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 Degree Level: Master's
 Collection: UNT Theses and Dissertations
Accelerated Corrosion Test with Operation Simulation of All-Aluminum Microchannel Heat Exchangers

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

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Date: 2016-5
Creator: Vaughan, Haydn
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 ...
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Addressing Social Elements of Wildfire: Risk, Response, and Recovery in Highland Village, TX

Addressing Social Elements of Wildfire: Risk, Response, and Recovery in Highland Village, TX

Date: 2016-5
Creator: MacKinnon, Jessica
Description: Representatives of the City of Highland Village expressed concern over the risk of wildfires for their community. Anthropology provides many tools for and examples of disaster assessment of preparedness, response, recovery, and mitigation. These tools combined with Geographic Information Systems (GIS) can provide a holistic, cultural ecological look at how such a disaster may take place in the city. The project's methods included a detailed survey of preparedness steps which was analyzed using SPSS and also imported into ArcGIS for spatial analysis, and semi-formal, in-depth interviews with residents of the community regarding preparedness, response, and recovery. Residents fell into a middle category of preparedness, with the majority of participants considering or implementing a few recommended preparedness steps. Interview participants expressed respect for and trust of the city and first-responders, as well as a willingness to volunteer their help during response and recovery stages. Finally the American Community Survey showed that resident socioeconomic vulnerability was considerably low, and no action needed to be taken to advocate for at-risk individuals. Overall, the City of Highland Village showed a high resiliency to disaster. A wildfire likely will not have a major impact on the community as a whole, though the city may reduce ...
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Adhesion and Surface Energy Profiles of Large-area Atomic Layers of Two-dimensional MoS2 on Rigid Substrates by Facile Methods

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

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Date: 2016-5
Creator: Wu, Min
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 ...
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AirSniffer: A Smartphone-Based Sensor Module for Personal Micro-Climate Monitoring

AirSniffer: A Smartphone-Based Sensor Module for Personal Micro-Climate Monitoring

Date: 2016-5
Creator: Smith, Jeffrey Paul
Description: Environmental factors can have a significant impact on an individual's health and well-being, and a primary characteristic of environments is air quality. Air sensing equipment is available to the public, but it is often expensive,stationary, or unusable for persons without technical expertise. The goal of this project is to develop an inexpensive and portable sensor module for public use. The system is capable of measuring temperature in Celsius and Fahrenheit, heat index, relative humidity, and carbon dioxide concentration. The sensor module, referred to as the "sniffer," consists of a printed circuit board that interconnects a carbon dioxide sensor, a temperature/humidity sensor, an Arduino microcontroller, and a Bluetooth module. The sniffer is small enough to be worn as a pendant or a belt attachment, and it is rugged enough to consistently collect and transmit data to a user's smartphone throughout their workday. The accompanying smartphone app uses Bluetooth and GPS hardware to collect data and affix samples with a time stamp and GPS coordinates. The accumulated sensor data is saved to a file on the user's phone, which is then examined on a standard computer.
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A Behaviorally Planned Community of Practice: A Description and Evaluation of one Area of Staff Development

A Behaviorally Planned Community of Practice: A Description and Evaluation of one Area of Staff Development

Date: 2016-5
Creator: Ferguson, Julia L
Description: Staff training packages combining instructions, modeling, practice, and feedback have been shown to be effective in demonstrating skills to work in early intensive behavioral intervention, but maintenance and generalization of the skills trained are often not addressed. Establishing a community of practice, in which staff members continue to learn and develop new skill sets from one another through shared experiences and information, may lead to the endurance and maintenance of desired staff behavior over time. The purpose of the current study is to evaluate the effects of a behaviorally designed community of practice on staff use of socially embedded consequences. The effects of the training procedure were evaluated using a concurrent multiple baseline design across two sites (7 staff members). The results suggest that the behaviorally planned community of practice was effective in reinforcing and maintaining staff use of socially embedded consequences for at least 5 to 9 weeks. Additionally, the number of learning opportunities provided by the staff and social engagement between staff and child increased.
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Biodiversity and Genetic Structure of Benthic Macroinvertebrates along an Altitudinal Gradient: A Comparison of the Windhond and Róbalo River Communities on Navarino Island, Chile

Biodiversity and Genetic Structure of Benthic Macroinvertebrates along an Altitudinal Gradient: A Comparison of the Windhond and Róbalo River Communities on Navarino Island, Chile

Date: 2016-5
Creator: Pulliam, Lauren
Description: Altitudinal gradients in Sub-Antarctic freshwater systems present unique opportunities to study the effect of distinct environmental gradients on benthic macroinvertebrate community composition and dispersal. This study investigates patterns in biodiversity, dispersal and population genetic structure of benthic macroinvertebrate fauna across an altitudinal gradient between two watersheds on Navarino Island in southern Chile. Patterns in diversity, density, evenness and functional feeding groups were not significantly different across the altitudinal gradient in both the Windhond and Róbalo Rivers. Taxa richness in both rivers generally increased from the headwaters of the river to the mouth, and functional feeding group patterns were consistent with the predictions of the River Continuum Concept. Population genetic structure and gene flow was investigated by sampling the mitochondrial cytochrome oxidase I gene in two invertebrate species with different dispersal strategies. Hyalella simplex (Amphipoda) is an obligate aquatic species, and Meridialaris chiloeense (Ephemeroptera) is an aquatic larvae and a terrestrial winged adult. Contrasting patterns of population genetic structure were observed. Results for Hyalella simplex indicate significant differentiation in genetic structure in the Amphipod populations between watersheds and lower genetic diversity in the Róbalo River samples, which may be a result of instream dispersal barriers. Meridialaris chiloeense exhibited weak population structure ...
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Bioinspired and biocompatible coatings of poly(butylene adipate-co-terephthalate) and layer double hydroxide composites for corrosion resistance

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

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Date: 2016-5
Creator: Rizvi, Syed Hussain
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.
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Caffeine’s effects on pausing during alternating work requirements.

Caffeine’s effects on pausing during alternating work requirements.

Date: 2016-5
Creator: Libman, Benjamin M.
Description: There is a significant body of literature stating that caffeine is the most widely consumed drug in the world, yet its effects on operant behavior are little understood. Some of the current research on caffeine suggests that it may play a role in altering motivational states related to transitions between previous and upcoming work requirements. The purpose of the current study was to examine the effects of caffeine on postreinforcement pausing during transitions between small and large fixed ratio rudiments. Eight rats were exposed to five doses of caffeine and and a two-component multiple schedule. We found that caffeine does systematically alter the length of pausing during transitions between fixed ratio requirements, however the magnitude of the effect may be dependent on the baseline rate of responding.
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Carnaval, grotesco y dialogismo en las zarzuelas de Pablo Sorozábal

Carnaval, grotesco y dialogismo en las zarzuelas de Pablo Sorozábal

Date: 2016-5
Creator: Murphy, Deirdre
Description: In the present study, the three principal theories of Russian theorist Mikhail Bakhtin--the carnavalesque, grotesque, and dialogical--are applied to the musical-theatre genre of the Spanish zarzuela. The focus of the study centers on the works of composer Pablo Sorozábal and the various librettists who collaborated with him, among them the renowned literary author Pío Baroja. Within this study, zarzuela is first analyzed on its own in terms of the academic debate surrounding the genre and its importance in terms of both literary and musical criticism. After establishing the particular capacity of the zarzuela to make important cultural contributions, the central theoretical framework of the thesis is established via Bakhtinian theory, and several links are drawn between this theory and the genre of the zarzuela, which is shown to be a body of work often capable of conveying subversive messages, both cultural and sociopolitical. With this critical lens, then, the specific sociopolitical context of Spain between 1931-1942 is analyzed and described in order to illustrate the various extratextual and intertextual elements at play in Sorozábal's zarzuelas. The three works ultimately studied are Katiuska (1931), Adiós a la bohemia (1933), and Black, el payaso (1942). By way of highlighting the Bakhtinian characteristics ...
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Causes of the Jewish Diaspora Revolt in Alexandria: Regional Uprisings from the Margins of Greco-Roman Society

Causes of the Jewish Diaspora Revolt in Alexandria: Regional Uprisings from the Margins of Greco-Roman Society

Date: 2016-5
Creator: Vargas, Miguel M
Description: This thesis examines the progression from relatively peaceful relations between Alexandrians and Jews under the Ptolemies to the Diaspora Revolt under the Romans. A close analysis of the literature evidences that the transition from Ptolemaic to Roman Alexandria had critical effects on Jewish status in the Diaspora. One of the most far reaching consequences of the shift from the Ptolemies to Romans was forcing the Alexandrians to participate in the struggle for imperial patronage. Alexandrian involvement introduced a new element to the ongoing conflict among Egypt’s Jews and native Egyptians. The Alexandrian citizens consciously cut back privileges the Jews previously enjoyed under the Ptolemies and sought to block the Jews from advancing within the Roman system. Soon the Jews were confronted with rhetoric slandering their civility and culture. Faced with a choice, many Jews forsook Judaism and their traditions for more upwardly mobile life. After the outbreak of the First Jewish War Jewish life took a turn for the worse. Many Jews found themselves in a system that classified them according to their heritage and ancestry, limiting advancement even for apostates. With the resulting Jewish tax (fiscus Judaicus) Jews were becoming more economically and socially marginalized. The Alexandrian Jews were ...
Contributing Partner: UNT Libraries
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