Master's Thesis Abstract Jakub Jungwirth Understanding molecular structure of biochemically relevant molecules is of funda- mental interest for these molecules ultimately determine all functions of living organisms. Raman optical activity (ROA) is a chiroptical spectroscopic technique highly sensitive to molecular structure. This thesis presents an introduction to important concepts of ROA and two independent projects aiming to extend the possibilities of ROA, both from the- oretical and experimental points of view. The first project is a conformational analysis of dialanine, an important model peptide. A combined quantum mechanics / molecu- lar dynamics approach was used in spectral simulations and resulted in spectra with an unprecedented agreement with experiment. To obtain information about conformer equi- libria, a decomposition procedure of an experimental spectrum into calculated individual conformer spectra was coded and tested, and proved to be a viable approach. The sec- ond project was an attempt to carry out pioneering ROA measurements of amyloid fibrils, which are difficult to measure due to their inhomogeneous nature (insolubility, birefrin- gence). Within this project, the preparation protocol for such samples was improved. The performance of an all new rotational cuvette was examined and found...

The aim of this diploma thesis is to describe mechanisms involved in a lubricant film formation in textured conformal contacts. For exploring of the lubricant film formation, the method of optical interferometry is implemented on a pin-on-disc tribometer. That allows to study an influence of a texture on lubricant film thickness and coefficient of friction of textured samples. These samples have different parameters of a texture. On the basis of these effects and the visual image of the contact, the flow of lubricant in the contact area is described. Shallow dimples lead to larger film thickness in elasto-hydrodynamic lubrication regime. They act like a lubricant reservoir. Deep dimples positively affect film thickness in hydrodynamic lubrication regime, where the effect of shallow dimples descend. During experiments, the formation of a cavitation is observed. The cavitation causes a starvation of dimples in many cases. This leads to reducing of the lubricant film thickness. This effect can be eliminated by appropriate parameters of texture in operational conditions of elements.

Tato disertační práce se zabývá tématikou analýzy strukturálních změn ve svalové tkáni a metodikou optického měření. I přesto, že existuje nezanedbatelné množství metod pro detekci konkrétních změn ve svalovině, především pak v konzumním mase, drtivá většina z nich se zaměřuje na jeden konkrétní proces a vyžaduje komplikované postupy a drahé přístroje. Předmětem prezentovaného výzkumu není tedy nalézt metody přesnější a specifičtější, než jsou ty již exitující, ale raději zvolit alternativní přístup k problematice. Součástí je pak i snaha najít možnosti jak obejít technologické nároky moderních postupů a přitom se přiblížit co nejvíce jejich informačnímu přínosu. Za tímto účelem je potřeba mít dostatečné teoretické znalosti a experimentální zkušenosti především v oboru fyziky, optiky a postupů měření, ale také široké povědomí o problematice biologických tkání a procesů v nich probíhajících. Na základě získaných informací a pochopení pochodů ve svalové tkáni jsou navrhnuty a testovány tři rozdílné přístupy. Vytvořené metody pracují s fotony v transmisním i reflexním uspořádání. Pomocí pozorování změn absorpce, rozptylu a polarizace světla po interakci se vzorkem svalové tkáně jsou posouzeny jeho další optické vlastnosti především index lomu a optická anizotropie. Identifikace změn optických vlastností vzorků za různých podmínek umožňuje společně se simulací Monte Carlo posoudit rozdíly mezi vzorky čerstvými, starými, sušenými a jednou či dvakrát zmraženými a rozmraženými.

This thesis deals mainly with perfusion modeling in optical coherence tomography (OCT). The introductory part deals with basic theory of the OCT, including a description of its basic applications. Part of the work was the testing of selected contrasting materials suitable for the OCT and the design and implementation of phantoms, which were subsequently used in the main part of the thesis. In the practical part, attention is paid to the perfusion analysis in the OCT, first the application of the dilution theory in the OCT for flow estimation, then a study testing the basic theory of perfusion on OCT by means of tissue phantom. Another part of the thesis is devoted to the method of speckle variance analysis for flow visualization.

This master thesis deals with the possibility of separation of useful signal from noise using polarization of laser radiation. This thesis is structured into 5 thematic units. The first unit is focused on laser radiation and its properties. The second part contains a deeper focus on the polarization of radiation, its description and the possibilities of measuring the polarization states. The third part of the thesis is devoted to the design of the measuring chains and identification of used elements. Chapter four contains measurement of status of the polarization and its results. The last chapter analyzes particular measuring chains outputs according to their spectral characteristics.

This diploma thesis deals with GPON frame detection system. Partial problems of designing databases, optical networks and management of database system are described in theoretical parts. Practical parts this thesis are focused on design of system for detecting GPON frames and script for analysing of traffic.

The aim of this diploma thesis is to experimentally elucidate the connection between the friction of the specimen with the textured surface and the optical observation of the sliding contact surface. The thesis focuses on the configuration of the journal bearing. This configuration is achieved by replacing the block with a circular sapphire section on a block-on-ring tribometer. For exploring of the lubricant film formation, the method of optical interferometry and fluorescence is implemented on the block-on-ring tribometer. These adjustments allow examination of the effect of the textured surface on the friction coefficient and the thickness of the lubricant film. In a mixed mode, the textures cause a significant increase in friction values and reduce the thickness of the lubricant film. The negative influence of dimples increases with the increasing radial load size. In the hydrodynamic mode, the textures have a lower negative effect on the resulting values than in the mixed mode. The changes are dependent on the size of the radial load and the viscosity of the lubricant. In the hydrodynamic mode, cavitation was not observed, and the effect of the textured surface does not correspond to theoretical prerequisites, which is reflected by lower lubricant thickness and higher friction.

This thesis aims to describe the differences in grease behaviour caused by degradation. Observation of EHL contact and its surroundings is done using optical fluorescence, which allows to measure lubricant thickness even if it is discontinuous and air is present. New grease is observed, along with samples aged in bearings. One sample was worked for 1000 hours, which was the planned duration of the experiment. Two other samples were stopped prematurely after approx. 900 hours. Several possible age-related factors were examined and strong link between contamination and grease behaviour was found. In observed cases, contamination was identified to be the leading cause of lubricant shortage near EHL contact, which is one of possible bearing failure causes. The results expand existing knowledge about grease lubrication topic, but much further research is needed.

The diploma thesis is focused on design of new laboratory exercises on the topic of gigabit passive optical networks. The theoretical analysis is devoted to acquaintance with basic problematics of PON and analysis of individual PON standards. Special attention, besides GPON, XG-PON and EPON standards, is devoted to security issues in PON. The goal of practical section of the thesis is the design of four laboratory exercises. Two exercises are focused on configuring GPON and XG-PON networks in a console environment with the help of exemplary console commands. The goal of the third exercise is to hook up and configure an EPON network using web configuration interface. The fourth exercise is designed for a realization of DoS attack against a fully functioning laboratory GPON network. The objective is to jam the upstream communication bandwidth with laser transmission causing a desynchronization between active network elements.

Táto práca sa zameriava na analýzu vybraných častí GPON rámca pomocou algoritmov strojového učenia implementovaných pomocou knižnice TensorFlow. Vzhľadom na to, že GPON protokol je definovaný ako sada odporúčaní, implementácia naprieč spoločnosťami sa môže líšiť od navrhnutého protokolu. Preto analýza pomocou zásobníkového automatu nie je dostatočná. Hlavnou myšlienkou je vytvoriť systém modelov za použitia knižnice TensorFlow v Python3, ktoré sú schopné detekovať abnormality v komunikácií. Tieto modely používajú viaceré architektúry neuronových sietí (napr. LSTM, autoencoder) a zameriavajú sa na rôzne typy analýzy. Tento systém sa naučí na vzorovej vzorke dát a upozorní na nájdené odlišnosti v novozachytenej komunikácií. Výstupom systému odhad podobnosti aktuálnej komunikácie v porovnaní so vzorovou komunikáciou.