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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.
91

The Thermodynamics of Planetary Engineering on the Planet Mars

Barsoum, Christopher 01 May 2014 (has links)
Mars is a potentially habitable planet given the appropriate planetary engineering efforts. In order to create a habitable environment, the planet must be terraformed, creating quasi-Earth conditions. Benchmarks for minimum acceptable survivable human conditions were set by observing atmospheric pressures and temperatures here on Earth that humans are known to exist in. By observing a positive feedback reaction, it is shown how the sublimation of the volatile southern polar ice cap on Mars can increase global temperatures and pressures to the benchmarks set for minimum acceptable survivable human conditions. Given the degree of uncertainty, utilization of pressure scale heights and the Martin extreme terrain were used to show how less than desirable conditions can still produce results where these benchmarks can be met. Methods for obtaining enough energy to sublimate the southern polar ice cap were reviewed in detail. A new method of using dark, carbonaceous Martian moon material to alter the overall average albedo of the polar ice cap is proposed. Such a method would increase Martian energy efficiency. It is shown that by covering roughly 10% of the Martian polar ice cap with dark carbonaceous material, this required energy can be obtained. Overall contributions include utilization of pressure scale heights at various suggested settlement sites, as well as polar albedo altering as a method of planetary engineering. This project serves as a foundational work for long term solar system exploration and settlement.
92

Comparative study of albedo and Ndvi. : Based on a vertical Agrivoltaic system and a reference control plot.

Aryal, Prasamsa January 2024 (has links)
Agrivoltaic system combines solar energy and agriculture which is an effective way to utilize the lands full potential. Crops can be grown between vertical panels or under tilted panels among other designs. Combining solar panels and agriculture leads to optimization of space. This degree project evaluates a comparison of several parameters measured both in a vertical agrivoltaic system and a reference control plot located in Kärrbo Prästgård, Västerås, Sweden. Specifically, the correlation between the ground albedo and normalized difference vegetation index (NDVI) under the two treatments are investigated. Correlations between the albedo and the NDVI against different weather parameters are also explored. Linear regression models are developed separately for the albedo and NDVI with the most correlated parameters. In addition, because the albedo in the reference is not the same as the albedo in the agrivoltaic system, a linear regression model linking the albedo of the agrivoltaic system, and the albedo of the reference system is further developed. With this latter model, power production from the vertical agrivoltaic system is simulated under different albedo considerations: using measured albedo from the agrivoltaic system, using predicted albedo from the linear regression model, and using measured albedo from the reference system. These power estimations are then compared to the real power production from the agrivoltaic system. The study employs MATLAB for data analysis, models development and power production simulations.   The study compared the correlation between ground albedo and NDVI in an agrivoltaic system and a control plot. The albedo model revealed that the reference system could explain 87% of the albedo variance in the agrivoltaic system, but the NDVI model showed that the reference system could only account for 39.6% of the variation in the agrivoltaic system. Furthermore, for the power production comparison, using the actual measured albedo in the agrivoltaic showed the most accurate power, employing predicted albedo through the linear regression model showed the second highest and using the albedo measured in the reference showed the least accurate.
93

Investigation of Optical Properties of Size-Selected Black Carbon Under Controlled Laboratory Conditions

Lei, Ziying January 2016 (has links)
No description available.
94

Examination of Sensitivity of Land Use Parameters and Population on the Performance of the AERMOD Model for an Urban Area

Bhardwaj, Kanwar S. January 2005 (has links)
No description available.
95

Solar Irradiance Assessment in Agrivoltaic Systems : Understanding Photosynthetically Active Radiation Separation Models and Dynamic Crop Albedo Effect in Agrivoltaic Systems Modelling

Ma Lu, Silvia January 2024 (has links)
Agrivoltaics, also referred as agrivoltaic systems, present an appealing solution, owing to its dual land use and integrated food-energy system, for the shift to renewable energy. However, it raises concerns about the complex synergies and trade-offs between crop growth and solar photovoltaic panels. Crops grown under open-field traditional agriculture receive uniformly distributed Sun irradiance, whereas agrivoltaics introduces variable shadowing, which interferes with the homogeneity of light collected by crops.  Agrivoltaics emphasises the significance of the diffuse irradiance component during shading conditions when direct irradiance is blocked by solar panels. Decomposition models are essential for estimating the diffuse light component from the global one. This thesis conducts a benchmarking investigation of state-of-the-art solar irradiance decomposition models to identify the most suitable ones for decomposing photosynthetically active radiation in specific Swedish sites. The results lead to a novel separation model that outperforms the top models revealed in the benchmarking analysis. Various scenarios common in agrivoltaic sites are used to test the applicability of the model and guide model selection based on available data.  In agrivoltaic systems, where solar panels disrupt incoming sunlight to crops, the crop reflectivity or albedo influences solar panels, particularly those with bifacial solar cells. This thesis further investigates how ground-reflected irradiance components affect the front and rear sides of bifacial system designs under varied ground albedo circumstances. Using Agri-OptiCE®, this research examines how albedo data quality affects bifacial systems. The findings contribute to improve the precision of plane-of-array irradiance and power output estimations, hence aiding the practical implementation of agrivoltaic systems across the globe.
96

Características hidrometeorológicas em uma floresta de Pinus elliotii no Cerrado / Hydrometeorologycal characteristics of the Pinus elliotii forest in Cerrado

Pereira Neto, Sílvio Dias 28 March 2003 (has links)
O governo do Estado de São Paulo, na década de 60, realizou um programa de introdução de florestas do gênero Pinus para consolidar esta cultura no estado. Algumas destas florestas foram implantadas em áreas do Cerrado, que estavam degradadas devido à utilização para pastagens. Com a intenção de contribuir para um melhor entendimento das características hidrometeorológicas em uma floresta de P. elliotii, os objetivos desta pesquisa foram analisar a repartição da precipitação, o balanço de radiação acima do dossel, o perfil da temperatura do ar e comparar algumas características hidrometeorológicas desta floresta com as características em uma área aberta (gramado) e em uma área campestre de cerrado (pastagem). Na floresta foram instaladas estações meteorológicas automáticas no alto de uma torre e no interior. A repartição da precipitação resultou, pela medição manual, em uma precipitação interna de 75,2%, um escoamento pelo tronco de 0,5% e uma interceptação de 24,3% na floresta. Pela medição automática obteve-se uma precipitação interna de 78,7%. O albedo da floresta apresentou um valor médio de 12,8% e a radiação líquida variou de 6,0 MJm-2dia-1 a 14,2 MJm-2dia-1\'. A diferença da temperatura média do ar, no dossel e no interior da floresta, foi de 0,4ºC. Esta pesquisa apresenta uma grande contribuição para o cenário nacional na área de monitoramento hidrometeorológico de florestas. / The government of São Paulo State, Brazil, forty years ago, carried out a program of introduction of forest species with the main objective to consolidate the Pinus culture in the State. Some of these forests were implanted in areas of the Cerrado that were degraded due their use for grassland. The aim of the present work was to verify the hydrometeorologycal characteristics of Pinus elliottii forest, located in Cerrado, in the central region of São Paulo State, and to compare some characteristics among forest, grassland and lawn. In the forest were installed two automatic meteorological stations, one on the tower top and other inside of the forest. The partitionings of the precipitation by manual measurement were 75.2% for throughfall, 0.5% for stemflow and 24.3% for forest interception. By automatic measurement it was obtained 78.7% for throughfall. Forest\'s albedo presented an average value of 12.8% and net radiation ranged from 6.0 MJm-2day-1 to 14.2 MJm-2day-1. The diference of average air temperature between the canopy and the interior of the forest was 0.4ºC. This study presents a great contribuition to the national ambit of the hydrometeorologycal monitoring in forests.
97

Efeito da banana da Terra verde e do albedo do maracujá sobre o perfil lipídico de ratos

BARBOSA, Eloiza Helena Carrijo 07 April 2011 (has links)
Made available in DSpace on 2014-07-29T15:23:43Z (GMT). No. of bitstreams: 1 Dissertacao Eloiza Helena Carrijo Barbosa.pdf: 344169 bytes, checksum: 2878663ff33adc099106b1b5b4a2e97e (MD5) Previous issue date: 2011-04-07 / Were prepared meal green plantain and albedo of passion for the development of this work. After determining the chemical composition of the meal there was a biological test aimed to evaluate the effects of soluble fiber present in the flour of passion fruit albedo and resistant starch of the flour of green plantain, and the mixture of the meal on the levels lipid levels of hypercholesterolemic rats. For testing we used 40 male Wistar rats were divided into five groups of eight rats each. Four supplemented diets were prepared with high concentration of soluble fiber and resistant starch from the flour of passion fruit peel and green plantain respectively and a standard diet. The experimental groups were divided into Banana - 10% of resistant starch and 5% cellulose, Passion Fruit - 10% soluble fiber and 5% cellulose, Mix - 5% resistant starch, 5% cellulose and 5% soluble fiber , Cellulose - 15% cellulose and Standard. The Banana group had a lower intake of diet if differing from other groups. The fecal weight was higher in groups Passion Fruit, pulp and mix. The results show the potential beneficial effect of soluble fiber intake in the control of hypercholesterolemia and soluble and insoluble fiber on intestinal transit. Resistant starch from the green plantain results were not significant on the serum lipid profile of rats. It follows therefore that the albedo of the flour mixture of flour and passion of passion with the albedo of green plantain modulated so as to reduce the serum lipid profile in rats fed a hypercholesterolemic diet, this was probably due to the presence Soluble fiber in both diets since the isolation of the diet that contained only resistant starch from the flour of green plantain not influence significantly the lipid profile of rats. / Foram elaboradas farinhas de banana da terra verde (Musa AAB- Terra) e albedo de maracujá (Passiflora edulis f. flavicarpa) para o desenvolvimento do presente trabalho. Após determinação da composição química dessas farinhas realizou-se um ensaio biológico cujo objetivo foi avaliar os efeitos da farinha do albedo de maracujá (rica em fibra solúvel), da farinha de banana da terra verde (rica em amido resistente) sobre os níveis lipídicos de ratos com dieta hipercolesterolêmica. Para o ensaio foram utilizados 32 ratos Wistar machos divididos em quatro grupos de oito ratos cada. Foram elaboradas três dietas hiperlipídicas,com concentrações variadas de fibra solúvel (proveniente da farinha do albedo de maracujá), de amido resistente (proveniente da farinha de banana da terra verde) de fibra insolúvel (celulose) e uma dieta padrão. Os grupos experimentais foram divididos em Grupo Banana dieta contendo 25,00% de farinha de banana da terra verde, correspondendo a 10% de amido resistente; Grupo Maracujá dieta contendo 34,77% de farinha de albedo de maracujá, correspondendo a 10% de fibra solúvel; Grupo Celulose dieta contendo 15% de celulose, correspondendo a 15% de fibra insolúvel e Grupo Padrão dieta padrão. O amido resistente proveniente da farinha da banana da terra verde no Grupo Banana não apresentou resultado significativo sobre o perfil lipídico sérico dos ratos. Já o grupo maracujá apresentou resultados positivos na redução do perfil sérico. Portanto a fibra solúvel presente na farinha do albedo de maracujá demonstrou ter potencial efeito benéfico na redução do perfil lipídico dos ratos alimentados com uma dieta hiperlipídica. Nas análises do peso das fezes dos ratos, observou-se um aumento de volume fecal nos grupos Maracujá e Celulose, indicando que a ingestão tanto de fibras solúveis como insolúveis tem capacidade de melhora do trânsito intestinal.
98

Condições de contorno albedo para cálculos globais de reatores nucleares térmicos com o modelo de ordenadas discretas a dois grupos de energia / Albedo boundary conditions for thermal nuclear reactors global calculations with two energy group discrete ordinates formulations

Carlos Eduardo de Araújo Nunes 28 November 2011 (has links)
Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Como eventos de fissão induzida por nêutrons não ocorrem nas regiões nãomultiplicativas de reatores nucleares, e.g., moderador, refletor, e meios estruturais, essas regiões não geram potência e a eficiência computacional dos cálculos globais de reatores nucleares pode portanto ser aumentada eliminando os cálculos numéricos explícitos no interior das regiões não-multiplicativas em torno do núcleo ativo. É discutida nesta dissertação a eficiência computacional de condições de contorno aproximadas tipo albedo na formulação de ordenadas discretas (SN) para problemas de autovalor a dois grupos de energia em geometria bidimensional cartesiana. Albedo, palavra de origem latina para alvura, foi originalmente definido como a fração da luz incidente que é refletida difusamente por uma superfície. Esta palavra latina permaneceu como o termo científico usual em astronomia e nesta dissertação este conceito é estendido para reflexão de nêutrons. Este albedo SN nãoconvencional substitui aproximadamente a região refletora em torno do núcleo ativo do reator, pois os termos de fuga transversal são desprezados no interior do refletor. Se o problema, em particular, não possui termos de fuga transversal, i.e., trata-se de um problema unidimensional, então as condições de contorno albedo, como propostas nesta dissertação, são exatas. Por eficiência computacional entende-se analisar a precisão dos resultados numéricos em comparação com o tempo de execução computacional de cada simulação de um dado problema-modelo. Resultados numéricos para dois problemas-modelo com de simetria são considerados para ilustrar esta análise de eficiência. / As neutron fission events do not take place in the non-multiplying regions of nuclear reactors, e.g., moderator, reflector, and structural core, these regions do not generate power and the computational efficiency of nuclear reactor global calculations can hence be improved by eliminating the explicit numerical calculations within the non-multiplying regions around the active domain. Discussed here is the computational efficiency of approximate discrete ordinates (SN) albedo boundary conditions for two-energy group eigenvalue problems in X,Y geometry. Albedo, the Latin word for whiteness, was originally defined as the fraction of incident light reflected diffusely by a surface. This Latin word has remained the usual scientific term in astronomy and in this dissertation this concept is extended for the reflection of neutrons. The non-standard SN albedo substitutes approximately the reflector region around the active domain, as we neglect the transverse leakage terms within the nonmultiplying reflector. Should the problem have no transverse leakage terms, i.e., onedimensional slab geometry, then the offered albedo boundary conditions are exact. By computational efficiency we mean analyzing the accuracy of the numerical results versus the CPU execution time of each run for a given model problem. Numerical results to two symmetric test problems are shown to illustrate this efficiency analysis.
99

Condições de contorno albedo para cálculos globais de reatores nucleares térmicos com o modelo de ordenadas discretas a dois grupos de energia / Albedo boundary conditions for thermal nuclear reactors global calculations with two energy group discrete ordinates formulations

Carlos Eduardo de Araújo Nunes 28 November 2011 (has links)
Fundação Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro / Como eventos de fissão induzida por nêutrons não ocorrem nas regiões nãomultiplicativas de reatores nucleares, e.g., moderador, refletor, e meios estruturais, essas regiões não geram potência e a eficiência computacional dos cálculos globais de reatores nucleares pode portanto ser aumentada eliminando os cálculos numéricos explícitos no interior das regiões não-multiplicativas em torno do núcleo ativo. É discutida nesta dissertação a eficiência computacional de condições de contorno aproximadas tipo albedo na formulação de ordenadas discretas (SN) para problemas de autovalor a dois grupos de energia em geometria bidimensional cartesiana. Albedo, palavra de origem latina para alvura, foi originalmente definido como a fração da luz incidente que é refletida difusamente por uma superfície. Esta palavra latina permaneceu como o termo científico usual em astronomia e nesta dissertação este conceito é estendido para reflexão de nêutrons. Este albedo SN nãoconvencional substitui aproximadamente a região refletora em torno do núcleo ativo do reator, pois os termos de fuga transversal são desprezados no interior do refletor. Se o problema, em particular, não possui termos de fuga transversal, i.e., trata-se de um problema unidimensional, então as condições de contorno albedo, como propostas nesta dissertação, são exatas. Por eficiência computacional entende-se analisar a precisão dos resultados numéricos em comparação com o tempo de execução computacional de cada simulação de um dado problema-modelo. Resultados numéricos para dois problemas-modelo com de simetria são considerados para ilustrar esta análise de eficiência. / As neutron fission events do not take place in the non-multiplying regions of nuclear reactors, e.g., moderator, reflector, and structural core, these regions do not generate power and the computational efficiency of nuclear reactor global calculations can hence be improved by eliminating the explicit numerical calculations within the non-multiplying regions around the active domain. Discussed here is the computational efficiency of approximate discrete ordinates (SN) albedo boundary conditions for two-energy group eigenvalue problems in X,Y geometry. Albedo, the Latin word for whiteness, was originally defined as the fraction of incident light reflected diffusely by a surface. This Latin word has remained the usual scientific term in astronomy and in this dissertation this concept is extended for the reflection of neutrons. The non-standard SN albedo substitutes approximately the reflector region around the active domain, as we neglect the transverse leakage terms within the nonmultiplying reflector. Should the problem have no transverse leakage terms, i.e., onedimensional slab geometry, then the offered albedo boundary conditions are exact. By computational efficiency we mean analyzing the accuracy of the numerical results versus the CPU execution time of each run for a given model problem. Numerical results to two symmetric test problems are shown to illustrate this efficiency analysis.
100

Características hidrometeorológicas em uma floresta de Pinus elliotii no Cerrado / Hydrometeorologycal characteristics of the Pinus elliotii forest in Cerrado

Sílvio Dias Pereira Neto 28 March 2003 (has links)
O governo do Estado de São Paulo, na década de 60, realizou um programa de introdução de florestas do gênero Pinus para consolidar esta cultura no estado. Algumas destas florestas foram implantadas em áreas do Cerrado, que estavam degradadas devido à utilização para pastagens. Com a intenção de contribuir para um melhor entendimento das características hidrometeorológicas em uma floresta de P. elliotii, os objetivos desta pesquisa foram analisar a repartição da precipitação, o balanço de radiação acima do dossel, o perfil da temperatura do ar e comparar algumas características hidrometeorológicas desta floresta com as características em uma área aberta (gramado) e em uma área campestre de cerrado (pastagem). Na floresta foram instaladas estações meteorológicas automáticas no alto de uma torre e no interior. A repartição da precipitação resultou, pela medição manual, em uma precipitação interna de 75,2%, um escoamento pelo tronco de 0,5% e uma interceptação de 24,3% na floresta. Pela medição automática obteve-se uma precipitação interna de 78,7%. O albedo da floresta apresentou um valor médio de 12,8% e a radiação líquida variou de 6,0 MJm-2dia-1 a 14,2 MJm-2dia-1\'. A diferença da temperatura média do ar, no dossel e no interior da floresta, foi de 0,4ºC. Esta pesquisa apresenta uma grande contribuição para o cenário nacional na área de monitoramento hidrometeorológico de florestas. / The government of São Paulo State, Brazil, forty years ago, carried out a program of introduction of forest species with the main objective to consolidate the Pinus culture in the State. Some of these forests were implanted in areas of the Cerrado that were degraded due their use for grassland. The aim of the present work was to verify the hydrometeorologycal characteristics of Pinus elliottii forest, located in Cerrado, in the central region of São Paulo State, and to compare some characteristics among forest, grassland and lawn. In the forest were installed two automatic meteorological stations, one on the tower top and other inside of the forest. The partitionings of the precipitation by manual measurement were 75.2% for throughfall, 0.5% for stemflow and 24.3% for forest interception. By automatic measurement it was obtained 78.7% for throughfall. Forest\'s albedo presented an average value of 12.8% and net radiation ranged from 6.0 MJm-2day-1 to 14.2 MJm-2day-1. The diference of average air temperature between the canopy and the interior of the forest was 0.4ºC. This study presents a great contribuition to the national ambit of the hydrometeorologycal monitoring in forests.

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