Digital Commons Network^™

Optimization Of The Two Stage Process For Cu(In,Ga)Se2 Solar Cells, Shirish Pethe

USF Tampa Graduate Theses and Dissertations

Copper Indium Gallium DiSelenide absorber layers are fabricated using a two stage manufacturing friendly process. The first step involves the sequential deposition of Copper and Gallium and co-deposition of indium and selenium at 275oC. 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 CIGS absorber layer. The top copper thickness as well as the time of deposition was varied to study the effect of Copper on the performance of the cells. …

Congestion-Aware Cross-Layer Design For Wireless Ad Hoc Networks, Ning, Yang

USF Tampa Graduate Theses and Dissertations

Ad hoc networks have emerged recently as an important trend of future wireless systems. The evolving wireless networks are seriously challenging the traditional OSI layered design. In order to provide high capacity wireless access and support new multimedia network, the various OSI layers and network functions should be considered together while designing the network.

In this thesis, we briefly discuss performance optimization challenges of ad hoc networks and cross-layer design. Ad hoc wireless networks were implemented by using Network Simulator NS-2 and the wireless physical, data link, dynamic source routing (DSR) routing protocol models have been included in the simulation. …

Deadlock Avoidance In Mixed Capacity Flexible Manufacturing Systems, Sridhar Mohan

USF Tampa Graduate Theses and Dissertations

This research addressed the design and implementation of a polynomial-complexity deadlock avoidance controller for a flexible manufacturing cell modeled using Colored Petri Nets. The cell model is robust to changes in the part types to be manufactured in the system and is automatically generated using the interaction of the resources in the cell and the technological capabilities of the machines. The model also captures dynamic routing flexibility options. The framework introduced separates the cell model from the control logic allowing the system designer to implement and test various control algorithms using the same cell model. The controller adopts the neighborhood …

Analysis Of Fluid Circulation In A Spherical Cryogenic Storage Tank And Conjugate Heat Transfer In A Circular Microtube, P Sharath Chandra Rao

USF Tampa Graduate Theses and Dissertations

The study considered development of a finite-element numerical simulation model for the analysis of fluid flow and conjugate heat transfer in a zero boil-off (ZBO) cryogenic storage system. A spherical tank was considered for the investigation. The tank wall is made of aluminum and a multi-layered blanket of cryogenic insulation (MLI) has been attached on the top of the aluminum. The tank is connected to a cryocooler to dissipate the heat leak through the insulation and tank wall into the fluid within the tank. The cryocooler has not been modeled; only the flow in and out of the tank to …

Development Of Surface Acoustic Wave Sensors Using Nanostructured Palladium For Hydrogen Detection, Amol V. Chaudhari

USF Tampa Graduate Theses and Dissertations

This thesis addresses the development of new gas sensor using surface acoustic wave (SAW) technology. SAW sensors detect the change in mass, modulus, and conductivity of a sensing layer material via absorption or adsorption of an analyte. The advantage of SAW sensor includes low cost, small size, high sensitivity.

We investigated the use of nano-crystalline palladium film for sensing hydrogen gas. We also investigated SAW fabrication for radio frequency (RF) range operation where high signal-to-noise ratios can be achieved. A test-bed consisting of a gas dilution system, a temperature-controlled test cell, a network analyzer, and computer-based measurement system was used …

Fuzzy C-Means Clustering Approach To Design A Warehouse Layout, Vaibhav C. Naik

USF Tampa Graduate Theses and Dissertations

Allocation of products in a warehouse is done by various storage policies. These are broadly classified into three main categories: dedicated storage, randomized storage, and class-based storage. In dedicated storage policy a product is assigned a designated slot while in random storage policy incoming product is randomly assigned a storage location close to the input/output point. Finally, the class-based storage is a mixed policy where products are randomly assigned within their fixed class. Dedicated storage policy is most commonly used in practice. While designing large warehouse layout, the product information in terms of throughput and storage level is either uncertain …

Performance Analysis Of Tcp/Ip Over High Bandwidth Delay Product Networks, Subodh Kerkar

USF Tampa Graduate Theses and Dissertations

In today's Internet scenario, the current TCP has performed reasonably well. As the Internet has scaled up in load, speed, size and connectivity by the order of six over the past fifteen years, the TCP has consistently avoided severe congestion throughout this same period. Applications involving high performance computings such as bulk-data transfer, multimedia Web streaming, and computational grids demand high bandwidth. These applications usually operate over wide-area networks and, hence, performance over wide-area networks has become a critical issue. Future applications will need steady transfer rates in the order of gigabits per second to support collaborative work. TCP, which …

Characterization Of P-Type Zinc Oxide Films, Madhavi Oleti Kalki Rajan

USF Tampa Graduate Theses and Dissertations

Zinc Oxide falls under the classification of transparent conductive oxides. They typical optical transmittance of Zinc Oxide is 90% in the visible wavelength region. Though stoichiometric ZnO is an insulator, due to the presence of internal defects such as Zn interstitials and Oxygen vacancies, it exists as a n-type conductor.

The other important property of ZnO which could be used by the optical field is its widebandgap. ZnO has a wide bandgap of 3.2eV -3.3eV. The additional advantage of being a direct bandgap semiconductor has increased the probability of using ZnO for short wavelength applications. These practical applications are directly …

Characterization Of Preliminary Breast Tomosynthesis Data: Noise And Power Spectra Analysis, Madhusmita Behera

USF Tampa Graduate Theses and Dissertations

Early detection, diagnosis, and suitable treatment are known to significantly improve the chance of survival for breast cancer (BC) patients. To date, the most cost effective method for screening and early detection is screen-film mammography, which is also the only tool that has demonstrated its ability to reduce BC mortality. Full-field digital mammography (FFDM) is an extension of screen-film mammography that eliminates the need for film-processing because the images are detected electronically from their inception. Tomosynthesis is an emerging technology in digital mammography built on the FFDM framework, which offers an alternative to conventional two-dimensional mammography. Tomosynthesis produces three-dimensional (volumetric) …

An Analysis Of Travel Trends Of The Elderly And Zero-Vehicle Households In The United States, Ravi Kiran Gorti

USF Tampa Graduate Theses and Dissertations

The elderly and persons residing in zero vehicle households require better transportation services by virtue of their need for special care and lack of mobility, respectively. An analysis of the travel trends of these population cohorts is essential to determine the best ways to improve transportation facilities to better serve them. Information about location of residence, life-cycle, differences by gender, employment status, driver status, highest level of education coupled with trip information like trip rate, travel times and distances trip purpose, modal split and percent of people immobile will facilitate understanding the factors that influence trip making among these people …

Hydraulic Performance Of Polymer Modified Bentonite, Jessica A. Schenning

USF Tampa Graduate Theses and Dissertations

Bentonite clay is widely used in barrier systems due to its low hydraulic conductivity and it high swell capacity. Exposure to inorganic solutions can cause significant increases in hydraulic conductivity, due to changes in the surface chemistry and fabric. This phenomenon can be attributed to a reduction in the thickness of the double layer, due to the cation exchange capacity of the clay. The clay can be modified with polymers to render it less susceptible to chemical attack. The treatment process allows the clay to be engineered to enhance specific properties, such as permeability and sorption. In the present study, …

Analysis Of Glass Mold To Enhance Rate Of Heat Transfer, Anand Warude

USF Tampa Graduate Theses and Dissertations

Narrow Neck Press and Blow (NNPB) process is used to produce light weight bottles. The gob of molten glass is delivered to the blank mold and a specially designed narrow diameter plunger is used to form the finish or mouth and the parison as it presses upwards. Invert and final blow takes place followed by take-out and annealing. Anchor Glass Container Corp. (AGC) uses NNPB technology in their glass making plants. The problem experienced by AGC in the process is that the heat dissipation through out the mold is not uniform and hence there is a non uniform temperature distribution …

A Model For Strategic Bidding In Combined Transmission And Wholesale Energy Markets, Sanket Gupte

USF Tampa Graduate Theses and Dissertations

Motivated by deregulation in major service sectors like airlines, banking and telecommunication, the electric industry is undergoing a major transformation. However due to design inefficiencies, restructuring of the power sector, so far, has not been a major success. A lack of comprehensive quantitative models has resulted in the inability of the market designers to evaluate market performance and develop successful market designs. A comprehensive model should include market features like two-settlement system, transmission congestion, financial transmission rights (FTRs), demand elasticity, demand-side bidding and other market rules.

The contribution of this thesis includes development of an exhaustive modeling framework that includes …

Effects Of Aspirin And Its Derivatives In Combination With Electroporation For Drug Delivery In Cultured Cells, Jennifer Langham

USF Tampa Graduate Theses and Dissertations

The purpose of this research was to investigate the effects that aspirin (ASA) and its metabolites, salicylic acid (SA) and acetic acid (AA), have on the delivery of drugs across biological barriers when used in conjunction with electroporation. Electroporation is a technique used to enhance drug delivery across bio-membranes in which a transmembrane potential is induced into cellular membranes, resulting in the creation of aqueous pores that allow molecules to pass through the otherwise impermeable barrier. Aspirin is a widely used drug that has been used for over a century and has been proven relatively safe at normal doses as …

Robust Dock Assignments At Less-Than-Truckload Terminals, Mesut Korhan Acar

USF Tampa Graduate Theses and Dissertations

Less-than-truckload industry has a valuable potential for applications of operations research in two areas, network design and efficiency improvement within existing networks. This thesis focuses on the latter, specifically the less-than-truckload terminals where cross docking operations occur.

The assignment of incoming trailers to inbound docks is one of the critical decisions that affect the performance of less-than-truckload terminals. This research reviews existing models in literature and introduces an optimal mixed integer quadratic model with the objective of generating assignments that are robust against variability in system parameters such as truck arrival and service times, terminal characteristics and trailer load content. …

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 …

The Perceived Impact Of The Individuals With Disabilities Education Act (Idea), 1997 Disciplinary Mandates On The School Board Policies In Three Urban, K-12 Public School Districts, Nancy S. Zambito

USF Tampa Graduate Theses and Dissertations

In 1990 the Individuals with Disabilities Education Act (IDEA) required that states provide a free and appropriate education to all children and youth with disabilities, no matter how severe the disabilities. This obligation was tied to federal funding and outlined in detail parental rights with regard to identifying and educating their child with disabilities. The 1997 reauthorization of IDEA stepped into school discipline, creating a complex process for addressing school misconduct of such students.

This study determines how the 1997 IDEA disciplinary mandates, as they existed until May 2003, were interpreted and implemented in three similar, urban, public school districts …

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 …

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 …

The Role Of Intelligence And Coping Processes On Resilience In Adult Survivors Of Childhood Sexual Abuse, Kelli-Lee Harford

USF Tampa Graduate Theses and Dissertations

The relationship between intelligence as measured by the Shipley Institute of Living Scale, Coping Processes as measured by the Ways of Coping Scale and resilience as measured by Global Severity Index of the Brief Symptom Inventory, was examined in 88 individuals who had been sexually abused and 88 individuals who had not been sexually abused. The study attempted to assess whether more intelligent individuals and those who used certain coping styles would experience less distress in the face of adversity than individuals with lower levels of intelligence and who used different coping styles. The results indicated that intelligence was not …

The Quality Of Life Among Lymphedema Patients Due To Lymphatic Filariasis In Three Rural Towns In Haiti, Koji Kanda

USF Tampa Graduate Theses and Dissertations

The worldwide eradication of lymphatic filariasis has recently started with two strategies, interruption of transmission and morbidity control. One of the most endemic countries, Haiti has experienced successful interventions through national and international efforts, but the morbidity control is still hindered by a lack of adequate information on quality of life (QOL) issues among those suffering from the chronic manifestations of the disease such as lymphedema. In addition, previous interventions have been focused primarily in a single community where an established lymphedema treatment clinic serves as a national reference center, so it is critical to expand programs to other areas …

Socio-Spatial Polarization In St. Petersburg, Florida: A Critical Evaluation Of The Vision 2020 Plan, Jacqueline Salmond

USF Tampa Graduate Theses and Dissertations

Those who are given access to develop and plan our urban areas are in possession of great power and potential. With the vast sums of both private and governmental money associated with the creation and organization of urban areas, the motivations of those constructing plans and deciding developmental strategies need to be considered. When a city has a dual identity and is socially and spatially conflicted, then the task of planning equitably for all residents becomes even more complex. The extent to which planners address the needs of their community, and the divisions which may exist, reveals the intentions of …

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 …

Synthesis And Magnetic Properties Of Polymer Nanocomposites, Jessica L. Wilson

USF Tampa Graduate Theses and Dissertations

Magnetic nanoparticles embedded in polymer matrices have excellent potential for electromagnetic device applications like electromagnetic interference (EMI) suppression. Using chemical precipitation methods and Nanogen , a microwave plasma method, we have synthesized various nanoparticles including iron, polystyrene-coated iron, iron oxide (both hematite and magnetite), nickel ferrite, and manganese zinc ferrite. We have synthesized polymer nanocomposites of polymethylmethacrylate (PMMA), polystyrene (PS), and polypyrrole (PPy) doped with varying concentrations of these nanoparticles. These nanocomposites were processed using melt blending and sonication techniques. The concentration of nanoparticles was varied in a controlled way. Although polymer processing conditions were optimized to achieve good uniform …

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 …