Various computer entropy

  1. How come every few days I wake up to find my screen non-blanked, and have to do this:
      pmset -g assertions | grep PreventUserIdleDisplaySleep
    usually followed by this:
      sudo killall -HUP powerd

  2. How come this doesn't work any more? It now seems to behave as if the lock timeout is some random amount of time greater than 30 minutes but certainly less than 12 hours:
      defaults write askForPassword 1
      defaults write askForPasswordDelay -float 43200
    This is complicated by the fact that the System Preferences UI doesn't let you choose a number greater than 4 hours. However it's not merely maxing out there because I've seen it go into password-mode in as little as 30 minutes.

  3. How come NetNewsWire 3.3.2 now periodically gets stuck forever in "Refreshing..." (usually in "Processing downloaded article IDs"). Is NetNewsWire effectively orphaned now? Is there a better Mac desktop feed reader that syncs with Google Reader?

Previously, previously.

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Conway's Rorschach Mask: Assume a Spherical Bunny.

Conway's Game of Life for Curved Surfaces

Non-Euclidean Geometry

Looking at the above equations, the only place where geometry comes into the picture is in the computation of the M and N fields. So it seems reasonable that if we could define the neighborhoods in some more generic way, then we could obtain a generalization of the above equations. Indeed, a similar idea was proposed in Rafler's original work to extend SmoothLife to spherical domains; but why should we stop there? [...]

But this isn't the only way we could define this distance. While the above formula is pretty easy to calculate, it by far not the only way such a distance could be defined. Another method is that we can formulate the path length variationally. That is we describe the distance between points p and q as a type of optimization problem; that is it is the arc length of the shortest path connecting the two points.

From the SmoothLife guy.

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Seeking quiet electric motor

Dear Lazyweb,

My curtain automation is very loud. The idea was for it to open the curtains in the morning as a gentle reminder that the Sun exists and I should get out of bed, but the reality is that the noise rather than the light wakes me up most days.

As far as I can tell, most of the noise is coming from the motor itself rather than from the gearing or the curtain track, so I'd like to replace the motor with one that is quieter. It couldn't hurt to have one that was more powerful as well, since this one is clearly straining a bit toward the end of the cycle.

What am I looking for? I don't know how to shop for these things or how any of this is specified.

The existing motor is about 1" in diameter, and the replacement would need to be very close to the same size. You can see it in the photos. It's 12VDC now but with a little hassle I could run it on something else.

I may try building a padded box over the whole contraption, but that doesn't strike me as a very promising approach.


Victory! My curtain is now insanely quiet. Thanks to several of the suggestions here, it was a multi-pronged approach that did not involve replacing the motor at all.

  1. I opened up the box housing the motor and gearbox (pictured above) and packed it full of clay (Sculpey).

  2. I built a cardboard box to hang on the wall around that contraption, with just two holes at the top for the pulley ropes to penetrate. I lined the inside of it with PC-case sound-foam, and lined the outside with two layers of 1/8" mass-loaded vinyl. At that point, the motor was almost inaudible. The box isn't pretty, but it's hidden behind the curtain, so it's invisible.

  3. I then moved on to the next-noisiest thing, and lubed up the curtain track and its wheels with aerosol Tri-Flow.

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