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

Physical Sciences and Mathematics Commons™

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

Other

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type

Articles 1981 - 2010 of 2111

Full-Text Articles in Physical Sciences and Mathematics

Synthesis And Characterization Of Magnetic Nanoparticles, Narayan Poudyal Aug 2005

Synthesis And Characterization Of Magnetic Nanoparticles, Narayan Poudyal

Physics Theses - Archive

Synthesis of uniform nanoparticles (<100 nm) of hard and soft magnetic materials have attracted much attention in the last two decades because of their unique magnetic properties and potential for many applications such as high density recording media, biotechnology, ferrofluids, and fabrication of exchange-coupled nanocomposite permanent magnets. In this thesis, synthesis and characterization of hard (FePt) and soft (Fe3O4 and CoFe2O4) magnetic nanoparticles with different sizes are reported. Monodisperse FePt, Fe3O4 and CoFe2O4 nanoparticles were synthesized by chemical solution methods. Particle diameter was tuned from 3 to 20 nm by varying reaction conditions or by seed-mediated growth method. Monodisperse face-centered tetragonal (fct) FePt nanoparticles were prepared by annealing at 700oC the disodered face-centered cubic (fcc) FePt nanopaticles in NaCl matrix to convert the fcc particles into ordered fct structure. Morphological, structural, and compositional characterizations of the nanoparticles were performed by Transmission Electron Microscopy (TEM), High resolution TEM (HRTEM), Laser Particle-Size Analyzer, X-ray Diffractometer (XRD), Energy Dispersive X-ray (EDX), and Inductively Coupled Plasma (ICP). Magnetic properties of nanoparticles of different sizes at different temperatures were studied by Anternating Gradiant Magnetometer (AGM), and Superconducting Quantum Interference Device (SQUID) magnetometer. It has been found that all the as-synthesized Fe3O4 nanoparticles up to 20 nm are superparamagnetic at room temperatue while CoFe2O4 nanoparticles larger than 12 nm are ferromagnetic. An exchange bias field up to 3 kOe was observed for 3 nm CoFe2O4 nanoparticles in field cooling measurements. Very high coercivity of the isolated fct FePt nanoparticles up to 30 kOe at room temperature has been obtained. Interesting experimental results on the size dependent magnetic properties for both the hard and soft magnetic nanoparticles at different temperatures have been found.

Go to article

A First-Principles Study On The Enhancement Of Beryllium Doping In Gallium Nitride, Xiao Wang Aug 2005

A First-Principles Study On The Enhancement Of Beryllium Doping In Gallium Nitride, Xiao Wang

Physics Theses - Archive

The excellent physical and electrical properties of Gallium Nitride (GaN) have made it a good candidate in light-emitting diodes and UV detecting semiconductor materials. However, GaN's p-type doping has long been a difficulty. Although beryllium (Be) substitutials arise as shallow acceptors in GaN, the concentration of Be substitutials, and hence the population of holes, is not high enough. In the present work, formation energies of Be point defects and complex defects are calculated and compared by first-principles density functional theory (DFT) method. We find self-compensation is easily formed when Be substitutials and Be interstitials co-exist in GaN, which is responsible …

Go to article

On The Behavior Of The 5f Electrons, Pratik Pankajkumar Dholabhai Aug 2005

On The Behavior Of The 5f Electrons, Pratik Pankajkumar Dholabhai

Physics Theses - Archive

Considerable theoretical efforts have been devoted in recent years to studying the electronic and geometric structures and related properties of surfaces to high accuracy. One of the many motivations for this burgeoning effort has been a desire to understand the detailed mechanisms that lead to surface corrosion in the presence of environmental gases; a problem that is not only scientifically and technologically challenging but also environmentally important. Such efforts are particularly important for systems like the actinides for which experimental work is relatively difficult to perform due to material problems and toxicity. As is known, the actinides are characterized by …

Go to article

Finding Blood In Capsule Endoscopy Video, Jay Frederick Cox Aug 2005

Finding Blood In Capsule Endoscopy Video, Jay Frederick Cox

Computer Science and Engineering Theses - Archive

Capsule Endoscopy (CE) is a new procedure where endoscopists can visualize and discriminate anomalies of the human gastrointestinal track by allowing the patient to swallow a camera pill. The digital video obtained from the pill is used to safely pinpoint the location of these abnormalities in areas previously unavailable for view. One of the main functions of CE is determining the location of bleeding. Given Imaging, currently the only maker of a FDA approved CE device, has a proprietary and unspecified blood test, called Suspected Blood Index, which can be used to automatically detect where blood occurs in the video. …

Go to article

An Emperical Evaluation Of Adequacy Criteria For Testing Concurrent Programs, Gaurav Saini Aug 2005

An Emperical Evaluation Of Adequacy Criteria For Testing Concurrent Programs, Gaurav Saini

Computer Science and Engineering Theses - Archive

A concurrent program contains two or more threads that execute concurrently and work together to perform some task. Concurrency increases the efficiency of a program. Testing of concurrent programs has been a challenging task because of the inherent non-determinism. Most approaches proposed for concurrent program testing employ, explicitly or implicitly, a coverage criterion to measure test adequacy. In order to apply those approaches, we must first choose a criterion that suits best for our programs. There is a need for quantitative results of evaluation regarding the effectiveness of the various coverage criteria used for the testing of concurrent programs. Such …

Go to article

Comparison Of Search-Based And Kernel-Based Methods For Graph-Based Relational Learning, Chris Manuel Gonsalves Aug 2005

Comparison Of Search-Based And Kernel-Based Methods For Graph-Based Relational Learning, Chris Manuel Gonsalves

Computer Science and Engineering Theses - Archive

Graph-based relational learning has been the focus of relational learning for quite some time. As most of the real-world data is structured, and hence cannot be represented in a single table, various logic-based and graph-based techniques have been proposed for dealing with structured data. Our goal is to perform an in-depth analysis of two such graph-based learning systems. We have selected Subdue to represent the search-based approach and support vector machine (SVM) with graph kernels to represent the kernel-based approach. We perform a comparison between search-based and kernel-based approaches and evaluate their performance in various domains. A search-based approach to …

Go to article

A Framework For A Dynamic Invocation Interface And High-Level Interoperability For Mobile Agent Platforms, Vamsi K. Putrevu Aug 2005

A Framework For A Dynamic Invocation Interface And High-Level Interoperability For Mobile Agent Platforms, Vamsi K. Putrevu

Computer Science and Engineering Theses - Archive

The mobile agent paradigm for distributed systems is inherently suitable for many applications ranging from network management to e-commerce. One inherent problem to its wide spread use is communication between disparate agent platforms and reducing overheads while doing the same. Not all platforms for mobile agents are the same. The Mobile Agent Facility (MAF) proposal is an attempt to standardize this execution environment, this thesis proposes a framework extending the current MAF specification, by which inter-agent communication can be achieved in a more scalable fashion by interpreter based mobile agent systems. The future of the Internet depends on its ability …

Go to article

Monitoring And Analyzing Distributed Cluster Performance And Statistics Of Atlas Job Flow, Sreeranjani Ramprakash Aug 2005

Monitoring And Analyzing Distributed Cluster Performance And Statistics Of Atlas Job Flow, Sreeranjani Ramprakash

Computer Science and Engineering Theses - Archive

Grid3 is a Grid facility used by many High Energy Physics experiments to enable physicists to process data intensive and CPU intensive jobs more effectively as well as more efficiently. Amongst other things, the highlights of Grid3 are participation by more than 25 sites across the U.S. and Korea which collectively provide more than 2000 CPU's, resources used by seven different scientific applications, including three high energy physics simulations and four data analyses in high energy physics, bio-chemistry, astrophysics and astronomy, more than 100 individuals are currently registered with access to the Grid, a peak throughput of 500-900 jobs running …

Go to article

Sql-Based Approach To Significant Interval Discovery In Time-Series Data, Sunit Shrestha Aug 2005

Sql-Based Approach To Significant Interval Discovery In Time-Series Data, Sunit Shrestha

Computer Science and Engineering Theses - Archive

With time-series data, events (like turning off a light, opening garage door, turning on TV) occur with a high degree of certainty not at specific time points but within time intervals (sequence of time points). So, it is useful for applications to consider data as contiguous time points. The smallest interval that satisfies the criteria of interval-confidence (i.e., ratio of total support of participating time points and the number of days) is termed as Significant Interval (SI). Significant Interval Discovery (SID) algorithm finds SIs from time-series data. The main focus of this thesis is on the improvement of existing SID …

Go to article

Quantitative Comparison Of Two Approaches To Agent Cooperation, Jose Ramon Espino Aug 2005

Quantitative Comparison Of Two Approaches To Agent Cooperation, Jose Ramon Espino

Computer Science and Engineering Theses - Archive

Multi-agent systems (MASs) are characterized by collections of autonomous agents that interact with each other in simple ways, but the collection of agents as a whole is characterized by emergent behavior (EB) which will have properties that individual agents do not. Engineers want to design artificial MASs for a variety of reasons including military operations. The idea is for the EB to be carrying out the mission itself. In this scenario, the agents are relatively inexpensive and expendable. A large body of work exists in MAS research for military applications and a variety of different designs have been proposed. Because …

Go to article

Utility Based Resource Aware Framework For Information Caching And Sharing In Mobile And Distributed Systems, Huaping Shen Aug 2005

Utility Based Resource Aware Framework For Information Caching And Sharing In Mobile And Distributed Systems, Huaping Shen

Computer Science and Engineering Dissertations - Archive

Along with the technology advancements in mobile and wireless networks, ubiquitous information service is becoming a reality in which users can access the information anytime anywhere. However, the user mobility, network heterogeneity and resource constraints impose significant challenges to provide ubiquitous information services. In this dissertation, a utility based resource aware framework is proposed to enhance ubiquitous information availability to mobile users through data caching and peer-to-peer sharing. The framework considers the constrained resources of mobile and distributed environments and provides flexible, efficient and scalable data access services to the mobile users. The major contributions of this framework are as …

Go to article

Efficient And Adaptive Schemes For Consistent Information Sharing In Wireless Mobile And Peer-To-Peer Networks, Zhijun Wang Aug 2005

Efficient And Adaptive Schemes For Consistent Information Sharing In Wireless Mobile And Peer-To-Peer Networks, Zhijun Wang

Computer Science and Engineering Dissertations - Archive

With the tremendous growth of applications in wireless mobile and Peer-to-Peer (P2P) networks, significant research efforts have been made to improve the quality of sevice. Caching and replicating frequently used data objects or files in user's local buffers are popular mechanisms to effectively reduce the communication bandwidth requirement and thus improve the overall system performance. However, the frequent disconnections of users make data consistency a difficult task in wireless mobile and P2P networks. In this dissertation, we design and analyze a Scalable Asynchronous Cache Consistency Scheme (SACCS) for single cell wireless cellular networks. SACCS is a highly scalable, efficient, and …

Go to article

Game Theoretical Models And Algorithms For Rate Control In Video Compression, Jiancong Luo Jul 2005

Game Theoretical Models And Algorithms For Rate Control In Video Compression, Jiancong Luo

Computer Science and Engineering Dissertations - Archive

This thesis investigates game theory based rate control algorithms for optimizing the bit allocation in video compression. The first algorithm utilizes the cooperative bargaining game in a MB level rate control algorithm to optimize the perceptual quality while guaranteeing "fairness" in bit allocation among macroblocks. The algorithm first allocates the target bits to frames based on their coding complexity; a method to estimate the coding complexity of the remaining frames is proposed. Next, macroblocks of a frame play cooperative games such that each macroblock competes for a share of resources (bits) to optimize its quantization scale while considering the human …

Go to article

Group Key Distribution Via Local Collaboration In Wireless Sensor Networks, Anuj Chadha Jul 2005

Group Key Distribution Via Local Collaboration In Wireless Sensor Networks, Anuj Chadha

Computer Science and Engineering Theses - Archive

Wireless sensor networks have been recognized as one of the most important technologies in the networking world. Security of sensor networks is one of the major concerns today. To this end, a whole suite of protocols have been designed to provide various security features which includes key management. This thesis covers the issue of group key management in wireless sensor networks. Traditional cryptographic techniques can be used to provide communication privacy and integrity, but do not provide scalable solutions to group key management. A group key management scheme for sensor networks has been discussed that targets at fast response to …

Go to article

Distributed Streaming For Video On Demand, Shraddha Rumade Jul 2005

Distributed Streaming For Video On Demand, Shraddha Rumade

Computer Science and Engineering Theses - Archive

With the advent of digital media, implementing reliable Video on Demand (VoD) systems over the best effort Internet is a potential issue. Distributed streaming for Video on Demand presents a combination of two techniques. The first being Distributed Video Streaming using Multicast (DVSM) [1] involves video streaming from multiple servers to overcome path congestion. The second technique, Asynchronous Hybrid mechanism for Video on Demand [2] implements segmentation-based periodic broadcast to effectively share network bandwidth. In this work we aim at providing path diversity of multiple senders and maximizing bandwidth sharing via multicast. We exploit alternate paths in case of congestion …

Go to article

Statistical Analysis Of Rock Fabrics, Boris Avdeev Jul 2005

Statistical Analysis Of Rock Fabrics, Boris Avdeev

Earth & Environmental Sciences Theses - Archive

The main goal of the work is to present new procedures for statistical analysis of fabric data for structural geology. After an introduction to the problems of orientation analysis, discussion of different types of the orientation data and a brief review of the existing techniques and statistics for the orientation data, a comprehensive discussion of several proposed methods is given. The first part of the methodology chapter states a general model in terms of a structural frame and introduces some notation. The second part is a detailed description of a pooled estimator, which is intended to assess a structural frame …

Go to article

The Least-Squares Finite Element Method For Grid Deformation And Meshfree Applications, Dionisio Laeber Fleitas Jul 2005

The Least-Squares Finite Element Method For Grid Deformation And Meshfree Applications, Dionisio Laeber Fleitas

Mathematics Dissertations - Archive

Grid adaptation is often needed to improve the numerical solution of a Partial Differential Equation (PDE), due to, for example, shock waves and boundary layers. In moving boundary problems, the grid needs to be regenerated or adapted to fit the new domain. In this work, a LSFEM deformation method is developed for grid generation on fixed or moving domains. The LSFEM is a finite-elements method which seeks to minimize the PDE residual equation through the least-squares method. A new class of numerical methods currently being researched is the meshfree methods, in which the main goal is to numerically solve PDEs …

Go to article

Automating Inhabitant Interactions In Home And Workplace Environments Through Data-Driven Generation Of Hierarchical Partially-Observable Markov Decision Processes, Gregory Michael Youngblood Jul 2005

Automating Inhabitant Interactions In Home And Workplace Environments Through Data-Driven Generation Of Hierarchical Partially-Observable Markov Decision Processes, Gregory Michael Youngblood

Computer Science and Engineering Dissertations - Archive

Markov models provide a useful representation of system behavioral actions and state observations, but they do not scale well. Utilizing a hierarchy and abstraction through hierarchical hidden Markov models (HHMMs) improves scalability, but these structures are usually constructed manually using knowledge engineering techniques. We introduce a new method of automatically constructing HHMMs using the output of a sequential data-mining algorithm, Episode Discovery, and apply it to solving automation problems in the intelligent environment domain. Repetitive behavioral actions in sensor rich environments such as smart homes can be observed and categorized into periodic and frequent episodes through data-mining techniques utilizing the …

Go to article

A First-Principles Study On Bulk Cuo: Electronic Structures And Native Point Defects, Dangxin Wu Jul 2005

A First-Principles Study On Bulk Cuo: Electronic Structures And Native Point Defects, Dangxin Wu

Physics Theses - Archive

In this thesis, we have performed a first-principles study on strongly correlated monoclinic cupric oxide (CuO) by using the LSDA+U method implemented in the PAW method. Based on the optimized structural parameters, which are in good agreement with the experimental data, the electronic structure and the magnetic properties are obtained. Our calculations show that CuO is a semiconducting material with an indirect gap of about 1.0 eV. The semiconducting nature of CuO from our calculations is consistent with many experiments, but is qualitatively different from the LSDA calculations which incorrectly predict CuO to be metallic. The indirect gap of 1.0 …

Go to article

A Framework For Model Checking Object Oriented Security Protocol Implementations, Parikshit Singh Jun 2005

A Framework For Model Checking Object Oriented Security Protocol Implementations, Parikshit Singh

Computer Science and Engineering Theses - Archive

With the rapid growth of the Internet, more and more vendors see the Internet as a viable marketplace. Since the Internet is public, providing security in the presence of malicious intruders has become paramount. Security protocols have been proposed to protect systems. These protocols work by exchanging messages, many of which are encrypted. Though it may take a long time for an intruder to break the underlying encryption employed by the protocol, it is possible for the intruder to intervene in the authentication process. It may take years before a crucial loophole is discovered in a security protocol. Until then, …

Go to article

Proceedings Of The Ieee Southeastcon 2005, Yair Levy Apr 2005

Proceedings Of The Ieee Southeastcon 2005, Yair Levy

CCE Faculty Books and Book Chapters

No abstract provided.

Go to article

A Solvent-Free Baeyer–Villiger Lactonization For The Undergraduate Organic Laboratory: Synthesis Of Γ-T-Butyl-Ε-Caprolactone, John J. Esteb, James N. Hohman, Diana E. Schladaminger, Anne M. Wilson Jan 2005

A Solvent-Free Baeyer–Villiger Lactonization For The Undergraduate Organic Laboratory: Synthesis Of Γ-T-Butyl-Ε-Caprolactone, John J. Esteb, James N. Hohman, Diana E. Schladaminger, Anne M. Wilson

Scholarship and Professional Work - LAS

We present an experiment involving the Baeyer–Villiger oxidation reactionfor a first-year organic chemistry class. The Baeyer–Villiger reactionprovides an efficient method to convert ketones to esters or lactones. Most organictextbooks cover the Baeyer–Villiger reaction but owing to a lack of suitableexperiments, students seldom get to explore the reaction in the undergraduateteaching laboratory. In this experiment, m-chloroperoxybenzoic acid(m-CPBA) and4-tert-butylcyclohexanone are mixed together for 30 minutes under solvent-freeconditions to produce γ-t-butyl-ε-caprolactone in 95%yield. The solvent-free nature of this procedure greatly limits the quantityof waste generated by students and keeps costs low by removing the need for solvent.

Go to article

Technological Implications For Privacy, David Kotz Jun 2004

Technological Implications For Privacy, David Kotz

Computer Science Technical Reports

The World-Wide Web is increasingly used for commerce and access to personal information stored in databases. Although the Web is ``just another medium'' for information exchange, the fact that all the information is stored in computers, and all of the activity happens in computers and computer networks, makes it easier (cheaper) than every to track users' activities. By recording and analyzing user's activities in the Web, activities that may seem to be quite private to many users, it is more likely than ever before that a person's privacy may be threatened. In this paper I examine some of the technology …

Go to article

0610-2152b_Nir_Stis, D. A. Golimowski Jun 2004

0610-2152b_Nir_Stis, D. A. Golimowski

Publications and Research

No abstract provided.

Go to article

Base And Subbase In A Number System, Walter S. Sizer Jan 2004

Base And Subbase In A Number System, Walter S. Sizer

Humanistic Mathematics Network Journal

No abstract provided.

Go to article

Book Review: Fermat's Enigma By Simon Singh, Matthew Becker Jan 2004

Book Review: Fermat's Enigma By Simon Singh, Matthew Becker

Humanistic Mathematics Network Journal

No abstract provided.

Go to article

Are You A Quantitative Or Qualitative Runner?: 5.13 Miles And Rosemary-Lilac Shampoo, Shelly Sheats Harkness Jan 2004

Are You A Quantitative Or Qualitative Runner?: 5.13 Miles And Rosemary-Lilac Shampoo, Shelly Sheats Harkness

Humanistic Mathematics Network Journal

No abstract provided.

Go to article

2004 File Geodatabase Containing Photo Point Locations, Aerial Photos, And Flight Maps, City Of Tampa Department Of Sanitary Sewers Bay Study Group, Pete Reehling, Richard Mckenzie Jan 2004

2004 File Geodatabase Containing Photo Point Locations, Aerial Photos, And Flight Maps, City Of Tampa Department Of Sanitary Sewers Bay Study Group, Pete Reehling, Richard Mckenzie

Data Sets

The Bay Study Group was created by the City of Tampa in 1976 to monitor the effects of pollution abatement that occurred in Hillsborough Bay when the city’s wastewater treatment plant was upgraded from primary to advanced treatment in 1979. The Bay Study Group documented a remarkable restoration of water quality parameters and biological indicators in Hillsborough Bay from the mid 1980s until 2009, when it was disbanded. This zip Geodatabase file contains the photo point locations, aerial photos, and flight maps for the year 2004.

Go to article

2004 File Geodatabase Containing Aerial Photos, Pete Reehling, Richard Mckenzie, City Of Tampa Department Of Sanitary Sewers Bay Study Group Jan 2004

2004 File Geodatabase Containing Aerial Photos, Pete Reehling, Richard Mckenzie, City Of Tampa Department Of Sanitary Sewers Bay Study Group

Images

The Bay Study Group was created by the City of Tampa in 1976 to monitor the effects of pollution abatement that occurred in Hillsborough Bay when the city’s wastewater treatment plant was upgraded from primary to advanced treatment in 1979. The Bay Study Group documented a remarkable restoration of water quality parameters and biological indicators in Hillsborough Bay from the mid 1980s until 2009, when it was disbanded. This zip Geodatabase file contains the aerial photos for the year 2004.

Go to article

Solvent-Free Conversion Of Alpha-Naphthaldehyde To 1-Naphthoic Acid And 1-Naphthalenemethanol: Application Of The Cannizzaro Reaction, John J. Esteb, Keith M. Glogorich, Stacey A. O'Reilly Jan 2004

Solvent-Free Conversion Of Alpha-Naphthaldehyde To 1-Naphthoic Acid And 1-Naphthalenemethanol: Application Of The Cannizzaro Reaction, John J. Esteb, Keith M. Glogorich, Stacey A. O'Reilly

Scholarship and Professional Work - LAS

The Cannizzaro reaction is routinely covered in organic textbooks, but owing to the shortage of suitable procedures for the undergraduate teaching laboratory, this reaction is seldom performed in a first-year organic chemistry class. In this experiment, powdered potassium hydroxide and α-naphthaldehyde are heated under solvent-free conditions to produce 1-naphthoic acid and 1-naphthalenemethanol in 86% and 79% yields, respectively. The solvent-free nature of this procedure greatly reduces the quantity of waste generated by students relative to the typical solvent-based method of preparation. Note:Link is to the article in a subscription database available to users affiliated with Butler University. Appropriate login information …

Go to article

First Prev Next Last