Determination of optical radiation attenuation in dispersed system «coal dust-air»

A Wavelength-Dependent Visible Light Communication Channel Model for Underground Environments and Its Performance Using a Color-Shift Keying Modulation Scheme

“…When wavelength and particle size are comparable, Mie scattering theory is more accurate, and when α 1, then geometric scattering theory is used [30]. The particle size distribution of airborne particles in underground mines varies depending on the extractive activity, mineral composition, and geology of the mine, but a generalization can be made by looking at several studies conducted in underground coal mines in the United States [31,32], China [30,33], and the former Soviet Union [34] and underground gold mines in Alaska, Nevada, and South Africa [35], all of which show that the particle sizes of coal and silica dust particle sizes are in the order of 1 µm to 100 µm. Taking into account the wavelengths in the visible spectrum, this range of particle sizes implies that α takes values in the order of 1 to 10 3 : that means that Mie theory is the preferred regime for describing the scattering and absorption phenomena in underground mines.…”

“…The authors in [30] use the R-R distribution in their calculations of the extinction coefficient of coal dust in underground mines. The authors in [34] also argue that mine dust is best described by the R-R method. Assuming mine dust follows the R-R distribution, then F(x p ) can be expressed as [30,40]:…”

“…The dust was assumed to be coal dust, with a refractive index taken from [30], found empirically in a coal mine in China, and presented in Figure 4e. The particle size distribution parameters of the coal dust were taken from [34], where empirical data from coal mines in the former Soviet Union were used. The work of [34] presents a wide range of possible coal dust concentrations based on different activities in the mine.…”

“…The particle size distribution parameters of the coal dust were taken from [34], where empirical data from coal mines in the former Soviet Union were used. The work of [34] presents a wide range of possible coal dust concentrations based on different activities in the mine. A concentration of W p = 5000 mg/m 3 was selected, which is about the highest concentration that can be obtained in coal mines without dust prevention measures according to [30] and is much higher than the maximum of 4 mg/m 3 defined by the China National Health and Wellness Committee [30].…”

“…A concentration of W p = 5000 mg/m 3 was selected, which is about the highest concentration that can be obtained in coal mines without dust prevention measures according to [30] and is much higher than the maximum of 4 mg/m 3 defined by the China National Health and Wellness Committee [30]. However, [34] reports dust concentrations of up to 30 g/m 3 under certain mining activities. We use this high concentration value in the simulations to better exemplify the effect of dust in the communication channel.…”