Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fractal design for an efficient shell strut under gentle compressive
  loading   Because of Euler buckling, a simple strut of length $L$ and Young modulus $Y$
requires a volume of material proportional to $L^3 f^{1/2}$ in order to support
a compressive force $F$, where $f=F/YL^2$ and $f\ll 1$. By taking into account
both Euler and local buckling, we provide a hierarchical design for such a
strut consisting of intersecting curved shells, which requires a volume of
material proportional to the much smaller quantity $L^3 f\exp[2\sqrt{(\ln
3)(\ln f^{-1})}]$.

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The categories of this paper are: q-alg
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: supr-con
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The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th