A team of engineers at Harvard University has been inspired by Nature to create the first robotic fly. The mechanical fly has become a platform for a series of new high-tech integrated systems. Designed to do what a fly does naturally, the tiny machine is the size of a fat housefly. Its mini wings allow it to stay in the air and perform controlled flight tasks.

    “It's extremely important for us to think about this as a whole system and not just the sum of a bunch of individual components (元件),” said Robert Wood, the Harvard engineering professor who has been working on the robotic fly project for over a decade. A few years ago, his team got the go-ahead to start piecing together the components. “The added difficulty with a project like this is that actually none of those components are off the shelf and so we have to develop them all on our own,” he said.

    They engineered a series of systems to start and drive the robotic fly. “The seemingly simple system which just moves the wings has a number of interdependencies on the individual components, each of which individually has to perform well, but then has to be matched well to everything it's connected to,” said Wood. The flight device was built into a set of power, computation, sensing and control systems. Wood says the success of the project proves that the flying robot with these tiny components can be built and manufactured.

    While this first robotic flyer is linked to a small, off-board power source, the goal is eventually to equip it with a built-in power source, so that it might someday perform data-gathering work at rescue sites, in farmers' fields or on the battlefield. “Basically it should be able to take off, land and fly around,” he said.

    Wood says the design offers a new way to study flight mechanics and control at insect-scale. Yet, the power, sensing and computation technologies on board could have much broader applications. “You can start thinking about using them to answer open scientific questions, you know, to study biology in ways that would be difficult with the animals, but using these robots instead,” he said. “So there are a lot of technologies and open interesting scientific questions that are really what drives us on a day to day basis.”

B

    Researchers say they have created a new super-tough material in the laboratory. It is stronger, lighter and costs less than steel. But the new material is not a product of high technology. It is wood. Researcher Liangbing Hu says that it can compete with some of the world's strongest materials or even replace steel.

    The product is called Super Wood. It doesn't require any special raw, unprocessed material. That means the cost of the product will be relatively low.Hu said, “We can start with very cheap wood, and also very fancy, expensive wood. But in the end, we get very similar performance.”

    Super Wood is made by partially removing a natural polymer called lignin（木质素）. Hu explained, “Lignin is like glue to hold all the parts together in natural wood. To be able to densify（增密）the wood completely, some of the lignin has to be removed. “Strong chemicals are put on the wood to remove about half of its lignin. Then, after being left in extreme heat and pressurized for a day, the treated wood is ready.

    The wood is strong enough to build automobiles, airplanes, wind turbines and more. Researchers are finding many new ways to use wood, including creating batteries and see-through wood and paper.Hu said, “Wood has been existing on Earth for more than a million years. And human beings have been using wood for furniture, construction for more than 10 thousand years. And the more we worked on this material, we realized, we have never fully exhausted the potential of this amazing material.”

    Animals, including insects, do not have a language like ours. They do not talk to each other in words and sentences. But if we watch them, we can see that they do have ways of communicating with each other.

    Can you see the rabbits' tail? When rabbits see this white tail moving up and down, they run too. The rabbit has reminded them of potential dangers without making a sound. It has given them a signal.

    Many other animals use this kind of language. When a cobra (眼镜蛇) is angry, it raises its hood (兜帽) and makes itself look fierce. This warns other animals. When a bee has found some food, it goes back to its home. It cannot tell the other bees where the food is by speaking to them, but it does a little dance in the air. This tells the bees where the food is.

    Some animals say things by making sound. A dog barks, for example, when a stranger comes near. A cat purrs (猫的呜呜声) when pleased. Some birds make several different sounds, each with its own meaning. Sometimes we human beings speak in the same way. We make sounds like “Oh” or “Ah!” when we are frightened or pleased or when we drop something on our toes.

    But we have something that no animals have — a large number of words which have the meanings of things, actions, feeling or ideas. We are able to give each other all kinds of different information in words and sentences, which no other animals can do. No other animals have so wonderful a language as we have.

    As scientists in the Netherlands tried to figure out how to build a super flying robot, they learned from one of nature s flyers: the humble fruit fly(果蝇).And by building this robot, they've gained new insights into how the fly carries out one of its dangerous tasks.

    The robot is called the DelFly Nimble Its wingspan(冀展)is about a foot wide. It has four wings that can beat at 17 times per second, which appear very delicate because they're made of the same material as space blankets.

    In the previous designs, they always had a tail, like a traditional airplane tail, said the robots main designer Matej Karasek. He's based at the Micro Air Vehicle Laboratory at Delft University of Technology in the Netherlands, and he and his colleagues published their findings on Thursday in Science

    “In the previous generations", he said, "flapping wings drove the robot forward while the tail helped to guide and stabilize it. But now the DelFly Nimble is completely controlled by the wings. The challenge then was actually combine the control into the wing movement, and that's what we achieved, Karasek said

    In the latest generation. the wings can each move individually or rotate(旋转)around the body of the robot in order to maximize the machine s agility(灵活 ) The robot can remain in one place in the air for about five minutes on a full battery or fly for more than a kilometer"， Karasek said, "And because the scientists are controlling all the movements, they can use the robot to learn more about how fruit flies actually carry out their dangerous tasks, which has caught the attention of biologists.”

    Do you always agree to do things that you are unwilling to do? Are you the type of person who always says "yes"? I've come to learn that it is very important to learn to say NO! It's okay. People are still going to like you. They may even respect you more because they know you are honest.

    I'm not saying to say "no" to someone who really needs your help. I'm talking about refusing that meeting that you really do not want to attend or that birthday party that you don't want to be a guest at.

    Think for a moment how you feel when you say YES to something that you really don't want to do. If you're like I once was, you can't sleep at night and you think about it too much. It weighs on your mind. You try to find ways out. Whatever you're saying to yourself, if you really wanted to go, you wouldn't have all of these thoughts.

    So, why not just say NO from the beginning? Maybe you feel like if you don't show up at the meeting (by the way, it is not the one you must attend) your boss isn't going to like you or your co-workers won't respect you. Maybe you feel as if your mom, dad or sisters won't love you as much if you don't do everything for them that they ask every occasion.

    If these people are your true friends, family members, or a good boss, they will like or love you the same no matter what. People treat you the way you teach them to, and if you're someone who always says "yes", then that's what they're expecting.

    You need to do what is right for you. Of course we do have real obligations in life to fulfill, but we do not have to do everything others want us to do.

    A good relationship between students and teachers makes the classroom a very inviting place. When you like your teachers, it's easier to pay attention to their explanations and improve your marks. When you consider your teachers as friends, you'll certainly have more respect for them. When your teachers consider you to be a friend, they'll feel more open in class and that will probably influence the classroom in a positive way. Now here are some tips to develop a friendly relationship with your teachers:

    Ask questions. If you have any questions about that subject, ask them. Show them that you're interested in their subjects. That will make them notice you. But never ask questions that you already know the answers to. If your teachers realize that you are not asking real questions, they might think that you're not actually trying to learn, but only trying to make an impression.

    Talk about non-school subjects. When you see one of your teachers in the hall, greet him/her and ask if he/she is going to that concert or if he/she has seen that movie. That way you'll show that you consider him/her as a reined. Some teachers don't like to have friendly relationships with students, but most of them are happy to chat with their students. After a while, they may start to talk with you about non-school subjects in the classroom.

    The rest is totally up to you; it is very easy to develop a friendly relationship with any of your teachers. If you want to be friends with your teachers, just treat them as friends, but don't forget that no matter how good friends you are, they will still be your teachers and deserve your respect.