Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Mechanical Rainbow Trapping and Bloch Oscillations in Structured Elastic
  Beams
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
26
The categories of this paper are: bayes-an
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex