International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Nick, A.S. | Vynnycky, M. | Jönsson, P.G.

Article Type: Research Article

Abstract: A recent three-dimensional (3D) model that revisited earlier theoretical work for longitudinal electromagnetic stirring in the continuous casting of steel blooms is analyzed further to explore how the bloom width interacts with the pole pitch of the stirrer to affect the magnetic flux density. Whereas the first work indicated the presence of a boundary layer in the steel near the interface with the stirrer, with all three components of the magnetic flux density vector being coupled to each other, in the analysis presented here we find that the component along the direction of the travelling wave decouples from those in …the other two directions and can even be determined analytically in the form of a series solution. Moreover, it is found that the remaining two components can be found via a two-dimensional computation, but that it is not possible in general to determine these components without taking into account the surrounding air. The validity of the asymptotically reduced model solution is confirmed by comparing it with the results of 3D numerical computations. Moreover, the asymptotic approach provides a way to compute the time-averaged Lorentz force components that requires two orders of magnitude less computational time than the fully 3D approach. Show more

DOI: 10.3233/JAE-200010

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-27, 2020

Authors: Ma, Yuan | Feng, Wen | Yan, Zhen

Article Type: Research Article

Abstract: The buckling analyses of type-II superconducting strip under applied perpendicular magnetic field and/or distributed uniform mechanical load are investigated in this paper. Based on the Bean critical state model, the electromagnetic body force is firstly given. Then, based on the classical plate theory and two-point initial value method, the critical buckling states of the superconducting strip with different boundary conditions are analyzed. Numerical results show the effects of both the thickness and boundary conditions of superconducting strip on the corresponding critical buckling loads. The present work should be helpful to the research and application of superconducting thin strips.

Keywords: Superconducting thin strip, electromagnetic body force, buckling, critical buckling load

DOI: 10.3233/JAE-190115

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2020

Authors: Zhang, Yuanyuan | Meng, Fanhui | Liu, Zhao | Xing, Manman | Pang, Huaji | Deng, Meng

Article Type: Research Article

Abstract: A satellite remote imaging data is used to describe the actual ground surface around east of Shandong, based on Barrick’s formulations and Wait’s formulations, and considering the time errors due to elongation of the propagation path caused by mountains, this paper comprehensively analyzes the lightning vertical electric field over the actual ground surface. Furthermore, its effects on time-of-arrival (ToA)-based lighting location systems (LLS) are discussed in details and results show that wave-shape and time-delay of the electromagnetic fields can be significantly affected when they propagate over actual ground surface. The time-delay of the field waveform becomes longer with the increasing …roughness, but subtle effect on field peak. After analyzing the actual ground surface around district of Qingdao, this paper reveals the relation between azimuth, observation distance and time-delay. The location error caused by actual ground surface is about several kilometers around the district of Qingdao, and the revised stroke points which are evaluated by the improved actual ground surface propagation model are closer to the actual lightning strike points. Show more

Keywords: Digital elevation model (DEM), lightning vertical electric fields, actual ground surface propagation model

DOI: 10.3233/JAE-201506

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2020

Authors: Chen, Jun-Wei | Liu, Xing

Article Type: Research Article

Abstract: In this paper, the winding inductances of a linear ironless permanent-magnet synchronous actuator for high-precision applications is discussed. Different from rotary motors for conventional applications, high-order harmonics and the end effect due to discontinuous structure are considered. From such considerations, an improved Fourier series expansion is applied to the proposed distributed-parameter model of the linear winding. The calculated inductance matrix is of high accuracy, and presents a new non-uniform form. New features of the inductance matrix are analyzed, and the decoupling scheme is implemented via variable transformation and real-time updating inductances.

Keywords: Winding inductance, linear PM actuator, Fourier series expansion, end effect

DOI: 10.3233/JAE-201571

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-16, 2020

Authors: Guo, Huan | Su, Sanqing | Wang, Wei | Ma, Xiaoping | Yi, Shuchun | Zhao, Xuran

Article Type: Research Article

Abstract: Metal magnetic memory (MMM) testing is a nondestructive approach for evaluating the stress concentration and early damage of ferromagnetic components. However, research on the MMM testing of large steel structures has been limited. Thus, this study investigates the suitability of MMM technology for monitoring the damage in steel structures exposed to complex stresses. The normal components of magnetic signals H p (y ) on the beams and columns of a portal frame are obtained through pseudo-static testing. The signal increment ΔH p (y ) and its absolute value |ΔH p (y )| under different loads are …analyzed. The relationship between the equivalent stress and magnetic signal is investigated through numerical simulation. The results show that the ΔH p (y ) curves are similar during the elastic stage but change abruptly during the plastic phase. Moreover, the differences in the magnetic signal directions caused by the varying detection directions cannot be ignored. In the elastic stage, with the increase in the load, |ΔH p (y )| curves initially increase and then decrease. The formation of the ΔH p (y ) curve is similar to the distribution of the equivalent stress. The mutation of ΔH p (y ) can determine whether a specimen is entering the plastic phase, and can warn against structural failure. The magnetic signal distribution qualitatively reflects the stress distribution. Show more

Keywords: Metal magnetic memory testing, monitoring damage, normal magnetic signals, pseudo-static test, portal frame, equivalent stress

DOI: 10.3233/JAE-190135

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2020

Authors: Li, Jiahao | Yang, Guolai | Fan, Yumeng

Article Type: Research Article

Abstract: This paper provides an analytical method for calculating the electromagnetic field of the tubular linear permanent magnet eddy current brake. The method of separating variables based on Fourier series is used to solve the boundary value problem, and the analytical solution of electromagnetic field is obtained. The braking force is obtained by calculating the Lorentz force. Then the accuracy of the analytical method is verified by comparing the analytical solutions with the solutions obtained by finite element method (FEM). In order to improve braking performance in a limited space, the parameter analysis is carried out to investigate the influence of …various structural parameters on the braking characteristics. According to the results of parameter analysis, the range of design parameters is determined. Finally, a multi-objective optimization is applied to find the optimal design parameters of the eddy current brake. The braking force increases by 27% and the volume of permanent magnet decreases by 7.7% after optimization. Show more

Keywords: Eddy current brake, braking force, finite element method, genetic algorithm, Halbach array

DOI: 10.3233/JAE-201523

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-23, 2020

Authors: Li, Zixuan | Yang, Guolai | Wang, Liqun

Article Type: Research Article

Abstract: This paper investigates the damping and demagnetization effect of an electromagnetic buffer (EMB) under impact load. The motional eddy currents are calculated first, and the Ampere circuital theorem is employed to calculate the induced magnetic field. The demagnetization effect is formulated by the magnetic Reynolds number with a correction coefficient k m . Following this, the time-step finite element (FE) model of the buffering system is constructed based on the nonlinear B–H curve. The accuracy and feasibility of the FE model is preliminarily verified by small-scale impact test. The characteristics of damping displacement, velocity, damping force and damping coefficient are …obtained. Then, the demagnetization effect is analysed by eddy current, magnetic field distribution, through the intensive impact load test at room temperature and time-step FE model. The value of k m is obtained through the intensive impact test and the simplified expression of critical velocity. The results show that the demagnetization effect is obvious with the increase of velocity. By introducing the correction coefficient of magnetic Reynolds number, the eddy current demagnetization process is more realistic. Show more

Keywords: EMB, intensive impact load, demagnetization, magnetic Reynolds number, critical velocity

DOI: 10.3233/JAE-201556

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2020

Authors: Qiao, Yukai | Wang, Yinshun | Yuan, Xi | Zhang, Guangyi | Pi, Wei

Article Type: Review Article

Abstract: High temperature superconducting (HTS) magnets have widespread applications in a strong and steady magnetic field at low temperature. However, they can not be operated in persistent current mode (PCM) due to their immature joint technique without resistance. In order to realize the PCM, an HTS magnet stacked by double-hole rectangular HTS plates was proposed and fabricated. The trapped field of the HTS magnet was measured and simulated under four kinds of magnetization methods, field cooling (FC), zero field cooling (ZFC) and inner magnetization (a solenoid is placed at right/left hole of double-hole rectangular HTS magnet to magnetize HTS magnet) as …well as combination of both methods. Meanwhile, the H-formulation is applied to the 3D model to analyze the electromagnetic behaviour. It was found that the trapped field of double-hole rectangular HTS magnet magnetized by FC with inner magnetization or ZFC with inner magnetization is higher than pure FC or ZFC magnetization. In inner magnetization, the trapped field of one hole in HTS magnet has no effect on the other one. In addition, the experiment results are in good agreement with numerical analysis, which can provide significant references for the magnetization method. Show more

Keywords: Double-hole, FC, rectangular HTS magnet, trapped field, ZFC

DOI: 10.3233/JAE-201530

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2020

Authors: Alharbi, Khalid Hamed | Moniruzzaman, Md. | Aldhaheri, Rabah W. | Aljohani, Abdulah Jeza | Singh, Simranjit | Samsuzzaman, Md | Islam, Mohammad Tariqul

Article Type: Research Article

Abstract: In this paper, a monopole antenna with Ultra-wideband (UWB) characteristics is presented for applications in 5G and short-distance wireless communications. It consists of a rectangular shaped patch having truncated corners and central notch with an extended stub at top edge. Two layers of slots are engraved in the middle of the patch within which the outer layer contains four L shaped slots and the inner layer contains two face to face vertically placed U-shaped slots. A partial ground is structured with staircase slots to attain ultra-wideband response with sufficient gain and efficiency. The proposed antenna provides 124% of impedance bandwidth …(2.8 GHz–12 GHz) implemented on a low-cost FR4 substrate having the electrical dimension of 0.3𝜆 × 0.19𝜆 at the low cutoff frequency. The effect of the inclusion of slots within the patch is clearly observable as it increases gain and efficiency. The proposed antenna exhibits better response with a maximum measured gain of 6.5 dBi and efficiency 85% within the bandwidth. Near constant time delay around 1 nS and good fidelity factor of 0.8316 represents that this slotted antenna can be used for undistorted reliable signal transfer. This antenna also provides symmetrical radiation patterns with less cross-polarization effects. Therefore, this monopole antenna can be an appropriate candidate for short-range communication applications like 5G, wireless local area networks, transfer data from biomedical sensors and imaging. Show more

Keywords: Ultra-wideband, defected ground structure, monopole, slotted patch, 5G wireless communication

DOI: 10.3233/JAE-201553

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-22, 2020

Authors: Liu, Qing | Wang, Li | Zhang, Shiping | Li, Yuanyuan | Lei, Gang

Article Type: Research Article

Abstract: Active magnetic bearings (AMBs) bring extraordinary benefits such as free of contact, elimination of lubrication, active control of rotor position, and a built-in monitoring system. In the design of AMBs, the bearing structure is of significance since it has an important impact on bearing performances. However, the effect of winding configurations of AMBs is still obscure. In this paper, the system-level implications of two radial AMB winding configurations termed the Ortho and the Cross types are investigated, including the bearing characteristics, power consumptions and rotor dynamic behaviors. The simulation results demonstrate that the Cross type contributes to larger load capacity …in the direction of gravity. In condition of a heavier gravity load (−200 N), the Cross-type winding configuration saves power consumption with a percentage of 17.2% at steady state (20,000 rpm) and 12.7% considering unbalance mass during the run-up process. However, the rotor vibrations of the Cross type in case of external loads and unbalance mass are larger than the Ortho type. The proposed results of this paper provide some useful information for the AMB winding configuration design. Show more

Keywords: Active magnetic bearing, winding configuration, power consumption, rotor dynamics

DOI: 10.3233/JAE-201502

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-15, 2020