International Journal of Applied Electromagnetics and Mechanics - Volume 49, issue 4

Authors: Gan, Jinqiang | Zhang, Xianmin

Article Type: Research Article

Abstract: Hysteresis behavior of piezoelectric actuators considerably degrades the precision positioning system's performance. Many hysteresis models are developed to describe rate-independent hysteresis, while few models are presented to characterize rate-dependent hysteresis. In this paper, a modified Prandtl-Ishlinskii model is developed to describe rate-dependent hysteresis in piezoelectric actuators. The modified model integrates input frequencies and quadratic polynomials. Meanwhile, the parameters of the developed model are identified easily by the experimental data using self-adaptive particle swarm optimization (SAPSO) and the least square method (LSM) through MATLAB offline. Compared with other models, this model simplifies the modeling of complicated rate-dependent hysteresis behaviors. The validity …of this developed model is demonstrated by comparing simulation results with experimental data at different frequencies in the range of 0.5-100 Hz. Show more

Keywords: Piezoelectric actuators, rate-dependent hysteresis, Prandtl-Ishlinskii model

DOI: 10.3233/JAE-150070

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 49, no. 4, pp. 557-565, 2015

Authors: He, Wei | Zhang, Yajie | Xu, Zheng | Cui, Xianjun | Luo, Haijun

Article Type: Research Article

Abstract: This paper presents a simple design for a nuclear magnetic resonance (NMR) sensor and its application for detecting turbine oil in two power stations. The magnet, which is composed of two identical cuboid permanent magnet blocks and two iron shimming sheets of a special shape, generates a relatively homogeneous static magnetic B0 field (∼ 364 ppm) on a 10 × 10 mm2 region of interest. In the vertical direction, it produces a constant gradient of ∼15.5 T/m within 5 mm which allows for self-diffusion measurements and 1 dimensional imaging. This NMR sensor can produce a deep penetration …depth into the samples with relatively strong and uniform B0 strength. The NMR sensor was specially designed for assessing the aging status of turbine oil in a power station, and a group of turbine oil of different service times was measured. Results demonstrate that an increase in the service time of the turbine oils clearly decreases transverse relaxation time T2 . This portable sensor can be used in fields and provide quantitative evaluation parameters of the aging status of turbine oil during periodic inspection. Show more

Keywords: Aging level, constant gradient, portable nuclear magnetic resonance (NMR) sensor, turbine oil

DOI: 10.3233/JAE-150080

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 49, no. 4, pp. 567-576, 2015

Authors: Zhou, Zupeng | Tan, Yonghong | Dong, Ruili | Zhang, Lieping

Article Type: Research Article

Abstract: In the real application, realizing the accurate fault prediction of non-smooth sandwich system with hysteresis which widely exists in the real engineering systems is of great importance. Therefore, a novel dynamic robust observer is proposed in this paper. First, the non-smooth sandwich system with hysteresis is transformed into a system in which conventional dynamic robust observer design method can be applied by converting the non-smooth item into a general disturbance. Then, by zeros assignment and minimizing the H∞, F /H-,F indicator on the basic operation zone, the feedback matrices of this observer can be obtained. After that, …the simulation results are presented. The comparison between the proposed robust non-smooth scheme and the conventional method demonstrated that the proposed robust fault detection approach can detect the actuator and sensor faults accurately and quickly which the conventional observer can not detect the faults at all. Moreover, the missing and false alarms are effectively reduced by the robust observer. Show more

Keywords: Robust observer, hysteresis, sandwich system, fault detection

DOI: 10.3233/JAE-150081

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 49, no. 4, pp. 577-595, 2015

Authors: He, Wei | He, Zhonghua

Article Type: Research Article

Abstract: A combination of passive shimming procedures is employed in the design of a unilateral Nuclear Magnetic Resonance magnet. The first shimming procedure used movable permanent magnets to correct the inhomogeneity of the B0 field to a relatively low level. In the second shimming procedure, the small iron pieces were used as shimming units, and their sizes and locations were predicted by using an integer programming method. Finally, the distribution of the shimming pieces was optimized and a special mathematic model was established. This hybrid technique provides a computational algorithm for optimizing the B0 homogeneity and for minimizing the number of …iron shimming pieces. A prototype unilateral NMR magnet has been built with this method. The B0 field measurement results were compared before and after the shimming. Employing this hybrid shimming method improved the uniformity of the B0 field from 4200 ppm to 796 ppm with only one iteration. Show more

Keywords: Passive shimming method, integer programming, unilateral nuclear magnetic resonance (UNMR)

DOI: 10.3233/JAE-150092

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 49, no. 4, pp. 597-606, 2015

Authors: Ezzat, M.A. | El-Bary, A.A.

Article Type: Research Article

Abstract: The model of the two-dimensional equations of magneto-thermoelasticity with fractional order heat transfer in a perfectly conducting medium is established. The method of the matrix exponential which constitutes the basis of the state-space approach of modern control theory is applied to the non-dimensional equations. Laplace and Fourier integral transforms are used. In this formulation, the governing equations are transformed into a matrix equation whose solution enables us to write the solution of any two-dimensional problem in terms of the boundary conditions. The resulting formulation is applied to a perfect conducting half-space problem. Some comparisons are shown in figures to estimate …the effects of the Alfven velocity and the fractional order on all the considered fields. Show more

Keywords: Magneto-thermoelasticity, new fractional taylor's series, state space approach, fractional calculus, numerical results

DOI: 10.3233/JAE-150095

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 49, no. 4, pp. 607-625, 2015

Article Type: Other

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 49, no. 4, pp. 627-633, 2015