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two_handfuls commented on Economics of Orbital vs. Terrestrial Data Centers   andrewmccalip.com/space-d... · Posted by u/flinner
torginus · a day ago
Out of curiosity, I plugged in the numbers - I have solar at home, and a 2 m2 panel makes about 500w - i assume the one in orbit will be a bit more efficient without atmosphere and a bit more fancy, making it generate 750w.

If we run the radiators at 80C (a reasonable temp for silicon), that's about 350K, assuming the outside is 0K which makes the radiator be able to radiate away about 1500W, so roughly double.

Depending on what percentage of time we spend in sunlight (depends on orbit, but the number's between 50%-100%, with a 66% a good estimate for LEO), we can reduce the radiator surface area by that amount.

So a LEO satellite in a decaying orbit (designed to crash back onto the Earth after 3 years, or one GPU generation) could work technically with 33% of the solar panel area dedicated to cooling.

Realistically, I'd say solar panels are so cheap, that it'd make more sense to create a huge solar park in Africa and accept the much lower efficiency (33% of LEO assuming 8 hours of sunlight, with a 66% efficiency of LEO), as the rest of the infrastructure is insanely more trivial.

But it's fun to think about these things.

two_handfuls · a day ago
Yes it's fun. One small note, for the outside temp you can use 3K, the cosmic microwave background radiation temperature. Not that it would meaningfully change your conclusion.
two_handfuls commented on Using Python for Scripting   hypirion.com/musings/use-... · Posted by u/birdculture
Lvl999Noob · 4 days ago
And for the opposite, where you keep your main pipeline in shell but want to use python for some parts of it, there is pypyp.

https://pypi.org/project/pypyp/

It takes cares of the input and output boilerplate so you can focus on the actual code that you wanted python for.

    > seq 1 5 | pyp 'sum(map(int, lines))'
    > ls | pyp 'Path(x).suffix'

two_handfuls · 3 days ago
So cool! I made pawk [1] to get some of the same features, but yours is better! Congrats!

[1] https://github.com/jean-philippe-martin/pawk

two_handfuls commented on In New York City, congestion pricing leads to marked drop in pollution   e360.yale.edu/digest/new-... · Posted by u/Brajeshwar
margalabargala · 6 days ago
No, it doesn't.

With the ICE car, if you want to go 55, you might accelerate to 57 and then coast down to 55 without using brakes.

With an EV you might accelerate to 57 and then brake to 55 when you let off the accelerator.

Tire wear is a function of how often you use your tires to slow down the car. With an ICE car that's every time you hit your brakes. With an EV that's both brakes and regen. An EV's time spent braking or regenning is more than the time an ICE car spends braking.

Someone could design an EV that behaves the way you describe, but aggressive regen sells better, so no one does.

two_handfuls · 6 days ago
Coasting wears your tires too. By the same amount.
two_handfuls commented on In New York City, congestion pricing leads to marked drop in pollution   e360.yale.edu/digest/new-... · Posted by u/Brajeshwar
SoftTalker · 7 days ago
Modern diesel engines with DPF and DEF are pretty clean from a particulate and NOx standpoint. Of course there are still older diesels on the road, mainly buses and trucks. In the USA, diesel is so unpopular as a passenger car engine that it's not even worth worrying about.
two_handfuls · 6 days ago
We would believe that except that car companies are known for lying about diesel emissions.
two_handfuls commented on In New York City, congestion pricing leads to marked drop in pollution   e360.yale.edu/digest/new-... · Posted by u/Brajeshwar
margalabargala · 6 days ago
Firstly, the motors absorb half the energy. The other half goes to the tires. It would be great and efficient if the motors could.absorb it all but unfortunately physics doesn't work that way.

Secondly, if you've ridden in an EV, you would know that the drivers/cruise control often apply regent braking in situations where an ICE vehicle would have simply coasted to a stop. Hence more wear.

two_handfuls · 6 days ago
The tires wear the same amount here because either way, the car decelerates by the same amount at roughly the same rate.
two_handfuls commented on First PC Emulator Launched for Galaxy XR   github.com/SimonJGillespi... · Posted by u/simonjgillespie
simonjgillespie · 7 days ago
FYI- If you look very closely at the video tile on the bottom left you will see XR inside XR. You can't get that capability anywhere else.
two_handfuls · 7 days ago
XR means "VR or AR". Having a passthrough window inside of a VR environment has been done before.

If you meant something else then I apologize for the misunderstanding (on phone, not going to be able to see fine detail in a video).

two_handfuls commented on First PC Emulator Launched for Galaxy XR   github.com/SimonJGillespi... · Posted by u/simonjgillespie
simonjgillespie · 7 days ago
The PC is in a passthrough environment with the screen floating in mid air. I use it on a daily basis.

This is our promo video and its very clear it's in XR with passthrough. https://studio.youtube.com/video/At7KdrGfTTg

We also have a number of XR widgets which are not enabled by default (Holodeck for example). They will be turned on soon in a pro version so if thats what you're looking for I am delighted!

Try the download if you don't believe me.

two_handfuls · 7 days ago
Thank you! I believe you. If you work at Samsung, maybe you can get them to make the "Galaxy XR" landing page mention passthrough then? Because if it does, I missed it.

While we're at it, Samsung may have its reasons to mention "Google Photos" prominently as the first concrete application, but to me as a user that decoded as "ok they have no games to speak of." (I don't know if that's true, but that's how it comes across).

two_handfuls commented on First PC Emulator Launched for Galaxy XR   github.com/SimonJGillespi... · Posted by u/simonjgillespie
two_handfuls · 7 days ago
For thise who, like me, needed context:

"Samsung XR" is a VR headset running "Android XR". Being called "XR" I would expect it would have AR abilities but the website makes no mention of it, or even passthrough, that I could see.

two_handfuls commented on Multivox: Volumetric Display   github.com/AncientJames/m... · Posted by u/jk_tech
PetitPrince · 12 days ago
> imagine a spinning display like those of the article but somehow tuned so that they are only visible when exactly head on

I don't understand: doesn't defeat the purpose of a volumetric display (seeing what is displayed from multiple point of view) ?

two_handfuls · 12 days ago
This would be a poor man's "lightfield" display: as you move left or right you see a different perspEctive, just like you would if it were a physical object on the table instead of the spinning screen contraption.

So you would indeed see different points of view.

two_handfuls commented on Multivox: Volumetric Display   github.com/AncientJames/m... · Posted by u/jk_tech
ruined · 12 days ago
that's just a flat display with extra steps
two_handfuls · 12 days ago
It’s different from a flat display in that if you walk around it, you see a different perspective. And it works with any number of viewers.

u/two_handfuls

KarmaCake day947April 16, 2021View Original