import logging
import numpy as np
from kwave.kmedium import kWaveMedium
from kwave.options.simulation_options import SimulationType
[docs]
def set_sound_speed_ref(medium: kWaveMedium, simulation_type: SimulationType):
"""
select the reference sound speed used in the k-space operator
based on the heterogeneous sound speed map
Args:
medium: kWaveMedium object
simulation_type: Simulation type (fluid, axisymmetric, elastic, elastic with k-space correction)
Returns:
"""
if not simulation_type.is_elastic_simulation():
return get_ordinary_sound_speed_ref(medium)
elif simulation_type == SimulationType.ELASTIC: # pragma: no cover
return get_pstd_elastic_sound_speed_ref(medium)
elif simulation_type == SimulationType.ELASTIC_WITH_KSPACE_CORRECTION: # pragma: no cover
return get_kspace_elastic_sound_speed_ref(medium)
else:
raise NotImplementedError("Non-supported simulation type: " + str(simulation_type))
[docs]
def get_ordinary_sound_speed_ref(medium):
"""
calculate the reference sound speed for the fluid code, using the
maximum by default which ensures the model is unconditionally stable
Args:
medium:
Returns:
"""
c_ref = _get_sound_speed_ref(medium.sound_speed_ref, medium.sound_speed)
logging.log(logging.INFO, ' reference sound speed: ', c_ref, 'm/s')
return c_ref, None, None
[docs]
def get_pstd_elastic_sound_speed_ref(medium: kWaveMedium): # pragma: no cover
"""
in the pstd elastic case, the reference sound speed is only used to
calculate the PML absorption, so just use the compressional wave speed
Args:
medium:
Returns:
"""
c_ref = _get_sound_speed_ref(medium.sound_speed_ref, medium.sound_speed_compression)
logging.log(logging.INFO, ' reference sound speed: ', c_ref, 'm/s')
return c_ref, None, None
[docs]
def get_kspace_elastic_sound_speed_ref(medium: kWaveMedium): # pragma: no cover
"""
in the k-space elastic case, there are two reference sound speeds for
the compressional and shear waves, so compute them seperately
Args:
medium:
Returns:
"""
c_ref_compression = _get_sound_speed_ref(medium.sound_speed_ref_compression, medium.sound_speed_compression)
logging.log(logging.INFO, ' reference sound speed (compression): ', c_ref_compression, 'm/s')
c_ref_shear = _get_sound_speed_ref(medium.sound_speed_ref_shear, medium.sound_speed_shear)
logging.log(logging.INFO, ' reference sound speed (shear): ', c_ref_shear, 'm/s')
return None, c_ref_compression, c_ref_shear
def _get_sound_speed_ref(reference, speed):
reductions = {
'min': np.min,
'max': np.max,
'mean': np.mean
}
if reference is not None:
# if reference is defined, check whether it is a scalar or 'reduction'
if np.isscalar(reference):
c_ref = reference
else:
c_ref = reductions[reference](speed)
else:
c_ref = reductions['max'](speed)
logging.log(logging.INFO, ' reference sound speed: ', c_ref, 'm/s')
return float(c_ref)