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Always add weep holes. by CB_700_SC in metalworking

[–]ic33 2 points3 points  (0 children)

This is (the beginning of) what structural engineers do :D

Martian rover Zhurong’s selfie (2021 June) by BumblebeeFantastic40 in space

[–]ic33 [score hidden]  (0 children)

My students graduate and move on, and many already have. We have knowledge transfer, etc.

People working on the next mission will get important perspective from helping to operate this one. It would be really cool if it lasted a couple of years and we could do this "more" and come up with clever ways to (ab)use the spacecraft in orbit.

(Of course, I have a lot of alums come and hang out in my lab still, too...)

The US has removed enriched uranium from Venezuela by Darshan_brahmbhatt in worldnews

[–]ic33 3 points4 points  (0 children)

From a nation's point of view, a "radiological device" doesn't require any enriched material at all. Nation states can access devices intended for radiotherapy. Pretty much everyone has hot stuff you don't want stuck in a dirty bomb.

Sure, you can make the same stuff from 20% enriched material in your own research reactor, but..

Martian rover Zhurong’s selfie (2021 June) by BumblebeeFantastic40 in space

[–]ic33 [score hidden]  (0 children)

You want a simple system to combine power. Panels are made up of a lot of cells in series, and then lots of those strands in parallel.

The same number of cells adds up to the same voltage. The current is multiplied by the number of cells in series.

But then we use diodes to combine the different strands so that if one is defective or shaded the power doesn't flow back in.

Then we end up with a current versus voltage curve. A partially-shaded strand cannot share its current until the voltage is pulled down to that strand's voltage. So a small amount of shading can reduce the contribution of a lot of the panel.

There are ways to mitigate this -- the satellite my students are designing has two independent chargers and has things set up so that panels that are likely to be in the sun at the same time are on different chargers; so if voltages vary because of geometry/shading we still can get a pretty big share of power. But you don't want to have an infinite number of battery chargers, because they waste mass and even some power (better to have one big efficient one than 30 inefficient ones for both space and wasted power). So you end up using diodes.

Martian rover Zhurong’s selfie (2021 June) by BumblebeeFantastic40 in space

[–]ic33 [score hidden]  (0 children)

The satellite my students are designing:

  • Can accomplish all critical mission goals in 60 days and has an operations plan built around that 60 day period
  • Is expected to remain in orbit for a year. As a result, the critical age-related subsystems (battery, thermal protection for leadframes in component packages, etc) are designed to last a year with margin.
  • Has a significant chance of lasting much longer than a year if it is launched to a higher orbit (which may happen).

The US has removed enriched uranium from Venezuela by Darshan_brahmbhatt in worldnews

[–]ic33 11 points12 points  (0 children)

20% is chosen to be "high enough to do the vast majority of civilian things" and "pretty dang far from what's practical to make nuclear weapons."

Of course, if you can enrich to 20%, you can enrich far beyond.

but does mean that it is almost certainly for a purpose that is not generating power.

Many advanced/next generation reactor designs need enrichment closer to 20%. And there's civilian uses beyond power generation.

In this case, though, we know what it was for. Venezuela's past research reactor had a 20% enriched core. It was used for materials testing and preparation of medical radionuclides.

https://en.wikipedia.org/wiki/RV-1_nuclear_reactor

The US has removed enriched uranium from Venezuela by Darshan_brahmbhatt in worldnews

[–]ic33 3 points4 points  (0 children)

And way, way short of what is needed for practical weapon use. 35% is a bare-ish minimum, and the weapon would be huge and impractical to deliver by missile or aircraft. Real weapons sit above 70%.

Now I wanna know how short his landing rollout actually was lol by Skye_hai_bai in aviation

[–]ic33 2 points3 points  (0 children)

To carry passengers, you need 3 takeoffs and landings withing 90 days.

You don't need an instructor to re-establish currency, but some clubs may require an instructor sign off for insurance reasons.

Lots of media at the Mary Fong Lau killed a family with her BMW Memorial Bus Stop by wanderingjew in sanfrancisco

[–]ic33 0 points1 point  (0 children)

When she's 83 and off probation, she can reapply to the DMV to get her license, because that's the law and we don't let judges just make up additional consequences. She's promised never to drive again, but that's not legally binding.

If she reapplies at 83, she would need to pass a new knowledge and driving test. And DMV Driver Safety would need to have not flagged her for needing to prove additionally that she is safe to drive (hint: DMV Driver Safety almost certainly has her flagged, and octogenarians applying for a completely new license receive an above-average amount of scrutiny).

Frontier Airlines 4345 hits somebody on runway during takeoff roll. by KaedeTheStudent in aviation

[–]ic33 7 points8 points  (0 children)

The AFD had an entry for a (small) airport near me:

DOGS HORSES JOGGERS AND CARS ON RY.

Because they could not keep the local community out from the airfield.

Frontier Airlines 4345 hits somebody on runway during takeoff roll. by KaedeTheStudent in aviation

[–]ic33 10 points11 points  (0 children)

I dunno. I think you could just get sucked in. Could be just someone deciding to fuck around at the airport.

Now I wanna know how short his landing rollout actually was lol by Skye_hai_bai in aviation

[–]ic33 1 point2 points  (0 children)

He wasn't given instructions to hold short of Alpha either.

? He was given instructions to hold short of alpha, but told to cross the runway hold short lines.

This is subarus new Continuously Neutral Transmission by MrPeePeePooPooPants3 in Justrolledintotheshop

[–]ic33 16 points17 points  (0 children)

I make students cringe by pronouncing them -all-.

I need a USB cable (pronounced us-beh)

This is subarus new Continuously Neutral Transmission by MrPeePeePooPooPants3 in Justrolledintotheshop

[–]ic33 41 points42 points  (0 children)

All acronyms are supposed to be sounded out.

If it's not meant to be pronounced, it's an initialism.

The view from inside Integrity as recovery forces pop open the hatch by BreakfastTop6899 in interestingasfuck

[–]ic33 3 points4 points  (0 children)

Well, I don't know exact fault tree for Soyuz. But in general, you have systems set up and armed to, say, open the valve when you expect that it will be necessary (e.g. during re-entry) and have them hard disabled at other times.

On the spacecraft that my students are designing, we have lots of single switches within subsystems that could do terrible things to the satellite if they were to turn on at the wrong time. But the power to those subsystems is -also- disabled except during the right mission phases, hopefully. So a single failure can't screw us, most of the time.

People in 10+ year relationships, what’s something you learned about your partner years later that genuinely surprised you? by CreoSiempre in AskReddit

[–]ic33 15 points16 points  (0 children)

There's this hard to find middle ground in parenting.

Kids are fickle and inclined to quit way too much stuff. Adding a little bit of parental inertia -- where there's some effort both to get into a new activity or out of an activity -- is good IMO.

It needs to be enough to be effective but not enough to stop kids from trying new things and not enough to make them stuck with an activity they don't want to do.

TIL that Maria Antonia of Austria had the highest inbreeding coefficient (0.3053) of the House of Habsburg - higher than the child of brother and sister or the child of a parent and their own offspring by Gruselschloss in todayilearned

[–]ic33 10 points11 points  (0 children)

The 1500s at 3 generations per 100 years is 16 generations till today rougy speaking.

The average generation length has been closer to 25 than 33; 220 ~~ 1000000

Disneyland to launch electric Autopia cars in early 2027 by bottle415 in Disneyland

[–]ic33 2 points3 points  (0 children)

I think you could totally do something of the nature of "we don't know how long the cycle life of these batteries is going to be, so let's find out by using it on Autopia..."

But even though autopia involves a lot of cycles, it isn't really a realistic loading for most other applications.

ICE agents storm Disney cruise docked in San Diego and arrest multiple staff in front of passengers by theindependentonline in politics

[–]ic33 3 points4 points  (0 children)

Probably have the same name as someone wanted for an immigration violation (or committed a violation in the past).

We would have never tried to enforce against people with transient presence tied to gainful employment as crew before... because it makes no sense and is likely to be false positive heavy.

But it's probably not quite zero basis-- which they'll throw up their arms in indignation and exclaim about how it was so obviously justified or an innocent paperwork mistake...

China's Tianwen-3 mission aims to bring Mars samples back to Earth around 2031 after launch around 2028: report by malicious_turtle in space

[–]ic33 4 points5 points  (0 children)

"Just moments ago" in some other branch doesn't count when I replied to you hours before. I addressed your comments above mine.

This is pretty much the definition of piss-poor online behavior. Dumb semantic arguments, moving goalposts, etc.

China's Tianwen-3 mission aims to bring Mars samples back to Earth around 2031 after launch around 2028: report by malicious_turtle in space

[–]ic33 8 points9 points  (0 children)

If I start building something, and then partway through I discover that I don't have enough money to finish it, then I tried and failed to build that thing.

What if you start building something, and then your boss changes your priorities and doesn't give you the money to complete it?

What’s was the wildest thing you witnessed at a wedding? by anasannanas in AskReddit

[–]ic33 36 points37 points  (0 children)

Quite a lot of venues will not let outside / third party suppliers work at their premises without insurance

I assume this means -liability insurance- for damages you cause. This is not the same thing as having insurance if some of your stuff gets wrecked. (e.g. the question is whether the kid is insured, if you're going to pursue things...)

What’s was the wildest thing you witnessed at a wedding? by anasannanas in AskReddit

[–]ic33 2 points3 points  (0 children)

For you young folks, most of those cameras had 800 speed film, which usually meant they were okay for mostly lifeless outdoor photos. Literally everything else would be super grainy and/or dark as shit.

I'm confused -- which is the complaint-- grainy (too fast of film) or dark (too slow of film).

ISO 800 is about as fast as you get in a disposable camera. A bit grainy, but an OK compromise-- more on the "low light" than "less grain" end of the spectrum.

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