Abstract. The problem of increasing the power efficiency of internal combustion engines by the method of its tribochemical treatment was considered. Concentrate additives Komol on the base of molybdenum complexes was developed. This concentrate reduces fuel consumption and increases engine power. In this paper the Subaru EJ-25 engine used in aviation and automotive industry was investigated before and after the tribochemical treatment by the bench tests. It's shown that adding tribochemically active additives into motor oil increases maximal engine power to 10,7% which is 8,7% on comparable engine rotation speeds. The effect was caused by reduced frictional losses as a result of the tribopolymer films formed on friction surfaces.

Abstract. The paper is devoted to investigation mechanism of cement mixture setting and stiffening. Method for registration of the acoustic oscillations induced during the heterophase transitions executing in liquid medium was proposed (method of acoustic emission (AE)). Using of conical vessel serving as a resonator allows the amplification of registered acoustic signal and provides high sensitivity of the registration. The experimental results show that the using of AE-method allows remote monitoring of the dynamics of concrete mixtures condition during setting. Therefore, this method can be successfully applied in building as a nondestructive method for determining the start and end of the solidification of the cement solution.

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The article aims to solve the problem of noise optimization of small wind turbines. The detailed analysis concentrates on accurate specification and prediction of the turbulent boundary layer noise spectrum of the blade airfoil. The angles of attack prediction for a horizontal axis wind turbine (HAWT) and the estimation based on literature data for a vertical axis one (VAWT), were conducted, and the influence on the noise spectrum was considered. The 1/3-octave sound pressure levels are obtained by semi-empirical model BPM. Resulting contour plots show a fundamental difference in the spectrum of HAWT and VAWT reflecting the two aerodynamic modes of flow that predefine the airfoil self-noise. Comparing the blade elements with a local radius of 0.875 m in the HAWT and VAWT conditions the predicted sound pressure levels are the 78.5 dB and 89.8 dB respectively. In case of the HAWT with predicted local angle of attack ranging from 2.98• to 4.63• , the acoustic spectrum will vary primarily within broadband frequency band 1.74-20 kHz. For the VAWT with the local angle of attack ranging from 4• to 20• the acoustic spectrum varies within low and broadband frequency bands 2 Hz -20 kHz.Keywords: wind turbine; airfoil self-noise; turbulent boundary layer; flow conditions; angle of attack.