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The article discusses the problem of determining electrical parameters of superconducting coils with bare windings. Procedures for measuring these parameters are described; in particular, inductance was measured by the voltage of a linear current input at a given rate. Although it is demonstrated to be impossible to determine inductance in a winding with a bare superconductor in the normal state, the inductance of a winding is comparable to that of an insulated wire in a superconducting state at currents below the critical value. The results of measuring the inductance, radial resistance, static current-voltage and magnetic characteristics of two tape coils with bare superconducting windings, one of which had a soldered connection, are presented. The insulated and bare superconducting winding parameters were compared and measurement conditions for the latter were formulated. The results of the study are applicable to the design and operation of superconducting devices with bare windings, such as coils, magnetic storage devices, stator windings of electric machines, etc. [ABSTRACT FROM AUTHOR]

Superconductors play a crucial role in the advancement of high-field electromagnets. Unfortunately, their performance can be compromised by thermomagnetic instabilities, wherein the interplay of rapid magnetic and slow heat diffusion can result in catastrophic flux jumps, eventually leading to irreversible damage. This issue has long plagued high-Jc Nb3Sn wires at the core of high-field magnets. In this study, we introduce a large-scale GPU-optimized algorithm aimed at tackling the complex intertwined effects of electromagnetism, heating, and strain acting concomitantly during the quenching process of superconducting coils. We validate our model by conducting comparisons with magnetization measurements obtained from short multifilamentary Nb3Sn wires and further experimental tests conducted on solenoid coils while subject to ramping transport currents. Furthermore, leveraging our developed numerical algorithm, we unveil the dynamic propagation mechanisms underlying thermomagnetic instabilities (including flux jumps and quenches) within the coils. Remarkably, our findings reveal that the velocity field of flux jumps and quenches within the coil is correlated with the cumulated Joule heating over a time interval rather than solely being dependent on instantaneous Joule heating power or maximum temperature. These insights have the potential to optimize the design of next-generation superconducting magnets, thereby directly influencing a wide array of technologically relevant and multidisciplinary applications. Flux jumps can lead to premature quenching and irreversible damage of superconducting magnets. Here, authors developed a GPU-optimized algorithm aimed at tackling the complex intertwined effects of electromagnetism, heating, and strain acting concomitantly on real superconducting coils. [ABSTRACT FROM AUTHOR]

The AC loss of a high-temperature superconducting (HTS) coil is directly related to a superconducting power device's efficiency and operation cost, so the HTS coil has always been the research hot spot superconducting technology. Under the condition of the same, total amount of superconducting tape used, three kinds of superconducting coil models, namely single-pancake coil with single tape winding, single-pancake coil with double tapes winding, and double-pancake coil with double tapes winding, are built by using the finite element simulation software. By changing the external magnetic field's frequency and intensity, the characteristics of tape stacking and cake coil are studied, and the superconducting coil structure with the lowest loss under different working conditions is explored. Through simulation analysis and comparison, it was found that the overall performnace of single-pancake coil with double tapes winding is the best. It provides a reference for the design of a superconducting coil structure under the quantitative superconducting tape condition. [ABSTRACT FROM AUTHOR]

This article presents the impact of MgB2 wire bending and diameter on transport critical current density and irreversible magnetic field of a resultant coil. Unreacted MgB2 wires 500 mm in length and 0.63 or 0.83 mm in diameter have been used in the fabrication of small diameter (14 mm) superconducting coils. The coils were subsequently annealed under isostatic pressure of 1 GPa for 15 min at 700 °C and 725 °C. Our results indicate that larger wire diameter, higher annealing temperature, and bending lead to slight reduction of critical current density and irreversible magnetic field in the coil. [ABSTRACT FROM AUTHOR]

Ferromagnetic hysteresis measurements can be used to determine both magnetic and mechanical state variables that correlate with each other. Therefore, hysteresis measurements are suitable for mechanical material characterization. The application of standardized hysteresis measurement methods is complex and can only be used to a limited extent in an industrial environment. In this work, a BH (ferromagnetic hysteresis) curve is to be reconstructed on 22NiMoCr3-7 samples that are in different mechanically deformed states (different histories). The reconstruction of the hysteresis is performed by an impedance analysis of the H-field generating coil. The applied method demonstrates that the ferromagnetic hysteresis can be reconstructed by means of an impedance analysis and is sensitive to different states of plastical deformation. [ABSTRACT FROM AUTHOR]

A 500 MHz high temperature superconducting (HTS) and low temperature superconducting (LTS) hybrid NMR magnets with conduction cooling has been designed in the paper, in which the HTS insert magnet is designed and fabricated with an intra-layer no-insulation (LNI) layer-wound coil structure. An equivalent circuit model considering layer-wound coil helical structure coupled with a stacked homogenization T-A model is used to study the screening current behaviors and magnetic field homogeneity of the HTS-LTS hybrid NMR magnet. It can be found that the maximum value of the time constant of the LNI layer-wound coil is only determined by the copper foil resistance, which ensures a smaller charging delay. The screening current induced by self field and some special background field, which does not change the original radial magnetic flux direction of the LNI HTS magnet, optimizes the magnetic field homogeneity. The screening current induced by the LTS compensation coils is the reason for the deterioration of magnetic field homogeneity. Then, we use the screening current property to readjust the parameters of the background magnets, which make the homogeneity of the NMR magnet optimized. [ABSTRACT FROM AUTHOR]

This paper proposes a main-auxiliary cooperative receiving coil (MA-coil) with a lower space occupation rate and a simple control based on the time-sharing working principle, which can effectively improve the anti-misalignment capability of a dynamic wireless charging (DWC) system. First, the structure and circuit topology of the MA-coil are designed. The two auxiliary coils (A-coil) are connected in reverse series and symmetrically placed on both sides of the main coil (M-coil). Second, the output performance of the MA-coil in the y-direction is calculated based on the time-sharing working principle. The A-coil works by itself and enhances the output power when side shift occurs. Third, the most suitable ratio of coil width wM and wA is determined. The anti-misalignment performance and the effective side shift range are compared through simulation between the MA-coil in this case and the square coil. Finally, an experimental prototype is built to verify the feasibility of the proposed structure, and experimental results obtained from the prototype are basically consistent with the theoretical analysis. The anti-misalignment capability of the MA-coil is more than 20% higher than that of the square coil. [ABSTRACT FROM AUTHOR]

We have designed a 30-T superconducting magnet for important experimental facilities in condensed matter physics research. The critical current of rare-earth barium copper oxide (REBCO) tapes directly or indirectly affects the electromagnetic margin, central magnetic field, hysteresis losses, field homogeneity, and screening current–induced stresses (SCIS) of the magnet. Given the poor critical current consistency of REBCO tapes at 4.2 K and their complex field-dependence, the arrangement of double-pancake (DP) coils is crucial in superconducting magnets. Based on measurements of over 100 REBCO tapes at 4.2 K and under an 8-T perpendicular field, we studied the arrangement of DP coils with different critical currents to assess their impact on the electromagnetic margin, central magnetic field, hysteresis losses, field homogeneity, and SCIS of the 30-T superconducting magnet. The results indicate that, depending on the magnet's requirements for different performance aspects, DP coils wound with higher critical currents should be positioned in locations with lower sensitivity to critical current. This approach serves to reduce the operating factor, screening current–induced field (SCIF), peak hoop SCIS, and losses, respectively. These findings provide valuable insights into the design of ultra-high-field REBCO superconducting magnets and arrangement of DP coils. [ABSTRACT FROM AUTHOR]

The Bulk Superconductivity Group at the University of Cambridge is currently investigating the use of high-temperature superconducting (HTS) materials in wire and bulk form in order to increase the electrical and magnetic loadings of an axial gap, trapped flux-type superconducting electric machine. As part of this research, accurate 2D axisymmetric and 3D finite element models of superconducting coils have been developed to investigate and simulate their electromagnetic behaviour. Some of the recent advances in analysing the performance of HTS coils are highlighted, including the simulation of in-field performance and increasing the computational speed and accuracy of 3D models. Experimental and simulation results on the DC characterisation of a test circular, epoxy-impregnated HTS coil are used to interpret the effects of degradation due to epoxy impregnation from the coil's ideal performance. With this numerical modelling framework, it is possible to simulate a variety of complex devices in both 2D and 3D over a broad range of electromagnetic situations with good accuracy. [ABSTRACT FROM AUTHOR]

Quench detection is vital for the safe operation of insulated high-temperature superconducting (HTS) magnets. However, due to slow quench propagation and susceptibility of terminal voltage to current interference, it is difficult to detect quench for an insulated HTS magnet. Co-wound tape (CWT) compensation method and the balance bridge (BB) compensation method show improvements to the voltage method. Both methods can eliminate the noise generated by induced voltage with fast response and high convenience. In this work, the CWT compensation method and BB compensation method are used to study the quench detection of an insulated HTS magnet under various operating conditions. CWT compensation and BB compensation methods, having a signal-to-noise ratio of 45 and 39 dB, respectively, outperform the conventional voltage detection method (− 13 dB). [ABSTRACT FROM AUTHOR]

This paper presents a multifunctional coil technique to enhance the transfer efficiency of an inductively-coupled wireless power transfer (WPT) system, regardless of the alignment condition and size ratio between the transmitter (Tx) and receiver (Rx) coils. The technique incorporates an auxiliary coil on the Tx side, where current is induced through coupling from the primary coil. Since the Tx coil consists of two coils, transmission to the Rx occurs through the coil with the higher coupling coefficient, determined by the misalignment state. Additionally, by controlling this current using a varactor placed on the auxiliary coil, an optimal magnetic flux is generated based on the alignment condition and/or the size of the Rx coil. In perfect alignment, the auxiliary coil focuses the flux from the Tx to the Rx coil, maximizing transfer efficiency. In misalignment scenarios, the current on the auxiliary coil is adjusted to shift the effective center of the Tx coil, achieving the strongest alignment of the magnetic flux traversing the Rx coil. This adjustment, which can be controlled adaptively based not only on the degree of misalignment but also on the size of the Rx coil, enables virtually null-free operation across varying misalignment conditions and for different Rx sizes. Furthermore, as this multifunctionality of the proposed system is achieved with a minimal number of additional components-just a single auxiliary coil and a single varactor-the impact on the overall quality factor (Q) of the system is minimized, contributing to the higher efficiency. In a size-symmetric system, where the Tx and Rx coils have the same size, the efficiency reaches 98.1% in perfect alignment and remains above 60% with up to 135% misalignment relative to the largest coil dimension. In a size-asymmetric system, with the Rx coil reduced to a quarter of the Tx coil, the efficiency is 96.1% in perfect alignment and remains above 60% up to 95% misalignment. Despite its enhanced practicality through a simple structure featuring only one auxiliary coil and an asymmetric configuration integrated solely on the Tx side, the proposed technique surpasses previous methods by delivering significantly superior performance. Moreover, it demonstrates unprecedented tolerance to both misalignment and smaller Rx coil sizes, which is frequently encountered in practical applications. [ABSTRACT FROM AUTHOR]

This study introduces a low-field NMR spectrometer (LF-NMR) featuring a multilayer Halbach magnet supported by a combined mechanical and electrical shimming system. This setup offers improved field homogeneity and sensitivity compared to spectrometers relying on typical Halbach and dipole magnets. The multilayer Halbach magnet was designed and assembled using three nested cylindrical magnets, with an additional inner Halbach layer that can be rotated for mechanical shimming. The coils and shim-kernel of the electrical shimming system were constructed and coated with layers of zirconia, thermal epoxy, and silver-paste resin to facilitate passive heat dissipation and ensure mechanical and thermal stability. Furthermore, the 7-channel shim coils were divided into two parts connected in parallel, resulting in a reduction of joule heating temperatures from 96.2 to 32.6 °C. Without the shimming system, the Halbach magnet exhibits a field inhomogeneity of approximately 140 ppm over the sample volume. The probehead was designed to incorporate a solenoidal mini coil, integrated into a single planar board. This design choice aimed to enhance sensitivity, minimize B 1 inhomogeneity, and reduce impedance discrepancies, transmission loss, and signal reflections. Consequently, the resulting linewidth of water within a 3 mm length and 2.4 mm inner diameter sample volume was 4.5 Hz. To demonstrate the effectiveness of spectral editing in LF-NMR applications at 29.934 MHz, we selectively excited hydroxyl and/or methyl protons in neat acetic acid using optimal control pulses calculated through the Krotov algorithm. [ABSTRACT FROM AUTHOR]

In this paper, numerical simulation of the second generation (2G) high-temperature superconducting coils has been developed in the module of magnetic field formulation with 2D-axisymmetric model. The brevity of expressions and the consistency between the 2D model and 2D-axisymmetric model of this approach make it easier than the method of partial differential equations (PDEs) and magnetic fields module to simulate the high-temperature superconductors. The accuracy of this technique was certified through the comparison with the results of infinite long tape solved by the analytical equation and PDE method. Then, the simulation about a high-temperature superconducting coil with 40 turns was conducted, in which the anisotropic characteristics of 2G tapes expressed with the fitting formulation of J(B, 휃) was considered. The distribution of current density and magnetic field at different time steps, and the voltage variation for each turn in the coil were studied. It could be seen that the electromagnetic quantities at the inner turns of a coil must be especially noticed. And finally, the AC loss of our model was calculated. [ABSTRACT FROM AUTHOR]

A Lagrangian formalism is developed, which allows finding the magnetic potential energy of interactions in a system of superconducting inductors (coils with constant magnetic flux) and permanent magnets (coils with direct current). The explicit form of potential energy for the magnetic system with constant magnetic fluxes and direct currents allows the stability analysis in such magnetic systems both at equilibrium and in motion. A number of applications are indicated, which will benefit from this approach such as modeling of cyber-physical or technical systems of magnetic levitation. [ABSTRACT FROM AUTHOR]

The heart of the present-day MRI scanners is a superconducting magnet that produces a highly homogeneous field at the centre. A multi-coil actively shielded superconducting magnet is designed, having dry winding i.e. free from any epoxy, for a whole-body 1.5 T MRI scanner. The magnet produces a homogeneity of ± 3.3 ppm in a 45-cm field of view. The multi-coil magnet would experience the stresses from the various sources during operation. The winding pre-tension; the thermal strains, due to cooling; and the Lorentz forces that contribute to the overall operational stress are considered to calculate various parameters of the dry wound magnet. The winding pretension has been determined after a thorough analysis of the hoop stress and the radial displacement of various components of the winding pack at various winding prestress ranging from 30 to 80 MPa. The role of the slip plane and the material (SS 304L and AA5083) of the bobbin in determining the operational stress in the dry magnet has been studied. The operational stresses have been analysed in minimizing the radial gaps between the coil and the bobbin. The role of the number of over-binding layers and their winding pretension has been studied for the multi-coil 1.5 T MRI magnet. [ABSTRACT FROM AUTHOR]

The geometric characteristics of a saccular aneurysm play a crucial role in its rupturing. This article thoroughly investigates the impact of the sac centerline on aneurysm rupture, with a focus on identifying significant factors related to rupture at different time intervals. The study employs comprehensive computational simulations of six models of the ICA with varying coiling porosities and blood HCTs, using CFD analysis to examine WSS, OSI, pressure, and velocity within the saccular aneurysm for different sac centerlines. The results indicate that higher blood HCT levels lead to increased WSS and pressure values on the aneurysm wall, while OSI and mean velocity decrease. The study also reveals that coiling techniques can significantly reduce the risk of rupture, as decreasing coil porosity (increasing coil permeability) increases OSI and pressure while decreasing WSS and blood velocity within the aneurysm sac. [ABSTRACT FROM AUTHOR]

The research work proposed for the X-band microstrip line-based magnetic resonance imaging (MRI) coils has been accomplished with coplanar waveguide feeding and ha highlighted the design parameters to be employed in the internet of medical things (IoMT) features. The proposed research has focused on the wireless body area networks (WBAN) phenomenon in simulated human organs. It has been employed to study the electro-magnetic (EM) parameters of the simulated human organ and the functioning of wearable MRI coils on the human body. Therefore, these coils have been configured in triangle-shaped hierarchical structures, and each layer has been printed on both sides of the conductive strips. These proposed coils utilize a Bakelite substrate with a 1.6-mm thickness and an equivalent dielectric strength of 1.2. It has 69.9 × 85.2 × 1.6 mm3 dimensions and was fabricated using microwave integrated circuits (MIC). These coils have been generated at 8 GHz and this spectrum has been justified with the microwave X band (8–12 GHz) using the standard measured results. Hence, these coils have demonstrated 45.81-dB signal attenuation with a 1-dB standing wave ratio (SWR). Therefore, this research has extended to the different kinds of virtual simulation scenarios in diagnosis applications. Additionally, the research delves into the electromagnetic characteristics, encompassing electric and magnetic fields, the specific absorption ratio (SAR), and temperature. These characteristics are thoroughly analyzed using MRI phantom models within virtual environments. As a result of this comprehensive analysis, the suitability and efficacy of these MRI coils have met rigorous standards. These coils are highly demanded by complicated systems functioning in these bands for IoMT and MRI diagnosis applications. [ABSTRACT FROM AUTHOR]

We present advancements in a finite element method for computing the physical properties of magnetic microcalorimeters (MMCs). Utilizing the COMSOL package, we conducted 3D simulations of a meander-shaped Nb coil with a realistic geometry. The resulting magnetic field distribution showed good agreement with a previous 2D simulation and revealed non-negligible differences at the side edge of the sensor material. Employing the simulation results, we calculated the MMC properties and compared them with previous measurements. Our calculated values closely align with the measured values for the sensor magnetization, the pulse heights from alpha detection, and the coil inductance. [ABSTRACT FROM AUTHOR]

Achieving three-dimensional (3D) omnidirectional wireless power transfer (OWPT) without any active control is challenging. This paper proposes a square polyhedron transmitter (SPTx) based on the reverse current of parallel coil, which can create a 3D omnidirectional magnetic field. To minimize the counteracting of the reverse magnetic field, each coil is equipped with magnetic shielding material. The coils of SPTx are connected in series and excited by a single power supply without any current amplitude or phase control circuits. The performance of SPTx system is validated with different receivers (Rx) by experiments. In the experiment with dual Rxs, the maximum transmission efficiency is 79.6% with an efficiency stability rate of 49%. In addition, the output power does not affect the efficiency, and more Rxs will increase transmission efficiency. [ABSTRACT FROM AUTHOR]

Solenoid is the most preferred geometry for MJ class–based HTS-based SMES; however, current carrying capacity is limited by the radial component of magnetic field. Optimization of dimensions is required for reducing the refrigeration cost, cost of 2 G HTS tape, structural support, and cryostat dimensions. A new optimized shape, which looks like a solenoid from the outside but has a different inner radius for each double pancake (DP) coil, is obtained using teaching learning-based optimization (TLBO) for minimum length and 1 MJ stored energy. The structural integrity and the operating current of SMES coil degrade due to high Lorentz force; therefore, stress is also included in optimization process as a constraint. COMSOL along with MATLAB is used for shape optimization. The operating current is increased by reducing the perpendicular component in these novel shapes thereby, reducing the total HTS tape length. These shapes are compared with the optimized perfect solenoid in terms of HTS tape length, stress, and inductance. [ABSTRACT FROM AUTHOR]

The new definition of a kilogram in the International System of Units is associated with fixing the value of the Planck constant. Practical implementation of the new definition of the kilogram is carried out by comparing the mechanical and electrical powers in a watt balance. One of the main components of the watt balance is a coil with a current, moving in a constant homogeneous magnetic field. The parameters of the coil movement affect the accuracy of the watt balance. The coil must move strictly vertically without additional movements, including rotational displacements around the watt balance. An iris spring is proposed, in order to ensure vertical movement of the watt balance coil as a motion guide. Iris springs are characterized by low longitudinal rigidity with considerable rigidity in the transverse directions. A model approach has been developed in which, because of its complex geometric shape, the actual iris spring is replaced by a model that retains the basic properties of the original iris spring. A model of the lobe of an iris spring was proposed and studied in the form of a rectangular plate, with the corresponding equations of thin plate theory. For specified deformations (height of bend) of the lobe of an iris spring, the forces acting on the lobe are calculated. In weighting mode, the spring is practically not deformed, and its action on the coil with a current is of the order of 10–6 N. The angles of rotation of the inner ring of the spring for a given set of heights are calculated. The approach for the construction of an iris spring that is under study can be applied in the development and creation of watt balances in the Russian Federation. [ABSTRACT FROM AUTHOR]

REBa2Cu3Ox (REBCO) tapes with high critical temperature, high critical current density, and preferably mechanical properties have been put into use in various industries. Nonetheless, its complex anisotropy and "error field" caused by the screening currents are still challenges for commercial applications. In this paper, the influence of with or without ferromagnetic substrate on the AC loss of superconducting composite tapes is first explored. It is discovered that the above and below superconducting tapes #1 and #3 have the screening effect on the middle superconducting tape #2. Then, the REBCO high-field coils were equated based on the anisotropic homogenization technique, and the distribution characteristics of the electromagnetic field, AC loss, and Lorentz force of the equivalent REBCO high-field coils are calculated. By investigating the performance characteristics of the central magnetic field, it is found that the screening current has an effect on the central magnetic field and critical current density of the coils. Moreover, the magnetic field induced by the screening current can reach a maximum of 0.8 T, which results in a 7.8% "error field" at the center of the REBCO high-field coils. Simultaneously, the screening current also reduces the critical current density at the top and bottom of the coils. Finally, the distribution law of current density and radial Lorentz force in different engineering turns in the fully charged state is investigated. The results prove that the Lorentz force generated by screening current is approximately 2.7 times greater than that of non-screening current (copper coils). [ABSTRACT FROM AUTHOR]

In order to solve the cross-coupling problem in the multirelay magnetic coupling wireless power transfer (MC-WPT) system, a set of magnetic cross-decoupling coil structure is designed in this paper. The coupling mechanism uses the mutual decoupling principle of bipolar coils and unipolar coils to realize the decoupling of non-adjacent coils, while the adjacent coils remain coupled. The frequency characteristics and output characteristics of the cross-decoupling dual-relay system based on the LCC-Multi-S topology are studied. It is found that the system can achieve open-loop constant voltage (CV) output, and the frequency of the optimal efficiency does not deviate from the resonance frequency point. At the same time, the proposed coil structure is compared with the traditional four-coil structure. The experimental results show that the proposed coil structure achieves cross-decoupling and better CV output, suppresses frequency drift and improves system stability. [ABSTRACT FROM AUTHOR]

The current densities flowing in high-temperature superconducting wires are mostly non-uniform during operations (caused by the screening current effect). This is a major challenge to high-field superconducting magnets based on (RE)Ba2Cu3O7-x (REBCO; RE, rare earth) tapes, as to cause (a) uncertainty of the field distribution and (b) concentrated uneven Lorentz force that damages the magnet. For no-insulation (NI) REBCO coils, the current distribution would be even complicated when external time-varying fields induce extra transport current circulating in NI coils. For this study, a numerical model is established, and the results are compared with hall sensor measurements for an NI coil sample. Different with conventional insulated coils, for NI coils, it was measured that the variation of axial fields (parallel to REBCO surface) could introduce remnant current densities persisting on REBCO tapes, which generate remnant fields. These remnant fields would cause the distortion of the spatial field distribution of a magnet, and were also measured to exhibit constant field decay with logarithmic time. These remnant fields pose extra concerns for NI coils for applications in NMR/MRI magnets in terms of threatening the spatial field homogeneity and temporal field stability of these magnets. Practical cases are simulated, i.e., NI coils are under time-varying fields generated by its adjacent NI coils or background magnets during quench/fault. The induced current (and the resulted Lorentz forces) concentrates on one-side edge of REBCO tapes that is adjacent to the quenched/fault coils; this observation helps understand and protect the mechanical damage observed in recent operations of NI REBCO magnets. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative Magnetic Switch (MFS) designed to control and alter magnetic flux within energy system components, offering an alternative to conventional power electronic devices. The MFS comprises a low-current control coil, a control core, and a high-density magnetic flux-carrying main core combined with a main coil energy system. In this novel magnetic configuration, when a low-power current excites the control coil, the magnetic flux in the main core (supplied by the main coil) decreases to nearly zero. Conversely, when the control coil disconnects from the power source, the magnetic flux within the main core attains its maximum value. This operation positions the MFS as a groundbreaking concept within magnetic-based energy systems, akin to transistors in power electronics. The main outcomes of the MFS concept are that it can vary the magnetic flux of the main core in the large range, and it is a fast magnetic switch with a simple and low power loss control circuit and an independent control coil from the main coil. Analytical studies thoroughly elucidate the performance and advantages of this proposed magnetic switch, substantiated by Finite Element Method simulations and experimental prototype outcomes. [ABSTRACT FROM AUTHOR]

The voltage source active power filter (VS-APF) is being significantly improved the dynamic performance in the power distribution networks (PDN). In this paper, the superconducting magnetic energy storage (SMES) is deployed with VS-APF to increase the range of the shunt compensation with reduced DC link voltage. The proposed SMES is characterized by the physical parameter, inductive coil, diodes and insulated gate bipolar transistors (IGBTs). The deep Q- learning (DQL) algorithm is suggested to operate SMES based VS-APF for the elimination of harmonics under different loading scenarios. Apart from this, the other benefits like improvement in power factor (PF), load balancing, potential regulation are attained. The simulation studies obtained from the proposed method demonstrates the correctness of the design and analysis compared to the VS-APF. To show the power quality (PQ) effectiveness, balanced and unbalanced loading are considered for the shunt compensation as per the guidelines imposed by IEEE-519-2017 and IEC-61000-1 grid code by using dSPACE-1104-based experimental study. [ABSTRACT FROM AUTHOR]

This study examines the use of nonlinear magnetic field coils for spatial encoding in magnetic resonance imaging. Existing theories on imaging with such coils share a complex reconstruction process that originates from a suboptimal signal interpretation in the spatial-frequency domain (k-space). In this study, a new solution to this problem is proposed, namely a two-step reconstruction process, in which in the first step, the image signal is converted into a frequency spectrum, and in the second step, the spectrum, which represents the distorted image, is geometrically and intensity corrected to obtain an undistorted image. This theory has been verified by numerical simulations and experimentally using a straight wire as a coil model for an extremely nonlinear magnetic field. The results of this study facilitate the use of simple encoding coil designs that can feature low inductance, allowing for much faster switching times and higher magnetic field gradients. [ABSTRACT FROM AUTHOR]

Optimization of magnetic coupling mechanism is an important way to improve the performance of a dynamic wireless power transfer system. Inspired by the common radial magnetic core for circular coils, a new radial magnetic core for rectangular coils is adopt. Through simulation and experimental results comparison, which has higher coupling coefficient with the same core area. Combined with the magnetic circuit analysis, the magnetic flux leakage and conduction regions are divided into magnetic fluxes with different shapes, which magnetic resistances are calculated respectively. Based on the simulation results, parameter distributions of fluxes under different conditions are obtained. Therefore, the expressions of the coupling coefficient k of the adopt magnetic cores and coils and the design parameters of coils and cores are obtained. Taking the maximum k and the minimum rate of change of coupling coefficient with 100 mm displacement as the optimization objectives, a multi-objective optimization solution is carried out by using NSGA-II algorithm. The coil optimization scheme is obtained and verified by experiments. k and Δk are 0.442 and 6.8% respectively, and the errors are less than 5%. In the optimization process, there is no simulation model constructed. The optimization modeling combined of magnetic field segmentation method and parameter fitting has lower complexity and calculation time of optimization. [ABSTRACT FROM AUTHOR]

Purpose: In order to enhance the output performance of magnetic levitating vibration energy harvesters over a wide frequency range, this paper investigates performance enhancement strategies for the tri-magnet levitating bistable electromagnetic energy harvesters (BEEHs). Methods: The bistable nonlinear mechanism is achieved by magnetic interaction between the cylindrical and ring magnets, enabling the harvester to resonate over a wide frequency range. However, the gravity-induced asymmetric bistable potential adversely affects the output voltage response. Therefore, the bistable configuration with balanced potential well depth is proposed to improve the output performance. Results: Simulation results based on the basins of attraction show that the probability of the oscillator eventually stopping at the left and right-side potential wells is approximately the same for different initial conditions. Furthermore, the output voltage response of asymmetric and balanced BEEHs is investigated under different excitation conditions. The results show that the balanced BEEH can achieve the high-energy orbit response over a wider frequency range for the same excitation level. Two coil series connections are provided, and their performance enhancement mechanisms are analyzed. Simulation and experimental results illustrate that the series connection of coils with the same wound direction (Series 1) is more favorable for the BEEH to achieve inter-well oscillation, which is suitable for vibration environments with small excitation levels. The series connection of coils with opposite wound directions (Series 2) improves the peak output voltage but generates large electromagnetic damping forces, making it more suitable for operating conditions with high excitation levels and large load resistance. Conclusion: Balancing the potential well depth can facilitate oscillator travel across the potential barrier, and choosing the appropriate series coil solutions can exploit the BEEH advantages fully. These performance enhancement strategies have been proven to be effective in this paper. [ABSTRACT FROM AUTHOR]

Over the past 15 years, there has been a noticeable uptick in incidents involving children ingesting multiple magnetic foreign bodies which can cause injuries and gastrointestinal complications including death. The current study aimed to identify the prevalence, clinical presentation, and management of single or multiple magnet ingestions. A retrospective multi-central cross-sectional study was conducted to include all pediatric patients < 18 years presented to the emergency department with ingestion of single or multiple magnets and admitted across hospitals in Qatar, UAE, KSA, Tunisia, and Turkey between January 2011 and December 2021. Demographics, symptoms, management, and outcomes were analyzed. There were 189 magnet ingestions, of which 88 (46.6%) were multiple magnet ingestions. Most patients (55.6%) were male, and the median age was 3.9 (IQR 2–7) years. An abdominal X-ray was obtained in all cases. 119 (62%) patients were conservatively treated, 53 (28%) required surgical intervention and 17 (8.9%) underwent gastroscopy. None of the patients with single magnet ingestions experienced morbidity or severe outcomes. Multiple magnet ingestions led to significant morbidity including hospitalizations, perforations (44.3%), severe intestinal necrosis (19.3%), peritonitis (13.6%), severe abdominal infection (10.2%), and septic shock (4.5%). The rate of surgical intervention (59.1% vs. 1.0%) and gastroscopy (15.9% vs. 3.0%) was significantly higher in the multiple ingestion group compared to the single magnet ingestion group. No deaths were identified. A high risk of serious complications, including the need for surgery to remove the magnets and substantial morbidity may result from swallowing more than one magnet. Magnet safety requirements, public education, and improved legislation are urgently required. [ABSTRACT FROM AUTHOR]

Purpose: Due to the difficulty of establishing an accurate analytical model of magnetic induction intensity in the case of multiple permanent magnet layouts, it is necessary to develop a mathematical model that can accurately describe the magnetic field distribution around multiple permanent magnets from the basic electromagnetic field theory. Optimization of permanent magnet arrangement and coil size parameters is a potential way to improve energy conversion efficiency. Method: This work presents a mathematical model of the axial flux density distribution in a multiple permanent magnet configuration based on classical Maxwell's electromagnetic field theory. Theoretical calculations of the magnetic flux and its rate of change were completed and validated using ANSYS Maxwell software. In addition, the permanent magnet arrangement and coil parameters design were optimized to obtain the maximum induced electromotive force (EMF). Finally, the energy conversion performance was experimentally measured for different combinations of magnet and coil configurations. Results: Theoretical studies have shown that the magnetic flux changes of three homopolar aligned magnets are more significant than that of their two-magnet counterparts. Simulation results show that there is an optimal value for the coil height which maximizes the output open circuit voltage when the number of Ampere-turns is kept constant. The results show that the theoretical and experimental induced voltages of the three heteropolar arrangements of permanent magnets are significantly higher than those of the same polarity arrangement. Conclusion: The efforts of this work are expected to provide a sound fundamental theoretical reference for optimizing the configuration of electromagnetically coupled structures and improving the efficiency of vibration energy conversion. [ABSTRACT FROM AUTHOR]

Stacked superconducting strips are widely used in electrical equipment to improve their electrical characteristics, but AC loss can seriously affect the performance of this equipment. Therefore, developing methods to reduce AC loss has long been a research hotspot in the field of superconductivity. This paper establishes a 2D densification model for stacking superconducting strips to accelerate simulation speed, and analyzes the current and magnetic field amplitude dependence characteristics of AC loss in stacked superconducting tapes based on the model. The results indicate that the amplitude of the external magnetic field has a significant impact on the total loss in the stacked strip, but a significant change in AC loss as a result of the increase in the amplitude of the transmission current is only possible when the external magnetic field intensity is less than 0.03 T. In addition, the variation in the total AC loss in the stacked superconducting tapes and the factors involved were analyzed by varying stacking conditions such as interval and number of layers. [ABSTRACT FROM AUTHOR]

The second-generation (2G) high-temperature superconducting (HTS) coated conductors (CC) are increasingly used in power systems recently, especially in large-capacity superconducting magnetic energy storage (SMES). HTSCC in superconducting energy storage coil is subjected to thermal stress which is caused by thermal contraction due to AC loss. The thermal stress will degrade the critical currents and may cause the displacement of the superconducting coil and insulating epoxy resin. In this work, the AC loss of the superconducting coil is firstly obtained by finite element method (FEM) software COMSOL with the method of iterative conductivity. Furthermore, the effect of AC loss on the superconducting coil is thus analyzed by solving the coupling problems which include magnetic field, mechanical behaviors, and heat transfer in solids. The result shows that the AC loss of the superconducting coil is concentrated in the middle of the coil and the maximum AC loss density is 5.96 × 105 W/m3; the maximum stress laid at the inner radius of the coil and the maximum stress is 0.01 MPa. [ABSTRACT FROM AUTHOR]

We present key design parameters of an innovative 10 MW low-speed direct-drive superconducting generator by high-temperature superconductor coated conductors for the rotor windings. In the simulations, the generator has an iron rotor with the superconducting coils operating at 20 K while the rotor core and the cooper stator are at room temperature. The calculations have been performed by Finite Element Software Comsol Multiphysics. Electromagnetic design parameters, magnetic flux distributions, phase current, voltage, and loss distributions of the superconducting generator are introduced. In addition, the AC losses that arise during the current increase in the superconducting rotor were calculated separately using both the H- and AV-formulation forms of Maxwell's equations employing the non-linear current–voltage relation of the superconductor. The current distribution and magnetic field distribution of the superconductor coils, volumetric loss density distribution, and comparison of the losses of each coil layer have been analyzed and discussed in detail. [ABSTRACT FROM AUTHOR]

The behavior of the interlayer magnetoresistance Rzz is analyzed in quasi-two-dimensional layered metals in a magnetic field tilted at Yamaji angles at which the minimum of the interlayer conductivity is observed. The cases of the Lorentzian line shape of Landau levels and of the shape corresponding to the self-consistent Born approximation are studied. At high fields, the behavior Rzz B3/2 is theoretically predicted, which agrees well with experimental data. [ABSTRACT FROM AUTHOR]

The concept of next-generation spherical tokamak is being considered: the Globus-3 project, which, in its characteristics, is compatible with the infrastructure existing at the Ioffe Institute, but differs from the currently operating Globus-M2 tokamak in the stronger toroidal magnetic field (1.5–3.0 T) and increased duration of plasma discharge. The parametric analysis data are presented that determined the preliminary selection of the facility parameters. Three options for the electromagnetic system were considered: with the warm copper coils, with the pre-cooled copper coils and with the coils made of high-temperature superconductors. For the first option, the concept for designing the electromagnetic system and vacuum vessel of the facility has been developed. The basic shot scenario with duration of up to 3 s at the field of 1.5 T and plasma current of 0.8 MA is presented. [ABSTRACT FROM AUTHOR]

Introduction: Diffusion weighting in optically detected magnetic resonance experiments involving diamond nitrogen-vacancy (NV) centers can provide valuable microstructural information. Bi-planar gradient coils employed for diffusion weighting afford excellent spatial access, essential for integrating the NV-NMR components. Nevertheless, owing to the polar tilt of roughly 55 ∘ of the diamond NV center, the primary magnetic field direction must be taken into account accordingly. Methods: To determine the most effective bi-planar gradient coil configurations, we conducted an investigation into the impact of various factors, including the square side length, surface separation, and surface orientation. This was accomplished by generating over 500 bi-planar surface configurations using automated methods. Results: We successfully generated and evaluated coil layouts in terms of sensitivity and field accuracy. Interestingly, inclined bi-planar orientations close to the NV–NMR setup's requirement, showed higher sensitivity for the transverse gradient channels than horizontal or vertical orientations. We fabricated a suitable solution as a three-channel bi-planar double-layered PCB system and experimentally validated the sensitivities at 28.7 m T / m / A and 26.8 m T / m / A for the transverse G x and G y gradients, and 26 m T / m / A for the G z gradient. Discussion: We found that the chosen relative bi-planar tilt of 35 ∘ represents a reasonable compromise in terms of overall performance and allows for easier coil implementation with a straight, horizontal alignment within the overall experimental setup. [ABSTRACT FROM AUTHOR]

We present a novel Active Magnetic Shield (AMS), designed and implemented for the n2EDM experiment at the Paul Scherrer Institute. The experiment will perform a high-sensitivity search for the electric dipole moment of the neutron. Magnetic-field stability and control is of key importance for n2EDM. A large, cubic, 5 m side length, magnetically shielded room (MSR) provides a passive, quasi-static shielding-factor of about 10 5 for its inner sensitive volume. The AMS consists of a system of eight complex, feedback-controlled compensation coils constructed on an irregular grid spanned on a volume of less than 1000 m 3 around the MSR. The AMS is designed to provide a stable and uniform magnetic-field environment around the MSR, while being reasonably compact. The system can compensate static and variable magnetic fields up to ± 50 μ T (homogeneous components) and ± 5 μ T/m (first-order gradients), suppressing them to a few μ T in the sub-Hertz frequency range. The presented design concept and implementation of the AMS fulfills the requirements of the n2EDM experiment and can be useful for other applications, where magnetically silent environments are important and spatial constraints inhibit simpler geometrical solutions. [ABSTRACT FROM AUTHOR]

The AC losses of high-temperature superconducting (HTS) coils have a large impact on the efficiency of superconducting power devices, so the research on AC losses of HTS coils has become a current hot topic. This paper mainly studied the effects of coil turns, inter-turn spacing, and coil radius of the same superconducting coil structure on its magnetization loss in the external alternating magnetic field environment. Using the finite element simulation software, the two-dimensional axisymmetric model of single-pancake coil with double-tape winding is built. Under the condition of external alternating magnetic field with the same frequency and amplitude, the three structural parameters of superconducting coil are changed, respectively, to calculate the magnetization loss under different conditions. The simulation results are also analyzed theoretically to clarify the main reasons for the change of magnetization loss of the superconducting coil caused by the three variables. The results show that the magnetization loss of the multi-turn superconducting coil is mainly focused on the hysteresis loss. Within a certain range, the more turns of superconducting coil, the smaller the magnetization loss, while the size of inter-turn spacing, and coil radius are positively correlated with the magnetization loss of HTS coils. The simulation results are consistent with the theoretical analysis, which provides ideas and references for the subsequent study of the magnetization loss of HTS coils. [ABSTRACT FROM AUTHOR]

This article discusses the influence of MgB2 wire diameter on critical parameters, dominant pinning mechanism, and n value. Studies were conducted on multifilament MgB2 wires of the 0.84 mm and 0.64 mm diameter. The wires were annealed under 1 GPa isostatic pressure, between 650 and 730 °C. Studies show that the best results (Jc, Birr, n value, and point pinning mechanism) for a 0.64-mm wire were obtained with annealing temperature of 650 °C. However, the best results for wires with a 0.84-mm diameter were obtained with annealing temperature of 730 °C. This research was conducted for exploring the use of MgB2 wires in multi-section superconducting coils, e.g., main coils generating magnetic fields and compensation coils—increasing the homogeneity of the magnetic field. Our research indicates that the main coil made with larger diameter wires should be heated at higher temperature (730 °C). In contrast, compensating coils with smaller diameter wires should be heated at a lower temperature (650 °C). [ABSTRACT FROM AUTHOR]

We report the evolution of the superconducting properties of a commercial coated conductor during deoxygenation and reoxygenation processes. By analyzing the changes on the critical temperature, Tc, and critical current density, Jc, at 4 and 77 K, we have identified the conditions that cause a complete deoxygenation of the coated conductor and, also, the reoxygenation conditions that allow a recovery of the superconducting properties. A complete suppression of superconductivity happens at ~ 500–550 °C under a pure argon flow. After a complete deoxygenation, we observed that a reoxygenation process at ~ 400–450 °C in pure oxygen flow allows, not only a full recovery, but even an improvement in Jc, both at 4 and 77 K. Such an increase of Jc is kept or even enhanced, especially at 77 K, in the presence of magnetic fields up to ~ 6 T. A microstructural analysis by transmission electron microscopy did not give evidence of major differences in the densities of Y2O3 nanoparticles and stacking faults between the pristine and reoxygenated samples, suggesting that these defects should not be the cause of the observed enhancement of Jc. Therefore, the combined action of other types of defects, which could appear as a consequence of our reoxygenation process, and of a new level of oxygen doping should be responsible of the Jc enhancement. The higher Jc that can be achieved by using our simple reoxygenation process opens new parameter space for CCs optimization, which means choosing a proper pO2-temperature–time trajectory for optimizing Jc. [ABSTRACT FROM AUTHOR]

The generation of a low-frequency low-pressure inductive discharge with ferromagnetic enhancement of the magnetic coupling between the coil and the plasma is investigated. The main features and advantages of this plasma generation method for surface processing technologies are considered. New experimental data on the electrophysical and dynamic characteristics of ferromagnetic-enhanced low-pressure inductive discharge in argon with the addition of oxygen are presented. It is shown that the radial distribution of plasma parameters in a gas-discharge chamber can be controlled using distributed discharge generation. Significant fluctuations in the electron temperature during the discharge electric field period are found, and the mechanism of their occurrence is analyzed. [ABSTRACT FROM AUTHOR]

A heat storage tank (HST), described in this paper, may be applied to numerous systems used for thermal energy generation and storage. Working principle and heat-flow processes of the HST remain the same and are independent of the systems in which the HST is being used. This paper presents a thermal-flow analysis of a heat storage tank (HST) operating in an air compressor heat pump (ACHP) and a dry cooler (DC) combined cycle. The HST is operated under transient conditions for four different ACHP steady states. The HST was analysed using lumped capacitance method. The heating power of a single coil varied from 2.2 to 3.2 kW. 50% increase in mass flow rate of heating water in the coils increased the HST water mean temperature by 5.6 °C. A differential equation for the HST water temperature variation was solved analytically and it was presented with the use of dimensionless numbers. The presented solution is of a general form. An important parameter such as number of the coils may be varied easily. Additionally, a Mathcad computational program was proposed for the estimation of HST-ACHP-DC system thermodynamic and thermal-flow parameters. System dynamics was studied using MATLAB/Simulink. An optimal operating parameters of the HST were found and are presented in the paper. The aforementioned parameters are as follows: mass flow rates of heating and cooling media in all three coils, mass flow rate of freshwater supplying the HST, number of loops in coils and resulting heat transfer area, diameter of the loops of the coils, diameter of the coils, time after which water in the HST reaches a steady value, time period within which the HST may fulfil demand for central heating and domestic hot water (DHW) preparation without being charged simultaneously. The presented analytical model was validated based on the available data in the field literature and a high compliance was reached. For this purpose theoretical model results were compared to results of HST computational fluid dynamics (CFD) simulations. The temperature calculated using the presented model differed from the one obtained by the CFD analysis by 2.96 K. [ABSTRACT FROM AUTHOR]

This report presents a design for a double-rod core fluxgate sensor. The design features two identical conventional fluxgate sensors with their excitation coils connected in an anti-parallel configuration while the pick-up coils are interconnected in the same orientation. The purpose of the sensor is to detect displacement in general machining machines. The sensor consists of an excitation coil and a pick-up coil wrapped around a core made of the high permeability amorphous alloy Metglas 2714A ribbon, which has low hysteresis and a highly saturated magnetic field. The cores are bar-shaped and precision-cut with double core layers to increase flux density. The sensor's high sensitivity of 206 mV/mT and low noise of 0.4 nT/sqrtHz@1 Hz were experimentally determined. In distance measurements, the device has a responsivity of 2.18 V/mm with an initial mounting position to the target of 3 mm. The results indicate that the proposed design is suitable for displacement applications. [ABSTRACT FROM AUTHOR]

Aiming at improving the cooling of motor annular water jacket, the effects of different water jacket designs and pump rotation speed and epoxy resin filling on the flow field characteristics and motor temperature distribution were studied. Results show that uneven flow distribution leads to high temperature of motor coil and large temperature gradient. The optimized water jacket has better flow, uniform flow distribution of long and short paths, higher utilization rate of coolant, and the coil temperature is 2 °C lower than that of original model. On the basis of optimized water jacket, when epoxy resin filling methodology and pump rotation speed increased to 5000 r/min are applied, the coil temperature can be reduced by 16 °C compared with the original model. From the cooling performance optimization results in current case, the improvement order from the smallest to the biggest is the optimization of motor water jacket flow field, optimization of motor water jacket system flow rate, and the epoxy resin filling. To meet the cooling demands of motor, the comprehensive effects from the aspects of reducing coolant system resistance, increasing pump speed, epoxy resin filling and other effective technologies are ought to be considered for all case studies. [ABSTRACT FROM AUTHOR]

Object: Exploring mouse brains by rapid 3D-Diffusion Tensor Imaging (3D-DTI) of high spatial resolution (HSR) is challenging in vivo. Here we use the super resolution reconstruction (SRR) postprocessing method to demonstrate its performance on Microtubule-Associated-Protein6 Knock-Out (MAP6-KO) mice. Materials and methods: Two spin-echo DTI were acquired (9.4T, CryoProbe RF-coil): (i)-multislice 2D-DTI, (echo-planar integrating reversed-gradient) acquired in vivo in the three orthogonal orientations (360 μm slice-thickness, 120 × 120 μm in-plane resolution, 56 min scan duration); used in SRR software to reconstruct SRR 3D-DTI with HSR in slice-plane (120 × 120 × 120 µm) and (ii)-microscopic 3D-DTI (µ-3D-DTI), (100 × 100 × 100 µm; 8 h 6 min) on fixed-brains ex vivo, that were removed after paramagnetic contrast-agent injection to accelerate scan acquisition using short repetition-times without NMR-signal sensitivity loss. Results: White-matter defects, quantified from both 3D-DTI fiber-tracking were found very similar. Indeed, as expected the fornix and cerebral-peduncle volume losses were − 39% and − 35% in vivo (SRR 3D-DTI) versus − 34% and − 32% ex vivo (µ-3D-DTI), respectively (p<0.001). This finding is robust since the µ-3D-DTI feasibility on MAP6-KO ex vivo was already validated by fluorescent-microscopy of cleared brains. Discussion: First performance of the SRR to generate rapid HSR 3D-DTI of mouse brains in vivo is demonstrated. The method is suitable in neurosciences for longitudinal studies to identify molecular and genetic abnormalities in mouse models that are of growing developments. [ABSTRACT FROM AUTHOR]

Due to the inherent nonlinear and sophisticated nature of superconducting wires/tapes, magnetic field computation of superconducting magnets by means of finite element methods (FEMs) is a time-consuming and complicated procedure. Although Legendre series method (LSM) was proposed as an alternative of FEMs, LSMs are not still fast enough. In current research, a surrogate model based on multi-layer artificial neural networks (ANNs) was introduced for the first time to dramatically reduce the computation time of a magnetic resonance imaging (MRI) magnet. To do this, firstly, the data related to the magnetic field were extracted based on LSM simulations for around 5000 different coil geometries. After that, the geometries of coils were used as inputs to a semi-deep learning ANN-based model in MATLAB software package. The minimum magnetic field in diameter spherical volume, maximum and minimum of total magnetic field were considered as outputs of the model, known as field indices. Then, ANN model was trained to calculate these field indices for any coil geometry. By doing so, magnetic field indices were estimated with a high accuracy based on the target values and also with extremely higher speed, comparing to FEM and LSM. Results showed that it takes 15 to 17 s for the proposed model to calculate the field indices for 750 different geometries whereas it takes for LSM-based model about 4 h. [ABSTRACT FROM AUTHOR]

How to improve the efficiency of IPT systems in the case of transceiver coil misalignment is a core problem that needs to be solved urgently. Compared with single-transmitter IPT systems, multi-transmitter ones exhibit greater power supply flexibility, which ensures stable operation despite misalignment. A topology of a multi-transmitter IPT system is proposed in this study. A grouping and switching control strategy of 3 × 3 multi-transmitter coils is designed on the basis of reconfigurable inverter. A method for charging area division is also put forward to improve the efficiency of the IPT system under the condition of power priority. Compared with the traditional multi-transmitter IPT system, the new multi-transmitter topology proposed in this study can realize the independent operation of each transmitter coil with the minimum number of passive devices. [ABSTRACT FROM AUTHOR]

We suggested an original method to investigate the Fermi surfaces (FSs) in the quasi-two-dimensional conductors some time ago [A.G. Lebed and N.N. Bagmet, Phys. Rev. B 55, R8654 (1997)]. It was based on a consideration of a perpendicular conductivity in quasi-two-dimensional metals in parallel magnetic fields in the framework of the Boltzmann kinetic equation, where it was shown that the conductivity was independent on impurities. In this paper, we demonstrate that the above mentioned result is much more general than the kinetic equation and can be obtained even in a fully quantum mechanical case. We suggest to investigate this possible phenomenon in the quasi-two-dimensional organic, high- , and some others superconductors in a metallic phase to judge if the Fermi liquid picture is valid for them or not. If the Fermi liquid picture is valid, then study of the perpendicular resistivity in the rotated parallel magnetic field allows to extract important information about the two-dimensional Fermi surfaces. [ABSTRACT FROM AUTHOR]