Národní úložiště šedé literatury Nalezeno 7 záznamů.  Hledání trvalo 0.00 vteřin. 
Breaking of Rod-shaped Model Material during Compression.
Kulaviak, Lukáš ; Pěnkavová, Věra ; Růžička, Marek ; Punčochář, Miroslav ; Zámostný, P. ; Grof, Z. ; Štěpánek, F. ; Schöngut, M. ; Havlica, Jaromír
The breakage of a model anisometric dry granular material caused by uniaxial compression was studied. The bed of uniform rod-like pasta particles (8 mm long, aspect ratio 1:8) was compressed (Gamlen Tablet Press) and their size distribution was measured after each run (Dynamic Image Analysing). The compression dynamics was recorded and the effect of several parameters was tested (rate of compression, volume of granular bed, pressure magnitude and mode of application). Besides the experiments, numerical modelling of the compressed breakable material was performed as well, employing the DEM approach (Discrete Element Method). The comparison between the data and the model looks promising.
Plný tet: SKMBT_C22018011012170 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
Powder Rheology of Nanocrystalic Particles.
Kulaviak, Lukáš ; Pěnkavová, Věra ; Růžička, Marek ; Punčochář, Miroslav ; Zámostný, P. ; Grof, Z. ; Štěpánek, F. ; Schöngut, M. ; Havlica, Jaromír
Pigments are mostly nanometric powder of anisometric particles providing complex rheological behaviour. The interparticle forces of grains (> 100 μm) are based on direct contact, which is mainly influenced by the particle size and shape. On the other hand powder (< 4 μm) and especialy nanometric powder (< 100 nm) is influenced mainly by electrostatic charges and by moisture (respectively by the liquid and solid bridges forming). However the morphology affects the surface area and thus the distribution of surface charge and\nthe moisture content on/in single particle. Last but not least, it is also good to know the history of the powder, i.e. the effect of aging and the memory of the powder on the strength of the material. The nanometric powder TiO2 was chosen as a demonstration material and measuring device was FT4 powder rheometer.
Plný tet: SKMBT_C22018011012520 - Stáhnout plný textPDF
Plný text: content.csg - Stáhnout plný textPDF
Image processing with neural networks
Gróf, Zoltán ; Pohl, Jan (oponent) ; Jirsík, Václav (vedoucí práce)
This bachelor’s thesis centralizes on the possible uses of neural networks in the field of computer vision. This work contains basic theoretic knowledge of the field of neural networks and image processing. It discusses how successfully can neural networks be applied through the separate steps of image processing, what kind of neural networks are suitable for these steps, and what are the problems that might appear with their use. The work discusses the fields of classification and image understanding in a more detailed level. It’s shown how the use of neural networks can be appropriate in these applications. An own program was created as part of this work to demonstrate the classification capabilities of neural networks. It’s shown a neural network is created and trained for the recognition of handwritten numbers. The trained neural network was subject to different tests, through which the conclusion was reached, that it works with a high success rate, but is sensitive to changes in the input objects: change of size and location. A number of possible solutions were designed for this problem.
The decision boundary
Gróf, Zoltán ; Hynčica, Tomáš (oponent) ; Jirsík, Václav (vedoucí práce)
The main aim of this master's thesis is to describe the subject of the implementation of decision boundaries with the help of artificial neural networks. The objective is to present theoretical knowledge concerning this field and on practical examples prove these statements. The work contains basic theoretical description of the field of pattern recognition and the field of feature based representation of objects. A classificator working on the basis of Bayes decision is presented in this part, and other types of classificators are named as well. The work then deals with artificial neural networks in more detail; it contains a theoretical description of their function and their abilities in the creation of decision boundaries in the feature plane. Examples are shown from literature for the use of neural networks in corresponding problems. As part of this work, the program ANN-DeBC was created using Matlab, for the generation of practical results about the usage of feed-forward neural networks for the implementation of decision boundaries. The work contains a detailed description of this program, and the achieved results are presented and analyzed. It is shown as well, how artificial neural networks are creating decision boundaries in the form of geometrical shapes. The effects of the chosen topology of the neural network and the number of training samples on the success of the classification are observed, and the minimal values of these parameters are determined for the successful creation of decision boundaries at the individual examples. Furthermore, it's presented how the neural networks behave at the classification of realistically distributed training samples, and what methods can affect the shape of the created decision boundaries.

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2 Gróf, Zoltán
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