Back-propagation network calculating method of apparent resistivity

Abstract

The invention relates to a back-propagation network calculating method of apparent resistivity, which is especially suitable for calculating the apparent resistivity under the condition of a transientelectromagnetic detecting center return-wire device and belongs to the field of geophysical exploration and engineering geological exploration. The back-propagation network calculating method of theapparent resistivity comprises the following steps: defining a kernel function of an expression of a secondary magnetic field of the transient electromagnetic detecting center return-wire device, which is changed following time, and establishing a solving function of the apparent resistivity; selecting a sample training function and a reverse training method taking a kernel function value as inputand a transient parameter as output; carrying out initial calculation through measuring values; and guiding calculating results into different network structures according to different measuring characteristics. The back-propagation network calculating method replaces a numerical value method with a trained back-propagation network for calculation, thereby simplifying the calculating process andbeing easy to realize the programming; and in addition, with the parallel structure processing characteristics of a neural network, the calculating time is greatly shortened.

Description

technical field [0001] The present invention relates to the calculation method of apparent resistivity by transient electromagnetic method, which is especially suitable for calculating apparent resistivity under the condition of transient electromagnetic detection center loop device, and is suitable as the inverse problem of solving apparent resistivity by secondary response field by transient electromagnetic method . Background technique [0002] In the field of transient electromagnetic detection, it is necessary to collect the response signal from the transient secondary field by the receiving device, and obtain different apparent resistivities containing geological information through post-processing of the response signal. Apparent resistivity is a parameter used in electrical prospecting to reflect changes in the electrical conductivity of the measurement target, represented by the symbol ρ. In the transient electromagnetic method, the apparent resistivity is equal to...

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Problems solved by technology

[0004] In the numerical calculation method, the process of the early and late calculation methods is: based on the response time t in the response expression of the central loop line, the expression is simplified into two cases from t→0 and t→∞ to calculate. The disadvantage of the method is that the calculated apparent resistivity value has no definition or large error in the early transient stage when fitting the full-range apparent resistivity; iterative calculation using step response, the calculation process is to select an initial iterative value and calculate For the transient response value, the calculation result is compared with the known received data to adjust the initial value to be close to the exact value. The disadvantage of this method is that the calculation process depends on the selection of the initial value, which makes the calculation process unstable and the calculation speed is limited. limit

This method still has the problem of time-consuming calculation. The apparent resistivity result cannot be obtained from the received data in real time. The apparent resistivity asymptotic formula can directly obtain the calculation result, but the calculation accuracy is not enough, and the apparent resistivity cannot be obtained from the received data in time. rate results for on-site analysis

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