Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Characterization of welding defects by fractal analysis of ultrasonic
  signals   In this work we apply tools developed for the study of fractal properties of
time series to the problem of classifying defects in welding joints probed by
ultrasonic tecniques. We employ the fractal tools in a preprocessing step,
producing curves with a considerably smaller number of points than in the
original signals. These curves are then used in the classification step, which
is realized by applying an extension of the Karhunen-Loeve linear
transformation. We show that our approach leads to small error rates,
comparable with those obtained by using more time-consuming methods based on
non-linear classifiers.

1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
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The categories of this paper are: stat
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
23
The categories of this paper are: solv-int
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The categories of this paper are: adap-org