# Monthly archives: March, 2014

## “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.” Well, I couldn’t pass up the chance to help old voyeur out with that.

## Solution

If 1 million miles is equivalent to 6 points

1,000,000 miles = 6 points

So, to work out the number of points equivalent to a mile we have

1 mile = 6/1,000,000 points = 0.000006 points

## But how many miles to a point, goddamit?

It’s 1 million divided by six, innit.

1 point = 1,000,000/6 miles = 166666.667 miles (to 3.d.p.).

### 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. Currently, all high-performance permanent magnets contain expensive rare earth elements such as Nd and Dy. We want to design new magnets that are cheaper and create less environmental damage through mining. One way to do this is with new magnets that are nanostructured to take advantage of shape effects.

In the paper we use micromagnetics simulations to assess the limits of shape contributions to the reversal stability of soft and semi-hard elongated magnetic particles.
We show that in materials with moderate uniaxial magnetocrystalline anisotropy the addition of shape anisotropy can double the coercive field.

In soft magnetic cylinders nucleation of a reversed domain starts at the corners at the end and smoothing the edges can improve the coercive field by about 10 %.
In further simulations we compacted soft magnetic cylinders into a bulk-like arrangement, where misalignment and magnetostatic interactions cause a spread in the switching field.  We also show that magnetostatic interactions reduce the coercive field in compacted rod arrangements by up to 20 %.

The preprint can be downloaded here or on ArXiV (the ArXiv version will be updated to a revised version in the next few days).

### 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. Well, it seems it can do a lot of cool stuff, so if you are interested I suggest you go to the homepage.

I decided to test it out on Ubuntu 13.10. My test file was the seminal paper by Stoner & Wohlfarth “A mechanism of magnetic hysteresis in heterogeneous alloys”.

Well, it did a pretty good job with the default settings, although there are some problems on pages where the standard 2-column layout switches to 1-column for large equations etc. The converter split those equations over two pages, making it very hard to read them. There are also some parts where footnotes and the title at each page header break up the flow of the text and would ideally have been removed.

Still, the results were quite impressive. I know how hard it must be for a program to accurately parse a complicated PDF file, and I gave it a very difficult test article. Perhaps with easier files the results will be even better. I tried it again with Thiaville and co-workers “Domain wall motion by spin-polarized current: a micromagnetic study” and this time the results were pretty much perfect. This paper has a standard Journal of Applied Physics layout and is well formatted. The only issue was that, again, the page headers and footers from the original A4 PDF pages appear in the middle of the reflowed text. This isn’t such a big problem but it could be a little distracting, and we all know that reading hardcore scientific papers requires all of our concentration sometimes!

Until I have a 13.3 inch eReader (Onyx Boox say that they will be releasing one around Autumn 2014) I will stick to a combination of reading from my notebook screen (tiring) and printing select papers (wasteful) but now using k2pdfopt I can better utilize my Kindle too.

### 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).

Cool code wall