We report the correlation between the magnetic properties and lattice parameter of Fe_xCo_100-x alloys as a function of constituent concentration. The saturation magnetization increases with Fe content and has a maximum value at approximately x = 70 at.%. However, collapse in relative saturation magnetization is observed at approximately 30 at.% to 70 at.% of Fe in Fe_xCo_100-x alloys. The collapse is due to the formation of Co-Co and Fe-Fe antibonding states instead of Fe-Co bonds. The lattice parameter also shrinks at approximately 30 at.% to 70 at.% of Fe. This shrinkage is due to an increase in the number of nearest neighbor antisite atoms, which then leads to a decrease in the long range order parameter.

The amine functionalized CoFe₂O₄ nanoparticles were prepared by thermal decomposition method at reflux temperatures 160 ℃ and 172 ℃. The obtained CoFe₂O₄ nanoparticles at 160 ℃ reflux temperature show aggregation free poly-dispersed nanoparticles in 4-15 nm range. In an elevated reflux temperature of 172 ℃, CoFe₂O₄ show aggregated poly-dispersed nanoparticles in the size range of 20-46 nm. The saturation magnetization value at 300 K exhibited 51 emu/g at reflux temperature of 160 ℃. However, the sample synthesized at an elevated temperature of 172 ℃ has shown a coercive field value of 560 Oe with saturation magnetization of 68 emu/g.

In this study, we fabricate an integrated microfluidic chip with a planar Hall effect (PHE) sensor for single magnetic bead detection. The PHE sensor was constructed with a junction size of 10 μm × 10 μm using a trilayer structure of Ta(3 nm)/NiFe(10 nm)/Cu(1.2 nm)/IrMn(10 nm)/Ta(3 nm). The sensitivity of the PHE sensor was 19.86 μV/Oe. A diameter of 8.18 μm magnetic beads was used, of which the saturation magnetization was ~2.1 emu/g. The magnetic susceptibility χ of these magnetic beads was calculated to be ~0.14. The diluted magnetic beads solution was introduced to the microfluidic channel attributing a single bead flow and simultaneously the PHE sensor voltage was measured to be 0.35 μV. The integrated microchip was able to detect a magnetic moment of 1.98 × 10⁻¹⁰ emu.

In this study, for 6-20 MeV electron beam energy occurring in a linear accelerator, the authors attempted to investigate the relation between the effective source-skin distance and the relation between the radiation field and the effective source-skin distance. The equipment used included a 6-20 MeV electron beam from a linear accelerator, and the distance was measured by a ionization chamber targeting the solid phantom. The measurement method for the effective source-skin distance according to the size of the radiation field changes the source-skin distance (100, 105, 110, 115 cm) for the electron beam energy (6, 9, 12, 16, 20 MeV). The effective source-skin distance was measured using the method proposed by Faiz Khan, measuring the dose according to each radiation field (6 × 6, 10 × 10, 15 × 15, 20 × 20 cm²) at the maximum dose depth (1.3, 2.05, 2.7, 2.45, 1.8 cm, respectively) of each energy. In addition, the effective source-skin distance when cut-out blocks (6 × 6, 10 × 10, 15 × 15 cm²) were used and the effective source-skin distance when they were not used, was measured and compared. The research results showed that the effective source-skin distance was increased according to the increase of the radiation field at the same amount of energy. In addition, the minimum distance was 60.4 cm when the 6 MeV electron beams were used with 6 × 6 cut-out blocks and the maximum distance was 87.2 cm when the 6 MeV electron beams were used with 20 × 20 cut-out blocks; thus, the largest difference between both of these was 26.8 cm. When comparing the before and after the using the 6 × 6 cut-out block, the difference between both was 8.2 cm in 6 MeV electron beam energy and was 2.1 cm in 20 MeV. Thus, the results showed that the difference was reduced according to an increase in the energy. In addition, in the comparative experiments performed by changing the size of the cut-out block at 6 MeV, the results showed that the source-skin distance was 8.2 cm when the size of the cut-out block was 6 × 6, 2.5 cm when the size of the cut-out block was 10 × 10, and 21.4 cm when the size of the cut-out block 15 × 15. In conclusion, it is recommended that the actual measurement is used for each energy and radiation field in the clinical dose measurement and for the measurement of the effective source-skin distance using cut-out blocks.

This study examined the relationships between protein expression and Poly ADP ribose polymerase in brain cell death in brains damaged by thrombotic stroke and treated with the Full Wave- Cockroft Walton (FWCW) method of Transcranial Magnetic Stimulation (TMS). The two-way switching element for TMS drove a halfbridge inverter of the current resonance of direct current voltage (+) and direct current voltage (−), and the experiment was conducted by stimulating the mice with thrombotic stroke through a range of pulses. Thrombotic stroke was caused of ligation of the common carotid artery of male SD mice, and blood reperfusion was conducted five minutes later. Protein expression was examined in immune reaction cells, which reacted to an antibody to Poly ADP ribose polymerase in the cerebrum cells, and western blotting. Observations of the PARP changes after thrombotic stroke showed that the number of Poly ADP ribose polymerase reactions were significantly lower (p < 0.05) in the group treated with TMS of the FWCW than the group with thrombotic stroke 24 hours after its onset. The application of FWCW-TMS helped prevent the necrosis of nerve cells and might prevent the brain damage that occurs as a result of thrombotic stroke, and improve the function recovery and disorder of brain cells.

The aim of the present study was to examine whether mirror therapy, in conjunction with repetitive transcranial magnetic stimulation (rTMS), can improve the upper extremity function of stroke patient. This study was conducted with 35 subjects, who were diagnosed as a hemiparesis by stroke. The Mirror plus rTMS group was of 12 members who undertook mirror therapy in conjunction with rTMS, the Mirror group was of 11 members who undertook mirror therapy, and the control group was of 12 members who undertook sham therapy. A motor cortex excitability was performed by motor evoked potential, and upper limb function was evaluated by Fugl-Meyer Assessment, and Box and Block Test. Significant difference was shown after the experiment, in comparison of the groups in terms of latency, and as the result of post hoc test, significant difference was shown between the Mirror plus rTMS group and control group, and between the Mirror group and control group, respectively. Significant difference was shown after the experiment in comparison of the groups in amplitude, and as the result of post hoc test, significant difference was shown between the Mirror plus rTMS group and Mirror group, and between the Mirror plus rTMS group and control group. Significant difference was shown after the experiment, in comparison of the groups in FMA and BBT, and as the result of post hoc test, significant difference was shown between the Mirror plus rTMS group and Mirror group, and between the Mirror group and control group. The study showed that mirror therapy in conjunction with rTMS is more effective to improve upper extremity function, than mirror therapy and sham therapy.

The purpose of this study was to investigate the effect of pulsed magnetic field (PMF) and low frequency low level laser (LFLLL) stimuli on acupoint LI4 (Hegu) using photoplethysmography (PPG). Our PMF system was designed to generate maximum intensity of 0.20 T at a transition time of 0.16 ms, with pulse intervals of 1 Hz. The diode laser with wavelength of 650 nm and power of 5 mW was also employed. It was observed the change of the pulsating blood volume through measuring PPG signals from both hands. These results imply that stimulating acupoint LI4 with PMF and LFLLL improves the circulation of peripheral vascular system. In particular, PMF stimulation brings a big improvement of the blood flow even with short term stimulation of 3-4 minutes compared to LFLLL stimulus.

The equivalent model of a permanent magnet (PM) plays an important role in electromagnetic system calculation. A type of subsection model for a PM bar is established, to improve the accuracy of the traditional equivalent circuit method. The mathematical expression, and its end verification condition, are presented. Based on the analytical method and finite element method, the leakage permeance calculation of a PM bar in an open magnetic circuit is investigated. As an example, for a given certain type of PM bar, the magnetic flux of each section is validated by experiment, and by simulation. This model offers a foundation for building a high accuracy equivalent magnetic PM model in an electromagnetic system.

Magnetic materials with large coercive force and high squareness ratio are currently developing to meet an industrial demand. Since a ferromagnetic material has hysteresis characteristics, it is hard to demagnetize a ferromagnetic material precisely. In this paper, we describe deperm processes and conduct an analysis of residual magnetization of ferromagnetic material using the Preisach modeling with a two-dimensional finite elements method (FEM). From the results, it was shown that an exponential decrement form of deperm protocol is more efficient than a linear decrement form because of the demagnetizing field in the ferromagnetic material.

The influence regarding the dehydrogenation speed, at the desorption-recombination state during the hydrogenation-disproportionation-desorption-recombination (HDDR) process, on the microstructure and magnetic properties of Nd-Fe-B magnetic powders has been studied. Strip cast Nd-Fe-B-based alloys were subjected to the HDDR process after the homogenization heat treatment. During the desorption-recombination stage, both the pumping speed and time of hydrogen were systematically changed in order to control the speed of the desorption-recombination reaction. The magnetic properties of HDDR powders were improved as the pumping speed of hydrogen at the desorption-recombination stage was decreased. The lower pumping speed resulted in a smaller grain size and higher DoA. The coercivity and the remanence of the 200-300 μm sized HDDR powder increased from 12.7 to 14.6 kOe and from 8.9 to 10.0 kG, respectively. In addition, the remanence was further increased to 11.8 kG by milling the powders down to about 25-90 μm, resulting in (BH)_max of 28.8 MGOe.

We have synthesized ferromagnetic τ-phase Mn₅₄Al₄₆/α-phase Fe₆₅Co₃₅ composite by annealing a mixture of paramagnetic ε-phase Mn₅₄Al₄₆ and ferromagnetic α-phase Fe₆₅Co₃₅ particles at 650 ℃. The volume fraction (f_h) of hard τ-phase Mn₅₄Al₄₆ of the composite was varied from 0 to 1. During the annealing, magnetic phase transformation occurred from paramagnetic ε-phase to ferromagnetic τ-phase Mn₅₄Al₄₆. The magnetization and coercivity of the composite monotonically decreased and increased, respectively, as the f_h increased. These results are in good agreement with our proposed composition dependent coercivity and modified magnetization equations.

Nano-sized nickel substituted cobalt ferrite powders, Ni_xCo_1-xFe₂O₄ (0.0 ≤ x ≤ 1.0), were fabricated by the sol-gel method, and their crystallographic and magnetic properties were studied. All the ferrite powders showed a single spinel structure, and behaved ferrimagnetically. When the nickel substitution was increased, the lattice constants and the sizes of particles of the ferrite powders decreased. The Mössbauer absorption spectra of Ni_xCo_1-xFe₂O₄ ferrite powders could be fitted with two six-line subspectra, which were assigned to a tetrahedral A-site and octahedral B-sites of a typical spinel crystal structure. The increase in values of the magnetic hyperfine fields indicated that the superexchange interaction was stronger, with the increased nickel concentration in Ni_xCo_1-xFe₂O₄. This could be explained using the cation distribution, which can be written as, (Co_0.28-0.28xFe_0.72+0.28x)[Ni_xCo_0.72-0.72xFe_1.28-0.28x]O₄. The two values of the saturation magnetization and the coercivity decreased, as the rate of nickel substitution was increased. These decreases could be explained using the cation distribution, the magnetic moment, and the magneto crystalline anisotropy constant of the substituted ions.

Ni_0.6Zn_0.4Fe₂O₄ prepared using solid state reaction and sol-gel methods were compared for their structural and magnetic properties. Due to the much higher annealing temperature used in solid state reaction, the crystalline size was much larger than that of the nanoparticles prepared by sol-gel. The saturation magnetization of sol-gel nanoparticles was higher, and the coercivity was about 2 times larger, compared to the solid state reaction sample. By analyzing the integration intensity of x-ray diffraction peaks (220) and (222), we proposed that the difference in the saturation magnetization might be due to the inversion of cation distribution caused by the different preparation techniques used.

Copper doped Zinc Oxide nanofilms were prepared using a simple and low cost wet chemical method. The microstructures, phase structure, Raman shift and optical absorption spectrum as well as magnetization were investigated for the nanofilms. Room temperature ferromagnetism has been observed for the nanofilms. Structural analyses indicated that the films possess wurtzite structure and there are no segregated clusters of impurity phase appreciating. The results show that the ferromagnetism in Copper doped Zinc Oxide nanofilms is driven either by a carrier or defect-mediated mechanism. The present work provides an evidence for the origin of ferromagnetism on Copper doped Zinc Oxide nanofilms.

This paper proposes an indirect fault detection method for an onboard degaussing coil system, installed to reduce the underwater magnetic field from the ferromagnetic hull. The method utilizes underwater field signals measured at specific magnetic treatment facilities instead of using time-consuming numerical field solutions in a three-dimensional space. An equivalent magnetic charge model combined with a material sensitivity formula is adopted to predict fault coil locations. The purpose of the proposed method is to yield reliable data on the location and type of a coil breakdown even without information on individual degaussing coils, such as dimension, location and number of turns. Under several fault conditions, the method is tested with a model ship equipped with 20 degaussing coils.

This paper proposes an efficient reliability-based optimization method for designing a superconducting magnetic energy system in presence of uncertainty. To evaluate the probability of failure of constraints, samplingbased reliability analysis method is employed, where Monte Carlo simulation is incorporated into dynamic Kriging models. Its main feature is to drastically reduce the numbers of iterative designs and computer simulations during the optimization process without sacrificing the accuracy of reliability analysis. Through comparison with existing methods, the validity of the proposed method is examined with the TEAM Workshop Problem 22.

This paper presents an analytical prediction and experimental verification of the electromagnetic performance of a parallel magnetized surface-mounted permanent magnet (SPM) motor having a fractional number of slots per pole combination. On the basis of a two-dimensional (2-D) polar coordinate system and a magnetic vector potential, analytical solutions for flux density produced by the permanent magnets (PMs) and stator windings are derived. Then, analytical solutions for back-electromotive force (emf) and electromagnetic torque are derived from these field solutions. The analytical results are thoroughly validated with 2-D nonlinear finite element (FE) analysis results. Finally, the experimental back-emf and electromagnetic torque measurements are presented to test the validity of the analysis.

Position estimation that uses only active phase voltage and current is presented, to perform high accuracy position sensorless control of a SRM drive. By extracting the amplitude of the first switching harmonic terms of phase voltage and current for a PWM period through Fast Fourier Transform (FFT), the flux-linkage and position are estimated without external hardware circuitry, such as a modulator and demodulator, which result in increased cost, as well as large position estimation error, produced when the motional back EMF is ignored near zero speed. A two-phase SRM drive system, consisting of an asymmetrical converter and a conventional closed-loop PI current controller, is utilized to validate the performance of the proposed position estimation scheme in comprehensive operating conditions. It is shown that the estimated values very closely track the actual values, in dynamic simulations and experiments.