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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.
71

Diagnostika vysokonapěťových kondenzátorů pro kaskádní napěťový násobič / Diagnosis of high voltage capacitors for cascade voltage multiplier

Baev, Dmitriy January 2017 (has links)
The main subject of the final thesis is to find a suitable method for measuring the partial discharge (PD) in the dielectric of high-voltage capacitor. In the theoretical part of thesis contains from the mechanisms of origin and the harmful effects of partial discharge at high voltage insulation of capacitor. It describes the global galvanic method of partial discharge measurement, the principle of cascade voltage multiplier, its main components (high-voltage capacitor and diode). Nowadays are presented the possibilities of measuring the quality of capacitors for voltage multipliers. In the experimental part of the diploma thesis is familiar with the diagnostics of high – voltage capacitors by means of laboratory measurements on the electronic bridge and with the help of partial discharge measurement system. It describes the design of a suitable electrode arrangement that eliminates the influence of the corona, which makes it impossible to measure partial discharges and the dissipation factor tg . The thesis analyzes the obtained data from measurements and determines the quality level or the degradation of the measured capacitors. The result of the project should be designed the methodology for finding poor quality capacitors in order to increase the reliability of the voltage multiplier.
72

Měření částečných výbojů u vysokonapěťových kabelů / Partial discharge measurement of middle and high voltage cables

Pelikán, Luděk January 2018 (has links)
The main topic of this work is the analysis of the measurement of partial discharge measurements on high voltage cables. The thesis also deals with other measurements, including the measurement of the loss factor and the voltage retention and breakdown test. Part of the text describes the issue of partial discharge, its measurement by galvanic method and methods of elimination of disturbing influences that affect this method in terms of sensitivity and accuracy of the measured values. Thesis also describes the construction of the cables, their marking and the tests carried out on them. There is also a description of the cable terminals used for measuring, especially water terminals, which are designed for high voltages and which are carried out in the practical part of the thesis. The next part deals with problems prior to the commissioning of water terminals and their preparation for certain tests, including description and evaluation of the results of the measurements.
73

Návrh elektronicky rekonfigurovatelných filtračních struktur s moderními aktivními prvky / Design of electronically reconfigurable filtering structures with modern active elements

Prát, Marek January 2018 (has links)
The aim of master's thesis was design of electronically reconfigurable filters. Adjustability of pole frequency or quality factor is possible. First part of thesis deals with theoretical analysis of filters, their operation modes, design of frequency filters using Signal-Flow graph method and parasitic analysis. The next part describes active elements used in thesis. In a third part, three reconfigurable filters are described and designed and their simulations and parasitic analysis are made. Last part deals with filter design in EAGLE and experimental measurement.
74

QoS v systému UMTS / QoS in UMTS

Kavan, Radovan January 2009 (has links)
This thesis treats of QoS (Quality of Service) in UMTS system. The term quality of service is frequently used, recently, however not only in computer networks, but also more and more in mobile networks also. Present system of 2nd generation (2G) GSM enables only limited exploitation of QoS function. System UMTS is a system of 3rd generation (3G) already and contains quality of service in greater measure which is ensured with number of algorithms and functions. Individual QoS functions enable effective utilization of radio interface, support maintenance of planned coverage and offer high spectral efficiency. Functions that cater to quality of service are called RRM functions (Radio Resource Management). There exist five basic functions in UMTS system that are Admission control (AC), Power control (PC), Load control (LC), Handover control (HC) and Packet scheduler (PS). These functions are responsible for control of network access, control of power, control of network load, control of handover and packet (bit rate) scheduling. Last three functions are usually collectively designated as Congestion control, control of network overload. UMTS layer model, differentiation of services, traffic classes and 3GPP concept are also discussed. In thesis the attention is piad to Admission control algorithm – control of network access – in the uplink direction and to different ways of load (in the cell) modeling. Individual approaches are simulated in MATLAB. A possibility of using algorithm in the real system is discussed in conclusion.
75

Izolační a dielektrické vlastnosti vody / Insulation and dielectric properties of water

Grill, Jiří January 2011 (has links)
This master´s thesis deals about insulation and dielectric properties of water. It describes the structure of water, covalent and hydrogen bonds. It outlines primary chemical and physical properties of water and then it describes parameters of water - dynamic viscosity, conductivity, surface tension, pH and also describes dielectric properties - dielectric loss, loss factor, permittivity, polarization. Part of the work is practical section, which includes measurements of deionized water, destilled water, tap water and shows primary dependence such as dependence loss factor on frequency or relative permittivity on frequency.
76

Miniaturní anténa pro mobilní aplikace / Miniature antenna for mobile applications

Šmarda, Marek January 2013 (has links)
This work deals with the most famous constructions of planar antennas. The work analyses selected methods of connecting planar antennas' charging with the possibility of impedance adaptation. An important part of the work consists of description of techniques for increasing bandwidth and conversely techniques for reducing the dimensions which are important for the design of planar antennas for mobile devices. The antennas were designed by means of theoretical basis and their properties were examined in the electromagnetic field simulator. The selected antenna model was constructed and its parameters were measured experimentally. The matching circuit for the antenna to tune it to different resonant frequencies was designed and constructed.
77

Denní osvětlení prostor světlovody / Daylighting of spaces with light guides

Machová, Petra January 2016 (has links)
This thesis deals with the illuminance space through light guide. It describes it's basic principles, technical features and ways of differentiation between the technologies. The thesis also includes latest methods for evaluation of illumination of space supported by various computer simulations.
78

Elektronicky rekonfigurovatelné kmitočtové filtry / Electronically reconfigurable frequency filters

Gajdoš, Adam January 2016 (has links)
The aim of the thesis was design of reconnection-less and electronically reconfigurable filters of SISO type with non-traditional active elements. Adjustability of bandwidth or quality factor is also required. First part of the thesis deals with theoretical analysis of filters, their operation modes and design of frequency filters using Signal-flow graph method aswell. Last but not least, electronical reconfiguration of transfer function and parasitic analysis was discussed. Another part describes active elements used in the practical part of thesis. Behaviors and design of active elements using existing circuits (e.g. UCC,EL2082) are described and their transformation into the Signal-flow graph form too. In the practical part five reconnection-less and reconfigurable filters of SISO type was designed using SNAP program. Simulations were done using Orcad program with ideal and real simulation models of active elements. Last part deals with filter design in EAGLE and experimental measurement.
79

Tepelně technické vlastnosti rámu okenní výplně a připojovací spáry / Thermal properties of the window frame and the connection joints

Hejný, Lukáš January 2015 (has links)
This thesis deals with the solution problem of fitting a window in the wall, especially for passive houses. It provides options to optimize the window connection joints, improve the thermal transmittance of the window frame, thereby reducing the total heat loss through the window. In the first part of the thesis is a research literature on the windows and heat technical and physical mechanisms. Are described equations and physical processes taking place in the windows and related building structures. This section describes the basic points in history, technical description of windows, etc. and present ways of assembly Installation the window and the influence of the thermal properties of the heat loss. The next part deals with the description of the work and the results obtained in the course of doctoral study. Describes the main objectives of the dissertation thesis, calculations and simulations of temperature fields and the results of the calculated values. Furthermore are described and analyzed measurement data and compared with the calculated values. At the end dissertation thesis are given opportunities to improve the current solution regarding the heat transfer coefficient of the frame, the optimal way of installation fillers windows in the perimeter wall and improve the thermal properties of the connecting joint.
80

Optimalizace světelných podmínek v budovách / Optimisation of light conditions in buildings

Vajkay, František January 2013 (has links)
Building physics as a branch of architecture must ensure an indoor comfort of each user and inhabitant of a building object. This involves, acoustics, indoor thermal conditions and among others also daylighting and artificial lighting of buildings. Light as a particle and an electromagnetic wave, is required by the different aspects of the human organism. It allows the living beings to see, influences skin and bones, the biorhythms, etc. Therefore, it is necessary for the engineering community to predict the correct illuminance and luminance levels acting insides. The thesis deals with such issues. More precisely, it assesses the quality of design tools and methodologies, either against CIE reference cases described in CIE 171/2006 and against real measurements done over the working plane of an indoor space located in the attic of Building D of the Institute of Building Structures, Faculty of Civil Engineering, Brno University of Technology, too. The tools tested throughout the solution of the dissertation did involve three computer programs: RADIANCE, WDLS v3.1 and WDLS v4.1, and one numerographical approach, namely the Daniljuk’s innovated methodology (sometimes even combined with the theories of BRS). In addition several software’s have had been created alongside the process assessment, just to mention the “RADIANCE Script”, “RADIANCE Data Evaluation Script” or “MuuLUX“. The later was written as a communication software allowing the connection of the KONICA-MINOLTA T10 illuminance meter to a computer with the aim of data collection while long term observation. The solution did also require the establishment of a measuring element for the determination of the light reflectance values of surfaces. The solutions, results and conclusions do describe how well did the design approaches deal while predicting the resulting awaited daylight factor levels in points over the working plane.

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