National Repository of Grey Literature 16 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Design of an optomechanical module for laser-induced plasma imaging
Buday, Jakub ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
Laser-Induced Breakdown Spectroscopy (LIBS) is a method of analytical chemistry that provides a qualitative and quantitative analysis of a sample. The ablation process of a sample is fast and dynamic and the change of plasma in time and space is a question of a few microseconds. An examination that provides a good time and space resolution is necessary to understand better the physical processes. For this reason, the goal of this thesis is to design a basic optomechanic construction for this type of experiment. Furthermore, it is important to check the functionality of this design and to use it for a basic comparison between the spectroscopic and imaging data. Also, the time development of plasma will be observed under different experimental conditions. The goal of this thesis, in general, is to prove that the morphology of plasma is as it is described in available related literature.
Design of optomechanical module for chemical mapping using Laser-Induced Breakdown Spectroscopy
Švábíková, Anna ; Samek, Ota (referee) ; Pořízka, Pavel (advisor)
This diploma thesis deals with the design of an optomechanical module for chemical mapping using the Laser-Induced Breakdown Spectroscopy (LIBS) method. The main goal is to develop a module capable of the analysis of zinc spectral lines in the ultraviolet (UV) region. Basic theory of the LIBS method is described in this work, followed by a research focusing on the remote LIBS analysis. Possible optical designs of focusing and collecting optics are presented in this work. Chosen optical designs were then tested. The output of this work is the final optomechanical design of the module.
Processing of tomographic data by principal component analysis method for archaeological applications
Prokop, David ; Žídek, Jan (referee) ; Pořízka, Pavel (advisor)
Rentgenová počítačová tomografie je metoda sloužící ke 3D zobrazování vnitřní struktury objektů. Mikrostruktura objektů ukrývá důležité informace, které mohou být použity k jejich charakterizaci. Tato práce podává spojení mezi datasety získanými pomocí rentgenové počítačové mikrotomografie a oblastí statistického zpracování dat. Výstupem metody, pak bude klasifikace vzorků na základě informací o jejich mikrostruktuře. Z výsledků klasifikace vzorků, pak můžeme vyvodit různé hypotézy týkající se původu vzorků. Tato práce by mimo jiné mohla sloužit jako takový nový vhled do problematiky kombinace dat různého původu, pomocí metod statistické analýzy.
Interconnection of Restricted Boltzmann machine method with statistical physics and its implementation in the processing of spectroscopic data
Vrábel, Jakub ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
Práca sa zaoberá spojeniami medzi štatistickou fyzikou a strojovým učením s dôrazom na základné princípy a ich dôsledky. Ďalej sa venuje obecným vlastnostiam spektroskopických dát a ich zohľadnení pri pokročilom spracovaní dát. Začiatok práce je venovaný odvodeniu partičnej sumy štatistického systému a štúdiu Isingovho modelu pomocou "mean field" prístupu. Následne, popri základnom úvode do strojového učenia, je ukázaná ekvivalencia medzi Isingovým modelom a Hopfieldovou sieťou - modelom strojového učenia. Na konci teoretickej časti je z Hopfieldovej siete odvodený model Restricted Boltzmann Machine (RBM). Vhodnosť použitia RBM na spracovanie spektroskopických dát je diskutovaná a preukázaná na znížení dimenzie týchto dát. Výsledky sú porovnané s bežne používanou Metódou Hlavných Komponent (PCA), spolu so zhodnotením prístupu a možnosťami ďalšieho zlepšovania.
Visualization of spectroscopic data using Principal Component Analysis
Šrenk, David ; Žák, Libor (referee) ; Pořízka, Pavel (advisor)
This diploma thesis deals with using laser-induced breakdown plasma spectroscopy for determining the elemental structure of unknown samples. It was necessary to design an appropriate method to qualify material by laser-induced emission spectrum. Pretreatment of data and using a variety of chemometrics methods had to be done in order to qualify the structure of elements. We achieved a required solution by projecting the data to a new PCA space, creating clusters and computing the Euclidean distance between each cluster. The experiment in the practical part was set to detect an interface of two elements. We created a data file simulating the ablation on the interface. This data set was gradually processed applying a mathematical-chemical-physical view. Several data procedures have been compiled: approximation by Lorenz, Gauss and Voigt function and also a pretreatment method such as the detection of outliers, standardization by several procedures and subsequent use of principal components analysis. A summarization of processes for input data is fully described in the thesis.
Approaches to signal correction and standardization in laser spectroscopy
Schiffer, Štěpán ; Hrdlička, Aleš (referee) ; Pořízka, Pavel (advisor)
The subject of this diploma thesis is the study of a sample position influence on results of an experiment in laser spectroscopy. The aim is to design an appropriate way for standardization of signal obtained at different conditions with the respect to its applicability for stand-off analysis. In the theoretical part of the diploma thesis there are the basics of LIBS method described together with the issues of stand-off experiment and both, basic and advanced approches for the processing and correction of obtained spectra. Also the experiment is designed here, which is used for the analysis of the sample inclination and distance influence on the detected signal. The choice of appropriate ways for the signal correction follows and their applicability and efficiency is then experimentally tested.
Transmission of a high peak power pulsed laser with an optical fiber
Holub, Daniel ; Pořízka, Pavel (referee) ; Novotný, Jan (advisor)
The goal of this bachelor’s thesis is to research and compare possibilities for navigating high peak power laser pulses via optical waveguides. This thesis also includes an experiment to decide whether selected optical fiber is suitable for LIBS method of spectroscopy.
A new concept of a light guide – 2K system
Filip, Vojtěch ; Pořízka, Pavel (referee) ; Novotný, Jan (advisor)
The paper target is design of a conceptual solution of a two-component light-guide with the use of available materials, commonly used for the production of headlamp components, emphasizing the simplicity of the whole solution. The result will be in production of a prototype and the subsequent testing of its functional parameters using standard equipment for the measurement of photometric quantities.
Design of collection optics for in-situ Laser-Induced Breakdown Spectroscopy analysis
Švábíková, Anna ; Novotný, Jan (referee) ; Pořízka, Pavel (advisor)
The subject of this bachleor thesis is an optomechanic design for a remote laser induced breakdown spectrometry (LIBS) apparatus. The aim of the bachleor thesis is a design of focusing and collecting optics due to given parameters. This work presents general theoretical basics of LIBS. However, particular attention is given to the description of LIBS instrumentation. Part of this work is a research on remote LIBS anaylysis, particularly on its instrumentation. In the construction part, several optical designs are presented and thereafter the one with best parameters is chosen. The nal output of this thesis is optimisation of chosen optical desing, followed with a construction design of focusing and collecting optics with enclosed drawing documentation.
Fluorine detection by means of Laser-Induced Breakdown Spectroscopy
Jaworková, Magdalena ; Pořízka, Pavel (referee) ; Prochazka, David (advisor)
This work concerns the Laser Induced Break-down Spectroscopy LIBS and it´s usage in detection of fluorine in specimens. This method and the particular methods of measurements suitable for fluorine detection are analysed in theoretical part. The sensitivity of particular methods such as usage of buffer gases (He), change of ambient pressure, usage of double laser pulse (DP–LIBS) or detection of molecular bands are compared in experimental part.

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