def setUp_TDEM(prbtype="MagneticFluxDensity", rxcomp="bz", waveform="stepoff"):
cs = 5.0
ncx = 8
ncy = 8
ncz = 8
npad = 4
# hx = [(cs, ncx), (cs, npad, 1.3)]
# hz = [(cs, npad, -1.3), (cs, ncy), (cs, npad, 1.3)]
mesh = discretize.TensorMesh(
[
[(cs, npad, -1.3), (cs, ncx), (cs, npad, 1.3)],
[(cs, npad, -1.3), (cs, ncy), (cs, npad, 1.3)],
[(cs, npad, -1.3), (cs, ncz), (cs, npad, 1.3)],
],
"CCC",
)
active = mesh.vectorCCz < 0.0
activeMap = maps.InjectActiveCells(mesh, active, np.log(1e-8), nC=mesh.nCz)
mapping = maps.ExpMap(mesh) * maps.SurjectVertical1D(mesh) * activeMap
prb = getattr(tdem, "Simulation3D{}".format(prbtype))(mesh,
sigmaMap=mapping)
rxtimes = np.logspace(-4, -3, 20)
if waveform.upper() == "RAW":
out = utils.VTEMFun(prb.times, 0.00595, 0.006, 100)
wavefun = interp1d(prb.times, out)
t0 = 0.006
waveform = tdem.Src.RawWaveform(offTime=t0, waveFct=wavefun)
prb.timeSteps = [(1e-3, 5), (1e-4, 5), (5e-5, 10), (5e-5, 10),
(1e-4, 10)]
rxtimes = t0 + rxtimes
else:
waveform = tdem.Src.StepOffWaveform()
prb.timeSteps = [(1e-05, 10), (5e-05, 10), (2.5e-4, 10)]
rxOffset = 10.0
rx = getattr(tdem.Rx, "Point{}".format(rxcomp[:-1]))(np.r_[rxOffset, 0.0,
-1e-2], rxtimes,
rxcomp[-1])
src = tdem.Src.MagDipole([rx],
loc=np.array([0.0, 0.0, 0.0]),
waveform=waveform)
survey = tdem.Survey([src])
prb.Solver = Solver
m = np.log(1e-1) * np.ones(prb.sigmaMap.nP) + 1e-2 * np.random.rand(
prb.sigmaMap.nP)
prb.pair(survey)
mesh = mesh
return prb, m, mesh
def get_survey(prob, t0):
out = utils.VTEMFun(prob.times, 0.00595, 0.006, 100)
wavefun = interp1d(prob.times, out)
waveform = tdem.Src.RawWaveform(offTime=t0, waveFct=wavefun)
src = tdem.Src.MagDipole([], waveform=waveform, loc=np.array([0.0, 0.0, 0.0]))
return tdem.Survey([src])
def run(plotIt=True):
cs, ncx, ncz, npad = 5.0, 25, 24, 15
hx = [(cs, ncx), (cs, npad, 1.3)]
hz = [(cs, npad, -1.3), (cs, ncz), (cs, npad, 1.3)]
mesh = discretize.CylMesh([hx, 1, hz], "00C")
active = mesh.vectorCCz < 0.0
layer = (mesh.vectorCCz < -50.0) & (mesh.vectorCCz >= -150.0)
actMap = maps.InjectActiveCells(mesh, active, np.log(1e-8), nC=mesh.nCz)
mapping = maps.ExpMap(mesh) * maps.SurjectVertical1D(mesh) * actMap
sig_half = 1e-3
sig_air = 1e-8
sig_layer = 1e-2
sigma = np.ones(mesh.nCz) * sig_air
sigma[active] = sig_half
sigma[layer] = sig_layer
mtrue = np.log(sigma[active])
x = np.r_[30, 50, 70, 90]
rxloc = np.c_[x, x * 0.0, np.zeros_like(x)]
prb = TDEM.Simulation3DMagneticFluxDensity(mesh,
sigmaMap=mapping,
solver=Solver)
prb.time_steps = [
(1e-3, 5),
(1e-4, 5),
(5e-5, 10),
(5e-5, 5),
(1e-4, 10),
(5e-4, 10),
]
# Use VTEM waveform
out = EMutils.VTEMFun(prb.times, 0.00595, 0.006, 100)
# Forming function handle for waveform using 1D linear interpolation
wavefun = interp1d(prb.times, out)
t0 = 0.006
waveform = TDEM.Src.RawWaveform(offTime=t0, waveFct=wavefun)
rx = TDEM.Rx.PointMagneticFluxTimeDerivative(
rxloc,
np.logspace(-4, -2.5, 11) + t0, "z")
src = TDEM.Src.CircularLoop([rx],
waveform=waveform,
loc=np.array([0.0, 0.0, 0.0]),
radius=10.0)
survey = TDEM.Survey([src])
prb.survey = survey
# create observed data
data = prb.make_synthetic_data(mtrue,
relative_error=0.02,
noise_floor=1e-11)
dmisfit = data_misfit.L2DataMisfit(simulation=prb, data=data)
regMesh = discretize.TensorMesh([mesh.hz[mapping.maps[-1].indActive]])
reg = regularization.Simple(regMesh)
opt = optimization.InexactGaussNewton(maxIter=5, LSshorten=0.5)
invProb = inverse_problem.BaseInvProblem(dmisfit, reg, opt)
target = directives.TargetMisfit()
# Create an inversion object
beta = directives.BetaSchedule(coolingFactor=1.0, coolingRate=2.0)
betaest = directives.BetaEstimate_ByEig(beta0_ratio=1e0)
invProb.beta = 1e2
inv = inversion.BaseInversion(invProb, directiveList=[beta, target])
m0 = np.log(np.ones(mtrue.size) * sig_half)
prb.counter = opt.counter = utils.Counter()
opt.remember("xc")
mopt = inv.run(m0)
if plotIt:
fig, ax = plt.subplots(1, 2, figsize=(10, 6))
Dobs = data.dobs.reshape((len(rx.times), len(x)))
Dpred = invProb.dpred.reshape((len(rx.times), len(x)))
for i in range(len(x)):
ax[0].loglog(rx.times - t0, -Dobs[:, i].flatten(), "k")
ax[0].loglog(rx.times - t0, -Dpred[:, i].flatten(), "k.")
if i == 0:
ax[0].legend(("$d^{obs}$", "$d^{pred}$"), fontsize=16)
ax[0].set_xlabel("Time (s)", fontsize=14)
ax[0].set_ylabel("$db_z / dt$ (nT/s)", fontsize=16)
ax[0].set_xlabel("Time (s)", fontsize=14)
ax[0].grid(color="k", alpha=0.5, linestyle="dashed", linewidth=0.5)
plt.semilogx(sigma[active], mesh.vectorCCz[active])
plt.semilogx(np.exp(mopt), mesh.vectorCCz[active])
ax[1].set_ylim(-600, 0)
ax[1].set_xlim(1e-4, 1e-1)
ax[1].set_xlabel("Conductivity (S/m)", fontsize=14)
ax[1].set_ylabel("Depth (m)", fontsize=14)
ax[1].grid(color="k", alpha=0.5, linestyle="dashed", linewidth=0.5)
plt.legend(["$\sigma_{true}$", "$\sigma_{pred}$"])
def halfSpaceProblemAnaDiff(
meshType,
srctype="MagDipole",
sig_half=1e-2,
rxOffset=50.0,
bounds=None,
plotIt=False,
rxType="MagneticFluxDensityz",
):
if bounds is None:
bounds = [1e-5, 1e-3]
if meshType == "CYL":
cs, ncx, ncz, npad = 15.0, 30, 10, 15
hx = [(cs, ncx), (cs, npad, 1.3)]
hz = [(cs, npad, -1.3), (cs, ncz), (cs, npad, 1.3)]
mesh = discretize.CylMesh([hx, 1, hz], "00C")
elif meshType == "TENSOR":
cs, nc, npad = 20.0, 13, 5
hx = [(cs, npad, -1.3), (cs, nc), (cs, npad, 1.3)]
hy = [(cs, npad, -1.3), (cs, nc), (cs, npad, 1.3)]
hz = [(cs, npad, -1.3), (cs, nc), (cs, npad, 1.3)]
mesh = discretize.TensorMesh([hx, hy, hz], "CCC")
active = mesh.vectorCCz < 0.0
actMap = maps.InjectActiveCells(mesh, active, np.log(1e-8), nC=mesh.nCz)
mapping = maps.ExpMap(mesh) * maps.SurjectVertical1D(mesh) * actMap
prb = tdem.Simulation3DMagneticFluxDensity(mesh, sigmaMap=mapping)
prb.Solver = Solver
prb.timeSteps = [(1e-3, 5), (1e-4, 5), (5e-5, 10), (5e-5, 10), (1e-4, 10)]
out = utils.VTEMFun(prb.times, 0.00595, 0.006, 100)
wavefun = interp1d(prb.times, out)
t0 = 0.006
waveform = tdem.Src.RawWaveform(offTime=t0, waveFct=wavefun)
rx = getattr(tdem.Rx,
"Point{}".format(rxType[:-1]))(np.array([[rxOffset, 0.0,
0.0]]),
np.logspace(-4, -3, 31) + t0,
rxType[-1])
if srctype == "MagDipole":
src = tdem.Src.MagDipole([rx],
waveform=waveform,
loc=np.array([0, 0.0, 0.0]))
elif srctype == "CircularLoop":
src = tdem.Src.CircularLoop([rx],
waveform=waveform,
loc=np.array([0.0, 0.0, 0.0]),
radius=13.0)
survey = tdem.Survey([src])
prb.pair(survey)
sigma = np.ones(mesh.nCz) * 1e-8
sigma[active] = sig_half
sigma = np.log(sigma[active])
if srctype == "MagDipole":
bz_ana = mu_0 * analytics.hzAnalyticDipoleT(rx.locations[0][0] + 1e-3,
rx.times - t0, sig_half)
elif srctype == "CircularLoop":
bz_ana = mu_0 * analytics.hzAnalyticCentLoopT(13, rx.times - t0,
sig_half)
bz_calc = prb.dpred(sigma)
ind = np.logical_and(rx.times - t0 > bounds[0], rx.times - t0 < bounds[1])
log10diff = np.linalg.norm(
np.log10(np.abs(bz_calc[ind])) -
np.log10(np.abs(bz_ana[ind]))) / np.linalg.norm(
np.log10(np.abs(bz_ana[ind])))
print(" |bz_ana| = {ana} |bz_num| = {num} |bz_ana-bz_num| = {diff}".format(
ana=np.linalg.norm(bz_ana),
num=np.linalg.norm(bz_calc),
diff=np.linalg.norm(bz_ana - bz_calc),
))
print("Difference: {}".format(log10diff))
if plotIt is True:
plt.loglog(
rx.times[bz_calc > 0] - t0,
bz_calc[bz_calc > 0],
"r",
rx.times[bz_calc < 0] - t0,
-bz_calc[bz_calc < 0],
"r--",
)
plt.loglog(rx.times - t0, abs(bz_ana), "b*")
plt.title("sig_half = {:e}".format(sig_half))
plt.show()
return log10diff