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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

Espectroscopia de campo integral do Homúnculo de eta Carinae / Integral field spectroscopy of the Homunculus nebula

Teodoro, Mairan Macedo 17 June 2005 (has links)
Nesta dissertação são apresentados os resultados obtidos da espectroscopia de campo integral da nebulosa do Homúnculo. As observações foram feitas na banda J, no intervalo de 10620 Å até 12960 Å, utilizando o IFU (Integral Field Unit) do espectrógrafo CIRPASS (Cambridge Infrared Panoramic Survey Spectrograph), que possui 499 lentes hexagonais. A amostragem espacial é de 0,25"/lente e a resolução espectral, R=3200. A linha do [Fe II] λ12567 permitiu a identificação de duas estruturas no lóbulo NW que ainda não haviam sido relatadas. Através da tomografia Doppler, essas estruturas indicaram a existência de uma região de baixa densidade localizada no lóbulo NW e que não é visível nas imagens feitas na região óptica. Além disso, o Pequeno Homúnculo também foi identificado através do mapeamento das componentes e também nos mapas de velocidade da linha do [Fe II] λ12567. As regiões polares da nebulosa do Homúnculo (onde ocorre a colisão mais intensa entre o vento da fonte central e a região interna dos lóbulos) são mais opacas do que as paredes dos mesmos. Isso é verificado pela diminuição na intensidade da linha do [Fe II] λ12567 no lóbulo SE e pelo aumento desta na linha de visada do lóbulo NW. O disco equatorial foi observado nas linhas da série do H (Paβ e Paγ) e na linha do He I λ10830 como uma componente devido à emissões intrínsecas até distâncias superiores às dimensões aparentes do disco que é observado nas imagens feitas na faixa óptica. A linha do [Fe II] λ12567 também apresenta uma componente associada ao disco equatorial. Regiões de baixa densidade localizadas no toro que envolve a fonte central permitem que a radiação ultravioleta escape e excite o gás contido no disco equatorial. O melhor exemplo desse efeito foi detectado pela tomografia Doppler da linha do He I λ10830, que revelou uma componente de emissão intrínseca que atinge distâncias superiores à borda aparente do lóbulo NW do Homúnculo, e que foi completamente mapeada pela primeira vez nesta dissertação. / The Homunculus nebula was mapped using the integral field technique and the results are presented in this dissertation. The observations were obtained in the J band in the range from 10620 Å to 12960 Å using the CIRPASS's IFU, which contains 499 hexagonal lenses. The spatial sampling is 0,25"/lens and the spectral resolution, set to R=3200. The [Fe II] λ12567 line allowed the identification of two structures in the NW lobe that had not been reported yet. Doppler tomography of this structures revealed a low density region placed in the NW lobe that is not seen in the optical images. Besides, the Little Homunculus was also detected both in the mapping of components of the [Fe II] λ12567 and in its velocity maps. In the Homunculus nebula, the polar regions (where the shock between the stellar bipolar wind and the internal wall of the lobes is stronger) are more opaque than the lobe walls. This can be verified by the decrease in the intensity of the [Fe II] λ12567 in the SE lobe and the enhancement of this line emission in the NW lobe. Emissions due to the equatorial disc were detected both in the H series (Paβ and Paγ) and the He I λ10830 as an intrinsic component up to distances greater than the aparent dimensions of the disc seen in the images taken in the optical range. The [Fe II] λ12567 also presents the component due to the equatorial emission. Low density regions in the torus involving the central source allow a beam of radiation to escape to large radii and thereby excite the gas contained in the equatorial disc. The best example of this effect was detected in the Doppler tomography of the He I λ10830 line, that revealed an intrinsic emission component which reaches distances larger than the aparent boundary of the NW lobe and was firstly mapped in this dissertation.
2

Espectroscopia de campo integral do Homúnculo de eta Carinae / Integral field spectroscopy of the Homunculus nebula

Mairan Macedo Teodoro 17 June 2005 (has links)
Nesta dissertação são apresentados os resultados obtidos da espectroscopia de campo integral da nebulosa do Homúnculo. As observações foram feitas na banda J, no intervalo de 10620 Å até 12960 Å, utilizando o IFU (Integral Field Unit) do espectrógrafo CIRPASS (Cambridge Infrared Panoramic Survey Spectrograph), que possui 499 lentes hexagonais. A amostragem espacial é de 0,25"/lente e a resolução espectral, R=3200. A linha do [Fe II] λ12567 permitiu a identificação de duas estruturas no lóbulo NW que ainda não haviam sido relatadas. Através da tomografia Doppler, essas estruturas indicaram a existência de uma região de baixa densidade localizada no lóbulo NW e que não é visível nas imagens feitas na região óptica. Além disso, o Pequeno Homúnculo também foi identificado através do mapeamento das componentes e também nos mapas de velocidade da linha do [Fe II] λ12567. As regiões polares da nebulosa do Homúnculo (onde ocorre a colisão mais intensa entre o vento da fonte central e a região interna dos lóbulos) são mais opacas do que as paredes dos mesmos. Isso é verificado pela diminuição na intensidade da linha do [Fe II] λ12567 no lóbulo SE e pelo aumento desta na linha de visada do lóbulo NW. O disco equatorial foi observado nas linhas da série do H (Paβ e Paγ) e na linha do He I λ10830 como uma componente devido à emissões intrínsecas até distâncias superiores às dimensões aparentes do disco que é observado nas imagens feitas na faixa óptica. A linha do [Fe II] λ12567 também apresenta uma componente associada ao disco equatorial. Regiões de baixa densidade localizadas no toro que envolve a fonte central permitem que a radiação ultravioleta escape e excite o gás contido no disco equatorial. O melhor exemplo desse efeito foi detectado pela tomografia Doppler da linha do He I λ10830, que revelou uma componente de emissão intrínseca que atinge distâncias superiores à borda aparente do lóbulo NW do Homúnculo, e que foi completamente mapeada pela primeira vez nesta dissertação. / The Homunculus nebula was mapped using the integral field technique and the results are presented in this dissertation. The observations were obtained in the J band in the range from 10620 Å to 12960 Å using the CIRPASS's IFU, which contains 499 hexagonal lenses. The spatial sampling is 0,25"/lens and the spectral resolution, set to R=3200. The [Fe II] λ12567 line allowed the identification of two structures in the NW lobe that had not been reported yet. Doppler tomography of this structures revealed a low density region placed in the NW lobe that is not seen in the optical images. Besides, the Little Homunculus was also detected both in the mapping of components of the [Fe II] λ12567 and in its velocity maps. In the Homunculus nebula, the polar regions (where the shock between the stellar bipolar wind and the internal wall of the lobes is stronger) are more opaque than the lobe walls. This can be verified by the decrease in the intensity of the [Fe II] λ12567 in the SE lobe and the enhancement of this line emission in the NW lobe. Emissions due to the equatorial disc were detected both in the H series (Paβ and Paγ) and the He I λ10830 as an intrinsic component up to distances greater than the aparent dimensions of the disc seen in the images taken in the optical range. The [Fe II] λ12567 also presents the component due to the equatorial emission. Low density regions in the torus involving the central source allow a beam of radiation to escape to large radii and thereby excite the gas contained in the equatorial disc. The best example of this effect was detected in the Doppler tomography of the He I λ10830 line, that revealed an intrinsic emission component which reaches distances larger than the aparent boundary of the NW lobe and was firstly mapped in this dissertation.
3

Deriving Spectral Maps from JWST Data : A Study of Enceladus’ Plumes / Avledning av spektrala kartor från JWST-data : En studie av Enceladus’ plymer

Weissenböck, Stephan January 2023 (has links)
This study investigates the presence of water vapor plumes in the region south of Enceladus, a moon in the Saturnian system, through observations conducted by the James Webb Space Telescope. Enceladus is believed to harbor a subsurface ocean or localized water reservoir that gives rise to water geysers, expelling vapor into its tenuous atmosphere and outer space. On the 9th of November 2022, the James Webb Space Telescope made its first observations of the satellite using its Near-Infrared Spectrograph. The instrument's high sensitivity and spectral resolution offer the potential to measure these Enceladus' water vapor plumes, providing an opportunity to study this feature from a telescope located near Earth. However, it remains uncertain whether the obtained results are consistent with previous missions or if the instrument is even capable of conducting detailed examinations of the plumes. Hence, the primary objective of this research is to gain insights into the methodology of conducting scientific investigations of Enceladus and to understand the available data. More specifically, the aim is to verify the presence of the moon's water vapor plumes through a comprehensive analysis of the obtained data. The approach involves deriving spectral maps and extracting residual spectra that are used for comparisons with a reference spectrum entailing known water vapor emission features. The results reveal distinct emission peaks in the extracted spectra that closely resemble the features of water vapor. Additionally, the calculated column density of 6.25 - 8.25E+14 cm-2 over a region of 8.16E+07 km2 closely aligns with observations from the Herschel Space Observatory and Cassini mission. This outcome strongly supports the hypothesis that water vapor plumes are present in the area south of Enceladus, verifying the feasibility of using the James Webb Space Telescope for detecting and studying the characteristics of Enceladus' plumes. / Denna studie utforskar Enceladus' vattenplymer, en måne i Saturnussystemet, genom observationer utförda av James Webb Space Telescope. Det antas att Enceladus har en underjordisk ocean eller en lokaliserad vattenreservoar som ger upphov till vattengejsrar som sprutar ut ånga i dess tunna atmosfär och rymden. Den 9:e november 2022 genomförde James Webb-rymdteleskopet sina första observationer av satelliten med hjälp av sin nära-infraröda spektrograf. Instrumentets höga känslighet och spektrala upplösning erbjuder möjligheten att mäta Enceladus vattenplymer och därigenom möjliggöra studier av denna egenskap från ett teleskop beläget nära jorden. Det är emellertid fortfarande osäkert om de erhållna resultaten är förenliga med tidigare uppdrag eller om instrumentet ens är kapabelt att genomföra detaljerade undersökningar av plymer. Det primära syftet med denna forskning är att få insikt i metodologin för att utföra vetenskapliga undersökningar av Enceladus och att förstå den tillgängliga datan. Mer specifikt är målet att verifiera närvaron av vattenånga i månens plymer genom en omfattande analys av den insamlade datan. Metoden innefattar framställning av spektrala kartor och extrahering av restspektra. Därefter görs jämförelser mellan de extraherade spektrana och ett referensspektrum med kända emissionslinjer för vattenånga. Resultaten visar tydliga emissionspektrum i de extraherade spektrana som starkt liknar egenskaperna hos vattenånga. Dessutom stämmer den beräknade kolumn densiteten på 6.25 - 8.25E+14 cm-2 över ett område på 8,16E+07 km2 väl överens med observationer från Herschel Space Observatory och Cassini-uppdraget. Denna slutsats stöder starkt hypotesen att vattenånga finns i Enceladus' plymer och bekräftar möjligheten att använda James Webb Space Telescope för att detektera och studera egenskaperna hos Enceladus' plymer.
4

Arborização na cidade de Campinas/SP- percepção e conforto / Street trees in the city of Campinas/SP - comfort and perception

Dobbert, Léa Yamaguchi 13 February 2015 (has links)
A influência benéfica de áreas verdes no conforto humano em áreas urbanas tem sido reconhecida por estudos de diferentes campos do conhecimento. Áreas verdes e arborização bem planejada constituem importantes recursos para melhorar a qualidade do ambiente ao promover bem-estar físico e mental aos seus usuários. Avaliar o grau de interferência proporcionado pela arborização no conforto térmico e bem-estar da população foi o objetivo principal do presente estudo. O índice de floresta urbana (IFU) avaliou a interferência da quantidade de cobertura arbórea em quatro áreas da cidade de Campinas/SP/Brasil em relação às condições de conforto térmico. Para tanto, foram utilizados índices de avaliação de conforto térmico (PMV Predicted Mean Vote e PET- Physiologically Equivalent Temperature) obtidos por meio do modelo Ray Man Pro.Questionários aplicados aos usuários das áreas de estudo possibilitaram verificar se os resultados obtidos por meio dos índices PMV e PET correspondiam à real sensação de conforto térmico relatada pelos entrevistados.Simulações com o uso do programa ENVI-met v. 3.1 foram realizadas a fim de observar as interferências microclimáticas causadas pela inserção de vegetação no meio urbano. A percepção do usuário das áreas de estudo em relação à arborização urbana também foi identificada por meio de questionários. Essa pesquisa permitirá no futuro, a partir dos resultados levantados, construir um instrumento para ser incorporado no plano diretor de arborização urbana, possibilitando urbanistas e profissionais, que atuam de forma direta ou indireta no planejamento das cidades, inspecionar e analisar o conforto térmico e a qualidade de vida no meio urbano, tendo em vista a valorização e adequação da arborização viária em seus projetos. / The benefits of green urban area on human comfort have been recognized by studies performed in different knowledge fields. Green areas and urban forest planning are important tool to improve the quality of the urban environment by promoting physical and mental wellbeing to its users. The main goal of the present study is to assess the interference promoted by green areas in the welfare and thermal comfort of the urban population. The Urban Forest Index (IFU) evaluated the interference of the amount of trees in four areas of the city of Campinas, in the state of São Paulo, Brazil in relation to the conditions for thermal comfort. For this purpose, comfort indices have been used for evaluating thermal comfort (PMV-Predicted Mean Vote and PET-Physiologically Equivalent Temperature), obtained by the RayMan model. Questionnaires applied to the users on these study areas aimed to verify if the results of PET and PMV indices corresponded to the thermal sensation by respondents. Simulations using the ENVI-met program v 3.1 were conducted to observe the interference on microclimate due to the presence of vegetation in the urban environment. Questionnaires were also used to assess the perception of users on urban street trees. In the future, results obtained in this study will allow the building of an instrument, which could be included in the urban forest master plan. As a result, urban planners and other professionals who work directly or indirectly in the planning of cities will be able to inspect and evaluate the thermal comfort and the welfare of their citizens, considering the recovery and suitability of urban street trees in their projects.
5

Relação do conforto humano com métricas de cobertura arbórea / Relation of human comfort with tree cover

Oliva, Gustavo Torquatro 20 January 2017 (has links)
A influência benéfica de áreas verdes no conforto humano em áreas urbanas tem sido reconhecida por estudos de diferentes campos do conhecimento. A fim de verificar a relação existente do conforto humano com métricas de cobertura arbórea na cidade de Piracicaba/SP, foram dispostos 43 registradores higrotérmicos microprocessados durante 40 dias de coleta tanto na estação chuvosa e seca dos anos de (2015-2016), bem como uma estação meteorológica móvel, da marca Davis Vantage Vu, de modo a obter as variáveis de conforto humano relacionadas com a sensação térmica relatada pelos residentes. Para tanto, foram utilizados índices de avaliação de conforto térmico (UTCI - Universal Thermal Comfort Index) e (PET- Physiologically Equivalent Temperature) obtidos por meio do modelo RayMan Pro. Questionários aplicados aos residentes das áreas de estudo possibilitaram verificar se os resultados obtidos por meio dos índices UTCI e PET correspondiam à real sensação de conforto térmico relatada pelos entrevistados. O tecido urbano foi caracterizado por meio de classificação supervisionada realizada pelo software MultiSpec feita a partir de imagem multiespectral de alta resolução do satélite WorldView 2 no ano de 2011 para a cidade de Piracicaba/SP. Buffers (áreas de influências dos pontos analisados) de 10, 20 e 500 metros foram gerados ao redor dos pontos de estudo pelo software Quantum Gis, v. 2.4, possibilitando correlacionar a porcentagem de cobertura com os dados microclimáticos obtidos com o objetivo de se obter modelos estatísticos que conseguissem predizer o quanto de cobertura arbórea seria necessária para a diminuição de uma dada temperatura média urbana. Foram obtidos valores de Índice de Floresta Urbana (IFU) para os bairros analisados. As estações Davis Vantage Vu foi calibrada com a da ESALQ/USP no intuito de que os dados climáticos tivessem maior veracidade e estivessem condizentes com a sensação térmica relatada pelos entrevistados; além disso, foram feitos ajustes dos dias de coleta na tentativa de padronizá-los. Dentre os resultados obtidos, os valores de IFUs corresponderam aos bairros mais confortáveis. Verificou-se, também, maior correlação dos dados microclimáticos dos 43 pontos com o uso e ocupação do solo para buffers de 20 metros na estação chuvosa e buffers de 500 metros na estação seca. Sendo assim, modelos estatísticos serviram para afirmar que aproximadamente 57% (R2 = 0,57) do valor da temperatura média urbana foi explicado pela quantidade de cobertura arbórea na estação chuvosa e 60% (R2 = 0,60) do valor da temperatura média urbana foi explicado pela quantidade de cobertura arbórea na estação seca. Como resultado precípuo desta pesquisa, os modelos gerados permitiram responder uma resposta ainda inexistente: a quantidade de árvores necessária para diminuir o calor excessivo em determinada área urbana, algo altamente desejável em tempos de alterações climáticas e com cidades em crise de abastecimento de água e energia elétrica. Constatou-se, portanto, que para diminuir 1°C da temperatura média urbana é necessário acrescentar 14,31% de cobertura arbórea na estação seca e 27,70% na estação chuvosa no município de Piracicaba/SP. Como avanço nesta pesquisa e inédito para a cidade, os modelos estatísticos permitem ser adotados por outras cidades com a finalidade de proporcionar maior conforto ambiental urbano para a população e inspecionar e avaliar a situação da arborização urbana nas cidades brasileiras. / The beneficial influence of green areas on human comfort in urban areas has been recognized by studies from different fields of knowledge. In order to verify the existing relationship of human comfort with tree cover metrics in the city of Piracicaba/SP, 43 microprocessed hygrothermal registers were arranged during 40 days of collection in both rainy and dry season of the years 2015-2016, as well as a mobile weather station of the Davis Vantage Vu brand, in order to obtain the human comfort variables related to the thermal sensation reported by residents. The thermal comfort index (UTCI) and PET (Physiologically Equivalent Temperature) values were obtained using the RayMan Pro model. Questionnaires applied to the residents of the study areas made it possible to verify if the results obtained through the UTCI and PET index corresponded to the real sensation of thermal comfort reported by the interviewees. The urban area was characterized by supervised classification performed by MultiSpec software made from a high-resolution multispectral image of WorldView 2 satellite in 2011 for the city of Piracicaba/SP. Buffers (areas of influence of the analyzed points) of 10, 20 and 500 meters were generated around the points of study by Quantum Gis software, v. 2.4, making it possible to correlate the percentage of coverage with the microclimatic data, obtained with the objective of make statistical models that could predict how much tree cover would be necessary for the decrease of a given urban temperature average. Urban Forest Index (IFU) values were obtained for the neighborhoods analyzed. The Davis Vantage Vu stations were calibrated with ESALQ/USP stations in order to make the climate data more accurate and consistent with the thermal sensation reported by the interviewees; In addition, adjustments of collection days were made in an attempt to standardize them. Among the results obtained, IFU values corresponded to the most comfortable neighborhoods. It was also verified a higher correlation of the microclimatic data of the 43 points with the use and occupation of the soil for buffers of 20 meters in the rainy season and buffers of 500 meters in the dry season. Thus, statistical models served to assert that approximately 57% (R² = 0.57) of the mean urban temperature was explained by the amount of tree cover in the rainy season and 60% (R² = 0.60) of the average temperature was explained by the amount of tree cover in the dry season. As a result of this research, the models generated allowed to respond to a still non-existent response: the amount of trees needed to reduce excessive heat in a given urban area, something highly desirable in times of climate change and with cities in crisis of water and energy supply power. It was verified, therefore, that to reduce 1°C of the urban average temperature it is necessary to add 14.31% of tree cover in the dry season and 27.70% in the rainy season in the city of Piracicaba/SP. As an advance in this research and unprecedented for the city, the statistical models allow adoption by other cities with the purpose of providing greater urban environmental comfort for the population and to inspect and evaluate the situation of urban afforestation in Brazilian cities.
6

Arborização na cidade de Campinas/SP- percepção e conforto / Street trees in the city of Campinas/SP - comfort and perception

Léa Yamaguchi Dobbert 13 February 2015 (has links)
A influência benéfica de áreas verdes no conforto humano em áreas urbanas tem sido reconhecida por estudos de diferentes campos do conhecimento. Áreas verdes e arborização bem planejada constituem importantes recursos para melhorar a qualidade do ambiente ao promover bem-estar físico e mental aos seus usuários. Avaliar o grau de interferência proporcionado pela arborização no conforto térmico e bem-estar da população foi o objetivo principal do presente estudo. O índice de floresta urbana (IFU) avaliou a interferência da quantidade de cobertura arbórea em quatro áreas da cidade de Campinas/SP/Brasil em relação às condições de conforto térmico. Para tanto, foram utilizados índices de avaliação de conforto térmico (PMV Predicted Mean Vote e PET- Physiologically Equivalent Temperature) obtidos por meio do modelo Ray Man Pro.Questionários aplicados aos usuários das áreas de estudo possibilitaram verificar se os resultados obtidos por meio dos índices PMV e PET correspondiam à real sensação de conforto térmico relatada pelos entrevistados.Simulações com o uso do programa ENVI-met v. 3.1 foram realizadas a fim de observar as interferências microclimáticas causadas pela inserção de vegetação no meio urbano. A percepção do usuário das áreas de estudo em relação à arborização urbana também foi identificada por meio de questionários. Essa pesquisa permitirá no futuro, a partir dos resultados levantados, construir um instrumento para ser incorporado no plano diretor de arborização urbana, possibilitando urbanistas e profissionais, que atuam de forma direta ou indireta no planejamento das cidades, inspecionar e analisar o conforto térmico e a qualidade de vida no meio urbano, tendo em vista a valorização e adequação da arborização viária em seus projetos. / The benefits of green urban area on human comfort have been recognized by studies performed in different knowledge fields. Green areas and urban forest planning are important tool to improve the quality of the urban environment by promoting physical and mental wellbeing to its users. The main goal of the present study is to assess the interference promoted by green areas in the welfare and thermal comfort of the urban population. The Urban Forest Index (IFU) evaluated the interference of the amount of trees in four areas of the city of Campinas, in the state of São Paulo, Brazil in relation to the conditions for thermal comfort. For this purpose, comfort indices have been used for evaluating thermal comfort (PMV-Predicted Mean Vote and PET-Physiologically Equivalent Temperature), obtained by the RayMan model. Questionnaires applied to the users on these study areas aimed to verify if the results of PET and PMV indices corresponded to the thermal sensation by respondents. Simulations using the ENVI-met program v 3.1 were conducted to observe the interference on microclimate due to the presence of vegetation in the urban environment. Questionnaires were also used to assess the perception of users on urban street trees. In the future, results obtained in this study will allow the building of an instrument, which could be included in the urban forest master plan. As a result, urban planners and other professionals who work directly or indirectly in the planning of cities will be able to inspect and evaluate the thermal comfort and the welfare of their citizens, considering the recovery and suitability of urban street trees in their projects.
7

Relação do conforto humano com métricas de cobertura arbórea / Relation of human comfort with tree cover

Gustavo Torquatro Oliva 20 January 2017 (has links)
A influência benéfica de áreas verdes no conforto humano em áreas urbanas tem sido reconhecida por estudos de diferentes campos do conhecimento. A fim de verificar a relação existente do conforto humano com métricas de cobertura arbórea na cidade de Piracicaba/SP, foram dispostos 43 registradores higrotérmicos microprocessados durante 40 dias de coleta tanto na estação chuvosa e seca dos anos de (2015-2016), bem como uma estação meteorológica móvel, da marca Davis Vantage Vu, de modo a obter as variáveis de conforto humano relacionadas com a sensação térmica relatada pelos residentes. Para tanto, foram utilizados índices de avaliação de conforto térmico (UTCI - Universal Thermal Comfort Index) e (PET- Physiologically Equivalent Temperature) obtidos por meio do modelo RayMan Pro. Questionários aplicados aos residentes das áreas de estudo possibilitaram verificar se os resultados obtidos por meio dos índices UTCI e PET correspondiam à real sensação de conforto térmico relatada pelos entrevistados. O tecido urbano foi caracterizado por meio de classificação supervisionada realizada pelo software MultiSpec feita a partir de imagem multiespectral de alta resolução do satélite WorldView 2 no ano de 2011 para a cidade de Piracicaba/SP. Buffers (áreas de influências dos pontos analisados) de 10, 20 e 500 metros foram gerados ao redor dos pontos de estudo pelo software Quantum Gis, v. 2.4, possibilitando correlacionar a porcentagem de cobertura com os dados microclimáticos obtidos com o objetivo de se obter modelos estatísticos que conseguissem predizer o quanto de cobertura arbórea seria necessária para a diminuição de uma dada temperatura média urbana. Foram obtidos valores de Índice de Floresta Urbana (IFU) para os bairros analisados. As estações Davis Vantage Vu foi calibrada com a da ESALQ/USP no intuito de que os dados climáticos tivessem maior veracidade e estivessem condizentes com a sensação térmica relatada pelos entrevistados; além disso, foram feitos ajustes dos dias de coleta na tentativa de padronizá-los. Dentre os resultados obtidos, os valores de IFUs corresponderam aos bairros mais confortáveis. Verificou-se, também, maior correlação dos dados microclimáticos dos 43 pontos com o uso e ocupação do solo para buffers de 20 metros na estação chuvosa e buffers de 500 metros na estação seca. Sendo assim, modelos estatísticos serviram para afirmar que aproximadamente 57% (R2 = 0,57) do valor da temperatura média urbana foi explicado pela quantidade de cobertura arbórea na estação chuvosa e 60% (R2 = 0,60) do valor da temperatura média urbana foi explicado pela quantidade de cobertura arbórea na estação seca. Como resultado precípuo desta pesquisa, os modelos gerados permitiram responder uma resposta ainda inexistente: a quantidade de árvores necessária para diminuir o calor excessivo em determinada área urbana, algo altamente desejável em tempos de alterações climáticas e com cidades em crise de abastecimento de água e energia elétrica. Constatou-se, portanto, que para diminuir 1°C da temperatura média urbana é necessário acrescentar 14,31% de cobertura arbórea na estação seca e 27,70% na estação chuvosa no município de Piracicaba/SP. Como avanço nesta pesquisa e inédito para a cidade, os modelos estatísticos permitem ser adotados por outras cidades com a finalidade de proporcionar maior conforto ambiental urbano para a população e inspecionar e avaliar a situação da arborização urbana nas cidades brasileiras. / The beneficial influence of green areas on human comfort in urban areas has been recognized by studies from different fields of knowledge. In order to verify the existing relationship of human comfort with tree cover metrics in the city of Piracicaba/SP, 43 microprocessed hygrothermal registers were arranged during 40 days of collection in both rainy and dry season of the years 2015-2016, as well as a mobile weather station of the Davis Vantage Vu brand, in order to obtain the human comfort variables related to the thermal sensation reported by residents. The thermal comfort index (UTCI) and PET (Physiologically Equivalent Temperature) values were obtained using the RayMan Pro model. Questionnaires applied to the residents of the study areas made it possible to verify if the results obtained through the UTCI and PET index corresponded to the real sensation of thermal comfort reported by the interviewees. The urban area was characterized by supervised classification performed by MultiSpec software made from a high-resolution multispectral image of WorldView 2 satellite in 2011 for the city of Piracicaba/SP. Buffers (areas of influence of the analyzed points) of 10, 20 and 500 meters were generated around the points of study by Quantum Gis software, v. 2.4, making it possible to correlate the percentage of coverage with the microclimatic data, obtained with the objective of make statistical models that could predict how much tree cover would be necessary for the decrease of a given urban temperature average. Urban Forest Index (IFU) values were obtained for the neighborhoods analyzed. The Davis Vantage Vu stations were calibrated with ESALQ/USP stations in order to make the climate data more accurate and consistent with the thermal sensation reported by the interviewees; In addition, adjustments of collection days were made in an attempt to standardize them. Among the results obtained, IFU values corresponded to the most comfortable neighborhoods. It was also verified a higher correlation of the microclimatic data of the 43 points with the use and occupation of the soil for buffers of 20 meters in the rainy season and buffers of 500 meters in the dry season. Thus, statistical models served to assert that approximately 57% (R² = 0.57) of the mean urban temperature was explained by the amount of tree cover in the rainy season and 60% (R² = 0.60) of the average temperature was explained by the amount of tree cover in the dry season. As a result of this research, the models generated allowed to respond to a still non-existent response: the amount of trees needed to reduce excessive heat in a given urban area, something highly desirable in times of climate change and with cities in crisis of water and energy supply power. It was verified, therefore, that to reduce 1°C of the urban average temperature it is necessary to add 14.31% of tree cover in the dry season and 27.70% in the rainy season in the city of Piracicaba/SP. As an advance in this research and unprecedented for the city, the statistical models allow adoption by other cities with the purpose of providing greater urban environmental comfort for the population and to inspect and evaluate the situation of urban afforestation in Brazilian cities.
8

Développement d'un simulateur pour le X-ray integral field unit : du signal astrophysique à la performance instrumentale / Development of an End-to-End simulator for the X-ray Integral Field Unit : from the astrophysical signal to the instrument performance

Peille, Philippe 28 September 2016 (has links)
Cette thèse est consacrée au développement d'un modèle End-to-End pour le spectrocalorimètre X-IFU qui observera à partir de 2028 l'Univers en rayons X avec une précision jamais atteinte auparavant. Ce travail s'est essentiellement organisé en deux parties. J'ai dans un premier temps étudié la dynamique des parties les plus internes des binaires X de faible masse à l'aide de deux sondes particulières que sont les sursauts X et les oscillations quasi-périodiques au kHz (kHz QPOs). En me basant sur les données d'archive du satellite Rossi X-ray Timing Explorer et sur des méthodes d'analyse spécifiquement développées dans ce but, j'ai notamment pu mettre en évidence pour la première fois une réaction du premier sur le second, confirmant le lien très étroit entre ces oscillations et les parties les plus internes du système. Le temps de rétablissement du système suite aux sursauts entre également en conflit dans la plupart des cas avec l'augmentation supposée du taux d'accrétion suite à ces explosions. Au travers d'une analyse spectro-temporelle complète des deux kHz QPOs de 4U 1728-34, j'ai également pu confirmer l'incompatibilité des spectres de retard des deux QPOs qui suggère une origine différente de ces deux oscillations. L'étude de leurs spectres de covariance, obtenus pour la première fois dans cette thèse, a quant à elle mis en évidence le rôle central de la couche de Comptonisation et potentiellement celui d'une zone particulièrement compacte de la couche limite pour l'émission des QPOs. Dans le second volet de ma thèse, j'ai développé un simulateur End-to-End pour l'instrument X-IFU permettant de représenter l'ensemble du processus menant à une observation scientifique en rayons X, de l'émission des photons par une source jusqu'à leur mesure finale à bord du satellite. J'ai notamment mis en place des outils permettant la comparaison précise de plusieurs matrices de détecteurs en prenant en compte les effets de la reconstruction du signal brut issu des électroniques de lecture. Cette étude a mis en évidence l'intérêt de configurations hybrides, contenant une sous-matrice de petits pixels capables d'améliorer par un ordre de grandeur la capacité de comptage de l'instrument. Une solution alternative consisterait à défocaliser le miroir lors de l'observation de sources ponctuelles brillantes. Situées au coeur de la performance du X-IFU, j'ai également comparé de manière exhaustive différentes méthodes de reconstruction des signaux bruts issus des détecteurs X-IFU. Ceci a permis de montrer qu'à faible coût en termes de puissance de calcul embarquée, une amélioration significative de la résolution en énergie finale de l'instrument pouvait être obtenue à l'aide d'algorithmes plus sophistiqués. En tenant compte des contraintes de calibration, le candidat le plus prometteur apparaît aujourd'hui être l'analyse dans l'espace de résistance. En me servant de la caractérisation des performances des différents types de pixels, j'ai également mis en place une méthode de simulation rapide et modulable de l'ensemble de l'instrument permettant d'obtenir des observations synthétiques à long temps d'exposition de sources X très complexes, représentatives des futures capacités du X-IFU. Cet outil m'a notamment permis d'étudier la sensibilité de cet instrument aux effets de temps mort et de confusion, mais également d'estimer sa future capacité à distinguer différents régimes de turbulence dans les amas de galaxies et de mesurer leur profil d'abondance et de température. A plus long terme ce simulateur pourra servir à l'étude d'autres cas scientifiques, ainsi qu'à l'analyse d'effets à l'échelle de l'ensemble du plan de détection tels que la diaphonie entre pixels. / This thesis is dedicated to the development of an End-ta-End model for the X-IFU spectrocalorimeter scheduled for launch in 2028 on board the Athena mission and which will observe the X-ray universe with unprecedented precision. This work has been mainly organized in two parts. I studied first the dynamics of the innermost parts of low mass X-ray binaries using two specific probes of the accretion flow: type I X-ray bursts and kHz quasi-periodic oscillations (kHz QPOs). Starting from the archivai data of the Rossi X-ray Timing Explorer mission and using specific data analysis techniques, I notably highlighted for the first time a reaction of the latter to the former, confirming the tight link between this oscillation and the inner parts of the system. The measured recovery time was also found in conflict with recent claims of an enhancement of the accretion rate following these thermonuclear explosions. From the exhaustive spectral timing analysis of both kHz QPOs in 4U 1728-34, I further confirmed the inconsistancy of their lag energy spectra, pointing towards a different origin for these two oscillations. The study of their covariance spectra, obtained here for the first time, has revealed the key role of the Comptonization layer, and potentially of a more compact part of it, in the emission of the QPOs. In the second part of my thesis, I focused on the development of an End-to-:End simulator for the X-IFU capable of depicting the full process leading to an X-ray observation, from the photon emission by the astrophysical source to their on-board detection. I notably implemented tools allowing the precise comparison of different potential pixel array configurations taking into account the effects of the event reconstruction from the raw data coming from the readout electronics. This study highlighted the advantage of using hybrid arrays containing a small pixel sub-array capable of improving by an order of magnitude the count rate capability of the instrument. An alternative solution would consist in defocusing the mirror during the observation of bright point sources. Being a key component of the overall X-IFU performance, I also thoroughly compared different reconstruction methods of the pixel raw signal. This showed that with a minimal impact on the required on-board processing power, a significant improvement of the final energy resolution could be obtained from more sophisticated reconstruction methods. Taking into account the calibration constraints, the most promising candidate currently appears to be the so-called "resistance space analysis". Taking advantage of the obtained performance characterization of the different foreseen pixel types, I also developed a fast and modular simulation method of the complete instrument providing representative synthetic observations with long exposure times of complex astrophysical sources suffinguish different turbulence regimes in galaxy clusters and to measure abundance and temperature profiles. In the longer run, this simulator will be useful for the study of other scientific cases as well as the analysis of instrumental effects at the full detection plane level such as pixel crosstalk.
9

Cosmic applications of gravitational lens assisted spectroscopy (GLAS)

Thanjavur, Karunananth G. 19 November 2008 (has links)
The principal observational contribution of this thesis is an innovative technique, using spatially resolved spectroscopy of highly magnified, gravitationally lensed galaxies, to study their internal structure and kinematics at redshift, z≥1 on sub-galactic scales. The scientific objective is to measure the important, but poorly understood, role of star formation and associated feedback on galaxy evolution. With Gemini GMOS-IFU observations of CFRS03+1077, a lensed galaxy at z=2.94, we determined surface brightness and integration time requirements for spatially resolved kinematics with spectra in the visible region (< 1 micron). For reasonable exposure times the presence of a strong emission line is key, limiting the redshift range to < 1.5 for [OII]3727Å. To tackle the lack of suitable lenses for such studies, we designed a lens search algorithm suitable for multi-color photometric data (with a minimum of 2 colors). Our method uses a two-step approach, first automatically identifying galaxy clusters and groups as high likelihood lensing regions, followed by a dedicated visual search for lensed arcs in pseudo-color images of sub-regions centered on these candidates. By using the color-position clustering of elliptical galaxies in high density environments, the algorithm efficiently isolates candidates with a completeness ≥ 80% for z ≤ 0.6 in Monte-Carlo simulations. Implemented on the CFHT Legacy Survey-Wide fields with available g, r and i photometry, the present yield is 9 lenses (8 new and 1 previously known) from 104 deg². With Gemini GMOS, we confirmed two lensed galaxies with strong [OII]3727Å emission suitable for IFU spectroscopy. The follow-up of both systems, the confirmation of remaining lenses and the application of the lens detector to the remaining 91 square degrees of CFHTLS-Wide are ongoing. In a complementary project, we aim to understand non-linear structure formation within the Λ-CDM framework by characterizing the mass distributions and mass/light ratios of galaxy groups; these structures (where 60% of all galaxies reside), have masses representative of the critical break between cluster and field galaxy mass scales. We use strong gravitational lensing to constrain the mass in the inner core, with velocity dispersion measurements from MOS spectroscopy to map the mass distribution up to the scale of the virial radius. The formalism supporting this approach as well as the tools for analysis (including an efficient B-spline based method for flat fielding and sky subtraction of sky limited spectra) are presented in this thesis. The deflectors of 6 lenses in our catalog resemble galaxy groups suitable for this study. One group, for which the observations are complete, is compatible with either NFW or Hernquist profile; these results will be corroborated with observations of other candidates in forthcoming observing programs. The objective is to amalgamate our results with mass measurements from weak lensing and X-ray observations from our Strong Lensing Legacy Survey (SL2S) collaborators to build a comprehensive picture of the dark matter profile and thus constrain theoretical predictions of mass assembly in galaxy groups.
10

Les Coeurs en Contre-Rotation

Wernli, Fabien 28 November 2002 (has links) (PDF)
Les galaxies elliptiques ne sont des objets astronomiques très simples qu'en apparence: leur forme parfaitement régulière et ellipsoïdale est davantage le vestige d'une histoire tumultueuse semée d'interactions gravitationnelles avec d'autres galaxies plutôt que le signe d'un stade primitif dans leur vie. En effet, ces deux dernières décennies ont révélé la complexité de ces objets au niveau de leur cinématique interne, et surtout récemment avec le spectrographe intégral de champ SAURON qui a permis de dresser la structure bidimensionnelle de la vitesse de nombreuses galaxies elliptiques. La compréhension de la formation et de l'évolution de ces objets est un enjeu majeur de l'astrophysique contemporaine. La théorie hiérarchique de formation et d'évolution des galaxies, selon laquelle une galaxie est le résultat de nombreuses interactions et de fusions d'objets moins massifs, est à l'heure actuelle la mieux soutenue par les observations. Ainsi, elle permet de rendre compte de structures complexes telles les galaxies à coeur cinématiquement distinct, dans lesquelles on observe un brusque changement dans la courbe de rotation. Certains de ces objets montrent même une inversion dans le sens de rotation de la partie interne. De nombreuses études ont été réalisées pour comprendre les mécanismes de formation de ces coeurs, et la plupart d'entre elles semblent nécessiter l'apport d'un corps externe voire la fusion de deux galaxies. Dans ce travail nous réalisons dans un premier temps un catalogue de ces objets, afin d'en dégager les conclusions majeures. Dans un second temps nous présentons une méthode permettant d'extraire la signature orbitale de ces structures découplées en utilisant une modélisation dynamique de Schwarzschild . Nous appliquons cette méthode à trois objets dont nous disposons des données intégrales de champ, et tentons d'en extraire les principaux points communs. Finalement nous soulignons la valeur de cette méthodologie pour contraindre les modèles hiérarchiques de formation.

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