Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Perturbation theory of thermal rectification   Thermal rectification which is a diode-like behavior of heat flux has been
studied over a long time. However, a universal and systematic physical
description is still lacking. In this letter, a perturbation theory of thermal
rectification is developed, which provides an analytical formula of the thermal
rectification ratio. It reveals the linear relationship between the thermal
rectification ratio and temperature difference. Furthermore, the
size-dependence of the thermal rectification relies on the specific form of the
thermal conductivity. In addition, several experimental and numerical
observations in previous literatures are well explained. This theory can be
applicable to any system in which a differentiable effective thermal
conductivity can be derived, and is helpful to unveil general principle for
thermal rectification.

25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
27
The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
8
The categories of this paper are: hep-ex
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio