National Repository of Grey Literature 5 records found  Search took 0.01 seconds. 
Kinetics of non-isothermal crystallization of polylactide with selected agents
Červený, Ľuboš ; Tocháček, Jiří (referee) ; Bálková, Radka (advisor)
The aim of submitted diploma thesis is the study of non-isothermal crystallization kinetics of polylactide (PLA) with selected agents (1 %) and observation of the emerging crystalline structure under polarizing optical microscope. The agents were talc, a mixture of organic salts with the addition of amorphous SiO2 (HPN 68L) and zinc stearate (HPN 20E) and LAK-301 (potassium salt of 5-dimethylsulfoisophtalate), which is a nucleating agent developer for PLA. The PLA matrix served as a reference. Non-isothermal crystallization took place on a differential scanning calorimeter at cooling rates () 0,3; 0,5; 0,7; 1; 1,5; 2 °C/min After non-isothermal crystallization, the crystalline fraction (Xc) od PLA was evaluated from X-ray diffraction analysis, and the supramolecular structure was observed after chemical degradative etching using confocal laser scanning microscope. The crystallization kinetics were evaluated by the methods of Jeziorny and Mo and the activation energy of the crystallization was determined according to the Friedmann method. All prepared materials were amorphous (Xc 40 % for up to 1,5 °C/min). However, for LAK-301, Xc decreased to 30 % already at the = 2 °C/min and it can be assumed that with increasing its nucleation activity will decrease. A spherulitic structure was observed in all samples, but the number and size of spherulites decreased with increasing and the appearance varied according to the type of agent. Both kinetic models proved to be unsuitable for materials with low Xc and the highest because the rate of crystallization did not change. With the Jeziorny method, it was possible to evaluate the kinetics only for the relative crystallinity Xt = 29–50 % and with the Mo method it was not possible to evaluate the data for the highest for PLA matrix and sample with HPN 68L. The samples with LAK-301 and HPN 68L showed the lowest activation energy.
Magnetic classification of fly ashes and application of products
Červený, Ľuboš ; Švec, Jiří (referee) ; Šoukal, František (advisor)
Submitted bachelor thesis is dealing with problematics of magnetic separation of fly ash and utilization of the products of the separation in production of refractory ceramic materials. High temperature fly ash from power station Mělník was used in this thesis.Thesis evaluates results of magnetic separation at different setting of magnetic separator. It proves, that fraction of particles rich in iron as well as fraction depleted by this iron can be obtained by magnetic separation. In this thesis are presented results of volumetric weight, mineralogic element composition, measurments by heating microscope and results of particle size distribution of unseparated fly ash, but also its both separates. The thesis is focusing on possibilities of utilization as additive in refractory ceramic materials and comparison of their refractory properties. It evaluates results of characterisation of the products using XRD analysis and scanning electron microscopy.
Economic factors and profitabilty in woodworking industry
Červený, Luboš ; Kupčák, Václav (advisor) ; Palátová, Petra (referee)
The diploma thesis was focused on identification of economic factors in the lumber factory and their influences on economic efficiency and competitiveness under real company conditions. The other aim was in the field of the economic viability of forestry and lumber sector. The sawmill Javořice, Inc. became the selected company because of its komplex history. The sawmill was analyzed by financial indicators for period 2003 - 2014. The axis was divided in three time frames, of that two periods are evaluated (1/2 - 2003 - 2006; 2/2 - 2011 - 2016). The second step gives a defines the current competitive environment, for the identification SWOT analysis and 5F were used. Results of thesis contribute to the issue of the economic viability of forestry and lumber sector in the Czech Republic. The impoving trend of financial stability with the deleveraging of the fianancial situation, which is a residue of the insolvency period, follow from the economic analysis of the sawmill Javořice, Inc. In the field of competition the situation in the company is relatively good. The thesis can be a valuable tool, with which everyone can evaluate the company and a partner with who can trade.
Application of project management in construction recreational wooden buildings
Matiáš, Jan ; Riedl, Marcel (advisor) ; Červený, Luboš (referee)
Thesis discusses the use of project management in practice. Practice in this sense, considering the timber and construction, or a combination of both. Construction of the playground, consisting mainly of wooden parts, is described as a project. In the beginning there are defined important concepts to understand the problems and outline general principles and rules for creating a project. In the practical part through decomposition of each activity gets a list of elements on which the process is demonstrated. Important part of the work is the chapter with a detailed description and timetable of activities. Scheduling methods CPM and PERT, these individual steps graphical map. In the discussion they mentioned the possibility of using the project management and the software support. Conclusion The thesis discusses the advantages and disadvantages of the use of project management for small entities dealing with the implementation of similar buildings.
Application of project management in construction of wooden building
Mareš, Vít ; Riedl, Marcel (advisor) ; Červený, Luboš (referee)
In my thesis, I applied project management in optimizing activities in the implementation of wooden buildings. I used methods of PERT and CPM, and then compared their contribution to practical use in the implementation of the historic wooden buildings of baroque truss. I suggested classification methodology sorting random effects in the implementation of timber, which will be useful in the practice of project management. Then I confronted estimates project duration calculated according to these methods with real historical truss during construction.

See also: similar author names
2 Červený, Ladislav
3 Červený, Lukáš
5 Červený, Ľuboš
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