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What "extremely hot" means in Sweden

Last summer in Sweden 2014 we had like five days straight with temperatures around 28 celsius (82 fahrenheit) during the day. Such temperature is considered more or less extreme and during such circumstances things go bad for some of us frozen swedes. Yeah, you read correctly, that is extreme for many of us. You're laughing right? Come here when it's -5 celsius instead and see who has the last laugh ;) Alright, I'm exaggerating a little. bit Most people like temperatures as such. But I believe I found an exception here.

Most housings in Sweden don't feature a cooling system, which is reasonable. I mean, it would be sort of the same thing as opening a sand shop in the desert of Sahara. However, sometimes maybe there is a need for sand even in Sahara. Some fellow engineering student (I guess), suffering in his rented student housing in Gothenburg, found a remedy to his hardships. Down at the yard there was a storage room for solid waste were disposed fridges ocassionally could be found. To shield himself from this burning inferno he mounted the fridge in the window of the apartment. That's right, when there was 28 celsius in Sweden some guy mount a fridge in his, or perhaps her, window. If the top part of the opening of the window was covered for the system to actually work is unknown.

This however reminds me of a deeper aspect. There is so much useful material that just goes to waste in Sweden, while it could sometimes be directly recycled, like here. Okey, this is not a great example, I don't expect people to mount old fridges in their windows. But a lot other stuff that is thrown away is fully usable.


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[VAWT] Affordable wind measurements

The shop Clas Ohlsson in Sweden sells a spare anemometer for the  WH-1080 weather station for a hobbyist friendly price around 15 euros. This anemometer can probably be found in other countries too.

The WH-1080 spare anemometer

Here  you can read about how to use this anemometer together with an Arduino or any other embedded system.  As we couldn't find any data on the characteristics of this sensor, we did our own calibration in a wind tunnel and the results are presented in the report above. This anemometer was used in a Bachelors Thesis project related to the devlopment of optimization of the Savonius Turbine, here tagged [VAWT].

[VAWT] Plausible improvements of the Savonius windmill

Cut a barrel in half, mount it on a shaft and you have a windturbine. If the barrel is used, then what else probably would end up on a scrap heap is instead used for converting renewable energy.

Simplicity and low cost makes this an attractive option especially for societies with limited economy and a malfunctioning or non existing electric grid. Small off-grid electrical networks can be built and people who perhaps most needs electricity get that. Isn't that neat?

Savonius (from

An overlooked potential?
The Savonius though has a widespread reputation of having low effiency and is often dismissed as a credible option around forums and in formal litterature. However, when looking at the graph below from a publication Wortman did 1983, the effiency can be realtively high provided that the TSR(Tip-to-Wind-Speed-Ratio) is held at a correct value and the windmill should work quite nicely. In practice this could probably be done by controlling the generato…

[RR] Automated rescue boat

We have a project course at our  master program System, Control and Mechatronics, were we could apply to one of around 30 projects available. I was really happy that I got my first choice, which is a project carried out as a joint effort between SSRS (Swedish Sea Rescue Society) and Chalmers. The goal is to develop  autonomous or/and semi-autonomous vehicles that can help out in rescue missions. The current vehicle, a large water scooter named Rescue Runner, is able to follow a larger leader boat.

However, the people involved want some better tracking capabilities and stability of the control system. We are currently a team of three persons hoping to achieve this. Stay tuned, more information will be posted when we finish. Or well, not if we sink though. Then I'll try to cover it up, and hope for dedicated readers to spam me with comments ;)

Here you can read some in Swedish about the project: