Modeling of text and discourse worlds

The article deals with the author’s algorithm for modeling both text and discourse worlds. The importance of modeling in the contemporary linguistic paradigm is prove

High-resolution bathymetry models for the Lena Delta and Kolyma Gulf coastal zones

Arctic river deltas and deltaic near-shore zones represent important land-ocean transition zones influencing sediment dynamics and nutrient fluxes from permafrost-affected terrestrial ecosystems into the coastal Arctic Ocean. To accurately model fluvial carbon and freshwater export from rapidly changing river catchments, as well assessing impacts of future change on the Arctic shelf and coastal ecosystems, we need to understand the sea floor characteristics and topographic variety of the coastal zones. To date, digital bathymetrical data from the poorly accessible, shallow and large areas of the eastern Siberian Arctic shelves are sparse. We have digitized bathymetrical information for nearly 75,000 locations from large-scale (1:25,000 – 1:500,000) current and historical nautical maps of the Lena Delta and the Kolyma Gulf region in Northeast Siberia. We present the first detailed and seamless digital models of coastal zone bathymetry for both delta/gulf regions in 50 m and 200 m spatial resolution. We validated the resulting bathymetry layers using a combination of our own water depth measurements and a collection of available depth measurements, which showed a strong correlation (r > 0.9). Our bathymetrical models will serve as an input for a high-resolution coupled hydrodynamic-ecosystem model to better quantify fluvial and coastal carbon fluxes to the Arctic Ocean but may be useful for a range of other studies related to Arctic delta and near-shore dynamics such as modelling of submarine permafrost, near-shore sea ice, or shelf sediment transport

A novel operando approach to analyze the structural evolution of metallic materials during friction with application of synchrotron radiation

In this study, we describe an experimental setup and a new approach for operando investigation of structural evolution of materials during wear and friction. The setup is particularly suited for testing various friction pairs, including those in which both rubbing bodies are made of metals. The developed device allows circumventing the problems related to significant scattering of X-rays produced by metals and makes it possible using “real samples” in synchrotron beamlines operating in reflection mode. To demonstrate the capabilities of the device and the proposed new approach, an iron-based massive sample was subjected to thousands of friction cycles using a cemented carbide pin. The material was probed with synchrotron X-ray radiation within a few milliseconds after leaving the friction zone. The results of the microstructural and structural analysis, as well as results obtained from diverse mathematical models, allowed us to evaluate several features, including gradual accumulation of defects, microstructural refinement, dislocation density changes, surface layer oxidation, as well as several other phenomena caused by the dry sliding friction process. Mainly, it was possible to conclude that the process of wear occurred due to the cooperative action of oxidation and plastic deformation, which began during the first cycle of frictional interaction and was manifested in increasing the dislocation density, whose type was changed gradually during testing. The number of defects quickly reached a threshold value and subsequently fluctuated around it due to periodically repeated processes of defect accumulation and stress relaxation resulting from material wear. It was also observed that friction led to the quick formation of a mechanically mixed layer, consisting of the sample material and a mixture of two types of iron oxide – hematite and magnetite. The delamination of this layer was probably the primary wear mechanism

Stabilization of Ti5Al11 at room temperature in ternary Ti-Al-Me (Me = Au, Pd, Mn, Pt) systems

Ti$_5$Al$_{11}$ is known as a high-temperature phase in binary Ti-Al alloys. However, its existence at low temperatures was previously observed in ternary Ti-Al-based systems alloyed with some transition metals. In this study, we systematically evaluated Ti-Al-Me ternary systems (Me = Au, Pd, Mn, or Pt) to determine the influence of transition elements on low-temperature stabilization of Ti$_5$Al$_{11}$ phase. The temperature ranges in which Ti$_5$Al$_{11}$ existed in Ti-Al-Me systems were experimentally found using in situ synchrotron X-ray diffraction (SXRD). It was established that addition of Mn and Pt retains Ti$_5$Al$_{11}$ at room temperature. The obtained data were compared with predictions of density functional theory (DFT). The total energy, volume, and bond length are especially significantly reduced by addition of Mn and Pt. Ti5Al11 compound containing both of these elements is less prone to saturation with Ti upon preserving the lattice tetragonality and suppressing Ti$_5$Al$_{11}$ → TiAl transformation. These factors finally contribute to the retention of this phase at room temperature

Joining Ti-based metallic glass and crystalline titanium by magnetic pulse welding

Due to low thermal stability and limited critical size, metallic glasses (MGs) are frequently considered for reinforcing composites. The production technology of composites should provide the minimum heat input to preserve the disordered structure of MGs. In this study, the solid-state magnetic pulse welding (MPW) was used to join crystalline titanium and Ti-based MG. The amorphous structure of the MG layer after MPW was confirmed by synchrotron X-ray radiation diffraction (XRD), ultra-small-angle X-ray scattering (uSAXS), and transmission electron microscopy (TEM). Crystalline particles were found only in the mixing zones subjected to the strongest heating during welding. The average size of the crystalline precipitates was about 25 nm, and their phase composition corresponded to a-Ti. In addition to Ti particles, titanium oxides and nitrides could form at the interface of Ti and MG layers during MPW