Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 31 for “"gas bubble"”.
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Gas assisted injection moulding: Experiment and simulation. Industrial machine experimental studies of the effect of process variables on gas bubble formation, and with simulation based upon a pseudo-concentration method.
The gas assisted injection moulding process is an important extension to conventional injection moulding. Gas assist can be applied in a number of ways, but here the penetration of a gas bubble through the polymer melt is of interest. A 3D fi nite element implementation of a pseudo concentration …
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Investigation of enhanced aluminum casings for underwater explosives and development of spectroscopic techniques for measuring temperature in environments relevant to underwater ordnance
… without cavities in terms of enhanced radial bubble growth. It was also shown that cavities with sharp angles at the apex performed better at increasing the bubble volume as opposed to linear cavities with rounded geometries. The theoretical work analyzed the enhancement of aluminum spheres …
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Empirical investigation of underwater blast
… that a submerged detonation creates a pulsating gas bubble. Such a bubble is absent in an explosion in air. This thesis is focused on underwater detonations. It is well known that about half of the energy of an underwater detonation is transferred to the gas bubble (see Figure A), therefore it is …
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LARGE-EDDY SIMULATION OF DEEP-WATER HYDROCARBON PLUME DYNAMICS
… hydrocarbon plume is strongly affected by the gas dissolution and hydration process that weakens the bubble-induced buoyancy for driving the plume. In this study, a new modeling strategy is developed to efficiently incorporate the gas dissolution and hydration effects into a fast …
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Fission Gas Transport and Its Interaction With Irradiation Induced Defects in Lanthanum Doped Ceria
… distributions of dislocation loops, voids and gas bubble structures created by irradiation. More importantly, this systematic experimental work has provided key insights into the understanding of the mechanisms of defect evolution in the materials investigated. A model including both defect …
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The effect of gas on multi-stage mixed-flow centrifugal pumps
… is a mixture of liquids (oil and water) and gas, and is often maintained by using a pump placed in the well to ensure a continuous flow to the surface. Electrical Submersible Pumps consist of stacked centrifugal pump stages, each comprising a bladed impeller (rotating part) and diffuser …
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CPFD Modeling of a Novel Internally Circulating Bubbling Fluidized Bed for Chemical Looping Combustion
… to concentrate carbon dioxide in the flue gas stream. Oxygen is supplied through cyclic oxidation and reduction of a solid metal oxide between an air reactor and fuel reactor to prevent the direct contact of fuel and air. CanmetENERGY-Ottawa, in collaboration with Hatch Ltd., is designing a …
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Behavior of Light in a Photobioreactor and Design of Light Guides
… light with all the factors like growth medium, gas bubble flumes, biomass concentration, and the light path length in the photobioreactor system. These experiments are used to determine the light penetration in to a photobioreactor system.</p>
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Underwater Pipeline Leakage Detection Using Vision Based Techniques: Semi-AUV (SAUV) Approach
… The SAUV was used for automatic underwater gas pipeline tracking and leakage detection. the leakages in the pipeline using Computer Vision. The SAUV was designed to operate both manually and automatically in underwater conditions. The proposed SAUV has 6 thrusters to achieve 4 degrees of …
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Two phase problems and two phase flow
… is used to investigate the circulation in a gas-bubble agitation system of a cylindrical vessel for the case of an orifice located at the centre of the base. The two-phase (liquid/gas) region is assumed to be confined to a cone-shaped region and is investigated using Wallis' Drift Flux Model. …
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The harmonic excitation of a cylindrical bubble pinned to a plane surface: flow field and oscillation dynamics
… to describe the response of a hemicylindrical gas bubble pinned to rigid substrate to an imposed oscillatory far field pressure, and subsequently describe the resulting steady flow that results in the fluid in the exterior of such a bubble. We first derive an analytical expression for the …
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Molecular dynamic simulation of xenon bubble re-solution in uranium dioxide
… comprehensive study of two mechanisms of fission gas bubble re-solution in UO2 by molecular dynamics (MD) simulations: homogeneous re-solution and heterogeneous re-solution. For the homogeneous mechanism, a hybrid approach is employed whereby Monte Carlo (MC) simulations are used to obtain the …
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Experimental investigation of local properties in two-phase fluid-flow hydrodynamics
Local, time-averaged measurements of gas void fraction, gas velocity, gas bubble diameter, and bubble passage frequency were made in a concurrent-flow, vertical rectangular channel (15.0 x 1.25 cm) having an aspect ratio of 12:1. Twenty (20) flows were analyzed with superficial gas and liquid …
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Modelling and simulation of all-vanadium redox flow batteries
… model for reactions involving vanadium species. Gas evolving reactions are then incorporated into the modelling frame work. Bubble formation as a result of evolution at the negative/positive electrode is included in the model, taking into account the attendant reduction in the liquid volume and …
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A New Dynamic Fluid Flow Method for Studying the Phase Changes of the Light/Heavy Crude Oil-Solvent Systems
… as long as the outlet pressure was above the bubble-point pressure of the light crude oil‒CO2 system. However, the pressure gradient was suddenly increased once the outlet pressure was below the bubble-point pressure because the light crude oil‒CO2 system changed from one liquid phase into …
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A fundamental approach to predicting mass transfer coefficients in bubble column reactors
A bubble column reactor is a vertical cylindrical vessel used for gas-liquid reactions. Bubble Columns have several applications in industry due to certain obvious advantages such as high gas-liquid interfacial area, high heat and mass transfer rates, low maintenance requirements and operating …
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Bubble Induced Heat Transfer in Two-Phase Systems
… A model of heat transfer from a surface to a gas fluidized bed based on the extended theory has been developed. Aggregative gas fluidized beds and bubbling gas-liquid systems can be unified from the point of view of heat transfer by defining a general two-phase system consisting of a discrete …
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The undrained behavior of saturated, dilatant silts
… to investigate whether cavitation and dissolved gases exiting solution from soil pore water are the cause of the erratic undrained behavior often observed in triaxial tests on saturated, dilatant silts. The literature indicates that ground water contains various amounts of dissolved gases and …
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Analysis of diagnostic testing of sustained casing pressure in wells
… to the loss of well’s external integrity causing gas inflow from a high-pressure formation into the well’s annulus. Then, the gas migrates upward through a leaking cement sheath, percolates through the mud column and accumulates above the liquid level inside the gas cap. The study identified two …
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Atomistic Simulation Of Plasma Interaction With Plasma Facing Components In Fusion Reactors
… prior to deuterium cluster formation, and gas bubbles were observed. The formation of gas bubbles were caused by the near surface deuterium super-saturation region and the subsequent plastic deformation induced by the local high gas pressure.</p> <p>Tungsten irradiated by carbon and …
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