Viewing posts by christian

Matching coloured LED combinations to a spectrum

A previous blog post provides a class, ColourSystem, which can be used to predict the colour (within some colour system) of a provided spectrum. This post uses the class to determine how to combine a number of light emitting diodes (LEDs), or other light sources with known spectra in order to produce light with a given spectrum. This task is not as simple as fitting a linear combination of the LED spectra to the given spectrum because the colour matching functions determining the tristimulus values (which, in turn model the colour perceived by the human eye) vary with wavelength and overlap. Also, LEDs emit light, so no negative coefficient in such a linear combination can be allowed.

Animated landscapes with Matplotib

Just a quick experiment in creating animated surfaces in Matplotlib. The distortions to the plane are sine waves applied in octaves with a random phase, $\phi_n$:

Animated contour plots with Matplotlib

A quick project inspired by this tweet by @story645 referencing Jacques Bertin's Semiology of Graphics.

Python Quiz Advent Calendar: explanations

Here are the explanations for the Python Quiz Advent Calender puzzles which appear over December 2020.

Uranium enrichment and the separative work unit (SWU)

Natural uranium consists largely of two isotopes, $\mathrm{^{235}U}$ and $\mathrm{^{238}U}$. The less-abundant (0.72%) isotope, $\mathrm{^{235}U}$ , is important for nuclear reactors and weapons because it is the only isotope existing in nature to any appreciable extent that can sustain a fission chain reaction (that is, it is fissile).