International Journal of Applied Electromagnetics and Mechanics - Volume 47, issue 4

Authors: Fu, Weinong | Chen, Yiduan

Article Type: Research Article

Abstract: State-of-the-art programming techniques of finite element methods (FEM) for electromagnetic field computation are presented. It covers program structure, data structure and algebraic matrix equation solver. The advantages of the proposed program structure are that multi-developers are empowered to work on different solvers and share common algorithms. The beauty of the proposed data structure are that two dimensional (2-D) FEM, multi-slice FEM and three-dimensional (3-D) FEM can share the same data structure. It allows quick access to all data and is efficient for organizing FEM programs and convenient for mesh generation. It can also deal with motion problems readily. The merits …of the matrix equation solver are that it can automatically deal with Dirichlet boundary conditions, master-salve boundary conditions and all other constraints in sparse matrix equations. The sub-matrix operation technique allows the electric circuit equations to be coupled easily with electromagnetic field equations. To couple the FEM with optimization method, a parameterized mesh technique is proposed to avoid mesh regeneration in the optimization progress. Show more

Keywords: Date structure, electromagnetic field, finite element method, mesh generation, programming, sub-matrix

DOI: 10.3233/JAE-130131

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 875-883, 2015

Authors: Yazdanpanah, Reza | Mirsalim, Mojtaba

Article Type: Research Article

Abstract: This paper presents an analytical field solution of an axial-flux hybrid excitation eddy current brake using the space harmonics of the magnetic vector potential. In the study, the analytical model is improved to take into account the 3-D effects that are neglected in the simplified 2-D model. Based on the analytical solution, the magnetic flux density distribution, the induced eddy current, and the generated braking torque are calculated. Also, the effects of two important parameters on the brake characteristic are investigated. Finite element analysis is employed to confirm the validity of the analytical analysis and the outcomes.

Keywords: Analytical study, brake design, eddy current, finite element, hybrid excitation

DOI: 10.3233/JAE-140019

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 885-896, 2015

Authors: Zhang, Chao | Qiu, Jinhao | Ji, Hongli | Shan, Shengbo | Zhao, Jinling

Article Type: Research Article

Abstract: A spatially distributed array of piezoelectric sensors is widely used in structural health monitoring (SHM) for active ultrasonic methods. Owing to many advantages of delay-and-sum algorithm such as intuition, low computation cost and accurate imaging result, it is very suitable for damage localization. However, due to the dispersion effect of Lamb waves, the wave packet becomes wide and distorted as it propagates in the structure which will have a negative effect in the spatial resolution of the damage imaging. This paper presents an active imaging method using warped frequency transform (WFT) to improve the spatial resolution of the imaging result. …In WFT, the warped frequency range is limited in narrowband and the central frequency is fixed to keep the wave packet undistorted. Then, the dispersion effect can be compensated and the velocity of the wave packet is converted into phase velocity which is much lower than group velocity. Due to the compensated wave packet and low wave velocity, the spatial resolution of the delay-and-sum algorithm is improved. Both single damage and dual adjacent damages are detected in the experiments. The comparisons between delay-and-sum algorithm with and without WFT are made to demonstrate the proposed method. Show more

Keywords: Lamb wave, damage localization, warped frequency transform, active structural health monitoring

DOI: 10.3233/JAE-140072

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 897-909, 2015

Authors: Hoole, P.R.P. | Thirukumaran, S. | Hoole, S.R.H.

Article Type: Research Article

Abstract: This work presents a self-consistent and self-contained model to study and analyse aircraft-lightning electrodynamics. An aircraft-circuit-model-based estimation of lightning currents is reported when the aircraft is struck by cloud-to-ground (CG) and ground-to-cloud (GC) lightning flashes. A distributed transmission line model for the aircraft and the return stroke channel of the lightning channel is used to simulate the return strokes of CG and GC flashes. It is observed that a higher magnitude of the rate of change in currents is produced due to the rapid discharge of electric charges on the lightning leader channel. Many GC return stroke currents eventually result …in a steady state current along the channel resulting in a large build up of induced voltage in avionics. It is further observed that the severity of threat to airborne devices is great in the case of the initial wave-front of CG return strokes. Previous lightning return stroke simulation units failed to consider the inclusion of aircraft as part of the long CG or GC lightning channel, which is crucial when considering the engineering design of the aircraft body and the protection of internal electronics where shielding is weakened by weakly shielding aircraft bodies. We report here for the first time a computer software simulation tool for studying lightning-aircraft dynamics for engineering analysis and design. Show more

Keywords: Lightning-aircraft dynamics, lightning return stroke, aircraft model transmission line model, aircraft-lightning interaction, frequency spectrum

DOI: 10.3233/JAE-140082

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 911-925, 2015

Authors: Zhu, H.-C. | Lan, J.-Q. | Wu, L. | Gulati, T. | Chen, Q. | Hong, T. | Huang, K.-M.

Article Type: Research Article

Abstract: The aim of the present work is to obtain effective permittivity of the reaction mixture during esterification reactions that can be used in a dynamic simulation environment and analysis the dielectric properties during the reaction process. Microwave heating serves as an excellent tool for carrying out such reactions and the multiphysics simulations need effective permittivity as one of the most important inputs. In this work, we perform the esterification reaction between ethanol, acetic acid and butyric acid using a temperature cycle in order to measure the effective permittivity of the reaction mixture. The obtained result is fitted using a bivariate …function of the concentration of one of the products of the reaction and temperature of the mixture. The computed results show good agreement with measured values with maximum errors for the synthesis reactions of ethyl butyrate and ethyl acetate being 4.94% and 3.68%, respectively. Show more

Keywords: Effective permittivity, microwave heating, multiphysics simulation, esterification reaction

DOI: 10.3233/JAE-140083

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 927-937, 2015

Authors: Cheng, Shih-Chieh | Lee, Kun-Chou | Huang, Chih-Wei

Article Type: Research Article

Abstract: In this paper, the radar target recognition is given by polarization-diversity RCS (radar cross section) including random effects. The polarization-diversity technique means that the RCS is collected by changing polarizations of transmitting and receiving antennas. The goal is to identify the similarity between the unknown and known targets. To increase discrimination and reducing random fluctuating components, collected polarization-diversity RCS data are processed by PCA (principal component analysis) technique prior to identification. Physically, polarizations of electromagnetic waves can access much information of targets. With the use of polarization-diversity RCS technique, it is not necessary to collecting RCS in many angular directions …(i.e., angular diversity), or at many frequencies (i.e., frequency diversity). Therefore, this technique is especially suitable for situations which have limitations on positions or frequencies. Numerical simulation results show that the proposed polarization-diversity target recognition scheme is very accurate in identifying targets. In addition, it has good ability to tolerate random fluctuating components. Compared with angular-diversity and frequency-diversity target recognition techniques, the polarization-diversity technique in this study requires less size of RCS databases so that computer resources are saved. Show more

Keywords: Target recognition, polarization diversity, radar cross section

DOI: 10.3233/JAE-140087

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 939-949, 2015

Authors: Shi, Junjie | Fan, Cuiying | Zhao, Minghao | Yang, Jiashi

Article Type: Research Article

Abstract: We study thickness-shear vibrations of a piezoelectric plate of AT-cut quartz with two pairs of electrodes. The plate represents a monolithic, two-pole acoustic wave filter. The scalar differential equations by Tiersten and Smythe for thickness-shear vibrations of electroded and unelectroded quartz plates are employed. Based on the variational formulation of the scalar differential equations established in a previous paper and the Ritz method with trigonometric functions as basis functions, free vibration resonant frequencies and thickness-shear modes of the plate are obtained. For a structurally symmetric filter, the modes can be separated into symmetric and antisymmetric ones. Trapped modes with vibrations …mainly under the electrodes are presented. The effects of the electrode inertia and the distance between the two pairs of electrodes are examined. It is also found that the classical frequency prediction given by Tiersten from an approximate analysis has an inaccuracy of tens of parts per million, significant in filter design and application. Show more

Keywords: Piezoelectric, resonator, filter, vibration

DOI: 10.3233/JAE-140090

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 951-961, 2015

Authors: Coelho, Marco Antonio Egito

Article Type: Research Article

Abstract: This paper describes a new type of magnetic levitation kit designed for teaching in undergraduate control laboratory at Universidade de Brasilia-Brazil. The kit can achieve stable levitation of a relatively heavy weight with very low power consumption and can also be used to teach on open-loop stable systems. The design allows good linear models and clearly shows to the student the power of feedback, because levitation is only possible in closed-loop. The transfer function of the magnetic part and the full block diagram are also proposed.

Keywords: Electromagnetic forces, feedback, magnetic levitation, stability

DOI: 10.3233/JAE-140106

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 963-973, 2015

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

Article Type: Research Article

Abstract: This paper proposes a scheme of fault detection for piezoceramic actuator described by so-called sandwich system models with hysteresis. In this scheme, the state variables of the system are estimated by a non-smooth observer due to the effect of hysteresis inherent in the piezoceramic actuator can not be neglected. The fault detection is based on the residual between the output of the observer and the actual data. In the simulation, the detection of the faults happened in actuator, i.e. input linear subsystem, output linear subsystem, and the output sensor are presented, respectively.

Keywords: Fault detection, sandwich systems, hysteresis, piezoceramic actuator

DOI: 10.3233/JAE-140138

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 975-991, 2015

Authors: Uchimoto, Tetsuya | Takagi, Toshiyuki | Takahashi, Yohei | Naganuma, Hiroshi | Sugawara, Kazufumi | Sasaki, Yoriaki | Douillard, Thierry | Masenelli-Varlot, Karine | Courbon, Jöel

Article Type: Research Article

Abstract: This paper discusses the feasibility of determining the thickness of Ni-based alloy sprayed coatings that have been heated in plant environments using swept frequency eddy current testing based on the measurement of the impedance spectrum of the measurement coil. Through a comparison of the experimental and computed signals, an electromagnetic model simulating the test geometry including the coating and the substrate is presented, with particular focus on the effects of heat treatment. Using these models, the coating thickness is estimated using the measured impedance spectra, and the estimation error was found to be around 30 μ m.

Keywords: Thermally sprayed coating, coating thickness, swept frequency eddy current testing, boiler tube environment

DOI: 10.3233/JAE-140050

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 4, pp. 993-1001, 2015