No abstract

This Article presents an experimental study of the capillary electrostatic instability occurring under the effect of a constant electric field on a magnetic fluid individual peak. The peaks under study occur at disintegration of a magnetic fluid layer applied on a flat electrode surface under the effect of a perpendicular magnetic field. The electrocapillary instability shows itself as an emission of charged drops jets from the peak point in direction of the opposing electrode. The charged drops emission repeats periodically and results in the peak shape pulsations. It is shown that a magnetic field affects the electrocapillary instability occurrence regularities and can stimulate its development. The critical electric and magnetic field strengths at which the instability occurs have been measured; their dependence on the peak size is shown. The hysteresis in the system has been studied; it consists in that the charged drops emission stops at a lesser electric (or magnetic) field strength than that of the initial occurrence. The peak pulsations frequency depending on the magnetic and electric field strengths and on the peak size has been measured.

In the present work the instability of a flat horizontal thin layer of a magnetic fluid (the depth of no more than 50 µm) under the action of a uniform magnetic field is studied experimentally. It was revealed that the development of instability under the action of tilted magnetic field can lead to the formation of parallel ridges on a fluid surface; the ridges undergo a transformation into hexagonal system of conical peaks with the magnetic field increasing. The necessary conditions for the formation of these surface patterns are studied. It was found that the development of instability of quite thin layers may result in layers breakup. The dependencies of instability wave number on the system physical parameters are obtained. The time for the development of instability is measured. The experimental results are compared with the existing theory and discussed.

ABSTRACT

In 2019 an Early Bronze Age settlement was recorded within the territory of Lernakert village of Shirak. It occupied the territory of the Early Iron Age fortress of Vari Berd and its surrounding area, reaching the south-western limits of the village. The homogenous and contemporary pottery fragments of the Karnut-Shengavit group associated with the second stage of the Early Bronze Age were unearthed in three test trenches. The assemblage mainly included rim fragments of pithoi, pots, deep bowls, as well as lids, handles, andiron-pedestals etc. These objects represent mainly kitchen ware and objects of everyday use. Some of them, however, bear geometrical patterns, bird and animal decorations and incised ornaments. A bronze crescent-shaped artifact was found within the territory of the site, which is one of the rare examples found in Armenia typical of this period. The mentioned findings reveal a relatively developed level of Early Bronze Age culture in Lernakert.