Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spatial Filtering of Sound Beams by Sonic Crystals   We propose and numerically demonstrate an efficient cleaning of spatial
structure (spatial filtering) of sound beams by propagating them through at
least twodimensional sonic crystals, i.e. through acoustic structures
periodically modulated in longitudinal and in transversal direction with
respect to the sound propagation direction. We show the spatial filtering in
two configurations: with- and without the angular band-gap. We also show that
besides the spatial filtering the beams can be additionally focalized at a
particular distance behind the sonic crystal in both configurations.

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The categories of this paper are: acc-phys
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The categories of this paper are: solv-int
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The categories of this paper are: econ
12
The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-th
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The categories of this paper are: chem-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: cs
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: bayes-an