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5 Things You Can Use if You Run Out of Cash

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Civilizations have been creating currencies since the dawn of history. A pure barter system always has deficiencies, not least of which is transporting goods over mountains, through valleys, and across oceans. Think of the human effort involved in a simple transaction—not to mention the manure abatement fees—on ox-drawn wagons. So, to make transactions a bit simpler, almost all civilizations have come up with currencies.

1. Shells

From China to Africa to the Americas, shells were used as a medium of exchange. Whether small cowry shells or larger conchs, gathered in bags or tied together to form belts, shells held value in ancient cultures. Most shells used for currency throughout the world were not large decorative items, but small, transportable, and rather unremarkable specimens. In some cultures, the time and effort spent on tying the shells together to form belts, necklaces, and tapestries contributed to their value. Shells were so predominant as a currency that some of the first real coins minted in China were bronze pieces cast in the shape of small shells.

2. Feathers

Let's face it, it's tough out there being a chief, especially on a small Pacific island where the resources are scarce and the people are hungry. The only way to project power is by wearing a pimp-tastic feather cape that conveys authority. Feathers, then, became a prized commodity in many island societies of yore. Eventually, however, feathers themselves were being used very little in the decorative arts and instead became a mode of exchange. As recently as the 1970s, some small island communities were still using feathers bound together in plates in intra-island trading.

3. Chocolate

chocolate-drizzleIn Mesoamerican cultures the cacao bean, from which we get chocolate, was the primary form of currency in the pre-Columbian era. The small, rather plain looking little pods had a pretty regular exchange rate throughout Mayan civilization in which you could buy a tamale for a few beans or the pleasure of a lady's company for 10. The beans were so valuable that the unscrupulous went through the effort of making counterfeits by shaving down avocado pits. When the Spanish invaded, it took decades before they appreciated the delights of chocolate. They preferred the silver and gold of Central and South America for their currency.

4. Wampum

OK, to be fair, wampum could be lumped into the "shells" category, but it wouldn't have told the whole story. Wampum is a general name for a variety of shell beads that were produced by Native Americans from the 16th to the 18th centuries. Between various tribes and groups, wampum was exchanged to commemorate treaties, marriages, and grand occasions. The beads were often tied together in intricate belts that created pictures, told stories, and basically acted as a memory aid in the oral tradition. It was not until contact with the Europeans that the beads actually became currency unto themselves. Some of the colonies strictly monetized the beads and created a specific exchange rate between wampum and Dutch stuivers, or Spanish reales. Eventually, Dutch colonists started more industrial manufacture of the beads and wound up demolishing the market with overproduction.

5. Abalone

currencySometimes you don't have to look back in history to find examples of interesting currencies. The abalone, a rather rare mollusk, has been poached almost to extinction. Like many endangered creatures, its value as a food source greatly outweighs its actual tastiness. Its shell is valued for its iridescent shimmer that is a primary source of mother of pearl. The gastropods are so valued in Asia, however, that Chinese gangs are reported to be using the chewy creatures as trade for shipments of drugs, guns, and other contraband material.

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iStock // Ekaterina Minaeva
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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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Name the Author Based on the Character
May 23, 2017
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