Assessment of acoustic pollution of areas bordering highways

The work is devoted to the peculiarities of acoustic pollution of roadside territories. The studied territory is characterized by uneven acoustic load on the experimental sections of the highways of the Republic of Crimea, which is associated with the peculiarities of traffic flow and technical characteristics of cars. The article considers the indicators of the equivalent and maximum levels of motor vehicle noise. As the research result, the excess of noise level from 10 to 30 dBA was revealed. The maximum level of acoustic pollution was recorded in 10-meter zone, at a distance of 30 m from the noise source the level of acoustic pollution is reduced to 5-10 dBA.

Research of the influence of acoustic load on a piezoelectric emitter to control the cavitation erosion of materials

The paper analyzes the possibilities of research the cavitation erosion of materials that are subjected to cavitation effect. The study is carried out by a system for controlling the magnitude of the acoustic load on the piezoelectric emitter of the ultrasonic vibrating system. The analysis of the processes of interaction between the ultrasonic emitter and the processed environment was carried out on the basis of a research of the model, which was created on the basis of a system of electromechanical analogies. The analysis made it possible to reveal the dependence of the electrical impedance of the ultrasonic vibrating system on the magnitude of the acoustic load. The revealed dependencies made it possible to propose and develop a control system. It is able to provide a study of the properties that are located near the emitting surface of the ultrasonic emitter of materials influenced to cavitation ultrasonic, including under abnormal conditions (high temperatures and pressures).

INVESTIGATION OF ACOUSTIC LOAD FROM TRAFFIC FLOW ON THE EXAMPLE OF THE CITY OF KHMELNYTSKY

Introduction. Urbanization, intensification of road transport, development of urban infrastructure contributes to increased noise pollution. As traffic flows increase, so do acoustic discomfort zones, and the problem of traffic noise is becoming increasingly environmentally and socially important. Problem statement. The traffic flow significantly exacerbates the environmental problems of cities. One of the most negative factors is the increasing acoustic load. Noise pollution is currently becoming one of the most important environmental stressors. Noise levels depend on the intensity, speed, nature of traffic, type and quality of coverage, land use planning (longitudinal and transverse street profiles, building architecture, traffic lights) and the presence of greenery. Noise leads to an imbalance of auditory adaptation, regulatory processes of the central nervous system, gastrointestinal tract, hemodynamic disorders, the development of noise sickness. At long influence mechanisms of reflex and neurohumoral reactions are broken, there is a nervous pathology, attention decreases by 12-16%. Physiological and biochemical adaptation of a person to noise is impossible, in addition, noise has an inherent consuming effect. Acoustic load has a negative impact on flora and fauna. The main ones are reduced adaptive and reproductive capacity, changes in trophic nets, increased risk of predation, growth retardation, accelerated transpiration, death of leaves and flowers. This problem is most acute for urban ecosystems, as urbanization is one of the main factors in reducing biodiversity due to the loss of natural habitats, their fragmentation or drastic change. In urban conditions, many anthropogenic (industrial, transport noise) is added to the natural noise, which significantly changes the acoustic background. Currently, the noise load in megacities has increased by 12-15 dB, and the volume by three to four times. In cities with heavy traffic, the noise level is approaching 80 dB. Cartographic methods are widely used to visualize and predict noise load. Mapping the noise load of cities is relevant for Ukraine. Currently, acoustic maps have been developed only for certain districts of Kyiv. The creation of acoustic maps will help improve the ecological condition of urban areas. Purpose. Investigate and assess the level of noise load created by traffic flows on the main highways of the city of Khmelnytsky, create an acoustic map and determine the main directions of noise pollution. Research methods. general scientific (generalization, comparison, analysis and synthesis, theoretical and methodological substantiation); mathematical statistics; field (full-scale measurements of noise on the territory); cartographic (construction of a map-scheme) Results. The article highlights the problem of urban ecosystem acoustic load. It is evaluated the noise pollution of Khmelnytskyi city in Ukraine. The noise contamination model is constructed using GIS technologies within modern software package. It is shown that simulation and visualization of noise load using software makes it possible to objectively and detail estimate the acoustic situation and to propose managerial decisions development to protect the population from noise. Conclusion. The intensity of traffic noise depends on the condition and width of roads, the distance of residential buildings from the axis of the roadway. Depending on the capacity of roads, the presence of intersections changes the acoustic load. Reduction of urban traffic noise is associated with absorbing, reflecting, shielding and insulating acoustic ability. Optimization of noise protection of the urban ecosystem depends on a set of architectural and planning solutions. When introducing technical and economic characteristics of noise protection measures, it is necessary to take into account their features (practical limitations and opportunities).

Designing Protective Ecotones to Reduce Acoustic Load on the Railway Lines

According to the results of the analysis of domestic and foreign literary sources, one of the most innovative ways of ensuring the stability of anthropogenically modified ecosystems is proposed, that is the creation of a system of protective type ecotones, which will allow providing ecological safety on the railways using exclusively natural environmental restoration mechanisms. On the experimental areas, we have described the taxonomic structure of forestry groups and phytocoenotic activity of species in forest grouping. We have also calculated the closeness, viability of the tree-stands, and also the projective shelter. To determine the noise effect, the noise-permeability of forest strips and the scattering of sound-currents from planting action have been analyzed. Based on research and calculations, a zone of sound shadow is determined depending on the size of the obstacle and the length of the sound wave. The acoustic effect of reducing the sound level is determined by such factors as bandwidth, dendrological composition, and design of plantations. The one-factor dispersion analysis allowed confirming that the investigated sections of the tracks of Lviv Railways differ significantly from each other according to these data. The results of the research were also subject to correlation analysis. The coefficients of pair correlation of structural indices of protective type ecotones were calculated with reduction of acoustic load on sections of the tracks of Lviv Railways. Therefore, the interrelation with the distance, the horizontal closure of the tree canopy, the distance between the trees, the height of the shaft and the crown density were reliably established. On this basis, the multiplicity regression equation for complex estimation of acoustic load reduction and prediction of noise reduction with specified parameters of protective type ecotones were calculated.

Hygienic Substantiation of Acoustic Load Reduction Methods for Residential Premises

Summary. Introduction: Traffic flows cause noise discomfort in 75-80 % of urban territories. Automobile and railway objects located near residential buildings generate indoor noise levels that exceed current standards by 5–30 dB. Approximately 20–25% of the Russian population live in areas of excessive traffic-related acoustic load. Despite the existing methods of acoustic load reduction in residential quarters, the number of complaints about high noise exposures in residential buildings keeps growing. Our objectives was to give a hygienic substantiation of an additional method of acoustic load reduction in residential premises based on the results of analyzing the level of acoustic discomfort. Materials and methods: Measurements, assessment and analysis of the noise level along automobile roads and railways and in the reverberation chamber were carried out in accordance with the current regulatory and technical documentation using a noise/vibration meter and spectrum analyzer “EKOFIZIKA-110A”. Data was processed using the Signal+/110 Utilities software. We studied characteristics of sound insulation of airborne noise with polyester shutters with fire retardant impregnation. Results: The results showed that high noise exposure levels in residential areas with transport infrastructure. Automobile traffic flows form an acoustic load in the range of 71–84 dBA, urban railway traffic flows (trams) – 61–80 dBA, and a train – 66–77 dBA. The excess of hygienic standards at night can reach 32 to 39 dBA. The material with the best sound insulation properties was selected showing an efficiency of 5 dBA. Conclusions: Acoustic discomfort is now registered in urban residential areas with developed automobile and railroad networks. Available methods of soundproofing and noise mitigation are not effective enough or may not be used in the current urban development situation to reduce the risk of negative reactions of the human body to excessive noise exposures in residential premises, especially at night. A 5 dBA acoustic load reduction can lower the risk of negative reactions of the human body to noise exposures.

Acoustic Improvements of Aircraft Headrests Based on Electrospun Mats Evaluated Through Boundary Element Method

This work illustrates the development of passive noise control (PNC) improvements of aircraft headrests to enhance the acoustic comfort for passengers. Two PNC improvements were studied with the aim of reducing the noise perceived by passengers during flight. Two headrest configurations, with and without the lateral caps, and two different materials, a traditional foam and an innovative Silica/Polyvinylpyrrolidone (PVP) woven non-woven mat, were considered, and compared in terms of sound pressure level (SPL) perceived by passengers. Boundary element method (BEM) models were built up to evaluate the acoustic performances of different headrest configurations, varying in terms of shape and textile. A spherical distribution of monopole sources surrounding the headrests was considered as acoustic load, in such a way as to recreate a diffuse acoustic field simulating the cabin noise perceived by passengers during cruise conditions. The impact of the two PNC improvements was analyzed to envisage some general guidelines useful to design advanced headrests from the acoustic viewpoint.

EXPERIMENTAL DETERMINATION OF ACOUSTIC BEHAVIOR OF BUILDING MATERIALS BY MEANS OF ACCELEROMETERIC MEASUREMENTS

In Central Europe, brick blocks with incorporated system of voids ensuring good thermal properties are widely used in the building industry. In the present, increasingly higher acoustic load gains on importance especially in the surroundings of places with high traffic load, places close to the airports or in urban areas. This fact should be taken into consideration in the design of constructions in order to ensure their good acoustic performance. The very first step of such design lies in the experimental determination of acoustic properties of the reference construction elements which are, if necessary, subsequently optimized by adjustment of the voids volume and geometry or filling of the voids by various bulk fillers ensuring a higher level of scattering of the propagating acoustic signal. In this paper, steel prism and brick block were subjected to measurements by accelerometers in the frequency range 1 – 10 kHz in order to compare acoustic behavior of materials with a significantly different structure. Finally, frequency-dependent displacements in accelerometers position,