Engineering Commons^™

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 …

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 …

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 …

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 …

Autonomous Vehicle Navigation: A Comparative Study Of Classical Logic And Neural Network Technique, Javier Alejandro Flores

Open Access Theses & Dissertations

Today is an era in which humans need the help of automated machines to facilitate their hectic lives. Over the past few decades, robotics has been one of the most researched areas in the world. One area of this research is obstacle avoidance for autonomous vehicles. In order to avoid an obstacle, the system may include two important characteristics: obstacle detection and avoidance control. In this Thesis a classical logic system and artificial neural network approach is presented. With the help of an Integrated Development Environment, a virtual robot was able to negotiate a maze and avoid obstacles according to …

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 …

Identification Of Human Gait Using Genetic Algorithm Tuned Fuzzy Logic, Abdallah Abdel-Rahman Hassan Mahmoud

Open Access Theses & Dissertations

Data mining is concerned with the discovery of useful hidden information in large databases. Classification is a data mining task producing rules in which a set of attributes in data predict the value of a class attribute. Classifiers usually produce a large number of rules, most of which are not interesting to the user. Rule interestingness is a decisive factor. However, evaluating rule interestingness is challenging as it involves both objective (data-driven) and subjective (user-driven) aspects.

In this research, a fuzzy genetic algorithm is proposed to discover classification rules that are both accurate and interesting. Continuous attributes are fuzzified so …

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 …

Reduced Dimensionality Hyperspectral Classification Using Finite Mixture Models, Vikram Jayaram

Open Access Theses & Dissertations

Classification of HSI data is a challenging problem for two main reasons. First, with limited spatial resolution of HSI sensors and/or the distance of the observed scene, the images invariably contain pixels composed of several materials. It is desirable to resolve the contributions of the constituents from the observed image without relying on high spatial resolution images. Remote sensing cameras have been designed to capture a wide spectral range motivating the use of post-processing techniques to distinguish materials via their spectral signatures. Secondly, available training data for most pattern recognition problems in HSI processing is severely inadequate. Under the framework …

Nondestructive Testing For Finding Out The Displacement Of Crack In Silicon Nitride, Sriharsha Kurra

Open Access Theses & Dissertations

Nondestructive testing (NDT) has become an increasingly vital factor in the effective conduct of research, development, design and manufacturing. Only with the appropriate use of nondestructive testing techniques, the benefits of advanced materials science can be fully realized. NDT has a wide range of industrial applications and various methods and techniques are employed to perform the nondestructive testing. The current work aims to demonstrate the nondestructive testing technique applied to determine the damage in silicon nitride. Ceramics are brittle materials and non destructive evaluation methods are required to assess the quality and reliability of them. A nondestructive evaluation technique has …

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 …

Finite Element Modeling Of Nondestructive Test Methods Used For Detection Of Delamination In Hot Mix Asphalt Pavements, Dante Mejia Munoz

Open Access Theses & Dissertations

For the simulation of detection of delamination this study focus on three NDT methods: Impact Echo, Impulse Response and Ultrasonic Surface Waves. The was evaluated and then a parametric study was elaborated.

Semi-Automated Frame Transformations Using Fft Analysis On 2-D Images, Francisco Javier Osuna

Open Access Theses & Dissertations

Cassini entered Saturn's orbit on July 1, 2004 beginning a four-year exploration of Saturn. In 2008 the mission was extended, and Cassini continues to collect and transmit images and data collected during its mission. In order to accurately interpret images, it is necessary to know the location and orientation of the camera provided the field of view when the image was collected. While the mission managers provide initial estimates of this orientation, scientific analysis requires better estimates than the initial data provided. Navigation is a process for improving the estimation of the true camera pointing vector as determined by features …

Effects Of Build Orientation, Aging, And Pre-Conditioning On Mechanical Properties For Stereolithography-Manufactured Astm Type I Specimens Using A Design Of Experiments Approach, Karina Puebla

Open Access Theses & Dissertations

With industry's growing focus on the rapid manufacturing (RM) of end-use products, rapid prototyping (RP) or layered manufacturing (LM) machines that were originally designed to build prototypes may now be required to build functional end-use products. To successfully accomplish the transition, the available materials utilized in RP must provide the performance required for RM. The specific technology used must also be capable of producing repeatable and reproducible parts in regards to mechanical and dimensional properties.

A design of experiments approach was performed to determine the effects of build orientation, aging, and pre-conditioning on the mechanical properties. To perform the investigations, …

Hybrid Ftth Optical Network Using Incoherent Optical Code Division Multiple Access, Joel Quintana

Open Access Theses & Dissertations

Over the past 20 years there has been extensive research on the application of spread spectrum multiplexing techniques for communications via optical fiber. Optical Code Division Multiplexing (OCDMA) is the technique that has exhibited the most promise as a primary multiplexing vehicle for the transition into all-optical processing of data, and as a supplement to other techniques such as Time Division Multiplexing (TDM) and Wave Division Multiplexing (WDM). OCDMA can be classified into incoherent OCDMA, where coding and detection is done on the basis of optical power, and coherent OCDMA where coding is done on a field amplitude basis. The …

Aluminum Hydride Compunds: A Theoretical And Experimental Spectroscopic Study, Layra E. Reza

Open Access Theses & Dissertations

None

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 …

Optimization Of Flow For Plastic Pbt With 45% Glass And Mineral Fiber Reinforcement In An Injection Over Mold Process Using Taguchi, Cpk And Mold Flow Simulation Software Approaches, Israel Sanchez

Open Access Theses & Dissertations

This Thesis analyze the plastic injection molding parameters in order to identify which parameters significantly affects the flow properties of Polibuthylen Thereptalate with 45% glass/mineral reinforcement, and which levels are the best to use for those parameters. With the purpose of optimizing the plastic flow conditions in an injection mold to obtain parts free from short shots (term used to describe a plastic part that is incomplete due to the poor plastic flow in the mold runners and cavities).

The used approach is Taguchi design of experiments to define which parameters have significant effect on the response variable, and the …

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 …

Computational Modeling Studies Of The Structures And Properties Of Organotin(Iv) And Stannyl-Thioether Systems With Comparisons To X-Ray Crystallography, Michelle R. Stem Joseph

Open Access Theses & Dissertations

Controlling the toxic effects of organotin(IV) compounds involves engineering the structure of the molecules to optimize their properties. Molecular engineering, coupled with improved capabilities to generate reliable computational optimization models (COMs), will enable researchers to have greater success at harnessing the highly specific cytotoxicity of organotins. For example, as the thio_n ligand phenyl groups were replaced with Cl atoms, the S-Sn intramolecularity was strengthened, the bond distance decreased, and the stannyl tetrahedral structure was deformed from its triphenyl conformation. With each substitution, conformation deformations lowered the damaging bioactivity levels of thio_n. Bonding various ligands to organotin(IV) compounds …

Transition Metal Catalysts For Hydrodesulfurization Reactions Applied To Petroleum Industry, Brenda Torres

Open Access Theses & Dissertations

Catalysis plays a fundamental role in petroleum refining and basic petrochemical industries creating new routes in the development of industrial processes. Moreover, catalysis has become indispensable to the solution of environmental pollution problems and therefore on public health. World wide concerns for preservation of the environment has motivated the development of "Green" catalyst based technologies, to achieve a better utilization of petroleum resources and demands for cleaner transportation fuels. These environmental concerns have led to increasingly drastic regulations on sulfur, nitrogen and aromatics content in fuels. Sulfur content in the motor and diesel fuels is continuously reduced by regulations to …

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.

Exploring Poly(Ethylene Glycol) As A Suitable Material For Peripheral Nerve Regeneration Scaffolds Manufactured By Stereolithography, Nubia Zuverza

Open Access Theses & Dissertations

One of the challenges in tissue engineering is to have spatial and temporal control over the biological elements within a scaffold used to guide regeneration for example of transected nerves. Some of the physical and chemical characteristics to regulate include incorporation of bioactive domains and release of chemical signals. This study presents the use of stereolithography (SL) to incorporate localized domains for cell adhesion in addition to include releasable nerve growth factor (NGF) in the process of building poly(ethylene glycol)diacrylate (PEGda) hydrogel scaffolds. Besides providing sites for cell attachment, an ideal nerve guidance conduit (NGC) should be able to release …

Estimating Risk Under Interval Uncertainty: Sequential And Parallel Algorithms, Vladik Kreinovich, Hung T. Nguyen, Songsak Sriboonchitta

Departmental Technical Reports (CS)

In traditional econometrics, the quality of an individual investment -- and of the investment portfolio -- is characterized by its expected return and its risk (variance). For an individual investment or portfolio, we can estimate the future expected return and a future risk by tracing the returns x₁, ..., x_n of this investment (and/or similar investments) over the past years, and computing the statistical characteristics based on these returns. The return (per unit investment) is defined as the selling of the corresponding financial instrument at the ends of, e.g., a one-year period, divided by the buying price …

Mathematical Justification Of Spectral/Covariance Techniques: On The Example Of Arc Detection, Jan Beck, David Nemir, Vladik Kreinovich

Departmental Technical Reports (CS)

Detecting arcing faults is an important but difficult-to-solve practical problem. Many existing methods of arc detection are based upon acquiring a signal that is proportional to current and then making an analysis of the signal's power spectrum (or, equivalently, its covariance function). Since the power spectrum, i.e., the absolute values of the Fourier transform, carries only partial information about the signal, a natural question is: why should we restrict ourselves to the use of this partial information? A related question is caused by the fact that even the most efficient methods still miss some arcing faults and/or lead to false …

Computing With Tensors: Potential Applications Of Physics-Motivated Mathematics To Computer Science, Martine Ceberio, Vladik Kreinovich

Departmental Technical Reports (CS)

In this paper, we explain what are tensors and how tensors can help in computing.

Intelligence Techniques Are Needed To Further Enhance The Advantage Of Groups With Diversity In Problem Solving, Oscar Castillo, Patricia Melin, J. Esteban Gamez, Vladik Kreinovich, Olga Kosheleva

Departmental Technical Reports (CS)

In practice, there are many examples when the diversity in a group enhances the group's ability to solve problems -- and thus, leads to more efficient groups, firms, schools, etc. Several papers, starting with the pioneering research by Scott E. Page from the University of Michigan at Ann Arbor, provide a theoretical justification for this known empirical phenomenon. However, when the general advise of increasing diversity is transformed into simple-to-follow algorithmic rules (like quotas), the result is not always successful. In this paper, we prove that the problem of designing the most efficient group is computationally difficult (NP-hard). Thus, in …

An Aspect-Based Approach To Checking Design Constraints At Run-Time, Yoonsik Cheon, Carmen Avila, Steve Roach, Cuauhtemoc Munoz, Neith Estrada, Valeria Fierro, Jessica Romo

Departmental Technical Reports (CS)

Design decisions and constraints of a software system can be specified precisely using a formal notation such as the Object Constraint Language (OCL). However, they are not executable, and assuring the conformance of an implementation to its design is hard. The inability of expressing design constraints in an implementation and checking them at runtime invites, among others, the problem of design drift and corrosion. We propose runtime checks as a solution to mitigate this problem. The key idea of our approach is to translate design constraints written in a formal notation such as OCL into aspects that, when applied to …

On Chromatic Numbers Of Space-Times: Open Problems, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

No abstract provided.