Archive for April, 2005

Tracking Gas

April 27th, 2005 by dstmartin

Listen to the episode

We’re going to check on some engineers listening to the wind. We’ll see why, today on Engineering Works!

One of the things that the people who plan for disasters and terrorist attacks worry about most is what’ll happen if a cloud of germs or noxious gases gets loose, either by accident or on purpose. You have to know whom to warn about it and to know that you have to know where it’s going.

In open country, this isn’t a problem. Check which way the wind is blowing and you know where the germs or gases are headed. But in a big city, it’s a big problem. All those tall buildings funnel the wind and the gases or germs they carry in complicated directions. That makes it hard to know whom to warn and what to tell them.

A team of engineers is figuring out what germs or gases will do in the complicated airways of New York City. First, they scattered sensitive sensors around Manhattan – some on rooftops, some strapped to streetlights and some worn by volunteers on the street. Then they let loose a cloud of harmless gas and checked where it went and how long it took to get there.

Now they’re putting together a computer model of what happened. They say that if they can figure out how gas moves in New York City’s complicated air flows, they can figure it out for anywhere.

Someone just let our air out. See you later.



April 20th, 2005 by dstmartin

Listen to the episode

We’re going to listen to every homeowner’s nightmare. Termites. Today, on Engineering Works.

Anybody who’s ever owned a house has horror stories about termites in their house or someone else’s. A single termite colony can be home to 200,000 termites, sometimes as many as 2,000,000. In the southern United States, they’re a big problem. We spend at least $2,000,000 a year to prevent termites from attacking our homes, or controlling them once they’re in.

You’ve probably never wondered how termites decide which piece of wood they’re going to have for lunch. Neither did we. But some engineers and scientists in Australia did wonder. And they think they’ve figured it out. It has to do with what wood sounds like to termites as they chomp into it.

Termites chewing sets up vibrations in the piece of wood they’re eating. Big pieces produce lower sounds than small pieces. And termites seem to like higher pitched chewing sounds better than lower-pitched ones. You can fool the hungry insects into avoiding the smaller pieces of wood they prefer by feeding recorded big-wood vibrations into the smaller pieces.

All this does have a point. The researchers think that knowing how these vibrations affect what termites do could be a start toward understanding how to prevent some termite infestations. And maybe get in the way of the way they reproduce, so they end up with fewer of the hungry pests.

Hmm! That sounds like termite vibrations now. We’ll talk to you later.



April 13th, 2005 by dstmartin

Listen to the episode

Everybody likes big ideas. Here’s a tiny idea that’s really big – nanotechnology. Today, on Engineering Works!

Nanometer, nanoparticle, nanotechnology. Big words to talk about stuff that’s really small. How small? Take a nanometer – that’s something that’s one-billionth, with a B, of a meter across. About one-twentyfive millionth, with an M, of an inch. Doesn’t help much, does it?

Try this. You could fit – five average-sized atoms into a nanometer. You could line up 50,000 nanometers across the end of a hair from your head. A nanometer is really small. Working with stuff that you measure in nanometers is what nanotechnology is all about.

One of the things that engineers find most interesting about nanotechnology is that when you’re measuring in nanometers, things often act differently when they’re different sizes. For instance, nanoparticles made of gold can act quite differently – melt at different temperatures, conduct electricity differently, even be different colors – if they’re different sizes.

Engineers are using gold’s odd nano-behavior to build tiny gold bubbles that could be used to kill cancer tumors. Because the bubbles are hollow, the gold soaks up energy from light. A lot of energy – much more than big chunks. So, inject gold bubbles into a tumor, shine infrared light onto them and they heat up enough to kill the tumor. Engineers and scientists are exploring nanoparticles for everything from building faster computers to cleaning up toxic water pollution.

Our time is shrinking down to nano-scale, so we’ll stop now.


Cosmic Ray Scanners

April 6th, 2005 by dstmartin

Listen to the episode

It’s cosmic rays to the rescue – seriously. We’ll find out how. Today, on Engineering Works!

Here’s a question for you. How would you find a nuclear bomb in the millions of trucks and cargo containers that come into the United States every year? The answer worries anti-terrorism experts a lot. Nobody knows.

Cosmic rays may help. Engineers and scientists at the Los Alamos National Laboratory are building a new sensor that uses cosmic rays to detect uranium or lead used to shield it. In case you’ve forgotten, cosmic rays are streams of particles that bombard the earth all the time from space.

These particles – physicists call them muons – zip right through most things, including you and me. Steel plates hardly slow them down. Ditto for aluminum. They cruise right along until they hit something really dense. Like lead or uranium. Then they bounce, or scatter.

The useful thing about all this is that the particles scatter differently depending on what they hit. Steel scatters differently from lead. Lead scatters differently from uranium. And you can program a computer to tell the difference. You don’t even need a person to interpret an x-ray image. The new sensor should be safer and more sensitive than x-rays, big enough to handle big trucks and cargo containers and fast enough that it won’t cause traffic jams at ports and border crossings.

Our cosmic rays are pretty scattered right now, so we’ll see you later.