Induced Magnetic Field Research Articles

Entropy Study of Hybrid (Al2O3–Cu/H2O) Nano-Fluid in a Cylindrical Cavity with Wavy Sides Under the Effect of a Parallel Magnetic Field

The convection and entropy of a hybrid nanofluid were investigated in a cylindrical chamber. Inside the cylinder, we have added a rectangular fin with a temperature of Th. Tc applied on the right waving wall. Insulation installed on both the top and bottom walls. The induction of a steady magnetic field is included in this research. Governing equations are resolved by Galerkin finite element method (GFEM) and it’s utilized to treat the controlling equations obtained by giving different characteristics of fluid like The porosity, cylinder rayon and the size of the nano particles with Rayleigh, Hartmann and Darcy numbers. This information is crucial for controlling both fluid flow and the heat transfer rate for normal convection. The results of the solution demonstrate that Da influences the entropy and leads to a decrease in the generation of entropy. The Nusselt mean differs in a straight line with the dynamic. The domain of flows through the sublime modes while it acts contrary with the magnetic force. The use of a rectangular fin inside a cylindrical enclosure rather than traditional ones, as well as the evaluation of its optimal dimensions, was novel in this paper. Moreover, the novelty of this study is that it fills a research gap by looking into the effect of the specific shape of the walls of the porous chamber on heat flux.

Study on magnetization dynamics modulated by spin-orbit-torque in a Ni81Fe19/NiO/Ni81Fe19 multilayered wire

As electrical control of magnetization dynamics opens the door to realize spintronic devices, understanding the microscopic mechanisms of spin current transport and its effect through the antiferromagnetic and interface is crucial. We studied magnetization dynamics modulated by the spin current originated from the spin-orbit-torque using the rectifying planar Hall effect (PHE). In Ni81Fe19/NiO/Ni81Fe19 heterostructure wire deposited on Pt/Ta cross-tie electrode, we measured the rectifying PHE as a function of external magnetic field angle and dc electric current. By measuring the electrical responses of the heterostructure system, we found that the magnetization dynamics can be modulated by the dc electric current flowing through the Pt/Ta electrode.

Identification of XLPE cable insulation defects based on deep learning

The insulation aging of cross-linked polyethylene (XLPE) cables is the main reason for the reduction in cable life. There is currently a lack of rapid and effective methods for detecting cable insulation defects in power-related sectors. To this end, this paper presents a method for identifying insulation defects in XLPE cables based on deep learning algorithms. First, the principle of the harmonic method for detecting cable insulation defects is introduced. Second, the ANSYS software is used to simulate the cable insulation layer containing bubbles, protrusions, and water tree defects, and the effects of each type of defect on the magnetic field strength and eddy loss current of the cable insulation layer are analyzed. Then, a total of 10 characteristic quantities of the total harmonic content and 2nd to 10th harmonic currents are constructed to establish a database of cable insulation defects. Finally, the deep learning algorithm, long short-term memory (LSTM), is used to accurately identify the types of insulation defects in cables. The results indicate that the LSTM algorithm can effectively diagnose and identify insulation defects in cables with an accuracy of 95.83%.

Response to Magnetic Field-Induced Stress on the Demographics and anti-ROS Activity of Aphid Macrosiphum rosae L. (Hemiptera:Aphididae)

Magnetic field plays an essential role for many species, including the migratory pest aphid. Our previous study investigated the long-term exposure of static magnetic fields on the growth development and productivity of the aphid Macrosiphum rosae, however, it is necessary to expand the knowledge of short-term exposure on the insects for a wider spectrum of magnetic field radiation. To achieve this, aphid nymphs were exposed to four magnetic field of induction at 0.065T, 0.1T, 0.176T and 0.28T for 4min under laboratory conditions. The results showed that the short-term magnetic radiation significantly prelonged the four instar development while shortened the first, second and third instar period. 0.28 T radiations caused significantly difference in the parameters of TPOP, adult longevity and total longevity (3.2d, 7.07d, and 8.82d, compared with the control of 4.94d, 8.06d, and 10.23d, respectively). Population parameter of r was 0.057d-1 with 0.28 T compared with the control of 0.150 d-1. The SOD, CAT and POD activity increased more than 30% in static magnetic fields compared with the controls. Our study presents a feasible evidence showing the growth development change as a representative disturbing symptom for short-term exposure to magnetic fields, and the static magnetic field applied being capable of modifying the fitness components and antioxidant defense in aphids.

Structural and flow properties of polysulfone/magnetic carbon nanomaterials under magnetic field induction

AbstractMagnetic carbon nanomaterial (MCN) was prepared by hydrothermal method using microfluidic mixing of ferric tetroxide solution precursors, which was added into casting membrane solution, and magnetic polysulfone (PSF) composite membranes were prepared by phase inversion process after introducing an external magnetic field to treat the casting membrane solution. Microscope image depicts Fe3O4 nanoparticles are uniformly loaded on carbon nanomaterials composed of graphene oxide and carbon nanotubes, and the MCN was obtained with less agglomeration, less Fe2O3 impurities, and magnetization intensity of 53.17 emu/g, which is slightly lower than that of pure Fe3O4 (68.72 emu·g−1). Microscopic cross‐sectional view of the membranes indicate the support pore structure still keep a finger‐shaped pore structure but the surface roughness of composite membrane shows an increase in Ra value compared with the pristine PSF (6.23 nm). The hydrophilicity of membranes show a marked improvement increased in contact angle (from 73.158° to 51.854°), which effect the water flux (from 638.49 to 1089.81 L·m−2·h−1) and permeability (from 1.42 to 2.57 μm2), while the effective diameter of pore in membranes increase (from 1.3385 to 1.9078 μm) through bubble pressure method, and the rejection of bovine albumin decrease slightly (from 93.03% to 90.13%), but the values all reach over 90%, which show good permeate separation performance.

Effect of External Magnetic Field on the Forming, Microstructure and Property of TC4 Titanium Alloy during the Directed Energy Deposition Arc Additive Manufacturing

In this work, the thin wall components of TC4 titanium alloy were produced by using external magnetic field hybrid gas metal welding (EM-GMAW). The effect of the external magnetic field on the forming, microstructure, and property of wire arc additively manufactured TC4 titanium alloy was studied in detail. The results showed that the height of the average deposition layer of EM-GMAW was less than that of GMAW and decreased with the increase of magnetic excitation current, and the width of the average deposition layer of EM-GMAW was greater than that of GMAW. The microstructure of the deposition layer consisted of fine α phase and coarse β grains. Compared with the traditional GMAW, the coarse β grain size in the EM-GMAW was reduced obviously. The maximum size of β grain was decreased by 100μm when the magnetic excitation current of 3A was used. In addition, the EM-GMAW tensile strength in the transverse and horizontal was increased by around 20 MPa and 100 MPa, respectively, compared with that of GMAW.

A SINGLE-LAYER FSS FOR S-, C-, X-, KU- AND K-BAND APPLICATIONS

This research introduces an ultra-wideband frequency-selective surface (FSS) that offers a very good bandwidth for insulation and communication applications. It consists of two layers: a dielectric substrate layer and a metal layer. The basal layer, which is the substrate, is made of FR4; and the top patch, which is the metal, is made of copper. The FSS is constructed without using several layers or several resonators in a single unit cell. This single-sheet, planar-structure-based FSS has an ultra-level bandwidth of 20.3 GHz, ranging from 2.3 GHz to 22.6 GHz. It will be employed in microwave applications in the S, C, X, Ku, and K bands, with a centre frequency of 10.6 GHz. The polarisation and angle stability of the transverse electric (TE) and transverse magnetic (TM) modes are examined, and it was found that they are insensitive up to 90 degrees. Plots depicting the distribution of the magnetic field, surface current, and electric field are used to analyse the structure's physical mechanism. The performances from previous studies are compared and contrasted with that of the current work.

Application of integrated simulation environment SIEMNED to the analysis of the MEPHIST-0 tokamak operation

This paper presents the results of numerical simulation of plasma equilibrium and stability in the MEPHIST-0 tokamak with SIEMNED software and comparison of simulation results with experiments. The determined characteristics of the vacuum chamber show that it significantly affects the entire discharge. For various scenarios of the inductor operation, a comparison of experimental data and simulated currents and magnetic fields induced in the chamber was carried out. For steady-state tokamak operation, a numerical study of equilibrium plasma configurations was carried out depending on the currents in the poloidal magnetic field coils and plasma current. The vertical plasma instability was investigated. The limiting values of plasma ellipticity preventing the vertical plasma instability were numerically determined. Numerical simulations show that plasma equilibrium is supported by induced currents. It was shown numerically that magnetic configuration with ‘zero of higher order’ were obtained before the plasma shot, suggesting consistency between the simulation results and observations.

Validation of an EGSnrc-based Monte Carlo model for a complex 2D-array for technical QA measurements of a linear accelerator.

Multi-axis ionization chamber arrays can be used for quality assurance (QA) and measurement of linear accelerator (linac) specific data. In this work, the ability of the IC Profiler (Sun Nuclear Corp., Melbourne, Florida) detector array to measure the photon beam quality specifier %dd(10) and TPR20, 10 was investigated. To investigate the method for beam energy QA using a two-dimensional detector array, a Monte Carlo-based model of the detector array was developed and validated. A Monte Carlo-based model of the IC Profiler detector array with Quad Wedge accessories was developed in detail from drawings provided by the manufacturer using the egs++ class library from the EGSnrc code system. Monte Carlo simulations were used to calculate the absorbed dose in the 251 ionization chambers of the IC profiler in the 6 MV Elekta Precise radiation field. To validate the results from the Monte Caro simulations, measurements were performed on clinical 6 MV linacs. To vary the photon beam quality of the Elekta 6 MV linac, the current of the bending magnet was varied. Furthermore, the area ratio was calculated from IC Profiler measurements with the Quad Wedgeaccessories. Measurements as well as Monte Carlo simulations confirmed the linear relationship between the area ratio and the investigated photon beam quality specifier %dd(10) and TPR20, 10 for the investigated radiation source. Furthermore, the Monte Carlo-simulated data were within the 95% confidence interval of the linear fit to the measured data. This enabled the Monte Carlo-based IC Profiler model to be used for further investigations. The values were calculated for various electron beam sizes and the angle of incidence on the target of thelinac. A Monte-Carlo-based model of the detector array was developed, which could successfully reproduce measurements, demonstrating that even very complex geometries can be modeled in EGSnrc. Moreover, the study showed that the validated Monte Carlo model has the potential to investigate variations in beam parameters and their effects on AR ratios and %dd(10) that may not be investigated experimentally. While these findings may help users gain a deeper understanding of the QA method, the Monte Carlo model enables other complex investigations, such as the simulation of measurements in the presence of magnetic fields, or the simulation of measurements on novel treatment delivery techniques anddevices.

Research on plasma vertical displacement calculation based on neural network

Plasma vertical displacement control is essential for the stable operation of tokamak devices. The traditional plasma vertical displacement calculation method is not suitable for balancing speed and accuracy simultaneously, which is necessary for real-time feedback control. In this study, neural networks are used to rapidly detect vertical displacement recognition. Based on a fully connected neural network, the vertical displacement calculation model is trained and tested using magnetic data of approximately 2000 shots. To compare the effects of different inputs on vertical displacement calculation, different magnetic measurement diagnostic signals are used to train and test the model. Compared with a full magnetic measurement dataset, 39 magnetic measurement signals (38 magnetic probes and plasma current) show better accuracy with mean square error <0.0005. The model is tested using historical experimental data, and it demonstrates accurate vertical displacement calculation even in the case of a vertical displacement event. In general, neural network algorithm has great application potential in vertical displacement calculation.

Boundary element method with high order impedance boundary condition for Maxwell’s equations

A boundary-element method is introduced for solving electromagnetic scattering problems for coated objects. We develop a new approximate impedance boundary condition with Hodge operator and propose a variationnal formulation for the physical problem. The existence and uniqueness of the solution are studied and we propose a discretization of the unknowns which are magnetic and electric currents with Rao-Wilton-Glisson basis functions to lead to the correct field continuity properties at the interface of different media. And the unknowns are the fluxes of the magnetic and electric currents across the edges of the mesh. Numerical results from the formulation is presented and measurements are compared in order to obtain test cases for the development and validation of numerical method. In the first time, we compare standard impedance boundary condition and high order impedance boundary condition on bodies of revolution with simple topology and we show the increased accuracy of the high order impedance boundary condition solution relative to the standard impedance boundary condition solution. Finally, a benchmark test is treated to show the interest of our method.

Effect of EMBr on Flow in Slab Continuous Casting Mold and Industrial Experiment of Nail Dipping Measurement

In this study, a funnel mold (FM) model of a multi-mode electromagnetic braking (EMBr) device was developed, and the magnetic flux density at different currents was obtained by MAXWELL software. By using the magnetohydrodynamics (MHD) module of FLUENT software, the volume of fluid binomial flow turbulence model and the EMBr mathematical model of the steel/slag flow field were coupled, and the characteristics of the molten steel flow and the liquid-level fluctuation in the 1520 mm × 90 mm FM with the casting speed of 6 m/min were calculated under the effect of the electromagnetic field. The FM liquid-level characteristic information under production conditions was obtained in a nail board industrial experiment and compared with the magnetic-fluid coupling model. The results show that the EMBr can significantly change the flow behavior of molten steel. When the magnetic pole current is not less than 800-600 A, the maximum liquid-level fluctuation height decreases from 18 mm without EMBr to less than 5 mm, and the liquid-level cannot easily entrap slag. Considering the EMBr effect and production cost, the reasonable magnetic pole current should be 800-600 A. The reliability of numerical simulation was also verified by the industrial test results of the nail board.

Hierarchical Fe3O4@LDH-incorporated composite anion exchange membranes for fuel cells based on magnetic field orientation

The trade-off between ionic conductivity and mechanical properties is the key issue facing anion exchange membranes (AEMs) at present. Herein, a new strategy combing three-dimensional (3D) hierarchical nanoarchitecture and magnetic field orientation was proposed to prepare imidazolium-functionalized poly(2,6-dimethyl phenylene oxide) (ImPPO)-based composite AEMs with simultaneously improved ionic conductivity and mechanical strength. Magnetic Fe3O4@LDH microspheres using Fe3O4 as the core and two-dimensional lamellar anion conductor, layered double hydroxide (LDH), as the shell were prepared through a simple co-precipitation method. The as-prepared Fe3O4@LDH was then incorporated into ImPPO matrix and induced by an external magnetic field to fabricate Fe3O4@LDH-orientated composite AEMs. The hierarchical-structured Fe3O4@LDH can not only effectively avoid the stacking of LDH laminates and thus fully play the ion conduction ability of LDH, but also contribute to the formation of continuous OH− ion transport pathway in the composite system after magnetic field induction. The magnetic-field-oriented membrane with 1% Fe3O4@LDH doping exhibited ionic conductivity of 128.9 mS cm−1 at 80 °C, which was 43.1% higher than that of pure ImPPO. Moreover, the high dry strength (30.7 MPa) and satisfactory wet strength and flexibility of the composite membrane were also obtained. The assembled direct methanol fuel cell demonstrated a peak power density of 11.7 mW cm−2, and showed an OCV retention of as high as 94.7% after continuous operation for 100 h, indicating their great potential for fuel cell applications.

Magnetic field and nuclear spin influence on the DNA synthesis rate

The rate of a chemical reaction can be sensitive to the isotope composition of the reactants, which provides also for the sensitivity of such “spin-sensitive” reactions to the external magnetic field. Here we demonstrate the effect of the external magnetic field on the enzymatic DNA synthesis together with the effect of the spin-bearing magnesium ions (^{25}Mg). The rate of DNA synthesis monotonously decreased with the external magnetic field induction increasing in presence of zero-spin magnesium ions (^{24}Mg). On the contrary, in the presence of the spin-bearing magnesium ions, the dependence of the reaction rate on the magnetic field induction was non-monotonous and possess a distinct minimum at 80–100 mT. To describe the observed effect, we suggested a chemical scheme and biophysical mechanism considering a competition between Zeeman and Fermi interactions in the external magnetic field.

Study on Processing Grinding Sludge Conglomerates in Devices with a Rotating Electromagnetic Field

Introduction. The key stages of sludge processing technology are the destruction of conglomerates into metal and non-metal components, as well as the grinding of component particles to obtain secondary raw materials of the required granulometric composition. The use of a rotating electromagnetic field for processing grinding sludge makes it possibleto exclude the application of various means of destruction and grinding, avoiding contact interaction of agglomerates and the walls of the working chamber. Thus, the material consumption of technical means is reduced, and the efficiency of the destruction process is increased. The study aimed at establishing the features and basic patterns of sludge waste processing in devices with a rotating electromagnetic field. Materials and Methods. For the research, grinding sludge was used, which was a collection of conglomerates of arbitrary shape, consisting of 80-85 % of metal chips. An induction method was applied based on establishing the connection of the EMF induced in an induction sensor and the magnetic induction of a rotating electromagnetic field. The influence of induction on the nature of interaction between sludge particles in a rotating electromagnetic field was evaluated by changing the relative EMF signal induced in an inductive sensor. Results. As a result of experimental studies conducted using the induction method, it has been found that the dynamic characteristics of sludge waste conglomerates depend on the induction of a rotating field to a certain value. With an increase in the size of sludge conglomerates, with the same size of ferromagnetic particles entering it, the magnitude of the magnetic field induction required for their destruction decreased. With a decrease in the particle size of conglomerates, the field induction required for the destruction of conglomerate bonds increased. An increase in the number of particles in the conglomerate reduced the value of induction. The degree of destruction of the conglomerate and the grinding of its ferromagnetic particles depended on the duration of the rotating electromagnetic field induction. Discussion and Conclusions. The proposed induction method makes it possible to investigate the influence of electromagnetic field parameters on the change in the state of the magnetic vibrating layer, as well as to evaluate the kinematic characteristics of ferromagnetic medium particles in the magnetic vibrating layer.

Improving conductivity and self-sensing properties of magnetically aligned electroless nickel coated glass fiber cement

The nickel coated glass fiber (Ni-GF) cement (NGFC) holds promise for self-sensing concrete structure due to its improved conductivity and corrosion resistance. This paper is aimed at evaluating the conductivity and self-sensing properties of preferentially orientated NGFC, which was prepared by the magnetic field (MF) induction. The microstructure of electroless Ni-GFs and their arrangement characteristic in cement were observed by optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The anisotropic conductivity and self-sensing properties of as-prepared composites were measured by four-electrode method. The results indicate that the Ni-GFs with uniform nickel coating layer in the as-fabricated composite have an excellent alignment effect under the MF induction. When the Ni-GF content is 2.62 vol%, the composite exhibits maximum anisotropy. The order of the electrical resistivity and percolation thresholds of NGFC is: parallel to MF < without MF < perpendicular to MF. Under the cyclic compression load, the NGFC parallel to MF shows the optimum self-sensing properties. With the increase of loading amplitude and decrease of loading rate, the maximum sensitivities of the as-prepared composite at all directions almost increase linearly. Under the failure compression load, the conductivity of as-prepared composites parallel to MF show a steadier and higher self-sensing response.

Discontinuous Galerkin integral equation method for light scattering from complex nanoparticle assemblies.

This paper presents a discontinuous Galerkin (DG) integral equation (IE) method for the electromagnetic analysis of arbitrarily-shaped plasmonic assemblies. The use of nonconformal meshes provides improved flexibility for CAD prototyping and tessellation of the input geometry. The formulation can readily address nonconformal multi-material junctions (where three or more material regions meet), allowing to set very different mesh sizes depending on the material properties of the different subsystems. It also enables the use of h-refinement techniques to improve accuracy without burdening the computational cost. The continuity of the equivalent electric and magnetic surface currents across the junction contours is enforced by a combination of boundary conditions and local, weakly imposed, interior penalties within the junction regions. A comprehensive study is made to compare the performance of different IE-DG alternatives applied to plasmonics. The numerical experiments conducted validate the accuracy and versatility of this formulation for the resolution of complex nanoparticle assemblies.

Electromagnetic hydrodynamic flow and heat transfer of a Casson nanofluid Fe3O4-blood in a porous medium

Magnetohydrodynamic fluid-flows attract a lot of attention in the extrusion of polymers, in the theory of nanofluids, as well as in the consideration of biological fluids. The considered problem in the paper is the flow and heat transfer of nanoand micro-polar fluid in inclined channel. Fluid-flow is steady, while nano- and micro-polar fluids are incompressible, immiscible, and electrically conductive. The upper and lower channel plates are electrically insulated and maintained at constant and different temperatures. External applied magnetic field is perpendicular to the fluid-flow and considered problem is in induction-less approximation. The equations of the considered problem are reduced to ODE, which are analytically solved in closed form. The influence of characteristics parameters of nano- and micro-polar fluids on velocity, micro-rotation and temperature fields are graphically shown and discussed. The general conclusions given through the analysis of graphs can be used for better understanding of the flow and heat transfer of nano- and micro-polar fluid, which have a great practical application. Fluids with nanoparticles innovated the modern era, due to their comprehensive applications in nanotechnology and manufacturing processes, while the theory of micro-polar fluids explains the flow of biological fluids and various types of liquid metals and crystals.

Исследование параметров микроэлектромеханических систем дефлекторов для определения магнитной проницаемости материала диполей

Micro-electromechanical (MEMS) deflectors with electromagnetic control and an experimental stand for measuring their functional parameters are considered. The electromagnetic control method makes it possible to obtain a high positioning accuracy of the reflected beam along one spatial coordinate, and also provides increased speed with the time of deviation of the light flux to a predetermined position of 5–10 μs. Graphs of experimental and theoretical dependences of the angle of deviation of the light flux on the induction of the control magnetic field of MEMS deflectors are presented. Using the method of successive approximations, the value of the magnetic permeability of the dipole material µ = 120 was selected, and the maximum value of the angular deviation of the light flux along one spatial coordinate was determined, which is 13.50. The MEMS presented in this paper can be used, first of all, as high-speed deflectors and optical flow scanners with a beam diameter of up to 2.5 mm.

Alternativni teorijski model zemljinog EM polja zasnovan na hipotezama o dve komponente polja

Introduction/purpose: The paper describes an alternative theoretical model of the Earth's EM field based on two-component field hypotheses. The paper consists of several parts, one part of which is a model showing the rotation of the magnetically conducting sphere of magnetization M in a foreign magnetic field. The last part defines theoretical models for the calculation of the components of the electromagnetic field of electrically conductive, dielectric and magnetically conductive spheres which are exposed to the influence of a foreign electromagnetic field. Methods: In the work, the responses of electrically conductive, dielectric and magnetically conductive spheres to the influence of external EM fields were investigated using the analytical method. Results: The obtained solutions in the form of analytical formulas will be applied to research the impact of the Sun's EM field on the planets and especially on the Earth. Conclusion: The resulting formulas of the electric and magnetic field strength and induction and their solutions can be applied to electrically conductive, dielectric and magnetically conductive spheres. In comparison to already known formulas, they are simple and have higher accuracy.