xavieralexandre
Joined 15 years ago
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81
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50
Member since
Aug 4
Recent submissions
Comment · 7 months ago
Comment · 9 months ago
Thanks. I was mostly basing my answer on my experience with nautical charts, where declination corrections are typically uniform over relatively large areas and local anomalies are less of a concern. I hadn’t considered how much more variable the field can be in terrestrial use.
Comment · 9 months ago
You are linking to the magnetic anomaly grid, which is primarily intended for geophysical research and modeling local variations.
For a basic compass app, you can rely on the World Magnetic Model (WMM) instead: https://www.ncei.noaa.gov/products/world-magnetic-model
From that, you can pre-compute a low-resolution declination grid. NOAA even provides one here: https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml#i.... That’s only a few KB of data and requires just a simple declination subtraction based on lat/lon, similar to how it’s handled on nautical charts. This works fine as long as you stay away from the poles (and Alaska).
Comment · 2 years ago
Some types of glue absorb a lot of the laser energy. There are dedicated plywood optimized for laser cutting https://n-e-r-v-o-u-s.com/blog/?p=6042
Comment · 2 years ago
The article rightly points out the industrial impact of more powerful and compact lasers but I cannot wait for those PCSELs to reach the small workshop market. Having a cheap laser able to cut metal at home / small shops would be so useful (And sneakily dangerous as lasers are).
Comment · 2 years ago
Most plywood is glued with phenolic glues whereas melamine glues will behave better with a laser: https://n-e-r-v-o-u-s.com/blog/?p=6042
Comment · 3 years ago
He also did a nice post about a machine he built to test Blackberry pagers' radio reception: https://woodgears.ca/misc/rotating_machine.html
Comment · 3 years ago
You are not forbidden at the Federal level to have fixed units.
But many states do indeed requires a permit to install fixed units. And have strict regulations such as self producing half of the electricity required by the installation.
Here are a few examples of such regulations:
- Geneva (the most strict state): https://www.ge.ch/installations-techniques-rafraichissement/...
- Fribourg: https://bdlf.fr.ch/app/fr/texts_of_law/770.1/art/16
- Vaud: https://www.vd.ch/fileadmin/user_upload/themes/environnement...
One of the side effect of such regulation is that many business and houses will use cheap non-fixed units with open door and windows instead of installing proper reversible heat pumps.
Comment · 3 years ago
It looks like someone took the "Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway" sneakernet idea literally.
Comment · 3 years ago
I love reading those articles about new materials. Since reading James Edward Gordon's The New Science of Strong Materials: Or Why You Don't Fall through the Floor (https://press.princeton.edu/books/paperback/9780691180984/th...), I’ve been trying to keep in touch with the development of new materials. Still, I find it hard to understand which materials get into production. You tend to read news about new materials when a press release is published (as it is a relatively discrete event), but rarely about the fact that an industry has progressively adopted a new material that it regularly uses in production. It is even worse if there isn't a corporation or institution behind it to promote it.
For example, I read many articles about Flash Bainite Steel (https://www.osti.gov/servlets/purl/1461193) in 2015, and I’d love to know if the industry has adopted this process. (I am especially curious about its potential use as tubing material for bicycle frame building).
Comment · 4 years ago
Also the planet could well become greener with global warming but the issue is the rate of change. Even if the new growing conditions were great for some crops, evolving our entire agriculture and food regimen to them in a few decades is a huge ordeal.
Comment · 5 years ago
Steam bending was and is still used for mass-produced furniture: https://en.wikipedia.org/wiki/No._14_chair
And there are also very interesting modern takes on bending wood such as compwood: http://compwood.com/processen/
The wood is heated and compressed longitudinally. Once cold it stays (super) bendable as long as it is still wet.
https://blog.lostartpress.com/2020/07/22/a-little-bit-about-...
Not anymore. That is exactly the purpose of Darpa Ambient program: https://www.darpa.mil/research/programs/atomic-magnetometer-...
Demo from 2022: https://www.youtube.com/watch?v=VTnIXWCBYTw