Petersburg State Transport University

Objective: to explore how temperature variations influence ultrasonic vibration attenuation in rail steel. To propose a methodology for evaluating thermal stresses in continuous welded rails by analyzing the amplitude variations of ultrasonic signals transmitted through the rail structure. Methods: the theoretical fundamental principles governing the propagation of ultrasonic waves were examined, with a specific focus on how rail temperature conditions impact on the ultrasonic signal amplitude. Field measurements were carried out to verify the theoretical data. Results: a distinct correlation has been established between the rail temperature and the attenuation of ultrasonic vibrations transmitted through the rail. A mathematical expression describing the dependence of ultrasound amplitude on the temperature of the rail steel has been obtained. The study has identified specific variables that could compromise measurement precision. The data demonstrates that integrating temperature-dependent variables into ultrasonic amplitude analysis is crucial for enhancing the precision of current methods used to estimate thermal stresses in continuous welded rail systems. Practical significance: the findings of the study will allow the development of more accurate and reliable methods for monitoring thermal stresses in continuous welded rail tracks, and can be used to improve existing techniques for detecting thermal stresses in continuous welded rails.

Objective: to provide additional case studies of verification analysis for cantilever stone staircases in the context of structural surveys. Materials and methods: the case studies employ mathematical modelling techniques and draw on empirical data obtained from prior investigations. Results: the selected examples highlighted distinctive aspects of these structures. The analyses and interpretation of the findings have been carried out with consideration of their future implementation in practical projects. Practical significance: this paper aims to furnish practicing engineers with methodological guidance to support the conservation of historically valuable structures.

Objective: to examine the issue of accelerating freight shipping fl by rail. To achieve this objective, key factors that negatively aff delivery speed were identifi. Methods: collection, comparison, and systematization of data on the operating speeds of freight trains. Results: the research concluded that a differentiated approach is required for the development of measures to accelerate freight transport fl as well as a comprehensive strategy is necessary to address the specifi challenges of per-wagon load consignments. A classifi of factors aff freight delivery speed has been proposed, and the principal directions for measures to increase train speeds have been substantiated. It is emphasized that acceleration of fl is directly infl by organizational arrangements, technology, data culture, the scaling of digital technologies, and personnel qualif. Practical importance: the study demonstrates the necessity to revise existing approaches to train scheduling and to develop adaptive, forecast-driven digital models. A comprehensive scientifi approach to logistics optimization and transport management, together with the deployment of intelligent AI-based solutions in transportation, can signifi improve rail-freight delivery speed.

The article discusses the features of modeling of train movement with clarification of the results of traction calculations. Purpose: modification of the train movement equation taking into account random factors based on processed statistical data for use in dynamic models. Methods: mathematical modeling, probability theory, Euler, Runge — Kutta methods. Statistical hypotheses are tested about the belonging of real trip registration data and data obtained by modeling to one general population. Results: during the analysis of statistical data obtained from recording cassettes and high-speed tapes, it is proposed to clarify the existing equation of motion with correction coefficients obtained empirically. A hypothesis is put forward that statistical and calculated data belong to one total population. Practical significance: as a result of confirming the hypothesis, the modified equation of motion can be used when modeling the movement of the flow of trains with various dynamic characteristics, including when arriving and departing at stations, as well as determine the actual values of station and inter-train intervals.

Objective: to identify the main technological approaches for treating urban wastewater sludge that will enable production of marketable products and generation of economic benefits. To present sludge treatment methods that, in addition to producing marketable outputs, will prevent environmental contamination. To justify the selection of technological schemes for sludge treatment in accordance with current legislation, taking into account the impact of liquid effluents released during treatment on the operational efficiency of municipal sewage treatment plants. Methods: a comprehensive analysis and systematization of existing regulatory documents concerning the treatment, disposal and elimination of sediments generated during urban wastewater treatment were undertaken. A comparative assessment was conducted of the effects that various sludge treatment technologies exert on the mechanical and biological treatment facilities of municipal sewage plants. Results: contemporary criteria for evaluating the effectiveness of technologies for treating and disposing of urban wastewater sludge were considered. A minimal required sequence of sludge treatment stages has been proposed to prevent adverse environmental impacts during both sludge treatment and disposal. The principal modern structures and devices for sediment processing, have been identified, which, both immediately upon implementation and over the long term, will contribute to improving the environmental performance of municipal sewage plants. Devices and structures suitable for modernization and/or reconstruction have been identified. Their upgrade will permit the production of market-demanded products at the final stages of the sludge-processing chain. Practical significance: the findings reflect current trends in sludge management, evidencing a shift from the obligatory basic dewatering toward opportunities and imperatives for generating revenue from sludge disposal. The proposed measures to improve sludge disposal efficiency at municipal sewage treatment facilities, based on best available technologies, will minimize adverse environmental impacts. The proposed technological schemes for processing sediments from urban treatment facilities will ensure compliance with contemporary environmental safety requirements while maintaining economic efficiency.