Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Energy conversion in isothermal nonlinear irreversible processes -
  struggling for higher efficiency   First we discuss some early work of Ulrike Feudel on structure formation in
nonlinear reactions including ions and the efficiency of the conversion of
chemical into electrical energy. Then we give some survey about energy
conversion from chemical to higher forms of energy like mechanical, electrical
and ecological energy. We consider examples of energy conversion in several
natural processes and in some devices like fuel cells. Further, as an example,
we study analytically the dynamics and efficiency of a simple "active circuit"
converting chemical into electrical energy and driving currents which is
roughly modeling fuel cells. Finally we investigate an analogous ecological
system of Lotka - Volterra type consisting of an "active species" consuming
some passive "chemical food". We show analytically for both these models that
the efficiency increases with the load, reaches values higher then 50 percent
in a narrow regime of optimal load and goes beyond some maximal load abrupt to
zero.

0
The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph