This PDF file contains the front matter associated with SPIE Proceedings Volume 12986, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

A 2-D exoskeleton model with five variable-length links is proposed in the article. The model features not only the active control in the hinges joining separate links, but also the controlled link length alteration. The controlled alteration of the angles between the links in this model is implemented by the drives with reduction gears. The electric drives with rack and pinion gears control the change of the link lengths. Thus, all the degrees of freedom describing the 2-D exoskeleton model are controlled. The electric drives can implement various control algorithms. The method of programmed motion control by specifying information about alteration of kinematic properties describing it is used in this article. Based on this information and the system of differential equations of motion, which is solved algebraically for the control torques and lengthwise forces, their analytical expressions are derived. Thus, the inverse dynamics problem is solved. On the basis of the found control actions, the electric drives have been selected. Electric motors, reduction gears, and rack and pinion gears have been selected from the list of the currently manufactured standard products.

The exoskeleton comfortability issues are not solved at present, which prevents their widespread application. The study suggests a method of resolving these issues based on the variable-length links with adjustable stiffness. The paper describes the 3-D model of exoskeleton supporting leg consisting of two variable-length links with adjustable stiffness. The payload is simulated with a point mass located at the end of the second link. The link length control is implemented by adjusting the stiffness of magneto-rheological fluid in the links. The fluid stiffness depends on the applied magnetic field strength. The pivoting points are simulated with spherical hinges. The system dynamics is described by the Lagrange equations using the angles between neighbouring links and the coordinate corresponding to the link length. Inverse dynamics problem solution methods for systems with constraints stabilization are used for obtaining control torques and lengthwise forces. The animation of mechanism motion demonstrates the adequacy of the proposed simulation procedure. The proposed model can contribute to development of more comfortable exoskeletons that are simulating biomechanics of human musculoskeletal system more precisely.

For small-scale and single production, FDM printing is considered as a technology competing with the well-known method – injection molding. However, due to the specifics of the printing process associated with layer-by-layer formation printed parts are significantly inferior to parts obtained by injection molding in terms of strength and surface quality, minimizing the advantages of 3D-printing. The methods that make it possible to improve the physical and mechanical characteristics of a printed parts include bulk treatment methods based on thermal effects on the whole part. The aim of this paper is to compare the technologies of bulk thermal post-processing in terms of the effect on the physical and mechanical properties of FDM-printed samples. Three methods of bulk thermal post-treatment are considered: annealing in a dispersed environment, annealing in a dispersed environment with pressure, annealing in a vacuum bag. The properties and deformations of ABS plastic samples printed by the FDM-method are investigated. The research results showed that all the considered technologies of bulk post-treatment of FDM-printed samples can be considered promising to improving physical and mechanical properties. The best results of minimizing deformations after annealing are observed after treatment in a dispersed environment consisting of gypsum powder. The obtained unsatisfactory results of changing the sizes of samples annealing in a vacuum bag may be related to the imperfection of this post-treatment method.

The article formulated a hypothesis about the existence of particles with negative mass. The main purpose of the work is to study and substantiate this hypothesis. The procedure and research methods are based on the generalization of some experimental data and the simplest theoretical relationships. The results of this study suggest the existence of an alternative mechanism for the accelerated expansion of the Universe. This is due to two factors. Accumulations of particles with negative mass have a repulsive potential (antigravity potential). These clusters are responsible for the expansion of the universe. The accelerated expansion is associated with the acceleration of time near objects with negative mass (the antigravitational twin paradox). The conducted research allowed revealing one more interpretation of the fine structure constant, expanding its physical meaning. So the force of gravitational interaction of two charged maximons is 1/α time greater than the Coulomb force. We can assume the existence of two components of dark matter. One of them consists of particles and antiparticles with negative mass.

The article discusses the possibility of implementing a time loop for microcosm objects. This is a direct consequence of the identity of the particles. The authors study the phenomena of charge exchange of fast nucleons during their collision (transition of a neutron into a proton, a proton into a neutron). A thought experiment is proposed. When a neutron that has decayed into a proton collides at high speed with another neutron, a nuclear charge exchange reaction occurs. As a result, the proton becomes a neutron again. Thus, his future is identical to the past. If the quantum numbers of two particles (for example, neutrons) coincide, then these particles are considered identical. Similar phenomena occur within atomic nuclei, where protons and neutrons constantly (virtually) transform into each other. As a result, the lifetime of a nucleus for an external observer can be thousands of years, and for nucleons, due to periodic time reversal, it can be on the order of 10^–22 s (time loop cycle).

In most cases, decays of a neutral π-meson are realized due to electromagnetic interaction. However, some rare decay modes can only be explained by weak interactions. We can assume that the decays are realized due to the electroweak interaction. Weak interaction is virtual in the decays π⁰ → 2Υ; π⁰ → Υ + e⁺ + e^–. Electrically charged particles and antiparticles born in weak virtual decays are annihilated due to electromagnetic interaction. During decays through other channels, weak interaction is real, and electromagnetic interaction has practically no effect on the decay processes. This is confirmed by the relatively long average lifetime of a neutral π meson during rare decays.

The design of a miniature eddy current transducer has been developed and improved, a hardware and software complex has been constructed, and methods for testing thin metal films have been presented. The results of measurements using the developed eddy current transducer operating under the control of a hardware and software complex are presented. The possibility of using the developed system to study the thickness of thin metal films is demonstrated. The dependences of the amplitude of the output signal of the ETC on the frequency of the exciting signal when scanning a thin copper film were obtained. A dependence has been compiled demonstrating the relationship between film thickness and electrical conductivity.

The article provides a review of the current state of the art of using mold sleeves in continuous casting machines. It is shown that continuous casting technology continues to actively develop. The target requirements that mold sleeves must provide include thermal conductivity and heat and wear resistance. The main achievements in the field of increasing thermal conductivity and heat and wear resistance are analyzed. It is shown that many of the methods used are already exhausted, and new approaches are required based on the study of deep properties, in particular the structural and lattice thermal conductivity of copper. As a first step, their calculations and modeling can be carried out.

Auxins are important class of bioactive compounds, regulating plant growth. They are used as herbicides and components of nutrient mixtures for microclonal propagation. There are many suggested synthetic compounds with auxin-like activity; one of the most widely-applied is phenoxyacetic acids. Usually they are based on halogenated phenols, but alkylphenols are much less known for these purposes. In this work, we have estimated the basic properties of alkylphenoxyacetic acids by quantum-chemical calculations with DFT B3LYP method. We considered several acids based on dimethyl-, trimethyl-, tert-butyl- chlorinated phenols, chlorinated thymol and carvacrol with comparison to commercial available herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) and revealed that (4-chloro-3,5- dimethylphenoxy)acetic acid is the most promising compound with optimal characteristics for possessing auxin-like activity.

Magnetorheological elastomers are among the most attractive smart materials for use in vibration protection because their mechanical and viscoelastic properties can be reversibly, precisely and quickly tuned using an external magnetic field. In these materials, magnetic particles are located in a polymer matrix, so the particles do not settle over time. The main difficulty in obtaining magnetorheological elastomers is the uneven distribution of magnetic particles in the volume of the polymer at the polymerization stage. A setup for synthesis with a uniform distribution of magnetic particles is presented, including a reactor, a solenoid, and an external adjustable voltage source. Loading graphs for the synthesized elastomers are presented. The loading of two elastomer samples with and without pores is assessed.

The efficiency of fiber impregnation with a polymer melt is one of the most important components that make up the quality of the UD-prepregs and, subsequently, parts made of them. If thoroughly formulated, the mathematical impregnation model could assist to find the most suitable parameters to enhance the impregnation. Consequently, the investigation of the fiber bundle impregnation with the high-viscosity thermoplastic resin melt by pultrusion with impregnation die is represented. An approximate one-dimensional mathematical model of roving impregnation during pultrusion through an impregnation die which considers the polymer melt leakage into fiber bundle is established. The maximum total impregnation depth of fiber bundle depending on the various values of the pulling speed and the fiber tension is calculated. The results show that the calculations of the impregnation depth are hinge on the leakage consideration, as well as on pulling speed and tension.

In the present work, small oscillations of a rectilinear edge dislocation in a nondissipative crystal are studied. An expression is written for inverse generalized susceptibility of edge dislocation, which takes into account influence of the Peierls relief and elastic interaction with a chain of point defects. It is shown that at, a rectilinear edge dislocation can have only quasi-local oscillations. Expression is found for internal friction due to emission of elastic waves by a oscillating edge dislocation. As an example, oscillations of edge dislocation in aluminum crystal with point defects of "substitution atom" type are considered. Frequencies of quasi-local oscillations of the edge dislocation are calculated and plots of frequency dependence for internal friction are plotted.

In this work, an expression is found for generalized susceptibility of an infinite edge dislocation in a real crystal. Effect of the Peierls relief and elastic interaction between the edge dislocation and chain of point defects are taken into account. Small bending vibrations of the edge dislocation in the Peierls valley are considered. An expression is found for internal friction caused by radiation friction of the edge dislocation bending vibrations. As an example, bending vibrations of the edge dislocation in an aluminum crystal with point defects of "substitution atom" type are considered. Graphs of internal friction frequency dependence are plotted for two possible cases of elastic wave emission by the vibrating edge dislocation.

Information is given on the application of the acoustic emission method for studying the kinetics of destruction of protective and decorative coatings of cement concrete. A different nature of the destruction of coatings has been established. When evaluating the nature of the destruction, it was found that for coatings based on polymer-lime paints, after curing, an adhesive type of destruction is characteristic, while for PVAC coatings it is cohesive. Thermal aging mainly changes the nature of destruction of PVAC coatings from cohesive to adhesive. With a decrease in the porosity of the substrate, higher values of the energy released when the coatings are detached from the substrates are observed.

In this work, a chalcone obtained from acetylcoumarin and vanillin was used as a starting compound for the synthesis of new effective antioxidants. A preparative method has been developed for the preparation of pyrazole and pyridine derivatives by the reaction of chalcone with hydrazine hydrate and malonodinitrile; the product yields were 29 and 61%. The synthesized substances were characterized by IR spectrometry, mass spectrometry and NMR spectroscopy. The antioxidant ability of the obtained substances was studied in comparison with 4-methyl-2,6-di-tert-butylphenol, including Fe-reducing ability and antiradical activity. The resulting compounds in both methods showed better results compared to the commercial antioxidant.

In this study 2 samples of polyalkenyl succinimide were prepared by reaction between diethylenetriamine and pentaethylenehexamine with alkenyl succinic anhydride with a C20-26 alkyl chain length. The influence of alkenyl succinimides on the aggregative stability of petroleum dispersed systems was studied. The ability of alkenyl succinimides to influence the processes of crystallization of paraffins in oil and gas condensate, as well as their ability to influence the processes of aggregation of petroleum asphaltenes, was analyzed. The resulting compounds did not affect the crystallization processes in oil, but showed a depressant effect in gas condensate, the depression of the pour point was 13 °C, which turned out to be better than the industrially used additive (DMN-2005), which did not show an effect. PEHA-based alkenylsuccinimide was able to inhibit the aggregation of asphaltenes, increasing the ONCET point by 1.5 times compared to the original asphaltenes.

The results of the study of the strength of slag-alkaline concrete depending on the amount of activator are presented. As an activator of slag-alkaline binders, the waste of caprolactam production of the Chirchik plant "Electrochemprom" was investigated. The best results were shown – ground granular phosphoric slags in a composition with an activator - sodium sulfocarbonate, which is recommended to be used to strengthen soils. The required strength class of soils can be obtained by adjusting the amount of slag, sulfocarbonate, as well as using various technological techniques.

The issues of analysis of the control loops of technological schemes of papermaking production for criticality are considered. The definition of the control loop's criticality is given. The classification of control loops by criticality is proposed. Examples of the most critical control loops are demonstrated. It is shown that the largest contribution to the error of the control loops is made by control valves. An algorithm for selecting control valves for critical control loops is proposed. The achievable indicators of the economic effect for the most critical loops for the technology are shown. The lines of loop's development depending on the trends of technology development are generalized. Taking into account the generalization of trends in the development of control loops, promising directions for the development of control valves are shown both as part of the measurement loops critical for the technology, and as part of the control loops common to the technology.

Introduction. From a geometric point of view, a water tower is a shell of rotation that has axial symmetry. For an axisymmetric system, it is possible to replace the spatial design scheme with a flat design scheme. This scheme can be used, among other things, under the action of arbitrary loads, such as wind loads and additional loads that arise when the structure tilts. Purpose of the study: Development and application of high-precision and cost-effective methods for analyzing the stress-strain state of combined axisymmetric systems using the example of a water tower. Research objectives: Development of mathematical models of asymmetrical loads, solution of practical problems arising during the installation and operation of water towers. Methods: orthogonal sweep method S.K. Godunov, Newton-Kantorovich method, finite element method, harmonic analysis, expansion of a function in Fourier series. Results: A method for analyzing the stress-strain state of combined systems using axisymmetric design schemes in the AXIS-Lq 2.1 program is considered using the example of a water tower. Mathematical models of wind loads and loads arising when a structure tilts are proposed, with the expansion of load functions in Fourier series. A dependence is proposed that approximates the graph of the aerodynamic coefficient. The Fourier coefficients for this dependence are found and the convergence of the trigonometric series is investigated. An example of using the AXIS-Lq 2.1 system for the finite element analysis of a Rozhnovsky water tower with a volume of 50 m³ is presented.

The article discusses the concept of projective differential geometry. It verifies the fulfillment of the condition of projective bending for a real gas in the convergence region of the virial decomposition. It is shown that thermodynamic surfaces corresponding to inert gases in the convergence region of the virial decomposition satisfy the conditions of projective bending. The resulting solution can be used for further analysis of the properties of thermodynamic systems using the apparatus of projective differential geometry.

The problem of utilisation of heavy oil by-products during oil refining is associated with high content of tarry asphaltene substances, coke, heavy metals and catalyst dust. A promising way to obtain commercial products from cube residues is low-temperature plasma chemical pyrolysis in liquid phase (NTP-plasma). The present work investigates the process characteristics of plasma-chemical pyrolysis of catalytic cracking residues (CCR) at current source voltages of 300- 700 V in order to optimise product composition and energy consumption. The gaseous NTP products of CCR pyrolysis contain (%mol): hydrogen (63.0-65.5), acetylene (21.8-23.6), methane (6.3-7.7), ethylene (2.7-3.4) and C3 - C6 hydrocarbons (1.9-3.7). Solid pyrolysis products are conglomerates of "sticky" particles of rounded shape in the size range from units to tens of microns. The maximum conversion of CCR pyrolysis was 78.9 % wt% at a minimum energy input of 3.3 kWh/kg at 500V.

The inhomogeneity of plastic deformation of laser cladding additively manufactured steel composites from low-carbon steel ASTM A414 grade A and stainless steel AISI 304 has been studied. The uniaxial tensile tests were carried out on flat samples with a thickness of 8 mm at a constant rate at room temperature after laser cladding and after six hours of heat treatment of specimens up to 900°C. The phase composition of the bimetal components was determined via X-ray diffraction. The effect of heat treatment conditions on the microhardness and plastic flow inhomogeneity near the bimetal junction zone has been established. The degree of plastic deformation inhomogeneity of different layers was quantitatively assessed using the coefficient of variation of local strains has been investigated via digital speckle correlation method. After laser cladding, the difference between the deformation inhomogeneities of the border zones near stainless and carbon steels was almost two times. The deformation inhomogeneity in the transition zone was shown to differ from those of the base layers, which affected the properties of bimetal products. The effect of structural heterogeneity near the interface of layers on the local strain distributions in the bimetal was discussed in present study.

This paper presents the results of laboratory research aimed at studying the behavior of suspended high-voltage insulators of overhead power lines under their uniform and non-uniform contamination. By continuously recording the values of the leakage currents as well as the signals coming from two types of remote sensors, characteristics are revealed which can be used as diagnostic signs. Characteristic of the discharge activity on the surface of lightly contaminated insulators under fog moistening is the sudden appearance and short duration of intense discharges.

The paper analyses the methods of evaluating the functioning of mining and transport equipment of mining enterprises. Formulas of leading scientists, which take into account the criteria of evaluation of functioning of mining and transport equipment for analysis of research in this field, are given. Dependences for determination of technical, operational productivity of excavators, dump trucks and crushing equipment, taking into account specific mining-geological, mining-technical, climatic, organisational and other conditions of equipment operation are offered. It gives an opportunity for planning and rationing of excavation-loading machines, selection and provision of transport and establishment of rational mode of their functioning. Functional criteria of theoretical, technical and operational functioning of mining and transport equipment of mining enterprises are established. In this regard, it is of interest to determine the value of the criteria for assessing the functioning of mining and transport equipment, taking into account the factors outlined.

The tension applied to the conveyor belt and rollers was determined based on mathematical calculations, and the distribution of the belt, side rollers and middle rollers was determined, as well as the changes in the length dimensions of the belt conveyor support rollers in the range of impact forces, the side roller inclination angles of the falling stresses in the range of 0-360, the length of the middle roller, the length of the side rollers, the belt the dependence of the width on the fullness coefficient was studied.

This article considers the issues of improving the mode of operation of fans of mines and mines. In mines these fans are driven by asynchronous and synchronous motors of high power and high voltage. These motors consume a lot of electricity. In order to reduce the power consumption, automation of these fans is an urgent issue today. With this in mind, a scheme and requirements for automatic control of the mode of operation of artificial lung ventilation devices using a microprocessor of the chief dispatcher based on signals from gas sensors have been developed.

The article explores the possibility of using microwave technologies for the thermal treatment of loess-like loams from the Chagan deposit in the West Kazakhstan region and converting them into building materials. The main goal is to assess the possibilities and prospects for using loess-like loams of the Chagan deposit in the West Kazakhstan region as raw materials for the production of ceramic materials. The article shows the microstructure of loess-like loam of the Chagan deposit at various magnifications and a derivatogram of the sample. The high efficiency of microwave drying of samples and its advantages over traditional thermal methods have been proven.

The article presents the results of an industrial experiment carried out in the form of a full-factorial experiment with two factors corresponding to the main parameters of the laser hardening mode of GCr15 bearing steel - temperature on the surface of the sample and processing speed. Based on the results of a full-factorial experiment, regression equations were obtained - the dependence of the depth and width of the laser impact zone, surface hardness on temperature and processing speed. Contour curves of the surface of equal response were also constructed and a search was made for the optimal parameters of the laser hardening mode, providing maximum values of the depth and width of the laser impact zone and surface hardness. It was found that the maximum values of these parameters are provided under the following laser hardening modes: temperature in the range of 1470–1500 °C, processing speed 5–10 mm/s.

The synthesis of the adduct of the Diels-Alder reaction between thiophene and maleic anhydride has been carried out in a barostat for 32 hours at a pressure of 8000 atmospheres and a temperature of 105 °C. The adduct yield was 25%. In repeated synthesis for 50 hours under the same conditions, the yield was 35%. The adduct has been obtained by recrystallization from diethyl ether. The crystals of this adduct have been grown for the first time. X-ray analysis revealed the formation of the exo-adduct.

This article investigates the photocatalytic bleaching of various dyes using pillared materials as catalysts and ultraviolet light (280-320 nm). It has been determined that different dyes exhibit varying sensitivity to oxidation, likely due to their chemical structures. The methylene blue (MB) dye undergoes significant changes after prolonged exposure to UV light, while the Congo red (CR) dye demonstrates greater stability. The order of resistance to UV irradiation was determined through analysis of the dye spectra. Detailed examination of the dye degradation dynamics revealed that CR and MB are most sensitive to hydrogen peroxide oxidation in the system with pillared bentonites. The bleaching process is enhanced with an increasing catalyst concentration. Factors influencing the degree of dye degradation include the chemical structure, size, shape, and potential interaction with the surface of the pillared bentonite. Ultimately, pillared materials are emerging as promising catalysts for the photocatalytic bleaching of dyes in wastewater.

This article analyzes the power required to maintain the forced oscillations of a chevron-type supply cylinder. The energy required to maintain oscillation for one period of the proposed composite feed cylinder is discussed graphically and numerically. Wherever possible almost all proposed boundary parameters are given in tabular form.

The article provides a comparative analysis of the physical and mechanical characteristics of samples of chemicalthermomechanical mass (CTMM) after the first and second stages of grinding, as well as after drying the mass. It was found that increasing the drying temperature reduces the quality indicators of wood pulp. Based on research results, methods have been proposed to reduce the phenomenon of keratinization of fibers as a result of their drying. The possibility of using chemical-thermomechanical mass in the production of cardboard is also considered. For this purpose, compositions were made from waste paper and chemical-thermomechanical mass in various percentage ratios. Research has shown that even taking into account the deterioration in the strength characteristics of the finished product when adding chemical-thermomechanical mass, the resulting properties of the composition of chemical-thermomechanical mass and waste fiber allow the production of paper for corrugation close in quality to the highest grade B-0.

The article describes the technical problems that arise when modeling exoskeletons with variable length links and electromechanical drives:the delay of the executive mechanisms of the exoskeleton with increased movements of the human musculoskeletal system, which has a negative effect on the dynamics of the joint movement of a person inside the exoskeleton. The consequence is the lack of synchronization in the joint work of the human-exoskeleton cyborgic system. This reduces the comfort of using exoskeletons. An analysis of the prospects for improving the technologies for controlling electromechanical models of exoskeletons based on neuro-fuzzy networks is presented. The prospects for autonomization of exoskeleton control with the help of neural networks are determined. An analysis of possible problems associated with the introduction of intelligent control of the exoskeleton was carried out, solutions were proposed for the use of a neuro-fuzzy network to control the electromechanical model of the exoskeleton.

The influence of deformation and temperature on the value of the kinetic parameter—the activation energy of the plastic flow of glass-basalt plastic—was studied. The glass basalt plastic samples differed in the ratio of components in the binding compound. In the process of studying the thermal activation properties, it was shown that the activation energy of the plastic flow of a material is an indirect characteristic of thermal resistance, i.e. in a certain range of heating temperatures of the material at the same values of applied forces, a change in activation energy occurs as a consequence of structural changes in the binder. The purpose of this work was to determine the thermal activation parameters of glass basalt plastic based on epoxy resin, a curing compound - isomethyltetrahydrophthalic anhydride (IsoMTPHA) and a flexibilizer - carboxylate rubber SKN-26-1A. Studying the relationship between mechanical characteristics and physical properties of a substance is the basis for promising methods for predicting kinetic parameters in a wide temperature range. As a result of the study of creep kinetics, the following results were obtained: 1) the influence of the composition of the glass-basalt-plastic binder compound on the value of the initial activation energy of the plastic flow of the material has been established Q₀ in a wide range (2.68- 2.445 K) of loading temperatures was discovered; 2) a regression analysis method is proposed for statistical processing of the obtained Q₀ values. The use of the temperature jump method is advisable at any temperature where inelastic deformation is observed. The value of the activation energy of plastic flow correlates with the magnitude of internal stresses, the flow rate of the material, and can be a characteristic of the thermal resistance of the material.

During the extraction of gold-bearing ores in mines, the amount of air in the ventilation network of mines increases in proportion to the increase in the length of mine workings and the deepening of mines. The article discusses ways to regulate the air flow into the mine, prevent external and internal losses of air volume in the mine, reduce aerodynamic resistance, and in this case, the use of equipment and devices used for proper air distribution.

The article discusses three spatial models of exoskeletons: with four, five and n links. In accordance with the biomechanics of the human musculoskeletal system, the models use cylindrical, combinations of two cylindrical hinges with mutually perpendicular axes of rotation, and spherical hinges. The change in angles between the links is controlled using electric drives located in the hinge area. Unlike those considered earlier, in this model, a section of variable length is assumed to be significant, and the drive that controls the change in the length of the link is located in this section. The models provide for the presence of a battery attached to the hip joint, simulated by a concentrated mass. In addition, the five-link model includes auxiliary elements that support the user's head in the form of a point mass. As a simplifying assumption, it is assumed that the entire mass of a section of variable length is concentrated in its middle. A drive that changes the length of a link can be implemented in the form of a rack or pinion gear with an electric motor. Using the method of software motion control, for the considered models with 4 and 5 links, the inverse problem of dynamics was solved and the influence of the body on the forces developed in the lower extremities of the exoskeleton was analyzed. The significant impact of adding a body on exoskeleton control has been established. Based on the analysis of the obtained systems of differential equations of motion, a generalization of the exoskeleton model to the case of an arbitrary finite number of links is proposed.

Thermodynamic simulation of the reduction of cerium from slag system of the CaO-SiO₂-Ce₂O₃-Al₂O₃-MgO at temperatures of 1550 and 1650°C was performed using the HSC 6.1 Chemistry software package (Outokumpu) jointly by the method of planning a simplex lattice experiment. The results of mathematical modeling were presented graphically in the form of “composition–equilibrium content of cerium in the metal” diagrams. During the exposure of steel (0.17% carbon, 0.47% silicon and 0.05% aluminum) under cerium-containing slag, from 0.39 to 27.93 g/t of cerium passes into steel, depending on the temperature of the metal, the basicity of the slag and cerium oxide content. The process of cerium recovery is positively affected by increases in the process temperature, slag basicity and cerium oxide content. Experimental studies have shown direct microalloying of steel with cerium from slags containing cerium oxide due to the reduction of its reduction. It is shown that up to 20 ppm of cerium passes into steel, kept under slag with 7% Ce₂O₃, basicity 5, in 10 min.

The article is a description and analysis of an experiment aimed at creating a high-quality magnetorheological fluid - a unique material capable of changing its rheological properties under the influence of a magnetic field. An experimental procedure is proposed that describes the detailed steps for creating such a liquid. The properties of the resulting magnetic rheological fluid were studied and its main problems were identified. The influence of some parameters, such as particle sizes and their stabilization, on the quality of the resulting liquid was assessed. Methods for determining its viscosity are described. The results of the study can be of great practical importance for the development of innovative solutions in the field of mechatronic systems, in particular for the creation of exoskeletons with links of variable length with adjustable rigidity.

A study of a high-frequency power source for induction heating was carried out. Using three-dimensional computer simulation in the ANSYS program, the design, electromagnetic and thermal processes of an electric machine high-frequency power source based on a high-speed electric synchronous generator with permanent magnets operating as part of a gas turbine unit were studied. A method has been developed for studying processes in high-frequency induction installations with an additional conducting medium (“cold crucible”, concentrator), that allows the analytical calculation of the main integral parameters of inductors in such installations (for example, calculation of the required supply voltage). The results of analytical calculations of the required voltage of inductor with a concentrator are presented.

This work is devoted to the issue of ash and slag waste disposal on the territory of the Russian Federation. In Russia, there are up to 1.8 billion tons of accumulated coal waste. They are buried in landfills and harm the environment and humans. The direction for the development of inorganic binders based on industrial waste with low energy consumption and low CO₂ emissions is actively developing. The purpose of this work is to study the process of geopolymerization of industrial waste from the fuel and metallurgical industries. The possibility of activating the structure formation of mixtures based on slag and ash components and the influence of activation parameters on the operational characteristics of the synthesized geopolymer stone are considered. Comprehensive indicators of geopolymer mixtures of different compositions, as well as an artificial composite based on them, have been obtained: normal density, setting time, average density, compressive strength and stretching in bending of a geopolymer stone. The influence of the density of an alkaline activator on the complex characteristics of a geopolymer material has been studied.

This review is devoted to modern methods of storing and transporting hydrogen in gaseous and liquid forms. The hydrogen storage and transportation system operates under unfavorable conditions: it experiences loads, high pressure, cryogenic temperatures, and exposure to hydrogen. Operation of equipment under conditions of simultaneous exposure to hydrogen and loads leads to stress cracking, which contributes to the initiation and development of cracks in hydrogen cylinders and valve elements. The article discusses the problems of the impact of hydrogen on structural materials during their storage and transportation. When choosing materials for equipment for storing and transporting hydrogen, an important aspect is to control the phenomenon of hydrogen embrittlement in order to ensure safe operation and longevity of the equipment.

Reinforced concrete compressed elements with a small eccentricity and methods for calculating their strength are considered. A method for determining the deformation of the longitudinal reinforcement furthest from the longitudinal force is proposed. At the same time, the use of a single formula for s is ensured during the transition from an alternating deformation plot to an unambiguous one. Empirical dependence is used to determine the height of the compressed zone, which avoids solving the quadratic equation. In elements with a small eccentricity, symmetrical reinforcement is used, for this case the equation of equilibrium of longitudinal forces is derived.

Test results from manufacturers of single screw pumps were studied. The expended power of a single-screw pump is directly proportional to the rotor speed. The proportionality coefficient represents the mechanical work of a single screw pump per revolution and increases linearly with increasing pressure drop. Energy efficiency and Specific energy consumption indicators were calculated for the Vulcan series single screw pump. Both indicators improve with increasing rotor speed: energy efficiency increases, specific energy consumption decreases. No maximum efficiency was found when the rotor speed changed in the studied range. If the frequency is fixed, then there is a maximum efficiency at a certain pressure drop. At higher pressure values, both indicators worsen. At lower pressure values, the energy efficiency indicator decreases, and the specific energy consumption indicator shows better energy efficiency. Therefore, when selecting single-screw pumps for operation under these conditions, the specific energy consumption indicator, and not the efficiency, should be taken into account.

The features of the interaction of highly dispersed expanded clay powder on the properties of bitumen binder have been studied. The nature and mechanism of physicochemical interactions at the interface between the mineral filler and bitumen phases have been revealed. It has been experimentally established that modification of bitumen with highly dispersed expanded clay powder has a positive effect on the segregation stability of crushed stone-mastic asphalt concrete mixtures.

Synthesized polyphenylene oxide asymmetric hollow fiber membranes with an outer diameter 500- 600 μm and an inner diameter 200 μm were investigated. The membrane wall structure asymmetry and the outer diffusion layer thickness were determined using atomic force microscopy. The results obtained are important for improving the performance of membrane selective gas separation and enrichment apparatuses for gas mixtures.