Science Fiction
Dictionary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 |
Bio Acoustic Fish Fence May Protect Great Lakes
A bio acoustic fish fence (BAFF) is being tested on a tributary about 200 miles from Chicago by ecologist Gregg Sass. The BAFF is basically an underwater sonic fence; a barrier created by outputting sounds into a wall of bubbles.
The intent is to stop invasive Asian carp species from swimming up the Illinois river and reaching the Great Lakes, which already have enough problems.
Physically, the BAFF comprises a pneumatic sound transducer coupled to a bubble-sheet generator, causing sound wave to propagate within the rising curtain of bubbles. The sound is contained within the bubble curtain as a result of refraction, since the velocity of sound in a bubble-water mixture differs from that in either water or air alone.
It uses an air bubble curtain to contain a sound signal which is generated pneumatically. Effectively, this creates a "wall of sound" (an evanescent sound field) field that can be used to guide fish around river structures by deflection into fish passes.
(An effervescent wall for fish)
1. Inside a shed on the riverbank, a signal generator emits eight chirps at varying intervals and varying frequencies up to 2,000 Hz. Two 400-watt amplifiers pump up the beeps to carp-deafening levels.
2. A compressor pushes a continuous stream of air through a rubber pipe riddled with small holes. The pipe, housed in an open steel chassis, runs across the bottom of the riverbed.
3. The pipe releases a sheet of bubbles illuminated by strobe lights flashing 200 to 400 times per minute. Alongside the pipe, 16 hundred-watt sound projectors shoot the chirping sounds into the fizz, where the noise is concentrated.
4. Native fish like trout and salmon can't hear frequencies above 400 Hz and swim through the bubbles unfazed. Carp, which perceive sound as high as 2,000 Hz, hit the piercing noise and turn back.
The first place I read about this idea was in Roger Zelazny's 1976 novel My Name is Legion; he refers to sonic curtains that can be used to keep sharks out of selected areas in underwater parks. Amusingly, dolphins can be taught to use it, and in turn teach other dolphins.
From Wired via Neatorama. See also this article on the fish fence.
Scroll down for more stories in the same category. (Story submitted 8/16/2009)
Follow this kind of news @Technovelgy.| Email | RSS | Blog It | Stumble | del.icio.us | Digg | Reddit |
Would
you like to contribute a story tip?
It's easy:
Get the URL of the story, and the related sf author, and add
it here.
Comment/Join discussion ( 0 )
Related News Stories - (" Engineering ")
Robotic Barber Programmed With a Number of Styles
'He found a barber shop which, he thought, would be good for an idle hour.' - Don Wilcox, 1939.
Centipede Robots Down On The Farm
'...the walking mills of Puffy Products began to tread delicately on their centipede legs across the wheat fields of Kansas.' - Fritz Leiber, 1958.
Vipera Electric Skis From Frigid Dynamics
'JOAN strapped on her power-skis...' - Ursula K. Le Guin, 1964.
Pivotal Blackfly Electric Aircraft Lifts And Hovers
'That explains how it was so easy for me to remain motionless in midair...' - RH Roman, 1929.
Technovelgy (that's tech-novel-gee!) is devoted to the creative science inventions and ideas of sf authors. Look for the Invention Category that interests you, the Glossary, the Invention Timeline, or see what's New.
Science Fiction
Timeline
1600-1899
1900-1939
1940's 1950's
1960's 1970's
1980's 1990's
2000's 2010's
Current News
Robotic Barber Programmed With a Number of Styles
'He found a barber shop which, he thought, would be good for an idle hour.'
Humanoid Boxing Robot KO's Opponent - It's A Knockout!
'Thirty rounds of fighting is tough work. Even for machines.'
Caterpillar Electric Mining Loader Not Yet Ready For Moon
'...the excavations were already in progress, for he saw gray slopes of rubble.'
Centipede Robots Down On The Farm
'...the walking mills of Puffy Products began to tread delicately on their centipede legs across the wheat fields of Kansas.'
Anthropic's Claude AI Creates Legal Citation From Whole Cloth
'Here is a Clerk that would work incessantly, and neither eat, sleep, want payment, or grumble.'
Students Vie For Lunar Regolith Mining Robot Prize
'About time you got here,' the astronaut said.
'They Erased My Memory' Says Ariana Grande
'...using a neutralizing electronic impulse.'
Solitary Black Hole Wanders In Space
'...the Hole is something like a vortex or a whirlpool?'
Spaceplane From Virgin Atlantic
'ZARNAK, YOU'RE TO COMMAND A SCOUTING EXPEDITION --- FIND OUT WHAT THIS IS ALL ABOUT!'
DARPA Wants 'Large Bio-Mechanical Space Structures'
'These are your rudimentary seed packages... Some will combine in place to form more complicated structures.'
Robot Hand Creeps Along, Separate From It's Owner
'The crawling... object was V-Stephen's surgeon-hand...'
Taikonauts Exercise In China's Tiangong Space Station
'Joe got out the gravity-simulator harnesses...'
Korean Exoskeleton Suit F1 Helps You Put It On
'Better late than never.'
Have AI Researchers Given Up On 'Bio-Babies'?
'You couldn't have the capstone without the pyramid to hold it up.'
Bunker Busters and Bore-Pellets
'The first revelation of the new Soviet bore-pellets.'
'Spikeless' Brand Swizzle Stick Detects Spiked Drinks
'the unobtrusive inspections with tiny remote-cast snoopers...'
