Group items tagged

"...scientists in Germany have built a device that can effectively make objects invisible to sound waves. The performance of the acoustic "invisibility cloak" exceeds that of existing electromagnetic devices and could open up new ways of manipulating waves, including the development of shields against seismic waves."

shit.... they are a few months ahead of us it seems ... :-( what is the impact on our ariadna??

Using little more than a few perforated sheets of plastic and a staggering amount of number crunching, Duke engineers have demonstrated the world's first three-dimensional acoustic cloak. The new device reroutes sound waves to create the impression that both the cloak and anything beneath it are not there.

Some cheating involved

Reminds me a bit of optical tweezers - although the principle seems somewhat different. Could the optical tweezers principle be applied through sound? http://en.wikipedia.org/wiki/Optical_tweezers

Researchers have proposed a new "acoustic topological insulator" that could help alleviate sound scattering problems by transmitting sound in certain directions without any backscattering.

If I understood correctly the triangular structure would channel the incident sound wave to a unique direction between two options, according to the rotation direction of the cylinders included in its mesh. So, one (possibly two) directions left to detect the hypothetical submarines? Very interesting though, I hope no oceanographers take measurements simultaneously to the signals as climate models will get even more wrong...!

An acoustic analogue of the dynamical Casimir effect (DCE) has been demonstrated for the first time.

Researchers in the US have made a "carpet cloak" that makes objects invisible to sound waves. The device is the first such cloak to work in air and could be used to improve the acoustics in concert halls or even to control unwanted noise.

Old news... Sante was doing this 10 years ago! And why does their metamaterial look like a pyramid?

According to Terry Pratchett pyramids affect the flow of time. Using this, any kind of cloaking device should be trivial.

This would be really cool, hawking radiation yeah !

Turns out you can do stuff with sound if you have enough of it.

The device, like dolphins, sends out two pulses in quick succession to allow for a targeted search for semiconductor devices, cancelling any background "noise",

Could it be used to measure ocean acidification? I found a study that links sound wave propagation with ocean acidity. Maybe we are able to do such measurement from space even? "Their paper, "Unanticipated consequences of ocean acidification: A noisier ocean at lower pH," published last week in the journal Geophysical Research Letters, found that fossil fuels are turning up the ocean's volume. Since the beginning of the Industrial Revolution, the overall pH of the world's oceans has dropped by about 0.1 units, with more of the changes concentrated closer to the poles. The authors found that sound absorption has decreased by 15 percent in parts of the North Atlantic and by 10 percent throughout the Atlantic and Pacific"

The last time I asked an oceanographer for the use of acoustic waves, she said it is still a bit problematic method to take into account its data, but we were referring to measuring ocean circulation. It may be more conclusive for PH measurements, though. The truth is that there is a whole underwater network with pulse emmitters/receivers covering the North Atlantic basin, remnant infrastructure for spying activities in the WW2 and in the cold war, that stays unexploited. We should look more into this idea

"Is music simply a pleasant accompaniment to thought, or a driving force behind it? This show examines music's influence on the development of modern science and the foundations of acoustics." See also http://www.nature.com/news/strike-a-chord-1.17127

we need more touch screens ...

Cool scientific and technical feat in engineering a tractor beam. See the explanation video here http://www.nature.com/ncomms/2015/151027/ncomms9661/extref/ncomms9661-s3.mov and the thing working in real time here http://www.nature.com/ncomms/2015/151027/ncomms9661/extref/ncomms9661-s2.mov