National Repository of Grey Literature 35 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Material effect in nuclear Fuel - Coolant interaction: Structural characterization of the steam explosion debris and solidification mechanism
Tyrpekl, Václav ; Nižňanský, Daniel (advisor) ; Matějec, Vlastimil (referee) ; Cognet, Gérard (referee)
Thesis Abstract This thesis has been performed under co-tutelle supervision between Charles University in Prague (Czech Republic) and Strasbourg University (France). It also profited from the background and cooperation of Institute of Inorganic Chemistry Academy of Science of the Czech Republic and French Commission for Atomic and Alternative energies (CEA Cadarache, France). Results of the work contribute to the OECD/NEA project Serena 2 (Program on Steam Explosion Resolution for Nuclear Applications). Presented thesis can be classed in the scientific field of nuclear safety and material science. It is aimed on the so-called "molten nuclear Fuel - Coolant Interaction" (FCI) that belongs among the recent issues of the nuclear reactor severe accident R&D. During the nuclear reactor melt down accident the melted reactor load can interact with the coolant (light water). This interaction can be located inside the vessel or outside in the case of vessel break-up. These two scenarios are commonly called in- and ex-vessel FCI and they differ in the conditions such as initial pressure of the system, water sub-cooling etc. The Molten fuel - coolant interaction can progress into thermal detonation called also "steam explosion" that can challenge the reactor or containment integrity. Recent experiments have shown that...
Preparation of Fe2O3/SiO2 Nanocomposites from Molecular Precursor by Sol Gel Method and Doping of Iron(III) by Trivalent Metal Cations
Brázda, Petr ; Nižňanský, Daniel (advisor) ; Matějec, Vlastimil (referee) ; Grenéche, Jean-Marc (referee)
Přírodovědecká fakulta Univerzity Karlovy v Praze katedra anorganické chemie a Univerzita Štrasburk Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague and Université de Strasbourg Příprava nanokompozitů Fezos/Sioz z moleku!árního prekurzoru metodou so! gel a dopování Že|ezitých kationtů jinými trojmocnými kationty Preparation of Fezos/Sioz Nanocomposites from Molecutar Precursor by sol Gel Method and Doping of lron(lll) by Trivalent Metal Cations Souhrn disertačnípráce Summary of Thesis Petr Brázda Šrotitete(Supervisors): RNDr. Danie| NiŽňanský, PhD' Dr. Jean-Luc Rehspringer Praha 2009 Y Abstract Iron (III) oxide fonns two well-known polymorphs - the maghemite (y-Fe2O3), which is in fact a metastable phase, and is transformed into the hematite (cr-Fe2O3) at higher temperatures. At certain conditions, elusive e-Fe2O3 can be obtained as an intermediate between these two phases. e-Fe2O3 crystallizes in orlhorhombic space group Pna\ with lattice constants a: 509.5, b = 87g.9 and c:943.7 pm and is isomophous with r-A12O3, e-Ga2O3, AIFeO: and GaFeO3. Oxygen atoms form close pseudohexagonal packing with layers ABAC. kon cations occupy four different sites, three of them are octahedrally and one is tetrahedrally coordinated. There is eight formula units in unit cell. Structure of...
Silica optical microresonators
Jelínek, M. ; Todorov, Filip ; Matějec, Vlastimil ; Chomát, Miroslav ; Kubeček, V. ; Berková, Daniela
The paper deals with the preparation of spherical silica microresonators by melting silica optical fiber with an oxygen-hydrogen flame. Resonant spectra of prepared spherical silica microresonators suitable for telecommunications and sensors purposes are also presented.
Optical microresonators for sensing and communications
Todorov, Filip ; Matějec, Vlastimil ; Chomát, Miroslav ; Berková, Daniela ; Jelínek, M. ; Kubeček, V. ; Sedlář, R.
The paper deals with optical microresonators, their preparation, characteristics and application to telecommunication and sensor purposes. Results in the preparation and characterization of spherical silica resonators achieved by the authors are presented.
Tapered optical fibers
Martan, Tomáš ; Kaňka, Jiří ; Podrazký, Ondřej ; Kašík, Ivan ; Matějec, Vlastimil
A paper is focused on a design and manufacturing microstructure optical fibers with a high nonlinear coefficient, which was reached by using a nonlinear glass and tapering a microstructure optical fiber section. In designed highly nonlinear fiber taper, supercontinum generation was simulated. Designed tapered microstructure optical fiber was manufactured with using constructed tapering apparatus. The tapering apparatus was also employed for producing fiber tips, as probes for pH measurement.
Optické senzory pro monitorování bioprocesů
Podrazký, Ondřej ; Matějec, Vlastimil ; Kuncová, Gabriela ; Pospíšilová, Marie ; Mrázek, Jan ; Kašík, Ivan ; Rose, K. ; Jaffrezic-Renault, N. ; Dzyadevych, S. ; Šašek, L. ; Scully, P. J.
The contribution presents results of the research of an optical glucose sensor. The detection of oxygen depletion caused by glucose oxidation under glucoseoxidase catalysis was used in the glucose sensors. Fluorescence quenching of ruthenium complexes by oxygen was used for the oxygen detection. The complexes and enzyme were immobilized in inorganic-organic ORMOCER membranes. Developed fiber-optic sensors enable to detect glucose in concentrations up to 3 mmol/L and with response times of about 20s.
Mřížky s dlouhou periodou v jednovidových optických vláknech zhotovené pomocí CO.sub.2./sub. laseru
Todorov, Filip ; Dunovský, J. ; Kolařík, L. ; Císařovský, P. ; Chomát, Miroslav ; Berková, Daniela ; Matějec, Vlastimil ; Kašík, Ivan
The inscription of LPGs with a period of 0.17 up to 0.98mm with a focused CO.sub.2./sub. laser beam into an experimental non-commercial optical fiber under a variety of conditions is reported. The reproducibility of the LPG’s inscription process and an experiment with multiple inscription of LPGs are presented.
Tomographic reconstruction of the geometry and refractive index profile of preforms for special fibers
Slánička, Jiří ; Peterka, Pavel ; Matějec, Vlastimil ; Kašík, Ivan ; Pospíšilová, Marie
Tomographic calculation of the refractive index profile of non-circular symmetric optical fibre performs is shown on preform for double clad pumping fibre lasers and amplifiers.
Er: Yb fibre-optic laser excited by a diode
Zavadilová, A. ; Kubeček, V. ; Honzátko, Pavel ; Kašík, Ivan ; Matějec, Vlastimil
The paper deals with the employment of special optical fiber doped in the core with ytterbium and erbium ions in a fiber laser emitting at 1540 nm. The fiber was drawn from a preform prepared by the MCVD method at it was coated with a polysiloxane polymer coating with a refractive index lower than of silica. This coating makes possible to launch light from a laser diode directly into a silica jacket of the fiber. An output power of 47 mW was measured with an excitation diode power of 860 mW.

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