Search results for "Volt"
showing 10 items of 2187 documents
Simulation and laboratory experimental tests of a line to shield medium voltage power line communication system
2011
A complete model of a power-line communication (PLC) system on a medium-voltage (MV) network in the case of a line-shield configuration is presented in this paper. An MV cable model in a line-shield configuration is considered together with the power transformers, the signal coupling networks, and the receiving and transmitting line coupling interface of a ST7540 FSK power-line transceiver. Simulations of the complete model of the system under consideration have been carried out for different line lengths, with and without power transformers and derivation branches. The model is validated by experimental tests performed in the laboratory. The measured results confirm the reliability of the …
Comparison of the sensitivity to spectral variation of voltage- and current-matched tandem devices with luminescent coupling and thickness optimizati…
2016
Using models that do not take luminescent coupling into account, voltage-matched tandem devices have previously been shown to be less sensitive to spectral variation than their current-matched counterparts. The present paper compares the spectral sensitivity of voltage-matched and current-matched tandem devices by applying a detailed balance model that takes luminescent coupling into account. Current-matched stacks where the thickness of the top cell thickness has been optimized are also considered. The main finding is that luminescent coupling reduces the difference in spectral sensitivity between voltage-matched and current-matched devices. There is still a significant difference, however…
Electromagnetic Full-Wave Simulation of Partial Discharge Detection in High Voltage AC Cables
2019
Partial discharge (PD) activity in the insulation system of an electrical equipment can determine the failure of the whole apparatus. PD sensors are widely used in high-voltage electrical systems as the main elements of a detecting system oriented to real time monitoring. Recently, non-invasive sensors have been proposed in industrial applications for cable and other sensitive electrical parts: they are based both on capacitive and on the electromagnetic radiating coupling. In order to assess the real performance of a new sensor produced by a high voltage AC cables manufacturer, the paper proposes electromagnetic fullwave simulation results.
Zero Ripple Current with Coupled Inductors in Continuous Conduction Mode under PWM Signals
2020
This article presents a generalized analysis to explain current ripple of an $m$ windings coupled inductor with a given coupling factor $k_{ij}$ for each pair of windings and then studies more in detail its use in the continuous conduction mode and with pulsewidth modulated signals. To determine the current ripple, a generalized expression of the equivalent inductance of each winding is calculated, including the influence of voltage unbalance. In the ideal case, the equivalent inductance shows that the current ripple can only become $m$ times smaller than that with uncoupled inductors. But in the unbalanced case, some divergences of the equivalent inductance appear that are responsible for …
Comparison of voltammetric and high performance liquid chromatographic methods for ascorbic acid determination in infant formulas
1995
Abstract Two methods — voltammetric and high performance liquid Chromatographic (HPLC) — useful for determining ascorbic acid in foods, were compared to ascertain which of them could be used for routine determination of ascorbic acid in infant formulas. Both methods were used to assay 10 identical samples of an adapted cow's milk infant formula and 10 samples of soya protein formula. Precision was determined, the variance of each method was measured, and the methods were compared with each other. The variances of the two methods were not statistically different nor was there any significant difference between the results from the two methods. Therefore, it was concluded that both methods ca…
Robust model-following control of parallel UPS single-phase inverters
2008
This paper presents a robust control technique applied to modular uninterruptible power-supply (UPS) inverters operating in parallel. When compared to conventional proportional-integral (PI) control, the proposed technique improves the response of the output voltage to load steps and to high distorted output currents, reducing the distortion of the output voltage. Furthermore, an excellent distribution of currents between modules is achieved, resulting in fine power equalization between the inverters on stream. The crossover frequency of the different loop gains involved is moderate, so that robustness to variations of the operation point and to modeling uncertainties is achieved. A compara…
Growth and defect studies of CdTe particles
2013
The paper reports the epitaxial growth of cadmium telluride (CdTe) particles by thermal deposition on cleaved planes of (001)NaCl and (001)KBr. Using high resolution transmission electron microscopy and electron diffraction it was shown that CdTe particles could have different orientation and phase (cubic or hexagonal) depending on the substrate temperature. Their most common defects are twins and stacking faults.
Microchemical surface analysis of historic copper-based coins by the combined use of FIB-FESEM-EDX, OM, FTIR spectroscopy and solid-state electrochem…
2019
[EN] A multi-technique strategy, including microscopy, spectroscopic and electrochemical techniques, is proposed to study thin corrosion layers that form on the surface of historic copper-based coins. An accurate characterisation of this external corrosion layer is important for selecting a suitable conservation and/or restoration treatment. For this purpose, a series of copper-based coins from different historical periods and provenances, which mainly exhibited atmospheric corrosion, was analysed. The morphology of the corrosion layer and the upper core of coins was studied in trenches done on coin surfaces with a focused ion beam gun, coupled to a field emission scanning electron microsco…
Archaeometric analysis of Roman bronze coins from the Magna Mater temple using solid-state voltammetry and electrochemical impedance spectroscopy
2017
Voltammetry of microparticles (VMP) and electrochemical impedance spectroscopy (EIS) techniques, complemented by SEM-EDX and Raman spectroscopy, were applied to a set of 15 Roman bronze coins and one Tessera from the temple of Magna Mater (Rome, Italy). The archaeological site, dated back between the second half and the end of the 4th century A.D., presented a complicated stratigraphic context. Characteristic voltammetric patterns for cuprite and tenorite for sub-microsamples of the corrosion layers of the coins deposited onto graphite electrodes in contact with 0.10 M HClO4 aqueous solution yielded a grouping of the coins into three main groups. This grouping was confirmed and refined usin…
Electrochemical discrimination of mints: The last Chinese emperors Kuang Hsü and Hsüan T'ung monetary unification.
2017
[EN] An electrochemical methodology for discriminating monetary emissions, a recurrent problem in much archaeological studies, is introduced. The method is based on the record of voltammetric signatures of cuprite and tenorite corrosion products in the patina using a minimally invasive nanosampling following the voltammetry of immobilized particles methodology. A model for the depth variation of voltammetric electrochemical parameters characterizing the composition of the corrosion patinas is presented. This model permits to rationalize electrochemical data and discriminate different monetary emissions. The application of this technique, corroborated by electrochemical impedance spectroscop…