bluuebunny/crossref_metadata_2025 huggingface dataset:
Brillouin-zone characterization of piezoelectric material intrinsic energy-harvesting availability
Authors: Patrick Jatin , Adhikari Sondipon , Hussein Mahmoud I.
Published: June 2021

Vibration energy harvesting is an emerging technology that enables electric power generation using piezoelectric devices. The prevailing approach for characterization of the energy-harvesting capacity in these devices is to consider a finite structure operating under forced vibration conditions. Here, we present an alternative framework whereby the intrinsic energy-harvesting characteristics are formally quantified independent of the forcing and the structure size. In doing so, we consider the notion of a piezoelectric material rather than a finite piezoelectric structure. As an example, we consider a suspended piezoelectric phononic crystal to which we apply Bloch’s theorem and formally quantify the energy-harvesting characteristics within the span of the unit cell’s Brillouin zone (BZ). In the absence of shunted piezoelectric circuits, the wavenumber-dependent dissipation of the phononic crystal is calculated and shown to increase, as expected, with the level of prescribed damping. With the inclusion of the piezoelectric elements, the wavenumber-dependent dissipation rises by an amount proportional to the energy available for harvest which upon integration over the BZ and summing over all branches yields a quantity representative of the net available energy for harvesting. We investigate both monoatomic and diatomic phononic crystals and piezoelectric elements with and without an inductor. The paper concludes with a parametric design study yielding optimal piezoelectric element properties in terms of the proposed intrinsic energy-harvesting availability measure.
Observing invisible axions with gravitational waves
Authors: Gorghetto Marco , Hardy Edward , Nicolaescu Horia
Published: June 2021

If the Peccei-Quinn symmetry associated to an axion has ever been restored after inflation, axion strings inevitably produce a contribution to the stochastic gravitational wave background. Combining effective field theory analysis with numerical simulations, we show that the resulting gravitational wave spectrum has logarithmic deviations from a scale invariant form with an amplitude that is significantly enhanced at low frequencies. As a result, a single ultralight axion-like particle with a decay constant larger than 1014  GeV and any mass between 10-18 eV and 10-28  eV leads to an observable gravitational wave spectrum and is compatible with constraints on the post-inflationary scenario from dark matter overproduction, isocurvature and dark radiation. Since the spectrum extends over a wide range of frequencies, the resulting signal could be detected by multiple experiments. We describe straightforward ways in which the Peccei-Quinn symmetry can be restored after inflation for such decay constants. We also comment on the recent possible NANOgrav signal in light of our results.
Precise evaluation of

and axion-like particle production *
Authors: Li Shi-Yuan , Li Zhen-Yang , Lu Peng-Cheng , Si Zong-Guo
Published: June 2021

We study the decay of the SM Higgs boson to a massive charm quark pair at the next-to-next-to-leading order QCD and next-to-leading order electroweak. At the second order of QCD coupling, we consider the exact calculation of flavour-singlet contributions where the Higgs boson couples to the internal top and bottom quark. Helpful information on the running mass effects related to Yukawa coupling may be obtained by analyzing this process. High precision production for

within the SM makes it possible to search for new physics that may induce relatively large interactions related to the charm quark. As an example, we evaluate the axion-like particle associate production with a charm quark pair in the Higgs decay and obtain some constraints for the corresponding parameters under some assumptions.
Application of substitute building materials in geogrid reinforced soil structures and other civil engineering constructions
Authors: Schwerdt S , Schneider P
Published: June 2021

Mineral waste has become not only the largest waste stream in many countries, but also a reliable source of material to replace primary raw materials. Much of this material is already being used successfully. However, the potential of many materials such as slag or ashes, is currently not fully unlocked as this kind of material is used only for backfilling, often referred to as downgrading. In this study, the use of recyclables in higher value applications was investigated. In several laboratory tests, the usability of substitute building materials (SBM) in green applications, such as green roofs, green facing elements or fill material in (geogrid) reinforced soil structures ((G)RSS), was tested. The study concept includes both, soil mechanical laboratory tests and greening tests on SBM. The greening tests showed that broken bricks are suitable when mixed with organic materials. Pure brick rubble material can only be insufficiently greened. Chemical and soil mechanics tests were carried out with the fill materials. Some materials such as Lignite fly ash were excluded from soil mechanical tests because of insufficient chemical properties. These materials are not suitable for building applications without a sealing layer. Many other materials, such as recycled concrete or different kinds of slags have equivalent or even better soil mechanical properties than primary materials. Many of these materials also have chemical properties that allow almost unlimited use in construction.

Based on the laboratory results, the construction of an RSS with complete substitution of the primary building materials will be started as a large-scale pilot test in the next step.
Stress-strain state in soil massif when interacting with incompressible barrette and raft
Authors: Ter-Martirosyan Z G , Dam H H
Published: June 2021

The statement and solution of problems on the interaction of incompressible barrette with the soil massif as part of a pile-raft foundation are considered, taking into account the barrette steps, diameters, the embedded length, as well as nonlinear soil behaviors by analytical and numerical methods using Plaxis-3d. It is shown that these parameters have a significant effect on the stress-strain state (SSS) of the soil massif interacting with the barrette-raft system. By taking the approach above engineers entirely manage to gain formulas so that to determine the SSS in incompressible barrette, as well as to assess the settlement of this system. For the sake of achieving the solution to problem above, the behaviors of the barrette-raft system, the soil massif are assumed to be elastic.
Jet grouting technique and strength properties of jet grout columns
Authors: Guler E , Gumus Secilen G
Published: June 2021

Jet grouting is a relatively recent development which is applied for mainly ground improvement purposes and provides effective solutions to many geotechnical and geoenvironmental problems. Jet grouting technique differs substantially from the other grouting techniques in that this technique can be used in treating a wide range of soil types. Therefore the application fields of jet grouting are rapidly increasing. The main emphasize in this paper is given to the strength properties of jet grout columns. The strength properties of jet grout columns is investigated by the example of five case studies. The subsoil conditions and foundation engineering evaluations of the investigation areas are presented in the case studies. The strength properties are investigated by referring to the unconfined compressive strength test results of the core samples obtained from jet grouting columns.
Soil areas numerical determination aimed at correction of a building tilt
Authors: Melnikov R , Pronozin Y , Stepanova M , Bartolomey L
Published: June 2021

The analysis of the soil area in the base of an absolutely stiff building has been proposed in the article. Influencing this area it is possible to correct the tilt. The authors of the paper provide an overview of various methods of the tilt correction. The study of the soil spreading in the basement soil has been carried out; the soil area is less deformed under eccentric loading than under central loading. This area is proposed to be called the area of “deficit” strains. The first series of numerical computations has shown that this area depends only on the tilt of an absolutely stiff building; it is described in accordance with a linear law when using simple geometric shapes: a sector and a segment. The second series of computations has illustrated that when decreasing deformation and strength characteristics of this area, the building tilt is corrected. In here, the entire area of the “deficit” strains is not required to be used, just its basic area incorporating a part of a sector and a segment. These areas are concentrated at the edge of the footing. The optimal range of values for a single coefficient which lowers the basic mechanical characteristics of soil has been established. Conclusions on the computations have been drawn and plan for further research has been proposed.
The 3D numerical model of the stone column in soft clay soils
Authors: Znamenskii V V , Hegazy O M , Sayed D A
Published: June 2021

An end bearing stone column is one of the most common types of stone columns, which completely penetrates through a layer of soft clay soils, resting on much stiffer soils. This article presents a numerical model (analyses) of the stone column used to strengthen the soft clay soil. The analyses were performed using a three-dimensional model in FLAC3D. To investigate the effect of the stone column on strengthening soft clay soils, a dimensionless parameter called the settlement improvement ratio (Ks) is used. The results show that, the settlement improvement ratio (Ks) increases with an increasing diameter of the stone column. The lateral deformation of the stone column decreases with the increasing stone column diameter, and the maximum lateral deformation was occurred at approximately (1.0 to 1.5) diameter from the top of the surface.
Effect of freezing and thawing on soil permeability: newly equipment and experimental results
Authors: Korshunov A A , Doroshenko S P , Nevzorov A L , Boldyrev G G
Published: June 2021

In a cold climate design of dams, clay barrier liners on landfills, and structures on frost-susceptible soils is a challenge for geotechnical engineers. During service life of the structures a frost heave may reach 15-20% of the depth of a frost penetration and an uplift movement are accompanied by the formation of layered or lattice cryogenic texture. When thawing, macro- and micropores are formed instead of ice lenses. Basically pores are oriented predominantly along frost front. They are a reason of horizontal water permeability increase, consequently, reduce of stability of the slopes and decrease of the effectiveness of the landfill clay barrier liners. The paper presents a new apparatus for studying water permeability and frost heave of soils which allows to carry out horizontal or/and vertical permeability tests (along and across layered cryogenic texture) after assigned number of freeze-thaw cycles without withdrawal of a soil sample from apparatus. The results for clay and fine sand samples are obtained. Clay and fine sand samples showed an increase of horizontal hydraulic conductivity after 2 - 4 freeze-thaw cycles. Relationship between water flow velocity and hydraulic gradient for non-Darcian and Darcian flow is obtained as a result of vertical permeability tests of clay samples in unfrozen state.
Genetically nonlinear combined model of pile field under dynamic impacts
Authors: Nuzhdin L V , Mikhailov V S
Published: June 2021

The authors propose a combined approach for definition of the shear rigidity of the multilayered soil which is cut through by a pile. The solution for the vertical direction is presented in the view of an axisymmetric problem. As to the horizontal direction, the solution is presented in view of a beam on elastic subsoil with genetically non-linear transition to equivalent horizontal rigidity of the wide pile field in condition of dynamic forces action. The axisymmetric solution provides visual clarity in the analysis of the stress-strain state of the pile and near-pile soil in comparison with the approved analytical methods. To speed up calculations at the stage of the main combination of constant and long-term impacts, the vertical rigidity of the base under the foot of the pile can be calculated analytically as for a stamp on an elastic-plastic base. The horizontal rigidity is considered as for a discrete single bent pile in the medium of an elastic layered half-space at the stage of formation of the stress-strain state of the system under the main combination of static loads. At the final stage of short-term or special load, a transition to the integral shear rigidity of a pile field is proposed.
Risks of using artificial sand base in difficult geotechnical conditions
Authors: Bragar E P , Rachkov D V , Zh Zhussupbekov A , Tarasenko A A
Published: June 2021

Excavation of pits, trenches for foundations of civil buildings and industrial structures in saturated clayey soils often leads to soil structural change and great decrease in the soil strength and deformation characteristics. In some cases, an artificial sand base is used as a method for construction on saturated clayey soils. However, technology violations and unsuitable material used during construction can be the reason for excess settlement of the erected facilities. The study includes a real example of an emergency situation at gantry crane railways with three hundred meters in length in the town of Tobolsk. The artificial base was made using local sand with specific properties such as subsidence and frost heaving, which were not taken into account in the design process. The observed excess non-uniform base deformations were up to 240 mm. The base properties of the silty sand were analyzed in a laboratory study. Two tests were carried out to simulate possible impact on the artificial sand base. They showed that the values of the initial compaction factor Kcom
of sand base were found in the range of 0.87-0.92. So, the base subsidence was about 12% of the actual base deformation and the total base settlement under the total operation loading made about 19%.
Determination of the characteristics of compacted sandy soils by field and laboratory methods
Authors: Yu Chunyuk Dmitry , Kopteva Olga V
Published: June 2021

Nowadays, it is a common practice to erect buildings and structures on base soils, which were previously compacted in various ways. During this process, the physical and mechanical properties of the following base soils are changed in order to increase their bearing capacity. In this article, on the example of some construction sites, test studies of the physical and mechanical properties of soils are described. Some results of these studies, both before and after soil compaction are given. Physical, deformation and strength characteristics were determined in both laboratory and field conditions. During the work, the following objectives were set: to conduct full-scale (field) and laboratory studies aimed at reliable determination of the strength and deformability characteristics of compacted sandy soils; to analyze the characteristics of compacted soils that determine the development of deformations over time; to conduct experimental field and laboratory studies on the use of compacted sandy soils of various granulometric composition and density as the structure base; to establish a set of controlled parameters of the compacted soils properties on the basis of conducted analytical studies. Thus, the object of the study during this work was sandy soils with different granulometric composition. The conclusions were drawn on the results of the work.
Crack resistance estimation of fibre reinforced tunnel linings constructed by conventional method in rocks
Authors: Zertsalov M G , Rusanov V E , Minin K E , Polysaeva A I
Published: June 2021

The article represents crack control research results of horseshoe-shaped fibre reinforced concrete tunnel linings which are constructed by conventional tunneling method on a full cross-section in rocks. Based on linear fracture mechanics an alternative method for estimation of the crack resistance for such kind of linings is proposed. The research was carried out by using the finite element method supported with experiment planning method.
Model and field experimental studies of reinforced clay bases
Authors: Kleveko V I
Published: June 2021

Using reinforced bases in clay soils is studied still insufficiently well. Therefore, in order to use the building practice of constructions of the bases on the reinforced ground it is necessary to carry out the analysis of their is stress-deformed condition to reveal a rational scope and to develop optimum constructions of the reinforced bases. For studying of work of the reinforced bases complex theoretical experimental researches have been carried out: laboratory modelling researches, natural tests, numerical modelling of work of the reinforced bases in water sated clay soils. The tests revealed that the single layer reinforcing clay base results in an increase in bearing capacity of 1.35 times the base. Effectiveness of reinforced bases increases with increasing precipitation structures. Stress-strain state reinforced base is markedly different from the stress-strain state of reinforced base. Introduction reinforcing element transforms the stress distribution in the core base. Stresses concentrate in an area of the reinforcing layer and decrease in the area below it. Redistribution of the active area in the vertical stress is reinforced based on depth amount 1.0-1.25 d from the base of the stamp, and in width by up to 1.0 d from the axis of the die. The test results showed high efficiency of reinforcement to increase the bearing capacity of foundations in clay soils. The carried out researches have allowed to receive a qualitative and quantitative picture of reinforced soil work of the bases and their stress-deformed condition to define a rational scope and to develop recommendations or their designing.
Bearing capacity of bored piles made with polymer drilling mud
Authors: Lesnitsky V , Shulyatev O , Shulyatev S
Published: June 2021

The main results of the work on the analysis of the possibility of using polyacrylamide drilling muds for the installation of drill piles, barrettes and slurry walls in sandy soils are presented. The results of the study of the possibility of solutions to keep the walls of boreholes from collapse, laboratory studies of the effect of polyacrylamide solutions on the shear strength of soils, as well as the results of field tests of piles with static pulling load are reflected.
Determination of concreting quality of bored piles by CHA method
Authors: Bartolomei I L , Karpushko M O , Karpushko E N
Published: June 2021

In the presented article, the authors consider the issues of quality control of bored piles in the practice of bridge construction. The importance of quality control of these pile structures is emphasized. The basic requirements for quality control in the production of construction works and their acceptance are presented. A description of the control method is given. As a practical example, the results of quality control of the execution of bored piles by the method of cross well ultrasonic scanning at the bridge over the river Chusovaya. An assessment of the state of bored piles after testing is given.
Experience of using express-methods for determining the fill soils characteristics
Authors: Sazonova S A , Ponomaryov A B
Published: June 2021

When designing the foundation slab for a building facility, engineers decided to partially replace the base soils with a sand cushion having a deformation modulus of 18-25 MPa. This paper presents the results of quality control of fill soils compaction during the cushion construction. The compaction factor and the compression modulus of deformation were determined for each layer of the sand pad. There were also three stamp tests carried out on its surface. At the same time, several of additional studies were performed to control the quality of sand cushion compaction using express methods: the determination of the dynamic modulus of soil elasticity using the dynamic density meters DPG 1.2 and Terratest 5000 BLU; the determination of the sand cushion homogeneity by the CMPW geophysical method (the correlation method of refracted waves). The test results were presented, and a conclusion was made.
Application of variable pitch reinforcement with horizontal geosynthetic elements in pads made from cohesive soils
Authors: Tatiannikov D A , Ponomaryov A B
Published: June 2021

The paper is devoted to researching into the behaviour of reinforced pads made from cohesive soil. Compacted soft-plastic loam was considered as a pad material, and woven geotextile was used as an reinforcing element. The research was aimed at testing a well-known approach to the usage of a variable reinforcement pitch in cohesive soil pads. The goal was achieved by solving test problems for various types of reinforcement in the Plaxis 2D software package. Based on the results of the research, the formula for determining the arrangement of reinforcing layers at a variable reinforcement pitch in cohesive soil pads was adjusted. It was also found that when the layers were arranged at a pitch of 200 mm or less, the reinforcing effect in cohesive soils practically did not occur. In addition, it was confirmed that at a variable pitch of reinforcement, there was the most complete “inclusion of geosynthetic materials in work” in comparison with other considered cases of reinforcement.
Field testing of municipal solid waste and estimation of waste properties
Authors: Ofrikhter V G , Ofrikhter I V , Bezgodov M A
Published: June 2021

As biodegradation proceeds, municipal solid wastes (MSW) acquire pronounced soil-like properties and upon completion of the process can be used as the foundation. The solid waste massif is an inhomogeneous soil-like mass which requires non-destructive and minimally invasive methods of research. The cone penetration testing of MSW by piezocone (CPTU) in combination with the multichannel analysis of surface waves (MASW) provide extensive data about physico-mechanical properties of wastes, which are usually unavailable in traditional approaches and which can be directly used in geotechnical stability calculations of the waste massif.
Estimation of load-set behavior of driven concrete piles using artificial neural network and cone penetration test
Authors: Ofrikhter I V , Ponomarev A B
Published: June 2021

Pile foundations are among the most common types of deep foundations. Predicting their draft is a fairly standard engineering goal. There are many techniques for this. Many methods for determining the settlement of piles are based on various empirical relationships. In particular, the cone penetration test allows you to determine the settlement and bearing capacity of a pile using the developed empirical dependencies. However, some models must be used to develop such correlations. This study proposes to use a slightly different approach. Instead of using a pile model and a set of empirical dependencies, it is suggested to use machine learning methods. Artificial neural networks are one of the machine learning methods. The article presents a description of the development of a neural network that allows estimating pile settlement using data from the CPT test.
Geotechnical monitoring bearing capacity boring pile foundations of bridge during permafrost degradation
Authors: Kudryavtsev S A , Valtseva T Y , Gavrilov I I , Kotenko Zh I , Sokolova N
Published: June 2021

The construction and operation of bridge foundations in permafrost conditions is associated with many problems, the most urgent of which is the degradation of the frozen state of soils due to the effect of solar radiation on the thawing process. Thawing of permafrost soils of the base significantly affects structures, the design of which does not provide for thorough protection from natural factors - first of all, these are railway bridges. The changing climate has a destructive effect on permafrost soils, which is destructive for infrastructure facilities operated in the permafrost zone. The aim of the given work is to increase the efficiency of systems that regulate the temperature regime of permafrost soils of the bridges foundations which are located on railways in permafrost regions.
Determination of an allowable value of internal uniform pressure on the underground horisontal working contour with a trapezoidal form of its cross-section
Authors: Bogomolov A N , Ushakov A N , Bogomolova O A
Published: June 2021

The paper presents the study results of the stress state at the contour points of an underground horizontal working carried out by the methods of the complex variable theory. This study is the basis for solving the problem of determining an allowable value of the uniform pressure transmitted to the contour of the working, with predetermined values of the depth of its laying. The condition proposed by the authors of the paper is used as a criterion of strength (stability), according to which the working’s contour strength is ensured if at any point the amount of the tangential normal stress does not exceed the tensile and compressive strength of the host soil (rock), i.e. σt
≤ σe
≤ σc
. As a result of the solution, an assessment of the stress distribution on the contour of an underground horizontal working has been made. The working has a cross-section in the form of a curved trapezoid, which is under the action of uniform all-round stretching of a given intensity with a varying depth and various values of the host mass lateral expansion coefficient. The allowable values of the tensile internal pressure on the contour of an underground horizontal working of a trapezoidal cross-section have been determined at the given values of its depth and a constant coefficient value of the lateral expansion of the host mass μ = 0.25. The materials presented in the paper can be used when choosing the maximum or minimum allowable depth of the working used as a storage facility for liquid or gaseous hydrocarbons.
Vertical-load design of a large-size bored pile
Authors: Gotman A L , Gavrikov M D
Published: June 2021

The results of experimental and theoretical studies of vertically loaded large-size (from 50 and more meters long) bored pile work features are presented. The results of testing the vertically loaded large-size bored piles with a diameter of 2m, a length of 55m and 65m in clay soils by the submerged jack method are analyzed. According to the test results, the features of the soil resistance formation under the pile tip and on the side surface are identified. On this basis, the need to design such piles according to the second soil limit state, taking into account the compressibility of the pile shaft is justified. The kinematic scheme of inclusion the soil base and the pile shaft into work under vertical loading is given. On this basis, a technique for calculating the settlement of a single pile and a method for determining the allowable load on the pile are developed. This load does not allow pile settlement to exceed the allowable settlement of the designed building. An example of a bored pile calculation by the developed method is given.
The form of the elastic core and areas of plastic flow base under the jucked stamp
Authors: Bogomolov A N , Bogomolova O A
Published: June 2021

The article provides the information about studies devoted to determining the position, shape and size of the elastic soil core and areas of plastic deformations formed in the soil foundation under the jucked stamp. Based on the results analysis of experiments carried out by third-party researchers and the results of calculations performed by the authors of the article, it was concluded that an elastic soil core in the form of a triangle is formed in the case when the indentation of a stamp is carried out into a base folded with loose ground, provided that φ>25-30° (this depends on the value of the lateral soil pressure coefficient), and the specific cohesion C is quite small. In cohesive soils, the vertical section of the elastic soil core has a form close to that of half an ellipse, half or a segment of a circle. The exceptions are the results of the experiments by Kaganovskaya S E, where a triangular elastic core was obtained for clay soil. All these facts are in satisfactory agreement with Prandtl’s design scheme, and therefore, the use of calculation methods based on it is justified only for sandy bases. To solve the problem of calculating the bearing capacity of soil foundations composed of various types of soils, methods should be created that are not based on hypotheses about the shape of the elastic core and areas of plastic deformation.
New pile foundation structures for swelling clay soils
Authors: Gabibov F G
Published: June 2021

The information on the basics of designing pile foundations on swelling clay soils is presented and analyzed. New designs of conical piles and those with a variable cross-section, in which the soil mass swelling is accompanied by the effect of pile pinching, have been developed. Moreover, new pile foundation structures with protective shells involving a calcium elastic rolling member and some rubbing elements like low-friction plastic and metal braces are proposed.
Influence of superplasticizer additive on the strength of cement stone during wetting–drying cycles
Authors: Dobshits L M , Nikolaeva A A
Published: June 2021

This article discusses the issues of durability of reinforced concrete structures exposed to drying–wetting cycles. Transport structures are under the constant wetting and drying cycles, but rarely completely dry out, as the saturation process occurs faster drying. Such cycles cause moisture migration inside the concrete, which leads to leaching of calcium hydroxide Ca (OH)2. The structure of the cement stone changes over time, and the dissolution of cement hydration products additionally leads to a strength decrease. Were tested the influence of the alternation of cycles of water saturation and drying of concrete on tensile strength, as the most sensitive characteristic to changes in the structure of the material. Since at present most concretes are manufactured using plasticizing additives, the tests were carried out with different content. The studies show that regardless of the amount of plasticizing additive in the samples, the flexural strength decreases. The compressive strength gradually increased, which is probably due to the ongoing process of hydration of the cement grains.
Multicomponent complex oxide media – the basics of the functional materials for electronic engineering: the selection of the promising compositions for assessing the ferrohardness
Authors: Andryushin K P , Dudkina S I , Shilkina L A , Andryushina I N , Rudskiy D I , Verbenko I A , Reznichenko L A
Published: June 2021

According to the optimal technological regulations, the solid solutions of two four-component systems based on lead titanate-zirconate and alkali metal niobates were prepared: (1-x) Na0.875Li0.125NbO3 – xPbTi0.5Zr0.5O3 (0.05 ≤x < 0.95, Δx = 0.025-0.10) and (1-x) Na0.875K0.125NbO3 – xPbTi0.5Zr0.5O3 (0.0 ≤x ≤1.0, Δx = 0.05-0.10). The electrophysical parameters of the solid solutions of these systems were determined and the degree of their ferrohardness and efficiency was assessed according to the main characteristics: the relative permittivity of the polarized samples, ε33T/ε0, the mechanical quality factor, Q
M, the coefficient of electromechanical coupling of the radial vibration mode, Kp, the piezomodule, |d
31|. It was shown that, depending on the chemical composition and the position of the solid solutions on the phase diagram of the systems, they can be characterized by different degrees of the ferrohardness and efficiency, which made it possible to select promising compositions: ferrohard ones – for the converters with high specific power (in step-down piezotransformers, piezoelectric motors, etc.) ); of the medium ferrohardness – for highly sensitive receivers of the ultrasonic vibrations (telemetry sensors, automatic control systems, etc.); ferrosoft materials with high efficiency – in the low-frequency devices (microphones, hydrophones, deflectors of the optical systems, robotics devices, etc.).
Structural, elastic and thermal properties of Laves phase Fe2Mo from first principles
Authors: Vasilyev Dmitry
Published: June 2021

In this work, structural, elastic and thermal properties of the Laves phase Fe2Mo (λ-) with the C14-type structure existing in the Fe – Mo system have been investigated using the quantum mechanical calculations within the frame of the density functional theory (DFT). The equilibrium lattice parameters, atoms position coordinates and average magnetic moment of atoms were calculated. The five independent elastic constants of the strain tensor were calculated by imposing small strains on the crystal lattice. Polycrystalline elastic parameters: bulk modulus (B), shear modulus (G), Young’s modulus (E), and Poisson’s ratio (v) were obtained by using the Voigt-Reuss-Hill (VRH) approximation. An assessment of anisotropy of elastic properties was carried out. The Debye temperature and anisotropic sound velocities were predicted. The calculated results were analyzed. The obtained results are useful to improve the understanding of the physical and chemical nature of the Fe2Mo phase.
Experimental study of plasticization and foaming of polymer materials in supercritical carbon dioxide
Authors: Minaeva S A , Epifanov E O , Minaev N V , Popov V K , Zimnyakov D A
Published: June 2021

A laboratory system for the development of new approaches to the experimental study of nucleation and formation of three-dimensional structures in nonequilibrium “polymer-supercritical fluid” heterogeneous systems has been designed and produced. The system is designed to conduct a comprehensive analysis of these processes at various stages starting from supercritical fluid plasticization of the initial polymer, followed by its subsequent nucleation and passage to the glass transition stage of the foamed polymer matrix, providing an opportunity for adequate interpretation.
Development of photometric analysis of structural images in relation to the study of nickel-chromium alloy
Authors: Ermishkin V A , Mikhailov D L , Minina N A
Published: June 2021

This work presents preliminary results of the study of a new nickel-chromium corrosion-resistant alloy “Solution-N” intended to replace the imported G-35 alloy, which is currently used for the manufacture of chemical reactor vessels. In view of the limited amount of smelted material, photometric analysis of structural images is widely used to study its structure and properties. Based on the results of the studies carried out, it is proposed to choose the optimal structural state of the alloy, which has the highest corrosion resistance in the temperature range 600-650°C. Corrosion tests are currently being carried out in the laboratory of the prospective customer.
Dielectric spectroscopy, piezoelectric and ferroelastic properties of solid solutions of the three-component system (1-x-y) NaNbO3 – xKNbO3 – yCdNb2O6 in the temperature range (10-330) K
Authors: Moysa M O , Andryushin K P , Kubrin S P , Andryushina I N , Reznichenko L A
Published: June 2021

A solid solution of the three – component system 0.8NaNbO3 – 0.15KNbO3-0.05CdNb2O6 was prepared by two-stage solid-phase synthesis followed by sintering using conventional ceramic technology. An experimental study of the dielectric, piezoelectric, and ferroelastic characteristics of the latter in the low-temperature range (10÷330) K. The conclusion is made about the expediency of using the obtained results in the development of functional ferroactive materials based on sodium – potassium – cadmium niobates and devices with their participation.
Influence of the sintering temperature on morphology of alloy germanium-tin nanoparticles synthesized by spark discharge
Authors: Lizunova A A , Borisov V I , Ivanov V V
Published: June 2021

Alloy GeSn airborne nanoparticles (NP) with the rate of atomic content of Sn to Ge 30 % were produced by spark discharge during simultaneous erosion of germanium and tin electrodes in atmosphere of argon of purity 6.0. Then NP were moved by gas flow to a tube furnace, which were mounted directly after discharge chamber, and sintered at temperatures from 25 to 750 °C. The change of morphology, element composition and crystal structure of NP were investigated using transmission electron microscopy (TEM) with energy dispersive X-ray analysis (EDX), aerosol spectrometer and Fourier-transform infrared spectroscopy (FTIR). Agglomerates of predominantly amorphous primary NP with the mean size of 7 nm were obtained at low sintering temperatures of the tube furnace (25 and 200 °C). High temperature (550 and 750 °C) flow-through thermal sintering of NP agglomerates resulted in production of individual crystal NP with an average size of 28 nm with various crystal structures.
On the diagnostic features of the gas-discharge visualization for the assessment of medicines
Authors: Shipko M N , Sibirev A L , Maslennikova O M , Stepovich M A , Nikonorova V G
Published: June 2021

The therapeutic efficiency of medicines containing the same active ingredient depends on the production technology, as well as the excipients included in the tablet and the type of shell. In this work, we consider some of the possibilities of using the gas-discharge visualization method based on the phenomenon of channeling electrons through a liquid medium to study aqueous solutions of medicines. The study was carried out on the example of the passage of kilovolt electrons through drops of solutions of the beta-blocker bisoprolol, produced by various pharmacological companies. We studied bisoprolol preparations without excipients and bisoprolol preparations with excipients. The obtained differences in the characteristics of the gas-discharge luminescence for the studied medicines open up prospects for assessing the quality and pharmacological efficiency of medicines, and, subsequently, for the individualization of medicines therapy.
Phases formation in cerium-doped hydroxyapatite
Authors: Petrakova N V , Nikitina Yu O , Egorov A A , Titov D D , Baranov O V , Barinov S M , Komlev V S
Published: June 2021

Cerium-substituted hydroxyapatites (Ce-HAs) with an estimated content of Ce3+ of 0; 0.1; 0.25; 0.5 mol. % were prepared by two different synthesis methods: precipitation from aqueous solutions of salts and mechanochemical synthesis. The powders after synthesis were heat-treated at 1250 °C to achieve well-crystallized phases. The X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive analysis (EDA), and dilatometry methods revealed that cerium ions didn’t not fully incorporate into the HA structure, but rather were transform to the CeO2 phase. It was attributed to the transition of Ce valency (III)→(IV) through the oxidation reaction under air conditions during materials heating. Two different synthesis methods provided similar phase composition of the obtained compounds, though different microstructure of the resulted ceramics. It was shown that cerium introduction prevents HA sintering during thermal activation, possibly due to contribution of large atomic mass of cerium ions and formation of cerium (IV) oxide at the crystal boundaries.
Si3N4 ceramics with sintering additive of MnO-TiO2
Authors: Kim K A , Lysenkov A S , Titov D D , Petrakova N V , Frolova M G , Ivicheva S N , Fedorov S V , Kargin Yu F
Published: June 2021

Ceramic samples based on Si3N4 were obtained and studied using a sintering additive in the MnO-TiO2 system of eutectic composition, which was accepted and applied to the surface of silicon nitride by the sol-gel method. Ceramic samples were obtained by hot pressing at 1650 °C and 1750 °C. Phase composition, thermo-physical and mechanical properties were studied. The microstructure of the resulting ceramics was also studied.
Sintering and properties of materials based on nanosized silicon nitride powder
Authors: Tomkovich M V
Published: June 2021

A high-density material (ρ = 3.28 g / cm3, porosity 1.4% by volume) based on nanosized silicon nitride powder was obtained by the method of liquid-phase sintering. The effect of compacting pressure on the density of sintered silicon nitride materials is shown. The process of material structure formation during sintering has been studied. The main physical and mechanical characteristics were determined: density, porosity and grain size of the solid phase, elastic modulus, flexural and compressive strength, crack resistance coefficient, Vickers hardness.
Physics of reological explosion
Authors: Oparina I B , Shienok V V
Published: June 2021

The paper presents the results of experimental research of patterns of relationship and features of reological explosion. Revealed and studied traces at materials, which were in contact with exploded bodies. Presented and analyzed rapid filming of this explosion. Established and described it’s mechanism.
The impact of a sintering additive from Al, Mg, Y-oligomer on the physicochemical properties of MoSi2 ceramic
Authors: Danilin K D , Titov D D , Lysenkov A S , Kargin Yu F , Konovalov A A , Petrakova N V , Gumennikova E A , Senina M O , Shcherbakova G I
Published: June 2021

We investigated the effect of a triple oxide additive (Al2O3-MgO-Y2O3) obtained by a new method on ceramics properties based on MoSi2. The ternary oxide was obtained from a ceramic-forming oligomer. Ceramic MoSi2 samples were obtained by hot pressing of molybdenum disilicide with ternary oxide 1, 3, 5, 10 wt% at 1650 °C and 30 MPa. The graphs of the dependence of density, bending strength and electrical resistance on the content of Al2O3-MgO-Y2O3 are presented. It was found that as the additive level was increased, the flexural strength increased to 89 MPa. The specific electrical resistance, depending on the oxide additive content, is extreme with a maximum for a composition containing 1 wt% Al2O3-MgO-Y2O3.
Structural features of metals and alloys formed in the process of selective laser melting
Authors: Bazaleeva K O , Tsvetkova E V
Published: June 2021

The features of the structure formed during selective laser melting (SLM) on the example of austenitic steel Fe-17%Cr-12%Ni-0.02%C (316L) and nickel alloy Ni-11%Cr-5%Co-6%Al-3%Ti-4%Mo-5%W-0.16%C-0.02%B are considered in this work. The structure formation occurs under conditions of ultrafast cooling rates from the region of the melt during laser treatment and subsequent thermal cycling during solidification of material adjacent regions. The following structural features are considered: hierarchical structure, heterogeneity of the alloying elements distribution, dislocation structure, macrostresses and crystallographic texture.
Effect of the synthesis temperature on the phase composition of Al2O3
Authors: Leonova Yu O , Sevostyanov M A , Mezentsev D O , Khayrutdinova D R , Lysenkov A S
Published: June 2021

This work is devoted to studying the effect of the synthesis temperature on the phase composition of Al2O3. Aluminum hydroxide was obtained by a reverse heterophase deposition method. This method makes it possible to obtain the purest hydroxide powder. For the synthesis, several different temperature regimes were selected in the temperature range from 250°C to 1100°C.
Non-traditional legumes in the soil-protecting crop rotation of the mountain zone of the Republic of North Ossetia-Alania
Authors: Tedeeva A A , Mamiev D M , Abaev A A , Tedeeva V V
Published: June 2021

Mountainous and sloping lands occupy one third of the territory of our country, more than 50% in the Republic of North Ossetia-Alania, and are a huge reserve for increasing agricultural production. Soil and climatic conditions on the slopes of the mountains and in the intermountain valleys make it possible to grow environmentally friendly products, to heal the seeds of agricultural crops from viral diseases. Increasing the production of agricultural products is one of the most important problems of agriculture. The mountainous territory of the Republic of North Ossetia-Alania is an important reserve for increasing the volume of agricultural production. About forty percent of the total area of the republic is concentrated here, most of which is characterized by favorable soil and climatic conditions. The development of agrotechnical, anti-erosion measures is one of the factors of preventing erosion processes in the soil and restoring soil fertility. The research was carried out in a mountainous area on mountain-meadow soils. According to the mechanical composition, it is middle loamy. The soil contains a high level of organic matter. It is moderately provided with hydrolyzable nitrogen and mobile phosphorus, and is highly provided with potassium. Studies have shown that these soils are favorable for the cultivation of perennial non-traditional leguminous grass species-eastern galega and crown vetch and the obtaining of products with high feed rates. The greatest soil protection effect from water erosion in the crop rotation was possessed by perennial leguminous grasses cultivated on a herbage – clover with timothy, eastern galega and crown vetch, which have a coefficient of soil protection from water erosion. In the soil-protecting six-field crop rotation eastern galega and crown vetch improved the structural and aggregate composition of the soil, the water resistance of soil aggregates, density and pore volume, also they increased soil fertility.
The use of herbicides in the cultivation of corn
Authors: Tedeeva A A , Mamiev D M , Tedeeva V V , Khokhoeva N T
Published: June 2021

The article discusses the results of studying the effectiveness of the use of new generation herbicides, both soil, applied before the emergence of maize seedlings – Merlin (150 g/ha); Cassius (50 g/ha), and for seedlings – Elumis (1.0-2.0 l/ha), on crops of three maize hybrids. The studies were carried out in the conditions of the foothill zone of the Republic of North Ossetia-Alania, on leached chernozems. The objects of research were different corn hybrids in terms of precocity (the originator of the KBNIISKH).) – Kabardinskaya 3812 (late-repining), Camilla SV (mid-late), a variety of white-grain food corn Bella 451, which is cultivated not only to obtain varietal seeds, forage, but also to meet the food needs of the indigenous population. The national cuisines of most of the peoples of the North Caucasus use flour and cereals made from white-grain corn. In this regard, it is very important to introduce into production, along with yellow-grain forms used for fodder, highly productive varieties and hybrids of white-grain corn for food purposes. Middle-late variety, food grade. As a result of the conducted studies, it was found that the treatment of the soil with the herbicide Elumis was more effective than the check. We had the following grain yield: Kabardinskaya 3812 hybrid – 8.7 t/ha, on the nonfertilized ground, 12 t/ha – on the fertilized ground, Camilla SV hybrid – 8.5 t/ha – on the nonfertilized ground, 11.7 t/ha – on the fertilized ground, and Bell 451 hybrid – the yield on the nonfertilized was 7.0 t/ha, on the fertilized ground – 9.9 t/ha. The response in yield of Kabardinskaya 3812 hybrid to the application of herbicides was more effective than other hybrids studied.
Development of a method for testing the wear resistance of friction pairs based on the synthesis of the method of M. V. Lomonosov with the improved method of artificial bases
Authors: Davydov R V , Tikalov A V , Chulkin S G , Breki A D , Efremov L B , Rud’ V Yu , Bykova N N , Valiullin L R
Published: June 2021

The article is devoted to improving the method of testing the wear resistance of friction pairs in a wide range of hardness by embedding a roller into a flat surface of the material under study (sample), first proposed by M. V. Lomonosov. The formula for estimating the volumetric wear resistance from linear depending on the specific pressure is proved. According to the new method, the relative wear resistance of materials in a wide hardness range was evaluated.