Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Synchrophasor monitoring of single line outages via area angle and
  susceptance   The area angle is a scalar measure of power system area stress that responds
to line outages within the area and is a combination of synchrophasor
measurements of voltage angles around the border of the area. Both idealized
and practical examples are given to show that the variation of the area angle
for single line outages can be approximately related to changes in the overall
susceptance of the area and the line outage severity.

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The categories of this paper are: quant-ph
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The categories of this paper are: supr-con
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: stat
20
The categories of this paper are: acc-phys
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The categories of this paper are: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: hep-lat
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The categories of this paper are: funct-an
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The categories of this paper are: nlin
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The categories of this paper are: physics