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Retrospective Theses and Dissertations

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Full-Text Articles in Engineering

The Role Of Information Flow In Engineering Optimization, Steven Michael Corns Jan 2008

The Role Of Information Flow In Engineering Optimization, Steven Michael Corns

Retrospective Theses and Dissertations

Current optimization techniques work well for single components represented by a single model. However, many of the problems we face today are multi-disciplinary problems requiring the integration of complex models from different fields to gain a more complete understanding of the overall performance of a biological, engineering, or human system. One example is a modern automobile. Multiple systems (such as the power train and electronic engine control system) are designed and built from various assemblies and components, all of which are then integrated into one final product. This design process evokes a systems-of-systems concept that is also found in agricultural ...


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 ...


An Adaptive Quadrature-Free Implementation Of The High-Order Spectral Volume Method On Unstructured Grids, Robert Evan Harris Jan 2008

An Adaptive Quadrature-Free Implementation Of The High-Order Spectral Volume Method On Unstructured Grids, Robert Evan Harris

Retrospective Theses and Dissertations

An efficient implementation of the high-order spectral volume (SV) method is presented for multi-dimensional conservation laws on unstructured grids. In the SV method, each simplex cell is called a spectral volume (SV), and the SV is further subdivided into polygonal (2D), or polyhedral (3D) control volumes (CVs) to support high-order data reconstructions. In the traditional implementation, Gauss quadrature formulas are used to approximate the flux integrals on all faces. In the new approach, a nodal set is selected and used to reconstruct a high-order polynomial approximation for the flux vector, and then the flux integrals on the internal faces are ...


Beyond The Arithmetic Constraint: Depth-Optimal Mapping Of Logic Chains In Reconfigurable Fabrics, Michael Todd Frederick Jan 2008

Beyond The Arithmetic Constraint: Depth-Optimal Mapping Of Logic Chains In Reconfigurable Fabrics, Michael Todd Frederick

Retrospective Theses and Dissertations

Look-up table based FPGAs have migrated from a niche technology for design prototyping to a valuable end-product component and, in some cases, a replacement for general purpose processors and ASICs alike. One way architects have bridged the performance gap between FPGAs and ASICs is through the inclusion of specialized components such as multipliers, RAM modules, and microcontrollers. Another dedicated structure that has become standard in reconfigurable fabrics is the arithmetic carry chain. Currently, it is only used to map arithmetic operations as identified by HDL macros. For non-arithmetic operations, it is an idle but potentially powerful resource.;Obstacles to using ...


The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick Jan 2008

The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick

Retrospective Theses and Dissertations

Corn stover represents a potential lignocellulosic feedstock that may benefit the emerging cellulosic ethanol industry. This study was conducted to determine dry matter yield and quality characteristics of maize stover, cob, and husk plant fractions, and to make predictions of potential ethanol yields. Detergent fiber predictions were made for each plant fraction using near infrared reflectance spectroscopy (NIRS). Predicted values were used to determine ethanol potential using a modified version of the National Renewable Energy Lab (NREL) theoretical ethanol yield calculator. Although significant, not as much variation was present among genotypes and plant fractions for chemical composition as for dry ...


Improving Pavement Marking Performance Through Contrasting New Methods To Quantify Marking Presence And Increasing Installation Efficiencies Through An Evaluation Of Prototype Bead Guns, Craig Michael Mizera Jan 2008

Improving Pavement Marking Performance Through Contrasting New Methods To Quantify Marking Presence And Increasing Installation Efficiencies Through An Evaluation Of Prototype Bead Guns, Craig Michael Mizera

Retrospective Theses and Dissertations

Agencies continue to search for ways to measure and improve pavement marking performance. With regard to measuring performance this research first conducted a comparative study on the pavement marking evaluation process through a comparison of subjective and objective pavement marking durability rating techniques. The subjective and objective performance evaluation processes reported slight differences. In an effort to address pavement marking quality and efficiencies during installation another study was conducted to develop a methodology for evaluating different bead guns used in the pavement marking application process. An experiment evaluated the performance of the bead guns at various speeds. The SpeedBeader(TM ...


Purification And Characterization Of Recombinant Collagens/Gelatins From Transgenic Corn Seeds, Cheng Zhang Jan 2008

Purification And Characterization Of Recombinant Collagens/Gelatins From Transgenic Corn Seeds, Cheng Zhang

Retrospective Theses and Dissertations

Corn offers a number of advantages as production host for low- and intermediate-value protein-based products that could be produced in large volume as co-products of corn based biorefining. We selected one such potential product, a recombinant human 100 kDa type I collagen alpha 1 (CIalpha1) and a 44 kDa single chain fragment (a gelatin). The equivalency to the intended product was established by characterizing the immunorecognition, molecular weight, amino acid composition and sequence, and post-translational modifications.;Purification for characterization of the recombinant proteins from transgenic corn grain began with protein extraction in 0.1M phosphoric acid buffer. The use of ...


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 ...


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 ...


Swine Wastewater Treatment By The Static Granular Bed Reactor, Seung Joo Lim Jan 2008

Swine Wastewater Treatment By The Static Granular Bed Reactor, Seung Joo Lim

Retrospective Theses and Dissertations

Swine wastewater was successfully treated by the SGBR. Two types of swine wastewater samples were used, and the performance of the SGBR was excellent. COD removal efficiency of sample 1 was 84.7∼94.5%, while that of sample 2 was 58.4∼76.6%. The SGBR acted not only as a bioreactor but also as a filter system. The performance of suspended solids removal was excellent irrespective of the OLR. Additionally, the COD removal efficiency in the effluent after backwashing was not a function of the recovery time but that of the OLR.;The SGBR model was developed with ...


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 ...


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 ...


Utility Cut Repair Techniques: Investigation Of Improved Utility Cut Repair Techniques To Reduce Settlement In Repaired Areas, Phase Ii, Kathlyn A. Videkovich Jan 2008

Utility Cut Repair Techniques: Investigation Of Improved Utility Cut Repair Techniques To Reduce Settlement In Repaired Areas, Phase Ii, Kathlyn A. Videkovich

Retrospective Theses and Dissertations

Trench maintenance problems are caused by improper backfill placement and construction procedures. This thesis is part of a multi-phase research project that aims to improve long-term performance of utility cut restoration trenches. The goal of this research is to improve pavement patch life and reduce the maintenance of the repaired areas. The objectives were to use field-testing data, laboratory testing data, and long-term monitoring (elevation survey and FWD testing) to suggest and modify recommendations from Phase I and to identify the principles of trench subsurface settlement and load distribution in utility cut restoration areas by using instrumented trenches. The objectives ...


Evaluation Of An Anaerobic Granule Biosensor For Upset Early Warning Detection, Xi Jiang Jan 2008

Evaluation Of An Anaerobic Granule Biosensor For Upset Early Warning Detection, Xi Jiang

Retrospective Theses and Dissertations

In this study a porous pot reactor was used to simulate an activated sludge stage and an anaerobic granule biosensor (AGB), as an upset early warning system for activated sludge treatment process, was configured in a down-flow mode with a side-stream of the influent wastewater fed to the top. The hydraulic retention time (HRT) for the porous pot and AGB systems was 12 hours and 6 hours, respectively. The influent was made up of synthetic wastewater. In the first group of toxic loading tests, the prepared cupric chloride solutions were separately injected into both the porous pot and AGB systems ...


Crystallization Of Zr₂Pd(Subscript X)Cu(₁₋(Subscript X)) And Zr₂Ni(Subscript X)Cu(₁₋(Subscript X)) Metallic Glass, Min Xu Jan 2008

Crystallization Of Zr₂Pd(Subscript X)Cu(₁₋(Subscript X)) And Zr₂Ni(Subscript X)Cu(₁₋(Subscript X)) Metallic Glass, Min Xu

Retrospective Theses and Dissertations

One interesting aspect of metallic glasses is the numerous instances of the deviation of the phase selection from the amorphous state to thermodynamically stable phases during the crystallization process. Their devitrification pathways allow us to study the relationship between the original amorphous structure and their crystalline counter parts. Among the various factors of phase selections, size and electronic effects have been most extensively studied. Elucidating the phase selection process of a glassy alloy will be helpful to fill in the puzzle of the changes from disordered to ordered structures. In this thesis, Two model Zr2PdxCu(1-x) and Zr2NixCu(1-x) (x ...


Identification, Evaluation And Quantification Of Vocs As Biosecure Markers Of Swine Carcass Degradation, Neslihan Akdeniz Jan 2008

Identification, Evaluation And Quantification Of Vocs As Biosecure Markers Of Swine Carcass Degradation, Neslihan Akdeniz

Retrospective Theses and Dissertations

Swine carcasses were composted using passively-aerated composting system designed by the Canadian Food Inspection Agency during the 2004 Avian influenza outbreak in British Columbia. In this system, swine carcasses were fully covered by plastic sheets due to biosecurity concerns and visual inspection of the swine carcasses was impossible. Monitoring volatile organic compounds (VOCs) released from carcasses was a promising approach to assess progress and completion of the carcass degradation. In this study, VOCs were sampled using solid phase microextraction (SPME). Samples were analyzed using multidimensional gas chromatography-mass spectrometry (MDGC-MS) (a) to develop a comprehensive chemical library of volatile organic compounds ...


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 ...


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 ...


Improving Solution Characteristics Of Particle Swarm Optimization Through The Use Of Digital Pheromones, Parallelization, And Graphical Processing Units (Gpus), Vijay Kiran Kalivarapu Jan 2008

Improving Solution Characteristics Of Particle Swarm Optimization Through The Use Of Digital Pheromones, Parallelization, And Graphical Processing Units (Gpus), Vijay Kiran Kalivarapu

Retrospective Theses and Dissertations

Deterministic optimization methods such as steepest descent, conjugate gradient and Newton's methods are known for their robustness in iteratively reducing the objective function value for minimization problems. However, they are primarily suitable for solving single objective function problems that are unimodal and continuous. With increased sophistication in engineering problems, multimodal and multi-objective problems have become more prevalent drastically reducing the effectiveness of deterministic methods. This led to the development of heuristic methods, particularly evolutionary methods such as Genetic Algorithms, Ant Colony Optimization, and Particle Swarm Optimization. These methods have multiple design points exploring the design space over iterations as ...


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 ...


Analysis Of Transmit Beamforming And Fair Ofdma Scheduling, Alex Leith Jan 2008

Analysis Of Transmit Beamforming And Fair Ofdma Scheduling, Alex Leith

Retrospective Theses and Dissertations

Two promising candidates for beyond 3rd generation (B3G) and 4G communication standards are multiple input multiple output (MIMO) and orthogonal frequency division multiple access (OFDMA) systems. OFDMA is a new technique that enables multiple users to transmit parallel data streams, allowing a much higher data rate than conventional systems, such as time division multiple access (TDMA) or code division multiple access (CDMA). Another research topic involving MIMO systems use antenna arrays at both the transmitter and the receiver. By using multiple antennas, the transmitter can adapt to the channel as it varies across time. This is accomplished by using a ...


Analysis Of Jointed Plain Concrete Pavement Systems With Nondestructive Test Results Using Artificial Neural Networks, Mustafa Birkan Bayrak Jan 2008

Analysis Of Jointed Plain Concrete Pavement Systems With Nondestructive Test Results Using Artificial Neural Networks, Mustafa Birkan Bayrak

Retrospective Theses and Dissertations

The primary goal of this research was to show that artificial neural network (ANN) models could be developed to perform rapid and accurate predictions of jointed plain concrete pavement system (JPCP) parameters which will enable pavement engineers to incorporate the state-of-the-art finite element (FE) solutions into routine practical design. The ISLAB2000 finite element program has been used as an advanced structural model for solving the responses of the concrete pavement systems and generating a large knowledge database.;Totally, fifty-six ANN-based backcalculation and forward calculation models were developed as part of this research for the analysis of JPCP systems under traffic ...


Performance-Based Seismic Analysis And Design Improvements Of Two Precast Concrete Structural Systems, Mohammad Ataur Rahman Jan 2008

Performance-Based Seismic Analysis And Design Improvements Of Two Precast Concrete Structural Systems, Mohammad Ataur Rahman

Retrospective Theses and Dissertations

This study focuses on the multiple-level seismic performance in terms of structural and non-structural damages of precast hybrid frame and jointed precast post-tensioned wall systems through dynamic analysis of precast buildings subjected to spectrum compatible ground motions of various intensities. The maximum transient interstory drift, residual interstory drift and floor acceleration are considered as acceptance criteria for evaluating seismic performance of these systems subjected by four levels of ground motions. Interstory drift and floor acceleration are directly related to structural and non-structural damages, respectively. Two dimensional non-linear finite element analytical models for hybrid frames and jointed wall systems used in ...


Evaluation Of Bridges Implementing Innovative Materials And Design, Mark Thomas Giesmann Jan 2008

Evaluation Of Bridges Implementing Innovative Materials And Design, Mark Thomas Giesmann

Retrospective Theses and Dissertations

Concrete bridge decks exposed to harsh temperatures and a variety of deicing chemicals are suspect to deterioration caused by corrosion of the steel reinforcement. By removing the steel reinforcement within the concrete slab, the life expectancy and durability of the bridge deck can be expected to improve greatly [1]. Researchers at the Bridge Engineering Center at Iowa State University have researched, designed, and tested the first known bridge in the United States that has implemented a steel-free deck (SFD) system. The bridge deck consists of a fiber reinforced deck with no internal reinforcing steel that is composite with the steel ...


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 ...


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 ...


Manufacturability Analysis For Non-Feature-Based Objects, Ye Li Jan 2008

Manufacturability Analysis For Non-Feature-Based Objects, Ye Li

Retrospective Theses and Dissertations

This dissertation presents a general methodology for evaluating key manufacturability indicators using an approach that does not require feature recognition, or feature-based design input. The contributions involve methods for computing three manufacturability indicators that can be applied in a hierarchical manner. The analysis begins with the computation of visibility, which determines the potential manufacturability of a part using material removal processes such as CNC machining. This manufacturability indicator is purely based on accessibility, without considering the actual machine setup and tooling. Then, the analysis becomes more specific by analyzing the complexity in setup planning for the part; i.e. how ...


Study Of Left-Handed Materials, Jiangfeng Zhou Jan 2008

Study Of Left-Handed Materials, Jiangfeng Zhou

Retrospective Theses and Dissertations

Left handed materials (LHMs) are artificial materials that have negative electrical permittivity, negative magnetic permeability, and negative index of refraction across a common frequency band. They possess electromagnetic (EM) properties not found in nature. LHMs have attracted tremendous attention because of their potential applications to build the perfect lens and cloaking devices. In the past few years there has been ample proof for the existence of LHMs in the microwave frequency range. Recently, researchers are trying hard to push the operating frequency of LHMs into terahertz and the optical regime.;In this thesis, we start with the theoretical prediction of ...


The Effects Of Low Pressure Helium Ion Bombardment On Hydrogenated Amorphous Silicon, Michael William Beckman Jan 2008

The Effects Of Low Pressure Helium Ion Bombardment On Hydrogenated Amorphous Silicon, Michael William Beckman

Retrospective Theses and Dissertations

The benefits of low pressure Plasma Enhanced Chemical Vapor Deposition (PECVD) using helium as the dilutant gas were investigated in a variety of conditions to identify the techniques feasibility as a low band gap material yielding deposition method. Films and photovoltaic devices with intrinsic layers processed at lower pressures with helium dilution are thought to possess improved characteristics with lower hydrogen content and lowered optical band gaps. When films are grown at lower pressures in the presence of helium the optical band gap tends to decrease. Amorphous silicon a-Si:H generally has a band gap around 1.75eV. This work ...


Light-Trapping Enhancement In Thin Film Solar Cells With Photonic Crystals, Dayu Zhou Jan 2008

Light-Trapping Enhancement In Thin Film Solar Cells With Photonic Crystals, Dayu Zhou

Retrospective Theses and Dissertations

Photovoltaics (or solar cell) has been an active area for research and development, driven by the world's constantly increasing needs for power. Among the current solar technologies, thin film solar cell promises lower cost, but at the expense of lower power conversion efficiency. The efficiency of thin film solar cell can be improved using light confinement schemes commonly referred to as light-trapping. In this thesis, we develop novel light-trapping schemes utilizing photonic crystals (PCs). The optical modeling is performed with a rigorous scattering matrix approach, where Maxwell's equations are solved in Fourier space, and simulations are carried out ...