Archive for February, 2005

Recycling high-tech

February 23rd, 2005 by dstmartin

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What happens when your new computer hits retirement age? Recycling high-tech. Today, on Engineering Works!

We can do so many cool things with our new computers that we never stop to think about what to do with them when they get old. Engineers are thinking about it a lot these days.

From the monitor to the hard, drive, your computer is full of hazardous waste waiting to happen. Listen to this list – antimony, arsenic, cadmium, hexavalent chromium, lead, mercury, polyvinyl chloride. More than eight-and-a-half-million tons of potentially hazardous stuff over the last 20 years or so.

Engineers are working on the problem from both ends. Before computers go into production, and after you get rid of them. Design engineers at one major computer maker now check out how materials in the new machine can be recycled and how long it takes to take one apart for recycling – before it ever goes into production.

They’re also working out how to make it easier to take apart the new computer so it’ll be easier to recycle. Plastic is more difficult to recycle than metal, so some manufacturers are replacing plastic components with metal and cutting down on the different kinds of plastic. Different kinds of plastic need different processes to recycle, you know.

It isn’t just computers. We toss out about 100 million cell phones every year with a lot of the same problems as computers.

It’s time for us to get out of here before somebody recycles us.


Venus Flytraps

February 16th, 2005 by dstmartin

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Today, we’re going to look into a Venus Flytrap. What’s that got to do with engineering? We’ll find out on Engineering Works!

Everybody knows about Venus Flytraps. They’re those bloodthirsty plants that grab careless bugs and eat them. A team of mathematicians, biologists and engineers has figured out how they do that. But why should anyone – especially an engineer – care how a plant catches a bug?

Many plants move. Slowly. Think of sunflowers turning to face the sun. But Venus flytraps move fast, and knowing that could be very useful.

The answer has to do with how Venus flytraps’ leaves are shaped and how they’re built. Something, researchers don’t know what puts stress on the leaves. Like stretching a rubber band. So the leaves stretch. Just a little. And hold it, and hold it — until a careless fly brushes a tiny hair on the inside of the leaves. Then the leaves snap together. Like what happens when that rubber band breaks. Goodbye fly.

This fascinates engineers exploring a new field called micro-fluidics. That’s controlling the flow of very small amounts of liquids and gases. Micro-reactors to produce tiny quantities of dangerous or expensive chemicals, lab-on-a-chip biochemical sensors, hand-held systems to detect trace amounts of air borne pollutants. A raindrop is big in the world of micro-fluidics. When you’re dealing with such tiny quantities, you have to be able to do things very quickly. Like a Venus flytrap.

It’s time for us to snap on out of here.


The Chunnel

February 9th, 2005 by dstmartin

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All aboard! We’re going to take a train ride under the English Channel, today on Engineering Works!

The English Channel has separated Great Britain from the continent of Europe for 12,000 years. You had to ride a boat or an airplane to get from England to France. That changed when the Chunnel opened in 1994.

The chunnel, short for channel tunnel, is one of the marvels of modern engineering and construction. It’s 32 miles of concrete and steel deep under the floor of the English Channel. Boring machines two football fields long chewed toward each other from England and France and met in the middle — as much as 250 feet a day.

The chunnel is actually three concrete tunnels. Two carry trains. The third gets maintenance workers where they need to be and gives train passengers an escape route in case of an emergency. It works. Everyone escaped safely when a train caught fire soon after the tunnel opened.

When the tunnel was finished, it was the most expensive construction project ever. Twenty-one billion dollars. That’s 700 times what it cost to build the Golden Gate Bridge.

Now, trains speed through the tunnel as fast as 100 miles an hour. Crossing the channel is a 20-minute trip. And it’s paying off for the company that built it. The first five years the Chunnel was open, it carried 28 million passengers and 12 million tons of cargo between England and France.

We’re pulling in already. See you next time.


Atomic Clocks

February 2nd, 2005 by dstmartin

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We’re going to do this one on time. Come along with us as we figure out how. Atomic clocks, today on Engineering Works!

Time never stops. We’ve been keeping track of it for a long time, and we’ve done it a lot of different ways – sundials, dripping water, candles with marks on them, springs and gears and pendulums, quartz crystals and electricity.

All of these timekeepers have one thing in common. They keep track of the interval between one tick and the next. And they all have a problem — the same problem. The intervals they measure aren’t always the same. They’re probably not that different, but they vary — a little or a lot. If you need to measure time exactly — to navigate a space probe or use a global positioning system – they’re not good enough.

This is where special clocks called atomic clocks come in. Instead of pendulums and gears or even quartz crystals, atomic clocks use the vibration between the nucleus and electrons of atoms — usually cesium atoms — to set the interval we use to measure time passing. Even this interval varies a little. But not much. The atomic clock at the Naval Observatory near Washington, D.C., is accurate to within about one second in 20 million years.

If you think this is accurate, clocks based on hydrogen atoms do even better over the short term. But over longer periods of time, cesium is better.

Time’s up. We’ve got to go now.