E4D User Guide
E4D User Guide
Travel-time Methods Survey File
The input survey file provides the locations of sensors and describes how sensors are used to produce measurements.
In inverse run modes, the input survey file also lists measurement values and standard deviations.
An output survey file with the extension of <.srv> is created during Forward Modeling
that is named after the conductivity file used in the forward simulation. The simulated measurements are entered in place of the observed measurements.
This file is meant to aid synthetic imaging studies, whereby simulated data collected within a known conductivity distribution are used to investigate aspects
of the inversion. The standard deviation of each measurement is entered as 5% of the travel time magnitude as a placeholder,
but noise is not added to the simulated data.
See File Syntax Rules for specific details.
Variable Name | Description |
---|---|
n_sens
(int) |
n_sens is the number of sensors. |
e_ind ex ey ez e_flag
(int) (real) (real) (real) (int) |
repeat for n_sens e_ind is the sensor number. ex, ey and ez are the coordinate positions of the sensor. e_flag is the boundary flag for the sensor. e_flag = 0sensor is below the surface e_flag = 1sensor is on the surface |
n_meas
(int) |
n_sens is the number of measurements. |
m_ind a b v_obs v_std
(int) (int) (int) (real) (real) |
repeat for n_meas m_ind is the measurement number. a is the sensor index of the source sensor. b is the sensor index of the receiver sensor. v_obs is the observed travel-time*. v_std is the standard deviation of v_obs*. *For forward modeling, v_obs and v_std are not used, however a value must be entered. |
Forward TT Simulation Modeling Example
16 number of sensors 1 -7.5 0 -6 1 e_ind, x, y, z, borehole sensor values for sensor 1 2 -7.5 0 -10 1 e_ind, x, y, z, borehole sensor values for sensor 2 3 -7.5 0 -14 1 e_ind, x, y, z, ... 64 number of measurements 1 1 10 10.0 1.0 m_ind a b v_obs v_std 2 1 11 10.0 1.0 note: the v_obs and v_std are arbitrary placeholders in this example ...
Forward TT Modeling Output Example
16 number of sensors 1 -7.5 0 -6 1 e_ind, x, y, z, borehole sensor values for sensor 1 2 -7.5 0 -10 1 e_ind, x, y, z, borehole sensor values for sensor 2 3 -7.5 0 -14 1 e_ind, x, y, z, ... 64 number of measurements 1 1 9 16.054 0.8127 m_ind a b v_obs v_std 2 1 10 16.603 0.84013 note: simulated measurement values, v_std=0.05*|v_obs| 3 1 11 18.692 0.94459 ...
Inverse TT Modeling Input Example
16 number of sensors 1 -7.5 0 -6 1 e_ind, x, y, z, borehole sensor values for sensor 1 2 -7.5 0 -10 1 e_ind, x, y, z, borehole sensor values for sensor 2 3 -7.5 0 -14 1 e_ind, x, y, z, ... 64 number of measurements 1 1 9 16.054 0.32108 m_ind a b v_obs v_std 2 1 10 16.603 0.33206 note: v_std is determined from field data errors, in this case 0.02*|v_obs| 3 1 11 18.692 0.37384 ...