perestroika

joined 2 years ago
MODERATOR OF
[–] perestroika@slrpnk.net 1 points 6 days ago

Regardless of whether an opinion is for or against something, the recommended subject matter of this community is definitely not smart cities, but off-grid living.

[–] perestroika@slrpnk.net 1 points 6 days ago* (last edited 6 days ago) (2 children)

smart cities

There must be a better community for that. A city, especially a smart city, would not be considered off grid.

I am not a member there, but I would take a look at "c/urbanism". It is about cities.

[–] perestroika@slrpnk.net 1 points 1 week ago* (last edited 1 week ago) (4 children)

Moderator of community, not admin of instance.

[–] perestroika@slrpnk.net 1 points 1 week ago (6 children)

Exotic, rare, not representative of everyday things.

[–] perestroika@slrpnk.net 1 points 1 week ago (8 children)

Here's a reasonably representative photo.

[–] perestroika@slrpnk.net 1 points 2 weeks ago

As much as I've understood, yes - heat pumps have difficulty with reaching high temperatures.

[–] perestroika@slrpnk.net 1 points 2 weeks ago* (last edited 2 weeks ago) (11 children)

No. Also, I apologize for being a bit rude, but what would you gain from having a video of a home wind generator working? There's probably thousands of such videos on the Internet.

[–] perestroika@slrpnk.net 2 points 2 weeks ago (2 children)

They use resistive heating, so they can only charge it dirt cheap when there is surplus solar or wind.

[–] perestroika@slrpnk.net 2 points 2 weeks ago* (last edited 2 weeks ago) (13 children)

The question is too vague to answer well, but I have run a high autonomy household for 10 years, so it's possible. Solar with battery storage, small wind generator to supplement things during storms. Heating uses wood.

Latitude 59, so I get an electrical energy crisis every winter, but on most winters, I don't have to start a gasoline generator or bring electricity over with my e-car.

If you're on a lower latitude, it becomes simpler, if you only have enough surface for solar panels.

[–] perestroika@slrpnk.net 8 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

It's a pretty neat system:

  • can be set up anywhere
  • can supply high grade heat (process heat, not mere space heating heat)

However, heat stores are subject to scaling laws which don't favour sand on the large scale, at least unless it's underground (and then you have to keep groundwater out to avoid vaporizing it). Large thermal stores benefit from storing heat in water, and placing the water deep underground, so the boiling point rises. If local rock has low thermal conductivity, even better.

For comparison Helsinki (.fi) has a 10 GWh underground thermal store. Where I live, Tallinn (.ee) will soon get a 1 GWh surface thermal store. And Vantaa (.fi) will soon complete a whopping 90 GWh thermal store that's located 100 m underground, so their water will boil at 140 C instead of the usual 100 C. Boiling points up to 300 C are attainable in practise, then the curve starts leveling out.

[–] perestroika@slrpnk.net 1 points 2 weeks ago (1 children)

It was meant to be humorous framing, given the impossibility of making humans from magma or the iron core. :)

[–] perestroika@slrpnk.net 2 points 3 weeks ago* (last edited 3 weeks ago) (1 children)

Which ethnicity’s population are we going to reduce?

I honestly believe that "we" aren't going to do jack s**t. It's a process which is nearly unsteerable. People are going to live longer and longer, and use resources that would otherwise be used by children they might have had. Society is going to be burdened by caring for the old, and this is going to reduce chances of caring for the young.

In nearly every developed country, population growth is slowing or population has already started decreasing. Only in the least developed regions (some areas of Africa) does the opposite still apply, but UN predictions (made by competent people) suggest the process just reaches there later.

So, every ethnicity's population is going to be reduced. Every ethnicity can also consider if their numbers are adequate, too high or too low. If a nation feels threatened by disappearing from the maps, they can try to reorganize their society. Random ideas: a few laws that give parents various health and social security guarantees regardless of their employment status, especially in case they're single parents, then maybe create a few dating sites that actually try to help their users find people they like, etc...

 

Living off grid often correlates with poorly accessible locations - because that's where the infrastructure is not.

On certain latitudes, especially near bodies of water, especially in remote locations - do not ask who the snow comes for - it always comes for you (and with a grudge). So, what ya gonna do?

Over here, a tractor being incomplete (it is great folly to go into winter with an incomplete tractor), snow is handled by an electric microcar. Since the microcar is made of thin sheet metal and plastic, it cannot carry a plow... but the rear axle being solid steel, it can pull one.

The plow is one year old, and was previously pulled by a gasoline car. It is made of construction steel: 8 mm L-profiles shaped like a letter A with double horizontal bars. The point of connection on top ensures it doesn't lift too much while plowing. It's currently fixed with an unprofessional and temporary C-clamp (there will be an U-bolt soon). It is pulled with a chain.

If snow is heavy, the L-profiles lift the plow on top of snow, and you have to plow the same road many times. Sometimes it veers off sideways. Generally, you have to catch the snow early with this system - if you're late, you're stuck. :)

Not many advantages, but dirt cheap. Don't go plowing public roads with such devices - it is nearly invisible to fellow drivers, and cops would get a seizure.

 

Some Chinese researchers have found a new catalyst for electrochemically reducing CO2. Multiple such catalysts are known, but so far, only copper favours reaction products with a carbon chain of at least 2 carbons (e.g. ethanol).

The new catalyst requires a specific arrangement of tin atoms on tin disulphate substrate, seems to work in a solution of potassium hydrogen carbonate (read: low temperature) and is 80% specific to producing ethanol - a very practical chemical feedstock and fuel.

The new catalyst seems stable enough (97% activity after 100 hours). Reaction rates that I can interpret into "good" or "bad" aren't found - it could be slow to work. The original is paywalled, a more detailed article can be found at:

Carbon-Carbon Coupling on a Metal Non-metal Catalytic Pair

Overall, it's nice to see some research into breaking down CO2 for energy storage, but there is nothing practical (industrial) on that front yet, only lab work.

 

To make no excessive claims, I have to admit I burnt a fair bit of wood during the night. In the morning however, around 9 o'clock, the solar fence (nominal power 2400 W) was giving 600 W and steaming vigorously. By 10 o'clock, it had thawed and gave 940 W. Later, other panel arrays took over and wattage decreased. The energy was used to run a heat pump.

P.S. Knowing that server resources aren't infinite, I hosted the image externally, I hope that hosting on "postimages.org" works smoothly.

11
submitted 2 years ago* (last edited 2 years ago) by perestroika@slrpnk.net to c/abolition@slrpnk.net
 

The short war which Azerbaijan waged against Armenian-populated Karabakh after a months-long blocade is over (Armenian separatists lost, and will likely get ethnically cleansed out of the region)...

...but in the aftermath, it's worth pointing out that several high-profile Azeris did speak against their government starting a war - and were repressed.

The most worrisome case is the chairman of the confederation of trade unions, Afiaddin Mammadov. A provocateur who had previously injured himself threw a knife at him, and cops arrested him immediately after that, claiming he had injured the provocateur.

 

To my knowledge, this is the second time a sample is returned from an asteroid to Earth - only preceded by Hayabusa-2 fetching a sample from asteroid Ryugu. The capsule has been found and the sample stabilized with nitrogen. Fetching the sample required 7 years, studying it will require a bit of time too.

It is too early to speculate whether interesting discoveries will follow, but Bennu is considered to be an interesting asteroid - likely not a break-up product, but something that represents the original composition of the solar system.

Bennu is also considered a hazardous space object, ranked high on the Palermo scale of impact risk and kinetic yield, so knowing what it's made of can be practically worthwhile.

More information here:

https://en.wikipedia.org/wiki/OSIRIS-REx

 

The inverse vaccine, described in Nature Biomedical Engineering, takes advantage of how the liver naturally marks molecules from broken-down cells with “do not attack” flags to prevent autoimmune reactions to cells that die by natural processes.

PME researchers coupled an antigen — a molecule being attacked by the immune system— with a molecule resembling a fragment of an aged cell that the liver would recognize as friend, rather than foe. The team showed how the vaccine could successfully stop the autoimmune reaction associated with a multiple-sclerosis-like disease.

 

Most people would typically think than smelling a scent (unless it's a powerful poison or medicament) won't change much in a person's health... but apparently, a variation in the scent environment has effect on the human brain, especially if the person is already old and their senses are degrading. It has also been observed that viral infections damaging a person's olfactory nerves result in changes to the brain - with less input, the neural networks involved with scent tend to atrophy. Coinidentally, some neural networks involved with scent recognition are also involved with memory.

Prios studies already support the idea that training one's sense of smell helps older people avoid cognitive deterioration. This study brings highly significant statistical results and adds one bit - wakefulness is not required to benefit. Apparently, the stimulation a person receives from feeling different scents bypasses sleep (or maybe, even improves the quality of sleep).

 

Long story made short: apparently, the previous administration didn't really try (since it was Bolsonaro's, I am not surprised). EU import controls and financial interventions have also helped:

He believes the slowdown is due to a combination of factors: the resumption of embargoes and other protection activities by the government, improved technical analysis that reveal where problems are occurring more quickly and in more detail, greater involvement by banks to deny credit to landowners involved in clearing trees, and also wariness among farmers generated by the European Union’s new laws on deforestation-free trade. It may be no coincidence that deforestation has not fallen as impressively in the cerrado savanna, which is not yet covered by the EU’s controls.

 

Superconductivity is a condition of matter where resistance to electrical current disappears.

The first superconductors needed cooling to near the absolute zero. The next generation worked at temperatures of liquid nitrogen. A room-temperature atmospheric-pressure superconductor is a highly sought after material (e.g. it would expand possibilities to hande plasma for fusion research and make MRI machines easier to build).

A substance named LK-99 has recently caused interest in the research community. Its a copper-enriched lead apatite, typically made by reacting lead sulphate with copper phosphide. It is speculated to be superconductive at room temperature.

It is also thought that interesting properties are not inherent to the substance, but a particular kind of crystal lattice which this subtance obtains - if produced in certain ways.

The name LK-99 refers to Sukbae Lee and Ji-Hoon Kim, and the number refers to 1999, when these Korean researchers first stumbled upon it.

Studies back then were interrupted. They weren't certain of its properties and it was hard to make repeatably. When a researcher named Tong-Shik Choi died in 2017, he requested in his will that research into LK-99 be continued. The resources were found and his request was granted.

Then, other factors intervened, among them COVID. The first article was rejected by Nature because an extraordinary claim requires extraordinary proof. An article in Arxiv (not peer reviewed) at the end of July 2023 drew international attention, however.

Many persons and teams started attempting to replicate the experimental results. The process is still half way through, but considerable progress has been made.

  • Beijing University, school of material science + Beihang university: the experiment was made, but the effect could not be reproduced (they obtained a paramagnetic semiconductor of little interest)

  • Huazhong University, center for crystalline materials and micro/nanodevices: they obtained a diamagnetic crystal with interesting properties (repelled by a ferromagnet regardless of orientation, a property which a superconductor must have, but which is also shared by non-superconductive diamagnets)

  • National Physics Laboratory of India: failed to replicate the effect

  • Professor Sun Yue, South-Eastern University of China: got a weak diamagnetic crystal

  • Iris Alexandra (from Russia, plant physiologist): with an alternative production method, obtained a tiny but strongly diamagnetic crystal

  • Sinéad Griffin (Lawrence Berkley National Laboratory, from the US): published an article, attempting to theoretically explain how superconductivity might arise in the substance, explanatory tweet here

  • Junwen Lai (Shenyang National Material Science Laboratory, China): published an article about the electron structure of the substance, without opinion regarding superconductivity, with the opinion that gold doping would be better than copper doping

So, strong evidence is absent until now - we may have much merriness about nothing. There is a bunch of hypothesis and enough material to fit on a fingertip. :)

Background:

https://en.wikipedia.org/wiki/LK-99

 

I noticed that we have a community for talking about applied science and engineering in the form of c/technology, about climate science in the form of c/climate, but there didn't seem to be a field-neutral place to discuss any sort of science.

To fill the absence and introduce a few articles which caught my interest, I created it. I think I should make this thread stick to the top of the community, so meta-discussion could be easily located here.

 

People at MIT made a capacitor of cement and carbon black (not to be confused with soot). It worked and they are planning to test bigger samples. The construction of such capacitors is easy and they can be structural elements in architecture.

 

Summary: water + copper particles + room-temperature liquid metal (consisting of indium and gallium) = highly conductive gel with interesting properties.

Drying it slowly to evaporate the water allows simply getting conductive traces. Drying it fast allows printing objects that transform their shape when heated.

Commentary from me: indium and gallium are expensive metals. This is promising stuff, but not promising enough to go replicating at once. For most use cases, cables, soldering and PCBs are still the better option.

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