A 3% Measurement of the Beam Normal Single Spin Asymmetry in Forward Angle Elastic Electron-Proton Scattering using the Qweak Setup (open access)

A 3% Measurement of the Beam Normal Single Spin Asymmetry in Forward Angle Elastic Electron-Proton Scattering using the Qweak Setup

The beam normal single spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable of the imaginary part of the two-photon exchange process. Moreover, it is a potential source of false asymmetry in parity violating electron scattering experiments. The Q{sub weak} experiment uses parity violating electron scattering to make a direct measurement of the weak charge of the proton. The targeted 4% measurement of the weak charge of the proton probes for parity violating new physics beyond the Standard Model. The beam normal single spin asymmetry at Q{sub weak} kinematics is at least three orders of magnitude larger than 5 ppb precision of the parity violating asymmetry. To better understand this parity conserving background, the Q{sub weak} Collaboration has performed elastic scattering measurements with fully transversely polarized electron beam on the proton and aluminum. This dissertation presents the analysis of the 3% measurement (1.3% statistical and 2.6% systematic) of beam normal single spin asymmetry in electronproton scattering at a Q2 of 0.025 (GeV/c)2. It is the most precise existing measurement of beam normal single spin asymmetry available at the time. A measurement of this precision helps to improve the theoretical models on beam normal …
Date: August 1, 2013
Creator: Waidyawansa, Dinayadura Buddhini
System: The UNT Digital Library
9-Lipoxygenase Oxylipin Pathway in Plant Response to Biotic Stress (open access)

9-Lipoxygenase Oxylipin Pathway in Plant Response to Biotic Stress

The activity of plant 9-lipoxygenases (LOXs) influences the outcome of Arabidopsis thaliana interaction with pathogen and insects. Evidence provided here indicates that in Arabidopsis, 9-LOXs facilitate infestation by Myzus persicae, commonly known as the green peach aphid (GPA), a sap-sucking insect, and infection by the fungal pathogen Fusarium graminearum. in comparison to the wild-type plant, lox5 mutants, which are deficient in a 9-lipoxygenase, GPA population was smaller and the insect spent less time feeding from sieve elements and xylem, thus resulting in reduced water content and fecundity of GPA. LOX5 expression is induced rapidly in roots of GPA-infested plants. This increase in LOX5 expression is paralleled by an increase in LOX5-synthesized oxylipins in the root and petiole exudates of GPA-infested plants. Micrografting experiments demonstrated that GPA population size was smaller on plants in which the roots were of the lox5 mutant genotype. Exogenous treatment of lox5 mutant roots with 9-hydroxyoctadecanoic acid restored water content and population size of GPA on lox5 mutants. Together, these results suggest that LOX5 genotype in roots is critical for facilitating insect infestation of Arabidopsis. in Arabidopsis, 9-LOX function is also required for facilitating infection by F. graminearum, which is a leading cause of Fusarium head …
Date: May 2012
Creator: Nalam, Vamsi J.
System: The UNT Digital Library
The 50,000 Watt Blowtorch of the Great Southwest: The History of WBAP (open access)

The 50,000 Watt Blowtorch of the Great Southwest: The History of WBAP

This paper looks at the history of WBAP while examining how programming has changed from 1922-2014 and how WBAPs audience helped shape programming at the station. This paper reveals four formatting changes throughout the stations history and provides in-depth statistical analysis of how WBAPs audience changed during the stations 90 plus years of existence.
Date: December 2016
Creator: Dixon, Chad M
System: The UNT Digital Library
161 Glass: Site Specific Music in an Artistic Context (open access)

161 Glass: Site Specific Music in an Artistic Context

The composition 161 Glass is a 17-minute musical work with percussion, wind and brass instruments in which the intersection of mid-century architecture, and the art and culture of a dynamic city are inextricably linked. Through this paper, I explore the process of composing a musical work in relationship to the significance of site specific context. The paper begins by defining the concept of site specific art works; then reviews the discourse of the intersection of art, music and architecture. I then delve into the cultural and geographic context surrounding this project from the modern era through the present, and how those perspectives apply to the building and my piece. I reveal how the composition relates the musical ideas to the site. Finally, I describe the collaborative process between myself, the musicians and the Dallas Contemporary staff.
Date: May 2010
Creator: Rusnak, Christina S.
System: The UNT Digital Library
A 018μm Cmos Transmitter for Ecg Signals (open access)

A 018μm Cmos Transmitter for Ecg Signals

Electrocardiography (ECG) signal transmitter is the device used to transmit the electrical signals of the heart to the remote machine. These electrical signals are ECG signals caused due to electrical activities in the heart. ECG signals have very low amplitude and frequency; hence amplification of the signals is needed to strengthen the signal. Conversion of the amplified signal into digital information and transmitting that information without losing any data is the key. This information is further used in monitoring the heart.
Date: December 2013
Creator: Kakarna, Tejaswi
System: The UNT Digital Library

489 Days

Access: Use of this item is restricted to the UNT Community
489 Days is an animated documentary about the harrowing experiences of Egyptian-American Mohamed Soltan, who survived 16 months of hunger strike in an Egyptian prison. Caught up in the political turmoil which followed the Arab Spring uprisings, Soltan was unjustly incarcerated between August 2013 and May 2015, when the United States government intervened to release him weeks after an Egyptian court sentenced him to life in prison. The film is also the larger story of an estimated 60,000 political detainees currently held in Egypt without due process, and in violation of local and international human rights conventions.
Date: August 2019
Creator: Elmalky, Rania
System: The UNT Digital Library
The 1896 Vienna Tonkünstler-verein Competition: the Three Award-winning Works and Seven Anonymous Submissions with Clarinet (open access)

The 1896 Vienna Tonkünstler-verein Competition: the Three Award-winning Works and Seven Anonymous Submissions with Clarinet

The Vienna Tonkünstler-Verein (1885-1929) was established for the sole purpose of providing extensive support to the music and musicians of Vienna. The society became renowned in Vienna for its outstanding performances of chamber music and counted among its members many of the city’s foremost musicians and composers. Johannes Brahms had a significant influence on the society as its honorary president and assisted in establishing its composition competitions, aimed at promoting and reviving under-developed chamber genres. Of particular interest to clarinetists is the Verein’s competition of 1896, which aspired to promote chamber music literature for wind instruments. Brahms’s recently completed chamber works for clarinet were clearly influential in fin-de-siècle Vienna; for of the twelve works chosen as finalists in the competition, ten included the clarinet in the chamber combination.The purpose of this document is to provide an English-language history of the Vienna Tonkünstler-Verein and a thorough account of its1896 competition based on my study of the society’s annual reports. In addition, this document will provide the first published account of the anonymous submissions for the 1896 competition. It is my hope that this paper will serve as a springboard for future endeavors aimed at uncovering the identities of the anonymous finalists …
Date: August 2014
Creator: Harrell, Andrea
System: The UNT Digital Library
2D and 3D Fabrication Devices: Can They Improve Spatial Reasoning Skills in Children? (open access)

2D and 3D Fabrication Devices: Can They Improve Spatial Reasoning Skills in Children?

The purpose of this study is to evaluate the potential benefit of two hours of activities involving 2D and 3D fabricators on the spatial reasoning skills of children in Grades 4 and 5, ages 9 to 10, from a private school in Southeast Texas. Can the introduction to hands-on activities with products created with these devices and learning about how these devices operate improve spatial reasoning skills? The research also evaluates the use of the Shapes Test as a valid measure of the spatial reasoning skills of children. The Cube Design and Spatial Memory subtests of the UNIT (Universal Nonverbal Intelligence Tests) were used for evaluating the spatial reasoning skills of the participants, based on their respected validity, along with a Shapes Test that is in development. Discussion regarding gender, language, and experiential theories of spatial reasoning skill development are included in the literature review.
Date: August 2016
Creator: Zimmerman, Ellen L
System: The UNT Digital Library
3D Reconstruction Using Lidar and Visual Images (open access)

3D Reconstruction Using Lidar and Visual Images

In this research, multi-perspective image registration using LiDAR and visual images was considered. 2D-3D image registration is a difficult task because it requires the extraction of different semantic features from each modality. This problem is solved in three parts. The first step involves detection and extraction of common features from each of the data sets. The second step consists of associating the common features between two different modalities. Traditional methods use lines or orthogonal corners as common features. The third step consists of building the projection matrix. Many existing methods use global positing system (GPS) or inertial navigation system (INS) for an initial estimate of the camera pose. However, the approach discussed herein does not use GPS, INS, or any such devices for initial estimate; hence the model can be used in places like the lunar surface or Mars where GPS or INS are not available. A variation of the method is also described, which does not require strong features from both images but rather uses intensity gradients in the image. This can be useful when one image does not have strong features (such as lines) or there are too many extraneous features.
Date: December 2012
Creator: Duraisamy, Prakash
System: The UNT Digital Library
3GPP Long Term Evolution LTE Scheduling (open access)

3GPP Long Term Evolution LTE Scheduling

Future generation cellular networks are expected to deliver an omnipresent broadband access network for an endlessly increasing number of subscribers. Long term Evolution (LTE) represents a significant milestone towards wireless networks known as 4G cellular networks. A key feature of LTE is the implementation of enhanced Radio Resource Management (RRM) mechanism to improve the system performance. The structure of LTE networks was simplified by diminishing the number of the nodes of the core network. Also, the design of the radio protocol architecture is quite unique. In order to achieve high data rate in LTE, 3rd Generation Partnership Project (3GPP) has selected Orthogonal Frequency Division Multiplexing (OFDM) as an appropriate scheme in terms of downlinks. However, the proper scheme for an uplink is the Single-Carrier Frequency Domain Multiple Access due to the peak-to-average-power-ratio (PAPR) constraint. LTE packet scheduling plays a primary role as part of RRM to improve the system’s data rate as well as supporting various QoS requirements of mobile services. The major function of the LTE packet scheduler is to assign Physical Resource Blocks (PRBs) to mobile User Equipment (UE). In our work, we formed a proposed packet scheduler algorithm. The proposed scheduler algorithm acts based on the number …
Date: December 2013
Creator: Alotaibi, Sultan
System: The UNT Digital Library
Ab Initio and Density Functional Investigation of the Conformer Manifold of Melatonin and a Proposal for a Simple Dft-based Diagnostic for Nondynamical Correlation (open access)

Ab Initio and Density Functional Investigation of the Conformer Manifold of Melatonin and a Proposal for a Simple Dft-based Diagnostic for Nondynamical Correlation

In this work we address two problems in computational chemistry relevant to biomolecular modeling. In the first project, we consider the conformer space of melatonin as a a representative example of “real-life” flexible biomolecules. Geometries for all 52 unique conformers are optimized using spin-component scaled MP2, and then relative energies are obtained at the CCSD (T) level near the complete basis set limit. These are then used to validate a variety of DFT methods with and without empirical dispersion corrections, as well as some lower-level ab initio methods. Basis set convergence is found to be relatively slow due to internal C-H…O and C-H…N contacts. Absent dispersion corrections, many DFT functionals will transpose the two lowest conformers. Dispersion corrections resolve the problem for most functionals. Double hybrids yield particularly good performance, as does MP2.5. In the second project, we propose a simple DFT-based diagnostic for nondynamical correlation effects. Aλ= (1-TAE [ΧλC]/TAE[XC])/λ where TAE is the total atomization energy, XC the “pure” DFT exchange-correlation functional, and ΧλC the corresponding hybrid with 100λ% HF-type exchange. The diagnostic is a good predictor for sensitivity of energetics to the level of theory, unlike most of the wavefunction-based diagnostics. For GGA functionals, Aλ values approaching unity …
Date: August 2013
Creator: Fogueri, Uma
System: The UNT Digital Library
Abelian Group Actions and Hypersmooth Equivalence Relations (open access)

Abelian Group Actions and Hypersmooth Equivalence Relations

We show that any Borel action on a standard Borel space of a group which is topologically isomorphic to the sum of a countable abelian group with a countable sum of lines and circles induces an orbit equivalence relation which is hypersmooth. We also show that any Borel action of a second countable locally compact abelian group on a standard Borel space induces an orbit equivalence relation which is essentially hyperfinite, generalizing a result of Gao and Jackson for the countable abelian groups.
Date: May 2019
Creator: Cotton, Michael R.
System: The UNT Digital Library
Ability of Offenders with Psychopathic Traits to Simulate Cognitive and Affective Empathy (open access)

Ability of Offenders with Psychopathic Traits to Simulate Cognitive and Affective Empathy

The accurate assessment of psychopathy constitutes a critical component of forensic assessments addressing offender populations. Among the core characteristics of psychopathy, the interpersonal component of deception and empathic deficits are prominently observed in offenders with psychopathic traits. Given the negative consequences of being classified as a psychopath, offenders may be likely to minimize their psychopathic traits. In particular, no research has investigated whether offenders with psychopathic traits are able to simulate empathy in an effort to mask their cognitive or affective empathy deficits (e.g., lack of remorse about offenses). The present study aims to contribute to the literature with regard to the simulation of empathy. Using a mixed between- and within-subjects design, 81 male detainees were placed into (a) a low psychopathy group, (b) a moderate psychopathy group, or (c) a high psychopathy group based on the Psychopathy Checklist – Revised. For the within-subjects component, all offenders answered empathy questionnaires under genuine and simulation conditions. Results indicate the sample possessed cognitive empathy, but did not display affective empathy under genuine instructions. Under simulation instructions, participants significantly increased their scores on several empathy measures. The implications of simulated empathy and comparisons between groups regarding simulation abilities are discussed.
Date: August 2013
Creator: Robinson, Emily V.
System: The UNT Digital Library
Absorptive Capacity:  An Empirical Examination of the Phenomenon and Relationships with Firm Capabilities (open access)

Absorptive Capacity: An Empirical Examination of the Phenomenon and Relationships with Firm Capabilities

The field of strategic management addresses challenges that firms encounter in an attempt to remain competitive. The ability to explain variation in firm success through examination of knowledge flows has become a prominent focus of research in the strategic management literature. Specifically, researchers have sought to further examine how firms convert knowledge, a phenomenon conceptualized as absorptive capacity. Absorptive capacity is the firm’s ability to acquire, assimilate, transform, and exploit knowledge. Few studies have captured the richness and multi-dimensionality of absorptive capacity, and it remains to be understood how the dimensions of the phenomenon convert knowledge. Furthermore, how absorptive capacity influences the firm remains to be understood. To address these research gaps, this dissertation seeks to (1) determine how absorptive capacity converts knowledge, and (2) determine how absorptive capacity influences firm capabilities. The research questions are investigated using structural modeling techniques to analyze data collected from software-industry firms. The findings offer contributions to the absorptive capacity and capability literatures. For example, absorptive capacity is hypothesized to consist of complex relationships among its internal dimensions. However, findings of this study suggest the relationships among the dimensions are linear in nature. This finding is in line with the theoretical foundations of and …
Date: May 2012
Creator: Daspit, Josh
System: The UNT Digital Library
Academic Advising Professional Characteristics and Standards: Do Academic Advisors Follow Recognized Professional Standards in Their Work? (open access)

Academic Advising Professional Characteristics and Standards: Do Academic Advisors Follow Recognized Professional Standards in Their Work?

There were two main purposes of this quantitative study. The first purpose was to identify characteristics associated with the selected sample of academic advisors that comprise study. Secondly, the study sought to determine how well work related activities of a selected population of academic advisors correlate with professional characteristics constructs and professional standards constructs of academic advising as a profession. The study used Habley’s (1986) characteristics of a profession to derive the studies professional characteristic construct, education activities, research activities, and professional development activities as it relates to a selected group of academic advisors work related activities. The studies professional standards construct was derived from five Council for the Advancement of Standards (CAS) professional standards for academic as it relates to a selected group of academic advisors work related activities. The study of 78 out of 210 identified full-time academic advisors at two-and four-year public colleges and universities in the North Texas Region utilized a multidimensional researcher-developed Web survey instrument designed to measure professional standards and characteristic within the field of academic advising. Study results reinforced current criticism of research and education activities within the field of academic advising showing that the lack of scholarly research and education activities among …
Date: May 2014
Creator: Shelton, Kiesha R.
System: The UNT Digital Library
The Academic and Athletic Experiences of African-american Males in a Division I (Fbs) Football Program (open access)

The Academic and Athletic Experiences of African-american Males in a Division I (Fbs) Football Program

This study investigated the academic and athletic experiences of African-American males in a Division I football bowl subdivision football program. Critical race theory, identity development model, and social learning model were the theoretical frameworks used as the critical lenses in a qualitative design to examine the participants. The participants’ responses were analyzed and interpreted using thematic analysis. A qualitative research design, which included individual interviews with 10 second year African-American male football players, was used to address this research problem. The goal was to bring together both the psychological and sociological perspectives and to challenge participants to candidly describe their academic and athletic experiences and attitudes toward obtaining an undergraduate degree. Four themes were determined in the data analysis: differential treatment and determining oneself, time management, relationships, and career aspirations. In relation to the theoretical frameworks, the development of self-confidence and knowledge of balancing their academic and athletic schedules was critical for all participants. The sense of feeling different and challenged because of the differences in culture and experience was evident. From this study, university and collegiate athletics administrators may better understand the backgrounds, challenges, and learning needs of this population. As a result, higher education personnel may improve the …
Date: December 2013
Creator: Salinas, Silvia M.
System: The UNT Digital Library
Academic and Social Functioning of College Students with Attention-Deficit/Hyperactivity Disorder (ADHD) (open access)

Academic and Social Functioning of College Students with Attention-Deficit/Hyperactivity Disorder (ADHD)

Attention-deficit/hyperactivity disorder (ADHD) is a complicated psychiatric disorder that is typically first diagnosed in childhood and associated with negative outcomes in adulthood such as poor academic performance and difficulties with social relationships. ADHD can be difficult to accurately diagnose in adulthood, given the absence of clear, agreed upon ADHD symptomology in adults. In the current study, two raters used psychometrically sound instruments and diagnostically valid assessment techniques on an archival dataset to create three distinct groups: ADHD [2/3 with other mental health diagnosis (OMH)], OMH only, and no diagnosis. Findings support the value of comprehensive assessment, combined with a thorough evaluation of the material by a trained clinician, for the accurate diagnosis of ADHD for research purposes. Comparisons were made across groups to infer that college students with ADHD have lower grade point averages and academic self-concept than students without mental health diagnoses. Yet, contrary to much of the current literature, college students with ADHD seem to create as strong, deep, supportive and harmonious relationships with loved ones and close friends as their non-diagnosed peers. Clinicians working with college students with ADHD may use the results of the current study to better inform conceptualization, better recognize the innate resilience college …
Date: December 2017
Creator: Calmenson, Nina
System: The UNT Digital Library
Academic Progress Scores to Predict Performance on a State Assessment (open access)

Academic Progress Scores to Predict Performance on a State Assessment

This quantitative study examined seventh-grade reading scores to determine the extent to which certain demographic variables (race/ethnicity, gender, socioeconomic status) explain and MAP reading scores predict reading scores on the State of Texas Assessment of Academic Readiness (STAAR) in a selected northeast Texas public school. Standardized assessments only compare the relative performance of an individual student to other groups of students using scaled scores, which can vary from year to year and from state to state. With the advent of computer adaptive testing, this study provides information on the predictive validity of benchmark assessments. Specifically, this study looked for predictive evidence that indicates how accurately test data can predict criterion scores. Findings revealed, through a multiple regression analysis, that the fall MAP Rasch Unit (RIT) scores predicted the STAAR scale scores. Using SPSS version 22, the data were entered and analyzed in a multiple regression model to determine the presence of a statistical trend or lack thereof. Demographic data and MAP scores were entered into the regression model to examine the predictive validity of the MAP assessment in determining student performance on the STAAR seventh-grade state-mandated reading assessment. The statistical analysis revealed that MAP RIT scores explain a significant variance …
Date: December 2016
Creator: Curry, David Mitchell
System: The UNT Digital Library
Academic Reading Online: Digital Reading Strategies of Graduate-level English Language Learners (open access)

Academic Reading Online: Digital Reading Strategies of Graduate-level English Language Learners

English language learners (ELLs) face many linguistic and cultural challenges in their attempts to succeed academically. They encounter complex academic text, which is increasingly presented online. Although some research has addressed the challenges that university-level ELLs face when reading online texts, almost all of this prior work has focused on undergraduates. The purpose of the current study was to investigate the reading strategies employed by graduate-level ELLs when reading an academic English text online. Participating in the study were four foreign-born doctoral students from different first-language backgrounds—Arabic, Korean, Urdu, and Vietnamese—and the focus was on commonalities as well as differences among them. All four were enrolled in the same doctoral-level course, which included the reading of a specific online academic article as a course requirement. When reading this text individually, each student participated in a think-aloud procedure, followed by post-reading and discourse-based interviews. Analyses included unitizing data from the think-aloud protocols, coding units for strategies employed, and considering related interview commentary and classroom contributions. In their reading, these students made major use of problem-solving strategies, especially reading segments aloud and questioning. They also employed evaluative strategies as well as metacognitive strategies, which included affirming their understanding or indicating lack of …
Date: May 2015
Creator: Knezek, Lois Ann
System: The UNT Digital Library
Academic Self-efficacy of Adult First-generation Students Enrolled in Online Undergraduate Courses (open access)

Academic Self-efficacy of Adult First-generation Students Enrolled in Online Undergraduate Courses

This study examined differences between adult first-generation (AFG) and adult-continuing generation (ACG) students’ academic self-efficacy with regard to the online courses in which they were currently enrolled. The study used an online survey methodology to collect self-reported quantitative data from 1,768 undergraduate students enrolled in an online course at a mid-sized, four-year public university in the southwestern United States; 325 cases were usable for the study. The t-tests revealed no statistically significant differences between the academic self-efficacy of the AFG and ACG students. Parents’ level of educational attainment was unrelated to adult students’ academic self-efficacy with online courses. Ordinary least-squares analysis was used to evaluate student characteristics that might be associated with academic self-efficacy in the online environment. A combination of gender, GPA, age, race/ethnicity (White, Black, Hispanic, and other), and number of previous online courses predicted a statistically significant 12% of the variance in academic self-efficacy in an online environment (p < .001). Age (p < .001) and self-efficacy were positively correlated, meaning that adult students reported greater academic self-efficacy than did younger students; and number of previous online courses (p < .001) was also positively correlated to academic self-efficacy, indicating that students with greater experience with online courses …
Date: August 2014
Creator: Jackson, Delores
System: The UNT Digital Library
Academic, Social and Emotional Functioning of College Students with Attention-Deficit/Hyperactivity Disorder (ADHD) (open access)

Academic, Social and Emotional Functioning of College Students with Attention-Deficit/Hyperactivity Disorder (ADHD)

Attention deficit/hyperactivity disorder (ADHD) is frequently associated with negative occupational, social and psychological outcomes among community samples of adults; as such, it is expected that college students with ADHD face similar struggles. The research targeting this group of individuals, however, is sparse and tempered by significant limitations. The current study aimed to address methodological limitations in the current literature by including instruments to formally diagnosis ADHD and comorbid disorders, utilizing psychometrically sound instruments and comparing functioning of college students with ADHD across gender and subtype. It was hypothesized that participants with ADHD would report lower GPAs, higher levels of emotional distress and negative relationship characteristics than participants without ADHD. It was also hypothesized that participants with ADHD-combined type (ADHD-C) would report higher levels of substance and alcohol use than participants with ADHD-predominately inattentive type (ADHD-I), and that participants with ADHD-I would report higher levels of anxiety and depression than participants with ADHD-C. Women diagnosed with ADHD were expected to report higher levels of anxiety and depression than men diagnosed with ADHD; whereas, men diagnosed with ADHD were expected to report higher levels of substance and alcohol use than women. MANOVA, ANOVA and Mann-Whitney U tests were conducted to test hypotheses. …
Date: August 2015
Creator: McKelvy, Tara N.
System: The UNT Digital Library
The Academic Steroid: Nonmedical Use of Prescription Stimulants at a North Texas University (open access)

The Academic Steroid: Nonmedical Use of Prescription Stimulants at a North Texas University

The goal of this study was to determine the extent, motivations, and justifications of nonmedical prescription stimulant use among the population at a large public university in the North Texas region. Participants consisted of 526 undergraduate students enrolled at the studied university during the spring and summer 2014 semesters. The findings of the study suggest that the nonmedical use by students was higher than the findings in much of the current literature, but was within the parameters established in the literature. The primary motivation for nonmedical use was academic in nature and was justified by moderation of nonmedical use to strategic academic times.
Date: December 2014
Creator: Pennington, Cody W.
System: The UNT Digital Library
Academic Stress in Student-Athletes (open access)

Academic Stress in Student-Athletes

Academic stress and the causes of such stress are subjects that are found in very few studies concerning student-athletes. Therefore, the purpose of this quantitative study is to determine how the following variables relate to academic stress and perceived stress either through correlations or differences--demographics, academic classification, major or field of study, athletic scholarship status, and season of sport (in- season/ out of season). An online questionnaire containing a Perceived Stress Scale and a Perception of Academic Stress scale were distributed to 151 student-athlete participants at a university in the southwest United States. The results indicated that biological sex has a significant relationship to perceived stress. No other variables were found significant to perceived stress or academic stress.
Date: May 2017
Creator: James, Christina
System: The UNT Digital Library
Accelerated Corrosion Test with Operation Simulation of All-Aluminum Microchannel Heat Exchangers (open access)

Accelerated Corrosion Test with Operation Simulation of All-Aluminum Microchannel Heat Exchangers

The HVAC&R industry is looking to transition from copper-aluminum heat exchangers to all-aluminum microchannel technology. The want for the transition stemmed from seeing the performance improvement of all-aluminum microchannel radiators in the automotive industry. Applications differ between the two industries; therefore, applying this technology for HVAC&R use must be validated. Research towards operating modes of an all-aluminum heat exchanger in a defined corrosive environment will provide the industry with a better understanding of heat exchanger design and heat exchanger material selection. The worth in this is preventing overdesign and producing more efficient heat exchangers. Furthermore, ASHRAE members and the corrosion community will find value in a defined corrosion system and corrosion test procedure. The information gained through past research has progressed assessment of material performance; however, the methods improperly simulate and expedite natural weathering. The most common method being used is the ASTM (American Society of Testing Materials) Sea Water Acetic Acid Test. The research discussed in this paper was focused on improving a standard corrosion system by implementing system modifications to simulate heat exchanger operation while performing a modified wet-dry cyclic test (e.g. ASTM G85 Annex 5). The goal is to produce results that are more representative of natural …
Date: May 2016
Creator: Vaughan, Haydn
System: The UNT Digital Library