The Coupon (Sticker) Collector

Supermarket chain Edeka currently runs this sticker collecting racket – which used to be smurf collecting – where you get four stickers with animal pictures for every €10 spent. The kids are collecting like crazy, I am told, even though the pictures are mediocre at best. Anyway, as geeks we don’t care much about the […]


Summer of Code

Dabbling in JavaScript has been my new pasttime for the last few weeks. After a lot of poking in the dark trying to customize my TiddlyWiki, I thought that I could use my newfound JavaScript powers to make more useful stuff. So I sat down and wrote a bunch of scripts that add features to […]


shopping for a NAS

So I have this internal 500GB HDD drive that holds the backup for my personal data and photos and whatnot. Not only is it 98 percent full, but also very noisy, even when spinning idly. Since some Windows process always seems to access it regularly, it also never spins down. To get some peace of […]


the Doppler effect (relativistic)

Christian Doppler in 1942 predicted the Doppler effect for all kinds of waves, not only sound waves. The Doppler effect for light was demonstrated in 1948 by Fizeau. In conjunction with the article on the classical Doppler effect, as it occurs e.g. for sound waves, we will here examine the relativistic Doppler effect which is […]


the Doppler effect (classical)

The Doppler effect is nothing really new. It’s well-known that Doppler frequency shift occurs for sound as well as light; there are, however, some subtle differences between the two, owing mainly to Einstein’s special theory of relativity. This article describes the classical Doppler effect as it occurs e.g. for sound waves and in which the […]


TiddlyWiki – incoming Links

There are situations when you need to have a list of all the tiddlers that link to some other tiddlers in your TiddlyWiki, e.g. when renaming that other tiddler and having to update all the references to it. Some plugins out there give such lists,…


Basics of Doppler Vibrometry

This post has been overdue for quite a while now. I originally intended to post something about what I do at work soon after I started my new job. That was more than a year ago; time really does fly. Somehow there was always something else already in the pipeline and I never got around […]


O’ahu, Hawai’i

Final stop: O’ahu. Waikiki is just a tourist trap, but fortunately O’ahu has more to offer than crowded beaches, shops and Asian food. Here’s proof:


Maui, Hawai’i

After a week on the Big Island, we headed over to Maui. Here are some panoramic highlights…  


my favorite focal lengths

I have been meaning to something like this for quite a while, plotting the distribution of the focal lengths used in the pictures I shoot, to see which portions of the zoom range get the most action. Here is the graph for our recent vacation on Hawai’i, obtained using the Lightroom 4 beta and Jeffrey […]