Dissertations / Theses on the topic 'Direct reduction'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Direct reduction.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Wang, Tao. "Novel iron ore direct reduction process using biomass." Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0297.
Full textSubstituting fossil carbon with biogenic carbon from biomass could considerably reduce the contribution of the steel industry to global warming. The objective of this thesis was to introduce and analyse an innovative ironmaking process, called BIORED (biomass-based iron ore reduction). In this process, iron ore pellets and granular biomass are loaded together at the top of a vertical shaft furnace. The ore is reduced by CO produced from the in-situ gasification of the biomass (Boudouard reaction). The devolatilisation and gasification kinetics of the selected biomass, charcoal, were determined from thermogravimetry experiments. These kinetics were modelled by the scheme of independent parallel reactions and the Langmuir-Hinshelwood equation, respectively. We used an existing numerical model of a gas-based direct reduction process to create a new one that considers two solids and the biomass-related reactions. The model results show that the gasification takes place at the bottom of the BIORED reactor, while the reduction of the iron ore occurs step-wisely, with the reduction of wustite to metallic iron being the slowest. The degree of metallisation is satisfactory and the top gas (CO-CO2 mixture) could be recycled to reuse CO and save energy. We developed a specific experimental protocol for the validation of the model. The experimental results satisfactorily agree with the numerical ones. Eventually, the potential industrial development of the BIORED process in different regions of the world was assessed, and a life cycle assessment of a new steelmaking route based on BIORED process showed a considerable reduction in CO2 emissions (96% less) and most other environmental impacts, compared to the conventional Blast Furnace-Basic Oxygen Furnace route
Yasuda, Kouji. "Direct electrolytic reduction of solid SiO2 to Si in molten chlorides." Kyoto University, 2005. http://hdl.handle.net/2433/144446.
Full text0048
新制・課程博士
博士(エネルギー科学)
甲第11840号
エネ博第116号
新制||エネ||30(附属図書館)
23600
UT51-2005-K506
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 尾形 幸生, 教授 八尾 健, 教授 萩原 理加
学位規則第4条第1項該当
Kazemi, Mania. "Fundamental Studies Related to Gaseous Reduction of Iron Oxide." Doctoral thesis, KTH, Materialvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-191021.
Full textQC 20160823
Wessey, Napoleon. "The evaluation of the industrial potential of Nigerian direct reduction steelmaking slag." Thesis, University of Hull, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442228.
Full textAffadu-Danful, George. "Immobilization of Gold Nanoparticles on Nitrided Carbon Fiber Ultramicroelectrodes by Direct Reduction." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etd/3446.
Full textDongchen, Wang. "Effect of Density on the Reduction of Fe2O3 Pellets by H2-CO Mixtures." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-100933.
Full textBardhipur, Seema. "Modeling the Effect of Green Infrastructure on Direct Runoff Reduction in Residential Areas." Cleveland State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=csu1494345249222244.
Full textMotsoeneng, Rapelang Gloria. "Advanced oxygen reduction reaction catalysts/material for direct methanol fuel cell (dmfc) application." University of the Western Cape, 2014. http://hdl.handle.net/11394/4365.
Full textFuel cells are widely considered to be efficient and non-polluting power source offering much higher energy density. This study is aimed at developing oxygen reduction reactions (ORR) catalysts with reduced platinum (Pt) loading. In order to achieve this aim, monometallic Pd and Pt nanostructured catalysts were electrodeposited on a substrate (carbon paper) by surface limited redox replacement using electrochemical atomic layer deposition (ECALD) technique. Pd:Pt bimetallic nanocatalysts were also deposited on carbon paper. Pd:Pt ratios were (1:1, 2.1 and 3:1). The prepared mono and bimetallic catalysts were characterized using electrochemical methods for the ORR in acid electrolyte. The electrochemical characterization of these catalysts includes: Cyclic Voltammetry (CV) and linear sweep voltammetry (LSV). The physical characterization includes: scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) for Morphology and elemental composition, respectively. The deposition of copper (Cu) on carbon paper was done by applying a potential of -0.05 V at 60s, 90s and 120s. 8x cycles of Pt or Pd showed better electrochemical activity towards hydrogen oxidation reaction. Multiples of eight were used in this work to deposit Pt: Pd binary catalyst. Cyclic voltammetry showed high electroactive surface area for Pt24Pd24/Carbon-paper while LSV showed high current density and positive onset potential. HRSEM also displayed small particle size compared to other Pt:Pd ratios.
BRANDAO, GEISAMANDA PEDRINI. "MERCURY DETERMINATION IN GASOLINE BY COLD VAPOR AND AAS WITH DIRECT REDUCTION IN MICROEMULSION." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=4945@1.
Full textFoi estudada a determinação de mercúrio em gasolina pela técnica do vapor frio, com redução em meio orgânico e de solução de três componentes (microemulsão). Foram utilizadas várias metodologias empregando a técnica de geração de vapor frio e detecção em espectrômetro de absorção atômica, a saber: determinação direta em gasolina; determinação direta em gasolina estabilizada na forma de microemulsão, com e sem pré-concentração em rede de ouro; e determinação direta em gasolina estabilizada na forma de microemulsão utilizando uma armadilha para vapores de gasolina antes da pré-concentração em rede de ouro. Analisando os resultados, foi verificado que a determinação de mercúrio em gasolina estabilizada na forma de microemulsão fornece medidas mais repetitivas do que em gasolina in natura; além disso, foi observada a necessidade de utilizar pré-concentração em rede de ouro, devido aos baixos níveis de mercúrio em gasolina; entretanto, foi detectado que os vapores de gasolina envenenam o ouro. Dentre as armadilhas estudadas para evitar o envenenamento do ouro, foi escolhida a armadilha com solução de K2Cr2O7/H2SO4, na qual, os vapores rovenientes do frasco de reação foram borbulhados e o Hg0, oxidado; posteriormente, a solução foi reduzida com SnCl2/ H2SO4 e os vapores enviados para a rede de ouro. Assim, os resultados indicaram que o método para determinação de mercúrio total em gasolina, no qual o mercúrio é reduzido diretamente da gasolina como microemulsão, utilizando armadilha de K2Cr2O7/H2SO4 antes da pré-concentração em ouro, com detecção por CV-AAS, é recomendado. Após uma otimização multivariada, curvas analíticas apresentaram coeficientes de correlação de até 0,9999 com uma massa característica correspondente de 2ng de mercúrio. O limite de detecção obtido por este método foi de 0,10 ng/mL (0,14 ng/g).
The mercury determination in gasoline by cold vapor and AAS, with reduction in organic liquids and in solution of three components (microemulsion)was studied. Some methodologies were used, with cold vapor generation and atomic absorption spectrometer, to know: direct determination in gasoline; direct determination in gasoline stabilized as microemulsion, with and without preconcentration in gold; and direct determination in gasoline stabilized as microemulsion using a trap for gasoline vapors before the preconcentration in gold. Analyzing the results, it was verified that the measurements from the gasoline stabilized as microemulsion supplies more repetitive readings than the gasoline in nature; moreover, it was observed that is necessary to use preconcentration in gold, due to the lower mercury levels in gasoline; however, it was detected that the gasoline vapors poison the gold. Amongst the studied traps to prevent the poisoning of the gold, the trap with solution of K2Cr2O7/ H2SO4 was chosen, in which, the vapors proceeding from the reaction bottle had been bubbled and the Hg0, oxidated; later, the solution was reduced with SnCl2/ H2SO4 and vapors sent to the gold. Thus, the results had indicated that the method for total mercury determination in gasoline, in which the mercury is reduced directly from the gasoline as microemulsion, using the K2Cr2O7/H2SO4 trap before the preconcentration in gold, with CV-AAS detection, is recommended. After multivariate optimization analytical curves showed coefficients of correlation as good as 0.9999 with a corresponding characteristic mass of 2ng of mercury. The limit of detection obtained for this method was 0.10 ng/mL (0.14 ng/g).
Luedtke, Kerstin. "Transcranial direct current stimulation for the reduction of chronic non-specific low back pain." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5248/.
Full textPetersen, Shaheeda. "Investigation of the hot deformation of sintered titanium compacts produced from direct reduction powder." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/11748.
Full textThe focus of this study was the use of powder metallurgy to produce low cost titanium with comparative mechanical properties to wrought titanium. The objectives of this investigation was to produce sintered titanium compacts that represented metal made by the Direct Powder Rolling method. The critical strain (ɛC) required to induce recrystallization following deformation was determined by hot compressing wrought titanium samples. Finally sintered titanium samples were hot compressed at ɛC and the changes to the microstructure, porosity and mechanical properties was assessed.
Wu, Yunyun. "Effect of different parameters on the direct reduction processes of natural iron ores from Uganda." Thesis, KTH, Materialvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-93455.
Full textvon, Deak Dieter G. "Heteroatom-containing Carbon Nanostructures as Oxygen Reduction Electrocatalysts for PEM and Direct Methanol Fuel Cells." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313085489.
Full textPeñaranda, Cebrián Roberto. "Improvement of interconnection networks for clusters: direct-indirect hybrid topology and HoL-blocking reduction routing." Doctoral thesis, Universitat Politècnica de València, 2018. http://hdl.handle.net/10251/79550.
Full textHoy en día, los clústers de computadores son usados para solucionar grandes problemas. Estos clústers aprovechan la gran cantidad de nodos de computación para ofrecer un alto grado de paralelización. Para conectar todos estos nodos de computación, se utilizan redes de interconexión de altas prestaciones capaces de manejar de forma eficiente el tráfico generado. Estas redes tienen diferentes parámetros de diseño que definen su comportamiento, de los cuales podríamos destacar dos: la topología y el algoritmo de encaminamiento. La topología de una red de interconexión define como se conectan sus componentes, mientras que el algoritmo de encaminamiento determina la ruta que un paquete debe tomar desde su origen hasta su destino. Las topologías más utilizadas suelen seguir una estructura regular y pueden ser clasificadas en directas e indirectas, dependiendo de cómo estén interconectados los diferentes elementos de la red. Por otro lado, los algoritmos de encaminamiento también pueden clasificarse en dos categorías: deterministas y adaptativos. Para evaluar estas redes se suelen utilizar medidas tales como la latencia o la productividad de la red. La productividad mide el tráfico que es capaz de aceptar la red por unidad de tiempo. La latencia mide el tiempo que utiliza un paquete para alcanzar su destino. Este tiempo se puede dividir en dos partes. La primera corresponde al tiempo utilizado por el paquete en alcanzar a su destino en ausencia de tráfico en la red. La segunda sería la debida a la congestión de la red creada por el tráfico existente. Uno de los efectos de la congestión es el denominado Head-of-Line blocking, donde el paquete que encabeza una cola se queda bloqueado, por lo que el resto de paquetes de la cola no pueden avanzar, aunque pudieran hacerlo si ellos encabezaran dicha cola. Otros factores a tomar en cuenta son el coste y la tolerancia a fallos. Las prestaciones deben mantenerse conforme aumentamos el tamaño de la red, pero sin un aumento prohibitivo en el coste. Además, el hecho de aumentar el tamaño de la red implica un aumento en el número de elementos de dicha red, aumentando la probabilidad de la aparición de un fallo. Por ello, es vital contar con algún mecanismo de tolerancia a fallos en las redes para los grandes supercomputadores actuales. En otras palabras, es de esperar una buena relación coste-prestaciones con un alto nivel de tolerancia a fallos. Esta tesis tiene dos objetivos principales. El primer objetivo combina las ventajas de las topologías directas e indirectas para crear una nueva familia de topologías con lo mejor de ambas. En concreto, nos centramos en el diseño de una nueva familia de topologías capaz de interconectar una gran cantidad de nodos siendo capaz de obtener muy buenas prestaciones con un bajo coste hardware. La familia de topologías propuesta, que hemos llamado k-ary n-direct s-indirect, tiene una estructura n-dimensional, donde los diferentes k nodos de una dimensión se conectan entre sí mediante una pequeña topología indirecta con s etapas. También diseñaremos un algoritmo de encaminamiento determinista y otro adaptativo para la familia de topologías propuesta. Finalmente, nos centraremos en estudiar la tolerancia a fallos para la familia de topologías propuesta. Para ello se estudiarán los mecanismos de tolerancia a fallos existentes en topologías similares y se diseñará un mecanismo capaz de aprovechar al máximo las características de esta nueva familia. El segundo objetivo consiste en el desarrollo de algoritmos de encaminamiento capaces de evitar el pernicioso efecto Head-of-Line blocking, lo cual puede aumentar rápidamente en sistemas con un gran número de nodos de computación. Para evitar este efecto se diseñarán algoritmos de encaminamiento capaces de clasificar de forma eficiente los paquetes en los diferentes canales virtuales disponibles, evitando así que la aparición de un punto caliente (Hot-Spot) sat
Hui en dia, els clústers de computadors són utilitzats per solucionar grans problemes computacionals. Aquests clústers aprofiten la gran quantitat de nodes de computació per a oferir un alt grau de paral·lelització. Per a connectar tots aquests nodes de computació, s'utilitzen xarxes d'interconnexió d'altes prestacions capaços de manejar de manera eficient el trànsit generat. Aquestes xarxes tenen diferents paràmetres de disseny que defineixen el seu comportament, dels quals podríem destacar dues: la topologia i l'algoritme d'encaminament. La topologia d'una xarxa d'interconnexió ens defineix com es connecten els seus components, mentre que l'algoritme d'encaminament determina la ruta que un paquet ha de prendre des del seu node origen fins al seu node destí. Les topologies més utilitzades solen seguir una estructura regular i poden ser classificades en directes i indirectes, depenent de com estiguen interconnectats els diferents elements de la xarxa. D'altra banda, els algoritmes d'encaminament també poden classificar-se en dues categories: deterministes i adaptatius. Per avaluar estes xarxes es solen utilitzar mesures com ara la latència o la productivitat de la xarxa. La productivitat mesura el trànsit que és capaç d'acceptar la xarxa per unitat de temps. La latència mesura el temps que utilitza un paquet per arribar al seu destí. Aquest temps es pot dividir en dues parts. La primera correspon al temps emprat pel paquet a aconseguir al seu destí en absència de trànsit a la xarxa. La segona part seria la deguda a la congestió de la xarxa creada per el trànsit existent. Un dels efectes de la congestió és l'anomenat Head-of-line blocking, on el paquet que encapçala una cua es queda bloquejat, de manera que la resta de paquets de la cua no poden avançar, encara que poguessen fer-ho si ells encapçalessen la dita cua. Altres factors a tenir en compte són el cost i la tolerància a fallades. Per tant, les prestacions s'han de mantenir d'acord augmentem la mida de la xarxa, però sense un augment prohibitiu en el cost. A més, el fet d'augmentar la mida de la xarxa implica un augment en el número de elements d'aquesta xarxa, de manera que la probabilitat de l'aparició d'una fallada és més gran. Per això, és vital comptar amb algun mecanisme de tolerància a fallades en les xarxes d'interconnexió per als gran supercomputadors actuals. En altres paraules, és d'esperar bona relació cost-prestacions amb una alta tolerància a fallades. Aquesta tesi té dos objectius principals. El primer objectiu combina les avantatges de les topologies directes i indirectes per a crear una nova família de topologies amb el millor dels dos mons. En concret, ens centrem en el disseny de una nova família de topologies capaç d'interconnectar una gran quantitat de nodes sent capaç d'obtenir molt bones prestacions amb un baix cost hardware. La família de topologies proposada, que hem nomenat k-ary n-direct s-indirect, té una estructura n-dimensional, on els diferents k nodes d'una dimensió se connecten entre si mitjançant una petita topologia indirecta amb s etapes. També dissenyarem un algoritme d'encaminament determinista i un altre adaptatiu per a la família de topologies proposta. Finalment, ens centrarem en estudiar la tolerància a fallades per a la família de topologies proposada. Per a això s'estudiaran els mecanismes de tolerància a fallades existents en topologies similars i es dissenyarà un mecanisme capaç d'aprofitar al màxim les característiques d'aquesta nova família. El segon objectiu consisteix en la creació d'algoritmes d'encaminament capaços d'evitar el perniciós efecte Head-of-line blocking que pot créixer ràpidament amb un gran número de nodes de computació. Per a evitar aquest efecte es dissenyaran algoritmes d'encaminament capaços de classificar de forma eficient els paquets en els diferents canals virtuals disponibles, evitant així que l'aparició d'un punt calent (
Peñaranda Cebrián, R. (2017). Improvement of interconnection networks for clusters: direct-indirect hybrid topology and HoL-blocking reduction routing [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/79550
TESIS
Kim, Junhyung. "Analysis of Direct-Soldered Power Module / Heat Sink Thermal Interface for Electric Vehicle Applications." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32071.
Full textMaster of Science
Nguyễn-Thi-Phuong-Hoa. "Foreign direct investment and its contributions to economic growth and poverty reduction in Vietnam (1986 - 2001) /." Frankfurt am Main [u.a.] : Lang, 2004. http://www.gbv.de/dms/zbw/376908386.pdf.
Full textLandon, Colin Donald. "Weighted particle variance reduction of Direct Simulation Monte Carlo for the Bhatnagar-Gross-Krook collision operator." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/61882.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 67-69).
Direct Simulation Monte Carlo (DSMC)-the prevalent stochastic particle method for high-speed rarefied gas flows-simulates the Boltzmann equation using distributions of representative particles. Although very efficient in producing samples of the distribution function, the slow convergence associated with statistical sampling makes DSMC simulation of low-signal situations problematic. In this thesis, we present a control-variate-based approach to obtain a variance-reduced DSMC method that dramatically enhances statistical convergence for lowsignal problems. Here we focus on the Bhatnagar-Gross-Krook (BGK) approximation, which as we show, exhibits special stability properties. The BGK collision operator, an approximation common in a variety of fields involving particle mediated transport, drives the system towards a local equilibrium at a prescribed relaxation rate. Variance reduction is achieved by formulating desired (non-equilibrium) simulation results in terms of the difference between a non-equilibrium and a correlated equilibrium simulation. Subtracting the two simulations results in substantial variance reduction, because the two simulations are correlated. Correlation is achieved using likelihood weights which relate the relative probability of occurrence of an equilibrium particle compared to a non-equilibrium particle. The BGK collision operator lends itself naturally to the development of unbiased, stable weight evaluation rules. Our variance-reduced solutions are compared with good agreement to simple analytical solutions, and to solutions obtained using a variance-reduced BGK based particle method that does not resemble DSMC as strongly. A number of algorithmic options are explored and our final simulation method, (VR)2-BGK-DSMC, emerges as a simple and stable version of DSMC that can efficiently resolve arbitrarily low-signal flows.
by Colin Donald Landon.
S.M.
Lim, Kyungwha. "Reduction of spoilage and pathogenic bacteria on beef products by direct and indirect applications of antimicrobial agents /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p3100061.
Full textDonskoi, Eugene. "The mathematical modelling of direct reduction in iron ore/coal composites including the modelling of coal pyrolysis." Thesis, Queensland University of Technology, 2000.
Find full textLongbottom, Raymond James Materials Science & Engineering Faculty of Science UNSW. "The formation of cementite from hematite and titanomagnetite iron ore and its stability." Awarded by:University of New South Wales. Materials Science and Engineering, 2005. http://handle.unsw.edu.au/1959.4/22023.
Full textVillalva, Gómez Rodrigo. "Structure, Stability and Emissions of Lean Direct Injection Combustion, including a Novel Multi-Point LDI System for NOx Reduction." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384427714.
Full textZhang, Haifeng. "Reduction of methanol crossover in direct methanol fuel cells by an integrated anode structure and composite electrolyte membrane /." View abstract or full-text, 2010. http://library.ust.hk/cgi/db/thesis.pl?CBME%202010%20ZHANG.
Full textRivas, 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 text[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
Duggleby, Andrew Thomas. "Characterization of the Mechanism of Drag Reduction Using a Karhunen-Lo`Eve Analysis on a Direct Numerical Simulation of Turbulent Pipe Flow." Diss., Virginia Tech, 2006. http://hdl.handle.net/10919/28601.
Full textPh. D.
Affadu-Danful, George, Theophilus Neequaye, and Gregory W. Bishop. "Immobilization of Gold Nanoparticles on Nitrided Carbon Fiber Ultramicroelectrodes by Direct Reduction as a Platform for Measuring Electrocatalytic Properties." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/asrf/2018/schedule/13.
Full textBiddinger, Elizabeth Joyce. "Nitrogen-Containing Carbon Nanofibers as Non-Noble Metal Cathode Catalysts in PEM and Direct Methanol Fuel Cells." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274389015.
Full textKempka, Anderson. "Auto-redução do ferro-esponja : uma nova técnica para o aumento de sua qualidade." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/13864.
Full textThe direct reduced iron is obtained by direct reduction process, where iron ore is transformed in metallic iron via chemical reactions involving solid (ore) and gaseous (reductant gases) states. In this process the iron ore does not pass by liquid state like pig iron. This become to direct reduced iron some disadvantages, which decrease its performance in the steelmaking process. It can be mentioned the reduction of metallic yield and the higher consumption of electric energy as the main impacts of its intensive use. The direct reduced iron presents lower amount of total iron (higher amount of impurities) than pig iron and presents iron oxides remained in its structure (lower metallization). To become more competitive, several improvements in the reduction process have been carried out to increase its metallization. However, the highest level of metallization, which has been reached, is 95%. To improve the direct reduced iron quality, the present work evaluates, in an innovative way, using the technique of self reduction. The objective is increase of metallization of the direct reduced iron through its heating. Thermal, chemical and structural characterization was carried out to check the effectiveness of the investigated technique. The research confirms that the direct reduced iron can reach a metallization higher than 98% with a decrease of total carbon amount using the technique presented in this work. An improvement of 4% in the metallization brings savings of 5 to 10% in the electric energy consumption of the electric arc furnaces and a proportional increase of the production in the steelmaking plants.
Wall, Mark John. "Modulation of the swimming motor pattern in Xenopus embryos of GABAâ†B receptors and by direct reduction of potassium currents." Thesis, University of Bristol, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358228.
Full textChala, Zelalem Teklu. "Economic Significance of Selective Export Promotion on Poverty Reduction and Inter-Industry Growth of Ethiopia." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28910.
Full textPh. D.
Waitschat, Arne, Frank Thielecke, Robert M. Behr, and Ulrich Heise. "Active Fluid Borne Noise Reduction for Aviation Hydraulic Pumps." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199594.
Full textAckermann, Douglas Michael Jr. "REDUCTION OF THE ONSET RESPONSE IN HIGH FREQUENCY NERVE BLOCK." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1259791396.
Full textMuwanguzi, Abraham Judah Bumalirivu, Karasev V. Andrey, Byaruhanga K. Joseph, and Jönsson G. Pär. "Characterisation of the Physical and Metallurgical Propertiesof Natural Iron Ore for Iron Production." KTH, Tillämpad processmetallurgi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123058.
Full textQC 20130531
Sustainable Technology Development in the Lake Victoria Region
Thobeka, Adonisi. "Electrochemical characterization of platinum based catalysts for fuel cell applications." Thesis, University of the Western Cape, 2012. http://hdl.handle.net/11394/3812.
Full textFuel cells convert chemical energy from a fuel into electricity through chemical reaction with oxygen. This possesses some challenges like slow oxygen reduction reaction (ORR), overpotential, and methanol fuel cross over in a direct methanol fuel cell (DMFC). These challenges cause inefficiency and use of higher amounts of the expensive platinum catalyst.Several binary catalysts with better ORR activity have been reported. In this study we investigate the best catalyst with better ORR and MOR performances and lower over-potentials for PEMFC and DMFC applications by comparing the in-house catalysts (10%Pt/C, 20%Pt/C,30%Pt15%Ru/C, 40%Pt20%Ru/C, 30%PtCo/C, 20%Pt20%Cu/C and 20%PtSn/C) with the commercial platinum based catalysts (10%Pt/C, 20%Pt/C, 20%Pt10%Ru/C, 20%PtCo/C,20%PtCu/C and 20%PtSn/C) using the cyclic voltammetry and the rotating disk electrode to determine their oxygen reduction reaction and methanol tolerance. HRTEM and XRD techniques were used to determine their particle size, arrangement and the atomic composition. It was observed that the 20%Pt/C in-house catalyst gave the best ORR activity and higher methanol oxidation current peaks compared to others catalysts followed by 20%Pt10%Ru/C commercial catalyst. The 20%PtCo/C commercial, 30%PtCo/C in-house and 20%PtSn/C in-house catalysts were found to be the most methanol tolerant catalysts making them the best catalysts for ORR in DMFC. It was observed that the ORR activity of 20%PtCo/C commercial and 30%PtCo/C inhouse catalysts were enhanced when heat treated at 350 0C. From XRD and HRTEM studies, the particle sizes were between 2.72nm to 5.02nm with little agglomeration but after the heat treatment, the particles were nicely dispersed on the carbon support.
Guney, Murat Efe. "High-performance direct solution of finite element problems on multi-core processors." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34662.
Full textParra, Figueroa Roberto. "Étude expérimentale de la fusion réductrice du Cu2O dans le système Cu2O-FeOx-SiO2." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0118.
Full textTugluk, Ozan. "Direct Numerical Simulation Of Pipe Flow Using A Solenoidal Spectral Method." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614293/index.pdf.
Full textChen, Junbo. "Effect of Defects and Photoexcited Electrons on CO2 Reduction using Supported Single Atom Catalysts." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/1266.
Full textKeskitalo, Björn. "Model studies on the effects of composition differences of direct reduction pellets and an adaptive addition of slag formers for the EAFprocess." Thesis, KTH, Materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-168296.
Full textABU-DAABES, MALYUBA ALI. "SYNTHESIS AND CHARACTERIZATION OF NANO-STRUCTURED CHELATING ADSORBENTS FOR THE DIRECT REMOVAL OF MERCURY VAPOR FROM FLUE-GASES." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1108417592.
Full textOpenshaw, Lizelle. "The Secondary Transfer Effect of Intergroup Contact: An Experimental Study of Direct and Extended Contact." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96904.
Full textENGLISH ABSTRACT : The contact hypothesis (Allport, 1954) provides an established theoretical framework for pursuing positive intergroup relationships (Hewstone & Swart, 2011; Pettigrew & Tropp, 2006) and stipulates certain optimal conditions under which contact reduces prejudice. The secondary transfer effect of contact describes a process whereby attitudes towards outgroups not encountered in the original intergroup encounter might also be improved (Pettigrew, 2009; Pettigrew & Tropp, 2006). A three-wave longitudinal experimental study amongst white South African students at Stellenbosch University (N = 58) was undertaken, using two experimental groups (direct and extended) and a control group. The present study investigated whether direct and extended contact with a black (African) confederate would not only improve attitudes towards black (African) South Africans in general, but also improve attitudes towards Indian South Africans, not involved in the contact situation (i.e., the secondary transfer effect). Findings show that the experimentally manipulated contact reduced intergroup anxiety (from baseline levels measured one week earlier) towards black (African) South Africans. These effects were, however, non-significant, and suggest the present study may have been under-powered. Moreover, the findings showed that experimentally manipulated contact significantly improved outgroup attitudes and outgroup trust (from baseline levels measured one week earlier) towards black (African) South Africans in the direct contact condition, as well as the extended contact condition (outgroup attitudes only). Finally, the present study found significant evidence for the operation of the secondary transfer effect via attitude generalisation. Positive intergroup contact with the black (African) South African confederate predicted a significant change in outgroup attitudes towards black (African) South Africans in general from Time 1 (baseline) to Time 2 (post-task), which in turn predicted more positive attitudes towards Indian South Africans in general at Time 2, controlling for prior quantity and quality of contact with Indian South Africans. The secondary transfer effect was not observed for outgroup trust. The present study contributes to the existing literature on the secondary transfer effect and replicates international findings within the South African context.
AFRIKAANSE OPSOMMING : Die kontak hipotese (Allport, 1954) bied ʼn gevestigde teoretiese raamwerk vir die voortsetting van positiewe intergroep verhoudings (Hewstone & Swart, 2011; Pettigrew & Tropp, 2006) en bepaal sekere optimale toestande waaronder kontak vooroordeel verminder. Die sekondȇre oordrag effek van kontak beskryf ʼn proses waardeur houdings teenoor buitegroepe wat nie gedurende die oorspronklike intergroep kontak teёgekom is nie, ook verbeter word (Pettigrew, 2009; Pettigrew & Tropp, 2006). ʼn Drie-golf longitudinale eksperimentele studie onder wit Suid-Afrikaanse studente verbonde aan die Universiteit van Stellenbosch (N = 58) is onderneem, met behulp van twee eksperimentele groepe (direkte en uitgebreide) en ʼn kontrole groep (N = 16). Die huidige studie het ondersoek of direkte en uitgebreide kontak met ʼn swart (Afrikaan) Suid-Afrikaner nie net houdings teenoor swart (Afrikaan) Suid-Afrikaners in die algemeen verbeter nie, maar ook houdings teenoor Indiёr Suid-Afrikaners, wie nie by die oorspronklike kontak situasie betrokke was nie ook verbeter (d.w.s. die sekondȇre oordrag effek). Resultate toon dat die eksperimenteel gemanipuleerde kontak intergroep angs teenoor swart (Afrikaan) Suid-Afrikaners verminder (vanaf basislyn vlakke gemeet een week tevore). Hierdie effek is egter nie beduidend nie, moontlik omdat die statistiese kragdoeltreffendheid van die studie onvoldoende was. Die resultate toon verder dat eksperimenteel gemanipuleerde kontak buitegroep houdings en buitegroep vertroue (vanaf basislyn vlakke gemeet een week tevore) teenoor swart (Afrikaan) Suid-Afrikaners beduidend verbeter in die direkte kontak groep, sowel as die uitgebreide kontak groep (slegs vir buitegroep houdings). Ten slotte, die huidige studie het beduidende bewyse gevind vir die werking van die sekondȇre oordrag effek via houding veralgemening. Positiewe intergroep kontak met die swart (Afrikaan) Suid-Afrikaner voorspel ʼn beduidende verbetering in die buitegroep houding teenoor swart (Afrikaan) Suid-Afrikaners in die algemeen van Tyd 1 (basislyn) tot Tyd 2 (na die eksperimentele manipulasie), wat op sy beurt meer positiewe houdings teenoor Indiёr Suid-Afrikaners in die algemeen teen Tyd 2 voorspel, nadat daar vir beide kwaliteit en kwantiteit van vorige kontak met Indiёr Suid-Afrikaners beheer is. Die sekondȇre oordrag effek is nie vir buitegroep vertroue waargeneem nie. Die huidige studie dra by tot die bestaande literatuur oor die sekondȇre effek van kontak en ondersteun soortgelyke internasionale bevindinge binne die Suid-Afrikaanse konteks. Stellenbosch University.
Klimm, Nathanael [Verfasser], and Christian [Akademischer Betreuer] Plewnia. "Reduction of excitability in the left inferior frontal gyrus by cathodal transcranial direct current stimulation facilitates emotion recognition / Nathanael Klimm ; Betreuer: Christian Plewnia." Tübingen : Universitätsbibliothek Tübingen, 2019. http://d-nb.info/1197610928/34.
Full textARAUJO, DENILSON RODRIGUES DE. "DEVELOPMENT OF A COMPUTATIONAL TOOL FOR OPTIMIZATION AND VALUE IN USE FORECAST FOR IRON ORE PELLETS THROUGH THE DIRECT REDUCTION: ELECTRIC STEELMAKING ROUTE." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11571@1.
Full textPelo presente trabalho, buscou-se desenvolver uma ferramenta capaz de analisar e otimizar o uso de pelotas de minério de ferro em processos tradicionais de redução direta do tipo forno cuba. A criação de um modelo termoquímico do processo MIDREX foi proposta e elaborada dentro da PUC-Rio, levando-se também em conta alguns aspectos cinéticos relativos à redução dos minérios e à carburização do ferro-esponja, bem como alguns parâmetros operacionais. Este modelo foi subseqüentemente adaptado para interagir com um segundo modelo termoquímico de forno elétrico a arco da RS Consultants, representando assim a cadeia de fabricação de aço líquido primário pela rota redução direta - forno elétrico a arco. Para o gerenciamento computacional do processo de otimização e interação com os dois modelos acima citados, desenvolveu-se, adicionalmente, um terceiro modelo, o qual foi designado neste trabalho como modelo GESTOR. Um máximo uso de ferro-esponja ― e de pelotas, conseqüentemente ― é objetivado sempre que possível, sob determinadas condições operacionais pré-estabelecidas. A avaliação econômica destes processos foi embasada em conceitos de valor de uso. Alguns resultados são apresentados neste trabalho, para demonstrar a efetividade e o poder de análise da ferramenta e espera-se que os profissionais da Samarco possam fazer uso deste instrumento de trabalho, dando o devido suporte à tomada de decisão à comercialização e ao desenvolvimento de produtos existentes ou novos.
The study at issue searched for developing an innovative tool able to effectively analyze and optimize the industrial usage of iron ore pellets undergoing traditional gas-based direct reduction processes. The creation of a thermochemical model for MIDREX process was proposed and carried out by PUC-Rio, taking into account relevant characteristics related to DRI carburization and reduction kinetics, as well as some important operating parameters. Subsequently, this model was adapted in order to interact with a second thermo-chemical model owned by RS Consultants and able to represent an electric arc furnace operation. In this sense, it has been possible to represent thereby the iron and steelmaking route based on direct reduction and electric arc furnace. For the computational management of the optimization methodology and interaction involving the two models above-mentioned, a third model was developed and referred to as GESTOR model. It was built to maximize the DRI usage ¯ and pellets utilization, consequently ¯ respecting certain operating conditions previously established. Economic assessments shall be made premised upon value in use concepts. Some results are shown in this study, based on a hypothetical scenario, aiming at proving the effectiveness of this tool. Its adoption by Samarco´s experts is expected as an important supportive methodology to help them to make decisions properly concerning both marketing strategies and product development activities.
FALERO, EDELINK EFRAIN TINOCO. "DEVELOPMENT OF A TECHNIQUE TO PERMIT THE USE OF IRON ORES BEARING HIGH PHOSPHOR CONTENT AIMING AT COMPETITIVENESS FOR THE DIRECT REDUCTION MARKET." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=19251@1.
Full textPROGRAMA DE SUPORTE À PÓS-GRADUAÇÃO DE INSTS. DE ENSINO
As pelotas de minério de ferro têm suas propriedades fortemente dependentes da natureza das fases escorificadas que se formam durante o processo de queima. Neste trabalho são apresentados os resultados de uma das pesquisas que compõem o projeto cooperativo entre a Samarco e o Grupo de Siderurgia do DEMa / PUC-Rio, envolvendo a possibilidade de utilização de minérios de ferro portadores de fósforo (pellet feed), na produção de pelotas para redução direta. Com este objetivo foram geradas amostras de escórias sintéticas de mesma composição que as das pelotas RD comerciais, as quais foram submetidas a condições experimentais análogas as do processo industrial. Inicialmente a ciclos térmicos em forno tipo pot-grate e, posteriormente, em escala laboratorial, usando forno de mufla, seguido de etapas de resfriamento em velocidades distintas. Foi possível então constatar que velocidades mais altas de resfriamento, aplicadas na etapa final dos ciclos térmicos, produziam escórias sintéticas sensivelmente amorfas, o que levou a conclusão que as fases escorificadas das pelotas RD também se apresentariam como estruturas não cristalinas. Finalmente, por meio de teste especificamente desenvolvido para a análise seletiva de fósforo em fases oxídicas, conseguiu-se obter uma maior eficiencia na mensuração deste elemento quando dissolvido em escórias amorfas, o que viabilizou a medida das quantidades de fósforo que efetivamente migraram para as mesmas, quando se submetiam as amostras de pellet feed a diferentes temperaturas, variados tempos de residencia e distintas basicidades. Por fim, foi possivel concluir ser o incremento de basicidade do pellet feed um fator de significativa melhoria para o transporte e a dissolução do fósforo pelas escórias, em particular quando submetidos a temperaturas superiores a 900 graus Celsius.
Iron ore pellets have their properties strongly dependent on the nature of the phases present in the slags formed during pelletization. In this work are presented the first results of a research program involving the utilization of phosphorous bearing iron ores in the production of DR pellets (Direct Reduction pellets). Aiming at this, synthetic slags, produced with same composition of the gangue of a commercial DR pellet, were submitted to operational conditions similar to those of the industrial pelletizing process, but performed in a pot-grate reactor and in a laboratory furnace. The obtained slags samples were cooled at different rates, permitting to observe that at high cooling rates the slags obtained were amorphous, suggesting the occurrence of a similar amorphous structure for the slags present in the DR pellets. Finally, tests developed for a selective analysis of phosphorous in oxide phases, showed better efficiency when applied to amorphous slags than in crystalline ones. Further, the behavior of the phosphor dissolution in the obtained slags during the heating of pellet feed samples was evaluated. In this phase different temperatures, resident times and basicities were tested using a laboratory furnace. The results indicated improvements in the phosphor dissolution with the basicity increase when temperatures above 900 Celsius degrees were applied.
Osano, Philip. "Direct payments to promote biodiversity conservation and the implications for poverty reduction among pastoral communities in East African arid and semi-arid lands." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=119494.
Full textLes payements pour les services d'écosystème (PSE) sont largement utilisés pour la conservation de la biodiversité et le management des services environnementaux. Particulièrement en Afrique, les PSE sont supposés générer des revenus complémentaires pour la réduction de la pauvreté et l'amélioration des moyens de subsistance dans les zones rurales. Cependant, il y a très peu de PSE dans les zones arides et semi-arides (ZASA) qui impliquent les communautés pastorales et semi-nomades. Il y a peu d'évidences empiriques de l'impact des PSE sur la pauvreté. Cette thèse évalue les changements en biodiversité, les services environnementaux, la population humaine et la variation climatique dans les ZASA au Kenya. L'étude examine aussi les implications potentielles et réelles des PSE sur la pauvreté et les adaptations au changement climatique fondées sur les écosystèmes de deux communautés pastorales Maasai vivant à proximité des zones protégées de la faune sauvage dans le sud du Kenya. L'étude génère l'évidence des effets positifs des PSE sur les moyens de subsistance des familles participantes, particulièrement pendant une période d'extrême sécheresse quand les PSE servent comme un moyen de sécurité contre la mortalité élevée du bétail et la perte de revenus de l'élevage. Les PSE sont comme une source précieuse de diversification des revenus avec un effet de réduction de l'inégalité des revenus. Malgré ses aspects positifs, il est nécessaire d'évaluer et de contrôler les conséquences négatives potentielles de l'impact des PSE les non-participants et les familles sans terre. Les inquiétudes se posent sur les implications d'équité, et le manque de financement durable des programmes.
Coussement, Axel. "Direct numerical simulation and reduced chemical schemes for combustion of perfect and real gases." Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209765.
Full textDe plus, ces conditions ont été étendues au cas des gaz réels et une nouvelle définition du facteur de relaxation pour la pression a été proposée. Ce nouveau facteur de relaxation permet de supprimer les déformations observées en sortie pour des écoulements transcritiques.
Les résultats obtenus avec le code YWC ont ensuite été utilisés dans la seconde partie de la thèse pour développer une nouvelle méthode de tabulation basée sur l'analyse en composantes principales. Par rapport aux méthodes existante telles que FPI ou SLFM, la technique proposée, permet une identification automatique des variables à transporter et n'est, de plus, pas lié à un régime de combustion spécifique. Cette technique a permis d'effectuer des calculs d'interaction flamme-vortex en ne transportant que 5 espèces à la place des 9 requises pour le calcul en chimie détaillée complète, sans pour autant perdre en précision.
Finalement, dans le but de réduire encore le nombre d'espèces transportées, les techniques T-BAKED et HT-BAKED PCA ont été introduites. En utilisant une pondération des points sous-représentés, ces deux techniques permettent d'augmenter la précision de l'analyse par composantes principales dans le cadre des phénomènes de combustion.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
SANTOS, MONIQUE C. L. "Oxidação eletroquímica do metanol em eletrólito alcalino por intermédio de eletrocatalisadores PtRuIn/C preparados pelo método de redução por borohidreto de sódio." reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28042.
Full textMade available in DSpace on 2017-11-22T17:28:56Z (GMT). No. of bitstreams: 0
Neste trabalho os diferentes sistemas eletrocatalíticos PtIn/C, PtRu/C, PtRuIn/C e suas diferentes proporções mássicas foram sintetizados pelo método de redução por Borohidreto de Sódio, a fim de serem utilizados como ânodo na célula a combustível alcalina de metanol direto (DMFC). Os materiais obtidos foram caracterizados pelas técnicas de EDX, DRX e MET. O método de redução aplicado na síntese se mostrou efetivo, uma vez que as partículas apresentaram boa dispersão no suporte de carbono Vulcan XC72, de acordo com as analises de EDX e MET. Os resultados obtidos por DRX evidenciaram em todos os difratogramas apresentados a estrutura CFC da platina e um relativo deslocamento do pico equivalente ao plano (220) para valores maiores e menores que 2θ. O tamanho médio do cristalito e os parâmetros de rede calculados indicaram a inserção de átomos de Índio e Rutênio à estrutura da Platina, supondo a formação de ligas. A oxidação eletroquímica do metanol foi estudada por voltametria cíclica, cronoamperometria e curvas de polarização. Os experimentos eletroquímicos demonstraram que nos eletrocatalisadores binários com maior composição de Índio e Rutênio a eficiência catalítica frente a oxidação do combustível foi melhor e para os ternários, o eletrocatalisador que possuía maior composição de Rutênio se mostrou mais eficiente. Nos experimentos práticos em células a combustível, as curvas de polarização mostraram divergências de resultados com os obtidos por voltametria cíclica e cronoamperometria, justificadas por problemas de prensagem e descolamento de MEA\'s em sistemas que apresentaram maior quantidade de cocatalisador como Índio e Rutênio.
Dissertação (Mestrado em Tecnologia Nuclear)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
Moosaie, Amin [Verfasser], Michael [Akademischer Betreuer] Manhart, Bernd [Akademischer Betreuer] Simeon, and Eric Stefan G. [Akademischer Betreuer] Shaqfeh. "Direct Numerical Simulation of Turbulent Drag Reduction by Rigid Fiber Additives / Amin Moosaie. Gutachter: Michael Manhart ; Bernd Simeon ; Eric Stefan G. Shaqfeh. Betreuer: Michael Manhart." München : Universitätsbibliothek der TU München, 2011. http://d-nb.info/1015804683/34.
Full textZHANG, HAO. "ELECTROCHEMICAL DEGRADATION OF 4-CHLOROPHENOL." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1154119633.
Full textCarey, Daniel Jeffrey. "Statistical modelling and reduction of multiple access interference power in wideband DS-CDMA and MC-CDMA communications systems." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16342/1/Daniel_Carey_Thesis.pdf.
Full textCarey, Daniel Jeffrey. "Statistical modelling and reduction of multiple access interference power in wideband DS-CDMA and MC-CDMA communications systems." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16342/.
Full text