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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.
141

NÁVRH NDT METODY PRO HODNOCENÍ DRÁTKOBETONU / DESIGN OF NON-DESTRUCTIVE METHOD FOR TESTING OF STEEL FIBER REINFORCED CONCRETE

Komárková, Tereza January 2019 (has links)
The doctoral thesis deals with a non-destructive testing method (NDT) designed to evaluate the uniformity of distribution and determination of the concentration of steel fibres in steel fiber reinforced concrete (SFRC). At present, no non-destructive method is available in the field of diagnostics of building structures to assess the concentration and the homogeneity of SFRC. The Institute of Building Testing (SZK FAST BUT Brno) has several diagnostic devices, but their utility for the evaluation of selected parameters of SFRC has not proven during the research activity. This knowledge led to the design of a new measuring instrument in cooperation with the Institute of Theoretical and Experimental Electrical Engineering of the Faculty of Electrical Engineering and Communication (UTEE FEKT BUT in Brno) and the methodology for evaluation of these parameters. The proposed NDT method has been experimentally tested and verified for its utility for the evaluation of SFRC in building practice.
142

Vliv vybraných povrchově aktivních látek na čas do porušení vysokohustotního polyetylénu metodou napěťového krípu v korozivním prostředí / The influence of detergents on time to failure of high density polyethylene by full notch creep test performed in corrosive bath

Kotoučková, Simona January 2021 (has links)
The thesis deals with the study of the influence of concentration and different types of surfactants (Igepal CO-520, Arkopal N110, Igepal CO-890, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, dodecyltrimethylammonium bromide and Dehyton PL) on the environmental stress cracking resistance of high-density polyethylene by means of Full Notch Creep Test. Furthermore, the influence of ligamental stress (3,5; 4,0 a 4,5 MPa), pH of the prepared active environment and type of the water used as a solvent for the surfactants on the time to failure was monitored. An accelerating effect was observed at increased concentration, stress and molecular weight. Faster failure was achieved after exposure to ionic types compared to nonionic. The rate of the notch opening was determined. The brittle and ductile behavior during the process of failure was evaluated by microscopic analysis of the morphology of the fracture surfaces. Based on the pH change after the test, the stability of the active environment was evaluated. Deteriorating quality of surfactant solutions was observed. Raman spectroscopy and Fourier transform infrared spectroscopy were used to detect the surfactant on the surface of the test specimen after the test.
143

Účinek zvýšené koncentrace oxidu uhličitého na množství a aktivitu enzymu Rubisco / Impact of elevated carbon dioxide concentration on the Rubisco amount and activity.

Zachová, Lucie January 2008 (has links)
In this diploma work changes of initial and total activities and content of Rubisco in beech and Norway spruce were studied. The plants were cultivated in conditions with ambient CO2 concentration (350 mol·mol–1) and elevated CO2 concentration (700 mol·mol–1). Three series of samples (at the beginning, in the middle and at the end of growing season) were taken. Initial and total Rubisco activities were measured spectrophotometrically and activation state was calculated. Rubisco content was determined by SDS–PAGE method. Rubisco activity in beech cultivated in elevated CO2 concentration decreased during the whole growing season while in beech growing in ambient CO2 concentration Rubisco activity decreased up to middle of growing season and then increased. Rubisco content in beech in ambient CO2 concentration slightly increased and in beech in elevated CO2 concentration decreased up to middle of growing season and then increased. Rubisco activities in Norway spruce both in ambient and elevated CO2 concentration decreased. Rubisco content in Norway spruce in ambient CO2 concentration decreased but in Norway spruce in elevated CO2 concentration first decreased and then increased.
144

Měření koncentrace atomárního dusíku v dohasínajícím dusíkovém plazmatu / Measure of atomic nitrogen concentration in the nitrogen post-discharge

Josiek, Stanislav January 2014 (has links)
Clean post-discharge nitrogen plasma and nitrogen plasma with different traces have been focus of scientists for more than 50 years and there were published many articles on theme active discharge, post-discharge, processes and reactions. It is possible to create kinetic models from all these information and then calculate concentrations of elements in atomic form. This diploma thesis is focused on measuring of concentration of atomic nitrogen for different conditions (decay time, pressure, admixture). The titration method by nitric oxide in post-discharge was used to determinate of concentration of atomic nitrogen. All experimental results were obtained by the optical emission spectroscopy. Optical emission spectra were taken in the range of 300-600 nm. DC discharge was created in a quartz tube in a flowing regime. The flowing regime was chosen for this experiment because of better time resolution of decay time, order in milliseconds. Decay time was in the range of 16 – 82 ms for individual experiments. Nitrogen flow was 400 mln/min. Nitrogen oxide flow was in the range of 0-10 mln/min and it was added at the selected post-discharge time. Trace of methane was 0,006 % of the whole volume. Total gas pressure was set on values from 500 to 4000 Pa. The output of discharge was set on constant value of current 150 mA and the output has changed according to the amount of pressure. Nitrogen first positive, second positive and first negative spectral systems, NO spectral system and NO2* spectral system were recognized in all measured spectra. Absolute concentration of atomic nitrogen was specified by the method of titration of NO. Traces of methane increase dissociation of molecular nitrogen and therefore increase the concentration of atomic nitrogen. This thesis brings new results into longtime research of moon Titan and new results into study of processes in nitrogen-methane plasma.
145

Efektivnost provozu fotovoltaických generátorů / Operational efficiency of photovoltaic generators

Koval, Filip January 2008 (has links)
Objective of master’s thesis theoretical part is especially to illustrate influence of operation conditions, such as solar radiation, temperature or pollution of photovoltaic generator active area, on load and power characteristics of photovoltaic generator, or more precisely on photovoltaic conversion efficiency. Possible variants of increasing effectivity of using photovoltaic generator are explored, such as solar radiation concentration, photovoltaic generator active area cooling or aplication of optimalization circuit. Pivotal part of master‘s thesis is focused on experimental device practical realisation, concretely type MSQ36-10 photovoltaic generator with oriented concentrators of solar radiation. Practical realisation includes design of master‘s thesis experimental part construction with subsequent design of photovoltaic generator motion cycle necessary for adequate simulation of configuration variants solved using single testing photovoltaic generator. Description of own experimental device construction with list of measuring places used in task takes up. It is used automatic monitoring system working as independent measurement task for required values measuring and consecutive data collecting. It is done in two phases. First phase is measurement of all required values, in second phase measurement with attached optimalization circuit is made. Optimalization circuit sets best working point of photovoltaic generator according to actual working conditions. Master‘s thesis intention is experimental verification of solar radiation concentrators application convenience, orientation of photovoltaic generator or its mutual combination, namely using type MSQ36-10 photovoltaic generator. Objective is evaluation of reached energetic gain for all experimental device layouts in variable operating conditions.
146

Termoelektrický solární generátor / Thermo-electric solar generator

Kočvárek, Ondřej January 2008 (has links)
The introduction of this work is devoted to the description of physical principals and condtruction of modern semiconductor thermoelectric transformers. This work describes thein basic characters and the most commonly used materials for thein production. Further, it mentions the basic principals and physical effects that describe the thermoelectric conversion of energy and the nondestructive method for establishing the basic material characteristics of thermoelectric transformers. The substantiv part of this work is the measuring of the material’s characteristics of the accessible thermoelectric elements through the medium of experimental measuring network. The optimal construction of thermoelectric solar generators used for individual thermoelectric elements are designed based on the taken measurements and the evaluation of material’s characteristics of the observed thermoelectric elements.
147

Měření iontových polí / Ion fields measurement

Svozil, Radek January 2009 (has links)
The aim of this semester project is the introduction to the problematic of ion fields, where and under what circumstances they originate and extinct and the techniques of measurement. The project will deal with the atmosphere and the electrical field of the Earth. I will consider the composition of the atmosphere and the principles of origin and extinction of ions. I am going to mention the division of ions and their influence on the living organisms. Another topic to be dealt with is the methods for measuring the air ions and the small currents. Gradually we are going to learn the known methods of the measuring of air ions. We are going to get a closer look at the method of measuring with the cylindrical aspiration capacitor. We are also going to deal with the problem of measuring very low currents, where they originate and how it is possible to compensate them. The outcome of the project should be the concept and later the creation of the sonde for the measuring of the ion fields itself.
148

Zařízení pro měření koncentrace intracelulárního vápníku v LabVIEW / System for measurement of concentration of intracellular calcium in LabVIEW

Kormanovskaya, Elena January 2014 (has links)
The master’s thesis deals with the methods and system for measurement of concentration of intracellular calcium in LabVIEW. The thesis included theoretical and practical parts. The thesis covers the theory of fluorescence principles, fluorescence methods and indicators for measurement of concentration of intracellular calcium. The procedure of measurement by means of fluorescence microscope, camera and indicators is also mentioned. Literary solution is presented. Block diagram of system for measurement of concentration of intracellular calcium at a graphical programming environment LabVIEW is presented in practical part of master’s thesis.
149

Zařízení pro měření koncentrace intracelulárního vápníku v LabVIEW / System for measurement of concentration of intracellular calcium in LabVIEW

Pochlopeň, Timotej January 2014 (has links)
Master‘s thesis deals with the methods and system for measurement of concentration of intracellular calcium in LabVIEW. The thesis covers the theory of fluorescence principles, fluorescence methods and indicators for measurement of concentration of intracellular calcium. The procedure of measurement by means of fluorescence microscope, camera and indicators is also mentioned. The theory dealing with confocal microscopy is presented and two techniques are compared. Literary solution is presented. The practical part describes the program with a graphical user interface used for acquisition and analysis of data measuring dynamics of intracellular calcium concentration. The experimental part describes the preparation and measurement of cells and evaluation of experiments.
150

Energetické hodnocení obecní budovy / Energy assessment of building of municipality

Janíková, Hana January 2013 (has links)
The main objective of the master’s thesis is elaboration of energy audit within the theme of energy rating of buildings. Work consists of the beginning to the given theme including the actual legislative regulations. Another part is elaboration of the energy audit of building municipality with design and rating the measures of reduction of energy consumptions. In experimental part work deals with evaluation of building thermal envelope with use of thermograph measurement, also with quality of indoor environment within the use of building by measurement of concentration of CO2 and with heat and humidity balance.

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