121 research outputs found
Application of the asymptotic solution to EM field scattering problem for creation of media with prescribed permeability
No full textScattering of electromagnetic (EM) waves by many small impedance particles (bodies), embedded in a homogeneous medium, is studied. Physical properties of the particles are described by their boundary impedances. The limiting equation is obtained for the effective EM field in the limiting medium, in the limit a→0, where a is the characteristic size of a particle and the number M(a) of the particles tends to infinity at a suitable rate. The proposed theory allows one to create a medium with a desirable spatially inhomogeneous permeability. The main new physical result is the explicit analytical formula for the permeability μ(x) of the limiting medium. The computational results confirm a possibility to create the media with various distributions of μ(x)
Scattering of electromagnetic waves by many thin cylinders: theory and computational modeling
No full textРозсіювання хвиль ЕМ на неплощинних структурах із вбудованим набором мікро включень (Scopus)
No full textAndriychuk M. EM Wave Scattering on the Non-Planar Structures with Embedded Set of Micro Inclusions / Mykhaylo Andriychuk, Volodymyr Senyk // 2020 IEEE XXVth International Seminar/Workshop Direct and Inverse Problems of Electromagnetic and Acoustic Wave Theory (DIPED) 15-18 Sept. 2020. - https://ieeexplore.ieee.org/document/9273380Досліджено характеристики електромагнітного (ЕМ) розсіювання
для плоских некоординатних неоднорідних структур, вбудованих низкою
включень малого розміру імпедансу. Відстань між сусідніми частинками
нараховує кілька її діаметрів, а щільність включень передбачена конкретним
законом. Явна формула для компонентів ЕМ поля зменшена. Вивчено
характеристики збіжності ітераційної процедури побудови для отримання
допоміжних складових ЕМ поля та представлено залежність характеристик
розсіювання від геометрії включень. The electromagnetic (EM) scattering characteristics are studied for the
planar non-coordinate inhomogeneous structures embedded by series of small-size
impedance inclusions. The distance between the neighboring particles counts several
its diameters, and the density of inclusions is prescribed by the specific law. The
explicit formula for the EM field components is reduced. The characteristics of
convergence of the build iterative procedure to obtain the auxiliary components of
the EM field are studied, and dependence of scattering characteristics on the
geometry of inclusions is presented
Creating Media with Prescribed Permeability Using the Asymptotic Solution to EM Wave Scattering Problem
No full textAsymptotic solution to scattering problem of electromagnetic (EM) waves by many small impedance particles, embedded in a homogeneous medium, is applied for creating media with prescribed permeability. Physical properties of the particles are described by their boundary impedances. The limiting equation is obtained for the effective EM field in the resulting medium. The proposed theory allows one to create a medium with a desirable spatially inhomogeneous permeability. The main new physical result is the explicit analytic formula for the permeability μ(x) of the limiting medium. The computational results confirm a possibility to create the media with various distributions of μ(x)
Scattering by many small particles and creating materials with a desired refraction coefficient.
No full textCombining an asymptotic method and computational modelling the authors propose a method for creating materials with the desired electrodynamical characteristics, in particular, with a desired refraction
coefficient. The problem of wave scattering by many small particles is solved asymptotically under the assumptions ka 1, d a, where a is the size of the particles and d is the distance between the neighbouring particles. On the wavelength one may have many small particles.
Impedance boundary conditions are assumed on the boundaries of small particles. The results of numerical simulation show good agreement with the theory. Constructive conclusions are given for creating materials with a desired refraction coefficient on the basis of the obtained numerical results. Engineering realisation of the theory is of practical interest
Light pulsed irradiation in growing seedlings
No full textThis work presents the research results of dynamic characteristics of ARPL-1W LEDs with a narrow-spectrum composition of luminescence (red, green, blue) using switching power supply of U-shaped pulses. Based on the results of increase and decrease of light flux and analysis of the kinetics of photosynthetic processes, from light absorption to absorption of CO2 from the atmosphere and the formation of carbohydrates, the LED irradiation installation is designed and approbated for growing seedlings. According to the results of experimental studies it is shown that pulsed irradiation stimulates faster plant growth without losing their morphometric parameters
Радіаційні властивості площинної маси, що складається з мікрочастинок імпедансу (Scopus)
No full textAndriychuk M. Radiation properties of plane array consisting of impedance micropatricles / Mykhaylo Andriychuk, Volodymyr Senyk // XIVth International Conference of Perspective Technologies and Methods in MEMS Design (MEMSTECH), Polyana, April 18-22, 2018. – P. 170-173. - https://ieeexplore.ieee.org/document/8365726Задача розсіювання електромагнітних (ЕМ) хвиль на масиві дрібних (мікро) частинок розглядається з використанням асимптотичного підходу. Це дає при отриманні явної формули для компонентів розсіяного ЕМ-поля для однієї частинки та відповідної лінійної алгебраїчної системи (ЛАС) для невідомих коефіцієнтів у серії представлення компонентів ЕМ-поля для багатьох частинок. Відповідні LAS для вищезазначених коефіцієнтів ефективно вирішуються методом послідовного наближення. Вивчено радіаційні характеристики плоскої решітки, що складається з набору частинок імпедансу. The electromagnetic (EM) wave scattering problem on an array of small (micro) particles is considered using the asymptotic approach. This yields in receiving an explicit formula for components of scattered EM field in the case of one particle and a respective linear algebraic system (LAS) for unknown coefficients in the series of presentation of the EM field components in the case of many particles. The respective LAS for above coefficients is solved effectively by the successive approximation method. The radiation characteristics of plane array consisting of a set of impedance particles are studied
Numerical solution of many-body wave scattering problem for small particles and creating materials with desired refraction coefficient
No full textTheory of wave scattering by small particles of arbitrary shapes was developed by A. G. Ramm in papers (Ramm, 2005; 2007;a;b; 2008;a; 2009; 2010;a;b) for acoustic and electromagnetic (EM) waves. He derived analytical formulas for the S-matrix for wave scattering by a small body of arbitrary shape, and developed an approach for creating materials with a desired spatial dispersion. One can create a desired refraction coefficient n 2 (x, ω) with a desired x, ω-dependence, where ω is the wave frequency. In particular, one can create materials with negative refraction, i.e., material in which phase velocity is directed opposite to the group velocity. Such materials are of interest in applications, see, e.g., (Hansen, 2008; von Rhein et al., 2007). The theory, described in this Chapter, can be used in many practical problems. Some results on EM wave scattering problems one can find in (Tatseiba & Matsuoka, 2005), where random distribution of particles was considered. A number of numerical methods for light scattering are presented in (Barber & Hill, 1990). An asymptotically exact solution of the many body acoustic wave scattering problem was developed in (Ramm, 2007) under the assumptions ka << 1, d = O(a 1/3), M = O(1/a), where a is the characteristic size of the particles, k = 2π/λ is the wave number, d is the distance between neighboring particles, and M is the total number of the particles embedded in a bounded domain D ⊂ R 3 . It was not assumed in (Ramm, 2007) that the particles were distributed uniformly in the space, or that there was any periodic structure in their distribution. In this Chapter, a uniform distribution of particles in D for the computational modeling is assumed (see Figure 1). An impedance boundary condition on the boundary Sm of the m-th particle Dm was assumed, 1 ≤ m ≤ M. In (Ramm, 2008a) the above assumptions were generalized as follows
Розсіювання хвиль ЕМ на тонких гнучких плівках, доповнене набором мікрочастинок (Scopus)
No full textAndriychuk M. EM Wave Scattering on Thin Flexible Films Supplemented by a Set of Micro Particles / Mykhaylo Andriychuk, Yarema Kuleshnyk, Volodymyr Senyk // Proc. of 2020 IEEE XVIth International Conference on Perspective Technologies and Methods in MEMS Design, Lviv, Ukraine. - PP. 64-67. - https://ieeexplore.ieee.org/document/9109498На основі асимптотичного підходу вивчається проблема розсіювання електромагнітних (ЕМ) хвиль на тонкому шарі (плівці) за наявності набору дрібних частинок. Розмір частинки на порядок менше відстані між сусідніми частинками; кількість частинок велика, і вони розподіляються з особливою щільністю у вихідному матеріалі. Близкий спосіб вирішення проблеми розсіювання зведений. Характеристики розсіювання структури вивчаються для різних геометричних параметрів у випадку плоскої падаючої хвилі. The problem of electromagnetic (EM) wave scattering on thin layer (film) in presence of a set of small particles is studied based on the asymptotic approach. The size of particle is of order less than the distance between the adjacent particles; the number of particles is big and they are distributed with peculiar density in the initial material. A close form of solution to the scattering problem is reduced. The scattering characteristics of structure are studied for the different geometrical parameters in the case of plane incident wave
Between Microeconomics and Geopolitics: On the Reasonable Application of Competition Law
No full text\ua9 2021 The Author. The Modern Law Review \ua9 2021 The Modern Law Review Limited.For decades competition law was interpreted and applied through the prism of the economic analysis of law. This approach has advantages, enabling one to master both the methodological and normative features of the field. The use of economic rationality helps one to understand the motivation of market agents. The use of advanced mathematics allows robust modelling of the wide variety of empirical and theoretical factors. The use of efficiency and consumer welfare helps one to calibrate the goals of competition law. Such a ‘standard’ perception of the discipline, however, is in a deep crisis, and – as this article explains – chiefly for the right reasons. The conceptual divide between the representatives of Law and Economics and those adhering to a more societal account of competition law has many levels and dimensions. This article investigates the foundational aspect of the divide: the divergence in epistemic perception of legal and economic expertise
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