Applied Physics
Researchers say they have discovered an entirely new mechanism for making common electronic materials emit laser beams. The finding could lead to lasers that operate more efficiently and at higher temperatures than existing devices, and find applications in environmental monitoring and medical diagnostics.
The light emitted by a laser differs fundamentally from light produced by common sources such as the sun, fire, or electric lamps. According to the field of physics called quantum electrodynamics, light is made up of particles called photons. Common sources of light emit photons that…
On its opening day, the London Millennium Bridge experienced unexpected swaying due to the large number of people crossing it. A new study finally explains the Millennium Bridge 'wobble' by concluding that humans did not walk the way engineers would have preferred.
It has generally been thought the Millennium Bridge 'wobble' was due to pedestrians synchronizing their footsteps with the bridge motion. However, this is not supported by measurements of the phenomenon on other bridges.
Instead, it was the behavior of pedestrians and it has also been identified on several other bridges, including…
During launch into orbit, a satellite is exposed to a number of extreme stresses. At takeoff the extremely strong engine vibrations are transmitted via the launcher structure to the satellite, which is also exposed to a high-intensity sound levels (140 dB and more). The increasing speed of the of the rocket also leads to aerodynamic strains that turn into a shockwave when the launch vehicle's velocity jumps from subsonic to supersonic.
That's not all. When the burned out rocket stages are blasted off and the next stage is fired up, the satellite is exposed to temporary impulsive…
After it's conception and development during World War I, sonar is finally finding use in an unlikely medium: space. Astronauts on the International Space Station will soon be able to conduct experiments in zero gravity with no container contamination using beams of sound to control a sample.
Space-DRUMS, or the Space Dynamically Responding Ultrasonic Matrix System, uses a dodecahedron container armed with twenty ultrasonic beams that use sound to control the volume occupied by a sample inside.
The SpaceDRUMS 12-sided reactor is able to keep a baseball-sized sample from touching its walls.…
A key challenge of nanotechnology research is investigating how different materials behave at lengths of merely one-billionth of a meter. When shrunk to such tiny sizes, many everyday materials exhibit interesting and potentially beneficial new properties.
Magnetic behavior is one such phenomenon that can change significantly depending on the size of the material. However, the sheer challenge of observing the magnetic properties of nanoscale material has impeded further study of the topic.
Researchers at Rensselaer Polytechnic Institute have developed and demonstrated a new method for…
Research carried out at MIT's Alcator C-Mod fusion reactor may have brought the promise of fusion as a future power source a bit closer to reality, though scientists caution that a practical fusion powerplant is still decades away.
Fusion, the reaction that produces the sun's energy, is thought to have enormous potential for future power generation because fusion plant operation produces no emissions, fuel sources are potentially abundant, and it produces relatively little (and short-lived) radioactive waste. But it still faces great hurdles.
"There's been a lot of progress," says physicist…
Wouldn't it be great if your cell phone or mp3 player could charge itself? What if your house could generate electricity from the noise of the cars on the road? Or if the waste heat generated by your air conditioner could help put a dent in that expensive summer electric bill? As the demand for cheaper and more renewable energy sources increases, piezoelectrics - a class of material that produces an electric potential when mechanically deformed - may hold the key to unlocking the energy flowing all around us.
Piezoelectrics themselves are not new. In the early 1800's, Pierre and Jacques Curie…
Each year, coal-burning power plants, steel factories and similar facilities in the United States produce more than 125 million tons of waste, much of it fly ash and bottom ash left over from combustion. Mulalo Doyoyo has plans for that material.
An assistant professor in Georgia Tech’s School of Civil and Environmental Engineering, Doyoyo has developed a new structural material based on these leftovers from coal burning. Known as Cenocell™, the material offers attributes that include high strength and light weight – without the use of cement, an essential ingredient of conventional concrete…
A smart scientist is a frugal scientist. The Frugal Scientist is a series of articles focusing on frugality with special attention to the fundamentals of science.
When it comes to saving money on heating and cooling costs in the household, the frugal scientist must remember these tenets of Thermodynamics: 1) Heat/Thermal Conduction and 2) Closed Systems vs Open Systems.
Heat conduction or Thermal conduction
Heat conduction is the spontaneous transfer of thermal energy from a region of higher temperature to a region of lower temperature, which acts to equalize temperature differences.
Closed…