Electromechanical Phenomena in Ice.

Petrenko, Victor F.

doi:10.21236/ada306811

Cited by 13 publications

(16 citation statements)

References 51 publications

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“…Factors affecting triboelectrification have been analysed quantitatively by Petrenko et al [37,38] Under their experimental conditions, when the temperature decreased from À10 to À35 8C, the density of charge I increased by an order of magnitude and I collected from the surface increased non-linearly depending on the sliding velocity (v). At t ¼ À10 8C, I is proportional to v, at À14 8C, I increases as v 1.5 and at t ¼ À25 8C it increases as v 2 .…”

Section: Factors Affecting Triboelectrificationmentioning

confidence: 99%

“…At t ¼ À10 8C, I is proportional to v, at À14 8C, I increases as v 1.5 and at t ¼ À25 8C it increases as v 2 . [38] Thus, triboelectrification of snow grains by wind increases when the temperature is low and the wind speed is high. With a decrease in humidity, triboelectrification increases because dry air is a poor conductor of electrical current.…”

Section: Factors Affecting Triboelectrificationmentioning

confidence: 99%

“…Besides protons and hydroxide ions, charge can also be carried by defects in the ice, so called protonic point defects, [44] that deviate locally from the ice lattice. Petrenko [37,38] described the ice as a protonic semiconductor.…”

Section: Triboelectrification Mechanismmentioning

confidence: 99%

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Possible contribution of triboelectricity to snow - air interactions

Tkachenko¹,

Kozachkov²

2012

Environ. Chem.

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Environmental context. Polar near-surface snow can act as a chemical reactor that alters the composition and chemistry of snow and the overlying air. Although the mechanisms and driving forces of these reactions have long been debated, triboelectrification (production of electrostatic charges by friction) of snow by wind has not yet been considered as a factor. It is proposed that in polar regions, triboelectrification could significantly influence the composition and chemistry of snow.Abstract. Reactions that proceed in polar snow cover may significantly affect the chemistry of the overlying atmosphere, but mechanisms and driving forces of these reactions are still under discussion. The proposed hypothesis attempts to explain some experimental data that cannot be fully understood (e.g. the effect of wind on OH radicals, ozone and persistent organic pollutants levels) by taking into account the influence of electrical phenomena on the snow surface. We assumed that a combination of such factors as low humidity, high wind speed and low temperatures makes the influence of triboelectrification of snow significant for polar areas, where purity and the depth of snow cover prevent fast charge dissipation. The major points of the hypothesis are: (1) when the electric field reaches a value sufficient for the onset of corona discharge, various free radical processes are initiated resulting in changes in the concentrations of ozone, OH radical, nitrate, etc., and the decomposition of pollutant molecules; (2) the high electric field can stimulate transport of ions (such as bromide and nitrate) from the condensed phase to the gas phase; and (3) the ageing of charged snow can increase its electrical potential.

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Section: Factors Affecting Triboelectrificationmentioning

confidence: 99%

Section: Factors Affecting Triboelectrificationmentioning

confidence: 99%

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Possible contribution of triboelectricity to snow - air interactions

Tkachenko¹,

Kozachkov²

2012

Environ. Chem.

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“…D'après [Hobbs, 1974], la conductivité surfacique de la glace pure domine la conductivité volumique pour des températures supérieures à -10°C. Ceci est explicable par le fait qu'il existe une couche quasi-liquide [Fletcher, 1972] en dessous du point de congélation, ayant des propriétés optiques similaires à celles de l'eau, et dont l'épaisseur est de l'ordre de 50 nm à -1°C [Petrenko, 1996]. Ce changement de phase de la surface de la glace pour des températures allant de -6°C à -3°C a été observé par [Maeno, 1972] dont l'étude portait sur des cristaux de glace et pour lesquels la conductivité surfacique augmentait rapidement pour des températures supérieures à -6°C.…”

Section: Ii5 Propriétés éLectriques De La Glaceunclassified

Modélisation physique et numérique par la méthode des éléments finis de frontière de la distribution du potentiel et du champ électrique le long d'un isolateur standard de poste 735 KV recouvert de glace /

Volat¹

2002

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The main objective of the research was to calculate the voltage and electric field distributions along a standard substation insulator covered with wet-grown ice. More specifically, the research aimed to increase knowledge of the phenomena preceding flashover on substation insulators in melting conditions. Since precise measurement of voltage and especially electric field distribution along an ice-covered substation insulator is very difficult, a numerical method used in commercial software was found to be one of the best solutions, considering the difficulty of measurement. For that purpose, the Boundary Element Method {B.E.M.) was best suited to the task. Moreover, this numerical method had been successfully applied in voltage and electric field calculations along polluted insulators, which behave similarly to ice-covered insulators. Consequently, 2-D and 3-D numerical simulations were undertaken.The 2-D simulations were mainly used as the basis and support for 3-D simulations since a simple ice-covered substation insulator model had to be constructed, because numerical studies of this type were, to our knowledge, unavailable. Two-dimensional modelling of the ice-covered insulator was performed on the basis of a symmetrical diagram, separating the insulator and the ice deposit into two equal parts, based on the idea that ice only accumulates on one side of the insulator. Thus, the 2-D simulations revealed the influence of a water film and its conductivity, the influence of an air gap the location along the insulator, the influence of the air gap length, and that of a partial arc along an air gap on the voltage and electric field distributions along an ice-covered substation insulator. However, the comparison of numerical results to those of laboratory tests showed that 2-D modelling did not represent well the geometry of the insulator since the average relative error was around 22.5%, hence the need for a 3-D model to increase accuracy.For the 3-D simulations and to simplify matters, it was supposed that ice accumulated on the entire surface of the insulator, that is to say over 360°. This considered, modelling of a 15° portion of an ice-covered substation insulator was enough to simulate its general behaviour. Comparison of numerical and experimental results validated the threedimensional model. Thus, a relative average error of 2.6% between experimental and numerical results was obtained, which demonstrated the reliability and pertinence of the B.E.M. for the prediction of voltage and electric field distributions on such a complex geometry as that of an ice-covered substation insulator. Three-dimensional simulations for one accretion period and two melting periods were performed according to experimental observations in a cold chamber, from which the various models were designed. Moreover, IV study of the influence of air gaps and a partial arc on voltage and electric field distributions was undertaken.Simulations of an accretion period showed that air-gap position was mainly determined by the voltag...

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“…As sources for the electromagnetic fields, the separation, displacement or movement of bound or free charges are considered. These effects have been shown for a variety of materials and source dimensions [1][2][3][9][10][11]. The emitted frequencies range from a few Hertz up to the terahertz regime, while the EME of induced or secondary effects like gas discharges between the crack sides may have even higher frequencies.…”

Section: Introductionmentioning

confidence: 97%

Measurement and Study of Electromagnetic Emission Generated by Tensile Fracture of Polymers and Carbon Fibres

Gade

Sause

2016

J Nondestruct Eval

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Electromagnetic emission (EME) signals generated by tensile fracture of four different types of polymers and three different carbon fibre types are presented and discussed. A suitable set-up for the detection of the electric field component of EME generated by fracture of solids is proposed. Basic theoretical considerations are made about the coupling between these field components and the capacitive sensors used to directly measure the short ranged and low frequency (kHz-MHz) electric fields emitted by the generation of free surface charges and their spatial movement as dictated by the vibrational motion of the crack walls. Special focus is put on solids with low conductivity, where the influences of the material on the emitted fields is small and the detected electric signals almost solely depend on the source dynamics and the sensor characteristics. Analysis of the influence of the acquisition circuit is presented. The discussion of the electric signals emitted by tensile fracture of carbon fibres and polymer specimens comprises the influences of the material properties on the signals as well as correlations between the signals and the crack dynamics, including the crack propagation velocities.

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Electromechanical Phenomena in Ice.

Cited by 13 publications

References 51 publications

Possible contribution of triboelectricity to snow - air interactions

Possible contribution of triboelectricity to snow - air interactions

Modélisation physique et numérique par la méthode des éléments finis de frontière de la distribution du potentiel et du champ électrique le long d'un isolateur standard de poste 735 KV recouvert de glace /

Measurement and Study of Electromagnetic Emission Generated by Tensile Fracture of Polymers and Carbon Fibres

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