UNT Libraries - 77 Matching Results

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open access

Analysis of Heat Transfer Enhancement in Channel Flow through Flow-Induced Vibration

Description: In this research, an elastic cylinder that utilized vortex-induced vibration (VIV) was applied to improve convective heat transfer rates by disrupting the thermal boundary layer. Rigid and elastic cylinders were placed across a fluid channel. Vortex shedding around the cylinder led to the periodic vibration of the cylinder. As a result, the flow-structure interaction (FSI) increased the disruption of the thermal boundary layer, and therefore, improved the mixing process at the boundary. This … more
Date: December 2017
Creator: Kota, Siva Kumar k
Item Type: Refine your search to only Thesis or Dissertation
open access

Estimation of Aircraft Emissions for the Corpus Christi International Airport, Corpus Christi, Texas

Description: Commercial aviation is a vital part of the United States economy. It generates over $1 trillion annually, which is more than 5% of the U.S. GDP, and produces approximately 10 million jobs. Every year there is an increase in commercial air traffic. This is attributed to expanding trade between states and other countries, which requires larger amounts of cargo aircraft in operation, and also catering to the growing number of middle and upper class passengers who travel for business and pleasure p… more
Date: May 2013
Creator: Thomas, Gregson Johann
Item Type: Refine your search to only Thesis or Dissertation
open access

Using a Multimodal Sensing Approach to Characterize Human Responses to Affective and Deceptive States

Description: Different ways to measure human affective and deceptive reactions to stimulus have been developed. One method is a multimodal approach using web camera, thermal imaging camera and physiological sensors data to extract different features in the human face (verbal and non-verbal behavior) such as breathing rate, heart rate, face temperature, skin conductance, eye tracking, language analysis and facial expressions among others. Human subjects from different ages and ethnicity were exposed to two d… more
Date: May 2013
Creator: Narvaez-Valle, Alexis
Item Type: Refine your search to only Thesis or Dissertation
open access

Optical Transparent Pmma Composite Reinforced By Coaxial Electrospun Pan Hollow Nanofibers

Description: Electrospinning has been recognized as an efficient technique for the fabrication of polymer fibers. These electrospun fibers have many applications across a broad range of industries. In this research, optical transparent composites were successfully fabricated by embedding polyacrylonitrile (PAN) hollow nanofibers into poly (methyl methacrylate) (PMMA) matrix. The hollow PAN nanofibers were prepared by coaxial electrospinning. The PAN was used as the shell solution, and the mineral oil was us… more
Date: May 2013
Creator: Antoine, Donley
Item Type: Refine your search to only Thesis or Dissertation
open access

Thermal Characterization of Austenite Stainless Steel (304) and Cnt Films of Varying Thickness Using Micropipette Thermal Sensors

Description: Thermal transport behavior of austenite stainless steel stripe (304) and the carbon nano-tubes (CNTs) films of varying thickness are studied using a micropipette thermal sensor. Micropipette sensors of various tip sizes were fabricated and tested for the sensitivity and reliability. The sensitivity deviated by 0.11 for a batch of pipette coated under same physical vapor deposition (PVD) setting without being affected by a tip size. Annealing, rubber coating and the vertical landing test of the … more
Date: May 2013
Creator: Dangol, Ashesh
Item Type: Refine your search to only Thesis or Dissertation
open access

Ultrafast Laser Sampling of a Plant Tissue and ion Conductivity Measurement for Investigation of Light Stress Generation Mechanisms

Description: In this study we applied ultra-short laser pulses on a biological sample (Arabidopsis), in order to cut it precisely in a square pattern and subsequently use it for studying stress generation mechanisms. For this purpose, we utilized femtosecond laser pulses at 100 fs pulse width and 80 MHz repetition rate. We took two processing parameters into consideration such as laser power, laser exposure time which is related to the stage speed. Therefore, we were able to find the laser optimum condition… more
Date: August 2010
Creator: Abtahi, Seyed Ali
Item Type: Refine your search to only Thesis or Dissertation
open access

Multi-year Operation Effect of Geothermal Heat Exchanger on Soil Temperature for Unt Zero Energy Lab

Description: Ground source heat pump (GSHP) uses earth’s heat to heat or cool space. Absorbing heat from earth or rejecting heat to the earth, changes soil’s constant temperature over the multiple years. In this report we have studied about Soil temperature change over multiple years due to Ground loop heat exchanger (GLHE) for Zero Energy Research Laboratory (ZØE) which is located in Discovery Park, University of North Texas, Denton, TX. We did 2D thermal analysis GLHP at particular Depth. For simulation w… more
Date: December 2013
Creator: Walikar, Vinayak P.
Item Type: Refine your search to only Thesis or Dissertation
open access

Using a Multimodal Sensing Approach to Characterize Human Thermal Comfort Level

Description: A method to distinguish human level of comfort has been developed by using a thermal camera, physiological sensors, and a surroundings sensor. The method has successfully collected data from hominal facial features, breathing rate, skin temperature, room temperature, blood volume pressure, relative humidity, and air velocity. Participants from all genders and races were involved in two sessions of a human comfort experiment including a psychology survey session. The variables, such as room temp… more
Date: December 2013
Creator: Wicaksono, Cakra Aditya
Item Type: Refine your search to only Thesis or Dissertation
open access

Characterization of Viscoelastic Properties of a Material Used for an Additive Manufacturing Method

Description: Recent development of additive manufacturing technologies has led to lack of information on the base materials being used. A need arises to know the mechanical behaviors of these base materials so that it can be linked with macroscopic mechanical behaviors of 3D network structures manufactured from the 3D printer. The main objectives of my research are to characterize properties of a material for an additive manufacturing method (commonly referred to as 3D printing). Also, to model viscoelasti… more
Date: December 2013
Creator: Iqbal, Shaheer
Item Type: Refine your search to only Thesis or Dissertation
open access

Thermally Stimulated Depolarization Current Evaluation of Molding Compounds

Description: TSDC (thermally stimulated depolarization current) is one of the most important and popular technique for investigating electret materials. TSDC technique can indicate the magnitude of polarization and depolarization, relaxation time, charge-storage, glass transition, and activation energy. To fully investigate polarization and relaxation for pure epoxy and filled epoxy materials, a TSDC system was built and verified by the research. The article describes the building processes and verification… more
Date: May 2014
Creator: Zhao, Shunli
Item Type: Refine your search to only Thesis or Dissertation
open access

Source Apportionment Analysis of Measured Volatile Organic Compounds in Corpus Christi, Texas

Description: Corpus Christi among of the largest industrialized coastal urban areas in Texas. The strategic location of the city along the Gulf of Mexico allows for many important industries and an international business to be located. The cluster of industries and businesses in the region contribute to the air pollution from emissions that are harmful to the environment and to the people living in and visiting the area. Volatile organic compounds (VOC) constitute an important class of pollutants measured i… more
Date: May 2014
Creator: Abood, Ahmed T.
Item Type: Refine your search to only Thesis or Dissertation
open access

The Study of Comprehensive Reinforcement Mechanism of Hexagonal Boron Nitride on Concrete

Description: The addition of hexagonal boron nitride (h-BN) has introduced a comprehensive reinforcing effect to the mechanical and electrochemical properties of commercial concrete, including fiber reinforced concrete (FRC) and steel fiber reinforced concrete (SFRC). Although this has been proven effective and applicable, further investigation and study is still required to optimize the strengthen result which will involve the exfoliation of h-BN into single-layered nano sheet, improving the degree of disp… more
Date: August 2015
Creator: He, Qinyue
Item Type: Refine your search to only Thesis or Dissertation
open access

Highly Stretchable Miniature Strain Sensor for Large Dynamic Strain Measurement

Description: This thesis aims to develop a new type of highly stretchable strain sensor to measure large deformation of a specimen subjected to dynamic loading. The sensor was based on the piezo-resistive response of carbon nanotube(CNT)/polydimethysiloxane (PDMS) composites thin films, some nickel particles were added into the sensor composite to improve the sensor performance. The piezo-resistive response of CNT composite gives high frequency response in strain measurement, while the ultra-soft PDMS matri… more
Date: May 2016
Creator: Yao, Shulong
Item Type: Refine your search to only Thesis or Dissertation
open access

Biomass-Derived Activated Carbon Through Self-Activation Process

Description: Self-activation is a process that takes advantage of the gases emitted from the pyrolysis process of biomass to activate the converted carbon. The pyrolytic gases from the biomass contain CO2 and H2O, which can be used as activating agents. As two common methods, both of physical activation using CO2 and chemical activation using ZnCl2 introduce additional gas (CO2) or chemical (ZnCl2), in which the CO2 emission from the activation process or the zinc compound removal by acid from the follow-up… more
Date: May 2016
Creator: Xia, Changlei
Item Type: Refine your search to only Thesis or Dissertation
open access

A study of the impact of unconventional sources within a large urban area: evidence from spatio-temporal assessment of volatile organic compounds.

Description: Conventional sources of emissions have been a prime target for policymakers in designing pollution control strategies. However, the evolution of shale gas activities is a growing concern over the impact of unconventional sources on urban and regional air quality. Owing to the development of Barnett Shale production, the fast-growing Dallas-Fort Worth (DFW) metroplex has encountered both types of these emissions. Oil and gas activities result in emissions of ozone precursors, notably volatile or… more
Date: May 2016
Creator: Matin, Maleeha
Item Type: Refine your search to only Thesis or Dissertation
open access

Bioinspired & 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… more
Date: May 2016
Creator: Rizvi, Hussain R.
Item Type: Refine your search to only Thesis or Dissertation
open access

Investigation of the Effect of Particle Size and Particle Loading on Thermal Conductivity and Dielectric Strength of Thermoset Polymers

Description: Semiconductor die attach materials for high voltage, high reliability analog devices require high thermal conductivity and retention of dielectric strength. A comparative study of effective thermal conductivity and dielectric strength of selected thermoset/ceramic composites was conducted to determine the effect of ceramic particle size and ceramic particle loading on thermoset polymers. The polymer chosen for this study is bismaleimide, a common aerospace material chosen for its strength and t… more
Date: May 2016
Creator: Warner, Nathaniel A.
Item Type: Refine your search to only Thesis or Dissertation
open access

Ozone Pollution of Shale Gas Activities in North Texas

Description: The effect of shale gas activities on ground-level ozone pollution in the Dallas-Fort Worth area is studied in detail here. Ozone is a highly reactive species with harmful effects on human and environment. Shale gas development, or fracking, involves activities such as hydraulic fracturing, drilling, fluid mixing, and trucks idling that are sources of nitrogen oxides (NOX) and volatile organic compounds (VOC), two of the most important precursors of ozone. In this study two independent approach… more
Date: May 2016
Creator: Ahmadi, Mahdi
Item Type: Refine your search to only Thesis or Dissertation
open access

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 M… more
Date: May 2016
Creator: Wu, Min
Item Type: Refine your search to only Thesis or Dissertation
open access

Feasibility of a New Technique to Determine Dynamic Tensile Behavior of Brittle Materials

Description: Dynamic tensile characterization of geo-materials is critical to the modeling and design of protective structures that are often made of concrete. One of the most commonly used techniques currently associated with this type of testing is performed with a Kolsky bar and is known as the spall technique. The validity of the data from the spall technique is highly debated because the necessary boundary conditions for the experiment are not satisfied. By using a technique called pulse shaping, a new… more
Date: May 2016
Creator: Dean, Andrew W.
Item Type: Refine your search to only Thesis or Dissertation
open access

Field Validation of Zero Energy Lab Water-to-Water Ground Coupled Heat Pump Model

Description: Heat pumps are a vital part of each building for their role in keeping the space conditioned for the occupant. This study focuses on developing a model for the ground-source heat pump at the Zero Energy lab at the University of North Texas, and finding the minimum data required for generating the model. The literature includes many models with different approaches to determine the performance of the heat pump. Each method has its pros and cons. In this research the equation-fit method was used … more
Date: May 2016
Creator: Abdulameer, Saif
Item Type: Refine your search to only Thesis or Dissertation
open access

Conceptual Framework for the Development of an Air Quality Monitoring Station in Denton, Texas

Description: Denton, Texas consistently reaches ozone nonattainment levels. This has led to a large focus of air pollution monitoring efforts in the region, with long-range transport being explored as a key contributor. For this study, the University of North Texas Discovery Park campus was chosen as a prospective location for an extensive air quality monitoring station. Sixteen years of ozone and meteorological data for five state-run monitoring sites within a 25 mile radius, including the nearest Denton A… more
Date: August 2016
Creator: Boling, Robyn
Item Type: Refine your search to only Thesis or Dissertation
open access

Feasibility Study of Consolidation by Direct Compaction and Friction Stir Processing of Commercially Pure Titanium Powder

Description: Commercially pure titanium can take up to six months to successfully manufacture a six-inch in diameter ingot in which can be shipped to be melted and shaped into other useful components. The applications to the corrosion-resistant, light weight, strong metal are endless, yet so is the manufacturing processing time. At a cost of around $80 per pound of certain grades of titanium powder, the everyday consumer cannot afford to use titanium in the many ways it is beneficial simply because the numb… more
Date: August 2016
Creator: Nichols, Leannah Marie
Item Type: Refine your search to only Thesis or Dissertation
open access

Dissimilar Friction Stir Welding Between Magnesium and Aluminum Alloys

Description: Joining two dissimilar metals, specifically Mg and Al alloys, using conventional welding techniques is extraordinarily challenging. Even when these alloys are able to be joined, the weld is littered with defects such as cracks, cavities, and wormholes. The focus of this project was to use friction stir welding to create a defect-free joint between Al 2139 and Mg WE43. The stir tool used in this project, made of H13 tool steel, is of fixed design. The design included an 11 mm scrolled and concav… more
Date: December 2016
Creator: Reese, Gregory A
Item Type: Refine your search to only Thesis or Dissertation
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