 |
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 (Back On) ( 0 )
Related News Stories - (" Engineering ")
Swiss HCPVT Giant Photovoltaic 'Flower'
'...leaning against one of the slender stalks of a sunshade-photocell collector.'- David Brin, 1990.
Peel And Stick Thin Film Solar Cells
'It turns sunlight into electricity, just like any solar power converter, but you spray it on.'- Larry Niven, 1995.
Microbattery Extreme High Performance
'To this Foyle affixed a power pack the size of a pea and switched it on.'- Alfred Bester, 1956.
Speeding Ticket Robots To Cite Autonomous Cars?
'There is no danger of a vehicle's speed exceeding that allowed in the section in which it happens to be...'- John Jacob Astor IV, 1894.
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.
Current News
MIT Robot Cheetah Video Shows Gait Transition
'The legs are long, curled way up to deliver power, like a cheetah's.'
TrackingPoint Smart Rifle
Not your typical 'smart bullet' approach.
'Hello, Computer!' Google Now Highlighted at IO13
'Hello, computer!'
Sky City's 220 Stories Are Go
'It rested among green parklands and... stood in total isolation, a glittering block of whites and flashing windows dotted with colors.'
CARMAT Bioprosthetic Total Human Heart Replacement
'George Walt's corporate existence proved the workability of wholly mechanical organs...'
Personal Sniffer Robots
'...The ticking combinations of the olfactory system of the hound.'
Physical Exam? We've Got Apps
See the future of handheld, personal medical devices.
The Interplanetary Internet, Vint Cerf Speaking
'This was the center of Interplanetary Communications.'
Drosophila Robotica, The Mechanical Fly
'... the Scarab [flying robot] buzzed into the great workroom as any intruding insect might...'
Robo-Raven Flapping Wing Robot Bird
'When he had first built them, they had been crude indeed, flying mechanisms with little more than a reflex-response unit.'
Japan's Nursing Home Robot Plan
Let's make the Roujin Z-0001 Robotic Bed!
Samsung Smart TVs With Gesture Control
'He waved his hand and the circuit switched abruptly.'
Swiss HCPVT Giant Photovoltaic 'Flower'
'...leaning against one of the slender stalks of a sunshade-photocell collector.'
Mini-Livers Made By 3D Printer
Organleggers may experience an employment downturn.
Smartphone Sensor System Tracks Gunfire
'Sound trackers on the roof could zero in on weapons action...'
Bacteria Now Make Biofuel Like Oil
'They have ... germs that eat pretty near anything, and produce oil as a waste product.'
