Tuesday, September 29, 2009

Recap Number One

I'm going to be rather busy for a while, so instead of creating new content for this blog, here's a selection of some of the better past entries for your recycled viewing pleasure. Save trees, read old posts.
  1. "How to Buy an Airline Ticket"
    The must-read post that could save you trillions! Or, more likely, teach you something about differential pricing schemes.

    Computational biology like you've never seen it before.

  3. "On Engineering Blogs and Bluffing"
    This is the post that really got the ball rolling, back in the day.

  4. "Microsoft iPod"
    Color images make their debut on this blog (not counting images of food). This post also features a viral video about branding.

  5. "GUID Socks"
    The greatest single idea since dental floss. Coming soon to a store near you.

  6. "Disc Golf"
    Everyone should play disc golf.

  7. "Personal Satellites"
    Anyone want to team up to build one of these?

Sunday, September 27, 2009


Update: The university has a pretty comprehensive page about this issue.

I like the health services provided by the University of Waterloo. They've been extremely helpful to me in the past and I'm glad that they're taking steps to reduce the chance of a flu outbreak.

Nonetheless (and there had to be a nonetheless), it's hard to image swine flu (H1N1) necessitating all the measures that have been put in place. There are signs on the central Health Services building instructing patrons to enter by the back if they have any flu symptoms, including coughing. There have been emails sent to students asking them to self-quarantine themselves if they have any symptoms. Most surprisingly, influenza has been made an exception to the university policy of requiring verification for illness when missing examinations.

This means that if you develop a cough during exams, you're supposed to call Health Services so that they can tell you not to visit them and instead to quarantine yourself in your room and write the exam later. The potential to abuse this system is obvious and I think it's questionable whether students who have early flu symptoms really will self-diagnose and stay at home. Still, preventing a pandemic is clearly more important than avoiding an honor system for exam scheduling, so I can understand the university's decision.

The quarantine signs are still ominous.

Wednesday, September 23, 2009

You Don't Know Slow

Driving below the posted speed limit is not slow. The pace of the "Fellowship of the Ring" book was not slow. A snail dragging a brick is not slow.

Then what is slow, you ask, if not these things? A computer program to simulate all possible recombinations of a couple strands of DNA, is what. Specifically, the current implementation of the Recombinatron project I've previously posted about.

We've known for a while that the program was slow. There was talk of "factorial run-time" and "exponential growth" but we didn't really pay that much attention to these things. Time's too short to waste it figuring out Big O notation when you could instead just run the program.

On a computer with 12 GB of memory.

And wait eight hours as the program stalls on step 4 of 255.




It turns out the program's pretty slow. Not "man, FancyApp 2.0 sure is slow" slow, but "man, this won't even be halfway done before the sun dies" slow.

Monday, September 21, 2009


This is depressing for a few reasons:
  1. This is a fairly accurate copy of part of my Signals and Systems work.
  2. All the comments were written by me. Talking to myself. On paper.
  3. The math in it is pretty easy.
Having said that, signals is a good time. Go Ed (Jernigan), go.

Wednesday, September 2, 2009

Playing with Transformers

I'm on vacation now. Naturally, this means that I no longer have to program, or do circuits labs, or build cardboard bridges. Equally naturally, I'm hoping to get some programming for iGEM done and maybe start a woodworking project and play with electrical stuff...

It was while playing with electrical stuff recently that I found out just how little I actually recalled from my class in Electricity, Magnetism, and Optics (EMO). I mean really, how hard can it be to hook up a fluorescent light? (Answer: if you don't have the ballast, good luck with that.) Even making LED circuits involves a surprising amount of calculation which, engineering student that I am, I immediately delegated to an online designer.

My dad also keeps a box full of random parts salvaged from various radios and computers. This is pretty cool. The box had a few transformers in it, so we decided to test one by hooking a battery up to one end and a multimeter to the output wires to see what we obtained as output voltage. At this point, the electrical engineers reading this (and who have seen the image at the top of this post) can probably guess what happened.

Nothing happened. At least not at first: we had connected the battery, then I connected the multimeter probes, holding them to the output wires of the transformer with my fingers. My dad then removed the battery, and I jumped out of my skin. Fortunately, even with the transformer, the shock from the AA batery was far from deadly.

So what happened here? Why, and this is becoming something of a theme on this blog, am I such an idiot?

The thing is, transformers are meant to be used with alternating current (AC) and not direct current. The reason for this is pretty simple: the transformer consists of two coils of wires which are, as wikipedia says, inductively coupled. And, as I should have known, the induced voltage in an inductor is proportional to the rate of change of the magnetic flux through it. With the battery attached, there was no change in current, therefore no change in magnetic flux and no electrocution. Remove the battery, however, and things do change.

There's nothing quite like a light shocking to act as a remedial science lesson.