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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

Snímání otisku prstu / Fingerprint scanning

Kubiš, Michal January 2010 (has links)
Fingerprints are the oldest and most used form of biometric identification. A critical step is reliable extract minutiae from the fingerprint images. However fingerprint images are rarely of perfect quality, they may be degraded and corrupted due to natural variations in skin and sensing conditions. Thus, image enhancement techniques are necessary prior to minutiae extraction. This work includes implementation of three techniques for fingerprint image enhancement, minutiae extraction and consturction of fingerprint reading device. Experiments are realized with two sets of fingerprints to evaluate the performance of implemented techniques.
42

Analýza EEG během anestezie / EEG Analysis During Anaesthesia

Hodulíková, Tereza January 2015 (has links)
This master's thesis deals with the method of functional examination of brain electric activity. In the first part is description of central nervous system, method of electroencephalography and possible connections. Furthermor the project involves characteristic of EEG signal and its artifacts. It also includes signal processing and list of symptoms, which will be used for an analysis of the EEG during anesthesia. The second part of thesis involves development of application, which allow viewing and proccesing of EEG signal. In conclusion of thesis is carried out unequal segmentation and statistical processing.
43

Statistická charakteristická funkce a její využití pro zpracování signálu / Statistic Characteristic Function and its Usage for Digital Signal Processing

Mžourek, Zdeněk January 2014 (has links)
Aim of this thesis is provide basic information about characteristic function used in statistic and compare its properties with the Fourier transform used in engineering applications. First part of this thesis is theoretical, there are discussed basic concepts, their properties and mutual relations. The second part is devoted to some possible applications, for example normality testing of data or utilization of the characteristic function in independent component analysis. The first chapter describes the introduction to probability theory for the unification of terminology and mentioned concepts will be used to demonstrate the interesting properties of characteristic function. The second chapter describes the Fourier transform, definition of characteristic function and their comparison. The second part of this text is devoted to applications the empirical characteristic function is analyzed as an estimate of the characteristic function of examined data. As an example of application is describe a simple test of normality. The last part deals with more advanced applications of characteristic function for methods such as independent component analysis.
44

Identifikace parametrů elektroencefalografického snímacího systému / Identification of the parameters of an electroencephalographic recording system

Svozilová, Veronika January 2015 (has links)
Elektroencefalografický záznamový systém slouží k vyšetření mozkové aktivity. Na základě tohoto vyšetření lze stanovit diagnózu některých nemocí, například epilepsie. Účelem této práce bylo zpracování signálu z toho systému a vytvoření modelového signálu, který bude s reálným signálem porovnán. Uměle vytvořený signál vychází z Jansenova matematického modelu, který byl dále implementován v prostředí MATLAB a rozšířen ze základního modelu na komplexnější zahrnující nelinearity a model rozhraní elektroda – elektrolyt. Dále bylo provedeno měření signálů na EEG fantomu a následná identifikace parametrů naměřených signálu. V první fázi byly testovány jednoduché signály. Identifikace parametrů těchto signálů sloužila k validaci daného EEG fantomu. V druhé fázi bylo přistoupeno k testování EEG signálů navržených podle matematického Jansenova modelu. Analýza veškerých signálů zahrnuje mimo jiné časově frekvenční analýzu či ověření platnosti principu superpozice.
45

Stanoveni kavitace na ventilu z poklesu průtočnosti a z vysokofrekvenčních pulsací tlaku. / Cavitation assessment from flow rate drop and high-frequency pressure pulsations.

Šebek, Miloš January 2010 (has links)
Main issue of this master´s thesis deals with high-frequency pulsations caused by cavitating hydraulic components (in this case nozzle and throttle valve). In first measurement on the nozzle was not a high-frequency sensor set in the way, so the evaluation was incorrect. After re-setting of the way was the nozzle measured again and the pulsations were evaluated correct this time. During the last measurement was the sensor located behind the throttle valve, which was with gradual opening and cavitation treatment measured. Resulting dependencies worked out on time dependence. A special mathematical method, Fourier transformation, was used. It transformed pressure amplitudes into frequency dependence. Evaluation of dependecies is the basic step for frequency band assesment, in which the cavitation on particular components happens.
46

Stanovení tuhosti, tlumení a přídavné hmotnosti tenké kapalinové vrstvy v těsnící spáře / Assessment of stiffness, damping and added mass in thin liquid layer in sealing gap

Kohut, Vojtěch January 2012 (has links)
The main purpose of this master’s thesis is to propose the methodology suitable for experimental evaluation of additional mass, stiffness and damping by which a liquid layer in the sealing gap affects the rotor. Sealing gaps are important structural elements of hydrodynamic machines. An appropriate design of a sealing gap including the additional effects determination is an inevitable part of the machine overall dynamic design. The thesis also provides a literature search in the field of rotor dynamics and additional effects of a liquid. The designed experiment aiming to determine additional effects of the liquid is based on rotor dynamics evaluation by means of the radial forces measurement. The experiment results were used to determine dynamic properties of dry and wet rotor of the testing device.
47

Syntéza posloupnosti digitálních obrazů s pohyblivým objektem / Synthesis of digital images sequence with moving object

Čermák, Jan January 2014 (has links)
This master´s thesis deals with methods for synthesis of digital image sequence with moving object. At first, we describe basic concepts from Fourier analysis and statistics that are essential for understanding the issue and afterwards we describe methods for the synthesis that were tested on a series of images of a comet moving on a background of a night sky. Finally, we compare the methods and analyse the outcomes.
48

Automatická segmentace periodického pohybu srdečního svalstva v ultrazvukovém záznamu / Automatic Segmentation of Cardiac Tissue Movement from Ultrasound Record

Munzar, Milan January 2015 (has links)
This thesis describes design and implementation of method, which determines beginning of heart beats in echocardiographic record. Design of this method is built around pyramidal Lucas-Kanade algorithm and fast Fourier transform. This method is implemented in C++ language with OpenCV and FFTW libraries. Analysis of the implementation has shown, that this method is sensitive to anomalies in echocardiographic record. This method is developed as a part of the project for an analysis of echocardiographic records for st. Anna hospital at Brno.
49

Metody analýzy vibračních signálů / Methods of analysis of vibration signals

Russ, David January 2016 (has links)
The main target of this master’s thesis is to focus on methods of analysis of vibration signals in electric machines. To get know the basic principles of the diagnostics methods, is important to clarify origin of the vibration signals and the impact they have. The selected methods were tested practically by measurement on electric machines. Measured data were processed in program LabVIEW. In this thesis were created programs which actually can be aplicated for complete vibrodiagnostics of electric machines in particular induction motors. The basic evaluation of vibration are the RMS value, Crest factor, time course and power spectrum. Results of this thesis are used to demonstrate how quickly and effectively can be vibration signals from electric machines evaluated.
50

Křemíkové sluneční články: experimentální studium a modelování základních materiálových parametrů / Silicon solar cells: methods for experimental study and evaluation of material parameters in advanced structures

Holovský, Jakub January 2012 (has links)
This work concerns with today's challenges of photoelectrical characterization methods in the research and development of thin film silicon solar cells. Relevant results are obtained only when photocurrent spectroscopy and measurement of current-voltage characteristics, are applied on the real structures that can however be multi-layered, multi-junction devices with nanostructured interfaces. Analytical and numerical optical models comprising light scattering are used for analysis of light absorption and for evaluation of optical absorption coefficient of silicon layers in sub-gap region. The slope of absorption edge and residual absorption in mid-gap indicate material disorder and defect density. Based on the investigation of electrical interaction between sub-cells in the dual-junction solar cell we developed new methods of evaluation of photocurrent spectra and current-voltage characteristics individually for each sub-cell with no need to contact them directly. Usability of Fourier Transform Photocurrent Spectroscopy as a robust method for photocurrent spectroscopy of amorphous silicon is thoroughly analyzed here. The issues of frequency dependence are addressed in detail and comparison with photothermal deflection spectroscopy is made.

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