Search results for "electric [charge]"
showing 10 items of 729 documents
Investigation of optical and radiation properties of oxygen deficient silica glasses
1999
The deficiency of oxygen in pure silica manifests an absorption band at 5 eV as well as an absorption band of higher intensity at 7.6 eV. The band at 5 eV is associated with lone twofold-coordinated silicon centers. The nature of the main band at 7.6 eV has been studied using silica samples with different levels of oxygen deficiency. The excitation via the 7.6 eV band produces a photoelectric response as well as inner center and recombination type luminescence. Two main luminescence bands of the twofold-coordinated silicon center appear: a blue band (2.7 eV) and a UV band (4.4 eV). Induced absorption with several bands as well as thermally stimulated luminescence with complex peak structure…
Photoelectron lifetime determination of Ag(1 1 1) films at the Fermi surface
2001
The electronic properties of 10 monolayers Ag(111) films deposited onto Si(111)-7 x 7 substrates at room temperature have been studied by scanning the photoelectron intensity at the Fermi level in different symmetry directions. The main features observed in these profiles correspond to Lorentzian-like peaks produced by the pass of the sp band through the Fermi level. A simple model has been developed, which connects the photoemission peak linewidth with the lifetime of photoelectrons excited from the Fermi level. The obtained inverse photoelectron lifetime values have been found to be in excellent agreement with the typical values of the Ag single crystals. These results support the fact th…
An interface protection system based on an embedded metrology system platform
2021
Abstract The aim of this work is to present an interface protection system (IPS) for Distributed Generators (DG) and Energy Storage Systems (ESS). The new prototype of IPS guarantees standard protection requirements, in terms of both voltage and frequency measurement accuracies and trip times. Moreover, it has the additional functionalities of implementing a communication link between the Distribution System Operator (DSO) and the DG and ESS Inverter. The new IPS is based on a smart meter platform with an integrated power line communication modem. Moreover, it has also an integrated metrology section. Experimental tests will show how this last feature allows a significant reduction of the m…
Modification of the Selectivity Properties of Tubular Ceramic Membranes after Alkaline Treatment
2017
International audience; This work focuses on the selectivity modification of ceramic membranes after a mild alkaline treatment. Filtration of pure saltwater solutions was carried out with commercial titania membranes before and after the treatment. After treatment, the rejection of NaF significantly decreased, while the rejection of NaCl and NaBr increased. Additionally, NaI and Na 2 SO 4 remained close to zero. Pore size and electrical charge being almost unchanged, only significant modifications in the dielectric effects can explain this modification of selectivity. Therefore, the surface chemistry and the interaction (nature and magnitude) with the solvent and with the species present in…
Production and properties of doped PSN electro-optical ceramics
1997
Due to multifunctionality the transparent ferroelectric ceramics is attractive to solid state chemistry and physics as a promising material for active electro-optic elements. To study doping effects on the technological processing and properties, ceramic samples of Pb1-xZxSc1/2Nb1/2O3, have been prepared, where Z: (1) Ba (0 less than or equal to x less than or equal to 1), (2) rare-earth elements: Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu (x equals 0.1), (3) PbSc1/2Nb1/2O3 doped with 5 wt.% of rare-earth oxides. Ceramic characteristics, dielectric and electro-optical parameters have been measured. Differential thermal analysis (DTA), and x-ray diffraction are used to study the infl…
A noise analyzer for monitoring static electrification current
2005
Abstract This paper presents a static electrification current signal analyzer used for measuring and processing of the variable component of the changes in electrostatic charge that occur on a solid-body/liquid boundary interface. Due to high sensitivity and low uncertainty, the analyzer allows a precise evaluation of the phenomenon generated. The device operates in a spinning-disk system. The tests carried out indicate that it is possible to measure random components which depend, to a large extent, on hydrodynamic conditions and on the properties of the liquid phase. The device can be applied to the testing of transformer oils. It can be also used for measurements of other liquids having …
Thermal conductance of thin film YIG determined using Bayesian statistics
2015
Thin film YIG (${\mathrm{Y}}_{3}{\mathrm{Fe}}_{5}{\mathrm{O}}_{12}$) is a prototypical material for experiments on thermally generated pure spin currents and the spin Seebeck effect. The $3\ensuremath{\omega}$ method is an established technique to measure the cross-plane thermal conductance of thin films, but cannot be used in YIG/GGG (${\mathrm{Ga}}_{3}{\mathrm{Gd}}_{5}{\mathrm{O}}_{12}$) systems in its standard form. We use two-dimensional modeling of heat transport and introduce a technique based on Bayesian statistics to evaluate measurement data taken from the $3\ensuremath{\omega}$ method. Our analysis method allows us to study material systems that have not been accessible with the c…
Time delay induced effects on control of linear systems under random excitation
2001
Recursive formulas in terms of statistics of the response of linear systems with time delay under normal white noise input are developed. Two alternative methods are presented, in order to capture the time delay effects. The first is given in an approximate solution obtained by expanding the control force in a Taylor series. The second, available for the stationary solution (if it exists) gets the variance of the controlled system, with time delay in an analytical form. The efficacy loss in terms of statistics of the response is discussed in detail.
Effects of 3rd-harmonic voltage content on dielectric losses of solid insulating materials
1981
Dielectric losses in solid insulating materials subjected to voltages containing 3rd harmonics are studied. By simple theoretical analysis, some curves are obtained showing the behaviour of the ratio between the dielectric losses in the distorted steady state and in a reference sinusoidal steady state, against 3rd-harmonic content. The reference sinusoidal voltage amplitudes were selected in two different ways; namely, such as to have either peak value or effective value equal to those of distorted waveform.Separate effects of harmonic content and of effective value of the applied voltage are shown through the correspondence of every 3rd-harmonic phase angle. Percentage differences between …
A finite-difference method for numerical solution of the steady-state nernst—planck equations with non-zero convection and electric current density
1986
Abstract A computer algorithm has been developed for digital simulation of ionic transport through membranes obeying the Nernst—Planck and Poisson equations. The method of computation is quite general and allows the treatment of steady-state electrodiffusion equations for multiionic environments, the ionic species having arbitrary valences and mobilities, when convection and electric current are involved. The procedure provides a great flexibility in the choice of suitable boundary conditions and avoids numerical instabilities which are so frequent in numerical methods. Numerical results for concentration and electric potential gradient profiles are presented in the particular case of the t…