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Mathematical Methods in Electromagnetic Theory, 2000. MMET 2000. International Conference on

Date 12-15 Sept. 2000

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  • 2000 International Conference on Mathematical Methods in Electromagnetic Theory [front matter]

    Page(s): 0_1 - 390
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    Freely Available from IEEE
  • Authors list

    Page(s): 715 - 719
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    Freely Available from IEEE
  • Dynamic node management and measure estimation in a state-driven fault injector

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    Validation of distributed systems using fault injection is difficult because of their inherent complexity, lack of a global clock, and lack of an easily accessible notion of a global state. To address these challenges, the Loki fault injector injects faults basled on a partial view of the global state of a distributed system, and performs a post-runtime analysis using an off-line clock synchronization algorithm to determine whether the faults were properly injected. In this paper, we first describe an enhanced runtime archietecture for the Loki fault injector and than present a new method for obtaining measures in Loki. The enhanced runtime allows dynamic entry and exit of nodes in the system. It also offers more efficient multicast of notification messages and more efficient communication between state machines on the same host, and is more scalable than the previous runtime. We than detail a new and flexible method for obtaining a wide range of performance and dependability measures in Loki. View full abstract»

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  • Low-grazing-angle scattering by a triangle model of an ocean wave

    Page(s): 417 - 419 vol.2
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    The boundary value problem (BVP) is reduced to a 1-D integral equation of the 1st kind and then to an ill-conditioned matrix equation. A new iterative method is proposed for such equations' solution, which produces a robust and adequate solution. This solution is compared with the genetic algorithm solution and good agreement is obtained. A strong backscattering for a 1° grazing angle is revealed from a resonant-sized foaming-like ocean wave, that is comparable in order with radar “sea-spikes” View full abstract»

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  • Reflection of a plane wave from a cylinder with fractal properties of the surface

    Page(s): 420 - 422 vol.2
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    The diffraction of a plane electromagnetic wave by a cylinder with fractal properties of the surface is investigated. The results of designing an integro-differential model of the conductive cylinder are represented on the basis of representations of the fractal geometry of a surface of actual scatterers. The obtained α-characteristics of the electromagnetic field has allowed generalization in the classical theory of diffraction of electromagnetic waves on conductive bodies View full abstract»

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  • Generalized analysis of a coaxial waveguide to radial waveguide junction

    Page(s): 500 - 502 vol.2
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    A new mathematical model of a coaxial waveguide to radial waveguide junction is presented. The solution has been obtained in terms of generalized scattering matrices. At first, closed form expressions for elements of a generalized admittance matrix of the junction have been derived. Then, the generalized admittance matrix has been converted to a generalized scattering matrix View full abstract»

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  • Aperture coupling in the bodies possessing a finite symmetry group

    Page(s): 423 - 425 vol.2
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    A numerical method for predicting the field penetrating an arbitrary opening in a symmetric body is considered. The method is based on the usage of coordinate functions of irreducible representations of the group {τN} of symmetries of the cavity. It enables one to reduce the calculation time by the factor ~N2 and to construct numerically an inverse operator for an arbitrary excitation function. The required machine memory is also reduced by the factor N View full abstract»

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  • Solution of lightning intensity distance distribution reconstruction problem by using the Schumann resonance signal

    Page(s): 589 - 591 vol.2
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    The inverse problem solution for revealing total worldwide lightning intensity and its distance distribution based on decomposition of average background Schumann resonance (SR) spectra is considered. The developed one-site technique can be applied without invoking any preliminary knowledge about spatial structure of the world thunderstorm activity. The technique allows a reduction of the influence of additive interference occurring in experimental measurements. Apart from average electric and magnetic field power spectra for the inverse problem solution it is suggested to use their linear combinations emphasizing the distance dependence and basic SR peaks. The influence of errors in source spectra and propagation parameters on recovered lightning intensity and its distance profile has been studied numerically View full abstract»

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  • Modeling and optimization of a new-type bandstop filter based on multiaperture irises

    Page(s): 503 - 505 vol.2
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    The general properties of the single- and double-band rejection sections based on the multiaperture irises have been investigated. A bandstop iris with two rejection resonances has been numerically investigated and measured. New type of three-section bandstop filter with three-slot irises has been designed, optimized and tested. The calculated results for an X-band bandstop filter have been confirmed with good accuracy in experiment View full abstract»

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  • Scattering of a plane electromagnetic wave by a metal-dielectric composite cylinder

    Page(s): 474 - 476 vol.2
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    The scattering of a plane electromagnetic wave by an infinite circular metal-dielectric cylinder (CMDC) is considered. The metal part of the cylinder is a sector of arbitrary angle of opening. One may use such structures in order to model the properties of a wedge-shaped load, which is frequently used in electromagnetic control applications. Since in some cases the analysis of the experimental data may be not reliable due to the small magnitude of the measured reflection coefficient and relative errors of the measurement equipment, there is a need for a closed-form analysis of the model structures. In the presented study the method of reexpansion in the basis functions at a given interval is used (Smirnov 1957; Shepilko 1979). The resulting field is presented in terms of the Bessel and Hankel functions. Applying the boundary condition to the Fourier series representation of the scattered field, the problem is reduced to the solution of a matrix equation with unknown expansion coefficients, which can be calculated with controlled accuracy. The scattered field is evaluated asymptotically and the backscattering radar cross section (BRCS) expression is derived. Accurate numerical results are presented in the case of E-polarized waves View full abstract»

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  • Electromagnetic wave scattering from an impedance plane covered with a dielectric layer

    Page(s): 462 - 464 vol.2
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    The problem of a plane wave scattering from an inhomogeneous periodic impedance plane, which is covered with a homogeneous layer of lossy dielectric, is solved in rigorous formulation. The solution is obtained in closed analytical form. The wave is scattered from a plane with non-specular reflecting reactance produced by the periodic groove structure. The grooves are filled with a low-loss dielectric and covered with a uniform dielectric layer View full abstract»

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  • Self and mutual admittance of waveguide system with an impedance flange

    Page(s): 491 - 493 vol.2
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    In this paper, the problem of radiation from finite array of identical waveguides with an impedance flange radiating in arbitrary stratified media has been solved. The problem can be reduced to a set of integral equations with respect to finite functions representing linear combinations of electric and magnetic fields tangential components on apertures of waveguides. The stationary functional is performed for these equations on the basis of variational principle. The expressions for the matching characteristics of the system (reflection and transmission coefficients of waveguides, self and mutual admittance) are obtained in the closed form by using the functional. The flange impedance influence on the matching characteristics of two rectangular apertures on the single mode assumption is numerically investigated View full abstract»

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  • Spectral approach to the synthesis of the waveguide bandstop filters based on dielectric rectangular posts

    Page(s): 479 - 481 vol.2
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    A nontraditional approach to the synthesis of waveguide rejection cells of a dielectric rectangular post type is developed on the basis of an exact solution of corresponding spectral problem taking into account the dielectric loss. The results of synthesis of the rejection cells and optimization of bandstop filters are presented View full abstract»

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  • Near-field effects in thermal radio emission

    Page(s): 592 - 594 vol.2
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    Our research is related with a new idea in the area of subsurface radiometry. This idea is based on a specific character of the quasi-stationary part of a thermal emission field (evanescent modes at interface). Until the present time this problem remained experimentally unsolved. The difficulty of these measurements is related to the strong influence of the media on antenna parameters, because the quasi-stationary field could be measured only at a small distance above the surface and only using electrically-small antennas (much less than the wavelength in a medium). The theoretical analysis shows that the effective depth of the formation of quasi-stationary component depends on the height of antenna above the surface of a medium and on the antenna size. At the surface, this skin-depth could be very small (for small antennas); it increases with the antenna height, and at the height comparable to wavelength in the medium it converges to skin-depth for the wave component of thermal emission. So, it is possible to discover the influence of the quasi-stationary field by measurements of the temperature-stratified medium using for the calibration the same medium at two different constant temperatures. Two near-field effects could be detected: (i) the effective radio brightness dependence on the height of the small antenna and (ii) radio brightness dependence on the aperture size at small distance above the surface. These effects lead to new one-wavelength methods of non-invasive temperature sounding of absorbing media, such as water and living tissue View full abstract»

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  • Scattering of electromagnetic waves by dielectric gratings with elliptically layered media

    Page(s): 569 - 571 vol.2
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    We have analyzed the scattering of electromagnetic waves by dielectric gratings with elliptically layered media using an improved Fourier series expansion method and a multilayer method. Numerical results are given for the transmitted scattered characteristics for the case of incident angle and frequency for both TM and TE waves. The influences of the incident angle and the frequency on the transmitted power are compared for circular cylinders and elliptic cylinders View full abstract»

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  • On the scheme for seeking the solution to a system of Maxwell's equations in a spherically symmetric model of the Earth-ionosphere waveguide

    Page(s): 644 - 646 vol.2
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    A classical scheme for solving the boundary-value problem for a system of Maxwell's equations in a spherically stratified model of the Earth-ionosphere waveguide has been known since the beginning of the 20th century, and implies the following. The elementary electric or magnetic dipoles are usually assumed as emitters. In each of these cases the Hertz potentials are introduced, which satisfy partial differential equations with separable variables. Solutions to this equations are sought either in the form of a series in terms of eigenfunctions of the angular operator or in the form of a series in terms of eigenfunctions of the radial operator. The transition from one series to the other is accomplished through the Watson transformation. Attempts to generalize this scheme to the case of more sophisticated waveguide and emitter models led the author to the conclusion that the scheme should be modified. To elucidate the essence of the problem, a very simple model is considered. Unlike the classical scheme, we abandoned the idea of introducing any potentials, and formulated boundary-value problems for the components of fields. The objective of this paper is to devise a reasonably rigorous mathematical scheme for seeking the formal expressions for solving a system of Maxwell's equations View full abstract»

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  • Problem of plane electromagnetic wave diffraction by multi-element grating embedded in a half-space

    Page(s): 563 - 565 vol.2
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    The problem of plane electromagnetic wave diffraction by a multi-element grating which is embedded in a half-space is considered. A system of singular integral equations is obtained by satisfying the necessary boundary conditions. The numerical results describing the resonance characteristics of the cascaded grating embedded in a half-space are presented in the paper View full abstract»

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  • The vortex lattice method in the electromagnetic wave diffraction on the method grading with gyrotropic layer

    Page(s): 578 - 580 vol.2
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    A mathematical model of diffraction of plane linear polarized monochromatic waves on the band grating located on one side of the planar gyrotropic layer is suggested. It is based on reducing the problem under consideration in its exact formulation to a singular integral equation and its numerical solution by the method of discrete singularities. This approach is interesting both for the possibility of discretization of the considered problem by the direct numerical method and the possibility of extending it to the corresponding problem with a multielement grating View full abstract»

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  • Modeling of elements with circular symmetry placed in a rectangular waveguide multiport

    Page(s): 482 - 484 vol.2
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    A set of algorithms based on matching the fields of a radial waveguide and several rectangular ones is described. The proposed approach can be applied to calculate both the multiports with tuning posts and the turnstile junctions with coaxial waveguides View full abstract»

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  • The scattering by a perfectly conducting paraboloid of rotation with an absorbing coating of the edges

    Page(s): 453 - 455 vol.2
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    The plane electromagnetic wave scattering by perfectly conducting paraboloid of rotation with toroidal absorbing coating of edge is considered. The calculation method is based on combination of the solution (in the near-field zone) of the model problem of the plane electromagnetic wave scattering by perfectly conducting wedge with absorbing cylinder on the edge and asymptotic high-frequency methods. Calculation results are presented View full abstract»

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  • Displays of possible harbigers of earthquakes on recordings of VLF-signals depending on their characteristics

    Page(s): 650 - 651 vol.2
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    A complex of electromagnetic disturbances precedes an earthquake. One of the methods of searching for seismoionospheric effects in the D-region is a radiograph of the Earth-ionosphere waveguide by VLF waves. Such research of of the parameters of the environment allows to obtain additional information about the physical mechanisms of electromagnetic precursors of earthquakes, and the solution of the given problem is directly connected to forecasting possible time intervals between the beginning of preparation and the moment of the earthquake. Records of VLF-signal amplitude show abnormal variations of different intensity above the seismically active region before and after strong earthquakes. The validity of the dependence between the registered disturbances and earthquakes can be experimentally proven either by a statistical method based on general regularities, or by the presence of special characteristics in the signal, inherent to the specific process with regard to the geophysical conditions as a whole View full abstract»

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  • Matching of the normally incident H-polarized plane wave with a layered half-space

    Page(s): 595 - 597 vol.2
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    The authors derive and compare a system of linear algebraic equations (SLAE) of the first or second kind. The data given in a table allows one to make conclusions about the accuracy of calculations as a function of SLAE order M, and the relative permittivity and thickness of the layered material View full abstract»

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  • Resonance effects for the diffraction by high reflecting gratings in the double resonances case

    Page(s): 572 - 574 vol.2
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    The authors present results which show a high efficiency for the modified perturbation method in the analysis of the resonance diffraction. In spite of the simplicity, they are in a very good agreement with existing experimental data. Moreover, the simplicity enables one to find the cases of special interest both for further experimental investigations and for solving the problem of high-accuracy measurements of gratings and media parameters, and for designing unique optical devices View full abstract»

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  • Solution of the direct and inverse problems of the wave reflection from the waveguide fragment filled with a lossy dielectric

    Page(s): 583 - 585 vol.2
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    Various math method applications for solving the transcendental equation system f1(a,b)-A=0, f2(a,b)-B=0. This system appears when a problem of determination of the complex permittivity from the known coefficient of reflection from the short ended rectangular waveguide fragment filled with a lossy dielectric is solved. Different types of the direct problem formulation which determine the variety of functions f1(a,b), f2(a,b) are considered. The comparison of the obtained results in dependence on the direct problem formulation is presented View full abstract»

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  • Photonic band gap structure created from artificial opals

    Page(s): 406 - 408 vol.2
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    The authors begin by discussing various characteristics of photonic band gap (PBG) materials. They go on to consider the special case of the 1D-PBG structures leading to 3D homogeneous periodic structures (for example, artificial opal) View full abstract»

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