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Detection of the forest disturbance using UAV multispectral photogrammetry
Minařík, Robert ; Langhammer, Jakub (advisor) ; Hofierka, Jaroslav (referee) ; Miřijovský, Jakub (referee)
Epidemic (calamitous) overpopulations of bark beetles (Scolytinae Latreille, 1804) caused by climate change and inappropriate tree species composition currently have the most negative impacts on the development of Europe's mixed and boreal forests. Epidemic overpopulations can significantly undermine forest health and cause economic losses. It is therefore essential to use appropriate methods for early detection of bark beetle disturbance. Multispectral remote sensing (RS) methods using unmanned aerial systems (UAS) represent a new option for contactless landscape monitoring providing quantitative information on vegetation health with high spatiotemporal resolution and therefore appear to be suitable for early detection of disturbance. The thesis focused on the validation of the use of UAS multispectral photogrammetry and image classification methods for the detection of individual forest disturbance stages caused by the spruce bark beetle (Ips typographus Linnaeus, 1758) at the level of individual trees for the study of disturbance dynamics. In this dissertation, all important aspects of detection were elaborated: analysis of the suitability of spectral bands for disturbance detection, radiometric calibration of multispectral cameras, automated segmentation of individual canopies from...
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Convergence of the embedding scheme
Hofierka, Jaroslav ; Klimeš, Jiří (advisor) ; Čížek, Martin (referee)
To obtain accurate adsorption energies of molecules on surfaces is a challenging task as the methods with sufficient accuracy are too computationally demanding to be applied to the systems of interest. Embedding theories provide a natural remedy: focus the computation on a small region and incorporate the effects of the environment. In this thesis, embedding schemes and the response of many-electron systems to an adsorbed impurity are investigated. To this end, two approaches are used: tight-binding and ab initio. In the tight-binding method, the Green's function formalism is studied and explicit expressions for Green's functions of various one- and two-dimensional models are obtained. Using this formalism, we study qualitatively the local density of states and adsorption energies. In the second part of this thesis, state-of-the-art ab initio methods are employed to study convergence of the subtractive embedding scheme for adsorption energies of small closed-shell systems on two-dimensional graphene and hexagonal boron nitride. The efficiency and applicability of the scheme are assessed for neon and hydrogen fluoride as adsorbates. We found that the studied embedding method works better for neon compared to hydrogen fluoride, which may be explained by the use of a two-body dispersion correction.
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Lattice energies of molecular solids
Hofierka, Jaroslav ; Klimeš, Jiří (advisor) ; Bludský, Ota (referee)
Molecular solids are important materials with many applications in various fields of science and industry. They are often characterized by a rich phase diagram and the ability to adopt multiple crystal structures (polymorphism). To describe small energy differences between various phases or polymorphs, accurate quantum mechanical methods are needed. In this thesis, lattice energies of methane, methanol, ammonia, and carbon dioxide are calculated using two different approaches, namely, the fragment approach and the periodic boundary conditions (PBC) approach. These two schemes have different requirements in terms of compute cost and human time needed to obtain precise results. In the fragment scheme, the Hartree-Fock, MP2, and CCSD(T) quantum mechanical methods are employed. In the PBC scheme, the Hartree- Fock and MP2 lattice energies are calculated. For all four systems, which differ in the nature of prevalent intermolecular interactions, a very good agreement in the range of 0.1 - 0.6 kJ/mol was found between both approaches at the MP2 level.
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