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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.
81

Avaliação e melhoria do poder calorífico de biogás proveniente de resíduos sólidos urbanos

Okamura, Layssa Aline 27 March 2013 (has links)
CNPq, CAPES / Com o novo cenário mundial voltado às práticas sustentáveis está se tornando um foco importante de pesquisa a busca por tecnologias que utilizem recursos renováveis e que diminuam ou eliminem a produção de contaminantes e poluentes ambientais em processos de obtenção de energia. A partir disto, esta dissertação focou a purificação de biogás produzido em aterro sanitário desativado na cidade de Curitiba (Caximba) para avaliar a sua utilização na produção de energia, melhorando o seu poder calorífico. Durante o estudo foi desenvolvido um calorímetro para determinar o poder calórico do biogás. Para comparação dos resultados foram feitas análises das concentrações de metano, dióxido de carbono, amônia e gás sulfídrico através de um kit comercial para análise de biogás. As coletas e análises do biogás foram realizadas em dois locais no aterro com diferentes idades de resíduo confinado. Foram identificadas diferenças significativas nos teores de metano e gás sulfídrico nos gases estudados. A purificação do biogás foi realizada através da aplicação de colunas recheadas com solução de acetato de chumbo, solução de hidróxido de sódio, sílica gel e carvão ativo. A purificação atingiu até 73% de teor de metano. A eficiência de purificação foi maior ainda para o tratamento do biogás com menor teor de metano (23%), aonde a eficiência chegou a 145% em relação ao valor inicial. A utilização de indicadores de saturação mostrou-se bastante interessante no uso das colunas de purificação, pois a saturação podia ser determinada visualmente. Uma vez calculadas os percentuais de purificação do biogás foram estimadas a produção de energia, a venda da mesma com geração de receita e os custos relacionados ao processo de purificação. Através destas estimativas verificou-se que a renda da venda de energia elétrica produzida seria suficiente para arcar com os custos da aplicação do processo de purificação. / Given the new global scenario turned to sustainable practices it is becoming a major focus of research the search for technologies that use renewable resources reducing or eliminating the production of environmental pollutants and contaminants in energy production process. This project focused on the purification of biogas in Curitiba’s closed landfill of to evaluate its use for energy production, aiming to improve its calorific value. During the study, a calorimeter was developed and optimized to evaluate the calorific value of the biogas. For results comparison, analyses were made to determinate the concentrations of methane, carbon dioxide, ammonia and hydrogen sulfide using a commercial kit for analysis of biogas. Landfill biogas sampling and analysis were conducted at two sites where the waste was confined at different times. We identified significant differences in the levels of methane and hydrogen sulfide in the analyzed gases. Biogas purification was performed by applying columns packed with lead acetate solution, sodium hydroxide solution, silica gel and activated carbon. A higher efficiency of biogas purification (145%) was attained with a lower initial methane content (23%). The use of saturation indicators proved to be very interesting in the use of purification column, since the saturation could be determined visually. With the purification percentage calculated, it was estimated the energy production, revenue through energy sale and costs related to the purification process. Through this estimation it is possible to note that the profits from the electricity produced sale would be sufficient to meet the costs of the purification process application.
82

Études de la violation de CP dans les désintégrations B0 -> DK*0 et des performances du système de déclenchement hadronique avec le détecteur LHCb au CERN / CP violation studies on the B0 -> DK*0 decays and hadronic trigger performance with the LHCb detector at CERN

Martin Sanchez, Alexandra 25 June 2013 (has links)
Dans le Modèle Standard de la physique des particules, le mécanisme Cabibbo-Kobayashi-Maskawa (CKM) décrit le phénomène du mélange des quarks. De ses paramètres, l'angle gamma est celui connu avec la moins grande précision. Les mesures directes donnent une incertitude d'environ 15º, importante comparée à celle sur la valeur extraite des ajustements globaux, de 3º. Pour vérifier la cohérence du Modèle Standard, gamma doit être mesuré précisément. Cela est possible en utilisant des processus au niveau des arbres, où seules des contributions du Modèle Standard sont attendues, ou avec des processus impliquant des boucles, qui peuvent être sensibles à des effets au-delà. Des différences entre la mesure de gamma avec des diagrammes en arbres et avec des boucles pourraient être donc une indication de nouvelle physique. Cette thèse présente la première mesure des observables CP dans la désintégration B0 -> DK*0. Celle-ci est sensible à gamma du fait de l'interférence entre l'amplitude des diagrammes b -> u et b -> c, au niveau des arbres. L'asymétrie CP dans le mode B0 -> D(K+K-)K*0 et le rapport des largeurs partielles avec B0 -> D(K+pi-)K*0 sont mesurés avec 1 /fb de données récoltées par l'expérience LHCb en 2011,A_KK_d = -0,452 +/- 0,230 +/- 0,025 = A_CP+,R_KK_d = 1,360 +/- 0,366 +/- 0,075 = R_CP+. L'asymétrie CP du mode supprimé B0 -> D(K-pi+)K*0 et le rapport des largeurs partielles avec le favorisé B0 -> D(K+pi-)K*0 sont mesurés avec 3 /fb de données récoltées en 2011 et 2012,A_sup_d = -0,094 +/- 0,318 = A_ADS,R_d = 0,075 +/- 0,023 = R_ADS. Les études réalisées sur le système de déclenchement hadronique de l'expérience LHCb sont aussi présentées. / In the Standard Model of particle physics, the Cabibbo-Kobayashi-Maskawa (CKM) mechanism describes the quark mixing effect. The CKM gamma angle is one of the parameters of the Standard Model that are known less accurately. Direct measurements give an uncertainty of around 15º, large with respect to the uncertainty on the value extracted from global fits, of 3º. In order to test the Standard Model consistency, the gamma angle needs to be measured precisely. This can be done using processes at the tree-level, where only Standard Model contributions are expected, or using processes involving loop diagrams, which can be sensitive to physics beyond the Standard Model. Differences in the gamma measurement from tree and loop diagrams would be an indication of new physics. This thesis presents the first measurement of the CP observables in the B0 -> DK*0 decay. Sensitivity to gamma arises from the interference of the b -> u mediated amplitude with the b -> c one, at the tree-level. The CP asymmetry of the B0 -> D(K+K-)K*0 mode and the partial width ratio of this channel with respect to B0 -> D(K+pi-)K*0 are measured using 1 /fb of data collected by the LHCb experiment in 2011,A_KK_d = -0.452 +/- 0.230 +/- 0.025 = A_CP+,R_KK_d = 1.360 +/- 0.366 +/- 0.075 = R_CP+. The CP asymmetry of the suppressed B0 -> D(K-pi+)K*0 mode and the partial width ratio with respect to the favoured B0 -> D(K+pi-)K*0 are measured using the total 3 /fb of data collected in 2011 and 2012,A_sup_d = -0.094 +/- 0.318 = A_ADS,R_d = 0.075 +/- 0.023 = R_ADS. In addition, the studies performed on the hardware hadronic trigger of the LHCb experiment are also presented.
83

3D Thermal Mapping of Cone Calorimeter Specimen and Development of a Heat Flux Mapping Procedure Utilizing an Infrared Camera

Choi, Keum-Ran 02 February 2005 (has links)
The Cone Calorimeter has been used widely for various purposes as a bench - scale apparatus. Originally the retainer frame (edge frame) was designed to reduce unrepresentative edge burning of specimens. In general, the frame has been used in most Cone tests without enough understanding of its effect. It is very important to have one - dimensional (1D) conditions in order to estimate thermal properties of materials. It has been implicitly assumed that the heat conduction in the Cone Calorimeter is 1D using the current specimen preparation. However, the assumption has not been corroborated explicitly to date. The first objective of this study was to evaluate the heat transfer behavior of a Cone specimen by examining its three - dimensional (3D) heat conduction. It is essential to understand the role of wall lining materials when they are exposed to a fire from an ignition source. Full - scale test methods permit an assessment of the performance of a wall lining material. Fire growth models have been developed due to the costly expense associated with full - scale testing. The models require heat flux maps from the ignition burner flame as input data. Work to date was impeded by a lack of detailed spatial characterization of the heat flux maps due to the use of limited instrumentation. To increase the power of fire modeling, accurate and detailed heat flux maps from the ignition burner are essential. High level spatial resolution for surface temperature can be provided from an infrared camera. The second objective of this study was to develop a heat flux mapping procedure for a room test burner flame to a wall configuration with surface temperature information taken from an infrared camera. A prototype experiment is performed using the ISO 9705 test burner to demonstrate the developed heat flux mapping procedure. The results of the experiment allow the heat flux and spatial resolutions of the method to be determined and compared to the methods currently available.

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