Bulk Electrical Conductivity Measurements Research Articles

Evaluation of soil salinity using the dielectric sensor WET-2

Context The electrical conductivity of the soil saturated paste extract (ECe) is used to estimate the soil salinity. Aims This study aims to develop simple or multiple linear regression models to estimate the ECe using soil properties measured by a dielectric sensor in the field. Methods The measurements of bulk electrical conductivity (ECb), soil temperature (T) and dielectric permittivity (εb) in agricultural fields were conducted using the WET-2 sensor. A total of 105 soil samples were obtained from agricultural fields in three regions of Greece. Key results A very strong positive correlation between ECb and ECe (r > 0.6 and P < 0.001) was obtained by using the Spearman’s correlation coefficients. Multiple linear regression models (MLR) were developed using only the parameters εb, ECb and T measured by the WET-2 in estimating ECe. Considering that the MLR models are site specific, the ECe could be reliably estimated by applying MLR models in regions with coarse textured soils. Contrarily, in regions with finer textured soils characterised by ECb values <1 dS m−1, additional soil parameters are required to be included in MLR models to estimate of ECe more accurately. In regions with soils characterised by high salinity (4 dS m−1 < ECe < 25 dS m−1), a simple linear regression model seems to be sufficient. Conclusions and implications As the WET-2 sensor measures simultaneously three soil properties in situ, it might be a valuable tool for estimating ECe, for the first centimetres of soil, in the case that the soil is not dry with relatively low clay content.

Application of a dagger probe for soil dielectric permittivity measurement by TDR

The most basic parameter of soil is volumetric water content (VWC). This parameter is typically determined indirectly, based on other parameters. Currently, a widely used method for indirect VWC determination is a method which is based on soil dielectric permittivity (DP) measurement, using the well-known Topp formula. The paper presents a novel probe for soil VWC and electrical conductivity (EC) measurement employing the above method. The new probe is going to be adopted on a mobile plant-watering machines used in precise agriculture e.g. for plants watering, thus it features a robust mechanical design and allows for instantaneous readout of VWC and EC values. The design of the probe mimics a dagger with three flat conductors forming a short-circuited coplanar waveguide with the space between the conductors filled with a mineral cold-curing resin. The resin filling the space between the bars improves the mechanical stiffness of the probe and ensures constant electrical parameters, which increases the measurement accuracy. In the first step, Ansys HFSS software was used to perform electromagnetic (EM), numerical simulations for the proposed solution, in order to determine the optimal electrical parameters of the probe. Next, a probe prototype was made to carry out laboratory tests. The measurements were performed with the use of a vector network analyzer (VNA) in the frequency range (3.74 MHz − 3 GHz). The measured complex reflection coefficients were transformed into the time domain with the use of the inverse Discrete Fourier Transform (IDFT). Based on the time distance between the reflections of an electric pulse traveling along the probe's sensing element, bulk dielectric permittivity of soil surrounding the probe can be calculated. A linear relation between the square root of DP and the pulse propagation time was obtained. Also, the probe was calibrated for bulk electrical conductivity measurements.

Black diamond powder: On the thermal oxidation and surface graphitization

Oxidation and graphitization are among the most interesting thermochemical characteristics of diamond to be explored. This is due to the influence of these phenomena on either degradation or promotion of the critical properties of diamonds. This article investigates the oxidation and graphitization of diamond powder using thermal analysis combined with X-ray diffraction, Raman spectroscopy, electron microscopy and bulk-electrical conductivity measurements. To this end, the thermokinetic characteristics of micrometre-sized diamond crystals with dominant (1 1 1) facet are investigated at various heating rates from 1 to 100 °C min−1, and the oxidation activation energy is determined to be 135.7 kJ mol−1. In contrast with thermal oxidation, the facile surface graphitization of diamond crystals is also studied as a possible way to promote the electrical conductivity of diamonds without affecting their bulk properties. This surface phase transition involves minimum atomic diffusion, with the crystalline relationship between the interfacial phases described as (0 0 2) graphite || (1 1 1) diamond. The surface-graphitized diamonds, which are black in appearance, exhibit a high value of electrical conductivity of 2100 S m−1. The effect of rapid heating is also confirmed using nanodiamond precursor. This article suggests an ultra-fast and economical method for surface graphitization of diamond crystals, enhancing their electrical performance.

Spatial and Temporal Variability of Soil Redox Potential, pH and Electrical Conductivity across a Toposequence in the Savanna of West Africa

Soil redox potential is an important factor affecting soil functioning. Yet, very few agronomy studies included soil redox potential in relation to soil processes. The objective of this study was to evaluate the spatial and temporal variation in soil redox potential and to determine the soil parameters affecting its variation. Soil redox potential, soil moisture, soil temperature, pH and bulk electrical conductivity were measured in upland rice fields during two growing seasons at six positions along an upland–lowland continuum, including two positions at the upland, two at the fringe and two at the lowlands in central Côte d’Ivoire (West Africa). The measurements were made at the following soil depths: 3, 8, 20 and 35 cm. Soil redox potential varied between 500 and 700 mV at the upland positions, 400 and 700 mV at the fringe positions and 100 and 750 mV at the lowland positions, and increased with soil depth. Variations in soil redox potential were driven by soil moisture, bulk electrical conductivity and soil organic carbon. We concluded that for proper interpretation of soil redox potential, sampling protocols should systematically include soil pH, moisture and bulk electrical conductivity measurements.

Supramolecular Nanowires from an Acceptor-Donor-Acceptor Conjugated Chromophore.

Oligothiophene derivatives have been extensively studied as p-type semiconducting materials in organic electronics applications. This work reports the synthesis, self-assembly and photophysical properties of acceptor-donor-acceptor (A-D-A)-type oligothiophene derivatives by end-group engineering of quaterthiophene (QT) with naphthalene monoimide (NMI) chromophores that are further connected to a trialkoxy benzamide wedge. Conjugation to the NMI units reduces the HOMO-LUMO gap significantly, and consequently the absorption spectrum exhibits a bathochromic shift of about 50 nm compared with QT. Furthermore, extended H-bonding interactions among the amido groups of the peripheral wedges produce entangled fibrillar nanostructures and gelation in hydrocarbon solvents such as methylcyclohexane, wherein the A-D-A chromophore exhibits typical H-aggregation. On the contrary, the fact that the same chromophore, lacking only the amido units, does not produce gels or H-aggregates indicates strong impact of H-bonding on the self-assembly. Computational studies revealed the electronic properties of the chromophore and predicted the geometry of a dimer in the H-aggregate that reasonably matches with the experimental results. Bulk electrical conductivity measurements determined an excellent conductivity of 2.3×10-2 S cm-1 for the H-aggregated system (OT-1), which is two orders of magnitude higher than that of the same chromophore lacking the amido groups (OT-2).

Transfer Function and Time Series Outlier Analysis: Modelling Soil Salinity in Loamy Sand Soil by Including the Influences of Irrigation Management and Soil Temperature

AbstractIn variable interval irrigation, simply including soil salinity data in the soil salinity model is not valid for making predictions, because changes in irrigation frequency must also be taken into account. This study on variable interval irrigation used capacitance soil sensors simultaneously to obtain hourly measurements of bulk electrical conductivity (σb), soil temperature (t) and soil water content (θ). Observations of σb were converted so that the electrical conductivity of the pore water (σp) could be estimated as an indicator of soil salinity. Values of θ, t and σp were used to test a mathematical model for studying how σp cross‐correlates with t and θ to predict soil salinity at a given depth. These predictions were based on measurements of σp, t, and θ at a shallow depth. As a result, prediction at shallow depth was successful after integrating intervention analysis and outlier detection into the seasonal autoregressive integrated moving average (ARIMA) model. We then used the (multiple‐input/one‐output) transfer function models to logically predict soil salinity at the depths of interest. The model could also correctly determine the effect of the irrigation event on soil salinity. Copyright © 2017 John Wiley & Sons, Ltd.

Exploring ice content on partially saturated frozen soils using dielectric permittivity and bulk electrical conductivity measurements

The present paper explores the use of the measurement of bulk electric conductivity and relative dielectric permittivity during freezing and thawing to estimate the ice content of two different partially saturated soils. The soils (Castelldefels fine sand and Barcelona clayey silt) were prepared at different degrees of saturation and dry densities at room temperature. Different target temperatures were used, which were reached at varying freezing rates and controlled with a thermal bath. Models were used to fit electrical conductivity and relative dielectric permittivity results under full unfrozen liquid and maximum ice conditions. The extension of these models allows estimating ice content on partially saturated soils at different porosities.

Dispersion, migration, and ‘network-like’ structure formation of multiwall carbon nanotubes in co-continuous, binary immiscible blends of polyamide 6 and acrylonitrile-butadiene-styrene copolymer during simultaneous melt-mixing

Multiwall carbon nanotubes (MWNTs) were melt-mixed in polyamide 6 (PA6) and acrylonitrile–butadiene–styrene (ABS) copolymer blends using a simultaneous mixing protocol in order to investigate the state of dispersion of MWNTs in PA6/ABS blends. The blend composition was varied from 40/60 (wt/wt) to 60/40 (wt/wt) in PA6/ABS blends, which showed ‘co-continuous’ morphology in the presence of MWNTs. State of dispersion of MWNTs in these blends was assessed through bulk electrical conductivity measurements, morphological analysis, solution experiments, and UV-vis spectroscopic analysis. MWNTs were subsequently modified with a novel organic modifier, sodium salt of 6-aminohexanoic acid (Na-AHA), to improve the state of dispersion of MWNTs. Blends with unmodified MWNTs exhibited the DC electrical conductivity in the range ∼10−11 to ∼10−5 S/cm, whereas blends with Na-AHA-modified MWNTs exhibited DC electrical conductivity in the range ∼10−7 to ∼10−5 S/cm. The reduction in MWNTs ‘agglomerate’ size (∼73.7 μm for 40/60 blend with unmodified MWNTs to ∼59.9 μm in the corresponding blend with Na-AHA-modified MWNTs) was observed through morphological analysis. The rheological studies showed increased complex viscosity and storage moduli in lower frequency region in case of blends with Na-AHA-modified MWNTs confirming a refined ‘network-like’ structure of MWNTs. POLYM. ENG. SCI., 55:443–456, 2015. © 2014 Society of Plastics Engineers

Determination of Water Saturation Using Gas Phase Partitioning Tracers and Time‐Lapse Electrical Conductivity Measurements

Water saturation is an important indicator of contaminant distribution and plays a governing role in contaminant transport within the vadose zone. Understanding the water saturation distribution is critical for both remediation and contaminant flux monitoring in unsaturated environments. In this work, we propose and demonstrate a method of remotely determining water saturation levels using gas phase partitioning tracers and time‐lapse bulk electrical conductivity measurements. The theoretical development includes the partitioning chemistry for the tracers we demonstrate (ammonia and carbon dioxide), as well as a review of the petrophysical relationship governing how these tracers influence bulk conductivity. We also investigate methods of utilizing secondary information provided by electrical conductivity breakthrough magnitudes induced by the tracers. We test the method on clean, well characterized, intermediate‐scale sand columns under controlled conditions. Results demonstrate the capability to accurately monitor gas breakthrough curves along the length of the column according to the corresponding electrical conductivity response, and to adequately determine partitioning coefficients, leading to accurate water saturation estimates. This work is motivated by the need to develop effective characterization and monitoring techniques for contaminated deep vadose zone environments, and provides a proof‐of‐concept toward uniquely characterizing and monitoring water saturation levels at the field scale and in three‐dimensions using electrical resistivity tomography.

Filler reaggregation and network formation time scale in extruded high‐density polyethylene/multiwalled carbon nanotube composites

AbstractA high‐density polyethylene (HDPE) masterbatch containing 20.2 wt% multiwalled carbon nanotubes (MWNTs) was melt diluted with neat HDPE using two different methods: a twin screw microcompounder and a single‐screw extruder. The electrical properties of these composites were assessed using bulk electrical conductivity measurements, their mechanical properties were evaluated using tensile tests and dynamic mechanical analysis (DMA), and percent crystallinity was determined by wide angle x‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). A percolation threshold (pc) of 4.5 wt% MWNTs was found in compression‐molded samples. Extruded samples were prepared with nanotube concentrations below and above the compression‐molded percolation threshold (2 and 7 wt% MWNTs) and passed through the extruder twice before entering a low‐shear melt annealing zone. Different melt annealing times were used and their effects on the electrical and mechanical properties of the resulting quench‐cooled composites were evaluated. Results showed that extruded composites were nonconductive, indicating that a conductive nanotube network did not form on the time scale of these experiments. Annealing time also did not affect significantly the mechanical properties of the resulting solid composites. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

Combined estimation of effective electrical conductivity and permittivity for soil monitoring

The mapping of moisture content, composition, and texture of soils is attracting a growing interest, in particular with the goal of evaluating threats to soil quality, such as soil salinization. Fast noninvasive geophysical surveys are often used in this context. The aim of this work was to study constitutive models that can be used to parameterize electrical conductivity and permittivity starting from a unifying conceptual approach, and to evaluate whether the information carried by one measurement type can be used to identify soil parameters that are then used to predict the other geophysical quantity. To this end, a recently developed constitutive model was extended and modified to consider the grain surface conductivity, a critical component in most natural situations. The extended model was successfully tested against laboratory measurements. In addition, the new model was compared against five other equations that use similar soil parameterizations. It was concluded that only three out of the five selected models yield similar predictions, while the remaining two predict a different geophysical response for the same soil texture. Following this analysis, a methodology was developed to estimate soil salinity starting from the simultaneous measurements of bulk electrical conductivity and permittivity and validating this methodology against laboratory experiments. The method is valid in situations where the conductivity of the pore water remains approximately constant during the measurement period. Key features of the approach proposed to map soil salinization are (1) simplicity, (2) absence of fitting parameters, and (3) the fact that moisture content does not need to be measured or estimated independently. The methodology was tested on a large number of soil samples and proved robust and accurate.

TDR pressure cell for monitoring water content retention and bulk electrical conductivity curves in undisturbed soil samples

AbstractThe water retention curve (θ(ψ)), which defines the relationship between soil volumetric water content (θ) and matric potential (ψ), is of paramount importance in characterizing the hydraulic behaviour of soils. However, few methods are so far available for estimating θ(ψ) in undisturbed soil samples. We present a new design of TDR‐pressure cell (TDR‐Cell) for estimating θ(ψ) in undisturbed soil samples. The TDR‐Cell consists of a 50‐mm‐long and 50‐mm internal diameter stainless steel cylinder (which constitutes the outer frame of a coaxial line) attached to a porous ceramic disc and closed at the ends with two aluminium lids. A 49‐mm‐long and 3‐mm‐diameter stainless steel rod, which runs longitudinally through the centre of the cylinder, constitutes the inner rod of a coaxial TDR probe. The TDR‐Cell was used to determine the θ(ψ) curves of a packed sand and seven undisturbed soil samples from three profiles of agricultural soils. These θ(ψ) curves were subsequently compared to those obtained from the corresponding 2‐mm sieved soils using the pressure plate method. Measurements of bulk electrical conductivity, σa, as a function of the water content, σa(θ), of the undisturbed soil samples were also performed. An excellent correlation (R2 = 0·988) was found between the θ values measured by TDR on the different undisturbed soils and the corresponding θ obtained from the soil gravimetric water content. A typical bimodal θ(ψ) function was found for most of the undisturbed soil samples. Comparison between the θ(ψ) curves measured with the TDR‐Cell and those obtained from the 2‐mm sieved soils showed that the pressure plate method overestimates θ at low ψ values. The σa(θ) relationship was well described by a simple power expression (R2 > 0·95), in which the power factor, defined as tortuosity, ranged between 1·18 and 3·75. Copyright © 2011 John Wiley & Sons, Ltd.

Electrical, mechanical, and glass transition behavior of polycarbonate-based nanocomposites with different multi-walled carbon nanotubes

Five commercially available multi-walled carbon nanotubes (MWNTs), with different characteristics, were melt mixed with polycarbonate (PC) in a twin-screw micro compounder to obtain nanocomposites containing 0.25–3.0 wt.% MWNT. The electrical properties of the composites were assessed using bulk electrical conductivity measurements, the mechanical properties of the composites were evaluated using tensile tests and dynamic mechanical analysis (DMA), and the thermal properties of the composites were investigated using differential scanning calorimetry (DSC). Electrical percolation thresholds ( p cs) were observed between 0.28 wt.% and 0.60 wt.%, which are comparable with other well-dispersed melt mixed materials. Based on measurements of diameter and length distributions of unprocessed tubes it was found that nanotubes with high aspect ratios exhibited lower p c s, although one sample did show higher p c than expected (based on aspect ratio) which was attributed to poorer dispersion achieved during mixing. The stress–strain behavior of the composites is only slightly altered with CNT addition; however, the strain at break is decreased even at low loadings. DMA tests suggest the formation of a combined polymer-CNT continuous network evidenced by measurable storage moduli at temperatures above the glass transition temperature ( T g ), consistent with a mild reinforcement effect. The composites showed lower glass transition temperatures than that of pure PC. Lowering of the height of the tan δ peak from DMA and reductions in the heat capacity change at the glass transition from DSC indicate that MWNTs reduced the amount of polymer material that participates in the glass transition of the composites, consistent with immobilization of polymer at the nanotube interface.

Dispersion of multiwall carbon nanotubes in blends of polypropylene and acrylonitrile butadiene styrene

AbstractState of dispersion of purified multiwall carbon nanotubes (p‐MWNT) in the presence of neutralized MWNT (n‐MWNT) in aqueous solution was assessed through UV–Visible spectroscopy, dynamic light scattering measurements, and solution experiments. Raman spectroscopic analysis revealed that debundling of p‐MWNT in the presence of n‐MWNT in aqueous solution was persistent even in the solid mixture, which was supported by transmission electron microscopic analysis. The proposed mechanism behind the improved dispersion of p‐MWNT in the presence of n‐MWNT in aqueous solution has been based on the electrostatic charge repulsion between negatively charged n‐MWNT. The state of dispersion of p‐MWNT in the presence of n‐MWNT in 45/55 polypropylene/acrylonitrile butadiene styrene (PP/ABS) blends was assessed through Raman spectroscopic analysis, bulk electrical conductivity measurements, solution experiment, and crystallization studies. Raman spectroscopic analysis indicated that the state of dispersion of MWNT was improved with increasing n‐MWNT content of the mixture. This strategy led to a remarkable increase in the bulk electrical conductivity of 45/55 PP/ABS blends at 3 wt% MWNT content and was strongly dependent on the concentration of n‐MWNT in the mixture. Differential scanning calorimetric measurements along with solution experiments revealed the subsequent migration of MWNT from the PP phase to the ABS phase in the blends during melt‐mixing in the presence of higher fraction of n‐MWNT. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Accuracy of Bulk Electrical Conductivity Measurements with Time Domain Reflectometry

Accurate determination of bulk electrical conductivity with time domain reflectometry (TDR) requires calibration or direct measurement of the probe constant and the cable resistance. The aims of this study were threefold. First, the accuracy of an analytical expression for the direct determination of the probe constant was evaluated for three TDR probe designs by comparing the analytical result with the probe constant obtained by calibration to TDR measurements in solutions with varying electrical conductivity. Second, the accuracy of direct measurement of cable resistance was compared with the accuracy that can be achieved by calibrating this resistance. The uncertainty in directly measured and calibrated probe and cable properties was determined in a Monte Carlo analysis. The results showed that the analytical expression for the probe constant and calibration of the probe constant do not provide significantly different estimates when the uncertainty in both approaches is considered; however, the uncertainty in the calibrated probe constants was lower than or similar to the uncertainty in the direct measurements. Directly measured and calibrated cable resistance differed, which was attributed to recording time issues. It was concluded that calibration of probe and cable parameters should be preferred over direct measurements to achieve accurate bulk electrical conductivity measurements. The final aim of this study was to quantify how the various sources of uncertainty identified in this study affect the accuracy of TDR bulk conductivity measurements. This uncertainty analysis showed that the accuracy of TDR ranges between 0.6 and 1.2% of the bulk electrical conductivity if the reflection coefficient varies between −0.75 and 0.75. Outside this range, the accuracy of the bulk electrical conductivity measurements made with TDR is lower.

Particle shape characterization using angle of repose measurements for predicting the effective permittivity and electrical conductivity of saturated granular media

The particle shape of sediments, soils, and rocks affects the packing of the material and the subsequent pore geometry; it therefore influences important transport properties, such as electrical conductivity, dielectric permittivity, diffusion coefficient, thermal conductivity, and hydraulic conductivity. It is difficult to quantify the “average” shape characteristics of a granular material so a method, which would capture the three‐dimensional shape characteristics of a granular material in regards to its packing geometry, would be of great benefit. In this article we examine the use of the angle of repose and the maximum angle of stability of a slope of granular material poured into water, as a simple and rapid method of quantifying its “effective” particle shape. A two‐stage concept is discussed relating the measured slope angles to the aspect ratio of an equivalent oblate ellipsoidal particle and using this aspect ratio for predicting the effective permittivity and bulk electrical conductivity of isotropic packings of granular materials. The slope angle‐aspect ratio relationships were established using measurements of bulk electrical conductivity of monosized spherical glass beads and nonspherical sand and tuff grains packed in water to different porosities. This empirical relationship, the choice of an oblate geometry to represent particle shape, and a heuristic mixing model accounting for the effect of neighboring particles on the internal electrical field were tested using measurements of the effective permittivity for those granular media. Good agreement was found between the model predictions and measurements, indicating the physical significance of the above relationships and quantifiers. We have also tested and found high correlations between slope angles and a shape factor determined by image analysis of two‐dimensional particle micrographs. We do not, however, propose to use it for routine particle shape characterization because of the insufficiently informative viewing of oblates from above and because of the expensive equipment and extensive work involve with it. Instead, we propose to use the easily measurable slope angles for routine particle shape characterization because of its simplicity and also because of its beneficial sensitivity to surface roughness and particle angularity effects beyond the aspect ratio of a smooth equivalent ellipsoid.

COAXIAL MULTIPLEXER FOR TIME DOMAIN REFLECTOMETRY MEASUREMENT OF SOILWATER CONTENT AND BULK ELECTRICAL CONDUCTIVITY

Time domain reflectometry (TDR) is increasingly used for measurement of soil water content and bulkelectrical conductivity in agricultural, hydrological, environmental, and infrastructure research and development. TheTDR technique uses reflections (wave forms), from a probe buried in the soil, of a fast rise time voltage step. The advent ofautomatic systems for collecting many TDR wave forms has brought the need for a multiplexer to connect the probes to aTDR instrument without introducing distortion of the wave form. A 16-channel (1P16T), 50 .coaxial multiplexer wasdeveloped to switch the TDR signal. Control is by synchronous serial addressing using three lines capable of producingTTL level signals similar to those from the parallel port of a personal computer. The multiplexer has 16 jumper selectableaddresses. Testing on five multiplexers showed that quiescent power consumption was 6 mA at 12 VDC, peak powerconsumption was 101 mA, and average power consumption during switching was 54 mA. Wave form placement on a cabletester screen was not affected by the multiplexer channel used. The standard deviation (SD) of horizontal placement was0.012 ns which compares favorably to the 15.6 ns full screen width of the wave form (five multiplexers by 16 channelseach = 80 measurements; 30 cm probe length). Multiplexer channel also had negligible effect on computed travel times ofthe TDR pulse in a water content probe. The SD of 0.011 ns for a mean travel time of 8.68 ns was only slightly larger thanthe SD of 0.007 ns obtained when 80 wave forms were captured using the first channel of one multiplexer. CorrespondingSD values for water content were 0.0006 and 0.0004 m3 m3, respectively. The multiplexer used and the multiplexerchannel had no important effect on the wave form voltage levels needed for determination of bulk electrical conductivity(BEC). The ratio of final voltage to incident voltage, which is directly proportional to conductivity, had a SD of 0.0002when measured 80 times on channel one of one multiplexer and a SD of 0.0006 when measured once on each of the 16channels of five multiplexers. Compared with a TDR probe connected directly to the cable tester, adding one multiplexerin series caused no change in travel time or water content, while adding two multiplexers in series caused a change inwater content of 0.003 m3 m3. As each multiplexer was added to the system the voltage ratio increased by 2% in areproducible and expected way that can be included in system calibration for BEC measurements. The multiplexerdeveloped is reliable and accurate for measurements of soil volumetric water content and bulk electrical conductivity.

Field scale patterns of soil water storage from non-contacting measurement of bulk electrical conductivity. Note : Kachanoski, R G; de Jong, E; Van Wesenbeeck, I J Can J Soil SciV70, N3, Aug 1990, P537–541

Field scale patterns of soil water storage from non-contacting measurement of bulk electrical conductivity. Note : Kachanoski, R G; de Jong, E; Van Wesenbeeck, I J Can J Soil SciV70, N3, Aug 1990, P537–541

Measurement of Inverted Electrical Conductivity Profiles Using Electromagnetic Induction

AbstractDue to sharp discrepancies in the relative response of the horizontal and vertical coil configurations of the Geonics Limited EM‐38 electromagnetic induction soil conductivity meter for the top 15 cm of soil, the accuracy of measurement of bulk electrical conductivity for soil having a high surface electrical conductivity relative to deeper depths (i.e., an inverted electrical conductivity profile) has been unreliable. Two new approaches have been developed to compensate for these discrepancies, either through compensations in the vertical coil configuration response curve or the reestablishment of EM0,H adjustment curves utilizing data solely from inverted conductivity profiles. Both approaches yield more consistently reliable calculated bulk soil electrical conductivities when compared to measured electrical conductivities using the four‐electrode probe. The latter approach, however, appears to be more accurate.

Measurement of bulk electrical conductivity of hydrocarbon liquids

Measurement of bulk electrical conductivity of hydrocarbon liquids