High Magnetic Intensity Research Articles

Enhancing electromagnetic properties of NiCuZn ferrites through Nb and Li Co-doping for wireless power transfer

With the rapid development of wireless charging technology, there is a growing demand for ferrite materials with high permeability, high saturation magnetic induction intensity, and low power loss. This study aims to enhance the electromagnetic performance of NiCuZn ferrite by co-doping Nb5+ and Li+. The influence of the doping levels Nb5+ and Li + on the morphology, crystal structure, and electromagnetic properties of NiCuZn ferrite were studied in detail. Structural analysis shows that the lattice constant decreases as the Nb5+-Li+ doping concentration increases, and the NiCuZn ferrite exhibits a high density and homogeneous microscopic morphology at the optimum concentration of x = 0.004. Specifically, at a doping concentration of x = 0.004, the magnetic permeability at 1 MHz measured at 1112.1, the saturation magnetic induction intensity reached 458.98 mT, and the power loss was minimized to 521.85 kW/m3, demonstrating significant improvement in the transmission power of wireless charging applications.

Insights into Afikpo Synclinorium structures: Subsurface analysis and intrusion outlining from airborne magnetic data

The airborne magnetic data over Afikpo Synclinorium were used to highlight subsurface structures and establish the orientations of tectonic features and their influence on the hydrocarbon play of the area. The characteristic trends of the lineaments were achieved through the center for exploration targeting of grid data analysis. The results of the TMI, residual magnetic field, first vertical, horizontal derivative, Analytic signal, and Tilt angle derivative classified the area into regions of high magnetic intensity observed around the northeastern, southwestern, and central portions of the study area. These areas characterized by anomalous signatures of short magnetic wavelengths delineate shallow magnetic sources. Conversely, regions with medium to low magnetic intensities are characterized by long magnetic wavelengths which indicates deep-seated magnetic source(s) and prospect for hydrocarbon (if other play concepts are emplace); due the thick sediment cover at the southern portion of the area (around, southern part of Nguzu, Ohafia, Biakpan, Abriba and Bende areas). The sediment thickness decreases towards north, west, North-east and north-west (dominated by Benue Trough deposit). Depth to the anomaly sources is of two categories, namely, shallow <1.0 km (dominated by NE trending structures) and deep ≥2.5 km. Ground-truthing confirmed the anomalous zone of high magnetic sources in the northeastern and central regions as Tertiary related tectonic-magmatic intrusion. The most prominent intrusion cuts across Amangwu Edda in Afikpo South through Amaeta-Oziza to Cross River State in a fissure form. This intrusion occurrence conformed to the high magnetic signature identified as a dolerite sill within the Afikpo Sub-basin. It stretches over 16 km in length with an average width of about 1.2 km, having its widest part in the northern parts of Mata Hospital Afikpo. The subsurface topographic model indicated that no fewer than 50% of the study area is characterized by sporadically distributed intrusive rocks. The result revealed several structural lineaments with high lineament density at the northcentral corner of the area trending NE-SW with fault lines (slip fault) perpendicular to it, offsetting the Akpoha, Ibii, Amasiri. and Ozara-ukwu ridges. The major drainage systems across the area followed major structural trends perpendicular to the identified major lineaments, passing through the major regional structural displacement pattern of the Basin. The emplacement of these intrusions might have impacted the hydrocarbon potential of the basin.

Performance evaluation of electrical discharge turning of inconel-825 under influence of different magnetic field intensities

ABSTRACT Electrical discharge turning (EDT), an unconventional machining method that utilises electrical discharges generated between an electrode and a rotating workpiece to remove material. However, it faces some challenges with numerous advantages, particularly in the effective removal of debris from the machining zone. In this context, magnetic field assistance is an emerging technique in facilitating the efficient removal of debris during the EDT process. This comparative study compares the effects of various magnetic field intensities on the electrical discharge turning (EDT) process of the Inconel-825 material, a nickel-based superalloy. The experiments were carried out on a self-developed magnetic field assisted electrical discharge turning setup. The experimental results show that increasing magnet intensity enhances the material removal rate (MRR) and improves the overcut (OC) surface finish (Ra) of the machined parts. Additionally, at higher magnetic fields intensity tool wear rate (TWR) has been reported higher. The machined surface has also been observed using SEM and found that the minimum recast layer and debris are formed on the surface at higher magnetic intensity. EDX result also confirmed that the formation of oxide and carbide on the machined surface was minimum at higher magnetic field intensity.

An experimental investigation of an energy regeneration suspension

Energy absorbed from road bumps in traditional suspensions is dissipated as heat. An energy regeneration suspension (ERS) has the capability to capture and store this energy in batteries. It has the potential to be used in several categories of vehicles, encompassing cars, trucks, buses, and even trains. ERS technology shows significant promise in enhancing the fuel efficiency and environmental sustainability of vehicles. In this paper, the design of an ERS that converts kinetic energy into electrical energy is presented. The primary objective is to identify key design parameters that result in high magnetic intensity levels in the air gap of the ERS model. Optimizing these parameters is essential to maximize the advantages of ERS while minimizing any drawbacks. The study investigates the impact of different magnetic permeability materials in the ERS model using ANSYS software. A test rig is established based on the analysis results to assess the energy regeneration efficiency of the ERS model under various excitations. Experimental results demonstrate that ERS models with higher permeability inner sleeves exhibit superior energy regeneration efficiency.

Polycarboxylate functionalized magnetic nanoparticles Fe3O4@SiO2@CS-COOH: Preparation, characterization, and immobilization of bovine serum albumin

Magnetic nanoparticles with increasing superparamagnetism and magnetic targeting have found widespread application in fields such as food and medicine. In this study, polycarboxylated magnetic nanoparticles (Fe3O4@SiO2@CS-COOH) were prepared by surface functionalizing iron tetraoxide (Fe3O4) nanoparticles with ethylenediaminetetraacetic acid (EDTA) as a modifier. The appropriate degree of functionalization modification was obtained by adjusting the EDTA concentration and the ratio of cross-linking agents. The prepared magnetic nanoparticles were analyzed with structural and property characterization. The results showed that the Fe3O4@SiO2@CS-COOH magnetic nanoparticles prepared with 4 % EDTA and cross-linking agents at a molar ratio of 3:4 were uniform in particle size, with an average size of roughly 7 nm, and possessed an abundant carboxylate content (310.8064 μmol/g) and a high magnetization intensity (35.05 emu/g). As a model protein, bovine serum albumin (BSA) was immobilized on the surface of magnetic particles. The largest amount of immobilized protein was 500.4376 mg BSA/g at pH 4.0 and no extra salt ions. According to molecular docking simulations, its immobilization was due to the interaction of amino and carboxyl groups at the Fe3O4@SiO2@CS-COOH/BSA interface. Fe3O4@SiO2@CS-COOH possesses a large number of carboxyl groups, strong protein immobilization, and magnetic responsiveness, which may have potential applications in biomedical and food fields.

A comprehensive study on MnZn ferrite materials with high saturation magnetic induction intensity and high permeability for magnetic field energy harvesting

Manganese-zinc (MnZn) ferrites have important applications in energy conversion, transmission, and harvesting. MnZn ferrite for magnetic field energy harvesting is expected to enhance the saturation magnetic induction (Bs), initial permeability (μi), and Curie temperature (Tc) aspects simultaneously, which is beneficial to the energy harvesting efficiency and safety of the device. In this paper, various formulations of MnZn ferrite samples were prepared by the conventional oxide ceramic process. The cation distribution was determined through Rietveld refinement of XRD patterns Based on this, the M–T curves were fitted by combining Néel molecular field theory with Brillouin functions. The greatest influence on the Curie temperature was found to be the molecular field coefficient between the A and B sites. The magnetization mechanism of MnZn ferrite was comprehensively analyzed by fitting the complex permeability spectrum, magnetocrystalline anisotropy constant, and magnetostriction coefficient. The ratio of domain wall displacement magnetization to domain rotation magnetization shows an increasing and then decreasing trend with Fe content, while |K1| shows an opposite trend. Finally, MnZn ferrite materials with excellent overall performance (Bs = 505mT, μi = 9016, Tc = 447 K) were prepared by investigating the magnetization mechanism.

Upward continuation of total magnetic field intensity data over Sokoto basin, north-western Nigeria

High-resolution aeromagnetic data covering the Sokoto basin, north-western Nigeria were acquired and analyzed using regional enhancement techniques, upward continuation and second order regional. The objective was to delineate major geological structures. The data, which are in form of a grid, were knitted using Oasis Montaj software to obtain the magnetic total field intensity map. The composite grid was reduced to a magnetic equator to align the peaks of magnetic anomalies over the center of their causative bodies. The reduced grid was continued at various planes of observation to understate anomalies due to shallow features. The planes were at 10 km, 20 km, 30 km, 40 km, 50 km, 70 km, and 100 km above the surface. Upward continuation maps produced greatly enhanced the long-wavelength (low wavenumber) anomalies associated with deeper subsurface regional structures. The continuation revealed a high magnetic intensity anomaly in western parts of the area and low magnetic intensity anomalies in the eastern parts. The low magnetic intensity in the eastern part is interpreted as a sedimentary deposit. The residual field was removed from the total magnetic field data using the second-order least square method to get the second-order regional field. The regional field analysis agrees with the upward continuation result.

CuFe3O4@ZIF-2 with oxygen vacancies and multiple reactive sites to efficiently activate peroxymonosulfate for levofloxacin degradation

In this work, CuFe3O4@ZIF-X (X = 1,2,3,4 and 5) composite catalysts with oxygen vacancies and multiple reactive sites were synthesized for the first time by Cu-doped Fe3O4-supported ZIF-X and used to efficiently activate PMS for levofloxacin (LEV) degradation. Influencing factors on LEV degradation were investigated, including the amount of CuFe3O4, pH, catalyst dosage, PMS concentration, coexisting inorganic anions and natural organic matter. In the presence of 1 mM PMS and 40 mg/L CuFe3O4@ZIF-2, 98% removal of LEV (10 mg/L) and 47% mineralization could be achieved within 10 min. The rate constants of CuFe3O4@ZIF-2/PMS were 2.9 times and 4.3 times those of ZIF and Fe3O4@ZIF, respectively. Further investigation found that the introduction of Cu-doped Fe3O4 onto ZIF significantly ameliorates the problem of the reduced catalytic performance of magnetic MOFs due to the high saturation magnetization intensity and severe hindrance of the active sites. Then, the mechanism of LEV degradation, including radical and nonradical pathways, was expounded. Furthermore, the intermediates of LEV degradation were identified, and five possible degradation pathways were proposed. CuFe3O4@ZIF-2 demonstrated a decent catalytic performance even after five consecutive recycles and low metal ion leaching after LEV degradation, greatly improving the problem of secondary contamination.

A magnetic field constrained type of multi-barrel common-rail railgun

Adopting the simultaneous launch mode of small and medium caliber railgun is an important means to increase the firepower density, improve the hit probability and strike efficiency. Based on this requirement, this paper creatively proposed a new multi-barrel simultaneous launch EM railgun, named magnetic field constrained type of multi-barrel common-rail railgun. The basic idea is to integrate multiple single-turn rail launchers with a specific structure into one launcher, and “merge” one rail of each single-turn rail launcher with a tight structure combination and arrange it in the center to form the “common rail” of multi-barrel launcher. The other rail of each rail launcher is evenly distributed around the “common rail” in the form of petals, forming the “outer rail” of each rail launcher. “Common rail” and all “outer rails” together form a multi-barrel rail launcher. With the increase of the number of barrels, the current of each barrel is superimposed many times in the common-rail, which greatly improves the magnetic induction intensity of the inner bore, thus improving the launching efficiency of the system. In order to overcome the problem of high magnetic induction intensity near the common-rail and low magnetic induction intensity near the external rail caused, a magnetic field constrained structure is added to the external rail to form a magnetic field constrained type of multi-barrel common-rail railgun. The basic structure of electromagnetic railgun with different number of barrels is simulated, and the spatial distribution characteristics of magnetic field are analyzed. Based on the magnetic field analysis, the interior ballistic simulation of the multi-barrel common-rail railgun is carried out, and the interior ballistic characteristics and launching efficiency of various numbers of barrels are analyzed. The simulation results show that the magnetic field constrained type of multi-barrel common-rail railgun can effectively improve the magnetic induction intensity near the external rail, improve the uniformity of the magnetic induction intensity distribution in the inner bore, and improve the inductance gradient, thus increasing the system efficiency. The structure of the multi-barrel common-rail railgun provides a new idea for the engineering application of the multi-barrel simultaneous launch mode.

Retrieval of material properties of monolayer transition metal dichalcogenides from magnetoexciton energy spectra

Reduced exciton mass, polarizability, and dielectric constant of the surrounding medium are essential properties for semiconducting materials, and they have been extracted recently from the magnetoexciton energies. However, the acceptable accuracy of the suggested method requires very high magnetic intensity. Therefore, in the present paper, we propose an alternative method of extracting these material properties from recently available experimental magnetoexciton s-state energies in monolayer transition-metal dichalcogenides (TMDCs). The method is based on the high sensitivity of exciton energies to the material parameters in the Rytova-Keldysh model. It allows us to vary the considered material parameters to get the best fit of the theoretical calculation to the experimental exciton energies for the $1s$, $2s$, and $3s$ states. This procedure gives values of the exciton reduced mass and $2D$ polarizability. Then, the experimental magnetoexciton spectra compared to the theoretical calculation also determine the average dielectric constant. Concrete applications are presented only for monolayers WSe$_2$ and WS$_2$ from the recently available experimental data; however, the presented approach is universal and can be applied to other monolayer TMDCs. The mentioned fitting procedure requires a fast and effective method of solving the Schr\"{o}dinger equation of an exciton in monolayer TMDCs with a magnetic field. Therefore, we also develop such a method in this paper for highly accurate magnetoexciton energies.

Amorphous cobalt iron oxide nanoparticles with high magnetization intensity for spin conversion of hydrogen at 77K

Conversion of ortho-hydrogen (o-H2) to para-hydrogen (p-H2) is a necessary process in hydrogen liquefaction, and investigating the catalysts that accelerate conversion is significant. Herein we report the effect of Co/Fe ratio in cobalt iron oxide catalysts on conversion of o-H2 to p-H2 at 77 K, and use XRD, BET, and VSM to explore the influence of different Co/Fe ratios on internal crystal structure, pore size, and magnetization strength. It is concluded that the synergistic effect of crystal structure disorder (increase in active sites), small pores (decrease in distance between o-H2 and active sites), and high magnetization strength (larger torque upon) resulted in the optimal catalytic performance for CFO-3 [n(Co):n(Fe) = 3:10]. When the hydrogen flow is 100 mL min−1, the content of p-H2 in the converted hydrogen is 47.61%.

Lineament mapping of structural-trend analysis over the Niger-Benue River-confluence and its environs, a case study of North-Central Nigeria

Evaluation, analysis and interpretation of aeromagnetic and satellite imagery data acquired over the Nigeria confluence and environs; Northcentral Nigeria were carried out in order to characterise the structural framework of the study area. Fourier domain of digital filtering tools and reduction to magnetic equator (RTE) operations were achieved to enhance the available data’s results. The geomagnetic field of the earth was removed from the aeromagnetic data using the IGRF- 12 model. Results from the 2D radially average power spectrum of the enhanced magnetic data estimate the depth of the magnetic sources as 20m. Several digital image enhancement techniques such as edge enhancement and general contrast stretching were applied to the satellite imagery after which the lineaments extracted from the magnetic data and images were mapped out on-screen using ArcMap 10.8. The RTE map showed a high magnetic intensity values ranging from 33051. 93 nT to 33165.3 nT and trend approximately E -W direction at the eastern and northwestern parts. The digital elevation model (DEM) of the confluence and environs was used to enhance geomorphic features. The structural lineaments orientation obtained from the analysis showed that the primary structural lineaments bearing is NE – SW, ENE -WSW and NNW – SSE and the structural directions derived from the 2D maps are aligned along NE – SW and NW – SE. This conforms to the general trend of structures produced by the Pan African events.

Three-dimensional anisotropic inversion and electrostratigraphic imaging of marine magnetotelluric data to understand the control of crustal deformations by pre-existing lithospheric structures in the Mexican Ridges Fold belt, Southwestern Gulf of Mexico

SUMMARY3-D imaging of the lithosphere in the Mexican Ridges fold belt is important for understanding how the crustal deformations in this basin relate to deep tectonic processes and structures inherited from extinct Jurassic seafloor spreading. Here, we use broad-band (0.0001–0.4642 Hz) marine magnetotelluric data from the basin to reconstruct the 3-D anisotropic resistivities of the lithosphere and their spatial gradients. The resistivity gradients maxima enabled independent definition of important geological boundaries (seen on collocated seismic reflection data) and estimation of crustal thickness. We found anomalous layered zones of low resistivity and high electrical anisotropy at 5–8 km depth (coinciding with the regional detachment zone in Eocene shales in 3-D seismic data) and in the upper mantle which we interpret as indicating intense deformation and/or recent magmatic influence. We also found a banded crystalline basement structure across the fossil spreading centre comprising WSW–ENE trending, 6–10 km wide, electrically resistive subvertical sheets with conductive and anisotropic borders, which merge into a basal resistive stock-like body at 15–20 km depth. These are cut or bounded by later NNW trending major faults. These WSW and NNW structural trends correlate with the previously interpreted transform and normal faults that formed during the Late Jurassic opening of the Gulf of Mexico only if rotated clockwise by 25–30°. Surprisingly, the rugged thrust-related seabed is offset at the projected positions of the steep resistive-conductive basement sheets (which also have spatially coincident high magnetic intensity and seismicity) enabling us to infer they represent magmatic intrusions facilitated by pre-existing faults. Their conductive borders spatially coincide with possibly fluid-filled vertical fracture-sets in the overlying sediments seen in seismic data which we interpret as hydrothermal fluid pathways. We infer that a magmatic body recently intruded our study area, its ascent controlled by pre-existing basement structures, and influenced the deformation of the Neogene sequences and the seafloor topography.

Geophysical and geological investigation of the spatial and subsurface extent of the Segwagwa and Masoke igneous ring complexes in southeast Botswana: Geotectonic implications

The Segwagwa-Masoke Igneous Ring Complex (SMIRC) occurs within the Kanye Basin and is part of a suite of elliptical igneous complexes in SE Botswana. We used map analyses and three-dimensional (3D) joint inversion modelling of airborne magnetic and ground gravity data to examine the internal structure and configuration of the SMIRC. Our results show the SMIRC as nested ring-within-ring structures characterized by high magnetic intensity and high gravity anomalies. The Segwagwa and Masoke Complexes are both elliptical in shape and cover surface areas of 127 km2 and 26 km2, respectively. Additionally, our results reveal two new intrusions, termed here Selokolela A and B, which form part of the SMIRC, bringing the total number of individual intrusions in the SMIRC to four. The 3D models suggest that the Segwagwa and Masoke Complexes are vertically oriented and steep-sided, extending to 12 km and ∼5 km depths, respectively. Two-dimensional (2D) forward modelling of the gravity and magnetic data confirms that the Segwagwa Complex is steep-sided and has a depth extent of 13 km. We interpret the ring-shaped magnetic anomalies to represent magma crystallization along concentric fracture zones that developed in association with the collapse of calderas.

Ferrite materials with high saturation magnetic induction intensity and high permeability for magnetic field energy harvesting: Magnetization mechanism and Brillouin function temperature characteristics

Manganese-zinc (MnZn) ferrites play an indispensable role in energy transform and harvesting. It is notable to mention that the combined enhancement of initial permeability (μi), saturation magnetic induction (Bs) and Curie temperature (Tc) is conducive to improving the output power and safety of magnetic field energy harvesting devices. In this paper, high permeability MnZn ferrites were synthesized by a conventional oxide ceramic method. The thermomagnetic curves of MnZn ferrites were fitted according to the Néel molecular field theory (NMFT) and the Brillouin function. Then the molecular field coefficient γaa, γab, γbb, and Tc were calculated. Aiming at the magnetization mechanism of permeability, the contributions of domain wall motion and spin rotation were analyzed by fitting the complex permeability spectrum. Furthermore, the temperature characteristics of μi and Bs are analyzed, and we simulated and compared the effect of different magnetic properties of MnZn ferrites on the output of non-invasive magnetic field harvester. The MnZn ferrites with superior comprehensive performance own potential applications for non-invasive magnetic field harvester.

Research on the mechanical and tribological properties of coating reinforced by a pulsed magnetic field during the remelting process

Remelting technology can effectively reduce the pores and defects, increase the bonding strength and form good metallurgical bonding in coatings. However, coating remelting is a metallurgical process of surface recrystallisation that destroys a large number of nanocrystalline structures in the original coating during quench forming. Therefore, our research group designed a pulsed magnetic field-assisted coating remelting device and prepared coatings by applying a high pulse magnetic intensity during coating remelting. The results show that the tribological properties of the remelted coating are greatly improved by the application a pulsed magnetic field and the friction loss volume of the coating decreases from 0.285× 10−3 mm3 to 0.154 × 10−3 mm3. The distribution of residual stress is more concentrated and residual compressive stress appears. The bonding strength increases from 30 MPa to 51.6 MPa and the hardness increases from 583.0 MPa to 751.0 MPa. Furthermore, when the friction pair is in full contact with the coating, the pore reduction can significantly reduce the interference of pore defects in the coating with the friction pair. The orderly magnetic domain makes the stress distribution in the coating orderly. The residual tensile stress improves the stress mode of the coating. The grain boundaries increase after grain refinement and the crystallinity increases. All these improve the wear resistance of the coating.

Structural Evaluation for Groundwater Within the Crystalline Basement of Ilorin, Nigeria, Using Multisensory Data Techniques

Within the hard rock terrains, stream channels are suspected to be controlled by fractures and joints. In the same light, the topographic lineaments and the lineaments observed from the aeromagnetic anomalies are expected to reflect the structural trends within the complex. This study has therefore adopted multi-data sets results first on a regional scale to depict the structural fabric of Ilorin Sheet 223 and then at the chosen location of the University of Ilorin Main Campus, which is made up of the Basement Complex rocks. From the remote sensing map of Ilorin Sheet 223 structural trends have been divided into two: the NE-SW and the NW-SE structural trends. The aeromagnetic anomalies divide the rocks types into metamorphic (low-to-medium magnetic intensity) and igneous (high magnetic intensity) rocks. The resistivity data interpretation reveals the weathered basement at the University of Ilorin ranges from 5m to 20m. The radial sounding results reveal the structural trend to be NW-SE and NE-SW with the interconnection of joints. The radial sounding shows the rock type in the University of Ilorin Campus to be quartzitic, clayey and igneous as judged from the near hexagonal and elongated shapes of the polygons. The results reveal a good agreement between the trends of fractures derived from the radial vertical electrical sounding and that from the lineament maps. Areas with low bedrock resistivity, thick overburden, presence of two or more interconnected fractures, and high co-efficient of anisotropy indicate intense fracturing and thus, indicate areas of high groundwater potentiality and good water quality.

Enhanced adsorption performance of sulfamethoxazole and tetracycline in aqueous solutions by MgFe2O4-magnetic biochar.

Biochar has been reported as an excellent adsorbent for antibiotics, but the application faces the challenges of complicated separation. Here, MgFe2O4-magnetic biochars (MBCs) derived from corncob were synthesized at 300 °C to remove sulfamethoxazole (SMX) and tetracycline (TC) simultaneously. The characteristics of MBC300 had a high magnetic intensity. MBC300 had the maximum adsorption capacity of SMX with 50.75 mg/g and the high adsorption amount of TC with 120.36 mg/g respectively, which were 4.49 and 6.48 times those of BC300. MBC300 had the advantage of energy conservation compared with MBC450 and MBC600. The better fitting kinetics and isotherms indicated that the SMX and TC sorption onto MBC300 were governed by chemisorption. FTIR and XPS analyses confirmed that the SMX sorption onto MBC300 was dominated by polar interactions and π-π electron donor-acceptor interactions (π-π EDA). Furthermore, the TC sorption was involved in pore filling, π-π EDA, H-bonds, and surface complexation. MBC300 presented effective adsorption of SMX and TC over a wide range of pH. The competition between antibiotics and coexisting pollutants of dissolved organic matter (DOM), Ca2+, CO32-, and PO43- significantly inhibited the sorption. The results indicate that MBC300 is an effective and promising adsorbent to treat SMX and TC simultaneously.

An ultra-high-resolution autonomous uncrewed helicopter aeromagnetic survey in Izu-Oshima Island, Japan

We conducted a high-resolution aeromagnetic survey using an autonomously driven uncrewed helicopter that flew as low as several tens of meters above the ground along precise flight tracks with 1 m accuracy. The geomagnetic total intensity was measured by a total intensity magnetometer suspended beneath the helicopter at a ~ 50 m or less flight spacing over the entire caldera of Mt. Mihara, located on Izu-Oshima Island, Japan. From the observed geomagnetic data, we estimated high-resolution subsurface magnetization intensity. A high average magnetization intensity of 13.5 A/m was obtained for the entire caldera. The distribution of the magnetization intensity was not only consistent with the results of conventional airborne surveys, but it also had a high spatial resolution of less than 100 m. Highly magnetized areas were observed along the NW–SE lines that intersected the summit pit crater, Crater A, which is consistent with the principal stress direction of Izu-Oshima Island. These highly magnetized areas might be solidified magma that did not reach the surface during past eruptions. A large and deep-rooted weakly magnetized area was found just outside of the NE side of the central cone, which corresponds to the location of Fissure B, and the conduit must have been demagnetized at the previous event. Other weakly magnetized areas were also observed at the N, E, and SW sides around the pit crater. These regions correspond to the location of fumaroles in the crater. The high-resolution subsurface magnetization imaged by the autonomous uncrewed helicopter will be helpful for the mitigation of future eruption damage by enabling the assessment of potential fissure eruption areas.

Mathematical modeling of unsteady flow with uniform/non-uniform temperature and magnetic intensity in a half-moon shaped domain

The mathematical modeling of two-dimensional unsteady free convective flow and thermal transport inside a half-moon shaped domain charged in the presence of uniform/non-uniform temperature and magnetic effects with Brownian motion of the nanoparticles has been conducted. Thirty-two types of nanofluids in a combination of various nanoparticles and base fluids having different sizes, shapes, and solid concentrations of nanoparticles are chosen to examine the better performance of heat transfer. The circular boundary is cooled while the diameter boundary is heated with uniform/non-uniform temperature. An external uniform/non-uniform/periodic magnetic field is imposed along diameter. The powerful partial differential equations solver, finite element method of Galerkin type, has been engaged in numerical simulation. The numerical solution's heat transfer mechanism reaches a steady state from the unsteady situation within a very short dimensionless time of about 0.65. The thermal transport rate enhances for increasing buoyancy force whereas decreases with higher magnetic intensity. The uniform thermal condition along the diameter of half-moon gives a higher thermal transport rate compared to non-uniform heating conditions. The non-uniform magnetic field provides greater values of the mean Nusselt number than the uniform field. In addition, the outcomes also predict that a better rate of temperature transport for kerosene-based nanofluid than water-based, ethylene glycol-based, and engine oil-based nanofluid. The heat transfer rate is observed at about 67.86 and 23.78% using Co-Kerosene and Co-water nanofluids, respectively, with an additional 1% nanoparticles volume fraction. The blade shape nanoparticles provide a better heat transfer rate than spherical, cylindrical, brick, and platelet shapes. Small size nanoparticles confirm a higher value of average Nusselt number than big size. Mean Nusselt number increases 22.1 and 5.4% using 1% concentrated Cu-water and Cu-engine oil nanofluid, respectively than base fluid.