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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.
411

ReduÃÃo da evaporaÃÃo em tanques de 20M2 por filmes monomoleculares de hexadecanol e suas influÃncias na qualidade da Ãgua / EVAPORATION REDUCTION IN 20m2 PANS USING MONOMOLECULAR FILMS OF HEXADECANOL AND ITS INFLUENCES IN WATER QUALITY

Luewton Lemos Felicio Agostinho 09 February 2007 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A regiÃo Nordeste do Brasil, com suas condiÃÃes de semi-Ãrido, tem sofrido devido aos altos Ãndices de evaporaÃÃo que apresenta. Tais Ãndices propiciam grandes perdas para a regiÃo, de uma forma geral, e mesmo para o paÃs. O presente trabalho estuda uma das ferramentas mais populares do mundo para controle da evaporaÃÃo em reservatÃrios superficiais - filmes monomoleculares de hexadecanol - e as conseqÃÃncias da sua aplicaÃÃo na qualidade da Ãgua. Foram utilizados reservatÃrios de 20m2 de Ãrea (Tanques Russos) construÃdos na EstaÃÃo AgrometeorolÃgica da Universidade Federal do CearÃ, Campus do Pici. Os experimentos compreenderam 03 anos de observaÃÃo onde foram avaliados a eficiÃncia do filme, uma correlaÃÃo estatÃstica entre a reduÃÃo da evaporaÃÃo e alguns fatores climatolÃgicos (velocidade do vento, umidade relativa do ar, radiaÃÃo lÃquida, radiaÃÃo global e temperatura do ar), a influencia da aplicaÃÃo do filme nas caracterÃsticas biÃticas (fungos, fitoplÃnctons, baterias e peixes) e abiÃticas (turbidez, temperatura da Ãgua, condutividade elÃtrica, pH e salinidade) da Ãgua. Foram ainda avaliadas a velocidade de dispersÃo do surfactante na superfÃcie lÃquida e alguns efeitos adversos como à formaÃÃo de estrias. Os resultados apontaram que o produto à capaz de reduzir a evaporaÃÃo em cerca de 40% nas condiÃÃes do estudo. Foi ainda visualizado no estudo estatÃstico que a velocidade do vento e a temperatura do ar apresentaram influencias estatisticamente significativas na reduÃÃo da evaporaÃÃo. No que diz respeito aos parÃmetros abiÃticos a aplicaÃÃo do filme sà trouxe alteraÃÃo significativa na temperatura da Ãgua. As espÃcies fitoplanctÃnicas avaliadas e os peixes nÃo sofreram influencia do surfactante tambÃm, entretanto, foi observada certa seletividade nos fungos e bactÃrias. / Brazilian Northeast region, with its Semi-Arid conditions, has suffered difficulties due to its high evaporation levels. This evaporation brings great losses to the region and, in consequence, to the country. The present work studies one of the world most popular tools to control evaporation in open pans â hexadecanol monomolecular films - and the consequences of its application in water quality. It was used open pans of 20m2 of area (Russian Pans) built on Agrometeorological Station of Cearà University in Fortaleza. The experiments takes 3 years where were evaluated the film effectiveness, the statistical correlation between the evaporation reduction and the weather conditions, and the influence of the film application on biotic (phytoplankton, bacteria, fungus and fishes) and abiotic (turbidity, temperature, electrical conductivity, pH and salinity) characteristics of the water. It was also evaluated the dispersion velocity of the surfactant and the formation of âstringsâ. Results show that the product is able to reduce evaporation in 40% in Semi-Arid conditions. It was also presented that wind velocity and air temperature have some influence on evaporation reduction. Concerning the abiotic parameters the film application just causes significant alteration in water temperature. Phytoplankton and fishes does not suffer influences of the surfactante also, but it was notice some selectivity in fungus and bacteria species.
412

Iodeto de mercúrio produzido por evaporação de solvente: cristais obtidos usando etanol e tetrahidrofurano, e filmes híbridos obtidos usando polímeros isolantes / Mercuric iodide produce by solvent evaporation: crystals obtained by ethanol and tetrahydrofuran, and hybrids films obtained by isulator polymers

Julio César Ugucioni 05 August 2009 (has links)
O iodeto de mercúrio vermelho (?-HgI2 ou comumente conhecido na literatura como HgI2) vem sendo largamente estudado para utilização em detectores de radiação -X e -? por apresentar alta faixa de energia proibida (gap de energia = 2,13eV), alto número atômico (ZHg = 80; ZI = 53) e alta densidade (6,4 mg/ml), além de outras propriedades que auxiliam na absorção destes tipos de radiação. A obtenção de filmes e cristais usando uma técnica de baixo custo é abordada neste trabalho. A técnica que obtenção de cristais utilizada foi a evaporação de solvente, que consiste na evaporação de um solvente volátil de uma solução preparada com sal de HgI2. Os solventes voláteis utilizados foram etanol, tetrahidrofurano (THF) e algumas misturas de ambos. Duas principais condições de evaporação foram testadas: na presença de luz ambiente (claro) e na ausência desta (escuro) em temperatura ambiente. Somente para o etanol obteve-se cristais com controle de temperatura (temperatura de 40°C) dentro de estufa no escuro. Observou-se, como resultado geral, que os cristais apresentam um aumento da desorganização estrutural quando se adiciona THF. Como esperado, isso se refletiu nas propriedades elétricas, diminuindo a resistividade (?) e energia de ativação (Ea) destes materiais. Além disso, é observado para os cristais obtidos com etanol (claro, escuro e estufa a 40°) diferentes resultados estruturais, ópticos, elétricos e de fotocondutividade. Em relação aos resultados estruturais, as condições influenciaram três orientações distintas que se acredita ser devido a variações energéticas relacionadas a temperatura e excitação eletrônica promovida pela luz. Anisotropia também foi observada pela análise dos resultados do espalhamento Raman. Medidas ópticas destacaram a presença principal de contribuições referentes a transições de elétrons da banda de valência a banda de condução (transição excitônica). Os cristais obtidos no claro e estufa apresentam ainda contribuições de transições de elétrons relacionadas a desorganização estrutural e ligações pendentes. Quanto as medidas elétricas, observou-se que o cristal obtido no escuro com etanol (E100E) apresentou os maiores valores de ? e Ea (2,67x108 ? .cm e 1,13 eV) e resultados de fotocondutividade mostraram baixos valores da relação fotocorrente corrente de escuro. Os filmes híbridos de iodeto de mercúrio foram obtidos usando a mesma técnica com presença de polímeros isolantes que atuaram como matriz de sustentação dos cristais de HgI2. Os polímeros utilizados foram poliamida (PA), policarbonato (PC) e poliestireno (PS). Estes eram dissolvidos em THF e o sal de HgI2 era acrescido a esta solução. Filmes foram confeccionados variando a temperatura de evaporação do THF para todos os polímeros, e para PS (que apresenta maior resistência a radiação na faixa de radiodiagnóstico) foi realizado estudos de variação da concentração de polímero (de 20 a 200mg/ml) e da massa de iodeto de mercúrio (de 0,6 a 2,0g). Com o acréscimo dos polímeros isolantes nos filmes, nota-se que se tem um aumento de ?, ainda maior que o observado para os cristais. Também a relação entre fotocondutividade e corrente de escuro é aumentada. No entanto, não se observa uma formação homogênea no filme quando analisamos morfologicamente, sendo possível ver cristais dispersos. Por fim, estes filmes apresentaram um gap de energia de 2,1 eV, muito próximo do obtido para cristais HgI2 (2,13 eV) / Red mercuric iodide (?-HgI2 or known in literature as HgI2) has been widely studied for X- and ?- radiation detector applications because of the high gap energy (2.13 eV), high atomic number (ZHg = 80, ZI = 53), high density (6.4 mg/ml) and other properties that raise the absorption of these types of radiation. Films and crystals were obtained using a low-cost technique that is discussed in this work. The technique used was solvent evaporation, which is the evaporation of volatile solvent from solution prepared with HgI2 salt. The solvents were ethanol, tetrahydrofuran (THF) and some mixtures of both. Two main evaporation conditions were experimented: in (Light) or without (Dark) ambient light presence at room temperature. Only ethanol was obtained crystals with temperature control (constant temperature of 40o in dark oven. It was observed, as general result, that the crystals show an increase of structural disorder when it was added THF for initial solution. This reflects in electrical properties, decreasing resistivity (?) and activation energy (Ea) from this material. Furthermore, it is observed for ethanol crystals (Light, Dark, and Oven at 40o) different structural, optical, electrical and photoconductivity results. In relation to structure, the conditions influenced three distinct orientations that it is energetic variations related to temperature and light excitation. Anisotropy was also observed by Raman scattering analysis. Optical measurements present main contributions of electron transitions from valence to conduction band (excitonic transitions). The Light and Oven crystals show contributions related to structural disorder and dangling bounds. Electrical studies highlighted higher values of ? and Ea (2.67x10-8 ?.cm e 1.13 eV), and photoconductive curves has lower photocurrent-dark current relation. HgI2 hybrid films were obtained using the same technique (solvent evaporation) with insulator polymers forming a matrix to sustain the crystals. The polymers were polyamide (PA), polycarbonate (PC) and polystyrene (PS). These were dissolved in THF and HgI2 salt was added to this solution. Films were made varying the evaporation temperature, and for PS (whose shows the best resistance for diagnostic radiation) was varying polymer concentration (from 20 to 200mg/ml) and HgI2 mass (from 0.6 to 2.0). It was observed an increase of ? adding the polymers in relation of crystals. The photocurrent-dark current relation is also higher than crystals. However, it was not seen homogeneous surface, where it was seen dispersed crystals by SEM images. Finally, the films show energy gap of 2.1 eV, very close to single crystal of literature.
413

Quantificação da alteração no balanço hídrico devido à cavas de mineração utilizando lisímetros e tanques de evaporação / Quantifying the alteration in water balance due to the mining caves using lysimeters and evaporation tanks

Manoel Camilo Moleiro Cabrera 16 September 2011 (has links)
A quantificação da alteração no balanço hídrico, provocado pelo surgimento de espelhos dágua devido a atividades mineradoras, é fundamental para se avaliar o impacto das atividades antrópicas no ciclo hidrológico. O presente trabalho aborda a análise da perda de água em superfície vegetada sobre diferentes solos comparando com a perda de água em superfície liquida livre. Para isso foi usado um experimento composto por um lisímetro contendo solo argiloso, outro arenoso, um tanque de evaporação enterrado no solo e o conceito de balanço hídrico. E assim realizou-se um estudo sobre as alterações nos fluxos de água entre o solo, planta e atmosfera, quando ocorre à transformação de uma área coberta por vegetação rasteira, para uma superfície líquida exposta diretamente as mesmas condições climáticas. Com a expansão das cavas de mineração do tipo fechada, muitas paisagens naturais que antes eram cobertas por vegetação rasteira foram se transformando em cavas inundadas à céu aberto e depois com a desativação das atividades mineradoras na área, essas cavas inundadas se tornam lagoas, muitas vezes sem função alguma, o resultado deste trabalho demonstra que essa transformação altera o balanço hídrico. Os dois lisímetros empregados foram do tipo Drenagem com um nível fixo de água em seu interior, simulando o armazenamento subterrâneo de água. As superfícies dos lisímetros estavam cobertas por grama do tipo Batatais (Paspalum notatum Flugge) com altura de 0,08 a 0,12 m. O tanque de evaporação também foi mantido com o nível constante e alimentação continua de água. Ambos os lisímetros e o tanque de evaporação estavam equipados com um sistema de caixas com torneira de boia e caixas de drenagem, com finalidade de escoar rapidamente a precipitação. Os volumes de água que percolaram através do lisímetro com solo argiloso (lis-arg), foram similares aos do lisímetro com solo arenoso (lis-aren), indicando a boa drenagem efetuada pelo solo argiloso. O lisímetro com argila não necessitou de reposições diárias de água em seu interior para a manutenção do nível durante o período chuvoso da região, porém o desenvolvimento da grama na superfície evaporante do lisímetro não foi satisfatório. As medidas lisimétricas, permitiram uma melhor compreensão sobre os efeitos da mineração e transformação de paisagem no balanço hídrico em solos argilosos e arenosos. Os resultados obtidos indicaram que a perda de água em solo argiloso coberto por grama batatais aumentou 237 mm quando 1 \'M POT.2\' deste tipo de superfície foi substituída por espelho dágua. O solo arenoso vegetado quando substituído por superfície teve um aumento de 200 mm da perda de água para a atmosfera. / The quantification of changes in water balance, caused by the appearance of water features due to mining activities, it is essential to assess the impact of human activities on the hydrological cycle. This paper deals with the analysis of water loss over different vegetated surface soils compared to the loss of water in liquid free surface. Was used for this experiment consists of a lysimeter containing a clay soil, one sandy, an evaporation tank buried in the soil and the concept of water balance. And so do a study on changes in water fluxes between soil, plant and atmosphere, the transformation occurs when an area covered by low vegetation, to a liquid surface directly exposed to the same climatic conditions. With the expansion of mining pits of the \"closed\", many natural landscapes that were once covered by low vegetation were becoming flooded caves in the open air and then with the deactivation of mining activities in the area, these arches become flooded ponds, often without any function, the result of this work shows that this transformation changes the water balance. The two lysimeters were employees of the \"Drainage\" with a fixed level of water inside, simulating the underground storage of water. The surfaces of the lysimeters were covered with grass type Bahiagrass (Paspalum notatum Flügge) in height from 0.08 to 0.12 m. The evaporation tank was maintained constant level with the water and food remains. Both lysimeter and evaporation pan were equipped with a speaker system with tap float boxes and drainage, with the purpose of draining the precipitation quickly. The volumes of water percolating through the lysimeter with clay soil (lis-arg), were similar to the lysimeter with sandy soil (lis-aren), indicating good drainage performed by clay soil. The clay lysimeter did not require daily replacement of water inside to maintain the level during the rainy season in the region, but the development of grass on the evaporating surface of the lysimeter was not satisfactory. Measures lysimetric allowed a better understanding of the effects of mining and processing of the landscape water balance in sandy and clay soils. The results indicated that the loss of water in clay soil covered with bahiagrass increased when a 237 mm \'M POT.2\' of this type has been replaced by surface water body. The vegetated sandy soil when the surface was replaced by an increase of 200 mm of water loss to the atmosphere.
414

Contribuição ao estudo do mecanismo de formação e precipitação de sais de sódio em evaporadores de licor negro de eucalipto visando seu controle e prevenção / Contribution to the study of sodium salts formation and precipitation mechanism in eucalyptus black liquor evaporators aiming their control and prevention

Leite, Brenno Santos 21 August 2018 (has links)
Orientador: José Vicente Hallak d'Angelo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T16:01:06Z (GMT). No. of bitstreams: 1 Leite_BrennoSantos_D.pdf: 2261733 bytes, checksum: 645cd7fdea0a4b3aadd5357222e37a40 (MD5) Previous issue date: 2012 / Resumo: O licor negro é um subproduto do processo de digestão da madeira em fábricas de celulose e papel, composto por frações orgânicas e inorgânicas. Após o processo de digestão, o licor negro apresenta um teor de sólidos secos de aproximadamente 15% e para que possa ser queimado na caldeira de recuperação química é necessário elevar esse teor para valores próximos de 75%. Este processo de concentração do licor é feito em um sistema de evaporação múltiplo efeito. Propriedades físico-químicas do licor, tais como massa específica, teor de sólidos secos, viscosidade e teor de sais de sódio sofrem forte dependência do tipo de madeira processada e das condições de operação durante o processo de digestão. O conhecimento destas propriedades e da relação entre elas auxilia no controle do processamento do licor e pode permitir um maior aproveitamento energético de toda a unidade de recuperação. Quando o licor negro atinge altas concentrações de sólidos (superiores a 50%), observa-se precipitação de sais responsáveis pela formação de incrustações na superfície de transferência de calor dos evaporadores e concentradores, reduzindo a eficiência do sistema de evaporação. O presente trabalho tem como objetivo geral, investigar e compreender o mecanismo de formação e precipitação de sais de sódio, durante o processo de concentração do licor negro, os quais podem formar incrustações que prejudicam o bom desempenho do processo, por meio de um estudo e correlação de suas propriedades físico-químicas, avaliando sua influência na solubilidade dos sais inorgânicos presente no licor. Ressalta-se que os primeiros sais a precipitarem são os sais de sódio, mais especificamente o carbonato e o sulfato de sódio. Sendo assim, compreender o mecanismo que promove a redução de sua solubilidade é muito importante para entender o comportamento dos demais sais presentes no licor negro. Foi possível desenvolver um modelo capaz de avaliar a solubilidade do sulfato de sulfato de sódio considerando as características especificas do licor negro. Também, com base neste modelo de solubilidade foi possível compreender a lógica do efeito da inversão de solubilidade de um determinado sal sobre o comportamento do sistema, possibilitando compreender o mecanismo de formação das primeiras precipitações no licor negro de eucalipto / Abstract: In pulp and paper mills the aqueous solution extracted from the pulping process in the wood digester is named black liquor, which consists of organic and inorganic compounds. When leaving the digester sector black liquor has about 15 %/mass of solids and to be used as a fuel in the recovery boiler it is necessary to raise this solids content to 75 %/mass, removing water in a battery of multiple effect evaporators. Some black liquor physical properties, such as density, solids content, viscosity and sodium salts content, are strongly dependent on the kind of wood processed (hardwood or softwood) and on operating conditions during the digestion process. Knowledge and comprehension of the relationship between these physical properties of black liquor are essential for studies aiming at a better energetic performance of the black liquor evaporation unit. When black liquor reaches higher solids content (above 50 %/mass), scaling formation is observed on the heat transfer surfaces of evaporators and concentrators, due to precipitation of sodium salts, reducing the overall efficiency of this equipment. The aim of this work is to investigate and comprehend the mechanism of formation and precipitation of sodium salts in eucalyptus black liquor evaporators, through the study of the relationship between some physical proprieties (density, viscosity, total solids content) evaluating their influence over the solubility of sodium salts content in industrial black liquor samples. This greater comprehension and knowledge of the mechanism which is responsible for the reduction of the solubility of these salts is very important for the development of alternative methods to avoid or reduce scaling formation. The results have shown that it is possible to use a model to estimate sodium sulfate solubility limit and comprehend the formation mechanism of the first scaling and the behavior of the salts in the system / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutor em Engenharia Química
415

L'évaporation dans le bilan hydrologique des étangs du Centre-Ouest de la France (Brenne et Limousin) / Evaporation in water balance of ponds in the French Midwest (Brenne and Limousin)

Aldomany, Mohammad 12 September 2017 (has links)
L’effacement des plans d’eau (petits ou grands) du continuum hydrographique est le nouveau dogme français lié à l’interprétation de la Directive Cadre européenne sur l'Eau (DCE-2000) dans la Loi sur l’Eau et les Milieux Aquatiques (LEMA-2006). En effet, cette stratégie se base sur des idées ne reposant sur aucune mesure exacte de l’influence des plans d’eau, supposée néfaste, sur la quantité d’eau s’écoulant dans les réseaux hydrographiques aval. Face à ce paradoxe notable entre réglementation appliquée et absence de mesures directes de l'évaporation des étangs de France métropolitaine, il apparaît un double besoin, tant en géographie fondamentale qu’en recherche appliquée, pour une étude détaillée sur l'évaporation et le bilan hydrologique des étangs.Sur le plan méthodologique, cette étude montre que le bac flottant en plastique transparent est l’outil le plus à même de mesurer l'évaporation des étangs. Sur le plan conceptuel, le travail intensif de terrain a conduit à établir une nouvelle formule empirique ''Aldomany'' qui peut fournir des estimations fiables de l'évaporation des plans d'eau peu profonds à l'échelle annuelle, mensuelle et journalière en utilisant seulement des données météorologiques facilement accessibles. Dans une optique de gestion, cette étude montre que la perte en eau provoquée par un étang s’apparente à celle d’une chênaie de même superficie et que les propos à charge tenus contre les étangs méritent d’être nuancés, les étangs de la Brenne étant bien en partie responsables de l'étiage estival de la Claise, alors que les étangs limousins jouent un rôle plutôt positif en assurant un bon débit estival du réseau hydrographique de cette région. / The erasure of water bodies (large or small) of the hydrographic continuum is the new French dogma related to the interpretation of the European Water Framework Directive (WFD-2000) in the Water and Environment Act (LEMA-2006). In fact, this strategy is based on ideas that are not based on any exact measure of the influence of the supposedly harmful water bodies on the amount of water flowing into the downstream hydrographic networks. In view of this remarkable paradox between applied regulation and the absence of direct measurements of the evaporation of metropolitan France's ponds, there appears to be a dual need in both basic geography and applied research for a detailed study on evaporation and the water balance of ponds.Methodologically, this study shows that the evaporation floating pan constructed of transparent plastic is the most suitable tool for measuring the evaporation of ponds. Conceptually, intensive field work has led to the development of a new empirical formula ''Aldomany'' that can provide reliable estimates of the evaporation of shallow water bodies at on an annual, monthly and daily basis using only readily available meteorological data. From a management perspective, this study shows that the loss of water caused by apond is similar to that of an oak has the same area and that the statements against the ponds should bere considered, the ponds of La Brenne being partly responsible for the summer low water of the Claise,while the Limousin's ponds play a rather positive role in ensuring a good summer flow of the hydrographic network of this region.
416

Modélisation mixte et télédétection multi-résolution de l'évaporation du sol / Mixed modeling and multi-rsolution remote sensing of soil evaporation

Stefan, Vivien 06 December 2016 (has links)
L'évapotranspiration (ET) et ses deux composantes, l'évaporation du sol et la transpiration des plantes, jouent un rôle crucial dans le cycle hydrologique, en particulier dans les régions semi-arides. Le suivi de l'évaporation du sol à des échelles multiples est particulièrement intéressant pour une multitude d'applications agronomiques, hydrologiques, météorologiques et climatiques, pour lesquelles la télédétection a un grand potentiel via deux observables clés liées à l'évaporation: la température de surface (Land Surface Temperature - LST) et l'humidité du sol en surface (Soil Moisture - SM). Cette thèse avait pour but d'améliorer la représentation spatio-temporelle de l'évaporation du sol, par une modélisation multi-échelle capable d'utiliser la synergie des données de télédétection disponibles. Une nouvelle méthodologie a été développée afin d'estimer l'efficacité évaporative du sol ou SEE (Soil Evaporative Efficiency, définie comme le rapport entre l'évaporation du sol réelle et celle potentielle), avec une résolution comprise entre 100 m et 40 km. Elle combine l'humidité du sol dérivée à 40 km de résolution des données micro-ondes, la température de surface, le couvert végétal et l'albédo de surface issues des capteurs optiques avec une résolution spatiale variant de 100 m and 1 km, et des données météorologiques. Cette approche a été testée sur des zones irriguées semi-arides au Maroc, au Mexique et en Espagne. Dans une première étape, un modèle du bilan d'énergie du sol (EBsoil) a été proposé pour estimer les limites humide/sèche d'un modèle de l'ET basé sur la LST. Les sorties du modèle EBsoil ont été validées avec des mesures in situ de la température du sol réalisées au Maroc. Les estimations de l'ET obtenues soit uniquement à partir des données de télédétection, soit en utilisant EBsoil, ont ensuite été comparées avec une ET de référence sur le site mexicain pour des résolutions de 100 m et 1 km. Les résultats ont montré que l'intégration de EBsoil améliore les estimations de l'ET à la résolution de 1 km. L'étape suivante s'est concentrée sur la dynamique temporelle de la SEE, en utilisant la technique de la modélisation globale. Cette approche a été utilisée jusqu'à présent pour un petit nombre de contextes environnementaux, avec encore moins de modèles obtenus qui sont en mesure de reproduire la dynamique d'origine. Pour la première fois, un modèle chaotique de dimension quatre a été obtenu pour le cycle journalier de la SEE, capable de reproduire la dynamique de la variable avec une bonne approximation dans l'espace des phases. Dans une dernière étape, les deux approches de télédétection utilisées pour calculer la SEE - en fonction de la LST ou de la SM - ont été combinées dans un algorithme de désagrégation (DISPATCH) des données SM SMOS (Soil Moisture and Ocean Salinity). EBsoil a été intégré dans DISPATCH et un nouvel algorithme a été développé: DISPATCH-E. Une évaluation indirecte de l'approche de modélisation de la SEE a été implémentée sur le site espagnol en comparant la SM DISPATCH-E aux mesures in situ. L'intégration de EBsoil améliore significativement la SM désagrégée à 1 km de résolution. De plus, elle fournit des points de référence pour l'étalonnage des modèles multi-résolution de la SEE, ainsi qu'une évaluation indépendante de l'incertitude des données de télédétection. / Evapotranspiration (ET) and its two main components, soil evaporation and plant transpiration, play a crucial role in the hydrological cycle, especially over semi-arid regions. Monitoring soil evaporation at multiple scales is especially relevant to a multitude of agronomic, hydrologic, meteorological and climatic applications, where remote sensing-based approaches have great potential via two evaporation-related observable variables: the land surface temperature (LST) and the surface soil moisture (SM). The aim of this PhD was to try and improve the spatio-temporal representation of soil evaporation by developing a multi-scale modeling approach that makes use of the synergy between readily available remote sensing data. A new methodology was developed to estimate the soil evaporative efficiency or SEE (ratio of actual to potential soil evaporation) at 100 m to 40 km resolution by combining 40 km resolution microwave-derived SM, 100 m to 1 km resolution thermal-derived LST, 100 m to 1 km resolution reflectance-derived vegetation cover/surface albedo and available meteorological data. The approach was tested over three different semi-arid irrigated areas in Morocco, Mexico and Spain. In a first step, a soil energy balance model (EBsoil) was proposed to improve the determination of the dry/wet boundaries of a LST-based ET model. EBsoil outputs were validated against in situ measurements of dry/wet soil temperatures over the Moroccan site. ET estimates were subsequently derived either from remote sensing data solely or by using EBsoil and intercompared at 100 m and 1 km resolutions with a reference ET over the Mexican site. Results showed that integrating EBsoil improves ET estimates at a medium (1 km) resolution. The next step consisted in looking into the temporal dynamics of SEE, using the global modeling technique, approach used for a very small number of environmental contexts, with even fewer models obtained that are able to reproduce the original dynamics. For the first time ever, a four dimensional chaotic model was obtained for the daily cycle of SEE, able to reproduce the dynamics of the variable with a good approximation in the phase domain. In a final step, the two remote sensing approaches used in deriving SEE - as a function of LST or SM - were combined within a disaggregation algorithm (DISPATCH) of SMOS (Soil Moisture and Ocean Salinity) SM data. EBsoil was integrated in DISPATCH and a new algorithm was developed: DISPATCH-E. An indirect validation of the SEE modeling approach was performed by assessing DISPATCH-E's results in terms of 1 km resolution SM estimates over the Spanish site. Implementing EBsoil significantly improves the downscaled SM. Furthermore it provides reference points for calibrating multi-resolution SEE models, as well as being an independent way of assessing uncertainty in remotely sensed data.
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[en] CRITICAL ANALYSIS OF THE STANDARDS FOR EVALUATING WATER HEATERS USING GAS FUEL / [pt] ANÁLISE CRÍTICA DE NORMAS EXISTENTES PARA AVALIAÇÃO DE AQUECEDORES DE ÁGUA QUE UTILIZAM GÁS COMO COMBUSTÍVEL

MILSON JOSE DE CARVALHO 14 March 2018 (has links)
[pt] No presente trabalho calcula-se a eficiência de um aquecedor de água, sem evaporação, queimando gás combustível com composição química desconhecida. Faz-se a comparação dos resultados obtidos com duas normas que apresentam formas diferentes de cálculo, ASME (1) e NBS (2). Com os resultados finais, sugere-se um procedimento a ser seguido no cálculo de eficiência de aquecedores. / [en] In this research, the thermal efficiency of a sensible water heater is measured and calculated, burning fuel gas with unknown chemical composition. The experimental results are then compared with the calculated values, when using ASME(1) and NBS(2) standard procedures. Finally and procedure is suggested to calculate the thermal efficiency of such heaters.
418

Impact of irrigation development and climate change on the water level of Lake Urmia, Iran

Beygi, Heydar January 2015 (has links)
Lake Urmia, located in the north-west of Iran, is one of the largest hypersaline lakes in the world. In recent years, there has been a significant decrease in the lake’s area and volume by 88% and 80% respectively. An integrated water balance model of the Lake Urmia Drainage Basin (LUDB) and Lake Urmia was developed to identify these main drivers of the significant changes, and to investigate the possible future evolution of the lake under effects of projected climate change and land use change. We used an energy balance method to estimate the evaporation from the lake and the Turc-Langbein method to estimate the evapotranspiration from the drainage basin of the lake. Agricultural irrigation water was introduced to the model as an extra precipitation over the irrigated fields, after being subtracted from the surplus runoff (precipitation−evapotranspiration). The agricultural land development was assumed to be linear that changed from 300000 ha at 1979 to 500000 at 2010, which is consistent with the best available data on the actual irrigation development in the basin. We estimated the annual evaporation over the Lake Urmia and the evapotranspiration over its drainage basin as 932 mm and 287 mm respectively. Our results showed that decreased precipitation and increased temperature over the basin since 1995 could explain 68% of the observed lake level decrease. Irrigation developments during the last four decades were found to be responsible for 32% of the observed lake level decrease. Thus the future lake level of the Lake Urmia is very likely to continue to decrease unless the current climate condition will be followed by a period of increased precipitation. If the current climate conditions will prevail also in the future, even a 20% decrease in the irrigated land area, which is actually quite ambitious, will not make the lake recover to its ecological level at the end of 2020.
419

Etude de la nanostructuration de matériaux énergétiques multi-composants pour application aux poudres propulsives à sensibilités réduites / Study of the nanostructuration of multi-component energetic materials for application to low vulnerability propellants

Le Brize, Axel 13 February 2017 (has links)
Les travaux de thèse présentés dans ce manuscrit ont porté sur l’élaboration et la caractérisation de poudres propulsives à sensibilités réduites. Ceci a été effectué par l’utilisation de matériaux énergétiques relativement insensibles ainsi que par l’emploi du procédé de Spray Evaporation Flash (SFE). Ce dernier a permis d’obtenir des poudres nanostructurées de composition ternaire. La caractérisation de ces poudres propulsives par spectroscopie Raman a permis de mettre en évidence le mécanisme de plastification de la nitrocellulose par les plastifiants employés. Des analyses de microscopie électronique à balayage ont été menées pour étudier la granulométrie de ces échantillons. Leur caractérisation par diffraction des rayons X a permis d’étudier leur structure et leur cristallisation. Des mesures de calorimétrie différentielle à balayage, des essais de tirs en tubes et en bombe manométrique, ainsi que des mesures de sensibilités à divers types de sollicitations, ont permis de montrer que les poudres obtenues sont particulièrement insensibles. / The PhD thesis presented in this manuscript focused on the elaboration and characterization of propellants with reduced sensitivities. This was accomplished by the use of relatively insensitive energetic materials, in conjunction with the application of the Spray Flash Evaporation (SFE) process. The latter made it possible to obtain nanostructured propellants of ternary composition.The characterization of these propellants by Raman spectroscopy revealed the mechanisms ruling the plasticization of nitrocellulose by the plasticizers used. Scanning electron microscopy analyzes were conducted to determine the particle size of these samples. Their characterization by X-ray diffraction allowed to study their structure and their crystallization. These propellants were shown to be particularly insensitive through analyses by differential scanning calorimetry,pyrotechnic tests in tubes and manometric vessels as well as sensitivity measurements to various types of solicitations.
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INFLUÊNCIA DO LASER DE DIODO NA EVAPORAÇÃO DO SOLVENTE DE SISTEMAS ADESIVOS E NA VARIAÇÃO DE TEMPERATURA NA CÂMARA PULPAR / THE INFLUENCE OF DIODE LASER IN SOLVENT EVAPORATION OF ADHESIVE SYSTEMS AND IN TEMPERATURE VARIATION IN THE PULP CHAMBER

Friedrich, Luciana Roggia 24 July 2013 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to evaluate in vitro the influence of diode laser in solvent evaporation of adhesive systems and in the pulp chamber temperature variation. It was carried out in two stages: a) to evaluate the grade of solvent evaporation (GE) by the gravimetric method in which 10 μL of each of the tested materials, being two of them etch-and-rinse adhesive systems (Adper Scotchbond Multi Purpose, 3M ESPE and Adper Single Bond 2, 3M ESPE) and two self-etching adhesive systems (Clearfil SE Bond, Kuraray and Optibond All-in-one, Kerr), were put in a concave glass container and the mass loss was measured in a analytical digital balance, after the application of the following techniques of solvent evaporation: air dry stream kept a distance of 10 cm from the tooth surface for 5 seconds (control technique) and diode laser irradiated continuously, perpendicularly and 1 cm distant from the tooth surface, in power outputs 1, 2 and 3 W for 5, 10 15, 20 and 25 seconds (experimental techniques). For each one of the 4 adhesive systems and in each one of the 4 evaporation techniques assessed, six series of monitoring were taken (n=6); b) to assess the temperature alteration in which the ten inferior central incisive teeth were selected (n=10), that had their root canals extended and filled with thermal paste. Afterwards, the root portion was submerged in thermal bath at 37°C and the thermocouple sensor, attached to a digital thermometer, was set up inside the pulp chamber. The diode laser was applied in the vestibular of the tooth crown, at 1 cm of distant from the surface and at 2 mm from the cementoenamel junction, in the power outputs 1, 2 e 3 W in a continuous mode and for the times 5, 10, 15 and 25 seconds. For each power output and in each tooth, five records of temperature as well as the record of the initial temperature, were carried out. The data on solvent evaporation rate (GE) and on the temperature variation were subjected to variance analysis and Tukey s test (α= 5%). Based on the values obtained from GE, the power output of 3 W for 25 seconds was that caused higher evaporation of the solvent, being better than the air dry stream technique to the adhesive systems Adper Scotchbond Multi Purpose e Adper Single Bond 2, and similar to the systems Clearfill SE Bond e Optibond All-in-One. Althogh thee was a significant statistical difference among the laser power outputs which were used and in all time intervals, the power output of 3W was the one which resulted in the highest average variation in temperature (3,27 °C), followed by 2 W (2,30 °C) and by 1 W (1,08 °C). Thus, the diode laser caused the solvent evaporation being dependent of the inherent characteristics of each adhesive system and, the parameters of diode laser irradiation employed in the current study didn t cause any damage to the pulp tissue. / Este estudo teve como objetivo avaliar in vitro a influência do laser de diodo na evaporação do solvente de sistemas adesivos e na variação da temperatura na câmara pulpar. Foi realizado em duas etapas, que consistiu em: a) avaliar o grau de evaporação do solvente (GE) pelo método gravimétrico, em que 10 μL de cada um dos materiais testados, sendo dois sistemas adesivos com condicionamento ácido (Adper Scotchbond Multi Purpose, 3M ESPE e Adper Single Bond 2, 3M ESPE) e dois sistemas adesivos autocondicionantes (Clearfil SE Bond, Kuraray e Optibond All-in-one, Kerr), foram dispensados em um recipiente de vidro côncavo e a perda de massa mensurada em uma balança digital, após a aplicação das seguintes técnicas de evaporação do solvente: jato de ar a uma distância de 10 cm por 5 segundos (técnica controle) e laser de diodo irradiado em modo contínuo, perpendicularmente e a uma distância de 1 cm, nas potências 1 , 2 e 3 W pelos tempos de 5, 10 15, 20 e 25 segundos (técnicas experimentais). Para cada um dos 4 sistemas adesivos e em cada uma das 4 técnicas de evaporação avaliadas, foram realizadas seis séries de monitoramento (n=6); b) avaliar a alteração de temperatura, em que foram selecionados 10 incisivos centrais inferiores (n=10), que tiveram os canais radiculares alargados e preenchidos com pasta térmica. Após, a porção radicular foi submersa em banho térmico a 37°C e o sensor termopar acoplado a um termômetro digital foi instalado no interior da câmara pulpar. O laser de diodo foi aplicado na vestibular da coroa dentária, a um 1 cm de distância da superfície e a 2mm da junção cemento esmalte, nas potências 1 , 2 e 3 W em modo contínuo e pelos tempos de 5, 10 15, 20 e 25 segundos. Para cada potência, em cada dente, foram realizados cinco registros de temperatura além do registro da temperatura inicial. Os dados do grau de evaporação (GE) e da variação de temperatura foram submetidos à análise de variância e teste de Tukey (α= 5%). Com base nos valores obtidos do GE, a potência de 3 W pelo tempo de 25 segundos foi a que acarretou maior evaporação do solvente, sendo superior a técnica do jato de ar para os sistemas adesivos Adper Scotchbond Multi Purpose e Adper Single Bond 2, e similar para os sistemas Clearfill SE Bond e Optibond All-in-One. Embora tenha ocorrido diferença estatística significativa entre as potências do laser empregadas e em todos os intervalos de tempo, a potência de 3 W foi a que acarretou a maior variação média de temperatura (3,27 °C), seguida da de 2 W (2,30°C) e 1 W (1,08 °C). Dessa forma, o laser de diodo provocou a evaporação do solvente sendo dependente das características inerentes a cada sistema adesivo e, os parâmetros de irradiação do laser de diodo empregados no presente estudo não causariam danos ao tecido pulpar.

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