This paper proposes the design and evaluation method to decrease torque ripple for Surface mounted Permanent Magnet Synchronous Motor (SPMSM). SPMSM type was adopted because it has the advantage of high efficiency and convenience of control for water pump. The design proceeds based on designing a motor with reduced torque ripple and magnet volume compared to motor in reference, and this paper uses Finite Element Analysis (FEA) method to evaluate different kinds of rotor. Then, proceed with a design that shows the optimal torque ripple by adjusting the offset and angle.
The management of thermoluminescent dosimeters (TLDs) is of paramount importance in diagnostic medical and nuclear medicine environments where X-ray radiation and magnetic fields are present. This study aimed to develop a check-in/check-out system based on a webcam and barcode scanner to prevent the loss of TLDs and enhance their management. TLD barcode scanning was performed using a webcam and barcode scanner with a Python-based PyQt5 graphical user interface. The main functions of the system include TLD registration, check-ins, and check-outs. The performance of the system was evaluated based on barcode recognition speed, barcode scan execution time, and recognition accuracy. Barcode recognition speed showed no significant difference during check-in (p = 0.169), in contrast to the significant difference found during check out (p = 0.007). However, scan execution time was significantly shorter for the barcode scanner-based system (check-in: 3.68 seconds vs. 20.93 seconds, check-out: 3.89 seconds vs. 18.53 seconds, p < 0.01). Additionally, the barcode scanner-based system achieved 100 % accuracy, whereas the webcam-based system had significantly lower accuracy (check-in, 32.12 %; check-out, 28.47 %; p < 0.01). Implementing a barcode scanner-based approach in the TLD checkin/check-out system provides a faster and more reliable solution for TLD management.
This study examined the effects of repetitive peripheral magnetic stimulation (rPMS) and exercises on pain, neck disability, and muscle fatigue in chronic neck pain patients. Eightteen subjects were randomly assigned to experimental and control groups. The experimental group received rPMS combined with exercise therapy, and the control group applied general physical therapy and exercise therapy. Both groups received treatment time of 20 minutes per day, five times a week, for a total of 4 weeks. The subjects were evaluated by a visual analog scale (VAS), neck disability index, and muscle fatigue. In the experimental group, a significant decrease was observed in both VAS and NDI after treatment (p<.05), and there was significant difference compared to the control group (p<.05). In both the experimental group and control groups, significant improvement was observed in the muscle fatigue after therapy (p<.05), and there was no significant difference in the muscle fatigue compared to the control group (p>.05). The results suggest that rPMS combined with exercise effectively reduces pain, improves functional ability, and alleviates neck muscle fatigue in patients with chronic neck pain.
Accurate prediction of core losses in soft magnetic materials under high-frequency and high-flux-density conditions remains a significant challenge. This paper addresses this challenge by introducing an improved core loss separation model (INF-Bertotti). The core innovation of this research lies in the development of an interval-based nonlinear fitting (INF) method. This method enables the dynamic prediction of variable coefficients within the Bertotti loss separation framework, effectively capturing the complex nonlinear behavior of loss components that conventional constant-coefficient models fail to characterize. Comparative evaluations demonstrate that the proposed INF-Bertotti model achieves superior prediction accuracy. Furthermore, the practical impact of the model is validated through its successful application in the design optimization of a high-frequency transformer (HFT), highlighting its potential as a reliable and versatile solution for core loss prediction in high-frequency power applications.
Magnetocrystalline anisotropy (MCA) is a preference of direction of magnetization, a fundamental characteristic of magnetic materials. In cubic crystals like bcc-Fe and fcc-Ni, MCA vanishes identically due to symmetry. However, the tetragonal distortion along the z-axis can induce a non-vanishing MCA by breaking the cubic symmetry. Using first-principles calculations, we analyze magnetocrystalline anisotropy energy (EMCA) with respect to c/a ratio, a degree of tetragonalization. For Ni, E EMCA is found to be--78 p peV/atom and +89 p peV/atom, while for Fe, it is +44 p peV/atom and--41 p peV/atom at c/a = 1.05 and 0.95, respectively. Based on the analysis of electronic structure, we reveal how band shifts associated with tetragonal distortion drive the MCA. Furthermore, magnetostriction coefficients (lambda 001) are evaluated, producing values of 23 ppm for Fe and--52 ppm for Ni, consistent with experimental observations.
To monitor peripheral vascular conditions, we developed a portable measurement device that utilizes a magnetoplethysmogram (MPG) sensor implemented using a permanent magnet and a Hall element together with a photoplethysmogram (PPG) sensor to acquire peripheral pulse waveforms. The user's hand length (L-H) divided by the temporal delay (Delta tau) between two peaks of pulse signals obtained from the two sensors is used to calculate the spatial pulse wave velocity (SPWV). Analysis of the MPG and PPG output waveforms demonstrated stable, clearly periodic signals. We confirmed a meaningful property of SPWV from the preliminary pilot study measured by using the SPWV1 and SPWV2 monitoring devices. The difference between SPWV1 and SPWV2 arises from the pulse period correction. Because Delta(tau ave2) = Delta(tau ave1) + T-period, the denominator in the SPWV2 calculation increases, resulting in characteristically smaller SPWV2 values. For participant #1, SPWV1 remained within a relatively narrow band of 2.8 m/s similar to 2.9 m/s, and SPWV2 within 27 cm/s similar to 28 cm/s over the 60 min measurement window, demonstrating stable behavior. For participant #2, SPWV1 showed greater variability, increasing to a maximum at approximately 40 min before decreasing, while SPWV2 remained within 24 cm/s similar to 26 cm/s. The SPWV measurement system based on MPG-PPG is expected to enable convenient, non-invasive monitoring of peripheral vascular health.
This study proposes a design approach that applies grain-oriented(GO) electrical steel sheet as a means to improve both the cost and efficiency of a yoke-less linear permanent magnet synchronous motor(LPMSM). Conventionally, LPMSM are designed and manufactured using non-grain-orient(NGO) electrical steel sheet, and thinner laminations are typically employed to enhance performance and efficiency. Although thin laminations offer favorable loss characteristics by reducing eddy-current losses, their high material cost increases the overall system price. In this study, we propose a design method that improves thrust and efficiency even when using thicker GO steel, which is generally less expensive than thin NGO steel. The potential cost advantages and performance benefits of the proposed are verified through electromagnetic design and finite element analysis(FEA).
A new method that combines cosine pole arc trimming and high-order harmonics is proposed to address torque ripple issues in Halbach-array permanent magnet synchronous machines during high-performance operations. Tunable harmonic-modification functions are introduced at the edges of magnetic-pole slots based on a synergistic optimization strategy combining "multi-objective global optimization and local geometric modification" to effectively suppress torque ripple without significantly reducing the average torque. By focusing on a 9-slot, 6-pole Halbach machine, CHC-3, CHC-5, and CHC-7 schemes are designed and analyzed, and a cosine pole-arc contour modification equation is derived to parametrically describe the magnet's surface profile. Among the selected schemes, CHC-3 demonstrates highly effective torque ripple suppression by approximately 20-25%, decreasing the average torque by only about 1%.
Nanoparticle samples CoxFe3-xO4 (x=0.2, 0.4, 0.6, 0.8, 1.0) are manufactured using high temperature thermal decomposition (HTTD) method. Each sample is confirmed to have a single structural phase with a group of Fd-3m spaces by Rietveld refinement of the XRD diffraction spectra. The lattice constant increases linearly from 8.3759 & Aring; for x=0.2, to 8.3965 & Aring; for x=1.0. Through the VSM experiment, magnetic properties are verified by measuring magnetization and coercive force up to 15 kOe at room temperature. For x=0.8 samples, the saturation magnetization and coercive force field are Ms=71.9 emu/g and Hc=40.5 Oe, respectively. The hyperthermia test results show that the self-heating temperature of the sample x=0.8 was 63.7 degrees C under an alternating magnetic field of 250 Oe at 112 kHz. Successful superparamagnetic nanoparticles with doping fabrication can achieve high magnetization but low coercivity, which is suitable for hyperthermia.
Two-dimensional (2D) van der Waals materials have attracted considerable interest for nanoscale spintronic devices such as spin valves, spin-filter magnetic tunnel junctions, and magnetic field sensors. Understanding the intrinsic magnetism in these systems is essential, particularly as measurements often require ultra-sensitive magnetometry near detection limits, where artefacts and magnetic contamination can significantly affect results. Consequently, the reliability of magnetometric detection of ferromagnetism in such materials has been questioned. Here, we systematically investigate magnetic contamination introduced when Teflon or K-tape is used during sample placement for measurements and handling propose to mitigate or eliminate these artifacts. We present the temperature-and magnetic field-dependent magnetization data of 1T-TiSe2 obtained following these procedures, which is diamagnetic in the temperature range of 5-300 K.
Spin-orbit torque (SOT) offers efficient magnetization control using spin currents generated by the spin Hall effect and/or the Rashba-Edelstein effect through charge-to-spin conversion. Quantitative evaluation of the SOT efficiency is crucial for understanding charge-to-spin conversion and optimizing energy-efficient spintronic devices. We evaluate the SOT efficiency in Ta/CoFeB bilayers with different magnetic anisotropies using harmonic Hall measurements, which allow the extraction of damping-like and field-like effective magnetic fields. From these measurements, the effective spin Hall angle, corresponding to the charge-to-spin conversion ratio, is determined to quantify the SOT efficiency. The effective spin Hall angles are found to be-0.052 +/- 0.002 and-0.052 +/- 0.004 for the up and down magnetization states of the perpendicularly magnetized sample, respectively, and-0.051 +/- 0.001 for the in-plane magnetized sample. These results demonstrate that the SOT efficiency remains nearly identical, irrespective of magnetic anisotropy, when the same spin-current source (a 4-nm-thick Ta layer) is employed.
This study aimed to design and fabricate a structurally optimized, multi-angle adjustable assistive device made of lightweight polycarbonate to improve posture reproducibility and image quality in pelvic and lower extremity X-ray examinations. To evaluate its educational and clinical efficiency, the device was applied in both radiologic science training and clinical imaging environments. With the application of the device, the practical performance skills of radiologic science students improved by 44%, while satisfaction and confidence increased by 25.4%. In clinical imaging, the device demonstrated a 1.5% improvement in alignment accuracy, a 40% reduction in the number of exposures, and enhanced pelvic alignment accuracy. These results indicate that the proposed assistive device contributes to standardized radiographic positioning and improved imaging efficiency. Furthermore, due to the non-magnetic nature of the polycarbonate material, the device shows potential applicability in MRI-compatible and magnetically sensitive clinical environments, supporting its broader clinical utility.
Surface-mounted permanent magnet (SPM) machines using Halbach magnet arrays offer enhanced magnetic performance but are prone to increased magnetic saturation due to their assembled magnetic effects. This study aims to develop a hybrid analytical model that accurately predicts the electromagnetic behavior of Halbach-based SPM machines while accounting for magnetic saturation. The proposed approach couples the sub-domain method with an equivalent magnetic network (EMN). The subdomain model computes the unsaturated air-gap field, and the EMN introduces equivalent surface currents at saturation-prone boundaries to represent the nonlinear permeability. The proposed model demonstrates excellent agreement with finite element method (FEM), with the average torque deviation below 5% while requiring only about 3% of the FEM computation time. Experimental measurements of a prototype further validate the accuracy of the analytical predictions. The hybrid model therefore provides a fast, accurate, and physically transparent tool for the analysis and design of Halbach-based SPM machines under magnetic saturation.
We have studied magnetic properties of cobalt-doped and undoped CaFe1-xCoxAsF (x=0.0, 0.1) by using XRD, EDX, SQUID, and Fe-57 Mossbauer spectroscopy through wide temperature range. Polycrystalline samples were synthesized by 2-step solid-state reaction method using high purity Ca, Fe, Co, As and CaF2 powders. The structural and the magnetic aspects of the observations have been examined by comparing results of the cobalt doped and the parent compounds together. The strategy of Mossbauer spectroscopic analysis has been set in terms of the structural and the spin density wave characteristics, according to which the temperature dependence of hyperfine parameters have been explained. Subsequently, various constituent phases in the materials have been separated out by comparing the results obtained from the SQUID with those from the Mossbauer spectroscopy. It has been found out that undoped CaFeAsF has two different kinds of phase transition happening around similar to 120 K, about 10 K apart from each other. On the other hand, M-T curve of cobalt-doped CaFe0.9Co0.1AsF showed that the spin density wave phase and the superconducting phase coexisted below similar to 120 K, and finally displayed the onset of the superconductivity at 22 K. Moreover, superconductive CaFe0.9Co0.1AsF at 22 K still showed paramagnetic doublet, indicating there was no abrupt changes in hyperfine parameters observed across either the spin density wave transition or the superconductive transition.
