Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The many avatars of Curzon-Ahlborn efficiency   Efficiency at maximum power output of irreversible heat engines has attracted
a lot of interest in recent years. We discuss the occurance of a particularly
simple and elegant formula for this efficiency in various different models. The
so-called Curzon-Ahlborn efficiency is given by the square-root formula:
$1-\sqrt{T_c/T_h}$, where $T_c$ and $T_h$ are the cold and hot reservoir
temperatures.

8
The categories of this paper are: hep-ex
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
1
The categories of this paper are: cs