The traditional arc discharge process for producing metallic nanoparticles was modified to be applicable for the direct preparation of oxide nanoparticles by using both conductive and insulative precursors. The cobalt oxide nanoparticles were synthesized by feeding Co and Co₂O₃ into the air plasma. The as-prepared nanoparticles are spherical in shape with size in the range of 10 to 40 nm. The phases of CoO and Co₃O₄ were detected in the samples prepared from the precursors of Co and Co₂O₃, respectively. Weak ferromagnetism and an exchange bias up to 17.1 mT were observed in these antiferromagnetic nanoparticles, owing to the presence of a large fraction of the uncompensated surface spins and possibly the local disordered regions.

Effects of the uniform magnetic field on aqueous magneto-Nanofluid confined in a porous domain with wall stretching/shrinking non-linearly is analyzed via this communication. The problem is modeled using continuity, momentum and energy equation along with linear thermal radiation. The effects of physical quantities are observed for Cu, Al₂O₃, TiO₂ and Ag particles in water. The coupled boundary layer PDE’s are reduced into the system of ODEs by utilizing similarity transformation and solved using shooting and Runga-Kutta fourth order technique. Stability of the obtained results are also analyzed. The results are displayed through graphs. It is observed that the momentum boundary layer is thicker when silver particles are introduced in water. Whereas, temperature profile has the minimum value for silver nanoparticles and maximum for Titanium dioxide. Also, in case of shrinking sheet dual solutions are obtained along with smallest Eigen values.

In this paper, detailed magnetic force analysis of a 4-pole hybrid electromagnet system providing an advantage of full-redundant levitation is studied. The novel fragmented magnetic equivalent circuit method (MEC) is developed to accurately capture inherited nonlinear characteristics of 4-pole hybrid electromagnet to investigate force characteristics and magnetic field distribution. To confirm this method, two possible scenarios, which are levitation under plain core and levitation under dual-linear motor are composed. As well as, they are examined by both proposed method and FEM analyses. Comparative analyses of both methods revealed that force, inclination torque, and mutual interference can be easily captured with adequate accuracy while at the same time yielding less computation and set up time. Furthermore, the fragmented formulations of permeance functions can be generalized for the analysis and the design of similar devices which specifically involve inclination motions.

In this paper, a precise electromagnetic–thermal model of axial-flux permanent magnet (PM) eddy current couplers is proposed to calculate the eddy current loss and predict the copper plate node temperature. With subloop calculation method, the quasi 3-D electromagnetic field analytical model is established in cylindrical coordinate. Based on the electromagnetic field analytical model, magnetic field distribution, eddy current losses of PM, copper plate and copper back iron are analyzed under various loads. The eddy current loss of each loop in the copper plate is calculated, at the rated slip speed. Then, the thermal resistance network is carried out, in which the previously obtained eddy current losses are heat sources for calculating the copper plate node temperature. In the thermal study, the influence of various loads on copper plate node temperature rise is analyzed. Finally, the analytical predicted results are compared with the results of finite element method and measurement. The comparison results confirm the validity of the electromagnetic–thermal model.

In this paper, the characteristics of energy discharge in a flywheel energy storage system (FESS) are analyzed according to load condition mapped in the efficiency of a generator. As time goes by, the electromotive force (EMF) of a generator decreases in an FESS as a power source, but output power is maintained by boosting the generator voltage in a bidirectional power converter (BPC). Using the principle of operation of a boost converter, the variation of voltage gain in a BPC is investigated under the condition of load change, and current is compensated for the reduction of back EMF in a generator as its speed goes down. The loss of the FESS is separated into that of its generator, bearings, and BPC through experimental evaluation, and it has been verified that the generator plays a significant role in the efficiency of the FESS.

Linear oscillating machines are typically classified according to flux flow, as longitudinal and transverse flux type devices. In longitudinal flux linear oscillating machines, the direction of the current flow is perpendicular to the direction of the moving part, while the direction of the current flow in transverse flux linear oscillating machines is parallel to the direction of the moving part. Since the direction of the magnetic flux and the current are different in the two models, their electromagnetic characteristics can also be expected to be different. In this paper, we compare the electromagnetic characteristics of these two types of linear oscillating machines. For a fair evaluation of these characteristics, both models are designed to have the same stator outer diameter, permanent magnet volume, and no-load back electromotive force. In characterizing the devices, we analyze air gap flux density, flux linkage, and inductance, as well as the electromagnetic loss.

Aiming to obtain the influence mechanism of temperature on the torque transmission stability of magnetorheological fluid, firstly, a magnetorheological transmission device and its test-bed are established, and then, the thermal expansion, temperature pressure effect, heat volatilization, viscosity temperature characteristic, magnetic temperature characteristic and other related temperature characteristics were experimented systematically. The results indicate that the thermal expansion rate of 30 wt% magnetorheological fluid is 6 % and 18 % respectively at 120℃ and 220℃, and the working space pressure is 13 kPa when the temperature rises from 32℃ to 63℃. The thermal volatilization rate is still lower than 1 % at 200℃ for 8 hours. The viscosity of the silicone oil based magnetorheological fluid decreases by 78 % when the temperature increases from 20℃ to 240℃, and the saturation magnetization decreased by 6.2 %, 13 % and 23 % respectively at 150℃, 250℃ and 350℃. Furthermore, the temperature field distribution experiment shows that the highest temperature region is at the outer diameter of the disk and expands slowly along the radial direction. Moreover, compared with rotational speed, temperature is the main factor affecting the torque fluctuation of magnetorheological fluid.

Na-Ta ions co-doped M-type barium ferrites, BaFe_12-2x(NaTa)_xO₁₉, were synthesized at low temperature by the solid-state method. Na-Ta ion could occupy crystalline sites but not change the phase formation of barium ferrite. SEM images showed that samples had the regular and hexangular shape with 1-2 μm size. With the increase of Na-Ta, saturation magnetization (M_s) obviously decreased from 57.5 emu/g to 37.6 emu/g, and the coercivity (H_c) decreased from 4156 Oe to 2069 Oe. For dielectric properties, the real part permittivity (ε') increased when x from 0.0 to 0.3, reaching the maximum value in a range frequency of 10 MHz-500 MHz, while decreasing when x=0.4. This material would be applied in electronic devices using LTCC technology.

In the present study, the effect of Y addition on the glass forming ability and magnetic properties of [Fe_0.75B_0.20Si_0.05]_100-xY_x (x = 0, 1, 2, 3, 4) amorphous ribbons were investigated. The ribbons of 2 mm in width and 30 μm in thickness were obtained using the melt spinning technique. All ribbons were identified as fully amorphous by using X-ray diffraction. The thermal properties, including glass transition temperature, crystallization temperature, and supercooled liquid region, were measured by differential scanning calorimetry and thermomechanical analysis. The results showed that, with an increase of the Y content, the supercooled liquid region broadened, indicating an improvement of glass forming ability. The magnetic properties of the amorphous ribbons were measured by a vibrating sample magnetometer. In addition, it was confirmed that, with an increase of the Y content, coercivity tended to decrease.

Control rod drive mechanism is an electromechanical equipment that provides linear movement to a control rod assembly to control the reactivity of a nuclear reactor. The rod position indication system for the SMART control rod drive mechanism provides a position signal of a control rod assembly. It is an electric circuit consisting of reed switches and precision resistors installed at regular intervals. Because the reed switch manufacturer arranges the magnetic properties of the reed switch in Ampere-Turns and it is an uncomfortable dimension for an analytical estimation, it is not easy for the reed switch users to estimate the operability of a reed switch application at the design stage. Furthermore, this dimension is not standardized among the manufacturers. The performance of a reed switch application needs to be analytically verified to reduce the development risk. The operability of a reed switch application has been proved to be affected by the electromagnetic field generated around the application or an adjacent reed switch itself. Thus, it is necessary to have an effective means for a reed switch operability analysis at the design stage because the operating magnetic properties from the manufacture may not be applicable for a numerical analysis. In this paper, a new analysis methodology for a reed switch operability is proposed, and the feasibility is discussed for the rod position indication system.

The aim of double-blind, randomized and placebo-controlled study was to determine the therapeutic effect of pulsed electromagnetic fields (PEMF) therapy in treating chronic low back pain. The subjects were randomized into two groups: magnetotherapy group = 33 subjects, placebo group = 27 subjects. The group treated with magnetic field in solenoid received the therapy for 3 weeks – 5 times per week, total of 15 therapies. Magnetotherapy data: pulsed electromagnetic therapy, B_max = 0,681 mT, frequency 10 Hz, vector dB/dT = 0.976 mT/s, duration of therapy 20 minutes. In both groups the level of pain measured with VAS decreased and the function assessed with the Oswestry Disability Index improved immediately after the therapy and one month after the completed therapy, however the differences among groups were not statistically significant. Magnetotherapy with PEMF parameters and placebo therapy decreased the level of pain and improved the function in subjects but the differences between groups were not statistically significant.

The aim of this study is to review the diagnostic and monitoring performances of MRI and PET/CT in assessing diabetic foot complications, such as diabetic foot osteomyelitis (DFO) and Charcot neuro-osteoarthropathy (CN). Moreover, the goal is to identify the use of Near Infrared Radiation (NIR) as a clinical translation for screening and monitoring complications with no radiation exposure. Almost all the published materials included in this study were searched in the Scopus database and limited from the year 2000 to 2018 which resulted in 277 papers. Only 47 were utilized. In comparison, modalities have their own clinical strengths and limitations in terms of sensitivity and specificity, demonstration of anatomical details, confirmation of diagnosis and extent of infection, and radiation exposure. Also, NIR as an emerging tool could be a modality of choice in measuring blood glucose concentration within the body.

In this study, the length and area of t he artifact were quantitatively evaluated according to the direction of the magnetic susceptibility artifact. Using a self-made magnetic susceptibility artifact phantom the frequencyencoding direction in the 3.0T MRI system was changed in axial, coronal, and sagittal planes using T2 fast spin echo (FSE). The results showed a difference in length when the frequency encoding was changed from anteroposterior (AP) to right-to-left (RL) in the axial, RL to superior-inferior (SI) in coronal and AP to SI in sagittal planes (p < 0.05). In addition, the difference occurred when the magnetic susceptibility artifact area was measured according to the frequency-encoding direction conversion (p < 0.05). However, additional studies of magnetic susceptibility artifacts using various types of screws and plates are needed. This study provides basic data to prevent magnetic susceptibility artifact due to screw fixation.

This study presents hybrid control based on three-axis Helmholtz coil for manipulation of magnetic micro/nano robots. In general, magnetic force and torque control requires both Maxwell and Helmholtz coils. Therefore, the configuration of the magnetic manipulation system is complex and requires many power supplies. The hybrid method controls the three-axis Helmholtz coil and three power supplies through mechanical switch control to generate magnetic force and torque. Magnetic torque is controlled by the three-axis Helmholtz coil with a rotating magnetic field, and magnetic force is controlled by generating gradient magnetic field through the separated coils by the switch control. Three switches separate each Helmholtz coil and six switches control the separated six coil with the three power supplies. The hybrid control can provide simple configuration of coil system, various active locomotion, and precision control in complex environments. To verify the proposed method, we conducted magnetic simulation with various experimental tests.

Delivery Quality Assurance (DQA) is performed to evaluate the intensity modulated radiotherapy (IMRT). However, differences in the DQA results may be caused by factors such as the IMRT technique, treatment volume, etc. In this study, we compared five types of gamma index and four types of dose differences as IMRT technique, Treatment site, Volume of Planning Target Volume (PTV), Regularity Shape Index (RSI), indices of treatment planning evaluation. From January 1, 2016 to December 31, 2017, 32 patients who underwent IMRT plan were used to perform Step and Shoot (SNS) technique, Sliding Window (SW) technique, and Volumetric Modulated Arc radio-Therapy (VMAT) technique. After obtaining the Treatment Site, Volume of PTV, RSI, CI, HI, QOC according to each planning technique, nine factors of DQA were compared. As a result of the comparison, it was not possible to confirm the tendency of the items except the IMRT technique. The results of the IMRT technique showed the highest values for area gamma (< 1.0) and area dose difference (> 0.8) for SNS technique, and the lowest values for the other seven factors. For VMAT technique, the lowest value was obtained for area gamma (< 1.0) and area dose difference (> 0.8), and the highest value was obtained for the other seven factors. This study is limited to Electronic Portal Image Device(EPID). Therefore, it is necessary to study various equipment and program version in order to evaluate various DQA tools. In addition, there are limitations on the Treatment Site, Volume of PTV, and etc. necessary for evaluation. Therefore, it is considered that evaluation using various cases will be needed in the future. Nine factors, results of DQA, were a tendency by the IMRT techniques. The tolerance range of gamma index should be tightly in 80 % and 60 %, and the tolerance range of dose difference index should be tightly in 75 % and 25 %. Therefore, it can be concluded that accurate electromagnetic radiation therapy can be performed by applying the appropriate tolerance according to the IMRT technique in the future.

Fluoride application has an excellent effect for the prevention of dental caries, and 1.23 % acidulated phosphate fluoride (APF) gel is the most commonly used fluoride formulation for professional fluoride application. There has been a problem, however: its excessive intake may cause toxicity in the human body. The purpose of this study was to evaluate the amount of residual fluoride present in the saliva in the mouth over time by measuring it with ¹⁹F NMR spectroscopy after the topical application of 1.23 % APF gel. After 30-minute application, a very small amount of fluoride (0.000482 %) remained in the saliva in the mouth, indicating that there was no effect on the human body. Therefore, this study demonstrated that clinical fluoride application using 1.23 % APF gel is safe.

We designed a magnetic resonance (MR) compatible depth-encoding detector using cross point and dual-ended readout methods with wavelength-shifting (WLS) fibers. To evaluate the performance of the novel detector module, we used the DETECT2000 simulation tool to model the transport of optical photons in the crystal array. The detector is composed of two layers of crystal arrays, three layers of WLS fiber arrays, and two sensor arrays. The identification of crystal pixels was determined by the cross point readout method using a digital positioning algorithm, and the depth information in each crystal pixel was measured by the dual-ended readout method. The average pixel identification accuracy was 93.5 % (range: 84.4 %-100 %).

The purpose of this study is to investigate the stability of natural teeth whitening by analyzing the change on the tooth enamel surface and major mineral components, as well as tooth whitening using a natural material, such as fruit juice. Only the buccal surfaces of 20 premolar teeth extracted were assigned to 5 groups (n=4). For Group 1, normal saline was applied; for Group 2, strawberry and baking soda were mixed at a ratio of 3:1; for Group 3, lemon and baking soda were mixed at a ratio of 3:1; and for Group 4, baking soda and water were mixed at a ratio of 3:1. About 1 ml of each material was applied on the enamel surface using a toothbrush. For Group 5, 5 mm whitening toothpaste was applied using a toothbrush. Color changes using the CIELAB, pH measurement using a pH meter, surface morphology using scanning electron microscopy (SEM), and mineral content using electromagnetic wave (X-ray) photoelectron spectrometer (XPS) were measured. The whitening effect was highest in the teeth applied with lemon compared to the whitening toothpaste. The pH value was lowest with the lemon application, which showed a distinctly rough surface and porosity. The Ca and P values were lowest in the tooth surface whitened with lemon. It was confirmed that tooth whitening with natural fruit juice increased the roughness of the tooth surface due to the acidic low pH. It also caused enamel demineralization and posed harm to the teeth.

As the number of examinations in diagnostic radiology increases, direct or indirect medical radiation exposure for patients or workers has increased. To study the degree of medical radiation exposure, we measured and analyzed the lead apron’s shielding rate on direct radiation dose according to the quality of radiation beam. The distribution of space dispersal dose at X-ray exam was also measured at X-ray test on chest (100 kVp, 4 mAs, 100 mA) and L-spine AP (76 kVp, 200 mA, 32 mAs) to find out a better method to shield the worker’s radiation exposure. To measure the quality of X-ray in the scope of voltage generally used for X-ray exam in the hospital, half-value layer was estimated at the voltages which is ranged from 40 to 120 kVp. Effective energy was estimated at the same voltage range and the result was 12.5 keV~39.9 keV. The result of measuring radiation dose at increasing the voltage by 10 kVp each time on the range of 40~120 kVp, showed that the shielding rate of 0.50 mm Pb lead apron is superior to that of 0.25 mm Pb lead apron for all ranges of voltage. The difference of shielding rate between 0.50 mm Pb and 0.25 mm Pb lead apron increased as the voltage increased. The maximum difference was 10.2 % at 120 kVp. In conclusion, the lead apron will be able to shield the worker’s radiation

The purpose of this study was to investigate the effects of hand intrinsic muscles facilitation and functional task training with 1 Hz repetitive transcranial magnetic stimulation (rTMS) on cerebral motor cortex activity in stroke patients and to investigate the effectiveness of stroke rehabilitation. In this study, 20 adult stroke patients were randomly selected and divided into two groups of 10 each other. In the experimental group, hand intrinsic muscles facilitation and functional task training were performed after 1 Hz low frequency for 20 minutes and simple upper limb task training was performed in the control group. To investigate the changes of cerebral motor cortex activity after intervention, we measured Motor evoked potential (MEP) amplitude and latency. In both groups, MEP amplitude increased and MEP latency decreased after intervention. There was a significant difference between the two groups in MEP amplitude and latency (p < 0.01) (p < 0.05). Therefore, hand intrinsic muscles facilitation and functional task training with 1 Hz low frequency (rTMS) of stroke patients showed positive results in MEP amplitude and latency change of the injured cerebral cortex after stroke.

The correlation between the readout segment and the GeneRalized Auto Calibrating Partial Parallel Acquisition (GRAPPA) acceleration factor in the Read out segmentation of long variable echo-trains Diffusion Weighted Image (RESOLVE DWI) after enhancement was analyzed to investigate the effects of the signal intensity and the image distortion on the difference of the main field and contrast agent concentration. Twenty - four phantoms were prepared for each concentration of contrast agent, and signal intensity and image distortion were evaluated. At 1.5T and 3.0T, images were acquired using Readout segment, GRAPPA acceleration factor and echo spacing parameters, and Roundness (%) was measured using Regions Of Interest Contours. As the readout segment increased, signal strength and image distortion decreased. As the GRAPPA acceleration factor increased, signal strength increased and image distortion decreased. In RESOLVE DWI, it is helpful to minimize the distortions and artifacts caused by the signal intensity detection in the contrast agent phantom experiment and confirm the correlation between the readout segment and the GRAPPA acceleration factor depending on the main field, thereby making it possible to produce images with high diagnostic value.

The most common method for children’s oral health management is brushing the teeth, and for this, toothpaste is often used. Most of the toothpaste brands that are currently in the market, however, contain fluoride, which children should not swallow. This poses a problem for children as they have difficulty regulating their swallowing reflex and may thus end up swallowing the toothpaste with its fluoride content. Therefore, using ¹⁹F NMR spectroscopy, this study analyzed the amount of fluoride left in the oral cavity after brushing the teeth depending on the number of times that rinsing is done. It was shown that brushing the teeth using toothpaste containing 0.24 % NaF does not pose any risk and is safe even when rinsing just two-times.

A voltage-control spintronics memory (VoCSM) which has a potential of low energy consumption uses the spin-Hall effect (SHE) and the voltage-controlled magnetic anisotropy (VCMA) effect for its write operation. In this work, the relationship between the critical switching current (Ic_sw) and the SHE electrode thickness (t_N) is investigated in the range of 5 nm < t_N < 8 nm. In the fabrication process, we develop highly-selective patterning process to stop MTJ etching precisely on the surface of the SHE electrode. Using the technique, Ic_sw is reduced by half as t_N is varied from 8 nm to 5 nm, and Ic_sw of 112 mA at 20 ns write current pulse is obtained for MTJ size of 50 × 150 nm² on Ta(2 nm)/TaB (3 nm) electrode. The results indicate that the decrease in the SHE electrode thickness is a promised method to reduce Ic_sw, which leads VoCSM to a low-energy-consumption device.

A polycrystalline BaCoZnFe₁₆O₂₇ sample was prepared by the solid-state reaction method and wet ball-milling. The refined X-ray diffraction patterns revealed that the prepared sample was hexagonal with the space group P6₃/mm. To determine the spin transition temperature (T_S), the temperature dependence of the zero-field-cooled magnetization curves were measured under applied fields of 100 to 1000 Oe at various temperatures ranging from 4.2 to 295 K. T_S is the temperature at which the spin changes from the planar to the conical direction at the 135 K. From the hysteresis curves at various temperatures ranging from 4.2 to 295 K, the coercivity showed a change in slope at T_S. Mössbauer spectra were obtained at various temperatures ranging from 4.2 to 295 K, and the magnetic hyperfine field and electric quadrupole splitting of the sample showed abrupt changes around T_S.

In this paper, we study the fault detection algorithm and the fault compensation method in case of hall sensor fault of BLDC motor. In the case of a BLDC motor operating at high speed, the fault of the hall sensor is a very important factor that reduces the reliability of the control. If hall sensor fault occurs, ripple occurs in torque and current output value of BLDC motor. In addition, a phenomenon such as rapid braking of the motor may occur. Therefore, this paper assumes the fault of one or two hall sensors, and studies hall sensor fault detection algorithm and hall sensor fault compensation method. The peak-to-peak interval of the hall sensor signal is stored and the peak-to-peak interval is checked in real time to detect the fault immediately after the hall sensor fault. Unlike existing algorithms, it has higher reliability than existing fault detection algorithms, because it detects faults in real time. When a fault is detected, a signal of a normally operating hall sensor is input to the hall sensor fault compensation circuit. The output of the compensation circuit is a signal whose phase is delayed. The phase difference of each hall sensor signals is 120°. Therefore, the gain of the compensation circuit is appropriately selected to generate a signal for compensating for the fault of the hall sensor. Model and simulate motors, control circuits, and faulty hall sensors using MATLAB Simulink.

This paper presents three approaches to calculate the interacting magnetic force about spherical permanent magnet, respectively based on magnetic dipole-dipole model, equivalent magnetic charge model and equivalent magnetizing current model. We use all of three models to fully calculate and study the behaviors of lateral and axial forces with respect to the related positions between a pair of spherical magnets. The accuracies of the calculation results are compared with the experimental data. In conclusion, the magnetic dipole-dipole model has the most advantageous accuracy and efficiency for the magnetic force calculation about spherical permanent magnets on account of the particularity of sphere. Our study provides an important criterion for choosing a proper method to calculate magnetic force about spherical permanent magnet.

This paper presents an improved circuit model for predicting additional copper loss caused by circulating current effect. Based on basic circuit equations and winding topology, this model takes account of both slot and end leakage inductance which are separately extracted by 2-D and 3-D finite element method. Several simplified windings are wounded in a stator to validate the accuracy of the proposed model. The results shows that this model has high accuracy and the maximum error of loss factor is about 1.5 %. In addition, it is found that the circulating current loss factor will decrease as the end winding length grows up or winding temperature increases.

Electrical characteristics of a typical vehicle horn are determined by its resistance and inductance. The inductance is affected by factors such as the magnetic circuit, current magnitude, eddy currents and material properties. The mechanical characteristics of the vehicle horn are also affected by its material properties, the horn structure and its natural frequency. Mechanical and electrical parameters change during the operation of a vehicle horn. Therefore, it is difficult to predict the vehicle horn performance and hence, its design. In this study, firstly, the electrical and mechanical system of a vehicle horn are mathematically modeled. Secondly, the electrical and mechanical parameters are calculated using the finite element analysis method. Thirdly, to predict the operating characteristics of the vehicle horn, the electrical/mechanical system equations are solved by applying the parameters obtained from the finite element analysis. Finally, the simulation results and experimental results are compared and verified.

Magnetically controlled reactor (MCR) can compensate the capacitive reactive power generated by transmission line and enhance the stability of power supply, which is widely used in ultrahigh-voltage (UHV) power systems. In this paper, a novel structure for MCR with multi-taps is proposed. The MCR with multi-taps can switch its taps based on operation condition. The higher tap ratio is used to adjust the reactive power, and the lower tap ratio is fit for the stable grid. A switching algorithm is designed to make it work harmoniously and flexibly. For the adjustment of reactive power, this novel structure can perform better in regulated time without using higher tap ratios in practical operation, compared with the traditional structures.

Recently, studies on magnetic gears have been actively conducted. Magnetic gears can replace mechanical gears as they can perform noncontact power transfer, thereby minimizing loss and damage from friction. A magnetic gear has two rotors with different numbers of poles because of its structural characteristics. For a rotor with a relatively lower number of poles, large torque ripples occur owing to the increase in the permeance variation within the air gaps. Other electric equipment studies conducted thus far have primarily changed the shape of iron core to reduce torque ripples. However, since the magnetic gear has two air gaps, it is necessary to identify the relationship between the two gaps and the ripple before changing the shape of the iron core. In this paper, factors that affect torque ripple are classified and analyzed by examining the magnetic flux density of two air gaps, to propose an air gap structure that benefits the design of magnetic gears.

Demagnetization is crucial in national defense and is applied by deperming protocols. However, because a warship has an open structure, it is inevitable that demagnetizing fields are generated and magnetic fields that are different from the intended are applied. Therefore, in this paper, the effect of the demagnetizing field during the demagnetization process was analyzed. The magnetization distribution was simulated using a program combining the finite element method and Preisach model, and verified through experiments using specimens. In addition, experiments using scaled-down warship were performed. From the experimental results, we confirmed that Deperm-ME is superior to Anhysteretic, because the internal applied magnetic field was constantly applied.

Low-speed high-torque permanent magnet direct drive machine (LSPMDM) overcomes the shortcomings of traditional drive system, but its volume is large. In this paper, the numerical relationship between the motor external diameter and the rated speed is deduced, and improvement of the torque density is qualitatively analyzed for a dual-stator motor. Owing to that semi-inserted magnetic circuit structure and auxiliary slots under the poles can further increase the torque density of the motor, the effect of the shape, number and position of the auxiliary slots on the salient pole rate is also studied through comparative analysis. By incorporating the merits of dual-stator motor and semi-inserted magnetic circuit structure with the auxiliary slots, a novel motor topology is proposed, which is verified by finite element analysis with good performance.