UNT Theses and Dissertations - 123 Matching Results

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

Description: 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 indicate severe non-dynamical correlation. The diagnostic is only weakly sensitive to the basis set (beyond polarized double zeta) and can be applied to problems beyond practical reach of wavefunction ab-initio methods required for other diagnostics.
Date: August 2013
Creator: Fogueri, Uma
Partner: UNT Libraries

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

Description: 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.
Partner: UNT Libraries

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

Description: 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 corrosion behavior and its forms. Current results were gathered from five of ten samples that underwent initial testing. Finally, possible improvements towards the chamber system and the test method, including the salt solution, are discussed.
Date: May 2016
Creator: Vaughan, Haydn
Partner: UNT Libraries

Acute Effects of the Antibiotic Streptomycin on Neural Network Activity and Pharmacological Responses

Description: The purpose of this study is to find out that if antibiotic streptomycin decreases neuronal network activity or affects the pharmacological responses. The experiments in this study were conducted via MEA (multi-electrode array) technology which records neuronal activity from devices that have multiple small electrodes, serve as neural interfaces connecting neurons to electronic circuitry. The result of this study shows that streptomycin lowered the spike production of neuronal network, and also, sensitization was seen when neuronal network pre-exposed to streptomycin.
Date: December 2014
Creator: Zeng, Wei Rong
Partner: UNT Libraries

Adhesion and Surface Energy Profiles of Large-area Atomic Layers of Two-dimensional MoS2 on Rigid Substrates by Facile Methods

Description: Two-dimensional (2D) transition metal dichalcogenides (TMDs) show great potential for the future electronics, optoelectronics and energy applications. But, the studies unveiling their interactions with the host substrates are sparse and limits their practical use for real device applications. We report the facile nano-scratch method to determine the adhesion energy of the wafer scale MoS2 atomic layers attached to the SiO2/Si and sapphire substrates. The practical adhesion energy of monolayer MoS2 on the SiO2/Si substrate is 7.78 J/m2. The practical adhesion energy was found to be an increasing function of the MoS2 thickness. Unlike SiO2/Si substrates, MoS2 films grown on the sapphire possess higher bonding energy, which is attributed to the defect-free growth and less number of grain boundaries, as well as less stress and strain stored at the interface owing to the similarity of Thermal Expansion Coefficient (TEC) between MoS2 films and sapphire substrate. Furthermore, we calculated the surface free energy of 2D MoS2 by the facile contact angle measurements and Neumann model fitting. A surface free energy ~85.3 mJ/m2 in few layers thick MoS2 manifests the hydrophilic nature of 2D MoS2. The high surface energy of MoS2 helps explain the good bonding strength at MoS2/substrate interface. This simple adhesion energy and surface energy measurement methodology could further apply to other TMDs for their widespread use.
Date: May 2016
Creator: Wu, Min
Partner: UNT Libraries

Angular Analysis of a Wide-Band Energy Harvester based on Mutually Perpendicular Vibrating Piezoelectric Beams

Description: The recent advancements in electronics and the advents of small scaled instruments has increased the attachment of life and functionality of devices to electrical power sources but at the same time granted the engineers and companies the ability to use smaller sources of power and batteries. Therefore, many scientists have tried to come up with new solutions for a power alternatives. Piezoelectric is a promising material which can readily produce continuous electric power from mechanical inputs. However, their power output is dependent upon several factors such as, system natural frequency, their position in the system, the direction of vibration and many other internal and external factors. In this research the working bandwidth of the system is increased through utilizing of two different piezoelectric beam in different directions. The dependency of output power with respect to rotation angle and also the frequency shift due to the rotation angle is studied.
Date: December 2016
Creator: Mirzaabedini, Sohrab
Partner: UNT Libraries

“The Angular Degrees of Freedom” and Other Stories

Description: The preface, " Performing Brain Surgery: The Problematic Nature of Endings in Short Fiction," deals with the many and varied difficulties short story writers encounter when attempting to craft endings. Beginning with Raymond Carver and Flannery O’Connor and moving to my own work, I discuss some of the obscure criteria used to designate a successful ending, as well as the more concrete idea of the ending as a unifying element. Five short stories make up the remainder of this thesis: "In-between Girls," "Crocodile Man," "Surprising Things, Sometimes Amusing," "Good Jewelry," and "The Angular Degrees of Freedom."
Date: December 2014
Creator: Feagin, Aprell McQueeney
Partner: UNT Libraries

Application of Cyclic Polarization of Aluminum 3003 Used in All-Aluminum Microchannel Heat Exchangers

Description: All-aluminum microchannel heat exchangers are designed to significantly reduce refrigerant charge requirements, weight, reduced brazed joints, and decreased potential for leakage by increasing reliability. Al 3003 alloy is corrosion resistant and can be formed, welded, and brazed but the issue with all-aluminum heat exchangers is localized corrosion (pitting) in corrosive environments. Currently, there is no universally accepted corrosion test that all coil manufacturers use to characterize their products. Electrochemical testing method of cyclic polarization was employed in this investigation and relevant parameters including electrolyte corrosive agent and its concentration, electrolyte pH, and applied potential scan rate was varied to find an optimal set of parameters. Results of cyclic polarization of Al 3003 in electrolytes containing various concentrations of NaCl were compared with those of the tests in Sea Water Acidified Accelerated Test (SWAAT) electrolyte and it is shown the SWAAT electrolyte (4.2% sea salt acidified to pH of 2.9) is by far stronger (in terms of corrosivity) than typical 3.5% NaCl solution used in most corrosion testing. Corrosion rates (g/m2yr) of Al 3003 measured in this investigation were comparable to those provided by ISO 9223 standard corresponding to C1 through CX categories. Duration of cyclic polarization test is much shorter than that of SWAAT and results obtained in this test is more reproducible compared to those of SWAAT. Scanning electron microscopy micrographs show typical pit depths of about 50 μm.
Date: May 2015
Creator: Barnes, Javier
Partner: UNT Libraries

Application of UV-Vis Spectroscopy to the Monitoring, Characterization and Analysis of Chemical Equilibria of Copper Etching Baths

Description: The continuously increasing demand for innovation in the miniaturization of microelectronics has driven the need for ever more precise fabrication strategies for device packaging, especially for printed circuit boards (PCBs). Subtractive copper etching is a fundamental step in the fabrication process, requiring very precise control of etch rate and etch factor. Changes in the etching chemical equilibrium have significant effects on etching behavior, and CuCl2 / HCl etching baths are typically monitored with several parameters including oxidation-reduction potential, conductivity, and specific gravity. However, the etch rate and etch factor can be difficult to control even under strict engineering controls of those monitoring parameters. The mechanism of acidic cupric chloride etching, regeneration and recovery is complex, and the current monitoring strategies can have difficulty controlling the interlocking chemical equilibria. A complimentary tool, thin-film UV-Vis spectroscopy, can be utilized to improve the current monitoring strategies, as UV-Vis is capable of identifying and predicting etching behavior that the current standard methodologies have difficulty predicting. Furthermore, as a chemically-sensitive probe, UV-Vis can investigate the complex changes to the chemical equilibrium and speciation of the etch bath, and can contribute overall to significant improvements in the control of the copper etching system in order to meet the demands of next-level design strategies.
Date: August 2017
Creator: Lambert, Alexander S
Partner: UNT Libraries

Bioinspired and biocompatible coatings of poly(butylene adipate-co-terephthalate) and layer double hydroxide composites for corrosion resistance

Description: Hierarchical arrangement of biological composites such as nacre and bone containing high filler (ceramic) content results in high strength and toughness of the natural material. In this study we mimic the design of layered bone microstructure and fabricate an optimal multifunctional bio-nanocomposite having strength, toughness and corrosion resistance. Poly (butylene adipate-co-terephthalate) (PBAT), a biodegradable polymer was used as a substrate material with the reinforcement of LDH (Layered double hydroxide) as a nanofiller in different concentrations to achieve enhancement in mechanical properties as well as processing related thermostability. Corrosion resistance was increased by mimicking a layered structured which incorporated a tortuous diffusion path.
Date: May 2016
Creator: Rizvi, Syed Hussain
Partner: UNT Libraries

Brain Computer Interface (BCI) Applications: Privacy Threats and Countermeasures

Description: In recent years, brain computer interfaces (BCIs) have gained popularity in non-medical domains such as the gaming, entertainment, personal health, and marketing industries. A growing number of companies offer various inexpensive consumer grade BCIs and some of these companies have recently introduced the concept of BCI "App stores" in order to facilitate the expansion of BCI applications and provide software development kits (SDKs) for other developers to create new applications for their devices. The BCI applications access to users' unique brainwave signals, which consequently allows them to make inferences about users' thoughts and mental processes. Since there are no specific standards that govern the development of BCI applications, its users are at the risk of privacy breaches. In this work, we perform first comprehensive analysis of BCI App stores including software development kits (SDKs), application programming interfaces (APIs), and BCI applications w.r.t privacy issues. The goal is to understand the way brainwave signals are handled by BCI applications and what threats to the privacy of users exist. Our findings show that most applications have unrestricted access to users' brainwave signals and can easily extract private information about their users without them even noticing. We discuss potential privacy threats posed by current practices used in BCI App stores and then describe some countermeasures that could be used to mitigate the privacy threats. Also, develop a prototype which gives the BCI app users a choice to restrict their brain signal dynamically.
Date: May 2017
Creator: Bhalotiya, Anuj Arun
Partner: UNT Libraries

Can Observing Behavior Predict Performance in Conditional Discriminations?

Description: Prompts are implemented often in training procedures, to include conditional discriminations, and this can lead to prompt dependency. The current study extends a prior study that suggested that the effectiveness of supplementary visual stimuli displaying the sample and comparison was dependent on the timing in relation to the selection task, presented as a prompt or feedback, in a match-to-sample procedure. The current research examines if the differences in that effectiveness were due to differences in observing behavior in those two conditions. Measures of observing behavior were determined by making access to the individual visual stimuli contingent on clicking on the visual stimulus and keeping the cursor located on the stimulus. Participants viewed the sample comparison much less than the comparison stimulus in both the prompt and feedback conditions. Latency to select the comparison stimulus was much shorter for the prompt condition suggesting that the participants might have interacted differently with the selection task in the two conditions.
Date: December 2016
Creator: Marchini, Kevin Julian
Partner: UNT Libraries

Case Studies to Learn Human Mapping Strategies in a Variety of Coarse-Grained Reconfigurable Architectures

Description: Computer hardware and algorithm design have seen significant progress over the years. It is also seen that there are several domains in which humans are more efficient than computers. For example in image recognition, image tagging, natural language understanding and processing, humans often find complicated algorithms quite easy to grasp. This thesis presents the different case studies to learn human mapping strategy to solve the mapping problem in the area of coarse-grained reconfigurable architectures (CGRAs). To achieve optimum level performance and consume less energy in CGRAs, place and route problem has always been a major concern. Making use of human characteristics can be helpful in problems as such, through pattern recognition and experience. Therefore to conduct the case studies a computer mapping game called UNTANGLED was analyzed as a medium to convey insights of human mapping strategies in a variety of architectures. The purpose of this research was to learn from humans so that we can come up with better algorithms to outperform the existing algorithms. We observed how human strategies vary as we present them with different architectures, different architectures with constraints, different visualization as well as how the quality of solution changes with experience. In this work all the case studies obtained from exploiting human strategies provide useful feedback that can improve upon existing algorithms. These insights can be adapted to find the best architectural solution for a particular domain and for future research directions for mapping onto mesh-and- stripe based CGRAs.
Date: May 2017
Creator: Malla, Tika Kumari
Partner: UNT Libraries

The Castle/Nikki Heat Phenomenon: A Detailed Examination of Female Representation in Entertainment Media

Description: As entertainment reflects a culture's ideology, it is important for researchers to study its messages and subsequently its potential meanings. Entertainment has the power to inform and persuade, creating models for behavior with which the public interacts. The entertainment texts for the purpose of this study are the Castle television series and the Nikki Heat novels. Together, they create a unique multi-layer fictional world. By using postmodern, feminist, communication, and entertainment theories, the results of this study provide a tightly focused lens which views a narrow aspect of entertainment media. Each text was thoroughly examined using textual analysis, Feminist Poststructuralist Discourse Analysis, and conversation analysis. Contrary to expectations, the results indicated that the Castle and Nikki Heat texts support hegemonic ideology, particularly through the use of exaggerated stereotypes, strict gender roles, imagery, and narrative choices that help perpetuate rape culture. The discussion outlines how these results can be interpreted through the dominant messages presented in the texts. This research is intended to serve as a foundation for future research regarding entertainment media.
Date: December 2016
Creator: Skinner, Katharine Virginia
Partner: UNT Libraries

Catalytic Properties and Mechanical Behavior of Metallic Glass Powders

Description: Lack of crystalline order and microstructural features such as grain/grain-boundary in metallic glasses results in a suite of remarkable attributes including very high strength, close to theoretical elasticity, high corrosion and wear resistance, and soft magnetic properties. By altering the morphology and tuning of composition, MGs may be transformed into high-performance catalytic materials. In this study, the catalytic properties of metallic glass powders were demonstrated in dissociating toxic organic chemicals such as AZO dye. BMG powders showed superior performance compared to state of the art crystalline iron because of their high catalytic activity, durability, and reusability. To enhance the catalytic properties, high energy mechanical milling was performed to increase the surface area and defect density. Iron-based bulk metallic glass (BMG) of composition Fe48Cr15Mo14Y2C15B6 was used because of its low cost and ability to make large surface area by high energy ball milling. AZO dye was degraded in less than 20 minutes for the 9 hours milled Fe-BMG. However, subsequent increase in ball milling time resulted in devitrification and loss of catalytic activity as measured using UV-Visible spectroscopy. Aluminum-based bulk metallic glass (Al-BMG) powder of composition Al82Fe3Ni8Y7 was synthesized by arc-melting the constituent elements followed by gas-atomization. The particle size and morphology were similar to Fe-BMG with a fully amorphous structure. A small percentage of transition metal constituents (Fe and Ni) in a mostly aluminum alloy showed high catalytic activity, with no toxic by-products and no change in surface characteristics. Al-alloy particles, being light-weight, were easily dispersed in aqueous medium and accelerated the redox reactions. The mechanism of dye dissociation was studied using Raman and Infrared (IR) spectroscopy. Breaking of -C-H- and - C-N- bonds of AZO dye was found to be the primary mechanism. Mechanical behavior of individual BMG particles was evaluated by in situ pico-indentation in a scanning electron ...
Date: May 2017
Creator: Garrison, Seth Thomas
Partner: UNT Libraries

Challenge the Silence

Description: This collection of personal essays about incest, abuse, and depression explores the lasting effects of an invisible childhood. The essays follow the protagonist from the age of five to her early twenties. Her brother, at a young age, becomes sexually abusive of her and her sisters, and her parents fail to protect their daughters. The family is divided as the older girls strive to defend their little sisters, while their parents attempt to excuse their son. When her brother is finally sent away, the protagonist is left to salvage what remains of her relationships with her parents.
Date: August 2012
Creator: Peterson, Erica
Partner: UNT Libraries

El Cine De Terror Español Como Espejo De La Cultura Española

Description: This study traces the history and culture of Spain as seen through the lens of the nation´s production of horror cinema. Starting from the boom of Spanish horror film in the early 1960s, the thesis compares and contrasts the political and social aspects of Spanish society throughout three distinct eras of the 20th century: 1962 – 1975 (the boom of Spanish horror film through the Franco dictatorship), 1975 – 1999 (the transition to democracy through the end of the 20th century) and 2000 – present (the 21st century). Movies as diverse as Gritos en la noche (1962, Jesús Franco), ¿Quién puede matar a un niño? (1976, Narciso Ibáñez Serrador) and Angustia (1987, Bigas Luna) are framed by culturally-related anectodes as well as correlations to their respective social environments. Special attention has been paid to the production and release of each film, especially in regards to censorship during the Franco dictatorship. The results show that Spanish horror cinema has acted as a true mirror to culture, society and politics in its native country throughout the 20th century and that this trend will likely extend in to the future.
Date: May 2014
Creator: Donahue, Tyler
Partner: UNT Libraries

Civil Liberties and National Unity: Reaction to the Sedition Act in the Southern States, 1798

Description: The traditional narrative of political party development in the United States of America during the latter half of the 1790s ascribes the decline in popularity of the Federalist Party in the Election of 1800 to that party's passage of controversial legislation, specifically the Sedition Act of 1798, prior to the election. Between the passage of the Sedition Act and the Election of 1800, however, the midterm elections of 1798-1799 transpired and resulted in a significant increase in Federalist popularity in four states – North Carolina, South Carolina, Georgia, and Virginia. This study seeks to ascertain why these four states increased their support for the Federalist Party in 1798-1799, despite the passage of the Sedition Act by the Federalist Party. By examining newspapers and election results, this study analyzes the reaction of these four states to the passage of the Sedition Act and finds that generally, these states did not react strongly against the Sedition Act in the immediate aftermath of its passage. Instead, all four states urged national unity and emphasized the need to support the national government because the United States faced the threat of war with France. This study employs a state-by-state formula to determine each state's individual reaction to the Sedition Act and the Quasi-War, finding that ultimately, the Sedition Act did not have as significant of an impact in these states as the popular narrative holds.
Date: December 2017
Creator: Robinson, Sarah Elizabeth
Partner: UNT Libraries

Clocks and Mirrors

Description: The essays featured in this collection highlight the gaps, as well as parallels, between mental illness and the human condition. In "Appearances," the narrator struggles with her own visual identity especially after reflecting on her Mom's own lengthy history with the mirror. In "Migrations," the lyrical voice of the narrator carries the reader through the typical day of a clinically depressed female character. Lastly, "Attempting the Fall," addresses the issues society has with mental illness by following the narrator from her suicide attempt to the mental ward.
Date: December 2016
Creator: Thies, Jaclyn Michele
Partner: UNT Libraries

A Comparative Analysis of Digital and Paper Restaurant Menus Based on Customer Perception and Nutritional Labeling

Description: The restaurant industry is a highly customer-driven field. Therefore, it is imperative that restaurateurs consider customer expectations with regard to restaurant menus. The purpose of this experimental study is to examine the effects of menu format (i.e., paper or digital) and amount of nutritional information (i.e., extensive, brief, or none) on customer perceptions of the effectiveness, perceived ease of use, and information quality of the menu. Furthermore, this research intends to test the effect of these three menu attributes on the outcomes of value and satisfaction in order to assess the competitive advantage of one format over the other. The Cognitive Appraisal and Information Processing Theories provide structure to the proposed conceptual framework and give credence to the findings. This study also fills gaps in the present research by not only ameliorating weaknesses of extant studies, but also by examining several different aspects of restaurant menus simultaneously within a single study.
Date: December 2016
Creator: Moody, Bailey
Partner: UNT Libraries

Competing Models of Hegemonic Masculinity in English Civil War Memoirs by Women

Description: This thesis examines the descriptions of Royalist and Parliamentarian masculinity in English Civil War memoirs by women through a close reading of three biographical memoirs written by Margaret Cavendish, duchess of Newcastle; Lady Ann Fanshawe; and Lucy Hutchinson. Descriptions of masculinity are evaluated through the lens of Raewyn Connell's theory of hegemonic masculinity to understand the impact two competing models of masculinity had on the social and political culture of the period. The prevailing Parliamentarian hegemonic masculinity in English Civil War memoirs is traced to its origins before the English Civil War to demonstrate how hegemonic masculinity changes over time. The thesis argues that these memoirs provide evidence of two competing models of Royalist and Parliamentarian masculinities during the Civil War that date back to changes in the Puritan meaning of the phrase “man of merit”, which influenced the development of a Parliamentarian model of masculinity.
Date: December 2015
Creator: Du Bon-Atmai, Evelyn
Partner: UNT Libraries

Compostable Soy-Based Polyurethane Foam with Kenaf Core Modifiers

Description: Building waste and disposable packaging are a major component in today's landfills. Most of these are structural or thermally insulative polymer foams that do not degrade over a long period of time. Currently, there is a push to replace these foams with thermoplastic or biodegradable foams that can either be recycled or composted. We propose the use of compostable soy-based polyurethane foams (PU) with kenaf core modifiers that will offer the desired properties with the ability to choose responsible end-of-life decisions. The effect of fillers is a critical parameter in investigating the thermal and mechanical properties along with its effect on biodegradability. In this work, foams with 5%, 10%, and 15% kenaf core content were created. Two manufacturing approaches were used: the free foaming used by spray techniques and the constrained expansion complementary to a mold cavity. Structure-property relations were examined using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermal conductivity, compression values, scanning electron microscopy (SEM), x-ray micro-computed tomography (micro-CT), and automated multiunit composting system (AMCS). The results show that mechanical properties are reduced with the introduction of kenaf core reinforcement while thermal conductivity and biodegradability display a noticeable improvement. This shows that in application properties can be improved while establishing a responsible end-of-life choice.
Date: August 2016
Creator: Hoyt, Zachary
Partner: UNT Libraries

A Comprehensive Modeling Framework for Airborne Mobility

Description: Mobility models serve as the foundation for evaluating and designing airborne networks. Due to the significant impact of mobility models on the network performance, mobility models for airborne networks (ANs) must realistically capture the attributes of ANs. In this paper, I develop a comprehensive modeling framework for ANs. The work I have done is concluded as the following three parts. First, I perform a comprehensive and comparative analysis of AN mobility models and evaluate the models based on several metrics: 1) networking performance, 2) ability to capture the mobility attributes of ANs, 3) randomness levels and 4) associated applications. Second, I develop two 3D mobility models and realistic boundary models. The mobility models follow physical laws behind aircraft maneuvering and therefore capture the characteristics of aircraft trajectories. Third, I suggest an estimation procedure to extract parameters in one of the models that I developed from real flight test data. The good match between the estimated trajectories and real flight trajectories also validate the suitability of the model. The mobility models and the estimation procedure lead to the creation of “realistic” simulation and evaluation environment for airborne networks.
Date: December 2013
Creator: Xie, Junfei
Partner: UNT Libraries

Control and Automation of a Heat Shrink Tubing Process

Description: Heat shrink tubing is used to insulate wire conductors, protect wires, and to create cable entry seals in wire harnessing industries. Performing this sensitive process manually is time consuming, the results are strongly dependent on the operator’s expertise, and the process presents safety concerns. Alternatively, automating the process minimizes the operators’ direct interaction, decreases the production cost over the long term, and improves quantitative and qualitative production indicators dramatically. This thesis introduces the automation of a heat shrink tubing prototype machine that benefits the wire harnessing industry. The prototype consists of an instrumented heat chamber on a linear positioning system, and is fitted with two heat guns. The chamber design allows for the directing of hot air from the heat guns onto the wire harness uniformly through radially-distributed channels. The linear positioning system is designed to move the heat chamber along the wire harness as the proper shrinkage temperature level is reached. Heat exposure time as a major factor in the heat shrink tubing process can be governed by controlling the linear speed of the heat chamber. A control unit manages the actuator position continuously by measuring the chamber’s speed and temperature. A model-based design approach is followed to design and test the controller, and MATLAB/Simulink is used as the simulation environment. A programmable logic controller is selected as the controller implementation platform. The control unit performance is examined and its responses follow the simulation results with adequate accuracy.
Date: August 2014
Creator: Yousefi Darani, Shahrokh
Partner: UNT Libraries