Engineering Commons^™

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 …

Multi-Objective Network Reliability Optimization Using Evolutionary Algorithms, Franciso Oswaldo Aguirre

Open Access Theses & Dissertations

This work presents a new multiple objective evolutionary algorithm to solve three well known network reliability allocation problems considering different conflicting objectives to be optimized simultaneously. The new algorithm is applied in the design of a telecommunication network that is formed for several stations or nodes interconnected by telecommunication links or paths. The problem presented in this work involves finding which links to activate in order to obtain connectivity in the nodes. The number of nodes that need to be connected depends of the case that is being evaluated. The three network reliability problems considered are: all-terminal, k-terminal, and two-terminal. …

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 …

Effect Of Air Addition On Plasma-Based Reforming Of Methane And Propane, Atul Vitthalrao Ambhore

Open Access Theses & Dissertations

No abstract provided.

Laminar Burning Velocities Of Gas Mixtures, Vishwanath Reddy Ardha

Open Access Theses & Dissertations

In this study, burning velocities of hydrogen-carbon monoxide (H2-CO) mixtures, which are primary constituents of syngas fuels, are measured. The effect of different burner systems, H2 concentration, and different measurement techniques on the burning velocities of H2-CO mixtures is also discussed. The burning velocities of H2-CO mixtures increase with the increase in H2 content in the mixture. When compared with different burner systems using different methods, the burning velocity data almost coincide in the lean condition, but at rich condition the data stray away from each other. The burning velocities of actual syngas compositions (based on different sources of coal) …

Art In A New Light: Design And Assessment Of Illuminants To Reduce Photochemical Degradation Of Works Of Art, Monica Fabiola Delgado

Open Access Theses & Dissertations

The purpose of this research is to design the best lighting that will minimize long term photochemical degradation of Old Master Drawings and/or other works of art, while maintaining the patron's appreciation of the object's color and detail. The present approach is a technological refinement to the basic underlying earlier work on fluorescent lighting by W. A. Thornton, W.A. at General Electric1. Thin-film dielectric, multi-coating technology is used to create filters that eliminate ultraviolet light, near infrared light and significant unnecessary parts from the visible spectrum, thus maximizing the reduction in photochemical degradation, while maintaining optimal color rendering. Three interference …

Hybrid Approach For Site Selection Using Impact Assessment And Principal Component Analysis, Ugandhar Reddy Kondamadugula

Open Access Theses & Dissertations

Principle component analysis (PCA) is used to analyze week data of emission of particulate material from the Residential community. In this Thesis we selected five sites maps where sensors are arranged to collect particulate materials PM0.25, PM 10.Impact Assessment on the site areas are done in the first case,the results Impact Assessment on the site shows that the Global warming potential is really high at the site when the analysis is run for hundred years the Global warming potential has a very high impact on Environment leading to various health hazards. Secondly Principal Component Analysis is used to find out …

Assessing Repeatability Of Four-Point Bending Method For Estimating Fatigue Cracking Of Hot Mix Asphalt, Sara -. Montazeri

Open Access Theses & Dissertations

The objective of this thesis was to assess the repeatability of four-point bending method for estimating fatigue cracking of hot mix asphalt. This experimental research examined the influence of mix proportions, specifically asphalt and air void contents, on fatigue behavior of asphalt beam specimens in the laboratory tested with four-point bending method of loading. Following the relevant specifications, the strain-controlled mode of loading was selected. Fatigue failure is expected to occur at the cycle which the flexural stiffness of asphalt specimen reduced to 50% of initial amount. Up to a 1,000,000 cycles of loading were applied to each specimen.

Different …

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 …

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 …

Multiple Objective Optimization Of Performance Based Logistics, Delia Villanueva

Open Access Theses & Dissertations

This thesis presents a new Performance Based Logistics optimization model. Performance Based Logistics (PBL) is becoming increasingly important for manufacturers in mission critical environments that need to provide ultimate product availability at the lowest cost and with the highest level of customer satisfaction. The U.S. Department of Defense has mandated that Performance Based Logistics programs be adopted by its major weapon systems and equipment suppliers, is one of the newest support strategies to improve the weapon system readiness. This work presents a new multiple objective evolutionary approach that simultaneously optimizes objectives such as Reliability, Maintainability and Total Cost for Ownership. …

Methodology To Develop A Minimum Cost Acceptance Sampling Plan For Highway Construction, Gandhar Wazalwar

Open Access Theses & Dissertations

Quality Assurance has always been a part of manufacturing processes. Since World War II, Acceptance Sampling has been introduced and implemented for quality control and improvement. Since statistical methods are applied for quality assurance, especially in acceptance sampling, various methods are becoming popular among the highway agencies over the period of time. As a result, several specifications have been designed to date based upon different statistical theories, each with its own advantages and shortcomings. Acceptance is a form of quality assurance which is employed as an audit tool for decision making to accept or reject the product based on its …

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 …

Stochastic Gaussian And Non-Gaussian Signal Modeling, Madhu Kishore Yerramothu

Open Access Theses & Dissertations

This thesis introduces a methodology for modeling stochastic signals that have either Gaussian or approximately bell-shaped non-Gaussian distribution. The synthesized model can be used to generate stochastic signals that approximate both the power spectral density (PSD) and the probability density function (pdf) of the original stochastic signal. The new methodology is based on non-linear transformations, filter banks and autoregressive-moving average (ARMA) models. Because the stochastic signals modeled can have Gaussian distribution or approximately bell shaped non-Gaussian distribution, normality tests such as sample skewness, sample kurtosis, Kolmogorov-Smirnov test, and Shapiro-Wilk test are also used.

Many methods have been proposed in the …

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 …

A Study Of The Interaction Of Thioindigo Dye, With Several Inorganic Host Materials, Alejandra Ramirez

Open Access Theses & Dissertations

Maya Blue has been the focus of numerous studies and is believed to be a mixture of palygorskite clay and indigo dye.^1,2 Several derivatives of this pigment have been developed with intriguing properties. For instance, the dye thioindigo reacts with the palygorskite clay to exhibit a broad range of colors from red to blue under UV-Vis excitation. Based on FT-Raman and computer simulation, previous work performed in our group could relate indigo and thioindigo interaction to the aluminum sites in the framework. super>3,4

The work performed with other inorganic host materials such as, layer structures and zeolites have …

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 …

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 …

Guidelines For Using Local Material For Roadway Base And Subbase, Biraj Gautam

Open Access Theses & Dissertations

Flexible base materials that meet TxDOT specifications are getting more difficult to purchase in many TxDOT Districts. As a result, higher quality materials have to be hauled long distances, sometimes from other States. This act would significantly increase the costs associated with the construction of roads and subsequent maintenance and rehabilitation of them. Lower quality (i.e., out-of-specification) materials are normally available. If through appropriate modifications of the materials (adjusting the gradation or/and stabilization) or structural design (specifying thicker layers of base and/or hot mix) the use of the local materials can be permitted, the construction can be accelerated and significant …

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 …

Quantifying Anisotropy In Asphalt Concrete Pavements Using An Ultrasonic Method, Monica C. Jurado

Open Access Theses & Dissertations

Asphalt concrete is a bonded granular material whose internal structure is anisotropic. Such anisotropy is due to anisotropic particles and void's structure, particle distribution and orientation, and restrain and force pattern used during compaction. Even with this knowledge asphalt concrete design is made considering asphalt concrete as an isotropic material. The biggest difference between an isotropic and anisotropic material is that, an isotropic material is characterized by two independent constants and an anisotropic material could be characterized by up to 81 constants. An extensive research to characterize and quantify anisotropy is only available for some composite materials. Based on the …

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 …

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 …

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 …

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 …

Assessment Of Human Muscle Fatigue From Surface Emg Signals Recorded During Isometric Voluntary Contractions By Using A Cosine Modulated Filter Bank, Cristhian Mauricio Potes

Open Access Theses & Dissertations

Human muscle fatigue involves both a decrease in the frequency and increase in the amplitude of a surface electromyographic (EMG) signal. Muscle fatigue is also related to a decrease of the force impeding to reach the same initial level of the maximum voluntary contraction (MVC). To determine muscle fatigue indices, a method is proposed by decomposing a surface EMG signal into 32-subbands. This decomposition was attained by using a cosine modulated filter bank. The

surface EMG signals analyzed during this research were recorded during isometric voluntary contractions. Both the instantaneous mean frequency (IMF) and the instantaneous amplitude (IA) are estimated …

Zinc Telluride Deposition Using Close Space Sublimation, Luis Carlos Romo

Open Access Theses & Dissertations

This thesis presents the optimization process of the close space sublimation (CSS) technique to deposit zinc telluride (ZnTe) on thin-film cadmium telluride (CdTe) solar cells. Previous research has demonstrated that creating a heavily doped ZnTe intermediate layer between the absorber-CdTe and the back contacts produces low-resistive CdTe contacts that overcome the Schottky barrier created at the interface of a metal and a semiconductor [11]. ZnTe interlayer forms a tunnel barrier at the contact interface so the positive charges created at the p-CdTe/n-cadmium sulfide (CdS) junction can be easily collected at the back contact maximizing the current collection process. However, ZnTe …