Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Acoustic Performance of Micro-Grooved Elements   The acoustic performance of a new type of fibre-less sound absorber, the
micro-grooved element (MGE), is studied in this paper. A MGE is a double layer
element that involves inlet/outlet slots and inner micro-channels engraved onto
the mating surface of the layers. MGEs are potential substitute of traditional
micro-perforated elements (MPEs) in applications where the absorption
coefficient, the acoustic behaviour at high levels of sound excitation and the
cost of the absorber are of main concern.
  The transfer impedance and the absorption coefficient of MGEs and MPEs are
measured, modelled and compared in this study. The acoustics of the
micro-channels is treated in detail, the impedance end corrections are
determined and the non-linear effects are accounted for. The linear behaviour
of MGEs is described by extending the models for slit-shaped perforated
elements. The quasi- and non- linear behaviours are expressed as a function of
the Shear number and Strouhal number by curve fitting the experimental results.

6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
19
The categories of this paper are: eess
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
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The categories of this paper are: nlin
15
The categories of this paper are: nucl-ex