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Comparative survey of pupil's chemistry skills at the grammar schools
Pražienka, Miroslav ; Kloučková, Jitka (referee) ; Šulcová, Renata (advisor)
Miroslav Pražienka Comparative survey of pupil's chemistry skills at the grammar schools Charles University in Prague, Faculty of Science, Department of Teaching and Didaktics of Chemistry Modern pedagogical sciences invoke a new approach to teaching, both in technical equipment and educational methods. In new teachers training, also in lifelong learning, computers (and everything connected with them) and active educational methods are preferred. In my survey, I examined these two statements and confront them with 'classical' teaching method. I prepared didactic tools (presentations, games, tests, advances) and I taught with them. At the end, pupils wrote a test and I evaluated it. The results of my survey do not show superiority in effectiveness of any of the methods, however, the results might be influenced by many factors. The obtained results can not be statistically significat because of a small research sample. Nevertheless, the survey shows that modern technical equipment and active education methods are more attractive for pupils and teachers as well, and they make (not only) chemistry education more interesting and enjoyable.
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Spray Cooling at High Temperatures
Chabičovský, Martin ; Čarnogurská, Mária (referee) ; Hajduk, Daniel (referee) ; Raudenský, Miroslav (advisor)
Spray cooling of hot surfaces is used in the metallurgical industry during continuous casting, hot rolling or heat treatment. The water is sprayed on the cooled surface by the nozzle which transforms the water stream to droplets. The spray cooling of hot surfaces can be characterized as forced convection with the presence of the boiling. This physically complicated process is influenced by many factors, such as impurities and contaminants in the water, water temperature, water flow rate, droplet size, droplet impact velocity, surface temperature, surface roughness or the presence of oxides (scales) on the cooled surface. The dominant factor that affects the heat transfer during the spray cooling is the water impingement density. Other factors have a smaller but also significant effect. This doctoral thesis deals with the influence of the water temperature, surface roughness and the presence of oxides on the intensity of the spray cooling. These factors are investigated by laboratory experiments in which the hot steel surface is spray cooled. Effect of the oxide layer is also investigated by the numerical simulation. The experimental results are theoretically explained and generalized using mathematical methods.
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