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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.
151

Dimensionamento de plantas Biomass-to-Liquids para produção de óleo diesel sintético no Brasil / Sizing of Biomass-to-Liquid plants for synthetic diesel oil production in Brazil.

Aires Duarte 13 December 2013 (has links)
Há uma demanda global pelo abastecimento de combustíveis veiculares menos poluentes, tanto por questões energéticas quanto sócio-ambientais. Uma potencial alternativa, que traduz a possibilidade de um biocombustível sem as limitações da Primeira Geração, é a rota tecnológica conhecida como Biomass-to-Liquids (BTL) que, através da gaseificação e da síntese Fischer-Tropsch, possibilita a obtenção de biocombustíveis líquidos, como o óleo diesel sintético, provenientes da biomassa moderna, nesse estudo, a biomassa lignocelulósica. Para a produção em escala comercial de um biocombustível da Segunda Geração, um complexo planejamento e altos investimentos são demandados dado seu pioneirismo e ausência de histórico de mercado ou modelos precisos. Uma metodologia desenvolvida em 2006 pelo pesquisador Harold Boerrigter propõe o dimensionamento ideal de uma planta BTL a partir de uma planta Gas-to-Liquids (GTL); são aqui propostas correções e atualizações para esta metodologia, sugerindo-se uma curva capaz de apontar a influência da economia de escala em plantas BTL e uma fórmula para o cálculo estimado do Total Capital Investment (TCI) destas plantas até o momento o Brasil não dispõe de nenhuma planta que opere pela rota BTL. Segue-se com considerações sobre a oferta de resíduos florestais no território brasileiro e a constatação de que a mesma seria insuficiente como matéria-prima para sustentar grandes plantas BTL, fazendo-se necessário o emprego de culturas planejadas na forma de florestas energéticas. Uma vez feita tal análise, apresenta-se o histórico, desde sua concepção até o seu fechamento, da primeira planta a operar pela rota BTL e a produzir o designer fuel batizado de SunDiesel®: construída na Alemanha, a CHOREN Industritechnik contribui com sua experiência de anos e também com a tecnologia de gaseificação Carbo-V® para as pesquisas com os biocombustíveis sintéticos. Seu exemplo pode sinalizar um alerta com relação ao dispêndio de esforços em projetos desta natureza dadas as incertezas econômicas que circundam as fronteiras tecnológicas dos combustíveis da Segunda Geração. / There is a global demand for the supply of less polluting vehicular fuels as much by energy issues as socio-environmental. A potential alternative meaning the possibility of a biofuel without the limitations from the First Generation is the technological route known as Biomass-to-Liquids (BTL) which via gasification and the Fischer-Tropsch synthesis turns possible to obtain liquid biofuels such synthetic diesel oil from modern biomass, in this study, the lignocellulosic biomass. For commercial-scale production of a Second Generation biofuel, a complex planning and high investments are required given its pioneering and absence of market history or precise models. A methodology developed in 2006 by researcher Harold Boerrigter proposes the ideal sizing for a BTL plant assuming a Gas-to-Liquids (GTL) plant; here are proposed corrections and updates for this methodology, suggesting a curve able to point the influence of economy of scale in BTL plants and a formula for the calculation of an estimated Total Capital Investment (TCI) of these plants by the present time Brazil has no plant operating by BTL route. The research follows up with issues regarding forest residues provision in the Brazilian territory and conlcuding that the same would be insufficient as a raw material to sustain large BTL plants, making necessary the use of planned crops in the form of energy forests. Once made such analysis, it is presented the history since its beginning until its closing for the first plant to operate by the BTL route and to produce the designer fuel called SunDiesel®: built in Germany, the CHOREN Industritechnik contributes with its experience of years and also with the gasification technology Carbo-V® for researches with synthetic biofuels. Such example may indicates an alert regarding the expenditure of efforts on projects of this nature, given the economic uncertainties that surround the Second Generation fuels technological frontiers.
152

Obtenção de leveduras tolerantes aos inibidores do hidrolisado de bagaço de cana-de-açúcar mediante hibridação / Obtaining of yeasts for tolerance to inhibitors of sugarcane bagasse hydrolyzate by hybridization

Cristiane Silvello 27 June 2016 (has links)
O desenvolvimento de alternativas aos combustíveis fósseis como fonte de energia é uma prioridade global. A biomassa celulósica representa uma alternativa para satisfazer a procura de bicombustíveis renováveis. O bagaço de cana-de-açúcar é um abundante subproduto proveniente da produção atual de etanol no Brasil. Tal subproduto pode ser hidrolisado a fim de se obter açúcares fermentáveis para a produção do etanol de segunda-geração. Porém, no processo de pré-tratamento são gerados diversos inibidores como ácido acético, furfural e hidroximetilfurfural que causam efeitos adversos para a levedura no processo de fermentação alcoólica. A adição de melaço ao hidrolisado é uma forma de diminuir os efeitos dos inibidores no metabolismo das leveduras e também permite uma fermentação com maior teor alcoólico contribuindo para um balanço energético favorável da destilação, contribui também com o fornecimento de nutrientes minerais e orgânicos necessários a levedura para um processo empregando reciclo de células. Assim, objetivou-se selecionar linhagens de Saccharomyces cerevisiae com melhores características de multitolerância ao hidrolisado a partir de cruzamento direcionado e cruzamento massal seguido de evolução adaptativa. Para tal, linhagens S. cerevisiae industriais CAT-1, BG-1, PE-2 e SA-1 foram esporuladas e mediante micromanipulação foram obtidos 604 haploides, que foram avaliados quanto ao crescimento (DO570nm) em substrato constituído por hidrolisado e melaço. Os haploides selecionados (25) tiveram o \"mating type\" determinado permitindo a realização de 51 cruzamentos direcionados, gerando 398 zigotos, que foram igualmente avaliados para o crescimento no meio seletivo. Paralelamente, foram realizados cruzamentos massais, resultando em 7 diferentes populações, as quais foram submetidas à evolução adaptativa por 25 gerações, sendo que os isolados selecionados de cada cruzamento foram avaliados em fermentação com reciclo de células. Quatro linhagens se destacaram como superiores aos parentais, evidenciando que a estratégia utilizada permitiu a obtenção de linhagens de S. cerevisiae com maior tolerância aos estresses impostos por um substrato para produção do etanol de segunda geração. / The development of alternatives to fossil fuels as a source of energy is a global priority. Cellulosic biomass is an alternative to meet the demand for renewable biofuels. The sugarcane bagasse, an abundant byproduct generated from ethanol production in Brazil, can be hydrolysed to obtain fermentable sugars to produce second-generation ethanol. However, inhibitors produced in the pre-treatment process such as acetic acid, furfural and hydroxymethylfurfural, cause adverse effects to the yeast in the fermentation process. Addition of molasses in the bagasse hydrolyzate is one way to reduce the effects of inhibitors in the metabolism of yeast and also could allow fermentation with higher alcohol content contributing to a favorable energy balance in the distillation, as well as providing minerals and organic nutrients for the yeast. The main goal of this study was to select strains of Saccharomyces cerevisiae with better features of multi-tolerance to the bagasse hydrolyzate by directed crossing and mass mating followed by adaptive evolution. For that S. cerevisiae lineages CAT-1, BG-1, PE-2 e SA-1 were sporulated and 604 haploid cultures were obtained by micromanipulation and evaluated for growth (OD 570nm) in the substrate consisting of hydrolyzate and molasses. Selected haploids (25) were identified regarding their \"mating type\" (a and α) and used in. 51 directed crossings generating 398 zygotes, which were rescued by micromanipulation and also evaluated for growth in the same selective medium. Mass mating were performed with 7 different haploid populations from the parental strains, followed by an adaptive evolution for 25 generations. The selected zygotes were then subjected to fermentation trails with cell recycling, resulting in 4 strains with superior traits when compared with the parentals, allowing to conclude that the used strategy was successful in obtaining hybrids of Saccharomyces cerevisiae with increased profile of tolerance towards a substrate for second-generation ethanol production.
153

The experience of Canadian teachers who have taught first- or second-generation Chinese students in British Columbia, Canada: a phenomenological inquiry

Rennalls, Hayley 25 April 2019 (has links)
Extant research suggests the necessity for teachers to be culturally responsive to teach effectively to a diverse classroom. Extant research has also examined the perspectives of immigrant students in Western countries and the perspectives of teachers teaching to immigrant students. However, few studies have examined the perspectives of Canadian teachers lived experiences teaching first-or second-generation Chinese students. This qualitative study used a phenomenological approach to examine the experiences of six Canadian teachers who have taught first-or second-generation Chinese students and who have interacted with family members. The participants included four female and two male teachers with one teacher who taught in primary school and five teachers who have taught, and continue to teach in high school. The participants presently reside in British Columbia, Canada. The study’s data were gathered by semi-structured interviews, which were transcribed and analyzed to find common themes and the essence of the participants’ experiences. The study’s results indicated that Canadian teachers find teaching first-or second-generation Chinese students to be both positive and challenging. There are numerous differences between Chinese and Canadian preferences of learning, communicating, expectations, values, and perspectives of success, education, mental illness and learning challenges. The participants also provided recommendations for teachers and schools when teaching first- or second-generation Chinese students. / Graduate
154

Immigration and Identity Translation: Characters in Bharati Mukherjee’s Jasmine and Jhumpa Lahiri’s The Namesake as Translators and Translated Beings

Traister, Laura 01 May 2016 (has links)
Bharati Mukherjee’s 1989 novel Jasmine and Jhumpa Lahiri’s 2003 novel The Namesake both feature immigrant protagonists, who experience name changes and identity transformations in the meeting space of Indian and American cultures. Using the theory of cultural translation to view translation as a metaphor for identity transformation, I argue that as these characters alter their identities to conform to cultural expectations, they act as both translators and translated texts. Although they struggle with the resistance of untranslatability via their inability to completely assimilate into American culture, Jasmine and Gogol ultimately gain the ability to bypass the limitations of a foreigner/native binary and enter a space of negotiation and growth.
155

Bikulturalism och ackulturation : andragenerationsinvandrares erfarenhet av att leva med två kulturer

Forseth Åhman, Lisa January 2007 (has links)
<p>The aim of this paper was to examine the specific experience of being bicultural, what ackulturation strategy the person utilized and what influenced the use of this strategy. The findings were analyzed with the help of Pierre Bourdieu’s concepts of habitus and cultural capital. The empirical data was collected through qualitative interviews with four women of Chilean background, who either were born in or had been living in Sweden since childhood. The results of the interviews showed that all the respondents predominantly utilized the integration strategy, meaning that they participated in and felt a connection to both the Swedish and Chilean culture. However three of them had elements of the separation strategy and one had elements of the assimilation strategy. The respondent’s stories revealed that factors like parent’s encouragement and expectations, the Swedish society’s inaccessibility, type of residential area and knowing the Swedish language, had all influenced the use of a specific strategy. By being bicultural, the respondents had experienced the feeling of being an outsider and a pressure to assimilate, but still valued the access to two different cultures as a resource. The results can be interpreted as there being a reciprocal and significant influence between ackulturation strategy and cultural capital/habitus.</p>
156

Energy systems studied of biogas : Generation aspects of renewable vehicle fuels in the transport system

Magnusson, Mimmi January 2012 (has links)
The transport sector is seen as particularly problematic when concerns about climate change and dependency on fossil energy are discussed. Because of this, bioenergy is strongly promoted for use in the transport sector, both on a European level and nationally in Sweden. Even though bioenergy is considered one of the key solutions, it is generally agreed that both supply- and demand-side measures will be needed to achieve a change to a more sustainable transport system. One of the reasons for this is the limited availability of biomass, especially agricultural feedstocks competing with food or feed production. Woody biomass, however more abundant, is also exposed to tough competition from other sectors. In this thesis, the role of biogas as a vehicle fuel in a future sustainable transport system is discussed together with the prerequisites needed to realise such a transport system. Biogas is a biofuel that could be produced in several different ways: by anaerobic digestion, which is a first-generation production route, by gasification, which is a second-generation process, and by catalytic reduction of carbon dioxide, a third-generation technology. The main focus in this thesis is on biogas produced by anaerobic digestion and the results show that there is a significant potential for an increase compared to today’s production. Biogas from anaerobic digestion, however, will only be able to cover a minor part of the demand in the Swedish transport sector. Considering biogas of the second and third generations, the potential for production is more uncertain in a mid-term future, mainly due to competition for feedstock, the possibility to produce other fuels by these processes, and the present immaturity of the technology. The limited potential for replacing fossil vehicle fuels, either by biogas or other renewable fuels, clearly shows the need for demand-side measures in the transport system as well. This thesis shows the importance of technical and non-technical means to decrease the demand for transport and to make the transport as efficient as possible. The results show that both energy-efficient vehicles and behavioural and infrastructural changes will be required. Policies and economic incentives set by governments and decision-making bodies have a prominent role to play, in order to bring about a shift to a more sustainable transport system, however, measures taken on individual level will also have a great impact to contribute to a more sustainable transport system. / <p>QC 20121116</p>
157

Bikulturalism och ackulturation : andragenerationsinvandrares erfarenhet av att leva med två kulturer

Forseth Åhman, Lisa January 2007 (has links)
The aim of this paper was to examine the specific experience of being bicultural, what ackulturation strategy the person utilized and what influenced the use of this strategy. The findings were analyzed with the help of Pierre Bourdieu’s concepts of habitus and cultural capital. The empirical data was collected through qualitative interviews with four women of Chilean background, who either were born in or had been living in Sweden since childhood. The results of the interviews showed that all the respondents predominantly utilized the integration strategy, meaning that they participated in and felt a connection to both the Swedish and Chilean culture. However three of them had elements of the separation strategy and one had elements of the assimilation strategy. The respondent’s stories revealed that factors like parent’s encouragement and expectations, the Swedish society’s inaccessibility, type of residential area and knowing the Swedish language, had all influenced the use of a specific strategy. By being bicultural, the respondents had experienced the feeling of being an outsider and a pressure to assimilate, but still valued the access to two different cultures as a resource. The results can be interpreted as there being a reciprocal and significant influence between ackulturation strategy and cultural capital/habitus.
158

Parkinson's disease and depression clinical and neurobiological studies /

Pålhagen, Sven E., January 2009 (has links)
Diss. (sammanfattning) Stockholm : Karolinska institutet, 2009.
159

L’insertion professionnelle des Haïtiens de deuxième génération

Garcon, Cynthia 12 1900 (has links)
Ce mémoire porte sur l’insertion des Haïtiens de seconde génération sur le marché de l’emploi. L’insertion professionnelle est la condition principale permettant une intégration sociale. En effet, avoir un emploi a des répercussions au niveau économique, social et psychologique. Les écrits ont montré que les jeunes et particulièrement ceux faisant partie d’une minorité visible ont plus de difficulté à s’insérer sur le marché du travail. C’est dans cette optique que nous nous sommes penchés sur la condition des Haïtiens de deuxième génération. La littérature fait état des multiples difficultés sociales et économiques auxquelles est confrontée cette tranche de la population. Nous nous sommes donc intéressés aux caractéristiques de l’insertion professionnelle des ces Haïtiens de seconde génération. Nous avions comme objectif général d’analyser la trajectoire d’insertion de cette population sur le marché du travail. Notre démarche de type qualitatif s’est basée sur une série d’entrevues réalisées à l’hiver 2010 avec des hommes et des femmes Québécois d’origine haïtienne. Les thèmes abordés durant ces entrevues nous ont menés à des résultats différents de ceux recensés dans la littérature académique portant sur les Haïtiens de deuxième génération. En effet, nous avons rencontré des hommes et des femmes qui ont rencontré certains obstacles et qui continuent à faire face à des difficultés en lien avec leur vécu comme individu ayant une origine ethnique différente de celle de la majorité. Ces difficultés se manifestent également dans leur insertion en emploi. Cependant, cela n’a pas empêché ces enfants d’immigrants haïtiens de surmonter les obstacles et réussir leur intégration aux plans professionnel, économique et social. / This thesis focuses on the integration of second-generation Haitians on the job market. Integration on the job market is the main condition for social integration as being employed has impacts at the economical, social and psychological levels. The literature has shown that young people, particularly those belonging to visible minorities have more difficulty in entering the labor market. With this in mind, we examined the status of second-generation Haitians. The literature reports of multiple social and economic difficulties faced by this segment of the population. We are therefore interested in the characteristics of the experience of these second-generation Haitians in the workforce. Our main objective was to analyze the general trajectory of insertion of this population in the labor market. Our qualitative approach was based on a series of interviews conducted in the winter of 2010 with men and women of Haitian origin. Topics discussed during these interviews led to different results from those identified in the academic literature on second-generation Haitians. Indeed, we have met men and women who have encountered some obstacles and continue to face difficulties related to their experiences as individuals with an ethnic background different from that of the majority. These difficulties manifest themselves in their experience on the labor market. However, this has not prevented these children of Haitian immigrants to overcome obstacles and succeed in their integration at the professional, economic and social levels.
160

Wavelet-based multiscale simulation of incompressible flows / Simulation multi-échelle pour les écoulements incompressibles basée sur les ondelettes

Pinto, Brijesh 29 June 2017 (has links)
Cette thèse se concentre sur le développement d'une méthode précise et efficace pour la simulation des grandes échelles (LES) des écoulements turbulents. Une approche de la LES basée sur la méthode variationnelle multi-échelles (VMS) est considérée. La VMS applique aux équations de la dynamique des fluides une séparation d'échelles a priori sans recours à des hypothèses sur les conditions aux limites ou sur l'uniformité du maillage. Afin d'assurer effectivement une séparation d'échelles dans l'espace des nombres d'onde associé, nous choisissons d'utiliser les ondelettes de deuxième génération (SGW), une base polynomiale qui présente des propriétés de localisation spatiale-fréquence optimales. A partir de la séparation d'échelles ainsi réalisée, l'action du modèle sous-maille est limitée à un intervalle de nombres d'onde proche de la coupure spectrale. Cette approche VMS-LES basée sur les ondelettes est désignée par WAVVMS-LES. Elle est incorporée dans un solveur d'ordre élevé pour la simulation des écoulements incompressibles sur la base d'une méthode de Galerkin discontinue (DG-FEM) stabilisée pour la pression. La méthode est évaluée par réalisation de LES sur des maillages fortement sous-résolus pour le cas test du tourbillon de Taylor-Green 3D à deux nombres de Reynolds différents. / This thesis focuses on the development of an accurate and efficient method for performing Large-Eddy Simulation (LES) of turbulent flows. An LES approach based upon the Variational Multiscale (VMS) method is considered. VMS produces an a priori scale-separation of the governing equations, in a manner which makes no assumptions on the boundary conditions and mesh uniformity. In order to ensure that scale-separation in wavenumber is achieved, we have chosen to make use of the Second Generation Wavelets (SGW), a polynomial basis which exhibits optimal space-frequency localisation properties. Once scale-separation has been achieved, the action of the subgrid model is restricted to the wavenumber band closest to the cutoff. We call this approach wavelet-based VMS-LES (WAV-VMS-LES). This approach has been incorporated within the framework of a high-order incompressible flow solver based upon pressure-stabilised discontinuous Galerkin FEM (DG-FEM). The method has been assessed by performing highly under-resolved LES upon the 3D Taylor-Green Vortex test case at two different Reynolds numbers.

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