Engineering Commons^™

Studies On Woven Carbon/Vinyl Ester Composites: Environmental Effects, Joining And Hybridization, Ricardo Garcia

Open Access Theses & Dissertations

The incessant demand for fiber reinforced polymer composites, or FRPCs, in industrial applications which desire materials that possess high strength-to-weight ratios, generates a theory-to-practice void which must be filled with scientific research. In this Thesis, woven carbon/vinyl ester composites are studied under a wide spectrum of settings and conditions. The adverse effects of sea water environment and arctic temperatures on such mentioned composites are explored in the form of moisture uptake, impact on flexural modulus, strength and structural damage. It was found that sea water saturation in general degrades the flexural strength up to 19.45%, and arctic exposure and combined …

Asset Management Support Tools To Assist Agencies In The Development Of Guardrail Preservation Programs, Sandra N. Gutierrez

Open Access Theses & Dissertations

The purpose of this Thesis is to develop a Guardrail Asset Management Framework and a Condition-Based Model to assist agencies in the development of guardrail preservation programs. Both of the guardrail asset management tools can be incorporated into an existing asset management program to assist agencies in utilizing guardrail inventory to forecast key asset management parameters such as the guardrail condition, funds necessary for maintenance and repair, backlogged funding, guardrail system value, and the guardrail sustainability ratio. Each of these parameters is described and determined for a case study involving six scenarios modeling funding and maintenance constraints that can arise …

Integrating Manufacturing Geometric Imperfections In The Inelastic Behavior Modeling Of Joints Used In Three-Dimensional Structures, Alfonso Andres Garcia

Open Access Theses & Dissertations

Three-dimensional structures follow design practices on the common assumption that joints are either rigid, or pinned. However, the non-linear behavior of engagement of the joints is required to be incorporated into the analysis. This research is intended to incorporate manufacturing geometric imperfections into the mechanical analysis of reticulated space structures jointing systems. Imperfect jointing systems deviate from the as-designed models in such a way that the location of the connecting surfaces does not follow the designed interaction path between the component elements. However, current structural analysis methodologies do not consider manufacturing geometric imperfections and often fail to consider the stresses …

On Demand 3d Printed Hybrid Scaffolds For Tissue Engineering Applications, Ivan D. Hernandez

Open Access Theses & Dissertations

A composite 3D printed polymer scaffold with inbuilt porosity and filled with a hydrogel can provide an ideal support system for cell growth, proliferation, and vascularization. Therefore, a hybrid system of 3D printed polycaprolactone (PCL) scaffold and a hydroxyapatite-based hydrogel was developed for application in the reconstruction of bone defects, which are inherently difficult to repair without any guided therapies. In the present study, a 3D printed gyroid structure of PCL allowed the loading of a higher amount of hydrogel as compared to conventionally used 3D printed mesh structure of the same volume and strut thickness. The hydrogel was composed …

Ac Susceptibility And Epr Investigations Of Superspin Dynamics In Manganese Oxide Nanoparticles, Mahesh Koirala

Open Access Theses & Dissertations

We have investigated the superspin dynamics of 5 nm and 10 nm mixed state Mn3O4 nanoparticles utilizing ac-susceptibility and electron paramagnetic resonance measurements. The out of phase component of the ac-susceptibility measurements show a magnetic anomaly below (T

Cost-Effective Recovery Of Concentrated Cooling Tower Blowdown Using The Cerro Process, Lindsey Nicole Larson

Open Access Theses & Dissertations

The Concentrate Enhanced Recovery Reverse Osmosis (CERRO) process is a seawater-RO unit that can cost-effectively achieve extremely high recoveries from water high in silica, carbonate and sulfate concentrations. This relatively new technology takes advantage of the induction time of potential foulants to recover more water than what is normally achievable with a conventional desalination system. The scope of the project was to evaluate the efficiency of the CERRO process as a pilot study using cooling tower blowdown which varied in water quality parameters daily. It was found that the CERRO pilot could successfully achieve 85% recovery, and the main limitation …

Quantification Of The Impact Of Asphalt Pavement Conditions On Gas Emissions, Oscar Daniel Gonzalez Calvo

Open Access Theses & Dissertations

This research develops a methodology to quantify the impact of asphalt pavement conditions on vehicular gas emissions based on statistical analysis to correlate the relationship between asphalt pavement roughness and gas emissions. ANOVA (Analysis of Variance) hypoThesis tests were used to compare the factors affecting the results. The roughness was measured with the International Roughness Index (IRI) using a profilometer provided by TxDOT and the gas emissions were measured with a Portable Emission Measurement System (PEMS).

This research also presents the savings obtained in gas emissions using different maintenance and rehabilitation strategies established by TxDOT (Preventive Maintenance, Light Rehabilitation, Medium …

Design Of A 2000 Lbf Lox/Lch4 Throttleable Rocket Engine For A Vertical Lander, Israel Lopez

Open Access Theses & Dissertations

Liquid oxygen (LOX) and liquid methane (LCH4) has been recognized as an attractive rocket propellant combination because of its in-situ resource utilization (ISRU) capabilities, namely in Mars. ISRU would allow launch vehicles to carry greater payloads and promote missions to Mars. This has led to an increasing interest to develop spacecraft technologies that employ this propellant combination.

The UTEP Center for Space Exploration and Technology Research (cSETR) has focused part of its research efforts to developing LOX/LCH4 systems. One of those projects includes the development of a vertical takeoff and landing vehicle called JANUS. This vehicle will employ a LOX/LCH4 …

Design Of A 1 Megawatt Heat Input Direct Power Extraction System For Advanced Topping Cycles, Brian Matthew Lovich

Open Access Theses & Dissertations

Power development has become a standard for living; as such more efficient and cleaner methods are desired. One such method is that of the direct power extraction system utilizing Magnetohydrodynamic properties. This paper will discuss the combustor designed and developed for a direct power extraction system at the 1 MW heat input range. A short history of the power systems utilized with a focus on the direct power class will be conducted in the first chapter to give insight into the benefits of using the direct power system. Then a literature review the fundamentals of direct power systems will be …

Protonic Conductors For Intermediate Temperature Fuel Cell Electrolytes: Superprotonic Csh2po4 Stabilization And In-Doped Snp2o7 Structure Study, Heber Jair Martinez Salinas

Open Access Theses & Dissertations

Proton conductor solid electrolytes CsH2PO4 and In-doped tin pyrophosphate have been investigated as candidates to fill a gap of suitable electrolytes for fuel cells at the intermediate temperature range due their unusually high conductivities between 200 and 300 °C. Unfortunately, in the case of CsH2PO4, complicated experimental conditions, like a humidified environment, or high pressure, are needed to preserve the sought high conducting phase.

In the first stage of this work, X-ray diffraction on CsH2PO 4 samples performed in air, and under normal conditions of humidity and pressure, evidence of the cubic phase of CsH2PO4 was observed during short intervals …

Structural And Mechanical Characterization Of Nanocrystalline Tungsten And Tungsten-Based Alloy Thin Films For Extreme Environment Applications, Gustavo Martinez

Open Access Theses & Dissertations

Extreme environments associated with nuclear applications often results in degradation of the physical, mechanical and thermo-mechanical properties of the materials. Tungsten (W) exhibits unique physical and mechanical properties, which makes tungsten a good candidate for nuclear applications; however, intrinsic W exhibits low fracture toughness at all temperatures in addition to a high ductile to brittle transition. In the present work, nanocrystalline W, W-Y and W-Mo alloys were nanoengineered for nuclear applications. Nanocrystalline tungsten coatings with a thickness of ~1 µm were deposited onto Silicon (100) and Sapphire (C-plane) using RF and DC sputtering techniques under various growth conditions. Yttrium content …

Hardware Development And Testing For Lox/Lch4 Rocket Engine, Pedro Nunez

Open Access Theses & Dissertations

The University of Texas at El Paso (UTEP) Center for Space Exploration and Technology Research (cSETR) has focused its research efforts on developing LOX/LCH4 propulsion systems. As part of the Janus Sub-orbital vehicle program, UTEP is developing a 2000 lbf throttleable rocket engine (Chrome X). The first iteration of this engine design will be geared for further optimization towards a flight engine. Components like electric motors, valves, and sealants have been selected to achieve throttle ability and sealing of the engine. These components play a crucial part on the engine to be able to have a successful firing. As part …

Compressive Vector Reconstruction: Hypothesis For Blind Image Deconvolution, Alonso Orea Amador

Open Access Theses & Dissertations

Alternative imaging devices propose to acquire and compress images simultaneously. These devices are based on the compressive sensing (CS) theory. A reduction in the measurement required for reconstruction without a post-compression sub-system allows imaging devices to become simpler, smaller, and cheaper. In this research, we propose a new algorithm to compress and reconstruct blurred images for CS imaging devices. Blur effect in images is common due to relative motion, lens, limited aperture dimensions, lack of focus, and/or atmospheric turbulence. Our intention is to compress a blurred image with CS techniques and then reconstruct a blur-free version using the proposed algorithm. …

Automatic Patch Classification And Diffusion In Adaptive, Luis Alonso Ponce

Open Access Theses & Dissertations

Multi-Frame image restoration is a form of Super-Resolution (SR) which consists of combining multiple Low-Resolution (LR) images in order to reconstruct a single High Resolution (HR) image. In this Thesis we improved a spatially-adaptive SR scheme, based on the framework of Optimal Recovery (OR), whereby the block-by-block processing is done based on the properties of the corresponding local LR image data patches. The bandwidth parameter is adapted based on the local variance of each corresponding block from all LR images that contribute to the HR image block to be reconstructed. Also, an optimal regularization parameter needs to be chosen for …

A Cubesat Communication System Development For Gto Mission, Ashiqur Rahman

Open Access Theses & Dissertations

Tracking, telemetry and command (TT&C) systems on traditional small satellites have advanced significantly in last few decades. The capabilities, requirements and expectations of the communication system have been increased significantly for the smaller satellites. Small satellites are now performing the tasks near to the bigger satellites which increases the dependency on the communication system in terms of reliability and data management. This Thesis paper will focus on development of the communication system of a 1U cube Satellite named Orbital Factory II (OFII). The satellite will be launched into a geostationary transfer orbit (GTO) onboard a United Launch Alliance (ULA) Atlas …

Flexible Analysis Of Creep Rupture Database And Accelerating The Acquisition Of Creep Rupture Data, Christopher Ramirez

Open Access Theses & Dissertations

A comprehensive statistical analysis of creep data is a difficult task because there are many layers of uncertainty for a given dataset. Sources of uncertainty are inherent in both the databases that provide data, and the data themselves. Additionally, creep rupture predictions made with time-temperature parameter (TTP) models add an additional layer of uncertainty due to the fundamentally different ways in which each TTP model predicts creep behavior. A set of guidelines from the ECCC currently exist for such analyses, but they are best suited for narrowly-defined datasets. In this study, a broader set of guidelines are developed to analyze …

Safety Airway For Small Unmanned Aerial Vehicles Using A Gas Particles Behavior Analogy, Pablo Rangel

Open Access Theses & Dissertations

The United States Federal Aviation Administration (FAA) implemented the Part 107 legislation to allow the flight of Unmanned Aerial Vehicles (UAV) for commercial use (i.e. package deliveries, power transmission line inspections, etc.) in the National Airspace System (NAS). As a consequence of the newly introduced rules, there is an increased risk for accidents involving injured bystanders or damaged to property. The work within this document defines a UAV to UAV safety distance model that acts as a range sensor enabled "elastic bubble". The length of the UAV safety bubble contracts and expands upon changing airway wind speed conditions. It also …

Three Dimensional Finite Element Model For Residual Stresses In Parts Manufactured By Slm And Ebm, Jesus Gerardo Reyes Schuldes

Open Access Theses & Dissertations

Ongoing research efforts in industry and academia have a focus on optimal build parameters that lead to suitable mechanical properties with minimum defects in parts manufactured by powder bed fusion additive manufacturing technologies, such as Electron Beam Melting (EBM) and Selective Laser Melting (SLM). Additional and significant resources, including energy, time, and money are spent as a result of obligatory post-manufacturing heat and/or mechanical treatment to ensure optimum mechanical properties. One intrinsic fault in these technologies, which contributes to the need for treatment processes after part fabrication, is the creation of residual stresses during these processes. Residual stresses remain in …

Risk Mitigation In The Supply Chain Caused By Multitple Phase-In And Phase-Out Components Using Simio Simulation, Anabel Renteria Marquez

Open Access Theses & Dissertations

Manufacturing is constantly changing, adapting to new technologies and making improvements on their products design, while dealing with engineering design changes can represent an improvement or savings to the company it can also end up as a huge risk of disruption in the Supply Chain if there is not a safety phase-in and phase-out components transition because the network became more complex and affected processes needs to be revalidated, here comes the importance to set up an strategy to mitigate any possible risk and maximize total revenue.

A case study for a two tiers level Supply Chain system is evaluated …

The Former Asarco Demolition Fallout, A Post Study On Lead Soil Concentrations And Environmental Agents Of Redistribution In El Paso, Texas, Stephanie A. Robinson

Open Access Theses & Dissertations

The former El Paso ASARCO Smelting and Refining Co. operated between 1877 and 1999, the pyrometallurgic activity was estimated to have discharged excess of a 1,000 tons of lead (Pb) into the atmosphere from 1969-71. It was estimated 96 tons of (Pb) were emitted on an annual basis from the standing ore and fluid beds. The Environmental Protection Agency (EPA) determined that lead (Pb) is the heavy metal of the highest concentration within the vicinity of the smelter. After the smelter production ceased, flash flooding common to the southwest, such as the 2006 historic flood, increased transportation of superficial contaminants …

Microelectromechanical Systems Inertial Measurement Unit As An Attitude And Heading Reference System, Francisco Javier Salcedo Ortega

Open Access Theses & Dissertations

Microelectromechanical systems inertial measurement units (MEMS IMU) are an accessible technology that can be used as an attitude and heading reference system (AHRS); they are low cost and functional enough to be used in many Inertial Navigation Systems (INS). However, the gyroscope component on the IMU tends to severely drift over time without the use of filtering or other navigation systems reference such as a Global Positioning System (GPS) device. This Thesis is focused on working with a variety of IMUs to describe the accuracy, precision, and error propagation. It also works as an introductory guide to the world of …

Pyroelectric Ceramics As Temperature Sensors For Energy System Applications, Jorge Luis Silva

Open Access Theses & Dissertations

Temperature is continuously monitored in energy systems to ensure safe operation temperatures, increase efficiency and avoid high emissions. Most of energy systems operate at high temperature and harsh environments to achieve higher efficiencies, therefore temperature sensing devices that can operate under these conditions are highly desired. The interest has increased in temperature sensors capable to operate and in harsh environments and temperature sensors capable to transmit thermal information wirelessly. One of the solutions for developing harsh environment sensors is to use ceramic materials, especially functional ceramics such as pyroelectrics. Pyroelectric ceramics could be used to develop active sensors for both …

Optimization Of Neural Network Architecture For Classification Of Radar Jamming Fm Signals, Alberto Soto

Open Access Theses & Dissertations

Radar jamming signal classification is valuable when situational awareness of radar systems is sought out for timely deployment of electronic support measures. Our Thesis shows that artificial neural networks can be utilized for effective and efficient signal classification. The goal is to optimize an artificial Neural Network (NN) approach capable of distinguishing between two common radar waveforms, namely bandlimited white Gaussian jamming noise (BWGN) and the ubiquitous linearly frequency modulated (LFM) signal. This is made possible by creating a theoretical framework for NN architecture testing that leads to a high probability of detection (PD) and a low probability of false …

Raman Microscopic Analysis Of Internal Stress In Boron-Doped Diamond Thin Films, Emma M.A. Sundin

Open Access Theses & Dissertations

The correlations between induced stress on undoped and boron-doped diamond (BDD) thin films, sample chemical composition, and fabrication substrate are investigated in this study via confocal Raman microspectroscopic analysis. Stability of BDD films is relevant to fast-scan cyclic voltammetry, as film delamination and dislocation of BDD-coated electrodes that can occur during neurosurgical electrode implantation can negatively impact the biosensing reliability of this technique. Electrodes were fabricated by coating cylindrical tungsten rods using a custom-built chemical vapor deposition reactor. The results of the analysis reveal a direct correlation between regions of pure diamond and enhanced material stress, as well as preferential …

Structural And Electrical Characterization Of Tin Oxide Resistive Switching, Arka Talukdar

Open Access Theses & Dissertations

Resistive switching in metal oxide is a phenomenon in which the metal oxide changes its resistance upon application of electric field and thus giving two states; high resistance state (HRS) and low resistance state (LRS). Many metal oxides have been investigated however very little is known about unipolar resistive switching in SnO2 though it has shown excellent resistive switching characteristics. Defects in the material play a vital role in resistive switching of the metal oxides. In this work, the role of defects in resistive switching of SnO2 are investigated in Ti/SnO2/Au structures. Two methods were used to control the concentration …

Redesign Of A Volume Adjustable Transtibial Prosthetic Socket, Samuel Terrazas Quezada

Open Access Theses & Dissertations

Recent research and development in prosthetics have aimed at improving socket designs and components to mimic more efficiently the human body. One such innovation is the Aperture Socket, a low-cost volume adjustable prosthetic socket. During the validation stage of its development, the Aperture Socket successfully demonstrated that it could compensate for volume changes, but various improvements on use and comfort were identified. This project develops and tests a redesign of the Aperture Socket previously developed for amputees in developing countries and subsequently patented and licensed to LIMBS International, Inc.

The first phase of this study was the creation of various …

The Design, Construction And Operation Of System To Analyze The Decomposition Gases Of Af-M315e, Jonathan Alejandro Valenzuela Brok

Open Access Theses & Dissertations

With the current trend of aerospace organizations towards developing green monopropellant, the key priority is to eliminate the use of highly dangerous monopropellants, such as hydrazine. In that vein, one of the best candidates to replace hydrazine is a monopropellant known as AF-M315E. AF-M315E was developed by the Air Force and is currently being advanced by NASA and private corporations for use on various satellite platforms, with NASA looking to launch a test satellites part of their Green Propellant Infusion Mission (GPIM), Raytheon providing support on the Missile Defense Agency's Network Centric Airborne Defense Element (NCADE) program and Department of …

Design Optimization For Heat Dissipation In Polymer Additive Manufacturing With Joule Heating, Tania Alejandra Ventura

Open Access Theses & Dissertations

Nowadays, the use of additive manufacturing (AM) is mainly focused on the production of prototypes with the purpose of evaluating a design. This industry has become a subject of constant reinvention; in fact, an emerging application of AM is focused on creating parts with embedded electronics. However, the development of both traditional and additive manufactured electronics has led to an increase in power densities and size reduction. Consequently, thermal management has become essential in electronics, as overheating decreases reliability of the component leading to a premature failure.

In this study, a polycarbonate component design with integral electrical circuitry that is …

Comprehensive Finite Element Modeling Of Ti-6al-4v Cellular Solids Fabricated By Electron Beam Melting, Edel Arrieta

Open Access Theses & Dissertations

Additive manufacturing permits the fabrication of cellular metals which are materials that can be highly customizable and possess multiple and extraordinary properties such as damage tolerance, metamorphic and auxetic behaviors, and high specific stiffness. This makes them the subject of interest for innovative applications. With interest in these materials for energy absorption applications, this work presents the development of nonlinear finite element models in commercial software platforms (MSC Patran/Nastran) that permit the analysis of the deformation mechanisms of these materials under compressive loads. In the development of these models, a detailed multiscale study on the different factors affecting the response …

Image Data Mining For Quality Control Of Nanofiber Reinforced Piezoelectric Nanocomposites Based On Sem Images, Zhonghua Hu

Open Access Theses & Dissertations

Recently, portable and wireless nano-scaled devices have been widely used in environmental monitoring, medical implants, defense technology, industrial safety, and personal electronics, such as the nanowire-based gas and chemical sensors and programmable nanowire circuit for nano-processors. There has been an increasing demand for high energy density capacitors that can be engineered for various applications in advanced devices. In it, piezoelectric nanofiber materials play critical role in producing new products. A piezo-ceramic polymer composite contains a polymer of high dielectric strength and high permittivity ceramic inclusions, making it well suited as a high energy density capacitor. Furthermore, the research shows that …