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Generalized Gram-Schmidt Process: Its Analysis and Use in Preconditioning
Jiří Kopal; školitel Miroslav Tůma
2014 - English
The main goal is to present a new dropping technique that may generally help to better understand of the interplay between floating-point analysis and numerical aspects of preconditioning by incomplete decompositions. Hlavním cílem je prezentovat techniku odvrhování prvků, která může obecně napomoci lepšímu pochopení spojitosti mezi analýzou v aritmetice s konečnou přesností a numerickými aspekty předpodmínění počítaných pomocí neúplných rozkladů.
Keywords:
algoritmy (programování)
Available to registered users in the Library of TUL
Generalized Gram-Schmidt Process: Its Analysis and Use in Preconditioning
The main goal is to present a new dropping technique that may generally help to better understand of the interplay between floating-point analysis and numerical aspects of preconditioning by ...
Nitrogen S-phase Coatings for Food processing Industry
Věra Jahodová; školitel Petr Louda
2014 - English
The aim of this doctoral thesis is deposition of nitrogen doped coatings on austenitic stainless steel to enhance the wear resistance in food processing industry. Wear rate loss was significantly decreased although the values of friction coefficient increased compared to steel substrate. Resistance to general corrosion was not affectedm, better behaviour was observed after immersion tests in physiological solution. Cílem práce bylo vytvoření vrstev dopovaných dusíkem na austenitické korozivzdorné oceli pro zvýšení otěru odolnosti v potravinářském průmyslu. Zkoumání struktury potvrdilo existenci fáze S bez přítomnosti dalších fází (např. nitridy chromu). Tvrdost se zvyšovala se zvyšujícím se obsahem dusíku až třikrát. Opotřebení bylo výrazě sníženo o dva řády, i kdyř koeficient tření vzrostl poroti ocelovému podkladu. Korozní odolnost nebyla narušena a byla pozorována dokonce lepší odolnost po ponoru ve fyziologickém roztoku.
Keywords:
koroze; opotřebení materiálu
Available to registered users in the Library of TUL
Nitrogen S-phase Coatings for Food processing Industry
The aim of this doctoral thesis is deposition of nitrogen doped coatings on austenitic stainless steel to enhance the wear resistance in food processing industry. Wear rate loss was significantly ...
Automatic speech recognition of Vietnamese
Nguyen Thien Chuong; školitel Josef Chaloupka
2014 - English
This thesis presents the work on automatic speech recognition of Vietnamese, a tonal, syllable-based language in which new approaches have to be applied to obtain reliable results. When dealing with Vietnamese, the following basic problems have to be solved or clarified: the selection of phonetic unit to build acoustic models, the collection of text and speech corpora, the creation of pronouncing dictionary, the construction of language model and especially, the methods to deal with tone. With the basic idea of systematically and methodically finding solutions to all the problems mention above, in this work, several methods for collecting large text and speech corpora are first described in which two types of text corpora are obtained by exploiting the source of linguistic data from the Internet, and also two types of speech corpora are extracted, including an Internet-based large continuous speech corpus and a recorded audio-visual speech corpus. Then, a standard phoneme set optimal to Vietnamese with its corresponding grapheme-to-phoneme mapping table is proposed. By constructing various types of pronunciation dictionaries and language models for Vietnamese, the optimal way to integrate tone in a syllable as well as the strategies to deal with speech recognition of Vietnamese will be totally examined in the form of large vocabulary continuous speech recognition tasks. The study is further extended to the field of audio-visual speech recognition of Vietnamese in which the performance gains of audio only speech recognition in noisy condition is proved to be noticeable when integrated with visual information. In this work, many types of visual front ends and visual features are examined in the task of isolated-word speech recognition of Vietnamese. Práce se zabývá zpracování vietnamského jazyka. V rámci práce jsou navrženy, implementovány a otestovány algoritmy pro rozpoznávání spojité řeči s přihlédnutím na specifika vietnamského jazyka. Součástí práce je i kapitola věnovaná audiovizuálnímu rozpoznávání řeči při využití metody AM.
Keywords:
rozpoznávání řeči; vietnamština
Available to registered users in the Library of TUL
Automatic speech recognition of Vietnamese
This thesis presents the work on automatic speech recognition of Vietnamese, a tonal, syllable-based language in which new approaches have to be applied to obtain reliable results. When dealing with ...
Identification and prediction source vibration and noise of disc brake on car
Thai Huynh le hong; školitel Pavel Němeček
2014 - English
The vibration and noise of disc brake system is omong the most important priorities for todayś vehicle manufacturersthat are known as namely brake squeal. Overall brake squeal can be annoying to the driver, vehicle passengers, passers-by, pedestrians. The brake squeal experiment was performed on chassis dynamometer system at TUL with full disc brake system suspension of real car by standard SAE J2521. Furthermore, an analysis of SEM and EDS for pads with different worn were shown that the percentage noise occurrence of pad that high worn is higher than pad with low worn. Simultaneously, it is also explained effecting characteristic of disc and pad surfaces to contribute creating noise. V dnešní době je pro výrobce automobilů jednou z hlavních priorit řešení problematiky hluku a vibrací kotoučových brzd vznikajících při brzdění (často jako skřípění brzd). Takto vzniklé vibrace a hluk snižují komfort posádky vozu a zároveň mohou být velmi nepříjemné pro ostatní účastníky silničního provozu. Experimentální měření bylo provedeno na válcovém dynamometru na Katedře vozidel a motorů TUL K experimentu bylo použito vozidlo určené pro běžný provoz. Experiment byl proveden dle normy SAE J2521. To napomohlo simulaci dosáhnout rozdílných stavů brzdového systému odpovídajících reálným podmínkám.
Keywords:
hluk; vibrace; brzdy
Available to registered users in the Library of TUL
Identification and prediction source vibration and noise of disc brake on car
The vibration and noise of disc brake system is omong the most important priorities for todayś vehicle manufacturersthat are known as namely brake squeal. Overall brake squeal can be annoying to the ...
New Methods in the Study of Roller Electrospinning Mechanism
Fatma Yalcinkaya; školitel Oldřich Jirskák
2014 - English
Needleless roller electrospinning is a new technique when compared with needle electrospinning; therefore, parameters of needleless electrospinning have not yet been fully identified and defined. Some dependent parameters were defined in previous works. Relations between selected independent and selected dependent parameters were studied, as it is shown in theoretical part, both experimentally and theoretically. Not all the parameters were defined and studied yet, such as: spinner geometry, roller properties, roller velocity. Only few dependent parameters were defined (throughput, fiber diameter and diameter distribution, quality of nanofiber layer and some others). Ve srovnání s jehlovým elektrostatickým zvlákňováním je bezjehlové zvlákňování novější technologií; z toho důvodu nebyly dosud parametry bezjehlového zvlákňování v celé šíři identifikovány a definovány. Některé závislé parametry byly definovány v předešlých pracích. teoreticky i experimentálně byly také studovány vztahy mezi vybranými nezávislými a závislými parametry, jak je popsáno v teoretické části práce. Některé parametry však dosud nebyly studovány, jako například: geometrie zvlákňovacího zařízení a vlastnosti a rychlost otáčení válcové zvlákňovací elektrody. Ze závislých parametrů byly definovány pouze některé -zvlákňovací výkon, průměry vláken a jejich distribuce, kvalita nanovlákenné vrstvy.
Keywords:
elektrostatické zvlákňování
Available to registered users in the Library of TUL
New Methods in the Study of Roller Electrospinning Mechanism
Needleless roller electrospinning is a new technique when compared with needle electrospinning; therefore, parameters of needleless electrospinning have not yet been fully identified and defined. Some ...
Experimental and analytical study of thermo-mechani cal properties of composites fabrica ted from geopolymer matrix reinforced woven fabrics
Phan Thanh Nhan; školitel Bohdana Marvalová
2013 - English
Geopolymers are inorganic polymeric materials with a chemical composition similar to zeolites but without defined crystalline structure and possessing ceramic-like features. The disertation will focus on experimental evaluating as well as numerical simulating the thermo-mechanical properties of geopolymer bindes with abbreviated name FC4 combined with commercial woven fabrics such as carbon, glass and basalt. Geopolymery jsou anorganické polymerní materiály s chemickým složením podobným zeolitům bez definované krystalové struktury, které se svým chováním blíží keramice. Práce se zaměřuje na experimentální vyhodnocení, stejně jako numerická simulace termo-mechanické vlastnosti geopolymerního pojiva se zkráceným názvem FC4 v kombinaci s komerčními tkaninami, jako jsou uhlík, sklo a čedič.
Keywords:
kompozitní materiály; mechanické vlastnosti materiálů
Available to registered users in the Library of TUL
Experimental and analytical study of thermo-mechani cal properties of composites fabrica ted from geopolymer matrix reinforced woven fabrics
Geopolymers are inorganic polymeric materials with a chemical composition similar to zeolites but without defined crystalline structure and possessing ceramic-like features. The disertation will focus ...
Renewable Nanoscale Reinforcement of Biodegradable Polymers
Vijaykumar Narayandas Baheti; školitel Jiří Militký
2013 - English
Textile industry generate significant amount of waste fibers in form of short lengths during mechanical processing. However these short fibers possess excellent properties suitable for many other applications. The objective of this work was to use them for the preparation of nanoparticles/nanofibrils, as fillers in biodegradable composite applications such as food packaging, agriculture mulch films, automotive plastics, etc. In the present study, waste jute fibers generated in textile industries, were wet pulverized to the scale of nanofibrils of 50 nm diameter using high energy planetary ball milling for three hours.The rate of refinement of uncleaned jute fibers having non-cellulosic contents was found slower than the cleaned jute fibers. This tendency is attributed to the strong holding of fiber bundles by non-cellulosic contents which offered resistance to the defibrillation during wet milling. In addition, the presence of water during wet pulverization found to reduce the rising temperature of mill, which prevented sticking of nanofibrils on the mill wall and resulted in unimodal size distribution. In the subsequent stage, 1 wt %, 5 wt % and 10 wt % of jute nanofibrils were incorporated in poly lactic acid (PLA) matrix to prepare nanocomposite films by solvent casting. The reinforcement of nanofibrils was investigated from the improvements in mechanical properties based on tensile tests, dynamic mechanical analysis and differential scanning calorimetry. The maximum improvement was observed in case of 5 wt % nanocomposite film where initial modulus and tensile strength increased by 217.30 % and 170.59 % respectively compared to neat PLA film. These improvements are attributed to the increased interaction between nanofibrils and matrix as well as to the increased crystallinity of PLA in composites. The improvements in load bearing capacity of nanocomposite films were significant at 60oC than 35oC, which showed ability of jute nanofibrils to improve the softening temperature of PLA matrix. In the end, experimental results of Initial modulus were compared with predicted modulus of mechanical models. A good level of agreement was observed up to 5 wt % loading of jute nanofibrils.
Keywords:
vlastnosti materiálů; polymery
Available to registered users in the Library of TUL
Renewable Nanoscale Reinforcement of Biodegradable Polymers
Textile industry generate significant amount of waste fibers in form of short lengths during mechanical processing. However these short fibers possess excellent properties suitable for many other ...
Investigation of Aggregation Models of Magnetic, Zero-valent Iron Nanoparticles
Dana Rosická; školitel Jan Šembera
2013 - English
This work focuses on an investigation into the aggregation mechanisms of unstable, nanoscale particles in flowing groundwater. A study and a description of the process of aggregation help to simulate the transport of unstable undissolved nanoparticles. This could be useful when one needs to know how the nanoparticles behave in transit. In the following example a knowledge of this process is helpful. Some contaminants, such as halogenated hydrocarbons, are remediable by zero-valent iron nanoparticles. These are very unstable particles but still have a high potential in remediation field. Thanks to their (nano)size, they can migrate through the ground and are able to decontaminate wide areas. However, they aggregate into microsized entities and lose their migratory ability. Simulation of the transport of iron nanoparticles and their aggregation could be useful in predicting the success of decontamination interventions. The mathematical derivation of iron nanoparticle aggregation is so complex and difficult that this work is focused mainly on them. This work is mainly theoretical. First, an aggregation model is described. The model is based on aggregation due to the heat fluctuation of nanoparticles and due to their different velocities during sedimentation and drifting in groundwater. This model is then extended to include the impact of repulsive electrostatic and attractive magnetic forces that affect the rate of aggregation of magnetic nanoparticles with non-zero surface charge. The coefficients of aggregation are recalculated in order to compute the aggregation not only between single nanoparticles, but also between aggregates of nanoparticles (more simply called "particles"). A study of the possible aggregate structures was performed to be able to compute their mutual reactions. Extended coefficients of aggregation between particles were converted to coefficients of aggregation between ''sections'' of nanoparticles with similar size and properties. This enabled the simulation of aggregation in real time. The subsequent part of this work is dedicated to the computational aspects of aggregation in order to make the computation faster, but with a small error. At the end of the work, simulations of aggregation and transport of different types of nanoparticles are presented.
Keywords:
nanočástice
Available to registered users in the Library of TUL
Investigation of Aggregation Models of Magnetic, Zero-valent Iron Nanoparticles
This work focuses on an investigation into the aggregation mechanisms of unstable, nanoscale particles in flowing groundwater. A study and a description of the process of aggregation help to simulate ...
In-situ polymerization of pyrrole on textile substrates and characterization of their applications
Abdul Malik Rehan Abbasi; školitel Jiří Militký
2013 - English
In this work, PPy coated on E-glass fabric of different densities and EMSE for transmission and reflection was analysed. To the best of my knowledge this is a novel work in its nature for the application of the product as an industrial textile for the shielding of rooms, chambers and electronic devices etc. By taking two fabric densities of glass fabric into account, it was found that EMSE follows power function of surface resistivity of PPy coated highly dense glass fabric (900 g.m-2) and linear function of surface resistivity in case of comparatively low density fabric (410 g.m-2). V této práci byly analyzovýny účinnost stínění (EMSE) pro přenos a odraz za použití E-skelných tkanin různé hustoty potažených polypyrrolem. Dle názoru autora, toto je ve své podstatě nový výzkum pro použití tohoto produktu jako průmyslové textilie pro stínění místností, komor, elektronických zařízení atd. Bylo zjištěno, pokud uvažujeme dvě skelné tkaniny s různou hustotou, že EMSE skelné tkaniny s vysokou hustotou (900g.m-2) potažené polypyrrolem sleduje geometrickou funkci povrchového odporu a že EMSE skelné tkaniny s nízkou hustotou (410g.m-2) potažené polypyrrolem sleduje lineární funkci povrchového odporu.
Keywords:
materiálové inženýrství
Available to registered users in the Library of TUL
In-situ polymerization of pyrrole on textile substrates and characterization of their applications
In this work, PPy coated on E-glass fabric of different densities and EMSE for transmission and reflection was analysed. To the best of my knowledge this is a novel work in its nature for the ...
Řízení statické a dynamické mechanické odezvy piezoelektrických kompozitních skořepin: Využití v akustice a adaptivní optice :
Kateřina Nováková; školitel Pavel Mokrý
2013 - English
This dissertation thesis (Thesis) deals with the study of possibilities to actively control the static and dynamic mechanical response of planar structures by means of attached piezoelectric actuators. The considered planar structures have a form of flat or curved piezoelectric composite shells. It will be shown that such piezoelectric composite shells can provide efficient and rather simple mechatronic systems that can be profitably used in applications to acoustics and adaptive optics.
Keywords:
akustika; adaptivní optika; kompozitní materiály
Available to registered users in the Library of TUL
Řízení statické a dynamické mechanické odezvy piezoelektrických kompozitních skořepin: Využití v akustice a adaptivní optice :
This dissertation thesis (Thesis) deals with the study of possibilities to actively control the static and dynamic mechanical response of planar structures by means of attached piezoelectric ...
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