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Buzení synchronního motoru jako komplexní mechatronický systém
Pavelka, Jiří; Gric, Petr
2018 -
Moje disertační práce se zabývá analýzou budících soustav synchronních motorů a jejich možném komplexním využití. V mé disertační práci jsem se zaměřil na možnosti jejího mechatronického využití u pohonů turbokompresorů středních a větších výkonů. V úvodu jsem popsal vize a cíle disertační práce a popsal současný stav problematiky budících souprav synchronních pohonů turbokompresorů. A to v třech technických úrovních. Další oddíl se zabývá technickou analýzou jednotlivých komponentů soustrojí turbokompresorů, a to jak jeho elektrických, tak i mechanických částí. Ve zvláštní navazující kapitole se zabýván technickou analýzou vlastností pohonných motorů turbokompresorů a to cíleně na synchronní stroje, jejich elektrické a mechatronické vlastnosti. V následující kapitole č. 5 analyzuji vlastnosti nového budícího systému PEG xxx/μP7, vyvinutého na základě výše popsaného výzkumu. V závěru popisuji hlavní přínosy této disertační práce a reviduji splnění nastavených vizí a cílů. Za velký přínos této práce považuji aplikační odzkoušení uvedených analýz a výzkumů. Proto v poslední kapitole uvádím výběr nejzajímavějších provozních nasazení navržených budících souprav PEG xxx/ μP7.The dissertation thesis investigates the analysis of synchronous motor excitation systems and their possible complex utilisations. The focus is on the possibilities of mechatronic utilisation of the analysis of medium and large power turbocharger machines. The introduction describes the aims and objectives of the project and explains the current theoretical (and practical solutions) of synchronous drives for turbochargers at three technical levels. The following section, concentrates on the technical analysis of individual components which make up turbocharger sets, including both the electrical and mechanical components. The complementary chapter, examines the properties of propulsion engines for turbocompressors, specifically focussing on synchronous machines and their electrical and mechatronic characteristics. Chapter 5 describes the properties of the new PEG xxx / μP7 Excitation System that has been developed for practical applications utilising theoretical conclusions conducted during this research project. The conclusion evaluates the main benefits of this dissertation thesis and reviews the fulfilment of the aims and objectives set for the project The practical applications from the research and theoretical analysis have the most significant contribution to this thesis, which is why the last chapter includes selected practical uses of the PEG xxx / μP7 excitation sets. Available in digital repository of ČVUT.
Buzení synchronního motoru jako komplexní mechatronický systém

Moje disertační práce se zabývá analýzou budících soustav synchronních motorů a jejich možném komplexním využití. V mé disertační práci jsem se zaměřil na možnosti jejího mechatronického využití u ...

Pavelka, Jiří; Gric, Petr
České vysoké učení technické v Praze, 2018

Study of mechanisms of the Spark Plasma Sintering technique
Bouda, Václav; Chráska, Tomáš; Cinert, Jakub
2018 - English
This Doctoral thesis is written for the purpose of a deeper understanding of the spark plasma sintering processes. The main objective of the work is to deeply evaluate how the change of sintering parameters (length of electric pulse, heating rate and sintering pressure) can affect the material properties of a sintered sample. The sintering process was investigated in detail, especially the reliability of temperature measurement. It was found that the measured temperature is different to the real temperature of the sintered sample, moreover this temperature difference depends on the parameters of sintering and the electrical conductivity of sintered powder. On the base of measured data, the sintering process was optimised and the reproducibility of sintering was investigated. While samples sintered by non-pulsed current showed relatively a good reproducibility, the reproducibility of samples sintered by pulse current was significantly worse. The influence of the sintering parameters were studied on a carefully selected materials with regard to the previous measurement. The mechanical properties of the sintered samples were studied through a measurement of porosity, hardness and flexural strength. The phase composition of samples was characterised by XRD analysis. It was found that the pulsed current has not improved any mechanical properties of the sintered samples and contrarily its usage might result in worsening of mechanical properties of the sintered samples. All measurements in this work provide new knowledge about the Spark Plasma Sintering process and thereby contribute to a better understanding of the spark plasma sintering processes. These results might be well used in a further research.Předložená doktorská práce se zabývá hlubším porozuměním problematiky Spark Plasma Sintering, hlavním cílem práce je vyhodnocení vlivu parametru slinování (jako je například délka elektrického pulzu, rychlost ohřevu nebo sekvence ohřevu a aplikovaného tlaku) na mechanické vlastnosti slinutých vzorků. Proces byl detailně studován, zejména pak přesnost měření procesních teplot. Bylo zjištěno, že se teplota slinovaného prášku a teplota měřená výrazně liší. Tento teplotní rozdíl závisí na parametrech slinování, zejména na rychlosti ohřevu a na elektrické vodivosti slinovaného prášku. Na základě naměřených dat byl slinovací proces zoptimalizován a byla vyhodnocena jeho reprodukovatelnost. Jak ukazují naměřené údaje, při slinování stejnosměrným proudem lze dosáhnout poměrně dobré opakovatelnosti výroby, ovšem při použití pulzního proudu se reprodukovatelnost procesu znatelně zhoršuje. Vliv parametrů slinování byl vyhodnocován na široké řadě prášků a při vyhodnocení byly využity poznatky z předchozích měření, zejména byl brán ohled na reprodukovatelnost procesu slinování. Mechanické vlastnosti, respektive jejich změny byly u jednotlivých vzorků vyhodnocovány pomocí měření pórovitosti, tvrdosti a pevnosti v ohybu. U vzorků bylo dále zkoumáno jejich fázové složení a byla pozorována jejich mikrostruktura. Bylo zjištěno, že slinování pulzním proudem nepřináší oproti slinování stejnosměrným proudem žádné prokazatelné vylepšení materiálových vlastností vzorků, naopak u některých typů materiálů bylo prokázáno jejich zhoršení. Všechna tato měření přináší nový pohled na problematiku Spark Plasma Sintering a do značné části prohlubují současný stav znalostí této metody. Tyto výsledky mohou být využity při dalším výzkumu. Available in digital repository of ČVUT.
Study of mechanisms of the Spark Plasma Sintering technique

This Doctoral thesis is written for the purpose of a deeper understanding of the spark plasma sintering processes. The main objective of the work is to deeply evaluate how the change of sintering ...

Bouda, Václav; Chráska, Tomáš; Cinert, Jakub
České vysoké učení technické v Praze, 2018

PHOTONIC SERVICES FOR NON-STANDARD APPLICATIONS OVER ALL-OPTICAL NETWORKS
Zvánovec, Stanislav; Radil, Jan; Škoda, Pavel
2017 - English
Available in digital repository of ČVUT.
PHOTONIC SERVICES FOR NON-STANDARD APPLICATIONS OVER ALL-OPTICAL NETWORKS

Zvánovec, Stanislav; Radil, Jan; Škoda, Pavel
České vysoké učení technické v Praze, 2017

Supporting Exploratory Testing by Automated Navigation Using the Model of System Under Test
Jelínek, Ivan; Bureš, Miroslav; Frajták, Karel
2017 - English
Exploratory Testing (ET) is software testing technique, which is applicable to software development projects, in which test basis (design documentation) is not available, or at least not complete and consistent enough to allow the creation of e cient test cases. The principle of this technique is simultaneous learning, creation of the test cases and testing of the explored system under test (SUT). The key factor for the e ciency of this technique a documentation of explored tester's path in the SUT and the exercised test cases. When this is not being documented properly, ET loses its potential e ciency. Documentation of the explored paths in the SUT also allows more accurate reports of found defects, together with the possibility of the more systematic creation of the test cases during the exploratory testing process, preventing potential duplicities in executed tests. Created test cases can be used later in the next testing phases (retesting of xed defects or regression testing, for instance). Currently, a large ratio of web applications is usually developed without any or su - cient underlying models. In the most of the cases, this is a consequence of required low development costs and usually short time-to-market in the competitive software development environment. Nevertheless, the model is still implicitly present in the SUT code and with proper techniques, it is possible to reconstruct it from the SUT. Using the browser extension and server application, the framework automatically records selected actions of the exploratory testers in the SUT. Based on this recorded data, a screen- ow based model of the SUT is incrementally created and automatically updated. Based on this model and tester's position in the SUT during the testing process, the framework dynamically creates navigational test cases guiding the testers in the SUT and supports its e cient exploration. The recorded model consists of parts representing SUT pages, forms, input elements of the pages, and action elements as submit buttons and links. Besides that, home page, error pages and transition between SUT pages are de ned. The model constructs are accompanied by technical information and meta{data to support the model construction and generation of navigational test cases. In the test leader role, the tester can also extend the model with additional meta{ data. For example, he can prioritize certain pages or selected actions as a result of a risk analysis of the SUT. Moreover, he can de ne equivalence classes determining the suitable test data for particular inputs (e.g. text boxes in the forms) for the later generation of the navigational test cases. The SUT model is described formally and de ned constructs are used to document the proposal and the experiments verifying the framework functionality and practical e ciency. During the dynamical generation of navigational test cases, several navigational strategies can be selected. These strategies are based on combinations of the inputs like the parts of the SUT previously explored by an individual tester or all testers in the team, priority of the particular pages marked by the test team leader, or complexity of explored page elements. Performed experiments show that Exploratory Testing aided by this automated support is less resource demanding than Exploratory Testing performed manually only. With this support, also larger parts of the SUT were explored by the experiment participants in the de ned time. Also, as defect injection experiments have shown, that the proposed automated support helped the testing teams to detect more inserted software defects than ET performed as a manual process only. In particular, the main contributions of the dissertation thesis are as follows: Design and experimental implementation of automated method, which makes Exploratory Testing process more e cient in terms of spent resources, extent of explored SUT and found defects. Innovative combination of Exploratory Testing, Model{Based Testing and Reverse{ Engineering. De nition of formal model of the underlying system under test, which serves as a basis for the framework functionality. Design of initial navigational strategies, ranking functions, and test data strategies, used in the framework. These strategies are supporting the individual as well as team exploratory testing. Practical applicability of the proposed framework to industrial software development and testing projects. Available in digital repository of ČVUT.
Supporting Exploratory Testing by Automated Navigation Using the Model of System Under Test

Exploratory Testing (ET) is software testing technique, which is applicable to software development projects, in which test basis (design documentation) is not available, or at least not complete ...

Jelínek, Ivan; Bureš, Miroslav; Frajták, Karel
České vysoké učení technické v Praze, 2017

Blood vessel segmentation in the analysis of retinal and diaphragm images
Novák, Daniel; Štěpánková, Olga; Vostatek, Pavel
2017 - English
The segmentation and characterization of structures in medical images represents an important part of the diagnostic and research procedures in medicine. This thesis focuses on the characterization methods in two application fields that make use of two imaging modalities. The first topic is the characterization of the blood vessel structure in the human retina and the second is the characterization of diaphragm movement during breathing. The imaged blood vessel structures are considered important landmarks in both applications. The framework for the retinal image processing and analysis starts with the testing of five publicly available blood vessel segmentation methods for retinal images. The parameters of the methods are optimized on five databases with the ground truth for blood vessels. An approach for predicting the method parameters is proposed based on the optimization results. The parameter prediction approach is then applied to obtain vessel segmentation on a new database and an automatic approach to the blood vessel classification and computation of the arteriovenous ratio is proposed and evaluated on the new database. The framework for the diaphragm image processing and analysis is based on the measurement of diaphragm motion. The motion is characterized by a set of features quantifying the amplitude and frequency of the breathing pattern, as well as a portion of the nonharmonic movements that occur. In addition, a set of static features like the diaphragm slope and height are proposed. Two approaches for the motion measurement are proposed and compared. A statistical evaluation of the proposed features is performed by comparing measurements from people with and without spinal findings. The results from the retinal image processing and analysis revealed the possibility of the successful prediction of the parameters of the blood vessel segmentation methods. The automatic approach for the automatic arteriovenous ratio estimation revealed a stronger association with blood pressure than the manually estimated ratio. The results from the diaphragm image processing and analysis confirmed differences in the position, shape and breathing patterns between the healthy people and people suffering from spinal findings. The blood vessel structure was shown to be a reliable marker for characterizing the diaphragm motion. Available in digital repository of ČVUT.
Blood vessel segmentation in the analysis of retinal and diaphragm images

The segmentation and characterization of structures in medical images represents an important part of the diagnostic and research procedures in medicine. This thesis focuses on the characterization ...

Novák, Daniel; Štěpánková, Olga; Vostatek, Pavel
České vysoké učení technické v Praze, 2017

Ochrana sítí s decentralizovanou výrobou energie
Švec, Jan; Hanuš, Radek; Ehrenberger, Jakub
2017 -
Ochrana sítí s decentralizovanou výrobou energie je v posledních letech stále častěji diskutovaným tématem. Připojením zdroje do distribuční soustavy jsou ovlivněny nejenom podmínky provozní, ale také podmínky poruchové. Stávající koncepce chránění distribučních sítí se tak postupně stávají nepoužitelné a stále více jsou nahrazovány koncepcemi známými ze sítí přenosových. Práce se zabývá nastavením nadproudových směrových ochran s časově závislou inverzní charakteristikou a jejich použitím pro sítě s decentralizovanou výrobou energie. Výhoda tohoto typu ochran spočívá především v jejich jednoduchosti a soběstačnosti v rámci chránění celé sítě. Klíčovým úkolem návrhu nastavení je správná volba koeficientů charakteristik jednotlivých ochran tak, aby byla zaručena jejich správná selektivní reakce v kombinaci s co možná nejrychlejším odpojením postižené části sítě. U klasických radiálních sítí bez decentralizované výroby je možno použít ochran nesměrových a nastavení provést „ručně“. Přidáním decentralizované výroby však výrazně narůstá počet podmínek, které musí nastavení splňovat, ochrany musí být směrové a i pro malé sítě se pak z tohoto úkolu stává značně komplikovaný problém. V rámci práce byla pro tento účel navržena metodika a následně vytvořen algoritmus schopný toto nastavení zprostředkovat. Pro pohodlnější aplikaci algoritmu byl vytvořen program umožňující nejenom automatický návrh, ale také ověření nastavení téměř libovolné síťové konfigurace. V Programu byl proveden návrh nastavení několika testovacích sítí s decentralizovanou výrobou energie a následně proveden rozbor jejich chování při různých změnách vstupních parametrů nastavení. Keywords: ochrana sítě; směrová nadproudová ochrana; decentralizovaná výroba energie; rozptýlená výroba energie; časově závislé inverzní charakteristiky; optimalizace nastavení ochran Available in digital repository of ČVUT.
Ochrana sítí s decentralizovanou výrobou energie

Ochrana sítí s decentralizovanou výrobou energie je v posledních letech stále častěji diskutovaným tématem. Připojením zdroje do distribuční soustavy jsou ovlivněny nejenom podmínky provozní, ale ...

Švec, Jan; Hanuš, Radek; Ehrenberger, Jakub
České vysoké učení technické v Praze, 2017

Visible Light Communications for Indoor Applications
Zvánovec, Stanislav; Chvojka, Petr
2017 - English
The field of visible light communications (VLC) has undergone a rapid development in recent years. The increased utilization of light emitting diodes (LEDs) has opened new possibilities for especially indoor services such as broadband internet connection and po- sitioning. Thus, a research within VLC is the main focus of the thesis and is divided into two main parts. At rst, the multiband carrier-less amplitude and phase (m-CAP) mod- ulation, introducing a newly adopted format for spectrally e cient VLC links, is under investigation using both theoretical and experimental approaches. The recommendations for m-CAP transmitter site design are proposed. Next, the channel modeling of indoor VLC is investigated with emphasis on the dynamically changing environments caused by moving people and non-line of sight (NLOS) propagation and new statistical models are derived. Keywords: channel modeling; multiband carrier-less amplitude and phase; visible light communications Available in digital repository of ČVUT.
Visible Light Communications for Indoor Applications

The field of visible light communications (VLC) has undergone a rapid development in recent years. The increased utilization of light emitting diodes (LEDs) has opened new possibilities for ...

Zvánovec, Stanislav; Chvojka, Petr
České vysoké učení technické v Praze, 2017

Dynamic Reconfiguration of Intrusion Detection Systems
Pevný, Tomáš; Rehák, Martin; Stiborek, Jan
2017 - English
Intrusion detection systems (IDS) used in network security are complex solutions that require precise tuning prior to their deployment. Such tuning, however, is a problem. If done statically, the fixed configuration fails to follow the dynamic trends in the network traffic. On the other hand, configuration which is dynamically optimized using the complete traffic of the monitored network (background traffic) is infeasible due to the lack of ground-truth. To tackle these issues, researchers recently proposed to mix prerecorded static traces of labeled network traffic (i.e. challenges) into the background traffic, where they serve as evaluation data, and the IDS is dynamically adapted with respect to these challenges. This thesis extends the challenge-based approach in two steps. In the first step, we adopt techniques from game theory to model the interactions between IDS (defender) and an attacker to make the adaptation process robust against the rational adversaries. We propose a dynamically-defined two-player single stage game with complex utility function to precisely capture incentives of both attacker and defender. Next, we combine the game definition with the challenge-based principle so we can estimate the parameters of the security game online, use traditional game-theoretical solution concept to solve the game, and immediately reconfigure the IDS accordingly. The experimental evaluation proves that this approach outperforms the trust-based baseline solution and thus allows us to improve the performance of the IDS against rational attacker. However, using fixed database of static challenges for dynamic adaptation of the IDS is still far from optimal as it provides data with only limited variability, and manual updates of the database cannot provide new data fast enough as new trends and techniques used by malware authors emerge literally every day. To solve these problems, we propose to replace legitimate challenges with dynamic simulation of network behavior based on probabilistic generative model. We experimentally verified that the proposed model generates network traffic similar to the traffic of real users. Next, we automate the updating the database of malicious challenges via emulation of malicious behavior with network traffic observed during execution of malware binaries in controlled environment (sandbox). In order to address the lack of labeled malware binaries, we propose novel approach for classification and clustering of unknown binaries based on their interactions with system resources (files, network traffic, mutexes, registry keys and error messages generated by the operating system). Moreover, the proposed model prioritizes the generated clusters to further aid the manual analysis of the threat level required in the definition of the security game. The performance of the classification and clustering of malware binaries is verified on large real-world dataset. Available in digital repository of ČVUT.
Dynamic Reconfiguration of Intrusion Detection Systems

Intrusion detection systems (IDS) used in network security are complex solutions that require precise tuning prior to their deployment. Such tuning, however, is a problem. If done statically, the ...

Pevný, Tomáš; Rehák, Martin; Stiborek, Jan
České vysoké učení technické v Praze, 2017

Coupled Learning and Planning for Active 3D Mapping
Svoboda, Tomáš; Zimmermann, Karel; Petříček, Tomáš
2017 - English
The thesis presents several results in the area of 3D perception, with focus on combining learning and planning in active 3D mapping. Autonomous robots, including those deployed in search and rescue operations or autonomous vehicles, must build and maintain accurate representations of the surroundings to operate e ciently and safely in human environment. These representations, or maps, should encompass both low-level information about geometry of the scene and high-level semantical information, including recognized categories or individual objects. In the rst part we propose a method of 3D object recognition based on matching local invariant features, which is further extended for 3D point cloud registration task and evaluated on challenging real-world datasets. The method builds on a multi-stage feature extraction pipeline composed of sparse keypoint detection to reduce complexity of further stages, establishing local reference frames as a means to achieve invariance with respect to rigid transformations without sacri cing descriptiveness of the underlying 3D shape, and a compact description of the shape based on area-weighted normal projections. For a moderate overlap between the laser scans, the registration method provides a superior registration accuracy compared to state-of-the-art methods including Generalized ICP, 3D Normal-Distribution Transform, Fast Point-Feature Histograms, and 4-Points Congruent Sets. In the second part, two tasks from the area of active 3D mapping are being solved| namely, simultaneous exploration and segmentation with a mobile robot in a search and rescue scenario, and active 3D mapping using a sensor with steerable depth-measuring rays, with applications in autonomous driving. For these tasks, we assume that the localization is provided by an external source. In the simultaneous exploration and segmentation task, we consider a mobile robot exploring an unknown environment along a known path, using a static panoramic sensor providing RGB and depth measurements, and controlling a narrow eld-of-view thermal camera mounted on a pan-tilt unit. The task is to control the sensor along the path to maximize accuracy of segmentation of the surroundings into human body and background categories. Since demanding optimal control does not allow for online replanning, we rather employ the optimal planner o ine to provide guiding trajectories for learning a CNN-based control policy in a guided Q-learning framework. A policy initialization is proposed which takes advantage of a special structure of the task and allows e cient learning of the policy. In the active 3D mapping task, our method simultaneously learns to reconstruct a dense 3D occupancy map from sparse measurements and optimizes the reactive control of depth-measuring rays. We propose a fast prioritized greedy algorithm to solve the control subtask online, which needs to update the cost function in only a small fraction of possible rays in each iteration. An approximation ratio of the algorithm is derived. We experimentally demonstrate, using publicly available KITTI dataset, that accuracy of the 3D improves signi cantly when learning-to-reconstruct is coupled with the optimization of depth measuring rays. Available in digital repository of ČVUT.
Coupled Learning and Planning for Active 3D Mapping

The thesis presents several results in the area of 3D perception, with focus on combining learning and planning in active 3D mapping. Autonomous robots, including those deployed in search and rescue ...

Svoboda, Tomáš; Zimmermann, Karel; Petříček, Tomáš
České vysoké učení technické v Praze, 2017

Virtual Distributed Computing Systems and Their Applications
Janeček, Jan; Fesl, Jan
2017 - English
This dissertation thesis deals with the architecture, benchmarking, optimization and implementation of virtual distributed computing systems. Large distributed systems rep- resenting the performance background of all modern cloud computing architectures have become a very hot topic at present. This dissertation thesis o ers an introduction into modern technologies showing a rapid impact on the system performance. One of them is virtualization technology, whose real e ciency was a standalone part of the research. Large distributed systems consume a huge amount of electric power, therefore their optimization was also discussed. New ideas originated from the research were incorporated into the pro- posal of a new distributed system called Centr aln mozek univerzity (CMU). This system is able to manage and automatically optimize large virtualization infrastructures. It is also accessible to the end-users. This system is currently used in teaching many subjects and became a prototype of an educational system of new generation. In particular, the main contributions of the dissertation thesis are as follows: 1. Methodology, design and implementation of a new software benchmark utility able to measure virtualization e ciency of the distributed architecture. 2. New approach in a possible migration of the entire distributed systems between various data centres. 3. New distributed algorithm for virtual machines consolidation, rapidly reducing the energy consumption. 4. Design, description and implementation of the distributed virtualization system CMU.Diserta cn pr ace se zaob r a architekturami, testov an m, optimalizac a implementac virtu aln ch distribuovan ych syst em u. Rozs ahl e distribuovan e syst emy, kter e stoj v pozad v sech modern ch cloudov ych architektur, jsou v sou casn e dob e skute cn e zhav ym t ematem. Pr ace obsahuje teoretick y uvod do modern ch virtualiza cn ch technologi , kter e rapidn e ovliv nuj v ypo cetn v ykon. Efektivita virtualiza cn ch technologi byla jedn m z kl cov ych t emat vlastn ho v yzkumu. Rozs ahl e v ypo cetn infrastruktury spot rebov avaj obrovsk e mno zstv elektrick e energie, p ri cem z optimalizace spot reby byla dal s m p redm etem v yzkumu. Inovativn my sleny, kter e vznikly ve f azi v yzkumu, byly integrov any do n avrhu a im- plementace nov eho distribuovan eho virtualiza cn ho syst emu, kter y nese n azev Centr aln mozek univerzity (CMU). Tento syst em je schopen pln e automatizovan e spravovat a op- timalizovat distribuovan e infrastruktury pro virtualizaci. Syst em dok a ze zprost redkovat p r stup pro vyu zit sv ych v ypo cetn ch prost redk u koncov ym u zivatel um. Takov ato kon- cepce syst emu je sou casn e prototypem v yukov eho syst emu nov e generace, ve kter em je vyu zita architektura datov ych center pro v yuku univerzitn ch p redm et u. Keywords: virtualization; distributed computing systems; cloud computing; live migration; green computing Available in digital repository of ČVUT.
Virtual Distributed Computing Systems and Their Applications

This dissertation thesis deals with the architecture, benchmarking, optimization and implementation of virtual distributed computing systems. Large distributed systems rep- resenting the performance ...

Janeček, Jan; Fesl, Jan
České vysoké učení technické v Praze, 2017

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