Archive for July, 2005

Neutron Activation Analysis

July 27th, 2005 by dstmartin

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The TV show CSI and its spinoffs have turned forensic scientists into pop heroes. We’ll look at how engineers turned science into a tool forensic scientists use to catch the bad guys – today on Engineering Works!

CSI fans know that forensic scientists can find out a lot from tiny bits of stuff at crime scenes – who that hair belonged to; what kind of paint is on that car bumper; where that bit of dirt came from – the little things that trip up the bad guys.

When Gil Grissom confronts the murderer with the bit of hair that belongs to her, he knows what he’s talking about because of a nifty analytical tool called neutron activation analysis.

Neutron activation analysis uses neutrons from a nuclear reactor to show researchers exactly what stuff is made of. Hair, for instance – the stuff of TV and real-life murder mysteries.

Hair is mostly protein, but it also has tiny amounts of trace elements, as many as 14 of them. The elements in your hair will be different from those in our hair. When neutrons hit these elements, the combination in your hair gives off a pattern of radiation that’ll be different from mine. So Grissom knows it was you and not me that done it.

Neutron activation analysis is used in a lot of other things, from archaeology to semiconductor manufacturing, to identify traces of different substances.

We’ve identified that our time is up for now. See you next time.


Decision Science

July 20th, 2005 by dstmartin

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That’s the sound of a good decision in action. We’re going out to the ball game, today on Engineering Works!

We all make decisions all the time. Some, like whether to take a pitch when you’re up 3-0, are harder than others. Engineers get paid to make hard decisions, and they’ve come up with some sophisticated mathematics to help work them out.

It’s called decision science and engineers use it all the time to understand complex decisions – like whether to take that 3-0 pitch. Decision science uses the odds that something will happen, its probability, to help decide what to do in complicated situations. Taking that pitch, for instance.

It’s one of the classic arguments in baseball. Decision science says you take the pitch. Why? Because decades of baseball math show that if the count is 3-0, your chances of getting on base are almost 8 in 10. Even if the pitch is a strike, your chances are still better than 6 in 10. But if you swing – even if you put the ball in play – your chances of getting on base drop to less than 4 in 10.

Engineers apply the same thinking to more serious problems: whether to drill that new oil well; where to locate that new plant; how strong to make that new bridge.

Well, our decision is made, scientifically or not. We’re done for this time and we’re off to the ball game. See you later.



July 13th, 2005 by dstmartin

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The cold war may be over, but nuclear weapons are still around. We’ll look into how engineers are keeping us safe, today, on Engineering Works!

If you thought the risk of nuclear war went away when the Soviet Union turned into Russia and got to be our friend, you’re not paying attention. Remember when India and Pakistan got to talking loudly about their bombs? Pretty scary. And terrorists are threatening to build nuclear bombs and use them to destroy big cities.

Unlikely? Maybe. But nuclear engineers are using diplomacy, technology and old-fashioned detective work to reduce the risk.

Some of them are working with scientists in countries like Libya that want to get out of the nuclear weapons business to help turn military research into nuclear technology that can be used for peaceful purposes. They’re also developing new sensors that will give the alarm if radioactive material comes near them. One kind of new sensor floats in buoys anchored off our coasts. It signals an alarm if it detects radioactive materials hidden in ships that sail by.

Still others use science and investigation to track nuclear materials back to where they came from. Each batch of radioactive material carries atomic fingerprints from the nuclear reactor that produced it. Nuclear engineers analyze those fingerprints and put what they find together with other technical and intelligence information to figure out which reactor it was.

We’ve tracked this week’s show right to the end. See you next time.



July 6th, 2005 by dstmartin

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What would the Fourth of July be without fireworks? Today, we’ll ooh! and ahh! over those spectacular aerial displays, on Engineering Works.

From pom-pom bursts to sparkling flares, there’s nothing like fireworks to captivate a crowd. For centuries, we’ve celebrated royal weddings, baptisms and other special events with lavish productions that light up the night sky. Today fireworks shows set to music have become big entertainment spectacles for sports events, theme parks and holidays.

Your basic firework is a shell, filled with explosive powder and stars – pellets made of metallic salts and other chemicals. The pellets make the shape, and the chemicals in the pellets make the colors. When the powder ignites and bursts – anywhere from 400 to 1,000 feet up – the explosion pushes out the stars. Then the stars themselves explode into the shapes that draw oohs and ahhs – a glittering ring, a weeping willow, a starburst. The pattern you get depends on how you arrange the stars in the shell.

Thanks to advances by experts in pyrotechnics – “fire artâ€? – fireworks get fancier every year. Instead of lighting them by hand, technicians switch on an electric current. They use computers to control the timing of music and fireworks to create displays that seem impossible. With such excitement, it’s enough to keep all eyes on the fireworks show at the Super Bowl unless there’s another … wardrobe malfunction.