The study of contemporary development aspects of the urban environment in Russian historical cities is central to many research efforts dedicated to preserving the historical and cultural landscape. The primary goal of this research was to identify the development potential within the urban planning and spatial structure of central areas in historical cities, using Tula as a case study. The main challenges, principles, and optimal methods for reconstructing individual objects, areas, and the historically established planning structure of the city center were examined through the realized project of comprehensive area improvement and the creation of a modern public space, specifically the Kazanskaya Embankment, Metallistov Street, and Krestovozdvizhenskaya Square, adjacent to the Tula Kremlin. The research proposed an optimal strategic development solution for the historically formed urban environment: the reconstruction of selected cultural heritage objects and areas closed to public access, which had not previously been integrated into the city’s social and cultural life. The changes to the urban environment were identified at both the urban planning and architectural design levels and analyzed considering urban-ecological and economic factors.

The study analyzed the methods of hydraulic fracturing in horizontally oriented wells, along with techniques for strengthening soil foundations under existing building foundations using high-pressure injection (including those performed using sleeve grouting technology). The behavior of hydraulic fracturing in the soil mass was considered, which, in turn, also depends on the hydraulic fracturing pressure and the stress-strain state of the soil. A summary table was presented with formulas from domestic and foreign scientists for determining the pressure at which soil fracturing occurs. Based on the identified advantages and disadvantages of the considered soil foundation reinforcement methods, the authors proposed an alternative approach: strengthening the foundations using cementation during horizontally oriented excavation. The essence of the technology lies in the installation (using technologies that allow for trenchless horizontal drilling) of horizontal polyethylene (coiled tubing) pipes under or along the building foundation. Through these pipes, using sleeve grouting technology, a hardening solution will be injected into the soil under pressure equal to the soil fracturing pressure. This will create hydraulic fractures in the soil, thereby increasing its mechanical characteristics.

Air quality and microclimate parameters in classrooms impact student health and academic performance. Calculate the precise reduction in carbon dioxide concentration achieved through periodic ventilation is challenging. Therefore, an experimental study was conducted to evaluate the effect of ventilation on air quality and microclimate parameters during the cold season. The research object was a classroom with an area of 55.6 m2. On the first day of the study, ventilation was implemented before the start of classes and during breaks. On the second and third days, the ventilation schedule was determined by the students and lecturers. Carbon dioxide concentration, air temperature and relative humidity were measured using an air quality meter positioned in the center of the room at a height of 1.5 meters. On the first day, the air quality met the required standard for 16% of the teaching time, while it was acceptable and low for 47 and 37% of the time, respectively. The maximum carbon dioxide concentration reached 2639 ppm, and an unstable thermal environment was observed, with a maximum temperature increase of 4.7 °C over a 45-minute class period. Without control over the ventilation schedule and with the classroom door closed during classes, the duration of study time with poor air quality increased by 2.2 times, and the maximum carbon dioxide concentration was 1.3 times higher.

To estimate the fire resistance limit of reinforced concrete structures, it is essential to understand the temperature distribution within the concrete cross-section under standard fire conditions. Existing approximate analytical methods rely on the classical solution of the heat transfer equation assuming a constant surface temperature. The authors developed a degree approximation of the standard fire temperature curve. This approximation enables an approximate analytical solution to the heat transfer problem with a varying surface temperature corresponding to standard fire conditions. The aim of this work was to derive a convenient formula for heat transfer engineering calculations applicable to concrete with arbitrary thermophysical properties. The derived formula accurately predicts the temperature at any point within the concrete at a given time. The authors’ solution was compared with the high-precision numerical simulations (ANSYS, MATLAB) for various concrete types. Because the proposed approximation does not involve special functions, its implementation does not require any specialized software. The accuracy, simplicity, and versatility of this formula make it suitable for use in fire resistance engineering calculations to determine the time-dependent temperature distribution within concrete under standard fire conditions.

Decentralized Arctic settlements are equipped with modern water supply systems, yet they increasingly face the challenge of collecting and treating domestic wastewater. The study examined physical and chemical methods for treating domestic wastewater, similar in composition to wastewater from small northern settlements, with the goal of replacing the often inefficient biological treatment step, especially for organic substances. Wastewater samples at normal (18–22 °С) and extreme (3–6 °С) temperatures were treated in the laboratory using various technological schemes. As a result, the authors propose the most effective technological scheme for treating domestic wastewater in remote Arctic settlements, which includes the following stages: pre-aeration, sedimentation with coagulation and flocculation, chemical oxidation and struvite precipitation, and mechanical and sorption filtration. It was found that this technology is largely independent of water temperature and suitable for domestic wastewater with temperatures ranging from 3 to 22 °С. The implementation of this scheme reduced the concentration of ammonium ions by 96.5 %, suspended solids by 98 %, and chemical oxygen demand by 91 %. The proposed wastewater treatment scheme will simplify the operation of treatment plants in challenging Arctic conditions and enable their operation in automatic mode.

Textile reinforcement of concrete structures is promising trend in modern construction. These structures are lightweight, strong, stable, and require fewer materials. However, the use of textile-reinforced concrete in cantilever structures has not been previously studied. The authors designed and manufactured prototypes of lightweight textile-reinforced concrete cantilever coverings. The prototypes underwent strength testing in the laboratory. In addition, finite element modelling was performed to analyze the stress-stain state of the structures. Tre results showed that the maximum failure load of the prototype was 400 N, equivalent to a stress of 4.08 MPa, exceeding the strength of B20 class concrete by 1.9-2.4 times. The effectiveness of textile reinforcement was demonstrated under critical loading conditions, and the residual strength of the structure provided stability after the concrete matrix failure. The prototype could form the basis of commercial solutions. This technology is promising for use in regions with stringent structural reliability requirements, including seismically active zones.

This study examines the free vibrations of thin-walled, large-diameter oil pipelines, considering the influence of longitudinal force and the mass of flowing liquid. It confirms that these factors critically affect the structural reliability of the pipelines and therefore must be included in calculations. The numerical analysis was based on the semi-instantaneous shell theory, accounting for internal pressure, the thickness of the protective reinforced concrete layer, the soil’s spring constant, and the applied longitudinal force. The results showed that, during oil transport, the natural vibration frequencies of the pipeline decrease more rapidly than during gas transport. Increasing the thickness of the reinforced concrete shell and the internal operating pressure increases the frequencies and the overall stiffness of the system. The soil’s spring constant also place a significant role by offsetting some of the loads and increasing the vibration frequencies. The study confirmed that the longitudinal force has the greatest influence on the dynamic characteristics of the pipeline, leading to a significant decrease in the free vibration frequencies. The findings and established relationships should be used in the design and operation of large oil pipelines in heterogeneous soils to ensure the required stability and minimize the risk of resonance.

In structure of road transport operating costs, expenses for purchasing and storing spare parts can account for up to 45 %. Inventory management systems are most often based on analyzing past demand. A number of factors influence the range and quantity of spare parts needed: vehicle reliability, intensity and conditions of operation, demand, inventory availability at retail networks, and other considerations. At the enterprise level, the most significant criterion for inventory management is the total cost, which includes procurement, delivery and maintenance costs. This study revealed that there is no unified method for determining the optimal stock level of vehicle spare parts. The authors found that spare parts consumption is affected by operational intensity and vehicle reliability, as well as seasonal variations. Analysis of statistical data confirmed the seasonal dependence of spare parts stock levels. This dependence can be described by a harmonic model. It was found that there are some shifts in extreme values depending on the spare part group within a single season. More accurate accounting for these shifts can reduce inventory holding costs. The proposed approach to adjusting spare parts stock level norms in the warehouse will reduce the storage period of spare parts and, consequently, increase the efficiency of inventory management. Based on the studied statistical data, this efficiency is justified by a reduction in inventory valued at 470000 rubles per year. This method of adjusting spare parts stock level norms is applicable to both service and operational enterprises.

The process of updating regulatory documentation in the Russian Federation involves the implementation of a system of national and transitional national standards (GOST, PNST), and the phasing out of such forms of documentation as SP, ODM, etc. According to federal law, regulatory documents must not contain duplicative provisions. Currently, two standardized methodologies, based on domestic research findings and the Highway Capacity Manual standards adopted in the USA, are used to calculate saturation flow and traffic capacity at controlled intersections. These methodologies are formalized as industry road standards. The purpose of this article is to analyze the existing methodologies for calculating the saturation flow and the average delay per vehicle, as well as to compare the calculated saturation flow values from the presented documents using the example of regulated intersections. While the values of transport delays at intersections with a load factor below 1 are generally similar (calculation discrepancies are within 10%), a difference was found between the values obtained using Webster’s method and the method based on the Highway Capacity Manual when the load factor is equal to or exceeds 1. The incorrect application of these coefficients has a cumulative effect and affects the overall accuracy of calculations. Therefore, it is necessary to adopt a unified national standard for calculating saturation flow and traffic capacity, taking into account the findings of both domestic and international research.