Investigation of a laminar boundary layer on a horizontal continuously moving plane surface in the presence of a cocurrent flow

O.G.Martynenko, V.N. Korovkin (Połock State University)On the basis of the stationary laminar boundary layer equations, an analysis of the external flow effect on the characteristics of the boundary layer of a continuously moving flat plate is carried out. Numerical and approximate analytical solutions of the problem have been obtained for different vol-ues of the parameter e, which characterizes the ratio of the velocities of the moving plate and cocur-rent flow. Correlation dependences have been constructed for determining the boundary-layer thickness and flow shear on the body surface.= На основе стационарных уравнений ламинарного пограничного слоя, анализ внешнего эффекта потока на характеристики пограничного слоя непрерывно движущейся плоской пластины осуществляется. Вычислительные и приближенные аналитические решения задачи были получены для различных Vol-ниях параметра е, характеризующего отношение скоростей движущейся пластиной и cocur-аренду потока. Корреляционные зависимости были построены для определения толщины пограничного слоя и сдвига потока на поверхности тела

Nanoindentation and Strain Characteristics of Nanostructured Boride/Nitride Films

The hardness, elastic modulus, and elastic recovery of nanostructured boride/nitride films 1–2 µm thick have been investigated by the nanoindentation technique under the maximum loads over a wide range (from 5 to 100 mN). It is demonstrated that only the hardness parameters remain constant at small loads (5–30 mN). The data obtained are discussed and compared with the parameters determined by other methods

Parallel successions of microbiomass and oribatid mites in the soil during the transformation of the forest ecosystem into an agrocenosis in the south of Western Siberia

The analysis of the state of the destructive block in gray forest soils in the Novosibirsk region was carried out. Forest, meadow under pasture and vegetable agrocenosis were selected as the objects of the study. Soil-zoological and soil-microbiological methods were used in the work. The biomass of soil microorganisms, basal respiration, metabolic coefficient, species richness and the total numbers of oribatid mites in soils were studied. Strong changes in the studied parameters in soils with different agricultural uses, compared with the soil under the forest, are demonstrated. With the deforestation and the transformation of the formed grass ecosystem to pasture, all the studied indicators decrease. When the grass ecosystem is plowed and the soil is used for a long time as an agrocenosis, a further decrease in microbiological and zoological indexes is observed. The conclusion is made about the possibility of applying the methods used in the practice of ecological monitoring of gray forest soils is made

On the Distribution of Zeros and Poles of Rational Approximants on Intervals

The distribution of zeros and poles of best rational approximants is well understood for the functions ()=||, >0. If ∈[−1,1] is not holomorphic on [−1,1], the distribution of the zeros of best rational approximants is governed by the equilibrium measure of [−1,1] under the additional assumption that the rational approximants are restricted to a bounded degree of the denominator. This phenomenon was discovered first for polynomial approximation. In this paper, we investigate the asymptotic distribution of zeros, respectively, -values, and poles of best real rational approximants of degree at most to a function ∈[−1,1] that is real-valued, but not holomorphic on [−1,1]. Generalizations to the lower half of the Walsh table are indicated

Quantum interference effects in p-Si1−xGex quantum wells

Quantum interference effects, such as weak localization and electronelectron interaction (EEI), have been investigated in magnetic fields up to 11 T for hole gases in a set of Si1−xGex quantum wells with 0.13 < x < 0.95. The temperature dependence of the hole phase relaxation time has been extracted from the magneto-resistance between 35 mK and 10 K. The spin-orbit effects that can be described within the Rashba model were observed in low magnetic fields. A quadratic negative magneto-resistance was observed in strong magnetic fields, due to the EEI effect. The hole-phonon scattering time was determined from hole overheating in a strong magnetic field