National Repository of Grey Literature 74 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Digital Steganalysis
Dufek, Petr ; Fukač, Tomáš (referee) ; Strnadel, Josef (advisor)
This bachelor thesis deals with the field of digital steganalysis and implementation of steganalysis tool. It contains a summary of several existing tools and methods. It describes in detail LSB and PVD methods used for image steganography. It also describes steganalysis methods Chi-Square, PDH and RS analysis. The thesis includes introduction of steganalysis method SameColor. This method is based on the analysis of the length of sequences of pixels that follow each other in an image without changing the bits used for steganographic insertion of data by the LSB method. This method is effective in detecting steganograms created from cover images in the form of digital icons and symbols, where it achieves more than 95% success in classifying the analyzed images. As part of the work, a script was created for automated generation of the data set using the PVD method implemented in the xStego tool and an auxiliary script to evaluate success in classifying the analyzed files. The Chi-Square, PDH and SameColor methods were successfully implemented in the steganalysis tool in Python and their reliability in detecting steganograms was evaluated.
New generations of PVD coatings
Kantar, Filip ; Kolář, Ladislav (referee) ; Jaroš, Aleš (advisor)
Bachelor thesis deals with methods of coating, cutting tools and a new generation of coatings. In the first part are listed and described basic coating methods. The next part is aimed on coating of PVD methods. In the third part are listed basic tool materials and their characteristics. The last part is focused on new generation of coatings, their application, properties and structures.
On the increase of cutting performance of thread cutting taps with coatings
Vondra, Tomáš ; Polzer, Aleš (referee) ; Píška, Miroslav (advisor)
The aim of this master's thesis is to deal with main thread production methods and to study the influence of coatings on tap cutting performance. The high-speed steel cutting taps with different PVD coatings (Physical Vapour Deposition) were tested, while the same cutting conditions were set. Cutting torques were measured and analysed, which together with the results of evaluation of tool wear led to conclusion.
Structure and Properties of Coatings Produced by PVD Technology
Doubrava, Marek ; Horynová, Miroslava (referee) ; Čelko, Ladislav (advisor)
The submitted work is focused on study of 3rd generation DLC films produced by Platit a.s. company. Thin films are deposited utilizing filtered cathodic vacuum arc process (FCVA). The main goal of thesis was to find out the influence on film properties, caused by change of the substrate holders with different heat dissipation. The change of the substrate holders is motivated purely by economical effort to increase productivity of the deposition process. Teoretical part of the thesis is about the principles of PVD deposition process, characterization of the thin films, DLC thin films and materials used for cutting tools. Experimental part includes description of devices used for specimens analyses, including also the description of measuring process and used conditions. Acquiered results, not only the thin film thickness, adhesion or amount of sp^3 bonds, match with expected results.
Modern cutting cemented carbide tools
Vopařil, Josef ; Humár, Anton (referee) ; Píška, Miroslav (advisor)
This thesis is focused on cutting tools made of cemented carbides. It contains analysis of cemented carbides for uncoated and coated cutting tools. It contains examples of modern tools for turning, milling and drilling. Practical part of this thesis evaluates and compares cutting properties of two types of spiral drills.
Digital Image Steganography
Kolarčík, Tomáš ; Šimek, Václav (referee) ; Strnadel, Josef (advisor)
This bachelor thesis deals with digital image steganography and implements some of the available methods. This thesis describes steganography on a general level, it's history and it's current form. It also shows it's classification according to the type of carrier, the classification of the methods according to the style of hiding data and the influence of the hidden information. The primary subject of this thesis is image steganography, where facts that allow imperceptibly hide data inside image are described. A great part of this thesis is dedicated to the characteristics of the methods, which we observe and to the methods themselves. All of the methods described are implemented in a graphical and console application. The created application provides multiple image formats for hiding. In the last part, testing is performed in terms of capacity, imperceptibility  and robustness.
Reducing friction losses of piston rings
Csintalan, Radoslav ; Novotný, Pavel (referee) ; Svída, David (advisor)
This diploma thesis deals with the possibilities of reducing the friction losses of the first sealing piston rings of the VW Group 1.5 TSI, 110kW engine. The first part of the thesis theoretically deals with the issue of piston rings in terms of their classification. Reduction of friction losses is ensured by PVD and PECVD coating technology. The second part of the thesis describes the production of coated piston rings. Measurements are performed on the created coatings, which are compared and evaluated in the conclusion at the end of the thesis.
CVD and PVD coatings for decorative purposes
Švéda, Filip ; Mouralová, Kateřina (referee) ; Kalivoda, Milan (advisor)
The bachelor work is aimed to the surface coating using CVD and PVD method, not for tools but for decorative purposes. In introduction of this paper is overview of coating method and their description. Selected examples of coating items. At the end of work is evaluation of resulting effects.
HSS milling cutters deposited by nanocomposite coatings
Ludvík, Radek ; Kolář, Ladislav (referee) ; Jaroš, Aleš (advisor)
This bachelor thesis deals with nanocomposite coatings deposited on cutting tools of high speed steel. The paper describes the fundamentals of milling, tools for milling and their division and clamping. Gradually, there are analyzed problems of high speed steels (their classification, marking, properties and uses, chemical composition and heat treatment). Then there is described the main characteristics of coating methods (division of coatings into generations, surface preparation before the coating and PVD and CVD methods). The last part of the thesis focuses on the properties of nanocomposite materials and to companies dealing with their application to the high-speed steel.
Digital Image Steganography
Mazánek, Antonín ; Šimek, Václav (referee) ; Strnadel, Josef (advisor)
This bachelor's thesis introduces the steganography scientific discipline. It presents its ancient and relative recent history, mentions its current use and outlines the possible directions for steganography future. It introduces steganography into context of hiding information superior domain and highlights differences between other methods in this domain. It describes steganography subdivisions and closer deals with digital image steganography. It presents some known methods and types of digital image data. The thesis also contains more detailed description of image data in PNG format. It describes the implementation of LSB and PVD steganography methods with images in PNG format as cover object and evaluates their key properties, namely: imperceptibility, capacity and robustness. At the end of the thesis, the author's reflection on the results and possibilities of further modifications of the mentioned methods is given. 

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