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Showing 1 to 20 of 52 for “"Helmholtz equation."”.

  1. Compressed absorbing boundary conditions for the Helmholtz equation

    Bélanger-Rioux, RosalieMassachusetts Institute of Technology2014

    … of an absorbing boundary condition for the Helmholtz equation in a heterogeneous medium. It is always possible to reduce an absorbing layer to an operator at the boundary by layer-stripping elimination of the exterior unknowns, but the linear algebra involved is costly. We propose to bypass …

    mit Repository record

  2. Fast and scalable solvers for the Helmholtz equation

    Zepeda-Núñ̃ez, Leonardo AndrésMassachusetts Institute of Technology2015

    … algorithms to solve the 2D high-frequency Helmholtz equation in heterogeneous medium. The algorithms rely on a layered domain decomposition and a coupling between subdomains using the Green's representation formula, which reduces the problem to a boundary integral system at the interfaces …

    mit Repository record

  3. Helmholtz Equation Least Squares Based Near-Field Acoustic Holography With Laser

    Zhu, Wu2016

    <p>This dissertation presents the HELS based NAH with laser and use normal surface velocity as input in near-field acoustic holography. The conventional HELS based NAH uses acoustic pressure as input to reconstruct sound field quantities, while this modified HELS based NAH with laser utilizes the …

    wayne-thes Repository record

  4. Reconstruction Resolution Of Coherent Point Sources With Helmholtz Equation Least Squares

    Dziklinski, Richard Edward2011

    … reconstruction of coherent point sources using Helmholtz Equation Least Squares (HELS) method based on measurements in violation of Nearfield Acoustical Holography (NAH) resolution guidelines. In HELS, the Helmholtz equation is solved by matching a series of localized spherical expansion …

    wayne-thes Repository record

  5. Periodic orbit analysis of the Helmholtz equation in two-dimensional enclosures

    Ham, ChristopherUniversity of Southampton2008

    … used in acoustics to understand solutions of the Helmholtz equation. A review of the links between ray and wave mechanics is given including WKBJ (Wentzel, Kramers, Brillouin and Jeffreys) and EBK (Einstein, Brillouin, Keller) methods. It is also noted that some mode shapes in chaotic enclosures …

    soton Repository record

  6. A Coarse Mesh Nodal Method for Solving the MultiDimensional Helmholtz Equation

    Bosnic, Don P.2017

    Made available in DSpace on 2017-07-06T18:42:29Z (GMT). No. of bitstreams: 3 Bosnic_Don_P_MS.pdf: 33492823 bytes, checksum: 82a1bfe934175084c06ed6af875ec7cc (MD5) Bosnic_Don_P_MS_ABS.pdf: 496288 bytes, checksum: 0c4e1361066079bfebbfc8f7e75a0808 (MD5) license.txt: 4813 bytes, checksum: …

    uiuc Repository record

  7. Structure Borne Noise Analysis Using Helmholtz Equation Least Squares Based Forced Vibro Acoustic Components

    Natarajan, Logesh Kumar2012

    … noise reduction. The core of this technology is Helmholtz equation least squares (HELS) based nearfield acoustic holography method. In this study, the HELS formulations derived in spherical co-ordinates using spherical wave expansion functions utilize the input data of acoustic pressures measured …

    wayne-thes Repository record

  8. Optimization of Plane Wave Directions in Plane Wave Discontinuous Galerkin Methods for the Helmholtz Equation

    Agrawal, Akshay 1990-University of Houston2016

    … as DG-Trefftz methods. In particular, for the 2D Helmholtz equation, plane waves have been used to derive an Interior Penalty (IP) type Plane Wave DG (PWDG) method and to provide an a priori error analysis of its p-version with respect to equidistributed plane wave directions. However, the …

    houston Repository record

  9. Modeling three-dimensional acoustic propagation in underwater waveguides using the longitudinally invariant finite element method

    Goldsberry, Benjamin MichaelThe University of Texas at Austin2014

    … a transform is applied to the three-dimensional Helmholtz equation to remove the range-independent dimension. The finite element method is employed to solve the transformed Helmholtz equation for each out-of-plane wavenumber. Finally, the inverse transform is used to transform the pressure field …

    texas Repository record

  10. Scattering at threshold in massive wave propagation and ionization

    Sussman, Ethan W.Massachusetts Institute of Technology2023

    … at infinity for two PDEs, the Schrödinger–Helmholtz equation with an attractive long range potential and the Klein–Gordon equation. In the former case, the transition occurs as the spectral parameter 𝐸 → 0⁺, and thus describes the ionization of Hydrogenic atoms, and in the latter case the …

    mit Repository record

  11. Shape optimization for thermoacoustic instability with an adjoint Helmholtz solver

    Falco, StefanoUniversity of Cambridge2021

    … system in the linear regime. We derive a Helmholtz equation with an unsteady heat release source and acoustic impedance boundary conditions. We apply the finite element method with P2 elements to discretize the weak formulation of the Helmholtz equation. We obtain a nonlinear eigenvalue …

    cambridge Repository record

  12. Sobre a teoria de regularidade elíptica via análise da equação de Helmholtz em RN

    Silva, Victor Rafael SantosUniversidade Federal do Rio Grande do Norte2022

    … present an important regularity result for the Helmholtz Equation in unbounded domains due to C. A. Stuart and, furthermore, we show that this result can also be used to regularize weak solutions of nonlinear elliptic problems in RN. In order to achieve our goals, it will be of vital importance …

    brazil-ufrn Repository record

  13. Radar scattering from bodies of revolution using an efficient partial differential equation algorithm

    Gordon, Richard KipUniversity of Illinois at Urbana-Champaign2011

    In this thesis, partial differential equation techniques for solving the problem of electromagnetic scattering by a three-dimensional body of revolution are discussed. The unknowns used do not obey the scalar Helmholtz equation. Thus, neither the Mur nor the Bayliss-Turkel boundary condition can be …

    uiuc Repository record

  14. Efficient Solution of Large Sparse Eigenvalue Problems in Microelectronic Simulation

    Galick, Albert ThomasUniversity of Illinois at Urbana-Champaign1993

    … model of quantum-effect devices, and the vector Helmholtz equation for a dielectric waveguide, addressing other important physical, numerical and computational issues as they arise. An asymptotic convergence estimate is derived which shows the Chebyshev-Arnoldi algorithm to be superior to …

    uiuc Repository record

  15. Mixed-Field Finite-Element Computations

    Sitapati, KartikVirginia Tech2004

    … is reached. The Direct method uses Maxwell's equations directly, both zero and first-order, scalar and vector bases that are used in the finite-element formulation. The direct solution method solves for both the magnetic and electric fields simultaneously. Comparisons are made with the …

    vt Repository record

  16. Domain partitioning to bound moments of differential equations using semidefinite optimization

    Sethuraman, SandeepMassachusetts Institute of Technology2006

    … on moments of solutions of linear differential equations. The motivation for change is to obtain tighter bounds by solving smaller semidefinite problems. The modification we propose involves partitioning the domain and normalizing each partition to ensure numerical stability. Using the adjoint …

    mit Repository record

  17. Numerical simulation of microwave heating of a target with temperature dependent electrical properties in a single-mode cavity

    Tran, Hoa Kien

    … varies. We then solve the coupled heat equation and Maxwell's equations to determine the history and distribution of the temperature in the ceramic sample. This complication increases the overall computational effort required by several orders of magnitude. In their work, Hile and …

    njit Repository record

  18. Flow -Induced Noise in Heat Exchangers

    Rodarte-Guajardo, EnriqueUniversity of Illinois at Urbana-Champaign2015

    … model was based on the inhomogeneous convected Helmholtz equation with a point dipole source term, volumetric damping and damping at the duct walls. The acoustic model was able to closely match the measured sound pressure field and the phase relationships between measurement points for sound …

    uiuc Repository record

  19. Electromagnetic field solutions via the finite element method

    Watkins, L RDepartment of Electrical Engineering1986

    … element method to the solution of two important equations which govern electromagnetic fields, namely, the Poisson equation and the Helmholtz equation. These equations. together with appropriate boundary conditions, describe boundary value and eigenvalue problems respectively. Attention will be …

    cape-town Repository record

  20. Reduced-basis output bound methods for parametrized partial differential equations

    Rovas, Dimitrios V. (Dimitrios Vasileios), 1975-Massachusetts Institute of Technology2003

    … of outputs of interest of partial differential equations with affine parameter dependence is presented. To achieve efficiency we employ the reduced-basis method: a weighted residual Galerkin-type method, where the solution is projected onto low-dimensional spaces with certain problem-specific …

    mit Repository record

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