Hi, I am Martin Ueding, a physicist (M.Sc.), programmer and PhD student in Lattice QCD. My dissertation is handed in, I am currently awaiting the defense.

Although I am German, most of the content on this website is in English as both science and programming is communicated mostly in English.

Since 2011, I study Physics at Bonn university. I have finished my Bachelor degree in 2014 and my Master thesis in 2017. My dissertation was finished in 2020. See the studies section for the study related material.

At the age of 13 I started programming with C. Then I looked into HTML and CSS, started to use PHP and then MySQL. Looking for something to write software with a nice user interface with, I came to Java. Then I looked into more languages like Bash, Python, JavaScript, GNU Octave, VimScript, Fish. From then on, I tried to do most things in either Python 3 or C++11, so that I only have two languages, which I know well. For my work I now use R and also picked up the Wolfram Language. See my portfolio.

My most popular project are the thinkpad-scripts which I wrote to get all the screen and digitizer features working effortlessly on my ThinkPad. It is a collection of Python modules that take care of docking and screen rotation.

For several years now, I have been almost paperless. The main challenges are papers I get from other people and hand written notes. The former can be faced with a scanner, the latter was more interesting. I own a Wacom Tablet since long before I started to become paperless, but I never had a good software for note taking. Since I did not find one at first, I wrote jscribbe. After I was almost done with that, I discovered Xournal which I now use most of the time.

You can also find me on other platforms:

# Two-Stroke Engines

Two-stroke engines seem to be in a lot of places in Germany: scooters as well as leaf blowers, lawn mowers, hedge trimmers, lawn edge trimmers and chainsaws. In all cases the advantage of the engine is that it is rather light and cheap to produce.

But these savings are paid externally. Only using two strokes means that oil is burned in the process, leading to really nasty exhaust fumes. Also these devices do not have an exhaust cleaning system to save weight. Lastly they also don't have a muffle system, so they are obnoxiously loud. All of this is understandable, but alternatives with electric engines are available for quite some time.

While I was in China for four weeks in 2019, I only saw two scooters with a combustion engine. All others had an electric engine. The battery pack could be taken out and looked standardized. I imagine that it was similar to a car battery and the owners would just charge it in their appartment. According to other people who visited China, these have been around since at least 2010.

# Kdenlive Crash on Fedora

I have made a little video from footage that I captured. Also I added some voice-over audio recording. For creating the video I use Kdenlive on Linux. This is my project:

In order to export this to Twitter, I need to export the project. So I open the export dialog and just select one of the default formats.

# Erwartungswerte von Bußgeldern

Die StVO-Novelle von April 2020 hat diverse Bußgelder erhöht, außerdem sind diverse Dinge verschärft worden. Auch außerhalb vom Verkehr gibt es diverse Stellen, an denen die Strafen höher sind als vorher. Generell ist die Idee, dass höhere Strafen zu Abschreckung führen. Ich habe aber den Eindruck, dass das gerade im Straßenverkehr einfach nicht richtig funktioniert.

Letztlich macht jeder folgende Abwägung: $$E(\text{Strafe}) = \text{Bußgeld} \cdot P(\text{Kontrolle}) \,.$$ Der Erwartungswert der Strafe ist das jeweilige Bußgeld multipliziert mit der Kontrolle, dass man erwischt wird. Wenn die Wahrscheinlichkeit erwischt zu werden relativ hoch ist (wie bei Mord), dann ist die Erwartung der Strafe fast so hoch wie die vorgesehene Strafe bei Verurteilung. Man überlegt sich das dann also sehr genau. Wenn das Bußgeld vollkommend vernichtend wäre, dann ist die Kontrolldichte fast egal, man will es nicht riskieren.

# Why Write A Short Text When One Can Make A Long Video Instead?

I really hate video tutorials. There are very few which are well made and concise. Most of them have a very low information density. Also with the video format one cannot just skim it like one can with a text. I much prefer text with pictures. Also I prefer papers over talks as I can access them with in the way that I like best.

This particular time I had a video where I wanted to obscure some regions. You know this effect from TV shows where they pixelate some face or company logo. The problem is that the object moves on the screen and therefore the pixelated area needs to track the object. This can either be done by hand or automatically.

Using my video editing program of choice, Kdenlive, I have tried this. Quickly I realized that I needed some tutorial. There is a bit in the official documentation about “auto mask”. There is not a lot of explanation, rather just a video. In that video the author shows how automatic tracking works. One basically just selects a region and let the thing do some work. It just did not work out for me so well.

Therefore I wanted something with keyframes, where I can manually adjust the box every few seconds. I let Google search for “kdenlive pixelate” and found only video tutorials. So I took a look into the first one, “Kdenlive Lesson 20 - Blur and Obscure”. The author spends the first minutes to talk about sub-clip selection, which I already knew and shouldn't be the topic. Then he shows how one can pixelate a fixed section of the screen, which does not help me. And only after spending four minutes I heard him say that there is a way to track stuff on screen, but he does not know and is going to look into at some future time. Five minutes wasted.

# Selling Mortgages as Retirement Funds

If you have a finance background, you may call this obvious and call me naive for realizing so late. But maybe you also did not know before. There are a couple of naive assumptions I had about money, and bringing them all together formed quite an abyss to look into. There are three parts to it.

First part: I assumed that all money would be backed by the central bank. So a local bank could not invent money. They would have to have people bring in their hard-earned cash and put it into a (say 10 year) fixed-term deposit. Then other people would request a mortgage and the bank would take a portion of the savings money and lend it to these other people. This scheme only works because the fixed-term deposit cannot be accessed in that time. The lender pays a large interest, the bank pays a small interest to the saver and keep the difference itself. From this difference they would pay the salaries of employees and take the risk of default (people not paying).

The reality is that local banks just invent their own book money and only like 10 % of the money needs to exist for real (as central bank backed money). So the amount of credit that a bank can give to customers is not limited by the amount of money that people have in their fixed-term saving accounts, but it is a large multiple of all money, even including checking accounts. This means that the bank would break if only a fraction of the people would cash out. Additionally there is money from investors into the bank, so the saving accounts may be only a small fraction of the real money that the bank holds. For investment banks there might even be no saving accounts at all.

# CO₂ Footprint of my PhD Thesis

As part of my Master and PhD theses I have used a lot of computer time on supercomputers in Jülich, Stuttgart, Bologna and the cluster in Bonn. I want to estimate the magnitude of CO₂ that this has released.

It is a bit hard to say how many core hours I have used exactly as I have already used data that existed already. Let's take like 5 Mh to pick a number. Then on JUWELS with the dual Intel Xeon Platinum 8168 with 48 cores that is around 100 kh. Each of the CPUs has a TDP of 205 W. Then there is network, file system, backup. Perhaps 750 W per node? And then there is cooling, which roughly takes the same on top, so 1.5 kW per node. That makes 150 MWh of electricity used. In Germany it seems that we would have to take 0.4 kg/kWh of CO₂. This would then give a little over 60 t of CO₂.

# SpiderOak One Performance Issues

As I wrote earlier, I have been using the SpiderOak One Backup service for a while now. It costs more than the usage of Duplicity with Backblaze B2, but it promises to work better. Also it creates backups continiously, so I don't have to wait for the full hour to have a backup. Using inotify it will automatically put files into the queue just as I save them. I really like this. My laptop could burst in flames and I would only lose a few minutes of work.

But the performance of the system is bad, again and again. I recall that I tried the service a few years ago and had just exactly the same issues with it. Often it would not utilize my upload bandwith (10 Mbit/s) fully but rather utilize one full CPU core, which seems excessive. I would restart the application and then it would stop this. Often this is triggered by using the GUI. I have the feeling that the GUI cannot really cope with ten thousand of files being listed, so it just freezes up as it tries to display it all.

Lately even restarting did not help. So I wrote to the support on 2020-05-23 about this issue. I got a reply telling me to move the ~/.config/SpiderOakONE directory somewhere else and sign back into the program. Then it would do the syndication again and it should work fine. At the time it seemed to work fine again after a few simple restarts, so I did not follow through on this at that time.

# Gehweg mit »Fahrrad frei« – Nichts Halbes, Nichts Ganzes

Wie schon im Artikel zu Schutzstreifen beschrieben gibt es Radwege (baulich getrennt), Radstreifen (durchgezogene Linie auf der Fahrbahn) und Schutzstreifen (gestrichelte Linie auf der Fahrbahn). Diese Flächen haben Radfahrer exklusiv, auch wenn das wegen Fehlverhalten häufig nicht so gut funktioniert. Radwege und Radstreifen sind auch benutzungspflichtig. Dann gibt es auch noch Gehwege, die für Radfahrer freigegeben werden. Hier sind die Radfahrer zu Gast und müssen Rücksicht auf die Fußgänger nehmen.

Einen typischen Vertreter dieser Gattung hatte ich in Lülsdorf bei Bonn. Man mag auf den ersten Blick denken, dass die linke Seite des Hochboards ein echter Radweg ist, die linke Seite ein echter Gehweg. Jedoch ist der linke Teil zu schmal um formal den Ansprüchen an einen Radweg zu genügen. Und was hat die Stadt dann gemacht? Offensichtlich den nicht verbreitert, sondern einfach die Beschilderung zurückgestuft.

Dahin wird man über eine Ampel geführt, die jedoch in der Streuscheibe das Sinnbild für Fahrrad enthält. Somit werden Radfahrer über diese Ampel geführt und erwarten auf der anderen Seite auch mit dem Fahrrad fahren zu können. Das stimmt schon, aber es ist eben kein Radweg.

# Stellenanzeige ohne Ortsangabe

Ich suche nach Jobs in Bonn und näherer Umgebung. Also habe ich auf Indeed einen entsprechenden Filter:

Das scheint aber nicht sinnvoll zu funktionieren. Ich bekomme dann so tolle Angebote wie dieses hier:

Da ist also in den Metadaten der Ort mit NRW angegeben. Technisch gesehen ist NRW auch im Umkreis von Bonn verfügbar. Nur Essen liegt da halt nicht. Und so geht es dann weiter mit diversen Stellenanzeigen, deren Ort sogar einfach nur falsch ist:

# Kommentar zu Streitgespräch im General-Anzeiger-Bonn

Im General-Anzeiger-Bonn ist heute der Artikel »Sperrung oder Durchfahrt: Was ist besser für die Bonner Innenstadt?« erschienen. Dort streiten sich der Vorsitzende des Einzelhandelsverbandes, Jannis Vassiliou, und die Bonner ADFC-Vorsitzende Annette Quaedvlieg über die Wiedereröffnung des Bonner City-Rings. Wenig überraschend ist der Einzelhändler für eine Wiedereröffnung. Die Argumente sind aber haarsträubend, das möchte ich gerne einmal kommentieren.

Herr Vassiliou eröffnet nach der Frage zur Bedrohung der Innenstadt durch einen gekappten City-Rings hiermit:

Die Bonner Innenstadt hat eine wunderbare Fußgängerzone, eine echte Errungenschaft.

Also ein Bereich, in dem keine Autos fahren, ist eine echte Errungenschaft. Mit dem Auto direkt vor das Geschäft zu fahren, ist schlecht. Es ist besser, wenn man mit dem Auto nur außerhalb sein darf und zu Fuß in der Stadt unterwegs ist. Okay, merken wir uns.

Das ganze bekräftigt er dann weiter:

Der Gedanke, in jedes Parkhaus hereinzukommen und sich innerhalb der Fußgängerzone zu Fuß zu bewegen, ist richtig, damit Käufer in die Stadt hereinkommen können.

Und ihm scheint es auch undenkbar dies zu ändern. Er meint natürlich den Teil mit den Parkhäusern. Die Autofahrer sollen also direkt an den Rand der Zone fahren dürfen. Da soll bloß kein Fußweg außerhalb des autofreien Bereichs erforderlich sein. Das ist schon ziemlich bizarr. Autofahrern kann man also nicht zumuten, dass sie sich in der Nähe von Autos und Autoverkehr aufhalten müssen. Anscheinend ist Autoverkehr nicht zuträglich für die Aufenthaltsqualität.