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      These scientists explored the good vibrations of the bundengan and didgeridoo

      news.movim.eu / ArsTechnica · Friday, 29 December - 21:28 · 1 minute

    Indonesian performers onstage with one playing a bundengan

    Enlarge / The bundengan (left) began as a combined shelter/instrument for duck hunters but it is now often played onstage. (credit: Utrezz0707/CC BY-SA 4.0 )

    There's rarely time to write about every cool science-y story that comes our way. So this year, we're once again running a special Twelve Days of Christmas series of posts, highlighting one science story that fell through the cracks in 2020, each day from December 25 through January 5. Today: the surprisingly complex physics of two simply constructed instruments: the Indonesian bundengan and the Australian Aboriginal didgeridoo (or didjeridu).

    The bundengan is a rare, endangered instrument from Indonesia that can imitate the sound of metallic gongs and cow-hide drums (kendangs) in a traditional gamelan ensemble. The didgeridoo is an iconic instrument associated with Australian Aboriginal culture that produces a single, low-pitched droning note that can be continuously sustained by skilled players. Both instruments are a topic of scientific interest because their relatively simple construction produces some surprisingly complicated physics. Two recent studies into their acoustical properties were featured at an early December meeting of the Acoustical Society of America, held in Sydney, Australia, in conjunction with the Australian Acoustical Society.

    The bundengan originated with Indonesian duck hunters as protection from rain and other adverse conditions while in the field, doubling as a musical instrument to pass the time. It's a half-dome structure woven out of bamboo splits to form a lattice grid, crisscrossed at the top to form the dome. That dome is then coated with layers of bamboo sheaths held in place with sugar palm fibers. Musicians typically sit cross-legged inside the dome-shaped resonator and pluck the strings and bars to play. The strings produce metallic sounds while the plates inside generate percussive drum-like sounds.

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      Myth, busted: Apatosaurus didn’t produce sonic booms when whipping its tail

      news.movim.eu / ArsTechnica · Thursday, 8 December, 2022 - 19:54 · 1 minute

    No sonic boom: Scientists created a computer simulation showing the tail movement of Apatosaurus . Credit: Simone Conti.

    Back in 1997, Microsoft's then-CTO, Nathan P. Myhrvold , made headlines when his computer simulations suggested that the enormous tails of sauropods—specifically Apatosaurus —could crack like a bullwhip and break the sound barrier, producing a sonic boom. Paleontologists deemed it an intriguing possibility, although several were skeptical. Now a fresh team of scientists has tackled the issue and built its own simulated model of an Apatosaurus tail. They found no evidence of a sonic boom, according to a new paper published in the journal Scientific Reports. In fact, the maximum speed possible in the new simulations was 10 times slower than the speed of sound in standard air.

    While still at Microsoft in the 1990s, Myhrvold—a longtime dinosaur enthusiast—stumbled upon a book by zoologist Robert McNeill Alexander speculating about whether the tails of certain sauropods may have been used like a bullwhip to produce a loud noise as a defensive strategy, a mating call, or other purpose. The structure somewhat resembles a bullwhip, in that each successive vertebra in the tail is roughly 6 percent smaller than its predecessor. It was already well-known in physics circles that the crack of a whip is due to a shock wave, or sonic boom, arising from the speed of the thin tip breaking through the sound barrier.

    Myhrvold wanted to put that speculative suggestion to the test, and struck up an email correspondence with paleontologist Philip J. Currie , now at the University of Alberta in Edmonton, Canada. (Fun fact: Currie was one of the inspirations for the Alan Grant character in Jurassic Park .) The two men analyzed fossils, developed computer models, and conducted several computer simulations to test the biomechanics of the sauropod's tail. They also compared those simulations to the mechanics of whips.

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      Fresh chemical clues emerge for the unique sound of Stradivari violins

      news.movim.eu / ArsTechnica · Thursday, 3 November, 2022 - 21:49 · 1 minute

    Violin against a red background.

    Enlarge / A 1729 Stradivari known as the "Solomon, Ex-Lambert" on display at Christie's in New York in March 2007. (credit: Don Emmert/AFP/Getty Images )

    Musicians and music aficionados alike have long savored the rich sound quality of the violins created by Antonio Stradivari , particularly at the dawn of the 18th century (the so-called " golden period "). Scientists have been equally fascinated by why Stradivari violins seem to sound so much better than modern instruments; it's been an active area of research for decades.

    A recent paper published in the journal Analytical Chemistry reported that nanoscale imaging of two such instruments revealed a protein-based layer at the interface of the wood and the varnish, which may influence the wood's natural resonance, and hence the resulting sound. Meanwhile, another paper published in the Journal of the Acoustical Society of America showed that the better resonance of older violins produces stronger combination tones, which can also affect the perception of musical tones.

    I've written extensively about this topic in the past, and you can read a handy summary of some of the research in this area to date here . Per my 2021 article , the (perceived) unique sound can't just be due to the instrument's geometry, although Stradivari's geometrical approach gave us the violin's signature shape. One hypothesis is that Stradivari may have used Alpine spruce that grew during a period of uncommonly cold weather, which caused the annual growth rings to be closer together, making the wood abnormally dense. Another popular theory has to do with the varnish: namely, that Stradivari used an ingenious cocktail of honey, egg whites, and gum arabic from sub-Saharan trees—or perhaps salts or other chemicals.

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      What it takes to re-create Rings of Power title sequence with Chladni figures

      news.movim.eu / ArsTechnica · Monday, 17 October, 2022 - 22:18 · 1 minute

    Steve Mould re-created The Rings of Power title sequence using patterns produced by vibrating square plates.

    The first time I saw the opening credits for The Lord of the Rings: The Rings of Power , I thought the patterns looked remarkably like so-called " Chladni figures ": vibrational patterns that form when one scatters sand on a vibrating plate. It seems I was not the only one. British science communicator and YouTube star Steve Mould got so many comments from viewers about the similarities that he decided to test that hypothesis—by re-creating the title sequence with his own vibration-generated patterns. He documents the journey, and the associated science, in the video above. The final re-created title sequence starts at the 10:55 mark.

    The phenomenon is technically known as cymatics . In 1680, Robert Hooke experimented with running a bow along glass plates covered in flour to induce vibrations and noted the telltale nodal patterns that formed in the flour.  "A rigid plate will have a set of natural resonance frequencies just like a string, and when the plate is excited at one of these frequencies, it will form a standing wave with fixed nodes," University of North Carolina physicist Greg Gbur wrote back in 2013 .  "These nodes will form lines on the plate, in contrast to points on the string." The flour on the plate made those nodal lines visible.

    The 18th century German physicist and musician Ernest Chladni perfected the method 100 years later when he repeated Hooke's pioneering experiments with circular plates, even demonstrating the effect before Napoleon. The various shapes or patterns created by resonance frequencies are known as "Chladni figures" in his honor. Chladni even came up with a mathematical formula to predict which patterns would form. The higher the rate of oscillation, the more complex those figures will be. Similar methods are still used when designing acoustic instruments: violins, guitars, and cellos, for example.

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      Qubits surf sound waves between quantum nodes

      news.movim.eu / ArsTechnica · Friday, 30 September, 2022 - 11:30

    Qubits surf sound waves between quantum nodes

    Enlarge (credit: Aurich Lawson / Getty Images)

    Inspired by the functioning of pulsed lasers, scientists from France and Japan have developed an acoustic counterpart that enables the precise and controlled transmission of single electrons between quantum nodes.

    Riding the waves

    The spin of an electron can serve as a basis for creating qubits—the basic unit of information of quantum computing. In order to process or store that information, the information in qubits may have to be transported between quantum nodes in a network.

    One option is transporting the electrons themselves, something that can now be done by having them ride sound waves. “More than 10 years ago, we demonstrated it for the first time,” said lead researcher Christopher Bauerle of the Grenoble-based Institute Néel .

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      This underwater camera operates wirelessly without batteries

      news.movim.eu / ArsTechnica · Thursday, 29 September, 2022 - 22:30 · 1 minute

    MIT engineers built a battery-free, wireless underwater camera that could help scientists explore unknown regions of the ocean, track pollution, or monitor the effects of climate change.

    Enlarge / MIT engineers built a battery-free, wireless underwater camera that could help scientists explore unknown regions of the ocean, track pollution, or monitor the effects of climate change. (credit: Adam Glanzman)

    MIT engineers have built a wireless, battery-free underwater camera, capable of harvesting energy by itself while consuming very little power, according to a new paper published in the journal Nature Communications. The system can take color photos of remote submerged objects—even in dark settings— and convey the data wirelessly for real-time monitoring of underwater environments, aiding the discovery of new rare species or monitoring ocean currents, pollution, or commercial and military operations.

    We already have various methods of taking underwater images, but according to the authors, "Most of the ocean and marine organisms have not been observed yet." That's partly because most existing methods require being tethered to ships, underwater drones, or power plants for both power and communication. Those methods that don't use tethering must incorporate battery power, which limits their lifetime. While it's possible in principle to harvest energy from ocean waves, underwater currents, or even sunlight, adding the necessary equipment to do so would result in a much bulkier and more expensive underwater camera.

    So the MIT team set about developing a solution for a battery-free, wireless imaging method. The design goal was to minimize the hardware required as much as possible. Since they wanted to keep power consumption to a minimum,  for instance, the MIT team used cheap off-the-shelf imaging sensors. The trade-off is that such sensors only produce grayscale images. The team also needed to develop a low-power flash as well, since most underwater environments don't get much natural light.

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