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By David B. Gleason from Chicago, IL - The Pentagon, CC BY-SA 2.0, Wikimedia Commons

9 Amazing Facts About The Pentagon

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By David B. Gleason from Chicago, IL - The Pentagon, CC BY-SA 2.0, Wikimedia Commons

The Pentagon, home to the U.S. Department of Defense, is a remarkable building—and has been since ground was broken on its Arlington, Virginia site 75 years ago, on September 11, 1941. Within three months, the U.S. would declare war on Germany, Italy, Japan, and their allies, and by 1945 the Pentagon would be home to the most powerful military in the world.


Okay, you know this already, but how big is enormous? About 6.6 million square feet. More than 17 miles of corridors. A five-acre central plaza. It’s only 77 feet above ground (five stories), but each of its five sides is 921 feet long, which means a lap around the outside of the building is almost a mile, which may make it easier to understand why in the early years—before there were telephones at every desk, and before email—some messengers took to the hallways on roller skates. When finished in 1943, the Pentagon became the largest office building in the world, and it’s still one of the biggest.


Because it was built in sections, by the end of April 1942—a mere eight months after the first batch of concrete was poured—employees were moving in. On January 15, 1943, thanks to a multiple-shift, 24-hour-a-day construction schedule, it was complete.


There was such pressure to build quickly—there was simply not enough office space for the thousands of military personnel flooding into Washington after Pearl Harbor—that construction on parts of the building often began before blueprints and other design documents were finished, despite there being about 1000 architects designing the building onsite.


By U.S. Army Corps of Engineers, Public Domain, Wikimedia Commons

It seems fitting that the choice of building material for the Pentagon was informed by a war shortage. Because of World War II, which had been going on in Europe for two years before construction began, steel was in short supply. Because steel is needed to build high, the Pentagon was designed to be short. The primary building material? Concrete, comprised, in part, of 680,000 tons of sand and gravel from the Potomac. Also absent, until recently—elevators, because you need steel to make them. Now, thanks to a massive renovation project, there are 70 of them.


The first site chosen for the building was Arlington Farms, which was pentagon-shaped. But planners figured out that the building would block the view of Washington from nearby Arlington National Cemetery. So another site was chosen (where Hoover Field used to be). By this time, planning was so far advanced that the shape couldn’t be changed. Also, President Roosevelt liked the design—an important factor in keeping the original layout. "I like it because nothing like it has ever been done that way before," Roosevelt said of the design.


“Like a circle, a pentagon would create shorter walking distances within the building—30 to 50 percent less than in a rectangle, architects calculated—but its lines and walls would be straight and, therefore, much easier to build,” wrote Steve Vogel in Washington Post Magazine. In theory, at least, it takes no longer than six minutes to walk between any two spots in the building. According to Vogel, the shape also proved conducive to optimal use of space and utilities, such as electricity and plumbing.


As specified by Virginia state law regarding segregation in public buildings at the time it was built, the Pentagon almost had segregated bathrooms and eating areas. But President Franklin D. Roosevelt had, in June 1941, outlawed discrimination in the defense industry with Executive Order 8802. After Roosevelt visited the partially-completed building in 1942 and noticed a surfeit of bathrooms (284 in all), he may have insisted that there be no separation according to race. This was only one of a number of racial issues that surfaced during construction, according to Snopes


By US Army - NARA, Public Domain, Wikimedia Commons

The year was 1967, and passions against the U.S. military presence in Vietnam were running high. Thousands of protesters marched to the Pentagon, and, as part of a dramatic “exorcism,” tried to lift it off the ground. The attempt failed, because—to begin with, 680,000 tons of sand.

According to Arthur Magazine’s oral history of the event, in the planning stages, military representatives negotiated with the protest leaders, and came to a compromise regarding the liftoff: they could only raise the building three feet, not 22, as originally planned. The military was concerned that lifting it higher would cause major structural damage.


In order to save time during the construction phase, apartments were built onsite for supervisors, and even after completion, one remained. After Captain Robert Furman discovered that his former digs—a small, windowless apartment in the Ordnance Department office bay—remained, he used it to save on hotel expenses during his post-construction visits to Washington. Eventually, higher-ups caught on, and the secret hideaway was dismantled. During his stays there, office workers would see him suddenly emerge with his suitcase, but remained clueless as to why.  “They all wondered what was in that room,” he said.

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iStock // Ekaterina Minaeva
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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Sponsor Content: BarkBox
8 Common Dog Behaviors, Decoded
May 25, 2017
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Dogs are a lot more complicated than we give them credit for. As a result, sometimes things get lost in translation. We’ve yet to invent a dog-to-English translator, but there are certain behaviors you can learn to read in order to better understand what your dog is trying to tell you. The more tuned-in you are to your dog’s emotions, the better you’ll be able to respond—whether that means giving her some space or welcoming a wet, slobbery kiss. 

1. What you’ll see: Your dog is standing with his legs and body relaxed and tail low. His ears are up, but not pointed forward. His mouth is slightly open, he’s panting lightly, and his tongue is loose. His eyes? Soft or maybe slightly squinty from getting his smile on.

What it means: “Hey there, friend!” Your pup is in a calm, relaxed state. He’s open to mingling, which means you can feel comfortable letting friends say hi.

2. What you’ll see: Your dog is standing with her body leaning forward. Her ears are erect and angled forward—or have at least perked up if they’re floppy—and her mouth is closed. Her tail might be sticking out horizontally or sticking straight up and wagging slightly.

What it means: “Hark! Who goes there?!” Something caught your pup’s attention and now she’s on high alert, trying to discern whether or not the person, animal, or situation is a threat. She’ll likely stay on guard until she feels safe or becomes distracted.

3. What you’ll see: Your dog is standing, leaning slightly forward. His body and legs are tense, and his hackles—those hairs along his back and neck—are raised. His tail is stiff and twitching, not swooping playfully. His mouth is open, teeth are exposed, and he may be snarling, snapping, or barking excessively.

What it means: “Don’t mess with me!” This dog is asserting his social dominance and letting others know that he might attack if they don’t defer accordingly. A dog in this stance could be either offensively aggressive or defensively aggressive. If you encounter a dog in this state, play it safe and back away slowly without making eye contact.

4. What you’ll see: As another dog approaches, your dog lies down on his back with his tail tucked in between his legs. His paws are tucked in too, his ears are flat, and he isn’t making direct eye contact with the other dog standing over him.

What it means: “I come in peace!” Your pooch is displaying signs of submission to a more dominant dog, conveying total surrender to avoid physical confrontation. Other, less obvious, signs of submission include ears that are flattened back against the head, an avoidance of eye contact, a tongue flick, and bared teeth. Yup—a dog might bare his teeth while still being submissive, but they’ll likely be clenched together, the lips opened horizontally rather than curled up to show the front canines. A submissive dog will also slink backward or inward rather than forward, which would indicate more aggressive behavior.

5. What you’ll see: Your dog is crouching with her back hunched, tail tucked, and the corner of her mouth pulled back with lips slightly curled. Her shoulders, or hackles, are raised and her ears are flattened. She’s avoiding eye contact.

What it means: “I’m scared, but will fight you if I have to.” This dog’s fight or flight instincts have been activated. It’s best to keep your distance from a dog in this emotional state because she could attack if she feels cornered.

6. What you’ll see: You’re staring at your dog, holding eye contact. Your dog looks away from you, tentatively looks back, then looks away again. After some time, he licks his chops and yawns.

What it means: “I don’t know what’s going on and it’s weirding me out.” Your dog doesn’t know what to make of the situation, but rather than nipping or barking, he’ll stick to behaviors he knows are OK, like yawning, licking his chops, or shaking as if he’s wet. You’ll want to intervene by removing whatever it is causing him discomfort—such as an overly grabby child—and giving him some space to relax.

7. What you’ll see: Your dog has her front paws bent and lowered onto the ground with her rear in the air. Her body is relaxed, loose, and wiggly, and her tail is up and wagging from side to side. She might also let out a high-pitched or impatient bark.

What it means: “What’s the hold up? Let’s play!” This classic stance, known to dog trainers and behaviorists as “the play bow,” is a sign she’s ready to let the good times roll. Get ready for a round of fetch or tug of war, or for a good long outing at the dog park.

8. What you’ll see: You’ve just gotten home from work and your dog rushes over. He can’t stop wiggling his backside, and he may even lower himself into a giant stretch, like he’s doing yoga.

What it means: “OhmygoshImsohappytoseeyou I love you so much you’re my best friend foreverandeverandever!!!!” This one’s easy: Your pup is overjoyed his BFF is back. That big stretch is something dogs don’t pull out for just anyone; they save that for the people they truly love. Show him you feel the same way with a good belly rub and a handful of his favorite treats.

The best way to say “I love you” in dog? A monthly subscription to BarkBox. Your favorite pup will get a package filled with treats, toys, and other good stuff (and in return, you’ll probably get lots of sloppy kisses). Visit BarkBox to learn more.