critical frequency


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critical frequency

[′krid·ə·kəl ′frē·kwən·sē]
(electronics)
(electromagnetism)
The limiting frequency below which a radio wave will be reflected by an ionospheric layer at vertical incidence at a given time.
(geophysics)
The minimum frequency of a vertically directed radio wave which will penetrate a particular layer in the ionosphere; for example, all vertical radio waves with frequencies greater than the E-layer critical frequency will pass through the E layer. Also known as penetration frequency.
References in periodicals archive ?
The design of three horizontal slots on the brake pad backplate makes the critical frequency change 770 Hz, which leads to the decoupling of the brake pads and the brake disc.
The critical frequency is 145.42Hz and the approximation value based on Equation 18 is 145.28Hz, so these two values are much closed to each other and the error is within 0.1%.
Then, the critical frequency [[omega].sub.ci] of the band-pass filter in (32) is automatically tuned to be the identified dominant vibration mode.
At higher frequencies, the breakout transmission loss will be governed by the mass per unit area of the duct walls and the critical frequency. Because these gage and reinforcement effects were not investigated, there are no plans for updating the ASHRAE Handbook information.
4 was applied to the PP and PO data to determine a critical frequency as a function of stress amplitude.
In this particular study, the sampling distribution of critical frequency and electron concentration are presented in histogram plots shown in Fig.
The IONORT-ISP results were compared to a more elaborate semiempirical formula, that is, the ICEPAC [23], which refers to various phenomenological parameters such as the critical frequency of E-layer.
Determination of the critical frequency protocol firing balls of table tennis at specific protocol.
These findings were reinforced in a recent study by Zagatto and Gobatto (2012) where no significant correlation was found between W' from a critical frequency test with the maximal accumulated oxygen deficit (MAOD), which is considered the gold standard test when assessing anaerobic capacity.
The first two cases lead to finite and nonzero values of the critical frequency, whereas the third and fourth cases lead to critical frequencies [[omega].sub.c] = 0 and [[omega].sub.c] [flecha diestra] [infinito], respectively.
The beam specimen is excited around critical frequency using shaker and corresponding output response from accelerometer and PZT patches are collected.
Also, it is noted that the peak is at a critical frequency (5000-9000 rpm), and then it begins to settle out at maximum speed close to critical frequency.

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