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The maximum thermal efficiency of a Diesel cycle is dependent on the compression ratio and the cut-off ratio. It has the following formula under cold air standard analysis: η t h = 1 − 1 r γ − 1 ( α γ − 1 γ ( α − 1 ) ) {\displaystyle \eta _{th}=1-{\frac {1}{r^{\gamma -1}}}\left({\frac {\alpha ^{\gamma }-1}{\gamma (\alpha -1)}}\right)}
The cutoff frequency is found with the characteristic equation of the Helmholtz equation for electromagnetic waves, which is derived from the electromagnetic wave equation by setting the longitudinal wave number equal to zero and solving for the frequency. Thus, any exciting frequency lower than the cutoff frequency will attenuate, rather than ...
Alpha cutoff frequency, or is the frequency at which the common base DC current gain drops to 0.707 of its low frequency value. The common base DC current gain is the ratio of a transistor's collector current to the transistor's emitter current , or α = i C i E {\displaystyle \alpha ={\frac {i_{C}}{i_{E}}}} .
The half-power point is the point at which the output power has dropped to half of its peak value; that is, at a level of approximately −3 dB. [1] [a]In filters, optical filters, and electronic amplifiers, [2] the half-power point is also known as half-power bandwidth and is a commonly used definition for the cutoff frequency.
where is the wavelength expressed in millimeters and F # is the lens' focal ratio. As an example, a telescope having an f /6 objective and imaging at 0.55 micrometers has a spatial cutoff frequency of 303 cycles/millimeter. High-resolution black-and-white film is capable of resolving details on the film as small as 3 micrometers or smaller ...
Figure 2 illustrates the approximation. The x-axis is the ratio τ 1 / τ 2 on a logarithmic scale. An increase in this variable means the higher pole is further above the corner frequency. The y-axis is the ratio of the OCTC (open-circuit time constant) estimate to the true time constant.
In digital signal processing (DSP), a normalized frequency is a ratio of a variable frequency and a constant frequency associated with a system (such as a sampling rate, ). Some software applications require normalized inputs and produce normalized outputs, which can be re-scaled to physical units when necessary.
The response value of the Gaussian filter at this cut-off frequency equals exp(−0.5) ≈ 0.607. However, it is more common to define the cut-off frequency as the half power point: where the filter response is reduced to 0.5 (−3 dB) in the power spectrum, or 1/ √ 2 ≈ 0.707 in the amplitude spectrum (see e.g. Butterworth filter ).