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 40 for “"Bulk diffusion"”.
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Evaluation of Chloride Diffusion in Concrete Using Bulk Diffusion Test and Scanning Electron Microscopy
… environment for 6 months. The standardized Bulk Diffusion, BD, test according to ATSM C1556 was conducted to obtain concrete powder samples which underwent chemical analysis according to FDOT criteria, FM5-516. The research project team experienced the significant time, resources, and labor …
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In situ investigation of the dealloying process using environmental transmission electron microscopy
… process is thought to proceed by either surface diffusion or bulk diffusion. While the process has been studied extensively in the past, it was primarily on model systems such as single crystal gold-based alloys which are governed by the surface diffusion mechanism. This study seeks to provide …
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Diffusion of Prodan on Self -Assembled Monolayers and Grafted Polymer Layers
Two grafted polymer layers were synthesized, for diffusion studies, with surface-initiated polymerization (SIP). The results suggest that there is very little bulk translational diffusion in first layer, poly (N-isopropylacrylamide) (PNIPAM). Rather, fluorescence recovery is thought to be due to …
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Hydrogen Transport in and Through Niobium
… performed in order to understand the roles of bulk diffusion and surface processes in hydrogen transport in and through niobium. Bulk hydrogen and deuterium diffusivities and permeabilities were measured at high temperatures (700 - 1400 K) using diffusion controlled permeation methods. At lower …
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Fibre cement boards as permanent formwork for reinforced concrete elements
… and poor-quality concrete. Durability index, bulk diffusion, and modified interface shear bond tests were conducted. The modified shear bond test demonstrated that a bond with sufficient strength could be attained but further research is required to determine whether the bond is capable of …
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Surfactant instabilities on thin films
… which demonstrates the critical significance of bulk diffusion on the spreding behavior. Finally, we present a numerical implementation of a mathematical model which is capable of reproducing the experimentally observed trends.
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Estimation of evaporation of previously condensed hydrocarbons in a tunnel burn experiment
… evaporation/sublimation was then estimated as bulk diffusion into the tunnel air. The results provide a method to compute the evaporation rate. Good agreement is shown for the predicted temperatures compared to the measured values, although a wide variation is shown in the experimental results. …
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Isotope effect for diffusion of tin in beta-titanium
The isotope effect for diffusion of in Ti has been measured at five temperatures in the bcc G-phase. Separation of the Sn isotopes was effected by 3-spectroscopy on electroplated sources. The effect is small and highly temperature-dependent, varying from 0.18 ± 0.03 at 9720 C to 0.37 ± 0.03 at …
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Electrochemomechanics in Mixed Ionic Electronic Conductors and solid oxide cells
… the effect of oxygen surface exchange and the bulk diffusion of defects on the performance of solid oxide cell. In the fourth chapter, the transport of ionic defects is studied under spatially varying oxygen surface exchange in solid oxide cells due to the presence of metal current collector. …
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Interaction of germanium with platinum group metals in lateral diffusion couples
… of physics and materials. The study of lateral diffusion couples is particularly well suited for dealing with the above concerns. This thesis looks at metal-germanium systems of the Platinum Group Metals (PG Ms). It is of particular relevance to study possible applications of PG Ms in South …
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New mechanisms for defect engineering in titanium dioxide
… engineering in titanium dioxide based on surface-bulk coupling, photo-stimulation, and interaction of charged defects at the surface. While titanium dioxide is utilized as a model, the principles observed for titanium dioxide will translate well into other metal oxide semiconductors. Through …
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Properties and sensor performance of zinc oxide thin films
… temperatures of these thin film sensors, bulk diffusion cannot be discounted. The oxygen partial pressure dependence of the sensor resistance and its corresponding activation energy were related to defect process controlling the reduction/oxidation behavior of the ZnO.
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Deep understanding of degradation in lithium ion batteries through experimental and first-principles study
… coating material via faster Li diffusion, facile intercalation, and less mechanical damage of coating. Paper II discovered an unexpected metal dissolution that ultrathin CeO<sub>2</sub> coating intensifies the Mn dissolution of LMO and it was confirmed in several ways, including …
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Hydrogen transport in and through niobium
… performed in order to understand the roles of bulk diffusion and surface processes in hydrogen transport in and through niobium. Bulk hydrogen and deuterium diffusivities and permeabilities were measured at high temperatures (700 -1400 K) using diffusion controlled permeation methods. At lower …
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Low-Temperature Densification of Lead Zirconate Titanate With Vanadium Pentoxide Additions
… by the enhancement of grain-boundary and/or bulk diffusion which are enhanced by the presence of a high defect concentration and reactive liquid phase at the grain contact areas.
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Investigating repair mortars containing superabsorbent polymers as a method of internal curing to improve concrete patch repair performance
… relaxation, elastic modulus, carbonation, bulk diffusion and free and restrained shrinkage. The results of this research indicate d that the SAP's had a greater influence on samples with a higher w/b ratio. The results also suggested that an increase in SAP content resulted in improved …
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Fundamental Importance of Fillers, Cure Condition, and Crosslink Density on Model Epoxy Properties
… silica did not significantly affect moisture diffusion properties. Next, a linear dilatometer was used to investigate the effects of cure conditions, mold types, and the presence of filler in the model epoxy. These studies revealed that there was substantial shrinkage in the cured epoxy on …
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Mechanistic Modeling of Nuclear Waste Form Leaching by Aqueous Solutions
… solution. A basic distinction is made among bulk, surface, and leachant species, as well as between major (i.e., network formers) and minor (i.e., network modifiers) constituents of the solid structure. Major constituents exhibit no mobility within the solid bulk. Minor constituents may …
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An off-lattice kinetic Monte Carlo method for the investigation of grain boundary kinetic processes
… validating these methods in the study of vacancy diffusion, we implemented our off-lattice Kc method to study the kinetic behavior of the [Sigma]5 (210) grain boundary (GB) in copper. We found that the activation energy associated with intrinsic diffusion at this GB is between the activation …
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Evaluation of surface treatments for RC structures failing to meet South African durability index requirements
… and custom tests differing from the standard bulk diffusion test were used to evaluate performance. Chloride resistance was improved due to the pure silane however service life improvements could not be quantified. Unexpected failures occurred during the laboratory investigation rendering a …
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