bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving the reliability of FRP bars tests by increasing the adhesive strength in specimen anchor
Authors: Kazakevich Tatyana , Mamedov Shirali , Nizhegorodtsev Denis , Klevan Vadim
Published: August 2020

Test methods for reinforcing steel is not suitable for fiber reinforced polymer (FRP) rebars because it can cause destruction of the edge zones of the samples. The polymer matrix and fibers are not able to resist compression across the fibers. Existing test methods for FRP rebars do not contain information about the equipment and composition of the adhesive composition. The purpose of the study is to clarify the adhesive composition and design of the FRP specimen anchor. Methods. There were experimental studies of fiberglass reinforcement polymer rebars samples carried out. The following factors varied: the proportion of the components of the adhesive composition; the area of the adhesive contact of the FRP specimen anchor. Results and Discussion. The proportion of epoxy glue and quartz sand providing the test of automatic transmission is determined. The influence of the thread on the inner surface of the FRP specimen anchor on the adhesive strength in the contact zone «adhesive composition-steel» is estimated. A universal three-dimensional model of the centering plug for manufacturing using additive technologies has been developed. Conclusions. The results of the investigation can be used to upgrade the FRP rebars test methods.
Analysis and optimization of the bearing capacity of connecting wooden structures with application of dowel type self-drilling
Authors: Phong Tran Quoc
Published: August 2020

The multiple shear connection with slotted-in steel plates and dowel-type self-drilling is a very efficient timber connections for frame and truss. It is used in practice, due to its high capacity and faster construction method. However, when the complex connection and many parameters affect the bearing capacity, instead of a ductile mechanism, brittle failure may govern its capacity. To achieve the desired working connection, the relationship between the connection configuration parameters is established but no standard specifically with this kind of connection. A series of parameters changes affecting the bearing capacity of the connection are given. Calculate and compare with many previous research methods in ductile failure modes to assess their prediction accuracy and optimal connection. A model for the optimization of the ductile failure mode for the multiple shear connections with slotted-in steel plates and dowel-type self-drilling is then proposed.
Constructive device for sediment flushing from water acceptance structure
Authors: Aynakulov Sh A , Karimova Kh , Shakirov B , Alibekov S , Mamajonov M
Published: August 2020

The article discusses a constructive solution for sediment flushing from the water acceptance chamber of the pumping station, which is solved by using a guide wall raised above the bottom of the chamber. The wall is installed at a distance L0 = (2.6 … 3)Di from the inlet of the suction pipe of the pump at an angle of 25.30° relative to the bottom of the chamber. Due to the installation of an inclined guide wall, the level difference is Δh = (0.08 … 0.1)Di, where Di is the diameter of the inlet of the suction pipe. To reduce the difference in water levels Δh = 9 … 11 cm from the action of the guide wall, through holes of rectangular cross-section are made in it with a width of Di and a height of 0.2Di. If the drag coefficient ξ for a chamber with sediment is ξ = 0.61, when washing off sediment it is equal to ξ = 0.491, so the pump flow from 424 l / s increased to 476 l / s, i.e. increased by 52 l / s. A comparative analysis of flushing sediment from the water acceptance chamber under laboratory conditions is compared with the results of the analysis under field conditions. According to the developed design, the pump efficiency increased by 5.9%, and the flow rate increased by 12.2%.
Development a mathematical model of a water-salt balance on irrigated lands of the Sirdarya area
Authors: Ergasheva D , Kasimbetova S , Aynakulov Sh , Sharipov D , Khamraeva Sh
Published: August 2020

The article presents the results of field studies and analysis of the parameters of the input and expenditure components of the water-salt balance, which makes it possible to assess the reclamation state of irrigated lands. Directly in the field, using the measurement determined the values of the input and expendable components of the water and salt balance, a tendency to improve or worsen the reclamation state of the irrigated lands of the Shuruzak massif and the Saykhunabad district of the Syrdarya region. The general water balance, the balance in the aeration zone and groundwater was compiled. Determination of water and salt balance in the aeration zone of soil and groundwater leads to the creation of optimal water-air and nutrient regimes for the development of crops and high yields. To determine the water and salt balance on the irrigated lands of the Saykhunabad region, a mathematical model was developed for the first time, based on which it is possible to predict changes in the water, salt regimes and the regime of groundwater in the irrigated massif. Their regulation is very important for determining practical measures to manage this regime in order to save irrigation water and improve the reclamation state of irrigated lands.
Optimal order of construction of facilities in complex development with minimal additional costs
Authors: Mailyan Alexander , Korol Elena , Petrosyan Rima , Antoniadi Diana
Published: August 2020

Stream methods of work during the construction of a group of construction projects provide the selection of priorities in the optimization of calendar plans. This can be a reduction in the duration of construction or resource provision in time. Due to the change in the arrangement of objects in the stream, the total duration of the work on the entire object complex can be changed. By the methods of organizational and technological modeling, a rational sequence of work is selected taking into account the optimization of resource costs. When constructing a complex of objects, a comparative analysis of various combinations of grouping objects, using the methods of decomposition and aggregation, allows you to carry out a numerical rating of various parameters of the work, such as duration, labor, providing material and technical resources, etc. This ensures the optimal ratio between the duration of the construction of the object complex and additional costs that arise during the parallel construction of several objects. A graphical interpretation of the choice of the optimal organizational and technological solution is work schedules at the facilities, allowing differentially and integrally to evaluate the development of material and technical resources.
Sound insulation of PVC windows at negative outdoor temperatures
Authors: Konstantinov A , Verkhovsky A , Lyabakova E
Published: August 2020

The PVC windows using experience in the climatic conditions of the Russian Federation shows that their profile elements are subject to temperature deformations under the influence of the temperature gradient of outdoor air and indoor air. This physical phenomenon is observed both in the summer and winter operation period. In this article we study the influence of external air negative temperatures into the sound insulation of PVC windows. The research was performed on a standard PVC window in a climate chamber with acoustic equipment. The PVC window sound insulation measurements were carried out at the following temperatures inside the cold compartment of the climate chamber+20 °C, 0°C, -5°C, -20°C (at a constant temperature in the warm compartment of the chamber + 20°C). It is established that the reduction of PVC windows sound insulation begins to occur only at outdoor temperatures below 0 °C. The sound insulation of PVC window at an outdoor temperature -20°C is 3 dB lower than the sound insulation of the same window, determined under standard conditions (+20 °C). Obviously, existing methods of calculation of sound insulation of PVC windows it is necessary to adjust in terms of operational ambient temperatures and design features of the windows.
Strength of wood reinforced with a polymer composite for crumpling across the fibers
Authors: Lisyatnikov M S , Glebova T O , Ageev S P , Ivaniuk A M
Published: August 2020

A method for strengthening beams on a support with a polymer composite based on fiberglass and an epoxy matrix with the inclusion of carbon nanotubes in its composition is proposed. To prove the effectiveness of reinforcement and determine quantitative and qualitative characteristics, experimental studies were conducted on standard wooden samples with and without reinforcement. Before conducting the experiment, it was planned in order to achieve maximum measurement accuracy with a minimum number of experiments and maintain the statistical reliability of the results. As a result of planning, a multi-factor formula was obtained for determining the strength of the sample depending on any combination of three variable factors: the reinforcement coefficient, the quantitative component of carbon nanotubes, and the curing temperature of the composite. The tests were performed under normal conditions. As a result of compression tests across the fibers of experimental samples, it was found that the strength limit of reinforced samples in comparison with wooden ones without reinforcement increases to 39 %, and the destruction is plastic.
Foam fiber-reinforced concrete: technology and methodology of selection of the composition
Authors: Zhukov Aleksey D , Bessonov Igor , Efimov Boris , Medvedev Andrey , Poserenin Alexey
Published: August 2020

Disperse reinforcement of the mineral matrix in concrete technology makes it possible to manufacture structures of complex configuration, to solve problems of frost-resistance of products, minimize shrinkage deformations. The technologies of application of dispersed reinforcement of a concrete matrix with the help of synthetic, mineral and metal fibers has been developed. Perspective is considered reinforcement with basalt fiber - material resistant in alkaline environments of cement stone and having high adhesion to the mineral matrix. Foam concrete in industrial conditions is produced either in a one-stage or two-stage scheme. The technology of foam concrete of two-stage manufacturing has been studied quite well and its formulations have passed a wide approbation. The novelty of the research is the integration of basalt fibers into the concrete mix as a dispersive reinforcing component. This aspect has been given special attention in research. It is established that the consumption of basalt fiber affects both strength and density of cellular concrete products. The length of basalt fiber affects only the strength of products. As a result of the system analysis of penofibrobeton technology using the methodology of mathematical planning of a multifactorial experiment, obtaining results based on statistical analysis and optimizing these results, a mathematical model has been built and a technique has been developed of selecting of the composition penofibrobeton in densities from 400 to 600 kg/m3.
Qualitative risk approach in the construction of electric power facilities
Authors: Borkovskaya Victoria G , Skrynnik Anton
Published: August 2020

The main issue of the study is the problem of risk management in the planning and implementation of projects for the construction of electric power facilities. Projects for the construction of such facilities, which are characterized by high technological complexity and uniqueness, at the stages of design, equipment delivery, construction and commissioning, face unforeseen circumstances and, often, the project management is not ready to solve the problems that have arisen. The purpose of this article is to describe a methodology for qualitative risk assessments in relation to projects for the construction of electric power facilities with the determination of levels of responsibility, analysis of stakeholders, and distribution of risks among stakeholders. The proposed method can be used for risk analysis and making informed decisions at the stages of planning and implementing projects for the construction of electric power facilities.
Composite materials based on non-recyclable polyethylene
Authors: Saporovskaya T Y , Prohorov S V , Timakov E A
Published: August 2020

In this paper, the possibilities of creating composite materials based on cross-linked polyethylene (XPE) were investigated. The environmental benefit of recycling such polyethylene is to free up space for buildings that are now occupied by landfills. The influence of polyethylene, previously considered non-recyclable, on the strength characteristics of concrete is shown. In the course of the work, waste from the existing chemical industry was used, with varying particle sizes (0.5-15 mm). The analysis of patent information on the utilization of polyethylene in construction materials. Using mathematical planning methods, the compositions of composite materials are optimized. The volume of solid waste of non-recyclable plastic is more than 1.3 billion tons. Its decay period in the natural environment is more than 400 years. There is no world experience in the use of such waste, so the problem of its disposal is more than relevant. Thanks to the results obtained, it is possible to significantly reduce the degree of environmental pollution by waste of chemically cross-linked polyethylene, and get a new composite material for construction, a wide range of applications. The economic justification of the developed technology being introduced into mass production is presented.
Rayleigh surface waves in assessing the state of metal structures
Authors: Erofeev V I , Rodyushkin V M , Ilyakhinsky A V , Nikitina E A , Khazov P A
Published: August 2020

The work is devoted to the search of a method of ultrasonic sounding for identification of the material state, permitting to refer the diagnosed structure to the class of structures, whose state is connected with the appearance of plastic deformations. The study has shown the application of surface Rayleigh waves allows to estimate the stress-strain state of metal structures in the field of both elastic and plastic deformation.
Characteristics of heat insulating foam aluminum silicate under change of heat treatment parameters
Authors: Khristoforova I A , Khristoforov A I , Timakov E A
Published: August 2020

In case of heat insulation, work material choice depends on the type of protected object, materials available and usage convenience. Durability match between heat insulation and basic building material lies at the core of insulation choice. Foam glass and its derivatives (e.g. foam aluminum silicate) have properties meeting the strictest requirements of today. These rigid highly porous foam insulation materials have closed cell structure, representing solidified glass foam with either polyhedral or rounded cells. For these reasons, usage of highly efficient environmentally friendly foam insulation materials is so relevant today. A process was developed for batch heat treatment using local natural raw materials found in Vladimir region. The process consists of components joint grinding, produced batch preparation, blank pressing, foaming and heat annealing, and property research for produced materials. It turns out that foaming parameters are strongly intervened with batch composition, therefore requiring constant adjustment for each batch composition change. Researches show that specific heat treatment parameters provide foam formation with high foaming ratio and closed pore structure. Furthermore, we managed to create a foam aluminum silicate having the following features: density 130-350 kg/m3, coefficient of thermal conductivity 0.07 – 0.11 W/m·K, compressive strength 0.7 – 3.0 MPa.
Wall materials based on complex binders and organic aggregate
Authors: Zakrevskaya L V , Gavrilenko Andrei , Andreeva Ksenia , Lubin Petr , Kapush Ilya , Udin Igor
Published: August 2020

The technology of hards concrete developed in this study differs primarily by the binders - semi-burnt dolomite, related to magnesia cements. Grouting fluid is bischofite (MgCl2) or magnesium sulfate (MgSO4), density 1.2 g/cm3. One of the ways of strengthening and adding new properties to hards concrete, which can significantly expand its application domain, is an introduction of chrysotile to the concrete composition. The best specimen have density 570-585 kg/m3, strength 14.5 - 15.1 MPa and low thermal conductivity (0.065-0.074) W/(m·K), what allow them to serve as structural and thermal insulation material. Sound absorption coefficient is from 0.17 to 0.6 (at audio frequencies of 125-2000 Hz). Frost resistance exceeds 50 cycles, water absorption is 40-50%, shrinkage is less than 0.4%, fire stability is 0.75-1.54. Based on the results obtained, it can be concluded that the material is most applicable in low-rise construction. The developed material will solve the problem of utilizing of industrial hemp waste from textile production and dolomite waste in the form of a magnesian binder, thereby reducing the cost of the material in compare with existing world analogues.
The two-factor destructions model of the composite
Authors: Varlamov A , Shafranovskaya T , Rimshin V , Kurbatov V
Published: August 2020

The article examines the destruction of a composite using a diamond disk. The composite structure is adopted as a two-factor symmetric model, in which the composite grains are represented as balls in the matrix body. A feature of the design is the symmetry of the crack along the two main planes. A model of interaction of a diamond disk with a composite is developed. The destruction of composite models was carried out by cutting the individual bands. Cutting revealed the cyclical nature of the energy characteristics of the fracture models. The cyclic nature is described by a sinusoidal wave of structure destruction. The simulation results provide a formula for the composite structure, which is described using the energy characteristics of cutting. The structure and parameters of the fracture model obtained during cutting allowed us to fully describe the composite structure model. The results of modeling show that it is possible to fully describe the model of a concrete composite using only the energy parameters obtained during cutting of the material.
Principles of creating new alloy compositions for the production of cast protectors
Authors: Kechin V A , Kireev A V , Lyublinski E Y
Published: August 2020

Aluminum protectors are used in cathodic systems for protecting metal structures from electrochemical corrosion. The materials of the article are devoted to the selection of elements for alloying aluminum, based on the analysis of physicochemical, technological and electrochemical characteristics of the alloy base and elements of the periodic system named after D.I. Mendeleev. Zn, Mg, Mn, Ti and Zr were selected as the main alloying components by the tendency of elements to alloy formation and to obtain a homogeneous structure, taking into account their effect on the anodic activity and resistivity of oxides on the metal surface. The obtained research results are in good agreement with the well-known international standards for the chemical compositions of aluminum tread alloys, for which magnesium, zinc, and manganese are present as the main alloying components. For experimental studies, Mg, Zn, Mn were chosen as alloying additives, and Si, Fe as impurities. The optimal the concentration range of the aluminum alloy will be as follows: for zinc, 3.6-5.4; for magnesium, 0.55-1.05; for manganese 0-0.3. The content of Si and Fe in the alloy is limited to 0.06 and 0.01%, respectively. The maximum value of the CUE - 75.78%.
Low heat concrete with ground granulated blast furnace slag
Authors: Barabanshchikov Yu , Usanova K , Akimov S , Bílý P
Published: August 2020

The subject of the research is a concrete with partial replacement of cement with an increased amount of ground granulated blast furnace slag to reduce heat release of concrete for the structures of the Akkuyu Nuclear Power Plant (Iskenderun, Turkey). The concrete was tested for heat release, compressive strength and shrinkage. Several mixes with partial replacement of cement by the slag from «Iskenderun Demir ve Çelik A.Ş.» were used for testing. The heat release is reduced by up to 50 % and the loss of strength is not more than 36 %. This is the result of an increase in the slag content in the mixed binder (cement + slag) and a decrease in the cement content. The optimal slag content in the mixed binder is 25 %. There is an increase in concrete strength by 3-4 % and a decrease in heat release by 13 % compared to the cement binder. All tested concrete mixtures with the cement replacement by the slag have a decrease of the heat release, which is greater than a decrease in the concrete strength. The cement replacement by the slag leads to an increase in autogenous shrinkage. If the binder contains 50 % of the slag, the highest value of the autogenic shrinkage is observed. This value is approximately twice greater than the shrinkage of concrete with the cement binder. If the binder contains 75 % of the slag, the shrinkage is less. The replacement of the cement content by the slag is recommended to reduce the heat release of concrete, in order to increase its thermal crack resistance.
Evaluation of quality parameters of the torque transmission connections of the multi-purpose machine spindle joints
Authors: Il’inykh Viktor , Pichuev Egor
Published: August 2020

The article presents the results of theoretical studies of a multi-purpose machine when assembling an HSK spindle-mandrel connection for accuracy, contact stiffness and strength. Studies were based on the developed original mathematical program complex for assessing the quality parameters of machine connections. They have been carried out with respect to HSK spindle-mandrel connections under conditions of multiple tool changes. Simulation of the coupling of connection parts for different values of the fastening (assembly) forces showed that HSK-type connections have a static uncertainty of basing under external loading conditions. Analysis of the stress-strain state of the connection joints was based on the finite element method when using software in the FEMAP 11.1 with NX NASTRAN. It showed that an unorganized change of bases occurs under the influence of external conditional load. It has been established that for tool mandrels of the HSK-63 type with a fixing force of 900 to 23000 N, the elastic displacements at the end of the mandrel vary from 1.5 to 0.6 μm under the condition of an external conditional load of 1732 N and, accordingly, from 8.0 to 2.5 μm with an external load of 6070 N. It was established that with a limiting value of the mandrel clamping force equal to 23000 N under conditions of external loading an unorganized change of bases occurs, namely: the end faces of the contact of the tool mandrel and the spindle are pressed, which reduces the geometric accuracy of a multi-purpose machine with a CNC.
Thermal insulation materials based on polyurethane foam modified by the polymethylphenylsiloxane
Authors: Smirnov K V , Chuklanov V Yu , Smirnova N N
Published: August 2020

In this work, the modification process of thermal insulation materials based on polyurethane foam by the organosilicon polymer polymethylphenylsiloxane was studied. The current state of thermal insulation materials based on polyurethanes problem and ways to improve the thermal and operational properties of foamed polyurethanes, such as maintaining the stability of characteristics under the influence of adverse factors, reducing moisture absorption and water absorption, were also analyzed. The influence of polymethylphenylsiloxane on the morphological characteristics and density of the resulting foams was studied. It was found that the introduced modifier affects the density of the resulting foam materials slightly. In this case, the introduction of an organosilicon product regardless of the ratio of the initial components leads to a decrease in water absorption. Studies have shown that the introduction of an organosilicon modifier in an amount of 2.5-5 m. h. leads to an increase in the heat resistance of the material. The heat resistance of modified samples increased by an average of 30-40 °C. Thus, the conducted research showed a real possibility of using the developed modified polyurethane foams for thermal insulation of industrial and civil objects.
Strain state agrogenic soil under its interaction with a deep ripper
Authors: Rashidov T , Djuraeva N B , Atamirzayev M , Normuminov B
Published: August 2020

The cultivated soil environment changes its structure and is deformed; therefore, the considered model of the processes of interaction of the working body with soil remains understudied. The influence of soil criteria on the working body behavior can be taken into account through its density and tensile strength. To describe the movement of the soil near the leg during finite deformations, a plastic medium model proposed by academician Kh.A. Rakhmatulin and simplified equations obtained on the basis of the hypothesis of flat sections were used. When using the model of linearly elastic and compressible plastic medium, the resistance forces of the soil medium are determined when the legs of the subsoiler, presented in the form of a circular cone, move. It has been established that the magnitude of this force substantially depends on the type of contact conditions between the body and the soil, and its greatest value is achieved in the case of continuous motion. The dependence of the resistance force on time is obtained. According to the results of graph analytical studies, it is obvious that at the initial stage, while the contact area of the circular cone with the soil is variable, the resistance force depending on time changes according to a parabolic law, and then it remains constant. In the case of the movement of the subsoiler leg at a constant speed, it was found that, depending on the coefficient of internal friction and soil traction, a zone of increased soil density can form near the working body of the cultivator, where there is a significant increase in resistance force. With an increase in the angle of internal friction, a slight decrease in the resistance force is observed. The calculations were carried out based on the methods of mechanics of a deformable solid, soil mechanics, and were performed in the Maple-8 programming environment.
CFRP composites for strengthening wooden structures
Authors: Gribanov A S , Strekalkin A A , Kudryatseva A A , Zdralovic N
Published: August 2020

The purpose of this work is to study the strength of wooden beam structures with local modification of wood in the compressed zone. To achieve this goal, the physical and mechanical characteristics of modified wood were determined using modifiers based on ed-20 epoxy-diane resin, urea-formaldehyde resin, and dimethacrylic polyester. The best physical and mechanical characteristics were obtained for samples using dimethacrylic polyester: the ultimate strength was 84 MPa, the elastic modulus was 21 GPa. The increase in strength compared to solid wood was 46%, and the increase in the modulus of elasticity was 54%. Tests of beam structures with a span of 4.5 m and a cross section of 100×200 mm with local modification of wood in the compressed zone with a polymer composition based on dimethacrylic polyester were carried out. The increase in the strength of beams with local modification in the compressed zone compared to solid wood was 11% within the design loads, and the increase in stiffness by 18%. The “load-strain” relationships are constructed based on the test results. It is established that the greatest effect can be achieved when using external reinforcement systems together in a stretched zone by reducing the influence of defects and defects in beam structures and local modification of the extremely stressed compressed zone.
Influence of laser treatment mode on the friction coefficient and wear of bearing steel
Authors: Morozov Valentin , Gusev Vladimir
Published: August 2020

The article considers the influence of input factors of the laser processing: the radiation power, the longitudinal feed of the laser beam and the distance from the protective glass of the focusing head to the workpiece on the friction coefficient and absolute wear of steel SHH15SG. The greatest influence on the output parameters (friction coefficient and absolute wear) has the power of laser radiation, as it increases, the wear of the surface layer decreases. The obtained multi-factor models and graphical interpretation of the experiment results allow us to assign a laser treatment mode that provides the demanded wear of the treated surface layer of bearing steel. The developed method of assigning the laser processing mode reduces the auxiliary time of the technological operation and eliminates the need for additional experiments in production conditions. The results of the research are useful for manufacturing enterprises that implement laser processing processes, as well as for design organizations that develop modern laser equipment.
Multiple-factor model of hardness of steel 40H13 after laser processing
Authors: Gusev Vladimir , Morozov Valentin , Gavrilov Dmitry
Published: August 2020

The multiple-factor experiment is planned and made, and the hardness of the chromic steel 40H13, which is subjected to laser processing on a multibeam laser complex, is determined. Samples in the form of a cylinder 7 mm long and with a diameter of 30 mm are exposed to laser processing. Hardness of the processed surface layer of samples was measured by means of the Micro-Combi Tester installation of CSM Instruments (Switzerland). The independent entrance factors of process, which significantly impact on operational indicators of the processed surface layer, are chosen: power of laser radiation, longitudinal feed of laser beam and a distance from protective glass of a focusing head up to the processed surface. As a result of performance of the plan of a multiple-factor experiment and statistical data processing of a planning matrix the regression equations, which connect the optimization parameter with independent factors, having the interactive and dominating impact on formation of physic-mechanical characteristics of quality of the processed surface layer are received. On the basis of the received multiple-factor model and its graphic interpretation the appointment and optimization of modes of the laser processing, which provides the required values of hardness of a surface layer, is possible.
Dehydration factor upon activation of building sand by ultraviolet radiation
Authors: Pavlov A N , Gol’Tsov Yu I , Mailyan L R , Stel’Makh S A , Shcherban’ E M
Published: August 2020

The analysis of the influence of ultraviolet irradiation of building sand, which is a filler in a concrete mixture, on the dependence of the strength of concrete on the content of the filler. With an increase in the sand content due to the hydrophilicity of the surface of its particles in the mixture, the amount of free water necessary for hydration of the cement and the formation of cement stone decreases. Along with a decrease in the content of binder cement, this factor is an additional reason for the decrease in concrete strength with increasing sand content. Ultraviolet irradiation leads to dehydration of the surface of sand particles and the appearance of hydrophobic centers. With the increase in the hydrophobicity of sand in the concrete mixture, the content of free water available for cement hydration increases, and the strength of the cement stone increases. The change in the hydrophobicity of the surface of sand particles depending on the irradiation time is nonmonotonic. Therefore, there is an optimal ultraviolet activation mode that provides the greatest increase in concrete strength.
Deep levels model identification in semiconductor barrier structures
Authors: Krylov Vladimir , Tatmyshevskiy Konstantin , Bogachev Aleksey
Published: August 2020

Semiconductor barrier structures are essential elements of modern integrated electronics. The band theory explains properties of barrier structures using deep levels in the semiconductor band gap. The relentless interest in studying the characteristics of deep levels is due to practical needs, ambiguous interpretations and scatters of experimental results obtained by different researchers. In order to increase the accuracy of the measurements, a modified capacitive deep-level transient spectroscopy technic of has been developed. A mathematical model of the hardware transformations of the barrier structure capacitance transient signal is developed and provided in this article. The model considers the nonexponentiality of the capacitance transient and the spectrometer hardware transformations nonlinearity. There are the results of the deep levels experimental studies in silicon diodes and the model parametric identification. The technic makes it possible to reduce by five or more times the six-sigma confidence interval for the discrete deep level activation energy determining in comparison with the round robin test results of ASTM F978-02.
Optimization of laser melting parameters of martensity-aging steel powder
Authors: Voznesenskaya A A , Kochuev D A , Kireev A V , Zhdanov A V , Raznoschikov A S
Published: August 2020

In this work, we investigated the possibility of manufacturing parts by selective laser melting of heat-resistant steel. The study of the structural-phase composition of the powder material by X-ray spectroscopy was carried out, and the particle size distribution was studied by scanning electron microscopy. Powder material was melted at an industrial facility for selective laser fusion, and the parameters of laser melting were optimized for experimental samples. Information on the nature of the current melting processes was obtained as a result of analyzing the geometric characteristics of laser irradiation zones. The structure of the formed material, pores and microcracks were revealed using metallographic analysis.
Topological layered nanostructures with controlled functional characteristics induced by laser radiation on a solid surface
Authors: Arakelian S M , Evstyunin G A , Kucherik A O , Bukharov D N , Khudaberganov T A , Zhirnova S V , Shamanskaya E L , Butkovsky O Ya
Published: August 2020

Models of the formation of roughnesses on the surface of materials and the movement of distributed flows in their presence are considered, which ultimately determines the functional properties of such topological materials of different compositions induced by laser radiation. The paper also presents simulation of crystallization of complex structures from a melt with an analysis of the morphology of the resulting crystalline structures, and shows examples of the occurrence of fractal dendritic formations. Different types of morphology are induced depending on the energy of the laser radiation and the duration of the heating; determining the final state of objects with the desired functional and structural characteristics. Using the methods of cellular automata, the models were obtained for both the distribution of crystallization centers and the growth of an individual cluster under the influence of diffusion mechanisms. The relationship between the resulting morphology and the modified parameters of the models used is analyzed.
Q-switched mode in laser ceramics with Cr4+ for technological surface cleaning
Authors: Kiselev Alexey V , Pankov Mikhail A
Published: August 2020

A compact solid-state laser based on a Nd:YAG (1 at. %) ceramic active media in the Q-switched mode was studied. Ceramic YAG elements with different concentrations (0.1 to 1 at.%) of Cr4+ doping were used as a Q-switches, 50 to 500 ns pulses were registered with the high energy single pulse. Transparent ceramic obtained by thermosetting sintering. A laser scheme is proposed with a pulse duration and energy setting that contains a composite element for combining the properties of the studied samples of transparent ceramics in one volume. This scheme allows you to implement a compact laser to clean the surface of various materials (glass, concrete, plastic, steel, etc.) from contamination.
Measurement of laser-induced dynamic structures on the surface of materials in a real time scale
Authors: Kazaryan Mishik , Galkin Arkady , Evstyunin Grigorij , Zhirnova Svetlana , Shamanskaya Elena , Arakelyan Sergei
Published: August 2020

The processes induced by laser radiation in the region of its interaction with matter are characterized by a high development rate and exclude direct contact of measuring detectors in the interaction region. The opportunity of structural adjustment of the irradiated surface of the material requires recording the temporal characteristics of these dynamic processes, which essentially determine the structural surface phase transitions in a heterogeneous medium. Therefore, for their diagnostics the highly sensitive, non-contact and inertialess registration methods are required. We used promising in this aspect optical recording methods based on the two channel scheme, i.e. the pump-probe techniques: the power pump laser and additional/probe laser radiation (brightness amplifies) to measure the development of nonlinear dynamic processes on the solid surface under laser radiation. The approach in frame of work of the such unified intelligent laser technological system results in control in time of processes of both laser thermal hardening with corresponding characteristics and generation of the spatial structures of different types on the surface of metallic units. We demonstrated some results for the laser technological processing with powerful laser radiation of a metal surface.
The melting regimes induced controllable by laser radiation on the surface of solids with the diagnostics of arising micro-nanostructures and hydrodynamic instabilities
Authors: Bukharov D N , Kucherik A O , Osipov A V , Antipov A A , Arakelian S M
Published: August 2020

We applied a controlled method for producing nanostructures on glass substrates. We made detailed measurements to control the resulting micro-and nanostructures using as the principal example of surface modification of glassy carbon compositions under laser irradiation. The properties of the samples after laser irradiation were studied using atomic force microscopy (AFM) with an accuracy of about 10 nm in the scanning plane. The results of probing the material modification by the AFM images of its surface have been considered in frame of the nonlinear hydrodynamic mathematical approach and computer simulation.
Granular dynamic structures of different topologies on the surface of solid materials; control of their distribution by laser treatment
Authors: Bukharov D N , Arakelian S M , Butkovsky O Ya , Evstyunin G A
Published: August 2020

The topic is focused on the technological features of the laser radiation action on the surface of metals to study various modes of formation of granular structures, which ultimately determine the functional and structural properties of products being under laser treatment. It is presented the results and algorithms being useful to predict the development of new technological processes on the material surface induced by laser radiation with an appropriate choice of key control parameters for the corresponding phenomena.
Vehicle oscillation taking into account the rheological properties of the suspension
Authors: Yusupov Majid , Rahkmankulova Barna , Ziyaeva Sholpan , Kushaev Akobir
Published: August 2020

The forced oscillations of a four-axle vehicle with a double spring suspension are considered. The motion of a system with six degrees of freedom can be represented with sufficient accuracy by a system with two degrees of freedom. Therefore, the body of the vehicle has two degrees of freedom: sideways movement and wagging (jumping and galloping carts will be neglected). It is assumed that the rheological properties of the spring (suspension) are different and obey the hereditary theory of Boltzmann-Volterra viscoelasticity. As the core of heredity, the Koltunov-Rzhanitsyn core is used, which has weakly singular features of the Abel type. Effective computational algorithms for solving problems based on the use of quadrature formulas have been developed. For numerical calculation, a computer program has been compiled, the results of which are presented in the form of graphs. The influence of the rheological properties of the suspension on the forms of vertical and angular movement of the body is studied. It was found that due to the suspension viscosity, the amplitude of vertical and angular oscillations decreases and the frequency increases.
A method to perform float-and-sink test for separation of coal samples of various densities and determination of ‘Probable Error’ and ‘Imperfection’
Authors: Pradhan Sushobhan , Mohanta Satyabrata
Published: August 2020

This article presents a detail experimental procedure to perform float-and-sink tests for classifying coal samples according to their densities. Moreover, this article emphasizes obtaining ‘partition curves’ for three different coal samples (heavy media bath, big barrel and small barrel), which helps in evaluating and demonstrating classifier performance. Calculations of independent variables such as ‘Probable Error’ and ‘Imperfection’ are also discussed for partition curve that helps in evaluating the effectiveness of various beneficiation equipment used for the upgradation of quality of coal received from different coal mines. It was observed that there is a tendency for the partition curves to steepen as the density of separation decreases. In other words, separations at lower density is sharper than separations at higher density.
Tensions of Transnationalism: Youth Rebellion, State Backlash, and 1968 in Poland
Authors: Fidelis Malgorzata
Published: August 2020

This article looks at Polish students who attempted to challenge the communist state’s hegemony with their own alternative interpretation of leftist politics during the pivotal era of the global sixties. This challenge culminated in student and youth demonstrations in March 1968 and the state’s violent reaction. In contrast to dominant narratives that depict 1968 in Poland and Eastern Europe as primarily shaped by the domestic political context, this article shows Polish students not simply as protesters against a “totalitarian” regime, but as active participants in a contemporary global search for a new kind of leftism. This quest involved turning away from the state as a potential vehicle for a socialist transformation, reformulating ideas of justice and solidarity, and engaging in leftist conversations across borders. The concept of transnational imagination is central to this discussion as both the young people and the state projected different visions of transnational solidarities and were influenced by crises happening elsewhere, including the Vietnam War and the Six-Day War in the Middle East. In Poland, the communist regime deployed and weaponized the transnational imagination against the protesters by launching a powerful antisemitic campaign. Stigmatizing protesters as Zionists and foreign agents alien to the Polish national community, the campaign solidified the racialized understanding of the “Polish nation,” which had lasting political consequences, including the shape of oppositional politics in the 1970s and 1980s.
Invited Commentary: Epidemiologic Methods as Applied to Epidemiology Education—Goals and Expectations to Advance and Diversify the Field
Authors: D’Agostino Emily M
Published: August 2020

In their accompanying article, Brown and Cox (Am J Epidemiol. 2021;190(2):305–312) offer strategies for improving introductory epidemiology instruction in large undergraduate classes using a team-based instructional approach. Effective epidemiology instruction can increase the quality and effectiveness of teaching and learning in our discipline. Recent work has suggested that epidemiology education can also be targeted as a mechanism to fuel equity and progress in the field. In this commentary, I contextualize Brown and Cox’s article within the literature on epidemiology instruction for undergraduates. I also explore the status of methods for measuring teaching and learning effectiveness in our field. I revisit what makes epidemiology a unique science and connect this with instructional strategies that have the potential to capitalize on these features. Lastly, I consider whether our field can improve in developing methods of measuring the effectiveness of epidemiology instruction for achieving these aims. Ultimately, as I suggest, increasing the rigor of methods for evaluating epidemiology instruction will serve to diversify, enhance, and advance our discipline.
Scanning window analysis of non-coding regions within normal-tumor whole-genome sequence samples
Authors: Torcivia J P , Mazumder R
Published: August 2020

Genomics has benefited from an explosion in affordable high-throughput technology for whole-genome sequencing. The regulatory and functional aspects in non-coding regions may be an important contributor to oncogenesis. Whole-genome tumor-normal paired alignments were used to examine the non-coding regions in five cancer types and two races. Both a sliding window and a binning strategy were introduced to uncover areas of higher than expected variation for additional study. We show that the majority of cancer associated mutations in 154 whole-genome sequences covering breast invasive carcinoma, colon adenocarcinoma, kidney renal papillary cell carcinoma, lung adenocarcinoma and uterine corpus endometrial carcinoma cancers and two races are found outside of the coding region (4 432 885 in non-gene regions versus 1 412 731 in gene regions). A pan-cancer analysis found significantly mutated windows (292 to 3881 in count) demonstrating that there are significant numbers of large mutated regions in the non-coding genome. The 59 significantly mutated windows were found in all studied races and cancers. These offer 16 regions ripe for additional study within 12 different chromosomes—2, 4, 5, 7, 10, 11, 16, 18, 20, 21 and X. Many of these regions were found in centromeric locations. The X chromosome had the largest set of universal windows that cluster almost exclusively in Xq11.1—an area linked to chromosomal instability and oncogenesis. Large consecutive clusters (super windows) were found (19 to 114 in count) providing further evidence that large mutated regions in the genome are influencing cancer development. We show remarkable similarity in highly mutated non-coding regions across both cancer and race.
Spatial density of open chromatin: an effective metric for the functional characterization of topologically associated domains
Authors: Jiang Shuai , Li Hao , Hong Hao , Du Guifang , Huang Xin , Sun Yu , Wang Junting , Tao Huan , Xu Kang , Li Cheng , Chen Yang , Chen Hebing , Bo Xiaochen
Published: August 2020

Topologically associated domains (TADs) are spatial and functional units of metazoan chromatin structure. Interpretation of the interplay between regulatory factors and chromatin structure within TADs is crucial to understand the spatial and temporal regulation of gene expression. However, a computational metric for the sensitive characterization of TAD regulatory landscape is lacking. Here, we present the spatial density of open chromatin (SDOC) metric as a quantitative measurement of intra-TAD chromatin state and structure. SDOC sensitively reflects epigenetic properties and gene transcriptional activity in TADs. During mouse T-cell development, we found that TADs with decreased SDOC are enriched in repressed developmental genes, and the joint effect of SDOC-decreasing and TAD clustering corresponds to the highest level of gene repression. In addition, we revealed a pervasive preference for TADs with similar SDOC to interact with each other, which may reflect the principle of chromatin organization.