No abstract

The main sources of noise pollution in modern cities, that generate significant levels of sound pressure, which significantly, sometimes at times exceed permissible noise levels have been identified. The consequences of the negative impact of noise of the urban environment on the human body, fauna and flora are described. The sanitary-hygienic, engineering-technical, architectural-planning, construction-acoustic and economic-social aspects of scientific researches concerning protection of the environment from noise pollution are singled out. The main methods and ways to reduce urban noise are described, among which are: reducing the sound power level of existing equipment and vehicles, or replacing them with less noisy ones, and during design-taking measures to minimize noise emissions from machines; carrying out timely cleaning, adjustment, repair of machines, mechanisms and equipment, restriction or complete prohibition of noisy works and operation of the most intensive noise sources at night; rational orientation of the noise source or place of noise radiation, taking into account the direction indicator; placement of noise sources and objects of protection – at the maximum possible distance from each other; the use of building structures with improved sound insulation, the use of sound-absorbing materials for lining the enclosing structures of buildings and structures; zoning of sources and objects of protection, application of territorial gaps, noise protection buildings, acoustic screens and strips of greenery. It was found that the maximum possible impact on noise pollution of modern cities and surrounding areas can be achieved in the case of integrated application of methods, means of protection against acoustic blocking of the duration, direction and use of noise emissions in its sources and through noise level on the way to its spread, as well as through the implementation of appropriate organizational and technical measures.

No abstract

Among the several kinds of thermoplastic adhesives, structured and non-structured polyvinyl acetate (PVA) adhesives have a rather wide application and are used currently for forming adhesive joints from different wood species, especially oakwood. To ensure proper conditions of oakwood adhesive joints use, it is important to have fast and accurate methods of predicting their strength and durability. The strength changes of the oakwood adhesive joints bonded with structured and non-structured PVA adhesives have been investigated by conducting long-term experiments. Based on the generalization of experimental data and theoretical predictions regarding the mechanism of the adhesive seam formation, equations that allow calculating theoretically the strength of oakwood adhesive joints bonded with non-structured and structured PVA adhesives have been proposed. The pro-posed equations reproduce experimental data with suffi-cient accuracy of ±3.5 % within the temperature range from 251 K to 306 K and humidity range from 40 % to 100 %, and therefore, are recommended for practical use.

Наведено результати імітаційного моделювання термопластичних полівінілацетатних клейових з'єднань деревини з використанням CAD/CAE систем. Розроблено алгоритм імітаційного моделювання в CAD/CAE системах напружено-деформаційного стану термопластичних клейових з'єднань деревини залежно від зміни температури та вологості. Доповнено бібліотечну базу даних CAD/CAE систем фізико-механічними та фізико-хімічними характеристиками різних порід деревини та клейовими матеріалами на термопластичній основі. Розроблений алгоритм імітаційного моделювання та сформована база даних дає змогу моделювати зміну вологості, температури та напружено-деформаційного стану у будь-якій точці термопластичного клейового з'єднання деревини залежно від зміни вологості та температури.