July 31, 2007
The idea of broadcasting my every emotion and/or action isn’t particularly appealing, and I’m not too keen on hearing the same from everyone else. Nevertheless, I love Twitter. Why?
It’s all about the links. People (usually) don’t twitter links unless they’re worth reading, so it makes for great reading on a pretty frequent basis. It’s great for filling those odd little five minute gaps in the day.
July 27, 2007
July 27, 2007
Good times in science land! Make magazine did an article about jam jar jets — basically a simple pulse jet in a jar (technically, a Reynst combustor). But, I don’t have a copy of Make, so I did a little reading at pulse-jets.com and set out to build one from odds and ends in the recycling bin and a bottle of isopropyl alcohol.
The first few attempts were failures. I used empty aluminum cans, which are easy to work with (cut apart, join together, punch holes in, etc.), but apparently don’t have enough internal volume or geometry to sustain a puttering reaction. Nevertheless, I scared the cats with a few good shrieks and bangs, and the good news about cans is that if you get a bang instead of a whoosh, there’s no glass shrapnel.
If someone has built a pop can jet, I’m curious to see how it was done!
Anyhow, I didn’t have a jam jar, but I did have a medium sized mason jar. Punching a one inch hole in the lid, and suspending a few inches of similarly sized pipe inside did the trick. I get about four seconds of “wuga-wuga-wuga” pulse jet action before it burns out. It sounds like a busted subwoofer, and it’s pretty sweet to see the blue flames dancing around inside at night. I’m sure I’ll get longer runs with a fuel that isn’t watered down … but it works well enough as a party trick!
In other news, high quality ping pong balls will burn enthusiastically without leaving ashes behind. Nitrocellulose, for the win.
Here’s some videos of jam jar jets in action:
- Make Magazine Video Podcast
- A real jam jar, without the inner baffle
- A (blurry) jam jar running at night
- A quick instruction with a few short clips
Have a fun weekend.
July 24, 2007
July 24, 2007
In my spare time I’m doing a little hacking with Erlang. It’s an interesting language. I’m still warming up to functional programming, but the rest of it makes a lot of sense: immutable variables aren’t as big a headache as I expected, the message passing is easy and cheap, and light weight threading without worries is a genuine pleasure. Plus, the performance is excellent.
The reason for my interest is that in the next year or so, I have several projects that are going to bottleneck on the database. Which got me thinking about caching, synchronization, and distributing data across multiple servers. The popular solution is to use memcached, slice up the database, and write a custom layer for managing the cache and database. It’s a non-trivial task, and there are two problems that get solved over and over, both have to do with synchronization:
- Cache synchronization requirements are variable. Some things needs to be updated in real time (like shopping carts), some can be loose by a few minutes (e-mail), and some can wait around for hours or days (aggregate statistics, relatively static content).
- Server-to-server synchronization of cached data is not variable. It doesn’t have to be instant, but it needs to be predictable.
All of this has to happen while serving thousands of requests per second, and the whole ball of wax needs to have tight error and exception handling. So, as a mere Erlang noob, the hype sounds like a good fit. 😉
Regardless — I’m sure there are other people working to solve the caching problem, and I’d love to hear their thoughts.
July 24, 2007
I’m about as excited as I can get — the doc says we’ll have a new family member on February 29th, 2008.
We had our first ultrasound last week. It was really neat. I’m really impressed with how precise those machines are — our little blob was a little more than a centimeter long, but we could see and hear a beating heart.
It’s about the most amazing thing thing I’ve ever seen.