def run(plotIt=True):
"""
1D FDEM Mu Inversion
====================
1D inversion of Magnetic Susceptibility from FDEM data assuming a fixed
electrical conductivity
"""
# Set up cylindrically symmeric mesh
cs, ncx, ncz, npad = 10., 15, 25, 13 # padded cyl mesh
hx = [(cs, ncx), (cs, npad, 1.3)]
hz = [(cs, npad, -1.3), (cs, ncz), (cs, npad, 1.3)]
mesh = Mesh.CylMesh([hx, 1, hz], '00C')
# Geologic Parameters model
layerz = np.r_[-100., -50.]
layer = (mesh.vectorCCz >= layerz[0]) & (mesh.vectorCCz <= layerz[1])
active = mesh.vectorCCz < 0.
# Electrical Conductivity
sig_half = 1e-2 # Half-space conductivity
sig_air = 1e-8 # Air conductivity
sig_layer = 1e-2 # Layer conductivity
sigma = np.ones(mesh.nCz) * sig_air
sigma[active] = sig_half
sigma[layer] = sig_layer
# mur - relative magnetic permeability
mur_half = 1.
mur_air = 1.
mur_layer = 2.
mur = np.ones(mesh.nCz) * mur_air
mur[active] = mur_half
mur[layer] = mur_layer
mtrue = mur[active]
# Maps
actMap = Maps.InjectActiveCells(mesh, active, mur_air, nC=mesh.nCz)
surj1Dmap = Maps.SurjectVertical1D(mesh)
murMap = Maps.MuRelative(mesh)
# Mapping
muMap = murMap * surj1Dmap * actMap
# ----- FDEM problem & survey -----
rxlocs = Utils.ndgrid([np.r_[10.], np.r_[0], np.r_[30.]])
bzr = FDEM.Rx.Point_bSecondary(rxlocs, 'z', 'real')
# bzi = FDEM.Rx.Point_bSecondary(rxlocs, 'z', 'imag')
freqs = np.linspace(2000, 10000, 10) #np.logspace(3, 4, 10)
srcLoc = np.array([0., 0., 30.])
print('min skin depth = ', 500. / np.sqrt(freqs.max() * sig_half),
'max skin depth = ', 500. / np.sqrt(freqs.min() * sig_half))
print('max x ', mesh.vectorCCx.max(), 'min z ', mesh.vectorCCz.min(),
'max z ', mesh.vectorCCz.max())
srcList = [
FDEM.Src.MagDipole([bzr], freq, srcLoc, orientation='Z')
for freq in freqs
]
surveyFD = FDEM.Survey(srcList)
prbFD = FDEM.Problem3D_b(mesh,
sigma=surj1Dmap * sigma,
muMap=muMap,
Solver=Solver)
prbFD.pair(surveyFD)
std = 0.03
surveyFD.makeSyntheticData(mtrue, std)
surveyFD.eps = np.linalg.norm(surveyFD.dtrue) * 1e-6
# FDEM inversion
np.random.seed(13472)
dmisfit = DataMisfit.l2_DataMisfit(surveyFD)
regMesh = Mesh.TensorMesh([mesh.hz[muMap.maps[-1].indActive]])
reg = Regularization.Simple(regMesh)
opt = Optimization.InexactGaussNewton(maxIterCG=10)
invProb = InvProblem.BaseInvProblem(dmisfit, reg, opt)
# Inversion Directives betaest = Directives.BetaEstimate_ByEig(beta0_ratio=2.)
beta = Directives.BetaSchedule(coolingFactor=4, coolingRate=3)
betaest = Directives.BetaEstimate_ByEig(beta0_ratio=2.)
target = Directives.TargetMisfit()
directiveList = [beta, betaest, target]
inv = Inversion.BaseInversion(invProb, directiveList=directiveList)
m0 = mur_half * np.ones(mtrue.size)
reg.alpha_s = 2e-2
reg.alpha_x = 1.
prbFD.counter = opt.counter = Utils.Counter()
opt.remember('xc')
moptFD = inv.run(m0)
dpredFD = surveyFD.dpred(moptFD)
if plotIt:
fig, ax = plt.subplots(1, 3, figsize=(10, 6))
fs = 13 # fontsize
matplotlib.rcParams['font.size'] = fs
# Plot the conductivity model
ax[0].semilogx(sigma[active], mesh.vectorCCz[active], 'k-', lw=2)
ax[0].set_ylim(-500, 0)
ax[0].set_xlim(5e-3, 1e-1)
ax[0].set_xlabel('Conductivity (S/m)', fontsize=fs)
ax[0].set_ylabel('Depth (m)', fontsize=fs)
ax[0].grid(which='both',
color='k',
alpha=0.5,
linestyle='-',
linewidth=0.2)
ax[0].legend(['Conductivity Model'], fontsize=fs, loc=4)
# Plot the permeability model
ax[1].plot(mur[active], mesh.vectorCCz[active], 'k-', lw=2)
ax[1].plot(moptFD, mesh.vectorCCz[active], 'b-', lw=2)
ax[1].set_ylim(-500, 0)
ax[1].set_xlim(0.5, 2.1)
ax[1].set_xlabel('Relative Permeability', fontsize=fs)
ax[1].set_ylabel('Depth (m)', fontsize=fs)
ax[1].grid(which='both',
color='k',
alpha=0.5,
linestyle='-',
linewidth=0.2)
ax[1].legend(['True', 'Predicted'], fontsize=fs, loc=4)
# plot the data misfits - negative b/c we choose positive to be in the
# direction of primary
ax[2].plot(freqs, -surveyFD.dobs, 'k-', lw=2)
# ax[2].plot(freqs, -surveyFD.dobs[1::2], 'k--', lw=2)
ax[2].loglog(freqs, -dpredFD, 'bo', ms=6)
# ax[2].loglog(freqs, -dpredFD[1::2], 'b+', markeredgewidth=2., ms=10)
# Labels, gridlines, etc
ax[2].grid(which='both', alpha=0.5, linestyle='-', linewidth=0.2)
ax[2].grid(which='both', alpha=0.5, linestyle='-', linewidth=0.2)
ax[2].set_xlabel('Frequency (Hz)', fontsize=fs)
ax[2].set_ylabel('Vertical magnetic field (-T)', fontsize=fs)
# ax[2].legend(("Obs", "Pred"), fontsize=fs)
ax[2].legend(("z-Obs (real)", "z-Pred (real)"), fontsize=fs)
ax[2].set_xlim(freqs.max(), freqs.min())
ax[0].set_title("(a) Conductivity Model", fontsize=fs)
ax[1].set_title("(b) $\mu_r$ Model", fontsize=fs)
ax[2].set_title("(c) FDEM observed vs. predicted", fontsize=fs)
# ax[2].set_title("(c) TDEM observed vs. predicted", fontsize=fs)
plt.tight_layout(pad=1.5)
def setupProblem(
mesh, muMod, sigmaMod, prbtype='e', invertMui=False,
sigmaInInversion=False, freq=1.
):
rxcomp = ['real', 'imag']
loc = Utils.ndgrid(
[mesh.vectorCCx, np.r_[0.], mesh.vectorCCz]
)
if prbtype in ['e', 'b']:
rxfields_y = ['e', 'j']
rxfields_xz = ['b', 'h']
elif prbtype in ['h', 'j']:
rxfields_y = ['b', 'h']
rxfields_xz = ['e', 'j']
rxList_edge = [
getattr(FDEM.Rx, 'Point_{f}'.format(f=f))(
loc, component=comp, orientation=orient
)
for f in rxfields_y
for comp in rxcomp
for orient in ['y']
]
rxList_face = [
getattr(FDEM.Rx, 'Point_{f}'.format(f=f))(
loc, component=comp, orientation=orient
)
for f in rxfields_xz
for comp in rxcomp
for orient in ['x', 'z']
]
rxList = rxList_edge + rxList_face
src_loc = np.r_[0., 0., 0.]
if prbtype in ['e', 'b']:
src = FDEM.Src.MagDipole(
rxList=rxList, loc=src_loc, freq=freq
)
elif prbtype in ['h', 'j']:
ind = Utils.closestPoints(mesh, src_loc, 'Fz') + mesh.vnF[0]
vec = np.zeros(mesh.nF)
vec[ind] = 1.
src = FDEM.Src.RawVec_e(rxList=rxList, freq=freq, s_e=vec)
survey = FDEM.Survey([src])
if sigmaInInversion:
wires = Maps.Wires(
('mu', mesh.nC),
('sigma', mesh.nC)
)
muMap = Maps.MuRelative(mesh) * wires.mu
sigmaMap = Maps.ExpMap(mesh) * wires.sigma
if invertMui:
muiMap = Maps.ReciprocalMap(mesh)*muMap
prob = getattr(FDEM, 'Problem3D_{}'.format(prbtype))(
mesh, muiMap=muiMap, sigmaMap=sigmaMap
)
# m0 = np.hstack([1./muMod, sigmaMod])
else:
prob = getattr(FDEM, 'Problem3D_{}'.format(prbtype))(
mesh, muMap=muMap, sigmaMap=sigmaMap
)
m0 = np.hstack([muMod, sigmaMod])
else:
muMap = Maps.MuRelative(mesh)
if invertMui:
muiMap = Maps.ReciprocalMap(mesh) * muMap
prob = getattr(FDEM, 'Problem3D_{}'.format(prbtype))(
mesh, sigma=sigmaMod, muiMap=muiMap
)
# m0 = 1./muMod
else:
prob = getattr(FDEM, 'Problem3D_{}'.format(prbtype))(
mesh, sigma=sigmaMod, muMap=muMap
)
m0 = muMod
prob.pair(survey)
return m0, prob, survey
