Lightweight bridge

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Modern engineers have almost always built bridges from steel and concrete. A new bridge is going high tech. We’ll check it out. Today, on Engineering Works!

The next time you drive across a big bridge, take a look at what it’s made of. Chances are it’s concrete and steel. Just about all of big bridges are. The Brooklyn Bridge. The San Francisco Bay Bridge. The bridge over the Mackinac Strait in Michigan. It makes sense. Put together, steel and concrete are strong and durable, qualities we want bridges to have.

Some engineering researchers in Missouri are looking beyond steel and concrete to more high-tech materials. A composite of glass and graphite fibers mixed in a polymer matrix. Almost like a tennis racquet or golf club. Or your favorite fishing rod. The new material does just about everything engineers need to build bridges. It’s strong, lightweight and durable.

The first one is a short one, only about 30 feet long and big enough to handle pedestrians and light vehicles. It’s built of layers of composite tubes, assembled into a sandwich of beams and flat decks. The engineers fitted it with an array of fiber-optic sensors that will let them keep track of stresses and check for damage or signs of failure.

If everything works the way the engineers think it will, they plan to build three full-scale bridges soon.
We’ve crossed the bridges we came to today, and we’re on the way home. See you next time.
EngineeringWorks! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station. Learn more about engineering. Visit us on the World Wide Web. Engineeringworks.tau.edu.

Radar

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Traffic cops use it to catch you speeding. It’s a lot of other things, too. You got it — radar. Today, on Engineering Works!

Radar — radio detection and ranging — has been around since the 1930s. Radar helped protect English cities against German bombers during World War II. Now, air traffic controllers use it to keep airliners from colliding. Radar images help predict the weather and find tornadoes.

Radar’s name describes how it works. A radio transmitter sends out a beam of radio waves. When they hit something, some are reflected back to a special receiver. The receiver turns the reflected beam into information about direction and distance.

Early radar images were awful — smears of light on a screen. You had to know what you were looking for to make sense out of them. But during World War II, they seemed almost magical. Radar today is different — a lot better. One kind, synthetic aperture radar, or SAR, produces images that are almost like photos. Even non-experts can tell the difference between SAR images of a car and a truck. And this is only the beginning.

Engineers are working on ways to make radar so small it can fit into unmanned aerial vehicles only a little bigger than model airplanes. And automakers are working on even smaller radars that will warn us if someone is driving in our blind spot on the highway.

Someone must be in our blind spot. We’ll get out of the way.

EngineeringWorks! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station. We’re on the World Wide Web, too. Visit us at engineeringworks.tamu.edu.

on, off, on, off

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Get out your magnifiers. We’re going to take a look at the tiny beginnings of the Information Age: transistors. Today, on Engineering Works!

Transistors might be the Rodney Dangerfields of the Information Age. They do the work, but the microchips get the credit. As Rodney might say, microchips wouldn’t be nothin’ without transistors.

Engineers at Bell Laboratories built the first one in 1947. Transistors act as both on-off switches, stopping or starting the flow of electricity, and as modulators or amplifiers, increasing the electrical signal. Think of the dimmer switch in your living room. It turns a light on and off, and dims and brightens it.

In a microchip, engineers put together millions of transistors in a particular pattern that does whatever task the chip is intended to do. Arrange the transistors one way, and you get processors that make calculators calculate and computers compute. A different pattern gives you the chip that keeps time in your digital watch or microwave oven. Maybe you need a sensor to monitor temperatures or detect intruders: design a different pattern and it’s yours.

By themselves, transistors can’t do much. But put together enough of them in the right patterns and you can do big jobs and complex calculations; fast, too. Each transistor switches on and off 100 million times a second.

It’s about time to switch off this week’s Engineering Works! See you next time.

EngineeringWorks! is made possible by Texas A&M Engineering and produced by KAMU-FM in College Station. We’re on the World Wide Web, too. Visit us at engineeringworks.tamu.edu.