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This is a little incomplete... using a resistor divider or a variac ("halfway" switch) is not the only way to limit current -- switched mode power supplies (AC/DC or DC/DC converters) can limit current and/or voltage to arbitrary, programmable levels with efficiencies of as high as 98% (eg only 2% of energy lost as heat). They turn the output all the way on and all the way off according to a clock signal, with feedback loops connected to sensors at the output to regulate the output voltage or current.

It's still pulse modulation, just done really fast. So instead of using bang-bang at multi-second intervals, you do it at millisecond intervals (or in a modern DC/DC converter, down to ~500 nanosecond intervals)

Why this is not done on a hob/electric stovetop is purely a cost of manufacturing thing. There are solid-state relays that can switch 10 amps and reasonable service lifetimes but they cost $10+ each, and require implementing electronic controls (eg you have to use touch-buttons to set the heat level, or have analog-digital converters reading a rotary knob position...) and various other components, like needing to address current leakage from the solid-state-relay when it's off. The general guideline is you can expect retail value of a piece of electronics to be about 3x the component costs, so for a 4 burner stove it'd likely add at least $150 to the retail price. The benefit to the consumer is almost nil, so justifying the extra cost and complexity is not worth it.

To the main point, the distinction between forecast and prediction as drawn in my original comment is common within natural hazards risk assessment, e.g., this chapter or this discussion for laypeople with specific application for how we use these terms in the context of earthquakes.

Speaking briefly as a moderator of this subreddit, this comment is rude and unhelpful (and incorrect in context). Please consider our guidelines regarding civility before commenting in the future.

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This was a very masturbatory response. Its wildly over-complicated. Forecast and predict are synonyms, they both infer estimation. You can check a dictionary if you don’t believe me. There is a much more simple straight forward answer to the question here, check my direct reply to the post.

I've actually seen quite a few induction cook-tops that have bang-bang control. Which I don't really understand if they're using switching topologies, like you say. But maybe it's still cheaper to just disable the transistors entirely than to have to design around a variable frequency switching controller?

Thank you for the explanation, I learned something new.

I found a figure that said it took 30,000 years for the first microbes to start showing back up again. That feels weird. Why did the article say that the climate would be returned to normal after 10ish years but it still took 30,000 years for microbe life to return?

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I think you're misinterpreting the article. It mentions that it took a long time for life to come back in the area adjacent or in the crater formed by the impact. That's to be expected, as that area was essentially sterilized by the impact

That that's not what would have happened all over the Earth. If *ALL* the microbes had died, all life would have also died. But we know it didn't. We know that plenty of animals survived the impact and the subsequent climate upheaval. After all, if they hadn't, we wouldn't exist!

So yeah, 10 years sounds like a reasonable figure for the soot and other debris launched into the stratosphere to fall out, and while 30,000 years sounds like a lot of time for life to return to the area of crater, I wouldn't dismiss it out of hand.

Individual main rotor blade angles (pitch) are changed by the swash plate. Tilting the swash plate (cyclic input) creates more lift on one side of the rotor. Raising or lowering the swash plate (collective input) creates more or less lift.

https://youtu.be/HxtXXuMhKKc

https://youtu.be/uVjStAxMFEY

> I notice the recent turkey / Syria quakes occurred on the day of the full moon. Since tidal stresses peak at new and full moons, this seems like an interesting coincidence. Is there any correlation with quake timing and moon phase.

While slightly under the cutoff for the particular analysis in this paper, Hough, 2018 succinctly sums up the extent to which lunar phase has anything to do with earthquakes. As discussed in this paper (with citations to relevant papers), there are a variety of suggestions that there may be real correlations between lunar phase and some details of earthquake statistics in certain magnitude ranges or settings. Importantly though, and especially in the context forecasting, these tend to be global correlations, e.g., for certain earthquakes and certain systems, there might be a slightly higher probability of earthquakes occurring in relation to tidal stresses, but this tells you nothing about specific risk on any specific fault or location so it has pretty minimal utility for actual, meaningful prediction or even contribution to forecasting.

> I’ve previously also seen a study indicating more larger earthquakes occur during a certain phase of a 30 year cycle of earth’s interday rotation time variation. The prediction was more earthquakes would occur in the 5 years following the peak of the variation cycle. The peak was in 2017. Has there been any validation of an increase in large magnitude quakes during the past 5 years?

Without any real detail to go on there, I'm going to guess you're thinking of this paper by Bendick & Bilham, 2017 which was published in 2017, not suggesting a peak in 2017? There has been a follow up in the sense of later papers like Bendick & Mencin, 2020 finding additional support for "synchronization" in global earthquake catalogs. The crucial bit (and this is also discussed in Hough, 2018 more directly) is that generally papers like this are fundamentally misinterpreted by the media and lay audience. Both the Bendick & Bilham and later Bendick & Mencin are pretty explicit about how these observations have very limited utility for earthquake prediction, e.g., from Bendick & Bilham, "Global seismic synchronization has no utility for the precise prediction (in a strict sense) of specific damaging earthquakes" or Bendick & Mencin, "The most notable shortcoming of this outcome is that the empirical synchronization approach provides no useful constraints on the location of events in a developing cluster; they occur globally"

So in the end for both of these types of potential correlations (and any real underlying causation), the extent to which these provide anything actionable is unclear. I.e., does saying that the risk of an earthquake for all places, globally, already at a moderate to high risk for earthquakes are slightly higher on full moons help anything? Is everyone in a seismically active area across the entire globe going to do something different around every full moon as a result based on something like this? Studies like these are useful in the sense of working out all of the myriad controls on aspects of the seismic cycle, but their real world applications in the sense of forecasting are pretty limited.

You're right. For some, the reaction is mild, but for some others it can be dangerous. That's why it requires close medical supervision, in case something goes wrong.

Question for you about factors that contribute to earthquake forecasting. I notice the recent turkey / Syria quakes occurred on the day of the full moon. Since tidal stresses peak at new and full moons, this seems like an interesting coincidence. Is there any correlation with quake timing and moon phase.

I’ve previously also seen a study indicating more larger earthquakes occur during a certain phase of a 30 year cycle of earth’s interday rotation time variation. The prediction was more earthquakes would occur in the 5 years following the peak of the variation cycle. The peak was in 2017. Has there been any validation of an increase in large magnitude quakes during the past 5 years?

To build on this, as people still commonly ask "but surely we can predict earthquakes": even if we had perfect precise knowledge of the stress field in the crust (we don't, it's a rough approximation even with measurements), the literal process of an earthquake is one of fracture and failure.

The difference between fault slip causing a tiny earthquake and a major earthquake is whether the crack/slip propagates or not. And that is entirely dependent on the exact micro and macrostructure of the rock around the initial slippage. Even atomic level imperfections in crystal structure could be the difference in propagation Vs not.

(In fact even the initial slip is determined by the relatively weakest point to accommodate current stress field)

Therefore, to even begin attempting prediction, we need atomic-level understanding of the crust and stress field dozens of km deep. Completely impossible.

hi, follow-up question to help me understand; would another method (using the dimmable light example) be to have several sets of lights at different light intensities and using say a rotary knob pass current to each set of lights to get sort of a stepped change in light?

using the above method could a switch be turned, say 1/8th of the way on, to waste a minor amount of energy to ease the transition between steps?

thanks for the previous answer!

Thanks for taking the time to reply. This is still great to know! I'm glad to know that I'm looking at a scientific-community-wide blank in knowledge, and not just the blank in knowledge of my own research, which sometimes looks identical. Have a great day :)

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There are fully analog ways to get fractional power that don't require a voltage divider. For example, a variable transformer would work just fine in an electric stove. But a variable transformer is also much larger, more expensive, and less efficient than a cheap relay.

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In the simplest sense, you're guaranteed to get a pattern, one that we already know, i.e., seismic hazard is the highest around plate margins. Beyond that, sure, there's been a lot of interest in considering whether various machine learning or AI approaches might have value in forecasting. For example, there's been interest in using such approaches to perform "nowcasting", e.g., Rundle et al., 2022, which is basically trying to leverage ML techniques to figure out where in the seismic cycle we might be for particular areas (and thus improve the temporal resolution of our forecasts, i.e., trying to narrow down how far into the future we might expect a large earthquake on a given system).

Ultimately though, for anyone who's even dabbled with ML approaches (and specifically with supervised learning type approaches which are largely what's relevant for an attempt to forecast something), you'll recognize that the outcomes of these are typically only as good as the training data you can provide and this is where we hit a pretty big stumbling block. We are considering processes that, in many cases, have temporal scales of 100s to 1000s of years at minimum, but may also have significant variations occurring over 100,000s to 1,000,000s of year timescales. In terms of relatively robust and complete datasets from global seismology records, we have maybe 50 years of data. The paleosesimology or archaeoseismology records are important for forecasting, but also very spotty so we are missing huge amounts of detail, such that trying to include them in a training dataset is pretty problematic. Beyond that, there are significant problems generally from the expectation that a method (which is agnostic to the mechanics of a system) will be able to fully extrapolate behaviors based on a super limited training data set.

At the end of the day, sure, you could pump global seismicity into a variety of ML or AI techniques (and people have), but it's problematic to have expectations of reasonable performance of these approaches when you're only able to train such methods with fractions of a percent of the data necessary to adequately characterize the system beyond very specific use cases (like those highlighted above).

For the sake of argument, lets sidestep that we can't effectively induce earthquakes in a controlled sense (i.e., we can't do something that we know for sure that will generate an earthquake of a target magnitude) or that wholesale changing the style of strain release of a given fault zone from something like 1 Mw 8.0 every 100 years to 1 Mw 5.0 every day (which is effectively what you would need to release the same radiated energy of a Mw 8.0 in Mw 5.0 events spread out over 100 years) is impossible.

Let's instead entertain the idea that there is some mechanism to start this process, i.e., we begin chipping away at the stored elastic strain sufficient to generate a Mw 8.0 with a carefully targeted Mw 5.0 event that we some how arrest the rupture of to keep it at a Mw 5.0. What did we accomplish? Well, we released a miniscule fraction of the total radiated energy we need, but we also have now changed the stress state on other parts of the target fault and neighboring faults (and in this, we need to remember that virtually no large fault is a single fault, but a network of faults, i.e., a fault system) through Coulomb stress transfer. So when we move to our next "patch" to try to rupture, the stored strain (and proximity to failure, etc.) will no longer be the same, not to mention we've now loaded adjoining faults, etc. The point being, you can't just have patches of fault fail in a vacuum, each one will impact the state of the system and not always in the direction you want, i.e., an earthquake on one patch can increase the strain on another patch, etc.