Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Caract\'erisation de r\'eacteurs photocatalytiques utilis\'es pour le
  traitement de l'air   Photocatalysis is often used in air purification. Photocatalytic degradation
od VOC's has been investigated in a number of devices. An optimisation of this
process requires a chracterisation of the reactor : in a first step the gas
flow behaviour has to be studied (plug flow, CSTR,...) by RTD analysis; then,
chemical kinetics have to be determined as a function ot the relevant
parameters (space time, relative humidity, concentrations, etc). All the data
collected lead to a reliable design of the equipment.

31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th