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The Effect Of Composition On The Viscosity, Crystallization And Dissolution Of Simple Borate Glasses And Compositional Design Of Borate Based Bioactive Glasses, Kathryn Lynn Goetschius

Doctoral Dissertations

"Borate glasses have recently been developed for a variety of medical applications, but much less is known about their structures and properties than more common silicate glasses. Melt properties and crystallization tendency for compositions in the Na₂O-CaO-B₂O₃ system were characterized using differential thermal analysis and viscosity measurements. Characteristic viscosity (isokom) temperatures varied with the ratio between the modifier content (Na₂O+CaO) and B₂O₃, particularly at lower temperatures, consistent with the changes in the relative concentrations of tetrahedral borons in the glass structure.

Similar glasses were used to study dissolution processes …

Effect Of Solid Solutions And Second Phases On The Thermal Conductivity Of Zirconium Diboride Ceramics, Gregory John Kenneth Harrington

Doctoral Dissertations

"The research presented in this dissertation is focused on the thermal conductivity (k) of ZrB₂ ceramics. The goal was to develop a better understanding of how various solid solutions and second phases affect the thermal and electrical transport in ZrB₂, with a focus on the effect of C, W, and ZrC. The first study showed C additions improved densification and it was proposed that the reduction of boria was the impetus for this result. Boron carbide was formed by the reaction of excess C with reduced B and its formation was mitigated by the addition of ZrH …

Radio Frequency Interference (Rfi) Modeling Of Complex Modules In Mobile Devices And System-Level Modeling For Transient Esd Simulation, Tianqi Li

Doctoral Dissertations

"The thesis is composed of three papers, which cover the systematic modeling of radio-frequency-interference (RFI) and electro-static-discharge (ESD) problems happened in mobile devices.

In the first paper, an averaging technique is developed, for phase resolved scanning over random fields generated by multiple uncorrelated stochastic sources. This method can separate the field contribution of each noise source and resulting field patterns as if the out-of-interest sources were turned off. The scanned data can be used for emission source localization, far-field pattern calculation and Huygens's box modeling.

In the second paper, using Huygens's Equivalent Theorem a systematic approach for the modeling of …

A Contingency Base Camp Framework Using Model Based Systems Engineering And Adaptive Agents, Dustin Scott Nottage

Doctoral Dissertations

"This research investigates the use of adaptive agents and hybridization of those agents to improve resource allocation in dynamic systems and environments. These agents are applied to contingency bases in an object oriented approach utilizing Model-based Systems Engineering (MBSE) processes and tools to accomplish these goals. Contingency bases provide the tools and resources for the military to perform missions effectively. There has been increasing interest in improving the sustainability and resilience of the camps, as inefficiencies in resource usage increases. The increase in resource usage leads to additional operational costs and added danger to military personnel guarding supply caravans.

The …

First-Principles Investigations Of Iron-Based Alloys And Their Properties, Krista Renee Limmer

Doctoral Dissertations

"Fundamental understanding of the complex interactions governing structure-property relationships in iron-based alloys is necessary to advance ferrous metallurgy. Two key components of alloy design are carbide formation and stabilization and controlling the active deformation mechanism. Following a first-principles methodology, understanding on the electronic level of these components has been gained for predictive modeling of alloys.

Transition metal carbides have long played an important role in alloy design, though the complexity of their interactions with the ferrous matrix is not well understood. Bulk, surface, and interface properties of vanadium carbide, VC_x, were calculated to provide insight for the carbide …

Investigation Of Projectile Coherence Effects In Fully Differential Studies Of 75 Kev Proton - H₂ Collisions, Sachin Sharma

Doctoral Dissertations

"Fully differential cross sections (FDCS) have been measured for single ionization of H₂ by 75 keV proton impact with varying transverse coherence length of the projectiles. As reported in recent years, the scattering angle dependence of the doubly differential cross sections (DDCS) are significantly affected by the projectile coherence properties. The interference structures were observed for the coherent beam, however were absent for an incoherent beam. Interestingly, the FDCS measurements for fixed momentum transfer do not suggest significant differences between the coherent and incoherent cross sections. However, for the FDCS with fixed recoil-ion momentum, clear differences between the two …

Thermal-Fluid Modeling Of The Missouri S&T Reactor, Susan Maria Sipaun

Doctoral Dissertations

"Thermal-fluid modeling of the Missouri University of Science and Technology Reactor (MSTR) was carried out using a computational fluid dynamics code (CFD), STAR-CCM+. First, a three-dimensional parallel-plate model was developed, and the cosine-shaped heat flux was applied to the MSTR core. Simulation results for fluid flow under natural convection condition show coolant temperature and velocity as a function of core power. A characteristic equation for the parallel-plate model was obtained based on Forchheimer's flow equation. The inertial resistance tensor and viscous resistance tensor were found to be 281005 kg/m^4 and 7121.6 kg/m^3 respectively. The MSTR core was then defined as …

Carbon Dioxide - Heavy Oil Systems: Thermodynamics, Transport And Interfacial Stability, Truynh Quoc My Duy Tran

Doctoral Dissertations

"Conventional oil recovery leaves behind around 67% of original oil in place for light oils and all of it for heavy oils. The carbon dioxide flooding process is the cheapest among the recovery methods for the next stage. The interest here lies in recovering heavy oil. When CO₂ dissolves in oil, it increases the volume of oil, squeezes it out of narrow capillaries and the viscosity of oil drops by up to an order of magnitude. Starting with the available data with and without CO₂ in heavy oil, the free volume theory is used to predict these physical …

Seismic Repair Of Bridge Columns With Interlocking Spirals And Fractured Bars, Yang Yang

Doctoral Dissertations

"During earthquakes, reinforced concrete (RC) bridge columns may experience different levels of damage such as cracking, spalling, or crushing of concrete and yielding, buckling, or fracture of reinforcing bars. This study developed and assessed permanent and emergency methods to repair damaged bridge columns with fractured longitudinal reinforcement through experimental and modeling work. The permanent repair method involved replacement of the plastic hinge region by removal of spirals, replacement of longitudinal bar segments by mechanically splicing with new bars segments attached with mechanical couplers, replacement of concrete, and installation of an externally bonded carbon fiber reinforced polymer (CFRP) jacket. The emergency …

A Molecular-Level Approach For Characterizing Water-Insoluble Components Of Ambient Organic Aerosol Particulates Using Ultrahigh-Resolution Mass Spectrometry, A. S. Willoughby, A. S. Wozniak, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

The chemical composition of organic aerosols in the atmosphere is strongly influenced by human emissions. The effect these have on the environment, human health, and climate change is determined by the molecular nature of these chemical species. The complexity of organic aerosol samples limits the ability to study the chemical composition, and therefore the associated properties and the impacts they have. Many studies have addressed the watersoluble fraction of organic aerosols and have had much success in identifying specific molecular formulas for thousands of compounds present. However, little attention is given to the water-insoluble portion, which can contain most of …

Modeling And Simulation Of Continuous Fiber-Reinforced Ceramic Composites, Venkata Bheemreddy

Doctoral Dissertations

"Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior …

Development Of A Nitrogen Incorporated Ultrananocrystalline Diamond Film Based Field Emitter Array For A Flat Panel X-Ray Source, Chrystian Mauricio Posada

Doctoral Dissertations

"As an alternative to conventional X-ray sources, a flat panel transmission X-ray source is being developed. A field emitter array (FEA) prototype to be incorporated as cold cathode in this flat panel X-ray source was fabricated for this work. Using the Particle-in-Cell code OOPIC Pro, an initial FEA was designed through simulations. Based on the simulation results, a FEA prototype was fabricated using conventional microfabrication techniques. Planar nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) films were used as field emitters. This N-UNCD based FEA prototype was composed of 9 pixels distributed in a 3x3 array, with a pixel size of 225x225 µm, and …

Development Of A Flat-Panel X-Ray Source, Edwin Joseph Grant

Doctoral Dissertations

"A novel flat-panel transmission type X-ray source was developed for both medical and industrial use. Depending on the geometry of the given situation, the flat-panel X-ray source could be used in tomography, radiography or tomosynthesis. Furthermore, the unit could be used as a portable X-ray scanner or an integral part of an existing detection system. The design incorporates a field emission cathode made of ultra-nanocrystalline diamonds (UNCD) doped with nitrogen. These field emitters show good electron output at low power and can be deposited over large areas as is the case with carbon nanotube "forest" (CNT) cathodes. This work presents …

Aerogels As Diverse Nanomaterials, Abhishek N. Bang

Doctoral Dissertations

"Aerogels are 3-D light-weight nanoporous materials pursued for their low thermal conductivity, low dielectric constant and high acoustic attenuation. Those exceptional macroscopic properties of aerogels are dependent on the chemical nature of nanoparticles, complex hierarchical solid skeletal framework and porosity. Also, the free space can become host for functional guests such as pharmaceuticals. In chapter I, we investigated randomly mesoporous bio-compatible polymer-crosslinked dysprosia aerogels as drug delivery vehicles and demonstrated storage and release of drugs under physiological conditions. Comparative study with ordered and randomly mesoporous silica showed high drug uptake and slower release rate for random nanostructures (silica or dysprosia) …

Retrievals Of Carbonyl Fluoride (Cof₂) From Ace-Fts And Mipas Spectra And Their Comparison With Slimcat Ctm Calculations, Jeremy Harrison, Shaomin Cai, Anu Dudhia, Martyn Chipperfield, Chris Boone, Peter Bernath

Chemistry & Biochemistry Faculty Publications

The majority of fluorine in the atmosphere has resulted from the anthropogenic emission of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). Most tropospheric fluorine is present in its emitted 'organic' form due to the molecules having long lifetimes. At the top of the stratosphere most of the fluorine is present as the 'inorganic' product HF, which, due to its extreme stability, is an almost permanent reservoir of stratospheric fluorine. The second most abundant stratospheric 'inorganic' fluorine reservoir is carbonyl fluoride (COF₂). The major sources of COF₂ are from the atmospheric degradation of CFC-12 (CCl₂F₂), which is now banned under the …

Semantic Model And Updated Screening Criteria For Polymer Flooding, Laila Dao Saleh

Doctoral Dissertations

"Enhanced oil recovery (EOR) processes produce oil that conventional methods leave behind, where interfacial forces, heavy oil viscosity, and reservoir heterogeneity make it difficult to produce. Many EOR methods are available but usually cannot be used at the same time for a candidate reservoir. Therefore, it is important to select the most appropriate EOR process from among the possible techniques. EOR screening criteria have been created using EOR datasets and serve as the first step to compare the suitability of each technique for a specific reservoir. Most of these datasets are based on field data collected from EOR surveys published …

Pulling On The Thread Of The Insanity Defense, R. George Wright

Villanova Law Review (1956 - )

No abstract provided.

Moocs And Legal Education: Valuable Innovation Or Looming Disaster?, Philip G. Schrag

Villanova Law Review (1956 - )

No abstract provided.

Automated Classification Of Malignant Melanoma Based On Detection Of Atypical Pigment Network In Dermoscopy Images Of Skin Lesions, Nabin K. Mishra

Doctoral Dissertations

“Melanoma causes more deaths than any other form of skin cancer. Early melanoma detection is important to prevent progression to a more deadly stage. Automated computer-based identification of melanoma from dermoscopic images of skin lesions is the most efficient method in early diagnosis. An automated melanoma identification system must include multiple steps, involving lesion segmentation, feature extraction, feature combination and classification. In this research, a classifier-based approach for automatically selecting a lesion border mask for segmentation of dermoscopic skin lesion images is presented. A logistic regression based model selects a single lesion border mask from multiple border masks generated by …

Degradable Nanocomposite Preformed Particle Gel For Chemical Enhanced Oil Recovery Applications, Paul Tongwa

Doctoral Dissertations

”This work presents two new materials that can be potentially used in conformance control to increase ultimate oil recovery from mature oilfields.

The first product is a degradable nanocomposite preformed particle gel for enhanced in-depth mobility control. Three different types of degradable nanocomposite preformed particle gels were synthesized. These three nanocomposite hydrogels were made using Laponite XLG, Calcium Montmorillonite, and Sodium Montmorillonite nanomaterials. It was observed that after degradation, Laponite XLG nanocomposite hydrogels had the highest post-degradation viscosity (4437 cp), followed by sodium nanocomposite hydrogels (129 cp), and lastly calcium nanocomposite hydrogels (75.5 cp). Thus, degradable Laponite XLG nanocomposite hydrogels …

Experimental And Computational Investigation Of Flow Of Pebbles In A Pebble Bed Nuclear Reactor, Vaibhav B. Khane

Doctoral Dissertations

"The Pebble Bed Reactor (PBR) is a 4th generation nuclear reactor which is conceptually similar to moving bed reactors used in the chemical and petrochemical industries. In a PBR core, nuclear fuel in the form of pebbles moves slowly under the influence of gravity. Due to the dynamic nature of the core, a thorough understanding about slow and dense granular flow of pebbles is required from both a reactor safety and performance evaluation point of view.

In this dissertation, a new integrated experimental and computational study of granular flow in a PBR has been performed. Continuous pebble re-circulation experimental set-up, …

Energy Efficient Security And Privacy Management In Sensor Clouds, Vimal Kumar

Doctoral Dissertations

"Sensor Cloud is a new model of computing for Wireless Sensor Networks, which facilitates resource sharing and enables large scale sensor networks. A multi-user distributed system, however, where resources are shared, has inherent challenges in security and privacy. The data being generated by the wireless sensors in a sensor cloud need to be protected against adversaries, which may be outsiders as well as insiders. Similarly the code which is disseminated to the sensors by the sensor cloud needs to be protected against inside and outside adversaries. Moreover, since the wireless sensors cannot support complex, energy intensive measures, the security and …

Graphite Aerogels And The Formation Mechanism Of Unusual Micron-Sized Rod And Helical Structures, Clarissa Ann Wisner

Doctoral Dissertations

"Pyrolysis at 800 ºC under argon has shown that polyimide (PI), polyacrylonitrile (PAN), polydicyclopentadiene (DCPD) and polybenzoxazine (PBO) aerogels are all viable alternatives to traditional resorcinol-formaldehyde (RF) aerogels as precursors to amorphous carbon aerogels. Subsequent high temperature pyrolysis at 2300 ºC of such carbon aerogels under helium has shown that amorphous carbon from PI and PBO yields the highest degree of graphitization, whereas from RF aerogels yields the lowest.

Those two types of graphite aerogels include also a high concentration of micron-size columnar and helical (screw-like) structures, whose formation is favored by macroporosity and high nitrogen retention in the 800 …

Hardware Integration Of Ultracapacitor Based Energy Storage To Provide Grid Support And To Improve Power Quality Of The Distribution Grid, Deepak Somayajula

Doctoral Dissertations

"Grid integration of distributed energy resources (DERs) is increasing rapidly. Integration of various types of energy storage technologies like batteries, ultracapacitors (UCAPs), superconducting magnets and flywheels to support intermittent DERs, such as solar and wind, in order to improve their reliability is becoming necessary. Of all the energy storage technologies UCAPs have low energy density, high power density and fast charge/discharge characteristics. They also have more charge/discharge cycles and higher terminal voltage per module when compared to batteries. All these characteristics make UCAPs ideal choice for providing support to events on the distribution grid which require high power for short …

Characterization And Fabrication Of Spoke Cavities For High-Velocity Applications, C. S. Hopper, Hyekyoung Park, Jean R. Delayen

Physics Faculty Publications

A 500 MHz, velocity-of-light, two-spoke cavity has been designed and optimized for possible use in a compact light source [1]. Here we present the mechanical analysis and steps taken in fabrication of this cavity at Jefferson Lab.

A Unified Bond Theory, Probabilistic Meso-Scale Modeling, And Experimental Validation Of Deformed Steel Rebar In Normal Strength Concrete, Chenglin Wu

Doctoral Dissertations

"Bond between deformed rebar and concrete is affected by rebar deformation pattern, concrete properties, concrete confinement, and rebar-concrete interfacial properties. Two distinct groups of bond models were traditionally developed based on the dominant effects of concrete splitting and near-interface shear-off failures. Their accuracy highly depended upon the test data sets selected in analysis and calibration. In this study, a unified bond model is proposed and developed based on an analogy to the indentation problem around the rib front of deformed rebar. This mechanics-based model can take into account the combined effect of concrete splitting and interface shear-off failures, resulting in …

Synthesis Of Novel C-4 Disubstituted Β-Lactams Through Staudinger Cycloaddition Reaction, Robert Rodriguez, Anjali Nambiar, Ram N. Yadav, Bimal K. Banik

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Chemistry)

Synthesis of novel C-4 disubstituted beta-lactam that has N-methyl pyrrole system has been achieved through Staudinger cycloaddition reaction of acid chloride and imine. Interestingly, this reaction has produced a single stereoisomer.

Changes In Fish Populations In The Lower Canyons Of The Rio Grande, Gary P. Garrett, Robert Edwards

School of Integrative Biological & Chemical Sciences (Formerly Dept. of Biology)

The Lower Canyons of the Rio Grande suffer from environmental degradation that has negatively impacted native fish populations and their distributions. Macrhybopsis aestivalis (speckled chub), Notropis jemezanus (Rio Grande shiner), Rhinichthys cataractae (longnose dace) and Cycleptus elongatus (blue sucker) populations appear to have suffered recent declines. Although diminished water quantity is likely an important factor in these declines, related changes in channel morphology precipitated by massive stands of Arundo donax (giant reed) and Tamarix sp. (salt cedar) may also be responsible. These invasive exotics have essentially channelized the river, disrupted normal sediment distribution and reduced shallow, low-velocity habitats. Much of …

Collaborative Efforts: Raising Students’ Multicultural Consciousness Through Academic Affairs And Student Affairs Partnerships, Shannon R. Dean

Journal of Higher Education & Student Affairs

This article presents the need to shift language around multicultural competence to multicultural consciousness in the context of college students’ learning and development. Engaging in collaboration between academic and student affairs around multicultural consciousness supports student learning. Finally, the article outlines examples of three collaborations that can enrich students’ learning and development in the area of multicultural consciousness.

Fatherhood In Brazil, Bangladesh, Russia, Japan, And Australia, David W. Shwalb, Barbara J. Shwalb

Online Readings in Psychology and Culture

This article illustrates that the roles of fathers are highly variable and context-dependent. Research data from five diverse societies (Brazil, Bangladesh, Russia, Japan, and Australia) show that fathers, fathering, and fatherhood differ within societies according to eight types of contextual influence. Examples are provided of each contextual factor: (1) geographical location (e.g., dispersion of fathers across huge land masses in Russia and Australia; impact of dense populations in Japan and Bangladesh); (2) long-term historical legacies (centuries of patriarchy in Brazil) and short-term historical events (fall of communism in Russia); (3) family characteristics (joint, extended families of Bangladesh; small Japanese families); …