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Build an Attention-Grabbing Bicycle Light

Projecting light onto the ground makes a bicyclist easy to spot

4 min read
Photo of the author cycling at night.
Photo: Grace Schneider

Photo of the author cycling at night.I’m Cycling Here: Drivers find it hard to spot bikes at night. IEEE Spectrum senior editor David Schneider built a flashing lighting rig to clearly mark his lane.Photo: Grace Schneider

I live less than a mile from the campus of the University of North Carolina, in Chapel Hill. Not surprisingly, many of the nearly 30,000 students enrolled there get around town on bicycles, day and night. I bike, too, but seldom do I go out after dark: I fear it’s just too dangerous.

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
Photo of Jacob Ziv
Photo: Rami Shlush

Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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