Context. In special conditions, particularly during emergencies, when satellite and terrestrial communication channels become vulnerable or completely unavailable, communication via meteor burst channels can effectively serve as a backup or even a primary path for information transmission. The operational range of such a radio channel can reach up to 2000 km, and the absence of "dead zones" ensures broad territorial coverage that is comparable to other types of long-range radio communication. Objective Improvement of the method for one-way message transmission via meteor burst communication channels and its implementation algorithm, enabling minimization of message delivery time at a given reliability level. Method. Further development was achieved for the method based on minimizing the message structure through merging the address field with the synchronization flag. Additionally, a hybrid synchronization algorithm combining threshold and non-threshold signal processing is applied for the first time. To enhance reliability, the majority algorithm is utilized instead of classical ARQ methods through repeated message transmission. Results. An improved method for alert transmission over meteor-burst channels has been proposed, ensuring minimized delivery time and high reception reliability. Based on this method, a transmission protocol was developed, the message delivery time was evaluated, and synchronization techniques were identified, confirming the method's effectiveness. The practical value lies in the development of an implementation algorithm suitable for deployment on DSP and FPGA platforms in alert systems without relying on satellite communication channels. Conclusions. The proposed method and implementation algorithm enable the minimization of short message delivery time at specified reliability level and improve communication reliability under challenging conditions.
The main goal was to study the stress-strain behaviour of cylindrical and spherical concrete shells. A full-scale experimental setup was developed to simulate uniformly distributed and concentrated loads on cylindrical and spherical shell fragments. Measurements of displacements at 25 points allowed to carry out an accurate analysis of the deformation behaviour. The maximum displacement under a load of 10 kN/m2 was 0.242 mm for the cylindrical shell and 0.78 mm for the spherical one. The experimental results were verified using finite element modelling in ANSYS software, which showed a maximum deviation of 15-17% between the theoretical and observed displacements. Compared to traditional reinforced concrete shells, the optimized design provides a 47% decrease in material consumption (reinforcement and concrete), a 50% decline in the equivalent thickness of the structure, and a 35% cut in relative costs. This opens a promising path that provides material efficiency, potential cost savings, and reduces the carbon footprint, supporting sustainable development goals in the construction sector.
Purpose. To conduct a comparative analysis of the technical condition of the bodies of universal and specialized gondolas (with a blind body) owned by state and private operators. To determine the structural elements of the bodies that fail most often and pose a threat to traffic safety. Methodology. The study was conducted using statistical data on failures of universal gondolas owned by JSC «Ukrzaliznytsia» and private operators during operation over the period 2022-2024. For this purpose, data on wagons of various models and different service lives entering scheduled types of maintenance and repair were analyzed. During the study, classical methods of mathematical statistics and the well-known Microsoft Excel application package were used. The analysis made it possible to determine which models of gondolas prevail in the general fleet of cars and to establish which main structural elements of universal gondolas bodies fail most often. Findings. A statistical analysis of failures and damage to the bodies of both universal gondolas and specialized gondolas with a solid body of different models was carried out, taking into account the service life. The results obtained made it possible to compare the technical condition of universal gondolas bodies of different models, as well as to compare the technical condition of universal gondolas and specialized gondolas with a solid body. It was established that the most common types of damage to universal open-top freight wagons include failures of welded joints of vertical posts, damage to the covers of unloading hatches and their locks, cracks and fractures of the vertical sheets of the transverse beams of the frame. Originality. For the first time, a comparative analysis of damage occurrence of different models of gondolas was carried out and the dependence of the number of failures on the service life was determined. Practical value. The results obtained make it possible to determine the directions of development of new technical solutions for improving gondola bodies. Based on the analysis conducted, taking into account the actual technical condition of the gondolas and the level of their damage depending on the model and service life, it is possible to form an improved strategy for restoring the operability of gondolas by optimizing the timing of repairs and maintenance.
The article proposes an integrated approach to prepare passenger cars for operation considering resource constraints and seasonal fluctuations in passenger traffic. The study is based on an analysis of the operational data on the volume of passenger car washing and water consumption during the period 2017-2024. The work uses methods of statistical analysis, regression modeling and numerical optimization. A close correlation between the number of passenger cars in the train and water consumption has been established, which allowed the formation of the corresponding regression dependencies and their integration into the structure of the optimization model. A mathematical model has been developed considering the time, resource and labor parameters of the process of preparing passenger vehicles and ensures a rational allocation of resources. The objective function combines time costs and the cost of processes using weighting factors, and the system of constraints considers technological, resource and organizational aspects. The model is adapted to variable operating conditions and provides for the possibility of scenario analysis. The results of the study showed that the use of automated passenger car wash complexes allows the reduction of water consumption by 10-12% and reduces the duration of washing by up to 20%. The use of the optimization model ensures a reduction of the total time for train preparation by 18-22% and a reduction in operating costs by 12-16%, which indicates an increase in the efficiency of resource use. Additionally, it was found that the introduction of automated technologies contributes to the reduction of the negative impact on the environment by reducing water consumption and reducing the level of wastewater pollution. The results obtained confirm the effectiveness of the proposed approach and the feasibility of its application in passenger cars' maintenance systems.
