Low Resistivity Values Research Articles

Evaluation of the possibility of searching for groundwater using electrical resistivity tomography based on the data of numerical modelling in complicated permafrost conditions (the case of the territory in the eastern part of the Republic of Buryatia)

Relevance. Groundwater is the main source of industrial and technical water supply for mining facilities. The geological structure of the studied areas can be complicated by various factors that make it difficult to search for and localize groundwater. In this regard, electrical geophysical prospecting methods are often included in the complex of prospecting and exploration works, before which it is necessary to justify the application of the chosen method for solving the problems by performing numerical modelling. Aim. To substantiate the use of electrical resistivity tomography for the search for groundwater, taking into account complicating factors, including perennially frozen rocks, taliks, and fault zone, by numerical modelling. Objects. Geological environment represented by Quaternary system rocks and permafrost rocks of Cretaceous sediments of the Zazinskaya intermontane area, fault zone, talik zones. Methods. Solution of the direct problem, solution of the inverse problem, ground geophysical surveys using electrical resistivity tomography. Results. Based on the performed numerical modelling, it is shown that the use of electrical resistivity tomography is expedient when searching for groundwater in the area characterized by various factors: permafrost, talik, and a fault zone. Based on the results of solving direct and inverse problems of electrical survey, using field works performed in 2020 in the Eravninsky district of the Republic of Buryatia as an example, it is shown that pole-dipole arrays in electric resistivity survey with electrode distance of 5 m, successfully confirmed by drilling operations, allow us reliably delineate potential zones of water inflow. These zones, characterized by low values of electrical resistivity, in this area, are related to talik zones, which are powered by heat flow from the bowels of the earth.

The Result of Electrical Resistivity Investigation of Solid Waste Landfill Conducted at Nsukka Municipality Using Electrical Resistivity Measurments

Solid waste landfill management has been a significant issue for Nigerian urban areas and other developing countries across the globe.Similar to most other cities, Nsukka also generates waste on a daily basis, much of which is dumped in poorly designed and positioned dumping sites. The majority of the disposal sites are found on roadsides, at marketplaces, on farms, and in residential neighborhoods, among other places. The road infrastructure and groundwater are under danger, and the beauty of the impacted communities are not spared. Undoubtedly, the unchecked citation of boreholes as the source of potable water in the majority of our rural and urban communities—given that the government doesn't seem to be providing water to the people—has become a significant challenge. An investigation using electrical resistivity method was conducted around a solid waste dumpsite at Nsukka in Nsukka L.G.A of Enugu State, Nigeria with an aim to investigate the level of groundwater contamination and the objectives to determine the subsurface geoelectric layers, depth to water table, lithology delineation and map out the contamination zones. The scope of this study provides an overview of some of the approaches used to assess the aquifer vulnerability and aquifer potential using Vertical Electrical Sounding (Schlumberger array) and 2D resistivity imaging (Wenner array) in different locations around Nsukka municipality dumpsite. Both methods were used for this study in order to provide a geophysical database for exploration of the study area’s groundwater resources and also they are less expensive and less time consuming. VES has proved to be effective in solving groundwater problems in most places in Nigeria (Ezeh and Ugwu, 2010; Ugwu and Ezeh, 2012; Nzemeka et al. [1,2]. Electrical Sounding (VES) and 2D resistivity imaging were carried out with a digital read out resistivity meter (ABEM SAS 1000) to acquire data in the area and were interpreted using the Schlumberger automatic INTERPEX analysis software and the RES2DINV software respectively, which generates model curves using initial layer parameters and display the variations of electrical resistivities respectively. A total of eight (8) sounding and six (6) 2D resistivity imagings were carried out in the area. A contaminant leachate plume was delineated in 2D resistivity sections as low resistivity zones while the VES shows the depth of aquifer. In 2D pseudosections where bluish colours with low resistivities (less than 20.80\(\Omega\)m) with the depth ranging from 1.28m to 17.1m in the Line 1 and 2 are seen as contaminated zones. The rest of the lines are not contaminated because of their high resistivities (greater than 20.80\(\Omega\)m). The result of the electrical resistivity survey also showed 4 - 5 layers geo-electric sections and an AA and AK type sounding curves. The VES result shows that VES 1A, 1B, 2A and 2B which are carried out on line 1 & 2 of the wenner lines showed signs of contamination with low resistivity values less than 20.80\(\Omega\)m complementing the wenner results. The contamination has not yet got to where the aquifer is located on the lines. Since the depth to the aquifer ranges from 30.26m to 155.43m while maximum depth of contamination is 17.1m. It is believed that the leachate has not percolated down to the aquiferous zones as such aquifers are presumed to be free. As such, it is recommended that boreholes around the study area should not be less than 30m deep to avoid exploiting polluted water.

Activated carbon derived from corncob via hydrothermal carbonization as a promising electrode for supercapacitors

Activated carbon has been synthesized from corncob via hydrothermal treatment at 200 °C for 7 h with and without activating agents, followed by carbonization at 400 °C for 3 h. The X-ray diffraction patterns show peaks corresponding to the amorphous and graphitic carbon phases. The SEM studies reveal meso and macro pores. The H3PO4 treated sample (CC-H-400) shows the highest Brunauer-Emmett-Teller surface area (68.54 m2 g-1). Raman spectra indicate the typical D and G bands. The CC-H-400 shows the highest specific capacitance value of 41 F g-1 among all the samples. The energy and power density values of the supercapacitor working electrode in a three-electrode setup are 5.7 W h kg-1 and 500.4 W kg-1, respectively, for the CC-H-400. Furthermore, the CC-H-400 exhibits excellent stability with a retention rate of 88 % after 2000 charge-discharge cycles at 10 A g-1 without any shape change, as well as a low equivalence series resistance (ESR) value of 3.96 Ω.

Assessment and development of empirical correlations between flat plate dilatometer and cone penetration tests for Auckland soils

ABSTRACT Based on a database of over 2900 cone penetration test (CPT) and flat plate dilatometer test (DMT) data pairs obtained from Auckland, New Zealand, this paper assesses the applicability of several empirical CPT-DMT correlations and presents newly developed regional correlations for use in geotechnical engineering applications. Empirical correlations using the DMT-based material index are assessed. As both the DMT-based material index (ID ) and the soil behaviour type index (Ic ) from CPT data are often used to estimate soil behaviour characteristics when no samples are retrieved, these were used to develop subset databases. In general, the correlation used to estimate the material index (ID ) tended to slightly overestimate the measured values for Auckland soils, while better performance could be observed after removing data points where Ic and ID soil classifications were incompatible. In contrast, the correlations used to estimate horizontal stress index (KD ), and dilatometer modulus (ED ) underestimated the measured values for the database used herein, with the largest underestimates for low cone tip resistance values. This paper presents new correlations for estimating KD and ED based on CPT parameters for Auckland soils, providing improved estimates, with stable bias values across the range of input parameters considered.

The figure of merit improvement of (Sn, Co)–ZnO sprayed thin films for optoelectronic applications

Nanocrystalline zinc oxide (ZnO) has garnered significant attention from researchers and industries due to its superior properties as an optoelectronic material, particularly in solar cells as a transparent electrode. Doping, especially with tin (Sn) and co-doping with tin and cobalt (Co), can refine its optoelectronic properties. In this manuscript, we report on the optoelectronic properties of undoped ZnO thin films, as well as those doped with Sn and/or Co, elaborated using a simple chemical pneumatic spray pyrolysis method on glass substrates. A 1 % Sn doping concentration was used, with Co doping concentrations of 0 %, 0.5 %, and 1 %. The effects of Sn and/or Co doping concentration on the structure, morphology, optical, and electrical properties of nanocrystalline ZnO were studied using X-ray diffractometer (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FESEM), UV–Vis–NIR spectroscopy and Hall effect measurements. All the films studied exhibit wurtzite ZnO structures with a predominant (002) orientation and no secondary phase, as confirmed by X-ray diffraction (XRD) analysis. The Raman spectroscopy also reveals the presence of a wurtzite structure in all the films. The FESEM images reveal the kind and concentration of the dopants significantly influenced the surface morphology of the films. The elemental analysis with energy dispersive X-ray analysis (EDS) analysis successfully detected the doping of Sn and Co. The analysis of UV–Vis spectroscopy provide that the optical band gap for the undoped ZnO film is 3.25 eV. This band gap increases upon doping and co-doping, reaching a peak value of 3.30 eV for the Sn:Co (1 %:0.5 %) co-doped ZnO film. The ZnO film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 1.95 × 10−2 Ω cm for the film (1%Sn, 0.5 % Co)–ZnO. The highest figure of merit (FOM) achieved is 1.41 × 10−4 Ω−1 for a ZnO thin film co-doped with (1 % Sn, 0.5 % Co). The existence of (1 % Sn, 0.5 % Co) film with improved optical gap, low electrical resistivity and high FOM supports its use in transparent conductive oxide applications.

Evaluation of the backflashover performance of 150 kV and 400 kV double-circuit overhead transmission lines as affected by lightning attachment models and peak current distributions

The evaluation of the backflashover performance of overhead transmission lines requires the adoption of a lightning attachment model and a peak current distribution. These affect the estimated backflashover rate, BFR, of the lines. The present study aims to quantify the influence of lightning attachment model and peak current distribution on the BFR of double-circuit overhead lines. This is achieved by evaluating typical 150 kV and 400 kV lines. ATP-EMTP simulations are conducted to obtain the critical currents causing backflashover of line insulation. Then, the critical currents are used in lightning incidence computations to obtain BFR. The influencing parameters taken into account in this work are the low current and low frequency tower ground resistance, the location of lightning strike to the shield wire along the span, and the AC voltage phase angle, all affecting the critical backflashover current. Several lightning attachment models and peak current distributions are evaluated. Their influence on BFR is found to be considerable, especially for lower tower ground resistance values. The lightning peak current distributions yield more pronounced effects on BFR. The results of this study stress the need for computing BFR using a more accurate expression than the simplified one based on CIGRE TB 63.

Influence of Apparatus Scale on Geogrid Monotonic and Cyclic/Post-Cyclic Pullout Behavior in Cohesive Soils

Geosynthetics have increasingly been applied to geotechnical engineering works due to their numerous advantages, including cost-effectiveness and their significant role in sustainable development. When geosynthetics are used as reinforcement in earth structures, such as embankments, retaining walls and bridge abutments, soil–geosynthetic interface shear behavior is a critical parameter involved in the design. This paper presents a series of monotonic and cyclic/post-cyclic pullout tests carried out to examine the apparatus scale effect on the pullout response of a geogrid embedded in two different soils. To assess the small-scale equipment feasibility, comparisons were made between pullout test parameters derived from small- and large-scale equipment. The test results indicate that, under a low confining stress of 25 kPa, using a smaller-sized apparatus results in lower values of geogrid pullout resistance and maximum mobilized shear stress, but higher values of confined tensile stiffness at low strains. On the other hand, as the confining stress increases (i.e., 50 kPa and 100 kPa), the difference between the results becomes less significant and similar trends are observed regardless of the equipment type. Adopting small-scale equipment enables obtaining soil–reinforcement interaction parameters using test procedures that are less time-consuming than those associated with large-scale pullout tests. However, proper scale effect correction factors may be considered for more consistent estimates of the interface strength parameters under low normal stress values.

ZnO nanoarrays/Cu nanowires composite films with high haze value

In this work, we worked on compositing Cu nanowires (NWs) with ZnO nanoarrays (NAs) to enhance the light trapping abilities of transparent conductive films. A well-dispersed, crosslinked network of Cu NWs with appropriate light trapping ability was formed on the surface of the ZnO NAs, and the ZnO NAs/Cu NWs composite structures were obtained ultimately. The Cu NWs on the surface of the composite structures maintained excellent transparency and conductivity while preventing agglomeration phenomena. The ZnO NAs/Cu NWs composite films exhibited low average sheet resistance (59 Ω/sq) and high haze value (0.53) at 550 nm with uniform conductivity and exceptional light trapping performance. The composite films not only demonstrate enhanced light trapping abilities, but also exhibit improved electrical properties, making it an outstanding candidate for transparent front electrode materials in solar cell applications.

Harnessing the synergistic effects of graphene oxide based Sn/Fe codoped Bi2O3 nanocomposites for superior supercapacitor performance

Pure Bi2O3, 5 % Sn/Fe codoped Bi2O3, Graphene Oxide (GO) based Pure, and 5 % Sn/Fe codoped Bi2O3 nanocomposite are synthesized using a hydrothermal method. The synthesized material is comprehensively characterized to investigate its crystallographic, morphological, magnetic, and surface properties. Our findings reveal that the GO-based 5 % Sn/Fe co-doped Bi2O3 exhibits an exceptional capacitance of 1302.5 F/g. This remarkable capacitance enhancement can be attributed to a combination of factors, including changes in crystalline size, enhanced magnetization properties, an increase in surface area (170.86 m2/g), the introduction of defects in the material's structure, as well as low value of charge transfer resistance (0.3817 Ω) which indicates exceptional conductivity of the material. GO-based 5 % Sn/Fe co-doped Bi2O3 illustrates remarkable cycle stability with a retention rate of 81 % after 2000 cycles. The findings from this research provide evidence that GO-based Sn/Fe co-doped Bi2O3 is a material with outstanding prospects for high-performance energy storage applications, especially in supercapacitors. The combined effects of GO inclusion and co-doping provide new opportunities for the development of novel electrode materials with improved electrochemical characteristics.

Optimizing bimetallic-insect exuviate melanin composite cathodes using response surface methodology to enhance the H2O2 yield and selectivity of the electro-Fenton process

Electro-Fenton is a fast and efficient oxidative degradation technology for treating many refractory organic substances. However, the poor electrochemical performance and power generation capacity of the cathode during electro-Fenton treatment limit H2O2 generation and pollutant removal. A FeCu bimetal–melanin cathode catalyst with high H2O2 production, low Fe3+ formation, and low resistance was optimized using response surface methodology. The composite desirability coefficient was as high as 0.9281, indicating that the two-factor setting conditions yielded the optimal response results. The synergistic effect between Fe and Cu and the ionic conductivity of melanin promote the conversion between Fe2+ and Fe3+ and improve the charge transfer ability of the cathode. The optimized Fe–Cu–Me cathodic catalyst had the highest H2O2 generation (217.91 ± 4.65 mg/L) and the lowest resistance value (190.33 Ω), 4.88 times and 5.05 % that of the unmodified cathode, respectively; also the lowest Fe3+ generation was 32 % and 73 % that of the Fe and FeCu cathodic catalysts, respectively. Moreover, the optimized Fe–Cu–Me cathode catalyst exhibited up to 80 % selectivity for 2-electron oxygen reduction reaction-catalyzed H2O2 generation based and excellent O2 and H2O2 adsorption performance on ring disk electrode analysis and density function theory calculation. This study is the first to use FeCu bimetals combined with insect exuviate melanin as a cathode catalyst for the in situ generation of cathodic H2O2. The high performance and stability of the fabricated electrocatalyst can be used in the subsequent treatment of wastewater through the electro-Fenton process, providing an innovative approach to improve the performance of the cathode.

Investigation of structural, morphological and optoelectronic properties of (Ni, Co)-doped and (Ni/Co) co-doped SnO2 (110) sprayed thin films

The manuscript details the application of spray pyrolysis for the deposition of an economically viable transparent conductive oxide film comprised of (Ni/Co) co-doped SnO2 on a glass substrate. The primary objective of this research was to systematically examine the impact of Ni/Co co-doping on diverse properties of the SnO2 thin film. These properties encompassed the film's structural composition, surface morphology, optical response, and electrical behaviors. A comparison was made with pure SnO2 film, as well as SnO2 films doped with 3 %Ni and 1 %Co. The results indicate that all the samples exhibited a tetragonal structureThe introduction of Co and Ni atoms had no impact on the favored alignment of the (110) plane or the crystal structure of the SnO2 film. The crystallite size of the pure SnO2 film, as well as the (Co, Ni)-doped and (Ni/Co) co-doped SnO2 films, varied within the range of 11 to 20 nm. Scanning electron microscopy (SEM) images were employed to assess how doping and co-doping influenced the surface characteristics of the films. The presence of pores and/or roughness on the surface resulted in a hydrophilic character and a decrease in the contact angle for the doped films (Ni, Co). However, the co-doped film exhibited a hydrophobic characteristic due to the surface enhancement provided by SnO2:3 %Ni:1 %Co. The research also focused on the optical characteristics of the films, showing a positive impact with the proper incorporation of Ni and Co atoms into the SnO2 lattice. It was notably observed that the addition of Ni and Co atoms improves the optical properties of the undoped transparent SnO2 film in the visible spectrum, with a high transmittance of 87 % achieved for the Ni-doped film. Furthermore, the hydrophobic nature achieved by adding a concentration of 3 %Ni to the SnO2:1 %Co film enhances its optical transmission in the range of 300 nm to 750 nm. The SnO2 film shows an improvement in the electrical resistivity upon doping and co-doping with low resistivity value of 2.22 × 10−2 Ω.cm for the film (3 %Ni/1 %Co)-SnO2. Drawing from these insightful results, the study proposes the potential utilization of (Ni/Co) co-doped SnO2 films as transparent electrodes in optoelectronic applications, especially in the manufacturing of thin film solar cells.

Geoelectric analysis for groundwater potential assessment and aquifer protection in a part of Shango, North-Central Nigeria

Groundwater is vital for sustainable development, and this study addresses potable water challenges in Shango, North-Central Nigeria. The main goal is to identify optimal sites for new wells and boreholes, utilizing geological and geo-electrical attributes from existing boreholes and wells. Vertical Electrical Sounding (VES) assessed groundwater potential, aquifer protection, and overburden corrosivity. Sixteen VES stations were probed using Schlumberger array with a maximum current electrode spacing (AB/2) of 200 m using a resistivity meter. The data were interpreted using an automatic computer inversion program, IPI2WIN. The VES results revealed five subsurface geo-electric units, with depths to the aquifer ranging from 58 to 68 m, each exhibiting distinct characteristics contributing to the lithological variability of the research area. Hydraulic conductivity ranged from 0.465 to 0.534 m/day, while transmissivity varied from 9.589 m2/day to 26.029 m2/day across different VES points. Regions exhibiting thick layers and low resistivity values indicate high longitudinal conductivity. Furthermore, areas with low protective capacity are susceptible to the risks of pollution and contamination stemming from leaks and waste sites. The study revealed that all VES points are in practically non-corrosive zones, making them suitable for burying underground tanks with extremely low deterioration rates. Based on geoelectrical characteristics, the study area was divided into three groundwater potential zones: low, medium, and high. These findings provide valuable insights into the groundwater potential and protective capacity of the Shango area, while emphasizing on the vulnerability of these regions and highlighting the pressing need for appropriate preventive measures to safeguard against potential environmental hazards.

20kV Cubicle Maintenance at PT PLN (Persero) APJ Banten Utara Rayon Prima Krakatau

The disturbances that often occur in 20kV cubicles are those with low insulation resistance values ​​caused by several factors such as environmental conditions, humidity levels, dust, temperature, water, pressure disturbances and other disturbances. If this disturbance is left unchecked, it can cause short circuits and electric current leaks. Another disturbance that is often experienced by 20kV cubicles is corona, where this disturbance causes a hissing sound in the cubicle and the appearance of rust on the indoor contact parts of the cubicle. If this condition occurs continuously it can cause serious damage to all 20kV cubicle components and cause losses for customers and PT. PLN (Persero). So to anticipate these problems, maintenance is required on 20kV cubicles. PT. PLN (Persero) carries out annual maintenance of 20kV cubicles to increase the insulation resistance value and overcome the problems of hissing and rust caused by corona events. This Industrial Practice assignment discusses the maintenance of 20kV cubicles in accordance with PT's SOP. PLN (Persero). After carrying out maintenance on the 20kV cubicle, the problems that occur can be resolved, such as increasing the insulation resistance value and the disappearance of the hissing sound and rust on the contacts of the 20kV cubicle.

Multi-criteria assessment of groundwater potential of shallow aquifers in the vicinity of Osun state university, Ikire campus and environs, southwestern Nigeria

In order to investigate the groundwater potentials of shallow water-bearing layers within the vicinity of the Osun State University Campus at Ikire, fifteen vertical electrical sounding (VES) resistivity data were acquired at random. The groundwater potential of the shallow water-bearing layers was inferred from the resistivity data based on three (3) existing criteria namely aquifer resistivity, transmissivity and reflective coefficient. At each VES station, the maximum electrode spreading employed for the resistivity data acquisition was between 200 m and 240 m, with the interpretation of the data carried out using partial curve-matching and computer iterative software. Geoelectric parameters obtained were used to compute the longitudinal conductance, transverse resistance, hydraulic conductivity, transmissivity and reflective coefficient using empirical relationships. The computed parameters were compared with existing classification tables to deduce the groundwater propensity in the shallow water-bearing layers of the study area. Four to five geoelectric layers corresponding to the HQ, HA and HKA geoelectric curve types were observed having lateritic materials as topsoil, sandy clay/clayey sand, weathered/fractured basement and fresh basement. In most cases, the water-bearing layer is mostly of clayey material with high porosity and low permeability and resistivity values that varies from 14.6 Ωm in VES 1 to 65.6 Ωm in VES 6. A few consist of sandy clay also with low resistivity values 76.9 Ωm in VES 7 to 107.1 Ωm in VES 4. The transmitivity values vary from 0.239 m2/day in VES 2 to 2.522 m2/day in VES 5. This same behavior was observed with reflective coefficient values which range from 0.690 in VES 6 to 0.994 in VES 1. The conclusions from the classification tables correlate in most of the VES stations. This study shows that the groundwater potential of the shallow water-bearing layers in the study area is generally poor within 0 to 80 m depth due to the low transmissivity of the clay materials at the shallow depths. Effective groundwater development in the study area must therefore integrate geophysical methods and remote sensing techniques to investigate depths beyond 100 m.

Delineation of aquifer storage potential in response to regional groundwater development

Developing aquifers as part of sustainability efforts toward groundwater development is a tactical approach to meeting water demand and management objectives. Delineation of aquifer storage potential (ASP) and longitudinal conductance (SL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${S}_{L}$$\\end{document}) is a good approach to protect and manage groundwater resources. A Schlumberger configuration was applied to delineate fifteen (15) vertical electrical sounding (VES) stations alongside a 2D electrical resistivity imagery (ERI) profile and regional borehole data to characterize the regional ASP. The results of the study show that the layer resistivity and thickness values of the regional aquifer unit range from 39.9–105 Ωm and 15–44 m, respectively, while the overburden thickness overlays the regional aquifer unit varied between 5–10 m corresponding to the regional borehole data. The weathered/fractured basemen, which constitute the regional aquifer unit were delineated, which consists of shallow, moderate, and deep aquifer zones. The deep aquifer zones fall within the depth of 30–44 m and are considered suitable for groundwater prospective. The weathered layer with appreciably low resistivity values with thick aquifer regolith has also been identified as most suitable for borehole siting. The weathered/fractured encountered within thick aquifer regolith were mapped as the region with a high ASP for groundwater development. In addition, the values of longitudinal conductance, SL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${S}_{L}$$\\end{document} and transverse resistance, RT\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${R}_{T}$$\\end{document} estimated from aquifer parameters vary between 0.21-0.85Ω-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.21-0.85 \\,{\\Omega }^{-1}$$\\end{document} and 1695-3124Ωm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$1695-3124\\, {\\Omega m}^{2}$$\\end{document}, respectively. The SL\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${S}_{L}$$\\end{document} values show that the study area falls within moderate (0.20-0.69Ω-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.20-0.69 \\,{\\Omega }^{-1}$$\\end{document}) and good (0.7-4.9Ω-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.7-4.9 \\,{\\Omega }^{-1}$$\\end{document}), which invariably determined the regional aquifer protective capacity. Thus, the DC geoelectrical approach has been successfully employed in a lateritic-based environment to delineate aquifer-promising zones for regional groundwater development.

Micropolar Fluid Flows Past a Porous Shell: A Model for Drug Delivery Using Porous Microspheres

The creeping flow of an incompressible, bounded micropolar fluid past a porous shell is investigated. The porous shell is modeled using a Darcy equation, sandwiched between a pair of transition Brinkman regions. Analytical expressions for the stream function, pressure, and microrotations are given for each region. Streamline patterns are presented for variations in hydraulic resistivity, micropolar constants, porous layer thickness, and Ochoa-Tapia stress jump coefficient. An expression for the dimensionless drag for the unbounded case of the system is presented, and its variation with hydraulic resistivity and porous shell thickness is presented. The unbounded case represents a theoretical model for oral drug delivery using porous microspheres. It was found that optimal circulation between the porous region and the outer fluid occurred for low values of hydraulic resistivity and for a complete porous sphere.

Effect of Sm dopant on electrocatalytic activity of AgNbO3 perovskite fabricated by sonication method for Oxygen Evaluation Reaction (OER)

Excessive reliance on fossil fuels causes a variety of difficulties and the use of efficient electrocatalysts material has exhibited significant attention for high electrocatalytic activity. Most transition metal oxide materials performance can be enhanced by the incorporation of metals for OER activity. This work presents the synthesis of samarium (Sm) doped silver niobium oxide (AgNbO3) was achieved using sonication techniques. An electrocatalyst, Sm-doped AgNbO3, has shown promising results for oxygen evolution reaction (OER) in alkaline medium with a significant increase in active sites, enhanced electrical conductivity and improved stability. The Sm-doped AgNbO3 electrocatalyst exhibits overpotential of 203 mV and Tafel slope of 35.22 mV dec−1 for OER activity at current densities of 10 mA cm−2. By utilizing, electrochemical surface area (ECSA), the Sm-doped AgNbO3 electrocatalyst exhibited higher ECSA values of 1009 cm−2 with a higher roughness factor of 2008.60. Further, observations of low charge transfer resistance value (Rct = 0.17 Ω) along with a durability of 50 h, indicate that this material is highly efficient and long-lasting as an electrocatalyst for energy conversion systems.

Interpretasi Material Pada Rancang Bak Ukur Skala Laboratorium Dengan Pendekatan Konfigurasi Wenner, Wenner – Schlumberger dan Dipole-dipole

Geoelectric measurements have been carried out using multichannel ResistivityMeter (Geores) tools with Wenner, Wenner-Schlumberger, and Dipole-dipole Configuration approaches on the influence of materials arranged in a laboratory-scale measuring tub design with dimensions of 194x184x80 cm. The measured method is the variation in resistivity value against each trajectory of the material. The method used is the variation of resistivity values for each path of the material that has been arranged in a laboratory scale measuring design. Geoelectric measurements were carried out on 7 lines (5 line in the West-East direction and 2 line in the North-South direction). The spacing between the electrodes of each line is 10 cm with 16 electrodes in one line so that each line has a length of 160 cm or 1.6 m which corresponds to the length and width dimensions of a laboratory scale measuring design. The electrode arrangement parameters are constant with respect to changes in the configuration selected from the geores parameters during geoelectric measurements. The measurement results showed that the identified depth reached 31.2 cm. The low resistivity value category has an interval of 374-4,397 ohm.meters at a depth of 0-12.5 cm, which is the influence of building sand material containing water and soil, while the depth interval is 12.5 - 31.2 cm ohm.meters (material category that is influenced by 2 iron rods, tin tailings sand, granite, gravel) with resistivity values ranging from 12,378–67,498 ohm.meters. From experiments on the influence of the resistivity values of the three Wenner, Wenner-Schlumberger, and Dipole-dipole configurations, it was obtained that the smallest absolute error resistivity value in the Wenner configuration was 5.01% against the overall average absolute error resistivity value of 10.16%.

VLF-EM data conversion into apparent resistivity using the Hilbert transform and its application for shallow fault investigation at Pinggirsari, Bandung Regency, Indonesia

This research presented the ability of the Hilbert transformation of The Very Low Frequency-Electromagnetic (VLF-EM) data to investigate the presence of faults. VLF-EM data was collected in the Pinggirsari village area, Arjasari District, Bandung Regency, West Java, Indonesia. Through the Hilbert transformation, the VLF-EM data was converted into apparent resistivity data and then inverted into a resistivity cross-section. For comparison, qualitative interpretation was also conducted using both the Fraser and the Karous-Hjelt filters. Interpretation results using both the Fraser and Karous-Hjelt filters indicate the presence of faults through tilt-angle curve peaks and apparent current density anomalies. The resistivity cross-section resulting from the Occam inversion of the apparent resistivity data, derived from the Hilbert transformation, accurately delineated fault positions. Resistivity changes around 700–800 m indicated fault proximity to a depth of approximately 150 m, with a good match to the geological map. Within a distance of 0–700 m, low resistivity values were associated with the Malabar tuff, while >700 m, higher resistivity values were associated with the Waringin-Bedil andesite. The Hilbert transform helps in clarifying VLF data interpretation for precise fault detection through resistivity parameters.

Identification of Seawater Intrusion in Groundwater using The Wenner-Schlumberger Configuration (2D) Geoelectric Resistivity Method on Balu Island, Santiri Village, Tiworo Utara Sub-District, West Muna Regency

This research aims to identify sea water intrusion in groundwater using the Wenner-Schlumberger configuration (2D) resistivity geolectric method on Balu Island, Santiri village, Tiworo Utara sub-District, West Muna Regency. This research uses primary data which is resistivty measurement data measured in the field aimed at identifying groundwater aquifers. The interpretation data is then reconstructed into 2D cross-sectional profile using Res2Dinv software. The results obtained in the research area show that sea water intrusion has occurred in groundwater at an average surface depth of up to 39.6 meters with low resistivity values ​​between 0.06 – 807 Ohm-meters