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 […]