Partner
Collection
Serial/Series Title
The Eastman case studies
32
Corpus of News on the Web
21
Journal of Applied Rehabilitation Counseling
21
Music for Natural Trumpet
7
Corpus of Contemporary American English
3
Al Filo; no. 11
1
American Military Studies Series; no. 5
1
American Military Studies; no. 6
1
American Military Studies; no. 7
1
Corpus del Español
1
28 More
Degree Department
Department of Biological Sciences
63
College of Music
55
Department of Psychology
55
Department of English
45
Department of Counseling, Development and Higher Education
40
Department of Chemistry
39
Department of History
31
School of Visual Arts
27
Department of Computer Science
24
Department of Materials Science and Engineering
24
58 More
Degree Discipline
Degree Level
Country
States
Month
Language
887 Matching Results
Results open in a new window/tab.
Exploring EHR Adoption and Implementation: The Impact of Resource Advantage Theory on Healthcare Organization's Competitive Position
Access:
Use of this item is restricted to the UNT Community
The hospitals and their healthcare providers need to optimize simultaneously three outcomes: healthcare costs, healthcare options offered to customers, and information utilization efficiency. The adoption of electronic healthcare record (EHR) technologies is a potential managerial mechanism for balancing these outcomes. EHR offers patient management and decision support capabilities that can ameliorate health delivery outcomes for patients, doctors, and hospitals through better-informed business and care decisions. The analysis of data collected in an EHR system may lower costs and improve health care delivery (or both). In sum, it could be argued that EHR is a source of competitive advantage. Despite this prima facie appeal, many hospitals remain reluctant to adopt and implement EHR due to lack of insights into return on investment, unavailability of tested systems and data entry obstacles. To address this gap between the potential of EHR system and lack of its adoption, the purpose of this research is to investigate the role of EHR as a resource of competitive advantage for hospital. Essay 1, titled "Implementation and Adoption of EHR: A Conceptual Model based on Resource Advantage Theory", describes the antecedents and consequences of EHR adoption and implementation. Essay 2, titled "Exploring the Relationship Between Electronic Healthcare Record …
Date:
August 2019
Creator:
Malhan, Amit Sundeep
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Extrinsic Doping of Few Layered Tungsten Disulfide Films by Pulsed Laser Deposition
Access:
Use of this item is restricted to the UNT Community
This dissertation tested the hypothesis that pulsed laser deposition (PLD) could be used to create targeted dopant profiles in few layered WS2 films based on congruent evaporation of the target. At the growth temperatures used, 3D Volmer-Weber growth was observed. Increased energy transfer from the PLD plume to the growing films degraded stoichiometry (desorption of sulfur) and mobility. Sulfur vacancies act as donors and produce intrinsic n-type conductivity. Post deposition annealing significantly improved the crystallinity, which was accompanied by a mobility increase from 6.5 to 19.5 cm2/Vs. Preparation conditions that resulted in excess sulfur, possibly in the form of interstitials, resulted in p-type conductivity. Current-voltage studies indicated that Ohmic contacts were governed by surface properties and tunneling. Extrinsic p-type doping of few layered WS2 films with Nb via pulsed laser deposition using ablation targets fabricated from WS2, S and Nb powders is demonstrated. The undoped controls were n-type, and exhibited a Hall mobility of 0.4 cm2/Vs. Films doped at 0.5 and 1.1 atomic percentages niobium were p-type, and characterized by Fermi levels at 0.31 eV and 0.18 eV from the valence band edge. That is, the Fermi level moved closer to the valence band edge with increased doping. With increased …
Date:
August 2019
Creator:
Rathod, Urmilaben Pradipsinh P
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Faculty Characteristics and Program Budgets: Academic Capitalist Influences on Physical Therapy Graduate Outcomes
Access:
Use of this item is restricted to the UNT Community
This study sought to observe the trends in physical therapy faculty members over time and to understand how those trends correlated with changes in program outcomes. Accreditation data from 231 programs between 2008 and 2017 was used in a panel analysis using fixed effects and random effects models to estimate the effects that faculty characteristics, program characteristics, and program budgets have on graduation rates, first-time licensure examination pass rates, and the percentage of graduates of color that a program produced. Results show that for a 1% increase in faculty time devoted to scholarship, a program could expect graduation rates to rise by 0.17%. For a one percentage point increase in grant-funded faculty, a program could expect a 1.7% increase in graduation rates. Results also indicated a negative linear relationship between the number of publications and graduation rates. First-time licensure exam pass rates had an association with different variables. For a 1% increase in part-time faculty, a program could expect a 6.4% decline in first-time licensure examination pass rates. Similarly, a 1% increase in tenured faculty was associated with a 1.2% decline in first-time licensure examination pass rates. A 1% increase in faculty of color was associated with an increase in …
Date:
August 2019
Creator:
Dickson, Tara
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Geography of Retail Clinics Post Implementation of the Affordable Care Act
Access:
Use of this item is restricted to the UNT Community
Retail clinics are walk-in clinics designed for convenience and for servicing minor health issues and certain acute conditions. The model began as a way of bringing both convenience and care to areas that have lower levels of access to primary care resources. With the implementation of Affordable Care Act (ACA) in March 2010, populations that were previously uninsured were now required to have access to some level of health insurance. These populations presented a potential new market for retail clinics. This research shows that post implementation of the ACA, retail clinics tend to locate in areas with higher incomes and, generally, greater access to primary care.
Date:
August 2019
Creator:
Portillo, Ethan
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
A Global Spatial Model for Loop Pattern Fingerprints and Its Spectral Analysis
Access:
Use of this item is restricted to the UNT Community
The use of fingerprints for personal identification has been around for thousands of years (first established in ancient China and India). Fingerprint identification is based on two basic premises that the fingerprint is unique to an individual and the basic characteristics such as ridge pattern do not change over time. Despite extensive research, there are still mathematical challenges in characterization of fingerprints, matching and compression. We develop a new mathematical model in the spatial domain for globally modeling loop pattern fingerprints. Although it is based on the well-known AM-FM (amplitude modulation and frequency modulation) image representation, the model is constructed by a global mathematical function for the continuous phase and it provides a flexible parametric model for loop pattern fingerprints. In sharp contrast to the existing methods, we estimate spatial parameters from the spectral domain by combining the exact values of frequencies with their orientations perpendicular to the fingerprint ridge flow. In addition, to compress fingerprint images and test background Gaussian white noise, we propose a new method based on periodogram spacings. We obtain the joint pdf of these m-dependent random variables at Fourier frequencies and derive the asymptotic distribution of the test statistic.
Date:
August 2019
Creator:
Wu, Di
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
How the Conflict of Autonomous and Controlled Motivation Influences Sales Controls to Inside Sales Agents' Work Outcomes
Access:
Use of this item is restricted to the UNT Community
Through the use of multiple methodologies and analytical approaches, this dissertation combines (1) sales control; (2) call center service; and (3) motivational theory to extend sales control literature beyond its current state, to consider the conflicting motivational perspectives an inside sales agent has to experience. To achieve this unification, this dissertation consists of three essays intended to: (1) identify the influence of autonomous and controlled motivation on operational sales outcome controls and performance; (2) explore the influence these motivators have on sales controls and sales performance; and, (3) understand the impact of autonomous and controlled motivation on sales agent tenure.
Date:
August 2019
Creator:
Conde, Gonzalo R
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Impact of Property Tax Exemptions on the Fiscal Behavior of Cities: A Longitudinal Analysis of 41 Texas Cities
Access:
Use of this item is restricted to the UNT Community
As a form of tax and expenditure limitations, property tax exemptions result in an utility gap between two groups of population residing in the same community: free-riders who are paying less than they receive and contributors who are paying more than they receive. This utility gap is problematic to municipalities because contributors may exit the city as this gap becomes wider. How do municipalities respond to the increasing amount of property tax exemptions? Using 41 Texas cities data from 2000 to 2016, this dissertation examines how property tax exemptions affect municipalities' fiscal behavior. The analysis indicates that property tax exemptions lead to higher property tax burden, change municipalities' revenue structure, and lead to less capital spending.
Date:
August 2019
Creator:
Sun, Jingran
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Improving Actigraphy Specificity to Better Inform Insomnia Diagnosis and Treatment Decisions
Access:
Use of this item is restricted to the UNT Community
Accurate assessment of sleep-wake patterns is important for sleep researchers and clinicians. Actigraphs are low-cost, non-intrusive, wrist-worn activity detectors used to estimate sleep-wake patterns in a natural environment for several nights. Although actigraphy shows good sensitivity (sleep detection), it has consistently demonstrated poor specificity (wakefulness detection while lying in bed relatively motionless). Because insomnia is characterized by wakefulness in bed, actigraphy may not be a valid objective measure of wakefulness for this group. It is possible that refinement of actigraphy software settings for sleep/wake algorithms might improve specificity. The current studies investigated this hypothesis by comparing wake parameters from 48 combinations of actigraphy settings to determine which sleep/wake algorithms best inform insomnia diagnosis and treatment. In the first study, none of the 48 actigraphy setting combinations consistently discriminated between adults with insomnia (n = 69) and non-insomnia (n = 80) on all three wake parameters, and no setting clearly discriminated between groups for the composite variable, total wake time. Similarly, in the second study, no setting combinations consistently discriminated between adults treated for insomnia (n = 18) and controls with untreated insomnia (n = 26) on all three wake parameters. Although two setting combinations discriminated between groups for the composite …
Date:
August 2019
Creator:
Francetich, Jade Marie
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
John La Montaine's "Songs of the Rose of Sharon" and "Fragments from the Song of Songs": A Socio-Historical Analysis and Performer's Guide
Access:
Use of this item is restricted to the UNT Community
The purpose of this research is to examine John La Montaine's only two song cycles for soprano and orchestra, Songs of the Rose of Sharon, opus 6 (1947) and Fragments from the Song of Songs, opus 29 (1959). In this investigation-the first ever specific to these works-I examine the works and cultural context in which they were created. I then evaluate the reasonable possibility that La Montaine used his public platform as a composer and performer to subtly celebrate taboo themes of feminism, sexuality, and blackness while shining a light on human injustice. Through close examination of social and historical context, I argue two points. Firstly, Rose of Sharon and Fragments are landmark American works. They are anomalies in classical music history in that a white male heralds texts about a black woman in an unlikely time in American history, thus arguably becoming an unlikely part of the evolution of African-American women in artistic endeavors. Secondly, in the performance guide, I advocate that these works would readily adapt to a staged performance. I discuss how La Montaine's musical settings illustrate the inherent drama of the text, provide a context for interpreting the protagonist in Rose of Sharon and Fragments, and …
Date:
August 2019
Creator:
Dapcic, Samantha
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Ligand Effects in Gold(I) Acyclic Diaminocarbene Complexes and Their Influence on Regio- and Enantioselectivity of Homogeneous Gold(I) Catalysis
Access:
Use of this item is restricted to the UNT Community
This dissertation focuses on the computational investigation of gold(I) acyclic diaminocarbene (ADC) complexes and their application in homogeneous gold(I) catalysis. Chapter 2 is an in-depth computational investigation of the σ- and π-bonding interactions that make up the gold-carbene bond. Due to the inherent conformation flexibility of ADC ligands, distortions of the carbene plane can arise that disrupt orbital overlap between the lone pairs on the adjacent nitrogen atoms and the empty p-orbital of the carbene. This study investigated the affect these distortions have on the strength of the σ- and π-bonding interactions. This investigation demonstrated that while these distortions can affect the σ- and π-bonding interactions, the ADC ligand have to become highly distorted before any significant change in energy of either the σ- or π-bonding interactions occurs. Chapter 3 is a collaborative investigation between experimental and computational methods, DFT calculations were employed to support the experimental catalytic results and determine the role that steric effects have in controlling the regioselectivity of a long-standing electronically controlled gold(I)-catalyzed tandem 1,6-enyne cyclization/hydroarylation reaction with indole. This study demonstrated that by sterically hindering nucleophilic attack of indole at the favored position, nucleophilic attack would occur at a secondary position leading to the selective …
Date:
August 2019
Creator:
Ellison, Matthew Christopher
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Linking Enhanced Fatigue Life to Design by Modifying the Microstructure
Access:
Use of this item is restricted to the UNT Community
Structural material fatigue is a leading cause of failure and has motivated fatigue-resistant design to eliminate risks to human lives. Intrinsic microstructural features alter fatigue deformation mechanisms so profoundly that, essentially, fatigue properties of structural materials become deviant. With this in mind, we initiated this project to investigate the microstructural effect on fatigue behavior of potential structural high entropy alloys. With a better understanding of the effect of microstructure features on fatigue properties, the ultimate goal was to engineer the microstructure to enhance the fatigue life of structural materials. The effects of two major deformation mechanisms presented here are twinning-induced fatigue crack retardation, and transformation-induced fatigue crack retardation. The fundamental principle of both mechanisms is to delay the fatigue crack propagation rate by altering the work hardening ability locally within the crack plastic zone. In ultrafine grained triplex Al0.3CoCrFeNi, nano-sized deformation twins were observed during cyclic loading in FCC matrix due to low stacking fault energy (SFE). The work-hardening ability of the material near the crack was sustained with the formation of twins according to Considere's criteria. Further, due to the ultrafine-grained (UFG) nature of the material, fatigue runout stress was enhanced. In a coarse-grained, dual-phase high entropy alloy, persistent …
Date:
August 2019
Creator:
Liu, Kaimiao
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Lookouts
Access:
Use of this item is restricted to the UNT Community
Lookouts follows Matt and Joann, two fire tower lookouts for the United States Forest Service, as they discuss their happiness living in seclusion as well as the decline of fire towers due to technological advances.
Date:
August 2019
Creator:
Dejarnett, Claire
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Luigi Boccherini's Cello Concerto in B-Flat Major, G.482: Creating a Performance Edition through a Critical Study of the 'Original' Version and Friedrich Grützmacher's Edition
Access:
Use of this item is restricted to the UNT Community
The Cello Concerto in B-flat major, G.482, by Italian composer Luigi Boccherini (1743-1805), is the composer's most beloved work for the instrument, as well as one of the most performed pieces in the Classical concerto repertoire. Historically, cellists performing this work have used an edition prepared by German cellist Friedrich Grützmacher (1832-1903). However, an 'original' version that was discovered in 1949 is significantly different from that of Grützmacher. A comparison of both editions has revealed that Grützmacher in fact made considerable modifications to Boccherini's 'original.' Along with the issue of having two editions, cellists that have played the 'original' edition have noted that there are certain practical and interpretative matters that are not favorable to the cellist, particularly in terms of the way the music is notated and how it lacks many details. This dissertation provides clarity to these issues by undertaking a comprehensive analysis of both editions in order to make cellists become aware of the differences between both editions by comparing musical elements from a performance practice viewpoint. In addition, I discuss relevant issues that are present in the 'original' version, ultimately providing an alternative performance edition to this score that is based on historically informed performance (HIP) …
Date:
August 2019
Creator:
Cho, Hyun Mi
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Measurement of Positive Continuance Intention Drivers within a Service Domain
Access:
Use of this item is restricted to the UNT Community
The contribution of this dissertation is how model measurement allows examination of the balance between what is practical in terms of consumer concerns versus what is optimal in terms of cost control. Essay 1 examines a research framework that incorporates various service recovery strategies and simultaneously evaluates their comparative influences. Essay 2 evaluates the complex interrelationships among different factors related to the post-complaint behavioral process. Essay 3 fills a research gap by examining the role of brand equity by operationalizing a reflective model using PLS in operations management (OM) research. These three essays provide insight into the quality management domain and the value that is achieved via a data driven examination of theory. Moreover, this research will provide operations management practitioners a basis to carry out future research on quality management phenomena as well as insight into how to balance cost control and service recovery strategies with the goal of achieving a competitive advantage.
Date:
August 2019
Creator:
Harun, Md Ahasan Uddin
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Metabolic Physiology of Planarian Flatworms
Access:
Use of this item is restricted to the UNT Community
Using a high throughput closed respirometry method to measure oxygen consumption, I determined metabolic rates in asexual and sexual Schmidtea mediterranea and Girardia dorotocephala, as a function of temperature, taxon, stressors, reproductive mode, age, regeneration, and specific dynamic action. This study has shown that oxygen consumption can reliably be measured in planaria using optode closed respirometry, and also provided a reliable method for measuring wet mass in planaria, which has been a challenge to researchers in the past. This research revealed that oxygen consumption in S. mediterranea is 1.5-2.1X greater in the sexual strain over the asexual strain at 13-18°C. Within the sexual strain, oxygen consumption is 1.5 -2.2X greater in sexually mature adults over the sexually immature groups (hatchlings, juveniles, and regenerating sexuals). Furthermore, I was able to quantify differences in sexual morphology between these groups exhibiting significant differences in oxygen consumption. The results of this research supports a theory of higher metabolic costs with sexual maturity in S. mediterranea. Therefore, this study has established sexual and asexual S. mediterranea as simple, yet attractive models for investigating energetic costs between sexual and asexual phenotypes. This research also provided quantitative values for specific dynamic action in planaria, with a maximum …
Date:
August 2019
Creator:
Lewallen, Melissa A
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Method Development for Corrosion Testing of Carbon Steel and Ni-based Alloy Coatings Exposed to Gas Hydrate Formation Environments
Access:
Use of this item is restricted to the UNT Community
Gas hydrate formation and corrosion can cause serious safety and flow assurance problems in subsea environments. One aspect that has been given less attention is the corrosion behavior of materials in gas hydrate formation environment (GHFE). This work introduces a new technique/method for corrosion testing of materials exposed to low temperatures GHFEs. This technique allows pH monitoring, and control of test conditions like temperature. In this work, GHFE is defined as an environment that includes water, methanol and its degraded products in the presence of corrosive agents like CO2 and chloride salt at gas hydrate formation temperatures (GHFT). After 20 hrs immersion in CO2-saturated salinity environment at GHFT, as-deposited Ni-Mo alloy coating has the highest corrosion resistance of 33.28 kΩ cm2. The corrosion resistance dropped to 14.36 kΩ cm2 and 11.11 kΩ cm2 in the sweet low-salinity and sweet high-salinity test solutions respectively. The combined results of SEM/EDX showed that the Ni-Mo coating oxide layer broke down quicker in sweet high-salinity environment than sweet low-salinity environment. When carbon steel was immersed in a CO2-saturated high salinity environment at GHFT, there was slight overall change in corrosion rate (CR) as salt concentration increase from 3 wt% to 25 wt%. In degraded …
Date:
August 2019
Creator:
Ozigagu, Christopher E.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Military and Veteran Mental Health Stigma and Help-Seeking Behaviors: Role of Leadership and Attachment
Access:
Use of this item is restricted to the UNT Community
Mental health stigma has been identified as a barrier to help-seeking in the United States. Research suggests that insecure attachment may contribute to higher mental health stigma and lower help-seeking behavior. This may be particularly salient in military personnel who tend to report higher mental health stigma than the general population. Evidence suggests that both supportive and destructive military leadership are related to service members' attitudes toward seeking help. In the current study, a sample of military service members and veterans (N = 232) completed an online survey regarding mental health stigma, military leadership experiences, attachment strategies, and mental health help-seeking behaviors. Findings indicated that destructive and supportive leadership experiences were significantly related to self and public stigma, and self-stigma mediated the relationship between destructive and supportive leadership experiences and likelihood to seek help. Attachment anxiety predicted higher self and public stigma, while attachment avoidance predicted high self-stigma but low public stigma, with high self-stigma partially mediating the relationship between attachment avoidance and help seeking.
Date:
August 2019
Creator:
McGuffin, James
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Mining Biomedical Data for Hidden Relationship Discovery
Access:
Use of this item is restricted to the UNT Community
With an ever-growing number of publications in the biomedical domain, it becomes likely that important implicit connections between individual concepts of biomedical knowledge are overlooked. Literature based discovery (LBD) is in practice for many years to identify plausible associations between previously unrelated concepts. In this paper, we present a new, completely automatic and interactive system that creates a graph-based knowledge base to capture multifaceted complex associations among biomedical concepts. For a given pair of input concepts, our system auto-generates a list of ranked subgraphs uncovering possible previously unnoticed associations based on context information. To rank these subgraphs, we implement a novel ranking method using the context information obtained by performing random walks on the graph. In addition, we enhance the system by training a Neural Network Classifier to output the likelihood of the two concepts being likely related, which provides better insights to the end user.
Date:
August 2019
Creator:
Dharmavaram, Sirisha
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
A Novel Two-Stage Adaptive Method for Estimating Large Covariance and Precision Matrices
Access:
Use of this item is restricted to the UNT Community
Estimating large covariance and precision (inverse covariance) matrices has become increasingly important in high dimensional statistics because of its wide applications. The estimation problem is challenging not only theoretically due to the constraint of its positive definiteness, but also computationally because of the curse of dimensionality. Many types of estimators have been proposed such as thresholding under the sparsity assumption of the target matrix, banding and tapering the sample covariance matrix. However, these estimators are not always guaranteed to be positive-definite, especially, for finite samples, and the sparsity assumption is rather restrictive. We propose a novel two-stage adaptive method based on the Cholesky decomposition of a general covariance matrix. By banding the precision matrix in the first stage and adapting the estimates to the second stage estimation, we develop a computationally efficient and statistically accurate method for estimating high dimensional precision matrices. We demonstrate the finite-sample performance of the proposed method by simulations from autoregressive, moving average, and long-range dependent processes. We illustrate its wide applicability by analyzing financial data such S&P 500 index and IBM stock returns, and electric power consumption of individual households. The theoretical properties of the proposed method are also investigated within a large class of …
Date:
August 2019
Creator:
Rajendran, Rajanikanth
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Optimizing Production System Maintenance Policies when Cyber Threats are Considered
Access:
Use of this item is restricted to the UNT Community
In a production environment, physical and cyber-related failures become unavoidable because of the complexity of highly connected manufacturing systems and a finite equipment life cycle. The main purpose of this thesis is to investigate optimal maintenance outsourcing and replacement policies in the presence of cyber-threats, as well as policies to achieve channel coordination via cost subsidization. Although well-developed maintenance outsourcing literature has addressed many advanced and trending issues such as the costs and benefits of new technology adoptions, learning effects, forgetting effects, and systems with back-up machines, no study has looked at the effect of cyber threats on connected production systems. Besides filling this gap, this thesis addresses the most common replacement policies including preventive maintenance with minimal repairs and age replacement. The advent of the Internet of Things (IoT) has enabled the creation of "smart" manufacturing systems, However the resulting connected format makes these systems potential targets for cyber-attacks. Manufacturers have to face a difficult decision as to whether they should adopt costly security technologies or let the manufacturing systems be vulnerable to cyber-threats. This study develops a model addressing this dilemma by providing some insights into the effects of cost subsidization and installation of security systems on the …
Date:
August 2019
Creator:
Ta, Anh V
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Phase Transformation and Elastic Constants in Binary Titanium Alloys: An Atomistic Study
Access:
Use of this item is restricted to the UNT Community
The current understanding of the mechanical properties and deformation behavior of some individual phases in titanium alloys is limited due to the fine scale at which these phases precipitate within the β-phase matrix. The α and ω phases represent the most widely observed phases in titanium alloys depending on the alloy composition and also the heat treatment procedure adopted during processing. The possibility of precipitating ω-phase depends on the content of the β-stabilizers within the system. Although a significant compositional partitioning occurs within ω-phase upon aging treatment, the knowledge of ω-phase mechanical properties as a function of composition is very limited. The initial part of the current work focuses on the effect of common β-stabilizers elements on the phase stability and mechanical properties of the ω-phase using first-principles calculations. A relation between the bonding nature, the phase stability, and elastic properties was proposed. Thereafter αʺ martensitic phase was investigated in Ti-Nb and Ti-Nb-O alloys. The phase stability and martensitic start temperature of αʺ-phase was studied as a function of Nb and oxygen content. Also, the effect of the lattice shear distortion induced by oxygen atom on stabilizing β-phase was investigated. Subsequently the effect of the β-stabilizers' elements on stacking faults …
Date:
August 2019
Creator:
Salloom, Riyadh Farooq
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Phase Transformations in Refractory High Entropy Alloys
Access:
Use of this item is restricted to the UNT Community
High entropy alloys (HEAs) based on refractory elements have shown a great potential for high temperature structural applications. In particular, the ones containing Al, exhibits a microstructure similar to the γ-γ' in Ni-based superalloys. While these alloys exhibit impressive strengths at room temperature (RT) and at elevated temperatures, the continuous B2 matrix in these alloys is likely to be responsible for their brittle behavior at RT. Phase stability of five such alloys are studied by thermo-mechanical treatments and characterization techniques using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Two of these alloys showed an inverted microstructure, where the disordered BCC phase becomes continuous, and therefore, they were characterized in detail using SEM, TEM, atom probe tomography (APT) and synchrotron x-ray diffraction experiments. The phenomenon of phase inversion lead to a better combination of strength and ductility as compared to the non-inverted microstructure.To enhance the stability of B2 intermetallic phase which provides the strength when present in a BCC matrix, multicomponent B2 phase compositions stable at 1000°C in some of the above studied alloys, were melted separately. The aim was to establish a single phase B2 at 1000°C and understand the mechanical behavior of these single-phase multicomponent B2 intermetallic …
Date:
August 2019
Creator:
Soni, Vishal
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Prevalence and Proportionality of Dyslexia in Texas Public and Charter School Districts
Access:
Use of this item is restricted to the UNT Community
Passed in 1985, the Texas Education Code (TEC) §38.003, Screening and Treatment of Dyslexia and Related Disorders, required public school districts and charters to identify and provide remediation services for students with dyslexia. While Texas was the first state to pass such a requirement, the question remains: What is the prevalence and proportionality of dyslexia in Texas public school districts and charters? In Phase 1 of this study, a secondary analysis using point prevalence and disproportionality calculations was conducted to analyze the impact of this more than 30-year-old law. In order to better help understand these findings, semi-structured interviews with district leaders were conducted in Phase 2 to gain insight on how students were identified with dyslexia across the state. The results of Phase 1 showed the estimated prevalence of dyslexia in Texas public school districts and charters to be low in comparison to the literature. Additionally, the findings suggested a discrepancy in identifications between gender and district type (public school versus charter) and across racial and ethnic groups. Meanwhile, the results of Phase 2 revealed that leadership, support, funding, and accountability impact dyslexia identifications. This study emphasizes the need to further explore and analyze how to best identify and …
Date:
August 2019
Creator:
Sneed, Samantha
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Processing-Structure-Property Relationships of Reactive Spark Plasma Sintered Boron Carbide-Titanium Diboride Composites
Access:
Use of this item is restricted to the UNT Community
Sintering parameter effects on the microstructure of boron carbide and boron carbide/titanium diboride composites are investigated. The resulting microstructure and composition are characterized by scanning electron microscopy (SEM), x-ray microscopy (XRM) and x-ray diffraction (XRD). Starting powder size distribution effects on microstructure are present and effect the mechanical properties. Reactive spark plasma sintering introduces boron nitride (BN) intergranular films (IGF's) and their effects on fracture toughness, hardness and flexural strength are shown. Mechanical testing of Vickers hardness, 3-point bend and Chevron notch was done and the microstructural effects on the resulting mechanical properties are investigated.
Date:
August 2019
Creator:
Lide, Hunter
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library