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Interpolation and Approximation

Description: In this paper, there are three chapters. The first chapter discusses interpolation. Here a theorem about the uniqueness of the solution to the general interpolation problem is proven. Then the problem of how to represent this unique solution is discussed. Finally, the error involved in the interpolation and the convergence of the interpolation process is developed. In the second chapter a theorem about the uniform approximation to continuous functions is proven. Then the best approximation and… more
Date: May 1977
Creator: Lal, Ram
Partner: UNT Libraries
open access

A 3D Contact Smoothing Method

Description: Smoothing of contact surfaces can be used to eliminate the chatter typically seen with node on facet contact and give a better representation of the actual contact surface. The latter affect is well demonstrated for problems with interference fits. In this work we present two methods for the smoothing of contact surfaces for 3D finite element contact. In the first method, we employ Gregory patches to smooth the faceted surface in a node on facet implementation. In the second method, we employ a… more
Date: May 2, 2002
Creator: Puso, M. A. & Laursen, T. A.
Partner: UNT Libraries Government Documents Department
open access

General MoM Solutions for Large Arrays

Description: This paper focuses on a numerical procedure that addresses the difficulties of dealing with large, finite arrays while preserving the generality and robustness of full-wave methods. We present a fast method based on approximating interactions between sufficiently separated array elements via a relatively coarse interpolation of the Green's function on a uniform grid commensurate with the array's periodicity. The interaction between the basis and testing functions is reduced to a three-stage pro… more
Date: July 22, 2003
Creator: Fasenfest, B; Capolino, F; Wilton, D R; Jackson, D R & Champagne, N
Partner: UNT Libraries Government Documents Department
open access

A New Stabilized Nodal Integration Approach

Description: A new stabilized nodal integration scheme is proposed and implemented. In this work, focus is on the natural neighbor meshless interpolation schemes. The approach is a modification of the stabilized conforming nodal integration (SCNI) scheme and is shown to perform well in several benchmark problems.
Date: February 8, 2006
Creator: Puso, M; Zywicz, E & Chen, J S
Partner: UNT Libraries Government Documents Department
open access

Interpolation of probability densities in ENDF and ENDL

Description: Suppose that we are given two probability densities p{sub 0}(E{prime}) and p{sub 1}(E{prime}) for the energy E{prime} of an outgoing particle, p{sub 0}(E{prime}) corresponding to energy E{sub 0} of the incident particle and p{sub 1}(E{prime}) corresponding to incident energy E{sub 1}. If E{sub 0} < E{sub 1}, the problem is how to define p{sub {alpha}}(E{prime}) for intermediate incident energies E{sub {alpha}} = (1 - {alpha})E{sub 0} + {alpha}E{sub 1} with 0 < {alpha} < 1. In this note… more
Date: January 27, 2006
Creator: Hedstrom, G
Partner: UNT Libraries Government Documents Department
open access

Symplectic Interpolation.

Description: It is important to have symplectic maps for the various electromagnetic elements in an accelerator ring. For some tracking problems we must consider elements which evolve during a ramp. Rather than performing a computationally intensive numerical integration for every turn, it should be possible to integrate the trajectory for a few sets of parameters, and then interpolate the transport map as a function of one or more parameters, such as energy. We present two methods for interpolation of symp… more
Date: June 23, 2006
Creator: MacKay, W. W. & Luccio, A. U.
Partner: UNT Libraries Government Documents Department
open access

Viscosity of Aqueous Sodium Chloride Solutions From 0 - 150° C

Description: A critical evaluation of data on the viscosity of aqueous sodium chloride solutions is presented. The literature was screened through October 1977, and a databank of evaluated data was established. Viscosity values were converted when necessary to units of centigrade, centipoise and molal concentration. The data were correlated with the aid of an empirical equation to facilitate interpolation and computer calculations. The result of the evaluation includes a table containing smoothed values for… more
Date: October 1, 1977
Creator: Ozbek, H.; Fair, J. A. & Phillips, S. L.
Partner: UNT Libraries Government Documents Department
open access

Spectral Interpolation on 3 x 3 Stencils for Prediction and Compression

Description: Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, … more
Date: June 25, 2007
Creator: Ibarria, L; Lindstrom, P & Rossignac, J
Partner: UNT Libraries Government Documents Department
open access

Distance-Two Interpolation for Parallel Algebraic Multigrid

Description: Algebraic multigrid (AMG) is one of the most efficient and scalable parallel algorithms for solving sparse linear systems on unstructured grids. However, for large three-dimensional problems, the coarse grids that are normally used in AMG often lead to growing complexity in terms of memory use and execution time per AMG V-cycle. Sparser coarse grids, such as those obtained by the Parallel Modified Independent Set coarsening algorithm (PMIS) [7], remedy this complexity growth, but lead to non-sc… more
Date: May 8, 2007
Creator: De Sterck, H; Falgout, R; Nolting, J & Yang, U M
Partner: UNT Libraries Government Documents Department
open access

EVIDENCE FOR THE ITINERANT ELECTRON MODEL OF FERROMAGNETISM AND FOR SURFACE PHOTOEMISSION FROM ANGLE-RESOLVED PHOTOEMISSION STUDIES OF IRON

Description: Angle-resolved HeI photoemission spectra of Fe(001) are reported and interpreted within the framework of a direct transition model using Callaway's ferromagnetic band structure. The generally good agreement between predicted and experimental peak positions is taken to be strong support for the itinerant electron theory of ferromagnetism. Spectra taken with nearly grazing incidence p-polarized light emphasize the one-dimensional density of states peaks, supporting Kliewer's theoretical predictio… more
Date: October 1, 1977
Creator: Kevan, S.D.; Wehner, P.S. & Shirley, D.A.
Partner: UNT Libraries Government Documents Department
open access

Spatially Interpolated Nonlinear Anodization in Synthetic Aperture Radar Imagery

Description: Spatially Interpolated Nonlinear Anodization in Synthetic Aperture Original formulation of spatially variant anodization for complex synthetic aperture radar (SAR) imagery oversampled at twice the Nyquist rate (2.OX). Here we report a spatially interpolating, noninteger-oversampled SVA sidelobe. The pixel's apparent IPR location is assessed by comparing its value to the sum of its value plus weighted comparable for exact interpolation. However, exact interpolation implies an ideal sine interpol… more
Date: June 29, 1999
Creator: Eichel, Paul H.; Jakowatz, Charles V., Jr. & Yocky, David A.
Partner: UNT Libraries Government Documents Department
open access

List mode reconstruction for PET with motion compensation: A simulation study

Description: Motion artifacts can be a significant factor that limits the image quality in high-resolution PET. Surveillance systems have been developed to track the movements of the subject during a scan. Development of reconstruction algorithms that are able to compensate for the subject motion will increase the potential of PET. In this paper we present a list mode likelihood reconstruction algorithm with the ability of motion compensation. The subject motion is explicitly modeled in the likelihood funct… more
Date: July 1, 2002
Creator: Qi, Jinyi & Huesman, Ronald H.
Partner: UNT Libraries Government Documents Department
open access

Experiences with BoomerAMG:: A Parallel Algebraic Multigrid Solver and Preconditioner for Large Linear Systems

Description: Algebraic multigrid (AMG) is an attractive choice for solving large linear systems {Lambda}x = b on unstructured grids. While AMG is applicable as a solver for a variety of problems, its robustness may be enhanced by using it as a preconditioner for Krylov solvers, such as GMRES. The sheer size of modern problems, hundreds of millions or billions of unknowns, dictates the use of massively parallel computers. AMG consists of two phases: the setup phase, in which smaller and smaller linear system… more
Date: February 22, 2000
Creator: Hensor, V E & Yang, U M
Partner: UNT Libraries Government Documents Department
open access

List mode reconstruction for PET with motion compensation: A simulation study

Description: Motion artifacts can be a significant factor that limits the image quality in high-resolution PET. Surveillance systems have been developed to track the movements of the subject during a scan. Development of reconstruction algorithms that are able to compensate for the subject motion will increase the potential of PET. In this paper we present a list mode likelihood reconstruction algorithm with the ability of motion compensation. The subject moti is explicitly modeled in the likelihood functio… more
Date: July 3, 2002
Creator: Qi, Jinyi & Huesman, Ronald H.
Partner: UNT Libraries Government Documents Department
open access

Modeling Current-Voltage Curves Using Bilinear Interpolation: Preprint

Description: Current-voltage (I-V) curves for photovoltaic (PV) modules representing all PV technologies were modeled by bilinearly interpolating the I-V curves from a PV module's four reference I-V curves. The interpolation was performed first with respect to open-circuit voltage to account for PV module temperature, and second with respect to short-circuit current to account for irradiance. The modeled I-V curves compared closely with measured I-V curves for 26 PV modules located at the National Renewable… more
Date: August 1, 2004
Creator: Marion, B.; del Cueto, J. & Sekulic, B.
Partner: UNT Libraries Government Documents Department
open access

Final Report for "Analyzing and visualizing next generation climate data"

Description: The project "Analyzing and visualizing next generation climate data" adds block-structured (mosaic) grid support, parallel processing, and 2D/3D curvilinear interpolation to the open-source UV-CDAT climate data analysis tool. Block structured grid support complies to the Gridspec extension submitted to the Climate and Forecast metadata conventions. It contains two parts: aggregation of data spread over multiple mosaic tiles (M-SPEC) and aggregation of temporal data stored in different files (F-… more
Date: November 13, 2012
Creator: Pletzer, Alexander
Partner: UNT Libraries Government Documents Department
open access

ERA-40 SST and Sea Ice Concentration Data

Description: The lower boundary condition of sea surface temperature (SST) and sea-ice concentration (sic) is a critical forcing of the lower frequencies in multi-decadal global atmospheric reanalyses such as ERA-40. Partly in response to the ERA-40 project, new SST/sic data sets have been developed that are considerably improved over those available to the first-generation reanalyses. This paper documents the input SST/sic data sets and the processing that created the daily SST/sic specification for the ER… more
Date: August 27, 2001
Creator: Fiorino, M
Partner: UNT Libraries Government Documents Department
open access

LIP: The Livermore Interpolation Package, Version 1.3

Description: This report describes LIP, the Livermore Interpolation Package. Because LIP is a stand-alone version of the interpolation package in the Livermore Equation of State (LEOS) access library, the initials LIP alternatively stand for the ''LEOS Interpolation Package''. LIP was totally rewritten from the package described in [1]. In particular, the independent variables are now referred to as x and y, since the package need not be restricted to equation of state data, which uses variables {rho} (dens… more
Date: January 4, 2011
Creator: Fritsch, F N
Partner: UNT Libraries Government Documents Department
open access

LIP: The Livermore Interpolation Package, Version 1.4

Description: This report describes LIP, the Livermore Interpolation Package. Because LIP is a stand-alone version of the interpolation package in the Livermore Equation of State (LEOS) access library, the initials LIP alternatively stand for the 'LEOS Interpolation Package'. LIP was totally rewritten from the package described in [1]. In particular, the independent variables are now referred to as x and y, since the package need not be restricted to equation of state data, which uses variables {rho} (densit… more
Date: July 6, 2011
Creator: Fritsch, F N
Partner: UNT Libraries Government Documents Department
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