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  2. Schumann resonances - Wikipedia

    en.wikipedia.org/wiki/Schumann_resonances

    The global electromagnetic resonance phenomenon is named after physicist Winfried Otto Schumann who predicted it mathematically in 1952. Schumann resonances are the principal background in the part of the electromagnetic spectrum [2] from 3 Hz through 60 Hz [3] and appear as distinct peaks at extremely low frequencies around 7.83 Hz (fundamental), 14.3, 20.8, 27.3, and 33.8 Hz.

  3. Extremely low frequency - Wikipedia

    en.wikipedia.org/wiki/Extremely_low_frequency

    The fundamental Schumann resonance is at approximately 7.83 Hz, the frequency at which the wavelength equals the circumference of the Earth, and higher harmonics occur at 14.1, 20.3, 26.4, and 32.4 Hz, etc. Lightning strikes excite these resonances, causing the Earth–ionosphere cavity to "ring" like a bell, resulting in a peak in the noise ...

  4. Winfried Otto Schumann - Wikipedia

    en.wikipedia.org/wiki/Winfried_Otto_Schumann

    Winfried Otto Schumann (May 20, 1888 – September 22, 1974) was a German physicist and electrical engineer who predicted the Schumann resonances, a series of low-frequency resonances caused by lightning discharges in the atmosphere.

  5. List of temperature sensors - Wikipedia

    en.wikipedia.org/wiki/List_of_temperature_sensors

    The integrated circuit sensor may come in a variety of interfaces — analogue or digital; for digital, these could be Serial Peripheral Interface, SMBus/I 2 C or 1-Wire.. In OpenBSD, many of the I 2 C temperature sensors from the below list have been supported and are accessible through the generalised hardware sensors framework [3] since OpenBSD 3.9 (2006), [4] [5]: §6.1 which has also ...

  6. Resonator - Wikipedia

    en.wikipedia.org/wiki/Resonator

    For example, a multiple degree of freedom system can be created by imposing a base excitation on a cantilever beam. In this case the standing wave is imposed on the beam. [ 5 ] This type of system can be used as a sensor to track changes in frequency or phase of the resonance of the fiber.

  7. Resonant ultrasound spectroscopy - Wikipedia

    en.wikipedia.org/wiki/Resonant_ultrasound...

    The inverse problem of deducing the elastic constants from a measured spectrum of mechanical resonances has no analytical solution, so it needs to be solved by computational methods. For the indirect method, a starting resonant frequency spectrum, f n c a l {\displaystyle f_{n}^{cal}} (n=1,2,...) is calculated using estimated values for the ...

  8. Electromagnetic acoustic transducer - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_acoustic...

    Easier for sensor deployment. Using piezoelectric transducer, the wave propagation angle in the test part is affected by Snell's law. As a result, a small variation in sensor deployment may cause a significant change in the refracted angle. Easier to generate SH-type waves.

  9. Normal mode - Wikipedia

    en.wikipedia.org/wiki/Normal_mode

    For example, a vibrating rope in 2D space is defined by a single-frequency (1D axial displacement), but a vibrating rope in 3D space is defined by two frequencies (2D axial displacement). For a given amplitude on the modal variable, each mode will store a specific amount of energy because of the sinusoidal excitation.