Saturday, April 27, 2013



Two weeks ago, Switzerland started its new international tourism campaign, projecting a quaint image invented by Romantic writers like Friedrich Schiller and Johanna Spyri, with a few chaps from the Outback fighting in a Schwingen match. This suits well with the political majority party, who would like to place a cheese cloche over the country so it can live in a bubble.

Meanwhile, the Swiss fret over the 2050 energy package, ratified 25 May 2011, after Fukushima and the decision to exit nuclear energy generation. The slogan is that of the 2000-Watt Society, in which each person does not use more than 2000 W per day (today's average is 6000 W) and emits less than 1 Ton of CO2 per annum.

Such goals require the thought leadership of visionaries and effective demonstrators. Solar Impulse has been one of the best demonstrators. For example, in May 2012 it flew from Payerne across the Mediterranean to Rabat and Quarzazate, convincing the Moroccans that solar energy is the way of the future, supporting the plan by King Mohammed VI to construct the world’s largest thermo-solar power plant in Ouarzazate.

The visionaries behind Solar Impulse are Bertrand Piccard and André Borschberg, along with their sponsors and their big team.

Bertrand Piccard and André Borschberg

The numbers of Solar Impulse are quite impressive: with a wingspan of 63.40 m it is the size of an Airbus A340 or a 747, but it weighs only 1,600 Kg, just a little more than a Prius. Its range is infinite, because it can fly perpetually, since it produces much more electricity than it consumes, just as the Swiss hope to do with their houses.

Currently Solar Impulse is in Hangar 2 at Moffett Federal Airfield at Ames Research Center, getting ready for the next mission.

Admirers of Solar Impulse in Hangar 2

Solar Impulse in Hangar 2

Although the airplane can fly perpetually, in their 2015 flight around the world with the second model, license HB-SIB, Bertrand Piccard and André Borschberg will take turns every 5 days, because that is how long a trained human can stay awake and pilot, and also sit with very limited motion on the pilot seat/toilet combo:

Solar Impulse cockpit

On the first of May, Bertrand Piccard and André Borschberg will take off from Moffett Field at a speed of 44 km/h and fly their Across America mission, which will take them to Phoenix, Dallas, Saint Louis or Atlanta, Washington D.C., and finally JFK in New York City.

If you happen to look up and see a jumbo with license HB-SIA soaring silently at a speed of 70 km/h, think what you can do to give back more energy than you consume, so your total usage (think at those servers farms delivering your contents) is below 2000 W per day. In the case of the Solar Impulse, its 11,628 SunPower solar cells have an efficiency of 23% and drive the four brushless sensorless electric engines in addition of charging the batteries for when there is no sunlight.

Tuesday, April 16, 2013

Monday, April 15, 2013

Alpine Internet Speeds

The Swiss Federal Office of Communications has published a map of telecommunications in Switzerland. The map can show television availability, upload and download speeds, connection types, and the number of providers, all at a resolution of 250 meters. The publication also provides a guide to broadband expansion projects taking place in Switzerland. The goal of the publication is to help plan broadband access projects and to help users make smart decisions regarding telecommunications.

Link to the tool: broadband map (in German, French and Italian)

Scaling body size fluctuation

Flocks of birds, schools of fish, and groups of any other living organisms might have a mathematical function in common. Studying aquatic microorganisms, Andrea Giometto, a researcher EPFL and Eawag, showed that for each species he studied, body sizes were distributed according to the same mathematical expression, where the only unknown is the average size of the species in an ecosystem.

Taken together, these observations of size distributions within a species and within all the species in a given ecological community have interesting implications. If in an ecosystem several species begin to converge around the same size, a balancing force will kick in to restore the power-law distribution, either by acting on the abundance or size of each species.

Finding power-laws and using them to describe complex systems already has a successful track record. “In physics, the observation that systems followed power-laws was instrumental in understanding phase transitions. We believe that power-laws can be similarly helpful to gain a deeper understanding of how systems of living matter work,” says Giometto, a physicist, who is seeking to apply methods from his field to understand biological ecosystems.

Link to the paper: Scaling body size fluctuations

Sunday, April 7, 2013

Where is the sun?

When we take architectural pictures, we want to have the sun shining from the side, because this accentuates the edges. In the old days, this meant a shoot took two days, one to visit the sites of the buildings of interest to determine the best time, and a second day to do the actual shoots in a tour taking us to each building at the best time.

Today this is much easier. We can use an online tool like SunCalc to determine the best time.

In the box at the top left you enter the shoot location, then on the horizontal time scale you simply drag the orange dot. On the map, the thick orange segment indicates the sunlight direction. Just move the orange dot on the slider until the segment hits the façade more or less perpendicularly. You can enter the data into a spreadsheet, which you sort by the time, to get your itinerary.

By they way, the thin orange curve is the current sun trajectory, and the yellow area around is the variation of sun trajectories during the year. The closer a point is to the center, the higher is the sun above the horizon. The colors on the time slider above show sunlight coverage during the day.