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The variation of the regularities of the statistical parameters of wind turbine noise emission is described in the article. The Fast Fourier Transform algorithm was used for establishment of the wind turbine noise emission spectrum. A considerable difference of the wind turbine noise emission spectrum was established in the range of frequencies from 200 to 3 150 Hz. In the spectrum of infrasound, low frequencies (from 16 to 200 Hz) and ultrasound there are found only small changes of the noise components. The wind turbine noise emission has a broadband range and its level increases as wind velocity increases. The level of the noise decreases when the distance from wind turbines increases. The analysis of the literature shows that the wind turbine noise emission depends on aerodynamic processes and the level of the mechanical noise emission. The background noise could be evaluated when the level of the wind turbine noise emission is calculated. The investigation shows that the level of background noise, when wind velocity achieves 12 m/s, becomes equal to wind turbine noise at the distance 100 meters from the wind turbine. The theoretical model for evaluation of wind turbine noise emission depending on the distance was proposed. [ABSTRACT FROM AUTHOR]

The design formulations of pavements and bridges are significantly influenced by the uncertainties associated with the prevailing vehicle weight characteristics. Accurate modelling of load spectra and the estimation of possible vehicle growth and composition are the main components in the safety assessment of transportation structures. The vehicle weights from the existing traffic form the basis for load spectra development, and the vehicle projections are subjective to the socio-economic conditions. In this paper, the methodologies of appropriate data consideration for such representation are discussed and demonstrated based on the data from India. The load spectra are also developed for vehicular data from Interstate 95 (I-95) in New York State. In lieu of the current status of the design codes for pavements and bridges worldwide, most of the developing countries are in need of analogous models for the calibration of the design basis. [ABSTRACT FROM AUTHOR]

With the wider use of composite materials in aviation, the observation of their quality during exploitation is becoming more topical. We are of the opinion that acoustic technologies of all in one control offer us promising possibilities to observe and research the characteristics and parameters of composite materials. The purpose of this paper is to discuss some accepted ways of tuning the damping of the acoustic signals in non-homogeneous environments for research of composite materials. [ABSTRACT FROM AUTHOR]