Digital Commons Network^™

Electron Beam Characterization Of Carbon Nanostructures, Eric Samuel Mandell

Doctoral Dissertations

"Atom-thick carbon nanostructures represent a class of novel materials that are of interest to those studying carbon's role in fossil fuel, hydrogen storage, scaled-down electronics, and other nanotechnology. Electron microscope images of "edge-on" graphene sheets show linear image features due to the projected potential of the sheets. Here, intensity profiles along these linear features can measure the curvature of the sheet, as well as the shape of the sheet (i.e. hexagonal, triangular). Also, electron diffraction powder profiles calculated for triangular graphene sheet shapes show a broadening of the low frequency edge of diffraction rings, in comparison to those calculated for …

Field And Laboratory Investigation Of Ozone-Indoor Surface Reactions: Secondary Emissions Inventory And Implications For Indoor Air Quality, Hong Wang

Doctoral Dissertations

"Interfacial chemistry greatly influences human exposure to reactants and products in indoor environments. Emissions of volatile organic compounds, as a result of ozone-surface interactions, can lower an occupant's exposure to ozone, but increase indoor concentrations of odorous and carcinogenic compounds. Therefore, investigation of ozone-surface interactions are necessary for better understanding and controlling exposure to ozone and the products of indoor surface chemistry. In this dissertation, field experiments were conducted in five homes in three seasons to quantify ozone-initiated secondary emission rates (SERs), yields surface reaction probabilities and study their temporal trends"--Abstract, page iv.

Incipient Continental Rifting: Insights From The Okavango Rift Zone, Northwestern Botswana, Baraka D. Kinabo

Doctoral Dissertations

"In this dissertation aeromagnetic, gravity, and Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) data from the Okavango Rift Zone in northwest Botswana are used to map the distribution of rift and basement structures. The distribution of these structures provide useful insights into the early stages of continental rifting. The objectives of this study are (1) assessing the role of pre-existing structures on rift basin development, (2) characterizing the geometry of the nascent rift basins, (3) documenting fault growth and propagation patterns, and (4) investigating the border fault development"--Abstract, page iv.

New Techniques To Improve Power Quality And Evaluate Stability In Modern All-Electric Naval Ship Power Systems, Peng Xiao

Doctoral Dissertations

"This dissertation focuses on two crucial issues in the design and analysis of the power electronic systems on modern all-electric naval ships, i.e., power quality control and stability evaluation. It includes three papers that deal with active power filter topology, active rectifier control, and impedance measurement techniques, respectively. To mitigate harmonic currents generated by high-power high-voltage shipboard loads such as propulsion motor drives, the first paper proposes a novel seven-level shunt active power filter topology, which utilizes tapped reactors for parallel operations of switching devices. The multi-level system has been implemented in both regular digital simulation and real-time digital simulator …

Neural Network Control Of Nonstrict Feedback And Nonaffine Nonlinear Discrete-Time Systems With Application To Engine Control, Jonathan B. Vance

Doctoral Dissertations

"In this dissertation, neural networks (NN) approximate unknown nonlinear functions in the system equations, unknown control inputs, and cost functions for two different classes of nonlinear discrete-time systems. Employing NN in closed-loop feedback systems requires that weight update algorithms be stable...Controllers are developed and applied to a nonlinear, discrete-time system of equations for a spark ignition engine model to reduce the cyclic dispersion of heat release"--Abstract, page iv.

The Leaching Behavior Of Arsenic, Selenium And Other Trace Elements In Coal Fly Ash, Tian Wang

Doctoral Dissertations

"The goals of this study are four fold, they are: (1) to investigate the leaching behavior of arsenic and selenium from fly ash as well as their affecting factors; (2) to analyze the speciation of arsenic and selenium in fly ash leachate; (3) to develop a modeling approach to quantify the availability and stability of trace cationic elements in fly ash; (4) to apply this model to describe the leaching/adsorption behavior of arsenic and selenium on fly ash, as well as the calcium effect on arsenic (V) adsorption process"--Abstract, page iv.

Effects Of Combined Exposure To Ethanol And Ionizing Radiation On The Antioxidant Status Of In Vitro And In Vivo Models, Joshua Ogony

Doctoral Dissertations

"Ethanol and ionizing radiation exposure are independently known to cause tissue damage through various mechanisms. Non-enzymatic and enzymatic metabolism of ethanol, the latter via the cytochrome P₄₅₀2E1-dependent pathway, produces free radicals which deplete cellular glutathione (GSH). Ionizing radiation exposure has been shown to induce lipid peroxidation, DNA damage, protein oxidation, and GSH depletion, as well. It was postulated that initial exposure to ethanol, followed by ionizing radiation, would result in heightened oxidative stress. The in vitro model used in this investigation was HepG2 cells (human hepatocellular liver carcinoma cell line), while the in vivo model was Cd-1 mice"--Abstract, page iii.

Mechanical Integrity And Behavior Of Thin Films And Their Applications In Mems, Gang Duan

Doctoral Dissertations

"Electric actuated thin films are widely used in micro-electromechanical systems (MEMS) such as radio frequency switches (RF-switches), micro-pumps and valves, and electrostatic actuators. This dissertation will focus on the operation of a MEMS-RF-switch. In a typical MEMS-RF-switch, a mechanically suspended 1-D rectangular or 2-D axisymmetric thin film is pulled by an electrostatic voltage (V₀) applied to an electrode-pad directly underneath. When V₀ exceeds a certain "pull-in" threshold, V₀*, the thin film makes direct contact with the pad so that either an "on" or "off" signal is induced, and when the voltage is removed, the thin film resumes its original undeformed …

A Computational Theory For The Generation Of Solutions During Early Conceptual Design, Cari R. Bryant

Doctoral Dissertations

"Advancement in technology is usually made by building on previous experiences and learning from past successes and failures. However, knowledge transfer in the broad field of product design is often difficult to accomplish. Research has shown that successful component configurations, observed from existing products, can be dissected and stored for reuse; but few computational tools exist to assist designers during the conceptual phase of design. Many well-known manual methods (e.g. brainstorming, intrinsic and extrinsic searches, and morphological analysis) rely heavily on individual bias and experience and are often time intensive, laborious tasks that may not catch solutions that are functionally …

The Development Of Hybrid Intelligent Systems For Technical Analysis Based Equivolume Charting, Thira Chavarnakul

Doctoral Dissertations

"This dissertation proposes the development of a hybrid intelligent system applied to technical analysis based equivolume charting for stock trading. A Neuro-Fuzzy based Genetic Algorithms (NF-GA) system of the Volume Adjusted Moving Average (VAMA) membership functions is introduced to evaluate the effectiveness of using a hybrid intelligent system that integrates neural networks, fuzzy logic, and genetic algorithms techniques for increasing the efficiency of technical analysis based equivolume charting for trading stocks"--Introduction, page 1.

Analysis Of The Holistic Impact Of The Hydrogen Economy On The Coal Industry, Shannon Perry Lusk

Doctoral Dissertations

"As gas prices soar and energy demand continues to grow amidst increasingly stringent environmental regulations and an assortment of global pressures, implementing alternative energy sources while considering their linked economic, environmental and societal impacts becomes a more pressing matter. The Hydrogen Economy has been proposed as an answer to meeting the increasing energy demand for electric power generation and transportation in an environmentally benign way. Based on current hydrogen technology development, the most practical feedstock to fuel the Hydrogen Economy may prove to be coal via hydrogen production at FutureGen plants. The planned growth of the currently conceived Hydrogen Economy …

Boffin's Books And Darwin's Finches: Victorian Cultures Of Collecting, Michael W. Hancock '89

Doctoral Dissertations

Although wealthy continental virtuosos had passionately and selectively accumulated a variety of natural and artificial objects from the Renaissance onwards, not until the nineteenth century did collecting become a conspicuous national pastime among all classes in Britain. As industry and empire made available many new and exotic goods for acquisition and display, the collection as a cultural form offered the Victorians a popular strategy of self-fashioning that was often represented in the literature of the age as a source of prestige and social legitimation. Through interdisciplinary readings of Victorian fiction, narrative nonfiction, and poetry, my study examines how textual representations …

Membrane Systems With Limited Parallelism, Bianca Daniela Popa

Doctoral Dissertations

Membrane computing is an emerging research field that belongs to the more general area of molecular computing, which deals with computational models inspired from bio-molecular processes. Membrane computing aims at defining models, called membrane systems or P systems, which abstract the functioning and structure of the cell. A membrane system consists of a hierarchical arrangement of membranes delimiting regions, which represent various compartments of a cell, and with each region containing bio-chemical elements of various types and having associated evolution rules, which represent bio-chemical processes taking place inside the cell.

This work is a continuation of the investigations aiming to …

Investigation Of Ethanol Dehydration In A Microscale Pervaporation Process, Sudhir Ramprasad

Doctoral Dissertations

Challenges due to surface tension effects for vaporization in microchannels have restricted the implementation of conventional separation processes that involve liquid boiling in a micro-chemical system. However, membrane separations offer a feasible alternative for exploring the advantages of liquid phase separation in micro-chemical systems. The main objective of this research was to evaluate the process intensification effects in a microscale pervaporation process with experiments involving the separation of ethanol/water using a commercially available polymer dehydration membrane.

The microchannels in the microseparator were fabricated by the dry etch process at Louisiana Tech University. Microchannel depths of 20 to 120 μm, with …

Microparticulate Drug Reformulation Using Electrostatic Layer -By -Layer Assembly And Co-Entrapment With Anionic Phospholipids In Calcium Carbonate Matrix, Krishna Gopal

Doctoral Dissertations

Non-invasive drug delivery systems for therapeutic drugs are gaining prominence. One such system, the nasal delivery system, shows good prospect for effective delivery of some drugs, however, it is yet to be well established for others. The preparation of a reformulated drug and studying its in vitro characteristics is a crucial step in the process of adapting the new drug for nasal delivery systems. The purpose of this research is to study the effect of electrostatic layer by layer assembly of polyelectrolytes on PROMAXX®insulin microparticles and to study the chemical, physical and corresponding release properties of the resulting formulations. PROMAXX® …

Fluorescent Enzymatic Smart Tattoos Comprising Hybrid Silicate Microparticles, Metalloporphyrin Complexes, And Mass Transport-Limiting Nanofilms, Erich Wayne Stein

Doctoral Dissertations

Diabetics are often required to self-monitor blood glucose levels to effectively deliver prescribed therapies. However, the pain and bother associated with traditional finger-prick measurements often result in decreased patient compliance and therefore poor disease management, which could result in the early-onset of complications. Enzymatic "smart tattoos"—implantable luminescent particles that may be transdermally interrogated with light—are being pursued as minimally-invasive diabetic monitoring devices, with hopes of increasing diabetic compliance by reducing excessive pain and bother associated with finger-prick measurements. These devices typically comprise an oxygen-quenched luminescent dye and glucose oxidase (GOx), an enzyme that catalyzes the oxidation of β-D-glucose. Under glucose-limited …

Design And Development Of Triangular, Spiral, And Fractal Antennas For Radio Frequency Identification Tags, Jeevan K. Vemagiri

Doctoral Dissertations

This dissertation reports on the design and development of three compact, non-meandered microstrip patch antennas for ultra high frequency (UHF) radio frequency identification (RFID) applications. The monopole antennas considered in this work are an inset-fed triangular antenna, one arm Archimedes spiral antenna and a Half-Sierpinski fractal antenna. These antennas with small length to width ratios (< 2/1), can be the preferred choice, in the tagging of small size consumer end products, over the ubiquitous meandered dipole antenna (length/width > 5/1), which is often the antenna of choice, due to its high gain for UHF RFID applications. The lengths and widths of all three antennas are less than 5.5 cm. Earlier reports of planar antennas for RFID applications in the UHF range have lengths …

Molecular Modeling Of Proteins And Peptides Related To Cell Attachment In Vivo And In Vitro, Wanhua Zhao

Doctoral Dissertations

Polypeptides constitute half of the dry mass of the cell, they form the bulk of the extracellular matrix (ECM), and they are a common element of extra- and intracellular signaling pathways. There is increasing interest in the development of computational methods in polypeptide and protein engineering on all length scales. This research concerns the development of computational methods for study of polypeptide interactions related to cell attachment in vivo and in vitro.

Polypeptides are inherently biocompatible, and an astronomical range of unique sequences can be designed and realized in massive quantities by modern methods of synthesis and purification. These …

Stochastic Propagation Modeling And Early Detection Of Malicious Mobile Code, Xin Xu

Doctoral Dissertations

Epidemic models are commonly used to model the propagation of malicious mobile code like a computer virus or a worm. In this dissertation, we introduce stochastic techniques to describe the propagation behavior of malicious mobile code. We propose a stochastic infection-immunization (INIM) model based on the standard Susceptible-Infected-Removed (SIR) epidemic model, and we get an explicit solution of this model using probability generating function (pgf.). Our experiments simulate the propagation of malicious mobile code with immunization. The simulation results match the theoretical results of the model, which indicates that it is reliable to use INIM model to predict the propagation …

Sleep Quality Of College Students And Its Relationship To Coping Styles And Well-Being, Cathy Alison Word

Doctoral Dissertations

College students suffer from more sleep disturbances than the general population. Sleep difficulties in college students can lead to lower levels of performance, memory, and cognitive ability, as well as increased levels of anxiety and decreased levels of well-being. Sleep quality is known to impact individuals' physical and psychological health, which are indicators of well-being. Sleep also appears to influence individuals' choices of coping strategies. Sleep quality is also highly correlated with college students' emotional response to stress. The relationships between and among sleep quality, well-being, and coping style have not been fully examined. The purpose of this study was …

Delay Line Based Passive Radio Frequency Identification Tags, Aravind Chamarti

Doctoral Dissertations

This work describes the concept, design, fabrication, and characterization of delay-based radio frequency identification (RFID) tags and RFID-based sensor tags, representing a novel RFID technology. The presented delay-based RFID concept is based on the LC-delay-line and transmission-delay-line based approaches. The proposed concept allows the realization of RFIDs and RFID-based sensor tags at any allowed radio frequency, with the limitation of realizing delay elements capable of producing required delays. The RFID configurations presented in this work are for operation at 915 MHz. Simulations are used to design and optimize components and devices that constitute the tags, and to integrate them to …

A Novel Computational Framework For Fast, Distributed Computing And Knowledge Integration For Microarray Gene Expression Data Analysis, Prerna Sethi

Doctoral Dissertations

The healthcare burden and suffering due to life-threatening diseases such as cancer would be significantly reduced by the design and refinement of computational interpretation of micro-molecular data collected by bioinformaticians. Rapid technological advancements in the field of microarray analysis, an important component in the design of in-silico molecular medicine methods, have generated enormous amounts of such data, a trend that has been increasing exponentially over the last few years. However, the analysis and handling of these data has become one of the major bottlenecks in the utilization of the technology. The rate of collection of these data has far surpassed …

Multicomponent Patterning Of Nanocomposite Polymer And Nanoparticle Films Using Photolithography And Layer-By-Layer Self -Assembly, Javeed Shaikh Mohammed

Doctoral Dissertations

In this dissertation, the fabrication, characterization, and application examples of 3D multicomponent nanocomposite micropatterns (MNMs) with precise spatial arrangements are described. The ability to produce such small-scale 3D structures with versatility in composition and structure is a new development based on the integration of nanoscale layer-by-layer (LbL) self-assembly and microscale photolithographic patterning, enabling construction of surfaces with microscale patterns that possess nanotopographies. The techniques used here are analogous to surface micromachining, except that the deposition materials are polymers, biological materials, and colloidal nanoparticles used to produce 3D MNMs. A key feature of the resulting 3D MNMs is that the physical …

Modeling And Simulation Of Value -At -Risk In The Financial Market Area, Xiangyin Zheng

Doctoral Dissertations

Value-at-Risk (VaR) is a statistical approach to measure market risk. It is widely used by banks, securities firms, commodity and energy merchants, and other trading organizations. The main focus of this research is measuring and analyzing market risk by modeling and simulation of Value-at-Risk for portfolios in the financial market area. The objectives are (1) predicting possible future loss for a financial portfolio from VaR measurement, and (2) identifying how the distributions of the risk factors affect the distribution of the portfolio. Results from (1) and (2) provide valuable information for portfolio optimization and risk management.

The model systems chosen …

Three Essays On Banking And Corporate Finance, Fang Zhao

Doctoral Dissertations

This dissertation is composed of three essays on banking and corporate finance. The first essay studies the relationship between interest-rate derivative usage and bank lending. Using recent data that cover a full business cycle, this paper documents a direct relationship between interest-rate derivative usage by U.S. banks and growth in their commercial and industrial (C&I) loan portfolios. This positive association holds for interest-rate options contracts, forward contracts, and futures contracts. This result is consistent with the implication of Diamond's model (1984) that predicts that a bank's use of derivatives permits better management of systematic risk exposure, thereby lowering the cost …

Development Of Self-Assembled Monolayer-Based Cell Culture Platform Towards Fabrication Of A Three-Dimensional Bioreactor, Rajendra Kandoor Aithal

Doctoral Dissertations

The extracellular matrix (ECM) plays an important role in regulating a number of cellular properties and functions like cell differentiation, cell synthesis and degradation, cell viability and proliferation, cell function, and cell aging. Surface modification of planar substrates with self-assembled monolayers (SAMs) is a promising technique to achieve stable ECMs.

In this work, substrates such as silicon (Si), gallium arsenide (GaAs) and indium tin oxide (ITO) substrates were modified with SAMS containing amino (-NH2), methyl (-CH3), thiol (-SH) and carboxylic (-COOH) end groups and characterized using contact angle measurements, surface infrared (IR) spectroscopy and atomic force microscopy (AFM). Different cell …

Development Of A High Spatial Selectivity Tri-Polar Concentric Ring Electrode For Laplacian Electroencephalography (Leeg) System, Kanthaiah Koka

Doctoral Dissertations

Brain activity generates electrical potentials that are spatio-temporal in nature. Electroencephalography (EEG) is the least costly and most widely used non-invasive technique for diagnosing many brain problems. It has high temporal resolution but lacks high spatial resolution.

The surface Laplacian will enhance the spatial resolution of EEG as it performs the second spatial derivative of the surface potentials. In an attempt to increase the spatial selectivity, researchers introduced a bipolar electrode configuration using a five point finite difference method (FPM) and others applied a quasi-bipolar (tri-polar with two elements shorted) concentric electrode configuration. To further increase the spatial resolution, the …

A Numerical Method For Obtaining An Optimal Temperature Distribution In A Three-Dimensional Triple-Layered Skin Structure Embedded With Multi-Level Blood Vessels, Xingui Tang

Doctoral Dissertations

The research related to hyperthermia has stimulated a lot of interest in recent years because of its application in cancer treatment. When heating the tumor tissue, the crucial problem is keeping the temperature of the surrounding normal tissue below a certain threshold in order to avoid the damage to the normal tissue. Hence, it is important to obtain the temperature field of the entire region during the treatment. The objective of this dissertation is to develop a numerical method for obtaining an optimal temperature distribution in a 3D triple-layered skin structure embedded with multi-level blood vessels where the surface of …

Measuring Inequality: Statistical Inference Theory With Applications, Mihaela Paun

Doctoral Dissertations

In this dissertation we develop statistical inference for the Atkinson index, one of the measures of inequality used in studying economic inequality.

Specifically, we construct empirical estimators for the Atkinson index, both in the parametric and nonparametric case, and derive formulas for the asymptotic variances for the estimators. These statistics are used for testing hypothesis and constructing confidence intervals for the Atkinson index. We test the validity and the robustness of the asymptotic theory, by simulations (using R, a language and environment for statistical computing and graphics), in the case of one and two populations. In addition to proving asymptotic …

Development And Applications Of Inkjet Printed Conducting Polymer Micro-Rings, Rajneek K. Khillan

Doctoral Dissertations

A drying sessile drop moves the solute particles to the periphery where they get deposited in the form of a ring. This phenomenon is prevalent even with micro drops falling at high velocity from a piezo-actuator based inkjet printer. In polymer microelectronic field, this phenomenon is a major challenge for fabricating devices using inkjet printing. We exploited this problem and applied it for various novel applications in the field of polymer microelectronics.

Various dispensing techniques and temperature variations for micro-drop printing were used for modifying the micro-drops in such a way that the periphery of the micro-ring holds most of …