Heh, Gallager's original LDPC paper calls bits "binits"

Taking a look at codes again, and observing that it amounts to solving 3-SAT, but with soft decision inputs. This means no algorithm for decoding them will be fast and exact at the same time

Coming up with contingencies for the thermal design of the instrument. It involves white paint.. and gold! 🏆🌟🏅

@pettter has his thesis defense on order-preserving graph grammars today!

Procrastinating writing documentation by cleaning the lab

Today in the lab: measuring the instrument's moment of inertia along each cardinal axis using a trifilar pendulum. About 1% accuracy, and within theoretical bounds!

Tomorrow we get the result of the week-long vacuum test. The preliminary results have not been 100% conclusive, so it's turning to be a nail-biter :)

Getting somewhere.. Need to figure out where the bug that's causing those outliers is.. tomorrow!

Parsing and plotting calibration data. Just judging from the noise in this it looks like my bet (the green line) is the most promising :)

Entering day three of the vacuum test. All motors still spinning happily at 3600 RPM or so. Should be interesting to see how crusty the bearings are at the end of this..
Also transplanted the data logging to the raspberry pi to free up my laptop. Looks like we'll collect 50 MB of data in total over the week

thardin boosted

We've got a wager going in the lab regarding grounding metal shafts in vacuum. Three methods will be evaluated by running continuously for one week. The winner(s) get beer from everyone else :]

The science are multiplying!

I don't know the lower left moon language, but I'll try to translate the Swedish one:

'An inventor living in some backwater
wrote to the patent bureau last quarter
"I've halted the flow,
made vacuum-dried H2O,
you only need to add water!"'

.. as opposed to the silver plating we're currently using 🥈

Got a simplified version of my thermal model implemented in GNU Octave. So far I'm concluding that we'll want to polish all sides to decrease their solar absorptance and emissivity. That or gold plate one or two of them 🥇

I also had to just treat the internal radiative transfer as a black box (the central heptagon) since it'd just be a densely connected blob of jaggy lines

After some thought, here's my attempt at drawing all the ∞ heat sources, ☐■ thermal resistances and /\/\/\/ radiative heat transfers, including to/from the sun (s), moon (l), universe (u) and reflected sunlight (r)

Maybe someone on here knows a better way of drawing stuff like this?

It also turns out the instruments 100x100x1mm aluminium sides conduct more than enough heat toward the mounting plate on their own. Still, a full model is better

Working on the internal thermal model for our lunar instrument, which requires knowing view factors between all surfaces. After some headscratching and searching the Web for formulas, the view factors all turn out to just be 0,2 (to within a few tens of ppm) 😎

Hoo boy, I have six documents to produce in the span of a month. Documenting everything from requirements and interface stuff to handling procedures and critical points

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