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National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Short-term cyclic paleoenvironmental variations in Middle Turonian hemipelagic deposits, Bohemian Cretaceous Basin
 Voženílková, Kristýna ; Uličný, David (advisor) ; Chadimová, Leona (referee)
The sedimentary record of the Turonian substage (Upper Cretaceous) offers an opportunity to examine climatic variations in a time of peak greenhouse climate. In the Bohemian Cretaceous Basin, recent cyclostratigraphic studies examined the cyclic variations of sedimentary environments of the Lower and Upper Turonian, while the cyclostratigraphy of the Middle Turonian substage has remained less understood. This thesis applied methods of spectral analysis to well logs and elemental composition data from several boreholes located in the central part of the Bohemian Cretaceous Basin, in order to better understand the environmental variations of the Middle Turonian substage and their possible astronomical forcing. A short eccentricity (~100 kyr) signature has been found in well log data, as well as the carbonate content of the Bch-1 borehole section and correlated over more than 20 km within the study area. Biogenic carbonate production is considered to be the cause of astronomically controlled cyclicity in content of Ca (proxy for CaCO3). For most of the substage, the carbonate cyclicity was shown to be decoupled from clastic sediment input variations, except the basal part of the Middle Turonian succession where clastic proxies are in phase with carbonate variations. It is proposed that the...
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Artificial inteligence and its application in the coccolith determination
 Voženílková, Kristýna ; Holcová, Katarína (advisor) ; Svobodová, Andrea (referee)
Automatic determination of objects using neural networks has been applied in many fields of study, however, this approach has only rarely been used in paleontology. The goal of this bachelor thesis is to evaluate a method of automatic determination of coccoliths using neural networks. This method has been proposed by the Cogniware company. Cyclicargolithus floridanus and Cyclicargolithus abisectus have been chosen for the testing of the neural network. So far, the network has been trained to determine only C. floridanus, and managed to recognize the typical speciman of this species with 99% accuracy. This thesis provides a basic overview of the coccolith group and neural networks. It also describes the method used to prepare data for the neural network. Key words: calcareous nannoplankton, Reticulofenestra, morfology, artificial intelligence, neural network
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See also: similar author names
3 Voženílková, Kateřina
2 Voženílková, Klára
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