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The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT.

Deep velocity models of the lithosphere of the Khoper Block and Losevskaya Suture Zone of the Voronezh crystalline massif of the Sarmatia Protocraton are obtained for the first time by the receiver function technique. The crust is determined by a four-layered structure with a waveguide in the lower part of the section. The presence of a zone of lower velocities in the upper mantle at depths of 110–150 km, which mark the mid-lithospheric discontinuity (MLD), as well as their characteristics, is identified for the first time for the Khoper Block. A complex, probably, gradient structure of the crustal–mantle transition is determined.

The influence of the distance between two circular side-by-side cylinders in a cross flow on the surface distribution of temperature and static pressure is experimentally studied. The studies were carried out at free-stream Mach numbers M equal to 0.295 and 0.365 and Reynolds numbers Re D equal to 6.4 × 10 4 and 7.9 × 10 4 , respectively. The surface distributions of the pressure coefficient and the temperature recovery factor for one of the cylinders are obtained. It is shown that, depending on the distance between the cylinders, the pressure coefficient and temperature recovery factor can be both higher and lower than the values obtained in the flow over a single cylinder with the same free-stream parameters.

The parameters of heat transfer at compressible gas flow with a favorable pressure gradient have been experimentally studied. The heat transfer coefficients and the temperature of thermally insulated (adiabatic) wall are determined using the transient heat transfer method. To estimate the degree of flow laminarization, the results obtained are compared with the known dependences for the turbulent boundary layer developing on a plate in a zero-pressure gradient flow. Some regularities of the effect of flow acceleration on the heat transfer law are revealed for the studied configurations of supersonic nozzles.

— This paper examines areas of seismic activity in Southern Siberia. It is shown that the potential earthquake source (PES) zone model created for the general seismic zoning does not fully correspond to the data on the seismic activity of the region. For seismic stations at and near hydroelectric dams, a study of seismograms of large earthquakes from different epicentral zones of natural seismicity, as well as records of the largest man-made earthquakes in the region, has been carried out. Attention is paid to platform earthquakes in the areas of hydroelectric power stations. Current power spectra are studied, which show the level of influence of signals against the background of industrial noise and microseisms, and the frequency composition and duration of seismic vibrations of dams during different earthquakes is determined. This work is the first step towards assessing the impacts of earthquakes from the most active epicentral zones on hydroelectric power stations in Siberia, taking into account the real characteristics of the signals. The level of seismic effect of industrial explosions in the region is considered. The research is aimed at clarifying and improving seismic zoning in the areas where hydropower structures are located in Southern Siberia.

Modern metastable steels with TRIP/TWIP effects have a unique set of physical-mechanical properties. They combine both high-strength and high-plasticity characteristics, which is governed by processes activated during deformation, namely, twinning, the formation of stacking faults, and martensitic transformations. To study the behavior of these phenomena in CrMnNi TRIP/TWIP steels and stainless CrNiMo steel, which does not have these effects in the temperature range under study, we used the method of acoustic emission and modern methods of signal processing, including the cluster analysis of spectral-density functions. The results of this study have been compared with a detailed microstructural analysis performed with a scanning electron microscope using electron backscatter diffraction (EBSD).

Bulk billets from commercial ingots of the alloy 1570C with different size of aluminides of transition metals were subjected to severe deformation up to the equivalent strain e∼24 via multi-step isothermal forging (MIF) with an inter-step temperature decrease from 325 to 175 °C. The high potential of MIF to produce UFG billets with enhanced balance of static and fatigue properties has been demonstrated. The role of precipitates of aluminides of transition metals and regimes of the MIF in the structure of the alloy and for the control of properties is discussed.

The Murmansk Region in the northeastern Baltic Shield has been for long assumed as aseismic. Initiated in the 1950s, the regular instrumental seismological studies allow new data on the essential increment in seismicity, demonstrated in the maps of the general seismic zoning of the territory of Russia. Powerful mining industry in the Murmansk Region also induces many seismic events. This article analyzes natural and induced seismicity and their cross-effect.

This study investigates discrepancies regarding cyclic softening of Cu processed by severe plastic deformation (SPD). All samples softened if the microhardnesses before and after fatiguing are compared. However, the effect decreases if the strain amplitude is small, Delta epsilon sub(p) < 1x10 super(-3). Samples with equiaxed subgrains were more resistant to softening and thermal recovery. All samples had `persistent' shear bands except those tested at the highest amplitudes, Delta epsilon sub(p) > 1x10 super(-2). Cu processed by SPD exhibits an enhanced fatigue life at low amplitudes. However, low thermal stability, potential for softening, and poor low-cycle properties discredit this advantage.

A procedure for locating the places of falling of fragments of a launch vehicle (LV) by recording the infrasonic signals is presented. The algorithms for generating pipes of real trajectories of falling fragments, for calculating signal parameters (sound propagation in the atmosphere), and for comparing the theoretical and experimental parameters are examined. The ways atmospheric parameters influence calculation accuracy is estimated.