Advances in Science and Technology Vol. 172

Abstract: The article presents the results of a study of the physical and mechanical properties of a biopolymer gravel composite made on the basis of polylactide (PLA) and natural gravel. The developed composite is intended for filtration elements of hydrogeological wells. The biopolymer-gravel composite was tested for compressive strength. The results showed that the biopolymer gravel composite is characterized by sufficient mechanical strength and resistance to the effects of the aquatic environment, which confirms the feasibility of its use as an environmentally safe material for filtration elements of hydrogeological wells. The obtained data can be used for further optimization of the composition of the composite material and the development of new biopolymer block gravel filters of hydrogeological wells.

Abstract: This study analyzes the global experience with trolley-assist haul trucks in mining, substantiates their feasibility for Ukrainian open-pit mines, and develops a mathematical model describing the dependence of economic effect on the electrification coefficient (k_e) of haul roads. The methodology involves analyzing technical and operational data from Canada, Finland, Zambia, and South Africa, adapting it to Ukrainian conditions, and modeling the integral economic effect. The dependence is described by a saturating Hill function, with parameters determined via the least squares’ method using empirical and calculated data. Results show that a combined diesel–trolley system offers an optimal balance between economic efficiency, productivity, and capital costs. The model identifies an optimal k_e range of 0.20–0.40 for Ukraine, achieving 70–80% of the full electrification benefits. The analysis confirms nonlinear growth of the effect and saturation beyond k_e≈0.40. For the first time, global operational data have been integrated with modeling for Ukrainian open pits, producing a tool adaptable to various mining and geological conditions. The methodology supports phased electrification, fuel savings of 25–30%, CO₂ reduction by 20–25%, and substantial productivity gains.

Abstract: Comparison of experimental and calculated data of the excavator utilization factor in time (K_u) according to the current methods showed the absence of even a correlation between them r = 0.17, which indicates the inexpediency of using the basic models that are the basis of these methods. The reason for the low correspondence is that the excavation processes are complex random dynamic non-stationary processes, and the models that are the basis of almost all current methods are simple deterministic static models that cannot successfully operate at the level required for such processes. In the work with the application of the theory of mass service systems, a set of probabilistic dynamic non-stationary models in the form of Markov-Kolmogorov equations was developed to describe the probability of states, both for each of the selected subsystems of downtime of excavation works, and for the “excavator face” system as a whole. Comparison of the actual values of the coefficient (K_u) obtained as a result of the experiment allows us to recommend the developed set of models as the basis of the methodology for calculating K_u (r = 0.70).

Abstract: This study presents integrated methodology for using RTK and non-RTK UAV systems in open-pit mining surveying. Three experiments were performed using DJI Mavic 3E RTK and DJI Mini 3 Pro drones at an altitude of 61.5 m with an overlap of 80%×75% over identical sites. A network of 12 precisely located control points allowed for a comparative assessment of the accuracy between RTK+GCP, non-RTK+GCP, and RTK-only configurations. Statistical analysis using multivariate analysis of variance (ANOVA) confirmed the significance of the positioning technology for survey accuracy. The RTK system achieved RMS errors of 2.88-5.23 cm versus 17.27-22.94 cm for non-RTK systems, representing a 5-6-fold increase in accuracy. This comparison demonstrates that RTK without ground control points maintains comparable accuracy (5.23 cm) to RTK with control points (4.45 cm), while reducing operating costs by 84%. Analysis of camera position accuracy showed an accuracy of 2.04-2.06 cm RMS regardless of the use of control points. These results confirm that RTK methodology is cost-effective for standard surveying, achieving geodetic-grade accuracy without traditional field support infrastructure. The methodology allows for continuous monitoring of mining operations while reducing costs and increasing accuracy.

Abstract: An interface crack between two semi-infinite piezoelectric/piezomagnetic media under out-of-plane mechanical load and in-plane electric and magnetic fields parallel to the crack faces is examined. A portion of the faces is electrically conducting and kept at a uniform magnetic potential, while the remaining portion is electrically and magnetically permeable. The coupled fields are represented by functions analytic in the plane outside the crack. With these representations, the mixed crack-face conditions lead to a combined Dirichlet–Riemann and Hilbert boundary-value problem, which is solved in closed form for arbitrary conductive versus permeable segment lengths. The solution yields explicit expressions for stresses, electric and magnetic fields, and the crack-face sliding (displacement jump). The singular behavior at both crack tips and at the transition between conducting and permeable zones is characterized, and intensity factors are defined accordingly. Parametric results illustrate how applied electric and magnetic fields modulate the fracture driving force; in particular, suitable magnetic loading can markedly reduce the mechanical stress intensity at the permeable tip. The formulas supply benchmark data for verification and enable design guidelines for tailoring electrode coverage and field application to mitigate interface fracture. The approach provides an analytic framework for mixed electromagnetic conditions in magnetoelectroelastic interface fracture.

Abstract: The widespread use of aging materials in engineering, along with the growing demands for reliability and cost-effective design, poses new challenges for researchers in improving mathematical tools, methods for describing experimental data, and developing both exact and approximate solution techniques for specific problems. This paper investigates the stress distribution in a viscoelastic rotating disk of variable thickness mounted on a rigid shaft. An approximate method is proposed for solving the governing differential equation with variable coefficients, based on the use of canonical polynomials and the τ-method of Lanczos. The resulting polynomials obtained using this approach approximate the desired solution approximately 2n times more accurately than hypergeometric functions. The generalization to the viscoelastic case is achieved by applying the Volterra principle. A numerical example is provided. The scientific novelty lies in the application of canonical polynomials and the τ-method instead of hypergeometric functions to solve the stress analysis problem of a rotating viscoelastic disk with variable thickness. The canonical polynomials – either in general form or numerically determined using the relationships derived in this study – can also be constructed for other similar problems.

Abstract: The study focuses on optimizing the design of respirator filter cartridges against particles to minimize their impact on ergonomic performance. The aim is to determine the uniformity of airflow distribution in the filter. Numerical analysis in SolidWorks Flow Simulation was applied to assess the effect of design parameters. Covers with a round inlet, smooth edges and an inner surface ensured the most uniform flow and reduced pressure drop. Cartridges with a central outlet showed higher velocity (by 10 %) and pressure (by 15 %) variation than those with an offset outlet, as air moves directly to the centre. Increasing airflow from 30 l/min to 95 l/min improved uniformity, reducing velocity variation to 25 % and pressure to 30 %. The outer cover and geometry of the cartridge were proven to influence airflow distribution, ensuring efficient use of the entire filter surface. With elliptical and square inlets, velocity variation increased from 30 % to 50 % compared to round inlets, due to asymmetrical pressure distribution. The scientific value lies in identifying the influence of inlet/outlet geometry on airflow velocity and pressure distribution, while the practical outcome is defining optimal inlet dimensions for efficient, comfortable respirators.

Abstract: The rheological properties of drilling fluids, such as plastic viscosity, yield point, and gel strength, are critical for ensuring efficient and safe oil and gas well drilling. Traditional methods for rheological analysis, reliant on manual or semi-automated viscometers, suffer from delays and inability to provide continuous data, increasing operational risks. This study presents the development and validation of an automated software-hardware complex designed for real-time monitoring of drilling fluid rheology. The system integrates inline rheometers, pressure and temperature sensors, and advanced data processing algorithms to deliver accurate measurements with a response time of 0.8 seconds. Laboratory tests demonstrated errors of ±4.2% for viscosity and ±7.8% for yield point compared to the Fann 35 viscometer, while field tests under simulated drilling conditions (30–100°C, 5–20 MPa) confirmed reliability with errors below ±9.2%. Case studies showcased rapid detection of anomalies, enabling proactive fluid management. The complex offers a scalable, integrated solution, reducing non-productive time and enhancing well stability. Recommendations include machine learning integration for predictive analytics and cloud-based analytics for remote monitoring, with future work targeting extreme conditions and other fluid types. This advancement significantly improves drilling fluid management, contributing to safer and more efficient drilling operations.

Abstract: The risk management process has been improved, which, unlike the known one, provides for procedure for making management decision on the expediency of accepting, reducing, rejecting and transferring unacceptable or acceptable risk using different PDCA cycles types: circular and/or spiral, diverging or converging. It is proposed to combine the procedure for improving the risk management process itself using circular and spiral PDCA cycles with the procedure for management decision making, which will ensure timely detection and prevention of possible subjective biases influence on the results and conclusions obtained. The scientific novelty lies in identifying relationship between management decision made based on risk level assessment (acceptable or unacceptable) and revision (update) of estimated risk levels and risk management procedure itself based on the application of circular and spiral PDCA cycles, which create conditions for improving the risk management process. Practical value lies in development of eight combinations hierarchy of management decisions, depending on risk level (acceptable/unacceptable) and four types of management decisions regarding acceptable and unacceptable risk levels: accept risk, reduce risk, transfer risk or refuse risk; and corresponding management decisions matrix has also been developed.

Abstract: Safety, by definition, is a state of protection against hazards, which implies measures for reduction/evasion/exclusion of risks. Safety is relative, depending on the degree of implementation of measures in specific conditions. The concept of security should only be considered as a result of risk management. Modern risk management practice is the basic risk levels and balancing between the need to ensure a certain level of security and the economic feasibility of investment in security measures. In practice, despite the declared safety priorities, industries are balanced between investment in security and an acceptable level of risk, without considering the nature and degree of influence of security measures at the stage of their development. This method of balancing is characterized by the desire of business to formally meet the general standards of risk management in order to minimize costs, minimize social and other types of responsibility, for the sake of maximizing income, which is a common problem. This problem is particularly acute in the context of national and industrial security.