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9 votes
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What device is this, and how does it work?

Something like this? http://www.browninnovations.com/sound-dome/single-localizer-sound-dome As others have said, it is a speaker with a parabolic reflector to direct the sound down at the listener. ...
Andrew's user avatar
  • 766
8 votes

What device is this, and how does it work?

With a description as vague as that, it was probably a parabolic reflector with a speaker at its focus. Pointed straight down, the "beam" of acoustic energy would be reflected from the floor right ...
Dave Tweed's user avatar
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3 votes
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Defining camera as a passive radar

Not really. Firstly the RA in RADAR stands for RAdio which covers significantly longer wavelengths than the visible light (an in some cases near infra-red) which cameras can detect. While light ...
Chris Johns's user avatar
  • 15.2k
3 votes

Vertical wave action on bridge

I understand this question is about an event in Brazil and not the US. However, section 3.7.4 (Wave Loads) of the 2012 AASHTO LRFD Bridge Design Specifications simply says: Wave action on bridge ...
Rick's user avatar
  • 1,166
3 votes
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What is the difference between the wave equation and the advection equation?

As alephzero mentioned the difference is huge. I will explain mathematically and then physically. Mathematically, For any given partial differential equation of the form, $$A \frac {\partial^2\...
mustang's user avatar
  • 511
2 votes
Accepted

How can I calculate the total signal level (noise) of PC fans?

This is a pretty straightforward calculator: https://www.engineeringtoolbox.com/adding-decibel-d_63.html Basically noise level is dictated by your 2 loudest sources, so 50 dB + 40 dB (assuming they ...
jko's user avatar
  • 2,347
2 votes
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Generating 10 GHz Frequencies with Reasonable Power Requirements

UPDATE From clarifying the specs in comments: the poster wants a region with a high electric field generated by as low an input power as possible. You want standing waves, not propagating waves; ...
Alex I's user avatar
  • 175
1 vote
Accepted

Can ocean flows after a crashing wave be accumulated in one point to increase the water height of that location?

Yes water will go higher than the average height of the wave. Imagine an infintisimally small droplet hit the wall with an angle $\theta$. it reflects with an angle $2\theta$ with respect to the main ...
kamran's user avatar
  • 22.6k
1 vote
Accepted

What causes wavelength technologies to have longer range than other despite having the same frequency?

Three factors: Transmitter power: LoRa, for example, typically uses about 160x the power of Z-Wave. However, this alone cannot explain a 150x increase in operating range given that signal strength ...
Emily Conn's user avatar
1 vote

How to calculate the force of a cantilever beam at a given point of deflection?

This is not really an answer but a hint. I agree with you that the impact is not limited to the small collision zone and propagates back and forth throughout the length of the beam and the vibration ...
kamran's user avatar
  • 22.6k
1 vote

Is it possible for a microphone/sensor to detect soundwaves before it physically reaches the sensor?

The speed of sound is not a constant. The speed depends on the material the sound is traveling though. The speed of sound in aluminum, for instance, is roughly 20 times faster than air. If the ...
Eric S's user avatar
  • 915
1 vote

High frequency ultrasound effects on viruses and bacteria

Since this question is addressed around COVID-19, which is trending these days this response is focused on COVID-19 and using electronics to destroy the virus. The response is focused around ...
Mahendra Gunawardena's user avatar
1 vote

How can I calculate the total signal level (noise) of PC fans?

The standard rule of thumb for adding decibels is that doubling the sound power increases the dB reading by +3dB. Using an on-lone calculator for adding dB's, we find that adding two sound sources ...
niels nielsen's user avatar
1 vote

What emits more radiation, cell network or wifi?

So, after a little googling around. Cellphones typically transmit on 3/4 G at between 0.3 and 3 W - subject to tower location & interference. The out put power is managed by the cell tower. ...
pHred's user avatar
  • 176
1 vote

What can be the reason of the constant 50 Hz sound in my home?

Indeed, if the spectral content of the noise is peaked at the mains frequency, it is evidence of a motor somewhere in the building that runs all the time. This could be a ventilator or exhaust fan for ...
niels nielsen's user avatar
1 vote

Why channel 1, 6 and 11 are best for Wifi communication 802.11n?

All channels good but: National standards can control some parameters (gain, numbers of channels, gain in channel ...). Gain of Channel 1 can be less in some cases. I have 19 visible ssids in my ...
dash1121's user avatar

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