Variation Of Electrical Conductivity Research Articles

Predicting the Electrical Conductivity of Partially Saturated Frozen Porous Media, a Fractal Model for Wide Ranges of Temperature and Salinity

AbstractThe quantitative determination of liquid water content and salinity in soils is crucial for the preservation of hydrological environments and engineering infrastructures, especially in frozen regions. Electrical conductivity, as a fundamental physical parameter in electrical and electromagnetic non‐destructive techniques, varies significantly with the physical and chemical properties, such as pore water conductivity, salinity, water saturation, and temperature. In this study, accounting for pore size and tortuous length following fractal distributions, we develop a new capillary bundle model for variation of electrical conductivity as a function of temperature in broad water saturation and salinity ranges. In this new model, we consider the contributions of bulk and surface conductivities to the total electrical conductivity. To test this model, a series of laboratory experiments were carried out for different initial water saturations and salinities using an electrical resistance apparatus and a nuclear magnetic resonance method. The experimental results show that unfrozen water saturation and ionic concentration affect the electrical conductivity of unsaturated frozen soils. Furthermore, the proposed model is capable of fitting the main trends of the experimental data from the literature and acquired in this study in unfrozen‐frozen conditions for different water contents. Relying on the proposed model, we also determine the expression of the apparent formation factor, which is significantly sensitive to porosity, water saturation, and temperature. The predicted values of the apparent formation factor also agree very well with the experimental data. This new capillary bundle model provides a new perspective in interpreting electrical monitoring to easily deduce changes in key variables in the cryosphere such as liquid water content and moisture gradients.

Sub-micron porous Si-C/graphite anode with interpenetrated 3D conductive networks towards high-performance lithium-ion batteries

Silicon (Si) has been envisaged as the most promising anode candidate for future lithium-ion batteries with high energy density and large power owing to its high theoretical capacity and abundance. However, the inherent drawbacks of Si anodes such as low electrical conductivity and volume variation seriously hinder their commercial scalable application. Here we demonstrate a magnesiothermic reduction process for converting marigold structured silica precursor into sub-micron silicon replicas. The complicated structured silica was converted into co-continuous composites of silicon, graphite and amorphous carbon layer by in-situ generation. This electrode delivers excellent rate capability with a discharge specific capacity of 631.7 mAh g−1 at 3 A g−1 and high cycling stability of 1114.9 mAh g−1 after 200 cycles at 0.1 A g−1. Moreover, the coulombic efficiency increased rapidly from the initial 62–97.3% after only 10 cycles and 98.8% can be obtained with negligible fading after 200 cycles. Remarkably, some byproduct partially decomposed from surfactant can be in-situ derived into amorphous carbon layer deposited in the gap of wrinkled silicon spheres, which was effectively improves the complete conductive contact and the interface compatibility between active materials. This work provides a new design strategy for preparing Si-graphite anodes suitable for commercial applications.

Integrated water quality dynamics in Wadi Hanifah: Physical, chemical, and biological perspectives.

The Wadi Hanifah, a crucial aquatic ecosystem, has unfavorable consequences from natural occurrences and human activities. Recognizing the critical need for sustainable water management, this study provides an in-depth evaluation of wadi water quality. A comprehensive assessment was conducted, analyzing physical properties (temperature, pH, electrical conductivity, turbidity, color, and odor), chemical constituents (nitrogen compounds, ion concentrations, heavy metals), and bacterial diversity. The study found significant temperature fluctuations, particularly in sun-exposed or stagnant water areas. The water exhibited slight alkalinity and variable electrical conductivity and turbidity, indicating differing pollution levels. High ammonia and heavy metal concentrations suggested organic and industrial contamination, respectively. In addition, the prevalent fecal-indicator bacteria pointed to possible sewage or agricultural runoff. The research highlights the complex interplay of natural and anthropogenic factors affecting Wadi Hanifah's water quality. It emphasizes the need for location-specific environmental management strategies focusing on pollution control and conservation to safeguard the wadi's ecological health. This study provides vital insights for effective water resource management in Wadi Hanifah, serving as a model for similar ecosystems.

Addressing salinity challenges: A comprehensive analysis of saline water and salt-tolerant soil for sustainable crop production in UC Tando Qaiser, Sindh, Pakistan

This study focuses on the physico-chemical characteristics of soils in UC Tando Qaiser, District Hyderabad, Sindh, Pakistan, irrigated by tube well water. The soil samples were collected at depths of 0-20, 20-40, and 40-60 cm, and their particle size distribution, organic matter content, pH, and salinity were analyzed. Results indicate that the soils are heavy in texture, likely influenced by the parent material deposited by the Indus River. Organic matter content was found to be low, possibly due to the absence of farmyard manure and limited cultivation of green manure crops. The majority of soils exhibit a slightly to medium alkaline reaction, characteristic of calcareous soils with high Ca2+, Mg2+, and K+ content. Slightly-saline soils were observed, emphasizing the need for soil salinity management. Tube well water analysis revealed variations in electrical conductivity, with some samples exceeding permissible limits. Recommendations include strategies to enhance organic matter, mitigate soil salinity, and implement regular monitoring of tube well water quality for sustainable agriculture in the region.

3-D simulations for maximum values of fluid distributions over separated contours on MHD peristaltic flow of pseudoplastic nanofluid in variable electric conductivity: solar applications

3-D simulations for maximum values of fluid distributions over separated contours on MHD peristaltic flow of pseudoplastic nanofluid in variable electric conductivity: solar applications

Efficient Polytelluride Anchoring for Ultralong-Life Potassium Storage: Combined Physical Barrier and Chemisorption in Nanogrid-in-Nanofiber

HighlightsThe hierarchical nanogrid-in-nanofiber-structured dual-type carbon-confined CoTe2 nanodots (CoTe2@NC@NSPCNFs) were synthesized via facile templates and an electrospinning approach.Hierarchical nanogrid-in-nanofiber structure effectively suppresses the volume change of CoTe2 and the shuttle of potassium polytelluride (K-pTex) through robust physical restraint and strong chemisorption.CoTe2@NC@NSPCNFs hybrid achieves ultralong lifespan potassium-storage performance over 3500 cycles, and the deep mechanisms underlying the evolution, dissolution, and shuttle of K-pTex have been clearly revealed.

Stochastic wave propagation in magneto-thermoelastic materials subjected to the change in electrical and thermal conductivity

This paper presents the results of an investigation that focuses on the stochastic wave propagation that occurs within an elastic medium when the thermoelectric properties are taken into consideration. It has been found that there is a clear association between the characteristics of electrical conductivity and thermal conductivity. As a result, the current topic focuses on the influence a magnetic field has on the variable thermal conductivity and electrical conductivity that exists within a material. This is done within the context of dual phase lag thermoelasticity. Several parameters are incorporated into the governing equations, which exhibit coupling. Thermal shock has been applied to the boundary of the medium that represents the non-traction barrier. At the border of the problem, stochasticity is imposed in order to make the problem appear more realistic. Within the boundary conditions, it is presumed that the white-noise function is present. Utilizing the Laplace transform method is the approach that is taken to address the issue. It is possible to determine the inverse transformations using numerical approximation approaches. Both graphical and visual analyses are performed on the dataset. In conclusion, graphical representations are utilized in order to make comparisons between the deterministic and stochastic solutions of all physical fields.

Integrating water quality monitoring and ecological assessment for wetland classification and risk evaluation in the Kirala Kele wetland, Sri Lanka

Abstract We conducted the present study to assess the spatial and temporal variations of selected physicochemical water quality parameters, to quantify the level of ecological risks of disturbances occurring, and to understand the relationship between the selected disturbances observed and physicochemical parameters of surface water of sampling sites of the Kirala Kele wetland. We selected sampling sites to reflect different land uses in the Kirala Kele wetland using purposive sampling and collected triplicated surface water samples to assess quality of water. The sampling sites of wetland characterization and risk assessment were followed using the protocol by Escom. We found that there was a significant temporal variation of pH, electrical conductivity, water temperature, and dissolved oxygen content among sampling sites (p > 0.05, One-Way ANOVA), however, spatial variation of electrical conductivity and dissolved oxygen was significantly higher in site 9, site 10, and site 11, respectively (p > 0.05, One-Way ANOVA). Site 2, site 5, site 10, and site 11 showed a category B level in wetland characterization and risk assessment highlighting the few levels of modifications and largely natural status of sites. The study demonstrates the applicability of this model for rapid assessment of wetland characteristics and risks to sustainably conserve and manage wetlands.

Estimation of the Amount of CO2 Chemically Absorbed in Real Time by Measuring the Electrical Conductivity Variation of Monoethanol-Amine Aqueous Solutions

Estimation of the Amount of CO₂ Chemically Absorbed in Real Time by Measuring the Electrical Conductivity Variation of Monoethanol-Amine Aqueous Solutions

Coupled electric circuits method applied to pulsed eddy current NDT problem

The present work concerns the study of the effect of variation of the thickness of 2D cylindrical test-piece and lift-off (the air gap between the sensor and the test-piece) on the sensor response in case of transient source current. The coupled circuit’s method employed is based on the mutual’s inductances calculation and with the association to Kirchhoff laws it yields to a transient algebraic equations system which is solved at each time step. The method is applied to the study of the pulsed eddy currents in cylindrical and axisymmetric device with electrical conductivity and geometrical dimensions variations.

Characterization of naturally occurring radioactive material dynamics in community water systems using groundwater from Ganghwa Island, Republic of Korea

Understanding the temporal behaviors of naturally occurring radioactive materials is important for the maintenance of community water supply systems for drinking groundwater on islands and in mountainous areas. Intensive field sampling in the Republic of Korea to characterize temporal variation in 238U concentration and 222Rn activity was performed for three community water systems on Ganghwa Island for ten years (2012–2022). 222Rn, a dissolved gas in groundwater, tended to decrease in activity as water moved from the source through community water systems, but no such trend was observed in 238U concentration. 238U and 222Rn behaviors in time series data for different CWSs reflected different geochemical processes and were differently classified accordingly. In particular, the 238U and 222Rn at points GJ and YH shows the signature of weathering: accompaniment by variation in pH and dissolved oxygen. In other time series, the 238U and 222Rn behavior shows the signature of cation exchange by seawater intrusion: accompaniment by dramatic variation in electrical conductivity. Random forest regression models developed to estimate the 238U concentration and 222Rn activity in groundwater boreholes exhibited reasonable threshold classification accuracy. The optimized threshold structure for 238U concentration and 222Rn activity variation with respect to the water quality variable of greatest statistical importance in each community water system random forest regression model corresponded to the geochemical process controlling the behavior of 238U and 222Rn in that groundwater borehole. Therefore, more intensive field sampling, covering the full data range that could emerge at each groundwater borehole, can aid in enhancing the accuracy of estimation of 238U concentration and 222Rn activity. Furthermore, the use of an in situ groundwater monitoring system in a random forest regression model facilitates the effective management of community water systems in the face of risk posed by naturally occurring radioactive materials.

Simultaneous Measurement of Flow Velocity and Electrical Conductivity of a Liquid Metal Using an Eddy Current Flow Meter in Combination with a Look-Up-Table Method.

The Eddy Current Flow Meter (ECFM) is a commonly employed inductive sensor for assessing the local flow rate or flow velocity of liquid metals with temperatures up to 700 ∘C. One limitation of the ECFM lies in its dependency on the magnetic Reynolds number for measured voltage signals. These signals are influenced not only by the flow velocity but also by the electrical conductivity of the liquid metal. In scenarios where temperature fluctuations are significant, leading to corresponding variations in electrical conductivity, it becomes imperative to calibrate the ECFM while concurrently monitoring temperature to discern the respective impacts of flow velocity and electrical conductivity on the acquired signals. This paper introduces a novel approach that enables the concurrent measurement of electrical conductivity and flow velocity, even in the absence of precise knowledge of the liquid metal's conductivity or temperature. This method employs a Look-Up-Table methodology. The feasibility of this measurement technique is substantiated through numerical simulations and further validated through experiments conducted on the liquid metal alloy GaInSn at room temperature.

Influence of Tectonic and Geological Structure on GIC in Southern South Island, New Zealand

AbstractAs part of a 5‐year project to assess the risk posed by geomagnetically induced currents (GIC) to the New Zealand electrical transmission network, long‐period magnetotelluric (MT) measurements have been made at 62 sites in southern South Island of New Zealand, a region where there was an absence of previous MT data. The data are largely 3‐dimensional in character, but show distinct features that can be related to the known tectonic and geological structure. In this work we focus on how the measured MT impedance tensors, and a simple interpretation of conductivity structure, can be used to assess the influence of tectonic and geological structure on GIC. We use the impedance tensors to calculate the magnitudes and orientations of induced electric fields in response to various orientations of inducing magnetic field. The electric fields so calculated are then used in a simplified model of the transmission network to calculate GIC at grounded substations. Our results confirm that tectonic/geological structure in the lower South Island and the resulting electrical conductivity variations have important impacts on the GIC magnitude. In the south‐west, smaller induced electric fields, associated with the higher conductivity in that region, lead to much reduced GIC at a substation in that area. In contrast, higher electric fields occurring in a NW‐SE band across the center of the region, contribute to much larger GIC in Dunedin city. Our results thus help explain the observed GIC reported at transformers in the region.

Numerical Investigation of the Heat Transfer and Peristaltic Flow Through a Asymmetric Channel Having Variable Viscosity and Electric Conductivity

Numerical Investigation of the Heat Transfer and Peristaltic Flow Through a Asymmetric Channel Having Variable Viscosity and Electric Conductivity

Exploring the sources of variation of electrical conductivity and total and differential somatic cell count in Italian Mediterranean buffaloes

In the buffalo dairy sector, a huge effort is still needed to improve mastitis prevention, detection, and management. Electrical conductivity (EC) and total somatic cell count (SCC) are well-known indirect indicators of mastitis. Differential somatic cell count (DSCC), which represents the proportion of neutrophils and lymphocytes on the total SCC, is instead a novel phenotype collected in the dairy cattle sector in the last lustrum. As little is known about this novel trait in dairy buffalo, in the present study we explored the nongenetic factors affecting DSCC, as well as EC and total somatic cell score (SCS), in the Italian Mediterranean buffalo. The data set used for the analysis included 14,571 test-day (TD) records of 1,501 animals from 6 herds, and climatic information of the sampling locations. The original data were filtered to exclude animals with less than 3 TD per lactation and, for the investigated traits, outliers beyond 4 standard deviations. In the statistical model we included the fixed effects of herd (6 classes), days in milk (DIM; 10 classes of 30 d, with the last being an open class until 360 d), parity (6 classes, from 1 to 6+), year-season of calving (11 classes, from summer 2019 to winter 2021/2022), year-season of sampling (9 classes, from spring 2020 to spring 2022), production level (4 classes based on quartiles of average milk yield by herd), and temperature-humidity index (THI; 4 classes based on quartiles, calculated using the average temperature and relative humidity of the 5 d before sampling). Average EC, SCS, and DSCC vary across herds. Considering DIM, greater EC values were observed at the beginning and the end of lactation; SCS was slightly lower, but DSCC was greater around the lactation peak. Increased EC, SCS, and DSCC levels with increasing parity were reported. Year-season calving and year-season sampling only slightly affected the variation of the investigated traits. Milk of high-producing buffaloes was characterized by lower EC and SCS mean values, nevertheless it had slightly greater DSCC percentages. Buffaloes grouped in the highest THI classes (classes 3 and 4) showed, on average, greater EC, SCS, and DSCC in comparison to the lower classes, especially to class 2. Results of the present study represent a preliminary as well as necessary step for the possible future inclusion of EC, SCS, or DSCC in breeding programs aimed to improve mastitis resistance in dairy buffaloes.

Formação de mudas de goiabeira irrigadas com águas de diferentes natureza catiônica e ácido salicílico

ABSTRACT The objective of this study was to evaluate gas exchange, biomass, and quality of guava seedlings as a function of the cationic nature of the water used in irrigation and foliar application of salicylic acid. The experiment was carried out in a greenhouse in Pombal, PB, Brazil, using a randomized block design, in a 6 × 4 factorial scheme with six cationic compositions of irrigation water [S1 - Control (supply water); S2 - Na+; S3 - Ca2+; S4 - Na++Ca2+; S5 - Mg2+, and S6 - Na++Ca2++Mg2+], associated with four concentrations of salicylic acid (0, 1.3, 2.6, and 3.9 mM), with 3 replicates. Plants in control (S1) were irrigated with water of electrical conductivity (ECw) of 0.3 dS m-1, while in the other treatments were irrigated with different types of water and had an ECw of 4.3 dS m-1, consisting of different cations, in the form of chloride. In the seedling formation phase, guava plants were sensitive to calcic water, which resulted in a marked decrease in their growth. Stomatal conductance, transpiration, and biomass accumulation of guava seedlings were more affected by variation in electrical conductivity than by cationic nature of the water. Salicylic acid at concentrations of 2.9 and 1.9 mM increased stomatal conductance and stem dry biomass, respectively, of guava seedlings. Water with ECw of 4.3 dS m-1 allowed the formation of guava seedlings with acceptable quality for transplanting to the field, regardless of the cationic nature of the water.

Groundwater-surface water interactions in a semi-arid irrigated agricultural valley: A hydrometric and tracer-aided approach

The purpose of this study was to assess hydrological controls (e.g., rainfall, irrigation practices, river discharge, dam operation, evaporation) on surface (SW)- ground water (GW) interactions in an irrigated valley within semi-arid Patagonia Argentina (−65.49 W, −43.29 S). We combined different sampling designs (watershed/sub-watershed scales, longitudinal and monthly samplings) from 2015 to 2019 to investigate the temporal and spatial variation of hydrometrics, electrical conductivity (EC) and stable isotope composition of surface and ground water. Results showed that plant transpiration in the upper basin, evaporation in the middle basin and the reservoir dynamics modified water salinity and left an imprint in stable isotopes. Water tables in the irrigated valley were high (0.5–2 m level from soil surface) and presented higher salinity than river water. Groundwater salinity, temporal variation of water table levels and stable isotopes suggested that groundwater is subjected to evaporation, is recharged from field seepage and, at a lesser extent, from local rainwater. River salinity increased downstream of the irrigated valley during the whole study period (3 years), showing the effects of agriculture and urbanization. EC also responded to the opening and closing of irrigation channels. EC and daily discharge statistical analysis revealed that groundwater recharge the stream below a threshold discharge of 26 m.s−1; with river salinity increasing linearly as daily discharge decrease. This study illustrates the deep modifications that agricultural systems, mainly surface irrigation, produce on semiarid watersheds. Given that SW and GW components are currently not isolated and flow regulation and irrigation practices are playing a critical role in soil quality and river chemistry at low flow conditions, a conjunctive water management strategy must be implemented in order to prevent further land and water quality degradation.

Decoupled second-order energy stable scheme for an electrohydrodynamic model with variable electrical conductivity

The motion of ions in the complex fluids widely appears in hydrodynamics, geodynamics and geophysics. Setting up suitable mathematical model, performing accurate and efficient numerical simulations are essential to understand the underlying physical principle in these phenomena. In this paper, we present a linear, second-order accurate in time, decoupled and unconditionally energy stable numerical scheme for solving an electrohydrodynamic power-law model with variable electrical conductivity. Based on a logarithm transformation for conductivity and the zero energy contribution property of the nonlinear coupling terms in the model, we derive an equivalent system by introducing a nonlocal auxiliary variable. The two-step backward differentiation scheme and the finite element method are used for the temporal and spatial discretizations, respectively. To decouple the system, the nonlocal splitting technique is employed to yield several linear subsystems, which can be solved very efficiently. Numerical simulations are carried out to demonstrate the second-order convergence in time and the unconditional energy stability. Moreover, the effects of Coulombic force and power-law fluid exponents are numerically investigated.

Structural Determinants of Redox Conduction Favor Robustness over Tunability in Microbial Cytochrome Nanowires.

Structural determinants of a 103-fold variation in electrical conductivity for helical homopolymers of tetra-, hexa-, and octa-heme cytochromes (named Omc- E, S, and Z, respectively) from Geobacter sulfurreducens are investigated with the Pathways model for electron tunneling, classical molecular dynamics, and hybrid quantum/classical molecular mechanics. Thermally averaged electronic couplings for through-space heme-to-heme electron transfer in the "nanowires" computed with density functional theory are ≤0.015 eV. Pathways analyses also indicate that couplings match within a factor of 5 for all "nanowires", but some alternative tunneling routes are found involving covalent protein backbone bonds (Omc- S and Z) or propionic acid-ligating His H-bonds on adjacent hemes (OmcZ). Reorganization energies computed from electrostatic vertical energy gaps or a version of the Marcus continuum expression parameterized on the total (donor + acceptor) solvent-accessible surface area typically agree within 20% and fall within the range 0.48-0.98 eV. Reaction free energies in all three "nanowires" are ≤|0.28| eV, even though Coulombic interactions primarily tune the site redox energies by 0.7-1.2 eV. Given the conserved energetic parameters, redox conductivity differs by < 103-fold among the cytochrome "nanowires". Redox currents do not exceed 3.0 × 10-3 pA at a physiologically relevant 0.1 V bias, with the slowest electron transfers being on a (μs) timescale much faster than typical (ms) enzymatic turnovers. Thus, the "nanowires" are proposed to be functionally robust to variations in structure that provide a habitat-customized protein interface. The 30 pA to 30 nA variation in conductivity previously reported from atomic force microscopy experiments is not intrinsic to the structures and/or does not result from the physiologically relevant redox conduction mechanism.

Aerosol-Jet-Printable Covalent Organic Framework Colloidal Inks and Temperature-Sensitive Nanocomposite Films.

With molecularly well-defined and tailorable two-dimensional structures, covalent organic frameworks (COFs) have emerged as leading material candidates for diverse applications including chemical sensing, storage, separation, and catalysis. In many of these contexts, the ability to directly and deterministically print COFs into arbitrary geometries would enable rapid optimization and deployment. However, previous attempts to print COFs have been restricted by low spatial resolution and/or post-deposition polymerization that complicates processing or limits the range of compatible COFs. Here, we overcome these limitations with a pre-synthesized, solution-processable colloidal ink that enables aerosol jet printing of COFs with micron-scale resolution. A key component of the ink formulation is the low-volatility solvent benzonitrile, which is critical to obtaining homogeneous printed COF film morphologies. The ink formulation is also compatible with other colloidal nanomaterials, thus facilitating the integration of COFs into printable nanocomposite films. As a proof-of-concept, boronate-ester COFs are integrated with carbon nanotubes (CNTs) to form printable COF-CNT nanocomposite films, in which the CNTs enhance charge transport and the temperature sensing performance of the COFs. In particular, the printed COF-CNT nanocomposite films show high in-plane COF crystallinity and exhibit tunable electrical conductivity as a function of CNT loading, COF pore size, and temperature, ultimately resulting in high-sensitivity temperature sensors that show electrical conductivity variation by 4 orders of magnitude between room temperature and 300°C. Overall, this work establishes a flexible platform for COF additive manufacturing that can accelerate the incorporation of COFs into technologically significant applications. This article is protected by copyright. All rights reserved.