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Brigham Young University

Faculty Publications

1988

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

A Parallel-Processing Subsystem For Rapid 3-D Interpolation Of Ct Images, William A. Barrett, Stephen J. Allan, Scott R. Cannon Sep 1988

A Parallel-Processing Subsystem For Rapid 3-D Interpolation Of Ct Images, William A. Barrett, Stephen J. Allan, Scott R. Cannon

Faculty Publications

An inexpensive parallel-processing subsystem for the rapid interpolation of CT image planes is demonstrated with a variety of node topologies. The subsystem is based on a tree network of INMOS T414 Transputer processors and is hosted by an AT-based image workstation. The subsystem accepts a stack of eight arbitrarily-spaced 256 x 256 image planes from the host. Subsystem output to the host consists of a stack of 32 scaled and evenly-spaced image planes (256 x 256 x 32 with cubic voxels). Benchmark execution times ranged from 12.3 seconds for three nodes to 5.8 seconds for eight nodes.

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Dynamic Display And Quantitative Analysis Of Three-Dimensional Left Ventricular Pathology, William A. Barrett, Jayaram K. Udupa Sep 1988

Dynamic Display And Quantitative Analysis Of Three-Dimensional Left Ventricular Pathology, William A. Barrett, Jayaram K. Udupa

Faculty Publications

Techniques have been developed for automated extraction and dynamic interactive display of three-dimensional (3D) left ventricular (LV) surface anatomy from Cine CT images using a PC-based image display architecture. Images of both endocardial and myocardial surface anatomy are generated from multiple views at multiple time instances to demonstrate various LV pathologies including apical akinesis, apical and posterior aneurysms, LV Failure, IHSS, and a left atrial myxoma. Surface generation requires interpolation between scans, surface tracking, and rendering. Generation of 60 views corresponding to a single time instance requires approximately 15 minutes. LV dimensions are measured between two or more surface points …

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Quasilinear Evolution Equations In Nonclassical Diffusion, Kenneth Kuttler, Elias Aifantis Jan 1988

Quasilinear Evolution Equations In Nonclassical Diffusion, Kenneth Kuttler, Elias Aifantis

Faculty Publications

After describing the motivation leading to some nonclassical diffusion equations, we formulate a general abstract nonlinear evolution equation and establish existence of solutions. Then we return to the original equation and discuss particular initial-boundary value problems.

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Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele Jan 1988

Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele

Faculty Publications

Using a formulation of quantum electrodynamics that is not second quantized, but rather based on self-fields, we compute the anomalous magnetic moment of the electron to first order in the fine structure constant α. In the nonrelativistic (NR) case and in the dipole approximation, our result is ae≡(g—2)/2=(4Λ/3m)(α/2π), where Λ is a positive photon energy cutoff and m the electron mass. A reasonable choice of cutoff, Λ/m=¾, yields the correct sign and magnitude for g—2 namely, ae=+α/2π. . In our formulation the sign of a3 is correctly positive, …

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Digital Neural Networks, Tony R. Martinez Jan 1988

Digital Neural Networks, Tony R. Martinez

Faculty Publications

Demands for applications requiring massive parallelism in symbolic environments have given rebirth to research in models labeled as neural networks. These models are made up of many simple nodes which are highly interconnected such that computation takes place as data flows amongst the nodes of the network. To present, most models have proposed nodes based on simple analog functions, where inputs are multiplied by weights and summed, the total then optionally being transformed by an arbitrary function at the node. Learning in these systems is accomplished by adjusting the weights on the input lines. This paper discusses the use of …

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Comparison Of Effective Medium Procedures For Optical Modeling Of Laminar Structures, David D. Allred, Robert F. Edgerton Jan 1988

Comparison Of Effective Medium Procedures For Optical Modeling Of Laminar Structures, David D. Allred, Robert F. Edgerton

Faculty Publications

This study addresses the question, "How can the optical properties of matter in ultrathin amorphous nonmetallic films in multilayers best be determined from reflectance (R) and transmission (T) measurements?" A blue shift in the band gap of plasma CVD a-Si:H/a-SiNx:H multilayers was reported several years ago. It was suggested that the shift in the band gap, Eg, Relative to bulk a-Si:H as given by the Tauç plot was due to quantum confinement effects. The purpose of this study is to evaluate the usefulness of various effective media theories (EMT) for determining the optical constants of materials in a multilayer and …

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Nonlocal Symmetries And Backlund Transformations For The Self-Dual Yang-Mills System, C. J. Papachristou, Kent B. Harrison Jan 1988

Nonlocal Symmetries And Backlund Transformations For The Self-Dual Yang-Mills System, C. J. Papachristou, Kent B. Harrison

Faculty Publications

The observation is made that generalized evolutionary isovectors of the self-dual Yang–Mills equation, obtained by "verticalization'' of the geometrical isovectors derived in a previous paper [J. Math. Phys. 28, 1261 (1987)], generate Bäcklund transformations for the self-dual system. In particular, new Bäcklund transformations are obtained by "verticalizing'' the generators of point transformations on the solution manifold. A geometric ansatz for the derivation of such (generally nonlocal) symmetries is proposed.

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