International Journal of Applied Electromagnetics and Mechanics - Volume 45, issue 1-4

Authors: Zhang, Wenguang | Wu, Dongdong | Li, Zhengwei | Luo, Yun

Article Type: Research Article

Abstract: In this paper, a simple and low-cost method for improving the performance of the neural microelectrodes is reported. The electrochemical polymerization of conducting polymer PANI and MnO_2 (manganese dioxide) were performed to modify the surface of the microelectrode sites, then the morphology and electrical properties of the coated microelectrodes were investigated to analysize the influence of MnO_2 doping on the PANI coating. Results …show that, the surface morphology of PANI coating was improved by MnO_2 doping. Compared to the electrode with PANI, the charge injection capacity of the electrode with PANI-MnO_2 increased by about 7-fold and the impedance decreased to the original 1/6 (@ 1 KHz). The electrical properties were more stable and excellent with PANI-MnO_2 coating. Show more

Keywords: Neural microelectrode, conducting polymer, polyaniline, surface modification, electrical properties

DOI: 10.3233/JAE-141825

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 155-162, 2014

Authors: Shinagawa, Kazuki | Tanaka, Yoshikazu | Mutsuda, Hidemi

Article Type: Research Article

Abstract: A flexible piezoelectric device is proposed that can generate power from vibrations produced by vehicles or plants. The results of an experiment on a small and flexible piezoelectric power generator are presented herein. Forced vibration experiments were performed, and the results for the relationship between output power and vibration characteristics are discussed.

Keywords: Piezoelectric film, flexible piezoelectric device, renewable energy, vibration energy, forced vibration

DOI: 10.3233/JAE-141826

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 163-170, 2014

Authors: Tone, Ryota | Tanaka, Yoshikazu | Fujimoto, Yukio

Article Type: Research Article

Abstract: A nondestructive method that evaluates the distribution of plastic strain using an ultrasonic wave would be useful for estimating a structure's state prior to crack development. The authors have proposed an ultrasonic wave measurement method by combining an EMAT and PVDF, in which the couplant is not needed if a contact-type PVDF sensor is used. This paper reports on the comparison and examination of adhesion-type and contact-type PVDF sensors combined with an EMAT for …ultrasonic wave transmission. Show more

Keywords: EMAT, PVDF sensor, SH wave

DOI: 10.3233/JAE-141827

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 171-177, 2014

Authors: Cheng, Weiying

Article Type: Research Article

Abstract: Pulsed eddy current testing was carried out to inspect wall thinning. An excitation coil with a relatively small footprint was developed and used. An algorithm based on convolution and deconvolution operations was established to evaluate local wall-thinning.

Keywords: Pulsed eddy current testing, wall-thinning, deconvolution

DOI: 10.3233/JAE-141828

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 179-184, 2014

Authors: Murakami, Iwanori | Matsumoto, Shunya | Tomaru, Keiya | Ando, Yoshinori | Yamada, Kou

Article Type: Research Article

Abstract: Springs are used for various purposes, particularly for vibration control and the removal of machines. However, the use of a spring generates high amplitude at the resonance point; therefore, it is difficult to eradicate vibration from all frequency bands. To solve this issue, the variable rate spring was developed, which is composed of a magnetic spring. This variable rate spring can change the spring constant. Basically, the natural frequency of the vibration system fluctuates with changes …in the spring constant. As a result, the problem can effectively be resolved by changing the resonance point and eradicating the vibration. The variable rate spring is composed of a magnetic spring and a compression spring; the utility of this spring was verified by an experiment. Show more

Keywords: Magnets spring, variable rate spring, vibration control

DOI: 10.3233/JAE-141829

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 185-191, 2014

Authors: Wu, Jianbo | Kang, Yihua | Tu, Jun | Sun, Yanhua

Article Type: Research Article

Abstract: According to the Lenz's Law, eddy-current essentially exists in MFL (magnetic flux leakage) testing due to the relative movement between steel pipe and excitation coil, apparently affecting the MFL signals with the testing speed rising. Hence, the constitutive equation of eddy-current in the steel pipe was established by using Lenz's Law and it was found that: eddy-current in the arriving zone has the different direction from excitation current, resulting in the reduction of magnetization intensity; but …they have the same direction in the leaving zone, where the magnetization intensity is enhanced; and there is few eddy-current formed in the center; besides, the eddy-current density has direct proportion to the testing speed. Further, the effect on the MFL signal was investigated and it was shown that not only the magnitude but also the features are altered. Finally, a confirmation for the aforementioned analysis was conducted by numerical simulations. Show more

Keywords: Steel pipe, Hi-speed magnetic flux leakage (MFL), eddy-current, theoretical analysis, numerical simulation

DOI: 10.3233/JAE-141830

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 193-199, 2014

Authors: Cheng, Wenjie | Geng, Haipeng | Sun, Yanhua | Yang, Lihua | Yu, Lie

Article Type: Research Article

Abstract: To evaluate the rotor temperature field of a high speed permanent magnet synchronous generator (PMSG), an electromagnetic-eddy current-thermal coupled field model is constructed using 2D Time-stepping Finite-Element-Method (FEM). In the model, the electromagnetic field and the temperature field have the same meshed grids to make a node-to-node data transmission and are solved independently. The data transmission ensures the coupling of the fields and the solve order of these fields is controlled by an external program. …Temperature-dependent parameters, for example conductivity, can be set in the model. Windage loss of the rotor calculated by empirical formulas is loaded to the temperature field. Distribution of the rotor temperature is obtained by a calculation example of a 100 kW, 45000 r/min microturbine generator. Experimental data are used to show the validity of the proposed model which is helpful to the thermal design of the high speed PM generator. Show more

Keywords: Permanent magnet rotor, coupled field, eddy current loss, microturbine generator

DOI: 10.3233/JAE-141831

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 201-209, 2014

Authors: Sun, Pengfei | Wu, Xinjun | Xu, Jiang

Article Type: Research Article

Abstract: For the ultrasonic guided wave testing technology based on the magnetostriction effect, the structure of the sensor has a significant influence on its detectability. A structure for enhancing the received signal strength by encircling a magnetic concentrator around the coil is studied in this work. Based on theoretical analysis, influences of the magnetic permeability of the magnetic concentrator and the electrical conductivity on the signal strength are analyzed. Experiments are presented to verify the …analysis. Show more

Keywords: Guided wave, longitudinal mode, sensor, magnetic concentrator, pipe inspection

DOI: 10.3233/JAE-141832

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 211-217, 2014

Authors: Wei, Yanyu | Xu, Yongxiang | Zou, Jibin | Liu, Kai | Wang, Hao

Article Type: Research Article

Abstract: Commutation angle is a key design criterion when brushless DC (BLDC) motors sensorlessly operate based on the detection of back electromotive force (EMF) zero-crossing and must be designed significantly less than 30 electrical degree. The paper describes a detailed investigation on the commutation angle of brushless DC motors with 120° voltage source inverter. Analytic method is applied to analyze the influence factors. The proposed design principles can provide a clear guide for the adjustment of system …parameters. Then two criteria and an estimation method based on approximate anlytical solution of commutation angle are presented with experimental validation. Show more

Keywords: Commutation angle, brushless DC motor, 120° voltage source inverter, analytic analysis, criteria

DOI: 10.3233/JAE-141833

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 219-225, 2014

Authors: Wu, Xinjun | Ding, Xu | Wang, Li

Article Type: Research Article

Abstract: Electromagnetic acoustic transducer (EMAT) has been used in many industrial areas due to its non-contact nature. However, the longitudinal wave EMAT is rarely employed because it is difficult to be generated. An improved longitudinal wave EMAT is proposed in this paper. By inserting the copper sheet between the coil and the test specimen, the eddy currents induced in the test specimen are changed and the components of the eddy currents for generating the shear wave are …effectively suppressed. The performance of the EMAT is tested by the experiment. Show more

Keywords: Electromagnetic acoustic transducers (EMATs), longitudinal wave, shielding effect, eddy current, copper sheet

DOI: 10.3233/JAE-141834

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 45, no. 1-4, pp. 227-233, 2014