نتایج جستجو برای: helmholtz

تعداد نتایج: 6388  

Journal: :Proceedings of the National Academy of Sciences 2019

Journal: :International Journal of Thermophysics 2013

Journal: :Bulletin of the American Mathematical Society 1906

Journal: :Math. Comput. 2017
Ivan G. Graham Eugene A. Spence Eero Vainikko

In this paper we give new results on domain decomposition preconditioners for GMRES when computing piecewise-linear finite-element approximations of the Helmholtz equation −∆u − (k2 + iε)u = f , with absorption parameter ε ∈ R. Multigrid approximations of this equation with ε 6= 0 are commonly used as preconditioners for the pure Helmholtz case (ε = 0). However a rigorous theory for such (so-ca...

2014
Andrei Fursikov Mark Iosifovich Vishik A. V. FURSIKOV

The simplest parabolic equation of normal type with periodic boundary condition is considered, and the problem of stabilization to zero of its solution with arbitrary initial condition by starting control supported in a prescribed subset is investigated. This problem is reduced to one inequality for starting control, and the proof of this inequality is given. Introduction. This paper is devoted...

2010
H.-W. Chang S.-Y. Mu

The frequency-domain finite-difference (FD-FD) methods have been successfully used to obtain numerical solutions of the twodimensional (2-D) Helmholtz equation. The standard second-order accurate FD-FD scheme is known to produce unwanted numerical spatial and temporal dispersions when the sampling is inadequate. Recently compact higher-order accurate FD-FD methods have been proposed to reduce t...

1998
Xiaodong Wang Zhigang Feng

In this paper, we present an analytical expression for the resonance frequency of Helmholtz attenuators with air cavity and membrane. We derive the characteristic equations based on one-dimensional isentropic acoustic models and illustrate the eeects on the resonance frequency of certain design variations. 1 INTRODUCTION The development of high speed paper machines requires a better control of ...

Journal: :Journal of Fluid Mechanics 2019

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