International Journal of Applied Electromagnetics and Mechanics - Volume 47, issue 1

Authors: Kim, Tae Heoung

Article Type: Research Article

Abstract: A 3-phase flux-reversal motor (FRM) driven by a 6-switch converter has been studied for its various merits such as a low inertia, a high efficiency and fault tolerance. However, it is needed to develop the FRM with a 4-switch converter to reduce motor and converter construction costs. Among the many different 4-switch converter topologies, the one with a compensated current regulation base on a novel pulse width modulation (PWM) control technique has been proposed as a …good solution. In this paper, we introduce a two dimensional time-stepped voltage source finite-element method (2D-FEM) to analyze the FRM driven by the proposed 4-switch converter. We also compare the characteristics of the FRM when the compensated current regulation is adopted or not. To verify the analysis method and simulated results, the 4-switch converter and the prototype FRM are built and experiments are performed. Show more

Keywords: Flux-reversal machine, 4-switch converter, finite element method

DOI: 10.3233/JAE-130065

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 1-9, 2015

Authors: Sharma, Ashish Kumar | Gupta, Navneet

Article Type: Research Article

Abstract: An improved design of microelectromechanical system (MEMS) switch for radio frequency (RF) applications has been proposed using non-uniform serpentine flexure structure. An analytical modeling of non-uniform serpentine flexure is obtained using small displacement theory and is compared with finite element method (FEM). It is observed that in comparison to the uniform serpentine flexure reported so far, the proposed design shows a considerable reduced spring constant of 0.65 to 0.04 N/m and pull-in voltage of 15 to …3 V with better RF power handling capabilities of 4.29 to 0.2 W for span beam length varying from 100 to 280 μm. The proposed switch design shows with better RF response in terms of return loss of −20 dB and isolation of −40 dB at 26 GHz. Show more

Keywords: MEMS switch, FEM, radio frequency, spring constant

DOI: 10.3233/JAE-130085

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 11-19, 2015

Authors: Mahmoodi, Mostafa | Esfe, Mohammad Hemmat | Akbari, Mohammad | Karimipour, Arash | Afrand, Masoud

Article Type: Research Article

Abstract: Magnetohydrodynamic natural convection fluid flow and heat transfer in a square enclosure with a pair of source and sink on its walls, filled with liquid Gallium fluid with Prandtl number of 0.02 has been investigated numerically. The heat source and heat sink are maintained at a constant temperature T_{h} and T_{c} , respectively with T_{h} > T_{c} . By variation of relative location of the heat source and sink on the walls …of the enclosure, five different cases are generated. The governing equations written in terms of the primitive variables are solved numerically using the finite volume method and the SIMPLER algorithm. Using the developed code, a parametric study is performed, and the effects of the Rayleigh number, the Hartman number, and the locations of the source and sink on the fluid flow and heat transfer inside the enclosure are investigated. The results show that the flow and temperature distributions inside the enclosure are affected by the strength of the magnetic field, the Rayleigh number, and the relative location of the heat source and sink. The magnetic field decreases the rate of heat transfer, suppresses the convection heat transfer, and tends to slows down the flow velocity in the cavity. Moreover in some cases the magnetic field changes the flow pattern inside the enclosure. Show more

Keywords: Magnetic field, natural convection, square enclosure, heat source, heat sink

DOI: 10.3233/JAE-130097

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 21-32, 2015

Authors: Tang, Mingsheng | Zou, Huiming | Xu, Hongbo | Shao, Shangquan | Tian, Changqing

Article Type: Research Article

Abstract: The electromagnetic transduction coefficient has a strong influence on efficiency as well as the sensorless control of linear oscillation electrical machine (LOEM). This paper presents a reciprocal LOEM method for measurement of the electromagnetic transduction coefficient, to investigate the effect of the magnet length on the characteristics of the transduction coefficient. The result shows that the transduction coefficient has two regimes, a constant regime and a nonlinear regime. As the harmonic distortion …begins to appear in the induced electromotive force, the electromagnetic transduction coefficient passes from the constant regime to the nonlinear regime, and the corresponding stroke is defined as critical stroke. The range of constant regime equals the observed critical stroke, and the critical stroke is 8.81 mm and 10.78 mm when the length of the permanent magnet is 11 mm and 13 mm respectively. The relationship among the geometrical dimension of yoke and permanent magnet, the critical stroke and the stroke of the LOEM are carefully investigated. Then optimal lengths for both the yoke and the permanent magnet are suggested for the LOEM design with the rated stroke, to achieve the highest efficiency and least material cost simultaneously. Show more

Keywords: Electromagnetic transduction coefficient, magnet length, nonlinear characteristic, harmonic distortion

DOI: 10.3233/JAE-130110

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 33-43, 2015

Authors: Muthu, Ganesh Madhan | Kumar, Jagadeesh Velan | Jayaraman, Roopchand

Article Type: Research Article

Abstract: Radar Cross Section (RCS) computation and analysis are carried out for a high speed, kinetic energy missile at 35 GHz. The radar cross section simulations were performed under bistatic conditions, using a 3D Electromagnetic field solver. RCS values for standard geometries such as cylinder, cone – cylinder combination are calculated under different excitation conditions and the results are verified with literature, so as to fix the settings in the solver. A maximum RCS value for the …missile is obtained as −4.9 dBsm under broad side excitation. RCS values of −22.25 dBsm and 4.94 dBsm are obtained for 0° (Nose cone) and 180° direction, when excited in the frontal region, i.e., 0° azimuth and 0° elevation. Further, monostatic simulation under 0° to 180° excitation shows a large RCS value of −4 dBsm at 90°, corresponding to large surface area of the missile. The effect of frequency on the RCS of the missile is also determined in 30 to 40 GHz band. A comparison of integral equation solver and asymptotic solver for RCS computation indicates almost similar values, with a deviation less than 5 dB in most of the ranges. However, with compromise on accuracy, the asymptotic solver is found to consume only 5% of the total time required by integral equation solver. Show more

Keywords: Radar cross section, electromagnetic field solver, kinetic energy missile, Ka band, active protection system

DOI: 10.3233/JAE-130139

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 45-59, 2015

Authors: Xu, Ming-Xiu | Chen, Zhang-Hua | Xu, Min-Qiang | You, Tian-Qing

Article Type: Research Article

Abstract: In metal magnetic memory (MMM) detection, the Jiles-Atherton model describes material magnetization caused by the geomagnetic field and cyclic stress. However, characterization of the effects of fatigue damage on magnetization remains an issue. In this paper, an expression for magnetization intensity M_{0} related to dislocation and plastic strain amplitude ε_{p} was incorporated into a modified Jiles-Atherton model. To validate the M_{0} expression, …standard tensile fatigue tests were performed. Results indicate that the domain wall pinning parameter k_{1} in M_{0} is linear in both dislocation density ρ and average dislocations slippage distance �λ, as is also the shear plastic strain amplitude in the stress control fatigue. The stress amplitude in strain control fatigue however is linear with respect to ρ^{1/2} . Therefore, M_{0} can be expressed as a function of stress and ε_{p} (or �λ and stress amplitude). Experiments showed that calculated M_{0} variations in fatigue development processes can reflect a variation law in the MMM signal, with certain differences. There is a numerical difference between H_{px} and M_{0} because the surface magnetic field is much weaker than that within the ferromagnetic material. H_{px} increases after macro crack initiation caused by an additional material demagnetization field and a leakage field near the crack during cracking. Show more

Keywords: Fatigue, metal magnetic memory, Jiles-Atherton model, dislocations

DOI: 10.3233/JAE-130159

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 61-73, 2015

Authors: Jin, Longwen | Lei, Bin | Li, Zhiyuan | Zhang, Qian

Article Type: Research Article

Abstract: An analytical model is proposed to investigate the dynamic behavior of rail under the effect of both the rail repulsive force and the armature contact force. The rail is modeled as a Bernoulli – Euler beam resting on a continuous elastic foundation with simply support at both ends of the rail. Numerical simulations are carried out using the analytical model at below, near and above the critical velocities respectively. The results show that the dynamic response …of the rail under the effect of both the repulsive force and contact force is more intensive and complicated than the case in which only the repulsive force acted. The additional oscillations caused by the contact force may increase the possibility of electrical contact failure between the armature and the rails. For more detailed analysis, the analytical model is needed to take into account the varying elastic stiffness and damping effect of practical railgun structure. Show more

Keywords: Dynamic response, critical velocity, armature movement, railgun

DOI: 10.3233/JAE-130168

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 75-82, 2015

Authors: Fiaz, M.A. | Ashraf, M.A.

Article Type: Research Article

Abstract: An analytic technique based on spectral plane wave representation of fields (SPRF) for the scattering of a plane wave from a perfectly electric conductor (PEC) cylinder coated with double positive (DPS) or double negative (DNG) materials buried beneath a slightly rough surface is formulated. Small Perturbation Method is used to consider scattering from rough surface. Spectral integrals are evaluated using saddle point method. A comparison with the previously available results has been done for validity. Both …TM and TE polarizations are considered to obtain results varying different geometrical and physical parameters. Show more

Keywords: Scattering, rough surface, DNG, buried object

DOI: 10.3233/JAE-130171

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 83-93, 2015

Authors: Ezzat, Magdy A. | El-Karamany, Ahmed S. | El-Bary, Alaa A.

Article Type: Research Article

Abstract: Some mathematical models of the equations of generalized magneto-thermo-viscoelasticty for isotropic media are given. The formulation is applied to each generalization of the Lord- Shulman theory, the Green-Lindsay theory and the Chandrasekharaiah and Tzou theory as well as to the coupled theory. The state space approach is adopted for the solution of problems in the absence or presence of heat sources. The Laplace-transform technique is used. A numerical method is employed for the inversion of the …Laplace transforms. Numerical results for the stress distribution are given and illustrated graphically for each problem. Comparisons are made with the results predicted by the four theories. Show more

Keywords: Generalized thermoelasticity, magneto-thermo-viscoelasticity, Lord-Shulman theory, the Green-Lindsay theory, chandrasekharaiah and tzou theory, coupled theory, state space approach

DOI: 10.3233/JAE-130177

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 95-111, 2015

Authors: Silva, Anderson O. | Cardoso, Markos P. | Giraldi, Maria T.M.R. | Costa, João C.W.A.

Article Type: Research Article

Abstract: Surface plasmon-polariton excitations are electromagnetic modes responsible for a huge field confinement at the interface between a conductor and a dielectric. These modes mitigate light scattering even below the diffraction limit, which allows the reduction in size of several kinds of electromagnetic devices such as waveguides, resonators and sensors. Within this framework, we apply the FEM-RBCI formulation to investigate the response at the optical spectrum of a nanocavity filled with silver nanodisks. Computational …simulations show that the coupling between localized surface plasmon modes excited at the periphery of the nanodisks yields a high sensitivity degree in an ultra-compact area. Such sensitivity is nearly constant and covers a wide range of refraction indexes of the surrounding medium. Furthermore, it is not required any external phase matching technique to achieve surface plasmon resonance. These characteristics demonstrates the great potential of the structure to improve optical sensing applications. Show more

Keywords: Localized surface plasmon modes, nano-optical devices, refraction index sensors, FEM-RBCI method

DOI: 10.3233/JAE-130182

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 113-123, 2015

Authors: Li, Ping | Gao, Shiqiao | Cai, Huatong | Cui, Yan

Article Type: Research Article

Abstract: MEMS piezoelectric energy harvester is optimally designed and fabricated, and its vibration characteristics, output voltage, power, power spectral density (SD) and frequency response function under harmonic and random excitation is studied by theory analysis, simulation and experimental test. For the designed MEMS piezoelectric energy harvester, the accurate solutions and expressions of amplitude, voltage, power and power spectral density are derived. Then, vibration characteristic, voltage, power and power SD with different load resistance, …sinusoidal acceleration and random acceleration SD are simulated and tested; moreover, frequency response function of MEMS piezoelectric energy harvester is obtained by experimental test, and the results are consistent with theoretical model. When sinusoidal acceleration is 0.6 g, the maximal amplitude of mass is 116 μm and the power density is 0.1 mW/cm^{3} . By testing results, output voltage of piezoelectric energy harvester is proportional to the amplitude, and the amplitude at optimal load is smaller than of at open circuit because of the feedback effect of load resistance. In addition, output power SD linearly increases with acceleration SD increasing. When acceleration SD is 5 × 10^{-4} (m/s^{2} )^{2} /Hz, power SD is 1.24 μW^{2} /Hz. Show more

Keywords: MEMS energy harvester, amplitude, random excitation, frequency response function

DOI: 10.3233/JAE-140002

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 125-139, 2015

Authors: El-Kharashi, Eyhab

Article Type: Research Article

Abstract: Most of the electrical machines designed to have their stators on the outside and their rotors on the inside. However, it was noticed that the shaft fills a relatively high volume inside the machine without producing any torque. That means there is a wasted volume within the machine and this volume does not produce any torque. From this point of view, there are some trends in designing and building electrical machines to have their rotors outside the …machine and their stators inside the machine. Here the example used for the machines using those designs is the permanent magnet (PM) machine, which is an electrical machines designed by the two different methods, inner and outer rotors to be used in many applications such as wind turbines and electric vehicle wheel motors. This paper is dedicated to prove that the external rotor permanent magnet machine is preferred for some significant reasons. The paper uses two approaches to demonstrate that. The first approach is using the geometrical volume of each machine to compare the torque capabilities in case of two possible topologies of the PM machines. The second approach is to compare the PM machine with another type of electrical machine, that has the same magnetic circuit topology and the rotor can be inside and outside as well. Show more

Keywords: Permanent magnets machine, outer rotor, inner rotor, geometric approach, segmented rotor

DOI: 10.3233/JAE-140003

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 141-152, 2015

Authors: Wang, Tao | Wang, Qingfeng

Article Type: Research Article

Abstract: Electro-hydraulic power units are key components of hybrid driven mobile machines such as forklifts and excavators. To satisfy the requirement of limited installation space, this paper proposes a compact and reversible electro-hydraulic energy conversion unit which is the integration of an axial piston hydraulic pump/motor and an electrical machine excited by a segmented Halbach permanent magnet array. The magnets are fixed on the surface of a barrel so that the hydraulic rotor and the electrical rotor …are integrated together. Analytical and numerical methods are used to investigate the coupling issues including the common rotor's effect on flux density distribution, combined torque ripple, flow and energy losses in the oil gap, and some design criteria are presented to provide further development with references. Show more

Keywords: Electro-hydraulic, structure integration, halbach array, energy conversion, coupling effect

DOI: 10.3233/JAE-140004

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 153-162, 2015

Authors: Singh, Ashish | Ansari, J.A. | Kamakshi, Dr. | Aneesh, Mohd. | Sayeed, Saiyed Salim

Article Type: Research Article

Abstract: In this article, analysis of slot loaded compact rectangular patch antennas have been presented theoretically using circuit theory concept. The theoretical investigations of L-strip fed slot loaded compact rectangular microstrip patch antenna parameters such as return loss, VSWR, radiation pattern have been calculated. It is found that antenna resonates at 2.95 GHz and 6.01 GHz for lower and upper resonance frequencies respectively. The bandwidth of the L-strip fed slot loaded compact rectangular microstrip patch …antenna at lower resonance frequency is 1.16% (simulated) and 10.16% (theoretical) whereas at upper resonance frequency, it is 1.5% (simulated) and 2.51% (theoretical). The characteristics of the L-strip fed slot loaded compact rectangular microstrip patch antennas is compared with other rectangular patch antennas. Circuit diagram of this antenna is proposed, fabricated and simulated using AWR circuit simulator. The theoretical results are compared with IE3D and AWR simulation results along with measured results and they are in close agreement. Show more

Keywords: Microstrip patch antenna, dualband, slot, L-strip, shorting pin

DOI: 10.3233/JAE-140020

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 163-175, 2015

Authors: Wang, Xiuchen | Liu, Zhe | Zhou, Zhong

Article Type: Research Article

Abstract: Though electromagnetic interference (EMI) shielding fabric with rectangular hole has wide application in various fields, there is not a mature approach to calculate its shielding effectiveness (SE) at present. This paper constructs a rapid computation model of the SE of the EMI shielding fabric with hole based on equivalent coefficient. Firstly, the rectangular hole characteristic is analyzed and a structure model of the rectangular hole under the consideration of the hole edge characteristic is described. The …equivalent relationship between the fabric hole and the standard hole is presented according to the equivalent theory. The rapid computation model of the SE of the EMI shielding fabric with hole is built including the equivalent coefficient and transmission coefficient according to the EMI shielding theory and the method to determine the equivalent coefficient is also given. Finally, the computation model is verified by experiments. The results show that the accuracy and the computational efficiency of the proposed model are good, and the model can be applied to the fabrics with wide weaves and various rectangular hole sizes. Show more

Keywords: Hole, electromagnetic interference shielding fabric, shielding effectiveness, computation model

DOI: 10.3233/JAE-140023

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 177-185, 2015

Authors: Jung, Kwang Suk

Article Type: Research Article

Abstract: An axial magnet wheel, in which permanent magnets are arranged circumferentially and polarized periodically, is proposed as a driving method to transfer a conductive rod without mechanical contact in space. The magnet wheel, whose axial plane is laid parallel to the rod, is rotated to generate three axial magnetic forces on the rod. But, the all forces are strongly coupled to each other through the rotational speed of the wheel. Furthermore, the number of degrees of …freedom to be controlled in the transfer system, in which the rod is supported by two pairs of magnet wheels actuated by two wheel motors, is more than the number of input variables. To solve the above problem, a novel method in which the transfer control of the rod is converted to a tilt control of the rod is proposed and verified experimentally. And, the force characteristic of the magnet wheel is analyzed for variations of the main geometric parameters to obtain the desired design specifications. Show more

Keywords: Conductive rod, electrodynamic force, independent control, magnet wheel, noncontact conveyance

DOI: 10.3233/JAE-140026

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 187-197, 2015

Authors: Liao, Yaoyao | Lian, Zisheng | Long, Risheng | Yuan, Hongbing

Article Type: Research Article

Abstract: The large flow electro-hydraulic directional valves are the key operating components for automation of the hydraulic roof supports in the coal mine. Cracking is a common failure mode of the valve. Effects of the buffer damp diameter, the valve type and the static pressure on the stress of the valve were researched. The valve dynamic behavior was investigated by AMESim. The transient collision stresses of the inlet valve sleeve of the main control valve under different …buffer damp diameters and different valve types were investigated by ANSYS/LS-DYNA. The static stress analysis was conducted in ANSYS too. Results show that the valve failure is due to the fatigue of the inlet valve sleeve when suffered from the collision stress wave in the valve opening process, rather than the lack of component strength. The buffer damp diameter, the key parameter of the valve, has a significant effect on the collision stress of the inlet valve sleeve. The integrated type valve has a better stress state compared to the separated type valve. This paper provides an effective method to solve the fracture problems of hydraulic directional valves. It is also significant for the design and optimization of hydraulic components. Show more

Keywords: Electro-hydraulic directional valve, stress analysis, fatigue, collision, hydraulic roof support

DOI: 10.3233/JAE-140028

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 199-209, 2015

Authors: Lin, Chih-Hong

Article Type: Research Article

Abstract: Due to V-belt continuously variable transmission (CVT) driven electric scooter with unknown nonlinear and time-vary characteristics, an accurately dynamic modeling of V-belt CVT driven electric scooter is the time-consuming procedure for the linear controller design. A hybrid modified recurrent Legendre neural network (NN) control system is proposed to control the V-belt CVT driven electric scooter under the occurrence of nonlinear load disturbances with parametric variations in order to acquire good control performance. …Firstly, system structure of the V-belt CVT driven electric scooter by using a permanent magnet synchronous motor (PMSM) servo drive system is proposed in this study. Secondly, the hybrid modified recurrent Legendre NN control system, which consists of an inspector control, a modified recurrent Legendre NN control with adaptive law and a recouped control with estimated law, is proposed to control the V-belt CVT driven electric scooter by using PMSM servo drive. Moreover, the on-line parameters tuning methodology of the modified recurrent Legendre NN is derived according to Lyapunov stability theorem and gradient descent method. Furthermore, two optimal learning rates of the parameters in the modified recurrent Legendre NN are developed to speedup convergence. Finally, to show the effectiveness of the proposed control scheme, comparative studies are demonstrated by simulated and experimental results. Show more

Keywords: Continuously variable transmission, electric scooter, permanent magnet synchronous motor, modified recurrent legendre neural network, lyapunov stability

DOI: 10.3233/JAE-140035

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 211-235, 2015

Authors: Ashraf, Faheem | Ahmed, Shakeel | Syed, A.A. | Naqvi, Q.A.

Article Type: Research Article

Abstract: We study the scattering of time harmonic electromagnetic plane wave from a topological insulator circular cylinder in chiral medium. Variation of scattering behavior for different values of radii and permittivity of the cylinder is noted when time reversal symmetry is protected and we also studied the scattering behavior when time reversal symmetry is broken. Although scattering behavior of co-polarized component of field is not significantly different from chiral cylinder in chiral medium yet it is found …that the same, when time reversal symmetry broken, is similar to scattering from a perfect conductors. Scattering behaviour of cross-polarized field component of topological cylinder in chiral medium is remarkably different from chiral cylinder i.e. it has stronger scattering possibly due to the presence of conducting states near the surface. Moreover, it is noted that the scattering in forward direction for cross-polarized and co-polarized components are not correlated with permittivity but for carefully selected values of permittivity, we can control the scattering behavior of topological insulator circular cylinder. Show more

Keywords: Topological insulator, chiral medium, circuar cylinder, time reversal symmetry, time harmonic electromagnetic waves, scattering

DOI: 10.3233/JAE-140039

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 237-244, 2015

Authors: Jiang, Shunong | Du, Jinlong

Article Type: Research Article

Abstract: Attached masses are utilized in this work to improve the performance of circular cylindrical piezoelectric transformers operating in thickness-shear mode. An exact solution based on the linear theory of piezoelectricity is obtained to verify the concept. The transforming ratio, displacement and stress fields of the transformer are investigated. Numerical results based on the theoretical analysis show the noticeable influences of the attached masses on the behavior of the transformer. The desirable load impedance for a high …transforming ratio is also obtained in this study. Show more

Keywords: Piezoelectric transformer, thickness-shear mode, transforming ratio

DOI: 10.3233/JAE-140043

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 245-253, 2015

Authors: Xu, Chunhua | Deng, Zhengdong | Xiong, Run | Deng, Feifan

Article Type: Research Article

Abstract: When using sub-cell algorithms to model the coupling of apertures with finite depth in the finite-difference time-domain (FDTD) method, time-step size is required to be reduced to avoid instability. In this work, a time-step program is proposed for the stable modeling of apertures with finite depth using sub-cell algorithms. A sub-cell area related time-step reduction coefficient is introduced to ease the steady reduction of the time-step size firstly. Then a modified algorithm is given for sub-cells …whose area is extremely distorted. Numerical results demonstrate that the proposed time-step program is an accurate and stable modeling of aperture coupling without resulting in significant time-step reduction. Show more

Keywords: Aperture coupling, FDTD method, stability, time-step program

DOI: 10.3233/JAE-140047

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 255-262, 2015

Authors: Kumar, Jitendra | Gupta, Navneet

Article Type: Research Article

Abstract: In this paper, a theoretical and practical investigation on microwave dielectric materials for wideband dielectric resonator antennas (DRAs) is presented. Due to the variety of materials available to antenna designers, a proper technique to select the best possible material is required. In this paper Ashby's material selection methodology is used for dielectric material based antenna systems. Four primary performance indices, impedance bandwidth (BW), the size of the antenna (λ), radiation efficiency (η) …and resonance frequency (f_{0} ), are used to obtain the desired performance. The selection chart shows that Roger TMM10, (ε_{r} = 9.8) is the most suitable material followed by "Roger's TMM10i and RO3010" for DRAs to provide the best performance for wideband applications. Performances of antenna are verified with rectangular and hybrid design of DRA in terms of reflection coefficients, radiation pattern, gain and efficiency. Theoretical work is compared with the simulation and the close agreement between the two, confirm the validity of this study. Show more

Keywords: Ashby's methodology, material selection, dielectric materials, wideband, dielectric resonator antenna, wireless communication

DOI: 10.3233/JAE-140051

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 263-272, 2015

Authors: Xi, Neng | Yang, Jia-Jun

Article Type: Research Article

Abstract: The severe drawback of slotted permanent magnet linear synchronous motor (PMLSM) is the detent force, particularly when accurate positioning and constant low speed is required for numerically controlled machine tool. In this paper, a novel short-armature slotted type multi-segment permanent magnet linear synchronous motor (MSPMLSM) is proposed and constructed to reduce the detent force. It consists of a proper shift of the multiple segments of iron core relative to the PMs. The detent forces of MSPMLSMs …with different number of segment are analyzed and simulated by finite element method (FEM). The proposed structure has been proved to be a very effective approach for the reduction of detent force. Then this paper presents the statistical and mathematical optimum design of a 3-segment PMLSM using response surface methodology (RSM) together with FEM to minimize the detent force. Full factorial design and steepest ascent method, one of the iterative search method, is proposed to establish optimal design area for applying RSM. Finally, the global optimal design is predicted and the optimally designed one is manufactured, and the numerical results and measured results are reported to validate the effectiveness of this proposed method. Show more

Keywords: Multi-segment permanent magnet linear synchronous motor, detent force, optimal design, response surface methodology, steepest ascent method

DOI: 10.3233/JAE-140069

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 273-282, 2015

Authors: Zhang, Qi | Zhou, Bihua | Yang, Bo | Wang, Jianbao

Article Type: Research Article

Abstract: By applying the Crank-Nicolson (CN) scheme to the divided two parts of Maxwell's equations, an efficiency-improved hybrid implicit-explicit finite-difference time-domain (HIE-FDTD) method is proposed to analyze the electromagnetic problems with fine-scale structure. Numerical formulations of the proposed HIE-FDTD algorithm for a 2D TE wave are analytically derived. The HIE-FDTD method, although conditionally stable, allows for larger time-step size than the conventional FDTD method. Moreover, the numerical performance of the proposed method is …verified to be quite good by comparing it against the existing HIE-FDTD method. Show more

Keywords: Finite-difference time-domain (FDTD) method, hybrid implicit-explicit FDTD (HIE-FDTD) method, leapfrog, stability condition

DOI: 10.3233/JAE-140118

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 47, no. 1, pp. 283-291, 2015