The embedded controller
In part 1, we looked at the communication between a Lenovo Thinkpad X230T laptop and battery, and discovered that there a challenge-response protocol used to authenticate ‘genuine’ Lenovo batteries. On the laptop side, this – and battery communication in general – is implemented in a component known as the embedded controller (EC). Continue reading
Two months ago, I bought a new battery for my Lenovo laptop (a ThinkPad X230T). I was about to go away on holidays and wanted a battery that could last me through a plane flight; the original battery was by then barely lasting ten minutes. Little did I know that I was about to be in for an adventure. Continue reading
These are some slide decks I used to use when I ran introductory courses for the UNSW Photography Club. They are a pretty good set of slides so I figured they should have a home on the Web.
Part I: Camera Principles (focal length, ISO speed, shutter speed, aperture, etc.)
Part II: Metering/White Balance
Bonus slide deck: Lighting and Studio Photography
I went to a great lecture today by Professor Chris Barrett on “The Global Food Security Challenge in the Coming Decades”. The slides from this lecture are available here. Here are my notes:
- Current global food demand growth is ~1.25% pa, while annual growth in supply has been falling and is now only ~1% pa.
- This means food prices are now rising (after decades of falling food prices). 2011 was a record profit year for US farmers. This is good news for renewed investment in the agricultural sector, but until supply can be increased, the poorest will suffer.
- Developing countries have by far the largest effect on food demand. Not only are they growing much faster than developed countries, but a much larger proportion of income increases are spent on food.
- Currently 85-90% of food is consumed in the country it is produced. However, most arable land in Asia is already used, so rising Asian demand will require large increases in productivity per hectare or large-scale food imports.
- The remaining unutilised arable land in the world is mostly in Sub-Saharan Africa and Latin America. Huge land grabs by foreign investors are occurring as a result. In many corrupt countries, the proceeds are going to the political classes, while the poor get dispossessed (even in those countries with property rights, many poor are not within the land title system). A 2008 Daewoo deal to lease 1.3 million hectares in Madagascar contributed to the overthrow of the government there.
- Nutrient deficiencies in the developing world are more severe than energy deficiencies (~15% of population in developing countries are deficient in energy, 31% in Vitamin A, 33% in iodine, 61% in iron). Effects of nutrient deficiencies on intellectual development constitute a poverty trap.
- Governments everywhere need to invest more in research on productivity-increasing sustainable farming methods, which may or may not include GMOs, to avoid excessive monopolisation of agricultural technology vital to food security. Patent reform may be required.
One of the simplest solutions for sending measurement instruments up into the stratosphere is a rubber balloon filled with hydrogen or helium. While the physics of such a balloon would seem to be simple, there are actually some interesting considerations.
Welcome to the newly redesigned zmatt.net. I seem to only get around to upgrading my personal website once every decade so this is a special day indeed. The biggest change is that I now have a blog here (powered by WordPress). I used to blog on LiveJournal but I was seduced by short attention span media like Facebook, I’m trying to restart the blogging habit.
* 30% more Web 2.0 not guaranteed