Archive for October, 2004

Pneumatic tubes

October 27th, 2004 by dstmartin
 

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Everything’s going down the tubes, today on Engineering Works!

Sometimes the niftiest gadgets are nothing new. If you use the drive-up window at your bank, you know about one of them. The contraption that slurps up your check and gives you back money. It’s a pneumatic tube, and it’s been around since the Victorian Age, back in the 1800s.

Pneumatic tubes use compressed air to move things. Sort of like a vacuum cleaner in reverse. A puff of air sends them away. Lower the pressure and they come back. In the beginning, engineers thought big pneumatic tubes might be a good way to move freight, even people.

In 1870, inventor Alfred Beach built New York City’s first subway – a 300-foot pneumatic tube big enough to carry wheeled vehicles. It ran for a block from City Hall. City officials decided to build elevated trains instead.

By the early 1900s, underground tube systems in Philadelphia, Chicago, New York and other cities whisked mail all over town faster than a horse-drawn wagon could. The New York Stock Exchange moved orders with pneumatic tubes faster than messengers on foot. And sales clerks in almost every department store traded payments and receipts with cashiers at the other end of pneumatic tubes.

Today, banks, hospitals and some businesses use pneumatic tubes to send things quickly within their buildings. Paperwork. Machine parts. Try sending a bottle of antibiotics over the Internet.
Well, we’re done here.

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DVDs

October 20th, 2004 by dstmartin
 

We’re going to take a look at the way you watch movies. DVDs, today on Engineering Works!

Videotapes seem to be going out of style. A trip to the video store for an evening’s entertainment is more likely to mean a movie on DVD than one on video tape. New movies are all on DVDs – digital video disks. Most of our old favorites, too. And some you can’t get on videotape. So what’s so nifty about DVDs?

Probably the most important thing is that DVDs’ digital signals give you pictures with higher resolution than video tapes. That means they’re sharper, more lifelike. You can play the soundtrack in any one of eight languages. And you can have subtitles in 32. Plus an on-screen index so you can find your favorite scene without rewinding and fast-forwarding. Try doing that with a videotape. You can also format the picture for standard or wide screen TVs.

DVDs look a lot like our old friends, the CD. And they use a system of tiny pits and bumps read by a laser to carry data. But a DVD can hold about seven times as much data as a CD. That means about 133 minutes of high-resolution video, plus digital surround sound for the soundtrack.

Right now, DVDs and their players are more expensive than videotape-based systems, but prices will probably come down.

Hey! Pass the popcorn and sit down. It’s time to start the movie.

Magnetic Personality

October 13th, 2004 by dstmartin
 

Talk about your magnetic personality. This one will sweep you off your feet. Magnetic levitation, today on Engineering Works!

Most of us played with magnets when we were kids. It was fun. Put the north poles of two magnets together and the magnets would jump apart. Put the north and south poles together and they’d snap together.

If you remember that, you already understand most of what makes magnetic levitation work. Why should you care? It could change the way we travel in the future. Engineers are using magnetic levitation, or maglev, to design trains that go faster, quieter and smoother than any, you’ve ever seen.

Running trains with magnetic levitation isn’t a new idea. It’s been around for more than a hundred years. The idea is to use powerful electromagnets to float the train just above a guide rail. Other powerful magnets would push and pull the train along the track – smooth, powerful and fast.

The first commercial maglev train began service in 2002 in Shanghai, China. It runs at about 250 miles an hour and covers a 20-mile route from the city center to the airport in about 10 minutes. Engineers are testing another in Germany.

There’s a catch. It takes a lot of electricity to run a maglev train. And the magnetic track the train rides on is expensive. New superconducting electromagnets will help, and engineers are working on them now.

Our train is ready to pull out now. Talk to you later.

Concrete rocks!

October 6th, 2004 by dstmartin
 

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We’re going to take a hard look at concrete. Today, on Engineering Works!

Take a look around and you’ll see concrete everywhere. The highway you drive your car on. The sidewalk you walk on. The driveway to your house. Probably even the building where you work. It’s the most modern of building materials.

Actually though, concrete has been around a long time. At least since the ancient Romans. The old Romans engineers knew how to use concrete. They built everything with it: bridges; high-rise apartment buildings; the Coliseum and the Pantheon. Sounds a lot like the things we use it for today.

Concrete has been around so long because it’s strong and durable and easy to work with. And you can find the ingredients you need to make it almost everywhere. You need three things to make concrete: cement; aggregate; and water. Aggregate is easy to understand. It’s sand, gravel and rocks. Water is easy, too.

Cement gets complicated. Cement is a mixture of limestone, silicon and maybe a little bauxite and iron, ground almost into dust and heated to more than 2,700 degrees Fahrenheit. Some complicated chemistry happens when it’s heated, and more happens when you add the water. This chemistry turns the cement into an adhesive – a gluelike gel that holds the aggregate together into whatever shape it’s formed into. Concrete.

Wet concrete is also a natural for footprints and people’s initials. It’s time for us to make tracks out of here.

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