Digital Commons Network^™

Environmental Assessment Of Used Motor Oil In The Ciudad Juarez-El Paso Area, Alma Leticia Figueroa

Open Access Theses & Dissertations

As a hazardous waste generated in large amounts worldwide, used motor oil (UMO) is an important issue for environmental science. UMO contains the carcinogenic and mutagenic compounds Polycyclic Aromatic Hydrocarbons (PAHs). Unless properly managed and disposed of PAHs remain in the environment, principally in sediments and soil. From such environmental sinks, PAHs can migrate to watersheds contaminate drinking water, and damage ecosystems and human health.

Generators of used oil include "businesses that handle used oil through commercial or industrial operations or from the maintenance of vehicles and equipment," (United States Environmental Protection Agency (USEPA), 2013). An example of such a …

Gadolinia Doped Hafnia (Gd2o3- Hfo2) Thermal Barrier Coatings For Gas Turbine Applications, Satya Kiran Gullapalli

Open Access Theses & Dissertations

Thermal efficiency of the gas turbines is influenced by the operating temperature of the hot gas path components. The material used for the hot gas path components can only withstand temperature up to a certain limit. Thermal barrier coatings (TBC) provide the additional thermal protection for these components and help the gas turbine achieve higher firing temperatures. Traditionally available yttria stabilized zirconia (YSZ) TBCs have a limitation up to 1200 C due to their phase transformation. The present work focuses on gadolinia based hafnia (GSH) TBCs to study their potential to replace the YSZ coatings. Different compositions of gadolinia doped …

Geophysical Model Of The Cu-Mo Porphyry Ore Deposit At Copper Flat Mine, Hillsboro, Sierra County, New Mexico, Adrian Emmanuel Gutierrez

Open Access Theses & Dissertations

A 3D gravity model of the Copper Flat Mine was performed as part of the exploration of new resources in at the mine. The project is located in the Las Animas Mining District in Sierra County, New Mexico. The mine has been producing ore since 1877 and is currently owned by the New Mexico Copper Corporation, which plans o bringing the closed copper mine back into production with innovation and a sustainable approach to mining development. The Project is located on the Eastern side of the Arizona-Sonora-New Mexico porphyry copper Belt of Cretaceous age. Copper Flat is predominantly a Cretaceous …

Furthering Our Understanding And Assessing The Effectiveness Of Scaling Patterns And Controls Of Land-Atmosphere Carbon Exchange In A Shrubland Of The Chihuahuan Desert With Novel Cyberinfrastructure, Aline Jaimes

Open Access Theses & Dissertations

Over the last century, arid and semiarid regions have undergone intense desertification and in many regions, vegetation has shifted from grassland to shrubland dominated ecosystems. This land cover change has important implications for how desert ecosystems function - especially with regards to land-atmosphere exchange of carbon, water, and energy. Although the extent of desertified landscapes is expected to expand over the next 30 to 40 years, there is a relatively poor understanding of how this state transition will impact ecosystem function and feedbacks to other components of the earth system. Key to addressing this challenge is an improved understanding of …

3d Printing Technology Using High Viscous Materials-Synthesis Of Functional Materials And Fabrication Of 3d Metal Structure, Seongik Hong

Open Access Theses & Dissertations

In the 3D printing technology, the research for using various materials has been performing. In this research work, 3D printable high viscous materials are suggested as one of the solutions for problems in the traditional 3D printing technology.

First, Cu-Ag coreshell was synthesized as a functional material. In terms of the reaction rate, reaction rate limiting step was defined as a fundamental research, and then prepared Cu-Ag coreshell was printed and analyzed. Second, the high viscous Cu paste was prepared and then metal 3D printed structure was fabricated by using new printing method.

In the synThesis of Cu-Ag coreshell, different …

An Optimization Of Neighbor Discovery In Mobile Ad Hoc Networks, Felipe Jovel

Open Access Theses & Dissertations

This Thesis aims to improve the performance of Mobile Ad Hoc Networks (MANETs) that use soft-state signaling for neighbor discovery, specifically OLSR. In particular, it uses simulations and previous work based on experiments conducted on a physical test bed to study the behavior of the neighbor-discovery algorithm used by OLSR to identify and explore ways to optimize the neighbor-discovery process. Candidate optimizations include the actual and relative settings of the refresh and expiry timers used by the algorithm.

Previous studies focused on understanding how the settings of the algorithms Hello Interval (δ) and TC Interval refresh timers affect network performance …

Decision Making Model For Foreign Object Debris/Damage (Fod) Elimination In Aeronautics Using Quantitative Modeling Approach, Jose Jaime Lafon

Open Access Theses & Dissertations

(FOD) Foreign Object Debris/Damage has been a costly issue for the commercial and military aircraft manufacturers at their production lines every day. 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 standards. Nowadays, FOD is currently addressed with prevention programs, elimination techniques, and designation of FOD areas, controlled access to FOD areas, restrictions of personal items entering designated areas, tool accountability, etc. All of the efforts mentioned before, have not shown a significant …

2tl: A Raid I/O Scheduling Algorithm For Simultaneously Providing Latency And Throughput Guarantees, Yipkei Kwok

Open Access Theses & Dissertations

It is increasingly common for applications to require that data read from and written to a shared storage system be delivered within a specified amount of time (usually milliseconds), called a latency requirement, or be delivered at a specified rate (measured in megabytes per second), called a throughput requirement. Given an input/output (I/O) workload, which consists of the streams of I/O requests of a set of applications, the storage system, via its I/O scheduler, is expected to simultaneously meet the workload's latency and throughput requirements. In addition, it is expected to provide performance guarantees, i.e., guarantees that it will meet …

Towards Analytical Techniques For Optimizing Knowledge Acquisition, Processing, Propagation, And Use In Cyberinfrastructure, Leonardo Octavio Lerma

Open Access Theses & Dissertations

For many decades, there has been a continuous progress in science and engineering applications. A large part of this progress comes from the new knowledge that researchers acquire, propagate, and use. This new knowledge has revolutionized many aspects of our life, from driving to communications to shopping. Somewhat surprisingly, there is one area of human activity which is the least impacted by the modern technological progress: the very processes of acquiring, processing, and propagating information. When we decide where to place sensors, which algorithm to use for processing the data - we rely mostly on our own intuition and on …

Experimental Investigation Of Syngas Flame Stability Using A Multi-Tube Fuel Injector In A High Pressure Combustor, Sergio Elzar Maldonado

Open Access Theses & Dissertations

Over 92% of the coal consumed by power plants is used to generate electricity in the United States (U.S.). The U.S. has the world's largest recoverable reserves of coal, it is estimated that reserves of coal will last more than 200 years based in current production and demand levels. Integrated Gasification Combined Cycle (IGCC) power plants aim to reduce the amount of pollutants by gasifying coal and producing synThesis gas. SynThesis gas, also known as syngas, is a product of coal gasification and can be used in gas turbines for energy production. Syngas is primarily a mixture of hydrogen and …

A Long- And Short-Run Analysis Of Electricity Demand In Ciudad Juarez, Ericka Cecilia Mendez

Open Access Theses & Dissertations

Economic growth and appliance saturation are increasing electricity consumption in Mexico. Annual frequency data from 1990 to 2012 are utilized to develop an error correction framework that sheds light on short- and long-run electricity consumption behavior in Ciudad Juarez, a large Mexican metropolitan economy at the border with the United States. The results for this study reveal that electricity is an inelastic normal good in this market. Moreover, natural gas is found to be a weak complement to electricity. With regards to the customer base in this urban economy, population, employment, and income exercise positive and statistically significant impacts on …

Using Fair Division Methods For Allocating Transportation Funds, Edith Montes

Open Access Theses & Dissertations

Current transportation funding allocation methods are very complex due to limited budgets and conflicting interests. In order to maintain an efficient infrastructure transportation system, agencies must balance the allocation of funds required either to increase the roadway capacity or to preserve the existing roads in service. Depending on the target objectives and specific constraints, the funding allocation process is approached using different methods. The funding allocation process is usually addressed using expert judgment which involves subjective criteria, weighted formulas with pre-established priorities, or a combination of both. However, formula-based funding allocation methods may lead to the public's disagreement if final …

Impact Of Zinc Oxide Nanoparticles On Green Pea Plant & Seed Quality And Effects On Physiological Traits Of Green Peas, Corn, And Zucchini By Silver Nanoparticles, Arnab Mukherjee

Open Access Theses & Dissertations

The production and use of numerous engineered nanomaterials (ENMs) have increased exponentially over the past decade. Nanoparticles (NPs), ENMs possessing diameter between 1-100 nm, (NPs), are widely used in many applications. Worldwide consumption of NPs has increased their possible release into the environment. This, in turn, has elevated the extent of the potential impacts of NP exposure to living and non-living organisms. This is why the assessment of the impact of NPs on different environmental components, especially on plants, the producer in the food web, has become a very important aspect of nano-ecotoxicology. However, studies focusing on phytotoxicity and effects …

Runtime Pipeline I/O Scheduling System For Gpu-Based Heterogeneous Architectures, Julio Cesar Olaya

Open Access Theses & Dissertations

Heterogeneous architectures can improve the performance of applications with computationally intensive operations. Even when these architectures may reduce the execution time of applications, there are opportunities for additional performance improvement as the memory hierarchies of the central processor cores and the coprocessor cores are separate. Applications running on heterogeneous architectures where graphics processing units (GPUs) execute throughput-intense, data-parallel operations may run in a single address space provided by unified virtual addressing or expand the upper bounds of scalability and high performance computing by explicitly partitioning and transferring data across orthogonal host and device address spaces. For explicit handling, applications must …

High-Recovery Inland Desalination: Concentrate Treatment By Electrodialysis And Batch Reverse Osmosis, Noe Ortega-Corral

Open Access Theses & Dissertations

Since fresh water resources are finite and stressed, it is of the utmost importance to develop alternative water resources. Efforts to recover and treat impaired water are happening in arid areas around the world, where water resources are already scarce. Such efforts are particularly focused on high-recovery treatment systems, accomplished by reducing the amount of liquid discharge with the intent to eventually reach zero liquid discharge. The goal of this research is to improve the feasibility of highrecovery inland desalination systems. Two types of high-recovery treatment systems were selected for study: (1) combined reverse osmosis (RO) and electrodialysis (ED) systems, …

Development Of A Transferable Student Engagement And Knowledge Retention Framework For The Earth Sciences, Sunay Palsole

Open Access Theses & Dissertations

The earth sciences play an important role in engaging students in science and in science, technology, engineering and mathematics (STEM) disciplines, because of the integrative nature of the disciplines. It then becomes important for us to provide an engaging experience for students taking earth science courses, because it serves a dual purpose of possibly increasing new majors in the discipline and helping to create a science literate population.

Given that a majority of students in the larger introductory courses are non-majors, it behooves us to explore alternative engagement techniques and measure their efficacy in student engagement, which in turn can …

Digitally Manufactured Spatially Variant Photonic Crystals, Javier Jair Pazos

Open Access Theses & Dissertations

Metamaterials and photonic crystals are engineered composites that exhibit electromagnetic properties superior to those found in nature. They have been shown to produce novel and useful phenomena that allow extraordinary control over the electromagnetic field. One of these phenomena is self-collimation, an effect observed in photonic crystals in which a beam of light propagates without diffraction and is forced to flow in the direction of the crystal. Self-collimation however, like many of the mechanisms enabled through dispersion engineering, is effective in directions only along the principal axes of the lattice. To this effect, a general purpose synThesis procedure was developed …

Synthesis Of Peptide-Α-Phenylthioesters Using A Solid Support With A Photoreactive Nitroindoline Moiety, Andrew Pardo

Open Access Theses & Dissertations

Peptide-alpha-phenylthioesters are particularly reactive starting materials for Native Chemical Ligation. Here we present a new photochemical method for the synThesis of peptide-alpha-phenylthioesters under neutral reaction conditions with various C-terminal amino acids. The peptides were synthesized by Fmoc strategy on Sieber amide resin with a photoreactive nitroindoline linker. After cleavage of the photoreactive and fully protected peptide from the beads with dilute trifluoroacetic acid an auxiliary nucleophile such as N-hydroxybenzotriazole or N-hydroxysuccinimide is used to photochemically generate the activated peptide ester in situ. Then thiophenol is introduced in the dark. This new method enabled us to synthesize peptide-alpha-phenylthioesters up to 21 …

Water Recovery From Silica Saturated Ro Concentrate By The Concentrate Enhanced Reverse Osmosis Process, Gautam Patwardhan

Open Access Theses & Dissertations

Membrane fouling due to silica precipitation during reverse osmosis (RO) continues to be documented as the most common challenge in attaining stable continuous operation of RO systems across water treatment plants (1). Silica scale precipitation is time dependent and involves multiple steps leading to aqueous polymerization, condensation of polymers to form colloids, and deposition onto a solid surface (2). Exceeding the solubility of silica, widely considered to be in the range of 100-140 ppm, under a pH of 8 at 25 °C by various researchers, results in the precipitation of silica on the membranes, thereby limiting water recovery. Once the …

Public Social Network Sites And Social Recruiting, Abby Peters

Open Access Theses & Dissertations

Social network sites (SNSs) are an increasingly popular form of social media used by individuals and organizations. As these platforms continue to transform the way people communicate with one another, they are simultaneously revolutionizing the way individuals interact with organizations. Part of this dramatic change is apparent in the processes by which organizations are recruiting employees and job seekers are pursuing employment. To investigate these phenomena, I employed the diffusion of innovations theory in a SNS context to examine the relationship between organizations' use of their corporate career website and their use of SNSs as recruiting sources. Subsequently, I used …

Strongly Coupled Quark Matter: Chiral Symmetry Breaking In A Magnetic Field, And Eos In The Bec-Bec Crossover, Israel Portillo Vazquez

Open Access Theses & Dissertations

We explore chiral symmetry breaking in a magnetic field within a Nambu-Jona-Lasinio model of interacting massless quarks including tensor channels. The new interaction channels are opened up through Fierz identities due to the breaking of the rotational symmetry by the magnetic field. We demonstrate that the magnetic catalysis of chiral symmetry breaking leads to the generation of two independent condensates, the conventional chiral condensate and a spin-one condensate. While the chiral condensate generates a dynamical fermion mass, the spin-one condensate gives rise to a dynamical anomalous magnetic moment for the fermions. We also investigate the possibility of a crossover from …

Fast Algorithm For Finding Lattice Subspaces In Rn And Its Implementation, Andrew Martin Pownuk

Open Access Theses & Dissertations

There are known necessary and sufficient conditions for a subspace of Rm to be lattice-ordered. Let Y = {y1,…,ym} and yi are rows of the matrix X. A subspace ⟨X⟩, of linear space generated by the set X of n linearly independent positive vectors is lattice-ordered if and only the set X admits a fundamental set of indices I, which means that the subset YI ⊆ Y of vectors indexed by I is linearly independent, and every vector from Y\YI is a nonnegative linear combination of vectors form YI.

In economics it is possible to prove that the minimum-cost insured …

Residential Electricity Demand In Arkansas, Ileana M. Resendez

Open Access Theses & Dissertations

This study analyzes residential electricity demand in Arkansas. Explanatory variables utilized include real per capita income, residential electricity price, heating degree days, cooling degree days, and residential natural gas price. The results indicate that the income effect dominates the substitution effect given a real personal income increase and a decline in real electricity rates in the state of Arkansas during the period under study.

Effects Of Cerium Oxide Nanoparticles In Cereals: Insights Into The Toxicity Mechanisms And Macromolecular Modifications, Cyren Mendoza Rico

Open Access Theses & Dissertations

Despite the inundation of studies on the interaction of engineered nanomaterials (ENMs) with plants, investigations involving complete life cycle (i.e from seedling establishment to full maturity) are still lacking. Assessments on the nutritional value of plants cultivated to full maturity in ENMs-treated soil are also missing. Cerium oxide nanoparticles (nCeO2) have significant interactions with plants; however, there are no life cycle studies yet on their implications in cereals like rice (Oryza sativa L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). These cereals are globally important crops that support the economic activity, and nutritional and health needs of billions …

Design And Development Of Implantable And Remote Controlled Distraction Osteogenesis Device For Limb Lengthening Practice In Children, Mario Eduardo Rodriguez De La O

Open Access Theses & Dissertations

Recent technology improvements have been positively affecting medical industry in recent years since procedures and equipment are more precise and reliable. Nevertheless, there are still surgical procedures and medical devices that not fully address specific needs according to medical experts. One of those necessities is focused on options available for children patients when subjected to a surgical procedure named distraction osteogenesis. In general, distraction osteogenesis is performed when skeletal deformities need to be corrected or when bone lengthening is required, typically a mechanism is utilized to elongate bone at a controlled rate. The existing osteodistraction methods for limb lengthening and …

Three Essays On Social/Political Structures And Icts Use, Seungeui Ryu

Open Access Theses & Dissertations

My research identifies how social structures affect the use of the Internet and/or a mobile chat application and how the Internet impacts the political structure of a nation. In my first essay of the 3-essay Dissertation, I am designing three models based on social structure theory that are used to study the Internet and a popular mobile chat application's use by managers in South Korea, with the help of a survey instrument. In my first essay, the contribution is on i) testing a model of manager's personal behavior on Information and Communication Technology (ICT) use at the individual level involving …

Finite Density Qed At Strong Magnetic Field, Paul Lee Springsteen

Open Access Theses & Dissertations

In this Thesis we study the effect of a dense medium on the quantum properties of a relativistic electron-positron plasma under a magnetic field. From the calculation of the photon polarization operator depending on temperature, chemical potential, and the magnetic field; we study how the electric susceptibility of the strongly magnetized plasma is charged with temperature and density. In the same manner we study the dependence of the Debye mass with density. Then we investigated the phenomenon of magnetic catalysis of chiral symmetry breaking for a dense medium. We found that there exist a critical value of the chemical potential …

Permit Tool: Development Of An Algorithm To Determine Performance Life Of Hma Mixes In Texas, Luis Alberto Torres Escobedo

Open Access Theses & Dissertations

A number of hot mix asphalt (HMA) types, such as permeable friction course (PFC), stone mastic asphalt (SMA), performance design mixes and conventional dense graded mixes are currently used to construct or overlay Texas roads. One of the important inputs into current pavement design programs used by the Texas Department of Transportation (TxDOT) is the performance lives of HMA mixes. To determine the best mix type for a particular job or to analyze the performance of a mix or a road, a new system can be developed to rationally quantify the HMA mix performance. This system must have access to …

Homeomorphisms Between Pairs Of Genus Two Handlebodies And Separating Circles In Their Boundaries, Daniel Orlando Vazquez

Open Access Theses & Dissertations

A known result in low-dimensional topology is that every incompressible surface properly embedded in a genus two handlebody is boundary compressible. This result produces a pair consisting of a genus two handlebody and a separating curve in its boundary.

We study particular examples of genus two handlebodies and essential simple closed curves which separate their boundaries. The aim of this paper is to give our own construction of separating curves on the boundary of genus two handlebodies and compare them with previously studied pairs. These constructions involve taking 2n arcs on either side of a waist disk of a genus …

3d Printed Spatially Variant Anisotropic Metamaterials, Cesar Roman Garcia

Open Access Theses & Dissertations

The recent advancement in 3D printing has created a new way to design electronics and electromagnetic devices. This allows for a new breed of non-planar designs to be used, fully exploiting all three dimensions like never before. More functions can be fit into the same amount of space, products with novel form factors can be more easily manufactured, interconnects can be routed more smoothly, interfaces can be better implemented, electrical and mechanical functions can be comingled, and entirely new device paradigms will be invented. When departing from traditional planar topologies many new problems arise like signal integrity, crosstalk, noise, and …