Search results for "charges"

Experimental and theoretical characterization of chelidonic acid structure

2022

Abstract Chelidonic acid (4-oxo-4H-pyran-2,6-dicarboxylic acid) is present in plants of Papaveraceae family, especially in Chelidonium majus. Due to its anticancer, antibacterial, hepatoprotective, and antioxidant properties, it has been used in medical treatments. In this work, the X-ray structure of methanol solvate of chelidonic acid was determined. Layers of chelidonic acid are held by hydrogen bonds via COOH and C = O fragments and additionally bridged by methanol. The formed H-bond network between two acid units is different from typical –COOH dimers observed, e.g., in crystals of isophtalic acid. The molecular structure of 2,6-dimethyl-γ-pyrone (2Me4PN) and chelidonic acid, a 2,6-dic…

Taxe d'inhabitation

2000

International audience

Los oficiales y subalternos de la Real Audiencia de Mallorca (1716-1808)

2019

The objective of this work is to know the organic structure of the officers and subordinates of the Royal Court of Majorca during the 18th century, which was the essence of the high judicial administration insular. Because of that, we approached through these relatively extensive professionals, with the description of their functions, who they were and how they obtained their charges. The article ends with an epilogue dedicated to the enlargement of the Royal Court with the creation of the second chamber during the reformist stage of Charles III to improve the high judicial administration insular.

Electrical Aging Tests on Enameled Wire Exposed to Gamma Irradiation

2011

A set of indicators for arc faults detection based on low frequency harmonic analysis

2016

In this paper a novel set of indicators is presented for arc faults detection in electrical circuits. The indicators are defined starting from an experimental characterization of the arc fault phenomenon and the study of the arcing current in several test conditions, which were chosen in accordance with the UL 1699 Standard requirements. The proposed parameters are measured by means of a high resolution low frequency spectral analysis of the arcing current, which allows to achieve a good spectral resolution even with short observation windows.

A portable instrument for the location and identification of defects generating PD

2011

A portable instrument based on an antenna probe and suitable for partial discharge detection, have been characterized through both laboratory and on-site experiments carried out on coils and stator windings of ac rotating machines. The antenna probe allows the capture of electromagnetic waves in a bandwidth of 0.1–100 MHz. Pulse signals and ac supply voltage reference are obtained by means of high-pass and low-pass filters, respectively, so avoiding the need of a direct connection with the objects under test. By this way, real-time phase resolved partial discharge patterns can be derived. Results of a comparison of the diagnostic information provided by PD patterns due to conducted and irra…

Performance of the Shape of Partial Discharge Signal Wireless Probes

2013

This paper focuses on the evaluation of the performances of three different antenna sensors suitable of Partial Discharge (PD) measurements. Monopole, triangular and spherical antennas were simulated by means of the surface moment method. The transmitting system is modeled by a power electronic device with a fault current between two metal plate. The shape of the simulated transmitted and received signals have been compared to verify the sensor the provides the best fidelity among the three. The auto-correlation function and the Pearson correlation index are adopted here for the comparison. A discussion on the dynamic characteristic of the different antenna probes and their use in different…

Arc Fault Detection Method Based on CZT Low-Frequency Harmonic Current Analysis

2017

This paper presents a method for the detection of series arc faults in electrical circuits, which has been developed starting from an experimental characterization of the arc fault phenomenon and an arcing current study in several test conditions. Starting from this, the authors have found that is it possible to suitably detect arc faults by means of a high-resolution low-frequency harmonic analysis of current signal, based on chirp zeta transform, and a proper set of indicators. The proposed method effectiveness is shown by means of experimental tests, which were carried in both arcing and nonarcing conditions and in the presence of different loads, chosen according to the UL 1699 standard…

Transient Electrical Behaviour of the TF Superconducting Coils of Divertor Tokamak Test Facility During a Fast Discharge

2022

The paper is focused on the electromagnetic analysis of the Toroidal Field (TF) superconducting coils of the Divertor Tokamak Test facility (DTT) when electrical transients occur in the TF coils system: for example, during the operations of the Fast Discharge Units (FDUs) and considering also, the simultaneous occurrence of a fault condition. During the FDU intervention, a transient voltage excitation lasting few microseconds occurs at the TF coil terminals and it electrically stresses the insulations of TF coils itsef. To investigate the voltage distribution across, inside and between different Double Pancakes (DPs) of each TF coil, a lumped parameters circuital model has been developed an…

Donnan phenomena in membranes with charge due to ion adsorption. Effects of the interaction between adsorbed charged groups

1993

A physical model for the modified Donnan phenomenon associated with ion adsorption on localized membrane sites is presented. This model accounts for the dependence of the concentration of adsorbed ions on electrolyte concentration and pH as it is influenced by the electrostatic interaction between adsorbed ions. The equilibrium thermodynamic concepts employed are based on the Donnan formalism for the ion equilibria between membrane and solution, and the Bragg–Williams approximation for an adsorption isotherm that incorported interaction between adsorbed ions. Our results include the concentration of charged groups in the membrane, the pH of the membrane phase solution, and the Donnan potent…