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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Les Cultures kerma : essai de classification /

Gratien, Brigitte. January 1978 (has links)
Texte remanié de--Lettres--Lille III, 1974. / Thèse soutenue sous le titre : "Essai de classification des cultures kerma" Bibliogr. p. 333-348. Index.
2

Room radiation dose coefficients for external exposure

Finklea, Lauren 21 September 2015 (has links)
In instances where a building room is radiologically contaminated, dose rate coefficients are needed to estimate the dose rate to the occupants. One’s position in the room, whether in the center of the room or the corner, could have an effect on dose rate. The Environmental Protection Agency (EPA) published in Federal Guidance Report 12 (EPA 1993) dose rate coefficients for idealized exposure geometries, including exposure to radionuclides distributed infinitely in various thicknesses of soil. The dimensions of the exposure plane were taken to be infinite in extent. Due to this assumption, using the Federal Guidance Report coefficients could lead to an incorrect estimate of dose rate inside a contaminated room. In order to apply the published coefficients for a structure, we developed Room Ratios using MCNP5 to compare air kerma rate of various room sizes and multiple building materials to the published infinite air kerma rate taking into account several receptor positions. Room Ratio values will be used for preliminary remediation risk assessment for environmental radionuclide clean up and be integrated into existing online tools and databases (epa-bprg.ornl.gov). The incorporation of ratios into these tools will update dose coefficients that previously accounted only for surface contamination (Eckerman 2010). Additionally, Room Ratios will allow Federal Guidance Report 12 dose coefficients application to customizable building materials and thickness.
3

Desenvolvimento de uma metodologia de avaliação de medidores portáteis de radiação em altas taxas de kerma no ar / Development of a methodology of portable radiation meters at high rates of air

Damatto, Willian Behling 18 November 2015 (has links)
Uma série de testes foi aplicada a medidores portáteis de radiação ionizante para altas taxas de kerma no ar, especificamente medidores do tipo teletector. Estes detectores são do tipo Geiger Müller e são utilizados em rotinas de proteção radiológica em aceleradores, reatores, fontes de alta atividade e ainda em situações de emergência no Brasil, assim como em outros países. Também são encaminhados para calibração no Instituto de Pesquisa Energéticas e Nucleares (IPEN) e foram analisados para estabelecer parâmetros de comportamento destes detectores, especificando as suas sensibilidades e suas características operacionais. Foram realizados testes de variação da leitura dos equipamentos com a tensão da bateria, efeito de geotropismo, dependência energética, dependência angular. Com este testes foi possível determinar as características mais comuns e importantes destes equipamentos permitindo a elaboração de um programa de controle de qualidade. Foram calibrados 17 teletectors durante este trabalho e destes, 10 foram testados. Os testes foram realizados para caracterizar o sis tema gama de irradiação (dosimetria de feixe de radiação) que possui maior atividade e permite testes em medidores do tipo teletectors em uma maior faixa de medição. Desse modo foi feito o aperfeiçoamento do programa de controle de qualidade de medidores portáteis de radiação ionizante para altas taxas de kerma no ar no LCI, oque beneficiou os usuários deste tipo de equipamento, e ainda com medições e calibrações mais consistentes e com melhor controle de qualidade dos processos. / A series of tests was applied to portable survey meters for high rates of kerma in the air, specifically meters type teletector. These detectors are the Geiger- Müller type and are used in radioprotection routines in accelerators, nuclear reactors, irradiators systems with high activity sources and even in emergency situations in Brazil, as in other countries. They are also sent for calibration at the Instruments Calibration Laboratory (LCI) at the Institute of Energy and Nuclear Research (IPEN) and were analyzed to establish behavior parameters of these detectors, specifying their sensitivities and their operational characteristics. The reading variation tests were performed with the equipment battery voltage variation, geotropism effect, energy dependence, angular dependence; with these tests was possible to determine the most common and important features of these devices, allowing the development of a quality control program. In this work 17 teletectors were analyzed and ten detectors tested. The tests were performed to characterize the gamma irradiator system (dosimetry of dosimetry beam) which has higher activity and allows test in meters type teletector in a higher measuring range. Thus, it was made the improvement of the quality control program of portable survey meters of high rates of kerma in the air in the LCI, benefiting the users of such equipment and with measurements and calibrations more consistent and better quality control processes.
4

Desenvolvimento de uma metodologia de avaliação de medidores portáteis de radiação em altas taxas de kerma no ar / Development of a methodology of portable radiation meters at high rates of air

Willian Behling Damatto 18 November 2015 (has links)
Uma série de testes foi aplicada a medidores portáteis de radiação ionizante para altas taxas de kerma no ar, especificamente medidores do tipo teletector. Estes detectores são do tipo Geiger Müller e são utilizados em rotinas de proteção radiológica em aceleradores, reatores, fontes de alta atividade e ainda em situações de emergência no Brasil, assim como em outros países. Também são encaminhados para calibração no Instituto de Pesquisa Energéticas e Nucleares (IPEN) e foram analisados para estabelecer parâmetros de comportamento destes detectores, especificando as suas sensibilidades e suas características operacionais. Foram realizados testes de variação da leitura dos equipamentos com a tensão da bateria, efeito de geotropismo, dependência energética, dependência angular. Com este testes foi possível determinar as características mais comuns e importantes destes equipamentos permitindo a elaboração de um programa de controle de qualidade. Foram calibrados 17 teletectors durante este trabalho e destes, 10 foram testados. Os testes foram realizados para caracterizar o sis tema gama de irradiação (dosimetria de feixe de radiação) que possui maior atividade e permite testes em medidores do tipo teletectors em uma maior faixa de medição. Desse modo foi feito o aperfeiçoamento do programa de controle de qualidade de medidores portáteis de radiação ionizante para altas taxas de kerma no ar no LCI, oque beneficiou os usuários deste tipo de equipamento, e ainda com medições e calibrações mais consistentes e com melhor controle de qualidade dos processos. / A series of tests was applied to portable survey meters for high rates of kerma in the air, specifically meters type teletector. These detectors are the Geiger- Müller type and are used in radioprotection routines in accelerators, nuclear reactors, irradiators systems with high activity sources and even in emergency situations in Brazil, as in other countries. They are also sent for calibration at the Instruments Calibration Laboratory (LCI) at the Institute of Energy and Nuclear Research (IPEN) and were analyzed to establish behavior parameters of these detectors, specifying their sensitivities and their operational characteristics. The reading variation tests were performed with the equipment battery voltage variation, geotropism effect, energy dependence, angular dependence; with these tests was possible to determine the most common and important features of these devices, allowing the development of a quality control program. In this work 17 teletectors were analyzed and ten detectors tested. The tests were performed to characterize the gamma irradiator system (dosimetry of dosimetry beam) which has higher activity and allows test in meters type teletector in a higher measuring range. Thus, it was made the improvement of the quality control program of portable survey meters of high rates of kerma in the air in the LCI, benefiting the users of such equipment and with measurements and calibrations more consistent and better quality control processes.
5

Kerma no ar com base no índice de exposição para radiografia digital / Air kerma based on the exposure index for digital radiography

Leite, Marina Silveira 26 November 2012 (has links)
Os receptores de imagem radiográfica digitais estão gradualmente substituindo os sistemas tela-filme em radiodiagnóstico. Atualmente a radiografia computadori- zada (CR - Computed Radiography) é a modalidade digital mais comum em muitos serviços de radiodiagnostico. E baseada na utilização de fósforos foto estimuláveis, que também são conhecidos como fósforo de armazenamento. Quando sistemas tela-filme são utilizados como receptores de imagem, uma dose de radiação inadvertidamente alta no paciente irá resultar em um filme escuro, que fornece feedback imediato para o técnico em radiologia quanto aos fatores de técnica utilizados e a dose relativa. No entanto, quando receptores de imagem digitais são usados, uma dose alta no paciente pode produzir imagens excelentes o que resulta em uma tendência de se utilizar doses mais elevadas do que o necessário. A adequada justificação e otimização dos procedimentos exige o conhecimento dos valores típicos de dose em pacientes em um determinado serviço de radiodiagnóstico. O termo índice de exposição refere-se à dose absorvida na placa fósforo. Após a leitura da imagem com um sistema de laser o histograma dos sinais é computado e o índice de exposição é determinado com base nos valores dos pixels (picture elements) usando uma relação logarítmica. Os fabricantes dos sistemas de CR oferecem os índices de exposição como um salvaguarda contra doses altas, mas a base para os valores recomendados não é clara. Além disso, os índices de exposição não estão diretamente relacionados com a dose no paciente. O objetivo deste trabalho foi estabelecer um método indireto para calcular os valores de dose de entrada em pacientes submetidos a exames diagnósticos em sistemas de raios X com CR com base no índice de exposição. / The receptors of digital radiography image are gradually substituting the screen-film systems in radiodiagnostic. Currently, computed radiography is the most common method in many radiography services. It is based in the application of photostimulable phosphorus, that are also known as phosphorus storage. When screen-film systems are utilized as image receptors, an inadvertently high dose of radiation in the patient will result in a dark film screen, that inputs immediate feedback to the radiology technician as to the technical factors utilized and the relative dose. However, when digital image receptors are used, a high dose in the patient can produce excelent images which re-sult in a tendency of using higher doses than necessary. The adequate extenuation and optimization of the procedures demand the knowledge of the characteristic dose values in patients in a determined radiodiagnostic service. The term exposure index refers to the absorbed dose in the phosphorus plate. Following the image reading with a laser system the histogram of signs is computed and the exposure index is determi-ned in the basis of picture elements using a logarithmic relationship. The manufacturer of the systems of pixels offer the exposure indexes as a safeguard against high doses, but the basis for the recommended values are not clear. Moreover, the exposure indexes are not directly related to the dose in patients. The aim of this work was to establish an indirect method to estimate the values of entrance doses in patients who have undergone diagnostic exams in X ray systems with computed radiography based on exposure indexes. The values of entrance doses obtained were compared with the values also obtained indirectly based in the measurements of the X ray tubes output.
6

Kerma no ar com base no índice de exposição para radiografia digital / Air kerma based on the exposure index for digital radiography

Marina Silveira Leite 26 November 2012 (has links)
Os receptores de imagem radiográfica digitais estão gradualmente substituindo os sistemas tela-filme em radiodiagnóstico. Atualmente a radiografia computadori- zada (CR - Computed Radiography) é a modalidade digital mais comum em muitos serviços de radiodiagnostico. E baseada na utilização de fósforos foto estimuláveis, que também são conhecidos como fósforo de armazenamento. Quando sistemas tela-filme são utilizados como receptores de imagem, uma dose de radiação inadvertidamente alta no paciente irá resultar em um filme escuro, que fornece feedback imediato para o técnico em radiologia quanto aos fatores de técnica utilizados e a dose relativa. No entanto, quando receptores de imagem digitais são usados, uma dose alta no paciente pode produzir imagens excelentes o que resulta em uma tendência de se utilizar doses mais elevadas do que o necessário. A adequada justificação e otimização dos procedimentos exige o conhecimento dos valores típicos de dose em pacientes em um determinado serviço de radiodiagnóstico. O termo índice de exposição refere-se à dose absorvida na placa fósforo. Após a leitura da imagem com um sistema de laser o histograma dos sinais é computado e o índice de exposição é determinado com base nos valores dos pixels (picture elements) usando uma relação logarítmica. Os fabricantes dos sistemas de CR oferecem os índices de exposição como um salvaguarda contra doses altas, mas a base para os valores recomendados não é clara. Além disso, os índices de exposição não estão diretamente relacionados com a dose no paciente. O objetivo deste trabalho foi estabelecer um método indireto para calcular os valores de dose de entrada em pacientes submetidos a exames diagnósticos em sistemas de raios X com CR com base no índice de exposição. / The receptors of digital radiography image are gradually substituting the screen-film systems in radiodiagnostic. Currently, computed radiography is the most common method in many radiography services. It is based in the application of photostimulable phosphorus, that are also known as phosphorus storage. When screen-film systems are utilized as image receptors, an inadvertently high dose of radiation in the patient will result in a dark film screen, that inputs immediate feedback to the radiology technician as to the technical factors utilized and the relative dose. However, when digital image receptors are used, a high dose in the patient can produce excelent images which re-sult in a tendency of using higher doses than necessary. The adequate extenuation and optimization of the procedures demand the knowledge of the characteristic dose values in patients in a determined radiodiagnostic service. The term exposure index refers to the absorbed dose in the phosphorus plate. Following the image reading with a laser system the histogram of signs is computed and the exposure index is determi-ned in the basis of picture elements using a logarithmic relationship. The manufacturer of the systems of pixels offer the exposure indexes as a safeguard against high doses, but the basis for the recommended values are not clear. Moreover, the exposure indexes are not directly related to the dose in patients. The aim of this work was to establish an indirect method to estimate the values of entrance doses in patients who have undergone diagnostic exams in X ray systems with computed radiography based on exposure indexes. The values of entrance doses obtained were compared with the values also obtained indirectly based in the measurements of the X ray tubes output.
7

Égyptiens et Nubiens à Kerma : la céramique de Doukki Gel (Soudan) au Nouvel Empire / Egyptians and Nubians in Kerma : the Pottery from Dokki Gel (Sudan) during the New Kingdom

Ruffieux, Philippe 22 October 2018 (has links)
Les temples égyptiens de Doukki Gel, à Kerma (Soudan), ont été bâtis sous le règne de Thoutmosis Ier, au centre d’un ensemble religieux et cérémoniel du Kerma Classique. Les fouilles du site ont livré de grandes quantités de céramiques, dont l’étude constitue la matière de cette thèse. De concert avec l’analyse stratigraphique et l’épigraphie, l’approche typologique de la poterie, premier axe de recherche, a contribué à la datation de nombreux contextes archéologiques. Par ailleurs, six phases de développement ont été mises en évidence, au sein du corpus céramique du Nouvel Empire, depuis la fin du Kerma Classique. Le second axe de recherche, l’analyse technologique, basée principalement sur le système dit « de Vienne », a permis de définir des variantes locales des pâtes de tradition égyptienne, alors que la tradition Kerma a fait l’objet d’un système de classification particulier. L’étude indique que la grande majorité du matériel des deux traditions était fabriqué localement, et révèle des influences réciproques entre Nubiens et Égyptiens, dues à la situation singulière de ce site. Une analyse des données quantitatives du matériel récolté dans différents secteurs permet en outre de proposer une identification fonctionnelle des espaces et de la circulation des denrées dans le cadre des activités cultuelles, au sein de trois organisations architecturales successives. Ces données suggèrent également une longue survivance de la tradition Kerma déclinante, à l’échelle locale ou régionale, pendant le Nouvel Empire. / The Egyptian temples at Dokki Gel, Kerma (Sudan), were built during the reign of Thutmose I, in the heart of a Classic Kerma religious and ceremonial compound. The excavations of the site have yielded a huge number of potsherds whose study constitute the focus of this thesis. The typological approach, combined with stratigraphic analysis and epigraphy, has allowed the dating of many archaeological contexts. Moreover, six development phases within the New Kingdom ceramic corpus were identified, starting at the end of the Classic Kerma. The technological analysis, relying mainly on the so-called « Vienna System », led to the definition of local variants of egyptian pottery fabrics, whereas the Kerma material had to be classified separately. A large majority of pottery from both traditions was most likely produced locally and shows signs of mutual influences between Nubians and Egyptians. Analysis of the quantitative data of ceramic assemblages gathered from various sectors brings us to an identification of probable space functions, and movement of commodities within the framework of temple cult ativities and according to three successive architectural organizations. They also suggest a long period of survival of the declining Kerma pottery tradition, during the New Kingdom.
8

Behavioral Reconstruction of the Kerma Era Nubians

Martin, D.C. 01 December 2015 (has links)
Cultural adaptations to environment can result in certain biological changes in individuals (Kennedy, 1989; Jurmain, 1999). Some of these changes can affect the human skeleton and leave markers pointing to patterns of habitual behavior or general level of workload stress placed on the body. This study assesses the variation in workload caused by environmental and cultural differences of three contemporaneous Nubian groups of the Kerma era (2,500-1,500BC) in ancient Nubia. The skeletal samples used here are from three contemporaneous ancient Nubian groups who lived during this period. The Kerma Collection represents a population from the urban capital city of Kerma in Upper Nubia (1,750-1,500BC; n=216), the collection of the Northern Dongola Reach Survey (NDRS) represents a rural population located 70km south of the Kerma city in Upper Nubia (2,500-1,750BC; n=48), and the C-Group collection represents a subsistence based society from the area of Lower Nubia (2,000-1,600BC; n=109). The rural and urban groups were located in the fertile area of Sudan known as the Dongola Reach and the subsistence based society occupied the more rugged, desert-like terrain outside of the Dongola Reach. Behavioral reconstruction markers entheseal changes (EC), workload trauma, and degenerative joint disease (DJD) were employed in order to attain broader answers of how Homo sapiens from the same civilization cope with varying environments. Results suggest that the subsistence based population (C-Group) experienced the least amount of workload stress, suggesting increase in workload with an increase in agricultural intensity/social complexity, as both the urban and rural populations had much more intensive agriculture and were more socially complex than the subsistence based population. This increase in workload with the advent of agriculture (Cohen and Armelagos, 1984; Goodman et al., 1984; Larsen, 1995) and with increase in social complexity (Zabecki, 2009) has been suggested in prior studies with other populations and this is seen here. Furthermore, though sex differences concerning pattern of behavior are clearer in the C-Group suggesting fewer habitual activities due to a less complex society (as suggested by Petersen, 1998; Eshed et al., 2004), similar behavior differences between sexes were still somewhat visible in the urban and rural populations. This suggests that some cultural traits remain constant in the Nubian culture despite environment or level of social complexity. The Kerma city and NDRS collections are, in general, highly stressed when compared to the C-Group or contemporaneous populations, irrespective of which marker is assessed. This may be due to the intensive agriculture practiced or the threat of attack from other populations forcing strenuous construction and fortification efforts of settlements. Juvenile remains, which are traditionally excluded from behavior studies, displayed lesions on several areas of the skeleton which may suggest heavy workload. This study builds on previous information known about the people of the Kerma era and gains a clearer perspective of how these populations lived their lives from day to day. These data can be used to continue investigation into ways in which environment and culture affect human biology and, in turn, the human skeleton.
9

Desenvolvimento de uma metodologia de calibração e testes de medidores de produto Kerma-Área / Development of a calibration methodology and tests of kerma area product meters

Costa, Nathalia Almeida 20 June 2013 (has links)
A grandeza produto kerma-área (PKA) é importante para estabelecer níveis de referência em exames de radiologia diagnóstica. Essa grandeza pode ser obtida por meio de medidores do PKA. O uso desses medidores é fundamental para avaliar a dose de radiação em procedimentos radiológicos, além de ser um bom indicador para que os limites de dose na pele do paciente não sejam excedidos. Algumas vezes, esses medidores vêm acoplados a equipamentos de radiação X, o que dificulta sua calibração. Neste trabalho foi desenvolvida uma metodologia de calibração de medidores do PKA. O instrumento utilizado para este fim foi o Patient Dose Calibrator (PDC). Ele foi desenvolvido para ser utilizado como referência na verificação da calibração de medidores do PKA e kerma no ar usados na dosimetria de pacientes e para verificação da consistência e do comportamento de sistemas de controle de exposição automáticos. Por se tratar de um equipamento novo, que, no Brasil, ainda não é utilizado como equipamento de referência para calibração, foi realizado, também o controle de qualidade deste equipamento, com testes de caracterização, a calibração e a avaliação da dependência energética. Após os testes, ficou provado que o PDC pode ser utilizado como instrumento de referência para a calibração a ser realizada in situ, de forma que as características de cada equipamento de radiação X onde os medidores do PKA são utilizados sejam consideradas. A calibração foi, então, realizada com medidores do PKA portáteis e em um equipamento de radiologia intervencionista que possui um medidor do PKA acoplado. Os resultados foram bons e ficou provada a necessidade de calibração desses medidores e a importância da calibração in situ com um medidor de referência. / The quantity kerma area product (PKA) is important to establish reference levels in diagnostic radiology exams. This quantity can be obtained using a PKA meter. The use of such meters is essential to evaluate the radiation dose in radiological procedures and is a good indicator to make sure that the dose limit to the patient\'s skin doesnt exceed. Sometimes, these meters come fixed to X radiation equipment, which makes its calibration difficult. In this work, it was developed a methodology for calibration of PKA meters. The instrument used for this purpose was the Patient Dose Calibrator (PDC). It was developed to be used as a reference to check the calibration of PKA and air kerma meters that are used for dosimetry in patients and to verify the consistency and behavior of systems of automatic exposure control. Because it is a new equipment, which, in Brazil, is not yet used as reference equipment for calibration, it was also performed the quality control of this equipment with characterization tests, the calibration and an evaluation of the energy dependence. After the tests, it was proved that the PDC can be used as a reference instrument and that the calibration must be performed in situ, so that the characteristics of each X-ray equipment, where the PKA meters are used, are considered. The calibration was then performed with portable PKA meters and in an interventional radiology equipment that has a PKA meter fixed. The results were good and it was proved the need for calibration of these meters and the importance of in situ calibration with a reference meter.
10

Caracterização de uma câmara de ionização ar-livre em feixes diretos de raios X utilizados em mamografia / Characterization of a free-air ionization chamber in direct X-ray beams as used in mammography

Lima, Mateus Hilário de 24 February 2014 (has links)
Neste trabalho foram realizados testes de estabilidade e de caracterização de uma câmara de ionização de ar-livre com cilindros concêntricos da marca Victoreen, modelo 481. Os testes foram feitos utilizando feixes diretos de mamografia como uma contribuição para a implantação desta câmara como sistema padrão primário para a grandeza kerma no ar. Os testes de caracterização realizados foram: curva de saturação, eficiência de coleção de íons, efeito de polaridade, linearidade da resposta com a taxa de kerma no ar e linearidade da resposta com a variação volumétrica. O teste de eficiência de coleção de íons possibilitou a determinação do fator de correção para recombinação iônica. A maioria dos testes realizados esteve em conformidade com os limites estabelecidos por normas internacionais. Foram obtidos os fatores de correção para atenuação de fótons no ar para as qualidades de mamografia com filtros de alumínio e molibdênio. Foram determinados também os fatores de correção para transmissão e espalhamento de fótons nas bordas do diafragma para as qualidades de mamografia com filtro de alumínio e para a qualidade padrão de mamografia com filtro de molibdênio. / At this work stability and characterization tests were undertaken on a Victoreen free-air ionization chamber, model 481. The tests were realized using direct X-ray beams as a contribuition for its establishment as a primary standard system of the quantity air kerma. The characterization tests were: saturation curve, ion collection efficiency, polarity effect, response linearity with the air kerma rate and response linearity with the chamber volume variation. The ion collection efficiency allowed the determination of the ion recombination factor. Most of the test results showed agreement with the limits established by international standards. Furthermore, the air attenuation factors for the mammography beams with aluminum and molybdenum filters were obtained. The factors for photon transmission and scattering at the diaphragm edges were also determined for mammography beams with aluminum filter and for the standard beam with molybdenum filter.

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