Musical instrument acoustics

Interesting: I went to look up exactly what a sound post does, and it’s not so much transmitting vibrations between the top and bottom plates as it is providing a fulcrum so that the bridge can transmit the sideways vibrations of the strings (constrained by the bow pressing on them) to vertical vibrations in the body. Plucked instruments like guitars don’t need that because the strings can vibrate in all directions

Music StackExchange: What’s the purpose of a sound post?

Diagram of the bridge, sound post and body of a violin, showing how the side-to-side motion at the top of the bridge (where the strings pass over it) are transmitted to vertical movements on the body of the violin via rotating around the point where the sound post and one of the bridge supports meet on opposite sides of the top plate of the violin body.    Image via the stack exchange answer linked here.

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Unusual photos of Martian landscapes from Mars Reconnaissance Orbiter

Nice small collection of unusual photos of Martian landscapes from Mars Reconnaissance Orbiter at Daily Overview. I don’t know what the blue triangle thing is.

The description doesn’t say, but I’m guessing most of them are false-color or exaggerated.

(Images originally from NASA)

https://www.getrevue.co/profile/dailyoverview/issues/mars-reconnaissance-orbiter-433906

#mars #space #photo

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Yesterday’s California power demand vs. forecast graph & how effective the 3pm Flex Alert was

Fascinating to look at yesterday’s California power demand vs. forecast graph & how effective the 3pm Flex Alert was at getting people to reduce power usage during peak hours. (That forecast demand peak was very close to the forecast supply peak.)

https://www.caiso.com/TodaysOutlook/Pages/default.aspx

Graph showing hour-by-hour power demand for August 17, forecast tracking a sine wave dipping to around 26K MW at 4am & peaking at 49K at 6pm. Actual usage tracks until 3pm, when it flattens, then stays below the forecast curve for the rest of the evening.

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An amazing composite photo of the Milky Way and Jupiter over the snow-covered Himalayas, via @apod. Photographer Tomas Havel took 8 exposures from the same spot over 3 hours and combined them to make this image.

An amazing composite photo of the Milky Way and Jupiter over the snow-covered Himalayas, via @apod. Photographer Tomas Havel took 8 exposures from the same spot over 3 hours and combined them to make this image.

APoD: The Milky Way over Snow-Capped Himalayas

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