renormalizer

@renormalizer@feddit.de

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renormalizer,

You just have to go fast enough. The minimum speed keeping you from falling out of a circular loop is sqrt(gr), with gravitational acceleration g and loop radius r. 10m radius requires 36km/h, which might be suitable for a Jetski. Larger ships need bigger loops to physically fit, and consequently larger speeds. It’s quite surprising, but a monstrous 100m radius loop needs less than 120km/h.

renormalizer,

I think so. At the apex of the loop gravity balances centrifugal force, Fg = Fc, when going the minimal speed necessary to get through the loop. Fg = m g, Fc = m v^2 / r. So mass m drops out of the equation.

renormalizer,

Ein Fliegendes Personenloses Vehikel?

renormalizer,

Der Foxconn-Ansatz ist da günstiger. Einfach Netze um die Dächer von Hochhäusern spannen.

renormalizer, (edited )

youtu.be/-5p7kayK7Pk

renormalizer,

Die Antragstellerin begehrte vor dem Amtsgericht die Feststellung, dass der nunmehrige Beschwerdeführer ihr Vater ist.

Sie mag ihn vielleicht mal “daddy” genannt haben, aber dass das Gericht das so wörtlich nimmt, geht zu weit.

renormalizer,

Ja. Im Verkehrssektor passiert momentan nicht so viel. Tempolimit “will” laut Wissing “niemand”, er reitet das tote Pferd eFuels bis zur Verwesung und blockiert damit eine entschiedene Abkehr vom Verbrennungsmotor, und bei Elektromobilität geht es momentan auch eher schleppend voran. Da könnte der Minister auch mal der deutschen Autoindustrie in den Allerwertesten treten. Die Bahn muss erstmal ihre Strecken auf Vordermann bringen, bevor wir über mehr Güterverkehr auf der Schiene reden können, das Problem hat er aber geerbt.

renormalizer,

Jackie’s arch?

renormalizer, (edited )

IIRC, the first model ate mosfets for breakfast because the photo resistor is way too slow going from illuminated to dark. That leaves the mosfet in a fairly high resistance state for an extended amount of time during which it dissipates a lot of power. You should add some kind of Schmitt trigger inverter that buffers the resistive divider and gives you a clean narrow edge to drive the mosfet gate. A 74HC14 together with a 7805 voltage regulator should give you enough output voltage to drive the mosfet. These chips cost less than a single replacement mosfet and you can drive 6 coils with them.

renormalizer,

And all the gold for his grillz? And the NMR and FTIR machines? Those are at least more broadly useful. Still, looks like he has way too much money on his hands.

Stumped by Heat Pumps? (www.wired.com)

Everyone’s talking about heat pumps these days as a better way to warm your home. They even pull double duty, replacing your air conditioner in summer. The great thing is that they’re generally more energy-efficient than old-school heaters, and they don’t burn any fuel, so replacing that old gas furnace can really shrink...

renormalizer,

The first part of the article triggers me. Heat in the physical sense is thermal energy. Like with other forms of energy, you need an energy difference to actually have it perform work, or you need to invest work to create an energy difference (in a heat engine or a heat pump, respectively). Just like you would letting a weight fall to the ground and lifting it back up. And cooling is removing heat, so ice cubes are actually cooling your drink.

In a pan, low specific heat capacity is not that desirable. That’s why people use big honking chunks of cast iron to prepare food: so adding the cold food doesn’t lower the temperature too much. But the metal also gets you good heat conductivity to quickly get the heat from the stovetop to where it’s needed.

Conversely the handle is made from materials that have low conductivity so heat gets conducted more slowly towards your skin. The higher capacity helps but isn’t that crucial: air has fairly low heat capacity but you can stick your hand into an oven at 100C without getting burned. Unlike boiling water, which has quite a high heat capacity.

The refrigerant should have a high heat capacity to move as much heat as possible for a given temperature difference. Most systems employ a liquid-gas phase change somewhere in the cycle to transfer even more heat energy in the form of latent heat. R134a, a common refrigerant, has a heat capacity about 3/4 of that of water.

One more thing: even if the electrical energy is completely nonrenewable, heat pumps still offer an environmental advantage. Gas power plants are fairly efficient, around 40% of the extractable heat energy gets converted to electricity. With a COP of 2.5, a heat pump would produce as much output as burning the gas in a perfectly efficient furnace. If the COP is larger, the heat pump is more efficient than burning the gas directly, and modern heat pumps usually exceed 2.5 except in the coldest days of winter. Add to that the existence of dual-cycle power plants with 60% efficiency, and the losses of a conventional furnace, and heat pumps may win even on days where the COP is slightly less than 2.

sundray, to comicstrips

@comicstrips "The Came as Decorative Pillows!"

Super-Fun-Pak Comix by Ruben Bolling for February 20, 2024 https://www.gocomics.com/super-fun-pak-comix/2024/02/20

renormalizer,

They’re sofa parasites!

renormalizer,

This was followed by Orandazuma wa Denki Unagi no Yume o Miru ka? (Do Dutch Wives Dream of Electric Eels?, Dec. 1984, PC-8801). Inspired by Philip K. Dick’s Do Androids Dream of Electric Sheep? (1968), players take on the role of a private investigator who has to track down a sex doll (called Dutch wives in Japan) that has become sentient and is murdering its lovers. The player tracks down the rogue doll by seducing all the women in Tokyo’s red-light district.

The concept sounds awesome. The porno parody “Blade Runner” needed.

renormalizer,

Deine gesamte Existenz hängt davon ab, dass der nächste Antrag bewilligt wird und das gibt dir auch nur 2 Jahre Luft. Wenn’s schief geht, brauchst du nicht nur eine neue Stelle, sondern einen neuen Beruf, weil es keine anderen Stellen in deinem Spezialgebiet gibt. Bezahlung ist meistens E13 nach Tarifvertrag der Länder oder TVöD. Davon lässt es sich ganz gut leben, wenn die Stelle Vollzeit ist.

renormalizer,

IIRC from the “What we left behind” documentary, they were shot on film. They even had a few minutes of HD material scanned from the film reels. It’s the CGI that was baked only into the tape version that makes it so difficult to do a HD remaster. And why they went back to the tapes when producing the DVD release.

renormalizer,

Sie haben Newag falsch geschrieben.

renormalizer, (edited )

Wie schon ein altes hessisches Sprichwort sagt:

Was geht ab? Wasserfab. Was bleibt dran? Edding, mann.

renormalizer,

Nach manchem Arbeitstag fühle ich mich, als ob mir mit dem Arbeitstag eins übergebraten wurde.

renormalizer,

What is meant here, I believe, is (1 - Int)^-1. Writing 1/(1 - Int) is an abuse of notation, especially when the numerator isn’t just 1 but another operator, which loses the distinction between a left and a right inverse. But for a bounded linear operator on a normed vector space, and I think Int over an appropriately chosen space of functions qualifies, (1 - Int)^-1 equals the Neumann series \sum_k=0^∞ Int^k, exactly as in the derivation.

Int is injective: Take Int f = Int g, apply the derivative, and the fundamental theorem gives you f = g. I think you can make it bijective by working with equivalence classes of functions that differ only by a constant.

renormalizer,

Sets of measure zero are unfair. But you’re right, the second line in the image is basically an eigenvector equation for Int and eigenvalue 1, where the whole point is that there is a subspace that is mapped to zero by the operator.

I’m still curious if one could make this work. This looks similar to problems encountered in perturbation theory, when you look for eigenvectors of an operator related to one where you have the spectrum.

renormalizer,

Leider nicht im kleineren Segment. Der Peugeot e208 ist gegenüber Ende '21 knapp 20% teurer geworden – zumindest in der hohen Ausstattung. Damals 36k für GT+Sitzheizung, heute 42k für die vergleichbare Konfiguration GT mit 100kW und 50kWh+ACC+Sitzheizung+11kW AC-Laden, die alle nicht mehr Serie sind. Und damals gab’s noch knapp 10k Förderung. Vergleichbare Id3-Konfigurationen lagen damals 2-3k drüber, die Differenz ist heute im Wesentlichen gleich. Da bewegt sich momentan alles in die falsche Richtung.

renormalizer,

Especially when you don’t have a US keyboard. How the fuck am I supposed to navigate through the info document when the key combination to follow links is Ctrl+] and ] itself is hidden behind some modifier combo?

renormalizer,

Offensichtlich gehören Texteditoren jetzt auch zu diesen Hacking-Tools. Anzeige gegen Microsoft wegen notepad ist raus?

renormalizer,

xkcd 830

renormalizer,

Kannst du jetzt ohne Fallschirm aus dem Flugzeug springen? Ist ja noch kein Meister vom Himmel gefallen.

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