Sunday, March 9, 2014

Fractals and Its Application to Science and Technology


Frost crystals formed and established their behavior through fractals


There are some spatial patterns of nature can be described through classical geometry, but most of these patterns are irregular and doesn’t have an organized property; for instance, the leaves of a certain flower. These patterns thus cannot be interpreted geometrically and thus can be described through the use of a family of curves which are called fractals.

The word “fractal” can be associated by the words “irregular” or “fragmented”, according to its Latin etymology – the adjective “fractus”. Mathematically, fractals are a set of curves displaying a self-similar pattern, that is, it is the same pattern as it is enlarged and also as it is reduced. Fractals can be described through mathematical equations which are nowhere differentiable.

The history of fractals comes from the work of the mathematicians about “self-similarity”. In 17th century, Gottfried Leibniz first studied recursive self-similarity and used the term “fractional exponents”, in which he admitted that it was impossible to describe this using (classical) geometry. In 1872, Karl Weierstrass studied and presented some functions whose graphs are everywhere continuous but nowhere differentiable, which are considered nowadays to be fractals. In the last part of that century, Georg Cantor, Felix Klein and Henri Poincare developed some properties of fractals; one of them can be categorized as “self-inverse” fractals. Later, in the 20th century, more mathematicians became interested on fractals and they gave their respective versions for it, such as Koch curve and Levy C curve. The term “fractals” was then coined by Benoit Mandelbrot in 1975 through the use of computer graphics in his presentations.

From the definition itself, fractals possess self-similar patterns. Another characteristic of fractals is that they give detailed patterns for arbitrarily smaller (or larger) scales. It is also irregular (not differentiable everywhere in mathematical sense), simple, and can be defined through recursion, that is, the unknown values can be found through the previous results.

As fractals can be described through computer graphics, many things in nature can be approximately associated with fractals, because they appear more irregular in form. Furthermore, fractals are always intertwined with chaos, because fractals depict chaotic behavior. Some examples of these things in nature which are fractals are cumulus clouds, the veins in a hand, the DNA molecule, the oxygen molecule, the leaves in a tree, and the like.

Fractals have many applications in science and technology. One purpose of studying fractals is to predict patterns that are seemingly random. For instance, weather forecasters use fractal geometry to understand cloud formations, ocean currents and air currents so that they can predict the weather for a particular place on a particular day. Fractals can be used to model soil erosion, as well as seismic patterns in earthquakes. In fluid mechanics, turbulence flows can be described through fractals, which is helpful for engineers to understand complex flows.  In computer science, a certain kind of compression known as the fractal image compression is used to describe the world through fractal geometry (which can be seen through JPEG or GIF images). Fractals can be also used in medicine, geology, geography, and others.


References:

[1] Kluge, Tino et.al., (2000), Fractals in nature and applications. Fractals and Dynamic Systems. Retrieved from http://kluge.in-chemnitz.de/documents/fractal/project.html

[2] Fractal. Wikipedia. Retrieved from http://en.wikipedia.org/wiki/Fractal

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