We've heard a lot about how someday metamaterials -- composites that bend electromagnetic waves in bizarre ways -- could lead to invisibility cloaks. Also in the lab are acoustic cloaks that bend sound waves to hide objects underneath. Researchers from Duke University have just reported on their success making a small acoustic cloak that works in air, not just water as has already been demonstrated. Eventually, the metamaterial could be used to tweak acoustics in concert halls at a very high resolution or hide submarines from sonar. From Science News:
To manipulate sound waves in air, (electric engineer Steven) Cummer’s team designed and built a cloak that sits atop an object like a piece of draped carpet. By layering simple metamaterial building blocks – ordinary strips of perforated plastic – the researchers hid a triangular wooden block a couple of inches high and more than a foot long at its base.
Sound waves over a range of high but audible frequencies slowed and changed direction cleanly after striking the holey plastic. Most reemerged appearing to have traveled all the way down to the flat surface beneath the block.
The prototype is two-dimensional – both the speaker generating the sound and the microphone recording it must be in the same plane above the object. But Cummer believes he could make a 3-D version that would cover an entire bump on a log, not just a slice.
“We are still a long way from a full acoustic cloak, but this carpet cloak is a step in the right direction,” says Andrew Norris, a physicist at Rutgers University in Piscataway, N.J.
The office I work in is full of things old people buy to make themselves feel young again. I can honestly say that our awesome new toy, The Swagtron T3 Hoverboard, makes me feel very, very old. I’ll explain why later. Swagtron T3 Pros There’s no way to overcharge the battery and that means no […]
One thing that’s consistent among amateur pool players is that they unknowingly stand up during their shots. Just as in golf, pool players need to keep their heads down and stay still after they shoot in order to hit straight. The DIGICUE helps keep shots consistent by letting you know every time you’ve had extra […]
A leaked memo from Apple CEO Tim Cook to his staff explaining why he met with Donald Trump — a guy who called Apple traitors for refusing to defeat their own security — explains the rationale: “tax reform.”
Traditional folding wallets are designed for paper bills—but these days, carrying cash is rarely a necessity. More often than not, I don’t carry cash at all. This Bogui Clik Wallet is the best answer I’ve found for avoiding the hassle of those tight-fitting credit card pockets.This attractive, minimalist wallet features a protective lip, so my cards don’t […]
Using my iPhone while it’s charging is always a hassle. With tucked-away outlets and the meager length of included lightning cables, comfortable scrolling while plugged in is annoying. These 10-Ft MFi-Certified Lightning Cables are super convenient and probably the best iPhone accessory purchase I’ve made.At over three times the length of normal cables, these reach anywhere you […]
With countless applications for modern life, artificial intelligence (AI) is one of the most in-demand fields of study in tech. Beyond modelling human decision making processes and learning abilities, AI can be used to analyze massive volumes of data and create complex interactive systems.This Machine Learning & AI for Business Bundle made mastering these concepts possible for […]