Convergence properties were investigated for the response matrix method with various finite-difference formulations that can be utilized in the nonlinear acceleration method. The nonlinear acceleration method is commonly used for the diffusion calculation with the advanced nodal method or the transport calculation with the method of ...
Energy Citations Database
... in a one-dimensional, discrete lattice is generated by accelerating the end-most particle from zero to its final velocity in a finite rise time after which ...
DTIC Science & Technology
We discuss the use of 3-D finite-difference time-domain (FDTD) electromagnetic codes for modeling accelerator components. Computational modeling of cylindrically symmetric structures such as induction accelerator cells has been very successful in predicti...
National Technical Information Service (NTIS)
... HARDWARE ACCELERATOR ... these equations can handle isotropic, inhomogeneous, lossy magnetic and lossy ... as O(n 2), where n is the linear ...
Finite Difference Time Domain (FDTD) modelling has been successfully applied to a wide variety of electromagnetic scattering and interaction problems for many years. Here the method is extended to incorporate the modelling of wake fields in particle accelerators. Algorithmic comparisons are made to existing wake field codes, such as ...
DOE Information Bridge
Omega3P is a parallel eigenmode calculation code for accelerator cavities in frequency domain analysis using finite-element methods. In this report, we will present detailed finite-element formulations and resulting eigenvalue problems for lossless cavities, cavities with lossy materials, cavities with imperfectly conducting surfaces, ...
... Title : Finite Element, Finite Difference, and Finite Volume Methods: Examples and their Comparisons. Descriptive Note : Final rept. Jan-Jul 95,. ...
The view of considering global Pseudospectral methods (Sinc and Fourier) as the infinite order limit of local finite difference methods, and vice versa, finite difference as a certain sum acceleration of the pseudospectral methods is exploited to investigate high order ...
NASA Astrophysics Data System (ADS)
The dielectric wall accelerator (DWA) is a compact induction accelerator structure that incorporates the accelerating mechanism, pulse forming structure, and switch structure into an integrated module. The DWA consists of stacked stripline Blumlein assemblies, which can provide accelerating gradients in excess of ...
Elementary descriptions of finite element and finite difference methods are given while the finite volume method is briefly overviewed. Examples illustrating finite element and finite difference methods are worked out. Finally, comparisons of these ...
A new benchmarking concept is presented for verifying the PEBBED 3D multigroup finite difference/nodal diffusion code with application to pebble bed modular reactors (PBMRs). The key idea is to perform convergence acceleration, also called extrapolation to zero discretization, of a basic finite ...
... Title : An Investigation of the Method of Finite Elements with Accuracy Comparisons to the Method of Finite Differences for Solution of the Transient ...
In this talk I will discuss two relatively simple finite difference schemes that are extremely effective in capturing the finite-time blow-up exhibited by nonlinear acceleration waves under certain conditions. We will test these schemes in the context of an initial-boundary value problem that involves a sinusoidal ...
This work is intended to be a study into the application of the finite-difference time-domain, or FD-TD technique, to some of the problems faced by designers of equipment used in modern accelerators. In particular it discusses using the FD-TD algorithm to study the field distribution of a simple two-dimensional cavity in both space and time. 18 refs.
This study investigates two methods of increasing the rate of convergence of the two dimensional five point implicit finite difference representation of the diffusion equation of transient heat transfer. The two methods are adapted Wegstein and successive...
A series of impact experiments on anhydrite CaSO4, in which vaporized sample accelerates an element in a velocity interferometer, generate velocity data that we have recently reanalyzed using an explicit entropy generating finite difference code. The shoc...
Field emission gun, optical properties are recalled; the different methods to get the electrostatic potential are recalled too, more specifically the finite element method. The electron optics properties of the field emission tetrode guns are studied; spe...
A new benchmarking concept is presented for verifying the PEBBED 3D multigroup finite difference/nodal diffusion code with application to pebble bed modular reactors (PBMRs). The key idea is to perform convergence acceleration, also called extrapolation t...
The convergence properties of several nonlinear solution procedures were examined with respect to the accelerated flow of a fluid in a converging channel (the Hamel problem), using two different finite element computer programs with different elemental construction. The Reynolds number varied from that for creeping ...
A finite element field solver for dipole modes in axisymmetric structures has been written. The second-order elements used in this formulation yield accurate mode frequencies with no spurious modes. Quasi-periodic boundaries are included to allow travelling waves in periodic structures. The solver is useful in applications requiring precise frequency calculations such as ...
... Title : THE EFFECT OF FINITE DIFFERENCES ON THE GROWTH RATES OF UNSTABLE WAVES IN A SIMPLE BAROCLINIC MODEL. ...
... Title : ON THE FORMULATION OF FINITE DIFFERENCE ANALOGUES OF THE DIRICHLET PROBLEM FOR POISSON'S EQUATION. ...
Calculate computational work required to model heat conduction using finite differences with explicit timestepping.
NSDL National Science Digital Library
... the finite difference solutions to the ... the weak sense solution to the ... DIFFERENTIAL EQUATIONS, STOCHASTIC PROCESSES, MEASURE ...
... FINITE DIFFERENCE SOLUTION OF THE LAMINAR COMPRESSIBLE BOUNDARY LAYER EQUATIONS IN THE VON MISES VARIABLES WITH ...
An exponential finite difference scheme first presented by Bhattacharya for one dimensional unsteady
NASA Technical Reports Server (NTRS)
... Descriptors : *FINITE DIFFERENCE THEORY, *THERMAL DIFFUSION, *THERMAL CONDUCTIVITY, *PARTIAL DIFFERENTIAL EQUATIONS ...
... OF THE APPLICATION OF FINITE -DIFFERENCE TECHNIQUES TO ULF WAVES IN A SPHERICAL MODEL INHOMOGENEOUS, ANISOTROPIC ...
Proton accelerator structures for medical applications using Dielectric Wall Accelerator (DWA) technology allow for the utilization of high electric field gradients on the order of 100 MV/m to accelerate the proton bunch. Medical applications involving cancer therapy treatment usually desire short bunch lengths on the order of hundreds ...
This study compares a vigorous shaking and an inflicted impact, defined as the terminal portion of a vigorous shaking, using a finite element model of a 6-month-old child head. Whereas the calculated values in terms of shearing stress and brain pressure remain different and corroborate the previous studies based on angular and linear velocity and ...
PubMed
We describe an iterative algorithm to solve electronic structure problems in Density Functional Theory. The approach is presented as a Subspace Accelerated Inexact Newton (SAIN) solver for the non-linear Kohn-Sham equations. It is related to a class of iterative algorithms known as RMM-DIIS in the electronic structure community. The method is illustrated with examples of real ...
Field strength measurements for the determination of the R/Q of a mm-wave, 50-MeV electron linear accelerator using perturbational techniques are described. The perturbation is achieved using optical fibers coated with a thin metallic film to form a hollow cylinder. The perturbational form factors for such a geometry are approximated using several simple analytical expressions ...
Shock propagation in a one-dimensional, discrete lattice is generated by accelerating the end-most particle from zero to its final velocity in a finite rise time after which the end particle is maintained at that velocity. The wave profiles for various ri...
A new diffusion-synthetic acceleration scheme is developed for solving the 2-D S{sub n} equations in X-Y geometry with bilinear- discontinuous finite-element spatial discretization. This method differs from previous methods in that it is unconditionally efficient fore problems with isotropic or weakly anisotropic scattering. ...
A new diffusion-synthetic acceleration scheme is developed for solving the 2-D S[sub n] equations in X-Y geometry with bilinear- discontinuous finite-element spatial discretization. This method differs from previous methods in that it is unconditionally efficient fore problems with isotropic or weakly anisotropic scattering. ...
... Descriptors : *ACCELERATION, *FINITE ELEMENT ANALYSIS, *SHELTERS, *DYNAMIC LOADS, STRESSES, MATHEMATICAL MODELS, MASS ...
... 2001-11 High Order Finite Difference and Finite Volume WENO Schemes and Discontinuous Galerkin Methods for CFD Chi-Wang Shu ...
... ADA390653. Title : High Order Finite Difference and Finite Volume WENO Schemes and Discontinuous Galerkin Methods for CFD. ...
Simulations are presented for a laser-driven cyclotron autoresonance accelerator with a practical guide magnetic field, as produced by a single coil. Effects that are investigated include acceleration in the non-resonant magnetic field profile, reduced acceleration due to misalignment between the magnetic field axis and the laser beam ...
Finite laser beam particle simulations of beat wave acceleration show that a coherent plasma wave excited by two-colinear laser beams at a difference frequency equal to the plasma frequency can produce maximum electron energies as predicted by simple one-dimensional theory. The time to saturation and the saturation amplitude of the ...
If expanding and contracting regions coexist in the universe, the speed of the cosmic volume expansion can be accelerated. We construct simple inhomogeneous dust-filled universe models in which the speed of the cosmic volume expansion is accelerated for finite periods. These models are constructed by removing spherical domains from the ...
Very basic principles are reviewed in this lecture: The concepts of Finite Volumes and numerical stability (implicit and explicit).
... The finite element models for the staggered vertical grids did not perform up to their possibilities due to the boundary elements. ...
... Modifications were made on Jordan's (1985) Galerkin finite element approximation for two staggered grids. Comparisons ...
This paper summarizes the results of the dynamic response analysis of the Zion reactor containment building using three different soil-structure interaction (SSI) analytical procedures which are: the substructure method, CLASSI; the equivalent linear finite element approach, ALUSH; and the nonlinear finite element procedure, DYNA3D. ...
... behavior using the Finite Difference method; examples of non ... DIFFERENCE EQUATIONS, THESES, HEAT EXCHANGERS, FINITE DIFFERENCE ...
A novel approach is proposed for charged particle transport calculations using a recently developed second-order, self-adjoint angular flux (SAAF) form of the Boltzmann transport equation with continuous slowing-down. A finite element discretization that is linear continuous in space and linear discontinuous (LD) in energy is described and implemented in a one-dimensional, ...
DYNA2D is an explicit two-dimensional plane strain and axisymmetric Lagrangian finite element and finite difference code. Spatial discretization may be accomplished by constant-stress elements that can be degenerated to triangular zones, constant-pressure variable-node elements, nine-node Lagrange elements, or ...
... Abstract : The computer program FIDO (Finite Difference Ocean acoustic model) computes the real acoustic pressure via a finite- difference ...
... Title : A Generalized Finite-Difference Formulation for the US Geological Survey Modular Three-Dimensional Finite-Difference Ground-Water Flow ...
... current and cancelled), Joint Staff and ... of Test Problems for Finite Element/Finite Difference Programs for ... Calculations using ABAQUS for the pinned ...
upper airway has provided insights into vocal tract shaping and data for its modeling. Small movements of articulators can lead to large changes in the produced sound, therefore improving the resolution of these data sets, within the constraints of a sustained speech sound (6�12 s), is an important area for investigation. The purpose of the study is to provide a first application of compressed ...
E-print Network
We accelerate a 3-D finite-difference in the time domain wave propagation code by a factor between about 20 and 60 compared to a serial implementation using graphics processing unit computing on NVIDIA graphics cards with the CUDA programming language. We describe the implementation of the code in CUDA to simulate the propagation of seismic waves in a ...
Comprehensive coverage of computational methods for differential equations in engineering and science is provided. Three categories of computational methods, the finite difference method, the finite element method, and the statistical (Monte Carlo) method, provide numerical solutions of eigenvalue problems of ordinary differential ...
A new combination of a finite volume discretization in conjunction with carefully designed dissipative terms of third order, and a Runge Kutta time stepping scheme, is shown to yield an effective method for solving the Euler equations in arbitrary geometric domains. The method has been used to determine the steady transonic flow past an airfoil using an O mesh. Convergence to ...
The movement and shaping of the current sheath in coaxial plasma guns is numerically modelled by means of a dynamic finite-elements representation. Numerical instabilities are avoided by a reshaping algorithm applied during the tracking of the current sheath acceleration. Improving upon older versions of the algorithm, the present model includes a delay ...
The dissertation is concerned with the use of iterative algorithms to obtain numerical solutions of large systems of linear algebraic equations with sparse matrices. Such systems often arise in the numerical solution of partial differential equations by finite difference methods and by finite element methods. The emphasis is on the use ...
