Made available in DSpace on 2014-10-09T12:44:16Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:43Z (GMT). No. of bitstreams: 1 06896.pdf: 4262092 bytes, checksum: a107ec0ad6ce79bad3021b2d96ac0cc6 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Dissertacao [Mestrado] / IEA/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP / FAPESP:98/01953-0

Made available in DSpace on 2014-10-09T12:54:28Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:03Z (GMT). No. of bitstreams: 0 / Nos últimos anos, problemas relacionados à contaminação de alimentos por substâncias ou elementos que podem ser um risco a saúde humana são uma preocupação não somente das autoridades governamentais, mas também da própria população. Dentro deste contexto, as embalagens plásticas podem constituir uma fonte de contaminação de alimentos uma vez que o processo de produção de plásticos envolve o uso de catalisadores e dos mais variados tipos de aditivos os quais podem conter elementos tóxicos. Quando os alimentos entram em contato com estas embalagens, seus componentes podem migrar para o alimento. No Brasil, para o controle dos materiais a serem utilizados para embalagens de alimentos, a Agência Nacional de Vigilância Sanitária (ANVISA) estabeleceu valores limites de substâncias migrantes e procedimentos para determinação da migração de elementos e substâncias das embalagens plásticas para os alimentos. No presente estudo, o método radiométrico foi avaliado para determinação da migração de elementos das embalagens plásticas para simulantes de alimentos ou para o próprio alimento. Este método radiométrico consistiu na irradiação das amostras de embalagens plásticas com um fluxo de nêutrons térmicos do reator de pesquisa IEA-R1 para produzir os radioisótopos dos elementos presentes nessas embalagens. A seguir, o plástico irradiado foi exposto à migração do elemento para o simulante ou para o alimento. A migração foi determinada pela medição da radioatividade no simulante ou no alimento pela espectrometria de raios gama. Os tipos de simulantes de alimentos e as condições experimentais foram estabelecidos de II acordo com o regulamento da ANVISA. A migração de elementos foi estudada para embalagens plásticas de refrigerantes, água, leite, derivados de leite, sucos e alimentos gordurosos. Na análise por ativação com nêutrons destas embalagens foi verificada a presença de elementos como As, Cd, Cr, Co e Sb. Os resultados da migração obtidos pelo método radiométrico indicaram que Cd, Co, Cr e Sb presentes nos plásticos migram tanto para o simulante como para o alimento. Nem todas as embalagens apresentaram migração destes elementos e nestes casos foram determinados os valores limites de detecção. Os resultados das análises das embalagens plásticas irradiadas com nêutrons por calorimetria exploratória diferencial e por espectroscopia no infravermelho por transformada de Fourier mostraram que na embalagem de polietileno de alta densidade pode ocorrer a degradação oxidativa. Entre as principais vantagens do método radiométrico na avaliação da migração estão a sua simplicidade, a não necessidade da análise do branco e a possibilidade de determinar a migração no próprio alimento. Os resultados obtidos indicaram a potencialidade do uso deste método na avaliação da migração de elementos das embalagens plásticas para o seu conteúdo. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:26:28Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:41Z (GMT). No. of bitstreams: 0 / A fototerapia é um procedimento estabelecido há mais de 50 anos no tratamento da icterícia em recém-nascidos. No entanto ainda não há um método padronizado de quantificação da dose fototerápica nos estudos clínicos publicados, dificultando a comparação de estudos prévios sobre a eficácia da fototerapia, bem como o estabelecimento de doses seguras e previsíveis. A dose fototerápica depende, dentre outros fatores, da irradiância média útil entregue pelas unidades fototerápicas. Mas não há procedimentos padronizados tanto na quantificação da irradiância útil ao tratamento, quanto na estimação da irradiância média útil em fontes fototerápicas. Por isso, têm sido relatadas grandes variações nas medições de uma mesma fonte usando os radiômetros disponíveis no mercado, como conseqüência da vasta diversidade de responsividades espectrais dos instrumentos. Um objetivo deste trabalho foi adaptar e aplicar os princípios da radiometria ultravioleta de banda larga na quantificação da irradiância disponível em fontes fototerápicas, estabelecendo procedimentos que permitem comparar irradiâncias medidas em diversas fontes, usando radiômetros com diferentes responsividades espectrais. Outro objetivo foi caracterizar amostras de fontes comumente usadas atualmente, focando o problema da estimação da irradiância média útil em unidades de fototerapia, propondo um método de estimação da irradiância média útil em fontes com foco dirigido. Os resultados experimentais obtidos nos permitem concluir que não somente é necessário padronizar a radiometria fototerápica, como também o método de estimação da irradiância média útil. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2015-12-22T09:13:03Z No. of bitstreams: 0 / Made available in DSpace on 2015-12-22T09:13:03Z (GMT). No. of bitstreams: 0 / A aceitação de rejeitos radioativos em um repositório final depende, entre outras coisas, do conhecimento do inventário radioisotópico presente neles. Para obter essa informação, é necessário fazer a caracterização primária dos rejeitos de modo que a composição seja conhecida e oriente os passos seguintes da gestão. Os filtros cartucho que são utilizados no sistema de retratamento de água do reator de pesquisa IEA-R1 é um desses rejeitos. O IEA-R1 é um reator de pesquisa do tipo piscina, operando entre 2 e 5 MW, que utiliza a água como líquido de arrefecimento, moderador e blindagem biológica Além do seu uso em pesquisa, também é utilizado para produzir radioisótopos e irradiar amostras. Ele está localizado no Instituto de Pesquisas Energéticas e Nuclear, no campus da Universidade de São Paulo. Os filtros cartucho são utilizados para reter o material particulado em suspensão presente na água. Quando os filtros ficam saturados e são incapazes de manter o fluxo dentro dos limites estabelecidos, eles são substituídos e descartados como rejeito radioativo. Após um período de espera para o decaimento da atividade, são enviados para Gerência de Rejeitos Radioativos (GRR). O objetivo deste trabalho é apresentar os estudos realizados para determinar a atividade dos emissores gama presentes nos filtros cartucho. As atividades foram calculadas utilizando as taxas de dose medidas com detectores portáteis, as relações entre as taxas de emissão de fótons avaliadas por espectrometria gama, e o método de Point Kernel, que correlaciona a atividade de uma fonte com as taxas de dose a várias distâncias. O método descrito pode ser utilizado para determinar de modo rotineiro o inventário radioisotópico destes filtros, dispensando análises radioquímicas destrutivas, e a necessidade de calibração da geometria de medição. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / O presente documento apresenta as caracterÃsticas mineralÃgicas e tecnolÃgicas de um diabÃsio, cujo afloramento, sob a forma de dique, està localizado no distrito de CanafÃstula, em ApuiarÃs â CE. Com o intuito de avaliar suas qualidades para aplicaÃÃo como rocha ornamental, foram efetuados ensaios tecnolÃgicos de Ãndices fÃsicos e fÃsico-mecÃnicos, baseados em normas da ABNT, assim como mediÃÃes radiomÃtricas da quantidade de urÃnio, tÃrio e potÃssio radioativos presentes na rocha, alÃm da taxa de exalaÃÃo de radÃnio. As mediÃÃes radiomÃtricas foram realizadas atravÃs da aplicaÃÃo de mÃtodos de espectrometria gama e de detecÃÃo ativa de exalaÃÃo do gÃs radÃnio para o monitoramento da quantidade de 222Rn. Adicionado aos principais objetivos deste trabalho foram tambÃm efetuadas anÃlises petrogrÃficas voltadas ao reconhecimento da composiÃÃo mineralÃgica e feiÃÃes texturais dentre outras caracterÃsticas. As anÃlises petrogrÃficas permitiram classificar a rocha como olivina diabÃsio, com textura porfirÃtica, mineralogicamente composto por titanaugita + plagioclÃsio + olivina + opacos + apatita  iddingsita  clorofeÃta  biotita. Tal litotipo possui cor cinza que varia a preto, com estrutura isotrÃpica. O grau de microfissuramento da rocha situa-se em torno de 3,53/mmÂ, em que 97,9% das fissuras sÃo do tipo intragrÃo e 2,1% sÃo do tipo intergrÃo. Os Ãndices fÃsicos apresentaram valores superiores a mÃdia para rochas siliciclÃsticas brasileiras, quais sejam, massa especifica aparente, porosidade e absorÃÃo dâÃgua respectivamente com 3113 kg/mÂ, 0,17% e 0,06%. Os valores de resistÃncia à compressÃo uniaxial tambÃm superam a mÃdia para rochas siliciclÃsticas brasileiras e tambÃm dentro dos limites da ASTM, com uma Ãtima resistÃncia a compressÃo de 192 MPa. Com relaÃÃo ao ensaio de flexÃo 3 pontos, a rocha exibiu valor de 20,4 MPa, bem superior a mÃdia para rochas siliciclÃsticas brasileiras e ASTM. O comportamento das amostras quando submetidas ao desgaste AMSLER, forneceu um desempenho com 0,66mm de desgaste para um percurso de 1000m, abaixo da mÃdia para rochas siliciclÃsticas brasileiras. As anÃlises por espectrometria gama forneceram valores para 238U e 40K, de 0,54 ppm e 2,88 %, e quando transformados para Bq.kg-1, corresponderam a 6,8 e 48,3, respectivamente. A atividade de final de emanaÃÃo de radÃnio (CRn) e taxa de exalaÃÃo de radÃnio (E) registraram, conteÃdos de <0,016 Bq.kg-1 (<0,432 pCi.kg-1) e <0,002 Bq.m-2h-1 (<0,054 pCi.m-2.h-1). Dentro deste contexto, o olivina diabÃsio porfiritico demonstrou possuir aplicaÃÃes diversificadas como material ornamental pelas Ãtimas caracterÃsticas mecÃnicas e baixa concentraÃÃes de elementos radioativos, bem como baixa emanaÃÃo e exalaÃÃo de 222Rn, isso devido a suas caracterÃsticas de material de composiÃÃo bÃsica, boa resistÃncia mecÃnica, baixa porosidade e baixa quantidade de microfissuramento / This paper presents the technological and mineralogical characteristics of a diabase, which outcrop in the form of dike is located in the district CanafÃstula in ApuiarÃs - CE. In order to assess their qualities for application as ornamental, were carried out technological tests of fitness levels and physical-mechanical, based on standards from ABNT, as well as radiometric measurements of the amount of uranium, thorium and radioactive potassium in the rock, beyond radon exhalation rate. The radiometric measurements were performed using the methods of gamma spectrometry and detection of active exhalation of radon gas to monitor the amount of 222Rn. Added to the main objectives of this study were also made petrographic directed to the recognition of the mineralogical composition and textural features among other features. The petrographic analysis allowed to classify the rock as olivine diabase, porphyritic texture, composed of mineralogically titanaugita olivine + plagioclase + + + apatite  opaque  iddingsita clorofeÃta  biotite. This has lithotype ranging gray to black, with isotropic structure. The degree of microcracking of the rock is located around 3.53 / mm Â, where 97.9% of the cracks are of the type intragrÃo and 2.1% are of the intergrain. The physical indices showed higher than average for siliciclastic rocks in Brazil, namely, apparent specific gravity, porosity and water absorption with respectively 3113 kg / mÂ, 0.17% and 0.06%. The values of uniaxial compressive strength also exceed the average for Brazilian siliciclastic rocks and also within the limits of ASTM, with an excellent compressive strength of 192 MPa. Regarding the 3-point bending test, the rock exhibited value of 20.4 MPa, well above the average for Brazilian siliciclastic rocks and ASTM. The behavior of the samples when subjected to wear AMSLER, gave a performance with 0.66 mm wear for a journey of 1000m below the average for Brazilian siliciclastic rocks. The analysis by gamma spectrometry provided values for 238U and 40K, of 0.54 ppm and 2.88%, and when transformed into Bq.kg-1, corresponded to 6.8 and 48.3, respectively. The final activity of radon emanation (CRN) and radon exhalation rate (E) registered a content of <0.016 Bq.kg-1 (<0.432 pCi.kg-1) and <0.002 Bq.m-2h-1 (<0.054 pCi.m-2.h-1).Within this context, the olivine diabase porphyry shown to have diverse applications such as ornamental material for optimal mechanical characteristics and low concentrations of radioactive elements as well as low emanation and exhalation of 222Rn, that due to its material characteristics of basic composition, good mechanical strength, low porosity and low amount of microcracking

This thesis deals with gamma-ray field of size-limited uranium objects and with possibilities of their localization by a field radiometric measurement. The gamma-ray field attenuates progressively with distance from the ground source of radiation. The applied method of radiometric survey plays an important role in localization of a radioactive object. The gamma- ray field of uranium anomalous objects was studied for variable signatures of ground anomalous objects and different methods of gamma-ray survey by using mathematical modelling. The method of modelling was derived from fundamental theoretical laws describing the gamma-ray field of a point source. The verification of applied mathematical modelling was carried out by the comparison of calculated model of the gamma-ray field at three real uranium anomalous objects with experimental data of ground and mini-airborne measurement. Mini-airborne measurement was realized by the prototype of a gamma spectrometer Georadis D230A. This instrument is characterized by relatively high sensitivity compared to previously used similar devices. Airborne platform was a hexacopter Kingfischer. One of the aims of this thesis was to assess the applicability and technical capacity of D230A instrument. Calculated values of the gamma-ray field at different detection...

This dissertation provides a robust radiometric calibration for the TRMM Microwave Imager to correct systematic brightness temperature errors, which vary dynamically with orbit position (time) and day of the year. The presence of a time-varying bias in TMI is confirmed by inter-calibration with WindSat and SSMI. This time varying bias is manifested as a time of day dependent variation of the relative biases between TMI and both WindSat and SSMI. In this dissertation, we provide convincing evidence that this time-varying Tb bias in TMI is caused by variations in the physical temperature of the emissive TMI reflector antenna. This dissertation provides an empirical correction that largely corrects this time-varying bias. The TMI bias is estimated by comparing the 10.7 GHz V-polarization channel observations with RTM Tb predictions, and the Tb correction is applied as a function of orbit time for every day of the one year period. Furthermore, this dissertation provides a qualitative physical basis for the estimated Tb bias patterns and provides conclusive evidence that the empirical correction applied to TMI Tb measurements (both ocean and land) largely corrects the time-varying TMI calibration. This is accomplished by demonstrating that the local time-of-day dependence (in the uncorrected TMI Tb values) is removed in the corrected TMI Tb's.

No description available.

Two aspects of the study of the Earth radiation budget and the effects of clouds on our climate system are considered in this dissertation : instrumentation and data interpretation. Numerical models have been developed to characterize the optical/thermal-radiative behavior, the dynamic electrothermal response and the structural thermal transients of radiometric channels. These models, applied to a satellite-borne scanning radiometer, are used to determine the instrument point spread function and the potential for optical and thermal-radiative contamination of the signal due to out-of-field radiation and emission from the radiometer structure. The capabilities of the model are demonstrated by scanning realistic Earth scenes. In addition, the optical/thermal-radiative model is used for the development of an infrared field radiometer to interpret results from the experimental characterization of the instrument. The model allowed the sensitivity of the instrument response to assembly uncertainties to be determined. Data processing consists of converting radiometric data into estimates of the flux at the top of the atmosphere. Primary error sources are associated with the procedures used to compensate for unsampled data. The time interpolation algorithm applied to a limited number of observations can produce significantly biased estimates of monthly mean fluxes. A diurnal interpolation protocol using correlative ISCCP cloudiness data is developed to compensate for sparse temporal sampling of Earth radiation budget data. The bias is shown to be significantly reduced in regions where the variability of the cloud cover is well accounted for by ISCCP data. / Ph. D.

Les images satellitales multispectrales, notamment celles à haute résolution spatiale (plus fine que 30 m au sol), représentent une source d’information inestimable pour la prise de décision dans divers domaines liés à la gestion des ressources naturelles, à la préservation de l’environnement ou à l’aménagement et la gestion des centres urbains. Les échelles d’étude peuvent aller du local (résolutions plus fines que 5 m) à des échelles régionales (résolutions plus grossières que 5 m). Ces images caractérisent la variation de la réflectance des objets dans le spectre qui est l’information clé pour un grand nombre d’applications de ces données. Or, les mesures des capteurs satellitaux sont aussi affectées par des facteurs « parasites » liés aux conditions d’éclairement et d’observation, à l’atmosphère, à la topographie et aux propriétés des capteurs. Deux questions nous ont préoccupé dans cette recherche. Quelle est la meilleure approche pour restituer les réflectances au sol à partir des valeurs numériques enregistrées par les capteurs tenant compte des ces facteurs parasites ? Cette restitution est-elle la condition sine qua non pour extraire une information fiable des images en fonction des problématiques propres aux différents domaines d’application des images (cartographie du territoire, monitoring de l’environnement, suivi des changements du paysage, inventaires des ressources, etc.) ? Les recherches effectuées les 30 dernières années ont abouti à une série de techniques de correction des données des effets des facteurs parasites dont certaines permettent de restituer les réflectances au sol. Plusieurs questions sont cependant encore en suspens et d’autres nécessitent des approfondissements afin, d’une part d’améliorer la précision des résultats et d’autre part, de rendre ces techniques plus versatiles en les adaptant à un plus large éventail de conditions d’acquisition des données. Nous pouvons en mentionner quelques unes : - Comment prendre en compte des caractéristiques atmosphériques (notamment des particules d’aérosol) adaptées à des conditions locales et régionales et ne pas se fier à des modèles par défaut qui indiquent des tendances spatiotemporelles à long terme mais s’ajustent mal à des observations instantanées et restreintes spatialement ? - Comment tenir compte des effets de « contamination » du signal provenant de l’objet visé par le capteur par les signaux provenant des objets environnant (effet d’adjacence) ? ce phénomène devient très important pour des images de résolution plus fine que 5 m; - Quels sont les effets des angles de visée des capteurs hors nadir qui sont de plus en plus présents puisqu’ils offrent une meilleure résolution temporelle et la possibilité d’obtenir des couples d’images stéréoscopiques ? - Comment augmenter l’efficacité des techniques de traitement et d’analyse automatique des images multispectrales à des terrains accidentés et montagneux tenant compte des effets multiples du relief topographique sur le signal capté à distance ? D’autre part, malgré les nombreuses démonstrations par des chercheurs que l’information extraite des images satellitales peut être altérée à cause des tous ces facteurs parasites, force est de constater aujourd’hui que les corrections radiométriques demeurent peu utilisées sur une base routinière tel qu’est le cas pour les corrections géométriques. Pour ces dernières, les logiciels commerciaux de télédétection possèdent des algorithmes versatiles, puissants et à la portée des utilisateurs. Les algorithmes des corrections radiométriques, lorsqu’ils sont proposés, demeurent des boîtes noires peu flexibles nécessitant la plupart de temps des utilisateurs experts en la matière. Les objectifs que nous nous sommes fixés dans cette recherche sont les suivants : 1) Développer un logiciel de restitution des réflectances au sol tenant compte des questions posées ci-haut. Ce logiciel devait être suffisamment modulaire pour pouvoir le bonifier, l’améliorer et l’adapter à diverses problématiques d’application d’images satellitales; et 2) Appliquer ce logiciel dans différents contextes (urbain, agricole, forestier) et analyser les résultats obtenus afin d’évaluer le gain en précision de l’information extraite par des images satellitales transformées en images des réflectances au sol et par conséquent la nécessité d’opérer ainsi peu importe la problématique de l’application. Ainsi, à travers cette recherche, nous avons réalisé un outil de restitution de la réflectance au sol (la nouvelle version du logiciel REFLECT). Ce logiciel est basé sur la formulation (et les routines) du code 6S (Seconde Simulation du Signal Satellitaire dans le Spectre Solaire) et sur la méthode des cibles obscures pour l’estimation de l’épaisseur optique des aérosols (aerosol optical depth, AOD), qui est le facteur le plus difficile à corriger. Des améliorations substantielles ont été apportées aux modèles existants. Ces améliorations concernent essentiellement les propriétés des aérosols (intégration d’un modèle plus récent, amélioration de la recherche des cibles obscures pour l’estimation de l’AOD), la prise en compte de l’effet d’adjacence à l’aide d’un modèle de réflexion spéculaire, la prise en compte de la majorité des capteurs multispectraux à haute résolution (Landsat TM et ETM+, tous les HR de SPOT 1 à 5, EO-1 ALI et ASTER) et à très haute résolution (QuickBird et Ikonos) utilisés actuellement et la correction des effets topographiques l’aide d’un modèle qui sépare les composantes directe et diffuse du rayonnement solaire et qui s’adapte également à la canopée forestière. Les travaux de validation ont montré que la restitution de la réflectance au sol par REFLECT se fait avec une précision de l’ordre de ±0.01 unités de réflectance (pour les bandes spectrales du visible, PIR et MIR), même dans le cas d’une surface à topographie variable. Ce logiciel a permis de montrer, à travers des simulations de réflectances apparentes à quel point les facteurs parasites influant les valeurs numériques des images pouvaient modifier le signal utile qui est la réflectance au sol (erreurs de 10 à plus de 50%). REFLECT a également été utilisé pour voir l’importance de l’utilisation des réflectances au sol plutôt que les valeurs numériques brutes pour diverses applications courantes de la télédétection dans les domaines des classifications, du suivi des changements, de l’agriculture et de la foresterie. Dans la majorité des applications (suivi des changements par images multi-dates, utilisation d’indices de végétation, estimation de paramètres biophysiques, …), la correction des images est une opération cruciale pour obtenir des résultats fiables. D’un point de vue informatique, le logiciel REFLECT se présente comme une série de menus simples d’utilisation correspondant aux différentes étapes de saisie des intrants de la scène, calcul des transmittances gazeuses, estimation de l’AOD par la méthode des cibles obscures et enfin, l’application des corrections radiométriques à l’image, notamment par l’option rapide qui permet de traiter une image de 5000 par 5000 pixels en 15 minutes environ. Cette recherche ouvre une série de pistes pour d’autres améliorations des modèles et méthodes liés au domaine des corrections radiométriques, notamment en ce qui concerne l’intégration de la FDRB (fonction de distribution de la réflectance bidirectionnelle) dans la formulation, la prise en compte des nuages translucides à l’aide de la modélisation de la diffusion non sélective et l’automatisation de la méthode des pentes équivalentes proposée pour les corrections topographiques. / Multi-spectral satellite imagery, especially at high spatial resolution (finer than 30 m on the ground), represents an invaluable source of information for decision making in various domains in connection with natural resources management, environment preservation or urban planning and management. The mapping scales may range from local (finer resolution than 5 m) to regional (resolution coarser than 5m). The images are characterized by objects reflectance in the electromagnetic spectrum witch represents the key information in many applications. However, satellite sensor measurements are also affected by parasite input due to illumination and observation conditions, to the atmosphere, to topography and to sensor properties. Two questions have oriented this research. What is the best approach to retrieve surface reflectance with the measured values while taking into account these parasite factors? Is this retrieval a sine qua non condition for reliable image information extraction for the diverse domains of application for the images (mapping, environmental monitoring, landscape change detection, resources inventory, etc.)? Researches performed in the past 30 years have yielded a series of techniques to correct the parasite factors among which some allow to retrieve ground reflectance. Some questions are still unanswered and others require still more scrutiny to increase precision and to make these methods more versatile by adapting them to larger variety of data acquisition conditions. A few examples may be mentioned: - How to take into account atmospheric characteristics (particularly of aerosols) adapted to local and regional conditions instead of relying on default models indicating long term spatial-temporal trends that are hard to adjust to spatially restricted instantaneous observations; - How to remove noise introduced by surrounding objects. This adjacency effect phenomenon is particularly important for image resolutions smaller than 5m; - What is the effect of the viewing angle of the sensors that are increasingly aiming off-nadir, a choice imposed by the imperatives of a better temporal resolution or the acquisition of stereo pairs? - How to increase the performances of automatic multi-spectral image processing and analysis techniques in mountainous high relief area by taking into account the multiple effects of topography on the remotely sensed signal? Despite many demonstrations by researchers that information extracted from remote sensing may be altered due to the parasite factors, we are forced to note that nowadays radiometric corrections are still seldom applied, unlike geometric corrections for which commercial software possess powerful and versatile user-friendly algorithms. Radiometric correction algorithms, when available, are hard to adapt black boxes and mostly require experts to operate them. The goals we have delineated for this research are as follow: 1) Develop software to retrieve ground reflectance while taking into account the aspects mentioned earlier. This software had to be modular enough to allow improvement and adaptation to diverse remote sensing application problems; and 2) Apply this software in various context (urban, agricultural, forest) and analyse results to evaluate the accuracy gain of extracted information from remote sensing imagery transformed in ground reflectance images to demonstrate the necessity of operating in this way, whatever the type of application. During this research, we have developed a tool to retrieve ground reflectance (the new version of the REFLECT software). This software is based on the formulas (and routines) of the 6S code (Second Simulation of Satellite Signal in the Solar Spectrum) and on the dark targets method to estimated the aerosol optical thickness, representing the most difficult factor to correct. Substantial improvements have been made to the existing models. These improvements essentially concern the aerosols properties (integration of a more recent model, improvement of the dark targets selection to estimate the AOD), the adjacency effect, the adaptation to most used high resolution (Landsat TM and ETM+, all HR SPOT 1 to 5, EO-1 ALI and ASTER) and very high resolution (QuickBird et Ikonos) sensors and the correction of topographic effects with a model that separate direct and diffuse solar radiation components and the adaptation of this model to forest canopy. Validation has shown that ground reflectance estimation with REFLECT is performed with an accuracy of approximately ±0.01 in reflectance units (for in the visible, near-infrared and middle-infrared spectral bands) even for a surface with varying topography. This software has allowed demonstrating, through apparent reflectance simulations, how much parasite factors influencing numerical values of the images may alter the ground reflectance (errors ranging from 10 to 50%). REFLECT has also been used to examine the usefulness of ground reflectance instead of raw data for various common remote sensing applications in domains such as classification, change detection, agriculture and forestry. In most applications (multi-temporal change monitoring, use of vegetation indices, biophysical parameters estimation, etc.) image correction is a crucial step to obtain reliable results. From the computer environment standpoint, REFLECT is organized as a series of menus, corresponding to different steps of: input parameters introducing, gas transmittances calculation, AOD estimation, and finally image correction application, with the possibility of using the fast option witch process an image of 5000 by 5000 pixels in approximately 15 minutes. This research opens many possible pathways for improving methods and models in the realm of radiometric corrections of remotely sensed images. In particular, these include BRDF integration in the formulation, cirrus clouds correction using non selective scattering modelling and improving of the equivalent slopes topographic correction method.