Investigation of characteristics and modernization of the design exhaust tract gas turbine and gas compressors units.

The project considers the main elements of design of exhaust tract gas turbine and gas compressors units and their influence on the flow of exhaust gases. The methods for reducing the hydraulic losses in exhaust units are mentioned.В работе рассматриваются основные элементы конструкции выхлопного тракта газотурбинного и газоперекачивающего агрегата и влияние их на характер течения уходящих газов. Приводятся методы снижения гидравлических потерь в выхлопных патрубках агрегатов

Ab initio-based prediction and TEM study of silicide precipitation in titanium

In this work we applied our recently developed thermodynamic model to predict the structure of Ti-Si precipitates in α-Ti matrix of the Ti-Si alloy with total Si concentration of 0.7 wt.%. We considered all prominent Ti-Si phases such as Ti₃Si; Ti₅Si₃; Ti₅Si₄; TiSi and two TiSi₂ phases and discovered that formation of the Ti₅Si₃ phase is more favorable than that of the Ti₃Si in contradiction with the known phase diagrams. Theoretical result was confirmed by experimental investigation of microstructure and phase composition of the model Ti-0.7Si alloy annealed at 873 K for 10 h. Indeed, the only observed phase has hexagonal Ti₅Si₃ structure. To ensure the completeness of the results we calculated ab initio elastic constants for all considered Ti-Si phase

Nuclear spin cooling by helicity-alternated optical pumping at weak magnetic fields in nn-GaAs

The spin dynamics of localized donor-bound electrons interacting with the nuclear spin ensemble in $n$-doped GaAs epilayers is studied using nuclear spin polarization by light with modulated circular polarization. We show that the observed build-up of the nuclear spin polarization is a result of competition between nuclear spin cooling and nuclear spin warm-up in the oscillating Knight field. The developed model allows us to explain the dependence of nuclear spin polarization on the modulation frequency and to estimate the equilibration time of the nuclear spin system that appears to be shorter than the transverse relaxation time $T_2$ determined from nuclear magnetic resonance.Comment: Several improvements to v1, 7 pages, 5 figures, corrected list of ref

Sequence Stratigraphy and Onlap History of the Donets Basin, Ukraine: Insight into Carboniferous Icehouse Dynamics

The degree to which Permo-Carboniferous cyclothemic successions archive evidence for long-term variations in ice volume during the Late Paleozoic Ice Age is insufficiently resolved. Here we develop the sequence stratigraphy and onlap-offlap history for a 33-my interval of the Carboniferous using the U-Pb calibrated succession of the Donets Basin, Ukraine, in order to assess the relationship between sea-level, high-latitude changes in glacial extent, and climate. Integrated subsurface and outcrop data permit meter-scale correlation of 242 biostratigraphically constrained limestones and coals, and in turn individual cyclothems, across ~250 km of the Donets Basin. Rapid uniform subsidence and basinwide continuity of marker beds indicate Pennsylvanian deposition under relatively stable tectonic conditions. Three scales of sequences (avg. durations of ~140 ky, ~480 ky and 1.6 my) are recognized on the basis of stratigraphic stacking patterns and basinwide architecture of marine to terrestrial facies assemblages. The hierarchy of sequences and the geographic and stratigraphic positions of shifts in base-level sensitive facies across the Donets ramp permit the construction of an onlap-offlap history at a sub-400 ky scale. Major sea-level lowstands occur across the mid-Carboniferous boundary and during the early Moscovian. These lowstands coincide with glacial maxima inferred from high-latitude glacigenic deposits. The middle to late Pennsylvanian is characterized by a stepwise onlap, culminating in an earliest Gzhelian highstand, suggesting contraction of Carboniferous ice sheets prior to the initiation of Early Permian glaciation. The stratigraphic position of climate sensitive facies within individual Donets cyclothems indicates a turnover from seasonal sub-humid or semi-arid climate to everwet conditions during the late lowstand and maximum ice sheet accumulation. Comparison of the stratigraphic and aerial distribution of coals and evaporites in the Donets Basin with the onlap-offlap history further indicates everwet conditions during lowstands and inferred glacial maxima and drier climate during onlap and inferred ice sheet contraction at the intermediate (~0.8 to 1.6 my) and long (106 yr) time-scales. Taken together, the relationship between inferred climate and glacioeustasy suggests a likely teleconnection between high-latitude ice sheet behavior and low-latitude atmospheric dynamics

Associated data on the physicochemical properties of pedosediments, climatic and dendrochronological indicators for palaeogeographic reconstructions

Palaeogeographic markers can be justified among a large number of geochemical indicators in separate layers of pedosediments. Using individual of macroelements and trace elements as part of complex geochemical relationships and indicators allows us to determine the geochemical associations of elements that diagnose migration of the sediments at the trans-eluvial catena

Postantique soils as a source of land use information: a case study of an ancient greek agricultural area on the Northern Black Sea coast

This paper explores ancient land-use practices in order to reconstruct the original parameters of the land division system, as well as agricultural techniques employed. For postantique agricultural landscapes, an integrated geoarchaeological approach that includes GIS and remote sensing methodologies, in-field study of microrelief and soil registrograms, pedochronological dating technique, and physicochemical, geochemical, and biomorphic soil analyses has been developed and teste

Using vegetation indices to identify high chlorophyll tree cover in floodplains for carbon sequestration

The dynamics of changes of Chlorophyll vegetation index and Red-edge chlorophyll index (CIRE) for plant cover during the springsummer period on river floodplains has been studied. Landscape sections with high photosynthetic activity were identified through GIS analysi

Vortex Interferometric Microscopy with Laguerre-Gaussian Beams

In the present research, we discuss the results of analysis of coherent light beams carrying an optical vortex and propagating through the isotropic medium with a complex surface microrelief and its application to super resolution microscopy. It was shown, that phase analysis of singular beam with single charged centered optical vortex allow to retrieve information about sample surface relief. High spatial resolution caused by vortex helical phase sensitivity to disturbances in wave front after reflection or spreading through studying sample, which can be optically transparent or have a reflecting surface. This method applicable for non-destructive testing of live cells and biological tissues in real-time regime with exceeding optical diffraction limit. Vertical resolution of a microscope based on the phase singularity of Laguerre-Gaussian beams of low order can be achieved down to 5,27 nm for helium-neon laser source for optically transparent and reflecting surfaces. Keywords: optical vortex, phase, microscopy, singularit