No abstract

In multi-storey industrial buildings, technological processes are widespread, whereby a non-continuous in time noise regime is formed in rooms. When choosing and designing means of noise protection in these cases, multiple calculations of the energy characteristics of the noise fields of premises are performed. The effectiveness of the designed noise protection measures depends on their accuracy. The degree of accuracy is determined by the completeness of accounting in the method for calculating the factors affecting the formation of noise fields in rooms. One of them is the nature of the reflection of sound from fences. As a result of the analysis of the distribution of the reflected sound energy, it was found that in industrial premises the reflection of sound has a specularly scattered character. In this case, two reflected fields are formed in them - specular and diffusely scattered, having different principles of the appearance and dispersion of reflected sound energy. To calculate the energy characteristics of such fields, a combined calculation method is proposed in the article. Considering that the premises in industrial multi-storey buildings have a regular rectangular shape, in the proposed method, the specularly reflected energy is calculated by the method of imaginary sources, and the diffusely scattered energy is calculated on the basis of the Kuttruff integral equation. All the basic principles of building a combined computational model are stated. The accuracy of the method was assessed by comparative analysis of experimental and calculated data in rooms with a regular geometric shape. In contrast to the existing methods, the proposed method simulates the real process of the transition of the arising specularly reflected energy into the diffusely scattered one. In this case, the method takes into account the specific acoustic characteristics of each section of the fence, to be exact, its sound absorption coefficient and the scattering coefficient of reflected sound energy. In the proposed form, the method makes it possible to calculate non-continuous noise in rooms with a regular geometric shape, typical of multi-storey industrial buildings.

No abstract

Theoretical analyses and experimental data to predict durability of plasticized cement systems at an early age. Proposed to use to assess the compatibility and selection of cement and chemical additives on the early stage hydration of power rate dependence of M. Balhina. Methodology and mathematical dependences for determining the power indicator at an early age.