Digital Commons Network^™

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

Open Access Theses & Dissertations

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

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

Open Access Theses & Dissertations

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

Acoustic Analysis Of The Allophones Of The Mid-Front Spanish Vowel /E/, Raquel Gonzalez De Anda

Open Access Theses & Dissertations

This thesis examines the Spanish phoneme /e/ and its open allophone(s). Current literature shows that there is no complete agreement with regards to the specific phonetic environments that trigger the opening of /e/, nor if "open" is the best term to describe the allophone(s). Examining /e/ allophones in Spanish monolinguals clarifies current literature inconsistencies; and therefore, creates a baseline for future studies related to this particular vowel. In this study, the speech of ten Spanish monolingual university students was recorded. Participants read a list of words that contained /e/ in certain phonetic contexts. Each instance of /e/ was acoustically analyzed …

Strengthening Cognitive Development In Minority Populations: A Study Of The Beneficial Effects Of Bilingualism, Marisela Gutierrez

Open Access Theses & Dissertations

The long-term goal of this research is to better understand and characterize the "bilingual advantage" so that educational and child care institutions begin to recognize and encourage the active use of two languages to strengthen cognitive development in minority populations. The present study is one of the first one to include a very large sample of well-defined "active bilinguals" who, by objective measures, were determined to be bilingual and determined to engage in language switching on a daily basis. Another goal was to manipulate and activate in the laboratory what might be referred to as the "switching benefit." One hundred …

The Influence Of Case-Specific Expert Testimony On Juror Sensitivity To Confession Evidence, Skye Alani Woestehoff

Open Access Theses & Dissertations

Research on the effect of expert testimony has resulted in incongruent findings. Expert testimony has been shown to lead to sensitivity, by educating participants about the evidence and facilitating the application of this knowledge, and skepticism, by causing jurors to distrust the evidence regardless of its quality. The current study explored the role of expert testimony in improving participants' evaluation of confession evidence. Data were collected from 352 students and 281 community members. Participants read a trial transcript that included a low-pressure, medium-pressure, or high-pressure interrogation. Participants also read expert testimony that was general, case-specific, or no testimony at all. …

Multiplicity Adjustments For Respecification Searches In Structural Equation Models, John Appiah Kubi

Open Access Theses & Dissertations

Structural Equation Modeling (SEM), as a statistical modeling technique, is one of the most comprehensive and flexible approaches to data analysis currently available. Its use has been increasing steadily over the past few decades. Generally, it refers to a family of

techniques that employs the analysis of covariance to establish relationships among a set of variables. It allows researchers (or users) to assess the adequacy of their hypothesized models with their sample data. Often times, in assessing their models, researchers are not

only interested in the overall fit of their model but they are also interested in knowing which proposed …

Evaluation Of Novel Backwashable Cartridge Filters: Efficacy And Sustainability, Michelle Brown

Open Access Theses & Dissertations

One of the important aspects of desalination pre–treatment is the removal of particles from feedwater. This is typically accomplished using a combination of gross filtration and cartridge filtration. Cartridge filters are typically single–use products, and their replacement can represent a significant portion of a desalination plant's operating budget. This research evaluated the performance of a new type of cartridge filter that is backwashable and aims to reduce the overall cost to desalination facilities and provide cleaner water. Two sets of filters were evaluated (in triplicate) with respect to particle removal efficiency and hydraulic efficiency. The initial set included four types …

Pressure And Heat Flux Effects On The Heat Transfer Characteristics Of Liquid Methane, Chance Paul Garcia

Open Access Theses & Dissertations

The heat transfer effects on liquid methane are investigated with the use of a carbo-thermal rig at the Center for Space Exploration Technology Research (cSETR) located at the University of Texas at El Paso (UTEP). The cSETR carbo-thermal rig design approach is presented along with the design of a methane condensing mobile unit (MCMU) to supply the laboratory and rig with liquid methane. The proposed research will generate useful insight in to heat transfer coefficient behavior, non-dimensional correlations, different flow conditions, varied inlet conditions, and varied heat flux for a subscale test article applicable to a regenerative cooled rocket engine …

A Case Study Towards Verification Of The Utility Of Analytical Models In Selecting Checkpoint Intervals, Michael Joseph Harney

Open Access Theses & Dissertations

As high performance computing (HPC) systems grow larger, with increasing numbers of components, failures become more common. Codes that utilize large numbers of nodes and run for long periods of time must take such failures into account and adopt fault tolerance mechanisms to avoid loss of computation and, thus, system utilization. One of those mechanisms is checkpoint/restart. Although analytical models exist to guide users in the selection of an appropriate checkpoint interval, these models are based on assumptions that may not always be true. This thesis examines some of these assumptions, in particular, the consistency of parameters like Mean Time …

Anasic Design And Test Methodology For An Undergraduate Design And Fabrication Project, Arun Joseph Kurian

Open Access Theses & Dissertations

During the 1990's the main focus of chip design methodologies was on the timings and area constraints. Power consumption was considered significant only after a drastic increase of device densities from 130nm on as well as dramatic increases in sub threshold leakage. As technology advanced from 130nm to 90nm and below there was a significant increase in leakage current due to lower threshold voltage and the influence of the deep submicron effects. High power consumption causes different problems such as increasing the cost of the product, reducing the reliability, reducing the battery life among others. Therefore EDA tools were designed …

An Intra-Individual Event-Related Potential-Based Concealed Attitude Test, David R. Herring

Open Access Theses & Dissertations

The evaluative oddball is an implicit measure for detecting (concealed) attitudes. In evaluative oddball studies, low occurrence stimuli such as negative pictures are presented among high occurrence context stimuli such as positive pictures. Late positive potentials (LPPs) of the event-related potential (ERP) are larger to evaluatively incongruent stimuli such as negatives compared to congruent stimuli such as positives with the context (e.g., positives). In prior evaluative oddball paradigms, this evaluative congruity effect of the LPP was reduced when participants concealed compared to truthfully reported attitudes. Because prior evaluative oddballs have been focused on the group level analysis, it has been …

Effects Of Positive Distortion Instructions On The Factor Structure Of Socially Desirable Responding Scales, Corina Mendoza

Open Access Theses & Dissertations

Socially desirable responding (SDR) is the manifestation of an individual's desire to represent him or herself in a positive light on a self-report questionnaire. Two distinct types of questionnaire scales are commonly used to identify individuals who have engaged in SDR: Impression Management (IM) and Self-Deceptive Enhancement (SDE) scales. In the present study, 653 undergraduate students completed four IM scales, three SDE scales, and two brief questionnaires measuring the Big Five personality factors. Participants were randomly assigned to either a Control condition, in which they were instructed to complete the questionnaires according to standard instructions, or a Positive Distortion (PD) …

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

Open Access Theses & Dissertations

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

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

Open Access Theses & Dissertations

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

Organic Photovoltaics: A Charge Transfer Perspective In The Study Of Donor-Acceptor Systems, Marco Olguin

Open Access Theses & Dissertations

The present research involves the study of donor-acceptor (D/A) dyad complexes from a charge transfer energy perspective. The aim is to provide insight and predictive understanding into the charge transfer processes of the molecular-level components in donor-acceptor based organic solar cells using computational methods to describe photochemical processes at the quantum mechanical level within the Density Functional Theory (DFT) approximation. Predictive understanding is anchored in reproducing experimental results, wherein the present work a perturbative excited-state DFT method is described in detail and shown to give Charge Transfer (CT) energies in excellent agreement with benchmark experimental data. With an accurate excited …

Efficient, Scalable, Parallel, Matrix-Matrix Multiplication, Enrique Portillo

Open Access Theses & Dissertations

For the past decade, power/energy consumption has become a limiting factor for large-scale and embedded High Performance Computing (HPC) systems. This is especially true for systems that include accelerators, e.g., high-end computing devices, such as Graphics Processing Units (GPUs), with terascale computing capabilities and high power draws that greatly surpass that of multi-core CPUs. Accordingly, improving the node-level power/energy efficiency of an application can have a direct and positive impact on both classes of HPC systems.

The research reported in this thesis explores the use of software techniques to enhance the execution-time and power-consumption performance of applications executed on a …

Preparing Teachers For Use Of Impact Activities: An Exploratory Study, Jeremy Lee Ramirez

Open Access Theses & Dissertations

The iMPaCT project team has developed three modules of activities that use programming on TI-83/84 calculators as a means to engage students to explore foundational concepts in Algebra I. The developers conducted a 3-day summer Professional Development Program (PDP) for teachers to become familiar with the objectives, pedagogy, assessments, and resources of the three modules of iMPaCT activities. I have collected and analyzed various forms of data such as videotapes of workshop sessions, teachers' written work and a pre-post assessment. The purpose of this study is to provide the program coordinators with information about the PDP for planning of future …

The Development Of Self-Supported Electromechanical Structures Using Fused Deposition Modeling, Jorge Ramos-Almeida

Open Access Theses & Dissertations

Recent research has focused on the fabrication freedom of 3D printing to create not only conceptual models but also final end-use products. In the last decade, several research groups have reported embedding electronic components and electrical interconnects into 3D printed structures during process interruptions; however, to date there is an absence of fabricated devices with electromechanical functionality for parts fabricated in a single Additive Manufacturing (AM) build sequence.

The focus of this research is the use of Fused Deposition Modeling (FDM) to manufacture a self-supported electromechanical motor. FDM is an AM process capable of building parts in a layer-by-layer fashion. …

Asynchronous Logic Design With Increased Fault Tolerance And Optimized For Subthreshold Operation, Ivan Santos

Open Access Theses & Dissertations

Synchronization has always been an essential feature in electronic circuits, in which functionality is achieved by an appropriate flow of data with respect to time. An ideal concept of logic design would require every operation to happen instantly; however, the application of this principle to electronics is governed by the laws of physics, which influence the time to execute a process. In fact, the speed at which a microprocessor can perform logic operations is determined by the time that charging and discharging capacitive loads requires, and the time that electric signals spend when traveling through the circuitry. Consequently, the variation …

Propagation Of Interval And Probabilistic Uncertainty In Cyberinfrastructure-Related Data Processing And Data Fusion, Christian Servin

Open Access Theses & Dissertations

Data uncertainty affects the results of data processing. So, it is necessary to find out how the data uncertainty propagates into the uncertainty of the results of data processing. This problem is especially important when cyberinfrastructure enables us to process large amounts of heterogeneous data. In the ideal world, we should have an accurate description of data uncertainty, and well-justified efficient algorithms to propagate this uncertainty. In practice, we are often not yet in this ideal situation: the description of uncertainty is often only approximate, and the algorithms for uncertainty propagation are often not well-justified and not very computationally efficient. …

Benefits Of Baby Sign On Cognitive Development In Infants, Clarissa Navedo

Open Access Theses & Dissertations

Research in the area of baby sign language has increased dramatically over the past several years, however there is still a lack of research regarding baby signs effects on typical infant development, specifically in the area of cognition. The hypothesis of this study was that instruction of baby sign would be correlated with a significant increase in the development of cognition and language acquisition for infant participants. This study provided a five-week instructional course on baby sign for parents/caregivers to implement with their typically developing infants (n=11). The course provided instruction of baby signs, methods of implementation and encouragement to …

Model Fusion: A New Approach To Processing Heterogeneous Data, Omar Ochoa

Open Access Theses & Dissertations

In many practical situations, it is necessary to extract

information from data of different types. For example, in geosciences, several sources of data can be used to determine the interior structure of the earth: the first arriving waves from earthquakes and from man-made sources, measurements of the earth's gravity field, measurements of the dispersion of surface waves generated by earthquakes, etc. At present, most existing data processing techniques deal only with data of one type.

A joint use of all the information derived from multiple types of data sources is an important theoretical and practical challenge. Such a joint use …

Carbon Emissions From Soil Respiration In The Northern Chihuahuan Desert Shrubland, Anna Cristina Ortiz

Open Access Theses & Dissertations

The United States Department of Agriculture's Jornada Experimental Range (JER), is located in the northern Chihuahuan Desert in southern New Mexico and historically functioned as an experimental rangeland for cattle grazing. Historical grazing in the US Southwest has been identified as a leading, but not the sole, factor that has led to the conversion of pristine grasslands to shrublands, such has been the case on the JER. The estimated increased variability in precipitation intensity and frequency that is predicted to occur with climate warming will likely affect ecosystem responses from ecological processes including primary productivity, microbial decomposition, and thus respiration. …

(Re)Mapping The Rhetorical Situation: Toward A Transactional Networked Ecology, Ramesh Kumar Pokharel

Open Access Theses & Dissertations

The existing theories of the rhetorical situation that focus on and around Bitzer's theory define the rhetorical situation as something "real," "genuine," "objective" based on historic reality. I believe that this modernist containment to perceive the rhetorical situation as fixed entities limit our understanding about it in a broader sense, because it cannot capture the changed meaning that naturally exists with the impact of new media and technology. With the advent of new media and technology, the notion of rhetorical situation also has changed and thus there is an exigence of a new theory of the rhetorical situations that better …

3d Printed Impedance Elements By Micro-Dispensing, Ubaldo Robles Dominguez

Open Access Theses & Dissertations

Micro-dispensing allows electric circuits to be "3D printed," which can be used to give 3D printed systems electronic and electromagnetic functionality. The focus of this thesis is using micro-dispensing to fabricate capacitors and inductors. 3D printed impedance elements are capable of being more easily embedded, can be used to create structural electronics, and will have extensive applications in antennas, metamaterials, frequency selective surfaces, and more. This is the first known effort to print and measure impedance elements by micro-dispensing which holds great potential for manufacturing multi-material devices.

Developing A Sustainable Ecotourism Foundation In Indonesian National Parks Using Cross-Cultural Adaptation And Communication Framing, Adriana Salas

Open Access Theses & Dissertations

Previous research on ecotourism in Southeast Asia has focused on its positive and negative effects for conservation. However, the focus in this particular study is to look at what it takes to run a successful ecotourism site in four diverse areas in Indonesia using communication elements like cross-cultural adaptation and communication framing. Communication should be used as a baseline for a successful site and should be used as the most useful tool to address issues and challenges in ecotourism project development.

A successful ecotourism site must carefully look at how their ideas and programs are framed. Ecotourism must also create …

Event Related Potential Changes In A Two-Stimulus Auditory Oddball Task In Concussed College Athletes: A Linguistic Component, Paola G. Sanchez

Open Access Theses & Dissertations

"Return to Play" decisions are done based on cognitive-communicative testing and clinical assessments; concussed athletes may benefit from electrophysiological testing for a more accurate representation of their recovery. The purpose of this study is to investigate the electrophysiological performance post-concussion analyzing the attentional differences using the traditional "oddball" paradigm with a CV linguistic component. Participants for this study were 6 male college athletes with a history of concussion and 10 participants with no history of concussion (controls). Athletes were evaluated using event-related potentials (ERPs) that were recorded during a consonant-vowel (CV) auditory oddball task. Both the P300a and P300b components …

A Convex Optimization Algorithm For Sparse Representation And Applications In Classification Problems, Reinaldo Sanchez Arias

Open Access Theses & Dissertations

In pattern recognition and machine learning, a classification problem refers to finding an algorithm for assigning a given input data into one of several categories. Many natural signals are sparse or compressible in the sense that they have short representations when expressed in a suitable basis. Motivated by the recent successful development of algorithms for sparse signal recovery, we apply the selective nature of sparse representation to perform classification. Any test sample is represented in an overcomplete dictionary with the training sample as base elements. A given test sample can be expressed as a linear combination of only those training …

The Impact Of Baby Sign On The Development Of Pragmatic Skills In Typically Developing Children, Lyna Marie Sullivan

Open Access Theses & Dissertations

The purpose of this study was to determine the impact of Baby Sign on the pragmatic development of typically developing children. The participants for the study were 11 typically developing children. A one group pretest posttest case study design was used to evaluate the impact of baby sign. Prior to parents and caregivers attending a 5 week course on baby sign language, each child was administered the Developmental Assessment of Young Children (DAYC). Although, measurements were taken of the child's social, cognitive, physical, adaptive, and communication skills, standard scores of only the social subtests from the pretest to the posttest …

Effects Of Augmentative And Alternative Device On Echolalia In Autism, Cynthia Valenzuela

Open Access Theses & Dissertations

This study was a systematic replication of Mueller and Forbes (n.d.), which evaluated the effects of a high-tech and low-tech augmentative alternative communication (AAC) device on reducing echolalia in a verbal child with autism during conversational speech. The participant for this study was a verbal eleven-year male, who was diagnosed with autism prior to the study. A single subject alternating treatment research design was used to evaluate the effect of a high-tech speech generating AAC device (Proloquo2go) on echolalia. The participant was seen periodically twice a week for two months and periodically for one month. A functional analysis(Prizant & Rydell, …