Induced Magnetic Field Research Articles

Identification of the pathogenesis features of various phenotypes of multiple sclerosis based on the study of the morphological functional connectivity of subcortical gray matter structures

Objective. The aim of study: to investigate the functional changes in the thalamus, amygdala, and hippocampal region using functional MRI at rest and determine their clinical significance in various types of MS.Materials and methods. 68 patients with a diagnosis of multiple sclerosis (MS) were examined: 40 patients with a relapsing-remitting MS (RRMS) in remission and 28 patients with secondary progressive MS without signs of activity and progression (SPMS). The control group consisted of 10 healthy people of the appropriate age and gender without neurological and somatic diseases. All patients and controls underwent MRI of the brain on a Siemens Tim Trio tomograph with a magnetic field induction of 3.0 TL, using contrast enhancement, T1 gradient echo protocols, REST-BOLD, and subsequent processing of the data obtained using CONN 19с software.Results and conclusion. In the course of the study, various patterns of changes in functional connections were found: in patients with RRMS, there is a decrease in the intensity of connections of the thalamus with other brain structures and a decrease in their number. In patients with RRMS, a greater number and intensity of connections within the thalamus and other structures of the brain were detected compared to SPMS. In patients with RRMS, there is a significant decrease in the connectivity parameters of the hippocampal formation, which is expressed on the left, and in the case of the amygdala complex – on the right, this is manifested in a total decrease in the intensity of connections with other brain structures and a decrease in their number. Thus, the method of functional MRI at rest makes an additional contribution to the understanding of neurodegenerative processes in various phenotypes of multiple sclerosis.

Impacts of magnetic permeability on electromagnetic data collected in settings with steel-cased wells

SUMMARY Electromagnetic methods are increasingly being applied in settings with steel infrastructure. These include applications such as monitoring of CO2 sequestration or even assessing the integrity of a wellbore. In this paper, we examine the impacts of the magnetic permeability of a steel-cased well on electromagnetic responses in grounded source experiments. We consider a vertical wellbore and simulate time and frequency domain data on 3-D cylindrical meshes. Permeability slows the decay of surface electric fields in the time domain and contributes to a phase shift in the frequency domain. We develop our understanding of how permeability alters currents within, and external to, the casing by focussing first on the time domain response and translating insights to the frequency domain. Following others, we rewrite Maxwell’s equations to separate the response into terms that describe the magnetization and induction effects. Magnetic permeability impacts the responses in two ways: (1) it enhances the inductive component of the response in the casing and (2) it creates a magnetization current on the outer wall of the casing. The interaction of these two effects results in a poloidal current system within the casing. It also generates anomalous currents external to the casing that can alter the geometry and magnitude of currents in the surrounding geological formation. This has the potential to be advantageous for enhancing responses in monitoring applications.

Improvement of the magnon-magnon coupling strength in Y3Fe5O12/Py heterostructures

Magnon-quasiparticle couplings perform magnon information transferences and transports, thus controlling the coupling strengths is significant for novel information function devices. Here, we report the modulation of the magnon-magnon (M−M) coupling strength in Y3Fe5O12/permalloy (YIG/Py) heterostructures via ferromagnetic resonance (FMR) technique. The anti-crossing gap gc enhances 80 Hz by changing the radio frequency (rf) microwave power, which could be ascribed to the enhancement of the dipolar interaction and spin pumping effect. Furthermore, the gc decreases with the increasing angle θ between external magnetic field and rf current due to the increase of magnon relaxation. Moreover, the FMR linewidths change with increasing angle θ due to the magnetic anisotropy parameters and the two-magnon relaxation mechanism induced by the more oblique external field.

Computational and Stability Analysis of MHD Time-Dependent Thermal Reaction Flow Impinging on a Vertical Porous Plate Enclosing Magnetic Prandtl Number and Thermal Radiation Effect

The aim of the present study is to investigate magnetohydrodynamic (MHD) time-dependent flow past a vertical slanted plate enclosing heat and mass transmission (HMT), induced magnetic field (IMF), thermal radiation (TR), and viscous and magnetic dissipation characteristics on a chemical reaction fluid flow. A boundary layer estimate is taken to develop a movement that exactly captures the time-dependent equations for continuity, momentum, magnetic induction, energy, concentration, generalized Ohm’s law, and Maxwell’s model. Partial differential equations designate the path occupied by the magnetized fluid as it passes through the porous matrix. In addition, a heat source is included in the model in order to monitor the flow nature in the current study. Because of the nonlinearity in the governing equations, the mathematical models are computed numerically by RK4 method. Further, tables and graphs are depicted to elucidate the physical influence of important factors on the flow characteristics. The novelty of the present work is investigating the irregular heat source and chemical reaction over the porous rotating channel. It is perceived that high thermal radiation occurs with increases in temperature and concentration. It is witnessed that the IMF effect is diminished for large values of magnetic Prandtl number (MPN). It is also analyzed that with increasing the heat source factor, the velocity of the fluid enhances. For stability analysis, the existing effort is compared with the published work and good agreement is found. Moreover, the residue error estimation confirms our solution.

Entropy generation in unsteady stagnation flow through porous media in the presence of a high magnetic Reynolds number with a uniform heat source: renewable energy applications

The present model’s major focus is on entropy production and Newtonian, incompressible two-dimensional temperature-dependent stagnation point with uniform heat source factors in a porous channel. Furthermore, the induced magnetic field (IMF) is employed in this flow analysis, which is created by the movement of electrically conducting fluid. Entropy generation (EG) is an important aspect of any heat transfer development since it helps to reduce the irreversibility factor in a system. EG analysis has several applications in traditional industrial fields requiring fluid flows and heat transfer. As a result, the current study is concerned with the effects of EG. The relevant similar transformations are used to convert partial governing equations arising in the present model into ordinary differential equations (ODE). The bvp4c built-in code in MATLAB programming is then utilized to crack highly nonlinear equations. We arrive at numerical solutions by employing thebvp4c built-in code in MATLAB software. The results are plotted and discussed for various embedded parameters. It is discovered that because of low friction, the porosity parameter decreases the velocity and induces the magnetic boundary layer. Unsteady parameter and heat source parameters accelerate Bejan number, whereas the heat source and porosity constraints accelerate entropy analysis.

Design and construction of a Halbach magnetizer for magnetic treatment of fluids

At present, the application of magnetizers (magnetic conditioners) is increasingly booming, in the different branches of socioeconomic work such as Industry, Agriculture, and Medicine. In this work the calculation and design of a magnetizer is proposed; formed by equal permanent magnets type Halbach with rectangular shape, distributed and confined in a non-ferromagnetic structure, circular section in the form of a ring, consisting of an octagonal inner circle, with a magnetic field induction (25,7-42,8) mT and a homogeneity of magnetic field, in the volume of interest, of 1,5 x 10-2 ppm (in a sphere of radius of 0,025 m), in the center of the configuration lines are distributed transversally for different water flow capacities.

Numerical analysis of magneto-radiated annular fin natural-convective heat transfer performance using advanced ternary nanofluid considering shape factors with heating source

ApplicationsThe fins performance under natural convection is essential to make it more functional for large scale applications more specifically in thermal engineering. For this, it is important to introduce new techniques to enhance the fins performance instead of traditional way. Thus, this study introduces a new way to make the fin more efficient using ternary nanomaterial under nanoparticles shape factor. The annular fin significantly contributes in electronics to exhaust the hot air, injector pumps and applied thermal engineering. Purposeand Methodology: This work focuses on the fin energy model using shape factors. Therefore, the ternary nanofluid, natural convection, thermal radiation and magnetic field used to develop the model. Then, the RKF-45 implemented to investigate physical results. Core findingsKeen analysis of the physical results reveal that the coefficient of thermal conductivity ranging from 0.0% < α1 < 3.0% and natural convection have major role in the fins energy performance. Induction of magnetic field and thermal radiation Rd are reliable for the fin cooling and, heating source Q1 = 0.2,0.4,0.6,0.8 promote the fin energy capability in the existence of (Al2O3–CuO–Cu) ternary nanomaterial with concentration factor up to 2%. On the comparative basis, ternary nanomaterial makes the fin more efficient than hybrid nanomaterial.

INCREASING THE EFFICIENCY OF THE SURFACE-MOUNTED ULTRASONIC ELECTROMAGNETIC-ACOUSTIC TRANSDUCER ON ACCOUNT OF THE MAGNETIC FIELD SOURCE

Model studies were carried out using the COMSOL Multiphysics package, aimed at ensuring the forming of a permanent magnet magnetic field at a considerable distance to a ferromagnetic product from its pole, which is necessary to create efficient portable ultrasonic electromagnetic-acoustic transducers of thickness gauges and testing and diagnostic devices. It is theoretically shown and experimentally confirmed that for portable measuring ultrasonic devices it is expedient to set the height of the permanent magnet at about 60 mm and the cross section of the magnet pole 50x50 mm2. At the same time, with a gap between the magnet pole and the product of about 30 mm, the value of the normal component of the magnetic field induction near the surface of the object is about 0.3...0.4 T, which is sufficient for thickness gauging or diagnostics of ferromagnetic products using the ultrasonic pitch-and-catch method. References 19, figures 8.

Theoretical study of ARRHENIUS‐controlled heat transfer flow on natural convection affected by an induced magnetic field in a micro‐channel

AbstractThe current study analyzes the implications of an Arrhenius‐controlled heat transfer fluid on free convection in a micro‐channel confined by two immeasurable vertical parallel plates that are electrically non‐conductive due to an induced magnetic field (IMF) effect. The governing coupled nonlinear equations are ordinary differential equations, and the dimensionless steady‐state solutions were determined using the homotopy perturbation method (HPM). The derived results were discussed and represented graphically with the help of illustrative line graphs for momentum, IMF, temperature, and volume flow rate for the major controlling parameters, namely arrhenius kinetics, rarefaction, wall ambient temperature difference ratios, and Prandtl magnetic number. Thermo‐physical properties that are of engineering interest, like sheer stress and Nusselt number, are also computed and displayed. It is pertinent to report that the velocity of the fluid increases as a result of chemical reactions and rarefaction factors, whereas strengthening the Prandtl magnetic number decreases the volume flow rate. Also, numerical data was obtained and presented in tabular form to compare this research outcome to those of Jha and Aina, and great consistency was found. Microelectronics and microfluidics are some areas where this study can find relevance.

Magnetic monopoles with no strings attached: a portal to the dark side of dual electrodynamics

It has long been known that in the absence of electric charges and currents, Maxwell’s electromagnetism in 4 dimensional vacuum Minkowski space-time is invariant under SO(2) dual transformations that mix its electric and magnetic fields. Extending this symmetry to include the coupling to electrically charged matter, requires a dual coupling to magnetically charged matter as well, leading to Maxwell equations for SO(2) dual electrodynamics. Based on a doubled ensemble of SO(2) dual 4-vector gauge potentials which does away with the need of Dirac string singularities for magnetic monopoles, a local Lagrangian action principle for SO(2) dual electromagnetism is known, which manifestly displays all the required space-time and internal symmetries, and reduces to the experimentally well established Maxwell electrodynamics in the absence of magnetic charges and currents. Applying the same considerations for the matter action of electrically and magnetically charged point particles, a unique SO(2) dual generalised Lorentz force is identified for SO(2) dual electrodynamics, truly different from the usual SO(2) dual invariant choice motivated by simplicity, but yet made arbitrarily and which does not derive from some action principle. This generalised Lorentz force involves a single real and new coupling constant of unknown value, without the requirement of a Dirac–Schwinger–Zwanziger quantisation condition for electric and magnetic charges of dyons. A physical consequence for SO(2) dual electrodynamics of this coupling constant if nonvanishing, is to open a channel, or portal between the otherwise mutually totally “dark” sectors of electric and magnetic charges for electromagnetic interactions.

A novel dual-polarized gain-enhanced microstrip patch antenna

ABSTRACT A broadside direction gain-enhanced low-cost dual-polarized microstrip patch antenna has been presented. The proposed antenna consists of a slot-loaded cross-shaped patch and shorting pins. The orthogonal polarized radiating elements works in TM05 and TM12, meanwhile slot-loaded excite TM01. The equivalent magnetic currents (EMCs) amplitude, frequency, and flow direction of the TM12 are controlled by shorting pins to form the broadside gain enhancement. The superposition of them can enhance the gain in the broadside direction. The proposed antenna is coaxial feed. The substrate is divided into two layers: air and FR4. A copper column is added to the air layer to greatly improve the polarized isolation of the antenna. The size of the proposed antenna is 2.29λ 0×2.29λ 0×0.069λ 0 (λ 0 is the wavelength of free space at the central frequency). The simulated maximum realized gain is 12.59 dB, and the realized gain is better than 11.53 dB in operating band. The measured maximum realized gain is 12.05 dB, and the realized gain is better than 10.04 dB. The dual-polarized microstrip patch antenna has the advantages of low cost and high gain, which can be used in the modern wireless communication system.

Study on the Single Sheet Measurement Method for AC Magnetic Measurement on Grain-Oriented Electrical Steel

To quickly and accurately measure the AC magnetic properties of grain-oriented electrical steel by means of the existing measuring system designed for the magnetizing current method (MC), specifically the SST (92) single sheet method, in this work, the H-coil (HC) measuring system, which directly senses the magnetic field strength of the tested sample, was designed to measure the AC magnetic properties of the grain-oriented electrical steel. The assumed effective magnetic path length introduced in the MC method was corrected by comparing the measurement results obtained by means of HC and MC methods. The results found that specific total loss measured by the HC method was significantly lower than that measured by the classical magnetizing current (MC) method. Taking the HC method as the reference, the influencing factors of the effective magnetic path length was studied. It was found that the actual effective magnetic path length depends on the investigated sample characteristics, the measurement conditions, as well as yoke characteristics. The actual effective magnetic path length introduced in the MC method is examined to be more than 450 mm, fluctuating around 468 mm.

Gravity as a gapless phase and biform symmetries

We study effective field theories (EFTs) enjoying (maximal) biform symmetries. These are defined by the presence of a conserved (electric) current that has the symmetries of a Young tableau with two columns of equal length. When these theories also have a topological (magnetic) biform current, its conservation law is anomalous. We go on to show that this mixed anomaly uniquely fixes the two-point function between the electric and magnetic currents. We then perform a Källén-Lehmann spectral decomposition of the current-current correlator, proving that there is a massless mode in the spectrum, whose masslessness is protected by the anomaly. Furthermore, the anomaly gives rise to a universal form of the EFT whose most relevant term — which resembles the linear Einstein action — dominates the infrared physics. As applications of this general formalism, we study the theories of a Galileon superfluid and linearized gravity. Thus, one can view the masslessness of the graviton as being protected by the anomalous biform symmetries. The associated EFT provides an organizing principle for gravity at low energies in terms of physical symmetries, and allows interactions consistent with linearized diffeomorphism invariance. These theories are not ultraviolet-complete — the relevant symmetries can be viewed as emergent — nor do they include the nonlinearities necessary to make them fully diffeomorphism invariant, so there is no contradiction with the expectation that quantum gravity cannot have any global symmetries.

Ultra-compact bifunctional transparent meta-device based on bi-layer anisotropic Huygens’ metasurface

Bifunctional transparent meta-devices play an essential role in electromagnetic (EM) integration because of their advantages in extensive applications in modern devices. However, most available devices are achieved by multi-layer dielectric cascaded structures due to the requirement of 360° transmission phase shift, which suffer from the issues of high loss, complex mode control, complicated fabrication and device-integration inconvenience. Herein, a bi-layer anisotropic Huygens’ metasurface is proposed to design ultra-compact bifunctional transparent meta-devices based on the polarization dependent property via inducing the orthogonal electric and magnetic currents simultaneously to excite the Huygens’ resonance. As proof of the concept, a bifunctional transparent meta-device is designed, fabricated and experimentally demonstrated, which behaves as a beam deflector and a focusing lens under excitation of x-polarized and y-polarized incident waves, respectively. Numerical results coincide well with the experiments, indicating that the measured total efficiency of the beam deflector is about 64% at 10 GHz and the measured relative efficiency of the focusing lens achieves about 80%. Our findings provide a novel low-cost, easy-to-fabricate and convenient-to-setup solution for bifunctional transparent meta-devices and could stimulate their promising applications in many EM integration systems.

Fast Wide-Band RCS Analysis of the Coated Target Based on PBR Using EFIE-PMCHWT and the Chebyshev Approximation Technique

The Chebyshev approximation technique (CAT) combined with the MoM based on the electric-field integral equation (EFIE) and the Poggio–Miller–Chang–Harrington–Wu–Tsai (PMCHWT) integral equation is proposed to efficiently calculate the wide-band radar cross-section (RCS) based on passive bistatic radars (PBR). The EFIE-PMCHWT equations can be used to analyze the electromagnetic scattering of coated targets. The combination with CAT only requires computing the electric and magnetic currents at a few Chebyshev frequency points, which can be employed to obtain the electric and magnetic currents over the entire frequency band. In this study, the RCS values of a coated target calculated by the hybrid EFIE-PMCHWT-CAT based on passive bistatic radar (PBR) were found to be consistent with that calculated by the MoM based on the EFIE-PMCHWT. The validity of the hybrid method is verified by several numerical examples. Compared with the conventional MoM method, the hybrid method can greatly improve the efficiency for electromagnetic scattering problems over a wide frequency band.

Chaotic dynamics from coupled magnetic monodomain and Josephson current.

The ordinary (superconductor-insulator-superconductor) Josephson junction cannot exhibit chaos in the absence of an external ac drive, whereas in the superconductor-ferromagnet-superconductor Josephson junction, known as the φ_{0} junction, the magnetic layer effectively provides two extra degrees of freedom that can facilitate chaotic dynamics in the resulting four-dimensional autonomous system. In this work, we use the Landau-Lifshitz-Gilbert model for the magnetic moment of the ferromagnetic weak link, while the Josephson junction is described by the resistively capacitively shunted-junction model. We study the chaotic dynamics of the system for parameters surrounding the ferromagnetic resonance region, i.e., for which the Josephson frequency is reasonably close to the ferromagnetic frequency. We show that, due to the conservation of magnetic moment magnitude, two of the numerically computed full spectrum Lyapunov characteristic exponents are trivially zero. One-parameter bifurcation diagrams are used to investigate various transitions that occur between quasiperiodic, chaotic, and regular regions as the dc-bias current through the junction, I, is varied. We also compute two-dimensional bifurcation diagrams, which are similar to traditional isospike diagrams, to display the different periodicities and synchronization properties in the I-G parameter space, where G is the ratio between the Josephson energy and the magnetic anisotropy energy. We find that as I is reduced the onset of chaos occurs shortly before the transition to the superconducting state. This onset of chaos is signaled by a rapid rise in supercurrent (I_{S}⟶I) which corresponds, dynamically, to increasing anharmonicity in phase rotations of the junction.

Characterization of Premixed Flames with Ethanol Fuel affected Magnetic Field Induction

The purpose of this study was to determine the effect of magnetic field induction on the characteristics of premixed ethanol combustion flames. Petroleum reserves will increasingly be depleted if alternative energy is not found. Therefore, various breakthroughs are needed to prevent an energy crisis from occurring. Simultaneously the researchers are also trying to find equipment that can save fuel consumption. To get a more effective and efficient flame, you can apply a magnetic field effect to the burning fire, especially in terms of the rate of burning of the fire. Fuel oil under normal conditions tends to be irregular and grouped together. By providing a magnetic field to induce the fuel oil, the hydrocarbon bonds will break and will make the chemical composition more homogeneous. The experimental research method is to heat ethanol until it is in the form of steam, then flow it to the burner which will then be given air which is controlled by the mass flow. The research began with the manufacture of magnetic induction from carbon steel wrapped in copper wire. Then testing the fuel by providing a magnetic field before the ethanol fuel enters the burner tip. The magnetic field helps the fuel ionization process, this ionization is needed so that the fuel can easily bind oxygen during the combustion process. If the ionization process goes well then the combustion process becomes more complete. In this ionization process, it will result in the formation of positively charged fuel molecules so that during combustion the combustion process will occur more quickly. The magnetic field will generate Far Infrared waves, which will strengthen the positively charged bonds in the fuel structure due to the ionization process and position these bonds in an orderly manner. This makes it easy for oxygen to react with fuel in the combustion process. With the electric motion force will increase the combustion temperature. The increase in temperature is caused by the process of ionization of the fuel due to the magnetic field generated by the electromotive force. The dynamic electromotive force causes the flame to increase when the current is flowing and decrease when the electric current is cut off. The resulting fire is more transparent, clearer and more visible. The direction of the N-S magnetic field causes the temperature to be higher than the direction of the N-N magnetic field. The magnetic field can affect the burning speed of the ethanol flame. In a poor mixture (ϕ &lt;1) in the presence of magnetic influence, the rate of fire is lower without the influence of a magnetic field, but in a rich mixture (ϕ &gt; 1) in the presence of a magnetic influence, the rate of fire is higher than without the influence of a magnetic field.

Elastic deformation effect on carboxymethyl cellulose water-based (TiO2–Ti6Al4V) hybrid nanoliquid over a stretching sheet with an induced magnetic field

An analysis is carried out to study the two-dimensional stagnant point flow of titanium dioxide -titanium alloy /carboxymethyl cellulose (CMC) water-based hybrid nanoliquid over an expanding surface characterized by the induced magnetic field (IMF). Further, the consideration of thermal buoyancy and the additional nonuniform heat source is involved in the modeling. The intent of this work has significant novelty due to the elastic deformation behavior over a stretching surface. The governing mathematical equations of the problem are reduced to a set of simultaneous ordinary differential equations and are elucidated numerically by employing the Runge-Kutta-Fehlbergs fourth-and-fifth (RKF-45) order process combined with a shooting approach. This article examines the properties of change in parameters on the functions including temperature profiles, induced magnetic field, and velocity profiles of hybrid nanoliquid, shown through graphs. The impact of the Elastic deformation coefficient reduces the temperature where as magnetic field enhance the velocity profile. Magnetic parameter boosts skin friction coefficient with an increase in the buoyancy effect. Momentum profile and induced magnetic field are affected most by the Magnetic Prandtl number

On electromagnetic impacts on the water absorption of vegetable seeds in the sown soil layer

One of the most important tasks for the agro-industrial complex of the Russian Federation is to develop methods for increasing crop seed viability. The way seeds absorb water determines the most important physicochemical processes that ensure their germination and further development of seedlings. There has been studied the impact of the magnetic field, direct and alternating current on the water absorption of cucumber and tomato seeds in the soil layer at a depth of 0.02 m. The surface current density was 0.0022 mA/cm 2, while the magnetic field induction was 3.1 mT. Within 5 hours with an interval of one hour, the seeds were removed and weighed. Direct current (negative/positive) has the greatest impact on the rate of water absorption of cucumber seeds, provided that the positive electrode is in the soil, while the negative one is on the soil surface (20.2% increase). The impact ranks second (12.7% increase), alternating current ranks third (10.1% increase). When using alternating current, the water absorption of tomato seeds increases by 80% higher, while using magnetic impact it increases by 50% than with no impact at all. There have been noted negative rates of water absorption. The results of the work can be used to develop the methods for controlling the rates of water absorption of vegetable seeds with the help of external electrophysical effects.

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.