Engineering Commons^™

Novel Control Technique For Cadmium Sulfide Chemical Bath Deposition Using Real Time Monitoring Of Cadmium Ion Molarity, Rafael Ordonez

Open Access Theses & Dissertations

Cadmium sulfide Chemical-Bath-Deposition parameters are modified to allow, for the first time, real time monitoring of cadmium ion molarity using a commercially available cadmium ion Ion-Selective-Electreode at 60°C. This modification involves alterations to typical deposition parameters that eliminate the formation of cadmium hydroxide and keep cadmium ion molarity above 10-7M. The new or atypical parameters developed are pH values below 8.9 and lower moralities for all chemicals. In order to have complexation of cadmium ion driven mainly by ammonia, parameters that minimized complexation by other chemicals are found. Cadmium acetate concentration below 2mM and ammonium acetate concentration below 10mM minimize …

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 …

Buckling Of Dome Structure With Opening, Under Wind Load, Anup Ramesh Marathe

Open Access Theses & Dissertations

Double layered parabolic dome structure, with opening in roof is analyzed for buckling under wind load. Domes with three different opening sizes are used and external wind load is applied from different directions without changing the position of the opening. Dead load and internal wind pressure is also applied. The dead load and internal wind pressure is kept constant. The internal wind pressure is applied as per the ASCE building requirement that is once in positive direction which is towards the surface and once in negative direction which is away from the surface. The data for this project was sent …

Using The Taguchi Design And The Central Composite Design To Increase The Robustness Of A Process From Its Raw Material Variability, Alvaro Cuevas

Open Access Theses & Dissertations

This research presents an experimental study where four controllable and one noise factor are analyzed using the Taguchi approach and the Central Composite Design (CCD) in order to induce robustness in a process that is being designed to treat residual grease from small restaurants. Three response variables are analyzed separately to establish the parameters conditions to obtain the most robust process output. These suggested conditions are validated conducting confirmation runs that are compared statistically to the predictions from the Taguchi prediction model for the Taguchi approach, and the Response optimizer for the CCD. The accuracy of each method is measured …

Treatment Of Ro Concentrate Using Vsep Technology, Guillermo Guadalupe Delgado

Open Access Theses & Dissertations

The city of El Paso has the largest inland brackish desalination plant in the world. The Kay Bailey Hutchison (KBH) Desalting plant produces 15 million of permeate water every day. Due to the excellent quality of the water, the permeate water is blended with brackish water producing a final volume of 27.5 million gallons of water every day. With an average recovery rate of 80%, the KBH plant produces an average of 3 million gallons of concentrated brackish water that is disposed of via injection wells 23 miles from the plant.

Conventional reverse osmosis (RO) systems are not capable of …

An Experimental Study Of The Hydrodynamics Of Multiphase Flow In Fluidized Beds, Gerardo Vargas

Open Access Theses & Dissertations

Fluidized bed reactors have been widely used as a gasifier in coal gasification processes to convert coal into other forms of energy. At this stage, full fluidization is required to attain the best thermochemical reaction within the fluid-solid mixture. This can only be achieved if the fluid is maintained between minimum fluidization and terminal velocities. To better understand the hydrodynamics of multiphase flow, a fluidized bed was designed and constructed to carry out the investigation. Compressed air and 1-mm glass beads were used to determine gas minimum fluidization and terminal velocities at three different particle concentrations. The solids were enclosed …

Application Of Sensor Fusion To Human Locomotor System, John Kweku Avor

Open Access Theses & Dissertations

This research study proposes a multi-sensor data fusion technique to determine the complex interactions between the sensory, muscular and mechanical components of the human locomotor systems (neuromechanics). The object in this work is to demonstrate the viability in using inertial sensors for accurate gait phase determination and to present the acceleration effect specific body segment contributes in order to establish a functional gait. The current method used in determining gait phases consist of combining ground reaction force and angular data, this method is time consuming and cannot be totally reliable. We found out that gait phases can be determined distinctively …

Spectroscopic Characterizations Of Organic/Inorganic Nanocomposites, Jayesh Rasikalal Govani

Open Access Theses & Dissertations

Inorganic potassium dihydrogen phosphate (KDP) is widely known for its value as a nonlinear optical material. In this study, pure and l-arginine-doped KDP single crystals were grown by the slow solvent evaporation technique and further subjected to infrared absorption and Raman studies for the confirmation of chemical group functionalization and possible bonding between the organic and inorganic materials. The appearance in the infrared absorption spectra of additional vibrational lines, which mostly originate from disturbed N-H, C-H, and C-N bonds of the l-arginine-doped salt, confirm the interaction between KDP and the organic material. This affirmation is supported by more evidence from …

Detection Of Gas/Odor Based On Quartz Crystal Microbalance Sensors And Fuzzy Similarity Measure, Yi-Chen Lo

Open Access Theses & Dissertations

In this research, an array of six Quartz Crystal Microbalance sensors (QCM) using fuzzy similar measurement is proposed to recognize different gases and the percentage of those gases in a mixed gas. The experiment suggests three different gases, oxygen, helium, and argon as test gases and the nitrogen as the reference gas. Six QCMs in this array are coated respectively with six different specific polymers that are selected based on Linear Solvation Energy Relationship (LSER) method, in order to absorb gas molecules so as to recognize responses of resonant frequency changes from QCMs. Testing with different gases results in different …

Assessment Of Super-Resolution For Face Recognition From Very-Low Resoution Images, James Roger Roeder

Open Access Theses & Dissertations

Super-Resolution (SR) involves the registration of multiple images/frames and reconstruction of a single higher resolution image. The goal of this research is to use multiple, very-low resolution images, such as those produced from a video sequence in a wireless sensor network system, as input to the super-resolution process in a face recognition system. The algorithm used for face recognition is the Fisherfaces method with a nearest neighbor classifier used for the recognition decision. Super-resolution consists of two stages, a registration stage and a reconstruction stage.

The testing images were segmented using a simple skin color detection approach. After the cropping, …

An Impedance Model Approach For Adaptive Cruise Control, Xi Sun

Open Access Theses & Dissertations

The objective of this Thesis is to design an intelligent cruise controller for the motion control of a vehicle platoon and discuss the relationship between following distance and signal sampling frequency. For safe vehicle following, an Adaptive cruise control (ACC) law is considered in an impedance model based approach. The impedance model is developed to guide the dynamic behavior of the following vehicles. In order to assure the safety of the vehicle platoon, it is necessary to regulate the distance between vehicles at an appropriate value. The proposed control law uses relative speed and spacing as well as preceding acceleration …

High Temperature Oxidation Behavior Of Nb-20mo-15si-5b-20cr Alloy, Julieta Angelica Ventura

Open Access Theses & Dissertations

Materials for high temperature applications, such as jet engines, gas turbines and turbine blades, require a balanced combination of physical and chemical properties to withstand the aggressive environments in which they are utilized. Some of the properties required are high strength, low density, high melting point and good oxidation resistance at elevated temperatures [1-3]. For this reason, the microstructure and oxidation behavior of the Nb-20Mo-15Si-5B-20Cr alloy (at.%) has been studied as a potential candidate to replace Nickel-based alloys currently used in the aerospace industry.

Short term oxidation (STO) and long term oxidation (LTO) studies have been performed in air for …

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.

Observed Superspin-Glass Behavior In Ni0.5zn0.5fe2o4 Nanoparticles, Antony Adair

Open Access Theses & Dissertations

In this investigation we seek to identify the magnetic behavior of Ni0.5Zn0.5Fe2O4 nanoparticles though AC-susceptibility and DC-magnetization measurements. Powder x-ray diffraction was performed to determine the purity and average diameter ( ~ 9nm) of the particles. Aditionally, structure was confirmed by comparison through the International Centre for Diffraction Data's Powder Diffraction File [52] (PDF # 08-0234).

Zero-field cooled and field cooled DC magnetization measurements (bifurcation and blocking temperature), as well as M(H) hysteresis (below and above the blocking temperature) lead us to initially suggest that the material may in fact be superparamagnetic. However, further investigation of the real AC susceptibility …

Verification Of Nyslab A Software For The Analysis Of Jointed Pavements, Maryam Limouee

Open Access Theses & Dissertations

A significant amount of research and development has been conducted for decades to provide a tool for the design and analysis of jointed slabs on different types of foundations. ILLI-SLAB, JSLAB, EverFE and ISLAB are the most used finite element modeling (FEM) codes that have gone through several iterations of improvement. JSLAB has been maintained by the Federal Highway Administration (FHWA) and is distributed free of charge and there is significant interest in further improving the capabilities of that software package.

Researchers at the University of Texas at El Paso have been charged to implement several modifications in the latest …

Characterization And Cytotoxic Assessment Of Ballistic Aerosolized Particulates For Tungsten Alloy Penetrators Interacting With Steel Targets, Brenda Ivette Machado

Open Access Theses & Dissertations

The aerosolized particulates produced during an impact of depleted uranium munitions can potentially contaminate extensive areas around the impact sites and cause a wide spectrum of civilian and military damage. Thus materials such as WHA have been prompted for consideration. The present research is concerned with the regular collection of aerosol particulates associated with ballistic WHA rod penetration into rolled homogeneous steel (RHA) or other related steel armor as armor plate sequences. Particulate size characterization via scanning electron microscopy (SEM) and transmission electron microscopy (TEM) along with chemical compositions via energy dispersive spectroscopy (EDS) were the focus of this 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 …

Flashback Propensity Of Gas Mixtures, Bidhan Kumar Dam

Open Access Theses & Dissertations

In this study, experimental measurements of flashback propensity of hydrogen (H2)-carbon monoxide (CO) mixtures, which are the primary constituents of syngas fuels, are described. The effects of H2 concentration, diluents and swirl on the flashback propensity of H2 CO flames are discussed. For boundary layer type flashback, the critical velocity gradient (gF) values of 5 to 95%, 15 to 85%, and 25 to 75% H2-CO mixtures somewhat agree with the scaling relation (g_F=c (S_L^2)/α) and yield an average c value of 0.038. At a lower SL2/α ratio, burner diameters have small effects on critical velocity gradient measurements; however, the effect …

Additive Layer Manufacturing Of Ti-6al-4v By Electron Beam Melting From Powder Particles: Solid, Mesh And Foam Components Study, Sara M. Gaytan

Open Access Theses & Dissertations

Additive Manufacturing by Electron Beam Melting Rapid Manufacturing is a technology that consists of the fabrication of a CAD design by melting powder particles in a layer by layer fashion. In this study, Ti-6Al-4V has been utilized to fabricate solid, mesh and foam components by EBM technologies. Powder analysis of Ti-6Al-4V was performed to obtain a better understanding of the porosity obtained by the system. After proper optimization of the machine, and porosity control, microstructural analysis was performed to the components already mentioned and correlated by transmission electron microscopy. Besides the microstructural analysis, tensile and hardness testing was performed to …

An Integrated Software Package For Model-Based Neuro-Fuzzy Classification Of Small Airway Dysfunction, Nazila Hafezi

Open Access Theses & Dissertations

Respiratory disorders can be difficult to differentiate, as their symptoms are sometimes similar to one another. Concerning asthma which is the major interest in this research, early detection of small airway impairment could greatly help with timely diagnosis. In this research, an integrated software package (ISP) has been developed to help clinicians in classification of asthma severities using Impulse Oscillation data.

The ISP has been developed based on object-oriented methodology. In this package, IOS "diagnostic" parameters such as AX and frequency-dependence of resistance as well as parameter estimates of extended RIC (eRIC) and augmented RIC (aRIC) models (simplified cases of …

Retention And Productivity In Industrial Search And Scan Tasks, Camilo Aguilera

Open Access Theses & Dissertations

An experiment was developed in order to study the interaction between individual factors (gender and mood) and the retention ability in search and scan activities. 54 subjects between 18 and 30 years old participated in a computer-based memory test from the North of Mexico area. A full factorial design was used to analyze the variables. Two factors, one with two levels (gender: male and female), and the second factor with three levels (mood: positive, neutral, and negative) were used in the analysis. The output was measured as the amount of characters memorized in a string of random alphanumeric characters. Data …

Failure Analysis And Materials Characterization Of Hip Implants, Amanda Marie Bastidos

Open Access Theses & Dissertations

This research focused on the microstructural characterization and failure analysis of hip implant components. The main hip components analyzed were the femoral heads and the ultra-high molecular weight polyethylene (UHMWPE) liners. Previous research has shown that hip implants tend to fail by the PE liners due to adhesive and abrasive wear, delamination, and third body particles (metals, ceramics, and PE). The methods and procedures for analyzing the said failures consisted of non-destructive and destructive evaluations. Non-destructive evaluations included of techniques such as visual characterization and dye penetrant inspection (DPI)-which displayed macroscopic surface details and presented initial clues as to the …

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 …

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 …

Design Of A Low Voltage Analog To Digital Converter, Praveen Kumar Palakurthi

Open Access Theses & Dissertations

For the past 40 years, the number of transistors per chip has been increasing at an exponential rate confirming Moore's Law regarding the growth of chip complexity. Increases in transistor count have led to enhancements in functionality and made possible products with features that were unimaginable ten years ago. Consequently, the resulting increase in digitization in all electronics, across a wide range of applications, requires the Analog-to-Digital Converters (ADCs) with a higher resolution and lower power consumption. The evolution of the integrated circuit technologies and scaling methodologies partially helps in providing faster circuits and allowing complex functionalities in a given …

Discrete Element Modelling Of Silicon Nitride Ceramics: Crack Formation And Propagation In Indentation Test And Four Point Bending Test, Rajeev Senapati

Open Access Theses & Dissertations

Advanced ceramic materials have been extensively used in aerospace, automobile and other industries. However, the reliability of the advanced ceramics is the major concern because of the brittle nature of the materials. This work aims to model silicon nitride ceramics using Discrete Element Method (DEM) and simulating the crack formation and propagation. DEM software package PFC2D is used to simulate indentation test and four point bending test on silicon nitride ceramics and the behaviour of crack formation and propagation is identified. The numerical representation of ceramic materials is done by generating a densely packed particle system using the specimen genesis …

Integrated Finite Element Analysis Program To Evaluate Pavement Performance And Predict Non-Destructive Testing Response, Cesar Tirado

Open Access Theses & Dissertations

The response of a pavement system under wheel loading has been a subject of research for many decades. Several models have been developed to predict pavement performance based on layer deformation and fatigue cracking. Among them stand out computer programs based on linear elasto-static layered systems and viscoelastic-plastic models; however, newer or more advanced constitutive models cannot be rigorously incorporated into them. In contrast, finite element techniques allow incorporation of nonlinear and viscoelastic-plastic behavior of the pavement materials but licensing of software and the need to train personnel greatly limits its use by highway agencies. A mechanistic-empirical (M-E) approach for …

Retrofitting A Stereolithography System Within A Laminar Flow Hood, Mahesh Pandurang Tonde

Open Access Theses & Dissertations

This research focused on retrofitting the stereolithography (SL), a rapid prototyping technology, inside a laminar flow hood to provide an aseptic, particulate-free environment for scaffold fabrication. Two of the important objectives of this project were to retrofit the commercial SLA 250/30 inside a laminar flow hood to demonstrate that the manufacturability of the Bio-SL system was comparable to original SLA 250 system and to conduct the sterility test on fabricated scaffolds to show that the laminar flow hood was able to provide an aseptic, particulate-free environment for the fabrication.

Vision-Based Virtual Mouse System, Tom Wanjala Watiti

Open Access Theses & Dissertations

This thesis describes a virtual mouse system that utilizes machine vision technology to enable a user to navigate through software window screens on a standard personal computer, access and control software, and/or peripheral devices attached to the personal computer. Utilizing the virtual mouse, the user can execute the standard control functions of the system mouse required to perform software application selection functions and navigation tasks without physical interface with the controlled computer. The machine vision algorithm utilizes a set of four simulated photoelectric sensors, with Gaussian filter sensitivities, to compute and track the mouse location. By utilizing Gaussian filters, instead …

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 …