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An Invariance Transformation Algorithm For Defect Characterization Of Ultrasonic Signals For The Nondestructive Evaluation Of Concrete, Michael Dominic Ciocco

Theses and Dissertations

Nondestructive evaluation (NDE) techniques offer cost-effective strategies for monitoring the integrity of a variety of civil infrastructure, such as natural gas and sewer pipelines, without the need to take the system off-line. However, interpretation of NDE signals in terms of the location, size, and shape of underlying flaws in the material being inspected is fraught with difficulty. Typically, variations in the testing signal due to operational parameters have created a significant challenge for defect characterization. This thesis proposes, develops, and validates a defect characterization algorithm that compensates for operational variables and maps the test signal to a visual defect profile. …

Automated Segmentation Of Radiodense Tissue In Digitized Mammograms Using A Constrained Neyman-Pearson Classifier, Jeremy Thomas Neyhart

Theses and Dissertations

Breast cancer is the second leading cause of cancer related mortality among American women. Mammography screening has emerged as a reliable non-invasive technique for early detection of breast cancer. The radiographic appearance of the female breast consists of radiolucent (dark) regions and radiodense (light) regions due to connective and epithelial tissue. It has been established that the percentage of radiodense tissue in a patient's breast can be used as a marker for predicting breast cancer risk. This thesis presents the design, development and validation of a novel automated algorithm for estimating the percentage of radiodense tissue in a digitized mammogram. …

Residual Stress Effects On Fatigue Life Via The Stress Intensity Parameter, K, Jeffrey Lynn Roberts

Doctoral Dissertations

Residual stresses are known to have a significant effect on fatigue crack propagation and thus fatigue life. These effects have generally been quantified through an empirical approach, lending little help in the quantitative prediction of such effects. The weight function method has been used as a quantitative predictor, but its use neglects residual stress redistribution, treating the residual stress as a constant during crack growth. At least three different behaviors contribute to the redistribution of residual stress. First, the residual stress behind the crack tip is reduced to a negligible level as soon as the crack tip passes. Second, the …

Surface Modeling And Analysis Using Range Images: Smoothing, Registration, Integration, And Segmentation, Yiyong Sun

Doctoral Dissertations

This dissertation presents a framework for 3D reconstruction and scene analysis, using a set of range images. The motivation for developing this framework came from the needs to reconstruct the surfaces of small mechanical parts in reverse engineering tasks, build a virtual environment of indoor and outdoor scenes, and understand 3D images.

The input of the framework is a set of range images of an object or a scene captured by range scanners. The output is a triangulated surface that can be segmented into meaningful parts. A textured surface can be reconstructed if color images are provided. The framework consists …

Laser – Induced Nanostructures In Silicon, Jason Fowlkes

Doctoral Dissertations

This dissertation addresses the formation of nanostructures induced by the laser irradiation of silicon. A KrF (248 nm) pulsed excimer laser was used as the irradiation source. Irradiating micro – structured substrates in a reactive O2 atmosphere produced SiO nanostructures. Si nanoparticles were formed by irradiating both flat and micro – structured silicon surfaces in an inert gas ambient. On flat surfaces, low energy density irradiation (Ed < 1 J/cm2) induces the formation and clustering of a thin silicon film pulsed – laser deposited on silicon into nanoparticles that grow to 2 – 80 nm in diameter. Control over the Si nanoparticle diameter to within ± 1 nm could be obtained by optimizing the laser beam energy density, the inert gas pressure, and the number of laser pulses. The nanoparticles in the surface plane will self – organize into periodically spaced lines, if a periodic or quasi – periodic, microstructure is present at the surface.

A film of silicon nanoparticles was formed on the surface of a silicon target following pulsed laser irradiation in an inert, background gas. Silicon species generated during laser ablation were backscattered by the …

Intelligent Fault Tolerant Control For Telerobotic System In Operational Space, Sewoong Kim

Doctoral Dissertations

Telerobotic systems combine conventional teleoperation with industrial automation techniques, such as control, vision, planning, etc, to improve work efficiency, and have been expanding their applications from hazardous and remote areas to unstructured industrial uses. Unstructured environments and uncertainties in task space require human-in-the loop control to ensure and supervise safe operation since present autonomous capabilities cannot handle the vast range of tasks and uncertainties. The inherent characteristics of telerobotic systems make operational faults more likely, and require autonomous fault detection, isolation (FDI) and recovery abilities since the nature of task space makes it difficult for human operators to detect and …

The Effect Of Implantation Temperature And Ionizing Radiation On The Microstructure Of Ion Implanted Sapphire, Lawretta Chineze Leaticia Ononye

Doctoral Dissertations

Single crystalline specimens of aluminum oxide (Al_{2O3) were irradiated with boron, nitrogen and iron ions at room temperature and 1000^{oC to fluences of 1×1017 B+/cm2, 3×1016 N+/cm2 and 1×1017 Fe+/cm2 respectively with 150 keV of energy. Following irradiation, the structures were examined by several experimental techniques: transmission electron microscopy (TEM), Rutherford backscattering - ion channeling (RBS-C) spectroscopy, optical absorption measurements, x-ray diffraction (XRD) technique, and x-ray photoelectron spectroscopy (XPS). The samples implanted at room temperature were then annealed for one hour at 1000oC in a reducing (Ar-4%H2) gas and the microstructures examined.}}

The implantation temperature significantly influenced the …

Torque Limit Of A Mechanical Fastener In A Graphite/Epoxy Joint, Kristian M. Kostreva

Master's Theses - Daytona Beach

Presently there is a lack of confidence amongst engineers when specifying the preload of a mechanical fastener in a composite joint due to a lack of a fundamental knowledge base regarding the behavior of composites under fastener compressive load. As such, a novel experimental procedure was developed herein to determine the through-the-thickness compressive (TTTC) material properties. A total of 206 property tests were performed on four different graphite/epoxy material systems. The results confirmed that TTTC material properties vary with fiber orientation, laminate thickness, fiber volume fraction, and even laminate surface finish. Hence, the 'rule of mixtures' provides a poor estimate …

Development Of Water-Based Ink System For Braille Printing, Saurabh Varma

Masters Theses

The most commonly used system of writing by and for blind persons is called Braille, named after its French inventor, Louis Braille (1809-1952). Braille is comprised of a rectangular six-dot cell on its end, with up to 63 possible combinations using one or more of the six dots. Braille is the only reliable method of literacy for blind persons, because it enables them to read and write by touch¹.

Currently, Braille is printed by special embossers that serve as a printing press. These embossers create Braille output when it is attached appropriately to computers. The speed of these …

Investigation Of The Corrosion Of Steel By Lead-Bismuth Eutectic (Lbe) Using Scanning Electron Microscopy And X-Ray Photoelectron Spectroscopy, Daniel Koury

UNLV Theses, Dissertations, Professional Papers, and Capstones

Lead Bismuth Eutectic (LBE) has been proposed for use in programs for accelerator transmutation of waste. LBE is the leading candidate material as a spallation target and an option for the sub-critical blanket coolant. The corrosion of 316 and 316L stainless steels by LBE has been studied using UNLV's facilities for Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). We have compared exposed and unexposed samples and studied the differences. Some amount of surface contamination is present on the samples and has been removed by ionbeam etching. The unexposed samples reveal typical stainless steel characteristics: a chromium oxide passivation …

A Taxonomy Of The Adoption Of Lean Production Tools And Techniques, Bradley Mullins Greene

Doctoral Dissertations

The purpose of this study is to discover if the pattern of lean tool adoption for mature lean enterprises varies by type of value stream. The study empirically tests the effect of types of production processes, production volume, and order fulfillment strategies on lean production tool adoption in mature lean enterprises. The results of the study show that each of these factors does affect the pattern of tool adoption among mature lean enterprises.

Eleven different value stream profiles are identified in the study (ex. Discrete, Low Volume, Build-to-Order, value stream such as a commercial satellite producer). A binary logistical regression …

Metastable Phases Of Mgo-Tio2 Solid Solutions, Liang-Chieh Ma

Masters Theses

Magnesium titanium oxide powders were synthesized by the sol-gel method using alkoxides of magnesium and titanium with different ratios. Matastable phases of qandilite, Mg₂TiO₄, were found with Mg:Ti ratios down to 1.52:1 in lower temperature 600 °C than in the equilibrium condition which is above 1200 °C. Powder samples were examined by neutron powder diffraction and X-ray photoelectron spectroscopy (XPS) for analysis of structure and oxidation states. Also, samples were tested for the Mg:Ti ratios by induced coupled plasma atomic emission spectrometry. The structure refinements of the samples were done by General Structure Analysis System (GSAS) …

Adaptation Of Project Finance To Small Contractor Financing, Ragunathan Venkateswaran

Masters Theses

One key reason for the poor performance of small construction establishments in securing a higher chunk of the annual project volume is funding. While construction industry does not require a large capital investment it does require a large working capital to start up the project and generate bills so that the resulting cash flow may take over the remaining funding requirements. Unfortunately for small contractors there are very limited options available from the banks or other lending institutions to cover this large working capital requirement in the absence of sufficient collateral. The "Project Finance" method, which has been used in …

Use Of Dimples To Suppress Boundary Layer Separation On A Low Pressure Turbine Blade, Kurt P. Rouser

Theses and Dissertations

Flow separation on a low pressure turbine blade is explored at Reynolds numbers of 25k, 45k and 100k. Experimental data is collected in a low-speed, draw-down wind tunnel using a cascade of eight Pak-B blades. Flow is examined from measurements of blade surface pressures, boundary layer parameters, exit velocities, and total pressure losses across the blade. Two recessed dimple shapes are assessed for suppressing flow separation and associated losses. One dimple is spherical, and the second is asymmetric, formed from a full dimple spanwise half-filled. A single row of each dimple shape is tested at 50%, 55% and 65% axial …

Building Deconstruction Guidelines: Tools For Recovering Building Materials, Ali Ayedh Merzen

Masters Theses

The traditional method of tearing down building when its life cycle is completed is known as demolition, which means destroying most of the structures and burying it in the landfills. This is the most common practice in most countries, but in recent years there is a new movement toward using the components of these buildings. Burying usable or recyclable materials in landfills means more pollution and increasing the need for more landfills. The concept of reusing or recycling building materials is known as Deconstruction. This practice is relatively new in the construction industry and requires more research and studies to …

Using The Boundary Element Method For Prediction Of Sound Radiated From An Arbitrarily Shaped Vibrating Body, Mark J. Christensen

Masters Theses

The Boundary Element Method can be used to predict sound pressure levels radiated from an arbitrarily shaped vibrating body. Using the Direct, Indirect and Approximation formulation one can solve such an ‘exterior’ acoustic problem. In this work, the Direct formulation was chosen. The two major methods employed for implementation of this formulation are the Combined Helmholtz Integral Equation Formulation (CHIEF) and the Burton–Miller Method. Since the CHIEF method was easier to program and adapt to changes, it was decided that the CHIEF method would be the focus of this research. Using the CHIEF method as a guide, a computer simulation …

Development Of A Simulation For The Prediction Of Pvdf Surface Velocity Sensor Response For Vibrating Beams And Rectangular Plates, Brian C. Zellers

Masters Theses

A simulation for the prediction of Polyvinylidene Flouride (or PVDF) sensor charge response to structural vibration displacements of beam and rectangular plate structures was developed. The simulation uses measured vibration displacements from an actual structure using point sensors (accelerometers) assembled in an array on the surface of the structure. The PVDF sensor charge output equation was written for a PVDF film of constant spatial sensitivity so that numerical analysis tools in Matlab® can be used to solve the equation. Preliminary experimental results showed that the bending strain component, due to transverse vibration displacements, is the dominant term for both the …

An Imaging System For Concrete Bridge Inspection, Mohammed Talal Al-Bataineh

Masters Theses

Bridges are the most important element in the road network because of, the strategic position a bridge occupies, its direct impact on safety, and its high cost. Therefore, a continuous maintenance and inspection should be performed. During the past years visual inspection has been the primary method of bridge inspection.

Pontis is a comprehensive bridge management system developed as a tool to assist in the challenging task of bridge management. Pontis stores bridge inventory and inspection data and formulates network-wide preservation and improvement policies for use in evaluating the needs of each bridge in a network.

The concrete bridge inspection …

Management Commitment To Construction Safety, Areen M. Shaar

Masters Theses

The objective of all businesses including construction is to make money and to be profitable. The costs resulting from personal injuries and equipment damage, combined with the associated financial impact resulting from schedule disruptions, insurance hikes, and workers compensation can definitely impact the profitability of any construction operation. Most times those costs can be minimized or avoided by giving safety more attention on construction job sites.

The main purpose of this research is to determine the correlation between management commitment to safety and its impacts on the frequency of injuries and illnesses. To achieve this, a survey was methodically developed …

Resonance Detection And Acoustic Behaviour In Polymer Intake Manifolds, Amrith Ramanan

Masters Theses

The Automotive Industry, over the last few years, has been placing major emphasis on the use of lightweight components in engines as well as other structural components. The material for these lightweight components are being chosen in such a way that they require minimal secondary operations to place the components in service. One area that has developed is the use of Polymer (Plastic) Intake Manifolds for Internal Combustion engines. Plastics meet all the criteria for quality low cost production with a minimum weight component. Plastic intake manifolds, however, have been found to be excessively noisy in operation. This noise can …

Development Of A Data Driven Multiple Observer And Causal Graph Approach For Fault Diagnosis Of Nuclear Power Plant Sensors And Field Devices, Ke Zhao

Masters Theses

Data driven multiple observer and causal graph approach to fault detection and isolation is developed for nuclear power plant sensors and actuators. It can be integrated into the advanced instrumentation and control system for the next generation nuclear power plants.

The developed approach is based on analytical redundancy principle of fault diagnosis. Some analytical models are built to generate the residuals between measured values and expected values. Any significant residuals are used for fault detection and the residual patterns are analyzed for fault isolation.

Advanced data driven modeling methods such as Principal Component Analysis and Adaptive Network Fuzzy Inference System …

A Performance Study Of Lam And Mpich On An Smp Cluster, Brian Patrick Kearns

Dissertations and Theses

Many universities and research laboratories have developed low cost clusters, built from Commodity-Off-The-Shelf (COTS) components and running mostly free software. Research has shown that these types of systems are well-equipped to handle many problems requiring parallel processing. The primary components of clusters are hardware, networking, and system software. An important system software consideration for clusters is the choice of the message passing library.

MPI (Message Passing Interface) has arguably become the most widely used message passing library on clusters and other parallel architectures, due in part to its existence as a standard. As a standard, MPI is open for anyone …

Online Determination Of The Steady-State Condition Of An Aerodynamic Test Article Mounted In A Wind Tunnel Test Cell, Martin Vincent Fette

Masters Theses

The Propulsion Wind Tunnel (PWT) facility at Arnold Engineering Development Center is devoted to aerodynamic and propulsion integration testing of large-scale aerodynamic models. Models of aircraft, missiles and rockets are tested at simulated altitude conditions from sea level to about 150,000 feet.

Before the data acquisition sequence, it is necessary to establish that the model position has stabilized following the movement of the test model to a new orientation. The existing procedure requires an extra delay, after moving the model, before data is acquired. This delay, however, may be more or less than necessary, resulting in wasted testing time or …

Extension Of The Continuity Constraint Algorithm To Variable-Density Flow Simulation, Mark William Yambert

Masters Theses

One class of problems commonly encountered in the study of computational fluid dynamics involves the flow of fluids with variable density. Such flows are characterized by density variations too large for the assumption used in most incompressible Navier-Stokes formulations, that small changes in density are linearly proportional to changes in temperature, to be valid. Unlike fully compressible flows, such as the high-speed flow of gases, variable-density flows are often characterized by low Mach numbers. Examples of such flows include 1) combustion problems, where significant density variations may arise due to the large temperature differences present, and 2) flows involving liquids, …

Scale Model Investigations Of The Effects Of Flow Conditioning Devices, Grady P. Saunders

Masters Theses

A scale model was constructed of a portion of a supersonic wind tunnel to perform experiments on various flow conditioning devices. The various devices researched were: swirl vanes, screens, honeycombs, and various combinations thereof. Each flow conditioning device was analyzed to show its effect on total pressure profiles, static pressure profiles, test section flow angularity, test section turbulence, and acoustic noise. Of most concern are the effects flow conditioning devices have on temporal fluctuation of previously mentioned parameters.

The data from these experiments were used as the basis for selecting a screen-honeycomb combination to be installed in the full-scale tunnel. …

Evolution Of A Monomer Concentration Field In A Micro-Fluidic Channel, Michael Francis Kirsch

Masters Theses

The purpose of this research is to determine how long a micro-channel could be in the production of Non-Linear Optical Thin Film Wave-Guides. In determining this length, it is necessary to compute the monomer diffusion process between two solutions of monomers in a micro channel flow. Two models of this flow were created, the first with no flow in a one dimensional channel making diffusion a function of time and position and the second of flow in a two dimensional channel with an imposed velocity profile. Using these models it was determined that the micro channel could be the longest …

Discrete Event Simulation In Manufacturing Environments: The Waste Isolation Pilot Plant, Benjamin Thomas Burnette

Masters Theses

The purpose of this thesis was to construct a discrete event model of the waste handling activities inside of the Waste Isolation Pilot Plant (WIPP) in order to examine "what-if" scenarios designed to increase the rate at which waste is disposed.

The discrete event modeling software EXTEND was chosen by Sandia National Laboratories (Sandia) because of its ease of use, flexibility, ability to customize, and low cost. Historical and observed data were used to construct, verify, and validate the resulting model. Verification ensures that the model works as programmed, and validation ensures the real world system is truly being modeled …

Electronic Data Collection For Rockfall Hazard Evaluation, Derrick Ladon Bellamy

Masters Theses

Rockfall field data collection traditionally has used conventional stationery tools, i.e. pencil and paper, for data collection. Traditional methodologies are being revisited with the advent of PDA’s (Personal Digital Assistants) or penbased computers. With the utilization of such technology, field data can be collected electronically. An electronic data collection system using PDA’s was developed for this thesis. The advantages of the PDA approach over pencil and paper data collection include automatic error and data integrity checks during data input, and the elimination of manual data entry. The PDA’s also allow automatic branching to solicit data input based on previous data …

Investigation Of Nitrogen And Phosphorus Bearing Species In Steam Gasification Of Poultry Litter, Bratendu Bagchi

Masters Theses

The production of broiler chickens has become one of the largest sectors in United States agriculture and the growing demand for poultry has led to an annual production growth rate of five percent. Over 70 percent of the production can be traced to the Southeastern United States. With increased demand for poultry, poultry litter management has become a major challenge in the agriculture industry and for the United States Department of Agriculture.

One of the options being considered for chicken litter management is steam gasification of the litter. Detailed study and research of this option has already been carried out …

Analysis And Characterization Of Single-Poly Floating Gate Devices In 0.35um Pdsoi Process, Chandra Sekhar Acharyulu Durisety

Masters Theses

The purpose of this thesis is to demonstrate a single-poly Floating Gate Device (FGD) in 0.35 m Partially Depleted Silicon On Insulator (PDSOI) process for use in analog circuits for post process trimming. Floating gate devices with different aspect ratios have been fabricated to facilitate this behavioral study in PDSOI process. Fundamentals of floating gate devices, the advantages and disadvantages of PDSOI compared to bulk CMOS with respect to single-poly floating gate devices are discussed. Various experiments on behavior and performance of threshold voltage have been conducted and its variation with programming/erasing time and amplitude has been analyzed. The single-poly …