Digital Commons Network^™

An Automatic Code Generation Tool For Partitioned Software In Distributed Computing, Neeta S. Singh

USF Tampa Graduate Theses and Dissertations

In a large class of distributed embedded systems, most of the code generation models in use today target at object-oriented applications. Distributed computing using procedural language applications is challenging because there are no compatible code generators to test the partitioned programs mapped on to the multi-processor system. In this thesis, we design a code generator to produce procedural language code for a distributed embedded system. Unpartitioned programs along with the partition primitives are converted into independently executable concrete implementations. The process consists of two steps, first translating the primitives of the unpartitioned program into equivalent code clusters, and then scheduling …

Design And Fabrication Of A Re-Configurable Micromirror Array For An Optical Microspectrometer, Vandana Upadhyay

USF Tampa Graduate Theses and Dissertations

This thesis presents the design and fabrication of a re-configurable micromirror array which can be used as a component of an optical microspectrometer. In an optical microspectrometer, an array of mechanically positionable micromirrors can be implemented as a reconfigurable exit slit to selectively focus particular wavelengths of a diffracted spectrum onto the detector stage. The signal to noise ratio and response time of an optical microspectrometer can be vastly improved by this technique.

In the approach presented here, a hybrid bulk- and surface- micromachining process is demonstrated for fabrication of a 1XN array of micromirrors. The reconfigurable micromirrors presented here …

Usfkad: An Expert System For Partial Differential Equations, Sami M. Kadamani

USF Tampa Graduate Theses and Dissertations

USFKAD is an encoded expert system for the eigenfunction expansion of solutions to the wave, diffusion, and Laplace equations: both homogeneous and nonhomogenous; one, two, or three dimensions; Cartesian, cylindrical, or spherical coordinates; Dirichlet, Neumann, Robin, or singular boundary conditions; in time, frequency, or Laplace domain. The user follows a menu to enter his/her choices and the output is a LaTeX file containing the formula for the solution together with the transcendental equation for the eigenvalues (if necessary) and the projection formulas for the coefficients. The file is suitable for insertion into a book or journal article, and as a …

Improving Accuracy In Logarithmic Multiplication Using Operand Decomposition, Mahalingam Venkataraman

USF Tampa Graduate Theses and Dissertations

The arithmetic operations such as multiplication and division in binary number system are computationally complex in terms of area, delay and power. Logarithmic Number Systems (LNS) offer a viable alternative combining the simplicity of fixed point number systems and the precision of floating point number systems. However, the computations in LNS result in some loss of accuracy and thus, are limited to mostly signal processing applications; where in certain amount of error is tolerable. In LNS, the cost of computations can be tradeoff with the level of accuracy needed. The Mitchell algorithm proposed incite[mitchell], is a simple approach commonly used …

Analysis Of The Impact Of The Location Of A Window Type Air-Conditioner On Thermal Comfort In An Office Room, Hamza Begdouri

USF Tampa Graduate Theses and Dissertations

This study considers airflow simulations to evaluate the impact of different window air-conditioner locations on the thermal comfort in an office room (OR). This thesis compares the air distribution for an office room by using computational fluid dynamics (CFD) modeling to previously studied rooms. The air distribution was modeled on a typical office room window air conditioning unit, air supply from a high pressure on the top and the low pressure exhaust on the bottom considering the existing manufacturing ratios for surface areas. The discharge angle for the supply grill of the AC unit was varied from 20 to 40 …

The Effects Of Moisture On Thin Film Delamination And Adhesion, Patrick Waters

USF Tampa Graduate Theses and Dissertations

Significant drops in adhesion have been measured for copper and diamond like carbon (DLC) films with the introduction of water at the film/substrate interface. A 1 thick tungsten superlayer with high compressive residual stress was deposited on the films of interest to help induce interfacial debonding by indentation. Modifications were made to the superlayer indentation technique to introduce water at the interface while performing indents. Film adhesion dropped by a factor of 10 to 20 for the copper films and 50 to 60 for the DLC films. The reduction in adhesion is believed to be caused by a combination of …

Low Loss Rf/Millimeter-Wave Mems Phase Shifters, Balaji Lakshminarayanan

USF Tampa Graduate Theses and Dissertations

A true time delay multi-bit MEMS phase shifter topology based on impedance-matched slow-wave CPW sections on a 500µm thick quartz substrate is presented. Design equations based on the approximate model for a distributed line is derived and used in optimization of the unit cell parameters. A semi-lumped model for the unit cell is derived and its equivalent circuit parameters are extracted from measurement and EM simulation data. This unit cell model can be cascaded to accurately predict N-section phase shifter performance. Experimental data for a 4.6mm long 4-bit device shows a maximum phase error of 5.5° and S₁₁ less …

Auction Performance Evaluation In Deregulated Electricity Markets, Vishnuteja Nanduri

USF Tampa Graduate Theses and Dissertations

In a deregulated electricity market, auction serves as a primary pricing tool in various segments of the market including day-ahead, real time, ancillary services markets, and Financial Transmission Rights (FTRs) market. Deregulated power markets around the world use different auction strategies that exist in the literature, since very little comparative guidelines exist as to the relative merits of these strategies. In this thesis, a computational methodology and its solution framework are developed to evaluate the impact of an auction strategy on the equilibrium prices in a constrained network with multiple generators at nodes, and where transactions are settled using the …

Effect Of Fiber Volume Fraction On Fracture Mechanics In Continuously Reinforced Fiber Composite Materials, Thomas Wasik

USF Tampa Graduate Theses and Dissertations

The application of advanced composite materials, such as graphite/epoxy, has been on the rise for the last four decades. The mechanical advantages, such as their higher specific stiffness and strength as compared to monolithic materials, make them attractive for aerospace and automotive applications. Despite these advantages, composites with brittle fibers have lower ductility and fracture toughness than monolithic materials.

One way to increase the fracture toughness of composites is to have a weak fiber-matrix interface that would blunt crack tips by crack deflection into the interface and hence enhance fracture toughness. However, this also reduces the transverse properties of the …

Integrated Scheduling And Information Support System For Transit Maintenance Departments, Paula Andrea Lopez Alvarado

USF Tampa Graduate Theses and Dissertations

The projected increase of population in the United States and particularly in the state of Florida shows a clear need of improvement in mass transportation systems. To provide outstanding service to rides, well maintained fleet that ensures safety for riders and other people on the streets is imperative.

This research presents an information support system that assists maintenance managers to review and analyze data and evaluate alternatives in order to make better decisions that maximize efficiency in operations at transportation organizations. A system that consists of a mathematical scheduling model that interacts with a forecasting model and repair time standards …

Performance Evaluation Of Mobile Ad Hoc Networks In Realistic Mobility And Fading Environments, Preetha Prabhakaran

USF Tampa Graduate Theses and Dissertations

Mobile Ad hoc Networks (MANETs) are wireless networks, which consist of a collection of mobile nodes with no fixed infrastructure, where each node acts as a router that participates in forwarding data packets. They are a new paradigm of wireless communications for mobile hosts that are resource-constrained with only limited energy, computing power and memory.

Previous studies on MANETs concentrated more on energy conservation in an idealistic environment without taking into consideration, the effects of realistic mobility, interference and fading. The definition of realistic mobility models is one of the most critical and, at the same time, difficult aspects of …

Partial Evaluation Based Triple Modular Redundancy For Single Event Upset Mitigation, Sujana Kakarla

USF Tampa Graduate Theses and Dissertations

We present a design technique, called partial evaluation triple modular redundancy for hardening combinational circuits against Single Event Upsets (SEU). The input environment is given in terms of signal probabilities of the lines. This is useful information to determine the redundant gates of the given circuit. The basic ideas of partial redundancy and temporal triple modular redundancy are used together to harden the circuit against SEUs. The concept of partial redundancy is used to eliminate the gates whose outputs can be determined in advance. This technique fails in cases when the actual inputs to the circuit are not in accordance …

An Investigation Of Tio2-Znfe2O4 Nanocomposites For Visible Light Photocatalysis, Jeremy Wade

USF Tampa Graduate Theses and Dissertations

Environmental pollution on a global scale is expected to be the greatest problem that chemical scientists will face in the 21st century, and an increasing number of these scientists are looking to new photocatalytic systems for the solution. Existing photocatalytic systems are effective for the decomposition of many unwanted organics through the use of efficient semiconductor photocatalysts activated by ultra-violet (UV) irradiation. The demand for visible light activated photocatalytic systems is increasing rapidly. Currently, however, the efficiency and availability of photocatalysts which can be activated effectively by the solar spectrum and especially indoor lighting is severely limited.

The purpose of …

Novel Rectenna For Collection Of Infrared And Visible Radiation, Mohammad Sarehraz

USF Tampa Graduate Theses and Dissertations

This dissertation presents the rectifying antennas potential for harvesting solar power, along with a novel design for a solar rectenna. The suns general features and the characteristics of solar radiation as an electromagnetic wave are treated in depth in order to determine the deficiencies of traditional rectennas as a solar cell. A closed form equation for a MIM rectifiers efficiency as a function of its input power was developed and verified by a simulated behavioral model and measurements. A unique calculation method was also developed to determine the available solar power at the terminal of a [lambda]/2 dipole antenna as …

Structural And Electrical Properties Of Barium Strontium Titanate Thin Films For Tunable Microwave Applications, Sriraj G. Manavalan

USF Tampa Graduate Theses and Dissertations

The dependence of dielectric permittivity on the applied electric field, high dielectric constant and low cost makes barium strontium titanate (BST) a promising ferroelectric material for applications in tunable microwave devices. High tunability and low dielectric loss is desired for tunable microwave devices. The primary objective of this research was to optimize the tunability and dielectric loss of BST thin films at microwave frequencies with different deposition techniques. Ba0.5Sr0.5TiO3 thin films were grown on Pt/TiO₂/SiO₂/Si, by pulsed laser deposition (PLD) and sputtering. Parallel plate capacitor structures were designed using ADS and fabricated. The microstructural and phase …

Cds/Cdte Thin Film Solar Cells With Zinc Stannate Buffer Layer, Srilatha Bapanapalli

USF Tampa Graduate Theses and Dissertations

CdS/CdTe solar cell performance and reproducibility can be improved by integrating a ZTO buffer layer, which interdiffuses into the CdS layer during device fabrication. Reducing the thickness of CdS layer improves the QE in the blue spectral region without affecting the device performance. This buffer layer is expected to prevent the formation of localized TCO/CdTe junction during high temperature processing.

The CdS/CdTe Solar Cell was modified by introducing ZTO as a buffer layer between the window layer (CdS) and the absorber layer (CdTe). Studies were performed on different varying ZTO processing parameters like (a) Zn/Sn atomic ratios during sputtering process, …

Study Of Tin Oxide For Hydrogen Gas Sensor Applications, Manoj Anand

USF Tampa Graduate Theses and Dissertations

Tin oxide (SnO₂) has been investigated and used as a gas sensing material for numerous applications from the very start of the sensor industry. Most of these sensors use semiconductors (mostly SnO₂) as the sensing material.

In this work, SnO₂ was prepared using 2 techniques: firstly the MOCVD where we dope the sample with fluorine and secondly sputtering technique where samples are undoped in our case. These samples were tested at different conditions of temperature varying from room temperature to 150 degrees C, in ambient gas atmosphere of 200 CC Nitrogen (N₂).

The …

Development And Characterization Of Carbon Nanotubes For Sensor Applications, Jessica Eileen Otto

USF Tampa Graduate Theses and Dissertations

The aim of this research was to develop, characterize, and analyze carbon nanotubes as biosensors. In particular, pH and lactate molecules were targeted in this study. The reason these analytes were chosen was twofold. Firstly, when hydrogen ions and lactate are excreted in abnormal amounts in human sweat, they may be an indicator of a separate health problem. Thus, there is a clinical need for such biosensor applications. Secondly, pH and lactate detection represent two different types of electrochemical sensing techniques.

The carbon nanotubes used in this research were single walled and existed in bundles. They were further functionalized with …

Effect Of Sno2 Roughness And Cds Thickness On The Performance Of Cds/Cdte Solar Cells, Lingeshwar Nemani

USF Tampa Graduate Theses and Dissertations

Textured SnO₂ films as TCO have been investigated to determine the effect of surface roughness on the performance of CdS/CdTe solar cells. Film roughness was controlled by varying the substrate temperature. Characterization of the SnO2 films has also carried out using AFM measurements. It was found that increase in substrate temperature results in increased roughness of the film.

A series of cells were fabricated with different CdS thicknesses to determine the combined effect of SnO₂ roughness and CdS thickness. As a part of fabrication process, cells were subjected to different post deposition treatments. It was observed that roughness …

An Implementation Of The Usf/ Calvo Model In Verilog-A To Enforce Charge Conservation In Applicable Fet Models, Joshua Nicodemus

USF Tampa Graduate Theses and Dissertations

The primary goal of this research is to put into code a unique approach to addressing problems apparent with nonlinear FET models which were exposed by Calvo in her work in 1994. Since that time, the simulation software for which her model was appropriate underwent a significant update, necessitating the rewriting of her model code for a few applicable FET models in a Verilog-A, making it more compatible with the new versions of software and simulators.

The problems addressed are the inconsistencies between the small-signal model and the corresponding large-signal models due to a factor called transcapacitance. It has been …

Computation Of Fluid Circulation In A Cryogenic Storage Tank And Heat Transfer Analysis During Jet Impingement, Santosh Kumar Mukka

USF Tampa Graduate Theses and Dissertations

The study presents a systematic single and two-phase analysis of fluid flow and heat transfer in a liquid hydrogen storage vessel for both earth and space applications.The study considered a cylindrical tank with elliptical top and bottom. The tank wall ismade 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 …

Design And Evaluation Of A New Authentication Mechanism For Validating The Sender Of An Email, Sai Sakamuri

USF Tampa Graduate Theses and Dissertations

A new authentication mechanism for validating the source of messages over the Internet is designed and evaluated. This mechanism is applied to email and is called Email++. Email++ prevents identity forging (spoofing) and tampering of email contents. By preventing identity forging, Email++ can reduce the amount of spam received and limit the spread of viruses like Melissa, Love Bug, Bagle Worm, and Killer Resume. Email++ validates both the sender and the receiver of an email by confirming the senders identity with the domain mail server that delivered the email for the sender, and authenticates the receiver with hash value comparisons. …

Optimization Study Of Ba-Filled Si-Ge Alloy Type I Semiconducting Clathrates For Thermoelectric Applications, Joshua Martin

USF Tampa Graduate Theses and Dissertations

Thermoelectric phenomena couple thermal and electric currents, allowing for solid-state conversion of heat into electricity. For decades Radioisotope Thermoelectric Generators have supplied power to NASA satellites and deep space probes. A more accessible application to consumers is the automotive industry's aspiration to incorporate thermoelectrics into active waste heat recovery systems. Higher power demands require these new thermoelectric devices to operate at higher temperatures and higher efficiencies, justifying new materials research. Recently, clathrates have gained interest for thermoelectric applications due to the unique properties they possess.These properties are directly related to their crystal structure. Therefore, clathrates are not only of interest …

System Level Energy Optimization For Location Aware Computing, Hariharan Sankaran

USF Tampa Graduate Theses and Dissertations

We present an energy conscious location-aware computing system that provides relevant information about the users current location. The location-aware computing system is initialized with a map (in the form of a graph) as well as audio files associated with several locations in the map. The system consists of: GPS receiver module, Serial port, Compact flash module, Stereo codec, Power manager module implementing three sub modules namely, GPS-to-real-world position conversion module (implements algorithm to convert GPS co-ordinates to graph nodes), Nearest-location-search module (implements modified Dijkstras algorithm), and User speed estimation module. The location-aware computing system receives the GPS co-ordinates for the …

Supercritical Carbon Dioxide Aided Preparation Of Nickel Oxide/Alumina Aerogel Catalyst, Haitao Li

USF Tampa Graduate Theses and Dissertations

The strength, thermal stability, pore structure and morphology are keys to success for wider deployment of aerogels. Furthermore, co or subsequent functionalization of the surfaces are equally, if not more important. This study addresses these issues through a new method. The path involves successful use of surfactant templating, supercritical extraction and drying, and supercritical fluid aided functionalization of the surface. Alumina support and alumina supported nickel catalyst particles are used to evaluate the approach. Initially thermally stable surfactant alumina was synthesized. The surfactant template was removed completely with the aid of a supercritical solvent mixture. Surfactant-templated alumina aerogel showed remarkable …

Scaling Up Support Vector Machines With Application To Plankton Recognition, Tong Luo

USF Tampa Graduate Theses and Dissertations

Learning a predictive model for a large scale real-world problem presents several challenges: the choice of a good feature set and a scalable machine learning algorithm with small generalization error. A support vector machine (SVM), based on statistical learning theory, obtains good generalization by restricting the capacity of its hypothesis space. A SVM outperforms classical learning algorithms on many benchmark data sets. Its excellent performance makes it the ideal choice for pattern recognition problems. However, training a SVM involves constrained quadratic programming, which leads to poor scalability. In this dissertation, we propose several methods to improve a SVM's scalability. The …

Sensitivity Analysis Of Design Parameters For Trunnion-Hub Assemblies Of Bascule Bridges Using Finite Element Methods, Jai P. Paul

USF Tampa Graduate Theses and Dissertations

Hundreds of thousands of dollars could be lost due to failures during the fabrication of Trunnion-Hub-Girder (THG) assemblies of bascule bridges. Two different procedures are currently utilized for the THG assembly. Crack formations in the hubs of various bridges during assembly led the Florida Department of Transportation (FDOT) to commission a project to investigate why the assemblies failed.

Consequently, a research contract was granted to the Mechanical Engineering department at USF in 1998 to conduct theoretical, numerical and experimental studies. It was found that the steady state stresses were well below the yield strength of the material and could not …

Voices From A Marginalized Population: Life Histories Of Individuals With Physical Impairments, James Peter Marsh

USF Tampa Graduate Theses and Dissertations

Individuals with physical impairments have been marginalized and discriminated against since the social identification of these individuals occurred as a sub-group within society. While much has been done to resolve prejudice against individuals with physical impairments, more needs to be done to decrease, or at least deter, discrimination and prejudice against individuals who have been marginalized. The purpose of this study is to give four individuals with physical impairments the opportunity to tell their stories. Through the telling of these stories, I believe others can identify with these individuals, and thereby, help decrease discrimination against individuals with physical impairments.

Life …

Effect Of Heat Treatments And Reduced Absorber Layer Thickness On Cu(In,Ga)Se2 Thin Film Solar Cells, Vinodh Chandrasekaran

USF Tampa Graduate Theses and Dissertations

Thin film solar cells with Copper Indium Gallium Diselenide (Cu(In,Ga)Se₂) absorber layers is one of the most promising candidates to emerge as an efficient solar cell technology in the near future. CIGS cells with efficiencies of 19.2 % have already been reported [1]. In this study, CIGS absorber layers are fabricated by a two-stage all-solidstate manufacture-friendly process. In the first stage, designated as precursor deposition, Copper and Gallium are sequentially deposited followed by co-deposition of Indium and Selenium. In the second stage, designated as selenization, the substrate is annealed at high temperatures in a selenium environment during which …

Stability Studies Of Cdte/Cds Thin Film Solar Cells, Bhaskar Reddy Tetali

USF Tampa Graduate Theses and Dissertations

CdTe/CdS solar cells have shown great potential for terrestrial solar power applications. To be commercially viable they need to operate efficiently for about 30 years. CdS/CdTe solar cells fabricated at USF have shown record efficiencies upto 16.5% [46]. This research involves the study of thermal stress (TS) and light soaking (LS) on the stability of high efficiency (>10%) solar cells. The change in key electrical parameters V_oc, FF, J_sc, A and J_o are quantified for more than 2000 hours of stressing.

The device degradation was found to increase with stress temperature for TS. Below …