Engineering Commons^™

Enhancing Surface Finish Of Fused Deposition Modeling Parts Through Targeted Chemicals And Design Of Experiments, Saurabh Nayyar Nayyar

Open Access Theses & Dissertations

Fused Deposition Modeling (FDM) is one of the most popular rapid prototyping (RP) technologies due to its low operational cost, high fabrication speed, and range of applications served. However, FDM fabricated parts generally have poor surface finish quality which have limited their utilization in end-use applications. To enhance surface quality of FDM materials, several researchers have regulated key process parameters using the FDM material, Acrylonitrile Butadiene Styrene (ABS), with varying results. The main goal of this research is to investigate the effects of a post-fabrication chemical treatment process on the surface roughness for FDM parts of the FDM material ULTEM. …

Analysis Of Nitrogen Speciation And Removal In Direct Potable Reuse In El Paso, Texas, Oluwaseye Michael Owoseni

Open Access Theses & Dissertations

Population growth and increasing demand for potable water is causing a need for additional sources to water portfolios in areas with water scarcity. Direct Potable Reuse (DPR) is gaining recognition in these regions and ensuring appropriate measures for the removal of nitrogen and other contaminants cannot be overemphasized. Two nitrogen species, nitrate and nitrite are known to cause harmful effects on young infants below the age of six months. El Paso Water Utilities conducted a pilot test for DPR to ascertain the viability of DPR as an additional source to the current water portfolio.

Non-chlorinated secondary clarifier effluent from a …

Design And Evaluation Of The Impact Of A Multi-Agent Control System (Framework) Applied To A Social Setting, Perez Antonio Perez

Open Access Theses & Dissertations

The objective of this research is to design and analyze the performance of a new mechanism to improve the advising of students in a nontraditional environment. This nontraditional environment includes: a minority serving, commuter campus with a high percentage of transfer students. Specifically, these demographics are unable to keep a tightly controlled cohort of students flowing through to the completion of the curriculum. Students in these circumstances usually have varied course loads and competing priorities due to family and financial needs or other societal responsibilities. Therefore, there is a need for an individualized approach to advising.

University administrations face challenges …

National Evaluation For Development And Exploration Potential Of Mineral Commodities In Produced Waters, Stephanie Ray

Open Access Theses & Dissertations

The U.S. Geological Survey recently updated a geochemical database consisting of data for approximately 160,000 produced waters samples, primarily from petroleum and geothermal reservoirs. Using major and trace elements from conventional and unconventional well types from the database, this Thesis provides a comprehensive, national evaluation for mineral commodity potential in produced waters. Produced waters contain virtually every naturally occurring element and can range in salinity to several times that of seawater. Despite the typical outlook to view produced waters as a waste, they have potential for natural resource development.

This Thesis provides, for each mineral commodity found in the produced …

Modeling Of Piezoelectric Traveling Wave Rotary Ultrasonic Motors With The Finite Volume Method, Ivan Arturo Renteria Marquez

Open Access Theses & Dissertations

In 1983 Toshiiku Sashida developed a new motor concept called Piezoelectric Traveling Wave Rotary Ultrasonic Motor (PTRUSM). The advantages of these motors include high torque at low speed, absence of a generated magnetic field, and high potential for miniaturization. Unfortunately PTRUSMs have some disadvantages that limit the areas of applications for these types of motors. The disadvantages are a short operating life (about 1000 hours), small output power, and the need of a complex motor controller.

On one hand, these motors have been used in satellites, mobile phones, photocopiers, robotic arms, telescopes, automobiles, and camera autofocusing. On the other hand, …

Intrinsic And Metal-Doped Gallium Oxide Based High-Temperature Oxygen Sensors For Combustion Processes, Ernesto Javier Rubio

Open Access Theses & Dissertations

Currently, there is enormous interest in research, development and optimization of the combustion processes for energy harvesting. Recent statistical and economic analyses estimated that by improving the coal-based firing/combustion processes in the power plants, savings up to ~$450-500 million yearly can be achieved. Advanced sensors and controls capable of withstanding extreme environments such as high temperatures, highly corrosive atmospheres, and high pressures are critical to such efficiency enhancement and cost savings. For instance, optimization of the combustion processes in power generation systems can be achieved by sensing, monitoring and control of oxygen, which is a measure of the completeness of …

Systems Engineering Approach To Solve Drug Violence Problem, Jagadish Thimiri Mallikarjan

Open Access Theses & Dissertations

The War on Drugs has caused cartel related violence to increase, creating a challenge for socio-political stability in Mexico. Currently, the U.S. government focuses on law enforcement measures to interdict drugs in the cartel supply lines.The basics of supply-and-demand and system dynamics approach provided a conceptual framework to understand and capture the features of interdiction in illegal drug markets, and provided important insights to solve the drug violence problem.

Ontology-Driven Integration Of Data For Freight Performance Measures, Eduardo J. Torres

Open Access Theses & Dissertations

Transportation performance measures are defined as quantitative and qualitative indicators that rely on data or information to explain mobility, congestion, safety, environmental and other factors. Though performance measures have been used for freeways and other highways, not many have been specified and applied to the freight transportation system. Recently, freight performance measures have been recommended by Federal Highway Administration to quantify the operating efficiency of the freight transportation system on existing infrastructures. This research seeks to expand this concept and to develop a comprehensive freight performance measurement framework. The expanded framework recommended in this Thesis consists of four criteria: safety, …

Microstructural Investigation Of Vintage Pipeline Steels Highly Susceptible To Stress Corrosion Cracking, Monica Adriana Torres

Open Access Theses & Dissertations

The use of pipelines for the transmission of gas offers not only efficiency, but a number of economic advantages. Nevertheless, pipelines are subject to aggressive operating conditions and environments which can lead to in-service degradation [1] and thus to failures. These failures can have catastrophic consequences, such as environmental damage and loss of life [2]. One of the most dangerous threats to pipeline integrity is stress corrosion cracking (SCC). Despite the substantial progress that has been achieved in the field, due to the complex nature of this phenomenon there is still not a complete understanding of this form of external …

Design Of A Thermal Management System For An Oxy-Methane Direct Power Extraction Combustor, Jad Gerges Aboud

Open Access Theses & Dissertations

The overarching goal of this Thesis is to present the design of a thermal management system for an oxy-methane direct power extraction combustor. The design is initiated by performing a 2D analysis on the combustor geometry and then using these results in a 3D model. This is done by using results for heat transfer coefficient and temperatures found from the 2D simulation and importing these to the 3D model. The approach used here couples the combustion process, heat transfer through the chamber wall, and fluid flow behaviors in order to observe the thermal characteristics of the combustor during operation. This …

G-Code Generation For Multi-Process 3d Printing, Callum Peter Bailey

Open Access Theses & Dissertations

Since the inception of stereolithography in the 1980s, interest in 3D printing has exploded, with desktop 3D printers now commercially accessible to the general public. In recent years, next-generation multifunctional technologies have been developed, which combine 3D printing with other technologies such as wire embedding, foil embedding, CNC machining, and robotic component placement, enabling complex parts to be made on a single multifunctional machine.

However, the complexity of these integrated processes exceeds the capabilities of established design tools. To this end, this Thesis aims to develop a multi-functional design solution that can automatically generate final control code for next-generation multifunctional …

A Discretionary Lane Changing Decision Model Based On Fuzzy Inference System, Esmaeil Balal

Open Access Theses & Dissertations

A lane changing event involves up to five vehicles: the subject vehicle, preceding and following vehicles in the original lane, and the preceding and following vehicles in the target lane. Understanding the behavior of the subject vehicle with respect to the surrounding vehicles is fundamental to the study of the safety of a lane change maneuver and for the modeling of lane changing behavior. First, the statistical properties of 10 lane changing parameters were defined and studied using the Next Generation SIMulation (NGSIM) vehicle trajectory data collected at the I-80 Freeway in Emeryville, California, and then tested with data collected …

Case Studies In Implementing Intelligent Compaction In Construction Of Earthwork, Jorge Alberto Beltran

Open Access Theses & Dissertations

The nuclear density gauge (NDG) is the current tool for field compaction quality control (QC) and quality assurance (QA) for soil and base layers in the state of Texas. The Texas Department of Transportation (TxDOT) uses this nondestructive testing (NDT) device to determine the compacted density and moisture content of earthwork and unbound aggregates. However, to provide the missing link between design and quality management parameters, an alternative stiffness-based approach would be more desirable. Intelligent Compaction (IC) is defined as continuous assessment of mechanistic soil properties (stiffness, modulus) through roller parameters (frequency, amplitude and speed) integrated with global positioning system …

Influence Of The Stress Path, Moisture, And Fine Content On Permanent Deformation Of Geomaterials, Uriel Brian Arteaga

Open Access Theses & Dissertations

Permanent deformation within the unbound granular is a predominant feature that results in the degradation and loss of serviceability to the pavement structure as the passage of traffic wheel loads accumulate. Proper characterization of the multi-layer structures is necessary to improve the rutting performance by mechanistically identifying the factors that contribute to the progression of plastic deformations. A consequence of ignoring these features results in the underestimation of the rutting potential, which amounts to premature failure. Current rutting models fail to incorporate factors such as moisture state, gradation, and stress-paths which are paramount to proper characterization of base and sub-base …

Design Of Experiments-Based Scara Robot Parameter Evaluation For Embedding Electronics Into 3d Print, Sreekara Charith Boppana

Open Access Theses & Dissertations

Additive manufacturing processes combined with enhanced technologies for electronics production enables a highly flexible manufacturing of personalized 3D electronic devices. Due to the enormous progress within the last years, these technologies made their way from prototyping towards manufacturing. The growing request for products manufactured in batch size, making use of a robot to incorporate the electronic components necessary to make functional 3-Dimensional-Structural Electronics will extend the mass production possibilities. There is significant interest in automation of a process is which parameters are influential in the occurrence of assembly defects and which adjustments should be made to those variables to reduce …

Investigation Of Ti-6al-4v Alloy Response To Atmospheric Re-Entry Exposure, Jessica Lynn Buckner

Open Access Theses & Dissertations

Ti-6Al-4V is a widely used aerospace alloy for its high strength-to-weight ratio and high operating temperature properties. Despite widespread use, titanium and its alloys have been shown to ignite in oxygen and nitrogen rich test streams. The reactivity of titanium is attributed to the high solubility for oxygen that increases with temperature, accelerating the oxidation rate and resulting in a combustion reaction. When introduced to the monatomic oxygen rich and high enthalpy re-entry environment, Ti-6Al-4V X-link components from the space shuttle Columbia exhibited accelerated oxidation and combustion behavior. Ti-6Al-4V metal plates tested in the simulated re-entry environment of an arc-jet …

Vascularization In Interconnected 3d Printed Ti-6al-4v Foams With Hydrogel Matrix For Biomedical Bone Replacement Implants, Victor Correa

Open Access Theses & Dissertations

Abstract:

Vascularization or angiogenesis on newly implanted metal orthopedic implants has remained a challenge in the field of tissue engineering. In this research, an interconnected foam structure of Ti-6Al-4V was micro-fabricated by Electron Beam Melting (EBM) technique. The foam in question has a density of 1.77g/cm3 with 60% porosity and a tensile strength of 18GPa. An Extracellular Matrix based hydrogel was added as an aqueous matrix to the foam in question. Hypoxia mimetic stress has been closely related to many wound healing biomedical applications as it increases survival and proliferation molecular signals. To that end, increased expression of Hypoxia-Inducible Factor-1α …

Materials Characterization Of Deposits On Starboard (Inboard) Elevon Actuator Shaft Recovered From Space Shuttle Columbia, Mayra Contreras

Open Access Theses & Dissertations

With the new era of space exploration upon us and the Orion spacecraft currently being tested, which would replace the Space Shuttle as the orbiter that will transport humans into space once again, safety assurance is the main component for a successful mission. Aerospace materials have always played a big role when it comes to safety assurance. Having the knowledge of what materials are suitable to keep using when designing the future spacecraft that will take humans to Mars is fundamental in order to be confident that the vehicle and all that comprises it will function as envisioned. Expanding the …

Magnesium-Based Combustion Synthesis Of Advanced Materials For Energy And Space Applications, Armando Delgado

Open Access Theses & Dissertations

As energy problems become more challenging, interest in low-energy-consuming methods for the fabrication of materials increases. Combustion synThesis is one such method because it is sustained by reaction heat release instead of external energy input. In the present work, combustion synThesis approaches are applied to the production of construction materials from lunar and Martian regolith and to the fabrication of magnesium silicide (Mg2Si), a promising thermoelectric material for high-temperature applications. In both cases, magnesium (Mg) was used as one of the main reactants and similar experimental approaches were employed.

Recently, it has been proposed to use combustion of lunar regolith …

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 …

A 38 Ghz On-Chip Antenna In 28-Nm Cmos Using Artificial Magnetic Conductor For 5g Wireless Systems, Max Ammann

Conference papers

This paper presents the first-ever millimeter wave on-chip antenna (AoC) in 28 nm CMOS technology. The addition of artificial magnetic conductor (AMC) can increase the antenna's power gain and radiation efficiency to -1.75 dBi and 22%, respectively, with an occupied area of 0.95 mm×4.75 mm at 38 GHz. This structure is intended for fully integrated single-chip nanometer CMOS transceivers for 5G communication systems.