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When spring is gone the closure silenced Penn State schools and the nearby town of State College, the prosecution’s weapon was “listening.” A team of researchers from the university connected a hidden telecom fiber cable, which travels two and a half miles across the compass, turning it into a kind of scientific lighting equipment.
By scanning the laser through fiber optics, scientists can detect vibrations from the surface as a result of the slightest twist. When a car overturns a small cable or a passerby, the ground can spread their unique signature. Therefore, without looking up, scientists can draw a picture of how the area once lived, and gradually came to life again when the closure was reduced.
For example, they may be aware that the number of campers is about to end in April following the closure, and remain until June. But as the slowdown slowed, traffic began to rise. “You can see that the number of people traveling is still small compared to normal days, but the number of vehicles has returned to normal,” said Penn State energy expert Tieyuan Zhu, a new journalist. paper describe the work in the newspaper Ancient Writings. The fiber optic cable is able to distinguish such a smart signal. ”
Basically, then frequencies in the sign. The human foot emits between 1 and 5 hertz waves, while traffic travels at about 40 or 50 hertz. Rumbing from the construction machine jumps above 100 hertz.
Fiber optic cables work by properly opening the light intensity and taking them over long distances as signals. But when a car or a person passes by, the vibration causes confusion, or imperfection: less light disperses back to the source. Because light speeds are known, Penn State researchers are able to light a laser through a single fiber optic cable and measure different wave vibrations by calculating the time at which the diffused light travels. This technique is known in geoscience as the distribution of vocal cords, or DAS.
The traditional seismograph, which states that tremors are internal movements, simply measuring events in one place on Earth. But by using this method, scientists can measure more than 2,000 miles over a mile — one-and-a-half miles — and give them a better view of the surface. He did so in mid-March 2020, when the closure began, and in June 2020, when businesses at State College had begun to reopen.
Starting with the signature, DAS can indicate that west of the campus, where there was a new parking lot, there was no industrial activity in April when construction stopped. In June, researchers not only saw the shock of the recurring machines, but they were able to select construction vehicles, which move at a slower pace. However, he added, meanwhile, the situation of school walkers was not yet clear, although some prevention measures had been reduced.
DAS can be a powerful tool for tracking human movement: Instead of exploring the state of mobile phones, researchers can use fiber optics to track commuters and vehicles. But technology cannot awareness car or person. “You can tell if it’s a car, if it’s a truck, or a bicycle. But you can’t say, ‘Oh, this is a Nissan Sentra, 2019,’ ”says Stanford University student Ariel Lellouch, who uses DAS but has not participated in the study but has reviewed it. “The anonymity of DAS is one of the biggest advantages, in particular.”
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