I grew up understanding that one of Tesla’s big innovations was using AC to transmit power distances so that there weren’t tremendous losses and line meltings or something. Can someone help me reconcile the delta between this understanding and the above comment? Was this not actually a thing? Or have we overcome it somehow?
HVDC is a miracle of modern engineering that could not have been done in the days of Tesla. It removes several sources of losses that otherwise would have turned valuable power into heat. That said, it isn't without drawbacks: the cables are quite expensive, harder to repair and somewhat fragile, and 'local stepdown' which otherwise would just be a properly rated (capacity and insulation) transformer now turns into a much higher technology exercise. HVDC is for now relegated to a long haul role not unlike oil pipelines compared to the AC network which is far more interconnected and wide spread. You are unlikely to see HVDC used for lower level distribution in the next decade, just as you are unlikely to see your local gas station hooked up to an oil pipeline.
DC is also much harder to switch than AC; the latter has zero-crossings which tend to extinguish any arcs that form, but DC will just keep going. Look at the DC vs AC ratings on switches and you'll see a huge difference.
It can be either AC or DC. Aluminum TIG welding uses AC, whereas you'd use electrode-negative DC for steel or copper. As I understand it, with aluminum you need the electrode-negative part of the waveform to transfer heat to the work piece, but you need the electrode-positive part of the waveform to clear out the crud that accumulates in the electrode-negative part. Often you set a lopsided duty cycle and use different frequencies depending on how deep you want the weld to penetrate.
If you go to 100% electrode positive you tend to heat the metal rather poorly, but can turn the end of your tungsten electrode into a molten blob -- which is usually not desirable.
> the cables are quite expensive, harder to repair and somewhat fragile
Nope, HVDC uses the same style of cable as AC. I'm not sure why you'd think they'd be different.
The HVDC cables that can be expensive are meant to be submerged. A feat that only HVDC can do. HVAC can't be submerged due to the capacative effect.
But otherwise I agree. It's more a pipedream for me that HVDC becomes more common place as I believe it'd make grids ultimately more stable and resilient.
Hm, yes, you are right, I must have been reading on submerged cables, but it's a while ago.
The devil is in the details here, AC tri-phase cabling can not easily be re-purposed for HVDC purposes because you only have a pair of conductors rather than three 120 degree out of phase lines. So while technically the cable itself can be the same the carrying capacity of a triple of conductors would be reduced and one of the conductors would be idle, so if this is an in-ground or overhead cable not specifically made for DC that is a lot of wasted carrying capacity.
I get your point but it goes too far in the opposite direction. We should now discuss absolutely nothing in relation to Sora and genAI videos? That seems overly charitable to the platform.
Agreed. I did try this out! So the reply to the original comment is dumb. I actually dismissed it for being flippant.
Your reply is more interesting. Hence my (albeit maybe snarky) chiming in. So the original comment does end at a very specific app/sora related conclusion. "Sora didn't keep us coming back."
If I may amend your scenario: imagine this bar is actually in the center of SF or across the street from Open-AI or whatever. We're on HN discussing a post on X about Sora.
The appeal to humanity is not wrong. My point is more let's keep the connection with that humanity in relation to AI, to Sora, to what's going on in this forum.
The way it works is that Apple would have committed more resources if the projected outcome was more revenue. By choosing to approach it as a free option, they committed a free option's worth of resourcing to it.
You seem confident and well-informed. Can you tell us about the time of day, visibility conditions, and what it’s like driving a fire truck at an airport? We should really get this judgment to the driver ASAP.
In Canada (and I’m sure elsewhere) there are surprise inspections where government inspectors show up at petrol stations and see if the pump actually gives you what it claims.
I have a feeling that if the USA did random, surprise inspections on businesses to make sure what they were selling was actually as-advertised, the whole system would be exposed as fraud within a month.
In the US every gas pump I've seen (I have not check the majority of states, but still a good sample) has a sticker on it stating inspections and who runs the state department that inspects them. Usually it is a yearly inspection (at least according to the sticker, maybe they do it more often I don't know)
Not just gas pumps, but any measuring device used to determine the price of a metered product. The scales at the register at supermarkets also have calibration stickers in my state.
Now that you mention it, I've seen them at some grocery stores - but generally not in a place I'd be looking unlike gas pumps where is is right next to the price and so you won't miss it.
I don't know if other companies do this anywhere but if you live in Ireland. Diageo have roles for people to travel around the country doing precisely this.
Nah. Remember the episode where Geordi asked the computer to create an opponent worthy of Data instead of Sherlock Holmes, and the computer creates sentient Moriarty with the ability to control the ship.
That sounds exactly like something an LLM based system would do.
Not really an example that proves any point, but one that comes to mind from a 20-year-old game:
World of Warcraft (at least originally) encoded every item as an ID. To keep the database simple and small (given millions of players with many characters with lots of items): if you wanted to permanently enchant your item with an upgrade, that was represented essentially as a whole new item. The item was replaced with a different item (your item + enchant). Represented by a different ID. The ID was essentially a bitmask type thing.
This meant that it was baked into the underlying data structures and deep into the core game engine that you could never have more than one enchant at a time. It wasn't like there was a relational table linking what enchants an item in your character's inventory had.
The first expansion introduced "gems" which you could socket into items. This was basically 0-4 more enchants per item. The way they handled this was to just lengthen item Ids by a whole bunch to make all that bitmask room.
I might have gotten some of this wrong. It's been forever since I read all about these details. For a while I was obsessed with how they implemented WoW given the sheer scale of the game's player base 20 years ago.
“Insight porn” is a new term for me but it seems to fit so well.
I think a key part of it is not just the simplification of complicated issues, but the willingness to oversimplify them in a way even if it perverts the message. It’s a cousin to “just blame immigrants” or “all cops are bastards” or “____ considered harmful.”
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