All of Eggrenade's Comments + Replies

You're making assumptions beyond the problem statement.  The problem never says pressure is constant, so a temperature change does not imply a change in volume.  (An inferred change in particle number could also change the density, but I'm guessing that wasn't your mistake.)

Wouldn't simply banning TikTok constitute a bill of attainder?

3JenniferRM
The plan I'd aim for would be media regulation, not consumer regulation.  The right of a "free press" implies that the people who are operating the press are free from tyrannical governments and applying their conscience to their public contribution to the marketplace of ideas. However, Jack Ma was missing and maybe-dead for a long time, and the people running TikTok are under the same unelected authoritarian genocidal government that Jack Ma was under. The only way such business leaders can resist pressures to comply with Xi's whims are for a short period of time, up until they are tortured or murdered or have their company stolen from them or whatever, and somehow replaced with anyone more compliant. I'm not saying the oligarchs in this case are morally bad, just that their moral goodness could not possibly be expressed if it was vetoed by their structurally tyrannical ruler. Indeed, my respect and care for Jack Ma, as a person, grew when I found out he was handled so brutally by his own leaders. The people who run ByteDance surely know that similar things can happen to them. So I'd say that there are probably numbers, F, M, W, where it would be good to assess fines of $F per day to any media companies that implement recommendation engines that with more than M% market penetration in the US, who are more than W% owned by (or have anyone in their C-suite or board of directors) who is living without rights or elected leaders. It is pretty simple: in the free world, the companies that critically rely on freedom to function should be owned and operated by free people.

Did you send this to the authors?  Most academics would jump at a simple tweak for a new publication.

6jefftk
Yup! Sent them an email with a short summary and a link.

Doing this can send out a jet of air above your thumbs.  If you send this jet into your mouth, you can change the pitch by changing the shape of your mouth, which I found endlessly amusing as a kid.

Answer by Eggrenade*54

Linus Tech Tips has a secret shopper series where they (anonymously) order several prebuilts and test them out.  They find that they vary greatly in quality, with Dell (which owns Alienware) being the absolute worst.  iBUYPOWER takes the prize, with boutique brands Maingear and Origin PC doing well, but you will pay a price premium.

Gamers Nexus also reviews some prebuilts and finds a lot of them horrifically terrible, especially Alienware.  Like, really, it's not that hard to build your own PC; how can these prebuilts be so incredibly incomp... (read more)

1Rudi C
Considering that DIY is widely acknowledged to be viable, my prior is that the marketing around Alienware is bullshit and it’s just fine. Care to point to hard data that refutes this?

An unconditional right to bodily autonomy also implies the right to prostitute yourself and sell your organs, not to mention try whatever drugs you want or purchase corrective eyewear.

Measuring energy consumption is cheap and easy with a $30 Kill-a-Watt: https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU/ref=sr_1_3?crid=2F9E51CGW3ZDS&keywords=kill+a+watt&qid=1656014636&sprefix=kill+a+watt%2Caps%2C107&sr=8-3

I propose a follow-up experiment to measure daily energy consumption alternating hose configuration with the same set temperature.  The previous experiment tried to answer "how much does maximum cooling power change between configurations," while here we would answer "how much does efficiency ... (read more)

I'm not so sure a central air system wouldn't be up to the task.  I calculate this purifier at 150 CFM from the product page and assuming 8 ft. ceilings, and this implies 1,500 CFM would be a fairly typical residential HVAC system, so that seems roughly adequate to me.

Also, that product page suggests you should cycle air 5 times per hour, but that seems excessive to me.  I use that unit in a much larger room on a low setting and it does just fine getting rid of any smoke smell from wildfires.

2jefftk
microcovid.org thinks outside is 1/20 the risk of inside, and 5 ACH gets you to 1/4. The purifier you link to has a CADR of 141 CFM, so roughly equivalent to bringing in outside air at a rate of 141 CFM. If your residential system can do 1,500 CFM on a 2,000 sqft house with 8ft ceilings, I get 5.6 ACH. That's quite a bit better than I expected; not sure how typical that is?

Though I love the idea of a filtered ceiling fan that's out of my way and can therefore be larger and quieter, I don't think a jury-rigged solution would work at all.  Fans tradeoff flow for static pressure (https://blog.orientalmotor.com/fan-basics-air-flow-static-pressure-impedance), and I'd bet ceiling fans are optimized for flow.  The filters will up the impedance considerably compared to basically open air, and the flow would drop dramatically.

 

Also, some (most? all?) central air systems can run fan-only (no heat or AC), making additional filters unnecessary.

2jefftk
Box fans are also optimized for flow, but do well when used as filter cubes. Part of this is that these filters do not actually offer very much resistance to flow. A central air system is generally not spec'd to move a large amount of air: they usually work by moving a smaller amount of more conditioned air.

I would not have predicted that.  I don't think I've ever seen a power brick not rated for multiple voltages.  If I ever find one, the first thing I would do the next time I'm in a 240V country is plug it in and see what happens, but please don't do that yourself unless you know what you're doing.

3jefftk
It's the first power brick in this post, above. We did plug it in, by accident, and ruined it.

One of my TVs is rated to work anywhere, and another is not.  All my computer monitors are rated for multiple voltages.  For my TV that's rated 120V only, I think it's intentionally not certified for 240V because it's an NTSC model.  There might be a fuse set to blow if you plug it in to 240V, but if not, I would be only mildly surprised if it just worked.

Your heuristic is accurate, but I think understanding why it is accurate is as easy as remembering the heuristic.

The near-universal switched-mode power supply works efficiently for a broad range of input voltages and frequencies.  If your device runs on DC, with very rare exceptions (some high-end audiophile gear, specialized equipment), it has one of these AC/DC converters (power brick, wall wart) and can run on the mains power anywhere in the world.

All electronics run on DC.  Anything with a large motor (not the motor for your optical drive tra... (read more)

3jefftk
A counterexample: our baby monitors run on DC and use external switched-mode power supplies, but only take 120V.
3philh
Hm, from your explanation I'd expect TVs to work anywhere, but Jeff's heuristic mentions them as not?

Russia attacking the rest of Ukraine may be a tactic to keep Ukraine from concentrating it's forces in the east, rather than an attempt to take significant territory.  It's still possible Russia will stop and consolidate gains after taking a chunk of the east (like in Georgia and Crimea).

Occupying Kiev is the kind of thing where cheap weapons (missiles) can destroy expensive weapons (tanks), and is probably very undesirable, depending on how many of those cheap weapons have gotten and will get to Ukrainians.  It might be possible to install a puppet government with minimal losses, though.

I would love an elaborate collector's edition box set for my coffee table when all six books are revised. The version on my phone is the one I'm actually going to read, but this is the kind of thing I want friends to see in my apartment when they visit.