• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 85
  • Tagged with
  • 85
  • 61
  • 21
  • 18
  • 16
  • 15
  • 15
  • 11
  • 11
  • 10
  • 10
  • 9
  • 9
  • 9
  • 9
  • 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.
51

Hodnocení konstrukčních detailů budov z pohledu energetické náročnosti / Construction details of buildings evaluation from energy demand point of view

Císař, Milan January 2018 (has links)
Theoretical part of Diploma thesis deals with issues about thermal bridges and thermal connections in building structures. The Calculating part focused on the family houses with a low heat use. The results of this part are energy and financial evaluations of family house. The last part deals with the using of computer technology in engineering practice. These chapters devote about computer modeling an assembly details of passive house and family house after reconstruction (the dates of family house after reconstruction are compared with the results from experimental measurements). The last section of this Diploma thesis solves dynamic modelling of particular passive house in simulation program called Trnsys.
52

Analýza elektrických vlastností epoxidových pryskyřic s různými plnivy v teplotní a kmitočtové závislosti / Electrical properties analysis of epoxy resins with different fillers in temperature and frequency dependence

Horák, Luděk January 2018 (has links)
Presented master's thesis is focused on studying electroinsulating epoxy resin-based sealings. It describes the chemical composition, production, properties and measuring methods of basic electric quantities of these materials. The aim of the thesis is to compare several sets of samples of composite epoxy resins with different kinds of micro-ground siliceous sand as a filling. The temperature and frequency dependence of relative permittivity, dissipation factor and inner resistivity are measured for given samples.
53

Měření elektrických parametrů vysokonapěťových komponentů pomocí elektronického můstku / Measurement of HV equipments by electronic bridge.

Kumičák, Ivan January 2019 (has links)
The main idea of this thesis is measurements of dielectric materials by using a device Tettex. The thesis is about basic physic properties of dielectric materials. The determination of a dielectric material is considered. The behavior of these materials in electrical fields and reasons, those can have an influence on it, are considered as well. In the text are described measuring methods of chosen parameters of dielectric materials by device Tettex and its functional principles. There are an evaluation of measurements, which were done, and a discussion about achieved results.
54

Dielektrické vlastnosti epoxidových pryskyřic / Dielectric properties of epoxy resins

Matoušová, Klára January 2019 (has links)
This diploma thesis deals with the fundamental properties of epoxide mixtures, as determining of these fundamental properties of epoxide mixtures could in the case of favorable results lead to diminishing the amount of defects in epoxide-embedded instrument transformers. As the influence of effects in the manufacturing process of transformers causing poor quality is very extensit, the biggest emphasis is laid capitally on the influence of the epoxide casting mixture composition. The thesis describes the manufacture technology including used methodics and materials. The compositions of epoxide resins and the mechanisms of their curing. Also, the definitions of fundamental properties of dielectric materials and the description of diagnostic methods used to relative permitivity, dissipation factor and inner resistivity are included. suitable casts of acquired samples were set and dried out within the experimental part, followed by measurement of fundamental electrical properties in temperature and frequency relations. Hereafter a comparison of individual samples and the evaluation of their electrical properties will be carried out.
55

Matematické modely transformátorů a asynchronních motorů / Mathematical models of the transformers and asynchronous machines

Cipín, Radoslav January 2008 (has links)
The fist part of this work is dealt with the construction of the mathematical models of voltage and current transformers. There are created and simulated models of voltage and current transformer with the nonlinear magnetization characteristics. The second part of this work is dealt with equivalent circuit of the induction motor in the form of Gamma-circuit. The speed-torque characteristic and the dependence of stator current on the slip are calculated from this equivalent circuit. The third part of this work is dealt with electromagnetic design of the alternating current machines by the help of a classic way and a new way.
56

Návrh antény s kruhovou polarizací pro kmitočtové pásmo 2,4 GHz / Design of circular polarized antenna for 2.4 GHz

Hase, Michal January 2008 (has links)
In this thesis, I introduce two types of circularly polarized rectangular microstrip antennas at 2.44 GHz. First type has direct fed and the second has two inputs for fed. In first case is used a stub to make the frequency with minimum return loss and equal to the frequency with minimum axial ratio. In second case is use the power splitter to divide the wave in to two lines with phase shift 90° for feeding the patch. In this thesis is described, how to get the best results of Axial Ratio.
57

Nízkošumový zesilovač pro pásmo S / Low-noise S-band amplifier

Potěšil, Dušan January 2008 (has links)
This work deals with design, simulation and realisation of a receiving systém of an S-band front end for satellite communication. The first part of the project is designed the low noise amplifier (LNA) with high associated gain. The basic point of the design is choice of the active device. In the present time are available the ultra low noise transistors based on the GaAs with high mobility electron. The two-stage LNA has been designed with Agilent ATF-55143. It is pseudomorphic HEMTs ,which work in an enhancement mode.These transistor do not require a negative bias voltage and have extremely good typical noise figure. The design includes an interdigital tuned band pass filter between stages. The second part of the project is search another way design circuit. There are designed two LNA with paralel coupled line filter. The first has been applied on a PTFE substrate Duroid 5880 with relative permitivity 2,2 and tg d = 0,009. The substrate FR-4 (r = 4.34) with the thickness 0.06” was used for the realization.
58

Studium vlastností kompozitních materiálů plněných nanočásticemi / Study of electrical properties composites with nanoparticles

Lorenc, Aleš January 2009 (has links)
This work deals with properties of electro insulating varnishes and composite materials. The general aim is to study the influence of nanoparticles on dielectric properties of electro insulating varnishes.
59

Automatický anténní analyzátor / Automatic antenna analyser

Dufek, Ivo January 2010 (has links)
This project is dealing with methods of measuring impedances of the antenna systems in the frequency range from the low frequencies to the very high frequencies. There is a discussion about different methods of measuring impedance and each technique is critically evaluated. In terms of this project is compared few types of the professional antenna analyzers. According to this comparison there was made the concept of my own antenna analyzer. There is a detailed description of the design of this device’s important parts including software equipment. Designed instrument has been built and tested.
60

Dielektrické vlastnosti epoxidové pryskyřice plněné nanočásticemi / Dielectric properties of epoxy with nano particle

Ráček, Tomáš January 2010 (has links)
This diploma thesis is focused on the analysis of basic problematics of dielectrics and nanocomposites. It describes the fabrication of experimental samples of nanocomposites from sealing epoxy resin and nanoparticles of titanium dioxide with various weight filling. Further, the thesis deals with measuring and evaluation of dielectric properties of the samples. It examines the influence of weight filling, temperature and frequency of the electric field on volume resistivity, relative permitivity and loss factor.

Page generated in 0.0386 seconds