In this research, a simple method has been presented to synthesize the magnetic - semiconductor Fe₃O₄/TiO₂ heterostructure nanocomposites via three steps: firstly, synthesis of Fe₃O₄ nanoparticles by co-precipitation method; thereafter, formation of Fe₃O₄/TiO₂ composites by sol-gel method; finally, annealing to form Fe₃O₄/TiO₂ anatase (denoted as Fe₃O₄/TiO₂-A) and Fe₃O₄/TiO₂ rutile (denoted as Fe₃O₄/TiO₂-R) heterostructure nanocomposites, respectively. The results of X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy show that the Fe₃O₄/TiO₂-A and Fe₃O₄/TiO₂-R heterostructure nanocomposite samples contain both magnetite (Fe₃O₄) and semiconductor TiO₂ (anatase or rutile phase, respectively). The as-prepared nanocomposite samples exhibit superparamagnetic properties at room temperature with high saturation magnetization (M_s) above 19.5 emu/g at the applied magnetic field of 11 kOe. Moreover, the Fe₃O₄/TiO₂-A and Fe₃O₄/TiO₂-R heterostructure nanocomposites with a low band gap energy of 2.89 eV and 2.81 eV, respectively, are promising to enhance the performance of photocatalytic activities in the visible light region for application in wastewater treatment.

Here nonlinear mixed convective entropy based nanofluid second order slip flow of magnetic and electric field is addressed. Both electric and magnetic field is considered for the problem formulation and the flow is generated by a stretched surface. Important slip factors, i.e., Brownian and thermophoresis diffusions are accounted. Total entropy rate subject to four types of irreversibilities (i) heat transfer (ii) chemical reaction (iii) fluid friction (iv) Joule or Ohmic heating is obtained through second law of thermodynamics. Thermal radiation, heat generation/absorption, dissipation, Brownian motion, Joule or Ohmic heating and thermophoresis effects are considered in the development of the energy equation. Activation energy to undergo the physical transportation or chemical transformation of atoms or molecules is further considered in the analysis of concentration. Firstly ordinary differential system is found, then numerically solved for flow field, entropy generation, concentration, temperature, skin friction, Nusselt number, Bejan number and Sherwood number through built-in-Shooting method.

Chain-like and diamond-shaped magnetic particle agglomeration (MPA) commonly forming in a weak magnetic field are simulated based on the finite element method (FEM), and the effects of particle diameter, magnetic field strength, particle relative magnetic permeability, and particle number in magnetic particle chains (MPCs) and diamond-shaped MPA on the strength of MPA are analysed in detail. The results show that magnetic forces on the centre contact points (CCPs) of MPA are positively correlated with the particle diameter, magnetic field strength, particle relative magnetic permeability, and particle number. In addition, the forces on the CCPs of the MPCs (N=2) have a square relationship with the particle diameter and magnetic field strength and have a power relationship of 1.25 with the particle relative magnetic permeability. The forces on each contact point decrease slowly from the centre to both ends in the MPCs and then rapidly decrease to one value (approximately 0.779 times the forces on the CCPs). As for the diamond-shaped MPA, with the increase in the angle α between the magnetic field and axis of diamond-shaped MPA, the force magnitude of the particle entrained parallelly in the diamond-shaped MPA shows a trend of a “cosine curve” shape and the minimum value is 2109 times that of the entrained particle’s gravity. The angle θ between the direction of the force and the negative X-axis shows a trend of a “sine curve” shape. When α = 25º and 155º, the angle θ of the force on the entrained particle reaches an extreme value, that is, θ = 21.87º. Only if the angle θ reaches 30º can the particle entrained parallelly escape from the diamond-shaped MPA. Thus, the diamond-shaped MPA remains in a stable state and it is difficult to disperse MPA by changing the direction of the magnetic field.

It is a well-known fact that the effects of magnetic fields on combustion can be used to control and optimize the flame deformation and the flame brightness. The kinetics and equilibrium properties of chemical reactions of combustion are influenced by the magnetic force exerted on paramagnetic species. In this study, the effects of non-uniform magnetic fields on one-stage methane combustion reaction are numerically investigated. It is known that NO, OH, and O₂ are paramagnetic species and the other species and methane have diamagnetic behavior. Considering these facts, the effects of non-uniform magnetic field on 10 main product species of methane combustion are studied, by minimization of the Gibbs free energy. The results indicate that variation of non-uniform magnetic fields from 0 to 0.08 Tesla leads to decrease in NO mole fraction by 99.6 % in temperature range 1500-2500 K. Furthermore, the combination of non-uniform magnetic field and raising the pressure have the beneficial result in decreasing NO and CO mole fractions as well as rise in temperature.

Hot-deformation behavior of Nd-Fe-B HDDR powder was investigated in order to understand the difference in texturing mechanism of HDDR and MQU-F powder during hot-deformation. The composition of the HDDR powder was the same as that of MQU-F powder. However, the grain size of HDDR powder (~300 nm) was eight times larger than that of MQU-F powder (~40 nm). After being subjected to hot-pressing at 700 ℃ under 200 MPa in a vacuum, the grains of the magnets made from HDDR powder and MQU-F powder have globular and platelet shapes, respectively. The remanence was 12.2 kG after die-upsetting process at the strain of 0.5. And it increased up to 13 kG at the strain of 1.4 although the grains still maintained globular-like shapes. The remanence of 13 kG was almost the same as that obtained the magnet from MQU-F powder at the same deformation condition. These results indicate that the hot-deformation behavior is quite different between HDDR and MQU-F powder.

We report the analysis of the crystal structure and the magnetic properties of Co_100-XMo_X alloys (0 < x < 100, Δx =10), obtained by mechanical alloying using a shaker mixer mill, at room temperature for 7 h. Crystal structure, morphology and magnetic properties of the Co-Mo system were characterized through XRD (X-ray diffraction), SEM (scanning electron microscopy) and VSM (vibrating sample magnetometry). The results showed different completely soluble solid solution, in almost all compositions. Williamson-Hall method revealed an increase in the crystallite size, decreased with the molybdenum content, from 27.34 nm to 8.02 nm for 0 to 100 wt.% of Mo, respectively. Saturation magnetization and the magnetocrystalline anisotropy, showed the same behavior, a diminution with the increase of the molybdenum content. However, the coercivity increased with the increment in Mo content, reaching a maximum of 63.79 kA/m for Co₂₀Mo₈₀.

Mischmetal-based permanent magnets of (MM,Nd)₁₂Fe₈₂B₆ were prepared by melt-spinning method via varying the relative content of mischmetal and Nd. The coercivity is low, and the squareness of hysteresis loop is poor in MM₁₂Fe₈₂B₆ ribbons. The x-ray diffraction pattern, maximum of δm value as well as the temperature dependence of magnetization indicates that the partial substitution of Nd for MM could improve the crystallinity in the mischmetal-based magnets, and both the coercivity and squareness of hysteresis loop increase with Nd substitution for mischmetal. The increase of squareness should be partially attributed to the improvement in the crystallinity of R₂Fe₁₄B crystal phase. For more than 4 at.% Nd substitution the coercivity is not less than that in corresponding (Ce,Nd)-based magnets, and the coercivity of 7.81 kOe and the maximum energy product of 15.41 MGOe were obtained in MM₈Nd₄Fe₈₂B₆ ribbons. These investigations show that it is reasonable to use the low cost mischmetal to prepare the resource-saving rare-earth magnets, and that optimizing the addition amount of Nd is necessary to improve the crystallinity and enhance the magnetic properties.

There are many seals designed for rolling bearings. One interesting perspective is the application of magnetic fluid seals for this purpose, because they are an alternative to commonly-used solutions and combine the advantages of contactless seals (e.g. labyrinths) and contact seals (e.g. rubber lip seals), therefore they have low resistance moment and high tightness. This publication describes rolling bearings and a magnetic fluid seal system in terms of the maximum sealing pressure, which was compared to the results of numerical simulations, and the influence of the magnetic field on the bearing torque was also investigated. The tests were carried out for various types of seal stage shapes. Different magnetic circuit configurations have been considered i.e. the main magnetic flux passing through the seals or rolling bearings (steel or ceramic). Studies have shown that a magnetic field increases the torque in the bearing and magnetic fluid seals may reduce the torque because part of the magnetic flux passes through the seal elements. This result is important because it shows that it's possible to reduce the negative effects of variable magnetic fields on rolling bearings by using additional elements of the magnetic circuit.

In this paper, the energy consumption of PMSM was compared simultaneously in direct and indirect drive systems, considering the efficiency of the operating point in the washing and dehydration modes. DD (Direct Drive) washing machines have the disadvantage of high-power consumption due to the difference in driving point efficiency of washing and dehydration. Therefore, in this paper, a method of changing the washing operation point using a gear is proposed. Two types of miniaturization models that satisfies the output level under two gear conditions are designed, and energy consumption with respect to the operating mode of the washing machine is analyzed and compared. From the viewpoint of power consumption, optimal stacking and gear combination model is selected. In conclusion, the energy consumption of the optimum gear model is decreased about 97 Wh and material cost of the motor down by 57.3 % compared with base DD motor.

Magnetic couplings are considered suitable for many industrial applications where a separation is required between the driver and the driven. Utilizing magnetic couplings allows the transmission of torque without any mechanical contact. Generally, permanent magnets (PMs) are utilized in magnetic couplings instead of electromagnets to avoid extra circuitry. Accurate design and analysis of magnetic coupling are essential to reduce the PM volume for the required output performance. 3D finite element method (FEM) is considered the most accurate as it takes into account the end effects, which arises due to a shorter stack length as compared to the diameter of the coupling. In this paper, a permanent magnet coupling (PMC) is designed and optimized to be installed in a chemical pump that is handling high-temperature fluid. A prototype was also manufactured and tested in the laboratory to verify the analysis.

A new type of 3-D micron-scale actuator is designed, which is mainly composed of four Galfenol rods, drive coils, base, magnetic yoke and output head. According to magnetostrictive model and structural dynamic model, the output characteristics of the actuator have been analyzed. The 3-D moving trail of the output head is controlled by the drive coils of the four rods. The actuator prototype is fabricated and experimental investigated. Good agreement is observed between the simulation and experimental results. The maximum output displacements of the X, Y and Z direction are 46 μm, 46 μm and 8.2 μm. Furthermore, when a pair of opposing rods works, the actuator has two modes of vibration under 1000 Hz. The resonant frequencies of the actuator are 522 Hz in Y direction and X direction. The results have proved that the actuator can realize varied 3-D displacement according to actual demands, and can be used in 3-D micron-scale field, such as surface mold polishing.

The differential magnetic field sensing is proposed to detect the position of the electrode tip for the smelting of the submerged arc furnace (SAF). The magnetic radiation model is established by the magnetic differences between the electrode zone and electric arc zone in the industrial field of SAF and the differential magnetic field sensing system is developed. The experiments are carried out under the environment of industrial field. When the relative distance between the two probes is appropriately set, the field test curve can accurately reflect the position of the electrode tip. Theoretical analysis and experimental results show that the difference of the front end of the system can detect the position of the electrode tip and effectively avoid saturating the system. Compared with the detection of magnetic field array sensing, the differential magnetic field detection scheme is more effective for the position information of the electrode tip and has better practical value for industrial measurement.

The design of a high-frequency transformer, which is the main component of a DC/DC converter, is very important. In the case of a DC transmission system, such as HVDC, the transformer should use high power and high frequency, but there are few studies in this category. Therefore, this study examined the design of a high frequency transformer. When designing the transformer covered in this paper, it is necessary to consider the frequency components differently from a traditional transformer design. Therefore, winding resistance, leakage inductance, and parasitic capacitance were calculated according to the frequency change, and finite element method (FEM) analysis and comparative analysis were conducted for validation.

For wireless charging, a misalignment between a receiver (Rx) coil in the devices (EV, drone and IMD) and a transmitter (Tx) coil often occurs. In this case, a mutual inductance between the coils changes, and consequently a power transfer efficiency (PTE) of the wireless power transfer (WPT) system also changes. To analyze the WPT system in such a situation, this paper presents an analytical method using Neumann formula to derive mutual inductance considering angular and position variations of two rectangular spiral coils. To verify the proposed method, magnetic resonant WPT systems of 85 kHz and 6.78 MHz are implemented, and the PTE values derived from the analyzed mutual inductance and the measured S-parameters are compared for the cases of angle and position variations. For each case, the two PTE values agree well with each other, and it is verified using the normalized root mean square error (NRMSE) values.

In addressing the needs of automotive radar designers, this study investigates the 77 GHz radar absorbing materials (RAMs) suitable for the automotive environment. A metamaterial structure is composed of metallic conductors of cross pattern on a grounded dielectric substrate (FR4). Computational tools (ANSYS HFSS 13.0) were used to model the interaction between electromagnetic waves and the metamaterial structures. The simulation output included the reflection coefficient. Another parameter of interest was the surface currents and electric fields, which were used to depict the resonating behavior of the metallic portions of the metamaterials. Magnetic resonance resulting from antiparallel currents between the strip conductors on front surface and ground bottom plane was observed at the frequency of minimum reflection loss (–23 dB at 77 GHz) with a small substrate thickness as low as 0.2 mm. The simulated resonance frequency and reflection loss can be explained well on the basis of the circuit theory of an LC resonator.

This study was conducted to investigate the effects of high frequency repetitive transcranial magnetic stimulation (rTMS) on walking and balance in Parkinson's patients. Fifteen subjects were randomly assigned to the experimental and control groups, and high-frequency rTMS was applied to the experimental group for 20 minutes per day, 5 times a week for a total of 4 weeks. The gait speed of the subject was evaluated by 10MWT, and the dynamic and static balance was evaluated using TUG and BBS. In the experimental group, significant improvement was observed in 10MWT, TUG, and BBS after intervention (p < 0.05), and there was significant improvement in 10MWT and BBS compared to the control group (p < 0.05). The results of this study suggest that high frequency rTMS applied to primary motor cortex (M1) positively affects walking and balance in Parkinson's patients.

Radiomics is a field for quantitative image assessment and research using a variety of sophisticated and complex algorithms by extracting a significant and numerous amount of specific functional elements (called texture feature) from medical images. It is mainly used in oncology and can provide a variety of capabilities in a noninvasive way, such as explaining the tumor phenotype, monitoring the response to treatment, comparing with normal tissue, diagnosing the prognosis of the patient and predicting survival. In this study, we will introduce of the workflow of radiomics and discuss the types of texture features, application of clinical cases, and the prospects of radiomics.