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COMP: a BASIC language nonlinear least-squares curve fitting program

Description: COMP is an interactive nonlinear least squares routine written in BASIC language and used to obtain estimates of parameters in nonlinear functions and to approximate their associated statistical errors. The program uses the linearizing (or Taylor Series) expansion of partial derivatives outlined in Draper and Smith, (1966, pp. 267 to 270). Therefore, partial derivatives must be supplied (as well as the function) by the user for any new models not currently contained in the programs. When a line… more
Date: November 1, 1977
Creator: Thomas, J. M.; Cochran, M. I.; Watson, C. R. & Eberhardt, L. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Stress analysis of MFTF-B getter system bellows. Final report

Description: The MFTF-B design includes a retractable getter system. Eight getter assemblies are planned (4 in each end plug). Electrically heated Ti wires are mounted on a telescoping insertion mechanism and, between machine shots (pulses), are extended into the chamber in the vicinity of inward-facing water-cooled magnet liners. During the shots, the sublimators must be withdrawn because they will intrude into plasma and diagnostic space. Each of the getter assemblies will be mounted on the exterior of th… more
Date: April 1, 1982
Creator: Tokarz, F. J.; Johnson, J. J.; Mukherjee, A. N. & Dalder, E. N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Physical simulations of cavity closure in a creeping material

Description: The finite element method has been used extensively to predict the creep closure of underground petroleum storage cavities in rock salt. Even though the numerical modeling requires many simplifying assumptions, the predictions have generally correlated with field data from instrumented wellheads, however, the field data are rather limited. To gain an insight into the behavior of three-dimensional arrays of cavities and to obtain a larger data base for the verification of analytical simulations … more
Date: September 1, 1985
Creator: Sutherland, H.J. & Preece, D.S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Relation between finite element methods and nodal methods in transport theory

Description: This paper examines the relationship between nodal methods and finite-element methods for solving the discrete-ordinates form of the transport equation in x-y geometry. Specifically, we will examine the relation of three finite-element schemes to the linear-linear (LL) and linear-nodal (LN) nodal schemes. The three finite-element schemes are the linear-continuous-diamond-difference (DD) scheme, the linear-discontinuous (LD) scheme, and the quadratic-discontinuous (QD) scheme. A brief derivation… more
Date: January 1, 1985
Creator: Walters, W. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Development of a computer program for reactor core thermal hydraulics: finite differencing in a 3-D staggered mesh suitable for irregular boundary applications

Description: A formulation utilizing a finite difference scheme for the direct numerical simulation of time varying two-phase flow problems in three space dimensions with irregular boundary geometry is presented. The formulation of such problems introduces a complicated set of coupled non-linear partial differential equations for the conservation of mass, momentum, energy, appropriate constitutive equations, and equations of state coupling the two phases. Discretization of the partial differential equations… more
Date: unknown
Creator: Sha, W.T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Final Report of Modeling of CWM Droplet Combustion

Description: The objective of the present study was to develop a one-dimensional, unsteady state model for coal-water mixture droplet combustion, and to compare the characteristic times for the various processes, such as water vaporization, devolatilization and char oxidation with available experimental data. A water film surrounding a spherical coal particle is considered to undergo vaporization by heat transfer from the hot air. After the water vaporization is complete, devolatilization begins. This proce… more
Date: October 1, 1983
Creator: Pandalai, Krish; Aggarwal, Suresh & Sirignano, William
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Adaptive Mesh Refinement for 1-Dimensional Gas Dynamics

Description: We consider the solution of the one-dimensional equation of gas-dynamics. Accurate numerical solutions are difficult to obtain on a given spatial mesh because of the existence of physical regions where components of the exact solution are either discontinuous or have large gradient changes. Numerical methods treat these phenomena in a variety of ways. In this paper, the method of adaptive mesh refinement is used. A thorough description of this method for general hyperbolic systems is given else… more
Date: 1982-08~
Creator: Hedstrom, Gerald; Rodrigue, Garry; Berger, Marsha & Oliger, Joseph
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Non-linear numerical studies of the tearing mode

Description: A non-linear, time dependent, hydromagnetic model is developed and applied to the tearing mode, one of a class of instabilities which can occur in a magnetically confined plasma when the constraint of infinite conductivity is relaxed. The model is based on the eight partial differential equations of resistive magnetohydrodynamics (MHD). The equations are expressed as a set of conservation laws which conserves magnetic flux, momentum, mass, and total energy. These equations are then written in g… more
Date: January 1, 1978
Creator: Schnack, D.D. Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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D/sup -/ production by multiple charge-transfer collisions of low-energy D ions and atoms in cesium vapor

Description: The production of D/sup -/ by multiple charge-transfer collisions of a D/sup +/ beam in a cesium-vapor target is considered for D/sup +/ energies above 300 eV. The cross sections relevant to D/sup -/ formation are obtained by a least-squares fit of three-charge-state differential equations to experimental yield curves. Implications for production of intense negative-ion beams are discussed, and speculations are made about extrapolation to lower engeries.
Date: January 22, 1978
Creator: Hooper, E. B. Jr.; Willmann, P. A. & Schlachter, A. S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A semi-analytical method for heat sweep calculations in fractured reservoirs

Description: An analytical approximation is developed for purely conductive heat transfer from impermeable blocks of rock to fluids sweeping past the rocks in fractures. The method was incorporated into a multi-phase fluid and heat flow simulator. Comparison with exact analytical solutions and with simulations using a multiple interacting continua approach shows very good accuracy, with no increase in computing time compared to porous medium simulations. 14 refs., 3 figs., 5 tabs.
Date: January 1, 1988
Creator: Pruess, K. & Wu, Y.S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Electron bremsstrahlung angular-distribution fits for atomic numbers 1 less than or equal to Z less than or equal to 92, and incident-electron energies 1 keV less than or equal to T less than or equal to 500 keV

Description: The analytic fit of a simple expression to the electron bremsstrahlung angular distribution cross section d/sup 2/sigma/dkd..cap omega.. (differential in the emitted photon energy k and angle ..cap omega..) is investigated. Optimal choices for the fit parameters are determined and fit coefficients are tabulated for a large number of neutral-atom cases. Results are also presented for fits to the relativistic Coulomb-Born approximation. Comparisons between the screened neutral-atom results and th… more
Date: January 1, 1982
Creator: Kissel, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Transient thermal analysis of three fast-charging latent heat storage configurations for a space-based power system

Description: A space-based thermal storage application must accept large quantities of heat in a short period of time at an elevated temperature. A model of a lithium hydride phase change energy storage system was used to estimate reasonable physical dimensions for this application which included the use of a liquid metal heat transfer fluid. A finite difference computer code was developed and used to evaluate three methods of enhancing heat transfer in the PCM energy storage system. None of these three met… more
Date: January 1, 1988
Creator: Stovall, T. K. & Arimilli, R. V.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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FEMWATER: a finite-element model of water flow through saturated-unsaturated porous media

Description: Upon examining the Water Movement Through Saturated-Unsaturated Porous Media: A Finite-Element Galerkin Model, it was felt that the model should be modified and expanded. The modification is made in calculating the flow field in a manner consistent with the finite element approach, in evaluating the moisture-content increasing rate within the region of interest, and in numerically computing the nonlinear terms. With these modifications, the flow field is continuous everywhere in the flow regime… more
Date: October 1, 1980
Creator: Yeh, G.T. & Ward, D.S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Full-wave calculations in flux coordinates for toroidal geometry

Description: A new 2-D full-wave code, HYPERION, employing a poloidal and toroidal mode expansion and including the toroidal terms arising in the wave equation has been developed. It is based on the existing modules developed for the MHD stability codes and uses as input the tokamak equilibria calculated with the RSTEQ code. At present the plasma response is described by the collisionally broadened cold plasma conductivity. However, the code is written in straight field line coordinates, this permits the ac… more
Date: January 1, 1988
Creator: Carreras, B. A.; Lynch, V. E.; Jaeger, E. F. & Batchelor, D. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Commercial US nuclear reactors and waste: the current status

Description: Between March 1 and June 15, 1980, the declared size of the commercial light waste reactor (LWR) nuclear power industry in the US has decreased another 9 GWe. For the presently declared size: the 165 declared reactors will peak at a capacity of 153 GWe in 2001 and will consume about 870,000 MTU as enrichment feed; the theoretical rate of enrichment requirements will peak at about 19,000,000 SWUs/y in the year 2014; as few as two repositories each with capacity equivalent to 100,000 MTU would ho… more
Date: September 1, 1980
Creator: Platt, A.M. & Robinson, J.V.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Computational complexity in multidimensional neutron transport theory calculations. Final report

Description: Research to establish a general method to assess the performance and reliability of computer codes for the numerical approximation of linear operators is reported. The neutron transport operator was chosen as model. The general approach to solving the error problem and the use of benchmarks are sketched. This report contains only a brief administrative summary; references are given to forty reports and publications that contain detailed information. (RWR)
Date: December 1, 1979
Creator: Bareiss, E. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Solder fatigue reduction in point focus photovoltaic concentrator modules

Description: Solder fatigue tests have been conducted on point focus photovoltaic concentration cell assemblies to identify a baseline fatigue life and to quantify the fatigue life improvements that result using a copper-molybdenum-copper low-expansion insert between the solar cell and copper heat spreader. Solder microstructural changes and fatigue crack growth were identified using cross sections and ultrasonic scans of the fatigue solder joints. The Coffin-Manson and Total Strain fatigue models for low-c… more
Date: January 1, 1991
Creator: Hund, T. D. & Burchett, S. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Multi-grid and ICCG for problems with interfaces

Description: Computation times for the multi-grid (MG) algorithm, the incomplete Cholesky conjugate gradient (ICCG) algorithm (J. Comp. Phys. 26, 43-65 (1978); Math. Comp. 31, 148-162 (1977)), and the modified ICCG (MICCG) algorithm (BIT 18, 142-156 (1978)) to solve elliptic partial differential equations are compared. The MICCG and ICCG algorithms are more robust than the MG for general positive definite systems. A major advantage of the MG algorithm is that the structure of the problem can be exploited to… more
Date: January 1, 1980
Creator: Dendy, J.E. & Hyman, J.M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Dynamic modeling of transport and positional control of tokamaks

Description: We describe here a numerical model of a free boundary axisymmetric tokamak plasma and its associated control systems. The plasma is modeled with a hybrid method using two-dimensional velocity and flux functions with surface-averaged MHD equations describing the evolution of the adiabatic invariants. Equations are solved for the external circuits and for the effects of eddy currents in nearby conductors. The method is verified by application to several test problems and used to simulate the form… more
Date: October 1, 1985
Creator: Jardin, S. C.; Pomphrey, N. & DeLucia, J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Investigation of Celotex trademark charring depths in the DT-18 shipping container

Description: Celotex {trademark}, the insulating material used between the outer and inner containers of the DT-18 shipping package, undergoes decomposition, combustion, or both when heated to temperatures exceeding 150{degrees}C. Several DT-18 packages that had previously undergone hypothetical thermal accident testing were opened and Celotex {trademark} charring depths ranging from {1/2} to 1 {1/2} in. were recorded. The majority of char depth data taken was between 3/4 and 1 {1/4} in. One-dimensional HEA… more
Date: March 1, 1992
Creator: Anderson, J.C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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CHILES 2: a finite element computer program that calculates the intensities of linear elastic singularities in isotropic and orthotropic materials

Description: CHILES 2 is a finite-element computer program that calculates the strength of singularities in linear elastic bodies. A generalized quadrilateral finite element that includes a singular point at a corner node is incorporated in the code. The displacement formulation is used and interelement compatibility is maintained so that monotone convergence is preserved. Plane stress, plane strain, and axisymmetric conditions are treated. Isotropic and orthotropic crack tip singularity problems are solved… more
Date: February 1, 1978
Creator: Benzley, S.E. & Beisinger, Z.E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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ADIFOR: Automatic differentiation in a source translator environment

Description: The numerical methods employed in the solution of many scientific computing problems require the computation of derivatives of a function f: R{sup n} {yields} R{sup m}. ADIFOR (Automatic Differentiation in FORtran) is a source transformation tool that accepts Fortran 77 code for the computation of a function and writes portable Fortran 77 code for the computation of the derivatives. In contrast to previous approaches, ADIFOR views automatic differentiation as a source transformation problem and… more
Date: January 1, 1992
Creator: Bischof, C.; Corliss, G.; Griewank, A. (Argonne National Lab., IL (United States)) & Carle, A. (Rice Univ., Houston, TX (United States). Center for Research on Parallel Computation)
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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