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How Do You Steer a Bobsled?

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Now that the Olympics are well underway, you might have developed a few questions about the games' equipment. How does one steer a bobsled? What sort of gear do you need to jump into the competitive world of curling? Let's take a crack at answering some of your most pressing queries.

How do you steer a bobsled?

Bobsled teams careen down an icy, curving track at up to 90 miles per hour, so steering is no small concern. Drivers steer their sleds just like you steered your childhood sleds—by manipulating a pair of ropes connected to the sled's steel runners. The driver also gets help from the rest of the crew members, who shift their weight to aid with the steering.

Why do speed skaters wear glasses?

speed-skating

Speed skaters can fly around the ice at upwards of 40 mph, so those sunglasses-type specs they wear aren't merely ornamental. At such high speeds, it's not very pleasant to have wind blowing in your eyes; it's particularly nightmarish if the breeze is drying out your contact lenses. On top of that, there's all sorts of ice and debris flying around on a speed skating track that could send you on a fast trip to the ophthalmologist.

Some skaters also say the glasses help them see the track. American skater Ryan Bedford recently told the Saginaw News that his tinted shades help him focus on the track and filter out distracting lights and camera flashes from the crowd.

What kind of heat are the biathletes packing?

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As you might guess, there are fairly strict rules governing what sort of rifles biathletes carry on the course. They are equipped with guns chambered for .22 LR ammunition. The gun must weigh at least 3.5 kilograms without its magazines and ammunition, and the rifle has to have a bolt action or a straight-pull bolt rather than firing automatically or semi-automatically.

Is a curling stone really made of stone?

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You bet it is, and it's not just any old stone, either. Curling enthusiasts swear by a very specific type of granite called ailsite that is only found on the Scottish island of Ailsa Craig. Ailsite supposedly absorbs less water than other types of stone, so they last longer than their competitors.

Ailsa Craig is now a wildlife sanctuary, so no new ailsite has been quarried since 2002. As a result, curling stones are incredibly expensive. Kays of Scotland, which has made the stones for every Olympics in which curling has been an official event, gets prices upwards of $1,500 per stone.

What about the brooms?

The earliest curling brooms were actual brooms made of wood with straw heads. Modern brooms, though, are a bit more technologically advanced. The handles are usually made of carbon fiber, and the heads can be made of synthetic materials or natural hair from horses or hogs. Synthetic materials tend to be more common now because they pull all of the debris off of the ice and don't drop the occasional stray bristle like a natural hair broom might.

What are the ski jumpers wearing?

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It may look like a ski jumper can pull on any old form-fitting bodysuit and hit the mountain, but things are a bit more complicated than that. Their suits have to be made of a spongy material and can't be thicker than five millimeters. Additionally, the suits must allow a certain amount of air to pass through them; jumpers wearing suits without sufficient air permeability are disqualified. (This rule keeps jumpers from wearing suits that could unfairly act as airfoils.) These rules are seriously enforced, too; Norwegian skier Sigurd Petterson found himself DQed at the 2006 Torino Games due to improper air permeability.

Those aren't the only concerns, though. In 2010, judges disqualified Italian jumper Roberto Dellasega because his suit was too baggy.

What's up with the short track speed skaters' gloves?

skate-gloveIf you watch a bit of short track speed skating, the need for gloves quickly becomes apparent. When the skaters go to make passes or careen around a turn, they need the gloves to keep from cutting their hands due to incidental contact with other skaters' blades.

There's more to the gloves than just safety, though. Since the skaters' hands often touch the ice during turns, they need hard fingertip coverings that won't add friction and slow them down. The tips can be made of any material as long as it's hard and smooth, but you've got to give American skater Apolo Ohno some style points for the gold-tipped left glove he broke out in 2010.

This post originally appeared in 2010.

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iStock // Ekaterina Minaeva
technology
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Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Stephen Missal
crime
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New Evidence Emerges in Norway’s Most Famous Unsolved Murder Case
May 22, 2017
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A 2016 sketch by a forensic artist of the Isdal Woman
Stephen Missal

For almost 50 years, Norwegian investigators have been baffled by the case of the “Isdal Woman,” whose burned corpse was found in a valley outside the city of Bergen in 1970. Most of her face and hair had been burned off and the labels in her clothes had been removed. The police investigation eventually led to a pair of suitcases stuffed with wigs and the discovery that the woman had stayed at numerous hotels around Norway under different aliases. Still, the police eventually ruled it a suicide.

Almost five decades later, the Norwegian public broadcaster NRK has launched a new investigation into the case, working with police to help track down her identity. And it is already yielding results. The BBC reports that forensic analysis of the woman’s teeth show that she was from a region along the French-German border.

In 1970, hikers discovered the Isdal Woman’s body, burned and lying on a remote slope surrounded by an umbrella, melted plastic bottles, what may have been a passport cover, and more. Her clothes and possessions were scraped clean of any kind of identifying marks or labels. Later, the police found that she left two suitcases at the Bergen train station, containing sunglasses with her fingerprints on the lenses, a hairbrush, a prescription bottle of eczema cream, several wigs, and glasses with clear lenses. Again, all labels and other identifying marks had been removed, even from the prescription cream. A notepad found inside was filled with handwritten letters that looked like a code. A shopping bag led police to a shoe store, where, finally, an employee remembered selling rubber boots just like the ones found on the woman’s body.

Eventually, the police discovered that she had stayed in different hotels all over the country under different names, which would have required passports under several different aliases. This strongly suggests that she was a spy. Though she was both burned alive and had a stomach full of undigested sleeping pills, the police eventually ruled the death a suicide, unable to track down any evidence that they could tie to her murder.

But some of the forensic data that can help solve her case still exists. The Isdal Woman’s jaw was preserved in a forensic archive, allowing researchers from the University of Canberra in Australia to use isotopic analysis to figure out where she came from, based on the chemical traces left on her teeth while she was growing up. It’s the first time this technique has been used in a Norwegian criminal investigation.

The isotopic analysis was so effective that the researchers can tell that she probably grew up in eastern or central Europe, then moved west toward France during her adolescence, possibly just before or during World War II. Previous studies of her handwriting have indicated that she learned to write in France or in another French-speaking country.

Narrowing down the woman’s origins to such a specific region could help find someone who knew her, or reports of missing women who matched her description. The case is still a long way from solved, but the search is now much narrower than it had been in the mystery's long history.

[h/t BBC]

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