florinandrei

florinandrei t1_jd6bwq6 wrote

It definitely does have a kinetic energy.

The only thing is - when you go from kinetic energy to temperature, you run into all sorts of trouble if you do it for single entities.

Temperature is an inherently collective measure. If it's single particles, stick to kinetic energy.

What is the "temperature" of this marble I'm throwing? ;) (not the temperature of the glass, but the "temperature" of the marble as a single particle with some kinetic energy)

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florinandrei t1_jd6br1i wrote

> they exhibit different physical properties including changes in electrical conductance

Of course they do. I'm just saying - the borders between them are far more fuzzy than most people imagine.

E.g. consider the changes that occur in tar or pitch when cooled from the boiling point of water to the boiling point of nitrogen. It's liquid at one end. It's solid at the other. The changes are smooth, without any sharp transitions.

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florinandrei t1_jd4ubra wrote

Technically, you can associate a temperature to the velocity of the atom measured relative to the container, and therefore obtain a "temperature" for that atom. But a lot of concepts become quite strained when you reduce things to single atoms, and temperature is one of them. A single atom does not have a temperature in the normal sense.

To your initial question: the phases of matter are only defined for molecular or atomic collectives. Single molecules or atoms do not have a clearly defined phase of aggregation. Even for large molecular collectives it is not always clear whether they are solid, liquid, or gas. For example, on geologic time scales, even some "solids" can flow.

The phases of matter are more like convenience concepts. We use them to simplify discussions that would otherwise be complex. There's nothing fundamental about them. Do not get stuck in rigid categorizations there, because there's no point in doing that.

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florinandrei OP t1_jb7pefb wrote

> Isn't this what the ignore_index is doing?

No, it is not.

Let me repeat: ignore_index cuts holes in both the ground truth label frames, and in the prediction frames coming out of the model. Any pixels in those holes are ignored.

This includes pixels in the predictions from the model. You are ignoring chunks of the model's output.

> How else should we exclude them from the average metric?

By not computing metrics for that pixel value.

average_metric = sum(metric_index1 + metric_index2 + ... + metric_indexN) / N

Simply do not include it in the sum, and then just divide by N-1 instead.

What you are doing is not equivalent to that. What you are doing is: you discard pixels from both label frame and prediction frame based on the shape of some regions in the label frame alone. That makes no sense. Whatever the model's predictions happen to be in those holes, they are ignored even if they have pixel values different from ignore_index.

You are ignoring all the model's predictions in those holes, regardless of their pixel values.

You are discarding pixels from the model's output even if they have values different from ignore_index.

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florinandrei OP t1_jb7cujz wrote

The problem is: the current algorithm cuts holes in the prediction frames, based on ignore_index in the label frames.

Any pixels in the label frames equal to ignore_index will cause pixels in both label frames and prediction frames to be completely ignored from calculations. If some predicted mask pixels fall into those areas, they will be excluded from all calculations. This is the issue that needs to be addressed.

You cannot exclude pixels from the predicted frames based on pixel values in the label frames.

If there is some index you want to ignore altogether, because you are not sure about the quality of the labels, it is best to just exclude it from the calculation of the average metric.

If some users set ignore_index to the value of the background pixels, that will cut very large holes in everything, therefore discarding a lot of pixels from performance evaluation, and will severely skew the results.

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florinandrei t1_j2ff0l2 wrote

Reply to comment by HedgehogRoutine2695 in Ohm My Lord by ZevireTees

It only works when the signal is very strong, and it's an AM thing.

I've done this as a kid. There was a powerful AM station nearby, enough signal for listening in headphones. Using a huge wire antenna, good ground connection, and an output transformer, I was actually able to feed just barely enough signal in a small speaker. Placing the speaker in a small transistor radio box (like a DIY speaker box) made it audible in my room at a soft, but decent level.

There were no batteries in the schematic. All the energy came from the radio station. Since only one strong station was in the area, I didn't even need an LC frequency filter - a germanium diode was the only real component besides the headphones (or speaker + transformer). One side of a germanium transistor also works instead of a diode. Silicon diodes / transistors don't work.

The signal was plenty for comfortable listening in headphones. I was able to even use metallic rain gutters as an antenna, and my hand as a "ground connection" and it still worked okay. I could impress my friends by touching one wire to the rain gutters, and AM radio would play in the headphones.

High impedance headphones worked better. For the speaker, the transformer basically was just an impedance adapter - speakers have low impedance, but the schematic required high impedance for best results.

Here's the schematic for headphones:

https://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Simplest_crystal_radio_circuit.svg/515px-Simplest_crystal_radio_circuit.svg.png

Replace the headphones with transformer + speaker if you wish, but don't expect a lot of volume even in the best case.

If there is no strong AM station nearby, then it will not work at all.

General info and more complex schematics:

https://en.wikipedia.org/wiki/Crystal_radio

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