Les réglementations sur les NOx émis par les avions sont sévères. Les techniques les réduisant ont des inconvénients. Pour les supprimer, deux pistes sont explorées. La première modifie l'architecture des chambres de combustion et les stabilise par une cavité. La seconde dope le kérosène au ralenti.Peu d'information est disponible sur les mécanismes de stabilisation et sur la structure de flamme des Trapped Vortex Combustor. Pour y remédier, un TVC est construit. L'étude de l'écoulement à froid ainsi que l'étude temporellement résolue de la flamme, mettent en avant les éléments stabilisateurs et déstabilisateurs. L'impact de la structure de flamme sur les émissions est évalué.La seconde partie porte sur l'effet de l'ajout d'hydrogène et de gaz de reformeur dans une chambre conventionnelle. Malgré une légère augmentation des émissions de NOx, l'ajout de composés hydrogénés réduit fortement les émissions de CO, augmente la stabilité et réduit la limite d'extinction pauvre.

Homogeneously charged spark ignition (SI) engines are unable to stabilise the combustion in ultra lean mixtures, therefore they operate with a near stoichiometric air-fuel ratio (AFR) at all load points. This produces high engine out NOx and CO emissions with a compromise on fuel consumption. Moreover, stoichiometric operation is needed for effective operation of a three way catalyst, which is not adequate to meet future fuel consumption targets. (For complete abstract open document)

Le travail de la thèse s’articule sur le développement d’un nouveau type de capteurs de gaz à base des matériaux semi-conducteurs III-Nitrure (Les nitrures de gallium). Ces matériaux présentent de nombreux avantages qui pourraient être utilisées pour concevoir des capteurs NOx sensibles et sélectifs pour le contrôle des pollutions émises par la ligne d’échappement Diesel. Afin de limiter et déduire les gaz polluants émis par les moteurs à explosion en générale et les moteurs Diesel en particuliers (NO, NO2, NH3, CO, …), différentes normes européennes ont été établies. Pour respecter ces normes, plusieurs modifications sur les moteurs et les lignes d’échappement des véhicules ont été effectuées (filtres à particules, catalyseurs, capteurs NOx, …). Les capteurs NOx utilisés actuellement sont à base d’électrolyte solide. Ils sont basés dans leur fonctionnement sur la mesure de la concentration d’oxygène présente dans le gaz d’échappement qui permet de son tour l’estimation de la concentration totale des gaz NOx (mesure indirecte). Ces capteurs ne détectent pas le NH3 à la sortie de la ligne d’échappement, et ne donnent pas une information précise sur le rapport entre NO et NO2 (manque de sélectivité) qui est un facteur important pour le bon fonctionnement de catalyseur sélectif SCR (amélioration de rendement) ; d’où la nécessité d’un capteur de gaz plus performant et en particulier sélectif afin d’améliorer les systèmes de contrôle, de post-traitement et de diagnostic. Notre approche consiste à utiliser un transistor HEMT (High Electron Mobility Transistor) à gaz bidimensionnel d’électrons à base de nitrure de Gallium avec l’association d’une couche fonctionnelle à la place de la grille. L’interaction des molécules de gaz avec cette couche fonctionnelle donne une signature (variation de signal de sortie) spécifique pour chaque type de gaz qui aide à l’amélioration de la sélectivité. Le projet contient deux parties : l’optimisation de la structure choisie et l’optimisation de la couche fonctionnelle afin d’obtenir une détection sélective entre les différents gaz polluants. Cette technologie est intéressante pour développer des capteurs de gaz grâce aux possibilités de détecter des faibles variations de tensions et aux possibilités de fonctionnement dans des environnements sévères. La thèse de doctorat s’inscrit dans le cadre de l’OpenLab materials and processes en collaboration entre le laboratoire Georgia-Tech lorraine et l’entreprise Peugeot-Citroën PSA / The work of the thesis focuses on the development of a new type of gas sensors based III-Nitride semiconductor materials (gallium nitrides). These materials have many advantages that could be used to develop sensitive and selective NOx sensors for the control of pollution emitted by diesel exhaust line. To limit the polluting gases emitted by internal combustion engines in general and diesel in particular (NO, NO2, NH3, CO, ...), different European standards have been established. To meet these standards, anti-pollution systems (consisting of particle filters, catalysts, NOx sensors, ... etc) are used. NOx sensors currently used in automobiles are based on a solid electrolyte. Their operation is based on the measurement of the oxygen concentration. This enables an estimate of the total concentration of NOx gas (indirect measurement) after filtering NOx from O2 and decomposing NOx into O2. These sensors do not detect NH3 at the outlet of the exhaust line, and do not give accurate information on the relationship between NO and NO2 (lack of selectivity) which is important factor for an optimal functioning of selective catalyst (SCR performance improvement). Hence there exists a need for a more efficient and selective in particular gas sensor to improve the control systems, post-treatment and diagnosis. Our approach is to use a HEMT (High Electron Mobility Transistor) transistor based on gallium nitride with a combination of a functional layer instead of the gate. The interaction of the gas molecules with the functional layer gives a signature (output signal variation) specific for each type of gas that helps to improve the selectivity. The project contains two parts: the optimization of the chosen structure and the optimization of the functional layer in order to achieve selective detection between various gaseous pollutants. This technology is interesting for development of gas sensors through the possibility of detection low voltage variations and the possibility of operating in harsh environments. The thesis is part of OpenLab "Materials and Processes" in a collaboration between Georgia Tech-CNRS laboratory and the PSA Peugeot-Citroen Group

No description available.

Philosophiae Doctor - PhD / Nitric Oxide (NO) influences a wide range of physiological processes in plants including growth and development, responses to abiotic and biotic stress and pathogen responses. NO binds to the heme group of the mammalian soluble guanylyl cyclase, which activates the enzyme to convert guanosine 5’ triphosphate (GTP) to a second messenger guanosine 3’, 5’ cyclic monophosphate (cGMP). Cyclic GMP further activates other signalling cascades including the regulation of protein kinases, ion gated channels and phosphodiesterases. In plants, a few GCs have been identified and these include AtGC1, AtBRI1, AtWAKL10, and AtPSKR1, however, a GC that contains a heme binding motif that senses NO has yet to be identified. In order to identify such molecules, a search motif based on conserved HNOX domains and the conserved and functionally assigned amino acid residues in the catalytic centres of annotated GCs was designed and used to search the Arabidopsis thaliana proteome. Several candidate molecules were identified including a flavin-containing monooxygenase (FMO)-like protein and the At5g57690 which is currently annotated as a diacylglycerol kinase. FMOs found in bacteria, yeast, and animals are the most important monooxygenases since they are involved in xenobiotic metabolism and variability in drug response. FMOs in plants are implicated in catalysing specific steps in auxin biosynthesis,metabolism of glucosinolates and pathogen defense mechanisms. The human diacylglycerol kinase acts as a lipid kinase that mediates a wide range of biological processes which include cell proliferation, differentiation and turmogenesis. In prokaryotes, the structure of Escherichia coli lipid kinase has been solved however, its function has not yet been demonstrated. So far, the occurrence of the diacylglycerol kinases in plants has not yet been reported, and their structure and function also remain elusive. The domain architecture of the 2 molecules (AtNOGC1 and At5g57690) identified by the HNOX-based search strategy revealed that these molecules contain a GC and a heme-binding motif that is conserved among all known heme-binding proteins.In this study, the role of AtNOGC1, a novel NO binding protein in higher plants was investigated and the results showed that this molecule contains an NO-dependant active GC domain. The sequence was first analysed and the location of the HNOX and the GC motifs highlighted. The protein was then recombinatly expressed as a His-SUMO fusion protein and the purification optimised by a second step of ion exchange chromatography. Electrochemical techniques such as cyclic voltammetry and square wave voltammetry were used to demonstrate the binding of NO and O2 to the AtNOGC1. Electrochemical data revealed that AtNOGC1 has a lower affinity for O2 and a higher affinity for NO, an important signalling molecule in plants.The presence of the GC activity in AtNOGC1 was investigated by conducting GC activity assays in vitro in the presence or absence of NO. The GC activity assays demonstrated that AtNOGC1 can synthesize cGMP from GTP in vitro. It was also noted that NO was required for the maximum activation of AtNOGC1 catalytic activity. NO-activated catalysis resulted in a >2 fold excess of cGMP production compared to an NO-independent GC activity assay. The effect of calcium in regulating the GC activity was also investigated and an increase in cGMP levels was observed however, this was just a preliminary finding that requires further experimentation.3 Homology models for both the FMO-like (AtNOGC1) and the diacylglycerol kinase(At5g57690) were built using Modeller program, and important amino acid residues underlying the heme-binding and GC motifs were identified. Residues corresponding to the motifs, which give signature to AtNOGC1 as an FMO, were also noted. In addition,computational functional prediction also suggested the role of AtNOGC1 in a number of processes which include ion binding and functioning as an FMO.Taken together, these findings suggest that AtNOGC1 is a novel Arabidopsis thaliana hemebinding protein that senses NO with higher affinity than for O2. Though AtNOGC1 is currently annotated as a FMO-like protein, it contains a NO-sensitive GC activity and shares limited sequence similarities with mammalian sGC and the recently identified HNOX domains. Homology modelling strongly suggests that AtNOGC1 and At5g57690 belong to the families of FMOs and diacylglycerol kinases respectively. The domain organisation of AtNOGC1 suggests that more of its functions still remain to be identified. The cloning and characterisation of the At5g57690 gene will provide possible means for further experimentation as well as affording more insights into the exact functions of lipid kinases in plants.

O presente trabalho trata da modelagem de combustão em um queimador industrial de gás natural utilizando cadeias de reatores químicos idealizados. A partir de simulações de CFD e dados experimentais do ensaio denominado BERL 300 kW, sucessivas cadeias de reatores são propostas, baseando-se em premissas sobre as condições de temperatura e fluxo de massa entre as diversas regiões do escoamento reativo. O objetivo é obter uma cadeia de reatores que reproduza as emissões de NOx do ensaio. O erro relativo das emissões é de 98,23% na primeira cadeia, de 82,30% na segunda cadeia e de 1,54% na terceira cadeia. A partir da terceira cadeia de reatores proposta, considerada representativa do ensaio, realiza-se uma análise de sensibilidade e um estudo paramétrico, para avaliar a sensibilidade do modelo aos ajustes de segmentação de correntes e a capacidade de reproduzir os dados experimentais de emissão em condições de pré-aquecimento do ar de combustão e em operação fora do ponto de projeto. O modelo produz resultados satisfatórios para os casos de pré-aquecimento do ar até 110°C e para potências térmicas até 33% superiores ao ponto de projeto, não oferecendo bons resultados para as demais condições de operação. / This work shows the development and application of chemical reactor networks (CRN) to the modeling of a natural gas burner. The CRN development is based on experimental and CFD simulation results of the BERL 300 kW test. The CRN element arrangement, reactor volumes and flow splits are adjusted based on the best agreement with characteristic temperatures of the reactive flow, aiming to reproduce the experimental NOx emissions data. The relative error in the emissions predictions are 98,23% for the first CRN proposed, 82,30% for the second CRN and 1,54% for the third one. A sensitivity analysis and a parametric study of the third CRN are carried out to evaluate its sensitivity to the flow splits adjustments and its ability to predict emission with air preheat and turndown operation. The NOx emissions predicted by CRN are in good agreement until 110ºC preheating and for a turndown ratio of 1,33.

Submitted by Elizabete Silva (elizabete.silva@ufes.br) on 2015-11-23T19:08:09Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) INFLUÊNCIA DOS COMPOSTOS ORGÂNICOS VOLÁTEIS NO POTENCIAL DE FORMAÇÃO DO OZÔNIO TROPOSFÉRICO NA GRANDE VITÓRIA-ES.pdf: 3636611 bytes, checksum: 18bc0a9ce6ff16e16830e30e01febabc (MD5) / Approved for entry into archive by Morgana Andrade (morgana.andrade@ufes.br) on 2016-01-05T10:15:50Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) INFLUÊNCIA DOS COMPOSTOS ORGÂNICOS VOLÁTEIS NO POTENCIAL DE FORMAÇÃO DO OZÔNIO TROPOSFÉRICO NA GRANDE VITÓRIA-ES.pdf: 3636611 bytes, checksum: 18bc0a9ce6ff16e16830e30e01febabc (MD5) / Made available in DSpace on 2016-01-05T10:15:50Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) INFLUÊNCIA DOS COMPOSTOS ORGÂNICOS VOLÁTEIS NO POTENCIAL DE FORMAÇÃO DO OZÔNIO TROPOSFÉRICO NA GRANDE VITÓRIA-ES.pdf: 3636611 bytes, checksum: 18bc0a9ce6ff16e16830e30e01febabc (MD5) Previous issue date: 2014 / CNPQ / Neste estudo, foi avaliado o potencial de formação do ozônio troposférico (PFO) a partir da influência dos compostos orgânicos voláteis (COV) presentes na atmosfera da Região Metropolitana da Grande Vitória (RMGV) entre os períodos de 05/02/2013 a 05/04/2013 e entre 16/05/2013 a 21/06/2013. Cada espécie de COV reativo possui um determinado potencial na formação do ozônio, por isso, a importância no conhecimento dessas espécies presentes na atmosfera local é de suma importância na proposição de medidas de controle da poluição do ar. Por meio de amostradores passivos um total de 96 amostras foram coletadas em três estações da rede de monitoramento da qualidade do ar (RAMQAr) da RMGV, localizadas nos bairros Laranjeiras, Enseada do Suá e Ibes. A caracterização qualitativa e quantitativa dos COV possibilitou quantificar o PFO da região através do método de escala de reatividade máxima por incremento (MIR) proposta por Carter (1994). Os resultados indicaram que o grupo de COV predominante na RMGV é dos ácidos orgânicos, seguido pelos álcoois e aromáticos substituídos. Entre os COV com maior potencial de formação do ozônio, os compostos undecano, tolueno, etilbenzeno e o,m,p-xileno são os de maior abundância na RMGV, apresentando médias, respectivamente, de 0,855 μg m-3, 0,365 μg m-3 , 0,259 μg m-3 e 0,289 μg m-3 no período entre 16/05/2013 a 21/06/2013. Os resultados ainda indicaram que os BTEX, grupo constituído por benzeno, tolueno, etilbenzeno e o,m,p-xilenos, encontraram-se abaixo dos valores considerados prejudiciais a saúde da população na RMGV. O PFO na RMGV calculado a partir de todos os compostos do grupo COV precursores foi de 22,55 μg m-3 para o período de 05/02/2013 a 05/04/2013 e de 32,11 μg m-3 para o período de 16/05/2013 a 21/06/2013, sendo que, os compostos, tolueno e o-xileno foram responsáveis por aproximadamente 37% de todo o PFO produzido a partir do grupo COV precursores. Uma avaliação revelou que o valor geral da razão COV/NOx para a RMGV foi de aproximadamente 1,71, indicando que a região apresenta uma condição COV-limitante na produção do ozônio. Portanto, a adoção de medidas apenas para remoção de NOx da atmosfera da RMGV poderá favorecer as reações entre o OH e os COV, formando radicais que possibilitam regenerar o NO2 e favorecendo o aumento da taxa líquida de produção do ozônio na região. / In the present study, the ozone forming potential (OFP) from volatile organic compounds (VOCs) in the atmosphere of Metropolitan Region of Grande Vitória (RMGV) has been studied on the periods between 02/05/2013 to 04/05/2013 and 05/16/2013 to 06/21/2013. Each species of VOC has a particular reactivity on ozone forming potential, so the knowledge of these species in the local atmosphere is of great importance in proposing measures to control of air pollution. Passive samplers were installed at three of air quality monitoring stations (RAMQAr) of RMGV, and a total of 96 samplings were collected between the two sampling periods. By the characterization and quantification of VOC was possible to quantify the OFP applying the scale of maximum incremental reactivity (MIR) proposed by Carter (1994). The results indicated that the predominant group of VOCs in the RMGV is the organic acids, followed by alcohols and substituted aromatics. Among the VOCs with the greatest OFP, the undecane, toluene , ethylbenzene and m, p-xylene compounds are the most abundant in RMGV, presenting the means of 0,855 μg m-3, 0,365 μg m-3 , 0,259 μg m-3 and 0,289 μg m-3, respectively, on the period 05/16/2013 to 06/21/2013. The results also indicated that the BTEX group consisting of benzene, toluene, ethylbenzene and m,p-xylenes are below of the limits considered harmful to the health of the population in RMGV . The ozone forming potential in RMGV calculated from all the precursors VOC group was 22.55 μg m-3 in summer period and 32.11 μg m-3 in the winter period. The toluene and o-xylene compounds are responsible for approximately 37 % of all OFP produced from precursors VOC group. The assessment of the VOC/NOx ratio revealed that the overall value of that ratio in RMGV is approximately 1.71, indicating that the region has a VOC-limiting condition for the production of ozone. Therefore, the adoption of measures only to remove NOx from the atmosphere of RMGV could favor reactions between OH and VOC, forming radicals that enable regenerate NO2 increasing the net rate of ozone production in the region.

Atualmente, vários pesquisadores da arquitetura, investiga as possibilidades de absorção da tecnologia digital na arquitetura. Dentre as diversas posturas, destaca a do grupo de arquitetos holandeses Nox cujo método de concepção que utiliza técnicas digitais e analógicas, assim como acolhe o conhecimento de outras disciplinas e enfatizam a topologia como um dos eixos norteador, a obra do grupo indica as questões para o debate. Dialogando com outros autores, este tema reflete sobre as modificações pelas quais passa a arquitetura. / Nowadays, different groups of architects search for the possibilities of digital Technology contribution to architecture. Among the various stances, this paper particularly highlights the Dutch architects group called Nox, which develops a design method that uses both digital and analogical techniques, as well as incorporates knowledge from other disciplines. The Dutch group’s work serves as a guideline, as it indicates the subjects to be examined. Also based on the studies of other authors, the present research analyses the modifications contemporary architecture is going through, such as matters related to form, design method and conceiving of space, time and reality.

Atualmente, vários pesquisadores da arquitetura, investiga as possibilidades de absorção da tecnologia digital na arquitetura. Dentre as diversas posturas, destaca a do grupo de arquitetos holandeses Nox cujo método de concepção que utiliza técnicas digitais e analógicas, assim como acolhe o conhecimento de outras disciplinas e enfatizam a topologia como um dos eixos norteador, a obra do grupo indica as questões para o debate. Dialogando com outros autores, este tema reflete sobre as modificações pelas quais passa a arquitetura. / Nowadays, different groups of architects search for the possibilities of digital Technology contribution to architecture. Among the various stances, this paper particularly highlights the Dutch architects group called Nox, which develops a design method that uses both digital and analogical techniques, as well as incorporates knowledge from other disciplines. The Dutch group’s work serves as a guideline, as it indicates the subjects to be examined. Also based on the studies of other authors, the present research analyses the modifications contemporary architecture is going through, such as matters related to form, design method and conceiving of space, time and reality.

Made available in DSpace on 2016-06-02T19:56:45Z (GMT). No. of bitstreams: 1 3936.pdf: 2010584 bytes, checksum: 3be708f515e15835c7915065004f5f86 (MD5) Previous issue date: 2011-10-27 / The minimization of emissions of nitrogen oxides (NOx) is a subject of great interest because they cause serious environmental problems affecting human health, flora and fauna. To break down the NOx catalytic reduction of these compounds to N2 has acquired great importance and may occur in the absence or presence of a reducing agent. The selective catalytic reduction using ammonia as a reducing agent (NH3-SCR) has been shown to be one of the most attractive, being used worldwide to control NOx emissions by industries due to its high efficiency, selectivity and low cost. To obtain more efficient catalysts for this reaction, several studies have been developed. In this context, the objective of this work is to prepare, to wet impregnation, catalysts based on vanadium, molybdenum and iron supported on commercial TiO2 and lamellar titanates (TL) with high (A-TL) or low-sodium (B-TL), and apply them to the reduction of NO with NH3.It was also studied the effect of calcination temperature in titanates with low sodium content. Results of XRD and adsorption of N2 measurements confirmed the formation of TL mesoporous structure and high specific surface area. After the addition of metal to TiO2 and TL, it was observed a significant decrease in the values of specific surface areas, attributed to the filling of pores by metal oxides. The RTP-H2 showed lower reducibility of metals supported on the lamellar titanates and commercial TiO2 support. The catalysts supported TL with high sodium content showed lower catalytic activity compared to commercial catalysts . However, the catalysts supported on titanates with low sodium content showed promising results in the conversion of NO to N2. The catalysts Fe2O3/TiO2 Fe2O3/B-TL showed loss of activity in the presence of SO2, which partially regenerates in the absence of the compound. In the presence of water, both catalysts showed a decline in the conversion, With the removal of H2O the Fe2O3/TiO2 showed partial regeneration, while the Fe2O3/B-TL suffered irreversible deactivation. / A minimização das emissões de óxidos de nitrogênio (NOx) é assunto de alto interesse pois causam graves problemas ambientais afetando a saúde humana, à flora e à fauna. Para abater os NOx, a redução catalítica desses compostos a N2 vem adquirindo grande relevância, podendo ocorrer na ausência ou presença de um agente redutor. A redução catalítica seletiva utilizando amônia como agente redutor (RCS-NH3) tem-se mostrado um dos processos mais atrativos, sendo mundialmente aplicado no controle de emissão do NOx pelas indústrias, devido a sua alta eficiência, seletividade e baixo custo. Para a obtenção de catalisadores mais eficientes para essa reação, diversos estudos tem sido desenvolvidos. Nesse contexto, o objetivo deste trabalho é preparar, via impregnação úmida, catalisadores à base de vanádio, molibdênio e ferro suportados em TiO2 comercial e titanatos lamelares (TL) com alto (A-TL) ou (B-TL) baixo teor de sódio, e aplicá-los na redução de NO com NH3. Foi verificado estudado também o efeito da temperatura de calcinação nos titanatos com baixo teor de sódio. Resultados de DRX e medidas de adsorção de N2 confirmaram a formação de TL de estrutura mesoporosa e de alta área superficial específica. Após a adição dos metais aos suportes TiO2 e TL, foi observada uma queda significativa nos valores das áreas superficiais específicas, atribuída ao preenchimento dos poros pelos óxidos metálicos. O RTP-H2 indicou menor redutibilidade dos metais suportados nos titanatos lamelares frente ao suporte TiO2 comercial. Os catalisadores suportados em TL com alto teor de sódio apresentaram atividade catalítica inferior quando comparados aos catalisadores suportados em TiO2 comercial. No entanto, os catalisadores suportados nos titanatos com baixo teor de sódio apresentaram resultados promissores na conversão do NO a N2. Os catalisadores Fe2O3/TiO2 e Fe2O3/B-TL registraram queda parcial na atividade quando na presença do SO2, que se regenera parcialmente na ausência do composto. Na presença de água, ambos catalisadores apresentaram queda na conversão, sendo que, na retirada deste composto, o Fe2O3/TiO2 apresentou parcial regeneração, ao passo que, o Fe2O3/B-TL, sofreu desativação irreversível.