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Precision audio preamplifier for headset measurement
Šimek, Michal ; Balík, Miroslav (referee) ; Hanák, Pavel (advisor)
This thesis deals with microphone and headphone preamplifier for microtelephone and headset. The design shall meet the electrical interface requirements set out in ITU-T Rec. P.381(08/2012). The design includes a voltage converter, microtelephone bias and both a battery and an external power supply. In this work is also described the design of printed circuit board and the solution of a low noise in the whole circuit. The aim of this thesis is to design, built and embed the laboratory fixture into a metal box. Finally, measure the product on an APx525 audio precision analyzer.
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Precision audio preamplifier for headset measurement
Šimek, Michal ; Balík, Miroslav (referee) ; Hanák, Pavel (advisor)
This thesis deals with microphone and headphone preamplifier for microtelephone and headset. The design shall meet the electrical interface requirements set out in ITU-T Rec. P.381(08/2012). The design includes a voltage converter, microtelephone bias and both a battery and an external power supply. In this work is also described the design of printed circuit board and the solution of a low noise in the whole circuit. The aim of this thesis is to design, built and embed the laboratory fixture into a metal box. Finally, measure the product on an APx525 audio precision analyzer.
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Analysis of critical parameters of the batteries for space applications
Šimek, Michal ; Šedina, Martin (referee) ; Kazda, Tomáš (advisor)
This thesis deals with the use of lithium-ion batteries for space applications. Primary and secondary electrochemical sources and their comparison are described in the paper. The main part of this work deals with lithium-ion batteries, their history, properties and used materials, deals with the use of li-ion batteries for space applications in terms of temperature and describes the effects of temperatures on li-ion batteries. At the last chapter deals with a lithium plating and his detection. In the practical part, a methodology for the detection of cast plating is proposed, which I then test on a number of cells, which I measure at various practical workloads.
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Analysis of critical battery parameters for space applications
Šimek, Michal
This thesis deals with the analysis of lithium-ion batteries from the point of view of temperature. The aim is to find out at which temperature and C value the lithium plating process starts in the battery by means of non-destructive methods. This process is undesirable for the functioning of lithium-ion batteries as it causes capacity reduction and cell degradation. In this study, commercial cells from GOMspace were selected as the test batteries. GOMspace will be able to use the results of the research to optimize its devices while avoiding lithium plating, which will increase battery life.
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Tandem Anionic Sigmatropic Rearrangement/Radical Reactions and Their Application Toward the Total Synthesis of Natural Products
Šimek, Michal ; Jahn, Ullrich (advisor) ; Urban, Milan (referee) ; Švenda, Jakub (referee)
The thesis describes the development of unprecedented tandem reactions merging anionic oxy-Cope rearrangement with single-electron transfer oxidation of thus generated metal enolates by ferrocenium hexafluorophosphate. The formed α-carbonyl radicals were utilized in oxygenation reactions by coupling them with persistent radical TEMPO, furnishing rearranged α-aminoxy carbonyl compounds. Suitable reaction conditions and factors influencing the rearrangement aptitudes were determined. The obtained polyfunctional products proved versatile in diversifications by polar reactions producing diverse scaffolds. Furthermore, rearranged α-aminoxy carbonyls with a double bond located in the δ-position of the carbonyl group are applicable in all-carbon 5-endo-trig radical cyclizations governed by the persistent radical effect. Despite the low kinetic rate, this rare cyclization mode furnished a number of substituted cyclopentanes. The reaction scope, including competitive cyclization modes, was studied. The developed methodology was utilized as a key reaction step to synthesize appropriately substituted cyclopentane core in a divergent approach to meroterpenoid fungal metabolites isolated from Ganoderma applanatum. The accomplished synthesis of applanatumols V and W and their epimers enabled the correction of...
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Analysis of critical parameters of the batteries for space applications
Šimek, Michal ; Šedina, Martin (referee) ; Kazda, Tomáš (advisor)
This thesis deals with the use of lithium-ion batteries for space applications. Primary and secondary electrochemical sources and their comparison are described in the paper. The main part of this work deals with lithium-ion batteries, their history, properties and used materials, deals with the use of li-ion batteries for space applications in terms of temperature and describes the effects of temperatures on li-ion batteries. At the last chapter deals with a lithium plating and his detection. In the practical part, a methodology for the detection of cast plating is proposed, which I then test on a number of cells, which I measure at various practical workloads.
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Precision audio preamplifier for headset measurement
Šimek, Michal ; Balík, Miroslav (referee) ; Hanák, Pavel (advisor)
This thesis deals with microphone and headphone preamplifier for microtelephone and headset. The design shall meet the electrical interface requirements set out in ITU-T Rec. P.381(08/2012). The design includes a voltage converter, microtelephone bias and both a battery and an external power supply. In this work is also described the design of printed circuit board and the solution of a low noise in the whole circuit. The aim of this thesis is to design, built and embed the laboratory fixture into a metal box. Finally, measure the product on an APx525 audio precision analyzer.
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