Digital Commons Network^™

Magnetohydrodynamic Power Generation In A Scramjet Using A Post Combustor Generator, Nathan Lee Mundis

Masters Theses

"A scramjet with a post combustor MHD generator is examined. A quasi-one-dimensional model is developed to calculate the flow path from tip to tail. The model includes losses due to combustion irreversibility, incomplete combustion, chemically reacting flow, friction, MHD losses, and nozzle plume modeling. Flight Mach number, magnetic field strength, gas conductivity, MHD load factor, and MHD generator expansion angle are all varied in order to assess their effects on MHD power generated and thrust lost in the engine. The trends produced through the above variations are summarized in a set of model-fit equations. It is concluded that a post …

Cfd Simulation Of Contact Planarization, Shanti Vusirikala

Masters Theses

"Semiconductor devices form the essential components of most electronic devices. The fabrication of circuit elements to manufacture these devices is done by a process known as photolithography, using photoresist layer deposition, optical masks, and etching. As feature sizes become smaller, higher optical precision is required, necessitating an optically flat surface on the photoresist layer. The surface of the photoresist layer can become uneven because of conformation to the topography of the layers underneath or a change in shape of the layer after evaporation of solvent. To combat this, Brewer Science, Inc. has developed a contact planarization process (CON-TACT®) in which …

Device Signal Detection Methods And Time Frequency Analysis, Narayana Ravirala

Masters Theses

"In this thesis the application of independent component analysis (ICA) to a multiple-source detection problem is studied. Specifically, a detection problem that is somewhat of a blend of the classical "signals with unknown parameters in noise" and "random signals in noise" problems is investigated. The idea is to detect the presence of a class of devices from their unintended radio frequency (RF) radiation. Because the signal is not an intended radiation, each device will emit a slightly different pattern. Moreover, these patterns may change under varying conditions such as battery voltage and ambient temperature. In addition, there may be several …

Modeling And Performance Estimation For Airborne Minefield Detection System, Saurabh Agarwal

Masters Theses

"Many programs aimed at airborne mine and minefield detection are being pursued and different algorithms are being developed and evaluated to achieve performance specifications. Thus far, no single algorithm or detection architecture has been able to fulfill the performance specifications for different mine and minefield detection scenarios...a need exists for a simulation based approach. One such simulation system is developed and evaluated in this thesis. The factors affecting the performance of an airborne detection system include physical parameters (type of background, time of day), data collection parameters (swath width, number of steps, in-step and in-flight overlap), and minefield scenarios. Data …

Compressor Valve Failure Detection And Prognostics, Raghuram Puthali Ramesh

Masters Theses

"Reciprocating compressors are commonly used machinery for industrial applications. Unscheduled downtime and maintenance activity on the compressors causes considerable loss in throughput and efficiency of a plant. Of all the failures that cause unscheduled downtime in reciprocating compressors, valve related causes are predominant. Most of the failures associated with the valves are tracked to the failure of moving elements within the valve. Achieving higher reliability of critical reciprocating systems requires continuously monitoring the system and performing dynamic analysis of the sensory data for valve fault diagnosis. Continuous monitoring will improve the time and cost to repair through keeping a constant …

Adhesion-Delamination Mechanics Of Linear And Axisymmetric Film At Film-Substrate Interface, Ming-Fung Wong

Masters Theses

"This thesis is to characterize the thin membrane adhesion-delamination phenomena which occur in biological cells and micro-electro-mechanical systems (MEMS) operation. The delamination of a thin film adhered to a rigid substrate is subjected to the coupling effects of tensile residual stress and interfacial adhesion energy. The adhesion-delamination mechanics is derived using the classical linear elasticity and thermodynamics energy balance. The membrane deformation is here dominated by a mixed plate-bending and membrane-stretching, while the concomitant stress is neglected. An 1-dimensional model is first investigated where a pre-stressed rectangular film clamped at both ends delaminates from a rigid punch of the same …

Ph Effect On Adsorption Of Saxititoxin On Powdered Activated Carbon, Jie Ding

Masters Theses

"The presence of algal toxins, or cyanotoxins, in surface water has been increasingly reported. These highly hazardous toxins are potential threat to both human health and animals by contaminating drinking water sources over the world. In this study, the removal efficiency of saxitoxin from water using powered activated carbon was tested at different pH values for deionized water and natural surface water. The results of this study showed that pH has a strong impact on removal efficiency of saxitoxin using powdered activated carbon. Specifically, the removal efficiency of saxitoxin is significantly increased at higher pH from 5.7 to pH 10.7. …

Data Fusion Techniques For Health Monitoring Of Aging Aircraft And Skin Cancer Detection, Kapil Gupta

Doctoral Dissertations

"Data fusion is generally practiced to enhance decision or inference making capability. Sensor and information source data may often be corrupted by noise or other factors. Data fusion can be used to improve sensor and/or information source data quality and reliability and improve detection accuracy. There are several types of data fusion, including raw data level, feature level, and decision level.

This work presents the investigation and development of image and signal processing, computational intelligence, fuzzy logic, and statistical techniques for different types of data fusion for a varied range of applications. Raw data and decision level fusion approaches are …

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 …

Quantum Dot Photolithography, Raghuveer Reddy Gadipalli

Doctoral Dissertations

"This dissertation presents a simple method for the photolithographic patterning of silica hydrogel monoliths and planar substrates with quantum dots and inorganic semiconductor nanoparticles. We developed a method for surface patterning and bulk (3D) patterning of silica hydrogel monoliths and surface patterning of planar substrates with CdS, CdSe, PbS and PbSe quantum dots using infrared light, ultraviolet light, X-rays, and multi-photon ionization radiation. Precursor combinations were prepared which can readily dissociate with IR, UV, X-rays, and multi-photon ionization radiation. Different capping agents were used for improving quantum dot size distribution. The luminescence quantum yield of the composites can be increased …

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.

Development Of A Geographic Information System-Based Virtual Geotechnical Database And Assessment Of Liquefaction Potential For The St. Louis Metropolitan Area, Jae-Won Chung

Doctoral Dissertations

"The St. Louis Metropolitan area is the focus the U.S. Geological Survey's Earthquake Hazard Program's plan for assessing and reducing the likely risks of an earthquake likely emanating from New Madrid Seismic Zone (NMSZ), which is the most active seismic zone in the Midwestern United States. The St. Louis Metropolitan area consists of three counties in Missouri and four in Illinois, which are divided by the state boundary along the Mississippi River. Both of the state's respective geological surveys have produced their own geologic maps and datasets, employing dissimilar geodata information and systems, with differing map units, map scales, and …

Architecting System Of Systems: Artificial Life Analysis Of Financial Market Behavior, Nil Hande Ergin

Doctoral Dissertations

"This research study focuses on developing a framework that can be utilized by system architects to understand the emergent behavior of system architectures. The objective is to design a framework that is modular and flexible in providing different ways of modeling sub-systems of System of Systems. At the same time, the framework should capture the adaptive behavior of the system since evolution is one of the key characteristics of System of Systems. Another objective is to design the framework so that humans can be incorporated into the analysis. The framework should help system architects understand the behavior as well as …

An Investigation Of Lead And Other Metal Contaminants In The Sediments Of Clearwater Lake, Missouri, Gary W. Krizanich

Doctoral Dissertations

"The purpose of this investigation is to characterize the spatial and temporal distribution and concentration of trace metals in sediments of Clearwater Lake. Understanding how trace metals are released to and transported in aquatic environments is important to the overall understanding of the impacts of mining on the natural environment. The main focus of this research will be on historic sedimentation within Clearwater Lake, which may act as a sink where mining related trace metals are stored. Because of their high preservation rates in basins, sediments can provide detailed chronostratigraphic histories of trace metal inputs in lakes. Sediment records can …

Simple And Efficient Solutions To The Problems Associated With Acoustic Echo Cancellation, Asif Iqbal Mohammad

Doctoral Dissertations

"This dissertation is a collection of papers that addresses several important problems associated with acoustic/line echo cancellation (AEC/LEC), specifically double-talk and echo-path change detection. A double-talk detector is used to freeze AEC filter's adaptation during periods of near-end speech. This dissertation presents three different novel double-talk detection schemes. Simulations demonstrate the efficiency of the proposed algorithms"--Abstract, page iii.

Pilot Program To Assess Seismic Hazards Of The Granite City, Monks Mound, And Columbia Bottom Quadrangles, St. Louis Metropolitan Area, Missouri And Illinois, Deniz Karadeniz

Doctoral Dissertations

"Three 1:24000 scale quadrangles were selected for a pilot program intended to evaluate seismic site response across the spectrum of geologic conditions underlying the St. Louis Metropolitan area, using the Granite City, Monks Mound and Columbia Bottom quadrangles. These evaluations included assessments of: i) site amplification distributions; ii) probabilistic hazard analysis of PGA, 0.2 second and 1.0 second spectral accelerations for 2%, 5% and 10% probability of exceedance in 50 years; iii) two scenario earthquakes and their associated PGA, 0.2 sec, and 1 sec spectral accelerations; and v) sensitivity and uncertainty analyses. These hazard maps were prepared using a fully-probabilistic …

An Indirect Loss Estimation Methodology To Account For Regional Earthquake Damage To Highway Bridges, Chakkaphan Tirasirichai

Doctoral Dissertations

"This study proposes an integrated framework to estimate the indirect economic loss due to damaged bridges within the highway system from an earthquake event. The framework is designed to be general and convenient to apply to other study regions. In this dissertation, a simulated earthquake scenario centered in St. Louis Missouri with a magnitude 7.0 was used as a case study. The research results have clearly shown that the indirect losses are significant when compared to the direct loss. Policymakers can apply this study framework and the results as a guide and decision tool for developing an appropriate preventive action …

Modeling Network Traffic On A Global Network-Centric System With Artificial Neural Networks, Douglas K. Swift

Doctoral Dissertations

"This dissertation proposes a new methodology for modeling and predicting network traffic. It features an adaptive architecture based on artificial neural networks and is especially suited for large-scale, global, network-centric systems. Accurate characterization and prediction of network traffic is essential for network resource sizing and real-time network traffic management. As networks continue to increase in size and complexity, the task has become increasingly difficult and current methodology is not sufficiently adaptable or scaleable. Current methods model network traffic with express mathematical equations which are not easily maintained or adjusted. The accuracy of these models is based on detailed characterization of …

Detection Algorithms For Spatial Data, Spandan Tiwari

Doctoral Dissertations

"This dissertation addresses the problem of anomaly detection in spatial data. The problem of landmine detection in airborne spatial data is chosen as the specific detection scenario. The first part of the dissertation deals with the development of a fast algorithm for kernel-based non-linear anomaly detection in the airborne spatial data. The original Kernel RX algorithm, proposed by Kwon et al. [2005a], suffers from the problem of high computational complexity, and has seen limited application. With the aim to reduce the computational complexity, a reformulated version of the Kernel RX, termed the Spatially Weighted Kernel RX (SW-KRX), is presented. It …

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.

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.

Synthetic Methods For Biologically Relevant Organofluorine Compounds, Meher Perambuduru

Doctoral Dissertations

"This thesis describes novel synthetic methodologies for the synthesis of biologically relevant organofluorine compounds"--Abstract, page iii.

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.

Impacts Of Acid Mine Drainage On Carbon Cycling In Receiving Streams, Ernest W. Fonyuy

Doctoral Dissertations

"Field and laboratory investigations of acid mine drainage (AMD) contaminated and uncontaminated waters were conducted in order to determine and model processes and reaction mechanisms that control dissolved inorganic carbon (DIC) transformation and shifts in isotope ratio of DIC (Δ¹³C_DIC). The results show that AMD caused variable pH changes, overall decreases in Fe²⁺, alkalinity, and DIC, and increases in (Δ¹³C_DIC) in receiving streams. AMD caused more than 50 to > 98% seasonal DIC loss in stream water through CO₂ degassing. High DIC losses corresponded to high Fe²⁺ and lower or no HCO₃⁻ in the water samples, because …

Marvin S. Pittman: A Historical Inquiry Of His Life, Legacy And Leadership, Pamela Frost Altman

College of Graduate Studies: Theses & Dissertations

This dissertation is an inquiry into the educational leadership style of Marvin Summers Pittman, April 12, 1882-February 27, 1954. Pittman was a transformational leader with a vision to set goals that sometimes appeared to be outside the box during his time as an educational leader. Pittman introduced new and innovative programs in education, including his zone plan for teacher training, and theories for the consolidation of schools. Pittman understood that education was the tool needed to give power back to the people, and to enable them to be productive citizens. Education was Pittman's tool to bring the poor farm boy …

Grade Inflation: An Analysis Of Teacher Perception, Grade Point Average, And Test Scores In One Southeastern Georgia High School, Aimée Claire Taylor

College of Graduate Studies: Theses & Dissertations

The following case study examined the existence of grade inflation at one high school in southeastern Georgia, South High School. This mixed methodology research study examined grade inflation from two major perspectives, student data and teacher data; thus, creating a quantitative and qualitative research study. Triangulation in data collection was used to gather information about 160 seniors and 76 classroom teachers, which offered greater insight into evidence and perceptions of grade inflation. The standardized test scores of students and their GPAs were correlated to determine the extent of the relationship between GPAs and SAT scores and between GPAs and End …

Georgia Southern Magazine, Georgia Southern University

Georgia Southern Magazine

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Georgia Southern Magazine, Georgia Southern University

Georgia Southern Magazine

• Campus News
• Research News
• Foundation News
• Sports Scene
• Centennial Celebrations
• Excellence Marks Their Spot
• Chronicles