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RODCON: a finite difference heat conduction computer code in cylindrical coordinates

Description: RODCON, a finite difference computer code, was developed to calculate the internal temperature distribution of the fuel rod simulator (FRS) for the Core Flow Test Loop (CFTL). RODCON solves the implicit, time-dependent forward-differencing heat transfer equation in 2-dimensional (Rtheta) cylindrical coordinates at an axial plane with user specified radial material zones and surface conditions at the FRS periphery. Symmetry of the boundary conditions of coolant bulk temperatures and film coeffic… more
Date: September 16, 1980
Creator: Conklin, J. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Cedar Project---Original goals and progress to date

Description: This report describes: Cedar System Hardware; Compiler and Software Issues on Memory Management; Operating Systems; Compilers; and Multiprocessor Performance on Algorithms and Applications.
Date: September 5, 1991
Creator: Cybenko, G.; Kuck, D.; Padua, D. & Gallopoulos, E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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New approaches to linear and nonlinear programming

Description: This report describes technical progress during the past twelve months on DOE Contract DE-FG-87ER25030 and requests support for the third year. The project involves study of the theoretical properties and computational performance of techniques that solve linear and nonlinear programs by means of nonlinear transformations. The group at the Systems Optimization Laboratory (SOL) were the first to recognize the connection between Karmarkar's projective method and the logarithmic barrier method. It… more
Date: September 1, 1988
Creator: Murray, W. & Saunders, M.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A nonvariational code for calculating three-dimensional MHD (magnetohydrodynamic) equilibria

Description: Details are presented of the PIES code, which uses a nonvariational algorithm for calculating fully three-dimensional MHD equilibria. The MHD equilibrium equations are directly iterated in special coordinates to find self-consistent currents and magnetic fields for given pressure and current profiles and for a given outermost magnetic surface. Three important advantages of this approach over previous methods are the ease with which net current profiles can be imposed, the explicit treatment of … more
Date: September 1, 1987
Creator: Greenside, H.S.; Reiman, A.H. & Salas, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Two-dimensional fluid and thermal analysis of dry porous rock reservoirs for CAES

Description: The analysis of the hydrodynamic and thermodynamic response of a Compressed Air Energy Storage (CAES) dry porous media reservoir subjected to daily air mass cycling is described. The analysis is based upon a numerical computer model that uses a finite difference method to solve the two-dimensional (r-z) conservation equations for the transport of mass, momentum, and energy in the below ground system. The investigation quantifies the behavior of those parameters that enter the model by virtue of… more
Date: September 1, 1979
Creator: Wiles, L.E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Modified Runge-Kutta methods for solving odes

Description: A class of Runge-Kutta formulas is examined which permit the calculation of an accurate solution anywhere in the interval of integration. This is used in a code which seldom has to reject a step; rather it takes a reduced step if the estimated error is too large. The absolute stability implications of this are examined.
Date: September 1, 1981
Creator: Van Vu, T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Studies in Semiconducting Metal Oxides in Conjunction With Silicon for Solid State Gas Sensors. Progress Report, April 1, 1977-September 30,1979

Description: A fundamental investigation of SnO/sub 2/ and ZnO thin films with emphasis on their use in solid state gas detection is discussed. Methods of thin film preparation, described here, include the chemical vapor deposition (CVD) technique for SnO/sub 2/ films and the radio frequency sputtering technique for SnO/sub 2/ and ZnO films. The use of Auger electron spectroscopy, (AES), transmission electron microscopy, (TEM) and x ray diffractometry, (XRD) in the analysis of these films is reported. Caref… more
Date: September 1, 1979
Creator: Jordan, A. G. & Advani, G. N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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HYDRA-II: A hydrothermal analysis computer code: Volume 2, User's manual

Description: HYDRA-II is a hydrothermal computer code capable of three-dimensional analysis of coupled conduction, convection, and thermal radiation problems. This code is especially appropriate for simulating the steady-state performance of spent fuel storage systems. The code has been evaluated for this application for the US Department of Energy's Commercial Spent Fuel Management Program. HYDRA-II provides a finite-difference solution in cartesian coordinates to the equations governing the conservation o… more
Date: September 1, 1987
Creator: McCann, R. A.; Lowery, P. S. & Lessor, D. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Computer modeling of fluid flow and combustion in the ISV (In Situ Vitrification) confinement hood

Description: Safety and suitability objectives for the application of the In Situ Vitrification (ISV) technology at the INEL require that the physical processes involved in ISVV be modeled to determine their operational behavior. The mathematical models that have been determined to address the modeling needs adequately for the ISV analysis package are detailed elsewhere. The present report is concerned with the models required for simulating the reacting flow that occurs in the ISV confinement hood. An expe… more
Date: September 1, 1990
Creator: Johnson, R. W. & Paik, S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Temporal Scattering And Response software: Users' manual

Description: This manual gives complete information on how to use the TSAR electromagnetic analysis software. Included are descriptions of input files, the details of how these files affect the problem, and output data specifications. What is not included is the theory of the finite-difference time-domain (FDTD) algorithm or details of the TSAR implementation of it. This manual assumes that readers are sufficiently familiar with FDTD that they only need the how to'' knowledge presented here. For further inf… more
Date: September 1, 1990
Creator: McLeod, R.R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Large-scale sequential quadratic programming algorithms

Description: The problem addressed is the general nonlinear programming problem: finding a local minimizer for a nonlinear function subject to a mixture of nonlinear equality and inequality constraints. The methods studied are in the class of sequential quadratic programming (SQP) algorithms, which have previously proved successful for problems of moderate size. Our goal is to devise an SQP algorithm that is applicable to large-scale optimization problems, using sparse data structures and storing less curva… more
Date: September 1, 1992
Creator: Eldersveld, S.K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

A numerical theory of lattice gas and lattice Boltzmann methods in the computation of solutions to nonlinear advective-diffusive systems

Description: A numerical theory for the massively parallel lattice gas and lattice Boltzmann methods for computing solutions to nonlinear advective-diffusive systems is introduced. The convergence theory is based on consistency and stability arguments that are supported by the discrete Chapman-Enskog expansion (for consistency) and conditions of monotonicity (in establishing stability). The theory is applied to four lattice methods: Two of the methods are for some two-dimensional nonlinear diffusion equatio… more
Date: September 24, 1990
Creator: Elton, A.B.H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

An asymptotic symmetry of the rapidly forced pendulum

Description: The inhomogeneous differential equation (x{double prime} + sin x = {delta} sin (t + t{sub 0}){var epsilon}) describes the motion of a sinusoidally forced pendulum. The orbits that connect the two saddle points of the unforced ({delta} = 0) pendulum, (x = {pi}) and (x = {minus}{pi}), are called separatrices. If {var epsilon} {Omicron}(1), then one can use Melnikov's method to show that these separatrices can split for weak forcing ({delta} {much lt} 1), and that the perturbed motion is chaotic. … more
Date: September 1990
Creator: Chang, Yi-Hua & Segur, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Computing the eigenvalues and eigenvectors of a general matrix by reduction to general tridiagonal form

Description: This paper describes programs to reduce a nonsymmetric matrix to tridiagonal form, compute the eigenvalues of the tridiagonal matrix, improve the accuracy of an eigenvalue, and compute the corresponding eigenvector. 8 refs., 3 tabs.
Date: September 1, 1990
Creator: Dongarra, J. J.; Geist, G. A. & Romine, C. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Numerical methods for boundary value problems in differential-algebraic equations

Description: Differential-algebraic equation (DAE) boundary value problems arise in a variety of applications, including optimal control and parameter estimation for constrained systems. In this paper we survey these applications and explore some of the difficulties associated with solving the resulting DAE systems. For finite difference methods, the need to maintain stability in the differential part of the system often necessitates the use of methods based on symmetric discretizations. However, these meth… more
Date: September 24, 1990
Creator: Ascher, U.M. (British Columbia Univ., Vancouver, BC (Canada). Dept. of Computer Science) & Petzold, L.R. (Lawrence Livermore National Lab., CA (USA))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Theoretical temperature fields for the Stripa heater project. Vol. 1

Description: The report concerns thermal conduction calculations for the three in-situ heater experiments at Stripa which constitute part of the Swedish-American Cooperative Program on Radioactive Waste Storage in Mined Caverns. A semianalytic solution based on the Green's function method has been developed for an array of arbitrary time-dependent finite line heaters in a semi-infinite medium. This method as well as a three dimensional numerical model using IFD (Integrated Finite Difference) technique has b… more
Date: September 1, 1978
Creator: Chan, T.; Cook, N. G. W. & Tsang, C. F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Enhanced algorithms for stochastic programming

Description: In this dissertation, we present some of the recent advances made in solving two-stage stochastic linear programming problems of large size and complexity. Decomposition and sampling are two fundamental components of techniques to solve stochastic optimization problems. We describe improvements to the current techniques in both these areas. We studied different ways of using importance sampling techniques in the context of Stochastic programming, by varying the choice of approximation functions… more
Date: September 1, 1993
Creator: Krishna, A. S.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Reducing communication costs in the conjugate gradient algorithm on distributed memory multiprocessors

Description: The standard formulation of the conjugate gradient algorithm involves two inner product computations. The results of these two inner products are needed to update the search direction and the computed solution. In a distributed memory parallel environment, the computation and subsequent distribution of these two values requires two separate communication and synchronization phases. In this paper, we present a mathematically equivalent rearrangement of the standard algorithm that reduces the num… more
Date: September 1, 1992
Creator: D`Azevedo, E. F. & Romine, C. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Computer simulation of two-phase flow in nuclear reactors

Description: Two-phase flow models dominate the economic resource requirements for development and use of computer codes for analyzing thermohydraulic transients in nuclear power plants. Six principles are presented on mathematical modeling and selection of numerical methods, along with suggestions on programming and machine selection, all aimed at reducing the cost of analysis. Computer simulation is contrasted with traditional computer calculation. The advantages of run-time interactive access operation i… more
Date: September 1, 1992
Creator: Wulff, W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Bias removal for conventional magnetotelluric data

Description: An algorithm has been developed for the removal of autopower bias errors from conventional magnetotelluric (MT) data. Nonlinear equations involving autopowers as unknowns with crosspower coefficients are obtained by cross substitutions between the eight referenced impedance equations to eliminate the four impedances. Although exact solutions to the nonlinear equations can be computed, they are often sensitive to noise components in the crosspower coefficients, due to degeneracy of the equations… more
Date: September 1, 1983
Creator: Stodt, J. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Reducing communication costs in the conjugate gradient algorithm on distributed memory multiprocessors

Description: The standard formulation of the conjugate gradient algorithm involves two inner product computations. The results of these two inner products are needed to update the search direction and the computed solution. In a distributed memory parallel environment, the computation and subsequent distribution of these two values requires two separate communication and synchronization phases. In this paper, we present a mathematically equivalent rearrangement of the standard algorithm that reduces the num… more
Date: September 1, 1992
Creator: D'Azevedo, E. F. & Romine, C. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Modeling the temperature-dependent scale accumulation from geothermal brine

Description: A simple model for calculating the temperature-dependent deposition of silica scale from geothermal brine is outlined. A finite-difference technique for solving the moving boundary problem is described. The implicit formulation is solved directly, using matrix inverse methods appropriate for banded matrices. The multimaterial problem is defined in a way that maintains the compact matrix bandwidth of a single material. Sample problems are presented in dimensionless form, including a comparison b… more
Date: September 23, 1976
Creator: Schroeder, R. C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Observations on the operation of the SEMPEX code

Description: Observations on the use of the SEMPEX computer code are given. The issues of proper sampling rate and total sampling interval are addressed. The effect that noise in the data has on the results and the ability of autocorrelation, truncation filtering, and the sliding-window technique to reduce these effects are also discussed. 35 figures, 24 tables.
Date: September 22, 1977
Creator: Hudson, H. G. & Lager, D. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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