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    Daban town is famous for girls and windmills, while Loulan is a myth (神话) in the desert. Two thousand years ago, beside the beautiful Luobu Lake, there lay Loulan ancient city of the Silk Road. Businessmen from every country gathered there with lots of dancing parities. Everything shows that people in Loulan lived a rich life then.

    However, two thousand years later, this rich land suddenly disappeared from the map of China. It became an area covered with sand and dead tree trunks.

    Loulan was first "discovered" by a Swedish man named Sven Hedin in 1900, and people from America, Britain, Japan and Sweden all set foot here. Then in the 1930s, a Chinese named Huang Wenbi came to Loulan for the first time. He visited and studied this area and found many relics that were beautifully and carefully made.

    It is recorded that the ancient city of Loulan was the capital of the Loulan Kingdom during the Han and Jin Dynasties, and covered an area of some 10, 000 square kilometres. Inside the city, there are the ruins of government offices, temples and other old buildings. Outside the city there are some dried-up rivers and much farmland. In the past century many things have been dug up there including Han Dynasty coins, mirrors and many others of Greek and Roman times. All these things show that a lot of business between the East and the West once took place there.

    Lying on the northwest of the Lop Nur area, the Loulan Kingdom is now a lifeless area with endless ＂forests＂ of mounds (小丘) which aren't easily seen in other parts of the world. Its mystery has been attracting many people from many countries.

    Scientists are using robots to study the health of waters in and around Venice, Italy. The robots are designed to act like fish, other underwater creatures and plants. The scientists are working with several universities and research centers as part of a group called subCULTron. The European Union gives money to the project as part of its Horizon 2020 program whose aim is to take great ideas from the lab to the market and support science and innovation (创新) in Europe. The scientists want to use the artificial intelligence of the robots to help humans understand what is happening under the water of the Venice lagoon (潟湖).

    SubCULTron, a collective artificial intelligence project, plans to create the biggest shoal (鱼群) of robot fish in the world. The project's aim is to improve knowledge of the seabed and try to turn human abilities into hi-tech items.

    Alexandre Campo, a computer scientist, says the scientists have looked at the way animals learn to work in groups to understand how robots can learn to work together. The subCULTron project wants its robots to learn to work together so they can watch out for changes and new problems in the water.

    One problem the researchers had in the beginning was how the robots would communicate with each other. Wi-Fi and GPS equipment don't work underwater. Instead，the robots can use sonar (声呐) and an electric field.

    Another problem was charging batteries. The robots come up to the water's surface and stay near a boat or a power station to charge without any electrical cables. Besides, how to be water- proof, especially for some key pads of the robots, was really tough. Fortunately, a special mixture has been created to be pinned on the robot, which successfully stands the test of water.

    The health state of the lagoon is pretty good. There are no industrial polluters, and the city now has a modem sewer (污水管) system. It's not like before when all the waste flushed directly into the water. The robots in Venice will continue their work until 2019. The subCULTron project hopes they develop into “an artificial society underneath the water surface” that serves “a human society above the water”.

    Sometimes we start a day with the previous day still in mind. We think about the mistakes we made in the previous day, how things went wrong, and how we felt bad about it. No wonder it becomes difficult to focus on the current day.

    Here are some steps on how to start your new day fresh:

    ⒈Take time to evaluate your day

    At the end of a day, take some time to think about it. The purpose of this thinking time is not to regret how bad your day was, how things went wrong, or how people treated you badly. This won't do you any good. Instead, the purpose of this thinking time is to extract（吸取）lessons which you can bring to the following day.

    ⒉Make a commitment to apply the lessons

    After you extract the lessons, you should make a commitment to apply them. To do so, find some actionable things you can do to apply the lessons. Next, remind yourself to do them. You may write them down if you want to.

    ⒊“Close” your day

    After you have spent the time to think about the day and extract the lessons, make a decision to “close” the day. You are done with it; don't think about it anymore.

    ⒋Bring only the lessons to the next day and nothing else

    After you “dose” a day, you should not bring anything out of it to the next day except for the lessons you extract. Focus on applying the lessons to the present. This way you will be able to start your day fresh without the burden of yesterday.

    Science fiction writers create imaginary worlds. The way things work in your imaginary worlds will be based on actual science. So it's important for you to be familiar with the scientific principles and inventions that are related to your creation. For example, if you're writing about human living on a planet with zero gravity, then you need to know the effects of zero gravity on the human body.

    Then you have to figure out the exact rules of your imaginary worlds. And you have to follow them. If humans are able to breathe underwater in Chapter 1, your character can't drown in a swimming pool in Chapter 3. The issue here is maintaining your readers' trust. That means the readers are willing to pretend along with you. If you start out with an ordinary detective novel and then throw in someone breathing underwater in the 6th chapter, you will pull the readers out of their imagination. The same thing happens if you change the rules halfway.

    Part of your preparation work for the novel is to map out its worlds in great detail. You should decide the following issues: the history of the world, the geography, what possibilities it offers, how everything works in this new reality, and how all of these factors affect the way your characters think, feel, and react to things. You don't have to tell your readers all the rules in the first chapter. But you have to let readers know enough to understand what's going on. This also allows you to work out logical problems and contradictions before you start writing.

    When you are writing, remember to make it feel real. You are inviting readers to visit a new world. They will want to be able to see, hear, feel, smell, and even taste what it's like. Whether your novel is about a world without disease or an undiscovered planet, help your readers feel like they're actually there.

    On a recent spring morning. Susan Alexander, a retired government intelligence analyst, left her Maryland home, climbed into her Volkswagen Passat and drove about three miles to pick up two strangers. She battled rush-hour traffic on the Capital Beltway and George Washington Memorial Parkway before dropping them off at Reagan National Airport. She didn't earn a cent for her trouble, and that was the point.

    Alexander is a member of the Silver Spring Time Bank-one of more than 100 such exchanges around the world trying to build community by exchanging time credits for services instead of dollars and cents. "I have time," she said. "I like giving the gift of time to other people."

    In Alexander's case, passengers Mary and Al Liepold were grateful for the ride, but it wasn't charity. Mary, a retired writer and editor for nonprofit organizations, used time credits she banked for editing work and baking. Senior citizens who don't drive, the Liepolds cashed in their credits to catch a flight to Montreal for a five-day vacation.

    Without money changing hands or shifting between virtual accounts, the airport drop-off was more like a coffee party than a taxi ride. Driver and passengers chatted about projects they've completed for the time bank, and no one raised an eyebrow when Mary said she likes "to avoid the conventional economy."

    "The beauty of this is that you make friends," Mary Liepold said. "You don't just get services."

    The Silver Spring Time Bank formed in 2015 and has about 300 members, said co-founder Mary Murphy. Last year, she said, l,000 hours were exchanged for basic home repairs, dog walking, cooking and tailoring, among other services, without the exchange of money. "You get to save that money that you would have spent," she said. "You get to meet somebody else in your community and get to know that person. That's a bonus that's part of an exchange."

    A deal performed partly to make friends would seem to go against classical economics and one of Benjamin Franklin's most memorable sayings: "Time is money." To those at the forefront of modem time-banking, that is the appeal.

    Andrew Ritchie, inventor of the Brompton folding bicycle, once said that perfect portable bike would be "like a magic carpet... You could fold it up and put it into your pocket or handbag". Then he paused: "But you'll always be limited by the size of the wheels. And so far no one has invented a folding wheel."

It was a rare — indeed unique — occasion when I was able to put Ritchie right. A 19th-century inventor, William Henry James Grout, did in fact design a folding wheel. His bike, predictably named the Grout Portable, had a frame that was divided into two and a larger wheel that could be separated into four pieces. All the bits fitted into Grout's Wonderful Bag, a leather case.

    Grout's aim: to solve the problems of carrying a bike on a train. Now doesn't that sound familiar? Grout intended to find a way of making a bike small enough for train travel: his bike was a huge beast. And importantly, the design of early bicycles gave him an advantage: in Grout's day, tyres were solid, which made the business of dividing a wheel into four separate parts relatively simple. You couldn't do the same with a wheel fitted with a one-piece inflated(充气的) tyre.

    So, in a 21st-century environment, is the idea of the folding wheel dead? It is not. A British design engineer, Duncan Fitzsimons , has developed a wheel that can be folded into something like a slender ellipse(椭圆). From beginning to end, the tyre remains inflated.

    Will the young Fitzsimons's folding wheel make it into production? I have no idea. But his inventiveness shows two things. First, people have been saying for more than a century that bike design has reached its limit, except for gradual advances. It's as silly a concept now as it was 100 years ago: there's plenty still to go for. Second, it is in the field of folding bikes that we are seeing the most interesting inventions. You can buy a folding bike for less than £1,000 that can be knocked down so small that can be carried on a plane ——minus wheels, of course ——as hand baggage.

    Folding wheels would make all manner of things possible. Have we yet got the magic carpet of Andrew Ritchie's imagination? No. But it's progress.