Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Increasing the Efficiency of Energy Scavengers   In this paper, a methodology for designing efficient energy scavengers is
proposed. The scavenger consists of a cantilever beam on which piezoelectric
films and a mass are mounted. The mass at the tip of the beam is known as the
proof mass and the device is called either an energy scavenger or a beam-mass
system. The proof mass is a permanent magnet, where in its vicinity attracting
permanent magnets are placed. It is shown that when the magnets have
appropriate strengths and are placed appropriately, the vibration of the
beam-mass system can be amplified, thereby the scavenged energy is increased.
Examples are given throughout the paper.

24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
8
The categories of this paper are: hep-ex
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th