Dissertations / Theses on the topic 'Serous fluids'

La Décomposition Modale Empirique (Empirical Mode Decomposition - EMD) ou la Transformation de Hilbert-Huang (HHT) est une nouvelle méthode d'analyse temps-fréquence qui est particulièrement adaptée pour des séries temporelles nonlinéaires et non stationnaires. Cette méthode a été proposée par NE. HUANG. il y a plus de dix ans. Pendant les dix dernières années, plus de 1000 articles ont appliqué cette méthode dans le cadre de diverses applications ou domaines de recherche. Dans cette thèse, nous appliquons cette méthode à des séries temporelles de turbulence, pour la première fois, et à des séries temporelles environnementales. Nous avons obtenu comme résultat le fait que la méthode EMD correspond à un banc de filtre dyadique (ou quasi-dyadique) pour la turbulence pleinement développée. Pour caractériser les propriétés intermittentes d'une série temporelle invariante d'échelle, nous avons généralisé l'analyse spectrale de Hilbert-Huang classique à des moments d'ordre arbitraire $q$, pour effectuer ce que nous avons appelé ``analyse spectrale de Hilbert d'ordre arbitraire''. Ceci fournit un nouveau cadre pour analyser l'invariance d'échelle directement dans un espace amplitude-fréquence, en estimant une intégrale marginale d'une pdf jointe $p(\omega,\mathcal{A})$ de la fréquence instantanée $\omega$ et de l'amplitude $\mathcal{A}$. Nous validons tout d'abord la méthode en analysant des séries temporelles de mouvement Brownien fractionnaire, et en analysant des séries temporelles multifractales synthétiques, en tant que modèle respectivement de processus monofractals et multifractals. Nous comparons les résultats obtenus avec la nouvelle méthode, à l'analyse classique utilisant les fonctions de structure: nous trouvons numériquement que la méthodologie utilisant l'approche de Hilbert fournit un estimateur plus précis pour le paramètre d'intermittence. Avec une hypothèse de stationarité, nous proposons un modèle analytique pour la fonction d'autocorrélation des incréments de séries temporelles de vitesse $\Delta u_{\ell}(t)$, où $\Delta u_{\ell}(t)=u(t+\ell)-u(t)$, et $\ell$ est l'incrément temporel. Dans le cadre de ce modèle, nous prouvons analytiquement que, si une loi de puissance est valide pour la série d'origine, la position minimisant la fonction d'autocorrélation de la variable d'origine est égale exactement au temps de séparation $\ell$ lorsque $\ell$ appartient à la zone invariante d'échelle. Ce modèle prédit une loi de puissance pour la valeur minimum, comportement vérifié par une simulation de mouvement Brownien fractionnaire et à partir de données expérimentales de turbulence. En introduisant une fonction cumulative pour la fonction d'autocorrélation, la contribution en échelle est alors caractérisée dans l'espace de fréquence de Fourier. Nous observons que la contribution principale à la fonction d'autocorrélation provient des grandes échelles. La même idée est appliquée à la fonction de structure d'ordre 2. Nous obtenons que celle-ci est également fortement influencée par les grandes échelles, ce qui montre que ceci n'est pas une bonne approche pour extraire les exposants invariants d'échelle d'une série temporelle lorsque les données sont caractérisées par des grandes échelles énergétiques. Nous appliquons ensuite cette méthodologie Hilbert-Huang à une base de données de turbulence homogène et presque isotrope, pour caractériser les propriétés multifractales invariantes d'échelle des série temporelles de vitesse en turbulence pleinement développée. Nous obtenons un comportement invariant d'échelle pour la pdf jointe $p(\omega,\mathcal{A})$ avec un exposant proche de la valeur de Kolmogorov. Nous estimons les exposants $\zeta(q)$ dans un espace amplitude-fréquence, pour la première fois. L'hypothèse d'isotropie est testée échelle par échelle dans l'espace amplitude-fréquence. Nous obtenons que le rapport d'isotropie généralisé décroit linéairement avec le moment $q$. Nous effectuons également l'analyse d'une série temporelle de température (scalaire passif) possédant un effet de rampe marqué (ramp-cliff). Pour ces données, l'approche traditionnelle utilisant les fonctions de structure ne fonctionne pas. Mais la nouvelle méthode développée dans cette thèse fournit un net régime invariant d'échelle jusqu'au moment $q=8$. Les exposants $\xi_{\theta}(q)-1$ sont très proches des exposants $\zeta(q)$ obtenus par l'approche des fonctions de structure pour la vitesse longitudinale. Nous nous intéressons ensuite à l'auto-similarité étendue (Extended Self Similarity - ESS) dans le cadre Hilbert-Huang. En ce qui concerne la méthode ESS, qui est devenue classique en turbulence, nous adaptons l'approche pour le cas Hilbert-Huang dans un espace de fréquence, et nous constatons que le modèle lognormal, avec un coefficient adéquat, fournit une très bonne estimation des exposants invariants d'échelle. Finalement nous appliquons la nouvelle méthodologie à des données environnementales: des débits de rivières, et des données de turbulence marine dans la zone de surf. Dans ce dernier cas, la méthode ESS permet de séparer les ondes de vent de la turbulence à petite échelle.

District heating has a long standing tradition in Sweden and today it is the most common way of producing and transporting heat. A District heating system (DH system) is divided into three parts: a production facility, distribution network (DH network) and one more heat stations. The heat produced in the facilities is distributed to the customers via a heat transfer medium, usually water (DH water), in piping networks that make up the DH network. The heat is transferred to the customers via the heat exchanger at which point they can use it as heated tap water or for heating purposes. The DH networks are often constructed in steel as it is cheap and a relatively resistant material. However it has the disadvantages of corrosion and expansions when it is exposed high temperatures which lead to damages in the DH network resulting in loss of the DH water, this is an unavoidable occurrence in any DH network. This results in addition of pollutants by leakages into the DH network or with the water that is used to compensate for the losses. The pollutants cause further corrosion, leading to metal contamination, and more damages on the DH network meaning there is a continuous degradation. Therefore various treatments are used to clean and ascertain an acceptable chemical environment in the DH systems. These treatments are effective but not at a level which is required so many chemicals are used to enhance the treatment of the water. Some of these are known to be toxic to humans and water ecosystems. As leakages are abundant and often end up in the WWTPs of the concerned municipality, which often have troubles with disturbances of the biological treatment, it was decided that an assessment of the toxic effects that DH water pose on activated sludge was to be investigated. This was done by testing water from two DH networks, Växjö and Kalmar, on the same activated sludge obtained from Tegelviken WWTP in Kalmar. A respirometric bioassay approach established by the Organization for Economic Co-operation and Development (OECD), OECD standard 209; OECD Guidelines for the Testing of Chemicals was used with changes made to exposure and measuring time as this decrease the risk of misinterpretation of the results. A dilution series using different concentrations (6.25%, 25% and 100%) of DH water was tested and compered to a blank control samples containing only activated sludge. Assessment of toxicity on total oxidation, oxidation carbon and oxidation of nitrogen was made. To get some idea of what might cause toxic effect samples of the waters was sent to outside laboratories for analyses of metals. The result from the bioassay and metal analysis was used to formulate risk factors associated with a DH water spill and exposure to WWTPs. It was found that both DH waters have a significant inhibition on nitrification in WWTPs. The DH water from Kalmar exhibited similar toxicity dynamics, roughly 20% inhibition, despite large differences in concentration. The DH water from Växjö showed a negative correlation between an increase in concentration of DH water and toxicity, 74% for the lowest concentration and 11% for the highest. The metal analysis concluded that there was no abundance of metal contamination which led to the inference that toxicity is probably caused by the chemicals used for treatment. This poses a great risk for the Baltic Ocean as many WWTPs release their treated water directly into water courses with a short detention time before reaching the sea.

Le "climat" à l'intérieur d'une serre dépend de son aération. Le processus d'aération est complexe, il participe à l'essentiel des échanges de chaleur et de masse avec l'extérieur, et sa maîtrise permet donc de contrôler les paramètres physiques tels que la température, l'humidité, ou les concentrations de gaz comme le CO2 par exemple. Ce contrôle est essentiel pour maintenir les plantes dans des conditions métaboliques favorables (respiration, photosynthèse, transpiration) et dans un état sanitaire satisfaisant.
La ventilation naturelle est le système le plus économique pour réguler le microclimat interne de la serre. Néanmoins, elle n'offre qu'un contrôle limité sur l'écoulement d'air dans la serre et reste difficile à maîtriser.
Cette étude contribue à l'analyse et à la modélisation des phénomènes mis en jeu dans l'aération naturelle des serres en verre, de grande portée, habituellement utilisées en culture ornementale (plantes en pots), sous climat tempéré, tel qu'en Anjou. Deux approches complémentaires incluant expérimentation in situ et modélisation mathématique du climat distribué sont mises en œuvre.
Des campagnes de mesures ont été menées à l'intérieur d'une serre de production et dans son environnement immédiat sous conditions réelles de culture ornementale. Des données météorologiques : température de l'air, vitesse et direction du vent, rayonnement solaire et atmosphérique, ont été collectées. L'ensemble de ces mesures constitue un jeu de données conséquent destiné à fournir les entrées du modèle numérique. Parallèlement à ces mesures, nous avons systématiquement procédé à des mesures du taux de renouvellement d'air qui ont été utilisées pour valider le modèle.
Un modèle numérique a été mis en œuvre. Il s'appuie sur un code de mécanique des fluides numérique (Computational Fluid Dynamics). Ce code permet de prédire les champs de vitesses et de températures à l'intérieur de la serre après résolution numérique des équations de base qui régissent les mouvements d'air (équations de Navier-Stokes couplées à l'équation de l'énergie) dans le domaine de calcul considéré. La turbulence, dont l'effet est loin d'être négligeable sous serre, a été modélisée à l'aide d'une fermeture de type k-e. Le taux d'aération a pu être déduit ensuite par résolution d'une équation de transport d'un gaz traceur virtuel. Un module radiatif a été ajouté dans le modèle numérique afin de prendre en compte le rayonnement d'origine solaire et atmosphérique. Ce module résout l'équation des Transferts Radiatifs qui est couplée à l'équation de l'énergie.
Ce modèle « complet » a pu être vérifié et validé pour différentes conditions climatiques. Il a été ensuite utilisé pour analyser l'impact de la configuration des ouvrants sur le climat et sur les flux de chaleur au niveau de la toiture de la serre. Cette analyse a porté non seulement sur la ventilation mais aussi sur l'homogénéité de la distribution des vitesses et des températures dans la serre et notamment au niveau des cultures.
Enfin, des indicateurs d'efficacité de l'aération de la serre sous climat estival ont pu être dégagés pour différentes configurations d'aération (ouverture) et différentes conditions climatiques.

Several industrial, scientific and commercial processes produce open-ended sequences of observations which are referred to as data streams. We can understand the phenomena responsible for such streams by analyzing data in terms of their inherent recurrences and behavior changes. Recurrences support the inference of more stable models, which are deprecated by behavior changes though. External influences are regarded as the main agent actuacting on the underlying phenomena to produce such modifications along time, such as new investments and market polices impacting on stocks, the human intervention on climate, etc. In the context of Machine Learning, there is a vast research branch interested in investigating the detection of such behavior changes which are also referred to as concept drifts. By detecting drifts, one can indicate the best moments to update modeling, therefore improving prediction results, the understanding and eventually the controlling of other influences governing the data stream. There are two main concept drift detection paradigms: the first based on supervised, and the second on unsupervised learning algorithms. The former faces great issues due to the labeling infeasibility when streams are produced at high frequencies and large volumes. The latter lacks in terms of theoretical foundations to provide detection guarantees. In addition, both paradigms do not adequately represent temporal dependencies among data observations. In this context, we introduce a novel approach to detect concept drifts by tackling two deficiencies of both paradigms: i) the instability involved in data modeling, and ii) the lack of time dependency representation. Our unsupervised approach is motivated by Carlsson and Memolis theoretical framework which ensures a stability property for hierarchical clustering algorithms regarding to data permutation. To take full advantage of such framework, we employed Takens embedding theorem to make data statistically independent after being mapped to phase spaces. Independent data were then grouped using the Permutation-Invariant Single-Linkage Clustering Algorithm (PISL), an adapted version of the agglomerative algorithm Single-Linkage, respecting the stability property proposed by Carlsson and Memoli. Our algorithm outputs dendrograms (seen as data models), which are proven to be equivalent to ultrametric spaces, therefore the detection of concept drifts is possible by comparing consecutive ultrametric spaces using the Gromov-Hausdorff (GH) distance. As result, model divergences are indeed associated to data changes. We performed two main experiments to compare our approach to others from the literature, one considering abrupt and another with gradual changes. Results confirm our approach is capable of detecting concept drifts, both abrupt and gradual ones, however it is more adequate to operate on complicated scenarios. The main contributions of this thesis are: i) the usage of Takens embedding theorem as tool to provide statistical independence to data streams; ii) the implementation of PISL in conjunction with GH (called PISLGH); iii) a comparison of detection algorithms in different scenarios; and, finally, iv) an R package (called streamChaos) that provides tools for processing nonlinear data streams as well as other algorithms to detect concept drifts.
Diversos processos industriais, científicos e comerciais produzem sequências de observações continuamente, teoricamente infinitas, denominadas fluxos de dados. Pela análise das recorrências e das mudanças de comportamento desses fluxos, é possível obter informações sobre o fenômeno que os produziu. A inferência de modelos estáveis para tais fluxos é suportada pelo estudo das recorrências dos dados, enquanto é prejudicada pelas mudanças de comportamento. Essas mudanças são produzidas principalmente por influências externas ainda desconhecidas pelos modelos vigentes, tal como ocorre quando novas estratégias de investimento surgem na bolsa de valores, ou quando há intervenções humanas no clima, etc. No contexto de Aprendizado de Máquina (AM), várias pesquisas têm sido realizadas para investigar essas variações nos fluxos de dados, referidas como mudanças de conceito. Sua detecção permite que os modelos possam ser atualizados a fim de apurar a predição, a compreensão e, eventualmente, controlar as influências que governam o fluxo de dados em estudo. Nesse cenário, algoritmos supervisionados sofrem com a limitação para rotular os dados quando esses são gerados em alta frequência e grandes volumes, e algoritmos não supervisionados carecem de fundamentação teórica para prover garantias na detecção de mudanças. Além disso, algoritmos de ambos paradigmas não representam adequadamente as dependências temporais entre observações dos fluxos. Nesse contexto, esta tese de doutorado introduz uma nova metodologia para detectar mudanças de conceito, na qual duas deficiências de ambos paradigmas de AM são confrontados: i) a instabilidade envolvida na modelagem dos dados, e ii) a representação das dependências temporais. Essa metodologia é motivada pelo arcabouço teórico de Carlsson e Memoli, que provê uma propriedade de estabilidade para algoritmos de agrupamento hierárquico com relação à permutação dos dados. Para usufruir desse arcabouço, as observações são embutidas pelo teorema de imersão de Takens, transformando-as em independentes. Esses dados são então agrupados pelo algoritmo Single-Linkage Invariante à Permutação (PISL), o qual respeita a propriedade de estabilidade de Carlsson e Memoli. A partir dos dados de entrada, esse algoritmo gera dendrogramas (ou modelos), que são equivalentes a espaços ultramétricos. Modelos sucessivos são comparados pela distância de Gromov-Hausdorff a fim de detectar mudanças de conceito no fluxo. Como resultado, as divergências dos modelos são de fato associadas a mudanças nos dados. Experimentos foram realizados, um considerando mudanças abruptas e o outro mudanças graduais. Os resultados confirmam que a metodologia proposta é capaz de detectar mudanças de conceito, tanto abruptas quanto graduais, no entanto ela é mais adequada para cenários mais complicados. As contribuições principais desta tese são: i) o uso do teorema de imersão de Takens para transformar os dados de entrada em independentes; ii) a implementação do algoritmo PISL em combinação com a distância de Gromov-Hausdorff (chamado PISLGH); iii) a comparação da metodologia proposta com outras da literatura em diferentes cenários; e, finalmente, iv) a disponibilização de um pacote em R (chamado streamChaos) que provê tanto ferramentas para processar fluxos de dados não lineares quanto diversos algoritmos para detectar mudanças de conceito.

Nesta tese investigou-se os padrões microclimáticos, de fluxos de energia e CO2 em uma floresta em planície de inundação da Ilha do Bananal, com ênfase nos efeitos da inundação sazonal nas variáveis atmosféricas e na produtividade do ecossistema, além de estimativas de fluxos aquáticos evasivos de CO2 e CH4. Para tanto, foram utilizadas técnicas micrometeorológicas de vórtices turbulentos, estimativas de armazenamento vertical de CO2 e dados medidos em uma torre micrometeorológica no período de 2004 a 2014, além de campanhas específicas para medidas de fluxos evasivos. Embora existam ciclos sazonais bem definidos de precipitação, temperatura do ar e umidade na região, controlados pela oferta radiativa, esta não explica diretamente as variações na evapotranspiração quando se busca explicá-la pelo aumento da disponibilidade energética. O particionamento da energia disponível aponta para um domínio do calor latente em comparação ao sensível durante períodos de decaimento do saldo de radiação, configurando um padrão peculiar não reportado na literatura. Os dados de temperatura do ar, precipitação pluviométrica, fluxos turbulentos de CO2 e fluxos energéticos (LE e H) mostraram uma possível influência das secas que ocorreram no lado oeste da região, também neste sítio experimental do leste. Os anos de 2005 e 2010 foram mais quentes, pouco chuvosos e mais secos que os demais anos da série de dados, e em 2010 ocorreu a menor produtividade líquida da estação seca. A inundação mostrou ter um papel importante nos fluxos de CO2, fazendo com que a produtividade bruta, a respiração do ecossistema e a produtividade líquida diminuam, somando-se os efeitos esperados pelo controle radiativo. A produtividade líquida respondeu aos efeitos da inundação semanas antes desta iniciar na torre, persistindo seus efeitos até algumas semanas depois, com a diminuição da produtividade. Já a respiração do ecossistema e a produtividade primária bruta mostraram ser mais sensíveis ao início da estação seca, com uma interrupção no declínio atribuído à inundação, provavelmente devido ao favorecimento da decomposição de matéria orgânica suspensa na água. Os resultados dos fluxos de carbono sugerem uma alta assimilação de CO2 pela floresta, o que requer corroboração através de medidas biométricas, não sendo, contudo, descartada a confiabilidade dos resultados. Os resultados da campanha para medidas de fluxos evasivos mostraram que o rio é uma fonte de CO2 para a atmosfera, e tanto o rio quanto a superfície vegetada atuam como fonte de CH4 para a atmosfera, com maior contribuição da superfície vegetada. As concentrações de metano e carbono na água foram superiores ás amostragens da atmosfera, o que já era esperado conforme os estudos existentes na literatura.
This thesis investigated the microclimate, CO2 and energy fluxes patterns at a forest in floodplain of Bananal Island, with emphasis on the seasonal flooding effects in atmospheric variables and ecosystem productivity, as well as estimates of evasive water CO2 and CH4 fluxes. To carry it out, micrometeorological eddy covariance technique was associated, vertical storage CO2 estimates and measured data in a micrometeorological tower from 2004 to 2014, as well as specific campaigns for evasive fluxes measures. Although there are welldefined seasonal cycles of precipitation, air temperature and humidity in the area controlled by the radiative offer, it does not directly explain the variations in evapotranspiration when seeking for explain it by the increase in energy availability. Partitioning of the available energy points to a latent heat flux domain compared to sensible heat flux during net radiation decay periods, showing a peculiar pattern not reported in the literature. The data air temperature, rainfall, eddy CO2 and energy fluxes (LE and H) showed a possible influence of droughts that occurred on the west side of the region, in this experimental site from the east. The years 2005 and 2010 were warmer, little rainy and drier than the other years of the data series, and in 2010 had the lowest net productivity of the dry season. The flood was shown to have an important role in CO2 streams, causing the gross productivity, ecosystem respiration and the net productivity decrease, adding to the effects expected by the radiative control. The net productivity responded to the effects of flooding weeks before this start in the tower, continuing its effects until a few weeks later, with decreasing productivity. Already ecosystem respiration and gross primary productivity proved to be more sensitive to early dry season, with an interruption in the decline attributed to flooding, probably due to favoring the decomposition of organic matter suspended in the water. The results of the carbon fluxes suggest a high CO2 assimilation by forest, which requires corroboration through biometric measurements and are not, however, ruled out the reliability of the results. The results of the campaign to evasive flux measurements showed that the river is a CO2 source to the atmosphere, and both the river and the vegetated surface act as a CH4 source to the atmosphere, with a greater contribution of the vegetated surface. Methane and carbon concentrations in the water were higher ace sampling the atmosphere, which was expected as existing studies in the literature.

Questa tesi ricostruisce il contributo di Francesco Maria Grimaldi alla comprensione del fenomeno di diffrazione, da lui sperimentalmente studiato per la prima volta nella seconda metà del Seicento. Il primo capitolo di questo elaborato vuole mostrare i contributi offerti da Grimaldi all’astronomia e alla geodesia in collaborazione con Ricciòli, gesuita e astronomo bolognese, ed anche il rapporto tra scienza e fede, in particolare tra i Gesuiti e l’Università di Bologna. Il secondo capitolo è focalizzato sul De lumine, opera postuma di Grimaldi, e sui due esperimenti riguardanti la diffrazione ivi contenuti. Il terzo capitolo viene dedicato alla storia della diffrazione analizzando la trattazione che ne fecero gli scienziati dopo Grimaldi: si parte da Newton e dalla sua visione corpuscolare della luce per arrivare ad Huygens, Young e Fresnel e all’elaborazione della teoria ondulatoria, che permette di spiegare correttamente il fenomeno della diffrazione.

L'objectif principal de cette thèse est la caractérisation des dynamiques hautes fréquance en milieu côtier et en particulier leurs extrêmes, par l'intermédiaire de l'étude de série temporelle biogéochimiques à long terme enregistrées par des systèmes automatisés. Les bases de données hautes fréquences utilisées dans cette étude proviennent majoritairement du programme MAREL, qui a été mise en oeuvre par l'IFREMER. Des séries temporelles basses fréquences provenant des programmes de surveillance du littoral SOMLIT (CNRS, INSU) et SRN (Ifremer) sont mises à contribution pour appuyer l'importance des systèmes automatisés. La méthode EMD (Empirical Mode Decomposition) nous a servi de base dans de nombreuses analyses pour étudier ces séries temporelles. Nous avons aussi utilisé des méthodes plus classiques empruntées aux domaines de l'analyse numérique et de la turbulence. Cette études se décompose en 3 parties, et plusieurs annexes. Les matériels et méthodes sont présentés dans la première partie. Dans la seconde partie, la méthode EMD nous a permis de mettre en avant les fortes fluctuations contenues dans les blooms, ainsi que de mener des analyses spectrales grâce à un couplage avec la transformée de Hilbert. L'analyse en composante principale (ACP) a mis en avant les principaux forçages exercés sur la production primaire et les profils de température SOMLIT laissent supposer un impact de la stratification sur l'intensité des blooms. Dans la troisième partie, nous avons mené une étude comparative entre les données basses fréquences et hautes fréquences. Et deux méthodes de cross-corrélation (TDIC et co-spectre) nous ont permis de définir une échelle caractéristique de transition entre les températures de la Manche occidentale et orientale. En annexe, nous avons testé la robustesse de différentes méthodes d'analyses spectrales quant au manque de données dans les séries temporelles, qui est un problème inhérent aux bases de données enregistrées par des systèmes automatisés, et nous avons reproduit un article qui est en cours de soumission
The main objective of this thesis is the characterization of high frequency dynamics in coastal areas and in particular their extremes, through the study of long-term biodeochemical time series registered by automated systems. The majority of high-frequency data sets used in this study came from MAREL program. The low-frequency time series from coastal monitoring programs SOMLIT (CNRS, INSU) and SRN (Ifremer) are employed to support the importance of automated systems. The EMD (Empirical Mode decomposition) method has provided a basis for us to study several of these time series. We also have used some methods more classical borrowed from numerical analysis field and turbulence. This study is organized in three chapters, and several appendices. The first chapter is devoted to the material and method. In the second chapter, using the EMD method we have highlighted the strong fluctuations contained in the blooms, and we have performed spectral analyzes. The principal component analysis (PCA) highlighted the main forcing exerted on primary production and SOMLIT temperature profiles suggest an impact of stratification on the intensity of blooms. In the third chapter, we conducted a comparative study between low-frequency and high-frequency data. Two cross-correlation methods (TDIC and co-spectra) allowed us to define a characteristic transition scale between the temperatures of the western and eastern English Cahnnel. In appendices we tested the robustness of different spectral analysis methods about the missing data in the time series, which is an underlying problem in the database registered by automated systems, and we reproduce a paper, which is under submission

Bibliography: leaves 77-78
78 leaves : ill. (some col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1986

碩士
國立中山大學
海洋地質及化學研究所
88
Abstract The research was conducted as a part of the phase III of the KEEP(Kuroshio Edge Exchange Processes)program. Two strings of sediment traps were deployed simultaneously: one near the outlet of North Mien-Hua Canyon (T15), and the other at the south rim of the South Okinawa Trough (T16). The purposes are to collect settling particulates at various depths for the studies of temporal and spatial variations of the particulate flux, 210Pb activity, 210Pb flux and size distribution. The particulate fluxes showed synchronous variations among the traps deployed at different depths of the same site. In general, the particulate flux in the marginal sea areas increases with depth but the maximum values may be at the mid-depth rather than at the deepest trap and remain so for the entire mooring period as observed at T15 and T16. Unusually high particulate fluxes could occur within the same period, probably reflecting an episodic event, such as typhoon or rain storm. 210Pb activity measured from different depths at T15 and T16 increases generally with depth along with the increase of the particulate flux toward the bottom. The temporal variation of 210Pb activity is generally smaller than that of the particulate flux in terms of relative amplitude. At the outlet of the canyon, T15, the temporal mean particulate flux of each trap ranged from 0.16 to 3.3 g/m2/d(a factor of ~ 20), while the mean 210Pb activity of each trap varied from about 98 to 168 dpm/g. At T16 located at the south rim of the South Okinawa Trough, the temporal mean particulate flux ranged from 0.06 to 5.7 g/m2/d(a factor of ~ 100), while the mean 210Pb activity varied from 82 to 192 dpm/g. The particulate 210Pb flux was smaller at T15 than at T16 because T15 has smaller particulate flux. The trapped particulates in the canyon(T1-T3) are mostly silt and sand, while the particulates collected from the Okinawa Trough(T15, T16) are mainly silt and clay. The 210Pb activity of the former is much lower than that of the latter, indicating the enrichment of 210Pb on the fine particulates. As the fine-grained particulates away from landmass have longer residence time in the ambient water, they can scavenge 210Pb more effectively.

碩士
國立中山大學
海洋地質及化學研究所
98
The Kuroshio current (KC) is the major current of the western Pacific Ocean, and its main stream flows northward off the east coast of Taiwan. Since there have been few researches on sinking particle flux in the regime of Kuroshio have been reported, a time-series sediment trap mooring was deployed to investigate the particulate organic carbon (POC) and total nitrogen (TN) and their fluxes at KC station (21o28'' N, 122o11'' E) at depths of 2000 m and 3500 m from April 2008 to December 2009. Results show that, the mass fluxes at 2000 m and 3500 m of mean are 162.3 mg m-2 d-1 and 201.6 mg m-2 d-1, POC fluxes are 3.8 mgC m-2 d-1 and 3.7 mgC m-2 d-1, and TN fluxes are 0.5 mgN m-2 d-1 and 0.5 mgN m-2 d-1, respectively. The averages of POC, TN content and C/N ratio at 2000 m and 3500 m are 2.5 and 1.8 wt%, 0.3 and 0.2 wt%, and 9.27 and 9.21, separately. The depths and temporal variability of POC and TN contents respond closely to bio-degradation and dilution by bottom movement at KC station. Comparison with SEATS station (18o15’N, 115o50’E), the variability of POC and TN compositions and their fluxes at KC are lower than SEATS station. The fluxes of KC exhibit intermittent high-value in the summer, and the fluxes of SEATS in the winter are higher than other seasons. For site comparison and global synthesis, an average e-ratio of 0.08 and the b-value of 0.53 are derived. These results should help a better understanding of POC in the world.

From the nano scale to the macro scale, large models are used to simulate and predict the responses of dynamic systems. The construction and evaluation of such models, often in the form of finite element models, require tremendous computational resources and time. Due to this large computational endeavor, it is paramount to learn as much as possible from the models and their solutions. In this work, analyses and methods for efficiently deriving significant knowledge of damped systems from models and their solutions are presented. Of primary interest to this work is the analysis of damped structures. Damping, the means by which energy is dissipated, often adds an additional layer of complexity to finite element models and any subsequent analyses. This added complexity is due to the relative complexity of many damping models and their accompanying computational burden. Furthermore, on the micro and nano scale, a variety of damping mechanisms, each with their own unique set of physics, may be present. The research presented in this work is organized in two parts. The first part presents methods for deriving knowledge from models and their solutions. Here, the developed methods perform approximate yet highly efficient analysis on the matrices and solution vectors of finite element models. In this work, methods utilizing the Neumann series approximation are presented. These methods efficiently predict how the response of a structure depends on its damping or any other input model parameter. Additionally, a method for analyzing the spatial dependence of damping with the use of loss factor images is presented. Research presented in the second part derives knowledge solely from solutions of models. In this part, it is assumed that the matrices of the models are not available, and therefore analysis is restricted to the solution itself. Here, research is focused on the analyses of structures on the micro and nano scale. Specifically, micro and nano beams surrounded by a viscous compressible fluid are analyzed. The dynamic responses of the structure and the surrounding fluid are analyzed to determine the prominent damping mechanisms. Here, results from 2--Dimensional analytical models and 3--Dimensional finite element models are complemented by experimental measurements to analyze damping due to viscous dissipation and acoustic radiation.

Single Duct Variable Air Volume (SDVAV) systems use series and parallel Fan Powered Terminal Units to control the air flow in conditioned spaces. This research developed a laboratory verified model of SDVAV systems that used series and parallel fan terminal units where the fan speeds were controlled by either Silicon Controlled Rectifiers (SCR) or Electronically Commutated Motors (ECM) motors. As part of the research, the model was used to compare the performance of the systems and to predict the harmonics generated by ECM systems. All research objectives were achieved. The CFD model, which was verified with laboratory measurements, showed the potential to identify opportunities for improvement in the design of the FPTU and accurately predicted the static pressure drop as air passed through the unit over the full operating range of the FPTU. Computational fluid dynamics (CFD) models of typical a FPTU were developed and used to investigate opportunities for optimizing the design of FPTUs. The CFD model identified key parameters required to conduct numerical simulations of FPTU and some of the internal components used to manufacture the units. One key internal component was a porous baffle used to enhance mixing when primary air and induced air entered the mixing chamber. The CFD analysis showed that a pressure-drop based on face velocity model could be used to accurately predict the performance of the FPTU. The SDVAV simulation results showed that parallel FPTUs used less energy overall than series systems that used SCR motors as long as primary air leakage was not considered. Simulation results also showed that series ECM FPTUs used about the same amount of energy, within 3 percent, of parallel FPTU even when leakage was not considered. A leakage rate of 10 percent was enough to reduce the performance of the parallel FPTU to the level of the series SCR system and the series ECM FPTUs outperformed the parallel FPTUs at all weather locations used in the study.