Diurnal dynamics of the Umov kinetic energy density vector in the atmospheric boundary layer from minisodar measurements

The diurnal hourly dynamics of the kinetic energy flux density vector, called the Umov vector, and the mean and turbulent components of the kinetic energy are estimated from minisodar measurements of wind vector components and their variances in the lower 200 m layer of the atmosphere. During a 24 h period of continuous minisodar observations, it was established that the mean kinetic energy density dominated in the surface atmospheric layer at altitudes below ~50 m. At altitudes from 50 to 100 m, the relative contributions of the mean and turbulent wind kinetic energy densities depended on the time of the day and the sounding altitude. At altitudes below 100 m, the contribution of the turbulent kinetic energy component is small, and the ratio of the turbulent to mean wind kinetic energy components was in the range 0.01–10. At altitudes above 100 m, the turbulent kinetic energy density sharply increased, and the ratio reached its maximum equal to 100–1000 at altitudes of 150–200 m. A particular importance of the direction and magnitude of the wind effect, that is, of the direction and magnitude of the Umov vector at different altitudes was established. The diurnal behavior of the Umov vector depended both on the time of the day and the sounding altitude. Three layers were clearly distinguished: a near-surface layer at altitudes of 5–15 m, an intermediate layer at altitudes from 15 m to 150 m, and the layer of enhanced turbulence above. The feasibility is illustrated of detecting times and altitudes of maximal and minimal wing kinetic energy flux densities, that is, time periods and altitude ranges most and least favorable for flights of unmanned aerial vehicles. The proposed novel method of determining the spatiotemporal dynamics of the Umov vector from minisodar measurements can also be used to estimate the effect of wind on high-rise buildings and the energy potential of wind turbines

Spatiotemporal dynamics of the kinetic energy in the atmospheric boundary layer from minisodar measurements

Spatiotemporal dynamics of the atmospheric kinetic energy and its components caused by the ordered and turbulent motions of air masses are estimated from minisodar measurements of three velocity vector components and their variances within the lowest 5–200 m layer of the atmosphere, with a particular emphasis on the turbulent kinetic energy. The layered structure of the total atmospheric kinetic energy has been established. From the diurnal hourly dynamics of the altitude profiles of the turbulent kinetic energy (TKE) retrieved from minisodar data, four layers are established by the character of the altitude TKE dependence, namely, the near-ground layer, the surface layer, the layer with a linear TKE increase, and the transitive layer above. In the first layer, the most significant changes of the TKE were observed in the evening hours. In the second layer, no significant changes in the TKE values were observed. A linear increase in the TKE values with altitude was observed in the third layer. In the fourth layer, the TKE slightly increased with altitude and exhibited variations during the entire observation period. The altitudes of the upper boundaries of these layers depended on the time of day. The MKE values were much less than the corresponding TKE values, they did not exceed 50 m2/s2. From two to four MKE layers were distinguished based on the character of its altitude dependence. The two-layer structures were observed in the evening and at night (under conditions of the stable atmospheric boundary layer). In the morning and daytime, the four-layer MKE structures with intermediate layers of linear increase and subsequent decrease in the MKE values were observed. Our estimates demonstrated that the TKE contribution to the total atmospheric kinetic energy considerably (by a factor of 2.5–3) exceeded the corresponding MKE contribution

Comparative studies of the irradiation effects of ZrWn coating with helium and krypton ions at low and high temperatures

The effect of irradiation with low-energy helium and krypton ions on the surface structure, hardness, and corrosion resistance of ZrWN coatings was studied. Magnetron sputtering was used to form ZrWN coatings on structural steel substrates. Irradiation was carried out at room temperature and 600 °C. It was shown that the structure and properties of coatings degrade under irradiation with helium and krypton ions. Irradiation temperature affects the degree of degradation – with increasing temperature, corrosion resistance and strength characteristics of the coating decrease

Electron-ion-plasma modification of the structure and properties of commercial steels

The work is devoted to the structural-phase analysis of steels of the austenitic and martensitic grade, irradiated with a high-intensity pulsed electron beam of the submillisecond duration of exposure in the mode of the surface layer melting. A thermodynamic analysis of phase transformations occurring during heat treatment in alloys of the composition Fe-Cr-C and Fe-Cr-Ni-C, which are the basis of steels 20X13 and 12X18H10T, is carried out. It is shown that formation of solid solutions on the basis of [alpha]-iron (BCC crystalline lattice) and [gamma]- iron (FCC crystalline lattice) as well as the entire range of carbide phases of a complex elemental composition (M[23]C[6], M[7]C[3] и M[3]C, where symbol M refers to atoms of metallic elements Fe, Cr, and Ni) is possible in equilibrium conditions in given materials. The irradiation of steels 12X18H10T and 20X13 with a high-intensity pulsed electron beam of the submillisecond duration of exposure is carried out. It is shown that the electron-beam processing of steel in the melting mode and the subsequent rapid crystallization is accompanied by a significant transformation of the surface layer structure, consisting in complete dissolution of original carbide phase particles; in formation of dendritic crystallization cells of submicron sizes; in occurrence of martensitic [gamma]->[alpha] and [gamma]->[epsilon] transformation; in re-allocation of nanosized particles of carbide and intermetallic phases

Dilatation Changes in the Phase Transition Region in TiNi-based Al-loys

The paper presents the data obtained as a result of the X-ray diffraction in situ study of the parameter structure of a thin crystalline structure in the of phase transition region in alloys based on titanium nickelide depending on the deformation influence. It has been shown that dilatation changes during the transition B2-R(w) depend on the arrangement of atoms in the doping element

X-ray Diffraction Studies of Martensitic Transformations in Situ of the Pa-rameters of a Thin Crystalline Structure in TiNi Under External Loading

The paper presents the results of the X-ray diffraction study of martensitic transformations B2-R-B19' in a wide temperature range under the simultaneous action of the applied stress in the alloy based on titanium nickelide. Temperature dependences of the crystal structure parameters in phases B2, R, B19' in samples under the action of the external applied stress have been determined. It has been found that heating of a TiNi-based alloy under loading leads to a rapprochement of atomic volumes of coexisting martensitic and austenitic phases

Distribution of local deformations on the near-surface layers and scale effects of low-alloy steel specimens

This paper presents data on the study of the evolution of local microdisplacements on the surface of specimens made of ferritic-austenitic steel during compressive deformation. The experiment was performed on the test machine “Universal Testing Machine 4500” using a digital optical system Vic-3D for deformation of the specimen surface. It was found that the transition from stage III to stage IV is accompanied by an increase in the area of the region with high values of microregion displacements in the center of the specimen, which corresponds to the parabolic stage

Crystallographic parameters in geometrically and topologically close-packed superstructures

The structures of stoichiometric compositions AB, A2B, and A3B for structures, B19, L10 ,L12 , D019 , D022 , D023 , D024 , A15, C14, C15 and C36 have been investigated based on the analysis of diagrams in coordinates of space-filling coefficients [psi] on superstructural compression [delta][omega]/[omega]. On the basis of the analysis of the abovementioned diagrams, the equation [psi]=f0+f1([delta][omega]/[omega]) has been obtained, and coefficients f0 and f1 of the equation for the investigated structures have been determined. It has been established that values of coefficients f0 and f1 for Laves phases have higher values than for all other compounds