LONG–TERM AUTONOMY OF MOBILE ROBOTS IN CHANGING ENVIRONMENTS
Krajník, Tomáš
2018 - English This habilitation thesis presents research that aims to enable long-term deployment of mobile robots in changing environments. The presented approaches encompass methods that ensure robustness of autonomous visual navigation in outdoor environments for prolonged time periods, spatio-temporal representations that explicitly model the environment changes over time, and supporting software modules that enable robust and accurate robot localisation. The main contribution of the thesis is a novel approach that allows to incorporate the notion of time into most stationary environment models used in mobile robotics. This is achieved by representing the uncertainty of the environment states not by fixed probabilities, but by probabilistic functions of time, represented in the frequency domain. The method allows to integrate unlimited numbers of sparse and irregular observations obtained during long-term deployments of mobile robots into memory-efficient models that reflect the persistence and recurrence of environment variations. The frequency-enhanced spatio-temporal models allow to predict the future environment states, which improves the efficiency of mobile robot operation in changing environments. In this thesis, we present a series of articles, which demonstrate that the proposed approach improves mobile robot localization, path and task planning, activity recognition, human-robot interaction and allows for life-long spatio-temporal exploration of perpetually-changing environments. Available in digital repository of ČVUT. LONG–TERM AUTONOMY OF MOBILE ROBOTS IN CHANGING ENVIRONMENTS

This habilitation thesis presents research that aims to enable long-term deployment of mobile robots in changing environments. The presented approaches encompass methods that ensure robustness of ...

Krajník, Tomáš
České vysoké učení technické v Praze, 2018

Challenges and Open Questions of Machine Learning in Computer Security
Pevný, Tomáš
2018 - English This habilitation thesis presents advancements in machine learning for computer security, arising from problems in network intrusion detection and steganography. The thesis put an emphasis on explanation of traits shared by steganalysis, network intrusion detection, and other security domains, which makes these domains different from computer vision, speech recognition, and other fields where machine learning is typically studied. Then, the thesis presents methods developed to at least partially solve the identified problems with an overall goal to make machine learning based intrusion detection system viable. Most of them are general in the sense that they can be used outside intrusion detection and steganalysis on problems with similar constraints. A common feature of all methods is that they are generally simple, yet surprisingly effective. According to large-scale experiments they almost always improve the prior art, which is likely caused by being tailored to security problems and designed for large volumes of data. Specifically, the thesis addresses following problems: anomaly detection with low computational and memory complexity such that efficient processing of large data is possible; multiple-instance anomaly detection improving signal-to-noise ration by classifying larger group of samples; supervised classification of tree-structured data simplifying their encoding in neural networks; clustering of structured data; supervised training with the emphasis on the precision in top p% of returned data; and finally explanation of anomalies to help humans understand the nature of anomaly and speed-up their decision. Many algorithms and method presented in this thesis are deployed in the real intrusion detection system protecting millions of computers around the globe. Available in digital repository of ČVUT. Challenges and Open Questions of Machine Learning in Computer Security

This habilitation thesis presents advancements in machine learning for computer security, arising from problems in network intrusion detection and steganography. The thesis put an emphasis on ...

Pevný, Tomáš
České vysoké učení technické v Praze, 2018

TEXTILE-BASED STRUCTURES IN ELECTRONIC AND COMMUNICATION ENGINEERING
Vojtěch, Lukáš
2017 - English This thesis deals with the search for and formulation of a theoretical approach to modelling the electrical conductivity of woven textiles and the experimental validation of the approach by measurements performed on woven textile samples. Drawing on these results, the thesis goes on to determine the electromagnetic shielding efficiency of nonhomogeneous 3D structures using modified approaches and succeeds in finding a new analytical description of the electromagnetic shielding efficiency of electrically conductive woven textiles. The proposed description applies to selected types of conductive woven textiles. The author’s basic observation is that woven textiles are structurally similar to metallic grids. The proposed modelling method was analytically validated for the different conductivity values of the yarns used; experimental validation was performed as well. This led to the identification of a set of usable conductivity values for yarns, for which these approaches are valid within a given error. In view of the new approaches to modelling the electrical conductivity and electromagnetic shielding efficiency of conductive textiles presented in this thesis, it is believed that these findings will significantly contribute to the body of interdisciplinary research and applications at the boundary between electrical engineering and materials science. The thesis describes the experiments performed and the development of applications of the proposed materials that span various branches of electronics and communications technologies and demonstrate application potential. The example and experiments presented here will certainly help the reader appreciate the scope and application potential of these materials, especially in the context of interdisciplinary cooperation. The thesis is also meant to serve as learning material for students and to be used for teaching purposes and scientific education in general.Tato habilitační práce se věnuje nejprve nalezení a odvození teoretického postupu modelování elektrické vodivosti tkaných textilií. Tento návrh je následně experimentálně ověřen, pomocí měření na vyrobených vzorcích. S využitím těchto výsledků práce pokračuje využitím modifikovaných postupů odvození elektromagnetické stínící účinnosti nehomogenních 3D struktur, kdy se podařilo dospět k novému způsobu analytického popisu elektromagnetické stínící účinnosti elektricky vodivých tkaných textilií. Navržený popis platí pro vybrané typy elektricky vodivých textilií, realizovaných technologií tkaní. Základním využitým pozorováním, je podobnost struktur tkaných textilií a mřížkových struktur na bázi kovových prvků. Navržený postup modelování je analyticky ověřen pro různé hodnoty elektrické vodivosti použitých přízí, zároveň je provedeno i ověření v experimentu. Výsledkem je nalezení oboru hodnot použitelných elektrických vodivostí přízí, pro které tyto postupy platí s danou chybou. Z pohledu v této práci publikovaných nových postupů modelování elektrické vodivosti i elektromagnetické stínící účinnosti elektricky vodivých tkaných textilií, se jedná o soubor nových poznatků, které významně přispívají k rozvoji mezioborových znalostí a aplikací na rozhraní elektrotechniky a materiálového inženýrství. V práci jsou uvedeny také realizované experimenty i výsledky výzkumu a vývoje aplikací navrhovaných typů materiálů, které pokrývají různé oblasti elektroniky a komunikační techniky, s potenciálem jejich užití v praxi. Publikované příklady a experimenty jistě pomohou čtenáři lépe pochopit rozsah a potenciál aplikací těchto materiálů, zejména v kontextu mezioborové spolupráce. Práce si zároveň klade za cíl působit i jako didaktická podpora a umožnit další využití textu pro výukové a vědecké účely. Keywords: Electrically conductive textile; Electrical conductivity; Electromagnetic shielding efficiency; Communication engineering; Interdisciplinary research and application; Elektricky vodivé textilní materiály; Elektrická vodivost; Elektromagnetická stínící účinnost; Komunikační technika; Mezioborový výzkum a aplikace Available in digital repository of ČVUT. TEXTILE-BASED STRUCTURES IN ELECTRONIC AND COMMUNICATION ENGINEERING

This thesis deals with the search for and formulation of a theoretical approach to modelling the electrical conductivity of woven textiles and the experimental validation of the approach by ...

Vojtěch, Lukáš
České vysoké učení technické v Praze, 2017

Energy and Economic Efficiency
Bemš, Július
2017 - English Available in digital repository of ČVUT. Energy and Economic Efficiency

Bemš, Július
České vysoké učení technické v Praze, 2017

Spectroscopy of the optical absorption edge of solar cell materials
Holovský, Jakub
2017 - English The focus of this thesis is relatively narrowly defined as spectroscopy of the optical absorption edge of the actual or potential photovoltaic materials. This includes the spectroscopy methods and interpretation of results, the photovoltaic materials and their technological parameters and also the potential of certain photovoltaic technologies as a renewable source of energy. The materials presented here are either absorbers: amorphous silicon (a-Si:H), microcrystalline silicon, organo-metalhalide perovskites (CH3NH3PbI3) or materials for transparent electrodes: graphene, amorphous InZnO and amorphous ZnSnO. The physical effects studied are related to material preparation methods, ageing, exposure to light, and annealing. The methods employed here for the absorption spectroscopy are photothermal deflection spectroscopy and photocurrent spectroscopy. The two methods are briefly explained and compared. Two main issues related to correct interpretation of these measurements are discussed: effect of surface states and the effects of light scattering. The absorption spectrum in sub-bandgap region is measured to obtain mainly the slope of the absorption edge parametrized by Urbach energy. It is shown here, how theoretically and practically this parameter correlates with the maximum attainable efficiency of solar cell – if the material is used as absorber. If the material is used as transparent electrode, correlation with conductivity is found. The effect of cost evolution in the photovoltaic industry is discussed with the consequence on the efficiency as a most critical parameter dictating the cost of energy. The competitiveness of the solar energy is reviewed for different levels of autonomy. Keywords: solar cells; photovoltaics; photocurrent spectroscopy; photothermal spectroscopy; Urbach energy; sub-bandgap absorption Available in digital repository of ČVUT. Spectroscopy of the optical absorption edge of solar cell materials

The focus of this thesis is relatively narrowly defined as spectroscopy of the optical absorption edge of the actual or potential photovoltaic materials. This includes the spectroscopy methods and ...

Holovský, Jakub
České vysoké učení technické v Praze, 2017

Analysis of Heterogeneous Biomedical Data
Novák, Daniel
2016 - English Available in digital repository of ČVUT. Analysis of Heterogeneous Biomedical Data

Novák, Daniel
České vysoké učení technické v Praze, 2016

Flashover performance investigation of polluted and ice covered insulators exposed to the transient overvoltages
Prochazka, Radek
2015 - English Available in digital repository of ČVUT. Flashover performance investigation of polluted and ice covered insulators exposed to the transient overvoltages

Prochazka, Radek
České vysoké učení technické v Praze, 2015

Habilitační práce
Zimmermann, Karel
2015 - English Available in digital repository of ČVUT. Habilitační práce

Zimmermann, Karel
České vysoké učení technické v Praze, 2015

Geometry of Perspective Cameras – An Algebraic Approach
Pajdla, Tomáš
2015 - Available in digital repository of ČVUT. Geometry of Perspective Cameras – An Algebraic Approach

Pajdla, Tomáš
České vysoké učení technické v Praze, 2015

Praxe. Výzkum. Škola
Tichý, David; Pelčák, Petr; Klokočka, Jiří; Galčanová, Lucie
2015 - Available in digital repository of ČVUT. Praxe. Výzkum. Škola

Tichý, David; Pelčák, Petr; Klokočka, Jiří; Galčanová, Lucie
České vysoké učení technické v Praze, 2015