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August 26, 2007

Fibonacci's Pine Cone

Yesterday some of us at work were walking back from lunch and I mentioned there were rumors of a new iPod. It was going to be as thin as a nano, but the size of a squat 5G. Already people were saying how ugly it was and part of that is because it isn't a golden rectangle where the ratio of the long side to the short side is 1.618:1.

Well that got Paul talking about Fibonacci numbers and how the numbers show up in nature all over the place. Fibonacci's numbers are easy to calculate: it is just a series of numbers where the next number is the sum of the previous two: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, etc. The numbers get big pretty quickly. So he started talking about pine cones and how you can see spiral patterns in the scales if you look at the big end of a pine cone. Further he said that if you follow the spirals one way you will get 8 arms of the spiral, but if you go the other you will get 13. I didn't see how you could have different numbers of spirals on the same pine cone.

By this time we were at the Capitol, so he went and looked for a pine cone under one of the trees on Capitol Square. He brought back and started showing me how to count the arms, and sure enough there they were.

He said that all kinds of things from the heads of sunflowers to the spikes on a pineapple follow similar patterns and the numbers are usually Fibonacci numbers. I found a great site with tons of examples (and some examples of plants that don't participate in Fibonacci's conspiracy). That's also where I got the pictures of pine cones.

August 23, 2007

New Web Host

I am still the webmaster for the employees' association at work. Currently their website is hosted by hostway.com. They charge $13.95 per month for hosting the website and $19 per year for registering the domain name. In reading up on the subject some people say that you should not have the same company host the site and register the domain. I found an inexpensive and well regarded registrar called namecheap.com (GoDaddy is a more famous one; like most of these companies they also host websites) that charges $8.88 per year. I also found a well regarded web hosting company called A Small Orange that charges only $25 per year for their smallest web hosting package (75 MB of storage space 3 GB per month of traffic). It turns out that ASO's servers are located in Atlanta, so that's even better.

So far, so good. With only a month to go before my Hostway account renews itself, I signed up for accounts on both NameCheap and ASO. While I was at it, I bought another domain since we were using a gdotea.com address and, being a nonprofit organization, I thought we should have gdotea.org so that it would forward anyone who typed that to the .com site. I was reducing the web expense from $186/yr to $36/yr, so I thought another $8.88 wouldn't hurt.

They don't make it easy to switch all of this around. Even though users will still be going to www.gdotea.com and the web pages will look exactly the same, the web files will be stored on a different computer on the internet owned by a different company. This is done through a DNS system that takes a URL that a user types in and then puts them in touch with the appropriate computer that has a numerical address of 4 numbers separated by dots ( They don't make it easy because they don't want me to be able to change cnn.com to point at some bogus website.

The current company has no incentive to let you switch since they want to continue to charge you for this service. Hostway supposedly makes this pretty easy except that I found out today that I do not have permission to do that. Instead it was still in the name of the original webmaster who had set all of this up (and fortunately still works here), even though I actually paid to renew the domain last year. Once I get that information I will be able to use the EPP code which will authorize namecheap to execute the transfer. Without the code you can't do it. To make it more complicated, if you do a WHOIS on gdotea.com, it shows tucows.com as the registrar, not Hostway. So I guess Hostway actually used Tucows to register the domain.

The other hard part is to set up my domains in NameCheap to point to my ASO server. I thought the way it would work is that I just enter the numerical address. But I can't do that. Instead I have to use a Domain Name Server. NameCheap has one, but I can also have NameCheap use ASO's Domain Name Server. I don't understand that and I don't see how I can tell NameCheap about the files stored on ASO. When I registered with ASO they asked what domain I would be using and I entered gdotea.com. But how do I get gdotea.org to point to the same place? ASO doesn't even know about gdotea.org so their DNS won't figure it out. NameCheap allows me to do URL forwarding where anyone who types in gdotea.org goes to gdotea.com automatically. So I guess I'll do that, though I thought it would be neat to be able to be able to have gdotea.org function with the same exact files that gdotea.com uses.

Actually I think this can be done by setting up a custom nameserver for gdotea.org on NameCheap. I go to Advanced Options and Nameserver Registration, then I enter the IP addresses supplied by ASO for ns1.gdotea.org and ns2.gdotea.org. Then I need to turn off URL forwarding and see what happens. [This didn't work. The IP's that ASO sent to me were for their nameserver which still doesn't know about gdotea.org. If I really wanted to operate gdotea.org, I believe I could send an e-mail to ASO and have them add that entry to their nameserver. I'm still not sure why I can't set namecheap's nameserver to point to my ASO space.]

There is also something called Dynamic DNS, but I don't know whether I need that. I think it depends on whether ASO will always assign the same IP to me or not.

Once I get all of this working, which could still take a week or so, hopefully I can cancel Hostway completely.

August 22, 2007


Recently I borrowed The Prestige from Netflix. While I wasn't crazy about the movie (B), one of the side characters was Nikola Tesla. I knew he was an important guy in the history of electricity, but his story really is interesting (not as interesting as the movie would have you believe). He is famous for Tesla coils which create huge lightning bolts in science fiction movies. On a practical side he was a proponent of AC electricity for home use despite Thomas Edison having everyone convinced that DC was the way to go. There is a monument to Tesla at Niagara Falls since his work turned their otherwise useless waterfall into a money-making electricity machine (see a NOVA episode dedicated to him).

Anyway, there were some really neat Tesla coils in the movie and it reminded me that I was interested in getting one of those plasma lamps. Since I had recently won a $25 gift certificate for using transit to get to work, I thought that the time had come. So the lamp is pictured below:


I was pretty excited to get the lamp and very relieved that it wasn't broken. In reading up on plasma lamps I learned that if you hold a fluorescent bulb next to the lamp that the lamp's energy will cause it to fluoresce. I wondered if it would work with a compact fluorescent and it turns out that it does (though not evenly):


Other than that, it really doesn't do that much. I was surprised that it uses a 12V DC adapter for power.

August 9, 2007

Bridge Collapse

A couple of people on the bulletin board asked me what I thought about the Minneapolis bridge collapse and what caused it. I wrote the following, which provides very little insight, but I haven't posted anything on the blog in a while. We were kidding on vacation that I would need to get back to help fix the bridge, but I was at least able to scan the documents I mentioned below which were requested by the investigators. Every bridge collapse causes engineers to change how we do our work, and this won't be any different even though it isn't known what caused the problem yet.

Here's what I wrote about why the bridge fell:

I don't think anyone knows right now, which seems odd because usually some likely theories surface pretty quickly. One of the problems with truss bridges is that each side of the bridge is a beam. Most bridges have a bunch of beams underneath the deck spaced out evenly. With this bridge, if one beam failed then that whole side fails and the rest of the span can't handle twice as much load (plus the rotation). Worse, since the beams are continuous over the piers, you lose multiple spans, so essentially the whole bridge fell.

I saw a report done several years ago where an investigating consultant was saying that the bridge was subject to fatigue problems (repeated bending, like when you bend a paper clip over and over until it breaks). So there could have been tiny cracks that finally gave way. Or it could be a corrosion problem that went undetected. But it also seems highly suspicious that repair work was going on at the time, so it seems like that will have something to do with it, whether they accidentally cut something they shouldn't have, or overloaded the bridge with equipment. GDOT was asked by NTSB to provide our rules for what kind of equipment can be placed on a bridge, but I'm sure they're looking at every angle.

Or it could be none of the above and the foundation failed somehow. Or something I haven't thought of. It is certainly being watched closely by all of the bridge engineers across the country.

One thing that is very bothersome is that it went so suddenly without any kind of warning. Bridges should be able to take a lot of punishment that would render them unusable or force them to be replaced, but without giving away completely. Even the bridge in Montreal that failed last year (from internal corrosion probably) had hunks of concrete falling off several hours before the bridge gave away.