Archive for December, 2009

Friday, December 25th, 2009

The Physics of Santa

Hands down, the stupidest Science Friday segment evar. I want my 11 minutes back. -m

Monday, December 21st, 2009

Failure as the secret to success

Excellent article in Wired, perhaps a good explanation of my career. :-)

Dunbar observed that the skeptical (and sometimes heated) questions asked during a group session frequently triggered breakthroughs, as the scientists were forced to reconsider data they’d previously ignored.

Which sounds like a fairly typical spec review at Mark Logic. Hint: we’re hiring–email me.

-m

Friday, December 18th, 2009

Mark Logic Careers

Check out the updated careers page, including a quote from YT. If you’re looking for an amazing place to work, get in touch with me. In particular I’m looking for top-notch JavaScript/FE/UI people. -m

Friday, December 18th, 2009

Taste Your Beer

I just ordered a beer appreciation kit from tasteyourbeer.com. I’m all for less swilling, more appreciating. This one includes little vials of 13 different kinds of hops to compare. Train your palate, but be warned: once you start down this road, forever will it dominate your soul. You’ll be picking out different flavors in everything you eat or drink, and some things you don’t (like toothpaste). -m

Thursday, December 17th, 2009

Steorn Orbo on display: analysis

So Steorn’s Orbo technology is on display in Dublin. They have multiple live video streams, but at the #3 view at this hour shows “Offline” and “The channel owner has prohibited viewing from this web page”. Public viewing hours run from 10a to 7p six days a week.

What is it? There’s a detailed exploded diagram (PDF) of the display model on their site. It shows a rotor assembly with three main rings. The bottom two each have 8 magnets mounted in pairs at 90 degree intervals, and the skinnier top ring has only four magnets in the same alignment. The orientation of the magnets isn’t shown. The rotor assembly spins inside a frame with four pairs of toroidal coils which line up with the bottom two rings. A separate pair of “pick-up coils” align with the top ring. No wiring diagram is included. Based on the term “pick-up coil” the top assembly looks like a generator. Spinning magnets past a pick-up coil would produce AC, so the rectifiers shown below turn the AC into bumpy DC. Meanwhile, energy flows into the system through the remaining coils.

Oh, and the “Battery D-Size”. They claim it is only being used for temporary storage, to smooth out the flow of energy, and that the device is producing three times the energy it is taking in. It goes without saying that choosing to include a battery in a display model is a terrible choice for someone trying to convince a skeptical public that the device is more than a funny-looking motor.

From pictures I’ve seen, the battery doesn’t look off-the-shelf. It’s probably a high-density lithium-ion unit with capacity similar to a D cell, maybe 12 Amp hours @ 3 volts. That’s 36 watt hours. The rotor assembly itself uses low-resistance bearings and has an overall smooth shape for low wind resistance, so the amount of energy needed to keep it turning is probably quite small. Let’s say 50 mW. Given those figures, the device could run continuously for 30 days without needing to generate one scrap of energy, even discounting the possibility of clandestine midnight battery changes and the like.

The way the system is set up, it’s difficult to establish a reliable measurement. What if you hooked up a meter to the circuit with the battery in it–which way would current be flowing?

Turns out that’s a difficult question. The current flow varies over time, which introduces all kinds of measurement difficulties. A few paragraphs back, we did a simple DC power computation with volts times amps. In AC circuits, its more complicated–the addition of inductance or capacitance to a circuit adds an element of temporary energy storage which causes the two to become out of sync, so a simple scalar calculation isn’t possible. You get in the realm of imaginary numbers and a mathematical construct called a phasor, which you draw as a simple 2d diagram. For non-sinusoidal currents, including that bumpy DC from a rectifier, the math gets even more hairy.

Is it really this hard? Yep. I wrote earlier comparing the situation to the three-body problem, most often applied to gravitaional systems, but EM analysis is even harder. Take into account magnetic fields, the interchange of electric current and magnetic fields, back-emf, and Lorentz forces operating at right angles instead of attraction along a straight line. It all gets fearsomely complicated, well past the “vector calculus just for fun” level I’m at these days.

What they’ve now publicly shown seems to be enough for a competent person to duplicate, figuring out which of the few possible permutations of electrical connections make sense. If the claims turn out to be true, expect to see independent validations springing up. But it’s not easy, so expect this interesting situation to continue to unfold over (at least) several months. If I were Steorn and wanted to speed the process up, I would ditch the battery and take steps to make it easier, not harder, to validate the demonstration.

Disclaimer: I am a member of “the 300”, and have access to the SKDB. I haven’t paid anything to nor been paid from Steorn. Information in this posting comes from only public sources. -m

Update: The official video here clearly shows the battery with the markings NiMH and 10000, which is the capacity in mAH. So my capacity estimate above was a little high, though still a good guess if it was a lithium ion cell.

But the Nickel Metal Hydride battery raises other issues: NiMH batteries are very sensitive to overcharging, which should happen if the device is dumping continuous energy into it. At best this means that the battery’s capacity will get quickly diminished, reducing effectiveness as an energy buffer (and at worst, it means boom).

Friday, December 11th, 2009

Tinderbox 5 is out

At first glance, this seems to be the Snow Leopard of Tinderbox releases–lots of behind-the-scenes technology updates and largely the same core features. If you’re looking for a way to get more organized, it’s worth a look. Link. -m

Thursday, December 10th, 2009

500th Post

Celebrating 500 posts since I went to WordPress in May 2006. Prior to that, an additional 730 posts as I floated through a typical evolution of blogging platforms:

  • Easy start: blogger (299 posts in 24 months)
  • Succumbing to the desire to roll your own (259 posts in 12 months)
  • Realizing that rolling your own is too difficult: Pyblosxom (172 posts in 12 months)
  • Moving to a mature platform you don’t need to worry about much: WordPress (500 posts in 42+ months)

-m