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Mirza, Muhammad Riaz. "Studies of diesel sprays interacting with cross-flows and solid boundaries." Thesis, University of Manchester, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315666.
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Jones, Alwyn. "The interaction of flames with water sprays." Thesis, Cardiff University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338152.
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Pawlowski, Adam. "Experimental investigation of interaction process between diesel sprays." Aachen Shaker, 2008. http://d-nb.info/992707420/04.
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Cutter, Paul. "Diesel spray characteristics, spray/wall interaction and heat transfer." Thesis, Imperial College London, 1996. http://hdl.handle.net/10044/1/7524.
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Jones, Stephen Huw Meredith. "Interaction of detonation waves with foils and water sprays." Thesis, Cardiff University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.255842.
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Jackman, L. A. "Sprinkler spray interactions with fire gases." Thesis, London South Bank University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.482025.
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Pawlowski, Adam [Verfasser]. "Experimental Investigation of Interaction Processes Between Diesel-Sprays / Adam Pawlowski." Aachen : Shaker, 2009. http://d-nb.info/116131105X/34.
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Palumbo, John C., F. J. Reyes, L. Carey, A. Amaya, and L. Ledesma. "Interactions Between Insecticides, Spray pH, & Adjuvants." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001. http://hdl.handle.net/10150/214912.
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Studies were conducted in the laboratory to investigate how the addition of a insecticides to two sources of Colorado River water would effect the pH of spray mixtures. In addition, we were curious what the effects of various labeled concentrations of buffers, acidifiers, spreader/stickers, and foliar nutrient sprays would have on the pH of spray water. Results showed that in most cases, spray concentration remained alkaline following addition of insecticides and adjuvants, with variations occurring primarily for the OPs. Buffering agents dramatically lowed pH at concentration greater than 0.25% v/v. Studies were also designed to evaluate the knockdown and residual mortality of Success against worms when applied in an acidic spray solution. Bioassays of larval mortality on field-treated foliage showed that knockdown mortality was not affected, but residual efficacy was significantly reduced when Success was applied using acidic (pH 4.2) spray solutions.
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Deprédurand, Valérie. "Approche expérimentale de l'évaporation de sprays de combustibles multicomposant." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL060N/document.
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Des diagnostics optiques non intrusifs ont été utilisés afin d’investiguer les mécanismes gouvernant l’évaporation de trains de gouttes en interaction ou de sprays. Une technique basée sur la fluorescence induite par laser à deux couleurs (2cLIF) du pyrrométhène 597-8C9 ensemencé en très faible concentration dans le liquide à étudier a été développée pour obtenir la température moyenne de gouttes combustibles mono et bicomposant (alcanes, alcool, cétones) évoluant dans un train de gouttes monodisperse. En parallèle, l’évolution du diamètre des gouttes a été déterminée par interférométrie en diffusion avant. L’évolution temporelle de la température et du diamètre des gouttes en évaporation a été mesurée pour une large gamme de paramètres d’injection et d’interaction. Plusieurs combustibles présentant différentes volatilités ont ainsi été étudiés dans une chambre d’évaporation. Les paramètres caractérisant les transferts de chaleur et de masse représentés par les nombres de Nusselt et de Sherwood, intervenant dans le mécanisme d’évaporation des gouttes en interaction, ont été calculés à partir des données expérimentales, ce qui a permis la caractérisation de l’influence des interactions entre gouttes sur les transferts, en mettant en évidence un effet notable de la volatilité du combustible. Ensuite la technique de 2cLIF a été étendue à la mesure de la température moyenne d’un spray de gouttes binaires composées d’un mélange n-décane / 3-pentanone et injecté dans un écoulement turbulent chauffé. Le développement d’une technique de couplage de la technique LIF avec la granulométrie phase Doppler (PDA) a permis la mesure de températures par classe de taille de goutte<br>Non intrusive optical diagnostics are used in order to investigate the mechanisms that govern the droplets evaporation. A new technique based on 2-colours laser-induced fluorescence (LIF) of the pyrromethene 597-8C9 was developed to obtain the mean temperature of evaporating bicomponent fuel droplets in a linear monodisperse droplet stream. In parallel size evolution of the droplet was measured thanks to forward scattering methods. Data on evaporating and interacting droplet streaming linearly have been collected for different injection parameters and several monocomponent fuels (alcohol, ketones, alkanes) that exhibit different volatilities and bicomponent fuels (mixture of n-decane and 3-pentanone), in a temperature controlled evaporation chamber. Heat and mass transfers parameters (Nusselt and Sherwood numbers) involved in the evaporation process of interacting droplets are inferred from the experimental data. The result exhibits a strong influence of the volatilities of the fuel on the effect of the interaction on heat and mass transfers. Then the 2-colours LIF technique was extended to measure the mean temperature within a spray made of bicomponent droplets (n-decane / 3-pentanone), injected in a hot air flow where the turbulence and boundary conditions are controlled. By means of a coupling with the PDA (Particle Dynamic Analyser), temperature for each size of droplets was determined
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Sibra, Alaric. "Modélisation et étude de l’évaporation et de la combustion de gouttes dans les moteurs à propergol solide par une approche eulérienne Multi-Fluide." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLC019/document.
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En propulsion solide, l'ajout de particules d'aluminium dans le propergol améliore de façon significative les performances du moteur grâce à une augmentation sensible de la température de chambre. La présence de gouttes d'aluminium et de résidus d'alumine de différentes tailles et en quantité importante a un impact notoire sur le fonctionnement du moteur. Dans cette optique, nous souhaitons obtenir une meilleure prévision de la stabilité de fonctionnement en cas de déclenchement d'instabilités d'origine aéroacoustique ou thermoacoustique. Nous visons des calculs plus précis de l'étendue de la zone de combustion, de la chaleur dégagée par la combustion distribuée des gouttes et de la distribution en taille des résidus. Nos efforts ont porté sur la modélisation des échanges entre la phase gazeuse et cette phase dispersée composée de gouttes de nature et de taille très diverses. Le paramètre taille pilotant la dynamique du spray et le couplage avec le gaz, le suivi précis des changements de taille est un enjeu majeur.Dans cette contribution, nous avons choisi une approche cinétique pour la description des sprays polydisperses. L'équation cinétique de Williams-Boltzmann utilisée pour suivre l'évolution des propriétés du spray est résolue par une approche eulérienne. Les méthodes Multi-Fluide (MF) traitent naturellement les changements de taille tels que l'évaporation et la coalescence. Ces méthodes reposent sur une intégration continue de la variable taille sur des intervalles fixes appelés sections sur lesquels nous pouvons dériver des systèmes d'équations de conservation. Chaque système est vu comme un fluide qui est en couplage fort avec la phase gazeuse via des termes sources.Nous avons travaillé sur une méthode MF à deux moments en taille basée sur une famille de fonctions de forme polynomiale pour reconstruire la distribution en taille au sein des sections. Cette approche d'ordre deux en temps et en espace s'avère performante car elle décrit avec précision l'évolution de la distribution avec un nombre modéré de sections. Un travail original a été mené afin d'étendre l'approche MF à des gouttes bicomposants. Cette méthode ouvre la voie à des modèles de combustion des gouttes d'aluminium plus représentatifs. Dans le contexte des simulations instationnaires, nous avons porté une attention particulière à l'emploi d'une stratégie numérique robuste et précise pour le couplage entre les phases modélisées par une approche Euler-Euler. Nous montrons qu'une méthode de splitting séparant le traitement du transport des phases gazeuse/dispersée de celui des termes sources est particulièrement adaptée pour la résolution d'un problème multi-échelle spatial et temporel. Dans la mesure où les conditions de réalisabilité sur les moments en taille des méthodes MF ne sont pas garanties avec des méthodes d'intégration traditionnelles, nous avons développé des schémas innovants pour l'intégration des termes sources. Les travaux proposés dans cette contribution répond à deux exigences : 1- un ratio coût/précision attractif pour des simulations industrielles 2- une facilité d'implémentation des méthodes et une modularité assurant la pérennisation des codes industriels. Ces développements ont d'abord été vérifiés à l'aide d'un code ad hoc ; des cas test d'étude d'acoustique diphasique linéaire ont notamment souligné la pertinence de la technique de splitting pour restituer avec précision les interactions spray-acoustique. Les nouvelles méthodes ont ensuite été implémentées et validées au sein du code multi-physique CEDRE développé à l'ONERA. Des calculs de propulsion solide sur des configurations moteur réalistes ont finalement mis en évidence le niveau de maturité atteint par les méthodes eulériennes pour décrire avec fidélité la dynamique des sprays polydisperses. Les résultats de ces simulations ont mis en avant la sensibilité des niveaux d'instabilités en fonction de la distribution en taille des gouttes d'aluminium et des résidus<br>The addition of a significant mass fraction of aluminum particle in the propellant of Solid Rocket Motors improves performance through an increase of the temperature in the combustion chamber. The distributed combustion of aluminum droplets in a portion of the chamber yields a massive amount of disperse aluminum oxide residues with a large size spectrum, called a polydisperse spray, in the entire volume. The spray can have a significant impact on the motor behavior and in particular on the onset/damping of instability. When dealing with aeroacoustical and thermoacoustical instabilities, the faithful prediction of the interactions between the gaseous phase and the spray is a determining step for understanding the physical mechanisms and for future solid rocket motor optimization. In such a harsh environment, experimental measurements have a hard time providing detailed explanation of the physical mechanisms and one has to resort to numerical simulation. For such a purpose, the distributed combustion zone and thermal profile therein, the heat generated by the combustion of the dispersed droplets and the large size distribution of the aluminum oxide residues and its coupling with he gaseous phase hydrodynamic and acoustic fields have to be accurately reproduced through a proper level of modeling and a high fidelity simulation including a precise resolution of size polydispersity, which is a key parameter.In this contribution, we choose a kinetic approach for the description of polydisperse sprays. The Williams-Boltzmann Equation is used to model the disperse phase and we derive a fully Eulerian approach through moment methods. The Multi-Fluid (MF) methods naturally treat droplet size evolution through phenomena such as evaporation and coalescence. These methods rely on the conservation of size moments on fixed intervals called sections and yield systems of conservation laws for a set of "fluids" of droplet of various sizes, which is strongly coupled with the gas phase via source terms. We derive a new optimal and flexible Two Size Moment MF method based on a family of polynomial reconstruction functions to describe the size distribution in the sections, which is second order accurate and particularly efficient at describing accurately the evolution of the size distribution with a moderate number of sections. An original work is also conducted in order to extend this approach to two-component droplets. For size moment MF methods, realizability of the moments is a crucial issue. Thus, we have developed innovative schemes for integrating source terms in moment conservation equations describing transport in phase space. This method enables the use of more representative aluminum droplet combustion models, and leads to more advanced studies of the distributed combustion zone. Moreover, for unsteady two-phase flow simulations, we have developed a robust and accurate coupling strategy between phases that are modeled by a fully Eulerian approach based on operator splitting in order to treat such spatial and temporal very multi-scale problems with reasonable computational time. All the proposed developments have been carried out following two criteria : 1- an attractive cost/accuracy ratio for industrial simulations in the context of high fidelity simulations 2- a preservation of industrial code legacy. Verification of the models and methods have been conducted first using an in-house reseach code and then in the context of a two-phase acoustic study thus emphasizing the relevance of the splitting technique to capture accurately spray-acoustic interactions
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Al-obaidi, Hisham Kadhim Hashim. "Optimization of Drug Carrier Interactions in Spray Dried Solid Dispersions." Thesis, University College London (University of London), 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498574.
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Kuhnke, Dominik [Verfasser]. "Spray/Wall-Interaction Modelling by Dimensionless Data Analysis / Dominik Kuhnke." Aachen : Shaker, 2004. http://d-nb.info/1186574682/34.
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Mühlbauer, Monika. "Modelling wall interactions of a high-pressure, hollow cone spray /." Aachen : Shaker, 2009. http://d-nb.info/998456616/04.
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Li, Tingwen. "Numerical investigation of the gas/spray jet interaction with fluidized beds." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/6049.
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In many industrial fluidized bed reactors, for example fluid catalytic cracking units, coaters and fluid cokers, the reactant feed is introduced into the system in the form of a gas jet or spray for different purposes. A good understanding of the interaction between the feed injection and the bed can lead to improved reactor design and operation. Despite the fact that numerical models and simulations have been used extensively to investigate fluidization processes, still little is known about the interactions of the jet/spray with fluidized beds.
In this thesis, gas jets and liquid spray in several gas-solid systems are numerically studied. The Eulerian-Eulerian multi-fluid model with appropriate closure correlations is employed, and two- and three-dimensional numerical simulations are performed accordingly. The numerical simulations can be divided into two groups: two-phase (gas-solid) and three-phase (gas-liquid-solid) simulations. First, a three-dimensional numerical simulation of a single gas jet injection in a cylindrical bubbling fluidized bed is performed and is compared favorably to available experimental data and empirical correlations. After that, the injection of multiple gas jets into a small bubbling fluidized bed is numerically investigated. The influence of the secondary gas injection on the flow hydrodynamics, as well as interactions between the gas jet and the surrounding gas, solids, bubbles, and other jets is studied numerically, and the mixing of the secondary gas with the bed materials is also analyzed. To study the liquid spray in gas-solid systems, several three-phase systems of the low-flow-rate bottom spray into a flat-based spouted bed with a draft tube (DTSB), an evaporating gas-liquid spray into a uniform gas-solid crossflow, and an evaporative water spray into a hot riser are simulated, respectively. Appropriate models are chosen to describe the interactions between spray droplets and particles, as well as the inter-phase heat and mass transfer. While implementing the models in the numerical code, careful comparison with the available experimental data is performed. General features of the spray are properly predicted, and the interaction of the liquid spray with the gas-solid flows is investigated.
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Berti, Rafael da Cruz Ribeiro. "Interaction of turbulent structures with ethanol sprays in mixture formation processes in a constant-flow chamber." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-19092018-082453/.
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The study in formation and evolution of sprays is essential for developing more detailed physical models and new injection strategies for direct injection internal combustion engines. In the present work, the sprays from a multi-hole injector are evaluated in an effort to characterize the effects of the spray development in a constant surrounding air flow. These interactions are studied in terms of the air turbulence characteristics, the inlet air mass flow and the fuel injection pressure. Ethanol sprays are injected in a constant-flow chamber. The apparatus purpose is to isolate the experiment from the fluid flow properties intrinsic to engine operations, such as instabilities and moving walls. The factors that affects the air-spray interactions were assessed with the air velocity fields in the presence of the ethanol spray. The two-phase particle image velocimetry technique was enhanced to allow measuring in the required experimental conditions. In all conditions, the interaction is based in a pressure gradient formed between the inner and outer regions of the spray. The results indicates a different mechanism when compared to quiescent conditions. The recirculation vortex at the spray border is present only in the initial injection stages. However, the end of injection transient, an instability initiated with the injector needle closing, is still present for these conditions. The interaction mechanism accelerates the velocity distributions towards the spray main boundary. The experiments indicate that the increase of the air mass flow modifies the air penetration velocity but without altering the interaction mechanism characteristics. Higher injection pressures suggests a lower degree of air interaction at the initial instants of the spray development. Turbulent intensity distributions are calculated for the air flow during the injection event. The distributions indicate that the sprays attenuate the turbulent intensity in all conditions, consistent with the observations of the velocity fields. To assess the effects of air turbulence, sets of interchangeable perforated plates are used to limit the integral scales of turbulence. The spectrogram analyses indicate turbulence is reduced not only in the integral scales, but also in all the measured frequency scales. The inlet turbulence integral scales of the air flow have little influence in the spray development. In the turbulence field, the power levels at the end of injection were similar regardless of the inlet turbulence integral scales.<br>O estudo da formação e evolução dos sprays é essencial para o desenvolvimento de modelos físicos mais detalhados e novas estratégias de injeção para motores de combustão interna de injeção direta. No presente trabalho, os sprays de um injetor multi-furos são avaliados em um esforço para caracterizar os efeitos do desenvolvimento do spray em fluxo de ar constante. Estas interações são estudadas em termos de características de turbulência do ar,do fluxo mássico de ar e da pressão de injeção de combustível. Sprays de etanol são injetados em uma câmara de fluxo constante. O objetivo do aparato é isolar o experimento de propriedades do escoamento intrínsecas ao funcionamento de motores de combustão interna, tais como instabilidades e geometrias móveis. Os fatores que afetam as interações de arspray foram avaliados com os campos de velocidade do ar obtidos na presença de spray. A técnica de velocimetria por imagem de partículas de duas fases foi aprimorada para permitir a medição nas condições experimentais. Em todas as condições, a interação é baseada em um diferencial de pressão formado entre as regiões interna e externa do spray. Os resultados indicam um mecanismo diferente quando comparado com condições quiescentes. O vortex formado na fronteira do spray é observado apenas nos estágios iniciais de injeção. No entanto, o transiente de fim de injeção ainda está presente para essas condições. O mecanismo de interação acelera as distribuições de velocidade em direção à fronteira do jato. Os experimentos indicam que o aumento do fluxo de massa de ar modifica a velocidade de penetração do ar, mas sem alterar as características do mecanismo de interação. Distribuições de intensidade turbulenta são calculadas para o fluxo de ar durante o evento de injeção. As distribuições indicam que os sprays atenuam a intensidade turbulenta em todas as condições, consistente com as observações dos campos de velocidade. Para avaliar os efeitos da turbulência do ar, conjuntos de placas perfuradas intercambiáveis são utilizadas para limitar as escalas integrais de turbulência. As análises do espectrograma indicam que a turbulência é reduzida não apenas nas escalas integrais, mas também em todas as escalas de freqüência medidas. Estas escalas integrais de turbulência do fluxo de ar de entrada têm pouca influência no desenvolvimento do spray. No campo de turbulência, os níveis de potência ao final da injeção foram semelhantes, independentemente das escalas integrais de turbulência de entrada.
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Mühlbauer, Monika [Verfasser]. "Modelling wall interactions of a high-pressure, hollow cone spray / Monika Mühlbauer." Aachen : Shaker, 2009. http://d-nb.info/1161302034/34.
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Choi, Bernard. "Thermal interactions of pulsed laser radiation and cryogen spray cooling with skin." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3025203.
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Kempthorne, Daryl Matthew. "The development of virtual leaf surface models for interactive agrichemical spray applications." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/84525/12/84525%28thesis%29.pdf.
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This project constructed virtual plant leaf surfaces from digitised data sets for use in droplet spray models. Digitisation techniques for obtaining data sets for cotton, chenopodium and wheat leaves are discussed and novel algorithms for the reconstruction of the leaves from these three plant species are developed. The reconstructed leaf surfaces are included into agricultural droplet spray models to investigate the effect of the nozzle and spray formulation combination on the proportion of spray retained by the plant. A numerical study of the post-impaction motion of large droplets that have formed on the leaf surface is also considered.
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Börnhorst, Marion [Verfasser]. "Urea-Water Sprays in NOx Emission Control Systems: Interaction with Solid Walls and Deposit Formation / Marion Börnhorst." Düren : Shaker, 2020. http://d-nb.info/1215461917/34.
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Stratmann, Jochen. "Droplet wall and spray wall interaction at increased ambient pressure and wall temperature." Aachen Shaker, 2009. http://d-nb.info/995684472/04.
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Gardiner, A. J. "The mathematical modelling of the interaction between sprinkler sprays and the thermally buoyant layers of gases from fires." Thesis, London South Bank University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234279.
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Dressler, Daniel. "An experimental investigation of Newtonian and non-Newtonian spray interaction with a moving surface." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/71.
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As a logical extension of previous work conducted into viscoelastic atomization, initially motivated by the need to improve spray coating transfer efficiencies, an experimental investigation into the spray-surface interaction for a number of Newtonian and non-Newtonian substitute test liquids is presented. Three model elastic liquids of varying polymer molecular weight and three inelastic liquids of varying shear viscosity were sprayed upon a moving surface to isolate the effect of elasticity and shear viscosity, respectively, on spray impaction behavior. In addition, two liquids exhibiting shear thinning behavior and an industrial top of rail liquid friction modifier, KELTRACK, for use in the railroad industry, were included in the spray tests. High-speed photography was used to examine the impingement of these liquids on the surface.
Ligaments, formed as a consequence of a liquid’s viscoelasticity, were observed impacting the surface for 300K PEO, 1000K PEO, and KELTRACK. These ligaments were broadly classified into four groups, based on their structure. Splashing of elastic liquid ligaments and droplets led to filamentary structures being expelled from the droplet periphery, which were then carried away by the atomizing air jet, leading to reductions in transfer efficiency. The effect of increasing elasticity amongst the three varying molecular weight elastic solutions was shown to increase the splash threshold; a similar effect was noted with increasing shear viscosity.
Attempts were made at quantifying a critical splash-deposition limit for all test liquids however due to imaging system limitations, no quantitative conclusions could be made.
For KELTRACK, both droplets and ligaments spread and deposited on the rail surface upon impact, with no observed splash or rebound. Splash was only noted when droplets impinged directly on a previously deposited liquid film and even then, splashing was well contained. Thus, KELTRACK’s current rheological formulation proved to be very effective in ensuring high coating transfer efficiencies.
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Desflots, Melicie. "Environmental and Internal Controls of Tropical Cyclones Intensity Change." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/120.
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Tropical cyclone (TC) intensity change is governed by internal dynamics (e.g. eyewall contraction, eyewall replacement cycles, interactions of the inner-core with the rainbands) and environmental conditions (e.g. vertical wind shear, moisture distribution, and surface properties). This study aims to gain a better understanding of the physical mechanisms responsible for TC intensity changes with a particular focus to those related to the vertical wind shear and surface properties by using high resolution, full physics numerical simulations. First, the effects of the vertical wind shear on a rapidly intensifying storm and its subsequent weakening are examined. Second, a fully coupled atmosphere-wave-ocean model with a sea spray parameterization is used to study the impact of sea spray on the hurricane boundary layer. The coupled model consists of three components: the high resolution, non-hydrostatic, fifth generation Pennsylvania State University-NCAR mesoscale model (MM5), the NOAA/NCEPWAVEWATCH III (WW3) ocean surface wave model, and theWHOI threedimensional upper ocean circulation model (3DPWP). Sea spray parameterizations were developed at NOAA/ESRL and modified by the author to be introduced in uncoupled and coupled simulations. The model simulations are conducted in both uncoupled and coupled modes to isolate various physical processes influencing TC intensity. The very high-resolutionMM5 simulation of Hurricane Lili (at 0.5 km grid resolution) showed a rapid intensification associated with a contracting eyewall. Changes in both the magnitude and the direction of the vertical wind shear associated with an approaching upper-tropospheric trough were responsible for the weakening of the storm before landfall. Hurricane Lili weakened in a 5-10 m/s vertical wind shear environment. The simulated storm experienced wind shear direction normal to the storm motion, which produced a strong wavenumber one rainfall asymmetry in the downshear-left quadrant of the storm. The rainfall asymmetry was confirmed by various observations from the TRMM satellite and the WSR-88D ground radar in the coastal region. The increasing vertical wind shear induced a vertical tilt of the vortex with a time lag of about 5-6 hours after the wavenumber one rainfall asymmetry was first observed in the model simulation. Other key factors controlling intensity and intensity change in tropical cyclones are the air-sea fluxes. Accurate measurement and parameterization of air-sea fluxes under hurricane conditions are challenging. Although recent studies have shown that the momentum exchange coefficient levels off at high wind speed, little is known about the high wind behavior of the exchange coefficient for enthalpy flux. One of the largest uncertainties is the potential impact of sea spray. The current sea spray parameterizations are closely tied to wind speed and tend to overestimate the mediated heat fluxes by sea spray in the hurricane boundary layer. The sea spray generation depends not only on the wind speed but also on the variable wave state. A new spray parameterization based on the surface wave energy dissipation is introduced in the coupled model. In the coupled simulations, the wave energy dissipation is used to quantify the amount of wave breaking related to the generation of sea spray. The spray parameterization coupled to the waves may be an improvement compared to sea spray parameterizations that depends on wind speed only.
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Khan, Muhammad. "RANS and LES of multi-hole sprays for the mixture formation in piston engines." Phd thesis, Ecole Centrale de Lyon, 2014. http://tel.archives-ouvertes.fr/tel-01002111.
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Cette thèse porte sur la simulation des jets de gouttes générés par des pulvérisateurs essence haute pression, pulvérisateurs qui sont un point clef des systèmes de combustion automobile de la présente et future génération devant diminuer les émissions de CO2 et de polluants. Dans un premier temps les jets de gouttes (" sprays ") sont simulés par simulation moyennée. Les résultats de simulation d'un jet donnant des résultats en moyenne satisfaisant, l'interaction de jets en injecteurs multi-trous est alors simulée. Les résultats sont cohérents par rapport aux mesures d'entraînement d'air. La simulation permettant d'avoir accès au champ complet 3D, le mécanisme d'interaction jet à jet et de développement instationnaire du spray est décrit en détail. La formation d'un mouvement descendant au centre du spray et celle d'un point d'arrêt central sont trouvés. Finalement, Ces résultats sont étendus au cas surchauffé, cas où la pression dans la chambre est inférieure à la pression de vapeur saturante. Un modèle simple semi-empirique est proposé pour tenir compte de la modification des conditions proches de la buse d'injection. Le modèle prédit correctement les tendances des variations de paramètres et capture la forme générale du spray qui se referme sur lui-même. La seconde grande partie est consacrée au développement d'un modèle de spray par l'approche des grandes échelles (SGE), limité ici aux cas non évaporant. Il comprend la modélisation de sous-maille de la dispersion turbulente, des collisions-coalescence et des termes d'échange de quantité de mouvement de sous-maille. L'effet du choix du modèle de sous-maille pour la viscosité turbulente de sous-maille est montré, le choix retenu étant le modèle de Smagorinski dynamique. Afin d'améliorer la représentativité cruciale des conditions d'injections, un couplage faible est réalisé à partir de résultats de simulations existantes de l'écoulement interne aux buses. Les fonctions densité de probabilité simple et jointes extraits des résultats de simulations sont validés par rapport aux mesures PDA en situation pseudo-stationnaire et la pénétration liquide et la forme du spray est comparée aux visualisations par ombroscopie. Enfin, différentes zones caractéristiques sont identifiées et des longueurs sont notées pour les cas d'injection à 100 et 200bar.
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Stratmann, Jochen [Verfasser]. "Droplet-Wall and Spray-Wall Interaction at Increased Ambient Pressure and Wall Temperature / Jochen Stratmann." Aachen : Shaker, 2009. http://d-nb.info/1159832323/34.
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Emre, Oguz. "Modeling of spray polydispersion with two-way turbulent interactions for high pressure direct injection in engines." Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0029/document.
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La simulation des écoulements diphasiques rencontrés dans les moteurs à combustion interne (MCI) est de grande importance pour la prédiction de la performance des moteurs et des émissions polluantes. L’injection directe du carburant liquide à l’intérieur de la chambre de combustion génère loin de l’injecteur un brouillard de gouttes polydisperses, communément appelé spray. Du point de vue de la modélisation, l’émergence des méthodes Eulériennes pour la description du spray est considérée prometteuse par la communauté scientifique. De plus, la prise en compte de la distribution en taille des gouttes par les approches Eulériennes, de manière peu coûteuse en temps de calcul, n’est plus considérée comme un verrou depuis le développement de la méthode Eulerian Multi Size Moment (EMSM). Afin d’envisager la simulation de configurations réalistes de MCI, ce travail de thèse propose de modéliser les interactions turbulentes two-way entre le spray polydisperse évaporant et la phase gazeuse environnante par la méthode EMSM. Dans le contexte du formalisme Arbitrary Lagrangian Eulerian (ALE) dédiée au traitement du maillage mobile, les termes sources présents dans le modèle diphasique sont traités séparément des autres contributions. Le système d’équations est fermé à l’aide d’une technique de reconstruction par maximisation d’entropie (ME), originellement introduite pour EMSM. Une nouvelle stratégie de résolution a été développée pour garantir la stabilité numérique aux échelles de temps très rapides introduites par les transferts de masse, quantité de mouvement et énergie, tout en respectant la condition de réalisabilité associée à la préservation de l’espace des moments d’ordre ´élevé. A l’aide des simulations académiques, la stabilité et la précision de la méthode ont été étudiées aussi bien pour des lois d’évaporation constantes que dépendantes du temps. Tous ces développements ont été intégrés dans le code industriel IFP-C3D dédié aux écoulements compressibles et réactifs. Dans le contexte de la simulation en 2-D de l’injection directe, les résultats se sont avérés très encourageants comme en témoignent les comparaisons qualitatives et quantitatives de la méthode Eulerienne à la simulation Lagrangienne de référence des gouttes. De plus, les simulations en 3-D effectuées dans une configuration typique de chambre de combustion et des conditions d’injection réalistes ont donné lieu à des résultats qualitativement très satisfaisants. Afin de prendre en compte la modélisation de la turbulence, une extension moyennée, au sens de Reynolds, des équations du modèle diphasique two-way est dérivée, un soin particulier étant apporté aux fermetures des corrélations turbulentes. La répartition de l’énergie dans le spray ainsi que les interactions turbulentes entre les phases ont été étudiées dans des cas tests homogènes. Ces derniers donnent un aperçu intéressant sur la physique sous-jacente dans les MCI. Cette nouvelle approche RANS diphasique est maintenant prête à être employée pour les simulations d’application de MCI<br>The ability to simulate two-phase flows is of crucial importance for the prediction of internal combustion engine (ICE) performance and pollutant emissions. The direct injection of the liquid fuel inside the combustion chamber generates a cloud of polydisperse droplets, called spray, far downstream of the injector. From the modeling point of view, the emergence of Eulerian techniques for the spray description is considered promising by the scientific community. Moreover, the bottleneck issue for Eulerian methods of capturing the droplet size distribution with a reasonable computational cost, has been successfully tackled through the development of Eulerian Multi Size Moment (EMSM) method. Towards realistic ICE applications, the present PhD work addresses the modeling of two-way turbulent interactions between the polydisperse spray and its surrounding gas-phase through EMSM method. Following to the moving mesh formalism ArbitraryLagrangian Eulerian (ALE), the source terms arising in the two-phase model have been treated separately from other contributions. The equation system is closed through the maximum entropy (ME) reconstruction technique originally introduced for EMSM. A new resolution strategy is developed in order to guarantee the numerical stability under veryfast time scales related to mass, momentum and energy transfers, while preserving the realizability condition associated to the set of high order moments. From the academic point of view, both the accuracy and the stability have been deeply investigated under both constant and time dependent evaporation laws. All these developments have beenintegrated in the industrial software IFP-C3D dedicated to compressible reactive flows. In the context of 2-D injection simulations, very encouraging quantitative and qualitative results have been obtained as compared to the reference Lagrangian simulation of droplets. Moreover, simulations conducted under a typical 3-D configuration of a combustion chamber and realistic injection conditions have given rise to fruitful achievements. Within the framework of industrial turbulence modeling, a Reynolds averaged (RA) extension of the two-way coupling equations is derived, providing appropriate closures for turbulent correlations. The correct energy partitions inside the spray and turbulent interactions between phases have been demonstrated through homogeneous test-cases. The latter cases gave also some significant insights on underlying physics in ICE. This new RA approach is now ready for ICE application simulations
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PITTIA, PAOLA. "Physical state of sugar matrices and aroma-sugars interactions at nanoscale." Doctoral thesis, Università degli Studi di Trieste, 2016. http://hdl.handle.net/11368/2908096.
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Haglund, Charlotte. "Social interaction and identification among adolescents in multilingual suburban Sweden : a study of institutional order and sociocultural change /." Stockholm : Centre for Research on Bilingualism, Stockholm University, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-457.
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Mueller, James A. "On the transfer of momentum, heat and mass at the air-sea and air-sea spray interfaces." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 190 p, 2009. http://proquest.umi.com/pqdweb?did=1833621151&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Mariani, Valerio <1991>. "Development of numerical methodologies to predict the liquid fuel sprays - wall interaction to optimize the mixing process of direct injection spark ignition engines." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/10107/1/Tesi_dottorato-Valerio_Mariani.pdf.
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Nowadays the development of new Internal Combustion Engines is mainly driven by the need to reduce tailpipe emissions of pollutants, Green-House Gases and avoid the fossil fuels wasting. The design of dimension and shape of the combustion chamber together with the implementation of different injection strategies e.g., injection timing, spray targeting, higher injection pressure, play a key role in the accomplishment of the aforementioned targets. As far as the match between the fuel injection and evaporation and the combustion chamber shape is concerned, the assessment of the interaction between the liquid fuel spray and the engine walls in gasoline direct injection engines is crucial. The use of numerical simulations is an acknowledged technique to support the study of new technological solutions such as the design of new gasoline blends and of tailored injection strategies to pursue the target mixture formation. The current simulation framework lacks a well-defined best practice for the liquid fuel spray interaction simulation, which is a complex multi-physics problem. This thesis deals with the development of robust methodologies to approach the numerical simulation of the liquid fuel spray interaction with walls and lubricants. The accomplishment of this task was divided into three tasks: i) setup and validation of spray-wall impingement three-dimensional CFD spray simulations; ii) development of a one-dimensional model describing the liquid fuel – lubricant oil interaction; iii) development of a machine learning based algorithm aimed to define which mixture of known pure components mimics the physical behaviour of the real gasoline for the simulation of the liquid fuel spray interaction.
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Hartell, Ann. "Sprawl and Commuting: Exploring New Measures of United States Metro Regions." WU Vienna University of Economics and Business, 2015. http://epub.wu.ac.at/6095/1/sre%2Ddisc%2D2015_07.pdf.
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The degree of connectivity and proximity that results from the configuration of land uses and associated transport networks is an important concept in much of the transportation research agenda. A substantial body of work has developed around the idea that compact, mixed-use
development with multimodal transport options will shape travel behavior, increasing the use of transit, walking, and cycling for routine travel. Yet empirical evidence is somewhat mixed. One of the reasons for this uncertainty is the difficulty of defining and measuring sprawl in a
meaningful way for use in quantitative analyses, rather than using regionally idiosyncratic or mono-dimensional definitions of sprawl. A recently released national dataset measuring multiple dimensions of urban form offers an opportunity to explore the relationship between transportation and sprawl.
This study uses a series of spatial regressions to model effects on the share of a county's workers who commute by driving alone. The results for income are found to be robust across various model specifications, confirming the well-established, positive relationship between income and d
riving to work. The results for the Street Accessibility
Factor suggest characteristics of the street network are
related to the choice to commute by driving alone, with more compact street networks and greater connectivity associated with reduced driving alone. The Land Use Mixing Factor has little power in explaining travel behavior, despite its intuitive appeal as the land use component of the commute mode decision.<br>Series: SRE - Discussion Papers
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Peraza, Ávila Jesús Enrique. "Experimental study of the diesel spray behavior during the jet-wall interaction at high pressure and high temperature conditions." Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/149389.
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[EN] The potential of diesel engines in terms of robustness, efficiency and energy density has made them widely used as power generators and propulsion systems. Specifically, fuel atomization, vaporization and air-fuel mixing, have a fundamental effect on the combustion process, and consequently, a direct impact on pollutant formation, fuel consumption and noise emission. Since the combustion chamber has a limited space respect to the spray penetration, wall impingement is considered to be a common event in direct injection diesel engines, having a relevant influence in the spray evolution and its interaction with both surrounding air and solid walls. This makes of spray-wall interaction an important factor for the combustion process that is still hardly understood.
At cold-start conditions, the low in-chamber pressures and temperatures promote the deposition of fuel in the piston wall, which leads to a boost in the formation of unburned hydrocarbons. Additionally, modern design trends such as the increment of rail pressures in injection systems and the progressive reduction of the engine displacement, favor the emergence of spray collision onto the walls. In spite of the evident relevance of the comprehension of this phenomenon and the efforts of engine researchers to reach it, the transient nature of injection process, its small time scales and the complexity of the physical phenomena that take place in the vicinity of the wall, make challenging the direct observation of this spray-wall interaction. Even though computational tools have proven to be priceless in this field of study, the need for reliable experimental data for the development of those predictive models is present.
This thesis is aimed to shed light on the fundamental characteristics of spray-wall interaction (SWI) at diesel-like chamber conditions. A flat wall was set at different impingement distances and angles respect to the spray. In this way, two different kinds of experimental investigations on colliding sprays were carried out: A transparent quartz wall was employed into the chamber to, in isolation, analyze the macroscopic characteristics of the spray at both evaporative inert and reactive conditions, which have been observed laterally and through the wall, thanks to the use of a high-pressure and high-temperature vessel with optical accesses. This same test rig was used in the second kind of experiments, where instead of the quartz plate, a stainless steel wall was used to capture the effect of the operating conditions on the heat flux between the wall and the spray during the injection-combustion events and to determine how spray and flame evolution are affected by realistic heat transfer situations. This wall was instrumented to control its initial in-chamber surface temperature and to measure its variation with time by using high-speed thermocouples. Tests at free-jet conditions were also performed in order to provide a solid comparative base for those experiments.<br>[ES] El potencial de los motores diesel en términos de robustez, eficiencia y la densidad de energía los ha hecho ser ampliamente usados como generadores de energía y sistemas propulsivos. Específicamente, la atomización de combustible, vaporización y mezcla de aire y combustible tienen un efecto fundamental en el proceso de combustión y, en consecuencia, un impacto directo en la formación de emisiones contaminantes, consumo de combustible y generación de ruido. Dado que la cámara de combustión tiene un espacio limitado con respecto la capacidad de penetración del chorro, el impacto de la pared se considera bastante común en motores de inyección directa diésel, que tienen una influencia relevante en la evolución del chorro y su interacción con el aire circundante y las paredes sólidas. Esto hace de interacción chorro-pared, un factor importante para el proceso de combustión que aún es dificilmente comprendido.
En condiciones de arranque en frío, las bajas presiones y temperaturas en la cámara promueven la deposición de combustible en la pared del pistón, lo que conduce a un aumento en los niveles de formación de hidrocarburos no quemados. Además, las tendencias modernas de diseño como el incremento de las presiones de rail en los sistemas de inyección y la progresiva reducción en la cilindrada de los motores, favorecen la aparición de colisiones entre chorro y pared. A pesar de la evidente importancia en la comprensión de este fenómeno y los esfuerzos de los investigadores para alcanzarla, la transitoria naturaleza del proceso de inyección, sus pequeñas escalas de temporales y la complejidad de los fenómenos físicos que tienen lugar en las proximidades de la pared, hacen que la observación directa de esta interacción chorro-pared sea un desafío. Aunque las herramientas computacionales han demostrado ser invaluables en este campo de estudio, la necesidad de datos experimentales confiables para el desarrollo de esos modelos predictivos está muy presente.
Esta tesis tiene como objetivo arrojar luz sobre las características fundamentales de la interacción chorro-pared (SWI por sus siglas en inglés) en condiciones de cámara similares a las de un motor diesel. Se colocó una pared plana a diferentes distancias de impacto y ángulos con respecto al jet. De esta manera, dos tipos diferentes de investigaciones experimentales sobre chorros en colisión se llevaron a cabo: se empleó una pared de cuarzo transparente en la cámara para, de forma aislada, analizar las características macroscópicas del chorro en condiciones evaporativas inertes y reactivas, que pueden observarse lateralmente y a través de la pared, gracias al uso de una instalación de alta presión y alta temperatura ópticamente accesible. Esta misma instalación se utilizó en el segundo tipo de experimentos en los que se introdujo una pared de acero inoxidable para capturar adicionalmente el efecto de las condiciones de operación en el flujo de calor entre ésta y el chorro durante los eventos de inyección y combustión y para determinar cómo la evolución del chorro y la llama son afectadas por una situación realista de transferencia de calor. Esta pared fue instrumentada para controlar la temperatura inicial de su superficie expuesta a la cámara y medir su variación con el tiempo, utilizando termopares de alta velocidad. Ensayos en condiciones de chorro libre también se realizaron para proporcionar una base comparativa sólida para esos experimentos.<br>[CA] El potencial dels motors dièsel en termes de robustesa, eficiència i la densitat d'energia els ha fet ser àmpliament usats com a generadors d'energia i sistemes propulsius. Específicament, l'atomització de combustible, vaporització i barreja d'aire i combustible tenen un efecte fonamental en el procés de combustió i, en conseqüència, un impacte directe en la formació d'emissions contaminants, consum de combustible i generació de soroll. Atès que la cambra de combustió té un espai limitat pel que fa la capacitat de penetració de l'raig, l'impacte de la paret es considera bastant comú en motors d'injecció directa dièsel, que tenen una influència rellevant en l'evolució del doll i la seva interacció amb el aire circumdant i les parets sòlides. Això fa d'interacció doll-paret, un factor important per al procés de combustió que encara és difícilment comprès.
En condicions d'arrencada en fred, les baixes pressions i temperatures a la cambra promouen la deposició de combustible a la paret del pistó, el que condueix a un augment en els nivells de formació d'hidrocarburs no cremats. A més, les tendències modernes de disseny com l'increment de les pressions de rail en els sistemes d'injecció i la progressiva reducció en la cilindrada dels motors, afavoreixen l'aparició de col·lisions entre el doll i la paret. Tot i l'evident importància en la comprensió d'aquest fenomen i els esforços dels investigadors per aconseguir-la, la transitòria naturalesa de l'procés d'injecció, les seves petites escales de temporals i la complexitat dels fenòmens físics que tenen lloc en les proximitats de la paret , fan que l'observació directa d'aquesta interacció doll-paret siga un desafiament. Tot i que les eines computacionals han demostrat ser invaluables en aquest camp d'estudi, la necessitat de dades experimentals fiables per al desenvolupament d'aquests models predictius està molt present.
Aquesta tesi té com a objectiu donar llum sobre les característiques fonamentals de la interacció doll-paret (SWI per les seues sigles en anglès) en condicions de cambra similars a les d'un motor dièsel. Es va col·locar una paret plana a diferents distàncies d'impacte i angles pel que fa al jet. D'aquesta manera, dos tipus diferents d'investigacions experimentals sobre dolls en col·lisió es van dur a terme: es va emprar una paret de quars transparent a la cambra per, de forma aïllada, analitzar les característiques macroscòpiques del doll en condicions evaporació inerts i reactives, que poden observar lateralment i a través de la paret, gràcies a l'ús d'una instal·lació d'alta pressió i alta temperatura òpticament accessible. Aquesta mateixa instal·lació es va utilitzar en el segon tipus d'experiments en els quals es va introduir una paret d'acer inoxidable per capturar addicionalment l'efecte de les condicions d'operació en el flux de calor entre aquesta i el dull durant els esdeveniments d'injecció i combustió i per determinar com l'evolució del doll i la flama són afectades per una situació realista de transferència de calor. Aquesta paret va ser instrumentada per controlar la temperatura inicial de la seua superfície exposada a la càmera i mesurar la seua variació amb el temps, utilitzant termoparells d'alta velocitat. Assajos en condicions de doll lliure també es van realitzar per proporcionar una base comparativa sòlida per a aquests experiments.<br>Peraza Ávila, JE. (2020). Experimental study of the diesel spray behavior during the jet-wall interaction at high pressure and high temperature conditions [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149389<br>TESIS
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Ries, Klaus [Verfasser]. "Accessing spoken interaction through dialogue processing / Klaus Ries." Karlsruhe : KIT-Bibliothek, 2001. http://d-nb.info/1013827791/34.
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Friedman, Jacob A. "Investigating the interaction of an annular air jet with a spray flame using phase-Doppler interferometry and laser-induced fluorescence." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0006/NQ30609.pdf.
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Mariani, Valerio. "Validazione di metodologie di simulazione dell’impatto a parete di spray di combustibile iniettati ad alta pressione." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Il presente lavoro di tesi, svolto in collaborazione con una azienda del settore automotive, tratta lo studio di impatto di sprays combustibili su pareti calde adottando un approccio numerico CFD-3D. Viene effettuata la validazione di alcuni tra i più utilizzati modelli di interazione goccia-parete implementati nel software commerciale STAR-CD. Lo scopo principale del lavoro svolto è quello di indirizzare il lettore verso una corretta implementazione della simulazione di uno spray impattante, comprendere pregi e limiti dei modelli applicati e fornire dei criteri per effettuare la scelta tra uno di essi in funzione di condizioni di interesse motoristico.
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Eduardo, Rodrigo. "Exploring Tumor Macrophage Interaction in Anaplastic Thyroid Cancer." Master's thesis, Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica António Xavier, 2019. http://hdl.handle.net/10362/130111.
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"Anaplastic thyroid cancer (ATC) is the most aggressive form of thyroid cancer, with very high mortality rate. Tumor-associated macrophages (TAMs) can represent up to 70% of ATC’s tumor mass, making them an interesting target for novel therapies.
In this thesis, the aim was to further understand the crosstalk between ATC and TAMs. To achieve that, cell surface proteomics of two ATC cell lines (C3948 and T235), in mono- or co-culture with THP-1-derived macrophage-like cells, was performed. The protein Spry-4, an inhibitor of the MAPK-ERK pathway, was found to be downregulated in C3948 cells upon co-culture. Spry-4 protein levels were further evaluated by Western blot; only T235 in co-culture showed a trend for downregulation, although without statistical significance.(...)"<br>N/A
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Blei, Stefan [Verfasser]. "On the Interaction of non-Uniform Particles during the Spray Drying Process : Experiments and Modelling with the Euler-Lagrange Approach / Stefan Blei." Aachen : Shaker, 2006. http://d-nb.info/1186587172/34.
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Björk-Willén, Polly. "Lära och leka med flera språk : socialt samspel i flerspråkig förskola /." Linköping : Tema Barn, Linköpings universitet, 2006. http://www.bibl.liu.se/liupubl/disp/disp2006/arts376s.pdf.
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Hohmann, Sandra. "Mensch - Maschine - Interface : Studien zu einer Theorie der Mensch-Computer-Interaktion / Men - Machine - Interface : Studies towards a theory of human-computer-interaction." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=968823734.
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Lemetayer, Julien. "Etude par PIV par fluorescence de l’interaction d’un spray avec un écoulement gazeux en aérodynamique contrôlée : application à l’injection directe essence." Thesis, Rouen, INSA, 2016. http://www.theses.fr/2016ISAM0023/document.
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De nombreux procédés actuels mettent en jeu des écoulements diphasiques (sprays agricoles, pharmaceutiques, peinture...). Néanmoins, la connaissance des mécanismes régissant les interactions entre les phases (entraînement, modification des trajectoires des particules, transfert d'énergie...) est encore incomplète, notamment lors de l'injection directe essence, qui représente le cadre de cette étude. Dans cette étude expérimentale, les dynamiques instantanées des deux phases sont étudiées dans un plan pour mettre en évidence les interactions aérodynamiques entre les phases. Pour ce faire, un diagnostic de FPIV diphasique, utilisant un colorant fluorescent pour chaque phase, est développé afin d'acquérir simultanément des images séparées de chaque phase sur deux caméras indépendantes. Ainsi, les vitesses instantanées et simultanées des deux phases sont mesurées sans recourir à un prétraitement des images. Dans un premier temps, ce diagnostic optique est appliqué à la caractérisation d'une injection dans un gaz au repos. L'injection du spray met en mouvement le gaz par le biais d'un transfert de quantité de mouvement du spray vers le gaz. La dispersion des gouttes du spray et le mélange des deux phases qui résultent de ces transferts d'énergie cinétique dépendent du type de spray et également de la pression d'injection. Dans un second temps, ces interactions sont étudiées dans un moteur monocylindre transparent. La comparaison entre les fonctionnements avec et sans injection indique un impact notable de la présence du spray sur l'aérodynamique interne par le développement de nouvelles structures et la modification des caractéristiques du tumble. L'aérodynamique interne du moteur modifie également le développement du spray en comparaison de l'injection dans un gaz au repos<br>Two-phase flows are involved in numerous actual industrial processes (agriculture, pharmacy, painting...). However, the complex interactions between phases (entrainment, particle trajectory modification, energy transfer...) are not well understood, especially for the gasoline direct injection, which represents the context of this study. For this experimental study, instantaneous dynamics of both phases are studied in a plan to highlight the aerodynamic interactions between phases. To achieve that, a two-phase FPIV diagnostic, based on using a fluorescent dye for each phase, is developed to simultaneously acquire separated images of each phase on two independent cameras. Instantaneous and simultaneous velocities of both phases are measured without any image pre-processing. Firstly, this optical diagnostic is applied to the characterisation of a spray injection in a gas at rest. The spray drags the gas by a momentum transfer from spray to gas. The spray droplet dispersion and the mixture between the two phases, which result from this kinetic energy transfer, depend on the spray topology and the injection pressure. Then, these interactions are studied in a transparent monocylinder engine. The comparison between cycles with and without injection reveals a significant impact of the spray presence on the internal aerodynamic through the development of new structures and the modification of tumble characteristics. The internal aerodynamic also modifies the spray development in comparison to the injection in a gas at rest
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Patel, Nayan V. "Simulation of Hydrodynamic Fragmentation from a Fundamental and an Engineering Perspective." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/16225.
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Liquid fragmentation phenomenon is explored from both a fundamental (fully resolved) and an engineering (modeled) perspective. The dual objectives compliment each other by providing an avenue to gain further understanding into fundamental processes of atomization as well as to use the newly acquired knowledge to address practical concerns. A compressible five-equation interface model based on a Roe-type scheme for the simulation of material boundaries between immiscible fluids with arbitrary equation of state is developed and validated. The detailed simulation model accounts for surface-tension, viscous, and body-force effects, in addition to acoustic and convective transport. The material interfaces are considered as diffused zones and a mixture model is given for this transition region. The simulation methodology combines a high-resolution discontinuity capturing method with a low-dissipation central scheme resulting in a hybrid approach for the solution of time- and space-accurate interface problems. Several multi-dimensional test cases are considered over a wide range of physical situations involving capillary, viscosity, and gravity effects with simultaneous presence of large viscosity and density ratios. The model is shown to accurately capture interface dynamics as well as to deal with dynamic appearance and disappearance of material boundaries.
Simulation of atomization processes and its interaction with the flow field in practical devices is the secondary objective of this study. Three modeling requirements are identified to perform Large-Eddy Simulation (LES) of spray combustion in engineering devices. In concurrence with these requirements, LES of an experimental liquid-fueled Lean Direct Injection (LDI) combustor is performed using a subgrid mixing and combustion model. This approach has no adjustable parameters and the entire flow-path through the inlet swirl vanes is resolved. The inclusion of the atomization aspects within LES eliminates the need to specify dispersed-phase size-velocity correlations at the inflow boundary. Kelvin-Helmholtz (or aerodynamic) breakup model by Reitz is adopted for the combustor simulation. Two simulations (with and without breakup) are performed and compared with measurements of Cai et al. Time-averaged velocity prediction comparison for both gas- and liquid-phase with available data show reasonable agreement. The major impact of breakup is on the fuel evaporation in the vicinity of the injector. Further downstream, a wide range of drop sizes are recovered by the breakup simulation and produces similar spray quality as in the no-breakup case.
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Lenain, Luc. "Etudes expérimentales et numériques de la dynamique des vagues et leurs implications pour les échanges océan - atmosphère." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLN033/document.
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Au cours des dernières décennies, les communautés de recherches océanographiques et atmosphérique ont démontrées que pour améliorer notre compréhension du couplage entre l'atmosphère et l'océan, et le paramétrage du flux de masse entre l'océan et l'atmosphère (gaz, aérosols, par exemple) , de moment (pour la génération de vagues et de courants marins) et d'énergie (flux de chaleur et énergie cinétique pour les courants et le processus de mélange près de la surface ) dans les modèles couplés océan-atmosphère, les vagues doivent être prises en compte. La physique du couplage dépend de la cinématique et de la dynamique du champ de vagues, y compris les processus de génération de vagues liées au vent, les interactions non-linéaires, ondes-ondes et la dissipation des vagues, cette dernière étant normalement considérée comme dominée par le déferlement. Nous présentons ici une série d'études expérimentales et numériques, démontrant l'importance du champ de vagues sur les interactions océan - atmosphère<br>Over the last several decades there has been growing recognition from both the traditional oceanographic and atmospheric science communities that to better understand the coupling between the atmosphere and the ocean, and reflect that understanding in improved air-sea fluxes of mass (e.g. gases, aerosols), momentum (e.g. generation of waves and currents) and energy (e.g. heat and kinetic energy for currents and mixing) in coupled ocean-atmosphere models, surface-wave processes must be taken into account. The underlying physics of the coupling depends on the kinematics and dynamics of the wave field, including processes of wind-wave growth, nonlinear wave-wave interactions, wave-current interactions and wave dissipation, with the last normally considered dominated by wave breaking. Here we present a series of experiments, both numerical and field observations, focusing on surface wave effects on air-sea interaction processes
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Marthe, Jimmy. "Élaboration par projection plasma d'un revêtement bicouche d'alumine réfléchissant et diffusant. Contribution à la compréhension des phénomènes interaction rayonnement/matière." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0258/document.
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Ces travaux de thèse sont consacrés à l'élaboration de revêtement réfléchissant et diffusant par projection plasma d'arc soufflé. Par la sélection des paramètres opératoires et le contrôle de la microstructure des revêtements élaborés, la première partie de cette étude présente la mise en forme d'un revêtement bicouche (micro/nano-structuré) d'alumine possédant une réflectance supérieure à 90% sur la gamme UV-Visible. Le transfert nécessaire à la démonstration pour démontrer la faisabilité d'élaboration de pièces de plus grandes dimensions (0.25 m2) a été entrepris. Dans une seconde partie et à partir de l'exploration de la microstructure des revêtements et de leur physicochimie, l'amélioration de la réflectance dans le proche UV par la couche nanostructurée est explicitée d'une part par la nature de la phase cristallographique moins absorbante et d'autre part par la présence en nombre de pores de faibles dimensions. De plus, la caractérisation des propriétés radiatives des revêtements par inversion de l'Equation du Transfert Radiatif a permis d'obtenir des éléments de compréhension des phénomènes d'interaction rayonnement/matière. Enfin, une dernière partie a pour objectif de mettre en place les différents éléments nécessaires à la prédiction des propriétés optiques de revêtements mis en forme par projection plasma. Un modèle tridimensionnel a été proposé pour représenter numériquement la structure de chacune des couches micro- et nanostructurée à partir des analyses microstructurales. Le code de résolution des équations de Maxwell par méthode FDTD (Finite Difference Time Domain) a été validé et de premières simulations ont été réalisées<br>This study deals with the manufacturing of reflecting and scattering coatings by plasma spraying process. By the selection of operating parameters and the control of the coatings microstructure, the first part of this work presents the elaboration of a micro/nanostructured bilayer material in alumina with a reflectance up to 90 % in the near UV-Visible range of wavelength. The feasibility of larger pieces (0.25m2) is demonstrated and the different characterizations for inserting the material in the Laser MegaJoule are performed. In a second part, from characterizations of the microstructure (by SEM, Hg Porosimetry, USAXS) and the chemical composition (DRX, X fluorescence), the improvement of the reflectance in the near-UV thanks to the nanostructured layer is explained, on the one hand, by the less absorbing crystallographic phase and, on the other hand, by the smaller and numerous pores. Moreover, the characterization of the radiation properties by the Radiation Transfer Equation inversion brings new elements for understanding the phenomena during radiation/porous media interaction and to determine the spatial repartition of the scattering radiation. The aim of the last part is to set up the different tools which are necessary to compute simulations of plasma-sprayed coatings optical behavior. From the microstructure analysis, a tridimensional numerical representation of each layer is suggested. The resolution of Maxwell equations is performed by FDTD (Finite Difference Time Domain) method. The model is validated and some first simulations are realized
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Fransén, Nelly. "Studies on a Novel Powder Formulation for Nasal Drug Delivery." Doctoral thesis, Uppsala universitet, Institutionen för farmaci, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9292.
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Nasal administration has potential for the treatment of indications requiring a fast onset of effect or for drugs with low oral bioavailability. Liquid nasal sprays are relatively common, but can be associated with suboptimal absorption from the nasal cavity; this thesis shows that nasal absorption can be significantly enhanced with a dry powder formulation. It was shown that interactive mixtures, consisting of fine drug particles adhered to the surface of mucoadhesive carrier particles, could be created in a particle size suitable for nasal administration. Sodium starch glycolate (SSG), a common tablet excipient, was used as carrier material. In vitro evaluation of the formulation indicated that the mucoadhesion of the carrier was unlikely to be affected by the addition of a drug. The powder formulation did not improve the in vitro transfer of dihydroergotamine across porcine nasal mucosa compared with a liquid formulation; however, the results were associated with methodological shortcomings. The binding of model substances to SSG and three other excipients was evaluated. Ion exchange interactions were for example detected between SSG and cationic drugs, but these interactions were most extensive at low salt concentrations and should unlikely affect in vivo bioavailability at physiological salt concentrations. Absorption of the peptide drug desmopressin from the SSG nasal formulation, from a novel sublingual tablet formulation and from a commercial nasal liquid spray was evaluated in a clinical trial. While no improvement over the liquid spray was seen with the sublingual tablet, plasma concentrations after the nasal powder formulation were three times higher than those after the liquid spray. All formulations were well accepted by the volunteers. The use of currently available mucoadhesive carrier particles in interactive mixtures offers potential for a new method of producing nasal powder formulations that should also be applicable to large scale production.
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Ma, Mingfei. "Are there alternatives to greenbelts? : evidence from a new land-use transport interaction model for Greater Beijing." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/265001.
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Urban greenbelts are considered a key instrument for shaping sustainable urban growth and protecting the environment in a large number of cities in the world. In most cities, there is a widely shared belief that urban greenbelts are beneficial to the natural environment. By contrast, there is little understanding of the underlying economic impacts of greenbelts and other green space configurations in fast growing cities. The unprecedented rate and scale of urbanisation in the emerging economies has brought the role of greenbelts into an even sharper focus. In cities within these fast growing economies, the urban population is expected to double in the coming decades, which means that greenbelts are under great pressures to adapt to the large forthcoming growth. Few existing urban models are capable of addressing the dynamic nature of the urban transformations and predicting the impacts of urban greenbelts in the developing world. This prompts us to develop a new modelling method that is capable of assessing the impacts of different configurations, scales and locations of green spaces. We then use it to examine alternative futures to the greenbelt through a case study of Greater Beijing. The method we developed is a new variant in the land use-transport interaction (LUTI) model family. This model is capable of addressing the non-equilibrium nature of urban land use and transport development and the equilibrium nature of the day-to-day adaptations made by businesses and citizens. This LUTI model aims to answer the following questions: what are the short-term and long-term economic impacts of a greenbelt on a fast growing city? Which alternative green space configuration performs better in terms of economic well-being and travel costs? Where and how much should the greenbelt land be progressively reshaped or released as the city grows? The new LUTI model is calibrated and validated using data collected for 1990, 2000 and 2010 for Greater Beijing, The model is first tested retrospectively through revisiting the past greenbelt policies in Beijing from 1990 to 2010. Then the impacts of different future green space configurations from 2010 to 2030 are predicted and assessed through quantifying economic costs/benefits and travel costs for socio-economic groups. The model results suggest that under rapid transformative urban change, the configuration, scale and location of a greenbelt have a significant impact on a city’s economic efficiency. Such impacts will transcend the greenbelt boundary, and even the boundary of Beijing Municipality, onto the entire city region. A narrow greenbelt launched in the early age of urban expansion could lead to spatial mismatch of residents and jobs. A wide and strictly controlled ring-shaped greenbelt is not the highest performing intervention either, in terms of economic well-being. The green-wedges configuration is a remedial policy that balances the economic efficiency and environmental benefits. Intensive development around metro/rail stations in the designated greenbelt could reduce spatial costs and promote sustainable travel modes. This implies that a careful siting of new development within existing designations of the greenbelt can be beneficial in terms of economic well-being and sustainable transport.
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Cravigan, Luke. "The role of marine biota on the composition and concentration of potential cloud condensation nuclei." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/132173/1/Luke_Cravigan_Thesis.pdf.
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Aerosol-cloud interactions in remote marine environments are poorly represented in atmospheric modelling, which contributes to uncertainties in climate prediction. This work reports on in-situ observations which highlight the importance of biogenic marine aerosols, and their spatial and seasonal variability, to the uncertainty in modelled aerosol-cloud interactions. Measurements were taken during four voyages in the Southern and South Pacific Ocean spanning summer to winter. The observations were used to test the applicability of existing empirical models for the Southern Hemisphere.
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McChesney, Ronald John. "A Three Scale Metropolitan Change Model." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1209393707.
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Samuelfolk, Hugues. "The promotion of Swedish L2 students’ oral proficiency." Thesis, Karlstads universitet, Institutionen för språk, litteratur och interkultur (from 2013), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-72842.
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The purpose of this study has been to examine how Swedish teachers of English encourage the development of students’ oral proficiency in the English language. By interviewing six Swedish teachers of English at upper secondary school, the study addresses which methods are mostly used by the teachers in order to encourage the improvement of students’ oral proficiency. The results of the study indicate that all the teachers tried in different manners to encourage students’ self-confidence, which would help them develop their oral proficiency. Furthermore, it was possible to conclude that the teachers shared the notion that insecurity is detrimental to the development of students’ oral proficiency. Another method that was used by the teachers was allowing students to work in either pair or groups. Even though most teachers used this method, they did point out different things that were important to think about in terms of group work. For the teachers, it was important that the students had fun during oral exercises, and thus, most teachers used different games when conducting oral activities in order to inspire a more relaxed or comfortable environment. The last concept that the teachers talked about was the usage of the target language in the classroom. Here the teachers’ ideas were not in alignment with each other. Some thought that it was good to force the students to use the target language throughout the lessons when communicating, whereas others only believed that students had to communicate orally in the target language during speaking activities. If students were insecure, it did not, according to these teachers, help the students to force them to speak English throughout the lessons. Most of the concepts that were introduced by the teachers were similar to those found in previous studies on Swedish teachers of English. Furthermore, the results of this paper could also be tied to previous research concerning oral development for L2 learners.<br>Syftet med denna studie har varit att studera hur svenska engelskalärare främjar utvecklingen av elevers muntliga färdigheter i engelska. Genom att intervjua sex svenska engelskalärare på gymnasieskolan undersöker studien vilka metoder som används mest av lärarna för att utveckla elevernas muntliga färdigheter. Resultaten av studien visar att de flesta lärare som intervjuades på olika sätt uppmuntrar elevernas självförtroende, vilket i sin tur hjälper dem att utveckla deras muntliga färdighet. Tanken om att osäkerhet är skadligt för elevers utveckling av muntlig färdighet delades av alla lärare som intervjuades. En annan metod som användes av lärarna var att tillåta elever att arbeta i par eller grupper. Även om de flesta lärare använde den här metoden pekade de på olika saker som var viktiga att tänka på när det gällde grupp- och pararbeten. Nästa metod som lärarna använde berörde inspirerandet av en mer avslappnad eller bekväm miljö som möjliggör utvecklingen av elevers muntliga färdigheter. För lärarna var det viktigt att eleverna hade kul under muntliga övningar, och sålunda använde de flesta lärare olika spel när de utförde muntliga aktiviteter. Det sista konceptet som lärarna talade om var användningen av målspråket i klassrummet. Här var lärarens idéer inte i linje med varandra. Vissa trodde att det var bra att tvinga eleverna att använda målspråket under hela lektionen medan andra inte trodde det hjälpte elevernas utveckling av sitt muntliga språk. Om en student var osäker, hjälpte det inte, enligt dessa lärare, att tvinga studenten att tala engelska under lektionerna. De påpekade dock att eleverna var tvungna att under talaktiviteter och muntliga presentationer interagera på målspråket. De flesta av de koncept som lärarna introducerade liknade dem som hittades i tidigare studier om svenska engelskalärare. Dessutom kan resultaten av denna uppsats kopplas till tidigare forskning kring oral development for L2 learners.
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Grommes, Patrick. "Prinzipien kohärenter Kommunikation." Doctoral thesis, Humboldt-Universität zu Berlin, Philosophische Fakultät II, 2007. http://dx.doi.org/10.18452/15615.
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Die Dissertation zeigt, dass die Prinzipien kohärenter Kommunikation auf psycholinguistisch begründete Prinzipien der Textproduktion zurückzuführen sind. Die gemeinsame Basis von Text- und Dialogproduktion ist die Quaestio, die als leitende Frage Vorgaben für den Aufbau eines Textes, aber auch einer einzelnen Äußerung macht. Im Text sichert die Quaestio Kohärenz, indem die Textbausteine auf der konzeptuellen Ebene – und nicht allein durch lexikalische oder grammatische Mittel – verknüpft werden. Das bedeutet, dass Kohärenzherstellung eine kognitive Leistung ist, die nicht allein rezeptiv zu erbringen ist, sondern auch bei der Sprachproduktion die Beachtung von Planungsvorgaben verlangt. Zunächst werden die Begriffe Kohärenz und Kohäsion und verschiedene Ansätze zu ihrer Beschreibung diskutiert. Außerdem werden Methoden der Dialoganalyse einander gegenüber gestellt. In dieser Diskussion werden unter anderem Rhetorical Structure Theory und Centering-Theorie behandelt. Da die Arbeit eher strukturelle mit qualitativen Analysen verbindet, werden methodische Zugänge zur Dialoganalyse wie die Konversationsanalyse, aber auch Clark’s sozialpsychologischer Ansatz der joint actions und joint activities sowie Pickering’s und Garrod’s alignment-Theorie aufgegriffen. Letztlich wird auf das Quaestio-Modell von Stutterheim zurückgegriffen, da es aus psycholinguistischer Perspektive den weitesten Erklärungsrahmen bietet. Der Hauptteil der Dissertation ist der Modell-Entwicklung anhand authentischer Gesprächsdaten gewidmet. Schließlich werden Prinzipien der Quaestio-Bearbeitung im Dialog entwickelt. Da unterschiedliche Gesprächssituationen untersucht werden, liefert diese Arbeit ein Inventar an Kohärenzprinzipien samt ihrer charakteristischen Merkmale, das nicht nur die Analyse beliebiger weiterer Gespräche erlaubt, sondern beispielsweise auch zur Entwicklung von Kommunikationsroutinen eingesetzt werden kann. So werden Anwendungsperspektiven psycholinguistischer Forschung erkennbar.<br>This doctoral thesis shows in how far principles of coherent communication can be traced back to psycholinguistically founded principles of text production. The so-called quaestio forms the common basis of text and dialogue production. As an implicit underlying question it sets preferences for the structure of a whole text as well as a single utterance. The quaestio ensures coherence of texts on a conceptual basis rather than merely through the use of lexical or grammatical means. Thus, the production of coherence can be seen as cognitive achievement not only by listeners, but also by speakers who have to follow planning constraints. The thesis discusses the terms coherence and cohesion as well as descriptive approaches dealing with these terms. Additionally, methods of dialogue analysis are confronted with each other. This discussion treats for example Rhetorical Structure Theory and Centering-Theory. The thesis discusses diverse methodological approaches, because it combines structural with qualitative analyses. Thus approaches such as Conversation Analysis, Clark’s concept of joint actions and joint activities, but also Pickering’s and Garrod’s alignment-theory are being treated. In the end the quaestio approach by Stutterheim is chosen, because it offers the widest explanatory framework from a psycholinguistic point of view. The main part of the thesis is dedicated to detailed analyses of real-life dialogue. In conclusion, principles of quaestio management in dialogues are proposed. Because the study treats a wide variety of interaction settings, it delivers a set of principles of coherence and their typical features that allows not only for analyses of any other set of dialogues, but may also support the development of communication routines. Therefore, this thesis hints on application scenarios of psycholinguistic research.
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Almasri, Hanine. "Toxicologie des mélanges de pesticides chez des abeilles exposées à un agent pathogène : action combinée de l'agent pathogène Nosema ceranae, de l'insecticide imidaclopride, du fongicide difénoconazole et de l'herbicide glyphosate Mixtures of an insecticide, a fungicide and a herbicide induce high toxicities and systemic physiological disturbances in winter Apis mellifera honey bees Toxicity of the pesticides imidacloprid, difenoconazole and glyphosate alone and in binary and ternary mixtures to winter honey bees: effects on survival and antioxidative defenses Toxicological status changes the susceptibility of the honey bee Apis mellifera to a single fungicidal spray application Physiological effects of the interaction between Nosema ceranae and sequential and overlapping exposure to glyphosate and difenoconazole in the honey bee Apis mellifera." Thesis, Avignon, 2020. http://www.theses.fr/2020AVIG0722.
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Les données scientifiques actuelles suggèrent un déclin de la diversité et de l’abondance des insectes, y compris les abeilles domestiques Apis mellifera. Ces dernières sont confrontées à de fortes pertes de colonies dans plusieurs régions du monde telles que l’ouest de l’Europe et les États-Unis. De nombreuses études suggèrent que l’origine du déclin des colonies d’abeilles est multicausale et identifient les pesticides et les agents pathogènes comme étant les principaux contributeurs à ce déclin. La co-exposition des abeilles à de multiples pesticides et l’infection par plusieurs pathogènes constituent un phénomène courant. Cependant, les recherches sur les effets des mélanges de pesticides n’ont pas fait l’objet d’un intense développement. Ainsi, les travaux conduits dans le cadre de cette thèse ont été focalisés sur la détermination de la toxicité des mélanges de pesticides, appliqués à des niveaux d’exposition environnementaux, en présence d’un agent pathogène. Le choix s’est porté sur l’étude des interactions entre un insecticide néonicotinoïde, l’imidaclopride, un fongicide azole, le difénoconazole, et un herbicide, le glyphosate, en présence de l’agent pathogène Nosema ceranae. Les résultats des différentes études effectuées durant cette thèse, révèlent la complexité des études sur les mélanges de pesticides. Ces travaux nous ont permis de constater que les effets d’un mélange de pesticides peuvent fortement varier en fonction des concentrations des pesticides constituant le mélange. L’augmentation du nombre de substances et du niveau d’exposition, n’induit pas nécessairement une augmentation de la toxicité du mélange. De plus, les effets du mélange peuvent varier en fonction de la séquence d’exposition aux pesticides et de l’état sanitaire des abeilles. Les mélanges de pesticides affectent l’état physiologique des abeilles suite à une réponse systémique liée à des perturbations de mécanisme généraux tels que le stress oxydant. Cependant, ces trois pesticides, seuls et en mélanges n’ont aucun effet sur l’installation du microbiote intestinal à des niveaux d’exposition environnementaux<br>Current scientific findings suggest a decline in the diversity and abundance of insects, including the honey bee Apis mellifera. The latter are facing high colony losses in several regions of the world such as Western Europe and the United States. Numerous studies suggest that the origin of bee colony decline is multi-causal and identify pesticides and pathogens as the main contributors to this decline. Co-exposure of honey bees to multiple pesticides and infection by multiple pathogens are common phenomena. However, research on the effects of pesticide mixtures has not been extensively developed. Thus, the thesis work has focused on determining the toxicity of pesticide mixtures, applied at environmental exposure levels, in the presence of pathogens. The choice was made to study the interactions between a neonicotinoid insecticide, imidacloprid, an azole fungicide, difenoconazole, and a herbicide, glyphosate, in the presence of the pathogen Nosema ceranae. The results of the different studies, carried out during this thesis, reveal the complexity of the studies on pesticide mixtures. The work allowed us to notice that the effects of a pesticide mixture can vary according to the concentrations of the pesticides constituting the mixture. The increase of the number of substances and the level of exposure does not necessarily induce an increase of the toxicity of the mixture. Furthermore, the effects of the mixture may vary depending on the sequence of exposure to the different pesticides and the health status of the honey bees. Pesticide mixtures affect the physiological state of individuals as a result of a systemic response related to disturbances of general mechanisms such as oxidative stress. However, these three pesticides, alone and in mixtures, have no effect on the installation of the intestinal microbiota at environmental exposure levels