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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
511

Uma abordagem para determinação das pressões junto ao fundo de dissipadores de energia por ressalto hidráulico

Prá, Mauricio Dai January 2011 (has links)
O dimensionamento seguro e econômico de dissipadores de energia por ressalto hidráulico formado a jusante de vertedouros passa pela compreensão de como se processa a dinâmica do escoamento. Para que isso seja possível é necessário que sejam identificadas as características macroturbulentas do escoamento, tanto no que diz respeito aos valores médios quanto às parcelas flutuantes e extremas dos esforços de pressões atuantes junto ao fundo. Este trabalho, então, propõe a análise dos esforços hidrodinâmicos atuantes na estrutura hidráulica a partir de uma nova abordagem que preconiza que os esforços atuantes junto ao fundo devem ser avaliados como um somatório dos efeitos hidrodinâmicos ocasionados pelas distintas condições do escoamento. Dessa forma, foram avaliados individualmente os efeitos: (i) da curva de concordância vertical entre o perfil vertente e a bacia de dissipação e a sua influência sobre esta, (ii) do escoamento em regime rápido sobre um plano horizontal, (iii) da macroturbulência presente no ressalto hidráulico livre (tipo A) e (iv) do afogamento do ressalto hidráulico. Essa avaliação individualizada proporciona, em última instância, a identificação global dos esforços atuantes junto à estrutura hidráulica, conferindo sensibilidade a esta análise global a partir da identificação da influência de cada um dos efeitos atuantes e das respectivas consequências sobre a bacia de dissipação. O trabalho apresenta, assim, um método analítico de previsão de pressões médias, flutuantes e extremas atuantes ao longo de uma bacia de dissipação por ressalto hidráulico, quer este seja formado integralmente na bacia de dissipação, quer este seja formado parcialmente sobre o perfil vertente, condição predominante na operação de sistemas estruturais de dissipação de energia hidráulica. / To safely and economically design hydraulic jump energy dissipators downstream spillways the comprehension of the flow dynamics is needed. To achieve this it is needed to identify the macroturbulent characteristics of the flow, both the mean pressure values as well as the fluctuating and extreme pressures acting on the floor of the stilling basin. The present work proposes to analyze the hydrodynamic forces acting on the structures by means of a new approach which states that the pressures acting on the basin floor can be evaluates as the sum of hydrodynamic effects caused by the distinct flow conditions. The following effects were individually evaluated (i) transition from the spillway slope to the flat basin slope. (ii) supercrítical flow over a flat slope, (iii) macroturbulence present in a classic hydraulic jump (type A jump) and (iv) jump submergence. This individualized evaluation aims to identify the global forces acting on the spillway structure conferring sensitivity to the global analysis from the identification of each of the acting effects and its consequences. The present work relates an analytical method for predicting of mean, fluctuating and extreme pressures acting on a hydraulic jump stilling basin, be it formed integrally on the structure or partially over the spillway, usual condition in the basin operation.
512

Effects of repetitive, small magnitude earthquakes on groundwater chemistry in Faulkner County, Arkansas

Waggoner, Sarah Elizabeth 01 May 2011 (has links)
The drive to find reliable sources of fuel that follow our green concerns and reduce our dependence on foreign sources of fossil fuels has pushed exploration and recovery of natural gas from within the United States to a top priority. Earthquakes generated from the use of hydraulic fracturing techniques and/or use of high pressure injection wells are occurring at an alarming rate due to increases in hydrocarbon exploration and recovery. While the link between earthquakes and hydrocarbon production is still uncertain, earthquake induced changes to groundwater chemistry are clear. Yet it has not been determined if repetitive, smaller earthquakes, i.e. earthquakes with magnitudes less than Mw<4.5, can result in similar disturbances to water chemistry as the more significant events have been proven to cause. Two known earthquake swarms, each having repetitive, small earthquake events, occurred in an intraplate setting in Faulkner County, Arkansas. Testing for groundwater chemical changes related to the timing of earthquake events and total energy released show that small earthquakes indeed create changes to groundwater chemistry most probably due to fluid intrusion from deep, chloride, calcium, and magnesium rich waters. The reduction of the United States dependence on foreign sources or finding green sources of fuel should not be the only mitigating factor for our decisions concerning our natural resources.
513

Uma abordagem para determinação das pressões junto ao fundo de dissipadores de energia por ressalto hidráulico

Prá, Mauricio Dai January 2011 (has links)
O dimensionamento seguro e econômico de dissipadores de energia por ressalto hidráulico formado a jusante de vertedouros passa pela compreensão de como se processa a dinâmica do escoamento. Para que isso seja possível é necessário que sejam identificadas as características macroturbulentas do escoamento, tanto no que diz respeito aos valores médios quanto às parcelas flutuantes e extremas dos esforços de pressões atuantes junto ao fundo. Este trabalho, então, propõe a análise dos esforços hidrodinâmicos atuantes na estrutura hidráulica a partir de uma nova abordagem que preconiza que os esforços atuantes junto ao fundo devem ser avaliados como um somatório dos efeitos hidrodinâmicos ocasionados pelas distintas condições do escoamento. Dessa forma, foram avaliados individualmente os efeitos: (i) da curva de concordância vertical entre o perfil vertente e a bacia de dissipação e a sua influência sobre esta, (ii) do escoamento em regime rápido sobre um plano horizontal, (iii) da macroturbulência presente no ressalto hidráulico livre (tipo A) e (iv) do afogamento do ressalto hidráulico. Essa avaliação individualizada proporciona, em última instância, a identificação global dos esforços atuantes junto à estrutura hidráulica, conferindo sensibilidade a esta análise global a partir da identificação da influência de cada um dos efeitos atuantes e das respectivas consequências sobre a bacia de dissipação. O trabalho apresenta, assim, um método analítico de previsão de pressões médias, flutuantes e extremas atuantes ao longo de uma bacia de dissipação por ressalto hidráulico, quer este seja formado integralmente na bacia de dissipação, quer este seja formado parcialmente sobre o perfil vertente, condição predominante na operação de sistemas estruturais de dissipação de energia hidráulica. / To safely and economically design hydraulic jump energy dissipators downstream spillways the comprehension of the flow dynamics is needed. To achieve this it is needed to identify the macroturbulent characteristics of the flow, both the mean pressure values as well as the fluctuating and extreme pressures acting on the floor of the stilling basin. The present work proposes to analyze the hydrodynamic forces acting on the structures by means of a new approach which states that the pressures acting on the basin floor can be evaluates as the sum of hydrodynamic effects caused by the distinct flow conditions. The following effects were individually evaluated (i) transition from the spillway slope to the flat basin slope. (ii) supercrítical flow over a flat slope, (iii) macroturbulence present in a classic hydraulic jump (type A jump) and (iv) jump submergence. This individualized evaluation aims to identify the global forces acting on the spillway structure conferring sensitivity to the global analysis from the identification of each of the acting effects and its consequences. The present work relates an analytical method for predicting of mean, fluctuating and extreme pressures acting on a hydraulic jump stilling basin, be it formed integrally on the structure or partially over the spillway, usual condition in the basin operation.
514

Uma abordagem para determinação das pressões junto ao fundo de dissipadores de energia por ressalto hidráulico

Prá, Mauricio Dai January 2011 (has links)
O dimensionamento seguro e econômico de dissipadores de energia por ressalto hidráulico formado a jusante de vertedouros passa pela compreensão de como se processa a dinâmica do escoamento. Para que isso seja possível é necessário que sejam identificadas as características macroturbulentas do escoamento, tanto no que diz respeito aos valores médios quanto às parcelas flutuantes e extremas dos esforços de pressões atuantes junto ao fundo. Este trabalho, então, propõe a análise dos esforços hidrodinâmicos atuantes na estrutura hidráulica a partir de uma nova abordagem que preconiza que os esforços atuantes junto ao fundo devem ser avaliados como um somatório dos efeitos hidrodinâmicos ocasionados pelas distintas condições do escoamento. Dessa forma, foram avaliados individualmente os efeitos: (i) da curva de concordância vertical entre o perfil vertente e a bacia de dissipação e a sua influência sobre esta, (ii) do escoamento em regime rápido sobre um plano horizontal, (iii) da macroturbulência presente no ressalto hidráulico livre (tipo A) e (iv) do afogamento do ressalto hidráulico. Essa avaliação individualizada proporciona, em última instância, a identificação global dos esforços atuantes junto à estrutura hidráulica, conferindo sensibilidade a esta análise global a partir da identificação da influência de cada um dos efeitos atuantes e das respectivas consequências sobre a bacia de dissipação. O trabalho apresenta, assim, um método analítico de previsão de pressões médias, flutuantes e extremas atuantes ao longo de uma bacia de dissipação por ressalto hidráulico, quer este seja formado integralmente na bacia de dissipação, quer este seja formado parcialmente sobre o perfil vertente, condição predominante na operação de sistemas estruturais de dissipação de energia hidráulica. / To safely and economically design hydraulic jump energy dissipators downstream spillways the comprehension of the flow dynamics is needed. To achieve this it is needed to identify the macroturbulent characteristics of the flow, both the mean pressure values as well as the fluctuating and extreme pressures acting on the floor of the stilling basin. The present work proposes to analyze the hydrodynamic forces acting on the structures by means of a new approach which states that the pressures acting on the basin floor can be evaluates as the sum of hydrodynamic effects caused by the distinct flow conditions. The following effects were individually evaluated (i) transition from the spillway slope to the flat basin slope. (ii) supercrítical flow over a flat slope, (iii) macroturbulence present in a classic hydraulic jump (type A jump) and (iv) jump submergence. This individualized evaluation aims to identify the global forces acting on the spillway structure conferring sensitivity to the global analysis from the identification of each of the acting effects and its consequences. The present work relates an analytical method for predicting of mean, fluctuating and extreme pressures acting on a hydraulic jump stilling basin, be it formed integrally on the structure or partially over the spillway, usual condition in the basin operation.
515

Estudo experimental de uma bomba de solução rica em refrigerador por absorção operando pela diferença de pressão do refrigerador / Experimental study of one pump of rich solution in refrigerator for absorption operation for the difference of pressure of the refrigerator

Quinteros Panesi, Andre Ricardo 28 February 2005 (has links)
Orientador: Jose Ricardo Figueiredo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T09:31:53Z (GMT). No. of bitstreams: 1 QuinterosPanesi_AndreRicardo_M.pdf: 5200860 bytes, checksum: 50a776e6a73c01814b4bfb64919bb6d7 (MD5) Previous issue date: 2005 / Resumo: Foi projetada e construída uma bomba de diafragma para um sistema de refrigeração por absorção de água-amônia que opera empregando vapor expandido entre os mesmos níveis de pressão de bombeamento. Através de uma bancada experimental, verificaram-se as condições de funcionamento da bomba que simula um sistema de absorção nas fases de sucção e recalque da solução água-amônia do absorvedor para o gerador através de um nível de baixa pressão para um nível de alta pressão. No teste utilizou-se um recipiente contendo água sujeito a baixa pressão no reservatório representando o absorvedor, um cilindro hermético a alta pressão com entradas e saídas necessárias para a tomada de ar e água representando o gerador, um compressor de ar para pressurização do sistema e dispositivos de controle e comando para a automação do sistema. Foi demonstrada a viabilidade de operação do equipamento como também as limitações encontradas do protótipo / Abstract: Was projected and constructed one diaphragm pump for one system of refrigeration for water-ammonia absorption that operates using expanded vapor it enters the same levels of pump action pressure. Through an experimental group of benches, the conditions of functioning of the pump had been verified that simulates a system of absorption in the suction phases and stresses of the solution water-ammonia of the absorber for the generator through an leveI of low pressure for an high-pressure leveI. In the test one container was used contains water subject to lowers pressure in the reservoir representing the absorber, an air-tight cylinder the high pressure with entrances and necessary exits for the water and air scoop representing the generator, an air compressor for pressurization of the system and devices of control and command for the a automation of the system. The viability of operation of the equipment was demonstrated as also the joined limitations of the archetype / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica
516

Development of a conceptual model for ash dump system using hydraulic and tracer test techniques

October, Adolf Gerswin January 2011 (has links)
Magister Scientiae - MSc / Coal provides for 77% of South Africa’s primary energy needs and is therefore a major resource that supports the socio-economic needs of South African citizens. Power stations are the major consumers of coal in South Africa and produces electricity from burned coal. The burning of coal produces a large volume of ash that is disposed in the form of ash dump systems. The ash dump system is treated with high salinity process water from the power station for dust suppression. The process water contains salts due to evaporation processes from the recirculation of water in the cooling water system. Various studies to evaluate the sustainability of the ash dump system as a sustainable salt sink were therefore conducted. This study aimed to develop a conceptual model for the ash dump system by evaluating the movement of the process water trough the ash dump and the impacts it might have on the underlying weathered dolerite aquifer. This was achieved by evaluating the hydraulic and transport properties of the ash dump system. An initial site conceptual model was first established prior to the application of the hydraulic and transport methods. The initial conceptual model was based on the literature, previous reports and an initial site walk over. Known and tested hydraulic and transport methods were applied n bo.th field and laboratory scale for the saturated part of the ash dump system. The laboratory experiments comprised of column and core experiments. These methods assisted in parameter estimation of hydraulic and transport properties and also assisted in the planning of the field experiments. The field experiments were conducted in the form of slug tests, tracer dilution and natural gradient divergent tracer test experiments. The combined laboratory and field experiments provided statistically significant values that were then used as inputs into the conceptual model. Field experiments were also applied to a surrogate aquifer that represented the underlying shallow weathered dolerite aquifer of the ash dump system. The components of the updated conceptual model identified and investigated include the physical environment, the calculated hydraulic and transport properties.The ash dump can be conceptualized as a 20 to 30 meter high heap of consolidated clay size ash particles built on top of an underlying shallow weathered dolerite aquifer. The ash dup is directly connected to the underlying weathered dolerite aquifer. The saline water within the saturated zone has the ability to move through the ash dump system with hydraulic conductivities ranging between 10-1-10- 2 m/day, with flow velocities of 7-8m/day and effective porosities of 1%-2%. The hydraulic properties of the ash dump are, amongst others, controlled by the ash geology, contact time of the process water with the sh and show a significant reduction in hydraulic conductivity over time, before reaching a steady state. The transport properties are controlled by advection and spreading in available pathways. Results for the surrogate underlying fractured rock aquifer show flow velocities of 31m/day and an effective porosity of 1%.This suggests that the underlying weathered dolerite aquifer is vulnerable to process water contamination from the ash dump system. The study illustrates the importance of a site conceptual model before the application of investigative methods. Hence having a site conceptual model provides an excellent platform for hydraulic and transport estimation. The development of a site conceptual model enhanced the understanding of flow and transport movement of the processed water trough the ash dump, it also assisted as a beneficial tool to enhance ash dump management. / South Africa
517

FUNDAMENTAL STUDY ON UNDULAR AND DISCONTINUOUS HYDRAULIC JUMPS BY MEANS OF ASIMPLIFIED MOMENTUM EQUATION / 簡易型運動量方程式を用いた波状跳水及び不連続跳水に関する基礎的研究

THIN, THWE THWE 23 September 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22756号 / 工博第4755号 / 新制||工||1744(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 細田 尚, 教授 戸田 圭一, 准教授 音田 慎一郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM
518

Impact of Physical Clogging Due to Sedimentation on Soil and Reservoir Hydraulic Performance / 堆砂による物理的目詰まりが土壌と貯水池の水理的性能に及ぼす影響

Elleithy, Dina Mostafa Abdelmonium Hassan 23 March 2021 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第23172号 / 工博第4816号 / 新制||工||1753(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 准教授 竹門 康弘, 准教授 Sameh Kantoush / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
519

Vrtací jednotka / Drilling Unite

Glembek, Jan January 2008 (has links)
The goal of this work is a design of a hydraulic drilling unit and a manipulator for the PSU 9000 machine. The introduction describes the use of underground mining drilling machines and mentions some of the current solutions. The second part contains the design and calculations of individual components. In the final part, the finite-element method is used for calculation of the bearing parts of the construction.
520

Hydraulická drapáková lopata / Hydraulic grab bucket

Vavrla, Petr January 2009 (has links)
In those work am intent on construction hydraulic grab, his two dipper, but largely supporting frame, that is of mostly effortful. Further am suggested and drew up hydraulic perimeter for operating dipper and rotation about perpendicular axes

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