An efficient method to calculate EM pulse dynamics in a wide nonuniform waveguide is proposed. Fourier transformation of the adiabatic approximation into time domain results in a series of traveling pulsed modes whose group velocities depend on the mode number, waveguide cross section and axis curvature. Parabolic equation can be used for numerical implementation of the asymptotic solution.
{"title":"Radio pulse propagation in a smoothly bent oversized waveguide","authors":"A. Popov","doi":"10.1109/DD.2003.238230","DOIUrl":"https://doi.org/10.1109/DD.2003.238230","url":null,"abstract":"An efficient method to calculate EM pulse dynamics in a wide nonuniform waveguide is proposed. Fourier transformation of the adiabatic approximation into time domain results in a series of traveling pulsed modes whose group velocities depend on the mode number, waveguide cross section and axis curvature. Parabolic equation can be used for numerical implementation of the asymptotic solution.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117082710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The famous Maliuzhinets explicit solution gives possibility to study surface waves propagating from the edge singularity of an impedance wedge. The problem of diffraction by a circular impedance cone can hardly be solved in an explicit form. Nevertheless, recent progress enables us to investigate the surface waves of the Rayleigh type and the conditions of their excitation in the vicinity of the impedance conical surface. We consider the excitation of the acoustic surface waves. The scalar surface waves exist in the vicinity of the surface provided the imaginary part of the impedance has the appropriate sign. We also study the Weyl-Van-der-Pol phenomenon in the scalar problem. This phenomenon implies interference of the surface waves with the spherical wave propagating from the vertex for sufficiently small value of the surface impedance.
{"title":"Acoustic surface waves of the Rayleigh type near an impedance cone","authors":"M. Lyalinov","doi":"10.1109/DD.2003.238227","DOIUrl":"https://doi.org/10.1109/DD.2003.238227","url":null,"abstract":"The famous Maliuzhinets explicit solution gives possibility to study surface waves propagating from the edge singularity of an impedance wedge. The problem of diffraction by a circular impedance cone can hardly be solved in an explicit form. Nevertheless, recent progress enables us to investigate the surface waves of the Rayleigh type and the conditions of their excitation in the vicinity of the impedance conical surface. We consider the excitation of the acoustic surface waves. The scalar surface waves exist in the vicinity of the surface provided the imaginary part of the impedance has the appropriate sign. We also study the Weyl-Van-der-Pol phenomenon in the scalar problem. This phenomenon implies interference of the surface waves with the spherical wave propagating from the vertex for sufficiently small value of the surface impedance.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114560898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper discusses a new near-field technique for temperature sounding of biological media. The special model of the biological-medium permittivity has been evolved in order to calculate its dependence upon temperature in a wide frequency range. An integral relation of measured antenna parameters to the subsurface temperature profile has been obtained, which is the basis for the inverse problem posing. Suitable parameters of the near-field measuring system have been determined.
{"title":"Application of near-field microwave sounding for subsurface thermometry of biological media","authors":"N. V. Yurasova, A. N. Reznik","doi":"10.1109/DD.2003.238287","DOIUrl":"https://doi.org/10.1109/DD.2003.238287","url":null,"abstract":"The paper discusses a new near-field technique for temperature sounding of biological media. The special model of the biological-medium permittivity has been evolved in order to calculate its dependence upon temperature in a wide frequency range. An integral relation of measured antenna parameters to the subsurface temperature profile has been obtained, which is the basis for the inverse problem posing. Suitable parameters of the near-field measuring system have been determined.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125638668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper discusses the methods of theory of generalized functions and the generalized solutions of the Maxwell equations that developed the boundary integral equations method for nonstationary boundary value problems of electrodynamics including shock electromagnetic waves. The unknown shallow currents complicates an algorithm of solving BIEs which gives the possibility to define a field of inwardly area.
{"title":"Boundary integral equations to time-dependent boundary value problems of diffraction of electromagnetic waves","authors":"L. Alexeyeva","doi":"10.1109/DD.2003.238126","DOIUrl":"https://doi.org/10.1109/DD.2003.238126","url":null,"abstract":"This paper discusses the methods of theory of generalized functions and the generalized solutions of the Maxwell equations that developed the boundary integral equations method for nonstationary boundary value problems of electrodynamics including shock electromagnetic waves. The unknown shallow currents complicates an algorithm of solving BIEs which gives the possibility to define a field of inwardly area.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132177664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper deals with some autonomous systems (ASs) of nonlinear ordinary differential equations (ODEs) arising from incompressible fluid mechanics. For these systems defined on a (semi)infinite interval and having in a phase space an infinite set of pseudohyperbolic equilibrium points, we discuss an approach to correct statement of singular boundary value problems (BVPs) and their reduction to equivalent regular ones. The associated stable numerical methods are proposed and the results of their application are illustrated.
{"title":"On correct statement of singular BVPs for autonomous systems of nonlinear ODEs with the applications to hydrodynamics","authors":"N. Konyukhova, A. I. Sukov","doi":"10.1109/DD.2003.238181","DOIUrl":"https://doi.org/10.1109/DD.2003.238181","url":null,"abstract":"This paper deals with some autonomous systems (ASs) of nonlinear ordinary differential equations (ODEs) arising from incompressible fluid mechanics. For these systems defined on a (semi)infinite interval and having in a phase space an infinite set of pseudohyperbolic equilibrium points, we discuss an approach to correct statement of singular boundary value problems (BVPs) and their reduction to equivalent regular ones. The associated stable numerical methods are proposed and the results of their application are illustrated.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"46 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133753417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we propose the application of the steepest descent method augmented with the optimal control theory approach, in order to solve the problem of fitting phenomenological parameters in coupled nonlinear reaction-diffusion equations, which parameters do not vary in time. The penalty function and two different transformations of the inequality constraints given are considered. The necessary optimality conditions are derived using the stationary condition of the Lagrangian, and a new numerical algorithm is designed. Results for computation of the heat conduction coefficient as well as a set of parameters in a mathematical biology problem are presented.
{"title":"Optimal steepest descent algorithm for experimental data fitting in nonlinear problems","authors":"K.N. Kozlov, A. Samsonov","doi":"10.1109/DD.2003.238182","DOIUrl":"https://doi.org/10.1109/DD.2003.238182","url":null,"abstract":"In this paper, we propose the application of the steepest descent method augmented with the optimal control theory approach, in order to solve the problem of fitting phenomenological parameters in coupled nonlinear reaction-diffusion equations, which parameters do not vary in time. The penalty function and two different transformations of the inequality constraints given are considered. The necessary optimality conditions are derived using the stationary condition of the Lagrangian, and a new numerical algorithm is designed. Results for computation of the heat conduction coefficient as well as a set of parameters in a mathematical biology problem are presented.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126307726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Major methods that were recently used for solving the electromagnetic field in the urban environment based on approximation methods named GTD,UTD,GO. With attention that these methods are obtained from the Maxwell equations by using the approximation and asymptotic methods, for many applications validity of them is limited. Although these models have variation about wavelength of field but this variation of field is not same as real field variation. Recently mobile systems have become smaller and smaller, and on the other hand must have excellent accuracy. Therefore it is necessary that better methods are used. With generalize the methods are used for field calculation in front of antennas and extended apertures this is possible to reach more accurate models.
{"title":"A new model for calculating diffraction fields, in urban environments, using physical optics approach","authors":"E. Torabi, A. Ghorbani","doi":"10.1109/DD.2003.238235","DOIUrl":"https://doi.org/10.1109/DD.2003.238235","url":null,"abstract":"Major methods that were recently used for solving the electromagnetic field in the urban environment based on approximation methods named GTD,UTD,GO. With attention that these methods are obtained from the Maxwell equations by using the approximation and asymptotic methods, for many applications validity of them is limited. Although these models have variation about wavelength of field but this variation of field is not same as real field variation. Recently mobile systems have become smaller and smaller, and on the other hand must have excellent accuracy. Therefore it is necessary that better methods are used. With generalize the methods are used for field calculation in front of antennas and extended apertures this is possible to reach more accurate models.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123671855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The linear stage of parametric instability of low-frequency surface waves guided by the planar metal-magnetoionic medium interface which can arise due to the presence of an intense electric field is investigated. It is assumed that superimposed static magnetic field is oriented parallel to the interface and to be aligned with the propagation direction of the surface waves. The influence of the dielectric slab between the metal and magneto-ionic medium are discussed.
{"title":"Nonlinear interaction of surface waves guided by the metal-anisotropic medium interface","authors":"N. F. Yashina, T. Zaboronkova","doi":"10.1109/DD.2003.238286","DOIUrl":"https://doi.org/10.1109/DD.2003.238286","url":null,"abstract":"The linear stage of parametric instability of low-frequency surface waves guided by the planar metal-magnetoionic medium interface which can arise due to the presence of an intense electric field is investigated. It is assumed that superimposed static magnetic field is oriented parallel to the interface and to be aligned with the propagation direction of the surface waves. The influence of the dielectric slab between the metal and magneto-ionic medium are discussed.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"151 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122897234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For the oscillator-like systems, connected with q-Hermite polynomials, coherent states of Barut-Girardello type are defined. The well-known Arik-Coon oscillator naturally arose in the framework of suggested approach as oscillator, connected with the Rogers q-Hermite polynomials, in the same way as usual oscillator with standard Hermite polynomials. The results about the coherent states for discrete q-Hermite polynomials of II type are quite new.
{"title":"Generalized coherent states for q-oscillator connected with q-Hermite polynomials","authors":"V. Borzov","doi":"10.1109/DD.2003.238130","DOIUrl":"https://doi.org/10.1109/DD.2003.238130","url":null,"abstract":"For the oscillator-like systems, connected with q-Hermite polynomials, coherent states of Barut-Girardello type are defined. The well-known Arik-Coon oscillator naturally arose in the framework of suggested approach as oscillator, connected with the Rogers q-Hermite polynomials, in the same way as usual oscillator with standard Hermite polynomials. The results about the coherent states for discrete q-Hermite polynomials of II type are quite new.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115327548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we consider a nonstationary scattering of plane waves by a wedge. We prove uniqueness of solution to the Cauchy problem in appropriate functional spaces and we give the Sommerfeld-type representation of solution developing method of complex characteristics.
{"title":"Well-posedness of the problem of nonstationary diffraction of Sommerfeld on a wedge uniqueness","authors":"A. Merzon","doi":"10.1109/DD.2003.238228","DOIUrl":"https://doi.org/10.1109/DD.2003.238228","url":null,"abstract":"In this paper, we consider a nonstationary scattering of plane waves by a wedge. We prove uniqueness of solution to the Cauchy problem in appropriate functional spaces and we give the Sommerfeld-type representation of solution developing method of complex characteristics.","PeriodicalId":332604,"journal":{"name":"International Seminar Day on Diffraction, 2003. Proceedings.","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2003-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124903458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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