bluuebunny/crossref_metadata_2025 huggingface dataset:
Supraglacial Soils and Soil-Like Bodies: Diversity, Genesis, Functioning (Review)
Authors: Mergelov N. S. , Goryachkin S. V. , Zazovskaya E. P. , Karelin D. V. , Nikitin D. A. , Kutuzov S. S.
Published: April 2024

In the 21st century, glaciers are percepted as a distinct biome that has taken on special significance in today’s world of retreating ice. Here we review the results of recent studies of organomineral formations on glaciers, their diversity, processes, functioning and the role in the biosphere. The question is raised about the possibility of involving supraglacial organomineral formations in the range of objects of soil science. We review the supraglacial zone as an area of soils and soil-like bodies, which biogeochemical processes affect the glacial biome and its surrounding landscapes. Interpretation of supraglacial organomineral formations from a soil scientist point of view revealed the following processes: accumulation and stabilization of organic matter (OM), its heterotrophic transformation, formation of dark-colored humified OM and accumulation of residual solid-phase products of functioning in situ, fine earth aggregation, and biochemical weathering. Among supraglacial formations, we distinguish pre-soils and soil-like bodies in ice and snow, metastable soil-like bodies on cryoconite and soils with microprofiles under moss communities on ice, as well as relatively stable soils with macroprofiles on fine-earth-detrital deposits with underlying glaciers and dead ice. Labile water-soluble OM, accumulated and transformed in supraglacial soils and soil-like bodies, has a significant impact on the periglacial zone, leading to the reservoir and priming effects. The studies of supraglacial organomineral systems are of fundamental importance for understanding the evolution of ecosystems on Earth as well as for modeling supraglacial formations of extraterrestrial bodies with a vast cryosphere. Supraglacial soil formation is also a model object for studying common soils under conditions of a constant external input of organic and mineral components, which contribution outside the glaciers is no less significant, but is masked by the polymineral substrate of soils and parent rocks.
One Class of Resonance Precession Motions of a Rigid Body under the Action of Three Homogeneous Force Fields
Authors: Gorr G. V.
Published: April 2024

The article is devoted to the problem on motion of a rigid body with a fixed point under the action of a force field, which is the superposition of three homogeneous force fields. Existence conditions are investigated for precession motions, which are characterized by the following property: the angular velocity of the precession of the body is two times more than the angular velocity of its proper rotation. It is established that the body has the dynamic symmetry with respect to an axis making a constant angle with a vector fixed in the immovable space. In the case of the body with the spherical mass distribution this angle equals to \({\text{arccos}}\frac{1}{4}\). Solution of the equations of motion of the body is expressed through the elliptic functions of time.
Flow Structure of a Three-Dimensional Turbulent Wall Jet
Authors: Gaifullin A. M. , Shcheglov A. S.
Published: April 2024

A numerical simulation is conducted to study the flow of a three-dimensional incompressible wall jet. The study is aimed to determine the flow structure and to compare the propagation mechanisms of turbulent and laminar wall jets. The numerical solution of the Navier–Stokes equations in the turbulent case is obtained using the wall-resolved large eddy simulation. The simulation results are compared with experimental data.
Solitary Waves in Two-Layer Fluid with Piecewise Exponential Stratification
Authors: Makarenko N. I. , Maltseva J. L. , Cherevko A. A.
Published: April 2024

The problem on internal stationary waves in a two-layer fluid with density, depending exponentially on the depth inside the layers and having a jump at the interface, is considered. A non-linear equation of the second-order long-wave approximation is derived, and their asymptotic submodels, describing solitary waves of finite amplitude, are discussed. Dispersive properties and wave propagation regimes depending on dimensionless parameters of the background piecewise constant flow are studied.
On Some Regularities of Realization of Electrostatic Instability of Charged Surface of Liquid in Basin of Finite Dimensions
Authors: Grigor’ev A. I. , Shiryaeva S. O. , Koromyslov V. A.
Published: April 2024

Physical regularities of realization of electrostatic instability of flat charged surface of non-compressible viscous conducting liquid are considered, in pool of finite dimensions, where spectrum of emerging capillary waves is discrete. It has been shown that the critical conditions for the onset of electrostatic instability of an uncompressible viscous conductive liquid, in a basin of finite dimensions, coincide with those for a limitless surface of an infinitely deep ideal uncompressible liquid (coincide with the conditions for realizing Tonks–Frenkel instability). This allows the experimental verification of the criterion for realizing Tonks–Frenkel instability to use basins of finite dimensions, avoiding fundamental errors.
Necessary Conditions for Development of Inviscid Instabilities in a Vibrationally Excited Dissociating Gas
Authors: Grigoryev Yu. N. , Ershov I. V.
Published: April 2024

For a plane flow of a vibrationally excited dissociating diatomic gas the necessary conditions of the existence of growing (neutral) inviscid perturbations, similar to the Rayleigh criterion of a “generalized” inflection point, are obtained. The corresponding formulas are presented for cases with a certain physical interpretation. In particular, the model of a vibrationally excited one-component gas is considered as the initial stage of thermal dissociation, as well as a wide spread model with one dissociation-recombination reaction. The case of a binary molecular-atomic mixture with a vibrationally excited molecular component and a “frozen” gas-phase dissociation-recombination reaction is considered as an intermediate one. Comparative numerical calculations were carried out, which showed, in particular, that under conditions of developed dissociation, the use of the criterion of the “generalized” inflection point does not take into account the specifics of the process. The wave numbers and phase velocities of the I and II inviscid modes calculated on its basis may differ significantly from the results obtained using the new necessary condition.
Simulation of Tthe Amplitude of Transverse Oscillations of the Rod System upon Impact of a Falling Load, Taking into account Deformation in the Contact Area
Authors: Bityurin A. A.
Published: April 2024

The oscillatory process of a rod system of arbitrary shape under shock interaction with a falling load is considered. The system may consist of a large number of rods connected to each other rigidly or pivotally, and striking is assumed to be one of the core elements, thus causing a complex oscillatory process.
As an example, vibrations of a rigidly sealed statically indeterminate flat two-post frame experiencing a drop of a load of a given mass and pre-impact velocity are simulated. One of the vertical pillars of the frame has an initial curvature, the presence of which affects the maximum amplitude of transverse vibrations arising from impact. The impact of the load on the frame crossbar is modeled taking into account the deformation in the contact area, which is justified from the point of view of the accuracy of the calculations, because otherwise the magnitude of the impact force will be overestimated. When modeling the impact interaction of the load and the rod system under consideration, it is assumed that the falling load has the shape of a cylinder with a certain length of the generatrix. Linearization of the relationship between force and deformation of cylindrical surfaces is used.
The proposed method of modeling the amplitude of transverse oscillations makes it possible to further study the characteristics of the oscillatory process depending on the mass of the falling load and its pre-impact velocity, as well as on the configuration of the rod system. The relevance of the work for calculations of structural elements of various purposes experiencing impact is emphasized, since the presented model can be used for engineering calculations of a wide class of core systems.
Constraints in the Problem of Calculating Optimal Trajectories for a Supersonic Non-Maneuverable Aircraft
Authors: Kumakshev S. A. , Shmatkov A. M.
Published: April 2024

The influence of phase and other constraints on the method of searching for the trajectories of the movement of a civil supersonic aircraft, which are optimal in terms of fuel consumption, is considered. Based on the solutions found by the dynamic programming method, taking into account numerous restrictions on flight altitude, pitch angle, normal high-speed overload, aircraft speed, engine thrust, etc., it is shown that almost all of these conditions can be ignored during the initial stage of calculations, since the optimal solution does not reach them. Therefore, one can first apply the maximum principle, and use the dynamic programming method only in those cases where a substantial part of the constraints turns out to be significant.
On Resonant Values of Parameters in the Problem on the Stability of Lagrangian Solutions in the Near-Circular Restricted Three-Body Problem
Authors: Markeev A. P.
Published: April 2024

The restricted problem of three bodies (material points) moving under the action of gravitational attraction according to Newton’s law is considered. The orbits of the main attracting bodies are considered to be ellipses with a small eccentricity, and a passively gravitating body can perform arbitrary spatial motion near the triangular libration point. For the Hamiltonian function corresponding to such a motion, the structure of the normal form is pointed in the cases of third-order resonances. In the planar restricted three-body problem, the equations up to the second degree of eccentricity for resonance curves for all resonances up to the sixth order inclusive are obtained.
Application of the Method of Fast Expansions to Construction of a Trajectory of Movement of a Body with Variable Mass from Its Initial Position in a Gained Final Position in a Gravitational Field
Authors: Chernyshov A. D. , Popov M. I. , Goryainov V. V. , Nikiforova O. Yu.
Published: April 2024

An analytical solution of the problem of the movement of a spacecraft from the starting point to the final point in a certain time is given. First, the method of fast sine expansions is used. The space problem considered here is essentially non-linear, what necessitates the use of trigonometric interpolation methods, which surpass all known interpolations in accuracy and simplicity. In this case, the problem of calculating Fourier coefficients by integral formulas is replaced by the solution of an orthogonal interpolation system. In this regard, two cases are considered on the segment \(\left[ {0,a} \right]\): universal interpolation and trigonometric sine and cosine interpolations. A theorem on the rapid decrease of expansion coefficients is proved, and a compact formula for calculating the interpolation coefficients is obtained. A general theory of fast expansions is given. It is shown that in this case, the Fourier coefficients decrease significantly faster with the growth of the ordinal number compared to the Fourier coefficients in the classical case. This property makes it possible to significantly reduce the number of terms taken into account in the Fourier series, significantly increase the accuracy of calculations and reduce the amount of calculations on a computer. The analysis of the obtained solutions of the spacecraft motion problem is carried out and their comparison with the exact solution of the test problem is proposed. An approximate solution by the method of fast expansions can be taken as an exact one, since the input data of the problem used from reference books have a higher error.
Bending Vibrations of an Elastic Rod Controlled by Piezoelectric Forces
Authors: Gavrikov A. A. , Kostin G. V.
Published: April 2024

Bending vibrations of a thin elastic rod of rectangular cross-section are studied. A number of piezoelectric actuators (elements) is symmetrically attached without gaps to two opposite sides of the rod. Each element is glued to the neighboring ones, forming with the rod a single elastic body in the form of a rectangular parallelepiped. The body is hinged at both ends relative to the cross-sectional axis parallel to the piezoelectric layers. In opposite piezoelements, homogeneous fields of normal stresses are set antisymmetrically as functions of time. These stresses are parallel to the axis of the rod and force the elastic system to perform bending motions. Within the framework of the linear theory of elasticity for the considered system, generalized formulations of the initial-boundary value problem and the corresponding eigenvalue problem are given. These problems are defined through unknown displacements and the time integrals of mechanical stresses. An approximation of the displacement and stress fields, which is polynomial in transverse coordinates, is proposed. This approximation exactly satisfies the homogeneous boundary conditions for stresses on the lateral sides and takes into account the symmetry properties of the bending motions. For the chosen approximation, the boundary value problem for eigenvalues is exactly solved. Two branches of eigenvalues are found and used to reduce the initial-boundary value problem to a countable system of first-order ordinary differential equations with respect to complex variables. The dynamical system is decomposed into independent infinite-dimensional subsystems with a scalar control input. One of these subsystems is not controllable. For the remaining subsystems, each corresponding to a pair of piezoelectric elements, a control law for vibration damping is proposed for a specific number of the lower modes associated with the lower branch.
Quaternion Regularization of Singularities of Astrodynamic Models Generated by Gravitational Forces (Review)
Authors: Chelnokov Yu.N.
Published: April 2024

The article presents an analytical review of works devoted to the quaternion regularization of the singularities of differential equations of the perturbed three-body problem generated by gravitational forces, using the four-dimensional Kustaanheimo–Stiefel variables. Most of these works have been published in leading foreign publications. We consider a new method of regularization of these equations proposed by us, based on the use of two-dimensional ideal rectangular Hansen coordinates, two-dimensional Levi-Civita variables, and four-dimensional Euler (Rodrigues–Hamilton) parameters. Previously, it was believed that it was impossible to generalize the famous Levi-Civita regularization of the equations of plane motion to the equations of spatial motion. The regularization proposed by us refutes this point of view and is based on writing the differential equations of the perturbed spatial problem of two bodies in an ideal coordinate system using two-dimensional Levi-Civita variables to describe the motion in this coordinate system (in this coordinate system, the equations of spatial motion take the form of equations of plane motion) and based on the use of the quaternion differential equation of the inertial orientation of the ideal coordinate system in the Euler parameters, which are the osculating elements of the orbit, as well as on the use of Keplerian energy and real time as additional variables, and on the use of the new independent Sundmann variable. Reduced regular equations, in which Levi-Civita variables and Euler parameters are used together, have not only the well-known advantages of equations in Kustaanheimo–Stiefel variables (regularity, linearity in new time for Keplerian motions, proximity to linear equations for perturbed motions), but also have their own additional advantages: 1) two-dimensionality, and not four-dimensionality, as in the case of Kustaanheimo-Stiefel, a single-frequency harmonic oscillator describing in new time in Levi-Civita variables the unperturbed elliptic Keplerian motion of the studied (second) body, 2) slow change in the new time of the Euler parameters, which describe the change in the inertial orientation of the ideal coordinate system, for perturbed motion, which is convenient when using the methods of nonlinear mechanics. This work complements our review paper [1].
Extraction of U(VI), Th(IV), REE(III), and Sc(III) from Nitrate and Perchlorate Solutions with 1,5-bis[di(p-tolyl)phosphoryl]-3-oxapentane
Authors: Turanov A. N. , Karandashev V. K. , Baulin V. E. , Baulin D. V.
Published: April 2024

Received January 16, 2023; revised March 21, 2023; accepted March 27, 2023 Extraction of U(VI), Th(IV), REE(III), and Sc(III) from nitrate and perchlorate solutions with solutions of phosphorylpodand 1,5-bis[di( p -tolyl)phosphoryl]-3-oxapentane (L) in 1,2-dichloroethane depending on the concentration of acids in the aqueous phase was studied. The stoichiometry of the extractable complexes was determined. It was found that, as the concentration of acids increases, the magnitude of the «perchlorate» e ect decreases, and at acid concentrations above 0.3 mol/L, REE(III) ions are extracted by podand L from HClO4 solutions less e ciently than from HNO3 solutions. During the extraction of Sc(III), the «perchlorate» e ect also manifests itself in the region of high acid concentration, which leads to an increase in the separation coe cients of Sc(III) and REE(III), U(VI), and Th(IV) during extraction with podand L from HClO4 solutions.
Diffusion of tritium, technetium, cesium, and uranium from phosphate glass leachates in pore solution of clay materials
Authors: Martynov K. V. , Konevnik Yu. V. , Zakharova E. V.
Published: April 2024

The through diffusion method at room temperature was used to study the migration of radionuclides (3H, 99Tc, 137Cs, 233U) in compacted samples of clay materials during pore diffusion from a model leachate of the RW phosphate matrix with a total salt content of about 400 mg/L. Based on the results of the experiments, the effective diffusion coeffcients and coeffcients of the sorption distribution of radionuclides for the studied barrier clay materials were determined. Regularities of the diffusion transfer of tritium, cesium and uranium depending on the structure, mineral composition of clay materials and the content of radionuclides in the pore solution are revealed. Numerical modeles are proposed for calculating the effective pore di usion coeffcients of these radionuclides. There are still insuffcient data to analyze the factors affecting the diffusion of technetium.
In uence of the nature of the diluent on the extraction capacity of N,N,N',N'-tetrabutyldiglycolamide to Eu(III), Am(III) and Cm(III)
Authors: Sharov V. E , Kostikova G. V
Published: April 2024

The in uence of HNO3 concentration on the extraction of Eu(III), Am(III) and Cm(III) by N,N,N',N'tetrabutyldiglycolamide in 5 diluents (nitrobenzene, toluene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane and chloroform) was studied. The dependence of the distribution ratios of the listed metals on the nature of the diluent was examined. The extraction of Eu(III), Am(III) and Cm(III) decreases in the following order: nitrobenzene > m -tri uoromethylnitrobenzene > mixture of n -dodecane and decanol-1 (90 : 10 vol/vol) > tetrachloromethane > 1,2-dichloroethane > benzene > 1,1,2,2-tetrachloromethane > toluene > chloroform. The conditions for the separation of Eu(III)/Am(III) and Am(III)/Cm(III) pairs were determined. The explanation of the observed increase of the Am(III)/Cm(III) separation factors with the increase of the nitric acid concentration in the equilibrium aqueous phase was suggested.
Comparative analysis of experimental data on the sublimation of uranium carbonitrides and uranium-zirconium carbonitrides at high temperatures
Authors: Bulatov G. S. , German K. E.
Published: April 2024

The review is devoted to a comparison of new experimental data on the sublimation of uranium-zirconium carbonitrides with di erent contents of carbon, nitrogen, and oxygen impurities at high temperatures (1700- 2300 K), obtained by us in the past 2 years, with data of previous works presented in the literature on the sublimation of uranium carbonitrides, obtained by us and by other authors using mass spectrometry and some other methods of thermodynamic analysis. The main attention is paid to the consideration of the composition of the gas phase and the analytical dependences of the partial pressures of its components on temperature, as well as the chemical mechanism and heats of sublimation. The main feature of the sublimation process of all materials based on uranium carbonitride (both pure and doped with zirconium) is its incongruent nature, due to the loss of nitrogen, which leads to a shift in their compositions towards the phase with higher carbon content. The chemical mechanisms of sublimation of carbonitrides of both types are considered, according to which oxygen impurities in these materials lead to the appearance of oxide components UO, UO2 and CO in the gas phase and additional release of nitrogen. The introduction of zirconium into uranium carbonitride and an increase in the carbon content in it lead to a decrease in the partial pressures of uranium monoxide and nitrogen, which increases the thermal stability of this innovative fuel material.
Sorption of Sr(II) ions with tricalcium phosphate in the presence of humic acids
Authors: Ioshin A. A. , Volkov I. V. , Polyakov E. V.
Published: April 2024

The sorption behavior of traces Sr(II) toward β-Ca3(PO4)2 (TCP) depending on the concentration of the cation, pH, and concentrations of humic acids (HA) in the solution was udied. Thermodynamic analysis of the solubility of TCP (1) was performed taking into account the formation of Ca(OH)2 (CH, 2), Ca(H2PO4)2 (MCPA, 3), CaHPO4·2H2O (DCPD, 4), Ca5(PO4)3OH (hydroxyapatite, OHAp, 5), and Ca2P2O7 (DCPP, 6). It is shown that, depending on the pH of the solution, the main equilibrium phases with the solution are phases (4) and (5). X-ray di raction analysis, Raman spectroscopy, and 31P NMR data of the phase (1) samples after contact with a solution of 0.01 mol/L NaNO3 for about 10 days showed the presence of only the phase (1). The solubility of (1) regarding the concentration of Ca2+, PO43- ions and the stoichiometric ratio (Ca/P) in solutions, depending on pH, corresponds to the presence of surface phases (4) or (5). The model of surface complexation in the Henry region adequately describes the mechanism of sorption of Sr(II) by the surface phase (5) on TCP particles in the form of the SrHPO40 complex. The formation of the HA complex Sr(II) in solution does not a ect distribution coe cient K d(Sr) in the range of HA concentrations of 0-150 mg/L due to the competitive e ect of hydrogen phosphate ions on strontium complexes.
Effect of a Strong Local Atmospheric Perturbation on the Propagation of Low-Frequency Electromagnetic Waves in the Earth Ionosphere
Authors: Moshkov A. V.
Published: April 2024

Coefficients of reflection and transmission of electromagnetic waves in a frequency interval of 1–10 kHz are numerically calculated for the passage through a flat inhomogeneous layer of the lower ionosphere in the presence of a strong local perturbation of the atmosphere. A point source of energy is used to simulate the perturbation. When the perturbation passes through the layer of the lower ionosphere, the wave transmission coefficient sharply decreases within 1–2 min while the diagonal components of the matrix of reflectioncoefficients increase to almost unity.
Experimental Investigation of a Relative Transmission Scheme on Chaotic Radio Pulses
Authors: Dmitriev A. S. , Mohseni T. I. , Petrosyan M. M.
Published: April 2024

The practical feasibility of a wireless relative transmission scheme based on chaotic radio pulses is demonstrated. New components necessary for the implementation of this scheme have been developed. A prototype of a transmission system in the frequency range of 200–500 MHz was created on which experiments were carried out on the transmission of binary information. The measurement results correspond to the previously obtained theoretical and computational estimates on the main properties and characteristics of a new transmission scheme that uses dynamic chaos as an information carrier.
Effect of Spontaneous Emission on Self-Oscillations in Fiber Lasers with Micro-Optomechanical Resonant Structures
Authors: Egorov F. A. , Nikitin V. V. , Potapov V. T.
Published: April 2024

Within the balanced approximation of fiber lasers (FLs) considered as distributed systems, an improved mathematical model is constructed that describes the low-frequency dynamics of FLs with mirrors based on optomechanical micro-oscillators (MOs), taking into account the effect of spontaneous emission (SE) localized in the cladding modes of the active fiber (AF). The mechanisms of the effect of SE on the synchronous self-oscillations (SSOs) in the FL–MO laser system are revealed: additional inversion removal in the AF due to the finite path length of SE cladding mode photons in the FL active medium, violation of the condition for the internal resonance in the laser system, and perturbation of MO oscillations by photoinduced force caused by SE. By means of numerical simulation of SSOs in an erbium–ytterbium FL with an MO and experimental studies, the dependence of the SSO frequency on the geometric-optical parameters of the AF and the reflectivity of the AF–environment interface has been established, which can be used to improve the frequency stability of laser pulses in fiber sources of pulsed radiation and create a new class of resonant fiberoptic sensors.
Identification of Signals Against Transformative Type Interference with Erasure
Authors: Klimov V. V.
Published: April 2024

The problem of identification of two sources of binary signals against a background of transforming and erasing types of noise under counteraction conditions is considered. The situation is described by an antagonistic game, the analytical solution of which gives the optimal strategies of the players and the price of the game as a function of the a priori probability of the appearance of one of the sources. Particular cases are considered.
Autonomous System for Energy Collection and Conversion Based on a Biofuel Cell
Authors: Kolesov V. V. , Smirnov A. V. , Serebrov M. M. , Kashin V. V. , Plekhanova Yu. V. , Reshetilov A. N.
Published: April 2024

Functioning of a prototype of a micropower system (energy storage device) consisting of a biofuel cell (BFC) and converter–capacitor is demonstrated. The system allows conversion of a low input voltage from an unstable energy source to a standard working voltage used in radio equipment. For the series connection of two biofuel cells, the voltage is summed up and amounts to ~500 mV, and the output storage capacitor of 100 μF is charged in 13 min to a working voltage of 3.1 V upon a cold start of the converter. It is shown that energy storage substantially depends on the capacitance of the final storage unit and on the type of energy consumption. The proposed system can be used for different unstable energy sources.
Optimization of the Guaranteed Information Transmission Rate
by Pseudorandom Signals with a Randomized Base in Conditions
of Intentional Interference
Authors: Chudnov A. M. , Kichko Ya. V. , Sapunova L. P.
Published: April 2024

The principles of analysis and optimization of the parameters and signal processing mode in an information transmission system with a reverse channel operating under the influence of intentional interference, the structure of which can be selected from the position of disruption (deterioration) of the system have been considered. An algorithm for the formation and processing of pseudorandom signals with a randomized base is proposed, which provides an increase in the speed of information transmission by the system in theclass of interference with limited average power while ensuring the initial reliability indicators. The methodology is presented, calculation examples are given, and graphs of the dependences of the guaranteed informationtransfer rate in a system with a randomized two-stage switching of the signal base from the average power of the optimized interference are shown.
Two-Dimensional Problems of Achieving Super-Resolution in Radar and Remote Sensing
Authors: Lagovskii B. A. , Samokhin A. B.
Published: April 2024

A signal processing technique is proposed that allows one to reconstruct two-dimensional radio images of objects with angular super-resolution. The method of double orthogonalization is justified, which allows one to increase the level of the achieved super-resolution. The limiting possibilities of obtaining adequatesolutions to inverse problems in the presence of a priori information about the solution are shown.
Magnetocaloric Effect in a Ni2.25Mn0.75Ga0.93Si0.07 Alloy
Authors: Gaifullin R. Yu. , Gadzhiev A. B. , Aliev A. M. , Taskaev S. V. , Musabirov I, I.
Published: April 2024

The results of a study of the magnetocaloric effect (MCE) in Ni2.25Mn0.75Ga0.93Si0.07 alloy are presented in the cast state and in the state after multi-axial isothermal forging (MIF) at 700°C and true degree of deformation e = 3.19. It is shown that as a result of MIF, the initial equiaxed microstructure is transformed into a bimodal one in which large grains 100–200 μm in size are surrounded by a layer of fine-grained microstructure.As a result of MIF, the range of martensitic transformation is slightly shifted to the region of low temperatures by about 5°C. The analysis of phase transformations in the region of room temperatures shows that the intervals of martensitic and magnetic phase transformations are superimposed on each other. The MCE value in a magnetic field of 1.8 T is 0.59ºC in the initial cast state, and as a result of forging it decreases to 0.55°C.
Functionalities of Ni–Ti Shape Memory Alloys and Their Efficiency as Event Actuators of Microelectromechanical Systems
Authors: Kalashnikov V. S. , Koledov V. V. , Shavrov V. G. , Andreev V. A. , Nesolenov A. V. , Kuchin D. S. , Karelin R. D.
Published: April 2024

The functionalities of Ni–Ti alloys subjected to different deformation treatments are studied. A critical stress corresponding to the onset of degradation of the functional properties were determined; it was found that this stress is about twice as low as the yield stress. The efficiency coefficients of virtual thermodynamic machines with a working body made of the investigated materials were calculated and compared with the efficiency of a Carnot engine based on the same materials; the ideality factor has been calculated under the condition of actuating at stresses no higher than critical ones. It has been established that, at the single actuation, the highest ideality factor (9.7%) is characteristic of a material consisting of bars 20 to 5 mm in diameter obtained by warm forging at 350°C. It has been determined that, at discontinuous operation under stresses lower than the critical ones by a factor of 1.2, the ideality factor is 7.4–7.7% for alloys subjected to hot forging or equal channel angular pressing combined with warm forging.
Thermal Contact Resistance at Cryogenic Temperatures in the Presence of Strong Magnetic Fields
Authors: Kolesov K. A. , Mashirov A. V. , Kuznetsov A. S. , Koledov V. V. , Petrov A. O. , Shavrov V. G.
Published: April 2024

A physical model of a mechanical thermal switch at cryogenic temperatures is studied. In the model, heat is transferred due to contact heat conduction in a detachable contact pair of two copper cylinders. A mechanical thermal switch is developed using a cryomagnetic system with a 10-T superconducting solenoid, and the values of thermal contact conductance are determined in a temperature interval of 10–160 K, including values at a magnetic field of 5 T. In an experimental temperature interval of 60–80 K, close to the phase transition of the DyAl2 and GdNi2 compounds, the thermal contact conductance is 2300–3300 W/(m2 K). The effect of magnetic field of up to 5 T on thermal contact resistance is experimentally determined under vacuum conditions
Cascading of Three-Conductor Modal Filters Based on Asymmetric Coaxial Structures and the Microstrip Line
Authors: Belousov A. O.
Published: April 2024

A possibility of improving protective characteristics of transmission lines by cascading of multiconductor modal filters (MFs) with different geometric configurations is studied. Three-conductor MFs based on an asymmetric coaxial structure and a microstrip line and four variants of cascade structures consisting of two and three sections of such MFs are considered. Simulation of the time response to an ultrashort pulse (USP) and parametric optimization are performed. Attenuation of USP by a factor of 27.4 is achieved.
Derivation of Relationships of Currents in External Circuit and Parameters of Sampl
Authors: Dmitriev S. G.
Published: April 2024

Several methods to derive relationships between currents in the external circuit and variations in parameters of samples that induce such currents are considered. The relationships generalize the Shockley–Ramo theorem and may serve as a development of Kirchhoff laws for electrical circuits.
Development and Synthesis of Analog Devices on Elementary Units
Authors: Mart’yanov P. S.
Published: April 2024

The technique for synthesis of analog devices with the use of elementary units of electronics, such as integrating, differentiating, adding (subtracting), multiplying (dividing), and multiplexing (demultiplexing) elements, is described. The proposed technique of synthesis is justified theoretically and the elementary units used are called the proposed element base of analog electronics. The description of the theory, as well as an example of developing a model of an analog low-pass filter with the use of the proposed technique, arepresented.
General Solution of the Problem of Synthesis of a Geodesic Lens with Central Symmetry and Dielectric Filling
Authors: Venetskiy A. S. , Kaloshin V. A. , Thang Chan Tran
Published: April 2024

A solution is obtained for the problem of synthesis of a metal–dielectric geodesic lens with central symmetry and, in the general case, inhomogeneous dielectric filling, which transforms the field of a point source into a given geometric optical field. By way of example using the obtained solution, the problems of synthesis of a geodesic lens antenna with layered and gradient dielectric filling are considered. In particular, solutions are obtained for lens antennas with in-phase output front and out-of-phase front that forms a tableshaped radiation pattern. The solutions are analyzed with the aid of numerical simulation using the finite element method.
Spectral Parameters of Signal in a Meteorological Radar
Authors: Denisenkov D. A. , Zhukov V. Yu. , Shchukin G. G.
Published: April 2024

Specific features of the application of the spectral parameters of the received signal for the recognition of dangerous weather phenomena in a meteorological radar are considered. The advantages and disadvantages of existing methods are outlined. A new recognition method based on the estimation of the base of the input random process is proposed.
Implementation of the Maximum Bandwidth Ratio of Satellite Radio Communication Systems under the Conditions for Intramodal Dispersion of Transionospheric Radio Channels
Authors: Ivanov D. V. , Ivanov V. A. , Ryabova N. V. , Kislitsyn A. A.
Published: April 2024

The problem of significant extension of the band of the transionospheric radio channel to the maximum possible values is solved to improve the efficiency of satellite communication systems. Hardware and software are created to suppress the group delay dispersion using methods of data mining for experimental diagnostics of a transionospheric communication line. Algorithms and tools for intelligent sensory diagnostics of wideband radio channels with adaptation to dispersion variability are developed. In the absence of adaptation, it is possible to create radio channels of undistorted transmission with a bandwidth ratio of no greater than 4.5%, while adaptation to dispersion variability makes it possible to increase the bandwidth ratio to 11.5%. The greatest bandwidth ratio (20–25%) for dispersion-free transmission can be achieved with the aid of adaptive inverse filtering of the channel frequency response in combination with such intelligent methods as equalization with error, machine learning of channel equalizer, and big data processing.
Mathematical Modeling of the Amplitude, Angular, and Time Characteristics of Short Radio Waves in Slightly Oblique Sounding of the Ionosphere
Authors: Kryukovskii A. S. , Lukin D. S. , Mikhaleva E. V. , Rastyagaev D. V.
Published: April 2024

The method of bicharacteristics is used to study the propagation of decameter radio waves in the ionosphere containing the E, F1, and F2 layers and a traveling ionospheric disturbance (TID) upon slightly oblique sounding with frequency-modulated signals. The propagation of both ordinary and extraordinary waves is considered, the ionograms are compared, and their relative shift is studied. The structure of ionograms in the vicinity of caustics, which appear at the reception point at frequencies reflected in the vicinity of the E layer and TID, is studied. The divergence of the ray flux at the point of radiation reception, which determines a decrease in the amplitude, is calculated.
Microstrip diagram generating circuit for sector formation linear array element radiation patterns
Authors: Bankov S. E. , Frolova E. V.
Published: April 2024

A microstrip pattern-forming circuit designed to form sector radiation pattern of a linear antenna array. Proposed approximate method of device synthesis, including analysis of an infinite periodic system of related microstrip lines. Based on the found generalized parameters of the structure, the design was selected tive parameters of the circuit. Its electrodynamic analysis was carried out in the HFSS system, calculated in frequency band, the amplitude-phase distribution formed in the output channels. Designed, a sample device was manufactured and experimentally studied, providing in the frequency band up to 80% formation of the required amplitude-phase distribution. Based on received experimental data in the HFSS system, modeling of the diagram-forming scheme was carried out we are with a linear array of horns and it is shown that the elements of such an array have diagrams on straightness close to rectangular.
Frequency-Separating Devices for Secondary Surveillance Radar Systems
Authors: Suchkov A. V.
Published: April 2024

A frequency-separating device (FSD) with low insertion losses has been developed that provides electrical strength at high input power and combines the functions of several typical elements of the feeder path of a secondary surveillance radar (SSR): a receive/transmit switch, a harmonic filter, and a receiving band-pass filter. The issues of synthesis, analysis, and optimization of filters for the receiving and transmitting channels of the FSD are considered. Two options for the implementation of an FSD with insertion loss in the channel bandwidths within 0.7 dB, a harmonic suppression level of more than 40 dB, channel isolation, and attenuation at a deviation of ±60 MHz from the center frequencies of the passbands of at least 50 dB are proposed, the devices operate at frequencies of the FSD and of the seventh range of SSR systems with input pulse power up to 12 kW. The main dimensions of the FSD design, the results of numerical simulation, and the data of experimental verification of the characteristics are given. A comparative analysis of theoretical and experimental results is given.
Application of the 2D Code Tamic Analyzer Based on the Method of Impedance Analog of the Sestroretskii Electromagnetic Space for Problems of Plasma Diagnostics in Tokamak Fusion Facilities
Authors: Vershkov V. A. , Shelukhin D. A. , Isaev M. Yu. , Klimov K. N.
Published: April 2024

Applications of the two-dimensional full-wave electromagnetic code Tamic Analyzer, developed by B.V. Sestroretskii to study the limiting possibilities of diagnostics of reflectometry in tokamak plasma. It is shown that by comparing experimental reflectometry data with calculations using this code, it is possible to determine the structure of density fluctuations in a tokamak, but the experimental radial correlation lengths can be significantly overestimated. Simulation using the Taimic Anylyser code made it possible to determine the limiting level of density fluctuations at which it is possible to measure the plasma density profile and observe Alfven fluctuations in the International Experimental Thermonuclear Reactor of the tokamak type (ITER) under construction. Possible ways to increase the speed and counting field of the code are considered.
The Franz-Keldysh effect in silicon–ultrathin (3.7 nm) oxide–polysilicon structures
Authors: Belorusov D. A. , Goldman E. I. , Chucheva G. V.
Published: April 2024

The manifestation of the Franz–Keldysh effect was discovered when illuminated by indirect daylight Al–n+-Si:P–SiO2–(100) n-Si structures with ultrathin (3.7 nm) oxide. It has been shown that the use of backlight even at low field voltages (up to 3 V) leads to an increase in the tunneling current through the oxide compared to the current in darkness by three orders of magnitude. A model of the influence of radiation on the process of electron tunneling through an ultrathin insulating layer has been constructed. At first as a result of the Franz–Keldysh effect, a radiation quantum is captured by an electron and this charge carrier tunnels through the barrier at a higher level compared to darkness. After a charge carrier enters a semiconductor, its energy is sufficient for several events of electron–hole pair production during impact ionization of silicon.
Investigation of superconducting transmission lines and tunnel junctions for detecting signals at frequencies above 1 THz.
Authors: Kinev N. V. , Chekushkin A. M. , Khan F. V. , Rudakov K. I.
Published: April 2024

Superconducting integrated circuits based on NbTiN/Al transmission lines at frequencies up to 1.1 THz have been developed and experimentally studied. Numerical modeling of two microcircuit topologies with an operating frequency range of 0.9…1.2 THz, containing a slot antenna, made in a thin NbTiN film and matched in output to a microstrip transmission line, and a tunnel junction of the “superconductor–insulator–superconductor” (SIS) type with an area of the order of 1 μm^2, acting as a terahertz detector. Experimental samples of the microcircuit were manufactured and tested; in the experimental setup, a backward wave lamp (BWL) with an output frequency of up to 1.1 THz was used as a source. A powerful pumping of the SIS detector was obtained, thereby demonstrating the applicability of the manufactured NbTiN/Al transmission lines for operation in superconducting circuits at frequencies above 750 GHz, where traditionally used Nb/Nb transmission lines do not operate due to high attenuation.
Magnetron deposition of barium hexaferrite films from a target of stoichiometric composition
Authors: Luzanov V. A.
Published: April 2024

A technique has been proposed for obtaining films of barium hexaferrite on sapphire with the (0001) orientation using the high-frequency magnetron sputtering of a stoichiometric BaFe12O19 target followed by annealing The performed X-ray diffraction analysis and Raman spectrometry showed the possibility the possibility of crystallization of oriented films without using correction of the target composition.
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Authors: Nazarov L. E.
Published: April 2024

A description of the algorithm for optimal symbol-by-symbol reception of signal structures based on block noise-resistant codes in non-binary Galois fields is given. It is shown that the basis of this algorithm is the fast spectral transformation algorithm in the Walsh–Hadamard basis with the dimension of the Galois field. It is shown that the resulting complexity of the analyzed character-by-character reception algorithm is determined by the dimension of the dual code, which determines the prospects of its application for block noise-resistant codes with a high code rate (with low redundancy). The results of modeling a character-by-symbol reception algorithm are presented in order to study noise immunity for a number of frequency-efficient digital signals with quadrature-amplitude and amplitude-phase manipulations (with frequency coefficient efficiencies of 3, 4 and 6 bps/Hz) in combination with a parity check code. It is shown that the use of a symbol-by-symbol reception algorithm provides an energy gain of up to 1.5...3.0 dB in relation to the transmission and reception of the considered series of signals without coding.
Technology of experiments on non-thermal effects of powerful
lectromagnetic pulses on natural and artificial environments
Authors: Vdovin V. A. , Denisov R. A. , Sapetckii S. A. , Cherepenin V. A.
Published: April 2024

The features of the technology of experiments on the non-thermal effects of high-power nanosecond pulses are considered using the example of a setup used to modify biological media and other objects with heterogeneous electrophysical characteristics. An experimental setup has been created to study the non-thermal effects of high-power pulses on samples of various materials, which generates pulses with a repetition frequency of up to 500 Hz, amplitude up to 60 kV and duration 5 ns. Simulation of transient processes in the equivalent electrical circuit of the load was carried out, and a biological one was used as a load material placed in a microplate.
Influence of feedstock on the properties of LuAG:Cr^4+ ceramics.
Authors: Lopukhin K. V. , Balashov V. V. , Kozlova S. M. , Kanaev A. Yu. , Efimov A. A. , Faikov P. P.
Published: April 2024

Samples of Cr^4+:LuAG ceramics were obtained using commercial and reprecipitated Lu_2O_3 powders. The optimal conditions for the synthesis of reprecipitated Lu_2O_3 powder were determined, a dilatometric analysis of the ceramics was carried out, and the influence of the original Lu_2O_3 powder on the optical properties of ceramics.
A fast and efficient approach for calculating electric fields with application to topology optimization of microdevices.
Authors: Minin Iu. B.
Published: April 2024

A new numerical approach is proposed for fast and efficient calculation of electric waves, passing through wave microdevices using the Helmholtz equation. The efficiency, speed and accuracy of this approach are investigated.
Fiber refractometer for monitoring the vital activity of microalgae.
Authors: Sudas D. P. , Kuznetsov P. I. , Golant K. M.
Published: April 2024

The possibility of assessing the influence of external conditions, such as glucose content in solution and external lighting, on life activity has been shownblue-green algae with control mode real time. Using fabricated fiber sensors, the time dependence, lasting more than 40 hours, and changes in the refractive index of a suspension containing microalgae Chlorella Vulgaris during their life activity were studied.
Comparison of a Genetic Algorithm and Evolutionary Strategies in Optimization of Strip-Structure Modal Filters
Authors: Belousov A. O. , Gordeeva V. O.
Published: April 2024

The features arising from the optimization of strip modal filters (MFs) using a genetic algorithm (GA) and evolutionary strategies (ESs) are considered. Sequential optimization of microstrip MFs and MFs with broad-side coupling was performed according to the criterion of minimizing the maximum amplitude of the output voltage. The results of such optimization with different numbers of calculations are presented, including the values of the optimized parameters, the objective function, the time spent on the calculation, stopping criteria (when optimized by ESs) and the voltage waveforms at the output of the studied MFs. A detailed analysis of the results of the two algorithms is presented. The advantages and disadvantages, as well as differences in the operation of each algorithm, are determined using the example of optimization of two MFs.