International Journal of Applied Electromagnetics and Mechanics - Volume 42, issue 3

Authors: Wahiduzzaman, Mohammad | Kamruzzaman, Md. | Alam, Md. Mahmud | Ferdows, M.

Article Type: Research Article

Abstract: This work has been numerically studied the fluid flow structure in the presence of magnetic field through a rotating rectangular straight duct under various flow conditions. Spectral method is applied as a main tool for the numerical calculation technique, where the Chebyshev polynomial, the Collocation method and the Newton-Raphson method are also used as secondary tools. The Magnetohydrodynamics incompressible viscous steady fluid flows in a straight duct of rectangular cross-section rotating at a constant angular …velocity about the center of the duct of the cross-section is numerically investigated to examine the combined effects of Magnetic parameter (M_g ), Rotational Parameter (T_r ), Pressure driven parameter (D_n ) and aspect ratio (γ)=b/a whereas a is the half width and b is the half height of the duct cross-section, Ω is the angular velocity, μ is the viscosity, ν is the kinematic viscosity. One of the interesting phenomena of the flow is the solution curve and the flow structure. The flow structures in case of small rotation of the duct axis and the pressure gradient with small Magnetic parameter as well as large Rotational Parameter and Large Magnetic Parameter have been considered while other parameters are remain constant. The calculations are carried out for 0.1⩽ M_g ⩽ 32000, 5⩽ T_r ⩽ 32000, D_n = 500, 1000, 1500, 2000,9000,10000,11000,12000 and 12500 where the aspect ratio γ =1.0. Show more

Keywords: MHD, straight duct, rotation, magnetic effect, spectral method

DOI: 10.3233/JAE-131666

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 327-342, 2013

Authors: Abdelmadjid, Nouicer | Elamine, Nouicer | Mouloud, Feliachi

Article Type: Research Article

Abstract: The magnetic behavior of materials is highly sensitive to the applied stress, which is subject of this paper. In magnetostrictive materials, the relationship B(H) is strongly related to the applied mechanical stresses. The purpose of this paper is to present a simple method to identify this relation for any value of stress σ. The proposed approach is based on the knowledge of the magnetic flux density spectrum for different stress σ. So, a feed-forward neural network …is trained to learn the relation between the rank of harmonics, stress and the amplitude of each harmonic. To construct the hysteresis loop for a new value of the stress σ, the neural network predicts the spectrum of the magnetic flux density B, which is transformed back to the time domain. Show more

Keywords: Discrete Fourier transform (DFT), magnetic hysteresis, magnetostrictive materials, neural networks

DOI: 10.3233/JAE-131667

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 343-348, 2013

Authors: Li, Ching-Lieh | Sun, Chi-Hsien | Chiu, Chien-Ching | Tuen, Lung-Fai | Su, Chien-Hua

Article Type: Research Article

Abstract: Two techniques for the shape reconstruction of multiple metallic cylinders from scattered fields are investigated in this paper, in which two-dimensional configurations are involved. After an integral formulation, the method of moment (MoM) is applied to solve it numerically. Two separate perfect-conducting cylinders of unknown shapes are buried in one half-space and illuminated by the transverse magnetic (TM) plane wave from the other half space. Based on the boundary condition and the measured scattered field, a …set of nonlinear integral equation is derived and the imaging problem is reformulated into optimization problem. The non-uniform steady state genetic algorithm (NU-SSGA) and asynchronous particle swarm optimization (APSO) are employed to find out the global extreme solution of the object function. Numerical results demonstrate even when the initial guesses are far away from the exact shapes, and the multiple scattered fields between two conductors are serious, good reconstruction can be obtained. In addition, the effect of Gaussian noise on the reconstruction results is investigated and the numerical simulation shows that the reconstruction results are good and acceptable, as long as the SNR is greater than 20 dB. Show more

Keywords: Inverse scattering, microwave image, buried conductors, asynchronous particle swarm optimization, genetic algorithms (SSGA), half space

DOI: 10.3233/TAD-131669

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 349-358, 2013

Authors: Deželak, Klemen | Štumberger, Gorazd

Article Type: Research Article

Abstract: This work deals with a new method that determines the optimal arrangements of overhead power line conductors by an optimization method called Differential evolution. During the optimization procedure the root mean square values of the electric field strength and the magnetic field density on the border of the overhead power line right of way are used as the main criteria. Both, electric and magnetic fields, are evaluated with methods, where the impact of conductor sagging is …considered. The position of the each power line conductor is determined in an optimization process. In the given case, the aim of optimization is to find such arrangement of conductors where the values of the electric and magnetic fields on the border of the overhead power line right of way are under the prescribed limits, whereas the tower height is as low as possible. Show more

Keywords: Optimization, overhead power lines, conductor sagging

DOI: 10.3233/TAD-131670

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 359-368, 2013

Authors: Geng, Yanbo

Article Type: Research Article

Abstract: The railgun system is an electromechanical coupled system. The electromagnetic field may cause an essential change of the dynamic behaviors of the railgun system. Here, considering the changes of the electromagnetic force caused by the rail displacement, the electromechanical coupled dynamic equations for the rail are given. Using these equations, the natural frequencies of the railgun system and their changes along with the system parameters are investigated, the vibration modes of the railgun system are …discussed, and the forced responses of the rail to the running electromagnetic force are analyzed. The results show that the moving electromagnetic force causes the changes of the natural frequencies for the railgun system. As the armature moves, the vibration modes of the rail are change as well. The electromechanical coupled effects change the forced responses of the rail to the running electromagnetic load. The effects are more obvious for larger armature distance and current, small distance between the two rails and stiffness of the elastic foundation. The results are useful for design and application of the railgun system. Show more

Keywords: Railgun, dynamics, forced response, rail, electromechanical coupled

DOI: 10.3233/TAD-131671

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 369-389, 2013

Authors: Yamashita, Norio | Yamamoto, Akio | Higuchi, Toshiro

Article Type: Research Article

Abstract: This paper analyzes pulse voltage operations of a two-to-four phase voltage-induction-type electrostatic motor (VITEM) to clarify the appropriate driving sequences. The paper also evaluates transient charge effects that can possibly enhance the thrust force. VITEM has been studied as a novel centimeter-sized electrostatic film motor whose power to the slider is supplied indirectly through its induction electrodes. Since a smooth synchronous driving was aimed in the past studies, high-frequency AC voltages have been used for …the driving. This paper demonstrates that straightforward usage of simple pulse sequences cannot realize continuous stepping driving, and proposes several different sets of modified pulse sequences to realize continuous stepping driving using low-switching-rate pulse voltages. In the experiments, the motor showed continuous stepwise driving with a step width of about half of the electrode pitch. In addition, transient characteristics of charges on films were evaluated experimentally under the pulse driving condition, and contribution for thrust force enhancement was clarified. Show more

Keywords: Pulse voltage, electrostatic motor, two-to-four phase, voltage induction

DOI: 10.3233/TAD-131672

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 391-408, 2013

Authors: Chan, Sheng-Chih | Lee, Kun-Chou

Article Type: Research Article

Abstract: In this paper, radar target recognition is given by KSDA (kernel scatter-difference discriminant analysis) pattern recognition on RCS (radar cross section). The kernel method converts the traditional FLDA (Fisher linear discriminant analysis) to a nonlinear high-dimensional space and such a kernel technique is called KFDA (kernel Fisher discriminant analysis). The basic concept of KFDA is to map training samples in the original space to a high-dimensional feature space via a nonlinear mapping function. Pattern …recognition is then implemented in the feature space through extracted nonlinear discriminant features. However, as the kernel within-class scatter matrix is singular, the optimal discriminant features can not be achieved directly. To improve this drawback of KFDA, this study utilizes the scatter difference as the discriminant function, i.e., KSDA, to implement radar target recognition. The KSDA can modify the Fisher discrimination function and then serves as an efficient tool of radar target recognition. As a result, the computational complexity is reduced and then the computational speed is increased. Of great importance, the proposed target recognition scheme (based on KSDA) can still work well even though the kernel within-class scatter matrix is singular. Our KDSA based target recognition scheme is accurate, efficient and has good ability to tolerate random noises. Show more

Keywords: Kernel scatter-difference discriminant analysis, radar cross section, radar target recognition

DOI: 10.3233/JAE-131673

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 409-420, 2013

Authors: Olaru, R. | Gherca, R.

Article Type: Research Article

Abstract: In this paper is presented an extensive theoretical study and some experimental results regarding an electromagnetic generator based on levitated magnet, designated to harvest energy from ambient vibrations. Generator optimization for achieving the maximum values of transmissibility and electrical power was performed by considering a resonance frequency different from the natural frequency that is usually used in literature. The step response of the system, described analytically, is useful in the analysis of …generators subject to sudden variations of the random vibration amplitude. The obtained experimental results indicate the possibilities of optimization and increase of the device power depending on the frequency and amplitude of external vibrations. The generator with levitated magnet studied in this paper, provided a maximum power of 27 mW when working as a quasi-linear oscillator and of 64 mW, respectively, when working as a non-linear oscillator. Show more

Keywords: Energy harvesting, levitated magnet, resonance phenomenon, nonlinear oscillator

DOI: 10.3233/JAE-131674

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 421-435, 2013

Authors: Taherdangkoo, Mohammad

Article Type: Research Article

Abstract: In this paper, we propose a new method for solving the Loney's solenoid benchmark problem based on stem cells algorithm (SCA). The key idea of the algorithm is using a modified version of our proposed stem cells optimization method that can efficiently achieve the best solution for the position and size of two correcting coils in the famous Loney's solenoid problem. The results show the superiority of the proposed method on other previously proposed methods for …electromagnetic optimization. Show more

Keywords: Meta-heuristic algorithm, modified stem cells algorithm, Loney's solenoid problem, beta distribution

DOI: 10.3233/TAD-131675

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 437-445, 2013

Authors: Yin, Xiaokang | Hutchins, David A | Chen, Guoming | Li, Wei

Article Type: Research Article

Abstract: As a novel electromagnetic non-destructive evaluation (NDE) technique, capacitive imaging (CI) has been successfully used on a various types of materials, including concrete, glass/carbon fibre composite, steel, etc. In this work, studies on the design principles for the CI probes were presented. Firstly, measures for the evaluation of the CI probe performance are presented. The concept of volume of influence is then raised, to evaluate the imaging ability of a given CI probe. Examples of CI …probe designs are then provided, namely symmetric and concentric geometries. Design factors, such as separation between electrodes, guard electrodes, and electrode shapes are also discussed and examined experimentally. CI scans were performed on two typical specimens, namely Perspex and aluminium, to evaluation the imaging performance of CI probes with different geometries. Show more

Keywords: Capacitive imaging, coplanar probe; probe design, non-destructive evaluation

DOI: 10.3233/JAE-131676

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 42, no. 3, pp. 447-470, 2013