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open access

The Sound Systems of Zophei Dialects and Other Maraic Languages

Description: This dissertation presents in-depth description and analysis the Zophei sound system within the context of the closely-related Maraic languages. Zophei (or Zyphe, ISO 639-3 ZYP), a previously undocumented member of the Maraic branch of Kuki-Chin (or South-Central Tibeto-Burman) spoken in Southern Thantlang Township, Chin State, Burma/Myanmar and by thousands of speakers in Indianapolis, Indiana. Using primary data elicited during three years of fieldwork, the sound systems of Lawngtlang, Tlawngrang, and Nuitah Zophei are investigated in detail. Special attention is paid to the segmental, syllable structure, and tonal inventories. A long history of language contact in the Maraic-speaking world has brought on radical innovations in syllable structure, vowel systems, and tone that have, as of yet, seen little linguistic analysis. Outside of the present research program, no previous linguistic work on Zophei exists. As such, this thesis endeavors to describe and analyze the sound systems of Zophei varieties.
Date: December 2021
Creator: Lotven, Samson
Partner: UNT College of Information

A Proposal for a Training Program to Support Culturally Responsive Professional-Family Interactions

Description: Behavior analysts often work with families from diverse cultural backgrounds. Ideally, behavior analysts and families interact in ways that are responsive to the family's culture and valued outcomes. The data indicate that most behavior analysts, however, come from one dominant cultural group. This is a proposal for training program and evaluation method to support culturally responsive professional-family interactions. This proposed study is designed to be conducted via Zoom-- a cloud-based video conferencing service. A pre-post treatment design is proposed to assess the effects of the training. Hypothetical data were generated to consider the range of effects such a program might have on trainee responses to written/live scenarios. Responses in the observation protocol included written descriptions, empathetic statements, perspective taking statements, and non-verbal behaviors. Overall, the program was designed using evidence-based procedures and is likely to support behavior analysts in training and in practice to improve their interactions with families and become more culturally responsive to groups of people that are from the non-dominant culture.
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Date: December 2021
Creator: Anegbeh, Cynthia Momoh
Partner: UNT Libraries

Spatial-Temporal Assessment of Irrigation Application Changes and Soil Moisture Analysis Using SMAP Maps

Description: Due to inadequate long-term and large-scale observation approach for observation of soil moisture across the globe, this study intends to unveil the importance of using simulated soil moisture fields from land surface models, forced with observed precipitation and near-surface meteorology in monitoring drought and formulating effective water management practices for continued production irrigation applications. This study shows that socio-economic and ecosystem effects can be determined by evaluating spatial-temporal changes in irrigation applications. Thus, it facilitates understanding of the importance of water management and how water, energy, and carbon flows protect our climate and environment. By using Soil Moisture Active Passive (SMAP) in monitoring soil moisture, the information obtained is critical in providing early drought warnings, particularly in those parts of the United States that experience flash agricultural droughts. Further, this study highlights that frequent and reliable soil moisture measurements from SMAP helped improve the predictive capability of weather and climate models.
This item is restricted from view until January 1, 2024.
Date: December 2021
Creator: Unal, Kerra
Partner: UNT Libraries
open access

A Preliminary Analysis of the Effects of a Training Program to Teach Skilled Dialogue to a Behavior Analyst Working in a Culturally Diverse Setting

Description: Diversity can serve as both a unifying force as well as grounds for intolerance of differences. Behavior analysts working in applied settings often encounter diversity and it is in these settings that meaningful relationships and harmonious collaboration are vital. Skilled dialogue has been recommended as an approach to capitalizing on diverse perspectives so that new solutions and meaningful relationships are developed. The purpose of the present study was to evaluate the effects of a training workshop to teach skilled dialogue to behavior analysts. The participant was trained to provide welcoming, allowing, sense-making, appreciating, joining, and harmonizing statements using instructions, rationales, models, role-plays, and feedback. The effects of the training workshop were evaluated using a multiple baseline design across training components. Audio responses to role-play scenarios were recorded, transcribed, and scored in order to assess the effects of the training workshop on communication skills. The results of the study indicated that this training workshop is an effective method to teach behavior analysts to engage in the components of skilled dialogue, hopefully contributing to harmonious collaborative communication in their work settings.
Date: December 2021
Creator: Reese, Ashlee Keisha-Nikol
Partner: UNT Libraries

Analysis of the Integration of LEO Satellite Constellations into 5G Networks

Description: Low Earth orbit (LEO) satellite systems have been proposed as a resource for combating the challenges in 5G network coverage and expanding connectivity to a global realm. This research focuses on the current architecture of LEO satellite constellations, with an emphasis on satellite coverage, visibility patterns and coordination schemes. Key-elements of integrating LEO satellites into the eMBB component of 5G are presented and a breakdown of potential link channel characteristics and physical layer performance metrics are described. The produced information allows for a justified analysis on the conceptualized integration.
This item is restricted from view until July 1, 2022.
Date: December 2021
Creator: Cruz Vazquez, Martin
Partner: UNT Libraries
open access

A Behavior Analytic Account of Humor Responses: Taking a Joke Way Too Seriously

Description: Compared to other examples of human behavior, humor responses have received relatively little attention from the scientific community and by the behavior analytic community in particular. This study investigated what some of the controlling variables for humans to emit a humor response may be. Participants were randomly presented two types of word sequences/jokes: one with a matching punchline and one without a matching punchline. Participants rated whether the jokes were funny or not funny, and reaction time was measured for all stimuli presented. Generally, the results showed that reaction times to punchlines rated as not funny were shorter than punchlines that were rated funny. These differences in reaction time were interpreted with priming, intraverbal control, and multiple control as an experimental foundation. Limitations include the absence of physiological measures due to COVID-19 restrictions and the forced choice of two rating responses. The implications of this research reveal opportunities for future research of humor responses.
Date: December 2021
Creator: Amezquita IV, Edward Brandon
Partner: UNT Libraries
open access

Counting Plane Tropical Curves via Lattice Paths in Polygons

Description: 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
Partner: UNT Libraries
open access

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

Description: 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
Partner: UNT Libraries
open access

Domain Specific Cognitive Effects of Sickle Cell Disease in Children

Description: Multiple contributors to neurocognitive impairment in individuals with sickle cell disease have been identified. Research indicates that a history of cerebrovascular accidents, such as silent infarcts and strokes are associated with greater cognitive decline among children with sickle cell disease. Additionally, disease effects such as hemoglobin and hematocrit levels significantly effect cognitive performance among this population and should be taken into consideration when examining neurocognitive impairment. Further, previous studies show a significant relationship between child behavior problems, family functioning, and cognitive performance in children with sickle cell, marking those as important targets for intervention among this population. While cognitive decline with increased age is not typically examined in healthy child populations, some research indicates the presence of age effects in those with SCD. A majority of the literature addresses cognitive impairment from a broad perspective, while a limited number of studies have begun to address effects among specific cognitive domains. Using archival data from the National Institutes of Health's Cooperative Study of Sickle Cell Disease, results revealed that disease severity was negatively correlated with some aspects of cognitive functioning, including visual-spatial domains. Additionally, some measures of cognitive performance were inversely correlated with age. Consistent with hypothesized outcomes, family functioning was strongly associated with measures of cognitive functioning. Implications are discussed.
Date: December 2021
Creator: Carroll, Bridgette
Partner: UNT Libraries
open access

The Examination of Black and Latino/a/x Students' and Responsive STEM Teachers' Perceptions of Teacher Cultural Consciousness and Culturally Responsive Instructional Practices

Description: School cultures, curriculum, and instruction are too often created through a monocultural lens, which excludes Black and Latino/a/x students both socially and academically, and perpetuates the false notion that these students are inherently less capable of achieving academic success when compared to their White counterparts. This is visible across all content areas, but especially in secondary science, technology, engineering, and mathematics (STEM) classes, which means that our Black and Latino/a/x students are continually denied preparation for the critical, high demand careers in the STEM field. Just as critical, with the dominance of White teachers in the classroom, out Black and Latino/a/x students often do not have access to teachers who share their lived experiences or who understand the nuances of their home cultures. However, teachers and school instructional leaders can change course by focusing their efforts to develop a rich cultural consciousness, and by focusing on the utilization of culturally responsive pedagogy (CRP) and related instructional strategies with great intentionality in the classroom. This mixed method, single site, exploratory case study was conducted to examine Black and Latino/a/x students' perceptions of their culturally responsive STEM teachers' cultural consciousness, and culturally responsive STEM teachers' perceptions of culturally responsive practices and their Black and Latino/a/x academic abilities. The results provide a clear discrepancy between STEM teacher and Black and Latino/a/x student perspectives that emphasizes a tension between them. This tension must be further explored and highlights a critical need for STEM specific professional development that encompasses both culturally responsive practices and opportunities to develop a critical consciousness.
Date: December 2021
Creator: Norris, Margaret Louise
Partner: UNT Libraries
open access

Unraveling the Effect of Atomic Configurations and Structural Statistics on Mechanical Behavior of Multicomponent and Amorphous Alloys

Description: Multicomponent high-entropy and amorphous alloys represent relatively new classes of structural materials with complex atomic configurations and exceptional mechanical properties. However, there are several knowledge gaps in the relationships between their atomic structure and mechanical properties. Understanding these critical relationships will enable novel alloy design and tailoring of their mechanical properties for desired engineering applications. In this dissertation, first-principles calculations and molecular dynamics simulations are applied to investigate the local atomic configurations and ordering in high-entropy and amorphous alloys. Our findings suggest that fluctuations in local atomic configurations for high- entropy alloys result in significant changes in stacking fault energy, twin energy, dislocation behavior, dislocation-twin interactions, and critical shear stress. For amorphous alloys or metallic glasses, the short-range order (SRO) and medium-range order (MRO) were found to play decisive roles in determination of their mechanical properties. Structural relaxation was found to lead to shear localization, which was attributed to free volume change and evolution of SRO and MRO to more brittle nature. In contrast, rejuvenated metallic glasses had relatively large and uniform free volume distribution giving rise to homogeneous flow and increased plasticity.
Date: December 2021
Creator: Yang, Yu Chia
Partner: UNT Libraries
open access

English Learner Instructional Programs in Texas Charter Schools: Perspectives of Instructional Leaders in Their Selection of Bilingual/ESL Programs

Description: There are 184 active charter school districts in Texas, which use public tax dollars like traditional school districts, providing educational opportunities to over 350,000 Texas students. Charter schools accept state and federal funds and often operate with less oversight than their neighboring local public schools, yet they have the autonomy to accomplish the mission(s) set forth by the charter school operator. Although there have been numerous studies looking at the effectiveness of charter schools in terms of student achievement, very little research has been on the programs that charter schools implement to address the needs of their English learner populations. This study examined charter school leaders' perceptions in the selection of the EL instructional programs that are offered to their English Learners. Interviews of district bilingual/ESL directors of Texas charter schools, or their equivalents, were conducted. Using a constructivist grounded theory design, this study explored the factors and decisions of instructional leaders in implementing a particular second language program, with special attention to the ideologies informing these decisions. Themes emerged from the data and were be explored. The findings of this study are vital in helping other charter school operators better understand the challenges and potential pitfalls faced by current charter school operators in supporting their EL populations.
Date: December 2021
Creator: Navarrete, Jesús Leopoldo
Partner: UNT Libraries
open access

The Convolutional Recurrent Structure in Computer Vision Applications

Description: 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 convolutional fully-connected neural networks with hard sample memory pool structure (CFMP) is invented to tackle the remote sensing land use image classification tasks. The CRLUC and CFMP algorithm performances are tested in popular datasets. Experimental studies show the proposed algorithms can classify images with higher accuracy and fewer training episodes compared to popular image classification algorithms.
Date: December 2021
Creator: Xie, Dong
Partner: UNT Libraries

Materials Approaches for Transparent Electronics

Description: This dissertation tested the hypothesis that energy transferred from a plasma or plume can be used to optimize the structure, chemistry, topography, optical and electrical properties of pulsed laser deposited and sputtered thin-films of ZnO, a-BOxNy, and few layer 2H-WS2 for transparent electronics devices fabricated without substrate heating or with low substrate heating. Thus, the approach would be compatible with low-temperature, flexible/bendable substrates. Proof of this concept was demonstrated by first optimizing the processing-structure-properties correlations then showing switching from accumulation to inversion in ITO/a-BOxNy/ZnO and ITO/a-BOxNy/2H-WS2 transparent MIS capacitors fabricated using the stated processes. The growth processes involved the optimization of the individual materials followed by growing the multilayer stacks to form MIS structures. ZnO was selected because of its wide bandgap that is transparent over the visible range, WS2 was selected because in few-layer form it is transparent, and a-BOxNy was used as the gate insulator because of its reported atomic smoothness and low dangling bond concentration. The measured semiconductor-insulator interfacial trap properties fall in the range reported in the literature for SiO2/Si MOS structures. X-ray photoelectron spectroscopy (XPS), Hall, photoluminescence, UV-Vis absorption, and X-ray diffraction (XRD) measurements investigated the low-temperature synthesis of ZnO. All films are nanocrystalline with the (002) XRD planes becoming more prominent in films grown with lower RF power or higher pressure. Low power or high chamber pressure during RF magnetron sputtering resulted in a slower growth rate and lower energetic conditions at the substrate. Stoichiometry improved with RF power. The measurements show a decrease in carrier concentration from 6.9×1019 cm-3 to 1.4×1019 cm-3 as power increased from 40 W to 120 W, and an increase in carrier concentration from 2.6×1019 cm-3 to 8.6×1019 cm-3 as the deposition pressure increased from 3 to 9 mTorr. The data indicates that in the range of conditions used, …
This item is restricted from view until January 1, 2023.
Date: December 2021
Creator: Iheomamere, Chukwudi Emmanuel
Partner: UNT Libraries
open access

Examining the Barriers and Benefits of a PhD Nursing Program Using a Systems Construct Approach: A Case Study

Description: The purpose of this exploratory qualitative case study is to describe the formation of a graduate enrollment evaluation system (GEES) to capture and explore the perceptions of key stakeholders to critically examine the barriers and benefits of a PhD nursing program at a large, public designated high research institution. As the research suggest, there is a current need for increased enrollment for nurses into nursing doctorate programs to further meet the patient's expanding demand, to expand the science of the nursing profession, and to increase the pipeline of qualified nursing faculty. Without a pipeline of qualified nursing faculty, fewer new nurses can be trained for the nursing workforce that already experiences a critical deficiency in staffing.
Date: December 2021
Creator: Johnson, Charles
Partner: UNT Libraries
open access

The Study of Network Governance in Continuum of Care (CoC), Homeless Service Networks in the US: Institutional Collective Action Framework

Description: The dissertation investigates the form of network governance in the context of U.S. homeless service networks (namely continuum of care programs; CoCs). This research examines CoC homeless service networks by applying the institutional collective action (ICA) perspectives to understand the forms of network governance as a reflection of network context. The ICA perspective has been applied to understand the rational behavior of network members for the network governance form to mitigate the collective action problems. The ICA perspective helps understand why network members accept specific governance structures with their expectation to maximize the benefits and minimize the costs and uncertainty in their process of collaboration. This dissertation uses the data of CoC networks and point in time data from the U.S. Department of Housing and Urban Development in 2019 and Census. The data developed for this study offers the homeless incidences, geographical characteristics, and governance structure based on the contact information. For an in-depth understanding, interview by CoC leaders was integrated. This dissertation consists of four essays about 1) Literature review on network governance and the theoretical argument in the ICA framework, 2) Background and network governance of the U.S. homeless service networks, 3) Factors affecting the choice of network administrative organization (NAO) form, and 4) Interviews by the representatives of CoC networks. The findings inform us of the governance structure for the effective service provisions and coordination of actions of network members and about why and how network organizations choose a form of network governance.
Date: December 2021
Creator: Jeong, Jihoon
Partner: UNT Libraries
open access

Reform on Educational Policy: The Alignment of Career and Technical Education Programs of Study to Local Labor Markets

Description: Do federal policies influence program offerings for career and technical education(CTE)? Often the implication of compliance and the expectation of connecting compliance to funding is considered a tactic to leverage expectations on a large scale. The purpose of this quantitative study was to determine if the CTE programs located in a singular region of Texas were compliant with federal expectations by way of evaluating the alignment of programs offered and local labor markets prior to the implementation of Perkins V. The evaluation of a variety of archival data and subsequent findings of the correlation of alignment of programs within the region along with the amount of federal Perkins's dollars spent on CTE was a confirmed as an effective policy reform measure. Additional evaluations included the combination of federal and state spending in correlation to the number of programs offered in career and technical education along with the actual CTE student enrollment of a given district. Major findings showed that through a moderation analysis for some districts the number of programs offered could be influenced by program funding and size. In addition, this study confirmed that many programs are indeed compliant, however compliance does not guarantee program opportunities when resources and enrollment are abundant. Recommendations for future studies concerning administrative decisions for programming and compliance are discussed.
Date: December 2021
Creator: Braswell, CyLynn
Partner: UNT Libraries

First Principles Study of the Effect of Local Bonding on Diffusion Mechanisms in Alloys

Description: This work demonstrates how local, randomized tailoring of bond stiffness can affect the activation energy of diffusion in model alloys using density functional theory-based computations. This work is organized into two parts. The first part deals with the vacancy diffusion mechanism, and it compares the in–plane (IP) vs out-of-plane (OOP) diffusion paths in prototypical binary Mg-X (Ca, Y, and Gd) and ternary Mg-X (Ca, Y, and Gd)-Zn alloys. We examine how vacancy formation, migration, and solute vacancy binding energies in binary Mg-X alloys influence diffusion activation and correlated them with conventional diffusion model based solely on the solute sizes. Next, we explore how Zn addition to binary Mg-X (Ca, Y, and Gd) alloys influences the OOP activation energy barrier is discussed in terms of detailed energetic computations and bond characterization in the present work. Our results indicate that Zn addition further enhances the OOP activation energy barrier compared to corresponding activation energies in Mg binaries. This work concludes that engineering stiffer directional bonds via micro-alloying additions in Mg is a promising route to dramatically improve their high temperature creep response. The second part of my work investigates the effects of Si, P, and S solutes on H interstitial diffusion mechanism in Ni. It examines how H interacts with vacancy, impurity atom, and vacancy-impurity atom defect pair by performing binding energy calculations. Results indicate that vacancy-impurity atom defect pair strongly traps the H atom compared to isolated defects. Finally, the effect of impurities on activation energy barrier of H diffusing in Ni is discussed by correlating migration energetics with bonding characteristics by performing charge density and electron density calculations. Our study validates experimental hypothesis of Berkowitz and Kane which postulates that P enhances the H diffusion in Ni. The present work also shows that H diffusion speeds up in Ni in …
This item is restricted from view until July 1, 2022.
Date: December 2021
Creator: Paranjape, Priyanvada Madhukar
Partner: UNT Libraries
open access

Teaching through the COVID-19 Pandemic: The Experiences and Perspectives of United States Lower Elementary Teachers

Description: The purpose of this qualitative multiple case study is to identify and describe the perceptions and experiences of lower elementary public-school teachers in the United States teaching with educational technologies during the COVID-19 pandemic. Through a demographic survey and semi-structured interviews, teachers shared their experiences regarding the barriers they encountered teaching and learning with educational technologies in face-to-face, remote, and hybrid classrooms. The multi-phase coding process used emic and etic codes to analyze the data. This study identifies and describes the existing barriers teachers face with learning technologies in the classroom before COVID-19 and the new obstacles they have encountered due to the pandemic. The results of this study are discussed, and recommendations are provided to help researchers identify the essential supports educators need for future emergencies.
Date: December 2021
Creator: Kinard, Widad S.
Partner: UNT Libraries
open access

Living Art, Living History, Living Material: Exploring the Impact of Heritage Clothing and Materials on Museum Educator Pedagogy

Description: Historical dress as a museum theater and research process encompasses material, technological, and cultural experiences from the past in the present. This research examines how intimate experiences with heritage materials, processes, and environments may impact development of educator pedagogy. Historical attractions in the US draw visitors due in part to providing guests with context for the objects and built environments displayed. New Materialist theory offers insights into how inanimate objects and environments "teach" human and non-human entities in their own right. Using a New Materialist lens, I observed, interviewed, and conducted participant observations through a novel research methodology, intra-active narrative inquiry, with costumed museum educators to better discern how relations between humans and historical materials intra-act as embodied experiences of object knowledge in museum pedagogy.
Date: December 2021
Creator: Harper, Sarah Ellen
Partner: UNT Libraries
open access

Additive Manufacturing of AZ31B Magnesium Alloy via Friction Stir Deposition

Description: 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, X-ray diffraction, scanning electron microscopy, electron back scatter diffraction (EBSC), contact angle measurement and micro hardness tests. The AFSD AZ31B samples showed reduction in areal surface roughness with an increase in the tool linear velocity. The X-ray spectra revealed increase in the intensity of prismatic planes of α-Mg phase with increase in tool linear velocity. AFSD of AZ31B Mg alloy resulted in shifting of the grain size from a broader and courser distribution within the feed material to a tighter distribution. Moreover, EBSD observations confirmed the refinement in grain size distribution as well as the presence of predominantly prismatic texture …
Date: December 2021
Creator: Patil, Shreyash Manojkumar
Partner: UNT Libraries

"Nature Study"

Description: A collection of poetry concerned with loss and the act of creation.
This item is restricted from view until January 1, 2024.
Date: December 2021
Creator: Abercrombie, Ben
Partner: UNT Libraries

Reliability Characterization and Performance Analysis of Solid State Drives in Data Centers

Description: NAND flash-based solid state drives (SSDs) have been widely adopted in data centers and high performance computing (HPC) systems due to their better performance compared with hard disk drives. However, little is known about the reliability characteristics of SSDs in production systems. Existing works that study the statistical distributions of SSD failures in the field lack insights into distinct characteristics of SSDs. In this dissertation, I explore the SSD-specific SMART (Self-Monitoring, Analysis, and Reporting Technology) attributes and conduct in-depth analysis of SSD reliability in a production environment with a focus on the unique error types and health dynamics. QLC SSD delivers better performance in a cost-effective way. I study QLC SSDs in terms of their architecture and performance. In addition, I apply thermal stress tests to QLC SSDs and quantify their performance degradation processes. Various types of big data and machine learning workloads have been executed on SSDs under varying temperatures. The SSD throughput and application performance are analyzed and characterized.
This item is restricted from view until January 1, 2023.
Date: December 2021
Creator: Liang, Shuwen
Partner: UNT Libraries
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