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Physical Sciences and Mathematics Commons™

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2008

Brigham Young University

Articles 1 - 30 of 118

Full-Text Articles in Physical Sciences and Mathematics

Towards The Total Synthesis Of Thioviridamide: Thiyl Radical Approach To The Beta-Thioenamide Linkage Formation, Jung-Hoon Kang Dec 2008

Towards The Total Synthesis Of Thioviridamide: Thiyl Radical Approach To The Beta-Thioenamide Linkage Formation, Jung-Hoon Kang

Theses and Dissertations

We developed an approach to the β-thioenamide linkage contained in the S-(2-aminovinyl)cysteine (avCys) residue of thioviridamide.1,2 Kinetic and thermodynamic control of radical additions of thiols to ynamides were studied for the formation of β-thioenamide linkage. Thiyl radicals are electrophilic and ynamides are electron-rich alkynes. This complementary polarity of the radical and acceptor increases the likelihood of a successful radical addition reaction. Because little is known about these types of compounds (β-thioenamides), we were unsure what kinds of yields and stereoselectivities (cis vs. trans) to expect. The adduct stability is another issue to consider. Fortunately, under typical radical addition conditions, the …

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Improving Library Searches Using Word-Correlation Factors And Folksonomies, Maria Soledad Pera Dec 2008

Improving Library Searches Using Word-Correlation Factors And Folksonomies, Maria Soledad Pera

Theses and Dissertations

Libraries, private and public, offer valuable resources to library patrons; however, formulating library queries to retrieve relevant results can be difficult. This occurs because when using a library catalog for library searches, patrons often do not know the exact keywords to be included in a query that match the rigid subject terms (chosen by the Library of Congress) or terms in other fields of a desired library catalog record. These improperly formulated queries often translate into a high percentage of failed searches that retrieve irrelevant results or no results at all. This explains why frustrated library patrons nowadays rely on …

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Ontology Generation, Information Harvesting And Semantic Annotation For Machine-Generated Web Pages, Cui Tao Dec 2008

Ontology Generation, Information Harvesting And Semantic Annotation For Machine-Generated Web Pages, Cui Tao

Theses and Dissertations

The current World Wide Web is a web of pages. Users have to guess possible keywords that might lead through search engines to the pages that contain information of interest and browse hundreds or even thousands of the returned pages in order to obtain what they want. This frustrating problem motivates an approach to turn the web of pages into a web of knowledge, so that web users can query the information of interest directly. This dissertation provides a step in this direction and a way to partially overcome the challenges. Specifically, this dissertation shows how to turn machine-generated web …

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Decision Tree Ensemble: Small Heterogeneous Is Better Than Large Homogeneous, Mike Gashler, Christophe G. Giraud-Carrier, Tony R. Martinez Dec 2008

Decision Tree Ensemble: Small Heterogeneous Is Better Than Large Homogeneous, Mike Gashler, Christophe G. Giraud-Carrier, Tony R. Martinez

Faculty Publications

Using decision trees that split on randomly selected attributes is one way to increase the diversity within an ensemble of decision trees. Another approach increases diversity by combining multiple tree algorithms. The random forest approach has become popular because it is simple and yields good results with common datasets. We present a technique that combines heterogeneous tree algorithms and contrast it with homogeneous forest algorithms. Our results indicate that random forests do poorly when faced with irrelevant attributes, while our heterogeneous technique handles them robustly. Further, we show that large ensembles of random trees are more susceptible to diminishing returns …

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Learning-Based Fusion For Data Deduplication, Sabra Dinerstein, Parris K. Egbert, Stephen W. Clyde, Jared Dinerstein Dec 2008

Learning-Based Fusion For Data Deduplication, Sabra Dinerstein, Parris K. Egbert, Stephen W. Clyde, Jared Dinerstein

Faculty Publications

Rule-based deduplication utilizes expert domain knowledge to identify and remove duplicate data records. Achieving high accuracy in a rule-based system requires the creation of rules containing a good combination of discriminatory clues. Unfortunately, accurate rule-based deduplication often requires significant manual tuning of both the rules and the corresponding thresholds. This need for manual tuning reduces the efficacy of rule-based deduplication and its applicability to real-world data sets. No adequate solution exists for this problem. We propose a novel technique for rule-based deduplication. We apply individual deduplication rules, and combine the resultant match scores via learning-based information fusion. We show empirically …

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Dynamic Load Balancing Of Virtual Machines Hosted On Xen, Terry Clyde Wilcox Dec 2008

Dynamic Load Balancing Of Virtual Machines Hosted On Xen, Terry Clyde Wilcox

Theses and Dissertations

Currently systems of virtual machines are load balanced statically which can create load imbalances for systems where the load changes dynamically over time. For throughput and response time of a system to be maximized it is necessary for load to be evenly distributed among each part of the system. We implement a prototype policy engine for the Xen virtual machine monitor which can dynamically load balance virtual machines. We compare the throughput and response time of our system using the cpu2000 and the WEB2005 benchmarks from SPEC. Under the loads we tested, dynamic load balancing had 5%-8% higher throughput than …

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Nowhere To Hide: Finding Plagiarized Documents Based On Sentence Similarity, Nathaniel Gustafson, Yiu-Kai D. Ng, Maria Soledad Pera Dec 2008

Nowhere To Hide: Finding Plagiarized Documents Based On Sentence Similarity, Nathaniel Gustafson, Yiu-Kai D. Ng, Maria Soledad Pera

Faculty Publications

Plagiarism is a serious problem that infringes copyrighted documents/materials, which is an unethical practice and decreases the economic incentive received by authors (owners) of the original copies. Unfortunately, plagiarism is getting worse due to the increasing number of online publications on the Web, which facilitates locating and paraphrasing information. In solving this problem, we propose a novel plagiarism-detection method, called SimPaD, which (i) establishes the degree of resemblance between any two documents D1 and D2 based on their sentence-to-sentence similarity computed by using pre-defined word-correlation factors, and (ii) generates a graphical view of sentences that are similar (or the same) …

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Using Geoscience Education Graduate Students To Help Faculty Transform Teaching Practice, Teagan L. Tomlin Dec 2008

Using Geoscience Education Graduate Students To Help Faculty Transform Teaching Practice, Teagan L. Tomlin

Theses and Dissertations

Universities make claims about student learning that graduates don't often achieve and are under pressure to show improvement in teaching and learning in their undergraduate programs. This has been the constant focus of university-level professional development programs, but most teachers are still not using the most effective teaching methods. Individual departments need to find ways to help their instructors overcome three main challenges associated with adopting more effective student-centered teaching methods. No matter what strategy is adopted, instructors need considerable support to 1) change their beliefs about what constitutes effective teaching and learning, 2) learn to effectively implement new strategies, …

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Simulation And Analysis Of Cadmium Sulfide Nanoparticles, Chad Everett Junkermeier Dec 2008

Simulation And Analysis Of Cadmium Sulfide Nanoparticles, Chad Everett Junkermeier

Theses and Dissertations

I used ab initio molecular dynamics calculations to model cadmium sulfide nanoparticles. The nanoparticles were originaly spherical, bulk-like zinc-blende structures. Constant temperature molecular dynamics calculations reveals that CdS nanoparticles that are about 2 nm in diameter and have unpassivated surfaces are in an amorphous structure with short range order. The nearest neighbor distance on the surface of the nanoparticles being near the wurtzite nearest neighbor distance. I wrote the program xyzSTATS and used its results in justifying the amorphous nanoparticles claim. I also estimated the band gap of the CdS nanoparticles with unpassivated dangling bonds.

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Sequence Alignment With Traceback On Reconfigurable Hardware, Scott Lloyd, Quinn O. Snell Dec 2008

Sequence Alignment With Traceback On Reconfigurable Hardware, Scott Lloyd, Quinn O. Snell

Faculty Publications

Biological sequence alignment is an essential tool used in molecular biology and biomedical applications. The growing volume of genetic data and the complexity of sequence alignment present a challenge in obtaining alignment results in a timely manner. Known methods to accelerate alignment on reconfigurable hardware only address sequence comparison, limit the sequence length, or exhibit memory and I/O bottlenecks. A space-efficient, global sequence alignment algorithm and architecture is presented that accelerates the forward scan and traceback in hardware without memory and I/O limitations. With 256 processing elements in FPGA technology, a performance gain over 300 times that of a desktop …

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Real-Time Automatic Price Prediction For Ebay Online Trading, Ilya Igorevitch Raykhel Nov 2008

Real-Time Automatic Price Prediction For Ebay Online Trading, Ilya Igorevitch Raykhel

Theses and Dissertations

While Machine Learning is one of the most popular research areas in Computer Science, there are still only a few deployed applications intended for use by the general public. We have developed an exemplary application that can be directly applied to eBay trading. Our system predicts how much an item would sell for on eBay based on that item's attributes. We ran our experiments on the eBay laptop category, with prior trades used as training data. The system implements a feature-weighted k-Nearest Neighbor algorithm, using genetic algorithms to determine feature weights. Our results demonstrate an average prediction error of 16%; …

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An Analysis Of Document Retrieval And Clustering Using An Effective Semantic Distance Measure, Nathan Scott Davis Nov 2008

An Analysis Of Document Retrieval And Clustering Using An Effective Semantic Distance Measure, Nathan Scott Davis

Theses and Dissertations

As large amounts of digital information become more and more accessible, the ability to effectively find relevant information is increasingly important. Search engines have historically performed well at finding relevant information by relying primarily on lexical and word based measures. Similarly, standard approaches to organizing and categorizing large amounts of textual information have previously relied on lexical and word based measures to perform grouping or classification tasks. Quite often, however, these processes take place without respect to semantics, or word meanings. This is perhaps due to the fact that the idea of meaningful similarity is naturally qualitative, and thus difficult …

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A See-Ability Metric To Improve Mini Unmanned Aerial Vehicle Operator Awareness Using Video Georegistered To Terrain Models, Cameron Howard Engh Nov 2008

A See-Ability Metric To Improve Mini Unmanned Aerial Vehicle Operator Awareness Using Video Georegistered To Terrain Models, Cameron Howard Engh

Theses and Dissertations

Search and rescue operations conducted in wilderness environments can be greatly aided by the use of video filmed from mini-UAVs. While lightweight, inexpensive and easily transportable, these small aircraft suffer from wind buffeting and may produce video that is difficult to search. To aid in the video search process, we have created a system to project video frames into a 3D representation of the search region. This projection allows us to tie each frame of video to a real-world location, enabling a myriad of novel views, mosaics and metrics that can be used to guide the search including a new …

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Parameter Estimation For The Beta Distribution, Claire Elayne Bangerter Owen Nov 2008

Parameter Estimation For The Beta Distribution, Claire Elayne Bangerter Owen

Theses and Dissertations

The beta distribution is useful in modeling continuous random variables that lie between 0 and 1, such as proportions and percentages. The beta distribution takes on many different shapes and may be described by two shape parameters, alpha and beta, that can be difficult to estimate. Maximum likelihood and method of moments estimation are possible, though method of moments is much more straightforward. We examine both of these methods here, and compare them to three more proposed methods of parameter estimation: 1) a method used in the Program Evaluation and Review Technique (PERT), 2) a modification of the two-sided power …

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The Hybrid Game Architecture: Distributing Bandwidth For Mmogs While Maintaining Central Control, Jared L. Jardine Nov 2008

The Hybrid Game Architecture: Distributing Bandwidth For Mmogs While Maintaining Central Control, Jared L. Jardine

Theses and Dissertations

Current Massively Multi-player Online Games (MMOGs) have enormous server-side bandwidth requirements. The costs of providing this bandwidth is in turn passed on to the consumer in the form of high monthly subscription fees. Prior work has primarily focused on distributing this bandwidth using peer-to-peer architectures, but these architectures have difficulty preventing cheating, overwhelming low resource peers, and maintaining consistent game state. We have developed a hybrid game architecture that combines client-server and peer-to-peer technologies to prevent cheating, maintain centralized and consistent game state, significantly reduce central server bandwidth, and prevent lower capacity players from being overwhelmed. By dramatically reducing the …

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Antiphase Ordering And Surface Phases In Lithium Aluminate, Richard R. Vanfleet, J. A. Simmons, D. W. Hill, M. M. C. Chou, B. H. Chai Nov 2008

Antiphase Ordering And Surface Phases In Lithium Aluminate, Richard R. Vanfleet, J. A. Simmons, D. W. Hill, M. M. C. Chou, B. H. Chai

Faculty Publications

Antiphase domains are seen in single crystal gamma lithium aluminate (gamma-LiAlO2) with 16.7 nm periodicity in the <110> direction. Alternate domains have a (1/2) [001] shift. Beta phase lithium aluminate (beta-LiAlO2) is seen to form on the surface of the as-received wafers with an epitaxial strain limited relationship with the bulk gamma phase. The orthorhombic beta phase aligns with the a and b axes (0.528 and 0.630 nm) matching with the tetragonal gamma phase's a and c axes (0.5168 and 0.6268 nm). The gamma and beta phases are seen to have different etch rates. The beta phase converts back to the …

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Investigating The Margins Of Pleistocene Lake Deposits With High-Resolution Seismic Reflection In Pilot Valley, Utah, John V. South Nov 2008

Investigating The Margins Of Pleistocene Lake Deposits With High-Resolution Seismic Reflection In Pilot Valley, Utah, John V. South

Theses and Dissertations

A vast area of the northeastern Great Basin of the western USA was inundated by a succession of Plio-Pleistocene lakes, including Lake Bonneville (28 ka to 12 ka). The Pilot Valley playa, located just east of the Utah-Nevada border near Wendover, Utah, within the eastern Basin and Range Province, represents an 8 to 16 km wide and ~50 km long remnant of these lakes. The playa corresponds to the upper surface of a closed basin that is delimited by two mountain ranges, which are mantled by recent alluvial fans over which the playa sediments have prograded. In order to investigate …

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Photocycloaddition Of Allenes, Crystal Ward Nov 2008

Photocycloaddition Of Allenes, Crystal Ward

Theses and Dissertations

For the past ten years the Fleming research group has been involved in the research of allene compounds. We have explored the synthesis of allenes as well as several reactions involving allenes, such as oxidation and nitrene addition. Recently, we have explored the synthesis and photochemistry of allenic alcohols tethered to silicon. There are literature examples using allenes in synthesis, but very few examples exist using allenes in photochemical cycloaddition reactions. We have found that a diisopropylallenyloxy(cinnamyloxy)silane derivative undergoes [2+2] photochemical cycloaddition to produce a cyclobutylsilane product when irradiated for 60-75 minutes.

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Wolfcampian Development Of The Nose Of The Eastern Shelf Of The Midland Basin, Glasscock, Sterling, And Reagan Counties, Texas, Douglas S. Flamm Nov 2008

Wolfcampian Development Of The Nose Of The Eastern Shelf Of The Midland Basin, Glasscock, Sterling, And Reagan Counties, Texas, Douglas S. Flamm

Theses and Dissertations

The nose of the Eastern shelf of the Midland Basin is a prominent structural and depositional feature present in Glasscock, Sterling, and Howard counties, Texas. This feature has been expressed in many regional maps and mentioned in some literature, but has not otherwise been studied significantly. This study looks at the viability of using an acoustic impedance seismic inversion to interpret the 2nd and 3rd order sequence stratigraphy of the southern portion of the nose of the Eastern shelf along with its shelf to basin transition in Glasscock, Sterling, and Reagan counties during the Wolfcampian (Asselian-Sakmarian) time (Early Permian). The …

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Extreme-Ultraviolet Polarimeter Utilizing Laser-Generated High-Order Harmonics, Nicole Brimhall, Matthew Turner, Nicholas Herrick, David D. Allred, R. Steven Turley, Michael Ware, Justin Peatross Oct 2008

Extreme-Ultraviolet Polarimeter Utilizing Laser-Generated High-Order Harmonics, Nicole Brimhall, Matthew Turner, Nicholas Herrick, David D. Allred, R. Steven Turley, Michael Ware, Justin Peatross

Faculty Publications

We describe an extreme-ultraviolet (EUV) polarimeter that employs laser-generated high-order harmonics as the light source. The polarimeter is designed to characterize materials and thin films for use with EUV light. Laser high harmonics are highly directional with easily rotatable linear polarization, not typically available with other EUV sources. The harmonics have good wavelength coverage, potentially spanning the entire EUV from a few to a hundred nanometers. Our instrument is configured to measure reflectances from 14 to 30 nm and has ~180 spectral resolution (lambda/delta lambda). The reflection from a sample surface can be measured over a continuous range of incident …

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Using Vagueness Measures To Re-Rank Documents Retrieved By A Fuzzy Set Information Retrieval Model, Stephen Lynn, Yiu-Kai D. Ng Oct 2008

Using Vagueness Measures To Re-Rank Documents Retrieved By A Fuzzy Set Information Retrieval Model, Stephen Lynn, Yiu-Kai D. Ng

Faculty Publications

Traditional information retrieval (IR) systems evaluate user queries and retrieve/rank documents based on matching keywords in user queries with words in documents. These exact word-matching and ranking approaches ignore too many relevant documents that do not contain the exact keywords as specified in a user query. Instead of considering these traditional approaches, we propose to retrieve documents using a fuzzy set IR model and rank retrieved documents for any vague query using the “vagueness score” of the documents based on the word senses as defined in WordNet. Using the vagueness scores, we rank the most highest “relevant” documents of a …

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Hop-By-Hop Multicast Transport For Mobile Ad Hoc Wireless Networks, Manoj Pandey, Daniel Zappala Oct 2008

Hop-By-Hop Multicast Transport For Mobile Ad Hoc Wireless Networks, Manoj Pandey, Daniel Zappala

Faculty Publications

Multicast transport is a challenging problem because the source must provide congestion control and reliability for a tree, rather than a single path. This problem is made even more difficult in mobile ad hoc networks due to problems caused by contention, spatial reuse, and mobility. In this paper, we design a hop-by-hop multicast transport protocol, which pushes transport functionality into the core of the network. Although this requires per-flow state, a hop-by-hop approach simplifies congestion control, enables local recovery of lost packets, and provides low delay and efficient use of wireless capacity. We use a simulation study to demonstrate the …

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Scalable Multicast Routing For Ad Hoc Networks, Manoj Pandey, Daniel Zappala Oct 2008

Scalable Multicast Routing For Ad Hoc Networks, Manoj Pandey, Daniel Zappala

Faculty Publications

Routing in a mobile ad hoc network is challenging because nodes can move at any time, invalidating a previously-discovered route. Multicast routing is even more challenging, because a source needs to maintain a route to potentially many group members simultaneously. Providing scalable solutions to this problem typically requires building a hierarchy or an overlay network to reduce the cost of route discovery and maintenance. In this paper, we show that a much simpler alternative is possible, by using source specific semantics and relying on the unicast routing protocol to find all routes. This separation of concerns enables the multicast routing …

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Enhancement Of Unusual Color In Aerial Video Sequences For Assisting Wilderness Search And Rescue, Bryan S. Morse, Nathan D. Rasmussen, Daniel Thornton Oct 2008

Enhancement Of Unusual Color In Aerial Video Sequences For Assisting Wilderness Search And Rescue, Bryan S. Morse, Nathan D. Rasmussen, Daniel Thornton

Faculty Publications

The use of aerial video for search and surveillance has been popularized by the increased use of camera-equipped unmanned aerial vehicles. For many search applications, objects may also be missed by observers due to their small size, brief visibility, or the inherent monotony of the scene. This paper presents a novel method for automatically emphasizing unusually colored objects to improve their detectability. We use a hue histogram and a local saliency measure to find unusually colored objects, then boost the saturation of these objects while desaturating more common colors, thus drawing the observer’s attention and facilitating video search.

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Autonomous And Intelligent Radio Switching For Heterogeneous Wireless Networks, Qiuyi Duan, Charles D. Knutson, Lei Wang, Daniel Zappala Sep 2008

Autonomous And Intelligent Radio Switching For Heterogeneous Wireless Networks, Qiuyi Duan, Charles D. Knutson, Lei Wang, Daniel Zappala

Faculty Publications

As wireless devices continue to become more prevalent, heterogeneous wireless networks - in which communicating devices have at their disposal multiple types of radios - will become the norm. Communication between nodes in these networks ought to be as simple as possible; they should be able to seamlessly switch between different radios and network stacks on the fly in order to better serve the user. To make this a possibility, we consider the challenging problems of when two communicating devices should decide to switch to a different radio, and which radio they should choose. We design an Autonomous and Intelligent …

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Improving Live Sequence Chart To Automata Transformation For Verification, Rahul Kumar, Eric G. Mercer Aug 2008

Improving Live Sequence Chart To Automata Transformation For Verification, Rahul Kumar, Eric G. Mercer

Faculty Publications

This paper presents a Live Sequence Chart (LSC) to automata transformation algorithm that enables the verification of communication protocol implementations. Using this LSC to automata transformation a communication protocol implementation can be verified using a single verification run as opposed to previous techniques that rely on a three stage verification approach. The novelty and simplicity of the transformation algorithm lies in its placement of accept states in the automata generated from the LSC. We present in detail an example of the transformation as well as the transformation algorithm. Further, we present a detailed analysis and an empirical study comparing the …

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Biologically Relevant Multiple Sequence Alignment, Hyrum D. Carroll Aug 2008

Biologically Relevant Multiple Sequence Alignment, Hyrum D. Carroll

Theses and Dissertations

Researchers use multiple sequence alignment algorithms to detect conserved regions in genetic sequences and to identify drug docking sites for drug development. In this dissertation, a novel algorithm is presented for using physicochemical properties to increase the accuracy of multiple sequence alignments. Secondary structures are also incorporated in the evaluation function. Additionally, the location of the secondary structures is assimilated into the function. Multiple properties are combined with weights, determined from prediction accuracies of protein secondary structures using artificial neural networks. A new metric, the PPD Score is developed, that captures the average change in physicochemical properties. Using the physicochemical …

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Testing Direct Simulation Monte Carlo Methods Against The Fluid Equations In The Inductively Coupled Plasma Mass Spectrometer, William R. Somers Aug 2008

Testing Direct Simulation Monte Carlo Methods Against The Fluid Equations In The Inductively Coupled Plasma Mass Spectrometer, William R. Somers

Theses and Dissertations

A Direct Simulation Monte Carlo fluid dynamics code named FENIX has been employed to study gas flow-through properties of the inductively coupled plasma mass spectrometer (ICP-MS). Simulation data have been tested against the Navier-Stokes and heat equations in order to see if FENIX functions properly. The Navier-Stokes and heat equations have been constructed from simulation data and are compared term by term. This comparison shows that FENIX is able to correctly reproduce fluid dynamics throughout the ICP-MS simulation, with an exception immediately behind the ICP-MS sampler cone, where the continuum criterion for the Navier-Stokes equation is not met. Testing the …

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Implementation Of Optical Spectra Calculations In Fireball: A Local-Orbital Density Functional Theory Approach, Ivan Grigoryevich Okhrimenko Aug 2008

Implementation Of Optical Spectra Calculations In Fireball: A Local-Orbital Density Functional Theory Approach, Ivan Grigoryevich Okhrimenko

Theses and Dissertations

We have expanded the capabilities of the ab initio tight-binding molecular dynamics package FIREBALL to include calculations of optical properties. Basic zero order approximation is based on transitions between Kohn-Sham states. Corrections for electron-electron interactions are based on time dependant density functional theory (TDDFT). Consistent with the FIREBALL approach, we use precalculated integrals and approximations to make the program faster.

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Recombination Fluorescence In Ultracold Neutral Plasmas, Scott D. Bergeson, F. Robicheaux Aug 2008

Recombination Fluorescence In Ultracold Neutral Plasmas, Scott D. Bergeson, F. Robicheaux

Faculty Publications

We present the first measurements and simulations of recombination fluorescence from ultracold neutral calcium plasmas. This method probes three-body recombination at times less than 1 µs, shorter than previously published time scales. For the lowest initial electron temperatures, the recombination rate scales with the density as n22, significantly slower than the predicted n3. Recombination fluorescence opens a new diagnostic window in ultracold plasmas. In most cases it probes deeply bound level populations that depend critically on electron energetics. However, a perturbation in the calcium 4snd Rydberg series allows our fluorescence measurements to probe the population in weakly bound levels that …

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