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Retrospective Theses and Dissertations

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Full-Text Articles in Engineering

Establishing An Advanced Engineering Framework For Engineering Decision Making, Douglas Stinson Mccorkle Jan 2008

Establishing An Advanced Engineering Framework For Engineering Decision Making, Douglas Stinson Mccorkle

Retrospective Theses and Dissertations

No abstract provided.


Protein Extraction From Distiller's Grain, Drew John Cookman Jan 2008

Protein Extraction From Distiller's Grain, Drew John Cookman

Retrospective Theses and Dissertations

The drastic increase in ethanol production over the last 10 years has led to overproduction of distiller's grain (DG), an ethanol byproduct. In this study, we investigated the feasibility of extracting the protein from unmilled and milled DG leaving a carbohydrate-rich solid phase that could be used for the production of more ethanol. Protein extractions based on aqueous ethanol (both with and without a pretreatment of a reducing agent), alkaline-ethanol, and aqueous enzyme treatments were compared.;Three methods led to a significant amount of protein being extracted from DG. An enzymatic extraction decreased the crude protein content in the ...


Monitoring Vegetative Treatment System Performance For Open Beef Feedlot Runoff Control, Ishadeep Khanijo Jan 2008

Monitoring Vegetative Treatment System Performance For Open Beef Feedlot Runoff Control, Ishadeep Khanijo

Retrospective Theses and Dissertations

Vegetative treatment systems (VTS) are an alterative technology designed to control runoff from open beef feedlots. A VTS consists of a solids settling basin (SSB) followed by a vegetative treatment area (VTA) or a combination of vegetative infiltration basin (VIB) and a VTA. Four sites were monitored in 2006 and 2007 to evaluate the performance of the VTSs in Iowa. In 2006, the percent runoff control at Central IA 1 & 2 and Northwest IA 1 & 2 was measured as 99, 74, 96, and 98 respectively. In 2007, the SSB outlets were actively managed and the percent runoff control at Central ...


Characterization Of Actuator Behaviors Of Ferrogels Obtained From Physical And Chemical Cross-Linking Methods, Geunhyung Park Jan 2008

Characterization Of Actuator Behaviors Of Ferrogels Obtained From Physical And Chemical Cross-Linking Methods, Geunhyung Park

Retrospective Theses and Dissertations

Ferrogels are soft polymer materials containing a filler of magnetic particles that allow the material to be activated by magnetic fields. These materials have shown capabilities for large strains, fast response, ease of synthesis and biocompatibility and have potential applications including artificial muscles, controlled drug release systems, and hyperthermia cancer treatment. In this work, the actuator behavior for a selection of ferrogel compositions and synthesis methods are characterized including their free strain and loading behavior. Samples were synthesized using either chemical or physical methods using Sodium Tetra-borate (Na2B4O7 ยท 10(H2O)) or freeze-thaw cycle, respectively. Compositions consisting of PVA of 4 ...


Characterization Of Conductive Surface Printing Via Electric Field Induced Ion Transport, Khiam-How Low Jan 2008

Characterization Of Conductive Surface Printing Via Electric Field Induced Ion Transport, Khiam-How Low

Retrospective Theses and Dissertations

A novel methodology to imprint micron size features on copper surface has been adopted in this study. The process of printing is based on focused electric field induced ion transport across a cation selective NafionRTM membrane. The imprinting technology itself is environmentally benign because electrolyte consists of Sulfuric Acid (H2SO4) and Cupric Sulfate (CuSO4) are encapsulated by NafionRTM membrane in a copper made cathode chamber and it is sealed and recycled. In addition, the imprinted surface does not come in contact with corrosive chemicals which minimize the post cleaning process.;Three different methods of printing were embraced here in this ...


Design And Field Testing Of Tapered H-Shaped Ultra High Performance Concrete Piles, Thomas L. Vande Voort Jan 2008

Design And Field Testing Of Tapered H-Shaped Ultra High Performance Concrete Piles, Thomas L. Vande Voort

Retrospective Theses and Dissertations

The strategic plan for bridge engineering issued by AASHTO in 2005 identified material deterioration as one of the primary challenges to achieving extended life. In substructural applications, construction materials such as steel and concrete are subjected to deterioration. Ultra High Performance Concrete (UHPC) has a compressive strength of 26,000 psi (180 MPa) and excellent durability, and this study explores the possibility of using precast, prestressed UHPC piles. An H-shaped UHPC section, which is 10-in. (250-mm) deep, was designed for constructability and economical reasons. Instrumented UHPC elements were cast to conduct large-scale field tests. In the field, two UHPC piles ...


Advancing Block-Oriented Modeling In Process Control, Stephanie Diane Loveland Jan 2008

Advancing Block-Oriented Modeling In Process Control, Stephanie Diane Loveland

Retrospective Theses and Dissertations

The increasing pressure in industry to maintain tight control over processes has led to the development of many advanced control algorithms. Many of these algorithms are model-based control schemes, which require an accurate predictive model of the process to achieve good controller performance. Because of this, research in the fields of nonlinear process modeling and predictive control has advanced over the past several decades.;In this dissertation, a new method for identifying complicated block-oriented nonlinear models of processes will be proposed. This method is applied for LNL and LLN "sandwich" block-oriented models and will be shown to accurately predict process ...


A New Approach Of Top-Down Induction Of Decision Trees For Knowledge Discovery, Jun-Youl Lee Jan 2008

A New Approach Of Top-Down Induction Of Decision Trees For Knowledge Discovery, Jun-Youl Lee

Retrospective Theses and Dissertations

Top-down induction of decision trees is the most popular technique for classification in the field of data mining and knowledge discovery. Quinlan developed the basic induction algorithm of decision trees, ID3 (1984), and extended to C4.5 (1993). There is a lot of research work for dealing with a single attribute decision-making node (so-called the first-order decision) of decision trees. Murphy and Pazzani (1991) addressed about multiple-attribute conditions at decision-making nodes. They show that higher order decision-making generates smaller decision trees and better accuracy. However, there always exist NP-complete combinations of multiple-attribute decision-makings.;We develop a new algorithm of second-order ...


Visualizing Fluidized Beds With X-Rays, Nathan Paul Franka Jan 2008

Visualizing Fluidized Beds With X-Rays, Nathan Paul Franka

Retrospective Theses and Dissertations

This study applies minimum fluidization velocity experiments, X-ray computed tomography (CT), X-ray stereography, and particle tracking to fluidized beds of glass beads, ground walnut shell, and ground corncob operating with a variety of flow conditions. 3-D local, time-averaged gas holdup is calculated from CT data, while dynamic features are captured by X-ray stereography. The results show that CT is most effective on glass bead fluidized beds. Due to high X-ray attenuation, glass bead CT data has higher resolution than walnut shell and corncob beds. Glass bead gas holdup data also feature the lowest noise due to the high homogeneity of ...


Measurement Of Minority Carrier Lifetimes In Nanocrystalline Silicon Devices Using Reverse-Recovery Transient Method, Philip David Reusswig Jan 2008

Measurement Of Minority Carrier Lifetimes In Nanocrystalline Silicon Devices Using Reverse-Recovery Transient Method, Philip David Reusswig

Retrospective Theses and Dissertations

A new technique for measuring minority carrier lifetimes in p-i-n device configurations, and is used to measure the effective hole lifetimes in nanocrystalline silicon materials. The technique is the reverse-recovery transient method. A forward current in a p-n junction is suddenly switched, and a high constant reverse current flows for a certain period of time. This time is related to the time the injected minority carriers take to recombine in the base. The technique allows for analysis of hole lifetimes in typical thin film nanocrystalline silicon device with very common testing equipment.;The samples used for testing were fabricated using ...


Nonlinear Device Characterization And Second Harmonic Impedance Tuning To Achieve Peak Performance For A Sic Power Mesfet Device At 2ghz, Saalini Valli Sekar Jan 2008

Nonlinear Device Characterization And Second Harmonic Impedance Tuning To Achieve Peak Performance For A Sic Power Mesfet Device At 2ghz, Saalini Valli Sekar

Retrospective Theses and Dissertations

This thesis presents a way to make nonlinear device measurements for a power MESFET device using the load pull system. The device was characterized at the fundamental and second harmonic frequencies during large signal operation. The data thus collected was used in designing the input and output impedance matching networks that would optimize the performance of the device. A power MESFET device like the one used to conduct this experiment is mainly used in designing power amplifiers for communication systems including the transmitters used in satellites. Therefore efficiency of the part is of the utmost importance. By characterizing the device ...


Novel Composites For Microwave Absorption, Nathan Lee Fischer Jan 2008

Novel Composites For Microwave Absorption, Nathan Lee Fischer

Retrospective Theses and Dissertations

There are many instances where it is desirable to absorb specific frequencies of microwave radiation. Areas of interest include radar applications, enhancing the performance of cell phones, and in microwave-assisted curing of thermosets. An alternative to the current use of ferromagnetic particles dispersed in a matrix is to take advantage of dielectric relaxation due to interfacial polarization as the means of electromagnetic absorption.;Three composite materials composed of polydisperse electroless, polydisperse sputtered, or monodisperse electroless nickel-coated particles are examined for their electromagnetic properties in the microwave range. Complex permittivity and permeability as a function of frequency and volume fraction are ...


Potential Use Of Quasicrystalline Materials As Thermal Barrier Coatings For Diesel Engine Components, M. Brad Beardsley Jan 2008

Potential Use Of Quasicrystalline Materials As Thermal Barrier Coatings For Diesel Engine Components, M. Brad Beardsley

Retrospective Theses and Dissertations

No abstract provided.


Ethnic-Identity Intensity As A Moderator Of The Technology Acceptance Model And Its Antecedents, Marcus Anthony Alexander Jan 2008

Ethnic-Identity Intensity As A Moderator Of The Technology Acceptance Model And Its Antecedents, Marcus Anthony Alexander

Retrospective Theses and Dissertations

The goal of this dissertation is oriented to study the motivation of minorities to adopt and learn new, innovative technologies. The primary research question: is there some reason the African-American experience is driving certain sub-groups of the population to the wrong side of the digital divide? To examine this, I introduce ethnic identity as a moderating variable to a leftward extended technology acceptance model (TAM). Additionally, both components of the classic TAM (ease of use and usefulness) are divided into two antecedents: (1) ease of use - (a) trait efficacy and (b) state efficacy and (2) usefulness (completely replaced by) - (a ...


Computational Studies On The Effect Of Water Impact On An Unmanned Air Vehicle, Gregory Zink Jan 2008

Computational Studies On The Effect Of Water Impact On An Unmanned Air Vehicle, Gregory Zink

Retrospective Theses and Dissertations

Computational Fluid Dynamics (CFD) was used in conjunction with Finite Element Analysis (FEA) to simulate the water splashdown and effects thereof on an Unmanned Air Vehicle (UAV). The CFD simulation utilized time-accurate finite-volume code to model both "compressible" and "incompressible" ensemble averaged Navier-Stokes equations. The model also incorporated the volume of fluid method to track the air-water interface, and dynamic cell remeshing to move the UAV body through the computational domain. The model was verified by comparing pressure histories with experimental test data. There was good agreement in character and magnitude of these results, with some deviance in the inlet ...


Evolution, Interaction, And Intrinsic Properties Of Dislocations In Intermetallics: Anisotropic 3d Dislocation Dynamics Approach, Qian Chen Jan 2008

Evolution, Interaction, And Intrinsic Properties Of Dislocations In Intermetallics: Anisotropic 3d Dislocation Dynamics Approach, Qian Chen

Retrospective Theses and Dissertations

The generation, motion, and interaction of dislocations play key roles during the plastic deformation process of crystalline solids. 3D Dislocation Dynamics has been employed as a mesoscale simulation algorithm to investigate the collective and cooperative behavior of dislocations. Most current research on 3D Dislocation Dynamics is based on the solutions available in the framework of classical isotropic elasticity. However, due to some degree of elastic anisotropy in almost all crystalline solids, it is very necessary to extend 3D Dislocation Dynamics into anisotropic elasticity. In this study, first, the details of efficient and accurate incorporation of the fully anisotropic elasticity into ...


Carbon Conversion During Bubbling Fluidized Bed Gasification Of Biomass, Kevin Jay Timmer Jan 2008

Carbon Conversion During Bubbling Fluidized Bed Gasification Of Biomass, Kevin Jay Timmer

Retrospective Theses and Dissertations

Gasification is one means of transforming biomass so that it can be more easily utilized as a renewable source of thermal energy, transportation fuel, and chemicals. Under typical gasification conditions it is not uncommon that a portion of the carbon entering with the biomass leaves the reactor unconverted as char. Understanding and improving carbon conversion during biomass gasification in an atmospheric bubbling fluidized bed reactor is the focus of this study.;To better understand the intricacies of biomass gasification a carbon conversion analytic methodology was developed. The methodology is based on a mass balance of the fixed carbon entering and ...


Skip Entry Trajectory Planning And Guidance, Christopher William Brunner Jan 2008

Skip Entry Trajectory Planning And Guidance, Christopher William Brunner

Retrospective Theses and Dissertations

A numerical predictor-corrector (NPC) method for trajectory planning and closed-loop guidance of low lift-to-drag (L/D) ratio vehicles during the skip entry phase of a lunar-return mission is presented. The strategy calls for controlling the trajectory by modulation of the magnitude of the vehicle's bank angle. The magnitude of the bank angle used in the skip phase is determined by satisfying the downrange requirement to the landing site. The problem is formulated as a nonlinear univariate root-finding problem. Full three degree of freedom (3DOF) nonlinear trajectory dynamics are included to achieve high accuracy of the landing prediction. In addition ...


Modeling And Direct Numerical Simulation Of Particle-Laden Turbulent Flows, Ying Xu Jan 2008

Modeling And Direct Numerical Simulation Of Particle-Laden Turbulent Flows, Ying Xu

Retrospective Theses and Dissertations

The objective of this study is to improve Eulerian-Eulerian models of particle-laden turbulent flow, especially the interphase TKE transfer term and the dissipation rate in Eulerian-Eulerian models. We begin by understanding the behavior of two existing models---one proposed by Simonin (1996b), and the other by Ahmadi (1989)---in the limiting case of statistically homogeneous particle-laden turbulent flow. The decay of particle-phase and fluid-phase turbulent kinetic energy (TKE) is compared with point-particle direct numerical simulation data. Even this simple flow poses a significant challenge to current models, which have difficulty in reproducing important physical phenomena such as the variation of turbulent ...


An Innovative New Pouring Design For Steel Castings, Justin Daniel Walker Jan 2008

An Innovative New Pouring Design For Steel Castings, Justin Daniel Walker

Retrospective Theses and Dissertations

Current methods for handling and pouring molten steel into molds are problematic. Bottom pour ladles have a large pour height that translates into high pouring velocities and increased inclusions. Teapot ladles are limited in capacity and are difficult for the operator to manipulate. Both of these systems rely on manual control to deliver the metal to the sprue. This paper presents a new system that includes a redesigned ladle that has a larger capacity than teapot ladles. The movement of the ladle is computer controlled so that it will deliver metal to defined sprue location based on a prescribed flow ...


Mechanics Of Wire Saw Machining Process: Experimental Analyses And Modeling, Egemen Teomete Jan 2008

Mechanics Of Wire Saw Machining Process: Experimental Analyses And Modeling, Egemen Teomete

Retrospective Theses and Dissertations

Wire saw process is widely used to slice many ceramic crystals that are utilized in a wide range of engineering applications ranging from silicon wafers in microelectronics and photovoltaic industries to piezo-crystals for actuators and sonar detectors. The process has a higher yield, lower kerf loss and lower surface damage with respect to inner diameter saw. The wire saw process allows higher diameter and thinner wafer cutting. The process is also used in cutting almost all brittle materials including; ultra-hard carbides, high density or foam ceramics, glasses, sapphire and rocks. Wire saw process represents 30% of the total silicon wafer ...


Analyzing Impacts On Backorders And Ending Inventory In Mrp Due To Changes In Lead-Time, Demand Variability And Safety Stock Levels, James Duane Abbey Jan 2008

Analyzing Impacts On Backorders And Ending Inventory In Mrp Due To Changes In Lead-Time, Demand Variability And Safety Stock Levels, James Duane Abbey

Retrospective Theses and Dissertations

Global sourcing represents one of the major focuses in many industries as a means to lower costs. While global sourcing generally reduces per unit costs, the impact of global sourcing on total costs throughout the supply chain often remains unrecognized. Increased lead-time due to global sourcing represents one of the commonly unrecognized costs. Hence, the simulation model developed in this study demonstrates the impact of lead-time length and variation as well as variation in demand and safety stocks on the ending inventory and backorder levels in a two product MRP system. The results show that backorders grow at a diminishing ...


Computational Simulation Of Separated Flow In A Three-Dimensional Diffuser Using V2-F And Zeta-F Models, Jason Allen Ryon Jan 2008

Computational Simulation Of Separated Flow In A Three-Dimensional Diffuser Using V2-F And Zeta-F Models, Jason Allen Ryon

Retrospective Theses and Dissertations

Computational prediction of separated flows is an area of interest, specifically in applications to gas turbine engines, liquid pumps, and many other engineering applications. Although these types of flows are governed by the Navier-Stokes equations, direct numerical simulation (DNS) of practical engineering flows is currently too expensive in terms of the required computational time. It is therefore a case to attempt simulation of these flows using the Reynolds-Averaged Navier-Stokes (RANS) equations which must be closed by utilizing a turbulence closure model.;The present study used the NASA Glenn-HT code, a compressible Navier-Stokes solver, with two different turbulence models, the u2 ...


A Framework For Tumor Segmentation And Interactive Immersive Visualization Of Medical Image Data For Surgical Planning, Jung Leng Foo Jan 2008

A Framework For Tumor Segmentation And Interactive Immersive Visualization Of Medical Image Data For Surgical Planning, Jung Leng Foo

Retrospective Theses and Dissertations

This dissertation presents the framework for analyzing and visualizing digital medical images. Two new segmentation methods have been developed: a probability based segmentation algorithm, and a segmentation algorithm that uses a fuzzy rule based system to generate "similarity" values for segmentation. A visualization software application has also been developed to effectively view and manipulate digital medical images on a desktop computer as well as in an immersive environment.;For the probabilistic segmentation algorithm, image data are first enhanced by manually setting the appropriate window center and width, and if needed a sharpening or noise removal filter is applied. To initialize ...


Development Of A Multiblock Solver Utilizing The Lattice Boltzmann And Traditional Finite Difference Methods For Fluid Flow Problems, Aditya C. Velivelli Jan 2008

Development Of A Multiblock Solver Utilizing The Lattice Boltzmann And Traditional Finite Difference Methods For Fluid Flow Problems, Aditya C. Velivelli

Retrospective Theses and Dissertations

This dissertation develops the lattice Boltzmann method (LBM) as a strong alternative to traditional numerical methods for solving incompressible fluid flow problems. The LBM outperforms traditional methods on a standalone basis for certain problem cases while for other cases it can be coupled with the traditional methods using domain decomposition. This brings about a composite numerical scheme which associates the efficient numerical attributes of each individual method in the composite scheme with a particular region in the flow domain. Coupled lattice Boltzmann-traditional finite difference procedures are developed and evaluated for CPU time reduction and accuracy of standard test cases. The ...


Force Interaction Characterization Between Thrombin And Dna Aptamers, Janice Dionne Marquardt Jan 2008

Force Interaction Characterization Between Thrombin And Dna Aptamers, Janice Dionne Marquardt

Retrospective Theses and Dissertations

The first purpose of this study is to examine using AFM height measurements to detect changes in nucleic acid and protein interactions. This study used a thiolated adenine oligonucleotide (Poly A) and thymine DNA strand (Poly T) or 2 kDa poly(ethylene) glycol (PEG) as control, and the thrombin aptamer and thrombin for detection pair. The poly A and aptamer were printed using microcontact printing, then exposed to complementary species. There was a height change after binding to the target species, so it is feasible for height data to detect binding. The second purpose of this study is to use ...


Effects Of Substrate And Co-Culture On Neural Progenitor Cell Differentiation, Erin Boote Jones Jan 2008

Effects Of Substrate And Co-Culture On Neural Progenitor Cell Differentiation, Erin Boote Jones

Retrospective Theses and Dissertations

For stem and progenitor cells to become clinically useful, the factors that influence their differentiation must be better understood. The interaction between progenitor cells and their environment is thought to be one of the main influences on differentiation. This thesis examines the effects of media conditioned by primary astrocytes and extracellular matrix protein surface coatings on the differentiation of neural progenitor cells.


Experimental Investigation Of Biomimetic Wing Configurations For Micro Air Vehicle Applications, Jeffery T. Murphy Jan 2008

Experimental Investigation Of Biomimetic Wing Configurations For Micro Air Vehicle Applications, Jeffery T. Murphy

Retrospective Theses and Dissertations

The purpose of this study was to verify, explore, and better understand low Reynolds number flows associated with wing configurations/designs for potential Micro Air Vehicle (MAV) applications. Chapter 2 discusses and details the results from an experimental study entailing force measurements and Particle Image Velocimetry (PIV) of an airfoil design inspired from the wing of a dragonfly. The comparison airfoils for this experiment are a flat plate, and the 'envelope' shape formed by the streamlines of the flow passing over the corrugated airfoil. In order to achieve this streamline shape as a boundary, the corrugated airfoil was tightly wrapped ...


Development And Modeling Of A Slope Insensitive Combine Cleaning Shoe, James Monroe Hershbarger Jan 2008

Development And Modeling Of A Slope Insensitive Combine Cleaning Shoe, James Monroe Hershbarger

Retrospective Theses and Dissertations

An experimental cleaning shoe was developed to compensate for sloped land by adjustment of shake speed, fan speed, and shake geometry. Grain loss on the cleaning shoe decreased compared to a conventional cleaning shoe exposed to similar conditions. Average grain losses of 0.710% and 6.560% on 5- and 10-degree side slopes in corn were reduced to 0.118% and 0.256% on the same side slopes using only modified shake geometry. Similar reductions in grain loss were seen in wheat, from 7.521% and 15.272% on both side slopes to 3.941% and 4.722% using only ...


A Computational Study Of Quasi-2d Flows At Low Reynolds Numbers, Haiyang Gao Jan 2008

A Computational Study Of Quasi-2d Flows At Low Reynolds Numbers, Haiyang Gao

Retrospective Theses and Dissertations

Previous studies on low Reynolds number quasi-2D flow around airfoils were mostly two-dimensional, with issues for stalling behavior at higher angles of attack (AOAs). In the present work, a computational study was conducted to investigate the unsteady quasi-2D flow around a streamlined NASA low-speed GA(W)-1 airfoil and a corrugated dragonfly airfoil at the Reynolds numbers of 68,000 and 55,000 with both 2D and 3D simulations. These simulations were carried out by solving the unsteady 2D and 3D Navier-Stokes equations to predict the behavior of the unsteady flow structures around the airfoils at different AOAs. Extensive comparisons ...