Ubuntu at the Edge of Technology

Press review 10-08-2013

The European Commission took this time of slow business to track back on its intentions to impose import duties on solar panels manufactured in China. There is an half victory to celebrate: a lower limit to price and a top limit on yearly capacity imported. But has I have been writing, a globalised marked is not really complacent with this sort of tactics. On the one hand China has surely waved retaliative measures, on the other hand manufactures can simply shift production to other countries. As technology progresses these limits may soon become outdated and force further negotiations; the struggle of centralised governance structures against decentralised power supply has just began.

Zinc-air electrical storage ready for grid testing

One of the technologies I have been following closer in recent times is metal air electricity storage. The principle seems simple enough: an aqueous solution (the electrolyte) containing metal particles (anode) that oxidate in contact with ambient air (cathode), thus releasing free electrons. Zinc-air batteries in particular have been in the market for long; cheap to produce and with high energy density, they are used in a myriad of applications. The only downside: once the metal in the solution has fully oxidated, the battery can at best end up in recycling.

Recently though there is an American company that has developed a rechargeable zinc-air battery design that promises to bring the electricity storage market up side down.

The limit to China's coal growth

Coal extraction in China is the epitome of unsustainability. It tripled from 2000 to 2010, with double digits growth rates in some years, as in 2011. Consumption is growing even faster, and although China being the largest world producer, it has been a net importer since 2009. Round numbers, half of the coal extracted in the world is consumed in China.

Naturally, none of this can go on forever. Last week an outstanding piece of journalism published by Bloomberg points to what may be the definitive limit to China's coal growth: water. Although not my usual mondus operandi, I think it deserves its own log for a deeper reflection.

Bloomberg
China Coal-Fired Economy Dying of Thirst as Mines Lack Water
Kevin Hamlin, 24-07-2013

Daliuta in Shaanxi province sits on top of the world’s biggest underground coal mine, which requires millions of liters of water a day for extracting, washing and processing the fuel. The town is the epicenter of a looming collision between China’s increasingly scarce supplies of water and its plan to power economic growth with coal.

Soft Machine - 1972 - Fifth

In the Rock music world there are recordings that have become landmarks; decades may pass over its original production but a consensus perdures on its exceptional qualities, even among those that may have born long after. In other cases the consensus does not exit, by one reason or another, an outstanding work can push the limits in such a way that it alienates part of the listeners spectrum. It is one of these records I would like to board today: Fifth by Soft Machine.

Soft Machine was on of the bands emerging in Canterbury in the late 1960s towards international recognition. They took a particular approach to Rock, embedding elements of Jazz, in what would become known as Jazz-Rock. In spite of being one of the unavoidable precursors of the genre, Soft Machine remained for a few years well ahead of its peers, avoiding any fall into stereotypes. These first few LPs evolved around the trio composed by Mike Rutledge (organ), Hugh Hopper (electric bass) and Robert Wyatt (drums), later with the important addition of Elton Dean (alto sax). This core line up featured in the first four LPs of the band, each time diving further into Jazz, composing what are today its most appreciated recordings.

Press review 27-07-2013

When I studied Economics at the University Demand and Supply where injective functions in the Cartesian Price vs. Quantity plane; the former with negative slope, the latter with positive. Now in Stanford University they seem to have found new Demand and Supply functions that are bijective, thus pretending to explain everything that went on in the oil market the past decade. They don't even try to clarify if the "peak" they refer to is relative to Quantity or Price, much less formalise the building of such awkward functions. Several media outlets picked up this piece of nonsense and diffused as if it was science; criticism is too much to asked from journalists these days.

Shared work in a SVN versioned folder with Linux

Here's a test case: two (or more) users work on a common project that is versioned through SVN. Each user has the project checked out on their own environment and regularly commits to the SVN repository. Now the project has to be deployed to a server, being checked out at a particular location where some of its assets are served from. Both users must be able to regularly log on to the server and update the contents of the project folder from the repository. The catch is that neither of the users have admin rights over the server. With the default file system permissions every time a user checkouts the project from the repository the files are re-writen and its permissions attributed to the user, blocking access from other users, and most importantly, from any services depending on these files.

This post presents a recipe for this issue based solely on basic file system permissions. In the end both users should be able to work on the project folder without blocking access to each other.