Archive for November, 2003

Get out of here!

November 26th, 2003 by dstmartin

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If you hang out around nuclear reactors, SCRAM! means something different than it does other places. We’ll find out what nuclear engineers mean when they tell you to “Scram it!â€? today on Engineering Works!

For nuclear engineers and reactor operators, the word “scramâ€? means something special. It means shut down the reactor – now. Every nuclear reactor in the United States has a big red button called the “scram button.â€? Push it and the reactor shuts down. But why “scram?â€? It all started with a guy with an axe standing on top of the first nuclear reactor ever built.

Scientists and engineers led by Italian physicist Enrico Fermi built it during World War II to do experiments that led to the first atomic bomb. Nobody knew much about how to control what was going on inside reactors. Fermi got an expert lumberjack to stand on top of the reactor with a big axe. The idea was that if something went wrong, the axeman would cut a rope that held up a big piece of cadmium metal. The cadmium would slam down inside the reactor and slow down the reaction enough to get it under control.

Fermi’s signal to the axe man was to shout “SCRAM!â€? – short for Safety Cut Rope Axe Man. The axeman never had to cut the rope. But he was ready.

Time’s up. Let’s SCRAM. We mean, get out of here.


Old McDonald goes high-tech

November 19th, 2003 by dstmartin

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Old McDonald’s farm was never like this. We’ll spy on how satellites and other new technology are helping farmers keep track of their cows and corn — today on Engineering Works!

McDonald never heard of the global positioning system – GPS. But if he was farming these days, he’d probably be using global positioning system technology to keep track of his cows and all the other animals. GPS satellites, computers, new sensors and other high-tech tools are helping farmers “harvestâ€? information from their fields – information they can use to harvest more crops.

Sensors in this cornfield, for instance, are measuring how fertile the soil is.

GPS satellites overhead read where the sensors are, and the farmer’s computer puts the data together and draws a map to show which areas need more fertilizer, and what kind.

Other sensors “seeâ€? where pests are chowing down on tasty crops, and map out where to apply insect killers. It’s all about making farming more efficient, doing the right things at the right time.

If you know exactly how much fertilizer and pesticide you need, and where you need it, you can be sure you’re applying enough without putting down too much. The same technology can also warn you about water pollution and other environmental problems before they get out of hand.

Bet Old McDonald wishes his farm was high-tech.


Smoke Detectors

November 12th, 2003 by dstmartin

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This is one sound just about guaranteed to get your attention. Today on Engineering Works, we’ll listen to why you hear it, even before the smoke gets in your eyes.

So you settled down on the couch to watch “Friends” last night and forgot all about that pot roast you put in the oven. And the hot pad you left sitting on the hot stove. Have no fear, the smoke detector’s here, right? You may be wrong.

Many people do not realize that their detector is old and needs to be replaced. Engineers study smoke detector failures by staging full-scale fires in residences and have discovered that ionization detectors can take more than twice as long as photoelectric types to detect smoldering fires, often a delay of 15 minutes or more.

About 90 percent of smoke detectors in homes and on the market sense fire and smoke by using an ionization chamber. These detect flaming fires faster than others, but they just aren’t as quick to detect flameless combustion like smoldering fires.

The typical smoke detector in stores is probably the ionization type, although the labeling won’t necessarily tell you that. Photoelectric detectors will often be labeled as such, sometimes with wording about optical sensing.

If you don’t know how old your smoke detector is, or it’s more than eight years old, replace it. Have both photoelectric and ionization detectors installed or purchase a combination model. Place detectors in every bedroom and hallway. Change the batteries at least twice yearly and test detectors regularly. Or forgetting about that hot pad might become a baptism of fire.



November 5th, 2003 by dstmartin

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Beep…Beep…Beep… You’ve heard that sound thousands of times. It’s the barcode scanner at your local supermarket. Bar codes are everywhere. We’ll find out how they got there, today on Engineering Works!

In the supermarket, everything from corn flakes to hamburger carries that little label with the black stripes. And the supermarket isn’t the only place you’ll find barcodes. Libraries use barcodes to track the books on their shelves. Hospitals put them on the medications they dispense to patients.

The idea we know as barcodes isn’t new. Some engineering students came up with a primitive version back in the 1930s. But it took until the 1970s to get the system we know today up and running.

That strip of wide and narrow lines is actually numbers in disguise. Barcode readers translate the lines into numbers a computer can understand and link to a six-pack of soda or an antibiotic capsule. Other parts of the 12-digit number can be coded to represent individual brands. Coca-Cola’s number is 049000.

That simple-looking set of black lines can carry a lot of information. If you’re selling stuff in a store, the barcode can speed customers through the checkout line, tell the clerk the price and update your inventory. If you’re a nurse in a hospital, the barcode can confirm that you’re giving the right medication to the right patient and warn you if you’re about to make a mistake.

So keep an eye on that barcode.