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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Zpětný ventil / Check valve

Nehybová, Petra January 2019 (has links)
In this Master thesis are mentioned the most used constructions of non-return valves. Further consist of operation principles, fields of application, properties and diffi-culties connected to non-return valves. Motion plug of check valve in liquid is described based on CFD Software simulation.
42

Diagnostika perspektivních elektroizolačních kapalin / Diagnostics of the perspective insulating liquids

Spohner, Milan January 2011 (has links)
This work deals with the classification and diagnosis of electrical insulating liquids. Furthermore, the theoretical part describes the mathematical and physical principles of these liquids. The automated workplace was compiled with development environment VEE Pro for measurement of viskosity and control thermostat medingen and modifiable components for measuring complex permittivity in the frequency range. In the experimental part was carried out measurements of selected material parameters, investigated the effect of difficult conditions and made the mathematical evaluation of physical phenomena.
43

Vlastnosti kapalin na bázi organických esterů / Properties of liquids based on organic esters

Toulová, Jana January 2012 (has links)
This master's thesis deals with the electrical insulation fluids used in electronics industry. The analysis of the current state of research and innovations in modern, biodegradable fluids in terms of their use as diagnostics. It is described by the physical nature of polarization and conductivity mechanisms, which are applied in liquids. It was compiled automated workstation for monitoring components of the complex permittivity over a wide temperature range. In the experimental part we analyzed the behavior of liquids selected alternative based on natural esters when exposed to an alternating electric field at various temperatures. Evaluated results are compared with values for conventional mineral oil.
44

Proces dekomprese v hydraulických systémech tvářecích strojů / The process of decompression in hydraulic systems of forming machines

Havelka, Milan January 2015 (has links)
This thesis consists of two main parts. The first part is a theoretical analysis, or a literary research, it is focused on the physical properties of the fluid, which have direct impact on the decompression. The aim of the second part is to evaluate the measurement of the forging valve and subsequently simulate the issue by means of CFD. The first simulations were performed for the maximal valve stroke and used for the CFD solver setup calibration. The subsequent analyses dealt with possible openings of the valve. In the final chapter the theoretical impact of the liquid compressibility and of the undissolved air is discussed. The results of the thesis can prove useful for the new valve setting in hydraulic circuit or for possible geometry modification.
45

Ukázky řízení pohonu s měničem frekvence Sinamics S120 / Examples of drive control with frequency convertor Sinamics S120

Novák, Michal January 2016 (has links)
In this thesis is described a laboratory process of example of traction control with frequency converter SINAMICS S120. The focus of this thesis is divided into three parts. Modification of the traction to translational motion for transport of the open vessel with liquid. Proposal of the autonomous operation of the traction without connection to other devices such as a personal computer or PLC, including wiring diagram. The simulation of a dynamic movement for transport of the vessel with liquid in the simulation environment MATLAB and implementation using the proposed laboratory traction. Commissioning and activation of each control functions is described step by step.
46

Organicko-anorganické polymerní nanokompozity / Organic-Inorganic Polymer Nanocomposites

Ponyrko, Sergii January 2016 (has links)
The epoxy based polymer is one of the very common polymers, which was used as a host to create new better materials - nanocomposites. This thesis focused on the improvement of the thermomechanical properties of the epoxy thermosets without deteriorating their existing benefits and on further potential application of this knowledge in "smart" systems. The largest part of this work is dedicated to the reinforcement of epoxy thermosets by in situ generated silica and synthesis of organic-inorganic nanocomposites. Borontrifluoride monoethylamine (BF3MEA) was chosen as effective catalyst for the formation of nanosilica in epoxy-amine network matrix under nonaqueous (non-hydrolytic) sol-gel process. We proposed the mechanism of the nonaqueous sol-gel procedure, studied the structure evolution during the nanocomposite formation, and also determined the structure, morphology and thermomechanical properties of the obtained epoxy-silica nanocomposites. Significant attention in this work was given to the application of coupling agent and ionic liquids to improve compatibilization of the organic matrix and the inorganic part. As a result of the nonaqueous sol-gel process optimization by combination of the tetramethoxysilane (TMOS) and the coupling agent glycidyloxypropyltrimethoxysilane (GTMS), the high-Tg and...
47

Setkání témat přírodních věd a teologie při výuce na gymnáziu / Common topics of Science and Theology in high school education

ČANDOVÁ, Jana January 2012 (has links)
In the introduction this thesis classifies different conceptions of the relationship between science and faith. Then, it focuses on common topics of natural science and theology in secondary education. It summarises and reflects the experience of teaching practice and deals with the practical options for Christian issues which the students are usually interested in. The topics are presented in relation to a specific high school curricula and sorted into three parts: Death and dysthanasia, Time and rheology, Deus vere ludens et homo ludens. Some practical examples and recommendation for teaching practice are also mentioned.
48

Studium optoelektrických vlastností tenkých vrstev organických polovodičů na bázi ftalocyaninů / Study of optoelectrical properties of organic semiconductor thin film layers of phtalocyanines

Miklíková, Zdeňka January 2015 (has links)
Diploma thesis is focused on the study of optoelectric properties of thin layers of organic materials based on phthalocyanines, which can be used as an active layer of photovoltaic cells. Especially are studied the properties of the thin active layers of PdPc and PdPc + IL on the glass or ceramic substrates with aluminium contact, which are prepared by material printing here. On the prepared samples were first measured current-voltage characteristics in the dark and in the light and then were measured impedance spectrums in the dark. The received results will be used to improve the properties and structures of photovoltaic cells.
49

Dielektrické vlastnosti kapalných izolantů / Dielectric properties of liquid insulators

Jahn, Michal January 2014 (has links)
This master‘s thesis deals with measurement of liquid dielectric materials (insulators). Above all, it is the different kinds of clean and drinking water, but also transformer oils. There was done theoretical information retrieval about the given topic in this project and on the basis of theory there were realized the relevant measurements of selected properties of liquid dielectric, such as permittivity, capacitance, loss number, conductivity, but also temperature dependence of these parameters. The measurements were realized with the help of product manufactured at the faculty FEKT VUT and with the help of measuring system AGILENT 16452A. The measured results were evaluated, graphically processed and compared.

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