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Articles 2221 - 2250 of 2906

Full-Text Articles in Physical Sciences and Mathematics

An Acyl Radical Cascade Model For The Total Synthesis Of Lyconadin A, Seth W. Grant Sep 2005

An Acyl Radical Cascade Model For The Total Synthesis Of Lyconadin A, Seth W. Grant

Theses and Dissertations

Lyconadin A (1) is a structurally unique Lycopodium alkaloid with antitumor properties, isolated from the club moss Lycopodium complanatum. We are developing a synthetic route to 1 based on a novel 7-exo-trig/6-exo-trig acyl radical cascade cyclization. The synthesis of model acyl radical cascade precursor 23 will be presented. Key features of this synthesis include the suppression of competing elimination during the alkylation of a hindered phenethyl bromide and the use of a lactone as a precursor to a compound bearing two differentially protected primary alcohols. An account of our studies on the model acyl radical cascade cyclization (23 to 24 …

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Studies In The Dynamics Of Economic Systems, Christophe G. Giraud-Carrier, Kevin Seppi, Nghia Tran, Sean C. Warnick, W. Samuel Weyerman, R. Johnson Aug 2005

Studies In The Dynamics Of Economic Systems, Christophe G. Giraud-Carrier, Kevin Seppi, Nghia Tran, Sean C. Warnick, W. Samuel Weyerman, R. Johnson

Faculty Publications

This paper demonstrates the utility of systems and control theory in the analysis of economic systems. Two applications demonstrate how the analysis of simple dynamic models sheds light on important practical problems. The first problem considers the design of a retail laboratory, where the small gain theorem enables the falsification of pricing policies. The second problem explores industrial organization using the equilibria of profit-maximizing dynamics to quantify the percentage of a firm’s profits due strictly to the cooperative effects among its products. This ”Value of Cooperation” suggests an important measure for both organizational and antitrust applications.

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Effect Of Melatonin And Dopamine In Site Specific Phosphorylation Of Phosducin In Intact Retina, Arinzechukwu Okere Nkemdirim Aug 2005

Effect Of Melatonin And Dopamine In Site Specific Phosphorylation Of Phosducin In Intact Retina, Arinzechukwu Okere Nkemdirim

Theses and Dissertations

Phosducin (Pdc) is a 28 kDa binding partner for the G protein beta gamma subunit dimer (G-beta-gamma) found abundantly in the photoreceptor cells of the retina and pineal gland. In the retina, light-dependent changes in cAMP and Ca2+ control the phosphorylation of Pdc at serine 73 and 54, respectively, which in turn controls the binding of Pdc to G protein beta gamma subunit dimer . G protein beta gamma subunit dimer binding has been proposed to facilitate light-driven transport of G protein beta gamma subunit dimer from the site of phototransduction in the outer segment of the photoreceptor cell to …

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Challenging Policies That Do Not Play Fair: A Credential Relevancy Framework Using Trust Negotiation Ontologies, Travis S. Leithead Aug 2005

Challenging Policies That Do Not Play Fair: A Credential Relevancy Framework Using Trust Negotiation Ontologies, Travis S. Leithead

Theses and Dissertations

This thesis challenges the assumption that policies will "play fair" within trust negotiation. Policies that do not "play fair" contain requirements for authentication that are misleading, irrelevant, and/or incorrect, based on the current transaction context. To detect these unfair policies, trust negotiation ontologies provide the context to determine the relevancy of a given credential set for a particular negotiation. We propose a credential relevancy framework for use in trust negotiation that utilizes ontologies to process the set of all available credentials C and produce a subset of credentials C' relevant to the context of a given negotiation. This credential relevancy …

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Dynamic Dead Variable Analysis, Micah S. Lewis Aug 2005

Dynamic Dead Variable Analysis, Micah S. Lewis

Theses and Dissertations

Dynamic dead variable analysis (DDVA) extends traditional static dead variable analysis (SDVA) in the context of model checking through the use of run-time information. The analysis is run multiple times during the course of model checking to create a more precise set of dead variables. The DDVA is evaluated based on the amount of memory used to complete model checking relative to SDVA while considering the extra overhead required to implement DDVA. On several models with a complex control flow graph, DDVA reduces the amount of memory needed by 38-88MB compared to SDVA with a cost of 36 bytes of …

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Using Box-Scores To Determine A Position's Contribution To Winning Basketball Games, Garritt L. Page Aug 2005

Using Box-Scores To Determine A Position's Contribution To Winning Basketball Games, Garritt L. Page

Theses and Dissertations

Basketball is a sport that has become increasingly popular world-wide. At the professional level it is a game in which each of the five positions has a specific responsibility that requires unique skills. It seems likely that it would be valuable for coaches to know which skills for each position are most conducive to winning. Knowing which skills to develop for each position could help coaches optimize each player's ability by customizing practice to contain drills that develop the most important skills for each position that would in turn improve the team's overall ability. Through the use of Bayesian hierarchical …

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An Acoustical Analysis Of Domes Coupled To Rooms, With Special Application To The Darussholah Mosque, In East Java, Indonesia, Sentagi Sesotya Utami Aug 2005

An Acoustical Analysis Of Domes Coupled To Rooms, With Special Application To The Darussholah Mosque, In East Java, Indonesia, Sentagi Sesotya Utami

Theses and Dissertations

Concave surfaces are often considered to be detrimental or precarious in room acoustics, especially because of the impact they have on the distribution of sound energy. However, it is often difficult to avoid such surfaces in buildings with specific architectural functions. A primary example of this involves mosques, which are sacred places of worship for Muslims. In keeping with the Islamic architectural style, most mosques incorporate a symbolic centralized domed ceiling as part of their room structures. These domes are open on the bottom and coupled to the acoustic spaces below. In many cases, the lower spaces may be idealized …

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Estimating The Discrepancy Between Computer Model Data And Field Data: Modeling Techniques For Deterministic And Stochastic Computer Simulators, Emily Joy Dastrup Aug 2005

Estimating The Discrepancy Between Computer Model Data And Field Data: Modeling Techniques For Deterministic And Stochastic Computer Simulators, Emily Joy Dastrup

Theses and Dissertations

Computer models have become useful research tools in many disciplines. In many cases a researcher has access to data from a computer simulator and from a physical system. This research discusses Bayesian models that allow for the estimation of the discrepancy between the two data sources. We fit two models to data in the field of electrical engineering. Using this data we illustrate ways of modeling both a deterministic and a stochastic simulator when specific parametric assumptions can be made about the discrepancy term.

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Task Similarity Measures For Transfer In Reinforcement Learning Task Libraries, James Carroll, Kevin Seppi Aug 2005

Task Similarity Measures For Transfer In Reinforcement Learning Task Libraries, James Carroll, Kevin Seppi

Faculty Publications

Recent research in task transfer and task clustering has necessitated the need for task similarity measures in reinforcement learning. Determining task similarity is necessary for selective transfer where only information from relevant tasks and portions of a task are transferred. Which task similarity measure to use is not immediately obvious. It can be shown that no single task similarity measure is uniformly superior. The optimal task similarity measure is dependent upon the task transfer method being employed. We define similarity in terms of tasks, and propose several possible task similarity measures, dT, dp, dQ, and dR which are based on …

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Piecing Together The Triassic/Jurassic Stratigraphy Along The South Flank Of The Uinta Mountains, Northeast Utah: A Stratigraphic Analysis Of The Bell Springs Member Of The Nugget Sandstone, Paul H. Jensen Jr. Aug 2005

Piecing Together The Triassic/Jurassic Stratigraphy Along The South Flank Of The Uinta Mountains, Northeast Utah: A Stratigraphic Analysis Of The Bell Springs Member Of The Nugget Sandstone, Paul H. Jensen Jr.

Theses and Dissertations

Nomenclature for the Upper Triassic and Lower Jurassic strata along the south flank of the Uinta Mountains has been somewhat confusing because of the position of the study area between southern Wyoming, where one set of names is used, and central/southern Utah where a different set of formation names is used. The Nugget Sandstone or Glen Canyon Sandstone of the eastern Uinta Mountains overlies the Upper Triassic Popo Agie or Chinle Formation. The nature of the contact between these two formations is unclear both in stratigraphic location and conformability. The Chinle Formation consists, in ascending order, of the Gartra Member, …

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Edge Inference For Image Interpolation, Bryan S. Morse, Neil Toronto, Dan A. Ventura Aug 2005

Edge Inference For Image Interpolation, Bryan S. Morse, Neil Toronto, Dan A. Ventura

Faculty Publications

Image interpolation algorithms try to fit a function to a matrix of samples in a "natural-looking" way. This paper presents edge inference, an algorithm that does this by mixing neural network regression with standard image interpolation techniques. Results on gray level images are presented, and it is demonstrated that edge inference is capable of producing sharp, natural-looking results. A technique for reintroducing noise is given, and it is shown that, with noise added using a bicubic interpolant, edge inference can be regarded as a generalization of bicubic interpolation. Extension into RGB color space and additional applications of the algorithm are …

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Performance Of Aic-Selected Spatial Covariance Structures For Fmri Data, David A. Stromberg Jul 2005

Performance Of Aic-Selected Spatial Covariance Structures For Fmri Data, David A. Stromberg

Theses and Dissertations

FMRI datasets allow scientists to assess functionality of the brain by measuring the response of blood flow to a stimulus. Since the responses from neighboring locations within the brain are correlated, simple linear models that assume independence of measurements across locations are inadequate. Mixed models can be used to model the spatial correlation between observations, however selecting the correct covariance structure is difficult. Information criteria, such as AIC are often used to choose among covariance structures. Once the covariance structure is selected, significance tests can be used to determine if a region of interest within the brain is significantly active. …

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A Modified Poisson–Boltzmann Analysis Of The Capacitance Behavior Of The Electric Double Layer At Low Temperatures, Douglas Henderson, L. B. Bhuiyan, C. W. Outhwaite Jul 2005

A Modified Poisson–Boltzmann Analysis Of The Capacitance Behavior Of The Electric Double Layer At Low Temperatures, Douglas Henderson, L. B. Bhuiyan, C. W. Outhwaite

Faculty Publications

The modified Poisson–Boltzmann theory is used to analyze the anomalous behavior of the electric double layer capacitance for small surface charge at low temperatures and densities. Good agreement is found with simulation and recent density-functional theory results. Negative adsorption is also found in line with theory and simulation. An unsatisfactory feature is the relatively poor structure in this region due to the inherent approximations in the theory. This feature is unimportant in relation to the capacitance results but has implications when calculating adsorption properties.

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Detecting Similar Html Documents Using A Sentence-Based Copy Detection Approach, Rajiv Yerra Jul 2005

Detecting Similar Html Documents Using A Sentence-Based Copy Detection Approach, Rajiv Yerra

Theses and Dissertations

Web documents that are either partially or completely duplicated in content are easily found on the Internet these days. Not only these documents create redundant information on the Web, which take longer to filter unique information and cause additional storage space, but also they degrade the efficiency of Web information retrieval. In this thesis, we present a new approach for detecting similar (HTML)Web documents and evaluate its performance. To detect similar documents, we first apply our sentence-based copy detection approach to determine whether sentences in any two documents should be treated as the same or different according to the degrees …

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Constraint-Based Interpolation, Daniel David Goggins Jul 2005

Constraint-Based Interpolation, Daniel David Goggins

Theses and Dissertations

Image reconstruction is the process of converting a sampled image into a continuous one prior to transformation and resampling. This reconstruction can be more accurate if two things are known: the process by which the sampled image was obtained and the general characteristics of the original image. We present a new reconstruction algorithm known as Constraint-Based Interpolation, which estimates the sampling functions found in cameras and analyzes properties of real world images in order to produce quality real-world image magnifications. To accomplish this, Constraint-Based Interpolation uses a sensor model that pushes the pixels in an interpolation to more closely match …

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Hard-Sphere Radial Distribution Function Again, Andrij Trokhymchuk, Douglas Henderson, Ivo Nezbeda, Jan Jirsak Jul 2005

Hard-Sphere Radial Distribution Function Again, Andrij Trokhymchuk, Douglas Henderson, Ivo Nezbeda, Jan Jirsak

Faculty Publications

A theoretically based closed-form analytical equation for the radial distribution function, g(r), of a fluid of hard spheres is presented and used to obtain an accurate analytic representation. The method makes use of an analytic expression for the short- and long-range behaviors of g(r), both obtained from the Percus-Yevick equation, in combination with the thermodynamic consistency constraint. Physical arguments then leave only three parameters in the equation of g(r) that are to be solved numerically, whereas all remaining ones are taken from the analytical solution of the Percus-Yevick equation.

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Cache Characterization And Performance Studies Using Locality Surfaces, Elizabeth Schreiner Sorenson Jul 2005

Cache Characterization And Performance Studies Using Locality Surfaces, Elizabeth Schreiner Sorenson

Theses and Dissertations

Today's processors commonly use caches to help overcome the disparity between processor and main memory speeds. Due to the principle of locality, most of the processor's requests for data are satisfied by the fast cache memory, resulting in a signficant performance improvement. Methods for evaluating workloads and caches in terms of locality are valuable for cache design. In this dissertation, we present a locality surface which displays both temporal and spatial locality on one three-dimensional graph. We provide a solid, mathematical description of locality data and equations for visualization. We then use the locality surface to examine the locality of …

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Development Of A Model For The Kinetics And Mechanism Of Nitrogenase, Phillip E. Wilson Jul 2005

Development Of A Model For The Kinetics And Mechanism Of Nitrogenase, Phillip E. Wilson

Theses and Dissertations

Nitrogenase has a central role in the global nitrogen cycle as the enzyme that catalyzes the reduction of atmospheric N2 to NH3. Fixed nitrogen is generally limiting in the environment and in agriculture, so nitrogenase has received much attention as an alternative to nitrogen fertilizers. Characterizing the mechanism of nitrogenase is the goal of this work. The molybdenum nitrogenase enzyme system is comprised of the MoFe protein and the Fe protein. Interactions between these proteins and nucleotides are crucial to catalysis. An important approach to characterize these interactions is to correlate the kinetics of nitrogenase catalysis to a mechanism based …

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Angiotensin Ii-Mediated Regulation Of The Human Angiotensin Ii Type 1 Receptor Gene, Xylophone Vijai Aasee Victor Jul 2005

Angiotensin Ii-Mediated Regulation Of The Human Angiotensin Ii Type 1 Receptor Gene, Xylophone Vijai Aasee Victor

Theses and Dissertations

The physiological responses of angiotensin II (Ang II) are mediated across the cell membrane through the angiotensin II type 1 receptor (AT1R), a heptahelical membrane protein coupled to trimeric G-proteins on the cytosolic side. AT1R on binding its ligand, Ang II, leads to downregulation of cell-surface receptor and also its mRNA. We have investigated whether the 3'- and 5'-untranslated regions of the human AT1R mRNA mediate the degradation of hAT1R mRNA by post-transcriptional mechanisms in human adrenocortical carcinoma cell line (H295R cells). Protein kinase C (PKC) activator, phorbol-12-myristate-13-acetate (PMA), showed that the downregulation of hAT1R mRNA is mediated by the …

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Elevation, Longitudinal Profile, And Schmidt Hammer Analysis Of Strath Terraces Through Capitol Reef National Park, Utah: Bedrock Channel Response To Climate Forcing?, James L. Eddleman Jul 2005

Elevation, Longitudinal Profile, And Schmidt Hammer Analysis Of Strath Terraces Through Capitol Reef National Park, Utah: Bedrock Channel Response To Climate Forcing?, James L. Eddleman

Theses and Dissertations

Elevation, longitudinal profile, and Schmidt hammer data indicate that strath terraces (specifically the lower elevation terraces) mapped in the Fremont River drainage of Capitol Reef National Park are correlative to the terraces of the smaller Pleasant Creek drainage located approximately ten miles to the south. This correlation suggests that drainage development in this area of the Colorado Plateau was strongly dependent upon a regional-scale forcing mechanism (e.g. climate) rather than strictly independent basin-scale processes. Elevations of mapped strath terraces and their associated black volcanic boulder deposits were calculated from geologic maps, Digital Elevation Models (DEM), and Digital Orthophoto Quadrangles of …

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Effects Of Hurricane Fault Architecture On Groundwater Flow In The Timpoweap Canyon Of Southwestern, Utah, Sarah J. Dutson Jul 2005

Effects Of Hurricane Fault Architecture On Groundwater Flow In The Timpoweap Canyon Of Southwestern, Utah, Sarah J. Dutson

Theses and Dissertations

Hydrogeologically important features of fault zones include undamaged country rock, the damage zone, and the core zone. Fault cores generally have low porosity and permeability, and often act as a barrier to groundwater flow. The damage zone, by contrast, consists of small faults and fracture networks, which can act as conduits. Timpoweap Canyon near Hurricane, Utah has superb exposures of the fault core and damage zone of the Hurricane Fault. Also within the canyon, springs discharge from the damage zone into the Virgin River, providing an ideal natural laboratory for the study of groundwater discharge from a fault zone. The …

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Establishing Public Confidence In The Viability Of Fingerprint Biometric Technology, Nathan Alan Green Jul 2005

Establishing Public Confidence In The Viability Of Fingerprint Biometric Technology, Nathan Alan Green

Theses and Dissertations

The most common personal authentication techniques used for identity management employ a secret PIN or password that must be remembered. The challenge, for a given user, is that a multitude of such codes must be recalled over the course of the day for transactions involving distinct computer applications. Password mania prevails. Fingerprint biometric technology is an ideal alternate solution to this password recall problem. In spite of their availability for nearly thirty years, fingerprint biometric systems still remain uncommon in public sectors of industry such as education, government, and technology. Technology has improved sufficiently that false acceptance and rejection rates …

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A Mathematical Model Of Adhesion Interactions Between Living Cells, Casey P. Johnson Jul 2005

A Mathematical Model Of Adhesion Interactions Between Living Cells, Casey P. Johnson

Theses and Dissertations

This thesis presents a simple force-based model of moving and interacting cells that incorporates a realistic description of cell adhesion and applies it to a system of spherical cells. In addition, several results in matrix theory are proved with the end of showing that the equations produced by the model uniquely determine the motion of the system or cells.

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Representations For Understanding The Stern-Gerlach Effect, Jared R. Stenson Jul 2005

Representations For Understanding The Stern-Gerlach Effect, Jared R. Stenson

Theses and Dissertations

The traditional explanation of the Stern-Gerlach effect carries with it several very subtle assumptions and approximations. We point out the degree to which this fact has affected the way we practice and interpret modern physics. In order to gain a more complete understanding of the Stern-Gerlach effect beyond the standard approximations and assumptions it typically carries, we introduce the inhomogeneous Stern-Gerlach effect in which the strong uniform field component is removed. This change allows us to easily identify precession as a critical concept. It also provides us with a means by which to study precession and analyze it critically. By …

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Black Spaghetti: A Numerical Model Of Gravitational Collapse In 4 + 1 Spacetime, Michael P. Christenson Jul 2005

Black Spaghetti: A Numerical Model Of Gravitational Collapse In 4 + 1 Spacetime, Michael P. Christenson

Theses and Dissertations

We investigate spherically-symmetric gravitational collapse in the presence of a single "large" extra dimension through the use of analytical and numerical techniques. This has bearing on higher-dimensional ideas concerning hypothetical objects called "black strings," or black holes extending into an extra circular dimension, which dimension we hereinafter label zeta. These putative objects were first seriously considered as elements of string theory but have relevance in simpler, higher-dimensional generalization of Einstein's general relativity. We assume a universe topologically consisting of a two-dimensional Lorentzian manifold crossed with the sphere, crossed again with the circle. We model the formation of a uniform black …

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Accelerated Ray Traced Animations Exploiting Temporal Coherence, Darwin Tarry Baines Jul 2005

Accelerated Ray Traced Animations Exploiting Temporal Coherence, Darwin Tarry Baines

Theses and Dissertations

Ray tracing is a well-know technique for producing realistic graphics. However, the time necessary to generate images is unacceptably long. When producing the many frames that are necessary for animations, the time is magnified. Many methods have been proposed to reduce the calculations necessary in ray tracing. Much of the effort has attempted to reduce the number of rays cast or to reduce the number of intersection calculations. Both of these techniques exploit spatial coherence. These acceleration techniques are expanded not only to exploit spatial coherence but also to exploit temporal coherence in order to reduce calculations by treating animation …

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An Improved Flexible Neutron Detector For Powder Diffraction Experiments, Thomas Kevin Mcknight Jul 2005

An Improved Flexible Neutron Detector For Powder Diffraction Experiments, Thomas Kevin Mcknight

Theses and Dissertations

Large amounts of money are being applied to the construction of the next generation of spallation sources for neutron scattering. Neutron powder diffraction instruments will be an important element of these facilities and the incorporation of detectors into these instruments with a high neutron capture efficiency is desirable. A new detector design named the Flexible Embedded Fiber Detector (FEFD) has been developed and tested for this thesis. This detector is based on wavelength shifting fibers embedded in a zinc-sulfide lithium-fluoride based scintillator. The virtue of this design is that the detecting surface can be curved around the Debye-Scherrer rings. This …

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Novel Neutron Detector For N-N Scattering Length Measurement, Eva Wilcox Jul 2005

Novel Neutron Detector For N-N Scattering Length Measurement, Eva Wilcox

Theses and Dissertations

The neutron-neutron (n-n) scattering length is a fundamental parameter in nuclear physics; however, measurements are plagued with large uncertainties caused by neutron detector cross talk. Many experimentalists also rely upon computer code to calibrate their neutron detectors. Experiments give one of two different numbers but there is still no adequate explanation for this discrepancy. We have developed a new neutron detector expressly for the purpose of improving the n-n scattering length measurement. It offers two important advantages: 1) minimal cross talk and 2) high counting efficiency. We calibrated the detector from 1 MeV to 6 MeV at 1 MeV increments. …

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Task Localization, Similarity, And Transfer; Towards A Reinforcement Learning Task Library System, James Lamond Carroll Jul 2005

Task Localization, Similarity, And Transfer; Towards A Reinforcement Learning Task Library System, James Lamond Carroll

Theses and Dissertations

This thesis develops methods of task localization, task similarity discovery, and task transfer for eventual use in a reinforcement learning task library system, which can effectively “learn to learn,” improving its performance as it encounters various tasks over the lifetime of the learning system.

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Suitability Of The Nist Shop Data Model As A Neutral File Format For Simulation, Gregory Brent Harward Jul 2005

Suitability Of The Nist Shop Data Model As A Neutral File Format For Simulation, Gregory Brent Harward

Theses and Dissertations

Due to the successful application in internet related fields, Extensible Markup Language (XML) and its related technologies are being explored as a revolutionary software file format technology used to provide increased interoperability in the discrete-event simulation (DES) arena. The National Institute of Standards and Technology (NIST) has developed an XML-based information model (XSD) called the Shop Data Model (SDM), which is used to describe the contents of a neutral file format (NFF) that is being promoted as a means to make manufacturing simulation technology more accessible to a larger group of potential customers. Using a two step process, this thesis …

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