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Fire in the Sky 2007

May 28, ’07 10:29 AM

I just got home from Fire in the Sky 2007 in Mansfield, WA.  FITS is Washington Aerospace’s spring high-power rocket launch, drawing folks from all over the western U.S. for three days of launches and extreme engineering geekiness. 

My friend Bill Barnes and I both tried for, and achieved, our NAR Level 1 certifications, allowing us to build and fly rockets requiring motors with more than 62.5 grams of propellant, and giving between 160 and 640 Newton-seconds of total impulse.  I flew the PML Phobos, with a 29mm motor adapter in the 38mm motor mount, to accomodate the H128W motors we used for certification.  Both of our flights went picture-perfect with motor ejection; I used a 36" chute with central spill-hole to bring the rocket down gently but fast and straight.  I don’t have a good picture of the Phobos launch, unfortunately — the H128W took it off the pad faster than I could hit the shutter release.  But Bill and Susan might have video of both our cert flights, so that might be forthcoming when we can get it transferred.

After trudging through the sagebrush and getting woozy from too little water, too much sun, and no
food, I recovered theDsc_0010 Phobos (with spotting help from Bill – thanks!) and we completed our cert. 

At this point, since I was covered by Kent Newman’s LEUP (thanks!), I was able to fly the Giant Leap Elipse.  In order to get the CG properly positioned about 4 inches ahead of the CP (center of pressure), I had to load fishing weights (and a couple of extra AA batteries) into the nose cone.  With the 48" TAC-1 parachute, MC2 flight computer, and a 38mm I357 motor, the Elipse weighed in at 7.5 pounds or so — a heavy rocket but the I357 had plenty of punch to get it off the pad The Aerotech I357 generates a total of 342 Newton-seconds of impulse, with a peak thrust of 432.8 Newtons.  As a comparison, if you’ve used the black-powder Estes model rocket motors, the D12 delivers a total of 16.8 Newton-seconds of impulse, and 29.7N maximum thrust — so the I357 is delivers about 20x more thrust than a D12.   

The Elipse launched perfectly and the TAC-1 chute was easily visible in red and black against the clouds.  I managed a picture of the launch itself (shown here, click for a bigger version), which generated a fairly impressive smoke trail and nozzle flame.  To get a sense of scale for this picture, the Elipse is 6.5 feet tall and 3 inches in diameter.  Recovery was easy since it drifted back towards the pads.  I’m thrilled at how the weekend went, and eager to build something new for August or October. 

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All quiet on the northwestern front…

May 12, ’07 10:21 AM

It’s been a quiet week online, principally because I’m heads-down on my dissertation proposal after returning from Austin. It’s going fairly well, but slow because I’m also reading a ton of academic literature I missed during the decade I was away. The archaeology portions are the toughest, actually, but it’s more idiosyncratic — it’s a matter of looking at the evidence and people’s analyses of it, and it doesn’t necessarily have a “structure” you can work out. Paradoxically, I find the literature on evolutionary theory, game theory, and the evolution of cooperation much easier to absorb in bulk, because once you figure out the underlying mathematical structure of the various models, a lot of the literature is easy to “slot in” and move through rapidly.

The weather is getting good up here, and that means more grilling on the deck and weekend guests, which I’m looking forward to. I like the contrast of the winter, with a bit more quiet time enforced by the wet, cold, grey weather, and the bright summers with plenty of visitors. I’m probably cutting back on Seattle time over the summer, to maximize my time up north while it’s so beautiful, but I’ll still be down in Seattle for short visits fairly often.

Over Memorial Day weekend, I’m headed to Fire in the Sky, the spring high-power rocket launch in Mansfield, WA, with my friend Bill Barnes and his family. You can check out the stuff I’m building for FITS here. Either this, or the smaller Public Missiles Phobos will be my Level 1 certification flight, after which I hope to launch a couple more times over the weekend if all goes well. It should be an interesting, if incredibly nerdy, weekend. But a little bit of engineering is a good thing occasionally.

Back to the proposal…

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SAA Meetings in Austin

May 3, ’07 10:22 AM

Last week, I attended the Society for American Archaeology conference in Austin, for the first time in several years. Austin was a great town for the conference, but sad to say I didn’t get any truly good BBQ. IronWorks was OK, and Stubbs was fine for lunch, but we didn’t have a rental car this time and Salt Lick was out of reach. Despite this, we had a great time, and I caught up with folks I hadn’t seen in years, like Chris Pierce, who’s working on semantic web database technology, Terry Hunt, Lee Lyman, and many others.

Poster sessions were terrific this year, with plenty of space to walk around and see everything; increasingly I find that spoken talks are much less interesting, particularly when people have few slides and read their written-out talks in a flat monotone. How do people expect to convince or interest an audience without a strong presentation style?

Among the interesting papers I saw were two papers on costly signaling theory by Aimee Plourde (of UCL), and Jillian Galle (Monticello). Another paper by Colin Quinn and Ian Kuijt on signaling in the Natufian was also interesting, but I need to see a written copy to follow their argument on how they link Natufian burial behavior to costly signaling.

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TransmissionLab Update

Apr 6, ’07 10:44 AM

Yesterday I posted TransmissionLab version 1.4, a fairly major reworking of the model class core. I was dissatisfied with the way that RepastJ models, by default, seemed to tightly couple the main model class to all of the other classes I’d written for data collection, transmission rules, and population construction. My goal with TransmissionLab is really a framework for building models to study cultural communication and transmission, not just writing one giant model and bolting new stuff on.

A paper by Railsbeck et al., in the September 2006 issue of Simulation, is right on the money in saying that the original Objective-C version of the Swarm toolkit is a strong “framework,” as opposed to the “library” style of successor toolkits like RepastJ and MASON. Swarm definitely forced a style of organization onto your simulation models, via the concept of nested “swarms” of agents, observers, etc. I suspect this is much like Ascape, but the latter doesn’t seem to be an active development project any longer (at least given the website – leave a comment if this incorrect). Whereas Repast provides a ton of infrastructure but simulation models themselves seem to be fairly unstructured, as I read various examples and models folks have posted online.

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Robert C. Dunnell’s graduate theory courses online!

Mar 29, ’07 2:32 PM

While I was down in Long Beach recently, Carl Lipo and I talked about digitizing a series of video tapes made in the mid-1990′s of the last time that Robert C. Dunnell taught his graduate archaeological theory courses. Carl has found the time and some resources to start doing that, and the first couple of files (representing the first 5 or so class sessions) are now available in Windows Media format on his website. The classes are an amazing resource and learning experience. We have to apologize in advance for sound issues in lecture #2 — the colleague (who shall remain nameless) who was auditing the class and taping the lectures for us had some….technical issues.

Carl is digitizing all of Archy 497, the first of two quarters of archaeological theory. In 497, Dunnell focused on “formal theory” — concepts, key conceptual relationships, and the classification tools necessary for all explanation in archaeology. In 498, which likely will be the next digitizing project, Dunnell focuses on “explanatory” theory and the history of archaeological theory.

For those readers unfamiliar with R.C. Dunnell, he was my former academic advisor, longtime Chairman of the Department of Anthropology at the University of Washington, key initiator and driver of Darwinian approaches to explanation in archaeology, and scourge of generations of first-year graduate students. Dr. Dunnell retired in the mid-1990′s and now resides in the Southeastern United States, surrounded by Mississippian mounds, archaeological sites, and decent BBQ joints.

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TransmissionLab Version 1.3 available

Mar 29, ’07 2:25 PM

A small update to TransmissionLab is available, which enables proper batch-mode operation and simplifies the command line acrobatics required for batch mode operation. This version is numbered 1.3, and is available either in source code format (from the Google Code Subversion repository) or as a binary JAR file release. The latter are found under “Downloads“, and include a matched JAR file, a ZIP file with library dependencies, and an example batch-mode parameter file.

Both the batch-mode parameter file and library dependencies have slight differences from Version 1.2, so be sure to grab both otherwise you’ll encounter errors starting up a simulation. In particular, this release adds a dependency upon the Jakarta Commons CLI library for command-line parsing, since this isn’t a strong suit of the Repast libraries.

This version also adds one statistic to the OverallStatisticsRecorder data collection module. For each simulation run, we calculate the average number of agents who have traits (measured at each model tick) which are listed in the “top N” list of traits. In other words, if you’re working with a “top 40″ list of song-analogues, this statistic measures the number of agents whose chosen trait is a song in the top 40, as opposed to a trait that wasn’t frequent enough to make the top 40 list. This statistic is thus paired analytically with the parameter for the size of the “top N” lists, and the combination of the two should be interesting to examine across a range of mutation rate and population size parameters.

On a related note, LiveScience has an article on the upcoming article by Alex Bentley, Carl Lipo, Harold Herzog, and Matthew Hahn. I recommend it for a somewhat popularized account of the main conclusions of their 2007 paper. Since much of what we’re doing with TransmissionLab at the moment is going further along the lines suggested by Bentley et al., and earlier Fraser Neiman, Carl Lipo, and myself, it’s a good clue to the kinds of phenomena we can explore purely assuming that choice among alternatives is statistically random or neutral.

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