Bridges are a common sight in the Netherlands. But four bridges are particularly unusual: each 26-foot structure was fashioned from concrete by a giant robotic printer. They are part of a revolution (变革) that is seeing 3D printers move from the tabletop to the construction lot.
3D construction printers work a lot like home-office ones, except instead of ink they spit out concrete. Nozzles (喷嘴) run back and forth on rails, with computers controlling the time and speed, so that a layer of concrete is laid down where needed. By the time the slow-moving nozzle reaches the end of its path, the layer has usually hardened just enough to lay down another on top of the first, building up, layer-by-layer, a home-sized wall. With precise pattern of deposit, the nozzle can leave spaces for windows, doors, and other design and structural elements.
It takes about 24 hours of printing to build a 500-square-foot single-floor home. “The printing process delivers structure, wall-sheeting, inner and outer surface finishing, all at the same time,” says Jason Ballard, co-founder and CEO of ICON, an Austin, Texas company. “That normally takes 20 people representing five or six different trades working several days.”
3D construction printers are also less wasteful. A typical home construction site generates about four tons of waste. Because the concrete used in conventional construction is applied uniformly, regardless of whether it’s needed for structural support in a particular area or not, about half of the concrete is wasted. 3D printers, however, can vary the thickness of a structure with great precision, using concrete only where it is really needed.
So far, printed buildings have been modest, low-cost affairs. For instance, ICON printed a house in Austin, Texas, intended for families, at a cost of $10,000, and has a contract to print a total of six. Then it plans to take a printer down to Latin America to build 50 low-cost homes there.
1. Why does the author discuss the nozzle in Paragraph 2?| A．To analyze why the nozzle is so important. | B．To confirm 3D construction printers are slow. |
| C．To explain how 3D construction printers work. | D．To argue the precision of the nozzle needs improving. |
| A．They are highly efficient. | B．They are a little complex. |
| C．They increase the building cost. | D．They will replace builders one day. |
| A．By making a contrast. | B．By giving examples. | C．By describing a process. | D．By analyzing causes. |
| A．Printed Bridges Become a Fashion in the Netherlands | B．3D Printing Technology is Key to Housing Problems |
| C．Your House is Going to Be Greener in the Future | D．Your Next House May Come Out of a 3D Printer |
相似题推荐
【推荐1】Machine parts can easily wear or crack. If engineers had their way, machines would have no moving parts at all. Perhaps just one moving component would be an acceptable solution.
Such machines are now beginning to appear. Alloys of gallium that melt below room temperature are chosen. They have three properties: the highest surface tensions of any known liquid, good electrical conductivity, and extreme chemical reactivity, in the form of a willingness to donate electrons — a process known as oxidation — to nearby substances.
Kourosh at the University of New South Wales used these properties to design a machine with a single moving part: a continuous-flow reactor. This device is a circular 14 cm-long track, for reactants to flow around. It was interrupted by a single cavity containing a droplet of liquid metal connected to an electrical power source. An electrical current applied to the droplet produces a change in its surface tension. That, in turn, leads to a pressure difference strong enough to pull reactants across, allowing electron donation to happen and the desired chemical reaction to occur. The deformation of the droplet as it tenses and relaxes within its cavity pumps the resultant chemical away, allowing fresh reactants to flow in and the process to begin again.
The forces produced by surface tension dominate at small scales. At larger scales they aren’t superior to those generated by electromagnetism, on which conventional motors rely. This means that liquid metal engineering will be most useful for objects that are roughly centimetre-size and below. As this is where maintenance and repairs are the most demanding and costly, such a feature is good news.
And even though they will likely be limited to smaller devices, the appeal of liquid metals is easy to see. They experience none of the wear-and-tear that eventually causes machine parts to break down. Any damage they suffer is naturally self-healing. Gallium alloys, moreover, are easy to make, harmless to the touch. Just the ticket, in other words, for creative engineers.
1. Which is one of the characteristics of gallium alloys?| A．Their surface tensions are low. | B．They are always ready to attract electrons. |
| C．Electric currents pass through them easily. | D．They change to liquids only below room temperature. |
| A．It is pulled away. | B．It produces new chemicals. |
| C．Its shape changes. | D．It flows around the track. |
| A．Motors. | B．Forces. | C．Machines. | D．Objects. |
| A．Their limitations. | B．Their applications. |
| C．Their advantages. | D．Their functions. |
【推荐2】A new “smart bin” could mean the end of environment-conscious families spending hours sorting tins, cartons, bottles, and cardboard for recycling.
The invention, which can help sort rubbish into recycling categories without needing people to operate. It is being experimented in Poland and is set to go on sale in UK within a few years.
The bin, designed by start-up company Bin. E, recognizes different types of waste via a system put inside the bin which uses sensors, image recognition and artificial intelligence. Once waste is placed inside, the camera and sensor recognize its type and place it in one of the smaller bins. Then it compresses (压缩) the waste so it occupies less space.
It is thought that the bin could be stocked by department stores such as John Lewis, which said it is introducing more new hi-tech recycling bins. Matt Thomas, a buyer at John Lewis, gave us the reason, “We’ve recently seen a jump in specialist bins sales, with a 25 percent increase in the last few months alone. We have noticed our customers are becoming more and more focused on sustainability. In response to this demand, we are really excited to introduce a smart bin this autumn or winter season designed to make recycling more efficient and functional for the everyday home.”
Bin. E’s official release on the market will take place next year. However, at first only a larger version designed for offices will be available. The office bin will sell at ￡430 while customers will need to pay a ￡107 subscription fee for an accompanying smartphone app, which hooks them up with collection services. A spokesman at Bin. E said that home version of the bin will be cheaper and will not include a monthly payment.
They added, “After the office version, we plan to create an outdoor version and later the home version. We decided to go for the outdoor version for public areas first because it is more difficult to organize an efficient waste segregating system than in our homes.”
1. What do we know about a new “smart bin” from the first paragraph?| A．It is easy to operate. | B．It works automatically. |
| C．It is very expensive. | D．It has been used widely. |
| A．The company. | B．The sensor. |
| C．The camera. | D．The bin. |
| A．To change people’s behavior. | B．To make them more famous. |
| C．To popularize new technology. | D．To satisfy increasing demands. |
| A．At home. | B．In the supermarket. |
| C．In the office. | D．In the open air. |
【推荐3】As we face climate change, a new digital tool helps expand carbon-free energy without damaging the wildlife habitats. In Maine, the Renewable Energy Siting Tool is a newly released map that allows the clean energy developers to identify the sites for solar and wind projects while avoiding those with sensitive wildlife habitats. Sarah Haggerty, the lead developer, notes that the tool came into being thanks to the data provided by Maine’s Depar-ment of Environmental Protection, state biologists, clean energy developers, as well as financial support from the bank.
Based on data on land-use, habitats, energy resources, etc., the tool uses a traffic-light model to identify sites suitable for development and sites to avoid. Fields like landfills are shown in green, wetland areas or rare species habitats are shown in red, while yellow shown areas indicate that closer examination of project impacts is necessary.
The tool was developed after Maine passed a law requiring that 80% of Maine’s electricity come from renewable resources by 2030. Haggerty says, “We are in urgent need of this tool to help us fight climate change in a way that reduces impact on our valuable natural resources.” Maine is the most forested state in the nation, and agriculture, natural resources, and nature tourism play important roles in its economy. Yet the state is among the top five in losing its farmland to development. It makes little sense to develop clean energy projects at the expense of farmland.
When developers announce a clean energy project, they often face disagreement from community members who are concerned about the loss of valuable farmland or the impact on wildlife. This can discourage investors and slow the transition to renewable energy. Luckily, this tool can help developers speed up the development of clean energy by quickly identifying suitable land. Clean energy development needn’t come at the expense of wildlife.
1. What is the second paragraph mainly about?| A．How the new tool works. | B．How the new tool is adjusted. |
| C．How the new tool is developed. | D．How the new tool collects data. |
| A．To protect Maine’s renewable resources. | B．To apply clean energy to wildlife habitats. |
| C．To improve the effective use of clean energy. | D．To balance clean energy and wildlife habitats. |
| A．Skeptical. | B．Tolerant. |
| C．Conservative. | D．Positive. |
| A．A news review. | B．A science magazine. |
| C．A travel brochure. | D．A geography textbook. |
【推荐1】There’s no tune, no lyrics and you can’t dance to it. Don’t let that put you off white noise is the music industry’s next big thing. Streaming services have seen an explosion of tracks in the last year consisting entirely of recordings of rainfall, ocean waves and winds.
Some of the recordings have earned their creators millions of pounds. Record companies and tech firms have taken notice. Apple is including background noise in its next operating system, and TikTok has been promoting pink noise and brown noise — sounds with lower frequencies as an aid to concentration for students at the start of the school year.
Noise fans say that studying, sleeping and meditation(冥想)are all enhanced by listening to these sounds at proper levels. The economics of music-streaming mean noise-makers can cash in. Someone falling asleep to White Noise Baby Sleep’s 90-second track Clean White Noise on repeat for seven hours will win up 280 plays. So far it has been played 837 million times, worth an estimated $2.5 million in royalties(版税). The lead track on Spotify’s own Rain Sounds playlist, two minutes of rainfall, has more than 100 million plays. In contrast, Laura Mvula only has 541,000 Spotify streams for the title track of this year’s award-winning album, Pink Noise —not a slice of sleepiness but tuneful, lyrical dance-pop that took her three years to make.
Spotify, Apple Music, and other streaming services pay royalties in roughly the same way. They set aside a sum of money for royalties, which is then divided up between distributions, record labels, recording artists and songwriters. That means that Mvula will get a smaller slice of the Spotify pie than will White Noise Baby Sleep, while most of it goes to the major record companies.
It’s hard to work out who is making such noise. Spotify lists White Noise Baby Sleep’s songwriting credits as belonging to an Erik Eriksson. It’s not obvious who Eriksson is or whether he is part of a larger organization, but the Medium website One Zero last year established that many of the artists’ names are pseudonyms(假名)used by companies.
1. Which of the following best describes white noise?| A．Harmonious. | B．Confusing. | C．High-priced. | D．Profitable. |
| A．By presenting some statistics. | B．By making classifications. |
| C．By using quotations. | D．By giving a definition. |
| A．To show white noise is more popular. |
| B．To demonstrate pink noise has gone out of date. |
| C．To indicate how Mvula gets paid. |
| D．To exhibit who makes huge profits. |
| A．Tips for attracting more white noise fans. |
| B．Challenges some companies are faced with. |
| C．Difficulty in identifying the copyright holders. |
| D．Ways to improve the qualities of credits. |
【推荐2】Snowbirds are people who leave their homes when the temperature drops and head to warmer climates. They are mostly retirees and business owners who can afford to take the winter off. While the snow flies in the Northern states, they are enjoying golf, sailing and barbecues in mild temperatures in the South. Then, after winter passes, they return to their homes in the North.
Most snowbirds are away from Canada and the Northern states between the middle of October and the end of November. They pack up and head to Florida, Alabama, Texas, California and all of the other Southern states. Some may even go as far as Australia or Italy to escape the cold winter weather. There are special communities for snowbirds in many areas. Snowbirds are also offered special discounts in some restaurants, hotels and area attractions. Several states even have special snowbird resorts. There are several online communities and local resources to help snowbirds get set in their seasonal homes.
Some snowbirds own homes both in the South and in the North. Both homes have everything they will need for their stay minimizing the amount of packing necessary when moving from one to the other. Other snowbirds will rent apartments for the duration of their stay outside of their home state.
Recreational vehicles, or RVs, are a huge part of the snowbird lifestyle. RVs allow snowbirds to move from place to place on a whim, bringing everything they need with them. They spend nights in RV parks, large parking lots or anywhere else they choose to stay. RVs have beds, bathrooms and most other modern conveniences available in a regular home. Although the spaces are small, there is more than enough room for a couple to live in.
1. Which of the following can be regarded as a snowbird?| A．One who retires and has a lot of free time. |
| B．One who likes to play in snow in winter. |
| C．One who travels around the world the whole year. |
| D．One who heads for the South to avoid the cold weather. |
| A．the Internet makes it easier for snowbirds to find seasonal homes |
| B．snowbirds are not welcome in many areas |
| C．snowbirds have to stay in special communities |
| D．it doesn't cost much to be a snowbird |
| A．avoid the heavy traffic | B．carry everything they have at home |
| C．have a comfortable life wherever they are | D．save more money than renting an apartment |
| A．one has to be quite wealthy to be a snowbird |
| B．Canada is a favorite destination for snowbirds |
| C．snowbirds don't like the weather in the North |
| D．a snowbird has to own homes both in the South and in the North |
【推荐3】The amount of plastic pollution in the oceans is rapidly increasing. This is problematic, as at least 700 kinds of ocean animals — including sharks, whales, seabirds and turtles — can become caught in the stuff or mistake it for a tasty snack.
While we know that some ocean animals seem to catch plastic because it looks like jellyfish or some other food sources, less research has been carried out into what plastic smells like to ocean animals. But now, a study from the University of North Carolina at Chapel Hill has found the coating (涂层) that naturally builds up on ocean plastics causes the rubbish to give off the smell of food.
The researchers took 15 turtles, each around five months old, and placed them in a lab aquarium. They then piped in smells of clean water, clean plastic, turtle food, and plastic that had been soaking in the ocean environment for five weeks. The turtles showed no reaction to the smells of clean water or clean plastic. But when facing ocean soaked plastic or turtle food, they stuck their noses out of the water and showed increased activity.
“This finding is important because it’s the first proof that the smell of ocean plastics causes animals to eat them,” said Dr Kenneth J Lohmann, who took part in the study. “It’s common to find a turtle with its stomach full of plastic materials. There are also increasing reports of sea turtles that have become ill and stuck on the beach due to their taking in plastic.”
According to the researchers, areas of the ocean with much plastic may trick turtles and other animals into thinking that there are plenty of food sources, when the opposite is true. “Once these plastics are in the ocean, we don’t have a good way to remove them or prevent them from smelling like food,” said Lohmann. “The best thing we can do is to keep plastic from getting into the ocean at all.”
1. Why is plastic pollution posing a threat to ocean animals?| A．It may mislead them as food. | B．It may eat up all jellyfish. |
| C．It may kill them with its smell. | D．It may trap 700 species of sea animals. |
| A．Sea water. | B．Clean water. |
| C．Glean plastic. | D．Ocean-soaked plastic. |
| A．Turtles seem to eat plastic because it looks like food. |
| B．Turtles have died out due to their taking in plastic. |
| C．Turtles eat plastic because it gives off the smell of food. |
| D．Turtles with their stomachs full of plastic were studied. |
| A．Keep away from the polluted ocean. | B．Maintain a plastic-free ocean. |
| C．Remove plastic from the ocean. | D．Stop people feeding turtles plastic. |
| A．Entertainment | B．Literature |
| C．Health | D．Science |
