The demand for an improvement in the tribological properties of lubricants used in various industrial plants, the automotive industry, and other power transmissions has resulted in the development of a whole family of improved lubricants based on nanotechnology. Especially important are nanotube additives, which significantly improve the tribological properties of lubricants, primarily by reducing the friction coefficient and wear of the coupled elements but also by reducing the temperature load and increasing the stability of the oil film between the lubricated surfaces. The properties of nanotube-based additives were further improved using elements such as metal oxides and compounds based on titanium, molybdenum, aluminum, etc. This paper presents the results obtained in the field of research and application of nanocomposite lubricant additives. It also gives a partial comparative analysis of the research conducted in this field. The primary goal of this paper is to analyze the research results in the field of the application of nanotubes in lubricants and to indicate the importance of their application, such as improving the tribological properties of machines and reducing power losses. Furthermore, this paper shows the negative impact of nanoparticles on the environment and human health and the costs of applying some types of nanoparticles.

Worm gears are used in various mechanical constructions, especially in heavy industrial plants, where they are exposed to high operating loads, large torques, and high temperatures, particularly in conditions where it is necessary for the input and output shafts to be at an angle of 90°. Regarding tribological optimization, the application of carbon nanotube in lubricants can lead to significant improvements in the performance characteristics of worm gears, both in terms of increasing efficiency and reducing the coefficient of friction and wear, as well as minimizing mechanical losses, noise, and vibrations. The objective of this study is for the research results, through the use of oil with varying percentages of carbon nanotube additives (CNTs), to contribute to the optimization of worm gears by improving efficiency, extending service life, and reducing vibrations—both within the gearbox itself and within the industrial facility where it is applied. The research methodology involved laboratory testing of a worm gear using lubricants with varying concentrations of carbon nanotube. During the experiment, measurements of efficiency, vibrations, and noise levels were conducted in order to determine the impact of these additives on the operational performance of the gear system. The main contribution of this research is reflected in the experimental confirmation that the use of lubricants with optimized concentrations of carbon nanotube significantly enhances the operational performance of worm gears by increasing efficiency and reducing vibrations and noise, thereby enabling tribological optimization that contributes to improved reliability, extended service life, and enhanced workplace ergonomics under demanding industrial conditions. Furthermore, experimental investigations have shown that the efficiency of the gearbox increases from an initial value of 0.42–0.65, which represents an increase of 54%, the vibrations of the worm gear decrease from an initial value of 5.83–2.56 mm/s², which represents an decrease of 56%, while the noise was reduced from 87.5 to 77.2 dB, which represents an decrease of 12% with the increasing percentage of carbon nanotube additives in the lubricant, up to a maximum value of 1%. However, beyond this experimentally determined threshold, a decrease in the efficiency of the tested worm gearbox, as well as an increase in noise and vibration levels was recorded.

This paper presents the results of experimental tests of the efficiency of a single-stage worm gear. Two worm drives were used for testing, where the worms are made of improved steel 42CrMo4 and the worm gears are made of tin bronze CuSn12 and aluminium alloy A356. The values of the efficiency were determined at different values of revolutions and loads, where oils of different viscosities were used for lubrication. Determining the efficiency, the coefficient of friction of worm drives was calculated for experimental operating conditions, as well as the mass measurement of worm gears before and after testing. Based on the experimental results, depending on the operating mode and oil viscosity, the values of the efficiency of the worm drive made of the material 42CrMo4/CuSn12 are higher by 5 to 9 % compared to the worm drive 42CrMo4/A356. Higher values of the efficiency of the worm drive 42CrMo4/CuSn12 cause lower values of the coefficient of friction by 14 to 21 % as well as less wear of the worm gears.

In this paper the impact of square opening, as a source of stress concentration, on the distribution of stress in parts of machines and devices is considered. The fact is that these forms of the openings occur less in practice, but the knowledge of t...

The selection of an appropriate operating system (OS) in educational environments is a critical decision that impacts the functionality, user experience, and overall efficiency. Financial factors, along with the availability and functionality of tools used on these systems, play a crucial role in this selection. Furthermore, the OS affects the user experience, security, and adaptability to learning. Previous research in this area is scarce, and this paper contributes to a better understanding of the OS selection process in education. This paper proposes a novel multi-criteria decision-making approach to evaluate and select the most suitable OS for educational institutions. The methodology integrates the PIPRECIA method for assessing weighted criteria, alongside utility analysis (NWA), enabling a balanced decision-making process between institutional management and IT experts. The evaluation considered the following criteria: performance, cost, security, usability, implementation, support, and documentation. The study compared three popular operating systems: Microsoft Windows 11, GNU Linux Ubuntu 22.04 LTS, and Apple macOS 12 using the proposed approach. The results, based on the integrated evaluation of all criteria, indicate that GNU Linux Ubuntu 22.04 LTS (0.562) ranked highest, followed by Microsoft Windows 11 (0.553) and Apple macOS 12 (0.543). This paper emphasizes the importance of objective, group-based decision-making in selecting an OS for education, providing practical insights and guidelines for effective technology integration in academic settings.

This study examined the effect of abrasive action on the surface roughness and mass loss of laminate composites produced by the wet lay-up method. The paper describes in detail the production process of these composites and after the production process, the surface was analysed using an optical microscope. Surface roughness was monitored in the transverse and longitudinal directions, before and after processing with P3000 grit sandpaper, where a significant increase in roughness was observed with minimal mass loss. A more detailed analysis of mass loss included precise measurements in the time interval from 1 to 5 minutes, with the results showing that with extended grinding time the amount of worn material increases. Additionally, analysis using an optical microscope confirmed the successful production of laminate composites, with very little presence of trapped air bubbles recorded, indicating the high efficiency of the applied production process. Considering the characteristics of the used epoxy resin, the obtained results indicate high wear resistance of laminate composites, which is crucial for achieving aesthetically attractive components.