Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Numerical simulations of diffusive shock acceleration in SNRs   A new numerical model of the nonlinear diffusive shock acceleration is
presented. It is used for modeling of particle acceleration in supernova
remnants. The model contains coupled spherically symmetric hydrodynamic
equations and the transport equations for energetic protons, ions and
electrons. The forward and reverse shocks are included in the consideration.
The spectra of cosmic rays released into interstellar medium from a supernova
remnant are determined. The role of the reverse shock in the production of CR
ions and positrons is discussed.

28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
1
The categories of this paper are: cs
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex