Monthly Archives: October 2010

Don't Text on Me

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Semi-interesting snippet in a recent Kottke post. I say semi, in part, because the post is about the bandwidth devoted to Justin Bieber and Lady Gaga, and I’m pretty far from the demographic that gives a rat’s ass about Bieber (stands on virtual porch, shakes fist*), and the few times I’ve heard Lady Gaga’s music, I could not differentiate the songs and the saturation point was quickly reached. So, BFD.

However: We all know printer ink is expensive (more expensive than silver, pound-for-pound). So the calculation showing that transmitting the information by text-message is more than an order of magnitude more expensive than by printed text is an eye-opener. One might even go gaga over such a factoid. (FYI, I don’t text, either. All of my thumb ligament damage is old and Gameboy-related. Tetriiiiiis!)

 

*just as if I were playing Lawnville on some social-networking site

Get a Grip

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Balloon filled with ground coffee makes ideal robotic gripper

Particulate materials have a so-called jamming transition, which turns their behavior from fluid-like to solid-like when the particles can no longer slide past each other.

This phenomenon is familiar to coffee drinkers familiar with vacuum-packed coffee, which is hard as a brick until the package is unsealed.

Pretty neat (other than the part where they talk about a vacuum sucking the air out — it’s the external pressure that forces the air movement.)

Rush Hour, Anytime

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Traffic simulator

I think the ring road is the most accurate; it shows the density fluctuations that appear and is a good match to actual traffic. The other situations have left out some details — I’ve noticed that when a lane closure is upcoming, where people will change lanes varies greatly, even when traffic in both lanes has slowed to a crawl. When that happens, you’re supposed to go all the way to the merge point, and then merge, but many people will force their way into the other lane well before, and some people will simply not let a car into the gap in front of them. In the uphill grade I didn’t see much of the behavior I observe on I-81 in northern Pennsylvania: a truck going 55 mph passing another truck going 54 mph, and screwing a long procession of cars behind them, all of whom want to (and can) do at least 65.

Still, it’s a simulation, and I see there’s a “politeness factor” slider, which I presume controls letting people in rather than someone in the simulation flipping a virtual bird or honking a horn.

Stretching that Hit

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Winning the World Series with math

To figure out just how critical the turns are, Carozza did a calculation comparing the straight-line path with a circle around the bases. A path that follows a circle turned out to be a whopping 25 percent faster.

When Carozza presented his calculation at a colloquium talk in the math department at Williams College, Stewart Johnson, one of the professors in the audience, got intrigued. The circular path is so long that it can hardly be the fastest, he figured. So what path is the fastest?

Johnson ran a simulation on his computer, tweaking the circular path in tiny ways to make it shorter and faster, until no more tweaks could improve it. The result was surprisingly close to a circle, both in its shape and its speed: It swung nearly as wide and was only 6 percent faster than Carozza’s circle.

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“This cries out for an empirical test,” Winston says. “It would be easy to do. If it holds up, God, that goes in the New York Times sports section.”