Researchers designed an underwater acoustic ground cloak by engineering material with properties not typically found in nature, rendering an object invisible
Cloaking devices play a pivotal role in many sci-fi television programs. Scientists are now working to take this technology from the dramatic realm of science fiction and make it real. Amanda D. Hanford, at Pennsylvania State University, is taking the introductory steps to make acoustic ground cloaks. These materials redirect approaching waves around an object without scattering the wave energy, concealing the object from the sound waves.
During the 175th Meeting of the Acoustical Society of America, being held May 7-11, 2018, in Minneapolis, Minnesota, Hanford will describe the physics behind an underwater acoustic shield designed in her lab.
Hanford and her team set out to engineer a metamaterial that can allow the sound waves to bend around the object as if it were not there. Metamaterials commonly exhibit extraordinary properties not found in nature, like negative density. To work, the unit cell — the smallest component of the metamaterial — must be smaller than the acoustic wavelength in the study.
“These materials sound like a totally abstract concept, but the math is showing us that these properties are possible,” Hanford said. “So, we are working to open the floodgates to see what we can create with these materials.”
To date, most acoustic metamaterials have been designed to deflect sound waves in air. Hanford decided to take this work one step further and accept the scientific challenge of trying the same feat underwater. Acoustic cloaking underwater is more complicated because water is denser and less compressible than air. These factors limit engineering options.
After multiple attempts, the team designed a 3-foot-tall pyramid out of perforated steel plates. They then placed the structure on the floor of a large underwater research tank. Inside the tank, a source hydrophone produced acoustic waves between 7,000 Hz and 12,000 Hz, and several receiver hydrophones around the tank monitored reflected acoustic waves.
The wave reflected from the metamaterial matched the phase of the reflected wave from the surface. Additionally, the amplitude of the reflected wave from the cloaked object decreased slightly. These results demonstrate that this material could make an object appear invisible to underwater instruments like sonar.
Using linear coordinate transformation, the researchers were able to map the flat surface of the bottom of the tank and determined that space was compressed into two triangular cloaking regions consisting of the engineered metamaterial.
These results show potential to contribute to real-world applications, such as acoustic materials to dampen sound and appear invisible underwater.
The Latest on: Cloaking device
via Google News
The Latest on: Cloaking device
- Star Trek technology of the future is hereon January 18, 2020 at 10:55 pm
Star Trek Capt. James T. Kirk had amazing technology at his fingertips. Cloaking devices and holodecks were cool, but they didn’t seem nearly as cool and accessible for my little 9-year-old brain as ...
- World War II Almost Saw The Allies Employ 'Cloaking Devices' On Navy Shipson December 31, 2019 at 1:02 am
Cloaking devices are a staple of science fiction. But while a Klingon Bird-of-Prey materializing out of thin air makes for fun special effects, real-world stealth technology has mostly focused on ...
- Researchers Create “Romulan Cloaking Device”on September 26, 2019 at 5:36 am
On Star Trek, Captains Kirk and Picard often had to contend with their Romulan adversaries who possessed a “cloaking device” that rendered their ships invisible. On Star Trek, Captains Kirk and Picard ...
- Gears 5 Horde Mode Trailer Reveals New Featureson August 18, 2019 at 5:00 pm
The Horde mode in Gears 5 will add ultimate abilities, like a cloaking device. It will also add the ability for players to play as robot companion JACK to zip around the field field and help with ...
- Acoustic Cloaking Device Lets Sound Travel Uninterrupted Around Objectson August 16, 2019 at 5:00 pm
A new type of acoustic cloak would allow sound waves to travel around an object unimpeded, and could be used to build better concert halls, quiet spaces and noise-shielding head gear, researchers ...
- No Cloaking Device Here: F-22 Stealth Fighters Can Be Trackedon May 20, 2019 at 4:56 pm
“Does the mission require a cloaking device or is it OK if the threat sees it but can’t do anything about it?” State-run Chinese media is claiming that the People’s Liberation Army has ...
- Direct current remote cloak for arbitrary objectson March 12, 2019 at 5:00 pm
In this paper, we propose the first experimental realization of a remote cloaking device that makes any object located at a certain distance invisible at direct current (DC) frequency. A negative ...
- 'Cloaking device' used during break-in at shopon February 20, 2019 at 7:20 am
Burglars used a 'cloaking device' to fill a shop with artificial smoke during a break-in in the early hours of this morning. Police and firefighters were called to the McColls shop on Congleton ...
- New cloaking technique lets light pass right on throughon July 1, 2018 at 5:00 pm
Now, researchers have developed a new device that works in a completely different way to existing cloaking technology, neatly sidestepping some past issues and potentially helping to hide everyday ...
via Bing News