user134450

joined 2 years ago
[–] user134450@feddit.de 11 points 1 year ago

that is not a power plant. a power plant supplies power…

[–] user134450@feddit.de 3 points 1 year ago (1 children)

So what does this say about the dark matter deficient galaxies? https://www.nature.com/articles/s41550-019-0930-9

[–] user134450@feddit.de 148 points 1 year ago (7 children)

What makes them think that the library of Alexandria did it any other way? Nerds have existed long before the internet…

[–] user134450@feddit.de 2 points 1 year ago

Yep this is the official way. There is also the quick and dirty way of adding a new ID to your existing key to enable its use with a different email sender, but be wary of the info leaks this could lead to…

[–] user134450@feddit.de 2 points 1 year ago (1 children)

If you want to be super exact about it it would be roughly 4 times the mass of limescale + mass of already dissolved CaCO~3~ in your tap water (you can look that up if you know the hardness index of your water).

But really just don't be stingy with citric acid and it will be fine is what i am saying.

Here is the math:

::: spoiler Spoiler

2 frac {210.14 g/mol } {100.0869 g/mol} approx 4.2

[–] user134450@feddit.de 6 points 1 year ago (5 children)

Note that citric acid works a bit more nuanced than many other descalers: it acts as a chelating agent at high concentrations (2x the Ca2+ concentration) and is more effective at removing scale because of this effect, but at lower concentrations the effect might actually be reversed because it can form solid calcium citrate, which has a very low solubility in water.

If you are using citric acid based descaler you should make sure that you are always using enough of it to avoid the formation of calcium citrate.

[–] user134450@feddit.de 2 points 1 year ago

I think they are referring to Uranium with natural isotopic abundance. Which is complete bullshit when you put a picture of a nuclear power plant behind it – which in most cases can not function with the natural isotopic abundance (heavy water reactors being the exception, not the rule).

[–] user134450@feddit.de 4 points 1 year ago* (last edited 1 year ago)

first you would need to know what COP you could reasonably get, which among other things depends on the average outside temperature during heating season if you want to use an air sourced heat pump.

The COP can be in a largish spectrum depending on these factors but typical values are 3.5 for average homes in temperate climate. Higher if you live in a warmer climate and lower if you live closer to the arctic. If you want to really do the math it might be good to get help from a professional specialising in heat pumps.

Edit: this is for heating use only. A heat pump can also be used for cooling but then the climate effect is inverted.

[–] user134450@feddit.de 2 points 1 year ago

Uhhh you realize there are muskets hanging on the wall, right? I think its fair to say they don't just make swords :)

[–] user134450@feddit.de 2 points 1 year ago

It's just the basic posix shell syntax. It just looks weird because they are using lots of library functions and in-place substitutions. also apparently the function, to translate a system path to something grub will understand, is an ELF binary 0_o

[–] user134450@feddit.de 3 points 1 year ago* (last edited 1 year ago) (2 children)

check the GRUB_CMDLINE_LINUX key in /etc/default/grub it should contain the info about any subvolume. if it does not then there might be another grub config hook that is used by Fedora to add that info. If you want to be able to change subvol names without having to touch the grub config you might also want to switch to using subvolid instead of subvol keys on the kernel command line, because the id will stay the same after a rename (this could backfire though if you assign functions to certain names like "fallback" etc.).

Edit: found the hook that adds the kernel command line option for btrfs subvolumes. in /etc/grub.d/10_linux there is this bit of code:

case x"$GRUB_FS" in
    xbtrfs)
        rootsubvol="`make_system_path_relative_to_its_root /`"
        rootsubvol="${rootsubvol#/}"
        if [ "x${rootsubvol}" != x ]; then
            GRUB_CMDLINE_LINUX="rootflags=subvol=${rootsubvol} ${GRUB_CMDLINE_LINUX}"
        fi;;
    xzfs)
        [skipped for brevity]
        ;;
esac

so it seems it is always looking at the subvol name of the currently mounted root fs.

[–] user134450@feddit.de 9 points 1 year ago

also: you can calculate the carnot cycle efficiency of a solar cell as if it was a classical heat-power-machine, even though it has no visible moving parts.

the reason why this works and yields realistic results is because the basic principles of thermodynamics stay the same no matter if you are working with steam, combustion gasses or photons and electron gas inside a semiconductor.

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