Zhonglin Wang started playing table tennis only four years ago. But last year, he and other researchers came up with a clever way to improve their game: Build a smart table.

Now they’ve just introduced a prototype to the public. It can measure where a ball lands, how fast the ball’s going and where it’s headed. The table can do that because its innovative wood surface forms the top layer of a novel self-powered sensor. The data it acquires could help players to perform better, says Wang.

Wang is a materials scientist at the Georgia Institute of Technology, in Atlanta. He describes the invention as a machine that can learn to analyze how someone plays. Importantly, the new smart table doesn’t need a battery to detect the ball. When a ball hits the wood, it sets off a chain of events that can both generate a small electric current and record the ball’s behavior.

Wang is an expert at inventing devices that provide their own power. In 2012, he invented a triboelectric(摩擦生电的) nano-generator. He calls it TENG, for short. Even if you’ve never heard of “triboelectricity”, you know the phenomenon. Most of us call it static electricity. The first TENG that Wang put together in 2012 looked like a sandwich. It had layers of charged materials separated by a small gap. When the sandwich bent or changed shape, its layered materials rubbed against each other. This caused electrons to start building up on one side.

What makes the new game table truly unique is its use of wood as one of the TENG’s layers. As it turns out, Wang explains, “Wood is an excellent triboelectric material.” Building a full-size game table would require a large grid of wood TENGs. Wang says that’s on his drawing board as a project for the future.

I’m a strong believer that learning different languages makes you look incredibly good when you’re in a foreign country and can understand and speak the language. The list below is 4 apps that will help you learn a foreign language! You can download them for free.

Babbel：Learn Languages

Babbel is an excellent language tool to help you progress step by step with learning a new language. It helps you learn grammar along the way as you work your way through the tasks and assignments. You need to pay a monthly subscription(订阅费)，but this will still be cheaper than taking physical lessons with a tutor!

Duolingo：Learn Languages for Free

The app has many languages to choose from and will work through the basics all the way to advanced words and sentences. It’s all completely free too! It’s incredibly well designed，looks great and will help you learn，remember and progress with just a little bit of time every day.

Tandem：Language Exchange

Rather than have you work through tasks and memorize different things，the app lets you match with people who share your interests but speak the language you want to learn. You can then have text，voice and video conversations with people who want to learn your native language，and in return you learn theirs，all by simply communicating with each other. It’s a great way to learn with only $1 a day.

Busuu：Learn English

This app is perfect if you want to learn English. There are all sorts of audio and visual learning aids. You’ll find yourself working through interactive tests and learning tools for vocabulary and dialogue.

Not so long ago,most people didn't know who Shelly Ann Francis Pryce was going to become.She was just an average high school athlete.There was every indication that she was just another American teenager without much of a future.However,one person wants to change this.Stephen Francis observed then eighteen-year-old Shelly Ann as a track meet and was convinced that he had seen the beginning of true greatness.Her time were not exactly impressive, but even so,he seemed there was something trying to get out,something the other coaches had overlooked when they had assessed her and found her lacking.He decided to offer Shelly Ann a place in his very strict training seasons. Their cooperation quickly produced results,and a few year later at Jamaica's Olympic games in early 2008,Shelly Ann,who at that time only ranked number 70 in the world,beat Jamaica's unchallenged queen of the sprint（短跑）.

"Where did she come from?"asked an astonished sprinting world,before concluding that she must be one of those one-hit wonders that spring up from time to time,only to disappear again without signs.But Shelly Ann was to prove that she was anything but a one-hit wonder.At the Beijing Olympic she swept away any doubts about her ability to perform consistently by becoming the first Jamaican woman ever to win the 100 meters Olympic gold.She did it again one year on at the World Championship in Briton,becoming world champion with a time of' 10.73—the fourth record ever.

Shelly-Ann is a little woman with a big smile.She has a mental toughness that did not come about by chance. Her journey to becoming the fastest woman on earth has been anything but smooth and effortless,She grew up in one of Jamaica's toughest inner-city communities known as Waterhouse,where she lived in a one-room apartment, sleeping four in a bed with her mother and two brothers.Waterhouse,one of the poorest communities in Jamaica,is a really violent and overpopulated place.Several of Shelly-Ann's friends and family were caught up in the killings;one of her cousins was shot dead only a few streets away from where she lived.Sometimes her family didn't have enough to eat.She ran at the school championships barefooted because she couldn't afford shoes.Her mother Maxime,one of a family of fourteen,had been an athlete herself as a young girl but,like so many other girls in Waterhouse,had to stop after she had her first baby.Maxime's early entry into the adult world with its responsibilities gave her the determination to ensure that her kids would not end up in Waterhouse's roundabout of poverty.One of the first things Maxime used to do with Shelly-Ann was taking her to the track,and she was ready to sacrifice everything.

It didn't take long for Shelly-Ann to realize that sports could be her way out of Waterhouse.On a summer evening in Beijing in 2008,all those long,hard hours of work and commitment finally bore fruit.The barefoot kid who just a few years previously had been living in poverty,surrounded by criminals and violence,had written a new chapter in the history of sports.

But Shelly-Ann's victory was far greater than that.The night,she won Olympic gold in Beijing,the routine murders in Waterhouse and the drug wars in the neighbouring streets stopped.The dark cloud above one of the world's toughest criminal neighbourhoods simply disappeared for a few days.“I have so much fire burning for my country,”Shelly said.She plans to start a foundation for homeless children and wants to build a community centre in Waterhouse.She hopes to inspire the Jamaicans to lay down their weapons.She intends to fight to make it a woman's as well as a man's world.

As Muhammad Ali puts it,"Champions aren't made in gyms.Champions are made from something they have deep inside them.A desire,a dream,a vision."One of the things Shelly-Ann can be proud of is her understanding of this truth.