Sunday, February 27, 2011


pocket / keychain calipers? that would be an interesting design challenge (is it even possible)

todo: create public wiki, anyone can login with certificates and edit (for use for hosting class websites etc.).

todo: submit a good post to MIT writing center for critique

Sometimes I feel like 2.007 wants us to violate this. Yea, we're MIT students, but we're also just like any other human being who has never built a robot before:
    • Don't reinvent the wheel! Search the web for how other people did things, and copy them! It may be unoriginal, but hey it is your first robot, don't expect to develop the theory of relativity on your first try.
"We want to break the graph where time experiences insane ramp-up during last three weeks" -- well, uh, look at the calendar. What times are majority robot-building, and what times are filled with hand-holding Milestones and homeworks and such? Maybe I'll come to realize their usefulness, but I would like to build my first robot, get it to work, and then run calculations and iterate on the design. (aka, I don't want to do homework and I want to get credit for doing things I like doing in my spare time anyway, heh).

Wednesday, February 23, 2011

Greenhouses and Biodigesters: Research

Yay, I hope La Vaquita gets the vote in Dell's Social Innovation Competition!

My technical summary:
Build biodigesters in rural Mexico. Biodigesters take in organic waste and produce both fertilizer and biogas. The biogas can then be burned to heat a greenhouse that protects the biodigester, keeps the biodigester at working temperature during the winter, and can furthermore serve educational purposes for children and eventually grow high-value crops to improve the income and/or nutrition of farmers. Both the biodigester and greenhouse can be made mostly from recycled (thus, low-impact and low-cost) materials.

My Elevator Pitch:
We believe that cow poop is gold. Cow poop: providing income, education, sanitation, and nutrition. Benefiting the environment at low monetary cost, using techniques known for hundreds of years. Biodigesters take cow poop and produce sanitary fertilizer and biogas, which can in turn be burned to heat a greenhouse.

Side Note: There is a flux of terms around this idea. Biogas, biodigester, biogas digester. They all refer to anaerobic decomposition, as compared to composting, which is aerobic decomposition.

Anyway, so the idea (our idea? if I'm in on this) isn't particularly innovative by my standards, which works out because I agree that really, we could focus on implementing proven good ideas, not just coming up with / funding the New Idea of the Year. And there is a clear gap between good ideas and implementation around the world. And we can be innovative in terms of delivery and business model in combination with this technology.
Based on a few internet searches, I would actually say that we have proof (although our own working prototype would be excellent, regardless of local or at MIT) that this concept works. There's even been economics analysis done which raise hope that our intuition is correct and can give us guidance in implementing our own studies.
For instance:
main reasons for failure including: damage to the plastic that holds the gas and waste effluence, general neglect, and a lack of follow‐up and proper system maintenance
Sounds like opportunities for a business model to me.
Oh look! IRRI stands for International Renewable Resources Institute-Mexico. We should talk to them. And they had the same greenhouse idea.

For me to read: all the documentation at <3 It makes me happy whenever I see public documentation.

General reading:
  • Does not specifically address tubular (salchicha) biodigestors, but awesome overview:
By Eric Buysman, GERES Cambodia,
4 pages.
Biogas technology is marginally implemented in cold regions. Most projects are of pilot scale in specific niches, all learning by doing, and it is therefore impossible to extract a best practice. We should however, not look at experiments for biogas alone since there is significant learning from the experiences with greenhouse construction and passive solar housing at high altitude regions.  The results from these experiences could be combined to design an integrated system, which tackles a wide range of problems among poor households about the lack of sanitation, energy poverty, dependence on non-renewable polluting biomass, low income and the short growth season of crops.  An integrated approach is the best solution to tackle poverty from the grass roots level, as it both reduces fuel costs and increases income. Financing biogas a program requires an approach that is aimed at both decreasing the investment barrier (microfinance, subsidies) and on providing the means to increase household income (capacity building and extension programs).
  • High Altitude (below freezing) biodigesters in Bolivia, awesome guide in Spanish:
Biodigestores familiares: Guía de diseño y manual de instalación. 2008.
Biodigestores de polietileno tubular de bajo costo para tropicó, valle, y altiplano
J. Martí Herrero, GTZ-Energía. Bolivia.
80 page manual.
(originally from:

Some studies:
Science Direct search: Biogas Greenhouse

Some miscellaneous: (note key measurements in the studies) (see references at bottom, listed here for people like me on netbooks that multiple site loading times):
Science Direct: Landfill Biogas for Heating Greenhouses and Providing Carbon Dioxide Supplement for Plant Growth Positive Effects of Carbon Dioxide
Slideshare: Alternative Heating Opportunities for Heating Greenhouses
You do not need to remove the CO2 from the gas to burn it, but you should obtain a burner that burns biogas. The CO2 released will encourage plants in the greenhouse to grow faster, so it should be possible to release the exhaust gases into the greenhouse. ... The main problem with burning the gases inside the greenhouse is getting the heat balanced within the building. A burner will release large amounts of heat in one place, so you need a system to circulate this heat to get the whole greenhouse at a uniform warm temperature. A boiler can be used to heat water, which can be pumped around heating pipes. Alternatively, the flue gases can be mixed with a larger quantity of cold air, to get the correct temperature, before it is vented into the greenhouse via air ducts.
 Some videos:
"complete installation of a biodigester in the altiplano (cold climate) of Bolivia"

Tuesday, February 15, 2011

Things learned, Feb 15th

Things I learned recently.

"Overhead is an utterly meaningless metric of organizational efficiency (or anything else). It is basically a relic from decades ago when low organizational cost was incorrectly associated with “efficiency.”
2. When responding to strikes (sparring), focus on the shoulder area, not the hands. I instantly felt the difference in speed when a sempai (in American Jiu Jitsu) told me this.

3. Polio eradication issues in Nigeria may not have been mostly "health belief" problem as was reported (specifically, Muslim clerics denouncing the vaccine). There were political issues (between the government and INGOs, international NGOs like UNICEF and WHO). There was also the issue that polio was often not a priority in communities.
(This speaker*, however, also thought that smallpox eradication had issues -- that because the community as a whole wasn't improved, the same child who is today saved from dying of smallpox dies of TB, measles, etc., today).

* Dr. Mukherjee, at the first lecture of "HST.184  Health Information Systems to Improve Quality of Care in Resource-Poor Settings." Lectures were filmed and will be posted online eventually.

Wednesday, February 9, 2011

1 cm dot grid letter-size template, pdf & svg (for use as notebook paper)

I prefer faint dot grid over a) lined paper b) completely unlined paper (easy to write sideways) and c) box grids.

So I created 1cm dot grid paper, letter-sized for my 2.007 notebook (yay Inkscape). There are markings for roughly quarter page intervals, a header, and a footer.

a close-up of the pattern
Copytech copies pages at 5 cents each, and binds (for notebooks less than 80 pages, GHB binding) paper for $1.50 (larger sizes and different bindings cost more).

To print one or two copies, open it up in Evince (on DebAthena). Ctrl-P, select a printer, enter 1 or 2 copies, and make sure it says "Long side" (to print double-sided and have it flip the right way) and "1 to a page." Also, quality set to "600 dpi" (which it is by default), otherwise it won't print correct.
Alternatively, hit Ctrl-P, and type lpr -P[printername] -Zduplex -h 
("h" to toggle header on/off, duplex to print front and back)

Tuesday, February 8, 2011

Solidworks on an Ubuntu netbook? A Howto for MIT MechE undergrads

yo, I heard u liek solidworks so i put a solidworks in ur windows7 in ur desktop, and put that in ur ubuntu in ur netbook
TECHNOLOGY FTW: making life complicated since 10,000 BC

Ah, the life of a course 2 (MechE) major, where everything I need is Windows-only.

Here's the situation:
2.007 recommends that we install Solidworks on our laptops.
Solidworks only runs on Windows.
I only run Ubuntu. On mai netbook. :)

Possible solutions:

  1. Dual-boot XP: well, I hate rebooting. Scratch that.
  2. Install XP inside a virtual machine on my netbook: Works under casual inspection
  3. Triple boot windows 7 on my desktop, install Solidworks, and remotely connect to that:
    The Win!
    Specifically, using the RDC protocol, Windows 7 on my desktop, and remmina on Ubuntu Maverick on my netbook.

I have: a netbook (1.6 ghz, 2 gb RAM, 160 gb drive) running Ubuntu (Maverick 10.10), with about 50 gb of free space.

Solution 2.
I installed:

  1. VirtualBoxfrom the virtualbox website
  2. Downloading the Windows XP iso from IS&T
  3. Creating a new machine in VirtualBox with 1.4 gb of RAM and 20 gb of  (dynamically expanding) virtual hard drive space
    (my Ubuntu setup consumes 500+ mb of RAM)  
  4. Installed Solidworks the normal route (MIT MechE website / share folder)
    This step took, oh, half a day or so on my netbook.

Results: Runs okay, faster than all my friends expected. Haven't tested it on a really complicated assembly. At the speed at which XP boots on my netbook, followed by starting up Solidworks (~15 minutes total), I'm very grateful for the "pause" feature on VirtualBox (so I can boot everything up ahead of time), but the virtual machine still sits there eating 1.4 gb of RAM.
Verdict: Not a great solution.

(This is skipping a long story of trying to install a modified-to-be-slim 1gb XP, followed by hours spent trying to expand the virtual hard drive from 1 gb to 20 gb so that I could install SolidWorks. Many thanks to my friends at MITERS last Friday/Saturday).

Solution 3
Now, I also have a desktop, which allows me to reach a more ideal solution. Over IAP I installed Windows 7 in order to install Solidworks, bringing me to a triple boot of XP, Ubuntu, and Win7.
Desktop: 80 gb SATA drive, 3.6 ghz, 2 mb RAM. + a 50 gb IDE (aka PATA) drive I acquired.

In retrospect, I should have mounted the 50 gb drive and commanded XP to recognize it, thus giving me enough disk drive space to install Solidworks. (XP eats up less RAM than Win7). Oh well.

Anyway, there's a few options here.
1. VNC (Virtual Network Connection): TightVNC, UltraVNC, and RealVNC are free software for Windows. For connecting to a VNC server, Vinagre comes by default on Ubuntu.
2. RDC (Remote Desktop Connection): Comes by default on Windows. sudo apt-get install remmina for Ubuntu.

VNC: Allows both server (local user) and listener (remote user) to see the screen at the same time. Slow (literally transmitting images).
RDC: Fast. When listener (remote user) connects, locks out the server (the local user) so she can't see what's going on.


  1. Download and install TightVNC, set and remember passwords. Run it as a service (supposedly faster). Icon (with "V") should appear in status bar.
  2. Notes: I went with TightVNC, since it looked like it had been updated more recently (mid-2010) than UltraVNC, and I read mixed review of the free version of RealVNC.
    No idea about TightVNC vs. RealVNC vs. UltraVNC in terms of speed.
  3. On Ubuntu, run vinagre and set up a new VNC connection to your IP address
  4. Done!

  1. Enable remote access on win7 (Control Panel > System > Allow Remote Access)
  2. Disable hibernation / suspend power saving
    Also note that the IPs (via ethernet) change every few days, and you may hit a IP change like I did, so double-check via (or other method, such as the TightVNC status tray icon)
  3. Install Remmina on Ubuntu (sudo apt-get install remmina)
    Start Remmina
    Create new connection: Under basic, put RDC protocol, the IP address of my windows machine, my username and password on windows. Hit "Ok"
  4. Done!

The result: VNC showed noticeably lag both refreshing the screen and updating cursor position (half a second, perhaps) and it was funny watching the mouse cursor jerk around on my desktop. RDC ran like I was sitting at my desktop, even after bumping it up in remmina from 256 colors (the default, which looked very weird) to 16 bit colors.

VNC (lag)

RDC (almost negligible lag)

Verdict: RDC to a desktop is fastest. Run Solidworks on my desktop. It's acceptable to reboot into windows occasionally, especially if it's just for set times like lecture or lab. I wasn't happy about the idea of constantly running windows instead of Ubuntu on my desktop, which won't be the case.

Notes for myself

BIOS Settings: Turn all drives ON (PATA-1, PATA-2, SATA-1, SATA-2). Set Boot Order to SATA before IDE.
Ignore "Drive 1, 3 not found" warnings and hit F1 to continue.
Booting Windows 7: Connect all drives. At GRUB screen (installed with Ubuntu), select "Windows 7 (loader)" followed by "Windows 7" (the second time is only because I have an old UNetBootin installation).
~Win7 GRUB e: "root (hd0,1)"
Booting Ubuntu: Disconnect Win7 hard drive (otherwise, says "Error mounting")

I think I had to do some work to repair GRUB after installing Windows, but I don't remember exactly what. Google!

Wednesday, February 2, 2011

Embedded pdf in Firefox 3.6, Ubuntu 10.10, with Evince and Mozplugger

sudo apt-get install mozplugger

I think I had acroread installed (not sure, since it wasn't working), so I had to tweak mozplugger a bit to get it to work by adding a single line: repeat noisy swallow(evince) fill: evince "$file"

So my file looks like:
user@user-netbook:~$  sudo gedit /etc/mozpluggerrc

    text/x-pdf:pdf:PDF file
        repeat noisy swallow(evince) fill: evince "$file"
        repeat noisy fill exits: evince "$file"

        application/x-dvi:dvi:DVI file [...]

Restarted Firefox, works great.
(btw for troubleshooting: in my FF, under edit > preferences > applications > PDF Document, it says "Use MozPlugger 1.13.3 handler")