If someone created a flying machine capable of tracking you down by listening for your voice, you might be terrified. But what if you were trapped in ruins after a natural disaster and first responders couldn't locate you? Maybe then a human-seeking drone(无人机)wouldn't be such a terrible idea. That concept is the focus for engineers at Germanys Fraunhofer FKIE Institute, who've built a drone to find people by detecting(探测)human screams.

"The human-seeking drone would be ideal for post-disaster situations, such as earthquakes, hurricanes and wildfires," said Macarena Varela, one of the lead engineers "They could hover over an area that rescue crews have difficulty getting to and locate exactly where people may be trapped."

Locating people by sound presents its share of challenges. An auditory(听觉的) system would need to distinguish human cries from sounds that often happen in nature such as animal calls and wind. It might also need to recognize patterns associated with kicking, clapping or other ways people try to get the attention of rescue teams.

Engineers took those situations into account when building out their concept drone. They recorded themselves screaming, tapping and creating other noises that might be a sign of people in trouble. Then, they analyzed each sound frequency to find common signatures and used those to train artificial intelligence software. They also worked to remove the noise created by the drone and other environmental sounds.

Once the software part was complete, the team placed tiny digital microphones under the drone and used signal processing techniques that enabled them to track where human noises are coming from. The microphones also enhanced the volume and clarity of the speech. So far, they have conducted successful open field experiments, finding that the drone can estimate a victim's location within a few seconds of picking up sound.

Next, they would like to add a higher frequency microphone to a drone to acquire more audio sound signals. The idea is to pick up noises from hundreds of meters away. Varela said. In the real world, victim's location data might one day be sent wirelessly to emergency crews carrying a tablet.

Researchers have proposed a novel method for counting and tracking vehicles on public roads, a development that could improve current traffic systems and help travelers get to their destinations faster. 

Using the cameras already installed on campus buses at the Ohio State University, researchers proved that they could automatically and accurately measure counts of vehicles on urban roadways, detect objects in the road and distinguish parked vehicles from those that are moving. 

In previous studies, Ohio State researchers found that using these mobile cameras provides much better spatial and temporal (时间的) coverage than relying on often temporarily placed sensors that don't provide a view of many streets and roads in a city.

"If we collect and process more high-resolution (高清) spatial information about what's happening on the roads, then planners could better understand changes in demand, effectively improving efficiency in the broader transportation system," said Keith Redmill, lead author of the study.

"If we can measure traffic in a way that is as good or better than what is conventionally done with fixed sensors, then we will have created something incredibly useful extremely cheaply," he said. "Our goal is to start building a system that could do this without much manual intervention because if you want to collect this information over lots of potential vehicles and lots of time, it's worth fully automating that process."

While still a long way from total implementation (实施), the study suggests the system's results bear promise for the future of intelligent traffic surveillance. Transportation planners, engineers and operators make vital decisions about the future of our roadways, so when designing transportation systems to work over the next 30 to 50 years, it's necessary that we give them data that allows them to improve the efficiency of the system and the level of service provided to travelers.

World Book Day author A.M. Dassu shares some tips

While helping out at her children's swimming lessons, author A.M. Dassu noticed that one boy always put on his socks too soon afterwards. He inspired her to write a picture book that she called Soggy Socks.

Today, many years later, Dassu has published lots of children's books. Every day, after taking her children to school, Dassu goes to her desk to write. "I leave my phone upstairs so I don't get distracted, and try to write 800 words every day," she says. Dassu believes that the key to being a successful writer is not necessarily talent but "getting your bottom on the seat".

The cyclist with far to go

After 527 days, Liam Garner has completed an amazing achievement. He has cycled almost 20,000 miles from Alaska, in the very north of the US, to Ushuaia-the world's southernmost city-in the South American country of Argentina. Garner, who was 17 years old when he set off, said his trip was inspired by a book he read about a similar journey.

Garner always wanted to have a "big adventure". During his trip, Garner travelled through 14 countries. He camped outside, stayed in hostels or was hosted by local families. He faced some challenges, including an accident that meant he had to take some time off. However, he recovered and finally reached his goal of being the youngest person ever to cycle from Alaska to Argentina.

A plastic-waste warrior

Licypriya Kangujam won an international award which celebrates people who spark global change. Licypriya, who is 11 and from India, won it for her Plastic Money Shop, where people can trade in their single-use plastic waste for useful items such as stationery, rice or young trees to plant.