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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Identifying Categorical Land Use Transition and Land Degradation in Northwestern Drylands of Ethiopia

Zewdie, Worku, Csaplovics, Elmar 08 June 2016 (has links)
Land use transition in dryland ecosystems is one of the major driving forces to landscape change that directly impacts the welfare of humans. In this study, the support vector machine (SVM) classification algorithm and cross tabulation matrix analysis are used to identify systematic and random processes of change. The magnitude and prevailing signals of land use transitions are assessed taking into account net change and swap change. Moreover, spatiotemporal patterns and the relationship of precipitation and the Normalized Difference Vegetation Index (NDVI) are explored to evaluate landscape degradation. The assessment showed that 44% of net change and about 54% of total change occurred during the study period, with the latter being due to swap change. The conversion of over 39% of woodland to cropland accounts for the existence of the highest loss of valuable ecosystem of the region. The spatial relationship of NDVI and precipitation also showed R2 of below 0.5 over 55% of the landscape with no significant changes in the precipitation trend, thus representing an indicative symptom of land degradation. This in-depth analysis of random and systematic landscape change is crucial for designing policy intervention to halt woodland degradation in this fragile environment.
142

Zpracování uživatelských recenzí / Processing of User Reviews

Cihlářová, Dita January 2019 (has links)
Very often, people buy goods on the Internet that they can not see and try. They therefore rely on reviews of other customers. However, there may be too many reviews for a human to handle them quickly and comfortably. The aim of this work is to offer an application that can recognize in Czech reviews what features of a product are most commented and whether the commentary is positive or negative. The results can save a lot of time for e-shop customers and provide interesting feedback to the manufacturers of the products.
143

Porovnání možností komprese multimediálních signálů / Comparison of Multimedia Signal Compression Possibilities

Špaček, Milan January 2013 (has links)
Thesis deals with multimedia signal comparison of compression options focused on video and advanced codecs. Specifically it describes the encoding and decoding of video recordings according to the MPEG standard. The theoretical part of the thesis describes characteristic properties of the video signal and justification for the need to use recording and transmission compression. There are also described methods for elimination of encoded video signal redundancy and irrelevance. Further on are discussed ways of measuring the video signal quality. A separate chapter is focused on the characteristics of currently used and promising codecs. In the practical part of the thesis were created functions in Matlab environment. These functions were implemented into graphic user interface that simulates the activity of functional blocks of the encoder and decoder. Based on user-specified input parameters it performs encoding and decoding of any given picture, composed of images in RGB format, and displays the outputs of individual functional blocks. There are implemented algorithms for the initial processing of the input sequence including sub-sampling, as well as DCT, quantization, motion compensation and their inverse operations. Separate chapters are dedicated to the realisation of codec description in the Matlab environment and to the individual processing steps output. Further on are mentioned compress algorithm comparisons and the impact of parameter change onto the final signal. The findings are summarized in conclusion.
144

Vyhledávání obrazu na základě podobnosti / Image search using similarity measures

Harvánek, Martin January 2014 (has links)
There are these methods implemented: circular sectors, color moments, color coherence vector and Gabor filters, they are based on low-level image features. These methods were evaluated after their optimal parameters were found. The finding of optimal parameters of methods is done by measuring of classification accuracy of learning operators and usage of operator cross validation on images in program RapidMiner. Implemented methods are evaluated on these image categories - ancient, beach, bus, dinousaur, elephant, flower, food, horse, mountain and natives, based on total average precision. The classification accuracy result is increased by 8 % by implemented modification (HSB color space + statistical function median) of original method circular sectors. The combination of methods color moments, circular sectors and Gabor filters with weighted ratio gives the best total average precision at 70,48 % and is the best method among all implemented methods.
145

Sada JavaAppletů pro demonstraci zpracování řeči / Set of JavaApplets Demonstrations for Speech Processing

Kudr, Michal January 2010 (has links)
The goal of the thesis is being familiar with methods a techniques used in speech processing. Using the obtained knowledge I propose three JavaApplets demonstrating selected methods. In this thesis we can find the theoretical analysis of selected problems.
146

Návrh a realizace aktivního trojfázového usměrňovače / Concept of three-phase active rectifier

Bareš, Jiří January 2016 (has links)
This work deals with three-phase active rectifier control. In first, theoretical part it describes several control strategies with focus on voltage oriented control. For this type of control a design is worked out, and created model and its simulation is described. Second, practical part deals with realisation on microcontroller TMS320F28335, which is main processing unit of device lent by company Elcom. Therefore in this part abilities and settings of the controller along with developped control algorithm are described. Reached results of measurement are then presented and in the conclusion they are evaluated.
147

Rozšíření pro pravděpodobnostní lineární diskriminační analýzu v rozpoznávání mluvčího / Extensions to Probabilistic Linear Discriminant Analysis for Speaker Recognition

Plchot, Oldřich Unknown Date (has links)
Tato práce se zabývá pravděpodobnostními modely pro automatické rozpoznávání řečníka. Podrobně analyzuje zejména pravděpodobnostní lineární diskriminační analýzu (PLDA), která modeluje nízkodimenzionální reprezentace promluv ve formě \acronym{i--vektorů}.  Práce navrhuje dvě rozšíření v současnosti požívaného PLDA modelu. Nově navržený PLDA model s plným posteriorním rozložením  modeluje neurčitost při generování i--vektorů. Práce také navrhuje nový diskriminativní přístup k trénování systému pro verifikaci řečníka, který je založený na PLDA. Pokud srovnáváme původní PLDA s modelem rozšířeným o modelování  neurčitosti i--vektorů, výsledky dosažené s rozšířeným modelem dosahují až 20% relativního zlepšení při testech s krátkými nahrávkami. Pro delší  testovací segmenty  (více než jedna minuta) je zisk v přesnosti  menší, nicméně přesnost nového modelu není nikdy menší než přesnost výchozího systému.  Trénovací data jsou ale obvykle dostupná ve formě dostatečně dlouhých segmentů, proto v těchto případech použití nového modelu neposkytuje žádné výhody při trénování. Při trénování může být použit původní PLDA model a jeho rozšířená verze může být využita pro získání skóre v  případě, kdy se bude provádět testování na krátkých segmentech řeči. Diskriminativní model je založen na klasifikaci dvojic i--vektorů do dvou tříd představujících oprávněný a neoprávněný soud (target a non-target trial). Funkcionální forma pro získání skóre pro každý pár je odvozena z PLDA a trénování je založeno na logistické regresi, která minimalizuje vzájemnou entropii mezi správným označením všech soudů a pravděpodobnostním označením soudů, které navrhuje systém. Výsledky dosažené s diskriminativně trénovaným klasifikátorem jsou podobné výsledkům generativního PLDA, ale diskriminativní systém prokazuje schopnost produkovat lépe kalibrované skóre. Tato schopnost vede k lepší skutečné přesnosti na neviděné evaluační sadě, což je důležitá vlastnost pro reálné použití.
148

On Modeling Elastic and Inelastic Polarized Radiation Transport in the Earth Atmosphere with Monte Carlo Methods: On Modeling Elastic and Inelastic PolarizedRadiation Transport in the Earth Atmosphere withMonte Carlo Methods

Deutschmann, Tim 08 January 2015 (has links)
The three dimensional Monte Carlo radiation transport model McArtim is extended to account for the simulation of the propagation of polarized radiation and the inelastic rotational Raman scattering which is the cause of the so called Ring effect. From the achieved and now sufficient precision of the calculated Ring effect new opportunities in optical absorption spectroscopy arise. In the calculation the method of importance sampling (IS) is applied. Thereby one obtains from an ensemble of Monte Carlo photon trajectories an intensity accounting for the elastic aerosol particle-, Cabannes- and the inelastic rotational Raman scattering (RRS) and simultaneously an intensity, for which Rayleigh scattering is treated as an elastic scattering process. By combining both intensities one obtains the so called filling-in (FI, which quantifies the filling-in of Fraunhofer lines) as a measure for the strength of the Ring effect with the same relative precision as the intensities. The validation of the polarized radiometric quantities and the Ring effect is made by comparison with partially published results of other radiation transport models. Furthermore the concept of discretisation of the optical domain into grid cells is extended by making grid cells arbitrarily joining into so called clusters, i.e. grid cell aggregates. Therewith the program is able to calculate derivatives of radiometrically or spectroscopically accessible quantities, namely the intensities at certain locations in the atmospheric radiation field and the light path integrals of trace gas concentrations associated thereto, i.e. the product of the DOAS (differential optical absorption spectroscopy) method, with respect to optical properties of aerosols and gases in connected spatial regions. The first and second order derivatives are validated through so called self-consistency tests. These derivatives allow the inversion of three dimensional tracegas and aerosol concentration profiles and pave the way down to 3D optical scattered light tomography. If such tomographic inversion scheme is based solely on spectral intensitites the available second order derivatives allows the consideration of the curvature in the cost function and therefore allows implementation of efficient optimisation algorithms. The influence of the instrument function on the spectra is analysed in order to mathematically assess the potential of DOAS to a sufficient degree. It turns out that the detailed knowledge of the instrument function is required for an advanced spectral analysis. Concludingly the mathematical separability of narrow band signatures of absorption and the Ring effect from the relatively broad band influence of the elastic scattering processes on the spectra is demonstrated which corresponds exactly to the DOAS principle. In that procedure the differential signal is obtained by approximately 4 orders of magnitude faster then by the separate modelling with and without narrow band structures. Thereby the fusion of the separated steps DOAS spectral analysis and subsequent radiation transport modeling becomes computationally feasible.:1.1. Radiation Transport Modeling and Atmospheric State Inversion 1.2. Vector RTE Solution Methods 1.3. Scope of the Thesis 1.4. Outline of the Thesis 2.1. General Structure 2.1.1. Chemical Composition of the Gas Phase 2.1.2. The Troposphere, Temperature and Pressure Vertical Structure 2.1.3. The Stratosphere 2.2. Aerosols and Clouds 2.2.1. Classification and Morphology 2.2.2. Water Related Particle Growth and Shrinking Processes 2.2.3. Size Spectra and Modes 3.1. Electromagnetic Waves 3.1.1. Maxwell\''s Equations 3.1.2. Measurement of Electromagnetic Waves 3.1.3. Polarization State of EM Waves 3.1.4. Stokes Vectors 3.2. Scattering and Absorption of EM Waves by Molecules and Particles 3.2.1. General Description of Scattering and Coordinate Systems 3.2.2. Molecular Scattering 3.2.3. Molecular Absorption Processes and Electronic Molecular States 3.2.4. Scattering On Spherical Particles - Mie Theory 3.3. Mathematical Description of Radiation Transport 3.3.1. Radiance and Irradiance 3.3.2. Absorption, Scattering and Extinction Coefficients 3.3.3. Optical Thickness and Transmission 3.3.4. Scattering 3.3.5. Incident (Ir)Radiance 3.3.6. The Black Surface Single Scattering Approximation 3.3.7. Radiative Transfer Equations 4.1. General Monte Carlo Methods 4.1.1. Numerical Integration 4.1.2. Importance Sampling and Zero Variance Estimates 4.1.3. Optimal Sampling 4.1.4. Sampling from Arbitrary Distributions 4.2. Path Generation or Collision Density Estimation 4.2.1. Discretization of the Optical Domain into Cells and Clusters 4.2.2. RTE Integral Form 4.2.3. Formal Solution of the IRTE 4.2.4. Overview on Monte Carlo RTE Solution Algorithms 4.2.5. Crude Monte Carlo 4.2.6. Sequential Importance Sampling (SIS) or Path Generation 4.3. Importance Sampling in Monte Carlo SIS Radiative Transfer 4.3.1. Weights for Alternate Kernels 4.3.2. Weights in the Calculation of RTE Functional Estimates 4.3.3. Application of IS to Mie Phase Functions Scatter Angle Sampling 5.1. Radiances, Intensities and the Reciprocity Theorem 5.1.1. Scalar Radiance Estimates 5.1.2. Backward Monte Carlo Scalar Radiance 5.1.3. Vector Radiances 5.2. Radiance Derivatives 5.2.1. Variables for Radiance Derivatives 5.3. Validation of Functionals 5.3.1. Validation of Vector Radiances 5.3.2. Validation of Radiance Derivatives 6.1. A Simply Structured Instrument Forward Model 6.2. Pure Atmospheric Spectra and Absorption 6.2.1. Direct Light Spectra 6.2.2. Scattered Sun Light Spectra 6.3. (D)OAS from the Perspective of Radiative Transfer Modeling 6.3.1. (Rest) Signatures of Weakly Absorbing Gases 6.3.2. Spectroscopic Measurements and Standard DOAS 6.4. DOAS Analysis Summary 6.4.1. DSCD Retrieval 6.4.2. Inversion 7.1. RRS-Modified RTE 7.1.1. RRS Cross Sections for Scattering out and into a Wavelength 7.1.2. Modification of the RTE Loss and Source Terms 7.2. Intensity Estimates Considering Rotational Raman Scattering 7.2.1. RRS in the Path Sampling Procedure 7.2.2. Adjoint RRS Correction Weights 7.2.3. Local Estimates of Intensities with RRS 7.2.4. Intensity Estimates 7.3. Ring Spectra 7.3.1. Elastic Biasing of the Local Estimates 7.3.2. Cumulative Weights and Local Estimates 7.3.3. Test of the Elastic Biasing 7.4. Validation 7.4.1. Comparison to an Analytic Single Scattering Code 7.4.2. Single Scattering Model Including Rotational Raman Scattering 7.4.3. Multiple Scattering Model Comparison 7.4.4. Comparison with A Measurement 7.4.5. Validation of Approximate Methods For Ring Effect Modeling 7.5. Summary and Discussion 8.1. Status and Summary 8.1.1. Ring-Effect and Absorption Corrected Radiances 8.1.2. Derivatives of Radiometric Quantities Accessible Through Spectroscopy 8.1.3. Polarization 8.1.4. Time Integrated Sensitivities for 3D UV/vis/NIR Remote Sensing 8.2. Outlook A.1. Zero Variance Estimates A.2. Free Path Length Sampling in a Homogeneous Medium A.3. Cumulative Differential Scatter Cross Sections A.3.1. Cardanic formulas A.3.2. Rayleigh and Raman Phase Functions A.3.3. Henyey-Greenstein Model A.3.4. Legendre Polynomial Phase Function Model A.3.5. Table Methods A.4. Greens Function in the Derivation of the IRTE A.5. Source Code For Stokes Vector Transformation Plot B.1. 1st Order Derivatives B.2. 2nd Order Derivatives B.3. Hessian of Integrals Depending on Many Variables C.1. Slit Function f Derivatives C.2. Signal Sn Derivatives C.3. Chi Square Spline Fitting C.3.1. Constrained Non-Linear Least Square Problem C.3.2. Spline Fitting C.3.3. Jacobians and Hessian
149

Рачунар у настави аналитичке геометрије у гимназији / Računar u nastavi analitičke geometrije u gimnaziji / The computer in teaching analytic geometry in the gymnasium

Prentović Branko 27 April 2015 (has links)
<p>У Докторској дисертацији је извршена методичкa трансформација садржа-<br />ја&nbsp; аналитичке&nbsp; геометрије,&nbsp; у&nbsp; наставном&nbsp; систему&ndash; настава&nbsp; уз&nbsp; помоћ<br />рачунара,&nbsp; адекватним&nbsp; избором&nbsp; садржаја,&nbsp; израдом&nbsp; одговарајућих<br />генеричких органи-затора уз коришћење образовног софтвераGeoGebra и<br />Mathematica. Обрађен је дидактички систем настава уз помоћ рачунара,<br />анализом међусобне зависности фактора наставе, анализом дидактичких<br />принципа,&nbsp; класификацијом&nbsp; и&nbsp; приказом&nbsp; наставних&nbsp; метода,&nbsp; уз&nbsp; подесно<br />формиране&nbsp; генеричке&nbsp; организаторе.&nbsp; Експериментално&nbsp; истраживање&nbsp; је<br />потврдило могућност примене наставе уз помоћ рачунара, као и позитиван<br />утицај на реализацију циљева и задатака, на укупан образовни учинак и<br />подизање нивоа ефикасности савремене наставе.</p> / <p>U Doktorskoj disertaciji je izvršena metodička transformacija sadrža-<br />ja&nbsp; analitičke&nbsp; geometrije,&nbsp; u&nbsp; nastavnom&nbsp; sistemu&ndash; nastava&nbsp; uz&nbsp; pomoć<br />računara,&nbsp; adekvatnim&nbsp; izborom&nbsp; sadržaja,&nbsp; izradom&nbsp; odgovarajućih<br />generičkih organi-zatora uz korišćenje obrazovnog softveraGeoGebra i<br />Mathematica. Obrađen je didaktički sistem nastava uz pomoć računara,<br />analizom međusobne zavisnosti faktora nastave, analizom didaktičkih<br />principa,&nbsp; klasifikacijom&nbsp; i&nbsp; prikazom&nbsp; nastavnih&nbsp; metoda,&nbsp; uz&nbsp; podesno<br />formirane&nbsp; generičke&nbsp; organizatore.&nbsp; Eksperimentalno&nbsp; istraživanje&nbsp; je<br />potvrdilo mogućnost primene nastave uz pomoć računara, kao i pozitivan<br />uticaj na realizaciju ciljeva i zadataka, na ukupan obrazovni učinak i<br />podizanje nivoa efikasnosti savremene nastave.</p> / <p>In this doctoral dissertation, methodical transformation of content analytic<br />geometry, is carried out, in the educational system - a computer-assisted<br />teaching, by appropriate selection of content, making appropriate generic<br />organizers using educational software GeoGebra and Mathematica.<br />Didactic teaching system, computer-assisted teaching, was processed, by<br />analyzing the factors of teaching and didactic principles, classification and<br />presentation of teaching methods, with the adequately created generic<br />organizers. Experimental research has confirmed the apossibility of<br />computer-assisted teaching, as well as a positive impact on the realization<br />of goals and tasks, on the overall educational impact and raising the<br />efficiency of modern teaching.</p>
150

Biokompatibilita a imunokompatibilita polymerů určených pro genovou terapii / Biocompatibility and immunocompatibility of polymers for gene therapy

Matyášová, Veronika January 2010 (has links)
Gene therapy is a potential strategy for treatment of diseases caused by a gene defect. Recent studies are involved particulary in the cure of diseases caused by single gene defect (cystic fibrosis, haemophilia, muscular dystrophy etc.). Our work is part of a project aiming at developing ex vivo non-viral gene delivery systems that could be used for the treatment of ocular and cardiovascular diseases. The gene vectors are biodegradable polymeric carriers based on poly-α-amino acids. These polyplexes should transfect target cells which are supposed to be seeded on polyimide membranes. The biodegradable polymer membrane will be implanted into the retina or used as a coating for cardiovascular prosthesis. As a cover of the implantable membranes we used polymerized methacrylamide-modified gelatin forming hydrogels and mediating a growth support for transfected cells. We focus on material bio- and immunocompatibility/immunoacceptability. The results indicated a very good bio- and immunocompatibility of the gelatin B hydrogel both in vitro and in vivo. The gelatin B hydrogel did not cause erythrocytes lysis, stimulation of proliferation (spontaneous or mitogen-induced) of mouse or human lymphoid cells, neither production of cytokines or NO in vitro. Histological examination following subcutaneous...

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