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899 Matching Results

Start Over Decade 2020-2029 Month December Language English

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Results: 1 - 24 of 899 next

(open access)

2021 State of the Fleet Report

Report over the Texas State Vehicle Fleet Management Plan, which identifies standard processes for establishing the appropriate number and type of state-operated vehicles and provides guidelines to maximize fleet use and maintain efficiency.

Date: December 2020

Creator: Texas. Comptroller's Office.

Object Type: Report

System: The Portal to Texas History

3D Printing of Zinc Anode for Zinc Ion Batteries

Recently, 3D printing has received increasing attention for the fabrication and assembly of electrodes for batteries due to the freedom of creating structures in any shape or size, porosity, flexibility, stretchability, and chemistry. Particularly, zinc ion batteries (ZIBs) are favored due to high safety, cheap materials cost, and high volumetric capacity (5,849 mAh/cm3), however, rapid evaporation of Zn due to low melting temperature has limited its 3D printability via conventional laser-based additive manufacturing technique. Here, we develop a printable ink for the fabrication of flexible and 3D printed Zn anode with varied surface areas using the direct ink writing (DIW) method. Our 3D printed porous and high surface area Zn anode structures effectively suppressed the dendrite growth while providing high Zn ion diffusion towards the cathode to significantly enhance the performance of ZIB. By varying filament distancing and path, we 3D printed zinc anode structures with different active surface areas, surface area to volume ratio, porosity, flexible and multiple layer structures that can be incorporated on any device. Carbon in the composite improved conductivity, and mechanical stability of 3D printed zinc anode. Our 3D printed composite anodes allowed flexible designing of batteries surpassing conventional battery designs such as coin cells …

Date: December 2021

Creator: Amoko, Stephen Adot Oyo

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Acenaphthene and 1,10-Phenanthroline-Fused Βeta-Functionalized Porphyrins

A series of acene-fused porphyrins and 1,10-phenanthroline-fused porphyrins were synthesized and characterized via NMR spectroscopy and mass spectrometry. The acene-fused porphyrins exhibit unique optoelectronic properties, most notably they exhibit highly red-shifted absorption bands. The 1,10-phenanthroline-fused porphyrins are of interest for their ability to bond to as variety of metals to form chelation complexes.

Date: December 2023

Creator: Arvidson, Jacob Randall

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Acute and Sublethal Impacts of Crude Oil Photo-Induced Toxicity in an Early Life Stage Marine Fish (Sciaenops ocellatus) and Invertebrate (Americamysis bahia)

We investigated the modifying effects of ultraviolet (UV) light and chemical dispersant (Corexit 9500A) on crude oil toxicity in juvenile mysids (≤ 24 h) (Americamysis bahia) and larval red drum (24-72 hpf) (Sciaenops ocellatus). These results demonstrate that crude oil toxicity significantly increases with co-exposure to environmentally relevant UV levels in both species, indicating photo-induced toxicity. This toxicity was further exacerbated by the application of chemical dispersants which increased the dissolution and concentration of oil-derived polycyclic aromatic hydrocarbons (PAHs) in test solutions. To better understand the mechanisms and initiating events of this observed photo-induced toxicity, the incidence of apoptotic cell death and global transcriptomic changes were assessed in larval red drum (24-72 hpf) following co-exposure to crude oil and UV. These results showed that co-exposure to UV and low concentrations of crude oil (<1 µg/L ∑PAH50) induced apoptotic cell death in skin and eye tissue and altered transcriptomic pathways related to visual processing and dermatological disease. To link these cellular and molecular impacts of photo-induced toxicity to apical endpoints of ecological performance, sublethal impacts to growth, metabolic rate, and visually mediated behaviors were explored in larval red drum at 2 developmental stages. These results suggested that earlier life stages may …

Date: December 2023

Creator: Leads, Rachel Renee

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Adaptation and Validation of the Athletic Identity Measurement Scale for Use with Musicians

Identity is a powerful concept that influences behavior and health. For over thirty years, researchers in sport psychology have been using the Athletic Identity Measurement Scale (AIMS) as a research instrument providing insights into the relationships between athletic identity and health variables. While musician identity is recognized as an important factor to be investigated in relation to occupational health, there are no known robust instruments like the AIMS in music psychology research. The current study aimed to adapt and validate the athletic identity measurement scale for use with musicians. The AIMS history includes episodes of modifications for performance enhancement of the instrument that resulted in five different models. The validation process includes evaluating the psychometrical properties across all five models. The sample included student musicians and non-student musicians (N = 1040). The traditional confirmatory factor analysis (CFA) and the maximum likelihood (ML) estimation method were used. The exploratory structural equation modeling (ESEM) and robust weighted least squares (WLS) was utilized to explore a new method of estimation that was known to resolve issues consistent with the CFA and ML method. The goodness-of-fit indices of CFA and ESEM were compared. The results showed that the MIMS is a reliable and valid …

Date: December 2022

Creator: Zuhdi, Nabeel

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Adaptive learning: toward an intentional model for learning process guidance based on learner’s motivation

Article describes how, the goal of ITS is to support learning content, activities, and resources, adapted to the specific needs of the individual learner and influenced by learner’s motivation. This research proposes an intentional model that adopts Map formalism to support personalized learning guidance by considering learner’s motivation.

Date: December 5, 2022

Creator: Bayounes, Walid; Saâdi, Bayoudh Ines & Kinshuk

Object Type: Article

System: The UNT Digital Library

Additive Friction Stir Deposition of Al-Ce Alloys for Improved Strength and Ductility

Additive friction stir deposition (AFSD) is a solid-state additive manufacturing (AM) technique that breaks down large constituent particles into more refined and uniformly disturbed microstructure. AFSD was used to print Al-Ce alloys. Current commercial Al-alloys upon elevated temperatures go through dissolution and coarsening of strengthening precipitates causing mechanical degradation of these alloys. Al-Ce alloys do not have this issue as cerium's low solubility restricts dissolution into the aluminum matrix at elevated temperatures, thus giving great thermal stability to the microstructure. Al-Ce alloys lack solid solubility that affects the solid solution strengthening and precipitation strengthening. Al-Ce alloys have limitation at room temperature as they can only reach a maximum of ~65 MPa yield strength. Elements like magnesium have been added to alloy to enable solid solution strengthening, and scandium to enable precipitation strengthening to improve strength before going through the AFSD process. By adding new elements to the Al-Ce alloys, an increase in the yield strength from ~60 MPa to ~200 MPa was achieved before AFSD. The casted alloys form coarse particles that reach 300 µm in size; resulting in stress concentration that causes material fracture before necking, giving >10% ductility. AFSD breaks down these coarse particles to increase strength and …

Date: December 2023

Creator: Davis, Devin Fredric

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Additive Manufacturing of AZ31B Magnesium Alloy via Friction Stir Deposition

Additive friction stir deposition (AFSD) of AZ31B magnesium alloy was conducted to examine evolution of grain structure, phases, and crystallographic texture. AFSD was carried out using a hollow tool made from tool steel at a constant rotational velocity of 400 rpm on the AZ31B base plate. Bar stock of AZ31B was utilized as a feed material. The linear velocity of the tool was varied in the range of 4.2-6.3 mm/s. The feed rate of the material had to be maintained at a half value compared to the corresponding linear velocity for the successful deposition. The layer thickness and length of the deposits were kept constant at 1 mm and 50 mm respectively. The tool torque and actuator force values were recorded during the process and for calculation of the average input energy for each processing condition. Temperature during the AFSD experiments was monitored using a type k thermocouple located 4 mm beneath the deposition surface at the center of the deposition track. The average input energy values showed a decreasing trend with increasing tool linear velocity. The temperature values during deposition were ∼0.7 times the liquidus of the alloy. The deposited material then was examined by laser microscope and profilometer, …

Date: December 2021

Creator: Patil, Shreyash Manojkumar

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Adoption of Credit-Hour Reductions in Master of Divinity Programs at the Association of Theological Schools Member Institutions: An Event History Analysis

Seminaries in the United States have for more than two centuries sought to equip ministerial leaders for service within the community of faith. And yet these institutions have traditionally been the focus of very little quantitative research. This lack of data is particularly noteworthy given the existential crises many seminaries currently face, especially regarding their flagship Master of Divinity (MDiv) programs. Among seminary leadership, a common response to declining MDiv enrollment has been to decrease the length of the program, which historically required at least 90 credit hours. The purpose of this quantitative study was to explore change at the Association of Theological Schools member institutions (AMIs) between 2000–2019 through the lens of these credit-hour reductions. Longitudinal data from 113 AMIs were analyzed to examine the relationship between a variety of financial, enrollment, and institutional characteristics and the likelihood that an AMI would reduce its required MDiv credit hours. Results from an event history analysis revealed that, all else being equal, experiencing an increase in total revenues reduced an AMI's likelihood of making a reduction, while being a middle-age institution (founded 1870–1959) and having a higher percentage of peer institutions that made a change increased the likelihood of making a …

Date: December 2021

Creator: McKanna, Nathan Jay

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Adult Attachment, Perceived Social Support, and Problematic Video Gaming Behavior

With the growing popularity in video games, there has been increased concerns over the prolonged exposure to the entertainment medium. Problematic gaming is defined as a pattern of gaming behavior that causes significant impairment in personal, social, other important areas of functioning, often characterized by preoccupation and loss of interest in other areas. This study examined how problematic gaming behaviors may be influenced by insecure adult attachment and perceived social support from differing sources. It was hypothesized that avoidant attachment would have a significant direct and indirect effect (via perceived social support) on problematic gaming. In addition, perceived social support from online friends and from offline friends were hypothesized to moderate the relationship between attachment and problematic gaming, Participants were recruited from both SONA (n = 151) and Amazon's Mturk (n = 264) to complete an online research questionnaire that measured variables of interest. Results indicated that the direct and indirect effects of attachment avoidance on problematic gaming were supported in both subsamples but the moderator effects were not. Further exploratory analysis found that anxious attachment demonstrated a similar pattern as avoidant attachment, but with a significant moderator effect of perceived social support from online friends (enhance) on the attachment …

Date: December 2020

Creator: Gu, Peter

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Advanced Cathodes for High Energy Density Lithium Sulfur Battery

A systematic development of 2D alloy catalyst with synergistic performance of high lithium polysulfide (LiPS) binding energy and efficient Li+ ion/electron conduction is presented. The first section of work found that Li+ ions can flow through the percolated ion transport pathway in polycrystalline MoS2, while Na+ and K+ ions can easily flow through the percolated 1D ion channel near the grain boundaries. An unusually high ionic conductivity of extrinsic Li+, Na+, and K+ ions in 2D MoS2 film exceeding 1 S/cm was measured that is more than two orders of magnitude higher than those of conventional solid ionic materials, including 2D ionic materials. The second section of this dissertation focus on catalyzing the transformation of LiPSs to prevent the shuttle effect during the battery cycling by synthesizing 2H (semiconducting) – 1T (metallic) mixed phase 2D Mo0.5W0.5S2 alloy on CNF paper, using two step sputtering and sulfurization method. The lithium sulfur (Li-S) battery cell assembled with the 2D Mo0.5W0.5S2/CNF/S cathode shows a high specific capacity of 1228 mAh g-1 at 0.1C and much higher cyclic stability over 4 times as compared to the pristine cathodes. The high LiPSs binding energy of catalyst efficiently prevents the shuttling effect and corrosion of Li …

Date: December 2021

Creator: Bhoyate, Sanket

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Advancing Reverse Electrowetting-on-Dielectric from Planar to Rough Surface Electrodes for High Power Density Energy Harvesting

Article presenting electrical and multiphysics-based modeling approaches of REWOD energy harvester using structured rough surface electrodes. By enhancing the overall available surface area, an increase in the overall capacitance is achieved.

Date: December 15, 2021

Creator: Adhikari, Pashupati R.; Patwary, Adnan B.; Kakaraparty, Karthik; Gunti, Avinash; Reid, Russell C. & Mahbub, Ifana

Object Type: Article

System: The UNT Digital Library

Aerodynamic Optimization of a 2D Airfoil for Rotary-Wing Aircraft at Mars Atmospheric Conditions

The interest toward Mars exploration has been considerably increasing due to also the successful deployment of the Perseverance rover and the continuous tests developed by SpaceX's launch vehicle, Starship. While the Mars 2020 mission is currently in progress, the first controlled flight on another planet have been proven in April 2021 with the vertical take-off and landing of the Ingenuity rotorcraft on Mars. In addition, the rotorcraft Dragonfly is expected to achieve the same endeavor in Titan, the largest moon of Saturn, by 2036. Continuous efforts have been oriented toward the development of new technologies and aircraft configurations to improve the performance of current proposed designs to achieve powered flight in different planetary bodies. This thesis work is a preliminary study to develop a comprehensive analysis over the generation of optimum airfoil geometries to achieve vertical flight in environments where low Reynolds numbers and Mach number equal to 0.2 and 0.5.

Date: December 2021

Creator: Saez, Aleandro G.

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Agile Practices in Data Science and Data Analytics Projects: A Research Agenda

The digital age comes with transformational activities (also referred to as digital transformation) triggered by emerging fields and technologies, such as data science and analytics, cybersecurity, cloud computing, blockchain, cryptocurrency, and nanotechnology; helping organizations stay current and competitive. This paper focuses on agile frameworks that support the delivery of data science/analytics projects to ensure organizations rapidly deliver analytics products and services to their customers.

Date: December 2020

Creator: Atolagbe-Olaoye, Abidemi

Object Type: Paper

System: The UNT Digital Library

(open access)

Aging Texas Well Strategic Plan: 2022 - 2023

Strategic plan for the Aging Texas Well program outlining priorities and strategies for addressing them. The goal of the plan is to help older Texans and their informal caregivers plan for the future while providing community and state leadership with recommendations and guidance for establishing policies and the infrastructure to support healthy aging for all Texans.

Date: December 2021

Creator: Texas Health and Human Services Commission

Object Type: Report

System: The Portal to Texas History

(open access)

Air Corridors: Concept, Design, Simulation, and Rules of Engagement

Air corridors are an integral part of the advanced air mobility infrastructure. They are the virtual highways in the sky for transportation of people and cargo in the controlled airspace at an altitude of around 1000 ft. to 2000 ft. above the ground level. This paper presents fundamental insights into the design of air corridors with high operational efficiency as well as zero collisions. It begins with the definitions of air cube, skylane or track, intersection, vertiport, gate, and air corridor. Then, a multi-layered air corridor model is proposed. Traffic at intersections is analyzed in detail with examples of vehicles turning in different directions. The concept of capacity of an air corridor is introduced along with the nature of distribution of locations of vehicles in the air corridor and collision probability inside the corridor are discussed. Finally, the results of simulations of traffic flows are presented.

Date: December 2021

Creator: Muna, Sabrina Islam

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

Alexandria Ocasio-Cortez: Media Coverage of Age, Gender, and Ethnicity in the 116th Congress

This study focuses on Alexandria Ocasio-Cortez, the U.S. Representative for New York's 14th Congressional District, and how news media portray her based on her gender, age, and ethnicity, which still play essential roles in the political system in the United States. The analysis of previous academic research, newspaper articles from the New York Times and the Washington Post (June 1, 2018 to June 30, 2019) and framing and feminist theories are used to evaluate coverage of Alexandria Ocasio-Cortez. The newspaper stories are examined based on the framing of traits including being the youngest woman ever elected to Congress, being Latina, and being one the most progressive politicians in the Congress. The main objective of this study is to shed light on a topic that at this moment in time is more relevant than ever because the 116th Congress has the highest number of women and women of color in U.S. history. I examine media coverage that Rep. Alexandria Ocasio-Cortez receives for stereotypical frames, so that, overall, all women running or holding public office may receive unbiased and more balanced media coverage. This study also intends to hold media outlets accountable for the way they portray different candidates because it has …

Date: December 2020

Creator: Reyes, Blanca Elena

Object Type: Thesis or Dissertation

System: The UNT Digital Library

Algebraic Trait for Structurally Balanced Property of Node and Its Applications in System Behaviors

This thesis targets at providing an algebraic method to indicate network behaviors. Furthermore, for a signed-average consensus problem of the system behaviors, event-triggering signed-average algorithms are designed to reduce the communication overheads. In Chapter 1, the background is introduced, and the problem is formulated. In Chapter 2, notations and basics of graph theory are presented. It is known that the terminal value of the system state is determined by the initial state, left eigenvector and right eigenvector associated with zero eigenvalue of the Laplacian matrix. Since there is no mathematical expression of right eigenvector, in Chapter 3, mathematical expression of right eigenvector is given. In Chapter 4, algebraic trait for structurally balanced property of a node is proposed. In Chapter 5, a method for characterization of collective behaviors under directed signed networks is developed. In Chapter 6, dynamic event-triggering signed-average algorithms are proposed and proved for the purpose of relieving the communication burden between agents. Chapter 7 summarizes the thesis and gives future directions.

Date: December 2021

Creator: Du, Wen (Electrical engineering researcher)

Object Type: Thesis or Dissertation

System: The UNT Digital Library

(open access)

All Texas Access Report

Report providing information about progress on programs to improve mental health services in rural Texas. This update "focuses on jail diversion and communiy integration as central themes in coordinated care that can significantly impact the four strategies [identified by regional groups]. Each rural-serving [local mental health authority]or [local behavioral health authority] choses [sic] a strategy within the theme that would best meet the needs of their local community, with 17 of the 30 having a funding source for implementation" (p. 1).

Date: December 2022

Creator: Texas Health and Human Services Commission

Object Type: Report

System: The Portal to Texas History

(open access)

The allometric propagation of COVID-19 is explained by human travel

Article develops an allometric model capable of fitting the initial phase of the COVID-19 pandemic and predicting the propagation of the illness for up to 100 days.

Date: December 18, 2021

Creator: Tuladhar, Rohisha; Grigolini, Paolo & Santamaria, Fidel

Object Type: Article

System: The UNT Digital Library

Alterations in the Expression of Proteins Associated with Non-Alcoholic Fatty Liver Disease Observed in the Liver of the C57Bl/6 Wild-Type Male Mouse in Response to Exposure of Mixed Vehicle Emissions and/or High Fat Diet Consumption

Recent epidemiological studies have demonstrated a correlation between the manifestation of non-alcoholic fatty liver disease (NAFLD) and ambient air pollution levels, which is exacerbated by the presence of other risk factors, such as diabetes, dyslipidemia, obesity, and hypertension. We investigated the hypothesis that exposure to a mixture of gasoline and diesel engine emissions (MVE) coupled with the concurrent consumption of a high-fat (HF) diet promotes the development of a NAFLD phenotype within the liver. Three-month-old male C57Bl/6 mice were placed on either a low fat or HF diet and exposed via whole-body inhalation to either filtered (FA) air or MVE (30 µg PM/m3 gasoline engine emissions + 70 µg PM/m3 diesel engine emissions) 6 hr/day for 30 days. Histology revealed mild microvesicular steatosis and hepatocyte hypertrophy in response to MVE exposure alone, compared to FA controls, yielding a classification of "borderline NASH" under the criteria of the modified NAFLD active score (NAS) system. As anticipated, animals on a HF diet exhibited moderate steatosis; however, we also observed inflammatory infiltrates, hepatocyte hypertrophy, and increased lipid accumulation, with the combined effect of HF diet and MVE exposure. Immunofluorescence staining and RT-qPCR of the liver revealed the presence of lipid peroxidation, altered expression …

Date: December 2022

Creator: Schneider, Leah Jayne

Object Type: Thesis or Dissertation

System: The UNT Digital Library