related to this topic, here is a very interesting little external combustion engine that runs on the heat from a flame directly (i.e. not a steam engine)
This channel (The Action Lab) is great, it sets an amazingly high standard for clarity of explanation, and for practical combination of experiments and theory, all while being appealing to a broad audience. Most educators would be extremely proud to produce work that's accurate to the standards of a university professor, while remaining appealing to middle-schoolers. I can't imagine what more you want from the content.
he called oxygen the fuel for the fire. the discovery of oxygen was an enormous milestone in the history of science, chemistry, and biology precisely because it's not the fuel for the fire. before that, people knew about fuel, they didn't know about oxygen.
also, he doesn't understand how a bass reflex speaker works. unlike what he said, the port actually decreases the efficiency of the speaker by letting the negative bass note sine waves cancel out the positive sine waves from the front of the speaker, but this is done to tone down the "boominess" of the speaker at its resonant frequency, thus making the speaker more "neutral" sounding, and it's achieved by having the dimensions of the box and the port finely tuned to work most "efficiently" at the resonant frequency.
but in any case, what he says about the "bulk" movement of air (he should probably call it net, i mean all air is bulk by nature) there is no way that the speaker pumping air in and out of the cavity could turn into net movement in one direction. (the smoke ring blower is slowly charged up in one direction, then released in something like an impulse function but loudspeakers don't have that nature) if what he is seeing with his fan-probe is correct, that should have impressed him more and distracted him into studying what exactly was going on (ex: the air coming out was directionally focused from the cone? and sucking back in was amorphous and somehow not detected by his device?) because it is looking for explanation.
tl;dr -- aside from the point about fuel, you mostly don't disagree with him. You have different definitions for the same terms he uses, and you draw your system in a different place than he draws his. Both of you make reasonable choices. A youtube video is not an academic paper, and cannot start by rigorously defining the system under discussion.
> he called oxygen the fuel for the fire... it's not the fuel for the fire
I think you're correct here, from chemistry definitions oxygen is not fuel, because breaking its bond consumes energy rather than releasing it. However, I don't think the host is trying to give perfectly precise chemistry definitions here, he's trying to explain how fire burns, and calling oxygen 'fuel' makes it clear to his audience that oxygen is required for combustion. I think your objection here is similar to objecting that voters in the US elect electors rather than candidates -- it's correct, but not necessary if you're explaining the concept of democracy.
> the port actually decreases the efficiency of the speaker by letting the negative bass note sine waves cancel out the positive sine waves from the front of the speaker, but this is done to tone down the "boominess" of the speaker at its resonant frequency, thus making the speaker more "neutral" sounding
I don't know much about bass reflex speakers, but I read the wikipedia page in decent depth, and it appears to me that you are wrong, or perhaps using a different definition than the field itself uses. From the wiki page: "This port enables the sound from the rear side of the diaphragm to increase the efficiency of the system at low frequencies as compared to a typical sealed- or closed-box loudspeaker or an infinite baffle mounting... Depending on the exact relationship between driver parameters, the enclosure volume (and filling if any), and the tube cross-section and length, the efficiency can be substantially improved over the performance of a similarly sized sealed-box enclosure." [0]. I bet I can see where your disagreement comes from though -- I think you're arguing that adding the reflex speaker cancels some of the power going through the main speaker, and therefore must result in decreased total_power_out/total_power_in (forgive me if I misunderstand). This is a sensible way to define efficiency, and I think you're correct that total_power_out is strictly decreased. However, there are also other sensible ways to define efficiency, eg, instead of total_power_out you might care about the perceptually-weakest frequency the speaker generates, to ensure the sound is "balanced" to a human ear. You might then define efficiency as num_spectral_bins*min_weighted_spectral_power_out/total_power_in. I have some experience optimizing perceived smoothness, and we used a metric very similar to this. Without fully knowing what you mean or what he means, I think you're disagreeing over terms, not correctness.
> but in any case, what he says about the "bulk" movement of air (he should probably call it net, i mean all air is bulk by nature) there is no way that the speaker pumping air in and out of the cavity could turn into net movement in one direction... the air coming out was directionally focused from the cone? and sucking back in was amorphous and somehow not detected by his device?
I think you're agreeing with him here, his explanation matches yours. We can break a full period of oscillation into two sections: a high pressure section (the air molecules being pushed away from the speaker), and a low pressure section (air being pulled back). The high pressure section travels _coherently_ through the air cannon, mostly moving air molecules in a single direction (as you say, it is "directionally focused from the cone"). The low pressure segment pulls air back into the air cannon, but it is _not_ coherent (as you say, it is "amorphous"). During the low section, molecules can flow towards the air cannon from the side of the cannon; they do not have to come from directly in front of the air cannon. If you rewatch that section I think you'll see you're not disagreeing with him. To be fair, more drawings would help communicate it more clearly. You're correct that if you draw your observation box big enough, there can be no net movement from something wiggling back and forth, but I think he's drawing his observation box over the fire. If you look at that system (the air above the fire), you will see net movement.
>I think they intended to continue "... without changing their aspect ratios"
but the context was "see, you can have two different apps running side by side, each with the same aspect ratio as either of the apps when run in the space of the folded screen. not only the same aspect ratio, but the same dimensions"
the whole A3/4/5 scheme is completely overblown as a feature for consumers. You format a document for A4, ok, but you wouldn't print that document A5 because the fonts would be completely shrunken. nobody does that. We use word processors to format documents for the space we have, and we don't ever print wedding invites on A3 or A4
>If you unfold a square, you don't get two squares.
yes, you do. Two squares will fold together into the space of one square, and the same with 2 A4 sheets of paper, or two 8½x11 sheets of paper, two of them will fold together to make one of them.
You said: "If you unfold a square, you don't get two squares."
In the context of this discussion, it is reasonable to assume that any "square" available to be unfolded is something approximately like the folding phone, consisting of two layers joined by a hinge. When you unfold that, you go from having a square to having a rectangle equivalent to two adjacent squares, and usable as two adjacent squares.
I see. I agree (obviously, it's a fact), but in the context of this discussion about aspect ratios and why the golden ratio would be relevant to this situation, it is reasonable to assume that the point here is that a full-screen, unfolded image would scale exactly to a half-screen/folded image with no change in aspect ratio.
> it is reasonable to assume that the point here is that a full-screen, unfolded image would scale exactly to a half-screen/folded image with no change in aspect ratio.
Sure, but aside from being interesting from a mathematical standpoint, there are no practical implications from that fact. When the user unfolds the phone and rotates it by 90 degrees, the fact that they're left with about the same aspect ratio (modulo whatever changes with status bars, etc.) means very little for UI design in light of the much more important fact that the screen doubled in size and thus the application's layout should be using the extra screen space to show more information, and should not assume that a majority of the screen is easily reachable by a thumb.
> None of that matters for a phone.
Of course it does. They show the most basic example right
on the page, which is that you can side-by-side full screen
apps.
which is talking about the case of two separate apps running side-by-side (unfolded), as was shown in one of the pictures of the device.
the stock market goes up and down daily, but with a functioning economy it will overall be up. from a distance you are right, something that keeps going up keeps achieving new highs.
but, if you follow the market on a daily basis, you will be paying attention to the market swooning for periods of time, maybe with a small recovery and then another swoon. New "all time highs" do provide convenient notifications that the economy has now grown from before. Without new highs, your investments are treading water.
>and even the pre- and post-increment operators cleanly lined up with the PDP-11 addressing modes.
pre- and post- increment operators cleanly lined up with... the programmer's conceptualization and objectives--the index is/was frequently used in other contexts than loop bounds and indexing. if that's not your conceptualization, don't use that operator. whether you are on a PDP-11 makes no difference.
and just to make the point more firmly, PDP-11 didn't have a preincrement/postincrement pair of instructions, it simply had indexing with post-increment of the index or pre-decrement, i.e. one paradigm, not two. Or in other words, "stack" behavior.
https://i.4cdn.org/b/1789145070031855.mp4 (completely SFW)
(links to 4chan expire in a day or so, so if anybody has a better link for this, future generations will be able to see it too)
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