Page 119 - Biomimetics: Technology Imitates Nature

Harun Yahya

noise levels must not ex-
ceed 75 decibels at a point
25 meters (82 feet) away
from the center of railway
track in urban areas. At a
crossing in a town, when
cars start to move all at
once on the green light,
they create more than 80
decibels. This goes to
show just how quiet the
high-speed Shinkansen
train must be. Serrations
The reason for the
noise that a train produces
up to a certain operation
speed is the rolling of its Pantograph
wheels on the tracks. At
speeds of 200 kmph (125
Owl feather
mph) or over, however,
the sound source becomes
the aerodynamic noise caused by its movement through the air.
The major sources of aerodynamic noise are the pantographs, or cur-
rent collectors, used to take in electricity from overhead catenary.
Engineers, realizing that they couldn’t reduce noise levels with the con-
ventional rectangular pantographs, concentrated their research on ani-
mals that move quickly, yet silently.
Of all birds, owls make the least noise during flight. One of the ways
they manage this is through the plumes of their wings. In addition, an
owl’s wings have many small saw-toothed feathers (serrations) visible

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