ummels.de

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Winterwanderung zur Gemmi

Wie der Zufall so spielt, stand ich im März 2022 vor der Herausforderung eine der mehrmals pro Jahr bei COOP angebotenen Spartageskarten für die Schweiz in den Händen zu halten ohne einen Plan zu haben, wohin es gehen könnte.

Neustart auf Deutsch

Nach fünf Jahren ein neuer Blogpost? Und auch noch auf Deutsch? Ihr fragt Euch sicher warum? Wie Follower*innen meines Twitter-Accounts wissen, habe ich in den letzten Jahren hauptsächlich dort meine Reisen dokumentiert.

Autumn in Graubünden

It’s that time of the year when the trees show their nicest colours. What better time to visit the most Eastern part of Switzerland, the Canton of Graubünden (Grisons) and its narrow-gauge railway network operated by the Rhaetian Railway (RhB)?

Secure Hosting with GitLab Pages and Let's Encrypt

Update: GitLab has fully integrated Let’s Encrypt with GitLab Pages, so it’s now easier than ever to serve your website from GitLab Pages via HTTPS. The procedure described below is therefore outdated.

Going Static

After almost 10 years, I have decided to ditch Wordpress for Jekyll, a static blog engine. As opposed to Wordpress, Jekyll is not dependent on MySQL and PHP, but simply generates static HTML files from sources in Markdown, so you can create your blog posts comfortably using your favourite text editor, let Jekyll generate the HTML and put it on an arbitrary web server.

Tramino Braunschweig

After some delays due to certification, the new Tramino trams for Braunschweig have finally entered into service last Monday. The first two pictures show unit 1451 running on line M5.

Taking the Slow Train Through the Harz Mountains

Not far away from Braunschweig in the Eastern part of the Harz Mountains lies a large narrow-gauge railway network where steam engines still operate on most services. In order to tour almost the entire network, my colleague and I started our tour in Quedlinburg, which is easily reached by a regional train from Magdeburg.

Dijkstra in Scala

Dijkstra’s algorithm is a fundamental graph algorithm, which allows to compute the shortest path from a source node to a target node in a directed, weighted graph, i.e. the path with the smallest accumulated weight.

Priority Maps in Scala

In many algorithms—including Dijkstra’s algorithm for finding the shortest path between two vertices in a weighted graph—we need access to a data structure that maps elements to numbers or priorities where we can efficiently obtain and remove the element(s) with the least priority and add new elements as the algorithm progresses.

Dawn in Brunswick

This tram has just left the depot to make its first run as line M5 to Hauptbahnhof. Due to construction work at Leonhardplatz the direct route to the terminal is blocked and all trams need to go via Schloss, which made this picture possible.