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UNT Theses and Dissertations
411
UNT Scholarly Works
56
Photographing Texas
46
Journal of Near-Death Studies
18
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Texas Pano Project
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Journal of Near-Death Studies
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JNDS, Volume 39, Number 3
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Southwest Retort
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JNDS, Volume 39, Number 2
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South Texas Catholic
5
JNDS, Volume 39, Number 1
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Al Filo; no. 11
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American Military Studies Series; no. 5
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30
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Degree Level
Year
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Computational Studies of the Photophysical, Structural, and Catalytic Properties of Complex Chemical Systems
Computational chemistry employs mathematical algorithms, statistics, and large databases to integrate chemical theory with experimental observations. Computational modeling allows us to make predictions concerning molecular properties and reactivity that ultimately lead to accurate assessment of the most important fundamental properties of chemical systems. Advances in theoretical techniques and computer power have dramatically increased the usefulness and importance of computational chemistry as a complement to experimental studies. This is especially relevant to catalytic reactions of industrial importance as well as the analysis of structural properties and the resulting spectroscopic phenomena in what are often otherwise counterintuitive models. This dissertation is a representation of the research I performed during my years as a graduate student in the Chemistry Department at the University of North Texas. My research has examined novel carbenes as efficient organocatalysts, structure-based design and optimization of small molecule drugs, and surveying methods to accurately describe structure and bonding and catalytic abilities of inorganic and organometallic systems. The works presented herein have been published or are awaiting submission to peer-reviewed scientific journals. A variety of computational techniques were employed in studying metal-mediated catalysis and organocatalysis as well as the structural and photophysical properties of systems containing closed-shell transition metal ions.
Date:
May 2021
Creator:
Melancon, Kortney
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Computational Techniques for Accelerated Materials Discovery
Increasing ubiquity of computational resources has enabled simulation of complex electronic systems and modern materials. The PAOFLOW software package is a tool designed to construct and analyze tight binding Hamiltonians from the solutions of DFT calculations. PAOFLOW leverages localized basis sets to greatly reduce computational costs of post-processing QE simulation results, enabling efficient determination of properties such as electronic density, band structures in the presence of electric or magnetic fields, magnetic or spin circular dichroism, spin-texture, Fermi surfaces, spin or anomalous Hall conductivity (SHC or AHC), electronic transport, and more. PAOFLOW's broad functionality is detailed in this work, and several independent studies where PAOFLOW's capabilities directly enabled research on promising candidates for ferroelectric and spintronic based technologies are described. Today, Quantum computers are at the forefront of computational information science. Materials scientists and quantum chemists can use quantum computers to simulate interacting systems of fermions, without having to perform the iterative methods of classical computing. This dissertation also describes a study where the band structure for silicon is simulated for the first time on quantum hardware and broadens this concept for simulating band structures of generic crystalline structures on quantum machines.
Date:
December 2021
Creator:
Cerasoli, Franklin
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Construct Validity of the I-SIP and Its Clinical Utility in Differentiating between Factitious Psychological Presentations (FPPs) and Malingering
Forensic researchers and practitioners continue to face challenges when attempting to differentiate deceptive response styles, notably when comparing malingering and factitious disorder. However, due to the great disparities in research available, forensic examiners may not be adequately informed for considering factitious presentations as a competing hypothesis to malingering. De-emphasis of factitious disorders may also be attributed to the lack of empirical research and poor conceptual understanding of the disorder. Velsor and Rogers conducted a thorough review of various factitious motivations, drawing a parallel to Rogers' explanatory models of malingering. Due to the need for a systematic measure of FPPs, the Inventory of Self and Interpersonal Problems (I-SIP) was developed, largely based on the explanatory models of FPP. The current study employed a construct validity approach to the I-SIP to examine its convergent and discriminant validity in a sample of 80 inpatients from a private psychiatric hospital. Providing strong evidence of construct validity of the I-SIP, dramatic differences emerged between malingered and factitious presentations with extremely large effect sizes (ds = 1.09 – 3.62). In particular, results indicated strong support for the nurturance explanatory model of FPPs, as over-investment in treatment providers was an especially strong discriminator (d = 3.62). Moreover, …
Date:
August 2021
Creator:
Velsor, Sarah Frances
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Continuing the Work of Our Ancestors: Black Radical Leadership and Disruptive Pedagogies in Affirming the Well-being of Black Students
Using Black feminist thought and BlackCrit/critical race theory frameworks, this qualitative study examined Black educators' practices in addressing the behavior of their students in an urban school district. It utilized counternarratives and storytelling to explore the cultural dynamics at play between Black educators and their Black students. The Black educators in this study operated under several behavior systems, including positive behavioral interventions and supports (PBIS), socio-emotional learning (SEL), restorative practices (RPs), and zero tolerance policies (ZTPs). Such systems have been implemented based on research that they have the capacity to train Black students to make appropriate decisions regarding their behavior. These systems are also reinforced under the notion that they create learning spaces which promote academic achievement. Due to their own experiences and understanding about how institutional practices and disciplinary interventions result disproportionately in oppression and violence against Black students, these educators disrupted these practices and utilized cultural approaches that centered Black-ness. In doing so, they were able to address behavior and affirm Black students' well-being. The cultural approaches conceptualized as disruptive pedagogies include aspects of othermothering, otherfathering, critical caring, sermonizing, womanist caring, and Black masculine caring. An analysis of the stories and counternarratives illustrated that Black principals, counselors, and …
Date:
May 2021
Creator:
Foster, Marquita Delorse
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Contradictory Attitudes towards Partisan Issues: Abortion and Gun Control
In this study, I examine how self-reported religiosity predicts political opinion toward abortion and gun control. In particular, I examine how self-reported religiosity relates to individuals' inconsistent attitudes on these two issues where liberal attitudes are held toward one issue, but conservative attitudes are held toward the other. Most commonly, these inconsistent attitudes are found among individuals who hold pro-life (conservative) and pro-gun control (liberal) views. Using data from the 2018 General Social Survey, I find that religiosity significantly predicts these inconsistent attitudes regarding abortion and gun control. This suggests that religious ethics regarding life and death can offer a partial explanation for inconsistent attitudes toward partisan issues.
Date:
December 2021
Creator:
Pinney, Sarah
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Convolutional Recurrent Structure in Computer Vision Applications
By organically fusing the methods of convolutional neural network (CNN) and recurrent neural network (RNN), this dissertation focuses on the application of optical character recognition and image classification processing. The first part of this dissertation presents an end-to-end novel receipt recognition system for capturing effective information from receipts (CEIR). The main contributions of this research part are divided into three parts. First, this research develops a preprocessing method for receipt images. Second, the modified connectionist text proposal network is introduced to execute text detection. Third, the CEIR combines the convolutional recurrent neural network with the connectionist temporal classification with maximum entropy regularization as a loss function to update the weights in networks and extract the characters from receipt. The CEIR system is validated with the scanned receipts optical character recognition and information extraction (SROIE) database. Furthermore, the CEIR system has strong robustness and can be extended to a variety of different scenarios beyond receipts. For the convolutional recurrent structure application of land use image classification, this dissertation comes up with a novel deep learning model for land use classification, the convolutional recurrent land use classifier (CRLUC), which further improves the accuracy in classifying remote sensing land use images. Besides, the …
Date:
December 2021
Creator:
Xie, Dong
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Correspondence between Receptive and Expressive Task Performances: A Further Analysis of Necessary Conditions
This study was a replication and an extension of the 2021 research performed by Spurgin and Borquez on the correspondence between receptive and expressive behavior. Spurgin examined the role of the echoic in a hear-say procedure with adult learners, while Borquez examined the role of the echoic in both hear-say and see-say procedures. Both studies found that receptive and expressive correspondence did not occur consistently across participants. The present study asked if the fading steps used during training contributed to the results of the previous researchers. In the present study, the fading steps were changed to minimize the chance that the participant developed a position bias. The conditions were also counterbalanced to analyze the effects of hear-say vs. see-say, easy vs. difficult words, and the order in which the words were trained on the acquisition of receptive labels and the emergence of expressive labels. The study consisted of five phases: pre-training, hear-say teaching, see-say teaching, receptive testing, and expressive testing. Results indicated that although that acquisition of receptive labels improved, the change in fading steps did not make a significant difference in the correspondence of receptive and expressive language. Results showed similar correspondence in the hear-say and see-say procedures. Easy …
Date:
December 2021
Creator:
Nachawati, Noor
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Corrosion Mechanism and Prevention of Wire Bonded Device in Microelectronic Manufacturing and Spectroscopic Investigation of Copper Etch Chemical Equilibria for High Density Interconnect Application
In the first part of this dissertation work, Al bond pad corrosion behavior was investigated in the presence of common industrial contaminants such as chloride (Cl-) and fluoride (F-). Al corrosion while in direct contact with Cu displayed rapid hydrogen (H2) gas evolution and dendrite propagation. In contrast, Al without bimetallic contact showed only minor surface roughening. This observed difference in the corrosion mechanism between Cl- and F- is attributed to the solubility of the corrosion products (AlCl3 vs. AlF3) formed on the Al surface. Our subsequent work explored corrosion prevention inhibition of wire-bonded devices (WBD) in the Cl- environment. Our research shows that the Al bond pad was protected against corrosion by chemically modifying the surface of the Cu wires, thereby preventing the H2 evolution. The inhibitor was observed to be highly selective, thermally stable, hydrophobic, and cost-effective, making it viable for industrial application of this coating for Al bond pad corrosion prevention. In the second part of the dissertation work, we utilized a novel approach of using ultraviolet-visible spectroscopy (UV-Vis) as a chemical-sensitive monitoring tool of the chemical environment in Cu etch bath. The UV-Vis technique illuminates the roles of H+, Cl-, Cu+, and Cu2+ to the etch …
Date:
December 2021
Creator:
Ashok Kumar, Goutham Issac
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Counselors' Experiences of HIV Status Disclosure to Children Living with HIV in Uganda
Reports from the World Health Organization (WHO) indicate tremendous advancement in the fight against HIV/AIDS infection through prevention, provision of high-quality treatment options, and psychosocial services to infected and affected individuals and communities. However, there is still a considerable number of new infections occurring among children, especially in sub-Saharan Africa. Researchers highlight the benefits of HIV status disclosure to children. Yet, there is limited research concerning the ways counselors navigate the process of status disclosure to children with an HIV diagnosis. The purpose of this study was to examine the experiences of counselors regarding status disclosure to children living with HIV in Uganda, and to determine their self-identified training needs. I utilized a phenomenological qualitative research method and conducted individual interviews using a semi-structured interview protocol with 10 counselors from three HIV care centers in the central region of Uganda. Findings indicated six overarching themes including: (1) counselors' roles and responsibilities, (2) impact of age in the disclosure process, (3) motivations for disclosure, (4) challenges and barriers, (5) counselor preparations and trainings for disclosure, (6) and post-disclosure interventions. Study results highlight the critical role played by counselors during the HIV status disclosure process and the need for additional training and …
Date:
August 2021
Creator:
Opondo, Harriet
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Counting Plane Tropical Curves via Lattice Paths in Polygons
A projective plane tropical curve is a proper immersion of a graph into the real Cartesian plane subject to some conditions such as that the images of all the edges must be lines with rational slopes. Two important combinatorial invariants of a projective plane tropical curve are its degree, d, and genus g. First, we explore Gathmann and Markwig's approach to the study of the moduli spaces of such curves and explain their proof that the number of projective plane tropical curves, counting multiplicity, passing through n = 3d + g -1 points does not depend on the choice of points, provided they are in tropical general position. This number of curves is called a Gromov-Written invariant. Second, we discuss the proof of a theorem of Mikhalkin that allows one to compute the Gromov-Written invariant by a purely combinatorial process of counting certain lattice paths.
Date:
December 2021
Creator:
Zhang, Yingyu
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
COVID-19 Diagnosis and Segmentation Using Machine Learning Analyses of Lung Computerized Tomography
COVID-19 is a highly contagious and virulent disease caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). COVID-19 disease induces lung changes observed in lung computerized tomography (CT) and the percentage of those diseased areas on the CT correlates with the severity of the disease. Therefore, segmentation of CT images to delineate the diseased or lesioned areas is a logical first step to quantify disease severity, which will help physicians predict disease prognosis and guide early treatments to deliver more positive patient outcomes. It is crucial to develop an automated analysis of CT images to save their time and efforts. This dissertation proposes CoviNet, a deep three-dimensional convolutional neural network (3D-CNN) to diagnose COVID-19 in CT images. It also proposes CoviNet Enhanced, a hybrid approach with 3D-CNN and support vector machines. It also proposes CoviSegNet and CoviSegNet Enhanced, which are enhanced U-Net models to segment ground-glass opacities and consolidations observed in computerized tomography (CT) images of COVID-19 patients. We trained and tested the proposed approaches using several public datasets of CT images. The experimental results show the proposed methods are highly effective for COVID-19 detection and segmentation and exhibit better accuracy, precision, sensitivity, specificity, F-1 score, Matthew's correlation coefficient (MCC), dice …
Date:
August 2021
Creator:
Mittal, Bhuvan
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Creating a Local Usage Collection System: PySUSHI
Presentation discussing the design and implementation of a built-in-house usage collection system for electronic resource usage via release 4 and release 5 of the SUSHI protocol, as well as the design and integration of additional modules for the loading of manually downloaded COUNTER reports.
Date:
2021-11-01/2021-11-04
Creator:
Hergert, Christopher; Harker, Karen & Byrne, Sephra
Object Type:
Presentation
System:
The UNT Digital Library
Creating a Public Pedagogy for Anti-Rape Activism: How We Learn to Advocate for Others
This thesis explores the way we learn to advocate for sexual assault survivors. This multi-methodological, qualitative study examines both popular cultural representations of sexual assault and official training materials provided by rape crisis centers and domestic violence organizations as sites of pedagogical messaging. I argue that it is imperative to incorporate intersectional feminist frameworks into understanding how advocacy is animated in these different sites of learning. This project offers an intersectional feminist analysis of two television shows: Netflix's Unbelievable and HBO's I May Destroy You, in addition to the Texas Association Against Sexual Assault (TAASA) training manual and supplemental training materials from six different rape crisis centers within a 75-mile radius of the Dallas Ft. Worth metroplex. Together, both sets of texts work pedagogically to teach us who is a worthy victim, what counts as "real" rape (and to challenge this very framework), and who deserves organizational resources. This thesis concludes by offering an Intersectional Rape Advocacy Toolkit, aimed at offering a set of values, lessons, and practices necessary for activists to grow in mutual advocacy for survivors and mutual support for fellow activists working to put an end to rape culture.
Date:
August 2021
Creator:
Garcia, Kayleigh Elaine
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Credentialing in Higher Education: A User Experience Study of the University of North Texas' Student Learner Record
This was a mixed-method user-centered study regarding the University of North Texas's student-owned learner record and credentialing system. Through methods of quantitative and qualitative inquiry, student perceptions were unearthed and recommendations to improve the system were provided.
Date:
December 2021
Creator:
Stutts, Sarah
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Criminology Collection Evaluation Report
This report summarizes an evaluation of the UNT Libraries' Criminology collection to determine if the collection is adequately serving patron needs. It was determined that the collection was currently meeting patrons' needs, and some recommendations for future collection maintenance were included.
Date:
November 15, 2021
Creator:
Harker, Karen
Object Type:
Report
System:
The UNT Digital Library
Crying for Change: Examining the Use of Period Melodrama and the Melodramatic Mode in Contemporary Queer Representation
This thesis illustrates how Melodrama and the melodramatic mode have been adapted within contemporary cinema as both a means of commenting on prior LGBTQI representation, and of exposing mainstream audiences to the issues still faced by many within this spectrum. Through my analyses of Carol (2015), Brokeback Mountain (2005), and A Single Man (2009), I examine how filmmakers have drawn on Melodrama as both an aesthetic form, and as a reference to the broader field of generic history and criticism which ground it as a subversive form of societal critique. By focusing specifically on how these three films portray ideological issues of gender, stereotyping, parenthood, aging, and personal shame, my thesis argues that these films are making a commentary on the damaging effects of these discourses on broader society. I also simultaneously question whether the Period Melodrama as a genre can ever fully escape the conservative nature of this form, as well as the implications of continuing to portray those on the LGBTQI spectrum as victims.
Date:
August 2021
Creator:
Bonthuys, Justin
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Crystallization and Lithium Ion Diffusion Mechanism in the Lithium-Aluminum-Germanium-Phosphate Glass-Ceramic Solid Electrolytes
NASCION-type lithium-aluminum-germanium-phosphate (LAGP) glass-ceramic is one of the most promising solid electrolyte (SEs) material for the next generation Li-ion battery. Based on the crystallization of glass-ceramic material, the two-step heat treatment was designed to control the crystallization of Li-ion conducting crystal in the glass matrix. The results show that the LAGP crystal is preferred to internally crystalize, Tg + 60%∆T is the nucleation temperature that provides the highest ion conductivity. The compositional investigation also found that, pure LAGP crystal phase can be synthesized by lowering the amount of GeO2. To fill gap of atomic structure in LAGP glass-ceramic, molecular dynamic (MD) simulation was used to build the crystal, glass, and interfacial structure LAGP. The aliovalent ion substitution induced an simultaneously redistribution of Li to the 36f interstitial site, and the rapid cooperative motion between the Li-ions at 36f can drop the activation energy of LAGP crystal by decreasing the relaxation energy; furthermore, an energy model was built based on the time-based analysis of Li-ion diffusion to articulate the behavior. The glass and interfacial structure show and accumulation of AlO4, GeO4 and Li at the interface, which explains the Li-trapping on the intergranular glass phase. An in-situ synchrotron X-ray study found …
Date:
May 2021
Creator:
Kuo, Po Hsuen
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Czech Opera Arias: An Anthology for Soprano
This anthology of late 19th- and early 20th-century Czech opera arias for soprano focuses on works that lack existing scholarship, bridging the language gap through translations and pronunciation materials for English-speaking singers. Its 24 arias supplement the works of Smetana, Dvořák, and Janáček with those of contemporaneous composers Karel Bendl, Zdeněk Fibich, Josef Bohuslav Foerster, Karel Kovařovic, Vítězslav Novák, and Otakar Ostrčil. Its musicological scope provides vignettes of the musical-cultural landscape of Czech opera around the turn of the 20th century, the transformation of Czech declamation during that period, and the language knowledge needed to sing the works thereof. Chapter 2 elucidates the methodology used in the anthology's phonetic transcriptions and discusses the unique articulatory demands of singing in Czech. Chapter 3 grounds contemporaneous discussion of Czech declamation as late 19th- and early 20th-century composers and librettists sought to shape a musical voice suited to the features of their language. The following chapter is a look at Janáček's unique solution to this challenge. In Chapter 5, the relationship between criticism and composition is examined for these two faces of Czech modernism. Finally, Chapter 6 includes new performance editions of the arias curated for the anthology. Each aria is accompanied by …
Date:
May 2021
Creator:
Nichols, Brittany "Bree"
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
The Decolonization of United States History: Exploring American Exceptionalism
Like many institutions of high education throughout the United States, the University of North Texas requires all students to pass introductory United States History courses. While the purpose of these courses should be to create a population well versed in U.S. history and sociopolitical and economic context, the foundational textbooks utilized in these courses promote American exceptionalism and U.S. supremacy. Their omission of the complex and controversial history of the United States creates a false master narrative based on an idealized version of U.S. history. Even textbooks that include diversity continue to uphold a progressive master narrative that ignores issues of systemic racism, sexism, and homophobia. My theoretical analysis of the required textbooks, Exploring American Histories: A Survey with Sources, is applicable to all introductory U.S. history textbooks. Decolonialism, critical race, and intersectional feminism are theoretical lenses that disentangle and highlight otherwise invisible aspects of American exceptionalism and the serious consequences of the subjugation of subaltern historical narratives. This thesis applies theory with examples of how textbooks or supplemental teaching can expose foundational oppression, violence, and discrimination to teach students critical thinking and help them see connections between the past and their present.
Date:
May 2021
Creator:
Walsh, Leah Sydney Pearce
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Deep Minima and Vortices for Positronium Formation in Positron-Hydrogen and Positron-Helium Collisions
This dissertation work is a study of positronium formation for positron-hydrogen and positron-helium collisions in the Ore gap (the energy region between the threshold for ground-state positronium formation and the first excitation level of the target atom) using variational K-matrices. We have fitted the K-matrices using multichannel effective range theories and using polynomials. Using the variational K-matrices and their fits, we have located zeros in the positronium-formation scattering amplitude and corresponding deep minima in the positronium-formation differential cross section. The zeros are related to the vortices in the extended velocity field associated with the positronium-formation scattering amplitude. For positron-hydrogen collisions, we have found two zeros in the positronium-formation scattering amplitude, and corresponding deep minima in the positronium-formation differential cross section, while we have obtained a zero in the positronium-formation scattering amplitude for positron-helium collisions. We have connected the zeros in the positronium-formation scattering amplitude to vortices in the extended velocity fields. Our work shows that vortices can occur for charge exchange in atomic collisions.
Date:
May 2021
Creator:
Alrowaily, Albandari Wanes
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Defect-Engineered Two-Dimensional Transition Metal Dichalcogenides for High-Efficient Piezoelectric Sensor
Piezoelectricity in two-dimensional (2D) transition metal dichalcogenides (TMDs) has attracted significant attention due to their unique crystal structure and the lack of inversion centers when the bulk TMDs thin down to monolayer. Although the piezoelectricity effect in atomic-thickness TMDs has been demonstrated, they are not scalable. Herein, we demonstrate a piezoelectric effect from large-scale, sputtered MoS2 and WS2 using a robust defect-engineering based on the thermal-solvent annealing and solvent immersion process. This yields a higher piezoelectric output over 20 times after annealing or solvent immersion. Indeed, the piezoelectric responses are strengthened with the increases of defect density. Moreover, the MoS2 or WS2 piezoelectric device array shows an exceptional piezoelectric sensitivity with a high-level uniformity and excellent environmental stability under ambient conditions. A detailed study of the sulfur vacancy-dependent property and its resultant asymmetric structure-induced piezoelectricity is reported. The proposed approach is scalable and can produce advanced materials for flexible piezoelectric devices to be used in emerging bioinspired robotics and biomedical applications.
Date:
May 2021
Creator:
Kim, Junyoung
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Defining Learning Affordances Based on Past Research Uses
The objective of this study was to locate and describe the learning affordances used within research studies on instructional design. Allowing an instructional designer to see what was used and how applicable it might be for future design would assist with better course creation. Current and past literature supported the importance of this concept after examination of how course creation has evolved within the field of instructional design. Further, the findings elucidated how to help the field evolve in the future by expanding knowledge about learning affordances and providing the broadest set of conceptual definitions by the academics working in the field to include them in their research and instructional designs.
Date:
December 2021
Creator:
Dolliver, Elizabeth Anne
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Design, Fabrication and Testing of a Novel Dual-Axis Automatic Solar Tracker System Using a Fresnel-Lens Solar Concentrator
This thesis project investigates, analyzes, designs, simulates, constructs and tests a dual-axis solar tracker system to track the sun and concentrates the heat of the sunlight, using a Fresnel lens, into a small area, which is above of an evaporator, to increase the temperature of the seawater to convert it into freshwater. The dual-axis solar tracker was designed with the main objectives that the structure was portable, dismountable, lightweight, low cost, corrosion resistant, wires inside pipes, accurate, small size, follow the sun automatically, off-grid (electrical), use green energy (solar powered), and has an empty area right below of the lens. First, a 500 mm diameter flat Fresnel lens was selected and simulated based on an algorithmic method achieved by a previous PhD student at UNT using MATLAB®, to give the optimization lens dimensions. The lens profile was drawn with AutoCAD®, then output profile lens was simulated in COMSOL Multiphysics®. The objective was to provide the high efficiency, optimum and high precision of the focal rays and heat to the receiver of the evaporator. A novel dual-axis solar tracker system was then designed that is portable, dismountable, lightweight and corrosion resistant. The solar tracker tracks the sun in two axis of …
Date:
August 2021
Creator:
Almara, Laura Mabel
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Design of Low-Power Front End Compressive Sensing Circuitry and Energy Harvesting Transducer Modeling for Self-Powered Motion Sensor
Compressed sensing (CS) is an innovative approach of signal processing that facilitates sub-Nyquist processing of bio-signals, such as a neural signal, electrocardiogram (ECG), and electroencephalogram (EEG). This strategy can be used to lower the data rate to realize ultra-low-power performance, As the count of recording channels increases, data volume is increased resulting in impermissible transmitting power. This thesis work presents the implementation of a CMOS-based front-end design with the CS in the standard 180 nm CMOS process. A novel pseudo-random sequence generator is proposed, which consists of two different types of D flip-flops that are used for obtaining a completely random sequence. This thesis work also includes the (reverse electrowetting-on-dielectric) REWOD based energy harvesting model for self-powered bio-sensor which utilizes the electrical energy generated through the process of conversion of mechanical energy to electrical energy. This REWOD based energy harvesting model can be a good alternative to battery usage, particularly for the bio-wearable applications. The comparative analysis of the results generated for voltage, current and capacitance of the rough surface model is compared to that of results of planar surface REWOD.
Date:
August 2021
Creator:
Kakaraparty, Karthikeya Anil Kumar
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library