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Changes in the hydrothermal regime of soils caused by the melting of the permafrost layer are the most important ecological factor in the dynamics of vegetation in the cryolithozone. The impact of soil thawing on the growth index (GI) of larch (Larix spp.) and on the gross and net primary productivity (GPP and NPP) of vegetation in the Arctic region of Central Siberia (sparse forests, tundra, and forest tundra) is investigated. The following hypotheses are tested: (1) gravimetric data allow us to assess the dynamics of water mass in soils; (2) thawing of frozen soils stimulates the growth of woody plants and the productivity of vegetation. This work uses methods of dendrochronology, field data, satellite gravimetry (GRACE survey), and remote sensing of GPP (Terra/MODIS survey). An analysis of gravimetric data has revealed a significant long-term trend of decreasing water mass in soils of the cryolithozone (R2 = 0.68). The amount of water released during melting is estimated at 6.4 ± 2.3 kg/m–2 per year. A close relationship was established between the GI of larch and GPP with moisture anomalies in soils (r = –0.7 and r = –0.9, respectively). The increasing temperature of the root zone and the deficit of water vapor moisture also have a positive effect on the GI of larch and the GPP value of vegetation as a whole (r = 0.6 and r = 0.6–0.9, respectively). It is established that pyrogenic carbon losses are significantly (two orders of magnitude) lower than the NPP value. Under conditions of waterlogged soils, which are typical for the Arctic, climate warming is accompanied by an improvement in the hydrothermal growth regime of the plant cover and contributes to an increase in the productivity of vegetation and the preservation of the cryolithozone status of a carbon sink area. [ABSTRACT FROM AUTHOR]

The quest for lowering energy consumption during thin film growth by magnetron sputtering techniques becomes of particular importance in view of sustainable development goals. As large fraction of the process energy is consumed in substrate heating for the purpose of providing high adatom mobility necessary to grow dense films, the most straightforward strategy toward more environment-friendly processing is to find alternatives to thermally activated surface diffusion. One possibility is offered by high mass metal ion irradiation of the growing film surface, which has been recently shown to be very effective in densification of transition metal nitride layers grown with no external heating, such that Zone 2 microstructures of the structure-zone model are obtained in the substrate temperature Ts range otherwise typical for Zone 1 growth. The large mass difference between the incident ion and the atoms constituting the film results in effective creation of low energy recoils, which leads to film densification at low Ts. Due to their high mass, metal ions become incorporated at lattice sites beyond the near-surface region of intense recoil generation leading to further densification, while preventing the buildup of residual stress. The practical implementation of this technique discussed in this Perspective employs heavy metal targets operating in the high-power impulse magnetron sputtering (HiPIMS) mode to provide periodic metal-ion fluxes that are accelerated in the electric field of the substrate to irradiate layers deposited from direct current magnetron sputtering (DCMS) sources. A key feature of this hybrid HiPIMS/DCMS configuration is the substrate bias that is synchronized with heavy metal ion fluxes for selective control of their energy and momentum. As a consequence, the major fraction of process energy is used at sputtering sources and for film densification, rather than for heating of the entire vacuum vessel. Model material systems include TiN and metastable NaCl-structure Ti1−yAlyN films, which are well-known for challenges in stoichiometry and phase stability control, respectively, and are of high relevance for industrial applications. This Perspective provides a comprehensive overview of the novel film growth method. After presenting basic concepts, time-resolved measurements of ion fluxes at the substrate plane, essential for selective control of metal ion energy and momentum, are discussed. The role of metal ion mass, energy, momentum, and concentration is described in more detail. As some applications require substrate rotation for conformal coating, a section is devoted to the related complexity in the implementation of metal-ion-synchronized growth under industrial conditions. [ABSTRACT FROM AUTHOR]

Climate changes have led to an increase in fire rates throughout the entire range of larch (Larix sibirica, L. gmelinii, and L. cajanderi). We have tested the hypothesis that natural fires are an important factor that contributes to the functional stability and dominance of larch forests in the continuous permafrost zone. We include satellite imageries, on-ground survey data, dendrochronological measurements, and ecoclimatic variables in our analysis. We find that warming in the 21st century has led to an increase in the intensity and frequency of fires and moderate and extreme (>10 000 ha) burned areas. The maximal burn areas and fire frequency are observed in the northern and southern parts of the permafrost zone, respectively. The frequency of fires and burned areas are inversely exponentially dependent on precipitation, soil and ground cover moisture, and atmospheric drought, and they increase exponentially with an increase in air temperature. In the zone of continuous permafrost, larch successfully regenerates in burned areas (up to 500 000+/ha of seedlings). In the zone of island permafrost (the southern part of the study area), the number of regeneration is 2–3 orders lower, and regeneration is represented mainly by hardwood species. The increasing fire frequency in the south of the larch range contributes to the partial transformation of the forested areas into grass and shrub communities. There is a high probability that larch will retreat from its southern range during the process of continuous permafrost thawing. Gross primary productivity (GPP) in burned areas quickly (3–15 years) recovers to the prefire level. In combination with increasing GPP trends, that indicates that larch forests retain their function as a carbon sink despite the increasing fire rate. Under conditions of an increase in fire rate, the firefighting strategy must be changed. It is necessary to realize (1) the impossibility of the total suppression of fires and (2) the ecological significance of fires in the larch forests in the cryolithozone, in which fires are the most important factor supporting the health and dominance of larch forests. Alongside that, periodic natural fires reduce the likelihood of catastrophic fires. It is necessary to focus firefighting efforts on the areas of the most important social, natural, and economic importance, while controlling burning outside these areas by monitoring methods. [ABSTRACT FROM AUTHOR]

Intense methane emission from permafrost soil into the atmosphere has long been observed in Arctic shelf and coastal zones. Due to the potential danger of this phenomenon for the environment and infrastructure, there is a need for periodic monitoring of gas pockets, including by means of land seismic exploration. In the present paper, this process is studied using numerical simulation methods. In order to reflect the main specific features of the region, a model of layered permafrost sandy soil with curved boundaries between the layers is constructed. Vertical and horizontal gas migration is represented by an increase in the number of methane reservoirs. The hyperbolic equations of linear elasticity are used as a governing system. The problem is solved by applying the grid-characteristic method in the two-dimensional case. The elastic parameters of the layers are specified in each grid cell. Wave structures exhibited by the resulting synthetic wave patterns and seismograms are analyzed in detail, allowing the direction of gas migration to be determined. The results can be used to interpret similar in situ measurements. [ABSTRACT FROM AUTHOR]

An explicit-implicit scheme is constructed for the numerical solution of the system of equations governing an elastoviscoplastic continuous medium with softening. An explicit approximation is used for the equations of motion, and an implicit approximation, for the constitutive relations, which contain a small relaxation time parameter in the denominator of the nonlinear free terms. Accurate formulas for correcting the stress deviators after the elastic computation step are derived in the case of a linear viscosity function and a nonlinear softening law. The resulting solutions of the implicit approximation for the stress deviators of the elastoviscoplastic system admit passage to the limit as the relaxation time tends to zero. The correcting formulas obtained via this passage to the limit can be treated as regularizers of numerical solutions to ill-posed elastoplastic systems with softening. [ABSTRACT FROM AUTHOR]

A new approach has been proposed to study the dynamics of crystal structure deformations under external influences using the X-ray rocking curve imaging technique. Using this approach, the spatial distribution, type, and magnitude of deformations of the crystal structure of a langasite crystal, which is promising for industrial application, exposed to the ultrasonic irradiation (excitation of a standing ultrasonic wave) have been studied. [ABSTRACT FROM AUTHOR]

Arterial hypertension leads to modification of the cerebral circulation. This results from the changes in the properties of the large arteries, the correlation between large and small arteries, and the local and systemic molecular factors. The current literature indicates several mechanical components that can modify arterial pressure and flow in the brain: 1. Functionally significant arterial stenosis (with reference to the completed or not-completed Willis circle pattern); 2. Elastic properties of the arteries that are transmitted to the microcirculation (vascular wall characteristics and central aortic pressure); including vascular modification by the general atherosclerotic burden; 3. Small vessel dysfunction; 4. Systemic and local biochemical factors that can influence cerebral microcirculation. The microvascular endothelium is the end of the arterial tree - the ultimate target organ, which responds to mechanical and biochemical, systemic, and local molecular stimuli in almost one and the same way. It is modified by systemic vascular and local metabolic requirements. When microvascular endothelium is impaired, a uniform endothelial "response to injury" follows, abnormal neurohormonal and paracrine signaling, which leads to disruption of the blood-brain barrier and the neurovascular coupling, molecular spill out, modification of local and systemic flow, which in turn closes the vicious circle of endothelial impairment. Large arteries' properties influence microvasculature and local endothelial paracrine and mechanical function. The exact correlation between large and small vessels, morphological characteristics of the aorta and cerebral microcirculation is not fully understood. Further studies of this correlation may have potential implications for the clinical practice. In this review, we herein discuss the possible interaction between the characteristics of large arteries, the small cerebral arteries, and the vascular endothelium in terms of the significance of this process for the cerebral perfusion. [ABSTRACT FROM AUTHOR]

The paper examines the dynamic behavior of elastoviscoplastic media under the action of an external load. For the case of a linear viscosity function and a nonlinear softening function, an explicit–implicit calculation scheme is constructed that permits one to obtain a numerical solution of the original semilinear hyperbolic problem. This approach does not involve the use of the method of splitting into physical processes. Despite this, an explicit computational algorithm is obtained that can be effectively implemented on modern computing systems. [ABSTRACT FROM AUTHOR]

A grid-characteristic numerical method based on tetrahedron grids is applied to simulate wave processes in a composite material under the action of a pulsed shock load. An approach is proposed to increase the approximation order of the method on an unstructured grid in the three-dimensional case. Computational results for load pulse propagation in a three-layer composite are presented. [ABSTRACT FROM AUTHOR]

Adoption of the farming systems that aim to sequester carbon in agricultural soils is one of the ways to mitigate global climate change. This study focuses on the estimation of organic carbon sequestration potential of the Russian croplands in the upper (0–30 cm) soil layer by creating a set of maps using the data from global and national databases as the input data. The maps are generated within the FAO Global Soil Organic Carbon Sequestration Potential Map (GSOCseq) project according to the unified methodology using the RothC model to predict the rate of carbon sequestration in 2020–2040 under a business as usual scenario (BAU), as well as under sustainable soil management scenarios with additional different C input (+5, +10, and +20%) resulting from the use of sustainable soil management (SSM) scenarios. The total potential sequestration rate by the croplands of the Russian Federation in the 0–30-cm layer under a BAU scenario is assessed at 8.5 Mt/year and the estimate under SSM scenarios, up to 25.5 Mt/year. The carbon sequestration by the cropland of each soil ecological zone (except for the light chestnut (Eutric Cambisols (Protocalcic)) and brown semidesert (Luvic Calcisols) soils, where it is around zero) and on a national scale is positive. The Altai krai, Omsk oblast, Novosibirsk oblast, and Krasnoyarsk krai have the greatest potential for sequestration. Several subjects of the Russian Federation—Krasnodar krai, Republic of Crimea, Rostov oblast, Primorskii krai, Republic of Adygea, and Kaliningrad oblast—demand the adoption of sustainable management of soil resources. [ABSTRACT FROM AUTHOR]

This paper presents a novel numerical method for the Newton seismic full-waveform inversion (FWI). The method is based on the full-space approach, where the state, adjoint state, and control variables are optimized simultaneously. Each Newton step is formulated as a PDE-constrained optimization problem, which is cast in the form of the Karush–Kuhn–Tucker (KKT) system of linear algebraic equitations. The KKT system is solved inexactly with a preconditioned Krylov solver. We introduced two preconditioners: the one based on the block-triangular factorization and its variant with an inexact block solver. The method was benchmarked against the standard truncated Newton FWI scheme on a part of the Marmousi velocity model. The algorithm demonstrated a considerable runtime reduction compared to the standard FWI. Moreover, the presented approach has a great potential for further acceleration. The central result of this paper is that it establishes the feasibility of Newton-type optimization of the KKT system in application to the seismic FWI. [ABSTRACT FROM AUTHOR]

Regular measurements of radio emission produced by relativistic air shower particles were started at the Yakutsk array in 1986. After monitoring of the background noise in the array area, the frequency of 30–35 MHz was chosen, because noise level is minimal in this frequency range. During this time, air showers with highest energies of 100 EeV were registered. By means of hybrid measurements of charged particles, Cherenkov light and radio emission, it was shown that signal amplitude proportional to air shower energy and shape of lateral distribution at sea level correlates with the depth of maximum development. By these characteristics, the atomic weight of primary particles that generated air shower is estimated within QGSjetII-04 framework simulation. [ABSTRACT FROM AUTHOR]

Scab formation in hot rolling is investigated. A prototype apparatus for scab removal by metal brushes is developed; the corresponding operating conditions are determined. A system is manufactured for the removal of small scabs from rolled strip in a continuous etching line. Conditions are selected for brushing the strip after etching. The optimal strip velocity and speed of brush rotation are determined. [ABSTRACT FROM AUTHOR]

We performed complex analysis of the association of polymorphic variants rs7903146 of the TCF7L2 gene and rs1801282 of the PPARG gene with metabolic parameters, insulin resistance, and β-cell function in a group of patients with early signs of carbohydrate metabolism disturbances in a sample of Tyumen citizens. The study group consisted of 64 people (39 women, 25 men) aged 40-70 years. The distribution of frequencies of alleles and genotypes of the polymorphic markers rs7903146 and rs1801282 was analyzed and associations of carriage of major homozygous polymorphisms with various phenotypic traits were identified. Genotyping for polymorphic variants of TCF7L2 and PPARG genes was performed using allele-specific PCR with primers provided by Synthol company. Carriers of homozygotes for allele C of the polymorphic marker rs7903146 significantly differed from other respondents by a higher level of C-peptide, as well as by the presence of associations with waist circumference, elevated level of glycated hemoglobin, and arterial hypertension. Carriers of homozygotes for the allele C of the rs1801282 polymorphism of the PPARG gene differed from the group of carriers of homozygotes for the allele G and the group of heterozygote carriers by higher levels of triglycerides, as well as the presence of associations with waist circumference and the level of glycated hemoglobin. [ABSTRACT FROM AUTHOR]

The development of equipment capable of operating in the Arctic environment could benefit from a mathematical model of interaction with ice. In an attempt to create such a model, a numerical simulation of a collision between a rigid body and an ice field was conducted. Discontinuous Galerkin method was used to solve the equations modeling an elastoplastic body, specifically the Prandtl–Reuss model with the Mises–Schleichert yield condition. The nature of destruction and stress distribution in ice mass were analyzed, and then the momentum change from the collision was used to estimate ice resistance. The results of this analysis show the applicability of the chosen method to the problem of ice destruction. [ABSTRACT FROM AUTHOR]

The morphofunctional features of the ovaries were evaluated in rats with functional ovarian cysts model treated with gonadotropin-releasing hormone antagonist. Administration of the antagonist significantly (p=0.009) reduced the number of cysts and the growth of follicles in the ovaries. The obtained results attest to a possibility of successful treatment of functional ovarian cysts with gonadotropin-releasing hormone antagonist. [ABSTRACT FROM AUTHOR]

We studied the expression of insulin-like growth factor 1 (IGF-1), androgen receptor (AR) and luteinizing hormone receptor (LHR) in the ovaries under the conditions of the modeling and subsequent treatment of functional ovarian cysts with gonadotropin-releasing hormone antagonist (ant-GnRH). The intensity of IGF-1, LHR, and AR expression in the generative elements of rat ovaries changed under conditions of functional ovarian cysts simulation, as well as during treatment with ant-GnRH. In both experimental groups, the expression levels of the studied markers in preantral follicles and epithelial lining of cysts were found to be related to the number of growing follicles and cysts. A divergence of LHR and AR expression indices and a more pronounced decrease in the number of cystic cavities were observed in the group receiving ant-GnRH. These changes demonstrate a positive effect of ant-GnRH on intra-ovarian regulatory factors and a therapeutic effect in functional ovarian cysts. [ABSTRACT FROM AUTHOR]

This research paper presents an investigation into the modeling of ultrasonic wave propagation within composite materials, employing advanced grid-characteristic methods and Chimera grids. The study utilizes an isotropic linear elastic medium as a fundamental model to describe the dynamics of individual structures in composite materials. To solve the problems, the grid-characteristic method was used on both structured rectangular and curvilinear grids. The methodology introduces Chimera grids within a single uniform background mesh, allowing for independent solutions in each grid at subsequent time steps. This approach not only enhances the precision of describing wave front behavior at material contact boundaries but also streamlines computational processes through parallelization, showcasing exceptional scalability. The results demonstrate significant advancements in understanding ultrasonic wave dynamics within composite materials, with implications for refining simulation techniques in the future. [ABSTRACT FROM AUTHOR]

Rich with fossil minerals, offshore areas of the Arctic region attract a lot of attention from researchers, which creates the necessity to investigate the structure of the subsurface space. This work is dedicated to the simulation of one of the standard methods used, which is seismic survey. The computational domain was constructed by taking into account the main features of the offshore areas: heterogeneous ice field, water, and layered ground with an oil reservoir. The linear elasticity model was chosen as the governing system of equations and solved using the grid-characteristic method on rectangle grids. Ice was simulated using the Maxwell viscoelastic model and the Kukudzhanov elastoviscoplastic model, taking into account the temperature dependence of its Young's modulus. The results reconstruct different wave phenomena, such as Rayleigh waves, Scholte waves, reflected from the reservoir wave front, and seismic ghost reflections, which can be used for the analysis of the structure of geological layered media. [ABSTRACT FROM AUTHOR]

In the recent years the Arctic onshore and offshore areas has become the region of interest. In the cold conditions, inhomogeneous permafrost ground with ice and methane inclusions is formed. It affects all conducted full-scale seismic measurements. The aim of this work is creation of the computational settings for reproduction of such wave processes that is able to encompass the main features of the region. Two approaches to numerical modeling are introduced and compared on the obtained wave patterns and seismograms. The first one suggests the construction of multiple curvilinear grids. For the second one, a single rectangle grid is created with different elastic parameters in each cell. Linear elasticity model is used as a governing system of equations. It was solved using the grid-characteristic method on structured grids. As a result of the analysis, the advantages and disadvantages of the approaches are distinguished. The influence of the domains on the wave profiles is studied, reproduced rich wave phenomena is defined. [ABSTRACT FROM AUTHOR]

In this manuscript we discuss a new modification of the grid-characteristic method for calculating the seismic stability of buildings in the Far North, taking into account the presence of soil piles and soil subsidence between them with a topography of an arbitrary shape. We introduce a new method of covering the integration domain with various types of computational grids. This hybrid approach of the use of computational grids to solve this class of problems is discussed in detail in the manuscript. Attention is paid to the issue of the grids generation, the conformity of contacts between them and the possibility of using interpolation, including the introduction of hierarchical coordinate step refinement. The types of grids under consideration are either Cartesian (with a constant step in Cartesian coordinates), or structured curvilinear (body-fitted and boundary-conforming) to take into account soil subsidence of arbitrary shape. A number of test calculations have been performed. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of constructing a numerical solution to the system of equations of an acoustic medium in a fixed domain with a boundary. Physically, it corresponds to seismic wave propagation in geological media during seismic exploration of hydrocarbon deposits. The system of first-order partial differential equations under consideration is hyperbolic. Its numerical solution is constructed by applying a grid-characteristic method on an extended spatial stencil. This approach yields a higher order approximation scheme at internal points of the computational domain, but requires a careful construction of the numerical solution near the boundaries. In this paper, an approach that preserves the increased approximation order up to the boundary is proposed. Verification numerical simulations were carried out. [ABSTRACT FROM AUTHOR]

Abstract—The dependence of the Russian industry on the import of rare metals is considered. The volume of imports and their geographical structure, including those from the so-called "unfriendly countries," are presented. The rare metals the prospects for replacing them with imports in the near future seem to be low are considered. [ABSTRACT FROM AUTHOR]

The article considers showers produced by primary particles with energies eV. The showers were registered in the course of continuous long-term observations at the Yakutsk array of extensive air showers. In the present work, the mathematical processing of showers was repeated and the phenomenology of the charged component, muons with threshold GeV in the region of highest energies was refined. Mass composition of primary particles producing air showers with energy greater than eV was made based on the muon component. [ABSTRACT FROM AUTHOR]

This article presents the results of a comparative analysis of the radial increment of various larch species and provenances growing on a common ecological background in experimental forestry established in 1965–1967 on the Krasnoyarsk forest steppe by employees of the Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences. The provenances of Siberian larch (Larix sibirica Ledeb.) from different elevation belts of the Southern Siberian Mountains, Gmelin larch (L. gmelinii Rupr.) from the Trans-Baikal and Zeya provinces (Eastern Siberia), and Japanese larch (L. leptolepis Gord) introduced from the island of Sakhalin are studied. Based on the cluster analysis of radial increment series, four groups of provenances are identified with different growth strategies, depending on the response to environmental factors: mountain–forest steppe and mountain–taiga provenances of Siberian larch and provenances of Gmelin larch from Transbaikalia. The provenance of Japanese larch from Sakhalin has formed a separate cluster. The highest values of radial increment are found in groups of mountain–forest-steppe provenances formed by Siberian larch and Gmelin larch trees introduced from East Siberian provinces. Low values of radial increment are noted in provenances of Siberian larch trees from Southern Siberia mountain–taiga zone and Japanese larch from Sakhalin. Dendroclimatic analysis is used to identify the relationship between the environmental variables of the introduction zone and the radial increment of the studied provenances. In the Krasnoyarsk forest steppe, the main factor limiting radial increment is the moisture content of the root layer in the middle of the growing season (July–August). Larch trees introduced from wetter habitats respond more strongly to an increase in water stress, while the radial increment of trees taken from drier habitats responds positively to an increase in the length of the growing season. [ABSTRACT FROM AUTHOR]

The theories and mechanisms that explain the processes of modification of primary silicon in hypereutectic silumins are considered. The solidification of a hypereutectic silumin containing a rare earth element (REE), namely, yttrium, ytterbium, samarium, erbium, lanthanum, or neodymium, is studied. The phase transformation temperatures and the parameters that take into account the precipitation of a solid phase in the solidification temperature range are determined. Differences in the solidification parameters and the character of solid-phase precipitation in alloys modified by yttrium, ytterbium, samarium, erbium, cerium, or neodymium are revealed. Further investigations should be performed to clarify the mechanism of the REM modification of primary silicon in hypereutectic silumins. [ABSTRACT FROM AUTHOR]

The paper considers the problem of choosing an initial approximation for gradient optimization methods as applied to the inverse problem of restoring the velocity distribution in a heterogeneous continuous medium. The behavior of the medium is described by a system of acoustic equations, and the direct problem is solved by applying a finite-difference scheme. L-BFGS-B is used as a gradient optimization method. The gradient of the error functional with respect to the medium parameters is calculated by applying the adjoint state method. An initial approximation for the gradient method is obtained using a convolutional neural network trained to predict the velocity distribution in a medium from its wave response. It is shown that a neural network trained on responses of simple layered structures can be successfully used to solve the inverse problem for a much more complex Marmousi model. [ABSTRACT FROM AUTHOR]

A new approach is considered for increasing the order of accuracy of the grid-characteristic method in the region of coefficient jumps. The approach is based on piecewise polynomial interpolation for schemes of the second and third orders of accuracy for the case where the interface between the media is consistent with a finite-difference grid. The method is intended for numerical simulation of the propagation of dynamic wave disturbances in heterogeneous media. Systems of hyperbolic equations with variable coefficients are used to describe the considered physical processes. The description of the numerical method and the results of its testing are given. [ABSTRACT FROM AUTHOR]

The system of linear acoustic equations is hyperbolic. It describes the process of acoustic wave propagation in deformable media. An important property of the schemes used for the numerical solution is their high approximation order. This property allows one to simulate the perturbation propagation process over sufficiently large distances. Another important property is schemes' monotonicity, which prevents the appearance of non-physical oscillations in the solution. In this paper, we present linear quasi-monotone and hybrid grid-characteristic schemes for a linear transport equation and a system of one-dimensional linear acoustic equations. They are constructed by a method of analysis in the space of unknown coefficients proposed by A.S. Kholodov based on the grid-characteristic monotonicity criterion. Wide spatial stencils with five to seven computational grid nodes are considered. Reflection of a longitudinal wave with a sharp front from the interface between media with different parameters is used as a test to compare the obtained numerical solutions. [ABSTRACT FROM AUTHOR]

The modern production and consumption of oil refining catalysts in Russia are characterized. A high level of import of oil refining catalysts is shown. Commodity chains of certain types of metallic raw materials used for the production of catalysts of different types are analyzed. Measures to weaken import dependence on the supply of metals and their compounds by Russia are proposed. [ABSTRACT FROM AUTHOR]

Abstract—A mathematical model has been developed to calculate the force of uniaxial tension of a fiber-reinforced composite material (FCM) with an anisotropic matrix when fibers are destroyed. The proposed model takes into account the crystallographic texture of the matrix material and the direction of fiber laying, which allows us to formulate requirements for the texture improving the strength of FCM. The performed analysis has demonstrated that the crystallographic orientations of deformation type provide higher strength properties of FCM in comparison with those of recrystallization type. The highest increase in the strength is observed upon reinforcement by fibers at an angle of about 45° to the rolling direction if the structure of the sheet is comprised of orientations of deformation type. For the orientations of recrystallization type, reinforcement should be performed in the rolling direction ({100}〈001〉, {110}〈001〉); for the orientation {100}〈001〉, it should be additionally performed in the transverse direction. [ABSTRACT FROM AUTHOR]

Climate change increases the frequency of forest fires throughout the entire boreal zone. This paper examines the long-term wildfire dynamics in pine forests of Central Siberia, relationships between environmental and climatic variables on the one hand and the occurrence frequency of fires and size of burnt forest areas on the other, and the postfire dynamics of vegetation cover productivity. A coupled analysis of ground survey data, remote sensing data (spectroradiometric and gravimetric information collected by the Terra/MODIS and GRACE satellites), and dendroecological data is performed. In the period from the 18th to the 20th century, fire return intervals decreased from 33 to 20–25 years. No statistically significant trends in fire occurrence frequency were identified in the current century; however, catastrophic (i.e., affecting more than 1 million ha) fires were observed in its second decade, and both the number of fires and size of burnt areas have significantly increased (by 3.5 and 3.0 times, respectively). The frequency of fires and size of burnt areas closely correlate with wetting and temperature conditions in the prefire period. Furthermore, fire statistics parameters correlate with wetting conditions (precipitation amount, moisture content in the ground cover and soil, and the Self-Calibrated Palmer Drought Severity Index (sc-PDSI)) stronger than with air temperature. It is shown that equivalent water thickness values obtained using gravimetric methods can be used in fire risk assessments. High correlation levels were identified between the growth index of pine trees and vegetation cover productivity indices (i.e., gross primary productivity (GPP) and net primary productivity (NPP)) generated based on remote sensing data. The results indicate that these indices can be used to estimate forest stand productivity dynamics. The vegetation cover productivity and the radial growth index of pine trees in burnt areas quickly (within a decade) restore to prefire values, which indicates that northern pine forests retain their carbon sequestration function despite climate change and the increasing frequency of fires. [ABSTRACT FROM AUTHOR]

The grid-characteristic method on structured grids is applied to various problems related to railway-traffic safety, as well as to obtain results of full wave modeling using this method and analyzing them for a better understanding of the physical processes occurring under conditions of heavy and high-speed traffic on various sections of the track. The problem involves the consideration of traffic on a ballasted and ballastless bridge desk. In the course of computer simulation, various wave fields and dynamic distributions of pressure and components of the Cauchy stress tensor are obtained during the traffic. The calculation time during which the propagation of wave processes occurs in various bridge structures is estimated. The results obtained give an idea of wave phenomena during the traffic in the area of bridges and along the railway track as a whole. [ABSTRACT FROM AUTHOR]

In the paper inverse problems of exploration seismology were solved with use of convolutional neural networks to determine the spatial position and physical characteristics of geological fractures, such as the proportion of glued surface and the type of saturation. The training and validation sets were formed with use of numerical modeling by the grid-characteristic method on unstructured meshes in the two-dimensional case. The constitutive equations of continuum mechanics were used in paper, the fractures in the integration domain were simulated discretely—this approach made it possible to obtain the most detailed patterns of wave responses. [ABSTRACT FROM AUTHOR]

Nowadays, the grid-characteristic method is gaining popularity for linear hyperbolic systems of equations. This method is commonly used for the simulation of the wave propagation process in deformable media. This problem requires specific properties of the used numerical method: a high approximation order and a monotonicity. One of the robust monotonicity criteria is the grid-characteristic one, proposed by A. S. Kholodov. This work is devoted to the adaptation of this approach for broaden spatial stencils. On the seven-point stencil the fifth order linear scheme and quasi-monotonic schemes were constructed. Their behavior was evaluated on the linear transport equation with the constant coefficient. Based on the problem with the initial condition of a complex form, the obtained numerical solution was compared with the other ones. The achieved approximation order was calculated based on the numerical experiment results. The detailed analysis was used to choose the scheme with the best behavior. [ABSTRACT FROM AUTHOR]

Diagnostic ultrasound is a common practice in medicine, being a cheap and reliable source of information in a wide range of medical situations. The technology is designed and calibrated for a specific structure of media under investigation, which corresponds to soft tissues of a human body. In the presence of homogeneous areas—hard inclusions of various shapes (e.g., bones, implants), gas or fluid bubbles—certain types of artifacts can be observed. This research uses the grid-characteristic numerical method to model elastic waves in heterogeneous media and offers an interpretation of some types of artifacts that can be observed on a B-scan. [ABSTRACT FROM AUTHOR]

The possibilities of a new class of adaptive X-ray optical elements based on bending piezoelectric actuators for practical implementation of time-resolved experiments using X rays and synchrotron radiation—fast high-resolution X-ray diffractometry and fast X-ray absorption spectroscopy—are described. Examples of studies and results obtained using the proposed elements and the corresponding techniques are presented. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of seismic wave propagation in gradient geological media. Their dynamic behavior is described using the acoustic approximation and the numerical integration of the initial-boundary value problem for the acoustic wave equation with spatially variable mechanical parameters. A grid-characteristic numerical method is developed that explicitly takes into account the gradient of the medium. The numerical solutions are compared with results obtained using a piecewise constant model of the medium in the one-dimensional case. [ABSTRACT FROM AUTHOR]

The aim of this work is to develop a hybrid computational method that combines the grid-characteristic method on regular structured grids with the discontinuous Galerkin method on unstructured tetrahedral grids. The proposed method makes it possible to describe integration domains with complex-shaped boundaries and contact boundaries and to calculate seismic fields taking into account the topography of the Earth's surface, while saving computational resources. This modification of the method in the three-dimensional case has been proposed in this paper for the first time. Examples of using the developed method for calculating elastic wave phenomena arising during seismic prospecting are given. By way of testing, a comparison is made with results produced by the grid-characteristic method on curvilinear structured grids. The proposed hybrid method can be used not only for seismic prospecting, but also for calculating wave phenomena in other objects of complex shape. [ABSTRACT FROM AUTHOR]

The article is a continuation of the previous authors' works in the framework of the wet drawing study. The process of wet superthin and extra-thinest drawing of brass-plated steel wire is considered in order to increase the wear resistance of dies. The analysis of various types of drawing tools (hard-alloy dies, synthetic diamond dies, natural diamond dies) was carried out for the relevance of its application for drawing wire of small diameters. Classification of the components of operational durability of the drawing tool is given. A description of the research methodology is given, including the procedure and conditions for conducting measurements, the industrial equipment used to obtain the initial data, as well as the type of drawbench (drawing machine). The paper presents a comparative analysis of the data obtained with the results of studies by other authors obtained for a similar drawing tool. The main characteristics of the wear resistance distribution (asymmetry, kurtosis, coefficient of variation) are calculated. Based on the statistical analysis of an array of experimental data for a sample of more than 500 samples, a high correlation of the wear resistance of dies with the criterion of the safety coefficient and a weak correlation with the criteria of the drawing force and stress were revealed. It is shown that the optimal, i.e., the highest and most stable results on the drawing tool wear resistance are achieved with the values of the safety coefficient in the range from 1.9 to 2.5. A formula is proposed for determining the value of the safety factor depending on the wire diameter, which provides the maximum values of tool wear resistance along the drawing schedule. The results obtained are recommended for use in the design of new wet drawing schedules using synthetic diamond dies. [ABSTRACT FROM AUTHOR]

Hard Ti1-xAlxN thin films are of importance for metal-cutting applications. The hardness, thermal stability, and oxidation resistance of these coatings can be further enhanced by alloying with TaN. We use a hybrid high-power pulsed and dc magnetron co-sputtering (HIPIMS/DCMS) technique to grow dense and hard Ti0.41Al0.51Ta0.08N alloys without external heating (Ts<150 °C). Separate Ti and Al targets operating in the DCMS mode maintain a deposition rate of ~50 nm/min, while irradiation of the growing film by heavy Ta+/Ta2+ ions from the HIPIMS-powered Ta target, using dc bias synchronized to the metal-ion-rich part of each HIPIMS pulse, provides effective near-surface atomic mixing resulting in densification. The substrate is maintained at floating potential between the short bias pulses to minimize Ar+ bombardment, which typically leads to high compressive stress. Transmission and scanning electron microscopy analyses reveal dramatic differences in the microstructure of the co-sputtered HIPIMS/DCMS films (Ta-HIPIMS) compared to films with the same composition grown at floating potential with all targets in the DCMS mode (Ta-DCMS). The Ta-DCMS alloy films are only ~70% dense due to both inter- and intra-columnar porosity. In contrast, the Ta-HIPIMS layers exhibit no inter-columnar porosity and are essentially fully dense. The mechanical properties of Ta-HIPIMS films are significantly improved with hardness and elastic modulus values of 28.0 and 328 GPa compared to 15.3 and 289GPa for reference Ta-DCMS films. [ABSTRACT FROM AUTHOR]

The motion, deformation, and destruction of a thin fiber under the action of a transverse shock load are numerically simulated. The fiber is described by the equations of Rakhmatulin's theory. The system of dynamic equations is solved using the finite-difference method. The parameters for the model can be obtained directly from impact loading experiments, so the dependence of the material properties on the strain rate can be taken into account. Numerical results for aramid fibers under impact load are presented. Loading modes with and without fiber breakage are considered. A direct comparison of the numerical and experimental data is presented. A good agreement between them is demonstrated. The resulting validated numerical model of a single fiber can further be used to describe a fabric material as a system of interacting fibers. [ABSTRACT FROM AUTHOR]