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1
Content available Experimental verification of similarity criteria for sound absorption of simple metamaterials
Chojak Aleksandra
Vibrations in Physical Systems
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2022
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Vol. 33, nr 2
art. no. 2022211
EN
The paper concerns the dimensional analysis of simple acoustic metamaterials and its experimental verification in a computer model. Due to their decreased thickness possible because of the thermoviscous losses and sound dispersion that occur in acoustic metamaterials, such structures are gaining popularity, both as sound absorbers and diffusers. This implies the need to find their equivalents to be used at scale - both for modeling interiors with metamaterials and developing more complicated structures. The paper discusses the dimensional analysis performed for a generalized unit cell of a metamaterial with a resonator. The dimensional analysis shows the need for scaling both the geometrical dimensions of the structure and the parameters of the medium - air. The dimensional analysis was derived based on the transfer matrix method and was proven correct with the finite element method model. The paper also discusses the consequences of neglecting the air criteria, which are impossible to be fulfilled. This opens the question of finding new criterial numbers allowing the correct reflection of acoustic metamaterials at scale.
2
Content available Analysis of dynamic properties of the PRT vehicle-track system
Kozłowski M., Choromański W., Kowara J.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2015
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Vol. 63, nr 3
799--806
EN
The paper presents the issue of modelling the system of the PRT vehicle – track. The PRT – Personal Rapid Transit concept is defined as an innovative transport system composed of small vehicles (3–5 persons) moving on the light infrastructure situated at a height of above 5 meters above the ground. This is a system that combines the features of individual and public transport. An important feature of this system is the implementation of the transport approach known as the ‘point to point’ rule that is to say between the initial and the final stop the vehicle does not stop at the intermediate stops. The vehicle has no driver. Routing choice and collision avoidance are performed through a complex computer system.
3
Content available Laserowe stanowisko symulacyjne mili pomiarowej
Panasiuk A.
Autobusy : technika, eksploatacja, systemy transportowe
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2013
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R. 14, nr 3
1873-1883
PL
Artykuł zawiera przedstawienie laserowego stanowiska pomiarowego imitującego Milę Pomiarową w warunkach laboratoryjnych. Poruszono podstawy teoretyczne pomiarów prędkości okrętu i ich odniesienie do modelu. Przedstawione zostały także wyniki pomiarów prędkości modelu redukcyjnego na basenie pomiarowym dla wybranych warunków.
EN
Paper presents the measured mile full imitation post in laboratory conditions. Theoretical base of ship speed measurement in relate to model was also included. Author presents some model speed measurement results on maneuvering pool for selected conditions.
4
Content available Badanie cyrkulacji modelu kutra ratowniczego PROJ R-20 na basenie manewrowym
Panasiuk A.
Autobusy : technika, eksploatacja, systemy transportowe
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2013
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R. 14, nr 3
1465-1474
PL
Artykuł zawiera wyniki badania cyrkulacji modelu redukcyjnego i ich przykładowe porównanie z cyrkulacją jednostki rzeczywistej. Przedstawiona została również całość urządzeń z wyposażenia laboratorium, które zostały wykorzystane w badaniach oraz model redukcyjny – obiekt badawczy. Zawarto również założenia do badań, zarys teorii, opis procedury badawczej i warunki przeprowadzenia prób.
EN
Paper presents the results of ship’s model circulation research using the maneuvering pool laboratory and some comparison witch a real ship. Instruments, methods, equipment and the object of research are also presented. Base theoretical illustrations, research circumstances, procedures and some important factors are included too.
5
Content available Numerical Compensation of Air Absorption of Sound in Scale Model Measurements
Ćirić D. G., Pantić A.
Archives of Acoustics
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2012
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Vol. 37, No. 2
219-225
EN
The absorption of sound in air represents one of the main problems of the scale model measurements. This absorption, especially at higher frequencies, is considerably greater than the value determined by the law of acoustical similarity between the full scale and the scale model. Different alternatives are applied for compensation of the excess air absorption including a numerical compensation. In this paper, a modified approach to numerical compensation is proposed. It is based on compensation of the sound decay only, and not background noise. As a consequence, there is no an increase of background noise in the compensated impulse response. The results obtained by the proposed procedure are compared to the corresponding ones obtained by the other procedures.
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