Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scattering by coupled resonating elements in air   Scattering by (a) a single composite scatterer consisting of a concentric
arrangement of an outer N-slit rigid cylinder and an inner cylinder which is
either rigid or in the form of a thin elastic shell and (b) by a finite
periodic array of these scatterers in air has been investigated analytically
and through laboratory experiments. The composite scatterer forms a system of
coupled resonators and gives rise to multiple low frequency resonances. The
corresponding analytical model employs polar angle dependent boundary
conditions on the surface of the N-slit cylinder. The solution inside the slits
assumes plane waves. It is shown also that in the low-frequency range the
N-slit rigid cylinder can be replaced by an equivalent fluid layer. Further
approximations suggest a simple square root dependence of the resonant
frequencies on the number of slits and this is confirmed by data. The observed
resonant phenomena are associated with Helmholtz-like behaviour of the
resonator for which the radius and width of the openings are much smaller than
the wavelength. The problem of scattering by a finite periodic array of such
coupled resonators in air is solved using multiple scattering techniques. The
resulting model predicts band-gap effects resulting from the resonances of the
individual composite scatterers below the first Bragg frequency . Predictions
and data confirm that use of coupled resonators results in substantial
insertion loss peaks related to the resonances within the concentric
configuration. In addition, for both scattering problems experimental data,
predictions of the analytical approach and predictions of the equivalent fluid
layer approximations are compared in the low-frequency interval.

1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
18
The categories of this paper are: econ
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
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The categories of this paper are: comp-gas
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th