I was looking for an efficient algorithm calculating variance of a sliding window of the last n values an ongoing signal, and this came up.

Besides the content of the paper, the metadata on page 2 is interesting, as well as the barcode on the front page as well as the machine readable font accompanying the bar code. Did not know that was a thing in 1969 but maybe it was attached later in time.

How do you upload files to a sprite box then?

Russia started with mixing diodes into concrete a while ago- https://news.ycombinator.com/item?id=41933979

Some resources are still scarce. And a lot of those 6E24 kg is iron and nickel we can never get to. Another big fraction is basically molten stone. And we really should stop putting more carbon into the atmosphere.

Also, if you go for measures like mass processed, the weight of microchips, pcbs, parts is only a tiny fraction of what has to be processed and build in the supply chain.

Agreed that it is smarter to use oil for plastics then to burn it directly.

> Agreed that it is smarter to use oil for plastics then to burn it directly.

My argument is that as long as we are still burning oil and gas, we might as well burn old plastic instead of new oil and gas.

If/when we stop burning oil and gas, then we can think more seriously about recycling plastic.

You might like to read about https://en.wikipedia.org/wiki/Incineration and https://en.wikipedia.org/wiki/Waste-to-energy_plant

It's a fascinating topic. There's even more problems than the ones you bring up, but engineers are also pretty smart.

RFID tags are powered wirelessly, one could imagine powering smaller particles when operating on higher frequencies (RFID is on 13.something MHz requiring relatively large coils). A directional antenna could send a pulsed beam to power a subset of the particles in the area and afterwards receive their signals.

It needs to be in the infrared spectrum at least to be useful for smart dust, otherwise the package size is still dominated by the size of the antenna. Even mm-wave radar is marginal here.

So... smart dust powered by the sun? Cool!

Okay if you take dust literally. The important part is that the particles fly. Like dandelion seeds.

That sounds horrible.

The frequency resolution must be pretty bad though. You need 1 minute of samples for a resolution of 1/60 Hz. Hopefully the heartrate is staying constant during that minute.

It is about useful tricks you can usually not learn in university classes.

tricks of what kind

fast multiplying for example

Also how to make good estimates, and how to work with units.

One example, the formula to get the speed of a thing after h meters of free fall must deliver an outcome of m/s. We also know the gravitational acceleration g is given in m/s^2. Then, height h in m must somehow be part of the formula. We can get rid of the squaresecond in the denominator by drawing the square root. But then we also need the height in meters. Also it is clear that both more height as well as a higher acceleration must lead to higher speed. Therefore, the speed must be proportional to sqrt(h x g). In fact it is v = 1/2 sqrt(h x g) but we can derive the important part only from knowing how to calculate with units.

Especially the model 2 is very comfortable but probably also the leader of the incident statistics.

While it is true that that many problems where already visible 10 years ago, it is also true tat during the pandemic more trains were on time because having very few passengers speeds up the boarding/offboarding at stations enormously. So the pandemic somehow delayed the already inevitable fall into the abyss.