Archive for August, 2004

Plugging into power grids

August 25th, 2004 by dstmartin

We’re going to tap into the power, today on Engineering Works!

It’s easy to take electricity for granted. Hit the switch and electricity does neat things — brings us news and entertainment on TV, cooks our food, lights our way in the dark. Even keeps us cool in the summer.

Getting us the electric power that makes these conveniences possible is pretty complicated. Except for Texas, the United States is divided into two huge power networks — one in the East and one in the West — generating stations, transformers and transmission lines. Engineers call them power distribution grids. They’re how electricity gets from there to here.

Texas has its own distribution grid. That’s a story for another time.

These grids allow power companies to sell electricity when they have extra or buy it when they need extra. A complicated system of controls keeps it balanced.

This is a good thing. But it’s a bad thing, too. Because if the controls fail just right – or wrong – a power outage in one part of the grid can end up blacking out millions of people across the rest of it. That’s what happened in 2003, when a power failure in Ohio blacked out a big part of the northeastern United States for several days.

Power engineers spent months looking into exactly why it happened, and they’ve developed safeguards that should keep it from happening again.

Our power is on today, and we hope yours is, too.

Modern-day pirates

August 18th, 2004 by dstmartin

Listen to the episode

Heave-ho, me hearties! We’re going to hunt some modern-day pirates, today on Engineering Works!

Some of the most dangerous pirates around these days don’t sail the high seas. They cruise cyberspace. And they can be pretty vicious with a computer keyboard.

These pirates don’t cruise for gold and jewels. The booty they’re after can be worth lots more – information, digital music, video games, movies, corporate documents.

New-fangled pirate-hunters are on the prowl, too. They’re engineers, computer scientists and lawyers. They’re using new laws and new ways of handling valuable digital information to foil the pirates or track them down and catch them before they can get away with it.

These new pirate-hunters fight the pirates with what they call active and passive security methods. Active security is stuff like digital encryption – making it impossible for anyone who doesn’t have the key to get at the information – to keep pirates from stealing the valuables.

Passive security is techniques like so-called digital watermarks – special information hidden inside the stolen data – that pirate-hunters can use to track the stolen stuff and prove who it really belongs to.

It’s more complicated than it sounds. The pirate-hunters need to make it hard for the pirates to steal the information. But they can’t make it too hard for people who have the information legitimately to use it. If it’s too hard – or too expensive – they might turn into pirates themselves.

It’s time for us to sail off into cyberspace. All our digital valuables are ours, we promise.


A Brighter Future

August 11th, 2004 by dstmartin

Listen to the episode

How many engineers does it take to make a better light bulb? We’ll find out today on Engineering Works.

The round incandescent light bulb we all know hasn’t changed much since Thomas Edison invented it 125 years ago. Thin wires, called filaments, inside the glass bulb glow when electricity zips through them. That glow gives us light to see by. But there’s a hitch. Only about a tenth of that energy gives us light. The rest just heats the bulb so we can burn our fingers. Ouch!

Fluorescent lights – those long tubes that light offices and other commercial spaces – appeared in 1938. Instead of filaments, fluorescent tubes are filled with a gas that glows when electricity passes through it. They’re lots more efficient.

Fluorescent lights are cool. Really. They don’t get hot, and they need just one-fourth the energy incandescent bulbs need to produce the same amount of light. And fluorescent bulbs last 10 times longer than incandescent ones. They had problems, though. They didn’t fit a lot of places regular light bulbs did. And they hummed.

Then, compact fluorescent lamps entered the picture in the 1980s. They solved a lot of the problems regular fluorescents had: they screw into regular light sockets; they’re small enough to fit most places a conventional bulb will fit; they don’t hum; and they’re as stingy with the energy they use as regular fluorescent bulbs.

Guess it’s time to turn out the lights for today.


Bulletproof vests

August 4th, 2004 by dstmartin

Listen to the episode

We’re going to take a shot at understanding how bulletproof vests save lives. Today on Engineering Works!

Everybody knows about armor. You know, the metal suits knights used to thrash around in. You’d expect that kind of armor to stop bullets. Using armor made of cloth to protect yourself from gunshots sounds a little odd. But it works, if it’s the right cloth.

The cloth bulletproof vests are made from is special. It’s woven from plastic fibers called aramids. The best-known is probably Kevlar, made by DuPont. Aramid fibers are hard to break because of the way the molecules they’re made from fit together. And they hardly stretch at all. This is important, because it means that the cloth in bulletproof vests can absorb almost all the energy from that speeding bullet.

Bullets hurt you by transferring the energy they carry to your tissues when they hit. If a bulletproof vest absorbs most of the energy before it gets to you, you don’t get hurt – at least not as badly.

Bulletproof vests work best against pistol-sized bullets. Some vests get help against rifle bullets from ceramic or metal plates. The faster, heavier bullets from rifles break into smaller lighter pieces that the cloth armor can handle.

Engineers also use aramid fibers like Kevlar to design and build other things that have nothing to do with bullets — boat hulls, tires, spacecraft parts, tennis racquets.

Bullets or just a hard serve, aramid fibers are good to have around.