International Journal of Applied Electromagnetics and Mechanics - Volume 33, issue 1-2

Authors: He, W. | Luo, H.J. | Song, X.D. | Xu, Z.

Article Type: Research Article

Abstract: Magnetic induction tomography is considered to be valuable in medical application of testing brain edema. In this paper, we use the edge finite element method with electric field intensity E as the vector variable to simulate a multi-channel measuring system based on a real human brain finite element model. In simulation, we change the conductivity of brain edema and the frequency of exciting current to research the performance of the multi-channel measuring system in testing the …brain edema. Show more

Keywords: Magnetic induction tomography, edge finite element method, simulation

DOI: 10.3233/JAE-2010-1181

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 743-750, 2010

Authors: Demachi, Kazuyuki | Zhu, Haitao | Mizutani, Yurika

Article Type: Research Article

Abstract: The phase shift component of MRI image was simulated for the tumors including the ferromagnetic particles by DDS which yielded the magnetic field distortion around the tumors. The simulation clearly visualized the shape and position of tumors. This method can image selectively only the tumors including the ferromagnetic particles by DDS, and so will be useful for the early finding of small tumor that are difflcult to be found by coventional techniques.

Keywords: MRI, tumor detection, ferromagnetic particles, visualization

DOI: 10.3233/JAE-2010-1182

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 751-757, 2010

Authors: Xu, Zheng | Luo, Haijun | Wang, Junfeng | He, Wei

Article Type: Research Article

Abstract: A 4-layer concentric spherical model of human head was built to simulate the head EIT forward problem. The layers from outside to inside are scalp, skull, CFS (Cerebrospinal fluid) and brain tissue, respectively. A pair of point current sources placed on the outmost layer is regarded as the boundary condition, and an analytical method of separation of variables was employed to solve the problem. The electric potentials of different current injecting angles were calculated and the …equipotential lines were drawn. The simulation results revealed that, the increment of the brain tissue conductivity causes decrease of the magnitude of both real and imaginary parts of the electric potential on the scalp. The frequency property of the model was simulated, when the exciting frequency was increased, the imaginary part of the electric potential increased significantly. These analytical solutions could be used to analyze the head EIT problems and check the numerical solutions calculated from FEM or BEM. Show more

Keywords: Analytical solution, separation of variables, head EIT forward problem

DOI: 10.3233/JAE-2010-1183

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 759-768, 2010

Authors: Sun, Feng | Oka, Koich | Saibara, Yuuta

Article Type: Research Article

Abstract: This paper proposes a magnetic suspension system using a permanent magnet (PM) and a rotary actuator. In this suspension system, the suspension force is controlled by a variable magnetic flux path mechanism where the flux path is changed by varying the angle of the PM. The PM is magnetized in radial direction and driven by a rotary actuator. This system can change the magnetic polarity of the stator and generate a very small suspension force through …rotating the PM to some special angles. Since the fixed cores sustain the gravitational force of the suspended object and the rotary actuator has a larger reducer, this system also can generate a very big suspension force comparing with the input force. In this paper, first the prototype and the principle of this magnetic suspension system are explained. And in order to verify the proposed principle, the IEM (integral element method) analysis and basic experiments for magnetic flux density and attractive force are performed. The model is created, and the numerical simulation is carried out. Finally, suspension experiments are executed, and the results support our proposal. Show more

Keywords: Magnetic suspension, permanent magnet, rotary actuator, flux path control, IEM analysis

DOI: 10.3233/JAE-2010-1184

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 769-776, 2010

Authors: Du, Yumei | Jin, Nengqiang | Shi, Liming

Article Type: Research Article

Abstract: A controlled-PM Maglev system with permanent magnets and electromagnets excitation together can improve the lift/weight ratios, and reduce electromagnetic power consumption at the same air gap compared with a conventional electromagnetic attractive levitation system. It has been proved to be a very effective approach with great potential for application in magnetic levitation system. This paper analyses the magnetic force characteristics of linear synchronous motor in a controlled-PM maglev model vehicle system in …our lab with finite element method (FEM), presents the relationship between the magnetic forces and air gap at different current excitation, thrust-angle performance, and experiment results. Show more

Keywords: Linear synchronous motors, controlled-PM Maglev, hybrid maglev, magnetic force, FEM

DOI: 10.3233/JAE-2010-1185

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 777-784, 2010

Authors: Yamane, Ryuichiro | Kinoshita, Tetsuya | Park, Myeong-Kwan

Article Type: Research Article

Abstract: Magnetic levitation of molten metal can be simulated even in weak magnetic field by use of magnetic fluid as a surrounding fluid. The levitated liquid column is desirable to be stable, but it can be deformed or displaced from the equilibrium position. In the present research the disturbance is magnetically given to the liquid column and the excited oscillation is studied experimentally and analytically. The liquid column has inherent natural frequencies, and a kind of resonance …occurs at these frequencies, which will lead to the instability. Show more

Keywords: Magnetic fluid, levitation, instability

DOI: 10.3233/JAE-2010-1186

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 785-789, 2010

Authors: Tian, Yongsheng | Sun, Yanhua | Yu, Lie

Article Type: Research Article

Abstract: In magnetic thrust bearings (MTBs), eddy currents induced in the solid stator and thrust disk not only result in performance degrading of the bearing, but also influence the SRC of the coil when driven by a switching power amplifier. In this paper, a fractional differential equation (FDE) model of the SRC considering the effects of eddy current is proposed and a numerical solution can be obtained from it by a predictor-corrector algorithm. Results from finite element …method (FEM) and experiments show its validity. The presented model can be applied to the studies of self-sensing of non-laminated magnetic bearings. Show more

Keywords: Switching ripple current, fractional differential equation, FEM, magnetic bearing

DOI: 10.3233/JAE-2010-1187

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 791-799, 2010

Authors: Fan, Huiqing | Yang, Weiwei | Li, Chuang

Article Type: Research Article

Abstract: Electric and magnetic resonances of split-ring resonators (SRRs) as left-hand materials (LHM) were studied in a free space. Different copper thicknesses were designed to tune the electromagnetic resonance frequencies of SRRs. While the split gap width was varied, double-negative responses in SRRs were investigated in detail. Even both electric and magnetic resonance frequencies became higher as copper thickness was decreased, the electric resonance frequency increased much more higher with the increasing of the split …gap width. Show more

Keywords: Split-ring resonator, electric and magnetic resonant frequencies, gap width, copper thickness, left-handed materials

DOI: 10.3233/JAE-2010-1188

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 801-806, 2010

Authors: Choi, Jae-Hak | Chun, Yon-Do | Han, Pil-Wan | Koo, Dae-Hyun | Im, Jong-Bin | Lee, Ju

Article Type: Research Article

Abstract: This paper deals with the design of the structure and shape of writing probes in alternative electric data storage devices based on electric polarization fields. In order to design high recording density electric recording devices, the shape of the writing probe is optimized using a response surface methodology. The structure of a writing probe is also investigated according to the existence and nonexistence of the electric shield. The static and dynamic characteristic of recording density is …analyzed and compared with conventional recording devices based on the magnetic magnetization field. Show more

Keywords: Electric data recording, writing probe, response surface method, recording device

DOI: 10.3233/JAE-2010-1189

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 807-814, 2010

Authors: Luo, Jinglin | Yang, Baokun | Dong, Longlei

Article Type: Research Article

Abstract: Magneto-rheological (MR) damper is a smart damping device that can vary its damp with the change of magnetic field. Because of MR damper's exceptional characteristic, it has been widely used in many engineering fields, such as vehicle semi-active suspension control, seismic response reduction, weapon system, and so on. It is no doubt that the key to MR damper is magnetic circuit design. In this paper, a magnetic circuit design for a new structure MR damper (also …named as parallel-disks MR damper) is proposed, and the selection of materials, the calculation of coil turns and coil current is discussed. Finally, the design is analyzed with finite element method, and its effectiveness is verified. Show more

Keywords: Magnetic circuit design, parallel-disks MR damper, finite element analysis

DOI: 10.3233/JAE-2010-1190

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 33, no. 1-2, pp. 815-822, 2010