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McHugh, Catherine Jane. "The delivery of DNA vaccines using particulate and non-particulate adjuvants". Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.413241.
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Ouhssain, Malika. "Caractéristiques et origines de la variabilité diurne des propriétés optiques". Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066138/document.
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Mon travail de thèse s’est développé, pour le cas particulier des observations satellitales à partir de l’orbite géostationnaire. Le but général a été de caractériser la variabilité diurne des propriétés optiques inhérentes (i.e. les coefficients d‘atténuation et de rétrodiffusion particulaire, cp et bbp) et apparentes (i.e. la réflectance, R) des eaux océaniques (« forme » du cycle diurne, amplitude, variations saisonnières, causes). Ces propriétés optiques déterminent le signal qu’un instrument embarqué à bord d’un satellite peut observer. Cette étude est une étape préliminaire permettant de comprendre la physique du problème, avant de pouvoir évaluer la possibilité de quantifier cette variabilité diurne à partir des observations satellitaires. La variabilité diurne de cp et bbp est donc étudiée en fonction des saisons définies selon les conditions physico-trophiques: le mélange, le bloom, son déclin, et l’oligotrophie. cp et bbp sont caractérisés par un cycle diurne, augmentation le jour et diminution la nuit, confirmant les tendances générales connues. Ce phénomène se produit durant toutes les saisons avec une variabilité intra-saisonnière qui différencie les cycles de cp et bbp: cp montre une amplitude plus large durant le bloom, contrairement à bbp les minima de cp et bbp sont synchronisés tandis que les maxima de bbp sont atteints 3 à 6 h avant ceux de cp, sauf pendant le bloom. L’augmentation journalière de bbp se reflète dans les changements de R. Toutefois, les résultats ont montré que l’inversion ne permet pas de reproduire l’augmentation journalière de bbp de façon satisfaisante. Les techniques d’inversion existantes ne sont pas adaptées pour une utilisation à haute fréquenceMy thesis is developed for the particular case of satellites observations from geostationary orbit. The overall aim was to characterize the diel variability of water inherent (i.e. the particulate beam attenuation and backscattering coefficients, cp and bbp) and apparent (i.e. reflectance, R) optical properties (“shape”of diel cycle, amplitude, seasonal variations, origins). These properties determine the signal which is observed from sensor aboard satellite. This study is a preliminary step in understanding the physical problem, before assessing the possibility of quantifying the diel variability from satellite observations. Diel variability of cp and bbp is studied by season, as defined by physical and trophic conditions: mixing, bloom proliferation, its decline, and oligotrophy. Both cp and bbp are characterized by a diel cycle of daytime increase and nighttime decrease, confirming known general trends. This occurs across all seasons, but intra-seasonal variability differed between cp and bbp cycles: unlike bbp, cp show larger amplitude of diurnal variation during the bloom cp and bbp minima are synchronized while bbp minima are attained 3-6 h before those of cp, except during the bloom. Daily changes of R are consistent with the variations of bbp. Nevertheless, it is still difficult to reproduce the diurnal increase of bbp by inversion of R. The differences observed between in situ and modeled values of bbp suggest that the performance of inversion is degraded when it is used at high frequency
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Raj, Kolupula Yuva Deva. "Chromatic Particulate Monitoring System". Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.526954.
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Beauboeuf, Daniel P. "Microscopy investigations of ash and particulate matter accumulation in diesel particulate filter surface pores". Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59894.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 60).
There has been increased focus on the environmental impact of automobile emissions in recent years. These environmental concerns have resulted in the creation of more stringent particulate matter emissions regulations in the United States and European Union. These limits have forced diesel engine manufacturers to reduce particulate matter (PM) emissions by an order of magnitude beginning in 2007. Diesel particulate filters (DPF) provide the most effective means of reducing PM emissions from diesel exhaust. DPFs can reduce over 99% of PM in the exhaust. DPF effectiveness is limited by the accumulation of ash. Ash is comprised of incombustible material from engine lubricants. Engine oil additives based on P, Zn, S, Ca, and Mg are responsible for the majority of ash. Ash accumulation in DPFs reduces their useful life by plugging the filter's inlet channels. Ash deposition leads to increased pressure drop across the DPF, which reduces the engine's performance and negatively impacts fuel economy. The process of ash accumulation in DPF channels is not well understood. This research is focused on exploring the ash interactions with DPF walls, pores, and the catalyst washcoat. Based on scanning electron microscopy analysis of ash loaded DPFs from the field and from filters loaded with ash in the laboratory, a mechanism for ash accumulation is presented.
by Daniel P. Beauboeuf.
S.B.
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Gómez, Ana Maria Mosquera. "Modelagem da dispersão de material particulado na atmosfera a partir de fontes estacionárias utilizando fluidodinâmica computacional". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-24102017-151559/.
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Neste trabalho propõe-se uma análise da dispersão de material particulado gerado por fontes estacionárias, aplicando ferramentas de Fluidodinâmica Computacional (em inglês Computatonal Fluid Dynamics, CFD), usando um modelo Euleriano para o escoamento e Lagrangeano para as partículas, em estado estacionário no software Fluent. A verificação da modelagem é apresentada em duas sessões, a primeira compreende o estudo do escoamento atmosférico em condições de estabilidade neutra incluindo os efeitos das heterogeneidades do terreno, no caso, um monte de 126m de altura em escala real. Foram comparados diferentes modelos de turbulência: padrão, RNG e parametrizado para o caso atmosférico. Os três modelos apresentaram desempenho semelhante e descrevem satisfatoriamente as tendências dos dados experimentais. A segunda, o modelo lagrangeano baseado no tempo de vida dos turbilhões (em inglês Discrete Random Walk, DRW) foi utilizado para representar a distribuição de concentrações de material particulado em um ambiente confinado. Os resultados numéricos descrevem satisfatoriamente os perfis de concentrações das partículas, porém subestimam os valores na região próxima à parede, o que indicaria que uma melhor aproximação da deposição das partículas deve ser considerada. Após estes estudos, esta abordagem euleriana-lagrangeana foi aplicada ao caso da dispersão de material particulado em condições de atmosfera neutra em uma região do Polo Cerâmico de Santa Gertrudes-SP, local responsável pela maior produção de revestimentos cerâmicos do Brasil. O trânsito de caminhões nas estradas não pavimentadas foi identificado como fonte de material particulado que atinge o perímetro urbano da cidade. Estudaram-se também as contribuições das atividades referentes à exploração das minas de argila e a preparação do solo para uso agrícola, apesar desta última não soma uma carga relevante ao ser comparada com as duas anteriores. Além da influência das fontes mencionadas, fontes de origem industriais localizadas dentro da cidade também foram consideradas no cenário.In this study an analysis of the dispersion of particulate matter generated by stationary sources is proposed, by applying Computational Fluid Dynamics (CFD) tools, using an Eulerian model for the flow and a Lagrangean model for the particles, under steady-state conditions in the Fluent software. The model validation is presented in two sessions, the first comprises the study of the atmospheric flow under conditions of neutral stability, including the effects of the heterogeneities of the terrain. In this case, the air flow past a 126m high hill in real scale was adopted. Different turbulence models were compared: standard k-?, k-? RNG and parametrized k-?. The three models presented similar performance and described satisfactorily the trends of the experimental data. Subsequently, the Lagrangean model based on the Eddy life time (DRW - Discrete Random Walk) was used to represent the distribution of particulate matter concentrations in a confined environment. The numerical results satisfactorily describe the particle concentration profiles, but underestimate the values in the region near the wall, which would indicate that a better approximation of the particle deposition should be considered. After these studies, this Eulerian- Lagrangean approach was applied to the case of dispersion of particulate material under neutral atmosphere conditions in a region around the city of Santa Gertrudes-SP, where the Ceramic Complex is responsible for the largest production of ceramic tiles in Brazil. Transit of trucks on unpaved roads has been identified as a source of particulate matter that reaches the urban perimeter of the city. The contributions of the activities related to mining and the preparation of the soil for agricultural use were also studied, although this last one does not add a significant load when compared with the two previous ones. In addition to the influence of the mentioned sources, industrial sources located inside the city also contribute to the scenario.
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Faccio, Andréa Tedesco. "Abordagem metabolômica no estudo da exposição gestacional à poluição atmosférica". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-07122015-101244/.
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Há fortes evidências dos efeitos negativos da exposição gestacional a poluentes atmosféricos. No entanto, mecanismos de atuação de poluentes não são bem compreendidos. Alterações fisiológicas anômalas na progenitora, durante o período de gravidez, podem causar mudanças permanentes na prole, que podem desencadear futuras doenças na vida adulta. Portanto, o estudo dessas alterações maternas é importante. A metabolômica é definida como a análise global do metaboloma de um organismo em experimentos comparativos, com o objetivo de observar mudanças relativas da abundância dos metabólitos, o aparecimento ou desaparecimento de metabólitos, e pode fornecer uma melhor compreensão dos mecanismos de funcionamento celular dos organismos a nível molecular. Nesse trabalho, um estudo experimental de exposição gestacional materna, ao material particulado fino (MP2,5), foi realizado, para avaliar os efeitos dessa exposição no metabolismo, por meio da análise metabolômica global da urina de camundongos fêmeas progenitoras expostas ao MP2,5 (grupo teste) ou a ar filtrado (grupo controle) durante a gestação. Um método cromatográfico e de preparo de amostra para metabolômica urinária por HILIC-MS foram otimizados. Para a otimização da condição cromatográfica, foram investigados a influência de aditivos, concentração de sal e pH da fase móvel, bem como, a rampa do gradiente. A melhor condição foi escolhida por meio da avaliação do formato de pico, da intensidade relativa e do CV do tempo de retenção para 15 m/z selecionados, assim como, pelo número total de molecular features e CV da intensidade desses molecular features. A melhor condição obtida apresenta 20 mmol/L de formiato de amônio em sua composição do solvente B da fase móvel e 95% acetonitrila e 5% solução aquosa 400 mmol/L de formiato de amônio na composição do solvente A. Para o preparo de amostra, foram examinados diferentes solventes orgânicos e suas misturas, para a precipitação de proteínas da urina. O isopropanol foi o solvente apresentou os melhores resultados para o preparo de amostra. Dessa forma, com o método analítico otimizado, as amostras de urina de camundongos fêmeas prenhas foram submetidas à analise metabolômica global por HILIC-MS. O metaboloma dos animais foi bastante alterado pela exposição gestacional ao material particulado. Observou-se alteração dos níveis de carnitinas, aminoácidos, peptídeos, entre outros. Há também indícios de que a poluição atmosférica alterou a microbiota intestinal dos animais, devido ao aumento de N-óxido de trimetilamina, um metabólito que também é relacionado ao processo de aterosclerose. Níveis de metabólitos relacionados ao metabolismo da histidina também foram alterados devido a exposição ao MP2,5. Níveis de carnitina e acilcarnitinas foram aumentados no teste, sugerindo alteração da produção de energia na mitocontria.There are strong evidences regarding negative effects of gestational exposure to air pollution. However, the mechanisms of action of air pollutants are not well established. Maternal anomalous physiological changes during pregnancy may cause permanent changes in offsprings, that might initiate future diseases in adult life. Therefore, the study of those maternal changes during pregnancy is important. Metabolomics is defined as the global analysis of the metabolome of an organism in comparative studies, for the measurement of relative changes in the metabolite abundance, appearance or disappearance. Metabolomics might provide a better understanding of cellular functioning at the molecular level. In this work, an experimental study of maternal gestational exposure to fine particulate matter (PM2.5) was accomplished to evaluate the effects of this exposure to the metabolism, by an untargeted metabolomics analysis of urine from pregnant mice exposed to PM2.5 or to filtered air during pregnancy. A chromatographic and sample preparation methods for urinary untargeted metabolomics analysis by HILIC-MS were optimized. For the chromatography optimization, the influence of mobile phase additives, salt concentration and pH, as well as, the gradient ramp were investigated. The best condition was chosen by the evaluation of peak shape, relative intensity and retention time CV of 15 selected m/z, as well as, the total number of molecular features and the intensity CV of those molecular features. The best condition comprises of 20 mmol/L of ammonium formate as solvent B, and 95% acetonitrile and 5% 400 mmol/L of ammonium formate as solvent A, in the composition of the mobile phase. For the sample preparation, different solvents, along with, their mixtures were examined for the urine protein precipitation. Isopropanol was the solvent that presented the best results for sample preparation. Thus, after the analytical method optimized, urine samples from the progenitors were submitted to untargeted metabolomics analysis by HILIC-MS. The animals\' metabolome were significantly changed by the gestational exposure to particulate matter. It was observed changes in the levels of carnitines, amino acids, peptides, among others. There is some indication that the air pollution has altered the gut microbiota, due to the enhancement of trimethylamine N-oxide (TMAO), a metabolite that is also related to the atherosclerosis process. The level of metabolites related to histidine metabolism were also altered due to PM2.5 exposure. Carnitine and acylcarnitine levels were also increased in the test group, suggesting an altered energy production in the mitochondria.
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Souza, Milena Gouveia Oliveira de. "Avaliação da concentração de arsênio em partículas fracionadas por tamanho na atmosfera do Recôncavo Baiano". reponame:Repositório Institucional da UFBA, 2011. http://www.repositorio.ufba.br/ri/handle/ri/10027.
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CNPQ
Atualmente, um dos maiores problemas mundiais é a poluição atmosférica, oriunda essencialmente de fontes antrópicas. Os grandes impactos ambientais, como a degradação da qualidade do ar, são resultados dos processos de desenvolvimento urbano e industrial. O material particulado (MP) tem sido alvo de vários estudos devido aos efeitos nocivos causados ao meio ambiente e a saúde humana. O arsênio, um metalóide que apresenta características tanto de metal como de não-metal, é considerado altamente tóxico. A associação do arsênio ao material particulado pode provocar sérios danos à saúde da população. Os níveis de toxicidade do arsênio são dependentes de sua forma química. As espécies inorgânicas de arsênio, arsenito (AsIII) e arseniato (AsV), são também consideradas agentes carcinogênicos. O Recôncavo Baiano é uma região que apresenta grande importância ambiental, social e econômica para o estado da Bahia. Nesta área encontram-se portos, terminais marítimos e diversos pólos industriais que são as principais fontes de emissão de poluentes para o meio ambiente. O presente trabalho teve por objetivo verificar a concentração do arsênio presentes tanto nas partículas finas, quanto nas partículas grossas do material particulado atmosférico do Recôncavo Baiano, para avaliar as contribuições deste poluente à saúde da população exposta. A determinação de arsênio em material particulado, utilizando a digestão, com HNO3, e a técnica de espectrometria de fluorescência atômica acoplada à geração de hidreto (HG-AFS), mostrou-se eficiente para a matriz estudada com limite de detecção e quantificação de 0,3 ng m-3 e 1 ng m-3, respectivamente. As concentrações médias de arsênio, obtidas no material particulado em algumas regiões do Recôncavo Baiano, estavam em torno de 30 ng m-3, valor cinco vezes maior que o recomendado pela União Européia (6 ng m-3). O arsênio presente no material particulado encontra-se substancialmente nas partículas finas. Alertando para os riscos de exposição da população, nos municípios onde foram feitas as amostragens. Os resultados apresentados neste trabalho são indicativos da necessidade de se atualizar os padrões de qualidade do ar para o Brasil, incluindo outros poluentes como o arsênio
Salvador
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Chang, Hong. "Hydraulic Fracturing in Particulate Materials". Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4957.
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For more than five decades, hydraulic fracturing has been widely used to enhance oil and gas production. Hydraulic fracturing in solid materials (e.g., rock) has been studied extensively. The main goal of this thesis is a comprehensive study of the physical mechanisms of hydraulic fracturing in cohesionless sediments. For this purpose, experimental techniques are developed to quantify the initiation and propagation of hydraulic fractures in dry particulate materials. We have conducted a comprehensive experimental series by varying such controlling parameters as the properties of particulate materials and fracturing fluids, boundary conditions, initial stress states, and injection volumes and rates. In this work, we suggest principle fundamental mechanisms of hydraulic fracturing in particulate materials and determine relevant scaling relationships (e.g., the interplay between elastic and plastic processes).
The main conclusion of this work is that hydraulic fracturing in particulate materials is not only possible, but even probable if the fluid leak-off is minimized (e.g., high flow rate, high viscosity, low permeability). Another important conclusion of this work is that all parts of the particulate material are likely to be in compression. Also, the scale effect (within the range of the laboratory scales) appears to be relatively insignificant, that is, the observed features of fractures of different sizes are similar.
Based on the observed fracture geometries, and injection pressures we suggested three models of hydraulic fracturing in particulate materials. In the cavity expansion or ??e driving model, the fracturing fluid is viewed as a sheet pile (blade) that disjoints the host material, and the cavity expansion occurs at the fracture (blade) front. The shear banding model is also consistent with a compressive stress state everywhere in the particulate material and explains the commonly observed beveled fracture front. The model of induced cohesion is based on the fluid leak-off ahead of the fracture front. The induced cohesion may be caused by the tensile strain near the fracture tip (where the stress state is also compressive), which, in turn, induces the cavitation of the leaked-off fluid and hence capillary forces.
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Johnston, Nicola Jane. "Particulate production during dental procedures". Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492647.
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The objectives of this investigation were to determine particulate production during routine clinical orthodontic and dental laboratory procedures and to investigate what factors can be employed to minimise exposure to such dust particles.
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Wang, Huaijun. "Creating Virtual Wood Particulate Composites". Fogler Library, University of Maine, 2000. http://www.library.umaine.edu/theses/pdf/Wang.pdf.
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Zhang, Zhichao. "Impact attrition of particulate solids". Thesis, University of Surrey, 1994. http://epubs.surrey.ac.uk/2945/.
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Papadopoulos, Dimitris G. "Impact breakage of particulate solids". Thesis, University of Surrey, 1998. http://epubs.surrey.ac.uk/804878/.
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Al-Kassas, Raida. "Design of particulate delivery systems". Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239000.
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Hou, Ruozhou. "Acoustic monitoring of particulate flows". Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325765.
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Benedict, Mark Douglas. "Advances in anisotropic particulate simulation". Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612000.
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Kendall, Michaela. "Particulate pollution and stone deterioration". Thesis, Middlesex University, 1998. http://eprints.mdx.ac.uk/13410/.
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The soiling and damage of building surfaces may be enhanced by particulate air pollution, reducing the aesthetic value and lifetimes of historic buildings and monuments. This thesis focuses on the deposition of atmospheric particulate material to building surfaces and identifies potential sources of this material. It also identifies environmental factors influencing two deterioration effects: surface soiling and black crust growth. Two soiling models have been compared to assess their effectiveness in predicting the soiling rates of two materials - stone and wood - in five cities in Europe. An exponential decay model was found to describe the reduction of reflectance well at two of these sites, while a square root relationship is not as effective. Different measures of weekly particulate concentration were not statistically related to soiling rate, whereas S02, rainfall, and temperature were statistically related to reflectance loss over time. Wind speed and solar insolation were also indicated to influence soiling rates. Concentrations of total suspended particulate (TSP), particulate elemental carbon (PEC), total organic carbon (TOC) and thirty-nine particulate-associated hydrocarbons were measured in airborne particles at two sites in London, for one year. These hydrocarbons were also measured in black crusts from St Paul's Cathedral to relate atmospheric and deposited material, and to identify potential sources of the deposited particulate matter. Detailed scanning electron microscope-energy dispersive X-ray (SEM-EDX) analysis of black crust \ similarly indicated potential sources of these deposition layers. Analysis revealed the complex structure of these crusts, comprising gypsum "growth stems ", calcite and large numbers of particles mainly originating from oil combustion. Hydrocarbon analysis supported the fact that oil combustion - probably at Bank power station - was the dominant source of this deposited layer. Other particle morphologies were commonly found, such as those typical of coal combustion and diesel engine exhaust. Metals analyses also indicated other possible sources such as vehicles.
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Basso, Simone. "Particulate Debris Spreading and Coolability". Doctoral thesis, KTH, Kärnkraftssäkerhet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-203136.
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In Nordic design of boiling water reactors, a deep water pool under the reactor vessel is employed for the core melt fragmentation and the long term cooling of decay heated corium debris in case of a severe accident. To assess the effectiveness of such accident management strategy the Risk-Oriented Accident Analysis Methodology has been proposed. The present work contributes to the further development of the methodology and is focused on the issue of ex-vessel debris coolability. The height and shape of the porous debris bed are among the most important factors that determine if the debris can be cooled by natural circulation of water. The bed geometry is formed in the process of melt release, fragmentation, sedimentation and packing of the debris in the pool. Bed shape is affected by the coolant flow that induces movement of particles in the pool and after settling on top of the bed. The later one is called debris bed self-leveling phenomenon. In this study, the self-leveling was investigated experimentally and analytically. Experiments were carried out in order to collect data necessary for the development of a numerical model with an empirical closure. The self-leveling model was coupled to a model for prediction of the debris bed dryout. Such coupled code allows to calculate the time necessary to have a coolable configuration of the bed. The influence of input parameters was assessed through sensitivity analysis in order to screen out the less influential parameters. Results of the risk analysis are reported as complementary cumulative distribution functions of the conditional containment failure probability (CCFP). Sensitivity analyses identified: effective particle diameter and debris bed porosity as the parameters that provide the largest contribution to the CCFP uncertainty. It is found that the effect of the initial maximum height of the bed on the CCFP is reduced by the self-leveling.Kokvattenreaktorer av nordisk typ har en djup vattenbassäng under reaktorkärlet som kan utnyttjas för att kyla härdsmältan och de fragmenterade härdresterna vid ett svårt reaktorhaveri. För att bedöma effektiviteten av en sådan haverihantering har man föreslagit användande av en riskorienterad metodik för haverianalysen (ROAAM, från engelska ”Risk-Oriented Accident Analysis Methodology”). Föreliggande projekt fokuserar på kylbarhet hos härdresterna utanför reaktortanken och bidrar till den pågående vidareutvecklingen av ROAAM till ROAAM+. Höjden på och formen för den porösa ansamlingen av härdrester (här också kallad partikelbädd) är bland de viktigaste faktorerna som avgör om resteffekten kan kylas bort med hjälp av naturlig cirkulation av vattnet i bassängen. Ansamlingens geometriska form skapas under hela processen från utsläpp av härdsmältan via fragmentering och sedimentering i bassängens botten. Formen kan sedan förändras med tiden genom att partiklar rör sig och omfördelas i kylflödet. Detta fenomen kallas en självnivellerande process. I detta arbete studeras denna självnivellerande process experimentellt och analytiskt. Experimenten utfördes i en särskild experimentuppställning utformad för att att samla in data och parametrar som behövs för att simulera fenomenet och utveckla en beräkningsmodell som sluts empiriskt. Denna modell kopplades sedan till en modell för beräkning av dryout i partikelbädden. Genom denna koppling av de två beräkningsprogrammen är det är möjligt att beräkna tiden för partikelbädden att nå en kylbar konfiguration. Inverkan av variationer i modellens indata studeras med hjälp av känslighetsanalys. Härigenom identifierades de minst inflytelserika parametrarna såsom effektiv drifttid, partikeldensitet, experimentell ovisshet i de empiriska samband som används för att sluta modellen, samt omlokaliseringstid efter det att reaktorn snabbstoppats (SCRAM). Dessa parametrar avfördes sedan från den fortsatta känslighetsanalysen. Ett artificiellt neuralt nätverk tränades för att användas i stället för den kopplade koden och möjliggöra den beräkningseffektivitet som krävs för att studera hur osäkerheter i indata förs vidare i riskanalysen. Resultaten är presenterade i form av komplementära, kumulativa fördelningsfunktioner för den betingade sannolikheten för brott på reaktorinneslutningen (CCFP, från engelska ”conditional containment failure probability”). Det visas att CCFP kan variera inom ett brett område beroende på de valda kombinationerna av frekvensfunktioner för ingångsparametrarna. Resultaten visar att effektiv partikeldiameter och hög porositet är de två parametrar som ger de största bidragen till osäkerheten i CCFP. Vi har också funnit att fenomenet självnivellering har en gynnsam inverkan på CCFP och leder till lägre utsläppsrisk. Det vore värdefullt att förfina de modeller som beskriver bildandet av den initiala partikelbädden. Detta är särskilt viktigt i de scenarier där det finns kort tid för självnivellering innan partikelbädden börjar smälta igen, dvs när man har relativt hög initial temperatur i partikelbädden och/eller hög specifik värmeeffekt.
QC 20170315
APRI
18
Almeida, Antonio J. L. "Particulate carriers as immunological adjuvants". Thesis, Aston University, 1993. http://publications.aston.ac.uk/12609/.
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In recent years, much interest has focused on the significance of inducing not only systemic immunity but also good local immunity at susceptible mucosal surfaces. A new field of mucosal immunity has been established as information accumulates on gut-associated lymphoid tissue, bronchus-associated lymphoid tissue and nasal-associated lymphoid tissue (GALT, BALT and NALT, respectively) and on their role in both local and systemic immune responses. This project, following the line of investigation started by other workers, was designed to study the use of microspheres to deliver antigens by the mucosal routes (oral and nasal). Antigen-containing microspheres were prepared with PLA and PLGA, by either entrapment within the particles or adsorption onto the surface. The model protein antigens used in this work were mainly tetanus toxoid (TT), bovine serum albumin (BSA) and -globulins. In vitro investigations included the study of physicochemical properties of the particulate carriers as well as the assessment of stability of the antigen molecules throughout the formulation procedures. Good loading efficiencies were obtained with both formulation techniques, which did not affect the immunogenicity of the antigens studied. The influence of the surfactant employed on the microspheres' surface properties was demonstrated as well as its implications on the adsorption of proteins. Preparations containing protein adsorbed were shown to be slightly more hydrophobic than empty PLA microspheres, which can enhance the uptake of particles by the antigen presenting cells that prefer to associate with hydrophobic surfaces. Systemic and mucosal immune responses induced upon nasal, oral and intramuscular administration have been assessed and, when appropriate, compared with the most widely used vaccine adjuvant, aluminium hydroxide.
19
Fry, Dan. "Aggregation in dense particulate systems /". Search for this dissertation online, 2003. http://wwwlib.umi.com/cr/ksu/main.
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Furbank, Roy Jeffrey. "Drop formation from particulate suspensions". Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-05172004-100527/unrestricted/furbank%5Froy%5Fj%5F200407%5Fphd.pdf.
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Thesis (Ph. D.)--School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, 2005. Directed by F. Joseph Schork.Schork, F. Joseph, Committee Chair ; Morris, Jeffrey F., Committee Co-Chair ; Forney, Larry J., Committee Member ; Breedveld, Victor, Committee Member ; Mucha, Peter J., Committee Member ; Smith, Marc K., Committee Member. Includes bibliographical references.
21
Downard, Jared Matthew. "Particulate emissions of tire combustion". Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4615.
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The disposal of used tires represents an environmental and health hazard, especially when large stockpiles of tires start on fire. This study focuses on ambient particulate matter samples collected during the Iowa City landfill tire fire and laboratory emissions of tire combustion. Levels of elemental (EC) and organic carbon (OC), metals, polycyclic aromatic hydrocarbons (PAH), azaarenes and oxygenated PAH (oxy-PAH) were determined by thermo-optical analysis, high precision mass, inductively-coupled plasma mass spectrometry and gas chromatography mass spectrometry. Results demonstrate that tire combustion emissions are enriched in elemental carbon and PAH. Levels of hazardous metals, such as lead and zinc, are not enhanced in particulate emissions 4.2 km from the fire. In addition, fresh tire combustion emissions have increased amounts of lower molecular weight PAH in the particle phase when compared to diluted real world emissions. This is due to gas phase partitioning of lower molecular weight PAH in plume transport. To build on the prior, qualitative understanding of organic compounds in tire emissions, 15 total azaarenes and oxy-PAH were identified, including four azaarenes and three oxy-PAH that were identified in tire combustion emission for the first time. The combustion of tires has significant health implications, particularly when open burning occurs near populations. This study serves to characterize the major chemical components of tire smoke and to quantify emissions of select chemicals with known carcinogenic, mutagenic, and toxic effects.
22
Golly, Benjamin. "Etude des sources et de la dynamique atmosphérique de polluants organiques particulaires en vallées alpines : apport de nouveaux traceurs organiques aux modèles récepteurs". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENA019/document.
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Récemment, la qualité de l'air dans la région Rhône-Alpes est devenue un sujet sensible depuis sa mise en demeure par l'Union Européenne pour non respect des normes en vigueurs concernant les taux de particules fines (PM). Effectivement, certaines zones géographiques de la région connaissent de nombreux dépassements en PM10, particulièrement dans les vallées alpines durant la période hivernale. Ces dépassements en particules sont aussi accompagnés de fortes concentrations en composés organiques comme les hydrocarbures aromatiques polycycliques (HAP) constituants ces PM. Un accroissement des connaissances sur les sources de pollution atmosphérique particulaire et leurs dynamiques au sein des vallées alpines est alors nécessaire, ceci afin d'améliorer la mise en place des politiques de diminution des émissions grâce à une meilleure connaissance de l'influence des différentes sources au niveau régional. Ces travaux de thèse sont axés autour des émissions des sources industrielles encore mal connues et plus particulièrement l'industrie du carbone très présente dans les bassins industriels de ces fonds de vallées. Les approches classiques par les éléments métalliques n'étant pas spécifiques, l'exploration de la fraction organique a permis de proposer un profil chimique organique complet et d'avancer le benzo(b)naphtho(2,1-d)thiophène (BNT(2,1)), composé particulaire majoritaire de la famille des Hydrocarbures Aromatiques Polycycliques soufrés (HAPS) comme traceur de cette source. Ce composé a été détecté et quantifié sur plusieurs sites en proximité d'activités industrielles confirmant ainsi sa source potentielle. De plus le profil industriel a été introduit comme profil « source » afin d'évaluer sa robustesse dans les méthodologies de type modèle récepteur de bilan de masse comme le « Chemical Mass Balance » (CMB) et statistique comme la « Positive Matrix Factorization » (PMF). Les résultats ont confirmé l'intérêt de l'ajout des composés organiques à ces méthodologies. Ainsi, le profil industriel et les composés organiques HAPS ont permis de mieux tracer la source appelée génériquement « industrie du carbone » (combustions de charbon, de coke et de matériaux graphitiques) dans les vallées alpines mais aussi sur différents sites urbains français. En parallèle, un modèle de régression non linéaire multivarié (MRNL) a été développé pour la quantification des sources de HAP, basé sur l'utilisation de traceurs spécifiques de source (lévoglucosan, hopanes….) et de données météorologiques (gradient thermique). Son application a été validée sur un ensemble de sites alpins des vallées de l'Arve et de la Tarentaise. Un couplage entre ce modèle et les données de mesures optiques du carbone suie (BC) par aéthalomètre, a permis de proposer une solution aux mauvais résultats de corrélation entre les HAP mesurés et modélisés par le modèle MRNL sur le site de la vallée de la Maurienne. Ces faibles corrélations peuvent être liées à une mauvaise représentativité des composés organiques utilisés à tracer correctement les sources d'émission sur certains sites.Enfin, l'inter-comparaison de ces méthodologies pour la détermination des sources de HAP et plus particulièrement de la source industrielle permet de valider cette méthodologie dans une perspective opérationnelle de suivi des sources de HAP sur ces différents sites. Ces travaux réalisés au cours de cette thèse mettent en évidence l'intérêt de la caractérisation de la fraction organique des PM et les biais qui peuvent exister sur l'utilisation des composés organiques pour l'étude des sources d'émissions. Des alternatives y sont proposées afin de soulever ces ambiguïtés et d'améliorer l'étude des sources de HAP par les modèles récepteursRecently, Air quality has become a sensitive topic for Rhône-Alpes region due to the formal notice which was addressed by the European Commission for non-compliance with legislation in force. Indeed, certain geographic areas in the region present a lot of overruns in PM10, especially in Alpine valleys during winter. These overruns particles are also accompanied by high concentrations of organic compounds such as polycyclic aromatic hydrocarbons (PAHs), which constitute these PMs. An increase in khowledge about the sources of particulate air pollution and their dynamics in Alpine valleys is necessary, in order to improve the implementation of policies to reduce emissions through better knowledge of the influence of different sources at regional level. This thesis is focused around emissions from industrial sources still poorly known and particularly of the carbon industry highly present in these industrial areas of the valley bottoms. Traditional approaches by metallic elements being not specific, exploration of the organic fraction allowed to propose a complete organic chemical profile. In addition they led us to evidence the benzo(b)naphtho(2,1-d)thiophene (BNT(2,1)), the most abundant particulate compound of the family of sulfur-containing polycyclic aromatic hydrocarbons (PASHs), as a tracer of this source. This compound was detected and quantified on multiple sites in near industrial activities confirming its potential source. In addition the industrial profile was introduced as profile “source” in order to assess its robustness in methodologies of receptor model like the “Chemical Mass Balance “(CMB) and the “Positive Matrix Factorization” (PMF). The results confirmed the interest of the addition of organic compounds to these methodologies. Thus, the industrial profile and the PASHs compounds have allowed to better trace the source usually called “carbon industry” (coal, coke and graphite materials combustions) in the Alpine valleys but also in different French urban sites. In parallel, a non linear regression model (NLRM) was developed to PAH source apportionment, based on the use of specific molecular markers (levoglucosan, hopanes…) and of meteorological data (altitudinal temperature lapse rate). Its implementation has been validated on a set of sites of the Alpine valleys of Arve and Tarentaise. Coupling between this model and the optical measurements of black carbon (BC) by aethalometer, allowed to propose a solution to the poor performance of correlation between PAHs measured and modeled by NLRM model on this site of the Maurienne valley. These low correlations may be related to poor representativeness of organic compounds used to correctly trace the emission sources at some sites. Finally, the inter-comparison of these methodologies for the determination of PAH sources and especially of industrial source allows to validate this methodology in an operational perspective of monitoring of PAH levels on these sites. The work performed during this thesis highlights the interest of the characterizatin of the organic fraction of PM and the biases that may exist on the use of organic compounds for the study of the emission sources. Some alternatives are suggested to clarify ambiguities and improve the source apportionment of PAHs by receptor models
23
Válio, Vinícius Mori. "Análise do material particulado atmosférico em uma região de São Carlos-SP". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-13082015-144101/.
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O presente trabalho avaliou a qualidade do ar de uma área central da cidade de São Carlos-SP, mais precisamente no campus 1 da Universidade de São Paulo. Nessa região há grande movimentação de pessoas e veículos, principalmente durante o horário comercial. Esta avaliação foi feita com base na determinação de um dos parâmetros utilizados para verificar a qualidade do ar, o material particulado (MP) inalável em suspensão, ou seja, partículas que possuem diâmetro aerodinâmico menor ou igual a 10 μm e podem penetrar no sistema respiratório, sendo portanto, nocivas à saúde humana. O MP foi determinado em suas frações de 2,5 e 10 μm de diâmetro (MP10 e MP2,5). Duas metodologias diferentes foram utilizadas para determinar a concentração do material particulado em suspensão, fotometria por espalhamento de luz, através do equipamento ADR-1500 e gravimetria, através do PEM (Personal Enviromental Monitor). Os valores obtidos pelo método gravimétrico foram superiores aos resultados encontrados através da fotometria. As concentrações obtidas foram comparadas com os limites recomendados pela Organização Mundial da Saúde para o MP em suas frações de 2,5 e 10 μm, iguais respectivamente a 25 e 50 μg/m3. Além do material particulado foram obtidos dados para temperatura, umidade relativa e precipitação. As médias obtidas para as concentrações de MP10 e MP2,5, com o método gravimétrico, o qual fornece os resultados mais confiáveis, foram iguais respectivamente a 48,8 e 23,1 μg/m3, muito próximas portanto, de seus limites correspondentes. As menores concentrações obtidas para o MP10 foram, em sua maioria, verificadas em dias chuvosos, tanto através do PEM como do ADR. As concentrações de MP2,5, obtidas somente através do PEM, também apresentaram os menores valores em dias com chuva. Foi desenvolvido um modelo matemático que prevê o comportamento do MP10 durante as precipitações, evento este que se mostrou o mais importante na influência da concentração de material particulado atmosférico.This study evaluated the air quality of a central area of the city São Carlos-SP, more precisely on the Campus 1 of the University of São Paulo. In this region there is a large movement of people and vehicles, manly during business hours. This evaluation was made based on determination of one parameter used to verify air quality, the inhalable particulate material (PM) suspended in the air, in other words, particles which have aerodynamic diameter less or equal to 10 μm and can penetrate in the respiratory system, therefore, harmful to human health. The PM was determined in its fractions from 2,5 and 10 μm of diameter (PM10 e PM2,5).). Two different methodologies were used to determinate the concentration of particulate suspended material, photometry by scattered light, using the equipment ADR-1500, and gravimetry, thru PEM (Personal Environmental Monitor). The data obtained from gravimetry were higher than the results found thru photometry. The concentrations found were compared to the limits recommended by World Health Organization for PM and its fractions of 2,5 and 10 μm, equal to 25 and 50 μg/m3. Besides PM, temperature, relative humidity and precipitation were measured. The average values for the concentrations of PM10 and PM2,5 , using gravimetry, which provide more reliable results, it were equal to 48,8 and 23,1 μg/m3, therefore really close to their corresponding limits. The lower concentrations seen for PM10 were, mostly, verified on rainy days, using PEM and ADR. The concentrations of PM2,5 , obtained just using PEM, also had the lowest values during rainy days. A mathematical model was developed to predict PM10 behavior during precipitations, this event has shown to have the most important influence on the concentration of atmospheric particulate matter.
24
Guan, Jingjiao. "Microfabricated particulate devices for drug delivery". Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1118247862.
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Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xxiii, 163 p.; also includes graphics. Includes bibliographical references (p. 118-123). Available online via OhioLINK's ETD Center
25
Estapa, Margaret L. "Photochemical Reactions of Particulate Organic Matter". Fogler Library, University of Maine, 2011. http://www.library.umaine.edu/theses/pdf/EstapaM2011.pdf.
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Falk, Lissel Linus, i Jesper Kristoffersson. "Acoustical properties for diesel particulate filters". Thesis, KTH, Farkost och flyg, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-103567.
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Mercer, Tim. "Particulate dispersions for magnetic recording media". Thesis, University of Central Lancashire, 2001. http://clok.uclan.ac.uk/21059/.
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The study of a magnetic recording media dispersion has been carried out using hindered settling analysis, the purpose of which was to probe the equilibrium state structure in zero applied magnetic field. The system chosen for the main study was based on a commercial formulation of a y-Fe 203 suspension of 0.3 j.tm length acicular particles, with aspect ratio 5: 1, that was used to manufacture a back-up/archive tape. From the sedimentation analysis, a large fraction of fluid (- 86 % by volume of the settling unit) was estimated to be trapped within the clusters of particles that make-up the overall dispersion structure. Confidence in the result was given by correction of the classical hindered settling models to account for the trapped fluid. In this manner, the range of Steinour and Kozeny-Carman parameters evaluated reduced near to, or agreed with, the fundamental values found by the original authors on simple model systems that contained little to no trapped fluid. Near- Newtonian fluid measurements resulted in an equivalent Stokes particle diameter of - 6.7 Jim. A computer simulation of hindered settling has been developed, based on a laminae concept and the Kozeny-Carman equation, in order to complement the experimental investigation. The concentration profiles over columii height compared well with those obtained using a scanning column magnetometer to give an enhanced description of the hindered settling phenomena. This showed that the descending 'plug' of constant solids concentration falls down into, and is continually subsumed by, the rising layers of the lower compression region. The plug effectively contracts about its mid-point and the initial constant rate of fall is only maintained up to the point where the plug is destroyed. It was also found that the model only gave a reasonable comparison with experiment when the effective ratio of trapped fluid was large; giving further confidence in the trapped fluid estimate. The theory of the scanning column magnetometer technique has been developed beyond that already known. This resulted in good agreement between theory and experiment in characterising the main detection coil response, or 'form factor' and means that future design work will be enhanced. The effects of magnetic interaction in the magnetic media dispersion have been investigated by varying the magnetic y-Fe 203 content by dilution with cz-Fe 203 (produced from the same particles) whilst holding the total particle concentration constant. The resultant increase in sedimentation with magnetic interactions has been interpreted in terms of hindered settling theory as being due to the formation of clusters by magnetostatic attraction. Extension of the experiment should give a strong indication of the extent that magnetic particles trap fluid in comparison to their non-magnetic depletion flocculated precursor. This could be significant in the context of the drying stage of the magnetic recording media production process.
28
El-Gallab, Mariam S. "Machining of particulate metal matrix composites". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0030/NQ66206.pdf.
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Murphy, Angela Mary. "Clustering in particulate metal matrix composites". Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242540.
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Riaz, Shahid. "Titanium based composites containing particulate carbides". Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264184.
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Levesley, John Antony. "Particulate separation by size and shape". Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303597.
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Coelho, L. "Gas percolation through segregated particulate beds". Thesis, University of Cambridge, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597802.
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Moving beds are devices where a slow flow of particulate solids moving under the influence of gravity is contacted with a flow of gas. Heat transfer rates, mass transfer rates, and consequently reaction rates, for these devices are often modelled using information from well-packed fixed beds. It has been found, however, that moving beds behave differently from well-packed fixed beds (Paterson et al. 1991). The cause of this different behaviour is a bed structure, which is a consequence of the movement of the particles, that yields gas flow maldistribution (Crawshaw et al., 1993). Gas flow maldistribution in moving beds was extensively studied by Moppett (1996) through determinations of gas residence time distributions (RTDs) and radial profiles of axial interstitial gas velocity. These results were obtained in beds of uniform sized particles. The present work extends the study of moving beds to cases where the bed is formed with mixtures of particles of different sizes. The observation of particle segregation by means of particle distribution determinations was carried out with the implementation of two novel techniques, the particle sampling device and the setting of the bed with gelatine techniques. The moving bed structures were further probed using gas flows, specially by the determination of gas RTDs and radial profiles of axial interstitial gas velocity. The significance of the mass fraction of the different sized particles in the mixture forming the beds and the conditions of the particle inlet were both analysed. It was found that the particles of different sizes segregate and the amount of the segregation is strongly dependent on the conditions used for the inlet of the particles into the bed, namely the diameter of the particle inlet tube and the free-fall gap between the top of the column and the top surface of the bed. Particle segregation causes moving bed structures which yield extreme gas flow maldistribution.
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Dickerson, Andrew K. "Mosquito flight adaptations to particulate environments". Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51773.
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Flying insects face challenging conditions such as rainfall, fog, and dew. In this theoretical and experimental thesis, we investigate the survival mechanisms of the mosquito, Anopheles, through particles of various size. Large particles such as falling raindrops can weigh up to fifty times a mosquito. Mosquitoes survive such impacts by virtue of their low mass and strong exoskeleton. Smaller particle sizes, as present in fog and insecticide, pose the greatest danger. Mosquitoes cannot fly through seemingly innocuous household humidifier fog or other gases with twice the density of air. Upon landing, fog accumulates on the mosquito body and wings, which in small quantities can be shaken off in the manner of a wet dog. Large amounts of dew on the wings create a coalescence cascade ultimately folding the wings into taco shapes, which are difficult to dry. The insights gained in this study will inform the nascent field of flapping micro-aerial vehicles.
34
Holstius, David. "Monitoring Particulate Matter with Commodity Hardware". Thesis, University of California, Berkeley, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3640465.
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Health effects attributed to outdoor fine particulate matter (PM 2.5) rank it among the risk factors with the highest health burdens in the world, annually accounting for over 3.2 million premature deaths and over 76 million lost disability-adjusted life years. Existing PM2.5 monitoring infrastructure cannot, however, be used to resolve variations in ambient PM2.5 concentrations with adequate spatial and temporal density, or with adequate coverage of human time-activity patterns, such that the needs of modern exposure science and control can be met. Small, inexpensive, and portable devices, relying on newly available off-the-shelf sensors, may facilitate the creation of PM2.5 datasets with improved resolution and coverage, especially if many such devices can be deployed concurrently with low system cost.
Datasets generated with such technology could be used to overcome many important problems associated with exposure misclassification in air pollution epidemiology. Chapter 2 presents an epidemiological study of PM2.5 that used data from ambient monitoring stations in the Los Angeles basin to observe a decrease of 6.1 g (95% CI: 3.5, 8.7) in population mean birthweight following in utero exposure to the Southern California wildfires of 2003, but was otherwise limited by the sparsity of the empirical basis for exposure assessment. Chapter 3 demonstrates technical potential for remedying PM2.5 monitoring deficiencies, beginning with the generation of low-cost yet useful estimates of hourly and daily PM2.5 concentrations at a regulatory monitoring site. The context (an urban neighborhood proximate to a major goods-movement corridor) and the method (an off-the-shelf sensor costing approximately USD $10, combined with other low-cost, open-source, readily available hardware) were selected to have special significance among researchers and practitioners affiliated with contemporary communities of practice in public health and citizen science. As operationalized by correlation with 1h data from a Federal Equivalent Method (FEM) β-attenuation data, prototype instruments performed as well as commercially available equipment costing considerably more, and as well as another reference instrument under similar conditions at the same timescale (R2 = 0.6). Correlations were stronger when 24 h integrating times were used instead (R2 = 0.72).
Chapter 4 replicates and extends the results of Chapter 3, showing that similar calibrations may be reasonably exchangeable between near-roadway and background monitoring sites. Chapter 4 also employs triplicate sensors to obtain data consistent with near-field (< 50 m) observations of plumes from a major highway (I-880). At 1 minute timescales, maximum PM2.5 concentrations on the order of 100 μg m–3 to 200 μg m–3 were observed, commensurate with the magnitude of plumes from wildfires on longer timescales, as well as the magnitude of plumes that might be expected near other major highways on the same timescale. Finally, Chapter 4 quantifies variance among calibration parameters for a large sample of the sensors, as well as the error associated with the remote transfer of calibrations between two sufficiently large sets (± 10 % for n = 12). These findings suggest that datasets generated with similar sensors could also improve upstream scientific understandings of fluxes resulting from indoor and outdoor emissions, atmospheric transformations, and transport, and may also facilitate timely and empirical verification of interventions to reduce emissions and exposures, in many important contexts (e.g., the provision of improved cookstoves; congestion pricing; mitigation policies attached to infill development; etc.). They also demonstrate that calibrations against continuous reference monitoring equipment could be remotely transferred, within practical tolerances, to reasonably sized and adequately resourced participatory monitoring campaigns, with minimal risk of disruption to existing monitoring infrastructure (i.e., established monitoring sites). Given a collaborator with a short window of access to a reference monitoring site, this would overcome a nominally important barrier associated with non-gravimetric, in-situ calibration of continuous PM2.5 monitors. Progressive and disruptive prospects linked to a proliferation of comparable sensing technologies based on commodity hardware are discussed in Chapter 5.
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Allen, Martin. "Profile analysis of bulk particulate material". Thesis, University of Nottingham, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357096.
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Mackay, Neil G. "Simulations of earth's local particulate environment". Thesis, University of Kent, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240434.
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Leetham, R. P. "Continuous cementation in particulate electrolytic cells". Thesis, University of Newcastle Upon Tyne, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355839.
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Healey, Katherine. "The genotoxicity of urban particulate matter". Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422089.
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Bramwell, Vincent Warren. "Particulate delivery systems in vaccine design". Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.407749.
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Osmundsen, Sugrunn Anne. "Particulate strategies for improving oral bioavailability". Thesis, University of Strathclyde, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417335.
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Lazidis, Aristodimos. "Stabilisation of foams by particulate structures". Thesis, University of Birmingham, 2017. http://etheses.bham.ac.uk//id/eprint/7304/.
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This thesis aims to advance the knowledge on the effect that particulates of dairy (whey protein) and non-dairy (tricalcium phosphate) origin have on the stability of foams. The production of whey protein particulates was investigated via two separate routes. The first involved the preparation of whey protein gels which were subsequently freeze dried and then milled to powders. The second made use of the technology of creating fluid gels, used so far with polysaccharide based colloids, to fabricate whey protein fluid gels. In both cases, the systems obtained demonstrated the ability to create foams with significantly higher stability than native whey protein. Fluid gel systems were identified as the most industrially relevant systems and the possibility to produce powder formulations from them was explored via employing two different methods, spray drying and agglomeration drying. Ultimately, the design of hydrophobic particles from non-dairy food grade materials and their ability to adsorb on the air/water interface and stabilise foams was studied. The hydrophobicity of tricalcium phosphate (TCP) particles was modified by electrostatically binding ionic surfactant (lauric arginate ether - LAE) molecules on its surface. The behaviour of the particle-surfactant systems in terms of foaming ability and stability was investigated.
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Su, Jia S. M. Massachusetts Institute of Technology. "Biological and particulate contaminants in interfaces". Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120444.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 63-70).
The transport of biological, chemical, or particulate contaminants shapes disease transmission, chemical spills, climate, ecology, and bio-hazard risks. Yet, little is understood on the mechanisms controlling droplet formation and selection of droplet sizes and contamination levels from a contaminated water bulk. Bubbles play a critical role in shaping this transfer of chemicals, particulates, and biological organisms from water to air. They surface, and eventually burst, emitting myriads of droplets into the air. Despite recent progress in our understanding of bubble formation and bursting at the air-water interface, the factors selecting the loads that they carry and emit into the air remain unknown in part due to limitation in direct measurements. In this thesis, we discuss a method of direct visualization and quantification of particulates contained in contaminated bubble films at interfaces. The calibration of this method is key to progress in our understanding of particulate transport from water to air. In particular, although our method allows to reveal contaminants within films via the appearance of spots, the exact link between the size of such spots and the size of the original particles or organisms, their shape, wetting, and the size of the film remain unexplored. In this thesis, we performed a series of systematic measurements and calibrations using bacteria, particles, and rods of various sizes and wetting properties to calibrate the spot sizes observed on contaminated bubbles and films. We rationalized the dependencies observed using a combination of optical ray-tracing and modelling of film distortion in the presence of contaminant. Our results have important implications for in situ study of particles and bacterial communities within large scale complex interfaces.
by Jia Su.
S.M.
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Vincent, Keith John. "Atmospheric particulate matter and historic buildings". Thesis, Middlesex University, 1993. http://eprints.mdx.ac.uk/13435/.
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Atmospheric particulate matter, along with gaseous and precipitation pollutants, were collected close to three historic buildings; Lincoln Cathedral, Bolsover Castle and Wells Cathedral, in order to estimate the amount of sulphur and nitrogen deposited onto each. Results obtained showed that the gaseous dry deposition of both sulphur and nitrogen was the main deposition pathway at Lincoln and Bolsover, whereas as a result of high precipitation amounts the wet deposition pathway was the most significant at Wells. At each sampling site the amount of sulphur and nitrogen deposited as dry particulate matter was relatively insignificant. Estimated washout values for both SO² and SO²⁻, indicated that the former provided approximately 80% of the sulphur in precipitation arriving at the building surfaces. The important role of the gas was reinforced by the significant correlation between the sulphur level in precipitation and sulphur dioxide. The concentration of sulphur in precipitation was found to decrease at high precipitation volumes, whereas the nitrogen concentration was unaffected by precipitation volume. A high sulphate to sulphur dioxide concentration ratio during the summer months was indicative of photochemical oxidation processes. Conversely, during the winter months the relatively low sulphate to sulphur dioxide concentration ratio suggested that sulphate and sulphur dioxide were released from common sources. Multivariate statistical techniques, comprising principal component analysis and multiple regression analysis, were used to infer characteristics about the origin of the constituent parts of the collected particulate matter. In general, three sources of material; secondarily formed particulate matter, sea-salt and crustal material, were estimated to contribute to the collected particulate matter.
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Payne, Simon Daniel. "Experimental studies of diesel particulate filtration". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610170.
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Roth, Jake. "Bleed air oil contamination particulate characterization". Thesis, Kansas State University, 2015. http://hdl.handle.net/2097/19022.
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Master of ScienceDepartment of Mechanical and Nuclear Engineering
Mohammad H. Hosni
Byron W. Jones
Gas turbine engine oil is contaminating the bleed air of an aircraft with enough frequency and intensity that health concerns are of public interest. While previous work measured micro particles and used only a simulator, this work mainly consists of measurements in the nanoparticle and ultrafine range using both the simulator and two different gas turbine engines. No previous research has been conducted using working jet engines to simulate a bleed air system and characterize the oil particulate contamination. Oil was injected into a bleed air simulator and an Allison 250 CC18 turbine engine in order to observe the particle size distributions resulting from thermal degradation and was measured with three particle sizing counters and an FTIR. The aerosol size distributions are given for various temperature and pressure ranges consistent with the process conditions associated with the bleed air in a commercial aircraft. Particle sizes of approximately 80nm to 100nm were observed at temperatures over 200°C while particles similar to injection distributions and smaller than measureable size were observed at lower power settings. Temperature is thought to be the controlling factor affecting particle size above 200°C while blade shear is likely the dominant factor for lower temperatures. The bleed air simulator produced results similar to the gas turbine engine results at higher temperatures, but did not replicate the size characteristics at lower temperatures. The observed particles are ultrafine and situated in the size range that may impact health safety more than larger particles.
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Zhang, Kefeng. "Flow of particulate solids in silos". Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/13254.
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The experimental study was conducted to explore the flow behaviour of particulate solids in silos and to provide the experimental data for the theoretical work. Silo discharge tests using polypropylene pellets in a half cylindrical model silo were conducted under different discharge eccentricities. In addition, some experimental data from a research project on a full scale silo at the University of Edinburgh were also analysed and used in this thesis. In these tests, the main observations relating to flow were the residence times of the markers seeded in the solid during filling (residence time is the time a particle takes to move from its initial position to the outlet). The top surface profile was also measured at regular intervals during discharge. The residence time measurements are analysed using several approaches to infer the approximate location of the flow channel boundary in both silos. These techniques demonstrate how residence time measurements can be used to infer the flow patterns in silo discharge. In addition to the above, the transparent front wall in the half cylindrical model silo enabled a record to be made of the development of the flow channel boundary and the trajectories of individual particles. This data provided further insight into the complex flow patterns. The direct measurements of the changing flow channel boundary are also used in the thesis to evaluate the dilation of the solid which occurred in the flowing material. The dilation, or decrease in the bulk density, is believed to play a significant role in determining the solids flow pattern. The theoretical work presented starts with the development of a simple engineering model to predict solids flow in funnel flow silos. This model uses the kinematic theory for steady state flow, subject to simple assumptions concerning the top surface profile, top surface flow geometry and particle trajectory. The flow of iron ore pellets in the full scale silo and polypropylene pellets in the model silo during concentric emptying are predicted using the simple engineering model. The predictions for both silos are plausible and are in good agreement with the experimental observations.
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Price, Philip Daniel. "Direct injection gasoline engine particulate emissions". Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:35c0d6bf-bde3-4ef0-a87e-4af89a94b16f.
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Direct fuel injection technology is increasingly being applied to the spark ignition internal combustion engine as one of the many actions required to reduce the CO2 emissions from road transport. Whilst the potential for CO2 reductions is compelling, the technology is not without disadvantages. Early examples typically emitted over an order of magnitude more Particulate Matter (PM) than vehicles with conventional spark ignition engines. Consequently, future revisions to European and North American exhaust emissions legislation are likely to regulate the particulate emissions from vehicles with direct injection gasoline engines. This thesis undertakes to investigate a) instrumentation capable of simultaneously resolving the number concentration and size distribution of particles in the 5-1000 nm size range and b) the factors affecting the PM emissions from spark ignition engines with direct fuel injection. The first objective is achieved by evaluation and comparison of a differential mobility spectrometer; photo-acoustic soot sensor; condensation particle counter and electrical low pressure impactor. To address the second question, a differential mobility spectrometer is applied to quantify the PM emissions from a number of direct injection gasoline engines, together with investigation of their dependence on various calibratable parameters, operating temperature and fuel composition. The differential mobility spectrometer showed good agreement with the other more established instruments tested. Moreover, it exhibited a faster time response and finer resolution in particle size. The number weighted size distribution of the PM emitted was typically lognormal with either one or two modes located between 20 and 100 nm. Chemical analysis of PM samples showed the presence of elemental carbon, volatile organic material and sulphates. Transient PM measurements enabled short time-scale events such as mode switching between homogeneous and stratified mixture preparation to be identified. PM number concentrations in stratified mode exceeded those in homogeneous mode by a factor of 10-100. Dynamometer based experiments showed that PM emissions increase for rich air fuel ratios, retarded fuel injection and advanced ignition events. They also demonstrated a strong dependence on fuel composition: the highest PM emissions were measured with an aromatic fuel, whereas blending alcohols such as methanol or ethanol tended to suppress PM emissions, particularly in the accumulation mode size range. These measurements are amongst the first of their kind and demonstrate the applicability of the differential mobility spectrometer to the measurement of ultra-fine particulate emissions from engines with direct fuel injection systems. Numerous explanations are put forward to describe the data obtained, together with suggestions for future work on PM control and abatement.
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Dickerson, David Stanley. "Particulate monitoring in environmental pollution assessment". Thesis, University of Bristol, 2004. http://hdl.handle.net/1983/a66c8b21-c61f-4da7-bca8-5bd7547198b3.
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Jurinski, Joseph Bernard Jr. "Geochemical Investigations of Respirable Particulate Matter". Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30632.
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Over the course of our lives we are exposed to airborne particulate matter in the workplace, home, and environment that results in the deposition of millions of particles in the lung. These exposures may result in disease if they are significant enough. The potential for harmful exposure depends in part on the dust's biodurability and the bioavailability of harmful constituents derived from the particles. A mixed flow reactor was used to evaluate two applications of geochemical methods to characterize the behavior of inhaled particles in the body. Dissolution rates of a well-characterized sample of powdered talc were measured in solvents that mimic fluids found in the human lung. These studies showed that variation of solvent chemistry, including the addition of organic chelators and proteins at intercellular fluid concentrations, does not markedly affect the measured dissolution rate of talc at 37 degrees Celcius and the data further indicate that the dissolution mechanism for talc in aqueous solutions is independent of pH over a range of pH from 2 to 8. The dissolution rate, determined by measuring the silicon release rate per unit surface area of talc is 1.4 (+/- 1.0) x 10-11 mol Si/(m2 -sec). A geometric shrinking particle model using this dissolution rate predicts an estimated lifetime (upper limit) of approximately 8 years for a 1 micron talc particle under pulmonary conditions. Talc dissolves considerably faster than quartz, but slower than chrysotile and olivine in the body. These data can be used to place constraints on the role of particle dissolution in the disease models associated with airborne respirable particulate matter.
Secondly, the bioavailability of As and Cr was determined from a sample of coal fly ash from an eastern U.S. power plant. The time-release profiles of As and Cr were determined for these materials in physiologically-based solvents and incorporated into a toxicokinetic model to predict the exposure potential to As and Cr from occupational exposures to the coal fly ash. Predicted occupational exposure contributions from the ash relative to total environmental exposures were insignificant. The exposure predicted from the geochemical approach was compared with results observed in a cohort occupationally exposed to coal fly ash and found to be within one order of magnitude of the response of the occupational cohort. These results support the application of geochemical techniques to evaluate exposures to complex respirable materials.Ph. D.
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Bains, G. S. "Mechanisms of drying of particulate slurries". Thesis, Aston University, 1990. http://publications.aston.ac.uk/15270/.
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The literature on the evaporation of pure liquid drops and the drying of drops of solutions and slurries has been reviewed with particular reference to spray drying. A 0.1-0.2 mm glass filament-thermocouple was constructed and used to study simultaneously, heat and mass transfer from a single suspended drop placed in a humidity and temperature controlled, 28 mm OD vertical wind tunnel. Heat conduction through the filament was minimised eg at 100¦C it accounted for only 9.3% of the total heat transferred to a drop. Evaporation of single water drops was also studied in a 101 mm OD vertical wind tunnel. The Nusselt number was found to be a function of the Reynolds, Prandtl and Transfer number over an air temperature range of 17¦C to 107¦C. The proposed correlation is: Nu = 2+(-12.96B+0.76)Re¦-5Pr0-33 Experimental drying studies were carried out on single suspended 1 to 2.5 mm diameter drops of aqueous sodium sulphate decahydrate, sodium chloride, potassium sulphate, copper sulphate and sodium acetate solutions and slurries at temperatures of 20¦C to 124¦C. Dried crusts were examined by Scanning Electron Microscopy. The drying history of any material depended upon the nature of the crust formed. Sodium acetate formed a non-rigid skin prior to the formation of a rigid crust. A modified receding evaporation interface model was proposed for the drying of solutions and slurries. This covered both the constant rate period prior to crust formation and the subsequent falling rate period. The model was solved numerically for the variation in core temperature, drop weight and crust thickness. Good agreement was obtained between model predictions and experimental results for materials forming rigid crusts i.e. sodium sulphate decahydrate, sodium chloride, potassium sulphate and copper sulphate. However, the drying histories of drops of 10-20% weight initial concentration sodium acetate were unpredictable since formation of a non-rigid skin deviated from the model assumption of a rigid outer surface. At higher initial concentrations (40% weight) where a rigid crust was formed for sodium acetate, good agreement was obtained between experimental results and model predictions. Single suspended drop studies are concluded to provide a valuable insight into the drying mechanisms of specific solutions and slurries.