No description available.

Land application of wastes has become increasingly popular, to promote nutrient recycling and environmental protection, with soil functioning as a partial barrier between wastes and groundwater. Dairy shed effluent (DSE), may contain a wide variety of pathogenic micro-organisms, including bacteria (e.g. Salmonella paratyphyi, Escherichia coli. and Campylobacter), protozoa and viruses. Groundwater pathogen contamination resulting from land-applied DSE is drawing more attention with the intensified development of the dairy farm industry in New Zealand. The purpose of this research was to investigate the fate and transport of bacterial indicator-faecal coliform (FC) from land-applied DSE under different irrigation practices via field lysimeter studies, using two water irrigation methods (flood and sprinkler) with contrasting application rates, through the 2005-2006 irrigation season. It was aimed at better understanding, quantifying and modelling of the processes that govern the removal of microbes in intact soil columns, bridging the gap between previous theoretical research and general farm practices, specifically for Templeton soil. This study involved different approaches (leaching experiments, infiltrometer measurements and a dye infiltration study) to understand the processes of transient water flow and bacterial transport; and to extrapolate the relationships between bacterial transport and soil properties (like soil structure, texture), and soil physical status (soil water potential ψ and volumetric water content θ). Factors controlling FC transport are discussed. A contaminant transport model, HYDRUS-1D, was applied to simulate microbial transport through soil on the basis of measured datasets. This study was carried out at Lincoln University’s Centre for Soil and Environmental Quality (CSEQ) lysimeter site. Six lysimeters were employed in two trials. Each trial involved application of DSE, followed by a water irrigation sequence applied in a flux-controlled method. The soil columns were taken from the site of the new Lincoln University Dairy Farm, Lincoln, Canterbury. The soil type is Templeton fine sandy loam (Udic-Ustochrept, coarse loamy, mixed, mesic). Vertical profiles (at four depths) of θ and ψ were measured during leaching experiments. The leaching experiments directly measured concentrations of chemical tracer (Br⁻ or Cl⁻) and FC in drainage. Results showed that bacteria could readily penetrate through 700 mm deep soil columns, when facilitated by water flow. In the first (summer) trial, FC in leachate as high as 1.4×10⁶ cfu 100 mL⁻¹ (similar to the DSE concentration), was detected in one lysimeter that had a higher clay content in the topsoil, immediately after DSE application, and before any water irrigation. This indicates that DSE flowed through preferential flow paths without significant treatment or reduction in concentrations. The highest post-irrigation concentration was 3.4×10³ cfu 100 mL⁻¹ under flood irrigation. Flood irrigation resulted in more bacteria and Br⁻ leaching than spray irrigation. In both trials (summer and autumn) results showed significant differences between irrigation treatments in lysimeters sharing similar drainage class (moderate or moderately rapid). Leaching bacterial concentration was positively correlated with both θ and ψ, and sometimes drainage rate. Greater bacterial leaching was found in the one lysimeter with rapid whole-column effective hydraulic conductivity, Keff, for both flood and spray treatments. Occasionally, the effect of Keff on water movement and bacterial transport overrode the effect of irrigation. The ‘seasonal condition’ of the soil (including variation in initial water content) also influenced bacterial leaching, with less risk of leaching in autumn than in summer. A tension infiltrometer experiment measured hydraulic conductivity of the lysimeters at zero and 40 mm suction. The results showed in most cases a significant correlation between the proportion of bacteria leached and the flow contribution of the macropores. The higher the Ksat, the greater the amount of drainage and bacterial leaching obtained. This research also found that this technique may exclude the activity of some continuous macropores (e.g., cracks) due to the difference of initial wetness which could substantially change the conductivity and result in more serious bacterial leaching in this Templeton soil. A dye infiltration study showed there was great variability in water flow patterns, and most of the flow reaching deeper than 50 cm resulted from macropores, mainly visible cracks. The transient water flow and transport of tracer (Br⁻) and FC were modelled using the HYDRUS-1D software package. The uniform flow van Genuchten model, and the dual-porosity model were used for water flow and the mobile-immobile (MIM) model was used for tracer and FC transport. The hydraulic and solute parameters were optimized during simulation, on the basis of measured datasets from the leaching experiments. There was evidence supporting the presence of macropores, based on the water flow in the post-DSE application stage. The optimised saturated water content (θs) decreased during the post-application process, which could be explained in terms of macropore flow enhanced by irrigation. Moreover, bacterial simulation showed discrepancies in all cases of uniform flow simulations at the very initial stage, indicating that non-equilibrium processes were dominant during those short periods, and suggesting that there were strong dynamic processes involving structure change and subsequently flow paths. It is recommended that management strategies to reduce FC contamination following application of DSE in these soils must aim to decrease preferential flow by adjusting irrigation schemes. Attention needs to be given to a) decreasing irrigation rates at the beginning of each irrigation; b) increasing the number of irrigations, by reducing at the same time the amount of water applied and the irrigation rate at each irrigation; c) applying spray irrigation rather than flood irrigation.

L'objectif de ce travail est de contribuer à la modélisation globale du système veineux jambier entrepris par les Laboratoires Innothera, en étudiant deux de ces aspects singuliers. La première partie porte sur les confluences. A l'aide d'une étude numérique validée expérimentalement nous proposons deux modèles permettant, d'une part de prédire la perte de charge singulière d'une confluence en fonction de sa géométrie et de son régime d'écoulement et, d'autre part, de prendre en compte les effets non newtoniens du sang en introduisant une viscosité dont la valeur dépend du débit. La seconde partie porte sur le remplissage et la vidange d'un tuyau souple. A l'aide d'un banc hydrodynamique nous avons développé une méthode de mesure de loi d'état de ces tuyaux et un modèle rendant compte de la cinématique de leur paroi. Enfin, nous avons réalisé la validation d'un code de simulation numérique permettant de résoudre le problème de l'écoulement d'un fluide dans une conduite déformable.

La Corse est riche en Plantes à Parfum, Aromatiques et Médicinales (PPAM) dont les huiles essentielles sont susceptibles d'être utilisées dans différents domaines. La composition de ces dernières permet de les caractériser, d'en évaluer la qualité, de mettre en évidence une éventuelle spécificité locale et, ce faisant, de les valoriser. Deux objectifs majeurs ont été fixés à ce travail de thèse portant sur les huiles essentielles et les fractions volatiles de trois plantes des littoraux de Corse et de Sardaigne : Chamaemelum mixtum, Anthemis maritima et Eryngium maritimum : (i) Un objectif fondamental : accroître notre connaissance des constitutions chimiques des huiles essentielles et fractions volatiles des trois espèces, en adaptant en tant que de besoin, la méthodologie d'analyse adoptée au laboratoire ; méthodologie basée sur la complémentarité de diverses techniques (CC, CPG/DIF, CPG/SM-IE, CPG/SM-IC et RMN 1D et 2D). (ii) Un objectif plus appliqué : évaluer le potentiel de valorisation à travers l'étude des variabilités des huiles essentielles, mais également, à travers la recherche d'activités antibactériennes et antifongiques. Dans l'huile essentielle de Chamaemelum mixtum qui présente une composition chimique différente des huiles essentielles du Maroc décrites dans la littérature, nous avons isolé et identifié une nouvelle cétone linéaire la (Z)-heptadéc-9,16-adièn-7-one. La composition chimique de l'huile essentielle d'Anthemis maritima riche en esters de chrysanthényle est ici rapportée pour la première fois. Après avoir élaboré une stratégie d'analyse originale, nous avons décrit une série de 14 esters des cis- et trans-chrysanthénol. Un grand nombre d'entre eux n'avaient encore jamais été décrits en RMN. L'huile essentielle d'Eryngium maritimum est, également, décrite pour la première fois de façon aussi exhaustive. Nous avons identifié : le 4-muurol-9-èn-15-ol, le 4-cadin-9-èn-15-ol et le 4-cadin-9-èn-15-al, composés naturels jamais décrits jusque là, ainsi que le 4-muurol-9-èn-15-al dont les données RMN sont rapportées ici pour la première fois. Les trois huiles essentielles et plus particulièrement celle de Chamaemaelum mixtum se sont avérées actives contre un panel de micro-organismes impliqués dans les infections nosocomiales et alimentaires. L'étude de variabilité liée à la géographie, montre la présence de plusieurs groupes statistiques pour chacune des trois plantes et plus spécifiquement pour Anthemis maritima qui admet deux types de compositions chimiques tranchés. Les compositions chimiques des huiles essentielles et fractions volatiles captées par MEPS des divers organes de chaque plante ont également été décrites. Nos résultats confortent la MEPS comme outil analytique rapide et fiable d'acquisition du profil chimique d'une fraction volatile.

Dans ce mémoire nous décrivons une expérience de mesure des fluctuations de phase dans des condensats de Bose-Einstein très allongés. Les condensats de Bose-Einstein sont habituellement décrits comme des objets totalement cohérents. Cela est valable dans le cas de condensats peu anisotropes. En revanche, cela n'est plus exact dans des cas très anisotropes, en particulier pour des condensats très allongés dont les états excités de basse énergie sont 1D, et peuvent donc être très peuplés thermiquement même à basse température. Cette population d'excitations de faible énergie résulte en des fluctuations de la phase, et donc en une réduction de la longueur de cohérence du condensat dans la direction allongée, tandis que son profil de densité n'est pas perturbé. On parle alors de quasi-condensat. Pour mesurer les fluctuations de phase, nous utilisons la spectroscopie de Bragg. Cette méthode donne accès à la distribution en impulsion des atomes du quasi-condensat, et donc par transformée de Fourier, à sa fonction de corrélation. On peut ainsi en déduire sa longueur de cohérence. Nos mesures montrent une distribution en impulsion lorentzienne, dont la largeur augmente avec la température. Cela signifie que nous observons une perte de cohérence, à mesure que la température augmente, en accord quantitatif avec les prédictions théoriques. Nous étudions également le profil de densité des quasi-condensats. Aucune différence avec le cas de condensats cohérents n'a pu être mesurée, ce qui confirme l'absence de fluctuations de densité importantes dans les quasi-condensats.

Made available in DSpace on 2015-03-13T17:08:18Z (GMT). No. of bitstreams: 1 FabioEMR_Capa_ate_Cap3.pdf: 2956379 bytes, checksum: e1a356dd8141f0ac9ce3d477be9710dc (MD5) Previous issue date: 2009-02-27 / This study has as a main objective to make a detailed stratigraphic analysis of the Aptian-Albian interval in the east part of Araripe Basin, NE of Brazil which correspond, litostratigraphically, to Rio Da Batateira, Crato, Ipubi and Romualdo formations. The stratigraphic analysis was based on three different stages, the 1D, 2D and 3D analysis; these ones were adapted to the sequence stratigraphy concepts in order to create a chronostratigraphic framework for the study area within the basin. The database used in the present study contains field and well information, wells that belong to Santana Project, carried out by the Minist?rio de Minas e Energia- DNPM- CPRM from 1977 to 1978. The analysis 1D, which was done separately for each well and outcrop allowed the recognition of 13 sedimentary facies, mainly divided based on predominant litologies and sedimentary structures. Such facies are lithologically represented by pebble, sandstones, claystones, margas and evaporates; these facies are associated in order to characterize different depositional systems, that integrate from the continental environment (fluvial system and lacustre), paralic system (delta system and lagunar) to the marine environment (shelfenvironment). The first one, the fluvial system was divided into two subtypes: meandering fluvial system, characterized by fill channel and floodplain deposits; the facies of this system are associated vertically according to the textural thinning upward cycles (dirting-up trend pattern in well logs). Lacustrine environment is mainly related with the lithotypes of the Crato Formation, it shows a good distribution within the basin, been composed by green claystone deposits and calcareous laminated. Deltaic System represented by prodelta and delta front deposits which coarsening upward tendency. Lagunar system is characterised by the presence of anhydrite and gypsum deposits besides the black claystone deposits with vegetal fragments which do not contain a fauna typically marine. The marine platform system is composed by successions of black and gray claystone with fossiliferous fauna of Dinoflagellates (Spiniferites Mantell, Subtilisphaera Jain e Subtilisphaera Millipied genre) typical of this kind of depositional system. The sedimentary facies described are vertically arranged in cycles with progradational patterns which form textural coersening upward cycles and retrogradational, represented by textural thinning dowward cycles. Based in these cycles, in their stack pattern and the vertical change between these patterns, the systems tracks and the depositional sequences were recognized. The Low System Track (LST) and High System Track (HST) are composed by cycles with progradational stack pattern, whereas the Trangessive System Track (TST) is composed by retrogradational stack pattern cycles. The 2D stratigraphic analysis was done through the carrying out of two stratigraphic sections. For the selection of the datum the deepest maximum flooding surface was chosen, inside the Sequence 1, the execution of these sections allowed to understand the behaviour of six depositional systems along the study area, which were interpreted as cycles of second order or supercycles (cycles between 3 and 10 Ma), according to the Vail, et al (1977) classification. The Sequence 1, the oldest of the six identified is composed by the low, transgressive and high systems tracks. The first two system tracks are formed exclusively by fluvial deposits of the Rio da Batateira Formation whereas the third one includes deltaic and lacustrine deposits of the Crato Formation. The sequences 2 and 3 are formed by the transgressive systems tracks (lake spreading phase) and the highstand system track (lake backward phase). The TST of these sequences are formed by lacustrine deposits whereas HST contains deltaic deposits, indicating high rates of sedimentary supply at the time of it s deposition. The sequence 4 is composed by LST, TST and HST, The TST4 shows a significant fall of the lake base level, this track was developed in conditions of low relation between the creation rate of space of accommodation and the sedimentary influx. The TST4 marks the third phase of expansion of the lacustrine system in the section after the basin?s rift, the lacustrine system established in the previous track starts a backward phase in conditions that the sedimentary supply rate exceeds the creation rate of space accommodation. The sequence 5 was developed in two different phases, the first one is related with the latest expansion stage of the lake, (TST5), the basal track of this sequence. In this phase the base level of the lake rose considerably. The second phase (related to the TST5) indicates the end of the lacustrine domain in the Araripe Basin and the change to lagunar system ant tidal flat, with great portions in the supratidal. These systems were formed by restricted lagoons, with shallow level of water and with intermittent connections with the sea. This, was the phase when the Araripe Basin recorded the most several arid conditions of the whole interval studied, Aptian Albian, conditions that allow the formation of evaporitic deposits. The sequence 6 began its deposition after a significant fall of the sea (LST6). The sequence 6 is without any doubtlessly, the sequence that has deposits that prove the effective entrance of the sea into the Araripe Basin. The TST6, end of this sequence, represents the moment which the sea reaches its maximum level during the Aptian Albian time. The stratigraphic analysis of the Aptian Albian interval made possible the understanding that the main control in the development of the depositional sequences recognized in the Araripe Basin were the variations of the local base level, which are controlled itself by the climate changes / O presente trabalho tem como objetivo principal realizar uma an?lise estratigr?fica detalhada do intervalo Aptiano ao Albiano na parte leste da Bacia do Araripe, NE do Brasil, o qual corresponde, litoestratigraficamente, ?s forma??es Rio da Batateira, Crato, Ipub? e Romualdo. A an?lise estratigr?fica envolveu tr?s etapas distintas, a an?lise 1D, 2D e 3D, nas quais foram adaptados os conceitos da estratigrafia de seq??ncias visando elaborar um arcabou?o de car?ter cronoestratigr?fico para a por??o estudada da bacia. Tal estudo contou com uma base de dados integrada por informa??o de campo e de po?os pertencentes ao projeto Santana, realizado pelo Minist?rio de Minas e Energia- DNPM- CPRM nos anos de 1977 e 1978. A an?lise 1D, por meio da an?lise individual de cada afloramento e po?o, permitiu o reconhecimento de 13 f?cies sedimentares, individualizadas com base principalmente nas litologias predominantes e nas estruturas sedimentares. Tais f?cies s?o representadas litologicamente por conglomerados, arenitos, pelitos, calc?rios, margas e evaporitos. As mesmas se associam de forma a caracterizar diferentes sistemas deposicionais, que integram desde o ambiente continental (sistemas fluvial e lacustre), ambiente par?lico (sistemas deltaico e lagunar) at? o ambiente marinho (sistema plataformal). O primeiro deles, o sistema fluvial, foi dividido em dois sub-tipos: o sistema fluvial meandrante, caracterizado por dep?sitos de preenchimento de canal e dep?sitos de plan?cie de inunda??o, e o sistema fluvial entrela?ado formado principalmente por dep?sitos de preenchimento de canal; as f?cies deste sistema se associam verticalmente segundo ciclos de afinamento textural para o topo (padr?o em sino nos perfis geof?sicos). O sistema lacustre, relacionado principalmente aos lit?tipos da Forma??o Crato, apresenta uma boa distribui??o na bacia, sendo composto por dep?sitos de pelitos verdes e calc?rios laminados. O sistema deltaico, representado por dep?sitos de prodelta e de frente deltaica, os quais se disp?em verticalmente em ciclos com granocresc?ncia para o topo (padr?o em sino invertido nos perfis geof?sicos). O sistema lagunar caracteriza-se pela presen?a de dep?sitos de anidrita e gipsita, al?m dos dep?sitos de pelitos negros com restos vegetais, os quais n?o cont?m uma fauna tipicamente marinha. O sistema de plataforma marinha ? composto por sucess?es de pelitos pretos e cinza com faunas fossiliferas de Dinoflagelados (g?neros Spiniferites Mantell, Subtilisphaera Jain e Subtilisphaera Millipied), t?picas de este tipo de sistema deposicional. As f?cies sedimentares descritas se arranjam verticalmente de forma a compor ciclos com padr?es de empilhamento progradacional, os quais formam ciclos com engrossamento textural para o topo, e retrogradacional, representados por ciclos com afinamento textural para o topo. Com base nestes ciclos, em seus padr?es de empilhamento e na mudan?a verticais entre estes padr?es, foram reconhecidos os tratos de sistemas e as seq??ncias deposicionais. Os tratos de sistemas de N?vel Baixo e o de N?vel Alto s?o compostos por ciclos com padr?o de empilhamento progradacional; o Trato de Sistemas Transgressivo, por sua vez, ? formado por ciclos com padr?o de empilhamento retrogradacional. A an?lise estratigr?fica 2D foi elaborada por meio da realiza??o de duas se??es estratigr?ficas. Para a escolha do datum foi privilegiada a superf?cie de m?xima inunda??o mais basal, interna ? Seq??ncia 1. A elabora??o destas se??es possibilitou compreender o comportamento de seis seq??ncias deposicionais ao longo da ?rea de estudo, as quais foram interpretadas como ciclos de segunda ordem ou superciclos (ciclos com dura??es entre 3 e 10 Ma), segundo a classifica??o de Vail, et al (1977). A Seq??ncia 1, mais antiga das seis seq??ncias identificadas, ? composta pelos tratos de sistemas de N?vel Baixo, Transgressivo e de N?vel Alto. Os dois primeiros tratos s?o formados exclusivamente pelos dep?sitos fluviais da Forma??o Rio da Batateira, ao passo que o terceiro inclui dep?sitos deltaicos e lacustres da Forma??o Crato. As seq??ncias 2 e 3 s?o formadas pelos tratos de sistemas Transgressivo (TST; fase de expans?o do lago) e de N?vel Alto (TSNA; fase retra??o do lago). Os TST s destas seq??ncias s?o formados por dep?sitos lacustres, ao passo que os TSNA s cont?m dep?sitos deltaicos, indicando assim condi??es de alta taxa de suprimento sedimentar na ?poca da deposi??o deste. A seq??ncia 4 ? formada pelos tratos de sistemas de N?vel Baixo (TSNA), Transgressivo e de N?vel Alto. O TSNB registra uma queda importante do n?vel base do lago; este trato se desenvolveu em condi??es de baixa raz?o entre a taxa de cria??o de espa?o de acomoda??o e a taxa de influxo sedimentar. O TST marca a terceira fase de expans?o do sistema lacustre na se??o p?s rifte da bacia; o sistema lacustre implantado no trato anterior inicia uma fase de retra??o em condi??es em que a taxa de aporte sedimentar passa a suplantar a de cria??o de espa?o de acomoda??o. A seq??ncia 5 desenvolveu-se em duas fases distintas. A primeira relaciona-se com a ?ltima etapa de expans?o do lago, (TST), trato basal desta seq??ncia. Nesta fase, o n?vel base do lago subiu consideravelmente. A segunda fase, relacionada ao TSNA), indica o final do dom?nio lacustre na Bacia do Araripe e a mudan?a para sistemas lagunares e de plan?cie de mar?, com grande desenvolvimento das por??es de supramar?. Estes sistemas eram formados por lagunas restritas, com l?mina de ?gua rasa, e com conex?o intermitente com o mar. Esta foi a fase em que a Bacia do Araripe registrou as mais severas condi??es de aridez de todo intervalo estudado, Aptiano ao Albiano, condi??es estas que propiciaram a forma??o de dep?sitos evapor?ticos. A seq??ncia 6 iniciou sua deposi??o ap?s uma queda significativa do incipiente mar (TSNB). Esta seq??ncia ?, indubitavelmente, a que cont?m os dep?sitos que comprovam a efetiva entrada do mar na Bacia do Araripe. O TST, trato final desta seq??ncia, representa o momento em que o n?vel do mar atingiu o seu m?ximo durante todo o intervalo Aptiano ao Albiano. A an?lise estratigr?fica do intervalo Aptiano ao Albiano permitiu compreender que o controle principal no desenvolvimento das seq??ncias deposicionais reconhecidas na Bacia do Araripe foram ?s varia??es do n?vel de base local, as quais s?o controladas, por sua vez, pelas mudan?as clim?ticas

<p>One of the major challenges in the field of internal combustion engines is keeping up with the advancements in electrification and hybridization. Automakers are striving to design environment – friendly and highly efficient engines to meet stringent emission standards worldwide. Improving engine efficiency and reducing heat losses are critical aspects of this development. Therefore, accurate heat transfer prediction capabilities play a vital role in engine design process. Current methods rely on computationally intensive 3D numerical analyses, there is a growing interest in reliable simplified models. </p> <p>In this study, a 1D diesel engine model featuring predictive combustion was integrated with a detailed finite element thermal primitive based on the 3D meshing feature available in GT Suite. Coolant and oil hydraulic circuits were incorporated in the model. The model proves to be an effective means to assess the impact on heat rejection and engine heat distribution given by an engine calibration and operating conditions. </p> <p>This work also contributes to the advancement of virtual IC engine development methods by focusing on the design and tuning of complex engine system models using GT Power for accurate prediction of engine performance. The current processes in engine simulations are assessed to identify sources of errors and opportunities for improvements. The methods discussed in this work include isolated sub system level calibration and model evolution specifically address the issue of identifying noise factors and issues in smaller parts. Additionally, the study aims on improving the model’s trustworthiness by computing 1st law sanity checks, replicating real-life compressor map calculations and refining GT’s existing global convergence criteria. </p>

No description available.

[ES] El transporte por carretera es uno de los sectores que más contribuyen al cambio climático. Por ello, muchos gobernantes a nivel mundial están promoviendo una transición hacia medios de transporte sostenibles que no dependan de combustibles fósiles. Sin embargo, debido a la falta de competitividad de las alternativas actuales, no parece factible, en el corto plazo, reducir significativamente el uso de los motores de combustión. Así pues, es probable que los motores de gasolina (MEP) mantengan su papel dominante en el sector automotriz durante los próximos años. De ahí que sea crucial seguir mejorando estos motores a fin de reducir su huella de carbono. Actualmente, es habitual fabricar motores MEP de pequeña cilindrada ("downsizing") con sistemas de sobrealimentación e inyección directa, a fin de reducir el consumo de combustible y las emisiones de CO2. Además, en la última década, se ha demostrado que la recirculación de gases de escape (EGR) puede mejorar la eficiencia de los motores MEP entre un 3 % y un 6 %, dependiendo del grado de carga. Como desventaja, para poder extraer todo el potencial de la estrategia EGR, es necesario trabajar con altas tasas de EGR, lo que puede causar ciertos problemas en condiciones transitorias. En esta tesis, se ha demostrado que el uso de altas tasas de EGR a través de sistemas de baja presión en motores MEP turboalimentados puede ralentizar la respuesta del motor y provocar fallos de encendido durante maniobras de aceleración y desaceleración, respectivamente. Con la entrada en vigor de nuevos procedimientos de homologación de vehículos, como el WLTP (Worldwide harmonized Light vehicle Test Procedure), donde las operaciones transitorias tienen un peso importante, los fabricantes buscan que sus motores consuman y emitan menos en un amplio rango de condiciones de operación, tanto estacionarias como transitorias. Por ello, el objetivo principal de esta tesis es analizar y optimizar el funcionamiento, en condiciones transitorias, de los motores MEP que operan con altas tasas de EGR. Para ello, se ha empleado un motor de gasolina (Euro 6) de 1.3l turboalimentado con inyección directa, distribución variable y turbina de geometría variable. Se ha desarrollado un modelo unidimensional (1D) del motor para el estudio de la fluidodinámica y los fenómenos de transporte en su interior. Por otro lado, se ha ensayado el motor para calibrar el modelo 1D y evaluar aspectos difícilmente predecibles con dicho modelo, como las emisiones contaminantes y la estabilidad de la combustión. Previo al estudio en condiciones transitorias, el motor fue calibrado con EGR, y se realizaron simulaciones para determinar el consumo de un vehículo convencional y otro híbrido, ambos con EGR, durante un ciclo WLTP. Finalmente, se concluyó que ciertas estrategias orientadas a mejorar el proceso de renovación de la carga pueden resolver la problemática del uso del EGR en condiciones transitorias. Eso sí, implementar dichas estrategias conllevaría un aumento en complejidad y costes. / [CA] El transport per carretera és un dels sectors que més contribueixen al canvi climàtic. Per això, molts governants a nivell mundial estan promovent una transició cap a mitjans de transport sostenibles que no depenguen de combustibles fòssils. No obstant això, a causa de la falta de competitivitat de les alternatives actuals, no sembla factible, en el curt termini, reduir significativament l'ús dels motors de combustió. Així doncs, és probable que els motors de gasolina (MEP) mantinguen el seu paper dominant en el sector automotriu durant els pròxims anys. D'ací ve que siga crucial continuar millorant aquests motors a fi de reduir la seua petjada de carboni. Actualment, és habitual fabricar motors MEP de xicoteta cilindrada ("downsizing") amb sistemes de sobrealimentació i injecció directa, a fi de reduir el consum de combustible i les emissions de CO2. A més, en l'última dècada, s'ha demostrat que la recirculació de gasos d'escapament (EGR) pot millorar l'eficiència dels motors MEP entre un 3% i un 6%, depenent del grau de càrrega. Com a desavantatge, per a poder extraure tot el potencial de l'estratègia EGR, és necessari treballar amb altes taxes de EGR, la qual cosa pot causar uns certs problemes en condicions transitòries. En aquesta tesi, s'ha demostrat que l'ús d'altes taxes de EGR a través de sistemes de baixa pressió en motors MEP turboalimentats pot alentir la resposta del motor i provocar fallades d'encesa durant maniobres d'acceleració i desacceleració, respectivament. Amb l'entrada en vigor de nous procediments d'homologació de vehicles, com el WLTP (Worldwide harmonized Light vehicle Test Procedure), on les operacions transitòries tenen un pes important, els fabricants busquen que els seus motors consumisquen i emeten menys en un ampli rang de condicions d'operació, tant estacionàries com transitòries. Per això, l'objectiu principal d'aquesta tesi és analitzar i optimitzar el funcionament, en condicions transitòries, dels motors MEP que operen amb altes taxes de EGR. Per a això, s'ha emprat un motor de gasolina (Euro 6) de 1.3l turboalimentat amb injecció directa, distribució variable i turbina de geometria variable. S'ha desenvolupat un model unidimensional (1D) del motor per a l'estudi de la fluidodinàmica i els fenòmens de transport en el seu interior. D'altra banda, s'ha assajat el motor per a calibrar el model 1D i avaluar aspectes difícilment predictibles amb aquest model, com les emissions contaminants i l'estabilitat de la combustió. Previ a l'estudi en condicions transitòries, el motor va ser calibrat amb EGR, i es van realitzar simulacions per a determinar el consum d'un vehicle convencional i un altre híbrid, tots dos amb EGR, durant un cicle WLTP. Finalment, es va concloure que unes certes estratègies orientades a millorar el procés de renovació de la càrrega poden resoldre la problemàtica de l'ús del EGR en condicions transitòries. Això sí, implementar aquestes estratègies comportaria un augment en complexitat i costos. / [EN] Road transport is a major contributor to climate change. However, given the lack of competitiveness of fossil fuel-free alternatives, it does not seem possible to reduce the dependence on the internal combustion engine (ICE) as rapidly as planned by the authorities. Advanced gasoline engines will therefore hold a high market share in the automobile industry in the following years, at least during the next decade, either working in conventional or hybrid powertrains. Hence it is essential to keep improving these engines to reduce the negative impact of light-duty vehicles on the environment. The most used strategy to reduce fuel consumption and CO2 emissions in current spark-ignition (SI) gasoline engines is downsizing combined with direct injection (DI). Besides, downsizing must go hand in hand with turbocharging to maintain peak power. It is also proven that exhaust gas recirculation (EGR) can improve fuel economy in SI engines by 3-6% at medium and high loads. As a disadvantage, extracting the full benefit from EGR requires operating with high recirculation rates (close to the EGR dilution limit), leading to some issues under transient conditions. In this thesis, it is demonstrated that high EGR operation through long-route systems in turbocharged engines can potentially originate combustion instabilities and poor engine response during load-decrease (tip-out) and load-increase (tip-in) maneuvers, respectively. Transient operations are especially important for manufacturers since the implementation of the Worldwide harmonized Light vehicle Test Procedure (WLTP). The present thesis is therefore devoted to analyzing and optimizing the gasoline engine performance under high EGR conditions during relevant transient maneuvers. To this end, a Euro-6 1.3L turbocharged DI SI gasoline engine with a variable geometry turbine was employed. A 1D model of this ICE was developed to assess fluid dynamics and transport phenomena. Engine tests were also performed to validate the 1D model and evaluate torque response, combustion stability, and raw exhaust emissions. Before addressing the study of transient maneuvers, the engine calibration with EGR was carried out, and 0D conventional and hybrid vehicle simulations were done to determine the EGR benefit in fuel economy under WLTP driving conditions. Finally, tip-in and tip-out results revealed that some air management strategies are effective in meeting the transient EGR challenges in SI engines, but at the expense of increased complexity and costs. / González Domínguez, D. (2023). Analysis and Optimization of the Transient Operation of Gasoline Turbocharged Direct Injection Engines Under High EGR Conditions [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/193852

Seafloor compliance is a non-intrusive geophysical method sensitive to the shear modulus of the sediments below the seafloor. A compliance analysis requires the computation of the frequency dependent transfer function between the vertical stress, produced at the seafloor by the ultra low frequency passive source-infra-gravity waves, and the resulting displacement, related to velocity through the frequency. The displacement of the ocean floor is dependent on the elastic structure of the sediments and the compliance function is tuned to different depths, i.e., a change in the elastic parameters at a given depth is sensed by the compliance function at a particular frequency. In a gas hydrate system, the magnitude of the stiffness is a measure of the quantity of gas hydrates present. Gas hydrates contain immense stores of greenhouse gases making them relevant to climate change science, and represent an important potential alternative source of energy. Bullseye Vent is a gas hydrate system located in an area that has been intensively studied for over 2 decades and research results suggest that this system is evolving over time. A partnership with NEPTUNE Canada allowed for the investigation of this possible evolution. This thesis describes a compliance experiment configured for NEPTUNE Canada’s seafloor observatory and its failure. It also describes the use of 203 days of simultaneously logged pressure and velocity time-series data, measured by a Scripps differential pressure gauge, and a Güralp CMG-1T broadband seismometer on NEPTUNE Canada’s seismic station, respectively, to evaluate variations in sediment stiffness near Bullseye. The evaluation resulted in a (- 4.49 x10-3± 3.52 x 10-3) % change of the transfer function of 3rd October, 2010 and represents a 2.88% decrease in the stiffness of the sediments over the period. This thesis also outlines a new algorithm for calculating the static compliance of isotropic layered sediments.