Yikes, those bearings really start to howl as soon as the pressure starts to drop. Current spike too, from normal 200 mA @ 24 V up to 600 mA

The amount of formally verified code in the moon project now clocks in at 690 LOC, of which ~2/3 is annotations.

707 goals are currently proved by qed, alt-ergo, cvc4 and z3, in around four minutes on a laptop..!

Beyond knowing that all loops terminate and all memory accesses are within bounds, I also have numerical bounds on many variables. This helps verify that accumulators are using appropriate integer types and therefore can't overflow

Woop, motors plain bearings arrived from the workshop. Just have to wait until tomorrow for the glue to dry, then we can test them in vacuum over the easter weekend

-C quirk of the day:
int Q[3] = {0,0,0}; //this works
int Q[3] = {0}; //this doesn't

We're going back to pre-1800s tech in our instrument by switching the ball bearings in our motors to plain brass bearings. Hopefully if we make them just the right size they'll have "lagom" contact with the shaft, providing grounding, without being so tight that they just seize

thardin boosted
Spent four hours getting electron microscope and X-ray spectroscopy pictures taken today. Below is a zoomed-out view of a worn coil of silver plated copper wire https://social.umeahackerspace.se/attachment/597823

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 🥈

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