The paper deals with comparing the measurement of noise from the railroads in the residential zone of the town of Zvolen with the results calculated using the prediction methods “Schall 03“ (Deutsche Bundesbahn, 1990) and “Methodical instructions for the calculation of sound pressure level from transport” (MPVHD). The first is used in the Slovakia and second in the Czech Republic. The measurement results and the results obtained from the prediction methods for both measurement locations were evaluated graphically and statistically. The evaluation of the conformity of the measurement with the prediction showed that the results obtained using the method “Schall 03” are in better agreement with the measurement.
Effects of biological modification of Norway spruce wood with the wood-staining fungus Sydowia polyspora were evaluated relative to select physical and acoustical characteristics (PACHs), including the density (ρ), dynamic modulus of elasticity along the wood grain (EL), specific modulus (Esp), speed of sound along the wood grain (cL), resonant frequency (fr), acoustic constant (A), logarithmic decrement (ϑ), loss coefficient (η), acoustic conversion efficiency (ACE), sound quality factor (Q), and sound timbre. Incubation of the Norway spruce samples in S. polyspora lasted 12 w, 20 w, and 24 w. The results showed that the incubation time of spruce wood in S. polyspora did not have a statistically significant impact on most of the PACHs (ρ, EL, cL, fr, and A). However, biological modification of the spruce wood with S. polyspora had significant effects on the ϑ, η, and ACE. Treatment of the spruce wood with S. polyspora also changed the sound timbre, but the effects varied for each frequency.
For the sustainability of an important renewable resource, such as wood, it is important to significantly increase the efficiency of its processing. A large part of this raw material ends up in the wood processing industry, where it is used for the production of pulp, paper, construction and furniture timber, floors and others. Therefore, it is very important to gain the knowledge needed for optimal valuation of raw wood material, through quality detection and classification into quality classes. There are many defectoscopic methods working on different physical principles. The most familiar of these methods are semi-destructive and non-destructive, as they do not cause damage to the tree or wood during assessment. The aim of this article is to describe, assess and compare known semi-destructive and non-destructive methods for the assessment of wood properties. This article describes basic visual inspection, basic semi-destructive methods (Pilodyn, Resistograph) and advanced semi-destructive methods (SilviScan®, DiscBot®) as well. Non-destructive methods use mostly acoustic wave motion (acoustic, ultrasonic), high-frequency waves (using georadar, microwave) and methods based on visual evaluation (image, laser). At last, there are X–ray methods with the latest technology using three-dimensional (3D) computed tomography (CT). The implementation of modern non-destructive methods is of great importance for the application of principles of Industry 4.0, where these methods provide collecting of data on the material properties, in its entire production flow of log processing.
This article presents the results of an investigation of acoustic and thermophysical properties of insulation panels made from recycled technical textiles originating from the automotive industry. Measurements were performed on the samples of insulation panels (Senizol AT XX2 TL60), which were modified with liquid flame retardants (ISONEM® ANTI-FIRE SOLUTION, ECOGARD® B45, HR Prof). Another method of treatment was carried out by surface application of non-flammable facing (woven carbon fibre, nonwoven carbon fibre). Retardants were applied to the samples by surface spraying and soaking. The results showed a high ability of material to absorb sound in the frequency range 350 Hz–2 kHz. The sound absorption coefficient ranged from 0.82 to 0.9 in the frequency range 500 Hz–2 kHz. The noise reduction coefficient is 0.75. After material modification with the flame retardants, there was no significant change of sound absorption. The thermal conductivity coefficient of material before modification was 0.038 W⋅m−1⋅K−1. After application of the flame retardants, the thermal conductivity coefficient increased depending on type and method of retardant application in the range of 2.6–105.3%. The smallest change was detected after modification of material with ECOGARD® B45.
Rail transport is the second most important way of transporting people and freights by land in the European Union. Rail noise affects around 12 million people in the European Union during the day and around 9 million at night. There are two possible ways to assess environmental noise: noise measurement in situ and prediction using mathematical models. The aim of the work is based on the performed measurements and selected noise predictions to evaluate the accuracy of the prediction models and assess their sensitivity to various aspects. Two measuring points in the Banská Bystrica Self-Governing Region, within Slovakia, were selected for measurement, which is characterized by increased mobility of the population. For prediction, the two methodologies were selected (Schall 03 and Methodical instructions for the calculation of sound pressure level from transport). The results show that the Schall 03 method is sensitive to the measurement location (the value reaches half of the significance level) and to the location–period interaction. The second prediction method is sensitive to systematic error (absolute term) and, such as Schall 03, to the location–period interaction. This method systematically overestimates the results. Results showed greater accuracy of both prediction models compared to the measured noise values than the results of the authors in other countries and conditions.
When the sound wave touches the material (wall), some fraction reflex the wall, other fraction is absorbed and the rest fraction of the sound wave will go through the wall. So, in every enclosed space we can say about sound absorption, transformation of sound energy into some other energy. Sound absorption coefficient α (-) can be mentioned as criteria for the standard of sound absorption by the material. The article deals with the evaluation of sound absorption in the chosen materials which are utilised in wooden buildings, construction parts of partition walls and ceilings, floors and walls cover. There were used the following materials which are applied in the construction of wood buildings: particleboard (DTD), oriented strand board (OSB), beech plywood (PDP_BK), poplar plywood (PDP_TO), tetra pak recycled board (TETRA K), gypsum fibreboard (Fermacell), cement chipboard (CTD), plasterboard (Rigips) and medium-density fibreboard (MDF). The measurement was performed by the transfer function method in accordance with the standard ISO 10534-2. Under the frequency in the range 200 Hz – 2.0 kHz, the highest values of sound absorption coefficient were measured in CTD, PDP_TO, DTD and OSB within the interval from 0.05 to 0.53. Fermacell and Rigips have the highest values of sound absorption coefficient (0.3 – 0.4) within the frequency from 2.5 kHz to 4 kHz. At the same time, Fermacell, Rigips, but also MDF and TETRA K boards reached the lowest sound absorption (0 – 0.21) within the frequency interval 50 Hz – 2.0 kHz. Sound absorption assessed on the base of NRC coefficient was measured as very low (under 0.2) for all assessed materials, except of CTD. The tested board materials according to the standard ISO 11654 can be included among sound reflective material and little sound absorptive material. The highest level of noise reduction coefficient αNRC was measured at cement chipboard CTD (αNRC = 0.3) which can be included among absorptive materials. The results should be transformed into predictions in room and building acoustics, particularly in the design and projection of partition wall constructions in ultra-low energy buildings but also in the entire interior equipment.
The results of the investigation of the room acoustic properties influence on the perception of the sound of percussion musical instruments are presented in the paper. At first, the acoustic properties of two rooms were determined without musical instrument. Subsequently, the acoustic properties of the rooms were determined during the presentation of cajon music. On the base of reverberation time (EDT, T30), Clarity C80, Definition D50 and bass index BI) we can conclude that the room of the Hron cinema is more suitable for musical presentation, but it cannot be considered as ideal one. The Royal Hall of Zvolen Castle has a smaller influence on the sound of a percussion instrument. The influence of room acoustic properties on the resulting sound of the instrument was evaluated only on the base of results obtained with using the objective methods by the physical quantities measurement. Finally, the design of these rooms modification is presented to achieve a better sound quality of percussion instruments.
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