Search results for "Names"
showing 10 items of 6843 documents
The interplay of crystallization kinetics and morphology during the formation of SnO2 nanorods: snapshots of the crystallization from fast microwave …
2011
A microwave-assisted reaction pathway to rutile SnO2nanorods was investigated. The microwave-treatment significantly reduces the reaction time compared to standard hydro-/solvothermal techniques. By moving the overall process into a shorter time slot, the growth and crystal formation during the reaction could be monitored via snapshots by trapping the intermediates through quenching. To gain a better insight into the template-free growth of one-dimensional (1D) nanostructures, a parameter-dependent (various temperatures/pressures and times were investigated) study was carried out. For all materials, the phase purity and crystallite sizes were determined by X-ray powder diffraction (XRD). Th…
Thermodynamic predictions of the formation of chalcogenide glasses
1985
The understanding of glass forming ability requires quantitative information on the stable and metastable phase equilibria of binary and multicomponent systems, particularly as a function of composition and temperature. This paper discusses the success of the use of Gibbs free energy curves for the supercooled liquid relative to the stable crystalline phases to describe glass forming ability. Applications are reported for the systems GeSe2-Se, Sb2Se3-Se and GeSe2-Sb2Se3 for which experimental minimal quenching rates are available. A strongly associated regular solution model for the liquid phase gives a predicted behaviour consistent with experimental data. The method is intended to apply t…
Extrinsic Effects on the Optical Properties of Surface Color Defects Generated in Hexagonal Boron Nitride Nanosheets
2021
Hexagonal boron nitride (hBN) is a wide-band gap van der Waals material able to host light-emitting centers behaving as single photon sources. Here, we report the generation of color defects in hBN nanosheets dispersed on different kinds of substrates by thermal treatment processes. The optical properties of these defects have been studied using microspectroscopy techniques and far-field simulations of their light emission. Using these techniques, we have found that subsequent ozone treatments of the deposited hBN nanosheets improve the optical emission properties of created defects, as revealed by their zero-phonon linewidth narrowing and reduction of background emission. Microlocalized co…
Effect of sintering process and additives on the properties of cordierite based ceramics
2013
It is possible to obtain cordierite ceramics with high temperature synthesis using both synthetic and raw natural materials. This paper discusses the possibilities to obtain cordierite ceramics, replacing part of required oxides with raw materials from various Latvian deposits of dolomite and clay. The obtained raw cordierite powders were ground in two modes (3 and 12 hours) and fired at 1200 °C. Ceramic samples were characterized by hydrostatic weighting method; crystalline phase composition was studied by XRD. Obtained samples were evaluated by their mechanical (compressive) strength and linear coefficient of thermal expansion (CTE). Thermal shock resistance was tested using water quenchi…
Generation of narrowband antisymmetric lamb waves using a formed laser source in the ablative regime
2007
A formed laser source, using a four-element lenticular array, is used in the ablative regime to generate select, narrowband, acoustic plate waves. The arrangement of the array produces acoustical signals that have frequencies compatible with the response of the broadband capacitive air-coupled transducer used in this study. A simplified concept is presented to explain the effect of a line array source on the frequency content of acoustic waves. The analytical model for a point pulse surface displacement is derived from the point load solution to Lamb's problem. The point pulse displacement elements of a line array source are summed mathematically, taking into account all applicable propagat…
Cu Polyimidazole Thioether Complexes : Comparison of RDF's Reconstructed from XAFS and XRD Data
1997
Radial distribution functions (RDF) reconstructed from XAFS data (Cu K-edge at low and room temperatures) are compared with RDF's constructed from XRD crystallographic data of Cu polyimidazole thioether complexes. New EDA software package possibilities are used to reconstruct RDFs: (i) model independent RDF reconstruction, and (ii) multi shell - cumulant fitting. RDF's obtained from XRD data are broadened with Debye Waller factors calculated from XAFS. This way the structural disorder (set of distances) and thermal (vibrational) disorder are quantitatively taken into account in each RDF reconstruction approach. Within experimental error the three sets of RDF'S agree well with each other for…
Performance assessment of PPP surveys with open source software using the GNSS GPS-GLONASS-Galileo constellations
2020
In this work, the performance of the multi-GNSS (Global Navigation Satellite System) Precise Point Positioning (PPP) technique, in static mode, is analyzed. Specifically, GPS (Global Positioning System), GLONASS, and Galileo systems are considered, and quantifying the Galileo contribution is one of the main objectives. The open source software RTKLib is adopted to process the data, with precise satellite orbits and clocks from CNES (Centre National d&rsquo
Backward solution of PV nodes in radial distribution networks
2009
In this paper an iterative backward methodology to solve radial distribution networks with fixed voltage (PV) nodes and with constant power loads or mixed loads (with at least one component with constant power) is proposed. The method developed, although deriving conceptually from the backward/forward (b/f) methodology, presents only the backward phase in which all the network variables are evaluated. In themethods developed up until nowfor the solution of such systems, PV nodes are taken into account at the end of each iteration by evaluating, based on the known quantities of the network, the unknowns associated with PV nodes. In the methodology developed here the unknowns relevant to PV n…
The modulation transfer function and signal-to-noise ratio of different digital filters: a technical approach.
2011
The aim of this study was to illustrate the influence of digital filters on the signal-to-noise ratio (SNR) and modulation transfer function (MTF) of digital images. The article will address image pre-processing that may be beneficial for the production of clinically useful digital radiographs with lower radiation dose.Three filters, an arithmetic mean filter, a median filter and a Gaussian filter (standard deviation (SD) = 0.4), with kernel sizes of 3 × 3 pixels and 5 × 5 pixels were tested. Synthetic images with exactly increasing amounts of Gaussian noise were created to gather linear regression of SNR before and after application of digital filters. Artificial stripe patterns with defin…
Interpretation of absorption edges by resonant electronic spectroscopy: experiment and theory
2004
Abstract Resonant electronic spectroscopy consists in measuring a non-radiative decay process (Auger or autoionization process) excited with photon energies around an absorption edge. The resonant spectra carry information both on the nature of the electronic transitions near the absorption edge by scanning the very first empty orbitals above the Fermi level (through the absorption process), and, on the other hand, on the atomic electronic configuration through the lineshape of the observed decay process. In this paper, after a quick review of the pioneering works in this field, we show that resonant measurements and their theoretical modeling can be used to precisely interpret complex abso…