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

Authors: Li, Xiangchao | Cai, Lujin | Xu, Xiaopei | Wan, Zhicheng | Ma, Xiaoqi | Liu, Yinping

Article Type: Research Article

Abstract: Corona plays an important role in both initiation and development process of leaders around wind turbine blades. In this paper, based on laboratory experiments and numerical simulation, the corona triggering tests are performed by analyzing corona discharge characteristics of wind turbine blades. The corona threshold voltage and the corona current are measured. The corona environmental threshold and the corona triggering threshold are evaluated and discussed in detail. The influence of blade lengths, rotational angles and rotational speeds is analyzed. The results show that the corona trigger threshold obtained is a constant and is about 321.29 kV/m, which appears to be some fluctuations due …to atmospheric conditions and charged ions. In addition, through analysis the corona triggering threshold of different rotational angles and the corona environmental threshold of different rotational speeds, rotational wind turbine blades affect the electric field near the blades by varying the blade height and the charged ions distribution at the tip of the blades where the altered blade height accounts for the dominant factor. The above research results are valuable for the understanding of the initiation and development of leaders around the wind turbine blades. Show more

Keywords: Wind turbine blades, electric field distortion, corona discharge, corona triggering threshold, corona environmental threshold

DOI: 10.3233/JAE-180085

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2018

Authors: van der Horst, Menno Patrick | van Kreveld, Sylvia Lyanne | Kaminski, Miroslaw Lech

Article Type: Research Article

Abstract: Wireless crack monitoring on ships and offshore structures based on Self Magnetic Flux Leakage (SMFL) measurements is a promising method to guarantee the structural integrity in a more effective way, leading to reduced operational costs and increased safety. For accurate crack sizing, the SMFL measurements must be interpreted correctly, also during cyclic loading. Not much research has been done that focus on the effect of high cyclic stresses on the magnetization of ferromagnetic steels in weak magnetic fields. The aim of the research presented in this paper is to investigate the effect of stress-induced magnetization on the SMFL in the …stress concentration zone of a structural steel plate, and its implications for crack monitoring by the SMFL method. By means of an experiment, measured stress magnetization curves were obtained in a grid of points around an elliptical hole in a steel plate that was cyclically loaded up to the yield stress. The results show that the stress-induced magnetization causes a maximum variation of the measured signal of 25 μT, which is fully reversible. It is concluded that, depending on the application, this stress-induced variation may need to be taken into account for the interpretation of the measured signals by a crack monitoring system using the SMFL method. Show more

Keywords: Crack monitoring, self magnetic flux leakage, stress magnetization, ferromagnetic steel, cyclic loading

DOI: 10.3233/JAE-180031

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-18, 2018

Authors: Qiu, Li | Yu, Yijie | Li, Tao | Feng, Guang | Su, Pan | Chang, Peng | Deng, Changzheng | Xiong, Qi

Article Type: Research Article

Abstract: To improve the heating efficiency of the induction cooker system, this paper adopts the method of introducing an adiabatic layer between the pot bottom and the coil. By using COMSOL software, the electromagnetic - thermal coupling model of the induction cooker is established to analyze the effect of the adiabatic layer on the food temperature and coil temperature, and finally the heating efficiency is explored. The obtained simulation results show good agreements with the experimental results, and then the effectiveness of the proposed method is verified.

Keywords: Induction cooker, adiabatic layer, heating efficiency, electromagnetic - thermal coupling model

DOI: 10.3233/JAE-180072

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-10, 2018

Authors: Gandanegara, Grace | Rahmani, Mustapha | Gualino, David | Lechat-Sanjuan, Sylvain | Herriot, Yann | Guyon, Caroline Aubert | Dobrowolski, Jean | Dentella, Alain | Wang, Miao-Xin | Mazauric, Vincent

Article Type: Research Article

Abstract: Genset is usually used as the electricity generator and known for its stability thanks to its rotating inertia. With the population growth, the electricity demand is increased. Due to the limited amount of fossil energy resources and the climate-friendly issues, the renewable energy integration becomes higher. However, the intermittence of these resources can destabilize the grid. To integrate these renewable energies by behaving as genset with its rotating inertia, the Virtual Synchronous Machine concept is implemented in a microgrid.

Keywords: Virtual synchronous machine, microgrid, storage

DOI: 10.3233/JAE-171079

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-7, 2018

Authors: Tanaka, Yoshikazu | Koyama, Hiroaki | Odake, Satoru | Mutsuda, Hidemi | Popov, Atanas A. | Patel, Rupesh | McWilliam, Stewart

Article Type: Research Article

Abstract: In this paper, flexible piezoelectric devices (FPEDs) connected by springs are discussed with the aim of improving operational bandwidth of an energy harvesting system. A theoretical method, based on beam theory, electromechanical coupling and the transfer matrix method, is presented for calculating displacement and voltage responses. Validity of the presented method is discussed by comparison with experimental results, which are obtained from coupled FPEDs excited by a shaker. The effects on system behaviour of attaching springs is discussed based on both the presented method and experimental results.

Keywords: Piezoelectric film, flexible piezoelectric device, renewable energy, theoretical analysis method, forced vibration, engine vibration

DOI: 10.3233/JAE-171007

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-9, 2018

Authors: Vinsard, Gérard | Dufour, Stéphane

Article Type: Research Article

Abstract: A model to compute the forces between small and thin co-planar magnetic disks submitted to an uniform source magnetic field is built with the help of a pseudo magnetic dipole formula, in a similar way as the one used for beads. These forces are used to compute the motion of such disks floating on the top of a viscous liquid. Numerical results are compared to experimental data: it shows a good qualitative accordance.

Keywords: Magnetic dipole, demagnetizing factor, magnetic disk

DOI: 10.3233/JAE-171009

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-6, 2018

Authors: Mazauric, Vincent

Article Type: Editorial

DOI: 10.3233/JAE-171114

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-2, 2018

Authors: Wang, Cheng | Huang, Haiyang | Zhang, Tianshu | Chen, Yewang | Zhang, Yiwen

Article Type: Research Article

Abstract: To address the problems of singularities, sensitivity to measurement noise, and low efficiency in traditional principal component analysis (PCA)-based operational modal analysis (OMA), we present a Sanger neural network principal component analysis (SNNPCA) algorithm to identify the operational modal parameters. SNNPCA is a two-layer neural network that is trained using a generalized Hebbian algorithm to ensure that its output converges to the principal components. After SNNPCA has converged, the link weights of SNNPCA correspond to the separation matrix of PCA. In SNNPCA-based OMA, the measurement response points are set as the input neurons, modal coordinate response signals are set as …the output neurons, and the link weights of the neural network represent the modal shapes. Therefore, the operational modal identification process in SNNPCA is physically meaningful and convergent. Furthermore, SNNPCA inherits the parallel nature of neural network algorithms, so it is also insensitive to measurement noise. Simulation results show that SNNPCA can identify the principal modal parameters accurately using only measurement response signals. This method can be applied in embedded devices to realize online monitoring and real-time fault diagnosis. Show more

Keywords: Operational modal analysis, principal component analysis, Sanger neural network, generalized Hebbian rule, parallel, measurement noise

DOI: 10.3233/JAE-171011

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2018

Authors: Vesa, Joonas | Karhula, Taru | Marjamäki, Antero | Panchal, Jay | Rasilo, Paavo

Article Type: Research Article

Abstract: In this paper we describe an algorithmic method to imitate geometries of soft magnetic composites. We use microscope images to determine some of the most important geometric characteristics of the material and optimize the algorithm such that the measured and simulated characteristics are in agreement. We compute the static magnetization curves using the geometries obtained from the images and the algorithm comparing the results. The aim is to produce realistic geometries to be used in homogenization schemes as well as to study the effects of magnetic contacts in general.

Keywords: Geometry generation, homogenization, magnetic composite

DOI: 10.3233/JAE-171032

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-8, 2018

Authors: Yoshioka, Saijiro | Marumoto, Tatsuya | Gotoh, Yuji

Article Type: Research Article

Abstract: The crude oil which flows inside the steel tube of a heating furnace of an oil-refining plant is gasified by being heated with the burner from the surface outside the steel tube. Since this steel tube is used in Japan for 30 years or more, both the inner side and outer side of the steel tube is carburized. If the carburization depth is increased, the steel tube will be exploded suddenly and a big accident may occur. In this paper, the electromagnetic inspection method for measuring the carburized depth of both the inner side and the outer side of the …steel tube is proposed. The both depth is obtained by evaluating the flux density in layers with and without carburization in the steel tube using the 3-D nonlinear FEM. It is shown that the inspection for the both depth is possible by using the differential electromagnetic characteristics of the layers with and without carburization in the steel tube. Show more

Keywords: Electromagnetic non-destructive inspection, carburization steel tube, both surface and opposite side depth, 3-D finite element method

DOI: 10.3233/JAE-171112

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-8, 2018