Ján Kráľ

This paper details the development and characterization of a photocatalytic efficacy test stand that was designed in response to an urgent global requirement for efficient and economically viable methods of pathogen elimination, such as the COVID-19 pandemic. The primary objective was to...

This article discusses special additive technologies, with a particular focus on the innovative binder jetting technology used to create three-dimensional objects. The theoretical part of this article defines the production process–its shortcomings and benefits. Also, the article describes process parameters and individual steps that must be optimally set for the desired result. Further, the article characterizes the most influential factors that are indispensable in the printing process-metallic powder, binder, printing parameters, and finishing operations after the printing itself. The conclusion of the theoretical part deals with various material possibilities when using binder jetting technology. In the practical part of the article, the properties of the material, the chemical composition, and the resulting accuracy of the printed samples will be verified experimentally. The information obtained will subsequently be used to identify an economically advantageous application of binder jetting technology.

The MM Science Journal, published since 2008, is a world respected scientific journal. The journal, published in English, is double peer reviewed and competitive in distributing knowledge among domestic and international academics and professionals. Full texts are available on-line on the journal...

This article deals with a description of pathogens, ways to combat pathogens, and a brief overview of the devices we use to eliminate them. The aim of the article is to describe the photocatalytic efficiency, which will result in the applicati...

Functionalised textiles are produced eighter by surface treatment of textiles and by knitting or weaving of yarns and fibers with surface modification, or additive incorporated by compounding. Photocatalytic activity of oxides used as pigments TiO₂ and ZnO can be utilized to add antimicrobial and self-cleaning properties to polymerbased fibers and yarns. False twist textured polypropylene yarns containing micronized titanium dioxide, zinc oxide and α-ferric oxide, as well as control sample without oxide pigment, were produced by means of compounding, melt spinning and false-twist texturizing. Knitted textiles made of these yarns were subsequently tested for photocatalytic activity, using sodium salicylate as a model pollutant in indoor conditions and a solution of dye Orange II for solar test in aqueous environment and solar irradiation. Although for indoor conditions both TiO₂ and ZnO showed similar level of activity, reducing the half-time for sodium salicylate break-down by 23% and 24% respectively, this reaction may be considered slow for practical application. In contrast, almost 80% of Orange II was broken down in 24 hours on TiO₂ doped textile in experiment with simulated solar irradiation.

Shell Eco-marathon is an international competition to develop a vehicle with the lowest fuel consumption. The Faculty of Mechanical Engineering of the Technical University in Košice has been involved in this competition for 25 years, during which it developed 8 vehicles. For vehicles are important not only low fuel consumption but also high safety. In addition to the low aerodynamic drag of the vehicle, the low weight of the vehicle is important to achieve low fuel consumption. This is achieved by using ultra-light and solid materials in all parts of the vehicle. The latest generation vehicle uses a self-supporting body, which has increased requirements for front and rear stiffness, as discussed in this article.

The paper presents results of a parametric study into energy absorption capability of thin-walled square section columns with redrawn dents, subjected to axial impact compressive load. Thin-walled aluminum tubes with four dents in the corners were under investigation. The varying parameters were the dent’s depth and distance of the dent to the base. The study was performed using Finite Element numerical code. Three crashworthiness indicators were examined: peak crushing force, crash load efficiency and stroke efficiency. The numerical results are shown in load-shortening diagrams, as well as diagrams and maps of crashworthiness indicators. It was found, that the main factor influencing a crushing mode and, subsequently, energy absorption capability, is a dent depth. The dent distance from the base is of less importance. Also a position of a dent, either at the bottom, or at the top base (the load application point) does not influence the crushing behavior significantly. For the deepest dents the relative increase of crash load efficiency (CLE) amounts 25% in comparison with the column without dents.

The motive behind the effort to make virtual prototyping more sophisticated is first of all cost reduction of manufacturing machine design, followed by reduction of lead time for development, prototyping and testing of the pre-manufacturing machine series. This article deals with the analysis of...