Advances in Science and Technology Vol. 170

Abstract: The issue of dewatering sand, which is used in construction as an aggregate for heavy, simple, fine-grained, large-cell and silicate concrete, concrete mixtures, in the manufacture of reinforced concrete structures, in the production of asphalt and road surfaces, roofing construction materials, in the manufacture of glass, is considered. The results of experimental studies of the operation modes of the process of dewatering construction sand at drainage warehouses with the use of vacuum units are presented, depending on the time of its dewatering, the granulometric composition of the sand, and the placement scheme of special needle filter elements of the suction system.

Abstract: This study analyzes the impact of high temperatures on the physico-chemical properties of concrete, highlighting a marked decrease in strength and material integrity. Among the mechanical non-destructive testing methods, the rebound hammer technique was selected for its accessibility, speed, and capacity to deliver preliminary on-site results. Field data obtained at fire-damaged sites reflect the extent of material degradation and enable the identification of critical heat-affected zones and potential fire origin points. By comparing the strength of concrete in damaged versus intact areas, the most severely affected zones can be identified.

Abstract: The results study of the accuracy of the temperature fire measurement by the sensors of the fire alarms in dynamic conditions with random temperature fluctuations, are presented. The statistical study of the accuracy measurement is based on the method of transformation of the random processes by the linear systems. The constructive approaches to optimizing and the accuracy improvement of the thermal sensors with the thermo-resistant sensitive element and the bridge measuring circuit in the dynamic conditions under random temperature fluctuations based on the choice of corresponding values of the characteristic parameter of the sensor and the constant time of its sensitive element have been proposed. Scientific novelty of the results is in the development model and in the method of analysis of the dynamic model of the thermal sensors with the thermo-resistant sensitive element in the form of a thin plate. It has been proved that the invariance of the accuracy of the ambient temperature measurement over time is possible. The obtained results allow solving the practical tasks determining the optimal parameters of the sensors under the conditions of fire temperature dynamics, taking into account the background random temperature fluctuations.

Abstract: The objective of this work is a solution search to enhance the accuracy of explosive gas and vapor detection devices within explosion hazard monitoring systems for technogenic environments. The study employs analytical methods for investigating the operation of thermocatalytic sensors under various power supply modes of their sensitive thermoelements, based on classical principles of electrical engineering, thermodynamics, and catalysis, as well as experimental studies of sensor performance under different supply conditions, followed by evaluation and generalization of the theoretical and experimental results. It has been established that when the measuring bridge of thermocatalytic sensors is powered by a constant voltage supply, or under modes with voltage stabilization across the active or reference thermoelement, a stable thermal regime of the active thermoelement is not maintained. This leads to significant measurement errors in determining the concentration of flammable gases or vapors of volatile combustible liquids. Furthermore, under explosive concentrations of combustible components – such as those that may arise during emergency situations – voltage-stabilized power modes across the bridge or reference thermoelement may result in sensor damage due to overheating of the active thermoelement. It is shown that the risk of thermal overloads is eliminated, and minimum measurement errors are achieved when the power supply mode ensures a stable temperature of the active thermoelement. The optimal power supply mode for the thermocatalytic sensor has been substantiated. It is based on stabilizing the resistance of the active thermoelement, which ensures a stable thermal regime of operation, eliminates the risk of thermal overloads, and significantly reduces measurement errors in determining the concentration of combustible components caused by changes in working conditions. For the gas analyzer's that implements a procedure for checking and adjusting the temperature regime of the active thermoelement the operating mode algorithm has been proposed. The studies, that have been conducted, significantly enhances the reliability of explosion hazard monitoring systems at technogenic sites and reduces the risk of hazardous situations caused by leaks of flammable gases and the accumulation of vapors of volatile combustible substances that may lead to explosions.

Abstract: The main technical requirements for the development of an electromagnetic detection method for explosive materials are considered. The main elements of interference that increase the detection error are classified. The probability of detecting explosives at different soil depths is modeled. It was found that the frequency of the scanning signal has the greatest influence. Thus, reducing the scanning frequency increases the probability of detecting an object. However, reducing the irradiation frequency is limited by the resolution for objects of a given size. It is shown that reducing the dielectric constant of the soil does not lead to satisfactory detection probabilities even in the upper soil layer. In the size range of real explosives (0.1–0.5 m), the detection probability decreases by 10-25%. The analysis of the characteristic time signatures of explosives imitations showed that the development of a database of such signatures will reduce the number of false signals. An algorithm for the implementation of the method of electromagnetic detection of explosives consisting of 18 functional blocks and three logical blocks has been developed. The obtained results made it possible to describe the procedure for detecting explosive materials in a contaminated area. The use of the obtained results in humanitarian demining will increase the speed of surveying the territory, increase the probability of detecting explosive objects and reduce the risk of injury to personnel conducting humanitarian demining.

Abstract: The paper explores the problem of optimizing groundwater sampling in areas affected by multiple rocket launcher systems (MRLS). Taking into account modern challenges to the safety of the population and the environment in the conditions of hostilities, an express method of preliminary zoning of groundwater pollution based on the measurement of electrical conductivity has been proposed. The method is based on modeling the spread of contaminants in combination with cluster analysis of these measurements. The results of the study can be used for operational monitoring of territories affected by hostilities and in management decision-making systems in the field of civil protection.

Abstract: The research paper is devoted to the study of the efficiency of biological methods of wastewater treatment, which are among the main pollutants of surface water bodies. The article also focuses on phytoremediation technologies using microalgae, which differ from existing technologies by their high efficiency and relatively low cost, combined with the production of biodiesel from microalgae biomass. The phytoremediation technology of purification from biogenic elements provides increasing environmental safety of food industry enterprises. An example of calculation is given, demonstrating the environmental effect of the developed cleaning technology. Further research and the use of this technology to produce treated water that meets standards is designed to preserve the environment in order to reduce the burden on natural resources and meet sustainable development goals.