Tuesday, August 24, 2010

blogger question

Does anyone know if there is a way to get the "summary" field in the atom feed from a blogger blog to include thumbnails of the images in the blog?

I recognize that this would probably require some coding on Google's part, but it doesn't seem like anything that's beyond them, and it would be a pretty cool feature/option.

Saturday, August 21, 2010

Hyperbolic Paraboloid Buildings

Ever since I first stumbled upon them in "A Visual Dictionary of Architecture" I've been fascinated with the concept of hyperbolic paraboloid buildings.

Essentially a hyperbolic paraboloid is a structure which, in some frame, is described by the equation

z=x*y

If you slice it along constant z you get

1~ x*y or y~1/x or x~1/y

If you slice it along a line y=k*x you get

z=k*x*x or z=k*x2

But the part that makes it useful as a surface for buildings is that if you slice it along constant x or constant y you get

z~x or z~y

in other words, a straight line.

For this reason, it is called a "ruled surface", and a framework for it can be made entirely out of straight beams, as in the pictures from this site

http://www.savetrees.org/Hyperbolic%20Paraboloid%20roof%20shelter.htm



One problem with such a surface is that, while it is easy to construct the frame out of straight beams (and the resulting structure is known for its strength), constructing the roof to fit into the frame is non-trivial, especially if the surface must be hard.

It is *possible* to construct something that mostly fits snugly over it by cutting pieces out of a cloth tarp (as shown in the above link), but any patch of the true surface of the object is curved (as well as any line which is not constant in either x or y)

One solution might be a "concrete tent" similar to what is proposed in this article
http://www.wired.com/science/discoveries/news/2005/03/66872 (start with a "tarp with sections cut out" and brush wet concrete over it. Then let the structure harden)

Another alternative might be to layer a fine mesh of straight wires along constant x and constant y, and take some goopy filler material, such as plaster, and brush it over the wire mesh. I wonder if something like this is how they make permanent buildings with hyperbolic paraboloid roofs. Some of the images of such structures certainly look like a wet material was painted on top of a mesh and then allowed to dry, although larger hyperbolic paraboloid structures, such as the Catholic Cathedral on Gough Street in San Francisco, are often clearly made from piecewise surfaces (float or otherwise). I think to have a piecewise surface of flat segments perfectly conform to a frame of straight segments in such a roof, the segments have to be triangles (and highly irregular ones at that!)

Thursday, August 19, 2010

This time last year



This time last year, the mountains around Los Angeles were on fire. At 15 miles away, you could see the flames sometimes in broad daylight. And at night a 30 degree arc of the skyline would glow red. One of my favorite nights in Los Angeles was the time I sat out with a bottle of cheap red wine just watching as the sky burned around me.

Side note : the way I found the time-lapse video of the high voltage tower construction
http://mikeschuresko.blogspot.com/2010/01/really-cool-time-lapse-video.html that I posted around this time last year was by looking for videos of the Station Fire, and finding this one
http://www.youtube.com/watch?feature=iv&v=jR_3N7nVPw8 by the same guy. I like the music in his videos, but I feel that they don't adequately capture the scale of the fires or how the sky turned red from the other side of the city or how everything smelled like a smoky oak campfire.

Friday, August 13, 2010

Planning

On my bike ride to work, from Mountain View to Cupertino, I usually start on the Stevens Creek Trail, and I can take either one of two routes after crossing El Camino Real.

One of them takes me through the red circled region on the map posted below, while the other takes me through the blue.



I will call the blue region (the "circle" around it isn't closed since the region extends off the map) "ecocity Sunnyvale". It has actual bike lanes, streets connect, so that things a close distance apart can actually be walked or biked to, and the area seems to be fairly mixed-use (schools, businesses, etc) for a residential / sprawling ranch houses area.

The red region, while superficially similar by the map, is an entirely different beast. The dashed green line going through it on the bicycle map isn't so much a bike path, as it is an unmarked route through a maze of suburban cul-de-sacs. Having successfully laid out the streets in such a way as to prevent cars from cutting through this neighborhood, whoever designed this area also managed to prevent cyclists and pedestrians from taking any sort of sensible straight cut-across, while simultaneously zoning the entire region purely residential.