In order to fabricate high-coercivity hard magnetic RE-Fe-B powders from the waste bulk magnets, the hydrogen decrepitation (HD) and hydrogenation-disproportionation-desorption-recombination (HDDR) processes were employed to the waste RE-Fe-B magnets. The optimum HD and HDDR conditions for the waste RE-Fe-B magnets were established through the systematic investigation on the effect of HD and HDDR treatment temperature on the magnetic and microstructural properties of final recycled powders. We found that the waste magnets were crushed into the flakes with a uniform size distribution when the HD treatment was carried at 200 ℃. By applying the HDDR process to the HD treated flakes at 920 ℃, high coercivity of 11.2 kOe could be achieved in the recycled RE-Fe-B HDDR powders. Based on the results from the microstructural characterization, the underlying reasons for the magnetic and microstructural changes of the recycled powders as a function of the HD and HDDR treatment temperature is discussed in detail.

This paper presents the new shape of a rotor bar improving the starting performances in a double-cage induction motor (IM). The rotor bar of a doble-cage IM is composed of a working bar, neck, and starting bar and each part has different effects on the characteristics of a motor. In this paper, it is confirmed that a starting bar has a dominant effect on the starting performances. The shape of a starting bar is designed by using the two ratios of the depth to width and the lower to upper width, respectively. The starting performances are closely analyzed by estimating the reactance and resistance of a rotor bar with respect to the depth through multi-layer method and FEA. Finally, by applying both the ratios to the starting bar, their mutual influence is scrutinized by using a response surface methodology and three models satisfying both starting torque and current aimed in this paper is proposed.

Aiming to solve the problem of magnetorheological transmission heat dissipation, a novel magnetorheological fluid transmission device is designed, and the torque of the device is analyzed. Based on electromagnetic theory, the magnetic circuit of the device is designed. The finite element method is used to simulate the magnetic field of the measurement device. Results show that the working magnetic induction can reach 0.5 T when the current is 1.6 A, which can meet design requirements. The magnetic induction intensity in the working space increases with the increase of the excitation current and permeability of the magnetic conductive material; decreases with the increase of the size of the working space; and increases with the increase of the size of the magnetic ring. The magnetic induction intensity in the working area is DT4C, 20 steel, and 45 steel from strong to weak. The experimental results are consistent with the simulation.

Numerical modeling by using the finite element method is developed for the prediction of magnetization. In this work, we modeled a superconducting strand made up of seven coupled filaments. We studied the influence of the deformation of the filaments on magnetization. We also studied the effect of the direction of the applied magnetic field on magnetization. We could calculate the magnetization of coupled superconducting filaments. We could also add the dependence of the current density according to the magnetic induction. We found that in the case where superconducting filaments are coupled, for a given spacing and whatever the direction of the applied magnetic field, the total magnetization of the strand does not depend on the deformation of the filaments in the strand if this strand is made up of several filaments.

A new winding structure for modular dual 3-phase permanent magnet machine, which makes it possible to reduce mutual coupling between two-winding sets of inverters and interference between phases that belong to the same inverter has been proposed in this study. The modular dual 3-phase system with overlapping winding technique has been widely employed in large-scale machine applications such as wind power production; however, its drawbacks include large torque ripple, long end-winding, and large magnetic mutual interference. To address these problems, a new modular dual 3-phase winding can be achieved by replacing adjacent redundant coils in one of the same phase coils with nonoverlapping winding. For clarity, three dual 3-phase machines are selected to examine their differences. The first is 32-poles/96-slots adopting a conventional overlapping modular winding ('Conv-1'), the second is 32-poles/36-slots based on the conventional nonoverlapping winding ('Conv-2'), and the other is 32-poles/36-slots adopting the proposed modular winding configuration ('Proposed'). The validity of the proposed structure is confirmed from simulation results obtained using finite element analysis.

Cerium-containing (Ce) rare earth magnets with extraordinary cost-effectiveness are widely investigated around the world. However, when the concentration of Ce is much more, the kind of these magnets exhibits very poor thermal stability and overall magnetic properties. To weaken these disadvantages, we take eutectic Y₅₀Ce₅₀ co-substitution alloys into account in this work. Magnetic properties, microstructures and metallurgical behaviors of (Y, Ce, Nd)-Fe-B magnets are systematically researched. For (Y₅₀Ce₅₀)₁₀Nd₂₀Fe_68.9B_1.1 SPSed permanent magnets, good overall magnetic properties are H_cj = 725 kA/m, J_r = 0.73 T and (BH)_max = 81 kJ/m³. It schematically depicts that coarse grain zones and fine grain zones occur during the spark plasma sintering (SPS) process. With the Nd content increasing, the deleterious CeFe₂ phases disappear. In addition, the volume fraction and width of coarse grain zones decrease. Ce-rich and Ce-lean regions are also observed in main phases, while Y and Nd elements are uniformly distributed. TEM results show that Nd and Ce are rich in the grain boundary and Y elements prefer to enter in 2:14:1 main phases. This work is favorable to a balanced utilization of high abundance rare earth elements in Nd-Fe-B magnets.

In order to better solve the problem of air leakage during compressor operation, based on the converging stepped magnetic fluid seal structure, the L₁₆ (4⁴) orthogonal test design and the numerical simulation of the finite element method are combined to optimize the sealing structure. Four factors, four levels and the corresponding orthogonal table are selected in this paper. The simulation results of each test are calculated and range values are studied. Finally, sealing pressure capability of the structure before and after optimization are calculated and compared. The results show that under the conditions of different axial and radial sealing gaps, the sealing pressure capability of converging stepped magnetic fluid seal structure has been significantly improved after orthogonal optimization, especially when the radial sealing gap is relatively small. The maximum pressure capability can be improved by about 11 %, which fully proves the effectiveness of orthogonal optimization. At the same time, the research results can also provide references for the application of other rotary sealing conditions.

The ability to improve the coercivity of sintered Nd-Fe-B diffused by Dy-Al-Cu alloy derived from electrolysis in a fluoride salt-oxide system was evaluated. The results show that with the increase in heat treatment time, the coercivity of the magnet firstly increased and then decreased. Holding at 900 ℃ for 4 h, tempering at low temperature for 3 h at 550 ℃, the coercivity of GBDPed magnet increased by 44.34 %, the remanence decreased by 1.26 %, the Dy-rich shell phase was recognizable, and the Nd-rich phase evenly distributed. Electron microscope analysis showed that when the GBDP time was longer than 4h, the diffusion of Dy from the shell phase to the matrix phase dominated, decreasing the coercivity with the increase in the diffusion time. The increase of Fe content in the grain boundary phase enhanced the exchange coupling between grains, which also reduced the coercivity of the GBDPed magnet. The infiltration of the matrix phase by excessive Dy and deterioration of (00L) texture of Nd-Fe-B resulted in the reduction of the remanence and the maximum energy product.

Failures in the industrial components are unavoidable due to material degradation from various sources, thus continuous monitoring and timely inspection is mandatory for structural safety. In the present study, the recently developed Transient Eddy Current Oscillations (TECO) method is used to detect wall-thinning in a stainless-steel plate. Unlike the conventional Eddy Current Testing impedance plane data a new interpretation method has been implemented to identify a thickness variation using the S-domain parameters. Furthermore, time and frequency spectral features are analysed to get more insight into the results. The decay time and the resonant frequency are the basis for the discussion to assess the wall thickness.

This paper examines the magneto hydrodynamic two-phase blood (Casson fluid) flow in a vessel with heat conduction between blood and particles. The temperature of both phases is also considered. The model for the flow under consideration is formulated in terms of partial differential equations. Then the classical model is generalized by utilizing the Caputo fractional order derivative. The generalized equations are then non-dimensionalized by using appropriate dimensionless variables. The exact dimensionless solutions are obtained via the joint application of Laplace & Hankel integral transforms. The influence of various embedded parameters on both the velocities (blood and magnetic particles) and the temperature distribution are presented graphically. It is worth noting that the particle and blood velocities decrease for increasing the values of magnetic parameter (H) which is useful to control the blood flow during magnetic therapy (for treating pain, such as the back, foot, or joint pain) and surgeries. It is worth noting that fractional model better describes the flow behavior than classical model by providing virous integral curves as shown in Fig.

To investigate the optimum flip angle that can enhance image quality, SNR (signal to noise ratio), and CNR (contrast to noise ratio), comparing the images obtained, applying flip angles, 11°, 14°, 17°, 20°, and 23° in getting Liver Hepatobiliary Phase image using 3D VANE XD(3D Multivane mDixon, Philips Healthcare) technique. Experiments were conducted on a total of 30 outpatients and inpatients to our hospital (HCC:10, Metastasis:10, Abscess:10). As for the equipment used in the experiments, Philips Ingenia 3.0T CX was used, and all parameters other than the flip angle were set the same to conduct the tests. As for the image analysis method, using the Image-J program (National Institutes of Health and LOCI), the SNR of the liver, kidney, and pancreas obtained from the images by flip angle before the contrast medium injection and the CNR between the lesion and the normal tissue after the contrast medium injection were measured to conduct comparative analysis. As a result of a comparison of images before and after the contrast medium injection by disease, when the flip angle of 17° was applied, SNR and CNR were measured higher than in the images of other flip angles (p<0.05). In the comparisons of the images taken before and after the injection of contrast medium by disease, when a flip angle of 17° was applied, the SNR before contrast medium injection was 28-29 % higher, and the SNR after the injection of contrast medium was 11 % up to 49 % higher than that at other flip angles. There was a difference in CNR before contrast medium injection of 30-43 % and CNR after contrast medium injection of 58-68 %. The measured value increased up to 17° and then decreased after that. Additionally, in the qualitative evaluation, Lesion Conspicuity (p=0.003), Image Artifact (p=0.0001), Lesion Delineation (p=0.0002), and Vascular Anatomy (p=0.0002) received the most excellent evaluations at 17°. In conclusion, in this study, the flip angle of 17° provided the highest SNR and CNR values when the tests were conducted using the free breath hold technique, 3D VANE XD Sequence. Thus, in liver MRI protocol tests, the overall diagnostic information was provided, including hypervascular tumor.

Among the representative types of magnetic resonance imaging (MRI) sequences, inversion recovery (IR) can improve the ability to detect brain lesions. The purpose of this study was to confirm the MRI characteristics according to TI changes in IR sequences. In this study, the MRiLab simulation program a newly developed, well-validated program was used to quantitatively analyze image characteristics with respect to the TI value in the IR sequence. Brain tissue phantom and standard phantom images were acquired by changing the TI at 100-ms intervals from 100 to 2,500 ms. In brain tissue phantom images, signal intensity (SI) values showed the lowest signals at TI values of 400, 700, and 2,500 ms in the white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF), respectively. The contrast evaluated in CSF-WM was superior at 400 ms and the lowest at 1,800 ms. In addition, the contrast evaluated in WM-GM was superior at 400 ms and the lowest at 1,500 ms. In the case of the brain standard phantom, the SI and contrast showed the same tendency as brain tissue phantom. In conclusion, an appropriate TI value was derived for obtaining images with excellent SI and contrast between brain tissues using a newly developed simulation program.

This study aimed to assess the effect of zero-filling interpolation (ZIP) and various spatial resolutions on quality assurance (QA). Two important variables for the assessments of magnetic resonance image quality were included with recommended acceptance criteria: high-contrast spatial resolution and low-contrast object detectability with reference limits. All acquired data were divided into two groups: group A (without ZIP) and group B (with ZIP). The spatial resolutions of both images of T1-weighted and T2-weighted imaging in both directions fulfilled the American College of Radiology (ACR) criterion in group B. The observed high-contrast spatial resolution values were significantly different between the two groups up to a matrix size of 320 × 320 (p < 0.05). On the other hand, with a matrix size ≥ 384 × 384, no significant differences between the two groups were observed in terms of high-contrast spatial resolution (p > 0.05). For low-contrast object detectability, the total number of measured spokes in all groups fulfilled the ACR criterion. However, the low-contrast object detectability values without ZIP tended to decrease as the matrix size decreased. The use of ZIP can improve high-contrast spatial resolution and low-contrast object detectability while reducing image blurriness.

Power generators, Hall accelerators, and flight MHD all require high levels of Hall current. The influence of Hall current and viscous dissipation on time-independent hydro-magnetic mixed convective radiative flow across a porous heated surface has thus been investigated using numerical computing and mathematical modeling in the current study. The fluid is electrically conducted and varies exponentially. It is assumed that the wall temperature and elongation rate will vary with specific exponential shapes. A solid uniform magnetic field B₀ is employed normally to the surface. The mathematical model of PDEs for incompressible flow is transformed into ODE by applying a numerical technique based on a finite-difference structure which includes a three-stage Lobatto IIIa scheme with the help of MATLAB. The obtained solution depends on the convergence constraints involving the radiation parameter R, magnetic parameter M, porosity parameter Ω, Hall parameter m, buoyancy parameter ε, temperature distribution parameter a, Eckert number E_c, Prandtl number P_r, and convective term bh. Graphs of the velocity and temperature profiles are explained via pertinent parameters. Skin friction factor, and Nusselt number are also evaluated and presented graphically and in tabular form. Results clarify that temperature profile reduces by increasing values of temperature distribution parameter whereas opposite behavior is noted for positive values of the buoyancy parameter.