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As an important parameter in studies on vision and ophthalmology, pupil size directly controls the amount of the light entering the human eye. Pupilometers or eye tracking systems are used to measure the pupil size in some studies while a pupil size estimation model can be applied when actual measurement is not available, such as in cases of optical design, photobiological safety studies, etc. There are several existing pupil size estimation models, most of which reveal the relationship between pupil size and spatial distribution of luminance. However, the radial asymmetry of spatial luminance weighting function in horizontal and vertical directions and the effect of light chromaticity on the human eye were investigated. In this paper, experiments were conducted to reveal the asymmetry of the spatial weighting function in the horizontal and vertical directions and the effect of chromaticity on the pupil size. A unified pupil size estimation model is proposed based on spatially weighted corneal flux density and chromaticity coordinates. [ABSTRACT FROM AUTHOR]

The high temperature generated by the DC pantograph-catenary arc of urban rail systems will aggravate the wear of the pantograph-catenary system. When the ablation intensifies, it will lead to disconnection accidents on the contact line. In this paper, through the establishment of a pantograph-catenary arc model and contact line arc ablation model, considering the flow of the molten pool, it is reported that the temperature distribution of the pantograph-catenary arc is axisymmetric. With the increase in the arcing time, the maximum temperature of the arc increases. The heat flux density of the arc injection contact line presents a Gaussian distribution and is positively correlated with the arcing time. The high-temperature area of the contact line and the distribution of the molten pool show an approximate arc shape. The velocity of the molten pool shows a symmetrical distribution about the center of the electrode. The area, depth, and radius of the molten pool of the contact line increase with an increase in the arcing time, and the radius of the molten pool is always greater than the depth of the molten pool. The work presented in this paper is helpful to further our understanding of the basic physical process of pantograph-catenary arc ablation of contact lines. [ABSTRACT FROM AUTHOR]

This article, titled "Study on perceived brightness for display application and innovation," discusses the importance of understanding perceived brightness for display technology. Perceived brightness is influenced by environmental and psychological factors and differs from physical luminance. The paper explores how people perceive display brightness in different environments and the correlation between background luminance and panel luminance for see-through displays. The research aims to provide insights into how the human eye adjusts to different visual stimuli and environments and to guide the optimization of display luminance settings based on human needs. [Extracted from the article]

External-rotor dual-armature flux-switching PM (ER-DA-FSPM) machines have high torque density and decent fault tolerance, making them promising candidates for in-wheel machine applications in electric vehicles. The torque output and optimal design parameters of ER-DA-FSPM machines are affected by the stator/rotor torque ratio, which is the focus of this paper. Firstly, this paper analyzes airgap flux density harmonics of ER-DA-FSPM to provide a clear insight into the torque-generation mechanism. Then, this paper investigates the influence of torque ratio on average torque under the same copper loss. It is found that the average torque decreases with torque ratio increasing due to the reduction of the positive torque component generated by the sixth airgap field harmonics and the rise in the negative torque component from the eighth harmonics. Moreover, this paper also provides the optimal parameter recommendation to guide the machine design. The split ratio should increase, and the arc of PMs should decrease for a larger torque ratio, whilst the other parameters are hardly influenced. Next, this paper makes a comparison among the ER-DA-FSPM machine, external rotor flux-switching PM (ER-FSPM) machine, and surface-mounted PM (ER-SPM) machines. It shows that the ER-DA-FSPM machine, with the torque ratio being 2, can lead to a much larger total torque. In addition, in the event of rotor winding failure, which is more possible due to the existence of slip rings than stator winding failure, the stator can still provide an average torque larger than that of ER-SPM machine and 92.0% that of the ER-FSPM machine, respectively. Finally, the theoretical analysis is verified by the experiments. [ABSTRACT FROM AUTHOR]

The advent of diffraction‐limited storage rings (DLSRs) has boosted the brilliance or coherent flux by one to two orders of magnitude with respect to the previous generation. One consequence of this brilliance enhancement is an increase in the flux density or number of photons per unit of area and time, which opens new possibilities for the spatiotemporal resolution of X‐ray imaging techniques. This paper studies the time‐resolved microscopy capabilities of such facilities by benchmarking the ForMAX beamline at the MAX IV storage ring. It is demonstrated that this enhanced flux density using a single harmonic of the source allows micrometre‐resolution time‐resolved imaging at 2000 tomograms per second and 1.1 MHz 2D acquisition rates using the full dynamic range of the detector system. [ABSTRACT FROM AUTHOR]

The rotor loss of rare earth permanent magnet synchronous motor (PMSM) affects the efficiency and reliability of the motor and is an important research direction of rare earth permanent magnet synchronous motors. In this paper, the influence of rotational speed on the loss of the rotor core and the permanent magnet is analyzed through the analysis of the motor magnetic field and rotor loss calculation. Specifically, with the increase in rotational speed, the weak magnetic current increases, the amplitude of flux density change in the rotor core decreases, and the loss of the rotor core also decreases. The greater the influence of the harmonic current magnetic field on the outside of the rotor, the greater the loss. The core loss on the rotor is mainly distributed on the outside of the rotor. For further engineering applications, this paper analyzes the loss composition of three kinds of motors with different rotor structures and judges the optimal scheme based on the minimum loss. Finally, the correctness of this research is verified by comparing the experimental and simulation results of two kinds of motors with different rotor structures. The research content of this paper can provide a reference for the loss analysis and optimization and rotor structure selection of rare earth permanent magnet synchronous motor rotor design. [ABSTRACT FROM AUTHOR]

In this paper, a novel method to design and optimization of a 1.5 kW, 4-pole, 36-slot salient-pole permanent magnet synchronous machine (SPPMSM) based on a three-step skewed pole shoe method to reduce the output torque ripple and the cogging torque is investigated. In the first step, an initial model of the SPPMSM is designed, simulated, and verified through the Finite-Element method (FEM). The simulation results ensure the electromagnetic performance of the initial model of the machine under any operating conditions. Next, a novel method to re-design and optimize the SPPMSM based on a three-step skewed pole shoe shape is presented.. The significant results obtained from the optimized model of the SPPMSM are as: The output average torque and the air gap flux density are increased approximately by 12.65% and 3.33%, respectively compared to the initial design of the SPPMSM. The torque ripple is an important parameter in the design of the machine, and so, is decreased by about 16.03% which is equal to 10.41% in comparison with the initial model which is equal to 12.41%. The cogging torque in the initial model of the SPPMSM is equal to 0.036 N.m and with a 19.44% reduction, in the optimized model, it is 0.029 N.m. And finally, the back-EMF voltage of the SPPMSM is improved by 1.27% compared to the initial design model. [ABSTRACT FROM AUTHOR]

With the rise of eco-friendly policies, advanced motor technologies are being developed to replace fossil fuel-based engines in the mobility industry. Axial flux motors, known for their ability to reduce size and increase output torque compared to radial flux motors, require different materials and manufacturing techniques. Specifically, the production of complex stator cores and segmented magnets presents significant challenges, often leading to higher costs. To address this issue, soft magnetic composite (SMC) materials, which offer greater design flexibility, are being explored for use in stator cores. However, soft magnetic composite materials exhibit lower permeability and saturation flux density compared to laminated silicon steel, resulting in reduced output torque and efficiency. This paper investigates the effects of stator geometry on axial flux motor performance and explores cladding core technology, which combines soft magnetic composite materials with silicon steel. By conducting finite element method (FEM) analysis to evaluate the output torque and efficiency based on the shape of the silicon steel within the cladding core, this study proposes an optimized cladding core design to enhance the efficiency and output torque of axial flux motors. [ABSTRACT FROM AUTHOR]

In this paper, we extract distinctive determination for quasi magnetic flux of the quasi binormal magnetic flows of magnetic quasi $ \mathbf {b}^{\mathbf {q}} $ b q -particle by considering directional frame in 3D ordinary space. Also, we construct some advanced optical qualifications for magnetic quasi Lorentz flux for magnetic quasi- $ \mathbf {b}^{\mathbf {q}} $ b q particle along with the quasi directional frame fields. Then, we calculate quasi magnetic Lorentz flux with directional-quasi magnetic fields. Besides, we obtain original simulations with regard to directional potentials for directional-quasi magnetic binormal flows with Heisenberg optical ferromagnetic model. Magnetic optical flux surfaces are demonstrated in a homogeneous optical flux surface by fractional numerical and applied developments. By using above models, we get new fractional model with q-homotopy analysis transform method (qHATM) and its illustrative presentation to consider magnetic optical flux surface. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study on the morphology, structure, and luminescent properties of ceramics synthesized in the radiation field of MeWO4 compositions (where Me is Mg, Ca, and Zn). The synthesis of ceramics was carried out by the direct action of the electron flux on an initial mixture of powders of the given stoichiometric composition. WO3, ZnO, MgO, and CaO powders with particle sizes in the range of 1–50 microns were used for the synthesis of the samples. It was found that the yield of the radiation synthesis reaction (the ratio of the mass of the sample and the charge used), when treated with an electron flux with an energy of 1.4 MeV and a flux power density of 15–18 kW/cm2, was in the range of 75–99%. The synthesis of all compositions was carried out under the same radiation treatment modes, although the melting temperatures of the starting materials varied significantly and ranged from 1473 °C (WO3) to 2825 °C (MgO). The study of the ceramic structure showed that under the radiation effect of powerful radiation fluxes on the charge, a crystalline phase of the appropriate composition formed, regardless of the synthesis modes. The results of XRD studies show that during the radiation treatment of the charge, ceramics are formed mainly with the crystalline phases ZnWO4, MgWO4, and CaWO4. These resulting MeWO4 ceramics can be used for the same purposes as crystals. Photoluminescence (PL) and cathodoluminescence (CL) were studied under excitation using stationary ultraviolet radiation and nanosecond pulses of electron flux. In general, the PL and CL of synthesized ceramic samples ZnWO4, MgWO4, and CaWO4 showed that their luminescent properties are similar to those of luminescence in corresponding crystalline materials. This indicates the formation of a crystalline phase in synthesized ceramic samples. [ABSTRACT FROM AUTHOR]

The paper suggests a design and optimisation approach for a consequent‐pole line‐start permanent magnet motor (CPLSPM) with flexible pole arc coefficients and high utilisation of rare‐earth (RE) materials, without the need for a variable frequency drive. The presence of dual‐sided slots and adjustable pole arc coefficient sets CPLSPM apart from other types of motors, making the analysis of its cogging torque more complex. Taking into account the double‐sided slotted and flexible adjustable pole arc coefficient, a cogging torque and airgap flux density model was established, and the influence of the pole arc coefficient on the characteristics of the cogging torque and airgap flux density of CPLSPM was analysed. The authors conduct multidimensional optimisation considering the coupling of multiple parameters to obtain a CPLSPM with minimal RE material usage, low cogging torque and excellent start‐up and steady‐state performance. Finite element simulation data are presented to validate the factors affecting the cogging torque and the feasibility of the proposed less‐magnetic CPLSPM design. Finally, a prototype of a 750 rpm/2.2 kW CPLSPM is built, and performance testing is carried out for comparison, and applied to submersible mixers. [ABSTRACT FROM AUTHOR]

This paper proposes a high torque density dual-stator flux-reversal-machine with multiple poles Halbach excitation (MPHE-DSFRM), which uses two pole pairs' numbers (PPNs) of PM excitation on one outer stator tooth, and one PPN of PM excitation on one inner stator tooth. The introduction of different PPNs of PM excitation on the outer and the inner stators can optimize magnetic circuit and airgap flux density. A Halbach array is formed by inserting three pieces of circumferentially magnetized PMs into four pieces of radially magnetized permanent magnets (PMs) on the outer stator, which aims to further enhance torque density, and reduce torque ripple. Based on the flux modulation effect, the analytical modeling of the proposed MPHE-DSFRM is established, together with the evolution process, and the working principle is presented. Then, the key design parameters of MPHE-DSFRM are optimized to achieve high torque density and low torque ripple for high torque quality. Three representative DSFRMs and a conventional FRM are designed and analyzed, and they share the same design key parameters, including PM usage, outer radius of the outer stator, and active airgap length. The electromagnetic performances, including airgap flux density, back electromotive force (back-EMF), and torque characteristics, are analyzed and compared by finite element analysis (FEA). The calculated results show that the proposed MPHE-DSFRM can provide high torque density and high PM utilization. [ABSTRACT FROM AUTHOR]

In the last decades, magnetic brake has obtained a great intention to replace the commonly used frictional brake, especially in robotic applications. The working principles of magnetic brakes are simple, but designing magnetic brakes for a specific application is quite difficult and requires intensive research, large material resources, and costly processes, especially when a trial-and-error approach is used. This paper provides a method to design a magnetic brake that can stop a rotating disc at a specific time. In this study, a magnetic disc brake with four control parameters has been selected, with four levels for each control parameter. These control parameters are air gap width, electromagnet area, flux density, and Initial speed. The stopping time, where the angular velocity, the torque, and the dissipated power become negligible, has been measured. Taguchi method has been used to determine the order of the effect of each control parameter on the selected quantities. Furthermore, the study has used the multivariable linear regression model to confirm Taguchi method. As a case study, the parameters for the magnetic brake are tuned to make it able to stop the rotating disc at a specific time of 10 s. This paper shows that the most influential parameter on the time for the selected quantities to become negligible is the flux density, followed by the air gap width, the electromagnet area, and the Initial speed, respectively. Multivariable linear regression analyses validate the results of Taguchi method based on the data mean analyses. COMSOL Multiphysics 5.6 is used to simulate the magnetic brake under study, which is able to stop at 10 s, based on the results from Taguchi method and multivariable linear regression analyses. This paper will empower the design for a magnetic brake that can stop at a specific time according to its application, and that is by tuning the control parameters investigated in this study in a straightforward way. [ABSTRACT FROM AUTHOR]

Core loss estimation in switched reluctance motor is a complex task, due to non-linear phenomena and non-sinusoidal flux density waveforms. Several methods have been developed for estimating it (e.g. empirical, and physical-mathematic models), each one with merits and limitations. This paper proposes a new method for core losses estimation based on Finite Element Method Magnetics software. The main idea is using the machine phase-current harmonics as input for estimating core losses. In addition, a comparative study is carried out, where the proposed approach is faced up to a different one, based on Fourier decomposition of the flux density waveforms in the machine sections. In order to systematically analyze and compare the applied estimation cores loss techniques, a case study of a three-phase 6/4 SRM for different simulation scenarios is introduced. The outcomes of both methods are discussed and compared, where core loss convergence is found for limited speed and load ranges. [ABSTRACT FROM AUTHOR]

To study physiological reactions in the brain and skin of higher mammals exposed to chronic radiofrequency radiation, specific absorption ratio (SAR) determination is required and time-consuming numerical methods are used. The paper deals with the estimation of the whole-body specific absorption rate (SAR) in rats chronically exposed to external electromagnetic fields, as well as the development of a laboratory setup simulating the operation of a fifth-generation 5G New Radio base station (with a signal bandwidth of 15 MHz and a carrier frequency of 2.4 GHz). The paper presents a modified method for theoretical SAR estimation for one-sided irradiation and distributed absorption. Mean whole-body SAR values were estimated by the proposed method and numerically modeled with the CST Microwave Studio simulation software 2020package using primitive rat models. Dielectric parameters in the numerical simulation were used from the software library. The IEEE/IEC 62704-1 algorithm was used to investigate SAR in numerical simulations. The theoretical estimates and numerical simulations were compared for different SAR distributions and were found to be qualitatively comparable. The differences between approximate theoretical estimates and numerical simulations are 7% and 10% for distributed and non-distributed absorptions, respectively. The proposed method, which takes into account the decreasing power flux density, can be used to estimate the approximate whole-body SAR during chronic electromagnetic field exposure in rats. [ABSTRACT FROM AUTHOR]

This paper analytically investigates both the air gap flux density and the generated power of an Axial Flux Permanent Magnet Vernier Motor (AFPMVM). The AFPMVM has the same operational principle as a magnetic gear. It operates using space harmonics of the air gap flux density due to the magneto-motive force (MMF) and air gap permeance. This paper also examines the effect of various combinations of the rotor magnet pole pairs, stator slots, and winding pole numbers on the power factor and power density using the 3-D finite element method (3D-FEM). It is observed that, although having a higher pole ratio results in low cogging torque and high power density, it makes the machine length longer and has a lower power factor. Therefore, by employing the high pole ratios, the main advantage of the axial flux machines, i.e. having a shorter length, is sacrificed. [ABSTRACT FROM AUTHOR]

Brushless DC (BLDC) motors have gained popularity because of numerous advantages. This motor application is achievable Since permanent magnet (PM) technology has advanced. This motor has higher efficiency, reliability, and power density and requires less maintenance due to the absence of brushes. A higher torque-to-mass ratio and long life are two of this motor s most attractive characteristics, making it appropriate for highperformance applications. This study describes the hybrid methodology for analyzing a three-phase, four-pole, 1500 W, brushless DC (BLDC) motor with an inner rotor. This paper uses PI controllers and PWM in Matlab /Simulink and the chopped current control in Maxwell 2D. BLDC motor modeled by rotation machine export (RMxprt) analytical software and analyzed with a finite element method (FEM) Maxwell 2D software to calculate motor performance, such as torque, speed, and efficiency. The FEM results were verified by comparing them with the results taken from the Matlab/Simulink program and with the aid of the RMxprt software to supply some missing data. The results from Maxwell 2D and Matlab show good agreement. Despite lacking motor test data, this paper successfully applied a hybrid FEM-analytical approach to study a BLDC motor using three software packages RMxprt, Maxwell 2D, and Matlab/Simulink. The RMxprt program offers missing data like stator resistance, stator inductance, and torque constant. It is provided in the design sheet to help us with motor modeling. The successful adoption of the proposed hybrid FEM-analytical methodology will provide a good starting point for future BLDC motor research work. [ABSTRACT FROM AUTHOR]

In a 25-Hz phase-sensitive track circuit, traction backflow is unevenly distributed in the two rails, resulting in interference caused by the 50 Hz unbalanced current, which leads to misoperation of relays and other equipment in the circuit. Focusing on the mechanism of unbalanced current generation, this paper probes the causes of track circuit equipment interference and innovatively analyzes the mechanism of the choke transformer and relay affected, in order to find a method to suppress the interference of the 25 Hz phase-sensitive track equipment. Firstly, the mechanism of unbalanced current generation is explained, and the influence of the unbalanced impulse current on the choke transformer and binary two-bit relay is analyzed. Secondly, the DC magnetic bias, the second side voltage of the choke transformer and the excitation current, flux density, core loss of choke transformer and relay under a different unbalance impulse current are simulated. Then, the unbalanced current simulation test, unbalanced current test during driving and grounding wire test are carried out. Finally, it is concluded that the unbalanced impulse current causes magnetic saturation of the choke transformer, then affects voltage sag of the relay coil, resulting in misoperation of equipment. The conclusions of this paper can play an important guiding role in studying the influence of unbalanced current and restraining the interference of the 25 Hz phase-sensitive track circuit. [ABSTRACT FROM AUTHOR]

The paper presents results of calculating the RATAN-600 beam pattern (BP) and BP drift scans of point radio sources in the West Sector radio telescope operation mode at a frequency of 4.7 GHz. When calculating the BP, the properties of the radio telescope antenna system in this operation mode were taken into account: the use of a large secondary mirror, asymmetric radiation of the primary mirror, and the location of the primary feeds (feed horns) along the focal line of the secondary mirror. The shape of the calculated drift scans of sources through the BP is compared with that of the experimental drift scans of sources obtained from observations in the West Sector. The main characteristics of the drift scans are calculated and compared when the radio telescope operates with the West and North Sectors. A new method for determination of flux densities of sources passing through the BP outside its central cross-section is proposed, and its accuracy is estimated. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) is a technology that enables energy transmission without physical contact, utilizing magnetic and electric fields as soft media. While WPT has numerous applications, the increasing power transfer distance often results in a decrease in transmission efficiency, as well as the urgent need for addressing safety concerns. Metamaterials offer a promising way for improving efficiency and reducing the flux density in WPT systems. This paper provides an overview of the current status and technical challenges of metamaterial-based WPT systems. The basic principles of magnetic coupling resonant wireless power transfer (MCR-WPT) are presented, followed by a detailed description of the metamaterial design theory and its application in WPT. The paper then reviews the metamaterial-based wireless energy transmission system from three perspectives: transmission efficiency, misalignment tolerance, and electromagnetic shielding. Finally, the paper summarizes the development trends and technical challenges of metamaterial-based WPT systems. [ABSTRACT FROM AUTHOR]

An analytical method was proposed for obtaining the magnetic field distribution for surface-mounted permanent magnet machines with the structure of unequal magnetic poles. Firstly, the Laplace equation and Poisson equation were solved using the method of the separation of variables, and then the mathematical model of the motor structure with unequal magnetic poles was obtained. Secondly, according to the design parameters of the two types of prototypes motors, the flux density in the air gap region of the two types of prototypes motors was calculated, respectively. Thirdly, by comparing the results calculated using the analytical method with the results obtained using the finite element method, the analytical method proposed in this paper was proven to be effective. Moreover, the armature reaction field and the effect of the stator slotting were considered in the mathematical model as well. Overall, the analytical method presented in this paper provides a theoretical basis for the analytical calculation of motors with the structure of unequal magnetic poles. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to compare and analyze the electromagnetic characteristics of the basic structure of the coil in the electromagnetic coupling mechanism for the wireless power supply of permanent magnet motors in electric vehicles. The electromagnetic coupling mechanism is one of the key technologies for wireless power transmission and the coil structure plays a key role in the transmission performance of the coupling mechanism, and different structures can achieve different performances. The central objective of coil structure studies is to investigate how the coupling coefficient can be increased to achieve greater transmitted power and higher efficiency. In this paper, we investigate two basic coil configurations, circular and square, by studying their flux density variations when used as transmitting coils and their electromagnetic coupling characteristics when used as receiving coils. Three couplers consisting of circular and square coils are also analyzed in simulations and experiments are carried out on couplings containing circular and square coils of the same area. The results of the study show that the qualitative analysis, simulation analysis and experimental results are in high agreement. The results of this paper are an important reference for the design and optimization of wireless power coils for permanent magnet motors in electric vehicles. [ABSTRACT FROM AUTHOR]

In this paper, the boundary discretization method is used to improve the traditional subdomain model. The improved model can be used to calculate the magnetic field distribution in the region containing non-orthogonal boundary, avoiding the influence of the simplified stator slot or permanent magnet shape on the results in calculating the motor magnetic field using the traditional subdomain model. In addition, the improved subdomain model can also be used to calculate the air-gap flux density when the rotor is eccentric, instead of segmenting the air-gap to an equivalent state without eccentricity. The calculation object of this paper is a surface-mount permanent magnet motor with a rectangular stator slot. The air-gap flux density under no-load and load conditions is calculated, respectively. Since the improved subdomain model does not need to simplify the stator slot shape, the magnetic potential in the stator slot is also calculated. Finally, the air-gap flux density under rotor eccentricity is calculated, and the influence of the calculating parameters on the results of the improved subdomain model is discussed. All the calculated results are compared with those obtained by the finite element method, which verifies the accuracy of the improved calculation model. [ABSTRACT FROM AUTHOR]

One of the early design decisions for DC‐DC converters is the choice of an appropriate magnetic core material. Powder cores in particular are suitable due to their saturation flux density of up to 1.5 T. However, high DC currents constitutes a significant problem since the winding cross‐section rises with the current, which consequently increases AC losses due to skin effects. Another challenge is the reduction of winding layers to decrease proximity losses. This paper presents an improved single‐layer winding design procedure for DC‐DC converter powder cores. The procedure determines the optimum number of parallel cores and stacks. This way, the procedure enables a predefined maximum wire cross‐section for copper loss optimisation and single‐layer winding. The introduced approach defines the optimum switching frequency as a trade‐off between core loss and core volume. Finally, experimental tests with two setups validate 27 kW DC‐DC converters and hence the design procedure using Si‐IGBTs and SiC‐MOSFETs. The results demonstrate that SiC‐MOSFETs reduce core volume by a factor of 3 compared to Si‐IGBTs. Further, the SiC setup reaches high efficiencies of up to 98.53% compared to 98.17% for the Si‐based converter. [ABSTRACT FROM AUTHOR]

Despite continuous effort to minimize torque ripple, the reduction of vibration has not been yet achieved due to the lack of link between these two performances. The difficulty of investigating the relationship stems from the fact that torque is solely influenced by tangential force whereas vibration is directly tied to radial force. In this paper, the correlation between torque ripple and vibration in an IPMSM (Interior Permanent Magnet Synchronous Motor) is established by examining the air-gap flux density in both radial and tangential directions. Its temporal and spatial harmonics are analyzed. A six-pole nine-slot IPMSM is used as a base configuration, and the air-gap flux density is varied by changing the height of a stator tooth tip. In the previous study, the same approach has been done to observe how to reduce torque ripple effectively. In this study, however, it is found that the trend of torque ripple is not the same as that of vibration with respect to the height of a pole tip, and the relation between the two is thoroughly observed and explained. [ABSTRACT FROM AUTHOR]

In this study, the inductor optimization design is performed by applying the Pareto optimization technique. As environmental problems emerge, the electric vehicle market is expanding, and accordingly, volume reduction and high efficiency of the onboard charger (OBC) are required. An OBC consists of a PFC stage and a DC/DC stage. The inductor is a major component in a converter and affects the volume and efficiency of the entire converter system. However, reducing the volume of the inductor leads to an increase in loss due to an increase in the change in flux density. Therefore, it is important to derive a suitable design for the target between the two parameters in the trade-off of loss and volume. This paper introduces the optimal design algorithm for boosting inductors of PFC converters in terms of volume and loss. Volume and loss are difficult to compare with each other, making it difficult to set weights. Therefore, Pareto optimization was applied which can be selected according to the needs and purposes of the decision-maker, without weighting as an optimization method. Through a series of procedures of applying Pareto optimization to the inductor design, several optimal inductor designs can be derived. At this time, the optimal designs become a set of designs in which the loss does not decrease without an increase in volume, or the volume does not decrease without an increase in loss. A designer can select a design with an appropriate volume and loss that meets the purpose of the design or preference. Therefore, through the proposed method, the inductor can be flexibly designed according to the target of the application. The proposed algorithm is applied to the interleaved totem-pole bridgeless boost PFC converter, to review its effectiveness. As a result, several inductor designs are derived in the search space, and various optimal designs are visualized through the Pareto Frontier. This facilitates comparative analysis of various inductor designs and helps designers select reasonable inductors. The validity was verified by selecting one of the obtained optimal inductor designs and driving the experiment with the resulting inductor. [ABSTRACT FROM AUTHOR]

We identify a source (J1507+3013) with an extended diffuse radio emission around an elliptical galaxy from the Very Large Array (VLA) Faint Images of Radio Sky at Twenty-cm (FIRST) survey. J1507+3013 possesses a morphology similar to the recently identified circular, low-surface-brightness, edge-brightened radio sources commonly known as odd radio circles (ORCs). Such diffuse emissions, as reported in this paper, are also found in mini-haloes and fossil radio galaxies, but the results presented here do not match the properties of mini-haloes or of fossil radio galaxies. The extended emission observed in J1507+3013 around an elliptical galaxy is a very rare class of diffuse emission that is unlike any previously known class of diffuse emission. The extended diffuse emission of J1507+3013 is also detected in the Low Frequency Array (LOFAR) at 144 MHz. J1507+3013 is hosted by an optical galaxy near the geometrical centre of the structure with a photometric redshift of z = 0.079. The physical extent of J1507+3013 is approximately 68 kpc, with a peak-to-peak angular size of 44 arcsec. It shows significantly higher flux densities compared with previously discovered ORCs. The spectral index of J1507+3013 varies between −0.90 and −1.4 in different regions of the diffuse structure, which is comparable to the case for previously discovered ORCs but less steep than for mini-haloes and fossil radio galaxies. If we consider J1507+3013 as a candidate ORC, then this would be the closest and most luminous ORC discovered so far. This paper describes the radio, spectral, and optical/IR properties of J1507+3013 in order to study the nature of this source. [ABSTRACT FROM AUTHOR]

Nanocrystalline core is widely used in the design process of high-frequency transformers and inductors due to the attractive magnetic properties of nanocrystalline material. However, the flux density distribution is nonuniform in the core because the reluctance is closely related to its geometric shape. The nonuniformity of flux density distribution may cause huge calculation errors of core losses. In this paper, Finite Element Method (FEM) is used to justify taking into account nonuniform distribution of flux density during the process of core loss calculation. An improved loss separation equation considering nonuniform distribution of flux density is proposed, and the improved equation is verified through calculating and analyzing the losses of nanocrystalline cores with different wound thicknesses. Compared with the traditional loss separation equation, the accuracy is improved, and the average error of improved equation is confined in 10%. [ABSTRACT FROM AUTHOR]

Ledderhose disease (LD, or plantar fibromatosis) is a rare, nodular, hyperproliferative condition affecting the plantar aponeurosis of the foot. At present, several conservative, non-surgical treatments have been documented, although with various degrees of success, with little evidence in the literature supporting their efficacy. In this scenario, extracorporeal shock wave therapy (ESWT) has emerged as a safe, effective, and less invasive approach for the successful treatment of several refractory musculoskeletal conditions and soft tissue injuries. Again, recent experimental evidence has shown that ESWT can exert beneficial effects on different fibroproliferative diseases, including Dupuytren's and Peyronie's disease. In contrast, the literature regarding the use of ESWT for LD is extremely limited, and no optimal application parameters have been defined to ensure its effectiveness for this disease. Therefore, in the present paper, we report a case of a 48-year-old male patient who developed bilateral foot LD, which was successfully treated with a novel ESWT protocol of treatment consisting of three sessions at 1-week intervals, with 2000 impulses at 5 Hz with an energy flux density of 0.20 mJ/mm2. Our data show that this ESWT treatment protocol was effective in completely relieving pain, restoring full functional activity, and thus, greatly improving the patient's quality of life. [ABSTRACT FROM AUTHOR]

This paper presents a study of bidirectional permanent magnet excited machine (BPMEM) based on the study of field-modulation permanent magnetic gear machine (FPGM). The BPMEM structure includes the installation of consequent-pole permanent magnets (PMs) on both the stator and rotor sides of the FPGM so that the stator and rotor can be bidirectionally excited to increase the working airgap flux density amplitude, reduce the flux leakage between poles, and increase the torque density. Therefore, the paper first analysis the influence of different airgap structures and PM arrangements on the airgap flux density and studies the winding slot–pole combination and the resulting working flux density harmonics to analyse the electromagnetic torque generation mechanism. By using the finite element analysis (FEA), the quantitative analysis and comparison of the FPGM, slot-wedge-less FPGM (SWL-FPGM), consequent-pole FPGM (CP-FPGM) and BPMEM verify the superiority of BPMEM in improving electromagnetic torque. In addition, the paper also studies the key performance of BPMEM's overload capacity, power factor and flux-weakening capability. Finally, no-load and independent load experiments are carried out on the FPGM prototype to verify the correctness of the FEA model and analysis method of the machine in this paper. [ABSTRACT FROM AUTHOR]

This article presents the comparison of 3D and 2D finite element models of a power transformer designed for reactive power compensation stations. There is a lack of studies in the literature on internal electromagnetic phenomena in the active part of a transformer operated in these conditions. The results of numerical 2D and 3D calculations of no-load current and losses in the transformer core were obtained by using various methods and models. The impact of considering the hysteresis loop phenomenon on the calculation of core losses was investigated by using the Jiles–Atherton core losses model. The results obtained in the paper show that the model of the core must contain the areas representing the influence of overlappings on the no-load current and also on the flux density field in the core. The capacitive load of the transformer increases the flux density in the core limbs by several percent, so the power losses there must also increase accordingly. As a summary of the research, differences in the values of losses in each core element between the capacitive load and no-load conditions are presented. The results presented in this paper indicate that considering nonlinearity related to the magnetic hysteresis loop has a significant impact on the calculation of the core losses of power transformers. [ABSTRACT FROM AUTHOR]

An eccentric harmonic magnetic gear (EHMG) is better suited for situations requiring larger transmission ratios than magnetic-field-modulated magnetic gears. In the meantime, to increase the torque density even further, a new structure for EHMGs is presented in this paper. The stator's permanent magnets (PMs) are irregularly distributed, while the rotor's PMs are applied to a fan-shaped structure. Moreover, a Halbach array is adopted in both the rotor and the stator. A two-dimensional finite element (FE) model of the proposed EHMG is developed, and the flux density distribution and torque of the EHMG are calculated and verified via FE analysis. When compared to a conventional EHMG, the presented model's torque increases from 38.04 Nm to 50.41 Nm. In addition, for the sake of avoiding the oscillation and noise caused by resonance, a modal analysis of the proposed model is conducted and the consequences show that it has better antivibration properties. Finally, a prototype is made, a test bench is established, and the correctness and effectiveness of the proposed model are verified. [ABSTRACT FROM AUTHOR]

The theory of adiabatic electron transport in a correlated condensed-matter system is rooted in a seminal paper by Niu and Thouless [J. Phys. A: Math. Gen. 17, 2453 (1984)]; I adopt here an analogous logic in order to retrieve the known expression for the adiabatic electronic flux in a molecular system [L. A. Nafie, J. Chem. Phys. 79, 4950 (1983)]. Its derivation here is considerably simpler than those available in the current quantum-chemistry literature; it also explicitly identifies the adiabaticity parameter, in terms of which the adiabatic flux and the electron density are both exact to first order. It is shown that the continuity equation is conserved to the same order. For the sake of completeness, I also briefly outline the relevance of the macroscopic electronic flux to the physics of solids and liquids. [ABSTRACT FROM AUTHOR]

The iron loss of doubled-sided linear switch reluctance motor (DLSRM) is analyzed and calculated in this paper. Because of the double salient structure of the switched reluctance motor and the nonlinearity of the magnetization curve of the ferromagnetic material, the flux density waveform is nonsinusoidal. So, it is difficult to calculate the iron loss of DLSRM. This paper mainly introduces the calculation method of dynamic magnetic density of the DLSRM, and basing on this, the simulation model of iron loss of DLSRM is built and compared the iron loss in different parts of the total as a percentage of the motor. Finally, an experimental platform based on DLSRM is built to measure the actual iron loss in the motor and verify the correctness of the calculation of iron loss. [ABSTRACT FROM AUTHOR]

The paper is devoted to the analysis of the observation results with the single-mirror radio telescope RT-22 (PRAO, LPI) in the water vapor maser line at 22 GHz in the direction of dust clumps from the ATLASGAL and Bolocam large-scale blind surveys in the millimeter continuum. The aim of this paper is to search for masers in the water vapor line in previously unexplored sources and to study the variability of known masers. Observations of 140 sources resulted in the detection of maser emission at 22 GHz in six sources, and in four sources (ATLASGAL 016.987+00.981, 017.216+00.821, 018.701–00.229, and Bolocam 081.174–00.100) masers were detected for the first time. In two sources (ATLASGAL 034.195–0.592 and Bolocam 081.174–0.1), the water vapor line masers showed significant variability during the 8-month observation and follow-up program. Comparison of RT-22 observational data with archival data from the GBT‑100 telescope (US National Radio Astronomy Observatory) showed that 9 out of 140 sources show a significant change in the radiation flux density of masers: two sources changed from the category of masers with low brightness ( Jy) to the category bright (more than 10 Jy), and in seven relatively bright earlier (more than 3 Jy) masers, no radiation was detected. Significant changes in the characteristics of the maser emission may indicate changes in the environmental conditions in which the maser emission was produced, which is of interest for further study of maser-related processes. [ABSTRACT FROM AUTHOR]

The armature is an important part affecting the energy conversion efficiency of a reluctance accelerator. In this paper, six kinds of soft magnetic materials are chosen and four structures are designed for the armature. At first, the circuit and magnetic force are theoretically analyzed. Then the armatures with different materials and structures are used in the simulation, and the performances are compared and analyzed. At last, the experiment verifies the theory analysis and simulation design. It is concluded that the saturation flux density and conductivity of the material are the key factors affecting the armature force, and the optimization of armature structure can effectively restrain the eddy current, reduce negative force and improve efficiency. Compared with cutting slits in solid armatures, laminating the sheets radially can reduce the eddy current more efficiently. Although slitting can prevent the eddy current to a certain extent, meanwhile, it will decrease the magnetic force because of the losing of magnetized volume and the surface area. Hence, choosing the high saturation flux density material and making out the armature with radially_laminated sheets will improve the efficiency of the reluctance accelerator. In this paper, the silicon steel radially_laminated armature is a better choice for the armature design of the reluctance accelerator. [ABSTRACT FROM AUTHOR]

The space-time kinetics of ADS Subcritical Reactor (ADSR) under beam transients play an important role in ensuring the reliability of the control and safety system of the accelerator-driven subcritical system (ADS). In order to elucidate the effect of high heterogeneity of neutron flux density in space-time on the neutron space-time kinetics of ADSR under different subcriticality and beam transients, in this paper, the multimode core few-group constants, which is more adaptable to the beam transients, is used to investigate the mechanism of neutron flux density, core few-group constants, and kinetic parameters of ADSR under the synergistic effect of external neutron source, subcriticality, and the beam transients. The results show that with the deepening of the subcriticality, with the increasing role of external neutron source, the neutron flux density of the ADSR has a higher heterogeneity of space-time, which leads to a larger difference in the core few-group constant library of different modes, and thus a larger difference in the kinetic parameters (especially the neutron generation time) of different modes. Therefore, in the study of the influence mechanism of neutron space-time kinetics of ADSR under beam transients, the multimode core few-group constants should be used, and the influence of external neutron source and subcriticality on the kinetic parameters, especially the neutron generation time, should be emphasized. [ABSTRACT FROM AUTHOR]

A serious inrush current may occur when a power transformer is re-energized, which will cause many adverse effects on power equipment and the power grid. The corresponding potential hazards can be reduced if the existing residual flux density (Br) can be accurately measured. Combined with the field-circuit coupling analysis method, a novel method for measuring the Br based on the phase difference between the applied AC voltage and resulting transient current is proposed in this paper. When the same AC voltage is applied to the transformer winding, the Br affects the resulting transient current. The phase difference between the applied voltage and the resulting current can be calculated by the cross-correlation technique. Based on the finite element method (FEM), the empirical formula for the quantitative measurement of Br in the transformer core is determined. Finally, an experimental study is performed on the square core of single-phase transformers. The experimental results reveal that the proposed measurement method is with high accuracy. [ABSTRACT FROM AUTHOR]

This paper presents a fast analytical model for estimating the components of the PM flux density distribution in the air-gap for a number of interior permanent magnet synchronous machines (IPMSMs). Deriving the two-dimensional (2-D) analytical model for IPMSMs is more challenging compared to that of surface-mounted permanent magnet synchronous machines (SPMSMs) due to the inconsistent geometry of the rotor in polar coordinates. IPMSMs are usually modeled by using 0-D or 1-D methods such as the magnetic equivalent circuit (MEC); however, the MEC method is unable to take into account the tangential component of the magnetic flux density vector. In this paper, a 2-D analytical no-load electromagnetic model for five rotor topologies of IPMSMs is proposed. The effects of the stator slots on the radial component of the PM flux density distribution in the air-gap are then included by defining an air-gap function. The effects of the stator slots on the tangential components of the PM flux density distribution in the air-gap are also considered by injecting virtual surface currents (VSCs) or virtual permanent magnets (VPMs). For verification purposes, the analytical results are compared with those of the finite element method (FEM) and the experimental results of one of the cases. [ABSTRACT FROM AUTHOR]

Gallium nitride high-electron-mobility transistor (GaN HEMT) power devices are favored in various scenarios due to their high-power density and efficiency. However, with the significant increase in the heat flux density, the junction temperature of GaN HEMT has become a crucial factor in device reliability. Since the junction temperature monitoring technology for GaN HEMT based on temperature-sensitive electrical parameters (TSEPs) is still in the exploratory stage, the TSEPs' characteristics of GaN HEMT have not been definitively established. In this paper, for the common steady-state TSEPs of GaN HEMT, the variation rules of the saturation voltage with low current injection, threshold voltage, and body-like diode voltage drop with temperature are investigated. The influences on the three TSEPs' characteristics are considered, and their stability is discussed. Through experimental comparison, it is found that the saturation voltage with low current injection retains favorable temperature-sensitive characteristics, which has potential application value in junction temperature measurement. However, the threshold voltage as a TSEP for certain GaN HEMT is not ideal in terms of linearity and stability. [ABSTRACT FROM AUTHOR]

Magnetic fields in transformer cores are typically assumed to be one-dimensional fields, thus allowing magnetization processes to be regarded as axial magnetization. However, in the core corners or T-joint points of medium- and high-power rating transformers, the magnetic lines have different directions with respect to the rolling direction. This paper describes a method that allows changes in the flux density of transformer steel sheets to be calculated for any magnetization direction. These changes are assumed to depend only on certain limiting hysteresis loops assigned separately to the rolling and transverse directions of a tested transformer sheet, where these loops depend on the magnetization direction on the sheet plane. The selection of coefficients that define the limiting hysteresis loops for several magnetization directions is described, and the condition for the flux density saturation is considered. The resultant flux density in a specified magnetization direction is the geometric sum of the corresponding flux densities assigned to both the rolling and transverse directions. The limiting and partial hysteresis loops determined based on the proposed method for several magnetization directions are compared with analogous measured loops. Additionally, a comparison of the calculated hysteresis loops with loops showing changes in the resultant flux density for several magnetization direction is presented. [ABSTRACT FROM AUTHOR]

In this paper, an integrated micro-fluidic heat dissipation system with self-closing loop is designed in the cavity of power module to improve the heat dissipation of high heat flux power bare chip. The bare chip eutectic is welded to the diamond, and then the diamond eutectic is welded to the power module cavity, effectively reducing the thermal conduction resistance between the bare chip and the power module cavity. The impacts of microchannel configuration and channel width on heat dissipation capacity are investigated through experiments and simulation. Our results show the cross- linked microchannel exhibits better hat dissipation in identical circumstances. Moreover, the reduction of the channel width further improves the temperature performance of chips. The simulation results are highly consistent with the experimental results with a maximum deviation of 7.16% . The micro-ffuidic heat dissipation system proposed in this paper demonstrates fairly excellent performance, reaching maximum heat flux density of 320 W/cm² at a temperature of 70 °C. [ABSTRACT FROM AUTHOR]

The paper intends to study the magnetic losses of non-oriented electrical steel laminations under sinusoidal voltage supply. The measurement of magnetic losses of electrical steel laminations in Epstein Frame is implemented step by step at frequency range from 50 Hz. The calculation of the magnetic losses is made by using two methods based on the statistical loss model. Our contribution consists on the first model which corresponds to the curve fitting method which needs many experimental data but allows a better exactitude. The second method is defined in a time domain, in order to account of the presence of harmonics in the flux density wave form. The coefficients of the second method are determined from the curve fitting. A good agreement between practice and theory was established with these two methods. [ABSTRACT FROM AUTHOR]