Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Building the Space Elevator: Lessons from Biological Design   One of the biggest perceived challenges in building megastructures, such as
the space elevator, is the unavailability of materials with sufficient tensile
strength. The presumed necessity of very strong materials stems from a design
paradigm which requires structures to operate at a small fraction of their
maximum tensile strength (usually, 50% or less). This criterion limits the
probability of failure by giving structures sufficient leeway in handling
stochastic components, such as variability in material strength and/or external
forces. While reasonable for typical engineering structures, low working stress
ratios --- defined as operating stress as a fraction of ultimate tensile
strength --- in the case of megastructures are both too stringent and unable to
adequately control the failure probability. We draw inspiration from natural
biological structures, such as bones, tendons and ligaments, which are made up
of smaller substructures and exhibit self-repair, and suggest a design that
requires structures to operate at significantly higher stress ratios, while
maintaining reliability through a continuous repair mechanism. We outline a
mathematical framework for analysing the reliability of structures with
components exhibiting probabilistic rupture and repair that depend on their
time-in-use (age). Further, we predict time-to-failure distributions for the
overall structure. We then apply this framework to the space elevator and find
that a high degree of reliability is achievable using currently existing
materials, provided it operates at sufficiently high working stress ratios,
sustained through an autonomous repair mechanism, implemented via, e.g.,
robots.

22
The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
18
The categories of this paper are: econ
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
13
The categories of this paper are: quant-ph
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con