scholarly journals Detecting inclusions with a generalized impedance condition from electrostatic data via sampling

2019 ◽  
Vol 42 (18) ◽  
pp. 6741-6756
Author(s):  
Isaac Harris
Keyword(s):  
Impedance Condition

MATHEMATICAL ANALYSIS OF THE ACOUSTIC DIFFRACTION BY A MUFFLER CONTAINING PERFORATED DUCTS

2005 ◽  
Vol 15 (07) ◽  
pp. 1059-1090 ◽  
Author(s):  
A. S. BONNET-BEN DHIA ◽  
D. DRISSI ◽  
N. GMATI
Keyword(s):  
Three Dimensional ◽  
Two Dimensions ◽  
Scalar Problem ◽  
Fredholm Type ◽  
Numerical Examples ◽  
Time Harmonic ◽  
Impedance Condition ◽  
Absorbing Material ◽  
Acoustic Diffraction ◽  
Theoretical Results

We consider the three-dimensional scalar problem of acoustic propagation in a muffler. We develop and analyze a Fredholm-type formulation for a stationary fluid in the time-harmonic setting. We prove a homogenization result for a muffler containing periodically perforated ducts. Essentially, the perforated boundaries become completely transparent when the period of perforations, which is assumed to be of the same order as the size of perforations, tends to zero. We also derive a homogenized impedance condition when the perforated duct is coated by an absorbing material. We present numerical examples in two dimensions, obtained from coupling finite elements in the muffler with modal decompositions in the inlet and outlet ducts, which demonstrate the limiting validity of the theoretical results.

scholarly journals On hearing the shape of an arbitrary doubly-connected region in R2

1990 ◽  
Vol 31 (4) ◽  
pp. 472-483 ◽  
Author(s):  
E. M. E. Zayed
Keyword(s):  
Asymptotic Expansion ◽  
Spectral Function ◽  
Basic Problem ◽  
Outer Boundary ◽  
Connected Region ◽  
Two Dimensional ◽  
Complete Knowledge ◽  
Impedance Condition

AbstractThe basic problem in this paper is that of determining the geometry of an arbitrary doubly-connected region in R2 together with an impedance condition on its inner boundary and another impedance condition on its outer boundary, from the complete knowledge of the eigenvalues for the two-dimensional Laplacian using the asymptotic expansion of the spectral function for small positive t.

scholarly journals Direct numerical simulation of turbulent flow with an impedance condition

2015 ◽  
Vol 344 ◽  
pp. 28-37 ◽  
Author(s):  
Simone Olivetti ◽  
Richard D. Sandberg ◽  
Brian J. Tester
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flow ◽  
Impedance Condition

Generalized Fourier Transform for Stratified Media

1972 ◽  
Vol 50 (24) ◽  
pp. 3123-3131 ◽  
Author(s):  
E. Bahar
Keyword(s):  
Electromagnetic Theory ◽  
Observation Point ◽  
Propagation Path ◽  
Stratified Media ◽  
Generalized Fourier Transform ◽  
Scalar Wave ◽  
Exact Boundary ◽  
Impedance Condition ◽  
Fourier Type ◽  
Infinite Media

A Fourier-type transform is derived for functions satisfying the scalar wave equation in stratified media. Using this transform, the function is expressed as a sum of two infinite integrals and a discrete term. In electromagnetic theory, the infinite integrals correspond to the radiation and the lateral wave terms and the discrete term corresponds to the surface wave.The transform provides a suitable basis for the expansion of electromagnetic fields when the height of the interface between two semi-infinite media and their electromagnetic parameters vary along the propagation path. Exact boundary conditions are employed here rather than the restricted surface impedance condition. The expansion is particularly appropriate for problems in which the source and the observation point are not in the same medium.

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