Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Sources of UHECRs in view of the TUS and JEM-EUSO experiments   The origin of ultra-high-energy cosmic rays (UHECRs) is one of the most
intriguing problems of modern cosmic ray physics. We briefly review the main
astrophysical models of their origin and the forthcoming orbital experiments
TUS and JEM-EUSO, and discuss how the new data can help one solve the
long-standing puzzle.

33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
25
The categories of this paper are: patt-sol
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
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The categories of this paper are: comp-gas
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The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th