Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An Investigation of Natural Gas as a Substitute for Diesel in Heavy Duty
  Trucks and Associated Considerations   In this paper, applicability of natural gas fuel for transportation as
compared to diesel is investigated. This study investigates a promising
technology for the heavy duty truck sector of transportation as a target for
conversion from diesel to natural gas. The supply of natural gas is limited so
we also verify the available domestic supply quantities both before and after a
fleet conversion. This paper concludes with an economic discussion regarding
Javon's paradox and the fungibility of natural gas as compared to that of oil.
In order to determine if natural gas can replace diesel for the country's heavy
duty truck transportation needs, the energy equivalent and efficiency of
natural gas alternatives should be compared to diesel. There are two
alternatives for using natural gas as a replacement for diesel; compressed
natural gas and liquefied natural gas.

20
The categories of this paper are: acc-phys
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
22
The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio
11
The categories of this paper are: hep-lat