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The Adjustment of the Tundish Water Model of Continuous Casting

Blaško Peter, Bulko Branislav, Petrík Jozef, Demeter Peter, Socha Vladimir, Hanáková Lenka, Palfy Pavol, Solc Marek, Vasilňáková Andrea

Archives of Metallurgy and Materials

2022

Vol. 67, iss. 1

97--104

Whereas approximately 96.3% of the steel produced worldwide is made by continuous casting, great emphasis is put on the superior efficiency of this process. The water model of the tundish and mathematical modeling is often used for the simulation of the steel flow during continuous casting. The experiments were performed on a model of the tundish with two outlets, at two casting speeds (0.8 m.s-1 and 1.2 m.s-1). Eight setups of the tundish were evaluated, which differed in the design of the dams (with or without drainage holes), in their distance from the center of the tundish, and their height. The contribution of the work is the analysis of phenomena in the tundish water model in conditions of repeatability (ten repetitions). The goal is to find the setup providing the most symmetrical flow, with the minimum difference in the residence times Δτ on the two outlets. Taking into account the results obtained at both casting speeds, the most preferred is setup 2 with the 87 mm high dams placed 587 mm from the center of tundish (Δτ = 0.5). The setup 3 (Δτ = 8.25) appears to be the least appropriate. The higher the casting speed, the higher the number of unsuitable arrangements.

Impact of pilots’ tiredness on the outcome of psychological testing

Socha Vladimir, Hanakova Lenka, Freigang Michal, Kraus Jakub, Stojic Slobodan, Socha Lubos, Hanak Peter

Transport Problems

2019

T. 14, z. 2

55--67

Presented work is primarily oriented on the experimental verification of the influence of fatigue on the psychological condition of the flying personnel, using psychological and performance tests. For the evaluation of a pilot performance, the 24 hours experiment was conducted. In total, eight subjects participated in the experimental measurements. Eight participants went through several tests, including simulator flights, to investigate the effects of the fatigue on the results of psychological measurements. Measurements included workload evaluation, using NASA task load evaluation concept and performance testing, using the so-called OR-test. Significant statistical differences between measurements performed during 24 hours were not found in the case of NASA task load Scores. In the case of OR-test, Friedman ANOVA and subsequent post-hoc analysis show that the greatest decrease in performance was observed in approximately 22 hours of wakefulness, i.e. approximately in half of the measuring process. The concept of 24-hour measurements for the quantification of fatigue is not commonly used yet as well as objectivization using performance testing. As the apparent effect of fatigue is mainly on performance testing results, it can be argued that this work could serve as a basis for further studies on fatigue. Also, it could serve as a support for introducing new pilots' psychological testing procedures in the future, which could contribute to current efforts to improve aviation safety.