International Journal of Applied Electromagnetics and Mechanics - Volume 40, issue 2

Authors: Tang, Enling | Zhang, Qingming | Xiang, Shenghai | Yang, Minghai | Liu, Fusheng | Zhang, Mingjian

Article Type: Research Article

Abstract: In order to diagnose electromagnetic properties and light flash characteristics generated by hypervelocity impact, the diagnostic systems of sweep Langmuir probe(SLP) and triple Langmuir probe (TLP) for electron temperature and electron density in plasma were established, properties of magnetic field were obtained by using coil measurement system established, and characteristics of light flash were also acquired through optical pyrometer measurement system during the whole physical process in hypervelocity impact, Experimental results …showed that the average electron temperature of the triple Langmuir probe was near 0.75 eV on the whole physical process, the average electron density in the experiment was about. However, the electron temperature and electron density of plasma acquired by using t he sweep Langmuir probe were lower than the values by using triple Langmuir probe. The peak value of magnetic induction intensity induced by plasma was 9.8 × 10^{11} /cm^3 during the hypervelocity impacts, and light flash intensity peak value was 40–50 mW.cm^{-2} .nm^{-1} in the experimental conditions in the paper. Show more

Keywords: Hypervelocity impacts, plasma, electromagnetic properties, impact light flash

DOI: 10.3233/JAE-2012-1431

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 2, pp. 85-99, 2012

Authors: Zhang, Hongxin | Zhang, Jinling | Wang, Danzhi | Lu, Yinghua

Article Type: Research Article

Abstract: To quantitatively evaluate the strength of information leakage arising from computer under shielding conditions, a mathematic model is established for information leakage based on near-field measurement results by using the equivalence principle. In order to study the leakage threshold and the shielding performance for information leakage, the notions of Information Identifying Degree, Information Resolution Threshold and Computer Security Defence Distance are formalized respectively. Then, Information Identifying Degree, Information Resolution Threshold and Computer …Security Defence Distance are analyzed. So, the strength of information leakage is quantitatively assessed under different shielding levels and distance. The simulation results show that FCC and MIL461C standards are not suitable for the evaluation of information leakage and even strictly standard should be considered. At last, new shielding levels of information leakage are marked off and the shielding effects are assessed by using Information Resolution Threshold. This research aptly provides a quantitative evaluation method for assessing the information leakage strength and presents a means to evaluate information leakage shielding effectiveness of computers. Show more

Keywords: Electromagnetic emission, information leakage, information security

DOI: 10.3233/JAE-2012-1432

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 2, pp. 101-111, 2012

Authors: Chang, Chao | Gao, Cun-Fa | Shi, Yan

Article Type: Research Article

Abstract: The 2D problems of a soft ferromagnetic solid with collinear cracks are studied based on the complex variable method. First, the general solutions for potential functions of magnetic fields and stress fields are derived by using magnetically permeable, impermeable and conducting crack models, respectively. Then, for special cases of one and two cracks, more explicit solutions are given for potential functions and intensity factors of total stresses. Finally, numerical results are presented to discuss the effects …of applied magnetic loading on fracture behavior of the ferromagnetic solid. It is found that the total stresses always have the classical singularity of the r^{ - 1/2} type at the crack tips for the considered three crack models, and the applied magnetic loading may either enhance or retard crack growth depending on the adopted crack models. Show more

Keywords: Soft ferromagnetic solid, collinear cracks, maxwell stress, singularities

DOI: 10.3233/JAE-2012-1433

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 2, pp. 113-132, 2012

Authors: Díaz, Guillermo A. | Mombello, Enrique E. | Stephan, Voss

Article Type: Research Article

Abstract: With the aim of introducing a computationally efficient solution for problems such as the fast computation of magnetic field magnitudes and forces in coils and windings, this paper presents analytical expressions for the magnetic vector potential and magnetic field intensity in radial and axial directions due to a finite cylinder with infinitesimal wall thickness carrying a linearly varying current density between the values at the lower and upper ends. All expressions have been derived in terms …of complete elliptic integrals of first, second and third kind, whose evaluation is achieved by means of very fast algorithms. The formulas presented make possible the fast computation of magnetic field at any point in space at reduced computational cost. The formulation is not only specially suited for modeling the current distribution in foil windings of power transformers but also for representing the magnetization of transformer core legs. The present method is also useful for efficient modeling of cylinders with constant current density since it is a generalization of this especial case. Finally, an example is presented where the results achieved using the proposed method are compared with those obtained using the finite element method showing a very good agreement between them. Show more

Keywords: Azimuthal current density, Biot-Savart law, elliptic integral, magnetic field

DOI: 10.3233/JAE-2012-1434

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 2, pp. 133-147, 2012

Authors: Zhang, Jingjun | Zhang, Haijun | Ding, Guangbin | Gao, Ruizhen | Long, Rong

Article Type: Research Article

Abstract: It is known that skewed rotor structure for electrical machines can reduce torque ripple and radial force which will produce the unwanted vibration and noise, however, utilizing this structure can also affect other parameters of machine such as the average torque, the inductance, the flux-linkage and the magnetic energy and so on. This drawback always shows in the special and popular machines-switched reluctance motors. In this paper, different skewed angles of rotor and their effects on …the key electromagnetic parameters are analyzed for switched reluctance motor. During the whole analysis process, three-dimensional finite element method is used to model, mesh, solve, and plot the results. Especially, the properties of the magnetic materials, the complex motor geometry, the effects of magnetic saturation and end windings were considered. Simulated and compared results show that an appropriate skewed angle selected can reduce the radial force largely but not make the average torque decreasing badly, which can be observed from the final conclusion: under the skewed angle of 5°, the radial force is reduced of 56.2%, the average torque is only reduced of 18.9%. So, if the target of designing for switched reluctance motors is to reduce the vibration and noise to be the most extent, then selecting an appropriate skewed structure for rotor shape is an effective way. Show more

Keywords: Switched reluctance motors, electromagnetic, skewed angle, FEM

DOI: 10.3233/JAE-2012-1581

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 2, pp. 149-163, 2012

Authors: Shao, Shan-Shan | Yang, Fuqian | Xuan, Fu-Zhen

Article Type: Research Article

Abstract: An analysis was made of the diffusional creep in polycrystalline materials when subjected to simultaneous action of tensile stress and electric current. Incorporating the contribution of electromigration to atomic diffusion in grain boundaries, the problem of grain boundary diffusion was solved. A simple relationship was derived between diffusional creep rate and local electric field intensity (current density). The results showed that electromigration can enhance the diffusional creep in polycrystalline materials.

Keywords: Electromigration, diffusion creep

DOI: 10.3233/JAE-2012-1583

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 40, no. 2, pp. 165-171, 2012