Invention: Spy-diver killer
16:05 10 January 2006
NewScientist.com news service
For over 30 years, Barry Fox has trawled the world's weird and wonderful patent applications each week, digging out the most exciting, intriguing and even terrifying new ideas. His column, Invention, is exclusively online. Scroll down for a roundup of previous Invention articles.
If you are scuba diving, be sure not to swim anywhere near any ship or installation that has been protected by the Raytheon Corporation's new "swimmer denial" system. Otherwise you will very quickly feel extremely sick and probably drown.
Raytheon’s underwater sensors detect any unwelcome presence and trigger an underwater sound system that emits extremely powerful pulses of low frequency audio. The pulse rate and audio frequency are chosen to make human organs resonate like organ pipes, causing swimmers to vomit into their masks or suffer internal ruptures.
The idea of blasting very powerful sound at underwater targets is not new. It can even be used to detonate incoming torpedoes. But it can also cause havoc with marine life.
Raytheon's new system is "greener" because the main sound projector, in the middle of the secure zone, emits sounds with power and frequency that are relatively safe. A dozen or so secondary projectors in a ring round the zone also emit safe pulses. But in the region near each secondary projector the main and secondaries combine to produce a sound which is decidedly dangerous.
Would-be spies or terrorists cannot get through the ring but there is no widespread danger to fish, dolphins or whales.
Read Raytheon's secrets, here.
Think of two really annoying things about word processing and printing. Static electricity makes printers jam because the paper sticks together and typing up a sheet of notes involves trying to balance or clip the paper upright.
Two German inventors from Bayreuth, Brian Schlede and Stefan Krug, have put the two nuisances together and come up with a battery-powered stand for paper that uses static electricity to hold the paper in place.
The upright stand is a like a picture frame, with an aluminium metal sheet sandwiched between two thin plastic films. A transformer feeds a few hundred volts at safe low current into the aluminium, to give it a static charge. The plastic film prevents shock but when a sheet of paper is laid over the sandwich it sticks.
The patent filing is a useful reminder that sometimes the best ideas are sometimes the simple ones.
Read the original text (pdf in German) here.
The capacity of hard drives can be pushed to over 1 terabit of data per square inch, says Seagate in California. Increasing the data density can be done by shrinking the size of the magnetic spots that record the data – the tricky bit is that the tiny magnetic spots are so small that their magnetism fades soon after recording.
The solution is to heat a spot of the disc surface just before it is magnetised by the recording head. As the hot spot cools it stores a stronger signal. A laser beam can do the heating, but it would have to be focused on a 20-nanometre-wide spot which is impractical with affordable optics.
Seagate's solution is to pre-heat a larger area of the disc surface with a largish spot, then boost the heat in a tightly defined area and hit it with a magnetic pulse. A superfine gold electrode channels a powerful electromagnetic field down onto the surface - like a lightning rod - to superheat the 20 nm spot.
The electrode has a 50-nanometre-square cross section that tapers to a ultra-sharp needlepoint near an ordinary magnetic recording head. The heating process does not slow the data writing speed because the thin magnetic surface of the disc heats very quickly just before the magnetic pulse is applied.
Read the finer details of Seagate’s fine-spot recording system, here.