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Non-linear Vibration of Planar Case of Three-blade Bundle with Dry Friction Contacts
Šnábl, Pavel ; Pešek, Luděk ; Půst, Ladislav
Using dry friction couplings (so called tie-bosses) between the blades in turbine rotors can be used to suppress dangerous resonant vibrations of turbine blades and it has been studied on our institute on various models. Experimental setup of three-blade bundle was built along with bladed wheel. The first set-up of the bundle was with blades turned 45 degrees to the disc plane. In that case the deformation of the blades causes turning of the ends of tie-bosses and edge contact together with multi-directional slip occurs. The experimental set-up was simplified herein so that the blades are parallel to the disc plane and in-line slip occurs. Although single electromagnet was used to excite the system, the first mode of vibration with no slip in tie-bosses just occurred. In case of bladed wheel, all blades have coupling through tie-bosses with neighbouring blades which stiffen them and raise their eigenfrequency. In our case, a mistuning by reducing mass of side blades caused similar behaviour. Steel to steel contact pair was used for the first tests.
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An Architecture for Global Distributed SIP Network Using IPv4 Anycast
Anděl, Ladislav ; Polívka, Michal (referee) ; Kovář, Petr (advisor)
Tato diplomová práce se zabývá metodami pro výběr nejbližší RTP proxy k VoIP klientům s použitím IP anycastu. RTP proxy servery jsou umístěny v síti Internetu a přeposílají RTP data pro VoIP klienty za síťovými překladači adres(NAT). Bez zeměpisně rozmístěných RTP proxy serverů a metod pro nalezení nejbližšího RTP proxy serveru by došlo ke zbytečnému poklesu kvality přenosu médialních dat a velkému zpoždení. Tento dokument navrhuje 4 metody a jejich porovnání s podrobnějšími rozbory metod s využitím DNS resolvování a přímo SIP protokolu. Tento dokument také obsahuje měření chování IP anycastu v porovnání mezi metrikami směrování a metrikami časovými. Nakonec dokumentu je také uvedena implemetace na SIP Express Router platformě.
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Defects of the bridge expansion joints - durability and expected lifetime
Daňa, Jan ; Ing.Ladislav Šašek, CSc. (referee) ; Pošvářová, Miloslava (advisor)
This thesis discusses the types of bridge expansion joints certified for use in the Czech Republic and their disorders. The first part was a theoretical evaluation of expansion joint failures. The second part focused on clarifying the failure of anchor bolts at the cantilever expansion joint. On the basis of determining the cause was then designed a method for determining the durability of expansion joints. Prognosis life cycles corresponds records according to administrator- repair works.
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Design of ice resurfacer
Machálek, Róbert ; Paliatka, Peter (referee) ; Křenek, Ladislav (advisor)
Theme of this diploma thesis is the design of ice resurfacer. It deals with design of a special automatic vehicle, which is able to execute the process of ice resurfacing, without human control. With regard to the protection of the environment and health of the people inside rink arena, the propulsion system is based on the electric motor, with batteries as a power source. Final design reflects innovation of the automatization in this area. The appearance supports the uniqueness and the timelessness of the ice resurfacer and it is build up on the principles of the streamline design, with emphasis on the purity of form.
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Design of nf electron-valve stereo amplifier
Dofek, Přemysl ; Rampl, Ivan (referee) ; Káňa, Ladislav (advisor)
This master’s thesis is dealing with low frequency all valve stereo amplifier unit conception for an electric guitar. The amplifier contains two independent output stages with two power tubes EL34, working in AB class, with 40Watts of power. The apparatus is equipped with two channels, EQ correctors, parallel effects loop, output selection with lowered anode power supply, selection between silicon or tube rectifier. The preamplifier works in mono mode and the stereophony is reached by dividing the signal in an added effects system. This unusual solution differs from both monaural conceptions and binaural power amplifiers which contains no preamp. It offers the possibility of stereophony without the necessity of dividing the guitar signal before the amplifier’s input. The sound that comes from the speaker on one side is effected and on the other side is dry by using monaural effects apparatus. The sound from both speakers is effected by using binaural effect apparatus. The amplifier can be used as power amplifier stage only when the return of the effect loop is used as the amplifier input. Every available possible solution is discussed in case of each block and then the most suitable is chosen. The biggest attention is paid to a proposal and calculation of both power and output transformer, ergonomical lay-out of the stages in need of the best S/N separation. The stages were simulated in Micro-Cap 9.0 and Tonestack 1.3 computer programmes. The construction was carried out with the emphasis on proper shielding and grounding. The overall stability tests were performed after building the amplifier as well as frequency characteristics with the scope and distortion with the distortion meter.
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Residential Building - Lesná
Michna, Adam ; Drobníček, Ladislav (referee) ; Menšíková, Naděžda (advisor) ; Matějka, Libor (advisor)
Bachelors thesis „Residential building Brno – Lesná“ is processed in form of project documentation. This thesis investigates the apartment building with four apartments and an underground garage with stacking parking system. The plot is situated near housing estate Lesná, close with Diviš district, which is made up of small family houses. On the plot are situated five dimensionally similar houses, this work deals with one of them in detail. This is a building with two underground floors, two floors above and a residential attic. The underground part in which there is a parking space, use of reinforced concrete structure, above-ground part is made up of a brick wall system. The house is covered with wooden gable roof truss purlin system. The house has two two-room apartments and two maisonettes three-room apartments.
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Porosity during welding aluminous alloys
Hájková, Alena ; Daněk, Ladislav (referee) ; Sigmund, Marian (advisor)
This thesis deals with the problem of occurrence of porosity in aluminous alloys and the methods of their repair in the company IFE. Theoretical part is aimed on the current state of porosity and the ways in which the be pores can be repaired. Used technologies of repairs are TIG welding and cementing. The practical part consists of experiment in which is used a method of cementing on specific part.
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Coexistence of LoRa and Wi-Fi in the RF band 2.4 GHz
Kaučiarik, Filip ; Miloš, Jiří (referee) ; Polák, Ladislav (advisor)
Diplomová práca sa zaoberá štúdiom koexistencie, ktorá môže nastať medzi bezdrôtovými komunikačnými systémami LoRa a Wi-Fi v bezlicenčnom ISM pásme 2,4 GHz. V teoretickej časti práce sú stručne popísané fyzické vrstvy obidvoch systémov. Následne sú definované spoločné frekvenčné pásma a koexistenčné scenáre, ktoré môžu vzniknúť medzi uvažovanými systémami v spoločnom rádiofrekvenčnom (RF) pásme. V experimentálnej časti práce je prezentované laboratórne meracie pracovisko, ktoré bolo navrhnuté na meranie rôznych koexistenčných scenárov medzi technológiou LoRa a Wi-Fi. Funkčnosť navrhnutej koncepcie je overená experimentálnym meraním. Výsledky meraní sú detailne komentované a prezentované. Je navrhnutá laboratórna úloha a vzorový protokol pre vzdelávacie účely v Laboratóriu Mobilných a Bezdrôtových komunikácií.
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Production single parts from thermoplastic
Enekeš, Lukáš ; Kandus, Bohumil (referee) ; Žák, Ladislav (advisor)
The project elaborated in frame of engeneering studies branch 2307. The project is submitting a design for production technology for a plastic part- bottom end of table leg made of polyamid Pa- 6. Pursuant to the literary pursuit of the problem production issues on the technical plastic segments by the technology of the injecting of a plastic into the mould (by injection mould technology). In the first part devision and identification of plastic materials are described. In the next part technological parameters and a design of the manufacturing machine and tool, including a drawing documentation, are determined. In the conclusion a simple calculation of the production costs is carried out.
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