PM_ME_VINTAGE_30S [he/him]

Anarchist, autistic, engineer, and Certified Professional Life-Regretter. If you got a brick of text, don’t be alarmed; that’s normal.

No, I’m not interested in voting for your candidate.

  • 1 Post
  • 9 Comments
Joined 2 years ago
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Cake day: July 9th, 2023

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  • using more volts than the electric chair

    Well…voltage isn’t really the whole story. You really need the voltage and current to multiply to a power, then apply that power for enough time for it to be dangerous. For example, typical static shocks are between 4000-35000V, but they only transmit a few millijoules of energy. By way of comparison, these are similarly sized voltages to those used in primary distribution (i.e., not the lines passing by your house, but the ones feeding those lines), and those can kill you instantly because they carry a shitload of energy.

    And in a roundabout way, that’s how the electric chair actually works in the real world: it basically pumps energy into your body until you cook from the inside. There are definitely some deaths due to disruption of the heart. The aim of the machine was to demonstrate that AC is dangerous, and the main danger over DC is that AC causes muscle spasms, particularly your heart if electricity flows through it. However, most victims of them are basically cooked to death. The electric chair as it is currently implemented is not a fast or humane way to die. If you wanted to make it faster, you would need a much higher voltage and current pair, which would make the method (more) infeasible from a financial standpoint. (Obligatory: we should not be executing people at all.)

    Which is why fractal wood burning IS super dangerous! It requires you to work close to a live microwave (oven) transformer (or one of similar size) and the circuit it is connected to, which could very quickly pump enough energy into your body to disrupt it and kill you almost instantly.






  • I created this on my phone in MATLAB. You can probably do this in Octave with similar or the same code.

    Figure 2024-01-14 17_18_24~2

    First, I downloaded the image from Lemmy, then uploaded it into my MATLAB app. I renamed the image to image.jpg, then ran the following code:

    image=imread(“image.jpg”) imagesc(log10(abs( fftshift(fft2(image)) )))

    fft2 applies a 2D Fast Fourier transform to the image, which creates a complex (as in complex numbers) image. abs takes the magnitude of the complex image elementwise. log10 scales the result for display.

    Then I downloaded the image from the MATLAB app, went into the Photos app and (badly) cropped out the white border.

    Despite how dramatically different it looks, it actually contains the same [1] information as the original image. Said differently, you can actually go back to the original with the inverse functions, specifically by undoing the logarithm and applying the inverse FFT.

    [1] Almost. (1). There will be border problems potentially caused by me sloppily cropping some pixels out of the image. (2). It looks like MATLAB resized the image when rendering the figure. However, if I actually saved the matrix (raw image) rather than the figure, then it would be the correct size. (3) (Thank you to @[email protected] for pointing this out.) You need the phase information to reconstruct the original signal, which I (intentionally) threw out (to get a real image) when I took the absolute value but then completely forgot about it.