Ben North's blog.

Covering various topics, usually of a vaguely nerdy nature.
Contact: ben@redfrontdoor.org

05 August 2015

Mono Lake alkali flies in JavaScript

We recently went on a fantastic family camping trip to California, travelling round various National and State Parks. One of the places we saw was Mono Lake. There are lots of interesting aspects to Mono Lake, but this post concentrates on one of them: the vast numbers of alkali flies which live on the waterline. […]

26 July 2015

Guess Poo: An application of nearly-orthogonal fractional factorial design

We have the game ‘Guess Who’, which comes with a selection of sheets to play variants of the original game. In a flash of comedy inspiration, my eldest, Meg, and I thought it would be excellent if there was a game called 'Guess Poo'. In Guess Poo, instead of trying to identify faces, you have […]

08 June 2015

Faint amusement from arrows

In logic, we talk about propositions, giving them names, say p or q. For example, p might be the proposition 'it is raining', and q the proposition 'I will get wet'. Then to represent the proposition 'if it is raining then I will get wet', we can say 'p IMPLIES q', which is often written […]

08 April 2015

A game of multiples and divisors

I saw an interesting number-based game at the 2015 Young Scientist show. This post derives, using brute force, a winning strategy for the game and implements it as a 'human vs computer' setting.

16 January 2015

Post-specific Javascript and CSS in WordPress

A couple of recent posts here — An oscillator from a jam-jar lid The value of a second opinion — required some post-specific Javascript and CSS styling. It took me a little while to figure out how to achieve this, given my limited exposure to PHP in general and WordPress programming in particular. This is […]

16 December 2014

The value of a second opinion

You feel ill and go to a doctor. She does a test and says 'you have a 70% chance of having the Lurgy'. You go to a different doctor, who does a different test, but also says 'you have a 70% chance of having the Lurgy'. Given these two test results, what are your chances of having the Lurgy?

09 November 2014

Tiny patch to git

A one-character documentation fix for 'git'.

17 July 2014

Failure: playing video from audio cassette

The idea for this project came from a few different places: Curiosity about how cable modems actually transmit ones and zeros along the coax cable. This led to some reading about the various modulation methods used. Code I'd written to read the data on cassette tapes containing files from the Dragon 32 computer of my youth. […]

08 June 2014

A Simon-playing robot

My 7-year-old daughter and I built a robot which plays the memory game 'Simon'. Servos use string to pull 'fingers' made out of Lego, pressing the game's buttons. Phototransistors sense which lights are flashing, with an Arduino controlling everything. It successfully plays a complete game of Simon!

16 May 2014

Free Software collaboration at the National Library of Ireland

RTE recently carried a news piece announcing the release of a large volume of historical digital images by the National Library of Ireland. One detail in the piece caught my eye: it quoted the library's Digitisation Programme Manager Sara Smyth as saying Since 2010, we have overhauled our digitisation workflows and put in place key […]