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Effect of the dry hopping of the stability of beer foam
Benda, David ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deals with the influence of dry hopping on the stability of the beer foam. It was observed how this effect affected general characteristics of beer, the content of hop bitter acids, proteins, phenolic compounds, selected micro- and macro elements, organic acids and the stability od the beer foam. Theoretical part characterises raw the materials for beer production, the substances affecting the stability of beer foam and the beer brewing process. Furthermore the beer foam is described froam a physical point of view together with the steps of its formation and drainage as well as other phenomena that lead to its disappearance. A detailed description of used analytical methods is included. The experimental part illustrates the preparation of the model beer and the implementation of dry hopping with the Czech hop variety called Kazbek. Dry hopping was carried out on day 3, day 5 and day 10 with a 3 g/l and a 6 g/l hop dose. The prepared beer was subsequently analysed for general characteristics, the beer foam stability, bitter hop acids, phenolic compounds, protein, selected micro- and macroelements and organic acids. Based on the measured data, there were found correlations between the observed beer parameter and the stablity of the beer foam. The results revealed that dry hopping in beer increases the content of the phenolic compounds and bitter substances, but its effect on the beer foam stability is negative.
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Influence of beer protein on foam stability
Benda, David ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of beer proteins, phenolic compounds, bitterness and selected metal ions on beer foam stability. The theoretical part describes beer foam from the physical aspect, beer foam stability and its measurement and the factors that positively or negatively influences the stability and quality of the beer foam. In the theoretical part are described selected proteins that influence beer foam. In theoretical part is described the origin and technological significance of proteins. The experimental part is dedicated to the measurement of beer foam stability with the NIBEM method, the analysis of total protein content, the analysis of total phenolic content, bitternes and element analysis of beer samples. Measured data indicated correlations between protein content, phenolic compounds content, bitterness and metal ions with the beer foam stability. The results show that proteins and phenolic compounds as isolated parameters don’t essentialy affect the beer foam stability. It was found out, that bitterness as isolated parameter influences the beer foam stability the most.
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Determination of closing valve control moments
Benda, David ; Vosynek, Petr (referee) ; Hnízdil, Milan (advisor)
This bachelor thesis deals with the calculation of the torque on the output shaft of the four-concentric butterfly valves and experimental measurement of this torque on real manufactured valves. At the beginning is carried out a brief research, the purpose describe the basic components of the butterfly valves, its production variants of the offset disc, eventually types of fittings to piping. The main part describes the partial torque occurring on the individual components. Following data from the performer measurement and at the end are compared obtained results.
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Electronic Parts of Small Photovoltaic Power Plant
Benda, Dušan
The aim of this project is to propose a comprehensive system for the management, control and monitoring of individual components of photovoltaic power plants. This article describes the various methods of approaches to solving each described parts including an outline of the issue. The output of work are functional and tested equipment.
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Remote Control for Steam Engines Models
Benda, David
The aim of this project is to create a remote control for radio controlled model of steamboat. The entire device consists of two parts - a transmitter and receiver. Data transmission modules were selected from the company HopeFR communicating in a frequency band of 433 MHz. Currently the device is outfitted for steering a pair of model servo motors and five digital outputs. Simple adjustment facility can be extended as required.
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System of DC/DC converters for solar cells of a fotovoltaic power plant
Benda, Dušan ; Huták, Petr (referee) ; Vorel, Pavel (advisor)
This master thesis describes the design of a DC/DC converter for one photovoltaic panel with a 250 W peak power. The master thesis is divided into parts dealing with detailed design of power electronics, analog circuit design, description of control MPPT algorithms and software for control circuit. The chapter with the mathematical modeling of the converter created in the Matlab Simulink was added beyond the assignment.
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Evolution of host specificity and phylogeography of Strepsiptera parsites of the family Xenidae
Benda, Daniel ; Straka, Jakub (advisor) ; Malenovský, Igor (referee)
The twisted-wing parasites (Strepsiptera) are an endoparasitic order of insects with cosmopolitan distribution, which are sister group of Coleoptera. There are about 600 known species up to date. Strepsiptera parasitize seven insect orders (Thysanura, Orthoptera, Blattodea, Mantodea, Hemiptera, Diptera, Hymenoptera). The family Xenidae is one of the most derived groups of Strepsiptera. Its representatives parasitize aculeate Hymenoptera of three families (Vespidae, Sphecidae, Crabronidae). In comparison to the basal groups, there are well-known hosts for genera of the family Xenidae. Therefore, this group is suitable object for study of the evolution of host specialization. Phylogeny of the family Xenidae was constructed on the basis of molecular analysis of three genes. Moreover, the mapping of ancestral host major groups and biogeographic areas was performed using two methods (parsimony, maximum likelihood). According to the results, the family Xenidae is monophyletic group with Old World origin. There were a several independent switches to the same host groups. This significantly changes the existing ideas about evolution of host specialization and requires a taxonomic revision. Within the family Xenidae, there were several cases of dispersal between the Old World and the New World. Furthermore,...
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Biogeography and host spectrum of twisted-wings (Strepsiptera)
Benda, Daniel ; Straka, Jakub (advisor) ; Malenovský, Igor (referee)
Twisted-wings (Strepsiptera) are an endoparazitic order of insects with cosmopolitan distribution, which are sister group of Coleoptera. There are 7 known host insect orders. As a group with relatively small number of species (almost 600) and cryptic way of life, Strepsiptera were usually overlooked by entomologists. Majority of publications about Strepsiptera deal simply with describtion of new species. For many taxa of basal families, the host group is unknown, because just free flying male has been collected and described. In contrary, only a female collected with host is known in some species. In derived families Xenidae and Stylopidae (parasitize Hymenoptera: Aculeata), there are known hosts in overwhelming majority of species. Many information about distribution of these groups can be extracted also from publications about hosts, where stylopized individuals are mentioned. Presented thesis summarizes the distribution of Strepsiptera at the level of families and genera. It also provides an assessment of the occurrens of Strepsiptera in different biogeographic regions with focus on their hosts. Keywords: Twisted-wings, Strepsiptera, distribution, parasites, host group, biogeography
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