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Show HN: Elevators

john.fun

351–360 of 426 posts

Re: Show HN: Elevators

#351

Earlier quoted context omitted.

I wonder if we'll see LLM elevator scheduling

I apologize for bringing you to the 29th floor instead of the 3rd floor as you requested. That's on me. I will do better next time.

I want to own something here: this is the fourth time in a row I’ve brought you to the 29th floor when you asked for the third. I am creating a memory to always go to the 3rd floor instead of the 29th, which should prevent this from happening again.

Re: Show HN: Elevators

#352
post #296

Earlier quoted context omitted.

I don't understand why the fact that it's an Airbnb really matters here? Unless a large number of apartments are meant to be empty, why does it matter if the tenant is short term or long term? Is it that short term users leave and enter their apartment more often?

I am of course just speculating (and I had a lot of waiting time to think about this), but there are a lot of people with a lot of luggage constantly going in and out. It makes the elevators be full faster (perhaps there is a weight based sensor to determine if the elevator is full, and the luggage tricks the system into thinking the elevator is not full yet, because a piece of luggage is lighter than a person but so…

Amusing anecdotes and musings about your stay (well, amusing to read, probably not to live).

Since you’ve got a bunch of enforced idle time, maybe see if you can find the architect firm and see if you can get the backstory? Why three elevators in a 60 floor building? Just low level sadism, or what?

Re: Show HN: Elevators

#353
The worst situation I've encountered is after a large conference when everyone is leaving the hotel at once. An elevator quickly fills up on the way down, but then wastes time stopping at every subsequent floor with a call, even though no one else can fit inside. At each floor the elevator stops, the doors open, the waiting people see it's already packed, the doors close, and this repeats on the next 15 floors before finally reaching the bottom where everyone gets off. If the algorithm could know an elevator is completely full and only stop at its destination floors rather than every floor along the way with a call, it would be far more efficient.

Re: Show HN: Elevators

#354
post #65

Earlier quoted context omitted.

I've never seen anyone do this anywhere in the world including Italy. I've never been to China but wouldn't you learn quickly after getting in an elevator going the wrong way not to do that again? The only exception I can see if there's way more people than elevators and you just need to get spot at all costs.

My wife always randomly hits the up or down button, then gets upset if I explain why she should only pick the one she really wants. She forgets the next time. I think some people never really understand how elevators work. See also: the keep open / close doors button. I had one building administrator explain to me we should add a delay of 10 seconds to the "quickly shut door" button because otherwise she kept getting…

This reminds me of my partner, who always sets car air conditioning to 50F (the min) or heat to 90F (the max) because she thinks it makes it get cold or hot faster.

And of course a few minutes later we’re freezing or roasting. She sees the temps setting as controlling intensity of cold/hot rather than just, you know, the temperature you want.

Re: Show HN: Elevators

#355
One elevator feature I specifically noticed at Apple Park but haven't seen anywhere else: elevator prefetching to the ground floor.

I.e. in a bank of 2 elevators where one is resting on ground and the other is resting on a different floor, as soon as someone calls the ground elevator (which is already there and immediately opens) the other elevator (if idle) will move to the ground floor so that there's no delay the next time someone calls one from the ground floor.

Re: Show HN: Elevators

#356

One elevator feature I specifically noticed at Apple Park but haven't seen anywhere else: elevator prefetching to the ground floor. I.e. in a bank of 2 elevators where one is resting on ground and the other is resting on a different floor, as soon as someone calls the ground elevator (which is already there and immediately opens) the other elevator (if idle) will move to the ground floor so that there's no delay the…

Branch prediction or Floor prediction. If we know the traffic pattern from past data, we can optimize for it.

Re: Show HN: Elevators

#358

One elevator feature I specifically noticed at Apple Park but haven't seen anywhere else: elevator prefetching to the ground floor. I.e. in a bank of 2 elevators where one is resting on ground and the other is resting on a different floor, as soon as someone calls the ground elevator (which is already there and immediately opens) the other elevator (if idle) will move to the ground floor so that there's no delay the…

Branch prediction or Floor prediction. If we know the traffic pattern from past data, we can optimize for it.

Lazy evaluation would save on money. Branch prediction would save on wait times. In places electricity can shut down, lazy evaluation would be preferable to make it work longer on limited battery.

Re: Show HN: Elevators

#360

> Destination Dispatch [...] are in general worse I wonder if this is an artifact of how the author used random destinations. I worked in a building that used Destination Dispatch, and the common travel pattern seemed to be: - Everyone who is not on the ground floor generally want to go to the ground floor. - People who are on the ground floor generally travel in large groups to the same destination. This happens bec…

It is almost certainly because of the way the simulation was performed:

It turns out these fancy kiosks are in general worse for wait times compared to the traditional good ol' up and down buttons. There are certainly edge cases when the kiosks can win out (extremely tall buildings with 8+ cars per elevator bank) but for the majority of cases, simple up down buttons reign supreme.

This counterintuitive result is all thanks to the rebalancing step where every 5 seconds, the system re-optimizes each elevator's path. The kiosk enforces rigidity, you must get in the assigned elevator.

There should be no way that only having more information results in a worse outcome. At minimum, you could ignore the extra information, and achieve the same results as using up and down buttons.

Seems like the real reason it performed worse in this simulation is that when they implemented destination dispatch, they assigned an elevator at time of request, and had no system for reviewing and updated that assignment.

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