bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessment of Carbon Stock and СO2 Production Potential for Soils of Coniferous-Broad-Leaved Forests
Authors: Ryzhova I. М. , Podvezennaya М. А. , Telesnina V. М. , Bogatyrev L. G. , Semenyuk О. V.
Published: April 2024

Within the territory of MSU Agrobiostation “Chashnikovo”, assessment of carbon stock for soil, typical for coniferous-broad-leaved forests subzone – coniferous forests, small-leaved forests, agrocenoses, fallow lands and floodplain meadows – was given. The next indexes were studied for litters: typology, stock, detritus content and ratio of sub-horizons thickness (deposit) – these indexes are indicators of organic matter decomposition intensity. For mineral soil profile, the assessment of general organic carbon stock in 0–30 and 0–100 cm layers, as well as stock of biologically active carbon in 0–20 cm layer (by calculation according to the content of total carbon), are given. Maximum organic matter accumulation in litters and moderate accumulation – in mineral profile, was obtained for coniferous forests soddy-podzolic soils. The litter carbon stock value in spruce forests differ by almost 10 times, depending on location in tessera. Minimal carbon accumulation by litters is obtained for meadow ecosystem soils – upland meadows as well as flood-plain meadows. Alluvial soils of flood-plain meadows are characterized by highest stock of general carbon, as well as carbon of biologically active soil organic matter. Potential of CO2 production by soil, determined by data, including structural and functional litter indexes and organic matter biologically active carbon stock (0–20 cm layer), depends on combination of row of factors: vegetation type, hydromorphism degree, and agricultural use character in present or past. Coniferous forest soils comparing with small-leaved forest soils are characterized by less rate of litter decomposing due to plant remains biochemical features, thereby these soils are assumed to less CO2 production potential. Soils of natural grass ecosystems, especially flood-plain meadows, are characterized by maximal potential production of carbon dioxide, resulting from intensive plant residues decomposition and high stock of biologically active organic matter carbon.
Soil Formation Features in Drained Lake Basins of the Bolshezemelskaya Tundra
Authors: Kaverin D. A. , Deneva S. V. , Pastukhov A. V. , Yаkubenko S. V.
Published: April 2024

The features of the structure, properties, and temperature regimes of soils functioning in two different drained lake basins of the Bolshezemelskaya tundra are characterized. The basins differ significantly in the features of landscape development, the composition of bottom (soil-forming) sediments, and the patterns of the soil and vegetation cover. In a naturally drained basin composed of mineral (sandy and clayey) bottom sediments, soils belonging to the departments Gley, and Poorly developed are formed, which are typical for the watershed landscapes of the region. Soils function as ecosystem-modified permafrost-affected profiles, partially protected from thaw. The soil profile is acidic, not saturated with bases, with moderate carbon content in the mineral horizons. In the artificially drained basin, covered with a layer of silted peat, predominantly peaty permafrost-affected soils were formed, including peat soils of tundra meadows, which are unique for the landscapes of the Bolshezemelskaya tundra. Peaty soils of the basin appear to be as ecosystem-protected, i.e. protected from thawing, and they are characterized by high ash content and slightly acidic reaction. A significant differentiation of the studied soil parameters are determined by different basins, which are different according to the composition of parent sediments, the specifics of landscape development, and manifestations of present-day cryogenic processes.
Soil Respiration and Carbon Sequestration
Authors: Kudeyarov V. N.
Published: April 2024

An increase in the concentration of carbon dioxide in the atmosphere is a trigger for the activation of all processes of the carbon cycle, including soil respiration (SR), since it causes not only an increase in the greenhouse effect of the atmosphere, but also its fertilization. The consequence of fertilization is the tendency to increase the world’s net primary production of photosynthesis (NPP) and heterotrophic respiration of soils (RH). The increase in global terrestrial carbon sink was accompanied by an increase in CO2 in the atmosphere. The global increase in RH is due to global losses of soil organic carbon and is confirmed by models according to which the average residence time of organic carbon in the soil pool has decreased by 4.4 years over the past century. To assess the level of C sequestration in soils, it is necessary to determine the balance between the RH of the soil and the amount of new soil C-sink in the form of net biome production (NBP) – resistant to mineralization. Carbon sink into net ecosystem production (NEP) determines short-term unsustainable carbon sequestration.
Hypersonic Nonequilibrium Flow around Sharp Edge
Authors: Ankudinov A. L.
Published: April 2024

A regularized problem has been formulated to describe the flow of a molecular gas in a hypersonic macrokinetic nonequilibrium thin viscous shock layer (kinetic TVSL) near a sharp edge. It is shown that the solution of the regularized kinetic TVSL problem on the sharp edge, the description of friction and heat transfer coincides with the solution of the Navier–Stokes analogue of this TVSL problem.
It is shown that in the kinetic TVSL the friction stress and the normal heat flow on the wall in the vicinity of the sharp edge are identical with the corresponding values in the Navier–Stokes TVSL. The similarity of currents near the sharp edge in the kinetic and Navier–Stokes versions of the TVSL is indicated. A method for constructing a solution to the kinetic TVSL problem for the vicinity of a sharp edge based on the Navier–Stokes TVSL solution is indicated. A formula is obtained for calculating the pressure on the surface in the kinetic TVSL flow near the sharp edge through the components of the solution (on the wall) of the Navier–Stokes TVSL flow problem.
Doubly Periodic Contact Problems for a Layer with an Unknown Contact Zone
Authors: Zolotov N. B. , Pozharskii D. A.
Published: April 2024

Doubly periodic contact problems are considered for a layer with an unknown contact domain. One face of the layer is subjected to sliding support or rigidly fixed. The problems are reduced to integral equations the kernels of which do not contain integrals. For full contact of the other layer face with a two-dimensional sinusoidal rigid surface, the problems have exact solutions used to verify computer programs realizing the numerical method of Galanov nonlinear integral equations which allows us to determine the contact domain and the contact pressure simultaneously. Mechanical characteristics are calculated for indentation of the system of elliptic paraboloids, the passage from discrete to continuous contact zones is investigated.
Investigation of a Thermal Detonation Wave in a Mixture of Water Drops with Molted Lead
Authors: Melikhov V. I. , Melikhov O. I. , Bashar Saleh
Published: April 2024

The patterns of the wave of thermal interaction of water drops in a high-temperature molten lead, are studied. Due to the boiling of water on the surface of molten lead, both liquids (phases) are separated by a vapor film. A one-dimensional model of interacting and interpenetrating continuums is used, which describes the dynamics of each fluid by introducing a special field characterized by its own velocity, temperature, and volume fraction. Wave velocity is determined by the equality of phase velocities and temperatures in the Chapman-Jouguet plane. The parameters at the pressure peak are calculated from the conditions at the discontinuity which are the boundary conditions for integrating the conservation equations in the zone of interaction of water droplets with the melt. The resulting structure of the thermal detonation wave is characterized by the fact that the maximum pressure is at some distance from the shock wave.
Wave Motion in a Surface Electric Charged Viscous Homogeneous Liquid
Authors: Ochirov A.A. , Chashechkin Yu. D.
Published: April 2024

The influence of the surface electric charge on the character and properties of wave motion along the free surface of a viscous homogeneous liquid has been investigated by analytical asymptotic methods. Expressions describing the dispersion dependences of the wave motion components are obtained. The phase and group velocities of the structures forming the wave motion are determined.
High-Accuracy Numerical Schemes for Solving Plane Boundary Problem for a Polyharmonic Equation and Their Application to Problems of Hydrodynamics
Authors: Petrov A.G.
Published: April 2024

Boundary value problems are considered for harmonic, biharmonic equations, as well as the general polyharmonic equation for multiply connected domains on the plane. The problems are reduced to solving linear integral equations on boundary contours, which are assumed to be smooth. An algorithm for deriving an approximation of integral equations by a linear system is presented, taking into account the logarithmic singularities of the kernels of integral operators, through which integral equations are expressed. The algorithm uses the periodicity of functions defined on closed boundary contours. As the number of grid points increases, the approximation error decreases faster than the grid spacing to any fixed degree. Applications to solving problems of hydrodynamics, filtration and other problems of theoretical physics are considered.
Limited and Smooth Controls of Oscillations in Systems Given by Differential and Integro-Differential Equations
Authors: Bobyleva T. N. , Gusev I. M. , Shamaev A. S.
Published: April 2024

The paper considers the problem of damping vibrations of a membrane and a plate with the help of forces distributed over their entire area. The proposed method allows us to consider restrictions not only on the absolute value of the control, but also on the absolute value of the derivatives of the functions that specify the control. Sufficient conditions are given for the initial conditions under which the problem of bringing the system to rest in a finite time is solvable, and the time of bringing to rest is estimated.
Using the Accelerated Convergence Method for Solving the Singular Sturm–Liouville Problem
Authors: Nesterov S. V.
Published: April 2024

This article is dedicated to the memory of L.D. Akulenko, with whom the author of the article worked for more than 40 years. Within the framework of the accelerated convergence method developed jointly, a number of classes of problems related to the Sturm–Liouville problems were solved. Based on the research results, several dozen articles and a generalizing monograph [1] were published. In this paper, we describe the adaptation of the method to solving singular Sturm–Liouville problems.
Motion of a Variable Body with a Fixed Point in a Time-dependent Force Field
Authors: Burov A. A.
Published: April 2024

The problem of motion around a fixed point of a variable body in a time-dependent force field is considered. The conditions under which the equations of motion are reduced to the classical Euler–Poisson equations describing the motions of a rigid body in the field of attraction are indicated. The problems of the existence of the first integrals and the stability of steady motions are discussed.
Effect of Surface Tension Relaxation on the Stability of the Charged Jet
Authors: Grigoryev A. I. , Kolbneva N. Yu. , Shiryaeva S. O.
Published: April 2024

In the asymptotic calculations of the first order of smallness by the dimensionless amplitude of capillary waves on the surface of charged jets of polar liquid, the effect of the relaxation effect of surface tension on the regularities of their implementation is investigated. Calculations are carried out on the model of an ideal non-compressible electrically conductive fluid. It has been shown that taking into account the effect of dynamic surface tension leads to an increase in the order of the dispersion equation, which has another damping root, which is obliged to destroy the near-surface double electric layer (destruction of the ordering of polar molecules in the near-surface layer), which undergoes electrostatic instability at sufficiently large charges (pre-breakdown in the sense of ignition of corona discharge in air). In the ideal fluid mathematical model used, the relaxation motion of the jet surface disturbances that occurs when the surface tension relaxation effect is turned on and the attenuation decrements of capillary wave motions are purely of a relaxation nature.
Natural Vibrations of a Gas in a Helmholtz Resonator with a Periodically Varying Cross-section
Authors: Ko Ko Phyo
Published: April 2024

Within the framework of the long-wave approximation, the frequencies and shapes of gas natural oscillations in a Helmholtz resonator having the shape of a pipe of periodic cross-section have been studied. The problem is reduced to the Sturm–Liouville problem with boundary conditions of the first kind, the solution of which is carried out by the method of accelerated convergence. A detailed analysis of the dependences of eigenvalues and eigenfunctions on pipe parameters was carried out. A “self-similar” type of dependence of the natural frequency for various modes has been revealed. The values of the resonator periodicity parameters at which a sharp change in the natural frequency occurs are determined.
Gas-Phase Conversion of Cation-Exchange Resin KU-2×8-M (M = Cs, Ni, Cu, Fe, Nd, U) in a Nitrating Atmosphere
Authors: Kulyukhin S. A. , Gordeev A. V. , Seliverstov A. F. , Kazberova A. Yu. , Kostikova G. V. , Krasavina E. P. , Nevolin Yu. M.
Published: April 2024

A new approach to the destructive processing of the cation-exchange resin KU-2×8-M (M = Cs, Ni, Cu, Fe, Nd, U) based on its gas-phase treatment in a nitrating atmosphere with subsequent chemical treatment of the conversion products is considered. It is shown that exposure of KU-2×8-M samples (M = Cs, Ni, Cu, Fe, Nd, U) in an HNO3(vapour)-air atmosphere at temperatures of 403-443 K for 8 and 24 h followed by dissolution conversion products in 0.5 mol∙L-1 NaOH and ozonation of the resulting solutions allows e cient utilization of the KU-2×8-M resin (M = Cs, Ni, Cu, Fe, Nd, U).
On global 137cs di usion in bottom sediments of northern seas
Authors: Bakunov N. A. , Bolshiyanov D. Yu. , Aksenov A. O. , Makarov A. S.
Published: April 2024

In bottom sediments of the Laptev and the Kara seas 137Cs has been migrating with di usion coe cient ( D ) n ·(10-9-10-8) cm2/s during nearly 30 years. In the sediments pro le 137Cs concentration gradient was persisting between the layers. The trend of concentration decrease from the upper to the lower layers of the core was not violated along the entire path of radionuclide migration. 137Cs has been migrating in bottom sediments slowly; nearly 20% of the radionuclide stayed in the upper (0-1 cm) layer. In the Tsivolki Bay of Novaya Zemlya Archipelago 137Cs has been migrating in very low temperature conditions of water and bottom sediments (-1.0, -1.2°С). 137Cs concentration in the upper layer of the Laptev Sea and Tsivolki Bay sediments was characterized by close values, 7-18 and 14-24 Bq/kg, which correlate with global level of sediments contamination. The Tsivolki bay is ice-covered for 10 months. 137Cs pro le in the cores was forming due to radionuclide di usion in conditions of short warm period of terrigenic sedimentation. 137Cs concentration in the bay sediments and a type of the concentration pro le demon rated an absence of radionuclide release from buried radioactive objects in the bay. 137Cs di usion coe cients de nition computed with experimental data will be necessary in radionuclide migration models and scienti cally supported measures of damage minimization from exposure to the radiation factor.
Comparative analysis of UN and UO2 oxidation in air and nitrogen hemioxide
Authors: Volgin M. I. , Kulyukhin S. A. , Nevolin Yu. M.
Published: April 2024

Oxidation of UO2 and UN by atmospheric oxygen and nitrogen hemioxide, which is a hard-to-localize greenhouse gas, was investigated by thermal analysis. For oxidation, mixtures of N2O-N2 and O2-N2 were used with a volume fraction of the oxidizing agent of 20%. For UO2 and UN, the phase composition of the nal oxidation product in air and in N2O is the same and is U3O8. In both cases, N2O behaves as a milder oxidizing agent compared to atmospheric oxygen. Oxidation of UO2 and UN in a ow of N2O begins at a temperature 180 and 70°C higher than in air, respectively. The oxidation of UN in a ow of N2O proceeds in three stages. At the rst stage, the reaction products are UO2 and U2N3; UO2 is the product of the second stage; and at the third age U3O8 is produced. No pronounced staging is observed in the process of UO2 oxidation. The possibility of utilizing nitrogen hemioxide when it is used in the process of voloxidation (oxidation) of spent nuclear fuel is shown
Study of the chemical stability of Sr0.5Zr2(PO4)3  phosphate with a cosnarite structure in various environments
Authors: Alekseeva L. S. , Nokhrin A. V. , Orlova A. I. , Boldin M. S. , Voronin A. V. , Murashov A. A. , Chuvil'deev V. N.
Published: April 2024

Samples of ceramics based on Sr0.5Zr2(PO4)3 phosphate with the structure of the kosnarite mineral (NaZr2(PO4)3, NZP) were obtained by electric pulse plasma sintering. Submicron phosphate powders with particle sizes less than 1 μm were obtained by the sol-gel method. Powders and ceramics have a single-phase NZP structure. The relative density of the ceramics was 97.6%. The chemical stability of the obtained ceramics was studied in static mode at 90°C in distilled and mineral water and in acidic and alkaline environments. The minimum achieved leaching rates were ~10-4-10-6 g/(cm2 day). The in uence of the contact environment on the rate and mechanism of Sr leaching from Sr0.5Zr2(PO4)3 ceramic samples within 42 days was studied. It has been shown that Sr leaching occurs due to the dissolution of the surface layer of ceramics when tested in distilled water and in mineral water (up to 7 days) and due to Sr leaching from the open ceramic surface after 7 days of testing in mineral water.
Analysis of a Passive Current-Controlled Frequency Mixer
Authors: Korotkov A. S. , Chan T. D.
Published: April 2024

The paper presents a generalized technique for calculating a passive current-controlled frequency mixer at an arbitrary intermediate frequency, taking into account the complex input impedance of the current source and output load. The results of simulation in the Micro-Cap environment and comparison with thecalculation are presented. The frequency dependences of the transfer impedance are considered.
The Composite Radio Absorbing Material Based on Resistive Rings
Authors: Ponomarenko V. I. , Lagunov I. M.
Published: April 2024

The frequency dependences of the effective permittivity of the structure in the form of an array consisting of ring resistive elements that are located in a dielectric layer are obtained. The calculations are based on the solution of the problem of diffraction of an electromagnetic wave normally incident on the structure. The possibility of variation of the dispersion dependences in wide limits by means of changing the structureparameters is shown.
“Superlight” Propagation of Electromagnetic Pulses
Authors: Strelkov G. M. , Khudyshev Yu. S.
Published: April 2024

Based on the calculation of the Fourier integral directly and without simplifying assumptions, the analysis of the process of passage of terahertz pulses with a hat-shaped envelope and Van Bladel envelope through a layer of a resonant-absorbing medium described by the Drude–Lorentz model is carried out. It isshown that until the end of the time interval prescribed by the Maxwell equations, there is no radiation at the exit from the layer, i.e., the Fourier integral does not contain the effect of “superluminal” propagation of anelectromagnetic pulse through a resonantly absorbing medium. An alternative interpretation of the shift to the beginning of the pulse of the envelope maximum emerging from the radiation layer at small optical depths(~1) of the layer at the resonant frequency of the medium is proposed.
Effect of Elastic Resonances of Substrate on Ferromagnetic Resonance in Yttrium Iron Garnet Films
Authors: Vetoshko P. M. , Vlasov V. S. , Shavrov V. G. , Shcheglov V. I.
Published: April 2024

The problem of excitation of ferromagnetic resonance in a thin ferrite film with magnetoelastic properties located on a thick elastic substrate is considered. A model is proposed for the excitation of elastic modes in the substrate due to the propagation of a periodic boundary regime created by magnetic oscillations in the film. The conditions for stationary oscillations are used to obtain the frequency response characteristics of ferromagnetic resonance, which exhibit strong oscillations due to the excitation of high-order elastic modes over the thickness of the substrate.
Density Parameters of the Probability Distribution of Fluctuations of the Apparent Center of Radiation from the Helicopter Propeller Bushing during its Radar Observation
Authors: Stepanov M. A.
Published: April 2024

The properties of angular noise of radar reflections from the rotor head are considered. On the basis of a multipoint geometric model of the rotor head, analytical expressions are obtained that allow calculating the parameters of the probability distribution density of angular noise for the azimuth planes and the elevation of the rotor head of a single-bladed screw at an undirected angle of the control sleeve. Correlation obtained for one blade rotor head is generalized to thease of a rotor head with an arbitrary number of blades. It is shown that the rotor head angular noise is a random process with periodically changing parameters. The theoreticalresults are confirmed by mathematical modeling.
Application of Heat Treatment to Optimize the Magnetostrictive
Authors: Ivasheva E. E. , Leontiev V. S. , Bichurin M. I. , Koledov V. V.
Published: April 2024

The heat treatment effect of the magnetostrictive component in magnetoelectric (ME) composites consisting of a piezoelectric and magnetostrictive material has been studied. The dependence of the ME voltage coefficient on frequency was experimentally found without heat treatment and with annealing from 200 to 500°C of the AMAG493 amorphous alloy, which acted as a magnetostrictive component. It is shown that with an increase in the processing temperature of an amorphous alloy, an increase in the ME voltage coefficient is observed: the maximum value of the ME coefficient was observed at a temperature of 350°C and amounted to 29.52 V cm–1 Oe–1 at a resonance frequency of 54 kHz. It has been proven that the increase in the ME voltage coefficient occurs due to the improvement in the characteristics of the amorphous alloy during heat treatment, which leads to partial nanocrystallization of the material.
Magneto-Optical Visualization of Magnetic Phases in an Epitaxial Film of Ferrite–Garnet Near the Compensation Point
Authors: Vetoshko P. M. , Berzhanskii V. N. , Polulyakh S. N. , Suslov D. A. , Mashirov A. V. , Shavrov V. G. , Pavlyuk E. I.
Published: April 2024

A method for the magneto-optical visualization of magnetic phases in ferrimagnets in the vicinity of the compensation point in the lateral temperature gradient is described. On the example of films of bismuth–gadolinium ferrite garnet, zones corresponding to collinear and non-collinear magnetic phases were observed, depending on the temperature and the magnitude of the magnetic field in the range from 0 to 10 T.
Radio-Frequency System for Remote Monitoring of the State
Authors: Dorokhov S. P. , Reut V. R. , Prakhov A. S. , Ponomareva E. P. , Kuzhel M. P. , Kozlov V. A. , Badygeev A. A. , Andreichev S. S. , Koigerov A. S. , Salov A. S.
Published: April 2024

In this paper we present the results of the development of a radio-frequency system for remote monitoring of the state of protective containers with hazardous substances based on energy-independent transponders, which provide estimating the entire set of indicators of the state of the packaged cargo. The operating principle of the system is shown. The design of a transponder containing a radio tag based on surface acoustic waves using a multi-strip coupler, which provides switching signals from physical impact sensors, transmitting object identification data and reliable information about the current state of the product at the time of the survey, is considered. The experimental responses of the pulse responses of radio tags are presented. A practical implementation of a radio-frequency monitoring system that passed state tests is presented.
Effect of External Magnetic Fields on the Amplitude‒Time Characteristics of Penning Ion Sources
Authors: Maslennikov S. P. , Mamedov I. M.
Published: April 2024

The operation modes of pulsed Penning ion sources under the action of external magnetic fields corresponding to the operating conditions of geophysical well survey equipment are discussed. The obtained dependences of the amplitude‒time characteristics of the ion sources on the magnetic field value and configuration are reported. Based on the data obtained, options of neutron tube magnetic systems are proposed, which ensure an increase in the operation stability of neutron generators.
Analytical Formula for the Relation between the Experimental and Theoretical Parameters of the Tsallis Spectral Line
Authors: Mendelevich L. V. , Koksharov Yu. A.
Published: April 2024

An exact analytical formula is obtained that relates the experimental and theoretical parameters of the spectral line described by the Tsallis function, which includes the Gaussian, Lorentzian, line shapes intermediate between them, and super-Lorentzian as special cases. The procedure for the numerical calculation of the theoretical parameters of the line shape is studied by the example of electron spin resonance spectra. The effect of complicating experimental factors, including the noise and the analog signal digitization discreteness, on the accuracy of determining the theoretical Tsallian parameters is examined. It is shown that the proposed method for determining the theoretical parameters of the spectral line is not inferior in accuracy to the method for minimizing the root-mean-square error functional. It is predicted that the new approach can be used as an alternative to the available spectral line shape analysis techniques.
Optimal Discrete Estimation of Reference Points of a Discrete-Continuous Markov Process against the Background of Correlated Markov Noise
Authors: Detkov A. N.
Published: April 2024

In this paper, we solve the problem of synthesizing optimal and quasi-optimal algorithms for estimating the reference points of continuous components of a vector discrete-continuous Markov random process with allowance for the known statistical characteristics of additive Markovian correlated noise using the methods of the Markov theory of estimation of random processes. The method of difference measurements was used while synthesizing the algorithms. A block diagram of a quasi-optimal digital filter is given. Using a simple example, simulation shows the performance of a quasi-optimal algorithm in statistically uncertain situations.
Study of Ultra-High Frequency Radiometric Humidity Sounding of the Atmosphere for the Early Warning of Hazardous Weather Phenomena
Authors: Karavaev D. M. , Kuleshov Yu. V. , Shchukin G. G.
Published: April 2024

Ground-based microwave radiometry was used to study the characteristics of the moisture content of the atmosphere during the development of cloud-related hazardous weather phenomena, precipitation, and thunderstorms. On the basis of complex radiophysical studies of the atmosphere, carried out in the Leningrad oblast, the possibility of improving the methods of early warning of dangerous weather phenomena and diagnostics Ground-based microwave radiometry was used to study the characteristics of the moisture content of the atmosphere during the development of cloud-related hazardous weather phenomena, precipitation, and thunderstorms. On the basis of complex radiophysical studies of the atmosphere, carried out in the Leningrad oblast, the possibility of improving the methods of early warning of dangerous weather phenomena and diagnostics of atmospheric fronts with the involvement of operational microwave radiometric information is shown.
Suboptimal Algorithm for Measuring Pitch Frequency Using Discrete Fourier Transform of a Speech Signa
Authors: Savchenko V. V. , Savchenko L. V.
Published: April 2024

Starting from the definition of the main tone of the speaker’s speech as the minimum frequency of the linear power spectrum of the vocalized segments of the speech signal, an estimation of potentially achievable accuracy of its measurement under the action of background interference such as white Gaussian noise has been made. Based on this estimation, a suboptimal algorithm for measuring the pitch frequency using a short speech frame has been developed. The developed algorithm effectiveness is confirmed by the results of the experiment, during which the author’s software was used.
Multibeam Antenna with a Full Azimuth Field Angle Based on a Layered Metal-Dielectric Cylindrical Lens
Authors: Venetskiy A. S. , Kaloshin V. A. , Thang Tran  Tien
Published: April 2024

A multibeam antenna based on a layered lens with axial symmetry in the form of a set of dielectric disks with a refractive index gradient along the radius, which are located between metal disks, is proposed and investigated. A layered lens converts the fields of feeds located on a circle centered on the axis of the lens in the plane of its base into highly directed beams in the same plane. A synthesis of a layered lens is carried out, the layers of which are made in the form of a set of dielectric rings of variable thickness. The analysis of a multibeam lens antenna with metal-dielectric feeds was carried out by numerical simulation using the finite element method.
Radio Absorber with High Angular Stability of Resonance Frequency Based on Artificial Magnetic Conductor and Resistive Film
Authors: Kazantsev Yu. N. , Kraftmakher G. A. , Maltsev V. P. , Solosin V. S.
Published: April 2024

A structure of a radio absorber (RA) with a high stability of resonance frequency based on a resistive film with a sheet resistance of 120 Ω/sq and an artificial magnetic conductor in a pair of capacitive gratings on a dielectric layer with a high permittivity (epsilon_1 1) metallized on the opposite side is proposed. The results of numerical calculations of the frequency–angular dependences of the RA reflection coefficient confirm preliminary estimates obtained from analytical expressions. For example, at epsilon_1 = 20 , the shift of the resonance frequency is no greater than 2% at angles of incidence of phi=0^o...60^o , and the bandwidth-to-thickness ratio is 4.29 at phi=0.
Reducing the Energy Consumption of the Transmitting Active Phased Antenna Array of a Low-Orbit Communications Satellite
with a “Jumping” Beam
Authors: Anpilogov V. R. , Denisenkob V. V. , Levitan B. A. , Kozlov V. N. , Shitikov A. M. , Shishlov A. V.
Published: April 2024

The results of the analysis of the energy consumption of the transmitting active phased antenna array (APAA) of a spacecraft of the low-orbit communication system (with broadband access or with direct access to cellular subscribers) have been presented. It has been shown that in order to reduce energy consumption by switching on (off) the emitters, depending on the beam deflection angle from the nadir, it is possible to achieve a significant reduction in the heat release of the spacecraft’s APAA. But this solution is feasible only if the APAA forms one “jumping” beam.
Analysis of radiative absorption of acoustic Lamb waves in plates loaded with an inviscid non-conducting fluid.
Authors: Ageikin N. A. , Anisimkin V. I. , Voronova N. V. , Smirnov A. V.
Published: April 2024

The dependence of radiation losses into a liquid on the value of the displacement component U_3 normal to the plate on the surface of a piezoelectric plate was experimentally studied for Lamb waves of various orders. Waves whose phase velocity V_n in the plate are considered greater than the velocity of the longitudinal volumetric acoustic wave in the liquid V_l. It is shown that at small values of U3 there is no radiation into the liquid and the magnitude of radiation losses is close to zero even at V_n V_l; at large values of U_3, the magnitude of radiation losses is large and for Lamb waves in the YZ-LiNbO3 plate with a thickness normalized to the wavelength of 1.75 and frequency 16.97 MHz it reaches a value of 4 dB/mm, comparable to the radiative losses of surface acoustic waves in the same material.
Design of superconducting integrated matching structures.
Authors: Khan F. V. , Atepalikhin A. A. , Filippenko L. V. , Koshelets V. P.
Published: April 2024

Superconducting integrated structures intended for matching generator impedances based on a distributed Josephson junction and detector based on a superconductor–insulator–superconductor tunnel junction in the subterahertz frequency range. The structures were modeled using the transfer matrix method. The designs were calculated in a three-dimensional numerical modeling program. A qualitative agreement was found between the results obtained by the two methods. Three designs have been designed with various topologies covering the frequency range 250...680 GHz at a level of –2 dB
Structure of aluminum films for creating tunnel junctions.
Authors: Strelkov M. V. , Chekushkin A. M. , Lomov A. A. , Kraevsky S. V. , Fominskii M. Yu. , Tarasov M. A.
Published: April 2024

A series of studies of the structure of aluminum films deposited on single-crystalsilicon substrates in different temperature conditions. The roughness and grain size of films of nuclei 20 nm thick, deposited at elevated temperatures, and also dusted on top of the seed layer at room temperature to a thickness of 150 nm. The film profile was measured in an electron microscope. It was found that films on the hot sublayer turn out to be smoother, more rigid (less loose) and allow one to expect the creation of superconductor–insulator–superconductor and superconductor–insulator–normal metal transitions, respectively, with a higher current density and lower capacitance.
Development and research of a slow-wave system for a miniature W-band multibeam traveling wave lamp
Authors: Torgashov R. A. , Nozhkin D. A. , Starodubov A. V. , Ryskin N. M.
Published: April 2024

The results of the development of a meander-type slow-wave system (SS) with metal supports for a miniature high-power W-band traveling wave lamp (TWT) with two ribbon electron beams are presented. Using a three-dimensional finite element software package, the electrodynamic parameters of the GS were studied. A two-section model of a TWT amplifier with a discontinuity has been developed to prevent self-excitation. Three-dimensional modeling of electron-wave interaction was carried out. It was found that with a total beam current of 200 mA in linear mode, the gain exceeds 30 dB in the frequency band 95.4...97.75 GHz, and the output power in saturation mode reaches 120 W. A technology for manufacturing SS based on laser microprocessing of thin copper plates is proposed. Test samples of the SS were manufactured and verified using optical and scanning microscopy.
State and Stability of Forest Ecosystems of the Region with Extreme Anthropogenic Transformation (Evidence from the Oka River Basin)
Authors: Kolomyts E. G. , Sharaya L. S. , Sevostianov S. M.
Published: April 2024

Using satellite sounding data on the forest cover of Russia and three GIS programs, mapping of forest cover and average crown density in the Oka river basin was carried out. Considering hydro-ecological role of forests, these parameters were differentiated according to water management areas. The progressive decline in the wooded areas, thinning and defoliation of forest stands confirm the validity of classifying the Oka river basin as a territory with a catastrophic environmental situation. This is especially true for the forest-steppe zone, where the forest cover ranges from 2.4 to 40%. The average canopy density of the forests in the basin is 50.7%, which makes a significant part of them approaching the state of sparse hemi-xerophytic forests. Using the methods developed by the authors, the indices of the resistance and elastic-plastic stability of forests were calculated and the corresponding maps for the Oka river basin were constructed. It was found that the replacement of primary mixed and broadleaf forests with secondary small-leaved forests leads to a general increase in the dynamism of forest communities: to an increase in their sensitivity to disturbing signals and to an acceleration of ecogenetic successional changes that tend to transfer them to their previous (or new) stable state. The ordination of forest formations of the Oka river basin was carried out according to the gradients of the indices of resistance and elastic-plastic stability. The overwhelming majority of forest formations are characterized by high sensitivity to the initial signals of external disturbances, but at the same time, by sufficiently developed mechanisms of ecogenetic successions, which represent their elastic-plastic stability. This indicates the high reforestation potential of the degraded lands of the Oka basin, which makes it possible to include its forest areas in the global system of biosphere reserves. Two opposite mechanisms exhibiting the known buffer properties of the forest litter have been revealed. In response to the unfavourable impacts, the forest community switches from some leading processes of its functioning to others – from the level of autotrophic biogenesis to the level of detrital metabolism.
Stocks of Onobrychis (Fabaceae) Raw Materials in the Republic of Azerbaijan
Authors: Isaev J. I. , Jafarova Sh. B. , Мammadova N. H.
Published: April 2024

Abstract—The distribution areas and resources of Onobrychis Hill species (the sainfoins) in Azerbaijan were studied. The areas of thickets and the volumes of potential annual harvesting of 19 species, out of 22 common for Azerbaijan, were determined. It was found that sainfoins occupy an area of 1059.6 ha. The biological stock of the above-ground (herb and shoots) and underground (roots) parts in the studied areas is 291.133, 33.715 kg and 317.003 kg, respectively; the exploitable volume is 198.490, 22.371 kg and 214.834 kg, respectively; the potential volume of annual harvesting is 44.624, 14.321 and 5.593 kg of air-dry raw materials, respectively.
Resources of Melliferous and Polleniferous Plants of Central Asia and Kazakhstan Based on Melissopalynological Analysis
Authors: Kurmanov R. G.
Published: April 2024

Abstract—A palynological study of 82 samples of honey from Middle Asia and Kazakhstan was carried out in order to determine the resources of the key melliferous and polleniferous plants. The obtained results made it possible to establish 8 productive beekeeping zones in the studied territory. The most common pollen combinations are identified for each zone. The selected zones can be combined into two large groups: northern and southern, with a transitional area (zone 3, the Dzungarian Alatau mountain ridge) between them, where honey with mixed palynological characteristics is obtained. In the northern part, in zones 1 and 2 (northern and eastern Kazakhstan) Origanum vulgare L., Rubus idaeus L., Salix L. are important wild native melliferous plants, Helianthus annuus L., Sinapis alba L. are agricultural melliferous plants, and Filipendula ulmaria (L.) Maxim. is important polleniferous plant. Further south, in zones 4–8 (south and southeast Kazakhstan, Kyrgyzstan, Tajikistan and Uzbekistan), the principal wild native melliferous plants are Salvia L., Thymus L., Alhagi Tourn. ex Adans., Halimodendron halodendron (Pall.) C.K. Schneid., Tamarix L., Psoralea drupacea Bunge, agricultural melliferous plants – Gossypium hirsutum L. and Onobrychis Mill., weeds – Echium vulgare L., Onopordum acanthium L., Sophora L., and polleniferous plants – Hypericum L., Artemisia L., Plantago L. and Chenopodiaceae.
Resources of Rhaponticum uniflorum (Asteraceae) in Transbaikala
Authors: Shishmarev V. M. , Shishmareva T. M.
Published: April 2024

Abstract—This study examins coenopopulations of a perennial herbaceous plant Rhaponticum uniflorum (L.) DC. (Asteraceae) from different plant communities of Transbaikalia in the Republic of Buryatia and the Trans-Baikal Territory. Coenopopulations of R. uniflorum were studied in Gramineous-Filifolium, Gramineous-Artemisia-herb, Gramineous-Artemisia, Artemisia-Stipa, Filifolium-Artemisia-Gramineous, Gramineous-herb, Gramineous-Galium and other associations. Such grasses and sedges as Stipa krylovii Roshev., Leymus chinensis (Trin.) Tzvelev, Poa botryoides (Trin. ex Griseb.) Roshev., Agropyron cristatum (L.) Beauv., Achnatherum sibiricum (L.) Keng ex Tzvelev, Carex pediformis C.A. Mey. are found in associations with R. uniflorum. The maximum yield of the aerial part of R. uniflorum is 30.7 ± 3.5 g/m2 (air-dry weight) in Phlojodicarpus-Filifolium association, the minimum is 0.9 ± 0.1 g/m2 (air-dry weight) in Gramineous-Artemisia-herb association. It has been established that the occurrence of the species varies from 15 to 67% and averages 33%. We assessed the resource potential of R. uniflorum raw materials in Transbaikalia: the biological volume (17 563 kg, air-dry weight), exploitation volume (11 221 kg, air-dry weight), and the annual potential harvest (2242 kg, air-dry weight) were estimated.
Pollen Morphology of Some Melliferous Rosaceae Species of the Leningrad Region
Authors: Skomakha A. D. , Grigorjeva V. V. , Меdvedeva N. A. , Britski D. A.
Published: April 2024

Abstract—Using light and scanning electron microscopes, the pollen morphology of 11 wild and introduced melliferous species widely distributed in the Leningrad Region and belonging to 9 genera of the Rosaceae family was studied. It was found that pollen grains of all the studied species are of medium size, 25–40 microns, occasionally slightly smaller, most of them are 3-furrowed, in Sanguisorba officinalis L. 6-furrowed, with a striate or derived from it sculpture. In the dispersed state, pollen is easily determined to the family, and often to the genus. However, species of Rosa and Rubus are poorly distinguished by pollen. The data obtained can help honey producers to simplify the botanical identification of Rosaceae pollen in tested honey samples.
Solubility and Extraction of Metal Ions in Inorganic Acid–Potassium Bis(alkylpolyoxyethylene)phosphate–Water Systems
Authors: Denisova S. A. , Svezhov D. A. , Elokhov A. M.
Published: April 2024

The boundaries of the segregation region in sulfuric (nitric, chloric, hydrochloric) acid–potassium bis(alkylpolyoxyethylene) phosphate–water systems at 25°С have been determined by isothermal titration. The salting-out ability of the inorganic acid was found to increase with a decrease in the absolute value of the Gibbs energy of anion hydration. Based on the obtained diagrams, the optimum parameters of extraction were determined, and tendencies in the distribution of some metal ions in the sulfuric acid–potassium bis(alkylpolyoxyethylene) phosphate–water system were studied. Conditions for quantitative extraction of thallium(III) in the presence of alkali metal halides were found.
Radar-Shielding and Microwave-Absorbing Properties of Composite Materials Based on Shungite
Authors: Samukhina Yu. V. , Nikoladze G. M. , Kulkova T. A. , Buryak A. K.
Published: April 2024

Shungite is considered as a filler of composite materials. It is a natural composite of carbon nanoparticles with a variety of micro- and nano-sized mineral impurities that give it high conductivity and electromagnetic radar-shielding properties. The radar-absorbing and shielding characteristics of a composite material based on fine shungite and urea–formaldehyde resin are studied in the 500 MHz to 4 GHz range of frequencies. The effect the thickness of a sample has on the electromagnetic properties of the studied composite is determined.
Low-Temperature Phase Equilibria in an Ethylene Glycol–Acetone System
Authors: Solonina I. A. , Makaev S. V. , Rodnikova M. N. , Kiselev M. R. , Khoroshilov A. V.
Published: April 2024

An ethylene glycol (EG)–acetone (AC) system is studied via differential scanning calorimetry in the −140 to +40°С range of temperatures. A phase diagram is plotted over the range of concentrations. It is found that the mixtures in the system are supercooled by more than 30°C. Low-temperature melting is recorded in the region around −98°C, which corresponds to the eutectic point temperature. The devitrification of rapidly cooled samples is observed in the range of concentrations up to ~21 mol % AC, and the temperature of devitrification is determined (Tg ~ −120°C). The plotted phase diagram of the EG–AC system is compared to a water–acetone phase diagram.
Molecular Dynamic Modeling of Magnesium in the Scheme of the Embedded Atom Model
Authors: Belashchenko D. K.
Published: April 2024

Potentials of the embedded atom model (EAM) for solid and liquid magnesium are proposed. Properties of magnesium are studied by means of molecular dynamics (MD) at binodals of up to 1500 K, and under conditions of static and shock compression. The main characteristics of bcc and liquid magnesium (structure, density, energy, compressibility, speed of sound, and coefficients of self-diffusion) are calculated. The static compression isotherm at 298 K up to a pressure of 108 GPa and the Hugoniot adiabat up to a pressure of 80 GPa are calculated with allowance for electron contributions. Values of the excess energy of the surfaces of magnesium nanoclusters with 13 to 2869 particles are found, and the Gibbs–Helmholtz equation for the relationship between surface tension and surface energy is estimated.
Role of the Convective Factor in the Corrosion of Low-Carbon Steel in Solutions of Sulfuric Acid Containing Iron(III) Sulfate
Authors: Avdeev Ya. G. , Panova A. V, , Andreeva T. E.
Published: April 2024

The authors study the corrosion of low-carbon steel in solutions of H2SO4 containing Fe2(SO4)3 with and without additives of individual and mixed corrosion inhibitors. It is established that the oxidizing capacity of the given system (in which the reactions between iron, an acid solution, and Fe(III) salts are thermodynamically allowed), characterized by the redox potential of an Fe(III)/Fe(II) pair, is largely determined by its anionic composition: sulfate anions of a corrosive medium bind Fe(III) cations into complex compounds, reducing their oxidizing ability. Partial reactions of the anodic ionization of iron and the cathodic reduction of H+ and Fe(III) cations are revealed in analyzing the effect convection of the medium has on the electrode reactions of low-carbon steel. The first two reactions are characterized by kinetic control; the third, by diffusion. It is shown that the accelerating effect Fe2(SO4)3 has on the corrosion of steel in a solution with H2SO4 is mainly due to the reduction of Fe(III). In contrast, the accelerating action of Fe(III) cations affects all partial reactions of steel in an inhibited acid. There is a large drop in the apparent coefficient of diffusion of Fe(III) cations (DFe(III)) in inhibited solutions, relative to an uninhibited medium. Data on the corrosion of low-carbon steel in the given media, obtained from the mass loss of metal samples, are in full agreement with results from studying partial electrode reactions. Consideration is given to the accelerating effect Fe2(SO4)3 has on the corrosion of steel in solutions of H2SO4 with and without inhibitors. In these environments, the corrosion of steel is determined by the convective factor, which is typical of processes with diffusion control. The empirical dependence of the rate of steel corrosion on the intensity of the medium’s flow is described by linear dependence k = kst + λw1/2, where kst is the rate of the corrosion of steel in a static environment, w is the rotational speed of the propeller agitator creating the flow of the medium, and λ is an empirical coefficient.