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This paper presents new results on a novel coupled-physics modality called magneto-acousto-electrical tomography (MAET). With static magnetic field, a beam of ultrasound is applied to the sample to be imaged; the ultrasonic vibration can lead to the separation of the charges due to the Lorentz force and produces the current distributed in the object. In this paper, simulations were conducted on biological tissue model, and the electrical properties were reconstructed, which could reflect the state of physiological or pathological. We also conducted experiments to detect the voltage signal of microvolt level by the electrodes placed around the sample. The series of experiments were conducted on low-conductivity (0.2 S/m) animal gelatin phantom and real biological tissue, successively placed in a 260 mT magnetic field and sonicated with a plane ultrasonic transducer of central frequency 2.25 MHz. In this paper, we obtained axis resolution of 1 mm, much more significant improvement than the previous reports. More importantly, the experimental result does also demonstrate the feasibility of MAET to image the electrical properties of biological tissue. [ABSTRACT FROM AUTHOR]

This paper is dedicated to study the experimental validation of a numerical model based on La-Fe-Co-Si layered operating near room temperature. For the purpose of this paper, a numerical simulation based on the transient energy equations is proposed for modeling the heat exchange between the multilayer material and the carrier fluid in the regenerator bed with an applied magnetic field of 1.5 T. The main findings of the simulation show a comparison between the numerical model and experimental setup including the magnetocaloric effect of La-Fe-Co-Si, pressure drop, and exergy and exergetic efficiency. [ABSTRACT FROM AUTHOR]

The high-voltage direct current cable insulations consist of polymeric or mass-impregnated paper materials. Their electric conductivities depend on the electric field and the temperature. Losses inside the conductor and in the insulation increase the temperature, resulting in increased losses and in a possible thermal runaway process. In this paper, coupled electro-thermal field simulations including nonlinear field-dependent conductivities are carried out. With a varying applied voltage and a current in the conductor, the condition for a thermal breakdown is computed. To compute the losses inside a 1-D insulation model, the finite-difference method is used. The simulation results conform well to experimental measurements. An approximation of the condition for a thermal breakdown is developed and show equal results in comparison to the coupled electro-thermal field simulations. [ABSTRACT FROM AUTHOR]

Through numerical simulations and calibrated experiments, the aim of the work presented in this paper is placed on the development of a polarity changeable magnetizing platform for a rotary magnetic encoder using a permanent magnet and thin silicon steel plate. Parameter studies are conducted via finite-element analyses to obtain optimized geometric design parameters for the magnetizer, leading to desirable magnetic flux density and effective magnetized patterns on the magnetic media. [ABSTRACT FROM AUTHOR]

Magnetic flux leakage (MFL) response predicting is important for defect estimation. This paper first proposes a concept of basic signal by discovering the combination property of the MFL response. The basic signal can be used to predict the MFL response conveniently by a basic signal combination method (BSCM), which is also innovatively put forward in this paper. In this method, the basic signal is calculated in advance, and the MFL response can be calculated by several transformation and combination operations. Both the simulation and experimental results demonstrate the feasibility of BSCM. Compared with other traditional methods (magnetic dipole method and finite-element method), BSCM shows a good performance on both the computational speed and accuracy. [ABSTRACT FROM AUTHOR]

Accurate modeling of soft- and hard-magnetic materials for the numerical simulation of rotating electrical machines is required to allow predictions on the operational characteristics along the torque–speed map, already in the design stage. The full potential of most appropriate material selection and concurrent geometry adaption can only be utilized if models can represent actual material behavior. The accurate prediction of iron losses of soft-magnetic materials for various frequencies and magnetic flux densities, as well as the degradation due to manufacturing is eminent for the design of electrical machines. Therefore, advanced material models need to be adapted and their accuracy examined to further improve the modeling and enable progression. This paper will give an overview of the current modeling approaches applied at the Institute of Electrical Machines for soft- and hard-magnetic materials in the simulation of rotating electrical machines. A case example in the form of a traction drive is presented to which the models are applied. For the machine modeling, the inhouse solver pyMOOSE is utilized. In order to determine the losses with regard to manufacturing processes, the iron-loss model with material degradation is used in combination with a machine simulation scheme of the entire operating range of the machine. Here, various simulation approaches are combined to form the entire computational toolchain to obtain accurate results in the entire operational range. [ABSTRACT FROM AUTHOR]

In magnetic recording systems, consecutive sections experience different signal-to-noise ratios (SNRs). To perform error correction over these systems, one approach is to use an individual block code for each section. However, the performance over a section affected by a lower SNR is weaker compared to the performance over a section affected by a higher SNR. Spatially-coupled (SC) codes are a family of graph-based codes with capacity approaching performance and low latency decoding. An SC code is constructed by partitioning an underlying block code to several component matrices, and coupling copies of the component matrices together. The contribution of this paper is threefold. First, we present a new partitioning technique to efficiently construct SC codes with column weights 4 and 6. Second, we present an SC code construction for channels with SNR variation. Our SC code construction provides local error correction for each section by means of the underlying codes that cover one section each, and simultaneously, an added level of error correction by means of coupling among the underlying codes. Third, we introduce a low-complexity interleaving scheme specific to SC codes that further improves their performance over channels with SNR variation. Our simulation results show that our SC codes outperform individual block codes by more than one and two orders of magnitudes in the error floor region compared to the block codes with and without regular interleaving, respectively. This improvement is more pronounced by increasing the memory and column weight. [ABSTRACT FROM AUTHOR]

Due to additive operation’s dominated computation and simplified network in binary convolutional neural network (BCNN), it is promising for Internet of Things scenarios which demand ultralow power consumption. By means of fully exploiting the in-memory computing advantages and low current consumption design using multilevel cell (MLC) spin-toque transfer magnetic random access memory (STT-MRAM), this paper proposes an MLC-STT-computing in-memory-based computing in-memory architecture to achieve convolutional operation for BCNN to further reduce the power consumption. Simulation results show that compared with the resistive random access memory (RRAM)- and spin orbit torque-STT-MRAM-based counterparts, the architecture proposed in this paper reduces power consumption by ~ $35{\times}$ and 59% in Modified National Institute of Standards and Technology data set, respectively. [ABSTRACT FROM AUTHOR]

Spatially coupled low-density parity-check (SC-LDPC) codes have emerged to possess capacity-approaching performance. The SC-LDPC codes can be decoded by a sliding window, therefore, the decoding latency and complexity of SC-LDPC codes are lower than those of underlying LDPC codes when the codeword length is very large. In this paper, the SC-LDPC decoder with the sliding window is employed in turbo equalization of magnetic recording systems. We examine the bit error rates (BERs) of the output of the sliding window during the iterative decoding, and then observe that the consecutive code blocks have approximately the same BERs. Herein, to reduce decoding complexity of SC-LDPC codes, the consecutive code blocks can be considered as the output of SC-LDPC codes. In addition, the non-uniform schedule update is adopted in the window decoding to avoid unnecessary updates within a window. The simulation results show that the proposed decoding algorithms applied in bit-patterned media magnetic recording systems can achieve a significant reduction in complexity compared to the traditional decoding without any loss in BER performance. [ABSTRACT FROM AUTHOR]

A method of getting the more accurate equivalent core length through 3-D electromagnetic finite element method (FEM) (3-D FEM) is presented in this paper. It is a matter of course that 2-D FEM is mostly used to evaluate the rotating machine performance instead of 3-D FEM. It takes 106 times longer to complete 3-D FEM than to complete 2-D FEM according to the simulation data in this paper. The motor has the radial air-cooling ducts in the stator. The use of radial air-cooling ducts has an effect on the electrical performance of its machine due to the fringing effect between ducts. The way to consider that effect is that the actual core length has to be replaced with the equivalent core length to reflect the magnetic circuit of 2-D perspective. However, there is 12% error of the root mean square no-load voltage between 2-D and 3-D FEM in 16 MVA salient pole synchronous motor. The cause of the error is the miscalculated equivalent core length in 2-D FEM. The purpose of this paper is to study the cause of the error through 3-D FEM to get the more accurate equivalent core length in 2-D FEM. Finally, Generator open circuit characteristic test is also carried out to verify the no-load voltage of 2-D and 3-D FEM. [ABSTRACT FROM AUTHOR]

How animals navigate in their cross-continental migration has puzzled scientists for centuries. To date, the mechanism behind this mysterious navigation remains unclear. In this paper, a hypothesis is developed and computer simulations have been performed to investigate long-distance animal navigation. Simulation results show that animals may be able to complete their long-distance navigation by observing a spatial angle included by the geomagnetic field line and a geographic direction, without necessarily knowing any prior landmark information. Our results not only match existing observation reports in detail on the long-distance migration routes of animals, but also are able to explain the conflicting evidence on the role of geomagnetic field in animal navigation. We think our results could help reveal the actual mechanism of animal navigation. This paper also provides a potential solution for global and local area navigation of mankind and machines assisted by artificial sensors. [ABSTRACT FROM AUTHOR]

In the design of high-temperature superconductor (HTS)-based electromagnetic devices, some of the major challenges include ac loss reduction, minimization of heat leakage, and reduction of the amount of HTS material used to decrease costs. This paper considers a computer model of HTS-based leads involving a multiphysics scenario that considers the electromagnetic and thermal behavior of the system. This paper attempts to address the requirements mentioned and provides an optimum solution by applying an approach based on multiobjective optimization. The differential evolution technique, a stochastic method, widely known for the ease of use and its ability to handle adequately non-differentiable, non-linear, and multimodal cost functions was used. The proposed framework provides a technique to optimize effectively HTS leads, which not only deals with the non-linear aspect of HTS materials, but also includes a multiphysics environment. [ABSTRACT FROM AUTHOR]

Computer simulations of the magnetizing process have been carried out by applying a numerical model to the theory of magnetization and demagnetization for magnetic materials. The numerical model (written using the Python programming language) is able to calculate the magnetization/demagnetization of the permanent magnet material according to its $B$ – H$ curves. This numerical model is combined with an existing finite-element method (FEM) model in which the result of computations is the approximated potential value in the FEM mesh. The aim of this paper was to develop a tool able to simulate the behavior of an anisotropic sintered permanent magnet during the demagnetization process. The permanent magnet material that has been studied in this paper is sintered Nd–Fe–B and it was modeled taking into account an average misalignment angle related to the magnet easy axis. This model also takes into account different demagnetizing field directions, such as a demagnetizing field perpendicular to the orientation direction, which is often ignored. It is shown that even a demagnetizing field perpendicular to the magnetization direction can produce visible demagnetization effects. A Gaussian distribution of the average misalignment angle in the permanent magnet material is also taken into account as well as its variation. Demag curves have been calculated varying the misalignment angle and the intensity and direction of the external magnetic field. The simulation results are in perfect agreement with the {1}/{\cos \theta} law. The model can be applied in many magnetization and magnetic tuning applications. [ABSTRACT FROM PUBLISHER]

This paper presents the reduction of noise and vibration concerning the magnetostriction effects for a single-phase power transformer with a large capacity of 200 MVA. Two magnetic core shapes are investigated: 1) D-yoked core and 2) square-yoked core. The D-yoked core is used for the construction of the transformer prototype in this paper. The magnetostriction and the hysteresis loop of the core material are measured for the simulation and analysis of noise and vibration. The transformer prototype is assembled with an external clamping force applied on the core, and the core vibration and sound-level are observed. The transformer operates with a periodic excitation that may induce resonance in the core. To avoid this, a finite-element analysis is used for modal analysis to identify the natural frequencies of the core. A tank is also designed with a sufficiently rigid structure to avoid resonances. The sound-level of the fully assembled transformer prototype is measured, and it is found to have a low-noise level below 65 dB. [ABSTRACT FROM AUTHOR]

Magnetically mediated thermoacoustic imaging (MM-TAI) is an emerging medical electrical parameter imaging technology; it has the advantages of high contrast of electrical impedance imaging and high resolution of ultrasound imaging; it can realize the early diagnosis of disease in the tissues comparing with structure imaging technology. The magnetically mediated thermoacoustic (TA) effect is analyzed in this paper through the theoretical inference, numerical calculation, and experiment. Pulsed excitation is considered in the analysis, which is different from previously reported research. The pulsed magnetic field is applied to the low conductivity sample such as gel phantoms (0.2, 4, and 2.5 S/m); then the Joule heat is generated inside the objects and an acoustic signal is excited due to heat expansion. The acoustic signal is detected and the image is reconstructed from TA source to conductivity. This paper has laid the foundation for the MM-TAI in biological tissues. [ABSTRACT FROM AUTHOR]

This paper analyzes the incline unbalanced magnetic pull (IUMP) generated in the permanent magnetic synchronous motor (PMSM) with the rotor misalignment. The motor magnetic field in such a motor is asymmetric, and both the magnitude and the action point of UMP vary in motor operation. This paper presents an analytical model for analyzing the 3-D effects of the UMP induced by the misalignment rotor. The numerical simulation results prove the effectiveness of the proposed analytic model. [ABSTRACT FROM PUBLISHER]

In case of an aortic dissection (AD), the aortic shape as well as the blood flow will be altered in the region concerned. Based on the thoracic electrical bioimpedance technique that allows to identify and quantify conductivity changes by measuring the impedance on the thorax, a numerical simulation model for investigating effects caused by ADs is proposed. In order to find a simple non-invasive method for the detection of ADs, the possibilities and limits of applying a bioimpedance technique are shown in this paper. [ABSTRACT FROM AUTHOR]

To study how the fat affects the quantification of magnetic susceptibility of iron oxide nanoparticles (IONPs) according to the chemical shift effects, especially at ultra-short echo times, simulation experiments were carried out in this paper. Numerical phantom of IONPs solutions with six different concentrations was designed. Magnetic resonance imaging signals with different fat fractions (ffs) were generated according to a multi-peak chemical shift model. Quantitative susceptibility mapping (QSM) was calculated, and the relationship between the QSM value and ff, as well as echo selection, is evaluated. The results show that streaking artifacts become more and more severe when ff increases, which makes QSM value overestimated. Shortened echo spacing time can reduce streaking artifacts with the same ff. These findings will benefit future clinical evaluations for quantification of iron in vivo. [ABSTRACT FROM AUTHOR]

In this paper, each component of the no-load loss of interior permanent magnet motors under the conditions of both sinusoidal supply and converter supply is investigated by the finite-element method and experimental method. The no-load loss is calculated at different rotation speeds, two different slot and pole combinations and different converter parameters. The wireless temperature sensor embedded in the interior rotor is used to test the temperature of the permanent magnet under no-load condition, and the permanent magnet loss is calculated according to the slope of the initial temperature–time curve. Then, the mechanical loss of the prototype is measured by dragging a nonmagnetic rotor. The total tested losses are subtracted from the copper loss, the mechanical loss, and the permanent magnet loss to obtain the test results of core loss, and the experimental results of each loss and permanent magnet temperature rise are compared with the corresponding calculated results to verify the correctness of the simulation results. [ABSTRACT FROM AUTHOR]

Magnetic gears with dual-mechanical port have several attractive features, such as reduced maintenance requirements and inherent overload protection, as compared with mechanical gears. However, it is difficult to obtain an intuitive analytical model because of its complicated magnetic flux interaction, and the dual-port transmission of this magnetic gear is rarely discussed. These difficulties actually limit the practical applications and increase the control difficulty. Therefore, this paper develops a modeling approach based on the block diagram. Both of the kinematic and dynamic characteristics for a dual-port transmission can be obtained in one unified description. This control-based approach also provides more flexibility and convenience, facilitating further control applications. The feasibility will be verified by finite element analysis simulation and experimental results. [ABSTRACT FROM AUTHOR]

The magnetic flux leakage (MFL) type pipeline inspection gauge (PIG) is commonly used to detect defects on the underground pipelines as one of the nondestructive testing instruments. Although it is effective for the inter-city scale large size pipeline, it is hard to detect defects for the small size pipeline installed inside the city. So, it is necessary to adopt self-driving robot system to drive PIG module because the small gas pressure inside a small size pipeline is not enough to push PIG module. Even though it is enough to pass in straight line, when this module passes through bent pipe or welded pipe joint, the magnetic force between pipe and inspection module is increased sharply so that the PIG module could be stuck eventually. This paper proposed a new design structure of MFL system to decrease stuck forces on the pipe wall. All structural parameters for MFL sensors based on the magnetic field theory were designed to minimize the magnetic force and maximize the detection sensitivity of defect signals. The performance of the proposed system was verified by simulation results using 3-D finite-element method and experimental measured ones. [ABSTRACT FROM AUTHOR]

This paper presents an evaluation of the EMFs in the human body exposed to the wireless inductive charging system of electric vehicles such that the compliance of this charging system with respect to human EM exposure limits can be examined. A magnetic resonance imaging-derived and high-resolution model of the human body is used. An exposure assessment of a representative wireless inductive charging system, under a limited set of operating conditions, is provided to estimate the induced EMFs. The numerical analysis is performed with the finite element method. Numerical modeling of the system next to a standing human model shows that the EM exposure limits can be absolutely satisfied even when the transmitter coil is very close to the body. Furthermore, the worst configuration for the exposure evaluation of the wireless charging system is taken into consideration. This paper provides a useful guideline for the industry to develop inductive charging systems following the safety standards of radiation protection. [ABSTRACT FROM AUTHOR]

One of the main engineering applications of ferrofluids is in magnetic fluid seals, working in rotary motion. An area, which has so far been insufficiently examined, is the mechanism of leaks between seal stages in this type of seal. This is an important issue in order to understand the principle of the seal operation and to properly design this type of seal. This paper presents the results of research into the mechanism of leaks between stages in multi-stage magnetic fluid seals. The tests were conducted when the pressure of the sealing air increased and reached its maximum value. The influence of the magnetic fluid properties, such as saturation magnetization or dynamic viscosity, was taken into account. Studies were performed for different seal temperatures. Experiments allowed models for determining the maximum pressure of the multi-stage seal to be proposed, based on the information about this pressure for a one-stage seal. This paper presents the comparative results of the critical pressure value obtained from experimental studies and calculations based on numerical simulations. [ABSTRACT FROM PUBLISHER]

Ferromagnetic granules show a complex behavior under a magnetic field. This phenomenon is observed in the forming process of bonded magnets, ferrofluid, magneto-rheological fluid, and magnetic brush image development. However, it is difficult to model the ferromagnetic granules. This paper proposes a numerical simulation method for the ferromagnetic granules. In this method, the discrete element method and method of moments are coupled. The proposed method is applied to simulate the behavior of the ferromagnetic granules under static magnetic field. [ABSTRACT FROM AUTHOR]

Two-dimensional magnetic recording (TDMR), which combines shingled magnetic recording (SMR) with 2-D signal processing attracts attention from the hard disk drive industry. SMR is a magnetic recording system in order to increase the track density by writing tracks without the guard band. Therefore, the influences of writing and reading intertrack interferences (ITIs) deteriorate the quality of reproducing waveforms. Additionally, degradation of track due to overwriting and crosstalk from the adjacent tracks due to the width of reader sensitivity. The equalization using 2-D finite impulse response filter for the waveforms from three adjacent tracks is proposed as a method to reduce the influence of reading ITIs. In this paper, we evaluate the bit aspect ratio (BAR) in TDMR read/write channel under a specification of 4 Tb/in2 using bit error rate of the low-density parity-check (LDPC) coding and iterative decoding system obtained by computer simulation. The results show that the suitable BAR in array head reading is 2.0. [ABSTRACT FROM AUTHOR]

Magnetic-valve controllable reactor (MCR) has been widely applied in many kinds of industries, such as power systems and ferrous metallurgy. As electrical equipment, MCR can adjust its reactance smoothly and continuously, which has advantages like low dissipation and maintenance costs, high reliability. In this paper, a precise 2-D field-circuit coupling model of MCR is established by the finite element analysis software-ANSYS, and then the analysis of the harmonic characteristics of this model is presented in detail. Compared with the conventional numeric method, the proposed method could obtain more practical and accurate results and also has the ability to analyze electromagnetic field. Meanwhile, an experimental platform of a 2200 VA/380 V MCR is built. This paper provides detailed harmonic characteristics analysis of simulation and experiment. The simulation and experimental results verify that the proposed method is more accurate than using conventional ways. [ABSTRACT FROM PUBLISHER]

High-temperature superconducting quantum interference devices (HTS SQUIDs) have been developed as an extremely sensitive magnetic sensor. The HTS SQUIDs are required to have high robustness with respect to the magnetic noise for stable operation in an unshielded environment and also reduced cost to widen the application range. It is, therefore, necessary to clarify the quantum magnetic behavior of the HTS SQUID. However, a simulation tool, which can consider the quantum magnetic behavior, has not been developed yet. In this paper, an equivalent circuit of a Josephson junction comprising the HTS SQUID is more properly considered to represent the quantum behavior. It can consider the ac and dc Josephson effect. The obtained results are compared with an ordinary simulation using a simplified circuit model, and the results agree well with each other. Using the proposed simulation method instead of the ordinary simulation, the current path is more accurately simulated, so this new method will be used to evaluate the robustness of the SQUID. [ABSTRACT FROM PUBLISHER]

Magnetic particles have become a core ingredient for many applications in chemistry, biology, and medical diagnostics, e.g., as basis for bioanalytical methods or tracer material for medical imaging. This paper discusses the theory and presents numerical simulations of a new method called rotational drift spectroscopy (RDS), which uses rotating magnetic fields for measuring the properties of magnetic nanoparticles (MNPs) in liquid suspensions. The RDS signal is based on the nonlinear rotational drift behavior of MNPs in rotating magnetic fields, which is highly dependent on the properties of the MNPs as well as their interaction with the environment. This dependence makes it a highly promising tool for detecting the binding of functionalized MNPs with, e.g., proteins, viruses, or cells. This paper presents the theory and numerical simulations of this method. [ABSTRACT FROM AUTHOR]

The equivalent electric circuit of an electrical machine is a powerful tool for analysis and it can also be very helpful in the design stage. In this paper, we present the work carried out to obtain the equivalent circuit of an electromagnetic pump, which consist of two other machines series connected. Each of these machines, a transformer-type one and an electromagnet, are affected by the magnetic field created by the other. This means that the simpler equivalent circuit formed by joining the well-known equivalent circuits of each machine is not valid. To understand the discrepancy between this simpler equivalent circuit and the real behavior of the electromagnetic pump, numerical simulation and experimental validation were used. As a result, a new equivalent circuit is proposed that considers an inductive coupling that exists between both machines. [ABSTRACT FROM AUTHOR]

From June 29 to July 2, 2015, McGill University in Montreal, Canada, was the host of the 20th edition of the International Conference on the Computation of Electromagnetic Fields (Compumag 2015). Every two years since its inception in Oxford, U.K., in 1976, Compumag has provided a forum for the international computational electromagnetics community to come together and exchange ideas and develop new research areas. Over its history, we have seen the computation of electromagnetic fields advance from extremely simple systems in the early days of finite elements and integral methods to the advanced systems of today capable of dealing with 3-D systems handling eddy currents, nonlinearity, and motion on a laptop computer. Simulation has clearly come of age in our area. [ABSTRACT FROM AUTHOR]

The key components in wireless power transmission for the wireless recharging of electric vehicles are the pair made by the external power line and the on-board pickup module. This paper analyzes a charge while driving system by using a lumped parameter extraction with the partial element equivalent circuit method and a circuit simulation. [ABSTRACT FROM AUTHOR]

Due to their specific position and role in electric power systems, generator circuit breakers (GCBs) must be so developed and manufactured that they can withstand extremely high short circuit currents several times over their entire lifetime. Therefore, an accurate and efficient method for performing a coupled electromagnetic-mechanical simulation of a GCB in its full geometrical complexity is of paramount importance for daily design. This paper presents in detail a novel method for coupling of electromagnetic and dynamic mechanical analysis for GCBs. The suggested method is fast, accurate, efficient, robust, and suitable for 3-D geometries of high complexity. [ABSTRACT FROM AUTHOR]

The large normal force of the permanent magnet linear synchronous motor (PMLSM) is caused by the PM group shifting. This is the significant drawback which will deteriorate the performance of the drive system in high-precision applications. In the optimization design process, when the PM group shifting length is not zero the normal force will be changed into a pulsation curve with large amplitude. To solve this problem, this paper proposes that the PMLSM is divided into two symmetrical PMLSMs. The effectiveness of this proposed structure is verified by the simulation and experiment according to the comparison of the electromagnetic force characteristics between the conventional and proposed structures. [ABSTRACT FROM PUBLISHER]

Recently, the permanent magnet-assisted synchronous reluctance motor (PMa-SynRM) that can replace induction motor has been more studying because of the needs of the high efficiency motor development for minimum energy performance standard. PMa-SynRM requires the speed and position information of rotor to control motor correctly. However, sensor for rotor information has many problems such as mounting space shortage and the additional system cost. Therefore, in this paper, the speed-sensorless control based on reference model adaptive control is introduced to eliminate the sensor. And mechanical design is improved for control. The proposed method is verified by simulation. [ABSTRACT FROM AUTHOR]

In this paper, we investigate a magnetic tunneling junction (MTJ) device as a stochastic quantizer. Thermal noise in an MTJ is one of the parameters in determining its output, 0 or 1. This thermal noise, which causes random switching in a magnet, can be successfully exploited to implement high-performance stochastic quantization on an analog input (the function relating MTJ’s output state to its analog input is defined as an MTJ quantization function). Subsequently, an optimized signal-to-noise ratio (SNR) is found to maximize the information throughput. The best output to input correlation is achieved when the input signal’s amplitude is 1.5 times the standard deviation of the MTJ’s quantization function. We also demonstrate that an MTJ-based quantizer offers the highest performance when the information to be quantized is normally distributed in the input signal. Simulations to quantize images containing information, such as light intensity and pattern, also confirmed the highest information throughput when this optimum SNR is utilized. [ABSTRACT FROM AUTHOR]

With the development of science technology, ferrofluid seal has been intensively applied in mechanical industry, but more and more larger sealing stages are needed. At present, the literature mostly concentrated on numerical analysis with few pole pieces ferrofluid seals and focused on the critical pressure value in one-stage magnetic fluid seal, lacking of numerical simulation and experimental validation on the static pressure of multi-stage ferrofluid seals. On this basis, the analysis of larger number of sealing stages is presented. And numerical simulation along with experiment investigation was used to study the seal capacity of ferrofluids in different seal gaps and different seal stages in this paper. The results show that the theoretical value is well coincident with experimental value when the sealing gap is less than 0.2 mm. Increase the number of the pole tooth can significantly improve the seal capacity of ferrofluid seal, but the sealing pressure of ferrofluids does not increase linearly with the addition of the number of pole teeth. For the new structure, the pressure of one-stage pole tooth has more than doubled as the sealing clearance is 0.2 mm and 3.5 times increase when the sealing gap is 0.3 mm. [ABSTRACT FROM AUTHOR]

The magnetic fluid seal is one of the best known and widely used technical applications of magnetic fluid. However, the boundary and the flow regime with the rotation shaft cannot be observed by the experiment method. This paper presents a novel numerical simulation method to obtain the boundary and the velocity of the fluid in seals. The magnetic field of the seal is solved by the finite-element method, and the Navier–Stokes equations of the magnetic fluid based on the influence of magnetic force are solved by the finite-volume method. The two-phase flow is solved by the volume of fluid method. The seal capacities of the rectangle tooth and the trapezoid tooth with different rotation velocities are obtained. The result shows that the seal capacity decreases with the increase in the rotation velocity. [ABSTRACT FROM AUTHOR]

To achieve high-speed scanning of defect detection, this paper proposes a motion-induced eddy current (MIEC) thermography method, which utilizes the relative movement between permanent magnet array and the inspected object to induce the eddy current. Specifically, a set of circumferentially arranged permanent magnets rotating in a steel pipe is used to implement the proposed method. Numerical simulation and experimental studies are conducted to investigate the MIEC and thermal distribution influenced by speed, crack orientation, and lift-off effects. The results show that thermal contrast of the crack rises with its orientation to MIEC flowing path changing from parallel to perpendicular; thermal contrast decreases sharply with the lift-off distance of the magnet array increasing. One merit of the proposed MIEC thermography is that MIEC intensity (thermal contrast) increases with scanning speed and benefits the defect detection. [ABSTRACT FROM AUTHOR]

Radio frequency (RF) coils are an important component of magnetic resonance imaging (MRI) equipment. However, the field of ultrahigh-field RF coil research is fraught with technical challenges which limit the development of magnetic resonance technology. Thus, the research on the performance of ultrahigh magnetic field RF coils is a primary focus on the study of the ultrahigh-field MRI system. The development of 1H/31P dual-nuclear RF coils based on the ultrahigh-field MRI system is greatly significant for the research on the diagnosis and metabolism changes of many disease conditions such as tumors. In this paper, a 1H/31P dual-nuclear multi-channel RF coil for the ultrahigh magnetic field 7 T MRI was proposed. The performance of the proposed coil was evaluated by using a numerical co-simulation approach, and phantom studies were conducted on the Siemens 7 T MRI system. The results demonstrate the feasibility of the proposed double-nuclear RF coil in the application of 1H/31P ultrahigh magnetic field MRI. [ABSTRACT FROM AUTHOR]

This paper proposes and analyzes the design philosophies of the single-phase main exciter (ME) for an aircraft wound-rotor synchronous machine and investigates its operating characteristics in both generating and starting modes. The fundamental structure and starting–generating system are discussed. The load features of single-phase ME are summarized. The ME has the characteristics of linear current amplifier and approximately constant current source the generating mode, which can be used in the wide range of working temperature. Detailed waveforms and finite-element analysis verify that excitation current $I_{\mathrm {ef}}$ is almost irrelevant to speed but in direct proportion to frequency in the starting mode. Besides, simulated data indicate that the energy transferring efficiency between ME stator and rotor can reach about 55% by the single-phase ac excitation method. Finally, the experimental verification is carried out, and the simulated and experimental data and waveforms of single-phase ME agree well with each other. [ABSTRACT FROM AUTHOR]

This paper proposes and implements a switched-capacitorless energy-encrypted transmitter and a 2-D frequency and duration encryption (FDE) technology for roadway-charging electric vehicles based on wireless power transfer (WPT). To prevent the encrypted energy package from being illegally decrypted by unauthorized receivers, the proposed 2-D chaotic FDE scheme generates a well-defended security key to improve the security performance for the multi-receiver WPT system. Moreover, by introducing a continuously energy-encrypted transmitter without using a switched-capacitor array as well as a hybrid modulation of pulse density modulation and pulse frequency modulation, the proposed FDE-WPT system can offer high energy security while maintaining high efficiency at flexible operating frequencies. Theoretical analysis, computer simulation, and experimental results are provided to verify the feasibility of the proposed FDE-WPT system. [ABSTRACT FROM AUTHOR]

Electromagnetic (EM) coupling between radio frequency (RF) coils is a common cause of coil performance degradation and must be sufficiently reduced in the design of RF coils. The EM field simulation is a primary tool in analyzing the coupling condition and optimizing the decoupling method. A theoretical analysis of co-simulation under the conditions of strongly coupled RF coils is proposed in this paper. The proposed co-simulation method is evaluated through the comparison with the conventional simulation methods in terms of the efficiency and of the EM fields and specific absorption rate (SAR) of a two-channel strongly coupled coil array. The results demonstrate that the proposed co-simulation method saves approximately 94.5% of the total simulation time for strongly coupled coil arrays while the EM field and SAR variation is less than 4%. As a method demonstration, the proposed co-simulation method was used to analyze the capacitance decoupling of adjacent coils with the scattering matrix and saves about 95.78% of the total simulation time for the optimization of decoupling capacitors. [ABSTRACT FROM AUTHOR]

High-power rating three-phase squirrel cage induction motors (SCIMs) may be equipped with sleeve bearings (SBs). Oil-whirl fault (OWF) is an important fault mode of the SBs, which can lead to their serious damage. On-line condition monitoring is recommended to detect possible incipient OWFs in the SBs before total failure of them and catastrophic stop of the machine. The OWF usually happens only in one of the motor SBs and introduces time-variant mixed radial–axial asymmetry to the air gap distribution. To study the SCIM performance under the OWF in one of its SBs, this paper proposes an analytical modeling and simulation approach. Multiple coupled circuit modeling along with the 2-D modified winding function theory is used for this purpose. The modeling and simulation results show novel harmonic components in the stator line currents, as well as the self-inductances of the stator windings due to the fault. The latter harmonics can be used as indices for diagnosing the bearing OWFs as well. Regarding the sensitivity to the fault severity and robustness against the load level change and the mains voltage unbalance degree change, simulation-based studies are used to determine the most appropriate inductance harmonic as the OWF index. [ABSTRACT FROM AUTHOR]

The 2-D magnetic recording (TDMR) by shingled magnetic recording (SMR) draws attention as a technology to increase the recording densities in a hard disk drive. The magnetization pattern is curved by the write field at the corner of the writer in SMR, and the information to read/write (R/W) channel performance is feared. Therefore, it is possible that the bit error rate performance is improved by fitting the reader sensitivity to the bit shape. In this paper, we evaluate the effect of reader sensitivity rotation in the TDMR R/W channel with head skew under a specification of 4 Tb/in2 by computer simulation, applying the low-density parity-check coding and the iterative decoding system with the 2-D finite impulse response filter. The results show that the rotated reader sensitivity fits the recorded bit magnetization shape, and the error-free skew range increases to -3^\circ \sim 6^\circ . Therefore, the reader sensitivity rotation is considered to be an effective way to improve the skew margin in the TDMR system. [ABSTRACT FROM PUBLISHER]

Heat-assisted magnetic recording (HAMR) is a promising approach to increase the areal density of hard disk drives. The purpose of this paper is to provide a computational framework for optimizing the HAMR system. In order to do that, an integrated HAMR simulation system was built. We then studied several factors that could affect the playback signal-to-noise ratio (SNR), such as the switching time of the writing field, the peak temperature of the heat spot, the standard deviation of anisotropy field and exchange parameters, and the size of the reader element. We found that bit length (BL) becomes the key factor for the value of SNR for small, e.g., 10 nm, BLs. We established a relationship between the SNR and the bit error rate so that it will be easy to predict the storage capacity based on the playback SNR. This curve is used to predict the possible storage capacity for different BLs. [ABSTRACT FROM AUTHOR]

In this paper, a variable-speed operating doubly salient electromagnetic generator (DSEG) for an automobile power system is proposed and investigated. Analysis and comparison between the 12/8-pole and the 18/12-pole configurations are given. The 18/12-pole DSEG is more suitable for the wide-speed range operation in terms of the capability of output power and efficiency due to the smaller reactance. The characteristic of flux regulation for the constant power operation in a wide speed range is analyzed, and the corresponding loss variation and efficiency is obtained as well. Finally, a prototype 18/12-pole DSEG has been designed. Both the simulation and the experimental results indicate that the proposed DSEG can offer a more desirable and stable power performance over a wide speed range with simple control for the automobile on-board generation application. [ABSTRACT FROM AUTHOR]

A novel mechanical device applied in an axial field variable flux permanent magnet synchronous machine (AFVFPMSM) is proposed in this paper, of which the structure of AFVFPMSM and mechanical device is given in detail. The operation principle of AFVFPMSM is analyzed and its flux weakening capability is studied based on mechanical dynamic simulation and finite-element analysis (FEA). Some electromagnetic characteristics including flux linkage, electromotive force, and inductions are calculated by 3-D FEA. The analysis results show that a good flux weakening ability for AFVFPMSM is obtained using the novel mechanical device. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to present an asymmetrical V-shape rotor configuration of an interior permanent magnet (IPM) machine for improving the torque characteristics, i.e., reducing cogging torque and torque ripple. Using this rotor configuration, the great reduction of the cogging torque and the torque ripple can be achieved. To acquire more desired torque characteristics, an optimization design is implemented using hybrid genetic algorithm-Taguchi (HGAT). Time-stepping finite-element analysis is adopted to calculate the torque characteristics for comparison and analyses. The best set of design parameters is found out; and the IPM model optimized using the HGAT shows even better torque characteristics. An IPM machine prototype having HGAT-design parameters was manufactured for test, and the effectiveness of the proposed rotor is verified by comparison between the simulation and the experiment results. [ABSTRACT FROM AUTHOR]

In this paper, an efficient and effective magnetic circuit model is developed for the analysis of a magnetless double-rotor flux switching motor. First, a magnetic circuit network for the proposed machine is built, and formulas for the calculation of the magnetic components in the circuit, including the permeances of teeth, yokes, slots, leakage permeances, and air-gap permeances, are derived. Then, by applying Kirchhoff’s current law to each node in the network, nodal analysis is used to solve the matrix equation. All the circuit variables, and hence the complete motor magnetic characteristics are being considered. When the rotor rotates, the air-gap permeances are adjusted accordingly, and the above calculations are repeated, so as to find the complete static performance of the motor. Last, the validity and the effectiveness of the proposed method are verified using both the experimental results and the simulation results obtained from the time-stepping finite-element method. [ABSTRACT FROM AUTHOR]