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Computational analysis has been presented in this paper to discuss one of the approaches of optimum synthesis for the design of magnetics lenses (analytical method). This investigation concentrates on finding the optimum design for single-pole piece magnetics lenses magnetically unsaturated to use in construction magnetics optical systems for transmission electron microscopes (TEM). In this investigation, the same computer program (EOD) program is the geometry of the magnetic lens and the axial magnetic field generated and drawing lines of magnetic flux through the lens. The electron beam's trajectory and objective optical characteristics have been calculated, taking the values of axial magnetics field as input data to calculate the objective length of focal and coefficient of aberrations (spherical and chromatic). In present work has been studied the impact of geometrical parameters for magnetics lenses (axial bore diameter). This investigation's importance is the possibility of determining suitable geometry of the magnetics lenses for benefiting from it in making transmission electron microscopes.

The permanent magnets of the Permanent Magnet Synchronous Generator (PMSG) machine are made up of NdFeB alloy. The Neodymium-iron-boron (NdFeB) permanent magnets’ overall magnetic energy or energy product limits the maximum magnetic flux density value that can be achieved in the PMSG configuration. The generator shaft is made of stainless steel and has an electrical conductivity σ = 1.35 MS/m and relative permeability μr = 1. The flux is not well concentrated without optimizing the geometry of the NdFeB permanent magnets and rotoric slot opening. Therefore, optimization of NdFeB permanent magnet geometry and rotoric slot opening will maximize the linkage flux and mutual flux components and minimize leakage flux components of Permanent magnet synchronous generator. In this current research work, the goal is to maximize mutual flux and linkage flux while minimizing PMSG's leakage flux components at the same time by optimization of geometrical parameters of Permanent magnet synchronous generator using different optimization algorithms. In this work, finite element method is mapped by Radial Basis Function (RBF) neural network so that for any value of NdFeB permanent magnet length or rotoric slot opening, magnetic flux could be estimated immediately. In this present research work, an attempt has been made to determine the optimal values of geometric parameters, length of the NdFeB permanent magnet bm and slot opening of rotor bo for which the linkage flux and mutual flux are maximized and leakage flux is minimized. The values of permanent magnet length bm obtained using dynamic particle swarm optimization (DYPSO) and self-adaptive particle swarm optimization (ADPSO) are 28.5523 mm and 28.5524 mm respectively. The values of rotoric slot opening bo obtained using dynamic PSO and self-adaptive PSO are 18.587 mm and 18.587 mm respectively.

The Magnetically Impelled Arc Butt (MIAB) welding process uses a rotating arc as its heat source and is known as an efficient method for tube welding. Interaction of external magnetic field and induced magnetic flux results in the creation of Lorentz force along peripheral edges of tubes. The circumferential arc rotation helps in the uniform heating of faying surfaces. After sufficient melting, faying surfaces are pressed against each other for weld formation. This paper aims at studying the notch tensile properties of T11 tubes welded by MIAB welding. In MIAB welded T11 steel tubes various Thermo-Mechanically Affected Zones (TMAZ) are formed as an effect of heat and pressure during welding. Tensile properties of all these TMAZs are different due to varying microstructures. Therefore notched tension testing was carried out to compare the properties of various zones in welded T11 tubes. All TMAZs show higher notch ductility with Notch Strength Ratio (NSR) greater than one. In comparison to the base metal, all TMAZs except TMAZ III display no loss in notch strength. The presence of granular bainite in TMAZ III causes lower notch strength with a Normalized Notch strength (NTSN) ratio less than unity.

The virtual equivalent line method for the axial-flux permanent magnet eddy current coupler is proposed in this paper to solve the problem of the difference in the length of the magnetic flux path between the inner radius and outer radius of the axial section of the radial centerline of the magnetic pole. Different from the average radius equivalent method, the virtual equivalent line method adopts the function of variable pole radius instead of the fixed average radius, which establishes a uniform analytical expression of the air gap flux density and can accurately calculate the magnetic flux density at any magnetic pole radius. Furthermore, the end-effect compensation function is obtained. In order to investigate the effectiveness of the proposed method, the results calculated by the analytical method are compared with the finite element method. It is shown that the novel method proposed in this paper is highly consistent with the air gap flux density calculated by the finite element method.

Power system (PS) requires new flexible AC transmission systems, new solutions for voltage instability problems with simple design and fast response and its equipment, should allow reactive control, short-circuit capacity, dynamic behavior, flexibility and more efficiency control for the grid associated to reliability and security. This research develops a magnetically controlled reactor (MCR) design for a weak system. A methodology for design is proposed with a primary winding connected to the PS and the secondary winding connected to voltage control, the magnetic flux is modified by the direct current, therefore, the equivalent impedance is modified. This proposal is validated in a case study for Peruvian grid with low short circuit and reactive power. Our findings are: (i) A dynamic model in failure condition regarding the error signal. (ii) The MCR can assume reactive compensation in the unsaturated and saturated regions, (iii) it can be scalable into several stages with banks.

Surface magnetic configurations and electromagnetic responding behaviors can be efficiently modulated by controlling the growth of magnetic materials, which has always been a huge challenge. Here, an in situ orientation growth strategy is developed to build a micron scale Fe3O4–Fe3O4@C heterojunction via applying Kirkendall diffusion to the orientation growth process. Undergoing precipitation and phase transition process, the oriented Fe3O4 octahedron tightly rooted in anisotropy Fe3O4@C body, constructing various magnetic configurations and enhancing stray magnetic field intensity. As-synthesized magnetic-dielectric microspheres exhibited excellent energy conversion capacity toward electromagnetic wave, including strong reflection loss (RL: 40.8 dB, 2.0 mm) and ultra-wide absorption region (∼11.04 GHz, ∼69% of the tested frequency). Essentially, cross-space magnetic coupling enlarges the responding region beyond the material itself and strengthens electromagnetic wave disputation. Local charge density distribution around the grain boundary plays the key role in forming the enhanced interfacial polarization, which is characterized by the off-axis electronic holography. More importantly, the dynamic response mechanism was firstly observed under an applied magnetic field. Changing magnetic configurations induce the rearrangement of magnetic flux distribution, providing the internal magnetic feedback. Above-mentioned dielectric and magnetic properties of Fe3O4–Fe3O4@C composites make a breakthrough understanding toward the energy conversion mechanisms.

This paper presents the modeling, controller design and testing of the integrated permanent magnet toroidal motor drive. As one kind of direct-drive composite motor drive, the integration and configuration for permanent magnet toroidal motor are presented. Based on its special rotor structure, the magnetic flux linkages of the worm stator windings are deduced with its structural and kinematic parameters. The voltage equations and electromagnetic torque in rotary two-phase coordinate are presented. The dynamic machine model for permanent magnet toroidal motor drive is established with nonlinear time-varying electromagnetic parameters, which include inductances and differential information. Then, the dynamic performance with periodic fluctuation is analyzed. Based on the effect analysis for the dynamic response, the electromagnetic torque model of permanent magnet toroidal motor drive is properly simplified. In order to improve the output performance of toroidal motor drive, a terminal sliding surface is introduced in the controller design to accelerate the response speed, and meanwhile, the sliding mode observer is proposed to estimate the angular speed of the rotor in the feedback loop to achieve better tracking performance. The foundation test of inductance was conducted and demonstrates the validity of the machine model. The simulation results show that the proposed control strategy can significantly improve the dynamic behavior and robustness of the permanent magnet toroidal motor drive system.

Ferrite Encumbered inductive coupling-based energy transmission is interestingly being investigated both theoretically and experimentally as an alternative technique of delivering power through human skin and body for wireless excitation of implantable electronic devices. In the explored system, to enhance the efficiency, the magnetic flux produced by the transmitting coil can be improved focused through the ferrite loaded printed receiving coil by cautious symmetrical placement of ferrite materials. The properties of ferrites include high magnetic permeability and high electrical resistance. In this paper, a ferrite configuration is estimated using Finite Element Method, and an efficient model is nominated for construction and laboratory testing. The proposed technique entails an energy transfer efficiency of ∼48.2% at maximum output power of 248 mW and resonant frequency of 120 kHz over a separation gap of 3 cm. The real-time body temperature of human has been recorded through the energized temperature sensor and corroborated with a calibrated system which ensures the precision of the developed prototype system. The real time data collected in the laboratory are in good agreement with the simulation results, which specify that the laboratory physical prototype and circuit closely followed to the physical and electrical parameters of the simulation. The ferrite loaded resonant inductive coupling technique is considered as a feasible and supportive substitute to the conventional technique for implantable electronic sensors.

In this paper, we investigate the analogue effect to the Aharonov-Bohm effect for bound states in a relativistic quantum system described by the Klein-Gordon oscillator in the cosmic string space-time with a spacelike dislocation. We assume the topological defects have an internal magnetic flux and then analyze the effect on the relativistic energy eigenvalue subject to a Cornell-type potential and subsequently with a Coulomb-type potential. We show the presence of various potential parameters, the torsion parameter as well the cosmic string modify the energy spectrum.

Purpose This study aims to investigate the impact of the cavity on the sinus wall dose by comparing dose distributions with and without the sinus under magnetic fields using Monte Carlo calculations. Methods A water phantom containing a sinus cavity (Empty) was created, and dose distributions were calculated for 1, 2, and 4 irradiation fields with 6 MV photons. The sinus in the phantom was then filled with water (Full), and the dose distributions were calculated again. The sinus was set to cubes of 2 cm and 4 cm. The magnetic field was applied to the transverse and inline direction under the magnetic flux densities of 0 T, 0.35 T, 0.5 T, 1.0 T, and 1.5 T. The dose distributions were analyzed by the dose difference, dose volume histogram, and D2 with sinus wall thicknesses of 1 and 5 mm. Results D2 in the “Empty” sinus wall under transverse magnetic fields for the 1-field and 4-field cases was 51.9% higher and 3.7% lower than that in the “Full” sinus wall at 1.5 T, respectively. Meanwhile, D2 in the Empty sinus wall under inline magnetic fields for 1-field and 4-fields was 2.3% and 2.6% lower than that in the “Full” sinus at B = 0 T, respectively, whereas D2 was 0.9% and 0.7% larger at 1.0 T, respectively. Conclusions The impact of the cavity on the sinus wall dose depends on the magnetic flux density, direction of the magnetic field and irradiation beam, and number of irradiation fields.

The heart is the essential, yet complex, component of the human cardiovascular system. In the past few decades, researchers have taken giant steps toward better understanding of the cardiac system and there have been proposed some mathematical models to describe the heart's function. In this paper, a new Fitzhugh-Nagumo neuron (FNN) model is proposed to model the electrical activity of the heart in which the effect of magnetic flux is considered. Magnetic field can greatly affect the heart's function. The dynamical analyses of the model, including quantitative assessment of the system's equilibria and its stability, phase portraits analysis, bifurcation and Lyapunov exponents analysis, and basin of attraction analysis, are carried out. In addition, a model of cardiac tissue is designed to study the electrical spatiotemporal activity of heart tissue under the electromagnetic effects. Our numerical simulations confirm that the electromagnetic excitation can change the normal rhythm of the heart. It can initiate the reentrant excitations leading to emergence of spiral seeds. This study highlights the role of electromagnetic induction in dynamical instability of the action potential duration, and thus the chaotic dynamics in the cardiac tissue.

An axial flux permanent magnet (AFPM) generator is known to be a good candidate for both low and high-speed application. In this paper, a new design of fully coreless multi-stator multi-rotor (MSMR) AFPM generator has been presented with conventional and Halbach magnet arrangement combined with an ironless (epoxy) rotor. For MSMR topology of AFPM machine, back iron is still present in the middle rotor and to maintain the same distribution of magnetic flux, magnets are using on both side of the middle rotor. This paper suggests replacing the middle iron rotors with a single epoxy rotor which reduces the weight of the machine, hence increase power density. On the other hand, for the elimination of iron and magnets in the middle rotor, conventional magnet arrays are used to maintain a continuous flux path. In addition, Halbach array is adopted on the external epoxy rotor to reduce flux leakage on the external sides of the machine. The performance of the proposed generator is investigated in terms of voltage, current, power, power density, and torque ripple. The analytical design approach is first presented and subsequently validated using ANSYS Maxwell® electromagnetic finite element analysis (FEA) software. It is found that a fully coreless MSMR AFPM generator with conventional and Halbach magnet arrays gives higher power density and lower torque ripple with a reduced axial length which is favorable in wind power and pico-hydro applications.

Surface quality is most desirable for high speed machines and reciprocating parts where friction must be minimized. Surface quality is deteriorated during different machining, casting and forming operations which must be retained during finishing of product. Researchers have faced many challenges to achieve nano-level finish using conventional finishing processes. Thus, they have focused on advanced finishing process such as magnetic abrasive honing which yield ultra-smooth surface. In present research work, optimization of process parameters is performed to enhance the surface finish during honing process. The impact of rotations, magnetic flux and processing time has been studied on percentage change in surface roughness. Ferrous oxide and iron abrasive particles are used during processing. A non-linear equation has been developed between independent and dependent variables using regression analysis. Genetic algorithm is applied to optimize the objective equation which suggested the significance of rotations which are directly proportional to output.

An algorithm of adaptive estimation of the magnetic flux for the non-salient permanent magnet synchronous motor (PMSM) for the case when measurable electrical signals are corrupted by a constant offset is presented. A new nonlinear parameterization of the electric drive model based on dynamical regressor extension and mixing (DREM) procedure is proposed. Due to this parameterization the problem of flux estimation is translated to the auxiliary task of identification of unknown constant parameters related to measurement errors. It is proved that when both current and voltage measurements are biased the proposed algorithm ensures convergence of the flux observation error to a bounded set. At the same time the position error converges to zero. The observer provides global exponential convergence if the corresponding regression function satisfies the persistent excitation condition. If the regression function is not square integrable the global asymptotic convergence is ensured. In comparison with known analogues this paper gives a constructive way of the flux reconstruction for a nonsalient PMSM with guaranteed performance (low oscillation, convergence rate regulation) and, from other hand, a straightforwardly easy implementation of the proposed observer to embedded systems.

Memristor’s electrical behavior can be defined as inter-relationship between electric charge and magnetic flux. Memristor exhibit memory characteristics. Its present state resistance depends on the amount of charge passed through it in particular direction previously. This varying resistance property can be used as non-volatile memory property. Memristor have very steep off to on transitions with a large on-off resistance ratio. A device with more control terminal offer superior control over its characteristics than two-terminal devices. The unique characteristics of memristor along with long retention time and low complex device geometry make them ideal to model them as three-terminal devices. The prime objective of this paper is to model a drift based three terminal memristive (Gated Memristor) device that possess same memory, current characteristics and pinched hysteresis effect that of a two-terminal device. Further, the modeled device can be used to realize various novel digital and analog circuits. Device is modeled using Verilog-A language and simulated using Cadence Virtuoso environment.

One of the main power stations in Zimbabwe has its generators located 100m underground. Elevators that used to carry people to the underground plant are not functional anymore due to old age and corrosion of the hoist way blade and guide rails. A system with an electromagnet actuator attached to the elevator car and its core shaped in the form of the letter ‘E’ used for coupling the magnetic flux between the coil and the hoist way rail blades was designed. Pairs of coils are wound on the actuator core in a manner that produces both side-to-side and front-to-back forces that are controlled by adjusting the current being supplied to the coils. The electromagnets fixed to the car supply the force of attraction between the actuator and guide rail, which then keep the car suspended; the motor is used to provide a driving force for the up and down movement of the car. The research satisfied the 9th Sustainable Development Goal of 2015, thereby contributing towards sustainability.

The surface finish is an important characteristic of the machined surface which is influenced by wear, friction and rotation of the mechanical component. In this work, the effect of different range of process parameters like working gap, rotational speed and machining time on magnetic-abrasive machining process are analyzed. The finishing action is done on mild steel cylindrical work piece. Moreover, the optimization of the best parameter at a particular range of electromagnetic flux for surface roughness of mild steel tube is done by Taguchi method. For surface roughness, the working gap is significant, followed by machining time and rotational speed, and obtained the optimum value of surface roughness (Ra) is 1.489 µm at 35 mm working gap, 430 rpm rotational speed and 2 min. machining time.

In recent years, due to the digitization of the electrical devices electric load demand has been increased. Power security and stabilization are the other two challenges which necessitate the need of electrical energy storage. Along with the technological constraints, economical and environmental issues are the other challenges in the development of energy storage technologies. Fast response and high energy density features are the two key points due to which Superconducting Magnetic Energy Storage (SMES) Devices can work efficiently while stabilizing the power grid. Two types of geometrical combinations have been utilized in the expansion of SMES devices till today; solenoidal and toroidal. It has been found that the solenoidal arrangement is easier to fabricate and provides efficient approach to handle stresses produced by Lorentz forces. This work represents the development of 2.5MJ SMES solenoidal Magnet using 2G (SuperPower, YBCO having Tc=90K @ 0T) HTS tape. The effect of the operating current (passing through a single superconducting tape) has been evaluated. A reference magnetic flux of 3.5T has been considered in designing of HTS SMES. It has been found that the parallel fields for solenoidal magnet are large as compared to perpendicular fields which results into large magnitudes of Lorentz forces acting on HTS tape which may leading to structural instabilities and can cause failure. It has been concluded that higher currents can be used in order to lower down the total length of the superconductor as it can reduce the overall cost of the device

Micro motors in the robotic application have the advantage of lightweight, small size, more reliable and highly efficient. The objective of this study is to improve the speed characteristics of micro PMBLDC for surgical robot applications. In this paper, the micro PMBLDC for various configurations of inter pole is developed to obtain the desired torque and magnetic flux. The PID controller and fuzzy logic controller using ANFIS is proposed to regulate the speed response of the BLDC motor. The combination of PID and fuzzy logic in the closed-loop gives a steady-state error of 2.376%, and the use of a PID controller alone gives a steady-state error of 12.5%. With the proposed design of the controller for BLDC motor, the desired speed with lesser steady-state error obtained for surgical stapler application.

The higher magnetic levitation force and related stiffness values are very important for Maglev and magnetic bearing applications. Also, larger superconducting surface area is needed for continuous and larger magnetic mediums with different geometries and dimensions in real scale industrial applications of superconducting systems. In this study, the cylindrical YBCO superconductors were fabricated by top−seeded melt growth (TSMG) method in single and two−seeded forms with different seed distances and then the magnetic force and stiffness measurements were carried out by three axes magnetic force measurement system in different cooling heights (CH) of 20 mm and 75 mm. Additionally, a new analytical method, based on the magnetic dipole approximation, is proposed to calculate the levitation force in this study, named as Modified Advanced Frozen Image Method (MAFI), since although the Advanced Frozen Image Method in literature can calculate the levitation force with hysteresis, this method does not include the size effect of the superconductor. In the experimental studies, it is seen that the maximum levitation force values obtained by PMG with three PMs (named PMG−1) are more than two times higher than that of obtained with single PM for all samples with different distance of seeds, because of the higher magnetic flux distribution of related PMG arrangement than the single PM. In addition, the maximum magnetic levitation force value firstly increased and then decreased due to current coupling effect weakness by increasing distance of seeds. The calculated analytical levitation force results are not compatible with the experimental results without current coupling effect, but a well agreement is observed when the current coupling effect is taken into account in calculations. Also the MAFI method was tested with different dimensions of superconductors and the obtained results indicated the success of the proposed method. The maximum levitation force values obtained with MAFI method increased with increasing dimensions of HTS and PMs. Thus, one can say that the MAFI method is useful for the levitation force calculations between multi−seeded superconductors and PMGs with different dimensions and for different CHs. As a result, the analytical levitation force values obtained with the MAFI method are agree with the experimental levitation force sufficiently and this method can give fast calculation results without any divergence problem. This method can be thought as an alternative to the numerical calculation methods, having serious divergence problems for much amount and bigger size superconducting samples, therefore it will be useful to clarify bulk superconducting properties as supporter to the experimental studies.

We propose a non-resonant finger-triggered electromagnetic energy harvester (EMEH) using multiple gear modules and an array of disc Halbach magnets, which can generate significant voltage and power under low input-frequency vibrations. The proposed EMEH converts the applied low frequencies into higher frequencies using a multiplying gear module and forwards the linear excitation to a rotational module by gear parts. The multiplying gear module was used for increasing the speed of magnet motion. In the energy generation part, an array of disc Halbach magnets were used for concentrating the magnetic flux toward the coils. The proposed energy harvester generated an open-circuit voltage of 1.39 V at an average power of 7.68 mW, with an optimal load of 36 Ω at an input frequency of 3 Hz. The prototype harvester offers a power density of 0.833 mWcm−3, which is much higher than those of recently reported EMEHs. We demonstrate wearable and portable electronics such as a stopwatch and pedometer-based on finger triggering. This study presents an important step toward low-frequency-vibration-powered devices for portable smart electronic applications and is expected to be widely applicable.

Many countries have recently become interested in the deployment of cyber-physical systems (CPS) in industry and society for sustainable development. A CPS comprises a data acquisition function, a data storage function, and a network to transfer data. The move to deploy CPS in society makes it necessary to increase their energy efficiency and to find new energy sources. To overcome these energy-related issues, in this research we investigated the possibility of integrating data acquisition sensors with a recently developed energy harvesting system that combines the magnetic phase transition resulting from changes in temperature, and electromagnetic induction resulting from changes in magnetic flux. The proposed system can provide wireless temperature or velocity sensors that directly measure electromotive forces generated by a solenoid following Faraday's law without any additional energy input. Our proposed energy harvesting sensors have the potential to contribute significantly to the development of CPS in the near future.

This research paper presents a novel technique to determine the required value of capacitor used in a capacitor-run single phase induction motor. Dynamic analysis of main winding and auxiliary winding currents are performed and the electromagnetic flux revolving in the stator-rotor air gap is studied. In capacitor-run single phase induction motors, the most suitable capacitor is one that produces an electromagnetic flux that has a uniform trajectory (distribution) along the air gap. The novel technique presented in this research paper is the application of roundness algorithm to determine the most uniform trajectory of electromagnetic flux produced by varying auxiliary winding capacitors. The value of capacitance thus found from the proposed technique is compared with the motor manufacturer recommended capacitance. The agreement of the comparison validates the usefulness of the proposed technique.

The inorganic-organic multiferroic magnetoelectric materials possess extensive research interest for an application point of view considering the flexible magnetoelectric devices. The ferroelectric polymer based poly(vinylidene fluoride) - Zn 0.2 Co 0.8 Fe 2 O 4 magnetoelectric flexible having self-standing nanocomposite film has been prepared through the low temperature chemical process and followed by the solution casting technique. The structural characterizations have been carried out by X-ray diffraction technique. The surface morphology of this film is analysed using atomic force microscopic topography. The electrical properties of the flexible film have been observed with an induced effect of confirmable visible light, where the magnetic field produces a significant influence. The combined effect of the visible light and the magnetic flux is controlling the electrical properties of the film. This film is showing the resistive switching effect with time and the radiation of light energy at room temperature. The magnetoelectric coupling coefficient of the flexible film has been measured as a function of an applied magnetic field at different experimental configurations at room temperature. The attempted research work provides an information about the visible light and magnetic field induced effects of the magnetoelectric material. However, it may be extended for an application purpose to develop the multiferroic magnetoelectric based devices.

When the equipment which is related to safety or important to power production is installed in nuclear power plant units (NPPs), verification of equipment Electromagnetic Susceptibility (EMS) must be performed. The low-frequency radiated magnetic field susceptibility (RS101) test is one of the EMS tests specified in U.S NRC (Nuclear Regulatory Commission) Regulatory Guide (RG) 1.180 revision 1. The RS101 test verifies the ability of equipment installed in close proximity to sources of large radiated magnetic fields to withstand them. However, RG 1.180 revision 1 allows for an exemption of the low-frequency radiated magnetic susceptibility (RS101) test if the safety–related equipment will not be installed in areas with strong sources of magnetic fields. There is no specific exemption criterion in RG 1.180 revision 1. EPRI TR-102323 revision 4 specifically provides a guide that the low-frequency radiated magnetic field susceptibility (RS101) test can be conservatively exempted for equipment installed at least 1 m away from the sources of large magnetic fields (>300 A/m). But there is no exemption criterion for equipment installed within 1 m of the sources of smaller magnetic fields (

Electrospinning technology is taken as the most versatile process to generate continuous nanofibers. However, effects should be taken to achieve better understanding and precisely control the actual mechanics in the formation of nanofibers through better system design. In this article, the diameter and the deposition area of the as-prepared nanofibers can be controlled by added helix tube which can provide external electric-magnetic field. The spinning process can be controlled employing a magnetic flux (B) analytical model which is based on the magnetic field calculation model of the solution and the electrostatic charge repulsion in the jet. This method includes the thermo-mechanical properties based on as-prepared electrospun nanofiber films and the capability of tribology-mechanical and mathematical physics. A novel investigation of the whole output increase at per unit spinning area is presented in this article to describe the whipping instability which is an important feature of the Taylor Cone phenomenon. The present design and process for electrospinning are based on a solution differential calculus, which a single stainless steel spinning nozzle can generate multi-squirt flow. With the purpose of providing useful jet initial behaviour design for the further technology applications, we attempt to set up a differential calculus method with evenly distributed circumferential electric field, yet giving more design guidance to produce controllable nanofibers through magnetic-field-assisted electrospinning technology.

With the aim of understanding the photospheric magnetic field properties of active regions (ARs) that produce M-class or greater flares, physical magnetic parameters of ARs provided by the Space-weather HMI Active Region Patches (SHARP) are examined. A total of 223 flares are collected in 83 ARs, including 31 X- and 192 M-class flares. In this study, twelve SHARP parameters are analyzed, which are the sums of various physical quantities (e.g., magnetic flux, magnetic free energy density, vertical current, current helicity, shear angle, and Lorentz force). For X- and M-class flares, good correlation coefficients ( ≳ 0.90) are obtained among the seven magnetic parameters, namely, total unsigned quantities of (1) magnetic flux, (2) vertical current, (3) current helicity, and (4) flux near polarity inversion line, as well as (5) total photospheric magnetic free energy density, (6) total magnitude of Lorentz force (TOTBSQ), and (7) area of AR. A threshold for low bound is estimated for each of the seven magnetic parameters based on X-class flares. Only ∼5% of M-flares occur below the estimated thresholds. A time difference ( T SF ) is calculated between the time when all the magnetic parameter thresholds but TOTBSQ are met ( T 1 ) and the time when the flare starts. The TOTBSQ is excluded in the T 1 calculation because its value is often missing in the interval of interest. Results show that (1) ∼77% of X-flares occur within 7 days after T 1 , with an occurrence peak at T SF = 2 (∼20% probability), (2) ∼78% of M-flares also occur within 7 days after T 1 , with an occurrence peak at T SF = 4 (∼20% probability), and (3) no major flare occurs after T SF = 11 . It is found that the GOES soft X-ray peak flux has a very weak relationship with the magnetic free energy density. This weak relationship can be interpreted in terms of the energy partition in a flare. In conclusion, the obtained seven thresholds will be useful for monitoring an AR that has a high potential to produce an M- or X-class flare.

In this paper, a broadband closed-form expression for the parasitic inductance of Through-X Vias (TXVs) with a frequency up to 100 GHz is proposed. The rigorous formulas related to the geometrical parameters are derived considering the proximity effect and the skin effect. The proposed model can accurately reflect the change in inductance caused by magnetic flux variation at high frequency. The inductance model is verified by comparing with the 3-D full-wave electromagnetic solver High Frequency Simulator Structure (HFSS) in whole frequency range considered. The proposed model and HFSS results show accordance with each other over large radius range, with a maximum error of 4.6%.

The competitive effect between electric and magnetic flux couplings is used, in the context of modulational instability, to describe the collective dynamics in a modified Hindmarsh–Rose neural networks. The multiple-scale expansion is utilized to reduce the system to a nonlinear differential-difference equation, whose plane wave solutions are found to be unstable for some values of parameters. Particular interest is given to the influence of changing both the electric and magnetic coupling strengths, and confirmation of analytical results is given via numerical integration of the generic Hindmarsh–Rose model. The model presents a rich variety of spatiotemporal patterns propagating in the network, as the result of the interplay between nonlinear and dispersive effects. The electromagnetic induction appears to be responsible for regular bursting patterns and synchronous states in the network. With increasing the electric coupling, full synchronization is difficult to realize and irregular spatiotemporal patterns of action potentials are predominant.

Two-dimensional stagnation point flow of single and multi walls carbon nanotubes towards a stretching sheet is addressed. Induced magnetic field is considered. Homogeneous-heterogeneous reactions is accounted. Both SWCNTs (single wall) and MWCNTs (multi wall) are considered as nanoparticles whereas water and kerosene oil are considered as base liquid. Xue’s model is used for the physical characteristics of density, specific heat and thermal conductivity. The consequences of present work is to investigate impact of induced magnetic field in quartic chemical reactive stagnation point flow with influence of SWCNTs (single wall) and MWCNTs (multi wall). Dimensionless variables are introduced to model physical problem mathematically. Equations are then solved numerically with the help of Built-in-Shooting technique for non-dimensional induced magnetic field, velocity, concentration and temperature. The impacts of different dimensionless flow variables like stretching rate ratio parameter, magnetic parameter, thermal radiation, reciprocal magnetic Prandtl number, homogeneous reaction and heterogeneous reactions parameters and heat generation parameter are depicted through graphs. Computational analysis for surface drag force and Nusselt number are tabulated to examine the behaviors at stretched sheet. It is noticed that induced magnetic field enhances via higher nanoparticles volumetric fraction. Furthermore, multi (MWCNTs) has more contribution in enhancing induced magnetic field when compared with single (SWCNTs).

Anisotropic magnetoresistive (AMR) sensors have long been used for specific industrial applications. Their field detection sensitivity can be improved using magnetic flux concentrators to amplify the magnetic field strength sensed at the sensor. We report on the design and fabrication of a micrometer-size meander AMR bridge sensor with an effective AMR branch length of 150. This sensor geometry has enabled us to achieve a magnetic sensitivity as high as 1.25 mV/Oe (or 0.45 mV/V/Oe), which is an enhancement by a factor of about 300 compared to conventional AMR thin film-based sensors. Our study paves a new pathway for the design and application of geomagnetic devices. Keywords: Magnetic sensor, Anisotropic magnetoresistance, Wheatstone bridge sensor, Geomagnetic devices, Permalloy

Because the gaps between plasma-facing components in fusion devices are comparable in size to the ion Larmor radius (of the order of 1 mm), magnetic field line tracing, the so-called "optical approximation", cannot accurately predict the fine scale heat load distribution around the gap edges. Finite Larmor radius effects dominate ion deposition. The poloidal component of the ion flux striking the surface is always in the diamagnetic/EXB drift direction, meaning that ions preferentially load one side of the gap. Usually electrons can be described optically due to their smaller Larmor radius. Depending on the local inclination of magnetic flux surfaces, it is possible that ions and electrons wet the same side of the gap, or opposite sides. Two-dimensional particle-in-cell simulations and dedicated experiments performed in the COMPASS tokamak are used to better understand processes responsible for plasma deposition on the sides of toroidal gaps between castellated plasma-facing components in tokamaks. The different contributions of the total incoming flux along a toroidal gap have been observed experimentally for the first time in COMPASS. These experimental results confirm the model predictions, demonstrating that in specific cases the heat deposition does not necessarily follow the optical approximation. The role played by electric fields in the deposition pattern is marginal, contrary to local non-ambipolarity that can change the asymmetrical plasma deposition from one side of the toroidal gap to the other.

In this paper, we describe an approach to achieve fusion which employs a hybrid of elements from the traditional magnetic and inertial fusion concepts, called magneto-inertial fusion (MIF). The reduction in thermal-conduction losses in the hot spot of an imploding target that has trapped and amplified a pre-seeded magnetic flux leads to increased hot-spot temperatures at lower implosion velocities than required in conventional ICF. The use of this method is due to the use of a magnetic field and the reduction of the primary laser energy for compression fuel can be economically better in comparison with the previous two methods. In this work, the energy losses from the target including bremsstrahlung, cyclotron and electron thermal conduction on the ignition temperature for a simulated fuel pellet,(D/Tx/3Hey) in magneto-inertial fusion have been studied, then gain and temperature ignition of fusion system have been computed in this condition.

Physical realizations of non-standard singular self-adjoint extensions for one-dimensional Schr\"odinger operator in terms of the mass-jump are considered. It is shown that corresponding boundary conditions can be realized for the Hamiltonian with the position-dependent effective mass in two qualitatively different profiles of the effective mass inhomogeneity: the mass-jump and the mass-bump. The existence of quantized magnetic flux in a case of the mass-jump is proven by explicit demonstration of the Zeeman-like splitting for states with the opposite projections of angular momentum., Comment: 11 pages, 7 figures

The earth has abundant water resources, and efficient harvesting of energy from waves is always a research hotspot. In this paper, we fabricate a box-like triboelectric-electromagnetic hybrid nanogenerator for harvesting water wave energy, which is composed of the triboelectric nanogenerator (TENG) and the electromagnetic generator (EMG). In the case of TENG, the contact and separation between the aluminum film-coated PMMA cylinder and the silicone film covered interdigitated Ag electrodes is formed by ocean waves. In the case of EMG, a rolling magnetic ball is placed on the four coils to generate magnetic flux changes, thus generating electricity. Several experiments are conducted to validate the availability. Experimental results show that the instantaneous maximum output power of TENG is 0.08 mW at a load of 100 MΩ, and the instantaneous maximum output power of EMG is 14.9 mW at a load of 1 kΩ. The hybrid nanogenerator can light up 60 LEDs at the same time. After storing energy in the capacitor, the output DC signal can provide a continuous energy supply with the temperature sensor. More important, the nanogenerator can power the wireless acoustic sensing system.

While the Coronal Mass Ejections (CMEs) without associated flares are known to accelerate and decelerate being moderated by the Lorentz force, gravity and the drag force due to solar wind, the flare association is known to prolong the acceleration. However, with or without the flare association, a significant proportion of slow CMEs decelerate and a similar proportion of fast CMEs accelerate. In the case of accelerating CMEs, various parameters of CMEs such as the mass, angular width etc. show good correlation and this improves with flare association. When the flares and CMEs are associated, there is apparently a division of energy between the flares and the CMEs. It is also known that the magnetic flux spanned by the flare arcade and ribbons after flare maximum, roughly equals the magnetic flux content of the CME and their ratio could be between one and two. The magnetic flux content of the CME can be estimated from the final angular width of the CME. Hence, we suggest that the CMEs experience net acceleration when the different parameters of CMEs such as angular width, mass etc. are correlated and when the CME parameters are correlated with flare duration and peak flux. The absence of the same may lead to CMEs experience net deceleration.

Fluctuation of membrane potential occurs when the concentration of ions, e.g., Calcium, Potassium, Sodium, in the cell is changed. When external electric stimulus beyond threshold is applied, action potential can be induced to predict the changes in distribution density of ions, which can also trigger time-varying electric field and magnetic field. For example, each static charge can induce spatial distribution of electric field while any moving charge can generate distribution of magnetic field. In this paper, a neuron is considered as a complex charged body and the effect of electromagnetic field is considered to build a new neuron model, which magnetic flux and charges is used to describe the variation of magnetic field and electromagnetic induction, electric field, respectively. The physical neuron model is then described by dimensionless dynamical system after scale transformation and then is verified on analog circuit platform. Nonlinear analysis is practiced on this new neuron model and external electromagnetic radiation is applied to detect the mode transition and response in neuronal activities. The electrical activities can be modulated when the band of electromagnetic radiations is adjusted. It can throw light on investigation of neurodynamics and experimental practice in neural circuits.

We investigate the Aharonov-Bohm (AB) effect in the parallel double-quantum-dot structure, by introducing an additional s-wave superconductor to couple to the quantum dots. It is found that the AB oscillation of the electron tunneling is different from the superconductor-absent result. Meawhile, the local and crossed Andreev reflections exhibit their special oscillation behaviors, with the change of the local magnetic flux. This means that the AB effect plays an important role in manipulating the complicated quantum transport through this system. We believe that this work can be helpful for understanding the AB oscillation in the presence of Andreev reflection processes.

In this paper, Multi-Objective Optimization (MOO) techniques namely: Weighted Sum Method (WSM), Multi Objective Genetic Algorithm (MOGA) and Niched Pareto Genetic Algorithm (NPGA) are proposed for the design optimization and analysis of magnetic flux distribution for a slotless permanent magnet Brushless DC (BLDC) motor. The sensitivity analysis is carried out to identify the design variables of BLDC motor which influence the objective function. The objective functions are conflicting in nature (maximization of output torque and minimization of total volume and losses), hence, are optimized simultaneously by means of MOO algorithms. The proposed MOOs account for four kinds of design variables namely: rotor radius, stator/ rotor axial length, magnet thickness and winding thickness simultaneously to maximize the output torque and to reduce the total volume and total power loss. The conventional MOO such as WSM gives single pareto optimal solution. However, the proposed MOGA and NPGA algorithms create accurate and well-distributed pareto front set with few function evaluations. The performances of the three MOOs are evaluated and compared using the four performance metrics namely: Hyper Volume (HV), Generational Distance (GD), Inverted Generational Distance (IGD) and Spread. From the comparison, it is observed that NPGA gives better results. Using the design parameter obtained from NPGA, the magnetic flux distribution analysis of the BLDC motor is carried out to analyze variation of flux distribution in the different parts of the motor. The results thus obtained are compared with those obtained through Partial differential equation and single objective GA optimization. The detailed thermal analysis is also carried out to analyze the thermal behavior at different parts of the machine for different working conditions in the continuous operation mode and hence, the results obtained are compared with single objective GA optimization. The advantages of MOOs in the design optimization of slotless permanent magnet BLDC motor are highlighted.

High permeability and high saturation magnetization are two key attributes to strong microwave absorption for magnetic loss composites, which depend on the chemical composition, particle size, surface profile, fabrication method, etc. However, it is still a challenge to understand the influences of these properties on micro magnetic behaviors to manipulate microwave absorption performances. In this study, magnetic absorbers with spherical and flaky shapes were adapted to investigate the influences of morphology on magnetic properties via off-axis electron holography. Stray magnetic flux lines were visualized to validate the difference in the forms of magnetic incorporation among spherical and flaked-shaped metallic particles, which then results in reflection loss (RL) up to −53 dB for the flakes and absorption (>99%) bandwidth up to 3 GHz for the spherical types. The micro-field detection using the powerful technique of off-axis electron holography sheds new light on the understanding about intrinsic magnetic micro behaviors for metallic composites.

Alternating Current Potential Drop (ACPD) measurements are routinely used for monitoring crack length in laboratory based fatigue tests, and so measurements will be taken on components which are exposed to cyclic dynamic stresses. It has been empirically observed that cyclic stresses cause a strong increase (above 10% is shown in this paper) in measured resistance that is both AC inspection frequency and loading frequency dependent. The excess resistance will result in erroneous measurements; this paper investigates the cause and provides recommendations to limit the influence. Applied stresses influence ACPD measurements through the magnetoelastic effect; elastic strain induces magnetization in ferromagnetic materials, which in turn influences the magnetic permeability and therefore skin depth. Further, it has recently been realised that cyclic magnetization results in a frequency dependent concentration of the magnetic flux at the surface of the component, and consequently a non-uniform spatial distribution of magnetic permeability. In this study it is found that the interaction between the non-uniform spatial distribution of both the current density and magnetic permeability results in significant non-linear modulation of the measurement signal. A combination of finite element simulations and experimental results are used to explore this phenomenon.

The torque transmission and angular speed change in machine mechanisms are provided by mechanical gear systems. Recent advances in magnetic system designs, developments in quality of the permanent magnetic and ferromagnetic materials led to possibilities of replacing magnetic gears with their mechanical counterparts. Magnetic gears are free from damages during the overloaded operation since they have no physical contact. However, the torque density in magnetic gears is lower compared to mechanical gears due to the limited magnetic flux densities of the permanent magnets. In this respect, the design alternatives are important from the point of enhancing the torque density in the magnetic gear development. For the design considerations in this paper, the effect of the gear depth on the torque efficiency and the use of high temperature superconductors in the pole pieces are investigated. The finite element analysis performed in COMSOL indicated that the torque values established on the rotors of the magnetic gear increased with increasing the depth without changing the efficiency of the gear mechanism. It was also determined that the use of superconductor in the pole pieces increased the torque transfer. High ripple on the amplitude of the torque values suggests the necessity of the experimental verification and more advance analysis.

Due to fast response and high energy density characteristics, Superconducting Magnetic Energy Storage (SMES) can work efficiently while stabilizing the power grid. The challenges like voltage fluctuations, load shifting and seasonal load demands can be accomplished through HTS magnet as this device has a great potential to supply power for a time span varies from few seconds to hours. Solenoidal configuration has been widely employed (over toroidal) in the development of SMES prototypes as it is simpler to manufacture and allows an easier handling of the mechanical stresses imposed on the structure due to Lorentz forces. A micro-SMES of capacity 10 MJ can be employed to mitigate the challenges like load leveling, dynamic stability, transient stability, voltage stability, frequency regulation, transmission capability enhancement, power quality improvement, automatic generation control, uninterruptible power supplies, etc. In this work, solenoidal configuration has been engaged in the development of 10 MJ SMES Magnet using 2 G (SuperPower, YBCO having Tc = 90 K @0T) High Temperature Superconducting (HTS) tape. The superconducting tape has been cooled at 14 K using conduction cooling. The effect of maximum operating current (3250A, 2600A, 1950A and 1300A) on the inductance, maximum storable energy and length of superconductor has also been evaluated for a constant deliverable energy of 10 MJ. A numerical analysis is done on 10 MJ HTS SMES where perpendicular field of 3T has been considered. The effect of aspect ratio (solenoidal height to bore diameter ratio) on the normal component of the magnetic field has also been assessed. Lorentz forces (N/m3) have been evaluated in the superconducting domain. It has been concluded that it would be beneficial to operate at higher currents (i.e. more current through single tape) as it can reduce the total length of the superconductor. The perpendicular component of magnetic flux for the analysis is found to 2.96T which is less than 3T.

This study proposed two new micromechanics models to predict the effective properties of multiferroics composites with spring-type imperfect interfaces. The first model is a full field micromechanics scheme based on the mechanics of structure genome, a multiscale constitutive modeling framework, recently discovered to unify the micromechanics and the structural mechanics. The second model is a mean field micromechanics approach that extends the Mori-Tanaka scheme using the concept of the interior and exterior-point Eshelby tensors to multiferroics composites. The imperfect interface model assumes that the normal components of the fluxes (stress, electric displacement and magnetic flux) are continuous across the interface, whereas the potential fields (displacement, electric potential and magnetic potential) suffer interfacial jumps proportional to the normal components of the fluxes. In contrast to multiferroics composites with perfect contact conditions, the effective properties formulations show the dependence on the size of the reinforcements. Numerical examples of fibrous multiferroics composites are used to demonstrate the robustness and accuracy of the proposed micromechanics theories. The size-dependency of the overall properties shows the importance of imperfect interfaces in predicting the effective properties of multiferroics composites.

International audience; A geometric spatial reduction method is presented in this paper. It applies to port Hamiltonian models for open systems of balance equations. It is based on system projections which make use of the symmetries in the model and preserve the "natural" power pairing. Reductions from 3D to 2D and 1D domains are illustrated via two examples. The first one is a vibro-acoustic system with cylindrical symmetry where 3D-2D reduction is applied. The second one is the poloidal magnetic flux diffusion equation for tokamak reactors where the toroidal symmetry is used to perform a 3D-1D reduction.

Within the framework of a one-dimensional model, we calculate electronic spectra and persistent currents of imperfect (containing one or several defects) nanoscale Aharonov-Bohm rings made of Dirac materials like gapped graphene, silicene or germanene. The calculations show that at zero electric field, in ideal structures, such as the defect-free ring or the ring with a defect superlattice, the electron spectrum consists of touching each other magnetic bands or minibands, respectively, with intersecting energy levels at the band (or miniband) edges. Introduction of some irregularity in the system, e.g., a single defect or a defect sequence with arbitrary barrier heights, turns the crossings into anti-crossings at the center and the boundary of the magnetic flux Brillouin zone. In silicene (germanene) rings in axially-directed electric field, extra crossings arise at some internal points of the Brillouin zone due to breaking the spin-valley symmetry. Such crossings do not disappear even in the presence of irregularity. All crossings in the ring spectrum cause the discontinuities in the persistent current depending on the band filling. Replacement of crossings by anti-crossings due to the defect existence in the ring leads to replacement of the current jumps by a smooth dependence on the magnetic flux at low degree of filling. As the Fermi energy rises, the smooth function gradually turns into the discontinuous one completely coinciding with that of the defect-free ring, i.e., the current becomes independent of the presence of inhomogeneity in the ring in the limiting case of high filling.

Magnetoactive tissues are prepared from a mixture of silicone oil (SO) and various volume concentrations Φ of carbonyl iron (CI) microparticles impregnated in a cotton cloth. The obtained tissues are examined as dielectric materials for manufacturing electrical capacitors. By using the plane capacitor method, we show that the relative dielectric permittivity, apparent viscosity, modulus of elasticity, and the components of deformations and of mechanical tensions can be sensibly influenced by an external magnetic field and by Φ . These effects make the obtained tissues versatile candidates for applications which require textiles consisting of conductive fillers, powders, yarns etc. embedded into non-conductive fabric fibers and with pre-established strength and flexibility. An immediate application is in fabrication of magnetic field sensors for detection of magnetic flux densities in the range 40 ÷ 180 mT.

Magnetorheological elastomers (MREs) are novel class of magneto-active materials comprised of micron-sized ferromagnetic particles impregnated into an elastomeric matrix, which exhibit variable stiffness and damping properties in a reversible manner under the application of an external magnetic field. Characterization of highly complex behavior of these active composites is a fundamental necessity to design adaptive devices based on the MREs. This study is mainly concerned with in-depth experimental characterizations of static and dynamic properties of different types of MREs using methods defined in related standards. For this purpose, six different types of MRE samples with varying contents of rubber matrix and ferromagnetic particles were fabricated. The static characteristics of the samples were experimentally evaluated in shear mode as a function of the magnetic flux density. The particular MRE sample with highest iron particles content (40% volume fraction) was chosen for subsequent dynamic characterizations under broad ranges shear strain amplitude (2.5–20%), excitation frequency (0.1–50 Hz) and applied magnetic flux densities (0–450 mT). The results revealed nearly 1672% increase in the MRE storage modulus under the application of a magnetic flux of 450 mT, which confirms the potential of the novel fabricated MRE for control of vibration and noise in various engineering applications.

In this paper, the effects of driving current and voice coil motor’s (VCM) structure parameters (e.g. magnetizer height, width of working air gap and damping hole angle) on the static electromagnetic characteristics are numerically investigated. The results show that the driving current has remarkable effects on the electromagnetic force before magnetic saturation; the oversize current applied to the coil would weaken the electromagnetic conversation because of the energy losses. Besides, the permanent magnets’ structure were researched, in order to achieve the stronger electromagnetic force, the magnetizer was embedded in the middle of two permanent magnets, and the static electromagnetic characteristics were investigated. Furthermore, damping holes have significant influence on magnetic flux, the tendency of magnetic saturation will be enhanced with the further increase of damping hole. Among other parameters studied, air gap is the most important parameter affecting electromagnetic force owing to the variation of magnetic induction intensity.

Some evidences have confirmed that field coupling is much effective to realize signal propagation between neurons, and the biological function of synapse connection has also been modulated when field coupling is activated. These theoretical prediction and confirmation are approached on neuron model with electromagnetic induction and magnetic flux coupling is used to describe the effect of field coupling. Neuron is treated as a smart signal processor and neuronal activities can be reproduced in electric circuit by setting appropriate parameters. When time-varying current flows along the inductorium, magnetic flux across the coil is changed and induced electromotive force of the inductor is triggered. Indeed, exchange of magnetic flux between inductoriums (induction coils) can trigger modulation on magnetic field. Therefore, two nonlinear circuits can be connected to reach possible consensus of outputs by using this kind of field coupling. In this paper, two identical Colpitts oscillators are coupled by transformer which is introduced from partial inductance equivalent circuit (PEEC), and the potential differences between circuit nodes are analysed to find synchronization approach under field coupling. An unit matrix is used to derive the Master Stability Functions of the coupled systems, and the synchronization manifold of the system describes the effect of the parasitic elements on dynamical behaviour. It is also found that both of the gain of the oscillators and the coupling coefficient of transformer are important bifurcation parameters for synchronization manifold of the system. Similar investigation is as well practiced on printed circuit board (PCB) and the synchronization approach is confirmed under field coupling. This kind of field coupling provides another effective way to synchronization modulation via continuous exchange of field energy in the coupling device.