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1
Godin, André. "The calibration of shallow water multibeam echo-sounding systems". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23800.pdf.
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2
Ding, Xiaoliang. "Numberical solution of the shallow-water equations on distributed memory systems". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0006/MQ40742.pdf.
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3
Akponasa, Gladys Aruore. "Solution of the contravariant shallow water equations using boundary-fitted coordinate systems". Thesis, University of Oxford, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314835.
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4
Winter, Thomas A. "Examination of time-reversal acoustic application to shallow water active sonar systems". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2000. http://handle.dtic.mil/100.2/ADA378874.
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5
Dudzinski, Michael [Verfasser]. "Well-Balanced Bicharacteristic-Based Finite Volume Schemes for Multilayer Shallow Water Systems / Michael Dudzinski". München : Verlag Dr. Hut, 2014. http://d-nb.info/106456058X/34.
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6
Kneis, David. "A water quality model for shallow river lake systems and its application in river basin management". Phd thesis, [S.l.] : [s.n.], 2007. http://opus.kobv.de/ubp/volltexte/2007/1464.
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7
Amour, Frédéric. "3-D modeling of shallow-water carbonate systems : a scale-dependent approach based on quantitative outcrop studies". Phd thesis, Universität Potsdam, 2013. http://opus.kobv.de/ubp/volltexte/2013/6662/.
Testo completoAbstract (sommario):
The study of outcrop modeling is located at the interface between two fields of expertise, Sedimentology and Computing Geoscience, which respectively investigates and simulates geological heterogeneity observed in the sedimentary record. During the last past years, modeling tools and techniques were constantly improved. In parallel, the study of Phanerozoic carbonate deposits emphasized the common occurrence of a random facies distribution along single depositional domain. Although both fields of expertise are intrinsically linked during outcrop simulation, their respective advances have not been combined in literature to enhance carbonate modeling studies. The present study re-examines the modeling strategy adapted to the simulation of shallow-water carbonate systems, based on a close relationship between field sedimentology and modeling capabilities.
In the present study, the evaluation of three commonly used algorithms Truncated Gaussian Simulation (TGSim), Sequential Indicator Simulation (SISim), and Indicator Kriging (IK), were performed for the first time using visual and quantitative comparisons on an ideally suited carbonate outcrop. The results show that the heterogeneity of carbonate rocks cannot be fully simulated using one single algorithm. The operating mode of each algorithm involves capabilities as well as drawbacks that are not capable to match all field observations carried out across the modeling area.
Two end members in the spectrum of carbonate depositional settings, a low-angle Jurassic ramp (High Atlas, Morocco) and a Triassic isolated platform (Dolomites, Italy), were investigated to obtain a complete overview of the geological heterogeneity in shallow-water carbonate systems. Field sedimentology and statistical analysis performed on the type, morphology, distribution, and association of carbonate bodies and combined with palaeodepositional reconstructions, emphasize similar results. At the basin scale (x 1 km), facies association, composed of facies recording similar depositional conditions, displays linear and ordered transitions between depositional domains. Contrarily, at the bedding scale (x 0.1 km), individual lithofacies type shows a mosaic-like distribution consisting of an arrangement of spatially independent lithofacies bodies along the depositional profile. The increase of spatial disorder from the basin to bedding scale results from the influence of autocyclic factors on the transport and deposition of carbonate sediments.
Scale-dependent types of carbonate heterogeneity are linked with the evaluation of algorithms in order to establish a modeling strategy that considers both the sedimentary characteristics of the outcrop and the modeling capabilities. A surface-based modeling approach was used to model depositional sequences. Facies associations were populated using TGSim to preserve ordered trends between depositional domains. At the lithofacies scale, a fully stochastic approach with SISim was applied to simulate a mosaic-like lithofacies distribution. This new workflow is designed to improve the simulation of carbonate rocks, based on the modeling of each scale of heterogeneity individually.
Contrarily to simulation methods applied in literature, the present study considers that the use of one single simulation technique is unlikely to correctly model the natural patterns and variability of carbonate rocks. The implementation of different techniques customized for each level of the stratigraphic hierarchy provides the essential computing flexibility to model carbonate systems. Closer feedback between advances carried out in the field of Sedimentology and Computing Geoscience should be promoted during future outcrop simulations for the enhancement of 3-D geological models.Das Modellieren von geologischen Aufschlüssen liegt der Schnittstelle zwischen zwei geo-logischen Teildisziplinen, der Sedimentologie und der geologischen Modellierung. Hierbei werden geologische Heterogenitäten untersucht und simuliert, welche im Aufschluss beobachtet wurden. Während der letzten Jahre haben sich die Werkzeuge und die Technik der Modellierung stetig weiter-entwickelt. Parallel dazu hat die Untersuchung der phanerozoischen Karbonatablagerungen ihren Fokus auf gemeinsamen Vorkommen von zufälligen Faziesverteilungen in beiden Ablagerungs-gebieten. Obwohl beide Teildisziplinen durch die Aufschlussmodellierung eigentlich verbunden sind, wurden ihre jeweiligen Vorteile in der Literatur nicht miteinander verbunden, um so eine Verbesserung ähnlicher Studien zu erreichen. Die vorliegende Studie überprüft erneut die Modellierungsstrategie, angepasst an die Simulation von Flachwasser-Karbonat-Systemen und basierend auf einer engen Beziehung zwischen Sedimentologie und Modellierung. Die vorliegende Arbeit behandelt erstmals die Evaluierung der drei am häufigsten verwendeten Algorithmen „Truncated Gaussian Simulation (TGSim)“, „Sequential Indicator Simulation (SISim)“ und „Indicator Kriging (IK)“, um sie visuell und quantitativ mit dem entsprechenden Aufschluss zu vergleichen. Die Ergebnisse zeigen, dass die Heterogenität von Karbonatgesteinen nicht komplett mit nur einem Algorithmus simuliert werden kann. Die Eigenschaften jedes einzelnen Algorithmus beinhalten Vor- und Nachteile, sodass kein Algorithmus alle Beobachtungen aus dem Aufschluss widerspiegelt. Die zwei Endglieder im Spektrum der Ablagerungsbedingungen von Karbonaten, eine flachwinklige, jurassische Karbonat-Rampe (Hoher Atlas, Marokko) und eine isolierte, triassische Plattform (Dolomiten, Italien), wurden untersucht, um einen kompletten Überblick über die verschiedenen Heterogenitäten in Flachwasser-Karbonat- Systemen zu erhalten. Sedimentologische und statistische Analysen wurden für die verschiedenen Typen, Morphologien, Verteilungen und Assoziationen von Karbonatablagerungen durchgeführt und mit paläogeografischen Rekonstruktionen kombiniert und zeigen ähnliche Ergebnisse. Im Beckenmaßstab zeigen die Faziesassoziationen, bestehend aus Fazieszonen mit ähnlichen Ablagerungsbedingungen, einen linearen und kontinuierlichen Übergang zwischen den einzelnen Ablagerungsbereichen. Im Gegensatz dazu zeigt für einzelne Lithofaziestypen im Maßstab einzelner Schichten eine mosaikartige Verteilung, bestehend aus einer Anordnung räumlich unabhängiger Lithofazieszonen entlang des Ablagerungsprofils. Das Ansteigen der räumlichen Unordnung von der beckenweiten Ablagerung zur Ablagerung einzelner Schichten resultiert aus dem Einfluss autozyklischer Faktoren bei der Ablagerung von Karbonaten. Die Skalenabhängigkeit von Karbonat-Heterogenität ist mit der Auswertung der Algorithmen verknüpft um eine Modellierungsstrategie zu etablieren, welche sowohl die sedimentären Charakteristiken des Aufschlusses als auch die Modellierfähigkeit berücksichtigt. Für die Modellierung der Ablagerungssequenzen wurde ein flächenbasierter Ansatz verwendet. Die Faziesassoziationen wurden durch die Benutzung des TGSim-Algorithmus simuliert, um die regulären Trends zwischen den einzelnen Ablagerungsgebieten zu erhalten. Im Bereich der verschiedenen Lithofazien wurde mit dem SISim-Algorithmus, ein voll stochastischer Ansatz angewendet, um die mosaikartige Verteilung der Lithofazies-Typen zu simulieren. Dieser neue Arbeitsablauf wurde konzipiert, um die Simulierung von Karbonaten auf Basis der einzelnen Heterogenitäten in verschiedenen Größenordnungen zu verbessern. Im Gegensatz zu den in der Literatur angewendeten Simulationsmethoden berücksichtigt diese Studie, dass eine einzelne Modellierungstechnik die natürlichen Ablagerungsmuster und Variabilität von Karbonaten wahrscheinlich nicht korrekt abbildet. Die Einführung verschiedener Techniken, angepasst auf die verschiedenen Ebenen der stratigrafischen Hierarchie, liefert die notwendige Flexibilität um Karbonatsysteme korrekt zu modellieren. Eine enge Verknüpfung zwischen den Fortschritten auf dem Gebieten der Sedimentologie und dem Gebiet der modellierenden Geowissenschaften sollte weiterhin bestehen, um auch zukünftig bei der Simulation von geologischen Gelände-Aufschlüssen eine Verbesserung der 3-D-Modellierung zu erreichen.
8
Pearson, Richard Vincent. "Simulation of shallow water hydrodynamics and species transport using elliptically generated non-orthogonal boundary-fitted coordinate systems". Thesis, University of Salford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308220.
Testo completo
9
Karabulut, Dogan Ozge. "Monitoring Of Water Clarity, And Submerged And Emergent Plant Coverages In Shallow Lake Wetlands Using Remote Sensing Techniques". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608235/index.pdf.
Testo completoAbstract (sommario):
Shallow lake wetlands, for which aquatic plants (macrophytes) and water clarity are the key indicators of ecological status, provide valuable services to wildlife and humanity. Conservation of these ecosystems requires development of rapid and large scale monitoring strategies, where remote sensing and Geographic Information Systems (GIS) can be advantageous.
In this study, high spatial resolution Quickbird and IKONOS and medium spatial resolution Landsat and Aster images were used for monitoring the aquatic plants and water clarity in Lakes Mogan and Eymir.
Classification of emergent plants with high spatial resolution data yielded overall accuracies greater than 90% for both lakes, while overall accuracies obtained from the medium spatial resolution data ranged between 80% and 93% for Lake Mogan and between 70% and 78% for Lake Eymir. It was found that there was 23ha reed bed loss in Lake Mogan between 2002 and 2005 and an additional 14ha was lost between 2005 and 2006. In Lake Eymir, no significant change in reed bed area was detected from high spatial resolution imageshowever medium spatial resolution images revealed 8ha of change which was attributed to the presence of mixed pixels due to low resolution. The overall accuracies for submerged plant coverage classification from Quickbird images in Lake Mogan were 83% (2005) and 79% (2006) and for classification of submerged plants species were 72% (2005) and 69% (2006). Moreover, it was found that blue band together with the ratio of red band to blue band, were the best predictors of Secchi disc depth.
10
Brettle, Matthew John. "Sedimentology and high-resolution sequence stratigraphy of shallow water delta systems in the early Marsdenian (Namurian) Pennine Basin, Northern England". Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367677.
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Leduc, Meagan. "Seasonal Water Column Dynamics Exert Strong Control On The Chemical Partitioning Of Benthic Phosphorus Pools Of Shallow Eutrophic Freshwater Systems". ScholarWorks @ UVM, 2020. https://scholarworks.uvm.edu/graddis/1183.
Testo completoAbstract (sommario):
In shallow lake systems, phosphorus (P) availability to cyanobacteria populations is often controlled by the release (internal loading) or sequestration of sediment P. This study provides novel insight into the feedbacks between the water column and benthic P pools across multiple time scales and explain how these dynamics influence chemical partitioning of P in lake sediment. Phosphorus partitioning in seasonal sediment core time series collected from a shallow eutrophic bay of Lake Champlain were quantified with SEDEX and enzyme hydrolysis selective extraction schemes. Time series extraction data were interpreted with concurrent water column physical and biogeochemical monitoring data to examine the relationship between water column dynamics and P partitioning of near-surface sediments in this intensively monitored system. Nonmetric multidimensional scaling analysis (NMDS) indicates that both sediment and water column time series cluster seasonally, linking water column variables such as pH, thermal stratification, and dissolved oxygen concentrations to the behavior of sediment P pools over the course of a year. Iron (FeP), exchangeable (Ex-P), calcium carbonate bound P (Ca-P) pools, and enzyme labile P were highly dynamic, especially in spring and summer. The SEDEX concentration data indicated that the sediment was mainly composed of inorganic bound P (De-P), but FeP and Ex-P pools proportionally varied most between sampling dates. Remarkably, while highly dynamic on an intra-annual timescale, the sediment ultimately returned to similar P concentration and chemical partitioning by late fall. The hysteretic nature of this interaction between water column dynamics and sediment P inventory/partitioning was clearly driven by systematic seasonal changes in water column physical, chemical, and ecological conditions governed by northern Vermont’s climate and the physical configuration of the bay and its watershed. This study provides novel insight into the unique challenges associated with improving water quality in lake systems impacted by internal loading of legacy P.
12
Zhang, Fan. "A NEW PARADIGM OF MODELING WATERSHED WATER QUALITY". Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2387.
Testo completoAbstract (sommario):
Accurate models to reliably predict sediment and chemical transport in watershed water systems enhance the ability of environmental scientists, engineers and decision makers to analyze the impact of contamination problems and to evaluate the efficacy of alternative remediation techniques and management strategies prior to incurring expense in the field. This dissertation presents the conceptual and mathematical development of a general numerical model simulating (1) sediment and reactive chemical transport in river/stream networks of watershed systems; (2) sediment and reactive chemical transport in overland shallow water of watershed systems; and (3) reactive chemical transport in three-dimensional subsurface systems. Through the decomposition of the system of species transport equations via Gauss-Jordan column reduction of the reaction network, fast reactions and slow reactions are decoupled, which enables robust numerical integrations. Species reactive transport equations are transformed into two sets: nonlinear algebraic equations representing equilibrium reactions and transport equations of kinetic-variables in terms of kinetically controlled reaction rates. As a result, the model uses kinetic-variables instead of biogeochemical species as primary dependent variables, which reduces the number of transport equations and simplifies reaction terms in these equations. For each time step, we first solve the advective-dispersive transport of kinetic-variables. We then solve the reactive chemical system node by node to yield concentrations of all species. In order to obtain accurate, efficient and robust computations, five numerical options are provided to solve the advective-dispersive transport equations; and three coupling strategies are given to deal with the reactive chemistry. Verification examples are compared with analytical solutions to demonstrate the numerical accuracy of the code and to emphasize the need of implementing various numerical options and coupling strategies to deal with different types of problems for different application circumstances. Validation examples are presented to evaluate the ability of the model to replicate behavior observed in real systems. Hypothetical examples with complex reaction networks are employed to demonstrate the design capability of the model to handle field-scale problems involving both kinetic and equilibrium reactions. The deficiency of current practices in the water quality modeling is discussed and potential improvements over current practices using this model are addressed.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering
13
Delano, Kristen Adams. "Metapopulation Dynamics, Habitat Quality, and Spatial Scale: Variation in Reproductive Output of the Baltic Clam, Macoma balthica, in Shallow Systems of the Chesapeake Bay". W&M ScholarWorks, 2004. https://scholarworks.wm.edu/etd/1539617825.
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Ay, Ahmet. "An Experimental Study Of Silicate-polymer Gel Systems To Seal Shallow Water Flow And Lost Circulation Zones In Top Hole Drilling". Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614813/index.pdf.
Testo completoAbstract (sommario):
Shallow water flow and lost circulation are frequently encountered problems during drilling top holes of oil, gas or geothermal wells. Plenty of methods have been applied to overcome these problems. Placement of silicate based gel systems is one of the oldest methods to seal such undesired zones.
For this study, sodium-silicate based gel system is investigated experimentally. This gel system is deliberately delayed multi-component system mixed as a uniform liquid at the surface but desired to form strong gel where it is placed in the well. The experimentally analyzed system is composed of distilled water, sodium-silicate solution, polymer solution, lost circulation materials, weighting agent and organic initiator. In this study, effect of these components on gel time, gel quality and gel strength at room temperature is investigated as a function of their concentration.
To be able to compare gelation time of different compositions, gel time tests were performed by following the developed method in this study. Observation codes were defined to be able to compare the gel qualities of different compositions. For gel time and quality tests, sodium-silicate concentrations from 3.5% to 15% were studied and the concentrations between 7.5% and 10% were found as optimum. Gel time is getting higher as silicate-initiator ratio (SIR) increases for these optimum concentrations. It was also determined that, addition of polymers reduces the gel time and increases the elasticity of the resulting gels.
Long term gelation process was investigated by monitoring turbidity (NTU) of the mixtures and plotting NTU versus time curves. Viscosity development curves obtained from rotational viscometer at various constant shear rates indicated reduced gelation times with increasing shear rate. Furthermore, by using modified High-Pressure, High-Temperature filter press cell, it was determined that, addition of lost circulation materials increases the extrusion pressure.
15
Sollich, Miriam [Verfasser], Solveig [Akademischer Betreuer] Bühring, Solveig [Gutachter] Bühring e Eoghan [Gutachter] Reeves. "Exploring the lipidomes of shallow-water and deep-sea hydrothermal systems / Miriam Sollich ; Gutachter: Solveig Bühring, Eoghan Reeves ; Betreuer: Solveig Bühring". Bremen : Staats- und Universitätsbibliothek Bremen, 2018. http://d-nb.info/1170321070/34.
Testo completo
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Amour, Frédéric [Verfasser], e Maria [Akademischer Betreuer] Mutti. "3-D modeling of shallow-water carbonate systems : a scale-dependent approach based on quantitative outcrop studies / Frédéric Amour. Betreuer: Maria Mutti". Potsdam : Universitätsbibliothek der Universität Potsdam, 2013. http://d-nb.info/1037027515/34.
Testo completo
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Nar, Fatih. "Vessel Segmentation Using Shallow Water Equations". Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613197/index.pdf.
Testo completoAbstract (sommario):
This thesis investigates the feasibility of using fluid flow as a deformable model for
segmenting vessels in 2D and 3D medical images. Exploiting fluid flow in vessel
segmentation is biologically plausible since vessels naturally provide the medium for
blood transportation. Fluid flow can be used as a basis for powerful vessel
segmentation because streaming fluid regions can merge and split providing
topological adaptivity. In addition, the fluid can also flow through small gaps formed
by imaging artifacts building connections between disconnected areas. In our study,
due to their simplicity, parallelism, and low computational cost compared to other
fluid simulation methods, linearized shallow water equations (LSWE) are used. The
method developed herein is validated using synthetic data sets, two clinical datasets,
and publicly available simulated datasets which contain Magnetic Resonance
Angiography (MRA) images, Magnetic Resonance Venography (MRV) images and
retinal angiography images. Depending on image size, one to two order of magnitude
speed ups are obtained with developed parallel implementation using Nvidia
Compute Unified Device Architecture (CUDA) compared to single-core and multicore
CPU implementation.
18
Michaelis, Bjoern. "Dissolved oxygen dynamics in a shallow stream system /". View online ; access limited to URI, 2005. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3186915.
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Chiapolino, Alexandre. "Quelques contributions à la modélisation et simulation numérique des écoulements diphasiques compressibles". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0757/document.
Testo completoAbstract (sommario):
Ce manuscrit porte sur la modélisation et la simulation numérique d’écoulements diphasiques compressibles. Dans ce contexte, les méthodes d’interfaces diffuses sont aujourd’hui bien acceptées. Cependant, un progrès est encore attendu en ce qui concerne la précision de la capture numérique de ces interfaces. Une nouvelle méthode est développée et permet de réduire significativement cette zone de capture. Cette méthode se place dans le contexte des méthodes numériques de type “MUSCL”, très employées dans les codes de production, et sur maillages non-structurés. Ces interfaces pouvant être le lieu où une transition de phase s’opère, celle-ci est considérée au travers d’un processus de relaxation des énergies libres de Gibbs. Un nouveau solveur de relaxation à thermodynamique rapide est développé et s’avère précis, rapide et robuste y compris lors du passage vers les limites monophasiques. En outre, par rapport aux applications industrielles envisagées, une extension de la thermodynamique des phases et du mélange est nécessaire. Une nouvelle équation d’état est développée en conséquence. La formulation est convexe et est basée sur l’équation d’état “Noble-Abel-Stiffened-Gas”. Enfin, sur un autre plan la dispersion de fluides non-miscibles sous l’effet de la gravité est également abordée. Cette problématique fait apparaître de larges échelles de temps et d’espace et motive le développement d’un nouveau modèle multi-fluide de type “shallow water bi-couche”. Sa résolution numérique est également traitéeThis manuscript addresses the theoretical modeling and numerical simulation of compressible two-phase flows. In this context, diffuse interface methods are now well-accepted but progress is still needed at the level of numerical accuracy regarding their capture. A new method is developed in this research work, that allows significant sharpening. This method can be placed in the framework of MUSCL-type schemes, widely used in production codes and on unstructured grids. Phase transition is addressed as well through a relaxation process relying on Gibbs free energies. A new instantaneous relaxation solver is developed and happens to be accurate, fast and robust. Moreover, in view of the intended industrial applications, an extension of the thermodynamics of the phases and of the mixture is necessary. A new equation of state is consequently developed. The formulation is convex and based on the “Noble-Abel-Stiffened-Gas” equation of state. In another context, the dispersion of non-miscible fluids under gravity effects is considered as well. This problematic involves large time and space scales and has motivated the development of a new multi-fluid model for “two-layer shallow water” flows. Its numerical resolution is treated as well
20
Mullaert, Chloé. "Étude mathématique des équations de Saint-Venant et de Navier-Stokes". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00825556.
Testo completoAbstract (sommario):
Cette thèse s'articule en deux parties. Dans la première, nous étudions les équations de Saint- Venant qui modélisent le comportement des océans, et de façon générale des fluides homogènes peu profonds, au voisinage de l'équateur dans le cadre d'une rotation rapide de la Terre. Grâce à ces hypothèses et aux équations de Navier-Stokes, nous commencerons par obtenir un modèle également connu sous le nom d' Equatorial Shallow Water System . Les équations obtenues font apparaître un paramètre de pénalisation " contenant les hypothèses de petitesse faites pour obtenir ce système simplifié. L'étude de la matrice de pénalisation permettra par une méthode de filtrage d'exhiber un système limite formel lorsque le paramètre " tend vers zéro pour lequel nous donnerons une condition nécessaire et su sante de globalité. Nous montrerons ensuite la convergence des solutions filtrées vers la solution du système limite. Dans la deuxième partie, nous exhiberons une classe de données initiales engendrant une solution globale aux équations de Navier-Stokes dans R3. En e et, les solutions de ces équations sont globales dans le cadre bidimensionnel mais dans le cas tridimensionnel, il faut rajouter, par exemple, des conditions su santes de petitesse des données initiales pour que la solution n'explose pas en temps ni. Nous prouverons que si on considère une donnée initiale ayant un spectre proche du plan horizontal alors elle engendre une solution globale des équations de Navier-Stokes. De plus, nous montrerons que, sous certaines hypothèses, la perturbation d'une donnée initiale engendrant une solution globale, par ce type de données au spectre quasi-horizontal, engendre encore une solution globale.
21
Kaar, Elizabeth Theresa. "Curvilinear systems modelling of pollutant transport in shallow waters". Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303625.
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22
Townsend, Philip James Andrew. "Numerical simulation of the shallow water equations coupled with a precipitation system driven by random forcing". Thesis, University of Sussex, 2018. http://sro.sussex.ac.uk/id/eprint/77216/.
Testo completoAbstract (sommario):
Quantification of flood risk and flood inundation requires accurate numerical simulations, both in terms of the mathematical theory that underpins the methods used and the manner in which the meteorological phenomena that cause flooding are coupled to such systems. Through our research, we have demonstrated how rainfall and infiltration effects can be incorporated into existing flood models in a rigorous and mathematically consistent manner; this approach departs from preceding methods, which neglect terms representing such phenomena in the conservation or balancing of momentum. We demonstrate how the omission of these terms means the solution derived from such models cannot a priori be assumed to be the correct one, which is in contrast to solutions from the extended system we have developed which respect the energetic consistency of the problem. The second issue we address is determining how we can model these meteorological phenomena that lead to flooding, with a specific interest in how existing observation data from rain gauges can be incorporated into our modelling approach. To capture the random nature of the precipitation, we use stochastic processes to model the complex meteorological interactions, and demonstrate how an accurate representation of the precipitation can be built. Given the specific industrial applications we have mind in regards to flood modelling and prediction, there will be a high computational cost associated with any such simulations, and so we consider techniques which can be used to reduce the computational cost whilst maintaining the accuracy of our solutions. Having such an accurate flood model, coupled with a stochastic weather model designed for efficient computational modelling, will enable us to make useful predictions on how future climate change and weather patterns will impact flood risk and flood damage.
23
Edwards, James Karlyle. "Assessment of Shallow Water Influence Minesweeping System (SWIMS) implementation utilizing CH-60". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1999. http://handle.dtic.mil/100.2/ADA374082.
Testo completoAbstract (sommario):
Thesis (M.S. in Operations Research) Naval Postgraduate School, December 1999."December 1999". Thesis advisor(s): Kneale T. Marshall. Includes bibliographical references (p. 87). Also available online.
24
Bachmann, Eric R. Gay David L. "Design and evaluation of an integrated GPS/INS system for shallow-water AUV Navigation /". Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1995. http://handle.dtic.mil/100.2/ADA304211.
Testo completoAbstract (sommario):
Thesis (M.S. in Computer Science) Naval Postgraduate School, September 1995."September 1995." Thesis advisor(s): Robert B. McGhee, D. Brutzman. Cover title: Design and evaluation of ... Navigation (SANS). Includes bibliographical reference (p. 217-220). Also available online.
25
Bachmann, Eric R., e David L. Gay. "Design and evaluation of an integrated GPS/INS system for shallow-water AUV Navigation". Thesis, Monterey, California. Naval Postgraduate School, 1995. http://hdl.handle.net/10945/35102.
Testo completoAbstract (sommario):
The major problem addressed by this research is the large and/or expensive equipment required by a conventional navigation system to accurately determine the position of an Autonomous Underwater Vehicle (AUV) during all phases of an underwater search or mapping mission. The approach taken was to prototype an integrated navigation system which combines Global Positioning System (OPS) and Inertial Measurement Unit (IMU), waterspeed and heading information using Kalman filtering techniques. Actual implementation was preceded by a computer simulation to test where the unit would fit into a larger hardware and software hierarchy of an AUV. The system was then evaluated in experiments which began with land based cart tests and progressed to open water trials where the unit was placed in a towed body behind a boat and alternately submerged and surfaced to provide periodic OPS updates to the Inertial Navigation System (INS). Test results and qualitative error estimates indicate that submerged navigation accuracy comparable to that of differential OPS may be attainable for periods of 30 seconds or more with low cost components of a small physical size.
26
Steven, Ruediger. "Simulation-based validation of navigation filter software for a shallow water AUV navigation system (SANS)". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA308153.
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Walker, Randy G. "Design and evaluation of an integrated, self-contained GPS/INS shallow-water AUV navigation system (SANS)". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1996. http://handle.dtic.mil/100.2/ADA313173.
Testo completoAbstract (sommario):
Thesis (M.S. in Electrical Engineering and M.S. in Computer Science) Naval Postgraduate School, June 1996."June 1996." Thesis advisor(s): Xiaoping Yun, Robert B. McGhee. Includes bibliographical references (p. 155-157). Also available online.
28
Karlen, David J. "The Biocomplexity of Benthic Communities Associated with a Shallow-water Hydrothermal System in Papua New Guinea". Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3652.
Testo completoAbstract (sommario):
Shallow-water hydrothermal vents occur world-wide in regions of volcanic activity. The vents located at Tutum Bay, Ambitle Island, Papua New Guinea are unique in that the vent fluids and surrounding sediments contain some of the highest concentrations of arsenic in a natural system. This study addresses the effects of the vent system on the benthic communities, focusing on the eukaryotes, macrofauna, meiofauna and bacteria.
Samples were collected in November 2003 and May/June 2005. Analysis of the 2003 macrofaunal samples indicated that pH, rather than arsenic was influencing the benthic community, and that the hydrothermal influence occurred at a greater distance than expected. Results of more intensive sampling carried out in 2005 are the primary focus of this dissertation.
The pore water and sediment characteristics revealed distinct physical habitats corresponding with distance from the vent. There was a trend of decreasing temperature and arsenic concentration and increasing salinity and pH with distance from the vent. The vent sediment was poorly sorted volcanic gravel, while sediments along the transect showed a gradient from fine, well sorted volcanic sands to coarser carbonate sands farther away.
The macrofauna showed a trend of increasing diversity with distance from the vent and similar taxa were present in both the 2003 and 2005 samples. The vent community was dominated by the polychaete Capitella cf. capitata. The inner transect
from 30 m to 140 m had low diversity. Dominant taxa included thalassinid shrimp and the amphipod Platyischnopus sp.A. The 180 m to 300 m sites had significantly higher diversity. The Danlum Bay reference site had relatively higher diversity than the nearshore transect sites and was dominated by deposit feeding polychaetes. Macrofaunal community structure was influenced by the sediment characteristics, notably by CaCO3 content, sorting and median grain size.
The meiofaunal community also showed changes with distance from the vent. Chromadorid nematodes were dominant at the vent site and were a major component of the meiofauna at most sites, along with copepods. The meiofaunal community at the reference site showed greater similarity to the vent community and both sites had low abundances. Nematodes were more abundant than copepods near the vent, but copepods were more abundant farther offshore and at the reference site. Meiofaunal community structure was influenced primarily by the pore water temperature and salinity. Biological interactions with the macrofaunal community through physical disturbance and predation may also influence the meiofaunal community.
The molecular analysis of eukaryotic and bacterial diversity also revealed changes with distance from the vent. The 0 m and reference sites grouped together due to the presence of fungal sequences and the 140 m and 300 m sites grouped together due to a common molluscan sequence. Metazoans and fungi dominated the eukaryote sequences. The most abundant eukaryotic OTUs included fungi matching Paecilomyces sp. and Cladosporium cladosporioides and metazoans matching Viscosia viscosa (Nematoda) and Astarte castanea
represented by 24 phyla and was dominated by Actinobacteria and γ-Proteobacteria. More bacterial phyla were present near the vent, while more overall OTUs were found at the intermediate sites along the transect. The most distant site had much lower diversity dominated by Firmicutes.
The macrofaunal community had the strongest correlation with environmental variables. Comparison between the meiofauna and the metazoan sequences showed the proportion of nematodes found in both datasets were comparable, but the meiofauna analysis found a higher proportion of arthropods, while the molecular results were disproportionally high for platyhelminthes.
Overall, the vents increased the complexity of the system by creating unique habitats. The extreme environment created by the hydrothermal activity maintained the surrounding habitat at an early successional stage colonized by a few opportunistic species. There was a gradation in the benthic communities away from the vent towards a more carbonate based climax community. The low pH environment had an effect on the sediment composition, which in turn influenced the benthic community. These findings can serve as a model for studying the potential effects of ocean acidification and climate change on benthic communities and marine biocomplexity.
29
Roberts, Ricky L. "Analysis, experimental evaluation, and software upgrade for attitude estimation by the Shallow-Water AUV Navigation System (SANS)". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA331860.
Testo completoAbstract (sommario):
Thesis (M.S. in Computer Science) Naval Postgraduate School, March 1997.Thesis advisor(s): Robert B. McGhee, Eric R. Bachmann. "March 1997." Includes bibliographical references (p. 185-188). Also available online.
30
Kostoulas, Christos. "Container vessel maneuvering model in shallow waters and assessment of maneuvering coefficients through system identification". Thesis, KTH, Marina system, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-223323.
Testo completoAbstract (sommario):
A vessel operating in the real world has to overcome wind, waves and ocean currents. The result of all the above is a motion of 6 degrees of freedom (DOF). Typically, for the maneuvering phase, the Newton-Euler equations are used to derive the equation of motion of the rigid body and the maneuvering theory to model the external forces and moments acting on a vessel. The main topic in this Master Thesis is to assess the maneuvering behavior of a specific container vessel through a 4DOF model. The purpose behind this study is to investigate the differences between the expected maneuvering behavior of the vessel and the operational one. To accomplish that, raw data from the vessel’s sea trials were used and a time domain simulation model created with the sway-roll yaw movements coupled and surge decoupled. The Son and No moto maneuvering model served as the base for the motion equations. The maneuvering coefficients (MC) were firstly estimated by semi-empirical formulas using the vessel particulars. The model was validated using the Esso Osaka sea trials data. The validation was limited to maneuvering parameters such as advance, tactical diameter, yaw overshoot angle etc. The final model was used on the sea trials data of the container vessel taking into consideration the wind forces through the Blender mann wind model. Moreover, correction factors for swallow water effects were used on the MC in order to provide a better accuracy and also to allow comparison between the operational data and the simulated ones since the sea trials depth could not be considered as deep waters. Finally, a system identification procedure was perfomed in order to investigate the possibility of identifying the exact MC values of a vessel. The results were encouraging. The simulation follows the patterns of the raw data relative accurately. In addition, the swallow water corrections provided enough evidence of the different behavior of the vessel depending on the depth under keel. From the SI side, a list of issues were encountered like parameter drift, multicollinearity and cost function prone to local minimum. A series of different procedures and algorithm proposed to overcome those difficulties and the results were promising.
31
Beklioglu, Meryem. "Whole lake and mesocosm studies on the role of nutrients and zooplankton grazing in a system of shallow and deep lakes". Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262384.
Testo completo
32
McCloskey, Bryan. "Foraminiferal responses to arsenic in a shallow-water hydrothermal system in papua new guinea and in the laboratory". [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002887.
Testo completo
33
Price, Roy E. "Biogeochemical Cycling of Arsenic in the Marine Shallow-water Hydrothermal System of Tutum Bay, Ambitle Island, Papua New Guinea". [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002437.
Testo completo
34
Smithson, Sheena Marie. "Dynamics of Interal Phosporus Cycling in a Highly Eutrophic, Shallow, Fresh Water Lake in Utah Lake State Park, Utah, USA". BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/9217.
Testo completoAbstract (sommario):
Eutrophication is an increasing global concern as human effluent saturates lakes with an over abundance of nutrients. Phosphorus, generally being the limiting nutrient, is often the most impactful, allowing cyanobacteria populations to grow out of control leading to harmful blooms that can produce cyanotoxins, anoxic lake conditions, and mass fish kills. Utah Lake, a shallow highly eutrophic fresh water lake located in central Utah Valley, has experienced these harmful algal blooms for the last several years. The internal phosphorus cycle is a significant driver in Utah Lake's eutrophication, as the sediments act as both a sink and a source for phosphorus. Most of the phosphorus originates from external sources, gets captured by the sediment, and then through several physiochemical and biological process, gets released back into the surface water as a self sustaining eutrophication system. To determine the effects of the different physiochemical processes that drive the internal phosphorus system, we incubated 72 total sediment cores taken from two locations, chosen to best represent the lake's chemical and spatial variability, under aerobic, anaerobic, pH=9.5 and pH=7 conditions with various P concentrations (ambient, 0.5X, 2X, 4X) taking water samples at 0, 12, 24, and 72 hours. Dissolved oxygen (DO), pH, soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP), and other major ions were measured for each sample. The highest P sediment release occurred under aerobic conditions, while the highest P sediment uptake occurred under anaerobic conditions. While pH did appear to have a mild effect on P flux, our study showed the lake has a remarkably stable bicarbonate buffer system making it unlikely that pH would contribute significantly under natural settings. Under all conditions the 2X and 4X cores experienced the highest P uptake, but final elevated P concentrations were still higher than initial ambient concentrations, indicating a probable delayed recovery time after external reductions occur.
35
Adim, Mahieddine. "Modèles continûment stratifiés et systèmes multi-couches pour les écoulements géophysiques". Electronic Thesis or Diss., Université de Rennes (2023-....), 2024. http://www.theses.fr/2024URENS026.
Testo completoAbstract (sommario):
Dans cette thèse, nous établissons rigoureusement des ponts entre les écoulements continument stratifiés et les écoulements multi-couches. Dans une première partie, nous considérons le système de Saint-Venant multi-couches avec un terme supplémentaire diffusif qui a un effet régularisant, dont la motivation provient des travaux des océanographes Gent & McWilliams sur le mélange isopycnal et la diffusivité des tourbillons, et qui pourrait être interprété comme un terme de turbulence. En exploitant la structure de ce système, nous obtenons un dictionnaire qui nous permet d'interpréter ce système multi-couches comme une discrétisation de la formulation en coordonnées isopycnales du système hydrostatique continument stratifié avec le terme diffusif de Gent & McWilliams ajouté de manière similaire. Nous montrons la convergence de la solution discrète vers la solution continue à mesure que le nombre de couches tend vers l'infini, et nous fournissons un taux de convergence explicite. Dans une deuxième partie, dans cette thèse, nous abordons la limite "inverse", nous montrons rigoureusement que, sous certaines conditions d'hyperbolicité et dans un cadre topologique bien choisi, la solution du système continument stratifié converge vers le système de Saint-Venant bi-couches dans la limite de stratification netteIn this thesis, we rigorously establish bridges between continuously stratified flows and multi-layer flows. In the first part, we consider the multi-layer shallow water system with an additional diffusive term that has a regularizing effect, motivated by the work of oceanographers Gent & McWilliams on isopycnal mixing and eddy diffusivity, which can be interpreted as a turbulence term. By exploiting the structure of this system, we derive a dictionary that allows us to interpret this multi-layer system as a discretization of the formulation in isopycnal coordinates of the continuously stratified hydrostatic system with the Gent & McWilliams diffusive term added in a similar manner. We demonstrate the convergence of the discrete solution to the continuous solution as the number of layers tends to infinity, and we provide an explicit convergence rate. In the second part of this thesis, we address the "inverse" limit. We rigorously show that, under certain hyperbolicity conditions and within a well-chosen topological framework, the solution of the continuously stratified system converges to the bi-layer shallow water system in the limit of sharp stratification
36
Pelli, Dario [Verfasser], e Hocine [Akademischer Betreuer] Oumeraci. "Nested modelling of wave processes from deep to shallow water: Building an operational wave model system / Dario Pelli ; Betreuer: Hocine Oumeraci". Braunschweig : Technische Universität Braunschweig, 2018. http://d-nb.info/1175387584/34.
Testo completo
37
Smith, Robert K. "The contour-advective semi-Lagrangian hybrid algorithm approach to weather forecasting and freely propagating inertia-gravity waves in the shallow-water system". Thesis, St Andrews, 2009. http://hdl.handle.net/10023/716.
Testo completo
38
Li, Yuepeng. "Development of an unstructured grid, finite volume eutrophication model for the shallow water coastal bay: Application in the Lynnhaven River Inlet system". W&M ScholarWorks, 2006. https://scholarworks.wm.edu/etd/1539616741.
Testo completoAbstract (sommario):
The shallow water region is an important portion of the estuarine and coastal waters, since it encompasses the entire land-water margin as the buffer zone and supports one of the most productive ecosystems. When light can penetrate to the sediment, it triggers the benthic microalgae community to perform photosynthesis, resulting in a benthic-pelagic exchange flux different from that of the deeper water. This study utilized the laboratory-measured benthic flux, and a suite of well-calibrated numerical models to examine the eutrophication process in the Lynnhaven River Inlet system with special emphasis on: the role played by benthic microalgae, and nutrient budgets (sources, sinks, and pathways) of the system. An unstructured grid hydrodynamic model UnTRIM developed for the shallow water environment was applied to the Lynnhaven to quantify the transport time scale and as the input for the water quality model. Based on the skill assessment result, it was clear that the presence of benthic microalgae is indispensable for an accurate and realistic calibration of the water quality model. Analysis of field samples in the laboratory experiments demonstrated that benthic microalgae performed photosynthesis under light conditions in surficial sediments, resulting in the net uptake of nutrients and the release of oxygen both to the overlying water column and down to the sediment. Based on the results of annual nutrient budgets, it was shown that the major external source for nitrogen and phosphorus was from nonpoint source loadings. There were three comparable sinks: export to the Bay, burial in the deep sediment, and ditrification in the case of nitrogen. One of the major pathways for nitrogen and phosphorus was the internal recycling. The regenerated dissolved nutrients that were recycled in the water column were more than two times larger than the current total nutrient external loadings. Sensitivity tests showed that, due to their retention capacity, benthic microalgae's presence could decrease the overall export to the Bay, enhance the internal recycling, and increase the denitrification rate in the sediment.
39
Karapinar, Burcu. "Role Of Hydrology, Sewage Effluent Diversion And Fish On Mass Balance Of Nutrients In A System Of Shallow Lakes Mogan And Eymir, Turkey". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606542/index.pdf.
Testo completoAbstract (sommario):
In this study, annual total phosphorus (TP) budget and dissolved inorganic nitrogen (DIN) load were constructed for Lakes Mogan and Eymir for the period of eight years from 1997 to 2004 and the period of ten years covering from 1993 to 1995 and 1997 to 2004, respectively.
Lake Mogan experienced seasonal and interannual water level fluctuations. Low water level experienced in 2001 led to decrease in the in-lake TP amount whereas 2-fold increase in the in-lake DIN amount was recorded. Also, high hydraulic residence time resulted in high TP and DIN amount in the lake. Increase in hydraulic residence time was due to management of the lake level. It seems that this practice deteriorates the water quality of Lake Mogan.
In Lake Eymir, sewage effluent diversion undertaken in 1995 resulted in 2-fold and 11-fold decrease in TP and DIN amounts in the lake, respectively. High biomass of carp and tench were halved through selective removal during 1998-1999. A 2.5-fold and 1.5 fold decrease in the in-lake TP and DIN amounts, respectively, were recorded after the biomanipulation. In low water level years, the in-lake TP increased and the in-lake DIN amounts were high despite the fact that TP and DIN loads via inflows were significantly low. Therefore, the results showed that the in-lake phosphorus and nitrogen amount were controlled by internal processes rather than external loading in the years with low water levels which coincided with the high hydraulic residence times.
40
Fischer, Jason L. "Evaluating Habitat Restoration in the St. Clair-Detroit River System". University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1576160707431634.
Testo completo
41
Rambaud, Amélie. "Modélisation, analyse mathématique et simulations numériques de quelques problèmes aux dérivées partielles multi-échelles". Phd thesis, Université Claude Bernard - Lyon I, 2011. http://tel.archives-ouvertes.fr/tel-00656013.
Testo completoAbstract (sommario):
Nous étudions plusieurs aspects d'équations aux dérivées partielles multi-échelles. Pour trois exemples, la présence de multiples échelles, spatiales ou temporelles, motive un travail de modélisation mathématique ou constitue un enjeu de discrétisation. La première partie est consacrée à la construction et l'étude d'un système multicouche de type Saint-Venant pour décrire un fluide à surface libre (océan). Son obtention s'appuie sur l'analyse des échelles spatiales, précisément l'hypothèse " eau peu profonde ". Nous justifions nos équations à partir du modèle primitif et montrons un résultat d'existence locale de solution. Puis nous proposons un schéma volumes finis et des simulations numériques. Nous étudions ensuite un problème hyperbolique de relaxation, inspiré de la théorie cinétique des gaz. Nous construisons un schéma numérique via une stratégie préservant l'asymptotique : nous montrons sa convergence pour toute valeur du paramètre de relaxation, ainsi que sa consistance avec le problème à l'équilibre local. Des estimations d'erreurs sont établies et des simulations numériques sont présentées. Enfin, nous étudions un problème d'écoulement sanguin dans une artère avec stent, modélisé par un système de Stokes dans un domaine contenant une petite rugosité périodique (géométrie double échelle). Pour éviter une discrétisation coûteuse du domaine rugueux (l'artère stentée), nous formulons un ansatz de développement de la solution type Chapman-Enskog, et obtenons une loi de paroi implicite sur le bord du domaine lisse (artère seule). Nous montrons des estimations d'erreurs et des simulations numériques
42
Baloochestani, Farshad. "Estimation of Hydraulic Properties of the Shallow Aquifer System for Selected Basins in the Blue Ridge and the Piedmont Physiographic Provinces of the Southeastern U.S. Using Streamflow Recession and Baseflow Data". Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/geosciences_diss/2.
Testo completoAbstract (sommario):
The objectives of this research are to measure the aquifer properties (S, T, and K) of selected watersheds delineated to the U.S. Geological Survey gauging stations using streamflow recession and baseflow data and to describe the relations among the properties of shallow aquifers and the physical properties of the basins, such as slope, regolith type and thickness, and land use type. Geographic Information System (GIS) techniques are utilized to investigate critical physiographic controls on transmissivity and storage coefficients on a regional basis. Moreover, the effect of evapotranspiration on recession index is illustrated. Finally, a detailed quantitative comparison of results for the Piedmont and the Blue Ridge Physiographic Provinces in southeast of the U.S. is provided. Recession index, annual groundwater recharge, and annual baseflow data were obtained from 44 USGS-gauging stations with drainage areas larger than 2 (mi2) and less than 400 (mi2). These gauging stations are located in Georgia and North Carolina. Analyses of data focused on GIS techniques to estimate watershed parameters such as total stream length, drainage density, groundwater slope, and aquifer half-width. The hydraulic diffusivity, transmissivity, and storage coefficient of watersheds were computed using hydrograph techniques and the Olmsted and Hely, and Rorabaugh mathematical models. Median recession index values for the Blue Ridge and Piedmont Provinces are 87.8 and 74.5 (d/log cycle), respectively. Median areal diffusivity values for the Blue Ridge and Piedmont are 35,000 and 44,200 (ft2/d), respectively. Median basin-specific estimates of transmissivity for basins in the Blue Ridge and Piedmont are 150 and 410 (ft2/d), respectively. The large values of transmissivity obtained for the Piedmont regolith may be attributed to the thick regolith, low values of basin relief, and voids that develop as a result of fracturing, foliation, weathering, and fractured quartz veins in the saprolite. Median basin-specific estimates of storage coefficient for basins in the Blue Ridge and Piedmont are 0.005 and 0.009, respectively. In general, the results from this study reveal great differences in basin-specific hydraulic parameters of the regolith material within the Piedmont compared to that of the Blue Ridge Physiographic Province.
43
RAMIREZ, CAROLINE. "Contribution à l'étude des ondes internes non-linéaires en milieu tournant". Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10221.
Testo completoAbstract (sommario):
Nous etudions a l'aide de la theorie de l'eau peu profonde une onde interne plane dans le contexte d'un fluide tournant stratifie en bicouche. Differents cas ont ete traites pour lesquels les hypotheses de faible ecart de densite entre les couches et de faibles epaisseurs de couches sont considerees independamment ou en meme temps. Nous apportons la demonstration qu'une equation d'ostrovsky gouverne les ondes internes non-lineaires d'interface dans le cas faiblement tournant. Nous demontrons que reduire l'ecart de densite conduit a augmenter les effets de la rotation. Enfin nous etablissons les equations qui gouvernent les ondes internes dans quelques cas particuliers et nous donnons la forme de celle-ci. Des experiences ont ete menees dans la grande cuve tournante du laboratoire coriolis pour etudier l'influence de la rotation sur des ondes internes axisymetriques. Nous avons mis en evidence quelques phenomenes interessant et les conclusions experimentales confirment nos resultats analytiques en ce qui concerne les influences respectives de l'ecart de densite et de la rotation. La rotation modifie considerablement les lois d'evolution de l'amplitude en fonction de la distance au centre de la cuve. Une autre partie de l'etude a ete consacree a la recherche experimentale de la generation des ondes internes non-lineaires par la maree en presence du talus continental ainsi que leur propagation. L'originalite de ce travail reside dans la generation d'ondes internes tridimensionnelles ainsi que dans la prise en compte des effets de la rotation sur le mecanisme de generation et la propagation des ondes. Nous avons montre que seul le jusant engendre la maree interne sur le plateau et le talus. La rotation n'agit pas sur le mecanisme de generation mais sur la propagation des ondes, de plus elle en diminue l'amplitude et en augmente la vitesse de propagation.
44
Trémolet, Yannick. "Parallélisation d'algorithmes variationnels d'assimilation de données en météorologie". Grenoble 1, 1995. http://www.theses.fr/1995GRE10211.
Testo completoAbstract (sommario):
Le probleme de l'assimilation de donnees sous sa forme generale peut se formuler: comment utiliser simultanement un modele theorique et des observations pour obtenir la meilleure prevision meteorologique ou oceanographique ?, sa resolution est tres couteuse, pour la prochaine generation de modeles elle necessitera une puissance de calcul de l'ordre de 10 tflops. A l'heure actuelle, aucun calculateur n'est capable de fournir de telles performances mais cela devrait etre possible dans quelques annees, en particulier grace aux ordinateurs paralleles a memoire distribuee. Mais, la programmation de ces machines reste un processus complique et on ne connait pas de methode generale pour paralleliser de maniere optimale un algorithme donne. Nous tenterons, de repondre au probleme de la parallelisation de l'assimilation de donnees variationnelle, ce qui nous conduira a etudier la parallelisation d'algorithmes numeriques d'optimisation assez generaux. Pour cela, nous etendrons la methodologie de l'ecriture des modeles adjoints au cas ou le modele direct est parallele avec echanges de messages explicites. Nous etudierons les differentes approches possibles pour paralleliser la resolution du probleme de l'assimilation de donnees: au niveau des modeles meteorologiques direct et adjoints, au niveau de l'algorithme d'optimisation ou enfin au niveau du probleme lui-meme. Cela nous conduira a transformer un probleme sequentiel d'optimisation sans contraintes en un ensemble de problemes d'optimisation relativement independants qui pourront etre resolus en parallele. Nous etudierons plusieurs variantes de ces trois approches tres generales et leur utilite dans le cadre du probleme de l'assimilation de donnees. Nous terminerons par l'application des methodes de parallelisation precedentes au modele de shallow water et comparerons leurs performances. Nous presenterons egalement une parallelisation du modele meteorologique arps (advanced regional prediction system)
45
Ramsamy, Priscilla. "Modélisation de la morphodynamique sédimentaire par une méthode distribuant le résidu". Thesis, Antilles, 2017. http://www.theses.fr/2017ANTI0206/document.
Testo completoAbstract (sommario):
Ce travail de thèse, propose un schéma numérique d'ordre élevé, distribuantle résidu (RD) pour l'approximation d'un problème hydro-sédimentairehyperbolique non conservatif, couplant les modèles de Grass et de Saint-Venant. Il fait appel à des méthodes de Runge-Kutta à variation totale diminuanteet de stabilisation (méthode de décentrement amont, dit Upwind),avec ou sans adjonction de limiteurs et présente de bonnes propriétés.L'une des facettes importantes de ce qui a été réalisée, repose sur la conceptionet le développement d'un programme Python 2D-espace, sous la formed'un logiciel faisant appel à un ensemble de modules créés pour l'occasion.Le développement du code de calcul, qui se propose d'approcher la solutiondu problème hydro-sédimentaire, a été e_ectué avec une orientation Objetet pour être e_cace sur calculateur parallèle (utilisant le parallélisme multithreadsOpenMP). L'une des particularités du schéma numérique dans cecadre, est liée à son application à des quadrangles.Un programme 1D-espace, qui se présente également sous forme de logiciel,a aussi été mis en place. Pour des raisons de portabilité et d'e_catité, il aété écrit multilangages (Python-Fortran : via numpy.ctypes pour Python etvia l'interface standard de Fortran pour C). Le schéma RD avec ou sansadjonction de limiteurs de _ux, a été implémenté à la manière d'un schémaprédicteur-correcteur. Des comparaisons avec d'autres schémas ont été e_ectuées a_n de montrer son e_cacité, son ordre de précision élevé a été mis enévidence, et la C-propriété a été testée. Les tests ont révélé que, pour le casd'un transport d'un pro_l sédimentaire parabolique, c'est le limiteur de _uxMUSCL MinMod, qui est le plus adapté parmi ceux testés.Dans le cas scalaire, des tests numériques ont été réalisés a_n de validerle second ordre de précisionThe present work, proposes a high order Residual Distribution (RD) numericalscheme to solve the non conservative hyperbolic problem, coupling Shallow Water and Grass equations. It uses Total Value Diminishing Runge Kutta and stabilisation Upwind methods, with or without limiters. It also has some good properties.A part of the work realised in this thesis, is about the conception and the developpement of a 2D-space Python program, under the form of a software,using a set of moduls created for the occasion. the code developpement, whichis said to approach the _uid-sediment model, coupling Shallow-Water and sedimentequations, has been made with an Object orientation and in orderto be e_cient on parallel architecture (using multithreads OpenMP parallelism). One of the features of the scheme in this case, is due to its application on quadrangles.A 1D-space program, also writen as a software, has been estabished. In order to be portable and e_cient, It has been developped multilinguals (Python- Fortran : by numpy.ctypes for Python and by standart interface FORTRAN for C). The RD scheme with or without Flux Limiters, has been implemented like predictor-corrector one. Comparisons with other schemes results have been realised, in order to show its e_ciency, moreover its high order accuracy has been focus on, and the C-proprerty has been tested. The tests show that MUSCL MinMod _ux limiters, is the most adaptated for a dune test case, between all tested.In the scalar case, numerical tests have been realised, for validating the secondorder of accuracy
46
Le, Minh Hoang. "Modélisation multi-échelle et simulation numérique de l’érosion des sols de la parcelle au bassin versant". Thesis, Orléans, 2012. http://www.theses.fr/2012ORLE2059/document.
Testo completoAbstract (sommario):
L’objectif global de ce travail est d’étudier une modélisation multi échelle et de développer une méthode adaptée pour la simulation numérique du processus d’érosion à l’échelle du bassin versant. Après avoir passé en revue les différents modèles existants, nous dérivons une solution analytique non triviale pour le système couplé modélisant le transport de sédiments par charriage. Ensuite, nous étudions l’hyperbolicité de ce système avec diverses lois de sédimentation proposées dans la littérature. Concernant le schéma numérique, nous présentons le domaine de validité de la méthode de splitting, pour les équations modélisant l’écoulement et celle décrivant l’évolution du fond. Pour la modélisation du transport en suspension à l’échelle de la parcelle, nous présentons un système d’équations couplant les mécanismes d’infiltration, de ruissellement et le transport de plusieurs classes de sédiments. L’implémentation et des tests de validation d’un schéma d’ordre élevé et de volumes finis bien équilibré sont également présentés. Ensuite, nous discutons sur l’application et la calibration du modèle avec des données expérimentales sur dix parcelles au Niger. Dans le but d’aboutir la simulation à l’échelle du bassin versant, nous développons une modélisation multi échelle dans laquelle nous intégrons le taux d’inondation dans les équations d’évolution afin de prendre en compte l’effet à petite échelle de la microtopographie. Au niveau numérique, nous étudions deux schémas bien équilibrés : le schéma de Roe basé sur un chemin conservatif, et le schéma avec reconstruction hydrostatique généralisée. Enfin, nous présentons une première application du modèle avec les données expérimentales du bassin versant de Ganspoel qui nécessite la parallélisation du codeThe overall objective of this thesis is to study a multiscale modelling and to develop a suitable method for the numerical simulation of soil erosion on catchment scale. After reviewing the various existing models, we derive an analytical solution for the non-trivial coupled system modelling the bedload transport. Next, we study the hyperbolicity of the system with different sedimentation laws found in the literature. Relating to the numerical method, we present the validity domain of the time splitting method, consisting in solving separately the Shallow-Water system (modelling the flow routing) during a first time step for a fixed bed and updating afterward the topography on a second step using the Exner equation. On the modelling of transport in suspension at the plot scale, we present a system coupling the mechanisms of infiltration, runoff and transport of several classes of sediment. Numerical implementation and validation tests of a high order wellbalanced finite volume scheme are also presented. Then, we discuss on the model application and calibration using experimental data on ten 1 m2 plots of crusted soil in Niger. In order to achieve the simulation at the catchment scale, we develop a multiscale modelling in which we integrate the inundation ratio in the evolution equations to take into account the small-scale effect of the microtopography. On the numerical method, we study two well-balanced schemes : the first one is the Roe scheme based on a path conservative, and the second one is the scheme using a generalized hydrostatic reconstruction. Finally, we present a first model application with experimental data of the Ganspoel catchment where the parallel computing is also motived
47
Uytendaal, AR. "Water clarity in two shallow lake systems of the Central Plateau, Tasmania, Australia". Thesis, 2006. https://eprints.utas.edu.au/22188/1/whole_UytendaalAdamRoman2006_thesis.pdf.
Testo completoAbstract (sommario):
Lake Crescent and Lake Sorell are two adjacent, large, shallow, mesotrophic lakes of
the Central Plateau, Tasmania, Australia. Both lakes are in the same catchment and
have similar geological and morphological characteristics. Early limnological work by
Cheng and Tyler found trophic characteristics to be substantially different, despite
their physical similarities. Historically, each lake exhibited strongly contrasting
'stable-states': Lake Sorell was a macrophyte-dominated clear water system, while
Lake Crescent was turbid and dominated by phytoplankton. Cheng and Tyler dubbed
this a "limnological paradox".
Since the late 1990s, the quality of the trout fishery declined, nutrient and algal
concentrations increased markedly and water clarity declined dramatically. These
changes coincided with unprecedented low water levels due primarily to severe
drought and competition for water by various users. The rapid decline in water clarity
prompted this investigation to determine the underlying processes responsible for the
degradation and to recommend management strategies to improve water quality.
Variables limiting light attenuation, turbidity and water clarity were measured from
April 2000 to August 2002, and modelled using multiple linear regression. Regression
coefficients were used to estimate the relative importance of each water quality
component, and this analysis showed that high levels of inorganic suspensoids were
largely responsible for the decline in water clarity. Although there were increases in
nutrients and suspended sediment in these lakes in the late 1990s, detailed analysis of
inputs to and outputs from these lakes suggested that these increases were derived
from internal sources as inputs from the surrounding catchment were negligible.
The historical record oflake levels was analysed to quantify the areas oflake bed that
would be in contact with the wave base under differing wind conditions and water
levels. This showed that both lakes were more prone to wind effects after 1998 owing
to the lower water levels. Further, prior to 1999 Lake Crescent was, on average, more
turbulent and more prone to wind-driven resuspension events than Lake Sorell, which
suggests a potential mechanism underlying Cheng and Tyler's "limnological
paradox".
The physical disturbance of sediments from wind-driven waves was further
investigated by calculating shear stress from wave theory, and quantifying
relationships between shear stress and suspended sediment concentration. Shear stress
characteristics across the lake basins were modelled under various lake levels and
wind speeds, and the magnitude of shear stress increased dramatically at lower lake
levels.
DYRESM-CAEDYM was used to develop a sediment resuspension model relating
wind, lake-level and sediment flux that was then calibrated and verified against field
observations. (The ecosystem model CAEDYM (ComputAtional Ecosystem
Dynamics Model) is coupled with the hydrodynamic driver DYRESM (DYnamic
REservoir Simulation Model) to accomplish these simulations). The model was used
to ascertain the benefits of managing water levels in the lakes to ameliorate the affects
of sediment resuspension and improve water quality. This modelling suggested that
the "degraded" state of the lakes from the late 1990s was initiated and sustained by
low lake levels leading to increased shear stress acting on the sediments. The
increased nutrient concentrations and algal biomass were also found to result from
low lake levels because external nutrient loading was insignificant. Conversely, the
modelling showed that raising water levels would dramatically improve water clarity.
Alternative, trophically-based explanations of the differences between lakes Crescent
and Sorell were examined by investigating the biotic interactions that influence water
quality and ecosystem function. The aim was to determine if trophic cascades and
stable-state theory would help explain the contrasting phycology of these two lakes.
The historical biological data from lakes Sorell and Crescent was reviewed and
reanalysed, and contemporary data collected to compare the trophic structure of the
"degraded" status at the end of the 1990s with the historical record. The strong
contrasts in phytoplankton productivity and community composition evident between
the lakes in the past were still prominent. The algal community of Lake Crescent has
concentrations up to 100 x those of Lake Sorell, and is still dominated by diatoms
while green algae dominate Lake Sorell. The zooplankton of Lake Crescent is dominated by small cladocerans and copepods, while Lake Sorell has more frequent
occurrences of larger cladocerans such as Daphnia. Lake Crescent also has an order
of magnitude greater biomass of the zooplanktivorous fish, Galaxias auratus, than
Lake Sorell, which leads to a much greater (up to 30 fold) predation pressure on large
zooplankters. By contrast the pattern in biomass of the introduced piscivorous brown
trout (Salmo trutta) between the two lakes is reversed. While some of these patterns
are consistent with differences in the nature of top-down trophic cascades between the
lakes, the accumulated evidence suggests that such relationships break down at the
link between zooplankton and phytoplankton.
The empirical evidence collected suggests that zooplankton grazing had little effect on
limiting phytoplankton productivity in either lake for any significant period of time,
while the greater dominance of meroplanktonic diatoms and the greater susceptibility
of Lake Crescent to wind-driven resuspension suggests a more parsimonious
explanation of the persistent phytoplankton dominance in this lake.
DYRESM-CAEDYM was then employed to investigate plankton and meroplankton
dynamics in lakes Sorell and Crescent, since this technique can be use to test 'N-P-Z'
(nutrients-phytoplankton-zooplankton) models. The hypothesis tested was that
developed above: that differences in resuspension combined with contrasts in the
proportions of meroplanktonic phytoplankton were sufficient to explain the
differences between the two lakes. Modelling of plankton and meroplankton dynamics
in both lakes returned significant contrasts in algal productivity that were driven
largely by contrasting sediment resuspension dynamics between the lakes.
It was concluded that the differing phytoplankton communities of the lakes are a
result of contrasting sediment resuspension dynamics between the lakes, with a
limited influence from contrasting levels of zooplankton grazing pressure.
48
Fountain, Matthew. "Nitrate transport in shallow flow systems at the Neuse River Waste Water Treatment Plant". 2006. http://www.lib.ncsu.edu/theses/available/etd-04112006-132437/unrestricted/etd.pdf.
Testo completo
49
Martinez, Monica Lucia. "A priori error estimates of finite element models of systems of shallow water equations". Thesis, 1998. http://hdl.handle.net/1911/19287.
Testo completoAbstract (sommario):
In recent years, there has been much interest in the numerical solution of shallow water equations. The numerical procedure used to solve the shallow water equations must resolve the physics of the problem without introducing spurious oscillations or excessive numerical diffusion. Staggered-grid finite difference methods have been used extensively in modeling surface flow without introducing spurious oscillations. Finite element methods, permitting a high degree of grid flexibility for complex geometries and facilitating grid refinement near land boundaries to resolve important processes, have become much more prevalent. However, early finite element simulations of shallow water systems were plagued by spurious oscillations and the various methods introduced to eliminate these oscillations through artificial diffusion were generally unsuccessful due to excessive damping of physical components of the solution.
Here, we give a brief overview on some finite element models of the shallow water equations, with particular attention given to the wave and characteristic formulations. In the literature, standard analysis, based on Fourier decompositions of these methods, has always neglected contributions from the nonlinear terms.
We derive ${\cal L}\sp{\infty} ((0,T); {\cal L}\sp2(\Omega))$ and ${\cal L}\sp2((0,T); {\cal H}\sp1(\Omega))$ a priori error estimates for both the continuous-time and discrete-time Galerkin approximation to the nonlinear wave model, finding these to be optimal in ${\cal H}\sp1(\Omega).$
Finally, we derive ${\cal L}\sp{\infty}((0,T); {\cal L}\sp2(\Omega))$ and ${\cal L}\sp2((0,T); {\cal H}\sp1(\Omega))$ a priori error estimates for our proposed Characteristic-Galerkin approximation to the nonlinear primitive model. We find these estimates to be optimal in ${\cal H}\sp1(\Omega)$ but with less restrictive time-step constraints when compared to the Galerkin estimates for the wave model.
50
Lai, Chia-yu, e 賴佳妤. "Nonlinear Hyperbolic Systems of Conservation Laws in Symmetric Space-Application to Shallow Water Equations". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/q69bh8.
Testo completoAbstract (sommario):
碩士國立中央大學
數學系
101
In this paper , we consider the following three dimension shallow water equations with Coriolis force then we derived the two dimension shallow water equation . And we transformed the two dimension shallow water equation 3by3 conservative system without source term . We can use the results in traditional hyperbolic systems of conservation laws to study the shock waves and rarefaction waves.