On signal contribution functions and sensitivity for frequency‐domain electromagnetic and direct current electrical resistivity methods.
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| Title: | On signal contribution functions and sensitivity for frequency‐domain electromagnetic and direct current electrical resistivity methods. |
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| Authors: | Butler, S. L.1 (AUTHOR) sam.butler@usask.ca |
| Source: | Geophysical Prospecting. May2025, Vol. 73 Issue 4, p979-993. 15p. |
| Subjects: | Electrical resistivity, Current density (Electromagnetism), Sensitivity analysis, Magnetic fields, Spectrum analysis, Electromagnetic induction |
| Abstract: | Signal contribution functions can be integrated over space to calculate the response of an electrical or electromagnetic technique to a given resistivity distribution. On the other hand, sensitivity functions show how the measured signal changes with a change in resistivity in a region of the ground. Signal contribution functions and sensitivity have been previously presented for the direct current resistivity technique. While useful forms of both the signal contribution function and sensitivity are proportional to the correlation of the current densities from the normal and reciprocal configurations, it has not previously been shown how sensitivity can be derived directly from the signal contribution. For frequency‐domain electromagnetic techniques, there are existing expressions for sensitivity but not for the signal contribution. In this contribution, I show how the direct current signal contribution can be differentiated to obtain the sensitivity. I also derive an expression for the signal contribution function for frequency‐domain electromagnetics and show how it can be differentiated to obtain the sensitivity. The new signal contribution function has a term that, like the sensitivity, is proportional to the electrical current densities from the normal and reciprocal configurations and an additional term that is proportional to the correlation of the magnetic fields from the normal and reciprocal configurations. I show plots of these two terms and investigate their magnitudes as a function of the induction number. This new expression will be useful for testing numerical models and aids in understanding the measured results in frequency‐domain electromagnetics. [ABSTRACT FROM AUTHOR] |
| Copyright of Geophysical Prospecting is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 185839403 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: On signal contribution functions and sensitivity for frequency‐domain electromagnetic and direct current electrical resistivity methods. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Butler%2C+S%2E+L%2E%22">Butler, S. L.</searchLink><relatesTo>1</relatesTo> (AUTHOR)<i> sam.butler@usask.ca</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Geophysical+Prospecting%22">Geophysical Prospecting</searchLink>. May2025, Vol. 73 Issue 4, p979-993. 15p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Electrical+resistivity%22">Electrical resistivity</searchLink><br /><searchLink fieldCode="DE" term="%22Current+density+%28Electromagnetism%29%22">Current density (Electromagnetism)</searchLink><br /><searchLink fieldCode="DE" term="%22Sensitivity+analysis%22">Sensitivity analysis</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+fields%22">Magnetic fields</searchLink><br /><searchLink fieldCode="DE" term="%22Spectrum+analysis%22">Spectrum analysis</searchLink><br /><searchLink fieldCode="DE" term="%22Electromagnetic+induction%22">Electromagnetic induction</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Signal contribution functions can be integrated over space to calculate the response of an electrical or electromagnetic technique to a given resistivity distribution. On the other hand, sensitivity functions show how the measured signal changes with a change in resistivity in a region of the ground. Signal contribution functions and sensitivity have been previously presented for the direct current resistivity technique. While useful forms of both the signal contribution function and sensitivity are proportional to the correlation of the current densities from the normal and reciprocal configurations, it has not previously been shown how sensitivity can be derived directly from the signal contribution. For frequency‐domain electromagnetic techniques, there are existing expressions for sensitivity but not for the signal contribution. In this contribution, I show how the direct current signal contribution can be differentiated to obtain the sensitivity. I also derive an expression for the signal contribution function for frequency‐domain electromagnetics and show how it can be differentiated to obtain the sensitivity. The new signal contribution function has a term that, like the sensitivity, is proportional to the electrical current densities from the normal and reciprocal configurations and an additional term that is proportional to the correlation of the magnetic fields from the normal and reciprocal configurations. I show plots of these two terms and investigate their magnitudes as a function of the induction number. This new expression will be useful for testing numerical models and aids in understanding the measured results in frequency‐domain electromagnetics. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Geophysical Prospecting is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1111/1365-2478.70011 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 15 StartPage: 979 Subjects: – SubjectFull: Electrical resistivity Type: general – SubjectFull: Current density (Electromagnetism) Type: general – SubjectFull: Sensitivity analysis Type: general – SubjectFull: Magnetic fields Type: general – SubjectFull: Spectrum analysis Type: general – SubjectFull: Electromagnetic induction Type: general Titles: – TitleFull: On signal contribution functions and sensitivity for frequency‐domain electromagnetic and direct current electrical resistivity methods. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Butler, S. L. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 05 Text: May2025 Type: published Y: 2025 Identifiers: – Type: issn-print Value: 00168025 Numbering: – Type: volume Value: 73 – Type: issue Value: 4 Titles: – TitleFull: Geophysical Prospecting Type: main |
| ResultId | 1 |
