Digital Commons Network^™

Multifrequency Averaging In Power Electronic Systems, Fei Pan

Theses and Dissertations--Electrical and Computer Engineering

Power electronic systems have been widely used in the electrical power processing for applications with power levels ranging from less than one watt in battery-operated portable devices to more than megawatts in the converters, inverters and rectifiers of the utility power systems. These systems typically involve the passive elements such as inductors, capacitors, and resistors, the switching electronic components such as IGBTs, MOSFETS, and diodes, and other electronic circuits. Multifrequency averaging is one of the widely used modeling and simulation techniques today for the analysis and design of power electronic systems. This technique is capable of providing the average behavior …

Coordinated Voltage And Reactive Power Control Of Power Distribution Systems With Distributed Generation, Esa A. Paaso

Theses and Dissertations--Electrical and Computer Engineering

Distribution system voltage and VAR control (VVC) is a technique that combines conservation voltage reduction and reactive power compensation to operate a distribution system at its optimal conditions. Coordinated VVC can provide major economic benefits for distribution utilities. Incorporating distributed generation (DG) to VVC can improve the system efficiency and reliability. The first part of this dissertation introduces a direct optimization formulation for VVC with DG. The control is formulated as a mixed integer non-linear programming (MINLP) problem. The formulation is based on a three-phase power flow with accurate component models. The VVC problem is solved with a state of …

Field-Scale Water And Solute Transport, Yang Yang

Theses and Dissertations--Plant and Soil Sciences

Spatial variability of soil properties complicates the understanding of water and solute transport at the field scale. This study evaluated the impact of land use, soil surface roughness, and rainfall characteristics on water transport and Br^- leaching under field conditions by means of a new experimental design employing scale-dependent treatment distribution. On a transect with two land use systems, i.e., cropland and grassland, rainfall intensity and the time delay between Br^- application and subsequent rainfall were arranged in a periodically repetitive pattern at two different scales. Both scales were distinct from the scale of surface roughness as described …

Fusarium Head Blight Resistance And Agronomic Performance In Soft Red Winter Wheat Populations, Daniela Sarti Dvorjak

Theses and Dissertations--Plant and Soil Sciences

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)], is recognized as one of the most destructive diseases of wheat (Triticum aestivum L. and T. durum L.) and barley (Hordeum vulgare L.) worldwide. Breeding for FHB resistance must be accompanied by selection for desirable agronomic traits. Donor parents with two FHB resistance quantitative trait loci (QTL) Fhb1 (chromosome 3BS) and QFhs.nau-2DL (chromosome 2DL) were crossed to four adapted SRW wheat lines to generate backcross and forward cross progeny. F₂ individuals were genotyped and assigned to 4 different groups according to presence/ absence of …

Improving Methods For The Successful Establishment Of Switchgrass, Whitney Marie Monin

Theses and Dissertations--Plant and Soil Sciences

Our research investigated whether priming switchgrass seeds with water or ethephon would increase stand establishment in the field. ‘Alamo’ seed germinated faster and grew taller than ‘Cave-in-Rock.Seeds primed for six days in water or for one day in ethephon 10 mM had the greatest seedling densities. In growth chamber environments seed priming were tested to hasten germination velocity. Seeds primed for two, four or six days in water germinated faster than unprimed seeds. Ethephon treatments reduced overall germination and germination velocity. Accent and Accent Q herbicides containing nicosulfuron are used to control weeds. To test ‘Alamo’ sensitivity to these herbicides, …

Electron And Ion Spectroscopy Of Metal Hydrocarbon Complexes, Sudesh Kumari

Theses and Dissertations--Chemistry

Metal-hydrocarbon complexes were prepared in a laser-vaporization molecular beam source and studied by single-photon zero electron kinetic energy (ZEKE) and mass-analyzed threshold ionization (MATI) spectroscopy. The ionization energies and vibrational frequencies of the metal complexes were measured from the ZEKE and MATI spectra. Metal-ligand bonding and low-lying electronic states of the neutral and ionized complexes were analyzed by combining the spectroscopic measurements with quantum chemical calculations and spectral simulations.

In this dissertation, the metal complexes of mesitylene, aniline, cyclooctatetraene, benzene, ethene, and propene were studied. For each complex, different effects from metal coordination have been identified. Although metal-bis(mesitylene) sandwich complexes …

Structures And Electronic States Of Small Group 3 Metal Clusters, Lu Wu

Theses and Dissertations--Chemistry

Group 3 metal clusters are synthesized by laser vaporization in a pulsed cluster beam source and identified with laser ionization time-of-flight mass spectrometry. The adiabatic ionization energies and vibrational frequencies of these clusters are measured using mass-analyzed threshold ionization (MATI) spectroscopy. Their structures and electronic states are determined by combining the MATI spectra with quantum chemical calculations and spectral simulations. This dissertation focuses on the study of several small molecules, which include LaO₂, La₂, M₂O₂, M₃O₄, M₃C₂, and La₃C₂O, where …

Electrode And Electrolyte Additives For Lifetime Extension In Lithium-Ion Batteries, Kishore Anand Narayana

Theses and Dissertations--Chemistry

Lithium-ion batteries (LIBs) are the most commonly used type of rechargeable batteries with a global market estimated at $11 billion, which is predicted to grow to $60 billion by 2020. The global commercialization of Li-ion batteries is impeded by issues such as poor cycle life (5000 cycles achieved in some LIBs) in high energy and power density applications because of the rising internal resistance due to aging and safety concerns such as overcharge which ultimately leads to thermal runaway and explosions. A battery’s performance mainly depends on external factors such as electrode thickness and degree of compacting, and the type …

A Study Of Lignin Depolymerization By Selective Cleavage Of The Cα-Cβ Linkages In Lignin Model Compounds Via Baeyer-Villiger Oxidation & An Investigation Of The Channeling Reaction In Nitrogen-Doped Multiwalled Carbon Nanotubes (N-Mwcnts), Nikhil Dilip Patil

Theses and Dissertations--Chemistry

A STUDY OF LIGNIN DEPOLYMERIZATION BY SELECTIVE CLEAVAGE OF THE Cα-Cβ LINKAGES IN LIGNIN MODEL COMPOUNDS VIA BAEYER-VILLIGER OXIDATION

Lignin is amorphous aromatic polymer derived from plants and is a potential source of fuels and bulk chemicals. Herein, we present a survey of reagents for selective stepwise oxidation of lignin model compounds. Specifically, we have targeted the oxidative cleavage of Cα-Cβ bonds as a means to depolymerize lignin and obtain useful aromatic compounds. In this work, we prepared several lignin model compounds that possess structures, characteristic reactivity, and linkages closely related to the parent lignin polymer. We observed that selective …

Cross Photoreaction Of Pyruvic And Glyoxylic Acids In Model Aqueous Aerosols, Shasha Xia

Theses and Dissertations--Chemistry

Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. Aerosols from natural and anthropogenic sources can be primary organic aerosols (POA), which are directly emitted to the atmosphere, or secondary organic aerosols (SOA) that are formed from chemical reactions of gas-phase precursors. At variance with the well investigated formation of SOA from gas phase precursors, the chemistry of aqueous SOAs that contribute to the total SOA budget remains unknown. Field measurements have revealed that carboxylic, dicarboxylic and oxocarboxylic acids are abundant species present in SOAs. This thesis …

Salen Aluminum Compounds In The Dealkylation And Detection Of Organophosphates, Rahul R. Butala

Theses and Dissertations--Chemistry

The focus of this dissertation is the use of aluminum Schiff base compounds, Salen(^tBu)AlBr (SAB), in the dealkylation and detection of organophosphates (OPs). Three SAB compounds, Salen(^tBu)AlBr (1), Salpen(^tBu)AlBr (2), and Salophen(^tBu)AlBr (3) were used to dealkylate a variety of trialkyl OPs. These reactions lead to unique organic-soluble aluminum phosphate compounds containing six-coordinate aluminum. Examples include [salen(^tBu)AlOP(O)(OCH₃)₂]_n (4), [salen(^tBu)AlOP(O)(OCH₂CH₃)₂]_n (5), [salen(^tBu)AlOP(O)(OPh)₂]_{n …}

Quartz Crystal Microbalance Investigation Of Cellulosome Activity From Clostridium Thermocellum On Model Cellulose Films, Shanshan Zhou

Theses and Dissertations--Chemical and Materials Engineering

The cost of deconstructing cellulose into soluble sugars is a key impediment to the commercial production of lignocellulosic biofuels. The use of the quartz crystal microbalance (QCM) to investigate reaction variables critical to enzymatic cellulose hydrolysis is investigated here, extending previous studies of fungal cellulase activity for the first time to whole cell cellulases. Specifically, the activity of the cellulases of Clostridium thermocellum, which are in the form of cellulosomes, was investigated. To clearly differentiate the activity of free cellulosome and cell-bound cellulosome, the distribution of free cellulosome and cell-bound cellulosome in crude cell broth at different growth stages …

Layer-By-Layer Assemblies For Membrane-Based Enzymatic Catalysis, Andrew R. Tomaino

Theses and Dissertations--Chemical and Materials Engineering

While considerable progress has been made towards understanding the effect that membrane-based layer-by-layer (LbL) immobilizations have on the activity and stability of enzymatic catalysis, detailed work is required in order to fundamentally quantify and optimize the functionalization and operating conditions that define these properties. This work aims to probe deeper into the nature of transport mechanisms by use of pressure-induced, flow-driven enzymatic catalysis of LbL-functionalized hydrophilized poly(vinyldiene) (PVDF)-poly(acrylic acid) (PAA)-poly(allylamine hydrochloride) (PAH)-glucose oxidase (GOx) membranes. These membranes were coupled in a sealed series following cellulose acetate (CA) membranes for the elimination of product accumulation within the feed-side solution during operation. …

A Multidisciplinary Techno-Economic Decision Support Tool For Validating Long-Term Economic Viability Of Biorefining Processes, Sumesh Sukumara

Theses and Dissertations--Chemical and Materials Engineering

Increasing demand for energy and transportation fuel has motivated researchers all around the world to explore alternatives for a long-term sustainable source of energy. Biomass is one such renewable resource that can be converted into various marketable products by the process of biorefining. Currently, research is taking strides in developing conversion techniques for producing biofuels from multiple bio-based feedstocks. However, the greatest concern with emerging processes is the long-term viability as a sustainable source of energy. Hence, a framework is required that can incorporate novel and existing processes to validate their economic, environmental and social potential in satisfying present energy …

Methods Development In Biological Mass Spectrometry: Application In Glycoproteomics, Sanja Trajkovic

Theses and Dissertations--Chemistry

Proteomics refers to global characterization of the full set of proteins present in a biological sample. Various analytical disciplines contribute to proteomics but mass spectrometry became method of choice for analysis of complex protein samples.

Mass spectrometry allows for high throughput analysis of the proteome but, moreover, it has the ability to acquire higher-order information such as post-translational modifications (PTM). Glycosylation is the most abundant PTM on eukaryotic proteins.

This dissertation will focus on method development for structural proteomics that will be utilized to explain the glycoproteome of obligate intracellular protozoan parasite Toxoplasma gondii as a model system.

Optimization of …

Laser Spectroscopy Of Radicals Containing Group Iiia And Va Elements, Robert A. Grimminger

Theses and Dissertations--Chemistry

Radicals are interesting to study because of importance in so many processes such as semiconductor growth or stellar evolution. Laser induced fluorescence (LIF) and wavelength resolved emission spectra of jet cooled HPS, HAsO, AsD₂, H₂PS, and F₂BO have been measured using the pulsed discharge jet technique.

Several bands in the à ¹A′′ − X̃ ¹A′ transition of HPS were observed and assigned with the help of ab initio calculations. The ab initio geometries showed that HPS does not follow Walsh’s predictions for the angle change upon electronic excitation; Walsh predicts an increase …

Nuclear Structure In Transitional Regions: Studies Of ¹³²,¹³⁴Xe And Lifetimes In The Stable Zr Nuclei With The (N,N′Γ) Reaction, Erin Elizabeth Peters

Theses and Dissertations--Chemistry

Nuclei at closed shells tend to be spherical and are well-described by the shell model, while those between closed shells are deformed and better described by collective models. The nuclei which are in transitional regions between spherical and deformed may be studied to gain insight into the nature of this transition. The stable isotopes of zirconium and xenon span such transitional regions and are the subject of this dissertation. Gamma-ray spectroscopy following inelastic neutron scattering has been performed on the stable isotopes of Zr as well as ^132,134Xe at the University of Kentucky Accelerator Laboratory. Level lifetimes have been …

Applications Of Gas Chromatography/Mass Spectrometry And Capillary Electrophoresis For The Analysis Of Lignocellulosic Biomass Pretreatment, Dawn M. Kato

Theses and Dissertations--Chemistry

The focus of this dissertation centers on the development and applications of gas chromatography/mass spectrometry and capillary electrophoresis methodologies to quantify monomeric compositions of the β-O-4 linkages in lignin. Pretreatment is a required step in the utilization of lignocellulosic biomass for biofuels. Lignin is the target of pretreatment because it hinders the accessibility of enzymes and chemicals to cellulose. The effects of pretreatment are commonly assessed utilizing enzymatic saccharification and lignin assays. However, these techniques do not elucidate the effects of pretreatment on the monomeric make up of lignin.

The overarching hypothesis of this dissertation is that changes in individual …

Temperature-Dependent Tunable Photoluminescence Properties Of Carbon Nanodots Derived From Polyethylene Glycol, Sin Hea Yeom

Theses and Dissertations--Chemistry

Fluorescent carbon dots (C-dots) are well known for their low cell-cytotoxicity, biocompatibility, low preparation cost, excitation dependent photoluminescence, and excellent photostability. Typically, raw C-dots have low quantum efficiency and thus researchers have been utilizing biocompatible polymers such as polyethylene glycol (PEG) as a passivation agent in order to increase fluorescence signal. In this work, we report fluorescent self-passivated carbon nanodots (CNDs) synthesized from PEG by using it as a carbon source as well as a passivating agent. Importantly, the addition of graphene quantum dots (GQDs) during the synthesis of self-passivated CNDs can tune photoluminescence property. The results of bioimaging and …

Addressing Public Health Risks Of Persistent Pollutants Through Nutritional Modulation And Biomimetic Nanocomposite Remediation Platforms, Bradley J. Newsome

Theses and Dissertations--Chemistry

Due to their relative chemical stability and ubiquity in the environment, chlorinated organic contaminants such as polychlorinated biphenyls (PCBs) pose significant health risks and enduring remediation challenges. Engineered nanoparticles (NPs) provide a novel platform for sensing/remediation of these toxicants, in addition to the growing use of NPs in many industrial and biomedical applications, but there remains concern for their potential long-term health effects. Research highlighted herein also represents a transdisciplinary approach to address human health challenges associated with exposure to PCBs and NPs. The objectives of this dissertation research are two-fold, 1) to develop effective methods for capture/sensing and remediation …

Valuation In Light Of Uncertainty: How Stock Option Pricing Models Can Inform More Accurate Valuation Discounts For Built-In Gains, Rebecca N. Morrow

Kentucky Law Journal

No abstract provided.

4% Absent = 100% Disaster: Why The Math Doesn't Add Up On Fixed Attendance Leave Policies Under The Fmla, Laraclay Parker

Kentucky Law Journal

No abstract provided.

Subprime Scriveners, Milan Markovic

Kentucky Law Journal

Although mortgage-backed securities ("MBS") and other financial products that nearly caused the collapse of the global financial system could not have been issued without attorneys, the legal profession's role in the financial crisis has received relatively little scrutiny.

This Article focuses on lawyers' preparation of MBS offering documents that misrepresented the lending practices of mortgage loan originators. While attorneys may not have known that many MBS would become toxic, they lacked incentives to inquire into the shoddy lending practices of prominent originators, such as Washington Mutual Bank ('WaMu"), when they and their clients were reaping considerable profits from MBS offerings. …

Contribution Of Nucleus Accumbens Core To Impulsive Choice: Role Of Dopamine And Glutamate Systems, Justin R. Yates

Theses and Dissertations--Psychology

Impulsive choice refers to the inability to delay gratification and is associated with increased drug abuse vulnerability. Understanding the underlying neural mechanisms linking impulsive choice and drug abuse can contribute to improved treatment options for individuals with substance use disorders. Evidence suggests a major role for nucleus accumbens core (NAcc) in impulsive choice and the reinforcing effects of drugs of abuse. The neurotransmitters glutamate (Glu) and dopamine (DA) are implicated in the neural adaptations observed in drug addiction; however, the role of intra-NAcc Glu and DA in impulsive choice is unclear. Rats were trained in a delay discounting task, in …

Universal Constraints On 2d Cfts And 3d Gravity, Joshua D. Qualls

Theses and Dissertations--Physics and Astronomy

We study constraints imposed on a general unitary two-dimensional conformal field theory by modular invariance. We begin with a review of previous bounds on the conformal dimension Delta₁ of the lowest primary operator assuming unitarity, a discrete spectrum, modular invariance, c_L, c_R > 1, and no extended chiral algebra. We then obtain bounds on the conformal dimensions Delta₂, Delta₃ using no additional assumptions. We also show that in order to find a bound for Delta₄ or higher Delta_n, we need to assume a larger minimum value for c_tot that grows …

A Study Of The Lithium Ionic Conductor Li5La3Ta2O12: From Synthesis Through Materials And Transport Characterization, Brian M. Ray

Theses and Dissertations--Physics and Astronomy

The ionic conductivity of the lithium ionic conductor, Li5La3Ta2O12, is studied in an attempt to better understand the intrinsic bulk ionic conductivity and extrinsic sample dependent contributions to the ionic conductivity, such as grain boundary effects and the electrode-electrolyte interface. To characterize the material, traditional AC impedance spectroscopy studies were performed as well novel in-situ nanoscale transport measurements. To perform the nanoscale measurements, higher quality samples were required and new synthesis techniques developed. The results of these new synthesis techniques was samples with higher densities, up to 96% of theoretical, and slightly higher room temperature ionic conductivity, 2x10^−5 S/cm. By …

The Structure Of Broad Line Region And The Effects Of Cooling Function In Active Galactic Nuclei, Ye Wang

Theses and Dissertations--Physics and Astronomy

Active Galactic Nuclei (AGNs) are the most mystic objects in the universe. They are usually very far away from our Galaxy, which means that they are ancient objects. They are also luminous and have unique features in their spectra. Studying AGNs helps understanding the early universe and the evolution of galaxies. This Dissertation aims to research the structure of AGNs and the cooling function in the AGNs environment.

I first investigate what optical/ultraviolet spectroscopic features would be produced by Broad-line Region (BLR) clouds crossing our line of sight to the accretion disk, the source of the optical/UV continuum. This research, …

A Systematic Transport And Thermodynamic Study Of Heavy Transition Metal Oxides With Hexagonal Structure, Kamal H. Butrouna

Theses and Dissertations--Physics and Astronomy

There is no apparent, dominant interaction in heavy transition metal oxides (TMO), especially in 5d-TMO, where all relevant interactions are of comparable energy scales, and therefore strongly compete. In particular, the spin-orbit interaction (SOI) strongly competes with the electron-lattice and on-site Coulomb interaction (U). Therefore, any tool that allows one to tune the relative strengths of SOI and U is expected to offer an opportunity for the discovery and study of novel materials. BaIrO₃ is a magnetic insulator driven by SOI whereas the isostructural BaRuO₃ is a paramagnetic metal. The contrasting ground states have been shown to result …

Reevaluation Of The Aapm Tg-43 Brachytherapy Dosimetry Parameters For An 125I Seed, And The Influence Of Eye Plaque Design On Dose Distributions And Dose-Volume Histograms, Prakash Aryal

Theses and Dissertations--Physics and Astronomy

The TG-43 dosimetry parameters of the Advantage^{TM 125}I model IAI-125A brachytherapy seed were studied. An investigation using modern MCNP radiation transport code with updated cross-section libraries was performed. Twelve different simulation conditions were studied for a single seed by varying the coating thickness, mass density, photon energy spectrum and cross-section library. The dose rate was found to be 6.3% lower at 1 cm in comparison to published results. New TG-43 dosimetry parameters are proposed.

The dose distribution for a brachytherapy eye plaque, model EP917, was investigated, including the effects of collimation from high-Z slots. Dose distributions for …

Magneto-Optical Effects And Precision Measurement Physics: Accessing The Magnetic Faraday Effect Of Polarized 3He With A Triple Modulation Technique, Gretchen Phelps

Theses and Dissertations--Physics and Astronomy

This work is comprised of the study of two magneto-optical phenomena: the Kerr effect and the Faraday effect. Neutron physics experiments often utilize polarized neutrons, and one method to generate or guide polarized neutrons involves the use of a system of magnetic super-mirrors. Experience shows that the magnetization of the super-mirror may decay with time; therefore, we implemented the surface magneto-optical Kerr effect (SMOKE) to study the temporal behavior of the magnetization of a magnetized remnant super-mirror sample, where a sensitivity of 0.1 mrad was obtained. Unique to our set-up was the method in which the various magnetization directions were …