randy
@randy@lemmy.ca
- Comment on This feels wrong. I love it. 3 weeks ago:
I’ve noticed that, if an equation calls for a number squared, they usually really mean a number multiplied by its complex conjugate.
- Comment on Research shows more than 80% of AI projects fail, wasting billions of dollars in capital and resources: Report 2 months ago:
It sure feels like we’re at the peak of the Gartner hype cycle. If so, the bubble will pop, and we’ll end up with AI used where it actually works, not shoved into everything. In the long run, that pop could be a small blip in overall development, like the dot-com bust was to the growth of the internet, but it’s difficult to predict that while still in the middle of the hype cycle.
- Comment on No one’s ready for this: Our basic assumptions about photos capturing reality are about to go up in smoke. 2 months ago:
Relevant XKCD. Humans have always been able to lie. Having a single form of irrefutable proof is the historical exception, not the rule.
- Comment on What are some common misconceptions about programming that you'd like to debunk? 9 months ago:
And here I was thinking of xkcd.com/664/
- Comment on [deleted] 10 months ago:
Also worth noting this article is nearly five years old. Rust’s first stable release was nearly nine years ago, so its (stable) age has more than doubled since then. I expect Rust would look a lot more mature if the article was written today.
- Comment on Protecting HDDs from (external) train vibrations 10 months ago:
Thanks for the update and graphs. That is an amazing improvement. In the “after” plot, it looks like any acceleration from the train is well below the noise level of your accelerometer. So, within the limits of your measuring equipment, you’ve effectively eliminated all train vibration. If I were in your place, I would declare success and move on with life! Don’t even bother with foam and rubber feet, because this configuration is working great.
But you could analyze further if you really want; there could be some train signal hiding in all that noise. Since there’s periodic noise in the Z axis, you could take a reading during a still time (computer off, no trains) and see where your spikes are in the frequency domain. Then you could apply a filter (or filters) to cut out that periodic noise.
But unless you’re really into learning about signal analysis, I’d say you could skip it.
- Comment on Protecting HDDs from (external) train vibrations 10 months ago:
None of the included experiments look to be exactly what you need. For characterizing your isolator, the included Acceleration Spectrum is close, though it records continuously, making it difficult to use to record impact response. For evaluating actual train vibrations, the user-defined Integrated Acceleration might be a start, but it doesn’t include the filtering needed to get good information. You could define your own experiments, but that’s probably even harder than analyzing the CSV data on your computer. At least on your computer you can change your analysis freely and immediately see results, rather than re-running the experiment every time.
- Comment on Protecting HDDs from (external) train vibrations 10 months ago:
Wow, I hadn’t heard of phyphox before (hadn’t even noticed @khorak@lemmy.dbzer0.com mentioned it in the OP). That’s very cool and I’ve installed it now.
- Comment on Protecting HDDs from (external) train vibrations 10 months ago:
I work in railway noise and vibration mitigation, and @scrion@lemmy.world has given you a great starting point. When we build rails and want to mitigate ground-borne noise and vibration (typically up to ~200 Hz), we generally mount the rails on soft pads and add extra mass to isolate the rails from the surroundings. The exact same approach will work at your computer. We don’t typically use tuned mass dampers for ground-borne vibration, so I think that will be overkill for you, but you can try if you like.
I wanted to suggest that, in addition to the feet/foam/plywood, you can also add a big chunk of something heavy to help with isolation. Like put a heavy rock on top of the foam, and your computer on the rock. The trick is this: if k is the stiffness of your foam, and m is the mass of everything on top of the foam, then your isolating frequency is at √(2k/m). All frequencies above the isolating frequency will by mitigated (the further above, the more they’re mitigated), while all frequencies below will be amplified.
(Quick aside if you actually want to calculate frequency with √(2k/m): check that your units for k and m are compatible, you should end up with a result in units of 1/s, which is actually radians per second, then multiply by 2π radians per cycle to convert to Hertz).
When it comes to measuring results, since your problem is in low frequencies, you can probably use your phone’s accelerometer assuming it reads fast enough (the sample rate must be at least double the highest frequency you care about). Mount it as rigidly as you can to your computer, since if the connection is soft, the phone will be in its own isolating system. The quickest way to test your isolator would be to hit close to the base with a hammer; impacts excite a wide range of frequencies equally, so in the frequency domain you should see vibration amplitudes following a shape something like these.
But as @scrion@lemmy.world notes below, you don’t really care about your isolator’s response, you care about what trains are doing to your computer. However, he said one thing I disagree with: it’s not the amplitude of the acceleration that you care about, it’s the amplitude of energy, and therefore velocity. This article gives a good introduction to ways you could analyze that. But now we’re getting way in to the weeds on what should be a simple project!
One last aside: if the vibrations in your building are bad enough, you could raise it as an issue with the metro operator. The US Federal Transit Administration sets standards that are commonly followed even outside of the US (see Table 8-1 in their Noise and Vibration Manual); if your measurements show vibration exceeding those limits then they might pay me to fix it :D.
- Comment on xkcd #2867: DateTime 11 months ago:
I really wish that list would include some explanations about why each line is a falsehood, and what’s actually true. Particularly the line:
The software will never run on a space ship that is orbiting a black hole.
If the author has proof that some software will run on a space ship that is orbiting a black hole, I’d be really interested in seeing it.
- Comment on Stealthy Linux rootkit found in the wild after going undetected for 2 years 11 months ago:
From the article:
The researchers have so far been unable to determine precisely how Krasue gets installed.
So no one knows yet. But I feel that the existence of malware in the wild is newsworthy, even if we don’t know how it got there. Regardless, you and I probably don’t have to worry about it unless you’re a Thai telecom.
- Comment on Canada's Carbon Price Working, So Of Course It's Being Attacked 1 year ago:
You must be thinking of a different grant, or you’re in a province where the carbon price is not federally run. The federal Climate Action Incentive payment is disbursed to everyone.
- Comment on Guinan has seen it before 1 year ago:
If there’s somethin’ strange
Sleepin’ in your bed
You might be Dr. Crusher. - Comment on A new smartphone again? Rethink unhealthy culture of frequent upgrades 1 year ago: