Archive for September, 2004

As seen on HDTV…

September 29th, 2004 by dstmartin

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We’re going to get the lowdown on high-definition TV. Today, on Engineering Works!

If you spend any time in front of your TV, you’ve seen the commercials for high-definition television. They make it sound really neat — pictures so real you could reach in and touch them if you wanted to. But is it really that good?

The good news is, yes, the pictures are that good. The bad news is, yes, this new technology is still really expensive.

The most important difference between conventional TV and HD TV is that HD TV has a resolution, or definition, of between 700 and 1,100 lines per inch. Analog TV has a resolution of about 500 lines per inch. The more lines per inch there are, the sharper and more detailed the picture.

Electrical engineers get this more detailed resolution by using digital signals to send the picture to your TV. We won’t go into the details, but the digital signal carries more information than an analog signal, and you get a better picture. Satellite systems and DVDs already use digital encoding, but it’s converted into analog format so you can view it on your analog TV.

The Federal Communications Commission has told broadcasters they must be able to broadcast HD TV by 2006. We’ll have to buy a converter to change digital signals to analog, or a new television set that can read digital signals.

It’s time for our favorite re-run, so we’ll see you later.


Hoover Dam

September 22nd, 2004 by dstmartin

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We’ll visit an engineering marvel that really is your dam business – Hoover Dam. Today, on Engineering Works.

You’ll find Hoover Dam on the Colorado River, on the border between Nevada and Arizona. When it was completed, in 1935, it was the biggest dam in the world. And it changed the American West forever.

Without the water and hydroelectric power it provides Los Angeles, San Diego and Phoenix, the western end of the Sunbelt might have stopped in Dallas. Without it, Las Vegas would still be a dusty little town in the desert.

Building Hoover Dam was such a big project that it took six construction companies to pull it off. More than 200 engineers and 7,000 workers started on it in 1931. The first step was to move the Colorado River out of Black Canyon. Then they used four tons of dynamite to blast foundations and tunnels into the canyon walls. They started pouring concrete in 1933. When they were done, two years later, the dam stood more than 700 feet above the bedrock. They used enough concrete to pave a two-lane highway from San Francisco to New York City.

The reservoir behind the dam – Lake Mead – is a National Recreational Area that extends more than a hundred miles upstream toward the Grand Canyon. Hoover Dam was declared a National Historic Landmark in 1985 – its 50th anniversary. More than seven million people visit each year.

We’ll wrap up our visit now.


Space Junk

September 15th, 2004 by dstmartin

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We’re going to talk trash like you’ve never seen — space junk. Today, on Engineering Works!

The next time you go outdoors, stop a minute and look straight up in the air. You can’t see it from here, but there’s a whole junkyard floating up above your head. It’s the stuff we’ve left behind from almost 50 years of space exploration.

Think about it. There’s so much junk in orbit up there that nobody knows for sure how much there really is. At least 100,000 pieces of stuff, maybe millions. More than 7,000 of them the size of a baseball or bigger. Some as small as chips of paint. In fact, a lot of it is chips of paint, from rockets and satellites. A few – broken down or worn-out satellites – are as big as washing machines.

Don’t snicker at those orbiting paint chips, either. They don’t sound like much, but they’re moving at more than 17,000 miles an hour. Anything moving that fast can do real damage if it hits something. One chip hit a window on the space shuttle. It gouged a crater as big as your thumbnail. Imagine what one of those dead satellites could do.

Engineers are designing shields to protect against collisions with orbiting junk. It’s a tough assignment – shields have to be strong enough to stop the junk before it hits anything important and light enough to lift into orbit.
Time to take out our trash. See you later.


Fill ‘er up

September 8th, 2004 by dstmartin

Let’s take a look at gasoline – long before the filling station. Today on Engineering Works!

It’s easy not to think too much about gasoline. We try to find the lowest price and fill up. But where does gasoline come from, really? Like they say in the movies, it all starts long ago and far away.

The gasoline we pump today started out a long time ago – millions of years, in fact – as tiny plants and animals floating in the ocean. Eventually, they die and sink to the bottom. There grains of rock and other stuff cover them. Thousands of feet deep, without oxygen. As they’re buried deeper, the pressure builds up, and the heat. In a few million years, you get crude oil.

The oil is trapped in tiny spaces in sandstone or limestone – think of a sponge full of dishwater. Oil producers find these oil-filled rocks and drill into them. It’s complicated and expensive.

The next step is refining the crude oil into other stuff, like gasoline. This process is called cracking. Crude oil contains more than 500 different hydrocarbon molecules. As molecules go, they’re pretty big. Cracking breaks them into smaller ones. It works because these molecules boil at different temperatures. Heat the oil to one temperature with the right catalysts and you get gasoline. Heat it to different temperatures and you get diesel fuel or lubricating oil or something else.

Our gas tank is full now. See you later.

Fuel cell cars

September 1st, 2004 by dstmartin

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Hop in. We’re going to take a ride in a car some experts say could be the car of the future, today on Engineering Works!

The first thing you’ll notice about our ride is that it’s quiet. All you hear is the tires on the pavement and … nothing. It’s quiet. No engine noise. That’s because the motor turning our wheels is electric. Not a gas tank or fuel injector in sight. The power comes from something called a fuel cell that uses hydrogen, a gas that’s the most abundant fuel in the universe, to produce electricity. No fossil fuels; no gasoline shortages; no smelly exhaust.

The idea behind fuel cells has been around for a long time. Since 1839, long before gasoline and long before automobiles. Fuel cells helped power NASA’s missions to the moon, but engineers have only recently begun to think about using hydrogen and fuel cells to power cars and provide electricity for our homes.

Here’s how they work. Hydrogen enters the fuel cell, a sort of gas-tight can, and a chemical reaction takes the atom apart. One part actually becomes an electric current that’ll run an electric motor. Dump what’s left into the atmosphere and you end up with good old H2O, water. No noxious exhaust fumes.

We might have fuel cells in our future. We’ve got a long way to go before they’re really practical: where to get hydrogen cheaply and easily; building a network of hydrogen filling stations; what to do with the leftover water. But engineers are working on it.

Well, gotta go.