometric part of the instrument
Rodes, Arnau Isabel. "Estimation de l'occupation des sols à grande échelle pour l'exploitation d'images d'observation de la Terre à hautes résolutions spatiale, spectrale et temporelle." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30375/document.
The new generation Earth observation missions such as Sentinel-2 (a twin-satellite initiative prepared by the European Space Agency, ESA, in the frame of the Copernicus programme, previously known as Global Monitoring for Environment and Security or GMES) and Venµs, jointly developed by the French Space Agency (Centre National d'Études Spatiales, CNES) and the Israeli Space Agency (ISA), will revolutionize present-day environmental monitoring with the yielding of unseen volumes of data in terms of spectral richness, temporal revisit and spatial resolution. Venµs will deliver images in 12 spectral bands from 412 to 910 nm, a repetitivity of 2 days, and a spatial resolution of 10 m; the twin Sentinel-2 satellites will provide coverage in 13 spectral bands from 443 to 2200 nm, with a repetitivity of 5 days, and spatial resolutions of 10 to 60m. The efficient production of land cover maps based on the exploitation of such volumes of information for large areas is challenging both in terms of processing costs and data variability. In general, conventional methods either make use of supervised approaches (too costly in terms of manual work for large areas), target specialised local models for precise problem areas (not applicable to other terrains or applications), or include complex physical models with inhibitory processing costs. These existent present-day approaches are thus inefficient for the exploitation of the new type of data that the new missions will provide, and a need arises for the implementation of accurate, fast and minimally supervised methods that allow for generalisation to large scale areas with high resolutions. In order to allow for the exploitation of the previously described volumes of data, the objective of this thesis is the conception, design, and validation of a fully automatic approach that allows the estimation of large-area land cover with high spatial, spectral and temporal resolution Earth observation imagery, being generalisable to different landscapes, and offering operational computation times with simulated satellite data sets, in preparation of the coming missions