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Brigham Young University

2005

Articles 1 - 30 of 126

Full-Text Articles in Physical Sciences and Mathematics

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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Industrial Technology Education Teachers Perceptions Of National Standards For Technological Literacy In The State Of Arizona, Allan R. Mcrae Dec 2005

Industrial Technology Education Teachers Perceptions Of National Standards For Technological Literacy In The State Of Arizona, Allan R. Mcrae

Theses and Dissertations

Today, it is becoming increasingly clear that there is a growing interest, concern, and need for technological literacy. To this end, the International Technology Education Association (ITEA) through the Technology for All Americans Project, has developed and promulgated the Standards for Technological Literacy: Content for the Study of Technology. This effort is part of the ongoing initiative to develop technology standards on a national level, and to focus on what every student in grades K-12 should know and be able to do in order to achieve technological literacy (ITEA, 2000). The purpose of this study was to investigate the perceived …

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Autologous Stem Cell Transplant: Factors Predicting The Yield Of Cd34+ Cells, Elizabeth Anne Lawson Dec 2005

Autologous Stem Cell Transplant: Factors Predicting The Yield Of Cd34+ Cells, Elizabeth Anne Lawson

Theses and Dissertations

Stem cell transplant is often considered the last hope for the survival for many cancer patients. The CD34+ cell content of a collection of stem cells has appeared as the most reliable indicator of the quantity of desired cells in a peripheral blood stem cell harvest and is used as a surrogate measure of the sample quality. Factors predicting the yield of CD34+ cells in a collection are not yet fully understood. Throughout the literature, there has been conflicting evidence with regards to age, gender, disease status, and prior radiation. In addition to the factors that have already been explored, …

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Testing Primitive Polynomials For Generalized Feedback Shift Register Random Number Generators, Guinan Lian Nov 2005

Testing Primitive Polynomials For Generalized Feedback Shift Register Random Number Generators, Guinan Lian

Theses and Dissertations

The class of generalized feedback shift register (GFSR) random number generators was a promising method for random number generation in the 1980's, but was abandoned because of some flaws such as poor performance on certain tests for randomness. The poor performance may be due to the choice of primitive polynomials used in the generators, rather than inherent flaws in the method. The original GFSR generators were all based on primitive trinomials. This project examines several alternative choices of primitive polynomials with more than one "interior" term to address this problem and hopefully provide access to good random number generators.

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Fluorescence Measurements Of Expanding Strongly Coupled Neutral Plasmas, E. A. Cummings, J. E. Daily, Dallin S. Durfee, Scott D. Bergeson Nov 2005

Fluorescence Measurements Of Expanding Strongly Coupled Neutral Plasmas, E. A. Cummings, J. E. Daily, Dallin S. Durfee, Scott D. Bergeson

Faculty Publications

We report new detailed density profile measurements in expanding strongly coupled neutral calcium plasmas. Using laser-induced fluorescence techniques, we determine plasma densities in the range of 10^5 to 10^9 cm^-3 with a time resolution limit as small as 7 ns. Strong coupling in the plasma ions is inferred directly from the fluorescence signals. Evidence for strong coupling at late times is presented, confirming a recent theoretical result.

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Generating Data-Extraction Ontologies By Example, Yuanqiu Zhou Nov 2005

Generating Data-Extraction Ontologies By Example, Yuanqiu Zhou

Theses and Dissertations

Ontology-based data-extraction is a resilient web data-extraction approach. A major limitation of this approach is that ontology experts must manually develop and maintain data-extraction ontologies. The limitation prevents ordinary users who have little knowledge of conceptual models from making use of this resilient approach. In this thesis we have designed and implemented a general framework, OntoByE, to generate data-extraction ontologies semi-automatically through a small set of examples collected by users. With the assistance of a limited amount of prior knowledge, experimental evidence shows that OntoByE is capable of interacting with users to generate data-extraction ontologies for domains of interest to …

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A Software Development Environment For Building Context-Aware Systems For Family Technology, Jeremiah Kenton Jones Nov 2005

A Software Development Environment For Building Context-Aware Systems For Family Technology, Jeremiah Kenton Jones

Theses and Dissertations

The purpose of this thesis was to utilize existing technologies to create a development environment suitable for creating context-aware applications and systems specific to home and family living conditions. After outlining the history of context-aware applications and the challenges that face family-centric systems in this field, a development environment was implemented that solves the unique challenges that face application development for family-centric, context-aware applications. In particular, research cited in this document indicates that a browser-based user interface is the most appropriate interface for a family environment. The flexibility of the interface, as well as the familiarity of the application structure …

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Acoustics Of The Salt Lake Tabernacle: Characterization And Study Of Spatial Variation, Sarah Rollins Nov 2005

Acoustics Of The Salt Lake Tabernacle: Characterization And Study Of Spatial Variation, Sarah Rollins

Theses and Dissertations

In order to preserve the acoustics of the Salt Lake Tabernacle after the seismic renovation of 2005-2006, it was necessary to characterize these acoustics immediately preceding the renovation. This thesis discusses the characterization process that began with the measurement of hundreds of impulse responses for five different source positions and several receiver locations throughout the hall seating areas. The acoustics were further characterized by deriving various parameters from these responses that correlate with subjective preferences for music and speech. Impulse responses were also generated by a CATT-Acoustic™ computer model of the Tabernacle for the same purpose. The parameter values were …

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Classifcation Of Conics In The Tropical Projective Plane, Amanda Ellis Nov 2005

Classifcation Of Conics In The Tropical Projective Plane, Amanda Ellis

Theses and Dissertations

This paper defines tropical projective space, TP^n, and the tropical general linear group TPGL(n). After discussing some simple examples of tropical polynomials and their hypersurfaces, a strategy is given for finding all conics in the tropical projective plane. The classification of conics and an analysis of the coefficient space corresponding to such conics is given.

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The Role Of Phosducin-Like Protein And The Cytosolic Chaperonin Cct In G Beta Gamma Dimer Assembly, Ting Hu Nov 2005

The Role Of Phosducin-Like Protein And The Cytosolic Chaperonin Cct In G Beta Gamma Dimer Assembly, Ting Hu

Theses and Dissertations

Phosducin-like protein (PhLP), a G protein beta gamma subunit dimer binder and G protein signaling regulator, was suggested to regulate the activity of cytosolic chaperonin CCT by their high affinity interaction. In the present study, the three-dimensional structure of PhLP:CCT complex has been solved by cryoelectron microscopy. PhLP was found to bind only one of the chaperonin rings with both N- and C-terminal domains. It spans the central folding cavity of CCT and interacts with two opposite sides of the top apical region, inducing the constraining of the entry of the folding cavity. These findings support a putative role of …

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Relationship Between Fault Zone Architecture And Groundwater Compartmentalization In The East Tintic Mining District, Utah, Sandra Myrtle Conrad Hamaker Nov 2005

Relationship Between Fault Zone Architecture And Groundwater Compartmentalization In The East Tintic Mining District, Utah, Sandra Myrtle Conrad Hamaker

Theses and Dissertations

The Eureka Lilly fault zone provides an impermeable barrier for groundwater flow in the East Tintic mining district. The fault zone separates two distinct groundwaters that have different temperatures, compositions, and potentiometric surfaces. The damage zone of the fault is an extensive network of interconnected open fractures and fault intersections that provide conduits for groundwater flow in otherwise impermeable units. The fault core breccia has been re-cemented and mineralized, which eliminates porosity in the rock by creating a thick impermeable zone, which has compartmentalized groundwaters across the fault zone. The compartmentalization of groundwater shows that fault zone variability (from strain …

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Development Of Commercial Applications For Recycled Plastics Using Finite Element Analysis, Nanjunda Narasimhamurthy Nov 2005

Development Of Commercial Applications For Recycled Plastics Using Finite Element Analysis, Nanjunda Narasimhamurthy

Theses and Dissertations

This thesis investigates the suitability of thermo-kinetically recycled plastics for use in commercial product applications using finite element analysis and statistics. Different recycled material blends were tested and evaluated for their use in commercial product applications. There are six different blends of thermo-kinetically recycled plastics used for testing and CATIA is used for finite element analysis. The different types of thermo-kinetically recycled plastics blends are: pop bottles made of PolyethyleneTeraphthalate (PET), milk jugs made of High-Density Polyethylene (HDPE), Vinyl seats made of Poly Vinyl Chloride (PVC) and small amount of Polypropylene (PP) and Urethane, electronic scrap made of engineering resins …

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Generating Medical Logic Modules For Clinical Trial Eligibility, Craig G. Parker Nov 2005

Generating Medical Logic Modules For Clinical Trial Eligibility, Craig G. Parker

Theses and Dissertations

Clinical trials are important to the advancement of medical science. They provide the experimental and statistical basis needed to determine the benefit of diagnostic and therapeutic agents and procedures. The more patients enrolled in a clinical trial, the more confidence we can have in the trial's results. However, current practices for identifying eligible patients can be expensive and time-consuming. To assist in making identification of eligible patients more cost effective, we have developed a system for translating the eligibility criteria for clinical trials to an executable form. This system takes as input the eligibility criteria for a trial formatted as …

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Palladium-Imidazolium Carbene Catalyzed Heck Coupling Reactions And Synthesis Of A Novel Class Of Fluoroanthracenylmethyl Ptc Catalysts, Jiuqing Zhang Nov 2005

Palladium-Imidazolium Carbene Catalyzed Heck Coupling Reactions And Synthesis Of A Novel Class Of Fluoroanthracenylmethyl Ptc Catalysts, Jiuqing Zhang

Theses and Dissertations

Palladium catalyzed Heck coupling with aryl and alkenyl halides has become a powerful means of carbon-carbon bond formation. This standard synthetic method has been developed to a high level of utility using various catalysts, conditions and substrates. Yet significant drawbacks remain, including poor reactivity, the need for high temperatures and base, limited substrate generality, and selectivity. Mixed products often suffer from olefin migration following insertion. N-Heterocyclic carbenes (NHC) have proven to be electron-rich donors which provide higher stability and reactivity than phosphines. In a previous paper reported by our research group the imidazolium-palladium carbene has proven to be highly efficient …

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Verification Of Digital Controller Verifications, Xuan Wang Nov 2005

Verification Of Digital Controller Verifications, Xuan Wang

Theses and Dissertations

This thesis presents an analysis framework to verify the stablility property of a closed-loop control system with a software controller implementation. The usual approach to verifying stability for software uses experiments which are costly and can be dangerous. More recently, mathematical models of software have been proposed which can be used to reason about the correctness of controllers. However, these mathematical models ignore computational details that may be important in verification. We propose a method to determine the instability of a closed-loop system with a software controller implementation under l^2 inputs using simulation. This method avoids the cost of experimentation …

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Real-Time Motion Transition By Example, Cameron Quinn Egbert Nov 2005

Real-Time Motion Transition By Example, Cameron Quinn Egbert

Theses and Dissertations

Motion transitioning is a common task in real-time applications such as games. While most character motions can be created a priori using motion capture or hand animation, transitions between these motions must be created by an animation system at runtime. Because of this requirement, it is often difficult to create a transition that preserves the feel that the actor or animator has put into the motion. An additional difficulty is that transitions must be created in real-time. This paper provides a method of creating motion transitions that is both computationally feasible for interactive speeds, and preserves the feel of the …

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Modeling Distributions Of Test Scores With Mixtures Of Beta Distributions, Jingyu Feng Nov 2005

Modeling Distributions Of Test Scores With Mixtures Of Beta Distributions, Jingyu Feng

Theses and Dissertations

Test score distributions are used to make important instructional decisions about students. The test scores usually do not follow a normal distribution. In some cases, the scores appear to follow a bimodal distribution that can be modeled with a mixture of beta distributions. This bimodality may be due different levels of students' ability. The purpose of this study was to develop and apply statistical techniques for fitting beta mixtures and detecting bimodality in test score distributions. Maximum likelihood and Bayesian methods were used to estimate the five parameters of the beta mixture distribution for scores in four quizzes in a …

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Totally Real Galois Representations In Characteristic 2 And Arithmetic Cohomology, Heather Aurora Florence De Melo Nov 2005

Totally Real Galois Representations In Characteristic 2 And Arithmetic Cohomology, Heather Aurora Florence De Melo

Theses and Dissertations

The purpose of this paper is to provide new examples supporting a conjecture of Ash, Doud, and Pollack. This conjecture involves Galois representations taking Gal(Q bar/Q) to the general linear group of 3 x 3 matrices in characterisic 2, and our examples are where complex conjugation is mapped to the identity. Since this case has not yet been examined, the results of this paper are quite significant.

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Total Syntheses Of (+)-Geldanamycin, (-)-Ragaglitazar, And (+)-Kurasoin A And Phase-Transfer-Catalyzed Asymmetric Alkylation, Erik J. Hicken Nov 2005

Total Syntheses Of (+)-Geldanamycin, (-)-Ragaglitazar, And (+)-Kurasoin A And Phase-Transfer-Catalyzed Asymmetric Alkylation, Erik J. Hicken

Theses and Dissertations

Geldanamycin possesses various biological activities as seen in the NCI 60 cell line panel (13 nM avg., 70 nM SKBr-3 cells). The predominant mode of action providing these unique results arises from the ability of geldanamycin (GA) to bind to the chaperone heat shock protein 90 (Hsp90). Despite its complicated functionality, the first total synthesis of GA was accomplished, which included two new reactions developed specifically to address the stereochemical features. The final step in the synthesis of GA was a demethylation-oxidation sequence to generate the desired para-quinone. This step could only be accomplished with HNO3/AcOH, producing GA in …

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A Context-Sensitive Structural Heuristic For Guided Search Model Checking, Eric G. Mercer, Neha Rungta Nov 2005

A Context-Sensitive Structural Heuristic For Guided Search Model Checking, Eric G. Mercer, Neha Rungta

Faculty Publications

Software verification using model checking often translates programs into corresponding transition systems that model the program behavior. As software systems continue to grow in complexity and size, exhaustively checking a property on a transition graph becomes difficult. The goal of guided search heuristics in model checking is to find a counterexample to the property being verified as quickly as possible in the transition graph. The FSM distance heuristic builds an interprocedural control flow graph of the program to estimate distance to a possible error state. It ignores calling context and underestimates the true distance to the error.

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Using Genetic Algorithms To Map First-Principles Results To Model Hamiltonians: Application To The Generalized Ising Model For Alloys, Gus L. W. Hart, Volker Blum, Michael J. Walorski, Alex Zunger Oct 2005

Using Genetic Algorithms To Map First-Principles Results To Model Hamiltonians: Application To The Generalized Ising Model For Alloys, Gus L. W. Hart, Volker Blum, Michael J. Walorski, Alex Zunger

Faculty Publications

The cluster expansion method provides a standard framework to map first-principles generated energies for a few selected configurations of a binary alloy onto a finite set of pair and many-body interactions between the alloyed elements. These interactions describe the energetics of all possible configurations of the same alloy, which can hence be readily used to identify ground state structures and, through statistical mechanics solutions, find finite-temperature properties. In practice, the biggest challenge is to identify the types of interactions which are most important for a given alloy out of the many possibilities. We describe a genetic algorithm which automates this …

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Direct Enumeration Of Alloy Configurations For Electronic Structural Properties, Gus L. W. Hart, Peter A. Graf, Kwiseon Kim, Wesley B. Jones Oct 2005

Direct Enumeration Of Alloy Configurations For Electronic Structural Properties, Gus L. W. Hart, Peter A. Graf, Kwiseon Kim, Wesley B. Jones

Faculty Publications

We present and apply an approach to directly enumerate the band gaps and effective masses of all possible zinc blende-based alloy configurations whose unit cell contains up to a specified number of atoms. This method allows us to map the space of band gaps and effective masses versus alloy composition and atomic configuration. We demonstrate that a large number of band gaps and effective masses are available. We also discuss convergence of the method with respect to unit cell size and the combined optimization of band gap and effective mass for AlGaAs and GaInP semiconductor alloys.

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Specific Heat And Thermodynamic Properties Of Metallic Systems: Instrumentation And Analysis, Brian E. Lang Oct 2005

Specific Heat And Thermodynamic Properties Of Metallic Systems: Instrumentation And Analysis, Brian E. Lang

Theses and Dissertations

A small-scale adiabatic calorimeter has been constructed as part of a larger project to study nano-particles and to facilitate specific heat measurements on samples where it is difficult to obtain enough material to run on the current large-scale adiabatic apparatus. This calorimeter is designed to measure sample sizes of less than 0.8 cc over a temperature range from 13 K to 350 K. Specific heat results on copper, sapphire, and benzoic acid show the accuracy of the measurements to be better than ±0.4% for temperatures higher than 50 K. The reproducibility of these measurements is generally better than ±0.25%. Experimental …

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Phylogenetic Analysis Of Large Sequence Data Sets, Hyrum Carroll, Mark J. Clement, Keith Crandall, Quinn O. Snell Oct 2005

Phylogenetic Analysis Of Large Sequence Data Sets, Hyrum Carroll, Mark J. Clement, Keith Crandall, Quinn O. Snell

Faculty Publications

Phylogenetic analysis is an integral part of biological research. As the number of sequenced genomes increases, available data sets are growing in number and size. Several algorithms have been proposed to handle these larger data sets. A family of algorithms known as disc covering methods (DCMs), have been selected by the NSF funded CIPRes project to boost the performance of existing phylogenetic algorithms. Recursive Iterative Disc Covering Method 3 (Rec-I-DCM3), recursively decomposes the guide tree into subtrees, executing a phylogenetic search on the subtree and merging the subtrees, for a set number of iterations. This paper presents a detailed analysis …

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Rate-Adaptive Runlength Limited Encoding For High-Speed Infrared Communication, James Cyril Funk Sep 2005

Rate-Adaptive Runlength Limited Encoding For High-Speed Infrared Communication, James Cyril Funk

Theses and Dissertations

My thesis will demonstrate that Rate Adaptive Runlength Limited encoding (RA-RLL) achieves high data rates with acceptable error rate over a wide range of signal distortion/attenuation, and background noise. RA-RLL has performance superior to other infrared modulation schemes in terms of bandwidth efficiency, duty cycle control, and synchronization frequency. Rate adaptive techniques allow for quick convergence of RA-RLL parameters to acceptable values. RA-RLL may be feasibly implemented on systems with non-ideal timing and digital synchronization.

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