Engineering Commons^™

Mixed-Signal Distributed Feature Extraction For Classification Of Wide-Band Acoustic Signals On Sensor Networks, Humberto Santacruz

Open Access Theses & Dissertations

This thesis proposes a distributed/collaborative scheme for the classification of wide-band acoustic events within the context wireless sensor networks (WSNs). The proposed method is characterized by a mixed-signal processing scheme for the extraction of feature vectors which reduces the processing, memory allocation, and power requirements of the sensor nodes. The mixed-signal scheme assumes that nodes have an analog frontend consisting of a microphone, a bandpass filter, a squaring element and an integrator. This chain of components produces an estimate of the energy over the frequency subband extracted by the filter. The WSN has the ability to form a distributed filter …

Microstructural Architecture Developed In The Fabrication Of Solid And Open-Cellular Copper Components By Additive Manufacturing Using Electron Beam Melting, Diana Alejandra Ramirez

Open Access Theses & Dissertations

The fabrication of Cu components were first built by additive manufacturing using electron beam melting (EBM) from low-purity, atomized Cu powder containing a high density of Cu2O precipitates leading to a novel example of precipitate-dislocation architecture. These microstructures exhibit cell-like arrays (1-3µm) in the horizontal reference plane perpendicular to the build direction with columnar-like arrays extending from ~12 to >60 µm in length and corresponding spatial dimensions of 1-3 µm. These observations were observed by the use of optical metallography, and scanning and transmission electron microscopy. The hardness measurements were taken both on the atomized powder and the Cu components. …

Pressure-Dependent Nanoheteroepitaxy Of Cdte On Si(100) And Soi(100) Substrates Using The Close-Spaced Sublimation Technique, Hoong Yan See Tao

Open Access Theses & Dissertations

CdTe is an ideal II-VI semiconductor compound with a direct bandgap energy of 1.53 eV used in solar cells and infrared detector applications [8]. The National Renewable Energy Laboratory (NREL) reported that cadmium telluride (CdTe) thin films solar cells have achieved efficiency of 16.5% and with potential for improvement up to the theoretical value of 29% [14]. The close-spaced sublimation (CSS) method used for solar cell CdTe growth is being tested for selective CdTe nanoheteroepitaxial growth because the CSS method is cost efficient compared to the molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE) methods. High quality films …

Synthesis, Microstructure And Thermal Analysis Of Gd2o3 - Hfo2 Coatings, Chandan Kumar Roy

Open Access Theses & Dissertations

Thermal barrier coatings (TBCs) are critical for future gas turbines of advanced coal based power generation systems. The TBCs are protective layers of low thermal conductivity ceramic materials, which prevent the damage of components that are exposed to very high temperature of the hot gases. Due to increasing demand to improve the efficiency, it is necessary to find alternate TBC materials which can withstand higher temperature for longer period than state-of-art TBCs. The present study focuses on the Gd2O3 stabilized HfO2 (GSH) as a potential candidate for TBC. GSH materials were synthesized in bulk and coatings form. The Gd2O3 content …

An Evolutionary Approach Based On Viral Replication For Solving Combinatorial Optimization Problems, Claudia Evangelina Valles Sosa

Open Access Theses & Dissertations

A new multi-objective evolutionary algorithm that mimics the way viruses replicate is presented. The purpose of viral replication is to allow the reproduction and survival of its kind. The algorithm is able to produce a large number of solutions to be evaluated by imitating the way viral replication and the infection process work. The well-known multi-objective redundancy allocation problem is used to show the performance of this new viral-based evolutionary approach. The algorithm considers the maximization of system reliability, the minimization of system cost, and the minimization of system weight to be optimized simultaneously. The solution to the multi-objective optimization …

Effect Of Process Parameter On Temperature Distribution, Microstructure, And Mechanical Properties Of Self-Reacting Friction Stir Welded Aluminum Alloy 6061-T651, Monica Adriana Torres

Open Access Theses & Dissertations

Self-reacting friction stir welding is the latest FSW tool configuration developed, it employs two shoulders--one on top and one on the bottom of the workpiece-- this tool configuration offers many advantages over conventional welding techniques. However, the current lack of information and specifications limits its understanding and application. This investigation analyzed the effect of process parameters on temperature distribution, microstructure evolution, and final mechanical properties of 6061-T651 SR-FS welds. A factorial experiment was carried out, in which three-process parameters were analyzed--rotational speed, travel speed, and tool plunge force-- three levels were analyzed for each parameter, except for a tool plunge …

Fabrication And Characterization Of Nanocrystalline Yttrium Oxide Thin Films For Electronic Device Applications, Mudavakkat Vikas Haridas

Open Access Theses & Dissertations

This thesis presents the optimization of growth conditions for fabricating nanocrystalline Yttrium Oxide (Y2O3) thin films on silicon and optical grade, high quality quartz substrates in order to study its structural, optical and electrical properties for electronic device applications.

Commercially Y2O3 has proven to be difficult to fabricate at high quality due to its high temperature growth requirements and the need to alter established fabrication methods for electronic devices. A high temperature requirement for high quality poses a problem for research and analysis. This calls upon for an optimization of the growth conditions to facilitate fabrication of thin films for …

Methodology To Convert A Transportation Planning Origin-Destination Matrix Into A Microscopic Traffic Simulation Origin-Destination Matrix, Jose Osiris Vidana-Bencomo

Open Access Theses & Dissertations

Microscopic traffic simulation (MTS) is a cost-effective approach for the evaluation of traffic conditions in urban highways networks. In MTS models, traffic demand that is entered into the network is specified by one or several Origin-Destination (O-D) matrices. A major challenge in the application of MTS for large urban networks is the specification of the O-D matrices. This dissertation proposes a methodology that may be used to transform a O-D matrix from a transportation planning model (which is based on Traffic Analysis Zone, or TAZ, and is readily available) into a O-D matrix for a MTS model (which is traffic …

A Framework For Strategic Sustainable Supply Chain Design, Abril Paola Vazquez

Open Access Theses & Dissertations

Sustainable supply chain management has raised interest considerably in recent years; due to environmental concerns from society as well industries. There is a high interest in the industries to solve this problem but many of the frameworks are directed to specific situation or structure. A strategic sustainable supply chain design framework is presented with the purpose of providing many companies, including small and big industries, the means to maintain an eco-friendly operation. These include; industry plants, distribution centers, and retailers.

Indentifying And Understanding User Preferences In Generic Planning Tools, Grisel Ventura

Open Access Theses & Dissertations

Planning is an important cognitive work activity. To support this complex task, the development of planning tools is important to support people during decision-making and problem-solving tasks. Nowadays, a large number of manual and electronic tools support this complex activity; manual and electronic planning tools aid people in creating strategies for effective work performance. However, there is limited information on the design of generic planning tools people use for their activities, and why people choose to use the planning tool they do. Some examples of generic tools for planning are calendars, checklists, agendas, etc.

To answer this question, this research …

Analysis Of Indoor And Outdoor Particulate Matter At Various Residences In The El Paso Region, Joseph Christopher Pinon

Open Access Theses & Dissertations

This thesis is a presentation of particulate matter data collected from February 2007 to June 2008. Personal environment monitors (PEM), which measured 7-day PM2.5 concentrations, had been deployed at 14 homes during the 2007 year and deployed in 16 different homes during the 2008 sampling year. Within each sampling year, sampling occurred for two one-week (7-day) periods during each season. In addition to PEM sampling, a tapered element oscillating microbalance (TEOM) continuous sampler had been deployed in both indoors and outdoors at one pre-selected household per week. Gravimetric, chemical, and black carbon analysis had been performed on the PEM PM2.5 …

Experimental Investigation Of Magnesium/Regolith Combustion For In-Situ Production Of Materials On The Moon, Christopher White

Open Access Theses & Dissertations

Future settlements on the Moon will require that strong, cost-effective structural materials be developed in whole or in part from locally available resources. Such materials can be created in-situ from the lunar regolith using self-propagating high-temperature synthesis (SHS). By mixing the lunar regolith with metal additives, such as aluminum or magnesium, a combustible mixture is formed which, when ignited, can reach temperatures high enough to allow combustion to be self-sustaining, sintering the lunar regolith without further energy input and without the need for atmospheric oxygen. The resulting products may be strong enough for some structural applications, such as radiation shielding, …

The Effect Of Cr, Si And B On The Oxidation Behavior On Three Nb-Based Alloys, David Alvarez

Open Access Theses & Dissertations

Nb-based alloys are of particular interest to replace the current Ni-based superalloys for high-temperature structural applications. One important limitation to improve the efficiency of gas-turbine engines is the temperature limit of current materials being used. By allowing the temperature to increase, the efficiency will increase. Nb-based alloys have high melting points and adequate mechanical properties but the oxidation resistance is still inadequate.

This research focuses on the oxidation behavior of three Nb-based alloys to study the effect of Cr and Si variation and look at the effect of Boron. Boron can form a glassy borosilicate which is viscous at high …

Novel Photovoltaic Device For Targeted Drug Delivery, Sunny S. Ambure

Open Access Theses & Dissertations

Despite decades of research, progress in targeted drug delivery is relatively slow, hampered, in part, by the lack of appropriate mechanisms to deliver anticancer drugs selectively to tumor tissues. Systemic or oral administration can cause severe toxicity, which limits the therapeutic potential of anticancer drugs [1]. Therefore, the most important goal of drug delivery is to minimize the exposure of normal tissues to these drugs while maintaining their therapeutic concentration in tumors.

A photovoltaic cell (PV) is a system that converts lights into electricity as well as induces charge transfer by photovoltaic effect. Motivated by such unique property, we have …

Collaborative And Distributed Algorithms For Localization In Wireless Sensor Networks Based On The Solution Of Spatially Constrained Local And Sub-Local Problems, Juan De Dios Cota

Open Access Theses & Dissertations

In this research we present algorithms for the distributed and collaborative localization of nodes for applications in wireless sensor networks. The algorithms are distributed in the sense that each node can estimate its own position using only range information and position estimates from neighboring nodes. The algorithms aim at achieving good accuracy with low computational complexity and low energy consumption. We consider the full localization process consisting of an initialization stage followed by a refinement stage.

For initialization, we propose a \emph{bilateration} algorithm where each node uses a set of anchors and their respective ranges to solve a set of …

Residential Recycling Study, Richard Adams

Open Access Theses & Dissertations

The purpose of this study is to gain baseline performance figures and statistics for El Paso's curbside recycling program. With these baseline statistics the effectiveness of changes for promotion and outreach can be evaluated once implemented. In addition, operational changes such as to every other week recycling collection rather then every week or a "pay as you throw" system could be evaluated.

Evaluation Of Nondestructive Technologies To Assess Presence And Extent Of Delamination Of Hot Mix Asphalt Airfield Pavements, Manuel Celaya

Open Access Theses & Dissertations

Sufficient bonding between the hot mix asphalt layers is essential to ensure the desired structural capacity of a pavement. Delamination or debonding problems are particularly more severe on airfield pavements, due to higher traffic loads applied by aircrafts. Further progression of delamination may result in stripping of the lower layers due to the intrusion of moisture or may develop other dangerous distresses such as foreign object debris. The existing nondestructive testing procedures and equipment that have the potential to address the problem were identified and their effectiveness and potential for success were evaluated. The Ground Penetrating Radar, Falling Weight Deflectometer, …

Impact Of Truck Suspension And Road Roughness On Loads Exerted To Pavements, Shahram Misaghi Bonabi

Open Access Theses & Dissertations

A software package, called IntPave, an Integrated Pavement Damage Analyzer, was developed at the Center of Transportation Infrastructure Systems at The University of Texas at El Paso with the capacity to calculate the pavement distress for flexible pavements under any type of traffic load, and to make a comparison of the level of distress caused by a standard and a non-standard, assuming statically exerted loading. However, what has been lacking is a tool to measure the dynamic impact on the pavement due to vehicle-road interaction. In this report, the interaction of truck suspension systems with the roughness of the road …

Size Dependent Melting And Diffusion Of Silicon For Microsystem Applications, Noel Felipe Marquez

Open Access Theses & Dissertations

The size dependent reduced melting point and hydrogen enhanced surface diffusion effect on silicon nanostructures was explored experimentally. SOI and silicon wafers were patterned using nanimprint lithography and dry etching to explore the reduced melting point effect; and patterned with photolithography and dry etching to explore the hydrogen enhanced surface diffusion. The nanotextured samples were annealed in a wide variety of furnaces with nitrogen, forming gas, and argon atmospheres. Nitrogen was found to block the reshaping effect while argon was found to cause extensive pitting damage in the setup used. Micropatterned samples were annealed in a low pressure hydrogen enabled …

Oxidation Of Zrb2-Tic-Y2o3 At 1700c, Brenda Mota

Open Access Theses & Dissertations

The oxidation of plasma-sintered ZrB2-TiC-Y2O3 samples in air and a CO/N2 atmosphere has been investigated at 1973 K. The TiC was added to develop a TiO2 similar to a SiO2 layer, which has been an effective diffusional layer for the ZrB2-SiO2 system. Yttria was added to determine whether sufficient stabilization of the tetragonal-ZrO2 (t-ZrO2) could occur to minimize the monoclinic-ZrO2 transformation, which causes susceptibility to thermal shock of any ZrO2 containing composite.

The oxidized samples developed an outer layer of TiO2-B2O3 liquid acting as a sealant but with significant voidage as a result of B2O3 vaporization. Cracking initiated on the …

Conformal Electronics Packaging Through Additive Manufacturing And Micro-Dispensing, Richard I. Olivas

Open Access Theses & Dissertations

Realizing electronic systems that are conformal with curved or complex surfaces is difficult if not impossible with conventional fabrication techniques, which require rigid, two dimensional, printed circuit boards (PCB). Flexible copper based fabrication is widely available commercially providing conformance, but not simultaneously stiffness. As a result, these systems are susceptible to reliability problems if repeatedly bent or stretched. The integration of Additive Manufacturing (AM) combined with Direct Print (DP) micro-dispensing can produce shapes of arbitrary and complex form that also allows for 1) miniature cavities for insetting electronic components and 2) conductive traces for electrical interconnect between components. The fabrication …

Bioprinting Oxygen Releasing Microparticles For Improved Cell Tissue Viability, Daniel Reyna

Open Access Theses & Dissertations

A major challenge in regenerative medicine/tissue engineering is the difficulty of providing adequate oxygen to all cells within implanted engineered tissues before full vascularization is achieved. To overcome this limitation, a variety of oxygen-releasing particles have been developed to improve cell and tissue survival. However, most of these particles are used in random mixtures within scaffolding materials, which usually leads to an uneven distribution of oxygen in bioengineered tissues. An ideal oxygen supply requires a precise depositing control of oxygen-releasing particles in scaffolds. Cell bioprinting is a novel tissue fabrication approach, in which the bio-printer can be programmed to deposit …

Assessment Of Intra-Urban Traffic-Related Air Pollution On Asthmatic Children's Exposure At Schools In The Paso Del Norte Region, Amit Ugamraj Raysoni

Open Access Theses & Dissertations

Traffic-related air pollution can be a major public health concern in any urban area. This problem is compounded in the Paso del Norte region that has experienced rapid economic growth, and a substantial number of people living in close vicinity of major roadways. The desert surroundings, arid weather, frequent temperature inversions, heavy border traffic at the international ports of entry between El Paso and Ciudad Juárez, and poorly maintained vehicle fleet further exacerbates this problem. A growing body of air quality and epidemiologic research has discerned the linkage between traffic emissions and respiratory disorders.

Initial health investigations in the Paso …

Algorithms For Training Large-Scale Linear Programming Support Vector Regression And Classification, Pablo Rivas Perea

Open Access Theses & Dissertations

The main contribution of this dissertation is the development of a method to train a Support Vector Regression (SVR) model for the large-scale case where the number of training samples supersedes the computational resources. The proposed scheme consists of posing the SVR problem entirely as a Linear Programming (LP) problem and on the development of a sequential optimization method based on variables decomposition, constraints decomposition, and the use of primal-dual interior point methods. Experimental results demonstrate that the proposed approach has comparable performance with other SV-based classifiers. Particularly, experiments demonstrate that as the problem size increases, the sparser the solution …

High Temperature Oxidation Behavior Of Nb-20si-20cr Alloys With Hafnium Additions, Alma Rosa Vazquez

Open Access Theses & Dissertations

Advances in aircraft and gas turbine engine technology have steadily increased the operating temperatures, and even the state of the art materials can not meet the requirements for the new challenges. Efforts are under way to study the possibility of substituting nickel-based alloys with niobium-based alloys that offer higher melting points and excellent mechanical properties. Notwithstanding these good properties, the utilization of Nb-based alloys is limited since oxidation resistant is still a serious problem. Therefore understanding the corrosion behavior of Nb-based alloys is a crucial step to enhancing oxidation resistance.

The oxidation behavior of two alloys from the Nb-Si-Cr system …

Asphaltene As Light Harvesting Material In Dye Sensitized Solar Cell, Rajab Emhemed Abujnah

Open Access Theses & Dissertations

This Dissertation characterizes the first asphaltene DSSC (dye-sensitized solar cell), in which light to electricity conversion efficiency has improved from 0 % to 1.8 %. Four natural organic asphaltene factions, namely, un-fractionated asphaltene, Fr. 1 Asphaltene, Fr.2 asphaltene, Fr.3 and Fr.4 were extracted and tested for various solar cell parameters of TiO2 based dye-sensitized solar cell DSSC. DSSCs were fabricated using the four individual asphaltene dyes. The photovoltaic performance of the cells was examined by determining the various parameters such as open-circuit voltage, short-circuit current, fill factor, and series resistance. The overall energy conversion efficiency was also measured to correlate …

Adaptation Of Low Impact Design To The Desert Southwest, Abubaker Ali Alamailes

Open Access Theses & Dissertations

A low Impact Development (LID) practices were used to design an Integrated Management Practices (IMP) system for a residential lot .The design was adapted to the Desert Southwest region based on twenty years of climate data including precipitation and temperature for three representative cities: El Paso, TX, Albuquerque, NM, and Phoenix, AZ. In order to capture stormwater runoff close to its source and to provide as much stored water as possible for plants, LID practices including bioretention cells and vegetated swales were applied throughout the lawn. The purpose of the design is to maintain the pre-development hydrologic characteristics of the …

Software And Hardware Techniques To Aid In Automating And Troubleshooting Hybrid Systems That Fabricate Three-Dimensional Electronics, Mohammed Alawneh

Open Access Theses & Dissertations

Various issues in automating the fabrication of three dimensional electronics were addressed in this thesis. The three dimensional electronics were fabricated by a stereolithoraphy and direct print hybrid system. Hardware and software limitations were discussed and possible solutions were implemented. Various automation software tools were developed, specifically a computer aided design to printed electronics conversion software compatible with various stages.

Automated Detection Of Dust Clouds, Sources, And Direction From Noaa-Avhrr Satellite Imagery, Mohammed Qassim Alkhatib

Open Access Theses & Dissertations

This research is mainly focused on automatically locating dust sources and estimating their transport direction in NOAA-AVHRR images. Applications of AVHRR images may include agricultural assessment, producing maps of large area, and to retrieve various geophysical parameters. The AVHRR simultaneously records five bands of data, in our research, we focused on bands four and five since these wavelengths highlight the absorption and subsequent emission of thermal radiation by the silicate particles in the dust storms.

In this research, we propose a new method to detect dust clouds on satellite images. The approach we propose involves the use of an image …

Combustion Of Lunar Regolith Mixed With Energetic Additives: Thermodynamic Calculations And Experimental Studies, Francisco Alvarez

Open Access Theses & Dissertations

The future of space exploration will require longer missions in order to better understand the conditions of near-Earth celestial objects, like the Moon or Mars. Future space missions will require the development of goods, such as propulsion fuel and structural materials, produced using the extraterrestrial resources available. The area that develops these technologies is called In-Situ Resource Utilization (ISRU). ISRU allows reducing the payload, and as a consequence reduces the energy consumption and cost of space travel. The production of structural materials on the Moon can be accomplished using Self-Propagating High-Temperature Synthesis (SHS). This work describes the combination of ISRU …