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 …

Why Ricker Wavelets Are Successful In Processing Seismic Data: Towards A Theoretical Explanation, Afshin Gholamy Salehabady

Open Access Theses & Dissertations

In many engineering applications ranging from engineering seismology to petroleum engineering and civil engineering, processing seismic data plays a key role. In processing seismic data, it turns out to be very efficient to describe the signal's spectrum as a linear combination of Ricker wavelet spectra.

In this Thesis, we provide a possible theoretical explanation for this empirical efficiency. Specifically, signal propagation through several layers is discussed, and it is shown that the Ricker wavelet is the simplest non-trivial solution for the corresponding data processing problem, under the condition that the described properties of the approximation family are satisfied.

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 …

Characterizing Cryogenic Propellant Flow Behavior Through A Cavitating Venturi In Comparison To Alternative Flow Control Mechanisms, Marjorie Adele Ingle

Open Access Theses & Dissertations

The work detailed is an investigation of the use of a cavitating venturi as both a flow control and metering device. This was achieved through the combination of actual experimentation and numerical modeling of the fluid behavior of both liquid water and liquid methane as it passes through the test article designed, developed, and validated here within this study. The discharge coefficient of the cavitating venturi was determined through weigh flow calibration testing to determine an average mass flow rate. Turbine flow meter flow rate readings were used as a point of comparison and the discharge coefficient was computed. The …

Design Of Three Different Particle Size Distributions In Silver Paste Through Computer Simulation For Higher Electrical Conductivity, Kyungdeok Jang

Open Access Theses & Dissertations

In the field of printed electronics technology, researchers have tried to print highly conductive electrodes with fine width and height in order to manufacture high performance devices.

The purpose of this research is to print particle monolayer silver patterns which have better electrical conductivity than existing ones. The key idea of this experiment is to analyze silver inks with different sized particles. Let us consider a particle monolayer pattern printed with silver ink consisting of mono-sized particles. Inside of the pattern, there are some vacant spaces between the particles, which can lead to low electrical conductivity and discontinuity of the …

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 …

2014-2015 Graduate Catalog, Morehead State University

Morehead State Catalog Archive

2014-2015 graduate catalog for Morehead State University.

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 …

2014-2015 Undergraduate Catalog, Morehead State University

Morehead State Catalog Archive

2014-2015 undergraduate catalog for Morehead State University.

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 …

Art And Hyperreality, Alfredo Martin-Perez

Open Access Theses & Dissertations

My Thesis pertains to philosophy of art. Its main purpose is a reconsideration of the notion of art as a response to claims stating the end of art, as in the case of the writings on hyperreality, stating that the transformation of reality, has resulted in a world that is permeated with a virtual reality that replaces traditional schemas for ways of living in the world, that valued the originality of art.

In the setting up of the subject, I will briefly mention descriptions of both reality and hyperreality, and the developments in art throughout the modern, and post modern …

Another Colonialist Tool?, Aaron Barlow

Publications and Research

"the student enrolled in an xMOOC, I believe, is in much the same position as both the student before the teaching machine and the colonized individual. She or he is forced to deal with foreign assumptions having little to do with the reality of the learner or the colonized."

Neighbor Discovery Message Hold Times For Mobile Ad Hoc Networks, Joshua Lee Mccartney

Open Access Theses & Dissertations

We present the results of an experimental study designed to understand the impact of neighbor discovery message hold times on network performance measures for a mobile ad hoc network. A physical testbed of pseudo-mobile nodes using the OLSR routing protocol was used for our experiments. We found statistically significant evidence to suggest that setting the neighbor discovery message hold times close to the neighbor discovery message interval time results in the best overall network performance.

Super Resolution Pump-Probe Microscopy With Point Spread Function Engineering, Farzaneh Mohajerani

Open Access Theses & Dissertations

Since the last decade, new techniques have made optical microscopy break the diffraction barrier of resolution where all of them are based on molecular fluorescence. Among them, stimulated emission depletion microscopy (STED) has reached less than 25 nm resolution by engineering the point spread function. However, the existing obstacles associated with fluorescence tagging makes it desirable to achieve label-free imaging. Recently the pump-probe method has made it possible to obtain image contrast from molecular absorption and vibration signatures that do not depend on fluorescence. We introduce Super Resolution Pump-Probe Microscopy (SRPPM), in which we combine both PSF engineering method and …

An Exploration Of Self-Management Support In The Context Of Palliative Nursing: A Modified Concept Analysis, Bridget Johnson, Liz Rogerson, Jurate Macijauskiene, Aurelija Blaževičienė, Patricia Cholewka

Publications and Research

Background
The role of self-management is often ambiguous, yet, it is an important area in clinical practice for palliative nurses. A clear conceptual understanding, however, of what it represents is lacking.

Method
This paper reports an analysis of the concept of self-management support in palliative nursing. Avant and Walker's method was used to guide this concept analysis. A search of electronic databases (1990–2013), use of internet search engines and supplementary hand searching produced an international data set of reviews, empirical research, editorials, protocols and guidelines.

Results
Based on the analysis self-management support in palliative nursing has been defined as assessing, …

Fabrication Of A Nickel-Based Superalloy In Electron Beam Melting And Process Improvements Using Thermal Feedback From A Multi-Wavelength Pyrometer, Jonathan Minjares

Open Access Theses & Dissertations

The focus of this research was to fabricate parts composed of a nickel-based superalloy containing high levels of aluminum and titanium (NSAT) by using electron beam melting (EBM) additive manufacturing (AM) technology and utilizing thermal feedback from a multi-wavelength pyrometer to perform process improvements leading to near defect-free parts. EBM is an AM technology that utilizes metal powder to fabricate parts in layer-by-layer manner. A multi-wavelength pyrometer was implemented in an Arcam S12 (Arcam AB, Sweden) EBM system to observe and record surface temperatures throughout fabrication. Temperature data from the EBM system and the multi-wavelength pyrometer were graphed using MATLAB …

Design And Evaluation Of A High Temperature/Pressure Supercritical Carbon Dioxide Direct Tubular Receiver For Concentrating Solar Power Applications, Jesus Daniel Ortega

Open Access Theses & Dissertations

This work focuses on the development of a solar power thermal receiver for a supercritical-carbon dioxide (sCO2), Brayton power-cycle to produce ~1 MWe. Closed-loop sCO2 Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. High temperatures (923 - 973 K) and pressures (20 - 25 MPa) are required in the solar receiver to achieve thermal efficiencies of ~50%, making concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. In this study, the CSP receiver is required to achieve an outlet temperature of …

Views From A Community College On The U.S.- Mexico Border: Mexican/Mexican-American Postsecondary Students' Perceptions Of K-16 Mathematics Education, Carlos Ruben Paez Paez

Open Access Theses & Dissertations

The purpose of this study was to investigate Mexican/Mexican-American postsecondary students' perceptions and experiences of mathematics instruction in U.S. formal education (K-16). Framed by critical race theory and using a grounded theory approach, this inquiry was conceptualized within the framework of the literature on academic disparities in achievement in mathematics between Mexican American students and other student populations in U.S. schools, highlighting students' perceptions and student voice. Qualitative data were collected through interviews and surveys from five postsecondary students who voluntarily participated in the study. Data analysis used the constant comparative method, a key element of grounded theory methodology (Glaser, …

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 …

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 …

Master's In Electrical Engineering, Ricardo Xavier Rodriguez

Open Access Theses & Dissertations

This project is a focus on characterizing the process for actualizing three dimensional structures out of a carbon nanostructure composite via a direct print additive manufacturing process. Manufacturing parts additively enables for realization of geometrically complex shapes that often times cannot be manufactured any other way. The specificity of a material's properties have to be such, that the processing method can precisely place and bond material to itself in a highly repeatable manner. Commercial materials for additive manufacturing are have been optimized with these goals in mind and, therefore, often times lack the rigor and robustness for many applications.

The …

Characterization Of High-Purity Niobium Structures Fabricated Using The Electron Beam Melting Process, Cesar Adrian Terrazas

Open Access Theses & Dissertations

Additive Manufacturing (AM) refers to the varied set of technologies utilized for the fabrication of complex 3D components from digital data in a layer-by-layer fashion. The use of these technologies promises to revolutionize the manufacturing industry. The electron beam melting (EBM) process has been utilized for the fabrication of fully dense near-net-shape components from various metallic materials. This process, catalogued as a powder bed fusion technology, consists of the deposition of thin layers (50 - 120µm) of metallic powder particles which are fused by the use of a high energy electron beam and has been commercialized by Swedish company Arcam …

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 …

An Experimental Investigation On Liquid Methane Convection And Boiling In Rocket Engine Cooling Channels, Abraham Trujillo

Open Access Theses & Dissertations

In the past decades, interest in developing hydrocarbon-fueled rocket engines for deep spaceflight missions has continued to grow. In particular, liquid methane (LCH4) has been of interest due to the weight efficiency, storage, and handling advantages it offers over several currently used propellants. Deep space exploration requires reusable, long life rocket engines. Due to the high temperatures reached during combustion, the life of an engine is significantly impacted by the cooling system's efficiency. Regenerative (regen) cooling is presented as a viable alternative to common cooling methods such as film and dump cooling since it provides improved engine efficiency. Due to …

Nanometric Structure-Property Relationship In Hafnium Oxide Thin Films Made By Sputter-Deposition, Mirella Vargas

Open Access Theses & Dissertations

Hafnium oxide (HfO2) is technologically an important material, which exhibits a unique set of properties such as a high dielectric constant (k~25) and wide band gap (~5.7 eV) which make this material attractive in the fields of microelectronics and optoelectronics. HfO2 has become the leading candidate to replace SiO2 dielectrics in gate oxides due to a higher permittivity and reportedly lower electron tunneling effects. HfO2 exhibits various polymorphs; the thermodynamic stability and phase existence depends on the temperature and pressure conditions. In addition, the controlled growth and manipulation of specific HfO2 crystal structures at the nanoscale dimensions is the driving …

Modeling And Simulation Of A Lead-Free Active Structural Fiber For Multifunctional Composites, Linda Vera

Open Access Theses & Dissertations

Piezoelectric materials are widely used in a many areas of science and technology due to their unique electromechanical properties. The transformation of mechanical energy into electrical energy and vice versa caused by the piezoelectric effect has led to the development of piezoelectric sensor devices and actuators used in accelerometers, pressure and vibration meters, micropositioning devices, ultrasound generators, structural health monitoring, etc.

The most used piezoelectric material to this day is lead zirconate titanate PbZrO3-PbTiO3 (PZT) because of its high piezoelectric coefficient and Curie temperature, which allows it to be used in a more wide variety of applications. However, the commercial …

An Econometric Approach For Modeling Population Change In Doña Ana County, New Mexico, Diana Villavicencio

Open Access Theses & Dissertations

An econometric model using time series analysis techniques is used to model and forecast population changes in Doña Ana County, New Mexico. The model focuses on the interplay between economic and demographic variables. Individual, cointegrated equations are generated to account for the components of population change. Significant results were found in the components of population change - births, deaths, net domestic and net international migration. Birth and death equations prove easier to model because of stable changes from period to period in relation to the nation and income levels. Net migration equations were more difficult to model as economic conditions, …

Variable Selection For Cox Proportional Hazards Models Via Subtle Uprooting, Chalani S. Wijayasinghe

Open Access Theses & Dissertations

Cox proportional hazards model (Cox PH model) is heavily used in survival analysis to assess the importance of various covariates on the survival times of individuals or objects through the hazard function. This study suggests a new variables selection method for Cox PH models, under the title 'Subtle uprooting', that does variable selection and model estimation for Cox proportional hazards (PH) models simultaneously.

There are subset selection methods and shrinkage selection methods suggested in the context of Cox PH model. However the subset selection methods become infeasible in higher dimensions and the available shrinkage methods need tuning of parameters making …

Perspectives On The Nature Of Science From A Group Of Students Attending Predominantly Hispanic West Texas High School, Cameron King Wilson

Open Access Theses & Dissertations

The United States is falling far behind the rest of the world in its ability to fulfill its needs for qualified workers in Science, Technology, Engineering, and Mathematics (STEM) fields. The Hispanic population is now the largest minority in the United States but is proportionally underrepresented in the STEM fields today. It is shown that students who have a good understanding of the Nature of Science (NOS) are far more likely to be interested in science which may lead to an interest in careers in STEM fields. There is very little if any research identifying Hispanic high school students' view …

The Interfacial Fracture Of Bonded Materials And Composites, Kai Zhao

Open Access Theses & Dissertations

Adhesive bonding and composite materials have been widely used in manufacturing industry. Failure results from the weakest link in a structure and this is often the interface between two materials. In case of composites, it becomes the fiber and matrix interface. In case of bonded polymers, the bonding line is the interface. This Dissertation is focused on the interfacial fracture of bonded materials and composites. First, a systematic experimental investigation on adhesive bonding strengths of polymer/polymer and polymer/metal joints was conducted and the experimental results were compared with other researchers' work. Then, a modified short-beam shear approach is developed to …