Periodical Measurements of VLF Radio Signals and Noise Sounds in Črna Jama (Postojnska Jama)

In Črna Jama, which is part of Postojnska Jama, underground measurement of VLF (Very Low Frequency) radio signals was periodically carried out in 2012 and 2013 for detection of possible pre-seismic and/or other anomalies and to ascertain suitability of VLF monitoring in a natural cave environment. The modulation of the VLF signal was connected with a powerful atmospheric front and changes of the precipitation level. VLF data showed day and night changes and also significant changes between dry and rainy periods when water from the surface reached the cave chamber through about 30 m of limestone roof. During VLF monitoring we did not receive earthquake precursor signals. VLF monitoring in a karst cave could be an option for future research in understanding pre-seismic and other anomalies. On-line connection with other VLF surface or cave monitoring sites in Europe is necessary in future VLF registration. Results of preliminary VLF monitoring showed Črna Jama to be a suitable place for future studies.Key words: VLF radio signals, noise sounds, pre-seismic anomalies, Črna Jama, Slovenia

OPTICAL DEFLECTOR CREATION FOR LASER THERAPEUTIC DEVICES

The paper deals with creation of optical deflector for management of laser radiation in physiotherapeutic devices. Design features and operation principles of electro-optical, optical-acoustic and mechanical deflectors, giving the possibility to carry out continuous or discrete scanning of a laser beam are shown. Operation mechanism of the mechanical type deflector on the example of domestic laser therapeutic scanners is described in detail. Application possibility in clinical practice for heating technique of the acupuncture points by volumetric scanning of tissues by the radiation of semiconductor lasers on wave lengths equal to 0,67 and 0,85 μm is investigated. Creation justification of the new type deflector is given. Comparison between stable and labile techniques of radiation is carried out. It is shown that more intensive warming up of a skin surface in acupuncture point projection is observed at volumetric scanning, rather than at planar scanning by laser beams. Temperature increase on a skin surface in projection of acupuncture points is detected at radiation in both the visible spectrum range (0,67 μm) and the infrared range (0,85 μm). It gives the possibility to apply this scanning method to thermal photo-activation of the point and to extend an existing arsenal of laser reflexology methods. The optical deflector is offered for medical industry, making it possible to carry out volumetric scanning of a laser beam and to facilitate the medical personnel’s work in laser therapy and reflexology consulting rooms

Связь изменений высот поверхности Антарктического ледникового покрова с движением льда и потоков подледниковой воды

The article provides phenomenological and experimental arguments that ice sheet surface fluctuation in Antarctica is mediated by ice velocity and subglacial water flow. To understand this link we use temporal coherence to refer to the comparison between vertical profile and a shifted profile along the repeat ICESat track. A profile shift due to ice velocity is determined from cross-correlation between initial and shifted profiles. Ice velocity induced fluctuation in surface elevation and deformation of the vertical profile. The degree of coherence indicates a decrease in similarity of moving vertical profiles and their deformation. The water flow beneath the ice sheet and over the subglacial lakes generates irregular rise and fall of the surface. Observations in area of Dome A and its slope have revealed such behavior of surface, where the surface is placid and ice velocity is measly 2–5 m/y.Рассматриваются феноменологические и экспериментальные аргументы, подтверждающие, что колебания ледниковой поверхности Антарктиды связаны с движением льда и потоками подледниковой воды. Движение элементов ледниковых масс сопровождается их деформацией. При движении льда со скоростью 2–5 м/год колебания поверхности обусловлены потоками подледниковой воды, их подъёмами и сбросами в подледниковые озёра. По альтиметрическим измерениям со спутника ICESat, на основании когерентности вертикальных профилей движущейся поверхности определена связь скорости движения льда в интервале от четырёх месяцев с возникающими деформациями элементов сплошного ледового тела

Evaluation of Internal Stresses in Modified Near-Surface Layer of 20Kh13 Steel during Incubation Period of Water Droplet Impact Erosion

This study investigates the change in internal stresses of ion nitrided and Cr–CrC ion-plasma-coated 20Kh13 steel samples during the incubation period of the droplet impact erosion. To obtain internal stress values, a method based on measuring the deformation (curvature) of the sample along the surface profiles before and after its modification/coating, as well as during the subsequent droplet impact has been applied. The results suggest that the initial droplet impact on the uncoated, nitrided and coated material leads to a sharp increase in the initial internal stress values. The rate of increase in internal stress decreases with the surface damage development and accumulation. The proposed method of stress evaluation can be used in selecting a criterion for comparing the erosion resistance of a material and a method for modifying its surface

Relationship of surface elevation changes of the Antarctic ice sheet with ice movement and subglacial water flow

The article provides phenomenological and experimental arguments that ice sheet surface fluctuation in Antarctica is mediated by ice velocity and subglacial water flow. To understand this link we use temporal coherence to refer to the comparison between vertical profile and a shifted profile along the repeat ICESat track. A profile shift due to ice velocity is determined from cross-correlation between initial and shifted profiles. Ice velocity induced fluctuation in surface elevation and deformation of the vertical profile. The degree of coherence indicates a decrease in similarity of moving vertical profiles and their deformation. The water flow beneath the ice sheet and over the subglacial lakes generates irregular rise and fall of the surface. Observations in area of Dome A and its slope have revealed such behavior of surface, where the surface is placid and ice velocity is measly 2–5 m/y

DYNAMICS OF ICE SHEET SURFACE OVER SUBGLACIAL LAKES IN ANTARCTICA

Progress in understanding cascades of subglacial lakes inAntarcticaand surface dynamics was derived using satellite laser altimetry measurements ICESat. The morphological and dynamical pattern troughs and swells indicate subglacial lakes and positions of their shorelines. Oscillations of surfaces in transition zones are periodic, while the changes in surface elevation above subglacial lakes are random. Elevation change in cascade occurs out of phase. The standard deviation for elevation for transition zones is100 cm, in contrast to10 cmabove the subglacial lakes. Complete insight into the cascade process and fluctuations of surface above the adjacent lakes in space and time has been derived using spectrogram. The pattern of surface displacements above cascades of subglacial lakes inAntarcticaand their transition zones are similar. In the sense of technology, the paper initiates the method of mapping subglacial lakes based on satellite laser measurements of elevation