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
Coda Wave Interferometry The unperturbed travel time is given by formula_8 where formula_9 is the coda wave velocity. The perturbed travel time is formula_10 where formula_11 is the velocity perturbation. Thus formula_12 . If the relative velocity perturbation is assumed constant, then formula_13 where t is the center time of the employed time window. Thus, the travel time perturbation depends on the arrival time of the coda wave, but not of the particular path followed. Coda Wave Interferometry Coda Wave Interferometry is an ultrasound technique for detection of weak and local changes in complex inhomogeneous media. Sound waves that travel through a medium