Bloch wave – MoM method the wave numbers in any of the 3 periodic coordinate directions. This can happen for example when the free space wavelength exactly equals the lattice spacing. This is a statistically rare occurrence in computational practice and corresponds to a propagation anomaly similar to a Wood's reflection anomaly for gratings. To compute bands of the crystal (i.e. "k"-"k" diagrams), successive values of frequency ("k") are tried - in conjunction with pre-selected values of propagation constant ("k") and propagation direction (θ & φ) - until a combination is found which drives the determinant of the matrix to zero. Equation (4.2) has been
Sound power temperature, the sound power level at distance "r" from the sound source is approximately related to sound pressure level (SPL) by where Derivation of this equation: For a "progressive" spherical wave, where "z" is the characteristic specific acoustic impedance. Consequently, and since by definition , where is the reference sound pressure, The sound power estimated practically does not depend on distance. The sound pressure used in the calculation may be affected by distance due to viscous effects in the propagation of sound unless this is accounted for. Sound power Sound power or acoustic power is the rate at which sound