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2008

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Articles 3931 - 3960 of 4190

Full-Text Articles in Engineering

Parameter Estimation And Life Modeling Of Lithium-Ion Cells, Shriram Santhanagopalan, Qi Zhang, Karthikeyan Kumaresan, Ralph E. White Jan 2008

Parameter Estimation And Life Modeling Of Lithium-Ion Cells, Shriram Santhanagopalan, Qi Zhang, Karthikeyan Kumaresan, Ralph E. White

Faculty Publications

Lithium-ion pouch cells were cycled at five different temperatures (5, 15, 25, 35, and 45°C ), and rate capability studies were performed after every hundred cycles. The data were used with a simple physics-based model to estimate parameters that capture the capacity fade in the cell, with cycling. The weight of active material within each electrode was estimated as a function of time, using rate capability data at the C/33 rate. The C-rate for these cells is 1.656 A. The capacity fade due to the loss of active material and that due to the loss of cyclable lithium …

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Thermal Model For A Li-Ion Cell, Karthikeyan Kumaresan, Godfrey Sikha, Ralph E. White Jan 2008

Thermal Model For A Li-Ion Cell, Karthikeyan Kumaresan, Godfrey Sikha, Ralph E. White

Faculty Publications

A thermal model for a lithium-ion cell is presented and used to predict discharge performance at different operating temperatures. The results from the simulations are compared to experimental data obtained from lithium-ion pouch cells. The model includes a set of parameters (and their concentration and temperature dependencies) that has been obtained for a lithium-ion cell composed of a mesocarbon microbead anode, LiCoO2 cathode in 1 M LiPF6 salt, in a mixture of ethylene carbonate, propylene carbonate, ethyl-methyl carbonate, and diethyl carbonate electrolyte. The parameter set was obtained by comparing the model predictions to the experimental discharge profiles obtained …

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Analytical Expression For The Impedance Response For A Lithium-Ion Cell, Godfrey Sikha, Ralph E. White Jan 2008

Analytical Expression For The Impedance Response For A Lithium-Ion Cell, Godfrey Sikha, Ralph E. White

Faculty Publications

An analytical expression to predict the impedance response of a dual insertion electrode cell (insertion electrodes separated by an ionically conducting membrane) is presented. The expression accounts for the reaction kinetics and double-layer adsorption processes at the electrode-electrolyte interface, transport of electroactive species in the electrolyte phase, and insertion of species in the solid phase of the insertion electrodes. The accuracy of the analytical expression is validated by comparing the impedance response predicted by the expression to the corresponding numerical solution. The analytical expression is used to predict the impedance response of a lithium-ion cell consisting of a porous LiCoO …

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A Mathematical Model For A Lithium–Sulfur Cell, Karthikeyan Kumaresan, Yuriy Mikhaylik, Ralph E. White Jan 2008

A Mathematical Model For A Lithium–Sulfur Cell, Karthikeyan Kumaresan, Yuriy Mikhaylik, Ralph E. White

Faculty Publications

A mathematical model is presented for a complete lithium–sulfur cell. The model includes various electrochemical and chemical (precipitation) reactions, multicomponent transport phenomena in the electrolyte, and the charge transfer within and between solid and liquid phases. A change in the porosity of the porous cathode and separator due to precipitation reactions is also included in the model. The model is used to explain the physical reasons for the two-stage discharge profiles that are typically obtained for lithium–sulfur cells.

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Construction, Installation, And Performance Of Two Repacked Weighing Lysimeters, José O. Payero, Suat Irmak Jan 2008

Construction, Installation, And Performance Of Two Repacked Weighing Lysimeters, José O. Payero, Suat Irmak

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Weighing lysimeters are the standard method for directly measuring evapotranspiration (ET). This paper discusses the construction, installation, and performance of two (1.52 m × 1.52 m × 2.13-m deep) repacked weighing lysimeters for measuring ET of corn and soybean in West Central Nebraska. The cost of constructing and installing each lysimeter was approximately US $12,500, which could vary depending on the availability and cost of equipment and labor. The resolution of the lysimeters was 0.0001 mV V-1, which was limited by the data processing and storage resolution of the datalogger. This resolution was equivalent to 0.064 and 0.078 …

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Variability Analyses Of Alfalfa-Reference To Grass-Reference Evapotranspiration Ratios In Growing And Dormant Seasons, Suat Irmak, Ayse Kilic, T. A. Howell, Derrel Martin, J. O. Payero, K. S. Copeland Jan 2008

Variability Analyses Of Alfalfa-Reference To Grass-Reference Evapotranspiration Ratios In Growing And Dormant Seasons, Suat Irmak, Ayse Kilic, T. A. Howell, Derrel Martin, J. O. Payero, K. S. Copeland

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Alfalfa-reference evapotranspiration (ETr) values sometimes need to be converted to grass-reference ET (ETo), or vice versa, to enable crop coefficients developed for one reference surface to be used with the other. However, guidelines to make these conversions are lacking. The objectives of this study were to: (1) develop ETr to ETo ratios (Kr values) for different climatic regions for the growing season and nongrowing (dormant) seasons; and (2) determine the seasonal behavior of Kr values between the locations and in the same location for different seasons. Monthly average Kr values …

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Surface Polyethylene Glycol Enhances Substrate-Mediated Gene Delivery By Nonspecifically Immobilized Complexes, Angela K. Pannier, Julie A. Wieland, Lonnie D Shea Jan 2008

Surface Polyethylene Glycol Enhances Substrate-Mediated Gene Delivery By Nonspecifically Immobilized Complexes, Angela K. Pannier, Julie A. Wieland, Lonnie D Shea

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Substrate-mediated gene delivery describes the immobilization of gene therapy vectors to a biomaterial, which enhances gene transfer by exposing adhered cells to elevated DNA concentrations within the local microenvironment. Surface chemistry has been shown to affect transfection by nonspecifically immobilized complexes using self-assembled monolayers (SAMs) of alkanethiols on gold. In this report, SAMs were again used to provide a controlled surface to investigate whether the presence of oligo(ethylene glycol) (EG) groups in a SAM could affect complex morphology and enhance transfection. EG groups were included at percentages that did not affect cell adhesion. Nonspecific complex immobilization to SAMs containing combinations …

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Nanostructured Engineered Materials With High Magneto-Optic Performance For Integrated Photonics Applications, Mikhail Vasiliev, Kamal Alameh, Viatcheslav A. Kotov, Y T. Lee Jan 2008

Nanostructured Engineered Materials With High Magneto-Optic Performance For Integrated Photonics Applications, Mikhail Vasiliev, Kamal Alameh, Viatcheslav A. Kotov, Y T. Lee

School of Engineering Publications

In this paper, we experimentally investigate the performance of a set of technologies used for the deposition, annealing and characterization of high-performance magnetooptic rare-earth-doped garnet materials and all-garnet heterostructures for use in photonic crystals and novel integrated-optics devices.

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New Insights Into The Controls And Mechanisms Of Plankton Productivity Along The Us West Coast, Raphael M. Kudela, Neil S. Banas, John A. Barth, Elizabeth R. Frame, David A. Jay, John L. Largier, Evelyn J. Lessard, Tawnya D. Peterson, Andrea J. Vander Woude Jan 2008

New Insights Into The Controls And Mechanisms Of Plankton Productivity Along The Us West Coast, Raphael M. Kudela, Neil S. Banas, John A. Barth, Elizabeth R. Frame, David A. Jay, John L. Largier, Evelyn J. Lessard, Tawnya D. Peterson, Andrea J. Vander Woude

Civil and Environmental Engineering Faculty Publications and Presentations

During the lifetime of the National Science Foundation's Coastal Ocean Processes program, four experiments were conducted on the US West Coast in the northern California Current System. Although each project had a unique scientific focus, all four addressed the mechanisms causing eastern boundary current systems in general, and the California Current System in particular, to be biologically rich, from phytoplankton to apex predators. Taken together, findings from these projects provide new insights into the canonical view that upwelling systems are simple wind-driven "conveyor belts," bringing cold, nutrient-rich waters to the well-lit surface ocean where biological organisms flourish. We highlight new …

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Daily Forecasts Of Columbia River Plume Circulation: A Tale Of Spring/Summer Cruises, Yinglong J. Zhang, Antonio M. Baptista, Barbara M. Hickey, Byron C. Crump, David A. Jay, Michael Wilkin, Charles Seaton Jan 2008

Daily Forecasts Of Columbia River Plume Circulation: A Tale Of Spring/Summer Cruises, Yinglong J. Zhang, Antonio M. Baptista, Barbara M. Hickey, Byron C. Crump, David A. Jay, Michael Wilkin, Charles Seaton

Civil and Environmental Engineering Faculty Publications and Presentations

Semi-operational daily forecasts of circulation from an observatory for the Columbia River estuary-plume-shelf system routinely support oceanographic cruises, by providing 24h-ahead estimates of plume location and structure for planning purposes and for near real-time interpretation of observations. This paper analyzes forecast skill during spring/summer cruises in 2004-2007. Assessment addresses both qualitative descriptions of major plume trends and features and quantitative representation of data from (primarily) vessel-based flow-through, cast and towed systems. Forecasts emerge as robust predictors of plume location and variability, with skill that has grown over time, at least in part due to improvements in model algorithms. When the …

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Seasonal Variability And Estuary-Shelf Interactions In Circulation Dynamics Of A River-Dominated Estuary, Arun Chawla, David A. Jay, Antonio M. Baptista, Michael Wilkin, Charles Seaton Jan 2008

Seasonal Variability And Estuary-Shelf Interactions In Circulation Dynamics Of A River-Dominated Estuary, Arun Chawla, David A. Jay, Antonio M. Baptista, Michael Wilkin, Charles Seaton

Civil and Environmental Engineering Faculty Publications and Presentations

The long-term response of circulation processes to external forcing has been quantified for the Columbia River estuary using in situ data from an existing coastal observatory. Circulation patterns were determined from four Acoustic Doppler Profilers (ADP) and several conductivity-temperature sensors placed in the two main channels. Because of the very strong river discharge, baroclinic processes play a crucial role in the circulation dynamics, and the interaction of the tidal and subtidal baroclinic pressure gradients plays a major role in structuring the velocity field. The input of river flow and the resulting low-frequency flow dynamics in the two channels are quite …

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Combining Climate, Crash, And Highway Data For Improved Ranking Of Speed And Winter-Weather Related Crash Locations In Oregon, Christopher M. Monsere, Peter G. Bosa, Robert L. Bertini Jan 2008

Combining Climate, Crash, And Highway Data For Improved Ranking Of Speed And Winter-Weather Related Crash Locations In Oregon, Christopher M. Monsere, Peter G. Bosa, Robert L. Bertini

Civil and Environmental Engineering Faculty Publications and Presentations

In recent years, the techniques for screening transportation networks to identify high crash locations have become more sophisticated. Many transportation agencies, however, lack sufficient data, either in timeliness, completeness, or accuracy to implement many of the recent advances. This paper presents the results of an empirical analysis of screening and ranking for specific crash type (speed and ice related crashes) on rural 1.6 km (1 mi) highway sections of Oregon highways. The analysis includes data generated with the extensive use of spatial techniques and incorporates climate data to enhance environmental considerations. The paper compares the results of five ranking methods—critical …

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Suspended Sediment Fluxes At An Intertidal Flat: The Shifting Influence Of Wave, Wind, Tidal, And Freshwater Forcing, Stefan A. Talke, Mark T. Stacey Jan 2008

Suspended Sediment Fluxes At An Intertidal Flat: The Shifting Influence Of Wave, Wind, Tidal, And Freshwater Forcing, Stefan A. Talke, Mark T. Stacey

Civil and Environmental Engineering Faculty Publications and Presentations

Using in situ, continuous, high frequency (8–16 Hz) measurements of velocity, suspended sediment concentration (SSC), and salinity, we investigate the factors affecting near-bed sediment flux during and after a meteorological event (cold front) on an intertidal flat in central San Francisco Bay. Hydrodynamic forcing occurs over many frequency bands including wind wave, ocean swell, seiching (500–1000 s), tidal, and infra-tidal frequencies, and varies greatly over the time scale of hours and days. Sediment fluxes occur primarily due to variations in flow and SSC at three different scales: residual (tidally averaged), tidal, and seiching. During the meteorological event, sediment fluxes are …

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New Particle Formation In The Front Range Of The Colorado Rocky Mountains, Micahel Boy, Thomas Karl, Andrew Turnipseed, Roy Lee Mauldin, Edward Kosciuch, James Greenberg, Jeff Rathbone, James Smith, Andreas Held, Kelley Barsanti, Alex Guenther Jan 2008

New Particle Formation In The Front Range Of The Colorado Rocky Mountains, Micahel Boy, Thomas Karl, Andrew Turnipseed, Roy Lee Mauldin, Edward Kosciuch, James Greenberg, Jeff Rathbone, James Smith, Andreas Held, Kelley Barsanti, Alex Guenther

Civil and Environmental Engineering Faculty Publications and Presentations

New particle formation is of interest because of its influence on the properties of aerosol population, and due to the possible contribution of newly formed particles to cloud condensation nuclei. Currently no conclusive evidence exists as to the mechanism or mechanisms of nucleation and subsequent particle growth. However, nucleation rates exhibit a clear dependence on ambient sulphuric acid concentrations and particle growth is often attributed to the condensation of organic vapours. A detailed study of new particle formation in the Front Range of the Colorado Rocky Mountains is presented here. Gas and particle measurement data for 32 days was analyzed …

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Optimal Bus Stop Spacing For Minimizing Transit Operation Cost, Huan Li, Robert L. Bertini Jan 2008

Optimal Bus Stop Spacing For Minimizing Transit Operation Cost, Huan Li, Robert L. Bertini

Civil and Environmental Engineering Faculty Publications and Presentations

With the increasing attention to finance issues relative to transit operation, a bus stop spacing model is generated with the aim at minimizing the operation cost without impact on transit accessibility. Two cost functions are considered in the model including passenger access cost and in-vehicle passenger stopping cost aiming at minimizing total cost. A bus route in Portland, Oregon, USA is examined as an example using Archived Bus Dispatch System (BDS) data provided by TriMet, the regional transit provider for the Portland, Oregon metropolitan area. Based on the optimization model, the theoretical optimized bus stop spacing is 930 feet comparing …

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Vibrations For Improving Multiphase Contact, Yogesh G. Waghmare Jan 2008

Vibrations For Improving Multiphase Contact, Yogesh G. Waghmare

LSU Doctoral Dissertations

Present work demonstrates the use of vibrations to enhance performance of two multi-phase contacting systems: a bubble column for gas-liquid contacting (physical absorption) and a Piston Oscillating Monolith Reactor (POMR) for gas-liquid-solid contacting (catalytic reactions). In a bubble column reactor, enhancements of mass transfer coefficient and gas hold up were experimentally studied for the air-water system. Mass transfer coefficient enhancements up to 500% and gas hold-up improvements up to 200% were achieved under the application of low amplitude (0.5-2.5 mm) vibration at low frequencies (0-25 Hz). A fundamental theory was developed from first principles to explain these enhancements. The theory …

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The Effects Of Nanoscale Disorder On The Paramagnetic To Ferromagnetic Transition In Melt-Spun Gadolinium And Gadolinium Iron Alloys, Justin Gary Bohnet Jan 2008

The Effects Of Nanoscale Disorder On The Paramagnetic To Ferromagnetic Transition In Melt-Spun Gadolinium And Gadolinium Iron Alloys, Justin Gary Bohnet

Honors Program Theses

As nanoscale science continues to flourish, scientists strive to understand how structure and order (or disorder) on the nanoscale contribute to macroscopic properties, such as magnetism. This study examines alloys of gadolinium and iron that have been nanostructured through the process of melt-spinning. The result was a two-part system consisting of small (~70 nm) gadolinium grains surrounded by an amorphous gadolinium and iron matrix. Measurements of the samples’ DC magnetization and AC susceptibility were performed. By looking at the paramagnetic to ferromagnetic transition in the materials, the critical exponents were obtained and used to classify and understand how the addition …

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Exceed Teaching Workshop: Tenth Year Anniversary, Allen Estes, Ronald Welch, Stephen Ressler, Norman Dennis, Debra Larson, Carol Considine, Tonya Nilsson, Jim O'Brien, Thomas Lenox Jan 2008

Exceed Teaching Workshop: Tenth Year Anniversary, Allen Estes, Ronald Welch, Stephen Ressler, Norman Dennis, Debra Larson, Carol Considine, Tonya Nilsson, Jim O'Brien, Thomas Lenox

Engineering Technology Faculty Publications

In response to the need for faculty training, the American Society of Civil Engineers developed and funded the ExCEEd (Excellence in Civil Engineering Education) Teaching Workshop that is today - the summer of 2008 - celebrating its tenth year of existence. For the past decade, nineteen ExCEEd Teaching Workshops (ETW) have been held at the United States Military Academy, the University of Arkansas, and Northern Arizona University, with two more workshops scheduled for this summer for a total of 21 offerings. ETW has realized 449 graduates from 203 different U.S. and international colleges and universities. This paper summarizes the content …

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Design And Develop A Cost Effective Microcontroller Training System For Distance Learning Engineering Students, Steve Hsiung, John Ritz, James Eiland Jan 2008

Design And Develop A Cost Effective Microcontroller Training System For Distance Learning Engineering Students, Steve Hsiung, John Ritz, James Eiland

Engineering Technology Faculty Publications

This is the review of a NSF funded project that addresses the hands-on distance learning needs in microprocessor/microcontroller related courses. A research team designed a low cost training system with supporting instructional materials to assist the teaching of these concepts. Individual laboratory activities are being developed to reinforce student learning and skill development in programming concepts. This basic system format eventually will support an array of technology courses. This project involves two community colleges, Blue Ridge Community College (BRCC), VA and Olympic College (OC), WA, and a four-year university, Old Dominion University (ODU), VA, in a collaborative research team to …

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An Integrated Simulation Design With Three-Dimensional Motions And A Hydraulic Stewart Simulator, Cheng Lin, Gene Hou, Yuzhong Shen, Hector Garcia Jan 2008

An Integrated Simulation Design With Three-Dimensional Motions And A Hydraulic Stewart Simulator, Cheng Lin, Gene Hou, Yuzhong Shen, Hector Garcia

Engineering Technology Faculty Publications

This paper presents an integrated design process and tests of a Stewart simulator with a virtual visualization tool, which uses Virtools to create and generate three-dimensional motions. An inverse kinematic algorithm is written to convert each visualized motion to the displacements of six cylinders in a Stewart motion simulator. Information of the displacements is then transferred through the User Datagram Protocol (UDP) to a personal computer which has the LabVIEW software. An NI USB-6251 data acquisition device is applied to interact with the LabVIEW program and the Stewart hydraulic simulator. The approach presented in this paper to function an old …

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Modular Fast Direct Analysis Using Non-Radiating Local-Global Solution Modes, Xin Xu Jan 2008

Modular Fast Direct Analysis Using Non-Radiating Local-Global Solution Modes, Xin Xu

University of Kentucky Doctoral Dissertations

This dissertation proposes a modular fast direct (MFD) analysis method for a class of problems involving a large fixed platform region and a smaller, variable design region. A modular solution algorithm is obtained by first decomposing the problem geometry into platform and design regions. The two regions are effectively detached from one another using basic equivalence concepts. Equivalence principles allow the total system model to be constructed in terms of independent interaction modules associated with the platform and design regions. These modules include interactions with the equivalent surface that bounds the design region. This dissertation discusses how to analyze (fill …

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Novel Catalysts For The Production Of Co- And Co2-Free Hydrogen And Carbon Nanotubes By Non-Oxidative Dehydrogenation Of Hydrocarbons, Wenqin Shen Jan 2008

Novel Catalysts For The Production Of Co- And Co2-Free Hydrogen And Carbon Nanotubes By Non-Oxidative Dehydrogenation Of Hydrocarbons, Wenqin Shen

University of Kentucky Doctoral Dissertations

Non-oxidative dehydrogenation of hydrocarbons is an attractive alternative route for the production of CO- and CO2-free hydrogen. It will satisfy a major requirement for successful utilization of polymer electrolyte membrane (PEM) fuel cells (< 10 ppm CO) and sequestering carbon as a potentially valuable by-product, carbon nanotubes (CNTs). Due to the deposition of carbon on the surface of catalyst particles during the reaction, catalyst performance, life-time, and purification of the generated carbon product, are significant issues to solve in order to make the process practically feasible. The scope of this thesis includes: the development of novel Fe, Ni, and Fe-Ni catalysts supported on a Mg(Al)O support to achieve improved catalytic performance with easily-purified CNTs; evaluation of catalysts for ethane/methane dehydrogenation at moderate reaction temperatures; and study of activation and deactivation mechanisms by a variety of characterization techniques including TEM, HRTEM, XRD, Mössbauer spectroscopy, and x-ray absorption fine structure (XAFS) spectroscopy. The Mg(Al)O support was prepared by calcination of synthetic MgAl-hydrotalcite with a Mg to Al ratio of 5. The catalysts were prepared either by conventional incipient wetness method or by a novel nanoparticle impregnation method, where the monodisperse catalyst nanoparticles were prepared in advance by thermal decomposition of a metal-organic complex in an organic-phase solution and then dispersed onto the Mg(Al)O support. Dehydrogenation of undiluted methane was conducted in a fix-bed plug-flow reactor. Before reaction, the catalysts were activated by reduction in hydrogen. Fe-based catalysts exhibit a higher hydrogen yield at temperature above 600ºC compared with monometallic Ni catalyst. FeNi-9 nm/Mg(Al)O, Fe-10 nm/Mg(Al)O and Fe-5 nm/ Mg(Al)O nanoparticle catalysts show much improved performance and longer life-times compared with the corresponding FeNi IW/Mg(Al)O and Fe IW/Mg(Al)O catalysts prepared by incipient wetness. 10 nm is the optimum particle size for methane dehydrogenation. Addition of Ni to Fe forming a bimetallic FeNi alloy catalyst enhances the catalytic performance at the temperatures below 650ºC. Metallic Fe, Ni, FeNi alloy and Fe-Ni-C alloy, unstable iron carbide are all catalytically active components. Catalysts deactivation is due to the carbon encapsulation. The carbon products are in the form of stack-cone CNTs (SCNTs) and multi-walled CNTs (MWNTs), depending on the reaction temperature and catalyst composition. The growth of CNTs follows a tip growth mechanism and the purity of cleaned CNTs is more than 99.5%.

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Value Mapping Framework Involving Stakeholders For Supply Chain Improvement When Implementing Information Technology Projects, Karla Moore Jan 2008

Value Mapping Framework Involving Stakeholders For Supply Chain Improvement When Implementing Information Technology Projects, Karla Moore

Electronic Theses and Dissertations

Successful Supply Chain Management (SCM) depends on how well an organization performs internal and external communications with trading partners, executes the logistics component, and understands/monitors related costs of conducting its business. The use of information technology (IT) is considered a prerequisite for the effective control of today's complex supply chains. Increased communication technology has redefined how businesses work together, raised customer expectations, and placed new demands on supply chain performance. IT components with proven and rapid return-on-investment are favored to support critical supply chain processes such as leaner manufacturing processes, consumer-driven supply chains, and customer responsiveness. The use of IT …

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Design Of An Adaptive Autopilot For An Expendable Launch Vehicle, Clinton Plaisted Jan 2008

Design Of An Adaptive Autopilot For An Expendable Launch Vehicle, Clinton Plaisted

Electronic Theses and Dissertations

This study investigates the use of a Model Reference Adaptive Control (MRAC) direct approach to solve the attitude control problem of an Expendable Launch Vehicle (ELV) during its boost phase of flight. The adaptive autopilot design is based on Lyapunov Stability Theory and provides a useful means for controlling the ELV in the presence of environmental and dynamical uncertainties. Several different basis functions are employed to approximate the nonlinear parametric uncertainties in the system dynamics. The control system is designed so that the desire dresponse to a reference model would be tracked by the closed-loop system. The reference model is …

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An Adaptive Multiobjective Evolutionary Approach To Optimize Artmap Neural Networks, Assem Kaylani Jan 2008

An Adaptive Multiobjective Evolutionary Approach To Optimize Artmap Neural Networks, Assem Kaylani

Electronic Theses and Dissertations

This dissertation deals with the evolutionary optimization of ART neural network architectures. ART (adaptive resonance theory) was introduced by a Grossberg in 1976. In the last 20 years (1987-2007) a number of ART neural network architectures were introduced into the literature (Fuzzy ARTMAP (1992), Gaussian ARTMAP (1996 and 1997) and Ellipsoidal ARTMAP (2001)). In this dissertation, we focus on the evolutionary optimization of ART neural network architectures with the intent of optimizing the size and the generalization performance of the ART neural network. A number of researchers have focused on the evolutionary optimization of neural networks, but no research has …

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Prevention Of Environmentally Induced Degradation In Carbon/Epoxy Composite Material Via Implementation Of A Polymer Based Coati, Bradford Tipton Jan 2008

Prevention Of Environmentally Induced Degradation In Carbon/Epoxy Composite Material Via Implementation Of A Polymer Based Coati, Bradford Tipton

Electronic Theses and Dissertations

As the use of fiber reinforced plastics increases in such industries as aerospace, wind energy, and sporting goods, factors effecting long-term durability, such as environmental exposure, are of increasing interest. The primary objectives of this study were to examine the effects of extensive environmental exposure (specifically UV radiation and moisture) on carbon/epoxy composite laminate structures and to determine the relative effectiveness of polymer-based coatings at mitigating degradation incurred due to such exposure. Carbon/epoxy composite specimens, both coated and uncoated, were subjected to accelerated weathering in which prolonged outdoor exposure was simulated by controlling the radiation wavelength (in the UV region), …

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Improving Business Performance Through The Integration Of Human Factors Engineering Into Organizations Using A Systems Engineeri, Monica Philippart Jan 2008

Improving Business Performance Through The Integration Of Human Factors Engineering Into Organizations Using A Systems Engineeri, Monica Philippart

Electronic Theses and Dissertations

Most organizations today understand the valuable contribution employees as people (rather than simply bodies) provide to their overall performance. Although efforts are made to make the most of the human in organizations, there is still much room for improvement. Focus in the reduction of employee injuries such as cumulative trauma disorders rose in the 80 s. Attempts at increasing performance by addressing employee satisfaction through various methods have also been ongoing for several years now. Knowledge Management is one of the most recent attempts at controlling and making the best use of employees knowledge. All of these efforts and more …

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Low Reynolds Number Water Flow Characteristics Through Rectangular Micro Diffusers/Nozzles With A Primary Focus On Major/Minor P, Kyle Hallenbeck Jan 2008

Low Reynolds Number Water Flow Characteristics Through Rectangular Micro Diffusers/Nozzles With A Primary Focus On Major/Minor P, Kyle Hallenbeck

Electronic Theses and Dissertations

The field of microfluidics has recently been gathering a lot of attention due to the enormous demand for devices that work in the micro scale. The problem facing many researchers and designers is the uncertainty in using macro scaled theory, as it seems in some situations they are incorrect. The general idea of this work was to decide whether or not the flow through micro diffusers and nozzles follow the same trends seen in macro scale theory. Four testing wafers were fabricated using PDMS soft lithography including 38 diffuser/nozzle channels a piece. Each nozzle and diffuser consisted of a throat …

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Empirical Relationships Betweenload Test Data And Predicted Compression Capacity Of Augered Cast-In-Place Piles In Predominantly, Donald Mccarthy Jan 2008

Empirical Relationships Betweenload Test Data And Predicted Compression Capacity Of Augered Cast-In-Place Piles In Predominantly, Donald Mccarthy

Electronic Theses and Dissertations

Augered Cast-In-Place (ACIP) Piles are used in areas were the loading from a superstructure exceeds the soil bearing capacity for usage of a shallow foundation. In Northwest Florida and along the Gulf Coast, ACIP piles are often utilized as foundation alternatives for multi-story condominium projects. Data from 25 compression load tests at 13 different project sites in Florida and Alabama were analyzed to determine their individual relationships between anticipated and determined compression load capacity. The anticipated capacity of the ACIP pile is routinely overestimated due to uncertainties involved with the process of estimating the compressive capacity and procedures of placing …

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Efficient And Scalable Network Security Protocols Based On Lfsr Sequences, Saikat Chakrabarti Jan 2008

Efficient And Scalable Network Security Protocols Based On Lfsr Sequences, Saikat Chakrabarti

University of Kentucky Doctoral Dissertations

The gap between abstract, mathematics-oriented research in cryptography and the engineering approach of designing practical, network security protocols is widening. Network researchers experiment with well-known cryptographic protocols suitable for different network models. On the other hand, researchers inclined toward theory often design cryptographic schemes without considering the practical network constraints. The goal of this dissertation is to address problems in these two challenging areas: building bridges between practical network security protocols and theoretical cryptography. This dissertation presents techniques for building performance sensitive security protocols, using primitives from linear feedback register sequences (LFSR) sequences, for a variety of challenging networking applications. …

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