<p> A dissolved oxygen model for stratified lakes is developed and is verified for Lake Ontario. The processes affecting the dissolved oxygen budget of a lake including hydraulic inflow and outflow, production and decomposition, atmospheric reaeration, vertical transport across the thermocline, and sediment oxygen demand are analyzed and quantified. The production and decomposition oxygen fluxes are provided by a phosphorus model developed by others. These phosphorus-oxygen inter-relationships are quantified using stoichiometry developed for oceans. Nine years of temperature data for Lake Ontario are used to estimate the annual variations of epilimnetic temperatures, the rate of deepening of the epilimnion (i.e. thermocline depth vs time) and the vertical exchange coefficient. Dissolved oxygen data over a similar period are used to estimate lake-wide concentrations of DO. The vertical exchange and decomposition hypolimnetic oxygen fluxes are estimated from observed data. Model predictions of concentrations and fluxes compare favourably to the observed data. This provides some verification for the predictions of the oxygen model, the oxygen-phosphorus stoichiometry and the decomposition flux predicted by the phosphorus model.</p> / Thesis / Master of Engineering (MEngr)

No description available.

This thesis examines previously unresolved issues regarding the fluid dynamics of the spread of buoyant water into a rotating environment. We focus in particular on the role that finite potential vorticity and background turbulence play in determining the flow properties. When water of an anomalous density enters into an oceanic basin, gravity-driven surface flows can be established as a result of the density difference. These flows are often of a sufficiently large scale that the dynamics are affected by the Coriolis force arising from the rotation of the earth. This causes the formation of a large outflow gyre near to the source which feeds into a propagating gravity current that is confined to the coast. Previous experimental work in this field has sought to simplify the problem through the use of a point source and a quiescent ambient. We extend this work to provide a better representation of the real-world flow by introducing a source of finite depth and background turbulence to the rotating ambient. This study seeks to answer three key questions that are critical to the understanding of the flow behaviour in this scenario. First, what is the effect of the finite potential vorticity of the outflow on the properties of the outflow vortex and the boundary current? Second, what role does the presence of the the outflow vortex play in determining the behaviour of the current? Third, what is the effect of background turbulence on the flow properties? To carry out the investigation, experiments were conducted in the laboratory and compared with a theoretical description of the flow. The currents are generated inside a rotating tank filled with saltwater by the continuous release of buoyant freshwater from a source structure located at the fluid surface. A horizontal source of finite depth is used to introduce finite potential vorticity into the outflow. The impact of background turbulence is examined by introducing an oscillating grid into the rotating tank. We find that the finite potential vorticity of the outflow plays an important role in determining the flow properties for sufficiently low Rossby and Froude number. As the value of these parameters is increased a zero potential vorticity model is able to capture the key elements of the flow behaviour. The outflow vortex is found to act as a time-varying source to the boundary current, with the current velocity fixed by the vortex velocity field. The vortex vorticity is seen to decrease with time, while the vortex radius continues to increase at late times despite the vortex having reached a limiting depth, which enables potential vorticity to be conserved and the current to be supplied with a non-zero velocity. Finally, the structure of the background turbulence is found to be key in determining the effect that it has on the flow properties, with different behaviours observed for three-dimensional and quasi- two-dimensional turbulence.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present work had for objective to develop a simple process, with low cost and enough precise for its use in irrigation systems. The measurer consists of a secondary canalization provided with a hydrometer of low outflow installed in parallel with a singularity capable to provoke a pressure difference enters the extreme points of the device. The distinguishing pressure induces to the partial draining of the water through the secondary canalization being measured for the hydrometer. The work was developed in the Irrigation, Hydraulical and Draining laboratory of the Department of Agricultural Engineering of the Federal University of Santa Maria and in a system of water main for a central pivot installed in the Mayã Farm, in the city of São Sepé - RS. The work consists in the evaluation of a proportional measurer of volume (or outflow) and of the posterior application for the estimate of the volume of water fed for the system of bombardment to an expository of a system of irrigation of the type central pivot. The proportional measurer presents easiness about the construction and installation in the field. The results allowed concluding that the proportional measurer was capable to estimate the outflow of the central pivot irrigation system. The proportional measurer can be installed and operated in a simple way, and its components are of easy acquisition and low cost and maintenance. Such characteristics assume great importance in the current days becoming viable the implantation of systems of measurement in all the existing systems of irrigation in the agricultural way. / O presente trabalho teve por objetivo desenvolver um processo simples, de baixo custo e suficientemente preciso para a sua utilização em sistemas de irrigação. O medidor consiste de uma canalização secundária provida de um hidrômetro de baixa vazão instalada em paralelo com uma singularidade capaz de provocar uma diferença de pressão entre os pontos extremos do dispositivo. A pressão diferencial induz ao escoamento parcial da água através da canalização secundária sendo medida pelo hidrômetro. O trabalho foi desenvolvido no laboratório de Hidráulica, Irrigação e Drenagem do Departamento de Engenharia Rural da Universidade Federal de Santa Maria e em um sistema de bombeamento para adução de água para um pivô central na instalado na Fazenda Mayã, município de São Sepé RS. O trabalho consta da avaliação de um medidor de volume (ou de vazão) proporcional e da posterior aplicação para a estimativa do volume de água alimentado pelo sistema de bombeamento a uma adutora de um sistema de irrigação do tipo pivô central. O medidor proporcional apresenta facilidade quanto à sua construção e instalação no campo. Os resultados obtidos permitiram concluir que o medidor proporcional foi capaz de estimar com precisão a vazão da adutora de alimentação de um sistema de irrigação do tipo pivô central. O medidor proporcional pode ser instalado e operado de modo simples, sendo que seus componentes são de fácil aquisição e de baixo custo e manutenção. Tais características assumem grande importância nos dias atuais contribuindo para a implantação de sistemas de medição em todos os sistemas de irrigação existentes no meio rural.

<p>The trabecular meshwork (TM) is comparable to a bioactive filter that plays a major role in regulating outflow of aqueous humor of the eye and setting intraocular pressure (IOP). TM dysfunction may lead to ocular hypertension which is the major risk factor in glaucoma. Although the outflow properties of the TM have been assessed over the last sixty years, very little work has been done assessing its mechanical properties. Therefore, the major goals of these studies were two-fold: (1) to determine the relationship between mechanical properties of TM, specifically the bulk Young's modulus, and outflow function in normal and glaucomatous eyes, and (2) to establish a method and possible animal model for future testing of this relationship.</p><p>Outflow function was assessed by constant pressure perfusion in enucleated eyes at four pressure levels (10, 20, 30, and 40 mmHg) to determine outflow facilities and variability in outflow resistance with pressure elevation. A micro-strain analyzer (MSA) was used to determine the circumferential bulk Young's modulus of the TM post-perfusion. Based on their relative ease of availability, pigs and rats were explored as possible animal models. Due to the small size of rat eyes, atomic force microscopy (AFM) was used to assess the Young's modulus of TM rather than with a MSA.</p><p>We found that there was a relationship with better outflow function and a stiffer TM in normal eyes. Additionally, glaucomatous TM was found to be much softer and more variable than normal TM. Unfortunately, porcine TM did not serve as a good model for the bulk Young's modulus of human TM, presumably due to anatomical difference in its outflow pathway. Lastly, we were able to establish a new method for measuring the Young's modulus of rat TM for future work to determine potential mechanism for evaluating stiffness changes that may be associated with glaucoma.</p> / Dissertation

<div>Incompressible single-phase and two-phase flows are widely encountered in and underlie many engineering applications. In this thesis, we aim to develop efficient methods and algorithms for numerical simulations of these classes of problems. Specically, we present two schemes: (1) a modied consistent splitting scheme for incompressible single-phase flows with open/out flow boundaries; (2) a three-dimensional hybrid spectral element-Fourier spectral method for wall-bounded two-phase flows.</div><div><br></div><div><div>In the first part of this thesis, we present a modied consistent splitting type scheme together with a family of energy stable outflow boundary conditions for incompressible single-phase outflow simulations. The key distinction of this scheme lies</div><div>in the algorithmic reformulation of the viscous term, which enables the simulation of outflow problems on severely-truncated domains at moderate to high Reynolds numbers. In contrast, the standard consistent splitting scheme is observed to exhibit a numerical instability even at relatively low Reynolds numbers, and this numerical instability is in addition to the backflow instability commonly known to be associated with strong vortices or backflows at the outflow boundary. Extensive numerical experiments are presented for a range of Reynolds numbers to demonstrate the effectiveness and accuracy of the proposed algorithm for this class of flows.</div></div><div><br></div><div><div>In the second part of this thesis, we present a numerical algorithm within the phase-field framework for simulating three-dimensional (3D) incompressible two-phase flows in flow domains with one homogeneous direction. In this numerical method, we represent the flow variables using Fourier spectral expansions along the homogeneous direction and C0 spectral element expansions in the other directions. This is followed by using fast Fourier transforms so that the solution to the 3D problem is obtained by solving a set of decoupled equations about the Fourier modes for each flow variable. The computations for solving these decoupled equations are performed in parallel to effciently simulate the 3D two-phase</div><div>ows. Extensive numerical experiments are presented to demonstrate the performance and the capabilities of the scheme in simulating this class of flows.</div></div>

Made available in DSpace on 2017-07-10T19:24:03Z (GMT). No. of bitstreams: 1 Kayla Walquiria Garmus Poletto.pdf: 11373984 bytes, checksum: 4001fb7e0acd1d130237b83ee319f68d (MD5) Previous issue date: 2008-04-04 / Knowledge of the hydro-sedimentologic behavior of a river basin is basic for the appropriate management and use of their water resources. This work objectified to implement a study about the behavior of suspended-sediment discharge along the basin of false San Francisco River. Based on the available hydrosedimentometric data, had been generated rating-curve of the sediments concentration and outflow; reading of turbid?metro and outflow; reading of turbid?metro and concentration of sediment, and, afterwards, the measurements values of the daily outflow were converted into suspended-sediments discharge. The station of the basin presented daily average outflow of 4,81 m?/s an average suspended-sediment flow about 7,23 ton.day ?&#1470;, what it corresponds to a value of a specific suspended sediment load de 5 t.ano?&#1470;.km?. Also the physiographic characterization of the Basin of the False San Francisco River. / O conhecimento do comportamento hidrossedimentol?gico de uma bacia hidrogr?fica ? fundamental para a adequada gest?o e uso de seus recursos h?dricos. Este trabalho objetivou a elabora??o de estudo sobre o comportamento do fluxo de sedimentos em suspens?o ao longo da Bacia do Rio S?o Francisco Falso. Com base nos dados hidrossedimentom?tricos, foram geradas curvas-chave de concentra??o de sedimentos e vaz?o; leitura do turbid?metro e vaz?o; leitura do turbid?metro e concentra??o de sedimento, e, posteriormente, os valores de medi??es das vaz?es di?rias foram convertidos em valores de descarga s?lida em suspens?o. A esta??o da bacia apresentou vaz?o m?dia di?ria de 4,81 m?/s e um fluxo m?dio de sedimentos em suspens?o de aproximadamente 7,23 t.dia?&#1470;, o que corresponde a um valor de descarga s?lida espec?fica em suspens?o de 5 t.ano?&#1470;.km?. Tamb?m foi elaborada a caracteriza??o fisiogr?fica da Bacia do Rio S?o Francisco Falso.

Made available in DSpace on 2017-05-12T14:47:18Z (GMT). No. of bitstreams: 1 Kayla Walquiria Garmus Poletto.pdf: 11373984 bytes, checksum: 4001fb7e0acd1d130237b83ee319f68d (MD5) Previous issue date: 2008-04-04 / Knowledge of the hydro-sedimentologic behavior of a river basin is basic for the appropriate management and use of their water resources. This work objectified to implement a study about the behavior of suspended-sediment discharge along the basin of false San Francisco River. Based on the available hydrosedimentometric data, had been generated rating-curve of the sediments concentration and outflow; reading of turbid?metro and outflow; reading of turbid?metro and concentration of sediment, and, afterwards, the measurements values of the daily outflow were converted into suspended-sediments discharge. The station of the basin presented daily average outflow of 4,81 m?/s an average suspended-sediment flow about 7,23 ton.day ?&#1470;, what it corresponds to a value of a specific suspended sediment load de 5 t.ano?&#1470;.km?. Also the physiographic characterization of the Basin of the False San Francisco River. / O conhecimento do comportamento hidrossedimentol?gico de uma bacia hidrogr?fica ? fundamental para a adequada gest?o e uso de seus recursos h?dricos. Este trabalho objetivou a elabora??o de estudo sobre o comportamento do fluxo de sedimentos em suspens?o ao longo da Bacia do Rio S?o Francisco Falso. Com base nos dados hidrossedimentom?tricos, foram geradas curvas-chave de concentra??o de sedimentos e vaz?o; leitura do turbid?metro e vaz?o; leitura do turbid?metro e concentra??o de sedimento, e, posteriormente, os valores de medi??es das vaz?es di?rias foram convertidos em valores de descarga s?lida em suspens?o. A esta??o da bacia apresentou vaz?o m?dia di?ria de 4,81 m?/s e um fluxo m?dio de sedimentos em suspens?o de aproximadamente 7,23 t.dia?&#1470;, o que corresponde a um valor de descarga s?lida espec?fica em suspens?o de 5 t.ano?&#1470;.km?. Tamb?m foi elaborada a caracteriza??o fisiogr?fica da Bacia do Rio S?o Francisco Falso.

Abstract Crater counting is a method which allows us to estimate the surface ages of the planetary bodies, from which the sampling and sample delivery to laboratories on Earth are difficult or impossible. Because the number of craters on a surface unit increases over the time the surface has been exposed to space, old, geologically stable units have more craters than young and active units. When the crater production rate as a function of time is known, the absolute age of the surface unit can be determined based on its crater density. The purpose of this thesis is to investigate the role of small impact craters in crater counts to find out how modern very high-resolution space images can be utilized in age determination of planetary surfaces. The thesis focuses on how reliable crater count based datings are, if only small craters and counting areas are used in age determination. The research is carried out by utilizing crater counts on the outflow channels of Dao, Niger, Harmakhis and Reull Valles, which all are located in the eastern rim region of the Hellas impact basin, on the southern hemisphere of Mars. Crater counts are performed mainly based on the images of ConTeXt Imager (CTX) and High Resolution Imaging Science Experiment (HiRISE) aboard Mars Reconnaissance Orbiter (MRO). The results show that small craters are a very valuable tool to get information about the surface age. Instead of the size-range of counted craters, or the size of counting areas, results are dependent on the variability and scale of the surface modification history. The more variable or larger scale the modification history is, the larger surface area and wider crater diameter range are typically needed to achieve comprehensive age estimations. The crater counts on the eastern Hellas outflow channels support the earlier theories according to which the valles formed during a relatively short time interval, ~ 3.4–3.7 Ga ago. The existence of terrace structures and smaller tributary channels indicate that the outflow channels were filled by several pulses of liquids. The major fluvial activity ended no later than ~ 0.8–1.9 Ga ago, and it was probably controlled by the activity of nearby highland volcanoes. Soon after the declined fluvial activity, the outflow channels were covered by ice-rich deposits. The major reason for this was probably the changed climatic conditions, although in places e.g. impact cratering seems to have contributed to the emplacement of the deposits. The region as a whole was also resurfaced several times because of changes in local climate conditions. The most significant of the resurfacing processes seem to be the episodes of thin ice-rich mantling deposits, the most recent of which dominated the regional modification less than 10 Ma ago. In addition, the region has experienced eolian activity during the last 1 Ma. / Original papers The original publications are not included in the electronic version of the dissertation. Kostama, V.-P., Kukkonen, S., &amp; Raitala, J. (2017). Resurfacing event observed in Morpheos basin (Eridania Planitia) and the implications to the formation and timing of Waikato and Reull Valles, Mars. Planetary and Space Science, 140, 35–48. https://doi.org/10.1016/j.pss.2017.04.001 Kukkonen, S., &amp; Kostama, V.-P. (2018). Modification history of the Harmakhis Vallis outflow channel, Mars, based on CTX-scale photogeologic mapping and crater count dating. Icarus, 299, 46–67. https://doi.org/10.1016/j.icarus.2017.07.014 Kukkonen, S., &amp; Kostama, V.-P. (2018). Usability of small impact craters on small surface areas in crater count dating: Analysing examples from the Harmakhis Vallis outflow channel, Mars. Icarus, 305, 33–49. https://doi.org/10.1016/j.icarus.2018.01.004 Kukkonen, S., &amp; Kostama, V.-P. (2018). Mapping and dating based evolution studies of the Niger Vallis outflow channel, Mars. Planetary and Space Science, 153, 54–71. https://doi.org/10.1016/j.pss.2017.12.012 Korteniemi, J., &amp; Kukkonen, S. (2018). Volcanic Structures Within Niger and Dao Valles, Mars, and Implications for Outflow Channel Evolution and Hellas Basin Rim Development. Geophysical Research Letters, 45(7), 2934–2944. https://doi.org/10.1002/2018gl077067 http://jultika.oulu.fi/Record/nbnfi-fe201902226008

Glaucoma affects tens of millions of people and is the leading cause of irreversible blindness worldwide. Virtually all current glaucoma therapies target elevated intraocular pressure (IOP); however, the contribution of intracranial pressure (ICP) to glaucoma has recently garnered interest. Strain at the optic nerve head is now known to depend on the translaminar pressure difference (TLPD), which is the difference between IOP and ICP, rather than IOP alone. A better understanding of how IOP and ICP relate to glaucoma development and progression is essential for developing improved therapies and diagnostic tests. Glaucoma is commonly modeled in rats, yet aqueous humor dynamics are not well-documented in healthy nor diseased rat eyes. Moreover, because rats do not develop glaucoma spontaneously, it is essential to develop low-cost, reliable, and relevant models of glaucomatous pathology in the animal. The purpose of this dissertation work is to achieve the following goals: i) quantitatively assess aqueous humor dynamics in healthy, living rat eyes, ii) develop an ideal model of experimental glaucoma in rats, iii) quantitatively characterize aqueous humor dynamics throughout experimental glaucoma in living rats, and iv) investigate the effects of ICP manipulations on aqueous humor dynamics in living rats. Chapter 2 reports physiological parameters of aqueous humor dynamics for the first time in the eyes of living, healthy Brown-Norway rats, and presents a novel perfusion technique for efficiently and accurately estimating these parameters. Chapter 3 introduces the constant-pressure perfusion model of experimental glaucoma: a powerful new model which overcomes several limitations of existing techniques. The constant-pressure perfusion model induces IOP elevations which are prescribable and easily manipulated, does not directly target the trabecular meshwork or its vasculature, and offers continuous records of IOP rather than requiring regular animal handling and tonometry. Chapter 3 characterizes IOP-induced optic neuropathies in rats and demonstrates their resemblance to human glaucoma. Chapter 4 evaluates whether the constant-pressure perfusion model affects ocular physiology, specifically showing that resting IOP and conventional outflow facility are not permanently nor significantly altered in the model. Chapter 5 examines the effect of ICP manipulations on aqueous outflow physiology in living rats, and reports for the first time a graded effect of intracranial hypertension on conventional outflow facility. Evidence for a neural feedback mechanism that may serve to regulate the TLPD is also presented. Chapter 6 summarizes the results of this dissertation, provides recommendations for future work, and gives closing remarks. These collective projects provide insight into IOP regulation in both healthy and diseased rat eyes, advancing our understanding of glaucomatous development and damage in rats. A novel model of experimental glaucoma and several perfusion systems have been developed which are distinctly tailored for use in future glaucoma studies and will allow future investigators to study the disease with enhanced efficiency and exactitude. The results of this dissertation work suggest that detecting and correcting impairments of either IOP or ICP homeostatic capabilities may be of utmost importance for improving clinical outcomes in human glaucoma.