7 ms·
The fact that the telescope's cryocooler is acoustically symmetrical such that any vibrations made by each cylinder, and the actual flow of gas, is near-perfect
by ResNet 4y ago
The fact that the telescope's cryocooler is acoustically symmetrical such that any vibrations made by each cylinder, and the actual flow of gas, is near-perfectly cancelled out is nothing short of amazing. [0]
Real Engineering made a video that covered this and more, which is well worth a watch. [1]
[0] https://webb.nasa.gov/content/about/innovations/cryocooler.html https://webb.nasa.gov/content/about/innovations/cryocooler.h...
[1] https://www.youtube.com/watch?v=aICaAEXDJQQ https://www.youtube.com/watch?v=aICaAEXDJQQ (The Insane Engineering of James Webb Telescope)
- Diederich 4y agoYup, pretty much everything on this guy's channel is top drawer.
- dralley 4y agoHe's pretty good but perhaps not very critical. I'm not sure that's necessary for the types of videos he produces but the ones about the Boeing 787 and especially Nikola seem a bit flowery given everything else we know about them.
- mardifoufs 4y agoI mean a part from some teething flaws, the 787 is still an incredible plane. Brand new types are rarely introduced and they almost always have some issues early on.
- bXVsbGVy 4y agoThe Launch Pad Astronomy is another great source for astronomic content [1]. I found pretty awesome the live show about JWST done with NASA scientists [2]. [1] https://www.youtube.com/c/ChristianReady https://www.youtube.com/c/ChristianReady [2] https://www.youtube.com/watch?v=Xv7QiNjx_MY https://www.youtube.com/watch?v=Xv7QiNjx_MY
- neb_b 4y agoSmarterEveryDay also has a really interesting episode about the sun shield https://www.youtube.com/watch?v=Pu97IiO_yDI https://www.youtube.com/watch?v=Pu97IiO_yDI
- mywacaday 4y agoThis video https://youtu.be/5MxH1sfJLBQ https://youtu.be/5MxH1sfJLBQ was posted here https://news.ycombinator.com/item?id=30729109 https://news.ycombinator.com/item?id=30729109 about how the actuators work on the James Webb telescope. It's a great watch.
- dav_Oz 4y agoRobert Warden (original author of the paper "Cryogenic nano-actuator" (2006)[0]) did the first prototyping with Lego Technic [1]. From Lego to the JWST, I mean damn, like childhood dreams come true (: [0]https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden.pdf https://www.esmats.eu/amspapers/pastpapers/pdfs/2006/warden.... [1]https://m.youtube.com/watch?v=3WBrqUa_1yk https://m.youtube.com/watch?v=3WBrqUa_1yk
- beambot 4y agoI'm having a hard time understanding the axial motion from the coarse adjustment. From [0]: The Ball Screw in Figure 9 has a 21 mm range. As the ball screw nut moves up, the housing moves up too -- but then the two halves of the tumbler coupling get displaced in such a way that doesn't seem to support a 21mm displacement. How does the tumbler coupling stay mated? (I feel like I'm missing something obvious?)
- phinnaeus 4y agoWhy are you supposing that the two halves of the coupler are moving apart? They are both attached to the moving section
- beambot 4y agoFigure 9 implies that the coupler drives the blue gear (shaft of lead screw). But let's assume you are right: Then how does the blue gear at top of the lead screw simultaneously turn the shaft and move upwards too?
- 4y ago
- AceJohnny2 4y agoMotorcycles have a similar constraint, so I'm a little blasé on the technique.
- throwthere 4y agoKind of like a flat four or six engine versus inline/V6.
- red369 4y agoFlat fours and sixes definitely have a balance advantage over V6 engines, but I’m not sure there is much difference to a straight (in-line) four or six. They are also perfectly balanced until some higher order harmonic (something I can’t really remember at the moment). The advantage of flat engines are that they are much shorter, but then they’re heavier and more complicated because they have to have two heads. (Edited a typo in first sentence)
- t0mas88 4y agoThe 6 in-line is the least vibrating one of the options, but the 4 is very close.
- red369 4y agoWere you including flat engines in that statement? Like, an online 6 is better balanced than a flat 6? If not, do you happen to know how a flat 6 compared with an inline 6 for vibrations/balance? A quick search didn’t find me anything. I know flat engines have to offset the cylinders a little.
- nickff 4y agoInline sixes are better-balanced than flat sixes.
- roamerz 4y agoNot necessarily. If memory serves GM had a V6 in the 70’s or 80’s that had offset crank journals to make each firing stroke 120 degrees apart. I think it was the 4.3
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- _fizz_buzz_ 4y agoThis is the kind of thing I would never come up with and if I did I would never think it would be possible to implement. There are some seriously ingenious people out there.
- sslayer 4y agoTeams, seriously ingenious teams.
- pmcp 4y ago
- effingwewt 4y agoDiversity has nothing to do with anything here, the team could very well be entirely homogeneous. In this context, I'd say intelligence of said team matters, not their gender or race.
- interroboink 4y agoI can't speak for the person you replied to, but my interpretation was "diversity of minds" (or "viewpoints", etc), not gender or race. Perhaps you'd agree that the diversity of opinions and points of view on a team is crucial, even if they're all X race Y gender.
- birdyrooster 4y agoThat’s the whole point of diversity being a blind spot, because intelligence isn’t some integer value.
- inopinatus 4y agoThere is a good case for holding diverse hiring practices in high esteem: * Heterogeneity of ideas is moderately correlated to diversity of backgrounds * Diverse teams are less prone to groupthink, more ready to acknowledge and correct for their biases, and they more readily challenge one another on a factual basis * Hiring practices that try to offset structural biases and personal tendencies towards uniformity can access talent pools that others do not To sum up, disregarding any political or social viewpoint, diversity is a strong value driver. As for "intelligence", whatever that is; insofar as it can even be qualified, let alone quantified, this remains a minimal contributor to performance beyond the second sigma. Genius is contextual. Source: me, have joined/managed high performance tech-sector teams, including extraordinary individuals from unusual/outlier backgrounds.
- sacrosancty 4y agoI have a feeling that a huge amount of common engineering ideas that we all see as common sense, like gears, linkages, pistons, even the wheel, would have been beyond the imagination of most people before they were invented. I'd say we only know them because we've seen them. This other stuff might be common knowledge among specialists in that field, or not.
- ramraj07 4y agoThat’s the beauty of technology though. Once someone figures out something, no matter how inexplicable, the mere suggestion of the possibility is enough to propagate a new normal where everyone assumes it’s pedestrianness. The atom bomb, nuclear power, iPhones , the list is endless indeed.
- XorNot 4y agoThe Road Not Taken[1] short story tends to stick in my mind because of that. There's a lot of ideas that are extremely obvious once you see them, but without the prompt you might never get there. [1] https://eyeofmidas.com/scifi/Turtledove_RoadNotTaken.pdf https://eyeofmidas.com/scifi/Turtledove_RoadNotTaken.pdf
- akira2501 4y agoThat's where I really love James Burke's "Connections" TV series, it somewhat dispels this idea by showing just how interconnected discoveries and inventions were even in a far earlier age. One invention makes a new way of making money possible, this new way of making money comes with entirely new challenges and the capital to solve them. Unsurprisingly people naturally align themselves to solve these problems and capture some of that capital. The idea of the "lone inventor" is a lovely one.. but I submit that they have not been the majority of force behind much of the invention our world now enjoys. Humanity itself is an iterative process.
- sacrosancty 4y agoOh, I agree. I'm not saying nobody else would have invented them, but I think you'd have to put some expensive work into inventing even a wheel, not just causally imagine it whenever the need came up like we would do today. A lot of technology is really ingenious but it would surely have been invented by somebody the moment it became economically valuable to do so.
- JohnBooty 4y agoOn a much less impressive (though more acccessible, at least for those of us who don't get to tool around with space telescopes on a regular basis) a similar technique is actually pretty common in consumer audio applications. A number of Apple devices employ this technique, like the new iMacs. I know the 2019 (and presumably, the 2021) 16" MBPs do: https://thenextweb.com/news/the-new-imacs-have-force-canceling-speakers-heres-what-that-means https://thenextweb.com/news/the-new-imacs-have-force-canceli... It's popular in higher-end subwoofers. While not the cheapest solution, a whole host of design issues is solved by simply adding a second amplifier and a second driver firing in the other direction. https://us.kef.com/kf92-subwoofer.html https://us.kef.com/kf92-subwoofer.html If I'm not mistaken a fair number of portable Bluetooth speakers use something similar. If you're hearing a surprising amount of rattle-free bass come from a device that seems too small to pull it off, there's a decent chance they're using dual opposed drivers.
- grishka 4y agoDo they use this in the 2021 MacBooks too? The thing sounds almost like it should not be physically possible to pack this much bass into such a thin device. p.s. I'm so tired of random websites blocking Russian IPs because reasons
- Cthulhu_ 4y agoI've blocked Russian IPs from my website because the vast majority of spambots had a Russian IP. Anyway yeah, I was already impressed with these little portable speakers.
- JohnBooty 4y agoYeah, it seems the 2021 MBPs use a similar system: "A high-fidelity six-speaker sound system features two tweeters for a clearer soundstage and four force-cancelling woofers, resulting in 80 percent more bass" https://www.apple.com/newsroom/2021/10/apple-unveils-game-changing-macbook-pro/ https://www.apple.com/newsroom/2021/10/apple-unveils-game-ch... I'm not sure what this "80% more bass" claim is in comparison to. But the 2019 models are definitely impressive. I'm looking forward to hearing the 2021 at some point.
- goldphotograph1 4y ago