Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultra-thin Underwater Acoustic Metasurface with Multiply Resonant Units   This paper describes a new kind of acoustic metasurface with multiply
resonant units, which have previously been used to induce multiple resonances
and effectively produce negative mass density and bulk/shear moduli. The
proposed acoustic metasurface can be constructed using real materials and does
not rely on an ideal rigid material. Therefore, it can work well in a water
background. The thickness of the acoustic metasurface is about two orders of
magnitude smaller than the acoustic wavelength in water. The design of a unit
group is proposed to avoid the phase discretization becoming too fine in such a
long-wavelength condition. We demonstrate that the proposed acoustic
metasurface achieves good performance in anomalous reflection, focusing, and
carpet cloaking.

19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math