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Articles 2161 - 2190 of 2906

Full-Text Articles in Physical Sciences and Mathematics

Contrasting Silicic Magma Series In Miocene-Pliocene Ash Deposits In The San Miguel De Allende Graben, Guanajuato, Mexico, Eric H. Christiansen, Bart J. Kowallis, Aaron J. Adams, Oscar Carranza-Castaneda, Wade E. Miller Mar 2006

Contrasting Silicic Magma Series In Miocene-Pliocene Ash Deposits In The San Miguel De Allende Graben, Guanajuato, Mexico, Eric H. Christiansen, Bart J. Kowallis, Aaron J. Adams, Oscar Carranza-Castaneda, Wade E. Miller

Faculty Publications

The San Miguel de Allende graben, Guanajuato, Mexico, contains numerous rhyolitic volcanic ash beds. Electron microprobe and x-ray fluorescence analyses of glass shards from 14 localities, combined with mineralogic, stratigraphic, radiometric, and paleomagnetic data, allow us to correlate the ash beds (and the intervening sedimentary strata and fossils), understand the timing of volcanism, date the age of extension, and better understand the tectonic and volcanic evolution of central Mexico. Our analyses reveal that at least six separate eruptions of rhyolitic ash occurred during the Late Miocene and Pliocene (5-3 Ma) while the San Miguel Allende basin was subsiding. The fallout …

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A Selective Approach To Bandwidth Overbooking, Feng Huang Mar 2006

A Selective Approach To Bandwidth Overbooking, Feng Huang

Theses and Dissertations

Overbooking is a technique used by network providers to increase bandwidth utilization. If the overbooking factor is chosen appropriately, additional virtual circuits can be admitted without degrading quality of service for existing customers. Most existing implementations use a single factor to accept a linear fraction of traffic requests. High values of this factor may cause the degradation of quality of service whereas low overbooking factors will result in underutilization of bandwidth. Network providers often select overbooking factors based only on aggregate average virtual circuit utilization. This paper proposes a selective overbooking scheme based on trunk size and usage profile. Experiments …

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Learning Real-World Problems By Finding Correlated Basis Functions, Adam C. Drake Mar 2006

Learning Real-World Problems By Finding Correlated Basis Functions, Adam C. Drake

Theses and Dissertations

Learning algorithms based on the Fourier transform attempt to learn functions by approximating the largest coefficients of their Fourier representations. Nearly all previous work in Fourier-based learning has been in the theoretical realm, where properties of the transform have made it possible to prove many interesting learnability results. The real-world usefulness of Fourier-based methods, however, has not been thoroughly explored. This thesis explores methods for the practical application of Fourier-based learning. The primary contribution of this thesis is a new search algorithm for finding the largest coefficients of a function's Fourier representation. Although the search space is exponentially large, empirical …

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User Datagram Protocol With Congestion Control, Spencer L. Cox Mar 2006

User Datagram Protocol With Congestion Control, Spencer L. Cox

Theses and Dissertations

Communication through the Internet is one of the dominant methods of exchanging information. Whether at an individual or large corporate level the Internet has become essential to gathering and disseminating information. TCP and UDP are the transport layer protocols responsible for transit of nearly all Internet communications. Due to the growth of real-time audio and video applications, UDP is being used more frequently as a transport protocol. As UDP traffic increases potential problems arise. Unlike TCP, UDP has no mechanism for congestion control leading to wasted bandwidth and poor performance for other competing protocols. This thesis defines a congestion control …

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Browser-Based Trust Negotiation, Cameron Morris Mar 2006

Browser-Based Trust Negotiation, Cameron Morris

Theses and Dissertations

Trust negotiation allows two parties on the Internet to establish trust in each other according to the digital credentials thateach other possesses. Traditionally, trust negotiation uses certificates as digital credentials. However, certificates make trust negotiation difficult to use since people rarely have certificates available to them, and they must physically possess and secure all needed certificates in order to negotiate. To avoid these problems, this thesis proposes that credential authorities negotiate on behalf of the user. This thesis defines BrowserBased Trust Negotiation (BBTN) as a method for negotiating with credential authorities using the Secure Assertion Markup Language (SAML).

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Encryption Of Computer Peripheral Devices, Kelly Robert Norman Mar 2006

Encryption Of Computer Peripheral Devices, Kelly Robert Norman

Theses and Dissertations

Computer peripherals, such as keyboards, scanners, printers, cameras, and Personal Data Assistants (PDAs) typically communicate with a host PC via an unencrypted protocol, leaving them vulnerable to eavesdropping techniques, such as keyloggers. An encryption system was developed that is simple enough to be used in peripherals that do not have large amounts of processing power and memory. A software driver loaded in the operating system of the host computer communicates with a simple 8-bit microcontroller in the peripheral device. The driver handles key generation, key exchange, and provides decrypted data to the operating system. A key exchange protocol allows the …

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Membrane-Based Protein Preconcentration Microfluidic Devices, Yi Li Mar 2006

Membrane-Based Protein Preconcentration Microfluidic Devices, Yi Li

Theses and Dissertations

Interest in microchip capillary electrophoresis (CE) is growing due to the rapid analysis times provided and small sample input requirements. However, higher-concentration samples are typically needed because of the small (~pL) detection volumes in these devices. I have made membrane-based protein preconcentration systems in capillary and microchip designs to increase the detectability of low-concentration biological samples. A photopolymerized ion-permeable membrane interfaced with a microchannel in poly(methyl methacrylate) (PMMA) formed the preconcentrator. When a voltage was applied between the sample reservoir and the ionically conductive membrane in a capillary-based system, R-phycoerythrin was concentrated more than 1,000 fold, as determined by laser-induced …

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A Multidisciplinary Approach To Reservoir Characterization Of The Coastal Entrada Erg-Margin Gas Play, Utah, Will D. Monn Mar 2006

A Multidisciplinary Approach To Reservoir Characterization Of The Coastal Entrada Erg-Margin Gas Play, Utah, Will D. Monn

Theses and Dissertations

World-class outcrops of an outermost erg-margin can be observed within the Middle Jurassic Entrada Sandstone near Capitol Reef National Park, Utah. These erg-margin deposits contain isolated reservoir quality sandstone bodies that transition into a muddy tidal flat facies. These high quality reservoirs are dominated by eolian-influenced facies interbedded with sandy interdune facies. They are sealed vertically by muddy and silty facies of associated tidal flat deposits that act as excellent stratigraphic traps in the subsurface. A variety of approaches were used to characterize these Entrada erg-margin reservoirs including: annotated panoramas of outcrops, measured sections, scintillometer measurements of field sections, facies …

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Mineral-Scale Sr Isotopic Study Of Plagioclase In The Mafic Dikes Of The North American Wall And The Diorite Of The Rockslides, Yosemite Valley, California., Wendy Rae Nelson Mar 2006

Mineral-Scale Sr Isotopic Study Of Plagioclase In The Mafic Dikes Of The North American Wall And The Diorite Of The Rockslides, Yosemite Valley, California., Wendy Rae Nelson

Theses and Dissertations

The North American Wall mafic dikes and the diorite of the Rockslides mafic complex in the intrusive suite of Yosemite Valley show evidence of mixing with their host granites as well as with earlier components. Whole rock major element variation diagrams indicate the mafic rocks mixed with a more silicic component, but extrapolating to the silica end member does not yield the same result with each element. Trace element concentrations show a wide variation in concentration of Cr and Ni, with two samples showing enrichment in Cr (>300 ppm) and Ni (~44 ppm) compared to other samples (Cr =13-94 …

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Unresolved Problems Involving The Hydrogeology And Sequence Stratigraphy Of The Wasatch Plateau Based On Mapping Of The Wattis 7.5 Minute Quadrangle, Carbon And Emery Counties, Utah: Insights Gained From A New Geologic Map, David O. Alderks Mar 2006

Unresolved Problems Involving The Hydrogeology And Sequence Stratigraphy Of The Wasatch Plateau Based On Mapping Of The Wattis 7.5 Minute Quadrangle, Carbon And Emery Counties, Utah: Insights Gained From A New Geologic Map, David O. Alderks

Theses and Dissertations

The Wattis 7.5 Minute Quadrangle is located in central Utah, in the transition zone between the Basin and Range province and the Colorado plateau. Two small grabens, located in the quadrangle, are the easternmost evidence of Basin and Range faulting. Sedimentary units exposed are mainly Cretaceous in age and deposited in the Western Cretaceous Interior Seaway. This area is of economical importance due to its large coal deposits, coal bed methane, and groundwater. The Wattis Quadrangle provided an ideal opportunity to test, at a small scale, the applicability of a new groundwater model for stratified mountainous terranes. Water samples had …

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The Violation Of Bell's Inequality In A Deterministic But Nonlocal Model, Stephanie Allred Magleby Mar 2006

The Violation Of Bell's Inequality In A Deterministic But Nonlocal Model, Stephanie Allred Magleby

Theses and Dissertations

This thesis investigates the violation of Bell's Inequality through the use of nonlocal measurement schemes as encapsulated in a quasi-deterministic toy model. This toy model, called the Q Box, is reminiscent of Mermin's Box in that it describes a system that appears to be deterministic yet produces the statistics of a quantum type system. [1] The workings of the Q Box are detailed both as a thought experiment and as a computer simulation. Nonlocal measurement protocols similar to those which generate a violation of Bell's Inequality in the Q Box are also applied to Mermin's Box, with comparable results. [1] …

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Surface Realization Using A Featurized Syntactic Statistical Language Model, Thomas L. Packer Mar 2006

Surface Realization Using A Featurized Syntactic Statistical Language Model, Thomas L. Packer

Theses and Dissertations

An important challenge in natural language surface realization is the generation of grammatical sentences from incomplete sentence plans. Realization can be broken into a two-stage process consisting of an over-generating rule-based module followed by a ranker that outputs the most probable candidate sentence based on a statistical language model. Thus far, an n-gram language model has been evaluated in this context. More sophisticated syntactic knowledge is expected to improve such a ranker. In this thesis, a new language model based on featurized functional dependency syntax was developed and evaluated. Generation accuracies and cross-entropy for the new language model did not …

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Modeling The Performance Of A Baseball Player's Offensive Production, Michael Ross Smith Mar 2006

Modeling The Performance Of A Baseball Player's Offensive Production, Michael Ross Smith

Theses and Dissertations

This project addresses the problem of comparing the offensive abilities of players from different eras in Major League Baseball (MLB). We will study players from the perspective of an overall offensive summary statistic that is highly linked with scoring runs, or the Berry Value. We will build an additive model to estimate the innate ability of the player, the effect of the relative level of competition of each season, and the effect of age on performance using piecewise age curves. Using Hierarchical Bayes methodology with Gibbs sampling, we model each of these effects for each individual. The results of the …

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Design And Measurement Of A Real-Time Peer-To-Peer Game, Michael D. Simonsen Mar 2006

Design And Measurement Of A Real-Time Peer-To-Peer Game, Michael D. Simonsen

Theses and Dissertations

Currently, multiplayer online games use the client-server architecture which is very resource intensive, expensive, and time consuming. Peer-to-peer protocols are a less resource intensive alternative to the client-server model. We implement a peer-to-peer protocol called NEO in a multiplayer game and run experiments in a lab setting and over the Internet. These experiments show us that NEO is able to run a smooth playable game, with low unused updates and low location error. This happens as long as the arrival delay is long enough to allow updates to arrive in the given time limit and the round length is short …

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Learning Real-Time A* Path Planner For Unmanned Air Vehicle Target Sensing, Jason K. Howlett, Timothy W. Mclain, Michael A. Goodrich Mar 2006

Learning Real-Time A* Path Planner For Unmanned Air Vehicle Target Sensing, Jason K. Howlett, Timothy W. Mclain, Michael A. Goodrich

Faculty Publications

This paper presents a path planner for sensing closely-spaced targets from a fixed-wing unmanned air vehicle (UAV) having a specified sensor footprint. The planner is based on the learning real-time A* (LRTA*) search algorithm and produces dynamically feasible paths that accomplish the sensing objectives in the shortest possible distance. A tree of candidate paths that span the area of interest is created by assembling primitive turn and straight sections of a specified step size in a sequential fashion from the starting position of the UAV. An LRTA* search of the tree produces feasible paths any time during its execution and …

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Measurement, Characterization, And Source Apportionment Of The Major Chemical Components Of Fine Particulate Material, Including Semi-Volatile Species, Brett D. Grover Feb 2006

Measurement, Characterization, And Source Apportionment Of The Major Chemical Components Of Fine Particulate Material, Including Semi-Volatile Species, Brett D. Grover

Theses and Dissertations

The promulgation of revised standards for atmospheric fine particles (PM2.5) by the US EPA has sparked renewed interest in the ability to accurately measure and characterize suspended atmospheric particulate matter. Semi-volatile material (SVM), consisting of ammonium nitrate and semi-volatile organic material (SVOM), is not accurately measured by EPA accepted methods such as the Federal reference method (FRM) or Tapered Element Oscillating Microbalance (TEOM). However, SVM is often a major fraction of urban aerosols. Recent advances in atmospheric sampling instrumentation allowed for the semi-continuous characterization of urban PM2.5, including SVM. The Filter Dynamic Measurement System (FDMS) was shown to measure total …

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Compact Solid-State Laser Source For 1s-2s Spectroscopy In Atomic Hydrogen, Scott D. Bergeson, N. Kolachevsky, J. Alnis, T. W. Hansch Feb 2006

Compact Solid-State Laser Source For 1s-2s Spectroscopy In Atomic Hydrogen, Scott D. Bergeson, N. Kolachevsky, J. Alnis, T. W. Hansch

Faculty Publications

We demonstrate a compact solid-state laser source for high-resolution two-photon spectroscopy of the 1S-2S transition in atomic hydrogen. The source emits up to 20 mW at 243 nm and consists of a 972 nm diode laser, a tapered amplifier, and two doubling stages. The diode laser is actively stabilized to a high-finesse cavity. We compare the new source to the stable 486 nm dye laser used in previous experiments and record 1S-2S spectra using both systems. With the solid-state laser system, we demonstrate a resolution of the hydrogen spectrometer of 6×10^11, which is promising for a number of high-precision measurements …

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Finding The Radial Parallel Temperature Profile In A Non-Neutral Plasma Using Equilibrium Calculations On Experimental Data, Grant W. Hart, Bryan G. Peterson Feb 2006

Finding The Radial Parallel Temperature Profile In A Non-Neutral Plasma Using Equilibrium Calculations On Experimental Data, Grant W. Hart, Bryan G. Peterson

Faculty Publications

In 1992, Eggleston et al. [D. L. Eggleston et al., Phys. Fluids B 4, 3432 (1992)] reported on a technique for measuring the radial temperature profile in a pure-electron plasma confined in a Malmberg-Penning trap by partially dumping the plasma onto a charge collector at the end of the trap. For short plasmas and short confining rings, the assumptions in their paper are violated and a more general calculation is needed. This paper presents a variation of the standard equilibrium calculation to find the temperature profile of a pure-electron plasma. Eggleston's shortcut "evaporation" temperature method is found to require a …

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Using Augmented Virtuality To Improve Human-Robot Interactions, Curtis W. Nielsen Feb 2006

Using Augmented Virtuality To Improve Human-Robot Interactions, Curtis W. Nielsen

Theses and Dissertations

Mobile robots can be used in situations and environments that are distant from an operator. In order for an operator to control a robot effectively he or she requires an understanding of the environment and situation around the robot. Since the robot is at a remote distant from the operator and cannot be directly observed, the information necessary for an operator to develop an understanding or awareness of the robot's situation comes from the user interface. The usefulness of the interface depends on the manner in which the information from the remote environment is presented. Conventional interfaces for interacting with …

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Characterization, Functionalization And Applications Of Alkyl Monolayers On Silicon Surfaces, Guilin Jiang Feb 2006

Characterization, Functionalization And Applications Of Alkyl Monolayers On Silicon Surfaces, Guilin Jiang

Theses and Dissertations

Investigations were performed on the stability, mechanism of formation and an application of alkyl monolayers chemomechanically prepared on silicon surfaces. A new method of surface modification, laser-activation modification of surfaces (LAMS), and multivariate analyses of time-of-flight secondary ion mass spectrometry (ToF-SIMS) images of LAMS spots were also reported. X-ray photoelectron spectroscopy (XPS) and other data show that alkyl monolayers prepared by scribing silicon under 1-iodoalkanes and 1-alkenes were stable over extended periods of time to air, water, a boiling acid and Al Ka X-rays. The stability is attributed to direct Si-C bonding in the monolayers. The observation that the oxygen …

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Correlating Factors Between Student Participation And Student Learning Via A Service Learning Project In Secondary Education: A Case Study, Shawn V. Jensen Jan 2006

Correlating Factors Between Student Participation And Student Learning Via A Service Learning Project In Secondary Education: A Case Study, Shawn V. Jensen

Theses and Dissertations

In this study a service-learning project was conducted with secondary students in a construction technology based course. Three research questions were considered; (1) does service learning projects help to engage student participation, (2) can students learn the course curriculum while participating in a service learning project, and (3) is there a correlation between student participation and student learning as it pertains to service learning projects? The data was collected through surveys, observations, interviews, and evaluations. The researcher concluded the following from the study; 92% of the students were actively participating in the two week service project, 76% of the students …

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A User-Centric Tabular Multi-Column Sorting Interface For Intact Transposition Of Columnar Data, David B. L. Miles Jan 2006

A User-Centric Tabular Multi-Column Sorting Interface For Intact Transposition Of Columnar Data, David B. L. Miles

Theses and Dissertations

Many usability features designed in software applications are not procedurally intuitive for software users. A good example of software usability involves tabular sorting in a spreadsheet. Single-column sorting, activated with a mouse click to a column header or toolbar button, often produces rearranged listings that reduce cognitive organization beyond the sorted column. Multi-column sorting, generated through menu-driven processes, provides derived organization, however, locating feature options through menu-based systems can be confusing. A means to overcome this confusion is prioritized selection of database arrays issued to columnar displays for the purpose of intact transposition of data. This is a unique process …

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The "Fair" Triathlon: Equating Standard Deviations Using Bayesian Nonlinear Models, Gilbert W. Fellingham, C. Shane Reese, S. Mckay Curtis Jan 2006

The "Fair" Triathlon: Equating Standard Deviations Using Bayesian Nonlinear Models, Gilbert W. Fellingham, C. Shane Reese, S. Mckay Curtis

Faculty Publications

The Ironman triathlon was created in 1978 by combining events with the longest distances for races then contested in Hawaii in swimming, cycling, and running. The Half Ironman triathlon was formed using half the distances of each of the events in the Ironman. The Olympic distance triathlon was created by combining events with the longest distances for races sanctioned by the major federations for swimming, cycling, and running. The relative importance of each event in overall race outcome was not given consideration when determining the distances of each of the races in modern triathlons. Thus, there is a general belief …

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Mathematically Modeling The Effects Of Counting Factor (Cf) In Dictyostelium Discoideum, J. C. Dallon, W. Jang, R. H. Gomer Jan 2006

Mathematically Modeling The Effects Of Counting Factor (Cf) In Dictyostelium Discoideum, J. C. Dallon, W. Jang, R. H. Gomer

Faculty Publications

Size regulation is a crucial feature in many biological systems, with misregulation leading to dysplasia or hyperplasia. The recent discovery of counting factor (CF) in Dictyostelium discoideum will lead to a greater understanding of how the system regulates the size of a group of cells. In this paper we mathematically model the known effects of CF using two different models: a cellular automata model and a discrete continuum hybrid model. With the use of these models we are able to understand how modulation of adhesion and motile forces by CF can facilitate stream breakup. In addition, the modelling suggests a …

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High-Temperature Calcium Vapor Cell For Spectroscopy On The 4s2 1s0-4s4p 3p1 Intercombination Line, Christopher J. Erickson, Brian Neyenhuis, Dallin S. Durfee Dec 2005

High-Temperature Calcium Vapor Cell For Spectroscopy On The 4s2 1s0-4s4p 3p1 Intercombination Line, Christopher J. Erickson, Brian Neyenhuis, Dallin S. Durfee

Faculty Publications

We have demonstrated a high-temperature vapor cell for absorption spectroscopy on the Ca intercombination line. The cell uses a dual-chamber design to achieve the high temperatures necessary for an optically dense vapor while avoiding the necessity of high-temperature vacuum valves and glass-to-metal seals. We have observed over 50% absorption in a single pass through the cell. Although pressure broadening in the cell prevented us from performing saturated-absorption spectroscopy, the broadening resulted in higher signal-to-noise ratios by allowing us to probe the atoms with intensities much greater than the 0.2µW/cm2 saturation intensity of the unbroadened transition. The techniques presented in this …

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Learning Successful Strategies In Repeated General-Sum Games, Jacob W. Crandall Dec 2005

Learning Successful Strategies In Repeated General-Sum Games, Jacob W. Crandall

Theses and Dissertations

Many environments in which an agent can use reinforcement learning techniques to learn profitable strategies are affected by other learning agents. These situations can be modeled as general-sum games. When playing repeated general-sum games with other learning agents, the goal of a self-interested learning agent is to maximize its own payoffs over time. Traditional reinforcement learning algorithms learn myopic strategies in these games. As a result, they learn strategies that produce undesirable results in many games. In this dissertation, we develop and analyze algorithms that learn non-myopic strategies when playing many important infinitely repeated general-sum games. We show that, in …

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Nonmetal Ordering In Tic1-Xnx: Ground-State Structure And The Effects Of Finite Temperature, Gus L. W. Hart, Brian Kolb Dec 2005

Nonmetal Ordering In Tic1-Xnx: Ground-State Structure And The Effects Of Finite Temperature, Gus L. W. Hart, Brian Kolb

Faculty Publications

The TiC1-xNx system has long been prized in industry because of its desirable thermodynamic and hardness characteristics. Previous studies have not produced comprehensive results describing the ordering tendencies of TiC1-xNx at any temperature. We apply the mixed-basis cluster expansion and Monte Carlo methods to the problem and find a fascinating array of ground-state structures occurring at precise nitrogen-concentration intervals of ∆x=1/16 and related to each other by simple (201) quasisuperlattice motifs. Thermodynamic Monte Carlo results indicate that the critical ordering temperatures at all concentrations are well below room temperature. short-range ordering develops at T ≈ 800 K and exhibits the …

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Electromagnetism In Gravitational Collapse, Craig Ernest Skinfill Dec 2005

Electromagnetism In Gravitational Collapse, Craig Ernest Skinfill

Theses and Dissertations

A numerical approach to including electromagnetism with general relativity is developed using GRAXI as a starting point. We develop a mathematical model describing electromagnetism coupled to a scalar field in an evolving axisymmetric spacetime. As there are numerous formulations of electromagnetism, we evalute different formulations in a limited flat space case. The full curved space system is then developed, using the flat case as a guide to implementing electromagnetism. This model is then implemented using GRAXI as a code base.

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Ultracold Neutral Plasma Expansion In Two Dimensions, E. A. Cummings, J. E. Daily, Dallin S. Durfee, Scott D. Bergeson Dec 2005

Ultracold Neutral Plasma Expansion In Two Dimensions, E. A. Cummings, J. E. Daily, Dallin S. Durfee, Scott D. Bergeson

Faculty Publications

An isothermal model of ultracold neutral plasma expansion is extended to systems without spherical symmetry. It is used to interpret new fluorescence measurements on ultracold neutral calcium plasmas. For a self-similar expansion, the fluid equations are solved both analytically and numerically. The density and velocity solutions are used to predict fluorescence signals induced by a laser beam weakly focused into the plasma. Despite the simplicity of the model, predicted fluorescence signals reproduce major features of the experimental data

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Trust Broker: A Defense Against Identity Theft From Online Transactions, Michael George Edvalson Dec 2005

Trust Broker: A Defense Against Identity Theft From Online Transactions, Michael George Edvalson

Theses and Dissertations

The proliferation of online services over the years has encouraged more and more people to participate in Internet activities. Many web sites request personal and sensitive information needed to deliver the desired service. Unfortunately, it is difficult to distinguish the sites that can be trusted to protect such information from those that cannot. Many attempts to make the Internet easier to use introduce new security and privacy problems. On the other hand, most attempts at creating a safe online environment produce systems that are cryptic and hard to use. The TrustBroker system is based on a specialized online repository that …

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