Centrum výzkumu a využití obnovitelných zdrojů energie

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    Mathematical model of Mobile Circulatory Module for ex-vivo lungs perfusion
    (IFAC, 2015-05-13) Šolc, František; Zezulka, František; Veselý, Ivo
    The article deals with mathematical modelling of a system for ex-vivo lung perfusion. The system which is modelled here is named Mobile Circulatory Module and is designed for transport of live lungs namely porcine or human lungs. Transported lungs should be used for various research or even for transplantation. The article describes mathematical model of thermal circuit and hydraulic circuit which are vital parts of the MCM to secure living conditions of the transported organ. Mathematical model is simulated with MATLAB Simulink and shows good qualitative correspondence with real behavior of the system. Based on math model there is designed control algorithm for temperature control and there is discussed control of perfusion liquid as well.
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    Spatio-temporal description of the cavitating flow behavior around NACA 2412 hydrofoil
    (IOP Publishing, 2015-12-06) Rudolf, Pavel; Štefan, David; Sedlář, Milan; Kozák, Jiří; Habán, Vladimír; Huzlík, Rostislav
    Spatio-temporal description of the cavitating flow around hydrofoil with 8 degrees incidence using proper orthogonal decomposition (POD) is presented. POD is a suitable tool, which provides information not only about the flow dynamics, but also about relevance of different flow structures. POD also enables to track energy transport within the domain and energy transfer among the eigenmodes of the flow field. Analysis documents change of the flow structure for decreasing cavitation number, which can be most likely attributed to sheet/cloud cavitation transition.
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    Evaluation of different solutions of faulted phase earthing technique for an earth fault current limitation
    (IET, 2017-06-12) Topolánek, David; Toman, Petr; Ptáček, Michal; Dvořák, Jaromír
    The study is focused on evaluation of different types of prototypes of automatics for additional faulted phase earthing (FPE), which are used for earth fault (EF) current reduction in resonant earthed distribution network. Three prototypes of these automatics have been installed in Czech distribution network, the first one utilises direct connection of faulty phase–to-earthing system of supply substation, the second one utilises connection through resistor and the last one through reactor. The contribution is mainly focused on detail analysis of operational differences of these types of FPE systems based on case study of compensated distribution network. The main aim is to specify and describe benefits and disadvantages of individual FPE applications. The results could be used for evaluation of best solution of FPE application which could be chosen for an EF current reduction in compensated distribution network.
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    Negative lead-acid battery electrodes doped with glass fibres
    (ESG, 2015-03-01) Bača, Petr; Křivík, Petr; Vaculík, Sebastian; Tošer, Pavel
    Negative lead-acid battery electrodes doped with microscopic glass fibres show similar properties during accelerated partial state of charge cycling as those doped with carbon or titanium dioxide, including a long cycle life of up to 84,000 cycles. The optimum amount of this additive in the negative active mass seems to be between 2 and 3 wt. %.
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    Effect of Heat Treatment on the Corrosion and Mechanical Properties of Electrolytical Composite Ni-B Coatings
    (ESG, 2014-08-01) Oriňáková, Renáta; Oriňák, Andrej; Kupková, Miriam; Sabalová, Mária; Straková Fedorková, Andrea; Kabátová, Margita; Kaľavský, František; Sedlaříková, Marie
    Electrodeposition of composite coatings with nickel matrix and boron micro-particles was investigated. Nickel - boron layers were deposited potentiodynamically at 12.5 mV/s on cylindrical samples prepared from iron powder in a stirred heterogeneous system formed by a Watts type nickel plating bath and dispersed boron micro-particles. The effect of boron powder amount in plating bath and heat treatment on the corrosion resistance and hardness of the composite Ni-B coatings was evaluated. Corrosion properties of coated cylindrical iron samples were investigated in 1 mol dm-3 NaCl solution using potentiodynamic polarization method. The structure of coating layers was established using scanning electron microscopy (SEM) and light optical microscopy (LOM). The content of incorporated boron particles increased with the boron amount in plating bath. Homogeneous distribution of boron particles in deposited coating layer was observed for both as-deposited samples and samples heat treated at 400 °C. Boron particles were not observed on the surface of the deposits heated at higher temperatures. Generally, addition of boron micro-particles to the nickel matrix as well as the heat treatment deteriorated the corrosion resistance of iron samples coated with composite Ni-B films. The dependence of the corrosion properties of composite layers on boron particle loading was not proved. The decrease of microhardness on the surface but increase of microhardness on the cross- section of composite Ni-B coating layer due to the heat treatment was observed.