blackblog.

snippets of blackwings life

exams done – some scientific literature suggestions!

Man, after 4 years its done – No more exams left to get the university diploma in chemical engineering! Just the internship and diploma thesis is open :)
So lets summarize. I just finished my 8th semester with the last three (oral) exams namely in “Membrane Separation Technology“, “Thermal Seperation Processes II” and “Solvent Concepts for Catalytic Processes“. It turned out that finding books to dig into those subjects are pretty hard to find. So here is my suggestion what books & papers might be helpful to get a broad overview:

Membrane Seperation Processes (Prof. König):

Solvent Concepts for Catalytic Processes (Prof. Wasserscheid):

Thermal Seperation Processes II (Prof. Arlt):

Most of these articles are reviews on this specific topic. They had been selected by just searching by Google Scholar. During my thesis (topic was: Measurement of partition coefficients of drug-like-solutes in micellar systems by ultrafiltration) this spring / summer it turned out to be way more useful than the (expensive) SciFinder. Especially the BiBTeX Export functionality really kicks ass (Just activate it by Scholar-Preferences)!

crypto raid

In the last days I finally converted my fileserver at home to the dm-crypt / LUKS infrastructure of the Linux-Kernel in order to replace the old crypto-loop infrastructure which was running for some time.
I also used this to cleanup my bitbucket and enlarge my md-raid5.

Actually I was quite impressed by the speed when I set-up a the md5 raid and added the LUKS container using blowfish-cbc-essiv:sha256 and started to copy my data to this… On my old Athlon 1000 I got about 15mb/s writing performance, which is quite impressing!

Some thoughts on Latte Macchiato

lattemacchiato As you might probably know, I really developed a faible for coffee during the last few years, grinding the beans myself and celebrating the brewing-procedure… I prefer coffee beans of coffeemamas (Berlin). They provide excellent beans of different origins – But thats not the topic. Inspired by some magazines article, I spent some time to think of the process-engineers view of coffee. Maybe the knowledge I got at university, especially chemical thermodynamics and heat- and masstransport, is really good for some real-life topic. So here are my toughts:

  • As clearly seen, the Latte Macchiato develops three seperate phases: Milk froth, coffee and milk. Obviously, this is caused by different density. But wait, milk should be on top of the coffee, cause it has more fat. But the reason that milk is the densest phase is simple: coffee is hotter and so gets a smaller density. Froth of course has the smallest density cause of all the air…
  • Ever thought about this waving boundary layer between milk and coffee? Gravity is the reason why this waving is going to stop, cause engertically, a flat interface area is better than a waving one. The boundary layer itself is there, cause of the density difference.
  • When a Latte Macchiato is served, the boundary layer is clearly to be seen, but when you wait some minutes, it gets to a color gradient and finally the whole glas is a brownish coffee-milk-mixture… My first thought was: Diffusion. Thermodynamically the entropy of the system wants to be maximal – so all the components want to mix equally. But actually diffusion is quite slow. As I said before, milk is cooler than the coffee – So the real reason seems to be convective mixing.
  • It gets way more interesting, when you add some sugar to the milk-coffee system and use a spoon to mix it up: The turbulence causes the system to equally mix within parts of a second. But then, this nice interface area is destroyed… So mix the sugar into the coffee before adding it to the milk!
  • Preparing the perfect milk froth depends on many parameters. My strategy is to heat up the milk to about 60°C and use a rotating milk-froth-maker (Milchschäumer). By surfing the net, I actually found a research paper on the “Macroscopic and microscopic structure of milk foam“, which gave me many new hints, to optimze my strategy :) So if you are interested in everything scientific in milk froth – read this PhD Thesis. It opens a whole new world!

There are way more aspects to look at (like the *ding* sound the spoon gives, when it hits the glass or all the extraction related things of coffee making…), but maybe I will look at those some other day :)

pornophonique @ mrmcd101b

Pornophonique-xxlAs I wrote in the previous post, this weekend I decided to go to Darmstadt to enjoy the Metarheinmainchaosdays. So this weekend was relaxing with some party. The highlight definitively was the saturday-party-act “Pornophonique“: One guy using a guitar and singing and a guy using a Gameboy, yes, a Gameboy. They really did a great performance!
I also liked fx’ talk to application exploitation strategies talk and the x.25 talk of nobody a lot, but the WAN IGP protocol was not very satisfying for me. The (stand-up comedy) powerpoint karaoke was very entertaining…

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catch the train to darmstadt.

Today I decided to get to the Metarheinmainchaosdays. I have no car, so I had no other choice than using train.
After the odyssee two weeks ago taking me 7.5h instead of 4h, I was not really motivated for an 3h train-ride from Erlangen to Darmstadt…
I was supposed to take some regional train to Nuremberg, then an Intercity train to Aschaffenburg and finally a regional train to Darmstadt – so this was the plan.

The part from Erlangen to Nuremberg was quite easy – The regional train was on time. But, when I arrived, the “fun” begun again: I suddenly heard a nice voice telling me: “The IC to Dortmund is delayed due to police investigations. Please take the ICE to Wuerzburg instead.”. So I did – and was just 5 minutes late compared to the supposed arrival time in Wuerzburg.
In Wuerzburg, there was an replacement-train, having 1st class cars only. Ok, thats a positive part. But this train did not leave instantly after all passengers had changed…Reason: There was no personel. Hm. perfect. Replacement train, but noone to drive it. Hooray.
It took altogether another 45 minutes of waiting before we left Wuerzburg. And: The train was crowded. This is also quite logical: The regular IC is crowded. But an IC having just 1st class seats… And of course LESS than regular, then its obvious, that more people are standing than seating.
Like always: Nice idea (replacement train) but poor implementation.

So the next question for me was: Will I catch my connecting train in Aschaffenburg? The obvious answer is (of course): NO.
The train did not even stop in Aschaffenburg… It stopped at some place called Kleinostheim. The train assistant urged the passengers willing to go to Aschaffenburg to catch a Regional train there.
But I decided to go to Frankfurt. And there I got a connecting IC. This finally got me to Darmstadt. It just took me 4.5h…

Conclusion: I will get a car again. Using Deutsche Bahn just sucks. I’m sick of this after 3 years. I’m always late, it costs a whole bunch of money and even alone its now cheaper to go by car.

Finally a comparison of the trip to my parents (using Bahncard50 which is 100 euro/year):
2002: 20euro, takes minimum 3h35min
2006: 31euro, takes minimum 4h35min
+50% in 4 years. People, this sucks.

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