I was a small child at the zoo. I had lost my parents in the crowd, and was scared.
A nice black man (this was important because I grew up in a white neighborhood and hadn't encountered many black people before) knelt down to me and asked me if I was okay, if I was lost. They brought me to the zoo office where they called my parents.
I'll never forget how strange and different they were to the child me, and yet how kind they were in the sea of scary strangers.
Houses are physical objects. If you take it someone else has to lose it. E-Books are digital objects. You can have infinitely many copies of them without anyone losing anything.
And yes, DRM infringes on essential rights, it not only limits what you can do with something you supposedly bought, but takes away your control over your own hardware.
And even more basic is the right not to get frauded. If someone claims to be selling something to you, but then they only give you locked down, perhaps even revokable access to it, then they are defrauding you.
Many hosts consider anyone entering the unit , even just for lunch or dinner, to count against the listing "max", and accuse you of having a party. and some are quite big brotherish about monitoring.
Last month a first time host confabulated $1200 of maintenance charges. Having left the property already, I was in no position to produce evidence that they were fake. Arbitration was hopeless, I canceled my card and won't be using Airbnb again.
Funnily enough I went through something similar 3 weeks ago at an Airbnb in France.
The host retaliated because we had the audacity to tell her that the place was unclean when we checked in. She claimed 2000$ of fabricated damage and as you Airbnb sided with the host initially.
It's only because I lost 3 hours of my time with support and took a thousands of screenshot from our Messages that I got them to drop that charge.
I also issued a Chargeback with my credit card for the dirty place.
But yeah, this is done for me as well. I had 20+ stays but I will never , absolutely never use them again. My time is worth something and this Airbnb destroyed our holiday and took way too much of my time to handle.
same. and when I learned it was Dan G I didn't accept it entirely. now it's a sort of superposition of them - and mostly a nebulous entity that maintains civil discourse - like something from a Miyazaki movie
The blades are hollow and have air injected from where they attach to the outside edge and fin of the blade, so when it’s spinning the blade doesn’t contact the exhaust stream because it’s coated with a layer of relatively cold air. Same thing happens with your car pistons but using an inertial layer.
Image search for a turbine blade and you’ll understand as soon as you see it.
The reason you can’t shut the engine down or power off suddenly is because the blades and housing cool at different speeds, the clearance between the blade tips and housing is as close as possible.
To help with this, hot air from the turbine is sprayed onto the outside of the casing via a hot bleed air bypass when the ecm determines its necessary.
If you shut down suddenly the tips of the blades can contact the housing and best case rub, worst case break.
There’s another problem along these lines which really exemplifies how tight these tolerances are, on the a320, you need to do a bowed rotor procedure if you’ve been sitting with the engines off for 45 minutes before you restart. This involves turning the engine over with the apu to equalize the cooling throughout the engine because the core of the engine cools slower but there’s two shafts running through the middle. These shafts “bend” because the outside is cold but the middle is hot, they can then rub against each other ruining bearings etc.
Your china charger doesn't have clearances that tight.
Turbo timers are a legacy from the days when turbos were primarily oil cooled and synthetic oil wasn't common and shutting down a glowing hot turbo would tend to create sludge if done habitually.
This is amazing yet again that they can ingest rain and snow so the inside can be, what, close to 3000F yet you can come into land in Minneapolis when it's -30F and everything Just Works. Imagine how different aviation would be if in an alternate universe we had modern jet engines but under no circumstances could they ingest water?
Note that at cruising altitude it would be more like -80F. The engine would be more efficient at sea level at -30F as the mass flow rate would be higher. Ingesting water vapour actually improves things for the same reason. The downside is it can cause corrosion over time.
> What do you mean by "metals don't actually withstand temperature"? As in the raw metal would melt were it not for the cooling vanes?
Metals don't need to melt to fail. Increasing the temperature leads to gradual reduction of yields limits. For example, the yield stress of steel drops to 50% if it reaches around 500 degrees.
but also yes, the metal would melt if it somehow managed to not fail. Often the turbine blades are operating in an environment above their melting point and only don't melt because of the internal cooling.
> What do you mean by "metals don't actually withstand temperature"? As in the raw metal would melt were it not for the cooling vanes?
A small addition to the sibling comments: Combustion temperatures in modern turbines are around 1400C, if I recall correctly, but the best nickel superalloys go up to 1050C or thereabouts (for long-term operation). To close this gap, the use of high-temperature alloys is supplemented with active cooling and ceramic coatings, as stated by GP.
> What do you mean by "metals don't actually withstand temperature"? As in the raw metal would melt were it not for the cooling vanes?
They creep. Have you seen, for instance, Blu-tac or glue fail? It doesn't go at once, but slowly, over a period of time. At high temperatures most metals (others on this thread have mentioned single-crystal blades) behave a bit like that.
Although steel is also weaker at temperatures far below its melting point, yes. A simple observation of a blacksmith at work should tell you that. And a think some new jets may be running hotter than Tm for steel now?
> The lower power setting on shutdown does what? Spin it at a low RPM so it doesn't decrease in temp too quickly?
Yup, or more relevantly evenly, although those tend to be related. Given almost all materials expand as they get hotter and contract as they cool, different cooling rates between parts -> different contraction rates -> different relative shape -> Very Bad in precision machinery.
So basically metal gets rubbery when hot, and stopping something all off a sudden could have inertial forces(moving blades, gears etc) wreck the structure?
You have to shut things down step by step, so that rigidity is supplied to the metals as the inertial forces are reduced.
A nice black man (this was important because I grew up in a white neighborhood and hadn't encountered many black people before) knelt down to me and asked me if I was okay, if I was lost. They brought me to the zoo office where they called my parents.
I'll never forget how strange and different they were to the child me, and yet how kind they were in the sea of scary strangers.