Tribocorrosion research of NI-Al₂O₃/TIO₂ composite materials obtained by the method of electrochemical deposition

The purpose of this study was to perform electrochemical deposition and tribocorrosion studies of composite materials based on NI-Al₂O₃/TIO₂. During the research, electrochemical deposition of various composite materials was carried out, while comparison was made with base materials such as duplex steel and electrochemically precipitated nickel. Working particles were characterized using laser dispersion methods and the deposits were characterized by SEM using different detectors (backscattered and secondary electrons), EDX (energy-dispersive x-ray spectroscopy) and FIB (focused ion beam). Based on the photographs taken in SEM, the dependence of the amount of particles in the coating on the concentration of TiO₂ particles in the solution and the time of electrochemical deposition of the coatings was determined. Tribological studies of Steel/Ni/Ni-TiO₂ materials, tribocorrosion studies of Ni/Ni-TiO₂ materials, comparative construction of track profiles obtained by optical method based on confocal microscopy and determination of the height and width of profiles from the material used were also carried out.Метою даного дослідження було проведення електрохімічного осадження і трібокоррозіонних досліджень композитних матеріалів на основі NI-Al₂O₃/TIO₂. За час досліджень було виконано електрохімічне осадження різних композитних матеріалів, при цьому проводилося порівняння з базовими матеріалами, такими як дуплексна сталь і електрохімічно осаджений нікель. Були охарактеризовані робочі частки з використанням методів лазерної дисперсії, а покриття характеризувалися в SEM з використанням різних детекторів (Зворотне розсіювання і Вторинні електрони), EDX (енергодісперсная рентгенівська спектроскопія) і FIB (сфокусований іонний пучок). На основі виконаних знімків в SEM була визначена залежність кількості частинок в покритті від концентрації частинок TiO₂ в розчині і часу електрохімічного осадження покриттів. Також були проведені трибологічне дослідження матеріалів Сталь/Ni/Ni-TiO₂, трібокоррозіонне дослідження матеріалів Ni/Ni-TiO₂, порівняльна побудова профілів доріжок отриманих оптичним методом на основі конфокальної мікроскопії та визначення залежності висоти і ширини профілів від використовуваного матеріалу

Peculiarities of Excitation of Large-Scale Plasma Density Irregularities During Modification of the Ionospheric F<inf>2</inf> Region by High-Power HF Radio Waves

© 2016 Springer Science+Business Media New YorkWe present the experimental results concerning the features of large-scale artificial plasma-density irregularities excited in the ionospheric F2 region by high-power HF radio waves. The experiments were performed in recent years using the SURA heating facility. It is shown that at the altitude of the pump-wave reflection, these irregularities are most efficiently generated in the magnetic zenith region. The effect of enhancement of the large-scale irregularity generation at the edge of the pump-wave beam is revealed. The results of studying large-scale irregularities recorded at the altitudes of the topside ionosphere are presented. Experimental results concerning the features of the internal gravity waves generated at the ionospheric altitudes during periodic heating of the ionospheric plasma by high-power HF radio waves are summarized and their possible influence on generation of artificial ionospheric irregularities at a long distance from the heater is discussed

Symmetry and the macroscopic dynamics of antiferromagnetic materials in the presence of spin-polarized current

Antiferromagnetic (AFM) materials with zero or vanishingly small macroscopic magnetization are nowadays the constituent elements of spintronic devices. However, possibility to use them as active elements that show nontrivial controllable magnetic dynamics is still discussible. In the present paper we extend the theory [A.F.Andreev, V.I.Marchenko, Sov. Phys. --- Uspekhi, 23 (1980), 21] of macroscopic dynamics in AFMs for the cases typical for spin-valve devices. In particular, we consider the solid-like magnetic dynamics of AFMs with strong exchange coupling in the presence of spin-polarized current and give an expression for the current-induced Rayleigh dissipation function in terms of the rotation vector for different types %generalized potential of AFMs. Basing on the analysis of linearized equations of motion we predict the current-induced reorientation and AFM resonance, and found the values of critical currents in terms of AFMR frequencies and damping constants. We show the possibility of current-induced spin-diode effect and second-harmonic generation in AF layer. The proposed approach is generalized for the description of current-related phenomena in inhomogeneous AFMs.Comment: 10 pages, 3 figures, to be submitted to PR

Peculiarities of excitation of large-scale plasma density irregularities during modification of the ionospheric F<inf>2</inf> region by high-power HF radio waves

© 2016 Springer Science+Business Media New York.We present the experimental results concerning the features of large-scale artificial plasma-density irregularities excited in the ionospheric F2 region by high-power HF radio waves. The experiments were performed in recent years using the SURA heating facility. It is shown that at the altitude of the pump-wave reflection, these irregularities are most efficiently generated in the magnetic zenith region. The effect of enhancement of the large-scale irregularity generation at the edge of the pump-wave beam is revealed. The results of studying large-scale irregularities recorded at the altitudes of the topside ionosphere are presented. Experimental results concerning the features of the internal gravity waves generated at the ionospheric altitudes during periodic heating of the ionospheric plasma by high-power HF radio waves are summarized and their possible influence on generation of artificial ionospheric irregularities at a long distance from the heater is discussed

Multi-Sensors Observations of Pre-Earthquake Signals. What We Learned from the Great Tohoku Earthquake?

The lessons learned from the Great Tohoku EQ (Japan, 2011) will affect our future observations and an analysis is the main focus of this presentation. Multi-sensors observations and multidisciplinary research is presented in our study of the phenomena preceding major earthquakes Our approach is based on a systematic analysis of several physical and environmental parameters, which been reported by others in connections with earthquake processes: thermal infrared radiation; temperature; concentration of electrons in the ionosphere; radon/ion activities; and atmospheric temperature/humidity [Ouzounov et al, 2011]. We used the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model, one of several possible paradigms [Pulinets and Ouzounov, 2011] to interpret our observations. We retrospectively analyzed the temporal and spatial variations of three different physical parameters characterizing the state of the atmosphere, ionosphere the ground surface several days before the March 11, 2011 M9 Tohoku earthquake Namely: (i) Outgoing Long wave Radiation (OLR) measured at the top of the atmosphere; (ii) Anomalous variations of ionospheric parameters revealed by multi-sensors observations; and (iii) The change in the foreshock sequence (rate, space and time); Our results show that on March 8th, 2011 a rapid increase of emitted infrared radiation was observed and an anomaly developed near the epicenter with largest value occurring on March 11 at 07.30 LT. The GPS/TEC data indicate an increase and variation in electron density reaching a maximum value on March 8. Starting from this day in the lower ionosphere there was also observed an abnormal TEC variation over the epicenter. From March 3 to 11 a large increase in electron concentration was recorded at all four Japanese ground-based ionosondes, which returned to normal after the main earthquake. We use the Japanese GPS network stations and method of Radio Tomography to study the spatiotemporal structure of ionospheric perturbations, and to distinguish ionospheric responses to processes of EQ preparation against the effects of other factors. The 2-D snapshots of the electron density over Japan showed abnormal increase over the maximum stress during the night, a few hours before the main shock. Our results from recording atmospheric and ionospheric conditions during the earthquake indicate the presence of anomalies in the atmosphere and ionospheres occurring consistently over regions of maximum stress near the epicenter. Due to their long duration (hours and days) and spatial appearance (only over the Sendai region) these results do not appear to be caused by meteorological or magnetic activity. They reveal the existence of atmospheric and ionospheric phenomena occurring prior to the earthquake, which indicates new evidence of a distinct coupling between the lithosphere and atmosphere/ionosphere. Similar results have been reported before the catastrophic events in Chile (M8.8, 2010), Italy (M6.3, 2009) and Sumatra (M9.3, 2004)

Spatial Structure of Large-Scale Plasma Density Perturbations HF-Induced in the Ionospheric F<inf>2</inf> Region

© 2016 Springer Science+Business Media New YorkWe consider the experimental results obtained by studying the large-scale structure of the HF-disturbed ionospheric region. The experiments were performed using the SURA heating facility. The disturbed ionospheric region was sounded by signals radiated by GPS navigation satellite beacons as well as by signals of low-orbit satellites (radio tomography). The results of the experiments show that large-scale plasma density perturbations induced at altitudes higher than the F2 layer maximum can contribute significantly to the measured variations of the total electron density and can, with a certain arrangement of the reception points, be measured by the GPS sounding method

Spatial Structure of Large-Scale Plasma Density Perturbations HF-Induced in the Ionospheric F <inf>2</inf> Region

© 2016, Springer Science+Business Media New York.We consider the experimental results obtained by studying the large-scale structure of the HF-disturbed ionospheric region. The experiments were performed using the SURA heating facility. The disturbed ionospheric region was sounded by signals radiated by GPS navigation satellite beacons as well as by signals of low-orbit satellites (radio tomography). The results of the experiments show that large-scale plasma density perturbations induced at altitudes higher than the F2 layer maximum can contribute significantly to the measured variations of the total electron density and can, with a certain arrangement of the reception points, be measured by the GPS sounding method

From Multi-Sensors Observations Towards Cross-Disciplinary Study of Pre-Earthquake Signals. What have We Learned from the Tohoku Earthquake?

The lessons we have learned from the Great Tohoku EQ (Japan, 2011) how this knowledge will affect our future observation and analysis is the main focus of this presentation.We present multi-sensors observations and multidisciplinary research in our investigation of phenomena preceding major earthquakes. These observations revealed the existence of atmospheric and ionospheric phenomena occurring prior to theM9.0 Tohoku earthquake of March 11, 2011, which indicates s new evidence of a distinct coupling between the lithosphere and atmosphere/ionosphere, as related to underlying tectonic activity. Similar results have been reported before the catastrophic events in Chile (M8.8, 2010), Italy (M6.3, 2009) and Sumatra (M9.3, 2004). For the Tohoku earthquake, our analysis shows a synergy between several independent observations characterizing the state of the lithosphere /atmosphere coupling several days before the onset of the earthquakes, namely: (i) Foreshock sequence change (rate, space and time); (ii) Outgoing Long wave Radiation (OLR) measured at the top of the atmosphere; and (iii) Anomalous variations of ionospheric parameters revealed by multi-sensors observations. We are presenting a cross-disciplinary analysis of the observed pre-earthquake anomalies and will discuss current research in the detection of these signals in Japan. We expect that our analysis will shed light on the underlying physics of pre-earthquake signals associated with some of the largest earthquake event