Rozprawy doktorskie na temat „Water stratification”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych rozpraw doktorskich naukowych na temat „Water stratification”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj rozprawy doktorskie z różnych dziedzin i twórz odpowiednie bibliografie.
Belabbassi, Leila. "Examination of the relationship of river water to occurrences of bottom water with reduced oxygen concentrations in the northern Gulf of Mexico". Texas A&M University, 2006. http://hdl.handle.net/1969.1/5018.
Pełny tekst źródłaSangameswaran, Sivaramakrishnan. "Water quality modeling of a storm water channel". ScholarWorks@UNO, 2003. http://louisdl.louislibraries.org/u?/NOD,52.
Pełny tekst źródłaTitle from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering"--Thesis t.p. Vita. Includes bibliographical references.
Hermansson, Roger. "Short term water heat storage : an experimental investigation of thermal stratification". Licentiate thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 1989. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17844.
Pełny tekst źródłaAiken, Anne M. "The effects of seasonal change, impoundment, and stratification on trihalomethane precursors". Thesis, This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-11072008-063149/.
Pełny tekst źródłaSmyth, Mervyn A. "Design and development of a heat retaining integrated collection/storage solar water heater". Thesis, University of Ulster, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264693.
Pełny tekst źródłaWestlake, P. C. "Interfacial and internal waves generated by a submerged prolate spheroid". Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242629.
Pełny tekst źródłaBrowne, Richard Gregory. "The effects of hypolimnetic oxygenation on the chemical, physical, and biological properties of a shallow drinking water reservoir". Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23823.
Pełny tekst źródłaMaster of Science
Winsor, Peter. "Studies of dense shelf water, vertical stratification and sea ice thickness of the Arctic ocean /". Göteborg : Department of oceanography, Earth sciences centre, Göteborg university, 2001. http://catalogue.bnf.fr/ark:/12148/cb41081604j.
Pełny tekst źródłaElam, Kevin Patrick. "Effects of a surface circulator on temperature, dissolved oxygen, water velocity, and photosynthetic yield in Falling Creek Reservoir". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/36454.
Pełny tekst źródłaMaster of Science
Armstrong, Peter Michael. "Enhancing the energy storage capability of electric domestic hot water tanks". Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:af140a2c-aab4-4fc9-8709-6f9474079cd5.
Pełny tekst źródłaMyrtrøen, Ole-Jørgen Feiring. "Vertical Stratification in a Ventilated Space : Comparison of Theoretical Predictions to Experimental Results from a Water Scale Model". Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-8841.
Pełny tekst źródłaThis study investigates the behaviour of a vertically distributed source of buoyancy on the vertical stratification in a ventilated space, an important factor for determining indoor comfort when using displacement ventilation. A new theory describing the behaviour of this buoyancy source in a ventilated space was presented previous to this work, but experimental results were required in order to validate the theoretical and numerical modelling. The behaviour of this source of buoyancy on the stratification in a ventilated space is studied for a mechanically ventilated at steady-state and for a linearly stratified environment using salt water in a water scale model. The stratifications were measured using a traversing conductivity probe and then compared to theoretical predictions by numerically solving the plume equations for the new theory in Fortran. High quality measurements were produced, showing excellent repeatability for stratification measurements at steady-state with deviations of less than 1 %. Moreover, the linear stratifications had linear best fits up to R2 = 0.999 by using the double-bucket method. The theoretical predictions of the influence of the vertically distributed source correlate quantitatively with the mechanically ventilated experiments, showing good agreement to the strength of the ambient stratification, the position of the first front and the ventilation flow rate. The experimental results for the determination of the height of a horizontal intrusion of fluid into the linearly stratified environment were severely affected by the occurrence of gravity current at the ceiling of the ventilated space and comparisons to the new theory was not successful because of this. A two-layer stratification is observed where the upper layer had a weakly stratified density profile, instead of the multi-layer stratification predicted by previous researchers in their theoretical model. This discrepancy is due to smoothing and vertical turbulent mixing in the water scale model. It is recommended that the characteristic of the membrane that is used in the water scale model is investigated in relation to the gravity currents for future research.
Filich, Lukasz. "Modeling and Simulation of Thermal Stratification and Mixing induced by Steam Injection through Spargers into Large Water Pool". Thesis, KTH, Fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-170404.
Pełny tekst źródłaKayserilioglu, Yavuz Selim. "Heat Removal From A Large Scale Warm Water Storage". Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605359/index.pdf.
Pełny tekst źródłaknettin Oskay August 2004, 88 Pages A preliminary experimental study was performed in order to investigate the charging and heat removal characteristics of a sensible heat storage. Two sets of experiments were performed at two aspect ratios. Heat removal processes of these two sets were different while the charging processes were similar. In the first set of experiments, after the charging of the storage unit with relatively warm water was complete, heat removal process was started with simple heat exchangers from different elevations within the storage while the charging of the storage unit was continued. In the second set of experiments, after the charging of the storage unit was complete, heat removal from the storage unit was started without further charging of the storage unit. Charging water was fed into the storage from the top of one side and relatively colder water was drained from the bottom of the opposite side. Internal heat exchangers were used for the heat removal. Vertical temperature profile developments during the charging and heat removal periods were investigated. Thermal stratification was observed in all experiments. Heat exchangers extracted heat from different elevations in different experiments and the trend was that more heat can be extracted in upper elevations. Comparable heat can be extracted from the same elevation of lower and higher aspect ratio. Keywords: Sensible Heat Storage, Heat Removal, Thermal Stratification, Warm Water Storage
Arran, Matthew Iain. "Avalanching on dunes and its effects : size statistics, stratification, & seismic surveys". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/278773.
Pełny tekst źródłaWong, Vui-Hong, i n/a. "Finite Element Analysis and Improvement of Impeller Blade Geometry". Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030825.150853.
Pełny tekst źródłaWong, Vui-Hong. "Finite Element Analysis and Improvement of Impeller Blade Geomtery". Thesis, Griffith University, 2003. http://hdl.handle.net/10072/367302.
Pełny tekst źródłaThesis (Masters)
Master of Philosophy (MPhil)
School of Engineering
Full Text
Garrett, Matthew. "Influence of Water Column Stratification and Nutrient Gradients on the Migratory Behavior of the Red Tide Dinoflagellate, Karenia brevis". Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5950.
Pełny tekst źródłaHwang, Du-Hyun Dwayne. "Flow quality measurement based on stratification of flow in nitrogen gas-water and HFC-134a refrigerant-PAG oil two-phase flow systems". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58743.pdf.
Pełny tekst źródłaYang, Yang. "Phytoplankton and Physical Disturbance : Seasonal dynamics in temperate Lake Erken, Sweden". Doctoral thesis, Uppsala universitet, Limnologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-262461.
Pełny tekst źródłaChoffel, Quentin. "La différenciation des masses d'eau à l'intérieur de l'étang : stratification verticale, zonation horizontale, bilan thermique et centre thermique". Thesis, Orléans, 2019. http://www.theses.fr/2019ORLE1167.
Pełny tekst źródłaPonds are at the heart of environmental issues in terms of quality and quantity of water resources. Temperature is an effective indicator in these measurements because of its reactivity and the ability to diffuse the most downstream. The pond is often considered as a black box in studies and the knowledge of its thermal functioning should be the first element in its quantification. In this study, the inclusion of volumes in the thermal analysis of the 1,137,181 original hourly thermal data, through the heat budget, allows to measure and quantify the whole behavior of the ponds, distinct from that of the lakes. The heat budget is a synthetic indicator of all the factors that bring and extract calories from the environment and can be used in its primary objective to measure calorific exchanges within the water body and between the water body and the river environment. The spatial heterogeneity in the zonal aspect of the pond is influenced by the effect of the driving force of the wind or the surrounding environment, the presence of shade or hydrological inputs. A new indicator, the heat center, has been created, taking into account three-dimensional variations in the heat balance, stratification and stability of several areas of the pond in order to quantify the dissociation of water masses within the water body. The integration of thermal zoning opens up new management opportunities to reduce the thermal impact of the pond downstream or to promote the development of certain heat-sensitive fish species. From meteorological data it is possible to anticipate areas of heat expansion whose differences can be significant, measured at more than 3°C on a very small pond related to the shading effect, or at more than 10°C between two sectors of a large multi-block pond under the influence of winds
Rodríguez, Pérez Ivette. "Unsteady laminar convection in cylindrical domains: numerical studies and application to solar water storage tanks". Doctoral thesis, Universitat Politècnica de Catalunya, 2006. http://hdl.handle.net/10803/6689.
Pełny tekst źródłaSe presenta la metodología seguida para la resolución de las ecuaciones gobernantes de la transferencia de calor y dinámica de fluidos en coordenadas cilíndricas, mostrando las principales particularidades de su discretización para este tipo de geometrías y se detalla el tratamiento realizado para resolver estas singularidades dentro del código numérico. Posteriormente, se expone la metodología para la solución de flujos transitorios e incompresibles y se realiza un riguroso proceso de verificación del código y las soluciones numéricas obtenidas.
Esta metodología se aplica al estudio del comportamiento de los tanques de almacenamiento de energía estratificados. Un aspecto básico del funcionamiento de estos equipos es la calidad de la energía almacenada. Esta calidad viene determinada por el grado de estratificación térmica, en la cual influyen diferentes factores como la mezcla que ocurre debido a las corrientes de fluido que entran durante los procesos de carga y descarga térmica y también debido al intercambio de calor con el ambiente. En este sentido, en este trabajo se analiza la estratificación térmica para diferentes condiciones de trabajo y configuraciones por medio de las simulaciones numéricas multidimensionales. Para medir el grado de estratificación se han tenido en cuenta diferentes parámetros y como resultado del estudio, se propone un parámetro adimensional basado en un análisis exergético. Esta exergía adimensional ha permitido comparar el funcionamiento de los tanques en las diferentes situaciones analizadas y se ha mostrado útil para cuantificar la calidad de la energía almacenada.
Por otra parte, se estudia el comportamiento térmico de los tanques de almacenamiento durante su modo de operación estático y considerando las pérdidas de energía al ambiente. Este estudio tiene como objetivo fundamental caracterizar el proceso de enfriamiento del fluido en tanques que forman parte de sistemas solares térmicos para el rango de bajas y medianas temperaturas. Se presenta la metodología seguida para el análisis, desde la identificación de los números adimensionales que definen el problema, la formulación de un modelo zonal para la predicción del comportamiento térmico, el estudio paramétrico llevado a cabo y el posterior post-proceso de los resultados con el objetivo de proporcionar los parámetros necesarios para alimentar el modelo zonal. El modelo propuesto, junto con las correlaciones obtenidas, predicen correctamente el comportamiento del fluido, constituyendo una alternativa interesante para reproducir el proceso de enfriamiento del fluido en los tanques durante largos periodos de tiempo.
Thermal storage devices are widely used in many thermal systems and applications that are characterised by the delay between energy production and consumption, such as thermal solar systems. The improvement in their design and optimisation is a key aspect in the thermal optimisation of the system, where a good preformance of the storage tank can represent a considerable increase in the overall efficiency of the installation. In the subject of optimisation of thermal equipment, Computational Fluid Dynamics have been consolidated as an indispensable tool providing researchers and engineers with a method to test virtually their prototypes with low effort in time, personnel and resources. This thesis is focused in the numerical simulation of unsteady laminar convection in cylindrical domains and its application to the study of the heat transfer and fluid flow that take place in stratified storage tanks.
The first part of this document is devoted to present the methodology followed for the numerical resolution of the governing equation of heat and fluid flow in cylindrical coordinates. The main particularities of the discretisation of the equations in these geometries, as well as the solution procedure for incompressible and transient flow problems are also presented. Special emphasis is given to the verification of the code, the appropriateness of the discretisation adopted and the verification of the numerical solution obtained.
The second part of this thesis is focused on the study of the heat transfer and fluid flow phenomena that take place in stratified storage tanks, including the performance measures and modeling efforts of these devices. The quality of the energy stored is determined by the degree of the thermal stratification of the storage tank, which is affected by several factors such as the mixing due to the inlet streams during load and unload, the heat losses to the environment, among others. In this sense, thermal stratification analysis is carried out by means of the virtual prototyping of the tanks for different working conditions and configurations. In order to measure the performance of the tanks, different parameters are considered. The analysis led to the proposition of a new exergy-based parameter as a tool for assessing and comparing storage tanks. The usefulness of this parameter for quantifying the quality of the energy stored is also shown.
Furthermore, the thermal behaviour of storage tanks during the static mode of operation considering the heat losses to the environment is also analysed. The study is addressed to characterise the cool down of the fluid inside storage tanks for solar thermal systems in the low-to-medium temperature range. The methodology followed, from the identification of the significant non-dimensional parameters that define the problem, the formulation of a zonal prediction model, a parametric numerical study by means of detailed multidimensional CFD computations and the post-processing of the results in order to feed the global model are exposed in detail. Zonal model presented, together with the correlations given are in good agreement with the numerical results and constitute an alternative for the prediction of the long-term performance of the storage tanks during the cooling process.
Wallace, Robert Derring. "Mechanisms Causing Ferric Staining in the Secondary Water System of Brigham City, Utah". BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/903.
Pełny tekst źródłaPedrazzi, Felipe José de Moraes. "Avaliação da qualidade da água do reservatório de Itupararanga, bacia do Alto Sorocaba (SP) /". Rio Claro : [s.n.], 2009. http://hdl.handle.net/11449/92895.
Pełny tekst źródłaAbstract: Considering the great importance of upper Sorocaba basin to the Sorocaba region to water supply, electric generation, irrigation and industrial uses, this work has the main objective to evaluate the water quality of Itupararanga reservoir. The study was conducted with the generation of a georreferenced data base, the water quality evaluation in the spacial gradient (horizontal and vertical distribuition) and temporal (dry and wet climate), trying to know the comportament of some elements and solutions in water column in the reservoir, trying to make the correlation between the data and land use. The results show that in horizontal gradient (upstream - downstream) in the dry period, 90% of collecting points are eutrophic (IET > 54), in the wet period, 60%. In vertical gradient (up - bottom) was observed that the distribuition of some metallic elements and some compounds varied in accordance with pH and chlorophyll-a, indicating that the reservoir eutrophization shifts the algal growing, that causes, with the temperature, stratifies elements in water column. Actions to plan the land use in this watershed are needed to reduce the environment and water quality degradation, making a integrated managing of this important watershed in countryside of São Paulo State.
Orientador: Fabiano Tomazini da Conceição
Coorientador: Washington Barbosa Leite Júnior
Banca: Rodrigo Braga Moruzzi
Banca: Alexandre Marco da Silva
Mestre
Pedrazzi, Felipe José de Moraes [UNESP]. "Avaliação da qualidade da água do reservatório de Itupararanga, bacia do Alto Sorocaba (SP)". Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/92895.
Pełny tekst źródłaCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Considerando a grande importância da bacia do Alto do Rio Sorocaba para a região de Sorocaba, seja para o abastecimento da população, geração de energia elétrica, irrigação e usos industriais, este trabalho teve como objetivo principal avaliar a qualidade da água do reservatório de Itupararanga. O estudo foi desenvolvido pela da geração de um banco de dados georreferenciado, avaliação da qualidade de água no seu gradiente espacial (horizontal e vertical) e temporal (épocas de seca e chuvosa), visando conhecer o comportamento de alguns elementos e compostos na coluna d´água e sua distribuição neste reservatório, correlacionando-os ao uso e ocupação do solo adjacente. Assim, de acordo com os resultados obtidos no gradiente horizontal (montante-jusante) na época de seca 90% dos pontos estavam eutrofizados (IET > 54) e na época de chuva 60%. No gradiente vertical (lâmina d’águafundo) observou-se que a distribuição de elementos metálicos e nutrientes variaram de acordo com o pH e presença de clorofila-a, indicando que a eutrofização do reservatório altera as condições de crescimento de algas que por sua vez afeta a estratificação de elementos na coluna d’agua. Portanto, entende-se que são necessárias ações voltadas ao planejamento do uso e ocupação do solo e gerenciamento integrado desta importante bacia hidrográfica localizada no interior paulista.
Considering the great importance of upper Sorocaba basin to the Sorocaba region to water supply, electric generation, irrigation and industrial uses, this work has the main objective to evaluate the water quality of Itupararanga reservoir. The study was conducted with the generation of a georreferenced data base, the water quality evaluation in the spacial gradient (horizontal and vertical distribuition) and temporal (dry and wet climate), trying to know the comportament of some elements and solutions in water column in the reservoir, trying to make the correlation between the data and land use. The results show that in horizontal gradient (upstream – downstream) in the dry period, 90% of collecting points are eutrophic (IET > 54), in the wet period, 60%. In vertical gradient (up – bottom) was observed that the distribuition of some metallic elements and some compounds varied in accordance with pH and chlorophyll-a, indicating that the reservoir eutrophization shifts the algal growing, that causes, with the temperature, stratifies elements in water column. Actions to plan the land use in this watershed are needed to reduce the environment and water quality degradation, making a integrated managing of this important watershed in countryside of São Paulo State.
Dobbin, Kristin B. "Co-Management and the Fight for Rural Water Justice: Learning from Costa Rican ASADAS". Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/pitzer_theses/33.
Pełny tekst źródłaHaarmann, Tim [Verfasser], Torsten [Akademischer Betreuer] Bickert, Gerold [Akademischer Betreuer] Wefer i Geert-Jan [Akademischer Betreuer] Brummer. "The use of single foraminiferal shells for recording seasonal temperatures and water column stratification and its applicability to the fossil record / Tim Haarmann. Gutachter: Gerold Wefer ; Geert-Jan Brummer. Betreuer: Torsten Bickert". Bremen : Staats- und Universitätsbibliothek Bremen, 2012. http://d-nb.info/1072046679/34.
Pełny tekst źródłaMaxwell, Daniel M. "Water Governance in Bolivia: Policy Options for Pro-Poor Infrastructure Reform". Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/cmc_theses/767.
Pełny tekst źródłaHuhn, Robert. "Beitrag zur thermodynamischen Analyse und Bewertung von Wasserwärmespeichern in Energieumwandlungsketten". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:swb:14-1185976213975-82550.
Pełny tekst źródłaIf hot water storage tanks are optimally integrated in heat or cold supply systems, they contribute to a reduction of required capacity, fuel and operation costs. Unfortunately, even today remarkable heat losses and internal losses occur in hot water storage tanks. The potential for cost and energy reductions is not completely utilized yet. Here, not only heat losses to the ambience, but also internal losses play a decisive role. Main focus of the presented work is the description of the single losses at hot water storage tanks and the determination of the correlation between the losses, the tank design and the mode of operation. Furthermore the effects of the losses in the tank on the efficiency of different types of heat generators and the input of primary energy into the system have been examined. The results are based on extended numerical modeling with the CFD-code Fluent as well as experimental test with three storage tanks. The quantitative comparison of the losses for selected examples shows the current shortcomings but even the potential for an optimized hot water storage tank design
Burin, Rodrigo. "VARIABILIDADE DA QUALIDADE DA ÁGUA E DO ESTADO TRÓFICO DO RESERVATÓRIO DO VACACAÍ MIRIM". Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/7767.
Pełny tekst źródłaThe construction of several reservoirs to meet multiple uses has become essential to human societies. The Vacacaí Mirim s reservoir is used primarily for human supply, accounting for 40% of the Santa Maria water supply. The exam of this reservoir provides a fundamental basis for managing its water quality and its watershed. The objective of this research is to evaluate the variability of the water quality and the trophic status of the Vacacaí Mirim s reservoir. Eight field campaigns were performed between 2010 and 2011, and the water samples were taken at four distributed points along the reservoir and one point located upstream the main tributary river. On the reservoir s sampling points were collected samples from surface (S) and depth (P). The main water quality parameters evaluated were: Water Temperature, pH, Electrical Conductivity, Turbidity, DO, BOD5, COD, TSS, TDS, E. coli, Chlorophyll-a, Ammonium, Nitrite, Nitrate, Total Phosphorus. The trophic status was monitored considering the levels of phosphorus, chlorophyll-a and some biological indicators. The Vacacaí Mirim s reservoir presented a long period of thermal stability, being more or less consistent to the seasonal period, with full circulation only in winter, conferring its classification as warm monomictic. The concentration of most parameters analyzed varied more on a time level than a space level. The parameter that inspires greater concern is the number of E. coli, which in 16% of the time exceeds the limits for class 3 of CONAMA Resolution No. 357/05 making the water unsuitable for this purpose. The correlation analysis also showed strong relationship between some environmental hydrological variables with some parameters of quality. The seasonal variation of the values of the TSI and biological indicators, suggest the Vacacaí Mirim s reservoir as a mesotrophic ecosystem, sometimes tending to eutrophic, so showing an anthropogenic influence. It is suggested to the government, organizations and population, the proper attention to the degradation processes, being necessary the watershed land use control and ordination, the riparian vegetation reestablishment, as well as an adjustment on the effluents emission through appropriate treatment.
A construção de reservatórios visando atender usos múltiplos tornou-se essencial para as sociedades humanas. O reservatório do Vacacaí Mirim é utilizado primordialmente para abastecimento humano, sendo responsável por 40% do fornecimento de água para Santa Maria. O seu estudo proporciona uma base fundamental para o gerenciamento da qualidade de suas águas e de sua bacia hidrográfica. Assim, o objetivo desta pesquisa é avaliar a variabilidade da qualidade da água e do estado trófico do reservatório do Vacacaí Mirim. Foram realizadas oito campanhas de campo entre 2010 e 2011, sendo as coletas de água amostradas em quatro pontos distribuídos ao longo do reservatório e um ponto localizado à montante, no principal rio afluente. Nos pontos do reservatório foram coletadas amostras de superfície (S) e profundidade (P). Em laboratório, as características de qualidade da água foram avaliadas periodicamente, através dos parâmetros: temperatura da água, pH, condutividade elétrica, turbidez, OD, DBO5, DQO, SST, SDT, E. coli, Clorofila-a, Amônia, Nitrito, Nitrato, Fósforo Total e outros Íons. O estado trófico foi avaliado levando em consideração os teores de Fósforo, Clorofila-a e alguns indicadores biológicos. O reservatório do Vacacaí Mirim apresentou um longo período de estabilidade térmica, em maior ou menor grau coerentemente com o período sazonal, apresentando circulação completa somente no inverno, conferindo sua classificação como monomítico quente. As concentrações da maioria dos parâmetros analisados apresentaram maior variação a nível temporal que espacial. O parâmetro que inspira maior preocupação é o número de E. coli, que em 16% do tempo ultrapassa os limites estabelecidos para a classe 3 da Res. CONAMA N°357/05 tornando a água imprópria para este fim. As análises de correlação também mostraram forte relação entre algumas variáveis hidrológicas ambientais com alguns parâmetros de qualidade. A variação sazonal dos valores do IET e indicadores biológicos, sugerem o reservatório do Vacacaí Mirim como um ecossistema mesotrófico, tendendo algumas vezes à eutrofia, já evidenciando influência antropogênica. Sugere-se ao poder público, às organizações e à população, a devida atenção aos processos de degradação, sendo necessário o controle e a ordenação do uso do solo na bacia, o reestabelecimento da vegetação ripariana, bem como uma adequação nos lançamentos de efluentes através de um tratamento adequado.
Rezende, Hugo Cesar. "Estudo teórico e experimental da estratificação térmica : monofásica em tubulações horizontais". [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266765.
Pełny tekst źródłaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-20T11:58:32Z (GMT). No. of bitstreams: 1 Rezende_HugoCesar_D.pdf: 10614958 bytes, checksum: aa2b2ce9d9ec481bd44e74cc217832a2 (MD5) Previous issue date: 2012
Resumo: O escoamento monofásico termicamente estratificado ocorre em tubulações horizontais onde duas camadas diferentes de um mesmo líquido escoam separadamente, sem que ocorra mistura significativa entre as camadas, devido às baixas velocidades e à diferença de densidade (e temperatura). As consequências desse fenômeno não foram consideradas no projeto da maioria das centrais nucleares atualmente em operação. Entretanto, em alguns componentes de centrais nucleares, as diferenças de temperatura podem atingir cerca de 200 °C em uma região bastante estreita nas proximidades da interface entre as camadas de água fria e quente. Nesta condição, as fortes tensões geradas pelas diferenças de dilatação podem comprometer a integridade estrutural e a vida útil de tubulações relacionadas aos sistemas de segurança dessas centrais nucleares. Com o objetivo de estudar o fenômeno da estratificação foi projetada e construída a Instalação de Testes de Estratificação Térmica (ITET), tendo sido realizada uma série de experimentos simulando o bocal de injeção do gerador de vapor de uma central nuclear tipo PWR. Foram estudadas a evolução e as configurações de escoamento em regime de estratificação térmica, assim como a influência do número de Froude nos gradientes de temperatura, na posição da interface entre as camadas de água fria e de água quente e no aparecimento de oscilações desta interface. Os experimentos foram realizados com número de Froude variando de 0,02 a 0,4...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: One phase thermally stratified flows occur when two different layers of the same liquid at different temperatures flow separately in horizontal pipes without appreciable mixing due to the low velocities and difference in density (and temperature). The phenomenon was not considered in the design stage of most of the operating nuclear power plants. However, temperature differences of about 200 °C have been found in a narrow band around the hot and cold water interface in components under stratified flows. Loadings due to this phenomenon affected the integrity of safety related piping systems. The Thermal Stratification Test Facility (ITET), built to allow the experimental simulation of the thermal stratification, is presented so as the results of some experiments simulating one phase thermally stratified flows in geometry and flow condition similar to a nuclear reactor steam generator nozzle. They have the objective of studying the flow configurations and understanding the evolution of the of thermal stratification process. The driving parameter considered to characterize flow under stratified regime due to difference in specific masses is the Froude number. Different Froude numbers, from 0.02 to 0.4, were obtained in different testes by setting injection cold water flow rates and hot water initial temperatures as planned in the test matrix. Results are presented showing the influence of Froude number on the hot and cold water interface position, temperature gradients and striping phenomenon...Note: The complete abstract is available with the full electronic document
Doutorado
Sistemas de Processos Quimicos e Informatica
Doutor em Engenharia Química
MagalhÃes, Frederico Batista. "Qualidade da Ãgua subsuperficial e de fundo no cultivo de tilÃpia em tanques-rede na fazenda campo grande (aÃude Pereira de Miranda, Pentecoste, CearÃ)". Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10416.
Pełny tekst źródłaMankind has an important historical connection with the water especially with Continental Aquatic Ecosystems (CAEs) Worldwide there are about 1386 million km3 of water This value may seem absurdly large almost unimaginable but only a small portion of this amount is freshwater and a smaller portion is still available for consumption by humans This study aimed to determine the effects of tilapia culture in cages held at Fazenda Campo Grande (Weir Pereira de Miranda Pentecost CearÃ) the quality of surface and bottom of the cultivation area and systematically monitor the physical-chemical changes nictimerais changes caused by local weather The study was conducted at Aquaculture Campo Grande located in Weir Public Pereira de Miranda located in Petecoste (Cearà - Brazil) Have chosen two stations (PC - Control Point; PTR - Point in Tanks-Net) Were chosen due to location (50 m away) and divide the similar physical characteristics (depth distance from shore etc ) Meteorological data were obtained from FUNCEME and the the Meteorological Station of Universidade Federal do Cearà The campaigns took place every three weeks and began on 24/03/2012 and were finalized on 07/07/2012 Them were collected waters of sub-surface and bottom in two points and at different times (6 12 18 and 24h00min) Even at the site were measured water temperature pH and oxygen fixation occurred by Winckler method In the laboratory were measured electrical conductivity dissolved oxygen total alkalinity total hardness salinity total ammonia nitrogen nitrite iron II and dissolved phosphorus The water clarity was measured with a Secchi disk Each campaign has generated 324 results in water quality total 1944 results at the end of the work In the end it was concluded that the fish farming Campo Grande eutrophication medium so insignificant that the change in water quality is mainly in the bottom water thermal stratification occurred in fish but there was not always a total mixture of the water body waste dispersion was very low keeping the perimeter of the cages and water quality can be organized as follows in order of increasing water quality (from worse to best water): 1 - bottom water of net cages; 2 - bottom water-point control; 3 - sub-surface water of the control points and net cages
Santos, Guilherme Henrique Sempionato Souza. "Análise numérica de um sistema integrado coletor solar/armazenador térmico /". Bauru : [s.l.], 2007. http://hdl.handle.net/11449/136670.
Pełny tekst źródłaBanca: Vicente Luiz Scalon
Banca: Ricardo Fortes de Miranda
Resumo: Este estudo apresenta uma análise numérica dos campos de temperaturas e velocidades d'água durante seu processo de aquecimento via calor sensível no interior de um armazenador térmico cilíndrico, aquecido lateralmente e adiabático em seu topo e base, visando o estudo da condição de operação de um aquecedor de água coletor solar-armazenador integrados (ICSSWH - Integrated Collector-Storage Water Heater). Em uma segunda análise a influência de um defletor interno é estudada pela definição dos campos de velocidades e temperaturas da água. A abordagem numérica é realizada a partir de um modelo bidimensional, transiente, não linear e em coordenadas cilíndricas, discretizada pela técnica de elementos finitos. A construção do modelo é obtida numericamente através de um código computacional desenvolvido em linguagem de programação C. Os resultados numéricos são validados. Análises transientes dos campos de velocidades e temperaturas bem como das temperaturas de mistura e velocidade de carregamento, com e sem parede interna direcionada (defletor interno) são realizadas com a finalidade de estudar a inlfuência da referida parede na convecção livre nessas condições.
Abstract: This study shows a numerical analysis of the temperature and speed fields of water during the process of heating through sensible heat in the interior of a cylindric thermal storage, heated laterally and with adiabatics top and base, in order to study the operational conditions of an integrated collector-storage solar water heater (ICSSWH). In a second analysis a model with an internal baffle is created and temperature and velocity fields are analysed. The numerical study is done taking into consideration a bidimensional, transient non linear research in cylindric coordenates, discretized by the technique of finite elements. Its solution is obtained numerically through a computational code developed in a C programming language. The numerical results are validated. A transient analysis of the spped and temperature fields so as of the mixing temperatures and the charging speed, with or without the infernal baffle are carried out taking into account the aim of studying the influence of the so called wall in the free convection of those conditions.
Mestre
Huhn, Robert. "Beitrag zur thermodynamischen Analyse und Bewertung von Wasserwärmespeichern in Energieumwandlungsketten". Doctoral thesis, Technische Universität Dresden, 2006. https://tud.qucosa.de/id/qucosa%3A23947.
Pełny tekst źródłaIf hot water storage tanks are optimally integrated in heat or cold supply systems, they contribute to a reduction of required capacity, fuel and operation costs. Unfortunately, even today remarkable heat losses and internal losses occur in hot water storage tanks. The potential for cost and energy reductions is not completely utilized yet. Here, not only heat losses to the ambience, but also internal losses play a decisive role. Main focus of the presented work is the description of the single losses at hot water storage tanks and the determination of the correlation between the losses, the tank design and the mode of operation. Furthermore the effects of the losses in the tank on the efficiency of different types of heat generators and the input of primary energy into the system have been examined. The results are based on extended numerical modeling with the CFD-code Fluent as well as experimental test with three storage tanks. The quantitative comparison of the losses for selected examples shows the current shortcomings but even the potential for an optimized hot water storage tank design.
Santos, Guilherme Henrique Sempionato Souza [UNESP]. "Análise numérica de um sistema integrado coletor solar/armazenador térmico". Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/136670.
Pełny tekst źródłaCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Este estudo apresenta uma análise numérica dos campos de temperaturas e velocidades d'água durante seu processo de aquecimento via calor sensível no interior de um armazenador térmico cilíndrico, aquecido lateralmente e adiabático em seu topo e base, visando o estudo da condição de operação de um aquecedor de água coletor solar-armazenador integrados (ICSSWH - Integrated Collector-Storage Water Heater). Em uma segunda análise a influência de um defletor interno é estudada pela definição dos campos de velocidades e temperaturas da água. A abordagem numérica é realizada a partir de um modelo bidimensional, transiente, não linear e em coordenadas cilíndricas, discretizada pela técnica de elementos finitos. A construção do modelo é obtida numericamente através de um código computacional desenvolvido em linguagem de programação C. Os resultados numéricos são validados. Análises transientes dos campos de velocidades e temperaturas bem como das temperaturas de mistura e velocidade de carregamento, com e sem parede interna direcionada (defletor interno) são realizadas com a finalidade de estudar a inlfuência da referida parede na convecção livre nessas condições.
This study shows a numerical analysis of the temperature and speed fields of water during the process of heating through sensible heat in the interior of a cylindric thermal storage, heated laterally and with adiabatics top and base, in order to study the operational conditions of an integrated collector-storage solar water heater (ICSSWH). In a second analysis a model with an internal baffle is created and temperature and velocity fields are analysed. The numerical study is done taking into consideration a bidimensional, transient non linear research in cylindric coordenates, discretized by the technique of finite elements. Its solution is obtained numerically through a computational code developed in a C programming language. The numerical results are validated. A transient analysis of the spped and temperature fields so as of the mixing temperatures and the charging speed, with or without the infernal baffle are carried out taking into account the aim of studying the influence of the so called wall in the free convection of those conditions.
Umbel, Matthew R. "Prediction of Turbulent Mixing at the Interface of Density Stratified, Shear Flows Using CFD". Ft. Belvoir : Defense Technical Information Center, 1998. http://handle.dtic.mil/100.2/ADA477048.
Pełny tekst źródłaRicci, Giovanni. "Organic matter deposition/resuspension in a one-dimensional physical-biogeochemical model. A modelling study". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10595/.
Pełny tekst źródłaLeaman, Nye Abigail. "Scattering of internal gravity waves". Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/238679.
Pełny tekst źródłaMagalhães, Frederico Batista. "Qualidade da água subsuperficial e de fundo no cultivo de tilápia em tanques-rede na fazenda campo grande (açude Pereira de Miranda, Pentecoste, Ceará)". reponame:Repositório Institucional da UFC, 2013. http://www.repositorio.ufc.br/handle/riufc/18353.
Pełny tekst źródłaSubmitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-15T12:09:42Z No. of bitstreams: 1 2013_dis_fbmagalhães.pdf: 1507818 bytes, checksum: 9692206a8b30849b20decf9e956f08ca (MD5)
Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-15T12:10:05Z (GMT) No. of bitstreams: 1 2013_dis_fbmagalhães.pdf: 1507818 bytes, checksum: 9692206a8b30849b20decf9e956f08ca (MD5)
Made available in DSpace on 2016-07-15T12:10:05Z (GMT). No. of bitstreams: 1 2013_dis_fbmagalhães.pdf: 1507818 bytes, checksum: 9692206a8b30849b20decf9e956f08ca (MD5) Previous issue date: 2013
Mankind has an important historical connection with the water especially with Continental Aquatic Ecosystems (CAEs) Worldwide there are about 1386 million km3 of water This value may seem absurdly large almost unimaginable but only a small portion of this amount is freshwater and a smaller portion is still available for consumption by humans This study aimed to determine the effects of tilapia culture in cages held at Fazenda Campo Grande (Weir Pereira de Miranda Pentecost Ceará) the quality of surface and bottom of the cultivation area and systematically monitor the physical-chemical changes nictimerais changes caused by local weather The study was conducted at Aquaculture Campo Grande located in Weir Public Pereira de Miranda located in Petecoste (Ceará - Brazil) Have chosen two stations (PC - Control Point; PTR - Point in Tanks-Net) Were chosen due to location (50 m away) and divide the similar physical characteristics (depth distance from shore etc ) Meteorological data were obtained from FUNCEME and the the Meteorological Station of Universidade Federal do Ceará The campaigns took place every three weeks and began on 24/03/2012 and were finalized on 07/07/2012 Them were collected waters of sub-surface and bottom in two points and at different times (6 12 18 and 24h00min) Even at the site were measured water temperature pH and oxygen fixation occurred by Winckler method In the laboratory were measured electrical conductivity dissolved oxygen total alkalinity total hardness salinity total ammonia nitrogen nitrite iron II and dissolved phosphorus The water clarity was measured with a Secchi disk Each campaign has generated 324 results in water quality total 1944 results at the end of the work In the end it was concluded that the fish farming Campo Grande eutrophication medium so insignificant that the change in water quality is mainly in the bottom water thermal stratification occurred in fish but there was not always a total mixture of the water body waste dispersion was very low keeping the perimeter of the cages and water quality can be organized as follows in order of increasing water quality (from worse to best water): 1 - bottom water of net cages; 2 - bottom water-point control; 3 - sub-surface water of the control points and net cages
A humanidade tem uma importante ligação histórica com a água em especial com os Ecossistemas Aquáticos Continentais (EACs) No mundo existem cerca de 1 386 milhões de km3 de água sendo apenas 2 5% água doce É de extrema importância o conhecimento das variáveis físico-químicas da água para prever de forma antecipada os fenômenos de estratificação e desestratificação térmica Assim podendo evita perdas financeiras em empreendimentos aquícolas O presente trabalho teve como objetivos determinar quais efeitos a tilapicultura em tanques redes realizada na Fazenda Capo Grande (Pentecoste Ceará) exerce sobre os parâmetros da água subsuperficial e de fundo no cultivo e monitorar sistematicamente as alterações físico-químicas nictimerais causadas pelas alterações meteorológicas locais O trabalho foi realizado na Piscicultura Campo Grande localizada no Açude Publico Pereira de Miranda localizado em Pentecoste (Ceará – Brasil) Foram escolhidos dois pontos de coletas com a mesma profundidade e características semelhantes (PC – Ponto controle localizado a 50 m dos tanques-rede; PTR – Ponto nos Tanques-Rede localizado entre os tanques-rede) Os dados meteorológicos foram obtidos através da FUNCEME e da Estação Meteorológica da UFC As campanhas ocorriam a cada 21 dias se iniciaram no dia 24/03/2012 e foram finalizadas no dia 07/07/2012 Coletava-se águas de sub-superfície (0 30 m) e de fundo (3 90 m) nos dois pontos e em horários diferentes (6 12 18 e 24h00min) Ainda no local foram medidos a temperatura da água pH e ocorria a fixação do oxigênio pelo método de Winckler Em laboratório foram medidos a condutividade elétrica oxigênio dissolvido alcalinidade total dureza total salinidade nitrogênio amoniacal total nitrito ferro II e fósforo dissolvido A transparência da água foi medida com um disco de secchi Cada campanha gerou 324 resultados de qualidade de água totalizando 1944 resultados no fim do trabalho Concluiu-se que a Piscicultura Campo Grande eutrofizou o meio de forma insignificante que a alteração da qualidade de água se deu principalmente na água de fundo ocorreram estratificações térmicas na área da piscicultura mas nem sempre ocorreu à mistura total da massa de água a dispersão de resíduos foi muito baixa mantendo-se no perímetro dos tanques-rede e a qualidade da água pode ser organizada da seguinte forma em ordem crescente de qualidade de água (da pior para a melhor água): 1 – água de fundo dos tanques-rede; 2 – água de fundo do ponto-controle; 3 – água subsuperficial dos pontos controle e tanques-rede
Darras, Marc. "Dilution à la surface de la mer de rejets flottants". Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10005.
Pełny tekst źródłaFey, Jésica Daniela. "Caracterização e modelagem hidrodinâmica da circulação do sistema estuarino do rio Guaratuba (Bertioga - SP) /". São Vicente, 2019. http://hdl.handle.net/11449/181522.
Pełny tekst źródłaResumo: Estuários são ambientes aquáticos de transição entre o continente e o oceano com características únicas, ecológica e economicamente importantes. São condicionados por diversas forçantes naturais e compartilham contribuições terrestres e marinhas. Os principais métodos para estudo hidrodinâmico desses ambientes baseiam-se na análise dos processos de advecção e de mistura das massas de água, gerados pela dinâmica das marés e das descargas dos rios. O presente estudo visa a caracterização hidrodinâmica do estuário do rio Guaratuba (Bertioga, SP) durante as marés de sizígia e de quadratura, a partir de levantamentos hidrográficos realizados com ADCP e CTD e o desenvolvimento de um modelo hidrodinâmico computacional capaz de explicar e simular os processos oceanográficos deste estuário. Os resultados apontaram que, tanto a maré quanto a descarga fluvial têm a capacidade de alterar as vazões e os padrões de salinidade e temperatura no estuário. Em condições de precipitação médias ou na ausência de precipitações, a maré é a forçante dominante do sistema. Durante os períodos de sizígia ocorrem o aumento da turbulência e da mistura vertical. Nas quadraturas, quando as velocidades de corrente são menores, a estratificação vertical é mais estável, e a água salina incursiona até pontos mais internos do estuário. Precipitações na sub-bacia tem relação direta e imediata com o aumento da vazão, afetando a dinâmica e intensificando a estratificação vertical do estuário. O estuário do rio Gua... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Estuaries are transitional aquatic environments, with unique characteristics, ecologically and economically important. They are conditioned by several natural forcings and share land and marine contributions. The main methods to study these environments are based on the analysis of the water masses advection and mixing processes, that are generated by tides and river discharges. The purposes of this study are the hydrodynamic characterization of the Guaratuba’s estuary (Bertioga, SP) during spring and neap tides, based on ADCP and CTD hydrographic surveys, and the development of a computational hydrodynamic model using Delft-3D software, that helps to explain and simulate the main estuarine oceanographic processes. We observed that both, tide and river discharges, have the capacity to alter water flow, as well as salinity and temperature patterns in the estuary. Under mean precipitation conditions or in its absence, tide forces dominate the system. During the spring tide floods, turbulence and vertical mixing increase. During the neap tide floods, when current speed decreases, vertical stratification remains more stable, and saline water penetrates more along the upper estuary. Precipitation episodes in the sub-basin are direct and immediate related to water flow increase, and affect currents dynamics intensifying vertical stratification in the estuary. The Guaratuba estuary is classified as type A, B or D; depending on tidal and river flow conditions. The models we generated... (Complete abstract click electronic access below)
Mestre
Daněk, Tomáš. "Akumulační nádrž tepelného čerpadla". Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230885.
Pełny tekst źródłaFindeisen, Fabian. "Radiale Diffusoren in Warmwasserspeichern: Einfluss des Beladesystems auf Strömungsverhalten und Schichtungsqualität". Technische Universität Chemnitz, 2018. https://monarch.qucosa.de/id/qucosa%3A21083.
Pełny tekst źródłaRadial diffusers have a significant influence on the quality of thermal stratification in hot water storage tanks. In order to improve the efficiency of energy storage, it is necessary to understand the complex flow behaviour. This thesis provides a basis for describing the effects and introduces a CFD simulation model. An innovative storage tank construction is used as the object of investigation, whereby the radial diffuser is mounted directly to a floating ceiling. Advantages of this arrangement are shown, flow effects are described and the influence of different loader geometries on the thermal stratification is investigated. For discharging up to 98 °C at atmospheric pressure, a flow-optimized free-form diffuser was developed to avoid cavitation inside the loading device. The tests also show that a highly asymmetrical and unidirectional flow over the circumference of the radial diffuser can occur during loading. Thanks to countermeasures like baffles and perforated plates, an almost symmetrical outflow can be restored and the stratification quality improved. In addition to numerical studies with RANS and LES, numerous experiments in the laboratory and at a 100m3 store were performed.
Antoine, Stephanie Y. L. Antoine. "The study of cold leg thermal stratification in APEX-CE". Thesis, 2002. http://hdl.handle.net/1957/29718.
Pełny tekst źródłaGraduation date: 2002
Golshan, Azadeh. "Investigation of lake stratification and environmental variables regulating phytoplankton growth in Grahamstown Reservoir". Thesis, 2020. http://hdl.handle.net/1959.13/1414067.
Pełny tekst źródłaPhytoplankton are a natural component of aquatic ecosystems; however, when present in high cell densities as “blooms”, they can pose a significant potential threat to human and ecological health. These phytoplankton blooms are often composed of microorganisms with the potential to produce toxins (cyanobacteria) that can cause adverse health effects in humans and animals through the contamination of waterways used for recreational purposes and as drinking water supplies. There is general agreement that nutrient enrichment of water bodies with nitrogen (N) and phosphorus (P) is the main reason for bloom formation, and that nutrients are typically introduced by inflows to a waterbody. However, sediments can also play an important role in releasing nutrients to water bodies. This can occur by reactivation of sediments under depleted dissolved oxygen levels during thermal stratification. Thus, in order to reduce the nutrient enrichment of aquatic systems, it is important to target both the external and internal nutrient loadings in managing a water reservoir. However, it is also essential to investigate the environmental factors other than nutrients, such as water clarity, water temperature and dissolved oxygen concentration that may influence the formation of algal blooms. This holistic approach has been applied in this study to investigate variations in water quality and the abundance of cyanobacteria in Grahamstown Reservoir, the principal drinking water reservoir of Newcastle and the lower Hunter Region in New South Wales, Australia. Multivariate data analysis methods based on Principal Component Analysis (PCA) and Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) were used in the identification of important water quality variables, as well as the main sources or factors which can influence water quality within Grahamstown Reservoir. PCA and MCR-ALS further were applied to investigate seasonal changes in the abundance and species composition of cyanobacteria in the reservoir in response to changes in environmental factors. Moreover, the seasonal thermal stratification pattern and its role in the formation of algal blooms was also investigated in Grahamstown Reservoir. A part of this study was also focused on an overview of the issues relating to taste and odour problems in Grahamstown Reservoir. This part of the project was aimed at assessing the occurrence of cyanobacteria abundance to better understand their relative potential to produce significant tastes and odours which affect water quality. The water quality data examined in this study has been collected from different sites within Grahamstown Reservoir by routine sampling by Hunter Water Corporation (HWC) who manage the drinking water storage. The expected outcome of this study is the identification of the factors and sources of contaminants which could influence the water quality of Grahamstown Reservoir and thereby further inform the management strategies needed to prevent and minimise the risk of algal blooms in the future. Also, determination of the environmental factors other than nutrients that may influence the formation of algal blooms.
Golshan, Azadeh. "Investigation of lake stratification and environmental variables regulating phytoplankton growth in Grahamstown Reservoir". Thesis, 2020. http://hdl.handle.net/1959.13/1414066.
Pełny tekst źródłaPhytoplankton are a natural component of aquatic ecosystems; however, when present in high cell densities as “blooms”, they can pose a significant potential threat to human and ecological health. These phytoplankton blooms are often composed of microorganisms with the potential to produce toxins (cyanobacteria) that can cause adverse health effects in humans and animals through the contamination of waterways used for recreational purposes and as drinking water supplies. There is general agreement that nutrient enrichment of water bodies with nitrogen (N) and phosphorus (P) is the main reason for bloom formation, and that nutrients are typically introduced by inflows to a waterbody. However, sediments can also play an important role in releasing nutrients to water bodies. This can occur by reactivation of sediments under depleted dissolved oxygen levels during thermal stratification. Thus, in order to reduce the nutrient enrichment of aquatic systems, it is important to target both the external and internal nutrient loadings in managing a water reservoir. However, it is also essential to investigate the environmental factors other than nutrients, such as water clarity, water temperature and dissolved oxygen concentration that may influence the formation of algal blooms. This holistic approach has been applied in this study to investigate variations in water quality and the abundance of cyanobacteria in Grahamstown Reservoir, the principal drinking water reservoir of Newcastle and the lower Hunter Region in New South Wales, Australia. Multivariate data analysis methods based on Principal Component Analysis (PCA) and Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) were used in the identification of important water quality variables, as well as the main sources or factors which can influence water quality within Grahamstown Reservoir. PCA and MCR-ALS further were applied to investigate seasonal changes in the abundance and species composition of cyanobacteria in the reservoir in response to changes in environmental factors. Moreover, the seasonal thermal stratification pattern and its role in the formation of algal blooms was also investigated in Grahamstown Reservoir. A part of this study was also focused on an overview of the issues relating to taste and odour problems in Grahamstown Reservoir. This part of the project was aimed at assessing the occurrence of cyanobacteria abundance to better understand their relative potential to produce significant tastes and odours which affect water quality. The water quality data examined in this study has been collected from different sites within Grahamstown Reservoir by routine sampling by Hunter Water Corporation (HWC) who manage the drinking water storage. The expected outcome of this study is the identification of the factors and sources of contaminants which could influence the water quality of Grahamstown Reservoir and thereby further inform the management strategies needed to prevent and minimise the risk of algal blooms in the future. Also, determination of the environmental factors other than nutrients that may influence the formation of algal blooms.
Alsagheer, Fozi. "An Investigation of Methods to Enhance Stratification in Solar Domestic Hot Water Tanks". 2011. http://hdl.handle.net/10222/13332.
Pełny tekst źródłaFontes, Cláudia Lindim. "Modelling of water quality in the Alqueva Reservoir, Portugal". Doctoral thesis, 2011. http://hdl.handle.net/1822/12496.
Pełny tekst źródłaEutrophication is a serious environmental problem in lakes and reservoirs worldwide. The eutrophic Alqueva reservoir (Portugal) is the largest western European reservoir and constitutes a vital regional water resource. The river Guadiana, which is the main tributary to the Alqueva reservoir, imports large nutrient loads leading to eutrophication being an issue in this waterbody. But despite its importance and problems, few scientific studies concerning the Alqueva exist. This work aims at contributing to foster the understanding of water ecology in the Alqueva reservoir through the use of data analysis techniques and numerical modelling. The results contained herein can be used to assist management decisions in this waterbody and the modelling effort can be used to obtain forecasts in this and other reservoirs and improve understanding of ecological behavior there. Data analysis methods, namely time series analysis, were applied to monitoring data collected between 2003-2009 at several locations and depths in the Alqueva reservoir in order to infer possible spatial and temporal patterns. The monitoring data comprised climatology, hydrology and water quality data from different sources. Data analysis showed that the Alqueva behavior presents high interannual variability. This is mainly a consequence of the high variability of precipitation, nutrient loads and Guadiana hydrological regimen. It was found that the system is P-limited and that nutrients input is mostly dependent on the main tributary input loads. Therefore management schemes aimed at improving the trophic level in the Alqueva should focus on reducing phosphorus in the Guadiana inflow. Numerical modelling main goals were to develop and apply tools to simulate the main ecological traits in the Alqueva reservoir. A new numerical model to simulate eutrophication processes in lakes and reservoirs based on a hybrid deterministic-stochastic approach was developed. A plain methodology to estimate nutrient loads in a basin was also developed. These tools were used together with the finite element based hydrodynamic model RMA-10 to perform simulations of currents, thermal structure and eutrophication in the Alqueva reservoir. The models were successfully calibrated and validated in both two-dimensional and three-dimensional versions. Model performance was assessed by comparing simulation results with in situ measured data. It was found that the models reproduced Alqueva thermal structure quite accurately and eutrophication related trends reasonably well. The performance of the eutrophication tool was constrained by the availability and quality of input and forcing data. It was shown that the particular geomorphological and hydrological characteristics of the reservoir together with local climate features are responsible for the existence of two distinct ecological regions within the reservoir whose boundary can be placed at a transect south of monitoring station 3: - The upper part of the reservoir is a shallow channel like region with riverine characteristics that is interrupted by a few scattered deeper pools. This area receives the major nutrients input and is eutrophic. Hydrodynamic in this area is governed by hydraulically induced currents from the Guadiana. - The lower part of the reservoir is a deep lacustrine area that presents stable thermal and oxygen stratification in summer (April – October). In this region, wind induced currents and thermal stratification are the dominant hydrodynamic traits. Wind is dominant over hydraulic flow during all year and affects mostly the surface circulation. Model results indicate that the velocities in the reservoir are always smaller than 0.25 m/s, with the higher values occurring in the upper reservoir area. The Alqueva was found to present a monomictic behavior with a seasonal summer stratification that is responsible for generating anoxic bottom waters during dry season. An autumnal overturn leads to a fully mixed water column in winter season. Model findings, corroborated by data, indicate that phytoplankton in the Alqueva peaks in spring and in autumn with productivity in the upper reservoir area presenting values much higher than in the lower part. Dry season ecology seems to be ruled by stratification while wet season ecology main driving force appears to be the nutrients load through the main tributary. The Alqueva was build to boost economic development in the region and provide irrigation water for agriculture activities. It can be inferred from the results of the present work that the major problem it may face is the impacts of the poor water quality coming from the Guadiana. The Guadiana river carries wastewater with a high level of nutrients from a large Spanish population, from industries and from agriculture activities. The development of effective water quality management in this reservoir should therefore focus on nutrient containment strategies for the Guadiana river inflow.
A eutrofização constitui um sério problema ambiental em lagos e albufeiras. A albufeira de Alqueva (Portugal) é a maior albufeira da Europa ocidental e constitui um importante recurso aquático regional. O principal afluente de Alqueva, o rio Guadiana, introduz elevadas cargas de nutrientes na albufeira fazendo com que a eutrofização seja motivo de preocupação nesta albufeira. Apesar da sua importância e problemas, existem poucos estudos científicos sobre a albufeira de Alqueva. Este trabalho tem como objectivo contribuir para o conhecimento e compreensão da ecologia aquática na albufeira de Alqueva através do uso de análise de dados e modelação matemática. Os resultados obtidos podem ser utilizados na tomada de decisões de gestão nesta albufeira e o trabalho de modelação pode ser utilizado para efectuar previsões nesta ou noutras albufeiras ou lagos. Foram aplicados métodos de análise de dados, nomeadamente métodos de análise de séries temporais, a dados de campanhas de monitorização recolhidos no período 2003-2009 em diferentes pontos da albufeira de Alqueva para inferir da existência de padrões espaciais e temporais. Os dados de monitorização são oriundos de diferentes fontes e abrangem climatologia, hidrologia e qualidade da água A análise de dados permitiu concluir que a ecologia do Alqueva tem uma elevada variabilidade interanual que é consequência da elevada variabilidade da precipitação, cargas de nutrientes e regime hidrológico. Concluiu-se que o nutriente limitante é o fósforo e que a entrada de nutrientes no sistema depende sobretudo das cargas que entram pelo afluente principal. Donde resulta que uma gestão eficiente da melhoria do estado trófico da albufeira deve centrar-se na redução do fósforo nas afluências do Guadiana. Os principais objectivos da modelação foram desenvolver e aplicar ferramentas para simular as principais características ecológicas da albufeira de Alqueva. Desenvolveu-se um novo modelo matemático para simular a eutrofização em lagos e albufeiras baseado numa abordagem híbrida determinística-estocástica. Desenvolveu-se também uma metodologia simples para estimar cargas de nutrientes em bacias hidrográficas. Estes instrumentos foram utilizados em conjunto com o modelo hidrodinâmico RMA10, baseado no método dos elementos finitos, para simular correntes, estrutura térmica e eutrofização na albufeira de Alqueva. Os modelos foram calibrados e validados com sucesso nas versões tridimensional e bidimensional integrada lateralmente. O desempenho dos modelos foi avaliado por comparação entre os resultados de simulações e medidas experimentais realizadas in situ. Verificou-se que os modelos reproduzem com grande exactidão a estrutura térmica da albugeira de Alqueva e razoavelmente bem as variações relacionadas com a eutrofização. O desempenho do modelo de eutrofização foi condicionado pela disponibilidade e qualidade dos dados de entrada e de forçamento. Mostrou-se que as características geomorfológicas e hidrológicas particulares da albufeira, em conjunto com características climáticas locais, são responsáveis pela existência de duas zonas ecológicas distintas na albufeira, cuja fronteira se localiza a sul da estação de amostragem 3: - A parte superior da albufeira é uma região de leito linear com águas pouco profundas, interrompida a espaços por lagoas mais profundas, que tem características fluviais. Esta zona é muito eutrófica e por ela entram a maior parte dos nutrientes do sistema. A hidrodinâmica nesta área é governada por correntes induzidas pelo fluxo do Guadiana. - A parte inferior da albufeira é uma região lacustre profunda que apresenta estratificações térmica e de oxigénio estáveis durante o verão (Abril - Outubro). Nesta zona as características hidrodinâmicas dominantes são as correntes induzidas pelo vento e a estratificação térmica. O vento é dominante sobre o fluxo hidráulico durante todo o ano e afecta sobretudo a circulação à superfície. Os resultados da modelação indicam que as velocidades na albufeira são sempre inferiores a 0.25 m/s, com os maiores valores a ocorrer na parte superior da albufeira. Concluiu-se que a albufeira de Alqueva apresenta um comportamento monomíctico com uma estratificação sazonal de verão que é responsável pela geração de camadas de água anóxica no fundo da albufeira durante a estação seca. A circulação convectiva outonal dá origem a uma coluna de água completamente misturada na estação do inverno. Os resultados de modelação, corroborados por dados de campo, indicam que o fitoplâncton no Alqueva apresenta picos primaveris e outonais, com a produtividade na parte superior da albufeira a apresentar sempre valores muito superiores à da parte inferior. A ecologia da estação seca parece ser governada pela estratificação ao passo que a força motriz da ecologia da estação húmida aparenta ser a carga de nutrientes que entra através do afluente principal. A barragem de Alqueva foi construída para fomentar o desenvolvimento económico regional e fornecer água de irrigação para actividades agrícolas. Dos resultados obtidos neste trabalho pode-se concluir que o maior problema com que a albufeira se depara é os impactos da água de baixa qualidade que é trazida pelo rio Guadiana. O Guadiana transporta efluentes com um elevado nível de nutrientes provenientes de uma vasta população espanhola, de indústrias e de actividades agrícolas. Consequentemente, o desenvolvimento de uma gestão de qualidade da água eficaz nesta albufeira deve centrar-se em estratégias de remediação/contenção do fósforo trazido pelo Guadiana.
"Water Quality and Thermal Stratification of Cragin Reservoir: Current and Future Impact of Forest Fires". Master's thesis, 2018. http://hdl.handle.net/2286/R.I.51741.
Pełny tekst źródłaDissertation/Thesis
Masters Thesis Civil, Environmental and Sustainable Engineering 2018
Tsai, Wan-Jung, i 蔡宛蓉. "Reconstruction of surface water stratification changes in the northwestern Pacific of the last 180 kyrs". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/91026449447758481639.
Pełny tekst źródła國立中山大學
海洋科學系研究所
104
The North Pacific Intermediate Water (NPIW) plays an important role on driving the global climate change, which can control the heat transportation from low to high latitude. However, the long-term changes of NPIW are still rare understood. In this study, by using Unsaturated Alkenone Index (U_37^(k^'' )) and foraminiferal Mg/Ca to represent the different temperature of water depths, the historical hydrography evolution of water profile can be reconstructed. Therefore, we can investigate the relationship between climate events and the circulation changes in northwestern Pacific.As the result, using ΔT to reconstruct the mixed layer change is applicable in Shatsky Rise, and we suggest to use other species which have small estimating errors, in order to get more reliability results on western Pacific paleoceanographic studies. The U_37^(k^'' ) temperatures reveal a regional cold period during MIS 5e in Shatsky Rise, which is probably not caused by the movement of Subarctic Front, but the violently fluctuation of the Kuroshio Extension. The result ofΔTU-N and ΔTU-G show thatΔTU-G are more sensitive than ΔTU-N, in which that ΔTU-N is more truly represent the change of NPIW. Reconstructed ΔTU-N and ΔTU-G curves indicate that MIS 2 is warmer than MIS6. Otherwise, ventilation age data confirmed that the mixed layer is deeper during the late MIS 3. In MIS 5, both ΔTU-N and ΔTU-G records illustrate the increased mixed layer depth during warm periods, but decreased in cold periods. Therefore, the stratification is weakened which the circulation of NPIW can be strengthen during the cold periods.
Marshall, Natalie School of Biological Earth & Environmental Sciences UNSW. "Geomorphic controls on thermal stratification in the floodplain lakes of the Macdonald River, New South Wales". 2007. http://handle.unsw.edu.au/1959.4/40581.
Pełny tekst źródła