The chirality of a magnetic domain wall was modified in ultrathin ferromagnetic Co/Pt multilayer films by varying the repeat number n. Direct observations of field-driven asymmetric wall motion revealed a change in sign of the Dzyaloshinskii-Moriya interaction coefficient from positive (n = 1, 2, and 3) to negative (n = 4), implying the domain wall chirality changes from a left- to right-handed Néel wall. These findings provide a way to control the domain wall chirality in multilayers simply by changing the repeat numbers.

We report the influence of annealing temperature (600 ℃-1000 ℃) on structure, crystallographic phase transition, morphology, vibrational, and magnetic properties of CuFe₂O₄ nanoparticles synthesized by a facile solgel auto combustion technique. The as-prepared and 600 ℃ air annealed samples show cubic spinel structure, secondary phases of α-Fe₂O₃, and CuO (minute reflections), resulting in inferior magnetic properties. Further, the 800 ℃ air annealed sample discloses a structural phase transition from cubic to tetragonal phase and minute α-Fe₂O₃ secondary phase. This sample exhibits the highest coercivity (H_C) 1221.4 Oe and squareness ratio (M_R/M_20kOe) = 0.56. On the other hand, the sample annealed at 1000 ℃ in air reveals superior magnetic properties (magnetization = 24.5 emu/g & H_C = 484.7 Oe) compared to all other samples. The revolution of magnetic properties with annealing temperature originates from the morphology, cubic to a tetragonal structural phase transition, c/a > 1, and cation site occupation induced by Jahn–Teller distortion.

These authors contributed equally to this work.

We modified synthesis i.e. coprecipitation and centrifuge-precipitation procedures as well as substituted bismuth cation for tuning the structural, magnetic, and photocatalytic properties. The product was annealed at 1000 ℃ for 5 h. The results of XRD analysis show the single phase of high-purity magnetic nanoparticles is obtained experimentally. The vibrating sample magnetometer results indicate that saturated magnetization decreased slightly in the centrifuge-precipitation procedure compared to coprecipitation. Finally, the photocatalytic properties also change with the modification procedure as well as substituted bismuth cation. The highest reduction of 78.1 % in methylene blue under ultraviolet radiation indicates that nanoparticles in cobalt ferrite-based nanoparticles materials have the potential to function as photocatalyst materials.

To decrease the negative influence of the poor working environment on lubricating performance, a new hydrodynamic bearing with magnetic fluid is developed, whose lubricating performance can be significantly improved by external magnetic field. The mathematical model of magnetic intensity generating by a solenoid, which is designed as external magnetic field, is deduced according to Biot-Savart Law and validated by measurement experiment. The direct relationship of load-carrying capacity of bearing and magnetic intensity of external magnetic field is built, through analyzing the effect of magnetic flux density on magnetic fluid viscosity. The results showed that solenoid is reasonable to apply as external magnetic field, and its theory works. Magnetic intensity of external magnetic field can enhance and monitor the bearing load-carrying capacity until magnetic fluid reaches magnetic saturation.

After twenty years study of the exchange spring effect, this effect has shown strong potential in application on the perpendicular record process. It satisfies all the necessary properties required by the perpendicular record process. The exchange coupled patterned media also provide a new way to further increase the data storage in the future. Although studies involve many aspects of the exchange spring effect are taken by experiments and theoretical simulations, a systematic study on a magnetic island perpendicular switching for patterned media is not present. We studied the in-plane and out-of-plane switching process with domain wall movement coupling with the finite boundary condition. Many details like magnetic domain wall, coercive field, remanent magnetization and hysteresis loops are discussed to enhance the magnetic device design. An in-plane vortex domain wall was reported in the simulation and the magnetic loops can be artificially designed.

Research has been conducted on techniques for adjusting magnetic resonance imaging (MRI) parameters to acquire images with better characteristics. In this study, we aim to confirm the optimal parameter values through quantitative evaluation and tendency analysis of T2 weighted images of the human brain acquired by adjusting the flip angle, number of excitations (NEX), and bandwidth (BW) using the user-friendly MRiLab simulation program. We also considered noise level and similarity evaluation parameters. According to the results, as NEX increases and BW decreases for a flip angle of 90°, the noise level and similarity evaluation improved, whereas they became less optimal beyond a 90° flip angle. Excessive parameter variation was found to cause additional noise and artifacts in such images, resulting in a deterioration of image clarity. Therefore, we confirmed that setting appropriate parameters is critical in magnetic resonance image acquisition.

The purpose of this study was to confirm the utility of the median modified Weiner filter (MMWF) noise reduction algorithm in T₂-weighted brain MR images. We acquired brain MR images using both real experiment and simulation, and performed comparative evaluation with conventional noise reduction algorithms through calculation of factors for the noise level and similarity. As a result, evaluation of the noise level and similarity showed the most improved in the image, which the MMWF noise reduction algorithm was applied. Moreover, additional experiment was conducted using real MR device and water phantom to more clearly prove the efficiency of the MMWF noise reduction algorithm. The noise level and intensity profile results derived from the real T₂-weighted MR image proved the effectiveness of the MMWF noise reduction algorithm. In conclusion, the proposed MMWF noise reduction algorithm demonstrated a very promising performance for improving the image quality in T₂-weighted MR image.

This paper presents magnet shape optimization of permanent magnet coupling (PMC) for a 50 hp chemical pump system considering the linear and non-linear design parameters. Firstly, the size and topology of PMC are considered for the initial model. PM eddy currents are analyzed to select the initial model. Secondly, an optimization process is performed to get the maximum pullout torque for a given PM volume. The optimization is based on a two step process; firstly, non-linear design parameters are considered for optimization using 2-D finite element method (FEM). The optimization is performed to maximize the pullout torque of the PMC and reducing the PM volume. Kriging method and genetic algorithm are utilized due to the non-linearity of the design parameters in the optimization process. Secondly, linear design parameters are adjusted and 3-D FEM is utilized to achieve the target and incorporate the end effects. Using two-step design process, the number of design parameters are reduced in the first step which simplify the optimization process and computational time is reduced using 2-D FEM. After that, the axial length of the PMC can be used as a linear design parameter to obtain the required pull-out torque. The optimized model is then simulated using 3-D FEM to incorporate the end effects and experimental results are then presented.

The magnetic properties of amorphous alloy Co₆₇Fe₃Cr₃B₁₂Si₁₅ samples, which were produced by the melt-spinning method and annealed at various temperatures, are analyzed. We found the best annealing temperature for Co₆₇Fe₃Cr₃B₁₂Si₁₅ was 350 ℃ for 1 hour at 30 mTorr. We also produced a flux-gate magnetometer with the annealed samples with the best magnetic properties. The flux-gate sensor shows a noise level of 2.4 at 1 Hz, and 0.1 nT_p-p in the frequency domain with 1 Hz bandwidth.

The goal of this research is to investigate the difference of the piezomagnetic response of X80 pipeline steel caused by low- and high-cycle fatigue. A series of fatigue tests were performed and the piezomagnetic signals were measured. The results show that although the shapes of the magnetic curves for low cycle fatigue and high cycle fatigue are different, the evolution of the curves can be both divided into three stages. The relationship between the experimental results and the theoretical models are discussed. The piezomagnetic response of X80 pipeline steel provides a potential possibility for evaluating the residual fatigue life of the submarine pipeline.

Aiming at the problem of short stroke of giant magnetostrictive actuator (GMA), a design scheme of coaxial integrated macro-micro composite actuator is proposed by combining the long-stroke characteristics of voice coil motor with the high-precision characteristics of giant magnetostrictive actuator. Based on its structure composition and working principle, the magnetic field model of macro-motion of macro-micro composite actuator is established based on the analysis method of circuit, and the change characteristics of the driving magnetic field are obtained. The finite element method is used to verify the magnetic circuit characteristics. The results show that the magnetic circuit variation characteristics of the proposed coaxial integrated macro-micro composite actuator are consistent with the theoretical calculation results, and are consistent with the expected working process of this actuator, which indicates that the established magnetic field model is correct, and that the proposed coaxial integrated design scheme of the macro-micro composite actuator is feasible.

Aiming at the problem that the high-voltage inspection robot is susceptible to wind load when inspecting the line, which leads to poor stability and low safety of the airframe, a balanced method of magnetic torque based on HVDC magnetic f ield is proposed: The dynamic balance is achieved through the ampere torque which is generated by the current-carrying coil in the HVDC magnetic field to offset the wind load moment. According to the actual working conditions of the inspection robot, a magnetic torque simulation model which was calculated and simulated was established. The results show that the model could produce a magnetic torque which met the requirements under the set parameters. Finally, an experiment was conducted on the magnetic torque device which showed that the torque generated by the device was sufficient to meet the requirements in non-extreme wind speed environments. In addition, the method used the magnetic torque to offset the wind load moment, which provided an effective idea for facing more complex load situations.

This paper proposes an array sensing methodology with differential magnetic field for electrode tip position in different smelting periods for high-power submerged arc furnace (SAF). According to the difference of magnetic field distribution between the electrode zone and the arc zone, the magnetic field radiation model of SAF is constructed, and the array detection system of differential magnetic field is designed and developed. The magnetic field distribution information of electrode zone and arc zone is collected on the electrode line of SAF. The test curve appears to be consistent with theoretical simulation result which indicates that the peak point of the magnetic field distribution curve on the electrode line is near the electrode tip of SAF. Compared with the single-point detection method of differential magnetic field, this method shows higher performance in accuracy and real-time, which should make an important contribution to the measurement of electrode tip position.

This study examined the effects of repetitive peripheral magnetic stimulation on pain, disability, and quality of life in chronic low back pain patients. Thirty subjects were randomly assigned to experimental and control groups, and rPMS was applied to the experimental group for 10 minutes per day, 5 times a week for a total of 4 weeks. The subject’s was evaluated by a VAS test, KODI test, and SF-36 test. In the experimental group, significant decrease was observed in the VAS test and the KODI test after treatment (p < .05), and there was significant difference in the VAS test and the KODI test compared to the control group (p < .05). The results of this study suggest that rPMS applied effects the pain and disability in low back pain patients.

Recently, magnetic nanoparticles and planar Hall resistance (PHR) devices used in biomolecule diagnosis and biological applications have attracted considerable attention as biosensors. The voltage properties of a planar Hall device with a Ta/NiFe/Ta/NiFe/Ta multilayer that was prepared in a cross-shaped pattern at a width of 0.5 mm using a shadow mask, were investigated. The sensitive planar Hall voltage (SPHV) obtained from the planar Hall voltage (PHV) curves of a Ta(5 nm)/NiFe(6 nm)/Ta(t = 2-8 nm)/NiFe(6 nm)/Ta(5 nm) multilayered sample was a few mV/Oe in the fine magnetic field region of the external magnetic field of ± 1.0 Oe. In particular, the thickness of Ta(t = 8 nm), the PHR ratio, magnetic sensitivity, and SPHV improved significantly by as much as 36.4 %, 28 %/Oe, and 1.6 mV/Oe, respectively. These results can be used in the development of a PHR biosensor with a high sensitivity for the detection of nanoparticle-antibody binding, even in a simple structure formed only out of a ferromagnetic NiFe layer.

This study was conducted to compare the effects of low frequency repetitive transcranial magnetic stimulation (LF-rTMS) and high frequency repetitive transcranial magnetic stimulation (HF-rTMS) on upper limb function in stroke patients with acute stage. A total of 40 subjects were randomly assigned 20 each to the LF(1Hz)-rTMS group and the HF(10Hz)-rTMS group, and all subjects received intervention for 20 minutes a day, 5 times a week, for 2 consecutive weeks. The subjects' upper limb function was evaluated using the Wolf Motor Function Test (WMFT), Fugl-Meyer Assessment (FMA), Box and Block Test (BBT), and Jebsen-Taylor Hand Function Test (JTHFT). As a result of this study, there were significant differences between before and after intervention in WMFT and FMA in the LF-rTMS group (p < 0.05). In the HF-rTMS group, there was a significant difference between before and after the intervention in FMA, and there was also a significant difference between before intervention and follow up test (p < 0.01). There were no significant differences between groups in all dependent variables (p > 0.05). These suggest that LF-rTMS and HF-rTMS applied to the primary motor cortex had a positive effect on upper limb function in stroke patients with acute stage, but there was no significant difference in the effect between the two.

Background: Recently, an utmost attention has been devoted by researchers on the prestaltic movement of viscous flows due to its novel importance in daily life problems, human body and many physical systems. In era of biological systemns and health sciences, the prestaltic mechanism attribute impotant applications blood circulation in vessels, blood pumping in heart, food in esophagus etc. Moreover, the applications of novel Galerkin finite element scheme for solution of nonlinear partial differential equations associated with peristaltic flow problems is another challenging task for mathematicians. Owing to such motivativations in mind, this computational presents the magnetohydrodynamic peristaltic flow of viscous fluid at high Reynolds number induced by an asymmetric wall channel. The novel impact of magnetic force are also utilized as a novelty. Method: The equations which exploit the flow problem are numerically tackled with help of Galerkin finite element scheme. Results: The results are computed and show great validation for physical parameters like wave constants, amplitude ratio and Reynolds number. The validation of obtained results are worked out with already claimed data and achieved an excellent accuracy. The mechanisms of transport process is addressed in view of involved physical parameters namely wave constant, Reynolds number and Hartmann number. The graphical observations are successfully revealed for all parameters.