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 26 for “"surface porosity"”.
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On the Use of Surface Porosity to Reduce Wake-Stator Interaction Noise
… was designed to assess the potential of Passive Porosity Technology as a mechanism for alleviating interaction effects and radiated noise by reducing the fluctuating forces acting on the vane surfaces. The study involved a typical high bypass fan stator airfoil immersed in a subsonic free field …
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A study of surface porosity formation in deposits sprayed onto flat substrates by the Uniform Droplet Spray process
… state of spray forming processes, deposit surfaces formed on a substrate contain porosity. This surface porosity requires secondary operations to be removed. The added expense of these operations prevents the full industrialization of the spray forming process. Thus, a basic understanding …
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Dam dimensions and surface porosity affect the water storage capacity of Beaver dam analogs compared to natural Beaver dams
… effectiveness. Dam height, thickness, length and porosity were the predictor variables. While BDA water travel times were significantly longer than control sites, natural beaver sites exhibited significantly higher HRT than BDA sites. Beaver dams were also significantly thicker and longer than …
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Polyacrylonitrile hollow fibre membranes for gas separation
… showed that the calculated pore radius on the surface of the fibre was in the range of 4- 32 nm. After coating with silicone rubber, the membranes showed very poor gas permeability and selectivity. Since PAN has a low intrinsic gas permeability, the low permeability observed is ascribed to a …
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Production and characterisation of poly(vinyl chloride) (PVC) hollow fibre membranes for gas separation applications
… of the results.Scanning electron microscopy surface images revealed defects in the membranes surface (tearing). However, the Knudsen selectivity obtained for the uncoated membranes and the significant decline in the gas permeation through the membrane after coating cycles suggests that the …
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Processing-structure-property relationships of surface porous polymers for orthopaedic applications
… clinical success. In this dissertation, a novel surface porous structure has been created, where limiting the porosity to the surface maintains adequate mechanical properties for load bearing applications while providing a surface for improved osseointegration. Careful control of the processing …
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The grinding of polyethylene powders for use in rotational moulding
… in size by the removal of shavings from the surface of the pellet as it moves across the narrowing gap in the grinding zone. Features of the grinding zone such as the length, angle of rotating plate, number and angle of rotating teeth were found to have a great influence on the throughput …
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Separate effects of surface roughness, wettability and porosity on boiling heat transfer and critical heat flux and optimization of boiling surfaces
The separate effects of surface wettability, porosity, and roughness on critical heat flux (CHF) and heat transfer coefficient (HTC) were examined using carefully-engineered surfaces. All test surfaces were prepared on nanosmooth indium tin oxide - sapphire heaters and tested in a pool boiling …
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Investigation of Plasma Electrolytic Oxidation (PEO) Coated Bores in Internal Combustion Engines
… along the piston ring and cylinder bore sliding surface. For PEO coatings, wear is a limiting factor and this study aims at understanding the main influencing factors for wear on PEO in cylinder bores. Through fired-engine dynamometer testing, it was determined that large piston-to-bore clearance …
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Optimization Of Wind Fence Enclosures For Infrasonic Wind Noise Reduction
… hose arrays. The effects of varying the fence's porosity, modifying its top condition and bottom gap, doubling the height and diameter, and adding a secondary wind barrier were investigated. A simple mathematical model which estimates the wind noise measured at the center of the enclosure was …
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Elucidation of Drug Release Mechanisms in PLGA Microspheres
… Mg(OH)2 as a stabilizing excipient affected the surface porosity of the microspheres, which in turn affected the burst of drug during early release. We were further able to modulate release using size---following the burst, smaller spheres released faster than their larger counterparts, due to …
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Studies investigating the preparation of solid core drug delivery systems for oral delivery of y-globulin via supercritical fluid processing technology
… for immobilization of these molecules on a solid surface to improve and maintain their stability, followed by the enteric coating to achieve targeted/sustained release. Furthermore, supercritical fluid technology (SCFT) as a processing technique may be explored to ensure that the integrity of …
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Optimising Mass Transfer in Synthetic Porous Materials
… through larger pores and increase the specific surface area via smaller branching pores. Optimising these porous structures for enhanced transfer performance has attracted considerable effort. In this regard, Murray’s law has been adapted to design and construct synthetic porous materials, …
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Printable and Machine Intelligent 0D/2D Materials Gas Sensor Arrays
… I determine key parameters affecting aerogels’ surface porosity, including the ink’s crosslinking degree, nozzle diameter, shear stress during printing, and freeze-drying conditions. I construct multiplexed filament-structured aerogel GSAs with various controllable morphologies and chemical …
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Earth’s oceanic oxygen history from Phanerozoic to Pleistocene glacial cycles: insights from the carbonate iodine-to-calcium proxy
… <p>4) Direct comparison of benthic foraminiferal surface porosity and I/Ca proxies.</p> <p>Benthic foraminiferal surface porosity (the mean percentage of surface area covered by pores; higher porosity: lower oxygenation) and I/Ca (higher I/Ca: higher oxygenation) are both promising …
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Surface Patterned Ceramics Via Breath Figures Method With Potential Application As Implant Coatings
Surface porous silicon based ceramics are a class of materials with excellent mechanical, physical and chemical properties and for this reason they are widely used in different fields of application. The resultant properties of these material are due principally to the combination of the chemical …
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Projeto e fabricação de um reator para tratamento superficial de implantes por oxidação eletrolítica a plasma
… adverse environments. Accordingly, appropriate surface modification is required for titanium based alloys, improving the surface properties and their bioactivity. There is a wide spectrum of surface modification techniques available, such as physical vapor deposition, chemical vapor deposition, …
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Hybrid Organic/Inorganic Flexible Structures: Low Temperature Deposition of Silver Conductive Tracks on Flexible Substrates
… or a spray gun. Relatively uniform Ag track surface geometries were obtained. Contact angle measurements (<17°) showed good adhesion of the Ag ink on the PEN substrate. Curing of the Ag patterns was performed via radiation-conduction-convection heating at temperatures as low as 150°C …
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Strategies for Improving the Bacterial Biodegradation of PET
… I. sakaiensis culture supplemented by QSM. The surfaces of FSC-treated PET exhibited notable roughness compared to untreated PET, coupled with an increased surface porosity. These structural modifications validate the findings derived from FTIR spectroscopy, fortifying the substantial strides …
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Development of Innovative Ultra-Filtration Fibre Technologies for Waste-Water Treatment in Membrane Bio-Reactors (MBR)
… will provide a route towards optimising membrane surface porosity, translating into potential improvements in fibre permeability and anti-fouling propensity. Three different experimental approaches were implemented to assess the impact of fibre composition on membrane performance. These include …
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