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brakelines and hexagons
Monday, September 9 2013
It's not difficult to get lost in the woods to the west of our house, since its terrain is nearly flat, and the trails (such as they are) are chaotic and visually monotonous. On occasion I've discovered myself to be walking around in circles there, unable to find a way out. This is particularly easy to do when there is no sun. This morning while I was walking the dogs through that Bermuda Triangle of a forest there was a sun, and I eventually used it to guide myself northeastward. That's a trajectory that nearly always leads to our uphill neighbors' place, which stretches for hundreds of feet along Dug Hill Road. But even before I get there, the plateau starts to fall away over the course of a number of terraces. Just that relief, and the fact that the contours associated with it run more or less southeastward, provide all the guidance I need to not get caught in an endlessly-circular trajectory.
Today I turned my attention to the Subaru's brakes, which (as you remember), failed me in the Adirondacks and which I "fixed" by plugging some of the lines so they wouldn't leak brake fluid, thereby sacrificing one of the brakes. In looking at the brakes again today, without the stress of being a hundred miles from home and needing to be able to drive the car. Looking at the rear brakes again, I realized that what I'd thought was two hydraulic hoses running to each was actually just one hose and the cable for the emergency brake. The front brakes really do have two hydraulic hoses each and evidently two cylinders each. But the two lines I'd blocked going to the back of the car must have actually been blocking fluid to both rear brakes, so I'd been driving on only two brakes, not three. It didn't take much effort to unblock the one tube going to the driver's side rear wheel, which turned out to be the topmost connector on a little junction box that is just before the perforation through the the engine compartment's rear firewall. (I'd tried blowing through that pipe up in the Adirondacks and it had seemed stopped-up, giving me information that I now interpreted to mean it went to the still-good brake.)
I also explored to Subaru to see where I might splice in a replacement brakeline. On our old 1998 Honda Civic, the brake lines ran in a conduit cage beneath the belly of the car, where they tended to rust from exposure to road salt and moisture. In this 1998 Subaru Legacy, I discovered that the brake lines had been routed entirely inside the car, where they were protected from the elements and showed no evidence of weathering. It was only where they emerged near the rear wheels beneath the car that they were exposed to conditions that caused them to corrode. After much searching and tracing both inside and outside the car, it seemed like it would be a relatively-easy job to replace the corroded section of brake line. I would just need to buy some tools and master the technique of "flaring" the end of replacement line to make junctions. Since Gretchen and I drive our cars into the ground and got rid of our old 1998 Honda Civic because of what we were told were soon-to-fail brake lines, it seems like a useful skill (and toolset) to have. So I placed an order for about $200 worth of tools and supplies.
Another project I did today was for my best regular web client. He had an idea for a project that would require a hexagonal grid overlaying satellite views of various communities. My job, then, was to find a way to plot such a grid on a Google Map. This sent me in search of a means to calculate the coordinates of a hexagon's vertices, and I found a very helpful page. Using that information, I plotted a nice hexagon on a map. Next I added a loop to plot a field of them. By changing various constants, I could plot any number of hexagons of any size starting at any midpoint on Planet Earth. The only oddity was that perfectly-good hexagons plotted near the equator tended to get tall and skinny when they were plotted with the same formula near the poles. So I added a distortion factor (v in the code below) that can be changed depending on the latitude of the area being overlain with the grid. Here's the relevant code that I used for the Google Maps API version 3:
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http://asecular.com/blog.php?130909 feedback
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