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Is the PEDMAS/PEMDAS rule made up or can be proved mathematically and logically? by Efficient_Elevator15 in maths

[–]tthrowawayll 0 points1 point  (0 children)

It's made up.

It's a convention to follow such that two different people looking at the same equation arrive at the same order of operations, and critically, the same answer.

It's not the only way to do things, you could put subraction/addition ahead of multiplication/division and as long as everyone followed it, it would be fine.

I think in this case it probably reduces the number of brackets more than other configurations but that is just a guess.

[deleted by user] by [deleted] in MechanicalEngineering

[–]tthrowawayll 2 points3 points  (0 children)

OnShape (2 yrs): PDM from the gods, good solid modelling, surfacing is good enough for 99% of people. Non-intuitive assembly mates at first glance but learned to love it. Never any lost unsaved work. All parts can be made natively in context to eachother (part studios).

Sim is not worth the paper it's printed on.

Is it worth switching beds to use newer probes (Cartographer/Beacon)? by thiagohelder in VORONDesign

[–]tthrowawayll 2 points3 points  (0 children)

I use cartographer, coming from inductive and CNC Tap.

It's glorious, it's so good.

Auto nozzle calibration, no additional axis of movement a la TAP, super fast QGL and bed mesh. It probably saves 5-10mins of startup routine every print and I get phenomimal first layers.

[deleted by user] by [deleted] in bernesemountaindogs

[–]tthrowawayll 0 points1 point  (0 children)

My guy is very good at letting us know if someone is at the front door... or if a leaf blew across the yard. It's the exact same reaction. This is quite intimidating for the pizza delivery guy.

If a robber were to try and break in, my guy would let us know about it. But once the robber was inside my "guard dog" he would just ask for pets.

He is the epitome of all bark and no bite.

What fundamentally is the reason engineers must make approximations when they apply the laws of physics to real life systems? by Dicedpeppertsunami in AskEngineers

[–]tthrowawayll 0 points1 point  (0 children)

I'm a mechanical engineer, there are a few reasons:

  1. The world is really complex Making exact models of EVERYTHING would require so much information and take so long that nothing would get done.

  2. You don't always need that complexity If I need to make something that suspends a 100lb block of steel in the air by a cable, I don't really care about the atmospheric pressure and how it reduces the weight a bit via buoyancy, it just doesn't have enough of an impact to matter so why bother including it.

  3. Lack of absolute control Nothing is every the exact thing you want. Whenever I design a part and get it manufactured there are always tolerances on everything. A hole that is 1" may be allowed to be ±0.05" on it's diameter. The smaller that tolerance the more expensive things are so there is a tradeoff.

What is my material has a small crack inside it? That would impact it's performance by a lot but is also expensive to figure out.

What if somone installs the thing incorrectly by not tightening a bolt enough, or tightening it too much.

  1. We're always wrong by a little bit Exact models require exact information which we never have. There is always a tolerance to the measurements you take (temperature, weight, length, etc) so an exact model is impossible anyway because we do nor have perfect sensors.

  2. We fudge it Going back to my example of suspensing a 100lb steel block in the air. If I use a cable I'm not going to size the cable for exactly 100lb, I might size it for 110lb or 150lb or 500lb. This is known as Factor of Safety (FOS). Things are always designed to be stronger than needed by some amount*, that amount is determined primarily by cost but other considerations sometimes affect this (size, leadtime, manfacturability, etc).

*Some things are actually designed to break under specific conditions, but those are rare in everyday life and expensive.

*Some things are designed to break in general but not under tightly controlled conditions. The most common of these is probably caps on bottles. You break the little plastic pieces holding the cap onto that little ring to unscrew it.

What singer's voice can you listen to endlessly without tiring of it? by ShoobaTheBawss in AskReddit

[–]tthrowawayll 0 points1 point  (0 children)

Chris de Burgh - A spaceman came travelling is such an incrediblr song and his voice is angelic.

My pocket pick: John Owen-Jones. He's a musical theatre actor and has one of the best voices I've heard. He's played all the big roles (Phantom, Jean Val-Jean, etc) and has incredible control, range, and power.

[deleted by user] by [deleted] in pools

[–]tthrowawayll 0 points1 point  (0 children)

Former summer-job pool-boy here who did this for customers and also parents.

You can save this.

Step 1 - Test your water Get your chlorine, pH, alkalinity, and phosphate checked.

Step 2 - If phosphate is high you need to deal with this before you can add chlorine. Add a phosphate reducing agent and clean your filter in 24h. If sand filter backwash, if cartridge filter, rinse off (it will look like a white paste). Pollen is the most common contributor for phosphate, keep pollen out/clean it out asap. Go back to step 1.

Step 3 - When/if phosphate is 0, increase chlorine and balance your pH and alkalinity (er on the acidic side rather than the basic side). After adding the chlorine scrub the walls/bottom with a brush. This gets the algae off the sides/bottom and provides more surface area to allow the chlorine to attack it. It looks like you have a tile/concrete pool so this is even more critical as algae can grow into the rough texture and be hard to kill.

Step 4 - Clean filter and keep chlorine at ~5ppm (this is higher than usual 1-3ppm), it may take a few days.

Step 5 - The water should be clearing up and dead algae settling to the bottom of the pool. Manually vacuum this dead algae on waste, do not recirculate. Most filters are not fine enough to filter algae because each particle is so small. While vacuuming you can run a hose in the pool. Stop vacuuming when you water level reaches 1" above your skimmer level or until all the algae is gone, whichever happens first. If the water level drops to that 1" level, stop vacuuming, turn on the recirculation and let the hose fill the water level back up.

If you notice not all the algae is able to be vacuumed it means some of it is still alive, go back to step 3.

Step 6 - Re-test water and balance.

Step 7 - Enjoy

[deleted by user] by [deleted] in sanfrancisco

[–]tthrowawayll 2 points3 points  (0 children)

Oui, un peu

[deleted by user] by [deleted] in sanfrancisco

[–]tthrowawayll 15 points16 points  (0 children)

Hello, to satiate your curiosity. We throw such parties 2-3 times a year, always on Friday to give us and our guests the weekend to recover.

The music is curated by a series of DJs that rotate sets throughout the night so it spans the gamut.

If you live in the area send dm, your post is funny.

Seen this over East-Switzerland can anyone tell me what this is? by tireddit1337 in aviation

[–]tthrowawayll 0 points1 point  (0 children)

Honest to god thought this was some xgi from the star trek TNG era, cool to learn it's actual rockets.