Thursday, December 11, 2008

How Do You SolveRepresent A Problem Like Mariaechanics?

First, this. (Explanation)

It would be cool to make something like that, but more general. A wider scope of problems, more construction elements, more universal attachments, etc.

The standard method of genetic programming is to represent your algorithm/whatever as a tree. The leaves are data and the nodes are operations that the "universe" supports. Then two parents producing a child via "sex" is just trading subbranches. Mutation is random changes.

That works for a linear sequence of steps because there's a standard way to traverse a tree. The question is, how do you represent a machine in a tree? It's (usually) not a linear thing.

Take a wheel and a stick. They are two leaves, I guess. The node is the operator "attach"? But where? I need to know where on the stick AND where on the wheel. And if the connection is rigid, floppy, powered or what. Where is all that knowledge stored? How can I "break out" each of those things to allow them to mutate separately? Also, you can't have a whole-organism coordinate system, for instance, because a single mutation messes it all up.

Another idea is to use an algorithm to build the machine and represent the algorithm as a tree. But what's the advantage of that? I didn't realize until this morning: This is exactly what embryology is. A machine isn't a linear object, but constructing a machine is a linear process.

So to attach a wheel and a stick, I'd have an embryology something like this:

1) Place stick
2) Locate end of stick
3) Locate center of wheel
4) Attach

Or maybe:

1) Place stick
2) Advertises marker at X
3) Locate marker
4) Locate center of wheel
5) Attach

The marker system would be key. If there's more than one stick in the structure, "locate end of stick" is ambiguous. Whereas if the stick knows that it is, say, the left shin, it can hang out cards saying "I'M THE LEFT SHIN" and "HERE IS MY LOWER EXTREMITY" and the wheel can look for that.

Could one of my graduate students get on this and give me credit so I become rich and famous but don't have to stop the N projects I'm working on to get it done? Kthx!

Monday, December 8, 2008

Invention Idea #3/Story Idea #1

It's the future. Computers are unimaginably fast. Like, 8th generation Pentium fast! We want to recreate an historical figure, let's say da Vinci. All we have are the collected works.

Step 1: Recreate da Vinci's environment as closely as possible as a computer simulation.
Step 2: Assign a good guess as to what da Vinci's genes would have been.
Step 3: Simulate his life.
Step 4: Compare the output of his simulated life with his real output.
Step 5: Mutate the DNA, keeping any improvements.
Step 6: Until simulation is "close enough", goto 3.
Step 7: Instantiate DNA as a real human.

If the environment were perfect, we could get arbitrarily close to the real da Vinci. And if we had even faster computers, we could get arbitrarily close to a perfect simulation of the environment (which I leave as an exercise for the reader).

I'm going to waive the ethical considerations of steps 3 and 7 in favor of linking here.

Wednesday, December 3, 2008


  • The biggest difficulty in making something like a Stirling engine without access to a machine shop is how to make the power piston. The piston has to be precisely sized to fit inside the cylinder. However, via a YouTube video, I have discovered that it is possible to use a pair of PVC pipes to get the same effect. I made one and under breath power it worked so well it nearly knocked my teeth out. I haven't done any real testing yet, so I don't have all the construction details worked out, but basically you just get two sizes that differ by 1/4" and sand down the smaller until it fits in the larger.

  • The way I'm going to test the piston is to build another Stirling. Need a bigger displacement chamber for a piston this big. Should be metal, not too thick-walled, largish, easy to make air-tight. A paint can would be perfect, except you don't want to combined leftover fumes and high heat. Turns out Lowe's sells empty paint cans! Quart- and pint-sized. That means you can even remove the lid to work on the innards and then reseal it.

  • What with one thing and another, the flywheel on the new engine has to be mounted differently. I need a whole crankshaft dealie (which is something else it would be easier to make with a machine shop). Once I realized this, I realized I'd also need some kind of bearing. Idly reading something completely unrelated, I came across a mention of "skate bearings". I was thinking inline skates, but skateboards have the same thing. They are only like $1 each! And I even had an unused skateboard at home, from which I harvested 8 of them. ID ~8mm, OD ~22mm. Cute as a bug's bearing.

  • I've had these drawing pencils for a while now. The leads are 2H, HB, 2B and then some high B one, I dunno what. The problem is you have to keep sharpening them like every 15 minutes. The other day I realized this is already a solved problem: mechanical pencils. The only question was, do they sell mechanical pencil leads in hardnesses other than HB? Answer: Yes. So now I have 3 mechanical pencils, each with a different lead. Makes drawing so much less of a hassle. Can't shade with the side of the lead, of course, but I never did that anyway.

  • I'm not going to meet my Xmas diet goal. Scale is still going down, but too slowly to make it in time. Maybe I should aim for the secondary goal (an additional 10 lbs) at the 2 year mark (March?).

Monday, December 1, 2008

Invention Idea #2

Red increases the pulse and heart rate, and raises your blood pressure. It increases the appetite by increasing your metabolism, which is why red is such a popular color in restaurants.
("color red metabolism" gets hits mainly for People Magazine-level science info, so I don't know how well-established or bunked this is.)

The office across the hall from me just got "natural sunshine" fluorescent bulbs put in. They are much whiter than the regular bulbs, which are reddish-orange. It is causing me to wonder what effect constant immersion in red light is having on office workers. Obesity? Or is the above effect only a differential one? Has this even been studied?

Anyway, my invention: blue-tinted "diet" sunglasses.