You limited your search to:

  Partner: UNT Libraries
 Decade: 1990-1999
 Collection: UNT Theses and Dissertations
Cure kinetics and processing parameters of neat and reinforced high performance epoxy resins : evaluation of techniques

Cure kinetics and processing parameters of neat and reinforced high performance epoxy resins : evaluation of techniques

Access: Use of this item is restricted to the UNT Community.
Date: December 1999
Creator: Bilyeu, Bryan
Description: Kinetic equation parameters for the curing reaction of a commercial glass fiber reinforced high performance epoxy prepreg composed of the tetrafunctional epoxy tetraglycidyl 4,4-diaminodiphenyl methane (TGDDM), the tetrafunctional amine curing agent 4,4Â’-diaminodiphenylsulfone (DDS) and an ionic initiator/accelerator, are determined by various thermal analysis techniques and the results compared. The reaction is monitored by heat generated determined by differential scanning calorimetry (DSC). The changes in physical properties indicating increasing conversion are followed by shifts in glass transition temperature determined by DSC and temperature-modulated DSC (TMDSC), thermomechanical (TMA) and dynamic mechanical (DMA) analysis and thermally stimulated depolarization (TSD). Changes in viscosity, also indicative of degree of conversion, are monitored by DMA. Thermal stability as a function of degree of cure is monitored by thermogravimetric analysis (TGA). The parameters of the general kinetic equations, including activation energy and rate constant, are explained and used to compare results of various techniques. The utilities of the kinetic descriptions are demonstrated in the construction of a useful time-temperature-transformation (TTT) diagram for rapid determination of processing parameters in the processing of prepregs. Copyright is held by the author, unless otherwise noted. All rights reserved. Files: Thesis.pdf Special Conditions
Contributing Partner: UNT Libraries
As Darkness Falls: A Composition for Wind Ensemble

As Darkness Falls: A Composition for Wind Ensemble

Access: Use of this item is restricted to the UNT Community.
Date: December 1999
Creator: Prinz, Kendall R.
Description: As Darkness Falls is a composition that explores our interaction with several aspects of darkness through the use of musical imagery. The imagery attempts to reflect the moods, feelings, and impressions of a person as he or she interacts with darkness. The non-programmatic character of the composition allows listeners to superimpose their own experiences onto the musical tapestry in order to manifest a personal connection between the listener and the music. As Darkness Falls is a composition scored for a minimum instrumentation of piccolo, 6 flutes, 3 oboes, 3 bassoons, 9 B-flat clarinets, B-flat bass clarinet, 2 E-flat alto saxophones, B-flat tenor saxophone, E-flat baritone saxophone, 4 B-flat trumpets, 4 horns in F, 3 tenor trombones, bass trombone, 2 euphoniums, 2 tubas, timpani, and 4 percussionists. The music consists of three movements (slow-slow-fast) lasting a total of approximately seventeen minutes. The duration of each of the three movements is six minutes, four and one-half minutes, and six and one-half minutes, respectively. The document also contains an analysis of the work by the composer. The analysis explores the compositional style of the work, focusing on musical aspects within each movement that were governing parameters in the compositional process.
Contributing Partner: UNT Libraries
A descriptive study of students who were accepted for admission at West Texas A&M University but did not enroll

A descriptive study of students who were accepted for admission at West Texas A&M University but did not enroll

Access: Use of this item is restricted to the UNT Community.
Date: December 1999
Creator: Barton, Mary Edna
Description: Each year, institutions of higher education devote valuable financial and personnel resources in the hope of enhancing student recruitment and matriculation. The purpose of this study was to examine the demographic characteristics, the factors that influenced studentsÂ’ decisions to apply for admission to a university, their educational intentions, and their reasons for not enrolling after they had been admitted. The subjects of the study were first-time freshmen accepted for admission to a mid-size, public, southwestern university who did not enroll for the fall 1997 semester. Statistically significant differences were found when comparing no-shows and enrolled students by gender, ethnicity, age, ACT/SAT score, and distance of their hometown from the university. There were more female no-shows, and more males enrolled than females; a greater percentage of no-shows reported the distance of their hometown to be more than 200 miles; and the mean test score for no-shows was higher. Factors important in the college selection process found to be statistically significant among the groups were: a greater percentage of Minorities than Caucasians reported the importance of the financial aid award or a scholarship offer; students living within 100 miles of the campus reported the proximity of the university as important, advice received ...
Contributing Partner: UNT Libraries
Development of a coaxiality indicator

Development of a coaxiality indicator

Access: Use of this item is restricted to the UNT Community.
Date: December 1999
Creator: Arendsee, Wayne C.
Description: The geometric dimensioning and tolerancing concept of coaxiality is often required by design engineers for balance of rotating parts and precision mating parts. In current practice, it is difficult for manufacturers to measure coaxiality quickly and inexpensively. This study examines feasibility of a manually-operated, mechanical device combined with formulae to indicate coaxiality of a test specimen. The author designs, fabricates, and tests the system for measuring coaxiality of holes machined in a steel test piece. Gage Repeatability and Reproducibility (gage R&R) and univariate analysis of variance is performed in accordance with Measurement System Analysis published by AIAG. Results indicate significant design flaws exist in the current configuration of the device; observed values vary greatly with operator technique. Suggestions for device improvements conclude the research.
Contributing Partner: UNT Libraries
Ecological Enhancement of Timber Growth: Applying Compost to Loblolly Pine Plantations

Ecological Enhancement of Timber Growth: Applying Compost to Loblolly Pine Plantations

Access: Use of this item is restricted to the UNT Community.
Date: December 1999
Creator: Stuckey, Harold Troy
Description: This study explored the application of compost onto a small loblolly pine tree forest in northeast Texas. Its purpose was to determine if the application of various amounts of compost would provide for accelerated rates of growth for the trees. Soil parameters were also monitored. A total of 270 trees were planted and studied in a northeast Texas forest ecosystem. Compost rates of 5, 25, and 50 tons per acre with either soil or compost backfill were utilized and compared to a control without compost. Nonparametric and parametric ANOVA and Chi-Square tests were utilized. The results indicated that greater application rates retained greater moisture and higher pH levels in the soil. Compost applications also yielded a greater survival rate as well as larger tree height and diameter when compared to the control. The 25 ton/acre application backfilled in native soil achieved the greatest average in height and diameter when compared to the averages for the control plot. Greater growth differences for the 25S application can be attributed to additional nutrients coupled with a stable pH consistent with native soil acidity.
Contributing Partner: UNT Libraries
The effects of a tactile prompting device on the requesting behavior of a child with autism

The effects of a tactile prompting device on the requesting behavior of a child with autism

Date: December 1999
Creator: Russo, Lori A.
Description: In the present experiment, a remote control tactile prompting device (RCT) was utilized to prompt a child with autism to recruit teacher models and play suggestions. A multiple baseline and reversal was used to assess the effects of the RCT across three play contexts. The results showed increases in the number of requests for models and suggestions as well as increases in the duration of interactive play between the child and therapist, the number of contextual statements emitted by the child, and the topography and contexts of the play behaviors emitted by the child. Findings are discussed in terms of the effectiveness and generality of the RCT and the issue of teaching a child to recruit versus teaching a child activity-specific behaviors.
Contributing Partner: UNT Libraries
The Effects of Age, Sex, and Class Stratification and the Use of Health Care Services among Older Adults in the United Kingdom

The Effects of Age, Sex, and Class Stratification and the Use of Health Care Services among Older Adults in the United Kingdom

Date: December 1999
Creator: Carter, Holly R.
Description: As the population ages, providing health services for the growing number of older people will become an increasingly difficult problem. In countries where the health services are provided by the government, these problems are involved with complicated issues of finance and ethics. This is the case of the National Health Service, the government institution providing health care for the citizens of the United Kingdom. Knowing what social factors influence health care usage can be a link to match usage and funding. Literature has shown that health care utilization can be predicted by social factors, as well as the medical model, and from this orientation social variables were drawn from the 1994 General Household Survey. Social factors were analyzed to determine relationships that exist between certain types of health care use and these factors. Age, sex, and class, the three main factors shown in literature to affect usage, were then analyzed to determine if services are allocated on the basis of these factors or the basis of need from illness and disability. Results of the study show that of the predisposing variables, age, sex, and class, are associated with most types of health care use. From the enabling variables, both source ...
Contributing Partner: UNT Libraries
The Effects of Shaping and Instruction-based Procedures on Behavioral Variability during Acquisition and Extinction

The Effects of Shaping and Instruction-based Procedures on Behavioral Variability during Acquisition and Extinction

Date: December 1999
Creator: McCary, Donald
Description: This study examined effects of two response acquisition procedures on topography of responding using the revealed operant technique and compared results to previous experiments on this topic. Subjects emitted 100 repetitions each of 4 response patterns on a continuous schedule of reinforcement. A 30-min extinction condition followed acquisition. One group of subjects learned the first response through a series of shaping steps designed to reduce acquisition variability. Another group of subjects was instructed in the correct response topography and was told there was no penalty for attempting other sequences. The first group of subjects produced high variability during extinction despite reduced variability in acquisition. The second group of subjects responded with moderate to high variability during extinction and little variability during acquisition. Most extinction responses for the first group were variations of the last pattern reinforced. Most extinction responses for the second group were repetitions of the last pattern reinforced.
Contributing Partner: UNT Libraries
Elasticity of money as a reinforcer: Assessing multiple compositions of unit price

Elasticity of money as a reinforcer: Assessing multiple compositions of unit price

Date: December 1999
Creator: Viken, Kjetil
Description: Behavioral economics is the integration of concepts from micro-economics into behavior analysis. Most of the research in behavioral economics has been done with non-human subjects and with drugs as reinforcers. This study represents an extension of previous research to assess money as a reinforcer with humans as subjects. The participants in this study solved math problems to earn money at various unit prices. Results indicate that demand of money adhered to the law of demand in that consumption decreased as unit prices increased. An underlying assumption is that consumption should be equivalent at different compositions of unit price. Replications of either the same or different compositions of unit price indicated that there were some discrepancies in consumption in this study.
Contributing Partner: UNT Libraries
Empowerment: The Paradigm for Success for the Nursing Homes of the 21st Century

Empowerment: The Paradigm for Success for the Nursing Homes of the 21st Century

Access: Use of this item is restricted to the UNT Community.
Date: December 1999
Creator: Connorton, Margaret L.
Description: For a workplace to be successful, it needs to have a higher morale, thus leading to higher quality of care for residents. For a workplace to be successful in empowerment, it must have developed strong teams, and everyone must work as a team and respect one another. The research for this paper focused on many issues. The most important part of my research came from a study of the nursing assistants at Jennings Hall (JH) in Garfield, Ohio. From the data received, I concluded that the two biggest problems in many nursing homes are lack of respect and lack of team-centered attitude.
Contributing Partner: UNT Libraries