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Santos, Rodrigo Alves dos. "Estudo da viabilidade técnica e econômica de produção de petróleo sintético offshore a partir de rejeito rico em CO2." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-11072014-020823/.
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A descoberta de uma nova província petrolífera, conhecida como pré-sal, localizada no litoral brasileiro, representa um novo marco na produção de petróleo mundial. Dentre os vários desafios encontrados para exploração e produção dessa região, a presença de CO2 em grandes concentrações nos fluidos de alguns desses reservatórios tem sido um dos desafios de maior relevância para as empresas que exploram e produzem nessa área (FORMIGLI, 2007). Uma forma alternativa de sequestro do CO2 retirado do gás natural é a sua utilização como matéria prima ou co-alimentação para a síntese de produtos químicos, em especial aqueles com grande demanda de mercado. Um dos produtos que podem ser obtidos indiretamente a partir do CO2 é o petróleo sintético, produzido pelo processo conhecido como Gas-to-Liquids, ou GTL. Neste trabalho foi analisada a viabilidade técnica, econômica e potencial de captura de CO2, da produção de petróleo sintético, pelo processo GTL, offshore, a partir de dióxido de carbono (CO2) e metano (CH4), presentes na corrente de rejeito do tratamento do gás processado em uma plataforma de produção de petróleo e gás, através das reformas seca e a vapor, seguida da síntese Fischer-Tropsch. A partir de dados de literatura e com uso de simulador comercial de processos, a simulação do processo foi desenvolvida e diferentes alternativas para reaproveitamento das correntes residuais do processo foram analisadas, incluindo o reciclo e a queima dos efluentes combustíveis, assim como foram aplicadas técnicas de integração energética, otimização e análise econômica de processos. Os resultados indicaram que o processo, mássica e energeticamente integrado, na condição de menor emissão de CO2 e maior retorno financeiro, produziu petróleo sintético de forma técnica e economicamente viável. Os resultados indicaram ainda que o processo GTL, com as tecnologias utilizadas, não é indicado como método de captura de CO2 devido o fato de a geração desse componente para a produção de petróleo sintético ser duas vezes maior que a quantidade alimentada.The discovery of a new oil province known as pre-salt, located in the Brazilian coast, represents a new frontier in the world\'s oil production. Among other challenges involved in the exploration and production in that region, the CO2 concentration at high levels in the fluids of some of those reservoirs has been the most relevant challenge for the companies that explore and produce in that area (FORMIGLI, 2007). An alternative to sequestering the CO2 extracted from natural gas is using it as a supply of raw material or as an input to the synthesis of chemical products, especially those with great market demand. One of the products that can be obtained indirectly from CO2 is synthetic fuel, produced by the process known as Gas-to- Liquids, or GTL. In this work the technical, economical and potential feasibility of CO2 capture is analyzed, as well as the production of synthetic fuel using the GTL process, offshore, from carbon dioxide (CO2) and methane (CH4), found in the waste chain of the gas treatment in an oil and gas production platform, through dry and steam reforming, followed by Fischer-Tropsch synthesis. Thus, based on literature data and on the use of a commercial process simulator, the simulation of the suggested process was developed and different alternatives to the reutilization of the waste chains were analyzed, including the recycling and burning of some effluent streams. Techniques of energetic integration, optimization and economic analysis of process have also been applied. The results indicated that the process, mass and energy integrated in the condition of lower CO2 emissions and greater financial return, produced synthetic oil in a technically and economically feasible way. The results also indicated that the GTL process, with the technologies used, is not suitable as a method for CO2 capture due to the fact that the generation of this component for the production of synthetic oil is two times greater than the amount fed.
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Wang, Xiaonian. "Computer simulation of GTL and various problems in thermodynamics." Texas A&M University, 2003. http://hdl.handle.net/1969.1/2210.
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This dissertation intends to provide new tuning techniques for several simple cubic equations of state (EOS) to improve their accuracy in calculating fluid phase equilibrium. It also provides graphical tools to predict some phase equilibrium phenomena from activity coefficient models. Finally, it presents simulation results for a new gas-to-liquids process.
Saturation Properties for Fluids: By deriving a new identity linking the heat of vaporization for pure components to the EOS, we are able to find new expressions for the two constants a & b in the EOS. These new expressions then allow tuning of both constants a and b to experimental saturation properties at subcritical temperatures. These new tuning procedures prove effective to the point where the simpler Redlich-Kwong EOS provides better results with our procedure than does the usually superior Peng-Robinson EOS with conventional procedures.
Activity Coefficient Models: This dissertation shows the flexibility of four activity coefficient models in the prediction of three fluid phase equilibrium phenomena. From these models we successfully developed new graphs that allow one to identify the presence of any of the three phenomena by visual inspection without performing a complex calculation as seen in current texts.
Remote Natural Gas: This dissertation presents simulation results of a new gas-to-liquids process which converts natural gas to liquid transportation fuels.
Based on the assumption of adiabatic reactions, our simulation results show that methane conversion increases with higher reaction temperature and longer residence times. Hydrogen can both inhibit methane decomposition and reduce coke formation. The rich components in the natural gas are found to decompose very fast and they have a vast quenching effect on the whole reactions. Recycling of unreacted methane also increases overall methane conversion. Finally, our simulator provides very close prediction of the experimental results from a pilot plant. Thus, we conclude that the simulation work is basically successful in fulfilling the goal of this research.
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Gerry, Michael J. "Two-dimensional inverse scattering based on the GTD model /." The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487946103567201.
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Quintero, Soltero Oscar. "Microstructural characterization of overaged GTD-111 HP turbine buckets." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Asari, Satoshi. "Evaluation of the GTL technology for use in the *T Network." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/36511.
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Bao, Buping. "Simulation, integration, and economic analysis of gas-to-liquid processes." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3131.
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Presotto, Alice. "Efeitos de campos magnéticos externos e de correntes de transporte na dinâmica de vórtices em uma constrição mesoscópica /." Ilha Solteira, 2017. http://hdl.handle.net/11449/151624.
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Orientador: Rafael ZadorosnyResumo: Com o desenvolvimento científico, a fabricação de materiais em escalas nano e submicrométricas tornou-se uma realidade. Nos estudos teóricos e experimentais de materiais supercondutores, tais sistemas são denominados de mesoscópicos, e possuem tamanhos da ordem dos seus comprimentos característicos, i.e., λ(T) e ξ(T). Nessas escalas, a dinâmica de vórtices é fortemente dominada por efeitos de confinamento. Dessa forma, a investigação de suas características tem importância fundamental para o desenvolvimento e aplicação desses materiais de forma eficaz. Assim, neste trabalho foram estudados os efeitos da passagem de uma corrente de transporte por uma constrição de tamanhos mesoscópicos, que foi produzida inserindo dois defeitos (normalizando 0<ψ<1 dentro do defeito) nas bordas opostas do sistema. Para tal, simulamos amostras supercondutoras mesoscópicas na presença de correntes de transporte e de campos magnéticos solucionando a equação generalizada de Ginzburg-Landau dependente do tempo (GTDGL). Sem campo magnético aplicado, os pares de vórtices cinemáticos são formados nos defeitos e se aniquilam no centro da amostra. Por outro lado, quando um baixo campo magnético é aplicado, produz uma assimetria na distribuição das correntes supercondutoras. Então, apenas o vórtice cinemático é formado em uma borda da amostra e a deixa pela lateral oposta. Contudo, antes de deixar o sistema, o vórtice cinemático experimenta um efeito de barreira superficial, que causa uma diminuição em su... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: With the scientific development, the fabrication of materials at nano and sub-micrometer scales become a reality. In theoretical and experimental study of superconducting materials, such systems are called mesoscopic and have sizes of the order of their characteristic lengths, i.e., λ(T) and ξ(T). In these scales, the vortex dynamics is strongly dominated by confinement effects. In this way, the investigation of their characteristics have fundamental importance for the development and application of these materials effectively. Then, in this work we studied the effect of a transport current flowing through a mesoscopic constriction, which was produced by inserting two defects (normalizing 0<ψ<1 inside the defect) on the opposite edges of the system. The mesoscopic superconducting samples were simulated in the presence of transport currents and applied magnetic fields by solving the time-dependent Ginzburg-Landau equation in its generalized form (GTDGL). At zero applied magnetic field, kinematic vortex-antivortex pairs are formed at the defects and annihilate at the center of the sample. On the other hand, small external magnetic fields produce an asymmetry in the distribution of the superconducting currents. Then, only one kinematic vortex is nucleated in one of the borders of the sample and leaves it by the opposite side. However, before leaves the system, the kinematic vortex experiences a surface barrier effect, which causes a decrease in its velocity. The results obtained... (Complete abstract click electronic access below)
Mestre
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Presotto, Adriana Guirao. "Resposta magneto-elétrica de nanofitas supercondutoras granulares : simulações utilizando o formalismo de Ginzburg-Landau dependente do tempo /." Ilha Solteira, 2020. http://hdl.handle.net/11449/192560.
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Orientador: Rafael ZadorosnyResumo: Correntes de transporte interagem com os vórtices de Abrikosov nos supercondutores do tipo II via força de Lorentz (FL), o que pode resultar em seu movimento. Esse movimento ocorrerá se FL suprimir a força de pinning (FP) [4,6], que mantém os vórtices ancorados, tais como defeitos e orifícios artificiais nas amostras. Nos casos em que FL >> FP, os vórtices se movem livremente e experimentam apenas resistência viscosa devido à sua interação com o condensado supercondutor. Esse estado de movimento é conhecido como flux flow (FF). Assim, no presente trabalho, estudamos a dinâmica dos vórtices em uma fita supercondutora com tamanhos laterais de 10 ξ(0) x 70 ξ(0), com seis grãos espaçados por um supercondutor de menor Tc, i.e., um weak-link (WL). Além disso, em cada grão foram considerados quatro defeitos da mesma natureza que os WL’s, simulando defeitos intrínsecos. Para tal estudos, as equações generalizadas de Ginzburg-Landau dependentes do tempo (GTDGL) foram solucionadas numericamente. Assim, foram considerados três valores diferentes de campos magnéticos externos, i.e., Hap = 0,1 Hc2(0), 0,3 Hc2(0) e 0,5 Hc2(0), e densidade de correntes de transporte de intensidade que variou em passos de 0,005J0. Observou-se que a intensidade de Hap, influencia diretamente nos regimes de movimento, onde para Hap = 0,1 Hc2(0) foi verificado apenas o FF intergranular e uma dinâmica mais duradoura. Já para Hap = 0,3 Hc2(0) e 0,5 Hc2(0) foram observados dois regimes de movimento, o flux flow (F... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Transport currents interact with Abrikosov vortices in type II superconductors via Lorentz force (FL), which can result in their motion. Such movement will occur if FL suppresses the pinning force (FP) [4,6], which keeps vortices trapped, such as defects and artificial holes in the samples. In cases where FL >> FP, the vortices move freely and experience only a viscous resistance due to their interaction with the superconducting condensate. This state of motion is known as flux flow (FF). Thus, in the present work, we studied the vortex dynamics a superconducting tape with lateral sizes of 10 ξ(0) x 70 ξ(0), with six grains spaced by a smaller Tc superconductor, i.e., a weak-link (WL). In addition, in each grain, four defects of the same nature as the WL's were considered, simulating intrinsic defects. For such studies, the generalized time-dependent Ginzburg-Landau equations (GTDGL) were solved numerically. Thus, three different values for the external magnetic field were considered, i.e., Hap = 0.1 Hc2(0), 0.3 Hc2(0) and 0.5 Hc2(0), and density of transport currents of intensity that varied in steps of 0,005 J0. It was observed that the intensity of Hap directly influences the motion regimes, where for Hap = 0.1 Hc2 (0) it was verified only the intergranular FF and a longer dynamics. For Hap = 0.3 Hc2(0) and 0.5 Hc2(0), two motion regimes were observed, the inter and intragranular FF. However, there was a faster destruction of the superconductor (SC). It was also found that... (Complete abstract click electronic access below)
Mestre
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COSTA, LETICIA DE ALMEIDA. "VALUATION OF GTL PROJECT: A REAL OPTION APLICATION WITH MEAN REVERSION MODEL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10096@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO Presente trabalho tem como objetivo analisar a viabilidade econômica de uma planta XTL usando a teoria das Opções Reais. Esta metodologia é a mais adequada para avaliar a capacidade que este tipo de projeto dispões de trocar de input e/ou output, ou seja, eleger a cesta que maximiza o resultado final, de acordo com cada cenário. Essa política ótica permite avaliar a construção de uma planta com flexibilidades, com o investimento ocorrendo em um ambiente de incerteza, onde os preços (fatores de incerteza) serão considerados estocáticos e seguirão um Movimento de Reversão à Média. Os cálculos numéricos serão feitos através da simulação de Monte Carlo. A tecnologia, designada XTL, está dividida em duas etapas: um processo de gaseificação seguido de um processo GTL (gás-to- liquid). A gaseificação permite transformar sólidos, líquidos e gases em gás de síntese, que será usado como input do GTL. Já o GTL possibilita transformar o gás de síntese em líquidos de alta qualidade, tais como nafta, diesel, parafinas e lubrificantes. Por associação, esta dissertação faz parte de um projeto que visa aplicar a teoria de Opções Reais na avaliação de investimentos em Pesquisa e Desenvolvimento (P&D), com a finalidade de valorar e considerar as flexibilidades inerentes a este tipo de projeto.
The present work has objective to analyze the investiment of a XTL plant using the Real Options Theory. This methodology is adjusted to evaluate the capacity that this project has to changes its input and/or output, in other words, to elect the option that maximizes payoff, in accordance with each scenario, allowing to evaluate the construction of a plant with flexibilities with the investiments happening in an environment of economical and/or technical uncertainties, where the prices (uncertainty factors) are stochastic and will follow the Mean Reversion Model, calculated by the Monte Carlo Simulation. The XTL technology is divided in two stages: a gasification process followed by a GTL (gas-to-liquid) process. The gasification process allows you to transform solids, liquids and gases into synthesis gas, that will be used as input of the GTL. The GTL makes possible to transform the syntesis gas into high quality liquids, such as naphtha, diesel, paraffins and lubrificants. This work is part of a project, with the objective to apply the Real Options Theory in the evaluation of investiments in Research and Development (R&D), aiming to price and consider the flexibilities that are inherent to this project.
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Karabanova, Anastasiya. "The Effectiveness of Small-scale GTL Technologyin Remote Small Fields of Russia." Thesis, KTH, Energiteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-210216.
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In the Thesis, the problem of associated petroleum gas flaring both in Russia and in the world is revealed. The analysis of associated petroleum gas utilization methods in respect to the small remote oil fields is carried out. The Thesis shows the perspective of creating low and medium power autonomous installations for energy supply to the oil facilities in the remote areas with poorly developed energy infrastructure by processing associated petroleum gas in small-scale GTL technology unit. Taking into account specifics of small remote oil fields, GTL technology scheme was chosen among existing types and its material balance wascalculated. The schemes of both associated petroleum gas utilization and power production on site in the small remote fields were suggested and compared to each other from economical and environmental perspectives. Furthermore, the economic effect from themini-GTL technology introduction into the schemes was defined.I avhandlingen uppenbaras problemet med tillhörande petroleumsgaser både i Ryssland och i världen. Analysen av tillhörande oljeutnyttjande metoder för de små avlägsna oljefälten utförs. Avhandlingen visar perspektivet på att skapa låga och medelkraftiga autonoma installationer för energiförsörjning till oljeanläggningarna i de avlägsna områdena med dåligt utvecklad energiinfrastruktur genom att bearbeta tillhörande oljegas i småskaliga GTL-teknologienheten. Med tanke på särdrag hos små avlägsna oljefält valdes GTLteknikprogrammet bland befintliga typer och dess materialbalans beräknades. Systemen för både tillhörande oljeutnyttjande och kraftproduktion på plats i de små avlägsna fälten föreslogs och jämfördes med varandra från ekonomiska och miljömässiga perspektiv. Vidare definierades den ekonomiska effekten från mini-GTLteknikintroduktionen i systemen.
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Bassey, Michael Etim. "Economic viability of a floating gas-to-liquids (GTL) plant / Bassey, Michael Etim." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1577.
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VALE, SILVIO FRANKLIN MONCAO DO. "PRECIFICATION OF MANAGERIAL FLEXIBILITY IN GTL PLANTS USING THE METHODOLOGY OF REAL OPTIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11861@1.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORO objetivo da presente dissertação é capturar o valor da opção de parada temporária que uma planta GTL oferece em cenários econômicos desfavoráveis para mantê-la operando. Desta forma, o autor considera que a metodologia das opções reais é a mais indicada para avaliar tal flexibilidade, sendo assim, o objetivo principal deste estudo é a análise da opção de parar temporariamente através da utilização do processo estocástico (Movimento geométrico Browniano)e a correlação de Cholesky entre cada input e os outputs da planta. O autor acredita que os resultados desta dissertação podem auxiliar os gestores que enxergam flexibilidades em seus projetos a antecipar prejuízos prolongados em cenários desfavoráveis para manter uma planta funcionando.
The objective of this dissertation is to capture the value of the option to temporarily stop that a GTL plant offers in unfavorable economic scenarios to keep it operating. Thus the author believes that the methodology of real options is the best placed to assess such flexibility, and thus the main objective of this study is the analysis of the option to temporarily stop using the stochastic process (geometric Brownian Motion) and the correlation Cholesky between each input and outputs of the plant. The author believes that the results of this dissertion can assist the managers who see flexibilities in its projects to anticipate damages drawn out in favorable scenes to keep a plant functioning.
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SALES, Deivson Cesar Silva. "Desenvolvimento da tecnologia GTL de produção de metanol a partir do gás de síntese." Universidade Federal de Pernambuco, 2013. https://repositorio.ufpe.br/handle/123456789/10386.
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Tendo em vista o desenvolvimento de uma abordagem diferente da convencional adotada para a síntese do metanol, justificado pelo crescimento do mercado de consumo e produção dessa matéria prima, foi desenvolvido um processo de síntese via gás de síntese em reator de mistura. Nesse processo, o leito catalítico foi posicionado em um cesto no interior do reator, que girava em rotações pré-determinadas, entre 200 – 800 RPM, onde foram conduzidas avaliações cinéticas. Operando-se com um catalisador comercial (KATALCOJM 51-8), nas condições definidas por meio de avaliações termodinâmicas, de equilíbrio líquido-vapor e fluidodinâmica, foi determinada a região de operação do sistema, estabelecida em pressões na faixa de 20,0 – 30,0 atm e temperaturas de 473 – 573 K, com base em um planejamento fatorial 3². Foram conduzidas, nessas condições, avaliações dos efeitos de resistência externa, por influência da velocidade de rotação do cesto catalítico, via quantificação do número de Biot. Avaliações do regime de operação nessas condições também indicaram o estabelecimento do regime químico de operação, com domínio da reação catalítica, via determinação do módulo de Thiele modificado. Em operação descontínua com uso do catalisador comercial, produziu-se metanol com conversão média de CO e H2, rendimento e seletividade médios a metanol iguais a 86%, 96%, 39% e 70%, respectivamente a 30,0 atm e 523 K. Foram formulados catalisadores baseados em Cu e Zn sobre γ-alumina, preparados pelo método de impregnação úmida e caracterizados via análises de difração de raios-x, espectrofotometria de absorção atômica e propriedades texturais (área superficial, volume de poros, volume de microporos e raio médio de poros). Em operação descontínua, esses catalisadores tiveram suas atividades catalíticas avaliadas, alcançando conversão de CO, rendimento e seletividade médios a metanol iguais a 32,5%, 25% e 85%, respectivamente. Foram desenvolvidos modelos cinéticos para predição do comportamento dos reagentes e produtos no processo, em termos do modelo de Langmuir-Hinshelwood-Hougen-Watson, a partir dos quais foi possível a quantificação dos parâmetros cinéticos e de equilíbrio. Esses modelos foram estendidos à predição do comportamento das operações em regime contínuo, conduzidas para o catalisador comercial e aqueles formulados.
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Souza, Jos? Roberto de. "S?ntese de Fischer-Tropsch sobre perovskitas LayCu0,4Fe0,6O3." Universidade Federal do Rio Grande do Norte, 2010. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15905.
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Previous issue date: 2010-07-30The current natural gas production of 52 Mm3d-1 and the large projects for its expansion has been setting new boundaries for the Brazilian industry of oil and gas. So far, one of the biggest challenges regards to the logistics for gas transportation from offshore fields. Therefore, the transformation of natural gas into gasoline, diesel and/or olefins via Fischer-Tropsch synthesis would be an alternative to this matter. In this work, the production of hydrocarbons by Fischer-Tropsch synthesis in a slurry reactor was investigated and a perovskite-type catalyst (LayCu0,4Fe0,6O3 ? d) was used with y varying from 0 to 1 on a molar basis. In addition, Nb2O5 support was also applied in order to observe the selectivity of the produced hydrocarbons by the Fischer-Tropsch process. It is shown that the hydrogen conversion was influenced by the support as well as the different phases of the samples. The kinetic results for the CO2 production suffered great influence with the introduction of the Nb2O5 support throughout the series of samples studied. The catalysts allowed obtaining welldefined cuts of hydrocarbons in the range of C1-C6 and C17-C28, and these results were clearly influenced by the support and the lanthanum content. The higher olefin/paraffin ratio obtained was 1.8 when using a non-supported perovskite with y equal to 0.8. This would indicate the suitability of using this material for the production of olefins
A produ??o atual de 52 milh?es m?dia-1 de g?s natural e os grandes projetos para esta expans?o vem estabelecendo novas fronteiras para a ind?stria nacional de petr?leo e g?s, sendo um dos maiores desafios a log?stica para o transporte do g?s oriundo de campos offshore. Uma alternativa seria usar o g?s natural para a produ??o de gasolina, diesel e/ou olefinas atrav?s da s?ntese de Fischer-Tropsch. No desenvolvimento deste trabalho foi investigado a produ??o de hidrocarbonetos via s?ntese de Fischer-Tropsch em um reator slurry mediante uso de catalisadores do tipo perovskita, LayCu0,4Fe0,6O3?d, onde y sofreu varia??o de 0 at? 1 em base molar. A s?ntese dos catalisadores levou em considera??o o estudo da influ?ncia do teor de lant?nio e do suporte (Nb2O5) na atividade e seletividade da rea??o de Fischer-Tropsch, objetivando a produ??o de hidrocarbonetos. As convers?es de H2 foram sensivelmente influ?nciadas pela presen?a de fases existentes em cada amostra, assim como pelo suporte. Os resultados da cin?tica de produ??o de CO2 sofreram grandes influ?ncias com a introdu??o do suporte em toda a s?rie das amostras produzidas. Os catalisadores empregados permitiram a obten??o de cortes bem definidos de hidrocarbonetos na faixa de C1-C6 e C17-C28, sendo estes resultados claramente influenciados pelo suporte e pela varia??o do teor de lant?nio. A maior rela??o olefina/parafina obtida foi de 1,8 para a perovskita com y igual a 0,8 na amostra n?o suportada, viabilizando o uso deste material na produ??o de olefinas
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Francis, Michael Craig. "A techno–economic analysis of an integrated GTL, nuclear facility with utilities production / Francis M.C." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7347.
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The nuclear industry has undergone a revival in recent years, which has been more
commonly termed the nuclear “renaissance”. This renaissance period has brought renewed
interest to the commercial nuclear industry as well as to peripheral or related industries,
particularly in the areas of research and development. Some of the most common research
topics include the integration of nuclear and process technologies, or more specifically the
use of nuclear heat energy in process plants.
Gas–to–liquids (GTL) technology, although often referred to as an unconventional fossil fuel
technology, is a mature technology and successful commercial applications in the state of
Qatar are evidence of that. Likewise, thermal desalination processes such as multi stage flash
(MSF) and multiple effect distillation (MED) are also very mature technologies that have
been in commercial operation for many decades. Both GTL and desalination processes may
be regarded as energy intensive processes that demand large amounts of thermal energy,
which is typically provided by the combustion of fossil fuels. The use of fossil fuels as a
primary energy source, however, has a number of drawbacks: unstable and/or rapidly
increasing prices, negative environmental impact as well as concerns over long term
sustainability. Nuclear energy is far more attractive from a sustainability perspective and also
produces negligible carbon dioxide (CO2) emissions. By utilising nuclear heat energy either
directly or through waste heat in a secondary circuit, process plants become more energy
efficient whilst also emitting less green house gases.
The proposed process design is an integrated nuclear GTL facility: the primary focus is the
integration of heat energy in a typical GTL complex. The secondary focus is the use of
nuclear energy to drive electricity and potable water production. A typical GTL facility
herein refers to the type investigated and proposed in a recent feasibility study conducted by
Sasol Technology and Sasol Chevron Holdings Limited in 2006, which is property of Sasol
Chevron Holdings Limited and Sasol Chevron Holdings Qatar Limited, as part of the Sasol
Chevron Integrated GTL project comprising gas and GTL plants. The proposed integrated
facility is a large industrial complex and Qatar was chosen as a suitable geographic location
for the study for a number of reasons:
* Established GTL industry, which is supported by the government as a means of
monetizing their natural gas resources.
* Extensive natural gas reserves fed from the world’s largest non–associated gas field
* An industrial city, such as Raf Laffan, that contains well established logistical and
engineering infrastructure to support a large industrial complex.
* Socio–economic considerations that warrant the development of additional utilities
generation capacity in Qatar.
* Favourable political climate for the introduction of nuclear energy in the region.
In the proposed design only a handful of units in the typical GTL complex were identified for
heat integration: synthesis gas generation (reforming), hydrogen production unit (reforming)
and the process superheaters. The focus area of the GTL complex was then upstream of the
Low Temperature Fischer Tropsch (LTFT) reaction units and there were no opportunities for
heat integration identified in the downstream product work up (PWU) or refinery units. The
process was modelled as a nuclear steam methane reforming (SMR) process, with nuclear
heat providing the required endothermic reaction energy for the reforming process. The
helium exit temperature from the reforming process was 781.50oC, which meant that the
helium could also be used to superheat the complex high pressure (HP) steam. The
superheated HP steam was then used as feed to the reformers themselves and to drive a back
end Rankine power cycle. A final stage, backpressure turbine then provided low pressure
(LP) steam to drive MSF desalination units. Approximately 40 percent of the total available
nuclear thermal energy was used in the reforming and superheater units. In the helium
Brayton power cycle a significant amount of electricity was generated whilst also providing
low temperature waste heat that was utilized for MED desalination units. The proposed
integrated design thus combined three technologies that together produced large quantities of
their respective products.
The integrated nuclear GTL design also required the introduction of a CO2 shift reactor
downstream of the reforming units to correct the synthesis gas (Syngas) ratio fed to the LTFT
reactors. The CO2 makeup stream was assumed to be imported from offsite. This shift reactor
unit was certainly a departure from the conventional GTL process layout and represented a
significant CO2 credit opportunity, particularly in the context of a large industrial facility
such as that at Ras Laffan. The conventional GTL design also utilizes autothermal reforming
technology that requires oxygen feed to the units, while the nuclear SMR process does not
require oxygen. Thus another benefit associated with nuclear GTL integration would be the
omission of the air seperation units (ASU), which ordinarily require large amounts of energy
to drive the unit air compressors. A pressure swing adsorption (PSA) unit and CO2 wash unit
were also included upstream of the FT reactors, providing both clean Syngas at the required
Syngas ratio as well as a clean, high purity stream of hydrogen to be used in the PWU units.
An economic analysis was performed to gauge the realistic viability of the technical proposal.
In this analysis simple return on investment (ROI) calculations were performed to provide net
present value (NPV) and internal rate of return (IRR) indications. A constant discount rate of
21.25% was used for all economic calculations. The various technologies were also analysed
as stand–alone facilities and then together as an integrated facility. The major drivers or levers
in each of the respective industries were used as bases for low, high and reference economic
analysis. The base case typical GTL complex returned very favourable values with an IRR of
68%. The integrated facility also retuned favourable ROI indictors with an IRR of 42%. In
the context of an integrated nuclear GTL facility, the nuclear portion alone was not
economically viable as most of the energy was used for process heat rather than power
generation. The inclusion of C02 credit revenues only marginally improved the economics of
the nuclear portion of the facility, but obviously contributed positively to the overall facility
ROI indicators. At a CO2 credit value of 90.62 $/ton the nuclear portion of the integrated
facility would become economically justifiable in its own right. However, it may be argued
that such a high CO2 credit value is highly unlikely in the short to medium term future.
The major technical benefits of a nuclear integrated facility include improved carbon
efficiency and measurable CO2 emissions reduction. The typical (base case) GTL facility,
however, has an attractive business case without the integration of the nuclear and
desalination technologies. A decision to invest in such a large, integrated facility would thus
depend heavily on local socio–economic and political factors. The key driver in GTL
economics, and hence the proposed integrated design as well, is the product pricing and
natural gas/crude oil price differential. This is the main reason for presenting low, high and
reference growth cases in the economic analysis. Despite lower NPV and IRR indicators than
the GTL base case, the integrated design still represents an attractive investment. The
comprehensive facility is also an excellent means to monetize gas resources and provide
utilities to a fast growing nation.Thesis (M.Sc. Engineering Sciences (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2012.
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FRANCISCO, MARCELA LOBO. "THE IMPORTANCE OF MANAGERIAL FLEXIBILITY: INVESTIMENT ANALYSIS USING THE REAL OPTION OF THE PLANT GTL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10099@1.
Full textAbstract:
COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORPETRÓLEO BRASILEIRO S. A.
O objetivos desta dissertação é fazer uma análise de investimentos usando a teoria das Opções Reais de uma planta GTL. Está análise é a mais indicada, pois se verificam várias flexibilidades nesta planta em relação aos inputs (pode ser usado mais de um produto como matéria- prima) e em relação aos outputs (existem várias combinações possíveis de produção). Torna-se de grande importância neste caso saber calcular o valor destas opções e verificar se vale a pena ou não a construção de uma planta que possa usar como matéria prima mais de um produto e/ou que possa produzir mais de uma possível combinação de produção. A construção de uma planta que possua a possibilidade de trocar de insumo e/ou trocar a combinação de produção só será viável caso o valor criado pela flexibilidade seja maior do que o custo necessário para implementá-la (investimento adicional e custos operacionais extras). Sendo assim, o objetivo desta dissertação é calcular até quanto a Petrobras estaria disposta a pagar para ter uma planta que possua a opção de swicth use dos inputs e/ou outputs, o valor que ela teria que investir para usufruir desta flexibilidade, e através da diferença entre estes valores verificar se vale a pena ou não a construção da planta com flexibilidade de input e/ou output.
The objective of this dissertation is to do a analysis of investiment using the real option theory for the plant GTL. This analysis is the best because there are many flexibilities in this plant in relation the inputs (the plant can operate with several inputs) and in relation the outputs (there are many possible combination of production). In this case is very important to know how to calculate the value of these options and to verify if it is worthwhile or not the construction of a plant that could use two inputs and/or is able to procuce several possible combinations of production. The construction of the plant that change the input abd /or can changer the production combination is viable if the value created by flexibility is large than the necessary cost to implement its (additional investiment and extra operational costs). So, the objective of this dissertation is to calculate until hen Petrobras would be avaible to pay in order to have a plant that has the option of swicth use of inputs and/or outputs, the value it would have to invest to use this flexibility, and through the difference between these values verify if is worthwhile or not the construction of the plant with the flexibility of input and/or output.
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Souto, Vinícius Suzuki. "Efeito de constrições na dinâmica de vórtices cinemáticos em supercondutores gap-like e gapless." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153801.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Nesse trabalho estudou-se a dinâmica e os fatores de formação de vórtices cinemáticos em supercondutores mesoscópicos sem gap (gapless). Os resultados foram comparados com aqueles de um sistema com gap (gap-like). Para tal, as simulações computacionais foram direcionadas para a solução das equações generalizadas de Ginzburg-Landau dependente do tempo (GTDGL). Primeiramente simulamos amostras homogêneas onde verificou-se que, no sistema gap-like, as correntes se concentram no centro da amostra, com isso, há formação de vórtices cinemáticos. Para criar artificialmente o acúmulo de correntes no centro da amostra, inserimos uma constrição e assim, obtivemos a formação de vórtices cinemáticos em supercondutores gapless. A dinâmica é sempre com um par se formando nas bordas da amostra e se aniquilando no centro. Nota-se que, além da formação de VAv (início do estado resistivo) ocorrer em valores distintos da densidade de corrente aplicada para as diferentes amostras, a corrente crítica apresenta uma pequena diferença entre as amostras gapless e gap-like. Vale ressaltar que parâmetros como o tamanho dos contatos elétricos e a constrição afetam a corrente crítica da amostra, bem como a velocidade média do vórtice cinemático.
In this work we study the dynamics and the formation of kinematic vortices in gapless mesoscopic superconductors. The results were compared to those ones of a gap-like system. Then computational simulations were carried out to solve the Generalized Time-Dependent Ginzburg-Landau equations (GTDGL). Firtly, we simulated homogeneous gap-like and gapless samples where it was found that, in the rst one, the currents concentrate in the center of the sample and then, there was the formation of kinematic vortices. To arti cially promote the crowding of the currents in the center of the sample, we worked with samples a constriction. In this way, kinematic vortices in gapless superconductors were formed. The dynamic is always with a pair forming at the edges of the sample and annihilating in the center. It is noted that, besides the formation of a vortex (antivortex) (begin of resistive state) occurs at distinct values of the applied current density for diferent samples, the electric critical current presents a tiny di erence between gapless and gap-like samples. It is worth mentioning that parameters such as the size of electrical contacts and constriction a ect the critical current of the sample as well as the average velocity of the kinematic vortex.
131002/2016-3
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Sefi, Sandy. "Pay tracing tools for high frequency electromagnetics simulations." Licentiate thesis, KTH, Numerical Analysis and Computer Science, NADA, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1596.
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Over the past 20 years, the development in ComputationalElectromagnetics has produced a vast choice of methods based onthe large number of existing mathematical formulations of theMaxwell equations. None of them dominate over the others,instead they complement each other and the choice of methoddepends on the frequency range of the electromagnetic waves.This work is focused on the most popular method in the highfrequency scenario, namely the Geometrical Theory ofDiffraction (GTD). The main advantage of GTD is the ability topredict the electromagnetic field asymptotically in the limitof vanishing wavelength, when other methods, such as the Methodof Moments, become computationally too expensive.
The low cost of GTD is due to both the fact that there is noruntime penalty in increasing the frequency and that the raytracing, which GTD is based on, is a geometrical technique. Thecomplexity is then no longer dependent on electrical size ofthe problem but instead on geometrical sub problems which aremanageable. For industrial applications the geometricalstructures, with which the rays interact, are modelled bytrimmed Non-Uniform Rational B-Spline (NURBS) surfaces, themost recent standard used to represent complex free-formgeometries.
Due to the introduction of NURBS, the geometrical subproblems tend to be mathematically and numerically cumbersome,but they can be highly simplified by proper Object Orientedprogramming techniques. This allowed us to create a flexiblesoftware package, MIRA: Modular Implementation of Ray Tracingfor Antenna Applications, with an architecture that separatesmathematical algorithms from their implementation details andmodelling. In addition, its design supports hybridisationtechniques in combination with other methods such as Method ofMoment (MoM) and Physical Optics (PO).
In a first hybrid application, a triangle-based PO solveruses the shadowing information calculated with the ray tracerpart of MIRA. The occlusion is performed between triangles andtheir facing NURBS surfaces rather than between their facingtriangles, thus reducing the complexity. Then the shadowinginformation is used in an iterative MoM-PO process in order tocover higher frequencies, where the contribution of theshadowing effects, in the hybrid formulation, is believed to bemore significant.
Thesis presented at the Royal Institute of Technology ofStockholm in 2003, for the degree of Licentiate in ScientificComputing.
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Balchen, Olave Leif Andrés. "Estrategia de rediseño a macroproceso de comercialización e instalación de servicios para la empresa Grupo Gtd." Tesis, Universidad de Chile, 2014. http://repositorio.uchile.cl/handle/2250/116327.
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Tesis para optar al grado de Magíster en Gestión y Dirección de EmpresasGrupo Gtd ha entrado en una fusión de sus áreas comerciales en sus empresas relacionadas, dejando una sola columna vertebral de instalación. La problemática surge cuando un ejecutivo se relaciona a servicios del grupo, y los sistemas hoy no interactúan entre sí. De aquí surge la necesidad de hacer un diseño estratégico de procesos de comercialización e instalación de servicios para la empresa grupo Gtd, de modo tal que mejore el funcionamiento de los sistemas de ingreso de productos y estos cumplan con los requerimientos de los clientes, mediante la innovación y el rediseño de procesos. Para el desarrollo de esta propuesta, se desarrollará un levantamiento de los procesos del macroproceso que refleje las características de la cadena de valor, y luego se pretende desarrollar un modelo que de soporte al rediseño de la cadena de valor. Este modelo basado en la Metodología de Oscar Barros El resultado esperado es por un lado influir en los tiempos de espera del cliente, disminuyendo de 15 a 10 días los tiempos de instalaciones, dejándolo más cercano a los plazos de mercado. Y por otro lado, rediseñar los flujos de comunicación interna en un proceso centralizado, con la cualidad de ir al área competente desde el primer momento, evitando una asignación incorrecta. Dado lo anterior, la eficiencia en la gestión es disminuir los tiempos tanto en las contrataciones como en las espera en los requerimientos de postventa, por lo menos aumentar la satisfacción de clientes en un 30 %. Y al disminuir la probabilidad de que se entregue la información con error se pretende bajar costos de operación en un 20 %. La mejora de los tiempos de instalación debe ser continua, no basta con igualarse al mercado, se deben hacer los esfuerzos para una segunda fase y llegar a tiempos de 8 días. Esto se puede ir logrando a medida que se adquieren los aprendizajes de los procesos y cambian las culturas en las personas, le da una fortaleza diferenciadora para seguir realizando otros cambios internos que le permitirá un crecimiento gradual y controlado para conseguir liderazgo importante en la industria.
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Panahi, Mehdi. "Plantwide Control for Economically Optimal Operation of Chemical Plants : - Applications to GTL plants and CO2 capturing processes." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for kjemisk prosessteknologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-15210.
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In this thesis, the systematic plantwide procedure of Skogestad (2004) is applied to two processes; 1- Post-combustion CO2 capturing processes, 2- Natural gas to liquid hydrocarbons (GTL) plants, in order to design economically efficient control structures, which keep the processes nearoptimum when disturbances occur. Because of the large magnitude of energy consumption in both these processes, optimal operation is of great importance. The self-optimizing concept, which is the heart of the plantwide procedure is used to select the right controlled variables in different operational regions, which when they are kept constant, indirectly give the operation close to optimum. The optimal is to reconfigure the self-optimizing control loops when the process is entered into a new active constraint region, but we try to arrive at a simple/single control structure, which does not need switching, where a reasonable loss in operating economic objective function is accepted. The CO2 capturing process studied here is an amine absorption/stripping system. The chosen objective function for this process is first to minimize the energy requirement while fixed CO2 recovery of 90% is met. This leads to one unconstrained degree of freedom. Maximum gain rule is applied and a temperature close to the top of the stripper is found as the best controlled variable. Further, we introduce penalty on CO2 amount released to the atmosphere, and this results in two unconstrained degrees of freedom. CO2 recovery and a temperature close to the top of the stripper are found as the best individual controlled variables in low feedrate. In higher flue gas flowrates, stripper heat input saturates and the self-optimizing method is repeated to select the right controlled variable for the remaining degree of freedom. We validate the propose control structures using dynamic simulations, where 5 different alternatives including decentralized control loops and multivariable controller are studied. We finally achieve a simple control structure, which handles a wide range of change in throughput and keeps the process close to optimum without the need for switching the control loops or updating the controlled variables setpoints by a costly real time optimizer. The GTL process modeled in this thesis includes an auto-thermal reformer (ATR) for synthesis gas production and a slurry bubble column reactor (SBCR) for the Fischer-Tropsch (FT) reactions. The FT products distribution is determined using a well-known Anderson- Schultz- Flory (ASF) model, where carbon component in CO (consumption rate is found based on the proposed rate by Iglesia et al.) is distributed to a range of hydrocarbons. ASF is a function of chain growth probability and the chain growth is a function of H2/CO ratio. We study different scenarios for chain growth and we arrive at a suitable model for optimal operation studies. The optimal operation is considered in two modes of operation. In mode I, natural gas feedrate is assumed given and in mode II, natural gas feedrate is also a degree of freedom. After optimization, in both modes, there are three unconstrained degrees of freedom. The best individual self-optimizing controlled variables are found and since the worst-case loss value is rather notable, combination of measurements is done, which reduces the loss significantly. Mode II happens when oxygen flowrate capacity reaches the maximum and we show that operation in mode II in this case is in snowballing region where operation should be avoided. Operation at maximum oxygen flowrate capacity is where maximum practical profit can be achieved.
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Truntzler, Marion. "Identification de locus impliqués dans la qualité du maïs enlisage : méta-analyse de GTL et génétique d'association." AgroParisTech, 2011. http://www.theses.fr/2011AGPT0013.
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L’objectif de cette thèse était la mise en place de deux approches complémentaires. En premier lieu, une méta-analyse de QTL a été réalisée à partir des études publiées dans la littérature et d’études deQTL internes à Syngenta, afin de définir de façon plus précise les régions chromosomiques impliquées dans les caractères liés à la digestibilité. La cartographie physique et génétique du maïs ont été utilisés pour identifier et positionner les gènes candidates impliqués dans la qualité de l’ensilage et de tester leurs colocalisations avec les métaQTL. Au total, 37 et 57 métaQTL ont été identifiés pour les caractères de digestibilité et parois respectivement et les gènes candidats colocalisaient significativement avec les intervalles de confiance des métaQTL. Dans un second temps, une étude de génétique d’association a été réalisée dans les régions mise en évidence par la méta-analyse. Le panel utilisé est composé de 314 lignées représentant le germplasm denté et inclut des lignées publiques mais aussi des lignées du matériel élite de Syngenta. Plus de 100 amplicons ont été séquencés et analysés dans les régions d’intérêt puis testés pour leur association avec les caractères de digestibilité. Les associations entre la floraison et les séquences étudiées par Ducrocq et al. (2008) dans la région Vgt1 ont également été étudiés pour évaluer les propriétés de ce panel par rapport aux panels précédemment étudiés dans la littérature et comparer les différents logiciels utilisés en génétique d’association. Nos résultats ont confirmé l’effet de la région Vgt1 sur la précocité de floraison. Neuf associations significatives ont été mises en évidence pour la digestibilité des paroisQuality of silage corn is a trait of major interest for corn breeding in Europe. In order to increase breeding efficiency, it is important to locate precisely the loci (QTL) involved in the variation of this trait and to identify those that carry favorable alleles at these QTL. The goal of this PhD was to carry out two complementary approaches. First, a meta-analysis was performed on the QTL detected in previous studies issued from publications and Syngenta, in order to refine the chromosomal regions involved in traits related to digestibility. Maize physical map and sequence data were used to identify and position candidate genes for silage quality, and to test their colocalization with metaQTL. A total of 37 and 54 metaQTL were found for digestibility and cell wall respectively and the candidate genes colocalized significantly with the metaQTL confidence intervals. Secondly, association mapping was performed on the regions identified through meta-analysis. The panel used for the association tests was composed of 314 inbred lines representing dent European and American germplasm, including public inbred lines and elite material of Syngenta. More than 100 amplicons were analysed in the regions of interest over the whole panel and tested for their association with digestibility traits. Association between flowering time and sequences studied by Ducrocq et al. (2008) at the Vgt1 QTL region were also investigated to evaluate the properties of this panel relative to the ones previously published and to compare different association mapping software. Our results confirm the effect of the Vgt1 region. Nine significant associations were found for digestibility related traits
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Kato, Stephen. "A GTD solution to scattering of plane waves at oblique incidence by a dielectric coated circular cylinder." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345562403.
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Liang, Ming-Cheng. "A generalized uniform GTD ray solution for the diffraction by a perfectly-conducting wedge with convex faces /." The Ohio State University, 1988. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487594970650836.
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Ekbom-Claesson, Åsa, and Kristina Kronestrand. "När graviditeten blir patologisk : kvinnors upplevelse och faktorer som påverkar livskvalitén när graviditeten blir en gestational trofoblastsjukdom (GTD)." Thesis, Sophiahemmet Högskola, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:shh:diva-3065.
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SAMMANFATTNING Gestational trofoblastsjukdom (GTD) är en ovanlig sjukdom som drabbar kvinnor under eller efter en graviditet. Cirka 145 kvinnor drabbas årligen i Sverige av sjukdomen och av dem får cirka 12 kvinnor den maligna sorten som måste behandlas med cytostatika. Sjukdomen påverkar livssituationen för de drabbade paren på många olika plan, både fysiskt och psykiskt. Då sjukdomen är mycket ovanlig är det viktigt att dessa kvinnor får stöd och behandling av sjukvårdspersonal med goda kunskaper för att hjälpa kvinnorna till god livskvalité. Syftet var att undersöka kvinnors upplevelse efter att ha drabbats av gestational trofoblast-sjukdom och faktorer som påverkar deras livskvalitet. Som metod valdes litteraturöversikt och 14 artiklar inkluderades i arbetet. Databaserna som användes var PubMed, CINAHL och PsycINFO. De utvalda artiklarna har granskats, diskuterats och därefter sammanfattats för att kunna urskilja likheter och olikheter. I resultatet framkom fem kategorier; Psykisk hälsa, Fysisk påverkan, Relationer och sexualitet, Graviditet och barn samt Information och stöd. Livskvaliteten påverkades bland annat av oro och ångest, rädsla för att inte kunna få genomgå en normal gravditet och hade inverkan på relationer och sexuallivet. Slutsatsen visar att sjukdomen påverkar livskvaliteten, inom flera områden och i varierande grad, för de drabbade kvinnorna och deras familjer. Livskvalitén kan påverkas av oro och ångest, rädsla för att inte kunna få genomgå en normal graviditet och har en inverkan på relationer och sexuallivet. Behovet av relevant, tydlig och sakkunnig information är stort för att få en delaktig och trygg patient. En specialiserad vård som besitter adekvat kunskap är viktigt, för att kunna understödja och främja en god livskvalitet hos den som drabbats. Nyckelord: Trofoblastsjukdom, oro, livskvalitet, ångest, stöd.
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Wiart, Joe. "Propagation des ondes radioelectriques en milieu urbain dans un contexte microcellulaire. Analyse par la gtd et validation experimentale." Paris 6, 1995. http://www.theses.fr/1995PA066488.
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La propagation des ondes radio electriques est etudiee en milieu urbain quand l'antenne d'emission est sous le niveau des toits. Les caracteristiques principales du signal radio et les methodes de calcul du champ electromagnetique sont etudies. Les mecanismes qui gouvernent la propagation des ondes dans ce contexte sont analyses a l'aide de la theorie des rayons et de la theorie uniforme de la diffraction. Les resultats qui decoulent de cette etude sont utilises dans la mise en uvre d'un outil de prediction de l'affaiblissement et de couverture radio. L'ensemble des resultats est valide experimentalement par comparaison a des mesures
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Rojas-Teran, Roberto G. "A uniform GTD analysis of the EM diffraction by a thin dielectic/ferrite half-plane and related configurations /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487259580264106.
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Boström, Lukas. "Understanding Educational Causes of Terrorism : An empirical analysis investigating the global relationship between specific educational attributes and its effects on domestic terrorism activity." Thesis, Uppsala universitet, Institutionen för freds- och konfliktforskning, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-373040.
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The purpose of this study is to develop further knowledge of how specific educational attributes such as educational quality is affecting domestic terrorism activity. Using a time frame between 1999 and 2007, involving 133 countries. The research results indicate that educational quality does in most instances have a negative correlating effect on domestic terrorism activity. Though not to the same extent as the hypothesis suggests, where school completions rates appears to positively correlate with increased risk of domestic terrorism activity. However as theorized quality education proves to have more significant importance for a reduced risk of domestic terrorism compared to previous educational indicators that generally positively correlate with increased risk of domestic terrorism, when controlling for specific country conditions.
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Kander, Keethan. "Utilizing nuclear process heat to reduce the CO2 generated by an SMR process in a GTL environment / K. Kander." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4859.
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Gas to liquids (GTL) technology, although an attractive method for meeting
liquid fuel requirements into the future, has an inherent concern regarding the
environmental impact of dealing with the large amount of carbon dioxide that
is generated. In this investigation, the potential to reduce this carbon dioxide
footprint by utilising process heat from high temperature helium at 950oC
downstream of a High Temperature Gas (cooled) Reactor (HTGR) is
examined.
The study compares a base case steam methane reformer (SMR) heated by
the combustion of natural gas to a nuclear heated steam methane reformer
heated by hot helium from one HTGR. It has been shown that it is possible to
reduce the carbon dioxide footprint almost entirely for the synthesis block of a
GTL facility. Process heat integration from one HTGR has the potential to
reduce the carbon dioxide footprint of an SMR by approximately 42 tons per
hour.
The full potential of one HTGR in terms of carbon dioxide reduction for a GTL
facility was also investigated. This was achieved by estimating the cogeneration
potential impact on carbon dioxide emissions where the residual
heat in the helium stream downstream of the reformer was used for power
generation. The overall amount of carbon dioxide reduction from both the
reformer and power generation facility was then quantified and an economic
study was completed. The study shows that with one HTGR it would be
possible to reduce the carbon dioxide emissions of a GTL facility by almost
200 t/h if nuclear process heat was used in the reformer and nuclear power
generation was used instead of conventional coal based power generation.
Results from the economic study show that industry would have to incur an
operating cost increase of approximately R200, at current natural gas prices,
to reduce their carbon dioxide emissions by one ton if nuclear energy was
used as a process heat source and for power generation.Thesis (M.Sc. Engineering Sciences (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2010.
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Wiart, Joe. "Propagation des ondes radio-électriques en milieu urbain dans un contexte microcellulaire : analyse par la GTD et validation expérimentale /." Paris : École nationale supérieure des télécommunications, 1996. http://catalogue.bnf.fr/ark:/12148/cb35827751c.
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Th. doct.--Électron. et communications--Paris--ENST, 1995.Thèse délivrée en association avec l'Université de Paris 6. Annexes en français et en anglais. Notes bibliogr. Résumés en français et en anglais.
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Quiroga, Gelsio Pereira. "Uso de gás natural para produção de óleo diesel no Brasil a partir da rota gás-to-liquids: estudo de viabilidade técnico-econômica usando reservas do Pré-sal." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/106/106131/tde-11112016-090137/.
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Devido à sua natureza, o gás natural (GN) tem na distância aos pontos de consumo um obstáculo para sua utilização, a qual vai além simples queima para geração de energia ou obtenção de calor. Portanto, é importante que sejam discutidos novos métodos para distribuí-lo e transformá-lo em fontes de energia de maior valor agregado ou em matéria-prima para fabricação de produtos a serem utilizados na indústria química. Uma opção é a conversão do GN em combustíveis líquidos de pronto uso como óleo diesel, gasolina e querosene de aviação através da rota Gas-To-Liquids (GTL). O presente trabalho avalia o potencial da tecnologia GTL no contexto do crescimento da oferta de gás natural no Brasil pelos gasodutos Rota 2 e Rota 3, contextualizando o cenário brasileiro desse energético, as perspectivas futuras e o estado da tecnologia GTL com o processo Fisher-Tropsch. Para tanto, é simulado e analisado o desempenho econômico de uma planta de diesel GTL operante por 30 anos em cenários de preços de insumo e produto obtidos por projeções de reconhecimento internacional.The usage of natural gás (NG) is related to the distance to the final customers, that is a real obstacle to its full utilization which is beyond the usage as fuel for electricity or heat generation. It is important to prospect, analyze and propose new methods for distribution and transformation of this important energy suppy to more value added products or special raw material for the chemical industry. The transformation in ready for use liquid fuels like diesel, gasoline and kerosene through the gas-to-liquid route (GTL) is one of the options. This dissertation evaluates the GTL technology in a context of the NG additional volume available through 2 new pipelines coming from offshore, Rota 2 and Rota 3 in the Brazilian context of NG current usage and its future perspectives taking advantage of this additional availability via the traditional and long term tested GTL Fischer-Tropsch (FT) technology. A GTL FT Diesel plant operating for 30 years was taken as an example considering different scenarios for NG and Oil prices retrieved from the IEA data base that is internationally considered as a consistent source of information.
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IMBELLONI, Rosa Maria. "Paradigmas do desenvolvimento no Nordeste : Do GTDN ( Grupo de Trabalho para o Desenvolvimento Econômico do Nordeste) ao GTI (Grupo de Trabalho Interministerial para recriação da SUDENE)." Universidade Federal de Pernambuco, 2008. https://repositorio.ufpe.br/handle/123456789/9515.
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Previous issue date: 2008Conselho Nacional de Desenvolvimento Científico e Tecnológico
Neste trabalho construímos reflexão sobre as transformações ocorridas no Nordeste, com enfoque na questão das desigualdades regionais. Para tanto, analisamos as propostas de políticas de desenvolvimento direcionadas à SUDENE (Superintendência do Desenvolvimento do Nordeste). Um marco para análise refere-se à primeira proposta de criação da SUDENE, elaborada pelo Grupo de Trabalho para o Desenvolvimento do Nordeste (GTDN) no final da década de 50 e, portanto, refere-se ao modelo desenvolvimentista, com a proposta Uma Política de Desenvolvimento Econômico para o Nordeste . Outro marco de análise refere-se à proposta de recriação da SUDENE, elaborada pelo GTI (Grupo de Trabalho Interministerial para Recriação da SUDENE), em 2003 e apresenta um novo modelo de desenvolvimento para o Nordeste com a proposta Bases para a Recriação da SUDENE Por uma Política de Desenvolvimento Sustentável para o Nordeste . A pesquisa é qualitativa com análise de conteúdo e tem como referência os documentos que apresentam as duas propostas de política de desenvolvimento para o Nordeste no processo de criação e recriação da SUDENE. O propósito é refletir os dois modelos de desenvolvimento implantados na região assim como, confrontar as duas propostas de política de desenvolvimento. Entre possibilidades e limites, entendemos que o modelo de desenvolvimento elaborado pelo GTI para o Nordeste representa um novo marco de transformações intervencionistas na região
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Lira, Rodrigo Lucas Tenorio Calazans de. "Análise e Otimização da Produção de Hidrocarbonetos Líquidos Via a Reação de Fischer Tropsch Por Meio da Tecnologia Gas To Liquid (GTL)." Universidade Federal de Pernambuco, 2012. https://repositorio.ufpe.br/handle/123456789/11916.
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A tecnologia de produção de combustíveis sintéticos iniciou seu desenvolvimento a partir de 1919, na Alemanha, tendo o carvão mineral como insumo para a gaseificação. Com o passar dos anos novos insumos foram utilizados, como a biomassa e o gás natural, cada um com rotas tecnológicas próprias. Com o uso do gás natural esta rota tecnológica é conhecida como Gas-To- Liquids (GTL) sendo uma transformação química que gera faixas de hidrocarbonetos líquidos e estáveis à temperatura e pressão ambientes. Este processo tem como etapa principal etapa à reação de Fischer Tropsch (FT), pois transforma gás síntese resultante da reforma do gás natural em hidrocarbonetos líquidos que ao serem refinados tornamse importantes produtos para indústria petroquímica, de transporte e áreas afins. Essa transformação pode ser realizada no próprio local de produção do gás, evitando investimentos e problemas ambientais na construção de gasodutos. No Brasil, o gás natural apresenta crescente incremento da sua produção, e forte aumento das suas reservas, como por exemplo, a descoberta do pré-sal e o gás natural presente pode estar tanto associado quanto não-associado ao petróleo. Devido às estruturas de plataformas normalmente se localizarem em áreas remotas, torna-se custoso o aproveitamento desse gás que é liberado pela produção do óleo, sendo o mesmo queimado ou ventado. Devido às restrições estabelecidas pela legislação ambiental, a queima do gás natural nas plataformas de produção passa a ser problemática e crítica. Este trabalho teve como objetivo desenvolver e avaliar por meio de simulação computacional uma planta de GTL na produção de hidrocarbonetos líquidos via a reação de FT e utilizá-lo na otimização do processo, na busca por um processo com maior capacidade produtiva e com menores gastos energéticos, gerando um melhor aproveitamento do gás natural, produzindo materiais com maior valor agregado. Foram utilizados os softwares de simulação MATLAB® e HYSYS®, que permitiram a analise de resultados satisfatórios para a conversão e distribuição de hidrocarbonetos gerados em comparação com o descrito pela literatura. A qualidade dos hidrocarbonetos gerados foi analisada pela avaliação do diesel obtido.
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Van, Niekerk Bertina Freda. "Functional and structural diversity of the microbial communities associated with the use of Fischer–Tropsch GTL Primary Column Bottoms as process cooling water / van Niekerk B.F." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7284.
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Despite emerging water shortages, most water is only used once, and often with low efficiency. However, with appropriate treatment, water can be re–used to reduce the demand on freshwater sources. The Department of Water Affairs, South Africa, promotes industries to reduce discharges into water resources in order to sustain an overall good water quality of all water systems. All of this ultimately leads to industries striving towards zero effluent discharge. Primary Column Bottoms (PCBs) is a wastewater stream derived from the Fischer–Tropsch Gas to Liquid process and consists mainly of organic acids, but no nitrogen or phosphorous, which by implication excludes possible biodegradation. In the operation of cooling towers in industrial processes, cooling water quality has a direct impact on the cooling performance of the system, where nutrient levels may affect fouling, scaling and corrosion observed in the cooling towers. Fouling, scaling and corrosion affect the operating efficiency of cooling water systems and may necessitate the addition of chemical agents to control these phenomena. This has a financial and labour time impact on the operation of these systems.
In this study a mini cooling tower test rig was operated with a synthetic PCB effluent as cooling water and various cycles of concentration, pH and linear flow velocities (LFVs). A constant delta temperature of 10 °C was maintained. Cycles of concentration (COC) evaluated included 2, 4 and 6 cycles of concentration and linear flow velocities evaluated was 0.6 m/s, 0.9 m/s and 1.2 m/s. Fouling, scaling and corrosion rates were determined using corrosion coupons and heat exchanger tubes for mild steel and stainless steel. Besides the evaluation of the various operational parameters for fouling, scaling and corrosion, the possibility for chemical oxygen demand (COD) removal by operating the cooling tower as a bioreactor was also evaluated. To this end nutrient correction was applied to the reactor to allow for a CNP ratio of 100:10:1.
With regard to fouling, scaling and corrosion, mild steel was more affected by fouling, scaling and corrosion compared to stainless steel where almost no fouling, scaling and corrosion was observed. Overall increased linear flow velocities resulted in higher fouling and scaling rates, whereas lower linear flow velocities resulted in decreased corrosion rates. In terms of cycles of concentration, increased COC resulted in higher fouling, scaling and corrosion rates. Despite the high nutrient removal levels, the accompanying fouling, scaling and corrosion was still below the particular industry’s guidelines.
Besides physical–chemical evaluation of the towers under the various operational conditions, culture–dependent and culture–independent methods were also employed. Concerning culture–dependent approaches the study demonstrated that aerobic and anaerobic organisms are present in both the planktonic and sessile phase of the cooling tower reactors. Heterotrophic aerobes were found to be the most abundant under all the operating conditions. Sulphate reducing bacteria were more abundant in the sessile phase of the cooling towers, and the presence of high sulphate levels in the experiments could be indicative of the sulphate reducing bacteria actively participating in the microbial community. Lower than expected corrosion levels, however, suggest that a combination of the organisms in the biofilm rather than sulphate reducing bacteria alone, contributed to the corrosion rates observed. Culture–independent methods, specifically phospholipid fatty acid analysis supported the results from the culture–dependent methods. Furthermore results demonstrated that linear flow velocity had a greater effect on the community structure than cycles of concentration. Finally molecular methods, specifically denaturing gradient gel electrophoresis, found that increasing cycles of concentration resulted in increased microbial community diversity, while increasing linear flow velocity resulted in decreased microbial community diversity.
Regarding COD removal, nutrient correction of the synthetic PCB effluent achieved 89.35 % COD removal at 2 COC and 1.2 m/s LFV, while 80.85 % COD removal was achieved at 4 COC at 1.2 m/s LFV. From these results it was recommended that the operation of the cooling tower should be at 4 COC and 1.2 m/s, which despite slightly lower % COD removal, were characterised by fouling, scaling and corrosion rates well within guidelines.Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2012.
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Callari, Roberto. ""Produção de óleo diesel limpo a partir do gás natural: estudo de viabilidade técnico-econômica para a instalação de uma planta GTL (gas-to-liquids) no Brasil"." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-24042007-185230/.
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CALLARI. R. Produção de óleo diesel limpo a partir do gás natural: estudo de viabilidade técnico-econômica para a instalação de uma planta gtl (gas-to-liquids) no Brasil. 2007. 84 p. Tese de Mestrado ? Programa Interunidades de Pós-Graduação em Energia. Universidade de São Paulo. A tecnologia de produção de combustíveis sintéticos iniciou seu desenvolvimento a partir de 1919, na Alemanha, tendo o carvão mineral como insumo para a gaseificação. Este processo conhecido como Gas-To-Liquids (GTL) é uma transformação química que gera produtos líquidos e estáveis à temperatura e pressão ambientes. Essa transformação pode ser realizada no próprio local de produção do gás, evitando investimentos e problemas ambientais na construção de gasodutos. No Brasil, o gás natural apresenta crescente incremento da sua produção, e forte aumento das suas reservas, tanto associado quanto não-associado ao petróleo. Dessa forma, como as estruturas de plataformas normalmente se localizam em áreas remotas, torna-se custoso o aproveitamento desse gás que é liberado pela produção do óleo, sendo o mesmo queimado ou ventado. Devido às restrições estabelecidas pela legislação ambiental, a queima do gás natural nas plataformas de produção passa a ser problemática e crítica. Este trabalho visa avaliar a economicidade da implantação de uma planta para a produção de GTL no Brasil, de modo a permitir a manutenção da produção de petróleo dentro das limitações das leis ambientais, e também gerar um melhor aproveitamento do gás natural, produzindo materiais com maior valor agregado. Assim, para desonerar a produção dos líquidos, a instalação de plantas de transformação de gás natural em GTL, centralizada em áreas de grande produção de gás associado, poderia ser a solução para a queima do gás liberado na produção do óleo. Da mesma forma, as plantas de transformação em GTL poderiam permitir a monetização do gás remoto, através da facilidade de transporte do GTL produzido. Palavras-Chave: gás natural, gas-to-liquids, avaliação econômica, diesel limpo, Fischer-TropschCALLARI. R. Production of liquid hydrocarbons employing Natural Gas: a study of the technical and economical feasibility of a GTL plant in Brazil, 2007. 84 f. Work. Program of Post-Graduation in Energy, Universidade de São Paulo, São Paulo, 2007. The development of the technology for the production of synthetic fuels from the gasification of coal started in 1919 in Germany. For a period of time the liquid hydrocarbons production increased and within the years, it was almost discontinued. The technology known as Gas-To-Liquids (GTL) refers to a chemical transformation that generates liquid products that are stable at room temperature and pressure. The transformation can be accomplished close to the natural gas production sites. In Brazil, the production and use natural gas has been growing because of the increase of the reserves of both, associated and non-associated gas. Natural gas is produced from oil explotation. The production of the liquid fractions requires processing steps. Since the offshore installations are located in distant areas, the use of the gas produced is expensive and in many cases, the gas is burned or exhausted. Due to environmental restraints the gas burning turns to be a critical issue. In order to cheapen the production of liquid products, the installation of plants to transform natural gas through the GTL technology, in associated oil and gas production installations could be the solution for the gas burning or exhaustion. The GTL plants could allow the monetization of the remote gas through the transportation of the GTL fuels produced. This work presents an evaluation of the economic costs for the implantation of a GTL plant in Brazil, in a way that allows the oil production to be kept within the environmental requirements and to generate a better use of natural gas.
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Rigolin, Pascoal Henrique da Costa. "Avaliação global dos modos energéticos de transporte do gás natural inclusive como energia secundária." Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-05092007-161143/.
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O objetivo do trabalho é fazer a avaliação global de alguns dos modos energéticos de transporte do gás natural (gasodutos, GNL e GNC), inclusive como energia secundária (eletricidade e GTL). Para a escolha do melhor modo de transporte, além dos custos de cada projeto, serão considerados outros três fatores, que são: impactos ambientais, impactos sociais e riscos políticos. Para isto foi escolhida uma ferramenta de análise conhecida como Avaliação de Custos Completos (ACC), sendo que esta considera os quatro fatores citados anteriormente como de mesma importância na avaliação para um planejamento que vise a sustentabilidade. Para melhor visualização e entendimento do trabalho, foi feito um estudo de caso para o transporte de energia (gás natural e/ou eletricidade) para atender mercados consumidores na região de fronteira entre o Brasil e a Bolívia. Fundamentalmente o estudo do transporte foi feito em solo boliviano, correspondente entre os campos produtores de gás, localizados em Margarita, até a região de fronteira próxima a Corumbá no Mato Grosso do Sul (MS), e também próxima a uma região com grandes jazidas de minério de ferro conhecida como El Mutún. Metodologicamente dentro das quatro dimensões consideradas, foram usados alguns subcritérios mais relevantes para esta análise. Para todos os sub-critérios foram atribuídas notas específicas, de acordo com a região e com o tipo de transporte de energia, e após isto os dados foram passados para um software de tomada de decisão chamado Decision Lens, obtendo assim um rank das melhores opções transporte para a região. Como resultado, o mais coerente para atender a região, são gasodutos de transporte para as demandas elétricas e de gás natural (consumo do MS mais Mutún) e trens carregados com derivados líquidos do gás natural (GTL) para atender a demanda de diesel do MS.The objective of this work is to make a global evaluation of some energy ways of transport of natural gas (gas-pipelines, LNG and CNG), as well as secondary energy (electricity and GTL). For the selection of a better way of transport, beyond the costs of each project, others three factors were considered: environmental impacts, social impacts and political risks. To perform this, a tool of analysis known as Evaluation of Complete Costs (ACC in portuguese) was chosen. This tool considers the four factors above mentioned as having the same importance in the evaluation process for planning that aims towards sustainability. For better visualization and understanding of the work, a case study for energy transport was made (natural gas and/or electricity) to supply the consumer markets in the region bordering Brazil and Bolivia. Basically the study of the transport was made in Bolivian territory; at the producing gas fields located in Margarita as far as the region bordering Corumbá in the Mato Grosso do Sul area, and also next to a region with great known iron ore deposits known as El Mutún. Methodologically, within the four dimensions above, some more relevant sub-criteria for the analysis were used. For all the sub-criteria considered specific ranks were taken, in accordance with the region and type of transported energy, and after this the data was fed to a software called Decision Lens, thus getting a rank of the best options to carry gas to the region. The results, most coherent way to supply gas to the region, happens to be gas-pipelines of transport for the electric and natural gas demands (consumption in MS plus Mutún) and trains with liquid derivatives of natural gas (GTL) to supply care of the demand of diesel of MS.
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Langenbrunner, Nisrene A. "Understanding the Responses of a Metal and a CMCTurbine Blade during a Controlled Rub Event using a Segmented Shroud." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366191740.
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Nakashima, Marcelo Reis. "O PETAR: geografia, contradições e desenvolvimento." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-06062018-102334/.
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Esta pesquisa abordou a questão do desenvolvimento social e econômico do Parque Estadual Turístico do Alto Ribeira (PETAR), localizado no sul do estado de São Paulo, a partir de um estudo geográfico realizado sob a luz da tríade analítica GTP: Geossistema, Território e Paisagem. Partindo dessa análise geográfica, foi possível identificar como as potencialidades e fragilidades do meio físico influenciaram na territorialização da região onde hoje se encontra o parque, e como a paisagem cultural é construída sobre esta realidade. Com isso foi possível contrapor a interpretação dos dados levantados ao Plano de Manejo proposto para o PETAR em 2010, que se encontra, desde aquele ano, sob análise no Conselho Estadual do Meio Ambiente do estado de São Paulo. O documento apresenta contradições internas no que tange à exploração dos recursos minerais. Com a aprovação da Lei Estadual 16.260/2016, que concede 25 unidades de conservação para a exploração da iniciativa privada, é necessário que não restem pontos obscuros no Plano de Manejo, para que fique claro quais são os recursos que poderão ou não serem explorados. Há indícios de que neste processo os interesses econômicos se sobrepuseram tanto ao objetivo de preservação da área como ao do desenvolvimento socioeconômico. Com essa problemática em foco, discutimos como a Geografia e as ciências, de maneira geral, podem ser úteis ao processo civilizatório ao estabelecer critérios éticos de forma objetiva, apontando assim, as causas dos problemas regionais relacionados à territorialização, as contradições políticas deste processo e de que forma seria possível promover o desenvolvimento socioambiental na região. Um dos principais problemas que levantamos foi a questão das restrições às atividades econômicas impostas pela legislação ambiental. Tendo o turismo como única fonte de sustento possível, a região se tornou altamente dependente dos programas de transferência de renda que, nos últimos anos, provaram ser cruciais para a redução da pobreza extrema e evolução dos índices de desenvolvimento humano. Uma vez que uma flexibilização muito grande das restrições ambientais seria desaconselhável e, levando em consideração que a área do parque é ocupada, historicamente, por populações tradicionais, como comunidades quilombolas, concluímos que seria razoável demandar do estado alguma compensação financeira. Esta medida evitaria que recaíssem, exclusivamente sobre a população local, os custos de uma conservação ambiental que é de interesse do conjunto da sociedade.This research addressed the issue of the social and economic development of the Upper Ribeira State Tourist Park (PETAR), in the state of São Paulo, Brazil, from a geographic study conducted under the light of the analytical triad GTL: Geosystem, Territory and Landscape. Based on this geographical analysis, it was possible to identify how the potentialities and fragilities of the physical environment influenced the territorialization of the region where the park is today, and how the cultural landscape is built on this reality. Thus, it was possible to counter the interpretation of the data collected with the proposed Management Plan for PETAR in 2010, which has been under analysis by the State Environmental Council of the state of São Paulo since that year. The document presents internal contradictions regarding the exploitation of mineral resources. With the approval of State Law 16.260 / 2016, which grants 25 conservation units for the exploitation of the private initiative, it is necessary that there are no obscure points in the Management Plan so it is clear which resources may or may not be exploited. There are indications that, in this process, economic interests overshadowed both the objective of preserving the area and that of socioeconomic development. With this problematic in focus, we discuss how Geography and the sciences, in general, can be useful to the civilizational process by establishing objective ethical criteria, thus pointing to the causes of regional problems related to territorialization, the political contradictions of this process and how it would be possible to promote socio-environmental development in the region. One of the main problems raised is the issue of the restrictions on economic activities imposed by the environmental legislation. With tourism as the only possible source of income, the region has become highly dependent on income transfer programs which, in recent years, have proved to be crucial for the reduction of extreme poverty and the improvement of the human development indexes in the area. Since a significant relaxation of environmental restrictions would be inadvisable, and considering that the area of the park has historically been occupied by traditional populations such as quilombola communities, we have concluded that it would be reasonable to demand financial compensation from the state. This would prevent the local population from paying, alone, for the costs of an environmental conservation, that is in the best interest of society, as a whole.
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Slabbert, Savia Susanna. "Evaluation of the suitabil[i]ty of Fischer-Tropsch gas-to-liquid (GTL) Primary Column Bottoms as process cooling water : analysis of microbial community dynamics, fouling, scaling and corrosion / Savia Susanna Slabbert." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1309.
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Water in South Africa is becoming limiting due to economic growth, social
development and the country's water demand that exceed its water availability. Water
conservation in the industry can be accomplished by the reuse of process water instead
of direct treatment and discharge. By reusing a process effluent as cooling water in
cooling towers, the water requirements of an industry, such as Sasol, will be lower and a
zero effluent discharge scenario could be achieved.
At Sasol, during the gas-to-liquid (GTL) conversion process, natural gas is converted to
diesel and other products. During this process an aqueous effluent stream is produced
in the Fischer-Tropsch (F-T) reactors known as Primary Column Bottoms. Primary
Column Bottoms can be re-used as cooling water within cooling towers. Although this
approach is technically feasible, the re-use of process water in cooling systems is
characterised by major problems (fouling, scaling and corrosion) due to the complicated
chemistry of the process water and the increased nutrient loads within the system.
The aim of this study was to evaluate the suitability of Fischer-Tropsch gas-to-liquid
Primary Column Bottoms as process cooling water by analysing the microbial
community dynamics, fouling, scaling and corrosion. Due to the corrosive nature of
this process effluent, stabilisation of the water was essential. To determine whether
efficient stabilisation was attained, an accelerated corrosion test was performed.
Influence of the external operating parameters within the cooling tower on the rate of
fouling, scaling and corrosion were also determined. Structural and functional diversity
of planktonic and sessile communities were studied by making use of conventional
microbiological techniques (plate counts, MPN technique) and molecular methods
(PLFA, DGGE).
The accelerated corrosion test of 28 days conducted on mild steel and stainless steel
(316L) corrosion coupons accelerated corrosion by immediately establishing the mature
natural environment that causes corrosion. The test solution was stabilised as well as
non-stabilised synthetic Primary Column Bottoms, in order to compare the effect of
stabilisation. Scaling and corrosion indices were also calculated on stabilised and non-stabilised
water to determine the scaling and corrosive tendencies of the water and how this correlates with the actual corrosion results obtained. According to the Langelier
Saturation Index (LSI), Rymar Stability Index (RSI) and the Puckorius Scaling Index
(PSI) the stabilised water was slightly scale forming with little corrosion and the non-stabilised
water being more corrosive than scale forming. Average corrosion rate of the
stabilised water was 0.032 m d y and 0.049 m d y for non-stabilised water. Average
scaling rate was calculated as 7.269 mg/dm2/d for stabilised water and 5.853 mg/dm2/d
for non-stabilised water. It can therefore be concluded that effective stabilisation was
achieved since stabilised water was less corrosive than non-stabilised water which was
also confirmed through experimental data (corrosion rates from accelerated corrosion
test) and corresponded with the corrosive tendencies obtained from the scaling and
corrosion indices.
A lab-scale cooling tower was operated with stabilised synthetic Primary Column
Bottoms as cooling water. Five experiments were conducted under varying flow rates
and cycles of concentration. Influence of the external operating parameters (linear flow
velocity and cycles of concentration) on fouling, scaling and corrosion rates of mild
steel and stainless steel (316L) corrosion coupons and heat exchanger tubes were
determined through weight loss measurements. Routine physico-chemical analyses,
EDS (energy dispersive spectrometry) microanalysis as well as scaling and corrosion
indices of each experiment were also compared, in order to evaluate the influence of
cycles of concentration and linear flow velocity. Based on the results obtained, it was
evident that the variation in cycles of concentration and linear flow velocity had a
significant effect (p0.05) on the fouling, scaling and corrosion rates on the mild steel
corrosion coupons and heat exchanger tubes. Experimental runs operated at low flow
rates of 0.6mIs and 0.9 d s resulted in relative high fouling, scaling and corrosion rates.
Operation at 3 and 4 cycles of concentration had the highest scaling and corrosion rates.
The COD within the cooling tower was not removed by the microorganisms within the
planktonic and sessile communities and resulted in a build-up of COD in the sump.
Thus, the cooling tower cannot be used as a bioreactor to biologically degrade volatile
organic acids and hydrocarbons.
To evaluate the structural and functional diversity of the bacterial and fungal
communities. plate counts, most probable number technique, phospholipid fatty acid
(PLFA) analysis as well as denaturing gradient gel electrophoresis (DGGE) was used. According to PLFA profiles the community structure within the planktonic and biofilm
samples of the experiments operated at low linear flow velocities were similar. The
same percentages of Gram-positive, Gram-negative bacteria and fungi occurred,
The community structure composition of the planktonic and sessile phases in the
experiments operated at higher linear flow velocities was also similar. PLFA analysis
concluded that the highest estimated viable biomass was in experiment 1 which had a
low linear flow velocity of 0.6 d s . Shannon-Weaver index analysis of DGGE profiles
(general structural diversity) indicated that the planktonic bacterial diversity of
experiment I and 2 were the highest. Experiment I and 2 were operated at a linear flow
velocity of 0.6 and 0.9 m/s respectively. The biofilm samples that had the highest
Shannon-Weaver diversity index were experiment 1 and 5. Both experiment 1 and 5
were operated at a linear flow velocity of 0.6 m/s. Morphological changes between
planktonic and sessile communities were monitored through scanning electron
microscopy (SEM). SEM results illustrated that the planktonic and sessile microbial
populations throughout the five experiments were similar, based on morphology.
According to the results obtained from the MPN technique, the experiment operated at
the lowest linear flow velocity had the highest numbers of sulphate reducing bacteria
and also resulted in the highest corrosion rate. Both experiments that were operated at a
low linear flow velocity of 0.6 d s had the highest bacterial numbers and also resulted
in high fouling rates. However, no relationship exists between the percentage increase
in the numbers of aerobic bacteria and the cycles of concentration at which the cooling
tower was operated. These observations are supported by results from PLFA profiles
that showed that the community structure within the planktonic and sessile samples of
the experiments operated at low linear flow velocities were similar. The planktonic and
sessile phases of these two experiments had similar levels of Gram-positive-, Gram-negative-
bacteria and fungi. The community structure composition of the planktonic
and sessile phases in the experiments operated at high linear flow velocities was also
similar. PLFA analysis further demonstrated that the highest estimated viable biomass
was in the experiment operated at a low linear flow velocity of 0.6 m/s. Shannon-
Weaver index analysis of DGGE profiles (general structural diversity) also indicated
that the planktonic bacterial diversity during operation at low linear flow velocities were
the highest. Although scanning electron microscopy results illustrated that the
planktonic and sessile microbial populations throughout the five experiments were generally similar. these results supported the observations of the other techniques.
These techniques all supported the notion that corrosion rates may not be directly
related to the total microbial biomass or the number of species on mild steel or stainless
steel. Corrosion rates seem to be more profoundly affected by biofilm composition
within the sessile phase.
Based on the results obtained when using Primary Column Bottoms as cooling water, it
were evident that variation in cycles of concentration and linear flow velocity had a
significant effect (p>0.05) on the fouling, scaling and corrosion rates on mild steel
corrosion coupons and heat exchanger tubes. Low linear flow velocities resulted in
high fouling rates, increased bacterial numbers as well as high bacterial and fungal
diversities. High cycles of concentration resulted in high scaling and corrosion rates
and also had the result of similar community structure profiles. This research study
could facilitate the selection of optimised operational parameters for the re-use of
industrial process water (such as Primary Column Bottoms) as cooling water to
minimise fouling, scaling and corrosion.Thesis (M. Environmental Science (Water Science))--North-West University, Potchefstroom Campus, 2007
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Rivas, Perea Manuel Eduardo. "Assessment of fuel consumption reduction strategies on a gasoline turbocharged direct injection engine with a cooled EGR system." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/68497.
Full textAbstract:
[EN] This research work presents the study of a low pressure EGR loop influence on a SI gasoline turbocharged direct injection engine in steady and transient testing conditions, with an optimization process of the original engine calibration in order to minimize the engine fuel consumption when cooled EGR is introduced in steady testing conditions. The cooled EGR strategy was also evaluated operating in synergy with other fuel consumption reduction strategies, such as: lean burn, multi-injection, higher coolant temperature and in-cylinder induced swirl motion.
To fulfill the main objectives of this research work, firstly, a methodical process was followed, where a global methodology was first developed in order to obtain high accuracy engine tests, based on the experimental tools chosen that could comply with the requirements of the testing conditions, and the appropriate theoretical tools and procedure to post-process the tests performed. Secondly, a specific methodology was developed for each stage of the study and testing conditions, taking into account optimization processes or parametric tests in order to study the effect of a single parameter on engine's outputs or optimize an engine parameter in order to minimize the engine fuel consumption.
As a first stage of the study, a basic analysis of the impact of cooled EGR on the engine combustion, performance, air management and exhaust emissions is presented. Afterwards, an optimization of the combustion phasing in order to minimize the fuel consumption was performed, and therefore the potential of cooled EGR in order to reduce the engine fuel consumption was observed for low load, part load and full load engine conditions, for two different engine speeds. In addition, a study in transient conditions of the engine operating with cooled EGR was performed. NEDC cycles were performed with different EGR valve openings and therefore a comparison of different cooled EGR rates influence on the engine performance, air management and accumulated exhaust emissions was presented.
The second stage, consisted in a methodology developed to optimize the VVT setting and injection timing, for part load engine conditions, in order to maximize the cooled EGR potential to reduce engine fuel consumption. After this optimization, a synergy analysis of the optimum engine condition operating with cooled EGR and three other engine fuel consumption reduction strategies was performed. These strategies were tested to investigate and evaluate the potential of increasing the cooled EGR operational range to further decrease the engine fuel consumption. Furthermore, a basic study of the potential to reduce the engine fuel consumption and impact on combustion, air management and exhaust emissions of a lean burn strategy, in part load engine conditions, was presented as introduction of the final study of the cooled EGR strategy operating in synergy with the lean burn strategy in order to investigate the potential to control the exhaust emissions and reduce the engine fuel consumption.[ES] El objetivo de este trabajo de investigación es estudiar la influencia de un lazo de baja presión de EGR en las prestaciones de un motor de gasolina de encendido provocado turbosobrealimentado e inyección directa, en condiciones de ensayos estacionarios y transitorios, con un proceso de optimización de la calibración original del motor para minimizar el consumo de combustible del motor. La estrategia de "cooled EGR" fue también evaluada operando en sinergia con otras estrategias usadas para reducir el consumo de combustible del motor, entre ellas: mezcla pobre, múltiples inyecciones, operación a alta temperatura del fluido refrigerante del motor y movimiento de "swirl" inducido en el cilindro. Para cumplir con los objetivos mencionados, se siguió un proceso metódico donde previamente se desarrolló una metodología global para obtener resultados de indudable calidad, basados en el uso de herramientas experimentales que cumplieran con los requerimientos de las condiciones de ensayo, y las apropiadas herramientas teóricas y procedimiento para post-procesar los ensayos realizados. En segundo lugar, se desarrolló una metodología específica para cada etapa del estudio, teniendo en cuenta los procesos de optimización o estudios paramétricos que se pudieran realizar. Como primera etapa, se presenta un estudio básico del impacto del "cooled EGR" en la combustión, prestaciones, renovación de la carga y emisiones contaminantes del motor. Seguidamente, se procedió a la optimización del centrado de la combustión con la finalidad de minimizar el consumo de combustible del motor y poder analizar el potencial del "cooled EGR" como estrategia de reducción de consumo de combustible. El estudio presentado se realizó para baja, media y alta carga del motor con dos diferentes regímenes de giro del motor. Adicionalmente, se llevó a cabo un estudio del motor operando en condiciones transitorias con "cooled EGR". Se realizaron una serie de ensayos usando el ciclo NEDC como base y se probaron diferentes estrategias sencillas de control de la apertura de la válvula de EGR para analizar la influencia del "cooled EGR" en condiciones transitorias. La segunda etapa consiste en el desarrollo de una metodología para optimizar los parámetros del diagrama de distribución (VVT) y el inicio de inyección, para cargas medias del motor, con la finalidad de maximizar el potencial de reducción de consumo de combustible de la estrategia "cooled EGR". Una vez realizada la optimización, se llevó a cabo un estudio usando la configuración óptima encontrada, operando en sinergia con otras tres estrategias usadas para reducir el consumo de combustible del motor. Estas estrategias fueron evaluadas con la finalidad de incrementar el rango de operación de la estrategia "cooled EGR" para lograr reducir aún más el consumo de combustible del motor. Adicionalmente, se llevó a cabo un estudio básico sobre la influencia de operar con mezcla pobre en la combustión, prestaciones, renovación de la carga y emisiones contaminantes del motor, como introducción al último estudio llevado a cabo sobre la posibilidad de usar la estrategia de mezcla pobre en conjunto con la estrategia de "cooled EGR", con la finalidad de analizar el potencial de controlar las emisiones contaminantes y reducir el consumo de combustible del motor al mismo tiempo.
[CAT] L'objectiu d'este treball d'investigació és estudiar la influència d'un llaç de baixa pressió d'EGR en les prestacions d'un motor de gasolina d'encesa provocat turbosobrealimentat i injecció directa, en condicions d'assajos estacionaris i transitoris, amb un procés d'optimització del calibratge original del motor per a minimitzar el consum de combustible del motor. L'estratègia de "cooled EGR" va ser també avaluada operand en sinergia amb altres estratègies usades per a reduir el consum de combustible del motor, entre elles: mescla pobra, múltiples injeccions, operació a alta temperatura del fluid refrigerant del motor i moviment de `"swirl" induït en el cilindre. Per a complir amb els objectius mencionats, es va seguir un procés metòdic on prèviament es va desenrotllar una metodologia global per a obtindre resultats d'indubtable qualitat, basats en l'ús de ferramentes experimentals que compliren amb els requeriments de les condicions d'assaig, i les apropiades ferramentes teòriques i procediment per a post- processar els assajos realitzats. En segon lloc, es va desenrotllar una metodologia específica per a cada etapa de l'estudi, tenint en compte els processos d'optimització o estudis paramètrics que es pogueren realitzar. Com a primera etapa, es presenta un estudi bàsic de l'impacte del "cooled EGR" en la combustió, prestacions, renovació de la càrrega i emissions contaminants del motor. A continuació, es va procedir a l'optimització del centrat de la combustió amb la finalitat de minimitzar el consum de combustible del motor i poder analitzar el potencial del "cooled EGR" com a estratègia de reducció de consum de combustible. L'estudi presentat es va realitzar per a baixa, mitja i alta càrrega del motor amb dos diferents règims de gir del motor. Addicionalment, es va dur a terme un estudi del motor operand en condicions transitòries amb "cooled EGR". Es van realitzar una sèrie d'assajos usant el cicle NEDC com a base i es van provar diferents estratègies senzilles de control de l'obertura de la vàlvula d'EGR per a analitzar la influència del "cooled EGR" en condicions transitòries. La segona etapa consistix en el desenrotllament d'una metodologia per a optimitzar els paràmetres del diagrama de distribució (VVT) i l'inici d'injecció, per a càrregues mitges del motor, amb la finalitat de maximitzar el potencial de reducció de consum de combustible de l'estratègia "cooled EGR". Una vegada realitzada l'optimització, es va dur a terme un estudi usant la configuració òptima trobada, operant en sinergia amb altres tres estratègies usades per a reduir el consum de combustible del motor. Estes estratègies van ser avaluades amb la finalitat d'incrementar el rang d'operació de l'estratègia "cooled EGR" per a aconseguir reduir encara més el consum de combustible del motor. Addicionalment, es va dur a terme un estudi bàsic sobre la influència d'operar amb mescla pobra en la combustió, prestacions, renovació de la càrrega i emissions contaminants del motor, com a introducció a l'últim estudi dut a terme sobre la possibilitat d'usar l'estratègia de mescla pobra en conjunt amb l'estratègia de "cooled EGR", amb la finalitat d'analitzar el potencial de controlar les emissions contaminants i reduir el consum de combustible del motor al mateix temps.
Rivas Perea, ME. (2016). Assessment of fuel consumption reduction strategies on a gasoline turbocharged direct injection engine with a cooled EGR system [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68497
TESIS
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Michailidis, Antonis D. "Understanding complex CI-combustion strategies : an experimental investigation." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10957.
Full textAbstract:
Within this body of work several series of experiments will investigate the nature of complex combustion in an experimental single-cylinder engine emulating a modern passenger car size compression-ignition (CI) engine. Regimes of single, piloted single and piloted split-main injections will be tested and compared in terms of combustion characteristics, specific emission output and cyclic behaviour to determine how increased injection complexity affects the emissions and output of the modern CI engine. Through these tests, the effect of fuel-line stationary waves will be demonstrated and investigated, showing conclusively that optimised engine calibration is essential to account for injector-generated waves in any multiple injection scenario. This data will then be confirmed with a dedicated analysis using an injector rate measuring tube. The tests will then be expanded to include examination into the behaviour of injector needle-lift standard deviation over its operating cycle, in-cylinder pressure standard deviation behaviour and trends over the combustion cycle as well as IMEP variability. Through these tests a novel method to detect start of combustion will be proposed and compared to conventional methods. Low temperature combustion (LTC) will be tested under incremental injection complexity. Tests will be optimised for combustion phasing and injection pressure, with a view to analysis of emissions, output and cyclic behaviour to establish whether the knowledge gained about conventional combustion holds true under LTC. Optimization of engine parameters will be shown to result in easier to implement LTC regimes with superior emissions characteristics. Finally, LTC tests will be expanded to include 30% and 50% by volume gas-to-liquid fuel (GTL) blends in order to determine whether fuel characteristics further influence emissions, output and cyclic behaviour in LTC through complex injection regimes. How GTL-blend ratio affects trends in emissions and cyclic behaviour will also be examined and compared to conventional diesel fuel.
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Lacroix, Maxime. "Optimisation et caractérisation d’un nouveau support catalytique à base de mousses alvéolaires de β-SiC : Application à la synthèse de Fischer-Tropsch." Université Louis Pasteur (Strasbourg) (1971-2008), 2008. https://publication-theses.unistra.fr/restreint/theses_doctorat/2009/LACROIX_Maxime_2009.pdf.
Full textAbstract:
La réaction catalytique appelée Synthèse de Fischer Tropsch (SFT) permet de transformer du gaz de synthèse, i. E. Mélange de H2 et de CO, en une distribution d’hydrocarbures (CnH2n+2 avec 1 < n < 60-100), plus ou moins saturés et plus ou moins oxygénés. La voie GTL (Gas-To-Liquids) incluant la SFT, est donc une opportunité permettant de transformer les gaz de torchage des puits de pétrole et/ou les stranded gas en produits utilisables dans les moteurs automobiles ou d’avion. Les catalyseurs utilisés jusqu’alors dans les procédés Fischer-Tropsch sont composés de cobalt ou de fer déposés sur alumine ou silice, et, bien que présentant de bonnes performances, ceux-ci sont fortement limités par la forte exothermicité de la réaction, qui induit une élévation importante de la température à la surface du catalyseur et donc une sélectivité vers les produits désirés relativement faible. Dans ce contexte, le carbure de silicium (β-SiC) a été proposé comme support de remplacement aux supports oxydes classiques de manière à mieux évacuer la chaleur dégagée par la réaction et conserver ainsi une meilleure sélectivité de la réaction même à haute conversion. De plus, il a été proposé d’étudier l’impact de la morphologie du support catalytique (extrudés, mousses alvéolaires) sur la réaction de Fisher Tropsh. Il s’est avéré que les propriétés intrinsèques des supports alvéolaires à base de β-SiC (bonne conductivité thermique effective, faible perte de charge, etc…) laissent entrevoir de nouvelles perspectives pour la réaction de Fischer Tropsch en lit fixe. Lors de nos travaux, le carbure de silicium en tant que support a montré de meilleures activités que l’alumine, que ce soit sous forme d’extrudés ou sous forme de mousse. En effet, des emballements thermiques ont été observés sur alumine alors que l’utilisation du β-SiC a permis un meilleur contrôle des gradients de température dans le lit catalytique et ainsi une meilleure sélectivité de la réaction catalytique. Une étude approfondie a permis d’estimer l’influence de la charge en phase active sur les performances catalytiques du catalyseur supportés sur mousses de β-SiC. Un modèle géométrique simple a été développé afin d’estimer la perte de charge induite par les supports de type alvéolaire. Une corrélation avec les packed bed a été développée et s’est montrée capable, grâce à la relation d’Ergun, d’estimer les pertes de charge qu’engendre le passage d’un fluide dans la structure des mousses. Enfin, une étude sur les écoulements biphasique au sein des structure type mousse a permis de mettre en évidence les fortes retentions liquides induites par ce type de support en comparaison avec les lits classiquesThe catalytic Fischer Tropsch Synthesis (FTS) enables the transformation of synthetic gas, i. E. Mixture of H2 and CO, into a distribution of hydrocarbons (CnH2n+2 with 1 < n < 60-100), more or less saturated and more or less oxygenated. The Gas to Liquids way, including FTS, is consequently an opportunity allowing the transformation of the flared and/or stranded gas into liquid hydrocarbons for car or plane fuelling. This could first reduce the CO2 release in the atmosphere and secondly increase the oil resources by the transformation of natural gas. The classical catalysts used in Fischer-Tropsch processes are composed of cobalt or iron supported on alumina or silica, and, although they present good performances, they are highly constricted by the high exothermicity of the reaction inducing high temperature on the catalyst surface, leading to low selectivity towards desired products (i. E. Long chained parafins). In this context, silicon carbide (β-SiC) has been proposed as replacement support to alumina and silica in order to better evacuate the heat released by the reaction and thus keeping higher selectivity even at high conversion levels. Moreover, always in order to optimize the process, the impact of the catalytic support morphology (extrudates, cellular foams) on the Fischer-Tropsch reaction has been studied. It appeared that the intrinsic properties of the cellular supports (high effective thermal conductivity, low pressure drops) could let foresee new perspectives in the fixed bed FT reaction. In this work, silicon carbide as catalyst support revealed to be far more attractive than alumina both in the form of extrudates or cellular foams. Indeed, thermal runaway have been observed on alumina whereas the use of β-SiC allowed better control of the temperature and thus better selectivity towards C5+ products. A study on the influence of the active phase charge on the catalytic performances of the catalyst supported on β-SiC foams has been performed. A simple geometric model of the foam as been developed in order to estimate the pressure drop induced by the cellular supports. A correlation with classical packed beds was showed to be able to model the pressure loss induced by a gaseous flow in the cellular material. Finally, a study on the biphasic behaviour of β-SiC foams has evidenced higher liquid hold-ups compared to classical packed beds. The influence of this property on the FT reaction has here not been made and will be the subject of a next study
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Pinto, Cátia. "VineMicrobiome : Une analyse approfondie de la communauté microbienne naturelle de Vitis vinifera Vitis vinifera microbiome: from basic research to technological development Unravelling the diversity of grapevine microbiome Wine fermentation microbiome: a landscape from different Portuguese wine appellations The effects of grapevine trunk diseases (GTDs) on vine physiology." Thesis, Reims, 2017. http://www.theses.fr/2017REIMS045.
Full textAbstract:
La vigne est une culture fruitière largement cultivée, qui abrite naturellement un microbiome complexe, i.e. colonisée par des microorganismes neutres, phytopathogènes ou bénéfiques. Parmi les phytopathogènes, ceux associés aux maladies du bois (MDB) induisent des maladies très destructrices, et les traitements disponibles pour les contrôler ont actuellement une efficacité partielle. Les microorganismes bénéfiques (BCA) peuvent jouer un rôle spécifique dans la protection des plantes contre les phytopathogènes et le défi actuel est de comprendre comment ces microorganismes interagissent avec les plantes et leur potentiel biotechnologique pour le développement de stratégies innovantes. Dans ce contexte, l'objectif de cette étude était d'abord de caractériser les communautés microbiennes associées à la vigne tout au long de son cycle végétatif et, d'autre part, de mieux comprendre les interactions entre la vigne- BCA – MDB. Pour cela, deux potentiels BCA isolés de la vigne ont été testés contre des espèces de Botryosphaeriaceae et leur potentiel de colonisation, l'induction de mécanismes de défense dans la vigne, en présence ou non de D. seriata (F98.1), ont été caractériser ainsi que l’analyse de leur génome.Les résultats ont montré que le microbiome de la vigne était très dynamique au cours de son cycle végétatif. Comme prévu, la biodiversité microbienne était plus élevée dans les sols, et les communautés variaient entre le sol et les feuilles. Une proportion de communautés microbiennes était similaire dans les sols et les feuilles, ce qui suggère l'existence d'un microbiome commun. Plusieurs isolats ont été obtenus à partir de vignes qui appartenaient principalement aux genres Bacillus, Streptomyces et Aureobasidium. Certains d'entre eux ont considérablement diminué la croissance du mycélium de plusieurs espèces de Botryosphaeriaceae, telles que Streptomyces sp. Fito_S127B et A. pullulans Fito_F278 qui ont été sélectionnés comme BCA. Ces souches ont montré qu'elles produisaient une gamme élevée d'enzymes extracellulaires importantes pour le biocontrôle et ont pu coloniser avec succès la vigne : Fito_S127B était une épiphyte du système racinaire de la vigne, tandis que Fito_F278 pouvait coloniser l’ensemble de la plante, des racines aux feuilles. L'inoculation artificielle des tiges avec D. seriata F98.1 a montré que la longueur des nécroses causées par l'agent pathogène a été significativement réduite par Fito_S127B, contrairement à Fito_F278 qui était moins efficace. De plus, ces BCAs sont capables d’activer certaines réponses de défense de la vigne, permettant une réponse plus rapide et plus forte de la plante contre le pathogène. L'analyse du génome a également montré que ces souches sont une source des composés bioactifs, importants pour le contrôle biologique.Dans l'ensemble, cette étude a apporté de nouvelles connaissances sur la structure des communautés microbiennes de la vigne et leurs interactions. De plus, elle a confirmé que la vigne est une source naturelle de microorganismes prometteurs pour une gestion biologique des MDB et qu'ils peuvent promouvoir les réponses de défense des plantes. Ainsi, ces résultats fournissent non seulement une meilleure compréhension des interactions entre la vigne et les BCAs-MDB, mais aussi une forte contribution à la future stratégie de gestion des MDB.Mots-clés : microbiome de la vigne, MDB, D. seriata, microorganismes bénéfiques, Fito_S127B, Fito_F278, colonisation de la vigne, mécanismes de défense, protectionVitis vinifera L. is a widely cultivated fruit crop, that naturally harbours a complex microbial ecosystem or plant microbiome, such as neutral, phytopathogenic or beneficial microorganisms. Among phytopathogens, those implied in Grapevine trunk diseases (GTDs) are responsible for the most destructive diseases worldwide, and currently no highly effective treatments are available. Beneficial microorganisms (BCAs) may play specific roles on plant protection against phytopathogens though, the present challenge is to understand how such microorganisms interact with plant and their biotechnological potential for development of innovation strategies. In this context, the aim of this study was firstly to unveil the microbial communities associated with grapevine along its growth cycle and, secondly, to better understand the grapevine – BCAs – GTDs interactions. For this, two potential BCAs isolated from grapevine were tested against Botryosphaeriaceae species and then deep characterized, namely for their colonisation potential, induction of defence mechanisms in grapevine, in the presence or not of D. seriata (F98.1) and their genome analysis. Results showed that grapevine microbiome was very dynamic along the growth cycle. As expected, the microbial biodiversity was higher in soils, and these microbial communities differed significantly from those of leaves. A proportion of microbial communities was shared within soils and leaves, suggesting the existence of a core microbiome. Several isolates were then obtained from grapevine which mostly belonged to Bacillus, Streptomyces and Aureobasidium genera. Some of them significantly decreased in vitro the mycelium growth of several Botryosphaeriaceae species, such as Streptomyces sp. Fito_S127B and A. pullulans Fito_F278 which were highly effective and thus selected as potential BCAs. These strains showed to produce a high range of extracellular enzymes with biocontrol value, and were able to successfully colonize grapevine: Fito_S127B was an epiphyte from rhizosphere, while Fito_F278 colonised grapevine from roots to leaves. The artificial inoculation of green stems with D. seriata F98.1 on cutting plants showed that the necrotic lesions length caused by the pathogen was significantly reduced by Fito_S127B, in contrast to Fito_F278 which was less effective. Furthermore, these BCAs activated some specific defence responses of grapevine, allowing a more rapid and solid response of plant against the pathogen. The genome analysis also showed that these BCAs strains are an important source of bioactive compounds of biocontrol value. Overall, this study brought new insights on the structure of microbial communities of grapevine and their interactions. Moreover, highlighted that grapevine is a natural source of microorganisms with a promising biocontrol against GTDs, and that they can promote plant defense responses. Thus, these findings provide not only a better understand of the grapevine- BCAs- GTDs interactions but also a strong contribution to future GTDs management strategy. Key-words: Grapevine microbiome, GTDs, D. seriata, beneficial microorganisms, Fito_S127B, Fito_F278, grapevine colonisation, plant defence mechanisms, grapevine protection
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Saidane, Lamia. "Synthèses Fischer Tropsch : Optimisation des paramètres réactionnels en mode lit fixe." Strasbourg, 2009. http://www.theses.fr/2009STRA6150.
Full textAbstract:
Dans le procédé GTL, la SFT est l’étape qui permet de transformer le syngas en hydrocarbures liquides. L’intérêt d’utiliser le Co/SiC a été démontré. Notre travail consiste à étudier l’influence des paramètres réactionnels : Tréduction, promoteurs ou nature du support sur l’activité. La taille de cobalt, sa réductibilité ainsi que sa cristallinité sont suivies par diverses techniques de caractérisation: DRX, TPR et MEB. Le dopage du Co/SiC avec des traces de Ru a permis d’améliorer sensiblement la dispersion des particules métalliques. Une étude comparative sur des supports (β−SiC) : mousse, extrudés et grains a été réalisée. Afin de mettre en évidence l’inertie chimique et la conductivité thermique du SiC, nous l’avons comparé avec des mousses d’alumine et alumine/SiC. En termes de respect de l’environnement, l’idée directrice de notre travail était de régénérer et recycler le catalyseur. Ceci représente un avantage non négligeable du β−SiC par rapport aux supports conventionnelsIn the GTL process, the FTS is the step which transforms the syngas into liquid HC. In catalysis, the interest of using Co/SiC was demonstrated. This work consists in studying the influence of parameters: Treduction, promoters or the nature of the support on the activity. Modifications of the active phase particles size, its reducibility as well as its crystallinity are followed by diverse characterization techniques: XRD, TPR and SEM. The Ru effect on the Co/SiC system enhanced the Co dispersion and consequently the activity. In order to illustrate the best macroscopic shape of β−SiC (foam, pellets and powder), a comparative study on supports was also realized. A second study deals with the chemical nature of supports eg. SiC, Al2O3/SiC and Al2O3. In term of environmental protection, the base idea of this work was to enhance the catalyst life time by its regeneration and its recycling
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Pinto, Cátia Carvalho. "Vine microbiome: a deep analysis of the natural microbial community of Vitis vinifera L." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/22642.
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Doutoramento em BiologiaA vinha, Vitis vinifera L., abriga naturalmente um ecossistema microbiano complexo ou microbioma, tais como microrganismos neutros, fitopatogenos ou benéficos. Entre os fitopatogenos, aqueles implicados nas doenças do lenho da videira (GTDs) são responsáveis pelas doenças mais destrutivas, para o qual não existem tratamentos altamente eficazes. Por outro lado, os microrganismos benéficos (BCAs) podem desempenhar papéis específicos na proteção das plantas contra estes agentes. Neste sentido, o atual desafio consiste em compreender como estes BCAs interagem com a planta e qual o seu potencial biotecnológico para o desenvolvimento de novas estratégias de proteção da planta. Neste contexto, o objetivo deste estudo visou primeiramente analisar profundamente as comunidades microbianas associadas com a videira ao longo do seu ciclo de crescimento até à fermentação do vinho e, em seguida, compreender as interações entre vinha-BCAs-GTDs. Para isso, dois potenciais BCAs isolados da videira foram testados contra diferentes espécies de Botryosphaeriaceae e, em seguida, caracterizados relativamente ao seu potencial de colonização, de indução dos mecanismos de defesa da planta, na presença ou não do fitopatogeno (D. seriata F98.1), e análise do respetivo genoma. Os resultados demonstraram que o microbioma da videira é altamente dinâmico ao longo do ciclo de crescimento da planta. Como esperado, a biodiversidade microbiana é maior nos solos, e estas comunidades diferem significativamente daquelas presentes nas folhas e mostos vínicos. Contudo, alguns destes microrganismos são partilhados, o que sugere a existência de um microbioma comum. Diferentes isolados foram obtidos, pertencendo na sua maioria ao género Bacillus, Streptomyces e Aureobasidium. A videira é naturalmente colonizada por microrganismos com potencial antagonista de várias espécies de Botryosphaeriaceae. Entre estes, destacam-se os isolados Streptomyces sp. Fito_S127B e A. pullulans Fito_F278, que foram selecionados como potenciais BCAs. Estes microrganismos produzem diferentes enzimas extracelulares importantes para as atividades de controlo biológico e são capazes de colonizar com sucesso a videira: Fito_S127B coloniza a rizosfera, enquanto que Fito_F278 coloniza desde as raízes até às folhas. A inoculação artificial da videira com D. seriata F98.1 mostrou que o comprimento das lesões necróticas causadas pelo fitopatogeno são significativamente reduzidas na presença de Fito_S127B. Em contrapartida, a espécie Fito_F278 foi menos eficaz. Estes BCAs ativaram algumas respostas de defesa específicas da videira, o que permitiu uma resposta mais rápida e sólida da planta contra o agente fitopatogénico. A análise do genoma destes microrganismos permitiu averiguar diferentes genes que codificam compostos bioativos altamente importantes para o controlo biológico. De uma forma geral, este estudo abrange novos conhecimentos relativos à estrutura das comunidades microbianas associadas à videira e às suas interações. Para além disso, destaca que a videira ostenta naturalmente microrganismos com um controlo biológico promissor e que estes podem promover respostas de defesa importantes na planta. Neste sentido, estes resultados permitem não só uma melhor compreensão das interações da videira-BCAs-GTDs, mas também representam um forte contributo e avanço para o desenvolvimento de novas estratégias da gestão da vinha, tais como as doenças do lenho.
Vitis vinifera L. is a widely cultivated fruit crop, that naturally harbours a complex microbial ecosystem or plant microbiome, such as neutral, phytopathogenic or beneficial microorganisms. Among phytopathogens, those implied in Grapevine Trunk Diseases (GTDs) are responsible for the most destructive diseases worldwide, and currently no highly effective treatments are available. Beneficial microorganisms (BCAs) may play specific roles on plant protection against phytopathogens though, the present challenge is to understand how such BCAs interact with plant and their biotechnological potential for development of innovation strategies. In this context, the aim of this study was firstly to unveil the microbial communities associated with grapevine along its growth cycle until wine fermentation and, secondly, to better understand the grapevine – BCAs – GTDs interactions. Two potential BCAs isolated from grapevine were tested against Botryosphaeriaceae species and then deep characterized, namely for their colonisation potential, induction of defence mechanisms in grapevine, in the presence or not of D. seriata F98.1, and their genome analysis. Results showed that grapevine microbiome was very dynamic along the growth cycle. As expected, the microbial biodiversity was higher in soils, and these microbial communities differed significantly from those of leaves and wine musts. A proportion of microbial communities was shared within these structures, suggesting the existence of a core microbiome. Several isolates were then obtained from grapevine which mostly belonged to Bacillus, Streptomyces and Aureobasidium genera. Some of them significantly decreased in vitro the mycelium growth of several Botryosphaeriaceae species, such as Streptomyces sp. Fito_S127B and A. pullulans Fito_F278 which were highly effective and thus selected as potential BCAs. These strains showed to produce a high range of extracellular enzymes with biocontrol value, and were able to successfully colonize grapevine: Fito_S127B was an epiphyte from rhizosphere, while Fito_F278 colonised grapevine from roots to leaves. The artificial inoculation of green stems with D. seriata F98.1 on cutting plants showed that the necrotic lesions length caused by the pathogen was significantly reduced by Fito_S127B, in contrast to Fito_F278, which was less effective. Furthermore, these BCAs activated some specific defence responses of grapevine, allowing a more rapid and solid response of plant against the pathogen. The genome analysis also showed that these BCAs strains are an important source of bioactive compounds of biocontrol value. Overall, this study brought new insights on the structure of microbial communities of grapevine and their interactions. Moreover, highlighted that grapevine is a natural source of microorganisms with a promising biocontrol against GTDs, and that they can promote plant defence responses. Thus, these findings provide not only a better understand of the grapevine- BCAs- GTDs interactions but also a strong contribution to future GTDs management strategy.
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Comblet, Fabrice. "Détection, localisation et identification de cibles radar par imagerie électromagnétique bistatique." Phd thesis, Université de Bretagne occidentale - Brest, 2005. http://tel.archives-ouvertes.fr/tel-00011931.
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L'objectif de cette thèse est de développer, caractériser et analyser l'imagerie radar en configuration bistatique. Dans le cadre de notre étude, nous nous plaçons dans le cas général d'une configuration bistatique sans condition sur la configuration d'acquisition. Nous avons alors développé un algorithme de reconstruction d'images tenant compte des polarisations d'émission et de réception. Ainsi, nous avons pu caractériser les images obtenues et donner l'expression des résolutions d'une image bistatique en fonction de la configuration d'acquisition. Ensuite, nous avons étudié les images bistatiques reconstruites lors de l'observation de cibles complexes ainsi que celles obtenues lors de la détection de cibles sur une surface océanique afin de les comparer avec celles d'une configuration monostatique. Les résultats ainsi obtenus permettent de valider l'intérêt de la configuration bistatique et de présenter les nouvelles perspectives qu'offre ce sujet de recherche en imagerie radar.
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Bricteux, Caroline. "Régulation de l'Internet par les noms de domaine. Le régime juridique et institutionnel de l'ICANN." Doctoral thesis, Universite Libre de Bruxelles, 2019. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/284381.
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La régulation de l’Internet constitue depuis toujours un défi pour le droit :le « réseau des réseaux » a été conçu dans un esprit de connectivité universelle, avec la volonté que chaque utilisateur intéressé puisse y relier son ordinateur et accéder aux informations disponibles en ligne, sans que celles-ci soient altérées en fonction du lieu de connexion et donc sans tenir compte d’éventuelles règles nationales, régionales ou internationales. S’il s’inscrit ainsi en porte-à-faux avec les principes fondamentaux du droit national et international, fondés sur la souveraineté des États et sur des frontières géographiques bien établies, l’Internet n’est pas pour autant un espace anarchique. Il constitue plutôt un terrain propice à l’émergence de nouveaux régulateurs et à l’expérimentation de nouvelles formes de normativité. L’espace virtuel global repose en effet sur une architecture physique et informatique qui peut être modelée et sollicitée à des fins de régulation des flux d’informations en ligne. Dans cette optique, notre thèse se penche sur le Domain Name System (DNS), le système de nommage et d’adressage de l’Internet qui assure les correspondances entre les noms de domaine intelligibles pour les humains et les adresses IP numériques utilisées par les ordinateurs pour communiquer entre eux. La structure hiérarchique de cet annuaire global en fait une cible de choix pour ceux qui aspirent à un contrôle centralisé du réseau et des informations qu’il véhicule. Le DNS est administré depuis 1998 par une organisation globale atypique, l’Internet Corporation for Assigned Names and Numbers (ICANN), constituée sous la forme d’une société privée de droit californien, investie de ses compétences en vertu de contrats avec le gouvernement des États-Unis et caractérisée par un modèle de gouvernance multipartite mobilisant des représentants du secteur privé, de la société civile et des gouvernements. Par une étude pragmatique des actes juridiques produits par l’ICANN en vue d’attribuer de nouvelles extensions de noms de domaine génériques – à côté du fameux .com et en parallèle des extensions nationales telles le .be – nous démontrons que l’organisation ne se cantonne pas à une mission essentiellement technique mais se profile, à son corps défendant, comme un régulateur global des contenus en ligne. Nous mettons en évidence, d’une part, que les normes globales édictées par l’ICANN pour justifier le rejet des candidatures indésirables ne visaient pas seulement les termes proposés comme nouvelles extensions mais aussi les conditions d’exploitation envisagées par les candidats, afin d’assurer ex ante la licéité et la qualité des informations présentées dans les futurs domaines. Nous montrons, d’autre part, que l’ICANN a été amenée, sous la pression des gouvernements, à investir ses sous-contractants, les registres et registraires de noms de domaine, d’obligations d’intérêt public relatives au contenu des sites web auxquels leurs noms de domaine donnent accès, en vue de lutter contre les activités abusives et de protéger les consommateurs. Nous démontrons que l’ICANN a ainsi renforcé, sous sa supervision, le rôle des intermédiaires du DNS en tant que points de contrôle du contenu posté en ligne et pointons les dérives potentielles de cette évolution, qui n’est accompagnée d’aucun garde-fou pour préserver la liberté d’expression en ligne.Doctorat en Sciences juridiques
info:eu-repo/semantics/nonPublished
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HUANG, GI-FANG, and 黃啟芳. "GTD analysis of electromagnetic scattering by convex surface." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/12728816393041113098.
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Hamad, Natalie. "Safety and Techno-Economic Analysis of Solvent Selection for Supercritical Fischer-Tropsch Synthesis Reactors." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10370.
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Fisher-Tropsch Synthesis is a primary pathway for gas-to-liquid technology. In order to overcome commercial problems associated with reaction and transport phenomena, the use of supercritical solvents has been proposed to increase chemical conversion and improve temperature control. One of the major challenges in designing the supercritical FTS systems is the solvent selection. Numerous alternatives exist and should be screened based on relevant criteria. The main aim of the thesis was to develop a safety metric that can be incorporated in the selection of an optimal supercritical solvent or a mixture of solvents. The objective was to minimize the cost while satisfying safety constraints or to establish tradeoffs between cost and safety. Hydrocarbons from C3 to C9 were identified as feasible solvents for FTS purposes. The choice of these solvents is dependent on their mixture critical temperature and pressure requirements that need to be satisfied upon entry into the FTS reactor. A safety metric system was developed in order to compare the risk issues associated with using the aforementioned solvents. In addition, an economic analysis of using the different solvents was performed. Finally, a case study was solved to illustrate the use of the proposed metrics and the selection of solvents based on safety and techno-economic criteria.
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Black, Brodie Gene 1986. "Monetizing stranded gas : economic valuation of GTL and LNG projects." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-05-1342.
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Globally, there are significant quantities of natural gas reserves that lie economically or physically stranded from markets. Options to monetize such reserves include Gas to Liquids (GTL) and Liquefied Natural Gas (LNG) technologies. GTL is a unique monetization option that brings natural gas products to crude oil markets. This technology is commercially immature, appears to have attractive market potential, requires substantial capital investments, and has uncertain operating costs and revenue generation. LNG is a more established monetization option. Project economics for the two technologies are reviewed, as well as literature evaluating such for either or both. Discounted cash flow models are studied for two project scenarios, and results are discussed and compared. The modeling effort seeks to inform the decision to invest in GTL or LNG for the monetization of a stranded gas reserve.text
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Chou, Chun-Wei, and 周俊瑋. "A systolic array based GTD processor with a parallel algorithm." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/643kx6.
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碩士國立交通大學
電子工程學系 電子研究所
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Generalized triangular decomposition (GTD) has been found to be useful in the field of signal processing, but the feasibility of the related hardware has not yet been established. This paper presents (for the first time) a GTD processor architecture with a parallel algorithm. The proposed parallel GTD algorithm achieves an increase in speed of up to 1.66 times, compared to the speed of its conventional sequential counterpart for an 8x8 matrix. For hardware implementation, the proposed reconfigurable architecture is capable of computing singular value decomposition (SVD), geometric mean decomposition (GMD), and GTD for matrix sizes from 1x1 to 8x8. The proposed GTD processor is composed of 16 processing cores in a heterogeneous systolic array. Computations are distributed over area-efficient coordinate rotation digital computers (CORDICs) to achieve a high throughput. To establish the validity of the concept, a GTD processor was designed and implemented. The latency constraint of 16 us specified in the 802.11ac standard is adopted for the hardware realization. The proposed design achieves a maximum throughput of 83.3k matrix/sec for an 8x8 matrix at 112.4 MHz. The estimated power and core area are 172.7 mW and 1.96 mm^2, respectively, based on standard 90 nm CMOS technology.