Engineering Commons^™

Characterization Of High Resolution Range And Doppler Chaotic Ladar, Berenice Verdin

Open Access Theses & Dissertations

Compared to high range resolution radar systems, chaotic LADAR (laser detection and ranging) has the potential of providing an increase in range-Doppler resolution by several orders of magnitude.

The purpose of this project is to determine system parameters and signal processing schemes required to build a high resolution chaotic LADAR. Specifically, the LADAR is based on a semiconductor laser that generates a wideband chaotic signal via optical feedback. The behavior of the laser output is modeled by changing the control parameters of the delay differential equations that dictate the behavior of the laser output. Depending on the feedback level and …

Impacting Testing Of High Temperature Ceramics Through The Use Of A Vitiated Heater For Hot And Cold Fire Collisions, Adrian Trejo

Open Access Theses & Dissertations

Material testing is a crucial step during the design process as particular materials serve as safety and life saving conditions. In this study, a MoSi2 is chosen as the target specimen to undergo impact under high temperatures. An impact apparatus is designed and constructed for the purpose of propelling alumina particles at high velocities. A nozzle using compressed nitrogen gas is used to fire the particle at the desired velocities. Due to the possibility of thermal shock occurring at higher temperatures, a separate nozzle utilizing vitiation heating is designed to fire the particle at equally higher temperatures to prove the …

Silica Removal From Brine By Using Ion Exchange, Carlos R. Acevedo

Open Access Theses & Dissertations

Local governments have been forced to look for additional water sources to satisfy the ever increasing demand for fresh water. Very often, the new water sources such as the underground water in continental territories have high salt content. Currently, reverse osmosis technology (RO) is one of the most common processes for water desalination. However, this process is limited by high silica and salt concentrations in water. At high concentrations silica clogs the membranes used in the RO process, reducing their life and increasing operational costs. In this study, quaternary ammonium resins and sulfonic acid resins were used to remove silica …

Microstructure And Electrical Performance Of Sputter-Deposited Hafnium Oxide (Hfo2) Thin Films, Brandon Adrian Aguirre

Open Access Theses & Dissertations

Hafnium oxide (HfO2) based dielectrics have been currently considered as the possible replacements for the traditional gate-oxide (SiO2) of the complementary metal-oxide semiconductor (CMOS) devices. The high dielectric constant, wide band gap, and thermal stability in contact with Si make HfO2 a potential material for application in CMOS devices. The performance of HfO2 as a gate oxide material, however, depends on its quality and interface structure with Si. In this work, HfO2 thin films have been deposited by rf sputtering onto Si(100) substrates under varying growth temperatures (Ts). The objective of the work is to understand the growth and microstructure …

High Temperature Oxidation Characteristics Of Nb-10w-Xcr Alloys, Maria Del Pilar Moricca

Open Access Theses & Dissertations

The use of refractory metals in high temperature applications has been attractive for several years. Systems based on niobium represent a potential new generation of refractory materials systems because of their low density, high melting points, and strength at elevated temperatures. Despite these desirable characteristics, the widespread use of niobium-based alloys is limited because its oxidation resistance is still inadequate for structural applications. Understanding the oxidation kinetics of Nb-based alloys and the role of the different phases in the oxidation process is of crucial importance to improve the oxidation resistance of these materials.

The effect of Cr content on the …

Electric Power Distribution Optimization Using Evolutionary Algorithms, Sowmya Parimi

Open Access Theses & Dissertations

In the present research, a new evolutionary algorithm is developed to solve the component allocation problem in electricity distribution systems. The problem addresses the upgrade/design of an electricity distribution system with the objective of minimizing expected system downtime subject to cost and repair time constraints. The algorithm is tested on the Dual Element Spot Network (DESN) configuration which is one of the most commonly used configurations by the power industry. This algorithm is demonstrated with two examples.

Microstructural Characterization Of Overaged Gtd-111 Hp Turbine Buckets, Oscar Quintero

Open Access Theses & Dissertations

Superalloys are metallic materials that exhibit excellent mechanical strength and creep resistance at high temperatures. They have good surface stability and are corrosion resistant. Superalloys are mostly used in the aerospace industry, gas turbine engines and blades (hot zones of gas turbines), and where extreme heat is encountered. The focus of this research was on the GTD-111 Ni-base superalloy, which is a General Electric (GE) proprietary superalloy mostly used in gas turbine blades with the form of high pressure or first stage buckets. This alloys features better mechanical properties, creep resistance, and a higher stress rupture temperature than the commonly …

Optimization Of A Strapdown Inertial Navigation System, Mario Ruiz

Open Access Theses & Dissertations

The focus of this Thesis is to find 21 error parameters in a Strapdown Inertial Navigation System (SINS) that would minimize objective functions or error functions to increase accuracy utilizing an optimization algorithm. The algorithm used is goal attainment by Gembiki which is a multi-objective optimization algorithm proven to outperform other optimization methods in terms of efficiency and accuracy over large numbers of problems. Simulations of a noise-free SINS mounted on an aircraft were done in a stationary and on the move scenario to simulate two conditions in which alignment could become necessary. The error parameters to find were sensor …

Microstructural Characterization And Heat Treatment Of A-286 Turbine Buckets, Christopher Michael Bradley

Open Access Theses & Dissertations

A-286 is an iron-based superalloy used extensively in land-based gas turbines for 2nd stage (low pressure) buckets and 1st and 2nd stage wheels. Although A-286 may appear to some as just another austenitic stainless steel, its elevated temperature properties are attributed to ' precipitate structures, effective distributions of alloy carbides in the forms of M23C6, M6C and MC, and solid solution strengthening. Unfortunately over the course of these components service lives microstructural degradation develops in the form of η-phase formation. The presence of η-phase, especially in large quantities, can have a negative effect on stress rupture properties. Resistance to creep …

Characterization Of A Mems Accelerometer For A Highway Health Monitoring Ultra-Low Power Sensor, Karla Cecilia Enriquez

Open Access Theses & Dissertations

With the 2009 American Recovery and Reinvestment Act, government officials recognized the need to implement automated methods that reduce the cost of assessment projects and provide a long-term solution to monitor the structural health of bridges and highways. Although important research exists in the area of non-destructive evaluation, current road health monitoring efforts continue to be costly and time consuming. This Thesis focuses on the characterization of a MEMS accelerometer intended to be the basis of a novel ultra-low power sensing system to remotely asses the condition of highways. The architecture of a sensor prototype built to validate an algorithm …

Insight Into The Physics Of Rupture: Dynamic Triggering Seismicity, Hector Gonzalez-Huizar

Open Access Theses & Dissertations

Seismic waves can trigger earthquakes and tremor at large distances from the causable event. Dynamic triggering occurs when the surface waves from large earthquakes change the stresses conditions on previously overstressed faults, promoting failure. To understand the causative stresses and environments behind dynamic triggering, we model the change in the stress field that the passing of Rayleigh and Love waves cause on a fault plane of arbitrary orientation relative to the direction of propagation of the waves, and apply a Coulomb failure criterion to calculate the potential of these stress changes to trigger seismicity. We apply our model to three …

Directional Analysis And Filtering For Dust Storm Detection In Noaa-Avhrr Imagery, Swapna Janugani

Open Access Theses & Dissertations

In this research, we propose spatio-spectral processing techniques for the detection of dust storms in 5-band NOAA-AVHRR imagery. The research is mainly focused on locating the dust sources and automatically finding the transport direction of the dust storm. Previous methods that use simple band math analysis have produced promising results but have some drawback in producing consistent results when low SNR images are used. Moreover, in seeking to automate the dust storm detection, the presence of clouds in the vicinity of the dust storm creates a challenge in being able to distinguish these two types of image texture. Our research …

An Investigation On The Mixing Hydrodynamics Of A Gas-Solid Fluidized Bed, Mario Alberto Ruvalcaba

Open Access Theses & Dissertations

In previous decades, the experimental and numerical studies of multiphase flows have remarkably increased especially gas-solid flows. Research of this type has abundant applications in energy, chemical processes, among others. Moreover, common applications include fluid catalytic cracking for petroleum refineries, fluidized bed reactors (type of chemical reactors), interface modification, such as applying a coating onto solid items, and an important technology breakthrough in coal gasification. The work presented on this thesis concentrates on the investigation of gas-solid flows utilizing Computational Fluid Dynamics (CFD) methods. The gas-solid flows studies performed on this investigation assumed the solid phase as a continuum with …

Fabrication And Characterization Of Zirconium Oxide Thin Films, Vemnkata Rama Sesha Ravi Kumar Vemuri

Open Access Theses & Dissertations

Zirconium oxide (ZrO2) is an important material with a potential for a wide range of technological applications. The outstanding chemical stability, electrical and mechanical properties, high dielectric constant, and wide band gap of ZrO2 make it suitable for several industrial applications in the field of optics, electronics, magneto-electronics, and optoelectronics. ZrO2 is frequently used as a high refractive index material in multilayer optical coatings in high power laser systems. ZrO2 is employed in super plastic structural ceramics that demonstrate excellent strength and fracture toughness. ZrO2 has been considered as a promising dielectric to replace SiO2 in advanced metal oxide semiconductor …

Estimating Variation In Stiffness And Volume Change Of Clays From Geochemical And Index Properties, Cynthia Roxanna Zuniga

Open Access Theses & Dissertations

Clayey soils from six different locations in Texas were analyzed and evaluated with respect to their expansion and shrinkage and change in stiffness associated with moisture content variation. These soils consist of five high plasticity-index (PI) clays (PI greater than 25) and one low-PI clay (PI = 17). The behavior of the clays changes dramatically with moisture content fluctuation, thus causing stiffness and volume changes throughout the year. Total or differential volume movements caused by swell or shrinkage strains of expansive soils and reduction in modulus can exert enough pressure to damage the pavements and cause maintenance problems.

The intent …

Remote Control Of Multiple Robots: A Wireless Sensor Network And Virtual Reality Approach, Yingjun Zhu

Open Access Theses & Dissertations

A tele-operation system of robots based on virtual reality and WSN is established and demonstrated. Pro/E, Blender 3D and Python language are adopted to build up and carry out the virtual environment and virtual robot. Wireless Sensor Network (WSN) technology has been used to achieve the tele-operation function. The WSN enables the users to control the robots and collect the data/status from the robots as well. Robot virtual reality software has been developed and presented in the paper. The network setup and the control/communication Application Programming Interface (API) has been shown in this paper.

Asset Management Application Towards An Improved Right Of Way Acquisition, Dora Oralia Francis

Open Access Theses & Dissertations

The purpose of this research is to discover a most suitable approach when the right of way acquisition process begins. As soon as it is known that the right of way acquisitions begin, speculations are made to parcels in order to increase the values of these parcel. Different types of speculations can be made, at a different phase of the right of way (ROW) acquisition process. The parcel cost can vary due to speculations according to the phase of the right of way acquisition process. To help assist the Texas Department of Transportation (TxDOT) on the right of way acquisition …

Comparison Of Older Mexican American Upper Extremity Reach Capabilities To Older Anglo Americans, Odi Mike Ikpe

Open Access Theses & Dissertations

The study aimed to investigate if there are upper extremity reach capability differences in older Mexican Americans and older Anglo Americans. The subjects were recruited and corresponded to the 2000 census track. Upper extremity reach capability was determined by analysis of 20 range of motion variables. A MANOVA analysis utilizing SPSS software was performed with age, gender and ethnicity as independent variables while height and 20 range of motion anthropometric measurements servings as dependent variables (responses). Ethnicity as a function of age was found to be significant in height, horizontal distance from buttock to hand, rotation of head to the …

Experimental Study Of The Response Of Semiconductor Detectors For Edxrf Analysis., Sunil Kumar Valaparla

Open Access Theses & Dissertations

This present work relates to the study and characterization of the response function of an energy-dispersive x-ray spectrometer. The problems of energy, efficiency and resolution calibration of the system operating in the energy (5-60 keV) range are discussed. We present the operation characteristics of the portable pyro-electric x-ray generator (COOL-X) and the application of the calibrated response spectrum in the elemental analysis using X-ray Fluorescence (XRF).

We study the response of the Si(Li)-Pin XR-100CR semiconductor detector to low energy photons. The photopeak efficiency was determined experimentally by using radioisotopes and compared against a theoretical efficiency curve. The efficiency for gamma …

E-Quality Control: A Support Vector Machines Approach, Kalyan Reddy Aleti

Open Access Theses & Dissertations

The web-enabled quality control process presents many benefits to industry, such as universal access, remote control capability, and integration of production equipment into information networks for improved efficiency. This capability has a great potential, since engineers can access and control the equipment anytime, anywhere as the design stages evolve. In this context, this work uses innovative methods in remote part tracking and quality control with the aid of the modern equipment and application of Support Vector machine learning approach to predict the outcome of the quality control process. The classifier equations are built on the data obtained from the experiments …

Evaluation Of An Image Processing Algorithm For Scene Change Detection, Daniel Flores

Open Access Theses & Dissertations

Despite the efforts to reduce traffic accidents by government entities and automobile manufactures, the numbers of accidents are not considerably reduced. An evaluation of an algorithm based on the fly's eye is done on this research applying its principles to detect scene change on images for printed circuit boards providing initial steps to implement this algorithm on vehicular traffic to keep track of objects moving on the field for collision avoidance purposes. The effectiveness of the algorithm is addressed through a comparison of its performance with that found in experimental data.

Analysis Of Number And Mass Concentration Of Coarse And Fine, Nancy Garcia

Open Access Theses & Dissertations

There is currently much concern over particles suspended in the ambient air, their effects on people and the environment throughout the world. The suspended particles can cause adverse health effects, reduce visibility and over the course of time wear buildings. Primary air quality concerns are of particles, their effects and their key characteristics. Particle number concentration (NC) of traffic emissions is an important element of the study, specifically heavy duty diesel engine emissions. Particle number concentration is the number of particles of a specific size in a unit of air; in this study they are measured by the number of …

Stereolithography Of Poly(Ethylene Glycol) Hydrogels With Application In Tissue Engineering As Peripheral Nerve Regeneration Scaffolds, Karina Arcaute

Open Access Theses & Dissertations

In recent years, rapid prototyping (RP) technologies initially developed to create prototypes prior to production for the automotive, aerospace, and other industries, have found applications in tissue engineering (TE). Several different RP technologies are being used to fabricate biocompatible 3D structures with controlled micro- and macro-scale characteristics. The focus of this research was to explore the capabilities of the RP technology, stereolithography (SL), for creating complex, 3D scaffolds with applications in TE using a photocrosslinkable biopolymer, poly(ethylene glycol) (PEG). The primary objective was to create an implantable multi-lumen nerve guidance conduit (NGC) for the regeneration of peripheral nerves.

Studies of …

Allocating Emergency Response Vehicles To Cover Critical Infrastructures, Hao Lei

Open Access Theses & Dissertations

Optimal deployment of limited emergency response service units in a metropolitan area is of interests to public agencies. The limited emergency units not only have to respond to the demand for service by residents and businesses, but also cover Critical Infrastructures (CIs). This Thesis formulates an improved optimization model to allocate different types of Emergency Response Service (ERS) units among their candidate base stations. The allocation of units must ensure maximum coverage to CIs, subject to the capacities of the base stations, service standard in terms of time to reach the CIs, and the availability of the ERS units (when …

Quality Evaluation Of Portland Cement Concrete At Early Age With Free-Free Resonant Column, Gilberto Wenglas

Open Access Theses & Dissertations

At early age, the behavior and mechanical properties of portland cement concrete changes rapidly with time due to hydration. The hydration process consists of a series of chemical reactions that accelerate nonlinearly with the rise in temperature. The hydration process consists of three stages: the dormant period, the setting time, and the hardening time. Timely opening of roads and resumption of constructions depend of the knowledge of these stages. The initial and final setting times are arbitrarily determined by a standard test (ASTM C 403). Although the setting time has been studied for many decades, the new technologies allow making …

Expert System Design Guide For Lower Classification Roads Over High Pi Clays, Yaqi Wanyan

Open Access Theses & Dissertations

This research was focused on low-volume roads over expansive clayey soils in Texas. In spite of the redundant pavement designs recommended and widely used in Texas for roads in high PI clay areas, these pavements often fail prematurely. This failure occurs primarily because of the highly variable properties of the clayey subgrade throughout the year due to moisture fluctuations. The problematic nature of high PI clays, despite the fact that volumetric changes such as heaving are sometime considered in the design, is of concern since they contribute to roughness and longitudinal shrinkage cracking of the road, and as such the …

A Distributed Reconstruction Of Ekg Signals, Gabriel Cordova

Open Access Theses & Dissertations

In this Thesis the parallel computing methodology is applied to an algorithm used in the reconstruction of electrocardiographic (EKG) measurements. The reconstructions are being performed to obtain a better understanding of the source and behavior of the electrical activity that generates the EKG measurements. The contribution of this Thesis is to identify and eliminate inefficiencies present in the current reconstruction algorithm. Additionally, this Thesis reduces the computation times of the EKG reconstruction by applying distributed computing through the use of Remote Procedure Calls (RPC). Lastly, it provides an analysis of the speed-up and efficiency of the distribution implemented using parallel …

Homography Based Multiple Camera Detection Of Camouflaged Targets, Jesus Flores Guerra

Open Access Theses & Dissertations

This Thesis proposes an improvement on segmentation of camouflaged objects by combining information from multiple static cameras with overlapping views onto a common reference plane. Previous camouflage detection work relies on a single camera and focuses on pattern recognition, gray level co-occurrence matrix (GLCM) computation, convexity detection and operations such as connected components or morphology. These methods make real-time implementation computationally expensive. The proposed work diverges from these techniques, taking advantage of the added information from several viewpoints. Background subtraction is performed on each individual camera and then, the segmentation result is transformed onto a common plane using homography. A …

Screening The Phytoremediation Potential Of Native Plants Growing On Mine Tailings In Arizona, Usa, Md Nazmul Haque

Open Access Theses & Dissertations

Mining companies have been playing an important role for the utilization of the Earth's natural resources for the prosperity of human society. However, the mining of resources has generated solid wastes called tailings that have become a serious environmental threat worldwide. Technologies such as soil caping have been used to remediate the problem. Nevertheless, the remediation of mine tailings using conventional technologies is costly and environmentally unpleasant. Since the last few decades, a plant based technology known as phytoremediation has appeared as a promising alternative. Several plant species have demonstrated to have phytoremediation capabilities; though, best results have been obtained …

Phase Change Cooling Applications - Engine Cooling, Kiran Kumar Katta

Open Access Theses & Dissertations

Waste heat recovery system composed of two phase cooling system, exhaust heat exchanger, and mini-turbine has been proposed by Henry Works, Inc to generate auxiliary power via harvesting engine cooling and exhaust heat loss from heavy duty vehicles. The objective of this research is to evaluate the two phase cooling system through the engine dynamometer test and obtain initial test data for the development of the waste heat recovery system. Engine dynamometer experiment for evaluating two phase cooling has been conducted using Perkins diesel engine. During two phase cooling phase, the coolant temperature showed less than 1 °C variation in …