Digital Commons Network^™

Correlating Simulated Surface Marks With Near-Surface Tornado Structure, Michael I. Zimmerman

Graduate Theses, Dissertations, and Problem Reports (ETD)

Tornadoes often leave behind patterns of debris deposition, or "surface marks", which provide a direct signature of their near surface winds. The intent of this thesis is to investigate what can be learned about near-surface tornado structure and intensity through the properties of surface marks generated by simulated, debris-laden tornadoes. Earlier work showed through numerical simulations that the tornado's structure and intensity is highly sensitive to properties of the near-surface flow and can change rapidly in time for some conditions. The strongest winds often occur within tens of meters of the surface where the threat to human life and property …

Simulation-Based Optimum Design Of Sensor Arrays Using Multi-Objective Tabu Search, Zongyu Geng

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis is concerned with the optimum design of sensor arrays (i.e., electronic noses or tongues) using simulation experiments. The proposed design method adopts a set of new criteria, which more adequately represent the desirable properties of a sensor array in practice. A number of best non-dominated array designs are selected through a multiple objective (criteria) Tabu search algorithm. The evaluation of a candidate sensor array is based on its multivariate calibration model, which is efficiently estimated from well-designed simulation experiments. The method can be used to optimize the design of both linear and nonlinear sensor arrays.

Cfd Applications In Airship Design, Kevin Shields

Graduate Theses, Dissertations, and Problem Reports (ETD)

This thesis examines the aerodynamic characteristics and flight dynamics of a lighter-than-air airship using analytical and computational fluid dynamics (CFD). Modern airships have frequently been proposed for military operations; one of which, designated YEZ-2A, was a prototype whose design was initiated during the 1980's. Designs were evaluated through the wind tunnel tests of a 1:75 scaled model performed by Gomes. His tests relied on surface roughening techniques to compensate for the inability to maintain Reynolds number similarity among scales.;Later, the scaled prototype would receive further attention during a CFD study at WVU. This study was undertaken to numerically simulate the …

Hardware, Software, And Low-Level Control Scheme Development For A Real-Time Autonomous Rover, Brenton K. Wilburn

Graduate Theses, Dissertations, and Problem Reports (ETD)

The objective of this research is to develop a low-cost autonomous rover platform for experiments in autonomous navigation. This thesis describes the design, development, and testing of an autonomous rover platform, based on the commercial, off-the-shelf Tamiya TXT-1 radio controlled vehicle. This vehicle is outfitted with an onboard computer based on the Mini-ITX architecture and an array of sensors for localization and obstacle avoidance, and programmed with Matlab/SimulinkRTM Real-Time Workshop (RTW) utilizing the Linux Real-Time Application Interface (RTAI) operating system.;First, a kinematic model is developed and verified for the rover. Then a proportional-integral-derivative (PID) feedback controller is developed for translational …

A Comprehensive Rocket And Radar Study Of Midlatitude Spread F, G.D. Earle, P. Bhaneja, P.A. Roddy, C.M. Swenson, A. Barjatya, R. L. Bishop, Et. Al

Publications

An instrumented sounding rocket launched from Wallops Island Virginia has flown through a midlatitude spread F (MSF) event in conjunction with simultaneous ionosonde, HF radar, and 244 MHz scintillation observations from the ground. The in situ measurements include the electric field, horizontal neutral wind, and plasma density within the spread F region. The ground‐based HF radar measurements of wave signatures in the bottomside F region ledge reveal the presence of waves propagating to the north and northwest prior to and during the spreading event. The periods of these bottomside waves range from 16 to 60 min, and they are shown …

Design And Implementation Of An Actively Adjustable Spring Mechanism Via Redundant Actuation, Eleazar Marquez

Theses and Dissertations - UTB/UTPA

This study presents the theoretical results and experimental validation of an adjustable stiffness mechanism. The use of redundant actuation is emphasized in the design of a one-degree-of-freedom Watt II mechanism capable of independently controlling the effective stiffness without a change in equilibrium position. This approach is in contrast to previous spring mechanism designs unable to actively control the spring rate independent of deflection, and has potential applications in various types of suspension and assembly systems. Results indicate that driving the redundantly actuated, unidirectional, spring mechanism requires attaching two direct brush-type direct current motors on each of the two grounded revolute …

Photolithographic Fabrication Of 3d Penrose-Like Quasi-Photonic Crystal Polymeric Templates Utilizing Lab-Made Phasemask, Faraon Torres-Lazos

Theses and Dissertations - UTB/UTPA

Photonic crystals (PhC) have recently become of great interest because of their potential as replacement of electronics and/or supplement to semiconductors technology. The PhC’s capability to make compact integrated optical circuits has already made possible the laboratory manufacture of an array of different types of optical waveguides, cavities and filters. The work presented here aimed to simultaneously fabricate a 3D-PhC templates employing six-beam holographic lithography. The basic procedures included recording gratings using interference field of laser sources in a photoresist coating on a glass substrate. The manufacturing method utilized only one optical element, a phasemask, drastically reducing the complexity of …

A Critical Analysis Of The Identification, Placement, And Assessment Policies For Achieving Educational Parity Of Bilingual Learners, Lilia Rocio Estrada

Theses and Dissertations - UTB/UTPA

This study analyzed the process of proper identification, placement, and assessment of Bilingual Learners (BLs) by investigating the perceptions of members in the Texas Language Proficiency Assessment Committee (LPAC). The findings focused on LPAC perceptions of their decisions to identify, place, and assess BLs as well as how these compared among members with different positions. Also, the LPAC members’ perceptions from schools that followed a dual language education program were compared to those schools that followed a transitional bilingual education program. It was found that majority of LPAC members lacked the confidence in assessing BLs, LPAC members holding higher positions …

Surface Optimization Of High Density Polyethylene And Carbon Nanofiber Composites For The Improvement Of Electromagnetic Shielding Effectiveness, Brandon C. Jarvis

Theses and Dissertations - UTB/UTPA

Nanoreinforced composites of High Density Polyethylene (HDPE) and Carbon Nanofibers (CNF) of varying nanofiber concentration were fabricated via melt mixing. Following fabrication, various metal and metal-nitride thin films were sputter deposited upon the substrates. Volume resistivity measurements of the composite substrates, as well as four point probe analysis of the composites and the deposited films were performed and are reported. Electromagnetic Interference (EMI) Shielding Effectiveness (SE) measurements were performed upon all samples in order to gauge the effects of percolation and the presence of the deposited film(s) upon overall SE. Comparisons of experimental measurements with analytical models available in the …

The Distribution And Comparative Biogeochemistry Of Silver With Other Selected Trace Metals In Coastal Waters Near Massachusetts, Usa, Christian F. Krahforst

Graduate Doctoral Dissertations

Water samples and hydrologic data were collected during 1994-1996 in New England coastal waters near Massachusetts, USA to examine the distribution of silver and other trace metals (Cu, Pb, Cd, Zn, and Fe) in the coastal systems of Massachusetts and Cape Cod Bays. These investigations were designed to test the hypothesis that silver could serve as a tracer of dispersion of municipal wastewater in Boston Harbor into Massachusetts and Cape Cod Bays and estimate the relative contribution of wastewater discharge to the overall silver budget of the Massachusetts Bays system. Silver concentrations in both particulate and filtered (<0.4 µm) fractions averaged 103 and 117 pmol kg-1 for Boston Harbor, 34 and 10 pmol kg-1 in western Massachusetts Bay, and 11 and 7 pmol kg-1 in the central portion of Massachusetts Bay, respectively. Average Ag concentrations in southern Gulf of Maine coastal waters were 10 and 2 pmol kg-1 for filtered and particulate fractions, respectively. While nearly half of the silver existed in particulate form in Boston Harbor, nearly 80% of the silver in Massachusetts and Cape Cod Bays occurred in the filterable fraction. Coastal water surveys revealed non-conservative Ag behavior and probably the result of incomplete mixing of three or more water masses with unique Ag signatures (e.g., Merrimack River, Boston Harbor, surface and intermediate Gulf of Maine waters). Quasi-steady state mass balance approaches estimate most of the silver entering into the Massachusetts Bays system during the study period was the result of municipal wastewater discharge to Boston Harbor (84-93%).

Multivariate analyses …

The Role Of Sulfur In Biomineralization: Argopecten Irradians And The Impact Of Ocean Acidification, Bryanna Joy Broadaway

Graduate Masters Theses

The burning of fossil fuels, and other natural processes, has led to an increase of carbon dioxide (CO₂) in the atmosphere. The equilibration of atmospheric CO₂ with surface waters causes the ocean pH to decrease from the current value of 8.1. Evidence suggests that as the ocean becomes more alkaline, organisms such as the bay scallop, Argopecten irradians¸will become more stressed due to increased energy demands to maintain shell deposition and growth. This stress, as hypothesized here, may cause the deposition of S-bearing organic macromolecules to aid in mineralization as well as the potential for sulfate …

2-D Path Planning For Direct Laser Deposition Process, Swathi Routhu, Divya Kanakanala, Jianzhong Ruan, Xiaoqing Frank Liu, Frank Liou

Computer Science Faculty Research & Creative Works

The zigzag and offset path have been the two most popular path patterns for tool movement in machining process. Different from the traditional machining processes, the quality of parts produced by the metal deposition process is much more dependent upon the choice of deposition paths. Due to the nature of the metal deposition processes, various tool path patterns not only change the efficiency but also affect the deposition height, a critical quality for metal deposition process. This paper presents the research conducted on calculating zigzag pattern to improve efficiency by minimizing the idle path. the deposition height is highly dependent …

Pot Heat Balance Analysis In Continuous Galvanizing Lines, Quang Minh Phuong

Graduate Theses, Dissertations, and Problem Reports (ETD)

Galvanizing is an energy intensive industry. Knowing how much energy is consumed when producing a certain product will help the company in determining which products can be produced to maximize profits. E-GEPDSS was built to explore the potential of saving energy in galvanizing lines by utilizing heat balance analysis. Heat transfer mechanisms of the heat losses for the pot presented in the heat balance are basic heat transfer concepts (i.e. radiation, convection, conduction, and specific heat.;The pot heat balance model was built and applied using the data collected from a host company during the plant visit. Sensitivity analyses were done …

A Comprehensive Simulation Model For Floating Gate Transistors, Steven Joseph Rapp

Graduate Theses, Dissertations, and Problem Reports (ETD)

Floating-gate transistors have proven to be extremely useful devices in the development of analog systems; however, the inability to properly simulate these devices has held back their adoption. The objective of this work was to develop a complete simulation model for a floating-gate (FG) MOSFET using both standard SPICE primitives and also MOSFET models taken directly from foundry characterizations. This new simulation model will give analog designers the ability simulate all aspects of floating-gate device operation including transient, AC and DC characteristics. This work describes the development of this model and demonstrates its use in various applications.

Three Essays On Caps Market And Unspanned Volatility, Harumi Hattori

Graduate Theses, Dissertations, and Problem Reports (ETD)

In this thesis we study the caps market. Caps are a contract where the interest rates are capped at some fixed value r¯. Caps consist of caplets which are European options on the forward rates called LIBOR (the London Inter-Bank Offer Rates). Caps are the derivatives of LIBOR. However, their relation is not so simple as the relation between a stock and its derivatives. One important difference is that the volatility in one market does not affect the volatility of the other market as much as in the stock and its derivative markets. This phenomenon is termed unspanned stochastic volatility …

Understanding Plasmas Through Ion Velocity Distribution Function Measurements, Saikat Chakraborty Thakur

Graduate Theses, Dissertations, and Problem Reports (ETD)

This work concerns measurements of ion velocity distribution functions (IVDF) using three different diagnostic techniques in expanding argon plasmas generated by two different helicon plasma sources. A theoretical prediction by Lieberman et al., of enhanced upstream ionization by electrons accelerating upstream, due to the formation of a stable electrostatic current-free double layer (DL) in an expanding plasma, was verified through laser induced fluorescence (LIF) and retarding field energy analyzer (RFEA) measurements of the IVDF and Langmuir probe measurements of the plasma density. Keeping all other external source parameters constant and varying only the operating frequency of the helicon source HELIX, …

Spectral Approaches To Natural Mesh Processing, Takamitsu Kawai

Graduate Theses, Dissertations, and Problem Reports (ETD)

Mesh design is a major bottleneck in the creation of computer games and animation. Therefore simplifying the process of mesh editing is an important problem. Natural mesh processing is generally difficult to perform since natural meshes often have nontrivial surface shapes and high degrees of freedom. In this study I present novel approaches to natural mesh processing utilizing spectral methods based on the manifold harmonic basis.;Geometric scaling transformations do not respect the biological processes which govern the size and shape of living creatures. I describe an approach to scaling which can be related to biological function. Known biological laws of …

High Rank Tensor And Spherical Harmonic Models For Diffusion Mri Processing, Inas A. Yassine

Graduate Theses, Dissertations, and Problem Reports (ETD)

Diffusion tensor imaging (DTI) is a non-invasive quantitative method of characterizing tissue micro-structure. Diffusion imaging attempts to characterize the manner by which the water molecules within a particular location move within a given amount of time. Measurement of the diffusion tensor (D) within a voxel allows a macroscopic voxel-averaged description of fiber structure, orientation and fully quantitative evaluation of the microstructural features of healthy and diseased tissue.;The rank two tensor model is incapable of resolving multiple fiber orientations within an individual voxel. This shortcoming of single tensor model stems from the fact that the tensor possesses only a single orientational …

Selective Self-Stereotyping And Women’S Self-Esteem Maintenance, Debra L. Oswald, Kristine M. Chapleau

Psychology Faculty Research and Publications

The process and implications of gender-based self-stereotyping are examined in this paper. Women displayed a tendency to selectively self-stereotype for personality and physical traits such that they endorsed positive stereotypic traits and denied negative traits as descriptive of the self and closest women friends. However, negative traits were endorsed as descriptive of women in general. Cognitive stereotypes were endorsed as more descriptive of all women than of the general university student. The tendency to selectively self-stereotype on physical traits was positively associated with appearance, social, and performance self-esteem. The results are discussed for their theoretical and practical implications.

Using Knowledge Building To Support Deep Learning, Collaboration And Innovation In Engineering Education, Glenn W. Ellis, Alan N. Rudnitsky, Mary A. Moriarty

Engineering: Faculty Publications

Knowledge building is a potentially transformative approach to engineering education. In knowledge building students participate in an interactive discourse in which they work together to broaden ideas, reform problems and share knowledge - the result being a deeper level of understanding and the collaborative production of new knowledge. In 2009 we conducted a knowledge building pilot study in the Picker Engineering Program at Smith College. In this study students worked together to formulate a question about the potential for a conscious machine and then engaged in an intensive knowledge building discourse. Assessment data showing the effectiveness of the approach and …

Normative Reflectance And Transmittance Measurements On Healthy Newborn And 1-Month-Old Infants, Gabrielle R. Merchant, Nicholas J. Horton, Susan E. Voss

Engineering: Faculty Publications

Objective:

Ear-canal-based wideband reflectance (WBR) measurements may provide objective measures to assess and monitor middle-ear status in young babies. This work presents WBR measurements of power reflectance and transmittance on populations of healthy newborn babies (3 to 5 days) and healthy 1-mo-old babies (28 to 34 days). Thus, this work determines how power reflectance and transmittance vary between newborn and 1-mo-old babies and characterizes the range of these measures in normal populations.

Design:

Power reflectance and transmittance were calculated from pressure measurements made in the ear canals of seven newborn (12 ears) and eleven 1-mo-old (19 ears) babies. Permutation tests, …

Examining The Effectiveness Of Dropout Prevention Practices And Their Implications For Intervention With Public School Students, Louisa Pollack

Dissertations

Schools face the dilemma of transforming both the trend of students dropping out of school and the associated negative socioeconomic outcomes into a positive path of persistence and school completion. Despite ongoing efforts of the federal and state government, as well as those of the local school districts, this problem continues to burden the educational system and society as a whole. The opinions of those with the experience of dropping out and returning to school are pertinent sources of information on educative practices that can help stem the dropout rate.

A survey was conducted to gather the opinions of students …

Emotional Maturity Of Adolescents And Adults In Ged Programs, Billy Joe Riffle

Dissertations

When discussing issues relating to students in General Educational Development (GED) Option and pre-GED programs with educators, the contention exists that it is possible to make reasonably accurate predictions on the success or failure of a student by observing a number of items. Looking at their cumulative records shows their academic and attendance history. Insight is gained by looking at their family dynamics and how they relate to adults. Much can be learned about them from their discipline reports and the nature of any infractions. One of the most intriguing aspects gained through experience and observation is the perception of …

The Relationship Between Leader Decision Making And Student Achievement At K-3 Title I And Reading First Elementary Schools, Emily Kathleen Richmond

Dissertations

This mixed methodology study investigated the relationship between administrator and teacher perceptions of leader decision making regarding five variables (reading training, reading curriculum, program evaluation, financial support, and student assessment) and student achievement (in the single content area, reading, at the 3rd grade level) in Title I K-3 schools receiving Reading First Grants (RFGs) and Title I K-3 schools not receiving RFGs, in four states (Arkansas, Georgia, Idaho, and Oklahoma). Respondent data and district data regarding percentages of students achieving proficient and above on state third grade reading assessments were analyzed via Pearson Correlations, Multiple Regression Analysis, and a MANOVA. …

Stereo Matching Using A Modified Efficient Belief Propagation In A Level Set Framework, Stephen Goyer Rogers

Dissertations

Stereo matching determines correspondence between pixels in two or more images of the same scene taken from different angles; this can be handled either locally or globally. The two most common global approaches are belief propagation (BP) and graph cuts.

Efficient belief propagation (EBP), which is the most widely used BP approach, uses a multi-scale message passing strategy, an O(k) smoothness cost algorithm, and a bipartite message passing strategy to speed up the convergence of the standard BP approach. As in standard belief propagation, every pixel sends messages to and receives messages from its four neighboring pixels in EBP. Each …

Folate Receptor-Targeted Delivery Of Small Interfering Rna To Cancer Cells, Yilin Zhang

Dissertations

The vitamin folic acid (folate, FA) has been extensively explored as a targeting ligand to deliver a variety of diagnostic/prognostic/therapeutic agents into various tumors through the assistance of its receptor – the folate receptor (FR). FR is over-expressed in many types of human cancer and can mediate internalization of FA-conjugates through an endocytic pathway. The discovery of small interfering RNA (siRNA), which is cable of inducing potent gene silencing in a sequence-specific manner, provides an excellent molecular tool to suppress aberrant gene expression in malignancies, and therefore siRNA has the potential to revolutionize cancer therapeutics. Towards the goal of developing …

The Effect Of A Math Emporium Course Redesign In Developmental And Introductory Mathematics Courses On Student Achievement And Students' Attitudes Toward Mathematics At A Two-Year College, Amy Renée Bishop

Dissertations

The purpose of this research was to determine the effect of computer-based instruction on student mathematics achievement and students' attitudes toward mathematics in developmental and introductory mathematics courses, namely Elementary Algebra, Intermediate Algebra, and College Algebra, at a community college. The researcher also examined the relationship between attitudes and achievement. The sample consisted of 112 students, and the study was conducted during the Spring 2010 semester at a community college in south Mississippi. The participants were enrolled in one of six classes taught by the researcher. The control group consisted of three classes (one Intermediate and two College Algebra sections) …

Study Of 3,3' Vs. 4,4' Dds Isomer Curatives On Physical Properties And Phenyl Ring Motions Of Dgeba Epoxy Via Molecular Dynamics, Deuterium Nmr, And Dielectric Spectroscopy, Samuel James Tucker

Dissertations

The purpose of this research is to develop a multiscale understanding of crosslinked amorphous matrices, connecting molecular level events to macroscopic properties. To accomplish this goal, our methodology was to identify network architectures that influence molecular level energy dissipation through mechanisms such as bond rotations, torsions, and ring flips and then relate those molecular motions to macroscopic properties. Studies were accomplished on two aerospace grade matrices: the epoxy, diglycidyl ether of bisphenol A (DGEBA) cured with two amines, 3,3’- diaminodiphenyl sulfone (33DDS) and 4,4’-diaminodiphenyl sulfone (44DDS). The 33DDS/DGEBA and 44DDS/DGEBA served both to provide a baseline for experimental testing of …

Synthesis And Electrical Properties Of Functional Block Copolymer/Inorganic Nanocomposite Materials, Hongying Chen

Dissertations

Sulfonated poly[styrene-b-ethylene-co-butylene-b-styrene] (sSEBS) block copolymers/inorganic nanocomposite materials were synthesized via in situ formation of inorganic fillers and characterized particularly for their dielectric properties and proton conductivities.

In preparation of sSEBS/SrTiO₃ nanocomposites, titanium (IV) isopropoxide [Ti(OPrⁱ)₄] complex was diffused into sSEBS film, followed by subsequent hydrolysis of [Ti(OPr i)4], diffusion of strontium cations in sSEBS domains, and in situ formation of crystalline SrTiO₃. sSEBS with sulfonation degree of 38.1% and 65.0% were employed, and relevant sSEBS/SrTiO₃ composites contain SrTiO₃ of 10-15 wt%. Elemental composition characterization with ESEM/EDX indicated uniform distribution of …

Bemdec: An Adaptive And Robust Methodology For Digital Image Feature Extraction, Isaac Kueth Gang

Dissertations

The intriguing study of feature extraction, and edge detection in particular, has, as a result of the increased use of imagery, drawn even more attention not just from the field of computer science but also from a variety of scientific fields. However, various challenges surrounding the formulation of feature extraction operator, particularly of edges, which is capable of satisfying the necessary properties of low probability of error (i.e., failure of marking true edges), accuracy, and consistent response to a single edge, continue to persist. Moreover, it should be pointed out that most of the work in the area of feature …