Technical Difficulties from on Top of the Mountain
2006-10-26
  Deep science
Most people live their lives day in and day out not worrying in the least about grain boundaries.

Sure, the spark plug wires in your car might wear out and have to be replaced (how can a wire wear out?), but for the most part you just figure that all that metal around you is just a bunch of atoms hanging out, mostly holding their shape (steel & aluminum), or pushing electricity around for you (copper, silver, aluminum, tungsten). Well sometimes what you don't know can reach up and bite you when you least expect it, so a little material science might be helpful.

So everyone's seen pictures of atoms all lined up in a row, which is how solids are organized. Sort of. As anybody who's ever broken open a rock, or chunk of aluminum or other metals knows, the surface you get isn't this perfect sheared face. Its chunky. That's because when something starts solidifying, it starts solidifying in multiple places and all these little crystals grow until they bump into each other. Each of these bits are called a grain, and the point where they meet is called the grain boundary.

If you're in to material science, than these boundaries hold all kind of secrets that scientists spend years glued to an electron microscope just to figure out. But that's not where we're going. The boundaries also present a problem to would be travellers trying to move around in there. I'm talking about electrons, trying to move through a piece of wire.

An electron trying to cross that boundary sees a gap. And that makes life a little difficult. In return for getting beat up crossing over, the electron punches back at the metal as it goes by. Just one electron doing that doesn't do much, as electrons are pretty small, but 1 amp of current going through a wire represents 6.25 quintillion electrons (6.25 X 10 to the 18th), so it can start to add up over time. This explains the problem the folks back in the 1970s were having with DIY solar power projects.

Back then, before computers were common (I know, hard to imagine), the fast switching power transistors that the computer uses in its power supply weren't very common either. That meant it wasn't very easy, inexpensive, or efficient to turn DC voltages from solar panels into 110 V AC that all your appliances know and love. Some people went out and stocked up on 12V RV appliances, but others got more creative and pretty much tried every single device out there to see how it would work on DC power somewhere between 90 and 120V.

Light bulbs (being just a piece of wire that heats up), would seem a natural. That is until you learn the physics:

Incandescent lamps can operate on DC voltages. However, two phenomena must be considered.

The first is the fact that light output of an incandescent lamp follows the Stefan-Boltzman Law which implies that light output is proportional to the fourth power of the operating voltage. Thus a 10% decrease in voltage results in a 34% reduction in light output. (not that great when your batteries are a little run down)

The second phenomena is metallurgical in nature. The incandescent tungsten filament in a lamp undergoes a grain boundary modification on DC operation. This results in a reduced life for some lamps when operated on DC. However this effect is very temperature sensitive, so normal lamps operating over 2800°K show little problem, whereas long-life lamps and very low-wattage types (such as night lights) operate at reduced filament temperatures (below 2700°K) which make them susceptible to this effect.

From: the new solar electric home

Curses, foiled by that grain boundary again. Luckily we now have IGBTs and MOSFETs coming out our ears and can take a DC power supply and chop its power into little tiny pulses which we push through a transformer to turn into anything from 110V AC to 480V 3&Phi,; so our lightbulbs will stay happy. Except of course that they're being replaced by CFL lights which are way more efficient, have they're own little inverter stuck in the base, and as thus, ironically, are perfectly happy running on DC.
 
2006-10-08
  Burning dead trees
Its the edge of winter here again in the mountains, and that means the pellet stove is up and fired and I'm out scouting around for cheap sources of carbon and hydrogen. Actually this last week its been pretty warm which was nice because a few weeks back in what should have been the beginning of fall, it was darn cold. So cold in fact that I managed to burn nine bags of pellets to keep the wife from realizing/remembering how bad its going to be around February.

I did manage to pile very close to a ton of pellets in my Highlander for the week when Home Depot had lost its mind and was selling bags for $3.11. Unfortunately, by the time they had restocked, they had also come to their senses and raised the price to $4.39. Still cheaper than Walmart which has turned their entire garden center into a pellet storage facility where those pellets may live most of the winter if the price doesn't come down from $4.99. Still, I'm pondering how to keep my stock up for the winter. Based on last year's count, I need somewhere between three and four tons of pellets. Right now I'm sitting at about two (minus what's burning as we speak), so I'm going to need more, but I'd like to still be able to move around in the garage, and I had a vision of a large stack of pellets, sitting on the concrete next to the pit, exerting enough force to chip off a piece of the retaining wall and slide down into my underground pump room.

The second phase of my heating strategy is the same material, but in a rougher form: raw chunks of wood stuff. We have quite a pile of purchased wood sitting out back, but I like to start off the evening with sloppy pine mostly because I usually get it free or near free. The good stuff is $200 a cord, so its questionable how much we're saving burning that instead of other alternatives. Right around February we'll have every heat source possible running at 100% at the same time, just to keep us out of the ice age, so we need some of the good wood, but before then I'd rather be saving money (and spending it on ebay instead of on heating). So I try and get whatever pine I can. Last year we were finishing up a multi-year pile of dead trees delivered to our yard courtisy of a good friend, but this year I was wondering what I was going to do without much plan to resolve the situation on my own. Luckily God pitties me, and he knocked over a 80' tree right into a nice flat spot, and its even easy to get to with my car or truck. So over a couple of weeks, I went out and cut this enormous thing into slices 4-6 feet long and somehow managed to get each of them into the back of my dad's truck and dumped into my yard. Finally, when I though I could handle no more; he had someone else go and wipe out the last quarter in the space of an hour, so that I wouldn't worry about it any more. I also managed to get in on one week of the fire departments tree thinning and picked up a truckload of smaller stuff, but its completely green.

So starting off my log for the season:
September360
Octoberworse

 
2006-10-04
  A tale of two Dews
From season to season, it falls to my shoulders to do the grocery shopping. This usually happens during my prime thinking time: in the middle of the night. Sometimes I have a "I'm not tired" kidling with me (who is asleep by the end of our adventure), other times its just me wandering up and down the isles wondering what they were thinking when they invented strawberry and bananas shredded wheat.

One of my faults (or blessings depending on if my wife likes the selections), is that I buy things that are on sale. We currently have about 40 boxes of fruit chews in the pantry, because they were onsale, and then they were onsale more. "But they were only a $1 a box!" One area that I have a little more leaway is in my personal snacks, like my drinks.

It looked intriguing, it looked caffinated, and nobody else had been buying it, so it was cheap. In this case I have to side with the other people who weren't buying it. I can only describe it as if they took all the reject grape/cherry flavored kids cough medicine from the '80s and mixed it with Mountain Dew. Eyach. I guess somebody was buying though, cause they even came out with a sequell. Luckily these were both limited time disasters.

Cracked this case shortly after with some treppidation. Turns out this was much more on track with my tastes. I've been drinking a lot of Orange soda lately, but the hard part is in finding a mix that's properly caffinated. Sunkist has got it right, but all the other orange drinks seem to be pandering to the 8-14 year old market where it still has to pass the Mom test (well, any type of soda wouldn't have passed my mom's test, so maybe it only has to pass the mom lite test). Live wire is sort of hyped up orange soda with just a tint radiator fluid. Kind of like orange drink that's 30 years old, so the dyes have broken down and are off color, but carbonation never dies, so you drink it anyways.

So I'm liking it, but unfortunately I only have the one case of it. Not like this guy—he aparently bought every box in the store.

 
Life in the middle of nowhere, remote programming to try and support it, startups, children, and some tinkering when I get a chance.

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Blogroll
Paul Graham's Essays
You may not want to write in Lisp, but his advise on software, life and business is always worth listening to.
How to save the world
Dave Pollard working on changing the world .. one partially baked idea at a time.
SnowDeal
Eric Snowdeal IV - born 15 weeks too soon, now living a normal baby life.
Land and Hold Short
The life of a pilot.

The best of?
Jan '04
The second best villain of all times.

Feb '04
Oops I dropped by satellite.
New Jets create excitement in the air.
The audience is not listening.

Mar '04
Neat chemicals you don't want to mess with.
The Lack of Practise Effect

Apr '04
Scramjets take to the air
Doing dangerous things in the fire.
The Real Way to get a job

May '04
Checking out cool tools (with the kids)
A master geek (Ink Tank flashback)
How to play with your kids

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