From economic trends, population growth, the spread of cancer, or the adoption of new technology, certain patterns inevitably seem to emerge. A new technology, for example, begins with slow acceptance, followed by explosive growth, only to level off before "hitting the wall."
When plotted on graph, this pattern of growth takes the shape of an "S."
While this S-curve has long been recognized by economists and scientists, a Duke University professor believes that a theory he developed explains the reason for the prevalence of this particular pattern, and thus provides a scientific basis for its appearance throughout nature and the man-made world.
"This phenomenon is so common that it has generated entire fields of research that seem unrelated – the spread of biological populations, chemical reactions, contaminants, languages, information and economic activity," said Adrian Bejan, engineering professor at Duke's Pratt School of Engineering. "We have shown that this pattern can be predicted entirely as a natural flow design."
The concept of flow design, whether it be energy, rivers or human populations, is central to Bejan's theory.
The results of this theory of the S-curve, conducted with collaborator Sylvie Lorente from the University Toulouse, France, were published online in the Journal of Applied Physics. The research was supported by the National Science Foundation, the U.S. Air Force Office of Scientific Research and the National Renewable Energy Laboratory.
Bejan's theory, known as the constructal law, is based on the principle that flow systems evolve their designs over time to facilitate flow access, reducing and distributing friction or other forms of resistance. Bejan developed the principle 15 years ago, and has been using it to describe and predict a wide variety of man-made and natural phenomena.
The current analysis views this ubiquitous S-curve (also known as the sigmoid function) as a natural design of flow systems. In the example of a new technology, after a slow initial acceptance, the rise can be imagined moving fast through established, though narrow, channels into the market place. This is the steep upslope of the "S."
As this technology matures, and its penetration slows, any growth, or flow, moves outward from the initial penetration channels in a shorter and slower manner. Bejan likes to the use metaphor of fingers stretching out to represent the initial invasive growth, with the placement of a glove over those fingers as a representation of the lateral consolidation phase.
"It's like there are two lives – the first is long and fast, while the second phase is short and slow," Bejan said. "The trend begins with a quick 'invasion,' followed by a 'slower' consolidation. Then the trend hits a wall."
This pattern matches that of the constructal theory, which uses a large river basin as a visual description of flow systems, growing fast and far, with smaller branches growing laterally from the main channels.
"The prevalence of the S-curve phenomena in nature rivals that of the tree-shaped flows, which also unite the animate, inanimate and human realms," Bejan said. "This theory shows that this is not a coincidence – both are manifestations of the natural constructal tendency of flow systems to generate evolving designs that allow them to flow, spread and collect more easily."
Richard Merritt | EurekAlert!
NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center
Researchers create artificial materials atom-by-atom
28.03.2017 | Aalto University
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
29.03.2017 | Health and Medicine
29.03.2017 | Earth Sciences
29.03.2017 | Trade Fair News