Horizontal Electrodes Research Articles

Three-dimensional forward modeling and quantitative assessment of electrode offset effects in ERT

Resistivity data has important applications in geophysical exploration, but the impact of electrode offsets on resistivity response characteristics remains unclear. This study aims to explore the influence of horizontal electrode offset angles and vertical offsets caused by topographical variations on the forward modeling of resistivity data. By analyzing experimental models with different measurement arrays, the paper revealed their influence laws on the buried depth of the target body and resistivity resolution. Utilizing tools like ZondRes3D, we conducted 3D resistivity forward modeling and analyzed the results in detail. It is found that horizontal electrode offsets lead to pseudo-anomalies in the apparent resistivity response, which is related to the offset angles and the number of electrodes. Under different conditions, the horizontal electrode offsets exhibit a “gradient variation” pattern. In addition, topographical variations can also cause distortions and offsets in the apparent resistivity curves and the locations of the anomaly response. Specifically, the measuring lines near the edge of the target bodies are more susceptible to these effects. Based on the comprehensive experimental results, we have drawn several conclusions regarding the impact of electrode offsets and topographical variations, including the effects of offset angles on the pseudo-anomalies, the anomalous response laws under different topographic conditions, as well as anomalous situations under specific angles. These findings provide crucial insights for interpreting resistivity data in geophysical exploration and addressing practical engineering problems, and offer guidance for optimizing measuring line layouts and post-processing terrain correction algorithms.

Effect of soil layering and interface resistance on electro‐osmotic consolidation of layered soils: A Green's function approach

AbstractDuring electro‐osmotic consolidation, effective voltage attenuation induced by the increasing interface resistance is an important phenomenon, which significantly decreases consolidation effectiveness. This paper presents an analytical model for one‐dimensional electro‐osmotic consolidation in layered soils with horizontal graphite electrodes considering effective voltage attenuation. The mathematical model is characterized by time‐dependent source term and discontinuous interface flux. New variables are introduced to homogenize the discontinuous interface flux and Green’s function method is used to solve the new nonhomogeneous governing equations with nonhomogeneous boundaries. Several verification examples are conducted using the existing analytical solution and numerical results. Parametric studies indicate that electro‐osmotic consolidation of layered soils cannot be accurately simulated by equivalent homogeneous soil, whether effective voltage attenuation is considered or not. Furthermore, the backflow phenomenon may occur due to effective voltage attenuation, while it may disappear when the anode is placed in the low‐permeability layer. In addition, the optimal arrangement of electrodes in layered soils is also investigated. When the ratio of the thickness of low‐permeability layer to high‐permeability layer is about 1/3, installing the cathode in the low‐permeability layer can improve the electro‐osmosis effect up to two times, compared with installing the anode in the low‐permeability layer.

Semi-analytical solution for one-dimensional coupling consolidation of original soil and electro-osmotic layer using horizontal electrodes

The application of horizontal electro-kinetic geosynthetics for electro-osmotic consolidation is becoming increasingly widespread. Such horizontal electrodes are typically arranged at intervals, allowing pore water in original soil to pass through the intervals and penetrate into the electro-osmotic layer. In this study, a one-dimensional semi-analytical solution for a double-layered electro-osmotic system incorporating the original soil was presented and verified. The effects of the soil properties on the consolidation process were investigated. Results revealed that original soil can achieve a significant consolidation effect, even better than electro-osmotic dredged soil. A smaller permeability coefficient of original soil significantly prolongs the consolidation time, while a thicker original soil can improve the average consolidation effect of the two layers. The proposed model provides new electrode arrangement ideas and theoretical support for horizontal electro-kinetic geosynthetics for electro-osmotic reinforcement.

Novel Fe-Ti nanoparticles synthesized in deep eutectic solvents for enhanced photo-electro-Fenton processes: Synergistic effects and environmental applications

An innovative titanium-magnetite (Fe-Ti) catalyst was developed using a production strategy based on water-free solvents such as deep eutectic solvents (DES) for the removal of persistent pollutants. The prepared catalyst was applied in electro-Fenton and photo-electro-Fenton processes. To this end, a new cell design with electrodes based on conductive materials was developed using 3D printing in two different electrochemical cells configurations: vertical electrode configuration (VEC) and horizontal electrode configuration (HEC). The HEC showed good performance attaining a yield hydrogen peroxide production of 20 mg·L−1 and being able to operate in electro-Fenton degradation batch assays for the removal of the drugs (Antipyrine and Lissamine Green B). Then, the heterogeneous bimetallic catalyst (BC-FeTi) was tested and compared with the monometallic Fe catalyst (MC-Fe). The results with both catalysts showed a synergistic effect combining electrochemical oxidation and Fenton reaction, promoting the best removal of the target pollutants. Subsequently, the contribution of UV radiation was evaluated with BC-FeTi, achieving that more than 80 % of both pollutants were removed in 80 min by the photo-Fenton process, confirming the high affinity of oxidizing free radicals for high molecular weight organic molecules. Finally, the simultaneous application of electro- and photo-oxidation (photo-electro-Fenton) significantly improved the removal of the target contaminants from the aqueous solution, achieving complete removal in 50 and 80 min for Lissamine Green B and Antipyrine, respectively. The stability and reusability of BC-FeTi and 3D-printed electrodes were achieved in five successive working cycles, with negligible loss of activity compared to new catalysts, which achieved greater than 99 % removal after five consecutive runs. Leaching of iron and titanium from the catalyst evaluated throughout the cycles, was low, totalling 2.7 and 4.5 % at the end of the fifth cycle.

Insights into dynamic switching behavior and electric field distribution of depletion-mode GaN HEMT with bonding pad over active layout

Bonding pad over active (BPOA) layout, which stacks traditional horizontal structure pad electrodes vertically above the active area, is an area-effective device architecture and packaging-enabled solution for GaN-based high electron mobility transistors (HEMTs). In this work, the dynamic switching and electric field distribution of such layout, as well as associated capacitance–voltage and trapping characteristics, are comprehensively studied on D-mode GaN-on-sapphire HEMT by performing numerical simulations. In terms of different pad electrodes covering the active area, BPOA is composed of various structures such as gate-related and drain-related BPOAs (i.e. G-BPOA and D-BPOA), among which G-BPOA exhibits inferior switching characteristics due to the additional introduction of Miller capacitance that prolongs the device switching, while breakdown voltage of D-BPOA is 400–900 V lower than other BPOA counterparts due to the interplay between D-BPOA and the drain electrode. Furthermore, the effects of trap capture cross section and trap density on switching characteristics are evaluated. These results highlight the differences in electrical characteristics of various structures within the BPOA layout, and provide valuable insights into BPOA device design and performance improvement.

The influence of flow electrode channel design on flow capacitive deionization performance: Experimental and CFD modelling insights

Flow capacitive deionization (FCDI) is an emerging desalination technology at which flow electrodes (shear-thinning flowable carbon slurries) are used to remove ions from saline water. The geometry of flow electrode channels, which provide the path and ensure the distribution and mixing of the flow electrodes, is one of the most important aspects to be optimized. This work presents experimental and computational fluid dynamics (CFD) modelling analysis of the influence of the geometry of flow electrode channels on FCDI performance. Flow electrode gaskets (with open, serpentine (short) horizontal and serpentine (long) vertical channels) were 3D printed using a polyethylene terephthalate glycol (PET-G) filament. The FCDI cell with a vertical serpentine flow electrode channel exhibited the poorest performance due to channel blockage by carbon particles, while the best results were achieved with a horizontal serpentine flow electrode channel. CFD simulations aided in understanding this behaviour by showing that the channel geometry strongly affects the local shear rate, and thus the local viscosity of flow electrodes. Thus, it is recommended to design channels that induce flow disturbance aiming for increasing the shear rate and hence reducing flow electrode viscosity, therefore promoting their flowability and reducing clogging chances.

Analytical models for electroosmotic consolidation of layered soil systems considering the boundary effects of horizontal electrodes

AbstractThe pore water can usually flow through the horizontal electrodes, resulting in the top sand layer and the bottom unelectroosmotic layer inevitably affecting the consolidation process of the electroosmotic layer. However, the traditional assumption of the fully drained or undrained electrode boundaries is unable to reflect these boundary effects. In this study, one‐dimensional analytical models for electroosmotic consolidation of the layered soil systems considering the boundary effects of horizontal electrodes are proposed. The solutions for the models are derived using the separate variable method and Laplace transform method. The rationality of the one‐dimensional model is also illustrated by comparing it with the results produced by the two‐dimensional model and the accuracies of the solutions are verified through a series of analytical and numerical validation examples. Parametric studies are conducted to investigate the effects of the sand layer and the unelectroosmotic layer on the consolidation process. Results show that both the sand layer and the unelectroosmotic layer may significantly delay the consolidation progress. The time factor corresponding to 90% average degree of consolidation (Tv_90%U*) can increase by over 1.5 times in comparison with the model without a sand layer when the permeability coefficient ratio of the subsoil to the upper layer reaches 10. The delayed effect is particularly pronounced when the thickness of the unelectroosmotic layer with higher compressibility is relatively larger, potentially resulting in a tenfold or even greater increase in Tv_90%U*.

Analysis of grounding system transient with consideration of soil ionization and mutual coupling effect

The grounding system of an electrical substation provides safety to both operator and equipment. The lightning current waveform has a major influence on the dynamic performance of ground electrodes. If lightning current is large enough, soil will be ionized, which will have a great effect on the transient performance of the grounding system. Many numerical models have been developed to evaluate the transient performance of grounding system, still it is a challenging task to analyze the impulse behavior of grounding system efficiently. In this paper, the transient behavior of grounding systems with consideration of nonlinear and dynamic effects of soil ionization is presented. Grounding systems such as vertical rod, horizontal conductor and grounding grid buried in the homogeneous soil are considered as case study. Proposed model is the combination of circuit theory approach and method of moment with consideration of frequency-dependent impedance and mutual coupling effect between the conductor segments. Self and mutual component of inductance and resistance are considered in the analysis. Initially, transient performance of grounding system is analyzed for single vertical rod, horizontal and square grounding electrodes, further it is extended for vertical rod (more than one), horizontal conductor and grounding grids with different configurations. The analysis of grounding system with the consideration of mutual coupling effect is compared with devoid of mutual coupling, and differences between them are evaluated. For validating the developed method, simulated results are compared with the results reported in the literature, and good agreements are found. Analysis shows that the grounding impulse impedance decreased with increasing the magnitude of injected current. Developed method will help to improve the modeling of simple as well as complex grounding system buried in homogeneous soil.

Enhancing Tank Leaching Efficiency through Electrokinetic Remediation: A Laboratory and Numerical Modeling Study

Electrokinetic remediation is a cost-effective and efficient method that utilizes electrical current to transport ions within the subsurface. This process aims to remediate soil contamination caused by industrial activities, which poses threats to wildlife, water quality, and air quality. To assess the impact of the electrokinetic process on tank leaching efficiency, two electrode configurations were tested: vertical and horizontal arrays. These tests considered variable electrode spacing and different voltages in the soil residue. Additionally, the movement of copper cations from the anode to the cathode under this process was investigated. Results show that the horizontal electrode array is more effective in transporting soil moisture because of its broader contact with the soil. After 20 days of using the electrokinetic method with vertical electrodes, the soil moisture content decreased by 12.28%; with horizontal electrodes, it dropped by 38.4%. Also, the concentration of copper in the soil near the cathode electrode increased from 0.54 to 0.77% after 20 days. The estimated copper ion content in the cathode area after 20 days was between 150 and 350 mol/m3, aligning closely with the measured value of 192.5 mol/m3. These results indicate that the electrokinetic process can significantly enhance copper recovery efficiency in tank leaching processes and curtail environmental side effects. Overall, this study provides valuable insights into the benefits of using the electrokinetic process to remediate leaching residue and improve the efficiency of industrial processes.

Wire electrochemical contour evolution machining of gear involute artifact with horizontal electrode

Wire electrochemical contour evolution machining of gear involute artifact with horizontal electrode

Electrodynamic suspension of particles with finite electrical conductivity

The electrodynamic suspension of micrometric inertialess particles with finite electrical conductivity in the gap between two parallel horizontal electrodes subjected to a DC potential difference is analyzed in a collision-dominated regime in which the mean free path between particle collisions is small compared with the interelectrode distance. Operation with a constant number of suspended particles and with an excess of particles deposited on the lower electrode are modelled. Stationary solutions in a laterally unbounded gap are computed and their linear stability is analyzed. In both cases, these solutions become unstable when the number of suspended particles increases, and they transition to time dependent solutions. Numerical computations show that particle and charge accumulations develop at the lower electrode and eventually become electrohydrodynamic plumes rising across the gap. The electric current carried by the suspended particles from the lower to the upper electrode is a rapidly increasing function of the particle conductivity.

The RBF-FD and RBF-FDTD Methods for Solving Time-Domain Electrical Transient Problems in Power Systems

In this paper, the development and application of the radial basis function-finite difference (RBF-FD) method and the RBF-finite difference time domain (RBF-FDTD) method for solving electrical transient problems in power systems that are defined by the time-dependent ordinary differential equations (ODEs) and the time-dependent partial differential equations (PDEs), respectively, are presented. RBFs such as Gaussian (GA), Multiquadric (MQ), Inverse Quadric (IQ), and Inverse Multiquadric (IMQ) are used in these numerical methods to formulate the central finite difference approximations of the first- and second-order derivatives of a function. The algorithm of selecting “optimal” shape parameters for our basis functions is also applied, specifically to increase the accuracy of the suggested methods with regard to high accuracy needs. Finally, the accuracy, effectiveness, and applicability of our new approaches are evaluated through simulations of the switching transient voltages on a typical electrical circuit and a 220 kV single-phase transmission line, lightning-induced voltages on a 110 kV single-phase overhead distribution line, and transient voltages along two horizontal grounding electrodes excited by lightning impulse sources. The obtained numerical results demonstrate that our proposed RBF-based numerical approaches compare favorably to the traditional numerical methods.

Neuromorphic System Using Memcapacitors and Autonomous Local Learning.

Artificial intelligence is used for various applications and is promising as an indispensable infrastructure in future societies. Neural networks are representative technologies that imitate human brains and exhibit various advantages. However, the size is bulky, the power is huge, and some advantages are not demonstrated because they are executed on Neumann-type computers. Neuromorphic systems are biomimetic systems from the hardware level to implement neuron and synapse elements, and the size is compact, the power is low, and the operation is robust. However, because the conventional ones are not composed of fully optimized hardware, the power is not yet minimal, and extra control circuits must be used. In this article, we developed a neuromorphic system using memcapacitors and autonomous local learning. By using memcapacitors, the power can be minimal, and by using autonomous local learning, the control circuits to handle the synapse elements can be deleted. First, the memcapacitors are completed in a cross-bar array, where the ferroelectric layers are sandwiched between the horizontal and perpendicular electrodes. The polarization and capacitance exhibit hysteresis due to the dielectric polarization. Next, autonomous local learning is introduced as follows. During the training phase, associative patterns to be memorized are directly sent, relatively high voltages are applied, and dielectric polarizations are induced. During the operation phase, relatively low voltages are applied, and input signals are weighted with the capacitances of the memcapacitors, summed, and transferred as the output signals. Finally, the experimental system is set up, and the experimental results are acquired. The memorized patterns during the training phase, distorted patterns as the input signals during the operation phase, and retrieved patterns as the output signals in the operation phase are shown. Researchers found that the retrieved patterns are completely the same as the memorized patterns. This means that the neuromorphic system works as an associative memory.

Modeling and performance analysis of electrostatic desalter using combined CFD-PBM method

In this research, a combined method of computational fluid dynamics and population balance model were used to simulate the electrostatic desalter units using the ANSYS Fluent software. The goal of this study is to investigate the effective parameters in separating brine from oil and optimizing the desalter performance. The model was subjected to sensitivity analysis for four parameters: temperature, wash water percentage, inlet distributor, and electrodes arrangements. The results showed that raising the temperature up to 130 °C and increasing the wash water percentage improved the separation. Also, the separation is greatly improved by switching to a T-shaped input distributor. The separation is not considerably affected by the number of horizontal electrodes, while the vertical electrodes have a negative impact. Finally, sensitivity analysis was performed on an existing desalter located in one of the Iran’s oil fields. The findings demonstrated that the current situation does not meet the acceptable limit of 0.3% vol of brine in the oil outlet. The desalter outlet meet the specifications by switching the type of distributor to a T-shaped one, and additionally when the temperature is 90 °C and 10% wash water or 100 °C and 8.3% wash water without changing the geometry.

Method of Line for Modeling of Grounding Electrodes Buried in Stratified Multilayer Soil

An efficient full-wave semi-analytical method based on the method of line is developed for rigorous modeling of grounding electrodes buried in stratified multilayer soil. As compared to the existing full-wave modeling techniques, the proposed method is extremely computationally efficient while enables modeling of any number of vertical and/or horizontal soil layers. Furthermore, the proposed method is not prone to any stability or convergence numerical issue. The efficiency and accuracy of the proposed method is evaluated using the cases of horizontal and vertical grounding electrodes buried in vertically or horizontally stratified multilayer soil.

Low-hysteresis, pressure-insensitive, and transparent capacitive strain sensor for human activity monitoring

Wearable strain sensors have been widely used for human activity monitoring. Most reported strain sensors have mainly focused on material engineering, high stretchability and large gauge factors. Few works have focused on strain sensor’s robustness and reliability, including low hysteresis, good long-term stability, good electrode material stability, and low coupling effects under multi-input signals, which are the factors that limit practical strain sensor applications. To develop a high-performance strain sensor, we propose a flexible capacitive sensor structure with three-dimensional (3D) interdigital electrodes fabricated by vertically aligned carbon nanotubes. Compared with a traditional resistive strain sensor and a capacitive strain sensor with vertical sandwich electrodes, a strain sensor with horizontal parallel interdigital electrodes can benefit from low cross talk in terms of the normal force and improve substrate transparency. Additionally, embedding 3D electrodes into the substrate improves ultrahigh robustness with a low-pressure coupling effect under normal force. Moreover, compared with other reported works, the electrode variation under strain is small (less than 1.6%), which means that the perturbation of inert properties on device performance is small. Finally, the fabricated strain sensor achieves an ultralow hysteresis (0.35%), excellent pressure-insensitive performance (less than 0.8%), fast response (60 ms), good long-term stability, and good transparency. As an application example, a flexible strain sensor was successfully demonstrated as a wearable device for the precise monitoring of different types of human activities, including bending of the finger, knee, elbow, wrist, and neck with large strain signals and small strain signals generated by a mouth-opening activity. This excellent performance indicates that the flexible strain sensor is a promising candidate for human motion detection, soft robotics, and medical care.

Nanometer-sized etching of lithium niobate domain wall devices

Ferroelectric LiNbO3 single crystals have piezoelectric, pyroelectric and electro-optic properties and are widely used in nonvolatile memories, sensors, and electro-optic modulators. The material is hard and relatively inert for dying etching using thick Cr/Ni mask layers which are incompatible with the CMOS manufacturing technologies. Moreover, the etching angles are generally below 80° that could result in poor polarization retention and a large imprint effect. Here we developed an etching technique on the basis of the solid-state reaction and wet solution corrosion together that used CMOS-compatible SiO2 masks to fabricate large arrays of LiNbO3 nanodevices in high precision. The LiNbO3 nanopatterns at the regions beyond the SiO2 masks can react with the deposited Al metal below 500 °C in formation of amorphous layers in targeted thicknesses that vary with the annealing temperature and time at a reduced atmosphere. The amorphous layers can be dissolved in mixed solutions of H2O, NH4OH, and H2O2 at 85 °C, and the etching angles of memory cells in lateral sizes of 20–220 nm can approach 90° after the passivation of the LiNbO3 surface layer. The transmission electron microscope study shows the oxygen deficiency at the surface. After the connection of the cell to two side electrodes, domain switching occurs under an applied horizontal electrode field along the polar Z-axis accompanying the formation of conducting domain walls against the peripheral unswitched domain at the substrate. The read current can highly reach the level of 2–20 μA in high reliability. This etching technique promotes the large-scale fabrication of LiNbO3 nanodevices on the Si platform.

Lightning Performance of Multiple Horizontal, Vertical and Inclined Grounding Electrodes

Single horizontal and vertical grounding electrodes are often used for an earth connection of the lightning protection system. However, there are many practical situations when such electrodes have to be enhanced for better efficiency and replaced by multiple horizontal, vertical and/or inclined electrodes. This paper presents a systematic approach to evaluating and comparing the lightning performance of such grounding arrangements based on simple formulas. The contributions of this paper are: It is shown that impulse impedance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i> may be derived from known formulas for low-frequency grounding resistance <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> ; a new definition of effective length is introduced that allows for such a derivation; a collection of accurate formulas for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> of all considered grounding electrode arrangements is presented; and a new concept of “effective volume” is described that enables a simple procedure to increase electrodes’ effective length. The new formulas for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> , <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i> , and effective length of the different electrode arrangements allow an analysis that might help search for a choice of cost-effective configuration and dimensions of the grounding systems in the early design stage.

БИОЭЛЕКТРОГЕНЕЗ МИКРОБНЫХ ТОПЛИВНЫХ ЭЛЕМЕНТОВ В ПРИСУТСТВИИ SHEWANELLA ONEIDENSIS MR-1 И НЕКОТОРЫХ ТЯЖЕЛЫХ МЕТАЛЛОВ

The high anthropogenic load on the environment makes it necessary to develop new ways of cleaning the environment. One of the promising methods in remediation processes is the use of living organisms. So, for almost every pollutant, it is possible to select the appropriate strain of microorganisms capable of decomposing certain pollutants. The study used benthic-type microbial fuel cells as promising bioengineering systems that can be applied in various areas of human life - medicine, cleaning and environmental monitoring, in the Internet of Things, etc. In addition, the electrogenic potential created by MFC will facilitate the migration of heavy metals towards the anode, which will simplify the process of their removal from the environment or inclusion in the food chains of anodophilic microbiota. As a result of the study, it was found that the most effective in the design of the MFC are horizontal electrodes. Also, pollutants eventually begin to have a negative impact on the bioelectrogenesis of microbial fuel cells and, accordingly, on the local microbiota.

Enhancing directivity of terahertz photoconductive antennas using spoof surface plasmon structure

Terahertz photoconductive antenna (PCA) is an important device for generating ultrabroadband terahertz radiations, being applicable in various scenarios. However, the metallic electrodes in PCAs, a pair of coplanar strip lines (CSL), always produce horizontal electrode modes in a broad THz band, thus resulting in low directivity in the vertical direction. Here, we introduce spoof surface plasmon polariton (SSPP) structures to suppress horizontal electrode modes in a broad band. The suppression principles are accounted to both the forbidden band of the fundamental SSPP mode and the orthogonality between source and higher-order SSPP modes. In the SSPP-modified PCA, we achieve around 2 dBi higher directivity in the vertical direction compared to a typical CSL PCA. Unlike the narrow bands inheriting from conventional metamaterial resonators, the relative operational band of the SSPP-modified PCA is as broad as 48%. This planar SSPP structure is compatible with the well-developed micro fabrication technologies. Thus, our scheme can be combined with the semiconductor material engineering and plasmonic nanoscale structures for further increasing THz output power.