Attenuation Coefficient

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attenuation coefficient

[ə‚ten·yə′wā·shən ‚kō·ə′fish·ənt]

(electromagnetism)

The space rate of attenuation of any transmitted electromagnetic radiation.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Attenuation Coefficient

(or extinction coefficient), a quantity inverse to the distance at which the radiation flux forming a parallel beam is attenuated as a result of the joint action of the absorption and scattering of light in a medium by a specified factor. When the factor is 10, the coefficient is called the decimal attenuation coefficient, and when the factor is e, it is called the natural attenuation coefficient. The attenuation coefficient is the sum of the absorption coefficient and the scattering coefficient of the medium. These coefficients depend on the set of frequencies v, or wavelengths λ, that characterize the initial flux. The value of the attenuation coefficient for the limiting case of a single frequency v is called the monochromatic attenuation coefficient. Like the absorption and scattering coefficients, the attenuation coefficient can be divided by the volume of the medium or by the mass of the attenuating substance; we shall call these two ratios the volume and mass attenuation coefficients, respectively.

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Measurements of the effective attenuation coefficient were reported by Davis [18] in his extensive study of the dosimetry of these sources.

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Figure 5 shows the variation of attenuation coefficient with respect to the wave number for different value of thickness of the layer.

Effect of initial stress on the propagation characteristics of waves in fiber-reinforced transversely isotropic thermoelastic material under an inviscid liquid layer

Figure 10 displays the variation of the Stoneley wave velocity and attenuation coefficient with respect to phase velocity c that has oscillatory behavior in the whole range of c for L-S theory, which changes from the positive to the negative gradually.

Effects of rotation and gravity field on surface waves in fibre-reinforced thermoelastic media under four theories

In the interaction of photon with matter, the total mass attenuation coefficient ([[mu].sub.t]) values are dependent on the physical and chemical environments of the samples.

Photon atomic parameters of nonessential amino acids for radiotherapy and diagnostics

Soil Mass Attenuation Coefficient. In Table 1 the [[rho].sub.s] values calculated (XCOM) and measured as well as the relative differences amongst them are presented.

Representative elementary length to measure soil mass attenuation coefficient

* Attenuation coefficient (a) of methyl acetate at 27 [degrees]C (Expt.) = 0.

Absorption studies of binary mixtures

For V101 transmitter, using Pico or [micro]30 receiver, we found the attenuation coefficient (damping factor), [alpha], to be as below in Np/m:

Attenuation of lamb waves in CFRP plates

(10, 11) have indicated that as both total attenuation coefficient and ambient temperature increase, the signal to noise ratio decreases at constant optical link range.

Upgrading efficiency and improvement of the performance of broadband wireless optical access communication networks

We used the results of the underwater quantum irradiance for estimating the widely used diffuse attenuation coefficient, [K.sub.d](PAR) (Dera 1992; Kirk 1994; Arst 2003).

Optical investigations of CDOM-rich coastal waters in Parnu Bay/Optilised mootmised lahustunud orgaanilise aine rikastes Parnu lahe rannikuvetes

The contributions of chl-a ([micro]g [L.sup.-1]) and CDOM ([a.sub.320]) to the attenuation coefficient were then calculated as:

Plankton dynamics and photosynthesis responses in a eutrophic lake in Patagonia (Argentina): influence of grazer abundance and UVR/Dinamica del plancton y respuestas fotosinteticas en una laguna eutrofica de Patagonia (Argentina): influencia de la abundancia de herbivoros y RUV

Our results showed that a model incorporating daily variation of incoming PAR irradiance combined with episodic measurements of chlorophyll a concentration and diffuse attenuation coefficient in the water was suitable for estimating variation of the primary production in lakes.

Foreword

The optical parameter, best used to describe the worsening of light conditions due to sediment resuspension, is the diffuse attenuation coefficient [K.sub.d] (PAR), calculated from the underwater irradiation data as

Monitoring wave-induced sediment resuspension/Lainete pohjustatud setete resuspensiooni seire