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Hledání fosfoproteinů účastnících se aktivace pylu tabáku in vitro / Revealing phosphoproteins playing role in tobacco pollen activated in vitroFíla, Jan January 2012 (has links)
5 Abstract Tobacco mature pollen rehydrates in vivo on a stigma tissue, and develops into the rapidly-growing pollen tube. This rehydration process is accompanied by the de-repression of stored mRNA transcripts, resulting in the synthesis of novel proteins. Furthermore, such metabolic switch is also likely to be regulated on the level of post-translational modifications of the already-present proteins, namely via phosphorylation, since it was shown to play a significant regulatory role in numerous cellular processes. Since only a minor part of proteins is phosphorylated in a cell at a time, the employment of various enrichment techniques is usually of key importance. In this diploma project, metal oxide/hydroxide affinity chromatography (MOAC) with aluminium hydroxide matrix was applied in order to enrich phosphoproteins from the mature pollen and the 30-minute in vitro activated pollen crude protein extracts. The enriched fraction was separated by both 2D-GE and gel-free liquid chromatography (LC) approaches with subsequent mass spectrometric analyses. Collectively, 139 phosphoprotein candidates were identified. Additionally, to broaden the number of phosphorylation sites identified, titanium dioxide phosphopeptide enrichment of trypsin-digested mature pollen crude extract was performed. Thanks to the...
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Sulphate‐reducing bacterial diversity in a calcareous sandy sediment of Mallorca and community response to hydrocarbon contaminationSuárez Suárez, Ana Belén 25 July 2012 (has links)
Aquesta tesi tracta sobre l'efecte de la contaminació per cru de petroli sobre
l'ecosistema costaner mediterrani i sobre el paper fonamental dels sediments marins
en la regulació i el manteniment dels processos biogeoquímics. L'estudi presta especial
atenció a les comunitats bacterianes reductores de sulfat i la seva implicació en la
degradació de contaminants orgànics. La diversitat, abundància i fisiologia dels bacteris
reductors de sulfat que habiten el sediment arenós del nord de Mallorca (Illes Balears),
van ser analitzades mitjançant un enfocament polifàsic, basat en la combinació
d'experiments in situ i in vitro, biologia molecular clàssica i d’última generació, cultius i
determinació d'activitats metabòliques. Els resultats obtinguts durant aquesta tesi
demostren que el sediment mediterrani alberga una microbiota autòctona que podria
prosperar després d'un vessament de cru de petroli i el paper de la qual podria ser
crucial per a la transformació i l'eliminació de compostos orgànics xenobiòtics en
aquest ambient. / Esta tesis trata sobre el efecto de la contaminación por crudo de petróleo en el
ecosistema costero mediterráneo y sobre el papel fundamental de los sedimentos
marinos en la regulación y el mantenimiento de los procesos biogeoquímicos. El
estudio presta especial atención a las comunidades bacterianas reductoras de sulfato y
a su implicación en la degradación de contaminantes orgánicos. La diversidad,
abundancia y fisiología de las bacterias reductoras de sulfato que habitan el sedimento arenoso del norte de Mallorca (Islas Baleares), fueron analizadas mediante un enfoque
polifásico, basado en la combinación de experimentos in situ e in vitro, biología
molecular clásica y de última generación, cultivos y determinación de actividades
metabólicas. Los resultados obtenidos durante esta tesis demuestran que el sedimento
mediterráneo alberga una microbiota autóctona que podría prosperar después de un
derrame de crudo de petróleo y cuyo papel podría ser crucial para la transformación y
la eliminación de compuestos orgánicos xenobióticos en este ambiente. / This thesis discusses the fate and behave of crude oil contamination in the
Mediterranean coastal ecosystem, and the essential role of the marine sediments in
the regulation and maintenance of biogeochemical processes. The study pays
particular attention to the role of sulphate reducing bacterial communities in the
degradation of organic matter and pollutants entering the Mediterranean
environment. A polyphasic approach based in the combination of in situ and in vitro
experiments, next generation and classical molecular biology, cultivation, and the
determination of metabolic activities, provided first insights into the diversity, abundance and physiology of sulphate reducing bacteria inhabiting the undisturbed
sandy sediment at the north of Mallorca (Balearic Islands). The results obtained during
the thesis demonstrate that the undisturbed Mediterranean sediment harbours an
autochthonous microbiota that could prosper after a crude oil spill and which role
might be crucial for the transformation and removal of hazardous organic compounds
in this environment.
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Consecuencias ecológicas del enriquecimiento por materia orgánica procedente de la acuicultura y de vertidos de petróleo en ecosistemas costerosSanz Lázaro, Carlos 11 July 2009 (has links)
El objetivo de esta tesis es estudiar el efecto del enriquecimiento por materia orgánica producida por el cultivo de peces en el mar y por los vertidos de petróleo en el medio marino. Este trabajo intenta explicar las consecuencias ecológicas de los impactos generados por este tipo de contaminación, y en diseñar de test de toxicidad para evaluar la contaminación en el sur de las costas europeas. Específicamente, en relación con el impacto de la acuicultura, los estudios de recuperación durante la Apertura de peces bentónicos de reducción de piscicultura marina, el papel de la depredación en el sistema bentónico dispersión de los residuos y los vínculos horizontales y verticales con un impacto bentónico. / The aim of this thesis is to study the effect of organic matter enrichment produced by marinefinfish farming and oil spills on the marine environment. This work is focused on elucidating theecological consequences of the impact generated by this type of pollution, and on designingtoxictity tests to evaluate pollution for southern European coasts. Specifically, related with aquaculture impact, it studies benthic recovery during open sea fish farming abatement, the role of predation in the benthic system and links horizontal and vertical waste dispersion with benthic impact.
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Ersättning vid upphovsrättsintrång enligt 54 § 1 st. URL : En momspliktig upplåtelse / överlåtelse eller ett skadestånd utan skada? / Compensation for copyright infringement under Article 54 § 1 st. URL : A subject to VAT lease / sale or damages without suffered prejudice?Karlsson, Andreas January 2010 (has links)
Mervärdesskatterättsligt särbehandlas omsättning av upphovsrätter genom tillämpning av en reducerad skattesats. I 7 kap. 1 § 3 st. 8-9 p. ML hänvisas direkt till upphovsrättslagen för bedömningen av förekomsten av en upphovsrättsligt skyddad prestation och rättighetens övergång. Föreligger en mervärdesskatterättslig omsättning av ekonomiska värden samtidigt med en upphovsrättsligt giltig upplåtelse eller överlåtelse av en upphovsrättsligt skyddad prestation ska omsättningen beskattas med en reducerad skattesats om sex procent. Uppsatsen utreder intrångsersättning enligt 54 § 1 st. URL i relation till det mervärdesskatterättsliga omsättningsbegreppet och den reducerade skattesatsen i 7 kap. 1 § 3 st. 8-9 p. ML. Ersättning enligt 54 § 1 st. URL ska erläggas då ett intrång i upphovsrätten kan konstateras. Ersättning ska alltid utgå oavsett god tro och även i fall där upphovsmannen, genom t.ex. positiva sidoeffekter, tjänat på intrånget. I doktrin har det därför uttalats att ersättningen inte utgör skadestånd, något som lagstiftaren uttryckligen klassificerat den att vara. Vid en granskning av ersättningens karaktär och syfte i relation till upphovsrättslagens regler för rättighetens övergång framgår att en upphovsrättsligt giltig överlåtelse eller upplåtelse inte föreligger vid en transaktion som föranlett ersättningsskyldighet enligt 54 § 1 st. URL. Enligt 7 kap. 1 § 3st. 8-9 p. ML är detta en förutsättning för att transaktionen ska omfattas av den reducerade skattesatsen. I ett mervärdesskatterättsligt perspektiv står det emellertid klart att ersättning enligt 54 § 1 st. URL är tänkt att spegla de förhållanden som hade gällt om parterna ingått avtal på förhand och att det finns ett ostridigt samband mellan ersättningens storlek och det faktiska nyttjandet av rättigheten. Således skulle ersättningen mervärdesskatterättsligt kunna jämställas med en upplåtelse av nyttjanderätt. För tillämpning av den reducerade skattesatsen i 7 kap. 1 § 3st. 8-9 p. ML är ett jämställande med upplåtelse ur mervärdesskatterättslig synpunkt emellertid inte tillräckligt. Mervärdesskattelagens ovillkorliga koppling till upphovsrättslagen i 7 kap. 1 § 3st. 8-9 p. ML medför att en upplåtelse ska prövas enligt upphovsrättslagens regler för rättighetens övergång. Den samlade slutsatsen av uppsatsens utredning är följaktligen att ersättning enligt 54 § 1 st. URL kan omfattas av det mervärdesskatterättsliga omsättningsbegreppet. Mervärdesskattelagens ovillkorliga koppling till upphovsrättslagen innebär emellertid att ersättningen inte kan omfattas av 7 kap. 1 § 3st. 8-9 p. ML och den reducerade skattesatsen om 6 procent. Ersättningen utbetalas till följd av ett intrång och avsaknaden av en uttrycklig överenskommelse hindrar en tillämpning av 7 kap. 1 § 3st. 8-9 p. ML. / VAT turnover of copyrights are subject to a reduced VAT-rate. In the Value added tax act (ML) the paragraph of 7 kap. 1 § 3 st. 8-9 p. ML refers directly to the Copyright act (URL) for the assessment of the existence of a copyright and, the sale or lease of such a right. If a taxable supply is at hand while, simultaneously, a legally valid lease or sale of a copyright can be established, the turnover is taxed at a reduced VAT-rate of six percent. The thesis investigates intrusion compensation under Article 54 § 1 st. URL relative to the value added tax turnover concept and the reduced rate in 7 kap 1 § 3 st. 8-9 p. ML. Compensation according to Article 54 § 1 st. URL must be paid when an infringement of copyright is at hand. Compensation should always be paid regardless of good faith and even in cases where the holder of the right has earned revenue by e.g. spin-offs. In the legal literature, it has therefore been expressed that Article 54 § 1 st. URL does not constitute damages, something that the legislature explicitly has classified it to be. When reviewing the character and purpose of the compensation in relation to URL, and its rules for the transition of the right, it is clear that a valid transition does not exist in a transaction that has prompted compensation under Article 54 § 1 st. URL. According to 7 kap. 1 § 3st. 8-9 p. ML, this is a prerequisite. For the transaction to be covered by the reduced VAT-rate, a valid transition, according to the general rules of the rights transition in URL, must be at hand. However, from a VAT-perspective, compensation under 54 § 1 st. URL is meant to reflect the conditions that would have been if the concerned parties had reached an agreement in advance. There is an undisputed link between the remuneration and the actual use of the right. Thus, the compensation could be deemed equal to a lawful lease of copyright. For the purposes of the reduced tax rate in 7 kap. 1 § 3st. 8-9 p. ML, an equation of the compensation to a lawful lease of copyright is not sufficient. The provision is directly connected to URL and any transition of copyright must therefore be examined under the URL's rules for the transition of rights. The overall conclusion of this thesis is therefore that compensation under 54 § 1 st. URL may be subject to VAT. However, due to the unconditional connection to URL, the turnover cannot qualify for the reduced tax rate of six percent stipulated in 7 kap. 1 § 3st. 8-9 p. ML. The compensation is paid as a result of an infringement of copyright and the absence of an explicit agreement prevents the application of the reduced tax rate in 7 kap. 1 § 3st. 8-9 p. ML.
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Essays on the Effect of Climate Change on Agriculture and Agricultural TransportationAttavanich, Witsanu 2011 December 1900 (has links)
This dissertation analyzes the impact of climate, and atmospheric carbon dioxide (CO2) on crop yields and grain transportation. The analysis of crop yields endeavors to advance the literature by statistically estimating the effects of atmospheric carbon dioxide (CO2) on observed crop yields. This is done using an econometric model estimated over pooled historical data for 1950-2009 and data from the free air CO2 enrichment experiments. The main findings are: 1) yields of soybeans, cotton, and wheat directly respond to the elevated CO2, while yields of corn and sorghum do not; 2) the effect of crop technological progress on mean yields is non-linear; 3) ignoring atmospheric CO2 in an econometric model of crop yield likely leads to overestimates of the pure effects of climate change and technological progress on crop yields; and 4) average climate conditions and climate variability contribute in a statistically significant way to average crop yields and their variability.
To examine climate change impacts on grain transportation flows, this study employs two modeling systems, a U.S. agricultural sector model and an international grain transportation model, with linked inputs/outputs. The main findings are that under climate change: 1) the excess supply of corn and soybeans generally increases in Northern U.S. regions, while it declines in Central and Southern regions; 2) the Corn Belt, the largest producer of corn in the U.S., is anticipated to ship less corn; 3) the importance of lower Mississippi River ports, the largest current destination for U.S. grain exports, diminishes under the climate change cases, whereas the role of Pacific Northwest ports, Great Lakes ports, and Atlantic ports is projected to increase; 4) the demand for grain shipment via rail and truck rises, while demand for barge transport drops.
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Strukturelle Merkmale N-modifizierter Braunkohlen unter besonderer Berücksichtigung der Huminstoffe / Structural properties of N-modified brown coals with emphasis on humic substancesNinnemann, Horst 14 January 2008 (has links) (PDF)
Motiviert durch die Zunahme der weltweiten Nachfrage nach hochwertigen Humusstoffen wurde am Institut für Holz- und Pflanzenchemie ein neuartiger Humusersatzstoff entwickelt. Dieses N-modifizierte Produkt wird auf Basis eines patentierten Normaldruckverfahrens der oxidativen Ammonolyse (OA) aus ligninhaltigen Ausgangssubstanzen, im vorliegenden Fall Lausitzer Braunkohle, hergestellt. Ziel war, die bisher vorliegenden Erkenntnisse der strukturellen Eigenschaften solcher Humusstoffe zu erweitern. Im Fokus standen die Gehalte und Charakteristik der Huminstofffraktionen (Humine, Humin- und Fulvosäuren). Der Stickstoff und die Art seines Einbaus in die organische Substanz spielt hierbei eine besondere Rolle. Für die Huminstoffisolierung kam die hinsichtlich der Ausbeuten und des Zeitaufwandes optimierte IHSS-Methode zum Einsatz. Wesentliche Merkmale N-modifizierter Substanzen sind erhöhte Huminsäurengehalte, zeitlich differenziert wirksame N-Bindungsformen und damit eine Diversifizierung der Funktionalität. Zusätzlich mit dem geringen Aschegehalt unterscheidet dies N-modifizierte Lausitzer Braunkohle von anderen auf Braunkohlebasis erzeugten Bodenverbesserungsmitteln des Marktes. Es konnte gezeigt werden, dass Huminsäuren hinsichtlich der Bereitstellung von Stickstoff und Funktionalität (z.B. Austauscherplätze) eine Schlüsselrolle einnehmen. Die Veränderungen durch die OA basieren stofflich auf der Bildung regenerierter Huminsäuren und chemisch u.a. auf der oxidativen Ringspaltung von Aromaten an nicht veretherten phenolischer OH-Gruppen von Methoxyphenolstrukturen. Dabei ist diese Reaktion entgegen früherer Annahmen nicht an eine Demethoxylierung gebunden und erfordert auch keine verschärften Reaktionsbedingungen (z.B. erhöhter Druck). Diese und weitere Reaktionsmechanismen führen zu ammoniumartig, amidartig und fest organisch gebundenen N-Bindungsformen. 15N-NMR-Spektroskopische Untersuchungen an einem 15N-angereicherten Produkt, Py-GC/MS-Untersuchungen und nasschemische Experimente zeigen, dass in der Vergangenheit die Bedeutung heterocyclischer, insbesondere heteroaromatischer N-Bindungsformen überschätzt wurde. Amidartiger Stickstoff präsentiert sich dabei als außerordentlich heterogen hinsichtlich seiner Hydrolysestabilität bzw. Pflanzenverfügbarkeit. Für die effektive Beurteilung möglicher Ausgangssubstanzen hinsichtlich ihrer Eignung für die Herstellung von Humusdüngestoffen nach dem Prinzip der OA kann der Huminsäurengehalt herangezogen werden. Er wird mit Hilfe eines degradativen Verfahrens ermittelt. Die mit dem Huminsäurengehalt in Verbindung stehenden Stoffeigenschaften von Kohlen korrelieren gut mit dem N-Einbau. Aus Sicht der Verfahrensführung hängt die Intensität des N-Einbaus eng mit dem Oxidationsregime zusammen. Durch Anwendung von reinem Sauerstoff anstelle von Luft als sehr einfach und günstig zu realisierende Maßnahme kann die Reaktionszeit halbiert werden. / The development of a novel artificial humus material at the Institute of Wood- and Plant Chemistry was accounted by the increasing demand for high grade humic matter. This N-modified product base on a patented ambient pressure technology of the oxidative ammonolysis. of lignin containing substances, in particular Lusitian lignite. Objective of the work was to broadening the current knowledge of structural properties with focus on the contents and characteristics of humic substances fractions (humins, humic acids, fulvic acids). Especially attention was given to nitrogen and its way of incorporation into organic matter. For isolating humic substances the IHSS method was used. The procedure was adapted in order to increase the yield of humic acids and decrease time needed. Main characteristics of N-modified substances are higher contents of humic acids and subtly differenciateted effective N-binding forms with leads to higher diversity of the chemical functionality. This and the low ash content makes the differences to other brown coal based soil improving agents available on the marked. It has been shown that humic acids give the main part providing nitrogen and functionality (e.g. cation exchange capacity). The oxidative ammonolysis leads to regenerated humic acids as well as e.g. the clevage of aromatic structures by reactions of free phenolic groups. In contrast to former assumptions the cleavage is not strongly related to demethoxylation or strong reaction conditions like high pressure. This and other reactions lead to short, middle, and long lasting N-binding forms. 15N-NMR-spectroscopic investigations on a 15N-enriched product, Py-GC/MS-investigations and conventional investigations show an overestimation of heterocyclic, in particular heteroaromatic N-binding forms up to now. Consequently amide like nitrogen reveals as extraordinary according to its persistent behaviour to hydrolysis and plant availability respectively. Corresponding the correlation of the N-incorporation and humic acid content of raw materials the latter can be used for evaluating possible raw material for its usage for N-modification. It can be easy obtained in a degratadive way. From the process engineering point of view the success of N-incorporating is strongly correlated to the oxidation conditions during processing. Using pure oxygen instead of air shorts the needed reaction at 50%.
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Structuring habitat to conserve ground beetles (Coleoptera: Carabidae) and reduce summer annual weeds in agroecosystemsGreen, Jessica M. (Jessica Marie) 15 December 2010 (has links)
Weed management in sustainable farming systems often requires the integration of several different pest management techniques. Cultural, biological, and chemical pest control efforts can be utilized to contribute to the common goal of reducing weeds in vegetable row crop systems. This research addresses how common disturbances such as tillage and insecticide use affect: carabid beetle assemblages; predation of weed seeds by invertebrates; and weed seed recruitment. Field experiments were conducted over three years at two different locations on the OSU Vegetable Research Farm, Linn Co., OR. We found that activity-density of carabid beetles varied seasonally and peaked in late August-September each year. Insecticide applied in year 1 affected seed loss in year 2, suggesting possible long-term effects of land management on weed seed removal. Weed recruitment was highly variable between treatment, site, and year. Conserving biological weed control agents in combination with cultural techniques such as reducing tillage and the use of cover crops, helps growers shift from expensive, density-independent control efforts to more ecological, long-term solutions for weed management in agroecosystems. / Graduation date: 2011 / Access restricted to the OSU community, at author's request, from Dec. 15, 2010 - Dec. 15, 2011.
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Use of mouse models to establish genotype-phenotype correlations in Williams-Beuren syndromeSegura Puimedon, Maria, 1985- 20 November 2012 (has links)
Williams-Beuren syndrome (WBS) is a neurodevelopmental disorder caused by the common
deletion of 26-28 contiguous genes in the 7q11.23 region, which poses difficulties to the
establishment of genotype-phenotype correlations. The use of mouse models would broader the
knowledge of the syndrome, the role of deleted genes, affected pathways and possible treatments.
In this thesis project, several mouse models, tissues and cells have been used to define the
phenotypes at different levels, the deregulated genes and pathways and to discover modifying
elements and novel treatments for the cardiovascular phenotype. In addition, a new binding motif
has been described for Gtf2i, a deleted gene encoding a transcription factor with a major role in
WB, providing new target genes from deregulated pathways. The obtained results reveal the
essential role of mouse models for the study of Williams-Beuren syndrome and provide new
treatments options and affected pathways and genes which could be future treatment targets. / La síndrome de Williams-Beuren és una malaltia del neurodesenvolupament causada per una
deleció comú d’entre 26 i 28 gens contigus a la regió 7q11.23, dificultant l’establiment de relacions
genotip-fenotip. L’ús de models de ratolí pot augmentar el coneixement sobre la malaltia, el paper
dels gens delecionats, les vies moleculars afectades i els futurs tractaments. En aquesta tesi s’han
usat diversos models de ratolí, les seves cèl·lules i teixits per tal de descriure i definir fenotips, gens i
vies moleculars desregulades i per descobrir elements modificadors i nous tractaments. Per últim,
s’ha definit un nou motiu d’unió per Gtf2i, uns dels gens delecionats que codifica per un factor de
transcripció amb un rol central en la síndrome, proporcionats possible nous gens diana de vies
moleculars desregulades. Els resultats obtinguts revelen el paper essencial dels models de ratolí per
a l’estudi de la síndrome de Williams-Beuren, proporcionen noves opcions terapèutiques i
defineixen nous gens i vies moleculars afectades que podrien suposar noves dianes terapèutiques.
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Caractérisation expérimentale d’une flamme turbulente non prémélangée swirlée : effet de l’enrichissement en oxygène / Experimental characterization of a non-premixed turbulent swirled flame : effect of oxygen enrichmentMerlo, Nazim 18 December 2014 (has links)
Cette thèse est une contribution à l’étude des flammes de méthane turbulentes non prémélangées en rotation, dites swirlées, avec ou sans enrichissement en oxygène de l’oxydant. L’étude se focalise sur la stabilité de la flamme, les émissions polluantes et la dynamique du jet en non réactif et réactif. Notre dispositif expérimental se compose d’un brûleur à swirler coaxial avec injection radiale de méthane au voisinage de la sortie du brûleur. Ce dernier est confiné dans une chambre de combustion. La teneur en oxygène dans l’oxydant, le nombre de swirl géométrique et la richesse globale à l’injection sont les principaux paramètres qui peuvent être précisément contrôlés. La stabilité de la flamme est caractérisée par chimiluminescence OH*. Les émissions polluantes sont mesurées par des analyseurs en ligne via un prélèvement dans les gaz brûlés. La dynamique du jet est caractérisée principalement par PIV stéréoscopique dans un plan longitudinal et plusieurs plans transverses. La diffusion du méthane dans le jet swirlé est abordée qualitativement par fluorescence induite par laser de l’acétone dans un plan. À ce jour, peu de travaux portent sur la caractérisation notamment dynamique de ces flammes swirlées avec enrichissement en O2. La mise en rotation du jet est à l’origine d’une zone de recirculation centrale qui favorise la stabilisation de la flamme en régime pauvre et à grand nombre de Reynolds. L’étude des émissions polluantes montre que les régimes de combustion à l’air pour lesquels la flamme est liftée stable sont aussi ceux qui produisent du CO et du CH4 résiduel en des quantités non négligeables. L’enrichissement en oxygène permet alors de convertir les imbrûlés et ce pour de faibles enrichissements tout en améliorant la stabilité de flamme via une diminution de la hauteur d’accrochage et des fluctuations associées comme le confirment de précédentes études. L’augmentation des NOx par la voie thermique a été quantifiée pour des enrichissements en oxygène inférieurs à 30 % vol. L’étude systématique en non réactif et réactif apporte des détails sur la topologie tridimensionnelle du jet swirlé suivant les paramètres de l’étude. L’étude de la décroissance des vitesses et de la décroissance du nombre de swirl dans la direction de l’écoulement permetde mettre en évidence l’effet de la flamme sur le jet swirlé. Un couplage entre l’évolution du taux d’entraînement par la recirculation externe et les émissions polluantes est mis en évidence pour expliquer l’évolution des NOx suivant la richesse globale à l’injection. Nous avons proposé une modélisation des écoulements swirlés qui repose sur les écoulements à vorticité hélicoïdale afin d’identifier les caractéristiques principales des structures hélicoïdales au sein de l’écoulement. / This thesis is a contribution to the study of turbulent non-premixed swirling methane flames with or without oxygen addition in the oxidizer. The study deals with the flame stability, the pollutant emissions and the jet dynamic behaviour in non-reacting and reacting conditions. The burner, operating in a combustion chamber, consists of two concentric tubes with a swirler placed in an annular arrangement, which supplied the oxidant flow (air or oxygen-enriched air). The central pipe delivers fuel (methane) radially just below the burner exit plane. The oxygen content in the oxidizer, the geometric swirl number and the global equivalence ratio are the main parameters, which can be precisely set. OH* chemiluminescence imaging is used to characterize flame stability. Multi-gas analyzers are used to measure pollutant emissions in the exhaust gas. The flow is characterized using stereoscopic PIV measurements in different longitudinal and transverse planes. A qualitative study dealing with the methane diffusion imaging is also conducted by use of acetone planar laser-induced fluorescence. Up to now only few studies have examined the dynamic behavior of this type of swirled flames with oxygen addition. Introducing swirl allows creating a central recirculation zone which favors lean flame stabilization at higher Reynolds numbers. The mapping of the combustion regimes combined with the pollutant emission results show that the stable lifted flames are related to high CO and residual CH4 emission levels in the exhaust gas. Oxygen addition, even by a few percent, allows improving CO and unburned hydrocarbons conversion and increasing flame stability at the same time via a decrease of liftoff heights and the related fluctuations. The NOx emissions increase via the thermal pathway with increasing the oxygen-enrichment rate up to 30 % vol. A comparative study in non-reacting and reacting conditions is conducted to give insight into the tridimensional flow field topology varying the above-mentioned parameters. Mean streamwise velocity and swirl number decay rates show the flame effects on the flow dynamics. A coupling mechanism between the entrainment rate of the surroundings via the external recirculation and the pollutant emissions is proposed to explain the NOx emission trend with the global equivalence ratio. A model is also proposed based on the helical vortices to identify the main features of helix structures in the jet in non-reacting and reacting conditions.
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Interface travail-famille et santé psychologique au travail : investigation de la directionalité des liensChampagne, Emilie 12 1900 (has links)
No description available.
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