Engineering Commons^™

Structural, Dielectric, And Ferroelectric Characterization Of Lead-Free Calcium-Cerium Co-Doped Batio3 Ceramics, Juan Alberto Duran

Open Access Theses & Dissertations

Structure, morphology, and regulation of the dielectric properties via close-composition intervals is demonstrated for variable-cerium, constant-calcium co-doped barium titanate (Ba0.80Ca0.20CeyTi1-yO3; y=0.0-0.25; referred to BCCT). The effect of variable Ce-content on the structure and dielectric properties of BCCT is investigated. X-ray diffraction spectra confirms the studied samples are mainly in BT tetragonal phase with a small secondary phase detected as CaTiO3 in BCCT for y = 0.20 and 0.25. However, the lattice parameter reduction was evident with increasing Ce-content. Composition-driven dielectric constant leap (4,000-5,500) was observed from intrinsic BCT to BCCT for (y = 0.0-0.04). The temperature dependent dielectric constant showed …

Development And Initial Testing Of A Low-Cost, Electronic, Microprocessor-Controlled Prosthetic Knee, Lucas Jonathan Galey

Open Access Theses & Dissertations

Cost-effective lower-limb prostheses have been successful in restoring mobility, independence, and a way of life to millions of global amputees who do not have the means to afford more sophisticated prosthetics. Comprehensively, the current above knee (AK) prosthetic market is segmented into two extremes â?? very affordable relief style knees that offer basic functionality with high risk of accident due to falls, and very expensive styles that offer electronic microprocessor stumble control and adaptive cadence. There remains a gap for a middle-ground system that provides stumble control and greater stability within an achievable price bracket for the developing world. This …

Touch And Step Potential Analysis At 23.9kv To 4.16kv & 13.8kv To 4.16kv Distribution Substations With Pad-Mounted Transformers, Floating Grounds, And Other Exposed Ungrounded Metal Bodies Using Winigs, David Guillermo Guzman

Open Access Theses & Dissertations

An electrical substation is composed of various subsystems that allow for the effective and safe operation of the power grid. One of the subsystems integrating a conventional substation is defined as the ground grid system. This system allows for the effective operation of the power grid and all the electrical equipment connected to it by providing a ground potential reference, commonly known as the system ground. In addition, the ground grid system provides safety to the workers and the public transiting inside or living nearby a substation by reducing the step and touch potential (or voltage) levels present during a …

Design And Experimental Investigation Of An Oxy-Fuel Combustion System For Magnetohydrodynamic Power Extraction, Manuel Johannes Hernandez

Open Access Theses & Dissertations

A general consensus in the scientific and research community is the need to restrict carbon emissions in energy systems. Therefore, extensive research efforts are underway to develop the next generation of energy systems. In the field of power generation, researchers are actively investigating novel methods to produce electricity in a cleaner, efficient form. Recently, Oxy-Combustion for magnetohydrodynamic power extraction has generated significant interest, since the idea was proposed as a method for clean power generation in coal and natural gas power plants. Oxy-combustion technologies have been proposed to provide high enthalpy, electrically conductive flows for direct conversion of electricity. Direct …

Design And Performance Evaluations Of A Lo2/Methane Reaction Control Engine, Aaron Johnson

Open Access Theses & Dissertations

Liquid oxygen (LOX) and liquid methane (LCH4) are a propellant combination viewed as a potential enabling technology for spacecraft propulsion. Reasons why LOX/LCH4 is being used as an alternative propellant source include: it is less toxic than other propellants, it has the possibility to be harvested on extraterrestrial soil, LCH4 has a higher energy density than liquid hydrogen (LH2; commonly used on vehicle main engines), and LOX/LCH4 has comparable performance to other well-known propellant combinations. Through the continued partnership between the National Aeronautics and Space Administration (NASA) and the University of Texas at El Paso (UTEP) a LOX/LCH4 reaction control …

A Decision Making Approach For Selection Of Sustainable Pavements In Texas By Integrating Life Cycle Cost Analysis (Lcca), Life Cycle Assessment (Lca) Of Environmental And Social Impacts, Sundeep Inti

Open Access Theses & Dissertations

A sustainable pavement can be defined as the one that minimally impacts future economic opportunities, social conditions, human health, and the environment and still fulfills the engineering objectives. Although a pavement as outlined above is not yet entirely feasible, continual effort from every stakeholder with a vision of achieving sustainable development is essential for the future of society. In this study, one such effort was initiated by proposing a framework for selection of pavement design based on sustainable development.

The concept of sustainability is widely believed to be founded on three criteria: economic, environmental, and social standards. Since the purpose …

The Viability Of High-Frequency Oscillation Analysis In Eeg Signals For Seizure Prediction, Bryan David Kern

Open Access Theses & Dissertations

Seizure prediction is a decades-old research problem that has yet to reach any satisfying conclusions. Many studies have tackled the problem with varying results, but there has yet to be any major breakthroughs that define the direction of all future research. However, a promising, new predictor may have presented itself in recent years in the form of high frequency oscillations (HFOs). With the discovery of HFOs (80 - 800 Hz) as a biomarker for epilepsy, new interest has been placed in studying the high frequency content of EEGs to find a possible link between epilepsy and HFOs. In this paper, …

Modeling And Testing Of Functional Materials For Energy System Applications, Hasanul Karim

Open Access Theses & Dissertations

Energy efficiency is one of the key concerns addressing the problem of global warming. Numerous research has been going on in order to improve the efficiency of energy conversion systems to reduce the polluted emission in the atmosphere. One of the approach is monitoring and maintaining the critical parameters of operation such as temperature to ensure the desired reactions, however, the harsh environment present in these systems makes the use of current temperature sensing solutions such very challenging to implement. Wireless temperature sensors are getting increasing attention as a potential solution, however, the need of energy storage devices such as …

Structural And Dielectric Properties Of Molybdenum Doped Cobalt Ferrite, Alejandra Gabriela Melendez

Open Access Theses & Dissertations

Cobalt ferrite (CoFe2O4; referred to CFO hereafter) is one of the most promising materials from the ‘ferrites family’ with a large cubic magnetocrystalline anisotropy (1.8 – 3×10 5 Jm-3 at 300 K). CFO exhibits unique, distinct characteristics such as higher Curie temperature (~793 K), moderate saturation magnetization (80 emu/g), higher coercivity (5400 Oe), excellent chemical-structural stability, large Kerr effect, Faraday rotation and good mechanical hardness at room temperature. While it is well known that CFO is found in inverse spinel structure of the form AB2O4 , where O atoms are arranged in a face centered cubic lattice, A tetrahedral sites …

Modeling And Characterization Of Piezoelectric Based Multifunctional Structures, Ricardo Martinez Hernandez

Open Access Theses & Dissertations

Continuous monitoring of high pressure and high temperature in energy system applications has been a developing research area in today’s energy sector. Multifunctional materials have the potential to provide real-time monitoring of structures where temperature and pressure sensing is critical to its performance and efficiency. In this study, multifunctional materials are studied by embedding piezoelectric materials with two ongoing technologies, woven fabric composites and additive manufacturing (AM). The AM technology allows the flexibility of embedding a sensor within the structure, all while not compromising the mechanical performance requirements. The “smart parts” are fabricated modifying the standard additive manufacturing process, using …

Molecular Dynamics Study On Defect Reduction Strategies Towards The Fabrication Of High Performance Cd1-Xznxte/Cds Solar Cells, Jose Juan Chavez

Open Access Theses & Dissertations

Cadmium Telluride is a material widely used in terrestrial thin film photovoltaic applications due to its nearly ideal band gap (~1.5 eV) and high absorption coefficient. Due to its low manufacturing cost, this technology has the potential to become a significant energy resource if higher energy conversion efficiencies are achieved. However, the module efficiencies (~14%) are still far from the theoretical maximum (~30%) for this material in a single junction configuration. The reason behind this low performance is attributed to the high number of defects that are present within the device materials. The physics behind the formation mechanisms of these …

Modeling And Preliminary Characterization Of Passive, Wireless Temperature Sensors For Harsh Environment Applications Based On Periodic Structures, Diego Ivan Delfin Manriquez

Open Access Theses & Dissertations

Wireless temperature sensing has attained significant attention in recent years due to the increasing need to develop reliable and affordable sensing solutions for energy conversion systems and other harsh environment applications. The development of next generation sensors for energy production processing parameters, such as temperature and pressure, can result in better performance of the system. Particularly, continuous temperature monitoring in energy conversion systems can result in enhancements such as better system integrity, less pollution and higher thermal efficiencies. However, the conditions experienced in these system components hinder the performance of current solutions due to the presence of semi-conductor materials and …

Optimization Of Green Logistics Using Genetic Algorithm Approach, Gabriela Ituarte-Villarreal

Open Access Theses & Dissertations

Green Logistics (GL) becomes critical in Supply Chain Management (SCM) due to it having less of an impact to the environment. Green Logistics optimization refers to the determination depot quantity, decreasing uncovered demand and CO2 emission reduction. To date, application of Genetic Algorithm (GA) has been proven to be very efficient and reliable in solving optimization problems; it is also capable of operating simultaneously with multiple solutions. Basically, GA imitates the natural evolution of a population with initial solutions. In this Thesis a modified Genetic Algorithm is proposed to solve the multiple objective GL optimization problem. MATLAB software is used …

Simulation Of Infiltrating Rate Driven By Surface Tension-Viscosity Of Liquid Elements From The Titanium Group Into A Packed Bed, Arturo Medina

Open Access Theses & Dissertations

The simulation of infusion of molten reactive metals (e.g., yttrium) into a porous, carbide packed bed to create carbide and boride composites was studied at ultrahigh temperatures (>1700°C). The infusion was investigated through a computational fluid dynamic (CFD) system of capillary pores and compared to a predicted analytical calculation formulated by Selmak and Rhines. Simulations of two-phase flow penetration of yttrium into a packed bed of B4C were investigated and compared with titanium, zirconium, hafnium, and samarium liquids. The non-reactive, liquid metal infusion was primarily driven by the surface tension and viscosity. The liquid metal depth and rate of …

Sustainable River-Basin Salinity Management: Treatment Of Natural Brine Springs For Recovery Of Purified Sodium Chloride And Other Valuable Minerals, Priscilla L. Sandoval

Open Access Theses & Dissertations

A treatment process was developed to extract sodium chloride salt, via evaporation, from high-salinity natural brine springs. The source of the brine studied in this project is watershed of the Salt Fork of the Brazos River in Texas. When evaporation is applied to the brine, various impurities precipitate along with the sodium chloride salt (halite). Therefore, a treatment was developed in order to produce a valuable, high-purity salt product. The treatment consists of pretreating the brine with sodium carbonate and hydrochloric acid to for softening and decarbonation. After evaporation, a brine wash post-treatment process was employed to increase the purity …

Hybrid Nano-Structure For Enhanced Energy Storage Devices, Mohammad Arif Ishtiaque Shuvo

Open Access Theses & Dissertations

The goal of this research is to develop electrode materials using various nano-structure hybrids for improved energy storage devices. Enhancing the performance of energy storage device has been gaining tremendous attention since it holds the key solution to advance renewable energy usage thus reduce the consumption of fossil fuels. The application of energy storage devices such as super-capacitor and Li-ion-battery has seen significant growth; however, it is still limited mainly by charge/discharge rate and energy density. One of the solutions is to use nano-structure materials, which offer higher power at high energy density and improved stability during the charge discharge …

Design And Testing Of An Ox/Ch4 Swirl Torch Ignition System, Gabriel Ricardo Trujillo

Open Access Theses & Dissertations

NASA has renewed its interest in oxygen and methane as propellants for propulsion. Some of the reasons that drive this interest are the ease of storage of liquid methane when compared to hydrogen, the handling safety when compared to hypergols, in-situ resource utilization and its relative clean burning process. This project is part of the larger goal of the Center for Space Exploration Technology Research (cSETR) to better understand the aspects of using this propellants to create future hardware that are specifically optimized for their use. This paper discusses the testing of a previous iteration of the swirl torch igniter …

Multi-3d System: Advanced Manufacturing Through The Implementation Of Material Handling Robotics, Jose Luis Coronel Jr.

Open Access Theses & Dissertations

Since the rise of additive manufacturing (AM), innovation has been at the forefront. Additive Manufacturing systems that incorporate complex processes are steadily being developed. One example is the Multi3D System, which was designed to integrate the ability to print multi-material parts with that of embedding electronics. To achieve this automated process, the Multi3D incorporates a six-axis robotic arm to transfer a build platform containing a printed part, to various manufacturing stations (two fused deposition modeling (Stratasys, FDM400mc) systems and a computer numerical control router (Techno CNC Router). The robot is a Yaskawa Motoman MH50 chosen for its payload capacity of …

Process Monitoring In Additive Manufacturing Aimed Toward Part Qualification, Shakerur Ridwan

Open Access Theses & Dissertations

Additive Manufacturing (AM), or layer-by-layer part fabrication, has played a tremendous role in the maker culture by allowing ideas to be materialized with limited resources or knowledge in manufacturing. Various cutting edge AM technologies exist today that are used to create end-use parts; however, these technologies are still new and the processes have not gone through the rigorous evaluation process that traditional manufacturing (i.e. milling, stamping, casting) methods have been through. As a result, several important questions arise when looking to adapt AM technology, including control of the manufacturing process, effect of manufacturing process on part properties, level of variance …

Predicting Irrigation Efficiency In The Rio Grande Project, Gerardo Melendez

Open Access Theses & Dissertations

Surface water losses in the Bureau of Reclamation’s (USBR) Rio Grande Project have become more prevalent within the past few years of the drought of the 2000’s. Simple regressions were performed in order to find correlations and determine factors that may affect the flows within the Rio Grande Project. Correlations were found in the difference between Rio Grande below Caballo flows and Rio Grande at El Paso flows, and between the diversion ratio and groundwater levels. Caballo Reservoir release amounts were found to be fairly well correlated with the difference between the Rio Grande below Caballo and the Rio Grande …

Alternative Fatigue Cracking Resistance Assessment Criteria Of Asphalt Mixtures With Overlay Tester, Alejandro Miramontes

Open Access Theses & Dissertations

The accumulation of damage due to cracking of hot mix asphalt (HMA) layers under repeated loading along with the climatic effects is known as fatigue cracking. The Overlay Tester (OT) has been implemented or considered by several highway agencies as an index to evaluate the cracking susceptibility and resistance to cracking of asphalt mixtures in the laboratory. The performance indicator used to measure the quality of the HMA mixes is the number of cycles that a specimen may resist during the test until the crack appears and fully propagates to the top of the specimen. The repeatability of the number …

Mechanical And Optical Characterization Of Tungsten Oxynitride (W-O-N) Nano-Coatings, Oscar Roberto Nunez

Open Access Theses & Dissertations

Aation and cation doping of transition metal oxides has recently gained attention as a viable option to design materials for application in solar energy conversion, photo-catalysis, transparent electrodes, photo-electrochemical cells, electrochromics and flat panel displays in optoelectronics. Specifically, nitrogen doped tungsten oxide (WO3) has gained much attention for its ability to facilitate optical property tuning while also demonstrating enhanced photo-catalytic and photochemical properties. The effect of nitrogen chemistry and mechanics on the optical and mechanical properties of tungsten oxynitride (W-O-N) nano-coatings is studied in detail in this work. The W-O-N coatings were deposited by direct current (DC) sputtering to a …

Design Optimization And Optical Characterization Of A High Temperature Solar Receiver, Samia Afrin

Open Access Theses & Dissertations

Concentrated solar power (CSP) is a fast forwarding technology in power generation sector because of its' competitive price, abundance in nature and the most important fact is its' energy storage capability. Among the four types of available CSP technology, central receiver has more potential concerning with high temperature, power block efficiency and levelized cost of energy (LCOE). Other than conventional type of receiver design, the concept of this work is very particular in a sense of its design novelty.

National Renewable Energy Laboratory (NREL) come up with a new concept of high temperature solar receiver called near black body (NBB) …

Processing And Property Evaluation Of Tungsten-Based Mixed Oxides For Photovoltaics And Optoelectronics, Mirella Vargas

Open Access Theses & Dissertations

Tungsten Oxide (WO3) films and low-dimensional structures have proven to be promising candidates in the fields of photonics and electronics. WO3 is a well-established n-type semiconductor characterized by unique electrochromic behavior, an ideal optical band gap that permits transparency over a wide spectral range, and high chemical integrity. The plethora of diverse properties endow WO3 to be highly effective in applications related to electrochromism, gas sensing, and deriving economical energy. Compared to the bulk films, a materials system involving WO3 and a related species (elements or metal oxides) offer the opportunity to tailor the electrochromic response, and an overall enhancement …

Salt And Mineral Recovery From High Salinity Waters, Osvaldo Alejandro Broesicke

Open Access Theses & Dissertations

Natural salt springs in the Salt Fork Basin in Crosby County, Texas, result in the natural salt pollution of the Brazos River, rendering it unusable for most potable purposes. Previous research indicates that by intercepting the source of the pollution, water quality of the Brazos River can be greatly improved. This paper investigates and assesses two strategies for salt and mineral recovery using natural brine collected from the Salt Fork Basin, the first of which is presented in a separate work.

The research described in this paper evaluates the potential of a desulfation, soda-caustic softening, acidification/decarbonation, and evaporation process to …

Characterization Of Kendex® 0834 (Heavy Resins) & Kendex® 0897 (Light Resins), Victor Correa

Open Access Theses & Dissertations

Characterization of crude oil and some of its refined products has always been a challenge in the refining industry. This is mainly due to the high molecular complexity of crude oil. In this research, Heavy and Light Resins extracted from Penn Grade crude oil were analyzed with a wide variety of techniques, ranging from X-Ray Diffraction, Electron Microscopy, Fourier Transformed Infrared, C-13 Nuclear Magnetic Resonance, and chromatographic methods. An asphaltene extraction protocol was performed on both products. Only the Heavy Resin sample yielded a low amount of asphaltene. Results show that both Resins have a high degree of carbon branching, …

Moisture Susceptibility Of Dense Graded Asphalt Concrete Using Cyclic Moistue Induced Stress Tester, Sarvesh Dip Dhakal

Open Access Theses & Dissertations

Moisture damage in asphalt concrete causes loss in mechanical properties of asphalt material due to the presence of moisture in its microstructures in a liquid or a vapor state. Some of the common types of distress observed in asphalt pavements due to moisture damage are stripping (separation of asphalt binder and aggregate), raveling (dislodgement of aggregate particles in asphalt mixture from surface), and hydraulic scour (a process that occurs on a saturated surface by which the pavement material is eroded due to dynamic action of tires in the presence of water). This Thesis focuses on the research on the effects …

Simulations Of The Effects Of Temperature And Plasma In Carbide Processing, Alejandro Garcia

Open Access Theses & Dissertations

The transient surface temperature of particles within a packed bed was simulated to enable ultimately the prediction of plasma-surface reactions at ultrahigh temperatures. The motivation for the present study was along two fronts - the reactive infusion of liquid alloys at ultrahigh temperatures to process metal matrix or ceramic matrix composites and the plasma processing of materials to spike the surface temperatures to enable the formation of protective oxidizing scales on ultrahigh ceramic composites. The transient temperature simulations determined that a graphite crucible containing B4C spherical particles heated from 298 to 2128 K and 2504 K occurred in about 900 …

Comparison Of Bicycle Transportation Systems In El Paso And Prague, Jose C Hernandez

Open Access Theses & Dissertations

Bicycle transportation infrastructure has an important role in bicycle transportation mode. Every year there are hundreds of accidents where bicyclist are involve, because there is not a good infrastructure for bicycles in the roads bicyclists have a potential risk. One of the main purposes is maintain the bicyclistsâ?? safety in the roads to attract more people to use this eco-friendly transportation mode. The goal of this Thesis is compare the bicycle infrastructure in two different countries, United States and Czech Republic. The history and the main terminology are described in firsts chapters. Based on law and regulations, design criteria and …

Synchronization Of Bistatic Radar Using Chaotic Amplitude And Frequency Modulated Signals, Chandra Sekhar Pappu

Open Access Theses & Dissertations

The purpose of this work is to develop a synchronization scheme for bistatic radar that uses a 3-D chaotic system to generate and process wideband AM and FM signals, which allows for the extraction of high range-resolution information from targets. For AM bistatic radar, the setup includes a drive oscillator at the transmitter and a response oscillator at the receiver. The challenge is synchronizing the response oscillator to the drive oscillator with a scaled version of the transmitted signal sr(t, x) = αs t(t, x), where x is a chaotic state variable and α is a scaling factor. Here, α …