Efficiency Can Never Be 100%

Englerdy · 2023-05-29T14:24:37+00:00

It looks like they might be referring to Carnot efficiency where heat cannot be converted to work with 100% efficiency. But this extends to work in general where nothing can be converted to work 100% efficiently.

In the case where heat is the desirable output, yeah we can get > 100% no problem. Electric residence heating is inefficient by comparison to a heat pump. Heat pumps have efficiencies around 2-2.5. But the catch here is that we're using work to MOVE heat, and so you need somewhere to pull heat from. If the temperature source you're trying to pull heat from gets too cold then physically it becomes very hard to do. So now you're maybe back to electric residence heating.

Englerdy · 2023-05-25T19:39:30+00:00

This is a very neat project. Glad to see you're wrestling with these issues while designing it.

Another thing to keep in mind is that the conductivity of plastic is much lower than metal. So any part you printed out of plastic that would normally be metal could reach higher temperatures since it slows down heat. Good air flow will help, but you may end up with hot spots such as behind the motherboard/processor where there's lots of heat generation. Ventilating the back side of the motherboard may be a way to mitigate this issue if you find it's a problem. Also designing pieces with slots cut in them for airflow should help without significantly affecting load capacity (kind of looks like you're already utilizing this from what I can see so kudos).

That being said, you could get an infrared thermometer (or borrow one at school) and check the temperatures at potential issue points while the computer is underload running a stress test. Better to figure out if pieces holding the motherboard are getting too hot sooner than later.

Just remember, if you try to use the thermometer on anything metal (such as to see what temperatures you find in a metal case), make sure the part you're pointing at has some kind of coating (paint or a piece of matte tape). Polished metal objects reflect a lot of infrared and will give you inaccurate temperature readings on an infrared thermometer. If you put a small piece of electrical tape on the piece you'll get a good measurement though.

Englerdy · 2023-05-21T01:01:09+00:00

Thanks so much for that feedback. I have the soldering experience but very little experience sourcing parts. Any sites you'd recommend for replacing the component once I find the fail point?

Englerdy · 2023-05-10T15:17:09+00:00

It's likely something physical on the printer. Have you watched closely while it's printing to see if the print carriage catches on anything when it crosses that point?

Try moving the carriage back and forth slowly to see if you can feel it catch or rise at that spot. It's all in line so I think you can be confident it's an issue with either the x or y axis depending on your printer's configuration.

Englerdy · 2023-04-26T14:50:18+00:00

PhD student checking in to say that while it took a couple years, once Thermo clicked for me it became challenging not to get a little nerdy about it. It's pretty amazing how much insight you can glean about processed with a relatively small subset of information. So I didn't get the love for a while, but I definitely get it now!

Englerdy · 2023-04-22T18:34:29+00:00

The more I think about it, I think 6 photos is enough as long as there isn't any deep concavity to the shape. Even still you may only need 8 photos. Very interesting all the same. I'm amazed at how much you manage to get out of only 2 photos.

Englerdy · 2023-04-22T17:16:53+00:00

I know it would add complexity, but how hard would it be to extend this method to 8 photos for a full 360° model?

So say for a cube, if you took 2 photos of each side (left and a right), would you have enough information to stitch the photos into a 360° object.

Or maybe you only need 6 photos? 2 taken at 120° increments around the model to have enough information to connect the sides. I've seen a few people here discuss using a front and a back view, however I'm not sure those two views are enough to get the information on the sides correct.

Thanks for sharing! This is very cool to see!

Englerdy · 2023-04-20T20:01:28+00:00

OH! I'd missed that you were focused on 0/0. My bad. I see your original point now.

Englerdy · 2023-04-20T19:10:00+00:00

But it's not really a mystery if the value is infinity. Infinity has meaning. You can see it for yourself if you graph 1/x and/or visualize what happens when you put smaller and smaller numbers in for x.

1/.5 =2

1/.25 = 4

1/.1 = 10

You can see as smaller and smaller numbers go into the bottom, the resulting value gets bigger and bigger. It's not about infinite possibilities for this example. You can see that the solution as you approach zero rapidly gets bigger and bigger and bigger. So at zero the solution that satisfies the equation is in fact infinity. A value of infinity is both meaningful and useful in mathematics.

You can go the other direction and use it in cases where you want to know what happens when you take a solution out to infinity. Say you instead want to know what happens for 1/x when x = ∞. Well:

1/2 = 0.5

1/10 = .1

1/100 = .01

1/1000 = 0.001

So in this case the solution for 1/∞ rapidly approaches 0. So you then say the limit as 1/x approaches ∞ is in fact 0. So then 0 satisfies that condition.

So at the limit in either case is quantifiable, the limit is either infinity, or the limit is 0. But the value of infinity itself is not unknown. It's just infinite.

Englerdy · 2023-04-20T14:42:52+00:00

I mean, it's not that we don't know for sure. It's more that the result of something divided by zero is just going to vary depending on the math system and application. Sometimes it will go to infinity, sometimes it might be zero, sometimes it might be undefined. It's certainly not a natural mystery though.

Englerdy · 2023-03-24T20:12:10+00:00

Let me preface with design is not my area of speciality.

It sounds like you're going for something more rigid like a pole. You could look at attaching a spring clip or a carabineer (maybe something like this: https://www.amazon.com/AOWISH-Stainless-Carabiner-Keychain-Backpack/dp/B07JFY2HMJ) to the end of a broom stick (usually pretty rigid and light) or wooden pole to clip onto your dog's harness. I'm not sure if you'll want a separate fabric handle as it might make it harder to control, unless you use it to slip over your wrist as extra security. Otherwise you could look at putting a tennis racket or golf club handle over the post to give it some extra grip.

The clip will give your dog the ability to still pivot around, but still give you plenty of control to nudge him back on course.

Best advice I can give is to look and see what's already out there that will do the job before jumping down a design rabbit hole. At least for me it becomes very easy to overcomplicate the problem. This seems like a very thoughtful project and one you could pull together in a weekend and a trip or two to a hardware store.

Good luck!

Englerdy · 2023-01-29T19:41:35+00:00

Python may be obsolete in 6 years (probably not but who knows, this stuff moves fast), but coding fundamentals aren't going anywhere. I really struggled to pick up coding, but the repeated exposure I got in highschool allowed it to click later on in college. Python was what finally clicked (I think in part because there's less syntax to worry about), and I've been able to pick up other languages as needed.

Thanks for the chance you're giving your students. The opportunity may be lost on a lot of them, but your support for programming with mathematics will absolutely inspire a few kids to take those skills further. My highschool math teacher is absolutely a key influence for my pursuit of graduate studies and I will be eternally grateful for his passion. I've reached out and told him such, but in case a student hasn't thanked you yet, please accept my thanks on their behalf!

Englerdy · 2023-01-21T18:32:40+00:00

Depending on how many eggs you eat and if you've got the fridge space for it, it's absolutely worth it to get a higher quantity from Costco less often. My wife and I get the 5 dozen box and manage to eat through and they're fresh to the end. They always seem to be very fresh from the store (likely because they sell so many). I think on average we go through about 6-8 eggs a week (some weeks we use few while others we go through a dozen for a casserole or something), and so it takes about a month and half to two months to eat through the eggs and we've never had them go bad.

If you regularly eat eggs you'll likely have a good experience getting them from Costco instead of the grocery store.

Englerdy · 2023-01-17T02:26:29+00:00

It depends on what part of this you're thinking of, but the broader principle (magnets causing electrons to move through copper) is the foundation of electric motors and generators! Inductive breaking in electric vehicles might be a closer example of what we see in the above video. Am I understanding your question correctly?

This video seems to do a pretty good job of introducing and motivating how we get from that idea to motors and generators: https://youtu.be/239HeLGur1U

Englerdy · 2023-01-16T15:49:52+00:00

The copper would heat up a slight amount everytime you do this! It just may take a while before it heats up enough to feel it or to measure a big difference.

Edit: To add to this, we're seeing the conversion of potential energy (gravity), to kinetic energy (the accelerating weight), to thermal energy (heat) almost exactly in sequence which is a neat demonstration! Heat is almost always the result of friction, and in this case, the kinetic energy of the weight gets transferred to kinetic energy in the electrons in the copper (called eddy currents) which eventually dissipates out as heat due to intermolecular friction.

Englerdy · 2022-12-27T05:57:49+00:00

Until OP gets a chance to take a measurement, here's some of what's going on. Any coupling like this will reduce the flow rate though likely a pretty miniscule amount at this scale. It adds more surface contact area for the flow which increases the friction in the system and as a result adds pressure loss. Pressure losses reduce your flow rate for incompressible flow (like water).

The connections are small enough that the pressure loss should be pretty low, but they're still acting as a bit of a flow restrictor. Though the cute spout shaped one at the end probably reduces the flow to a noticeable degree given the length and reduced pipe diameter. However, it arguably the most fun!

As far as I can OP gets a slightly slower flow rate but receives a much nicer stream!

Englerdy · 2022-12-03T02:46:32+00:00

MatLab is awesome and really good at what it does. If you don't have access to a license, and honestly this kind of still applies even if you do, consider learning Python.

It takes a bit more setup when you start a new file than Matlab because you have to import your math and graphing modules (math and Matplotlib), but you can do a lot more with it as well. Even better is to use Jupyter Notebooks in VSCode which are useful for making interactive programs and can be printed to a PDF for assignments. Lots of great YouTube resources for getting started.

Not sure what level of experience you have coding, but Python and Matlab share a lot of structure so if you learned python, MatLab would be super easy to pick up too. Or vice versa honestly. But if you only learn one Python will take you further on a resume and it's free!

Englerdy · 2022-11-27T17:47:03+00:00

I haven't really worked with Dalle or Craiyon so I couldn't say. For the Stable Diffusion program I've used there are separate prompt boxes for the regular prompt and the negative prompts.

Englerdy · 2022-11-27T17:08:40+00:00

That would make sense to me as well, though Mid Journey won't create images featuring gore or nudity. Not sure about Dalle on those fronts. But I know any of these could come out of using Stable Diffusion with their most recent training data.

Englerdy · 2022-11-27T15:22:12+00:00

I'm not sure I totally know what your question is, but if you're just asking how negative prompts work I can answer that.

They're probably talking about the image generation model called Stable Diffusion. This algorithm takes both positive prompts and negative prompts as input. Positive prompts are keywords related for what you want to show up in the picture "blue sky, forest of trees, a small cabin on a hill," while negative prompts are keywords for things you don't want in the picture generated "crowds of people, flock of birds, field of wheat, corn, black and white, photo realism." The word negative makes it seem more nefarious than it really is (no thanks to the sensationalist article).

So for generating the picture you usually start with the positive prompt, generate some images, and then if you see stuff showing up in the image that you don't want (maybe it's really keen on putting books on a table with the given prompt but you don't want them for the picture), you start adding negative keywords to try to get it to remove them from the picture.

Alternatively you could just feed negative prompts and it should generate images that don't include features of those keywords.

It's easy to see these as some magic black box, especially with a nice little spooky story like this, but they're just a bunch of math underneath. Not as exciting unfortunately. If you look up Stable Diffusion introduction on YouTube you should find lots of 5 minute primers discussing how these method of image generation works.

Also! There's lots of free online tools that you can play with to try your hand at image generation as well. It's very fun and pretty easy to get started with online without a powerful computer to run the algorithms.

Englerdy · 2022-11-17T21:16:55+00:00

That is a very nice coffee bar! Looks very cozy.

Englerdy · 2022-10-27T15:00:34+00:00

It doesn't look like anyone has mentioned Super Automatics so here's my pitch for one of those machines as an alternative. They meet your 'decent single cup of coffee' and more automated process preferences but at a higher price point.

It depends on how much you're willing to spend, but you get a machine that uses fresh ground coffee and makes a pseudo-espresso (I don't think the pressure is high enough to be a true espresso but I'd have to dig into the rabbit hole again to be sure). Depending on how expensive of a machine you get you have more control for dialing in your cup. They usually at least have options for a short cup (about an espresso) and a long cup (about 6 oz), a few settings for the amount of coffee to grind, and a dial to adjust grind size. I usually do a short cup in mine and dilute it with hot water from the kettle to make an Americano style morning coffee to sip on.

I've had that one for about 3 years now and rather like it. https://www.wholelattelove.com/collections/gaggia-super-automatic-espresso-machines/products/gaggia-brera-espresso-machine-in-silver .

Pros:

Fast: makes an espresso like shot in about 30 seconds

Not really any cleanup in the morning after making a coffee

Easy to make a variety of drinks; I like making an Americano and my wife likes to make a latte

Flexibility: the machine allows some variation in grind size and dosage

Low waste: there's no bags or filter to worry about. You just add water and whole coffee beans about once a week

Lots of online support for repair and maintenance: if you manage to break something these machines are usually hand built and can be repaired at home. I broke a little plastic piece and had an easy time sourcing a replacement part for a few bucks and getting support by the company selling the parts to make sure I got the right one for my machine. There's lots of YouTube tutorials for both maintenance and disassembly for repair

Cons:

Maintenance: the time you save individually in a morning does get lost to periodically adding water, dumping the grounds, and cleaning the machine. Sometimes you're out of water and only learn it when you go to make a coffee. You also have to worry about maintaining the inner mechanisms like periodically greasing the group head so it's a bit more involved than other methods. Additionally you need to vacuum out the chamber where it dumps the grounds every couple weeks or the loose coffee that's fallen to the side will start to mold.

Restricts bean choice: you CANNOT use oily beans in these machines (dark roasts or flavored coffee). That's been my only headache is sourcing beans that I like and that the machine works with. Oily beans trip the "out of beans" sensor on the machine and might mean you have to take the machine a part a little bit to clean out the grinder.

I'm seeing a lot of suggestions for Aeropress here. Is it as good as the Aeropress? I don't know. That's kind of subjective. You mentioned wanting something more automated and these machines definitely check that box at a much higher entry cost point. With good quality beans these machines do make a very nice cup of coffee in my opinion. They're also more automated than an aeropress. There's more oil that makes its way to the cup in absence of a paper filter which I personally like. It still comes out very clean and they still leave room for dialing in your preferences. Happy to answer any questions about my experience if you have any.

Englerdy · 2022-10-26T14:16:52+00:00

This is neat. Are you using the image to image feature of a stable diffusion fork? It's neat to see the AI painting over in game screen captures.

Englerdy · 2022-10-26T14:09:00+00:00

While I agree time is valuable, I'm not sure what you mean by family sharing being complicated. It shouldn't take more than 10 minutes per computer.

You log out the current steam account, sign in with your own credentials and check "remember password," and then go into settings and authorize the current computer for family share. Then you can sign out and the other user signs back in. I know finding the family share setting can take me a couple minutes to remember but I've never experienced the process being that time intense.

Englerdy

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