Acknowledgements |
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xv | |
List of selected symbols |
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xvii | |
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1 | (6) |
Part I Mathematical-Physical Model |
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2 Basic mathematical-physical model |
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7 | (11) |
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7 | (1) |
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2.2 Governing equation: equation of motion |
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8 | (3) |
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9 | (1) |
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10 | (1) |
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2.2.3 Integral strong form |
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11 | (1) |
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11 | (1) |
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2.3 Constitutive law: stress-strain relation |
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11 | (2) |
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12 | (1) |
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2.3.2 Viscoelastic continuum |
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13 | (1) |
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2.4 Strong-form formulations of equations |
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13 | (3) |
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2.4.1 Displacement-stress formulation |
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14 | (1) |
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2.4.2 Displacement formulation |
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14 | (1) |
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2.4.3 Displacement-velocity-stress formulation |
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14 | (1) |
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2.4.4 Velocity-stress formulation |
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14 | (2) |
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16 | (1) |
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16 | (1) |
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2.5.2 Welded material interface |
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16 | (1) |
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17 | (1) |
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2.7 Wavefield source (wavefield excitation) |
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17 | (1) |
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3 Rheological models of a continuum |
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18 | (40) |
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3.1 Basic rheological models |
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20 | (3) |
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3.1.1 Hooke elastic solid . |
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20 | (2) |
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3.1.2 Newton viscous liquid |
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22 | (1) |
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3.1.3 Saint-Venant plastic solid |
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22 | (1) |
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3.2 Combined rheological models |
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23 | (1) |
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3.3 Viscoelastic continuum and its rheological models |
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23 | (23) |
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3.3.1 Stress-strain and strain-stress relations in a viscoelastic continuum |
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24 | (3) |
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3.3.2 Maxwell and Kelvin-Voigt bodies |
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27 | (1) |
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3.3.3 Zener body (standard linear solid) |
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27 | (4) |
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3.3.4 Phase velocity in elastic and viscoelastic continua |
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31 | (2) |
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3.3.5 Measure of dissipation and attenuation in a viscoelastic continuum |
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33 | (2) |
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3.3.6 Attenuation in Zener body |
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35 | (1) |
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3.3.7 Generalized Zener body (GZB) |
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35 | (3) |
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3.3.8 Generalized Maxwell body (GMB-EK) |
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38 | (1) |
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3.3.9 Equivalence of GZB and GMB-EK |
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39 | (1) |
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3.3.10 Anelastic functions (memory variables) |
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40 | (3) |
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3.3.11 Anelastic coefficients and unrelaxed modulus |
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43 | (1) |
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3.3.12 Attenuation and phase velocity in GMB-EK/GZB continuum |
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44 | (1) |
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3.3.13 Stress-strain relation in 3D |
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45 | (1) |
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3.4 Elastoplastic continuum |
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46 | (12) |
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3.4.1 Simplest elastoplastic bodies |
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47 | (3) |
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3.4.2 Iwan elastoplastic model for hysteretic stress-strain behaviour |
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50 | (8) |
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58 | (15) |
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4.1 Dynamic model of an earthquake source |
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59 | (5) |
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4.1.1 Boundary conditions for dynamic shear faulting |
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60 | (1) |
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61 | (3) |
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4.2 Kinematic model of an earthquake source |
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64 | (9) |
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65 | (3) |
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4.2.2 Finite-fault kinematic source |
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68 | (5) |
Part II The Finite-Difference Method |
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5 Time-domain numerical methods |
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73 | (10) |
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73 | (1) |
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5.2 Fourier pseudo-spectral method |
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74 | (2) |
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5.3 Spectral element method |
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76 | (3) |
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5.4 Spectral discontinuous Galerkin scheme with ADER time integration |
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79 | (2) |
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81 | (2) |
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6 Brief introduction to the finite-difference method |
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83 | (14) |
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83 | (3) |
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83 | (1) |
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6.1.2 Uniform, nonuniform and discontinuous grids |
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84 | (1) |
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6.1.3 Structured and unstructured grids |
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84 | (1) |
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6.1.4 Space-time locations of field variables |
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84 | (2) |
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6.2 FD approximations based on Taylor series |
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86 | (7) |
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6.2.1 Simple approximations |
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86 | (2) |
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6.2.2 Combined approximations: convolution |
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88 | (2) |
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6.2.3 Approximations applied to a harmonic wave |
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90 | (1) |
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6.2.4 General note on the FD approximations |
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91 | (2) |
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6.3 Explicit and implicit FD schemes |
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93 | (1) |
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6.4 Basic properties of FD schemes |
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94 | (2) |
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6.5 Approximations based on dispersion-relation-preserving criterion |
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96 | (1) |
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97 | (69) |
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7.1 Equation of motion and the stress-strain relation |
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97 | (2) |
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7.2 A simple FD scheme: a tutorial introduction to FD schemes |
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99 | (24) |
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7.2.1 Plane harmonic wave in a physical continuum |
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100 | (1) |
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7.2.2 Plane harmonic wave in a grid |
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100 | (1) |
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7.2.3 (2,2) 1D FD scheme on a conventional grid |
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101 | (2) |
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7.2.4 Analysis of grid-dispersion relations |
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103 | (11) |
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7.2.5 Summary of the identified partial regimes |
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114 | (1) |
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7.2.6 Grid phase and group velocities |
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115 | (4) |
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119 | (2) |
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7.2.8 Sufficiently accurate numerical simulation |
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121 | (2) |
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7.3 FD schemes for an unbounded smoothly heterogeneous medium |
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123 | (28) |
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7.3.1 (2,2) displacement scheme on a conventional grid |
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123 | (2) |
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7.3.2 (2,2) displacement-stress scheme on a spatially staggered grid |
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125 | (2) |
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7.3.3 (2,2) velocity-stress scheme on a staggered grid |
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127 | (2) |
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7.3.4 Optimally accurate displacement scheme on a conventional grid |
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129 | (4) |
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7.3.5 (2,4) and (4,4) velocity-stress schemes on a staggered grid |
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133 | (11) |
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7.3.6 (4,4) velocity-stress schemes on a collocated grid |
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144 | (7) |
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7.4 FD schemes for a material interface |
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151 | (4) |
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7.4.1 Simple general consideration |
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152 | (1) |
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7.4.2 Hooke's law and equation of motion for a welded interface |
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153 | (1) |
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7.4.3 Simple rheological model of a welded interface |
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154 | (1) |
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154 | (1) |
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7.5 FD schemes for a free surface |
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155 | (3) |
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156 | (1) |
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7.5.2 Adjusted FD approximations |
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157 | (1) |
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7.6 Boundaries of a spatial grid |
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158 | (3) |
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7.6.1 Perfectly matched layer: theory |
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159 | (1) |
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7.6.2 Perfectly matched layer: scheme |
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160 | (1) |
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161 | (2) |
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7.7.1 Body-force term and incremental stress |
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162 | (1) |
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7.7.2 Wavefield injection based on wavefield decomposition |
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162 | (1) |
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7.8 FD scheme for the anelastic functions for a smooth medium |
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163 | (3) |
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8 3D finite-difference schemes |
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166 | (33) |
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8.1 Formulations and grids |
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166 | (4) |
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8.1.1 Displacement conventional-grid schemes |
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166 | (1) |
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8.1.2 Velocity-stress staggered-grid schemes |
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167 | (1) |
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8.1.3 Displacement-stress schemes on the grid staggered in space |
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168 | (1) |
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8.1.4 Velocity-stress partly-staggered-grid schemes |
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168 | (1) |
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8.1.5 Optimally accurate schemes |
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169 | (1) |
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8.1.6 Velocity-stress schemes on the collocated grid |
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170 | (1) |
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8.2 Schemes on staggered, partly-staggered, collocated and conventional grids |
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170 | (6) |
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8.2.1 (2,4) velocity-stress scheme on the staggered grid |
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171 | (1) |
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8.2.2 (2,4) velocity-stress scheme on the partly-staggered grid |
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172 | (3) |
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8.2.3 (4,4) velocity-stress scheme on the collocated grid |
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175 | (1) |
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8.2.4 Disp1a"&ment scheme on the conventional grid |
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175 | (1) |
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8.3 Accuracy of FD schemes with respect to P-wave to S-wave speed ratio: analysis of local errors |
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176 | (17) |
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8.3.1 Equations and FD schemes |
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176 | (6) |
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182 | (1) |
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8.3.3 The exact and numerical values of displacement in a grid |
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183 | (2) |
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8.3.4 Equivalent spatial sampling for the errors in amplitude and the vector difference |
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185 | (2) |
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8.3.5 Essential summary based on the numerical investigation |
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187 | (1) |
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8.3.6 Interpretation of the errors |
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187 | (5) |
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192 | (1) |
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8.4 Stability and grid dispersion of the VS SG (2,4) scheme |
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193 | (6) |
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9 Velocity-stress staggered-grid scheme for an unbounded heterogeneous viscoelastic medium |
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199 | (18) |
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9.1 FD modelling of a material interface |
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199 | (3) |
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9.2 Stress-strain relation at a material interface |
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202 | (8) |
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9.2.1 Planar interface parallel to a coordinate plane |
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203 | (2) |
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9.2.2 Planar interface in a general orientation |
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205 | (1) |
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9.2.3 Effective orthorhombic averaged medium |
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206 | (2) |
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9.2.4 Effective grid density |
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208 | (1) |
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9.2.5 Simplified approach with harmonic averaging of elastic moduli: isotropic averaged medium |
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209 | (1) |
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9.3 Incorporation of realistic attenuation |
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210 | (7) |
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9.3.1 Material interface in a viscoelastic medium |
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210 | (1) |
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9.3.2 Scheme for the anelastic functions for an isotropic averaged medium |
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211 | (1) |
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9.3.3 Scheme for the anelastic functions for an orthorhombic averaged medium |
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212 | (1) |
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9.3.4 Coarse spatial distribution of anelastic functions |
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213 | (2) |
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9.3.5 VS SG (2,4) scheme for a heterogeneous viscoelastic medium |
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215 | (2) |
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10 Schemes for a free surface |
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217 | (10) |
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217 | (6) |
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10.1.1 Stress imaging in the (2,4) VS SG scheme |
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218 | (3) |
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10.1.2 Adjusted FD approximations in the (2,4) VS SG scheme |
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221 | (2) |
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10.2 Free-surface topography |
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223 | (4) |
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11 Discontinuous spatial grid |
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227 | (7) |
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11.1 Overview of approaches |
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227 | (2) |
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11.2 Two basic problems and general considerations |
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229 | (1) |
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11.3 Velocity-stress discontinuous staggered grid |
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230 | (4) |
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11.3.1 Calculation of the field variables at the boundary of the finer grid in the overlapping zone |
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230 | (1) |
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11.3.2 Calculation of the field variables at the boundary of the coarser grid in the overlapping zone |
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231 | (2) |
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11.3.3 Calculation of the field variables at the nonreflecting boundary |
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233 | (1) |
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12 Perfectly matched layer |
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234 | (8) |
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12.1 Split formulation of the PML |
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235 | (3) |
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12.2 Unsplit formulation of the PML |
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238 | (1) |
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12.3 Summary of the formulations |
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239 | (1) |
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12.4 Time discretization of the unsplit formulation |
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239 | (3) |
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13 Simulation of the kinematic sources |
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242 | (4) |
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13.1 Wavefield decomposition |
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242 | (1) |
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242 | (3) |
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245 | (1) |
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14 Simulation of dynamic rupture propagation |
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246 | (13) |
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14.1 Traction-at-split-node method |
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247 | (5) |
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14.2 Implementation of TSN in the staggered-grid scheme |
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252 | (4) |
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14.3 Initiation of spontaneous rupture propagation |
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256 | (3) |
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15 Preparation of computations and a computational algorithm |
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259 | (4) |
Part III Finite-Element Method And Hybrid Finite-Difference-finite-Element Method |
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263 | (22) |
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16.1 Weak form of the equation of motion |
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263 | (2) |
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16.2 Discrete weak form of the equation of motion for an element |
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265 | (2) |
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267 | (6) |
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16.4 FE scheme for an element using the local restoring-force vector |
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273 | (5) |
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16.5 FE scheme for the whole domain using the global restoring-force vector |
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278 | (4) |
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16.6 Efficient computation of the restoring-force vector |
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282 | (1) |
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16.7 Comparison of formulations with the restoring force and stiffness matrix |
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283 | (1) |
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16.8 Essential summary of the FEM implementation |
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284 | (1) |
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17 Traction-at-split-node modelling of dynamic rupture propagation |
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285 | (10) |
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17.1 Implementation of TSN in the FEM |
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285 | (3) |
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17.2 Spurious high-frequency oscillations of the slip rate |
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288 | (2) |
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17.3 Approaches to suppress high-frequency oscillations |
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290 | (5) |
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17.3.1 Adaptive smoothing |
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290 | (2) |
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17.3.2 Kelvin-Voigt damping |
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292 | (1) |
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17.3.3 A-posteriori filtration |
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293 | (2) |
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18 Hybrid finite-difference-finite-element method |
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295 | (12) |
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18.1 Computational domain |
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295 | (1) |
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18.2 Principle of the FD-FE causal communication |
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296 | (1) |
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18.3 Smooth transition zone with FD-FE averaging |
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297 | (2) |
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18.4 Illustrative numerical simulations using hybrid FD-FE method |
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299 | (1) |
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18.5 Potential improvement of the hybrid FD-FE method |
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300 | (7) |
Part IV Finite-Difference Modelling Of Seismic Motion At Real Sites |
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19 Modelling of earthquake motion: Mygdonian basin |
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307 | (20) |
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19.1 Modelling of earthquake motion and real earthquakes by the FDM |
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307 | (1) |
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19.2 Mygdonian basin near Thessaloniki, Greece |
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308 | (19) |
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19.2.1 Why the Mygdonian basin? - the E2VP |
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308 | (1) |
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19.2.2 The realistic model and implied challenges |
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309 | (3) |
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19.2.3 Comparative modelling for stringent canonical models |
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312 | (8) |
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19.2.4 Modelling for the realistic three-layered viscoelastic model |
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320 | (2) |
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19.2.5 Lessons learned from ESG 2006and E2VP |
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322 | (2) |
Concluding remarks: search for the best scheme |
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324 | (3) |
Appendix A: Time-frequency misfit and goodness-of-fit criteria for quantitative comparison of time signals |
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327 | (8) |
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A.1 Characterization of a signal |
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327 | (2) |
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A.1.1 Simplest characteristics |
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327 | (1) |
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A.1.2 Time-frequency decomposition |
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328 | (1) |
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A.2 Comparison of signals |
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329 | (1) |
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A.2.1 TF envelope and phase differences |
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329 | (1) |
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A.2.2 Locally normalized and globally normalized criteria |
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329 | (1) |
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A.3 Comparison of three-component signals |
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330 | (5) |
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331 | (1) |
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A.3.2 TF goodness-of-fit criteria |
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331 | (4) |
References |
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335 | (28) |
Index |
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