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Adaptation and optimality of biological structures.
The amazing rationality of biological ``constructions'' calls
for the use of structural optimization methods.
Consider, for example, a bone: It is a mechanical structure made of
composites with variable parameters that adapts itself to its working conditions.
It performs a clearly described mechanical task of supporting the organism.
These features are similar to such man-made composite structures as masts,
bridges, towers, and domes. Therefore, it would be natural to apply optimization
methods developed for engineering constructions to bone structures, as
it has been done in the papers by
However, the two problems are not the same.
Firstly, the natural "optimized designs" satisfy certain restrictions
which
arew not too easy to formalize:
-
Nature does not necessarily looks for a global minimum, but may settle
for a local minimum.
-
A biological structure results from stable evolutionary dynamics.
-
A biological structure possess certain randomness
-
Structure must be extremely roboust.
Secondly, it is not clear what quantity is minimized
in
natural evolutionary biomaterials (we mean the explicit optimality criterion
of a natural structure, not a general reference to the evolution that perfects
organisms).
In engineering problems, the goal is the minimization of a given functional
that is not the subject of a search or even a discussion. The problem is
to find the structure that minimizes a functional prescribed by a designer.
Contraty to this, the structure of a bone is known, but it is not clear
in what sense (if any) the bone structure is optimal.
Investigation of optimality of evolutionary objects leads to the search
for a cost functional of an optimization problem with a known solution.
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