Journal articles: 'Electrical resistivity modelling'

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Ahmed Hassan, Asem. "Performance of Various Electrical Resistivity Configurations for Detecting Buried Tunnels Using 2D Electrical Resistivity Tomography Modelling." DJES 11, no. 3 (September 1, 2018): 14–21. http://dx.doi.org/10.24237/djes.2018.11303.

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This work aims to evaluate performance of 2D electrical resistivity modelling technique for detecting buried tunnels using various electrode configurations. A synthetic resistivity model was designed to explore the capability of Wenner, Wenner- Schlumberger, Dipole-Dipole, Pole-Dipole and Pole-Pole electrode configurations for detecting buried tunnels at different noise levels. 2D forward modelling (RES2DMOD) and 2D inversion (RES2DINV) software were implemented using blocky L1 norm optimization method. The results showed that the modelled tunnel can clearly be detected at 0% noise level due to the high resistivity contrast between the synthetic tunnel and the surrounding host materials. At 0-30% noise levels, the results indicated that dipole-dipole and Wenner- Schlumberger in the second order perform better than other configurations. This can be attributed to the characteristics features and sensitivity of these configurations for resolving the subsurface resistivity changes. It is suggested that these configurations are more suitable for detecting the buried structures. The results also showed that the inversion artifacts caused by high noise levels may smear the resistivity signature of the burred targets for particular configurations. Thus, obtaining high quality data ensures reliable resistivity interpretations. The study demonstrated the usefulness of the 2D numerical modelling for planning of electrical resistivity surveys.

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Kasi, Harsha, Robert Meissner, Alexandre Babalian, Harald van Lintel, Arnaud Bertsch, and Philippe Renaud. "Direct localised measurement of electrical resistivity profile in rat and embryonic chick retinas using a microprobe." Journal of Electrical Bioimpedance 1, no. 1 (July 23, 2019): 84–92. http://dx.doi.org/10.5617/jeb.149.

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Abstract We report an alternative technique to perform a direct and local measurement of electrical resistivities in a layered retinal tissue. Information on resistivity changes along the depth in a retina is important for modelling retinal stimulation by retinal prostheses. Existing techniques for resistivity-depth profiling have the drawbacks of a complicated experimental setup, a less localised resistivity probing and/or lower stability for measurements. We employed a flexible microprobe to measure local resistivity with bipolar impedance spectroscopy at various depths in isolated rat and chick embryo retinas for the first time. Small electrode spacing permitted high resolution measurements and the probe flexibility contributed to stable resistivity profiling. The resistivity was directly calculated based on the resistive part of the impedance measured with the Peak Resistance Frequency (PRF) methodology. The resistivity-depth profiles for both rat and chick embryo models are in accordance with previous mammalian and avian studies in literature. We demonstrate that the measured resistivity at each depth has its own PRF signature. Resistivity profiles obtained with our setup provide the basis for the construction of an electric model of the retina. This model can be used to predict variations in parameters related to retinal stimulation and especially in the design and optimisation of efficient retinal implants.

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Putiška, René, Maroš Nikolaj, Ivan Dostál, and David Kušnirák. "Determination of cavities using electrical resistivity tomography." Contributions to Geophysics and Geodesy 42, no. 2 (January 1, 2012): 201–11. http://dx.doi.org/10.2478/v10126-012-0018-3.

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Abstract Geophysical surveys for cavity detection are one of the most common nearsurface applications. The usage of resistivity methods is also very straightforward for the air-filled underground voids, which should have theoretically infinite resistivity in the ERT image. In the first part of the paper, we deal with the comparison of detectability of the cavity by several types of the electrode arrays, the second part discusses the effect of a thin layer around the cavity itself, by means of 2D modelling. The presence of this layer deforms the resistivity image significantly as the resistive anomaly could be turned into a conductive one, in the case when the thin layer is more conductive than the background environment. From the electrical array analysis for the model situation a dipole-dipole and combined pole-dipole shows the best results among the other involved electrical arrays.

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Thapa, Dilli Ram. "Use of two dimensional electrical resistivity tomography (2D- ERT) synthetic modelling to detect collapse masses." Journal of Nepal Geological Society 60 (September 16, 2020): 139–45. http://dx.doi.org/10.3126/jngs.v60i0.31250.

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The presence of collapse masses in the subsurface causes severe problems in the geotechnical design activities. In this study, two dimensional Electrical Resistivity Tomography (2D-ERT) synthetic modelling techniques were used to detect collapse masses commonly found in the river bank. Two dimensional (2D) resistivity models are first created utilizing prior information of collapsed masses in the river bank and afterward inverted to reconstruct the resistivity distribution in the subsurface. The resulting two dimensional models exhibits that collapsed masses can be better detected particularly at low resistivity noise level (2%) than the high noise levels (5% and 10%). The models are particularly very useful prior to executing the field investigations in the river bank sites and furnish the subsurface geology as well as the successful interpretation of the results withconfidence.

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Lavoué, F., J. van der Krak, J. Rings, F. André, D. Moghadas, J. A. Huisman, S. Lambot, L. Weiherrnüller, J. Vanderborght, and H. Vereecken. "Electromagnetic induction calibration using apparent electrical conductivity modelling based on electrical resistivity tomography." Near Surface Geophysics 8, no. 6 (July 1, 2010): 553–61. http://dx.doi.org/10.3997/1873-0604.2010037.

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Ramli, Nadia, Hamzah Hussin, Muhammad Afiq Abdul Kahar, and Mohd Amir Asyraf Sulaiman. "The Utilisation of Electrical Resistivity Imaging (ERI) for Geological Structures Mapping in Rock Mass: A Review." IOP Conference Series: Earth and Environmental Science 1102, no. 1 (November 1, 2022): 012089. http://dx.doi.org/10.1088/1755-1315/1102/1/012089.

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Electrical Resistivity Imaging (ERI) is an in-situ geophysical method widely used in environmental, engineering and hydrogeological explorations due to cost, time, and data coverage efficiency. Traditionally, geotechnical parameters such as discontinuities properties are obtained from rock samples acquired from a borehole. However, it only provides a single information point, costly and time-consuming. Thus, an approach using electrical resistivity to detect the presence of geological structure in a rock mass is an alternative method that can be applied. Discontinuities in rock mass include joints, bedding planes, blasting cracks, fractures, faults, and folds. This paper aims to present the utilisation of geoelectrical resistivity imaging for geological structures mapping in rock mass based on the review from previous research. The Electrical Resistivity Imaging (ERI) method is an effective tool to obtain structural differentiation of geological medium by interpreting 2D and even 3D electrical resistivity models. Electrical Resistivity Imaging (ERI) is an automated data acquisition system, inversion codes, non-invasive and user-friendly. The raw data received from data acquisition was analysed using Res2DINV software. The data inversion was done by applying the robust method and finite element grid to accommodate the steep topography. The data interpretation included numerical modelling to assess the suitability of all used electrode arrays in relation to the geological setting.

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Ahmed Hassan, Asem. "Numerical Modelling of Subsurface Cavities Using 2D Electrical Resistivity Tomography Technique." Diyala Journal For Pure Science 13, no. 2 (April 1, 2017): 197–216. http://dx.doi.org/10.24237/djps.1302.260a.

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Hazreek, Z. A. M., Z. M. Nizam, A. T. S. Azhar, M. Aziman, and M. Z. N. Shaylinda. "Physical Modelling on Detecting Buried Object Using Electrical Resistivity Imaging (ERI)." IOP Conference Series: Materials Science and Engineering 136 (July 2016): 012008. http://dx.doi.org/10.1088/1757-899x/136/1/012008.

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Cardarelli, E., and F. Fischanger. "2D data modelling by electrical resistivity tomography for complex subsurface geology." Geophysical Prospecting 54, no. 2 (March 2006): 121–33. http://dx.doi.org/10.1111/j.1365-2478.2006.00522.x.

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Cadeville, M. C., V. Pierron-Bohnes, J. M. Sanchez, and J. M. Sanchez. "Modelling of the electrical resistivity of ferromagnetic and paramagnetic intermetallic compounds." Journal of Physics: Condensed Matter 4, no. 46 (November 16, 1992): 9053–66. http://dx.doi.org/10.1088/0953-8984/4/46/013.

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Vyzhva, S., V. Onyshchuk, I. Onyshchuk, M. Reva, and O. Shabatura. "ELECTRICAL PARAMETERS OF THE UPPER CARBON ROCKS (RUNOVSHCHYNSKA AREA OF THE DNIEPER-DONETSK BASIN)." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 2 (85) (2019): 37–45. http://dx.doi.org/10.17721/1728-2713.85.05.

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The main objective of this article is to study electrical parameters of sandstones and argillites of the Upper Carbon rocks in the Runovshchynska area of the Dnieper-Donets basin. It has been determined that specific electrical resistivity of dry rock samples (specific electrical resistivity of rock matrix) varies from 44,802 kΩ·m to 6,115 МΩ·m (average 751,328 kΩ·m). Specific electrical resistivity of sandstones is 3,45 times more than argillitesdue to different shaliness of studied rocks. Specific electrical resistivity of saturated rocks samples varies from 0,54 Ω·m to 10,46 Ω·m (average 1,23 Ω·m). Specific electrical resistivity of argillites is 2,46 times more than sandstones because the latter had high content of reservoir water in their pores (sandstones had better conductivity). It has been determined that formation resistivity factor of sandstones in atmospheric conditions varies from 6,05 to 33,71 (argillites 11,8), and argillites – from 4,76 to 51,47 (average 17,4). Physical modelling of reservoir conditions (temperature t = 78,5°С, pressure p = 31–31,9 MPa, mineralization M= 170 g/l) showed that specific electrical resistivity varies from 0,3 Ω·m to 3,0 Ω·m (average 0,75 Ω·m). Sandstones in reservoir conditions had the range from 0,3 Ω·m to 2,3 Ω·m (average 0,7 Ω·m), and argillites – from 0,5 Ω·m to 3,0 Ω·m (average 1,2 Ω·m). In this case, specific electrical resistivity of argillites is 1,6 times more than sandstones. Due to the closure of microcracks and the deformation of the pore space, the electrical resistance of rocks increases with increasing pressure. The dependence of formation resistivity enlargement factor on pressure for the studied rocks is expressed by 2-order polynomials. The formation resistivity factor of the studied rocks in reservoir conditions has been determined. It was defined that sandstones in reservoir conditions had the range of the formation resistivity factor from 5,4 to 63,3 (average 20,3), and porosity coefficient – from 0,038 to 0,175 (average 0,113). The range of the formation resistivity factor for argillites was from 13,4 to 88,7 (average 34,3), and porosity coefficient – from 0,043 to 0,115 (average 0,086). Analysis of data of laboratory electrometric investigations has allowed establishing correlations between the porosity coefficient and formation resistivity factor. In addition, the correlation of electrical parameters of rocks in atmospheric and reservoir conditions and the formation resistivity enlargement factor from the water saturation coefficient, taking into account the lithological varieties of the studied rocks, was established.

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Hassan, Noha A., Mohamed H. Khalil, and Mahmoud Ghaleb. "Magnetic and Geo-electrical Geophysical Techniques for Subsurface Delineation and Groundwater Assessment in Ras Matarma, Sinai." Journal of Environmental and Engineering Geophysics 25, no. 3 (September 2020): 425–31. http://dx.doi.org/10.32389/jeeg20-007.

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Groundwater constitutes the main source of the freshwater in Ras-Matarma, Sinai, which necessitates optimized management of it. In this context, geophysical ground magnetic, Schlumberger resistivity inversion, remote sensing (RS), geographic information system (GIS), and pumping tests were conducted. The magnetic survey comprised 56 profiles, whereas, Schlumberger resistivity survey were 27 VES. GIS and RS were implemented for watershed analyses in the area. Interpretation of the magnetic data separated significantly the shallow and deep structures with depths ranged from 300 to 1400 m. Qualitative and quantitative modelling of the inverted resistivity data demarcated effectively the fresh aquifer with true resistivity and thickness ranged from 22 to 210 ohm.m and 2 to 80 m, respectively. GIS aggregated all the aforementioned results along with electric and hydraulic parameters of the fresh aquifer.

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Vu, M. T., A. Jardani, A. Revil, and M. Jessop. "Magnetometric resistivity tomography using chaos polynomial expansion." Geophysical Journal International 221, no. 3 (February 14, 2020): 1469–83. http://dx.doi.org/10.1093/gji/ggaa082.

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SUMMARY We present an inversion algorithm to reconstruct the spatial distribution of the electrical conductivity from the analysis of magnetometric resistivity (MMR) data acquired at the ground surface. We first review the theoretical background of MMR connecting the generation of a magnetic field in response to the injection of a low-frequency current source and sink in the ground given a known distribution of electrical conductivity in the subsurface of the Earth. The forward modelling is based on sequentially solving the Poisson equation for the electrical potential distribution and the magnetostatic (Biot and Savart) equation for the magnetic field. Then, we introduce a Gauss–Newton inversion algorithm in which the logarithm of the electrical conductivity field is parametrized by using the chaos polynomial expansion in order to reduce the number of model parameters. To illustrate how the method works, the algorithm is successfully applied on four synthetic models with 3-D heterogeneous distribution of the electrical conductivity. Finally, we apply our algorithm to a field case study in which seepage was known to be occurring along an embankment of a headrace channel to a power station.

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Abdi, Sifeddine, Abderrahmane Manu Haddad, Noureddine Harid, and Ahmed Boubakeur. "Modelling the Effect of Thermal Aging on Transformer Oil Electrical Characteristics Using a Regression Approach." Energies 16, no. 1 (December 29, 2022): 381. http://dx.doi.org/10.3390/en16010381.

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The effect of thermal aging on the electrical properties of the insulating oil used for transformers has been explored in this experimental work. In particular the dielectric dissipation factor, the resistivity and the breakdown voltage have been measured and correlated. The numerical results predicted by mathematical model and those measured in the laboratory have been compared by using a regression analysis. Experiments on thermal aging were performed on insulating oil (Borak 22, Nynas, Austria) during a period of time of 5000-h at three different temperatures. First, the transformer oil’s dielectric dissipation factor, the resistivity and the breakdown voltage are measured after every 500 h of aging. Then, polynomial and exponential regression expressions are proposed for modelling the oil’s electrical parameters variations with thermal ageing at different aging temperatures and periods. The results show that after thermal aging, the resistivity and the breakdown voltage decrease with thermal aging, however, the dielectric dissipation factor which increases. This trend is similar for all different aging temperatures. The numerical results show close agreement with the measured results for all the samples and all studied properties. The regression model presents strong correlation with high coefficients (>94%).

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Kneisel, C., A. Bast, and D. Schwindt. "Quasi-3-D resistivity imaging – mapping of heterogeneous frozen ground conditions using electrical resistivity tomography." Cryosphere Discussions 3, no. 3 (October 30, 2009): 895–918. http://dx.doi.org/10.5194/tcd-3-895-2009.

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Abstract. Up to now an efficient 3-D geophysical mapping of the subsurface in mountainous environments with rough terrain has not been possible. A merging approach of several closely spaced 2-D electrical resistivity tomography (ERT) surveys to build up a quasi-3-D model of the electrical resistivity is presented herein as a practical compromise for inferring subsurface characteristics and lithology. The ERT measurements were realised in a small glacier forefield in the Swiss Alps with complex terrain exhibiting a small scale spatial variability of surface substrate. To build up the grid for the quasi-3-D measurements the ERT surveys were arranged as parallel profiles and perpendicular tie lines. The measured 2-D datasets were collated into one quasi-3-D file. A forward modelling approach – based on studies at a permafrost site below timberline – was used to optimize the geophysical survey design for the mapping of the mountain permafrost distribution in the investigated glacier forefield. Quasi-3-D geoelectrical imaging is a useful method for mapping of heterogeneous frozen ground conditions and can be considered as a further milestone in the application of near surface geophysics in mountain permafrost environments.

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Yusoh, Rais, Md Azlin Md Said, Mohd Ashraf Mohamad Ismail, and Mohd Firdaus Abdul Razak. "Subsurface Characterization Using Ground and Underwater Resistivity Techniques for Groundwater Abstraction." Applied Mechanics and Materials 802 (October 2015): 629–33. http://dx.doi.org/10.4028/www.scientific.net/amm.802.629.

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A geophysical method was used in studying the subsurface profile for investigating the aquifer existence at Jenderam Hilir, Selangor, Malaysia. The 2-D electrical resistivity technique is to determine the presence of aquifer suitable for groundwater abstraction. Resistivity was measured through an ABEM SAS 4000 Terrameter and ABEM Terrameter LS. 2-D electrical-imaging resistivity data of subsurface profile for each survey line were calculated inverse modelling, validate by borehole data which showed the lithology: sandy clay to sandy silt sediments more than 3 m deep, composed of alternating layers of silty and sand. The aquifer potential are mostly in silty sand zones which resistivity value should be within 60-800 ohm-m. Based on interpretation, a potential water-bearing aquifer was located at a depth of 3 m and below which is good agreement with interpreted results. 2-D underwater resistivity survey lines were conducted across the ground and river. Resistivity image was interpreted as silty sand under the river bed, which the subsurface aquifer on land has a physical contact with surface water. Result has shown that ground and underwater resistivity technique can be used as alternative method in finding a good location for groundwater abstraction.

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SOUZA, HERCULES DE, and EDSON E. S. SAMPAIO. "Apparent resistivity and spectral induced polarization in the submarine environment." Anais da Academia Brasileira de Ciências 73, no. 3 (September 2001): 429–44. http://dx.doi.org/10.1590/s0001-37652001000300011.

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Relatively few investigations have employed electrical methods in the submarine environment, which may be promising for mineral deposits or threatened by environmental problems. We have measured the electric field using both disk and bar electrodes in the sea water at three different levels: sea surface, seven meters deep, and sea bottom at a depth of ten meters, employing a 2 m spacing dipole-dipole array with 7 array spacings of investigation, and 13 values of frequencies at steps of (2N hertz, N = -2, -1, 0, 1, 2,.....10). The measurement allowed the analysis of the electric field as a function of frequency and spacing, and of the spectral induced polarization. Modelling and interpretation of the apparent resistivity yielded a good fit with previous drilling data. Analysis of the spectrum of the complex apparent resistivity and the comparison with equivalent circuits, provided information about the grain size, the mineral composition and the major induced polarization phenomenon occurring below the sea. Therefore the result of the present research show the feasibility of measuring the variation of seawater resistivity in situ, as well as the resistivity of sea bottom sediments.

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Banu, Asfana, and Mohammad Yeakub Ali. "Electrical Discharge Machining (EDM): A Review." International Journal of Engineering Materials and Manufacture 1, no. 1 (September 3, 2016): 3–10. http://dx.doi.org/10.26776/ijemm.01.01.2016.02.

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Electro discharge machining (EDM) process is a non-conventional and non-contact machining operation which is used in industry for high precision products. EDM is known for machining hard and brittle conductivematerials since it can melt any electrically conductive material regardless of its hardness. The workpiece machined by EDM depends on thermal conductivity, electrical resistivity, and melting points of the materials. The tool and the workpiece are adequately both immersed in a dielectric medium, such as, kerosene, deionised water or any other suitable fluid. This paper is reviewed comprehensively on types of EDM operation. A brief discussion is also done on the machining responses and mathematical modelling.

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Enebeli, V. C., C. N. Okorafor, and R. E. Kolagbodi. "2-D Electrical Resistivity Imaging Survey for Lithological Assessment at Igwete Primary School, Amai, South-South Nigeria." Journal of Applied Sciences and Environmental Management 25, no. 5 (October 28, 2021): 823–27. http://dx.doi.org/10.4314/jasem.v25i5.21.

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Electrical Resistivity Imaging (ERI) is a useful near-surface imaging technique, which mainly include data acquisition, numerical modelling and tomographic inversion. Within the study area, only one – dimensional (1-D) Electrical Resistivity survey has been carried out for Geophysical investigations. Therefore, 2-D ERI survey was carried out at the Igwete Primary School, Amai to provide electrical picture of the subsurface from which discrete bodies and lithology are better revealed vertically and in lateral extent. The 2-D ERT survey data were acquired using the Petrozenith Earth Resistivity meter while employing the Wenner electrode array. The 2-D apparent resistivity data were inverted to obtain true resistivities of the subsurface using res2dinv software running on personal computer. The subsurface resistivity models were displayed as pseudo sections and inverted resistivity section in the form of colour shaded contour maps. The inverse resistivity model images indicate that at a lateral extent in the range (15.00-21.00) m and (33.00-39.00) m, anomalies suspected to be gravel mixed with sand is in place with resistivities of about (254.00-948.00) Ωm. From the geologic section we can infer that a geological formation is observed at a lateral position of (27.00-32.00) m of resistivity in the range (90.00-93.00) Ωm. This structure is inferred to be a clay pocket. The sandy nature of the formation requires that underground water development be sought for at (9.00-15.00) m over a depth (2.30-8.00) m in the sandy environment. Results of 2D resistivity imaging has helped to delineate the lithology which comprise mainly of; sand, sandy clay, clayey sand depositional environment. The resistivity of these lithology falls in the range (90.00-93.00) Ωm with depth to formation of about (2.30-6.00) m.

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Xiang, Nan, Yu Wang, Hayder M. Oleiwi, Edmund Chadwick, Guowen Yao, Levingshan Augusthus-Nelson, Xianyi Chen, and Igor Shabalin. "Modelling the electrical resistivity of concrete with varied water and chloride contents." Magazine of Concrete Research 72, no. 11 (June 2020): 552–63. http://dx.doi.org/10.1680/jmacr.18.00198.

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Piegari, E., V. Cataudella, R. Di Maio, L. Milano, M. Nicodemi, and M. G. Soldovieri. "Electrical resistivity tomography and statistical analysis in landslide modelling: A conceptual approach." Journal of Applied Geophysics 68, no. 2 (June 2009): 151–58. http://dx.doi.org/10.1016/j.jappgeo.2008.10.014.

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Keeling, D. L., C. D. Challis, I. Jenkins, N. C. Hawkes, I. Lupelli, C. Michael, and M. F. M. de Bock. "Test of electrical resistivity and current diffusion modelling on MAST and JET." Nuclear Fusion 58, no. 1 (November 16, 2017): 016028. http://dx.doi.org/10.1088/1741-4326/aa9495.

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Mita, Magdalena, Michał Glazer, Radosław Kaczmarzyk, Michał Dąbrowski, and Karolina Mita. "Case study of electrical resistivity tomography measurements used in landslides investigation, Southern Poland." Contemporary Trends in Geoscience 7, no. 1 (June 1, 2018): 110–26. http://dx.doi.org/10.2478/ctg-2018-0007.

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AbstractMass movements are an ever present threat to building construction, water management, vegetation formation and biodiversity. This paper presents an approach to landslides research based on non-invasive geoelectrical method - Electrical Resistivity Tomography (ERT). Mapping and displacement monitoring of unstable slopes is crucial for the hazards prevention and assessment. The ERT technique is an effective tool to obtain structural differentiation of geological medium through interpretation of 2D electrical resistivity models. The main advantage of the method is a wide range of applicability what makes its useful during field works on a landslide. It is commonly used for measurements of slope instability, determination of shear surface, landslide susceptibility, depth of bedrock, slip plane geometry. The aim of the work is to identify the geological structures underneath three selected landslides in south Poland: in Racibórz, Milówka and Porąbka. Attempts have been focused on determination of the usefulness of the proposed ERT methodology for evaluation of possible further development of mass movements. On two investigation sites two different arrays have been used: Wenner-Schlumberger and dipole-dipole which allowed to prepare combined data set and resistivity models based on them. Forward modelling of synthetic models based on a priori information allowed to understand anomalies present on resistivity models. Applied approach ensured quality increase of final interpretation of resistivity models.

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Li, He, Zhipeng Qi, Xiu Li, and Yingying Zhang. "Numerical modelling analysis of multi-source semi-airborne TEM systems using a TFEM." Journal of Geophysics and Engineering 17, no. 3 (February 26, 2020): 399–410. http://dx.doi.org/10.1093/jge/gxz119.

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Abstract Traditional transient electromagnetic methods use single sources for excitation and extract the characteristics of underground media by improving interpretation technology. This study focused the improvements of transient electromagnetic interpretation using complex source technology. A time-domain vector finite element method (TFEM) was applied on three-dimensional forward modelling of semi-airborne transient electromagnetic (TEM) with multiple electrical sources, and it analysed the characteristics of fields with multiple sources. The study used a model of an isolated anomalous body in a homogeneous medium as an example. The effects of different combinations of excitation sources on the distributions of the magnetic field characteristics were analysed. Numerical results showed that the magnetic field components in a specific area could be strengthened by changing the layout of the sources, which was significant for future field data collections. By comparing the transient electromagnetic fields of the vertical array dipole sources with that of the loop source, the anomaly transient electromagnetic field of multi-source was more obvious than the field with a single source. Taking a complex orebody model as an example, a cross-electric source was used to calculate the magnetic field components of the semi-airborne TEM method. The resistivity distribution characteristics of the underground medium were obtained using an apparent resistivity interpretation method of the vertical magnetic field, which fully demonstrated that a multi-source transient electromagnetic system had the ability to determine abundant resistivity information of a complex medium.

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Merritt, A. J., J. E. Chambers, P. B. Wilkinson, L. J. West, W. Murphy, D. Gunn, and S. Uhlemann. "Measurement and modelling of moisture—electrical resistivity relationship of fine-grained unsaturated soils and electrical anisotropy." Journal of Applied Geophysics 124 (January 2016): 155–65. http://dx.doi.org/10.1016/j.jappgeo.2015.11.005.

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Dostál, Ivan, René Putiška, and David Kušnirák. "Determination of shear surface of landslides using electrical resistivity tomography." Contributions to Geophysics and Geodesy 44, no. 2 (June 1, 2014): 133–47. http://dx.doi.org/10.2478/congeo-2014-0008.

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Abstract Geophysical methods offer a broad spectrum of information by dealing with slope deformations. The electrical resistivity tomography (ERT) method is mainly applied for spatial localization of the landslide body and depicting the shear zone position. This article presents the application of the ERT method for the landslide hazardous areas by means of numerical modelling. Four different synthetic models with very small resistivity contrast (30 Ohm.m/50 Ohm.m), where each model represents a different type of slope deformation, were tested by several factors affecting the final inverse model: measurement point density, L1 and L2 norm and L-norm roughness filter components. The higher measurement points density helps mainly to detect the boundaries at greater depths. Inverse models computed using the L1 norm bring satisfactory results for compact anomalous bodies, i.e. water saturated landslide body. In the case of subtle conductive zones, i.e. shear planes, the L2 norm based inversion is recommended. For enhanced reconstruction of skewed anomalous objects, roughness filter including a diagonal component produces more accurate inverse image. The article also demonstrates the ability of the ERT method to detect and describe the shape of the slope deformation even by a relative subtle resistivity contrast

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Man, H. N., and X. D. Jing. "Network modelling of strong and intermediate wettability on electrical resistivity and capillary pressure." Advances in Water Resources 24, no. 3-4 (February 2001): 345–63. http://dx.doi.org/10.1016/s0309-1708(00)00061-0.

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Man, H. N., and X. D. Jing. "Network modelling of mixed-wettability on electrical resistivity, capillary pressure and wettability indices." Journal of Petroleum Science and Engineering 33, no. 1-3 (April 2002): 101–22. http://dx.doi.org/10.1016/s0920-4105(01)00179-6.

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Tso, Chak-Hau Michael, Oliver Kuras, Paul B. Wilkinson, Sebastian Uhlemann, Jonathan E. Chambers, Philip I. Meldrum, James Graham, Emma F. Sherlock, and Andrew Binley. "Improved characterisation and modelling of measurement errors in electrical resistivity tomography (ERT) surveys." Journal of Applied Geophysics 146 (November 2017): 103–19. http://dx.doi.org/10.1016/j.jappgeo.2017.09.009.

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Eluwole, Akinola B., Olusola A. OlaOlorun, Oladimeji L. Ademilua, Abel O. Talabi, Adeyinka O. Aturamu, Yemisi C. Ajisafe, Olufemi F. Ojo, and Christopher A. Ajayi. "Subsurface electrical resistivity modelling over a suspected fault zone at Ojirami, Southwestern Nigeria." Modeling Earth Systems and Environment 6, no. 4 (June 24, 2020): 2543–51. http://dx.doi.org/10.1007/s40808-020-00848-0.

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Situmorang, H., N. Nurhasan, R. Rusdiana, S. Viridi, and D. Fitriani. "Subsurface Structure Analysis of Landslide Potential Areas Based on Electrical and Physical Properties of Soil." Journal of Physics: Conference Series 2377, no. 1 (November 1, 2022): 012044. http://dx.doi.org/10.1088/1742-6596/2377/1/012044.

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Indonesia is a tropical region with a high level of rainfall in November-December for the 2020-2021 period, especially in the West Java region. Jayagiri is one of the villages in Lembang district, West Bandung regency, which experienced landslides due to heavy rainfall. High and constant rainfall causes the soil layer to become saturated and unable to withstand the water, so soil movement occurs. Identification of landslide slip field identification can be analyzed by the geoelectric method and some soil samples for laboratory tests. Four lines of DC resistivity surveys were carried out in the research area using a multichannel instrument. The result of two-dimensional modelling resistivity shows a wide zone of saturation online JG-1 to a depth of around 10 m. Based on the laboratory soil test, permeable soil with a high porosity dominated the area. Low resistivity variation values ranging from 3.79 - 93 Ωm correspond to the low saturation zones. The constituent rocks of the saturation zone are clay, loam, and sand.

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Vyzhva, S., V. Onyshchuk, M. Orlyuk, I. Onyshchuk, M. Reva, and O. Shabatura. "ELECTRIC AND ELASTIC PARAMETERS OF CARBONIC PERIOD TERRIGENOUS ROCKS OF THE EASTERN PART OF THE NORTHERN EDGE OF THE DNIEPER-DONETS DEPRESSION." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 4(95) (2021): 25–33. http://dx.doi.org/10.17721/1728-2713.95.03.

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The main objective of this article is studying of electrical and acoustic parameters of Carbonic period terrigenous rocks of the eastern part of the northern edge of the Dnieper-Donets depression (DDD). It was determined that in atmospheric conditions the resistivity of dry extracted rocks (the specific electrical resistivity of framework of grains) varies from 6.522 kΩ×m to 2.782 MΩ×m (mean 1.033 MΩ×m), for sandstones – from 16.18 kΩ×m to 206.815 MΩ×m (mean 27.973 MΩ×m). The resistivity of rocks saturated with model of reservoir water (salinity M = 180 g/l) varies: for siltstones from 3.3 Ω×m to 26.8 Ω×m (mean 8.5 Ω×m), for sandstones from 2.9 Ω×m to 20.3 m (mean 8.2 Ω×m). In laboratory it was defined that in atmospheric conditions formation resistivity factor varies: for siltstones from 41.2 to 277.9 Ω×m (mean 96.2 Ω×m), for sandstones from 34 Ω×m to 238.5 Ω×m (mean 94.5 Ω×m). Physical modelling of reservoir conditions (temperature 94-126 °Ñ, confining stress 41-55 MPa, salinity M = 180 g/l) showed that the specific electrical resistivity varies: for siltstones from 0.4 Ω×m to 7.7 Ω×m (mean 2.1 Ω×m), and sandstones – from 0.4 Ω×m to 3.5 Ω×m (mean 1.3 Ω×m). Due to the closure of microcracks and the deformation of the pore space, the electrical resistance of rocks increases with increase of pressure. The regression dependence of the formation resistivity enlargement factor with pressure for the studied rocks manifest itself in second order polynomial. It was determined that in reservoir conditions the range of the formation resistivity factor varied: for siltstones from 132 to 2480 Ω×m (mean 562 Ω×m), for sandstones from 81 to 953 Ω×m (mean 339 Ω×m). Laboratory acoustic study of velocities of the P-waves in dry extracted rocks showed that this parameter varies: for siltstones from 2616 m/s to 4706 m/s (average 3940 m/s), for sandstones from 3660 m/s to 4971 m/s (average 4245 m/s). If rocks are saturated with model of reservoir water, velocities have higher values of P-waves: for siltstones from 3596 m/s to 5438 m/s (average 4681 m/s), for sandstones from 4302 m/s to 5463 m/s (average 4942 m/s). It was determined by physical modelling of reservoir conditions that velocities of P-waves vary: for siltstones from 3763 m/s to 6223 m/s (mean 5053 m/s), for sandstones from 4430 m/s to 5752 m/s (mean 5176 m/s). With the increase of pressure, the velocity of P-waves increases as well due to the closure of microcracks and the deformation of the pore space. The dependence of the increase in velocity from pressure is described by second order polynomial. The comprehensive analysis of electrical and acoustic parameters of condensed rocks has been resulted in a set of correlation ratios between reservoir, electric and elastic parameters of studied samples in normal and modeling conditions.

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Szalai, S., K. Szokoli, E. Prácser, M. Metwaly, M. Zubair, and L. Szarka. "An alternative way in electrical resistivity prospection: the quasi-null arrays." Geophysical Journal International 220, no. 3 (December 13, 2019): 1463–80. http://dx.doi.org/10.1093/gji/ggz518.

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SUMMARY While traditional geoelectric array configurations, such as the Wenner–Schlumberger or the dipole–dipole, can provide very good images of 1-D or robust 2-D structures, they are not sufficiently sensitive to those inhomogeneities that have a small effect on the surface electrical potential distribution. The detection and description of such inhomogeneities become possible by applying quasi-null arrays, which provide very small (close to zero) signals above a homogeneous half-space. The imaging properties of the members of an array series containing such arrays, the so-called γ11n arrays (n = 1–7), are demonstrated and compared to those of the most popular traditional arrays. Although the field applicability of the quasi-null arrays has been heavily questioned, it was demonstrated by our quasi-field analogue modelling experiments. The quasi-field tests also validated all of the numerical modelling results as follows: (1) many or all of the γ11n arrays were able to detect prisms and vertical sheets located at depths larger than those detectable by traditional geoelectric arrays, including the optimized Stummer configuration; (2) the horizontal resolution of the γ11n arrays proved to be better than the horizontal resolution of traditional arrays; (3) with n increasing, the γ11n arrays proved to be less sensitive to 1-D, but more sensitive to 2-D bodies. In case of high n values, the γ11n arrays may even be entirely insensitive to any 1-D structure. On the basis of the quasi-field experiments, γ11n arrays are expected to be very efficient to indicate bodies, or variations in time that only have a small impact on the surface electrical potential distribution (e.g. caves, mines, tunnels, tubes, cables, fractures, dykes), or small changes in the subsurface conditions (monitoring of dams or waste deposits). Data acquisition by both a traditional and a γ11n array, individual inversion of their data, and a joint interpretation of the results are recommended to obtain both a robust image and fine details of the subsurface.

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Kim, Hyelim, and Sunhee Lee. "Electrical Heating Performance of Graphene/PLA-Based Various Types of Auxetic Patterns and Its Composite Cotton Fabric Manufactured by CFDM 3D Printer." Polymers 13, no. 12 (June 19, 2021): 2010. http://dx.doi.org/10.3390/polym13122010.

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To evaluate the electrical heating performance by auxetic pattern, re-entrant honeycomb (RE), chiral truss (CT), honeycomb (HN), and truss (TR), using graphene/PLA (Polylactic acid) filament, were manufactured by CFDM (conveyor fused deposition modelling) 3D printer. In addition, HN and TR, which was indicated to have an excellent electrical heating property, were selected to verify the feasibility of applying fabric heating elements. The result of morphology was that the number of struts constituting the unit cell and the connected points were TR < HN < CT < RE. It was also influenced by the surface resistivity and electrical heating performance. RE, which has the highest number of struts constituting the unit cell and the relative density, had the highest value of surface resistivity, and the lowest value was found in the opposite TR. In the electrical heating performance of samples, the heat distribution of RE was limited even when the applied voltage was increased. However, HN and TR were diffused throughout the sample. In addition, the surface temperature of RE, CT, HN, and TR was about 72.4 °C, 83.1 °C, 94.9 °C, and 85.9, respectively as applied at 30 V. When the HN and TR were printed on cotton fabric, the surface resistivity of HN/cotton and TR/cotton was about 103 Ω/sq, which showed conductive material. The results of electrical heating properties indicated that the heat distribution of HN/cotton showed only in the region where power was supplied, but the TR/cotton was gradually expanded and presented stable electric heating properties. When 30 V was applied, the surface temperature of both samples showed more than 80 °C, and the shape was maintained stably due to the high thermal conductivity of the cotton fabric. Therefore, this study ensured that HN and TR show excellent electrical heating performance among four types of auxetic patterns with continuity.

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Dvorsky, Karl, Joachim Gwinner, and Hans-Dieter Liess. "A FIXED POINT APPROACH TO STATIONARY HEAT TRANSFER IN ELECTRIC CABLES." Mathematical Modelling and Analysis 16, no. 1 (June 24, 2011): 286–303. http://dx.doi.org/10.3846/13926292.2011.580436.

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In this paper we present a novel procedure for the determination of temperature in electric conductors. A Helmholtz-to-Poisson estimate is proved, that justifies to restrict the temperature dependence of the electrical resistivity to the conductor boundary. Hence we obtain a nonlinear potential problem for the relevant boundary temperatures, where the temperature dependence of the heat transfer coefficient is fully regarded. Using boundary integral operators, we represent the unknowns as the fixed point of a contraction. Finally a benchmark example is given in the rotationally symmetric case.

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Simyrdanis, Kleanthis, Ian Moffat, Nikos Papadopoulos, Jarrad Kowlessar, and Marian Bailey. "3D Mapping of the Submerged Crowie Barge Using Electrical Resistivity Tomography." International Journal of Geophysics 2018 (2018): 1–11. http://dx.doi.org/10.1155/2018/6480565.

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This study explores the applicability and effectiveness of electrical resistivity tomography (ERT) as a tool for the high-resolution mapping of submerged and buried shipwrecks in 3D. This approach was trialled through modelling and field studies of Crowie, a paddle steamer barge which sunk at anchor in the Murray River at Morgan, South Australia, in the late 1950s. The mainly metallic structure of the ship is easily recognisable in the ERT data and was mapped in 3D both subaqueously and beneath the sediment-water interface. The innovative and successful use of ERT in this case study demonstrates that 3D ERT can be used for the detailed mapping of submerged cultural material. It will be particularly useful where other geophysical and diver based mapping techniques may be inappropriate due to shallow water depths, poor visibility, or other constraints.

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Vyzhva, S., V. Onyshchuk, I. Onyshchuk, M. Reva, and O. Shabatura. "ELECTRICAL AND ACOUSTIC PARAMETERS OF LOWER PERMIAN CARBONATE ROCKS (WESTERN PART OF THE HLYNSKO-SOLOKHIVSKYI OF GAS-OIL-BEARING DISTRICT OF THE DNIEPER-DONETS BASIN)." Visnyk of Taras Shevchenko National University of Kyiv. Geology, no. 2 (89) (2020): 49–58. http://dx.doi.org/10.17721/1728-2713.89.07.

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The main objective of this article is to study electrical parameters of Lower Permian carbonate rocks of Western part of the Hlynsko-Solokhivskyi gas-oil-bearing district of the Dnieper-Donets Basin (DDB) in normal (atmospheric) and modeling (reservoir) conditions. In atmospheric conditions it has been revealed that the resistivity of dry extracted limestones (the specific electrical resistivity of framework of grains was measured) varies from 12.147 kΩ⋅m to 111.953 MΩ⋅m (mean 1.542 MΩ⋅m). The resistivity of saturated limestone samples with kerosene varies from 44.478 kΩ⋅m to 14.449 MΩ⋅m (mean 1.435 MΩ⋅m). The resistivity of dry and saturated with kerosene samples is almost the same. The resistivity of limestones saturated with model of reservoir water (salinity M = 190 g/l) is lower and varies from 1.11 Ω⋅m to 23.16 Ω⋅m (mean 3.12 Ω⋅m). It has been determined that formation resistivity factor of limestones in atmospheric conditions varies from 13.5 to 230 Ω⋅m (mean 32.5 Ω⋅m). In addition to resistivity, the parameter of relative permittivity of investigated limestones was studied. It was determined that relative permittivity of dry limestones varies from 3.0 to 7.5 (mean 4.2). Relative permittivity saturated samples of limestones with kerosene varies from 2.8 to 8.8 (mean 4.5) and practically does not differ from dry ones but significantly lower than values of samples saturated with model of reservoir water (from 655 to 9565, mean 4280). That means when pores of limestones are saturated with NaCl solution their relative permittivity increases rapidly – from hundreds to thousands times (on average 944 times). It can be explained by the high conductivity of model of reservoir water. Limestones saturated with NaCl solution have velocities of P-waves in the range from 3346 m/s to 4388 m/s (mean 4030 m/s), and velocities of Swaves – from 1753 m/s to 2121 m/s (average 1942 m/s). If rocks are saturated with kerosene then velocities have strictly higher values – P-waves from 3433 m/s to 4514 m/s (mean 4011 m/s) and S-waves – from 2137 m/s to 2464 m/s (average 2344 m/s). Physical modelling of reservoir conditions (temperature 50 °С, pressure 30 MPa) showed that the specific electrical resistivity varies from 0.81 Ω⋅m to 13.19 Ω⋅m (mean 2.67 Ω⋅m), and limestones – from 0.49 Ω⋅m to 7.81 Ω⋅m (mean 1.95 Ω⋅m). Also, "specific electrical resistivity – pressure" connection was investigated. Due to the closure of microcracks and the deformation of the pore space, the electrical resistance of rocks increases with increase of pressure. The regression dependence of the formation resistivity enlargement factor with pressure for the studied rocks has a linear character. It was determined that in reservoir conditions the range of the formation resistivity factor for limestones varied from 17.3 to 271.9 Ω⋅m (mean 50.7 Ω⋅m), and range of variation of porosity coefficient was from 0.040 to 0.169 Ω⋅m (mean 0.118 Ω⋅m). The comprehensive analysis of petrophysical data has been resulted in a set of correlation ratios between reservoir, electric and elastic parameters of studied limestones in normal and modeling conditions.

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Lacey, A. A. "Thermal runaway in a non-local problem modelling Ohmic heating: Part I: Model derivation and some special cases." European Journal of Applied Mathematics 6, no. 2 (April 1995): 127–44. http://dx.doi.org/10.1017/s095679250000173x.

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We consider the non-local problemwhich models the temperature when an electric current flows through a material with temperature dependent electrical resistivity f(u) > 0, subject to a fixed potential difference. It is found that for some special cases where f is decreasing andso the problem can be scaled to makethen:(a) for λ < 8 there is a unique steady state which is globally asymptotically stable: (b) for λ = 8 there is no steady state and u is unbounded; (c) for λ > 8 there is no steady state and u blows up for all x, – 1 < x < 1.

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Bouchekhou, Hocine, Hicham Allag, Mohamed Rachid Mekideche, Jean Lévêque, and Larbi Gueraiche. "New approach to study HTS bulk behavior for a fully superconducting motor design." European Physical Journal Applied Physics 92, no. 2 (November 2020): 20904. http://dx.doi.org/10.1051/epjap/2020200031.

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The originality of this work is to applied Amperian Approach for modelling HTS bulk especially in electrical motor applications. This approach has proven its efficiency in electrical materials having a constant conductivity. For HTS materials, the resistivity change brutally and have a non linear comportment through any external magnetic field variations. To success the modelisation, we have to create an iterative procedure. All simulation steps are based on the power law model for computing resistivity and current densities adding the fixed point method for non linear iterations. The majority of our results concern the current densities in the HTS bulk rotor with different critical currents constatations under mgnetic field created by three phase coils of the proposed superconducting synchronous motor (SSM) prototype. Some results are consolidated by numerical way using flux 2D software.

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Wang, Yu. "Concrete Electrical Resistivity At Varied Water, Chloride Contents And Porosity – Experiment, Modelling & Application." Advanced Materials Letters 11, no. 7 (July 1, 2020): 20071536. http://dx.doi.org/10.5185/amlett.2020.071536.

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Man, H. N., and X. D. Jing. "Network modelling of wettability and pore geometry effects on electrical resistivity and capillary pressure." Journal of Petroleum Science and Engineering 24, no. 2-4 (December 1999): 255–67. http://dx.doi.org/10.1016/s0920-4105(99)00047-9.

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Tabbagh, Jeanne, Anatja Samouëlian, Alain Tabbagh, and Isabelle Cousin. "Numerical modelling of direct current electrical resistivity for the characterisation of cracks in soils." Journal of Applied Geophysics 62, no. 4 (August 2007): 313–23. http://dx.doi.org/10.1016/j.jappgeo.2007.01.004.

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Gołębiowski, Jerzy, and Marek Zaręba. "Analytical modelling of the transient thermal field of a tubular bus in nominal rating." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 38, no. 2 (March 4, 2019): 642–56. http://dx.doi.org/10.1108/compel-02-2018-0078.

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Purpose The purpose of this paper is to analyse the dynamics of a thermal field generated in a tubular bus with rated current by using two models of electrical resistivity of copper. Design/methodology/approach The boundary-initial problem of the modified heat equation was formulated for the tubular bus. Analytical solutions were obtained by means of Green’s functions as the kernels of the integral operator inverse to the corresponding differential operator. The results were presented graphically and verified using the finite element method. The calculations were made by considering the example of the Storm Power Components tubular bus (USA). Findings Analytical field models were used to determine time- and space-variable heating curves, time constants and steady-state current ratings. Research limitations/implications This paper is related to the structure of a hollow cylinder. Other bus sections can be taken into account by using the coordinate systems of different curvilinear orthogonal symmetry. Originality/value Using the analytical method, the influence of the variable (temperature dependent) electrical resistivity on some important parameters and characteristics of the tubular bus was investigated. The system was considered as an element with distributed parameters.

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Mukanova, Balgaisha, Tolkyn Mirgalikyzy, and Dilyara Rakisheva. "Modelling the Influence of Ground Surface Relief on Electric Sounding Curves Using the Integral Equations Method." Mathematical Problems in Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/9079475.

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The problem of electrical sounding of a medium with ground surface relief is modelled using the integral equations method. This numerical method is based on the triangulation of the computational domain, which is adapted to the shape of the relief and the measuring line. The numerical algorithm is tested by comparing the results with the known solution for horizontally layered media with two layers. Calculations are also performed to verify the fulfilment of the “reciprocity principle” for the 4-electrode installations in our numerical model. Simulations are then performed for a two-layered medium with a surface relief. The quantitative influences of the relief, the resistivity ratios of the contacting media, and the depth of the second layer on the apparent resistivity curves are established.

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Lomov, Stepan V., Nikita A. Gudkov, and Sergey G. Abaimov. "Uncertainties in Electric Circuit Analysis of Anisotropic Electrical Conductivity and Piezoresistivity of Carbon Nanotube Nanocomposites." Polymers 14, no. 22 (November 8, 2022): 4794. http://dx.doi.org/10.3390/polym14224794.

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Electrical conductivity and piezoresistivity of carbon nanotube (CNT) nanocomposites are analyzed by nodal analysis for aligned and random CNT networks dependent on the intrinsic CNT conductivity and tunneling barrier values. In the literature, these parameters are assigned with significant uncertainty; often, the intrinsic resistivity is neglected. We analyze the variability of homogenized conductivity, its sensitivity to deformation, and the validity of the assumption of zero intrinsic resistivity. A fast algorithm for simulation of a gauge factor is proposed. The modelling shows: (1) the uncertainty of homogenization caused by the uncertainty in CNT electrical properties is higher than the uncertainty, caused by the nanocomposite randomness; (2) for defect-prone nanotubes (intrinsic conductivity ~104 S/m), the influence of tunneling barrier energy on both the homogenized conductivity and gauge factor is weak, but it becomes stronger for CNTs with higher intrinsic conductivity; (3) the assumption of infinite intrinsic conductivity (defect-free nanotubes) has strong influence on the homogenized conductivity.

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Doody, Jonathan J., Rona A. R. McGill, David Darby, and David K. Smythe. "Geophysical surveys of the East Kirkton Limestone, Viséan, West Lothian, Scotland." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 84, no. 3-4 (1993): 197–202. http://dx.doi.org/10.1017/s0263593300006003.

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ABSTRACTMagnetic and resistivity geophysical surveys conducted across the only known exposure of the East Kirkton Limestone have produced new information upon its extent. This is important to determine because of its unique faunal assemblage and possible hot spring deposition, suggesting a potential for precious metal mineralisation. Magnetic anomalies are attributed to basalts within the Bathgate Hills Volcanic Formation. Modelling of the magnetic data demonstrates a general dip to the west of about 25°, and the presence of significant local faulting. Modelling of vertical electrical sounding data shows the East Kirkton sequence (the limestone and associated beds) to be a low resistivity layer within the more highly resistive volcanic sequence. The East Kirkton sequence is seen to deepen to the west, and also to the north probably by faulting. Therefore the present exposure is the only near surface occurrence of the East Kirkton Limestone locally, but within the area of the survey no lateral limits to the formation are observed.

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Zhang, H., G. D. Egbert, A. D. Chave, Q. Huang, A. Kelbert, and S. Y. Erofeeva. "Constraints on the resistivity of the oceanic lithosphere and asthenosphere from seafloor ocean tidal electromagnetic measurements." Geophysical Journal International 219, no. 1 (July 11, 2019): 464–78. http://dx.doi.org/10.1093/gji/ggz315.

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SUMMARY The electromagnetic (EM) field generated by ocean tidal flow is readily detectable in both satellite magnetic field data, and in ocean-bottom measurements of electric and magnetic fields. The availability of accurate charts of tidal currents, constrained by assimilation of modern satellite altimetry data, opens the possibility of using tidal EM fields as a source to image mantle electrical resistivity beneath the ocean basins, as highlighted by the recent success in defining the globally averaged lithosphere–asthenosphere boundary (LAB) with satellite data. In fact, seafloor EM data would be expected to provide better constraints on the structure of resistive oceanic lithosphere, since the toroidal magnetic mode, which can constrain resistive features, is a significant component of the tidal EM field within the ocean, but is absent above the surface (in particular in satellite data). Here we consider this issue in more detail, using a combination of simplified theoretical analysis and 1-D and 3-D numerical modelling to provide a thorough discussion of the sensitivity of satellite and seafloor data to subsurface electrical structure. As part of this effort, and as a step toward 3-D inversion of seafloor tidal data, we have developed a new flexible 3-D spherical-coordinate finite difference scheme for both global and regional scale modelling, with higher resolution models nested in larger scale solutions. We use the new 3-D model, together with Monte Carlo simulations of errors in tidal current estimates, to provide a quantitative assessment of errors in the computed tidal EM signal caused by uncertainty in the tidal source. Over the open ocean this component of error is below 0.01 nT in Bz at satellite height and 0.05 nT in Bx on the seafloor, well below typical signal levels. However, as coastlines are approached error levels can increase substantially. Both analytical and 3-D modelling demonstrate that the seafloor magnetic field is most sensitive to the lithospheric resistance (the product of resistivity and thickness), and is more weakly influenced (primarily in the phase) by resistivity of the underlying asthenosphere. Satellite data, which contain only the poloidal magnetic mode, are more sensitive to the conductive asthenosphere, but have little sensitivity to lithospheric resistance. For both seafloor and satellite data’s changes due to plausible variations in Earth parameters are well above error levels associated with source uncertainty, at least in the ocean interior. Although the 3-D modelling results are qualitatively consistent with theoretical analysis, the presence of coastlines and bathymetric variations generates a complex response, confirming that quantitative interpretation of ocean tidal EM fields will require a 3-D treatment. As an illustration of the nested 3-D scheme, seafloor data at five magnetic and seven electric stations in the northeastern Pacific (41○N, 165○W) are fit with trial-and-error forward modelling of a local domain. The simulation results indicate that the lithospheric resistance is roughly 7 × 108 Ωm2. The phase of the seafloor data in this region are inconsistent with a sharp transition between the resistive lithosphere and conductive asthenosphere.

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YOSHIDA, Michiyuki, Simone FALCO, and Richard I. TODD. "Measurement and modelling of electrical resistivity by four-terminal method during flash sintering of 3YSZ." Journal of the Ceramic Society of Japan 126, no. 7 (July 1, 2018): 579–90. http://dx.doi.org/10.2109/jcersj2.17256.

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Sretenovic, Branislav. "Inadequacy of 1D, 2D and 3D Resistivity Inverse Modelling in the Presence of Electrical Anisotropy." Earth Sciences 8, no. 2 (2019): 102. http://dx.doi.org/10.11648/j.earth.20190802.14.

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Brazovskii, Konstantin S., Jacov S. Pekker, and Oleg S. Umanskii. "Modelling the Ability of Rheoencephalography to Measure Cerebral Blood Flow." Journal of Electrical Bioimpedance 5, no. 1 (August 8, 2019): 110–13. http://dx.doi.org/10.5617/jeb.962.

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Abstract Despite the long history of rheoencephalography (REG), some important aspects of the method are still debatable. Bioimpedance measurements offer great potential benefit for study of the human brain, but the traditional four or six electrode method suffers from potential misinterpretations and lack of accuracy. The objective of this paper is to study the possible mechanism of REG formation by means of numerical modelling using a realistic finite element model of the human head. It is shown that the cardiac related variations in electrical resistivity of the scalp contributes more than 60% to the REG amplitude, whereas the brain and cerebrospinal fluid are mutually compensated by each over.

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Journal articles on the topic 'Electrical resistivity modelling'

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