hig.sePublications
Change search

BETA
Shestopalov, Yury
##### Publications (10 of 120) Show all publications
Shestopalov, Y. (2019). A General Approach to the Analysis of Complex Waves. In: 2019 URSI International Symposium on Electromagnetic Theory (EMTS): . Paper presented at 2019 URSI International Symposium on Electromagnetic Theory (EMTS) (pp. 1-2).
Open this publication in new window or tab >>A General Approach to the Analysis of Complex Waves
2019 (English)In: 2019 URSI International Symposium on Electromagnetic Theory (EMTS), 2019, p. 1-2Conference paper, Published paper (Refereed)
##### Abstract [en]

We propose a technique for the search and calculation of complex waves in open and shielded circularly symmetric metal-dielectric waveguides with piecewise homogeneous filling by proving the existence and determination of the location of roots of the corresponding dispersion equations in the complex domain. The approach develops the method employing generalized cylindrical polynomials applied earlier to the rigorous analysis and determination of real waves.

Mathematics
##### Identifiers
urn:nbn:se:hig:diva-31338 (URN)10.23919/URSI-EMTS.2019.8931512 (DOI)2-s2.0-85077954457 (Scopus ID)978-1-946815-06-4 (ISBN)
##### Conference
2019 URSI International Symposium on Electromagnetic Theory (EMTS)
Available from: 2019-12-19 Created: 2019-12-19 Last updated: 2020-01-27Bibliographically approved
Smith, P. D., Vinogradova, E. D. & Shestopalov, Y. (2019). Accurate cutoff wavenumbers of a waveguide perturbed by axially aligned inner conductors. In: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA): . Paper presented at 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 9-13 September 2019, Granada, Spain (pp. 1049-1049).
Open this publication in new window or tab >>Accurate cutoff wavenumbers of a waveguide perturbed by axially aligned inner conductors
2019 (English)In: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2019, p. 1049-1049Conference paper, Published paper (Refereed)
##### Abstract [en]

Time-harmonic propagating modes in a perfectly electrically conducting waveguide with constant cross-section $\partial \mathrm{D}$ and axis aligned with the z-axis have the form $\mathrm{u}(\mathrm{x},\mathrm{y})\mathrm{e}^{-\mathrm{i}\omega \mathrm{t}-\mathrm{i}\gamma\mathrm{z}}$ where the cross-sectional function u satisfies the two-dimensional Helmholtz equation $(\Delta+\lambda)\mathrm{u}=0$; here $k$ denotes the wavenumber and $\lambda=\mathrm{k}^{2}-\gamma^{2}$. Propagating modes occur at values $\lambda_{1}\leq\lambda_{2}\leq\lambda_{3}\leq\cdots$ of $\lambda$ generating non-trivial solutions of the Helmholtz equation; the cutoff wavenumbers correspond to setting $\gamma$ to zero. Now suppose that axially aligned PEC structures of cross-section $\Gamma$ are inserted in the waveguide. The propagation constants are perturbed to values that may be denoted $\lambda_{1}+\Delta\lambda_{1},\lambda_{2}+\Delta\lambda_{2},\ldots$; the cutoff wavenumbers of the empty waveguide are correspondingly perturbed. In this paper we present a reliable, effective and efficient method to obtain the perturbed propagation constants. It allows us to examine the inclusion of multiple strips aligned with the z-axis, with the potential for characterizing propagation in structures with a number of small strip inserts, metamaterial-filled waveguides and so on.

##### Keywords
Mathematical model, Propagation constant, Strips, Cutoff frequency, Transmission line matrix methods, Conductors, Australia
##### National Category
Electrical Engineering, Electronic Engineering, Information Engineering
##### Identifiers
urn:nbn:se:hig:diva-30884 (URN)10.1109/ICEAA.2019.8879114 (DOI)2-s2.0-85074937469 (Scopus ID)978-1-7281-0563-5 (ISBN)
##### Conference
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 9-13 September 2019, Granada, Spain
Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2019-11-25Bibliographically approved
Shakhverdiev, A. K., Shestopalov, Y., Mandrik, I. E. & Arefiev, S. V. (2019). Alternative concept of monitoring and optimization water flooding of oil reservoirs in the conditions of instability of the displacement front. Neftânoe hozâjstvo, 2019(12), 118-123
Open this publication in new window or tab >>Alternative concept of monitoring and optimization water flooding of oil reservoirs in the conditions of instability of the displacement front
2019 (Russian)In: Neftânoe hozâjstvo, ISSN 0028-2448, Vol. 2019, no 12, p. 118-123Article in journal (Refereed) Published
##### Abstract [en]

It has always been an urgent issue for the oil and gas industry to improve oil, gas, and condensate recovery at liquid and gaseous hydrocarbon fields developed with the use of artificial formation pressure maintenance techniques that involve injection of water or water combined with other displacement agents. Therefore, due to the aforesaid issues, permanent attention should still be paid to the practical problem of optimizing the non-stationary hydrodynamic pressure applied to a reservoir by regulating the operating conditions of the production and injection wells, development process optimization in general, and water flooding in particular. The theory of Buckley and Leverett, does not take into account the loss of stability of the displacement front, which provokes a stepwise change and the triple value of water saturation. Traditionally a mathematically simplified approach was proposed-a repeatedly differentiable approximation to eliminate the “jump” in water saturation. Such a simplified solution led to negative consequences well-known from the water flooding practice, recognized by experts as “viscous instability of the displacement front” and “fractal geometry of displacement front”. The core of the issue is an attempt to predict the beginning of the stability loss of the front of oil displacement by water and to prevent its negative consequences on the water flooding process under difficult conditions of interaction of hydro-thermodynamics, capillary, molecular, inertial, and gravitational forces. In this study, catastrophe theory methods applied for the analysis of nonlinear polynomial dynamical systems are used as a novel approach. Namely, a mathematical growth model is developed and an inverse problem is formulated so that the initial coefficients of the system of differential equations for a two-phase flow can be deter mined using this model. A unified control parameter has been selected, which enables one to propose and validate a discriminant criterion for oil and water growth models for monitoring and optimizing.

##### Place, publisher, year, edition, pages
Neftyanoe Khozyaistvo, 2019
##### Keywords
Discriminant analysis, Filtration of multiphase fluids, Flooding system, Growth models, Regulation of well operation modes
##### National Category
Mechanical Engineering Earth and Related Environmental Sciences
##### Identifiers
urn:nbn:se:hig:diva-31402 (URN)10.24887/0028-2448-2019-12-118-123 (DOI)2-s2.0-85077384442 (Scopus ID)
Available from: 2020-01-13 Created: 2020-01-13 Last updated: 2020-01-13Bibliographically approved
Shestopalov, Y., Shakhverdiev, A., Mandrik, I. & Arefiev, S. (2019). Alternative conception of the monitoring and optimization of water flooding of oil reservoirs  under instability of displacement front. Oil industry (Neftyanoye khozyaystvo) (12), 118-123
Open this publication in new window or tab >>Alternative conception of the monitoring and optimization of water flooding of oil reservoirs  under instability of displacement front
2019 (Russian)In: Oil industry (Neftyanoye khozyaystvo), ISSN 0028-2448, no 12, p. 118-123Article in journal (Refereed) Published
##### Abstract [en]

The theory of Buckley and Leverett does not take into account the loss of stability of the displacement front whch provokes a stepwise change and the triple value of water saturation. Traditionally a mathematically simplified approach was proposed: a differentiable approximation to eliminate the ' jump' in water saturation. Such a simplified solution led to negative consequences well-know from the water flooding practice, recognized by experts as 'viscous instability of the displacement front' and 'fractal geometry of the displacement front'.The core of the issue is to attempt to predict the beginning of the stability loss of the front of oil displacement by water and to prevent its negative effect on the water flooding process under difficult conditions of interaction of hydro-thermodynamic, capillary, molecular, inertial, and gravitational forces. In this study, catastrophe theory methods applied for the analysis of nonlinear polynomial dynamical systems are used as a novel approach. namely, a mathematical growth model is developed and an inverse problem is formulated so that the initial coefficients of the system of differential equations for a two-phase flow can be determined using this model. A unified control parameter has been selected which enables one to propose and validate a discriminant criterion for  oil and water growth models for monitoring and optimization.

Moscow: , 2019
##### Keywords
Filtration of multi-phase fluids, water-flooding system, monitoring of oil well exploitation, growth models, discriminant analysis
##### National Category
Other Natural Sciences
##### Identifiers
urn:nbn:se:hig:diva-31339 (URN)
Available from: 2019-12-19 Created: 2019-12-19 Last updated: 2019-12-19Bibliographically approved
Cappello, B., Shestopalov, Y. & Matekovits, L. (2019). Analysis of the surface impedance of a sinusoidally modulated metasurface. In: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA): . Paper presented at 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 9-13 September 2019, Granada, Spain (pp. 0075-0077). IEEE
Open this publication in new window or tab >>Analysis of the surface impedance of a sinusoidally modulated metasurface
2019 (English)In: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), IEEE, 2019, p. 0075-0077Conference paper, Published paper (Refereed)
##### Abstract [en]

Metasurfaces have been extensively exploited in recent years for mantle cloaking applications. In this type of problems it is of fundamental importance to determine the connection between the metasurface geometrical parameters and the realised value of surface impedance, in order to properly design the metasurface. In this paper the surface impedance of a non homogeneous metasurface, based on a sinusoidally modulated metallic pattern is analysed.

IEEE, 2019
##### Keywords
Impedance, Surface impedance, Dielectrics, Surface waves, Harmonic analysis, Scattering, Cloaking, metamaterials, periodic structures
##### National Category
Electrical Engineering, Electronic Engineering, Information Engineering
##### Identifiers
urn:nbn:se:hig:diva-30885 (URN)10.1109/ICEAA.2019.8879149 (DOI)2-s2.0-85074934092 (Scopus ID)978-1-7281-0563-5 (ISBN)
##### Conference
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 9-13 September 2019, Granada, Spain
Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2019-11-25Bibliographically approved
Smirnov, Y., Smolkin, E. & Shestopalov, Y. (2019). Diffraction of a TE-Polarized Wave by a Nonlinear Goubau Line. Radio Science, 54(1), 151-157
Open this publication in new window or tab >>Diffraction of a TE-Polarized Wave by a Nonlinear Goubau Line
2019 (English)In: Radio Science, ISSN 0048-6604, E-ISSN 1944-799X, Vol. 54, no 1, p. 151-157Article in journal (Refereed) Published
##### Abstract [en]

The diffraction of a cylindrical wave by a nonlinear metal-dielectric waveguide filled with nonlinear medium is considered. Two widely used types of nonlinearities (Kerr nonlinearity and nonlinearity with saturation) are considered. The problem is to find amplitudes of the reflected and the transmitted fields when the amplitude of the incident field is known. The analytical and numerical solution techniques are developed. Numerical results are presented. ©2019. American Geophysical Union. All Rights Reserved.

##### Place, publisher, year, edition, pages
Blackwell Publishing Ltd, 2019
##### Keywords
nonlinear waveguide, numerical method, TE polarization, the diffraction problem, Dielectric waveguides, Numerical methods, Analytical and numerical solutions, Diffraction problem, Kerr nonlinearity, Nonlinear metals, Nonlinear waveguides, Numerical results, TE polarizations, Transmitted field, Diffraction
##### National Category
Mathematics Other Engineering and Technologies
##### Identifiers
urn:nbn:se:hig:diva-30478 (URN)10.1029/2018RS006629 (DOI)000458731300012 ()2-s2.0-85060646358 (Scopus ID)
Largescale
##### Funder
Swedish Institute
##### Note

Funding agencies:

- Ministry of Education and Science of the Russian Federation Grant no. 1.894.2017/4.6

- University of Gavle, Sweden

Available from: 2019-08-09 Created: 2019-08-09 Last updated: 2019-08-09Bibliographically approved
Khulbe, M., Tripathy, M. R., Parthasarathy, H., Shestopalov, Y. & Lagovsky, B. (2019). Inverse Scattering and Imaging Using Second Order Optical Nonlinearities. In: 2019 6th International Conference on Signal Processing and Integrated Networks, SPIN 2019: . Paper presented at 6th International Conference on Signal Processing and Integrated Networks, SPIN 2019, 7-8 March 2019, Noida, India (pp. 1086-1089). IEEE
Open this publication in new window or tab >>Inverse Scattering and Imaging Using Second Order Optical Nonlinearities
2019 (English)In: 2019 6th International Conference on Signal Processing and Integrated Networks, SPIN 2019, IEEE, 2019, p. 1086-1089Conference paper, Published paper (Refereed)
##### Abstract [en]

In this paper a mathematical technique is developed to find the parameters of a medium in terms of its scattered electromagnetic fields. Optical nonlinearity plays an important role in finding the scattering parameters of a medium. Using perturbation theory and nonlinear inverse scattering techniques with first order, second order and third order optical nonlinearity we find scattered electromagnetic fields. Using error minimization techniques parameters are estimated in term of permittivity and permeability up to second order. © 2019 IEEE.

IEEE, 2019
##### Keywords
Inverse scattering, least square estimation techniques, Optical nonlinearity, parameter extraction, permeability, permittivity, RF imaging, Electromagnetic fields, Electromagnetic wave diffraction, Mechanical permeability, Parameter estimation, Perturbation techniques, Signal processing, Least square estimation, Perturbation theory, Scattered electromagnetic fields, Second order optical nonlinearity, Third-order optical nonlinearities, Nonlinear optics
##### National Category
Signal Processing
##### Identifiers
urn:nbn:se:hig:diva-30501 (URN)10.1109/SPIN.2019.8711652 (DOI)000470844100209 ()2-s2.0-85066895033 (Scopus ID)9781728113791 (ISBN)
##### Conference
6th International Conference on Signal Processing and Integrated Networks, SPIN 2019, 7-8 March 2019, Noida, India
##### Note

Funding agency:

- DST, New Delhi INT/RUS/RFBR/P-341

Available from: 2019-08-15 Created: 2019-08-15 Last updated: 2019-08-22Bibliographically approved
Shestopalov, Y., Samokhin, A. & Samokhina, A. (2019). Iterative Gradient Descent Methods for Solving Linear Equations. Computational Mathematics and Mathematical Physics, 59(8), 1267-1274
Open this publication in new window or tab >>Iterative Gradient Descent Methods for Solving Linear Equations
2019 (English)In: Computational Mathematics and Mathematical Physics, ISSN 0965-5425, E-ISSN 1555-6662, Vol. 59, no 8, p. 1267-1274Article in journal (Refereed) Published
##### Abstract [en]

The paper presents the results on the use of gradient descent algorithms for constructing iterative methods for solving linear equations. A mathematically rigorous substantiation of the conver- gence of iterations to the solution of the equations is given. Numerical results demonstrating the effi- ciency of the modified iterative gradient descent method are presented.

##### Keywords
systems of linear algebraic equations, gradient descent, iterative methods
Mathematics
##### Identifiers
urn:nbn:se:hig:diva-30718 (URN)10.1134/S0965542519080141 (DOI)
Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2019-10-04Bibliographically approved
Shestopalov, Y. (2019). Justification of mathematical imaging technique for the permittivity determination of layered dielectrics in a waveguide. In: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA): . Paper presented at 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 9-13 September 2019, Granada, Spain (pp. 0143-0146).
Open this publication in new window or tab >>Justification of mathematical imaging technique for the permittivity determination of layered dielectrics in a waveguide
2019 (English)In: 2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 2019, p. 0143-0146Conference paper, Published paper (Refereed)
##### Abstract [en]

An introduction to mathematical imaging technique for solving inverse scattering problems is given. Applications are considered to inverse waveguide problems of recontructing permittivity of layered dielectric inclusions. The solution is justified of the inverse microwave imaging by establishing one-to-one correspondence between the sought quantities and the measured noisy data.

##### Keywords
Permittivity, Frequency measurement, Permittivity measurement, Noise measurement, Imaging, Dielectrics, Inverse problems, inverse scattering, waveguide, layer, dielectric
##### National Category
Electrical Engineering, Electronic Engineering, Information Engineering
##### Identifiers
urn:nbn:se:hig:diva-30886 (URN)10.1109/ICEAA.2019.8879417 (DOI)2-s2.0-85074948304 (Scopus ID)978-1-7281-0563-5 (ISBN)
##### Conference
2019 International Conference on Electromagnetics in Advanced Applications (ICEAA), 9-13 September 2019, Granada, Spain
Available from: 2019-11-05 Created: 2019-11-05 Last updated: 2019-11-25Bibliographically approved
Shestopalov, Y., Aboltins, A. & Litvinenko, A. (2019). Mathematical methods for inverse waveguide problems. In: 2019 IEEE Microwave Theory and Techniques in Wireless Communications  (MTTW). Proceedings: . Paper presented at 2019 IEEE Microwave Theory and Techniques in Wireless Communications (MTTW).
Open this publication in new window or tab >>Mathematical methods for inverse waveguide problems
2019 (English)In: 2019 IEEE Microwave Theory and Techniques in Wireless Communications  (MTTW). Proceedings, 2019Conference paper, Published paper (Refereed)
##### Abstract [en]

An introduction is given to mathematical methods for inverse waveguide  problems. Applications are considered to the solution of the inverse  waveguide problems of reconstructing permittivity of layered dielectric  inclusions. It is shown that the existence and uniqueness can be justified by  establishing one-to-one correspondence between the sought quantities and the  measured noisy data.

##### Keywords
mathematical methods; inverse waveguide problems; permittivity reconstruction; measured noisy data; layered dielectric inclusions
Mathematics
##### Identifiers
urn:nbn:se:hig:diva-31293 (URN)978-1-7281-4473-3 (ISBN)
##### Conference
2019 IEEE Microwave Theory and Techniques in Wireless Communications (MTTW)
Available from: 2019-12-13 Created: 2019-12-13 Last updated: 2019-12-13Bibliographically approved

#### Search in DiVA

Show all publications