Engineering Commons^™

Development Of A High Pressure Optically Accessible Combustor And Shear Co Axial Injector, Christopher David Navarro

Open Access Theses & Dissertations

A trend in the last decade in the field of propulsion and rocketry is leaning toward the use of the combination of Liquid Methane and Liquid Oxygen as propellant fuels. This is in contrast with the earlier trend of using Hydrogen systems and toxic hypergolic systems. The Multi-Purpose Optically Accessible Combustor (MOAC) and Shear Coaxial injectors have been developed to investigate injector design and combustion research involving Oxygen and Methane propellants. The MOAC is intended for the experimentation and research of combustion of liquid and gaseous propellants. Development of the MOAC system and versatility to use a number of injector …

Development Of Models To Estimate Modulus And Permanent Deformation Of Texas Bases, Eric Navarro

Open Access Theses & Dissertations

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Use Of Environmental Isotope Tracer And Gis Techniques To Estimate Basin Recharge, Abdulganiu A.A. Odunmbaku

Open Access Theses & Dissertations

The extensive use of ground water only began with the advances in pumping technology at the early portion of 20th Century. Groundwater provides the majority of fresh water supply for municipal, agricultural and industrial uses, primarily because of little to no treatment it requires. Estimating the volume of groundwater available in a basin is a daunting task, and no accurate measurements can be made. Usually water budgets and simulation models are primarily used to estimate the volume of water in a basin.

Precipitation, land surface cover and subsurface geology are factors that affect recharge; these factors affect percolation which invariably …

Nanoprobe I-V Characterization Of Cdte/Cds Micro And Nano-Patterned Solar Cells, Heber Prieto

Open Access Theses & Dissertations

This thesis presents a novel way to characterize micro and nano patterned cadmium telluride thin film solar cells via a nano-probe system. A historical review of CdTe-based solar cells is presented first followed by review of the technology developed to produce the patterned CdTe cells. A detailed presentation is then provided on the use of a Zyvex nanoprobing system to characterize the patterned solar cells. The I-V response of micro- and nano-patterned solar cells stimulated under different e-beam conditions is presented and analyzed. Suggestions of how to improve the technique are provided. This work documents, for the first time, the …

The Influence Of Build Parameters On The Microstructure During Electron Beam Melting Of Ti6al4v, Karina Puebla

Open Access Theses & Dissertations

With the demand of devices to replace or improve areas, such as: electronic, biomedical and aerospace industries. Improvements in these areas of engineering have been in need due to the customer’s needs for product properties requirements. The design of components must exhibit better material properties (mechanical or biocompatible) close to those of any given product. Rapid prototyping (RP) technologies that were originally designed to build prototypes may now be required to build functional end-use products. To carry out the transition, from RP to rapid manufacturing (RM), the available materials utilized in RP must provide the performance required for RM. The …

Position Sensitive Device With Gaussian Response, Sinohe Rodriguez

Open Access Theses & Dissertations

Much work has been done in improving the linearization of position sensitive devices, PSDs. However, a novel way of position detection using Gaussian filters has recently been developed. An obvious extension of this approach is possible via the electro-optical implementation of the Gaussian filters. This thesis proposes a PSD that has such a Gaussian output response to an incident light spot moving across its surface. The proposed device is based on a simple and inexpensive p-n junction. The device is simulated using finite-difference frequency-domain numerical analysis within Matlab.

Low Energy Disruption Of Lipid Containing Biomass, Joaquin Rodriguez

Open Access Theses & Dissertations

Lipid containing biomass from microalgae has received recent research interest as a renewable and sustainable feedstock for biofuel production. Algae is known to offer as much as 30 times the energy density than corn based ethanol, the current world standard for biomass based liquid transportation fuels. The development of large scale systems and methods of extracting lipids from microalgae is still in the early stages of development and significant increases in efficiency and reduction in costs are necessary to substantiate algae as a feasible alternative source of fuel. Traditional conversion of algae feedstock into a refineable feedstock for biofuel can …

Oxidation Of Borides And Carbides With Y2o3 And Ta Additions, Salvador Manuel Rodriguez

Open Access Theses & Dissertations

The study presented here describes an investigation of an oxidation scale of a fully-sintered Y2O3-ZrB2-TiC composite exposed in air at 1173K. Upon oxidation of the boride/carbide, a ZrO2-TiO2 was expected to form similar to the ZrO2-SiO2 dual scale of an oxidized ZrB2-SiC. The 47wt% Y2O3-38wt%ZrB2-16wt%TiC composite formed a dual scale consisting primarily of an Y2O3-ZrO2-TiC inner scale with an outer scale of ZrO2-TiO2-Y2O3.

The samples oxidized with a parabolic layer growth allowing the calculation of the effective diffusion coefficient indicating that the oxidation was controlled by oxygen ingress through primarily the ZrO2-Y2O3 phase. The oxygen potential between the inner layer …

Identification Of Rework Station Location To Enhance Reworkability Using Design For Disassembly, Juan Alejandro Saavedra

Open Access Theses & Dissertations

Rework stations are commonly established as part of each assembly stations causing the material flow of the process to be constantly interrupted. Another option is to place the rework station at the end of the production, but this is not cost effective. This breakeven point between reworkability and cost methodology has been proposed in this thesis to identify the location of a single rework station in an assembly line in order to enhance reworkability using the Design for Disassembly (DfD) principles. The methodology uses the 17 guidelines of DfD in a manufacturing scenario in order to propose a reworkability index …

Determination Of The Dynamic Behavior Of Subjects With Diabetic Neuropathy, Luis G. Sagarnaga Lopez

Open Access Theses & Dissertations

The diabetic foot is one of the most feared complications of diabetes [3]. Causes of a diabetic foot come from many disorders including diabetic neuropathy, peripheral vascular disease, charcot's neuropathy, foot ulceration, and limb amputation [4]. Statistics have revealed that 8.3 percent of population in the U.S. is affected by diabetes in 2010, i.e., 25.8 million people. About 60 percent to 70 percent of people with diabetes have mild to severe forms of nervous system damage [13]. There is an enormous impact on the physical and mental health of patients who suffer from diabetes.

This research was to determine the …

Investigation On A Gas-Solid Fluidized Bed Hydrodynamics Using A Non-Intrusive Technology To Visualize Flow Field, Md Rashedul Hasan Sarker

Open Access Theses & Dissertations

The biggest challenge for 21st century is to fulfill global energy demand and at the same time reduce detrimental impact on environment. Gasification technology can meet the requirement and also reduce emission without compromising its performance. In coal gasification, instead of burning coal completely a partial combustion takes place with presence of steam and limited amount of oxygen. In this controlled environment a chemical reaction takes place and produces a mixture of clean synthetic gas. Gas-solid fluidized bed is one type of gasification technology. During gasification mixing behavior of solid (coal) and gas and their flow pattern very complicated to …

Evaluation Of Non-Nuclear Devices In Measuring Moisture Content And Density Of Soils, Martin Jesus Sotelo

Open Access Theses & Dissertations

The objective of this report was to assess the ability of several different devices to measure moisture content and dry density of various compacted geomaterials. The experimental research involved the testing of different subgrade soils and one base material. More than a dozen specimens, 2 ft in height and 1.5 ft in diameter, were constructed to evaluate the Transtech SDG 200, Purdue TDR, and the Decagon 10 HS moisture content sensor. The Speedy Moisture Tester and DOT600 Roadbed Water Content Meter were also evaluated using individual soil samples. All materials were tested at five different moisture contents, but at their …

Control Of A Robotic Prototype Multi-Axis Synergistic System, Julio A. Torres

Open Access Theses & Dissertations

Balance is an ability that every person has and uses in normal daily life, to walk, run, stand, dance, etc. However, there are people who suffer a kind of balance impairment. The Computerized Dynamic Posturography (CDP) is technique in balance rehabilitation, where the patient is asked to stand on a moving platform that is equipped with sensors that measure how well you maintain your balance. In this thesis, a new CDP mechatronic system, the Multi-Axis Synergistic System (MASS), for balance assessment is being developed.

As a first stage and as the objective of this research work the transferable control algorithm …

Development Of An Electronic Vehicle Miles Travelled Toll Model, Marketa Vavrova

Open Access Theses & Dissertations

This thesis presents the reasons why the fuel tax is no longer a viable source of revenues and suggests new sources of funding. One possibility is to replace the fuel tax with a distance-based toll applied nationwide. Vehicle miles travelled (VMT) fee is compared to the fuel tax, and the relationship between road infrastructure spending and fuel taxation in the United States (U.S.) and the European Union (EU) is explored. Also the European approach to taxation and tolling is described and compared to the situation in Texas.

The development of a statewide distance-based toll model to estimate the feasibility of …

A Study Of International Wastewater Challenges And Policy In The Tijuana River Watershed, Gloria Ann Villaverde

Open Access Theses & Dissertations

Since the 1930s, untreated and undertreated sewage from Tijuana, Baja California, México has been released into the Tijuana River Watershed causing contamination of the water supply, crops, the Tijuana Estuary and California beaches. Passage of the North American Free Trade Agreement (NAFTA) has exacerbated the problem by causing population and industrial growth explosions for which there have been insufficient services to meet the needs of the people. The waters of the Tijuana River flow (from México) north over the International Border, into the Tijuana Estuary, discharge out to the Pacific Ocean and often flow north, up the California Coast; therefore, …

Implementation Of Evolutionary Algorithms On The Power Industry And Aviation Security, Anuar Jesus Aguirre

Open Access Theses & Dissertations

The main objective of the power electric power grid is to supply reliable electricity to all the customers. Customers could be industrial, commercial, household, transportation and others. The power grid is a complex and large, and it formed by the conjunction of the generation, transmission and distribution system. The present research is focused in power distribution system. A new component replacement analysis method to solve component replacement problems for complex electricity distribution systems using Genetic Algorithms is developed. In the present model a Taylor series expansion is used to approximate the associated opportunity cost for each component in the system. …

Microscopic And Spectroscopic Analysis Of Wo3 And Ti-Doped Wo3 Thin Films, Young Taek Yun

Open Access Theses & Dissertations

Tungsten oxide (WO3) has been a subject of high interest for its unique properties, and recently for its importance in different types of industrial applications which ranges from non-emissive displays, optical, microelectronic, catalytic/photocatalytic, humidity, temperature, gas, and biosensor devices. In this study, WO3 and Ti doped thin films were prepared using radio frequency magnetron reactive sputtering at different substrate temperatures ranging from room temperature to 500 ºC in increments of 100 ºC. After forming a hypothesis based on knowledge of established WO3 properties, we attempt in this work to investigate how the doping influences the roughness and the mean grain …

Strategies To Improve And Preserve Flexible Pavements At Intersections, Imad N. Abdallah

Open Access Theses & Dissertations

Many rural intersections originally constructed with thin untreated flexible base and hot mix or a two-course surface treatment experience severe pushing, shoving and rutting. These failures cause an extremely rough surface that can cause damage to small vehicles and potentially cause motorists to lose control of their vehicle. These distresses almost always result in complete failure of the existing pavement that must be repaired several times during the life of the roadway by maintenance forces. Pavement sections constructed with the same materials adjacent to the intersection perform adequately until the approach (approximately 150 ft in advance) of the intersection and …

Electrochemical Behavior Of Zinc, Carlos E. Castillo

Open Access Theses & Dissertations

The investigation focused on the corrosion of galvanized steel exposed to soil. The primary objective of the study was to develop a technique for monitoring the corrosion behavior of samples in the field by measuring the potential and current with respect to time (or electrochemical noise). Electrochemical electrodes were designed to simulate the galvanized steel in contact with thin electrolytes which are usually generated in soils as they collect and drain rain water depending on soil porosity.

The corrosion behavior of the galvanized steel was also studied by using electrochemical impedance spectroscopy (EIS) coupled with potentiokinetic scans to predict the …

Implications Of Surface Runoff Recharge In Semi-Arid Regions On Groundwater Sustainability, Omar M. Al-Qudah

Open Access Theses & Dissertations

Amargosa Desert, Nevada regional groundwater studies show that the surface runoff infiltration occurring in the arroyos following runoff producing storms, and this infiltration is considered to be a major source of groundwater recharge. Groundwater infiltration through alluvium was investigated in the Amargosa Desert using borehole drill cuttings, groundwater chemistry, and applying a novel method for collecting runoff water. The sampling process included sediment, precipitation, and runoff water. In total, 176 runoff, 182 sediment, and 45 precipitation samples were collected between January, 2009 and January, 2011.Water chemistry, chloride concentrations, and stable isotopes of water collected from specially designed runoff samplers, placed …

Spatio-Temporal Cardiac Pacing Sites Localization And Time Varying Pericardium Potential Maps Projection Using Ecg Precordial Leads And A Single Moving Dipole Model, Jaime R. De La Cruz

Open Access Theses & Dissertations

A novel non-invasive method for the spatiotemporal localization of the sites of strongest cardiac activity, and for the creation of time varying Pericardium Potential Maps (PPM), with the use of patients' ECG precordial leads, is proposed in this Thesis study. Compared to previous studies, which analyze electrocardiograms in either time domain or spatial domain, the proposed method has the advantage of a simultaneous spatiotemporal electrocardiograph analysis and a 3-D visualization of pericardium potentials maps, as well as, the pericardium surface polarization patterns during the cardiac cycle. The spatial properties added to the electrocardiogram allow for the analysis of specific regions …

Assessment And Evaluation Of Peripheral Neuropathy From Diabetic Mellitus Using Systems Analysis Approach, Oscar Alonso Espino

Open Access Theses & Dissertations

Currently in America 1 out of every 10 residents suffers from diabetes, and this tendency is likely to grow up to "1 of every 3" by the year [6]. Diabetes exhibits several complications. In 2005, the lead cause of stroke and heart disease was diabetes, 68% of the cases [1]. In 2008, 44% of kidney failure was associated with diabetes [1]. 60 to 70 % of cases of diabetes have a mild to severe nervous system damage [1]. Diabetic patients who have developed peripheral neuropathy tend to also develop foot ulceration. In an advanced stage a foot ulcer can lead …

Experimental Study Of Thermoelectric Properties For Randomly Distributed Carbon Nanotubes And Silicon Carbide Nanoparticles, Onasis Garcia

Open Access Theses & Dissertations

In this experimental study, the thermoelectric (TE) properties of carbon nanotubes (CNTs) and Silicon carbide (SiC) nanoparticles have been investigated. Nanoparticles were randomly disrtibuted on a non-conductive glass or quartz substrate. The carbon nanotubes used were single-walled and multi-walled type, consisting of approximately 60% semiconducting 40% metallic tubes. The experimental design is analogous to that of a thermocouple measurement, with the nanoparticle layers creating hot and cold joints with a dissimilar metal Alumel (Ni-Al). Voltage (mV), current (μA) and resistance (Ω) values were measured with respect to temperature (°C), and Seeback coefficient values were also calculated in parallel. Summarized results …

Enterprise Transformation Through A Zachman-Bayesian Framework To Improve Efficiency & Productivity, Ramakanth Gona

Open Access Theses & Dissertations

Although organizations are aware of the benefits of enterprise architectures models, organizations have difficulties determining deficiencies in their business architecture. Organizational assessment tools often do not achieve expectations as sold to management. Performance measures often fail to properly represent necessary holistic measurements. Methods for capturing deficiencies in current business models and deterring improvements to optimize business processes are rare. This thesis develops a new experimental architecture modeling approach for enterprise transformations. The approach is efficient in capturing deficiencies and finding correlations which can become targeted goals for improvements. The Zachman enterprise architecture framework provides a holistic view of organizational models …

Preparation And Characterization Of Iron Oxide And Hydroxide Based Nanomaterials, Guillermo Carbajal Franco

Open Access Theses & Dissertations

Iron (Fe) oxides and hydroxides are common and abundant materials. They exhibit diverse crystal structures, properties and phenomena by virtue of which they find a wide range of scientific and technological applications. Controlled growth and manipulation of the specific structure and electronic behavior to meet the requirements of a given application is a challenging problem in view of many possible phases and composition of the resulting materials. The preparation method and experimental conditions will, therefore, significantly affect the properties and performance of Fe oxides and hydroxides. The goal of the project is to obtain Fe-based oxide/hydroxide catalytic materials and to …

Modeling Impulse Oscillometry Data: Using Augmented-Ric And Extended-Ric Respiratory Impedance Model Paramaters To Track Pulmonary Health And Disease, Carlos Domingo Ramos Rocha

Open Access Theses & Dissertations

Respiratory diseases are a great health concern. Early detection of disease could greatly improve quality of life and yet the most common pulmonary function test can be an unreliable diagnostic method, especially in the case of children. A reliable method of detecting and assessing small airway impairment could greatly help with timely diagnosis. This research approaches this problem by taking Impulse Oscillometry (IOS) data and its model-derived parameters and assessing their utility in tracking respiratory function and more specifically, small airway function.

This research first describes the use of electric circuits as models to describe lung properties at distinct regions …

Psychophysical Similarity Based Feature Selection For Nodule Retrieval In Ct, Ravi K. Samala

Open Access Theses & Dissertations

The emerging paradigms in cancer research indicate the need for a multi-perspective and multi-modal screening approach for early lung cancer diagnosis to increase the probability of clinical resection. Currently no standalone screening methodology is proved to suffice for a clinical diagnosis. Computed tomography has been proved to present abnormality at an early stage with less impact on survival rate in population studies. Nevertheless, because of its non-invasive characteristic, it can be used for diagnosis, prognosis and visualization of tumor. Studies have shown that Computer aided diagnosis (CAD) as a second reader can perform in a similar capacity as a radiologist. …

Impulse Oscillometric Features And Parsimonious Respiratory Models Track Small Airway Function In Hispanic And Anglo Children, Erika Guadalupe Meraz Tena

Open Access Theses & Dissertations

Asthma is an inflammatory condition of the peripheral (small) airways resulting in airway hyper-reactivity and, among other symptoms, airflow obstruction. It is the most prevalent chronic respiratory disease in children. Reliable and patient-friendly instruments and methods are required to help pulmonologists accurately detect asthma and Small Airway Impairment (SAI) with acceptable clinical accuracy, specificity and sensitivity. Impulse Oscillometry System (IOS) based on the Forced Oscillation Technique (FOT) has been successfully used to measure lung function in children with a high degree of sensitivity and specificity to SAI and Asthma. IOS is a patient-friendly lung function to measure the mechanical impedance …

An Investigation Into The Effect Of Blood Glucose Level Changes On Lf/Hf Parameter Of Hrv Signal In Non-Diabetic And Diabetic Individuals, Reza M. Amanipour

Open Access Theses & Dissertations

The analysis of time duration between consecutive R waves of electrocardiogram (ECG) is a standard method to evaluate the variations in heart rate. The physiological literature reveals that blood glucose levels modulate the autonomic nervous system (ANS) activity and heart rate variability (HRV) is representative of the cardiovascular autonomic function. In the research, an investigation was carried out to investigate the relationship between HRV signal measures derived from ECG and arterial blood glucose changes in five non-diabetic and five diabetic individuals during normoglycemic and mildly hyperglycemic conditions. A CleveLabs BioCapture wireless device was used to acquire ECG signals from ten …

Separation Of Humic Matter From Groundwater Via Anion Exchange Resin: Comparison Of Bead And Powder Form, Sandra June Everett

Open Access Theses & Dissertations

This work describes a comparison of a bead and powder form of anion exchange resin for removing humic matter from groundwater. The materials and procedures described herein involve a manufactured dry humic matter and two forms of the same anion exchange resin. Spectroscopy was the chosen procedure for analysis of organics.

Preliminary experiments were required to gain a better understanding of the materials and to prepare the best conditions for actual experimental research. Five concentrations of humic acid were used for experimental purposes at 0.5, 1, 5, 10 and 20 mg/L. Three concentrations of resin were used: 500, 750 and …