Analysis Of Electromagnetic Characteristics Research Articles

Wideband electromagnetic characteristics modeling and analysis of missile targets in ballistic midcourse

The wideband electromagnetic characteristics of missile targets in midcourse are the foundation of midcourse attack-defense confrontation. This paper proposes a novel electromagnetic scattering modeling method for midcourse targets based on a precise scattering center model, in which the nonideal scattering phenomenon, shielding effect and micro-motion are taken into consideration for the first time. Firstly, a precise scattering center model incorporating both the sliding scattering and anisotropic scattering is established. Then the change rule of the target attitude is generalized, and a checking method of the scattering center shielding effect is proposed for rotationally symmetric targets. Afterwards, a novel dynamic electromagnetic scattering model is presented, where the scattering center model updates along with the variation of the target attitude and can characterize the change of the electromagnetic characteristics of midcourse targets exactly. Finally, in light of the established model, the dynamic electromagnetic characteristics within different attitude angle bounds are analyzed by stages, and some useful conclusions are obtained. Experiment results from the measured data in anechoic chamber verify the validity of the proposed modeling method and relevant analysis.

Characteristic analysis and comparison of axial flux machines according to magnetization pattern for 500 W-class wind power generator application

This paper presents the electromagnetic characteristic analysis of axial flux machines applied to 500(W) class wind power generators. For the dramatic analysis time reduction, analytical method is applied, and comparative analysis is performed according to magnetization patterns of permanent magnets. Due to their structural features, quasi 3-dimensional analysis is employed, and correction function is introduced to consider the flux leakage of the machines. The analysis results are compared with the results by finite element method and experiment to validate the suggested method performed in this paper showing high reliability.

Electromagnetic Design Study of Transverse Flux Enhanced Type Superconducting Wind Turbine Generators

Transverse flux enhanced type superconducting synchronous machines have been studied for large-capacity wind power generation. The generators have multiple circular superconducting field coils in the rotor and copper armature windings in the stator. A parametric design study and electromagnetic characteristic analysis of the superconducting wind turbine generators (WTGs) have been carried out. The target output is 10 MW for a rotational speed of 10 rpm, and the diameter of the whole coil system is 5 m. Superconducting technology is quite effective for compact and lightweight design of large power capacity, low-speed and high torque generators. Armature and field coil dimensions and the number of poles are key parameters in the design study. FEM analysis was carried out to obtain magnetic flux density, magnetic flux linkage, induced voltage, fundamental generator characteristics, etc. Required superconducting wire length was also estimated.

Analysis of electromagnetic characteristics exhibited by high-power traveling-wave tubes based on a chain of coupled resonators beyond the boundary of the passband of the slow-wave system

The electrodynamic characteristics of a traveling-wave tube (TWT) are numerically and experimentally analyzed beyond the boundary of the transparency band. A high-power three-section TWT with a slow-wave system in the form of a chain of coupled resonators is used as an example to show that, at the low-frequency edge of the operating band, the loaded Q factor of the resonance corresponding to the π-mode oscillations is reduced and that the frequency characteristics do not shift into the low-frequency region.

"Organic" MgB2−xCx superconductor with high performance enabled by liquid mixing approach

Comparative analysis of structural and electromagnetic characteristics have been performed on nano SiC- and polycarbosilane-doped MgB2 samples prepared by the dry and liquid mixing approaches. The total benefit of liquid mixing approach for fabrication of "organic" MgB2 superconductor with excellent electromagnetic performance has been demonstrated.

An FDTD combined with semi-analytical recursive convolution algorithm for the analysis of general dispersive media

A novel finite-difference time-domain （FDTD） method combined with the semi-analytical recursive convolution （SARC） algorithm in DSP techniques for the analysis of electromagnetic characteristics in dispersive media is presented. In this method, the flexibility of FDTD in dealing with complicated objects is retained, while the advantages of absolute stability, high accuracy, low storage and high effectiveness of SARC in treating the linear system problem is introduced. The proposed SARC FDTD approach can therefore be applied to the analysis of general dispersive media provided the poles and corresponding coefficients in the dispersive medium model of interest are given. Three typical kinds of dispersive model, i.e. Debye, Drude and Lorentz medium are tested to demonstrate the feasibility of the present scheme.

High‐Resolution Signal‐Averaged Analysis of Atrial Electromagnetic Characteristics in Patients with Paroxysmal Lone Atrial Fibrillation

Abnormalities in the electromagnetic signal of the atria during sinus rhythm could serve as markers of triggering foci or substrate for atrial fibrillation (AF). We examined atrial electrophysiologic properties noninvasively by using magnetocardiographic mapping (MCG) in patients with paroxysmal lone AF to find whether any difference exists between those who have frequent triggers of AF and who don't. MCG was recorded over anterior chest during sinus rhythm in 80 patients with paroxysmal lone AF (44 +/- 12 years, 61 males) and 80 matched controls. Atrial wave duration (Pd) and root mean square amplitudes of the last 40 ms (RMS40) of the averaged filtered atrial complex were determined automatically. Patients expressing atrial arrhythmias triggering AF episodes were classified as focal AF. The Pd was 109 ms in patients and 104 ms in controls (P = 0.007). In focal AF (72%) the Pd was slightly prolonged and its proportion of the PR interval was larger, but RMS40 was normal compared to controls. In other patients, the Pd was close to controls, but the RMS40 was reduced (59 +/- 17 vs74 +/- 36 fT, P = 0.006). Pd and atrial RMS amplitudes were unrelated to duration of AF history or frequency of recurrences. Clinical subclasses of lone AF seem to possess distinct signal profiles of atrial depolarization. Differences in electrophysiological properties between these subclasses may reflect pathogenetic variation and could have implications on diagnostics and therapy.

Wentzel-Kramer-Brillouin and finite-difference time-domain analysis of Terahertz band electromagnetic characteristics of target coated with unmagnetized plasma

We investigate computationally the attenuation and reflection of Terahertz (THz) wave using targets coated with plasmas. The simulators are the Wentzel-Kramer-Brillouin (WKB) method and finite-difference time-domain (FDTD) method. The relation between the frequency of the incident electromagnetic (EM) wave and the attenuation caused by unmagnitized plasma is analyzed. The results demonstrate that the amount of absorbed power is a decreasing function of the EM wave frequency and the plasma collision frequency. For THz band incident wave, the attenuation that is caused by plasma is small when the plasma has common density and the collision frequency. This conclusion has fine applying foreground for plasma anti stealth.

Analysis of Electromagnetic Absorption and Scattering Characteristics of Conducting Elliptic Cylinder Coated with Absorber Film Using Conformal Mapping Method

Analysis of Electromagnetic Absorption and Scattering Characteristics of Conducting Elliptic Cylinder Coated with Absorber Film Using Conformal Mapping Method

Analysis of Electromagnetic Characteristics of a Grounded Slab and a Parallel-Plate Structure using the SDDI Technique

In this paper, the electromagnetic characteristics of a grounded slab and a parallel-plate structure are analyzed by the Spline-type Divided-Difference Interpolation (SDDI) technique. The technique efficiently evaluates the MoM impedance matrix elements of the multifold spectral or spatial domain integrals or summation in integrodifferential equations. The numerical results of the proposed method agree well with those of the corresponding literatures.

Three-dimensional structure of magnetic field in the mixed-μ levitation system using bulk superconductors

A permanent-magnet type mixed-/spl mu/ levitation system, which only needs an iron, permanent magnets and bulk superconductors, can realize an advantageous levitation system-for example, for transportation over a relatively long distance because of its simple structure and stable levitation without active control. A three-dimensional numerical analysis of electromagnetic force characteristics in the mixed-/spl mu/ levitation system is carried out and the results of the analysis are compared with experiments. From these results, the authors have confirmed that the three-dimensional structure of the magnetic field and the electromagnetic performance of superconductors strongly influence the characteristics of the electromagnetic force acting on the iron, which become unstable in some cases.

Electromagnetic Force Characteristics of Magnetic Gradient Levitation Systems using Bulk Superconductors

A superconducting magnetic gradient levitation system, which only needs an iron, bulk superconductors and permanent magnets or coils, can realize an interesting levitated transportation system over a relatively long distance because of its simple structure and stable levitation without active control. The system uses superconductors as a field shaping material to form magnetic gradient that can generate stable levitation force acting on the iron. In this paper, three-dimensional numerical analysis of electromagnetic force characteristics in the bulk superconducting magnetic levitation systems is carried out and the results of this analysis are compared with the experiment. From these results we have confirmed that the three-dimensional structure of the magnetic field and the electromagnetic performance of the superconductors strongly influence the characteristics of the electromagnetic force acting on the iron.

Proposal and FEM analysis of superconductive magnetic gradient levitation

A magnetic levitation system that enables a stable levitation even at a standstill without active control has been studied by numerical analysis of electromagnetic field. The new superconductive magnetic levitation system consists of superconducting coils and iron rails, and its principle of levitation is based on a magnetic gradient in space, which is obtained by the flux-conservation characteristic of superconducting coils. A two-dimensional FEM program was used for analysis of electromagnetic force characteristics in a two-dimensional plane and the distribution of coil current. These results show the two-dimensional stability of the system.

Waveguide diplexer and multiplexer design

A new computer-aided procedure of designing waveguide manifold multiplexers, which combines a rigorous numerical analysis of electromagnetic characteristics of the key elements of the structure and a simple circuit engineering design technique, is proposed. This procedure enables one to obtain the required multiplexer characteristics without any experimental corrections at the minimum computer time expense. Typical design results are given to demonstrate the efficiency of the method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>