Search

Your search keyword '"Krejza, Jan"' showing total 53 results
Start Over Author "Krejza, Jan"
53 results on '"Krejza, Jan"'

51. Kvalifikace postupu svařování hliníkové slitiny AW-5083 H111

Author

Sigmund, Marian, Mrňa, Libor, Krejza, Jan, Sigmund, Marian, Mrňa, Libor, and Krejza, Jan

Abstract

Diplomová práce se zabývá kvalifikací postupu svařování hliníkové slitiny EN AW-5083 H111. Tato hliníková slitina byla použita pro výrobu Venturiho trubice. Proto byla vypracována literární rešerše zabývající se vlastnostmi a použitím hliníku a jeho slitin. Další kapitola práce pojednává o svařitelnosti hliníku, hliníkových slitin a o svařitelnosti slitiny EN AW-5083. Část práce je věnována použité metodě TIG a jejím specifikům při svařování hliníkových materiálů. Praktická část diplomové práce se zabývá vlastní kvalifikací svařovacích postupů dle příslušné normy a vyhodnocením podmínek výroby dle výrobkové normy. Poslední kapitola pojednává o celkovém výrobním postupu Venturiho trubice., The diploma thesis deals with the qualification of welding process of aluminum alloy EN AW-5083 H111. This aluminum alloy was used to make a Venturi tube. Therefore, a literature review has been developed dealing with the properties and use of aluminum and its alloys. The next chapter deals with the weldability of aluminum, aluminum alloys and the weldability of EN AW-5083 alloy. Part of the work is devoted to the used TIG method and its specifics when welding aluminum materials. The practical part of the thesis deals with the actual qualification of welding procedures according to the relevant standard and evaluation of production conditions according to the product standard. The last chapter deals with the overall manufacturing process of the Venturi tube.

52. Kvalifikace postupu svařování hliníkové slitiny AW-5083 H111

Author

Sigmund, Marian, Mrňa, Libor, Krejza, Jan, Sigmund, Marian, Mrňa, Libor, and Krejza, Jan

Abstract

Diplomová práce se zabývá kvalifikací postupu svařování hliníkové slitiny EN AW-5083 H111. Tato hliníková slitina byla použita pro výrobu Venturiho trubice. Proto byla vypracována literární rešerše zabývající se vlastnostmi a použitím hliníku a jeho slitin. Další kapitola práce pojednává o svařitelnosti hliníku, hliníkových slitin a o svařitelnosti slitiny EN AW-5083. Část práce je věnována použité metodě TIG a jejím specifikům při svařování hliníkových materiálů. Praktická část diplomové práce se zabývá vlastní kvalifikací svařovacích postupů dle příslušné normy a vyhodnocením podmínek výroby dle výrobkové normy. Poslední kapitola pojednává o celkovém výrobním postupu Venturiho trubice., The diploma thesis deals with the qualification of welding process of aluminum alloy EN AW-5083 H111. This aluminum alloy was used to make a Venturi tube. Therefore, a literature review has been developed dealing with the properties and use of aluminum and its alloys. The next chapter deals with the weldability of aluminum, aluminum alloys and the weldability of EN AW-5083 alloy. Part of the work is devoted to the used TIG method and its specifics when welding aluminum materials. The practical part of the thesis deals with the actual qualification of welding procedures according to the relevant standard and evaluation of production conditions according to the product standard. The last chapter deals with the overall manufacturing process of the Venturi tube.

53. Increased wood biomass growth is associated with lower wood density in Quercus petraea (Matt.) Liebl. saplings growing under elevated CO2.

Author

Arsić, Janko, Stojanović, Marko, Petrovičová, Lucia, Noyer, Estelle, Milanović, Slobodan, Světlík, Jan, Horáček, Petr, and Krejza, Jan

Subjects
*DURMAST oak, *ATMOSPHERIC carbon dioxide, *BIOMASS, *BIOMASS production, WOOD density
Abstract

Atmospheric carbon dioxide (CO2) has increased substantially since the industrial revolution began, and physiological responses to elevated atmospheric CO2 concentrations reportedly alter the biometry and wood structure of trees. Additionally, soil nutrient availability may play an important role in regulating these responses. Therefore, in this study, we grew 288 two-year-old saplings of sessile oak (Quercus petraea (Matt.) Liebl.) in lamellar glass domes for three years to evaluate the effects of CO2 concentrations and nutrient supply on above- and belowground biomass, wood density, and wood structure. Elevated CO2 increased above- and belowground biomass by 44.3% and 46.9%, respectively. However, under elevated CO2 treatment, sapling wood density was markedly lower (approximately 1.7%), and notably wider growth rings—and larger, more efficient conduits leading to increased hydraulic conductance—were observed. Moreover, despite the vessels being larger in saplings under elevated CO2, the vessels were significantly fewer (p = 0.023). No direct effects of nutrient supply were observed on biomass growth, wood density, or wood structure, except for a notable decrease in specific leaf area. These results suggest that, although fewer and larger conduits may render the xylem more vulnerable to embolism formation under drought conditions, the high growth rate in sessile oak saplings under elevated CO2 is supported by an efficient vascular system and may increase biomass production in this tree species. Nevertheless, the decreased mechanical strength, indicated by low density and xylem vulnerability to drought, may lead to earlier mortality, offsetting the positive effects of elevated CO2 levels in the future. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results