Digital Commons Network^™

Characterization Of Hfo2 Films For Flash Memory Applications, Surendra Gaddipati

USF Tampa Graduate Theses and Dissertations

The scaling of integrated circuits requires the use of alternative dielectric materials as the replacement for silicon dioxide in the submicron devices. The scaling limit for silicon dioxide used in MOSFETs is 1.2nm and the Oxide Nitride Oxide (ONO) stack used in flash memory applications is 13.0nm. The use of alternative dielectrics with high- κ value will alleviate the problem of charge retention and also would help to decrease the programming voltage in case of flash memory cells.

Many alternative high- κ dielectric materials such as TaO₂, TiO₂, Al₂O₃ etc., have been examined …

Cadmium Zinc Telluride Solar Cells By Close Spaced Sublimation, Madhan Raj Ramalingam

USF Tampa Graduate Theses and Dissertations

Cadmium Zinc Telluride (Cd_xZn_1-xTe or CZT) is a ternary semiconductor with a tunable bandgap of 1.44-2.26 eV. Solar cells with efficiencies of 20% or higher can be achieved by using a tandem solar cell structure which consists of a top cell and a bottom cell connected in series. In this kind of a structure, the light passes through the top cell first which has a wider bandgap to absorb light of shorter wavelengths and the remaining light passes through the bottom cell with a lower bandgap to absorb light of higher wavelengths. For a tandem cell …

Improved 1/F Noise Measurements For Microwave Transistors, Clemente Toro Jr.

USF Tampa Graduate Theses and Dissertations

Minimizing electrical noise is an increasingly important topic. New systems and modulation techniques require a lower noise threshold. Therefore, the design of RF and microwave systems using low noise devices is a consideration that the circuit design engineer must take into account. Properly measuring noise for a given device is also vital for proper characterization and modeling of device noise. In the case of an oscillator, a vital part of a wireless receiver, the phase noise that it produces affects the overall noise of the system. Factors such as biasing, selectivity of the input and output networks, and selectivity of …

Recycled Materials Relational Database: Design And Implementation Aspects, Rory Morgan Mcdonald

USF Tampa Graduate Theses and Dissertations

Although there has been a rise in the use of recycled materials in highway and geotechnical systems, many tons of potentially useful industrial and domestic by-products are still being discarded in the United States each year. While extensive research has been conducted to investigate the use of recycled materials in engineering applications, the dissemination of the findings is often limited. The problem is compounded by the lack of a single resource containing relevant engineering and environmental characteristics of each material; the tendency of the researchers to publish their findings in technical reports rather than archived publications; and the wide discrepancies …

Small Drainage Basins And The Probable Maximum Flood: A Flood Inundation Study Of An Anticipated Extreme Storm Event In West Central Florida, Philip Anthony Ranalli

USF Tampa Graduate Theses and Dissertations

A major tropical storm will strike in the area of West Central Florida. In anticipation of this storm, this study seeks to predict the specific areas within the Baker Canal drainage basin that will be inundated as a result of this expected event. There are few references concerning extreme flooding in small drainage basins within existing literature.

For the purposes of this study this event was considered to be a Probable Maximum Flood (PMF) as defined by Crippen and Bue (1977). The Hydrologic Engineering Centers' Geographic River Analysis System was used to develop water surface elevations and flow rates. Maps …

Accuracy And Bias Of Tdr Measurements In Compacted Sands, Newel Kimball White

USF Tampa Graduate Theses and Dissertations

It is essential to properly monitor in-situ soil compaction properties during most earthwork construction projects. Traditional in-situ soil compaction monitoring methods are often limited in their application. As a result, new methods are being developed to more accurately measure in-situ compaction parameters. Time domain reflectometry (TDR) is one such method. Relying on the propagation of an electromagnetic wave through the soil sample, TDR can be used to measure both in-situ moisture content as well as soil dry density. Although TDR is relatively new to the field of geotechnical engineering, it has previously been implemented in other fields with success. Researchers …

Characterization Of Cadmium Zinc Telluride Solar Cells By Rf Sputtering, Senthilnathan Subramanian

USF Tampa Graduate Theses and Dissertations

High efficiency solar cells can be attained by the development of two junctions one stacked on top of each other into tandem structures. So that, if a photon is not able to excite an electron-hole pair in the top cell can create a pair in the bottom cell, which has a smaller bandgap. For a two junction tandem device structure, the bandgap of the top cell should be 1.6-1.8eV and for the bottom cell should be 1eV to attain efficiencies in the range of 25%. Cadmium Zinc Telluride which has a tunable bandgap of 1.45- 2.2eV is a candidate for …

Processing And Characterization Of Cigs - Based Solar Cells, Venkatesh Mohanakrishnaswamy

USF Tampa Graduate Theses and Dissertations

The goal of this research was to understand the role of the glass substrate and molybdenum (Mo) back contact on the performance of Copper Indium Gallium diselenide (CIGS) / Cadmium Sulphide (CdS) based photovoltaic devices, and to improve the performance of these devices.

The CIGS absorber layer was fabricated in a 2 stage process. In this process the metal precursors were deposited at 275^oC followed by a high temperature selenization step. The advantage of the 2 stage process is that it is manufacturing friendly.

The first step in fabrication of solar cells is to clean the substrate which …

Design Of A Chemical Agent Detector Based On Polymer Coated Surface Acoustic Wave (Saw) Resonator Technology, Lane Leslie Manoosingh

USF Tampa Graduate Theses and Dissertations

This dissertation presents the design of a unique prototype chemical agent detector which utilizes an array of polymer coated SAW resonators as the sensor elements. The design's particular embodiment is that of a testing platform for evaluating the utility of constructing a portable chemical agent detector, utilizing commercially available SAW resonators. It involves the consolidation of the sub-systems comprising a large laboratory development system, into a portable enclosure.

A combination of design techniques, utilized to achieve an overall balance between the physical dimensions of the system and its detection performance, comprises the unique nature of the overall design of this …

Hydraulic, Diffusion, And Retention Characteristics Of Inorganic Chemicals In Bentonite, Naim Muhammad

USF Tampa Graduate Theses and Dissertations

Inorganic contaminants, while transported through the bentonite layer, are chemically adsorbed onto the particle surfaces and exhibit a delay in solute breakthrough in hydraulic barriers. Transport of inorganic leachate contaminants through bentonite occurs by advection, diffusion or a combination of these two mechanisms. During the process of chemical solute transport through low permeability bentonite, the amount of cation exchange on the clay particle surface is directly related to the cation exchange capacity (CEC) of montmorillonite and other mineral constituents.

The process of diffusion and advection of various inorganic leachate contaminants through bentonite is thoroughly investigated in this study. Diffusion characteristics …

Inner-Shelf Bottom Boundary Layer Development And Sediment Suspension During Tropical Storm Isadore On The West Florida Shelf., Justin G. Brodersen

USF Tampa Graduate Theses and Dissertations

Observations of the bottom boundary layer on the inner West Florida Shelf were made with a downward looking pulse coherent acoustic Doppler profiler throughout the passage of Tropical Storm Isadore during September 2002. The storm passed through the Gulf of Mexico roughly 780 km offshore of the Florida study site. Significant wave heights ranged from 0 m to 2.5 m within a span of eight days. The excellent, non-invasive, 5 cm resolution of the near bed (bottom meter) mean flows were used to estimate bed shear velocity and bottom roughness using the standard log-layer approach. A unique opportunity to examine …

Fuzzy Ants As A Clustering Concept, Parag M. Kanade

USF Tampa Graduate Theses and Dissertations

We present two Swarm Intelligence based approaches for data clustering. The first algorithm, Fuzzy Ants, presented in this thesis clusters data without the initial knowledge of the number of clusters. It is a two stage algorithm. In the first stage the ants cluster data to initially create raw clusters which are refined using the Fuzzy C Means algorithm. Initially, the ants move the individual objects to form heaps. The centroids of these heaps are redefined by the Fuzzy C Means algorithm. In the second stage the objects obtained from the Fuzzy C Means algorithm are hardened according to the …

Vapor Cdcl2 Processing Of Cdte Solar Cells, Mursheda Hussain

USF Tampa Graduate Theses and Dissertations

Polycrystalline CdS/CdTe thin film solar cells are among the leading candidates for low-cost, large scale terrestrial photovoltaic applications. CdTe has a high absorption coefficient and it can absorb the radiant energy within less than 2 µm of thickness. This makes it suitable for thin film applications. CdTe has a band gap of 1.45 eV at room temperature, which is nearly optimum for photovoltaic conversion efficiency under the AM 1.5 solar spectrum. The theoretical maximum efficiency for CdTe solar cells is 29%. However, to-date the experimental value is in the 16 % range.

In most cases CdTe cells are subjected to …

Co-Production Of Hydrogen And Sulfuric Acid By Electrolysis, Maheshkumar Chettiar

USF Tampa Graduate Theses and Dissertations

Hydrogen gas is the cleanest fuel which produces only water as a combustion product with no greenhouse or toxic gases. The combustible hydrogen fuel is an energy carrier but not an energy source. As an element, hydrogen is widely available in nature as a component of water and of hydrocarbons. An energy source is needed to extract the element from these compounds and convert it to the combustible hydrogen gas.

Today, the energy source for nearly all hydrogen production is fossil fuel, principally natural gas. The supply of natural gas is limited and its price is increasing. Greenhouse gas and …

Fabrication Of Cigs Absorber Layers Using A Two-Step Process For Thin Film Solar Cell Applications, Harish Sankaranarayanan

USF Tampa Graduate Theses and Dissertations

Copper Indium Gallium DiSelenide absorber layers are fabricated using a two step manufacturing-friendly process. The first step involves the sequential deposition of Copper and Gallium and codeposition of Indium and Selenium, not necessarily in that order, at 275^o C. This is followed by the second stage, where the substrate is annealed in the presence of Selenium and a thin layer of Copper is deposited to neutralize the excess Indium and Gallium on the surface to form the Copper Indium Gallium diSelenide absorber layer. Elimination of the need for high degree of control and elimination of toxic gases like hydrogen …

Estimation Of Switching Activity In Sequential Circuits Using Dynamic Bayesian Networks, Karthikeyan Lingasubramanian

USF Tampa Graduate Theses and Dissertations

This thesis presents a novel, non-simulative, probabilistic model for switching activity in sequential circuits, capturing both spatio-temporal correlations at internal nodes and higher order temporal correlations due to feedback. Switching activity, one of the key components in dynamic power dissipation, is dependent on input streams and exhibits spatio-temporal correlation amongst the signals. One can handle dependency modeling of switching activity in a combinational circuit by Bayesian Networks [2] that encapsulates the underlying joint probability distribution function exactly.

We present the underlying switching model of a sequential circuit as the time coupled logic induced directed acyclic graph (TC-LiDAG), that can be …

Globalization: The Relationship Between The State And The Economy, Michael Mena

USF Tampa Graduate Theses and Dissertations

Many people agree that we live in a changing world. It is a world transformed by globalization. I propose that changes in state policies have led to a change from an international economy to a global economy, thereby contributing to the emergence of contemporary globalization. Changes in state power/authority and policies have affected the overall economy. These changes have caused the economy to transform from a national economy to a global economy.

I test the hypothesis through a case study of Guatemala's Economy. The time period for this study is from 1982 to 2002. The economy of Guatemala is comprised …

Total Evaporative Resistance Of Selected Clothing Ensembles, Victor Caravello

USF Tampa Graduate Theses and Dissertations

With regard to heat stress, the limiting factor inherent in clothing ensembles is the total evaporative resistance. Clothing with higher evaporative resistance impedes the ability to cool by sweat evaporation. Knowing the evaporative resistance provides a means to compare candidate ensembles. Further, a value for evaporative resistance means that a rational method can be used to assess the heat stress exposure. Evaporative resistance of five clothing ensembles (cotton work clothes, cotton coveralls, and three coveralls of particle barrier, liquid barrier and vapor barrier properties) was determined empirically from wear tests during two study phases. For Phase 1, the metabolic rate …

A Comparison Of Weekend And Weekday Travel Behavior Characteristics In Urban Areas, Ashish Agarwal

USF Tampa Graduate Theses and Dissertations

Travel demand analysis has traditionally focused on exploring and modeling travel behavior on weekdays. This emphasis on weekday travel behavior analysis was largely motivated by the presence of well-defined peak periods, primarily associated with the journey to and from work. Most travel demand models are based on weekday travel characteristics and purport to estimate traffic volumes for daily or peak weekday conditions. Much of the planning and policy making that occurs in transportation arena in response to weekday travel behavior and forecasts.

More recently, there had been a growing interest in exploring, understanding, and quantifying weekend travel characteristics. The ability …

The Effects Of Computer Simulation And Learning Styles On Emergency Vehicle Drivers’ Competency In Training Course, Jeffrey T. Lindsey

USF Tampa Graduate Theses and Dissertations

The number of accidents over the past decade involving emergency vehicles is a major concern for emergency service providers. This study assessed the effectiveness of adding a driving simulator to a traditional training program. Potential relationships with students' learning styles using Gregorc Mind Style Delineator were also examined.

The general research design consisted of a quantitative portion (quasi-experimental) and a qualitative portion (phenomenological). The sample population consisted of Emergency Medical Technician students attending the National EMS Academy in Lafayette, LA. The didactic session was conducted first with 102 participants in attendance. The driving portion was conducted over five days. The …

Design, Fabrication And Characterization Of Thin-Film M-I-M Diodes For Rectenna Array, Subramanian Krishnan

USF Tampa Graduate Theses and Dissertations

A Metal-Insulator-Metal (MIM) diode is a high frequency device used for energy harvesting purpose in the RECTENNA. The main objective of this thesis work is to design, fabricate and characterize a thin-film MIM diode. A key issue associated in this research work is the development MIM diode with nanometer thin insulator region. The reason for the development of MIM diode is to rectify a wide spectrum of AC signal to usable DC power. In this thesis work, a planar MIM diode with Aluminum/Aluminum-Oxide/Gold has been fabricated. The thickness of the insulator region obtained was about 3nm. The Metal and insulator …

What Faculty Know About Designing Online Materials In Compliance With Current U.S. Copyright And Fair Use Laws, Phyllis C. Sweeney

USF Tampa Graduate Theses and Dissertations

Digital technology has vastly increased the ability of individuals to copy, produce and distribute information, making the behavior of individuals a far more significant factor in the enforcement of copyright and fair use laws than in the past. This research investigates the resources used by university faculty and their knowledge of fair use regarding web-based course materials. Specifically, the research A) identifies prevailing trends in faculty use of resource materials in the development of web-based courses including digital images, text, video and sound; B) determines how faculty members have gained and applied their fair use knowledge; and C) interprets any …

The Depositional History Of Three Freshwater Lakes In North Central Florida: Brooklyn Lake, Levys Prairie, And Cowpen Lake, Nancy T. Dewitt

USF Tampa Graduate Theses and Dissertations

Florida has approximately 7800 lakes that are heavily concentrated in the north-central part of the state—a mantled karst terrain. Although much research has been conducted in Florida’s lakes, there is not much information on the sedimentary infill. The focus of this research is to define the sedimentary infill of three closely spaced lakes (Brooklyn Lake, Levys Prairie, and Cowpen Lake) in north-central Florida and determine the relative importance of the various
sedimentary inputs and their associated processes. Interlake lithostratigraphy comparison helped determine if they experienced a similar depositional infilling history or a unique one.

Twenty-three vibracores were taken (12 in …

A Comparative Study Of Artificial Neural Networks And Info Fuzzy Networks On Their Use In Software Testing, Deepam Agarwal

USF Tampa Graduate Theses and Dissertations

It is very important that the software being delivered to the user is reliable and fault free. This makes software testing one of the most important phases in the software development life cycle. The problem being faced by everyone is the time it takes to test the software, which is normally huge. An important part of the software testing process is running and evaluating test scenarios. The objective of this part is to evaluate how well the application under test conforms to its specifications. One of the ways to achieve this is to generate the test cases and make use …

A Wavelet Based Multiscale Run-By-Run Controller For Multiple Input Multiple Output (Mimo) Processes, Santosh Kothamasu

USF Tampa Graduate Theses and Dissertations

Run-by-Run (RbR) control is an online supervisory control strategy designed for the batch manufacturing industry. The objective of RbR control is to minimize process drift, shift and variability between machine runs, thereby reducing costs. The most widely used RbR controllers use the Exponentially Weighted Moving Average (EWMA) filter. However, the linear nature of the EWMA filter makes these RbR controllers inefficient for processes with features at multiple frequencies (also known as multiscale processes). Recent developments in wavelet theory have enhanced the ability to analyze events in multiscale processes. New RbR control strategies have started to emerge that incorporate wavelet analysis. …

Preparation And Characterization Of Ribonucleic Acid (Rna)/Inorganic Materials Interfaces Using Photoemission Spectroscopy, Brian, Doran

USF Tampa Graduate Theses and Dissertations

The objective of this master s thesis is the preparation and characterization of ribonucleic acid (RNA)/inorganic material interfaces by electrospray deposition and photoemission spectroscopy. This was done through investigation of the chemical and electronic structure of the surface of Highly Ordered Pyrolytic Graphite (HOPG) and gold before and after multiple steps of RNA thin film deposition by electrospray. Great interest has been shown by researchers into RNA due to its self-assembling ability. A series of experiments was conducted depositing RNA Poly adenosine, RNA Poly cytidine, and (for control purposes) DI water on HOPG. RNA Poly adenosine was also deposited on …

Time Course Of Perceptual Grouping In User Interface Displays, Melissa F. Schulz

USF Tampa Graduate Theses and Dissertations

Perceptual grouping describes the organization of small elements into larger objects. Research in user interface (UI) design has demonstrated effects of perceptual grouping on attention and navigation. However, grouping can be mediated by a variety of task factors. One such mediator is processing time. Recent discoveries in vision science suggest that elemental grouping can occur in more than one way, depending on how long elements are displayed. These findings have led to a new understanding of perceptual organization of elements in real-world spatial environments. However,these findings had not been explored within the context of UI environments. Time limits to UI …

Proposal For: “University Of South Florida Pinellas County Hearing And Speech Center – Usf-Pchsc”, Mary J. Francis B.A.

USF Tampa Graduate Theses and Dissertations

The University of South Florida Pinellas County Hearing and Speech Center (USF-PCHSC) is a nonprofit 501 (C) 3 organization that will offer comprehensive audiology and speech-language pathology services to people of all ages. USF-PCHSC is a facility founded by The Department of Communication Sciences and Disorders of the University of South Florida, with Dr. Arthur M. Guilford as chairman. Researchers have determined that hearing loss is one of the three most prevalent medical conditions in the United States, affecting more than 28 million people over the age of sixty-five (Martin and Clark, 2002). According to yellowpages.com there are twenty-five hearing …

Operational Evaluation Of Right Turns Followed By U-Turns At Signalized Intersections As An Alternative To Direct Left Turns, Jingjing Fan

USF Tampa Graduate Theses and Dissertations

Direct left turn (DLT) movements have a lot safety and operation problems. They increase conflicts, delay and reduce capacity of the roadway. Increasing, many states and transportation agencies are considering using right-turns followed by u-turns as an alternative to direct left turns. Recently, Florida state are planning to close median openings in order to reduce the safety and operational problems caused by DLT. The left-turn egress movement would then to be made by turning right to the arterial road and then making a u-turn at an available downstream median opening or a signalized intersection. FDOT sponsored a project in 2001 …

Crystal Engineering Of Metal-Carboxylate Based Coordination Polymers, Jianjiang Lu

USF Tampa Graduate Theses and Dissertations

This dissertation endeavors to delineate practical paradigms for crystal engineering based upon the understanding of supramolecular chemistry and self-assembly, i.e. the design and synthesis of novel functional crystalline materials.

Two basic metal-organic building units, Zn(RCO₂)₂(py)₂ and (L₂)M₂(RCO₂)₄ (M = Zn, Cu), as well as nano-scaled secondary building units (nSBUs) that are constructed from Cu₂(RCO₂)₄ are researched and discussed. Design strategies have been developed to propagate these metal-organic synthons into predictable coordination polymer networks. A series of crystal structures, as well as their syntheses …