Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

North Carolina Agricultural and Technical State University

Dissertations

2013

Discipline
Keyword

Articles 1 - 18 of 18

Full-Text Articles in Engineering

Quantitative Analyses Of Acceptable Noise Level For Air Conduction Listening, Bankole K. Fasanya Jan 2013

Quantitative Analyses Of Acceptable Noise Level For Air Conduction Listening, Bankole K. Fasanya

Dissertations

This study was conducted to develop quantitative models for Acceptable Noise Level (ANL) under air conduction (AC) listening conditions. Experimental results on the effects of frequency bandwidths on ANL under two listening conditions involving earphones and loudspeaker (sound field) with high and low frequencies and babble noise and white noise revealed: (a) there are statistically significant interactions among the background noise types, the background noise frequency bandwidths and signal source; (b) background noise and noise frequency bandwidths have effects on listener discriminability bias toward the noise and the signal intensity; (c) different listening conditions had different ANL thresholds; and (d) …

Go to article

A Neurophysiologic Study Of Visual Fatigue In Stereoscopic Related Displays, Hanniebey Dolphyne Nutung-Wiyor Jan 2013

A Neurophysiologic Study Of Visual Fatigue In Stereoscopic Related Displays, Hanniebey Dolphyne Nutung-Wiyor

Dissertations

Two tasks were investigated in this study. The first study investigated the effects of alignment display errors on visual fatigue. The experiment revealed the following conclusive results: First, EEG data suggested the possibility of cognitively-induced time compensation changes due to a corresponding effect in real-time brain activity by the eyes trying to compensate for the alignment. The magnification difference error showed more significant effects on all EEG band waves, which were indications of likely visual fatigue as shown by the prevalence of simulator sickness questionnaire (SSQ) increases across all task levels. Vertical shift errors were observed to be prevalent in …

Go to article

A Decision Support System For The Intelligence Satellite Analyst, Gi Yeon Park Jan 2013

A Decision Support System For The Intelligence Satellite Analyst, Gi Yeon Park

Dissertations

The study developed a decision support system known as Visual Analytic Cognitive Model (VACOM) to support the Intelligence Analyst (IA) in satellite information processing task within a Geospatial Intelligence (GEOINT) domain. As a visual analytics, VACOM contains the image processing algorithms, a cognitive network of the IA mental model, and a Bayesian belief model for satellite information processing. A cognitive analysis tool helps to identify eight knowledge levels in a satellite information processing. These are, spatial, prototypical, contextual, temporal, semantic, pragmatic, intentional, and inferential knowledge levels, respectively. A cognitive network was developed for each knowledge level with data input from …

Go to article

Computational Material Modeling For Mechanical Properties Prediction And A Methodology For Mie Gruneisen Equation Of State Characterization Via Molecular/Nano Scale Cementitious Material Constituents, Ahmed Mohamed Jan 2013

Computational Material Modeling For Mechanical Properties Prediction And A Methodology For Mie Gruneisen Equation Of State Characterization Via Molecular/Nano Scale Cementitious Material Constituents, Ahmed Mohamed

Dissertations

Cementitious materials have complex hierarchical structures with random features that range from nanometer (nm) to millimeter (mm) scale. Processes occurring at the nanometer scale affect the performance at larger length scales. The present work employs molecular dynamics (MD) simulations as the computational modeling methodology to predict mechanical properties for both hydrated and unhydrated cementitious materials at the molecular/nano scale level. A detailed study on the effect of increasing MD simulation cell size, dynamics time duration on the predicted mechanical properties was performed. Further studies focused on understanding the effect of higher thermodynamic pressure states on predicted …

Go to article

Fatigue Characterization Of Fire Resistant Syntactic Foam Core Material, Mohammad Mynul Hossain Jan 2013

Fatigue Characterization Of Fire Resistant Syntactic Foam Core Material, Mohammad Mynul Hossain

Dissertations

Eco-Core is a fire resistant material for sandwich structural application; it was developed at NC A&T State University. The Eco-Core is made of very small volume of phenolic resin and large volume of flyash by a syntactic process. The process development, static mechanical and fracture, fire and toxicity safety and water absorption properties and the design of sandwich structural panels with Eco-Core was established and published in the literature. One of the important properties is needed for application in transportation vehicles is the fatigue performance under different stress states. Fatigue data are not available even for general syntactic foams. The …

Go to article

Multiphase Hydrodynamics In Steady And Pulse Jet Mixing Systems, Ibraheem R. Muhammad Jan 2013

Multiphase Hydrodynamics In Steady And Pulse Jet Mixing Systems, Ibraheem R. Muhammad

Dissertations

The goal of the present study is to evaluate the mixing performance of jet mixers in both liquid and solid-liquid mixing processes. Jet mixers have been studied for decades for its uses in liquid blending and solid-liquid mixing applications. In solid suspension processes, jet mixers can be just as useful if not more useful than conventional impeller mixers. However, there is a lack of phenomenological models that exist. The erosion and subsequent suspension of solids beds, as well as the suspension of a low concentration of solid particles must be better understood. The specific objectives were to develop analytical, experimental …

Go to article

Modeling Decision Making In Trauma Centers From The Standpoint Of Complex Adaptive Systems, Castanon De Policarpo Jan 2013

Modeling Decision Making In Trauma Centers From The Standpoint Of Complex Adaptive Systems, Castanon De Policarpo

Dissertations

This research examines complex clinical decision-making processes in trauma center units of hospitals in terms of the impact of complexity on the medical team involved in the trauma event. The science of complex adaptive systems together with human judgment theories provide important concepts and tools for responding to health care challenges in this century and beyond. Clinical decision-makers in trauma centers are placed in urgent and anxious situations that are increasingly complex, making decision-making and problem-solving processes multifaceted. Under stressful circumstances, physicians must derive their decision-making schemas (―internal models‖ or ―mental models‖) without the benefits of judicious identification, evaluation, and/or …

Go to article

Assessment Of Neck And Shoulder Muscle Coactivations And The Effect On The Musculoskeletal System, Regina Derria Pope-Ford Jan 2013

Assessment Of Neck And Shoulder Muscle Coactivations And The Effect On The Musculoskeletal System, Regina Derria Pope-Ford

Dissertations

Musculoskeletal disorders (MSDs) constitute one of the most important occupational health issues in healthcare workers who are susceptible to upper extremity disorders. Yet MSDs in the healthcare professions have not been studied extensively beyond the lower back. The focus population for this research is the field of dentistry where neck and shoulder disorders have been documented to have a high prevalence. Though quantitative data has been collected, many prior studies have focused on self-reported information. The goal of this research is to provide insight into the inter-relationship of muscles in the upper extremities. One way to accomplish this is to …

Go to article

Monitoring Damage Initiation And Growth In Composite Structures By Acoustic Emission Method, Kassahun Mekonnen Asamene Jan 2013

Monitoring Damage Initiation And Growth In Composite Structures By Acoustic Emission Method, Kassahun Mekonnen Asamene

Dissertations

In this dissertation, acoustic emission technique is examined as candidate for monitoring the integrity of polymer matrix structural members. Acoustic emission technique has so far been largely limited to laboratory tests and field applications have been mostly limited to qualification tests of aerospace structures. The lack of quantitative indications of damage in composite structural members associated with the complex nature of damage in these materials has been a limiting factor. Generally, a number of failure modes operate simultaneously at a site of damage, and each of these failure modes generates a different type of acoustic emission signal. In addition, issues …

Go to article

A Mathematical Modeling Framework For Phlebotomist Scheduling And Blood Draw Assignments In Laboratory Medicine, Laquanda T. Leaven Jan 2013

A Mathematical Modeling Framework For Phlebotomist Scheduling And Blood Draw Assignments In Laboratory Medicine, Laquanda T. Leaven

Dissertations

Laboratory services in healthcare delivery systems play a vital role in inpatient care. Studies have shown that laboratory data affects approximately 65% of the most critical decisions on admission, discharge, and medication. Laboratory testing accounts for approximately 10% of hospital billing. Reducing laboratory costs would contribute to reducing total healthcare cost, which is one of the major goals for the U.S. healthcare delivery system. This research focuses on improving the performance of the hospital laboratory in a large hospital system. The intention of this study is to identify and then optimize the most critical stage to improve the entire laboratory …

Go to article

Fitness Proportionate Niching: Harnessing The Power Of Evolutionary Algorithms For Evolving Cooperative Populations And Dynamic Clustering, Abrham Tibebu Workineh Jan 2013

Fitness Proportionate Niching: Harnessing The Power Of Evolutionary Algorithms For Evolving Cooperative Populations And Dynamic Clustering, Abrham Tibebu Workineh

Dissertations

Evolutionary algorithms work on the notion of "best fit will survive" criteria. This makes evolving a cooperative and diverse population in a competing environment via evolutionary algorithms a challenging task. Analogies to species interactions in natural ecological systems have been used to develop methods for maintaining diversity in a population. One such area that mimics species interactions in natural systems is the use of niching. Niching methods extend the application of EAs to areas that seeks to embrace multiple solutions to a given problem. The conventional fitness sharing technique has limitations when the multimodal fitness landscape has unequal peaks. Higher …

Go to article

An Augmented Interaction Strategy For Designing Human-Machine Interfaces For Hydraulic Excavators, Joseph Akyeampong Jan 2013

An Augmented Interaction Strategy For Designing Human-Machine Interfaces For Hydraulic Excavators, Joseph Akyeampong

Dissertations

Lack of adequate information feedback and work visibility, and fatigue due to repetition have been identified as the major usability gaps in the human-machine interface (HMI) design of modern hydraulic excavators that subject operators to undue mental and physical workload, resulting in poor performance. To address these gaps, this work proposed an innovative interaction strategy, termed “augmented interaction”, for enhancing the usability of the hydraulic excavator. Augmented interaction involves the embodiment of heads-up display and coordinated control schemes into an efficient, effective and safe HMI. Augmented interaction was demonstrated using a framework consisting of three phases: Design, Implementation/Visualization, and Evaluation …

Go to article

Effect Of Doping On Β-Tricalcium Phosphate Bioresorbable Bulk Material And Thin Film Coatings, Suhaila Abdalla Jan 2013

Effect Of Doping On Β-Tricalcium Phosphate Bioresorbable Bulk Material And Thin Film Coatings, Suhaila Abdalla

Dissertations

Magnesium has emerged as a revolutionary biodegradable metal for use as an orthopedic material, it has several advantages over the permanent metallic materials currently in use, including eliminating the effects of stress shielding, improving biocompatibility and degradation properties, thus removing the requirement of a second surgery for implant removal. Due to the rapid degradation of magnesium, it is necessary to control the corrosion rates of the materials to match the rates of bone healing. This dissertation reports on the effect of doping on the properties of β-tricalcium phosphate (β-TCP). It also reports on its application as a thin film coating …

Go to article

Tropical Cyclone Intensity Estimation Using Temporal And Spatial Features From Satellite Data, Gholamreza Fetanat Haghighi Jan 2013

Tropical Cyclone Intensity Estimation Using Temporal And Spatial Features From Satellite Data, Gholamreza Fetanat Haghighi

Dissertations

Accurate intensity estimation of tropical cyclones (TC) is an important topic of research due to its economic impact and public safety concerns. An accurate measure of the current wind strength is necessary to accurately predict TC intensity. We have developed and tested automated method to estimate TC intensity based on the existing historical satellite images alone. The Hurricane Satellite data (HURSAT-B1) is used to develop the algorithm, which focuses on the North Atlantic from 1978-2009. The algorithm is trained and validated using aircraft reconnaissance-based data. Here, the data is restricted to include only fixes that are over water and are …

Go to article

Study Of N Incorporation In Insb On Gaas By Molecular Beam Epitaxy For Long Wavelength Infrared Devices, Nimai Chand Patra Jan 2013

Study Of N Incorporation In Insb On Gaas By Molecular Beam Epitaxy For Long Wavelength Infrared Devices, Nimai Chand Patra

Dissertations

The distinguishing features of dilute nitride III-V semiconductors lie in the large simultaneous reduction in the band gap and lattice parameter when N is incorporated in small amounts in an otherwise wide band gap III-V material. In particular, N incorporation in InSb is attracting great attention due to its potential applications in the long wavelength infrared (LWIR) applications. However, the relatively small atomic size of N with respect to Sb makes the growth of good quality InSbN layers challenging with effective N incorporation. In this dissertation we present a correlation of the molecular beam epitaxial growth parameters on the type …

Go to article

Application Of Nano-Imprint Lithography For Next Generation Carbon Nanotube-Based Devices, Svitlana Fialkova Jan 2013

Application Of Nano-Imprint Lithography For Next Generation Carbon Nanotube-Based Devices, Svitlana Fialkova

Dissertations

This research report addresses the development of 3D carbon nanostructures that can provide unique capabilities for manufacturing carbon nanotube (CNT) electronic components, electrochemical probes, biosensors and tissue scaffolds. The shaped CNT arrays were grown on patterned catalytic substrate by chemical vapor deposition (CVD) method. The new fabrication process for catalyst patterning based on combination of nano-imprint lithography (NIL), magnetron sputtering and reactive etching techniques was proposed and studied. The optimal process parameters for each technique were evaluated. The catalyst was made by deposition of Fe and Co nanoparticles over alumina support layer on Si/SiO2 substrate. The metal particles were …

Go to article

Architecture--Performance Interrelationship Analysis In Single/Multiple Cpu/Gpu Computing Systems: Application To Composite Process Flow Modeling, Richard Harrison Haney Jan 2013

Architecture--Performance Interrelationship Analysis In Single/Multiple Cpu/Gpu Computing Systems: Application To Composite Process Flow Modeling, Richard Harrison Haney

Dissertations

Current developments in computing have shown the advantage of using one or more Graphic Processing Units (GPU) to boost the performance of many computationally intensive applications but there are still limits to these GPU-enhanced systems. The major factors that contribute to the limitations of GPU(s) for High Performance Computing (HPC) can be categorized as hardware and software oriented in nature. Understanding how these factors affect performance is essential to develop efficient and robust applications codes that employ one or more GPU devices as powerful co-processors for HPC computational modeling. The present work analyzes and understands the intrinsic interrelationship of both …

Go to article

A Novel Approach To Intelligent Navigation Of A Mobile Robot In A Dynamic And Cluttered Indoor Environment, Daniel Opoku Jan 2013

A Novel Approach To Intelligent Navigation Of A Mobile Robot In A Dynamic And Cluttered Indoor Environment, Daniel Opoku

Dissertations

The need and rationale for improved solutions to indoor robot navigation is increasingly driven by the influx of domestic and industrial mobile robots into the market. This research has developed and implemented a novel navigation technique for a mobile robot operating in a cluttered and dynamic indoor environment. It divides the indoor navigation problem into three distinct but interrelated parts, namely, localization, mapping and path planning. The localization part has been addressed using dead-reckoning (odometry). A least squares numerical approach has been used to calibrate the odometer parameters to minimize the effect of systematic errors on the performance, and an …

Go to article