Implementation of Cisco One Platform Kit (onePK) in Computer Networks

Tato práce obsahuje postup pro vytvoření topologie využívající onePK rozhraní pro správu a automatizaci sítě. Součástí práce je ukázka tří algoritmů, které využívají tato programovatelná rozhraní a pomocí nich zajišťují kvalitu služeb v dané síti. Práce obsahuje informace o tom, co vše je třeba nastavit v rámci virtuálního prostředí, a jak je potřeba postupovat, aby nám komunikace mezi algoritmy a jednotlivými směrovači fungovala.This work include principes for creating topology which working with onePK APIs to ensure management and automation in network. This work also include three algorithms which use these programmable APIs for quality of services in this network. Part of the work is information what is necessary to setup in this virtual environment and step by step to create communication between algorithms and routers.440 - Katedra telekomunikační technikyvelmi dobř

Leveraging the Preboot eXecution Environment for Managing Computer Systems

Import 05/08/2014Tato práce je sepsána jako návod pro jednoduchou konfiguraci serveru, který by měl fungovat na principu PXE, a spouštět tak bezdiskové stanice nacházející se v lokální síti. Jedná se o shrnutí základních informací získaných z různých zdrojů a jejich aplikaci v praxi. Práce obsahuje informace o tom, co všechno potřebujeme pro spuštění PXE, a také návody, jak nastavit dílčí části serverů.This work is write like a manual of server configuration which has functionality like PXE server and it should run clients in local network without discs. It is summary of main information collected from diferent sources and aplication them in real. The work has information what we need for PXE server and a manual how configure each part of servers.440 - Katedra telekomunikační technikyvelmi dobř

Electron-Phonon Interaction in Tetrahedral Semiconductors

Effects of electron-phonon interactions on the band structure can be experimentally investigated in detail by measuring the temperature dependence of energy gaps or critical points (van Hove singularities) of the optical excitation spectra. These studies have been complemented in recent years by observing the dependence of such spectra on isotopic mass whenever different stable isotopes of a given atom are available at affordable prices. In crystals composed of different atoms, the effect of the vibration of each separate atom can thus be investigated by isotopic substitution. Because of the zero-point vibrations, such effects are present even at zero temperature (T = 0). In this paper we discuss state-of-the-art calculations of the dielectric function spectra and compare them with experimental results, with emphasis on the differences introduced by the electron-phonon interaction. The temperature dependence of various optical parameters will be described by means of one or two (in a few cases three) Einstein oscillators, except at the lowest temperatures where the T4 law (contrary to the Varshini T2 result) will be shown to apply. Increasing an isotopic mass increases the energy gaps, except in the case of monovalent Cu (e.g., CuCl) and possibly Ag (e.g., AgGaS2). It will be shown that the gaps of tetrahedral materials containing an element of the first row of the periodic table (C,N,O) are strongly affected by the electron-phonon interaction. It will be conjectured that this effect is related to the superconductivity recently observed in heavily boron-doped carbon.Comment: 17 pages, 17 fifure

Thermodynamic Properties of Stoichiometric Non-Superconducting Phase Y2BaCuO5

Y2BaCuO5 often occurs as an accompanying phase of the well-known high-temperature superconductor YBa2Cu3O7 (also known as YBCO). Y2BaCuO5, easily identifiable due to its characteristic green coloration, is often referred to as ‘green phase’ or ‘Y-211’. In this contribution, Y2BaCuO5 phase was studied in detail with a focus on its thermal and thermodynamic properties. Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were employed in the study of sample’s morphology and chemical composition. XRD data were further analyzed and lattice parameters refined by Rietveld analysis. Simultaneous thermal analysis was employed to study thermal stability. Particle size distribution was analyzed by laser diffraction. Finally, thermodynamic properties, namely heat capacity and relative enthalpy, were measured by drop calorimetry, differential scanning calorimetry (DSC), and physical properties measurement system (PPMS). Enthalpy of formation was assessed from ab-initio DFT calculations

MOC-Diatomite Composites Filled with Multi-Walled Carbon Nanotubes

The studies focusing on magnesium oxychloride cement (MOC) composites have recently become fairly widespread because of MOC’s excellent mechanical properties and environmental sustainability. Numerous fillers, admixtures and nano-dopants were studied in order to improve the overall performance of MOC-based derivatives. Some of them exhibited specific flaws, such as a tendency to aggregate, increase in porosity, aeration of the composite matrix, depreciation in water resistance and mechanical strength, etc. In this manuscript, MOC-based composites doped by multi-walled carbon nanotubes (MWCNTs) are designed and tested. In order to modify the final properties of composites, diatomite was admixed as partial substitution of MgO, which was used in the composition of the researched material in excess, i.e., the majority of MgO constituted part of MOC and the rest served as fine filler. The composites were subjected to the broad experimental campaign that covered SEM (scanning electron microscopy), EDS (energy dispersive spectroscopy), HR-TEM (high-resolution transmission electron microscopy), XRD (X-ray diffraction), OM (optical microscopy) and STA-MS (simultaneous thermal analysis with mass spectroscopy). For 28 days hardened samples, macrostructural and microstructural parameters, mechanical properties, hygric and thermal characteristics were experimentally assessed. The incorporation of MWCNTs and diatomite resulted in the significant enhancement of composites’ compactness, mechanical strength and stiffness and reduction in water absorption and rate of water imbibition. The thermal properties of the enriched MOC composites yielded interesting values and provided information for future modification of thermal performance of MOC composites with respect to their specific use in practice, e.g., in passive moderation of indoor climate. The combination of MWCNTs and diatomite represents a valuable modification of the MOC matrix and can be further exploited in the design and development of advanced building materials and components

Case study on nanoscale modification of MOC-based construction composites: Introduction of molybdenum disulfide

The excellent technical parameters of magnesium oxychloride cement (MOC) and its ability to sequester CO2 from the environment predestine its use as an alternative to Portland cement. However, its main shortcomings, low water resistance, and excessive water absorption need to be addressed to enable its wider application in construction. For this reason, the improvement of the water resistance of MOC-based composites through the use of nanosized molybdenum disulfide (MoS2) is the subject of this case study. The MOC-based composites were subjected to experimental testing of their chemical, structural and physical parameters using a wide range of advanced laboratory techniques. The composites enriched by MoS2 nanoadditive exhibited a densified and compact structure with improved mechanical parameters and stiffness. Water transport and storage were significantly decelerated and reduced by the incorporation of MoS2 nanoparticles, resulting in an improvement of water resistance, characterized by the softening coefficient, which was 66.1 % after 24 h of immersion in water, which is about 13.8 % higher than that of the reference MOC-based composite

Critical current density function of the position in a commercial REBaCuO bulk

International audienceThe progress of the melt growth synthesis technique for preparing superconducting REBaCuO bulks allows the production and commercialization of a single crystal with a diameter of 10 cm. This is in good agreement with the development of new applications such as electrical motors where superconducting bulks are used as trapped field magnets or magnetic shields [1], [2]. It is then crucial to determine the superconducting properties such as the critical temperature, critical current density and irreversible magnetic field which is commonly done with the help of an MPMS-SQUID on a millimeter-size sample. However, the inhomogeneity of performances has been reported on a bulk [3], which highlights the necessity to measure the critical properties in multiple positions along the sample radius either in a grain sector or along a grain sector boundary.We propose a similar work with a characterization carried out on a 10 cm wide commercial bulk after machining for use as magnetic shields [1]. 24 rectangular samples have been extracted in a different position from the bulk’s center, prepared and measured on a 14 T MPMS with a VSM head. Then a comparison of the superconducting properties of each sample will be presented along with trapped field measurement done on 10 others wide GdBaCuO bulks. Finally, this will allow a discussion on the readiness of this technology and its possible future development and it will point out the necessity to measure the superconducting properties in different positions.[1]R. Dorget et al., « Design of a 500 kW partially superconducting flux modulation machine for aircraft propulsion », J. Phys. Conf. Ser., july 2021.[2]R. Dorget et al., « Review on the Use of Superconducting Bulks for Magnetic Screening in Electrical Machines for Aircraft Applications », Materials, jan. 2021.[3]V. Antal et al., « Relationship between local microstructure and superconducting properties of commercial YBa2Cu3O7- δ bulk », Supercond. Sci. Technol., févr. 2020

Novel approach for manufacture of single-grain EuBCO/Ag bulk superconductors via modified single-direction melt growth

AbstractDespite the success of top‐seeded melt growth (TSMG) and TSIG, some key aspects of their manufacture need to be addressed including the presence of microstructural defects, inhomogeneities in trapped field and the difficulty of growing large‐diameter bulk monoliths. Recently, a promising new method single‐direction melt growth (SDMG) appears to address the majority of the shortcomings of TSMG and TSIG. Single‐grain EuBCO/Ag bulk with the highest peritectic temperature to date was grown by modified SDMG. This remarkable achievement was made possible by lowering the peritectic temperature of the precursor composition by the addition of silver and by using single‐grain EuBCO fabricated by TSMG as a seed. The EuBCO/Ag bulk grown by SDMG has demonstrated significant improvements in comparison to a reference TSMG sample. A reduction of approximately 30% in defect area (associated primarily with porosity), as well as a significantly enhanced homogeneity of trapped field and critical temperature, was observed. Furthermore, the critical current density curves exhibit a considerable improvement, particularly in the 2–5 T field range. The SDMG technique has considerable potential for scale‐up for the fabrication of large‐diameter bulk single grains, with only growth along the c‐axis involved during the thermal process.</jats:p