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Rationalization of production to improve roughness of a selected surface of rectilinear hydraulic motors
Urban, Jan ; Píška, Miroslav (referee) ; Sliwková, Petra (advisor)
In this paper, the influence of cutting parameters, machining strategies and material properties on the resulting surface roughness of a selected surface of a groove for a seal on the cover of a straight-line hydraulic motor are investigated. Based on the analysis of the results of the initial experiments of the existing production, specific measures are proposed to rationalize the manufacturing process. The effectiveness of the proposed measures is verified by further experiments carried out on real workpieces under industrial production conditions under the same manufacturing conditions. Subsequently, the results of the methods are compared with each other. The inclusion of a time delay between radial and axial feed during the finishing operation of the grooving had a very positive effect on the surface quality. The surface roughness values not only came within the prescribed tolerance but well below it. The economic evaluation shows that the rationalised production process does not have a noticeable effect on the overall cost of production and hence the results of this thesis are recommended for implementation in practice.
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Electrochemical Valorization of Lignocellulosic Biomass Amination of Furfural and 5-Hydroxymethylfurfural
Donkeng Dazie, Joel ; Koláčná, Lucie ; Urban, Jiří ; Lamač, Martin ; Ludvík, Jiří
Furfural (FF) and 5-hydroxymethylfurfural (HMF) isolated from waste lignocellulosic biomass represent renewable sources. The present contribution deals with the transformation of FF and HMF into furfuryl amines which are important precursors namely for pharmaceutical synthesis. First, FF and HMF underwent condensation reactions with various amines which were electrochemically monitored to optimize the process. The resulting Schiff bases were identified by NMR and subsequently electrochemically reduced in basic media. The vicinal diamine (aminopinacol) was the main product besides the expected furfuryl amines. This reaction is a contribution to green synthesis because it was performed electrochemically, in water, and without any metallic catalysts.
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THE REDUCTION OF SIGNAL DYNAMIC IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEX SYSTEMS
Urban, Josef ; Lúč, Andrej (referee) ; Galajda,, Pavol (referee) ; Maršálek, Roman (advisor)
This doctoral thesis is focused into the area of multicarrier radio communications systems. These systems are perspective for current and incoming mobile communications and wireless networks. Advantages of multicarrier systems like better multipath propagation resistivity are redeemed by some disadvantages. The high peak to average power ratio of transmitted signal belongs to these disadvantages, for its inconvenience for high efficient power amplification. The thesis concerns with peak to average power ratio reduction methods for OFDM systems, that belongs to the most used multicarrier systems. One of the main objectives is the modification of the existing methods with the intention of complexity reduction. Following subject of interest is the analysis of suitable methods combinations possibilities for more significant peak to average power ratio reduction. One part of this thesis is research of influence of these methods on the OFDM signals with different parameters.
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Implementation of laser technology
Urban, Jan ; Mouralová, Kateřina (referee) ; Osička, Karel (advisor)
The aim of this thesis is to describe the replacement of wire cutting laser cutting for cutting inserts made of hard material. Description of current situation in the company Vydona, tender and choice of laser and the need for post-laser workshop. The next section deals with the cutting of a particular sample. The last part of the technical economic assessment are calculated hourly rates of machines and the time and cost loads of different cutting inserts.
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Garage Control System with Remote Supervision
Urban, Jakub ; Kaczmarczyk, Václav (referee) ; Arm, Jakub (advisor)
This bachelor’s thesis describes control system of garage with remote monitoring. The first part is only theoretical and it deals with automation elements of the garage. Next part describes the choice of appropriate platform and its means of programming. Following part describes means of control of the garage door. Final part is dedicated to remote monitoring.
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