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Multiple sine wave excitation of a hard spring oscillator

Description: The vibration testing of non-linear systems has not received much attention in the literature. Frequently, linear procedures are used in the hope that large differences between the linear and non-linear responses will not occur. This may be valid for certain small ranges of the non-linearity and for a single harmonic component excitation. However, for multi-component periodic inputs, there is very little guidance in the literature for even a qualitative evaluation of the probable response. With… more
Date: June 1, 1976
Creator: Curreri, J R & Bezler, P
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Parallel Multigrid Method for Neutronics Applications

Description: The multigrid method has been shown to be the most effective general method for solving the multi-dimensional diffusion equation encountered in neutronics. This being the method of choice, we develop a strategy for implementing the multigrid method on computers of massively parallel architecture. This leads us to strategies for parallelizing the relaxation, contraction (interpolation), and prolongation operators involved in the method. We then compare the efficiency of our parallel multigrid wi… more
Date: January 1, 2001
Creator: Alcouffe, Raymond E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Large eddy simulation of flow in LWR fuel bundles.

Description: Advances in computational fluid dynamics (CFD), turbulence modeling, and parallel computing have made feasible the development of codes that can simulate 3-D flows and heat transfer in realistic LWR fuel bundle geometries. Although no single existing RANS (Reynolds averaging of the Navier Stokes equations) turbulence model predicts a sufficiently wide range of flows with accuracy adequate for engineering needs, at this time for most flows the k-{epsilon} models seem to be the best choice. In Re… more
Date: August 17, 2001
Creator: Tzanos, C. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Hydrogen mixing study (HMS) in LWR type containments

Description: A numerical technique has been developed for calculating the full three-dimensional time-dependent Navier-Stokes equations with multiple speies transport. The method is a modified form of the Implicit Continuous-fluid Eulerian (ICE) technique to solve the governing equations for low Mach number flows where pressure waves and local variations in compression and expansion are not significant. Large density variations, due to thermal and species concentration gradients, are accounted for without t… more
Date: January 1, 1983
Creator: Travis, J.R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Blackness coefficients, effective diffusion parameters, and control rod worths for thermal reactors - methods

Description: Simple diffusion theory cannot be used to evaluate control rod worths in thermal neutron reactors because of the strongly absorbing character of the control material. However, reliable control rod worths can be obtained within the framework of diffusion theory if the control material is characterized by a set of mesh-dependent effective diffusion parameters. For thin slab absorbers the effective diffusion parameters can be expressed as functions of a suitably-defined pair of blackness coefficie… more
Date: January 1, 1984
Creator: Bretscher, M.M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Alternate differencing technique for the synthetic method

Description: Larsen and coworkers have shown that the effectiveness of the synthetic method is often determined by the techniques used to difference the diffusion equation, the equation taken, in current forms of the synthetic method, as the low-order approximation. They have also developed their own differencing technique. On the other hand, the Los Alamos (LA) approach generates point-centered diffusion difference equations, a feature which is inconvenient for the many people now using box-centered codes.… more
Date: January 1, 1983
Creator: Gelbard, E.M. & Khalil, H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Reactor kinetics methods development. Final report

Description: This report is a qualitative summary of research conducted at MIT from 1967 to 1977 in the area of reactor kinetics methods. The objectives of the research were to find methods of integration of various mathematical models of nuclear reactor transients. From the beginning the work was aimed at numerical integration methods. Specific areas of research, discussed in more detail following, included: integration of multigroup diffusion theory models by finite difference and finite element methods; … more
Date: January 8, 1978
Creator: Hansen, K. F. & Henry, A. F.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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HMS-burn: a model for hydrogen distribution and combustion in nuclear reactor containments

Description: It is now possible to analyze the time-dependent, fully three-dimensional behavior of hydrogen combustion in nuclear reactor containments. This analysis involves coupling the full Navier-Stokes equations with multi-species transport to the global chemical kinetics of hydrogen combustion. A transport equation for the subgrid scale turbulent kinetic energy density is solved to produce the time and space dependent turbulent transport coefficients. The heat transfer coefficient governing the exchan… more
Date: January 1, 1985
Creator: Travis, J. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simplified plutonium conversion expression

Description: An accurate, simplified expression relating Pu conversion to exposure, was found which could be substituted for the lengthy subroutine used to calculate conversions in the Process Optimization Program.
Date: January 18, 1961
Creator: Jensen, R. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The Boundary Element Formulation of the 1-Group, 1-D Nodal Equations

Description: A boundary element method is developed for the 1-D nodal diffusion equation in cylindrical geometry. This method retains the matrix qualities of the nodal formulation while providing an accurate computational benchmark for evaluating reactor analysis codes.
Date: June 1, 2006
Creator: Ganapol, B. D. & Ougouag, Abderrafi M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Lumped-parameter models for transient conduction in nuclear reactor components

Description: Lumped-parameter models are presented for the prediction of transient conduction in cylinders, plane-parallel slabs, tubes and fuel elements under conditions of small-break loss of coolant accidents and planned transients in nuclear reactor systems. The model accounts for heat generation by fission and decay and by gamma absorption and water reaction. The models consist of ordinary differential equations, one each for the solid cylinder, the slab and the tube, and two for fuel pellet and clad i… more
Date: June 1, 1980
Creator: Wulff, W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Simulation of Natural Convection in a Rectangular Loop Using Finite Elements

Description: A two-dimensional finite-element analysis of natural convection in a rectangular loop is presented. A psi-omega formulation of the Boussinesque approximation to the Navier-Stokes equation is solved by the false transient technique. Streamlines and isotherms at Ra = 10/sup 4/ are shown for three different modes of heating. The results indicate that corner effects should be considered when modeling flow patterns in thermosyphons.
Date: January 1, 1984
Creator: Pepper, D. W.; Hamm, L. L. & Kehoe, A. B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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MOOSE: A PARALLEL COMPUTATIONAL FRAMEWORK FOR COUPLED SYSTEMS OF NONLINEAR EQUATIONS.

Description: Systems of coupled, nonlinear partial di?erential equations often arise in sim- ulation of nuclear processes. MOOSE: Multiphysics Ob ject Oriented Simulation Environment, a parallel computational framework targeted at solving these systems is presented. As opposed to traditional data / ?ow oriented com- putational frameworks, MOOSE is instead founded on mathematics based on Jacobian-free Newton Krylov (JFNK). Utilizing the mathematical structure present in JFNK, physics are modularized into “Ke… more
Date: May 1, 2009
Creator: Hansen, G.; Newman, C. & Gaston, D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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A Piecewise Linear Finite Element Discretization of the Diffusion Equation for Arbitrary Polyhedral Grids

Description: We develop a piecewise linear (PWL) Galerkin finite element spatial discretization for the multi-dimensional radiation diffusion equation. It uses piecewise linear weight and basis functions in the finite element approximation, and it can be applied on arbitrary polygonal (2D) or polyhedral (3D) grids. We show that this new PWL method gives solutions comparable to those from Palmer's finite-volume method. However, since the PWL method produces a symmetric positive definite coefficient matrix, i… more
Date: July 15, 2005
Creator: Bailey, T S; Adams, M L; Yang, B & Zika, M R
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Solving the uncommon reactor core neutronics problems

Description: The common reactor core neutronics problems have fundamental neutron space, energy spectrum solutions. Typically the most positive eigenvalue is associated with an all-positive flux for the pseudo-steady-state condition (k/sub eff/), or the critical state is to be effected by selective adjustment of some variable such as the fuel concentration. With sophistication in reactor analysis has come the demand for solutions of other, uncommon neutronics problems. Importance functionss are needed for s… more
Date: January 1, 1980
Creator: Vondy, D.R. & Fowler, T.B.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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An improved quasistatic option for the DIF3D nodal kinetics code

Description: An improved quasistatic scheme is formulated for solution of the time-dependent DIF3D nodal equations in hexagonal-z geometry. This scheme has been implemented, along with adiabatic and point kinetics solution options, in the DIF3D hexagonal-z nodal kinetics code. The improved quasistatic method is shown to permit significant reduction in computing time, even for transients involving pronounced changes in flux shape. The achievable computing time reduction, in addition to being problem dependen… more
Date: January 1, 1991
Creator: Taiwo, T. A. & Khalil, H. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Recovery Discontinuous Galerkin Jacobian-Free Newton-Krylov Method for All-Speed Flows

Description: A novel numerical algorithm (rDG-JFNK) for all-speed fluid flows with heat conduction and viscosity is introduced. The rDG-JFNK combines the Discontinuous Galerkin spatial discretization with the implicit Runge-Kutta time integration under the Jacobian-free Newton-Krylov framework. We solve fully-compressible Navier-Stokes equations without operator-splitting of hyperbolic, diffusion and reaction terms, which enables fully-coupled high-order temporal discretization. The stability constraint is … more
Date: July 1, 2008
Creator: Park, HyeongKae; Nourgaliev, Robert; Mousseau, Vincent & Knoll, Dana
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Analysis of quality certification data: WARP, TFC and delta OD{sub 2} as a function of reactor operating conditions

Description: This report is the second in a series on the definition of performance of irradiated fuel elements as measured by the Quality Certification Program. Objectives of this analysis are to establish empirical mathematical relations which fit observed data from > 2000 fuel elements measurements for WARP, TFC, and DELTA OD{sub 2}, as a function of reactor conditions (power, surface temperature, time).
Date: November 23, 1960
Creator: Hagie, L. T. & Jaech, J. L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Modeling of eddy current NDE probe for steam generator tubes.

Description: Calculations were performed with a three-dimensional (3-D) finite-element model to describe the response of an eddy current (EC) probe to defects in steam generator (SG) tubing of a nuclear reactor. Such calculations could be very helpful in understanding and interpreting the EC probe response to complex tube/defect geometries associated with longitudinal inner/outer notches, roll transitions, sludge, and through-wall holes in SG tubes. The governing field equations are derived in terms of coup… more
Date: January 29, 2003
Creator: Chang, F. C.; Bakhtiari, S. & Kupperman, D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Coupling parameters for partially reflected reactors

Description: For situations in which the standard point kinetic model does not adequately characterize the kinetic behavior of a reflected system, the Avery-Cohn differential equations can be used. However, these equations require that one determine the coupling parameters between the core and the reflector, f{sub cr} and f{sub rc}. The coupling parameter, f{sub cr}, represents the probability that a neutron in the core will leak into the reflector, and the coupling parameter, f{sub rc}, represents the prob… more
Date: July 1, 1995
Creator: Busch, R. D. & Spriggs, G. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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