The paper is a review of the results of studies carried out in Francisk Skorina Gomel State University within the framework of the “Multifunctional materials and technologies” direction, priority areas of scientific research of the Republic of Belarus for 2016-2020.

Keywords: metamaterial, anechoic chamber, coating, vacuum-plasma technology, sol-gel technology.

S.A. Khakhomov – Rector of F. Skorina Gomel State University

I.V. Semchenko – Prorector of F. Skorina Gomel State University

A.P. Balmakou – Faculty of Physics and Information Technology, F. Skorina Gomel State University

A.L. Samofalov – Faculty of Physics and Information Technology, F. Skorina Gomel State University

Expressions for the magnitude and potential of the gravitational field of a massive spherical shell are obtained. It is shown that the differential equation obtained for the intensity is nonlinear. The relations obtained are a generalization for the strength and potential of the gravitational field in the nonrelativistic case.

Keywords: theory of gravitation, gravitational field intensity, field potential.

N.A. Akhramenko – Belarusian State University of Transport, Gomel

The photonic crystals that occur naturally in feathers of some species of birds involving structural type of coloration from the perspective of optical applications are investigated. A parametric 3D model of the photonic crystal composed of solid cylindrical melanosomes embedded in keratin matrix for studying how the geometry of the structure relates to optical properties was developed. Potentially the key features embedded by nature into the design of the photonic crystals in bird’s feathers can be successfully technically utilized for sensing application in optical wave range. The possible sensing appliances of this type might advance regarding to low power consumption, high sensitivity, small dimensions etc.

Keywords: photonic crystal, structural coloration, optical sensors, reflectance.

A.P. Balmakou – Faculty of Physics and Information Technology, F. Skorina Gomel State University

S.A. Khakhomov – Rector of F. Skorina Gomel State University

N.A. Aleshkevich – F. Skorina Gomel State University

I.V. Semchenko – Prorector of F. Skorina Gomel State University

D.G. Stavenga – University of Groningen, Netherlands

J. Wang – Jiangnan University, China

The ultra-thin phase metasurface structures based on the complementary square split ring nanoantenna have been proposed to achieve the THz optical metalenses with multi-dimensional and multi-focusing. The Fabry – Perot resonance mode could be usefully employed in explaining the principle of beam propagation and efficient transmission. The THz metalens can transfer the linear cross-polarization efficiently under the effect of the gratings on the incident plane. By locally tailoring edge lengths and opening angles of the split rings, full control over abrupt phase changes can be achieved. Two symmetrically distributed parallel focal spots and two vertical focal spots with arbitrary distance are obtained by arranging the SSRs units on the metalenses. Furthermore, we apply the concept of partitioned phase mode to realize the double-focusing metalens in the longitudinal direction, which provides a flexible and convenient method for focusing properties.

Keywords: metasurface, phase modulation, THz, Fabry – Perot, optical phase.

J. Ma – Jiangnan University, China

C. Song – Jiangnan University, China

Z.-D. Hu – Jiangnan University, China

A.P. Balmakou – Faculty of Physics and Information Technology, F. Skorina Gomel State University

S.A. Khakhomov – Rector of F. Skorina Gomel State University

J. Wang – Jiangnan University, China

T. Sang – Jiangnan University, China

Optical and photoelectrical properties of ZnO:Me:RE³⁺ thin films on glass and silicon substrates, formed by means of the sol-gel technique by the spin-coating method are presented. It is shown, that the Al/ZnO:Me:RE³⁺/Si structures obtain photosensitivity in visible and IR spectral ranges. Characteristics obtained for the system “Solar Cell / ZnO:Me:RE³⁺/ glass” have presented a possibility of the use of the studied system as the down-converter of the entering irradiation, as it gives a contribution to the performance factor of the individual solar cell as compared to the “Solar Element/ZnO:Al/glass” system.

Keywords: zinc oxide, rare-earth ions, silicon solar cells, transmission, photosensitivity, spectrum conversion.

V.V. Malyutina-Bronskaya – State Scientific and Production Association “Optics, Optoelectronics and Laser Technology”, Minsk

V.B. Zalesski – State Scientific and Production Association “Optics, Optoelectronics and Laser Technology”, Minsk

A.V. Semchenko – Faculty of Physics and Information Technology, F. Skorina Gomel State University

V.V. Sydsky – Faculty of Physics and Information Technology, F. Skorina Gomel State University

The results of investigation of photoacoustic transformation of different modes BLB in gyrotropic layered media are submitted at piezoelectric detection method of registration of a resulting signal. Following the obtained expressions, it is showed that the amplitude of a photoacoustic signal is determined by the thermophysical characteristics of layered media with internal stress, absorption coefficient and parameter of circular dichroism of gyrotropic layered media, polarization and energy characteristics of BLB, frequency of amplitude modulation, and also by geometry system piezolelectric sensor – gyrotropic layered sample.

Keywords: photoacoustic transformation, piezoelectric spectroscopy, Bessel light beam, energy dissipation, Bessel function, heat equation, gyrotropic layered media, Murnaghan constants, Lame coefficients.

G.S. Mityurich – F. Sñorina Gomel State University; Belarusian Trade and Economics University of Consumer Cooperatives, Gomel

E.V. Lebedeva – Belarusian Trade and Economics University of Consumer Cooperatives, Gomel

M. Aleksiejuk – Institute of Fundamental Technological Research Polish Academy of Sciences, Warsaw

A.N. Serdyukov – Faculty of Physics and Information Technology, F. Skorina Gomel State University

Broadband perfect metamaterial absorber has broad application prospects in the fields of radar target stealth, antenna design and electromagnetic protection. The existing multi frequency absorber will increase the size or thickness of the structure. This paper presents broadband polarization insensitive perfect metamaterial absorber based on fractal structure. Through the combination of fractal and circular structures, the bandwidth is extended without increasing the size of the structure. A simple equivalent circuit model has been proposed describing the absorption phenomenon to estimate the frequency of absorption of the proposed absorber. The simulated result shows that the absorber’s relative full width half maximum is 11.7%. The operating angles which the metamaterial structure can maintain 50% of the absorbance are 50 degrees. With rotational symmetry structure, the absorber is insensitive to the polarization. This structure is made and measured at X-band, the experimental results coincide well with the simulation results.

Keywords: metamaterial, broadband perfect absorber, fractal structure.

S. Fan – Nanjing University of Science & Technology, China

Y. Song – Nanjing University of Science & Technology, China

X. Zhang – Nanjing University of Science & Technology, China

In the framework of the thermoelasticity theory, a comparative analysis of the temperature fields and fields of thermoelastic stresses arising in the plates of crystalline sapphire in the process of single-beam and two-beam controlled laser thermosplitting is carried out using round and crescent-shaped beams. It is shown that the use of crescent-shaped beams provides the formation of tensile stresses necessary for the stable realization of the laser thermosplitting process, with a significant reduction in the maximum temperatures in the samples compared with the use of round-shaped beams.

Keywords: thermosplitting, modeling, finite element method, temperature, single crystal, sapphire, thermoelastic stresses.

S.V. Shalupaev – Faculty of Physics and Information Technology, F. Skorina Gomel State University

Y.V. Nikitjuk – Faculty of Physics and Information Technology, F. Skorina Gomel State University

A.A. Sereda – Faculty of Physics and Information Technology, F. Skorina Gomel State University

It is impossible to define the product of arbitrary generalized functions in the classical theory of distributions. That is an obstacle for applications generalized functions theory to equations with generalized coefficients and nonlinear problems. The common approach for solving the problem of generalized functions multiplication consists in constructing a differential algebra G according to the given space of generalized functions E and building an embedding Such algebras G are called Colombeau type algebras and their elements are called new generalized functions or mnemofunctions. The algebra of mnemofunctions on the circle is constructed in this article. By this example some general questions on algebras of mnemofunctions are formulated.

Keywords: generalized function, space of periodic generalized functions, mnemofunction, Colombeau type algebra.

A.B. Antonevich – Belarusian State University, Minsk

T.R. Shahava – Belarusian State University, Minsk

E.V. Shkadinskaia – Belarusian State University, Minsk

The structure of a finite group G with a proper subgroup H which is permutable with all subgroups of Schmidt of group G (then H is called S-quasinormal subgroup) is investigated.

Keywords: Schmidt group (minimal nonnilpotent group), permutable subgroups, solvable group.

S.Yu. Bashun – Polotsk State University, Novopolotsk

E.Ì. Palchik – Polotsk State University, Novopolotsk

The necessary condition under which the system of two linear discrete periodic equations has strongly irregular periodic solutions was obtained.

Keywords: strongly irregular periodic solution, linear discrete system, periodic equation.

M.S. Belokursky – Faculty of Mathematics and Programming Technologies, F. Skorina Gomel State University

A.C. Demenchuk – Institute of Mathematics of NAS of Belarus, Minsk

The permutability of elements in polyadic groupoids with polyadic operation which is determined on a k-th Cartesian power A^k of n-ary groupoid with the substitution of the set {1, ..., k} and n-ary operation is studied.

Keywords: semigroup, polyadic operation, semiabelianness, neutral sequence.

A.M. Gal'mak – Mogilev State University of Food Technologies

The equivalence of the generalized modulus of smoothness defined by the generalized shift operator of Jacobi type and the K-functional of Petre is proved.

Keywords: generalized Jacobi shift operator, generalized modulus of smoothness, K-functional.

G.N. Kazimirov – Faculty of Mathematics and Programming Technologies, F. Skorina Gomel State University

For a saturated formation the problem of complementability of -residual in extension of the finite group which is the product of normal subgroups is established.

Keywords: finite group, formation, residual, complement, saturated Fitting formation.

S.F. Kamornikov – F. Skorina Gomel State University

O.L. Shemetkova – Plekhanov Russian University of Economics, Moscow

Composition factors of finite groups in which each subgroup odd order is nilpotent were defined.

Keywords: finite group, simple non-abelian group, group Schmidt.

V.N. Tyutyanov – International University «MITSO», Gomel

P.V. Bychkov – F. Skorina Gomel State University

A website has been developed with the help of which the user can select a group of areas of activity or professions that are acceptable to him. The scheme for the application of software tools, brief description of psychological tests, structure of the database, description of the main features of the software implementation and the user interface of the web application are attached. The results of the preliminary approbation of the selection of professions with the use of psychological tests and the square of Pythagoras are presented.

Keywords: sphere of activities, profession, algorithm of Pythagoras, psychological tests.

A.N. Osipenko – P.O. Sukhoi Gomel State Technical University

N.B. Osipenko – Faculty of Mathematics and Programming Technologies, F. Skorina Gomel State University

Y.À. Slepianok – Faculty of Mathematics and Programming Technologies, F. Skorina Gomel State University

The principles of the operation of a computer system for transmitting and processing information using infrared radiation are considered. Interaction of the user with a system that allows recreating the operation of firearms: to produce shots, reload weapons and monitor the status of the system using the display is implemented. The possibility of a configuring and polling parameter values using console commands is described. Using finite state machines makes the computer system adaptable and extensible. In practical application, the developed system can be used by law enforcement and military authorities to train combat skills.

Keywords: information, infrared radiation, firing, weapon, finite state machine, user, display, software.

A.À. Petushkov – Faculty of Mathematics and Programming Technologies, F. Skorina Gomel State University

M.I. Zhadan – Faculty of Mathematics and Programming Technologies, F. Skorina Gomel State University

An approach is proposed for reliability analysis of a technical system, which is specified by the graph of states, using simulation. This method overcomes the limitations of the Markov method of analysis. The model, software and technology of investigation of the reliability of a technical system are proposed. The performance of the computational process and the accuracy of modeling, depending on the type and properties of the computer system and the number of computational flows are investigated.

Keywords: reliability, graph of states, simulation modeling, computer system, performance of computational process.

D.N. Shevchenko – Belarusian State University of Transport, Gomel

A.U. Litvin – Belarusian State University of Transport, Gomel

M.A. Fedianin – Belarusian State University of Transport, Gomel