A PARADOX IN APPARENT RESISTIVITY MEASUREMENTS OVER A GROUND SECTION WITH CONDUCTIVE SUBSTRATUM

Geophysics ◽  
1974 ◽  
Vol 39 (1) ◽  
pp. 93-94 ◽  
Author(s):  
B. N. Satpathy
Keyword(s):  
Apparent Resistivity ◽  
Critical Value ◽  
Surface Electrode ◽  
Conductive Layer ◽  
Electrode Arrays ◽  
Opposite Result ◽  
Resistivity Measurements ◽  
Opposite Manner ◽  
Value Changes ◽  
Lower Resistivity

It is generally accepted that the resistivity of the top layer largely influences the apparent resistivity measured through conventional surface electrode arrays. Thus, intuitively it would be assumed that the overlaying of a conductive layer would give an apparent resistivity which is less than the value obtained without the conducting cover and an opposite result would be obtained by introducing a resistive top layer. Though this belief is valid for many geoelectric sections, it is here shown that for a two‐layer section with [Formula: see text], if the top portion of the first layer is replaced with a layer of higher or lower resistivity, the apparent resistivity value changes in an opposite manner after a critical value of the electrode separation: the apparent resistivity for large separations is decreased due to the introduction of the resistive top layer. It is intended in this note to elucidate this paradox through a suitable example.

scholarly journals Corrections of surface fissure effect on apparent resistivity measurements

2014 ◽  
Vol 200 (2) ◽  
pp. 1118-1135 ◽  
Author(s):  
J. Gance ◽  
P. Sailhac ◽  
J.-P. Malet
Keyword(s):  
Apparent Resistivity ◽  
Resistivity Measurements

The effects of sulfuric acid on the creep, recrystallization, and electrical properties of ice

2003 ◽  
Vol 81 (1-2) ◽  
pp. 395-400 ◽  
Author(s):  
D Iliescu ◽  
I Baker ◽  
X Li
Keyword(s):  
Electrical Resistivity ◽  
Sulfuric Acid ◽  
Single Crystals ◽  
Equal Channel Angular Extrusion ◽  
Boundary Migration ◽  
Constant Load ◽  
Tensile Creep ◽  
Grain Boundary Migration ◽  
Resistivity Measurements ◽  
Lower Resistivity

Both constant load creep and recrystallization are investigated using single crystals of 70–170 ppb sulfuric-acid-doped and -undoped ice. Both sets of crystals exhibited strains in excess of 200% under tensile creep. The undoped specimens reached these strains roughly twice as fast as the doped specimens. After large local strains were imparted to cuboidal single crystals using equal channel angular extrusion at –2°C and subsequent annealing at the same temperature, recrystallization occurred. It was found that a higher concentration of H2SO4 retarded both recrystallization and the subsequent grain-boundary migration. Direct current electrical resistivity measurements performed on polycrystalline, sulfuric-acid-doped (3 ppm) ice at –10°C showed a much lower resistivity in the grain boundaries than in the lattice. PACS No.: 81.90

scholarly journals Numerical Modeling of the Effects of Electrode Spacing and Multilayered Concrete Resistivity on the Apparent Resistivity Measured Using Wenner Method

2020 ◽  
Author(s):  
Karthick Thiyagarajan ◽  
Parikshit Acharya ◽  
Lasitha Piyathilaka ◽  
sarath kodagoda
Keyword(s):  
Contact Area ◽  
Apparent Resistivity ◽  
Resistivity Measurement ◽  
Gaussian Process Regression ◽  
Electrode Spacing ◽  
Electrical Resistivity Measurement ◽  
Resistivity Measurements ◽  
Electrode Contact ◽  
Concrete Resistivity ◽  
Moisture Conditions

Smart Sensing technologies can play an important role in the conditional assessment of concrete sewer pipe linings. In the long-term, the permeation of acids can deteriorate the pipe linings. Currently, there are no proven sensors available to non-invasively estimate the depth of acid permeation in real-time. The electrical resistivity measurement on the surface of the linings can indicate the sub-surface acid moisture conditions. In this study, we consider acid permeated linings as a two resistivity layer concrete sample, where the top resistivity layer is assumed to be acid permeated and the bottom resistivity layer indicates normal moisture conditions. Firstly, we modeled the sensor based on the four-probe Wenner method. The measurements of the developed model were compared with the previous studies for validation. Then, the sensor model was utilized to study the effects of electrode contact area, electrode spacing distance and two resistivity layered concrete on the apparent resistivity measurements. All the simulations were carried out by varying the thickness of top resistivity layer concrete. The simulation study indicated that the electrode contact area has very minimal effects on apparent resistivity measurements. Also, an increase in apparent resistivity measurements was observed when there is an increase in the distance of the electrode spacing. Further, a machine learning approach using Gaussian process regression modeling was formulated to estimate the depth of acid permeated layer

scholarly journals Electrical Resistivity Profiles and Temperatures in the Ross Ice Shelf

1976 ◽  
Vol 16 (74) ◽  
pp. 307-308
Author(s):  
C.R. Bentley
Keyword(s):  
Electrical Resistivity ◽  
Computer Program ◽  
Depth Profile ◽  
Apparent Resistivity ◽  
Ice Shelf ◽  
Resistivity Measurements ◽  
Ross Ice Shelf ◽  
Field Season ◽  
A Site ◽  
Temperature Depth

AbstractDuring the 1973-74 Antarctic field season, two electrical resistivity profiles were completed along directions perpendicular to each other at a site in the south-easternpart of the Ross Ice Shelf. These profiles differ from each other only at short electrode spacings (less than 10 m) indicating no measurable horizontal anisotropy below the uppermost firn zone. The shape of the apparent resistivity curves is similar to that found by Hochstein on the Ross Ice Shelf near Roosevelt Island, but is displaced toward lower resistivities despite the colder 10 m temperature (—29°C instead of —26°C) at the more southerly site. Some factor other than temperature must therefore be effective in determining the overall magnitude of the resistivities in the shelf, although the variation with depth can still be expected to be primarily a temperature phenomenon.A computer program has been written to calculate apparent resistivities based on Crary’s analysis of temperatures in an ice shelf. Results are not yet available; when completed they should indicate the sensitivity of the resistivity measurements to differences in the temperature- depth profile, and hence their usefulness in estimating bottom melt/freeze rates.

THE INTERPRETATION OF DIRECT CURRENT RESISTIVITY MEASUREMENTS

Geophysics ◽  
1978 ◽  
Vol 43 (3) ◽  
pp. 610-625 ◽  
Author(s):  
D. W. Oldenburg
Keyword(s):  
Continuous Function ◽  
Direct Current ◽  
Inverse Theory ◽  
Iterative Technique ◽  
Electrode Arrays ◽  
Resistivity Measurements ◽  
The Earth ◽  
Resistivity Model ◽  
Surface Observations ◽  
Layered Half Space

The linearized inverse theory of Backus and Gilbert has been used to invert potential difference measurements obtained from direct current resistivity soundings. The resistivity is assumed to be a continuous function of depth, hence many of the difficulties encountered when assuming that the earth is a layered half‐space are avoided. An iterative technique is used to construct a resistivity model whose calculated responses agree with the observations, and the model is then appraised to find those features which are uniquely determined by the surface observations. Also, the existence of the Fréchet kernels allows direct comparisons of the resolution provided by various electrode geometries and thus the design of electrode arrays to enhance resolution becomes more feasible.

Estimation of muscle fiber conduction velocity using surface electrode arrays

2004 ◽  
Vol 2004.6 (0) ◽  
pp. 111-112
Author(s):  
Hikari UDO ◽  
Kensuke USUI ◽  
Tomohisa INADA ◽  
Yoshihiko TAGAWA ◽  
Naoto SHIBA
Keyword(s):  
Conduction Velocity ◽  
Muscle Fiber ◽  
Surface Electrode ◽  
Electrode Arrays ◽  
Muscle Fiber Conduction Velocity

THREE‐DIMENSIONAL RESISTIVITY AND INDUCED‐POLARIZATION MODELING USING BURIED ELECTRODES

Geophysics ◽  
1977 ◽  
Vol 42 (5) ◽  
pp. 1006-1019 ◽  
Author(s):  
Jeffrey J. Daniels
Keyword(s):  
Electrical Properties ◽  
Apparent Resistivity ◽  
Three Dimensional ◽  
Equipotential Surface ◽  
Induced Polarization ◽  
The Body ◽  
Surface Electrode ◽  
Surface Integral ◽  
Drill Holes ◽  
Resistivity Modeling

The three‐dimensional induced‐polarization and resistivity‐modeling problem for buried source and receiver electrodes is solved by using a modified form of Barnett’s surface‐integral technique originally developed for surface‐electrode configurations. Six different buried electrode configurations are considered in this study: three types of hole‐to‐hole configurations, hole‐to‐surface and surface‐to‐hole configurations, and the single hole (bipole‐bipole) configuration. Results show there is no “best” method for all situations encountered in the field. The choice of method depends upon depth of the body, spacing of drill holes, and electrical properties of the body. In hole‐to‐hole measurements, the geometric factor (necessary for the computation of the apparent resistivity) becomes infinitely large or infinitely small whenever the receiving bipole is placed at a depth so that it lies on a zero equipotential surface. This leads to the formation of apparent resistivity anomalies that are extremely sensitive to the presence of the body but that are also complicated and not easily correlated with the position of the body. It is shown that diagnostic and easily interpretable anomalies are obtained by selecting the proper source‐receiver configurations.

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