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University of Arkansas, Fayetteville

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Articles 1651 - 1680 of 2433

Full-Text Articles in Physical Sciences and Mathematics

Modeling Of Compositionally Graded Barium Strontium Titanate From First Principles, Laura Elizabeth Walizer May 2009

Modeling Of Compositionally Graded Barium Strontium Titanate From First Principles, Laura Elizabeth Walizer

Graduate Theses and Dissertations

"Barium Strontium Titanate (BaxSr1-xTiO3 or BST) is a Perovskite alloy of interest for both technological and intellectual reasons. Its ferroelectric and piezoelectric properties make it useful in a variety of electric components such as transducers and actuators, and BST in particular is a material of interest for the development of a ferroelectric RAM for computers. The inclusion of SrTiO3, an incipient ferroelectric, and the fact that the properties of a BST system depend strongly on its relative composition of BaTiO3 and SrTiO3 (ST), make also this a material of high interest. Compositionally graded systems are of further interest , partly …

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Wayne E. Sabbe Arkansas Soil Fertility Studies 2008, Nathan A. Slaton Mar 2009

Wayne E. Sabbe Arkansas Soil Fertility Studies 2008, Nathan A. Slaton

Arkansas Agricultural Experiment Station Research Series

Rapid technological changes in crop management and production require that the research efforts also be presented in an expeditious manner. The contributions of soil fertility and fertilizers are major production factors in all Arkansas crops. The studies described within will allow producers to compare their practices with the university’s research efforts.

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Carbon Nanotube Cluster Based Micro-Fluidic System For Bacteria Capture, Concentration, And Separation, Chris Nelson Jan 2009

Carbon Nanotube Cluster Based Micro-Fluidic System For Bacteria Capture, Concentration, And Separation, Chris Nelson

Inquiry: The University of Arkansas Undergraduate Research Journal

Disease-causing pathogens continue presenting enormous global health problems, especially due to their easy transmittance to people via water supply systems. The detection, filtration, and purification of bacteria-contaminated water samples are complex activities, ones subject to considerable error. Here we present a new and highly effective micro-fluidic system with carbon nanotube (CNT) clusters for effective and efficient detection, filtration, and purification of bacteria-contaminated medium. The developed system is based upon two unique properties of CNT clusters: high bacterial affinity and magnetic susceptibility. The CNTs 'high affinity to bacteria cells makes them a key candidate for the bacteria adsorption. The magnetic susceptibility …

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Economic Impacts Of Future Biorefineries In The State Of Arkansas: An Input-Output Analysis, Sayeed R. Mehmood, M. H. Pelkki Jan 2009

Economic Impacts Of Future Biorefineries In The State Of Arkansas: An Input-Output Analysis, Sayeed R. Mehmood, M. H. Pelkki

Journal of the Arkansas Academy of Science

No abstract provided.

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Development Of A Distributed Artificial Neural Network For Hydrologic Modeling, Rebecca Logsdon Jan 2009

Development Of A Distributed Artificial Neural Network For Hydrologic Modeling, Rebecca Logsdon

Inquiry: The University of Arkansas Undergraduate Research Journal

Hydrological models are used to represent the rainfall-runoff and pollutant transport mechanisms within watersheds. Accurate representation of these dynamic and complex natural processes within a watershed is an important step in managing and protecting a watershed Artificial neural network (ANN) models are often used in hydrologic modeling. Typical ANN models are trained to use lumped data. However, watershed characteristics used as inputs in hydrological modeling are spatially and often temporally dynamic. Therefore, a lumped model does not have the ability to represent changes in spatial dynamics of a watershed. Therefore, the purpose of this study was to develop and test …

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Microwave Synthesis Of Cis-Dichlorotetrakis(Dimethylsulfoxide)Ruthenium(Ii), A. Harvey, Mark Draganjac, S. Chui, R. Snell, E. Benjamin Jan 2009

Microwave Synthesis Of Cis-Dichlorotetrakis(Dimethylsulfoxide)Ruthenium(Ii), A. Harvey, Mark Draganjac, S. Chui, R. Snell, E. Benjamin

Journal of the Arkansas Academy of Science

No abstract provided.

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The Beauty Of Mathematics And The Mathematics Of Beauty: Continued Fractions And The Golden Ratio, Jessica Tush Jan 2009

The Beauty Of Mathematics And The Mathematics Of Beauty: Continued Fractions And The Golden Ratio, Jessica Tush

Inquiry: The University of Arkansas Undergraduate Research Journal

This project begins with a look at the history of simple continued fractions and how we have arrived where we are today. We then move through a study of simple continued fractions, beginning first with rational numbers and moving to irrational numbers. Continuing further in the pursuit of joining mathematics and art, we define the specific continued fraction that gives rise to the Fibonacci sequence and the Golden Ratio~ (phi, pronounced 'Jai"). These two notions form a direct link to art and the properties that we hope to examine. I have taken an analytic approach to showing that the Golden …

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E-85 Vs. Regular Gasoline: Effects On Engine Performance, Fuel Efficiency, And Exhaust Emissions, Jordan W. Steinhaus, Donald M. Johnson, George W. Wardlow Jan 2009

E-85 Vs. Regular Gasoline: Effects On Engine Performance, Fuel Efficiency, And Exhaust Emissions, Jordan W. Steinhaus, Donald M. Johnson, George W. Wardlow

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

This study compared the performance, fuel efficiency, and exhaust emissions of a 2.61 kW engine fueled with regular unleaded gasoline (87 octane) and an 85% ethanol blend (E85) under two load conditions. Four 1-h tests were conducted with each fuel at both governor’s maximum (3400 rpm) and peak torque (2800 rpm) conditions for a total of 16 tests. At governor’s maximum engine speed, there were no significant differences (p>0.05) between fuels for engine torque, power, specific carbon dioxide (sCO2 ), specific carbon monoxide (sCO), specific hydrocarbons (sHC), or specific oxides of nitrogen (sNOX) emissions. However, there was a significant …

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Synthesis And Characterization Of Homoleptic And Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan, S. Kudo, C. Wade, R. F. Davis Jan 2009

Synthesis And Characterization Of Homoleptic And Heteroleptic Ruthenium Polypyridine Complexes, Anwar A. Bhuiyan, S. Kudo, C. Wade, R. F. Davis

Journal of the Arkansas Academy of Science

The homoleptic ruthenium(II) complex Ru(C13H10N2)3(PF6)2, and heteroleptic ruthenium(II) complexes Ru(C13H10N2)2(C10H8N2)(PF6)2, and Ru(C13H10N2)(C10H8N2)2(PF6)2 have been prepared by following the standard synthetic procedure. These complexes were then purified by repeated column chromatography. The identity and the integrity of the complexes were confirmed by elemental analysis and mass spectroscopy. The calculated and the experimental values for the elemental analysis were in good agreement. The calculated and the experimental molar masses obtained were also identical. Ultravioletvisible absorption and emission spectroscopic methods were used to investigate the properties of these complexes. The absorption spectra of all complexes consist of a series of absorption bands in …

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Biological And Economic Considerations In Establishing A Short-Rotation Bioenergy Plantation, Jamie L. Schuler, M. Pelkki, Chris Stuhlinger Jan 2009

Biological And Economic Considerations In Establishing A Short-Rotation Bioenergy Plantation, Jamie L. Schuler, M. Pelkki, Chris Stuhlinger

Journal of the Arkansas Academy of Science

The development of bio-fuel synthesis technologies has led to increased interest in woody crops grown specifically for energy production. These woody feedstocks typically involve fast-growing species (e.g., Salix spp., Populus spp.) planted at high densities using short rotations and intensive cultural practices like weed control and fertilization. Under ideal conditions, this type of system can produce 20 dry Mg/ha/yr, which is substantially higher than the 2.5-4 dry Mg/ha/yr produced by pine plantations in the southern U.S. Many of these plantings are projected to be established on lower quality agricultural lands. Recent attempts at establishing these plantations have highlighted some of …

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Microwave Syntheses And Thermal Gravimetric Analysis Of Trans-Hydrogen Bis(Dimethylsulfoxide)Tetrachlororuthenate(Iii), S. Chui, Mark Draganjac, E. Benjamin, B. Rougaeu Jan 2009

Microwave Syntheses And Thermal Gravimetric Analysis Of Trans-Hydrogen Bis(Dimethylsulfoxide)Tetrachlororuthenate(Iii), S. Chui, Mark Draganjac, E. Benjamin, B. Rougaeu

Journal of the Arkansas Academy of Science

No abstract provided.

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Dna Sequence Analysis Of Freshwater Eustigmatophyceae, A Potential Source Of Essential Fatty Acids, Sara E. Prior, M. W. Fawley, K. P. Fawley Jan 2009

Dna Sequence Analysis Of Freshwater Eustigmatophyceae, A Potential Source Of Essential Fatty Acids, Sara E. Prior, M. W. Fawley, K. P. Fawley

Journal of the Arkansas Academy of Science

Freshwater Eustigmatophyceae are a group of microalgae that are considered rare and of low diversity, with only a few genera and species in a single order. Some Eustigmatophyceae produce fatty acids that are important nutrients for aquaculture, as well as for human food consumption. In addition, some Eustigmatophyceae produce hydrocarbons that may be useful in biofuel production. In our studies of the diversity of coccoid algae from Itasca State Park, Minnesota, we discovered several isolates that we tentatively identified as Eustigmatophyceae. Preliminary molecular characterization indicated that these isolates were highly diverse and probably represented species new to science. In this …

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New Eclipsing Close Binary Star In The Constellation Of Sextants, Jeff W. Robertson Jan 2009

New Eclipsing Close Binary Star In The Constellation Of Sextants, Jeff W. Robertson

Journal of the Arkansas Academy of Science

No abstract provided.

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Measurement Of Transient Smoke Emissions From Diesel And Biodiesel Fuel Blends In An Agricultural Tractor, Kristin M. Pennington, Sonia R. Munoz, Donald M. Johnson, George Wardlow Jan 2009

Measurement Of Transient Smoke Emissions From Diesel And Biodiesel Fuel Blends In An Agricultural Tractor, Kristin M. Pennington, Sonia R. Munoz, Donald M. Johnson, George Wardlow

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Transient smoke emissions pose potential hazards to human health and the environment. With the increased popularity of biodiesel, there is a need to determine if these fuels produce different levels of particulate matter in exhaust emissions. This study examined the transient smoke emissions of three fuels: No. 2 petroleum diesel fuel (D2, ASTM D 975), a blend of 20% biodiesel and 80% petroleum diesel (B20, ASTM 6751), and a 100% pure biodiesel derived from animal fats (B100, ASTM D 6751). Measurements of smoke emissions were taken using the SAE J1677 snap acceleration test procedure on a John Deere 3203 compact …

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Steganography In Ipv6, Barret Miller Dec 2008

Steganography In Ipv6, Barret Miller

Computer Science and Computer Engineering Undergraduate Honors Theses

Steganography is the process of hiding a secret message within another message such that it is difficult to detect the presence of the secret message. In other words, the existence of the secret message is hidden. A covert channel refers to the actual medium that is used to communicate the information such as a message, image, or file. This honors thesis uses steganography within the source address fields of Internet Protocol Version 6 (IPv6) packets to create a covert channel through which clandestine messages are passed from one party to another. A fully functional computer program was designed and written …

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Mapping Reality Into Virtual Worlds, Josh Mcfarlane Dec 2008

Mapping Reality Into Virtual Worlds, Josh Mcfarlane

Computer Science and Computer Engineering Undergraduate Honors Theses

As virtual worlds become more prevalent, they become increasingly useful as a means of information dissemination. This thesis examines the possible connections between real world objects and their virtual world counterparts. We look at how, by attaching sensors to an object, or by using a smart object with embedded sensors, the information can be relayed to a server. From this information, it will be possible to create a duplicate object in the virtual world and have it mirror the real world object in terms of state and movement. Almost all current solutions for remotely viewing a room or area are …

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Service Oriented Transitive Closure Solution, Jonathan Baran Aug 2008

Service Oriented Transitive Closure Solution, Jonathan Baran

Computer Science and Computer Engineering Undergraduate Honors Theses

The goal of this project is a service based solution that utilizes parallel and distributed processing algorithms to solve the transitive closure problem for a large dataset. A dataset may be view conceptually as a table in a database, with a physical structure representing a file containing a sequence of records and fields. Two records are said to be transitively related if and only if they are directly related due to sharing of one or more specific fields, or a sequence may be made from one record to the other under the condition that all intermediate entries are related the …

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Location-Based Hashing For Querying And Searching, Felix Ching May 2008

Location-Based Hashing For Querying And Searching, Felix Ching

Computer Science and Computer Engineering Undergraduate Honors Theses

The rapidly growing information technology in modern days demands an efficient searching scheme to search for desired data. Locality Sensitive Hashing (LSH) is a method for searching similar data in a database. LSH achieves high accuracy and precision for locating desired data, but consumes a significant amount of memory and time. Based on LSH, this thesis presents two novel schemes for efficient and accurate data searching: Locality Sensitive Hashing-SmithWaterman (LSH-SmithWaterman) and Secure Min-wise Locality Sensitive Hashing (SMLSH). Both methods dramatically reduce the memory and time consumption and exhibit high accuracy in data searching. Simulation results demonstrate the efficiency of the …

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An Efficient Hardware Implementation Of Target Recognition Algorithms And Investigation Of Secure Wireless Communication For A Modified Manet, Stephen Barnes May 2008

An Efficient Hardware Implementation Of Target Recognition Algorithms And Investigation Of Secure Wireless Communication For A Modified Manet, Stephen Barnes

Computer Science and Computer Engineering Undergraduate Honors Theses

This paper presents a scheme for effective wireless security of a open broadcast mobile ad-hoc network, MANET, network without significant loss of bandwidth and data integrity through a double tiered encryption scheme, and the feasibility of reducing the target tracking algorithm in [1] into a compact and efficient hardware package. Due to the open nature of MANET, modifications are necessary to secure wireless data in a potential hostile environment. Furthermore, due to power and processing limitations of small unmanned aerial vehicles (UAVs) and the processing intensive calculations of image processing, a sample hardware implementation of key functions of the target …

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A Timer Module For An 8051 Microcontroller, Troy England May 2008

A Timer Module For An 8051 Microcontroller, Troy England

Electrical Engineering Undergraduate Honors Theses

A timer module for an 8051 Microcontroller is designed from the ground up. It could potentially be integrated into a larger 8051 for use in lunar and Martian missions. It follows through a synchronous digital design flow from HDL code through layout verification. The timer shows functionality at 100MHz with some minor glitches.

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Computer Generation And Processing Of Music: Pitch Correction For The Human Voice, Jason Hardy May 2008

Computer Generation And Processing Of Music: Pitch Correction For The Human Voice, Jason Hardy

Computer Science and Computer Engineering Undergraduate Honors Theses

No abstract provided.

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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. …

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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 …

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Developing Subgrade Inputs For Mechanistic-Empirical Pavement Design, Meagan Berlau May 2008

Developing Subgrade Inputs For Mechanistic-Empirical Pavement Design, Meagan Berlau

Computer Science and Computer Engineering Undergraduate Honors Theses

No abstract provided.

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Holistic Characterization Of Parallel Programming Models In A Distributed Memory Environment, Christopher Bryan May 2008

Holistic Characterization Of Parallel Programming Models In A Distributed Memory Environment, Christopher Bryan

Computer Science and Computer Engineering Undergraduate Honors Theses

The popularity of cluster computing has increased focus on usability, especially in the area of programmability. Languages and libraries that require explicit message passing have been the standard. New languages, designed for cluster computing, are coming to the forefront as a way to simplify parallel programming. Titanium and Fortress are examples of this new class of programming paradigms. This work holistically characterizes these languages and contrasts them with the standard model of parallel programming, and presents benchmark results of small computational kernels written in these languages and models.

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Multiuav2 Agent Swarming For Distributed Atr Simulation, Kyle White May 2008

Multiuav2 Agent Swarming For Distributed Atr Simulation, Kyle White

Computer Science and Computer Engineering Undergraduate Honors Theses

Traditional automatic target recognition (ATR) is performed by unmanned aerial vehicles (UAVs) depending on a central control tower to provide the high level organization of the system. The UAVs fly through a region of interest to identify targets and relay all communication through a central control tower. The centralized approach to ATR has limited fault-tolerance, scalability with regards to the number of UAVs, and susceptibility to malicious attacks on the central tower [2]. A swarm-driven alternative [1] is extended with a communication control scheme to address fault-tolerance and scalability while utilizing the higher onboard processing power now available for UAVs …

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Visualization Of An Approach To Data Clustering, Marisabel Guevara May 2008

Visualization Of An Approach To Data Clustering, Marisabel Guevara

Computer Science and Computer Engineering Undergraduate Honors Theses

Using visualization and clustering goals as guidelines, this thesis explores a graphic implementation of a data clustering technique that repositions vertices by applying physical laws of charges and springs to the components of the graph. The resulting visualizations are evidence of the success of the approach as well as of the data sets that lend themselves to a clustering routine. Due to the visual product of the implementation, the algorithm is most useful as an aid in understanding the grouping pattern of a data set. Either for a rapid analysis or to assist in presentation, the visual result of the …

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Adding Virtual Rfid To Second Life, Casey Bailey May 2008

Adding Virtual Rfid To Second Life, Casey Bailey

Computer Science and Computer Engineering Undergraduate Honors Theses

Second Life (SL) is a popular online 3D multi-player virtual world where the limits of creating objects and scripting interactions among objects and avatars are based on the player's imagination and scripting skill. Real life, by comparison, is often limited by current technology more than creativity. This thesis investigates a new way to merge reality and virtual reality, in particular, by modeling one emerging real world technology, radio frequency identification (RFID), in the SL virtual world. We investigate how RFID can be deployed and tested in a virtual world, a modeled healthcare facility, as a step before the much more …

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Pitch Correction On The Human Voice, Suzanne Ownbey May 2008

Pitch Correction On The Human Voice, Suzanne Ownbey

Computer Science and Computer Engineering Undergraduate Honors Theses

No abstract provided.

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Wayne E. Sabbe Arkansas Soil Fertility Studies 2007, Nathan A. Slaton Apr 2008

Wayne E. Sabbe Arkansas Soil Fertility Studies 2007, Nathan A. Slaton

Arkansas Agricultural Experiment Station Research Series

Rapid technological changes in crop management and production require that the research efforts also be presented in an expeditious manner. The contributions of soil fertility and fertilizers are major production factors in all Arkansas crops. The studies described within will allow producers to compare their practices with the university’s research efforts. Additionally, soil test data and fertilizer sales are presented to allow comparisons among years, crops, and other areas within Arkansas.

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