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

Authors: Kawaguchi, Hideki

Article Type: Research Article

Abstract: This paper proposes a scattered field formulation of the finite-difference time domain method (S-FDTD) combining with a time-domain electric field integral equation (TD-EFIE) based on surface equivalence theorem. The scattered field formulation enables us to reduce computation cost effectively for the case that scatterers are located at a far distance from field sources of electromagnetic wave since we need to calculate the scattered field component only on the region in the vicinity of the scatterers. Then it is required for the use of the scattered field formulation that the field source for the incident field component has to be expressed …by any analytical solutions such as a point dipole source, plane wave, and so on. In this work, the scattered field formulation of the FDTD method is applied to cases that there are no analytical expressions of the field sources, in which the field source contains conductors such as antennas, combining with the TD-EFIE on a virtual surface which encloses the field sources. Then, it is known that calculation of the TD-EFIE itself is time consuming. This paper considers speed-up of the S-FDTD simulation based on the TD-EFIE using a spherical harmonic expansion of Green’s function of Helmholtz equation, additionally. Show more

Keywords: Finite-difference time-domain method, microwave propagation, scattered field formulation, surface equivalence theorem, time-domain electric field integral equation, spherical harmonic expansion, Green’s function of Helmholtz equation

DOI: 10.3233/JAE-190164

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-9, 2020

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

Article Type: Research Article

Abstract: This paper investigates the braking force characteristic of permanent magnet eddy current brake with high acceleration. Compared with the braking force characteristics under quasi-static condition, the braking force considering the effect of high acceleration lags behind the quasi-static braking force before and after the critical speed. Meanwhile, there is a transition phase near the critical speed, and the peak value of the braking force is higher than that in the quasi-static approximation. The calculation of braking force under quasi-static condition is derived by solving the boundary value problem. The accuracy of the analytical model and the finite element model is …verified through comparing the results of both models. The influence factors on the braking force characteristics are further analyzed. The results show that the increasing of the conductivity, thickness of conductor plate and the length of the permanent magnets can increase the effect of acceleration. The effect of acceleration has little relation with the permanent magnet height and the air gap length. Show more

Keywords: Eddy current brake, electromagnetic force analysis, high acceleration, permanent magnets

DOI: 10.3233/JAE-190141

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

Authors: Du, Chuanbao | Liu, Zheng | Mao, Congguang | Qin, Feng | Cui, Zhitong | Sun, Dongyang

Article Type: Research Article

Abstract: This paper examines with statistical analysis of transient response for typical vehicle mounted antenna - monopole on conductive plane varying multiple random field parameter distributions of high-altitude electromagnetic pulse (HEMP) by employing the combinations of Method of Moment (MoM) method and a high computational efficiency statistical analysis tool called polynomial chaos expansion method (PCEM).The main procedures of the combination method are composed of two following steps: Firstly, the frequency-domain transfer function of the antenna port response for the monopole is derived by using MoM and then the transient current response is obtained with inverse Fourier transform; Secondly, the statistical model …with multiple random input parameters are calculated by PCEM according to the transient response data. The statistical indicators of the model concentrate on the confidence interval of the transient response, the Probability Density Function (PDF) and Cumulative Probability Density Function (CDF) of the current peak. The paper not only focuses on the random radiated field parameter such as elevation, azimuthal angle, polarization angle and magnetic dip angle but also considers height of burst, ratios of plane length versus antenna height, and antenna down-tilt angles. The analysis results demonstrate the validation of the proposed statistical method and provide the reference base for system HEMP survivability evaluation and protection design. Show more

Keywords: Monopole, HEMP, uncertainty analysis, MoM, PCEM, transient response

DOI: 10.3233/JAE-190125

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