Archive for April, 2004

Spies like us

April 28th, 2004 by dstmartin

Get out your cloaks and daggers and sneak along with us. We’re going to see where James Bond gets those nifty gadgets. Real-life spy stuff – today on Engineering Works!

Most of the sneaky spy things you see in the movies come straight out of Hollywood’s imagination. But the Central Intelligence Agency has a whole division of scientists and engineers, turning out gadgets not even James Bond could pass up.

How about this one – monitoring devices that looked like, well, like tiger droppings. Placed along jungle trails in Vietnam, they provided valuable information about enemy troop movements.

Back in the 1970s, the CIA engineers designed a tiny camera intended to be strapped to pigeons and flown over urban targets. Nobody notices pigeons in the city, right? It took a couple of tries to get it right. The first camera was so heavy the pigeon ended up walking home. Things have changed since then. Now satellites take pictures that are better than the ones the pigeons got.

Then, only a few years ago, a realistic robotic catfish known as Charlie swam onto the spy scene. CIA officials aren’t saying, but experts guess that Charlie might be used to take water samples from rivers near suspected chemical or nuclear weapons plants.

The CIA keeps these gadgets and more in a top secret spy museum. The agency celebrated its 40th anniversary by giving outsiders a glimpse.

Oh, well. We’ll just sneak away ’til next time.

Stay hot & cold with a thermos

April 21st, 2004 by dstmartin

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They say that some people run both hot and cold. Here’s an invention engineered to do that – on purpose — the thermos bottle. Today on Engineering Works.

It keeps the milk cold in your kid’s Spiderman lunch box and a construction worker’s coffee hot ’til break time. It’s the thermos bottle – an insulated container with a screw-on cap that’s a cup. Remember yours from grade school?

Maybe you took your thermos apart to find out how did it know when to keep things hot or cold? But there’s nothing magic about a thermos. It works simply by slo-o-w-ing down temperature changes – so hot liquids don’t cool off, and cold liquids don’t warm up.

Let’s take a look inside a thermos. That shiny thing is the liner, where you pour whatever beverage you want to drink later. Don’t drop it – it’s glass. The outer case – the one decorated with your favorite superhero – protects it. The liner looks kind of like a mirror, to keep heat from radiating out.

What you can’t see is that the liner has two walls. The space between them is filled with – nothing, not even air. It’s a vacuum – the best insulator there is. This makes it hard for heat to move in or out of the thermos.

Your coffee won’t stay hot forever in a thermos, but it will be just the temperature you like with your donut at the office.


Dazzling Doppler

April 14th, 2004 by dstmartin

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We’re going to listen to a sound that fascinated an Austrian scientist 150 years ago. Today on Engineering Works.

We may not remember what it’s called, but we’ve all experienced something called the Doppler effect. It’s the change in the pitch of the sound of a locomotive as it goes by you. Or maybe the sound of an ambulance siren as it comes toward you and then goes away. That’s the Doppler effect, too. Austrian physicist Christian Doppler discovered it 150 years ago.

That change happens because the sound waves you hear as the ambulance comes toward you get squeezed together in the air, just a little. Then as it goes away, the sound gets stretched. The squeezing and stretching changes what it sounds like.

This may sound like just physics trivia, but engineers are putting the idea to work in important ways. Doppler radar, for instance, uses the same idea to watch the winds inside big thunderstorms. If part of the wind is blowing toward the radar and part away from it, that means the wind is spinning. And that means a tornado.

Doctors use Doppler ultrasound to find problems in the way your blood circulates through your heart and arteries. The Doppler effect lets them look at how fast blood flows and in what direction. If there’s a problem, the Doppler effect helps the doctors see it.

Our problem is we’re out of time.