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Nature and Technology Design

Green Country Vol. 125 (Apr 2017)

Flying birds, diving fish, butterflies that journey for miles… Natural wonders have inspired humans for centuries. Birds' flight served as a blueprint for the invention of airplane. Radar communication systems were based on the ultrasound echoes of bats and dolphins. Amazing nature will continue to stimulate and enrich our civilisation.

Bullet Train and Kingfisher

Japan has one of the most sophisticated railway networks in the world, including the high-speed railway system Shinkansen that's nicknamed “bullet train”. While providing much convenience, the high-speed railway also resulted in a noise problem. As a train enters a tunnel, a pressure wave is formed as the air surrounding the train cannot be dispersed in time, leading to a “tunnel boom" at the exit and causing a problem for nearby residents. The problem was only solved in the 1990s. Eiji Nakatsu, a Japanese engineer and a bird watching enthusiast, noticed that a Kingfisher makes no splash as it dashes into water for fish. He then designed a new nose cone for the bullet train, based on the shape of the Kingfisher's beak, to reduce wind drag. This solved the noise problem, as well as saving 15% of energy and raising the train speed.

Fan Blade and Humpback Whale

Dr. Frank Fish, a biologist from the West Chester University of Pennsylvania, once picked up a Humpback Whale (Megaptera novaeangliae) model in a souvenir shop, and noted the many bumps across the leading edges of the flippers, which are called “tubercles”. He launched some studies and found that these tubercles could reduce water drag and create turbulent vortices, allowing the giant Humpback Whale to swim with ease through water. Based on the new findings, the research team invented fans with serrated blades, which saved up to 20% of energy compared to conventional fans. This technique was later applied in wind turbine designs, to raise the efficiency of wind power generation.

Self-cleaning Materials and Lotus

As early as in the Northern Song Dynasty, philosopher Zhou Dunyi admired the self-cleaning ability of Lotus (Nelumbo nucifera). Today, after almost a millennium, scientists are studying the property. Under a microscope, one can see that the Lotus leaf surface is not smooth. Instead it has a coating of nano-size wax crystals, which is superhydrophobic. When water flows across the leaf surface, any dust on it is carried away, making the surface self-cleaning. Based on this property, a variety of self-cleaning materials such as paint and glass have been invented. With these inventions, buildings can be self-cleaned in rain, reducing the need for artificial cleaning and cleaning agents.

Text | Hayward Ng

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Photo from Pixabay
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© Henry Lui
The bullet train nose cone is designed to mimic a Kingfisher's beak, to reduce noise and save energy.
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© WhalePower Corporation
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Serrated blades can effectively reduce wind drag. The design was based on the tubercles on the leading edges of the Humpback Whale flippers
Photo from Pixabay
Image
© Hayward Ng
Self-cleaning materials were inspired by the same characteristic of Lotus.

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