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Stanovení charakteristik cyklostacionárního detektoru signálu OFDM. / Assignment of the OFDM signal cyclostationary detector behaviour.Lehocký, Jiří January 2012 (has links)
Master’s thesis belongs to the Cognitive radio network sphere. These networks utilize frequency spectrum more effectively than networks used in present radio communications. The Cognitive radio concept makes coexistence of classic and cognitive radio networks possible. Attention is aimed at spectrum sensing as the key task of the Cognitive radio. Main properties of the cyclostationary detector, as the detector, that reaches high probability of the detection at a very low signal to noise ratio with apriori knowledge of the transmitted signal's cyclic frequency, are examined in this paper. The OFDM signals, that inherit cyclostationarity from cyclic prefix, used in the real systems have been chosen for testing the properties of the detector. The influences of decimation and multipath propagation on the probability of detection are quantitatively expressed. The optimal values for the weights of the multicycle detector are determined.
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Stabilita krystalů pevných látek z prvních principů / Stability of crystalline solids from first principlesŘehák, Petr January 2009 (has links)
This work deals with study of stability of solid crystals under isotropic loading. Ab initio methods were used for this purpose. Crystals of four fcc metals (Al, Cu, Ir, Au) and diamond were subjected to simulated isotropic tensile deformation and maximum value of isotropic stress was evaluated for them. Consequently, phonon spectra were calculated for several strain values in order to assess crystal stability. Phonon instabilities in dispersion curves of diamond, Al, Ir and Au appeared at strains lower than those corresponding to their decohesion. This appearance of instability determinates the value of ideal strength. However, significant reduction (by about 20%) was found only in the cases of Au and Ir.
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Dielektrické vlastnosti tenkých vrstev oxidů niobu a tantalu / Dielectric Properties of Thin Tantalum and Niobium Oxide LayersAbuetwirat, Inas Faisel January 2014 (has links)
Dielektrická relaxační spektroskopie je jednou z užitečných metod pro studium molekulární dynamiky materiálů. Díky nedávnému pokroku v přístrojové a měřicí technice je dnes možné získat dielektrické spektrum v širokém frekvenčním intervalu a pro velice rozdílné materiály. Cílem mé práce bylo studium dielektrických relaxačních spekter a vodivosti oxidů titanu, niobu, tantalu, lanthanu a hafnia pro katody pracující na principu studené emise. Cílem výzkumu bylo analyzovat frekvenční a teplotní chování těchto oxidů, včetně jejich vodivosti, v širokém frekvenčním a teplotním rozsahu, a pokusit se stanovit původ relaxačního mechanismu. Vzhledem k tomu, že původně zadaný rozsah oxidů byl dosti široký, soustředila se pozornost pouze na oxidy tantalu a niobu, rovněž s ohledem na jejich aplikace v elektrolytických kondenzátorech. Elektrické, tepelné a mechanické (při zpracování) vlastnosti oxidů tantalu a niobu jsou dnes již dobře prozkoumány. K dispozici je však jen málo poznatků o jejich dielektrických relaxačních mechanismech. Výsledky získané pro Ta2O5 ukazují existence relaxačního maxima, nacházejícího se v experimentálně dostupném teplotním a frekvenčním intervalu 187 K – 385 K a 1 Hz – 10 MHz. Frekvence ztrátového maxima se řídí Arrheniovým zákonem s aktivační energií 0.048 eV. Ve vodivostních spektrech vykazují tenké vrstvy Ta2O5 na nízkých frekvencích ustálenou hodnotu a při vysokých frekvencích monotónní nárůst, který závisí na teplotě. Pozorovanou vodivost lze popsat mocninnou funkcí s exponentem nepatrně větším než jedna (tzv. superlineární závislost). Výsledky získané pro Nb2O5 v podobné teplotní a frekvenční oblasti, 218 K – 373 K, 1 Hz – 1 MHz rovněž ukazují jedno relaxační maximum. Frekvence ztrátového maxima se opět řídí Arrheniovým zákonem s poněkud vyšší aktivační energií 0.055 eV. Niobové kondenzátory vykazují vodivostní mechanismus shodný s kondenzátory tantalovými.
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Studium srážek protonů a těžkých iontů v experimentu ATLAS na LHC / Study of proton-proton and heavy-ion collisions with the ATLAS experiment at the LHCBalek, Petr January 2016 (has links)
Title: Study of proton-proton and heavy-ion collisions with the ATLAS experi- ment at the LHC Author: Mgr. Petr Balek Department: Institute of Particle and Nuclear Physics Supervisor: Doc. RNDr. Jiří Dolejší, CSc. Abstract: The presented results show a suppression in a production of charged hadrons in heavy-ion collisions with respect to the production measured in proton- proton collisions. Lead-lead data at √ sNN = 2.76 TeV were recorded by the AT- LAS experiment at the LHC in 2010 and 2011 and they have a total integrated luminosity of 0.15 nb−1 , and proton-proton data at √ s = 2.76 TeV were recorded in 2011 and 2013 having an integrated luminosity of 4.2 nb−1 . The results are presented in wide transverse momentum (0.5 < pT < 150 GeV) and pseudorapid- ity (|η| < 2) ranges, and also in different centrality intervals of Pb+Pb collisions. Nuclear modification factor RAA shows a clear pT-dependence with a minimum at around 7 GeV, however above 60 GeV, it reaches a plateau with no significant pT-dependence. As a function of |η|, the RAA is flat over whole pT region. Keywords: ATLAS detector, heavy-ion collisions, charged-hadron spectra, nuclear modification factor RAA
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Studium elektronových přeskoků v systému konjugovaných molekul metodami kvantové mechaniky. / Quantum mechanical study of the electron hoping processes of conjugated systems.Fatková, Kateřina January 2020 (has links)
This thesis uses previously proposed methodology for simulations of all-trans- polyenes with conjugated systems. Dynamic properties, especially the mean lifeti- mes of the excited states, of these molecules were systematically simulated. Obta- ined data shows that the method is still too time-consuming for polyene molecules with more than 20 carbon atoms, including most carotenoids. Thus, a study of active space reduction was performed with the model tetradecaheptaene molecule with regards to excited state mean lifetimes. A new, less time-consuming method would need further simulation studies. Moreover, static spectra of the these mo- lecules were studied as well, yielding a comparison of different DFT and ab-initio approaches. 1
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Stará a nová levice na politické scéně České republiky / Old and new left in Czech RepublicBlažeková, Radka January 2017 (has links)
The topic of the diploma thesis is a comparison of the old and new left in the Czech Republic. The diploma thesis focuses on a comparison of the selected relevant left-wing political groups operating in the Czech Republic. The thesis examines differences and similarities between the KSČM, the socialist wing of ČSSD on one side and the Green Party and the left-liberal tendencies and offshoots of the ČSSD (such Idealists) on the other hand. The work is divided into three main parts. The first part of the thesis is theoretical. The theoretical part defines main terms such as a political party, political movement, left-right axis of the political spectrum, the old left, the new left etc. The explanation of the terms is very important for understanding the thesis. In the second part of this thesis, I analyze single significant and relevant political parties. I focus on the origin and development of political parties and their electoral program, their attitude to selected issues, electorate, potential cooperation between themselves and so on. The third part is comparative. The goal of this thesis is to find out whether the analyzed political parties fulfill leftist characteristic. Next goal of this thesis is to find out whether the classification on left-right axis of the political spectrum is still...
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Mladí lidé s poruchou autistického spektra na online sociálních sítích / Young people with autistic spectrum disorder on online social networksTrojanová, Lucie January 2019 (has links)
Online social networking along with computer mediated communication (CMC) has become a crucial part of teenagers' everyday life. Today it is vital to be a member of online peer community in order to stay in touch and maintain friendships. For teenagers with autism spectrum disorder (ASD) social networks are undoubtedly a way to create and maintain friendships without the difficulties that come along with the diagnosis. Autism spectrum disorders affect mainly social competencies, communication skills and imagination. The thesis is focusing on how social networking could help to improve social competencies of teenagers with ASD. In order to examine this topic it is important to focus on the connection between offline and online relationships that teenagers with ASD maintain in their peer group. Therefore a quantitative measurement of loneliness and social dissatisfaction was used in combination with semi-structured interviews covering the topics of relationship with peers, using social networks and internet in general. Results of an ASD group were then compared with a group of a neurotypical control group. The comparison between the groups showed that ASD group does not have a great interest in participating in social networking sites, except for online messengers. That could be due to a smaller...
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Teorie metafor v rámci výzkumů poruch autistického spektra / The Theory of Metaphor within Ressearches in Autism Spectrum DisordersProcházková, Theresa January 2019 (has links)
The thesis deals with the theory of metaphor in selected pieces of research that focus on autism spectrum disorders. Patients with autism spectrum disorders show weakened ability to communicate and they have trouble understanding everyday social interactions as they are not able to identify with thoughts and feelings of others. They also have trouble understanding metaphors, irony, hyperbolical speech, etc. In their book Metaphors we live by Lakoff and Johnson claim that our language and our thinking are based on metaphors, i.e. on abstraction. The hypothesis is that various pieces of research focusing on how people on the autism spectrum understand metaphors draw on different definitions of metaphor and different approaches to it. The theory of metaphor that is presented in Lakoff's and Johnson's work should be able to provide theoretical framework for coherent understanding of a metaphor. It should also have the potential to point out the differences between particular pieces of research and possible shortages within them.
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Poruchy autistického spektra ve výuce na středních zdravotnických školách / Autism spectrum disorderčs in the education system of the secondary nursing schoolsNiederlová, Veronika January 2020 (has links)
Autism spectrum disorders (ASD) are characterized by deficits in the areas of communication and social interaction, stereotypic behaviour and changes in the sensory processing. These symptoms pose challenges to everyday situations such as visits to the doctor's office, which are more stressful for children with ASD and their parents than for the general population. Furthermore, more than one-third of parents have encountered refusal to provide medical care for their child because of ASD. In our diploma project, we combined the parent's reports with an analysis of international sources to create a project called AutFriendly which aims to increase the knowledge of the Czech healthcare practitioners about ASD. In the presented thesis, we summarize the theoretical background in the field of healthcare provision for people with ASD and we review current Czech and international literature to show how the topic of ASD is addressed in the education of healthcare practitioners. In the practical part of the thesis, we summarize our two-year experience with the AutFriendly project. First, we created a two- hour AutFriendly workshop for the students of secondary schools of nursing and we put it into practice with more than 250 participating students of the Czech secondary schools of nursing. Second, we...
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Specifika vybraných přístupů v předškolním vzdělávání dětí s poruchami autistického spektra / Specific of selected approaches in pre-shcool education of children with autism spectrumStrýčková, Karolína January 2020 (has links)
The presented masters thesis deals with selected educational approaches that are used in preschool children with autism spectrum disorder. The theoretical part defines the broad concept of autism, the role of preschool education, and describes methods of work with autistic children of the given age. It also explains the basic characteristics of the Son-Rise program, Applied Behavioral Analysis and TEACCH. In the empiric part within the qualitative research survey, the thesis aims to obtain an overview of the views of teachers focused on the advantages and disadvantages of selected methods. KEYWORDS autism spectrum disorders, TEACCH, Son-Rise program, applied behavior analysis, educational approaches, autism, preschool education
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