The numerical simulation and analysis of the ejection of an ink droplet through a nozzle as well its motion through air until its contact with a surface and taking up of a stable form is performed. The fluid flow is modeled by the incompressible Navier–Stokes equations with added surface tension. The presented model can be solved using either a level set or a phase field method to track the fluid interface. Here, the level set method is used to determinate the interface between ink and air. The presented work concentrates on the demonstration how to check the suitability of ink for inkjet printhead nozzles, for instance, for the use in printers. The results such as velocity, change of size, and volume dependence on time of an ink droplet are presented. Recommendations for the use of specific inks are also given.

The possibility of using powder spraying to improve the strength properties of polymer concrete products has been studied. Different compositions of polymer concrete mixtures have been compared and analyzed in order to find out the adhesive and cohesive properties of coatings. An analysis of the stress-strain state under static loads has been carried out. To improve the tribological properties and wear resistance of critical parts of metal-cutting machine tools, such as beds, it is proposed to spray polymer concrete surfaces using the gas-thermal method. Two types of powder mixtures for spraying have been compared, and the adhesive properties of the analyzed coatings have been considered. The finite element method was used for the calculation of the abrasion resistance of polymer concrete models according to the proposed modification of Ni-7Cr-3Fe + 60% WC coating composition, which showed that the use of gas-thermal coating for polymer concrete is justified. Based on a simulation of adhesive peeling strength, it can be concluded that the wear coefficient of the coated sample is quite large. Under the impact of amplitude loads applied during 5 × 10⁶ loading cycles with a high degree of wear equal to 1.5, the sample showed high safety margins equal to 0.67. The presence of a sprayed layer prevents the concentration of internal stresses in the area of polymer concrete, taking over the resulting stresses under an external force caused by the mechanical properties of the materials, thereby increasing the service life of a manufactured part.

The paper describes an establishment of dynamic characteristics of the newly created passive mechanical system for isolation of low-frequency (0.7 Hz–50 Hz) vibrations. The many metrological means are sensitive to mechanical vibrations and acoustic noise of low frequency. Such may appear both outside and inside a building, i.e. may be caused by wind, heating, aeration, air conditioning equipment, moving vehicles and other. In the paper, description of the theoretical and experimental tests is provided. The obtained dynamic characteristics (transmissibilities) of the passive mechanical low-frequency vibration isolation system show that such a system is able to isolate vibrations effectively in the frequency range of 0.7 Hz–50 Hz. The results of the experimental tests support the results of the theoretical research.