Engineering Commons^™

Towards A Universal Ultra-Thin Fluorinated Diamond-Like Carbon Coating For Nanoimprint Lithography Imprinters, Ryan Winfield Fillman

Theses and Dissertations

Nanoimprint lithography (NIL) has proven to achieve arbitrary, nanoscale features, over large areas, without the use of costly step-and-repeat UV lithography tools. The fidelity of the imprinted pattern depends on the elimination of the adhesion between the imprinted polymer and the imprinter upon withdrawal of the imprinter. The plasma deposition of a layer of fluorinated diamond-like carbon (F-DLC) has proven to be a successful anti-adhesion layer but in the past has required an entire diamond-like carbon (DLC) substrate. The requirement that the imprinter be made of DLC limits the imprinter processing and can limit the capabilities of NIL. DLC films …

Integration Of Multiple Data Types In 3-D Immersive Virtual Reality (Vr) Environments, George Demetrius Lecakes Jr.

Theses and Dissertations

Intelligent sensors have begun to play a key part in the monitoring and maintenance of complex infrastructures. Sensors have the capability not only to provide raw data, but also provide "information" by indicating the reliability of the measurements. The effect of this added information is a voluminous increase in the total data that is gathered. If an operator is required to perceive the state of a complex system, novel methods must be developed for sifting through enormous data sets. Virtual reality (VR) platforms are proposed as ideal candidates for performing this task-- a virtual world will allow the user to …

Diesel Particulate Matter Quantification And Reduction Strategies For School Buses, David Martinez-Morett

Theses and Dissertations

This thesis evaluated the contributions of school bus self pollution from both the crankcase and the tailpipe emissions to in-cabin levels of fine and ultrafine particulate matter, and determined the effectiveness of commercially available retrofit technologies towards reducing levels of particulate matter inside the school bus passenger compartment. Mobile tests were conducted with a school bus powered by an International DT466E engine on an outdoor test track. Measurements of fine and ultrafine particle concentrations within the cabin of a school bus were performed with and without retrofit technologies.

The tests utilized a drive cycle using data from actual school bus …

Development Of An Electroencephalography-Based Brain-Computer Interface Supporting Two-Dimensional Cursor Control, Dandan Huang

Theses and Dissertations

This study aims to explore whether human intentions to move or cease to move right and left hands can be decoded from spatiotemporal features in non-invasive electroencephalography (EEG) in order to control a discrete two-dimensional cursor movement for a potential multi-dimensional Brain-Computer interface (BCI). Five naïve subjects performed either sustaining or stopping a motor task with time locking to a predefined time window by using motor execution with physical movement or motor imagery. Spatial filtering, temporal filtering, feature selection and classification methods were explored. The performance of the proposed BCI was evaluated by both offline classification and online two-dimensional cursor …

Spatial Detection Of Multiple Movement Intentions From Sam-Filtered Single-Trial Meg For A High Performance Bci, Harsha Battapady

Theses and Dissertations

The objective of this study is to test whether human intentions to sustain or cease movements in right and left hands can be decoded reliably from spatially filtered single trial magneto-encephalographic (MEG) signals. This study was performed using motor execution and motor imagery movements to achieve a potential high performance Brain-Computer interface (BCI). Seven healthy volunteers, naïve to BCI technology, participated in this study. Signals were recorded from 275-channel MEG and synthetic aperture magnetometry (SAM) was employed as the spatial filter. The four-class classification for natural movement intentions was performed offline; Genetic Algorithm based Mahalanobis Linear Distance (GA-MLD) and direct-decision …

The Production And Filtration Efficiency Testing Of Nonwoven Electrospun Fiber Mats, Jan Uecker

Theses and Dissertations

In this thesis the production and filtration performance of electrospun nylon-4,6 nanofiber mats was experimentally studied. The average fiber diameter of nylon-4,6 fibers is controlled by altering the polymer concentration in solution. Adding small amount of pyridine to the electrospinning solution controlled fiber beading and other defects. These fibers were then deposited onto a wide variety of conductive and dielectric substrate materials. A corona ion source was used to eliminate surface charging effects observed at the surface of all substrates. The resulting fiber mats, uniform in size and distribution as verified by SEM imaging, are tested for filtration efficiency and …

Fabrication And Characterization Of Bioactive, Composite Electrospun Bone Tissue Engineering Scaffolds Intended For Cleft Palate Repair, Parthasarathy Madurantakam

Theses and Dissertations

Tissue Engineering is a scientific discipline that aims to regenerate tissues and organs that are diseased, lost or congenitally absent. It encompasses the use of suitable synthetic equivalents of native extracellular matrix that may or may not be supplemented with cells or relevant growth factors. Such scaffolds are designed to reside at the site of implantation for a variable period of time during which they induce the regeneration of native tissue. During this time, they also provide a template for new cells to attach, infiltrate, differentiate into appropriate phenotype and eventually restore function of the concerned tissue. Among the factors …

Radiation And Convection Heat Transfer In Wildland Fire Environments, David J. Frankman

Theses and Dissertations

Wildland fire research has been extensive and on going since before 1950. The motivation behind this research is to prevent loss of property and lives. In spite of this research, the heat transfer of fuel ignition and flame spread is not well understood. This dissertation seeks to fill gaps in this understanding through modeling and also by experimentation. The effect of water vapor on the transmission of thermal radiation from the flame to the fuel was investigated. The Spectral Line Weighted-sum-of-gray-gases approach was adopted for treating the spectral nature of the radiation. The study reveals that water vapor has only …

A Methodology For Designing Product Components With Built-In Barriers To Reverse Engineering, Stephen P. Harston

Theses and Dissertations

Reverse engineering, defined as extracting information about a product from the product itself, is a common industry practice for gaining insight into innovative products. Both the original designer and those reverse engineering the original design can benefit from estimating the time and barrier to reverse engineer a product. This thesis presents a set of metrics and parameters that can be used to calculate the barrier to reverse engineer any product as well as the time required to do so. To the original designer, these numerical representations of the barrier and time can be used to strategically identify and improve product …

A Method For Making In Situ Emittance Measurements Of Coal Ash Deposits, Travis J. Moore

Theses and Dissertations

A major problem associated with any power generation process in which coal is burned is the formation of ash and slag from the inorganic constituents of the coal. Ash deposition on heat transfer surfaces in coal-fired reactors is unavoidable and can have a significant effect on the performance and maintenance of boilers and gasifiers. A greater understanding of the thermal properties of coal ash deposits is important in reducing their negative impact. This work presents the development of an experimental method for making in situ measurements of the spectral emittance of coal ash deposits. It also provides measured emittances for …

Visualizing And Modeling Mining-Induced Surface Subsidence, Marcor Gibbons Platt

Theses and Dissertations

Ground subsidence due to underground coal mining is a complex, narrowly-understood phenomenon. Due to the complicated physical processes involved and the lack of a complete knowledge of the characteristics of overlying strata, the reliability of current prediction techniques varies widely. Furthermore, the accuracy of any given prediction technique is largely dependent upon the accuracy of field measurements and surveys which provide input data for the technique. A valuable resource available for predicting and modeling subsidence is aerial survey technology. This technology produces yearly datasets with a high density of survey points. The following study introduces a method wherein these survey …

Characterizing Material Property Tradeoffs Of Polycrystalline Diamond For Design Evaluation And Selection, Neil David Haddock

Theses and Dissertations

Polycrystalline diamond (PCD) is used as a cutting tool in many industries because of its superior wear resistance compared to single crystal diamond. Engineers who design new PCD materials must have an understanding of the tradeoffs between material properties in order to tailor a product for different applications. Two competing material properties that are often encountered in PCD are transverse rupture strength and thermal-resistance. Thermal-resistance is directly related to the cobalt content of PCD, and is the ability of the material to withstand thermally induced degradation. In this thesis, we characterize the tradeoff boundary between transverse rupture strength and cobalt …

Construction Of Large Geo-Referenced Mosaics From Mav Video And Telemetry Data, Benjamin Kurt Heiner

Theses and Dissertations

Miniature Aerial Vehicles (MAVs) are quickly gaining acceptance as a platform for performing remote sensing or surveillance of remote areas. However, because MAVs are typically flown close to the ground (1000 feet or less in altitude), their field of view for any one image is relatively small. In addition, the context of the video (where and at what orientation are the objects being observed, the relationship between images) is unclear from any one image. To overcome these problems, we propose a geo-referenced mosaicing method that creates a mosaic from the captured images and geo-references the mosaic using information from the …

An Investigation Of Middle School Student Interest, Perception, And Attitude Toward Technology And Engineering, Kari Marie Cook

Theses and Dissertations

The purpose of this study was to investigate middle school student perception and attitude toward technology and engineering and to better understand how the gender of the teacher, gender of the student, and information provided in technology classes affected their perception and attitude. To accomplish this, the Technology Attitude Scale, and the Pupil's Attitudes Toward Technology—United States assessment instruments were used to form the basis of a new survey instrument focused on technology and engineering perception, use, and interest. The new survey instrument is called the Technology and Engineering Attitude Scale (TEAS) survey. Multiple 7th grade technology engineering classes from …

Offset Qpsk In Siso And Mimo Environments, Xiaoyu Dang

Theses and Dissertations

We demonstrate how the performance of offset quadrature phase-shift keying (OQPSK) and its variants of Feher-patented QPSK (FQPSK) and Shaped Offset QPSK (SOQPSK) (collectively known as the ARTM Tier-1 waveforms) in single input single output (SISO) system could change with the channel fading parameters. The bit error rate expression of offset QSPK and ATRM Tier-1 waveforms over the aeronautical telemetry multipath channel has been derived. Simulations show that for the case of a single multipath ray, the BER gets worse with increasing Γ for a fixed delay, and that the BER has a quasi-periodic property for fixed Γ and increasing …

Obstacle Avoidance, Visual Automatic Target Tracking, And Task Allocation For Small Unmanned Air Vehicles, Jeffery Brian Saunders

Theses and Dissertations

Recent developments in autopilot technology have increased the potential use of micro air vehicles (MAVs). As the number of applications increase, the demand on MAVs to operate autonomously in any scenario increases. Currently, MAVs cannot reliably fly in cluttered environments because of the difficulty to detect and avoid obstacles. The main contribution of this research is to offer obstacle detection and avoidance strategies using laser rangers and cameras coupled with computer vision processing. In addition, we explore methods of visual target tracking and task allocation. Utilizing a laser ranger, we develop a dynamic geometric guidance strategy to generate paths around …

Radio Frequency Interference Mitigation On The Very Small Array, Alan Joseph Stemmons

Theses and Dissertations

Radio astronomical synthesis imaging arrays can create images with resolution much higher than can single dish telescopes. However, one of the biggest problems that imaging arrays face is radio frequency interference (RFI). This interference corrupts signals and prevents accurate image creation. Therefore, it is necessary to remove this interference. This thesis discusses the synthesis imaging procedure and array spatial filter­ing methods to remove interference, including Multiple Sidelobe Canceller (MSC), Subspace Projection (SP), and Cross­-Subspace Projection (CSP). The CLEAN algorithm, an image restoration technique, is also discussed. Various improvements to the VSA are discussed, including upgrades to the hardware and software …

Development Of Methods To Propagate Energy Density And Predict Farfield Directivity Using Nearfield Acoustic Holography, Scott Richard Woolston

Theses and Dissertations

Acoustical-based imaging systems have found merit in determining the behavior of vibrating structures. This thesis focuses on the continued development of the nearfield acoustic holography (NAH) approach. Conventional NAH consists of first measuring the pressure field on a two-dimensional conformal surface and then propagating this data back to the vibrating structure to obtain information about the source, such as the normal velocity distribution. Recent work has been done which incorporates particle velocity information into the traditional NAH measurements to reduce the number of measurements required. This advancement has made NAH a more affordable tool for acoustical imaging and sound field …

Design And Analysis Of A Dual-Mode Cascaded-Loop Frequency Synthesizer, Xiongliang Lai

Theses and Dissertations

A new architecture for a frequency synthesizer with adjustable output frequency range and channel spacing is introduced. It is intended for the generation of closely spaced frequency channels in the GHz range while producing minimal spurious phase noise components. The architecture employs two independent phase-locked loops that are driven in cascade by a single reference oscillator. The approach provides fine resolution and wide bandwidth as well as low phase noise and should find application in many contemporary communication systems. The synthesizer can be operated in either of two different modes: nonfractional and mini-denominator fractional modes. The architecture produces no fractional …

An Investigation Of Utah Technology Education Teachers' Acceptance Of An Emphasis On Engineering Education Content, Douglas Ron Livingston

Theses and Dissertations

The purpose of this study is to collect information documenting Utah technology education teachers' acceptance of an emphasis on engineering content in technology education. The Stages of Concern Questionnaire (SoCQ) was used to determine the level of acceptance of this change. It was found that a majority of technology and education teachers are more concerned about other unidentified tasks, activities or initiatives than they are about the addition of engineering content to their classes. They were also shown to be concerned with being able to organize, manage, and schedule the change effectively and were found to be least concerned about …

Computational Modeling Of The Helical Axis In The Human Knee--Detecting Changes In The Transverse Plane, Emily Carney

Theses and Dissertations

The purpose of this study was to build a helical axis algorithm capable of detecting changes in the helical axis intersection of the tibia and femur in human knees. This algorithm was designed and tested using three models: a multiplanar rigid body model, a mathematical model, and a cylinder model. The multiplanar rigid body model closely mimics knee movement without supporting ligamentous structures, thus the movement was unconstrained. In this model kinematic position data were collected using both MotionMonitor™ (MotionMonitor™ Version 7.7, Innovative Sports Training, Chicago, IL) and Vicon Nexus 1.3 software system (Oxford Metrics Group, Oxford, UK). To test …

Optimized Distribution Of Strength In Buckling-Restrained Brace Frames In Tall Buildings, Graham Thomas Oxborrow

Theses and Dissertations

Nonlinear time history analysis is increasingly being used in the design of tall steel structures, but member sizes still must be determined by a designer before an analysis can be performed. Often the distribution of story strength is still based on an assumed first mode response as determined from the Equivalent Lateral Force (ELF) procedure. For tall buckling restrained braced frames (BRBFs), two questions remain unanswered: what brace distribution will minimize total brace area, while satisfying story drift and ductility limits, and is the ELF procedure an effective approximation of that distribution? In order to investigate these issues, an optimization …

Cross-Correlation-Based Texture Analysis Using Kinematically Simulated Ebsd Patterns, Joshua Peter Kacher

Theses and Dissertations

The development and example applications of a new EBSD-based texture analysis system are presented. This new system uses the cross-correlation function to compare two EBSD patterns at a number of corresponding regions in each pattern to calculate the deformation gradient tensor. Bragg's Law-based simulated EBSD patterns are used as reference patterns in the cross-correlation method to enable the measurements of absolute elastic strain and lattice orientation at discrete points in a crystalline sample. The resolution limits of this new method are explored using a variety of computational and physical experiments. The simulated pattern method is estimated to be able to …

Controlled Synthesis Of Zno Nanowires Towards The Fabrication Of Solar Cells, Dongshan Yu

Theses and Dissertations

In recent years, quasi-one-dimensional materials have attracted a lot of research attention due to their remarkable properties, and their potential as building blocks for nanoscale electronic and optoelectronic devices. A modified chemical vapor deposition (CVD) method has been used to synthesize ZnO nanowires. Electron microscopy and other characterization techniques show that nanowires having distinct morphologies when grown under different conditions. The effects of reaction parameters including reaction time, temperature, carrier gas flow rate, substrates and catalyst material upon the size, shape, and density of ZnO nanowire arrays have been investigated. Excitonic solar cells —including Gratzel-type cells, organic and hybrid organic/inorganic …

Tissue Engineering Cellularized Silk-Based Ligament Analogues, Scott Sell

Theses and Dissertations

The resurgence, and eventual rise to prominence in the field of tissue engineering, that electrospinning has experienced over the last decade speaks to the simplicity and adaptability of the process. Electrospinning has been used for the fabrication of tissue engineering scaffolds intended for use in nearly every part of the human body: blood vessel, cartilage, bone, skin, nerve, connective tissue, etc. Diverse as the aforementioned tissues are in both form and function, electrospinning has found a niche in the repair of each due to its capacity to consistently create non-woven structures of fibers ranging from nano-to-micron size in diameter. These …

Comparison Of Passive Cervical Spine Flexion In Children And Adults, Jami Saffioti

Theses and Dissertations

Head trauma is the most frequent injury sustained by children in car crashes, and the neck plays a key role in governing head kinematics during the crash. Pediatric anthropomorphic test devices (ATDs) are used to assess the risk of head injury, yet the pediatric ATD neck is a size-scaled model of the adult ATD neck, with no consideration for the tissue properties and morphological changes during human development. To help understand the effects of maturation on the changes in neck flexion biomechanics, this study compared the passive cervical spine flexion of children to adults in specific age groups (6-8, 9-12, …

Applications Of Variation Analysis Methods To Automotive Mechanisms, Robert C. Leishman

Theses and Dissertations

Variation analysis, or tolerance analysis as it is sometimes called, is typically used to predict variation in critical dimensions in assemblies by calculating the stack-up of the contributing component variations. It is routinely used in manufacturing and assembly environments with great success. Design engineers are able to account for the small changes in dimensions that naturally occur in manufacturing processes, in equipment, and due to operators and still ensure that the assemblies will meet the design specifications and required assembly performance parameters. Furthermore, geometric variation not only affects critical fits and clearances in static assemblies, it can also cause variation …

Evaluation Of The Benefits Of Oxy-Combustion On Emissions From A Compression Ignition Engine, Thomas A. Salt

Theses and Dissertations

In this research the benefits of applying oxy-combustion in a diesel engine to reduce NOx and particulate emissions were evaluated. The addition of oxygen to the intake in conjunction with exhaust gas recirculation (EGR) was shown to reduce NOx without an increase in particulate. Indicated specific NOx and particulate emissions for oxygen-enhanced EGR (O-EGR) and EGR without oxygen addition (normal or N-EGR) were compared at three engine loads. NOx emissions correlated with flame temperature for both N-EGR and O-EGR but were slightly lower at a given flame temperature for O-EGR. Flame temperature reduction for N-EGR was primarily through dilution of …

Effects Of Prior Aging At 288°C In Argon Environment On Creep Response Of Carbon Fiber Reinforced Pmr-15 Composite With ±45°Fiber Orientation At 288°C, Tyler F. Gruters

Theses and Dissertations

The creep and recovery response of carbon fiber reinforced PMR-15 composite with a + or - 45 fiber orientation was examined in an argon environment at 288 deg C. Mechanical testing was executed for unaged specimens as well as specimens aged up to 1000 hours. Tensile tests were performed to determine Young's modulus of elasticity and ultimate tensile strength. The creep tests were carried out at stress levels of 30 and 60 MPa. Creep periods of 25 hours were followed by recovery periods of 50 hours at zero stress. Weight loss measurements as a function of aging time were taken …

Slip Lined Culvert Retrofit And Fish Passage, Joseph Ray Webb

Theses and Dissertations

Culverts throughout the country are approaching or are past their original design lives. These ‘baby boomer’ culverts will need to be repaired, rehabilitated, or replaced. Because entire culvert replacement is so expensive and intrusive, alternate measures to extend the culvert project life are growing increasingly popular. One such method is slip lining, where a ‘sleeve’ is installed within an existing culvert barrel and stabilized. Plastic pipe sleeves are very popular for slip lining primarily because the plastic material's lower Manning's roughness values allow for the culvert capacity to be maintained despite a reduction in culvert size. Unfortunately, the reduced friction …