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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.
41

Empirical studies of laminar flow in porous consolidated media

Lehr, Jay H.,1936- January 1962 (has links)
The influence of geologic factors in controlling flow patterns in hydraulic systems is evaluated by hydraulic models which are constructed as a porous consolidated media that simulates the interstitial geometry of consolidated rocks. Colored inks are injected into the flow system and are observed through the transparent sides of the model case. Visual analysis of the flow system, leads to salient conclusions concerning fundamental aspects of complex flow systems. Empirical experiments were conducted on the following aspects: Refraction of flow lines across lithologic interfaces: The law of streamline refraction, as described by King Hubbert, was found to be correct where boundary conditions do not interfere. Continuity of flow around and through highly permeable and impermeable lenses of different lithologies: The flow system around impermeable lenses indicates the nonexistence of stagnant areas where a hydraulic gradient is imposed on a saturated ground water system. Flow net system caused by a single pumping well: Transient changes of individual flow vectors, within the immediate area of influence, were analyzed at the moment pumping began. The absence of a transition phase indicates a rapid adjustment of the flow system to the pumping condition. Flow net system of mutual interference of depression cones caused by pumping multiple wells: This permitted an analysis of the ground water divide. Flow bands divided into flow paths which moved in opposite directions. Effects of emplacing pumping wells in highly permeable media: The increased area of influence of water movement to wells was clearly illustrated. This analysis demonstrates the capture of partially confined flow from great dths. The relation of the shape of artificial recharge pits to infiltration rate: Variations of flow net systems of rectangular and wedge-shaped pits were analyzed. When all other factors were held constant, the shape of the recharge pit was found to have no important effect upon recharge rate. Flow toward an effluent stream: The potential head of ground water beneath the stream was found to increase with depth. The relationship between hydraulic gradient and flow net configuration: The hydraulic gradient was found to have no effect on the flow net of a confined system, but a definite effect upon unconfined flow systems, in as much as it alters the water table which is the upper flow boundary. Flow pattern through tilted and faulted sedimentary structures: The geometric convergence of the aquifer boundaries caused the convergence of flow lines through a brecciated fault zone. A possible genesis of a hydrothermal vein ore was suggested by this flow pattern. Formation of perched water tables: The mechanisms by which saturated ground water mounds can be formed on a low permeability lens was demonstrated. Evidence was found which indicates that perched ground water probably escapes through the perching body as well as around its extremities. Confluence of gravity water and saturated flow: Unsaturated flow arriving at the water table of the saturated ground water body becomes an integral part of that body which acts as a single hydrodynamic system. Artesian ground water systems: A model illustrating the classic artesian aquifer situation was constructed, andflowing and non-flowing artesian wells were studied. A ground water mound was formed in the water table aquifer by water discharging naturally from the artesian aquifer through a fault in the confining layer. Subsidence around a pumping well: Water was pumped from a simulated artesian well, the piezometric surface in the vicinity of the well was lowered and the overburden was observed to subside while compressing the artesian aquifer. Cone of depression formed around single and multiple well systems: The drawdown at any point within the area of influence of a multiple well system was shown to be equal to the sum of the individual drawdowns of each well in the multiple well system, provided recharge and evaporation are neglected. Information resulting from these studies will provide guides for scientific development and exploitation of ground water supplies. Contributions were made that will advance the use of hydraulic models as exploratory tools in scientific hydrology. Further, this work brought into focus the importance of hydraulic models as couinunication media for interpreting cause-effect relationships in highly complex flow systems, of the type that so often are involved in regional problems of water resource development and management.
42

Loss coefficients at straight through manholes

Elgattas, Mohammed Saleh January 1995 (has links)
No description available.
43

Fluid metering using active materials

Sangiah, Dhinesh January 2011 (has links)
No description available.
44

Estudo do comportamento hidráulico e da eficiência na decantação de alta taxa / Not available

Cunha, Francisco Humberto Rodrigues da 06 October 1989 (has links)
Foram desenvolvidos estudos teóricos e experimentais do desempenho e do comportamento hidráulico em decantadores de alta taxa objetivando conhecer melhor a influência de suas características físicas sobre a eficiência na remoção de partículas e estabelecer metodologia adequada para a aplicação de modelos teóricos. Os experimentos foram conduzidos em instalações adaptadas a linha de processo de uma ETA convencional. O modelo teórico e uma simplificação sugerida mostram-se mais consistentes que o de Yao para expressar a influencia da forma da seção dos sedimentadores sobre seu desempenho. Este ocorreu satisfatoriamente ao esperado, mesmo para taxas de trabalho bem superiores as usuais. Quanto as suas dimensões físicas, a largura nao evidenciou influencia sobre a eficiência de remoção de turbidez, confirmando as previsões do modelo teórico proposto e divergindo dos prognósticos do modelo de Yao. Este resultado também revela que a escolha entre formas mais tubulares ou mais largas para os sedimentadores deve ser decidida com base apenas em considerações de ordem prática, tais como os aspectos construtivos, operacionais e econômicos envolvidos nessas opções. / Theoretical and experimental studies concerning high rate settlers performance and hydraulic behavior were conducted to archieve a better understanding about the effects of its physical characteristics over the particle removal efficiency and to establish an appropriate methodology to theoretical model applications. The experimental investigations were performed in a pilot facility adapted to the process line of a conventional water treatment plant. As a result, a theoretical model based on a more extensive concept than the Yao theory was poposed and a methodology for settling analysis specifically related to the high rate settling which reflects the low occurence of flocculation in such cases and corrects the results by the viscosity variation with the temperature. The proposed theoretical model and a suggested simplification were more appropriate than the Yao model to express the influence of the settler section form about its performance. The others physical characteristics of the settlers and the hydraulic flow parameters apparently have been properly accounted by both of the theoretical models so that no additionals restrictions are necessary in this case, unlike the recommended by some authors. The settlers performance has satisfied the requirements, even under overflow rates much higher than the usual ones. Regarding to the physical dimensions, the width of the settlers had not evidencied any influence over the turbidity removal efficiency, as predicted by the proposed theoretical model, indicating that the choice among more tubular or wider settlers section forms should be only based on practical considerations, such as constructive operational and economic aspects.
45

Optimering av säkerhetslager : meddelandehantering i planeringssystemet JDE

Lindström Overgaard, Christina January 2002 (has links)
No description available.
46

RELAP5-3D Thermal Hydraulics Computer Program Analysis Coupled with DAKOTA and STAR-CCM+ Codes

Rodriguez, Oscar 14 March 2013 (has links)
RELAP5-3D has been coupled with both DAKOTA and STAR-CCM+ in order to expand the capability of the thermal-hydraulic code and facilitate complex studies of desired systems. In the first study, RELAP5-3D was coupled with DAKOTA to perform a sensitivity study of the South Texas Project (STP) power plant during steady-state and transient scenarios. The coupled software was validated by analyzing the simulation results with respect of the physical expectations and behavior of the power plant, and thermal-hydraulic parameters which caused greatest sensitivity where identified: inlet core temperature and reactor thermal power. These variables, along with break size and discharge coefficients, were used for further investigation of the sensitivity of the RELAP5-3D LOCA transient simulation under three difference cases: two inch break, six inch break, and guillotine break. Reactor thermal power, core inlet temperature, and break size were identified as producing the greatest sensitivity; therefore, future research would include uncertainty quantification for these parameters. In the second study, a small scale experimental facility, designed to study the thermal hydraulic phenomena of the Reactor Cavity Cooling System (RCCS) for a Very High Temperature Reactor (VHTR), was used as a model to test the capabilities of coupling Star-CCM+ and RELAP5-3D. This chapter discusses the capabilities and limitations of the STAR-CCM+/RELAP5-3D coupling, and a simulation, on the RCCS facility, was performed using STAR-CCM+ to study the flow patterns where expected complex flow phenomena occur and RELAP5-3D for the complete system. The code showed inability to perform flow coupling simulations and it is unable, at this time, to handle closed loop systems. The thermal coupling simulation was successful and showed congruent qualitative results to physical expectations. The locations of large fluid vortices were located specifically in the pipes closest to the inlet of the bottom manifold. In conclusion, simulations using coupled codes were presented which greatly improved the capabilities of RELAP5-3D stand-alone and computational time required to perform complex thermal-hydraulic studies. These improvements show greatly benefit for industrial applications in order to perform large scale thermal-hydraulic systems studies with greater accuracy while minimizing simulation time.
47

Optimering av säkerhetslager : meddelandehantering i planeringssystemet JDE

Lindström Overgaard, Christina January 2002 (has links)
No description available.
48

The Design and Qualification of a Hydraulic Hardware-in-the-Loop Simulator

Driscoll, Scott Crawford 20 May 2005 (has links)
The goal of this work was to design and evaluate a hydraulic Hardware-in-the-Loop (HIL) simulation system based around electric and hydraulic motors. The idea behind HIL simulation is to install real hardware within a physically emulated environment, so that genuine performance can be assessed without the expense of final assembly testing. In this case, coupled electric and hydraulic motors were used to create the physical environment emulation by imparting flows and pressures on test hardware. Typically, servo-valves are used for this type of hydraulic emulation, and one of the main purposes of this work was to compare the effectiveness of using motors instead of the somewhat standard servo-valve. Towards this end, a case study involving a Sauer Danfoss proportional valve and emulation of a John Deere backhoe cylinder was undertaken. The design of speed and pressure controllers used in this emulation is presented, and results are compared to data from a real John Deere backhoe and proportional valve. While motors have a substantially lower bandwidth than servo-valves due to their inertia, they have the ability to control pressure at zero and near-zero flows, which is fundamentally impossible for valves. The limitations and unique capabilities of motors are discussed with respect to characteristics of real hydraulic systems.
49

Effect of heating upon mass flow rate through ports of a manifold

Safar, Lewis Anthony 05 1900 (has links)
No description available.
50

Characterizing the distribution of hydraulic properties in the Glacial Lake Agassiz peatlands using a three-dimensional numerical model and regularized inversion /

Rhoades, Joshua L., January 2009 (has links)
Thesis (M.S.) in Earth Sciences--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 95-105).

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