Physical Sciences and Mathematics Commons^™

Use Of Cognitive Constructs In Linear Algebra, Azucena Zamora

Open Access Theses & Dissertations

Thesis analyzed the presence of two cognitive entities-- modes of thinking and metonymies and metaphors- in the reasoning of three students enrolled in a first year matrix algebra course at a southwest university via the responses given to a set of eight questions asked during one-on-one interviews. The findings of our analysis shed light on the cognitive constructs that students employ to form their understanding of linear algebra concepts. Furthermore, our findings provide clues about the ways in which students move from one mode of thinking to another in the context of varying levels of exposure to graphical, algebraic, and …

Tectonic Geomorphology Of The Puna Tsang Chhu, Western Bhutan, Abby May Woody

Open Access Theses & Dissertations

There are two boundaries, or physiographic transitions, between three distinct topographic regions in Bhutan. The southern and northern regions have relatively steep hillslopes and high relief, while the central region has gentle hillslopes and low relief. The geomorphology of a 70-km stretch along the Puna Tsang Chhu valley between the towns of Uma and Amrimo was studied in March and April of 2009 to provide constraints on the active tectonics of western Bhutan and the nature of these physiographic transitions.

The Puna Tsang Chhu valley contains a set of alluvial cut-and-fill and bedrock (strath) river terraces with associated sediments - …

Titanium Niobium Nano Porous Materials: New Photocatalysts For Water Decontamination, Maryam Zarei Chaleshtori

Open Access Theses & Dissertations

Water pollution is major environmental problem worldwide. Many common industrial organic compounds that make their way into water systems can be carcinogenic at trace levels and are difficult and costly to remove completely with conventional technologies. Because of this, authorities and researchers are trying to improve current water cleanup techniques.

Heterogeneous photocatalysts that accelerate the photocatalytic destruction of organic contaminants in water are a potentially inexpensive and highly effective way to remove both trace-level and saturated harmful compounds from industrial waste streams and drinking water. Titanium dioxide has the potential to completely mineralize organic compounds in water under ultraviolet light. …

Urban Development Under Extreme Hydrologic And Weather Conditions For El Paso-Juárez: Recommendations Resulting From Hydrologic Modeling, Gis, And Remote Sensing Analyses, Alberto Barud-Zubillaga

Open Access Theses & Dissertations

During the 2006 El Paso-Juárez flood there were many concerns regarding the capability of the existing stormwater system to handle 50- and 100-year flood events in El Paso, Texas and Juárez, Mexico area. Moreover in 2008, a considerable wet year from the normal 223 mm of annual precipitation for El Paso demonstrated that the area could very well received large amounts of precipitation at localized areas in short periods of time, representing a great flood threat to residents living in areas prone to flood. Some climate change projections for the area are exactly what had occurred over the last two …

Application Of Copper And Zinc Isotopes To Fingerprint Metal Sources And Identify Attenuation Mechanisms In The Abandoned Waldorf Mine Area, Clear Creek County, Colorado, Suzan Aranda Luna

Open Access Theses & Dissertations

Acid rock drainage (ARD) is caused by the oxidative weathering of sulfide minerals. Sulfur is oxidized by dissolved oxygen or Fe(III) and sulfate ions, metals, and protons are released into the environment. Hence, the pH of nearby water and soils often decreases in response to ARD while metal concentrations increase. Because a large part of the Rocky Mountains of Colorado are highly mineralized (i.e., the Colorado Mineral Belt), ARD is a serious problem in this region. Moreover, the many abandoned mining areas in the Rocky Mountains that include waste rock piles, tailings impoundments, and surface disturbances add to the problem …

Use Of The Cmaq And Wrf-Chem Models To Investigate Tropospheric Ozone And Particulate Matter In The El Paso-Juarez Airshed, Juan Gustavo Arias Ugarte

Open Access Theses & Dissertations

Ground level ozone pollution is a continuing environmental concern in several U.S cities. A necessary step towards understanding and quantifying the problem is the implementation of numerical models that can predict pollutant concentrations. Simulations were performed using the Community Multiscale Air Quality (CMAQ) and the (Weather Research Forecast/Chemical (WRF-Chem) models to study the tropospheric ozone and particulate matter concentrations in the El Paso-Juarez Airshed and to analyze the influence of U.S and Mexican cities as possible contributors to ground level ozone pollution in this region. This study involves the implementation and validation of both the CMAQ and WRF-Chem models for …

Simulation And Optimization Of Ultra Thin Photovoltaics, Jose Luis Cruz-Campa

Open Access Theses & Dissertations

Sandia National Laboratories (SNL) conducts pioneering research and development in Micro-Electro-Mechanical Systems (MEMS) and solar cell research. This dissertation project combines these two areas to create ultra-thin small-form-factor crystalline silicon (c-Si) solar cells. These miniature solar cells create a new class of photovoltaics with potentially novel applications and benefits such as dramatic reductions in cost, weight and material usage.

At the beginning of the project, unusually low efficiencies were obtained in the research group. The intention of this research was thus to investigate the main causes of the low efficiencies through simulation, design, fabrication, and characterization.

Commercial simulation tools were …

The Composition Of Precipitation In El Paso, Texas, Sonny P. Emmert

Open Access Theses & Dissertations

The composition of precipitation reflects the transport of particles from varying air mass source regions as well as input from local environmental and anthropogenic activities. Air research in El Paso, TX, U.S.A/Ciudad Juarez, Chihuahua, Mexico has been traditionally limited to studies of local inputs of air pollution; no transition has been made to studying the scavenging, washout, and transport of pollutants by precipitation. The goal of this research project was to identify transported pollutants in precipitation, and determine if there were any health and ecological implications. The research investigated biological, chemical, and geological constituents in precipitation samples collected between September …

Gaze, Turn-Taking And Proxemics In Multiparty Versus Dyadic Conversation Across Cultures, David Alberto Herrera

Open Access Theses & Dissertations

When people converse with others, they participate in joint interaction behaviors, like proxemics or interpersonal distance, mutual gaze, and turn-taking or pause and overlap, which they may not consciously negotiate. How these behaviors manifest depends on many factors, such as gender, age, personality, culture, and number of participating conversants. Understanding these differences is important for situations where intercultural joint interaction behaviors are necessary for mission success, such as for military personnel in foreign countries. They may also be useful for modeling embodied conversational agents where culture and group vary. Joint interaction behaviors have been extensively studied for American dyads, and …

Hydrological Characteristics Of A Large-Scale Flooding And Draining Experiment, Barrow, Alaska, Edith Jaurrieta De Velasco

Open Access Theses & Dissertations

The Arctic appears to be affected by climate change more so than any other region on Earth. Some of the most significant climate change impacts reported for the Arctic are associated with dramatic shifts in the hydrologic regime of terrestrial ecosystems. Understanding the hydrologic processes that are associated with different components of arctic terrestrial ecosystems is important because water in the form of snow or rain influences a range of properties and processes such as land-atmosphere energy and trace gas fluxes, nutrient cycling, ecosystem dynamics, biodiversity, periglacial processes and surface albedo. Furthermore, plants, animals, and native people of the Arctic …

Scrap Reduction Model: By Combination Of Dmaic And Design Of Experiments, Anoop J. Randive

Open Access Theses & Dissertations

This project deals with the experimentation which took place at a cable manufacturing company. The thesis describes and summarizes the various strategies and techniques that has been applied and practiced for scrap reduction. DMAIC and Six Sigma Technology has been proven very help full in order to reduce scrap to a major extent. DMAIC help to identify areas in process where extra expense exist, identify the biggest impact factor related production expenses, introduce appropriate measurement system, optimize process and reduce production cost and time. Many issues were detected by the production, such as a lack of a unified procedure for …

Development Of Nanotube Hexaniobate For Photocatalytic Production Of Hydrogen From Water, Saroja Pradhan

Open Access Theses & Dissertations

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Granulometry And Geochemistry Of Dust Emission From Owens (Dry) Lake, California, Analila Rojo

Open Access Theses & Dissertations

Owens (dry) Lake, the terminus of Owens River, is located in the Basin and Range physiographic province in east–central California. The transformation of Owens Lake into a desiccated desert playa (approximately 280 km2) via diversion of the river into the Los Angeles Aqueduct (in 1913) led to extensive wind erosion, making the playa one of the most intense sources of airborne dust in the Western Hemisphere. The processes that direct the chemical and mineralogical composition of surface sediments at Owens (dry) Lake and the physical mechanisms of wind erosion, saltation and dust emission at Owens (dry) Lake are well–understood. However, …

Mineralization In The San Juan Mountains, Colorado, William M. Sheriff

Open Access Theses & Dissertations

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Resistivity And Conductivity Studies Of The Rattlesnake Springs, New Mexico Watershed, Claudia Santiago

Open Access Theses & Dissertations

Rattlesnake Springs are a high-discharge artesian springs situated in the upper Black River Valley in southwestern Eddy Country, New Mexico. The aquifer that supplies the Rat- tlesnake Springs has been the main water source for domestic use by visitors of Carlsbad Caverns National Park and residents of neighboring ranches since the 1930s. Several ge- ological studies relying on surface geology and limited water wells had previously been conducted in the area to examine the trend of ground water flow. In this study I used con- ductivity and resistivity geophysical techniques to identify possible locations of fractures in the subsurface of …

Salt Separation Processes In Salt Cedar, Rudy Sookbirsingh

Open Access Theses & Dissertations

Salt cedar (genus Tamarix, Family Tamaricaceae) is an exotic, invasive plant in southwestern North America; it has a poor reputation as a heavy-consumer of water and a threat to the landscape and ecology of the region. This study focuses upon saltseparation mechanisms in the salt cedar species Tamarix ramossissima (Ledeb.) which were investigated with a variety of microscopic techniques. The results indicate that this species can produce different salt crystal aggregates morphologies from its vesiculated trichomes, and may use variable mechanisms for separating anions and cations of various salts. It was additionally found that salt crystals aggregates in this species …

Microwave Assisted Solid-Supported Organic Synthesis: A Novel Methodology To Obtain 2,3-Disubstituted-1,4-Naphthoquinones, Israel Garcia-Martinez

Open Access Theses & Dissertations

This research focuses on the combinatorial solid phase organic synthesis (SPOS) of different bioactive compounds utilizing transition metal mediated reactions via microwave assisted organic synthesis (MAOS).

A microwave-assisted solid-supported Dötz benzannulation of chromium Fischer carbene complexes with various alkynes has been reported. The oxidative cleavage of the resulting resin-bound 1,4-naphthols affords 2,3-disubstituted-1,4-naphthoquinone derivatives in good to moderate yields with high purities. We demonstrated that solid phase organic synthesis of naphthoquinones via conventional heating is limited due to their long reaction times and high temperatures. The products decompose leading to low yields and purities.2 Microwave assisted synthesis of these naphthoquinones will …

Nutrient Dynamics In A Created Desert Wetland: Implications For The Rio Bosque Wetlands Park, Ruth Rodriguez

Open Access Theses & Dissertations

Rio Bosque Wetland Park is an arid wetland currently under restoration, which primarily receives water inputs from the Bustamante Waste Water Treatment Plant (WWTP) during the non-irrigation season. Understanding the ability of a desert wetland to remove nutrients from the water column through uptake by primary producers or sediment transformations is key to justifying the protection and creation of other similar wetland sites. Nitrate concentrations tended to be reduced, relative to the inflow, near the outflow of the wetland.To further understand these trends, sediment nutrient release experiments and algal nutrient limitation experiments were completed. Sediment phosphorus release experiments indicated that …

Analysis Of Shallow Seismicity And Stress Fields In Southeastern Alaska, Hugo Rodriguez

Open Access Theses & Dissertations

Southeastern Alaska is dominated by strike-slip motion along the Queen Charlotte-southern Fairweather fault system (QCFS) in the south and transitions to oblique convergent motion partitioned between strike-slip motion along the Denali and northern Fairweather fault systems and thrusting along faults of the St. Elias region. Geologic complications are further increased by the subduction of the Yakutat microplate beneath North America and glacial processes. By studying regional background seismicity we intend to better determine the current state of stress of southeastern Alaska from the Dixon Entrance to Yakutat Bay. Phase data was gathered for over 4000 earthquakes of depths <20 km and magnitude <5 that occurred from 1973-2005 from Alaskan and Canadian databases. We relocated these earthquakes using the Double-Difference joint hypocenter method. Two areas of interest were identified with high concentrations of seismicity after relocation calculations for the entire southeast Alaska region; Glacier Bay through Yakutat (GBY) and the area surrounding Mt. Ogden (MOG). Earthquake locations in GBY are diffuse with some isolated clusters. The MOG subregion is dominated by a large northeast to southwest trending cluster that trends along the Speel River. We used these relocations and first motion data to estimate the stress fields for earthquake clusters that formed. Only a few of the calculated stress tensors were successful in representing the region's overall tectonic signature. We combined the calculated stress information with GPS, magnetic and gravity data in order determine how plate motion is partitioned in this region and to identify other potentially active faults.

Examples Of Hyperbolic Knots With Distance 3 Toroidal Surgeries In The 3-Sphere, Cesar Garza

Open Access Theses & Dissertations

By the work of Thurston, any surgery on a hyperbolic knot in the 3-sphere produces a hyperbolic 3-manifold except in at most finitely many cases. So far, the figure-8 knot seems to be the best candidate for a hyperbolic knot with the most (8) non-trivial exceptional surgeries. In recent years, much progress has been made in the classification of hyperbolic knots admitting more than one exceptional toroidal surgery. In fact, such classification is known for toroidal surgeries with distance at least 4.

We give a classification of hyperbolic knots in $S^3$ admitting two toroidal surgeries at distance 3, whose slopes …

An Optimization Approach For The Cascade Vulnerability Problem, Christian Servin

Open Access Theses & Dissertations

In inter-connected systems, where several computers share information with each other, problems may arise when inappropriate information starts to flow through. For example, let us consider a simple scenario of a university composed of three departments: payroll, financial aid, and academic services. We know that the payroll department deals with sensitive information, such as social security numbers, dates of birth, amounts of wages, etc. The financial aid department may use information that payroll owns. Similarly, the academic department communicates with the financial aid department. An intruder can take advantage of this network connectivity and create an inappropriate flow of information …

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 …

Exponential Dichotomy Of Ode's, Nada Farid Al-Hanna

Open Access Theses & Dissertations

I present an elementary Functional Analytic proof of the roughness of Exponential Dichotomy of Ordinary Differential Equations (with exponential growth) on an arbitrary Banach Space.

Electroweak Scale Neutrinos, Enrique Diaz-Mendez

Open Access Theses & Dissertations

We study a model of neutrino mass generation at the Electroweak scale (EW), where Lepton number is broken by the vacuum expectation value of a Standard Model singlet complex scalar field. No energy scales higher than the EW scale are introduced in the model and neutrinos can still get their tiny masses through the general seesaw mechanism. The neutrino Yukawa couplings need not be more suppressed than that of the electron. As part of our results we present the branching ratios of the possible Higgs decays, which should be detectable at near future colliders.

The Isotopological Homodesmotic Reaction: A Further Refinement To The Quantification Of Aromaticity, Marco Olguin

Open Access Theses & Dissertations

Aromaticity imparts a significant energetic stabilization to various chemical systems as a result of cyclic pi-electron delocalization. One of the most widely used methods for the quantification of the Aromatic Stabilization Energy (ASE) of a molecule is the formulation of a Homodesmotic reaction. The following research employs a refined Homodesmotic approach based on previous work by Herndon and Mills which utilized Isotopological Homodesmotic Reactions (IHR) to determine the Aromatic Stabilization Energy (ASE) of a flourenyl cation. The advantage of employing an IHR for an ASE calculation is that the strain energy contribution from the sigma framework of reactant and product …

Studies Of Prompt Gamma And Neutron Yield Due To 2.5 Mev Neutrons Using Geant4, Jesus Felipe Tovar

Open Access Theses & Dissertations

In the present work the software GEANT4, a particle transport toolkit based on the Monte Carlo method, developed mostly by CERN, but also by other institutions and universities. GEANT4 is here used to simulate the dispersive effects that 2.5 MeV neutrons undergo after interacting with different elements. This study has the main interest of identifying spectral signatures, that is the type and number of particles yielded after neutron bombardment of special nuclear material under various shielding conditions. Shielding is composed of various attenuating materials with simple geometrical configurations, that can evolve into more intricate geometries through Boolean operations, enclosing a …

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 …

Earth Field Magnetic Resonance Imaging And Paramagnetic Contrast Agents, Saideh Sadat Mortazavi

Open Access Theses & Dissertations

The goal of this research was to visualize the uptake of copper by plants to aid phyto-remediation research. The hypothesis was that regions of the plant with more copper will have an enhanced NMR signal using copper as a paramagnetic contrast agent.

As the name implies, Earth Field Magnetic Resonance Imaging (EFMRI) spectrometry uses a magnetic field 300,000 times weaker than a 600 MHz Nuclear Magnetic Resonance (NMR) spectrometer. Just like in conventional human MRI, this portable instrument is capable of recording one, two and three dimensional images though the sample size is much smaller.

The enhancement of signal was …