International Journal of Applied Electromagnetics and Mechanics - Volume 33, issue 3-4

Authors: Hu, Jie | Zhang, Xi-Nong | Xie, Shi-Lin

Article Type: Research Article

Abstract: The main idea of the paper is to identify the load in time domain through inversely analyzing the Duhamel integral process, a time domain algorithm is developed without tedious theoretical derivation, the simulated results show that the proposed method is effective and of high accuracy.

DOI: 10.3233/JAE-2010-1216

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1025-1032, 2010

Authors: Zhou, Guohua | Xiao, Changhan | Liu, Shengdao | Liu, Daming

Article Type: Research Article

Abstract: Our goal is to obtain the magnetic field distribution below ferromagnetic hull ships based on planar field measurements. A magnetic inverse model based on equivalent magnetic surface charge was presented to extrapolate the magnetic field at different depths below ferromagnetic hull ships. In order to improve the robustness of the magnetic inverse model, regularization methods were applied to solve the inverse problem. It is shown by a numerical example and a mock-up experiment that the …proposed method is satisfying in modeling of ferromagnetic hull magnetism. Show more

Keywords: Magnetic field extrapolation, magnetic surface charge, inverse problem, regularization method

DOI: 10.3233/JAE-2010-1217

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1033-1040, 2010

Authors: Zhou, Mingxing | Zhou, Jianjiang | Zhang, Xiao | Wang, Fei

Article Type: Research Article

Abstract: The purpose of this paper is to establish a more suitable method for estimating the lunar regolith depth from microwave radiation brightness temperature data of the lunar surface. The physical properties of the lunar surface influencing on the brightness temperature are comprehensively discussed. Considering the variation of these influence factors, an inhomogeneous multi-layer microwave radioactive transfer model is used to inverse the thickness of lunar regolith. By applying fluctuation dissipation theorem, the …relationship between the microwave radiation brightness temperature of the lunar regolith and the thickness and temperature of lunar regolith based on this multi-layer model is theoretically deduced. The brightness temperatures of the lunar regolith obtained from Chang'E-1 satellite are simulated on the basis of aforementioned works. An approximate function of inversion is presented. Taking these simulation results with random noise as observation data, an inversion method of the lunar regolith-layer thickness is developed. It indicates that the inverse ability of a certain frequency channel depends on the microwave penetration depth of this frequency channel. The thickness within the penetration depth can be accurately inversed. Using part of the brightness temperature data measured by the microwave radiometer on the Chang'e-1 satellite, the primary result of the lunar regolith thickness distribution is figured out. Show more

DOI: 10.3233/JAE-2010-1218

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1041-1048, 2010

Authors: Liu, Lei | Lu, Junwei | Yang, Shiyou | Ni, Guangzheng

Article Type: Research Article

Abstract: The design of dual-frequency band Inverted-S Antennas (ISA) involves a great deal of tuning works. In this point of view, two optimal methodologies are proposed to synthesis this type of antennas in a more efficient way. The two optimal methodologies, one based on a vector optimizer and the other on scalar optimizer, take advantage of a novel formula to optimize the bandwidths in dual bands. The scalar methodology employs some constraint handling technique to improve its …speed of convergence, while the vector methodology without using any preference information strives to accelerate its convergence by means of response surface models. The comparison of numerical results shows the feasibility of the proposed optimal methodology for ISA synthesis. Also, the advantages and limitations of the methodologies are discussed. Show more

Keywords: Inverted-S antenna, evolutionary algorithm, constraint handling, response surface model

DOI: 10.3233/JAE-2010-1219

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1049-1055, 2010

Authors: Yang, Shiyou | Wu, Lie | Yang, Lin | Xiong, Suming

Article Type: Research Article

Abstract: This paper proposes a particle swarm optimization algorithm to find the robust solution of an inverse problem in which uncertainties or perturbations are inevitable. To reduce the heavy computational burden for expected fitness evaluations, a strategy to assign expected fitness only to the best solution searched by a particle in every iterative cycle is proposed, a repository is introduced to memory the searched history and then employed to determine the expected fitness value of a specific …solution. The simplex method is used to find the worst case solution of a potential candidate to consider hard constraint functions. The numerical results serve to demonstrate the pros and cons of the proposed algorithm and the necessity to devote efforts in the development of robust oriented optimal algorithms. Show more

Keywords: Robust design, particle swarm optimization, inverse problem, optimization

DOI: 10.3233/JAE-2010-1220

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1057-1062, 2010

Authors: Zhang, Wei | Yang, Shiyou | Bai, Yanan | Machado, José Márcio

Article Type: Research Article

Abstract: This paper explores firstly the potential of a new evolutionary method – the Cross-Entropy (CE) method in solving continuous inverse electromagnetic problems. For this purpose, an adaptive updating formula for the smoothing parameter, some mutation operation, and a new termination criterion are proposed. The proposed CE based metaheuristics is applied to reduce the ripple of the magnetic levitation forces of a prototype Maglev system. The numerical results have shown that the ripple of the magnetic …levitation forces of the prototype system is reduced significantly after the design optimization using the proposed algorithm. Show more

Keywords: Cross-entropy method, global optimization, design optimization, evolutionary algorithm

DOI: 10.3233/JAE-2010-1221

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1063-1068, 2010

Authors: Meng, Xiangjun | Wang, Shuhong | Qiu, Jie | Zhu, Jian Guo | Guo, Youguang

Article Type: Research Article

Abstract: Cogging torque in permanent-magnet brushless DC (BLDC) motor causes torque and speed ripples, as well as acoustic noise and vibration, especially in low speed and direct drive applications. In this paper, the stator core shape is optimized by using a level set based topology optimization to reduce cogging torque. The level set method can represent the precise boundary shape of structure and also deal with complex topology changes during the optimization process. Different from the conventional …rectangular meshes, the level set technique based triangular finite element meshes are presented in this paper to deal with irregular domains. The comparison of cogging torque calculated before and after topology optimization verifies the advantages of the level set topology optimization based on triangular meshes. Show more

Keywords: Topology optimization, level set, adjoint variable, cogging torque

DOI: 10.3233/JAE-2010-1222

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1069-1076, 2010

Authors: Pei, Cuixiang | Chen, Zhenmao | Wu, Wenjing | Mao, Ying

Article Type: Research Article

Abstract: In this paper, a code of finite element method is developed for numerical simulation of electromagnetic acoustic testing (EMAT) signals. In order to improve the simulation efficiency of ultrasonic field, a new explicit integration algorithm of time domain is introduced in the simulation code. As an extending application of EMAT to the quality control of Thermal Barrier Coating (TBC), the feasibility of an EMAT transducer, which is proposed for detecting delaminating defect in TBC, is investigated …by using the new code. Show more

Keywords: EMAT, nondestructive testing, finite element method, thermal barrier coating, numerical simulation method

DOI: 10.3233/JAE-2010-1223

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1077-1085, 2010

Authors: Kikuchi, Hiroaki | Kurisawa, Yumi | Ara, Katsuyuki | Kamada, Yasuhiro | Kobayashi, Satoru

Article Type: Research Article

Abstract: This paper discusses a feasibility of magnetic flux leakage (MFL) method for estimation of wall thinning on tube in nuclear power plant. A single magnetic yoke is fixed on the specimen, and then a magnetic field sensor scans the leakage field between the yoke legs. The single magnetic yoke with gauss meter fixed at the center of the yoke is also scanned over specimens having a slit. From both FEM analysis and experimental measurement, it is clarified that …estimation of the size of slit fabricated in the specimen using profile of leakage field is possible; this indicates monitoring conditions of wall thinning will be possible by MFL method. Show more

Keywords: Wall thinning, magnetic flux leakage (MFL), condition monitoring

DOI: 10.3233/JAE-2010-1224

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1087-1094, 2010

Authors: Huang, Songling | Tong, Yun | Zhao, Wei | Wang, Shen

Article Type: Research Article

Abstract: Due to the engineering demand of oil and gas pipeline crack inspection, a new ultrasonic method based on non-contact ultrasonic transducer known as EMAT has emerged. Because of the large amount of original waveform data and limited speed and capacity of storing device, research on online data compression is needed. A subsection adaptive compression algorithm based on the features of the inspection data is proposed. The compression precision can be adjusted by altering compression threshold. Compression …experiments of 250 kHz EMAT guided wave data are conducted using this algorithm. The results indicate that the algorithm has good quality, and can achieve rather high compression ratio at the same time. A compression ratio around 20:1 can be achieved on sample data. Compression quality evaluation is performed using error sequence and PSNR. Show more

Keywords: Data compression, peak signal to noise ratio (PSNR), pipeline inspection, electromagnetic acoustic transducer (EMAT)

DOI: 10.3233/JAE-2010-1225

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 3-4, pp. 1095-1100, 2010