The paper presents an analysis of the methods for the chemical modification of biochar. The characteristics of acid and basic modifications, modifications with hydrogen peroxide, sulfonation, amination, impregnation with metal oxides, and magnetization are examined. It is demonstrated that the method of modification, the parameters of the technological process, and the nature of the modifying agent all exert an influence on the chemical composition, structure, porosity, pore size, and total specific surface area of the modified coal. The combination of methods, technological parameters, and modifiers allows for the production of sorbents for wastewater treatment based on biochar with specific properties for the sorption of certain groups of different pollutants.

Keywords: biochar, chemical modification, sorption properties, porosity, pore size

When evaluating student work, the analysis of written assignments, particularly the analysis of source code, becomes particularly relevant. This article discusses an approach for evaluating the dynamics of feature changes in students' source code. Various metrics of source code are analyzed and key metrics are identified, including quantitative metrics, program control flow complexity metrics, and the TIOBE quality indicator. A set of text data containing program source codes from a website dedicated to practical programming, was used to determine threshold values for each metric and categorize them. The obtained results were used to conduct an analysis of students' source code using a developed service that allows for the evaluation of work based on key features, the observation of dynamics in code indicators, and the understanding of a student's position within the group based on the obtained values.

Keywords: machine learning, text data analysis, program code analysis, digital footprint, data visualization

The work presents the review of modern log trucks under the recent sanctions imposed. The author states that the problem of renewing the existing log trucks becomes urgent for forest transporting and logging companies nowadays. There is a wide range of new basic chassis and trucks at the market to build log trucks with a wheel formula 6x4 and 6x6 produced by Russian, Belorussian and Chinese factories. A great number of trailer links is produced to build log trucks. There is an opportunity to buy used trucks of other companies. For the first stage of the technical and economic analysis and preliminary selection of the optimal type and composition of a logging truck, a comparative assessment of the effectiveness of logging trucks was carried out. The analysis shows that Russian log trucks with engine power more than 400 HP (horsepower) can compete with the best foreign models. Nevertheless, the problem of reliability of Russian, Belorussian and Chinese log trucks needs further research.

Keywords: log trucks, trailer links, productivity, effectiveness

The purpose of this work is to study the thermal stress of the furnace of a fire-tube boiler and its effect on the design of the boiler. To study the effect of thermal stress and furnace proportions on the ratio of heating surface areas, the calculated resistance was tested. Calculations of heat-tube boilers of sectional hot-water boilers with different proportions of the furnace at different thermal loads of the same furnace volume are performed. The calculation of each heating surface is carried out by the method of successive approximations, based in this case on the chord method. In the calculation process, the flue gas temperature at the outlet of the heating surface was first set, and then refined by successive approximations. To reduce the overall balance of the boiler, another global approximation is made when the temperature determined at the outlet of the last heating surface is set at the beginning of the calculation – in the heat balance, where it affects the loss with outgoing gases and the efficiency of the boiler. It is determined that the optimal.

Keywords: energy efficiency, fire-tube boiler, heat supply, thermal voltage, resource conservation

The condition of a vehicle sensor system is an effective indicator used by many other vehicle systems. This article is devoted to the problem of choosing a forecasting method for vehicle sensors. Sensor data are considered as multivariate time series. The aim of the study is to determine the best forecasting model for the type of data under consideration. The LSTM neural network-based method and the VARMA statistical method were chosen for the analysis. These methods are preferred because of their ability to process multivariate series with complex relationships, their flexibility, which allows them to be used for series of varying lengths in a wide variety of scenarios, and the high accuracy of their results in numerous applications. The data and plots of computational experiments are provided, enabling the determination of the preferred option for both single-step and multistep forecasting of multivariate time series, based on the values of error metrics and adaptability to rapid changes in data values.

Keywords: forecasting methods, forecast evaluation, LSTM, VARMA, time series, vehicle sensors system

The paper provides a brief overview of publications on the application of mathematical modeling methods in the study of the patterns of functioning of hydroelectric power plants (HPPs). In particular, the following are considered: mathematical models of the total minimum water consumption for a cascade hydropower system in China; a mathematical model of hydropower plants; a mathematical model of two small hydroelectric power plants operating in tandem; accurate modeling of hydraulic transient characteristics in a complex drainage system. The task of filling in the gaps in the data concerning the operation of hydroelectric power plants is formulated. The approach to its solution is proposed to be based on the use of the method described in previous publications by one of the authors and based on the use of regression analysis apparatus. The specific task of filling in data gaps for a hydroelectric unit of one of the Siberian hydroelectric power plants has been solved. The following factors are used: active and reactive power of the electric generator, voltage, current and temperature of the stator iron, rotor current, air cooler hot air temperature.

Keywords: hydroelectric power plant, electric generator, data gaps, predictive analytics, regression model, adequacy criteria

When operating gas distribution systems, the process of releasing various gases into the atmosphere is inevitable, negatively affecting the environment and creating a greenhouse effect. These gases can be either products of combustion of gaseous fuel or the result of natural gas leaks from gas pipelines and equipment. The main articles of gas leaks from gas pipelines and ways to minimize the negative impact on the environment are given.

Keywords: gas distribution system, greenhouse effect, gas combustion, methane, flanged and threaded connections, leaks, safety relief valve

The article considers the requirements of regulatory documents to ensure fire safety during construction and operation of gas distribution pipelines in Russia and China. The different approach to fire risk reduction in the two countries is revealed: more specific and stringent requirements in China and general requirements related to fire hazardous facilities in Russia.

Keywords: fire risks, fire regulations, natural gas combustion, causes of natural gas fires, natural gas transportation, fire safety

The article discusses the issues of modernization of the automated system for filling petroleum products (ASN). The complexity of maintenance of the automated control system due to the lack of up-to-date documentation and updated software, as well as periodic failures and high cost of spare parts became the main reasons for the implementation of modernization. Automatic control systems based on the law of proportional-integral-differential regulation have been developed: using a shut-off control valve with a positional actuator or a frequency converter to control the ACN. Mathematical models of the automatic control system have been developed in the MATLAB program using the Simulink library. An experimental model of a pumping station was assembled in laboratory conditions, and simulation modeling of the operation of an automated control system for a discharge and filling station was carried out. According to the results of experimental studies on the direct characteristics of assessing the quality of the transient process, the graph of a circuit with a frequency converter demonstrates the best results.

Keywords: automated pumping station, petroleum products, mathematical models, PID controller

Occupational safety is one of the important aspects of the organization of work in production. Domestic machines and units used in the food industry do not yet allow to exclude the impact of harmful and dangerous production factors, to make the work of employees safe. In this context, it is important to study active and passive methods of noise and vibration suppression, their effectiveness in ensuring normalized working conditions of workers on the example of a specific production. Existing research, as a rule, focuses on one criterion when choosing protection methods. However, an integrated approach is advisable in solving this problem. The purpose of this study was to choose a rational method of protecting personnel from the effects of noise and vibration based on the economic justification of effective technical solutions. The obtained research results make it possible to take into account the criteria for evaluating the validity and acceptability of choosing a particular protection method, including from the standpoint of technical and economic calculation, when designing a security system. The above study showed the expediency of import substitution in the food and beverage industry, as well as the correlation between the introduced protection systems and an increase in the level of safety. The given algorithm of the feasibility study has the properties of scale and generality. It can be successfully implemented when choosing methods of protection from the effects of other harmful production factors found in various industries.

Keywords: acoustic factor, protection methods, active and passive methods, economic justification, sound pressure levels, experimental data

Asphalt concrete mixes are the primary construction material for road surfaces, and precise design of their composition plays a key role in the quality and durability of road pavements. This article discusses the challenges associated with designing asphalt concrete mix compositions and presents a developed system for automatic mix selection. The automatic asphalt concrete mix composition selection system is a powerful tool for optimizing the material selection process used in road construction. This system can calculate the optimal mix composition, taking into account technical and economic constraints, leading to increased accuracy and reliability in mix selection. The advantages of this system include reducing the time and cost of the selection process, enabling testing and analysis of various mix options, ultimately improving the quality and durability of road pavements.

Keywords: asphalt concrete, asphalt concrete mix, composition selection, least squares method, linear programming method, software, automation, Python, Microsoft Access

The article presents a way to increase the load-bearing capacity of a reinforced concrete column due to metal clips from the corners with an increase in the load on it. To ensure the joint operation of the existing column and the metal cage, the corners are subjected to prestressing, which is achieved by compressing the corners with jacks.

Keywords: reinforced concrete column, column reinforcement, metal cage, prestressing of the cage

The article gives an insight into the traditional passive cooling techniques utilized in Mediterranean and hot climate regions, showcasing the effectiveness of natural ventilation and central patios in improving indoor thermal comfort and reducing energy consumption. The integration of these traditional design elements with modern technologies is crucial for creating environmentally friendly and culturally significant architectural solutions for the future. The discussion then transitions to the importance of energy efficiency and environmental sustainability in modern building design, highlighting the use of Ansys Fluent software for modeling natural ventilation in a residential apartment in Yemen. The article emphasizes the need for engineering and architectural solutions to achieve high performance in energy efficiency and environmental safety in contemporary construction practices.

Keywords: natural ventilation, Yemeni houses, Spalart-Allmaras model, civil engineering, Ansys Fluent

In order to negate the loss of strength, that can lead to collapse of constructions, we should take measures to prevent cracking. Every crack emersion in reinforced concrete indicates that the accumulated stress has been released in this area of the structure. The cause of cracks are internal tensile stresses that can occur due to internal processes in the element and from external loads on the structure. It is possible to eliminate cracks that have already appeared with the help of repair compounds that fill the volume of cracks in various ways. Injection, as one of the solutions, will help to maintain the strength and durability of the structure.

Keywords: cracking, concrete, reinforced concrete slab, crack, defect, deformation, strength, soil, repair compound, foundation, foundation slab, injection

The prospects for building a satellite Internet based on a low-orbit constellation of satellites (LOСS) are due to the fact that only it allows for stable and reliable communications anywhere on the planet. Therefore, the technology of satellite industrial Internet of things IIoT has become widespread in the oil and gas industry, many of whose facilities are located in the Far North. However, when using satellite low-orbit Internet (SLOEI), new threats and attacks arise against it. Among attacks on LOCS, a special place is occupied by attempts to impose unauthorized content on SLOEI subscribers. This situation can be prevented using a satellite identification system. For the effective operation of the “friend or foe” challenge-response system for LOCS, a copy-resistant authentication protocol with zero knowledge disclosure was developed. This property was achieved by reducing authentication time through the use of modular deduction class codes (MDCC). The use of parallel VDCC codes has led to a change in the method of satellite identification, which entails a revision of the principles for constructing a request-response system. Therefore, the development of a block diagram of a satellite identification system operating in the MDCC for a low-orbit satellite Internet system is relevant.

Keywords: imitation resistance, zero-knowledge authentication protocol, modular codes of residue classes, block diagram of the low-orbit satellite identification system