Carrier wave Updated +Created
Early transmitters such as the spark-gap transmitter could only send noises to send Morse code.
To send voice and music, amplitude modulation had to be developed. And a key ingredient of this is the carrier wave.
The problem is, the carrier wave needs to have somewhat high frequencies, in the hundreds of kHz TODO why. But as you might imagine, that is hard to achieve by mechanical means such as a hand cranck like Hippolyte Pixiis alternator!
Interestingly, some of the first carrier wave generators were actually mechanical, e.g. the Alexanderson alternator.
But clearly such mechanical machines were not very scalable, and soon more electronic devices were introduced, notably the vacuum tube.
Cascading Style Sheets Updated +Created
Cataclysm DDA build from source on Ubuntu 21.10 Updated +Created
sudo apt build-dep cataclysm-dda-curses cataclysm-dda-data cataclysm-dda-data
git clone https://github.com/CleverRaven/Cataclysm-DDA
cd Cataclysm-DDA
git checkout cdda-experimental-2022-01-27-0622
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DTILES=ON -DSOUND=ON -DLOCALIZE=OFF ..
make -j`nproc`
fails with:
:part_index_’ may be used uninitialized [-Werror=maybe-uninitialized]
   55 |             return part_index_;
as reported at: github.com/CleverRaven/Cataclysm-DDA/issues/52657 now open for 3 months. Basically every commit I tried fails with a different -Werror check, they don't test GCC new enough regularly.
Cataclysm DDA multiplayer Updated +Created
This would be a dream, but it is also impossible: how can you reconcile automated tasks that are simulated quickly like batch crafting 20 muffings in 30 in-game minutes, with someone who is at the same time fighting a hoard of zombies and taking one action every 2 in-game seconds? Alas.
Cataclysm DDA save scum Updated +Created
Tested as of Cataclysm: Dark Days Ahead 0.E-3-1, seems possible built-in:
  • Disable autosave on settings
  • Quisave (Esc + 9)
  • To restore the save, just close the game window directly before clicking Yes or No on the "Watch the last moments of your life" dialog.
A less risky save scum can be achieved with rsync:
rsync -av ~/.local/share/cataclysm-dda/save/ ~/.local/share/cataclysm-dda/save.bak/
and after you die:
rsync -av ~/.local/share/cataclysm-dda/save.bak/ ~/.local/share/cataclysm-dda/save/
Cavity magnetron Updated +Created
Apparently, DC current comes in, and microwaves come out.
TODO: sample power efficiently of this conversion and output spectrum of this conversion on some cheap device we can buy today.
Video 1.
Magnetron, How does it work? by Lesics (2020)
Source.
Video 2.
Device that Won WW2 by Curious Droid
. Source.
Cayley graph Updated +Created
You select a generating set of a group, and then you name every node with them, and you specify:
  • each node by a product of generators
  • each edge by what happens when you apply a generator to each element
Not unique: different generating sets lead to different graphs, see e.g. two possible en.wikipedia.org/w/index.php?title=Cayley_graph&oldid=1028775401#Examples for the
CC BY-NC-SA Updated +Created
Too restrictive. People should be able to make money from stuff.
The definition of "commercial" could also be taken in extremely broad senses, making serious reuse risky in many applications.
Notably, many university courses use it, notably MIT OpenCourseWare. Ciro wonders if it is because academics are wary of industry, or if they want to make money from it themselves. This reminds Ciro of a documentary he watched about the origins of one an early web browsers in some American university. And then that university wanted to retain copyright to make money from it. But the PhDs made a separate company nonetheless. And someone from the company rightly said something along the lines of:
The goal of universities is to help create companies and to give back to society like that. Not to try and make money from inventions.
TODO source.
The GNU project does not like it either www.gnu.org/licenses/license-list.en.html#CC-BY-NC:
This license does not qualify as free, because there are restrictions on charging money for copies. Thus, we recommend you do not use this license for documentation.
In addition, it has a drawback for any sort of work: when a modified version has many authors, in practice getting permission for commercial use from all of them would become infeasible.
en.wikipedia.org/wiki/Creative_Commons_NonCommercial_license#Defining_%22Noncommercial%22 also talks about the obvious confusion this generates: nobody can agree what counts as commercial or not!
In September 2009 Creative Commons published a report titled, "Defining 'Noncommercial'". The report featured survey data, analysis, and expert opinions on what "noncommercial" means, how it applied to contemporary media, and how people who share media interpret the term. The report found that in some aspects there was public agreement on the meaning of "noncommercial", but for other aspects, there is wide variation in expectation of what the term means.
Change of basis matrix Updated +Created
The change of basis matrix is the matrix that allows us to express the new basis in an old basis:
Mnemonic is as follows: consider we have an initial basis . Now, we define the new basis in terms of the old basis, e.g.:
which can be written in matrix form as:
and so if we set:
we have:
The usual question then is: given a vector in the new basis, how do we represent it in the old basis?
The answer is that we simply have to calculate the matrix inverse of :
That is the matrix inverse.
Charge conservation Updated +Created
Charitable organization Updated +Created
Charles Bukowski Updated +Created
Video 1.
Something for the touts
. Source.
We have everything and we have nothing
And some men do it in churches
And some men do it by tearing butterflies in half
and some men do it in Palm Springs
Laying it into butter-blondes with Cadillac souls
This stuck to Ciro's mind for some reason. His brain just keeps completing the sentence, over and over:
Ciro Santilli does it in his computers and in his labs!
Charles K. Kao Updated +Created
Figure 2.
2009 Nobel Prize lecture
. Poor Charles was too debilitated by Alzheimer's disease to give the talk himself! But if you've got a pulse, you can get the prize, so all good.
Charles Simon Updated +Created
Basically it looks like the dude got enough money after selling some companies, and now he's doing cooler stuff without much need of money. Not bad.
Chart Updated +Created
Cheap oscilloscope Updated +Created
Video 1.
DIY Oscilloscope Kit (20$) VS Regular DS Oscilloscope (400$) by Great Scott (2016)
Source.
Video 2.
Hantek 6022BE Review by Adrian's Digital Basement (2022)
Source.
Chemical bond Updated +Created
Chemical company Updated +Created
Chemical compound Updated +Created
The definition does not include homonuclear molecules which is a pain.

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