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Retrospective Theses and Dissertations

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Full-Text Articles in Engineering

Polymer Chemistry Effects On Protein Release And Immune Activation, Senja Katarina Lopac Jan 2008

Polymer Chemistry Effects On Protein Release And Immune Activation, Senja Katarina Lopac

Retrospective Theses and Dissertations

The objective was to study the chemistry effect on protein release and stabilization and on immune cell activation using polyanhydrides. The two goals were to: (1) Determine how polyanhydride chemistry and fabrication methods affect the release kinetics of proteins from microspheres and the stability of the released protein. Microspheres were fabricated using two non-aqueous methods: solid/oil/oil and cryogenic atomization. Studies found no significant difference in release kinetics of ovalbumin. The more hydrophilic polyanhydrides showed more favorable protein stability, preserving both the immunological epitopes and the primary structure. (2) Investigate the surface marker expression of CD86, CD40, DC SIGN ...


Investigation Into The Stress Assisted Damage Of Copper Surface Under Single Asperity: Influence Of Contact Pressures, Surfaces Stress States And Environments, Bun Hiong Chua Jan 2008

Investigation Into The Stress Assisted Damage Of Copper Surface Under Single Asperity: Influence Of Contact Pressures, Surfaces Stress States And Environments, Bun Hiong Chua

Retrospective Theses and Dissertations

An experiment setup was used to investigate the effects of contact loads, surface stress state and surface environment on dissolution and damage of copper surface. A range of surface stress state was generated with a four-point-bending setup on a well-polished copper sample. Single asperity contact was investigated using the cantilever tip of an Atomic Force Microscope. Controlled tip contact pressures were applied on the copper surface to mechanically stimulate the stressed surface. The experiment was performed in different environments to determine the chemical effects. Volume of material removed during the process was measured to determine material removal rate as 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 ...


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.


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 ...


Experimental And Simulation Study Of Demand Controlled Ventilation, Li Zhang Jan 2008

Experimental And Simulation Study Of Demand Controlled Ventilation, Li Zhang

Retrospective Theses and Dissertations

The purpose of this study is to compare energy use and CO 2 concentration for a multizone building utilizing three ventilation control strategies. The three strategies are occupancy-based demand controlled ventilation (DCV), carbon-dioxide based DCV and constant ventilation. The study compares the building's energy consumption using the three methods for summer, winter and transition seasons. To perform the study, an indoor air quality (IAQ) model was developed and used in conjunction with EnergyPlus to simulate the building. Experiments were conducted at the Iowa Energy Center's Energy Resource Station to validate the IAQ model. Results from the study show ...


Analysis Of A Ddgs Air-Drying System With Heat Recovery, Christopher Brady Hoeck Jan 2008

Analysis Of A Ddgs Air-Drying System With Heat Recovery, Christopher Brady Hoeck

Retrospective Theses and Dissertations

Dry Distiller Grains with Soluble (DDGS) are a co-product of the conversion from corn into Ethanol fuel. Several applications depend on the ability of a drying process to remove moisture from a product, such as DDGS, in an effective and economical manner. Common drying methods use air to facilitate product drying as it proficiently absorbs the unwanted moisture, creating a moist-air mixture that captures both the latent and sensible heat released from the product. The most economical approach to an Air Drying System integrates a heat recovery system that transfers the heat removed by the moist-air mixture during drying back ...


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 ...


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 ...


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 ...


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 ...


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 ...


Thin Water Films Driven By Air Through Surface Roughness, Guoqing Wang Jan 2008

Thin Water Films Driven By Air Through Surface Roughness, Guoqing Wang

Retrospective Theses and Dissertations

The interaction between thin films and roughness surfaces has been studied when the thin viscosity-dominated films are driven by the air shear stress in the context of a high Reynolds number boundary layer theory. A number of properties of this model are examined, such as transport and pooling of water in a roughness field, heat transfer of film/roughness combinations, and rivulet formation. For rivulet formation due to the instability of two-dimensional film fronts, a general formula for the largest unstable wavelength, the fastest temporal growth rate, and the neutral wavelength has been developed from the linear instability analysis. This ...


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 ...


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 ...


Devising A More Robust Automated Detection Method Using Audio Frequency Spectra, Gregory Stargell Jan 2008

Devising A More Robust Automated Detection Method Using Audio Frequency Spectra, Gregory Stargell

Retrospective Theses and Dissertations

The space shuttle, Columbia had a suitcase piece of the SOFI strike the wing of the shuttle causing its demise. Detection methods were evaluated to detect defects in the foam. One of the methods being free field acoustics was explored. Previous works were done in this area, and it showed promise as it was able to detect defects. However all defects or the defects that had significance to the eye was not detected. The method developed before is looked into and was improved upon addressing the problems. Developing a baseline curve and region to compare the data would be two ...


Energy Comparison Of Under Floor Air Distribution Heating Ventilation And Air Conditioning Systems In Office Buildings, Jonathon Richard Giles Jan 2008

Energy Comparison Of Under Floor Air Distribution Heating Ventilation And Air Conditioning Systems In Office Buildings, Jonathon Richard Giles

Retrospective Theses and Dissertations

The purpose of this paper is to compare energy consumption with under floor air distribution systems for office buildings, specifically a call center application.;The building being modeled will have an HVAC system that utilizes an underfloor air distribution system (UFAD). This type of system allows air to be introduced into the plenum space under the floor. The air comes up through the floor into the space through plenum space pressurization. The air is then taken out of the space up high and returned back to the air handling unit.;The three systems reviewed for delivery of the air to ...


Effects Of Computer Self-Efficacy And Spatial Visualization Ability On Student Perceptions Of 2d/3d Cad Virtual Prototype Simulations For Apparel Design, Sandra Stewart Jan 2008

Effects Of Computer Self-Efficacy And Spatial Visualization Ability On Student Perceptions Of 2d/3d Cad Virtual Prototype Simulations For Apparel Design, Sandra Stewart

Retrospective Theses and Dissertations

The ability to visualize three-dimensional (3D) forms from two-dimensional (2D) shapes is critical to apparel designers. While most designers still use traditional techniques to analyze a 3D sample, advances in CAD for apparel design include use of 3D virtual prototypes assembled from 2D pattern data. Textiles and clothing research has examined both 2D CAD and student spatial visualization ability, but no studies compare spatial visualization ability with 3D virtual prototype use in the classroom. Other fields of research have found that a person's computer self-efficacy (CSE) can influence acceptance of a new technology and that spatial visualization ability can ...


Simulating Energy Efficiency In Laboratory Buildings, Robert Marcel Milbrandt Jan 2008

Simulating Energy Efficiency In Laboratory Buildings, Robert Marcel Milbrandt

Retrospective Theses and Dissertations

Today's laboratory buildings are large consumers of energy. The ventilation requirements of these buildings mandate that large quantities of outside air be brought into the building. The advent of air-to-air heat recovery systems has been proven to significantly decrease the energy input needed to condition outside air. This project is a detailed energy simulation of a laboratory building on the campus of Iowa State University in Ames, Iowa. Using Trane TRACE 700 software, a detailed model of the building was created, and energy efficient measures were simulated. These simulations include the proper control of outside air flow rates, the ...


A Static Analysis Of Maximum Wind Penetration In Iowa And A Dynamic Assessment Of Frequency Response In Wind Turbine Types, Eknath Vittal Jan 2008

A Static Analysis Of Maximum Wind Penetration In Iowa And A Dynamic Assessment Of Frequency Response In Wind Turbine Types, Eknath Vittal

Retrospective Theses and Dissertations

As the energy industry moves into the 21st century the use and research into renewable resources has expanded significantly. Whether it is wind, biomass, or solar, the industry is seeking ways to breakthrough and integrate the newest technologies into their power systems. Wind energy, in particular, has seen significant expansion since the 1980's, with generating capability of wind turbines increasing dramatically from 50 kW to nearly 5 MW presently. Seeking to introduce larger levels of wind generation in the Iowa electricity system, the goal of this thesis was to: First, determine the maximum wind penetration level of the existing ...


Energy Efficiency Enhancements To A Low Energy High Performance Building, Joel Clifton Logan Jan 2008

Energy Efficiency Enhancements To A Low Energy High Performance Building, Joel Clifton Logan

Retrospective Theses and Dissertations

This report discusses energy efficiency enhancements made to a low energy, high performance office building. The building studied is the Iowa Association of Municipal Utilities headquarters located in Ankeny, Iowa, just north of Des Moines. Monitoring the energy use of the building for over six years has revealed that it has an average annual site energy use of 29,300 Btu/ft2. This is 68% less energy than that used by the average U.S. office building and 74% less energy than the average office building in climate zone 2, the location of Ankeny.;Three areas of energy use were ...


Characterization Of Geomaterials With X-Ray Computed Tomography (X-Ray Ct), Clinton Halverson Jan 2008

Characterization Of Geomaterials With X-Ray Computed Tomography (X-Ray Ct), Clinton Halverson

Retrospective Theses and Dissertations

The application of 3-dimensional volumetric imaging using non destructive evaluation procedures opens doors in researching geomaterials, allowing study of internal characteristics. X-ray computed tomography (CT) is one such procedure which is especially well suited to geomaterials due to the high density contrasts often found between solid materials and their surrounding environments and/or pore spaces. Although X-ray CT has been applied to geomaterial research in the past, there is a lack of tested X-ray CT methodologies which can be readily applied to many important research tasks. Methods developed and applied herein concern the analyses of soil particle movement during application ...


Metabolic Engineering Of Escherichia Coli For The Efficient Utilization Of Plant Sugar Mixture, Madhuresh Kumar Choudhary Jan 2008

Metabolic Engineering Of Escherichia Coli For The Efficient Utilization Of Plant Sugar Mixture, Madhuresh Kumar Choudhary

Retrospective Theses and Dissertations

In recent years, metabolic flux analysis (MFA) has become an important tool in metabolic engineering. The MFA involves the quantification of intracellular metabolic fluxes in a microorganism. The result of MFA is a metabolic flux map that allows the systematic study of cellular responses to genetic and environmental perturbations. Carbon isotope labeling based MFA, with analysis by NMR or GC/MS, have gained wide use in the metabolic engineering community for estimating metabolic fluxes in central carbon metabolism. We are using MFA as a tool to engineer Escherichia coli sugar utilization regulatory (SURS) for the efficient consumption of sugar mixture ...


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 ...


Decision Making Limitations From Communication Barriers In Government Structures In Chinese Rural Energy Projects, Nathan Gregory Johnson Jan 2008

Decision Making Limitations From Communication Barriers In Government Structures In Chinese Rural Energy Projects, Nathan Gregory Johnson

Retrospective Theses and Dissertations

Field research was conducted in the Li Cheng District (about 1,200 km 2) of Shan Dong Province. Data collection occurred during a two-week period in July 2006. At that time, seven villages represented all relevant sites in the district that contained gasification technologies. Small-group interviews with village leaders, station managers, and community members were conducted locally. Contact with external government agencies and technology scientists completed the set of potential stakeholders.;This study analyzes the failure of state-owned energy development initiatives in China. Communication barriers in bureaucratic structures and culturally prescribed patterns of interaction were revealed as inhibiting information transfer ...


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 ...


Condenser: A Custom Tool For Capturing And Summarizing Network Traffic For Avalanche And Iseage, Jason Charles Maughan Jan 2008

Condenser: A Custom Tool For Capturing And Summarizing Network Traffic For Avalanche And Iseage, Jason Charles Maughan

Retrospective Theses and Dissertations

The Cyber-world is becoming an environment that is increasingly plagued by botnets and other programs adept at creating distributed and flooding-based attacks. These forms of assault are currently some of the most feared types of attacks being faced by networks.;The Internet Scale Event and Attack Generation Environment (ISEAGE) at Iowa State University, has been established to help researchers study actions and events that happen on the Internet. ISEAGE uses a custom tool, AVALANCHE, to simulate distributed and flooding-based attacks. While AVALANCHE is able to launch large quantities of attack packets, its ability to react and handle the enormity of ...


Experimental Simulation Of Atmospheric Boundary Layers And Extreme Gust Events, Emily C. Jones Jan 2008

Experimental Simulation Of Atmospheric Boundary Layers And Extreme Gust Events, Emily C. Jones

Retrospective Theses and Dissertations

Atmospheric boundary layers for open, suburban, and urban terrain were simulated in the Iowa State University Aerodynamic-Atmospheric Boundary Layer (AABL) Wind and Gust Tunnel using stationary turbulence generating obstacles. The individual and combined effects of the obstacles were analyzed in order to simplify the simulation of additional boundary layers in the future.;The mechanical bypass duct gusting system of the AABL facility was used to generate various gusts within smooth and turbulent flows. An exploration of the gust-generating system led to the selection of types of gusts that were studied further. Analysis of the gust velocity data using wavelet theory ...


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 ...