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 Degree Level: Doctoral
 Collection: UNT Theses and Dissertations
Joint Schemes for Physical Layer Security and Error Correction

Joint Schemes for Physical Layer Security and Error Correction

Date: August 2011
Creator: Adamo, Oluwayomi Bamidele
Description: The major challenges facing resource constraint wireless devices are error resilience, security and speed. Three joint schemes are presented in this research which could be broadly divided into error correction based and cipher based. The error correction based ciphers take advantage of the properties of LDPC codes and Nordstrom Robinson code. A cipher-based cryptosystem is also presented in this research. The complexity of this scheme is reduced compared to conventional schemes. The securities of the ciphers are analyzed against known-plaintext and chosen-plaintext attacks and are found to be secure. Randomization test was also conducted on these schemes and the results are presented. For the proof of concept, the schemes were implemented in software and hardware and these shows a reduction in hardware usage compared to conventional schemes. As a result, joint schemes for error correction and security provide security to the physical layer of wireless communication systems, a layer in the protocol stack where currently little or no security is implemented. In this physical layer security approach, the properties of powerful error correcting codes are exploited to deliver reliability to the intended parties, high security against eavesdroppers and efficiency in communication system. The notion of a highly secure and reliable ...
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A Differential Study of Reasons Why Students Drop Out of School as Related to Actual Dropout-preventive Practices of a Metropolitan School District

A Differential Study of Reasons Why Students Drop Out of School as Related to Actual Dropout-preventive Practices of a Metropolitan School District

Date: August 1972
Creator: Adams, Ambrose Davidson, 1936-
Description: The problem of this study was the differentiation of high schools in a metropolitan school district from the standpoint of the measures taken to prevent student dropouts.
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The Relationship Between Supplemental Instruction Leader Learning Style and Study Session Design

The Relationship Between Supplemental Instruction Leader Learning Style and Study Session Design

Date: May 2011
Creator: Adams, Joshua
Description: The purpose of this qualitative study was to examine the learning styles of supplemental instruction leaders at a large, public university during the fall 2010 semester and determine whether or not their personal learning styles influenced the way they designed and developed out-of-class study sessions. The total population of supplemental instruction leaders was 37, of which 24 were eligible to participate in the study. Of the 24 eligible supplemental instruction leaders, 20 completed the entire study. Participants in the study included nine male and 11 female supplemental instruction leaders with a median age of 22.25 years-old. Seventeen participants indicated their classification as senior, two as junior, and one as sophomore. Of the participants, 16 indicated white as a race or ethnicity, one indicated Asian, two indicated African American, and one indicated both American Indian/Alaska Native and white. Supplemental instruction leader learning style was assessed using the Kolb Learning Style Inventory. Leaders were then interviewed, and their study sessions were analyzed. Through triangulation of data from learning style, interviews and actual study session documents, four major themes emerged. The four themes were: 1) incorporation of personal experience into study session design, 2) the sense of impact on student learning, 3) a ...
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The Effects of Interactive Reviews and Learning Style on Student Learning Outcomes at a Texas State University

The Effects of Interactive Reviews and Learning Style on Student Learning Outcomes at a Texas State University

Date: May 2008
Creator: Adams, Wesley
Description: This study investigated the effects of interactive lessons and learning style on student learning outcomes in self-defense education classes. The study utilized an experimental design that incorporated four self-defense education classes at the University of North Texas (UNT) during the fall semester 2007 (N = 87). A pre-test was administered during the first week of class to determine prior knowledge of the participants. The Visual Auditory Reading/Kinesthetic Inventory (VARK) was used to assess the learning styles of the students and was completed after the pre-test of knowledge was administered. The treatment group received the interactive lesson and the control received a paper review. The difference between the pre and posttest was used as a measure of improvement of the student's learning outcomes. A 2 (treatment/control) by 2 (pretest/posttest) ANOVA with repeated measures was conducted to examine the differential improvement in knowledge across the intervention. Based on the 2-way ANOVA there was a significant difference between the treatment group and the control group based on their learning outcomes. A repeated measures ANOVA was conducted to determine if there was a significant difference between the groups based on the pre and post test scores. Based on the results of a one week ...
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High-temperature corrosion of aluminum alloys: Oxide-alloy interactions and sulfur interface chemistry

High-temperature corrosion of aluminum alloys: Oxide-alloy interactions and sulfur interface chemistry

Date: December 2000
Creator: Addepalli, Swarnagowri
Description: The spallation of aluminum, chromium, and iron oxide scales is a chronic problem that critically impacts technological applications like aerospace, power plant operation, catalysis, petrochemical industry, and the fabrication of composite materials. The presence of interfacial impurities, mainly sulfur, has been reported to accelerate spallation, thereby promoting the high-temperature corrosion of metals and alloys. The precise mechanism for sulfur-induced destruction of oxides, however, is ambiguous. The objective of the present research is to elucidate the microscopic mechanism for the high-temperature corrosion of aluminum alloys in the presence of sulfur. Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM) studies were conducted under ultrahigh vacuum (UHV) conditions on oxidized sulfur-free and sulfur-modified Al/Fe and Ni3Al(111). Evaporative deposition of aluminum onto a sulfur-covered iron surface results in the insertion of aluminum between the sulfur adlayer and the substrate, producing an Fe-Al-S interface. Aluminum oxidation at 300 K is retarded in the presence of sulfur. Oxide destabilization, and the formation of metallic aluminum are observed at temperatures > 600 K when sulfur is located at the Al2O3-Fe interface, while the sulfur-free interface is stable up to 900 K. In contrast, the thermal stability (up to at least 1100 ...
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An analysis of the Sonata for Trumpet and Piano by Peter Maxwell Davies, identifying the use of historical forms, and the implications for performance.

An analysis of the Sonata for Trumpet and Piano by Peter Maxwell Davies, identifying the use of historical forms, and the implications for performance.

Access: Use of this item is restricted to the UNT Community.
Date: August 2006
Creator: Adduci, Kathryn James
Description: The Sonata for Trumpet and Piano by Peter Maxwell Davies is one of his earliest works, and a notoriously difficult work to perform. While using serialism and other twentieth-century compositional techniques, this work also uses older historical forms, including sonata-allegro and sonata-rondo forms. An analysis of the work is presented, identifying the older historical forms, and considerations for performers when making decisions on how to perform the work are provided.
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Dynamic Measurement of Intraoral Pressure and Sound Pressure With Laryngoscopic Characterization During Oboe Performance

Dynamic Measurement of Intraoral Pressure and Sound Pressure With Laryngoscopic Characterization During Oboe Performance

Date: December 2011
Creator: Adduci, Michael Douglas
Description: Measurements of intraoral pressure (IOP) and sound pressure level (SPL) were taken of four oboists as they performed two sets of musical exercises: (1) crescendo-decrescendo from pp to ff and back to pp on the pitches D4, G4, C5 and A5, and (2) straight and vibrato performances of the same four pitches at mf. Video images of the vocal tract were also made using flexible fiberoptic nasoendoscopy (FFN). IOP and SPL data were captured in real time by the WinDaq®/Lite software package, with the dB meter located 8-9 inches in directly front of the oboe bell. The study yielded minimum and maximum values from 21.04 to 57.81 mm Hg and from 65.53 to 100.89 dB across all pitches examined. Discussion is included for the following topics: (1) the oboe’s sound envelope, or functional range of IOP and SPL values at different pitch levels, including the nonlinearity in the relationship between IOP and SPL on the oboe, (2) the static activation and kinetic maintenance thresholds for reed vibration, (3) the effect of vibrato on IOP/SPL, (4) the utilization of the vocal tract during execution of dynamic changes and vibrato, and (5) the impact of player experience on control of physical variables.
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Teacher Turnover among Teachers of Students with Emotional and Behavior Disorders

Teacher Turnover among Teachers of Students with Emotional and Behavior Disorders

Date: December 2007
Creator: Adera, Beatrice Atieno
Description: The purpose of this study was to investigate factors that compel teachers of students with emotional and behavioral disorders (E/BD) to quit or stay in their job. Invitations to participate in the study were sent to a sample of educators from each the four census regions of the United States who currently work or have worked in the past worked with students with E/BD and have participated in one or more of the Council for Children with Behavioral Disorders (CCBD) professional development events. A total of 156 educators responded to the online survey and 9 participated in the focus groups. Quantitative information generated from the survey was analyzed using frequency distributions and ANOVA, whereas, qualitative information were analyzed by summarizing and sorting information into different categories. The results were presented in narrative and tabular form and organized in response to each of the research questions. The projected high teacher turnover as depicted in the findings, were mainly attributed to workplace variables and classroom conditions. Both variables are likely to be associated with high levels of dissatisfaction and lack of commitment eventually leading to decisions by teachers of students with E/BD to leave their job. Most respondents perceived themselves as being ...
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Proteomic Responses in the Gill of Zebrafish Following Exposure to Ibuprofen and Naproxen

Proteomic Responses in the Gill of Zebrafish Following Exposure to Ibuprofen and Naproxen

Date: August 2012
Creator: Adhikari, Prem R.
Description: Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most abundant environmental pharmaceutical contaminants. In this study, a proteomic analysis was conducted to identify proteins differentially expressed in gill tissue of zebrafish (Danio rerio) after a 14-day exposure to the NSAIDs ibuprofen or naproxen. A total of 104 proteins with altered expression as indicated by 2-dimensional electrophoresis were analyzed by liquid chromatography with ion trap mass spectrometry (MS/MS). A total of 14 proteins fulfilled our requirements for identification which included consistency among replicate gels as well as successful MS/MS ion searches with the MASCOT database. The most prominent feature of the differential protein expression observed after NSAID exposure was an up-regulation of proteins belonging to the globin family which are involved in the transport of oxygen from gills and availability of heme molecules required for synthesis of cyclooxygenase. Differential expression was observed at exposure concentrations as low as 1-10 µg/L indicating that altered gene expression may occur in fish subjected to environmentally realistic levels of NSAID exposure.
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An analysis of job satisfaction for special educators who instruct students with emotional/behavioral disorders: How working conditions impact commitment.

An analysis of job satisfaction for special educators who instruct students with emotional/behavioral disorders: How working conditions impact commitment.

Date: August 2009
Creator: Adkins, Beverly
Description: Teachers of students with emotional/behavioral disorders (E/BD) find that myriad concerns for effective teaching (e.g., salaries, increased paperwork, classroom management) challenge their ability to meet personal and professional needs. The push for certified teachers and limited training to work with students with special needs create stressors that can prohibit effective teaching in the workplace. Teacher moral drops and half of newly hired employees leave the profession. Equally important, student outcomes are affected. Demographic information, program practices, and commitment information from special education teachers across the country were examined in this study. These areas of study helped to determine the best indicators for teacher job satisfaction and barriers that threaten satisfactory working conditions. An online survey was designed to capture 29 areas to explore qualifications and working environments for these teachers. Of the 600 targeted teachers, 332 individuals participated in Likert-like scales to determine their degree of satisfaction or dissatisfaction for working conditions, use of intervention strategies, and areas of commitment. Closed-ended and multiple-choice questions were used. Descriptive analyses and tables aided in understanding this study. The resulting factors indicated that, although some respondents pointed to job dissatisfaction within the subset of questions, participants who worked for more than 6 years ...
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