Powering the World Using Natural Motion
Scientists at the University of Houston recently found that the electrical sweet spot producing the most efficient charge occurs when a piezoelectric filament is about 21 nanometers long. To put that into perspective, if you lined up 4,000 of these filaments next to each other, it would be about the width of a human hair.
Hey, it’s something from Oregon State. What can I do but link to it? I’m an alum; maybe they’ll link to be in their blogroll.
*answer to “Do you like Pauling?”
CIA Realizes It’s Been Using Black Highlighters All These Years
According to the report, sections of the documents— “almost invariably the most crucial passages”—are marred by an indelible black ink that renders the lines impossible to read, due to a top-secret highlighting policy that began at the agency’s inception in 1947.
CIA Director Porter Goss has ordered further internal investigation.
“Why did it go on for this long, and this far?” said Goss in a press conference called shortly after the report’s release. “I’m as frustrated as anyone. You can’t read a single thing that’s been highlighted. Had I been there to advise [former CIA director] Allen Dulles, I would have suggested the traditional yellow color—or pink.”
Goss added: “There was probably some really, really important information in these documents.”
Hubble Space Telescope Advent Calendar 2008
As we head into the traditional western Holiday Season, I’d like to present this Hubble Space Telescope imagery Advent Calendar. Every day, for the next 25 days, a new photo will be revealed here from the amazing Hubble Space Telescope. As I take this chance to share these images of our amazing Universe with you, I wish for a Happy Holiday to all those who will celebrate, and for Peace on Earth to everyone. – Alan (25 photos total – eventually)
[H]ere instead is a list of phrases that (at the time of this posting) turn up no hits on Google:
“ate a violin”
“driver-side bidet”
“unlike normal furries,”
“Sarah, plain and tall and a cyborg”
“people are too civil on the internet”
And some more in the comments
“differential equations saved my life” – 0 results
“chess for Wookies” – 0 results
“erotic vector calculus” – 0 hits
“Luke, I am your third grade teacher” – 0
“Search your kitchen counter, you know it to be true” > 0 results
“Buttered graphite” – 0
Are you worried about global warming? Should you be worried about global warming? Understanding the dangers posed by climate change and evaluating policies toward it require some understanding of science. How do we know the Earth is warming? What will happen when the temperature increases? What can be done to mitigate or avoid the problems? These are essentially scientific questions.
What about bird flu? MRSA? AIDS? Pandemic disease is something that can only be understood and combatted through science. Are we all going to get wiped out by some disease? What steps should we take to avoid being wiped out by disease? These are essentially scientific questions.
If you have no interest in science and being informed, then you can only blame yourself when you get conned by someone peddling antiscience, or swept up by FUD.
We can’t get good at something solely by reading about it. And we’ll never make giant leaps in any endeavor by treating it like a snack food that we munch on whenever we’re getting bored. You get good at something by doing it repeatedly. And by listening to specific criticism from people who are already good at what you do. And by a dedication to getting better, even when it’s inconvenient and may not involve a handy bulleted list.
This is precisely why teachers assign homework problems for their students to work out. You get better at physics by applying it to unknown situations and figuring out the answer. Not by having someone work multiple problems for you.
My own method when someone explains some concept to me is to try and come up with a nontrivial example and give the result, trying to explain myself, and see if I have figured out the application of the concept.
I compare/contrast this with behavior of people who say they are trying to learn (level of sincerity unknown) and who just want to be spoon-fed the answer, without knowing the path to the answer. And who often complain that it should be easier.
[A] subscription to a magazine about taekwondo will only be as useful as your decision to drag your fat ass into a dojo and start actually kicking people. Over and over. Otherwise, you’re just buying shiny paper every month.
Here we have a beautifully illustrated example of Newton’s First Law of motion involving shopping carts. Did some force push those carts out the back end of the trailer? Not at all.
Guess the movie from just one letter taken from the movie’s poster (not necessarily the first letter, or most artistically distinct letter that appears). I got five.
Over at Good Math, Bad Math, Mark has a takedown of a device purported to move directly downwind, faster than the wind. Wind-Powered Perpetual Motion (and Dave Munger thinks he’s wrong.)
Here’s the video
The objection is simple: when you are traveling at the wind speed, there is no more wind in the cart reference frame, so there’s no force. The treadmill analysis is flawed.
If you’re testing a wind powered vehicle, then in a closed, windless room, putting the vehicle on a treadmill moving at 10mph is not the same thing as putting the vehicle on a stationary surface in a 10mph wind.
By putting it on a treadmill, you haven’t recreated the real-world situation — you always have your wind, and the treadmill doesn’t remove that. You never test the condition of having the wind relative to the cart drop to zero. So while it’s not faked, it’s still a sham.
It shouldn’t be hard to engineer a device such that the wheels rotate faster than the propeller, i.e. whatever the propeller’s rotation rate is for a wind of speed X, the wheel edges move faster than X. Since the wind is always present, the cart will move forward on the treadmill moving at X. Even uphill.
My question is this: if this works, at what speed does the cart stop accelerating?
UPDATE: Or with no wind present, as in the test (On the first viewing I thought they had a fan turned on) what you’re doing is converting treadmill kinetic energy into propulsion by turning the propeller. But you don’t need to have much propulsion to move forward, even uphill. Not a valid test.
Update, Mark II. See the comments — I was viewing this from the mistaken notion that the propeller was acting as a turbine while on the ground and at low speed, which isn’t the case.
This has the implication, I think, that the cart must have enough mass to ensure that the propeller acts as a propeller. My question of what the maximum speed is still stands, because I’m sure it involves fluid mechanics and that’s not something I’ll win should I tangle with it.