The paper presents a finite element model of a reinforced concrete viaduct column retrofitted with a steel jacket. The model was developed in ANSYS software, accounting for material nonlinearity and contact interactions between the concrete column and the steel jacket. The selection of finite element types, material constitutive laws, and the friction coefficient is justified. Numerical simulations revealed three distinct stages in the composite behavior of the column–jacket system under loading. Particular attention was given to the analysis of the contact interface and the investigation of the steel–concrete friction coefficient, which significantly influences the system response at each loading stage and serves as the basis for distinguishing these stages. The study demonstrates that accounting for the composite action between the reinforced concrete column and the steel jacket yields an additional load-carrying capacity reserve of up to 16% compared to separate, non-composite design calculations. Furthermore, the paper includes an analysis of the influence of the spacing of transverse tie plates of the jacket on the load-carrying capacity of the retrofitted column and identifies optimal ranges for this spacing.

Keywords: material nonlinearity, stress–strain relationship или Constitutive law, steel jacket, Pipe rack column, coefficient of friction, strengthening, finite element model, reinforced concrete, composite action, nonlinear stress–strain model

The problem of the ultimate external pressure on a thick-walled concrete pipe internally reinforced with a metal pipe is considered. The pipe material is assumed to be ductile, not hardening under small deformations. The problem is solved under the assumption of plane strain. The stress state in the concrete mass and along the contact surface between the metal pipe and the concrete is investigated, assuming the concrete is in the ultimate limit state. A law for the change in the stress state in the concrete mass and a transcendental equation for determining the ultimate pressure on the outer surface of the concrete shell are derived. The ultimate uniformly distributed load acting on the outer surface of the concrete shell, within which the metal pipe is placed, is determined.

Keywords: concrete deformability, strength criterion, ultimate limit state, stress state in the concrete mass, ultimate pressure

The relevance of the study is due to the fact that: firstly, the proposed topic is in line with the Government-approved "Strategy for the development of the construction industry and Housing and Communal Services of the Russian Federation for the period up to 2030 with a forecast up to 2035" dated October 31, 2022, which assumes an increase in the share of industrial housing construction, including panel construction; secondlySecondly, the existing methods for calculating the joints of panel buildings have come down to us almost unchanged from the level of development of construction science and engineering in the 1980s. of the last century, which leads to increased material costs and rising real estate prices, therefore, the current trend in the development of the construction industry requires the improvement of these techniques. Modern approaches to nonlinear modeling and calculation of reinforced concrete will allow, in relation to panel joints, to reveal the reserves of their bearing capacity and obtain a more rational design, which will reduce the cost of constructing the buildings in question as a whole. PURPOSE. To carry out a comparative analysis of existing methods for calculating panel joints in two groups of limit states, to identify their advantages and disadvantages. Identify ways to improve them. METHODS used in the course of the research: theoretical methods – chronological, formalization, classification, analysis, synthesis, generalization, comparison. RESULTS. The analysis of existing methods of foreign and domestic design standards, as well as various author's methods, showed that: 1) foreign and domestic standards are based on the limit state method; 2) the nonlinear deformation model is not used in the calculation of joints of reinforced concrete panels; 3) to obtain a more accurate VAT of reinforced concrete panel joints, it is necessary to process a large amount of data using computer technology. CONCLUSION. The analysis shows that the use of computer software systems is the most promising method for calculating building structures, allowing fast and accurate calculations, reducing the cost of construction.

Keywords: large-panel construction, reinforced concrete, panel joint, joint calculation, joint classification, platform joint, deformation model, limiting forces, computer modeling, finite element

The paper considers the effect of particle size on the dynamics of suspended sediments in a riverbed. The EcoGIS-Simulation computing complex is used to simulate the joint dynamics of surface waters and sediments in the Volga River model below the Volga hydroelectric dam. The most important factor in the variability of the riverbed is the spring releases of water from the Volgograd reservoir, when water consumption increases fivefold. Some integral and local characteristics of the riverbed are calculated depending on the particle size coefficient.

Keywords: suspended sediment, soil particle size, sediment dynamics, diffusion, bottom sediments, channel morphology, relief, particle gravitational settling velocity, EcoGIS-Simulation software and hardware complex, Wexler formula, water flow

The aim of this work is to determine the physico-mechanical properties of modified wood (pine) to study the possibility of its use in parquet flooring.
The proposed modification method involves heating the wood using microwave technology and pressing it into a square cross-section. The density of pine increases significantly with the proposed technology and exceeds that of oak. The static hardness of the modified pine falls into the category of hardwoods. The core part of the sample is pressed more densely and belongs to the category of very hardwoods.
The compressive strength of the wood along the grain is 4 to 6 times greater than its strength across the grain. Therefore, from the perspective of compressive loads, parquet elements in the form of end-grain blocks are preferable. The compressive strength along the grain of the modified wood is practically equal to that of oak. The shear strength is probably the most vulnerable and, consequently, the most important strength characteristic for the proposed type of parquet; it is 10–13 MPa, compared to 6–12 MPa for common wood species.
Shrinkage and swelling of wood occur due to the removal of bound moisture from the cell walls; that is, if the wood's moisture content falls below the fiber saturation point, shrinkage reaches its maximum value. The proposed wood modification method (microwave technology) helps to avoid structural distortions associated with shrinkage. When wood is moistened up to its fiber saturation point, the wood cell walls thicken and swell, leading to an increase in the dimensions and volume of wooden products. The conducted experiments on the kinetics of swelling show that the modified wood is highly sensitive to changes in ambient humidity, which will undoubtedly lead to warping of the parquet. Therefore, this material can be recommended for use only on the condition that a completely waterproof coating is applied to the surface of the product. The thickness of the lacquer film should be at least 60 microns, and the quality of the lacquer coating should be no lower than class 3.

Keywords: wood, modified wood, determination of wood properties, mechanical properties of wood, influence of moisture on wood properties, wood swelling, parquet

The characteristics of a submersible induction motor are described with sufficient reliability for practice by the theory of multi-motor electric drive. In this case, the classical circuit of a submersible induction motor is a coupled system of several equivalent-T circuits. In turn, this significantly increases its computational complexity and reduces the speed of ACS. It is proposed to construct a mathematical model of the submersible electric motor in the form of polynomials with significantly higher speed using the methods of experiment planning. In the area of applicability, the differences in the estimation of energy performance do not exceed 1.1%, between the proposed models and classical equivalent-T circuits.

Keywords: automated control system, mathematical model, polynomial, mean absolute percentage error, computational complexity, design of experiment, scatter diagram, modal interval, submersible electrical motor, rotor package

This study presents a method for preprocessing data sequences aimed at identifying and grouping different data files for subsequent use in training neural networks. An algorithm for file comparison based on the relative deviation of feature values ​​is proposed, taking into account boundary cases (zero and near-zero values). The implementation includes parallel processing to improve performance and the generation of detailed reports. The method is tested on a dataset containing 10,000 files with parameters of a chemical process in a laboratory reactor. The results demonstrate the method's effectiveness in identifying stationary regions and generating balanced training sets.

Keywords: вata preprocessing, relative deviation, machine learning, parallel computing, file grouping, computational fluid dynamics, chemical reactor

Ring-shaped reinforced concrete structures are widely used in construction. For example, in the form of underground pipelines. They experience a complex nonlinear deformed state (VAT), which is analytically described as a complex mathematical problem of mechanics. Therefore, numerical methods are often used to solve it. This article uses the finite element method (FEM) implemented in the Lira-CAD 2022 PC. The VAT of reinforced concrete pipelines is determined in a physically nonlinear formulation, taking into account 4 factors of influence: the inner diameter, the concrete class, the properties of the filling soil, and the properties of the foundation soil. A plan has been drawn up for a complete multifactorial numerical experiment, which includes 81 models. The values of internal force factors in all sections of the underground pipeline are obtained, taking into account the variation of each factor individually and taking into account their mutual influence. Combinations of factors giving extreme values of internal forces in the pipeline have been established. Based on this, recommendations for rational design have been developed.

Keywords: underground pipeline, reinforced concrete, computer modeling, longitudinal profile, cross section, PC "Lira-CAD"

The paper is devoted to problems that arise in practical classes when solving physics tasks for students of engineering majors at the university. Examples of classification of tasks by types are given, taking into account certain criteria. Factors that contribute to the development of students' skills in solving physics tasks are considered. Solutions to the above-mentioned taskss are briefly discussed. A diagram is proposed that shows the main stages of solving a quantitative physics task, as well as feedbacks that seem essential in the course of the solution.

Keywords: physics, engineering direction, practical lesson, task, solution, main stages, problem during solution, mathematical training, mastering the discipline, element of creativity, methodical instructions

The article considers the assessment of the suitability of solar radiation data from ERA5 atmospheric reanalysis for forecasting problems in the northern territories. The experimental site of the Mukhrino station (Khanty-Mansiysk Autonomous Okrug), equipped with an autonomous power supply system, was chosen as the object of analysis. A statistical analysis of the annual array of global horizontal insolation data obtained using the PVGIS platform has been carried out. Seasonal and diurnal features of changes in insolation are considered, distribution profiles are constructed, and emissions are estimated using the interquartile range method. It is established that the data are characterized by high variability and the presence of a large number of zero values due to polar nights and weather conditions. The identified features must be taken into account when building short-term forecasting models. The conclusion is made about the acceptable quality of ERA5 data for use in forecasting energy generation and consumption in heating systems.

Keywords: ERA5, solar radiation, horizontal insolation, the Far North, statistical analysis, forecasting, emissions analysis, renewable energy sources, energy supply to remote areas, time series, intelligent generation management

An inter-turn short circuit (ITSC) in a power transformer winding is a primary cause of transformer failure. Existing methods for ITSC identification have limitations when applied in field conditions. To address this issue, a mobile hardware–software system for identifying electrical equipment parameters (PAK IP-10) has been developed, based on analyzing the decay of a direct current pulse. Verification of the test results for reproducibility, using Cochran’s criterion, demonstrated that the developed PAK IP-10 can be recommended for identifying the presence or absence of inter-turn short circuits in transformer windings.

Keywords: power transformer, inter-turn short circuit, identification, direct current decay test, Cochran’s criterion

The application of electric energy storage systems in the electric power industry of the Russian Federation is considered using the example of the Irkutsk Region and the Zabaikalsky Krai. Statistical data are provided, and an analysis is conducted for the specified objects of the electric power complex. The results of calculating the economic efficiency of implementing energy storage systems are presented

Keywords: electric power grids, renewable energy sources, energy storage systems, power supply

The development, implementation and continuous improvement of diagnostic systems for Russian Railways (RZD) infrastructure facilities are defined as conditions for ensuring reliable and safe operation. The current concept regulates the stages and directions of development of diagnostic systems for the period up to 2030, with a development perspective up to 2035. It is planned to create integrated, stationary and mobile monitoring and diagnostic systems.
The most optimal, from the point of view of the effectiveness of the diagnostic system, is to provide the ability to monitor diagnostic parameters with a given accuracy, automatically, without disabling equipment, in real time. This approach significantly simplifies operational control procedures. There is no need to change the condition of the equipment and power supply circuits. The number of personnel involved in carrying out diagnostic procedures is decreasing, as well as the influence of the human factor on the results is decreasing. The article discusses ways to automate the isolation control of Russian Railways infrastructure facilities.

Keywords: diagnostic system, infrastructure, operational control, automation

The paper examines the causes of the decline in the quality of electrical energy in small settlements. A linear multiplicative model for forecasting electrical loads has been developed based on a time series of electricity consumption in one of the small settlements. A posteriori verification of the multiplicative model has been performed, and the efficiency of the developed model for medium-term forecasting tasks has been demonstrated.

Keywords: electricity consumption, small settlement, linear regression model, multiplicative model, forecasting electrical loads, quality of electrical energy

The construction of a mathematical model for solving the problem of planning construction excavation, which is interpreted as a problem with a linear objective function and constraints, is considered. The calculation algorithm is implemented by software in Python using the scipy.optimize.linprog library, which provides effective methods for solving linear programming problems. The developed program visualizes the results, making the allocation of time for the operation of machines. When testing the program, scenarios with different input data were considered, allowing us to conclude that the developed tool helps to make the best decision when planning construction work and analyze the impact of changes in input parameters on the result.

Keywords: organization of construction, linear programming, distribution tasks, optimization, planning, mathematical modeling, simplex method