Science Briefs: Lowering hum in aircraft cabins
NCSU: Membrane on aircraft could lower cabin hum
An in-flight annoyance shared by many: that low-frequency noise that penetrates the cabin. Now researchers from N.C. State and the Massachusetts Institute of Technology have developed a vibration-blocking membrane that can be incorporated into aircraft structure to drastically reduce that hum.
Aircraft designers incorporate lightweight materials with a honeycomblike structure into wings, floors and cabins, for strength and fuel efficiency – but they’re bad at blocking low-frequency noise.
The researchers created a thin, lightweight membrane to cover one side of the honeycomb structure, like the skin of a drum. When sound waves hit the membrane, they bounce off the membrane instead of passing through it. The membrane, made of rubber, is about .025 millimeters thick.
“It’s particularly effective against low-frequency noise,” said Yun Jing, an assistant professor of mechanical and aerospace engineering at N.C. State and senior author of a paper describing the work, published in Applied Physics Letters. ncsu.edu
UNCC engineers win Army-sponsored 3-D competition
UNC Charlotte Lee College of Engineering students formed the bulk of a team that recently won a 3-D printing design competition sponsored by the U.S. Army Research Office. James Haig and Nathan Lambert (master’s students in mechanical engineering), Patrick Fain (bachelor’s student in mechanical engineering technology) and Eric Fleischhauer (doctoral student in mechanical engineering) won the competition to develop ideas and concepts for items that would be useful in a military environment where 3-D printing would offer an advantage. They created a 3-D-printed impact-protection capsule that could prevent damage to 35 pounds of ammunition parachuted by a helicopter traveling about 103 mph from an altitude of 150 feet.
Five teams of students across North Carolina, each with a military adviser, competed. Staff reports
Engineering skills help fire ants invade
Scientists from the Georgia Institute of Technology investigated how fire ants excavate their impressive nests. Using complex 3-D CT-scanning, they discovered the pests are successful invaders because they are able to construct nests regardless of grain size.
They also noticed that on average the ants built tunnels faster in coarser soils. Also, that as hydration increased the ants went deeper in the finer soils, though they built more complex branched structures in moister coarse soils. Above 5 percent saturation, the wetness of the soil had little effect on the ants’ ability to construct nests – but in dry soils, the ants could barely dig at all.
The findings appear in the Journal of Experimental Biology. biologists.com
Brain to blame for late-night snacking?
Researchers at Brigham Young University in Utah may have found why you raid the fridge late at night: Some areas of the brain don’t get the same “food high” in the evening.
The scientists used MRI to measure how people's brains respond to high- and low-calorie food images at different times of the day. The results showed that images of food, especially high-calorie food, can generate spikes in brain activity, but those neural responses are lower in the evening.
“You might over-consume at night because food is not as rewarding, at least visually at that time of day,” said lead author Travis Masterson. “It may not be as satisfying to eat at night so you eat more to try to get satisfied.”
Subjects looked at images of both low-calorie foods (vegetables, fruits, fish, grains) and high-calorie foods (candy, baked goods, ice cream, fast food). As expected, the researchers found greater neural responses to images of high-calorie foods. byu.edu
This story was originally published May 9, 2015 at 10:55 PM with the headline "Science Briefs: Lowering hum in aircraft cabins."