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This article proposes a design method of the high-speed multilayer interior permanent magnet synchronous motor (HSML IPMSM) employing the ferrite permanent magnet (PM). Since the maximum speed of the traction motor in this article is 15 kr/min, the mechanical stability must be considered. Additionally, in the case of the HSML IPMSM, as the number of the PM layers increases, the thickness of the PMs must be reduced to be mechanically stable. On the other hand, because the ferrite PM has a relatively low coercive force compared with the Nd PM, an irreversible demagnetization of the ferrite PM of the HSML IPMSM is likely to occur. Therefore, the mechanical stability and irreversible demagnetization must be considered at all design steps. As the irreversible demagnetization and mechanical stability can be confirmed only by the finite-element analysis (FEA), the proposed method in this article is a design method that considers the irreversible demagnetization and mechanical characteristics at all design steps using the FEA. After the design of the traction motor is completed using this design method, the designed motor is manufactured. To verify the validity of the design method, experiments are conducted on the manufactured motor, and the test results are compared with FEA results.

Owing to the high speed and frequency required in electric machine industry, the significance of ac resistance has been increasing. This study investigates the ac resistance of windings according to the configuration of strands. The mechanism of generating the ac resistance in winding conductors was investigated with respect to the slot leakage flux and eddy current. Then, when applying the strands to the winding, the concept of unbalanced impedance was introduced to characterize the additional ac resistance due to circulating current. The analytic method to calculate ac resistance describing the above phenomena is derived and verified by FEA results. Afterward, the ac resistances of varying numbers and arrangements of strands were separately studied via finite element analysis. In addition, a method to avoid increasing the ac resistance was suggested based on impedance equalization when applying strands. Finally, experiments were conducted to verify the effect of the strand configuration on ac resistance. An E- and I- shaped core, which can be the rendering of common electric machines, such as motors, generators, and transformers, was manufactured and tested with winding specimens. Consequently, the test results showed a similar trend as the analytical results.

BACKGROUND Incomplete recovery of neuromuscular blockade is a common postoperative adverse event in the postanaesthesia care unit. OBJECTIVE We examined and compared the incidence of residual neuromuscular blockade when the recommended dose of neostigmine or sugammadex was administered according to a qualitative nerve stimulator response. DESIGN A randomised controlled trial. SETTING A tertiary care hospital in South Korea from September 2017 to November 2017. PATIENTS Eighty patients aged between 18 and 69 years were included in this study. All were patients scheduled to undergo elective laparoscopic cholecystectomy and who had an American Society of Anaesthesiologists physical status of one or two were eligible. INTERVENTIONS Patients were allocated randomly to receive neostigmine or sugammadex at the end of surgery. The doses of the reversal agents were based on the response to peripheral nerve stimulation, which was discontinued after administration of the reversal agent. MAIN OUTCOME MEASURES The primary outcome was the incidence of postoperative residual neuromuscular blockade. The secondary outcomes were the incidences of symptoms or signs of residual neuromuscular blockade such as hypoxaemia, inability to maintain head-lift for 5 s and diplopia. RESULTS The incidence of residual neuromuscular blockade on arrival in the recovery room was 44.4% in the neostigmine group and 0% in the sugammadex group (P

In order to improve the torque density of the magnetic flux concentrated permanent magnet synchronous motor utilizing a ferrite permanent magnet, it is important to reduce the leakage magnetic flux flowing through the rotor core. For satisfying the robustness of the rotating body and improving the torque density, we propose a structure in which two types of cores with different shapes are cross laminated. The proposed rotor structure consists of a core with a bridge that is necessary to maintain the rigidity of the rotor assembly, and a rotor assembly by cross laminating the segment-type rotor cores necessary for minimizing the leakage flux as well as improving the torque density. The complex three-dimensional (3-D) magnetic circuit of the cross-laminated rotor assembly has been modeled as a two-dimensional (2-D) model on the mathematical basis of an equivalent magnetic circuit. Using the equivalent 2-D model, the design of the cross-laminated rotor shape and the electromagnetic characteristics were examined comprehensively. At the same time, mechanical stresses due to centrifugal force and torque transmission between rotor core and shaft were examined. Finally, after the prototype was fabricated, the analysis and design methods were verified through no-load and load tests.

In this paper, the design of the concentrated flux-type synchronous motor (CFSM) using ferrite permanent magnets to improve torque is proposed for an automotive chassis actuator. The thin pancake type CFSM of this paper has considerable axial magnetic leakage flux due to structural reasons. It is, therefore, necessary to improve the torque. In order to meet the required specifications in a constrained installation space, this paper proposes two methods for torque improvement. The first method is the alternate-stacking core as this structure removes the magnetic leakage flux path. The second method is the rotor overhang that increases the air-gap flux density. Furthermore, the structures require a three-dimensional (3-D) finite element method (FEM) analysis for accuracy. However, to analyze the characteristics easily and quickly, the 3-D structure is made into the equivalent 2-D FEM through an analytical method using an equivalent magnetic circuit. Finally, in this paper, the validity of the design process and the effectiveness for torque improvement is verified through experiments.

This paper describes a method to reduce the torque ripple for the Wound Field Synchronous Motor, which does not use a permanent magnet. When a WFSM is used in an Integrated Starter Generator system, it must have a higher power density than other automotive motors in order to satisfy the size constraints and required power. An increase in the power density creates a magnetic flux saturation in the rotor, and this soon becomes the cause of an increase in the torque ripple of motor. An increase in the torque ripple can degrade the Noise Vibration Harshness characteristics of automotive by creating vibration and noise in the engine start-up mode, in which the maximum torque is generated in an ISG system. This paper proposes a method of reducing the torque ripple via a design that uses a flux barrier model in the WFSM’s rotor. The Response Surface Method is used to optimize the flux barrier model, and Finite Element Method is used to to verify the torque ripple reduction.

This paper proposes a novel structure for the concentrated flux-type synchronous motor (CFSM) in order to improve the torque density, as well as the vibration characteristics. First, the conventional surface-mounted permanent magnet synchronous motor as prototype for the electric booster in the brake system is investigated through tests. Then, the relationship between the vibration characteristics and the number of poles and slots is analyzed. Based on the analysis results, a pole–slot combination for an improved CFSM is determined to enhance the vibration characteristics. Furthermore, a novel structure for the improved motor that employs three different core shapes in the rotor is proposed to increase the torque density. As a result, the improved motor with excellent vibration characteristics as well as a high torque density is designed. Finally, experiments are conducted to verify the effectiveness and the feasibility of the proposed method.

A growing body of experimental work suggests that magic angle twisted bilayer graphene exhibits a "cascade" of spontaneous symmetry breaking transitions, sparking interest in the potential relationship between symmetry-breaking and superconductivity. However, it has proven difficult to find experimental probes which can unambiguously identify the nature of the symmetry breaking. Here we show how atomically-resolved scanning tunneling microscopy can be used as a fingerprint of symmetry breaking order. By analyzing the pattern of sublattice polarization and "Kekul\'{e}" distortions in small magnetic fields, order parameters for each of the most competitive symmetry-breaking states can be identified. In particular, we show that the "Kramers intervalley coherent state," which theoretical work predicts to be the ground state at even integer fillings, shows a Kekul\'{e} distortion which emerges only in a magnetic field., Comment: added a citation a note

In this paper, a design method for a wound field synchronous motor (WFSM) employing the dual stator winding and the winding connection change circuit is proposed. Through the design method, the WFSM can be operated as two different modes, and each mode is determined by the connection between the stator windings U, V, W and X, Y, Z. By applying the proposed method to the conventional WFSM, the operation mode of the motor is changed at a certain speed. The speed for the mode change is determined to maximize the efficiency of the machine. As a result, through the mode change, the line to line induced voltage, current phase angle, and phase resistance are decreased. In addition, the demand field current is also reduced to achieve the required torque due to the salient pole characteristics of WFSM. Consequently, the efficiency of the WFSM is increased due to the mode change. Finally, the effect of the proposed method and the validity of the simulation results are verified by the load test.

The harmonics of the induced voltage under load conditions cause the deterioration of the motor performance. It occurs when the peak value of the demand voltage exceeds the DC link voltage. In this paper, thus, to reduce the induced voltage harmonics under load conditions, an asymmetric rotor design method using the advanced inverse cosine function (AICF) is proposed. Using this method, the rotor shape is determined by considering the armature reaction under certain load condition. As a result, an improved concentrated flux synchronous motor (CFSM) achieving the required performance is designed. Lastly, the induced voltages waveforms of the proposed motors under the load conditions are compared through finite-element analysis (FEA) as well as experiments.

This study presents a design method to obtain an innovative structural design of a magnetising fixture that can achieve a target magnetisation orientation for a ring-type magnet of a surface-mounted permanent magnet (SPM) motor. The optimisation problem is formulated to minimise the integrated value of the difference between the magnetic flux distribution, produced by the input current of the magnetising fixture, and the target orientation that improves the torque performance of SPM motor. Two level set functions are employed to express both the structural boundaries and the material properties of the ferromagnetic material and coil comprising the magnetising fixture. The optimal shape of the fixture is obtained by using an adjoint design sensitivity and a time evolution equation for each level set function. To confirm the effectiveness of the proposed method, it is applied to a magnetisation problem for an 8-pole 12-slot SPM motor designed for a battery cooling system in a hybrid electric vehicle.

In order to improve the performance of the wound field synchronous motor (WFSM), the permanent magnet assist (PM-assist) is investigated in this paper. The effect of the PM-assist is dependent on the inserted position of the PMs. Thus, four models whose PMs are inserted at each different position are suggested. Then, the most effective position of the PM is decided by the mean torque per employed amount of the PM. By inserting the PMs into the decided position of a WFSM designed for a small electric vehicle traction, the PM-assisted WFSM is designed. By comparing the torque and the efficiency of the original WFSM and the PM-assisted WFSM, the effectiveness of the PM-assist is figured out. Finally, the validity of this research is verified by the experiment using the manufactured WFSM.

The aim of this study was to find the optimal table height to facilitate insertion of the spinal needle at a 90° angle and to reduce the anesthesiologist's discomfort. Sixty patients were randomly allocated according to landmarks on the anesthesiologist's body: umbilicus (group U), lowest rib margin (R), xiphoid process (X), and nipple (N). The coronal insertion angle between the patient's skin and the spinal needle was obtuse in groups U and R, and 90° in group X. We demonstrated that high operating tables at the xiphoid and nipple level facilitate more optimal needle entry angles while reducing the discomfort and joint flexion of anesthesiologists during spinal anesthesia.

This paper proposes an advanced method to satisfy both the stability and charging/discharging time constant requirements of second generation high-temperature superconductor (2G HTS) magnets. This novel method entails installing metal–insulator transition (MIT) material between the turns of the 2G HTS magnets. The MIT material acts as an insulator when the temperature is lower than a certain value. Above this temperature, the MIT material becomes a conductor. This transition can be used as a switch between the turns of the 2G HTS magnets. We refer to this temperature-dependent smart switch as “smart insulation.” Considering the operating temperature, we selected V2O3 as the material for smart insulation. We have experimentally verified that the advantages of both the insulation magnet (in the superconducting state) and no-insulation magnet (during quenching) can be simultaneously realized.

In this paper, the characteristics analysis of the surface-mounted permanent-magnet synchronous motor is carried out using the method of reflecting the axial leakage magnetic flux into the 2-D finite-element analysis (2-D FEA), and the result is discussed. For the method of projecting the axial leakage flux on the 2-D plane, the permeance coefficient was introduced. By using the proposed method, the parameters such as d- and q-axes inductance and linkage flux for d- and q-axes equivalent circuit analysis were calculated, and the characteristics analysis was performed. In order to verify the effectiveness of the proposed 2-D FEA, a speed versus torque experiment was performed and compared with the analysis results.

Large amounts of harmonics are contained in the current as the motor is driven by pulse width modulation (PWM). Significant amounts of computing time are required to compute local flux density variation considering such current harmonics. Since the amplitudes of higher harmonics are significantly smaller than that of fundamental harmonic, flux density variations due to the higher harmonics are small, and the relationship between the field strength and flux density can be assumed to be linear. When the operating point of each element is known, flux density variations for the higher harmonics can be analyzed by linear finite-element analysis (FEA). This paper suggests a method to calculate flux density variations in the iron core while taking into considering PWM current harmonics. First, the operating point solution is obtained by nonlinear FEA, second each element is linearized. Then, the flux density for the PWM current is obtained through linear FEA. Finally, the obtained results are presented and compared with nonlinear FEA results for verification.

In rotating motors, an electromagnetic analysis using finite-element analysis is performed according to the time interval such as the steps of the rotation angle. If the uncertainty of time variable is necessary to be handled, the time interval should become smaller than uncertainty values. It causes an increase of the cost even if the surrogate model is applied. Thus, space-time kriging surrogate model is proposed to consider time variable as well as space variable in the design stage. The proposed model handles time variable and predicts responses between time intervals to obtain outputs for the tiny uncertainty of time variable. The performance of prediction is verified with simulation data and then the reliability estimated by the proposed model is compared with measured data from manufactured prototypes.

This paper proposes a new numerical formula and a design method to reduce the torque ripple while improving efficiency and the control performance of an interior permanent magnet synchronous motor. In previous studies, the inverse cosine function (ICF) has been used for torque ripple reduction by making the air gap flux density distribution sinusoidal under a no-load condition. However, in this paper, the advanced inverse cosine function (AICF) based on the ICF is proposed. It determines an asymmetric rotor shape for rendering the air gap flux density distribution sinusoidal, considering a certain load condition. In addition to the torque ripple reduction, lower peak values, the total harmonic distortion (THD) of the induced voltage, and a lower iron loss can be achieved by applying the AICF, compared to the other conventional methods. The lower peak value and THD of the induced voltage are important because they affect the control performance of the motor. The lower iron loss can also lead to a higher efficiency, particularly, in the high-speed region. To verify the validity of the proposed design method, the characteristics of 8-pole, 12-slot motors that have different rotor shapes are analyzed using finite element analysis and experiments.

The aim of this study was to develop a stochastic model for predicting the bending strength distribution of glued-laminated timber (GLT). The developed model required the localized modulus of elasticity (MOE) and tensile strengths of laminae as input properties. The tensile strength was estimated using a regression model based on the localized MOEs and knot area ratios (KAR) which were experimentally measured for lamina grades samples. The localized MOE was obtained using a machine stress-rated grader, and the localized KAR was determined using an image-processing system. The bending strength distributions in four types of GLTs were simulated using the developed GLT beam model; these four types included: (1) GLT beams without finger joints; (2) GLT beams with finger joints; (3) GLT beams with different lamina sizes; and (4) GLT beams with different combinations of lamina grades. The simulated bending strength distributions were compared with actual test data of 2.4 and 4.8 m-long GLTs. The Kolmogorov–Smirnov goodness-of-fit tests showed that all of the simulated bending strength distributions agreed well with the test data. Especially, good agreement was shown in the fifth percentile point estimate of bending strength with the difference of approximately 1%.

Permanent magnet (PM) assisted claw-pole synchronous motor (CPSM) has commonly been used in a variety of industrial applications thanks to its robust structure and high energy density. However, such a motor has an axially asymmetric rotor configuration, which induces the corresponding 3-D magnetic field distribution. Thus, this paper proposes an infinitesimal hexahedron-element-based 3-D equivalent magnetic circuit network (EMCN) method in order to estimate the performance of the PM-assisted CPSM. The hexahedron element is considered an optimum unit element in describing the configuration of the PM-assisted CPSM in detail. That eventually makes it possible to evaluate the specific 3-D magnetic field distribution from which the flux linkage, the back-electromotive force, and the torque are also being calculated. The 3-D EMCN results are compared with 3-D finite element analysis (FEA) data and/or experimental data to validate their accuracy. Finally, it is proved that the scalar-potential-based 3-D EMCN method requires less computing time than the vector-potential-based 3-D FEA.