System Dynamics diagrams with Inkscape

One of the great things about System Dynamics software, such as VenSim, is the GUI, which allows you to see your model and all its connections as you are constructing it. However, the PLE version of VenSim is limited and one possibility is to write one’s own SD code with custom features. This is also a fun programming exercise. Initially I am willing to sacrifice real-time visual feedback in return for flexibility, but when I later want to visualize my model I would like some graphical output....

April 25, 2014 · Simon

Arsene Wenger unit conversion fail

“If six points is a ‘million miles away’, I don’t know what the translation of a mile into a point is.” – Arsene Wenger According to reports, Arsene Wenger is not great at simple mathematics. He was quoted today responding to criticism by Paul Scholes that Arsenal were “a million miles away” from winning the Premier League. Wenger said in response “If six points is a ‘million miles away’, I don’t know what the translation of a mile into a point is....

March 28, 2014 · Simon

Paper “Micromagnetics of shape anisotropy based permanent magnets” accepted for Journal of Magnetism and Magnetic Materials (JMMM)

Our new paper titled “Micromagnetics of shape anisotropy based permanent magnets” has been accepted for publication in Journal of Magnetism and Magnetic Materials (JMMM). Short description Visualizations of the computed magnetization data during reversal of soft prolate spheroids for aspect ratios (a) 1.95 and (b) 15.6, showing the different reversal modes. Permanent magnets are important components in electrical generators and motors, among other technologies, and they are critical to the operation of wind turbines and electric/hybrid cars....

March 26, 2014 · Simon

Reading scientific papers on Kindle with k2pdfopt

I have been waiting for some time for a new large-format eReader to be announced for reading PDF journal articles and textbooks. The Onyx Boox m96 sounds promising although the screen is “only” 10 inches in size and 13.3 inch eReaders for a reasonable price might be on the horizon. The exciting Sony DPT-S1 is unavailable, expensive and only works with PDFs. What a catastrophe! Come on, Sony! In the meantime, I have discovered an open source project called k2pdfopt that purports to convert journal articles into Kindle-formatted pages, by splitting the pages into smaller pieces and trimming borders etc....

March 24, 2014 · Simon

Cool Code Wall goes online

Our famous Cool Code Wall has gone online! Use the following code snippets at your own risk, and please suggest additions in the comments section (if it’s working).

March 18, 2014 · Simon

Reading an OpenOffice spreadsheet into Python

Sometimes the best way to manage simulation output data is in a spreadsheet. Or the data you want to use is already in a spreadsheet. Before reading it into Python for numerical analysis or plotting, or reading into xmgrace to plot, etc, it is normal to export the spreadsheet to a CSV or tab-separated file. But then you have two files. And if you do something in the spreadsheet you have to export it again and this is inefficient....

February 28, 2014 · Simon

LaTeX overfull hbox errors (and how I fixed mine)

If you have ever written a journal article or thesis using LaTeX then you probably came across lots of errors and warnings in the process. Those warnings can usually be ignored as they don’t stop the document from compiling, and many of us who just want to cross the finishing line probably never investigate what was causing them. One such common warning is the Overfull or Underfull /hbox message. These usually occur through no fault of the author, but because LaTeX doesn’t know how to hy-ph-enate certain words....

February 17, 2014 · Simon

New paper: “Micromagnetics of shape anisotropy based permanent magnets”

New paper I am pleased to announce our new paper, which can be downloaded from Abstract In the search for rare-earth free permanent magnets, various ideas related to shape anisotropy are being pursued. In this work we assess the limits of shape contributions to the reversal stability using micromagnetic simulations. In a first series of tests we altered the aspect ratio of single phase prolate spheroids, ranging from 1 (sphere) to 20....

January 13, 2014 · Simon

European Researcher’s Night

Photos from our European Researcher’s Night can now be found at UPDATE: The above URLs are now dead.

January 13, 2014 · Simon

Salome reordering during scripted Explode function

When writing Salome scripts that include a step to explode objects to their sub-shapes (using ExtractShapes) it is worth paying attention to the isSorted parameter, which is True by default. In my experience this parameter is best set to False in order to avoid Salome unpredictably changing the order of the objects in the resulting list. For example, here I have a Compound of two objects A and B, which has the faces glued resulting in Glue_1....

November 29, 2013 · Simon

How to call Salome from an external program

Intro For a while I have been using Salome to create finite element models. I really like the geometry module, and the fact that one can reuse entities that have been used for, say, a volume boolean operation. I have also got used to the meshing module now. Like with most really powerful software, once you get used to its special way of doing things it is plain sailing. Perhaps coming from a different software suite made things harder to learn rather than easier....

October 29, 2013 · Simon