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In the table, the first column gives the results in dB, the third gives the distance covered and the last gives the final altitude. Distances are in km. From the altitude 30 km up, the attenuation is negligible. The paths of the three are plotted: Note: A MATLAB version for the uplink (Telecommunications link) is available from the ITU [2]
μ is sometimes called Napierian attenuation coefficient or Napierian narrow beam attenuation coefficient rather than just simply "attenuation coefficient". The terms "decadic" and "Napierian" come from the base used for the exponential in the Beer–Lambert law for a material sample, in which the two attenuation coefficients take part:
where is a random number and is the total interaction coefficient (i.e., the sum of the absorption and scattering coefficients). Once a step size is selected, the photon packet is propagated by a distance s in a direction defined by the direction cosines. This is easily accomplished by simply updating the coordinates as follows:
A standard linear solid Q model (SLS) for attenuation and dispersion is one of many mathematical Q models that gives a definition of how the earth responds to seismic waves. When a plane wave propagates through a homogeneous viscoelastic medium, the effects of amplitude attenuation and velocity dispersion may be combined conveniently into a ...
A set of many such projections under different angles organized in 2D is called a sinogram (see Fig. 3). In X-ray CT, the line integral represents the total attenuation of the beam of X-rays as it travels in a straight line through the object. As mentioned above, the resulting image is a 2D (or 3D) model of the attenuation coefficient.
A requirement in the theory for materials satisfying the linear attenuation assumption is that the reference frequency w r is a finite (arbitrarily small but nonzero) cut-off on the absorption. According to Kolsky, we are free to choose w r following the phenomenological criterion that it be small compared with the lowest measured frequency w ...
Step 5: Create the B vector for the linear equations by subtracting the target values at each frequency, which in this case are all 1 due to the cutoff attenuation being equal to the pass band ripple attenuation in this specific example.
In those situations, the most general form of the Beer–Lambert law states that the total attenuation can be obtained by integrating the attenuation coefficient over small slices dz of the beamline: = = (), = = (). These formulations then reduce to the simpler versions when there is only one active species and the attenuation coefficients are ...