Wednesday, April 8, 2009

Another black eye for CFLs

Lifetimes shorter than advertised.
Slow (minutes-long) start up times.
Environment-contaminating mercury.

Now add power consumption to the list of reasons why compact fluorescent lamps (CFLs) aren't all they cracked up to be.

This EDN article points out that CFLs have a terrible power factor, between 0.4 and 0.6. In layman's terms, this means the lamps are using 66 to 150% more energy than advertised: a 13 watt lamp may require the power company to actually pump the energy equivalent of 32.5 watts down the line to light it up.

The good news -- for you, at least -- is that you're not actually billed this larger amount. Electric meters measure "real power" -- the 13 watts put off by the bulb. The bad news -- for the utilities and the environment -- is that the electric company has to provide the "apparent power", or the equivalent of 32.5 watts.

This is still less than the 60 watts needed for an incandescent bulb, but it does eat away at the magic of CFLs.

(Apparent power is usually given in volt-amperes; this is dimensionally equivalent to a watt, but this helps us electrical geeks to distinguish when we're talking about "real" vs. "apparent" power.)

Monday, April 6, 2009

Does not compute

An article in today's AP news feed claims that 1 in 5 four year-olds are obese. Sure, obesity is a problem in our populace and it's no surprise that this is reflect in our children.

However, the definition they're using is suspect:
Children were considered obese if their body-mass index, a height-weight ratio, was in the 95th percentile or higher based on government BMI growth charts.
If they're using the 95th percentile, then only 1 in 20 (5%) of children are obese by definition.

What they really meant: "95th percentile or higher based on historical government BMI growth charts." In other words, a category which used to constitute 5% of four year-olds now represents 20% of them. Or, heck, quit with the political correctness and just set a number: obesity in four year-olds is defined as a BMI or 18 kg/m2 or higher. Save the percentiles for justifying how you decided upon using 18 as the magic number.

Sunday, April 5, 2009

Weekend chores and pranks

It was dark and snowy on Wednesday. Today, it was sunny and in the upper 60s. Such a dramatic change injects a lot of energy into people, and we were no exception.

The kid's room is now ready -- wallpapered, all electrical sockets have been childproofed, drapes are up, and all other adornments are adorned. The attachments needed to mount the used bike rack we got for my car have been obtained and the rack is successfully attached. We even cleaned up the yard a bit -- mowed the grass, ripped out a lot of blackberries, and mulched it all. I also got some mounting hardware for my traffic signal and painted it all (Ace Hardware appliance paint -- spray paint mixed with epoxy -- is excellent stuff).

I also got a small bike ride in and did a bit of swimming in Port Orchard. No distance; this was more of an acclimatization exercise -- the air may have been 68°F, but the water is still around 47°F. I can definitely feel the difference since last November. Back in November, it would take me about 3 minutes to acclimate myself to the cold; now, it's up to 8-10 minutes and the cold is still noticeable.

Anyway, while riding back from Port Orchard on my bike, I thought of an interesting prank. North Korea claims that it successfully launched the Kwangmyongsong-2 satellite, though everyone knows that it was really a failed missile test. They claim that it's orbiting every 104 minutes and broadcasting patriotic songs on 470 MHz (that's UHF TV channel 14, should you want to try picking it up on your rabbit ears). Alas, nobody has actually heard anything on this frequency.

Which got me thinking...

What would people do if I set up a transmitter on this frequency and blasted "Song of General Kim Il Sung" and "Song of General Kim Jong Il" on it, fading it in and out every 104 minutes? What kind of rationalizations would folks make? How quickly would the hoax be discovered?

On that last question: my guess is fairly quickly, but that wouldn't stop a new group of conspiracy theorists from forming their own cute new clique.