University of Civil Protection

This study presents the possibilities of using a fire extinguishing agent based on a water-soluble polymer for extinguishing fires at facilities where the fire load is formed by liquid combustible materials. It has been theoretically and experimentally shown that by changing the concentration of gelling additives, the viscosity can be varied, which, in turn, directly affects the characteristics of the protective layer created by applying the gel fire extinguishing agent to the surface of the combustible liquid.. The results of an experimental study of the effectiveness of gel fire extinguishing agents based on a polymer of the ECOFLOC A-18 type are presented. A method for preparing liquid solutions of concentrates of aqueous fire extinguishing agents with a gelling agent concentration of up to 10 %, which are easy to dissolve in water or in a foaming agent, is proposed. It is noted that their concentration should be such that when creating a working solution, the amount of gelling agent in it is not less than 0.05 % for the use of the solution in extinguishing fires.

The given article provides a comprehensive review of the issues related to the operation of fuel power generators in energy crisis conditions. The study is based on data from Ukraine, where, after beginning of the full-scale aggression of the russian federation in 2022, critical energy infrastructure facilities were destroyed or significantly damaged, leading to large-scale power outages across the country. In response to these challenges, the population began to use generators as autonomous power sources to meet their household needs. This has led to a simultaneous increase in the man-made risks associated with their use, including fire hazards, carbon monoxide poisoning, explosions of fuel systems, etc. The research covers a statistical analysis of the dynamics of fires over the past eight years (in particular, the time interval before and after the full-scale invasion of the aggressor country). The emphasis is on the period of 2022-2024, when the number of fires related to the use of electric generators increased to dozens per year. It is based on the official data of the State Emergency Service of Ukraine, according to which the main causes of such fires are short circuits and non-compliance with fire safety during the operation of electrical equipment. The paper analyzes the specifics of the use of electric generators in buildings and structures of various functional purposes, describes the main causes of fires during their use. It is found that the lack of differentiated standards for the placement and certification of equipment poses a potential threat to these facilities. Particular attention is paid to foreign incidents, in particular in the USA, Nigeria, Canada, India, and Australia, which demonstrate a similar typology of fire safety violations to Ukrainian realities, but in the context of effective regulatory control, they are more often localized in the early stages of fire development. In addition, the article highlights the problem of the lack of mandatory regulatory requirements in Ukraine regarding the location of generators, verification of equipment certification, and a national regulatory document on the rules for the arrangement and operation of fuel electric generators. With this in mind, the authors analyze the existing international standards governing the requirements for the safe installation, operation and maintenance of stand-alone power generators in countries with high fire safety standards. This comparison allows to identify gaps in the current Ukrainian legislation and to form a vision of the possible adaptation or integration of international experience into national practice in this area. Materials of the study can be used for further scientific understanding of the problem of operating fuel power generators, improving existing safety policies, developing regulatory documents for state supervision bodies, as well as in the work of designers and specialists in the field of fire safety.

The object of the study is an informative sign of detecting ignition of materials in premises based on the assessment of the bispectrum of a dangerous parameter of the gas environment. The problem is to develop a strategy for using the bispectrum to determine an informative sign of detecting ignition of materials based on the observation of an arbitrary dangerous parameter of the gas environment in the premises. It is proposed to determine a new informative sign by a measure of the average degree of "order" for each frequency in the spectrum of dynamics of an arbitrary dangerous parameter of the gas environment at a fixed observation interval. The proposed informative sign was experimentally verified by studying the spectra of the average degree of “order” of the dynamics of the main dangerous parameters of the gas environment during the ignition of materials in a laboratory chamber. It was established that during the ignition of materials, the values of the average degree of “order” of the dynamics of temperature and carbon monoxide concentration for all studied frequencies of the spectrum are significantly reduced and do not exceed the value of 0.1. This indicates a loss of the average degree of “order” for all studied frequencies of the spectrum of dynamics of temperature and carbon monoxide concentration. At the same time, the value of the average degree of “order” of the dynamics of the specific optical density of smoke with respect to the studied frequencies does not change significantly. The obtained results are useful from a theoretical point of view by using the bispectrum for an informative sign of ignition and a measure of the average degree of “order” for an arbitrary dangerous parameter of the gas environment. The practical significance lies in the possibility of further improvement of existing fire protection of objects in order to prevent fires.

The results of a study of chip formation during turning of hardened steels 40Kh, SHKh15, and R6M5 with a hardness of 50–65 HRC using a tool based on cubic boron nitride (CBN) are given. The effect of cutting modes and microgeometry of the working surfaces of the blades on the shrinkage and shape of the chip is shown. The change in the morphology of ground and diamond-lapped working surfaces of the blades during the cutting process is considered and the effect of its transformation on the dynamics of the turning process and the quality of the machined surfaces is shown. It is demonstrated that the morphology of the blade surface affects the processes of contact interaction between the tool and the workpiece materials, the shape of the chip and, after finishing, provides tribological contact conditions that reduce thermal stress and dynamic disturbance during a long cutting process.

This paper investigates evacuation procedures for preschool children aged 2–3 and 4–6 years, employing an individual-based flow model to accurately estimate evacuation times. Preschool-age children are particularly vulnerable during fires or other emergencies due to their limited mobility, diminished orientation skills, smaller anthropometric dimensions, and dependence on adults for guidance and physical assistance. Currently, Ukrainian regulations prescribe uniform evacuation parameters and movement speeds for all preschool age groups. However, these parameters fail to account for critical developmental and physical differences between toddlers (aged 2–3 years) and older preschool children (aged 4–6 years). Existing literature has extensively explored evacuation dynamics for older preschoolers, yet data on younger children's evacuation characteristics remain scarce, potentially resulting in inaccuracies in evacuation time estimates and compromising overall safety measures. This research addresses this significant gap by conducting a comprehensive analysis of current regulations, reviewing pertinent literature, and evaluating recent experimental data. A numerical simulation was performed using standard layouts of a typical two-story nursery school designed to accommodate approximately 200 children and 41 staff members. The model incorporated evacuation scenarios involving internal and external staircases. Simulations were conducted in two distinct scenarios: one applying uniform regulatory movement parameters across both age groups, and another using empirically derived, age-specific parameters for younger children (2–3 years). The study findings underscore the necessity of age-specific movement parameters. Results demonstrated a notable increase of approximately 35.8% in total evacuation time when age-specific parameters for younger preschoolers were applied. Specifically, evacuation times rose from 81 seconds to 110 seconds, emphasizing the critical importance of tailoring evacuation parameters to accurately reflect age-specific capabilities, thus enhancing safety measures for preschool children during emergencies. The research findings carry significant practical implications for fire safety management and emergency preparedness in preschool educational institutions. The implementation of differentiated movement parameters can substantially improve evacuation planning accuracy, inform architectural design optimization, enhance evacuation route efficiency, and guide targeted staff training and preparedness initiatives. Furthermore, given the increased frequency and urgency of evacuations in conflict-affected regions such as Ukraine, precise estimation of evacuation times is essential for safeguarding children and effectively mitigating risks during emergencies. Future research will involve controlled experimental evacuations to collect empirical data on movement speeds, flow densities, and capacities of children aged 2–3 and 4–6. These studies will also examine the impact of specific architectural elements, such as external evacuation stairs (type C3), to refine regulatory guidelines further and improve emergency preparedness protocols within preschool educational facilities.

Experimental studies of the fire extinguishing ability of systems based on bulk porous materials during acetone extinguishing were carried out. For this purpose, the experimental methodology for determining the fire extinguishing properties of such extinguishing agents, which was previously proposed for ethanol, was chosen. Crushed foam glass, granulated swollen perlite, and vermiculite were selected as bulk materials. As the bottom layer, which ensures the buoyancy of the fire extinguishing system, granular foam glass with a granule size of 10-15 mm was used. As the upper layer, which provides high insulating properties, we consider swollen perlite with a size of spherical granules with a diameter of 1-1.5 mm and swollen lamellar vermiculite with a linear size of 1×2 mm. The buoyancy of the selected bulk materials in acetone, their bulk density and moisture retention were experimentally determined. On the basis of the experimental results, the heights of the layers of dry and wetted bulk materials required for acetone extinguishing were calculated. It was found that the wetting of bulk materials leads to a significant increase in their extinguishing properties. This fact is explained by two factors: an increase in the insulating properties of perlite and vermiculite due to filling the voids between the perlite and vermiculite granules and a decrease in the concentration of acetone vapour due to its absorption by water. The introduction of water also increases the cooling properties of the fire extinguishing system. The lowest heights of fire extinguishing layers during acetone extinguishing are provided by the systems: wetted foam glass – 6.5 cm and foam glass (5.5 cm)+perlite (1 cm)+water. An expert evaluation of the complex parameter of the effectiveness of fire extinguishing agents for the selected fire extinguishing systems when extinguishing acetone was carried out. The best result was shown by wetted foam glass Further directions of research on the fire extinguishing characteristics of systems based on bulk porous materials and methods for establishing a complex parameter of the effectiveness of fire extinguishing agents are outlined.

A functional model of the pulse-width modulation device was developed to convert a continuous normalized input analog signal into a proportional output signal of the pulse-width modulation executive device of the fire protection system. An analysis of the scientific literature was carried out, which made it possible to take into account in mathematical models the use of pulse-width modulation of the control signal for controlling the operation of an inertial executive device, which was not considered before. A feature of the developed functional model is the use of pulse-width modulation of the control signal to control the operation of the inertial actuator. It has been proved that for the formation of the control signal of the operation of the executive device, the model of the device of pulse width modulation of the control signal must take into account the type, parameters of operation and structural features of the executive device. The study of the impact of the pulse-width modulated control signal on the executive device was carried out. The dependence of the signal spread at the output of the executive device with a given time constant on the dimensionless parameter presented in the logarithmic coordinate system is presented. The dependence of the spread and error of the signal at the output of the executive device with a given value of the time constant on the value of the control signal, the frequency of pulse-width modulation and the inertia of the real executive device is determined. A dimensionless criterion is proposed for determining the parameters of the pulse-width modulation of the control signal of the executive device with the given inertia and spread of the control signal. The results of the application of the functional model confirm the validity of the accepted hypothesis, and the calculated operating parameters of the executive device correspond to the experimental data. Recommendations for determining the parameters of continuous control of the executive device have been formulated.

The research focuses on developing a methodology to improve the safety of robots and manipulators in industrial environments. Robotic systems effectively perform complex and dangerous tasks, but at the same time create new risks for workers, which requires systematic assessment and management. An analysis of the main factors affecting the safety of robotic systems was conducted, in particular mechanical, ergonomic, thermal and electrical hazards. Based on this, a universal methodology for assessing occupational risks was developed, which takes into account the severity of possible injuries, the probability of their occurrence, personnel qualifications, the speed of danger onset and the level of awareness of workers. The methodology includes developed checklists, risk assessment matrices and questionnaires for identifying hazardous factors and determining the level of risks. To verify its effectiveness, a test was conducted at a machine-building enterprise, where the risks for employees working with the Absolute Arm 7-Axis measuring arm, the GLOBAL S GREEN 05.07.05 coordinate measuring machine and the ABB IRB 1400 M94A welding robot were assessed. It was found that the most dangerous workplace is the workplace of the ABB IRB 1400 M94A welding robot operator, because he is faced with mechanical, thermal, electrical, ergonomic, combined hazards and radiation hazards, the most important is the risk when the operator contacts live parts or connections, which is 51 (significant). The results showed the key risks at the workplaces, as well as the effectiveness of the developed measures to minimize them. Personnel training, restriction of access to hazardous areas and the use of personal protective equipment were introduced. The methodology can be applied to identify risks and implement safety measures at enterprises in various industries.

Due to the asymmetry of the material gradation, the neutral surface in functionally graded (FG) beams is dislocated from the mid-plane, so mid-plane-based model may lead to inaccurate results in FG material (FGM) beam analysis. However, a little attention is paid to the neutral surface-based vibration in FG beams, especially when the material properties are temperature dependent. This study addresses the analysis of the neutral axis (NA) position effect on fundamental frequency of FG Timoshenko beams with temperature-dependent properties under nonlinear temperature rise. First, a formula for exact position of the neutral surface in the temperature-dependent beams is derived for general nonlinear temperature rise distribution and power law of material grading. Then, the dislocation of the NA from the central one is examined along material grading index and various temperature distributions. Finally, the effect of exact NA position and temperature distributions on fundamental frequency is investigated to reveal when the NA position and nonlinear temperature distribution should be considered in vibration analysis of the beams. The main results obtained in this study are that the exact position of NA is derived in an analytical expression for temperature-dependent FG beams and its effect on fundamental frequency of the beam is examined. Numerical analysis shows that the exact position of the NA has a significant impact on natural frequency and it cannot be ignored in the thermal vibration analysis of FG beams, especially in the case of high-temperature environment.

The article examines the issues of coordination between public administration bodies in the field of internal security in Ukraine, using the example of the State Emergency Service of Ukraine (SES). The systematic organization and powers of key entities ensuring the internal security of the state are analyzed. The main shortcomings of interagency interaction are identified, in particular, duplication of functions, lack of effective mechanisms for information exchange, unclear distribution of powers between the national and local levels of government, and insufficient synchronization of actions during response to emergencies. Based on the analysis of real cases from the practice of the SES functioning in the conditions of modern challenges, a set of management solutions is proposed to increase the effectiveness of coordination: the creation of unified interagency operational centers, the implementation of integrated information and analytical systems, the improvement of the regulatory and legal framework for interagency interaction, the development of standardized protocols for joint actions, the formation of a system of continuous training of personnel for work in interagency coordination. Promising directions for the digitalization of internal security management processes and the possibilities of adapting positive European experience to Ukrainian realities have been identified.