Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

University of Arkansas, Fayetteville

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 2731 - 2760 of 2828

Full-Text Articles in Engineering

Benefits Of Leed Designs In Arkansas K-12 Schools, Philip Thrift May 2008

Benefits Of Leed Designs In Arkansas K-12 Schools, Philip Thrift

Mechanical Engineering Undergraduate Honors Theses

This paper provides and evaluation of an existing LEED certified sustainable green building for energy-efficiency, environmental impact, economic value, and occupant health. The new Bethel Middle School located in Bryant, Arkansas was the first LEED (Leadership in Energy and Environmental Design) certified public school building in the state. Based on actual building specifications and validated with the first year's utility bills, a simulation model was used to evaluate various design aspects of the school building. The building's baseline energy usage was compared with numerous energy and environmental scenarios. Results include both environmental and economic assessments. Overall, the study found that …

Go to article

Development Of Low Temperature Alpha Alumina Coatings By Ac Magnetron Sputtering, Andrew Cloud May 2008

Development Of Low Temperature Alpha Alumina Coatings By Ac Magnetron Sputtering, Andrew Cloud

Mechanical Engineering Undergraduate Honors Theses

Alpha-phase aluminum oxide thin films were created using an Isoflux ICM-10 dual target inverted cylindrical magnetron sputtering system using mid-frequency AC power supplies. Alpha alumina films were deposited at a magnetron power of 6 kW, 50% oxygen partial pressure by volume, and -35 V DC bias. Film thickness, substrate material, and position and orientation within the deposition chamber were varied. To ensure the deposition conditions are suitable for alloys, the substrate temperature was measured using temperature indicating liquids. The experimental results, supported by Explicit Euler numerical analysis, revealed a steady state temperature of ~480°C at 6kW. Transmission electron microscopy (TEM) …

Go to article

Numerical Thermal-Fluid Analysis Of A Liquid Cooled Novel 3-D Electronic Package, Aron Meyer May 2008

Numerical Thermal-Fluid Analysis Of A Liquid Cooled Novel 3-D Electronic Package, Aron Meyer

Mechanical Engineering Undergraduate Honors Theses

The need for smaller and more powerful processors has become more and more important in recent times. This need is nowhere more evident than in the military where the ability to process large amounts of data quickly and accurately can save lives. So the University of Arkansas has been researching a new chip design, the 3-D stack-up thru-silicon via chip. This has several benefits over the traditional chip designs, but comes at the price of having more heat to be dissipated. Due to the need to dissipate up to 20 watts per wafer a liquid cooling system was used with …

Go to article

Computational Modeling Of Oxidative Stress: An Analysis Of Nad (P)H Effects On Nitric Oxide And Superoxide During Hypertension, Aaron Strobel May 2008

Computational Modeling Of Oxidative Stress: An Analysis Of Nad (P)H Effects On Nitric Oxide And Superoxide During Hypertension, Aaron Strobel

Biological and Agricultural Engineering Undergraduate Honors Theses

Nitric oxide (NO) is inactivated in the human body when exposed to superoxide (O2 -). This reaction forms peroxynitrite (ONOO-). Superoxide is produced in the cardiac system by several different ways, including NAD(P)H oxidase. Superoxide dismutase (SOD) breaks down superoxide into oxygen and hydrogen peroxide. This prevents superoxide from reacting with nitric oxide and allows normal function to take place. Superoxide and peroxynitrite are main contributors to vascular disease in the human body, in particular hypertension. Experiments have shown that there was an increase of superoxide production in spontaneously hypertensive rats (SHR) vs. age-matched Wistar Kyoto rats (WKY) that were …

Go to article

Aquatic Bacteria Removal Using Carbon Nanotubes, Suvish Melanta May 2008

Aquatic Bacteria Removal Using Carbon Nanotubes, Suvish Melanta

Biological and Agricultural Engineering Undergraduate Honors Theses

The purpose of this project is to explore the functionality of carbon nanotubes as a bacterial removal method, specifically towards water-borne bacterial pathogens in wastewater by utilizing its unique magnetic and bacteria-binding properties. The general protocol set for this research follows five steps: 1) Preparation of wastewater media, 2) preparation of CNT culture, 3) preparation of reaction mixture with CNTs for bacterial binding, 4) magnetic separation of bacteria-bound-CNT clusters and, 5) assessment of supernatant. The CNTs effectively removed bacterial contaminants in the wastewater (10%, v/v) after the sand filtration process from the Paul R. Noland Wastewater Facility at Fayetteville, Arkansas. …

Go to article

Factors Affecting The Spread Of A Bioterrorist Agent Throughout A Building, William A. Cantrell Jan 2008

Factors Affecting The Spread Of A Bioterrorist Agent Throughout A Building, William A. Cantrell

Inquiry: The University of Arkansas Undergraduate Research Journal

Bioterrorism has become a greater concern for Americans since the 2001 anthrax letters. Recent studies have explored the possibilities of biological attacks, and most deal with possible large-scale attacks. However, there is reason to believe that small-scale attacks are more likely. Even though there have been investigations of the postal delivery system and the spread of bioagents through mail, few if any studies have looked at attack on a single building and the resultant spread form room to room. One particular method of attacking a building would be a single-even release of an aerosol bioagent in the building. This paper …

Go to article

Computational Modeling Of Oxidative Stress: An Analysis Of Nad(P)H Effects On Nitric Oxide And Superoxide During Hypertension, Aaron Strobel Jan 2008

Computational Modeling Of Oxidative Stress: An Analysis Of Nad(P)H Effects On Nitric Oxide And Superoxide During Hypertension, Aaron Strobel

Inquiry: The University of Arkansas Undergraduate Research Journal

Nitric oxide (NO) is inactivated in the human body when exposed to superoxide (02-). This reaction forms peroxynitrite (ONOO). Superoxide is produced in the cardiac system by several mechanisms, including NAD(P)H oxidase. Superoxide dismutase (SOD) breaks down superoxide into oxygen and hydrogen peroxide. This prevents superoxide from reacting with nitric oxide and allows normal function to take place. Superoxide and peroxynitrite are main contributors to vascular disease in the human body, in particular hypertension.

Go to article

Improvement Of Prony's Method Of System Identification Vianonlinear Parameter Transformation, C. Wu Jan 2008

Improvement Of Prony's Method Of System Identification Vianonlinear Parameter Transformation, C. Wu

Journal of the Arkansas Academy of Science

This paper presents an approach to improve Prony’s method of identifying a linear time-invariant system. The method is based on a nonlinear transformation of parameters, which leads to data averaging. The method yields better results than a direct application of the least squares approach to Prony’s method. A numerical example is given to demonstrate the improvement attained by the new algorithm. Signals are assumed to be contaminated by zero-mean Gaussian white noise.

Go to article

Growth Rate Calculations For Epitaxially Grown Thin Films, D. Bullock Jan 2008

Growth Rate Calculations For Epitaxially Grown Thin Films, D. Bullock

Journal of the Arkansas Academy of Science

No abstract provided.

Go to article

Validation Of Adaptive Aeroelastic Finite Element Program For Two Dimensional Flow Past A Suspension Bridge Girder Section Using Unstructured Grids., Shanique Murray Dec 2007

Validation Of Adaptive Aeroelastic Finite Element Program For Two Dimensional Flow Past A Suspension Bridge Girder Section Using Unstructured Grids., Shanique Murray

Civil Engineering Undergraduate Honors Theses

The flow around suspension bridge decks was traditionally investigated using wind tunnel experiments. Computer modeling, an alternative to wind tunnel testing is now being used to simulate the wind flow around a bridge cross section. This alternative is less expensive and takes less time compared to wind tunnel experiments. The motion of flow around a bridge deck is described by a set of partial differential equations called Navier-Stokes (N-S) equations. Flow features such as velocity, pressure and vorticity are predicted by solving these equations. These flow features are then used to compute flow parameters such as aerodynamic drag, lift and …

Go to article

The Development Of Regional Regression Equations For Flood Flow Estimates Of Ungauged Streams In The State Of Arkansas, Stephen Mccall Dec 2007

The Development Of Regional Regression Equations For Flood Flow Estimates Of Ungauged Streams In The State Of Arkansas, Stephen Mccall

Civil Engineering Undergraduate Honors Theses

The objective of this project is to improve the accuracy of the peak streamflow frequency estimates in ungauged streams by using a regionalization approach and the Bulletin 17B method of flood flow analysis. The entire state will be considered one region and the final results will be compared to previous studies done in the state. The data used will be the most up-to-date available from the USGS gauging stations around the state. This includes data from gauging stations that had less than 10 years of data when the last such study was conducted by Hodge & Tasker (1995). The data …

Go to article

Conversion Of Biomass Resource To Useful Forms Of Energy And Other Products, Latosha Johnson Dec 2007

Conversion Of Biomass Resource To Useful Forms Of Energy And Other Products, Latosha Johnson

Chemical Engineering Undergraduate Honors Theses

The United States is facing increasing pressure to find renewable energy sources due to rising energy costs. With world energy demand at an all time high, renewable energy has been thrust into the forefront of research as a means to mitigate this looming crisis. Throughout the United States, there is a large quantity of agricultural biomass that could be used to generate energy and lessen the dependence on diminishing resources. Specifically, animal feeding operations (AFOs) such as dairies generate large amounts of cow manure, which, when improperly handled, causes both air and water pollution. Currently, most manure is temporarily stockpiled …

Go to article

Experimental Analysis Of Plasma Conditions In An Inverted Cylindrical Magnetron Sputtering System, Bradley Handloser Aug 2007

Experimental Analysis Of Plasma Conditions In An Inverted Cylindrical Magnetron Sputtering System, Bradley Handloser

Mechanical Engineering Undergraduate Honors Theses

In this report, we will investigate Langmuir probe and mass spectrometer plasma diagnostic systems used to characterize conditions within a magnetron sputtering system. The specific systems used were the ESPION Langmuir probe and EQP mass spectrometer by Hiden Analytical and the ICM-10 inverted cylindrical magnetron sputtering system by Isoflux, Inc. This paper will show how these systems work, are operated, and produce data. Low power oxygen and argon plasmas were used through this research for diagnostics. With the EQP, two modes were used to collect data: RGA for neutrals and radicals and SIMS for positive ions. With both modes, mass …

Go to article

Comparison Of Simulation-Based Schedule Generation Methodologies For Semiconductor Manufacturing, Wenfeng Li May 2007

Comparison Of Simulation-Based Schedule Generation Methodologies For Semiconductor Manufacturing, Wenfeng Li

Industrial Engineering Undergraduate Honors Theses

Although a number of approaches have been developed to schedule tasks or jobs in many different manufacturing environments, increasing manufacturing complexity continues to motivate the need for additional scheduling heuristic research and development. This is particularly true for semiconductor manufacturing operations, arguably the most complex manufacturing environment in existence. Simulation-based scheduling has shown recent promise as a means for developing schedules for dynamic, stochastic manufacturing environments. I investigate the potential advantages and drawbacks of using simulation-based scheduling in a complex job shop as motivated by a semiconductor wafer fab.

Go to article

Factors Affecting The Spread Of A Bioterrorist Agent Through A Building, William Cantrell May 2007

Factors Affecting The Spread Of A Bioterrorist Agent Through A Building, William Cantrell

Mechanical Engineering Undergraduate Honors Theses

Bioterrorism has become a concern for Americans since the 2001 anthrax letters. Many studies have been done regarding the possibilities of biological attacks since, and most deal with possibilities of large scale attacks. However, there is reason to believe that small scale attacks are more likely. Even though studies have been done revolving around the postal system and the spread of bioagents through mail, few if any studies have looked at an attack on a single building. One particular method of attacking a building would be simply releasing an aerosoled contaminant in the building. This purpose of this project is …

Go to article

A Study On The Application Of Thermoelectric Heat Pumps For Heating Applications, James Lincicome May 2007

A Study On The Application Of Thermoelectric Heat Pumps For Heating Applications, James Lincicome

Mechanical Engineering Undergraduate Honors Theses

Typically, thermoelectric heat pumps are used in cooling applications where space and portability are important, but they can be used efficiently in heating applications under the right conditions. This paper explains the origins of the thermoelectric heat pump, its applications in society, and the technical aspects of the device. The many different appurtenances that the device requires will be discussed along with their drawbacks. The single-stage data for the cells will be compared to the two-stage configuration data, and the data gathered for a specific thermoelectric device will be compared to the manufacturer's published data for the different configurations of …

Go to article

Atomic Force Microscope Imaging Of Dna And Multi Walled Carbon Nanotubes, Jacob Hohnbaum May 2007

Atomic Force Microscope Imaging Of Dna And Multi Walled Carbon Nanotubes, Jacob Hohnbaum

Mechanical Engineering Undergraduate Honors Theses

The Micro and Nano System Laboratory at the University of Arkansas currently is equipped with an Atomic Force Microscope (AFM). This device can be used to measure objects with resolution on the nanometer scale, but there are a number of technical difficulties in performing scans of carbon nanotubes and DNA. The goal of this research is to successfully perform scans on both carbon nanotubes and DNA and to also establish laboratory processing protocols to re-perform such scans in the future. Previous works performed by other researchers in the laboratory provided basic protocols with which to begin the present research. These …

Go to article

Design Of A Supersonic Wind Tunnel, Jay Pascual May 2007

Design Of A Supersonic Wind Tunnel, Jay Pascual

Mechanical Engineering Undergraduate Honors Theses

A supersonic wind tunnel was to be designed using the existing compressed air tank at the Mechanical Engineering building at the University of Arkansas. A throat area of 0.000375 m2 was used in the design process. The properties of the air were calculated using various Mach numbers. These results are used to determine if a wind tunnel of Mach numbers between one and five can be built at the University of Arkansas and can run for a sufficient amount of time. Also, the dimensions of the supersonic wind tunnel were calculated for these various Mach numbers.

Go to article

Improvement To The Data Logging Capability Of A Cough Monitoring System, Matthew Barlow Jan 2007

Improvement To The Data Logging Capability Of A Cough Monitoring System, Matthew Barlow

Inquiry: The University of Arkansas Undergraduate Research Journal

Data logging capability of a previously developed self contained cough recorder using an accelerometer as the sensing element is improved by using a secure digital memory card for later retrieval on a computer. Firmware is developed to enhance the functionality of the cough recorder. Existing libraries are modified for increased write rates. Increased writing speed allows 8-bit sampling at rates exceeding 8kHz, allowing for detailed time and frequency domain analysis. Additional features have also been developed to enable easy management of recordings, such as a file system compatibility with Microsoft Windows., and unique file names for each recording.

Go to article

Measurement And Modeling Of Light Transmission Through Turbid Media, Alois (Al) J. Adams, Michael Fahrenwald, Long Do Jan 2007

Measurement And Modeling Of Light Transmission Through Turbid Media, Alois (Al) J. Adams, Michael Fahrenwald, Long Do

Journal of the Arkansas Academy of Science

No abstract provided.

Go to article

Design Of Novel Experimental Techniques To Investigate The Formation Of Nanoparticle-Based Tribofilms, Corey Thompson Dec 2006

Design Of Novel Experimental Techniques To Investigate The Formation Of Nanoparticle-Based Tribofilms, Corey Thompson

Mechanical Engineering Undergraduate Honors Theses

Nano-engineered lubricant additives such as organically-active nanoparticles of molybdenum disulphide (Hybrid-milled MoS2) are becoming increasingly popular in the fight against harsh friction and wear that occurs during boundary-layer lubrication. A previous paper (Verma, 2007), has reported improvements in both coefficient of friction and wear scar diameter; however, there exists very little data concerning the methods through which this improvement is achieved. Using techniques such as atomic force microscopy (AFM), nanoindentation, scanning electron microscopy (SEM), focused ion beam (FIB), high resolution transmission electron microscopy (HRTEM) as well as tribometery, the chemical and mechanical characteristics of the nanoparticle based tribofilm are characterized. …

Go to article

Ultrafiltration Membrane Process For Pyrogen Removal In The Preparation Of Water For Injection (Wfi), Thet N. Soe Jan 2006

Ultrafiltration Membrane Process For Pyrogen Removal In The Preparation Of Water For Injection (Wfi), Thet N. Soe

Inquiry: The University of Arkansas Undergraduate Research Journal

An artificial kidney process based on ultrafiltration (called hemodiafiltration) more effectively removes blood toxins, particularly those of higher molecular weight, than conventional dialysis. In hemodiafiltration, replacement liquid must be added directly to the patient's blood to replace liquid filtered out of the blood in the ultrafiltration cartridge. This replacement liquid is made up of' "water for injection" (WFI) and other components such as salts and glucose. WFI is produced either by distillation or reverse osmosis and has a cost of $1.00 per liter. A patient with kidney problems would require three hemodiafiltration treatments per week, each requiring 70-80 liters of …

Go to article

Evaluation Of Rice Hulls As A Lignocellulosic Substitute In Wood Plastic Composites, P. Jack Bourne Jan 2006

Evaluation Of Rice Hulls As A Lignocellulosic Substitute In Wood Plastic Composites, P. Jack Bourne

Inquiry: The University of Arkansas Undergraduate Research Journal

Rising raw material costs and shortage of woody materials necessitate alternative sources for lignocellulosic material in wood plastic composites (WPC). This study was conducted to evaluate rice hull (RH), an agricultural residue, as a cellulosic substitute in WPC. Samples were fabricated with approximately 4% zinc stearate, 48% high-density polyethylene obtained from recycled plastics and 48% lignocellulosic material by mass. The composition of the lignocellulosic material was changed from 0 to 100% RH at 20% increments while the remainder was wood flour. The extruded sampled were tested for mechanical properties such as specific gravity, water absorption, linear coefficients of thermal expansion, …

Go to article

A Study Of The Impact Of Prognostic Errors On System Performance, Mauricio Carrasco Jan 2006

A Study Of The Impact Of Prognostic Errors On System Performance, Mauricio Carrasco

Inquiry: The University of Arkansas Undergraduate Research Journal

Condition-based maintenance is growing in popularity as a means of improving equipment maintenance efficiency. Whether it be the maintenance of an airplane, a computer system, or any type of physical system, the prognostic tools associated with condition-based maintenance are subject to statistical error. These errors can lead to unnecessary preventive maintenance due to underestimation of system remaining life and unnecessary system failures due to overestimation of system remaining life. What is not clear is if these statistical errors outweigh the benefits of a condition-based maintenance policy. This study attempts to address this concern through the evaluation and comparison of three …

Go to article

Use Of Calcium Hypochlorite As A Sanitizer For Seeds Used For Sprouting: Task #2; Impact: Improved Alfalfa Decontamination Technologies, Emily Damron, Carrie Klein, Melissa Leach, Jordan Mourot, Tom Murphy, Amy Seamans, Ryan Wilson Jan 2005

Use Of Calcium Hypochlorite As A Sanitizer For Seeds Used For Sprouting: Task #2; Impact: Improved Alfalfa Decontamination Technologies, Emily Damron, Carrie Klein, Melissa Leach, Jordan Mourot, Tom Murphy, Amy Seamans, Ryan Wilson

Inquiry: The University of Arkansas Undergraduate Research Journal

Consumption of raw or lightly cooked alfalfa sprouts has been a concern of the U.S. Food and Drug Administration (FDA) in recent years due to connections between sprouts and foodborne illnesses. Researchers have identified, contaminated seeds as the primary source of alfalfa sprouts contamination. Contamination of alfalfa seeds can originate in the field, harvesting, storing, or sprouting. Two pathogens of particular concern on alfalfa seeds are Escherichia coli 0157:H7 (E. coli) and Salmonella. These pathogens are capable of producing biofilms that provide protection for individual cells and allow for survival in otherwise hostile environments, including some disinfectant washes. Other factors …

Go to article

Parameter Extraction Software For Silicon Carbide Schottky, Merged Pin Schottky And Pin Power Diode Models, Edgar Cilio Jan 2004

Parameter Extraction Software For Silicon Carbide Schottky, Merged Pin Schottky And Pin Power Diode Models, Edgar Cilio

Inquiry: The University of Arkansas Undergraduate Research Journal

A software program for on-state parameter extraction is presented for the realization of a high quality model for SiC Schottky, Merged PiN Schottky, and PiN Power diodes based on McNutt and Mantooth's Comprehensive SiC Diode model [ 1 ].

Go to article

A Comparative Evaluation Of .Net Remoting And Java Rmi, Taneem Ibrahim Jan 2004

A Comparative Evaluation Of .Net Remoting And Java Rmi, Taneem Ibrahim

Inquiry: The University of Arkansas Undergraduate Research Journal

Distributed application technologies such as Micrososoft.NET Remoting, and Java Remote Method Invocation (RMI) have evolved over many years to keep up with the constantly increasing requirements of the enterprise. In the broadest sense, a distributed application is one in which the application processing is divided among two or more machines. Distributed middleware technologies have made significant progress over the last decade. Although Remoting and RMI are the two of most popular contemporary middleware technologies, little literature exists that compares them. In this paper, we study the issues involved in designing a distributed system using Java RMI and Microsoft.NET Remoting. In …

Go to article

Investigation On How To Improve Latent Semantic Analysis Performance, Thao Doan Jan 2003

Investigation On How To Improve Latent Semantic Analysis Performance, Thao Doan

Inquiry: The University of Arkansas Undergraduate Research Journal

Latent Semantic Analysis (LSA) is a matching technique capable of recognizing the semantic relationships of data that ordinary techniques such as string matching cannot. This is especially valuable for data integration applications, like those of Acxiom, where data items are usually related by context, rather than in a literal match. Even though it has been shown that LSA is 30% more effective in finding and ranking relevant pieces of information than existing string-by-string matching techniques (Deerwester et al., 1990; Dumais, 1995), the performance of the LSA seems to be affected by the presence of shared words, or “noise”, in data. …

Go to article

Computer Modeling Of Tornado Forces On A Cubic Building Using Large Eddy Simulation, R. Panneer Selvam, Paul C. Millett Jan 2003

Computer Modeling Of Tornado Forces On A Cubic Building Using Large Eddy Simulation, R. Panneer Selvam, Paul C. Millett

Journal of the Arkansas Academy of Science

A tornado changes its wind speed and direction rapidly; therefore, it is difficult to study the effects of a tornado on buildings in a wind tunnel. The status of the tornado-structure interaction and various models of the tornado wind field found in literature are surveyed. Three dimensional computer modeling work using the turbulence model based on large eddy simulation is presented. The effect of a tornado on a cubic building is considered for this study. The Navier-Stokes (NS) equations are approximated by the finite difference method and solved by an implicit procedure. The force coefficients are plotted in time to …

Go to article

Interpolation Techniques For Overset Grids, Paul S. Sherman, Nathan B. Edgar Jan 2003

Interpolation Techniques For Overset Grids, Paul S. Sherman, Nathan B. Edgar

Journal of the Arkansas Academy of Science

The use of finite difference schemes in computational aeroacoustics requires the use of structured grids incomputational space. Complex geometries in the physical space can be modeled using multiple overlapping grids that are transformed into computational space. In this work, finite difference schemes are used that necessitate the addition of psuedo- or ghost-points in the overlap region of the grids for closure of the difference stencil. The functional values at these ghost points must be approximated from the values at the original grid points. This paper investigates interpolation techniques for these overset grids. An n th order interpolation scheme using Lagrange …

Go to article

First Prev Next Last