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Articles 1 - 19 of 19
Full-Text Articles in Engineering
Adsorption And Diffusion Of Gases In Nano-Porous Materials, Nethika Sahani Suraweera
Adsorption And Diffusion Of Gases In Nano-Porous Materials, Nethika Sahani Suraweera
Doctoral Dissertations
In this work, a systematic computational study directed toward developing a molecular-level understanding of gas adsorption and diffusion characteristics in nano-porous materials is presented. Two different types of porous adsorbents were studied, one crystalline and the other amorphous. Physisorption and diffusion of hydrogen in ten iso-reticular metal-organic frameworks (IRMOFs) were investigated. A set of nine adsorbents taken from a class of novel, amorphous nano-porous materials composed of spherosilicate building blocks and isolated metal sites was also studied, with attention paid to the adsorptive and diffusive behavior of hydrogen, methane, carbon dioxide and their binary mixtures. Both classes of materials were …
Nonlinear Adaptive Diffusion Models For Image Denoising, Ajay Kumar Mandava
Nonlinear Adaptive Diffusion Models For Image Denoising, Ajay Kumar Mandava
UNLV Theses, Dissertations, Professional Papers, and Capstones
Most of digital image applications demand on high image quality. Unfortunately, images often are degraded by noise during the formation, transmission, and recording processes. Hence, image denoising is an essential processing step preceding visual and automated analyses. Image denoising methods can reduce image contrast, create block or ring artifacts in the process of denoising. In this dissertation, we develop high performance non-linear diffusion based image denoising methods, capable to preserve edges and maintain high visual quality. This is attained by different approaches: First, a nonlinear diffusion is presented with robust M-estimators as diffusivity functions. Secondly, the knowledge of textons derived …
Non-Mass Transfer Limited Crystal Growth, Ryan J. Smyth, Caitlin Schram, Stephen P. Beaudoin
Non-Mass Transfer Limited Crystal Growth, Ryan J. Smyth, Caitlin Schram, Stephen P. Beaudoin
The Summer Undergraduate Research Fellowship (SURF) Symposium
There are many different active pharmaceutical ingredients (APIs) that have been discovered in research labs all around the world that can be used to treat and cure patients with a variety of different ailments. The challenge with these APIs in treatments is that they are not soluble in water, thus they low absorption into the blood stream (bio-availability). The key to making these APIs more bio-available is to understand how they grow as crystals and drop out of the aqueous solutions. One of the ways these APIs were made more bio-available is to render them amorphous and suspend them in …
Kinetic Monte Carlo Simulations, Jingyuan Liang, R. Edwin García, Ding-Wen (Tony) Chung, David Ely
Kinetic Monte Carlo Simulations, Jingyuan Liang, R. Edwin García, Ding-Wen (Tony) Chung, David Ely
The Summer Undergraduate Research Fellowship (SURF) Symposium
Kinetic Monte Carlo (kMC) is a set of scientific libraries designed to deploy kMC simulations intended to simulate the time evolution of some processes occurring in nature. kMC is currently allows the user to intuitively generate single component crystal lattices to simulate, post process, and visualize the kinetic Monte Carlo-based atomistic evolution of materials. kMC provides an interface to the Stochastic Parallel PARticle Kinetic Simulator (SPPARKS) [1] and is specifically designed to simulate individual atomic deposition (condensation) and dissolution (evaporation) events, while simultaneously tracking the surface and bulk crystallographic anisotropic diffusion. The main goal of this project is to create …
Modeling Target Disinfection By-Product Dynamics In Indoor Swimming Pools, Barnard S. Mondal, Cary Troy, Mehrnaz Afifi, Shih-Chi Weng, Ernest R. Blatchley Iii
Modeling Target Disinfection By-Product Dynamics In Indoor Swimming Pools, Barnard S. Mondal, Cary Troy, Mehrnaz Afifi, Shih-Chi Weng, Ernest R. Blatchley Iii
The Summer Undergraduate Research Fellowship (SURF) Symposium
Chlorination is the primary disinfection method for swimming pools in the United States; however, chlorine also reacts with pollutants (e.g., sweat, urine and anthropogenic compounds) to form disinfection by-products (DBPs). Some DBPs are asthma causing (e.g. nitrogen-trichloride) and even carcinogens (e.g., trihalomethanes and nitrosamines). Consequently, exposure to DBPs poses health risks to patrons and staff in pool environments. Furthermore, volatilization of DBPs is enhanced by bather activity, but the relationship between activity and volatilization has yet been quantified such that the dynamic behavior of DBPs can be predicted. Therefore, the objective of this research is to …
Is Dna A Good Model Polymer?, Douglas R. Tree, Abhiram Muralidhar, Patrick S. Doyle, Kevin D. Dorfman
Is Dna A Good Model Polymer?, Douglas R. Tree, Abhiram Muralidhar, Patrick S. Doyle, Kevin D. Dorfman
Faculty Publications
The details surrounding the crossover from wormlike-specific to universal polymeric behavior has been the subject of debate and confusion even for the simple case of a dilute, unconfined wormlike chain. We have directly computed the polymer size, form factor, free energy, and Kirkwood diffusivity for unconfined wormlike chains as a function of molecular weight, focusing on persistence lengths and effective widths that represent single-stranded and double-stranded DNA in a high ionic strength buffer. To do so, we use a chain-growth Monte Carlo algorithm, the pruned-enriched Rosenbluth method (PERM), which allows us to estimate equilibrium and near-equilibrium dynamic properties of wormlike …
Vapor Distribution Above An Evaporating Sessile Drop, Peter Kelly-Zion, Christopher J. Pursell, N Hasbamrer, B Cardozo, K Gaughan, Kevin Nickels
Vapor Distribution Above An Evaporating Sessile Drop, Peter Kelly-Zion, Christopher J. Pursell, N Hasbamrer, B Cardozo, K Gaughan, Kevin Nickels
Engineering Faculty Research
An experimental technique was developed that uses infrared tomography to measure the three-dimensional vapor distribution above an evaporating sessile drop. The technique was applied to measure the vapor distributions above evaporating drops of hexane and 3-methylpentane (3MP) at room temperature and pressure. The molecular masses of these two species are heavier than air and the vapor from the evaporating drop forms a flat, disk-shaped cloud. A Fourier transform infrared spectrometer (FTIR) was used to measure the spectral absorbance along a set of paths passing through the vapor cloud. From a set of path-averaged absorbance measurements, a two-dimensional spatial concentration distribution …
Correlation For The Convective And Diffusive Evaporation Of A Sessile Drop, Peter Kelly-Zion, J. Batra, Christopher J. Pursell
Correlation For The Convective And Diffusive Evaporation Of A Sessile Drop, Peter Kelly-Zion, J. Batra, Christopher J. Pursell
Engineering Faculty Research
A simple correlation is developed to compute the evaporation rates of sessile drops and small puddles which are evaporating under the influences of both diffusion and natural convection of the vapor-air mixture surrounding the drop. The correlation is based on experiments conducted with eight hydrocarbons, which provide a factor of 16.6 variation in volatility as indicated by the equilibrium vapor pressures, a factor of 3.6 variation in molecular mass, and a factor of 2.2 variation in mass diffusivity, and thus the correlation is applicable for liquids having a broad range of properties. The correlation predicts the evaporation rates to within …
The Effect Of Processing Parameters On Barrier Properties Of Polymers, Russell Louis Hallman Jr.
The Effect Of Processing Parameters On Barrier Properties Of Polymers, Russell Louis Hallman Jr.
Doctoral Dissertations
The intent of this work was to learn if polyethylene could be made with predictable water transfer rates by control of the microstructure. A series of films were formed from three different polyethylenes with a range crystallinities using melt pressing, a controlled cooling rate, and subsequent heat treatments. The samples were tested on a novel device called the polymer characterization device that measures the water transfer flux as a function of temperature. The samples’ morphology was examined using differential gradient column, differential scanning calorimetry, Fourier transform infrared microscopy, wide-angle X-ray diffractions, small-angle X-ray scattering, and small angle light scattering, and …
Novel Ceria-Zirconia-Yttria Mesostructures: Synthesis, Characterization, Diffusional Studies And The Effects Of Morphology On Their Properties, Alma Cordova Morales
Novel Ceria-Zirconia-Yttria Mesostructures: Synthesis, Characterization, Diffusional Studies And The Effects Of Morphology On Their Properties, Alma Cordova Morales
All Dissertations
Ceria-zirconia-yttria (CZY) mixed oxides are used as catalyst supports for three-way catalysts for automotive exhaust emission control and in solid oxide fuel cells. By improving the morphology of CZY mesopores it is possible to reduce the sintering of supported noble metals and enhance overall catalyst lifetime and performance. However, limited studies have been published on the synthetic control of the morphology of CZY materials and the effects that CZY pore geometry has on catalyst operation.
To create optimized CZY catalyst supports, novel mesoporous CZY oxides were synthesized via classical sol-gel and evaporation induced self-assembly (EISA) methods, obtaining mesostructures that exhibited …
In-Field Jc Improvement By Oxygen-Free Pyrene Gas Diffusion Into Highly Dense Mgb2 Superconductor, Minoru Maeda, Jung Ho Kim, Y Zhao, Yoon-Uk Heo, K Takase, Y Kubota, C Moriyoshi, F Yoshida, Y Kuroiwa, S X. Dou
In-Field Jc Improvement By Oxygen-Free Pyrene Gas Diffusion Into Highly Dense Mgb2 Superconductor, Minoru Maeda, Jung Ho Kim, Y Zhao, Yoon-Uk Heo, K Takase, Y Kubota, C Moriyoshi, F Yoshida, Y Kuroiwa, S X. Dou
Shi Xue Dou
Oxygen-free pyrene gas as a carbon (C) dopant was delinked and incorporated into highly dense MgB2 structure via a gas phase diffusion method. The technique offers the advantages that molecular C is homogeneously distributed into MgB2 and substituted at the boron sites without any severe deterioration of grain connectivity. The C substitution causes a significant shrinkage of the a-lattice parameter and an increase in the lattice strain, resulting in high disorder. The introduction of structural disorder as a result of C doping leads to a considerable enhancement of the in-field critical current density (Jc) and upper critical field.
A Microfluidic Platform To Quantify Spatio-Temporal Diffusion Of Chemo-Gradients Within 3d Scaffolds: Applications In Axonal Biology, Michael A. Sawonik
A Microfluidic Platform To Quantify Spatio-Temporal Diffusion Of Chemo-Gradients Within 3d Scaffolds: Applications In Axonal Biology, Michael A. Sawonik
ETD Archive
Axonal outgrowth and guidance play an important role in wiring the developing and regenerating nervous system. The critical role of biomolecular gradients in facilitating this axonal sensitivity and directionality along specific trajectories needs to be elucidated for designing effective therapeutic treatments under injury or disease conditions. However, previous in vitro approaches based on micropipette assay or gel-turning assay proved to be unsuitable or inefficient for precise generation and quantification of diffusive gradients. In this study, we utilized a microfluidic device to generate and quantify physiologically-relevant biomolecular gradients in a simple and reliable manner. Using a combination of computational and experimental …
Espi Filtering Method Based On Anisotropic Coherence Diffusion And Perona-Malik Diffusion, Zhitao Xiao, Zhenbei Xu, Fang Zhang, Lei Geng, Jun Wu, Quan Yuan, Jiangtao Xi
Espi Filtering Method Based On Anisotropic Coherence Diffusion And Perona-Malik Diffusion, Zhitao Xiao, Zhenbei Xu, Fang Zhang, Lei Geng, Jun Wu, Quan Yuan, Jiangtao Xi
Faculty of Engineering and Information Sciences - Papers: Part A
Noise reduction is one of the most important concerns in electronic speckle pattern interferometry (ESPI). According to partial differential equation (PDE) filtering theory, we present an anisotropic PDE noise- reduction model based on fringe structure information for interferometric fringe patterns. This model is based on coherence diffusion and Perona-Malik (P-M) diffusion. The former can protect the structure information of fringe pattern, while the latter can effectively filter off the noise inside the fringes. The proposed model generated by the two diffusion methods helps to obtain good effects of denoising and fidelity. ESPI fringes and the phase pattern are tested. Experimental …
Interdiffusion And Impurity Diffusion In Magnesium Solid Solutions, Catherine Kammerer
Interdiffusion And Impurity Diffusion In Magnesium Solid Solutions, Catherine Kammerer
Electronic Theses and Dissertations
Magnesium, being lightweight, offers potential to be developed into extensive structural applications. The transportation segment has particular interest in Mg and Mg alloy for applications where reduced vehicle weight is proportional to increased fuel efficiency. Aluminum and zinc are two of the most common alloying elements in commercial Mg alloys. They improve the physical properties of Mg through solid solution strengthening and precipitation hardening. Diffusion plays a key role in the kinetics of and microstructural development during solidification and heat treatment. However, there is limited diffusion data available for Mg and Mg alloys. In particular, because Al is monoisotopic, tracer …
Interdiffusion Reaction Between Uranium-Zirconium And Iron, Young Joo Park
Interdiffusion Reaction Between Uranium-Zirconium And Iron, Young Joo Park
Electronic Theses and Dissertations
U-Zr metallic fuels cladded in Fe-alloys are being considered for application in an advanced Sodium-Cooled Fast Reactor (SFR) that can recycle the U-Zr fuels and minimize the long-lived actinide waste. To understand the complex fuel-cladding chemical interaction of the U-Zr metallic fuel with Fe-alloys, a systematic multicomponent diffusion study was carried out using solid-to-solid diffusion couples. The U-10 wt.% Zr vs. pure Fe diffusion couples were assembled and annealed at temperatures, 630, 650 and 680°C for 96 hours. Development of microstructure, phase constituents, and compositions developed during the thermal anneals were examined by scanning electron microscopy, transmission electron microscopy and …
Effect Of Exhaust Gas Recirculation And Combustible Oxygen Mass Fraction On Emission Index Of Nox For Counterflow Methane/Air Diffusion Flames, Mugdha S. Sane
Effect Of Exhaust Gas Recirculation And Combustible Oxygen Mass Fraction On Emission Index Of Nox For Counterflow Methane/Air Diffusion Flames, Mugdha S. Sane
Open Access Theses
Exhaust gas recirculation has been proven to be an effective method of reducing emissions of oxides of nitrogen (NOx) from internal combustion engines. The present study validates this effect through flame simulations using detailed chemistry. Counterflow methane/air diffusion flames were simulated in one dimension in physical space using GRI-Mech 3.0 detailed chemistry mechanism, thermal, and transport data. The influence of Exhaust Gas Recirculation (EGR) on the flame structure and NOx emissions was studied by selecting higher than ambient inlet temperature and by varying the composition of the oxidizer stream. The Combustible Oxygen Mass Fraction (COMF), which represents the fraction of …
On The Curve Diffusion Flow Of Closed Plane Curves, Glen Wheeler
On The Curve Diffusion Flow Of Closed Plane Curves, Glen Wheeler
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, we consider the steepest descent H−1-gradient flow of the length functional for immersed plane curves, known as the curve diffusion flow. It is known that under this flow there exist both initially immersed curves that develop at least one singularity in finite time and initially embedded curves that self-intersect in finite time. We prove that under the flow closed curves with initial data close to a round circle in the sense of normalised L2 oscillation of curvature exist for all time and converge exponentially fast to a round circle. This implies that for a sufficiently large ‘waiting …
A Novel Method Of Embedding Additional Information Into Tensor Diffusion Filtering As An Application For Multi-Modal Reconstruction In Et, D Kazantsev, Sebastien Ourselin, Brian F. Hutton, W. R B. Lionheart, Simon Arridge
A Novel Method Of Embedding Additional Information Into Tensor Diffusion Filtering As An Application For Multi-Modal Reconstruction In Et, D Kazantsev, Sebastien Ourselin, Brian F. Hutton, W. R B. Lionheart, Simon Arridge
Faculty of Engineering and Information Sciences - Papers: Part A
The fast development of hybrid imaging modalities in tomography, such as SPECT (single photon emission computed tomography)/CT (computed tomography), PET (positron emission tomography)/MRI (magnetic resonance imaging) and PET/CT, have increased an interest for reconstruction algorithms which are able to utilize a functional and anatomical information at the same time. In this paper a new method proposed for iterative reconstruction with anatomical prior in emission tomography (ET). The introduced regularization term is a modified anisotropic tensor diffusion filter which has shape-adapted smoothing properties. The filter accommodates available anatomical information which results in enhanced position and image dependent spatial resolution of emission …
Plasma-Enhanced Atomic Layer Deposition Of Ruthenium-Titanium Nitride Mixed-Phase Layers For Direct-Plate Liner And Copper Diffusion Barrier Applications, Adam James Gildea
Plasma-Enhanced Atomic Layer Deposition Of Ruthenium-Titanium Nitride Mixed-Phase Layers For Direct-Plate Liner And Copper Diffusion Barrier Applications, Adam James Gildea
Legacy Theses & Dissertations (2009 - 2024)
Current interconnect networks in semiconductor processing utilize a sputtered TaN diffusion barrier, Ta liner, and Cu seed to improve the adhesion, microstructure, and electromigration resistance of electrochemically deposited copper that fills interconnect wires and vias. However, as wire/via widths shrink due to device scaling, it becomes increasingly difficult to have the volume of a wire/via be occupied with ECD Cu which increases line resistance and increases the delay in signal propagation in IC chips. A single layer that could serve the purpose of a Cu diffusion barrier and ECD Cu adhesion promoter could allow ECD Cu to occupy a larger …