Introduction. Managing firefighting operations requires considering numerous factors, including the shape and size of the fire area. In operational practice, simplified methods such as the tactical fire area calculation model are used. However, implementing this model in software is challenging, especially for objects with complex enclosing structures.

Goals and objectives. The goal of this work is to develop algorithms implementing the tactical model for calculating the shape and area of a fire. The tasks include analyzing existing methods, developing an algorithm that accounts for fire spread time, the configuration of enclosing structures, and the influence of firefighting equipment, as well as creating a tool for automating calculations.

Materials and methods. The algorithm is based on a modified Lee algorithm, used to model fire spread in a discrete space. It considers the linear fire spread rate, which depends on the fire development time and the deployment of firefighting equipment. A method for transitioning from a circular to a rectangular fire shape upon reaching walls was developed, along with a mechanism to account for the influence of firefighting equipment on fire progression.

Results and discussion. The algorithm demonstrated high accuracy (99 %) in constructing the fire area shape. The transition to a rectangular shape upon reaching walls aligns with the tactical model. Accounting for firefighting equipment allows modelling its impact on fire development. Comparison with the geometric method showed differences in fire area of less than 1 %. Key advantages include compliance with calculation rules, applicability to objects of any complexity, clarity, and consideration of equipment influence. Disadvantages include inaccuracies in the fire zone contour and accelerated fire spread in narrowing walls.

Conclusions. The algorithm is effective for modelling fire areas in accordance with the tactical model. The hypo­thesis regarding the use of a modified Lee algorithm is confirmed. For further development, cross-platform implementation, performance optimization, and additional experiments are recommended. The approach is applicable for predicting operational scenarios at facilities of various purposes.

Introduction. The issues of ensuring the fire safety of passenger transportation are important, in this regard, studying the level of fire load in the passenger compartment of railway transport and obtaining up-to-date data for modelling the development of fire is an urgent task. The existing regulatory system of fire safety requirements for interior decoration materials for passenger wagons, including textiles and upholstered furniture, requires significant clarification.

The purpose of these studies is to study the fire hazard parameters of textile materials and upholstered furniture products of salons passenger wagons, to develop proposals for clarifying regulatory requirements governing their fire safety and to obtain new fire load data when modelling fire development.

Research methods. Standard methods were used to determine the flammability of decorative fabrics (GOST R 50810–95), the toxicity indicator of combustion products and smoke-forming capacity (GOST 12.1.044.18), the methodology for assessing the fire hazard of subway car sofas (NPB 109) and the method for assessing the concentration of toxic gases on a small-scale experimental installation to determine the fire hazard of condensed substances and materials.

Research results and their discussion. Regulatory fire safety requirements for textile materials and soft products of interior decoration of passenger wagons were analyzed. Experimental data of estimation of fire hazard para­meters of curtains, upholstery materials and upholstered furniture elements of passenger car saloons are obtained. The danger of highly toxic gases emitted during thermal decomposition of upholstered furniture materials for the life and health of passengers and the need to take into account the values of their concentrations when modelling the development of a fire were revealed.

Conclusions. Proposals are developed to clarify the normative requirements for fire safety of textile materials and upholstered furniture products of passenger wagons saloons. There are presented the results of research of fire hazard characteristics of materials of seats, armchairs, sleeping shelves, which should be taken into account to exclude the use of the most dangerous ones in the saloons of wagons.

Introduction. The analysis of the explosion hazard of local changes in the time course in the Earth’s atmosphere (Poletaev, 2024) contributed to the development of relativistic research in the field of ensuring fire and explosion safety of facilities. The analysis was based on the dependence of the clock rate on the position of the clock in a uniformly accelerated reference frame (Einstein, 1907). It is reasonable to assume that local changes in the course of time are accompanied by local deformation of space (a visually observable change in the length of the ruler), which also becomes a sign of the appearance of local explosion hazard.

Problem statement and solution. The problem of the relationship (for a distant observer) of the relative changes in the movement of the clock and the length of the ruler associated with the clock, as they move in a homogeneous gravity field, is posed and solved. The basis of the solution was the law of equality of inert and heavy mass or correction of Newton’s law of gravitation, which allowed using a mathematical pendulum to establish the desired relationship. It is shown that, to the first approxi­mation, the relative change in the length of the ruler is twice as large as the relative change in the movement of the clock (hereinafter referred to as the correction ration).

Discussion of the results and conclusions. Changes in the local area of the Earth’s atmosphere are characte­­ri­zed by an increase (decrease) in pressure in the case of a decrease (increase) in the length of a standard ruler placed in this area. Significant (by orders of magnitude) explosive local pressure changes occur with a relative change in the length of the ruler in the range of ± 2×10–12. It is noted that the obtained correction ratio makes it possible to calculate, in a first approximation, some effects of the theory of gravity, for example, the angle of refraction of a ray of light by a heavy mass or correction of Newton’s law of gravitation, without involving the known equations of the gravitational field (Einstein, 1915).

Introduction. In the context of active Arctic development, ensuring fire safety has become a strategic task. Currently, there is a problem of hardening and breaking of sealing rings when the temperature drops to –40 °C, despite the declared operating temperature of –60 °C, according to the UHL-1 climate category. This can lead to difficulties and emergency situations during firefighting. Therefore, the development of frost-resistant sealing rings is a pressing issue. To extend their service life and improve aging resistance, it is necessary to incorporate anti-aging agents into the rubber compound formulation.

The aim of the research is to identify a suitable anti-aging agent for the formulation of frost-resistant sealing rings made from SKD-V butadienе rubber, designed for use in fire hoses and hydrants.

Objectives:
1. Determination of the effect of anti-aging agents on the properties of rubber compounds based on SKD-V butadienе rubber.
2. Investigation of the physico-mechanical and structural properties of elastomers.
3. Testing of the manufactured sealing rings based on the developed formulation under real operating conditions at the Ministry of Emergency Situations of the Republic of Sakha (Yakutia) and JSC “Vodokanal”.

Objects and methods of research. The study examined the elastic-strength properties, wear resistance, water resistance of the specimens, hardness, residual compressive deformation, thermal aging resistance and structural properties.

Results and their discussion. Antioxidants improved the elastic-strength properties, presumably due to the stabilization of the polymer network. However, when using IPPD, leaching and water discoloration were observed. Thermal aging reduced the elasticity of the specimens by 32–56 %, while combined systems demonstrated lower degradation, confirming their effectiveness. Laboratory and field tests verified the performance of the developed sealing rings in Arctic conditions in accordance with the UHL-1 climate category.

Conclusions. A frost-resistan.rubber compound was developed in the course of the study. A combination of anti-aging agents, Naftam-2 and Acetonanil, was selected.

Introduction. Plasticized compositions based on polyvinyl chloride (PVC) are used in virtually all sectors of the eco­nomy and are most often filled with silicates. A promising PVC filler is also wollastonite, whose needle-shaped
particles provide its reinforcing effect. The performance properties of composite polymer materials directly depend on their relaxation properties.

The aim. To study the dependence of molecular mobility of chains in PVC composites on their phase composition and structure of filler-silicates to reveal the relationship between relaxation and performance properties of poly­mer composites.

Materials and methods. In the current work, plasticized PVC compositions on the base of emulsion PVC, plasticizer EDOS, conventional fillers micro marble and Aerosil, and modifiers on the base of rice husk ash were filled. Dynamic mechanical method was used for the research as well as standard methods for assessing pores’ volume and size of applied fillers.

Results and discussion. The results of study showed that for both basic PVC composition and modified by silicon dioxide derived from rice husk ash (RHA) and synthetic wollastonite (SW) on its base, one maximum is observed corresponding to transition from glassy to highly elastic state. Regardless of the filler’s type, the shift of the relaxation transition occurs in the area of more elevated temperatures that correlates to the data on glass transition temperature of the polymer. The most prominent effect is provided by wollastonite with the developed crystalline structure, lowering the intensity of mechanical loss angle tangent in the region of the main maximum. The industrial filler Aerosil reduces the value of dynamic modulus of PVC compositions.

Conclusions. It was stated that treatment of rice husk ash surface with quaternary ammonium salts leads to lowering the glass transition temperature of PVC compositions due to decrease in ash porosity at activation. When the composition is filled with activated RHA, the width of the maximum of the tangent angle maximum of mechanical losses is reduced that demonstrates an increase in homogeneity of the modified material.