Alkahest my heroes have always died at the end

August 22, 2006

carrier thermidistat design – let’s put it in the category of needs to be fixed

Filed under: Personal,Technical — cec @ 10:56 pm

Back when I was a grad student and just about to finish up, the school of engineering turned a class of 60 freshman over to me to teach intro to numerical methods for engineers. I tried to liven things up by emailing the occassional engineering funny to my students who even reciprocated. The following is a brief excerpt from an engineer identification test that was sent to me by a student.

To the engineer, all matter in the universe can be placed into
one of two categories: (1) things that need to be fixed, and (2)
things that will need to be fixed after you’ve had a few
minutes to play with them. Engineers like to solve problems.
If there are no problems handily available, they will create
their own problems. Normal people don’t understand this concept;
they believe that if it ain’t broke, don’t fix it. Engineers
believe that if it ain’t broke, it doesn’t have enough features
yet.

That brings me to an issue I’ve been having. A couple of years ago, we put in a new heatpump with humidifier, it came with a new thermidistat which didn’t seem to work too well. When the A/C cut on, the temperature on the thermostat rose several degrees, at one point jumping from 78 to 86, while the temperature in the area remained constant. I realized that the problem was the relays. The A/C kicks on, the relays heat up and the thermister gets hot. We called the installer, got a new thermidistat. It did the same thing.

We discovered that we could use a small fan to blow air on the thermidistat. That worked well, but was irritating. So we moved the thermostat to a place with more airflow. Same problem, but to a lesser degree – the A/C cuts on and the system jumps from 78 to 79. Of course, to get it back down to where it would shut off, the thermostat ran the A/C until the house had cooled to about 75. Bah.

Finally, this weekend, I opened up the thermostat and added some redneck engineering to it. I insulated the relays using cotton balls and tape. So far so good. If this didn’t work, the next step was to just buy a different model of thermidistat. But let’s face it, do-it-yourself insulation is more fun. So, for the record, we can officially put the design of the carrier thermidistat in the category of things that need to be fixed.

UPDATE: let’s spell carrier correctly, shall we? 

racial profiling for terrorism

Filed under: Security,Social — cec @ 6:53 pm

I’ve heard and read a number of people saying “political correctness be damned, we should use racial profiling to identify terrorists.” The problem I’ve always had with this is that it makes no sense. Try the following test, identify the terrorist:

  1. young muslim male
  2. young muslim female
  3. asian male or female
  4. caucasian male or female
  5. black male or female
  6. hispanic male or female

If you said that 1 and 2 have been terrorists and therefore we should profile them, you are partially right. However, what about all of the asian terrorists (e.g. Fillipinos)? Caucasians? Hmm, the IRA, David Koresh, Timmothy McVeigh, etc. As near as I can guess, the only racial groups that shouldn’t be profiled would be blacks and hispanics. This can’t work.

NBC Nightly News just had an interesting story on behavioral profiling being done at the airport in Orlando. Essentially, the police have been trained to look for suspicious behaviors, not suspicious racial characteristics. This is a much sane approach from the security perspective and can be much more effective with a lower rate of false positives.

POSTSCRIPT: from the security standpoint, any action needs to be considered from the risk mitigation standpoint. What’s the risk? What is the rate of false positives (FP) of the action? What are the costs of the FP? What is the rate of false negatives (FN)? Costs of the FN? etc, etc. Racial profiling fails under a risk mitigation analysis. Behavioral profiling may make sense.

a small request of the NC-DOT

Filed under: Personal — cec @ 8:55 am

I have a small request to make of the NC-DOT, if there are accidents on the interstate at I-40 and I-540 which backs traffic up 10 miles to NC-751, can we please, please make use of the expensive electronic information signs on the interstate to warn people?  There’s a difference between a small traffic slowdown that you will soon get past and one that means you’ll be driving 5-10 miles at an average speed of 10-15 mph.

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