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 ")
Wolfram Alpha Mathematica Predicted by Science Fiction in 1948!
'The answer to the dumb student's prayer.' - Margaret St. Clair, 1948
Special Lights For Driverless Cars!
'That light is actually the Anamorphic Equalizer...'
'Old People Began to Cross The Continent In Their Own Cars'
'It was a relief to enter one of the comfortable autos, whisper a direction down the tube, and just know that you would be taken to your destination in the quickest, safest, and cheapest manner.' - Dr. David H. Keller, 1935.
Biomimetic Tendons From Rochu Robotics
'... the curious parallelism to animal motions.' - HG Wells, 1898.
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
Wolfram Alpha Mathematica Predicted by Science Fiction in 1948!
'The answer to the dumb student's prayer.'
Cislunar Space And The Space Lanes of Golden Age Science Fiction
'He had travelled the space-lanes of the solar system for the greater part of his life...'
NASA Moonbase Update
'The dinner was excellent. It was completely vegetarian — grown in specially prepared gardens in this Moon base...'
Neuralink Will Allow Humans To Communicate With ... Animals?
'Telepaths had their sensitiveness enlarged to an immense range by the pin-sets, which were telepathic amplifiers adapted to the mammal mind.'
Special Lights For Driverless Cars!
'That light is actually the Anamorphic Equalizer...'
'Old People Began to Cross The Continent In Their Own Cars'
'It was a relief to enter one of the comfortable autos, whisper a direction down the tube, and just know that you would be taken to your destination in the quickest, safest, and cheapest manner.'
Harrison Bergeron, Illustrated And Practiced
'But he didn't get very far with it before another noise in his ear radio scattered his thoughts. George winced...'
Starfall Manufacturing Drugs In Space
'The vast spinning sphere of Factory in the Sky loomed above and ahead of us, gleaming white against the unfathomable jet depths of surrounding space.'
The Solar Oberth Slingshot
'And if it doesn’t work,' inquired Lazarus, 'what does that make us? Sunspots?'
'Maybe The Woman Of Your Life Is Still Under Production'
'The Dillard people had performed a miracle and put all the works in a girl-modeled case.'
'If Anyone Is Watching Earth...'
'Our study of your race has convinced us that you are not fitted to leave your planet in the present state of your civilization.'
Epirus High-Power Microwave Defeats Drones
'...the spreading beam of the deranging ray struck them, and Then one toppled and fell. Then another.'
Cloud Of Space Rubbish From China's Long March Rocket
'Within seconds the material was spread out over fifty yards, in a matter of hours it might occupy several cubic miles of space...'
Biomimetic Tendons From Rochu Robotics
'... the curious parallelism to animal motions.'
Living Human Neuron Biological Compute Rack
'The men are dead, but their acquired wisdom lives on and I am the beneficiary.'
Martha Stewart Approves Ojai 'Living Room On Wheels'
'Young people found the driverless car admirable for petting.'
