Engineering Commons^™

Structure And Electronic Properties Of Pure And Nitrogen Doped Nanocrystalline Tungsten Oxide Thin Films, Vemnkata Rama Sesha Ravi Kumar Vemuri

Open Access Theses & Dissertations

Tungsten oxide (WO₃) is a multifunctional material which has applications in electronics, sensors, optoelectronics, and energy-related technologies. Recently, electronic structure modification of WO₃ to design novel photocatalysts has garnered significant attention. However, a fundamental understanding of nitrogen induced changes in the structure, morphology, surface/interface chemistry, and electronic properties of WO₃ is a prerequisite to producing materials with the desired functionality and performance. Also, understanding the effect of thermodynamic and processing variables is highly desirable in order to derive the structure-property relationships in the W-O/W-O-N material system. The present work was, therefore, focused on studying the effects …

An Approach To Power Efficiency Determination In The Solar Energy Systems Using Central Composite Design And Box-Behnken Design, Juan Venegas Mendez

Open Access Theses & Dissertations

We are living in an industrialized world that relies on fossil fuels. The ways, in which these fossil fuels have damaged the earth, in special the environment is worth of special attention and corrective actions. In our days, the climate change (global warming) it is becoming the number one topic. These changes are affecting our health, comfort and our way of living. Solar systems have been working among us since several years, but the truth is that most of us really don't understand how they work and more important, how they work in time in different conditions. Solar panels are …

Development Of Advanced Polymer Nanocomposite Capacitors, Md Rajib

Open Access Theses & Dissertations

With the development of modern technology, the demand of high energy density dielectric capacitor devices is increasing for its significant role in stationary power systems, mobile devices, and pulse power applications. Among the different energy storage devices, polymer film based dielectric capacitor is still one of the most widely used energy storage devices mainly due to its high energy density, significant higher charge/discharge rate and low cost. To further enhance the energy density, high dielectric ceramic inclusions have been embedded in the polymer matrix; however, the temperature influence on the energy density has not been investigated. Therefore, in this research …

Prediction Of Foreign Object Debris/Damage Fod Type Based In Human Factors For Aeronautics Using Logistic Regression Model, David Ricardo Romo

Open Access Theses & Dissertations

Foreign Object Debris/Damage (FOD) has been an issue for military and commercial aircraft manufacturers since the early ages of aviation and aerospace. Currently, aerospace is growing rapidly and the chances of FOD presence are growing as well. One of the principal causes in manufacturing is the human error. The cost associated with human error in commercial and military aircrafts is approximately accountable for 4 billion dollars per year. This problem is currently addressed with prevention programs, elimination techniques, and designation of FOD areas, controlled access, restrictions of personal items entering designated areas, tool accountability, and the use of technology such …

Solving Logistic System Design Problem Considering Various Biomass Feedstock Using Two Metaheuristic Optimization Methods, Jesusita Ibarra

Open Access Theses & Dissertations

Bioenergy has become an important source of energy; it can be used as an alternative to fossil fuel energy, and it offers significant potential to alleviate climate change by reducing greenhouse gas emissions caused by the burning of fossil fuels. The Energy Independence and Security Act decrees the use of 21 billion gallons of advanced biofuel including 16 billion gallons of cellulosic biofuels by the year 2022. It is easy to observe that biomass can make a considerable contribution meet the energy demands. On the other hand, the supply of sustainable energy is one of the main challenges that must …

A Quantitative Approach Using An Axiomatic Design Framework To A Medication Distribution System, Pepito Raguini

Open Access Theses & Dissertations

As the need to minimize medication errors drives many medical facilities to come up with robust solutions to the most common error that affects patient's safety, these hospitals would be wise to put a concerted effort into finding methodologies that can facilitate an optimized medical distribution system. If the hospitals' upper management is looking for an optimization method that is an ideal fit, it is just as important that the right tool be selected for the application at hand. In the present work, we propose the application of Axiomatic Design (AD), which is a process that focuses on the generation …

Purification Of Sodium Sulfate By Crystallization, Perla Teresita Torres

Open Access Theses & Dissertations

Sodium sulfate can be recovered from a dilute solution by concentrating it by conventional water treatment techniques like reverse osmosis and electrodialysis; however, those processes also concentrate impurities like arsenic. The sodium sulfate would have commercial use if it can be recovered in an arsenic-free form. This study demonstrated that sodium sulfate could be separated from impurities using slow cooling crystallization in a novel apparatus developed and designed during the experimentation. This device is called a heat exchanger crystallizer and allows slow cooling crystallization in order to grow pure crystals of sodium sulfate decahydrate. Crystals grown in the heat exchanger …

Investigation Into The Operation And Safety Of Freeway Auxiliary Lanes: Towards Uniform Design Guidelines, Yubian Wang

Open Access Theses & Dissertations

Freeways operate closest to the purest form of uninterrupted traffic flow. There is no constant interruption to traffic flow (such as stop sign and traffic signal), and access is limited to ramp locations. Therefore, at freeways, bottlenecks, if exist, are usually caused by merging and diverging traffic at ramp locations. Bottleneck removal at freeway ramp areas can reduce average freeway commuter delay. Currently, engineers may add auxiliary lanes at ramp areas to mitigate or remove bottlenecks.

The American Association of State Highway Transportation Officials (AASHTO) publication A Policy on Geometric Design of Highways and Streets, commonly known as the "Green …

Reducing Metal Alloy Powder Costs For Use In Powder Bed Fusion Additive Manufacturing: Improving The Economics For Production, Fransisco Medina

Open Access Theses & Dissertations

Titanium and its associated alloys have been used in industry for over 50 years and have become more popular in the recent decades. Titanium has been most successful in areas where the high strength to weight ratio provides an advantage over aluminum and steels. Other advantages of titanium include biocompatibility and corrosion resistance. Electron Beam Melting (EBM) is an additive manufacturing (AM) technology that has been successfully applied in the manufacturing of titanium components for the aerospace and medical industry with equivalent or better mechanical properties as parts fabricated via more traditional casting and machining methods. As the demand for …

Crystal Structure, Phase, And Optical Properties Of Yttrium-Doped Hafnium Oxide Nanocrystalline Thin Films, Alejandro Ortega

Open Access Theses & Dissertations

Yttrium-doped hafnium oxide (YDH) nanocrystalline films were produced by sputter-deposition at various substrate times and temperatures, to produce YDH films in a wide range of thicknesses, dYDH∼25 to 1100 nm. The deposition was made onto optical grade quartz and sapphire substrates. Samples deposited on sapphire were subject to post-deposition annealing (PDA) at various times (3-24 hr) and temperatures (1100 - 1500 °C). The effect of d[special characters omitted]YDH on the crystal structure, surface/interface morphology and optical properties of YDH films was investigated. X-ray diffraction analyses revealed the formation of monoclinic phase for relatively thin films (<150nm). The evolution towards stabilized cubic phase with increasing dYDH [special characters omitted]is observed. The scanning electron microscopy results indicate the dense, columnar structure of YDH films as a function of dYDH. Spectrophotometry analyses indicate that the grown YDH films are transparent and exhibit interference fringes. The band gap was found to be ∼ 5.60 eV for monoclinic YDH films while distinct separation and an increase in band gap to 6.03 eV is evident with increasing dYDH and formation cubic YDH films. The PDA films band gaps were found to be between 5.31 and 5.72 eV, all of which exhibit secondary gaps. A correlation between growth conditions, annealing, phase evolution, and optical properties of the YDH nanocrystalline thin films is established.

The Standardization Of Printable Materials And Direct-Write Systems, Jessica Lynn Porras

Open Access Theses & Dissertations

The standardization of Printable Materials and Direct-Write Systems addresses the many areas of Printing Nano Engineering that lack standards. Printing Nano Engineering is a new method of manufacturing electronics that utilize direct-write system with printing principles to manufacture electronic components.

Standards need to be developed for the different direct-write systems and printable materials in order to provide compatibility amongst printed electronics and to allow the optimization for direct-writ s e systems, and printable materials associated with these systems. There are many different types of direct-write systems in industry; each system involves different methods for printing that incorporates the limiting parameters …

Comparative Characterization Of Ni-Base Superalloys Fabricated By Laser And Electron Beam Melting Technologies, Krista Amato

Open Access Theses & Dissertations

Nickel-base superalloys have been used in cast and wrought, and powder metallurgy forms for nearly four decades for industrial and automotive applications. One drawback of cast alloys is that upon solidification, there is minimal microstructural control. Another issue to be improved is to eliminate the limitations of shapes and forms of fabricated alloys.

Rapid prototyping is a new technology of additive manufacturing that shows to be promising for the freeform fabrication of novel superalloys, including nickel-base alloys. New rapid manufacturing technologies allow us to produce parts in any shape that can be designed by computer-aided design (CAD) software. Additionally, the …

Determinants Of Neighborhood Exposure To Extreme Heat: A Spatial Examination Of El Paso And Juárez, 2010, Faraj Mohamad Aboargob

Open Access Theses & Dissertations

Numerous studies have been conducted on the modification of local weather by the urban environment. In studying urban environmental effects on the urban heat island (UHI), researchers have investigated influences such as land use, vegetation density, topography, population density, and neighborhood socioeconomic status. Many studies have used data collected from field observations, while other studies relied solely on computer modeling. This Dissertation research used a spatial analysis approach, which has been less widely employed, to investigate neighborhood level biophysical, built environmental and socio-demographic determinants of the El Paso and Juárez UHI. The research utilized inexpensive data obtained from US and …

Integration Of Memristors With Mems For Dynamic Displacement Control, Sergio Fabian Almeida Loya

Open Access Theses & Dissertations

In recent years the demand for high-speed, lower power consumption and large-capacity non-volatile memories has increased. Promisingly the memristor can be used due to its special characteristic of having memory through resistance change. The memristor behavior is not limited to digital applications but it can be used in analog application as well including: memristors in chaotic circuits, amoeba's learning, neural synaptic emulation, reprogrammable and reconfigurable circuits, and for neuromorphic computers. On the other hand Micro Electro Mechanical Systems (MEMS) are small scale structures that can interact with the physical world due to their mechanical properties. These devices are widely used …

Preparation Of Cobalt/Nickel Molybdenum Sulfide Catalysts Supported By Aqueous Media Soluble Multi-Wall Carbon Nanotubes., Hassan Ahmad Bleibel

Open Access Theses & Dissertations

Multi-walled carbon nanotubes (MWCNTs) have been subjected to chemical treatment in order to introduce hydrophilic functional groups on their surfaces. These covalently bonded groups did enhance the solubility of MWCNTs in aqueous media as expected. Functionalized MWCNTs were characterized using FTIR, Raman spectroscopy, TGA, X-ray diffraction, dispersion test and TEM. Then, functionalized MWCNTs were incorporated in the hydrothermal synthesis method of transition metal sulfide catalysts (CoMo, NiMo, and Ethylenediamine-CoMo Sulfides). Catalysts were characterized using X-ray diffraction, TEM, SEM, N2 Gas adsorption-desorption, elemental analysis, and Hydrodesulfurization (HDS) reaction of dibenzothiophene (DBT). The objective was to study the functionalized MWCNTs' effect; being …

Post-Pareto Optimality Methods For The Analysis Of Large Pareto Sets In Multi-Objective Optimization, Victor Manuel Carrillo

Open Access Theses & Dissertations

Multiple objective optimization involves the simultaneous optimization of more than one, possibly conflicting, objectives. Multiple objective optimization problems arise in a variety of real-world applications. In general, the main difference between single and multi-objective optimization is that in multi-objective optimization there is usually no single optimal solution, but a set of equally good alternatives with different trade-offs, also known as Pareto-optimal solutions. There are two general approaches to solve multiple objective optimization problems: mathematical methods and meta-heuristic methods. The first approach involves the aggregation of the attributes into a linear combination of the objective functions, also known as scalarization. The …

Development Of A New Genetic Algorithm To Solve The Feedstock Scheduling Problem In An Anaerobic Digester, Ana Cram

Open Access Theses & Dissertations

Genetic Algorithm

Scheduling

Anaerobic digester

An Evaluation Of The Cerro Process As An Efficient Ro Concentrate Management System, Guillermo Guadalupe Delgado

Open Access Theses & Dissertations

The Concentrate Enhanced Recovery Reverse Osmosis (CERRO) Process is a new method to treat RO concentrate and brackish water with high concentrations of silica and calcium sulfate. Prior investigations have shown that the CERRO process can treat this kind of water without fouling or scaling the membranes, but the main factors that allow the system to operate in such conditions were not studied. The research presented here is an evaluation of the CERRO process as an efficient RO concentrate management system. The parameters of operation of the system were evaluated and improved. The precipitation of calcium sulfate was identified as …

Prediction Of Foreign Object Debris/Damage (Fod) Type For Elimination In The Aeronautics Manufacturing Environment Through Logistic Regression Model, Natalia V. Espino

Open Access Theses & Dissertations

Foreign Object Debris/Damage (FOD) is a costly and high-risk problem that aeronautics industries such as Boeing, Lockheed Martin, among others are facing at their production lines every day. They spend an average of $350 thousand dollars per year fixing FOD problems. FOD can put pilots, passengers and other crews' lives into high-risk. FOD refers to any type of foreign object, particle, debris or agent in the manufacturing environment, which could contaminate/damage the product or otherwise undermine quality control standards. FOD can be in the form of any of the following categories: panstock, manufacturing debris, tools/shop aids, consumables and trash. Although …

Urban Impact Of Dissolved Metals In The Paso Del Norte Segment Of The Rio Grande, Sumayeh Ahmad Freiwan

Open Access Theses & Dissertations

The Paso del Norte segment of the Rio Grande experiences two seasons per year; the (wet) irrigation season and the (dry) non-irrigation season. The goal of this study was to improve the understanding of occurrence and contribution of dissolved metals in this region during the non-irrigation season. The objectives of this study were to (1) evaluate the impact of anthropogenic sources of metals on the Rio Grande water quality during the non-irrigation season, and (2) estimate the metal loads carried by the flow to the downstream region of El Paso. In order to evaluate the surface water quality of the …

Optimization Of Bioprinting Process Using Design Of Experiments (Doe) And Taguchi Method, Maria Veronica Gonzalez

Open Access Theses & Dissertations

At this time there is a need for new fabrication techniques for engineering complex biological structures related to regenerative medicine, in vitro tissue analysis, and pharmaceutical testing with the purpose of placing specific cells in specific target locations. Right now, there is no enough conventional cell seeding methods that can achieve it. In order to achieve it, bio-fabrication, which is a delivery mechanism capable of placing biomaterials, cells, and bioactive macromolecules in specific target locations, comes to play an important role in this area. Among different approaches, bioprinting is one of the most useful processes that use drop-on-demand delivery mechanisms …

Reduction Of Onu Buffering For Pon/Vdsl Hybrid Access Networks, Elliott Ivan Gurrola

Open Access Theses & Dissertations

Today's growing internet traffic requires service providers to offer customers faster transmission rates. To keep up with such high transmission rates, service providers need to deploy fiber optical networks. However, due to the high cost involved in deploying the fiber media, this may not prove to be a feasible solution. Instead, service providers can deploy fiber media up to a distribution point, such as a customer's block, and continue the last few hundred feet using the already deployed legacy copper wire media.

In our study we investigate downstream/upstream transmission coordination for passive optical network (PON) / Digital Subscriber Line (DSL) …

Development Of `Lick And Stick' Passive Wireless Temperature Sensor For Harsh Environment, Hasanul Karim

Open Access Theses & Dissertations

Wireless passive temperature sensors have been receiving increasing attention due to the ever-growing need of higher energy efficient and precise monitoring of temperatures in high temperature energy conversion systems such as gas turbines and coal-based power plants. Unfortunately, the harsh environment such as high temperature and corrosive atmosphere present in these systems has significantly limited the reliability and increased the cost of current solutions. Therefore, this research project presents the concept and design of a low cost, passive, and wireless temperature sensor that can withstand high temperature and harsh environment. The temperature sensor was designed following the principle of metamaterials …

Method Development For A Chemical And Biological Analysis Of Glucocorticoids In Wastewater, Maria Carmen Lozano

Open Access Theses & Dissertations

Glucocorticoids are a class of steroid hormones that can either be produced synthetically or naturally by the adrenal glands. The synthetic glucocorticoids are highly prescribed in the United States for their anti-inflammatory and immunosuppressive properties to treat a variety of ailments and diseases; however, these have been implicated in a number of adverse human conditions such as obesity, metabolic syndrome, immune-suppression, delayed puberty, adrenal insufficiency and Cushing Syndrome, among others. Ongoing research has shown that synthetic and natural hormones are transported to aquatic environments via mammalian excretion or wastewater effluent, and as a result, the release of glucocorticoids into the …

Attitude Towards Green Warehousing In El Paso, Texas: An Exploratory Analysis, Lynda Jeanette Macias

Open Access Theses & Dissertations

The increasing reliance on fossil fuels by today's emerging economies has a profound implication on the sustainability of many warehousing and distribution logistical systems worldwide. This research attempts to fill the gap in current green warehousing literature by investigating how warehousing and distribution facilities view greener strategies as a way to increase operation efficiency through a stated preference approach. A survey instrument was developed, and the survey was conducted to identify warehousing characteristics, green practices, and current green views of warehouse managers in El Paso, Texas. The survey results found a balanced outlook within the environment and business needs. Companies …

Nanocomposite And Mechanically Alloyed Reactive Materials As Energetic Additives In Chemical Oxygen Generators, Marco Antonio Machado

Open Access Theses & Dissertations

Chemical oxygen generators are widely used for aircraft, spacecraft, submarines, and mine rescue. Oxygen-generating compositions typically include alkali metal chlorate or perchlorate that decomposes at increased temperatures, a transition-metal oxide as a decomposition catalyst, and a metal fuel that reacts with part of the produced oxygen to provide heat for a self-sustained propagation of the decomposition/combustion wave. To increase the oxygen yield per unit mass, it is of interest to minimize the amount of metal fuel, but decreasing its content leads to pulsating combustion and undesired fluctuations of the oxygen flow rate. This work explores the feasibility of replacing iron …

Process Study And Control Of Electron Beam Melting Technology Using Infrared Thermography, Jorge Mireles

Open Access Theses & Dissertations

An IR camera was installed in an Arcam A2 system (Arcam AB, Mölndal, Sweeden) and layer-by-layer image acquisition was achieved. The camera's capability to detect manufacturing defects was evaluated by implementing computer vision techniques using LabVIEW measurement and programming software (National Instruments, Austin, TX). Thermal maps acquired by the IR camera allowed layer-by-layer part temperature to be recorded. A core objective of this research was to study the impact of processing temperature on EBM-fabricated Ti-6Al-4V parts and achieve controlled mechanical properties. In this research, build variations were achieved by modifying parameters that change processing temperature from the standard processing temperature. …

Experimental Study On The Fabrication Of Advanced Materials For Energy Applications Using High Energy Mechanical Milling, Ashvin Kumar Narayana Swamy

Open Access Theses & Dissertations

The reaction of aluminum (Al) powder with water has the potential for on demand hydrogen generation. Conventional Al powders, however, react with water slowly due to a highly protective oxide layer on the particle surface. Current methods for Al activation involve harmful and expensive materials. The nano-scale Al powders also remain very expensive and have problems such as a large amount of oxide on the surface. The use of aluminum in an energy generation cycle is also hindered by the fact that, although Al is the most abundant metal in the Earth's crust, its recovery from ore consumes a lot …

Manufacturing Nerve Guidance Conduits By Stereolithography For Use In Peripheral Nerve Regeneration, Mireya Aidee Perez

Open Access Theses & Dissertations

Nerve regeneration techniques have been studied in great depth in recent years. Peripheral nerve injuries, in particular, can be caused by accidents, falls, athletic injuries, etc. Current methods of repair include direct suturing of the 2 injured nerve ends or the use of autografts, when a nerve section is taken from another area of the body. Both methods have a series of limitations which have led researchers to study alternative methods of repair. Nerve guidance conduits may provide a viable solution because they can be modified and adapted to the patient's needs. Some conduits already exist on the market and …

Surface Plasmon Polaritons And Waveguide Modes At Structured And Inhomogeneous Surfaces, Javier Polanco

Open Access Theses & Dissertations

In chapter 1, properties of a p-polarized surface plasmon polariton are studied, propagating circumferentially around a portion of a cylindrical interface between vacuum and a metal, a situation investigated earlier by M. V. Berry (J. Phys. A: Math. Gen. 8, (1975) 1952). When the metal is convex toward the vacuum this mode is radiative and consequently is attenuated as it propagates on the cylindrical surface. An approximate analytic solution of the dispersion relation for this wave is obtained by an approach different from the one used by Berry, and plots of the real and imaginary parts of its wave number …