Author: ntouran

don’t politicize nuclear power

I just saw parts of this release of the senate republican conference roundtable (1hr, 30m) recently, and was happy to hear reasonable talk here about using nuclear power to get us off coal ASAP. Can’t say I disagree. I am, however,  a little worried about nuclear power becoming a partisn issue (haha). This proposal is in line with McCain’s campaign promises of new nukes. I know plenty of people back in Ann Arbor who passionately hate Republicans and will blindly go on hating nuclear power for no reason other than to smite them.  Of course, those people are borderline insane. I think most people are actually reasonable: Rod Adams didn’t pull all support from nuclear power, but then again he’s the most pro-nuclear person on Earth. What about the people who have yet to decide how they feel about nukes?

You know what killed the early hippie subculture? It was the summer of love in 1967 when every 17 year old suburbanite became a hippie. And what killed the original punk movement? Hot Topic. Clearly, to undermine a group’s claim to identity, mainstream society has to claim its unique characteristics for itself (tie-dye shirts of the hippies, dog collars of the punks, and nuclear power of the Republicans). So, in order to keep nuclear power from being politicized, I’d like to see some non-Republicans voice their support in a way that identifies them as a non-Republican. For instance:

I love universal health care AND nuclear power!

or perhaps:

Boy, smoking bans are a great idea. So is the expansion of nuclear power!

Finally,

Ayn Rand sucks. Say, don’t you think making nuclear power plants is a good idea? I heard that if we recycle all the nuclear waste we have sitting around the USA, we could power the whole country for 90 years.

And you pro-nuke Republicans, recognize that it isn’t beneficial to the planet to try to tie a power source to a political ideal. So, when you rally for nukes, try not to demonize Democrats or anything. Sure it may be difficult not to sometimes, but rise above temptation and promote it as something too elegant to be automatically tied to abortion rights, gun control, and small government.

By the way, since nuclear power utilities are counting on large loan guarantees, doesn’t it seem like the nukes are more in line with Democrat’s “spend more tax dollars for the betterment of society” idea? Huh. Backwards.

If Al Gore endorsed nuclear power today, as a founder of Greenpeace has, we’d be this much closer to solving our energy problems.

Dear Al Gore: Please endorse nuclear power. Thanks  -Nick

online happiness

I’ve found four excellent things online recently and think I should re-share them to all zero of my faithful blog readers. Hi friends! Anyway, I just posted a rant about Twitter, so no need to go there again. That’s the first one.

My friend Adam showed me this excellent free PDF book by David MacKay called Sustainable Energy – without the hot air. It is straight talk about all the crazy myths and misconceptions going around about renewables and other energy issues. The first few items on that link are raving review one-liners by high-profile peeps. Well written with much infused sarcasm.

And from Slashdot, I read a bit of this pdf (A Mathematician’s Lament) on the status of the USA mathematical education system. It’s twenty-five pages of welcome truth. Again sarcastic and wonderful.

Finally, there’s the DropBox. I’d heard about it earlier, but at work in Seattle where I’m actually using 2 computers, it’s become invaluable. It seamlessly integrates into my file managers (My Computer in windows, Nautilus in Ubuntu, and I think Finder in Mac). When I drag or change a file in my designated drop box folder on any computer, it automatically synchronizes across all computers. It’s superbly wonderful. As a bonus, it’s web interface keeps versions of every single update. So if you want to go back to the file you overwrote 2 days ago, no problem, there it is. Click this link to accept my referral and give me 250 extra MB! Or this one to sign up without giving me a bonus.

the value of twitter

OK, I used to think twitter was stupid. I imagined it as just a big collection of facebook status updates. Personally, I couldn’t care less about you going to the grocery store. But then I went to the ANS conference in Atlanta and realized what the big deal was. You can embed tags in your twitter posts, using the # symbol. For instance, at the ANS conference, if you say something and put #ans09 in it, everyone who searches #ans09 can see what everyone who said #ans09 has posted. So you go there and it’s like: “hey a group of us here at #ans09 are going to max’s down the street. come on by!” You try #fremontfair for the solstice parade happening in seattle tomorrow and it’s all “PCC RT @amyhale: Getting prepped to live-blog, tweet tomorrow’s #Fremontfair the “Center of the Universe”! Watch 4 updates + audio too!”

Another feature: you can do it all on SMS on your phone. So imagine a group of people going out. If they all set their phones to “follow” the same person, he or she can just say: “ok going to Brown Jug now.” Or “going to Bab’s now.”  and everyone will get texts with that info. That’s actually new and useful communication right there.

So sign up for it. Do some searches for stuff you’re interested in. Up-to-date collective knowledge is at hand.

Actually the real reason I checked it out was all the buzz about the Iranians using it to organize protests. Apprently the US state department asked twitter to delay a scheduled maintenance window so the Iranians wouldn’t be left in the dark. Cool.

BTW, if you’re all interested in whether or not I’m at the grocery store, I’m partofthething on twitter.

car mp3 upgrades

I wanted to replace the LCD in my car, but I noticed there are new ones with buttons on them! So I’m thinking of reprogramming the car. I got mutagen to do ID3 stuff and will start just trying to make a simple playlist editor that searches like I want it to. Here’s the mutagen tutorial. I’ll need XML file saving again, just like in the CLScanner. I’m worried about how fast the searches will happen.

Aww, sweet. The code can load the entire library in like 2 seconds and search it in under a quarter second. Excellent. I can control mplayer using this code. The library and search functions took like, 10 mins to code up. They’re excellent. So all I need is a queue system, perhaps a separate thread that knows what song to play next. So there’d be the active thread, looking for commands from the keyboard and from the keypad, and the player thread, running mplayer and knowing what to play next. This might be too easy.

commands to do stuff in linux

Here are some nice commands.

Combine lots of pdf files:

gs -dNOPAUSE -sDEVICE=pdfwrite -sOUTPUTFILE=combinedpdf.pdf -dBATCH 1.pdf 2.pdf 3.pdf

Convert eps files to eps files with perfectly fitting bounding boxes:

epstool --copy -b file1.eps newfile.eps

Pull pages out of a pdf (more):

pdftk A=one.pdf B=two.pdf cat A1-7 B1-5 A8 output combined.pdf

Make a quicktime movie with ffmpeg:

ffmpeg -f mp4 -vcodec mpeg4 -i case3-flyby.avi case3-flyby.mov

Encode lots of jpgs to avi:
mencoder mf://hexes???.jpg -mf fps=10:type=jpg -ovc lavc -lavcopts vcodec=mpeg4 -oac copy -o output.avi

Convert pngs to jpg:
mogrify -format jpg -quality 90 hexes???.png

Shrink a bunch of jpgs:
convert -resize 20% IMG_2704.JPG sm_IMG_2704.JPG

Pull audio out of a video file:
ffmpeg -i was014.dv -ab 128 -ar 44100 was1.mp3

Play audio faster or slower without changing the pitch
mplayer -af scaletempo was1-fixed-up.mp3 . Use [ or ] to change speed.
(Note: you have to have a more modern version of mplayer to do this https://launchpad.net/~rvm/+archive/mplayer)

Run povray with 100 frames on the clock:
povray -W1200 -H1000 +kff100 hexes.pov

mc2 up and running, now europium case

OK! MC**2 is up and running on my VM. In comparing the results with those from new-down, I discovered that getting the side-by-side diff mode in VIM is really easy, and I don’t need that cream program anymore. Just use

vim -d file1.txt file2.txt

Then, use Ctrl+w to control the windows:

  • C+w C+w switches windows
  • C+w = makes the windows equal size
  • C+w < or > change the window sizes

Awesome. Here’s a screenshot of this great tool:

Using vim diff mode to see differences in MC**2 results
Using vim diff mode to see differences in MC**2 results

As you can sort of see, the results from my VM and the results from new-down match very well. Enough for me to use lappy laptop for lattice physics of fast reactors. It’s about 10 times faster than new-down, which is a 10 year old SPARC Solaris machine with a 450 MHz processor and 512MB of RAM. Processor info on this sun machine found by executing:

/usr/platform/sun4u/sbin/prtdiag

It’s snowing hard right now. There are about 3 new inches piling up. I had to wear ski goggles to work today.

As for the Europium case, I’ll need to deal with the fission product MC2 template. It has Eu151 through Eu157 as FPs, which I know from experience with Hf will cause problems when I try to add in more Eu at the top of the input. The question is two-fold: 1. How much of the Eu chain would we like to model explicitly? and 2. Should we disregard Eu as a fission product if we use it as a BP? The answer to the second might be easiest. If we are loading in Eu, the amount we load will be significantly higher than the amoun that would build up from fission, so yes, it is a good approximation to ignore fission production. As for the first question, Eu-151 and 153 are naturally occurring and the others all have short half lives on the order of 5-10 years. I’ll start by modelling up to 154, with absorptions above that going to the lumped fission products. All beta decays will also go to lumped fission products that Gadolinium is a member of (LFP41). With that in mind, I’ll eliminate all Eu except 155 through 157 from the fission product list in mc2FP.template.

The sfrCalc script is running nicely on the new VM MC**2 server. I’ve modified the templates to work with the Eurpium. Still working kinks out of sfrCalc script. Spent some time with 442 students and with Maru doing Origen stuff for Ewing’s class. The rebus run failed initially because the MC2 files had ZR  I and FE  I instead of ZIRCI and IRONI. I changed the table in the imd file for fuel-loading-eu in the templates folder to give the proper labels (t0 maintain compatibility with other templates I’ve used). After regenerating the cross sections, rebus runs.

Oddity: My nexenta distro has the wrong time.

compiling and installing MC**2 and dif3d in linux or windows

I thought the search engines were lacking in this topic that I have some experience in, so I figured I better do my part. I have installed MC**2-2 on a windows computer and on a linux computer using similar methods. The XS libraries I obtained differed from the results from my SPARC machine in the later decimal places, and global calculations were nearly identical. I haven’t tested all features, but it seems to work. I’ve also been running DIF3D 8.0 on my Ubuntu machine through a very ridiculous method. It runs in windows under Cygwin nicely.

MC**2-2 on a modern computer

MC**2 is a nice lattice physics code mostly used for fast reactors. It uses ENDF-V data and has excellent treatment of the unresolved resonances and stuff. According to my friends at Argonne National Lab, MC**2-3 is coming out soon, and it will compile easily on PCs. That’ll be nice, and it will make this discussion irrelevant. It’s going through verification right now. Anyway, until then, here’s the general idea. Get VMWare server and install Solaris 10 for i386 on it. This comes with the f77 compiler that MC**2 can actually use. Once you have that all installed, go in there and extract the MC**2 source. Edit the mcc.f file. Make these code changes:

  1. on line 12029 change REAL*16 to REAL*8. x86 architectures don’t support quad precision
  2. on lines 32858 and 32859, do the same.
  3. starting on line 32900, uncomment the lines with DEXP and DLOC and comment out QLOG and DLOG for a total of 4 changes ( 2 uncomments, 2 comments).
  4. Same on line 32937, but only one swap this time.
  5. Add an extra space before the text on line 44534. This is some error in the RSICC distribution.

I’ve done this on Solaris 10 with great success, and now I’m trying it out on OpenSolaris, on my new external hard drive. I had to give it 1GB of RAM or it was crazy slow. OK it works in opensolaris too. Here are the steps:

  1. gunzip and untar p350tar1.gz
  2. edit exec_compile.mcc.sun script and change the lib and jobdir variables to where ever.
  3. make the code changes to mcc.f as discussed
  4. run a copy of the script with the uncompress and copies commented out so it doesn’t overwrite your changes (I did this a few times)

I had to turn optimization in the script from O3 to O2, or else I got a core dump on compiling mcc. f. If all goes well, you should have the MC2 executable.

Now you have to make the libraries. The code to convert libraries needs similar code changes. Change All REAL*16 s to REAL*8, the QLOG to DLOG, and the QEXP to DEXP. It will compile now. I added the cwd to my path and the script ran nicely. Notice that when you change the code, you can’t just re-run the script as is because it uncompresses the original files each time. I made a copy of the script and commented out all the uncompresses after running it the 1st time.

My last pitfall was that there was a write-protected ISOTXS file in the directory I was trying to run in and MC2 dumped the core on execution. I deleted this file and reran with wonderful success.

I witnessed one of the guys who lead the development team of Windows 3.1 try to compile MC**2 once with the intel ifort compiler. He got it compiled, but it failed at runtime with memory allocation errors. That’s the story of my life.

DIF3D8 on a modern PC

DIF3D 8.0 compiles with G95. I followed instructions I found here to do it. I did run into a problem, however, with memory allocation when running on Linux. In Windows XP, under Cygwin, the instructions work perfectly. I am able to run in Linux by using the Cygwin-compiled executable through WINE. This is, conceptually, extremely ridiculous as it is using an emulator to run a program which is emulating the platform that I’m on. Go figure. The bottom line is that it works and it runs quite quickly — moreso than on the ancient solaris machines I used to run on. I think it should be quite easy to get it working natively on linux using G95 with a little effort, so let me know if you figure it out.

Cross section libraries

When transfering XS libraries from one machine to another, it is important to do so in ASCII, or BCD (binary coded decimal) mode. When I run MC**2, I get a binary ISOTXS file that will not transfer nicely to other computers. I use a utility to convert this to ISOBCD, which I then convert back to ISOTXS on the computer I’d like to run on.

nse out, now bibtex

I sent my prof.  my version of the manuscript. Now I’m trying to get the proper citations for Nuclear Science and Engineering with bibtex. I’ve been running into Charles Karney’s physics journal bibtex styles, but I haven’t gotten them working yet. They say to run them through the c preprocessor to get different styles, but I just get errors like:

physics.bst:9:19: warning: missing terminating ‘ character

physics.bst:3484:7: warning: extra tokens at end of #else directive

Ah. This is because cpp has decided that it shouldn’t be used for processing anything besides actual source code. Well, thankfully they left in the -traditional-cpp option. So if you use

cpp -P -traditional-cpp physics.bst nse.bst

It will actually work. That’s excellent. This is nice.

[1] C. Tzanos, E. Gyftopoulos, and M. Driscoll, “Optimization of Material
Distributions in Fast Reactor Cores”,    Nucl. Sci. Eng.  52, 84 (1973)

Here’s a nice cheat sheet for VIM. I’m using it to capitalize the first letter of each word in my bibtex.tex file. I’m sure the bibtex style can do this but I’m not bothering.

Here’s the final product: nse.bst

UPDATE: I put double quotes around article and techreport titles, as discussed here.

Also, fonts from my LyX install were really fuzzy when printed. I went into document settings and changed font family to Roman and set font to Latin Modern Roman and now the fonts don’t get fuzzy when you zoom in so I’ll assume they don’t get fuzzy on print either. Let’s hope not.

I also just added a reCAPTCHA plugin to this blog. It works. My simpleCAPTCHA plugin wasn’t showing the image, nor was it even showing up in the plugin list. I renamed the simple-captcha folder in my plugins folder and now recaptcha is in charge.

I need to call Jeff soon to tell him he’s publishing this.

thorium workshop, 2nd iteration

I’m at the thorium workshop here at school. There’s a guy from Thor power in Norway giving a talk. It’s interesting.

Fleming just suggested BeO as a moderator in a Th reactor. It’s diffusion length is just right (more than water, less than graphite), it won’t burn like graphite in air, and it increases your beta-effective with it’s delayed photoneutrons and stuff. I should tell will this.

But I’m actually working on BP stuff. I ran the BP search before the TRU search on the 2nd iteration of case 2. The BP search direction is loading correctly now, but it’s not covering the full power peak. I’m going to get power plots that correspond to the search direction plots now. It was very simple to do with my plotSearchDir2 function. (I have a good library I guess). It’s very useful to see these two together, layered on top of each other with the compiz fusion opacify functionality. Wow.

My mpeg4 povray videos didn’t work on JCLs mac computer. I’ll have to look into that. Ah, mac’s don’t support the avi container. I did this:

ffmpeg -f mp4 -vcodec mpeg4 -i case3-flyby.avi case3-flyby.mov

to convert it to quicktime and sent it to him to see if it would have worked. It did.

There are asymmetries that show up in the 2nd iteration of the v4 case. They’re worse in the 3rd iteration. None help the peaking factor. What the heck. Should have gotten 1/3 core model to work. Must finish manuscript. Will stick with 1st iteration.  Damn damn damn.

second iteration, screen magic, new line search

First thing I did this morning was install the AntiBotQuestion mod in my phpBB3 forum for whatisnuclear.com. Spam bots were getting in so I had to shut them down. Unfortunately it didn’t stop guest posts, but I went to the forum and found an extra few lines to add and now it seems to work. Only issue: if you get the captcha wrong, the anti-spam question doesn’t show up in the re-try page. I’ll try to narrow that down later.

I got a nice plot of the 2nd iteration search direction for case 3. It didn’t yield any improvement, however. That’s too bad, or good. Apparently my linesearching is phenomenal. Maybe I should run a few cases of CORTANA BEFORE doing BDT.

Concerns about the BP search not doing anything persist. As expected, the class 1 enrichment increases each time I add BPs. This increase obviously counteracts the effects of the BPs, but it should at least bring the peaks at BOC and EOC closer together. Ope, I noticed the HF concentrations are all identical. Let’s make them natural. Which Hf isotope is the best absorber? Off to the NNDC. According to my chart of the nuclides, Hf-174 is 0.16%, 176 is 5.%, 177 is 18.%, 178 is 27.&, 179 is 12%, and 180 is 35.% Here are all their cross sections:

Hafnium isotopes absorption cross sections
Hafnium isotopes absorption cross sections

Jeff talked about Europium a lot. Here’s a comparison of The two natural isotopes with some of the better Hafnium ones:

Absorption cross-sections of Hafnium and Europium
Absorption cross-sections of Hafnium and Europium

Yeah that Eu-151 is pretty rocking. Given more time, I would put that in. For now, I’ll either admit that the BP searches didn’t do anything, or leave them out completely.

Time to give Professor his slides. If you import EPS into GIMP, make sure to turn the anti-aliasing filters on. OK sent them off. I went up and talked them over with him and he gave me a few tasks:

  1. Switch TRU enrichment one high means add and low means take out. I thought this was done already. Check negative jump. Yeah, in positive jump parameter cases, the search direction is switched by the line search, but the plots will still be wrong. Need to swap them in plotting too for intuition.
  2. Do a fly-by animation. YES! This is going to be hilarious. It’s rendering now. I’ll put it on youtube soon. (here it is)
  3. Remove empty hexes in the core map image.

While doing this, I realized that the BP search and TRU searches shouldn’t be switched from each other. It just worked out that way because they’re both accomplishing the same work. It’s on the 2nd iteration that the BP search might make more sense. All I have to do is work on my line search parser, making it that it reads old controls and updates them rather than making a whole new set each time. hmmmm. Exciting. This also explains why the BP search isn’t doing much. It’s not changing things in the right places. Let’s design a new line searcher

New Line Search Ideas

Currently, we have binned regions based on search directions to have values centered around 1.0, with min and max of  0 and 2. Additionally, the BP line search has the capability of setting any value less than a certain cutoff to zero. Both TRU enrichment modification factors and BP EF priorities get set directly to whatever is in these bins. This makes good sense for the first iteration, where everything is set to 1.0. But in subsequent iterations, these values should represent percent changes in the current value. So if we have a 1.05, increase the current value by 5%. That’s pretty easy.

I’m starting these changes on revision 10. Will start with BP search because it doesn’t work well anyway. Hmm, it’s not so simple as to just doing this multiplication though, because if I want to just increase the size of the feed each time, I don’t want the priority distribution changing. Obviously, I want to separate increase feed size into a different function. Duh.

Linux screen utility wonder

I did learn that I’ve been using screen wrong the whole time. You should only start a screen session once! Not once for each window. Press Ctrl+a, A to name your window, Ctrl+a, c to react a new window, Ctrl+a, ” to list all windows…. etc. How great is that. Productivity just increased. Here’s where I read about it.

nse

Back to work on the same old. I figured out the grayscale images yesterday, but I still need to generate them for all the new uranium cases that don’t have thousands of kg of Hafnium in them. Additionally, I’m going to add a picture of the adjont source in the 1-D slab. Will need to try to make it eps. On it. Running the analytic oned solution now. I chose search and will see what we get. It’s been a while since I ran this code. OK I got a decent plot out. I used TeX text processing on it and it looks phenomenal. Now to generate the B&W ones for three cases…

In case 1, the 0-th timestep jump parameter is negative, so we need to switch the sense of all search directions. Run.py can handle that now, with the N option, for “negative.” That’s revision 8 in the itd svn repository. Rerunning v6 case with proper sense. Let’s see if we can do better. With improper searching, we started at peaking factor 1.05038 and got to 1.04 by bp search, and to 1.039 by end of BDT. Lame.

Uhh. I just spend 1.5 hours with MCNP crap for a student in my class. Why are we struggling with MCNP when we should be learning reactor analysis? Damn another hour with the class! These guys are killing me.

Well here’s some instructions I just made for doing safety analysis of SFRs in REBUS or MC**2:

<!– @page { margin: 0.79in } P { margin-bottom: 0.08in } –>

Disabling the criticality search in REBUS

by Nick Touran

If you want to perform any kind of basic void coefficient, Doppler coefficient, or temperature coefficient of reactivity estimations in REBUS for fast reactors, you have to disable the criticality search. Here’s how.

  1. Run your regular base case of interest. Look at the output for the final value of the enrichment modification factor. You will find a edit like this near the bottom:

++++++++++++++++++++++++++++++++++++++++

+ +

+ COMPLETION OF FINAL SEARCH PROCEDURE +

+ +

++++++++++++++++++++++++++++++++++++++++

THE ENRICHMENT MODIFICATION FACTOR IS 2.36759E-01

THE BURN STEP TIME IS 2.10483E+02 DAYS.

Note the factor. You need to put it into your perturbed file.

  1. Make a new rebus and MC**2 case with the perturbations you wanted. Decrease the sodium density, decrease the fuel density, eject a control rod, whatever.

  2. In that new rebus input, go to the A.BURN card 4. You should see a 1.000 representing the desired k-eff at EOC. After that, there is a convergence criterion, probably set to 0.0001 or so. Change it to 1.000. This disables the criticality search.

  3. The last two numbers in that same line are the first and second guesses of the new enrichment modification factor. Change the first one to the factor noted from the previous output file. Keep in mind that you can only put this number between certain columns. Check the manual to see which ones. Be careful with this!

  4. If there is a burn cycle time search enabled as well, disable it in the same manner (on card 3 though) and insert the burn step time manually!

  5. Now criticality search is off and you’ve manually set the critical class 1 enrichment. You’re ready to run. Run your new rebus case and compare k-effs with those from the base case.

Notes:

If you change a density somewhere, make sure it changes in the cross section library calculation too! The energy self shielding can vary wildly with different densities.

This method of calculating safety parameters should be taken with a grain of salt because it does not account for any anisotopies that you may see in real rod ejection accidents, etc. Diffusion theory is only an approximation of transport! Try using some perturbation theory codes like VARIANT if you want better results.

Have fun!

OK. What else? The new line search behaved very well. But in v5, the big case, the reactivity swings are all miniscule! 1.001 at BOC? Say what? Investigating. The core is breeding plutonium. It’s a breeder. Ah! Well the plenum had the wrong material, it looks like. I fixed it in the CORTANA input maker to agree nicely with the Hill cases of old and am now re-running just the first rebus case. This large case requires a very low guess of the enrichment modification factor.

Hot Tub Controller

So, I have to tell you about the hot tub project. It’s been going on for a few weeks now and we just basically finished it. I (with some help from Jesse) have set up a microcontroller to control and monitor the hot tub. We have a temperature sensor mounted on the heating element tube and we wired in a relay to control when the heater turn on. Then we wrote code to allow it to interface with email, the internet, and even text messages! For real. Look:

Text message from the hot tub
Text message from the hot tub

Haha! Here are some more gems:

Temperature plotsand you can control it with this form:

control_formOr you can just control it from the command line:

terminalSo here’s what’s going on. Firstly, there’s an arduino connected to a USB port of the computer in the basement. Here’s a pic:

ArduinoOne of the digital pins on the Arduino is connected to a OneWire bus with three temperature sensors hooked up to it with a pull-down resistor connecting the bus to the 5V line. That’s the green wire. The ground is white ground.  The three sensors are hooked up (in parasite power mode) to 30 feet of indoor/outdoor CAT-5 wire from Home Depot. I surrounded each temperature sensor with a piece of 3/8″ O.D. copper tubing (which is miraculously already corroding) and pinched them down and sealed them up with Silicone. Here’s a pic of the outdoor sensor.

Outdoor temp sensor in copper

Anyway, yeah. The last sensor, the one on the tub, is wrapped in lots of insulation from the hardware store to try to keep the outdoor temperature from affecting the hot tub readings.

On another digital pin (the orange wire), we have a relay circuit that we can turn on and off easily. In the hot tub, it connects the wire that connects the coil of the main heater relay. So it’s  a relay for a relay, effectively. We just set the temperature dial very high and use the Arduino to cut it off when we want. We got the circuit from here. Here’s a copy of that:

schematic

Nice. I used a relay that can handle up to 30A, 240V, with a 12V coil. I got the 12V by splicing off of the hard drive power cable inside the computer (blue wire, with white blue as ground. That’s the same ground, but we didn’t want to tap into the fragile cat5 wire again). That’s unfortunate because it requires the computer be on to have the heater on. A better design would not rely on the computer to maintain control of the hot tub.

The rest of it is just software. I’m using the pySerial module to read and write to the USB tty device in 32-bit Ubuntu 8.10 Linux. The code that I compiled on the Arduino chip simply accepts simple characters through the serial port and does as asked. It knows how to turn heater on, off, read temperatures, and tell whether or not the heater is on. I’ll build some safety logic in soon. Right now, all the control logic and communication is done in Python on the computer. I have an Arduino class that abstracts the commands the Arduino knows. Then there’s the hottubController class that checks the sensors and turns the heat on and off accordingly. It calls the communication class, that checks for commands in an IMAP email account, submits temperature information to a MySQL database on my server, and sends command responses via SMTP. The text messaging functionality works simply because you can easily use the text-to-email gateways used by many major phone companies. The MySQL stuff is done with the MySQLdb python module, which is fairly simple.

The web form is a python cgi that makes that simple HTML table and sends the commands in. The plotter is another python script that reads the database and puts the data into an HTML file, which is then parsed by the flot JavaScript plotting routines on the clientside, allowing zooming and dynamic date x-axis labels, which are awesome.

Still to come: predictive hot tub times. Since the heating is very linear, it’s possible to extrapolate the time at which the tub will reach a given temperature. You’ll get a text that says: “the hot tub will be ready at 10:37PM” How cool will that be at the bar?

With all the copper, casings, arduino, sensors, relays, silicone, insulation, and various other tools I bought during this, it’s up to about $100, not including the computer. Not bad!

More Details

In case you’re wondering or debugging the hot tub controller, here are some more details.

The breadboard setup for the hot tub controller
The breadboard setup for the hot tub controller
Here's what the arduino wires look like. Nothing special.
Here's what the arduino wires look like. Nothing special.

Out at the hot tub, you’ll see a silver toggle switch. Under normal operation, this should be in the center position. To shut down special features and go back to plain-old hot tub, put the switch in the up position. This gives control of the hot tub back to its internal thermostat. It also disables the 10 second heater delay relay.

Too much information

I do a lot of stuff each day, and then forget most of it. Sometimes I learn something, sometimes I get a thesis topic, sometimes I do a fun project or have a nice thought. I think a wordpress page might help me organize and remember what I do with my life. That’d be nice.

Today, I spent most of the day making a new webpage for whatisnuclear.com. You can find it at http://www.whatisnuclear.com/articles/recycling.html

Since Obama zeroed out the funding for Yucca mountain, Prof. Fleming, Kearfoot and I think it’s a great time to start recycling. I made this page to help explain exactly what that means and why it’s good.

I then went to Sweetwaters and got some Chai with skim milk. It was delicious! I opened up the lappy laptop and worked on my single goal of the evening: plotting search directions in a manner similar to the input maker. I searched for some kind of wxPython colormap, but didn’t find anything and then luckily found that Matplotlib has all the capability I need. Using the scatter function, you can specify hexagon symbols with arbitrary angles. Excellent. Check this plot out:

Burnable poison search direction for timestep 0
Burnable poison search direction for timestep 0

Yeah. That’s excellent. Now I just have to figure out how to get it to size automatically.

Ceris brought a recent The Economist over with some legalization of drugs propaganda. They’re position has been to legalize the drugs, and spend the billions on treating addiction instead of jailing recreational users. I agree. It had other articles that caught my interest, specifically some on the clean coal myth, solar collecting balloons, and devices that charge wirelessly. That got me thinking that my camera batteries never charge anymore. So I went online and bought a well-reviewed charger, thinking that maybe my Ni-MH chargers are both defective, since all 12 of my batteries don’t last in my camera anymore.

I watched the rest of RENT last night with Adrienne and dumpster girl. I never knew what it was about. I kind of liked it, although I don’t have much profound thought about it. It’s been a lazy weekend. The most important accomplishment was the completion of the hot tub controller project. More on this once my camera works again.