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Show HN: Elevators

john.fun

411–420 of 426 posts

Re: Show HN: Elevators

#411
post #370

Earlier quoted context omitted.

There’s also a strategy to jump the line. Say there’s a talk that just took place on the top floor roof deck of a small ~20 floor building. People who don’t want to wait in line with a hundred people, can take the stairs down one level, call the elevator on the way up to enter the car before it is filled, ride it up one level*, and then ride it all the way down to the ground floor. To prevent a riot, the building sho…

Also works for Buses and Trains. Go one stop the opposite way, then go back. This may take a couple minutes longer, but you'll have a seat for the rest of the journey.

Good tip. Somehow this feels more fair than the elevator example but I can't put my finger on why.

Re: Show HN: Elevators

#412
post #314

In my residential building we have two elevators, a big one and a small one, the small one can fit 3-4 people if they squeeze together, it can't fit a bicycle. And of course, they don't work independently, so if the small one is already on your floor the big one won't stop there, so if I have my bicycle with me, I need to send the small one to a higher floor first, and since people are using the lifts constantly, som…

Put the bicycle on its back-wheel, vertical?

Re: Show HN: Elevators

#413

> 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…

Destination Dispatch should also allow you to better optimize total travel time rather than just wait time. Especially in the tall office building case you could have an elevator that skips straight to the top floor instead of having to stop for people to get off people all the time.

Re: Show HN: Elevators

#414
I’d like to know about algorithms that determine where elevators “rest” during downtime. In the morning maybe all rest on the ground floor. Then perhaps during midday lunch rush, some elevators rest at an average floor of where most people got off in the morning. In the evening when people go home, maybe most elevators rest higher up where most people are.

Re: Show HN: Elevators

#415

Earlier quoted context omitted.

> I would not want to be in that building if an evacuation alarm sounded. why short term/long term stay would matter here?

Because short term stays put more load on the building systems, like the lifts, than perhaps the building was designed for. Regular tenants don’t come and go at anywhere near the rate short stay guests do.

why it would matter during evacuation when everyone leaves?

(tourists would be more likely to be outside anyway, so actually it sounds like better case)

Re: Show HN: Elevators

#417

Earlier quoted context omitted.

> 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. I don't think it's possible to have destination dispatch AND update assignment together, in the real world. - If the user clicks floor 26 and you tell them to wait at elevator G, you can't reall…

Interesting. I didn't realize that destination dispatch told the user what elevator to take at the time of request. (I've never used it.) Why not have active display above each elevator that says what floors it is going to when it opens?

Because it doesn’t know that until after it has completed the trip?

Re: Show HN: Elevators

#418
post #25

Earlier quoted context omitted.

And then when the elevator door opens, they ask the people inside: "Are you going up or down?" There's an arrow showing that, for Christ's sake.

"Questions are never indiscreet. Answers sometimes are."

When did you stop beating your wife?

Re: Show HN: Elevators

#419

This is commonly referred to as the "dial-a-ride" problem, which is an optimization problem with a multi-variate cost. Back in college for my senior design project we built a multi-axis closed loop servo system which would emulate a slide guitar. The dial-a-ride problem is identical to optimizing travel for a string of notes/chords.

Except it doesn’t really work if you play the notes in a different order.

Re: Show HN: Elevators

#420

One of the most frustrating assignments[1] (2011) in my computer science education was trying to build a better mousetrap for elevator control. [1]: https://clarkmoody.com/Moody_AgentBasedElevatorControl.pdf

Disk drive read/write algorithms have a lot in common with elevator algorithms. At least they did in the days of physical heads moving across a platter.

Those days aren’t gone - they’ve just moved to enterprise systems.
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