• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 5
  • 5
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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

Ecological Analysis of Hydrogen Production by Photovoltaic Electrolysis / Ekologisk analys av vätgasproduktion genom fotovoltaisk elektrolys

Dahlin, Oskar January 2014 (has links)
No description available.
2

Ecological and Exergetic analysis of Hydrogen Production in a Sugar-Ethanol Plant / Ekologisk och exergetisk analys av vätgasframställning i en socker-etanol anläggning

Colombaroli, Tulio January 2011 (has links)
This work aims an ecological and exergetic analysis of the hydrogen production by steam reforming of part of the ethanol produced in a sugar-ethanol plant. The Pioneiros Distillery, located in São Paulo, is used as model for this study. Three cases are described. In case 1 the plant produces energy only for domestic needs. A part of bagasse is not burned and it is stored. In Case 2, all available bagasse is used for production of steam. Part of the steam is used in the production process meeting the demand of the plant and the rest of steam is converted into electrical energy that can be sold at concessionaires. In Case 2 it is produced more energy than in Case 1. Case 3 includes the production of hydrogen by steam reforming of a part of the produced ethanol. Steam and energy for steam reforming is generated from combustion of bagasse. An exergetic analysis is performed. The exergy flows associated with the sugar-ethanol plant are calculated locating and quantifying the losses and irreversibility.  The ecological impact of use of the bagasse as fuel to generate thermal and electrical energy for the ethanol reformer was studied. The main pollutants that damage the atmosphere, namely: CO, CO2, NOx and PM have been taking into account. Carbon Dioxide emissions were calculated taking into account the carbon cycle (considering the absorption of carbon dioxide by the sugarcane during its growth), resulting in negative balance emissions, i.e., carbon dioxide was absorbed in higher amounts than emitted. The thermodynamics (ηsystem) and ecological (ε) efficiencies of Steam reforming of ethanol were calculated. The thermodynamic efficiency was 56% and the ecological efficiency was 80%. When the carbon cycle is taking into account the ecological efficiency is 90%. The incorporation of an ethanol reformer in a sugar-ethanol plant for hydrogen production is a very interesting option where environmental benefits are obtained. Problems related with the storage of bagasse are avoided because all the bagasse is burned for the production of steam and energy to the reformer. The amount of hydrogen that can be produced in Pioneiros Distillery could supply fuel for 68 buses with a range from 200 to 300 km per day.
3

Společenstva epigeických brouků plantáží rychle rostoucích dřevin a okolních biotopů / Communities of epigeic beetles (\kur{Coleoptera}) on the plantations of trees for energetic purposes

ZUKAL, Radim January 2013 (has links)
The aim of the study was to examine communities of epigeic beetles in the plantations of fast-growing trees (poplar clone Japanese J - 105 (Jap = - 105, Max - 4, Maxvier) and surrounding habitats (Zea mays L.). A cover of Zea mays L. was used as an area for comparison. Sampling was carried out in 2012 by using the method of epigeic beetles in pitfall traps (period from May to September). During the sampling, altogether 1054 specimens and 57 species of epigeic beetles were collected. In the area of fast-growing trees ?Na Vrbovecku? 528 specimens were collected which is many times more than in other researched areas. In the cover of Zea mays L. in the area "Na Vrbovecku" 293 specimens were collected and in the zone of fast-growing trees "U rybníka" 233 specimens were catched; notice the high similarity in the number of collected specimens. At all sites surveyed the expansive species (E) outnumbered the II relics. There were about 70% of expansive species in the cover of Japanese poplar found and in the cover of Zea mays L. there were about 90% of expansive species found. The number of more adaptable species- RII category- found in the cover of Japanese poplar was approximately 30% unlike the number of the same species found inside the Zea mays L. cover was only 12%. The rare species Xantholinus gallicus of the RI category was found in the plantations of fast-growing trees "U rybníka". The index of anthropogenic impact on communities (ISD) was very low in studied plots. In the Zea mays L.cover the index was only 6 points, unlike in the cover of Japanese poplar where the index reached 24 points. Yet all researched areas show high anthropogenic impact. Based on the obtained results (epigeic beetles), it seems that plantations of fast-growing trees have a positive impact on communities of epigeic beetles in cultural landscape. Since the research was always carried out on a farmed landscape, the impact of surrounding landscape on gained results is minimal and insignificant.
4

Uso do biogás para produção de biohidrogênio: eletrólise versus reforma a vapor / Use of biogas for hydrogen production: electrolysis versus steam reform

Paulino, Regina Franciélle Silva [UNESP] 08 March 2017 (has links)
Submitted by Regina Francielle Silva Paulino null (repaulino28@yahoo.com.br) on 2017-05-15T16:55:58Z No. of bitstreams: 1 Disssertação para repositório.pdf: 2094038 bytes, checksum: 627da6791c7083908510f6129d80d56f (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-05-16T14:35:09Z (GMT) No. of bitstreams: 1 paulino_rfs_me_guara.pdf: 2094038 bytes, checksum: 627da6791c7083908510f6129d80d56f (MD5) / Made available in DSpace on 2017-05-16T14:35:09Z (GMT). No. of bitstreams: 1 paulino_rfs_me_guara.pdf: 2094038 bytes, checksum: 627da6791c7083908510f6129d80d56f (MD5) Previous issue date: 2017-03-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho são estudados dois processos que utilizam biogás para obtenção do biohidrogênio. Inicialmente é analisado o processo de eletrólise da água, com o uso de energia elétrica gerada em conjunto motor de combustão interna/gerador (MCI) operando com biogás de aterro sanitário. Visando aproveitamento de calor dos gases de escape do MCI estuda-se o potencial de geração de energia térmica útil pela aplicação da técnica de cogeração. Considera-se dois casos: o primeiro para a produção de água quente em um trocador de calor, e o segundo, para a produção de água gelada em um sistema de refrigeração por absorção. Posteriormente é estudada a reforma a vapor de biogás para a produção de biohidrogênio, que utiliza também esse biocombustível para a geração de vapor superaquecido necessário ao processo de reforma. O objetivo é efetuar a análise energética de modo a determinar as eficiências dos processos, o potencial de produção de biohidrogênio, água quente ou água gelada, nos aterros sanitários da cidade de São Paulo. Também é efetuada análise de engenharia econômica para a determinação do custos da produção de biohidrogênio, água quente e água gelada, em US$/kWh. Esse estudo baseia-se em parâmetros tais como, investimento capital, custos de manutenção e operação dos equipamentos, período equivalente de utilização e período de amortização de capital. Em fase final, foram realizados estudos de impactos ambientais para a determinação das eficiências ecológicas dos processos de produção de biohidrogênio (reforma a vapor e eletrólise), considerando as emissões de poluentes, o dióxido de carbono equivalente e os indicadores de poluição. Como conclusões, tem-se que considerando a disponibilidade de biogás da cidade de São Paulo, existe potencial para a produção de biohidrogênio, e que o processo de reforma a vapor do biogás apresenta maior nível de eficiência sob o ponto de vista termodinâmico. Quando se considera a eletrólise incorporando a técnica da cogeração com a produção simultânea de eletricidade e água quente ou água gelada, observa-se aumento da eficiência energética do processo. A reforma a vapor do biogás, também se mostra mais atrativa economicamente de acordo com os parâmetros considerados. Sobre o ponto de vista ambiental, o processo de eletrólise com produção de água gelada apresenta maior eficiência ecológica, seguidos do processo de produção de água quente, reforma a vapor e somente eletrólise. / In this work is studied two processes to obtain hydrogen using biogas. Initially is analyzed the process of electrolysis of water, with the use of electricity generated in conjunction with an internal combustion engine / generator (ICE) operating with landfill biogas. generated by an internal combustion engine/generator operating with landfill biogas, is analyzed. In order to take advantage of the exhaust gases from the combustion of biogas, the potential of cogeneration is studied, another two cases are considered. The first one studies the production of hot water in the heat exchanger and the second analyzes the use of absorption refrigeration system to produce cold water. Subsequently it is studied the steam reform of biogas for the production of hydrogen, which is constituted of biogas burning for the generation of superheated steam used in the conversion of the fuel input. The objective is to make the energy analysis in order to determine the efficiency of the processes and the potential of producing hydrogen, hot water or ice water in the landfills of the city of São Paulo using the biogas generated. An economic engineering analysis to determine the production hydrogen cost, hot water and ice water, in US$/kWh, based on capital investment, maintenance and operation costs, equivalent period of use and payback. In the final phase, environmental study method is applied to determine the ecological efficiencies of the hydrogen production processes using biogas, considering the emissions of pollutants, carbon dioxide equivalent and pollution indicator. As a conclusion, considering the hydrogen production capacity and the biogas availability of the city of São Paulo, the process of steam reforming of the biogas is more thermodynamically efficient. When considering the electrolysis incorporating the cogeneration technique with the simultaneous production of electricity and hot water or cold water, it is observed an increase in the energy efficiency of the process. The steam reform of the biogas is more attractive economically according to the considered parameters. From the environmental point of view, the process of electrolysis with the production of cold water presents greater ecological efficiency, followed by the process of hot water production, steam reforming and only electrolysis.
5

Etude des déterminants géographiques et spatiaux de la qualité de vie liée à la santé en France / Geographic and spatial determinants of health-related quality of life in France

Audureau, Etienne 19 December 2012 (has links)
CONTEXTE : La France est caractérisée par l’existence de fortes disparités socioéconomiques et géographiquesde l’état de santé, le plus souvent objectivées par des indicateurs objectifs de morbidité et de mortalité. Ladistribution territoriale des mesures de santé perçue comme la qualité de vie liée à la santé (QdVLS) reste malconnue en population générale. Une meilleure connaissance de la répartition et des déterminants – en particuliercontextuels - de ces indicateurs subjectifs permettrait de mieux comprendre leur signification par rapport auxindicateurs objectifs et d’apprécier l’intérêt spécifique de leur suivi en population générale.OBJECTIFS : Les objectifs de cette recherche étaient [1] d’étudier l’existence de disparités spatiales de QdVLSdans la population française et d’analyser leur évolution dans le temps, [2] d’étudier les déterminants de laQdVLS à la fois individuels et contextuels dans le cadre d’une analyse multiniveau, et [3] d’évaluer lesassociations écologiques entre QdVLS et mortalité ultérieure à cinq ans d’intervalle.MATERIEL ET METHODES : Les données issues de deux enquêtes transversales nationales représentatives ont étéexploitées : l’enquête Décennale 2003 de l’Insee pour l’ensemble des travaux menés (N=22 743 [1 et 3] ; N=16 732 [2]) et l’enquête Sofres 1995 pour l’analyse de l’évolution temporelle de la QdVLS (N=3 243 [1]). Lequestionnaire utilisé dans les deux enquêtes était le SF-36. [1] Des modèles de régression linéaire multiple àeffets fixes avec recherche d’interactions ont été réalisés pour l’analyse de l’évolution temporelle. [2] L’analysemultiniveau des déterminants contextuels de la QdVLS s’appuyait sur des modèles à effets mixtes, afind’explorer une chaine causale incluant des déterminants aux niveaux individuel, du ménage, de l’unité urbaine etrégional, d’ordre démographique, socioéconomique ou intégrant la notion contextuelle plus complexed’attractivité (taux migratoire, désindustrialisation). [3] Les données de mortalité étaient issues de la statistiquenationale des décès élaborée annuellement par le CépiDc. Des modèles de régression binomiale négative ont étéréalisés pour l’analyse des associations écologiques au niveau régional entre QdVLS en 2003 et mortalitéultérieure (court terme [2003-2005] ; à 5 ans [2007-2009]) et en stratifiant sur le sexe, l’âge et les causesspécifiques de décès.RESULTATS PRINCIPAUX : [1] Une diminution significative de la QdVLS était observée entre 1995 et 2003affectant tous les groupes sociodémographiques et suggérant la possibilité d’un accroissement des disparités pourles catégories les plus fragiles de la population. [2] De fortes disparités régionales de QdVLS étaient retrouvées,persistant après ajustement sur les caractéristiques socioéconomiques individuelles. L’analyse multiniveaupermettait d’identifier des processus de médiation impliquant les variables contextuelles de désindustrialisation,le taux d’accroissement migratoire, le taux d’abstention aux élections, et les comportements liés à la santé. Desinteractions inter-niveaux et intra-régionales étaient identifiées. [3] Des associations écologiques significativesétaient retrouvées au niveau régional entre QdVLS et mortalité à cinq ans d’intervalle, persistant aprèsajustement sur le niveau socioéconomique. Des relations spécifiques étaient observées après stratification surl’âge, le genre, les causes spécifiques de décès ; le caractère prédictif de la QdVLS variait selon le délai plus oumoins court entre mesure de la QdVLS et mortalité. / BACKGROUND: Wide social and geographical disparities are reported in France for morbidity and mortalityindicators. Less is known regarding the spatial distribution in general population of self-rated health (SRH) andhealth-related quality of life (HRQoL). Improving the knowledge of the contextual determinants of HRQoLwould help towards a better understanding of their meaning and interest in general population when it comes tocompare with classical objective indicators.OBJECTIVES: The objectives were [1] to assess existing spatial disparities of HRQoL in French generalpopulation and to investigate their evolution in time, [2] to determine individual and contextual determinants ofHRQoL and [3] to explore the ecological associations between HRQoL and subsequent mortality five years later.METHODS: Data were drawn from two large representative cross sectional surveys: the Insee Decennial HealthSurvey led in 2003 (N=22 743 [study 1 and 3] ; N= 16 732 [2]) and the Sofres health survey led in 1995(N=3243 [1]).The MOS SF-36 questionnaire was used in both surveys. [1] Fixed effects linear models combinedwith interaction tests were used for assessing time trends. [2] Mixed effects linear models were used for themultilevel analysis, exploring a causal pathway including individual and macrolevel factors (household, urbanunit and region) assessing demographics, socioeconomics, and features related to the notion of areaattractiveness (deindustrialization, net migration rates). [3] Mortality data were drawn from the French nationalstatistics of mortality (CepiDc-Inserm). Negative binomial regression models were performed to identifyecological associations at the region level between HRQoL recorded in 2003 and subsequent mortality (shortterm [2003-2005]; 5-years later [2007-2009]), stratifying on age, gender and specific causes of death.MAIN RESULTS: [1] A significant decrease in HRQoL was observed between 1995 and 2003, affecting allsociodemographic categories and suggesting likely widening disparities in the most fragile categories. [2]Regional HRQoL disparities were found, persisting after adjusting on socioeconomic individual characteristics.Multilevel analysis showed some evidence for mediation involving contextual factors like deindustrialization,net migration rates, voter abstention rate and health-related behaviors. Cross-level interactions were found aswell. [3] Significant ecological associations were identified at the region level between HRQoL and mortalityfive years later, persisting after adjusting on deprivation. Specific relationships were observed after stratifying onage, gender, specific causes of death; the predictive ability of HRQoL for mortality was varying depending onthe mortality period considered for analysis.CONCLUSIONS: Our results highlight the interest in assessing HRQoL at the population level and in exploringthe contextual determinants at play. Systematic inclusion of validated and multidimensional HRQoLquestionnaires should be supported in national surveys, so as to improve our knowledge of long term temporaltrends in HRQoL, to promote an increased use of contextual multilevel analyses using such data, and eventuallyto help better identifying sub-groups at risk and optimizing public health interventions.

Page generated in 0.0634 seconds