Digital Commons Network^™

Structuring Emperical Methods For Reuse And Efficiency In Product Development Processes, Marshall Edwin Bare

Theses and Dissertations

Product development requires that engineers have the ability to predict product performance. When product performance involves complex physics and natural phenomena, mathematical models are often insufficient to provide accurate predictions. Engineering companies compensate for this deficiency by testing prototypes to obtain empirical data that can be used in place of predictive models. The purpose of this work is to provide techniques and methods for efficient use of empirical methods in product development processes. Empirical methods involve the design and creation of prototype hardware and the testing of that hardware in controlled environments. Empirical methods represent a complete product development sub-cycle …

Constitutive Modeling Of The Thermo-Mechanics Associated With Crystallizable Shape Memory Polymers, Gautam Barot

Dissertations

This research addresses issues central to material modeling and process simulations. Here, issues related for developing constitutive model for crystallizable shape memory polymers are addressed in details. Shape memory polymers are novel material that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. The temporary shape is stable and return to the original shape is triggered by a suitable mechanism such heating the polymer above a transition temperature. Crystallizable shape memory polymers are called crystallizable because the temporary shape is fixed by a crystalline phase, while return to the original shape …

Modeling Holographic Grating Imaging Systems Using The Angular Spectrum Propagation Method, Thomas Blasiak

Theses

The goal of this research was to describe the angular spectrum propagation method for the numerical calculation of scalar optical propagation phenomena. The angular spectrum propagation method has some advantages over the Fresnel propagation method for modeling low F# optical systems and non-paraxial systems. An example of one such system was modeled, namely the diffraction and propagation from a holographic diffraction grating. To accomplish this goal MATLAB® code was developed to implement the angular spectrum propagation method. Some classical imaging problems such as diffraction from a rectangular aperture, Talbot imaging, focal shift for converging beam illumination, and two beam interference …

A Generalized Three-Phase Coupling Method For Distributed Simulation Of Power Systems, Jian Wu

Theses and Dissertations

Simulation of power system behavior is a highly useful tool for planning, analysis of stability, and operator training. Traditionally, small power system studies are dominated by the time taken to solve the machine dynamics equations, while larger studies are dominated by the time taken to solve the network equations. With the trend towards more sophisticated and realistic modeling, the size and complexity of simulations of a power system grow tremendously. The ever-increasing need for computational power can be satisfied by the application of distributed simulation. Also power systems are distributed in nature. The terrestrial power systems are divided into groups …

Black Liquor Droplet Combustion And Modeling, Warren Benjamin Roberts

Theses and Dissertations

Black liquor is an intermediate product of pulp production. Recovery boilers process black liquor to recover the inorganic material for recycling in the mill and to generate electricity and steam for the paper mill. Black liquor droplet combustion rates and mechanisms dictate many aspects of recovery boiler performance. This investigation documents new experimental data on single droplet pyrolysis and combustion in a laboratory furnace that mimics many of the essential features of commercial boilers (temperature, composition, droplet size, etc.). These experiments monitored single droplets placed on a thermocouple wire and suspended from a mass balance. Simultaneous video images and pyrometry …

Saharan Dust And Phosphatic Fidelity: A Three Dimensional Biogeochemical Model Of Trichodesmium On The West Florida Shelf, Jason M. Lenes

USF Tampa Graduate Theses and Dissertations

The availability of iron within the surface waters of the broad, oligotrophic West Florida shelf (WFS) controls periodic blooms of the pelagic marine cyanobacterium Trichodesmium. Summer delivery of iron (Fe), in the form of Saharan dust, alleviates this growth constraint, shifting limitation to the efficiency of phosphorus (P) cycles. Florida's rivers drain Miocene phosphorus deposits to supply the WFS with freshwater nutrient supplies at molar dissolved inorganic nitrogen/phosphate (DIN/PO4) ratios of less than 6. These diazotrophs draw upon ubiquitous stocks of dissolved nitrogen gas, once stimulated by Fe-deposition within P-replete waters of the West Florida shelf. An extensive in situ …

Water Quality, Modeling, And Land Use Investigations In The Upper Pearl River Basin Of East-Central Mississippi, Mary Love Mortimer Tagert

Theses and Dissertations

Little historical water quality data is available for the Upper Pearl River Basin (UPRB), yet there are UPRB waters listed as impaired. Objectives of this research were to measure pesticide and sediment concentrations in UPRB surface waters and validate the Annualized Agricultural Nonpoint-Source (AnnAGNPS) runoff model with the measured data for a portion of the UPRB. An additional objective was to quantify effects of land use changes on UPRB surface waters from 1987 to 2002 using AnnAGNPS. Of the fifteen compounds analyzed, hexazinone was most frequently detected, in 94% of samples, followed by metolachlor, tebuthiuron, and atrazine. Metribuzin was detected …

System Optimization For Micron And Sub-Micron Particle Identification Using Spectroscopy-Based Techniques, Eduardo Zurek

USF Tampa Graduate Theses and Dissertations

This dissertation describes an approach and a model for the analysis of critical parameters related to the optical and electronic components of spectroscopy systems. The model described herein enables a systematic study of the impact of these parameters on the total performance of the system; therefore, it is a tool for the design and optimization of spectrometers.

Although the physics of the optical and electronic components in spectroscopy systems are known and well established, the systemic approach to the understanding of their interactions is recent and it is an area of active research. The results from this study are at …

The Effects Of Role-Playing On The Development Of Adaptive Skills In A Parent Training Program, Chantell A. Rodriguez-Del Valle

USF Tampa Graduate Theses and Dissertations

Parent training programs are widely used to remediate ineffective strategies being

used by parents of children with maladaptive behaviors. While there are a multitude of

parenting workshops available, it has been estimated that over half have no established

effectiveness. The purpose of this study was to advance our knowledge regarding the

effects of modeling and role-playing (in an experimentally controlled design), used to

supplement the parent workshop called “Winning at Parenting” and enhance development

of adaptive parenting skills of participants.

This study trained parents in the behavioral techniques of clear communication,

differential attention, and time-out procedures via modeling by the …

Assessment Of Image Analysis As A Measure Of Scleractinian Coral Growth, Steven K. Gustafson

USF Tampa Graduate Theses and Dissertations

Image analysis was used to measure basal areas of selected colonies of Montastraea annularis and Porites astreoides, following the colonies over a three-year period from 2002 to 2004. Existing digital images of permanently-marked quadrats in the Caye Caulker Marine Reserve, Belize, were selected based on image quality and availability of images of selected quadrats for all three years. Annual growth rates were calculated from the basal-area measurements. Mean growth rates (radial skeletal extension) for M. annularis and P. astreoides were 0.02 cm yr-1 and -0.20 cm yr-1, respectively. Basal area measurements demonstrated a large degree of variability. Increases were approximately …

On Modeling Hiv Infection Of Cd4+ T Cells, Amy Comerford

Electronic Theses and Dissertations

We examine an early model for the interaction of HIV with CD4+ T cells in vivo and define possible parameters and effects of said parameters on the model. We then examine a newer, more simplified model for the interaction of HIV with CD4+ T cells that also considers four populations: uninfected T cells, latently infected T cells, actively infected T cells, and free virus. The stability of both the disease free steady state and the endemically infected steady state are examined utilizing standard methods and the Routh-Hurwitz criteria. We show that if N, the number of infectious virions produced per …

Modeling The Influences Of Personality Preferences On The Selection Of Instructional Strategies Inintelligent Tutoring Systems, Robert Sottilare

Electronic Theses and Dissertations

This thesis hypothesizes that a method for selecting instructional strategies (specifically media) based in part on a relationship between learning style preference and personality preference provides more relevant and understandable feedback to students and thereby higher learning effectiveness. This research investigates whether personality preferences are valid predictors of learning style preferences. Since learning style preferences are a key consideration in instructional strategies and instructional strategies are a key consideration in learning effectiveness, this thesis contributes to a greater understanding of the relationship between personality preferences and effective learning in intelligent tutoring systems (ITS). This research attempts to contribute to the …

A Three-Dimensional Bay/Estuary Model To Simulate Water Quality Transport, Jing Yu

Electronic Theses and Dissertations

This thesis presents the development of a numerical water quality model using a general paradigm of reaction-based approaches. In a reaction-based approach, all conceptualized biogeochemical processes are transformed into a reaction network. Through the decomposition of species governing equations via Gauss-Jordan column reduction of the reaction network, (1) redundant fast reactions and irrelevant kinetic reactions are removed from the system, which alleviates the problem of unnecessary and erroneous formulation and parameterization of these reactions, and (2) fast reactions and slow reactions are decoupled, which enables robust numerical integrations. The system of species transport equations is transformed to reaction-extent transport equations, …

Computational Modeling Of Proton Exchange Membrane Electrolysis Cell For Hydrogen Production, Shanthi P Katukota

UNLV Retrospective Theses & Dissertations

Numerical simulations of electrochemical process for hydrogen production were performed for the purpose of examining the phenomena occurring within the proton exchange membrane (PEM) water splitting cell. A steady-state isothermal two dimensional model of the cell is developed. Finite element method was used to solve the multi-component transport model coupled with flow in porous medium, charge balance and electrochemical kinetics; Parametric studies were performed based on appropriate mass balances, transport, and electrochemical kinetics applied to the cell. It is observed that, as the water on the anode side flows from the inlet to the outlet, the mass fraction of oxygen …

Statistical Modeling Via Empirical Recurrence Rate, Hui Wang

UNLV Retrospective Theses & Dissertations

A key parameter, most sought after by the modelers of reliability, is the failure rate of a targeted repairable system. Popular modeling techniques based on a point process such as the Power-law process often are handicapped by the requirement of a monotonic failure rate. In this thesis, we show the potential of building a linking bridge between the traditional homogeneous and nonhomogeneous Poisson processes and the classical time series via a sequence of the empirical recurrence rates, calculated at equally spaced intervals of time. The distinctive signature, marking the unique failure pattern of a repairable system, is displayed with an …

Optimization For Finite Element Modeling Of Electronic Components Under Dynamic Loading, Srujanbabu Sridharala

UNLV Retrospective Theses & Dissertations

Usage of electronic components in the U.S. ARMY applications is becoming more challenging due to their usage in harsh environments. Experimental verification of these components is expensive and it can yield information about specific locations only. This research outlines the finite element modeling methodology for these electronic components that are subjected to high acceleration loads that occur over extremely short time such as impact, gun firing and blast events. Due to their miniature size these finite element models are computationally expensive. An optimization engine was presented to have an efficient analysis procedure that provides a combination of accuracy, computational speed …

Study Of Nanoscale Cmos Device And Circuit Reliability, Chuanzhao Yu

Electronic Theses and Dissertations

The development of semiconductor technology has led to the significant scaling of the transistor dimensions -The transistor gate length drops down to tens of nanometers and the gate oxide thickness to 1 nm. In the future several years, the deep submicron devices will dominate the semiconductor industry for the high transistor density and the corresponding performance enhancement. For these devices, the reliability issues are the first concern for the commercialization. The major reliability issues caused by voltage and/or temperature stress are gate oxide breakdown (BD), hot carrier effects (HCs), and negative bias temperature instability (NBTI). They become even more important …

Subband Adaptive Modeling Of Digital Hearing Aids, Michael Roy Wirtzfeld

Digitized Theses

In this thesis, the application of a subband adaptive model to characterize compression behaviour of five digital hearing aids is investigated. Using a signal-to-error ratio metric, modeling performance is determined by varying the number of analysis bands in the subband structure as well as consideration of three adaptive algorithms. The normalized least mean-squares (NLMS), the affine projection algorithm (APA), and the recursive least-squares (RLS) algorithms are employed using a range of parameters to determine the impact on modeling performance. Using the subband adaptive model to estimate the time-varying frequency response of each hearing aid allows the Perceptual Evaluation of Speech …

Predicting Anxiety From Parent And Childhood Variables, Brian Fisak

Electronic Theses and Dissertations

The high prevalence rate, significant distress and impairment, and persistence of childhood anxiety disorders highlight the need for continued theoretical conceptualization and research into the developmental pathways associated these disorders. In response to this need, one goal this project was to examination and identify variables associated with the development and/or maintenance of child anxiety disorders. A second goal of this project was to examine the potential role of learning from parents as a risk factor in the development of child anxiety, with a particular emphasis on three learning mechanisms: modeling, information transfer, and reinforcement of anxious behaviors. The third goal …

An Ahp Framework For Balancing Efficiency And Equity In The United States Liver Transplantation System, Vijayachandran M. Veerachandran

USF Tampa Graduate Theses and Dissertations

ABSRACT: Liver transplantation and allocation has been a controversial issue in the United States for decades. One of the main concerns in the allocation system is the trade-off between the two main objectives, efficiency and equity. Unfortunately, it is difficult to reach consensus on how to develop allocation policies that aim at balancing efficiency and equity, among transplantation policy makers, administrators, transplant surgeons and transplant candidates.Our research identifies and classifies the outcomes of liver allocation into two major categories, efficiency and equity, that are, often times, conflicting. Previous researchers did not consider how to balance outcomes in these two categories. …

Performance Modeling Of Explosively Actuated Devices, Adam M. Braud

LSU Master's Theses

Explosively actuated devices (pin pullers, cable cutters, valves, etc) are used extensively to perform critical functions for aerospace, industrial, and defense related applications. The failure of these devices have led to a greater effort to quantify device design and performance. This thesis describes the actuation process of an explosively actuated valve, including: 1) the burning of the solid explosive HMX (C₄H₈N₈O₈) and production of its high pressure gas products, 2) the mass transfer of gas products through an actuator to an expansion volume including choked flow effects, 3) the resulting piston motion …

Subband Adaptive Modeling Of Digital Hearing Aids, Michael Roy Wirtzfeld

Digitized Theses

ABSTRACT

In this thesis, the application of a subband adaptive model to characterize compression behaviour of five digital hearing aids is investigated. Using a signal-to-error ratio metric, modeling performance is determined by varying the number of analysis bands in the subband structure as well as consideration of three adaptive algorithms. The normalized least mean-squares (NLMS), the affine projection algorithm (APA), and the recursive least-squares (RLS) algorithms are employed using a range of parame­ters to determine the impact on modeling performance. Using the subband adaptive model to estimate the time-varying frequency response of each hearing aid allows the Perceptual Evaluation of …