Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Mechanical Properties of Norway Spruce: Intra-Ring Variation and Generic
  Behavior of Earlywood and Latewood until Failure   The alternating earlywood and latewood growth ring structure has a strong
influence on the mechanical performance of Norway spruce. In the current study,
tensile tests in the longitudinal and tangential directions were performed on a
series of specimens representing one growth ring at varying relative
humidities. All tested mechanical parameters, namely modulus of elasticity and
ultimate tensile stress, followed the density distribution in the growth ring,
with the minimum values in earlywood and the maximum values in latewood. The
samples were conditioned at three the relative humidities 50%, 65% and 95%.
With increasing relative humidity, the values of the mechanical parameters were
found to decrease. However, due to the high local variability, this decrease
was not statistically significant. The test in the tangential direction on a
set of earlywood and latewood specimens at 65% relative humidity revealed a
similar limit of linear elasticity for both early- and latewood. Where the
strength of both tissues was equal, the strain at failure was significantly
greater for earlywood. Furthermore, the portion of the non-linear stress/strain
behavior for earlywood was significantly greater. A Weibull analysis on the
ultimate tensile strength revealed a tissue-independent Weibull modulus, which
indicates similar defect distributions. For both, the failure occurred in the
middle lamella.

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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: nlin
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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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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: q-alg
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The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph